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Sample records for spun form domes

  1. Mitigating Abnormal Grain Growth for Friction Stir Welded Al-Li 2195 Spun Formed Domes

    NASA Technical Reports Server (NTRS)

    Chen, Po-Shou; Russell, Carolyn

    2012-01-01

    Formability and abnormal grain growth (AGG) are the two major issues that have been encountered for Al alloy spun formed dome development using friction stir welded blanks. Material properties that have significant influence on the formability include forming range and strain hardening exponent. In this study, tensile tests were performed for two 2195 friction stir weld parameter sets at 400 F to study the effects of post weld anneal on the forming range and strain hardening exponent. It was found that the formability can be enhanced by applying a newly developed post weld anneal to heat treat the friction stir welded panels. This new post weld anneal leads to a higher forming range and much improved strain hardening exponent. AGG in the weld nugget is known to cause a significant reduction of ductility and fracture toughness. This study also investigated how AGG may be influenced by the heating rate to the solution heat treatment temperature. After post-weld annealing, friction stir welds were strained to 15% and 39% by compression at 400 F before they were subjected to SHT at 950 F for 1 hour. Salt bath SHT is very effective in reducing the grain size as it helps arrest the onset of AGG and promote normal recrystallization and grain growth. However, heat treating a 18 ft dome using a salt bath is not practical. Efforts are continuing at Marshall Space Flight Center to identify the welding parameters and heat treating parameters that can help mitigate the AGG in the friction stir welds.

  2. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Formed Domes

    NASA Technical Reports Server (NTRS)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Simulated service testing (SST) development was required to help qualify a new 2195 aluminum lithium (Al-Li) alloy spin forming dome fabrication process for the National Aeronautics and Space Administration (NASA) Exploration Development Technology Program. The application for the technology is to produce high strength low weight tank components for NASA s next generation launch vehicles. Since plate material is not currently manufactured large enough to fabricate these domes, two plates are joined by means of friction stir welding. The plates are then pre-contour machined to near final thicknesses allowing for a thicker weld land and anticipating the level of stretch induced by the spin forming process. The welded plates are then placed in a spin forming tool and hot stretched using a trace method producing incremental contours. Finally the dome receives a room temperature contour stretch to final dimensions, heat treatment, quenching, and artificial aging to emulate a T-8 condition of temper. Stress corrosion cracking (SCC) tests were also performed by alternate immersion in a sodium chloride (NaCl) solution using the typical double beam assembly and with 4-point loaded specimens and use of bent-beam stress-corrosion test specimens under alternate immersion conditions. In addition, experiments were conducted to determine the threshold stress intensity factor for SCC (K(sub ISCC)) which to our knowledge has not been determined previously for Al-Li 2195 alloy. The successful simulated service and stress corrosion testing helped to provide confidence to continue to Ares 1 scale dome fabrication

  3. Simulated Service and Stress Corrosion Cracking Testing for Friction Stir Welded Spun Form Domes

    NASA Technical Reports Server (NTRS)

    Stewart, Thomas J.; Torres, Pablo D.; Caratus, Andrei A.; Curreri, Peter A.

    2010-01-01

    Damage tolerance testing development was required to help qualify a new spin forming dome fabrication process for the Ares 1 program at Marshall Space Flight Center (MSFC). One challenge of the testing was due to the compound curvature of the dome. The testing was developed on a sub-scale dome with a diameter of approximately 40 inches. The simulated service testing performed was based on the EQTP1102 Rev L 2195 Aluminum Lot Acceptance Simulated Service Test and Analysis Procedure generated by Lockheed Martin for the Space Shuttle External Fuel Tank. This testing is performed on a specimen with an induced flaw of elliptical shape generated by Electrical Discharge Machining (EDM) and subsequent fatigue cycling for crack propagation to a predetermined length and depth. The specimen is then loaded in tension at a constant rate of displacement at room temperature until fracture occurs while recording load and strain. An identical specimen with a similar flaw is then proof tested at room temperature to imminent failure based on the critical offset strain achieved by the previous fracture test. If the specimen survives the proof, it is then subjected to cryogenic cycling with loads that are a percentage of the proof load performed at room temperature. If all cryogenic cycles are successful, the specimen is loaded in tension to failure at the end of the test. This standard was generated for flat plate, so a method of translating this to a specimen of compound curvature was required. This was accomplished by fabricating a fixture that maintained the curvature of the specimen rigidly with the exception of approximately one-half inch in the center of the specimen containing the induced flaw. This in conjunction with placing the center of the specimen in the center of the load train allowed for successful testing with a minimal amount of bending introduced into the system. Stress corrosion cracking (SCC) tests were performed using the typical double beam assembly and with 4

  4. Large Spun Formed Friction-Stir Welded Tank Domes for Liquid Propellant Tanks Made from AA2195: A Technology Demonstration for the Next Generation of Heavy Lift Launchers

    NASA Technical Reports Server (NTRS)

    Stachulla, M.; Pernpeinter, R.; Brewster J.; Curreri, P.; Hoffman, E.

    2010-01-01

    Improving structural efficiency while reducing manufacturing costs are key objectives when making future heavy-lift launchers more performing and cost efficient. The main enabling technologies are the application of advanced high performance materials as well as cost effective manufacture processes. This paper presents the status and main results of a joint industrial research & development effort to demonstrate TRL 6 of a novel manufacturing process for large liquid propellant tanks for launcher applications. Using high strength aluminium-lithium alloy combined with the spin forming manufacturing technique, this development aims at thinner wall thickness and weight savings up to 25% as well as a significant reduction in manufacturing effort. In this program, the concave spin forming process is used to manufacture tank domes from a single flat plate. Applied to aluminium alloy, this process allows reaching the highest possible material strength status T8, eliminating numerous welding steps which are typically necessary to assemble tank domes from 3D-curved panels. To minimize raw material costs for large diameter tank domes for launchers, the dome blank has been composed from standard plates welded together prior to spin forming by friction stir welding. After welding, the dome blank is contoured in order to meet the required wall thickness distribution. For achieving a material state of T8, also in the welding seams, the applied spin forming process allows the required cold stretching of the 3D-curved dome, with a subsequent ageing in a furnace. This combined manufacturing process has been demonstrated up to TRL 6 for tank domes with a 5.4 m diameter. In this paper, the manufacturing process as well as test results are presented. Plans are shown how this process could be applied to future heavy-lift launch vehicles developments, also for larger dome diameters.

  5. DomeHaz, a Global Hazards Database: Understanding Cyclic Dome-forming Eruptions, Contributions to Hazard Assessments, and Potential for Future Use and Integration with Existing Cyberinfrastructure

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Calder, E.; Loughlin, S.

    2013-12-01

    Dome-forming eruptions can extend for significant periods of time and can be dangerous; nearly all dome-forming eruptions have been associated with some level of explosive activity. Large Plinian explosions with a VEI ≥ 4 sometimes occur in association with dome-forming eruptions. Many of the most significant volcanic events of recent history are in this category. The 1902-1905 eruption of Mt. Pelée, Martinique; the 1980-1986 eruption of Mount St. Helens, USA; and the 1991 eruption of Mt. Pinatubo, Philippines all demonstrate the destructive power of VEI ≥ 4 dome-forming eruptions. Global historical analysis is a powerful tool for decision-making as well as for scientific discovery. In the absence of monitoring data or a knowledge of a volcano's eruptive history, global analysis can provide a method of understanding what might be expected based on similar eruptions. This study investigates the relationship between large explosive eruptions and lava dome growth and develops DomeHaz, a global database of dome-forming eruptions from 1000 AD to present. It is currently hosted on VHub (https://vhub.org/groups/domedatabase/), a community cyberinfrastructure for sharing data, collaborating, and modeling. DomeHaz contains information about 367 dome-forming episodes, including duration of dome growth, duration of pauses in extrusion, extrusion rates, and the timing and magnitude of associated explosions. Data sources include the The Smithsonian Institution Global Volcanism Program (GVP), Bulletin of the Global Volcanism Network, and all relevant published review papers, research papers, and reports. This database builds upon previous work (e.g Newhall and Melson, 1983) in light of newly available data for lava dome eruptions. There have been 46 new dome-forming eruptions, 13 eruptions that continued past 1982, 151 new dome-growth episodes, and 8 VEI ≥ 4 events since Newhall and Melson's work in 1983. Analysis using DomeHaz provides useful information regarding the

  6. Properties of Ti-6Al-4V spun formed fuze supports

    SciTech Connect

    Moody, N.R.; Gates, G.

    1985-05-01

    Spin forming is designated as the primary fabrication process for the Ti-6A1-4V, W-87 fuze support. This process reduces the amount of rough machining during production, the cost of the starting material and the lead time from order to delivery of finished parts compared with parts made from forgings. However, because the amount of deformation from the spin forming process varies greatly within the part, the properties resulting from spin forming the fuze supports are unknown. This study shows that the properties and microstructure of the highly deformed walls of the fuze support are similar to those of forgings, while the properties and microstructure of the lightly deformed nose are similar to those of the parent plate. A solution treatment at 1750/sup 0/F/1h/WQ (954/sup 0/C) followed by a 900/sup 0/F (482/sup 0/C) four hour age gives the desired properties. Additionally, microstructural evaluation shows that the temperatures during spin forming are maintained within desired limits and that no significant microstructural changes occur during subsequent elevated temperature processing of the finished part. This study shows that solution treated and aged parts meet all required properties for all conditions to which the fuze supports will be subjected.

  7. Hot vacuum creep forming of scale shuttle external tank dome caps

    NASA Technical Reports Server (NTRS)

    Thomas, A. O.

    1974-01-01

    The feasibility of forming shuttle external tank dome caps by hot vacuum creep was investigated for a sub-scale configuration. Aluminum 2219-T37 at an elevated temperature equivalent to the artificial aging time and temperature was used to produce the T87 condition while achieving MIL-HBK -5 properties of 2219-T87 aluminum alloy material. A feasibility analysis was conducted in two phases: the design and build of a sub-scale hot vacuum creep forming (HVCF) die and the forming evaluation of various cap configurations. The contour was constant in all evaluations. This configuration was found to be too severe for the limited forming force available by HVCF.

  8. Friction-Stir-Welded and Spin-Formed End Domes for Cryogenic Tanks

    NASA Technical Reports Server (NTRS)

    Hales, S. J.; Tayon, W. A.; Domack, M. S.

    2012-01-01

    Manufacturing of single-piece end domes for cryogenic tanks employing spin forming of tailored, friction-stir-welded blanks of Al-Li alloy 2195 plate offers cost and reliability benefits. The introduction of plastic deformation into a friction stir weld is a unique feature of the proposed manufacturing route. This investigation addressed abnormal grain growth [AGG] within the friction stir weldments during postfabrication processing of a prototype dome. The phenomenon of AGG was observed during the solution heat treatment [SHT] phase of T8 tempering and is a major concern for meeting specifications. Such abrupt microstructural transitions can be detrimental to notch-sensitive mechanical properties, such as ductility and/or fracture toughness. If the issue of AGG cannot be resolved, then the acceptance of this approach as a viable manufacturing route may be in jeopardy. The innovative approach adopted in this investigation was the insertion of a stand-alone, Intermediate Annealing Treatment [IAT] between the spin forming and T8 processing operations. A simple, recovery annealing step was deemed to be the most readily-scalable solution when fabricating thin-walled, ellipsoidal domes. The research effort culminated in the development of an effective IAT, which resulted in a significant decrease in AGG following SHT. The processing philosophy adopted in designing the IAT is outlined and the microstructural reasons for success are discussed. The analytical results presented are consistent with promoting continuous grain growth during the IAT, thereby suppressing AGG during the SHT.

  9. Recent Developments in the UltraForm Finishing and UltraSurf Measuring of Axisymmetric IR Domes

    DTIC Science & Technology

    2010-06-08

    Approved for public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES Presented at Mirror Technology Days, Boulder, Colorado, USA......deterministic fabrication solution for a wide range of newly developed windows , domes and mirrors . COMMERCIALIZATION  UltraForm Finishing ( UFF

  10. Net Shape Spin Formed Cryogenic Aluminum Lithium Cryogenic Tank Domes for Lower Cost Higher Performance Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Curreri, Peter A.; Hoffman, Eric; Domack, Marcia; Brewster, Jeb; Russell, Carolyn

    2013-01-01

    With the goal of lower cost (simplified manufacturing and lower part count) and higher performance (higher strength to weight alloys) the NASA Technical Maturation Program in 2006 funded a proposal to investigate spin forming of space launch vehicle cryogenic tank domes. The project funding continued under the NASA Exploration Technology Development Program through completion in FY12. The first phase of the project involved spin forming of eight, 1 meter diameter "path finder" domes. Half of these were processed using a concave spin form process (MT Aerospace, Augsburg Germany) and the other half using a convex process (Spincraft, Boston MA). The convex process has been used to produce the Ares Common Bulkhead and the concave process has been used to produce dome caps for the Space Shuttle light weight external tank and domes for the NASDA H2. Aluminum Lithium material was chosen because of its higher strength to weight ratio than the Aluminum 2219 baseline. Aluminum lithium, in order to obtain the desired temper (T8), requires a cold stretch after the solution heat treatment and quench. This requirement favors the concave spin form process which was selected for scale up. This paper describes the results of processing four, 5.5 meter diameter (upper stage scale) net shaped spin formed Aluminum Lithium domes. In order to allow scalability beyond the limits of foundry and rolling mills (about 12 foot width) the circular blank contained one friction stir weld (heavy lifter scales require a flat blank containing two welds). Mechanical properties data (tensile, fracture toughness, stress corrosion, and simulated service testing) for the parent metal and weld will also be discussed.

  11. Effect of P addition on glass forming ability and soft magnetic properties of melt-spun FeSiBCuC alloy ribbons

    NASA Astrophysics Data System (ADS)

    Xu, J.; Yang, Y. Z.; Li, W.; Chen, X. C.; Xie, Z. W.

    2016-11-01

    The dependency of phosphorous content on the glass forming ability, thermal stability and soft magnetic properties of Fe83.4Si2B14-xPxCu0.5C0.1 (x=0,1,2,3,4) alloys was investigated. The experimental results showed that the substitution of B by P increased the glass forming ability in this alloy system. The Fe83.4Si2B10P4Cu0.5C0.1 alloy shows a fully amorphous character. Thermal stability of melt-spun ribbons increases and temperature interval between the first and second crystallization peaks enlarges with the increase of P content. And the saturation magnetic flux density (Bs) shows a slight increase with the increase of P content. The Fe83.4Si2B11P3Cu0.5C0.1 nanocrystalline alloy exhibits a high Bs about 200.6 emu/g. The Bs of fully amorphous alloy Fe83.4Si2B10P4Cu0.5C0.1 drops dramatically to 172.1 emu/g, which is lower than that of other nanocrystallines. Low material cost and excellent soft magnetic properties make the FeSiBPCuC alloys promise soft magnetic materials for industrial applications.

  12. Relatively rapid emplacement of dome-forming magma inferred from strain analyses: The case of the acid Latian dome complexes (Central Italy)

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; de Rita, D.

    2006-11-01

    We have analysed the relationship between the volcanic substratum and magma body emplacement for the acid dome complexes of Latium, Central Italy. Our study shows that the volcanic edifices, which are mainly Pleistocene cryptodomes and related explosive products, were derived from mantle magmas contaminated by crustal materials. The Cimini, Tolfa and Cerite-Manziate dome complexes of Latium show the following characteristics: a shallow laccolith origin; emplacement in basins that have identical tectonic evolution and geological structure; the same magmatic composition and density contrast between magma and host rock; and geochronological data that are inconsistent with field evidence. In the Cimini and Tolfa dome complexes, the deformation induced by shallow intrusions was accompanied by ˜ 200 m uplift of the sedimentary cover. The estimated pluton infilling time for the Cimini and Tolfa domes is 10 2 years while the strain rate required to uplift their Pliocene overburden by 200 m is ɛm' ˜ 10 - 9 s - 1 . The rapid evolution of the dome complexes is consistent with field data that show no relevant interruptions in the volcanic activity and no significant compositional changes in the volcanic products related to the extrusion of the domes. For the Cerite-Manziate dome complex, the minimal input rate of magma favoured a monogenetic style of volcanism, independent of the regional stress conditions.

  13. Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido —Contact between high-energy physics and volcano physics—

    PubMed Central

    TANAKA, Hiroyuki K. M.; YOKOYAMA, Izumi

    2008-01-01

    Lava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, “pseudo growth curves” of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the “density length” of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics. PMID:18941290

  14. Carbon nanotube fiber spun from wetted ribbon

    DOEpatents

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  15. Magma ascent dynamic through Ti diffusion in magnetites. Application to lava dome-forming eruptions. Implications to lava dome superifical explosivity.

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Morgan, Dan J.

    2016-04-01

    Superficial lava dome explosivity represents a major hazard during lava dome growth. But the origin of this explosive activity remains unclear until recently. By using geochemical (residual water content, silica abundance) and textural (vesicularity, microcristallinity) data, we constrain the occurrence of such hazard to the beginning of the lava dome activity. During the first stages of growth, the lava dome is small enough to develop an impermeable carapace that isolates a less degassed batch of magma inside, thus allowing an internal overpressurization of the volcano (Boudon et al., 2015). This study more precisely details the petrology and the texture of titano-magnetites as archive of magma ascent dynamic within the conduit. Titano-magnetites may exhibit two types of textures: exsolved or "limpid". When they are exsolved, no time constrain may be extracted as they re-equilibrate. On the contrary, when they are unexsolved, major element distribution, in particular Ti, may act as a powerful tool to decipher magma dynamic (differentiation, mixing) and estimate time that corresponds to the magma ascent time. The composition and elemental diffusion profiles are acquired by EPMA, following textural investigations by SEM. The time is then obtained by modelling the profile as a diffusion profile using the intracristalline diffusion coefficients published in literature. We applied this methodology to examples of lava dome superficial explosivity on Montagne Pelée in Martinique (Lesser Antilles Arc), and on Puy Chopine volcano in La Chaine des Puys, (French Massif Central). More precisely, the first phase of the Puy Chopine lava dome growth experienced a superficial explosion, as for Montagne Pelée, the first stages of the 1902 eruption (several superficial explosions occurred) and the 650 y. BP eruption (two superficial explosions destroyed the growing lava dome). We show that, for a single event, the vesiculated, undegassed batch of magma responsible of the

  16. Dome Schools.

    ERIC Educational Resources Information Center

    Cirulli, Carol

    1999-01-01

    Back in 1988, Emmett, Idaho, built the first monolithic dome school. Now, school boards in Arizona, Missouri, Florida, Minnesota, and New Mexico are among those that have voted to build domed school buildings. A monolithic dome is a steel- reinforced, concrete structure with a smooth, round surface that is inspired by the shape of an egg. (MLF)

  17. Correlation of Fracture Behavior With Microstructure in Friction Stir Welded, and Spin Formed AI-Li 2195 Domes

    NASA Technical Reports Server (NTRS)

    Tayon, Wesley A.; Domack, Marcia S.; Hales, Stephen J.

    2012-01-01

    Single-piece, spin-formed domes manufactured from friction stir welded (FSW) plates of Al-Li alloy 2195 have the potential to reduce the cost of fabricating cryogenic propellant tanks. Mechanical properties in the completed domes can be related directly to the final material condition and the microstructures developed. However, these new fabrication techniques have resulted in unexpected material challenges, such as abnormal grain growth in the weld nugget and the propensity for fracture in the adjacent thermo-mechanically affected zone (TMAZ). In this study, the microstructure and texture transformations within the TMAZ are related to fracture location in the vicinity of the weldment. The texture variations in the TMAZ are caused primarily by the varying amounts of shear deformation introduced during the FSW process. Grain morphology and microtexture characteristics are examined as a function of location in the TMAZ via electron backscatter diffraction (EBSD). A strong correlation between fracture location and the presence of texture banding in the TMAZ is observed. The fracture path tends to follow a distinct region of low Taylor Factor (TF) grains.

  18. Schlieren-bound Magmatic Structures Formed by the Unmixing of Granitic Magmas: A Case Study from Pothole Dome, Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Ardill, K. E.; Paterson, S. R.; Memeti, V.

    2015-12-01

    There is ongoing debate regarding the mobility of crystal mush zones in granitic magmas and their ability to mix and interact with intrusive batches to form compositional heterogeneity in plutons. Magmatic structures, localized zones of compositional diversity, enable evaluation of the significance of magmatic flow and convection vs. chemical diffusion in magmatic systems by determining their mode of formation. With further study, magmatic structures are potentially powerful tools recording syn-emplacement tectonic activity. Pothole Dome, in the Cathedral Peak Granodiorite of the Tuolumne Intrusive Complex is an ideal location to investigate magmatic structures since a variety of plumes, pipes, mafic ellipsoids, and schlieren troughs are densely clustered. Previous workers have established patterns in the orientations of different Pothole Dome magmatic structures that are indicative of a broad pattern of movement and younging directions at the kilometer scale. Preliminary whole-rock geochemical and isotopic data compare variations between the normal Cathedral magmas and a plume, trough, tube, potassium feldspar cluster and granitic dyke to investigate plausible mechanisms for the formation of the distinct compositional diversity formed in the structures. Schlieren, abundant in biotite, hornblende, apatite, sphene and zircon show relatively high levels of titanium, calcium and magnesium relative to the feldspar cluster and dyke. Schlieren are also enriched in minor elements including Zr, Y, Sr and Ce relative to the felsic structures. Both elemental and isotopic data for schlieren defining the plumes and troughs and the late leucogranitic dikes and k-feldspar clusters all plot outside the typical mixing line for Cathedral Peak Granodiorite compositions. We postulate that this may be a result of an unmixing process during physical flow of previously mixed populations of chemically distinct crystals in the Cathedral Peak.

  19. Robotic Manufacturing of 5.5 Meter Cryogenic Fuel Tank Dome Assemblies for the NASA Ares I Rocket

    NASA Technical Reports Server (NTRS)

    Jones, Ronald E.

    2012-01-01

    The Ares I rocket is the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration's (NASA's) Constellation program. A series of full-scale Ares I development articles have been constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7-axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This presentation will focus on the friction stir welding of 5.5m diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome (LH2 MDA), the common bulkhead manufacturing development articles (CBMDA) and the thermal protection system demonstration dome (TPS Dome). The LH2 MDA was the first full-scale, flight-like Ares I hardware produced under the Constellation Program. It is a 5.5m diameter elliptical dome assembly consisting of eight gore panels, a y-ring stiffener and a manhole fitting. All components are made from aluminumlithium alloy 2195. Conventional and self-reacting friction stir welding was used on this article. An overview of the manufacturing processes will be discussed. The LH2 MDA is the first known fully friction stir welded dome ever produced. The completion of four Common Bulkhead Manufacturing Development Articles (CBMDA) and the TPS Dome will also be highlighted. Each CBMDA and the TPS Dome consists of a 5.5m diameter spun-formed dome friction stir welded to a y-ring stiffener. The domes and y-rings are made of aluminum 2014 and 2219 respectively. The TPS Dome has an additional aluminum alloy 2195 barrel section welded to the y-ring. Manufacturing solutions will be discussed including "fixtureless" welding with self reacting friction stir welding.

  20. Effect of chemical treatments on flax fibre reinforced polypropylene composites on tensile and dome forming behaviour.

    PubMed

    Wang, Wentian; Lowe, Adrian; Kalyanasundaram, Shankar

    2015-03-17

    Tensile tests were performed on two different natural fibre composites (same constituent material, similar fibre fraction and thickness but different weave structure) to determine changes in mechanical properties caused by various aqueous chemical treatments and whether any permanent changes remain on drying. Scanning electronic microscopic examinations suggested that flax fibres and the flax/polypropylene interface were affected by the treatments resulting in tensile property variations. The ductility of natural fibre composites was improved significantly under wet condition and mechanical properties (elongation-to-failure, stiffness and strength) can almost retain back to pre-treated levels when dried from wet condition. Preheating is usually required to improve the formability of material in rapid forming, and the chemical treatments performed in this study were far more effective than preheating. The major breakthrough in improving the formability of natural fibre composites can aid in rapid forming of this class of material system.

  1. Effect of Chemical Treatments on Flax Fibre Reinforced Polypropylene Composites on Tensile and Dome Forming Behaviour

    PubMed Central

    Wang, Wentian; Lowe, Adrian; Kalyanasundaram, Shankar

    2015-01-01

    Tensile tests were performed on two different natural fibre composites (same constituent material, similar fibre fraction and thickness but different weave structure) to determine changes in mechanical properties caused by various aqueous chemical treatments and whether any permanent changes remain on drying. Scanning electronic microscopic examinations suggested that flax fibres and the flax/polypropylene interface were affected by the treatments resulting in tensile property variations. The ductility of natural fibre composites was improved significantly under wet condition and mechanical properties (elongation-to-failure, stiffness and strength) can almost retain back to pre-treated levels when dried from wet condition. Preheating is usually required to improve the formability of material in rapid forming, and the chemical treatments performed in this study were far more effective than preheating. The major breakthrough in improving the formability of natural fibre composites can aid in rapid forming of this class of material system. PMID:25789505

  2. Contact mechanics models and algorithms for dome polishing with UltraForm Finishing (UFF)

    NASA Astrophysics Data System (ADS)

    Bouvier, Christophe; Gracewski, Sheryl M.; Burns, Stephen J.

    2007-04-01

    UltraForm Finishing (UFF) is a new deterministic subaperture computer numerically controlled (CNC) polisher. Because UFF uses compliant tools with large contact patches, the depth of removal is prescribed by adjusting the tool crossfeed velocity. The equations for the depth of removal as the tool traverses an axisymmetric part are derived. The form correction problem consists in solving these equations by adjusting the tool crossfeed velocity to achieve a desired removal profile. The solution must satisfy constraints on the tool velocity and acceleration. Solutions for flats, spheres and aspheres are achieved by treating the problem as a constrained optimization after writing the depth of removal equations in matrix form. The solutions were validated experimentally. The removal function is evaluated by making a removal spot for one set of process parameters. Its variations, as a function of the process parameters, are predicted by using Hertz contact theory and the Preston equation. To prevent tool-part collisions and to analyze part and spot measurements, algorithms were developed for the tool path and evaluation of metrology inputs.

  3. Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica

    NASA Astrophysics Data System (ADS)

    Picard, G.; Royer, A.; Arnaud, L.; Fily, M.

    2014-06-01

    Space-borne passive microwave radiometers are widely used to retrieve information in snowy regions by exploiting the high sensitivity of microwave emission to snow properties. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this paper, we investigate the spatial variations of brightness temperature over a range of a few kilometers in the Dome C area. Using ground-based radiometers towed by a vehicle, we collected brightness temperature at 11, 19 and 37 GHz at horizontal and vertical polarizations along transects with meter resolution. The most remarkable observation was a series of regular undulations of the signal with a significant amplitude reaching 10 K at 37 GHz and a quasi-period of 30-50 m. In contrast, the variability at longer length scales seemed to be weak in the investigated area, and the mean brightness temperature was close to SSM/I and WindSat satellite observations for all the frequencies and polarizations. To establish a link between the snow characteristics and the microwave emission undulations, we collected detailed snow grain size and density profiles at two points where opposite extrema of brightness temperature were observed. Numerical simulations with the DMRT-ML microwave emission model revealed that the difference in density in the upper first meter explained most of the brightness temperature variations. In addition, we found that these variations of density near the surface were linked to snow hardness. Patches of hard snow - probably formed by wind compaction - were clearly visible and covered as much as 39% of the investigated area. Their brightness temperature was higher than in normal areas. This result implies that the microwave emission measured by satellites over Dome C is more complex than expected and very likely depends on

  4. What factors control superficial lava dome explosivity?

    PubMed Central

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoît; Morgan, Daniel J.

    2015-01-01

    Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite precipitation. Both processes generate an impermeable and rigid carapace allowing overpressurisation of the inner parts of the lava dome by the rapid input of vesiculated magma batches. The relative thickness of the cristobalite-rich carapace is an inverse function of the external lava dome surface area. Explosive activity is thus more likely to occur at the onset of lava dome extrusion, in agreement with observations, as the likelihood of superficial lava dome explosions depends inversely on lava dome volume. This new result is of interest for the whole volcanological community and for risk management. PMID:26420069

  5. What factors control superficial lava dome explosivity?

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoît; Morgan, Daniel J.

    2015-09-01

    Dome-forming eruption is a frequent eruptive style and a major hazard on numerous volcanoes worldwide. Lava domes are built by slow extrusion of degassed, viscous magma and may be destroyed by gravitational collapse or explosion. The triggering of lava dome explosions is poorly understood: here we propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite precipitation. Both processes generate an impermeable and rigid carapace allowing overpressurisation of the inner parts of the lava dome by the rapid input of vesiculated magma batches. The relative thickness of the cristobalite-rich carapace is an inverse function of the external lava dome surface area. Explosive activity is thus more likely to occur at the onset of lava dome extrusion, in agreement with observations, as the likelihood of superficial lava dome explosions depends inversely on lava dome volume. This new result is of interest for the whole volcanological community and for risk management.

  6. Dysprosium-free melt-spun permanent magnets.

    PubMed

    Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

    2014-02-12

    Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

  7. Microstructure and stability of melt spun INCONEL 713 LC

    NASA Technical Reports Server (NTRS)

    Antolovich, S. D.; Bowman, R. R.

    1986-01-01

    The alloy IN-714LC was used in an investigation of the effect of process parameters on the microstructure of a rapidly solidified melt-spun material. The resultant ribbon microstructure consisted of several distinct regions, each of which corresponds to a different thermal history during processing. A chill zone of equiaxed randomly-oriented grains exists in a region of the foil which was in contact with the wheel during casting. This zone develops into a dendritic growth morphology with distance away from the lower ribbon surface. Dendrites inclined in the direction of wheel rotation result from growth into a flowing stream. TEM studies showed that a cell structure formed, the cell size decreasing with increasing wheel speed. Aging studies indicated that the cell structure plays an important role in gamma prime precipitation. Results relating to heat treatments (as would be encountered in compaction and use) and the stability of the melt-spun structure are considered.

  8. A Radar Survey of Lunar Dome Fields

    NASA Technical Reports Server (NTRS)

    Carter, Lynn M.; Campbell, Bruce A.; Hawke, B. Ray; Bussey, Ben

    2011-01-01

    The near side of the Moon has several areas with a high concentration of volcanic domes. These low relief structures are considerably different in morphology from terrestrial cinder cones, and some of the domes may be similar to some terrestrial shields formed through Hawaiian or Strombolian eruptions from a central pipe vent or small fissure [1]. The domes are evidence that some volcanic lavas were more viscous than the mare flood basalts that make up most of the lunar volcanic flows. It is still not known what types of volcanism lead to the creation of specific domes, or how much dome formation may have varied across the Moon. Prior work has shown that some domes have unusual radar polarization characteristics that may indicate a surface or subsurface structure that is different from that of other domes. Such differences might result from different styles of late-stage volcanism for some of the domes, or possibly from differences in how the erupted materials were altered over time (e.g. by subsequent volcanism or nearby cratering events). For example, many of the domes in the Marius Hills region have high circular polarization ratios (CPRs) in S-band (12.6 cm wavelength) and/or P-band (70 cm wavelength) radar data [2]. The high CPRs are indicative of rough surfaces, and suggest that these domes may have been built from overlapping blocky flows that in some cases have been covered by meters of regolith [2, 3]. In other cases, domes have low circular polarization ratios indicative of smooth, rock-poor surfaces or possibly pyroclastics. The 12 km diameter dome Manilius 1 in Mare Vaporum [1], has a CPR value of 0.20, which is significantly below values for the surrounding basalts [4]. To better understand the range of surface properties and styles of volcanism associated with the lunar domes, we are currently surveying lunar dome fields including the Marius Hills, Cauchy/Jansen dome field, the Gruithuisen domes, and domes near Hortensius and Vitruvius.

  9. Manufacturing of 5.5 Meter Diameter Cryogenic Fuel Tank Domes for the NASA Ares I Rocket

    NASA Technical Reports Server (NTRS)

    Jones, Ronald E.; Carter, Robert W.

    2012-01-01

    The Ares I rocket is the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration s (NASA s) Constellation program. A series of full-scale Ares I development articles have been constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7-axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This presentation will focus on the friction stir welding of 5.5m diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome (LH2 MDA) and the common bulkhead manufacturing development articles (CBMDA). The LH2 MDA was the first full-scale, flight-like Ares I hardware produced under the Constellation Program. It is a 5.5m diameter elliptical dome assembly consisting of eight gore panels, a y-ring stiffener and a manhole fitting. All components are made from aluminum-lithium alloy 2195. Conventional and self-reacting friction stir welding was used on this article. Manufacturing solutions will be discussed including the implementation of photogrammetry, an advanced metrology technique, as well as fixtureless welding. The LH2 MDA is the first known fully friction stir welded dome ever produced. The completion of four Common Bulkhead Manufacturing Development Articles (CBMDA) will also be highlighted. Each CBMDA consists of a 5.5m diameter spun-formed dome friction stir welded to a y-ring stiffener. The domes and y-rings are made of aluminum 2014 and 2219 respectively. An overview of CBMDA manufacturing processes and the effect of tooling on weld defect formation will be discussed.

  10. Cryovolcanic emplacement of domes on Europa

    NASA Astrophysics Data System (ADS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.

    2017-03-01

    Here we explore the hypothesis that certain domes on Europa may have been produced by the extrusion of viscous cryolavas. A new mathematical method for the emplacement and relaxation of viscous lava domes is presented and applied to putative cryovolcanic domes on Europa. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry, and dome relaxation is explored assuming a volume of cryolava has been rapidly emplaced onto the surface. Nonphysical singularities inherent in previous models for dome relaxation have been eliminated, and cryolava cooling is represented by a time-variable viscosity. We find that at the onset of relaxation, bulk kinematic viscosities may lie in the range between 103 and 106 m2/s, while the actual fluid lava viscosity may be much lower. Plausible relaxation times to form the domes, which are linked to bulk cryolava rheology, are found to range from 3.6 days to 7.5 years. We find that cooling of the cryolava, while dominated by conduction through an icy skin, should not prevent fluids from advancing and relaxing to form domes within the timescales considered. Determining the range of emplacement conditions for putative cryolava domes will shed light on Europa's resurfacing history. In addition, the rheologies and compositions of erupted cryolavas have implications for subsurface cryomagma ascent and local surface stress conditions on Europa.

  11. Cryovolcanic Emplacement of Domes on Europa

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.

    2016-01-01

    Here we explore the hypothesis that certain domes on Europa may have been produced by the extrusion of viscous cryolavas. A new mathematical method for the emplacement and relaxation of viscous lava domes is presented and applied to putative cryovolcanic domes on Europa. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry, and dome relaxation is explored assuming a volume of cryolava has been rapidly emplaced onto the surface. Nonphysical sin- gularities inherent in previous models for dome relaxation have been eliminated, and cryolava cooling is represented by a time-variable viscosity. We find that at the onset of relaxation, bulk kinematic viscosities may lie in the range between 10(exp 3) and 10(exp 6) sq m/s, while the actual fluid lava viscosity may be much lower. Plausible relaxation times to form the domes, which are linked to bulk cryolava rheology, are found to range from 3.6 days to 7.5 years. We find that cooling of the cryolava, while dominated by conduction through an icy skin, should not prevent fluids from advancing and relaxing to form domes within the timescales considered. Determining the range of emplacement conditions for putative cryolava domes will shed light on Europa's resurfacing history. In addition, the rheologies and compositions of erupted cryolavas have implications for subsurface cryomagma ascent and local surface stress conditions on Europa.

  12. Nano/micro electro-spun polyethylene terephthalate fibrous mat preparation and characterization.

    PubMed

    Hadjizadeh, Afra; Ajji, Abdellah; Bureau, Martin N

    2011-04-01

    Electro-spun polyethylene terephthalate (PET) fibrous mats are potential substrates for biotechnological and biomedical applications. In this regard, substrate characteristics including, fiber diameter, orientation and mechanical properties play an important role in controlling the interaction of substrate with biological entities. However, few studies reporting the preparation of electro-spun PET substrates with such controlled characteristics have been published. In this study, electro-spun PET fibrous mats with fiber diameters in the nanometer and micrometer range were produced by varying polymer solution concentration and flow rate. Fiber orientation within the mats was also varied by varying collector surface velocities in rotation and translation. Their morphological, mechanical, thermal and structural properties were evaluated as a function of fiber diameter and collector speed using scanning electron microscopy (SEM), a micromechanical tester, differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. Varying polymer solution concentration and flow rate allowed the production of matrices with fiber diameters ranging from 400 nm to 2 μm. Tensile properties increased with fiber diameter and collector surface velocity. Thermal properties of electro-spun PET fibers were different from the structure of as received raw PET in the form of pellets, revealing an amorphous structure for the entire electro-spun PET. This was also confirmed by XRD analysis. No considerable differences were observed between electro-spun PET fibers, in terms of crystalline and thermal properties, produced under various conditions. These electro-spun mats with different fiber diameters, orientation and mechanical properties can be used for various applications including tissue engineering scaffolds.

  13. Radar Observations of Nearside Lunar Domes

    NASA Astrophysics Data System (ADS)

    Carter, Lynn M.; Campbell, B. A.; Hawke, B. R.; Campbell, D. B.; Nolan, M. C.; Anderson, R. F.; Wells, K. S.

    2009-09-01

    Lunar domes display a broad range of sizes, surface textures, and morphologies. Some domes are thought to have formed via extrusive volcanism originating from a central vent or rift, while others are thought to have formed through non-extrusive processes (Head and Gifford, Moon and Plan., 22, 235,1980). Recent high-resolution (80 m/pixel) S-band (12.6 cm wavelength) radar data obtained using Arecibo Observatory and the Green Bank Telescope can be used to investigate the surface properties of the different classes of lunar domes. The domes Manilus 1 and Mons Rümker (Carter et al., JGR, submitted, 2009; Campbell et al., JGR, 114, E01001, doi:10.1029/2008JE003253, 2009) have low circular polarization ratio values that may indicate the presence of pyroclastics. Other domes in the Mare Vaporum region have polarization characteristics that are similar to surrounding mare basalts (Carter et al. JGR, submitted, 2009). Our current radar data include areas with significant dome concentrations in the Mare Vaporum, Marius Hills, and Rimae Cauchy regions. We present preliminary results comparing the radar polarization properties of different dome types and discuss possible implications for their surface properties and evolution.

  14. Emplacement Scenarios for Volcanic Domes on Venus

    NASA Technical Reports Server (NTRS)

    Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.

    2012-01-01

    One key to understanding the history of resurfacing on Venus is better constraints on the emplacement timescales for the range of volcanic features visible on the surface. A figure shows a Magellan radar image and topography for a putative lava dome on Venus. 175 such domes have been identified with diameters ranging from 19 - 94 km, and estimated thicknesses as great as 4 km. These domes are thought to be volcanic in origin and to have formed by the flow of viscous fluid (i.e., lava) on the surface.

  15. Gravity spun polycaprolactone fibres for soft tissue engineering: interaction with fibroblasts and myoblasts in cell culture.

    PubMed

    Williamson, Matthew Richard; Adams, Eric F; Coombes, Allan G A

    2006-03-01

    Poly(epsilon-caprolactone) (PCL) fibres were produced by wet spinning from solutions in acetone under low shear (gravity flow) conditions. As-spun PCL fibres exhibited a mean strength and stiffness of 7.9 MPa and 0.1 GPa, respectively and a rough, porous surface morphology. Cold drawing to an extension of 500% resulted in increases in fibre strength (43 MPa) and stiffness (0.3 GPa) and development of an oriented, fibrillar surface texture. The proliferation rate of Swiss 3T3 mouse fibroblasts and C2C12 mouse myoblasts on as-spun, 500% cold-drawn and gelatin-modified PCL fibres was determined in cell culture to provide a basic measure of the biocompatibility of the fibres. Proliferation of both cell types was consistently higher on gelatin-coated fibres relative to as-spun fibres at time points below 7 days. Fibroblast growth rates on cold-drawn PCL fibres exceeded those on as-spun fibres but myoblast proliferation was similar on both substrates. After 1 day in culture, both cell types had spread and coalesced on the fibres to form a cell layer, which conformed closely to the underlying topography. The high fibre compliance combined with a potential for modifying the fibre surface chemistry with cell adhesion molecules and the surface architecture by cold drawing to enhance proliferation of fibroblasts and myoblasts, recommends further investigation of gravity-spun PCL fibres for 3-D scaffold production in soft tissue engineering.

  16. Modular combustor dome

    NASA Technical Reports Server (NTRS)

    Glynn, Christopher Charles (Inventor); Halila, Ely Eskenazi (Inventor); Bibler, John David (Inventor); Morris, David Byron (Inventor)

    2001-01-01

    A combustor dome module includes a mixer tube having a hollow heat shield sealingly joined around the outlet end thereof. The modules may then be assembled in an array for defining the combustor dome, with each module being individually removable therefrom.

  17. Fast foldable tent domes

    NASA Astrophysics Data System (ADS)

    Jägers, Aswin P. L.; Sliepen, Guus; Bettonvil, Felix C. M.; Hammerschlag, Robert H.

    2008-07-01

    In the near future ELTs (Extreme Large Telescopes) will be built. Preferably these telescopes should operate without obstructions in the near surrounding to reach optimal seeing conditions and avoid large turbulences with wind-gust accelerations around large obstacles. This applies also to future large solar telescopes. At present two foldable dome prototypes have been built on the Canary Islands: the Dutch Open Telescope (DOT, La Palma) and the GREGOR Telescope (Tenerife), having a diameter of 7 and 9 meter, respectively. The domes are usually fully retracted during observations. The research consists of measurements on the two domes. New camera systems are developed and placed inside the domes for precise dome deformation measurements within 0.1 mm over the whole dome size. Simultaneously, a variety of wind-speed and -direction sensors measure the wind field around the dome. In addition, fast sensitive air-pressure sensors placed on the supporting bows measure the wind pressure. The aim is to predict accurately the expected forces and deformations on up-scaled, fully retractable domes to make their construction more economically. The dimensions of 7 and 9 meter are large enough for realistic on-site tests in gusty wind and will give much more information than wind tunnel experiments.

  18. What factors control the superficial lava dome explosivity?

    NASA Astrophysics Data System (ADS)

    Boudon, Georges; Balcone-Boissard, Hélène; Villemant, Benoit; Morgan, Daniel J.

    2015-04-01

    Dome-forming eruption is a frequent eruptive style; lava domes result from intermittent, slow extrusion of viscous lava. Most dome-forming eruptions produce highly microcrystallized and highly- to almost totally-degassed magmas which have a low explosive potential. During lava dome growth, recurrent collapses of unstable parts are the main destructive process of the lava dome, generating concentrated pyroclastic density currents (C-PDC) channelized in valleys. These C-PDC have a high, but localized, damage potential that largely depends on the collapsed volume. Sometimes, a dilute ash cloud surge develops at the top of the concentrated flow with an increased destructive effect because it may overflow ridges and affect larger areas. In some cases, large lava dome collapses can induce a depressurization of the magma within the conduit, leading to vulcanian explosions. By contrast, violent, laterally directed, explosions may occur at the base of a growing lava dome: this activity generates dilute and turbulent, highly-destructive, pyroclastic density currents (D-PDC), with a high velocity and propagation poorly dependent on the topography. Numerous studies on lava dome behaviors exist, but the triggering of lava dome explosions is poorly understood. Here, seven dome-forming eruptions are investigated: in the Lesser Antilles arc: Montagne Pelée, Martinique (1902-1905, 1929-1932 and 650 y. BP eruptions), Soufrière Hills, Montserrat; in Guatemala, Santiaguito (1929 eruption); in La Chaîne des Puys, France (Puy de Dome and Puy Chopine eruptions). We propose a new model of superficial lava-dome explosivity based upon a textural and geochemical study (vesicularity, microcrystallinity, cristobalite distribution, residual water contents, crystal transit times) of clasts produced by these key eruptions. Superficial explosion of a growing lava dome may be promoted through porosity reduction caused by both vesicle flattening due to gas escape and syn-eruptive cristobalite

  19. The pre-eruptive magma plumbing system of the 2007-2008 dome-forming eruption of Kelut volcano, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Jeffery, A. J.; Gertisser, R.; Troll, V. R.; Jolis, E. M.; Dahren, B.; Harris, C.; Tindle, A. G.; Preece, K.; O'Driscoll, B.; Humaida, H.; Chadwick, J. P.

    2013-07-01

    Kelut volcano, East Java, is an active volcanic complex hosting a summit crater lake that has been the source of some of Indonesia's most destructive lahars. In November 2007, an effusive eruption lasting approximately 7 months led to the formation of a 260-m-high and 400-m-wide lava dome that displaced most of the crater lake. The 2007-2008 Kelut dome comprises crystal-rich basaltic andesite with a texturally complex crystal cargo of strongly zoned and in part resorbed plagioclase (An47-94), orthopyroxene (En64-72, Fs24-32, Wo2-4), clinopyroxene (En40-48, Fs14-19, Wo34-46), Ti-magnetite (Usp16-34) and trace amounts of apatite, as well as ubiquitous glomerocrysts of varying magmatic mineral assemblages. In addition, the notable occurrence of magmatic and crustal xenoliths (meta-basalts, amphibole-bearing cumulates, and skarn-type calc-silicates and meta-volcaniclastic rocks) is a distinct feature of the dome. New petrographical, whole rock major and trace element data, mineral chemistry as well as oxygen isotope data for both whole rocks and minerals indicate a complex regime of magma-mixing, decompression-driven resorption, degassing and crystallisation and crustal assimilation within the Kelut plumbing system prior to extrusion of the dome. Detailed investigation of plagioclase textures alongside crystal size distribution analyses provide evidence for magma mixing as a major pre-eruptive process that blends multiple crystal cargoes together. Distinct magma storage zones are postulated, with a deeper zone at lower crustal levels or near the crust-mantle boundary (>15 km depth), a second zone at mid-crustal levels (~10 km depth) and several magma storage zones distributed throughout the uppermost crust (<10 km depth). Plagioclase-melt and amphibole hygrometry indicate magmatic H2O contents ranging from ~8.1 to 8.6 wt.% in the lower crustal system to ~1.5 to 3.3 wt.% in the mid to upper crust. Pyroxene and plagioclase δ18O values range from 5.4 to 6.7 ‰, and 6

  20. Optical Measurements On Advanced Performance Domes

    NASA Astrophysics Data System (ADS)

    Archibald, P. C.; Burge, D. K.

    1984-12-01

    Sapphire, spinel, and ALON (aluminum oxynitride) have been identified as candidate dome materials for ultraviolet through 5 μm wavelength applications. They possess optical, mechanical, and thermal properties that are superior to those of currently used Irtran-1 domes. Optical performance of these materials in the visible wavelength region far exceeds that of Irtran-1, while infrared properties reported here vary from worse than to better than Irtran-1 domes. Reported in this paper are measurements of optical scatter and transmittance at 0.4762, 0.6471, and 3.39 μm, which represent a large range of values obtained on these materials in dome form. Processing changes over the last few years have produced improvements in both scatter and transmittance, provided that a good surface finish is maintained. Higher index of refraction will, of course, limit the ultimate transmittance for uncoated domes of these materials to slightly less than that of Irtran-1, which has also improved in the same time period. Calculations indicate maximum transmittance at 3.39 pm to be 0.95 to 0.96 for Irtran-1 and 0.87 to 0.88 for spinel, a difference of 0.08. Current measurements at the Naval Weapons Center confirm values of 0.88 for spinel, while the best Irtran-1 dome gave a value of less than 0.92.

  1. In-situ Microwave Brightness Temperature Variability from Ground-based Radiometer Measurements at Dome C in Antarctica Induced by Wind-formed Features

    NASA Technical Reports Server (NTRS)

    Royer, A.; Picard, G.; Arnaud, L.; Brucker, L.; Fily, M..

    2014-01-01

    Space-borne microwave radiometers are among the most useful tools to study snow and to collect information on the Antarctic climate. They have several advantages over other remote sensing techniques: high sensitivity to snow properties of interest (temperature, grain size, density), subdaily coverage in the polar regions, and their observations are independent of cloud conditions and solar illumination. Thus, microwave radiometers are widely used to retrieve information over snow-covered regions. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this presentation, we investigate the spatial variations of brightness temperature over arange of a few kilometers in the Dome C area (Antarctic Plateau).

  2. Dry-Spun Silk Produces Native-Like Fibroin Solutions

    PubMed Central

    2016-01-01

    Silk’s outstanding mechanical properties and energy efficient solidification mechanisms provide inspiration for biomaterial self-assembly as well as offering a diverse platform of materials suitable for many biotechnology applications. Experiments now reveal that the mulberry silkworm Bombyx mori secretes its silk in a practically “unspun” state that retains much of the solvent water and exhibits a surprisingly low degree of molecular order (β-sheet crystallinity) compared to the state found in a fully formed and matured fiber. These new observations challenge the general understanding of silk spinning and in particular the role of the spinning duct for structure development. Building on this discovery we report that silk spun in low humidity appears to arrest a molecular annealing process crucial for β-sheet formation. This, in turn, has significant positive implications, enabling the production of a high fidelity reconstituted silk fibroin with properties akin to the gold standard of unspun native silk. PMID:27526078

  3. Pancakelike domes on Venus

    NASA Technical Reports Server (NTRS)

    Mckenzie, Dan; Ford, Peter G.; Liu, Fang; Pettengill, Gordon H.

    1992-01-01

    The shape of seven large domes on the plains of Venus, with volumes between 100 and 1000 cu km, is compared with that of an axisymmetric gravity current spreading over a rigid horizontal surface. Both the altimetric profiles and the horizontal projection of the line of intersection of domes on the SAR images agree well with the theoretical similarity solution for a newtonian fluid, but not with the shape calculated for a rigid-plastic rheology, nor with that for a static model with a strong skin. As a viscous current spreads, it generates an isotropic strain rate tensor whose magnitude is independent of radius. Such a flow can account for the randomly oriented cracks that are uniformly distributed on the surface of the domes. The stress induced by the flow in the plains material below is obtained, and is probably large enough to produce the short radial cracks in the surface of the plains beyond the domes. The viscosity of the domes can be estimated from their thermal time constants if spreading is possible only when the fluid is hot, and lies between 10(exp 14) and 10(exp 17) Pa s. Laboratory experiments show that such viscosities correspond to temperatures of 610 - 690 C in dry rhyolitic magmas. These temperatures agree with laboratory measurements of the solidus temperature of wet rhyolite. These results show that the development of the domes can be understood using simple fluid dynamical ideas, and that the magmas involved can be produced by wet melting at depths below 10 km, followed by eruption and degassing.

  4. A Volume Flux Approach to Cryolava Dome Emplacement on Europa

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Fagents, Sarah A.; Hurford, Terry A.; Prockter, Louise M.

    2017-01-01

    We previously modeled a subset of domes on Europa with morphologies consistent with emplacement by viscous extrusions of cryolava. These models assumed instantaneous emplacement of a fixed volume of fluid onto the surface, followed by relaxation to form domes. However, this approach only allowed for the investigation of late-stage eruptive processes far from the vent and provided little insight into how cryolavas arrived at the surface. Consideration of dome emplacement as cryolavas erupt at the surface is therefore pertinent. A volume flux approach, in which lava erupts from the vent at a constant rate, was successfully applied to the formation of steep-sided volcanic domes on Venus. These domes are believed to have formed in the same manner as candi-date cryolava domes on Europa. In order to gain a more complete understanding of the potential for the emplacement of Europa domes via extrusive volcanism, we have applied this new volume flux approach to the formation of putative cryovolcanic domes on Europa. Assuming as in that europan cryolavas are briny, aqueous solutions which may or may not contain some ice crystal fraction, we present the results of this modeling and explore theories for the formation of low-albedo moats that surround some domes.

  5. Rigidity of lattice domes

    NASA Technical Reports Server (NTRS)

    Savelyev, V. A.

    1979-01-01

    The means of ensuring total rigidity of lattice domes, using comparison with solid shells of 1-3 layers are discussed. Irregularities of manufacture, processing, and other factors are considered, as they relate to diminution of rigidity. The discussion uses the concepts of upper and lower critical loads on the structure in question.

  6. Steep-sided domes on Venus - Characteristics, geologic setting, and eruption conditions from Magellan data

    NASA Technical Reports Server (NTRS)

    Pavri, Betina; Head, James W., III; Klose, K. B.; Wilson, Lionel

    1992-01-01

    A survey of more than 95 percent of the Venus surface reveals 145 steep-sided domes which can be subdivided into a variety of morphologic forms, the most common being shaped like inverted bowls or flat-topped domes. Results of a preliminary analysis of the distribution and geologic setting of the domes are presented. The relation of the domes to analogous terrestrial features is examined, and possible models for their mode of emplacement are outlined.

  7. Lava flows and domes

    SciTech Connect

    Fink, J. )

    1989-01-01

    This book discusses emplacement of silicic domes and mafic lava flows. The authors have utilized the combination of field, experimental and theoretical methods to constrain various characteristics of recently-emplaced lavas, including dimensions, growth rates, surface morphology, deformation styles, rheology, and volatile contents. Filed measurements from numerous volcanoes are presented. Focus is on data from Mount St. Helens. The value of such investigations is addressed.

  8. The longevity of lava dome eruptions

    NASA Astrophysics Data System (ADS)

    Wolpert, Robert L.; Ogburn, Sarah E.; Calder, Eliza S.

    2016-02-01

    Understanding the duration of past, ongoing, and future volcanic eruptions is an important scientific goal and a key societal need. We present a new methodology for forecasting the duration of ongoing and future lava dome eruptions based on a database (DomeHaz) recently compiled by the authors. The database includes duration and composition for 177 such eruptions, with "eruption" defined as the period encompassing individual episodes of dome growth along with associated quiescent periods during which extrusion pauses but unrest continues. In a key finding, we show that probability distributions for dome eruption durations are both heavy tailed and composition dependent. We construct objective Bayesian statistical models featuring heavy-tailed Generalized Pareto distributions with composition-specific parameters to make forecasts about the durations of new and ongoing eruptions that depend on both eruption duration to date and composition. Our Bayesian predictive distributions reflect both uncertainty about model parameter values (epistemic uncertainty) and the natural variability of the geologic processes (aleatoric uncertainty). The results are illustrated by presenting likely trajectories for 14 dome-building eruptions ongoing in 2015. Full representation of the uncertainty is presented for two key eruptions, Soufriére Hills Volcano in Montserrat (10-139 years, median 35 years) and Sinabung, Indonesia (1-17 years, median 4 years). Uncertainties are high but, importantly, quantifiable. This work provides for the first time a quantitative and transferable method and rationale on which to base long-term planning decisions for lava dome-forming volcanoes, with wide potential use and transferability to forecasts of other types of eruptions and other adverse events across the geohazard spectrum.

  9. Sustainable Outreach: Lessons Learned from Space Update and Discovery Dome

    NASA Astrophysics Data System (ADS)

    Reiff, P. H.; Sumners, C.; Law, C. C.

    2009-12-01

    A sustainable program lives on past its initial funding cycle, and develops a network of users that ensures continued life, either by fees, advertising revenue, or by making the program more successful in later sponsored grants. Teachers like free things, so having a sponsor for products such as lithographs or CD-Roms is key to wide distribution. In 1994 we developed “Space Update®”, under the NASA “Public Use of the Internet” program. It has new editions annually, with over 40,000 distributed so far (many purchased but most free at teacher and student workshops). In 1996 we created a special edition “Space Weather®”, which includes the space weather module from Space Update plus other resources. Initially developed with funding from the IMAGE mission, it is now sponsored by Cluster and MMS. A new edition is published annually and distributed in the “Sun-Earth Day” packet; total distribution now exceeds 180,000. “Earth Update” was created in 1999 under cooperative agreement “Museums Teaching Planet Earth”. It now has a total distribution of over 20,000. Both Earth Update and Space Update were developed to be museum kiosk software, and more than 15 museums have them on display. Over 4,000 users are active in our e-Teacher network and 577 in our museum educator network. Although these can certainly be considered successful because of their longevity and user base, we have had a far more dramatic sustainable program arise in the last six years… the “Discovery Dome®”. Invented at HMNS and developed under NASA Cooperative Agreement “Immersive Earth”, this dome was the first digital portable planetarium that also showed fulldome movies with an interactive interface (first shown to the public at the Dec 2003 AGU meeting). The Discovery Dome network (tinyurl.com/DiscDome) has spun those initial 6 NASA-funded domes into over 90 installations in 22 states and 23 countries. Creating high quality content is quite expensive and so needs

  10. Emplacement of Volcanic Domes on Venus and Europa

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Steve M.

    2015-01-01

    Placing firmer constraints on the emplacement timescales of visible volcanic features is essential to obtaining a better understanding of the resurfacing history of Venus. Fig. 1 shows a Magellan radar image and topography for a putative venusian lava dome. 175 such domes have been identified, having diameters that range from 19 - 94 km, and estimated thicknesses as great as 4 km [1-2]. These domes are thought to be volcanic in origin [3], having formed by the flow of a viscous fluid (i.e., lava) onto the surface. Among the unanswered questions surrounding the formation of Venus steep-sided domes are their emplacement duration, composition, and the rheology of the lava. Rheologically speaking, maintenance of extremely thick, 1-4 km flows necessitates higher viscosity lavas, while the domes' smooth upper surfaces imply the presence of lower viscosity lavas [2-3]. Further, numerous quantitative issues, such as the nature and duration of lava supply, how long the conduit remained open and capable of supplying lava, the volumetric flow rate, and the role of rigid crust in influencing flow and final morphology all have implications for subsurface magma ascent and local surface stress conditions. The surface of Jupiter's icy moon Europa exhibits many putative cryovolcanic constructs [5-7], and previous workers have suggested that domical positive relief features imaged by the Galileo spacecraft may be volcanic in origin [5,7-8] (Fig. 2). Though often smaller than Venus domes, if emplaced as a viscous fluid, formation mechanisms for europan domes may be similar to those of venusian domes [7]. Models for the emplacement of venusian lava domes (e.g. [9-10]) have been previously applied to the formation of putative cryolava domes on Europa [7].

  11. The longevity of lava dome eruptions: analysis of the global DomeHaz database

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Wolpert, R.; Calder, E.; Pallister, J. S.; Wright, H. M. N.

    2015-12-01

    The likely duration of ongoing volcanic eruptions is a topic of great interest to volcanologists, volcano observatories, and communities near volcanoes. Lava dome forming eruptions can last from days to centuries, and can produce violent, difficult-to-forecast activity including vulcanian to plinian explosions and pyroclastic density currents. Periods of active dome extrusion are often interspersed with periods of relative quiescence, during which extrusion may slow or pause altogether, but persistent volcanic unrest continues. This contribution focuses on the durations of these longer-term unrest phases, hereafter eruptions, that include periods of both lava extrusion and quiescence. A new database of lava dome eruptions, DomeHaz, provides characteristics of 228 eruptions at 127 volcanoes; for which 177 have duration information. We find that while 78% of dome-forming eruptions do not continue for more than 5 years, the remainder can be very long-lived. The probability distributions of eruption durations are shown to be heavy-tailed and vary by magma composition. For this reason, eruption durations are modeled with generalized Pareto distributions whose governing parameters depend on each volcano's composition and eruption duration to date. Bayesian predictive distributions and associated uncertainties are presented for the remaining duration of ongoing eruptions of specified composition and duration to date. Forecasts of such natural events will always have large uncertainties, but the ability to quantify such uncertainty is key to effective communication with stakeholders and to mitigation of hazards. Projections are made for the remaining eruption durations of ongoing eruptions, including those at Soufrière Hills Volcano, Montserrat and Sinabung, Indonesia. This work provides a quantitative, transferable method and rationale on which to base long-term planning decisions for dome forming volcanoes of different compositions, regardless of the quality of an

  12. Mechanical properties of continuously spun fibers of carbon nanotubes.

    PubMed

    Motta, Marcelo; Li, Ya-Li; Kinloch, Ian; Windle, Alan

    2005-08-01

    We report on the mechanical properties of fibers consisting of pure carbon nanotube fibers directly spun from an aerogel formed during synthesis by chemical vapor deposition. The continuous withdrawal of product from the gas phase imparts a high commercial potential to the process, either for the production of particularly strong fibers or for the economic production of bulk quantities of carbon nanotubes. Tensile tests were performed on fibers produced from the dissociation of three different hydrocarbons, namely, ethanol, ethylene glycol, and hexane, with a range of iron (catalyst) concentrations. The conditions were chosen to lie within the range known to enable satisfactory continuous spinning, the iron concentration being varied within this range. Increasing proportions of single wall nanotubes were found as the iron concentration was decreased, conditions which also produced fibers of best strength and stiffness. The maximum tensile strength obtained was 1.46 GPa (equivalent to 0.70 N/tex assuming a density of 2.1 g/cm(3)). The experiments indicate that significant improvements in the mechanical properties can be accomplished by optimizing the process conditions.

  13. Emplacement and composition of steep-sided domes on Venus

    NASA Astrophysics Data System (ADS)

    Stofan, Ellen R.; Anderson, Steven W.; Crown, David A.; Plaut, Jeffrey J.

    2000-11-01

    Steep-sided domes on Venus have surface characteristics that can provide information on their emplacement, including relatively smooth upper surfaces, radial and polygonal fracture patterns, and pits. These characteristics indicate that domes have surface crusts which are relatively unbroken, have mobile interiors after emplacement, and preserve fractures from only late in their history in response to endogenous growth or sagging of the dome surface. We have calculated the time necessary to form a 12-cm-thick crust for basalt and rhyolite under current terrestrial and Venusian ambient conditions. A 12-cm-thick crust will form in all cases in <10 hours. Although Venusian lava flows should develop a brittle carapace during emplacement, only late-stage brittle fractures are preserved at steep-sided domes. We favor an emplacement model where early-formed surface crusts are entrained or continually annealed as they deform to accommodate dome growth. Entrainment and annealing of fractures are not mutually exclusive processes and thus may both be at work during steep-sided dome emplacement. Our results are most consistent with basaltic compositions, as rhyolitic lavas would quickly form thick crusts which would break into large blocks that would be difficult to entrain or anneal. However, if Venus has undergone large temperature excursions in the past (producing ambient conditions of 800-1000 K [e.g., Bullock and Grinspoon, 1996, 1998]), rhyolitic lavas would be unable to form crusts at high surface temperatures and could produce domes with surface characteristics consistent with those of Venusian steep-sided domes.

  14. The LSST Dome final design

    NASA Astrophysics Data System (ADS)

    DeVries, J.; Neill, D. R.; Barr, J.; De Lorenzi, Simone; Marchiori, Gianpietro

    2016-07-01

    The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the Cerro Pachón summit in Chile 1. As a result of the Telescope wide field of view, the optical system is unusually susceptible to stray light 2. In addition, balancing the effect of wind induced telescope vibrations with Dome seeing is crucial. The rotating enclosure system (Dome) includes a moving wind screen and light baffle system. All of the Dome vents include hinged light baffles, which provide exceptional Dome flushing, stray light attenuation, and allows for vent maintenance access from inside the Dome. The wind screen also functions as a light screen, and helps define a clear optical aperture for the Telescope. The Dome must operate continuously without rotational travel limits to accommodate the Telescope cadence and travel. Consequently, the Azimuth drives are located on the fixed lower enclosure to accommodate glycol water cooling without the need for a utility cable wrap. An air duct system aligns when the Dome is in its parked position, and this provides air cooling for temperature conditioning of the Dome during the daytime. A bridge crane and a series of ladders, stairs and platforms provide for the inspection, maintenance and repair of all of the Dome mechanical systems. The contract to build the Dome was awarded to European Industrial Engineering in Mestre, Italy in May 2015. In this paper, we present the final design of this telescope and site sub-system.

  15. First field identification of the Cuonadong dome in southern Tibet: implications for EW extension of the North Himalayan gneiss dome

    NASA Astrophysics Data System (ADS)

    Fu, Jiangang; Li, Guangming; Wang, Genhou; Huang, Yong; Zhang, Linkui; Dong, Suiliang; Liang, Wei

    2016-07-01

    The Cuonadong dome exposes in east-southern margin of the North Himalayan gneiss domes (NHGD), which is reported first time in this study. The Cuonadong dome is located at the southern part of the Zhaxikang ore concentration area, which is divided into three tectono-lithostratigraphic units by two curved faults around the dome geometry from upper to lower (or from outer to inner): the upper unit, middle unit and lower unit, and the outer fault is Nading fault, while the inner fault is Jisong fault. The Cuonadong dome is a magmatic orthogneiss and leucogranite mantled by orthogneiss and metasedimentary rocks, which in turn are overlain by Jurassic metasedimentary and sedimentary rocks. The grades of metamorphism and structural deformation increase towards the core, which is correspondence with the Ridang Formation low-metamorphic schist, tourmaline granitic-biotite gneiss, garnet-mica gneiss and mylonitic quartz-mica gneiss. The Cuonadong dome preserves evidences for four major deformational events: firstly top-to-S thrust (D1), early approximately N-S extensional deformation (D2), main approximately E-W extensional deformation (D3), and late collapse structural deformation (D4) around the core of the Cuonadong dome, which are consistent to three groups lineation: approximately N-S-trending lineation including L1 and L2, E-W trending L3, and L4 with plunging towards outside of the dome, respectively. The formation of the Cuonadong dome was probably resulted from the main E-W extensional deformation which is a result of eastward flow of middle or lower crust from beneath Tibet accommodated by northward oblique underthrusting of Indian crust beneath Tibet. The establishment of the Cuonadong dome enhanced the E-W extension of the NHGD, which is further divided into two structural dome zones according to the different extensional directions: approximately N-S extensional North Himalayan gneiss domes (NS-NHGD) and E-W extensional North Himalayan gneiss domes (EW

  16. The GREGOR dome, pathfinder for the EST dome

    NASA Astrophysics Data System (ADS)

    Hammerschlag, Robert H.; Kommers, Johannes N.; Visser, Simon; Bettonvil, Felix C. M.; van Schie, Anton G. M.; van Leverink, Simon J.; Sliepen, Guus; Jägers, Aswin P. L.

    2012-09-01

    The completely open-foldable dome of the GREGOR telescope is a further development of the DOT dome, respectively 9 and 7 meter in diameter. New technical developments are implemented and tested at the GREGOR dome, that are important for the design of the much larger dome for the EST, which will be 28 meter in diameter. The GREGOR dome is the first with more than one clamp working simultaneously for closing the dome and bringing the membranes on the required high tension for storm resistance. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR gave no problems nor did the storms afterwards. Opening and closing experiences are up to wind speeds of 90 km/h without problems. Good observing circumstances never occur with higher wind speeds. A double layer of membranes is applied in the GREGOR construction whereas the DOT dome is equipped with a single layer. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulation capability of this double-layer construction. The experiences with the GREGOR showed that the elongation by tensioning of the prestrained membrane material is much lower than originally expected. In the meantime, more strong and stiff membrane material is available and applied in the EST design. As a consequence, the clamps of the EST can have a relatively much shorter length and there is no need anymore for simultaneous operation of the clamps and the main actuators in low speed with help of a frequency inverter. The clamps can close after the main bow operation is finished, which simplifies the electrical control.

  17. A Dome Amidst the Hexagons

    ERIC Educational Resources Information Center

    American School and University, 1976

    1976-01-01

    Describes the design of the gymnasium of York (South Carolina) Comprehensive High School, a circular 12,000 square foot structure with a prefabricated domed roof constructed of steel hubs and curved wooden beams. (JG)

  18. Dome: Distributed Object Migration Environment

    DTIC Science & Technology

    1994-05-01

    Best Available Copy AD-A281 134 Computer Science Dome: Distributed object migration environment Adam Beguelin Erik Seligman Michael Starkey May 1994...Beguelin Erik Seligman Michael Starkey May 1994 CMU-CS-94-153 School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 Abstract Dome... Linda [4], Isis [2], and Express [6] allow a pro- grammer to treat a heterogeneous network of computers as a parallel machine. These tools allow the

  19. Estimating dome seeing for LSST

    NASA Astrophysics Data System (ADS)

    Sebag, Jacques; Vogiatzis, Konstantinos

    2014-08-01

    Begin Dome seeing is a critical effect influencing the optical performance of ground based telescopes. A previously reported combination of Computational Fluid Dynamics (CFD) and optical simulations to model dome seeing was implemented for the latest LSST enclosure geometry. To this end, high spatial resolution thermal unsteady CFD simulations were performed for three different telescope zenith angles and four azimuth angles. These simulations generate time records of refractive index values along the optical path, which are post-processed to estimate the image degradation due to dome seeing. This method allows us to derive the distribution of seeing contribution along the different optical path segments that composed the overall light path between the entrance of the dome up to the LSST science camera. These results are used to recognize potential problems and to guide the observatory design. In this paper, the modeling estimates are reviewed and assessed relative to the corresponding performance allocation, and combined with other simulator outputs to model the dome seeing impact during LSST operations.

  20. Thermal design of the Galileo spun and despun science

    NASA Technical Reports Server (NTRS)

    Greenfield, M.; Reeve, R.; Stultz, J.; Wu, P.

    1989-01-01

    The delay in the launching of the Galileo spacecraft, which was to be launched aboard the Space Shuttle Atlantis, caused by the Challenger accident resulted in a decrease in the Radioisotope Thermoelectric Generator (RTG) power. A change to the Inertial Upper Stage from the more powerful Centaur G-Prime resulted in a trajectory that requires gravity assists, once by Venus and twice by earth. The resulting peak solar intensity of this roundabout trajectory is more than twice the previous design value for the direct trajectory. The resulting changes in solar intensity range and the RTG power output were substantial and forced major thermal design changes. This paper discusses the thermal design and redesign of the Galileo Spun and Despun sciences. Data are presented on the allowable temperatures for the Spun and Despun sciences, the energy balance calculated for the Despun science, and the Despun science test results.

  1. The lunar Gruithuisen silicic extrusive domes: Topographic configuration, morphology, ages, and internal structure

    NASA Astrophysics Data System (ADS)

    Ivanov, M. A.; Head, J. W.; Bystrov, A.

    2016-07-01

    The Gruithuisen domes, situated on the western portion of the Imbrium basin rim, form three tall mountains (NW, Gamma, Delta) totaling ∼780 km3 in volume. The shapes of the domes are significantly different from that of mare-type domes elsewhere on the Moon. We use data from the Lunar Reconnaissance Orbiter (LRO) and Kaguya missions (LRO Lunar Orbiter Laser Altimeter, Lunar Reconnaissance Orbiter Camera, Diviner, and the Kaguya imager) to characterize the domes and assess models for their origin. The configuration of the domes (steep slopes, up to ∼18-20°) and their specific remote sensing characteristics (strong downturn in the UV, and results from the M3 and Diviner instruments) suggest that the domes formed by eruptions of highly viscous lava. The estimated surface volumes of the domes vary from ∼20 km3 (NW dome) to ∼290 km3 (Gamma dome) to ∼470 km3 (Delta dome). The domes occur on the portion of the Imbrium basin rim that is overlain by ejecta from the post-Imbrium Iridum crater. In some areas, relatively high albedo smooth volcanic plains are seen within the Iridum ejecta near the Gruithuisen domes, and low albedo mare deposits surround and embay the domes and Iridum crater. Dating of different units and features by crater counts indicates that impact melts from the Iridum basin are ∼3.9 Ga old, the domes Gamma and Delta are ∼3.8 Ga, and the ages of the plains near the domes vary from ∼2.3 to ∼3.6 Ga. A fresh impact crater exposes the internal structure of the Gamma dome. The most prominent features on the wall of the crater are rough, blocky layers that are typical of volcanic plains in the highlands and maria around the domes. The layers are interleaved with fine-grained materials of higher and lower albedo and the visible orientation of the layers changes over short (a few hundred meters) distances. These characteristics of the internal structure of the dome are consistent with eruptions of high viscosity lava (rough layers) that

  2. Emplacement of the final lava dome of the 2009 eruption of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Bull, Katharine F.; Anderson, Steven W.; Diefenbach, Angela K.; Wessels, Rick L.; Henton, Sarah M.

    2013-06-01

    After more than 8 months of precursory activity and over 20 explosions in 12 days, Redoubt Volcano, Alaska began to extrude the fourth and final lava dome of the 2009 eruption on April 4. By July 1 the dome had filled the pre-2009 summit crater and ceased to grow. By means of analysis and annotations of time-lapse webcam imagery, oblique-image photogrammetry techniques and capture and analysis of forward-looking infrared (FLIR) images, we tracked the volume, textural, effusive-style and temperature changes in near-real time over the entire growth period of the dome. The first month of growth (April 4-May 4) produced blocky intermediate- to high-silica andesite lava (59-62.3 wt.% SiO2) that initially formed a round dome, expanding by endogenous growth, breaking the surface crust in radial fractures and annealing them with warmer, fresh lava. On or around May 1, more finely fragmented and scoriaceous andesite lava (59.8-62.2 wt.% SiO2) began to appear at the top of the dome coincident with increased seismicity and gas emissions. The more scoriaceous lava spread radially over the dome surface, while the dome continued to expand from endogenous growth and blocky lava was exposed on the margins and south side of the dome. By mid-June the upper scoriaceous lava had covered 36% of the dome surface area. Vesicularity of the upper scoriaceous lava range from 55 to 66%, some of the highest vesicularity measurements recorded from a lava dome. We suggest that the stability of the final lava dome primarily resulted from sufficient fracturing and clearing of the conduit by preceding explosions that allowed efficient degassing of the magma during effusion. The dome was thus able to grow until it was large enough to exceed the magmastatic pressure in the chamber, effectively shutting off the eruption.

  3. Upheaval Dome, An Analogue Site for Gale Center

    NASA Technical Reports Server (NTRS)

    Conrad, P. G.; Eignebrode, J. L.

    2011-01-01

    We propose Upheaval Dome in southeastern Utah as an impact analogue site on Earth to Mars Science Laboratory candidate landing site Gale Crater. The genesis of Upheaval Dome was a mystery for some time--originally thought to be a salt dome. The 5 km crater was discovered to possess shocked quartz and other shock metamorphic features just a few years ago, compelling evidence that the crater was formed by impact, although the structural geology caused Shoemaker and Herkenhoff to speculate an impact origin some 25 years earlier. The lithology of the crater is sedimentary. The oldest rocks are exposed in the center of the dome, upper Permian sandstones, and progressively younger units are well exposed moving outward from the center. These are Triassic sandstones, siltstones and shales, which are intruded by clastic dikes. There are also other clay-rich strata down section, as is the case with Gale Crater. There is significant deformation in the center of the crater, with folding and steeply tilted beds, unlike the surrounding Canyonlands area, which is relatively undeformed. The rock units are well exposed at Upheaval Dome, and there are shatter cones, impactite fragments, shocked quartz grains and melt rocks present. The mineral shock features suggest that the grains were subjected to dynamic pressures> 10 GPa.

  4. Folding retractable protective dome for space vehicle equipment

    NASA Technical Reports Server (NTRS)

    Clark, Paul R. (Inventor); Messinger, Ross H. (Inventor)

    2008-01-01

    A folding, retractable dome for protecting a feature, such as a docking mechanism, a hatch or other equipment at an exterior surface of a space vehicle, includes a plurality of arcuate ribs, each having opposite ends respectively pinioned at opposite sides of the feature at the surface of the vehicle for rotational movement about an axis of rotation extending through the opposite ends and through an arcuate path of revolution extending over the feature, and a flexible cover attached to each of the ribs such that, in a deployed configuration of the dome, in which adjacent ribs are rotated apart from each other at a maximum relative angle therebetween, the cover is stretched generally tangentially between the adjacent ribs to form a generally arcuate shield over the feature, and in a retracted position of the dome, in which adjacent ribs are rotated together at a minimum relative angle therebetween, the cover is collapsed to define folded pleats between the adjacent ribs.

  5. Salt dome discoveries mounting in Mississippi

    SciTech Connect

    Ericksen, R.L.

    1996-06-17

    Exploratory drilling around piercement salt domes in Mississippi has met with a string of successes in recent months. Exploration of these salt features is reported to have been initiated through the review of non-proprietary, 2D seismic data and subsurface control. This preliminary data and work were then selectively upgraded by the acquisition of additional, generally higher quality, conventional 2D seismic lines. This current flurry of successful exploration and ensuing development drilling by Amerada Hess Corp. on the flanks of salt domes in Mississippi has resulted in a number of significant Hosston discoveries/producers at: Carson salt dome in Jefferson Davis County; Dry Creek salt dome in Covington County, Midway salt dome in lamar County, Monticello salt dome in Lawrence County, and Prentiss salt dome in Jefferson Davis County. The resulting production from these fields is gas and condensate, with wells being completed on 640 acre production units.

  6. Foldable dome climate measurements and thermal properties

    NASA Astrophysics Data System (ADS)

    Sliepen, Guus; Jägers, Aswin P. L.; Hammerschlag, Robert H.; Bettonvil, Felix C. M.

    2010-07-01

    As part of a larger project for measuring various aspects of foldable domes in the context of EST and with support of the Dutch Technology Foundation STW, we have collected over a year of continuous temperature and humidity measurements, both inside and outside the domes of the Dutch Open Telescope (DOT) on La Palma5 and the GREGOR telescope on Tenerife.6 In addition, we have measured the wind field around each dome. Although the structure of both domes is similar, the DOT dome has a single layer of cloth, and is situated on top of an open tower. In contrast, the GREGOR dome has a double layer of cloth, and is situated on top of a tower-shaped building. These differences result in large differences in temperature and humidity insulation when the dome is closed. We will present the changes in temperature and humidity one can expect for each dome within one day, and the statistics for the variations throughout a year. In addition, we will show that the main advantage of a foldable dome is the near instantaneous equilibration of the air inside the volume originally enclosed by the dome and that of the environment outside the dome. This property allows one to operate a telescope without needing expensive air conditioning and dome skin temperature control in order to limit dome and shell seeing effects. The measurements give also information about the weather fluctuations at the sites of the domes. It was observed that on small time scales the temperature fluctuations are significantly greater during the day than during the night.

  7. Quaternary geology of Vacherie salt dome, north Louisiana salt dome basin. Volume II

    SciTech Connect

    Kolb, C.R.; Holmes, J.C.; Alford, J.J.

    1983-07-01

    This volume comprises 14 appendices: lineations on Vacherie and Rayburn's domes (1977); possible geomorphic influence of Vacherie salt dome on the Quaternary fluvial geomorphology of Bashaway Creek (1980); remote sensing and analysis of radar imagery (1978); uphole seismic survey at Vacherie salt dome (1977); electrical resistivity survey at Vacherie salt dome (1978); pedologic investigations (1977); ionium-thorium dating of ironstones from terrace deposits, Vacherie salt dome, North Louisiana (1978); grain-shape and grain-surface studies (1981); the terrace concept - Gulf Coastal Plain (1981); interpretation of Quaternary sediments along lines of seismic shot hole (1976); topographic lows above domes (1977); structural significance of topographic lows above North Louisiana salt domes (1981); diagnostic microfossils - Vacherie dome (1978); and development of stratigraphy above Vacherie dome from Cretaceous to Sparta times (1982).

  8. Documenting deformation patterns and exhumation across Gianbul Dome, NW India

    NASA Astrophysics Data System (ADS)

    Bowman-Kamaha'o, M.; Lee, J.; Cosca, M. A.

    2012-12-01

    The channel flow model explains the development of the parallel and coeval opposing slip sense structures in the Himalayan orogeny, the southern Tibetan detachment system (STDS) and Main central thrust (MCT). In addition to predicting these two key structures, the channel flow model predicts the development of gneiss domes by several mechanisms. We tested the gneiss dome formation mechanisms by completing detailed deformation, kinematic shear sense, quartz lattice, and deformation temperature analyses, and 40Ar/39Ar thermochronology on middle crustal rocks exposed in Gianbul Dome (GD), NW India. GD comprises high Himalayan crystalline rocks with a sillimanite-grade migmatite core mantled semi-concentrically by lower metamorphic grade kyanite, staurolite, and garnet-bearing units and intruded by prominent mid-Miocene leucogranites. The northeast flank of the dome is buttressed by the Zanskar shear zone, a NE-dipping, down to the northeast normal sense shear zone and the westward continuation of the STDS. The southwest flank of the dome is delineated by the Khanjar shear zone, a SW-dipping down to the southwest normal sense shear zone. A pervasive foliation (S2) exposed across the dome dips ~20-25° NE on the northeast flank of the dome and ~25-30° SW on the southwest flank and includes a down dip stretching lineation (Ls2). Sillimanite, kyanite, staurolite, and garnet grew within the S2 foliation and in places defined the Ls2 lineation indicating that these structures formed at peak-metamorphic conditions (<8 kbar and <800°T, Robyr et al 2006). Quartz and feldspar deformation temperatures across the dome preserve higher temperature textures, 500-700°C, in the core and progressively lower temperature textures, 400-500°C toward the flanks. Contours of deformation temperatures yield a domal geometry, similar to the domed S2 foliation and the temperature conditions provide additional support for the S2 foliation forming at peak metamorphic conditions. Quartz

  9. Patterns of Volcanism Associated With Oligocene to Recent Dome Uplift, West Antarctic Rift System

    NASA Astrophysics Data System (ADS)

    Le Masurier, W. E.

    2005-12-01

    The Marie Byrd Land dome lies on the Pacific coast of the West Antarctic rift system. It is a structural dome defined by elevations of a low-relief erosion surface that is exposed in fault- block nunataks. The dome has roughly 3000 m of structural relief and is about 800 km in diameter.The growth of the dome has been closely associated with two rather unusual patterns of volcanic activity that provide keys to the timing and rate of uplift. (1) The ages of basaltic rocks that rest on the erosion surface become systematically older with increasing elevation of the surface, e.g. 6.27 Ma at 600 m elevation, 27 Ma at 2700 m, etc., suggesting that uplift began around 27 Ma and continued to 6 Ma at roughly 100m/m.y. (2) The oldest of 18 felsic shield volcanoes formed around 19 Ma at the dome crest. The remaining felsic volcanoes become systematically younger toward the distal flanks of the dome, along linear, fault-controlled, N-S and E-W chains. Late Pleistocene (active) volcanoes lie at the north, south, east, and west margins of the dome, suggesting that uplift proceeded systematically from 19 Ma to the present by centrifugal extension of relict fractures during uplift, accompanied by the rise of felsic magmas from crustal reservoirs. Teleseismic studies (Winberry and Anandakrishnan, 2004) show that the crust has been thinned over the dome crest, and that the dome is supported by low density mantle. Tomographic images near the dome (Sieminski, et al., 2003) show a low velocity column extending down to the transition zone. The Antarctic plate has been stationary at least since the Eocene. In the apparent absence of a mechanism driven by plate tectonics, it is reasonable to infer that mantle plume activity has produced these spatial and temporal patterns of volcanism focused around dome uplift, rather than the more familiar linear volcanic chains associated with moving plates.

  10. Physical and Thermal Comfort Properties of Viscose Fabrics made from Vortex and Ring Spun Yarns

    NASA Astrophysics Data System (ADS)

    Thilagavathi, G.; Muthukumar, N.; Kumar, V. Kiran; Sadasivam, Sanjay; Sidharth, P. Mithun; Nikhil Jain, G.

    2016-11-01

    Viscose fiber is frequently preferred for various types of inner and outer knitwear products for its comfort and visual characteristics. In this study, the physical and thermal comfort properties of viscose fabrics made from ring and vortex yarns have been studied to explore the impact of spinning process on fabric properties. 100% viscose fibers were spun into yarns by ring and vortex spinning and the developed yarns were converted to single jersey fabrics. The results indicated that fabrics made from vortex spun yarns had better pilling resistance over that of those from ring spun yarns. There was no significant difference between bursting strength values of vortex and ring spun yarn fabrics. Fabrics made from ring yarn had better dimensional stability compared to fabrics made from vortex yarn. The air permeability and water vapour permeability of vortex yarn fabrics were higher than ring spun yarn fabrics. The vortex yarn fabrics had better thermal comfort properties compared to ring yarn fabrics.

  11. Solidification process in melt spun Nd-Fe-B type magnets

    SciTech Connect

    Li, Changping

    1998-02-23

    A generalized solidification model has been developed based on a systematic investigation on the microstructure of melt spun Nd-Fe-B alloys. Melt spinning was conducted on initial stoichiometric and TiC added Nd2Fe14B (2-14-1) compositions to produce under, optimally and over quenched microstructures. Microstructural characterization was carried out by TEM, SEM, Optical microscopy, XRD, DTA, VSM and DC SQUID techniques. By taking the dendritic breakup during recalescence into consideration, this generalized model has successfully explained the solidification process of the melt spun Nd-Fe-B alloys. Challenging the conventional homogeneous nucleation models, the new model explains the fine and uniform equiaxed 2-14-1 microstructure in optimally quenched ribbons as a result of the breakup of the 2-14-1 dendrites which nucleate heterogeneously from the wheel surface and grow dendritically across the ribbon thickness due to the recalescence. Besides this dendritic breakup feature, the under quenched microstructure is further featured with another growth front starting with the primary solidification of Fe phase near the free side, which results in a coarsely grained microstructure with Fe dendritic inclusions and overall variation in microstructure across the ribbon thickness. In addition, because a epitaxy exists between the Fe phase and the 2-14-1, the so-formed coarse 2-14-1 grains may be textured. C-axis texturing was observed in under quenched ribbons. As a constraint to solidification models in this system, the cause and characteristics of this phenomenon has been studied in detail to test the authors proposed model, and agreement has been found. An extension has also been made to understand the solidification process when TiC is added, which suggests that Ti and C slow down the growth front of both Fe and 2-14-1 phase.

  12. Geology of the Upheaval Dome impact structure, southeast Utah

    USGS Publications Warehouse

    Kriens, B.J.; Shoemaker, E.M.; Herkenhoff, K. E.

    1999-01-01

    Two vastly different phenomena, impact and salt diapirism, have been proposed for the origin of Upheaval Dome, a spectacular scenic feature in southeast Utah. Detailed geologic mapping and seismic refraction data indicate that the dome originated by collapse of a transient cavity formed by impact. Evidence is as follows: (1) sedimentary strata in the center of the structure are pervasively imbricated by top-toward-the-center thrust faulting and are complexly folded as well; (2) top-toward-the-center normal faults are found at the perimeter of the structure; (3) clastic dikes are widespread; (4) the top of the underlying salt horizon is at least 500 m below the surface at the center of the dome, and there are no exposures of salt or associated rocks of the Paradox Formation in the dome to support the possibility that a salt diapir has ascended through it; and (5) planar microstructures in quartz grains, fantailed fracture surfaces (shatter surfaces), and rare shatter cones are present near the center of the structure. We show that the dome formed mainly by centerward motion of rock units along listric faults. Outcrop-scale folding and upturning of beds, especially common in the center, are largely a consequence of this motion. We have also detected some centerward motion of fault-bounded wedges resulting from displacements on subhorizontal faults that conjoin and die out within horizontal bedding near the perimeter of the structure. The observed deformation corresponds to the central uplift and the encircling ring structural depression seen in complex impact craters. Copyright 1999 by the American Geophysical Union.

  13. Imaging the structural changes and instability of the Merapi dome

    NASA Astrophysics Data System (ADS)

    Darmawan, Herlan; Walter, Thomas; Nikkhoo, Mehdi; Richter, Nicole; Troll, Valentin

    2016-04-01

    Actively growing volcano domes may gradually oversteepen, which can lead to catastrophic collapse and associated block and ash flows. Here we test how the structural architecture of such instability is initiated and gradual altered by volcanic activity. After the climactic 2010 eruption, the dome at Merapi volcano has been regrown and partially destroyed again during several eruptions that occurred between 2012 and 2014. At least 6 eruptions produced 1 to 2 km high ash columns and three major fractures formed that split the dome into several segments. Here we elaborate the geometric details of these structural continuing changes. We combine three methodologies (LiDAR-, image-, and thermal-analysis) in order to investigate the dynamic structures on the Merapi dome with a so far unprecedented level of detail. Fixed cameras first identified an unstable block that appeared after the Nov 18, 2013 eruption. We then identified a gradual augmentation of the fracture dimensions, associated with eruptions on March 10, March 24 and April 10, 2014. LiDAR surveys executed before and after these eruptions show structural details of this instability, which we compare with high resolution thermal imagery. We observe that the fractures form at pre-defined anisotropies, and that they concentrate the thermal signal. These thermal concentrations may point to zones of ongoing hydro-thermal mineralization and alteration processes. We therefore hypothesize that two mechanisms of destabilization are presently at play, one associated with small sized eruptions developing structural instability, and the other with continued hydro-thermal alteration and potential weakening along these newly developed structures. Close observation is therefore required at Merapi volcano, as the formation of block and ash flows is structurally initiated long before parts of the dome finally collapse.

  14. Dome cities for extreme environments

    NASA Technical Reports Server (NTRS)

    Leonard, Raymond S.; Schwartz, Milton

    1992-01-01

    Extreme environments whether they be the frigid nights of the polar regions, the burning sands of the desert, or the harsh environment of space pose interesting challenges to the architect, the engineer, and the constructor in their efforts to create habitats for mankind. In space, the goals are to provide radiation protection while also providing an aesthetic living environment for long duration missions. Because of the need to provide both radiation protection and options for expansion of base facilities, a unique structural system which separates the radiation protection systems from the pressure envelope of the habitats was created. The system uses cable networks in a tensioned structural system, which supports the lunar regolith used for shielding above the facilities. The system is modular, easily expandable, and simple to construct. Additional innovations include the use of rock melting perpetrators for piles and anchoring deadmen, and various sized craters to provide side shielding. The reflective properties of the fabric used in the membrane are utilized to provide diffuse illumination. The use of craters along with the suspended shielding allows the dome to be utilized in fashions similar to those proposed by various designers unaware of the Moon's hostile radiation environment. Additional topics addressed deal with construction techniques for large domes, i.e., on the order of 100's to 1000's of meters, thermal control, the integration of tertiary water treatment schemes with architectural design, human factors, and its implications for the design of habitats for long term use in extreme environments.

  15. Thermal properties of continuously spun carbon nanotube fibres

    NASA Astrophysics Data System (ADS)

    Koziol, Krzysztof K.; Janas, Dawid; Brown, Elisabetta; Hao, Ling

    2017-04-01

    As indicated by theory and experimental measurements individual carbon nanotubes (CNTs) have very high values of thermal conductivity. One of the challenges is to achieve high thermal conductivity in macroscopic assemblies of CNTs such as fibres, films and composites, paving the way to a wide range of applications. CNT fibres have tremendous potential in succeeding as the future materials for a variety of applications when properties at the nanoscale are translated to their macroscopic assemblies. In this paper we report the measurements of thermal conductivity of continuously spun CNT fibres and its dependence on temperature. Thermal conductivity measurements were performed using in-house built temperature sensing microscope probe. Specific thermal conductivity of CNT fibres showed an order of magnitude advantage over the traditional materials used for heat dissipation.

  16. A history of semi-active laser dome and window materials

    NASA Astrophysics Data System (ADS)

    Sullivan, Roger M.

    2014-05-01

    Semi-Active Laser (SAL) guidance systems were developed starting in the mid-1960's and today form an important class of precision guided weapons. The laser wavelengths generally fall in the short wave infrared region of the spectrum. Relative to passive, image based, infrared seekers the optical demands placed on the domes or windows of SAL seekers is very modest, allowing the use of low cost, easily manufactured materials, such as polycarbonate. This paper will examine the transition of SAL window and dome science and technology from the laboratory to battlefield, with special emphasis on the story of polycarbonate domes.

  17. Environmental assessment: Richton Dome site, Mississippi

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Richton Dome site in Mississippi as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Richton Dome site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EAs. The site is in the Gulf interior region, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains two other potentially acceptable sites--the Cypress Creek Dome site in Mississippi and the Vacherie Dome site in Louisiana. Although the Cypress Creek Dome and the Vacherie Dome sites are suitable for site characterization, the DOE has concluded that the Richton Dome site is the preferred site in the Gulf interior region. On the basis of the evaluations reported in this EA, the DOE has found that the Richton Dome site is not disqualified under the guidelines.

  18. Turning Norton's Dome Against Material Induction

    NASA Astrophysics Data System (ADS)

    Dawid, Richard

    2015-09-01

    John Norton has proposed a position of "material induction" that denies the existence of a universal inductive inference schema behind scientific reasoning. In this vein, Norton has recently presented a "dome scenario" based on Newtonian physics that, in his understanding, is at variance with Bayesianism. The present note points out that a closer analysis of the dome scenario reveals incompatibilities with material inductivism itself.

  19. Environmental assessment: Richton Dome Site, Mississippi

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Richton Dome site in Mississippi as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Richton Dome site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOE prepared the final EAs. The site is in the Gulf interior region, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains two other potentially acceptable sites--the Cypress Creek Dome site in Mississippi and the Vacherie Dome site in Louisiana. Although the Cypress Creek Dome and the Vacherie Dome sites are suitable for site characterization, the DOE has concluded that the Richton Dome site is the preferred site in the Gulf interior region. On the basis of the evaluations reported in this EA, the DOE has found that the Richton Dome site is not disqualified under the guidelines.

  20. Volcanic ash at Santiaguito dome complex, Guatemala

    NASA Astrophysics Data System (ADS)

    Hornby, Adrian; Kendrick, Jackie; Lavallée, Yan; Cimarelli, Corrado; von Aulock, Felix; Rhodes, Emma; Kennedy, Ben; Wadsworth, Fabian

    2015-04-01

    Dome-building volcanoes often suffer episodic explosions. Examination of eruptive activity at Santiaguito dome complex (Guatemala) reveals that gas-and-ash explosions are concordant with rapid inflation/ deflation cycles of the active dome. During these explosions strain is accommodated along marginal faults, where tensional fracture mechanisms and friction dominate, complicating the model of ash generation by bubble rupture in magma. Here, we describe textural features, morphology and petrology of ash collected before, during and after a dome collapse event at Santiaguito dome complex on the 28th November 2012. We use QEM-scan (on more than 35000 grains), laser diffraction granulometry and optical and scanning microscopy to characterise the samples. The ash samples show a bimodal size distribution and a range of textures, crystal content and morphologies. The ash particles are angular to sub-angular and are relatively dense, so do not appear to comprise of pore walls. Instead the ash is generally blocky (>70%), similar to the products of shear magma failure. The ash samples show minor variation before, during and after dome collapse, specifically having a smaller grain size and a higher fraction of phenocrysts fragments before collapse. Textural analysis shows vestiges of chemically heterogeneous glass (melt) filaments originating from the crystals and crosscut by fragmentation during volcanic ash formation. High-velocity friction can induce melting of dome lavas, producing similar disequilibrium melting textures. This work shows the importance of deformation mechanisms in ash generation at lava domes and during Vulcanian activity.

  1. Submarine Analogs to Venusian Pancake Domes

    NASA Technical Reports Server (NTRS)

    Bridges, Nathan T.

    1995-01-01

    The morphology and dimensions of the large diameter, steep-sided, flat-topped "pancake domes" on Venus make them unlike any type of terrestrial subaerial volcano. Comparisons between images of Hawaiian seamounts and pancake domes show similarities in shapes and secondary features. The morphometry of pancake domes is closer to that of Pacific seamounts than subaerial lava domes. Considering both morphology and morphometry, seamounts seem a better analog to the pancake domes. The control of volatile exsolution by pressure on Venus and the seafloor can cause lavas to have similar viscosities and densities, although the latter will be counteracted by high buoyancy underwater. However, analogous effects of the Venusian and seafloor alone are probably not sufficient to produce similar volcanoes. Rather, Venusian lavas of various compositions may behave like basalt on the seafloor if appropriate rates and modes of extrusion and planetary thermal structure are also considered.

  2. Key variables influencing patterns of lava dome growth and collapse

    NASA Astrophysics Data System (ADS)

    Husain, T.; Elsworth, D.; Voight, B.; Mattioli, G. S.; Jansma, P. E.

    2013-12-01

    Lava domes are conical structures that grow by the infusion of viscous silicic or intermediate composition magma from a central volcanic conduit. Dome growth can be characterized by repeated cycles of growth punctuated by collapse, as the structure becomes oversized for its composite strength. Within these cycles, deformation ranges from slow long term deformation to sudden deep-seated collapses. Collapses may range from small raveling failures to voluminous and fast-moving pyroclastic flows with rapid and long-downslope-reach from the edifice. Infusion rate and magma rheology together with crystallization temperature and volatile content govern the spatial distribution of strength in the structure. Solidification, driven by degassing-induced crystallization of magma leads to the formation of a continuously evolving frictional talus as a hard outer shell. This shell encapsulates the cohesion-dominated soft ductile core. Here we explore the mechanics of lava dome growth and failure using a two-dimensional particle-dynamics model. This meshless model follows the natural evolution of a brittle carapace formed by loss of volatiles and rheological stiffening and avoids difficulties of hour-glassing and mesh-entangelment typical in meshed models. We test the fidelity of the model against existing experimental and observational models of lava dome growth. The particle-dynamics model follows the natural development of dome growth and collapse which is infeasible using simple analytical models. The model provides insight into the triggers that lead to the transition in collapse mechasnism from shallow flank collapse to deep seated sector collapse. Increase in material stiffness due to decrease in infusion rate results in the transition of growth pattern from endogenous to exogenous. The material stiffness and strength are strongly controlled by the magma infusion rate. Increase in infusion rate decreases the time available for degassing induced crystallization leading to a

  3. The Montagne Noire migmatitic dome emplacement (French Massif Central): new insights from petrofabric and AMS studies

    NASA Astrophysics Data System (ADS)

    Charles, Nicolas; Faure, Michel; Chen, Yan

    2009-11-01

    In the southern French Massif Central, the Montagne Noire axial zone is a NE-SW elongated granite-migmatite dome emplaced within Visean south-verging recumbent folds and intruded by syn- to late-migmatization granitoids. The tectonic setting of this dome is still disputed, thus several models have been proposed. In order to better understand the emplacement mechanism of this dome, petrofabric and Anisotropy of Magnetic Susceptibility (AMS) studies have been carried out. In the granites and migmatites that form the dome core, magmatic texture and to a lesser extent weak solid-state texture are dominant. As a paramagnetic mineral, biotite is the main carrier of the magnetic susceptibility. On the basis of 135 AMS sites, the magnetic fabrics appear as independent of the lithology but related to the dome architecture. Coupling our results with previous structural and geochronological studies, allows us to propose a new emplacement model. Between 340-325 Ma, the Palaeozoic series underwent a compressional deformation represented by nappes and recumbent folds involving the thermal event leading to partial melting. Until ˜325-310 Ma, the dome emplacement was assisted by diapiric processes. An extensional event took place at ˜300 Ma, after the emplacement of the late to post-migmatitic granitic plutons. In the northeast side of the dome, a brittle normal-dextral faulting controlled the opening of the Graissessac coal basin.

  4. Central Pit and Dome Formation as Seen in Occator Crater, Ceres

    NASA Astrophysics Data System (ADS)

    Schenk, Paul M.; Buczkowski, Debra; Scully, Jennifer E. C.; De Sanctis, Maria Cristina; Schmidt, Britney E.; O'Brien, David P.; Hiesinger, Harald; Sizemore, Hanna G.; Ammannito, Eleonora; Raymond, Carol; Russell, Christopher T.; Dawn Science Team

    2016-10-01

    Dawn mapping of Ceres revealed that central depressions (or pits) are common in craters >75 km. The best preserved of these is Occator (D~92 km), where the pit is associated with a major bright deposit dominated by carbonates. The pit is ~9 km wide, 600-800 m deep and flanked by asymmetric massifs 0.7 to 1.3 km high. The pit is partially filled by a fractured central dome ~3 km wide and 700 m high. Fracturing could have been due to dome inflation by "magma" or by subsurface freezing of ice. Within the bright material, two color units are mapped, including a paler surface unit and a more yellowish to reddish unit exposed within the most fractured parts of the dome surface and at small bright spots, at least some of which could be post-Occator small craters. Some bright materials form as discrete small spots midslope along the pit wall and others avoid small hills, suggesting partial topographic control. Stratigraphic relations are ambiguous but suggest formation of a smooth carapace some meters thick that was subsequently disrupted by fractures crossing the floor of Occator, and by uplift of the dome surface. Pit and dome morphologies, including dome fracturing are potentially analogous to central pits and domes in many craters on Ganymede and Callisto, suggesting some commonality in formation processes. The absence of center pits or domes on Saturnian satellites could be related to much lower temperatures on those bodies. The prominence of central pits and domes on Ceres confirms the importance of volatile materials, mostly likely water ice, in the outer layers of Ceres, especially as compared to Vesta.

  5. Phenocryst fragments in rhyolitic lavas and lava domes

    NASA Astrophysics Data System (ADS)

    Allen, S. R.; McPhie, J.

    2003-08-01

    Although rhyolitic lavas and lava domes are characterised by evenly porphyritic textures, not all the phenocrysts are whole euhedra. We undertook image analysis of 46 rhyolitic lava and lava dome samples to determine the abundance and shape of quartz and feldspar phenocryst fragments. Phenocryst fragments were identified in nearly all samples. On average, fragments amount to ˜5% of the total phenocryst population, or ˜0.5 modal%. The abundance of fragments in lavas and lava domes is not related to the groundmass texture (whether vesicular, flow banded, massive, glassy or crystalline), nor to distance from source. Fragments are, however, more abundant in samples with higher phenocryst contents. The phenocryst fragments in rhyolitic lavas and lava domes are mainly medium to large (0.5-3.5 mm), almost euhedral crystals with only a small portion removed, or chunky, equant, subhedral fragments, and occur in near-jigsaw-fit or clast-rotated pairs or groups. The fragments probably formed in response to decompression of large melt inclusions. Shear during laminar flow then dismembered the phenocrysts; continued laminar shear separated and rotated the fragments. Fractures probably formed preferentially along weaknesses in the phenocrysts, such as zones of melt inclusions, cleavage planes and twin composition planes. Rare splintery fragments are also present, especially within devitrified domains. Splinters are attributed to comminution of solid lava adjacent to fractures that were later healed. For comparison, we measured crystal abundance in a further 12 rhyolite samples that include block and ash flow deposits and ignimbrite. Phenocryst fragments within clasts in the block and ash flow samples showed similar shapes and abundances to those fragments within the lava and lava domes. Crystal fragments are much more abundant in ignimbrite (exceeding 67% of the crystal population) however, and dominated by small, equant, anhedral chunks or splinters. The larger crystals in

  6. Magnetic properties of (Sm,Y)5Fe17 melt-spun ribbons

    NASA Astrophysics Data System (ADS)

    Saito, Tetsuji; Nishio-Hamane, Daisuke

    2011-04-01

    An investigation of the synthesis of the (Sm1-xYx)5Fe17 (x = 0 to 0.5) phase and its magnetic properties is presented. (Sm1-xYx)5Fe17 (x = 0 to 0.5) melt-spun ribbons that fully or mainly consisted of the amorphous phase and which showed low coercivity were prepared. Heat treatment of the melt-spun ribbons resulted in the formation of the (Sm,Y)5Fe17 phase. The highest remanence, 50 emu/g, was achieved in the annealed (Sm0.7Y0.3)5Fe17 melt-spun ribbon. However,the annealed (Sm1-xYx)5Fe17 (x = 0.4 to 0.5) melt-spun ribbons did not contain the (Sm,Y)5Fe17 phase and showed low coercivity values.

  7. Geothermal patterns of Louisiana salt domes

    SciTech Connect

    Kumar, M.B. )

    1989-09-01

    Seven salt domes of Louisiana, in the shallow to intermediate depth ranges, were selected for the investigation of geothermal patterns associated with them. Equilibrium geotemperatures were determined from the bottom hole temperatures of wells drilled in the salt dome areas. Isothermal contour mapping was attempted for various depth levels, namely, 8,000, 9,000, 10,000, 12,000, and 14,000 ft. Limited availability of data permitted construction of isothermal contour maps on some of the depth horizons for each of the domes.

  8. Autonomous Dome for a Robotic Telescope

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Sengupta, A.; Ganesh, S.

    2016-12-01

    The Physical Research Laboratory operates a 50 cm robotic observatory at Mount Abu (Rajsthan, India). This Automated Telescope for Variability Studies (ATVS) makes use of the Remote Telescope System 2 (RTS2) for autonomous operations. The observatory uses a 3.5 m dome from Sirius Observatories. We have developed electronics using Arduino electronic circuit boards with home grown logic and software to control the dome operations. We are in the process of completing the drivers to link our Arduino based dome controller with RTS2. This document is a short description of the various phases of the development and their integration to achieve the required objective.

  9. Structures and magnetic properties of Sm5Fe17 melt-spun ribbon

    NASA Astrophysics Data System (ADS)

    Saito, Tetsuji; Miyoshi, Hiroya; Nishio-Hamane, Daisuke

    2012-04-01

    The crystallization behavior of amorphous Sm5Fe17 melt-spun ribbon was studied. The crystallized phases in annealed specimens were deeply dependent on both the annealing temperature and the heating rate. The optimally annealed Sm5Fe17 melt-spun ribbon consisted of Sm5Fe17 grains of around 50-100 nm in diameter and exhibited a remanence of 50 emu/g with a high coercivity of 40 kOe.

  10. Pressure Dome for High-Pressure Electrolyzer

    NASA Technical Reports Server (NTRS)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  11. Hyperthyroidism with dome-and-dart T wave: A case report

    PubMed Central

    Lai, Ping; Yuan, Jing-ling; Xue, Jin-hua; Qiu, Yue-qun

    2017-01-01

    Abstract Rationale: Dome-and-dart T waves (or bifid T waves) are a rare phenomenon in the surface electrocardiogram. These wave forms are mainly observed in patients with congenital heart disease such as atrial septal defect and ventricular septal defect. And hyperthyroidism who presented with an electrocardiogram that had dome-and-dart T waves in a precordial lead is never been reported. Patient concerns: The patient presented with continuous tachycardia, palpitations, chest tightness, and headache for 4 days, and aggravated for 1 day. Diagnoses: Hyperthyroidism. Interventions: Methimazole. Outcomes: All symptoms were alleviated. Lessons: Dome-and-dart or bifid T waves have been reported in the conventional 12-lead electrocardiograms in some patients with congenital heart disease. The case illustrated here, to the best of our knowledge, dome-and-dart or bifid T waves may associate with hyperthyroidism patients. PMID:28178156

  12. Regenerated cellulose fibers spun-dyed with carbon black/latex composite dispersion.

    PubMed

    Wang, Chunxia; Du, Changsen; Tian, Anli; Fu, Shaohai; Xu, Changhai

    2014-01-30

    A carbon black (CB)/latex composite was prepared by the method of miniemulsion polymerization for use as a colorant for spun dyeing of regenerated cellulose fibers. Analysis of experimental results revealed that the CB/latex composite had a small particle size and a narrow particle size distribution which were important to ensure a stable dispersion being later added to spinning solution. A good stability of the prepared CB/latex composite dispersion in the spinning solution indicated that it was highly possible to use the CB/latex composite as a colorant for spun dyeing of regenerated cellulose fibers. When a 3.5% mass ratio of CB/latex composite to cellulose was used for spun dyeing, the spun-dyed fibers had the highest tensile strength, breaking elongation and color strength. The rubbing and washing color fastnesses of spun-dyed regenerated cellulose fibers could satisfy requirements of most textiles. This study provided a new insight into producing spun-dyed regenerated cellulose with a novel colorant.

  13. Environmental assessment overview: Richton Dome site, Mississippi

    SciTech Connect

    none,

    1986-05-01

    In February 1983, the US Department of Energy (DOE) identified the Richton Dome site in Mississippi as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Richton Dome site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. The site is in the Gulf interior region, which is one of five distinct geohydrologic settings considered for the first repository. On the basis of the evaluations reported in this EA, the DOE has found that the Richton Dome site is not disqualified under the guidelines. On the basis of these findings, the DOE is nominating the Richton Dome site as one of five sites suitable for characterization. 3 figs.

  14. Experimental Studies of Lava Dome Fracture

    NASA Astrophysics Data System (ADS)

    Smith, R.; Sammonds, P. R.; Kilburn, C. R.

    2005-12-01

    Renewed extrusion at andesitic to dacitic lava domes and collapses of these domes are usually preceded by fracturing and frictional sliding of material in and around the lava dome and magma conduit. This is observed through the occurrence of shallow high frequency earthquakes. Samples of andesite from Mount Shasta in the Cascades, a typical material for both lava domes and shallow underlying country rock, have been deformed in compression and tension, at temperatures of up to 900°C, and under confining pressures of up to 70MPa. During these tests the axial load, sample deformation and acoustic emissions were recorded, in order to compare the results with field observations of deformation and short period seismicity at lava domes. Typical strengths at room temperature and pressure were 6MPa in tension, and 100MPa in compression. Increased temperatures increased the tensile strength, but reduced the compressive strength, whereas both strengths increased with increasing confining pressure. There were ~10 times more acoustic emissions at room temperature than at maximum test temperatures, indicating that increased temperatures favour ductile, rather than brittle, failure. These results suggest that young, hot lava domes may collapse or erupt with little precursory short period seismicity, whilst older, cooler domes are likely to exhibit stronger short period seismic precursors. However, hotter material is likely to exhibit more recognisable deformation precursors. This is consistent with the seismicity observed after the 18 May 1980 climactic eruption at Mount St Helens, where there was ~100 times more seismicity prior to eruptions in 1985 and 1986 than there was prior to eruptions in 1980 and 1981. During these later eruptions, the interior of the dome would still have been ductile due to its temperature and the overburden weight acting as a confining pressure, but the large amount of pre-failure deformation in this zone could drive fracturing of the cooler outer

  15. Topical reports on Louisiana salt domes

    SciTech Connect

    Not Available

    1983-09-01

    The Institute for Environmental Studies at Louisiana State University conducted research into the potential use of Louisiana salt domes for disposal of nuclear waste material. Topical reports generated in 1981 and 1982 related to Vacherie and Rayburn's domes are compiled and presented, which address palynological studies, tiltmeter monitoring, precise releveling, saline springs, and surface hydrology. The latter two are basically a compilation of references related to these topics. Individual reports are abstracted.

  16. The design research of a spinel dome

    NASA Astrophysics Data System (ADS)

    Zhao, Hongwei; Hou, Tianjin; Zhu, Bin; Huang, Qiu; Gao, Zhifeng

    2011-08-01

    Based on the aerodynamic heating simulated results of a spinel middle-infrared (Mid IR) image guide missile dome flying at supersonic speed, a series of experiments are made and some methods of eliminating aero-heating effect are carried out successfully. First, a simulation experiment on the ground discarding an outside protective shell of a spinel dome is accomplished in order to inspect the withstanding impact ability of the dome. Second, an arc wind tunnel experiment is fulfilled to obtain thermal mechanics characteristic of the spinel dome, and a method to buildup obviously mechanics intensity is approved which is coating diamond protective layer on the external wall of the spinel dome. Third, two heated dome imaging experiments on the ground are made to study the aero-optical phenomenon. Finally, a rocket sled experiment of a guide missile head is made successfully. Experimental results show that when the guide missile head flies in a supersonic, by adjusting the frame integration time of detector etc. the aero-optic effect would decrease greatly.

  17. Extrusion cycles during dome-building eruptions

    NASA Astrophysics Data System (ADS)

    de' Michieli Vitturi, M.; Clarke, A. B.; Neri, A.; Voight, B.

    2013-06-01

    We identify and quantify controls on the timescales and magnitudes of cyclic (periodic) volcanic eruptions using the numerical model DOMEFLOW (de' Michieli Vitturi et al., 2010) which was developed by the authors for magma systems of intermediate composition. DOMEFLOW treats the magma mixture as a liquid continuum with dispersed gas bubbles and crystals in thermodynamic equilibrium with the melt and assumes a modified Poiseuille form of the viscous term for fully developed laminar flow in a conduit of cylindrical cross-section. During ascent, magma pressure decreases and water vapor exsolves and partially degasses from the melt as the melt simultaneously crystallizes, causing changes in mixture density and viscosity. Two mechanisms previously proposed to cause periodic eruption behavior have been implemented in the model and their corresponding timescales explored. The first applies a stick-slip model in which motion of a shallow solid plug is resisted by static/dynamic friction, as described in Iverson et al. (2006). For a constant magma supply rate at depth, this mechanism yields cyclic extrusion with timescales of seconds to tens of seconds with values generally depending on assumed friction coefficients. The second mechanism does not consider friction but treats the plug as a high-viscosity Newtonian fluid. During viscous resistance, pressure beneath the degassed plug can increase sufficiently to overcome dome overburden, plug weight, and viscous forces, and ultimately drive the plug from the conduit. In this second model cycle periods are on the order of hours, and decrease with increasing magma supply rate until a threshold is reached, at which point periodicity disappears and extrusion rate becomes steady (vanishingly short periods). Magma volatile content for fixed chamber pressure has little effect on cycle timescales, but increasing volatile content increases mass flow rate and cycle magnitude as defined by the difference between maximum and minimum

  18. Rhyolite domes in the Krafla area, North Iceland. Densities and deformation fields

    NASA Astrophysics Data System (ADS)

    Agustsdottir, T.; Einarsson, P.; Gudmundsson, M. T.

    2009-12-01

    Krafla is a central volcano in the Northern Volcanic Zone (NVZ) of Iceland. It began forming about 200 000 years BP, has a caldera, and is transected by a N10°A trending fissure swarm. Krafla’s products are mostly basaltic but rhyolite domes have formed around the caldera rims. Krafla’s products were mostly erupted during the last glacial period, 110 000 years BP to 10 000 years BP. Silicic rocks in Iceland are generally associated with central volcanoes and are often emplaced on or around caldera rims. Rhyolite magma can rise, due to buoyancy forces and either form a cryptodome in the shallow crust or rise to the surface, where it erupts. Due to its high viscosity and resistance to flow it often accumulates and forms a lava dome over the vent. A gravity survey was carried out in the area of Krafla in 2007 and 2008 to determine the mean bulk density values of rhyolite domes. Data on density and volumes is essential for meaningful modelling of the emplacement of cryptodomes and lava domes. Such data are scarce. Profiles were measured over three formations, ranging in size from Hlidarfjall (310 m high and 2 km long), formed under ice 90 000 years BP, to Hrafntinnuhryggur (80 m high and 2,5 km long) formed 24 000 years BP under a glacier to Hraunbunga (125 m high and 1,8 km long) formed 10 000 years BP. Mean bulk density for each formation was obtained by the Nettleton method. The results are that all the domes have low densities, reflecting both low grain-density and high porosity. The domes’s density values are significantly smaller than those of the surroundings, creating a density contrast possibly sufficient to drive the ascent of rhyolite magma. Furthermore, results from gravity data demonstrate that these formations are neither buried by younger volcanic eruptives nor are any roots detected. The domes studied were therefore emplaced as vent-forming domes. Additionally, we propose a model to describe the deformation field above a rising batch of magma

  19. Radially fractured domes: A comparison of Venus and the Earth

    NASA Technical Reports Server (NTRS)

    Janes, Daniel M.; Squyres, Steven W.

    1993-01-01

    Radially fractured domes are large, tectonic and topographic features discovered on the surface of Venus by the Magellan spacecraft. They are thought to be due to uplift over mantle diapirism, and to date are known to occur only on Venus. Since Venus and the Earth are grossly similar in size, composition and structure, we seek to understand why these features have not been seen on the Earth. We model the uplift and fracturing over a mantle diapir as functions of lithospheric thickness and diapir size and depth. We find that lithospheres of the same thickness on the Earth and Venus should respond similarly to the same sized diapir, and that radially fractured domes should form most readily in thin oceanic lithospheres on Earth if diapiric activity is similar on the two planets. However, our current knowledge of the Earth's oceanic floors is insufficient to confirm or deny the presence of radially fractured domes. We compute the expected dimensions for these features on the Earth and suggest a search for them to determine whether mantle diapirism operates similarly on the Earth and Venus.

  20. Charged nano-domes and bubbles in epitaxial graphene.

    PubMed

    Trabelsi, A Ben Gouider; Kusmartsev, F V; Robinson, B J; Ouerghi, A; Kusmartseva, O E; Kolosov, O V; Mazzocco, R; Gaifullin, Marat B; Oueslati, M

    2014-04-25

    For the first time, new epitaxial graphene nano-structures resembling charged 'bubbles' and 'domes' are reported. A strong influence, arising from the change in morphology, on the graphene layer's electronic, mechanical and optical properties has been shown. The morphological properties of these structures have been studied with atomic force microscopy (AFM), ultrasonic force microscopy (UFM) and Raman spectroscopy. After initial optical microscopy observation of the graphene, a detailed description of the surface morphology, via AFM and nanomechanical UFM measurements, was obtained. Here, graphene nano-structures, domes and bubbles, ranging from a few tens of nanometres (150–200 nm) to a few μm in size have been identified. The AFM topographical and UFM stiffness data implied the freestanding nature of the graphene layer within the domes and bubbles, with heights on the order of 5–12 nm. Raman spectroscopy mappings of G and 2D bands and their ratio confirm not only the graphene composition of these structures but also the existence of step bunching, defect variations and the carrier density distribution. In particular, inside the bubbles and substrate there arises complex charge redistribution; in fact, the graphene bubble–substrate interface forms a charged capacitance. We have determined the strength of the electric field inside the bubble–substrate interface, which may lead to a minigap of the order of 5 meV opening for epitaxial graphene grown on 4H-SiC face-terminated carbon.

  1. Radar scattering properties of steep-sided domes on Venus

    NASA Technical Reports Server (NTRS)

    Ford, Peter G.

    1994-01-01

    More than 100 quasi-circular steep-sided volcanic domes, with diameters ranging from 6 to 60 km, have been observed on the surface of Venus by the Magellan radar mapper. Assuming that they have the shape of a solidified high-viscosity Newtonian fluid, their radar scattering properties can be studied in detail from Magellan images, since a typical radar swath resolves each dome into several tens of thousands of measurements of radar cross section at incidence angles varying fom 15 deg to 55 deg. Through examination of 20 domes in detail, it appears that many of those situated on lava plains scatter radar in a manner that is indistinguishable from that of the surrounding material, suggesting that either (1) they were formed of a relatively high-density high-viscosity material, e.g., andesite, rather than a lower-density one, e.g., rhyolite or dacite; or (2) that their surfaces share a common origin with those of their surroundings, e.g., through in situ weathering or aeolian deposition.

  2. Ice crystal precipitation at Dome C site (East Antarctica)

    NASA Astrophysics Data System (ADS)

    Santachiara, G.; Belosi, F.; Prodi, F.

    2016-01-01

    For the first time, falling ice crystals were collected on glass slides covered with a thin layer of 2% formvar in chloroform at the Dome Concordia site (Dome C), Antarctica. Samplings were performed in the framework of the 27th Italian Antarctica expedition of the Italian National Program for Research in Antarctica in the period 21 February-6 August 2012. Events of clear-sky precipitations and precipitations from clouds were considered and the replicas obtained were examined under Scanning Electron Microscope (SEM). Several shapes of ice crystals were identified, including "diamond dust" (plates, pyramids, hollow and solid columns), and crystal aggregates varying in complexity. Single events often contained both small (10 μm to 50 μm) and large (hundreds of microns) crystals, suggesting that crystals can form simultaneously near the ground (height of a few hundred metres) and at higher layers (height of thousands of metres). Images of sampled crystal replicas showed that single bullets are not produced separately, but by the disintegration of combinations of bullets. Rimed ice crystals were absent in the Dome C samples, i.e. the only mode of crystal growth was water vapour diffusion. On considering the aerosol in the sampled crystals, we reached the conclusion that inertial impaction, interception and Brownian motion were insufficient to explain the scavenged aerosol. We therefore presume that phoretic forces play a role in scavenging during the crystal growth process.

  3. Enhancement of local air pollution by urban CO(2) domes.

    PubMed

    Jacobson, Mark Z

    2010-04-01

    Data suggest that domes of high CO(2) levels form over cities. Despite our knowledge of these domes for over a decade, no study has contemplated their effects on air pollution or health. In fact, all air pollution regulations worldwide assume arbitrarily that such domes have no local health impact, and carbon policy proposals, such as "cap and trade", implicitly assume that CO(2) impacts are the same regardless of where emissions occur. Here, it is found through data-evaluated numerical modeling with telescoping domains from the globe to the U.S., California, and Los Angeles, that local CO(2) emissions in isolation may increase local ozone and particulate matter. Although health impacts of such changes are uncertain, they are of concern, and it is estimated that that local CO(2) emissions may increase premature mortality by 50-100 and 300-1000/yr in California and the U.S., respectively. As such, reducing locally emitted CO(2) may reduce local air pollution mortality even if CO(2) in adjacent regions is not controlled. If correct, this result contradicts the basis for air pollution regulations worldwide, none of which considers controlling local CO(2) based on its local health impacts. It also suggests that a "cap and trade" policy should consider the location of CO(2) emissions, as the underlying assumption of the policy is incorrect.

  4. Distributions of cranial pathologies provide evidence for head-butting in dome-headed dinosaurs (Pachycephalosauridae).

    PubMed

    Peterson, Joseph E; Dischler, Collin; Longrich, Nicholas R

    2013-01-01

    Pachycephalosaurids are small, herbivorous dinosaurs with domed skulls formed by massive thickening of the cranial roof. The function of the dome has been a focus of debate: the dome has variously been interpreted as the product of sexual selection, as an adaptation for species recognition, or as a weapon employed in intraspecific combat, where it was used in butting matches as in extant ungulates. This last hypothesis is supported by the recent identification of cranial pathologies in pachycephalosaurids, which appear to represent infections resulting from trauma. However, the frequency and distribution of pathologies have not been studied in a systematic fashion. Here, we show that pachycephalosaurids are characterized by a remarkably high incidence of cranial injury, where 22% of specimens have lesions on the dome. Frequency of injury shows no significant difference between different genera, but flat-headed morphs (here interpreted as juveniles or females) lack lesions. Mapping of injuries onto a digitial pachycephalosaurid skull shows that although lesions are distributed across the dome, they cluster near the apex, which is consistent with the hypothesis that the dome functioned for intraspecific butting matches.

  5. A comparison between semi-spheroid- and dome-shaped quantum dots coupled to wetting layer

    NASA Astrophysics Data System (ADS)

    Shahzadeh, Mohammadreza; Sabaeian, Mohammad

    2014-06-01

    During the epitaxial growth method, self-assembled semi-spheroid-shaped quantum dots (QDs) are formed on the wetting layer (WL). However for sake of simplicity, researchers sometimes assume semi-spheroid-shaped QDs to be dome-shaped (hemisphere). In this work, a detailed and comprehensive study on the difference between electronic and transition properties of dome- and semi-spheroid-shaped quantum dots is presented. We will explain why the P-to-S intersubband transition behaves the way it does. The calculated results for intersubband P-to-S transition properties of quantum dots show two different trends for dome-shaped and semi-spheroid-shaped quantum dots. The results are interpreted using the probability of finding electron inside the dome/spheroid region, with emphasis on the effects of wetting layer. It is shown that dome-shaped and semi-spheroid-shaped quantum dots feature different electronic and transition properties, arising from the difference in lateral dimensions between dome- and semi-spheroid-shaped QDs. Moreover, an analogy is presented between the bound S-states in the quantum dots and a simple 3D quantum mechanical particle in a box, and effective sizes are calculated. The results of this work will benefit researchers to present more realistic models of coupled QD/WL systems and explain their properties more precisely.

  6. Robust salt-dome detection using the ranking of texture-based attributes

    NASA Astrophysics Data System (ADS)

    Deriche, Mohamed

    2016-09-01

    The accurate interpretation and analysis of seismic data heavily depends on the robustness of the algorithms used. We focus on the robust detection of salt domes from seismic surveys. We discuss a novel feature-ranking classification model for saltdome detection for seismic images using an optimal set of texture attributes. The proposed algorithm overcomes the limitations of existing texture attribute-based techniques, which heavily depend on the relevance of the attributes to the geological nature of salt domes and the number of attributes used for accurate detection. The algorithm combines the attributes from the Gray-Level Co-occurrence Matrix (GLCM), the Gabor filters, and the eigenstructure of the covariance matrix with feature ranking using the information content. The top-ranked attributes are combined to form the optimal feature set, which ensures that the algorithm works well even in the absence of strong reflectors along the salt-dome boundaries. Contrary to existing salt-dome detection techniques, the proposed algorithm is robust and computationally efficient, and works with small-sized feature sets. I used the Netherlands F3 block to evaluate the performance of the proposed algorithm. The experimental results suggest that the proposed workflow based on information theory can detect salt domes with accuracy superior to existing salt-dome detection techniques.

  7. Distributions of Cranial Pathologies Provide Evidence for Head-Butting in Dome-Headed Dinosaurs (Pachycephalosauridae)

    PubMed Central

    Peterson, Joseph E.; Dischler, Collin; Longrich, Nicholas R.

    2013-01-01

    Pachycephalosaurids are small, herbivorous dinosaurs with domed skulls formed by massive thickening of the cranial roof. The function of the dome has been a focus of debate: the dome has variously been interpreted as the product of sexual selection, as an adaptation for species recognition, or as a weapon employed in intraspecific combat, where it was used in butting matches as in extant ungulates. This last hypothesis is supported by the recent identification of cranial pathologies in pachycephalosaurids, which appear to represent infections resulting from trauma. However, the frequency and distribution of pathologies have not been studied in a systematic fashion. Here, we show that pachycephalosaurids are characterized by a remarkably high incidence of cranial injury, where 22% of specimens have lesions on the dome. Frequency of injury shows no significant difference between different genera, but flat-headed morphs (here interpreted as juveniles or females) lack lesions. Mapping of injuries onto a digitial pachycephalosaurid skull shows that although lesions are distributed across the dome, they cluster near the apex, which is consistent with the hypothesis that the dome functioned for intraspecific butting matches. PMID:23874691

  8. A Cascade of Wnt, Eda, and Shh Signaling Is Essential for Touch Dome Merkel Cell Development

    PubMed Central

    Thoresen, Daniel T.; Miao, Lingling; Williams, Jonathan S.; Wang, Chaochen; Atit, Radhika P.; Wong, Sunny Y.

    2016-01-01

    The Sonic hedgehog (Shh) signaling pathway regulates developmental, homeostatic, and repair processes throughout the body. In the skin, touch domes develop in tandem with primary hair follicles and contain sensory Merkel cells. The developmental signaling requirements for touch dome specification are largely unknown. We found dermal Wnt signaling and subsequent epidermal Eda/Edar signaling promoted Merkel cell morphogenesis by inducing Shh expression in early follicles. Lineage-specific gene deletions revealed intraepithelial Shh signaling was necessary for Merkel cell specification. Additionally, a Shh signaling agonist was sufficient to rescue Merkel cell differentiation in Edar-deficient skin. Moreover, Merkel cells formed in Fgf20 mutant skin where primary hair formation was defective but Shh production was preserved. Although developmentally associated with hair follicles, fate mapping demonstrated Merkel cells primarily originated outside the hair follicle lineage. These findings suggest that touch dome development requires Wnt-dependent mesenchymal signals to establish reciprocal signaling within the developing ectoderm, including Eda signaling to primary hair placodes and ultimately Shh signaling from primary follicles to extrafollicular Merkel cell progenitors. Shh signaling often demonstrates pleiotropic effects within a structure over time. In postnatal skin, Shh is known to regulate the self-renewal, but not the differentiation, of touch dome stem cells. Our findings relate the varied effects of Shh in the touch dome to the ligand source, with locally produced Shh acting as a morphogen essential for lineage specification during development and neural Shh regulating postnatal touch dome stem cell maintenance. PMID:27414798

  9. Features of Bayou Choctaw SPR caverns and internal structure of the salt dome.

    SciTech Connect

    Munson, Darrell E.

    2007-07-01

    The intent of this study is to examine the internal structure of the Bayou Choctaw salt dome utilizing the information obtained from graphical representations of sonar survey data of the internal cavern surfaces. Many of the Bayou Choctaw caverns have been abandoned. Some existing caverns were purchased by the Strategic Petroleum Reserve (SPR) program and have rather convoluted histories and complex cavern geometries. In fact, these caverns are typically poorly documented and are not particularly constructive to this study. Only two Bayou Choctaw caverns, 101 and 102, which were constructed using well-controlled solutioning methods, are well documented. One of these was constructed by the SPR for their use while the other was constructed and traded for another existing cavern. Consequently, compared to the SPR caverns of the West Hackberry and Big Hill domes, it is more difficult to obtain a general impression of the stratigraphy of the dome. Indeed, caverns of Bayou Choctaw show features significantly different than those encountered in the other two SPR facilities. In the number of abandoned caverns, and some of those existing caverns purchased by the SPR, extremely irregular solutioning has occurred. The two SPR constructed caverns suggest that some sections of the caverns may have undergone very regular solutioning to form uniform cylindrical shapes. Although it is not usually productive to speculate, some suggestions that point to the behavior of the Bayou Choctaw dome are examined. Also the primary differences in the Bayou Choctaw dome and the other SPR domes are noted.

  10. Dome, Sweet Dome--Geodesic Structures Teach Math, Science, and Technology Principles

    ERIC Educational Resources Information Center

    Shackelford, Ray; Fitzgerald, Michael

    2007-01-01

    Today, geodesic domes are found on playgrounds, homes, over radar installations, storage facilities, at Disney's Epcot Center, and at World's Fairs. The inventor of the design, Buckminster Fuller, thought that geodesic domes could be used to cover large areas and even designed one to cover all of New York's Manhattan Island. This article details…

  11. On the Measurement of the Electrical Power Produced by Melt Spun Piezoelectric Textile Fibres

    NASA Astrophysics Data System (ADS)

    Matsouka, Dimitroula; Vassiliadis, Savvas; Prekas, Kleanthis; Bayramol, Derman Vatansever; Soin, Navneet; Siores, Elias

    2016-10-01

    Piezoelectric, melt spun, textile fibres as multifunctional materials appeared recently, and they are under thorough investigation and testing in order to define their performance and behaviour. Although piezoelectricity was first reported in 1880 and the piezoelectric behaviour of organic polymers materials has been known since 1969, the fibrous form of the piezoelectric materials under consideration opens new technological horizons; however, it introduces novel restrictions and further complex parameters are involved in their study. The major issue of the current research work is the study of the actual capacity of the piezoelectric fibres, i.e. the electric power produced following mechanical stimulation of the individual fibre. The measurements were made possible after the development of the necessary specific equipment. The test results enabled the ranking of the various types of the piezoelectric fibres according to the respective power generation. The main difference in this research approach is the measurement of the power generated by the fibres. Measurement of the power generated by an electrical power source (in the case of energy harvesting applications which is the prime interest of this research project) is an important characteristic as the requirements of various applications are expressed in units of power. Stating the voltage produced during mechanical deformation of the fibres is not enough (cf. voltage produced due to electrostatic phenomena on textiles where the voltage is in the range is the several kV, but the power is not enough to power a light-emitting diode).

  12. Holodeck: Telepresence Dome Visualization System Simulations

    NASA Technical Reports Server (NTRS)

    Hite, Nicolas

    2012-01-01

    This paper explores the simulation and consideration of different image-projection strategies for the Holodeck, a dome that will be used for highly immersive telepresence operations in future endeavors of the National Aeronautics and Space Administration (NASA). Its visualization system will include a full 360 degree projection onto the dome's interior walls in order to display video streams from both simulations and recorded video. Because humans innately trust their vision to precisely report their surroundings, the Holodeck's visualization system is crucial to its realism. This system will be rigged with an integrated hardware and software infrastructure-namely, a system of projectors that will relay with a Graphics Processing Unit (GPU) and computer to both project images onto the dome and correct warping in those projections in real-time. Using both Computer-Aided Design (CAD) and ray-tracing software, virtual models of various dome/projector geometries were created and simulated via tracking and analysis of virtual light sources, leading to the selection of two possible configurations for installation. Research into image warping and the generation of dome-ready video content was also conducted, including generation of fisheye images, distortion correction, and the generation of a reliable content-generation pipeline.

  13. Low-temperature thermochronology of the central and northwestern Pamir gneiss domes

    NASA Astrophysics Data System (ADS)

    Khan, Jahanzeb; Rutte, Daniel; Ratschbacher, Lothar; Stübner, Konstanze

    2013-04-01

    The Pamir—the western prolongation of the Tibet-Himalaya orogen—resulted from N-S convergence between India and Asia. In the Pamir, the Cenozoic orogeny formed a high-relief mountain knot of ~500 km N-S extent, which contrasts with the ~1000 km wide, low-relief Tibet Plateau. About ~30% of the surface exposure of the Pamir comprises high-grade, middle to lower crustal metamorphic rocks exhumed in Cenozoic syn-orogenic domes; understanding the evolution of these domes is central to understanding the behavior of the Himalaya-Tibet-Pamir orogen because the domes expose a range of shallow to deep structural levels. In the Central Pamir, the (from east to west) Shatput, Muskol, Sarez, and Yazgulem domes form a nearly continuous anticlinorium of greenschist- to mostly amphibolite-facies crystalline rocks, framed by mostly unmetamorphic volcano-sedimentary rocks. The crystalline rocks contain Mesozoic intrusives. The Cenozoic evolution shows a pre-~20 Ma prograde evolution and a post-~20 Ma retrograde evolution accompanied by N-S extension that is replaced since ~10 Ma by renewed N-S shortening. Cenozoic magmatic activity spans 40-15 Ma. Here, we focus on a characterization of the post~20 Ma exhumation history in the central Pamir domes, employing zircon and apatite fission-track and (U-Th)/He thermochronology. These domes yielded apatite fission-track ages between 15 and 6 Ma; there are several trends: (1) Younger ages occur in the west; this is interpreted as an effect of erosional exhumation along the deeply incised western Pamir. (2) Ages young toward the bounding normal shear zones. (3) Age versus elevation relationships indicate most rapid exhumation at ~10 Ma. In the Southern Pamir, low-temperature thermochronology records a longer extensional exhumation history, ending at ~5 Ma in the Alichur dome and ~2 Ma in the Shakhdara dome. In the Northern Pamir, the Triassic Kurgovat gneiss dome shows Cenozoic exhumation from less than 10 km depth; Cenozoic exhumation

  14. Effective pine bark composting with the Dome Aeration Technology

    SciTech Connect

    Trois, Cristina . E-mail: troisc@ukzn.ac.za; Polster, Andreas

    2007-07-01

    In South Africa garden refuse is primarily disposed of in domestic landfills. Due to the large quantities generated, any form of treatment would be beneficial for volume reduction, waste stabilization and resource recovery. Dome Aeration Technology (DAT) is an advanced process for aerobic biological degradation of garden refuse and general waste [Paar, S., Brummack, J., Gemende, B., 1999a. Advantages of dome aeration in mechanical-biological waste treatment. In: Proceedings of the 7th International Waste Management and Landfill Symposium, Cagliari, 4-8 October 1999; Paar, S., Brummack, J., Gemende, B., 1999b. Mechanical-biological waste stabilization by the dome aeration method. Environment Protection Engineering 25 (3/99). Mollekopf, N., Brummack, J., Paar, S., Vorster, K., 2002. Use of the Dome Aeration Technology for biochemical stabilization of waste prior to landfilling. In: Proceedings of the Wastecon 2002, Waste Congress and Exhibition, Durban, South Africa.]. It is a non-reactor open windrow composting process, with the main advantage being that the input material needs no periodic turning. A rotting time of only 3-4 months indicates the high efficiency. Additionally, the low capital/operational costs, low energy inputs and limited plant requirements provide potential for use in aerobic refuse stabilization. The innovation in the DAT process is the passive aeration achieved by thermally driven advection through open windrows caused by temperature differences between the degrading material and the outside environment. This paper investigates the application of Dome Aeration Technology to pine bark composting as part of an integrated waste management strategy. A full-scale field experiment was performed at the Bisasar Road Landfill Site in Durban to assess the influence of climate, waste composition and operational conditions on the process. A test windrow was constructed and measurements of temperature and airflow through the material were taken. The process

  15. Extinction and Sky Brightness at Dome C

    NASA Astrophysics Data System (ADS)

    Faurobert, M.; Arnaud, J.; Vernisse, Y.

    2012-06-01

    We have installed a small telescope to monitor the sky brightness around the sun at the French-Italian station Concordia at Dome C in Antarctica. Previous campaigns have been performed with the same instrument at Haleakala in Hawai and Sunspot in New Mexico. We compare here the results of the first year of the campaign at Dome C (2008) to the purest sky observed at Haleakala. We show that Dome C is an outstanding site for coronal observations. Compared to Haleaka, it appears to be more transparent, and to contain less aerosols. Its water vapour content is also significantly smaller. These results still have to be confirmed by the analysis of the 2009 and 2010 data.

  16. Environmental assessment, Richton Dome site, Mississippi (US)

    SciTech Connect

    none,

    1986-05-01

    The Nuclear Waste Policy Act of 1982 (42 USC Sections 10101-10226) requires the environmental assessment of a potential site to include a statement of the basis for the nomination of a site as suitable for characterization. Volume 2 of this environmental assessment provides a detailed evaluation of the Richton Dome Site and its suitability as the site for a radioactive waste disposal facility under DOE siting guidelines, as well as a comparison of the Richton Dome site with other proposed sites. Evaluation of the Richton Dome site is based on the reference repository design, but the evaluation will not change if based on the Mission Plan repository concept. The comparative evaluation of proposed sites is required under DOE guidelines, but is not intended to directly support the subsequent recommendation of three sites for characterization as candidate sites. 428 refs., 24 figs., 62 tabs. (MHB)

  17. Propagation of polarised light in bent hi-bi spun fibres

    SciTech Connect

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P

    2015-11-30

    The evolution of polarisation states (PS's) of broadband light propagating through a bent optical fibre with a helical structure of its refractive index anisotropy (hi-bi spun fibre) has been studied theoretically and experimentally. It has been shown that there exists a coordinate system of PS's in which the differential Jones matrix can be replaced by a diagonal matrix, which allows the polarisation parameters of the output broadband light to be readily calculated with sufficient accuracy. We have derived a formula for evaluating the magneto-optical sensitivity of a bent spun fibre. An approach has been proposed for restoring the degree of polarisation of light in a bent hi-bi spun fibre and, as a consequence, the visibility (contrast) of the interferometer in a current sensor with a sensing element based on the fibre under consideration. (optical fibres)

  18. Open-foldable domes with high-tension textile membranes: The GREGOR dome

    NASA Astrophysics Data System (ADS)

    Hammerschlag, R. H.; Kommers, J. N.; Visser, S.; Bettonvil, F. C. M.; van Schie, A. G. M.; van Leverink, S. J.; Sliepen, G.; Jägers, A. P. L.; Schmidt, W.; Volkmer, R.

    2012-11-01

    Double layers of high-tensioned textile membranes were applied to the completely open-foldable dome for the GREGOR telescope for the first time. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulating capability of this double-layer construction. The GREGOR dome is the result of the continuation of the ESO research on open-foldable domes with textile structures, followed by the research for the DOT dome with high-tensioned textile membranes. It cleared the way to extreme stability required for astronomical practice on high mountain sites with heavy storms and ice formation. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR caused no problems, nor did other storms afterwards. Opening and closing experiences up to wind speeds of 90 km/h were without problems. New technical developments were implemented and tested at the GREGOR dome, opening the way for application to much larger domes up to the 30 m diameter-class range.

  19. Lotuce: A new monitor for turbulence characterization inside telescope's dome

    NASA Astrophysics Data System (ADS)

    Ziad, Aziz; Dali Ali, Wassila; Borgnino, Julien; Sarazin, Marc; Buzzoni, Bernard

    2013-12-01

    A new concept of an instrument, Lotuce, dedicated to measure the turbulence inside the dome has been developed jointly with ESO. It consists of using parallel laser beams separated by non redundant baselines between 0.1 and 2-3m and measuring Angle-of-Arrival (AA) fluctuations from spots displacements on a CCD. We use weighted least-square method to fit the measured AA longitudinal and transverse covariances with theoretical forms deduced from the usual models of turbulence. Then, the whole parameters characterizing this turbulence are provided from a complete spatio-temporal analysis of AA fluctuations. The first results of this new instrument are presented and discussed.

  20. Evaluation of dome-input geometry for pyroelectric detectors

    NASA Astrophysics Data System (ADS)

    Zeng, J.; Hanssen, L. M.; Eppeldauer, G. P.

    2013-06-01

    Dome-input pyroelectric radiometers with different black coatings were developed to extend the spectral responsivity scale from near infrared (NIR) to 20 μm. The reflective dome with shiny gold-coating has been known to be an efficient light trap to enhance the detector absorptance and to minimize spectral responsivity variation. The enhancement of spectral responsivity using reflective dome relies on optical characterization of black coating on detector, reflectance of dome reflector, and input aperture dimension, etc. We report a comparison of spectral responsivity of dome-input pyroelectric radiometers measured with/without dome-trap from 2.4 μm to 14 μm using the Infrared Spectral Comparator Facility (IRSCF) at NIST. The results show 4 % to 8 % gain of responsivity for two dome-input pyroelectric detectors, with reduced structure of spectral responsivity. The uncertainty of dome-input pyroelectric radiometer calibrations is approximately 2 % (k = 2).

  1. FIRST OBSERVATIONS OF A DOME-SHAPED LARGE-SCALE CORONAL EXTREME-ULTRAVIOLET WAVE

    SciTech Connect

    Veronig, A. M.; Muhr, N.; Kienreich, I. W.; Temmer, M.; Vrsnak, B.

    2010-06-10

    We present first observations of a dome-shaped large-scale extreme-ultraviolet coronal wave, recorded by the Extreme Ultraviolet Imager instrument on board STEREO-B on 2010 January 17. The main arguments that the observed structure is the wave dome (and not the coronal mass ejection, CME) are (1) the spherical form and sharpness of the dome's outer edge and the erupting CME loops observed inside the dome; (2) the low-coronal wave signatures above the limb perfectly connecting to the on-disk signatures of the wave; (3) the lateral extent of the expanding dome which is much larger than that of the coronal dimming; and (4) the associated high-frequency type II burst indicating shock formation low in the corona. The velocity of the upward expansion of the wave dome (v {approx} 650 km s{sup -1}) is larger than that of the lateral expansion of the wave (v {approx} 280 km s{sup -1}), indicating that the upward dome expansion is driven all the time, and thus depends on the CME speed, whereas in the lateral direction it is freely propagating after the CME lateral expansion stops. We also examine the evolution of the perturbation characteristics: first the perturbation profile steepens and the amplitude increases. Thereafter, the amplitude decreases with r {sup -2.5{+-}0.3}, the width broadens, and the integral below the perturbation remains constant. Our findings are consistent with the spherical expansion and decay of a weakly shocked fast-mode MHD wave.

  2. Water recycling at the Millennium Dome.

    PubMed

    Hills, S; Smith, A; Hardy, P; Birks, R

    2001-01-01

    Thames Water is working with the New Millennium Experience Company to provide a water recycling system for the Millennium Dome which will supply 500 m3/d of reclaimed water for WC and urinal flushing. The system will treat water from three sources: rainwater--from the Dome roof greywater--from handbasins in the toilet blocks groundwater--from beneath the Dome site The treatment technologies will range from "natural" reedbeds for the rainwater, to more sophisticated options, including biological aerated filters and membranes for the greywater and groundwater. Pilot scale trials were used to design the optimum configuration. In addition to the recycling system, water efficient devices will be installed in three of the core toilet blocks as part of a programme of research into the effectiveness of conservation measures. Data on water usage and customer behaviour will be collected via a comprehensive metering system. Information from the Dome project on the economics and efficiency of on-site recycling at large scale and data on water efficient devices, customer perception and behaviour will be of great value to the water industry. For Thames Water, the project provides vital input to the development of future water resource strategies.

  3. Osteochondral Lesions of the Talar Dome.

    PubMed

    Stone

    1996-03-01

    Osteochondral lesions of the talar dome are relatively common causes of ankle pain and disability. Trauma is the most common cause, but ischemic necrosis, en-docrine disorders, and genetic factors may have etiologic significance. Medial lesions are usually located posteriorly on the dome of the talus, whereas lateral lesions are most frequently located anteriorly. Although the staging system described by Berndt and Harty remains popular, it may not accurately reflect the integrity of the articular cartilage. Small lesions of the talar dome may be present despite a normal appearance on plain radiography. Bone scintigraphy may show increased radionuclide uptake in the talar dome. Magnetic resonance imaging is also sensitive for identifying intraosseous abnormalities in the talus and has the added benefit of revealing other types of soft-tissue lesions not visible on routine radiographic studies. Computed tomography remains the imaging technique of choice when delineation of a bone fragment is desired. Nonoperative management of osteochondral lesions, including restricted weight-bearing and/or immobilization, is recommended unless a loose fragment is clearly present. Surgical options include drilling (usually reserved for intact lesions), debridement of the lesion with curettage or abrasion of the bone bed, internal fixation of the fragment, and bone grafting. Recent technical advances allow these procedures to be performed arthroscopically, with potential reduction of surgical trauma, length of hospital stay, and complication rates.

  4. The Urban Dust Dome: A Demonstration Model

    ERIC Educational Resources Information Center

    Cross, Ralph D.

    1973-01-01

    Working plans for an inexpensive urban dust dome model are presented together with some generalizations about urban atmosphere pollution. Theories and principles of atmospheric pollution which are introduced can be made meaningful to elementary students through classroom use of this model. (SM)

  5. Small domes on Venus - Characteristics and origin

    NASA Technical Reports Server (NTRS)

    Aubele, Jayne C.; Sliuta, E. N.

    1990-01-01

    The areal and size-frequency distribution, abundance, individual characteristics, and geologic and regional associations of small domes in the Venera data set are examined. It is noted that, because of their numbers and widespread occurence, regardless of origin, these structures will be important in the local and global geographic interpretation of the surface. It is concluded that small domes of 20 km in diameter occur in numbers of order 10,000 on the northern quarter of the surface of Venus, and that small domes are interpreted to be predominantly low shield volcanos and to represent multiple centralized effusive eruptions of discrete volumes over finite periods. It is noted that small domes occur throughout the northern latitudes, but attain maximum regional concentrations in two areas, one located north of Thetis Regio in Akkruva Colles, and another located on the northeast flanks of Beta Regio in Guinevere Planitia. The presence of two global concentrations implies that magma production and eruption were enhanced within these two areas.

  6. Small domes on Venus - Characteristics and origin

    NASA Astrophysics Data System (ADS)

    Aubele, Jayne C.; Sliuta, E. N.

    1990-12-01

    The areal and size-frequency distribution, abundance, individual characteristics, and geologic and regional associations of small domes in the Venera data set are examined. It is noted that, because of their numbers and widespread occurence, regardless of origin, these structures will be important in the local and global geographic interpretation of the surface. It is concluded that small domes of 20 km in diameter occur in numbers of order 10,000 on the northern quarter of the surface of Venus, and that small domes are interpreted to be predominantly low shield volcanos and to represent multiple centralized effusive eruptions of discrete volumes over finite periods. It is noted that small domes occur throughout the northern latitudes, but attain maximum regional concentrations in two areas, one located north of Thetis Regio in Akkruva Colles, and another located on the northeast flanks of Beta Regio in Guinevere Planitia. The presence of two global concentrations implies that magma production and eruption were enhanced within these two areas.

  7. Dome Storage of Farmer Stock Peanuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The small-scale farmer stock storage research facility at the National Peanut Research Laboratory in Dawson, GA consisting of four warehouses and four monolithic domes was used to conduct a 3-yr study looking at the effects of storing peanuts through the summer months following harvest. The study wa...

  8. After-Hours Science: Gee, A Dome!

    ERIC Educational Resources Information Center

    Santos, John G.

    1984-01-01

    Nature's Classroom (Southbridge, MA), which provides field experiences, academic classes, and activities in the natural sciences, has been recognized as an outstanding program by the National Science Teachers Association's Search for Excellence in Science Education project. Various program activities (including building a geodesic dome) are…

  9. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Specifications for Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have...

  10. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  11. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  12. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  13. 49 CFR 178.255-3 - Expansion domes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Expansion domes. 178.255-3 Section 178.255-3 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... Portable Tanks § 178.255-3 Expansion domes. (a) Expansion domes, if applied, must have a minimum...

  14. Effects of lava-dome emplacement on the Mount St. Helens crater glacier

    NASA Astrophysics Data System (ADS)

    Walder, J. S.; Schilling, S. P.; Denlinger, R. P.; Vallance, J. W.

    2004-12-01

    Since the end of the 1981-1986 episode of lava-dome growth at Mount St. Helens, an unusual glacier has grown rapidly within the crater of the volcano. The glacier, which is fed primarily by avalanching from the crater walls, contains about 30% rock debris by volume, has a maximum thickness of about 220 m and a volume of about 120 million cubic m, and forms a crescent that wraps around the old lava dome on both east and west sides. The new (October 2004) lava dome in the south of the crater began to grow centered roughly on the contact between the old lava dome and the glacier, in the process uplifting both ice and old dome rock. As the new dome is spreading to the south, the adjacent glacier is bulging upward. Firn layers on the outer flank of the glacier bulge have been warped upward almost vertically. In contrast, ice adjacent to the new dome has been thoroughly fractured. The overall style of deformation is reminiscent of that associated with salt-dome intrusion. Drawing an analogy to sand-box experiments, we suggest that the glacier is being deformed by high-angle reverse faults propagating upward from depth. Comparison of Lidar images of the glacier from September 2003 and October 2004 reveals not only the volcanogenic bulge but also elevated domains associated with the passage of kinematic waves, which are caused by glacier-mass-balance perturbations and have nothing to do with volcanic activity. As of 25 October 2004, growth of the new lava dome has had negligible hydrological consequences. Ice-surface cauldrons are common consequences of intense melting caused by either subglacial eruptions (as in Iceland) or subglacial venting of hot gases (as presently taking place at Mount Spurr, Alaska). However, there has been a notable absence of ice-surface cauldrons in the Mount St. Helens crater glacier, aside from a short-lived pond formed where the 1 October eruption pierced the glacier. We suggest that heat transfer to the glacier base is inefficient because

  15. Shape and thermal modeling of the possible cryovolcanic dome Ganesa Macula on Titan: Astrobiological implications

    NASA Astrophysics Data System (ADS)

    Neish, C. D.; Lorenz, R. D.; O'Brien, D. P.; Cassini RADAR Team

    2005-08-01

    Observations of Titan by the Cassini spacecraft have revealed to us a world with an intricate and varied geology. In particular, there is evidence of extensive cryovolcanism. The 180 km structure Ganesa Macula observed in SAR imaging from Cassini's TA encounter in October 2004 resembles the pancake domes seen on Venus by the Magellan spacecraft and is comparable (in terms of years of planetary heatflow required to melt the lava volume) with the Deccan Traps on Earth. Cryovolcanism has important astrobiological implications, as it provides a means of exposing surface organics to liquid water. Aqueous chemistry permits Titan's hydrocarbons and nitriles to form more evolved and oxidized prebiotic species, such as amino acids and pyrimidines. In this work, we use Titan's observed backscatter function to model the radar appearance of domes of various shapes and heights to compare with the image of Ganesa: the SAR data are better fit by a ``spreading viscous drop" (``Huppert") shape than by one constrained by a skin strength (``Nye"). We then model the freezing of the model dome using a finite-element heat conduction code. Estimation of the dome height is presently underway, but even a dome only 1 km in height takes some 5 x 103 years to freeze for lava made entirely of liquid water, and 12 x 103 years for lava made of ammonia dihydrate. These timescales open a window for prebiotic chemistry far wider than can be explored in terrestrial laboratory experiments. This work was supported by the Cassini project.

  16. Relationships of cotton fiber properties to ring-spun yarn quality on selected High Plains cottons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to evaluate the adequacy of High Volume Instruement (HVI) and Advanced Fiber Information System (AFIS) fiber quality parameters for predicting quality parameters of ring-spun yarns considering differences in harvest method. Fiber properties measured using the HVI (...

  17. Solution blow spun Poly(lactic acid)/Hydroxypropyl methylcellulose nanofibers with antimicrobial properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) nanofibers containing hydroxypropyl methylcellulose (HPMC) and tetracycline hydrochloride (THC) were solution blow spun from two different solvents, chloroform/acetone (CA, 80:20 v/v) and 2,2,2-triflouroethanol (TFE). The diameter distribution, chemical, thermal, thermal stab...

  18. Textural evidence for origin of salt dome anhydrite cap rocks, Winnfield Dome, Louisiana

    SciTech Connect

    Ulrich, M.R.; Kyle, J.R.; Price, P.E.

    1985-02-01

    Textures within anhydrite cap rock are products of repeated cycles of halie dissolution and residual anhydrite accretion at tops of salt stocks. Quarrying operations at Winnfield dome have exposed extensive portions of the anhydrite cap rock zone. This zone is composed primarily of unoriented, xenoblastic anhydrite crystals in laminae less than 1 mm to several centimeters thick. Laminations are defined by thin, dark sulfide accumulations and pressure solution of anhydrite. Deformed, banded anhydrite clasts are contained locally within laminae. Multiple-laminated, concave downward anhydrite mounds occur along some horizons. They may contain anhydrite breccia fragments or sulfides. Coarsely crystalline salt mounds, containing disseminated idioblastic anhydrite also occur along horizons. Mound morphologies vary from tall and thin to broad and squat; maximum dimensions range from less than 0.5 to about 2.0 m. These moundlike structures are related spatially and genetically. Moundlike structures are believed to form from salt spines along the salt-anhydrite contact. As the spine dissolves through several cycles of dissolution and accretion, a laminated anhydrite mound is preserved; if the spine becomes isolated from dissolution, then a salt inclusion is preserved. Anhydrite beds within the Louann Salt, deformed during diapirism, are preserved as deformed anhydrite clasts. Steeply dipping, bedded anhydrite zones within the salt stock may produce brecciated anhydrite mounds when incorporated into the cap rock. Sulfides record the movement of metalliferous fluids through the salt-anhydrite contact.

  19. Volcanism on Venus: Large shields and major accumulations of small domes

    NASA Technical Reports Server (NTRS)

    Schaber, Gerald G.; Kozak, Richard C.

    1989-01-01

    The outer layers of the Venusian lithosphere appear to dissipate heat from the interior through mantle-driven thermal anomalies (hot spots, swells). As a result, Venus exhibits diverse forms of thin-skin tectonism and magmatic transfer to and extrusion from countless numbers of volcanic centers (e.g., shields, paterae, domes) and volcano-tectonic complexes (e.g., coronae, arachnoids). What is known about the distribution and morphologies of major Venusian shields is summarized, and the evidence for possible structural control of major accumulations as long as 5000 km of small volcanic domes is described.

  20. Fiber-optic gyro location of dome azimuth

    NASA Astrophysics Data System (ADS)

    Kuehne, John W.

    2016-07-01

    The 2.1-m Otto Struve Telescope, world's second largest in 1939, today has modern motion control and superb tracking, yet the 19-m-diameter Art Deco dome has resisted many attempts to record its azimuth electronically. Demonstrated in January 2016, a small tactical-grade fiber-optic gyro located anywhere on the rotating structure, aided by a few fiducial points to zero gyro drift, adequately locates the azimuth. The cost of a gyro is practically independent of dome size, offering an economical solution for large domes that cannot be easily encoded with conventional systems. The 100-Hz sampling is capable of revealing anomalies in the rotation rate, valuable for preventive maintenance on any dome. I describe software methods and time series analysis to integrate angular velocity to dome azimuth; transformation of telescope hour angle and declination into required dome azimuth, using a formula that accounts for a cross-axis mount inside an offset dome; and test results.

  1. The tectono-thermal evolution of the Waterbury dome, western Connecticut, based on U-Pb and 40Ar/39Ar ages

    USGS Publications Warehouse

    Dietsch, Craig; Kunk, Michael J.; Aleinikoff, John; Sutter, John F.

    2010-01-01

    Level 3 nappes were emplaced over the Waterbury dome along an Acadian décollement synchronous with the formation of a D3 thrust duplex in the dome. The décollement truncates the Ky + Kfs-in (migmatite) isograd in the dome core and a St-in isograd in level 3 nappes, indicating that peak metamorphic conditions in the dome core and nappe cover rocks formed in different places at different times. Metamorphic overgrowths on zircon from the felsic orthogneiss in the Waterbury dome have an age of 387 ± 5 Ma. Rocks of all levels and the décollement are folded by D4 folds that have a strongly developed, regional crenulation cleavage and D5 folds. The Waterbury dome was formed by thrust duplexing followed by fold interference during the Acadian orogeny. The 40Ar/39Ar ages of amphibole, muscovite, biotite, and K-feldspar from above and below the décollement are ca. 378 Ma, 355 Ma, 360 Ma (above) and 340 (below), and 288 Ma, respectively. Any kilometer-scale vertical movements between dome and nappe rocks were over by ca. 378 Ma. Core and cover rocks of the Waterbury dome record synchronous, post-Acadian cooling.

  2. Charged nano-domes and bubbles in epitaxial graphene

    NASA Astrophysics Data System (ADS)

    Ben Gouider Trabelsi, A.; Kusmartsev, F. V.; Robinson, B. J.; Ouerghi, A.; Kusmartseva, O. E.; Kolosov, O. V.; Mazzocco, R.; Gaifullin, Marat B.; Oueslati, M.

    2014-04-01

    For the first time, new epitaxial graphene nano-structures resembling charged ‘bubbles’ and ‘domes’ are reported. A strong influence, arising from the change in morphology, on the graphene layer’s electronic, mechanical and optical properties has been shown. The morphological properties of these structures have been studied with atomic force microscopy (AFM), ultrasonic force microscopy (UFM) and Raman spectroscopy. After initial optical microscopy observation of the graphene, a detailed description of the surface morphology, via AFM and nanomechanical UFM measurements, was obtained. Here, graphene nano-structures, domes and bubbles, ranging from a few tens of nanometres (150-200 nm) to a few μm in size have been identified. The AFM topographical and UFM stiffness data implied the freestanding nature of the graphene layer within the domes and bubbles, with heights on the order of 5-12 nm. Raman spectroscopy mappings of G and 2D bands and their ratio confirm not only the graphene composition of these structures but also the existence of step bunching, defect variations and the carrier density distribution. In particular, inside the bubbles and substrate there arises complex charge redistribution; in fact, the graphene bubble-substrate interface forms a charged capacitance. We have determined the strength of the electric field inside the bubble-substrate interface, which may lead to a minigap of the order of 5 meV opening for epitaxial graphene grown on 4H-SiC face-terminated carbon.

  3. Sediment distribution about salt domes and ridges on Louisiana slope

    SciTech Connect

    Lowrie, A.

    1984-09-01

    Salt ridges and domes underlie much of the present Louisiana slope. The bathymetric expression of underlying salt could be either a mound or a flattening of the normal rate of descent down the slope. The mounded salt features form barriers to the gravity-driven sediments from the shelf break. Much industrial research has been done in the search for reservoir sands about such an obstruction. Parallel-bedded sediments from foredrifts on the upcurrent side of a seamount. These foredrift sediments were deposited where the prevailing ocean bottom currents were locally decelerated by the obstructing seamount. Moats are found on the sides of the obstruction and are the result of erosion or nondeposition owing to acceleration of deflected waters. Leedrifts are found on the downcurrent side of the obstruction. Current gyres result from deceleration of accelerated currents along the obstruction's flanks, and a complex sedimentation pattern results. Flow over the obstruction's top is determined by size and shape of the obstruction relative to size and velocity of the bottom-following current. A turbulent wave will be set up which may have sufficient amplitude to influence sedimentation on the downcurrent side. If ocean bottoms currents equal gravity-driven terrigenous sediment movement and seamounts equal salt domes and ridges, then the result of deep ocean surveys are directly applicable to sedimentation on slopes with underlying salt basement. The salt-related sedimentation pattern of the present slope should be applicable to similar paleoenvironments.

  4. 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

  5. Remote Control of the CFHT Dome Shutter

    NASA Astrophysics Data System (ADS)

    Look, Ivan; Roberts, Larry; Vermeulen, Tom; Taroma, Ralph; Matsushige, Grant

    2011-03-01

    Several years ago CFHT proposed developing a Remote Observing Environment aimed at producing Science Observations at their Facility on Mauna Kea from their Headquarters in Waimea, HI. This Remote Observing Project commonly referred to as OAP (Observatory Automation Project) was completed at the end of January 2011 and has been providing the majority of Science Data since. My poster will attempt to provide Design Information on the Dome Shutter, which is both Controlled and Monitored Remotely from Waimea. The Dome Shutter Control System incorporates an upgraded Allen-Bradley PLC processor (SLC 5/05), which provides Remote Operation and Monitoring of the existing System. Several earlier upgrade projects were integrated to provide improvement to the Shutter System such as PLC Control, System Feedback, and Safety Features. This particular upgrade provides Remote capability, CFHT developed Control GUI, and Remote monitoring that promise to deliver a more versatile, visual, and safer Shutter Operation. The Dome Shutter Control System provides three modes of Operation namely; Remote, Integration, and Local. The Control GUI is used to operate the Shutter remotely. Integration mode is provided to develop PLC software code and is performed by connecting a Laptop directly to the Shutter Control Panel. Local mode is retained to provide Remote Lockout (No Remote Control), which allows Shutter control ONLY via the existing Electrical Panel. This mode is primarily intended for Shutter maintenance and troubleshooting. The Dome Shutter remains the first Line-of-Defense for Telescope protection due to inclement weather and so special attention was considered during Remote development. The Shutter has been equipped with an Autonomous Shutdown sequence in the event of Power or Network failure. If Loss of HELCO Power or Start-up of our Stand-by Diesel Generator is detected; a planned timing sequence will Close the Shutter Automatically. Likewise, an internal CFHT Network heartbeat was

  6. MROI Array telescopes: the relocatable enclosure domes

    NASA Astrophysics Data System (ADS)

    Marchiori, G.; Busatta, A.; Payne, I.

    2016-07-01

    The MROI - Magdalena Ridge Interferometer is a project which comprises an array of up to 10 1.4m diameter mirror telescopes arranged in a "Y" configuration. Each of these telescopes will be housed inside a Unit Telescope Enclosure (UTE) which are relocatable onto any of 28 stations. EIE GROUP Srl, Venice - Italy, was awarded the contract for the design, the construction and the erection on site of the MROI by the New Mexico Institute of Mining and Technology. The close-pack array of the MROI - including all 10 telescopes, several of which are at a relative distance of less than 8m center to center from each other - necessitated an original design for the Unit Telescope Enclosure (UTE). This innovative design enclosure incorporates a unique dome/observing aperture system to be able to operate in the harsh environmental conditions encountered at an altitude of 10,460ft (3,188m). The main characteristics of this Relocatable Enclosure Dome are: a Light insulated Steel Structure with a dome made of composites materials (e.g. glass/carbon fibers, sandwich panels etc.), an aperture motorized system for observation, a series of louvers for ventilation, a series of electrical and plants installations and relevant auxiliary equipment. The first Enclosure Dome is now under construction and the completion of the mounting on site id envisaged by the end of 2016. The relocation system utilizes a modified reachstacker (a transporter used to handle freight containers) capable of maneuvering between and around the enclosures, capable of lifting the combined weight of the enclosure with the telescope (30tons), with minimal impacts due to vibrations.

  7. Numerical Analysis on Double Dome Stretching Tests of Woven Composites

    NASA Astrophysics Data System (ADS)

    Lee, Wonoh; Cao, Jian; Chen, Julie; Sherwood, James

    2007-04-01

    As a result of international corporative benchmark works, material characterization of the woven fabric reinforced composites has been examined to better understand their mechanical properties and to provide the process design information for numerical analysis. Here, in order to predict thermo-forming behaviors of woven composites, the double dome stretching tests have been numerically performed for the balanced plain weave. To account for the change of fiber orientation under the large deformation, the non-orthogonal constitutive model has been utilized and nonlinear friction behavior is incorporated in the simulation. Also the equivalent material properties based on the contact status have been used for the thermo-stamping process. Blank draw-in, punch force history and fiber orientation after forming will be reported.

  8. A Look Inside Rotating Rubble-Pile Asteroids Spun to Disruption

    NASA Astrophysics Data System (ADS)

    Sanchez Lana, Diego; Scheeres, Daniel J.

    2014-11-01

    Driven by the images obtained by different space missions to small asteroids, during the last few years different researchers have used self-gravitating granular mechanics codes for the simulation of small rubble-pile asteroids. One of the many topics of research has been the response of these bodies to rotational evolution due to YORP, specifically the deformation and ultimate disruption of small bodies due to elevated angular velocities.In this research we use self-gravitating aggregates formed by thousands of spheres and a soft-sphere granular dynamics code to explore the effect of the variation of two parameters, friction angle and tensile strength, on their disruption process. The aggregates were slowly spun up to disruption controlling for friction angle, cohesion and global shape. How much each aggregate deformed before disruption was directly related to the angle of friction. The greater it was, the less the aggregate deformed before disruption. Cohesive forces controlled the mode of disruption and maximum spin rate, showing that the aggregates could disrupt by shedding particles or groups of particles from the equatorial region. For high values of tensile strength, the pieces that detached from the initial aggregate were sizable enough for the disruption process to be seen as a fission. This implies that the change from shedding to fission is continuous and therefore, they should not be seen as different processes but just as two ends of the spectrum.A closer look at the spherical aggregates showed that the reshaping of the bodies was not symmetrical. A granular aggregate cannot be completely homogeneous unless its particles are arranged in a crystalline structure, something we avoided. This resulted in an asymmetrically reshaped body, similar to that of 1999 KW4 (at times forming a binary system). For ellipsoidal aggregates, this meant the formation of tear-drop shapes and pairs. The failing of the granular structure is ultimately controlled by the inter

  9. Underwater Calibration of Dome Port Pressure Housings

    NASA Astrophysics Data System (ADS)

    Nocerino, E.; Menna, F.; Fassi, F.; Remondino, F.

    2016-03-01

    Underwater photogrammetry using consumer grade photographic equipment can be feasible for different applications, e.g. archaeology, biology, industrial inspections, etc. The use of a camera underwater can be very different from its terrestrial use due to the optical phenomena involved. The presence of the water and camera pressure housing in front of the camera act as additional optical elements. Spherical dome ports are difficult to manufacture and consequently expensive but at the same time they are the most useful for underwater photogrammetry as they keep the main geometric characteristics of the lens unchanged. Nevertheless, the manufacturing and alignment of dome port pressure housing components can be the source of unexpected changes of radial and decentring distortion, source of systematic errors that can influence the final 3D measurements. The paper provides a brief introduction of underwater optical phenomena involved in underwater photography, then presents the main differences between flat and dome ports to finally discuss the effect of manufacturing on 3D measurements in two case studies.

  10. Fabric and texture at Siple Dome, Antarctica

    USGS Publications Warehouse

    Diprinzio, C.L.; Wilen, L.A.; Alley, R.B.; Fitzpatrick, J.J.; Spencer, M.K.; Gow, A.J.

    2005-01-01

    Preferred c-axis orientations are present in the firn at Siple Dome, West Antarctica, and recrystallization begins as shallow as 200 m depth in ice below -20??C, based on digital analysis of c-axis fabrics, grain-sizes and other characteristics of 52 vertical thin sections prepared in the field from the kilometer-long Siple Dome ice core. The shallowest section analyzed, from 22 m, shows clustering of c axes toward the vertical. By 200 m depth, girdle fabric and other features of recrystallized ice are evident in layers (or regions), separated by layers (regions) of typically finer-grained ice lacking evidence of recrystallization. Ice from about 700-780 m depth, which was deposited during the last ice age, is especially fine-grained, with strongly vertical c axes, but deeper ice shows much larger crystals and strong evidence of recrystallization. Azimuthal asymmetry of some c-axis fabrics, trends in grain-size, and other indicators reveal additional information on processes and history of ice flow at Siple Dome.

  11. Dome corrective osteotomy for cubitus varus deformity.

    PubMed

    Tien, Y C; Chih, H W; Lin, G T; Lin, S Y

    2000-11-01

    Between 1994 and 1998, 15 patients had corrective dome-shaped osteotomy of the humerus for posttraumatic cubitus varus deformity. Thirteen patients had surgery before puberty and two patients had surgery after puberty. In the prepuberty group, all the osteotomies were done by a posterior approach with triceps muscle splitting, and cross pins were used to fix the osteotomy. In the postpuberty group, the osteotomies were done by a posterior approach with olecranon osteotomy, and reconstructive plates were used for fixation. The average followup was 2 years and 4 months. Preoperative carrying angle ranged from 19 degrees to 31 degrees varus (average, 26.2 degrees) and postoperative carrying angle ranged from 7 degrees to 15 degrees valgus (average, 10.7 degrees). No loss of correction was observed and all osteotomies united. The preoperative and postoperative differences of the lateral condylar prominence index ranged from -67% to +6% (average, -30.1%). After reviewing these cases, a dome-shaped osteotomy was found to have the following advantages for correction of cubitus varus deformity: the osteotomy site is more stable than a lateral closing wedge osteotomy for maintaining the correction obtained; the domed osteotomy avoids having the lateral condyle becoming prominent; and the posterior scar is more cosmetically acceptable than the lateral scar in the lateral closing wedge osteotomy.

  12. Geologic and hydrologic summary of salt domes in Gulf Coast region of Texas, Louisiana, Mississippi, and Alabama

    USGS Publications Warehouse

    Anderson, R. Ernest; Eargle, Dolan H.; Davis, Beth O.

    1973-01-01

    There are 263 known or suspected onshore salt domes in the Texas-Louisiana-Mississippi-Alabama portion of the Gulf Coast geosyncline. The top of the salt in 148 of them is probably deeper than desirable for a waste repository site, and 79 of those that are shallow enough are probably unavailable for a site because of present use by industry for gas storage or production of oil, salt, or sulfur. In this report we have compiled the available geologic and hydrologic background data pertinent to the evaluation of the remaining 36 known or suspected salt domes as potential sites for waste storage. There are three parts to this compilations: 1) summaries of the geology and hydrology of the salt-dome province as a whole; 2) summaries of the physiography, climate, geology, and hydrology of each of the five salt-dome basins that occur within the province; and 3) an appendix of background data for each of the 36 potentially acceptable domes. The distribution of salt domes in the province is genetically related to areas of relative subsidence that formed basins or depocenters within the Gulf Coast geosyncline. In some cases, as in northeast Texas and south Louisiana, the locations of individual domes or groups of domes are related to deep movement of salt along axial trends. The salt domes in the interior salt-dome subprovince are probably more structurally stable than those of the coastal subprovince because salt diapirism is inferred to have ceased around Miocene time in the interior but may still be active in parts of the coastal subprovince. Although the size and shape of many domes is unknown or can only be roughly approximated, each of the five basins in the province appears to contain potentially acceptable domes of adequate size for a repository. We recognize no pattern to the distribution of salt-dome size. Caprock thicknesses vary greatly within each salt-dome basin,and we recognize no pattern to the variations. Among the potentially acceptable domes, the depths to

  13. Volcano-tectonic control of Merapi's lava dome splitting observed from high resolution TerraSAR-X data

    NASA Astrophysics Data System (ADS)

    Luehr, Birger-G.; Walter, Thomas R.; Subandriyo, Joko; Sri Brotopuspito, Kirbani; Vasyura-Bathke, Hannes; Suryanto, Wiwit; Aisyah, Naning; Darmawan, Herlan; Nikkhoo, Mehdi; Richter, Nicole; Jousset, Philippe; Dahm, Torsten

    2015-04-01

    Volcanism at active andesite-dacite volcanoes is often associated with the formation and collapse of circular shaped protrusions of extruded, highly viscous lava, the so-called domes, which are emplaced in the near summit region. Growing domes may experience stable and instable structural phases, with a gradual transition in between. Dome collapse and the break-off of instable blocks of viscous lava may lead to pyroclastic flows, one of the most lethal hazards at stratovolcanoes. At Merapi volcano, Indonesia, nearly 50 % of all eruptions are accompanied by these phenomena. After the climactic eruption in 2010 which left an amphitheater in the summit region, a new dome started growing. Three years later, the dome reached a height of approximately 100 m and diameters of 220 and 190 m with a plateau-like surface area of 40,000m2 approximately. On 18/11/2013, an explosion occurred without identified precursors, leaving a major fracture cutting the complete dome structure. Based on high resolution TerraSAR-X satellite radar imagery, we could identify this linear fracture, traceable over ~200m in the long axis, and up to 40m width. After geocoding of the radar amplitude imagery, the fractures azimuthal trend could be compared to other structural lineaments, indicative of a significant NNW-SSE structural direction that has formed on Merapi volcano in the past. This alignment is also visible in a seismic velocity tomographic imagery for the upper crust, down to 15 km depth. The Merapi dome fractured in a NW-SE direction, and is consistent with the alignment of regional tectonic structures and of anticipated directions of pyroclastic flows. The fracture may be part of a larger volcano-tectonic system and may affect the dynamics and the stability of the Merapi dome.

  14. Temporal evolution of magma flow and degassing conditions during dome growth, insights from 2D numerical modeling

    NASA Astrophysics Data System (ADS)

    Chevalier, Laure; Collombet, Marielle; Pinel, Virginie

    2017-03-01

    Understanding magma degassing evolution during an eruption is essential to improving forecasting of effusive/explosive regime transitions at andesitic volcanoes. Lava domes frequently form during effusive phases, inducing a pressure increase both within the conduit and within the surrounding rocks. To quantify the influence of dome height on magma flow and degassing, we couple magma and gas flow in a 2D numerical model. The deformation induced by magma flow evolution is also quantified. From realistic initial magma flow conditions in effusive regime (Collombet, 2009), we apply increasing pressure at the conduit top as the dome grows. Since volatile solubility increases with pressure, dome growth is then associated with an increase in magma dissolved water content at a given depth, which corresponds with a decrease in magma porosity and permeability. Magma flow evolution is associated with ground deflation of a few μrad in the near field. However this signal is not detectable as it is hidden by dome subsidence (a few mrad). A Darcy flow model is used to study the impact of pressure and permeability conditions on gas flow in the conduit and surrounding rock. We show that dome permeability has almost no influence on magma degassing. However, increasing pressure in the surrounding rock, due to dome loading, as well as decreasing magma permeability in the conduit limit permeable gas loss at the conduit walls, thus causing gas pressurization in the upper conduit by a few tens of MPa. Decreasing magma permeability and increasing gas pressure increase the likelihood of magma explosivity and hazard in the case of a rapid decompression due to dome collapse.

  15. Where is the Best Site on Earth? Domes A, B, C, and F, and Ridges A and B

    NASA Technical Reports Server (NTRS)

    Suanders, Will; Lawrence, Jon S.; Storey, John W. V.; Ashley, Michael C. B.; Kato, Seiji; Minnis, Patrick; Winker, David M.; Liu, Guiping; Kulesa, Craig

    2009-01-01

    The Antarctic plateau contains the best sites on earth for many forms of astronomy, but none of the existing bases were selected with astronomy as the primary motivation. In this paper, we try to systematically compare the merits of potential observatory sites. We include South Pole, Domes A, C and F, and also Ridge B (running NE from Dome A), and what we call Ridge A (running SW from Dome A). Our analysis combines satellite data, published results and atmospheric models, to compare the boundary layer, weather, free atmosphere, sky brightness, pecipitable water vapour, and surface temperature at each site. We find that all Antarctic sites are likely compromised for optical work by airglow and aurorae. Of the sites with existing bases, Dome A is the best overall; but we find that Ridge A offers an even better site. We also find that Dome F is a remarkably good site. Dome C is less good as a thermal infrared or terahertz site, but would be able to take advantage of a predicted OH hole over Antarctica during Spring.

  16. PP/POSS Nanocomposites: Characterization and Properties of Melt Spun Fibers

    NASA Astrophysics Data System (ADS)

    Lee, Byoung-Jo; Roy, Sayantan; Jana, Sadhan

    2009-03-01

    It is known that molecules of polyhedral oligomeric silsesquioxane (POSS) can self-assemble into spherical, fibrillar, or lamellar nanoparticles by bottom-up self assembly process during mixing with host polymers. This study capitalizes on such nanoparticle formation to increase the melt strength and tensile properties of polyolefin blown films and spun fibers. A novel method was developed whereby a sorbitol-type nucleating agent was used as dispersion aids for POSS. The nucleating agent also served as templates for self-assembly of POSS molecules into nanoparticles of 25-200 nm in diameter. A typical polypropylene formulation containing 0.3 wt% nucleating agent and 5-10 wt% POSS was spun into fibers with close to 70% reduction in diameter and 40-45% increase in modulus and 70-75% increase in yield strength compared to unfilled PP. An optimum concentration of POSS was identified.

  17. Inherent temperature compensation of fiber-optic current sensors employing spun highly birefringent fiber.

    PubMed

    Müller, G M; Gu, X; Yang, L; Frank, A; Bohnert, K

    2016-05-16

    We investigate the various contributions to the temperature dependence of an interferometric fiber-optic current sensor employing spun highly-birefringent sensing fiber, in particular, the contributions from the fiber retarder at the fiber coil entrance, the spun fiber's birefringence, and the Faraday effect. We theoretically and experimentally demonstrate that an appropriately designed retarder inherently compensates the temperature dependence of the fiber birefringence and the Faraday effect. We demonstrate insensitivity to temperature to within ± 0.2% between -40 and + 85 °C. Furthermore, we analyze the influence of the retarder parameters on the linearity of the recovered magneto-optic phase shift vs. current and determine a set of parameters that results in a perfectly linear relationship.

  18. A New Approach to Inferences for Pancake Domes on Venus

    NASA Technical Reports Server (NTRS)

    Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.

    2008-01-01

    Figure 1 shows a radar image and topography for flat-topped, steep-sided "pancake" domes on Venus. At least 145 such domes have been identified on Venus [I] and are thought to be volcanic in origin [2]. Based on analysis of the dome surfaces, [3] suggested that only the late stage surface fractures are preserved, indicating entrainment and annealing of fractures during emplacement, consistent with a basaltic composition. Figure 1 shows a radar image and topography for flat-topped, steep-sided "pancake" domes on Venus. At least 145 such domes have been identified on Venus [I] and are thought to be volcanic in origin [2]. Based on analysis of the dome surfaces, [3] suggested that only the late stage surface fractures are preserved, indicating entrainment and annealing of fractures during emplacement, consistent with a basaltic composition.

  19. Conformal dome aberration correction by designing the inner surface

    NASA Astrophysics Data System (ADS)

    Zhang, Wang; Chen, Shouqian; Fan, Zhigang

    2016-12-01

    The ray transmission models of optical domes were established, and the characteristics of the rays while passing through a hemispherical dome and a conformal dome were comparatively analysed. Acquiring the minimum deviated angles from the inner surface of the conformal dome was then determined to be the designing goal for reducing the dynamic aberrations. Based on this, the inner surface of the conformal dome was optimized and thus, the dynamic aberrations were reduced. Finally, a completely cooled conformal optical system was designed. The results show that the optical system have produced good imaging quality within all the fields of regard, which further illustrates that designing the inner surface of a conformal dome is an effective method for aberration correction.

  20. Impact Simulation and Analysis of a Glass Ceramic Spherical Dome

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hee; Kim, Jae-Hoon; Lee, Je-Jun; Lee, Young-Shin; Koo, Song-Hoe; Moon, Soon-Il

    The dome port cover of a ramjet engine is used to seal off the ram air inlet during booster operation. When the ramjet engine undergoes the transition leading to ramjet operation phase, the port cover is fragmented by the ram pressure. Lately, the dome port cover has been made using a MACOR glass-filled ceramic that has high heat resistance and high compression strength, as well as low density. In this study, fracture simulations of a ceramic dome under shock pressure were performed through the finite element method, using the nonlinear code LS-DYNA. The material properties of the simulations were applied to the experimental results of a tensile test for the MACOR glass-filled ceramic. The simulation was carried out on the spherical dome model using various impact pulses. The fracture strength and fracture behavior mode were compared for each case. The type-A spherical dome fractured earlier than the other kinds of domes.

  1. Electro-Spun Fine Fibers of Shape Memory Polymer Used as an Engineering Part

    DTIC Science & Technology

    2010-01-28

    control the experimental condition, it was difficult to fabricate the same diameter fibers . However, it was repeatedly confirmed, this paper mesh...fine fibers . By the use of electrospinning , for example, a two-dimensional filter with superior functionality can be easily fabricated. However...individually fabricating fibers is a difficult task for the electrospinning technology, since electro-spun fibers are inevitably entangled and stick

  2. Experimental Battledress Uniform Fabrics Made from Amine Oxide Solvent Spun Cellulosic Fibers

    DTIC Science & Technology

    2002-02-01

    The purpose of this effort is to investigate a new fiber called Tencel and determine if it offers any performance advantages over standard combat...uniform materials. Tencel is an amine oxide solvent spun cellulosic fiber, and is reported to be equal or superior to rayon in many ways and is produced...without causing environmental problems. An experimental 100 percent Tencel fabric was woven in accordance with MIL-C-43468, Cloth, Camouflage Pattern

  3. Identifying suitable "piercement" salt domes for nuclear waste storage sites

    SciTech Connect

    Kehle, R.

    1980-08-01

    Piercement salt domes of the northern interior salt basins of the Gulf of Mexico are being considered as permanent storage sites for both nuclear and chemically toxic wastes. The suitable domes are stable and inactive, having reached their final evolutionary configuration at least 30 million years ago. They are buried to depths far below the level to which erosion will penetrate during the prescribed storage period and are not subject to possible future reactivation. The salt cores of these domes are themselves impermeable, permitting neither the entry nor exit of ground water or other unwanted materials. In part, a stable dome may be recognized by its present geometric configuration, but conclusive proof depends on establishing its evolutionary state. The evolutionary state of a dome is obtained by reconstructing the growth history of the dome as revealed by the configuration of sedimentary strata in a large area (commonly 3,000 square miles or more) surrounding the dome. A high quality, multifold CDP reflection seismic profile across a candidate dome will provide much of the necessary information when integrated with available subsurface control. Additional seismic profiles may be required to confirm an apparent configuration of the surrounding strata and an interpreted evolutionary history. High frequency seismic data collected in the near vicinity of a dome are also needed as a supplement to the CDP data to permit accurate depiction of the configuration of shallow strata. Such data must be tied to shallow drill hole control to confirm the geologic age at which dome growth ceased. If it is determined that a dome reached a terminal configuration many millions of years ago, such a dome is incapable of reactivation and thus constitutes a stable storage site for nuclear wastes.

  4. Small domes on Venus - Probable analogs of Icelandic lava shields

    NASA Technical Reports Server (NTRS)

    Garvin, James B.; Williams, Richard S., Jr.

    1990-01-01

    On the basis of observed shapes and volumetric estimates, small, dome-like features on radar images of Venus are interpreted to be analogs of Icelandic lava-shield volcanoes. Morphometric data for Venusian domes in Aubele and Slyuta as well as measurements of representative dome volumes and areas from Tethus Regio are used to demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS).

  5. Surface valence transformation during thermal activation and hydrogenation thermodynamics of Mg-Ni-Y melt-spun ribbons

    NASA Astrophysics Data System (ADS)

    Zhang, Tiebang; Song, Wenjie; Kou, Hongchao; Li, Jinshan

    2016-05-01

    In this work, phase compositions and chemical valence states on the surface and subsurface of Mg67Ni33-xYx (x = 0, 1, 3, 6) ribbons during thermal activation have been investigated by X-ray photoelectron spectroscopy (XPS). The results indicate that the surface contaminants of melt-spun ribbons are mainly MgO, NiO, Y2O3 and organics. The oxides/hydroxides of Mg67Ni33-xYx (x = 0, 1, 3, 6) melt-spun ribbons are removed from the surface during thermal activation. Surface chemical valence firstly transforms from oxidized state to the metallic one during thermal activation, which accounts for hydrogenation of Mg67Ni33-xYx melt-spun ribbons. Hydrogen absorption capacities of Mg67Ni33-xYx (x = 0, 1, 3, 6) melt-spun ribbons are enhanced with the increase of cycle numbers during thermal activation. Hydrogenation thermodynamics of activated Mg67Ni33-xYx (x = 0, 1, 3, 6) melt-spun ribbons have been also compared and correlated with the surface valence transformation. The obtained enthalpy of hydride formation is -55.5, -50.5, -46.9 and -48.6 kJ/mol for Mg67Ni33-xYx melt-spun ribbons with x = 0, 1, 3 and 6, respectively.

  6. Exhumation of high-pressure rocks in a Variscan migmatite dome (Montagne Noire, France)

    NASA Astrophysics Data System (ADS)

    Whitney, Donna; Roger, Francoise; Rey, Patrice; Teyssier, Christian

    2015-04-01

    of garnet rims presents a challenge for ascribing the zircon rim age to hydrothermal alteration. Of the 5 reported eclogite localities in the MN, 4 are located near a high-strain zone along the long axis of the dome and one is located in a shear zone at the SSW margin of the gneissic core. 2D and 3D numerical models show that migmatite domes may form in response to extension of the upper crust, as the partially molten deep crust ascends along a steep, axial high strain zone and then flows into subdomes flanking this zone, forming a double dome such as the MN. This mode of dome formation is an efficient mechanism for rapid exhumation of deep crust. Migmatite dome rocks equilibrate at LP/HT, but eclogite inclusion in migmatite preserve their deep origin, track exhumation, and inform the internal dynamics of domes. Domes like the MN demonstrate that the opportunistic low-viscosity deep crust flows readily to fill gaps created by extensional/ transtensional domains in the collapsing late-Variscan orogen.

  7. Influence of structural parameters on magnetoresistive properties of CuFeNi melt spun ribbons.

    PubMed

    Cazottes, S; Danoix, F; Fnidiki, A; Lemarchand, D; Baricco, M

    2009-04-01

    The microstructure of Cu(80)Fe(10)Ni(10) (at%) granular ribbon was investigated by means of atom probe tomography (APT). A granular system is composed of magnetic precipitates embedded in a non-magnetic matrix. In this ribbon, the magnetic precipitates have a diameter smaller than 5nm in the as-spun state, and their crystallographic structure is very similar to the one of the matrix, which makes it difficult to characterize them using conventional techniques. Those data are of great importance to understand the magnetic and the transport behaviour of these ribbons. Using atom probe tomography, a 3D reconstruction of the microstructure of the as-spun and annealed ribbons was achieved and a precise characterization of the compositions of the two phases and of the composition profile at interfaces was carried out. In the as-spun state the composition of the matrix is Cu(89)Fe(3)Ni(8), the one of the precipitates is Cu(30)Fe(40)Ni(30). Upon annealing, the precipitates get enriched in iron. After annealing at 600 degrees C for 24h, the measured compositions are close to the one predicted by Thermocalc, with Cu(94)Fe(1)Ni(5) for the matrix and Cu(5)Fe(64)Ni(31) for the precipitates.

  8. Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Lazaris, Anthoula; Arcidiacono, Steven; Huang, Yue; Zhou, Jiang-Feng; Duguay, François; Chretien, Nathalie; Welsh, Elizabeth A.; Soares, Jason W.; Karatzas, Costas N.

    2002-01-01

    Spider silks are protein-based ``biopolymer'' filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to ``biomimic'' the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

  9. Numerical Simulation of Textile Composite Stamping On Double Dome

    SciTech Connect

    Xiongqi Peng; Zia Ur Rehman

    2011-05-04

    Stamping is one of the most effective ways to form textile composites in industry for providing high-strength, low-weight and cost-effective products. This paper presents a fully continuum mechanics-based approach for stamping simulation of textile fiber reinforced composites by using finite element (FE) method. A previously developed non-orthogonal constitutive model is used to represent the anisotropic mechanical behavior of textile composites under large deformation during stamping. Simulation are performed on a balanced plain weave composite with 0 deg./90 deg. and {+-}45 deg. as initial yarn orientation over a benchmark double dome device. Simulation results show good agreement with experimental output in terms of a number of parameters selected for comparison.

  10. Gravity measurements on rhyolite domes near the Krafla volcano, North Iceland

    NASA Astrophysics Data System (ADS)

    Agustsdottir, T.; Gudmundsson, M. T.; Einarsson, P.

    2008-12-01

    Krafla is a central volcano in the Northern Volcanic Zone (NVZ) of Iceland. It began forming about 200 000 years BP, has a caldera, and is transected by a N10°A trending fissure swarm. Krafla's products are mostly basaltic but rhyolite domes have formed around the caldera rims. The Krafla area is both easily accessible and one of the most studied areas in northern Iceland due to the geothermal power plant situated above the caldera's shallow magma chamber and the recent volcano-tectonic episode, the Krafla fires in 1975-1984. Silicic rocks in Iceland are generally associated with central volcanoes. Rhyolite magma can rise due to buoyancy forces as a cryptodome to the surface where it erupts. Due to its high viscosity and resistance to flow it often accumulates and forms a lava dome over the vent. Data on density and volumes are essential for meaningful modelling of the emplacement of cryptodomes and lava domes. Such data is scarce. Therefore a gravity survey was carried out in the Krafla area in the autumn of 2007 to determine the mean bulk density values of rhyolite domes and their approximate mass and volume. Profiles were measured over three formations, ranging in size from Hlíðarfjall (310 m high and 2 km long), formed 60 000 years BP, to Hrafntinnuhryggur (80 m high and 2.5 km long) formed 30 000 years BP, to Hraunbunga (125 m high and 1.8 km long) formed 10 000 years BP. Mean bulk density for each formation was obtained by the Nettleton method and the volumes were calculated. Mean bulk density and volumes obtained were, Hlidarfjall: 1600- 1800 kg/m3, 0.14 ± 0.01 km3; Hrafntinnuhryggur: 1600-1900 kg/m3, 0.021 ± 0.002 km3; Hraunbunga: 1800-1900 kg/m3, 0.040 ± 0.004 km3. The mean bulk densities from rock samples collected at the survey area are in good agreement, supporting these findings. All the formations have low density values, reflecting both low grain density and high porosity. The Nettleton profiles demonstrate that these formations are neither

  11. Formation of lunar mare domes along crustal fractures: Rheologic conditions, dimensions of feeder dikes, and the role of magma evolution

    NASA Astrophysics Data System (ADS)

    Wöhler, Christian; Lena, Raffaello; Phillips, Jim

    2007-08-01

    In this study we examine a set of lunar mare domes located in the Hortensius/Milichius/T. Mayer region and in northern Mare Tranquillitatis with respect to their formation along crustal fractures, their rheologic properties, the dimensions of their feeder dikes, and the importance of magma evolution processes during dome formation. Many of these domes display elongated summit vents oriented radially with respect to major impact basins, and several dome locations are also aligned in these preferential directions. Analysis of Clementine UV/VIS and Lunar Prospector gamma ray spectrometer data reveals that the examined mare domes formed from low-Si basaltic lavas of high FeO and low to moderate TiO 2 content. Based on their morphometric properties (diameter, height, volume) obtained by photoclinometric and shape from shading analysis of telescopic CCD images, we derive rheologic quantities (lava viscosity during eruption, effusion rate, duration of the effusion process, magma rise speed) and the dimensions of the feeder dikes. We establish three rheologic groups characterised by specific combinations of rheologic properties and dike dimensions, where the most relevant discriminative parameter is the lava viscosity η. The first group is characterised by 10 Pas<η<10 Pas and contains the domes with elongated vents in the Milichius/T. Mayer region and two similar domes in northern Mare Tranquillitatis. The second group with 10 Pas<η<10 Pas comprises the very low aligned domes in northern Mare Tranquillitatis, and the third group with 10 Pas<η<10 Pas the relatively steep domes near Hortensius and in the T. Mayer region. The inferred dike dimensions in comparison to lunar crustal thickness data indicate that the source regions of the feeder dikes are situated within the upper crust for six of the domes in northern Mare Tranquillitatis, while they are likely to be located in the lower crust and in the upper mantle for the other examined domes. By comparing the time scale

  12. Influence of impurity elements on the nucleation and growth of Si in high purity melt-spun Al-Si-based alloys

    NASA Astrophysics Data System (ADS)

    Li, J. H.; Zarif, M. Z.; Dehm, G.; Schumacher, P.

    2012-11-01

    The nucleation and growth of Si has been investigated by TEM in a series of high purity melt spun Al-5Si (wt%)-based alloys with a trace addition of Fe and Sr. In the as-melt-spun condition, some twinned Si particles were found to form directly from the liquid along the grain boundary. The addition of Sr into Al-5Si-based alloys promotes the twinning of Si particles on the grain boundary and the formation of Si precipitates in the α-Al matrix. The majority of plate-shaped and truncated pyramid-shaped Si precipitates were also found to nucleate and grow along {111}α-Al planes from supersaturated solid solution in the α-Al matrix. In contrast, controlled slow cooling decreased the amount of Si precipitates, while the size of the Si precipitates increased. The orientation relationship between these Si precipitates and the α-Al matrix still remained cube to cube. The β-Al5FeSi intermetallic was also observed, depending on subsequent controlled cooling.

  13. Smooth Muscle Cell Alignment and Phenotype Control by Melt Spun Polycaprolactone Fibers for Seeding of Tissue Engineered Blood Vessels

    PubMed Central

    Agrawal, Animesh; Lee, Bae Hoon; Irvine, Scott A.; An, Jia; Bhuthalingam, Ramya; Singh, Vaishali; Low, Kok Yao; Chua, Chee Kai; Venkatraman, Subbu S.

    2015-01-01

    A method has been developed to induce and retain a contractile phenotype for vascular smooth muscle cells, as the first step towards the development of a biomimetic blood vessel construct with minimal compliance mismatch. Melt spun PCL fibers were deposited on a mandrel to form aligned fibers of 10 μm in diameter. The fibers were bonded into aligned arrangement through dip coating in chitosan solution. This formed a surface of parallel grooves, 10 μm deep by 10 μm across, presenting a surface layer of chitosan to promote cell surface interactions. The aligned fiber surface was used to culture cells present in the vascular wall, in particular fibroblasts and smooth muscle cells. This topography induced “surface guidance” over the orientation of the cells, which adopted an elongated spindle-like morphology, whereas cells on the unpatterned control surface did not show such orientation, assuming more rhomboid shapes. The preservation of VSMC contractile phenotype on the aligned scaffold was demonstrated by the retention of α-SMA expression after several days of culture. The effect was assessed on a prototype vascular graft prosthesis fabricated from polylactide caprolactone; VSMCs aligned longitudinally along a fiberless tube, whereas, for the aligned fiber coated tubes, the VSMCs aligned in the required circumferential orientation. PMID:26413093

  14. Mechanical behaviour of dacite from Mount St. Helens (USA): A link between porosity and lava dome extrusion mechanism (dome or spine)?

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Russell, J. K.; Kennedy, L. A.

    2016-12-01

    There is a rich diversity in lava dome morphology, from blocky domes and lobes to imposing spine and whaleback structures. The latter extrude via seismically active, gouge-rich conduit-margin faults, a manifestation of a brittle failure mode. Brittle versus ductile behaviour in volcanic rocks is known to be porosity dependent, and therefore offers a tantalising link between the properties of the material near the conduit margin and the extrusion mechanism (dome or spine). We test this hypothesis by complementing published data on the mechanical behaviour of dacites from the 2004-2008 spine-forming eruption at Mount St. Helens (MSH) with new data on dacite lavas collected from the 1980 dome. The 1980 dacite samples were deformed at room temperature under a range of pressures (i.e., depths) to investigate their mechanical behaviour and failure mode (brittle or ductile). Low-porosity dacite (porosity 0.19) is brittle up to an effective pressure of 30 MPa (depth 1 km) and is ductile at 40 MPa (depth 1.5 km). High-porosity dacite (porosity 0.32) is ductile above an effective pressure of 5 MPa (depth 200 m). Samples deformed in the brittle regime show well-developed ( 1 mm) shear fracture zones comprising broken glass and crystal fragments. Samples deformed in the ductile regime feature anastomosing bands of collapsed pores. The combined dataset is used to explore the influence of strain rate, temperature, and porosity on the mechanical behaviour and failure mode of dacite. A decrease in strain rate does not influence the strength of dacite at low temperature, but reduces strength at high temperature (850 °C). Due to the extremely low glass content of these materials, such weakening is attributed to the increased efficiency of subcritical crack growth at high temperature. However, when strain rate is kept constant, temperature does not significant impact strength reflecting the highly crystallised nature of dacite from MSH. Dacite from the 2004-2008 eruption is stronger

  15. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    DOEpatents

    Hill, Mary Ann; Bingert, John F.; Bingert, Sherri A.; Thoma, Dan J.

    1998-01-01

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process.

  16. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    DOEpatents

    Hill, M.A.; Bingert, J.F.; Bingert, S.A.; Thoma, D.J.

    1998-09-08

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process. 5 figs.

  17. Solution-spun hollow fiber polysulfone and polyethersulfone ultrafiltration membranes

    SciTech Connect

    Liu, Tinghui; Zhang, Donghui; Xu, Shunguang; Sourirajan, S. )

    1992-02-01

    Polysulfone hollow fiber membranes are currently in extensive industrial use, either as such for ultrafiltration (UF) applications or as a base for subsequent coating operations for use as gas or vapor separation membranes. A laboratory apparatus for making hollow fiber membranes by the solution spinning process is described. Several hollow fiber membranes form polysulfone (Udel-3500) and polyethersulfone (Victrex) polymers have been made by using the above apparatus. The effects of spin-solution composition, length of air gap, and pressure used for fiber extrusion on fiber dimensions and ultrafiltration performance of the resulting membranes have been studied and are discussed.

  18. Evolution of tuff ring-dome complex: the case study of Cerro Pinto, eastern Trans-Mexican Volcanic Belt

    NASA Astrophysics Data System (ADS)

    Zimmer, Brian W.; Riggs, Nancy R.; Carrasco-Núñez, Gerardo

    2010-12-01

    Cerro Pinto is a Pleistocene rhyolite tuff ring-dome complex located in the eastern Trans-Mexican Volcanic Belt. The complex is composed of four tuff rings and four domes that were emplaced in three eruptive stages marked by changes in vent location and eruptive character. During Stage I, vent clearing produced a 1.5-km-diameter tuff ring that was then followed by emplacement of two domes of approximately 0.2 km3 each. With no apparent hiatus in activity, Stage II began with the explosive formation of a tuff ring ~2 km in diameter adjacent to and north of the earlier ring. Subsequent Stage II eruptions produced two smaller tuff rings within the northern tuff ring as well as a small dome that was mostly destroyed by explosions during its growth. Stage III involved the emplacement of a 0.04 km3 dome within the southern tuff ring. Cerro Pinto's eruptive history includes sequences that follow simple rhyolite-dome models, in which a pyroclastic phase is followed immediately by effusive dome emplacement. Some aspects of the eruption, however, such as the explosive reactivation of the system and explosive dome destruction, are more complex. These events are commonly associated with polygenetic structures, such as stratovolcanoes or calderas, in which multiple pulses of magma initiate reactivation. A comparison of major and trace element geochemistry with nearby Pleistocene silicic centers does not show indication of any co-genetic relationship, suggesting that Cerro Pinto was produced by a small, isolated magma chamber. The compositional variation of the erupted material at Cerro Pinto is minimal, suggesting that there were not multiple pulses of magma responsible for the complex behavior of the volcano and that the volcanic system was formed in a short time period. The variety of eruptive style observed at Cerro Pinto reflects the influence of quickly exhaustible water sources on a short-lived eruption. The rising magma encountered small amounts of groundwater that

  19. Astronaut Alan Bean doing acrobatics in OWS dome area

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, doing acrobatics in the dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. The dome area is about 22 feet in diameter and 19 feet from top to bottom.

  20. The Mairan domes: silicic volcanic constructs on the Moon

    USGS Publications Warehouse

    Glotch, Timothy D.; Hagerty, Justin J.; Lucey, Paul G.; Hawke, B. Ray; Giguere, Thomas A.; Arnold, Jessica A.; Williams, Jean-Pierre; Jolliff, Bradley L.; Paige, David A.

    2011-01-01

    The Mairan domes are four features located in northern Oceanus Procellarum at ∼312.3E, 41.4N on the Moon. High resolution visible imagery, visible-to-mid-IR spectra, and Lunar Prospector Th abundance data all indicate that these four domes have a composition that is consistent with derivation from a Si-rich, highly evolved magma.

  1. Astronaut Jack Lousma doing acrobatics in OWS dome area

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Jack R. Lousma, Skylab 3 pilot, doing acrobatics in the dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. The dome area is about 22 feet in diameter and 19 feet from top to bottom.

  2. SOLUTION MINING IN SALT DOMES OF THE GULF COAST EMBAYMENT

    SciTech Connect

    Griswold, G. B.

    1981-02-01

    Following a description of salt resources in the salt domes of the gulf coast embayment, mining, particularly solution mining, is described. A scenario is constructed which could lead to release of radioactive waste stored in a salt dome via inadvertent solution mining and the consequences of this scenario are analyzed.

  3. Stokes vector imaging of the polarized sky-dome

    NASA Astrophysics Data System (ADS)

    North, J. A.; Duggin, M. J.

    1997-01-01

    A practical method has been developed for obtaining partial Stokes vector (IQU_) and derivative (IPT_) images of the polarized sky-dome. This method takes advantage of a four-lens stereoscopic camera, a dome mirror, photo CD processing, and commercially available digital image-processing software.

  4. Melt spun and suction cast Nd-Fe-Co-B-Nb hard magnets with high Nd contents

    NASA Astrophysics Data System (ADS)

    Cui, X. H.; Liu, Z. W.; Zhong, X. C.; Yu, H. Y.; Zeng, D. C.

    2012-04-01

    Nd-Fe-Co-B-Nb alloys with Nd contents of 9-9.5 at % were prepared by melt spinning and suction casting. It was found from the melt spun ribbon samples that Nb addition enhanced the glass forming ability and Co addition improved the thermal stability. Larger values of Jr and (BH)max were obtained for the ribbon samples than for the bulk ones due to the finer crystalline structure in the former. Nanocrystallite with amorphous structure was found in the suction cast rod samples. The as-cast Nd9Fe71.5B15.5Nb4 rod in a diameter of 2 mm exhibited the best hard magnetic behavior. A remanence of 0.59 T, a coercivity of 1154 kA/m, and a maximum energy product of 54.2 kJ/m3 have been obtained after heat treatment. The distribution of nonmagnetic FeNb phase plays a key role in the improvement of coercivity. Current work suggests that large size Nd2Fe14B/Fe3B nanocomposite magnets with high Nd contents and good magnetic properties can be obtained using a nanocrystalline precursor instead of bulk metallic glass.

  5. Effects of hypersonic vehicle's optical dome on infrared imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenjun; Cao, Zhiguo; Wang, Wenwu

    2011-09-01

    When an optically guided hypersonic vehicle flies in the atmosphere, the scene is viewed through an optical dome. Because of hypersonic friction with the atmosphere, the optical dome is inevitably covered by a serious shock wave, which threatens to alter the dome's physical parameters and further induce wavefront distortion and degradation of images. By studying the physical phenomena occurring within the optical dome in such an adverse environment, this paper identifies the relationship between the variation of the dome's optical characteristics and the infrared image degradation. The research indicates that the image quality degrades sharply as the vehicle's Mach number increases. Simulations also show that while the thermo-optic effect, elastic-optic effect, thermal deformation, and variation of transmittance have little effect on the optical system, the thermal radiation severely degrades images when vehicles fly at hypersonic speeds. Photo-Optical Instrumentation Engineers

  6. Doming in compressional orogenic settings: New geochronological constraints from the NW Himalaya

    NASA Astrophysics Data System (ADS)

    Robyr, Martin; Hacker, Bradley R.; Mattinson, James M.

    2006-04-01

    In the central and southeastern parts of the Himalayas, the High Himalayan Crystalline (HHC) high-grade rocks are mainly exhumed in the frontal part of the range, as a consequence of a tectonic exhumation controlled by combined thrusting along the Main Central Thrust (MCT) and extension along the South Tibetan Detachment System (STDS). In the NW Himalaya, however, the hanging wall of the MCT in the frontal part of the range consists mainly of low- to medium-grade metasediments (Chamba zone), whereas most of the amphibolite facies to migmatitic gneisses of the HHC of Zanskar are exposed in a more internal part of the orogen as a large-scale dome structure referred to as the Gianbul dome. This Gianbul dome is cored by migmatitic paragneisses formed at peak conditions of 800°C and 8 kbar. This migmatitic core is symmetrically surrounded by rocks of the sillimanite, kyanite ± staurolite, garnet, biotite, and chlorite mineral zones. The structural data from the Miyar-Gianbul Valley section reveal that the Gianbul dome is bounded by two major converging thrust zones, the Miyar Thrust Zone and the Zanskar Thrust Zone, which were reactivated as ductile zones of extension referred to as the Khanjar Shear Zone (KSZ) and the Zanskar Shear Zone (ZSZ), respectively. Geochronological dating of monazites from various migmatites and leucogranite in the core of the Gianbul dome indicates ages between 26.6 and 19.8 Ma. These results likely reflect a high-temperature stage of the exhumation history of the HHC of Zanskar and consequently constrain the onset of extension along both the ZSZ and the KSZ to start shortly before 26.6 Ma. Several recent models interpret that ductile extrusion of the high-grade, low-viscosity migmatites of HHC reflects combined extension along the ZSZ and thrusting along the MCT. Hence our new data constrain the onset of the thrusting along the MCT to start shortly before 26.6 Ma.

  7. Phase competition in trisected superconducting dome

    NASA Astrophysics Data System (ADS)

    Vishik, Inna

    2012-02-01

    The momentum-resolved nature of angle-resolved photoemission spectroscopy (ARPES) has made it a key probe of emergent phases in the cuprates, such as superconductivity and the pseudogap, which have anisotropic momentum-space structure. ARPES can be used to infer the origin of spectral gaps from their distinct phenomenology---temperature, doping, and momentum dependence, and this principle has been used to argue that the pseudogap is a distinct phase from superconductivity, rather than a precursor [1]. We have studied Bi2Sr2CaCu2O8+δ (Bi-2212) using laser-ARPES, and our data give evidence for three distinct quantum phases comprising the superconducting ground state, accompanied by abrupt changes at p˜0.076 and p˜0.19 in the doping-and-temperature dependence of the gaps near the bond-diagonal (nodal) direction [2]. The latter doping likely marks the quantum critical point of the pseudogap, while the former represents a distinct competing phase at the edge of the superconducting dome. Additionally, we find that the pseudogap advances closer towards the node when superconductivity is weak, just below Tc or at low doping, and retreats towards the antinode well below Tc and at higher doping. This phase competition picture together with the two critical doping are synthesized into our proposed phase diagram, which also reconciles conflicting phase diagrams commonly used in the field. Our results underscore the importance of quantum critical phenomena to cuprate superconductivity, provide a microscopic picture of phase competition in momentum space, and predict the existence of phase boundaries inside the superconducting dome which are different from simple extrapolations from outside the dome. [4pt] [1] I. M. Vishik, W. S. Lee, R.-H. He, M. Hashimoto, Z. Hussain, T. P. Devereaux, and Z.-X. Shen. New J. Phys. 12, 105008 (2010). [0pt] [2] I. M. Vishik, M. Hashimoto, R.-H. He, W. S. Lee, F. Schmitt, D. H. Lu, R.G. Moore, C. Zhang, W. Meevasana, T. Sasagawa, S. Uchida, K

  8. Miocene lava flows and domes, cooling fractures, carapace breccia, and avalanche deposits near Goldstone, California

    NASA Astrophysics Data System (ADS)

    Buesch, D.

    2013-12-01

    Mapping and petrography of volcanic rocks in western Fort Irwin (FI), California, provide insights into the cooling history of lava flows and domes and the formation of associated carapace breccia and avalanche deposits. The rocks formed on the eastern margin of the 19-16 Ma Eagle Crags volcanic field (Sabin and others, 1994). Lava compositions range from porphyritic olivine basalt to aphyric rhyolite. Basalt flows are 1-5 m thick and <1-2 km long, and sequences 5-50 m thick are traceable for >7 km. Andesite to rhyolite flows are 30-80 m thick and <1-3 km long, and domes have 100-300 m relief and radial length of 0.6-1.2 km. Cooling fractures, identified by occurrence of margins and geometry, are in all lava flows and domes. Similar to a 'rim' (Buesch and others, 1996 & 1999; Buesch, 2006), a 'margin' is a region along a fracture wall with a finer texture or different type of crystallinity or vesicularity compared to rock inward from the fracture. At FI, margins occur on many fractures and typically are 0.5-3 mm wide. They indicate that a fracture formed during initial cooling, before the bulk of the rock crystallized. Planarity and surface roughness are used to analyze fractures (Buesch and others, 1996). Typically at FI, cooling fractures are planar and smooth, and post-cooling fractures are slightly irregular and slightly rough. Typically, plan views of cooling fractures are 5-6 sided in olivine basalt, and 4-sided in andesite to rhyolite. Fracture sets are mostly perpendicular to the original surface of a flow, and some bend toward the interior. Many lava flows and domes have lateral and capping breccias referred to as carapace breccia. Similar breccia also cloaks individual lobes of composite domes. Carapace breccia can grade down into a non-brecciated interior, but in some cases, compositionally similar late-stage flow-banded lava was injected beneath the breccia, Breccia fragments are vitric or crystallized, and many have margins that do not match those of

  9. The Discovery Dome: A Tool for Increasing Student Engagement

    NASA Astrophysics Data System (ADS)

    Brevik, Corinne

    2015-04-01

    The Discovery Dome is a portable full-dome theater that plays professionally-created science films. Developed by the Houston Museum of Natural Science and Rice University, this inflatable planetarium offers a state-of-the-art visual learning experience that can address many different fields of science for any grade level. It surrounds students with roaring dinosaurs, fascinating planets, and explosive storms - all immersive, engaging, and realistic. Dickinson State University has chosen to utilize its Discovery Dome to address Earth Science education at two levels. University courses across the science disciplines can use the Discovery Dome as part of their curriculum. The digital shows immerse the students in various topics ranging from astronomy to geology to weather and climate. The dome has proven to be a valuable tool for introducing new material to students as well as for reinforcing concepts previously covered in lectures or laboratory settings. The Discovery Dome also serves as an amazing science public-outreach tool. University students are trained to run the dome, and they travel with it to schools and libraries around the region. During the 2013-14 school year, our Discovery Dome visited over 30 locations. Many of the schools visited are in rural settings which offer students few opportunities to experience state-of-the-art science technology. The school kids are extremely excited when the Discovery Dome visits their community, and they will talk about the experience for many weeks. Traveling with the dome is also very valuable for the university students who get involved in the program. They become very familiar with the science content, and they gain experience working with teachers as well as the general public. They get to share their love of science, and they get to help inspire a new generation of scientists.

  10. Transdomes: Emplacement of Migmatite Domes in Oblique Tectonic Settings

    NASA Astrophysics Data System (ADS)

    Teyssier, C. P.; Rey, P. F.; Whitney, D. L.; Mondy, L. S.; Roger, F.

    2014-12-01

    Many migmatite domes are emplaced within wrench corridors in which a combination of strike-slip and extensional detachment zones (pull-apart, extensional relay, or transfer zones) focus deep-crust exhumation. The Montagne Noire dome (France, Variscan Massif Central) exemplifies wrench-related dome formation and displays the following structural, metamorphic, and geochronologic characteristics of a 'transdome': the dome is elongate in the direction of extension; foliation outlines a double dome separated by a high-strain zone; lineation is shallowly plunging with a fairly uniform trend that parallels the strike of the high-strain zone; subdomes contain recumbent structures overprinted by upright folds that affected upward by flat shear zones associated with detachment tectonics; domes display a large syn-deformation metamorphic gradient from core (upper amphibolite facies migmatite) to margin (down to greenschist facies mylonite); some rocks in the dome core experienced isothermal decompression revealed by disequilibrium reaction textures, particularly in mafic rocks (including eclogite); and results of U-Pb geochrononology indicate a narrow range of metamorphic crystallization from core to mantling schist spanning ~10 Myr. 3D numerical modeling of transdomes show that the dome solicits a larger source region of partially molten lower crust compared to 2D models; this flowing crust creates a double-dome architecture as in 2D models but there are differences in the predicted thermal history and flow paths. In a transtension setting, flow lines converge at depth (radial-centripetal flow) toward the zone of extension and diverge at shallow levels in a more uniform direction that is imposed by upper crust motion and deformation. This evolution produces a characteristic pattern of strain history, progressive fabric overprint, and P-T paths that are comparable to observed dome rocks.

  11. Geologic study of Kettle dome, northeast Washington. Final report

    SciTech Connect

    Not Available

    1980-10-01

    This geologic study of Kettle dome, northeast Washington, encompasses an area of approximately 800 square miles (2048 sq km). The evaluation of uranium occurrences associated with the igneous and metamorphic rocks of the dome and the determination of the relationship between uranium mineralization and stratigraphic, structural, and metamorphic features of the dome are the principal objectives. Evaluation of the validity of a gneiss dome model is a specific objective. The principal sources of data are detailed geologic mapping, surface radiometric surveys, and chemical analyses of rock samples. Uranium mineralization is directly related to the presence of pegmatite dikes and sills in biotite gneiss and amphibolite. Other characteristics of the uranium occurrences include the associated migmatization and high-grade metamorphism of wallrock adjacent to the pegmatite and the abrupt decrease in uranium mineralization at the pegmatite-gneiss contact. Subtle chemical characteristics found in mineralized pegmatites include: (1) U increase as K/sub 2/O increases, (2) U decreases as Na/sub 2/O increases, and (3) U increases as CaO increases at CaO values above 3.8%. The concentration of uranium occurrences in biotite gneiss and amphibolite units results from the preferential intrusion of pegmitites into these well-foliated rocks. Structural zones of weakness along dome margins permit intrusive and migmatitic activity to affect higher structural levels of the dome complex. As a result, uranium mineralization is localized along dome margins. The uranium occurrences in the Kettle dome area are classified as pegmatitic. Sufficient geologic similarities exist between Kettle dome and the Rossing uranium deposit to propose the existence of economic uranium targets within Kettle dome.

  12. Spatial and temporal patterns of dome extrusion during the 2004-2008 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Salzer, J. T.; Denlinger, R. P.; Diefenbach, A. K.; Walter, T. R.

    2014-12-01

    Extensive efforts by the USGS Cascades Volcano Observatory in response to the 2004-2008 dome building eruption at Mount St. Helens recorded the extrusion of seven dacite spines. Efforts included a network of time-lapse cameras. Published studies of decimated data from these cameras show strong correlations between (long-term) extrusion velocities determined from the camera imagery and ancillary geophysical data, such as dome tilt and RSAM seismicity. However, more detailed analysis of these data should provide better constraints on physical processes behind dome extrusion. Here we apply modern computer vision techniques to explore the spatiotemporal variability and interactions occurring during spine extrusion and dome growth. Digital Image Correlation (DIC) delineates the deformation field in a series of images at sub-pixel level, and quantifies dome, talus and glacier deformation at unprecedented resolution, revealing spatiotemporal variability of the strain field on the time scale of hours. We identify sharp boundaries between the vertically extruding spine, laterally displaced material, and downward-creeping talus. The spine growth at Mount St. Helens appears locally constrained and structurally separated into distinct segments. The velocities of different dome segments are generally correlated, but displacement patterns of the talus are more complex. We identify short term fluctuations with periods of hours to days superimposed on longer term fluctuations having periods of several weeks. The short term episodes of high displacement rates are often associated with strongly degassing plumes observed in the camera imagery. Over longer periods (days to weeks), extrusion rates form a sinusoidal fluctuating pattern, marked by sharp increases and gradual decreases in velocity. These observations substantiate the correlations with seismic and geodetic data shown in previous studies, but more closely constrain the velocity fluctuations of each spine. These fluctuations

  13. Geology and development history of Jennings salt dome 1901-1985: clue to future of Gulf Coast salt domes

    SciTech Connect

    Cook, J.C.; Harrison, F.W. Jr.

    1986-05-01

    Historically, salt domes have been the primary target of oil and gas exploration in the Texas and Louisiana Gulf Coast. In south Louisiana, the 89 piercement salt dome fields discovered since 1901 have produced 6,492,462,685 bbl of oil and condensate, representing approximately 60% of all oil and condensate produced in south Louisiana. Because of the tremendous volume of oil already extracted, there may be doubt about finding significant reserves on these features in the future. A current review of Jennings salt dome, the first Louisiana oil field, however, suggests that south Louisiana piercement domes still have large undiscovered reserves. Jennings dome, which has produced continuously since its discovery in 1901, has produced, as of 1985, 115 million bbl of oil and condensate. Its long and active exploration history is representative of many piercement domes in south Louisiana. A combination of characteristics explain why Jennings, as well as other domes, continues to be the focus of major exploration efforts. Piercement salt domes are generally complex both stratigraphically and structurally because of their geologic origin. Prolific high-angle faulting coupled with depositional unconformities and rapid stratigraphic changes make it difficult to determine accurately the precise nature and extent of existing hydrocarbon traps. Additional, the occurrence of multiple sand reservoirs and outstanding recovery rates of oil in place result in areally small reservoirs that contain substantial reserves.

  14. The Lifferth Dome for Small Telescopes

    NASA Astrophysics Data System (ADS)

    Wilson, B. L.; Olsen, C. S.; Iverson, E. P.; Paget, A.; Lifferth, W.; Brown, P. J.; Moody, J. W.

    2004-12-01

    The Lifferth Dome is a pull-off roof designed for small telescopes and other observational equipment. It was specifically designed for the needs of the ROVOR project. The roof itself is completely removed from the observatory housing walls and cranked off to the side below the optical horizon. This is done using two swing arms on either side of the observatory that work in unison to lift the roof off the structure and rotate down and away into a cleared location. The torque is provided by a threaded rod connected to an electric motor at the back of the building. As the motor rotates, the threads turn through a threaded sleeve connected directly to the support arms. Advantages to this design are no lost horizon, no roller surfaces to keep clean, low power and simple limit switches. Operation is by computer control using by National Instruments LabVIEW via the internet. We present its design and construction.

  15. Centrifugally-spun carbon microfibers and porous carbon microfibers as anode materials for sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Dirican, Mahmut; Zhang, Xiangwu

    2016-09-01

    Natural abundance and low cost of sodium resources bring forward the sodium-ion batteries as a promising alternative to widely-used lithium-ion batteries. However, insufficient energy density and low cycling stability of current sodium-ion batteries hinder their practical use for next-generation smart power grid and stationary storage applications. Electrospun carbon microfibers have recently been introduced as a high-performance anode material for sodium-ion batteries. However, electrospinning is not feasible for mass production of carbon microfibers due to its complex processing condition, low production rate and high cost. Herein, we report centrifugal spinning, a high-rate and low-cost microfiber production method, as an alternative approach to electrospinning for carbon microfiber production and introduce centrifugally-spun carbon microfibers (CMFs) and porous carbon microfibers (PCMFs) as anode materials for sodium-ion batteries. Electrochemical performance results indicated that the highly porous nature of centrifugally-spun PCMFs led to increased Na+ storage capacity and improved cycling stability. The reversible capacity of centrifugally-spun PCMF anodes at the 200th cycle was 242 mAh g-1, which was much higher than that of centrifugally-spun CMFs (143 mAh g-1). The capacity retention and coulombic efficiency of the centrifugally-spun PCMF anodes were 89.0% and 99.9%, respectively, even at the 200th cycle.

  16. The eastern Central Pamir Gneiss Domes: temporal and spatial geometry of burial and exhumation

    NASA Astrophysics Data System (ADS)

    Rutte, Daniel; Stearns, Michael; Ratschbacher, Lothar

    2013-04-01

    of the domes are Paleozoic. Detrital zircon data from the low-grade cover and surrounding units of the Muskol dome suggest that low-grade cover and high-grade dome formed from the same Paleozoic, possibly early Mesozoic strata. This indicates that the upper crust of the Central Pamir thickened to at least 30 km in phase (1). Based on our data and those of Robinson et al. (2012) underthrusted Karakul-Mazar (Songpan-Ganze) material (as discussed by Schwab et al. 2004), in analogy to the Tibetan Qiangtang domes (Kapp et al. 2000), can be ruled out as protolith for the Muskol and Shatput domes. (3) Neogene shortening is bi-vergent: top-to-S back-thrusting north of the Central Pamir Gneiss Domes opposes top-to-N thrusting in the south. Neogene deformation affected ~18 Ma (Ar-Ar) coarse fluvial and alluvial fan strata with basaltic dikes and flows south of the dome; restoration of these strata yielded up to 40% shortening. Total shortening by thrusting of the Central Pamir is at least 40% in the Shatput-Muskol area with a minimal total shortening of 70 km; internal deformation with recumbent north-verging folds within the domes and its cover indicate much higher values. Literature: Kapp, P., Yin, A., Manning, C. E., Murphy, M., Harrison, T. M., Spurlin, M., Lin, D., Yi-Guang, D., Cun-Ming, W. (2000) Blueshist-bearing metamorphic core complexes in the Qiangtang block reveal deep crustal structure of northern Tibet, Geology, v. 28; no. 1; p.19-22 Robinson, A. C., M. Ducea, and T. J. Lapen (2012), Detrital zircon and isotopic constraints on the crustal architecture and tectonic evolution of the northeastern Pamir, Tectonics, 31, TC2016, doi:10.1029/2011TC003013. Schwab, M., Ratschbacher, L., Siebel, W., McWilliams, M., Minaev, V., Lutkov., V., Chen, F., Stanek, K., Nelson, B. and Wooden, J. L. (2004) Assembly of the Pamir: Age and origin of magmatic belts from the southern Tien Shan to the southern Pamir and their relation to Tibet, Tectonics, 23, No. 4, TC4002

  17. Tensile strength of dome rocks and lavas at Santiaguito dome complex, Guatemala

    NASA Astrophysics Data System (ADS)

    Hornby, Adrian; Lamb, Oliver; Lamur, Anthony; Lavallée, Yan

    2015-04-01

    Lava domes are inherently unstable structures, subject to intense gas flux and rapid variations in the state of stress. At shallow depths confining stresses are minimal and deformation is dilatant, occurring predominantly through tensile fractures. This fracture mode facilitates outgassing and contributes to the development of gas-and-ash activity as well as vulcanian eruptions. However, there is a paucity of tensile strength data for volcanic materials in the published literature, and we know of no paper which addresses this at high temperatures. We study the tensile strength of dome rocks collected at the Santiaguito dome complex, Guatemala, over a porosity range of 3-25%. Indirect tensile (Brazilian) tests were conducted on 40-mm diameter cores, by imposing a compressive displacement rate (radial to the core) of 4 micron/s at room temperature as well as an eruptive temperature of ca. 850 °C. An acoustic monitoring system is employed to track the nucleation, propagation and coalescence of fractures leading to complete sample failure. We find that the rocks' tensile strength exhibits a nonlinear decrease with porosity. Preliminary tests at high temperature indicate that some rocks exhibit a higher tensile strength (than at room temperature); in these experiments, samples containing a higher fraction of interstitial melt revealed an additional component of viscous flow. Further experiments conducted at higher strain rates will define the brittle response of the liquid during tensile failure. The data is compared against similar datasets for volcanic rocks. We will discuss implications for shallow volcanic processes ranging from dilation bands and tuffisite formation to gas-and-ash explosions and dome structural stability.

  18. Blowing off steam: Tuffisite formation as a regulator for lava dome eruptions

    NASA Astrophysics Data System (ADS)

    Kendrick, Jackie; Lavallée, Yan; Varley, Nick; Wadsworth, Fabian; Lamb, Oliver; Vasseur, Jérémie

    2016-04-01

    Tuffisites are veins of variably sintered, pyroclastic particles that form in conduits and lava domes as a result of localized fragmentation events during gas-and-ash explosions. Those observed in-situ on the active 2012 lava dome of Volcán de Colima range from voids with intra-clasts showing little movement and interpreted to be failure-nuclei, to sub-parallel lenses of sintered granular aggregate interpreted as fragmentation horizons, through to infilled fractures with evidence of viscous remobilization. All tuffisites show evidence of sintering. Further examination of the complex fracture-and-channel patterns reveals viscous backfill by surrounding magma, suggesting that lava fragmentation was followed by stress relaxation and continued viscous deformation as the tuffisites formed. The natural tuffisites are more permeable than the host andesite, and have a wide range of porosity and permeability compared to a narrower window for the host rock, and gauging from their significant distribution across the dome, we posit that the tuffisite veins may act as important outgassing pathways. To investigate tuffisite formation we crushed and sieved andesite from the lava dome and sintered it at magmatic temperatures for different times. We then assessed the healing and sealing ability by measuring porosity and permeability, showing that sintering reduces both over time. During sintering the porosity-permeability reduction occurs due to the formation of viscous necks between adjacent grains, a process described by the neck-formation model of Frenkel (1945). This process leads the granular starting material to a porosity-permeability regime anticipated for effusive lavas, and which describes the natural host lava as well as the most impervious of natural tuffisites. This suggests that tuffisite formation at Volcán de Colima constructed a permeable network that enabled gas to bleed passively from the magma. We postulate that this progressively reduced the lava dome

  19. Geohydrology of the Keechi, Mount Sylvan, Oakwood, and Palestine salt domes in the northeast Texas salt-dome basin

    USGS Publications Warehouse

    Carr, Jerry E.; Halasz, Stephen J.; Peters, Henry B.

    1980-01-01

    Additional problems concerning the hydrologic stability of Oakwood and Palestine Salt Domes have resulted from the disposal of oil-field salinewater in the cap rock at the Oakwood Dome and previous solution mining of salt at the Palestine Dome Additional investigations are needed to determine if a selected dome is hydrologically stable. Needed investigations include: (1) A more complete comparative analysis of the regional and local geohydrologic system; (2) a site-specific drilling and sampling program to analyze the cap rock-aquifer boundary, sediment distribution, hydraulic-parameter variations, hydraulic-head relationships, and hydrochemical patterns; and (3) mass-transport computer modeling of ground-water flow at the domes.

  20. Structural review of the Vredefort dome

    NASA Technical Reports Server (NTRS)

    Colliston, W. P.; Reimold, W. U.

    1992-01-01

    The structure of the older-than-3.2-Ga Archean basement and Archean-to-Precambrian sedimentary/volcanic rocks (3.07 to ca. 2.2 Ga) in the center of the Witwatersrand Basin to the southwest of Johannesburg (South Africa) is dominated by the ca. 2.0-Ga megascopic Vredefort 'Dome' structure. The effect of the 'Vredefort event' is demonstrably large and is evident within a northerly arc of about 100 km radius around the granitic core of the structure. Northerly asymmetric overturning of the strata is observed within the first 17 km (strata is horizontal in the south), followed by a 40-km-wide rim synclinorium. Fold and fault structures (normal, reverse, and strike-slip) are locally as well as regionally concentrically arranged with respect to the northern and western sides of the structure. The unusual category of brittle deformation, the so-called 'shock deformation', observed in the collar strata has attracted worldwide attention over the past two decades. These deformation phenomena include the presence of coesite and stishovite, mylonites, and pseudotachylites, cataclasis at a microscopic scale, and the ubiquitous development of multiply striated joint surfaces (which include shatter cones, orthogonal, curviplanar, and conjugate fractures). The macroscopic to microscopic deformation features have led to the formulation of various hypotheses to account for the origin of the Vredefort structure: (1) tectonic hypotheses--deep crustal shear model, doming and N-directed thrust fault model, fold interference model, and diapir model; (2) the exogenous bolide impact hypothesis; and (3) the endogenous cryptoexplosion model.

  1. The Vaasa migmatitic complex: the birth, growth and death of a thermal dome

    NASA Astrophysics Data System (ADS)

    Chopin, Francis; Korja, Annakaisa; Hölttä, Pentti; Eklund, Olav; Tapani Rämö, Osmo

    2015-04-01

    The Vaasa migmatitic complex, or Vaasa dome, is cored by diatexite migmatites and S-type granitoids and gradually mantled by metatexite migmatites and mica schist with thin metabasite-andesite intercalations. Previous geochemical studies have demonstrated that the metasediments are the sources of the melted core: it have been suggested that the complex have been formed by in-situ melting of a basin. Field work studies highlight the formation of a gently dipping metamorphic fabric with a lateral increase of the in-situ melt content towards the core of the dome (D1). This early layered and partially melted fabric is then affected by a regional N-S shortening forming km- to outcrop-scale E-W striking folds and new sub-vertical foliation (D2). Late sub-vertical shearing is visible along the dome border and within the diatexitic zone (D3). No late detachment structures have been observed. In the metamorphic belt, the grade increases from medium-T amphibolite facies to low-P granulite facies towards the core of the dome. Pseudosections in the MnNCKFMASHTO system have been performed in one mica schist (Grt+BtPl+Qz±Std+Sill+And) and one metatexite migmatite (Bt+Liq+Crd+Pl+Kfs+Grt+Qz±Sill+And). The metamorphic peaks are bracketed at 560°C at 5 kbar and 750-770°C at 4.5-5 kbar, respectively. The retrograde condition is situated at 540°C and <3 kbar for both lithologies. This implies an isobaric increase of the metamorphic grade towards the core of the dome. An isothermal decompression for the schist and a retrograde PT path for the migmatites are observed. Existing and new U/Pb monazite ages from mica schists, migmatites and clustered at 1860-1865 Ma whereas U/Pb ages from metamorphic and magmatic zircons are older and clustered at 1875 Ma. The latter might represent the peak of melting process and associated metamorphism whereas monazites ages might be related to the cooling of the orogenic middle crust. It has to be noticed that few monazites from metamorphic rocks of

  2. THEMIS Observations of Domes and Associated Lineaments in Arcadia Planitia

    NASA Astrophysics Data System (ADS)

    Milam, K. A.; McSween, H. Y.

    2003-12-01

    The northern plains of Mars contain several high concentrations (Acidalia, Utopia, Elysium, etc.) of small (<10 km diameter) domes, proposed to be volcanic. Recent data sets from the Mars Global Surveyor and Mars Odyssey spacecraft provide new insight into the formation of domes in Arcadia Planitia. Daytime and nighttime thermal infrared (TIR) data from the Thermal Emission Imaging System (THEMIS), visible images from THEMIS and the Mars Orbiter Camera, and elevation data from the Mars Orbiter Laser Altimeter were used to study a 390,000 km 2 area ˜1500 km to the northwest of Elysium Mons. Of interest is a region centered on Tyndall crater and bordered by Phlegras Montes to the west. The area is characterized by gentle, westward-sloping plains, with noticeable slope breaks along several N-S trending wrinkle ridges. Several hundred circular domes dot this area. Domes display features consistent with a volcanic origin. Most are circular to slightly elliptical at their base, with basal diameters ranging from 0.5-6 km. Summits typically rise <300 m above the surrounding plains. Domes have shallow slopes (lacking significant slope breaks) that range from 1-9° . Visible images and TIR-derived temperature data suggest that slopes are composed of finer-grained material (as compared to the coarser-grained summits). Less than 25% of domes appear to have summit depressions and ~ 1% show fractured summit areas. Some domes appear to be randomly distributed, but many are aligned in chains according to wrinkle ridge orientations. Using THEMIS data, we have detected over 165 domes that are aligned with and superimposed upon over 145 lineaments. Most lineaments are <500 m in width and range from 1-66 km in length. Many lineaments do follow N-S trends similar to those of wrinkle ridges, although other orientations are common. Several lineaments can be seen as open fractures, while others appear to be filled with fine-grained sediment. While most domes are superimposed upon

  3. The giant Shakhdara migmatitic gneiss dome, Pamir, India-Asia collision zone: 2. Timing of dome formation

    NASA Astrophysics Data System (ADS)

    Stübner, Konstanze; Ratschbacher, Lothar; Weise, Carsten; Chow, Judy; Hofmann, Jakob; Khan, Jahanzeb; Rutte, Daniel; Sperner, Blanka; Pfänder, Jörg A.; Hacker, Bradley R.; Dunkl, István.; Tichomirowa, Marion; Stearns, M. A.

    2013-09-01

    Cenozoic gneiss domes—exposing middle-lower crustal rocks—cover ~30% of the surface exposure of the Pamir, western India-Asia collision zone; they allow an unparalleled view into the deep crust of the Asian plate. We use titanite, monazite, and zircon U/Th-Pb, mica Rb-Sr and 40Ar/39Ar, zircon and apatite fission track, and zircon (U-Th)/He ages to constrain the exhumation history of the ~350 × 90 km Shakhdara-Alichur dome, southwestern Pamir. Doming started at 21-20 Ma along the Gunt top-to-N normal-shear zone of the northern Shakhdara dome. The bulk of the exhumation occurred by ~NNW-ward extrusion of the footwall of the crustal-scale South Pamir normal-shear zone along the southern Shakhdara dome boundary. Footwall extrusion was active from ~18-15 Ma to ~2 Ma at ~10 mm/yr slip and with vertical exhumation rates of 1-3 mm/yr; it resulted in up to 90 km ~N-S extension, coeval with ~N-S convergence between India and Asia. Erosion rates were 0.3-0.5 mm/yr within the domes and 0.1-0.3 mm/yr in the horst separating the Shakhdara and Alichur domes and in the southeastern Pamir plateau; rates were highest along the dome axis in the southern part of the Shakhdara dome. Incision along the major drainages was up to 1.0 mm/yr. Thermal modeling suggests geothermal gradients as high as 60°C/km along the trace of the South Pamir shear zone and their strong N-S variation across the dome; the gradients relaxed to ≤40-45°C/km since the end of doming.

  4. Experimental study of the mutual influence of fibre Faraday elements in a spun-fibre interferometer

    SciTech Connect

    Gubin, V P; Morshnev, S K; Przhiyalkovsky, Ya V; Starostin, N I; Sazonov, A I

    2015-08-31

    An all-spun-fibre linear reflective interferometer with two linked Faraday fibre coils is studied. It is found experimentally that there is mutual influence of Faraday fibre coils in this interferometer. It manifests itself as an additional phase shift of the interferometer response, which depends on the circular birefringence induced by the Faraday effect in both coils. In addition, the interferometer contrast and magneto-optical sensitivity of one of the coils change. A probable physical mechanism of the discovered effect is the distributed coupling of orthogonal polarised waves in the fibre medium, which is caused by fibre bend in the coil. (interferometry)

  5. Primary arm spacing in chill block melt spun Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Glasgow, T. K.

    1987-01-01

    Chill block melt spun ribbons of Ni-Mo binary alloys containing 8.0 to 41.8 wt pct Mo have been prepared under carefully controlled processing conditions. The growth velocity has been determined as a function of distance from the quench surface from the observed ribbon thickness dependence on the melt puddle residence time. Primary arm spacing measured at the midribbon thickness locations show a dependence on growth velocity and alloy composition which is expected from dendritic growth models for binary alloys directionally solidified in a positive temperature gradient.

  6. Primary arm spacing in chill block melt spun Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Glasgow, T. K.

    1986-01-01

    Chill block melt spun ribbons of Ni-Mo binary alloys containing 8.0 to 41.8 wt % Mo have been prepared under carefully controlled processing conditions. The growth velocity has been determined as a function of distance from the quench surface from the observed ribbon thickness dependence on the melt puddle residence time. Primary arm spacings measured at the midribbon thickness locations show a dependence on growth velocity and alloy composition which is expected from dendritic growth models for binary alloys directionally solidified in a positive temperature gradient.

  7. Diagenesis of the Carrizo sandstone at Bulter salt dome, East Texas Basin: Implications for paleofluid-flow

    SciTech Connect

    Smith, J.S.

    1996-09-01

    The calcite- and pyrite-cemented Eocene Carrizo sandstone on the flank of Butler salt dome in East Texas was formed by processes similar to those that form calcite cap rocks throughout the Gulf Coast. Isotopic evidence indicates that the bacterial degradation of hydrocarbons combined with the venting of deep sour gas and the dissolution of anhydrite from the dome resulted in the precipitation of these cements. Identification of the origins of these cements has lead to a better understanding of the paleofluid-flow associated with the dome. The Carrizo is a diagenetic quartzarenite with 42-50% concretionary calcite and pyrite cements. The calcite cement is bound to the northwest by a pyrite-cemented normal fault radial to the dome while the pyrite is found on both sides of the fault. Calcite {delta}{sup 13}C (-18 to -37 {per_thousand} (PDB)) and {delta}{sup 18}O (-6 to -9{per_thousand} (PDB)) show a mixed source of both waters (meteoric and deep) and hydrocarbons (oil, gas, and lignite). Heavy pyrite {delta}{sup 34}S (12-15 {per_thousand} (CDI)) represents H{sub 2}S supply from deep sour gas. Deep waters, methane, and H{sub 2}S migrated up the dome flank and out the fault into the Carrizo, already containing oil and lignite, and pyrite precipitated along the fault and in adjacent sediments. Bacteria oxidized the hydrocarbons and, with the meteoric and formation waters, formed bicarbonate. Calcium bearing fluids from the dome moved into the Caffizo, and calcite began to precipitate. However, pyrite cement along the fault prevented northwestern migration of the fluids, confining calcite precipitation to the southeast.

  8. Fabrication of micro-convex domes using long pulse laser

    NASA Astrophysics Data System (ADS)

    Wang, Xingsheng; Zhang, Yongnian; Wang, Ling; Xian, Jieyu; Jin, Meifu; Kang, Min

    2017-01-01

    Micro-convex domes inspired from nature can be machined by chemical and physical routes to achieve specific functions. Laser surface texturing (LST) is the front runner among the current material micro-processing technologies. However, most of the studies relating to LST dealt with the formation of micro-dimples. In this paper, LST using long pulse laser was used to create micro-convex domes on 304L stainless steel. Spherical-cap-shaped domes with diameters of 30-75 μm and height of 0.9-5.5 μm were created through LST. The effects of laser-processing parameters on surface morphologies of the created convex domes were investigated. The height of the convex dome increased at first and then decreased with the increasing laser power. The change tendency of the height with the pulse duration varied at different laser powers. The diameter of the convex dome increased almost linearly with the laser power or pulse duration. The superior micro-convex domes were achieved at a pulse energy of 5.6 mJ with a laser power of 80 W and pulse duration of 70 μs.

  9. Lava Dome Growth at Volcan de Fuego MEXICO (Colima Volcano), October 2001 to May 2002

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Nunez-Cornu, F. J.; Reyes-Davila, G. A.

    2002-12-01

    The Volcan de Fuego (19.512 N, 103.617 W) is located on the border between the States of Jalisco and Colima, Mexico, it is also known as Colima Volcano or Zapotl n Volcano, is a stratovolcano rising nearly 4000 m above sea level, and is the most active volcano in Mexico. Recent activity has been characterized by at least 3 different phases since January 1998 when seismic swarms began and ended with the extrusion of blocky lava in November 22, 1998 by the West vent as the 1991 eruptive process. That extrusive period lasted until the end of January, 1999 when was possible to observe a change in the seismic pattern, which mark the beginning of a new eruptive regime, an explosive one. On February 10, 1999 at approximately 0154 local time, 0754 gmt, an explosive event happens at the summit dome of Volc n de Fuego, four more big explosions took place at the summit the last one at dawn February 22, 2001. These explosions opened a new crater at the summit with a elliptical form with radius of 260 x 225 m and depth between 40 m and 15 m. A small dome structure inside the new crater was reported by March 2001. A reconnaissance flight in August 2001 shows two main features in the main crater an steep-sided mound(scoria cone) over the West vent and an inner crater on the NE vent. On October 31 Civil Defense members at Nevado Base on Nevado de Colima observed a neddle over the main crater rim, reconnaissance flight shows a spiny, 40 m high with a diameter of 20 m grows from the NE vent, the spiny seems to formed by material of the 1976 eruption. Continuous aerial observations allow us to follow the growth of a new dome pushing out the spiny. On November 23 the dimensions of the dome under the spiny were a radius of about 14 m and 21 m high for a total extrusion of 86,000 m3 which implies a extrusion rate of 0.027m3 /seg. By December the dome push out the spiny and began to grow from the NW vent. By December 29 an increase in the rate of extrusion was observed reaching a value

  10. Maximum potential erosion and inundation of seven interior salt domes

    SciTech Connect

    Aronow, S.

    1982-08-01

    Seven interior salt domes have been evaluated in regard to erosion or inundation due to natural events. The most likely possibility of either event occurring would be associated with continental glaciation. The domes were evaluated based on maximum previous sea level changes due to glaciation and effects caused by melting of existing ice sheets. Results are listed for each of the seven domes. Past history indicates a likelihood of returning to a glacial period. The subsequent fall of sea level may cause regrading of streams in the area. A conservative evaluation of this phenomenon was performed and the results are reported.

  11. On the Performance of Pyrgeometers with Silicon Domes.

    NASA Astrophysics Data System (ADS)

    Weiss, A.

    1981-08-01

    Net radiation and the individual components of incoming and outgoing solar and longwave radiation were measured over alfalfa (Medicago sativa. L.). Solar radiation was measured with precision spectral pyranometers and longwave radiation with pyrgeometers fitted with silicon rather than KRS-5 domes. Direct measurement of incoming longwave irradiance was compared with the value calculated as the residual of the terms comprising net radiation. Shading the pyrgeometer indicated heating of the dome and under calm, sunny conditions, errors as large as 98 W m2 were observed. Visual inspection of the dome indicated no deterioration.

  12. The Effects of the Foldable Dome of KDUST on the Observation Based on CFD Method at Dome A

    NASA Astrophysics Data System (ADS)

    Xu, Jianghai; Gong, Xuefei; Gu, Bozhong

    2016-12-01

    For modern telescopes with the strict requirement of high-resolution image quality, the influence of wind load cannot be ignored. KDUST is a 2.5 m optical telescope and will be installed at Dome A. To study the effects of wind load on KDUST, the low-frequency wind speed data observed by KL-AWS-2G weather station at Dome A are transformed into high frequency based on the theory of wind speed fluctuation spectrum; then, the numerical wind tunnel simulation is conducted under the conditions of different dominant wind directions, different dome opening angles, and the elevation angles of KDUST. The results show that different wind directions mainly affect the wind velocity and turbulence kinetic energy around the telescope; the optical path difference increases along with the increase of the dome opening angle, but decreases with the increase of the elevation angle of KDUST; the dome seeing decreases with the increase of both the dome opening angle and elevation angle. This simulation will provide a useful reference for the future design and construction of KDUST and its foldable dome.

  13. Holocene block-and-ash flows from summit dome activity of Citlaltépetl volcano, Eastern Mexico

    NASA Astrophysics Data System (ADS)

    Carrasco-Núñez, Gerardo

    1999-01-01

    A major eruption produced several block-and-ash flows about 4,100 years B.P. at Citlaltépetl volcano (Pico de Orizaba), an ice-capped, 5670-m-high, andesitic, active stratovolcano located at the eastern end of the Mexican Volcanic Belt. Repetitive gravitational collapse of a dacitic dome at the summit crater produced a series of block-and-ash flows, lahars, and floods, which were channeled through two main river-valleys on the west and south flanks of the volcano. The total erupted volume is estimated to be at least 0.27 km 3. The deposits in both areas are similar in composition, and size, but they differ in the area covered, distribution, and structure. The western deposits form a large fan, cover a larger area, and include numerous laharic and fluviatile deposits. In contrast, the southern deposits form prominent terraces where confined in narrow channels, and have associated laharic units in distal areas, where the flows reach a maximum distance of 30 km from the vent. Directed disruptions of a central summit dome occurred, possibly first to the west and then to the southeast, perhaps due to minor modifications of the summit dome morphology, producing the voluminous block-and-ash flow deposits documented here. The flows were strongly controlled by topography, influencing the deposition of the moving particles. Grain-size variations along the flow paths are hardly detectable suggesting no evident lateral downstream transformations. Because sudden changes in dome morphology may cause significant variations in the direction of future dome collapse, specific areas of potential affectation cannot be predicted. Therefore, about 350,000 inhabitants living within a radius of 35-km from the vent could be potentially impacted if catastrophic block-and-ash flows were to recur in the future from similar summit dome activity. Recognition of these deposits is therefore important for hazard assessment because some seemingly safe areas may be at high risk.

  14. Strength and Water Interactions of Cellulose I Filaments Wet-Spun from Cellulose Nanofibril Hydrogels

    PubMed Central

    Lundahl, Meri J.; Cunha, A. Gisela; Rojo, Ester; Papageorgiou, Anastassios C.; Rautkari, Lauri; Arboleda, Julio C.; Rojas, Orlando J.

    2016-01-01

    Hydrogels comprising cellulose nanofibrils (CNF) were used in the synthesis of continuous filaments via wet-spinning. Hydrogel viscosity and spinnability, as well as orientation and strength of the spun filaments, were found to be strongly affected by the osmotic pressure as determined by CNF surface charge and solid fraction in the spinning dope. The tensile strength, Young’s modulus and degree of orientation (wide-angle X-ray scattering, WAXS) of filaments produced without drawing were 297 MPa, 21 GPa and 83%, respectively, which are remarkable values. A thorough investigation of the interactions with water using dynamic vapour sorption (DVS) experiments revealed the role of sorption sites in the stability of the filaments in wet conditions. DVS analysis during cycles of relative humidity (RH) between 0 and 95% revealed major differences in water uptake by the filaments spun from hydrogels of different charge density (CNF and TEMPO-oxidised CNF). It is concluded that the mechanical performance of filaments in the presence of water deteriorates drastically by the same factors that facilitate fibril alignment and, consequently, enhance dry strength. For the most oriented filaments, the maximum water vapour sorption at 95% RH was 39% based on dry weight. PMID:27465828

  15. Strength and Water Interactions of Cellulose I Filaments Wet-Spun from Cellulose Nanofibril Hydrogels

    NASA Astrophysics Data System (ADS)

    Lundahl, Meri J.; Cunha, A. Gisela; Rojo, Ester; Papageorgiou, Anastassios C.; Rautkari, Lauri; Arboleda, Julio C.; Rojas, Orlando J.

    2016-07-01

    Hydrogels comprising cellulose nanofibrils (CNF) were used in the synthesis of continuous filaments via wet-spinning. Hydrogel viscosity and spinnability, as well as orientation and strength of the spun filaments, were found to be strongly affected by the osmotic pressure as determined by CNF surface charge and solid fraction in the spinning dope. The tensile strength, Young’s modulus and degree of orientation (wide-angle X-ray scattering, WAXS) of filaments produced without drawing were 297 MPa, 21 GPa and 83%, respectively, which are remarkable values. A thorough investigation of the interactions with water using dynamic vapour sorption (DVS) experiments revealed the role of sorption sites in the stability of the filaments in wet conditions. DVS analysis during cycles of relative humidity (RH) between 0 and 95% revealed major differences in water uptake by the filaments spun from hydrogels of different charge density (CNF and TEMPO-oxidised CNF). It is concluded that the mechanical performance of filaments in the presence of water deteriorates drastically by the same factors that facilitate fibril alignment and, consequently, enhance dry strength. For the most oriented filaments, the maximum water vapour sorption at 95% RH was 39% based on dry weight.

  16. The anisotropic mechanical behaviour of electro-spun biodegradable polymer scaffolds: Experimental characterisation and constitutive formulation.

    PubMed

    Limbert, Georges; Omar, Rodaina; Krynauw, Hugo; Bezuidenhout, Deon; Franz, Thomas

    2016-01-01

    Electro-spun biodegradable polymer fibrous structures exhibit anisotropic mechanical properties dependent on the degree of fibre alignment. Degradation and mechanical anisotropy need to be captured in a constitutive formulation when computational modelling is used in the development and design optimisation of such scaffolds. Biodegradable polyester-urethane scaffolds were electro-spun and underwent uniaxial tensile testing in and transverse to the direction of predominant fibre alignment before and after in vitro degradation of up to 28 days. A microstructurally-based transversely isotropic hyperelastic continuum constitutive formulation was developed and its parameters were identified from the experimental stress-strain data of the scaffolds at various stages of degradation. During scaffold degradation, maximum stress and strain in circumferential direction decreased from 1.02 ± 0.23 MPa to 0.38 ± 0.004 MPa and from 46 ± 11 % to 12 ± 2 %, respectively. In longitudinal direction, maximum stress and strain decreased from 0.071 ± 0.016 MPa to 0.010 ± 0.007 MPa and from 69 ± 24 % to 8 ± 2 %, respectively. The constitutive parameters were identified for both directions of the non-degraded and degraded scaffold for strain range varying between 0% and 16% with coefficients of determination r(2)>0.871. The six-parameter constitutive formulation proved versatile enough to capture the varying non-linear transversely isotropic behaviour of the fibrous scaffold throughout various stages of degradation.

  17. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  18. Electrocoagulation pretreatment of wet-spun acrylic fibers manufacturing wastewater to improve its biodegradability.

    PubMed

    Gong, Chenhao; Zhang, Zhongguo; Li, Haitao; Li, Duo; Wu, Baichun; Sun, Yuwei; Cheng, Yanjun

    2014-06-15

    The electrocoagulation (EC) process was used to pretreat wastewater from the manufacture of wet-spun acrylic fibers, and the effects of varying the operating parameters, including the electrode area/wastewater volume (A/V) ratio, current density, interelectrode distance and pH, on the EC treatment process were investigated. About 44% of the total organic carbon was removed using the optimal conditions in a 100 min procedure. The optimal conditions were a current density of 35.7 mA cm(-2), an A/V ratio of 0.28 cm(-1), a pH of 5, and an interelectrode distance of 0.8 cm. The biodegradability of the contaminants in the treated water was improved by the EC treatment (using the optimal conditions), increasing the five-day biological oxygen demand/chemical oxygen demand ratio to 0.35, which could improve the effectiveness of subsequent biological treatments. The improvement in the biodegradability of the contaminants in the wastewater was attributed to the removal and degradation of aromatic organic compounds, straight-chain paraffins, and other organic compounds, which we identified using gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy. The EC process was proven to be an effective alternative pretreatment for wastewater from the manufacture of wet-spun acrylic fibers, prior to biological treatments.

  19. Geology and geochemistry of Summitville, Colorado: an epithermal acid sulfate deposit in a volcanic dome

    USGS Publications Warehouse

    Gray, J.E.; Coolbaugh, M.F.

    1994-01-01

    Geologic studies during recent open-pit mining at Summitville, Colorado, have provided new information on an epithermal acid sulfate Au-Ag-Cu deposit formed in a volcanic dome. Geologic mapping, geochemical studies of whole-rock samples from blast holes, and geologic and geochemical traverse studies refine the details of the evolution of the Summitville deposit. Six distinct events followed emplacement of the quartz latite volcanic dome and define the development of the Summitville deposit: 1) an early stage of acid sulfate alteration, 2) subsequent Cu sulfide and gold mineralization, 3) widespread hydrothermal brecciation, 4) volumetrically minor, base metal sulfide-bearing barite veining, 5) volumetrically minor, kaolinite matrix brecciation, and finally, 6) supergene oxidation. -from Authors

  20. Space deployable domed solar concentrator with foldable panels and hinge therefor

    NASA Technical Reports Server (NTRS)

    Grayson, Fred G. (Inventor); Miller, Warren H. (Inventor); Sturgis, James D. (Inventor)

    1989-01-01

    A space deployable solar energy concentrator is formed of a dome-shaped arrangement of compactly stowable flat panel segments mounted on a collapsible, space-deployable support structure of interconnected linear components. The support structure is comprised of a plurality of tensioned, curvilinear edge strips which extend in a radial direction from a prescribed vertex of a surrounding umbrella-like framework of radially extending rib members. Between a respective pair of radially-extending, curvilinear edge strips an individual wedge-shaped panel section is formed of a plurality of multi-segment lens panel strips each of which is supported in tension between the pair of edge strips by a pair of circumferentially extending catenary cord members connected to a pair of ribs of the surrounding umbrella-like framework. A respective lens panel strip is comprised of a plurality of flat, generally rectangular-shaped, energy-directing panels arranged side-by-side in the circumferential direction of the dome. Adjacent panels are interconnected by flexible U-shaped hinges which overlap opposing edges of adjacent panels and engage respective cylindrically-shaped, load distribution bars that slide within the flexible hinges. Because each U-shaped hinge is flexible, it is permitted to shift in the circumferential direction of the panel section to facilitate stowage and deployment of the dome.

  1. 1. PARKING LOT AT GLACIER POINT. HALF DOME AT CENTER ...

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

    1. PARKING LOT AT GLACIER POINT. HALF DOME AT CENTER REAR. LOOKING NE. GIS: N-36 43 45.8 / W-119 34 14.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

  2. Devon Energy Production Company – Riverton Dome NPDES Permit

    EPA Pesticide Factsheets

    Under NPDES permit WY-0000671, Devon Energy Production Company, L.P. – Riverton Dome is authorized to discharge from its wastewater treatment facility located in Fremont County, Wyoming to the Little Wind River via unnamed draw.

  3. Wesco Operating, Inc. – Sheldon Dome Field NPDES Permit

    EPA Pesticide Factsheets

    Under NPDES permit WY-0025607, Wesco Operating, Inc. is authorized to discharge from its Sheldon Dome Field wastewater treatment facility in Fremont County, Wyo. to an unnamed ephemeral tributary of Dry (Pasup) Creek, which is tributary to the Wind River.

  4. 4. FACING EAST ACROSS BRIDGE AT HALF DOME WITH BICYCLE ...

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

    4. FACING EAST ACROSS BRIDGE AT HALF DOME WITH BICYCLE PATH MARKERS IN FOREGROUND AND ELECTRICAL TRANSFORMER FOR CAMPGROUND TO RIGHT. - Ahwahnee Bridge, Spanning Merced River on service road, Yosemite Village, Mariposa County, CA

  5. Phoenix Production Company – Sheldon Dome Field NPDES Permit

    EPA Pesticide Factsheets

    Under NPDES permit WY-0024953, Phoenix Production Company is authorized to discharge from its Sheldon Dome Field wastewater treatment facility in Fremont County, Wyoming, to an unnamed ephemeral tributary of Dry Creek, which is tributary to the Wind River.

  6. 4. WASHBURN POINT VISTA AREA. HALF DOME AT CENTER REAR. ...

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

    4. WASHBURN POINT VISTA AREA. HALF DOME AT CENTER REAR. LOOKING NE. GIS: N-37 43 13.7 / W-119 34 23.0 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

  7. 5. GLACIER POINT ROAD VIEW AT SENTINEL DOME PARKING AREA. ...

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

    5. GLACIER POINT ROAD VIEW AT SENTINEL DOME PARKING AREA. LOOKING E. GIS: N-37 42 43.8 / W-119 35 12.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

  8. DETAIL OF DOMED BOTTOM, ALTITUDE CHAMBER R, FACING EAST ...

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

    DETAIL OF DOMED BOTTOM, ALTITUDE CHAMBER R, FACING EAST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

  9. DETAIL OF DOMED BOTTOM, ALTITUDE CHAMBER L, FACING NORTHWEST ...

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

    DETAIL OF DOMED BOTTOM, ALTITUDE CHAMBER L, FACING NORTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

  10. DETAIL VIEW OF BRIDGE CRANE USED TO LIFT DOMED LIDS ...

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

    DETAIL VIEW OF BRIDGE CRANE USED TO LIFT DOMED LIDS OF THE ALTITUDE CHAMBERS, FACING SOUTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

  11. DETAIL OF THE EXTERIOR OF THE DOMED LID, ALTITUDE CHAMBER ...

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

    DETAIL OF THE EXTERIOR OF THE DOMED LID, ALTITUDE CHAMBER R, FACING NORTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

  12. DETAIL OF THE INTERIOR OF THE DOMED LID, ALTITUDE CHAMBER ...

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

    DETAIL OF THE INTERIOR OF THE DOMED LID, ALTITUDE CHAMBER R, FACING NORTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL

  13. Southeast Elevation; Dome Rafter Detail; Piazza Rafter Detail; Main Block ...

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

    Southeast Elevation; Dome Rafter Detail; Piazza Rafter Detail; Main Block Bracket Detail - National Home for Disabled Volunteer Soldiers - Battle Mountain Sanitarium, Administration Building, 500 North Fifth Street, Hot Springs, Fall River County, SD

  14. Wesco Operating, Inc. – Winkleman Dome Field NPDES Permit

    EPA Pesticide Factsheets

    Under NPDES permit WY-0025232, Wesco Operating, Inc. is authorized to discharge from its Winkleman Dome Field wastewater treatment facility in Fremont County, Wyo. to an unnamed ephemeral tributary of Big Horn Draw, a tributary to the Little Wind River.

  15. Contrasting Sources Of Granites In The Fosdick Migmatite Dome, West Antarctica

    NASA Astrophysics Data System (ADS)

    Saito, S.; Brown, M.; Korhonen, F.; Siddoway, C. S.

    2007-12-01

    suggest that the granites and leucosomes likely formed by partial melting of the Ford Granodiorite or a sedimentary protolith represented by the Swanson Formation. In terms of trace element compositions, the granites in the dome may be grouped into high-Sr and low-Sr type. Our initial Sr-Nd isotope data suggest that sources of the high-Sr and low-Sr granites are the Ford Granodiorite and the Swanson Formation, respectively. The difference in Sr contents of two granite types may be attributed to different hydrate-breakdown melting reactions in the contrasting sources. Mica-breakdown melting will not contribute a significant amount of Sr to the melt, so we infer that the low-Sr granite likely formed by a mica-breakdown melting reaction in the metasedimentary source. In contrast, hornblende-breakdown melting or hornblende-biotite-breakdown melting of a granodiorite source may contribute Sr to the melt, and we infer the high-Sr granite likely formed by this process. Continuing research will investigate whether these attributes may be used for correlation with contemporaneous magmatism recorded in contiguous parts of the East Gondwana margin, particularly New Zealand (e.g. Tulloch and Kimbrough, 2003, GSA SP374) or Thurston Island (e.g. Bradshaw et al., 1997, Ter. Ant. Pub.).

  16. Preliminary paragenetic interpretation of the Quaternary topaz rhyolite lava domes of the Blackfoot volcanic field, southeastern Idaho

    NASA Astrophysics Data System (ADS)

    Lochridge, W. K., Jr.; McCurry, M. O.; Goldsby, R.

    2015-12-01

    The Quaternary topaz rhyolite lava domes of the bimodal, basalt-dominated Blackfoot volcanic field (BVF), SE Idaho occur in three clusters. We refer to these as the China Hat lava dome field (southernmost; ~ 57 ka), and the 1.4 to 1.5 Ma Sheep Island and White Mountain (northernmost) lava dome fields. The rhyolites and surrounding, more voluminous basalt lavas closely resemble coeval Quaternary rocks erupted to the north along the Eastern Snake River Plain segment of the Yellowstone-Snake River Plain volcanic track. However rhyolites in BVF are distinguished by having more evolved Sr- and Nd-isotopic ratios, as well as having phenocryst assemblages that includes hydrous phases (biotite and hornblende), thorite, and vapor-phase topaz. This study seeks to improve our understanding of the unique conditions of magma evolution that led to these differences. We focus on textural features of major and accessory phenocrysts as a basis for inferring paragenesis for rhyolites from the China Hat lava dome field. Preliminary work indicates that there are three sequentially formed populations of textures among magmatic phases: 1. population of anhedral quartz and plagioclase; 2. population of euhedral grains that includes quartz, sandine, plagioclase, biotite, hornblende, Fe-Ti oxides, zircon and apatite; 3. boxy cellular (skeletal?) sanidine and quartz. We speculate that the first population are resorbed antecrysts, the second formed prior to eruption as autocrysts (at or near equilibrium?), and the third formed soon before or during eruption.

  17. Phase competition in trisected superconducting dome

    PubMed Central

    Vishik, I. M.; Hashimoto, M.; He, Rui-Hua; Lee, Wei-Sheng; Schmitt, Felix; Lu, Donghui; Moore, R. G.; Zhang, C.; Meevasana, W.; Sasagawa, T.; Uchida, S.; Fujita, Kazuhiro; Ishida, S.; Ishikado, M.; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Hussain, Zahid; Devereaux, Thomas P.; Shen, Zhi-Xun

    2012-01-01

    A detailed phenomenology of low energy excitations is a crucial starting point for microscopic understanding of complex materials, such as the cuprate high-temperature superconductors. Because of its unique momentum-space discrimination, angle-resolved photoemission spectroscopy (ARPES) is ideally suited for this task in the cuprates, where emergent phases, particularly superconductivity and the pseudogap, have anisotropic gap structure in momentum space. We present a comprehensive doping- and temperature-dependence ARPES study of spectral gaps in Bi2Sr2CaCu2O8+δ, covering much of the superconducting portion of the phase diagram. In the ground state, abrupt changes in near-nodal gap phenomenology give spectroscopic evidence for two potential quantum critical points, p = 0.19 for the pseudogap phase and p = 0.076 for another competing phase. Temperature dependence reveals that the pseudogap is not static below Tc and exists p > 0.19 at higher temperatures. Our data imply a revised phase diagram that reconciles conflicting reports about the endpoint of the pseudogap in the literature, incorporates phase competition between the superconducting gap and pseudogap, and highlights distinct physics at the edge of the superconducting dome. PMID:23093670

  18. Erosion studies of infrared dome materials

    NASA Astrophysics Data System (ADS)

    Sullivan, Roger M.; Phelps, Andrew; Kirsch, James A.; Welsh, Earle A.; Harris, Daniel C.

    2007-04-01

    The testing reported in this paper operationalized the material requirement: An infrared transparent dome material must be at least as good as magnesium fluoride in rain tests and substantially better than magnesium fluoride in sand tests. Sand erosion test conclusions, based on changes in midwave infrared transmission, are that Cleartran TM with the protective coating system tested is not substantially more resistant to large grain sand erosion damage than magnesium fluoride. ALON TM and spinel are substantially more resistant to large grain sand erosion damage than magnesium fluoride. There is no significant transmission difference due to small grain sand erosion observed between any of the tested coupons. Qualitative analysis of coupon damage after exposure to an artificial rain field on a whirling arm showed that ALON TM and spinel are at least as rain erosion resistant as magnesium fluoride, but the coated Cleartran TM coupons delaminated rapidly under the same rain test conditions. Testing coupons exposed sequentially to the milder sand condition followed by the whirling arm rain erosion test demonstrated that magnesium fluoride rain resistance is diminished in the combined test, but that ALON TM and spinel retain their robust resistance. Coated Cleartran TM delaminated under the combined conditions as well. It is noteworthy that the results reported for the midwave infrared range also apply to the near infrared region above 1 micron.

  19. Solar Photovoltaic Array With Mini-Dome Fresnel Lenses

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F., Jr.; O'Neill, Mark J.

    1994-01-01

    Mini-dome Fresnel lenses concentrate sunlight onto individual photovoltaic cells. Facets of Fresnel lens designed to refract incident light at angle of minimum deviation to minimize reflective losses. Prismatic cover on surface of each cell reduces losses by redirecting incident light away from metal contacts toward bulk of semiconductor, where it is usefully absorbed. Simple design of mini-dome concentrator array easily adaptable to automated manufacturing techniques currently used by semiconductor industry. Attractive option for variety of future space missions.

  20. Internal Convection on Ceres: A Possible Explanation for Dome Formation

    NASA Astrophysics Data System (ADS)

    Travis, B. J.; Feldman, W. C.; Sizemore, H. G.; O'Brien, D. P.; Sykes, M. V.

    2015-12-01

    Numerical 2-D whole-body simulations of the evolution of Ceres' internal dynamics and thermal structure over its history indicate that hydrothermal activity is very strong throughout the first half of Ceres' history, gradually weakening thereafter, but still active even today (Travis et al, 2015, 46th LPSC). Large-scale upwelling plumes of muddy water extend from the porous, permeable rocky core through an ocean layer and impinge on the bottom of the ice shell. These upwellings are very long-lasting. In addition, small scale, shorter-lived plumes frequently develop on the upper regions of the large plumes. The large-scale plumes occur at roughly +/- 25 o latitude. Recently, 3-D simulations of a sector of Ceres shows that the upwellings are indeed plumes and not sheets. In the 3-D model, plume diameters in the model are as small as 15-20 km in diameter, up to several 10s of km or more. Relating internal dynamics to surface features is challenging. Linkage to mounds seen on the surface may be possible. There appear to be two classes of mounds: Large domes (10s of km diameter) and small (<15 km diameter). Morphological evidence such as embayment relations imply that large mounds may be extrusive. The source of the small domes is less clear. They could be extrusive, or they could be pingo-like structures that form when large areas of melt are extruded or produced by impact, although they are larger than terrestrial or martian structures. Mound heights are typically no more than 1 - 5 km. One mechanism for generation of these mounds suggested by our modeling is extrusion of mud through fractures in the icy crust. Over-pressuring of upwelling plumes at the base of the icy crust from freezing of neighboring downwellings could generate fractures in a frozen mud crust. As plumes and icy crust cool, a significant volume expansion occurs due to freezing of water to ice. This pressurization is not uniform in space; the still-liquid upwellings will experience overpressure in

  1. Catastrophic lava dome failure at Soufrière Hills Volcano, Montserrat, 12-13 July 2003

    USGS Publications Warehouse

    Herd, Richard A.; Edmonds, Marie; Bass, Venus A.

    2005-01-01

    The lava dome collapse of 12–13 July 2003 was the largest of the Soufrière Hills Volcano eruption thus far (1995–2005) and the largest recorded in historical times from any volcano; 210 million m3 of dome material collapsed over 18 h and formed large pyroclastic flows, which reached the sea. The evolution of the collapse can be interpreted with reference to the complex structure of the lava dome, which comprised discrete spines and shear lobes and an apron of talus. Progressive slumping of talus for 10 h at the beginning of the collapse generated low-volume pyroclastic flows. It undermined the massive part of the lava dome and eventually prompted catastrophic failure. From 02:00 to 04:40 13 July 2003 large pyroclastic flows were generated; these reached their largest magnitude at 03:35, when the volume flux of material lost from the lava dome probably approached 16 million m3 over two minutes. The high flux of pyroclastic flows into the sea caused a tsunami and a hydrovolcanic explosion with an associated pyroclastic surge, which flowed inland. A vulcanian explosion occurred during or immediately after the largest pyroclastic flows at 03:35 13 July and four further explosions occurred at progressively longer intervals during 13–15 July 2003. The dome collapse lasted approximately 18 h, but 170 of the total 210 million m3 was removed in only 2.6 h during the most intense stage of the collapse.

  2. Structure Study of Cellulose Fibers Wet-Spun from Environmentally Friendly NaOH/Urea Aqueous Solutions

    SciTech Connect

    Chen,X.; Burger, C.; Wan, F.; Zhang, J.; Rong, L.; Hsiao, B.; Chu, B.; Cai, J.; Zhang, L.

    2007-01-01

    In this study, structure changes of regenerated cellulose fibers wet-spun from a cotton linter pulp (degree of polymerization {approx}620) solution in an NaOH/urea solvent under different conditions were investigated by simultaneous synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). WAXD results indicated that the increase in flow rate during spinning produced a better crystal orientation and a higher degree of crystallinity, whereas a 2-fold increase in draw ratio only affected the crystal orientation. When coagulated in a H{sub 2}SO{sub 4}/Na{sub 2}SO{sub 4} aqueous solution at 15 {sup o}C, the regenerated fibers exhibited the highest crystallinity and a crystal orientation comparable to that of commercial rayon fibers by the viscose method. SAXS patterns exhibited a pair of meridional maxima in all regenerated cellulose fibers, indicating the existence of a lamellar structure. A fibrillar superstructure was observed only at higher flow rates (>20 m/min). The conformation of cellulose molecules in NaOH/urea aqueous solution was also investigated by static and dynamic light scattering. It was found that cellulose chains formed aggregates with a radius of gyration, R{sub g}, of about 232 nm and an apparent hydrodynamic radius, R{sub h}, of about 172 nm. The NaOH/urea solvent system is low-cost and environmentally friendly, which may offer an alternative route to replace more hazardous existing methods for the production of regenerated cellulose fibers.

  3. Collagen solubility testing, a quality assurance step for reproducible electro-spun nano-fibre fabrication. A technical note.

    PubMed

    Zeugolis, D I; Li, B; Lareu, R R; Chan, C K; Raghunath, M

    2008-01-01

    Collagen is the main component of the extra-cellular matrix and has been utilised for numerous clinical applications in many forms and products. However, since collagen remains a natural animal-derived biopolymer, variation between batches should be addressed and minimised to ensure reproducibility of the fabrication process. Recently, electro-spinning of collagen has been introduced as a leading technique for the production of bio-mimetic nano-scale scaffolds for tissue-engineering applications. However, no protocols are available that would allow comparisons of the quality of different collagen raw materials prior to the electro-spinning process. In order to bridge this gap we assessed the solubility of various freeze-dried collagens in 0.5 M acetic acid and analysed the solved collagen by gel electrophoresis. We show that raw material of limited solubility in acetic acid will not render high quality electro-spun nano-fibres using hexafluoropropanol. In particular, insoluble collagen directly failed to produce nano-fibres, collagen of reduced solubility produced fused nano-fibres with limited inter-nano-fibre space, whilst purified type-I collagen of high solubility produced smooth, reproducible nano-fibres. Gel electrophoresis confirmed the amount of solubility, as well as qualitative differences in terms of collagen cross-links and collagen types. We recommend this simple and fast step to save costs and to enhance control over the electro-spinning process of collagen. Furthermore, we believe that the solubility test should be introduced prior to any collagenous matrix preparation in order to ensure reproducibility and accuracy.

  4. Modified sensing element of a fibre-optic current sensor based on a low-eigenellipticity spun fibre

    SciTech Connect

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P

    2014-10-31

    We have proposed and investigated a modified sensing element of a spun fibre current sensor for the case when the beat length of the built-in linear birefringence of the fibre is equal to or less than the spin pitch of its helical structure. The proposed configuration makes it possible to restore the interferometer contrast reduced because of the decrease in the ellipticity of the wavelength-averaged polarisation state of radiation propagating in such spun fibre. The modified sensing element contains two polarisation state converters: one, located at the spun fibre input, produces polarisation with ellipticity equal to the eigenellipticity of the fibre, and the other ensures conversion of the elliptical polarisation to an orthogonal one through mirror reflection at the fibre output. We have also demonstrated that the magneto-optical sensitivity decreases slightly for the analysed spectrum-averaged parameters of the polarisation state of radiation in the spun fibre. Experimental data lend support to the theoretical predictions. (fibre-optic sensors)

  5. Gradient Distribution of Martensite Phase in Melt-Spun Ribbons of a Fe-Ni-Ti-Al Alloy.

    PubMed

    Bondar, Volodymyr; Danilchenko, Vitalij; Dzevin, Ievgenij

    2016-12-01

    Metallographic, X-ray diffraction and magnetometric analysis were used to study the regularities of martensitic transformation in melt-spun ribbons of a Fe - 28 wt. % Ni - 2.1 wt. % Ti - 2 wt. % Al - 0.05 wt. % C alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin melt-spun ribbons of the alloy are related to the size effect of the transformation and structural inhomogeneity of the ribbons. The distribution of austenitic grain size in different local areas of melt-spun ribbons is significantly different. The principal factor for changing the completeness of the martensitic transformation is the size effect of transformation. Difference in the martensite volume fraction in local regions of a ribbon is mainly determined by the different volume fractions of ultrafine-grained (500-1000 nm) and nanosized (80-100 nm and less) initial austenite grains, in which the transformation was slowed down or completely suppressed. Other factors almost do not affect the completeness of the martensitic transformation. The strong stabilizing effect of the reverse α-γ transformation with respect to the subsequent direct γ-α transformation in the melt-spun ribbons is also related to the grain size effect.

  6. Gradient Distribution of Martensite Phase in Melt-Spun Ribbons of a Fe-Ni-Ti-Al Alloy

    NASA Astrophysics Data System (ADS)

    Bondar, Volodymyr; Danilchenko, Vitalij; Dzevin, Ievgenij

    2016-02-01

    Metallographic, X-ray diffraction and magnetometric analysis were used to study the regularities of martensitic transformation in melt-spun ribbons of a Fe - 28 wt. % Ni - 2.1 wt. % Ti - 2 wt. % Al - 0.05 wt. % C alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin melt-spun ribbons of the alloy are related to the size effect of the transformation and structural inhomogeneity of the ribbons. The distribution of austenitic grain size in different local areas of melt-spun ribbons is significantly different. The principal factor for changing the completeness of the martensitic transformation is the size effect of transformation. Difference in the martensite volume fraction in local regions of a ribbon is mainly determined by the different volume fractions of ultrafine-grained (500-1000 nm) and nanosized (80-100 nm and less) initial austenite grains, in which the transformation was slowed down or completely suppressed. Other factors almost do not affect the completeness of the martensitic transformation. The strong stabilizing effect of the reverse α-γ transformation with respect to the subsequent direct γ-α transformation in the melt-spun ribbons is also related to the grain size effect.

  7. Central pit and dome craters - Exposing the interiors of Ganymede and Callisto

    NASA Astrophysics Data System (ADS)

    Schenk, P. M.

    1993-04-01

    Central pit craters on Ganymede and Callisto are an unusual crater class, perhaps related to the unusual properties of water ice. The domes and pits form rapidly, on the time scale of the impact itself, rather than by long-term, post-impact intrusion or extrusion. The bright domes in pit craters are most simply explained as the uplift and exposure of relatively ice-rich material from depths of approximately 3.5 to 5 km during impact. The unusual pit morphology on icy satellites may be the result of impact into crust that is mechanically much weaker at shallow depth than on rocky bodies such as the moon. Because crater morphology is strongly dependent on ice-rock composition, the similarity of pit and dome dimensions on Ganymede and Callisto indicates that the structure and rheology of the crusts of these bodies are very similar, and have been for several billion years. Pit crater morphology indicates that the crusts of both satellites are probably ice-rich and differentiated.

  8. Temporal Evolution of Magma Flow Conditions during Dome Growth, Insights from Numerical Modelling.

    NASA Astrophysics Data System (ADS)

    Chevalier, L. A. C.; Collombet, M.; Pinel, V.

    2015-12-01

    Transitions from effusive to explosive regime at andesitic volcanoes are almost unpredictable at the moment. The reliability of empirical methods based on geophysical precursory patterns is still debated. A better understanding of the physical processes happening in the volcanic system before explosions and associated geophysical signals is needed. At andesitic volcanoes, dome building is often observed during the effusive phase. The weight of a forming dome is expected to have several effects: 1) It obviously induces a ground subsidence in the near field; 2) pressure increase at the top of the conduit causes magma properties and flow conditions evolution; 3) it increases pressure in the surrounding rock such decreasing rock permeability and thus gas loss through the conduit walls, possibly leading to gas pressurisation. Here we use numerical models that couple realistic magma flow conditions in the upper conduit with solid deformation, in 2D axisymmetry, to investigate all these effects. Subsiding effect due to the dome emplacement is simulated by a pressure loading of the rock surrounding the conduit. From realistic initial magma flow conditions in effusive regime (Collombet, 2009), we apply increasing pressure at the conduit top. Volatile solubility increases with pressure, then dome growth causes a decrease of magma porosity and permeability at the top of the conduit. This also causes a decrease of magma viscosity. From magma flow model, we extract pressure and shear stress conditions at the conduit wall, and apply them to the surrounding rock for ground deformation calculation . Darcy flow model is used to study the impacts of permeability decrease inside the conduit and in the surrounding rock on gas loss cinematics. Permeability decrease in the conduit and pressure increase in the surrounding rock cause gas pressurisation.

  9. Interaction of mid-latitude air masses with the polar dome area during RACEPAC and NETCARE

    NASA Astrophysics Data System (ADS)

    Bozem, Heiko; Hoor, Peter; Koellner, Franziska; Kunkel, Daniel; Schneider, Johannes; Schulz, Christiane; Herber, Andreas; Borrmann, Stephan; Wendisch, Manfred; Ehrlich, Andre; Leaitch, Richard; Willis, Megan; Burkart, Julia; Thomas, Jennie; Abbatt, Jon

    2016-04-01

    We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories as well as Flexpart particle dispersion modeling we analyze the transport regimes of mid-latitude air masses traveling to the high Arctic prevalent during spring (RACEPAC 2014, NETCARE 2015) and summer (NETCARE 2014). In general more northern parts of the high Arctic (Lat > 75°N) were relatively unaffected from mid-latitude air masses. In contrast, regions further south are influenced by air masses from Asia and Russia (eastern part of Canadian Arctic and European Arctic) as well as from North America (central and western parts of Canadian Arctic). The transition between the mostly isolated high Arctic and more southern regions indicated by tracer gradients is remarkably sharp. This allows for a chemical definition of the Polar dome based on the variability of CO and CO2 as a marker. Isentropic surfaces that slope from the surface to higher altitudes in the high Arctic form the polar dome that represents a transport barrier for mid-latitude air masses to enter the lower troposphere in the high Arctic. Synoptic-scale weather systems frequently disturb this transport barrier and foster the exchange between air masses from the mid-latitudes and polar regions. This can finally lead to enhanced pollution levels in the lower polar troposphere. Mid-latitude pollution plumes from biomass burning or flaring entering the polar dome area lead to an enhancement of 30% of the observed CO mixing ratio within the polar dome area.

  10. Volcán de Colima dome collapse of July, 2015 and associated pyroclastic density currents

    NASA Astrophysics Data System (ADS)

    Reyes-Dávila, Gabriel A.; Arámbula-Mendoza, Raúl; Espinasa-Pereña, Ramón; Pankhurst, Matthew J.; Navarro-Ochoa, Carlos; Savov, Ivan; Vargas-Bracamontes, Dulce M.; Cortés-Cortés, Abel; Gutiérrez-Martínez, Carlos; Valdés-González, Carlos; Domínguez-Reyes, Tonatiuh; González-Amezcua, Miguel; Martínez-Fierros, Alejandro; Ramírez-Vázquez, Carlos Ariel; Cárdenas-González, Lucio; Castañeda-Bastida, Elizabeth; Vázquez Espinoza de los Monteros, Diana M.; Nieto-Torres, Amiel; Campion, Robin; Courtois, Loic; Lee, Peter D.

    2016-06-01

    During July 10th-11th 2015, Volcán de Colima, Mexico, underwent its most intense eruptive phase since its Subplinian-Plinian 1913 AD eruption. Production of scoria coincident with elevated fumarolic activity and SO2 flux indicate a significant switch of upper-conduit dynamics compared with the preceding decades of dome building and vulcanian explosions. A marked increase in rockfall events and degassing activity was observed on the 8th and 9th of July. On the 10th at 20:16 h (Local time = UTM - 6 h) a partial collapse of the dome generated a series of pyroclastic density currents (PDCs) that lasted 52 min and reached 9.1 km to the south of the volcano. The PDCs were mostly channelized by the Montegrande and San Antonio ravines, and produced a deposit with an estimated volume of 2.4 × 106 m3. Nearly 16 h after the first collapse, a second and larger collapse occurred which lasted 1 h 47 min. This second collapse produced a series of PDCs along the same ravines, reaching a distance of 10.3 km. The total volume calculated for the PDCs of the second event is 8.0 × 106 m3. Including associated ashfall deposits, the two episodes produced a total of 14.2 × 106 m3 of fragmentary material. The collapses formed an amphitheater-shaped crater open towards the south. We propose that the dome collapse was triggered by arrival of gas-rich magma to the upper conduit, which then boiled-over and sustained the PDCs. A juvenile scoria sample selected from the second partial dome collapse contains hornblende, yet at an order of magnitude less abundant (0.2%) than that of 1913, and exhibits reaction rims, whereas the 1913 hornblende is unreacted. At present there is no compelling petrologic evidence for imminent end-cycle activity observed at Volcán de Colima.

  11. Electron holography on remanent magnetization distribution of melt-spun Nd-Fe-B magnets.

    PubMed

    Park, Young-Gil; Shindo, Daisuke

    2004-01-01

    Microstructures and magnetic domain structures of melt-spun Nd-Fe-B permanent magnets were investigated in detail by analytical electron microscopy and electron holography. While the crystal orientation of matrix Nd2Fe14B grains was analyzed by nanobeam electron diffraction, precipitates of a few tens of nanometers at grain boundaries were identified to be alpha-Fe by energy-dispersive X-ray spectroscopy. The detailed magnetization distribution in Nd2Fe14B grains and at their boundaries was visualized by electron holography. Ex situ experimentation with an electromagnet revealed that the domain walls in the demagnetized state and remanent states were pinned at grain boundaries, and Fe precipitates at the grain boundary were situated at the center of the closure domain.

  12. Optimizing Aqua Splicer Parameters for Lycra-Cotton Core Spun Yarn Using Taguchi Method

    NASA Astrophysics Data System (ADS)

    Midha, Vinay Kumar; Hiremath, ShivKumar; Gupta, Vaibhav

    2015-10-01

    In this paper, optimization of the aqua splicer parameters viz opening time, splicing time, feed arm code (i.e. splice length) and duration of water joining was carried out for 37 tex lycra-cotton core spun yarn for better retained splice strength (RSS%), splice abrasion resistance (RYAR%) and splice appearance (RYA%) using Taguchi experimental design. It is observed that as opening time, splicing time and duration of water joining increase, the RSS% and RYAR% increases, whereas increase in feed arm code leads to decrease in both. The opening time and feed arm code do not have significant effect on RYA%. The optimum RSS% of 92.02 % was obtained at splicing parameters of 350 ms opening time, 180 ms splicing time, 65 feed arm code and 600 ms duration of water joining.

  13. Hydrophobic films by atmospheric plasma curing of spun-on liquid precursors.

    PubMed

    Barankin, Michael D; Gonzalez, Eleazar; Habib, Sara B; Gao, Li; Guschl, Peter C; Hicks, Robert F

    2009-02-17

    Hydrophobic coatings have been produced on glass and acrylic samples by using a low-temperature atmospheric pressure plasma to polymerize liquid fluoroalkylsilane precursors. The fluoroalkylsilane precursor was dissolved in isooctane and spun onto the substrate at 550 rpm. The sample was then exposed to the reactive species generated from a nitrogen plasma. The plasma was operated with 2.3 vol % N2 in helium at 7.4 W/cm2 at a radio frequency of 27.12 MHz. The total and polar component of the coating's surface energy was found to equal 11.0 and 1.2 dyn/cm, respectively. Average water contact angles of 110 degrees and 106 degrees were measured on the coated glass and acrylic surfaces, respectively. X-ray photoelectron spectroscopy revealed that, after treatment, the fluoroalkyl ligands remained intact on the Si atoms, with a F/C atomic ratio of 2.23.

  14. Magnetostructural transformation and magnetocaloric effect in Mn-Ni-Sn melt-spun ribbons

    NASA Astrophysics Data System (ADS)

    Jiang, Yiwen; Li, Zongbin; Li, Zhenzhuang; Yang, Yiqiao; Yang, Bo; Zhang, Yudong; Esling, Claude; Zhao, Xiang; Zuo, Liang

    2017-01-01

    The martensitic transformation and magnetic properties of Mn50Ni50- x Sn x (7≤ x≤ 10) melt-spun ribbons were investigated. It is shown that the increase of Sn content results in a nearly linear decrease of martensitic transformation temperatures in the ribbons, with an average rate of 70 K per at % of Sn. In Mn50Ni40Sn10 ribbons, the field-induced reverse martensitic transformation from a weak magnetic martensite to a ferromagnetic austenite was realized due to the strong magnetostructural coupling. Under a field change of 5T, the large magnetic entropy change of 13.7 J kg-1K-1 and the effective refrigerant capacity of 72.9 Jkg-1 were obtained in Mn50Ni40Sn10 ribbons.

  15. Effect of magnetic fields on melt-spun Nd2Fe14B-based ribbons

    NASA Astrophysics Data System (ADS)

    Van Nguyen, Vuong; Rong, Chuanbing; Ding, Yong; Liu, J. Ping

    2012-04-01

    The effect of a magnetic field on microstructure and magnetic properties of Nd2Fe14B-based melt-spun ribbons is investigated. The magnetic field was applied in perpendicular or parallel direction to the ribbon plane during quench with a field strength up to several kilo Oersteds. The XRD patterns and TEM graphs show a strong grain size reduction upon the magnetic field application. The magnetic field also enhances the (00l) texture of ribbons when the field is perpendicular to the ribbon plane. The refined microstructure with significantly reduced grain size leads to enhanced magnetic exchange interactions between the hard and soft phases in the Nd2Fe14B/Fe nanocomposite ribbons. This magnetic field-assisted melt-spinning technique is promising for producing nanocomposite magnets with enhanced energy density.

  16. Cellular microstructure of chill block melt spun Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Glasgow, T. K.

    1987-01-01

    Chill block melt spun ribbons of Ni-Mo binary alloys containing 8.0 to 41.8 wt pct Mo have been prepared under carefully controlled processing conditions. The growth velocity has been determined as a function of distance from the quench surface from the observed ribbon thickness dependence on the melt puddle residence time. Primary arm spacings measured at the midribbon thickness locations show a dependence on growth velocity and alloy composition which is expected from dendritic growth models for binary alloys directionally solidified in a positive temperature gradient. Microsegregation across cells and its variation with distance from the quench surface and alloy composition have been examined and compared with theoretical predictions.

  17. High-coercivity samarium-iron-nitrogen from nitriding melt-spun ribbons

    NASA Astrophysics Data System (ADS)

    Pinkerton, F. E.; Fuerst, C. D.

    1993-04-01

    Melt spinning has proven to be an excellent technique for magnetic hardening of a variety of permanent magnet materials, especially Nd-Fe-B. Recently, a new permanent magnet material has been discovered by nitriding the compound Sm2Fe17 to obtain Sm2Fe17Nx. The authors have obtained magnetically hard Sm-Fe-N ribbons with a room-temperature intrinsic coercivity H ci = 22 kOe (1.8 MA/m) by nitriding melt-spun Sm-Fe precursor ribbons. Best results were obtained by grinding the ribbons to a <25 µm powder, then heat treating the powder in vacuum for 1 h at 700 °C prior to nitriding in N2 gas at 450 to 480 °C. X-ray diffraction shows that the primary phase is TbCu7-type Sn2Fe17Nx, a disordered hexagonal modification of the rhombohedral Snu2Fe17 phase.

  18. Effects of protein molecular weight on the intrinsic material properties and release kinetics of wet spun polymeric microfiber delivery systems.

    PubMed

    Lavin, Danya M; Zhang, Linda; Furtado, Stacia; Hopkins, Richard A; Mathiowitz, Edith

    2013-01-01

    Wet spun microfibers have great potential for the design of multifunctional controlled release scaffolds. Understanding aspects of drug delivery and mechanical strength, specific to protein molecular weight, may aid in the optimization and development of wet spun fiber platforms. This study investigated the intrinsic material properties and release kinetics of poly(l-lactic acid) (PLLA) and poly(lactic-co-glycolic acid) (PLGA) wet spun microfibers encapsulating proteins with varying molecular weights. A cryogenic emulsion technique developed in our laboratory was used to encapsulate insulin (5.8 kDa), lysozyme (14.3 kDa) and bovine serum albumin (BSA, 66.0 kDa) within wet spun microfibers (~100 μm). Protein loading was found to significantly influence mechanical strength and drug release kinetics of PLGA and PLLA microfibers in a molecular-weight-dependent manner. BSA encapsulation resulted in the most significant decrease in strength and ductility for both PLGA and PLLA microfibers. Interestingly, BSA-loaded PLGA microfibers had a twofold increase (8±2 MPa to 16±1 MPa) in tensile strength and a fourfold increase (3±1% to 12±6%) in elongation until failure in comparison to PLLA microfibers. PLGA and PLLA microfibers exhibited prolonged protein release up to 63 days in vitro. Further analysis with the Korsmeyer-Peppas kinetic model determined that the mechanism of protein release was dependent on Fickian diffusion. These results emphasize the critical role protein molecular weight has on the properties of wet spun filaments, highlighting the importance of designing small molecular analogues to replace growth factors with large molecular weights.

  19. Damping characteristics of the Ti-rich TiNi melt-spun ribbon measured by using a dynamic mechanical analyzer

    NASA Astrophysics Data System (ADS)

    Chang, S. H.; Chen, T. H.; Wu, S. K.; Lin, K. N.

    2010-05-01

    Damping characteristics of melt-spun Ti51Ni49 ribbons are investigated by using a dynamic mechanical analyzer (DMA). The as-spun Ti51Ni49 ribbons are crystalline and possess a uniform grain size distribution with an average diameter of 3 μm. The DMA results reveal that the tan δ value of the martensitic transformation peak increases with an increase in the temperature rate and applied deformation amplitude but decreases with an increase in the deformation frequency. Compared to amorphous or crystallized Ti50Ni25Cu25 melt-spun ribbons, the as-spun Ti51Ni49 ribbon was found to have a higher damping capacity during martensitic transformation when DMA tests were conducted at a cooling rate of 3 °C min-1 and a deformation frequency of 10 Hz. Besides, the as-spun Ti51Ni49 ribbon also exhibits a much higher inherent internal friction than bulk Ti50Ni50 or Ti51Ni39Cu10 shape memory alloys under isothermal conditions. The Ti51Ni49 melt-spun ribbon does not exhibit a relaxation peak, which is usually obtained in bulk Ti-Ni-based alloys or crystallized Ti50Ni25Cu25 melt-spun ribbons at about -75 °C in the DMA tan δ curve.

  20. Wind tunnel study of an observatory dome with a circular aperture

    NASA Technical Reports Server (NTRS)

    Zilliac, Gregory G.; Cliffton, Ethan W.

    1990-01-01

    Results of a wind tunnel test of a new concept in observatory dome design, the Fixed Shutter Dome are presented. From an aerodynamic standpoint, the new dome configuration is similar in overall shape to conventional observatory domes, with the exception of the telescope viewing aperture. The new design consists of a circular aperture of reduced area in contrast to conventional domes with rectangular or slotted openings. Wind tunnel results of a side-by-side comparison of the new dome with a conventional dome demonstrate that the mean and fluctuating velocity through the aperture and in the center of the new dome configuration are lower than those of conventional domes, thus reducing the likelihood of telescope flow-induced vibration.

  1. Explosive activity associated with the growth of volcanic domes

    USGS Publications Warehouse

    Newhall, C.G.; Melson, W.G.

    1983-01-01

    Domes offer unique opportunities to measure or infer the characteristics of magmas that, at domes and elsewhere, control explosive activity. A review of explosive activity associated with historical dome growth shows that: 1. (1) explosive activity has occurred in close association with nearly all historical dome growth; 2. (2) whole-rock SiO2 content, a crude but widely reported indicator of magma viscosity, shows no systematic relationship to the timing and character of explosions; 3. (3) the average rate of dome growth, a crude indicator of the rate of supply of magma and volatiles to the near-surface enviornment, shows no systematic relationship to the timing or character of explosions; and 4. (4) new studies at Arenal and Mount St. Helens suggest that water content is the dominant control on explosions from water-rich magmas, whereas the crystal content and composition of the interstitial melt (and hence magma viscosity) are equally or more important controls on explosions from water-poor magmas. New efforts should be made to improve current, rather limited techniques for monitoring pre-eruption volatile content and magma viscosity, and thus the explosive potential of magmas. ?? 1983.

  2. Contemporary doming of the Adirondack mountains: Further evidence from releveling

    USGS Publications Warehouse

    Isachsen, Y.W.

    1981-01-01

    The Adirondack Mountains constitute an anomalously large, domical uplift on the Appalachian foreland. The dome has a NNE-SSW axis about 190 km long, and an east-west dimension of about 140 km. It has a structural relief of at least 1600 m, and a local topographic relief of up to 1200 m. First-order leveling in 1955, and again in 1973 along a north-south line at the eastern margin of the Adirondack shows an uplift rate of 2.2 mm/yr at the latitude of the center of the dome and a subsidence rate of 2.8 mm/yr at the northern end of the line near the Canadian border. The net amount of arching along this releveled line is 9 cm ?? 2 cm (Isachsen, 1975). To test the idea that this arching represented an "edge effect" of contemporary doming of the Adirondacks as a whole, the National Geodetic Survey was encouraged to relevel a 1931 north-south line between Utica and Fort Covington (near the Canadian border) which crosses the center of the dome. The releveling showed that the mountain mass is undergoing contemporary domical uplift at a rate which reaches 3.7 mm/yr near the center of the dome (compare with 1 mm/yr for the Swiss Alps). Three other releveled lines in the area support this conclusion. ?? 1981.

  3. Dry Creek salt dome, Mississippi Interior Salt basin

    SciTech Connect

    Montgomery, S.L.; Ericksen, R.L.

    1997-03-01

    Recent drilling of salt dome flanks in the Mississippi Salt basin has resulted in important new discoveries and the opening of a frontier play. This play is focused on gas/condensate reserves in several Cretaceous formations, most notably the Upper Cretaceous Eutaw and lower Tuscaloosa intervals and Lower Cretaceous Paluxy and Hosston formations. As many as eight domes have been drilled thus far; sandstones in the upper Hosston Formation comprise the primary target. Production has been as high as 3-5 Mcf and 500-1200 bbl of condensate per day, with estimated ultimate reserves in the range of 0.2 to 1.5 MBOE (million barrels oil equivalent) per well. As typified by discovery at Dry Creek salt dome, traps are related to faulting, unconformities, and updip loss of permeability. Previous drilling at Dry Creek, and in the basin generally, avoided the flank areas of most domes, due to geologic models that predicted latestage (Tertiary) piercement and breached accumulations. Recent data from Dry Creek and other productive domes suggest that growth was episodic and that piercement of Tertiary strata did not affect deeper reservoirs charged with hydrocarbons in the Late Cretaceous.

  4. Fracture fillings and intrusive pyroclasts, Inyo Domes, California

    SciTech Connect

    Heiken, G.; Wohletz, K.; Eichelberger, J.

    1988-05-10

    Fractures containing juvenile magmatic pyroclasts were encountered during drilling into a 600-year-old feeder dike beneath the Inyo Domes chain, California. The Inyo Domes consist of a north-south trending, 10-km-long chain of domes, rhyolitic tuff rings, and phreatic craters. Boreholes were cored through the 51-m-diameter conduit of Obsidian Dome, the largest of the Inyo Domes, and through an unvented portion of the intrusion (dike) 1 km to the south. Pyroclast-bearing fractures were intersected in both holes: (1) 7- to 40-cm-thick fractures in welded basaltic scoria and quartz monzonite country rock are adjacent to the conduit at depths of 400--411 m and 492--533 m; they contain gray, clastic deposits, which show truncated cross bedding and convolute bedding; (2) adjacent to the dike, massive fracture fillings occur at depths of 289--302 m (129 m east of the dike) and 366--384 m (95--87 m east of the dike).

  5. Lava dome morphometry and geochronology of the youngest eruptive activity in Eastern Central Europe: Ciomadul (Csomád), East Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Karátson, D.; Telbisz, T.; Harangi, Sz.; Magyari, E.; Kiss, B.; Dunkl, I.; Veres, D.; Braun, M.

    2012-04-01

    Volcanic evolution of the Ciomadul (Csomád) lava dome complex, site of the youngest (Late Pleistocene, late Marine Isotope Stage 3) eruptive activity in the Carpathians, has been studied by advanced morphometry and radiometric (U/Pb, U/He and 14C) geochronology. The volcano produced alternating effusive and intermittent explosive eruptions from individual domes, typical of common andesitic-dacitic lava domes. A comparative morphometry shows steep ≥30° mean slopes of domes' upper flank and the Csomád domes fit well to the 100-200 ka domes worldwide. Morphometric ages obtained from the mean slope vs age precipitation correlation results in ≤100 ka ages. The morphometric approach is supported by U/Pb and U/He chronology: preliminary results of zircon dating indicate ages ranging between 200(250) and 30 ka. The youngest ages of the data set obtained both from lavas and pumiceous pyroclastics argue for a more or less coeval effusive and explosive volcanism. Based also on volcanological data, we propose vulcanian eruptions and explosive dome collapses especially toward the end of volcanic activity. Moreover, radiometric chronology suggests that, possibly subsequently to the peripheral domes, a central lava dome complex built up ≤100 ka ago. This dome complex, exhibiting even more violent, up to sub-plinian explosions, emplaced pumiceous pyroclastic flow and fall deposits as far as 17 km. We propose that the explosive activity produced caldera-forming eruptions as well, creating a half-caldera. This caldera rim is manifested by the asymmetric morphology of the central edifice: the present-day elevated ridge of Ciomadul Mare (Nagy Csomád), encompassing the twin craters of Mohoş (Mohos) peat bog and Sf. Ana (Szent [St.] Anna). These latter craters may have been formed subsequently, ca. ~100-30 ka ago, after the caldera formation. Drilling of lacustrine sediments in the St. Anna crater shows that beneath the Holocene gyttja several meters of Late Pleistocene

  6. Anomalous zones in Gulf Coast Salt domes with special reference to Big Hill, TX, and Weeks Island, LA

    SciTech Connect

    Neal, J.T.; Magorian, T.R.; Thoms, R.L.; Autin, W.J.; McCulloh, R.P.; Denzler, S.; Byrne, K.O.

    1993-07-01

    Anomalous features in Gulf Coast Salt domes exhibit deviations from normally pure salt and vary widely in form from one dome to the next, ranging considerably in length and width. They have affected both conventional and solution mining in several ways. Gas outbursts, insolubles, and potash (especially carnallite) have led to the breakage of tubing in a number of caverns, and caused irregular shapes of many caverns through preferential leaching. Such anomalous features essentially have limited the lateral extent of conventional mining at several salt mines, and led to accidents and even the closing of several other mines. Such anomalous features, are often aligned in anomalous zones, and appear to be related to diapiric processes of salt dome development. Evidence indicates that anomalous zones are found between salt spines, where the differential salt intrusion accumulates other materials: Anhydrite bands which are relatively strong, and other, weaker impurities. Shear zones and fault displacement detected at Big Hill and Weeks Island domes have not yet had any known adverse impacts on SPR oil storage, but new caverns at these sites conceivably may encounter some potentially adverse conditions. Seismic reflection profiles at Big Hill dome have shown numerous fractures and faults in the caprock, and verified the earlier recognition of a major shear zone transecting the entire salt stock and forming a graben in the overlying caprock. Casing that is placed in such zones can be at risk. Knowledge of these zones should create awareness of possible effects rather than preclude the future emplacement of caverns. To the extent possible, major anomalous zones and salt stock boundaries should be avoided. Shear zones along overhangs may be particularly hazardous, and otherwise unknown valleys in the top of salt may occur along shear zones. These zones often can be mapped geophysically, especially with high-resolution seismic techniques.

  7. Final report on decommissioning of wells, boreholes, and tiltmeter sites, Gulf Coast Interior Salt Domes of Louisiana

    SciTech Connect

    Not Available

    1989-07-01

    In the late 1970s, test holes were drilled in northern Louisiana in the vicinity of Vacherie and Rayburn`s Salt Domes as part of the Department of Energy`s (DOE) National Waste Terminal Storage (NWTS) (rename the Civilian Radioactive Waste Management (CRWM)) program. The purpose of the program was to evaluate the suitability of salt domes for long term storage or disposal of high-level nuclear waste. The Institute for Environmental Studies at Louisiana State University (IES/LSU) and Law Engineering Testing Company (LETCo) of Marietta, Georgia performed the initial field studies. In 1982, DOE awarded a contract to the Earth Technology Corporation (TETC) of Long Beach, California to continue the Gulf Coast Salt Dome studies. In 1986, DOE deferred salt domes from further consideration as repository sites. This report describes test well plugging and site abandonment activities performed by SWEC in accordance with Activity Plan (AP) 1--3, Well Plugging and Site Restoration of Work Sites in Louisiana. The objective of the work outlined in this AP was to return test sites to as near original condition as possible by plugging boreholes, removing equipment, regrading, and seeding. Appendices to this report contain forms required by State of Louisiana, used by SWEC to document decommissioning activities, and pertinent documentation related to lease/access agreements.

  8. An assessment of hydrothermal alteration in the Santiaguito lava dome complex, Guatemala: implications for dome collapse hazards

    USGS Publications Warehouse

    Ball, Jessica L.; Calder, Eliza S.; Hubbard, Bernard E.; Bernstein, Marc L.

    2013-01-01

    A combination of field mapping, geochemistry, and remote sensing methods has been employed to determine the extent of hydrothermal alteration and assess the potential for failure at the Santiaguito lava dome complex, Guatemala. The 90-year-old complex of four lava domes has only experienced relatively small and infrequent dome collapses in the past, which were associated with lava extrusion. However, existing evidence of an active hydrothermal system coupled with intense seasonal precipitation also presents ideal conditions for instability related to weakened clay-rich edifice rocks. Mapping of the Santiaguito dome complex identified structural features related to dome growth dynamics, potential areas of weakness related to erosion, and locations of fumarole fields. X-ray diffraction and backscattered electron images taken with scanning electron microscopy of dacite and ash samples collected from around fumaroles revealed only minor clay films, and little evidence of alteration. Mineral mapping using ASTER and Hyperion satellite images, however, suggest low-temperature (<150 °C) silicic alteration on erosional surfaces of the domes, but not the type of pervasive acid-sulfate alteration implicated in collapses of other altered edifices. To evaluate the possibility of internal alteration, we re-examined existing aqueous geochemical data from dome-fed hot springs. The data indicate significant water–rock interaction, but the Na–Mg–K geoindicator suggests only a short water residence time, and δ18O/δD ratios show only minor shifts from the meteoric water line with little precipitation of secondary (alteration) minerals. Based on available data, hydrothermal alteration on the dome complex appears to be restricted to surficial deposits of hydrous silica, but the study has highlighted, importantly, that the 1902 eruption crater headwall of Santa María does show more advanced argillic alteration. We also cannot rule out the possibility of advanced alteration

  9. Dome-type: a distinctive variant of colonic adenocarcinoma.

    PubMed

    Puppa, Giacomo; Molaro, Mariella

    2012-01-01

    Introduction. Ten cases of dome-type adenocarcinoma of the colon have been reported so far. Most of them were presented as early lesions, with endoscopic and microscopic distinguishing features. Methods and Results. A raised plaque was removed from the right colon during colonoscopy in a 56-year-old man. Histopathological examination showed a cancerized adenoma invading the submucosa with several typical features of dome-type adenocarcinoma, in particular the associated prominent lymphoid tissue. Immunohistochemistry showed retention of the mismatch repair proteins MLH-1, MSH-2, MLH-6, and PMS-2. Conclusion. We report an additional case of dome-type adenocarcinoma of the colon as an early, low-risk, and microsatellite stable tumor, indicating that this particular histotype may deserve specific consideration for both classification and management.

  10. Radar scattering properties of pancakelike domes on Venus

    NASA Technical Reports Server (NTRS)

    Ford, P. G.; Pettengill, G. H.

    1992-01-01

    Magellan radar images have disclosed the presence of a large number of almost perfectly circular domes, presumably of volcanic origin, in many regions of Venus several with diameters of 30 km or more. Their high degree of symmetry has permitted measurements of their shape, as determined by the Magellan altimeter to be compared with models of dome production from the eruption of high-viscosity magmas. In this work, we examine in detail the radar images of domes in Rusalka Planitia (2.8 deg S, 150.9 deg E) and Tinatin Planitia (12.2 deg N, 7.5 deg E), selected for their circular symmetry and apparent absence of modification due to large-scale slumping or tectonic rifting.

  11. Lunar mare domes - Classification and modes of origin

    NASA Technical Reports Server (NTRS)

    Head, J. W.; Gifford, A.

    1980-01-01

    In this paper, lunar mare domes (LMDs) are classified according to morphologic and morphometric (primarily diameter) characteristics, and consideration is given to their origin and role in lunar surface processes. In general, they occur either as low, flat, circular structures with convex shapes, slopes less than about 5 deg, and display summit craters, or as irregular structures often adjacent to highland regions and rarely containing summit craters. It is found that LMDs originate through extrusion of lavas through vents to produce low lava shields, or through flooding and draping of preexisting topography to produce kipukas and irregular domes. Smooth, vent-related mare domes range from about 3-17 km in diameter and up to several hundred meters in elevation; they are similar in morphology to small terrestrial lava shields.

  12. Domes on Europa: The Role of Thermally Induced Compositional Diapirism

    NASA Technical Reports Server (NTRS)

    Pappalardo, R. T.; Barr, A.C.

    2004-01-01

    The surface of Europa is peppered by topographic domes, interpreted as sites of intrusion and extrusion. Diapirism is consistent with dome morphology, but thermal buoyancy alone cannot produce sufficient driving pressures to create the observed dome elevations. Instead, we suggest that diapirs may initiate by thermal convection that induces compositional segregation within Europa's ice shell. This double-diffusive convection scenario allows sufficient buoyancy for icy plumes to create the observed surface topography, if the ice shell has a very small effective elastic thickness (approximately 0.1 to 0.5 km) and contains low-eutectic-point impurities at the percent level. Thermal buoyancy, compositional buoyancy and double-diffusive convection are discussed.

  13. Stresses in dome-shaped shells of revolution with discontinuities at the apex

    NASA Technical Reports Server (NTRS)

    Chen, C. H.; Yu, J. C. M.; Shaw, W. A.

    1974-01-01

    Asymptotic solutions of Novozhilov's equations of shells of revolution are derived for axisymmetric and first harmonic loadings. The solutions obtained are valid throughout the shallow and nonshallow regions. Stresses in dome shaped shells of revolution with a discontinuity in the form of a circular hole, a circular rigid insert, or a nozzle at the apex have been investigated. Numerical results are obtained for spheres, ellipsoids, and paraboloids, containing a discontinuity under a internal pressure and moment. Curves depicting stress distributions are given. The influence of three types of discontinuity on the stresses of the shells is also given.

  14. Exploring Learning through Audience Interaction in Virtual Reality Dome Theaters

    NASA Astrophysics Data System (ADS)

    Apostolellis, Panagiotis; Daradoumis, Thanasis

    Informal learning in public spaces like museums, science centers and planetariums is increasingly popular during the last years. Recent advancements in large-scale displays allowed contemporary technology-enhanced museums to get equipped with digital domes, some with real-time capabilities like Virtual Reality systems. By conducting extensive literature review we have come to the conclusion that little to no research has been carried out on the leaning outcomes that the combination of VR and audience interaction can provide in the immersive environments of dome theaters. Thus, we propose that audience collaboration in immersive virtual reality environments presents a promising approach to support effective learning in groups of school aged children.

  15. Analysis and test of low profile aluminum aerospace tank dome

    NASA Technical Reports Server (NTRS)

    Ahmed, R.; Wilhelm, J. M.

    1993-01-01

    In order to increase the structural performance of cryogenic tanks, the aerospace industry is beginning to employ low-profile bulkheads in new generation launch vehicle designs. This report details the analysis and test of one such dome made from 2219 aluminum. Such domes have two potential failure modes under internal pressure, general tensile failure and hoop compression buckling (in regions near the equator). The test determined the buckling load and ultimate tensile load of the hardware and showed that both compared well with the analysis predictions. This effort was conducted under the auspices of NASA and the General Dynamics Cryogenic Tank Technology Program (CTTP).

  16. FLAMMABLE GAS DIFFUSION THROUGH SINGLE SHELL TANK (SST) DOMES

    SciTech Connect

    MEACHAM, J.E.

    2003-11-10

    This report quantified potential hydrogen diffusion through Hanford Site Single-Shell tank (SST) domes if the SSTs were hypothetically sealed airtight. Results showed that diffusion would keep headspace flammable gas concentrations below the lower flammability limit in the 241-AX and 241-SX SST. The purpose of this document is to quantify the amount of hydrogen that could diffuse through the domes of the SSTs if they were hypothetically sealed airtight. Diffusion is assumed to be the only mechanism available to reduce flammable gas concentrations. The scope of this report is limited to the 149 SSTs.

  17. Evidence for Neoarchaean extensional faults in the Vredefort Dome, South Africa.

    NASA Astrophysics Data System (ADS)

    mashabela, sello

    2013-04-01

    The Vredefort Dome is an approximately 80-90 km wide impact structure, situated 120 km southwest of Johannesburg in South Africa. The dome is a preserved centrally uplifted region of an ancient 250-300 km wide multi-ringed crater that formed at 2.02 Ga. The ancient crater underwent 5-10 km of erosion to expose the Vredefort Dome, allowing for unique study of the deeper levels of the impact crater. The Vredefort Dome is composed of a 40 km wide core, bounded by a 20-25 km wide collar. The core is wholly composed of Mesoarchaean basement gneiss (ca. 3.1 Ga), and the collar is made up of mid-amphibolite to lower greenschist facies supracrustal rocks (ca. 3.0-2.2 Ga). Fault development in the collar has largely been attributed to the impact, except for two fault systems. The two exceptions have been described as pre-impact faults, with apparent strike-slip displacements up to 3 km. It is the focus of this study to distinguish pre-impact structures from impact-related structures. Ortho-photographs, satellite images, and field mapping have shown that pre-impact faults were listric in character, and associated with second order accommodation faults. The main fault is associated with a 20 m wide zone of pseudotachylitic breccia. Most of the pseudotachylitic breccia in the dome has been attributed to the impact, so these faults were possibly associated with earlier pseudotachylite generation. Cleavage associated with the listric faults is displaced by impact-related faults, confirming the existence of two deformation events in the dome. The geometry of the listric faults is similar to those observed in the West Wits Line and West Rand goldfields (55 km north of Vredefort Dome), which have been modelled by Manzi et al. (2012, a, b; submitted) using 3D seismic techniques. The authors attribute the development of listric faults (or a rift-like system of faults) to crustal extension that took place during deposition of Klipriviersberg Group lavas and Platberg Group (2709

  18. Giant magnetostriction in Tb-doped Fe{sub 83}Ga{sub 17} melt-spun ribbons

    SciTech Connect

    Wu, Wei; Liu, Jinghua; Jiang, Chengbao; Xu, Huibin

    2013-12-23

    Giant magnetostriction is achieved in lightly Tb-doped Fe{sub 83}Ga{sub 17} melt-spun ribbons. The average perpendicular magnetostriction λ{sub ⊥} is −886 ppm along the melt-spun ribbon direction in the Fe{sub 82.89}Ga{sub 16.88}Tb{sub 0.23} alloy and the calculated parallel magnetostriction λ{sub ‖‖} is 1772 ppm. These values are more than four times as large as those found in binary Fe{sub 83}Ga{sub 17}. The enhanced magnetostriction is attributed to a small amount of Tb entering solution in the A2 matrix phase during rapid solidification. The strong localized magnetocrystalline anisotropy of terbium is thought to cause the giant magnetostriction.

  19. Shapes of Venusian 'pancake' domes imply episodic emplacement and silicic composition

    NASA Astrophysics Data System (ADS)

    Fink, J. H.; Bridges, N. T.; Grimm, R. E.

    1993-02-01

    The main evidence available for constraining the composition of the large circular 'pancake' domes on Venus is their gross morphology. Laboratory simulations using polyethylene glycol show that the height to diameter (aspect) ratios of domes of a given total volume depend critically on whether their extrusion was continuous or episodic, with more episodes leading to greater cooling and taller domes. Thus without observations of their emplacement, the compositions of Venusian domes cannot be uniquely constrained by their morphology. However, by considering a population of 51 Venusian domes to represent a sampling of many stages during the growth of domes with comparable histories, and by plotting aspect ratio versus total volume, we find that the shapes of the domes are most consistent with episodic emplacement. On Earth this mode of dome growth is found almost exclusively in lavas of dacite to rhyolite composition, strengthening earlier inferences about the presence of evolved magmas on Venus.

  20. Lunar Intrusive Domes on the Floor of Grimaldi and Near Aristillus

    NASA Astrophysics Data System (ADS)

    Wöhler, C.; Lena, R.; Pau, K. C.

    2010-03-01

    In this contribution we examine two large lunar domes of probably intrusive origin. The morphometric properties of the domes are derived, and geophysical parameters (intrusion depth, magma pressure) are estimated based on modelling.

  1. Shapes of Venusian 'pancake' domes imply episodic emplacement and silicic composition

    NASA Technical Reports Server (NTRS)

    Fink, Jonathan H.; Bridges, Nathan T.; Grimm, Robert E.

    1993-01-01

    The main evidence available for constraining the composition of the large circular 'pancake' domes on Venus is their gross morphology. Laboratory simulations using polyethylene glycol show that the height to diameter (aspect) ratios of domes of a given total volume depend critically on whether their extrusion was continuous or episodic, with more episodes leading to greater cooling and taller domes. Thus without observations of their emplacement, the compositions of Venusian domes cannot be uniquely constrained by their morphology. However, by considering a population of 51 Venusian domes to represent a sampling of many stages during the growth of domes with comparable histories, and by plotting aspect ratio versus total volume, we find that the shapes of the domes are most consistent with episodic emplacement. On Earth this mode of dome growth is found almost exclusively in lavas of dacite to rhyolite composition, strengthening earlier inferences about the presence of evolved magmas on Venus.

  2. Giant magnetoimpedance effect in melt-spun Co-based amorphous ribbons and wires with induced magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Tiberto, P.; Vinai, F.; Rampado, O.; Chiriac, H.; Ovari, T. A.

    1999-05-01

    GMI in Co 68.25Fe 4.5Si 12.25B 15 melt-spun amorphous wires and ribbons has been studied. Selected samples have been submitted to DC Joule-heating to induce circular and transverse magnetic anisotropy. Hysteresis loops have been measured using a fluxmetric technique. The results were interpreted in terms of circumferential and transverse permeability correlated with the magnetic domain structure.

  3. Tailoring Wettability Through the Surface Modification of Electro-spun Polymers by Plasma and Sol-gel Treatments

    DTIC Science & Technology

    2014-11-01

    surface to be superhydrophobic or oleophobic are low surface energies and minimal contact between the liquid and surface, which is often created by...sol-gel reactions with low surface energy alkyl siloxanes, and plasma polymerization was attempted. Water contact angles of spun fibre mats were...coatings resulted in water contact angles > 150o and very small tilt angles. Argon plasma treatment of the fibres resulted in water drops completely

  4. Topaz rhyolites of Nathrop, Colorado: Lava domes or rheomorphic flows?

    NASA Astrophysics Data System (ADS)

    Hernandez, B. M.; Panter, K. S.; Van Der Voo, R.

    2013-12-01

    Deposits of topaz-bearing rhyolite at Ruby and Sugarloaf Mountains in central Colorado are considered to be remnants of lava domes. The deposits are part of the Late Eocene-Oligocene Central Colorado Volcanic Field [1] that lies along the eastern margin of the Arkansas Graben of the Rio Grande Rift. Topaz-bearing rhyolite lava domes and flows have been identified elsewhere in Colorado and the western U.S., but an assortment of geomorphological, lithostratigraphical, and textural features of Ruby and Sugarloaf Mountains call into question their strict classification as such. Alternatively, the lava flows may be interpreted as rheomorphic ignimbrites. The volcanic deposits encompass a sequence of steeply (~70°) west-dipping units that form two N-S elongated edifices ~0.5 km long and a few hundred meters high. Their common lithostratigraphy from bottom to top is tuff breccia, vitrophyre, and flow-banded rhyolite. The tuff breccia includes large (up to ~1 m) pumice blocks and lithics that vary from nearly absent to moderately abundant (10-20%). At Sugarloaf lithics include rare cobble-sized clasts of granite, but the majority consists of flow-banded rhyolite. The tuff breccia grades normally upward into the vitrophyre with increased welding and a eutaxitic fabric defined by fiamme with increasing aspect ratios. Lithics are abundant in the vitrophyre at Sugarloaf but are rare or absent in the vitrophyre at Ruby Mountain. The transition from the vitrophyre to the flow-banded rhyolite is abrupt (<1 m) at both locations, though the lower rhyolite is less competent. The flow-banded rhyolite at Sugarloaf is crystal-rich (up to 50%), containing plagioclase, sanidine, smoky quartz, and biotite, while at Ruby the rhyolite is relatively crystal poor (2-3%) and biotite is absent. Pumiceous zones and lithophysae occur within the rhyolite at both locations. Zones of auto-brecciation are often associated with convoluted flow banding, especially along a vertical contact with

  5. 14. PHOTOCOPY OF PHOTOGRAPH: DOMED CEILING OF AUDITORIUM, Date unknown. ...

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

    14. PHOTOCOPY OF PHOTOGRAPH: DOMED CEILING OF AUDITORIUM, Date unknown. from FOURTH CHURCH OF CHRIST, SCIENTIST ARCHIVE (used with permission) E. S. Cheney and R. B. Bird, Photographers, Cheney Photo Adv. Co., Oakland, California. - Fourth Church of Christ, Scientist, 1330 Lakeshore Avenue, Oakland, Alameda County, CA

  6. Two types of superconducting domes in unconventional superconductors

    NASA Astrophysics Data System (ADS)

    Das, Tanmoy; Panagopoulos, Christos

    2016-10-01

    Uncovering the origin of unconventional superconductivity is often plagued by the overwhelming material diversity with varying normal and superconducting (SC) properties. In this article, we deliver a comprehensive study of the SC properties and phase diagrams using multiple tunings (such as disorder, pressure or magnetic field in addition to doping and vice versa) across several families of unconventional superconductors, including the copper-oxides, heavy-fermions, organics and the recently discovered iron-pnictides, iron-chalcogenides, and oxybismuthides. We discover that all these families often possess two types of SC domes, with lower and higher SC transition temperatures T c, both unconventional but with distinct SC and normal states properties. The lower T c dome arises with or without a quantum critical point (QCP), and not always associated with a non-Fermi liquid (NFL) background. On the contrary, the higher-T c dome clearly stems from a NFL or strange metal phase, without an apparent intervening phase transition or a QCP. The two domes appear either fully separated in the phase diagram, or merged into one, or arise independently owing to their respective normal state characteristics. Our findings suggest that a QCP-related mechanism is an unlikely scenario for the NFL phase in these materials, and thereby narrows the possibility towards short-range fluctuations of various degrees of freedom in the momentum and frequency space. We also find that NFL physics may be a generic route to higher-T c superconductivity.

  7. Power production with two-phase expansion through vapor dome

    SciTech Connect

    Amend, W.E.; Toner, S.J.

    1984-08-07

    In a system wherein a fluid exhibits a regressive vapor dome in a T-S diagram, the following are provided: a two-phase nozzle receiving the fluid in pressurized and heated liquid state and expanding the received liquid into saturated or superheated vapor state, and apparatus receiving the saturated or superheated vapor to convert the kinetic energy thereof into power.

  8. Completely open-foldable domes remaining cool in sunshine

    NASA Astrophysics Data System (ADS)

    Hammerschlag, Robert H.; Deelen, Sander; Hoogendoorn, Pieter W.; Kommers, Johannes N. M.; Sonner, Thomas; Simoes, Roberto; Grassin, Olivier; Fischer, Andreas; Visser, Simon; Thewissen, Kristof

    2016-07-01

    These open-foldable very light-weight domes, based on very strong textile membranes highly tensioned between steel bows, are designed for bad-weather protection and maintenance of instruments for astronomical, meteorological and civil-engineering measurements and have extremely high wind stability. The domes of the GREGOR telescope and the Dutch Open Telescope are the two existing prototypes. Improvements were developed with all parts light-colored to remain cool in solar light. The new specially made connection parts (eyes) between the textile parts are made from white-colored PETP, a very strong and UV-stable synthetic, and have a better geometrical shape giving higher stability. The rubber seal tubes on top of the dome were of black-colored chloride rubber CR (neoprene), strong and UV stable, but very warm in sunlight. New UV-stable EPDM rubber tubes were produced in natural light color. To get this rubber stiff enough to give good sealing, a black-colored stiff EPDM rubber is put inside the light-colored one. Tests were performed and the forces necessary for compression of the rubber tubes were measured. An inside black tube with a circa 1.3 times larger compression force than the original black tubes was applied. The assembling of the black tubes into the light-colored tubes was successfully applied at the DOT and GREGOR domes.

  9. 19. View of satcom communication dome with TR radome in ...

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

    19. View of satcom communication dome with TR radome in background right. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  10. Nafion electro-spun reinforced membranes for polymer electrolyte fuel cell.

    PubMed

    Carbone, Alessandra; Saccà, Ada; Busacca, Concetta; Frontera, Patrizia; Antonucci, Pier Luigi; Passalacqua, Enza

    2011-10-01

    The introduction of different reinforcement materials (yarns, fibrils, etc) into the membranes has been investigated with the aim of maintaining adequate membrane properties in terms of mechanical strength, good chemical stability, low swelling at critical temperatures and a stable electrochemical performance in PEFC. An innovative technique for the development of membranes is based on polymeric films containing polymeric nanofibres obtained through electrospinning. The electrospinning of Nafion blends with polyvinylpirrolidone (PVP) and polystyrene (PS) was investigated in this work. In particular, the morphology and diameter of electrospun fibres as a function of the electrospinning parameters and solution preparation have been studied and in both cases, a critical concentration of blend solution was found. Beaded fibres were obtained above such a concentration and, below it, only fibre mats were observed. Reinforced Nafion-based membranes were realised by using the obtained spun films. Preliminary proton conductivity and fuel cell results have shown the capability of operating in a fuel cell environment with a slightly higher performance than pure Nafion but having an improved stability at high temperatures.

  11. Magnetocaloric Properties Response in High-Speed Melt-Spun La-Ce-Fe-Si Ribbons

    NASA Astrophysics Data System (ADS)

    Hou, Xueling; Han, Ning; Xue, Yun; Lu, Qianqian; Wang, Xiaochen; Phan, Manh-Huong

    2016-10-01

    The structure and magnetocaloric properties of La-Ce-Fe-Si alloys have been studied. The samples were prepared by melt spinning, the surface speed of the Cu wheel being 55 m/s. The as-spun ribbons were subsequently annealed at 1273 K for different times (10 min-1 h) and then quenched to room temperature. When the annealing time was 20 min, on a 1.5-T applied magnetic field, the maximum magnetic entropy change (Δ S M) of the ribbons reached values of 33.8 J/kg K at the Curie temperature of T C ˜ 182 K. When the annealing time was longer than 20 min, the maximum magnetic entropy change (|Δ S M,Max|) tended to decrease while the T C remained almost unchanged. In the annealing process, La/Ce located at grain boundaries was easily oxidized on the ribbon surface. The presence of large grain sizes and La2O3 or LaO were shown to degrade the magnetocaloric properties. On the other hand, the substitution of Ce for La improved the magnetocaloric effect of La-Fe-Si compounds, which is of practical importance for magnetic refrigeration.

  12. High performance electrochemical and electrothermal artificial muscles from twist-spun carbon nanotube yarn

    NASA Astrophysics Data System (ADS)

    Lee, Jae Ah; Baughman, Ray H.; Kim, Seon Jeong

    2015-04-01

    High performance torsional and tensile artificial muscles are described, which utilize thermally- or electrochemically-induced volume changes of twist-spun, guest-filled, carbon nanotube (CNT) yarns. These yarns were prepared by incorporating twist in carbon nanotube sheets drawn from spinnable CNT forests. Inserting high twist into the CNT yarn results in yarn coiling, which can dramatically amplify tensile stroke and work capabilities compared with that for the non-coiled twisted yarn. When electrochemically driven in a liquid electrolyte, these artificial muscles can generate a torsional rotation per muscle length that is over 1000 times higher than for previously reported torsional muscles. All-solid-state torsional electrochemical yarn muscles have provided a large torsional muscle stroke (53° per mm of yarn length) and a tensile stroke of up to 1.3% when lifting loads that are ~25 times heavier than can be lifted by the same diameter human skeletal muscle. Over a million torsional and tensile actuation cycles have been demonstrated for thermally powered CNT hybrid yarns muscles filled with paraffin wax, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. At lower actuation rates, these thermally powered muscles provide tensile strokes of over 10%.

  13. Tough and catalytically active hybrid biofibers wet-spun from nanochitin hydrogels.

    PubMed

    Das, Paramita; Heuser, Thomas; Wolf, Andrea; Zhu, Baolei; Demco, Dan Eugen; Ifuku, Shinsuke; Walther, Andreas

    2012-12-10

    Sustainable alternatives for high-performance and functional materials based on renewable resources are intensely needed as future alternatives for present-day, fossil-based materials. Nanochitin represents an emerging class of highly crystalline bionanoparticles with high intrinsic mechanical properties and the ability for conjugation into functional materials owing to reactive amine and hydroxyl groups. Herein we demonstrate that hydrogels containing surface-deacetylated chitin nanofibrils of micrometer length and average diameters of 9 nm, as imaged by cryogenic transmission electron microscopy, can be wet-spun into macrofibers via extrusion in a coagulation bath, a simple low energy and large-scale processing route. The resulting biofibers display attractive mechanical properties with a large plastic region of about 12% in strain, in which frictional sliding of nanofibrils allows dissipation of fracture energy and enables a high work-of-fracture of near 10 MJ/m3. We further show how to add functionality to these macrofibers by exploiting the amine functions of the surface chitosan groups to host catalytically active noble metal nanoparticles, furnishing biobased, renewable catalytic hybrids. These inorganic/organic macrofibers can be used repeatedly for fast catalytic reductions of model compounds without loss of activity, rendering the concept of hybridized chitin materials interesting as novel bioderived supports for nanoparticle catalysts.

  14. Characterisation of melt spun Ni-Ti shape memory Ribbons' microstructure

    NASA Astrophysics Data System (ADS)

    Mehrabi, Kambiz; Brunčko, Mihael; Kneissl, Albert C.; Čolič, Miodrag; Stamenković, Dragoslav; Ferčec, Janko; Anžel, Ivan; Rudolf, Rebeka

    2012-06-01

    NiTi alloys are the most technologically important medical Shape Memory Alloys in a wide range of applications used in Orthopaedics, Neurology, Cardiology and interventional Radiology as guide-wires, self-expandable stents, stent grafts, inferior vena cava filters and clinical instruments. This paper discusses the use of rapid solidification by the melt spinning method for the preparation of thin NiTi ribbons for medical uses. Generally, the application of rapid solidification via melt-spinning can change the microstructure drastically, which improves ductility and shape memory characteristics and leads to samples with small dimensions. As the increase in the wheel speed led to a reduced ribbon thickness, the cooling rate increased and, therefore, the martensitic substructure became finer. Furthermore, no transition from the crystalline phase to the amorphous phase was obtained by increasing the cooling rate, even at a wheel speed of 30 m/s. Specimens for our metallographic investigation were cut from the longitudinal cross sections of melt-spun ribbons. Conventional TEM studies were carried out with an acceleration voltage of 120 kV. Additionally, the chemical composition of the samples was examined with a TEM equipped with an EDX analyser. The crystallographic structure was determined using Bragg-Brentano x-ray diffraction with Cu-Kα radiation at room temperature.

  15. Physio-chemical and antibacterial characteristics of pressure spun nylon nanofibres embedded with functional silver nanoparticles.

    PubMed

    Xu, Z; Mahalingam, S; Rohn, J L; Ren, G; Edirisinghe, M

    2015-11-01

    A novel and facile approach to prepare hybrid nanoparticle embedded polymer nanofibers using pressurised gyration is presented. Silver nanoparticles and nylon polymer were used in this work. The polymer solution's physical properties, rotating speed and the working pressure had a significant influence on the fibre diameter and the morphology. Fibres in the range of 60-500nm were spun using 10wt.%, 15wt.% and 20wt.% nylon solutions and these bead-free fibres were processed under 0.2MPa and 0.3MPa working pressure and a rotational speed of 36,000rpm. 1-4wt.% of Ag was added to these nylon solutions and in the case of wt.% fibres in the range 50-150nm were prepared using the same conditions of pressurised gyration. Successful incorporation of the Ag nanoparticles in nylon nanofibres was confirmed by using a combination of advanced microscopical techniques and Raman spectrometry was used to study the bonding characteristics of nylon and the Ag nanoparticles. Inductively coupled plasma mass spectroscopy showed a substantial concentration of Ag ions in the nylon fibre matrix which is essential for producing effective antibacterial properties. Antibacterial activity of the Ag-loaded nanofibres shows higher efficacy than nylon nanofibres for Gram-negative Escherichia coli and Pseudomonas aeruginosa microorganisms, and both Ag nanoparticles and the Ag ions were found to be the reason for enhanced cell death in the bacterial solutions.

  16. Local structure in magnetostrictive melt-spun Fe80Ga20 alloys

    NASA Astrophysics Data System (ADS)

    Pascarelli, S.; Ruffoni, M. P.; Sato Turtelli, R.; Kubel, F.; Grössinger, R.

    2008-05-01

    We perform a detailed investigation of the local atomic structure in highly magnetostrictive α-FeGa melt-spun ribbons. By using extended x-ray absorption fine structure (EXAFS) analysis at the Fe and GaK edges coupled to x-ray diffraction (XRD) and to ab initio full multiple scattering calculations of the x-ray absorption near edge structure (XANES), we test for the presence of different local defect structures proposed in literature as being responsible for the large magnetostriction in these alloys. XRD shows that the ribbons crystallize in the A2 phase. Invisible by XRD, the presence of small Ga clusters is excluded by both EXAFS and XANES since no first shell Ga-Ga bonds are detected. However, EXAFS analysis of the second coordination shell around Ga clearly provides evidence for the presence of one highly strained (+4%) Ga-Ga pair and five Ga-Fe pairs, among the six crystallographically equivalent ⟨001⟩ atomic pairs. This conclusion supports recent total energy calculations that assign the large magnetostriction in these alloys to the strain caused by the rotation of the magnetization in the vicinity of such defects.

  17. Hard magnetic properties of melt-spun Mn-Al-C alloys

    NASA Astrophysics Data System (ADS)

    Pasko, A.; Mazaleyrat, F.; LoBue, M.; Fazakas, E.; Varga, L. K.

    2013-01-01

    Structural and magnetic characterization of Mnx-yAl100-x-yC2y (x = {50, 55}; y = {0, 1}) melt­spun ribbons is reported. To obtain the metastable ferromagnetic τ­phase, rapidly solidified alloys were annealed either in a vacuum furnace at 823 K or directly in the vibrating sample magnetometer under applied magnetic field. Optimal magnetic properties were demonstrated by Mn54Al44C2 samples proved to be single­phase with a coercivity of 0.19 T measured in both cases. For this composition the structural ɛ→τ phase transformation has been magnetically detected at 786 K, Curie temperature of τ­phase (Tc = 592 K, Tp = 610 K) has been determined using mean field approximations in ferromagnetic and paramagnetic regions. Rietveld refinement of X­ray diffraction spectra was employed to analyse the phase constitution of annealed alloys, lattice parameters as a function of chemical composition and mean grain size for the phases involved.

  18. Structure and magnetic properties of amorphous Fe-(Zr,Nb)-B melt spun alloys

    NASA Astrophysics Data System (ADS)

    Zamora, J.; Betancourt, I.

    2017-04-01

    In this work, we report the structure and magnetic behavior of an amorphous Fe81Zr5Nb4B10 melt-spun alloy. The radial distribution function (RDF) afforded the resolution of the nearest-neighbor configuration on the basis of the atom-pair distance information, for which the positions of each peak indicated the atom-to-atom separation involved for short-range ordering. The first peaks of RDF were attributed to the distances of B-B, Fe-Fe and Zr-Nb atomic pairs, indicating a glassy structure equivalent to a distorted bcc-Fe cluster. From magnetic measurements, a magnetic moment of 0.65 Bohr magneton per Fe atom was established, together with a Curie temperature of 334 K and an initial ac permeability of 550 for frequencies as high as 250 kHz. In addition, the magnetocaloric effect, quantified from isothermal magnetization measurements through the magnetic entropy variation, reached a maximum of 2.0 J/kg K for a magnetic field change of 2.0 T.

  19. High-coercivity samarium-iron-nitrogen from nitriding melt-spun ribbons

    SciTech Connect

    Pinkerton, F.E.; Fuerst, C.D. )

    1993-04-01

    Melt spinning has proven to be an excellent technique for magnetic hardening of a variety of permanent magnet materials, especially Nd-Fe-B. Recently, a new permanent magnet material has been discovered by nitriding the compound Sm[sub 2]Fe[sub 17] to obtain Sm[sub 2]Fe[sub 17]N[sub x]. The authors have obtained magnetically hard Sm-Fe-N ribbons with a room-temperature intrinsic coercivity H[sub ci] = 22 kOe (1.8 MA/m) by nitriding melt-spun Sm-Fe precursor ribbons. Best results were obtained by grinding the ribbons to a <25 [mu]m powder, then heat treating the powder in vacuum for 1 h at 700 C prior to nitriding in N[sub 2] gas at 450 to 480 C. X-ray diffraction shows that the primary phase is TbCu[sub 7]-type Sm[sub 2]Fe[sub 17]N[sub x], a disordered hexagonal modification of the rhombohedral Sm[sub 2]Fe[sub 17] phase.

  20. Enhancement of the mechanical properties of directly spun CNT fibers by chemical treatment.

    PubMed

    Boncel, Slawomir; Sundaram, Rajyashree M; Windle, Alan H; Koziol, Krzysztof K K

    2011-12-27

    Translating the remarkable mechanical properties of individual carbon nanotubes to macroscopic assemblies presents a unique challenge in maximizing the potential of these remarkable entities for new materials. Infinitely long individual nanotubes would represent the ideal molecular building blocks; however, in the case of length-limited nanotubes, typically in the range of micro- and millimeters, an alternative strategy could be based on the improvement of the mechanical coherency between bundles assembling the macroscopic materials, like fibers or films. Here, we present a method to enhance the mechanical performance of fibers continuously spun from a CVD reactor, by a postproduction processing methodology utilizing a chemical agent aided by UV irradiation. The treatment results in an increase of 100% in specific strength and 300% in toughness of the fibers with strength values rocketing to as high as 3.5 GPa SG(-1). An attempt has been made to explore the nature of the chemical modifications introduced in the fiber and the consequential effects on its properties.

  1. Effect of the co-spun anode functional layer on the performance of the direct-methane microtubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Meng, Xiuxia; Gong, Xun; Yin, Yimei; Yang, Naitao; Tan, Xiaoyao; Ma, Zi-Feng

    2014-02-01

    NiO-YSZ/porous YSZ (NiO-YSZ/p-YSZ) dual-layer hollow fibers have been fabricated by a co-spinning-sintering method, on which a dense YSZ films has been formed by a dip-coating and sintering process. A LSM-YSZ ink has been dip-coated on the dense YSZ films as cathode, while the Cu-CeO2 carbon-resistant catalyst has been impregnated in the p-YSZ layer to form double-anode supported micro tubular fuel cells (MT-SOFCs). The thickness of the Ni-YSZ layer, so called anode functional layer (AFL), is controlled from 74 μm to 13 μm by varying the spinning rates of the NiO-YSZ dopes. The maximum power density of an MT-SOFC, which is fabricated based on a thin co-spun AFL, reaches 566 mW cm-2 operated at 850 °C fed with dry methane, and is stably operated for 85 h without power declination.

  2. Hydrothermal alteration in the Baca Geothermal System, Redondo Dome, Valles Caldera, New Mexico

    NASA Astrophysics Data System (ADS)

    Hulen, Jeffrey B.; Nielson, Dennis L.

    1986-02-01

    Thermal fluids circulating in the active hydrothermal system of the resurgent Redondo dome of the Valles caldera have interacted with their diverse host rocks to produce well-zoned alteration assemblages, which not only help locate permeable fluid channels but also provide insight into the system's thermal history. The alteration shows that fluid flow has been confined principally to steeply dipping normal faults and subsidiary fractures as well as thin stratigraphic aquifers. Permeability along many of these channels has been reduced or locally eliminated by hydrothermal self-sealing. Alteration from the surface through the base of the Miocene Paliza Canyon Formation is of three distinctive types: argillic, propylitic, and phyllic. Argillic alteration forms a blanket above the deep water table in formerly permeable nonwelded tuffs. Beneath the argillic zone, pervasive propylitic alteration is weakly developed in felsic host rocks but locally intense in deep intermediate composition volcanics. Strong phyllic alteration is commonly but not invariably associated with major active thermal fluid channels. Phyllic zones yielding no fluid were clearly once permeable but now are hydrothermally sealed. High-temperature alteration phases at Baca are presently found at much lower temperatures. We suggest either that isotherms have collapsed due to gradual cooling of the system, that they have retreated without overall heat loss due to uplift of the Redondo dome, that the system has shifted laterally, or that it has contracted due to a drop in the water table. The deepest Well (B-12, 3423 m) in the dome may have penetrated through the base of the active hydrothermal system. Below a depth of 2440 m in this well, hydrothermal veining largely disappears, and the rocks resemble those developed by isochemical thermal metamorphism. The transition is reflected by temperature logs, which show a conductive thermal gradient below 2440 m. This depth may mark the dome's neutral plane

  3. Processing method and process modeling of large aperture transparent magnesium aluminate spinel domes

    NASA Astrophysics Data System (ADS)

    Yu, Jian; McWilliams, Brandon; Kilczewski, Steven; Gilde, Gary; Lidie, Ashley; Sands, James

    2009-05-01

    Polycrystalline spinel serves as an alternative to materials such as sapphire and magnesium fluoride that are currently being used in electromagnetic window applications such as missile domes, where high strength, high hardness and high transmittance in the visible and infrared spectra are required. The cubic crystal lattice of spinel imparts an isotropy to the bulk optical property, which eliminates optical distortion due to birefringence that occurs in sapphire and other non-cubic materials. The current study is to find a reliable manufacturing process to produce large magnesium aluminate spinel domes from powder consolidation efficiently. A binder-less dry ball milling process was used to deflocculate the spinel powder to increase its fluidity in an effort to ease the shape-forming. Dry ball milling time trials were conducted at several intervals to determine the appropriate level of time required to break up both the hard and soft agglomerates associated with the virgin spinel powder. The common problems encountered in dry powder shape-forming are crack growth and delamination of the green body during cold isostatic pressing (CIPing). The cracking and the delamination are due to the buildup of stress gradients on the green body that are created by the frictional force between the powder and the die wall or mold wall. To understand the stresses during the CIPing process, a finite element analysis of stresses on the green body was conducted. The simulation was used to evaluate the effect of die tooling and process characteristics on the development of stress gradients in the green body dome. Additionally, the effect of friction between the die wall and powder was examined by the simulation. It was found that by mitigating the frictional forces, cracking and delamination on the green body could be eliminated. A stepped-pressure CIPing technique was developed to reduce stress gradient build-up during CIPing. Also, oleic acid lubricant was applied to the die wall to

  4. Dome collapse eruption in Tatun Volcanic Group near metropolitan Taipei, Taiwan at ~6 kyrs

    NASA Astrophysics Data System (ADS)

    Chen, C.; Lee, T.

    2010-12-01

    The Tatun Volcanic Group (TVG) is located in the north of metropolitan Taipei, Taiwan. Over 6 million inhabitants are living in Taipei City and suburban area. Another critical issue is an international airport and two nuclear power plants are lying at the foot of the TVG. If the TGV will be re-active, the serious hazard for human lives and economies in this area will definitely occur. Understanding the youngest eruption history of the TVG will be much important for prediction the future activity of eruption. The core was collected from the Dream Lake at the eastern slop of Cising Mt.. Total 21 samples from depth 190 cm to 231.5 cm have been tested. Comparison of chemical compositions of glass and minerals in the volcanic clasts with those of lava around TVG, they clearly showed that the volcanic clasts can be correlated with the eruption of the closest Cising Mt. According to the radiocarbon (C-14) age of core sample at the depth 225 cm, the age was extrapolated around 6150 yrs ca. C-14 B.P.. Moreover, the respiratory cristobalite in the volcanic clasts were firstly identified by the identical morphology, chemical composition and Laser Raman Spectrometry (LRS). The crystalline silica was produced by vapor-phase crystallization and devitrification in the andesite lava dome and volcanic ash generated by pyroclastic flows formed by lava dome collapse in Soufriere Hills volcano, Montserrat (Baxter et al.,1999). These new evidence demonstrated that there would probably have the lava dome collapse eruptions in the TVG in the last 6 kyrs. The result in this paper also sustained that the landslide caused by the weak phreatic eruption within the last 6000 yrs in the TVG (Belousov et al., 2010). It must further be noted that an efficient program of the volcanic hazard reduction should be practiced for the metropolitan Taipei and suburban area.

  5. Using Horizontal Cosmic Muons to Investigate the Density Distribution of the Popocatepetl Volcano Lava Dome

    NASA Astrophysics Data System (ADS)

    Grabski, V.; Lemus, V.; Nuñez-Cadena, R.; Aguilar, S.; Menchaca-Rocha, A.; Fucugauchi, J. U.

    2013-05-01

    Study of volcanic inner density distributions using cosmic muons is an innovative method, which is still in stage of development[1]. The method can be used to determine the average density along the muon track, as well as the density distribution of any volume by measuring the attenuation of cosmic muon flux in it[2]. In this study we present an analysis of using the muon radiography, integrating geophysical data to determine the density distribution of the Popocatepetl volcano. Popocatepelt is a large andesitic stratovolcano built in the Trans-Mexican volcanic arc, which has been active over the past years. The recent activity includes emplacement of a lava dome, with vulcanian explosions and frequent scoria and ash emissions. The study is directed to detect any variations in the dome and magmatic conduit system in some interval of time in the volume of Popocatepetl volcano lava dome. The study forms part of a long-term project of volcanic hazard monitoring that includes the Popocatepetl and Colima volcanoes[3]. The volcanoes are being studied by conventional geophysical techniques, including aerogeophysical surveys directed to determine the internal structure and characterize source characteristics and mechanism. The detector design mostly depends on the volume size to be investigated as well as the image-taking frequency to detect dynamic density variations. In this study we present a detector prototype design and suggestions on data taking, transferring and analyzing systems. We also present the approximate cost estimation of the suggested detector and discussion on a proposal about the creation of a national network for a volcanic alarm system. References [1] eg.H. Tanaka, et al., Nucl. Instr. and Meth. A 507 (2003) 657. [2] V. Grabski et al, NIM A 585 (2008) 128-135. [3] G. Conte, J. Urrutia-Fucugauchi, et al., International Geology Review, Vol. 46, 2004, p. 210-225.

  6. Late Pleistocene zircon ages for intracaldera domes at Gölcük (Isparta, Turkey)

    NASA Astrophysics Data System (ADS)

    Schmitt, Axel K.; Danišík, Martin; Siebel, Wolfgang; Elitok, Ömer; Chang, Yu-Wei; Shen, Chuan-Chou

    2014-10-01

    Pleistocene to Quaternary volcanism in the Isparta region (SW Anatolia, Turkey) comprises potassic lavas and pyroclastic deposits, which are largely centered around Gölcük caldera. Trachytic intracaldera lava domes represent the latest eruptive event at Gölcük, and their eruption age is crucial for defining a minimum age for the preceding caldera-forming explosive eruption. Here, we present combined U-Th and (U-Th)/He zircon geochronological data for two intracaldera lava domes constraining their crystallization and eruption ages, respectively. U-Th zircon crystallization ages peak between ca. 15 and 25 ka. In rare instances U-Th zircon crystallization ages date back to ca. 59 and 136 ka. U-Th zircon crystallization ages also permit (U-Th)/He eruption ages from the same crystals to be individually corrected for uranium series decay chain disequilibrium, which is mainly due to the deficit of the intermediate daughter 230Th in zircon. Average disequilibrium-corrected (U-Th)/He zircon ages are 14.1 ± 0.5 and 12.9 ± 0.4 ka (1σ). These ages are indistinguishable within analytical uncertainties suggesting that both lavas erupted quasi simultaneously. This contradicts published K-Ar ages that suggest an extended hiatus from ca. 52 to 24 ka between intracaldera dome eruptions. Evidence for protracted zircon crystallization over several thousands of years prior to eruption indicates the presence of a long-lived magma reservoir underneath Gölcük caldera. Implications of the revised eruptive geochronology presented here include younger ages for the latest effusive eruptions at Gölcük, and potentially also a more recent explosive eruption than previously assumed.

  7. Probing permeability and microstructure: Unravelling the role of a low-permeability dome on the explosivity of Merapi (Indonesia)

    NASA Astrophysics Data System (ADS)

    Kushnir, Alexandra R. L.; Martel, Caroline; Bourdier, Jean-Louis; Heap, Michael J.; Reuschlé, Thierry; Erdmann, Saskia; Komorowski, Jean-Christophe; Cholik, Noer

    2016-04-01

    Low permeability dome rocks may contribute to conduit overpressure development in volcanic systems, indirectly abetting explosive activity. The permeability of dome-forming rocks is primarily controlled by the volume, type (vesicles and/or microcracks), and connectivity of the void space present. Here we investigate the permeability-porosity relationship of dome-forming rocks and pumice clasts from Merapi's 1888 to 2013 eruptions and assess their possible role in eruptive processes, with particular emphasis on the 2010 paroxysmal eruption. Rocks are divided into three simple field classifications common to all eruptions: Type 1 samples have low bulk density and are pumiceous in texture; Type 2 samples, ubiquitous to the 2010 eruption, are dark grey to black in hand sample and vary greatly in vesicularity; and Type 3 samples are weakly vesicular, light grey in hand sample, and are the only samples that contain cristobalite. Type 2 and Type 3 rocks are present in all eruptions and their permeability and porosity data define similar power law relationships, whereas data for Type 1 samples are clearly discontinuous from these trends. A compilation of permeability and porosity data for andesites and basaltic andesites with published values highlights two microstructural transitions that exert control on permeability, confirmed by modified Bayesian Information Criterion (BIC) analysis. Permeability is microcrack- and diktytaxitic-controlled at connected porosities, φc, < 10.5 vol.%; vesicle- and microcrack-controlled at 10.5 < φc < 31 vol.%; and likely vesicle-controlled for φc > 31 vol.%. Type 3 basaltic andesites, the least permeable of the measured samples and therefore the most likely to have originated in the uppermost low-permeability dome, are identified as relicts of terminal domes (the last dome extruded prior to quiescence). Cristobalite commonly found in the voids of Type 3 blocks may not contribute significantly to the reduction of the permeability of

  8. Debris avalanches and slumps on the margins of volcanic domes on Venus: Characteristics of deposits

    NASA Technical Reports Server (NTRS)

    Bulmer, M. H.; Guest, J. E.; Beretan, K.; Michaels, Gregory A.; Saunders, R. Stephen

    1992-01-01

    Modified volcanic domes, referred to as collapsed margin domes, have diameters greater than those of terrestrial domes and were therefore thought to have no suitable terrestrial analogue. Comparison of the collapsed debris using the Magellan SAR images with volcanic debris avalanches on Earth has revealed morphological similarities. Some volcanic features identified on the seafloor from sonar images have diameters similar to those on Venus and also display scalloped margins, indicating modification by collapse. Examination of the SAR images of collapsed dome features reveals a number of distinct morphologies to the collapsed masses. Ten examples of collapsed margin domes displaying a range of differing morphologies and collapsed masses have been selected and examined.

  9. Investigation of the Glacial History of the Siple Coast Using Radar-Detected Internal Layers and the Ice Core from Siple Dome

    NASA Astrophysics Data System (ADS)

    Winebrenner, D. P.; Conway, H.; Sylvester, J.

    2002-12-01

    The spatial patterns of post-glacial thinning on the West Antarctic Ice Sheet have evidently been complex; for example, Roosevelt Island has thinned more than 300m in the past 4000 years (Conway et al., Science 286, 1999), while 300 km to the south at Siple Dome, there has been little or no thinning (Nereson and Raymond, J. Glac. 47, 2001; J. White, pers. comm., 2002). Understanding past patterns of thinning and recession of the ice sheet is a crucial step toward understanding future possible changes. Radio-echo sounding of ice reveals internal reflecting layers, most of which are thought to result from the deposition of volcanic fallout on past ice sheet surfaces, and which hence represent isochrones. The age-depth relationship form the Siple Dome ice core (Taylor et al., JGR in review, 2002) allows dating of radar layers that are continuous for more than 100 km across the Dome. However, extending the timescale across the rest of the Siple Coast is problematic because the ice streams surrounding Siple Dome have disrupted the continuity of internal layers. Here we present preliminary results on the development of methods to extrapolate spatially the age-depth relationship from Siple Dome, using core data and data from the University of Washington monopulse radar, and beginning in particular with Ridge BC. In brief, these methods are: 1) Deconvolution of (an estimate of) the radar transmit waveform from radar echograms, so as to distill out the electromagnetic response of ice that depends only on essential, rather than changeable, characteristics of the radar. 2) Correspondence of radar layers with ice core measurements on Siple Dome, which shows fairly isolated radar layers linked to electrical conductivity (ECM) and volcanic sulfate features at 150, 190, 340, and 480 meters depth. An unusually large and thick ECM event at 215m depth marks the onset of a very distinctive radar layer that can be traced entirely across Siple Dome. 3) Identification, on the basis of

  10. Geological evaluation of Gulf Coast salt domes: overall assessment of the Gulf Interior Region

    SciTech Connect

    1981-10-01

    The three major phases in site characterization and selection are regional studies, area studies, and location studies. This report characterizes regional geologic aspects of the Gulf Coast salt dome basins. It includes general information from published sources on the regional geology; the tectonic, domal, and hydrologic stability; and a brief description the salt domes to be investigated. After a screening exercise, eight domes were chosen for further characterization: Keechi, Oakwood, and Palestine Domes in Texas; Vacherie and Rayburn's domes in North Louisiana; and Cypress Creek and Richton domes in Mississippi. A general description of each, maps of the location, property ownership, and surface geology, and a geologic cross section were presented for each dome.

  11. Geochemical controls of elevated arsenic concentrations in groundwater, Ester Dome, Fairbanks district, Alaska

    USGS Publications Warehouse

    Verplanck, P.L.; Mueller, S.H.; Goldfarb, R.J.; Nordstrom, D.K.; Youcha, E.K.

    2008-01-01

    Ester Dome, an upland area near Fairbanks, Alaska, was chosen for a detailed hydrogeochemical study because of the previously reported elevated arsenic in groundwater, and the presence of a large set of wells amenable to detailed sampling. Ester Dome lies within the Fairbanks mining district, where gold-bearing quartz veins, typically containing 2-3??vol.% sulfide minerals (arsenopyrite, stibnite, and pyrite), have been mined both underground and in open cuts. Gold-bearing veins on Ester Dome occur in shear zones and the sulfide minerals in these veins have been crushed to fine-grained material by syn- or post-mineralization movement. Groundwater at Ester Dome is circumneutral, Ca-HCO3 to Ca-SO4 type, and ranges from dilute (specific conductance of 48????S/cm) to more concentrated (specific conductance as high as 2070????S/cm). In general, solute concentrations increase down hydrologic gradient. Redox species indicate that the groundwaters range from oxic to sub-oxic (low dissolved oxygen, Fe(III) reduction, no SO4 reduction). Waters with the highest Fe concentrations, as high as 10.7??mg/L, are the most anoxic. Dissolved As concentrations range from < 1 to 1160????g/L, with a median value of 146????g/L. Arsenic concentrations are not correlated with specific conductance or Fe concentrations, suggesting that neither groundwater residence time, nor reductive dissolution of iron oxyhydroxides, control the arsenic chemistry. Furthermore, As concentrations do not covary with other constituents that form anions and oxyanions in solution (e.g., HCO3, Mo, F, or U) such that desorption of arsenic from clays or oxides also does not control arsenic mobility. Oxidation of arsenopyrite and dissolution of scorodite, in the near-surface environment appears to be the primary control of dissolved As in this upland area. More specifically, the elevated As concentrations are spatially associated with sulfidized shear zones and localities of gold-bearing quartz veins. Consistent with

  12. Advanced treatment of wet-spun acrylic fiber manufacturing wastewater using three-dimensional electrochemical oxidation.

    PubMed

    Zheng, Tianlong; Wang, Qunhui; Shi, Zhining; Fang, Yue; Shi, Shanshan; Wang, Juan; Wu, Chuanfu

    2016-12-01

    A three-dimensional electrochemical oxidation (3D-EC) reactor with introduction of activated carbon (AC) as particle micro-electrodes was applied for the advanced treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under the optimized conditions (current density of 500A/m(2), circulation rate of 5mL/min, AC dosage of 50g, and chloride concentration of 1.0g/L), the average removal efficiencies of chemical oxygen demand (CODcr), NH3-N, total organic carbon (TOC), and ultraviolet absorption at 254nm (UV254) of the 3D-EC reactor were 64.5%, 60.8%, 46.4%, and 64.8%, respectively; while the corresponding effluent concentrations of CODcr, NH3-N, TOC, and UV254 were 76.6, 20.1, and 42.5mg/L, and 0.08Abs/cm, respectively. The effluent concentration of CODcr was less than 100mg/L, which showed that the treated wastewater satisfied the demand of the integrated wastewater discharge standard (GB 8978-1996). The 3D-EC process remarkably improved the treatment efficiencies with synergistic effects for CODcr, NH3-N, TOC, and UV254 during the stable stage of 44.5%, 38.8%, 27.2%, and 10.9%, respectively, as compared with the sum of the efficiencies of a two-dimensional electrochemical oxidation (2D-EC) reactor and an AC adsorption process, which was ascribed to the numerous micro-electrodes of AC in the 3D-EC reactor. Gas chromatography mass spectrometry (GC-MS) analysis revealed that electrochemical treatment did not generate more toxic organics, and it was proved that the increase in acute biotoxicity was caused primarily by the production of free chlorine.

  13. Miocene calc-alkaline magmatism, calderas, and crustal extension in the Kofa and Castle Dome Mountains, southwestern Arizona

    NASA Astrophysics Data System (ADS)

    Grubensky, Michael J.; Bagby, William C.

    1990-11-01

    Two widespread lower Miocene rhyolite ash flow tuffs in the Kofa and Castle Dome mountains of southwestern Arizona are products of caldera-forming eruptions. These closely erupted tuffs, the tuff of Yaqui Tanks and the tuff of Ten Ewe Mountain, are approximately 22 Ma in age and their eruptions culminate a 1- to 2-m.y.-long burst of calc-alkaline volcanic activity centered on the northern Castle Dome Mountains. Exotic blocks of Proterozoic and Mesozoic crystalline rocks up to 20 m across are present in exposures of the tuff of Yaqui Tanks exposed in the central Castle Dome Mountains and the southern Kofa Mountains. A single, thick cooling unit of the tuff of Ten Ewe Mountain that includes thick lenses of mesobreccia marks the location of the younger caldera that extends from Palm Canyon in the western Kofa Mountains eastward more than 7 km along strike to the central part of the range. The tuffs show rapid thinning away from their inferred sources. They were probably associated with high-volume (100 kms) eruptions. Large residual Bouguer gravity anomalies, one beneath each inferred caldera, are interpreted as batholithic rocks or low-density caldera fill. Caldera-related volcanism in the Kofa region occurred during a transition in extensional tectonic regimes: from a regime of east-west trending uplifts and basins to a regime manifest primarily by northwest striking normal faults. A narrow corridor of folding and strike-slip faulting formed during volcanism in the southern Kofa Mountains. Upper Oligocene or lower Miocene coarse sedimentary rocks along the southern flank of the Chocolate Mountains anticlinorium in the southern Castie Dome Mountains mark the periphery of a basin similar to other early and middle Tertiary basins exposed in southern California. The volcanic section of the Kofa region was dissected by high-angle normal faults related to northeast-southwest oriented crustal extension typical of the southern Basin and Range province.

  14. Advanced imaging techniques III: a scalable and modular dome illumination system for scientific microphotography on a budget

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A scalable and modular LED illumination dome for microscopic scientific photography is described and illustrated, and methods for constructing such a dome are detailed. Dome illumination for insect specimens has become standard practice across the field of insect systematics, but many dome designs ...

  15. Boscovich as an engineer: the statics of masonry domes

    NASA Astrophysics Data System (ADS)

    Corradi Dell'Acqu, L.

    The collection of writings by Ruggiero Boscovich contains a certain number of studies that can be considered of ``engineering'' character, mostly focusing on problems of hydraulics and structural mechanics. Nevertheless, such studies hardly can be regarded as part of Boscovich's direct interest. They were usually meant at answering specific questions, when Boscovich was acting as a consultant for people that were facing serious problems of different kind and asked his advise, considered as precious because of the prestige that Boscovich enjoyed in his time. In this paper attention is focused on one problem, the statics of masonry domes, which Boscovich faced twice in two different contexts. In these studies he employed, to my knowledge for the first time for computation purposes, a failure mechanism that at the end of the century became the basis for systematic and rigorous methods for the analysis of arches, vaults and domes. Boscovich work can be regarded as anticipating these results.

  16. Does Flattened Sky Dome Reduces Perceived Moon Size

    NASA Astrophysics Data System (ADS)

    Toskovic, O.

    2009-09-01

    The aim of this study was to examine the Flattened sky dome model as an explanation of the Moon illusion. Two experiments were done, in a dark room, in which distribution of depth cues is the same towards horizon as towards zenith. In the first experiment 14 participants had the task to equalize the perceived distances of three stimuli in three directions (horizontal, tilted 45 degrees and vertical). In the second experiment 16 participants had the task to estimate the perceived sizes of three stimuli in the same three directions. For distance estimates we found differences among three directions in a way, that as the head tilts upwards, the perceived space is being elongated, which is the opposite to flattened sky dome. For size estimates we found no difference among the three directions.

  17. Elemental concentrations and inorganic isotopic ratios in surface snow along the route to Dome Fuji, Antarctica

    NASA Astrophysics Data System (ADS)

    Hirabayashi, M.; Nakazawa, F.; Azuma, K. G.; Motoyama, H.

    2015-12-01

    Snow ice sample in Antarctica contains particulate matter. Particulates originate from continent, volcano, sea, space, and organism. The particulate matter of continental origin contains many elements from minerals and rocks. The isotopic ratio of an element reflects the origin and the history of the particle. Since the isotopic ratio of inorganic species depends on the source, the information about the source contribution of particulate matter can be estimated by analyzing the isotopic ratios of inorganic species. In this research, concentrations of inorganic species and isotopic ratios of inorganic species (Ca, Sr, Nd) in snow collected on the route form coastal area to Dome Fuji station in Antarctica were analyzed. The snow samples were collected along ca. 1000 km traverse route from Mikaeridai (S16; 69°01'S, 40°03'E, 590 m) to Dome Fuji station (77°19'S, 39°42'E, 3810 m) by the Japan Antarctica research expedition. Those samples were collected in the 2007/2008 and 2009/2010 austral summer. The samples were transported to Japan without thawing. The quantitative analyses of inorganic species were measured using ICP quadrupole type mass spectrometer. The isotopic ratios of isolated inorganic species were measured using ICP magnetic field type mass spectrometer. Further results and discussion about the behavior and origin of sulfur species in snow will be presented.

  18. Stability of a dome-shape liquid film for conditions when it flows around a plate

    NASA Astrophysics Data System (ADS)

    Dekhtyar, R. A.; Slesareva, E. Yu; Ovchinnikov, V. V.

    2016-10-01

    The experimental research of hydrodynamic stability of a dome-shape film of liquid for the conditions, when it flows around a thin plate has been carried out. Experiments have been executed for a case of Savart "water bell". An axisymmetrical film has been formed by the impact of a liquid jet with the width of 10 mm on a solid disc with the diameter of 14.5 mm. The width of the thin plate, streamlined by a dome-shape water film, was varied from 0.05 to 3.5 mm. The wide side of the plate was located at two angles relative to the direction of the flow velocity vector in a film: along and across, at various distances from the disc. Stability of the "water bell" surface has been considered and general stability criterion showing its sensitivity to the angle of plate orientation has been derived. The critical Weber number, above which the discontinuity of bell surface appears, and threshold value of the Weber number, below which it coalescences, have been defined. It was shown, that the critical and threshold Weber numbers depend on the Reynolds number.

  19. Emplacement of an Archean gneiss dome, northern Ontario, Canada: Inflation inferred from magnetic fabrics

    NASA Astrophysics Data System (ADS)

    Borradaile, G. J.; Gauthier, D.

    2003-04-01

    Previous field structural studies of the Ash Bay gneiss dome revealed an upward convex foliation with an integral east-west lineation defined by a quartzo-felspathic matrix. Unfortunately, the amphibolite facies gneisses lack traditional indicators of microfabric evolution, such as kinematic indicators, so that it is difficult to relate the foliation's orientation distribution to an emplacement mechanism for the dome. Fortunately, anisotropy of magnetic susceptibility isolates a distinct microfabric because of the preferred orientation of high-susceptibility, accessory magnetite. The magnetite subfabric developed late in the metamorphic crystallization history, and its magnetic foliation and magnetic lineation are similarly oriented to the S-L fabric of the quartz-feldspar matrix. However, the magnetite foliation dips less steeply and forms a less convex domal surface than the field schistosity. The metamorphic schistosity and the magnetite foliation thus isolate the domal deflection at different stages, confirming the inflation and upward motion of the Ash Bay diapir during the closing stages of amphibolite facies metamorphism.

  20. Kaguyak dome field and its Holocene caldera, Alaska Peninsula

    USGS Publications Warehouse

    Fierstein, J.; Hildreth, W.

    2008-01-01

    Kaguyak Caldera lies in a remote corner of Katmai National Park, 375??km SW of Anchorage, Alaska. The 2.5-by-3-km caldera collapsed ~ 5.8 ?? 0.2??ka (14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80??km southwest. Postcaldera events include filling the 150-m-deep caldera lake, emplacement of two intracaldera domes (61.5-64.5% SiO2), and phreatic ejection of lakefloor sediments onto the caldera rim. CO2 and H2S bubble up through the lake, weakly but widely. Geochemical analyses (n = 148), including pre-and post-caldera lavas (53-74% SiO2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60??ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200??years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep caldera wall, which beheads gullies incised into the breccia deposit prior to caldera formation. They were probably shed by a large lava dome extruding where the lake is today.

  1. Kaguyak dome field and its Holocene caldera, Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Fierstein, Judy; Hildreth, Wes

    2008-10-01

    Kaguyak Caldera lies in a remote corner of Katmai National Park, 375 km SW of Anchorage, Alaska. The 2.5-by-3-km caldera collapsed ~ 5.8 ± 0.2 ka ( 14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO 2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80 km southwest. Postcaldera events include filling the 150-m-deep caldera lake, emplacement of two intracaldera domes (61.5-64.5% SiO 2), and phreatic ejection of lakefloor sediments onto the caldera rim. CO 2 and H 2S bubble up through the lake, weakly but widely. Geochemical analyses ( n = 148), including pre-and post-caldera lavas (53-74% SiO 2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60 ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200 years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO 2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep caldera wall, which beheads gullies incised into the breccia deposit prior to caldera formation. They were probably shed by a large lava dome extruding where the lake is today.

  2. Augmentation mastopexy using adjustable implants with external injection domes.

    PubMed

    Becker, Hilton; Hartog, Jeffrey

    2006-01-01

    For augmentation mastopexy, the authors use adjustable implants that are deflated at the end of the procedure and then inflated to the desired size 5 to 10 days postoperatively using external injection domes. Reported advantages, based on 175 cases, include increased perioperative safety for the nipple areolar complex, the ability to adjust for size and symmetry postoperatively with patient input, and better scar healing with less widening.

  3. Mini-dome Fresnel lens photovoltaic concentrator development

    NASA Technical Reports Server (NTRS)

    Oneill, Mark J.; Piszczor, Michael F., Jr.

    1991-01-01

    Since 1986 work on a new high-performance, light-weight space photovoltaic concentration array has been conducted. An update on the mini-dome lens concentrator array development program is provided. Recent prototype cell and lens test results indicate that near-term array performance goals of 300 w/sq m and 100 w/kg are feasible, and that a longer-term goal of 200 w/kg is reasonable.

  4. Dual innervation of neonatal Merkel cells in mouse touch domes.

    PubMed

    Niu, Jingwen; Vysochan, Anna; Luo, Wenqin

    2014-01-01

    Merkel cell-neurite complexes are specialized mechanosensory end organs that mediate discriminative touch sensation. It is well established that type I slowly adapting (SAI) mechanoreceptors, which express neural filament heavy chain (NFH), innervate Merkel cells. It was previously shown that neurotrophic factor NT3 and its receptor TrkC play crucial roles in controlling touch dome Merkel cell innervation of NFH+ fibers. In addition, nerve fibers expressing another neurotrophic tyrosine receptor kinase (NTRK), Ret, innervate touch dome Merkel cells as well. However, the relationship between afferents responsive to NT3/TrkC signaling and those expressing Ret is unclear. It is also controversial if these Ret+ fibers belong to the early or late Ret+ DRG neurons, which are defined based on the co-expression and developmental dependence of TrkA. To address these questions, we genetically traced Ret+ and TrkC+ fibers and analyzed their developmental dependence on TrkA. We found that Merkel cells in neonatal mouse touch domes receive innervation of two types of fibers: one group is Ret+, while the other subset expresses TrkC and NFH. In addition, Ret+ fibers depend on TrkA for their survival and normal innervation whereas NFH+ Merkel cell innervating fibers are almost unaltered in TrkA mutant mice, supporting that Ret+ and NFH+/TrkC+ afferents are two distinct groups. Ret signaling, on the other hand, plays a minor role for the innervation of neonatal touch domes. In contrast, Merkel cells in the glabrous skin are mainly contacted by NFH+/TrkC+ afferents. Taken together, our results suggest that neonatal Merkel cells around hair follicles receive dual innervation while Merkel cells in the glabrous skin are mainly innervated by only SAI mechanoreceptors. In addition, our results suggest that neonatal Ret+ Merkel cell innervating fibers most likely belong to the late but not early Ret+ DRG neurons.

  5. Analysis of the TMI-2 dome radiation monitor

    SciTech Connect

    Murphy, M B; Mueller, G M; Jernigan, W C

    1985-08-01

    Questions have been raised regarding the accuracy of the in-containment radiation readings from the LOCA qualified, dome radiation monitor, HP-R-214 during the March 28, 1979 accident at the Three Mile Island Unit 2 Reactor. This report discusses the accuracy of the readings, gives the results of examining the radiation monitor itself, and estimates the radiation environment inside containment during the accident.

  6. ON THE NATURE OF RECONNECTION AT A SOLAR CORONAL NULL POINT ABOVE A SEPARATRIX DOME

    SciTech Connect

    Pontin, D. I.; Priest, E. R.; Galsgaard, K.

    2013-09-10

    Three-dimensional magnetic null points are ubiquitous in the solar corona and in any generic mixed-polarity magnetic field. We consider magnetic reconnection at an isolated coronal null point whose fan field lines form a dome structure. Using analytical and computational models, we demonstrate several features of spine-fan reconnection at such a null, including the fact that substantial magnetic flux transfer from one region of field line connectivity to another can occur. The flux transfer occurs across the current sheet that forms around the null point during spine-fan reconnection, and there is no separator present. Also, flipping of magnetic field lines takes place in a manner similar to that observed in the quasi-separatrix layer or slip-running reconnection.

  7. Small domes on Venus: probable analogs of Icelandic lava shields

    USGS Publications Warehouse

    Garvin, James B.; Williams, Richard S.

    1990-01-01

    On the basis of observed shapes and volumetric estimates, we interpret small, dome-like features on radar images of Venus to be analogs of Icelandic lava-shield volcanoes. Using morphometric data for venusian domes in Aubele and Slyuta (in press), as well as our own measurements of representative dome volumes and areas from Tethus Regio, we demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS ). LILS are slightly convex in cross-section with typical flank slopes of ∼3°. Plausible lava-shield-production rates for the venusian plains suggest formation of ∼53 million shields over the past 0.25 Ga. The cumulative global volume of lava that would be associated with this predicted number of lava shields is only a factor of 3–4 times that of a single oceanic composite shield volcano such as Mauna Loa. The global volume of all venusian lava shields in the 0.5–20-km size range would only contribute a meter of resurfacing over geologically significant time scales. Thus, venusian analogs to LILS may represent the most abundant landform on the globally dominant plains of Venus, but would be insignificant with regard to the global volume of lava extruded. As in Iceland, associated lavas from fissure eruptions probably dominate plains volcanism and should be evident on the higher resolution Magellan radar images.

  8. Cybersickness Following Repeated Exposure to DOME and HMD Virtual Environments

    NASA Technical Reports Server (NTRS)

    Taylor, Laura C.; Harm, Deborah L.; Kennedy, Robert S.; Reschke, Millard F.; Loftin, R. Bowen

    2011-01-01

    Virtual environments (VE) offer unique training opportunities, including training astronauts to preadapt them to the novel sensory conditions of microgravity. However, one unresolved issue with VE use is the occurrence of cybersickness during and following exposure to VE systems. Most individuals adapt and become less ill with repeated interaction with VEs. The goal of this investigation was to compare motion sickness symptoms (MSS) produced by dome and head-mounted (HMD) displays and to examine the effects of repeated exposures on MSS. Sixty-one subjects participated in the study. Three experimental sessions were performed each separated by one day. The subjects performed a navigation and pick and place task in either a dome or HMD VE. MSS were measured using a Simulator Sickness Questionnaire before, immediately after, and at 1, 2, 4 and 6 hours following exposure to the VEs. MSS data were normalized by calculating the natural log of each score and an analysis of variance was performed. We observed significant main effects for day and time and a significant day by time interaction for total sickness and for each of the subscales, nausea, oculomotor and disorientation. However, there was no significant main effect for device. In conclusion, subjects reported a large increase in MSS immediately following exposure to both the HMD and dome, followed by a rapid recovery across time. Sickness severity also decreased over days, which suggests that subjects become dual-adapted over time making VE training a viable pre-flight countermeasure for space motion sickness.

  9. An Operationally Based Vision Assessment Simulator for Domes

    NASA Technical Reports Server (NTRS)

    Archdeacon, John; Gaska, James; Timoner, Samson

    2012-01-01

    The Operational Based Vision Assessment (OBVA) simulator was designed and built by NASA and the United States Air Force (USAF) to provide the Air Force School of Aerospace Medicine (USAFSAM) with a scientific testing laboratory to study human vision and testing standards in an operationally relevant environment. This paper describes the general design objectives and implementation characteristics of the simulator visual system being created to meet these requirements. A key design objective for the OBVA research simulator is to develop a real-time computer image generator (IG) and display subsystem that can display and update at 120 frame s per second (design target), or at a minimum, 60 frames per second, with minimal transport delay using commercial off-the-shelf (COTS) technology. There are three key parts of the OBVA simulator that are described in this paper: i) the real-time computer image generator, ii) the various COTS technology used to construct the simulator, and iii) the spherical dome display and real-time distortion correction subsystem. We describe the various issues, possible COTS solutions, and remaining problem areas identified by NASA and the USAF while designing and building the simulator for future vision research. We also describe the critically important relationship of the physical display components including distortion correction for the dome consistent with an objective of minimizing latency in the system. The performance of the automatic calibration system used in the dome is also described. Various recommendations for possible future implementations shall also be discussed.

  10. Microstructure and electrochemical hydrogenation/dehydrogenation performance of melt-spun La-doped Mg{sub 2}Ni alloys

    SciTech Connect

    Hou, Xiaojiang; Hu, Rui; Zhang, Tiebang Kou, Hongchao; Song, Wenjie; Li, Jinshan

    2015-08-15

    This work focuses on microstructure and electrochemical hydrogen storage properties of La-doped Mg{sub 2}Ni alloys. The alloys with nominal compositions of Mg{sub 2}Ni{sub 1−x}La{sub x} (x = 0, 0.1, 0.3, 0.5) were prepared via metallurgical smelting and melt-spun on a rotating copper wheel. The scanning electron microscope, X-ray diffraction, differential scanning calorimetry and transition electron microscope, galvanostatic charging/discharging and other electrochemical measurements were employed to investigate. The results show that the increasing of La content and melt-spinning speed favors the formation of Mg–Ni–La amorphous/nanocrystalline alloys. It is found that the melt-spun ribbons display increased discharge capacities and superior cycle stabilities compared to the as-cast alloys with and without La. The potentiodynamic polarization results indicate that melt-spun La-doped Mg{sub 2}Ni ribbons possess more positive corrosion potential E{sub corr} and exhibit relatively high corrosion resistance against the alkaline solution. The mechanism for electrochemical hydrogenation/dehydrogenation has been proposed based on the effect of microstructures on the mass/charge transfer process for electrode electrochemical reaction. - Highlights: • Nanocrystalline/amorphous Mg–Ni–La alloys are obtained by melt-spinning. • Microstructures of as-cast and rapid quenched Mg{sub 2}Ni{sub 1−x}La{sub x} alloys are investigated. • Electrochemical hydrogenation properties of experimental alloys are characterized. • Electrochemical hydrogen absorption/desorption mechanism is proposed.

  11. Lunar Mare Dome Identification and Morphologic Properties Analysis Using Chang'E-2 Lunar Data

    NASA Astrophysics Data System (ADS)

    Zeng, Xingguo; Mu, Lingli; Li, Chunlai; Liu, Jianjun; Ren, Xin; Wang, Yuanyuan

    2016-04-01

    Identify the lunar mare dome and study the morphologic properties to know more knowledge about the structure will enhance the study of lunar volcanism. Traditionally, most lunar domes are identified by the scientists from exploring the images or topographic maps of the lunar surface with manual method, which already found out a bunch of lunar domes in specific local areas. For the purpose of getting more knowledge about global lunar dome, it is necessary to identify the lunar dome from the global lunar mare. However, it is hard to find new lunar domes from the global lunar mare only with manual method, since in that case, the large volume lunar data is needed and such work is too time consumed, so that, there are few researchers who have indentified and study the properties of the lunar dome from the perspective of lunar global scale. To solve the problem mentioned above, in this approach , CE-2 DEM, DOM data in 7m resolution were used in the detection and morphologic analysis of the lunar domes and a dome detection method based on topographic characteristics were developed.We firstly designed a method considering the morphologic characteristics to identify the lunar dome with Chang'E2(CE-2) lunar global data, after that, the initial identified result with properties is analyzed, and finally, by integrating the result with lunar domes already found by former researchers, we made some maps about the spatial distribution of the global lunar mare dome. With the CE-2 data covering the former lunar domes and the new found lunar domes, we surveyed and calculated some morphologic properties, and found that, lunar domes are circular or eclipse shaped, obviously different from background in topography,which has a average diameter between 3-25km, circular degree less than 1.54, with a average slope less than 10°, average height less than 650m and diameter/height less than 0.065. Almost all of the lunar domes are located in the extent of 58°N~54°S,167°W~180°E,and nearly

  12. Ferrule and use thereof for cooling a melt spun hollow glass fiber as it emerges from a spinnerette

    DOEpatents

    Brown, William E.

    1977-01-01

    An improvement in the process of melt spinning thin walled, hollow fibers from relatively low melting glasses results if cooling of the emerging fiber is accomplished by use of a thin layer of gas to transfer heat from the fiber to a ferrule which fits closely to the spinnerette face and the individual fiber. The ferrule incorporates or is in contact with a heat sink and is slotted or segmented so that it may be brought into position around the moving fiber. Thinner walled, more uniform fibers may be spun when this method of cooling is employed.

  13. Granitoid magmatism of Alarmaut granite-metamorphic dome, West Chukotka, NE Russia

    NASA Astrophysics Data System (ADS)

    Luchitskaya, M. V.; Sokolov, S. D.; Bondarenko, G. E.; Katkov, S. M.

    2009-04-01

    Main tectonic elements of West Chukotka are Alazey-Oloy, South-Anyui and Anyui-Chukotka fold systems, formed as a result of collision between structures of North-Asian continent active margin and Chukotka microcontinent [1-3]. South-Anyui fold system, separating Alazey-Oloy and Anyui-Chukotka systems, is considered as suture zon, formed as a result of oceanic basin closing [4-6]. Continent-microcontinent collision resulted in formation of large orogen with of northern and southern vergent structures, complicated by strike-slip deformations [7, 8]. Within Anyui-Chukotka fold system several rises, where most ancient deposits (crystalline basement and Paleozoic cover of Chukotka microcontinent) are exposed, were distinguished [2, 9-11]. Later they were considered as granite-metamorphic domes [12-14]. Alarmaut dome is located at West Chukotka to the north from Bilibino city and is traced from south to north in more than 120 km. General direction of structure is discordant to prevailing NW extensions of tectonic elements of the region. Paleozoic-Triassic deposits are exposed within the Alarmaut dome: 1) D3-C1 - crystalline schists, quartz-feldspar metasandstones, quartzites, marbles (700 m) [11]; 2) C1 - marblized limestones, quartz-feldspar metasandstones, quartzites, amphibole-pyroxene crystalline schists. Limestones contain corals, indicating Visean age of deposits [11]. Metamorphism reaches amphibolite facies, maximum P-T conditions are 660°С and 5 kbar. Migmatites, indicating in situ partial melting, are observed. Intensity of deformations of Paleozoic rocks increases at the boundary with Triassic deposits [11]; in the western part of dome slices of Pz rocks are separated by blastomylonite horizons [14]. Within Alramaut dome granitoids of Lupveem batholith (central part of dome), Bystrinsky pluton (southeastern part), and small Koyvel' and Kelil'vun plutons were studied. New U-Pb SHRIMP zircon data indicate Early Cretaceous (117-112 m.a.) age of granitoids [15

  14. Design and Development of a Composite Dome for Experimental Characterization of Material Permeability

    NASA Technical Reports Server (NTRS)

    Estrada, Hector; Smeltzer, Stanley S., III

    1999-01-01

    This paper presents the design and development of a carbon fiber reinforced plastic dome, including a description of the dome fabrication, method for sealing penetrations in the dome, and a summary of the planned test series. This dome will be used for the experimental permeability characterization and leakage validation of composite vessels pressurized using liquid hydrogen and liquid nitrogen at the Cryostat Test Facility at the NASA Marshall Space Flight Center (MSFC). The preliminary design of the dome was completed using membrane shell analysis. Due to the configuration of the test setup, the dome will experience some flexural stresses and stress concentrations in addition to membrane stresses. Also, a potential buckling condition exists for the dome due to external pressure during the leak testing of the cryostat facility lines. Thus, a finite element analysis was conducted to assess the overall strength and stability of the dome for each required test condition. Based on these results, additional plies of composite reinforcement material were applied to local regions on the dome to alleviate stress concentrations and limit deflections. The dome design includes a circular opening in the center for the installation of a polar boss, which introduces a geometric discontinuity that causes high stresses in the region near the hole. To attenuate these high stresses, a reinforcement system was designed using analytical and finite element analyses. The development of a low leakage polar boss system is also investigated.

  15. Glacier melting during lava dome growth at Nevado de Toluca volcano (Mexico): Evidences of a major threat before main eruptive phases at ice-caped volcanoes

    NASA Astrophysics Data System (ADS)

    Capra, L.; Roverato, M.; Groppelli, G.; Caballero, L.; Sulpizio, R.; Norini, G.

    2015-03-01

    Nevado de Toluca volcano is one of the largest stratovolcanoes in the Trans-Mexican Volcanic Belt. During Late Pleistocene its activity was characterized by large dome growth and subsequent collapse emplacing large block and ash flow deposits, intercalated by Plinian eruptions. Morphological and paleoclimate studies at Nevado de Toluca and the surrounding area evidenced that the volcano was affected by extensive glaciation during Late Pleistocene and Holocene. During the older recognized glacial period (27-60 ka, MIS 3), the glacier was disturbed by the intense magmatic and hydrothermal activity related to two dome extrusion episodes (at 37 ka and 28 ka). Glacier reconstruction indicates maximum ice thickness of 90 m along main valleys, as at the Cano ravines, the major glacial valley on the northern slope of the volcano. Along this ravine, both 37 and 28 ka block-and-ash deposits are exposed, and they directly overlay a fluviatile sequence, up to 40 m-thick, which 14C ages clearly indicate that their emplacement occurred just before the dome collapsed. These evidences point to a clear interaction between the growing dome and its hydrothermal system with the glacier. During dome growth, a large amount of melting water was released along major glacial valleys forming thick fluvioglacial sequences that were subsequently covered by the block-and-ash flow deposits generated by the collapse of the growing dome. Even though this scenario is no longer possible at the Nevado de Toluca volcano, the data presented here indicate that special attention should be paid to the possible inundation areas from fluviatile/lahar activity prior to the main magmatic eruption at ice-capped volcanoes.

  16. Features of West Hackberry SPR Caverns and Internal Structure Of the Salt Dome

    SciTech Connect

    Munson, Darrell Eugene

    2006-09-01

    The intent of this report is to examine the internal structure of the West Hackberry salt dome utilizing the information from the geometric configuration of the internal cavern surfaces obtained from graphical representations of sonar survey data. In a general sense, the caverns of West Hackberry are remarkable in the symmetry of their shapes. There are only rather moderate deviations from what would be considered an ideal cylindrical solution mining geometry in these caverns. This finding is in marked contrast to the directional solutioning found in the elliptical cross sectioned, sometimes winged, caverns of Big Hill. None of the persistent lineaments prevalent in Big Hill caverns are evident in West Hackberry caverns. Irregularities of the West Hackberry caverns are restricted to preferential solution formed pits and protuberances with moderate dimensions. In fact, the principal characteristic of West Hackberry caverns is the often large sections of smooth and cylindrical cavern wall. Differences in the cavern characteristics between West Hackberry and Big Hill suggest that the former dome is quite homogeneous, while the latter still retains strong remnants of the interbeds of the original bedded Louann salt. One possible explanation is that the source of the two domes, while both from the Louann mother salt, differs. While the source of the Big Hill dome is directly from the mother salt bed, it appears that the West Hackberry arises from a laterally extruded sill of the mother salt. Consequently, the amount of deformation, and hence, mixing of the salt and interbed material in the extruded sill is significantly greater than would be the case for the directly formed diapir. In West Hackberry, remnants of interbeds apparently no longer exist. An important aspect of the construction of the West Hackberry caverns is the evidence of an attempt to use a uniform solutioning construction practice. This uniformity involved the utilization of single well solutioning and

  17. Constraints on the source of resurgent doming inferred from analogue and numerical modeling - Implications on the current feeding system of the Yenkahe dome-Yasur volcano complex (Vanuatu)

    NASA Astrophysics Data System (ADS)

    Brothelande, E.; Peltier, A.; Got, J.-L.; Merle, O.; Lardy, M.; Garaebiti, E.

    2016-08-01

    Resurgence, defined as the post-collapse long-term uplift of a caldera floor, is commonly attributed to a renewed rise of magma. The Yenkahe dome (Vanuatu) exhibits a common morphology - elongated with a graben on top - among resurgent domes, and is also one of the most active structures of the kind. In this study, we performed a joint analysis based on analogue and finite element numerical models to (1) constrain the width and depth of the long-term deformation intrusive source of the Yenkahe dome and (2) discuss the close association between the Yenkahe dome and the active Yasur cone. We consider the resurgent deformation at the surface to be driven by the uplift of a magma reservoir roof in depth. As the edifice deformation response depends on the medium and the source properties, the mechanical behavior of the upper crust and the nature of the source are modeled using two very different sets of hypotheses. Analogue modeling uses silicone putty, an analogue for a large viscous magma body, intruding a sand-plaster mixture reproducing a Mohr-Coulomb behavior for the crust. Numerical models consider the vertical displacement of a rigid indenter, allowing the conservation of a flat-shaped roof, into an elastoplastic material. Numerical and analogue models show different resurgent dome structures at depth but similar dome and graben morphologies in the surface. Inverse faults - or equivalent shearing zones - delimiting the dome provide an explanation for the confined nature of resurgent doming and the persistent volcanic activity on the dome border represented by the Yasur volcano. Analogue and numerical models together provide an estimation range of 1-1.8 km for the intrusive deformation source depth, and 1.3-2 km for its width. The proposed association between the Yenkahe dome and the Yasur volcano is compatible with such a shallow depth of the magma reservoir, and argues for a discontinuous resurgence process.

  18. Microbial characterization of microbial ecosystems associated to evaporites domes of gypsum in Salar de Llamara in Atacama desert.

    PubMed

    Rasuk, Maria Cecilia; Kurth, Daniel; Flores, Maria Regina; Contreras, Manuel; Novoa, Fernando; Poire, Daniel; Farias, Maria Eugenia

    2014-10-01

    The Central Andes in northern Chile contains a large number of closed basins whose central depression is occupied by saline lakes and salt crusts (salars). One of these basins is Salar de Llamara (850 m a.s.l.), where large domed structures of seemingly evaporitic origin forming domes can be found. In this work, we performed a detailed microbial characterization of these domes. Mineralogical studies revealed gypsum (CaSO(4)) as a major component. Microbial communities associated to these structures were analysed by 454 16S rDNA amplicon sequencing and compared between winter and summer seasons. Bacteroidetes Proteobacteria and Planctomycetes remained as the main phylogenetic groups, an increased diversity was found in winter. Comparison of the upper air-exposed part and the lower water-submerged part of the domes in both seasons showed little variation in the upper zone, showing a predominance of Chromatiales (Gammaproteobacteria), Rhodospirillales (Alphaproteobacteria), and Sphingobacteriales (Bacteroidetes). However, the submerged part showed marked differences between seasons, being dominated by Proteobacteria (Alpha and Gamma) and Verrucomicrobia in summer, but with more diverse phyla found in winter. Even though not abundant by sequence, Cyanobacteria were visually identified by scanning electron microscopy (SEM), which also revealed the presence of diatoms. Photosynthetic pigments were detected by high-performance liquid chromatography, being more diverse on the upper photosynthetic layer. Finally, the system was compared with other endoevaporite, mats microbialite and Stromatolites microbial ecosystems, showing higher similitude with evaporitic ecosystems from Atacama and Guerrero Negro. This environment is of special interest for extremophile studies because microbial life develops associated to minerals in the driest desert all over the world. Nevertheless, it is endangered by mining activity associated to copper and lithium extraction; thus, its

  19. Merapi's lava dome splitting explosion on 18 November 2013 observed by lidar and digital image correlation analysis.

    NASA Astrophysics Data System (ADS)

    Darmawan, Herlan; Walter, Thomas; Nikkhoo, Mehdi; Richter, Nicole

    2015-04-01

    After the 2010 Merapi eruption, the lava dome in the summit of the volcano was firstly growing and then subject to gradual cooling and contraction. In November 2013, a major phreatomagmatic explosion occurred, which caused an eruption column rising over 2 km high and destroyed a number of monitoring instruments in the near field. Bombs were thrown out over 1 km distance. The eruption produced volcanic ash and very fine materials. Deformation data from tilt or EDM showed no wide inflation or deflation associated with this eruption. In addition, high resolution TerraSAR-X data analysis also showed no edifice-wide deformation (Walter et al., 2015). Here we further examine two datasets to determine the morphologic and structural effects of this eruption. First we exploit fixed installed monitoring cameras and use a digital image correlation method to investigate geometric changes before and after the eruption. Second we acquired a high resolution terrestrial Lidar data set after the explosion and compared this another lidar data set acquired before. The result shows details on the splitted dome, the volume of the eruption and thickness of the deposits, and suggests that a new block at the front of the dome is inherently unstable and might break off to form a block and ash flow in the near future. Reference: TR Walter, Subandriyo J, Kirbani S, Bathke H, Suryanto W, Aisyah N, Darmawan H, Jousset P, Lühr BG, Dahm T (2015) Volcano-tectonic control of Merapi's lava dome splitting: The November 2013 fracture observed from high resolution TerraSAR-X data. Tectonophysics 639, 12 January 2015, Pages 23-33. doi:10.1016/j.tecto.2014.11.007

  20. Venus pancake dome formation: Morphologic effects of a cooling-induced variable viscosity during emplacement

    NASA Technical Reports Server (NTRS)

    Sakimoto, S. E. H.; Zuber, M. T.

    1993-01-01

    The distinctive steep-sided 'pancake' domes discovered in the Magellan images of Venus have morphologies that suggest formation by a single continuous emplacement of a high viscosity magma. A resemblance of the venusian domes to much smaller terrestrial rhyolite and dacite volcanic domes has prompted some authors to suggest that the domes on Venus also have high silica compositions and thus, high viscosities. However, viscosity is a function of crystallinity as well as silica content in a magma, and thus increases as a result of magmatic cooling. To investigate the effect of a cooling-induced viscosity increase on dome morphology, we have modeled the domes as radial viscous gravity currents that cool during emplacement. Various aspects of the investigation are discussed.

  1. Conceptual model for regional radionuclide transport from a salt dome repository: a technical memorandum

    SciTech Connect

    Kier, R.S.; Showalter, P.A.; Dettinger, M.D.

    1980-05-30

    Disposal of high-level radioactive wastes is a major environmental problem influencing further development of nuclear energy in this country. Salt domes in the Gulf Coast Basin are being investigated as repository sites. A major concern is geologic and hydrologic stability of candidate domes and potential transport of radionuclides by groundwater to the biosphere prior to their degradation to harmless levels of activity. This report conceptualizes a regional geohydrologic model for transport of radionuclides from a salt dome repository. The model considers transport pathways and the physical and chemical changes that would occur through time prior to the radionuclides reaching the biosphere. Necessary, but unknown inputs to the regional model involve entry and movement of fluids through the repository dome and across the dome-country rock interface and the effect on the dome and surrounding strata of heat generated by the radioactive wastes.

  2. Microchemistry and magnetization reversal mechanism in melt-spun 2:17-type Sm-Co magnets

    NASA Astrophysics Data System (ADS)

    Yan, A.; Gutfleisch, O.; Gemming, T.; Müller, K.-H.

    2003-09-01

    The stability of microstructure and of microchemistry in melt-spun precipitation-hardened Sm(Co,Fe,Cu,Zr)z magnets at high temperature and its effect on the magnetic properties, especially the coercivity at room temperature, were investigated by transmission electron microscopy, nanoprobe chemical analysis, and magnetic measurements. A very large gradient of the Cu content within the 1:5-type cell boundary phase was observed in highly coercive melt-spun Sm(Co,Fe,Cu,Zr)z magnets with uniform cellular structure. After an additional isothermal aging at 850 °C for 5 min, the coercivity is reduced dramatically from 3 T to 0.16 T. This is accompanied by the disappearance of the large gradient of Cu content within the cell boundary phase. Thus, it is proposed that the high coercivity in 2:17 Sm-Co magnets originates from the large gradient of domain wall energy within the Sm(Co,Cu)5 cell boundary phase. This gradient is caused by a very rapid phase separation taking place within the cell boundary phase during slow cooling.

  3. Comparative proteomics reveal diverse functions and dynamic changes of Bombyx mori silk proteins spun from different development stages.

    PubMed

    Dong, Zhaoming; Zhao, Ping; Wang, Chen; Zhang, Yan; Chen, Jianping; Wang, Xin; Lin, Ying; Xia, Qingyou

    2013-11-01

    Silkworms (Bombyx mori) produce massive amounts of silk proteins to make cocoons during the final stages of larval development. Although the major components, fibroin and sericin, have been the focus for a long time, few researchers have realized the complexity of the silk proteome. We collected seven kinds of silk fibers spun by silkworm larvae at different developmental stages: the silks spun by new hatched larvae, second instar day 0 larvae, third instar day 0 larvae, fourth instar day 0 larvae, and fourth instar molting larvae, the scaffold silk used to attach the cocoon to the substrate and the cocoon silk. Analysis by liquid chromatography-tandem mass spectrometry identified 500 proteins from the seven silks. In addition to the expected fibroins, sericins, and some known protease inhibitors, we also identified further protease inhibitors, enzymes, proteins of unknown function, and other proteins. Unsurprisingly, our quantitative results showed fibroins and sericins were the most abundant proteins in all seven silks. Except for fibroins and sericins, protease inhibitors, enzymes, and proteins of unknown function were more abundant than other proteins. We found significant change in silk protein compositions through development, being consistent with their different biological functions and complicated formation.

  4. Deformation, lava dome evolution, and eruption cyclicity at Merapi volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Young, Kirby D.

    Deformation monitoring results are reported here for the period 1988-1998 at Merapi volcano, one of the most active and dangerous volcanoes in Indonesia. Comprehensive databases of various geophysical parameters were concurrently studied and analyzed to 2000, and similar data were subsequently considered during periods of eruption crisis in 2001 and 2006. Of particular emphasis was the study of lava eruption rates based on dome volume estimates and seismic proxies for dome collapse volumes. The detailed study period of deformation includes a major resumption in lava effusion in January 1992 and major dome collapses in November 1994, January 1997, and July 1998. Monitoring techniques employed in the field are of two types. Translational movements were recorded via electronic distance measurements (EDM) on a summit trilateration network, slope distance changes measured to the upper flanks, and other data collected from 1988 to 1995. Tilt changes were detected by a summit and flank network of tilt stations that operated at various times from 1993 to 1998. A major consequence of the deformation results is the documentation of a significant 4-year period of deformation precursory to the 1992 eruption. Cross-crater strain rates accelerated from less than 3 x 10-6/day between 1988 and 1990 to more than 11 x 10-6/day just prior to the January 1992 activity, representing a general, asymmetric extension of the summit during highlevel conduit pressurization. After the vent opened and effusion of lava resumed, strain occurred at a much reduced rate of less than 2 x 10-6/day. The Gendol breach, a pronounced depression formed by the juxtaposition of old lava coulees on the southeast flank, functioned as a major displacement discontinuity. An elevated phase of magma production with respect to the long-term rate for the 20th Century characterized the activity at Merapi volcano, Central Java/Yogyakarta, Indonesia, for the period 1992-2006. Most large (0.2 - 3.4 x 106 m3) dome

  5. The Dome Automations of ATA50 and MASS-DIMM Telescopes for DAG Project

    NASA Astrophysics Data System (ADS)

    Dogan, E.; Celik, H. I.; Ozbaldan, E. E.; Guney, Y.; Yesilyaprak, C.

    2016-12-01

    In the scope of Eastern Anatolia Observatory (DAG) Project, The DAG Technical Team has carried out various automation studies like dome, camera, atmospherical equipments, etc. The domes of ATA50 and MASS-DIMM Telescopes have almost similar opening systems. Both telescopes will run as robotic very soon; therefore it's mandatory and inevitable to make the automations of their domes. The automation studies as its electronics and software developed by DAG Technical Team are presented.

  6. The geology and mechanics of formation of the Fort Rock Dome, Yavapai County, Arizona

    USGS Publications Warehouse

    Fuis, Gary S.

    1996-01-01

    The Fort Rock Dome, a craterlike structure in northern Arizona, is the erosional product of a circular domal uplift associated with a Precambrian shear zone exposed within the crater and with Tertiary volcanism. A section of Precambrian to Quaternary rocks is described, and two Tertiary units, the Crater Pasture Formation and the Fort Rock Creek Rhyodacite, are named. A mathematical model of the doming process is developed that is consistent with the history of the Fort Rock Dome.

  7. Supernovae and solar cycles embedded in a Dome F ice core

    NASA Astrophysics Data System (ADS)

    Motizuki, Yuko; Naka, Yoichi; Takahashi, Kazuya

    2010-11-01

    We have recently found signals of candidates for two historical supernovae and past solar cycles in a depth profile of nitrate ion concentrations in an ice core portion corresponding to the 10th and the 11th centuries. This ice core was drilled in 2001 at Dome Fuji (Dome F) station in Antarctica. We briefly review our findings and discuss why Dome F is appropriate for this study.

  8. Method of estimating time scales of the atmospheric piston and its application at Dome C (Antarctica)

    SciTech Connect

    Kellerer, Aglae; Sarazin, Marc; Coude du Foresto, Vincent; Agabi, Karim; Aristidi, Eric; Sadibekova, Tatyana

    2006-08-01

    Analysis of the first interferometric fringes recorded at Dome C, Antarctica are presented. Measurements were taken 31 January and 1 February 2005 during daytime. Our purpose in performing the analysis was to measure temporal fluctuations of the atmospheric piston, which are critical for interferometers, and determine their sensitivity.These scales are derived through the motion of the image that is formed in the focal plane of a Fizeau interferometer.We could establish a lower limit to the coherence time by studying the decay rate of correlation between successive fringes. Coherence times are measured to be larger than 10 ms, i.e., at least three times higher than the median coherence time measured at the site of Paranal(3.3 ms)

  9. The effect of overburden thickness on tension fracture patterns above an uplifting dome

    NASA Technical Reports Server (NTRS)

    Pranger, H., II

    1987-01-01

    Four experiments demonstrate that tension-fracture patterns above an uplifting dome depend on the thickness of the overburden layer being deformed. Four layers of increasing thicknesses (4.92 cm, 6.92 cm, 9.05 cm, and 11.12 cm) of a very fine sand (85%) and silt-clay (15%) mixture were updomed by slowly inflating a 1.22 m-diameter circular rubber pillow. The upper 2 cm of each layer was wetted and air dried to make it brittle and susceptible to fracture. The fractures that formed during these experiments exhibited a continuum of patterns from dominantly arcuate to dominantly radial as the overburden thickness increased. However, fracture density remained constant in each case for a given amount of surface deformation.

  10. Method of estimating time scales of the atmospheric piston and its application at Dome C (Antarctica).

    PubMed

    Kellerer, Aglae; Sarazin, Marc; du Foresto, Vincent Coudé; Agabi, Karim; Aristidi, Eric; Sadibekova, Tatyana

    2006-08-01

    Analysis of the first interferometric fringes recorded at Dome C, Antarctica are presented. Measurements were taken 31 January and 1 February 2005 during daytime. Our purpose in performing the analysis was to measure temporal fluctuations of the atmospheric piston, which are critical for interferometers, and determine their sensitivity. These scales are derived through the motion of the image that is formed in the focal plane of a Fizeau interferometer. We could establish a lower limit to the coherence time by studying the decay rate of correlation between successive fringes. Coherence times are measured to be larger than 10 ms, i.e., at least three times higher than the median coherence time measured at the site of Paranal (3.3 ms).

  11. A Scalable and Modular Dome Illumination System for Scientific Microphotography on a Budget

    PubMed Central

    Kawada, Ricardo; Buffington, Matthew L.

    2016-01-01

    A scalable and modular LED illumination dome for microscopic scientific photography is described and illustrated, and methods for constructing such a dome are detailed. Dome illumination for insect specimens has become standard practice across the field of insect systematics, but many dome designs remain expensive and inflexible with respect to new LED technology. Further, a one-size-fits-all dome cannot accommodate the large breadth of insect size encountered in nature, forcing the photographer to adapt, in some cases, to a less than ideal dome design. The dome described here is scalable, as it is based on a isodecahedron, and the template for the dome is available as a downloaded file from the internet that can be printed on any printer, on the photographer’s choice of media. As a result, a photographer can afford, using this design, to produce a series of domes of various sizes and materials, and LED ring lights of various sizes and color temperatures, depending on the need. PMID:27138573

  12. Single Star Scidar first light from Dome C

    NASA Astrophysics Data System (ADS)

    Vernin, J.; Chadid-Vernin, M.; Aristidi, E.; Trinquet, H.; Sadibekova, T.

    2006-08-01

    Here, we present the SSS first light from Dome C Antarctica. Results obtained during Chadid's expedition in the Summer Season 2005-2006 . The alpha Car observations are obtained during the day and using a 40 cm telescope. The SSS "Single Star Scidar" technique derives from the so-called Scidar (SCIntillation Detection and Ranging) technique, which analyses the scintillation, on the entrance pupil of a telescope, of a double star. The scientific goal is to measure vertical profiles of the Optical Turbulence C_N ^2 (h) and the wind speed *V*(h) at Dome C from the scintillation of a single star. From those two profiles it is possible to deduce almost all the parameters which can help to optimize all the instruments devoted to High Angular Resolution Astronomy, such as Adaptive Optics and Interferometry. The SSS at Dome C is composed of a 40 cm telescope driven by an equatorial mount. A short focal lens is used to collimate the optical beam, and the defocussed image of the telescope pupil is acquired by a CCD. Several thousands of images are analyzed in real time to deliver spatio-temporal cross correlations. Each few tens of seconds, such a correlation is stored in order be processed off line with the "simulated annealing" method. The development and construction of this instrument was made possible with help of: Air Force Office of Scientific Research and the European Office of Aerospace Research and Development (USA), Programmes Internationaux de Cooperation Scientifique, INSU and CNRS contracts, a European "ELT Design Study" contract, the IPEV infrastructure and financing, AFRL-VSBYA (USA), IAC (Spain) and ANR "CASDOA" contract.

  13. Light, shadows and surface characteristics: the multispectral Portable Light Dome

    NASA Astrophysics Data System (ADS)

    Watteeuw, Lieve; Hameeuw, Hendrik; Vandermeulen, Bruno; Van der Perre, Athena; Boschloos, Vanessa; Delvaux, Luc; Proesmans, Marc; Van Bos, Marina; Van Gool, Luc

    2016-11-01

    A multispectral, multidirectional, portable and dome-shaped acquisition system is developed within the framework of the research projects RICH (KU Leuven) and EES (RMAH, Brussels) in collaboration with the ESAT-VISICS research group (KU Leuven). The multispectral Portable Light Dome (MS PLD) consists of a hemispherical structure, an overhead camera and LEDs emitting in five parts of the electromagnetic spectrum regularly covering the dome's inside surface. With the associated software solution, virtual relighting and enhancements can be applied in a real-time, interactive manner. The system extracts genuine 3D and shading information based on a photometric stereo algorithm. This innovative approach allows for instantaneous alternations between the computations in the infrared, red, green, blue and ultraviolet spectra. The MS PLD system has been tested for research ranging from medieval manuscript illuminations to ancient Egyptian artefacts. Preliminary results have shown that it documents and measures the 3D surface structure of objects, re-visualises underdrawings, faded pigments and inscriptions, and examines the MS results in combination with the actual relief characteristics of the physical object. Newly developed features are reflection maps and histograms, analytic visualisations of the reflection properties of all separate LEDs or selected areas. In its capacity as imaging technology, the system acts as a tool for the analysis of surface materials (e.g. identification of blue pigments, gold and metallic surfaces). Besides offering support in answering questions of attribution and monitoring changes and decay of materials, the PLD also contributes to the identification of materials, all essential factors when making decisions in the conservation protocol.

  14. Seafloor doming driven by active mantle degassing offshore Naples (Italy)

    NASA Astrophysics Data System (ADS)

    Ventura, Guido; Passaro, Salvatore; Tamburrino, Stella; Vallefuoco, Mattia; Tassi, Franco; Vaselli, Orlando; Giannini, Luciano; Caliro, Stefano; Chiodini, Giovanni; Sacchi, Marco; Rizzo, Andrea

    2016-04-01

    Structures and processes associated with shallow water hydrothermal fluid discharges on continental shelves are poorly known. We report geomorphological, geophysical, and geochemical evidences of a 5.5 x 5.3 km seabed doming located 5 km offshore the Naples harbor (Italy). The dome lies between 100 and 170 m of water depth and it is 15-20 m higher than the surrounding seafloor. It is characterized by a hummocky morphology due to 280 sub-circular to elliptical mounds, about 660 cones, and 30 pockmarks. The mounds and pockmarks alignments follow those of the main structural discontinuity affecting the Gulf of Naples. The seafloor swelling and breaching require relatively low pressures (about 2-3 MPa), and the sub-seafloor structures, which consists of 'pagodas' affecting the present-day seabed, record the active upraise, pressurization, and release of magmatic fluids. The gas composition of the sampled submarine emissions is consistent with that of the emissions from the hydrothermal systems of Ischia, CampiFlegrei and Somma-Vesuvius active volcanoes, and CO2 has a magmatic/thermometamorphic origin. The 3He/4He ratios (1.66-1.96 Ra) are slightly lower than in the Somma-Vesuvius and Campi Flegrei volcanoes (~2.6-3.0 Ra) indicating the contamination of fluids originated from the same magmatic source by crustal-derived radiogenic 4He. All these evidences concur to hypothesize an extended magmatic reservoir beneath Naples and its offshore. Seabed doming, faulting, and hydrothermal discharges are manifestations of non-volcanic unrests potentially preluding submarine eruptions and/or hydrothermal explosions. We conclude that seabed deformations and hydrothermal discharge must be included in the coastal hazard studies.

  15. Winter sky brightness & cloud cover over Dome A

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Moore, A. M.; Fu, J.; Ashley, M.; Cui, X.; Feng, L.; Gong, X.; Hu, Z.; Laurence, J.; LuongVan, D.; Riddle, R. L.; Shang, Z.; Sims, G.; Storey, J.; Tothill, N.; Travouillon, T.; Wang, L.; Yang, H.; Yang, J.; Zhou, X.; Zhu, Z.; Burton, M. G.

    2014-01-01

    At the summit of the Antarctic plateau, Dome A offers an intriguing location for future large scale optical astronomical Observatories. The Gattini DomeA project was created to measure the optical sky brightness and large area cloud cover of the winter-time sky above this high altitude Antarctic site. The wide field camera and multi-filter system was installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in January 2008. This automated wide field camera consists of an Apogee U4000 interline CCD coupled to a Nikon fish-eye lens enclosed in a heated container with glass window. The system contains a filter mechanism providing a suite of standard astronomical photometric filters (Bessell B, V, R), however, the absence of tracking systems, together with the ultra large field of view 85 degrees) and strong distortion have driven us to seek a unique way to build our data reduction pipeline. We present here the first measurements of sky brightness in the photometric B, V, and R band, cloud cover statistics measured during the 2009 winter season and an estimate of the transparency. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based location. A ~0.2 magnitude agreement of our simultaneous test at Palomar Observatory with NSBM(National Sky Brightness Monitor), as well as an 0.04 magnitude photometric accuracy for typical 6th magnitude stars limited by the instrument design, indicating we obtained reasonable results based on our ~7mm effective aperture fish-eye lens.

  16. 7-forming, superconducting filaments through bicomponent dry spinning

    DOEpatents

    Tuominen, Olli P.; Morgan, Carol W.; Burlone, Dominick A.; Blankenship, Keith V.

    2001-01-01

    Fibers which contain potentially superconducting material are dry spun by the steps of preparing a suspension of potentially superconducting powder in a thickened solvent; preparing a solution of fiber-forming polymer; supplying the suspension and the solution to a spinning apparatus; in the spinning apparatus, arranging the solution and the suspension in a bicomponent arrangement; extruding the arranged solution and suspension from a spinneret as a bicomponent filament; and removing the solvent from the filament.

  17. Domed Fresnel lens concentrator technology for space application

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F., Jr.; Oneill, Mark J.

    1989-01-01

    Over the past three years, NASA Lewis and Entech, Inc. have been investigating the use of high efficiency refractive photovoltaic concentrators for use in space. The design currently under investigation uses a square domed Fresnel lens to focus light on a GaAs concentrator cell. A prismatic cell cover, which directs light away from the front contacts and thus eliminates metalization losses, is applied to the top of the GaAs cell to further enhance array efficiency. The latest experimental results based on testing the GaAs cell/prism cover assembly at standard and operating conditions are presented.

  18. Static analysis of a sonar dome rubber window

    NASA Technical Reports Server (NTRS)

    Lai, J. L.

    1978-01-01

    The application of NASTRAN (level 16.0.1) to the static analysis of a sonar dome rubber window (SDRW) was demonstrated. The assessment of the conventional model (neglecting the enclosed fluid) for the stress analysis of the SDRW was made by comparing its results to those based on a sophisticated model (including the enclosed fluid). The fluid was modeled with isoparametric linear hexahedron elements with approximate material properties whose shear modulus was much smaller than its bulk modulus. The effect of the chosen material property for the fluid is discussed.

  19. Field Survey of Cactus Crater Storage Facility (Runit Dome)

    SciTech Connect

    Douglas Miller, Terence Holland

    2008-10-31

    The US Department of Energy, Office of Health and Safety (DOE/HS-10), requested that National Security Technologies, LLC, Environmental Management directorate (NSTec/EM) perform a field survey of the Cactus Crater Storage Facility (Runit Dome), similar to past surveys conducted at their request. This field survey was conducted in conjunction with a Lawrence Livermore National Laboratory (LLNL) mission on Runit Island in the Enewetak Atoll in the Republic of the Marshall Islands (RMI). The survey was strictly a visual survey, backed up by digital photos and a written description of the current condition.

  20. Photogrammetric monitoring of lava dome growth during the 2009 eruption of Redoubt Volcano

    NASA Astrophysics Data System (ADS)

    Diefenbach, Angela K.; Bull, Katharine F.; Wessels, Rick L.; McGimsey, Robert G.

    2013-06-01

    The 2009 eruption of Redoubt Volcano, Alaska, began with a phreatic explosion on 15 March followed by a series of at least 19 explosive events and growth and destruction of at least two, and likely three, lava domes between 22 March and 4 April. On 4 April explosive activity gave way to continuous lava effusion within the summit crater. We present an analysis of post-4 April lava dome growth using an oblique photogrammetry approach that provides a safe, rapid, and accurate means of measuring dome growth. Photogrammetric analyses of oblique digital images acquired during helicopter observation flights and fixed-wing volcanic gas surveys produced a series of digital elevation models (DEMs) of the lava dome from 16 April to 23 September. The DEMs were used to calculate estimates of volume and time-averaged extrusion rates and to quantify morphological changes during dome growth. Effusion rates ranged from a maximum of 35 m3 s- 1 during the initial two weeks to a low of 2.2 m3 s- 1 in early summer 2009. The average effusion rate from April to July was 9.5 m3 s- 1. Early, rapid dome growth was characterized by extrusion of blocky lava that spread laterally within the summit crater. In mid-to-late April the volume of the dome had reached 36 × 106 m3, roughly half of the total volume, and dome growth within the summit crater began to be limited by confining crater walls to the south, east, and west. Once the dome reached the steep, north-sloping gorge that breaches the crater, growth decreased to the south, but the dome continued to inflate and extend northward down the gorge. Effusion slowed during 16 April-1 May, but in early May the rate increased again. This rate increase was accompanied by a transition to exogenous dome growth. From mid-May to July the effusion rate consistently declined. The decrease is consistent with observations of reduced seismicity, gas emission, and thermal anomalies, as well as declining rates of geodetic deflation or inflation. These trends

  1. Measurement of air quality within storage domes in technical area 54, areas G and L

    SciTech Connect

    Anderson, E.

    1994-03-15

    The concentrations of volatile organic compounds (VOCs) and tritium inside of storage domes at TA-54 were measured to assess worker exposure and support the Area G site characterization, including the Radioactive Air Emissions Management (RAEM) program. Samples were collected at 2-3 locations within Domes 48, 49, and 153 on up to six days during the summer of 1994. Samples were collected to evaluate three scenarios: (1) normal working activities with the domes open; (2) after domes were closed overnight; and (3) after domes were closed for three days. Eight-hour integrated samples were collected and analyzed in Radian`s Austin laboratories. Tritium activities from 17.1 to 69,900 pCi/m{sup 3} were measured. About two dozen individual VOCs were identified in each sample, but most of the concentration levels were very low (e.g.; < 1 to 10 ppbv). The highest concentrations measured were bromomethane (56.5 ppbv), 1, 1,1-trichloroethane (75.4 ppbv), propane (958 ppbv), methylene chloride (1,450 ppbv), and toluene (22.8). The measured VOC concentrations were well below the action levels developed by the New Mexico Environment Department and the measured tritium concentrations were well below the DOE`s derived air concentration (DAC). The variability in concentration within a dome during a single sampling episode was small. The concentrations were about an order of magnitude (i.e., 10x) higher after the domes had been closed overnight compared with the domes when open. Closing the domes over the weekend did not result in significantly higher concentrations (e.g.; > 20%) than when the domes were closed only overnight. The data were used to generate estimated annual dome emission rates of 0.3 Ci/yr of tritium and less than 100 lbs/yr of VOCs. The measured VOC concentrations were collected during the warmest months of the year and therefore should represent worst-case air impacts.

  2. The use of digital periapical radiographs to study the prevalence of alveolar domes

    PubMed Central

    Xambre, Pedro Augusto Oliveira Santos; Valerio, Claudia Scigliano; e Alves Cardoso, Claudia Assunção; Custódio, Antônio Luís Neto

    2016-01-01

    Purpose In the present study, we coined the term 'alveolar dome' and aimed to demonstrate the prevalence of alveolar domes through digital periapical radiographs. Materials and Methods This study examined 800 digital periapical radiographs in regard to the presence of alveolar domes. The periapical radiographs were acquired by a digital system using a photostimulable phosphor (PSP) plate. The χ2 test, with a significance level of 5%, was used to compare the prevalence of alveolar domes in the maxillary posterior teeth and, considering the same teeth, to verify the difference in the prevalence of dome-shaped phenomena between the roots. Results The prevalence of alveolar domes present in the first pre-molars was statistically lower as compared to the other maxillary posterior teeth (p<0.05). No statistically significant difference was observed in the prevalence of alveolar domes between the maxillary first and second molars. Considering the maxillary first and second molars, it was observed that the palatal root presented a lower prevalence of alveolar domes when compared to the distobuccal and mesiobuccal roots (p<0.05). Conclusion The present study coined the term 'alveolar dome', referring to the anatomical projection of the root into the floor of the maxillary sinus. The maxillary first and second molars presented a greater prevalence of alveolar domes, especially in the buccal roots, followed by the third molars and second pre-molars. Although the periapical radiograph is a two-dimensional method, it can provide dentists with the auxiliary information necessary to identify alveolar domes, thus improving diagnosis, planning, and treatment. PMID:27672614

  3. Middle Proterozoic uplift events in the Dunbar dome of northeastern Wisconsin, USA

    USGS Publications Warehouse

    Peterman, Z.E.; Sims, P.K.; Zartman, R.E.; Schulz, K.J.

    1985-01-01

    Isotopic ages of granitic and metamorphic rocks exposed in the Dunbar structural dome of northeastern Wisconsin identify a protracted series of tectonic and "hydrothermal" events that culminated in major regional uplift during Middle Proterozoic (Keweenawan; ca 1,100 Ma) continental rifting and volcanism. The major rock-forming events and the structural development of the dome occurred during the interval 1,862+/-4 Ma to 1,836+/-6 Ma. Whole-rock Rb-Sr ages are partly reset in response to a widely recognized but cryptic event in Wisconsin and Michigan at about 1,630 Ma. The scale and systematic character of the whole-rock resetting strongly suggests the presence of a fluid phase derived in situ from water dissolved in the silicates or externally from a subthrust plate of low-grade metamorphic rocks. The regional nature of the 1,630-Ma disturbance possibly indicates that it is related to a major tectonic event such as an active plate margin far to the south. Rb-Sr biotite ages for the Dunbar dome (this study), the southern complex of the Marquette district (Van Schmus and Woolsey 1975) and the Felch trough area (Aldrich and others 1965) provide a remarkably coherent pattern that reflects multiple episodes of differential uplift. Younger events superimposed on a regional 1,630-Ma imprint are recorded at 1,330 Ma and 1,140 Ma. The 1,330 Ma disturbance could reflect stabilization following intrusion of the Wolf River batholith at 1,485 Ma. The 1,140-Ma uplift event occurred during Keweenawan rifting and volcanism as a result of stresses imposed on a mosaic of fault-bounded blocks with possible subcrustal influence. The remarkably small variance in the 1,140-Ma biotite age peak argues for rapid uplift and cooling, and hence rapid erosion. Detritus from the uplift probably was being shed into nearby tectonic basins most of which did not survive subsequent uplift and erosion. ?? 1985 Springer-Verlag.

  4. Flat Versus Hemispherical Dome Ports in Underwater Photogrammetry

    NASA Astrophysics Data System (ADS)

    Menna, F.; Nocerino, E.; Remondino, F.

    2017-02-01

    Underwater photogrammetry, like its counterpart in 'air', has gained an increasing diffusion thanks to the availability of easy-to-use, fast and often quite inexpensive software applications. Moreover, underwater equipment that allows the use of digital cameras normally designed to work in air also in water are largely available. However, for assuring accurate and reliable 3D modelling results a profound knowledge of the employed devices as well as physical and geometric principle is even more crucial than in air. This study aims to take a step forward in understanding the effect of underwater ports in front of the photographic lens. In particular, the effect of dome or flat ports on image quality in 3D modelling applications is investigated. Experiments conducted in a semi submerged indust rial structure show that the tested flat port performs worse than the dome, providing higher image residuals and lower precision and accuracy in object space. A significant different quality per colour channel is also observed and its influence on achievable processing results is discussed.

  5. Dome shaped micro-laser encapsulated in a flexible film

    NASA Astrophysics Data System (ADS)

    Ioppolo, T.; Manzo, M.

    2014-11-01

    In this paper, we demonstrated multimode laser emission from a dome shaped micro-scale resonator encapsulated in a flexible polymer film. The resonator with a radius of ~60 microns was made of Norland Blocking Adhesive (NBA 107) doped with a solution of rhodamine 6G and ethanol. The dome was encapsulated in a flexible polymeric film made of polydymethylsiloxane (PDMS) with a thickness of 1 mm. The micro-scale laser was optically pumped using a frequency doubled Q-switch Nd:YAG laser with pulse repetition of 10 Hz and pulse duration of 9 ns. Experiments were carried out to investigate the lasing properties of this laser structure. The pumping threshold for multimode laser emission was below 100 µJ cm-2. The average optical quality factor for all observed laser modes was of the order of 104. Using a fluence of 315.8 µJ cm-2 it was observed that the intensity of the laser emission dropped by 62% after 5 min of operation. These results showed that these solid state flexible lasers are easy to fabricate and can be integrated into novel flexible photonic devices and novel photonic sensors.

  6. PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA

    SciTech Connect

    Wang Lingzhi; Macri, Lucas M.; Krisciunas, Kevin; Wang Lifan; Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Storey, John W. V.; Cui Xiangqun; Gong Xuefei; Yuan Xiangyan; Feng Longlong; Yang Ji; Zhu Zhenxi; Liu Qiang; Zhou Xu; Pennypacker, Carl R.; Shang Zhaohui; Yang Huigen; York, Donald G.

    2011-11-15

    Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i < 14.5 mag located in a 23 deg{sup 2} region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly uninterrupted synoptic coverage, we found six times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% were unclassified, 27% were likely binaries, and 17% were likely pulsating stars. The latter category includes {delta} Scuti, {gamma} Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.

  7. Exceptional astronomical seeing conditions above Dome C in Antarctica

    NASA Astrophysics Data System (ADS)

    Lawrence, Jon S.; Ashley, Michael C. B.; Tokovinin, Andrei; Travouillon, Tony

    2004-09-01

    One of the most important considerations when planning the next generation of ground-based optical astronomical telescopes is to choose a site that has excellent `seeing'-the jitter in the apparent position of a star that is caused by light bending as it passes through regions of differing refractive index in the Earth's atmosphere. The best mid-latitude sites have a median seeing ranging from 0.5 to 1.0arcsec (refs 1-5). Sites on the Antarctic plateau have unique atmospheric properties that make them worth investigating as potential observatory locations. Previous testing at the US Amundsen-Scott South Pole Station has, however, demonstrated poor seeing, averaging 1.8arcsec (refs 6, 7). Here we report observations of the wintertime seeing from Dome C (ref. 8), a high point on the Antarctic plateau at a latitude of 75° S. The results are remarkable: the median seeing is 0.27arcsec, and below 0.15arcsec 25 per cent of the time. A telescope placed at Dome C would compete with one that is 2 to 3 times larger at the best mid-latitude observatories, and an interferometer based at this site could work on projects that would otherwise require a space mission.

  8. COBBER: A Pocket Cloud Detector for Dome C

    NASA Astrophysics Data System (ADS)

    Dempsey, J. T.; Storey, J. W. V.; Ashley, M. C. B.

    COBBER (ClOud OBservER), is a mid-infrared sky monitor featuring a 10mu m Perkin-Elmer TPS534 thermopile detector. Radiation is focussed on to the detector through an anti-reflection coated, hemispherical ZnSe lens, providing a 30o field of view on the sky. At 10cm in length and 4cm diameter, the tiny cloud monitor was designed for ease of transportation and an extremely low power budget. Run in conjunction with ICECAM, it uses power supplied by lithium thionyl chloride (LiSOCl_2) batteries. COBBER is powered up by the ICECAM system once every two hours, sending its data to Sydney via the ARGOS satellite link. The instrument was installed at Dome C in January of 2003, and has been collecting data continuously from this date. In over 70 observing days, only four days of cloud have been recorded, results which have been confirmed by a webcamera installed at Dome C as part of the AASTINO project.

  9. Sealing considerations for repository shafts in bedded and dome salt

    NASA Astrophysics Data System (ADS)

    1981-12-01

    The geologic and hydrologic data base is reviewed for penetration seal designs referenced to the Los Medanos bedded salt site in New Mexico and to four candidate salt domes in the Gulf Interior. Experience with existing shafts highlights the importance, for shaft decommissioning as well as operation, of achieving an adequate seal at and immediately below the top of salt. Possible constuction procedures for repository shafts are reviewed, noting advantages and disadvantages with respect to repository sealing. At this stage, there does not appear to be a clear preference for excavation by drill and blast or by drilling. If conventional drill and blast methods are used, it may be necessary to grout in permeable zones above the salt. An important consideration with respect to sealing is that grouting operations (or freezing should it be used) should not establish connections between the top of salt and waterbearing zones higher in the stratigraphic section. Generally, it is concluded that Los Medanos and the dome salt sites are favorable candidate repository sites from the point of view of sealing.

  10. Exceptional astronomical seeing conditions above Dome C in Antarctica.

    PubMed

    Lawrence, Jon S; Ashley, Michael C B; Tokovinin, Andrei; Travouillon, Tony

    2004-09-16

    One of the most important considerations when planning the next generation of ground-based optical astronomical telescopes is to choose a site that has excellent 'seeing'--the jitter in the apparent position of a star that is caused by light bending as it passes through regions of differing refractive index in the Earth's atmosphere. The best mid-latitude sites have a median seeing ranging from 0.5 to 1.0 arcsec (refs 1-5). Sites on the Antarctic plateau have unique atmospheric properties that make them worth investigating as potential observatory locations. Previous testing at the US Amundsen-Scott South Pole Station has, however, demonstrated poor seeing, averaging 1.8 arcsec (refs 6, 7). Here we report observations of the wintertime seeing from Dome C (ref. 8), a high point on the Antarctic plateau at a latitude of 75 degrees S. The results are remarkable: the median seeing is 0.27 arcsec, and below 0.15 arcsec 25 per cent of the time. A telescope placed at Dome C would compete with one that is 2 to 3 times larger at the best mid-latitude observatories, and an interferometer based at this site could work on projects that would otherwise require a space mission.

  11. Seismic measurements of explosions in the Tatum Salt Dome, Mississippi

    USGS Publications Warehouse

    Borcherdt, Roger D.; Healy, J.H.; Jackson, W.H.; Warren, D.R.

    1967-01-01

    Project Sterling provided for the detonation of a nuclear device in the cavity resulting from the Salmon nuclear explosion in the Tatum salt dome in southern Mississippi. It also provided for a high explosive (HE) comparison shot in a nearby drill hole. The purpose of the experiment was to gather information on the seismic decoupling of a nuclear explosion in a cavity by comparing seismic signals from a nuclear shot in the Salmon cavity with seismic signals recorded from Salmon and with seismic signals recorded from a muall (about 2 tons) HE shot in the salt dome. Surface seismic measurements were made by the U.S. Geological Survey, the U.S. Coast and Geodetic Survey, and the Air Force Technical Applications Center with coordination and overall direction by the Lawrence Radiation Laboratory. This report covers only the seismic measurements made by the U. S. Geological Survey. The first objective of this report is to describe the field recording procedures and the data obtained by the U. S. Geological Survey from these events. The second objective is to describe the spectral analyses which have been made on the data and the relative seismic amplitudes which have been determined from these analyses.

  12. Nonlinear vibration of a hemispherical dome under external water pressure

    NASA Astrophysics Data System (ADS)

    Ross, C. T. F.; McLennan, A.; Little, A. P. F.

    2011-07-01

    The aim of this study was to analyse the behaviour of a hemi-spherical dome when vibrated under external water pressure, using the commercial computer package ANSYS 11.0. In order to achieve this aim, the dome was modelled and vibrated in air and then in water, before finally being vibrated under external water pressure. The results collected during each of the analyses were compared to the previous studies, and this demonstrated that ANSYS was a suitable program and produced accurate results for this type of analysis, together with excellent graphical displays. The analysis under external water pressure, clearly demonstrated that as external water pressure was increased, the resonant frequencies decreased and a type of dynamic buckling became likely; because the static buckling eigenmode was similar to the vibration eigenmode. ANSYS compared favourably with the in-house software, but had the advantage that it produced graphical displays. This also led to the identification of previously undetected meridional modes of vibration; which were not detected with the in-house software.

  13. Electrochemical properties of melt spun Si-Cu-Ti-Zr-Ni alloy powders for the anode of Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Bae, Seong Min; Sohn, Keun Yong; Park, Won-Wook

    2014-07-01

    The Si-Cu-Ti-Zr-Ni alloys of various compositions were prepared using arc-melting under an argon atmosphere, and the alloys were re-melted several times to ensure chemical homogeneity. The alloyed ingots were melt-spun to produce rapidly solidified ribbons under vacuum in order to prevent oxidation. Finely dispersed silicon particles 50-100 nm in diameter mainly consisting of Cu3Si, NiSi2 and TiSi2 phases were formed in the matrices. The alloy ribbons were then fragmented using ball-milling to produce powders. In order to evaluate the electrochemical properties of the alloys, anode electrodes were fabricated by mixing the active alloy materials (80 wt. %) with Ketjenblack® (2 wt. %) as a conductive material and polyamide imide (PAI, 8 wt. %) binder, and the mixtures were dissolved in N-methyl-2-pyrrolidinone (NMP) and SFG6 (10 wt. %). The anode performances of Si-Cu-Ti-Zr-Ni alloy cells were measured in the range 0.01-1.5 V (versus Li/Li+). The results showed that the Si68(Cu47Ti34Zr11Ni8)32 alloy ribbons had the highest specific discharge capacities, and the Si68(Cu40Ti40Zr10Ni10)32 alloy ribbons had relatively stable electrochemical properties and cycle performances due to the very fine microstructure including partially distributed amorphous phase. The matrix phases of the Si-Cu-Ti-Zr-Ni alloy ribbons effectively accommodated the change in Si particle volume during cycling.

  14. Effect of microstructure and texture on the magnetic and magnetocaloric properties of the melt-spun rare earth intermetallic compound DyNi

    NASA Astrophysics Data System (ADS)

    Rajivgandhi, R.; Chelvane, J. Arout; Nigam, A. K.; Park, Je-Geun; Malik, S. K.; Nirmala, R.

    2016-11-01

    Magnetization measurements have been carried out on the melt-spun ribbon sample of the rare earth intermetallic compound DyNi (Orthorhombic, FeB-type, Space group Pnma) and its magnetic and magnetocaloric properties are compared with those of the arc-melted analog. The arc-melted DyNi orders ferromagnetically at around 61 K (TC) whereas the melt-spun DyNi orders ferromagnetically at about 47 K. The maximum isothermal magnetic entropy change, ∆Smmax , near TC of the arc-melted and the melt-spun DyNi is found to be -32.7 J/kg K and -22.4 J/kg K, respectively, for a field change of 140 kOe. For low magnetic field changes of ~20 kOe, the relative cooling power (RCP) is ~660 J/kg for the arc melted DyNi and ~460 J/kg for the melt-spun ribbon. The reduction in TC and magnetocaloric effect may be attributed to the microstructure-induced anisotropy developed during the melt-spinning process.

  15. Teapot Dome: Site Characterization of a CO2- Enhanced Oil Recovery Site in Eastern Wyoming

    SciTech Connect

    Friedmann, S J; Stamp, V

    2005-11-01

    Naval Petroleum Reserve No. 3 (NPR-3), better known as the Teapot Dome oil field, is the last U.S. federally-owned and -operated oil field. This provides a unique opportunity for experiments to provide scientific and technical insight into CO{sub 2}-enhanced oil recovery (EOR) and other topics involving subsurface fluid behavior. Towards that end, a combination of federal, academic, and industrial support has produced outstanding characterizations of important oil- and brine-bearing reservoirs there. This effort provides an unparalleled opportunity for industry and others to use the site. Data sets include geological, geophysical, geochemical, geomechanical, and operational data over a wide range of geological boundary conditions. Importantly, these data, many in digital form, are available in the public domain due to NPR-3's federal status. Many institutions are already using portions of the Teapot Dome data set as the basis for a variety of geoscience, modeling, and other research efforts. Fifteen units, 9 oil-bearing and 6 brine-bearing, have been studied to varying degrees. Over 1200 wells in the field are active or accessible, and over 400 of these penetrate 11 formations located below the depth that corresponds to the supercritical point for CO{sub 2}. Studies include siliciclastic and carbonate reservoirs; shale, carbonate, and anhydrite cap rocks; fractured and unfractured units; and over-pressured and under-pressured zones. Geophysical data include 3D seismic and vertical seismic profiles. Reservoir data include stratigraphic, sedimentological, petrologic, petrographic, porosity, and permeability data. These have served as the basis for preliminary 3D flow simulations. Geomechanical data include fractures (natural and drilling induced), in-situ stress determination, pressure, and production history. Geochemical data include soil gas, noble gas, organic, and other measures. The conditions of these reservoirs directly or indirectly represent many reservoirs

  16. Rift-related volcanism and karst geohydrology of the southern Ozark Dome

    USGS Publications Warehouse

    Harrison, Richard W.; Weary, David J.; Orndorff, Randall C.; Repetski, John E.; Pierce, Herbert A.; Lowell, Gary R.; Evans, Kevin R.; Aber, James S.

    2010-01-01

    This field trip examines the geology and geohydrology of a dissected part of the Salem Plateau in the Ozark Plateaus province of south-central Missouri. Rocks exposed in this area include karstified, flat-lying, lower Paleozoic carbonate platform rocks deposited on Mesoproterozoic basement. The latter is exposed as an uplift located about 40 mi southwest of the St. Francois Mountains and form the core of the Ozark dome. On day 1, participants will examine and explore major karst features developed in Paleozoic carbonate strata on the Current River; this will include Devil's Well and Round Spring Cavern as well as Montauk, Round, Alley, and Big Springs. The average discharge of the latter is 276 × 106 gpd and is rated in the top 20 springs in the world. Another, Alley Spring, is equally spectacular with an average discharge of 81 × 106 gpd. Both are major contributors to the Current and Eleven Point River drainage system which includes about 50 Mesoproterozoic volcanic knobs and two granite outcrops. These knobs are mainly caldera-erupted ignimbrites with a total thickness of 7–8 km. They are overlain by post-collapse lavas and intruded by domes dated at 1470 Ma. Volcaniclastic sediment and air-fall lapilli tuff are widely distributed along this synvolcanic unconformity. On day 2, the group will examine the most important volcanic features and the southernmost granite exposure in Missouri. The trip concludes with a discussion of the Missouri Gravity Low, the Eminence caldera, and the volcanic history of southern Missouri as well as a discussion of geologic controls on regional groundwater flow through this part of the Ozark aquifer.

  17. Structural Optimization of the Retractable Dome for Four Meter Telescope (FMT)

    NASA Astrophysics Data System (ADS)

    Pan, Nian; Li, Yuxi; Fan, Yue; Ma, Wenli; Huang, Jinlong; Jiang, Ping; Kong, Sijie

    2017-03-01

    Dome seeing degrades the image quality of ground-based telescopes. To achieve dome seeing of the Four Meter Telescope (FMT) less than 0.5 arcsec, structural optimizations based on computational fluid dynamics (CFD) simulation were proposed. The results of the simulation showed that dome seeing of FMT was 0.42 arcsec, which was mainly caused by the slope angle of the dome when the slope angle was 15° and the wind speed was 10 m/s. Furthermore, the lower the air speed was, the less dome seeing would be. Wind tunnel tests (WT) with a 1:120 scaled model of the retractable dome and FMT indicated that the calculated deviations of the CFD simulation used in this paper were less than 20% and the same variations of the refractive index derived from the WT would be a convincing argument for the validity of the simulations. Thus, the optimization of the retractable dome was reliable and the method expressed in this paper provided a reference for the design of next generation of ground-based telescope dome.

  18. The ongoing dome emplacement and destruction cyclic process at Popocatépetl volcano, Central Mexico

    NASA Astrophysics Data System (ADS)

    Gómez-Vazquez, Angel; De la Cruz-Reyna, Servando; Mendoza-Rosas, Ana Teresa

    2016-09-01

    The ongoing eruptive activity of Popocatépetl volcano has been characterized by emplacement and subsequent destruction of a succession of lava domes. Between the onset of the current eruption in 1994 and the time of this submission, 38 episodes of lava dome formation and removal have been identified. Each dome has showed particular features related to the magma extrusion process. Among other manifestations, dome-emplacement events have been usually accompanied by relatively low-intensity, protracted explosions referred to as exhalations. After variable times of residence, emplacements have ended in partial or total destruction of the domes by strong vulcanian explosions that produced sizeable ash plumes, with most of them also ejecting incandescent debris onto the volcano flanks. Here, we present a detailed account for the observed activity related to the domes' growth and destruction, related seismic monitoring signals, and morphological features of the domes based on 19 years of visual observations and image analysis. We then discuss a model for the process of dome growth and destruction and its hazard implications.

  19. Salt domes: is there more energy available from their salt than from their oil?

    PubMed

    Wick, G L; Isaacs, J D

    1978-03-31

    Calculations indicate that a typical oil-bearing salt dome along the Gulf Coast of the United States contains more energy in its salt than is present in its oil. The magnitude of the potential salinity gradient energy is even greater when all of the salt domes are considered.

  20. A novel nonintrusive method to resolve the thermal dome effect of pyranometers: Instrumentation and observational basis

    NASA Astrophysics Data System (ADS)

    Ji, Qiang; Tsay, Si-Chee

    2010-04-01

    A new method for improving the ground-based pyranometer measurements of solar irradiance has been employed during the East Asian Study of Tropospheric Aerosols and Impact on Regional Climate field experiment, Asian Monsoon Year in China in 2008. Depending on the temperature difference between its detector and domes, a pyranometer's thermal dome effect (TDE) can vary from a few W m-2 at night to over tens of W m-2 during daytime. Yet in traditional calibration procedures only a single calibration constant is determined, and consequently TDE is misrepresented. None of the methods that have been documented in the literature can capture TDE nonintrusively using the same instrument. For example, although adding a temperature sensor to the detector assembly is straightforward, attaching any sensor on a dome is intrusive and will affect its overall optical and physical properties. Furthermore, in response to the solar elevation and atmospheric variables, the dome temperature distribution is both dynamic and uneven, which makes it exceedingly difficult for locating a representative point on the dome for measuring TDE. However, the effective-dome-temperature is proportional to the pressure of the air trapped between the outer and the inner domes; therefore with a minor modification to a pyranometer, we can utilize the ideal gas law to gauge TDE without affecting the domes. Pyranometers can become climate-quality instruments once their TDE are nonintrusively determined.

  1. LOFT, TAN650. Interior, camera faces upward toward apex of dome. ...

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

    LOFT, TAN-650. Interior, camera faces upward toward apex of dome. Bridge crane rides circular rail placed at tangent where dome meets wall. Date: May 2004. INEEL negative no. HD-39-18-3 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  2. Giant magnetocaloric effect in melt-spun Ni-Mn-Ga ribbons with magneto-multistructural transformation

    NASA Astrophysics Data System (ADS)

    Li, Zongbin; Zhang, Yudong; Sánchez-Valdés, C. F.; Sánchez Llamazares, J. L.; Esling, Claude; Zhao, Xiang; Zuo, Liang

    2014-01-01

    Magnetic refrigeration based on the magnetocaloric effect (MCE) may provide an energy-efficient and environment-friendly alternative to the conventional gas compression/expansion cooling technology. For potential applications, low-cost and high-performance magnetic refrigerants are in great need. Here, we demonstrate that giant MCE can be achieved in annealed Ni52Mn26Ga22 ribbons with magneto-multistructural transformation. It yields a maximum magnetic entropy change of -30.0 J kg-1 K-1 at the magnetic field change of 5 T, being almost three times as that of initial melt-spun ribbons and comparable to or even superior to that of polycrystalline bulk alloys.

  3. E-spun composite fibers of collagen and dragline silk protein: fiber mechanics, biocompatibility, and application in stem cell differentiation.

    PubMed

    Zhu, Bofan; Li, Wen; Lewis, Randolph V; Segre, Carlo U; Wang, Rong

    2015-01-12

    Biocomposite matrices with high mechanical strength, high stability, and the ability to direct matrix-specific stem cell differentiation are essential for the reconstruction of lesioned tissues in tissue engineering and cell therapeutics. Toward this end, we used the electrospinning technique to fabricate well-aligned composite fibers from collagen and spider dragline silk protein, obtained from the milk of transgenic goats, mimicking the native extracellular matrix (ECM) on a similar scale. Collagen and the dragline silk proteins were found to mix homogeneously at all ratios in the electrospun (E-spun) fibers. As a result, the ultimate tensile strength and elasticity of the fibers increased monotonically with silk percentage, whereas the stretchability was slightly reduced. Strikingly, we found that the incorporation of silk proteins to collagen dramatically increased the matrix stability against excessive fiber swelling and shape deformation in cell culture medium. When human decidua parietalis placental stem cells (hdpPSCs) were seeded on the collagen-silk matrices, the matrices were found to support cell proliferation at a similar rate as that of the pure collagen matrix, but they provided cell adhesion with reduced strengths and induced cell polarization at varied levels. Matrices containing 15 and 30 wt % silk in collagen (CS15, CS30) were found to induce a level of neural differentiation comparable to that of pure collagen. In particular, CS15 matrix induced the highest extent of cell polarization and promoted the development of extended 1D neural filaments strictly in-line with the aligned fibers. Taking the increased mechanical strength and fiber stability into consideration, CS15 and CS30 E-spun fibers offer better alternatives to pure collagen fibers as scaffolds that can be potentially utilized in neural tissue repair and the development of future nanobiodevices.

  4. Sensitivity of storage field performance to geologic and cavern design parameters in salt domes.

    SciTech Connect

    Ehgartner, Brian L.; Park, Byoung Yoon

    2009-03-01

    A sensitivity study was performed utilizing a three dimensional finite element model to assess allowable cavern field sizes for strategic petroleum reserve salt domes. A potential exists for tensile fracturing and dilatancy damage to salt that can compromise the integrity of a cavern field in situations where high extraction ratios exist. The effects of salt creep rate, depth of salt dome top, dome size, caprock thickness, elastic moduli of caprock and surrounding rock, lateral stress ratio of surrounding rock, cavern size, depth of cavern, and number of caverns are examined numerically. As a result, a correlation table between the parameters and the impact on the performance of storage field was established. In general, slower salt creep rates, deeper depth of salt dome top, larger elastic moduli of caprock and surrounding rock, and a smaller radius of cavern are better for structural performance of the salt dome.

  5. A structural outline of the Yenkahe volcanic resurgent dome (Tanna Island, Vanuatu Arc, South Pacific)

    NASA Astrophysics Data System (ADS)

    Merle, O.; Brothelande, E.; Lénat, J.-F.; Bachèlery, P.; Garaébiti, E.

    2013-12-01

    A structural study has been conducted on the resurgent Yenkahe dome (5 km long by 3 km wide) located in the heart of the Siwi caldera of Tanna Island (Vanuatu arc, south Pacific). This spectacular resurgent dome hosts a small caldera and a very active strombolian cinder cone - the Yasur volcano - in the west and exhibits an intriguing graben in its central part. Detailed mapping and structural observations make it possible to unravel the volcano-tectonic history of the dome. It is shown that, following the early formation of a resurgent dome in the west, a complex collapse (caldera plus graben) occurred and this was associated with the recent uplift of the eastern part of the present dome. Eastward migration of the underlying magma related to regional tectonics is proposed to explain this evolution.

  6. Strategic Petroleum Reserve (SPR) geological site characterization report, Big Hill Salt Dome

    SciTech Connect

    Hart, R.J.; Ortiz, T.S.; Magorian, T.R.

    1981-09-01

    Geological and geophysical analyses of the Big Hill Salt Dome were performed to determine the suitability of this site for use in the Strategic Petroleum Reserve (SPR). Development of 140 million barrels (MMB) of storage capacity in the Big Hill Salt Dome is planned as part of the SPR expansion to achieve 750 MMB of storage capacity. Objectives of the study were to: (1) Acquire, evaluate, and interpret existing data pertinent to geological characterization of the Big Hill Dome; (2) Characterize the surface and near-surface geology and hydrology; (3) Characterize the geology and hydrology of the overlying cap rock; (4) Define the geometry and geology of the dome; (5) Determine the feasibility of locating and constructing 14 10-MMB storage caverns in the south portion of the dome; and (6) Assess the effects of natural hazards on the SPR site. Recommendations are included. (DMC)

  7. Venusian pancake domes: Insights from terrestrial voluminous silicic lavas and thermal modeling

    NASA Technical Reports Server (NTRS)

    Manley, Curtis R.

    1993-01-01

    The so-called 'pancake' domes, and several other volcanoes on Venus, appear to represent large extrusions of silicic lava. Similar voluminous rhyolite lava flows, often associated with mantle plumes, are known on Earth. Venus' high ambient temperature, and insulation by the dome's brecciated carapace, both act to prolong cooling of a dome's interior, allowing for episodic lava input over an extended period of time. Field relations and aspect ratios of terrestrial voluminous rhyolite lavas imply continuous, non-episodic growth, reflecting tapping of a large volume of dry, anatectic silicic magma. Petrogenetically, the venusian domes may be analogous to chains of small domes on Earth, which represent 'leakage' of evolved material from magma bodies fractionating from much more mafic liquids.

  8. Design and test of an airborne IR countermeasures hyper-hemispherical silicon dome

    NASA Astrophysics Data System (ADS)

    Bender, Michael J.; Guyer, Robert C.; Fenton, Thomas E.

    2007-09-01

    A 6.5 inch diameter hyper-hemispherical silicon dome was developed on IRAD for an infrared countermeasures aircraft self-protection system. Having passed operational level environmental testing and many hours of flight performance, a prototype dome was subjected to MIL test requirements in simulated crash safety testing at the manufacturer's facility. Although the dome cracked during shock testing, it remained intact preserving aircraft integrity and actually passing safety requirements. This paper describes design requirements, stress analyses of the dome and its mounting, and test results including a forensic cause of failure study of the dome. The results add insight to the margins of safety normally applied to the stress analyses of brittle optical materials and examine actual cause of failure in the prototype part.

  9. New Contributions on the Dome of the Pantheon in Rome: Comparison Between the Ideal Model and the Survey Model

    NASA Astrophysics Data System (ADS)

    Aliberti, L.; Canciani, M.; Alonso Rodriguéz, M. A.

    2015-02-01

    This work proposes an integrated survey and a study of the intrados of the dome of the Pantheon in Rome. An actualized architectural survey of the interior of the dome can generate useful material for future studies. The survey has been realized by using in a first stage the digital photogrammetry and in a second stage the three-dimensional laser scan technology. The compared analysis between different methods applied in the same object is useful towards a closer approximation to real dimension. Among several aspects that arise in dealing with the Pantheon this work focuses mainly on the study of the geometry of the inner surface of the dome. The specific goal of the research is to verify the spherical form of the surface and the coffers' distribution. In this sense it takes an important place the extracting data system. In order to realize the analysis it was applied a critical treatment of selected information contained in the point cloud. The use of plan and section drawings connects to the study of three dimensional models. The research is based on the construction of an ideal geometrical model that derives from the theoretical model described in the historical documents. The survey points model, which keeps the irregularities of the actual form, determines the creation of an average sphere, that is a regular model defined by clarifying geometrical laws. The direct comparison between the survey model and the ideal model contributes to the building understanding. It detects irregularities or deformities where they exist, and provides objective and quantifiable data.

  10. Tectonic uplift mechanism of the Goodenough and Fergusson Island gneiss domes, eastern Papua New Guinea: Constraints from seismic reflection and well data

    NASA Astrophysics Data System (ADS)

    Fitz, Guy; Mann, Paul

    2013-10-01

    The D'Entrecasteaux Island (DEI) gneiss domes are fault-bounded domes with ˜2.5 km of relief exposing ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic gneisses and migmatites exhumed in an Oligocene-Miocene arc-continent collision and subduction zone subject to Late Miocene to Recent continental extension. To study the style of continental extension accompanying exhumation of the DEI gneiss domes, a grid of 1518 km of 2-D multichannel seismic (MCS) reflection data and well data is interpreted from the offshore areas surrounding the DEI, including the Trobriand basin and the Goodenough basin. The offshore study is combined with onshore geologic information to constrain the Oligocene to Recent tectonic evolution of the basins. MCS and well data are consistent with the Trobriand basin forming as a forearc basin caused by southward Miocene subduction at the Trobriand trench. At ˜8 Ma, the margin transitioned to an extensional tectonic environment. Since then, the Trobriand basin has subsided 1-2.5 km with few normal faults deforming the basin fill. South of the DEI, the Goodenough rift basin developed after extension began (˜8 Ma) with the hanging wall of the north-dipping Owen-Stanley normal fault bounding the southern margin of the basin. The lack of evidence of upper crustal extension accompanying subsidence in the Trobriand and Goodenough basins suggests depth-dependent lithospheric extension from 8 to 0 Ma has accompanied uplift of the DEI gneiss domes and supports schematic model of uplift of the DEI domes involving vertical exhumation of buoyant, postorogenic lower crust, far-field extension from slab rollback, and an inverted two-layer crustal density structure.

  11. Citronelle Dome: A giant opportunity for multizone carbon storage and enhanced oil recovery in the Mississippi Interior Salt Basin of Alabama

    USGS Publications Warehouse

    Esposito, R.A.; Pashin, J.C.; Walsh, P.M.

    2008-01-01

    The Citronelle Dome is a giant, salt-cored anticline in the eastern Mississippi Interior Salt Basin of southern Alabama that is located near several large-scale, stationary, carbon-emitting sources in the greater Mobile area. The dome forms an elliptical, four-way structural closure containing opportunities for CO2-enhanced oil recovery (CO2-EOR) and large-capacity saline reservoir CO2 sequestration. The Citronelle oil field, located on the crest of the dome, has produced more than 169 million bbl of 42-46?? API gravity oil from sandstone bodies in the Lower Cretaceous Rodessa Formation. The top seal for the oil accumulation is a thick succession of shale and anhydrite, and the reservoir is underfilled such that oil-water contacts are typically elevated 30-60 m (100-200 ft) above the structural spill point. Approximately 31-34% of the original oil in place has been recovered by primary and secondary methods, and CO2-EOR has the potential to increase reserves by up to 20%. Structural contour maps of the dome demonstrate that the area of structural closure increases upward in section. Sandstone units providing prospective carbon sinks include the Massive and Pilot sands of the lower Tuscaloosa Group, as well as several sandstone units in the upper Tuscaloosa Group and the Eutaw Formation. Many of these sandstone units are characterized by high porosity and permeability with low heterogeneity. The Tuscaloosa-Eutaw interval is capped by up to 610 m (2000 ft) of chalk and marine shale that are proven reservoir seals in nearby oil fields. Therefore, the Citronelle Dome can be considered a major geologic sink where CO2 can be safely stored while realizing the economic benefits associated with CO2-EOR. Copyright ?? 2008. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

  12. Crestal fault geometries reveal late halokinesis and collapse of the Samson Dome, Northern Norway: Implications for petroleum systems in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Mattos, Nathalia H.; Alves, Tiago M.; Omosanya, Kamaldeen O.

    2016-10-01

    This paper uses 2D and high-quality 3D seismic reflection data to assess the geometry and kinematics of the Samson Dome, offshore Norway, revising the implications of the new data to hydrocarbon exploration in the Barents Sea. The study area was divided into three (3) zones in terms of fault geometries and predominant strikes. Displacement-length (D-x) and Throw-depth (T-z) plots showed faults to consist of several segments that were later dip-linked. Interpreted faults were categorised into three families, with Type A comprising crestal faults, Type B representing large E-W faults, and Type C consisting of polygonal faults. The Samson Dome was formed in three major stages: a) a first stage recording buckling of the post-salt overburden and generation of radial faults; b) a second stage involving dissolution and collapse of the dome, causing subsidence of the overburden and linkage of initially isolated fault segments; and c) a final stage in which large fault segments were developed. Late Cretaceous faults strike predominantly to the NW, whereas NE-trending faults comprise Triassic structures that were reactivated in a later stage. Our work provides scarce evidence for the escape of hydrocarbons in the Samson Dome. In addition, fault analyses based on present-day stress distributions indicate a tendency for 'locking' of faults at depth, with the largest leakage factors occurring close to the surface. The Samson Dome is an analogue to salt structures in the Barents Sea where oil and gas exploration has occurred with varied degrees of success.

  13. Attenuation of acoustic waves in glacial ice and salt domes

    NASA Astrophysics Data System (ADS)

    Price, P. B.

    2006-02-01

    Two classes of natural solid media, glacial ice and salt domes, are under consideration as media in which to deploy instruments for detection of neutrinos with energy ≥1018 eV. Though insensitive to 1011 to 1016 eV neutrinos for which observatories (e.g., AMANDA and IceCube) that utilize optical Cherenkov radiation detectors are designed, radio and acoustic methods are suited for searches for the very low fluxes of neutrinos with energies >1017 eV. This is because owing to the very long attenuation lengths of radio and acoustic waves produced by interactions of such neutrinos in ice and salt, detection modules can be spaced at horizontal distances ˜1 km, in contrast to the 0.12 km distances between strings of IceCube modules. In this paper, I calculate the absorption and scattering coefficients as a function of frequency and grain size for acoustic waves in glacial ice and salt domes and show that experimental measurements on laboratory samples and in glacial ice and salt domes are consistent with theory. For South Pole ice with grain size ˜0.2 cm at depths ≤600 m, scattering lengths are calculated to be 2000 and 25 km at frequencies 10 and 30 kHz, respectively; for grain size ˜0.4 cm at 1500 m (the maximum depth to be instrumented acoustically), scattering lengths are calculated to be 250 and 3 km. These are within the range of frequencies where most of the energy of the acoustic wave is concentrated. The absorption length is calculated to be 9 ± 3 km at all frequencies above ˜100 Hz. For NaCl (rock salt) with grain size 0.75 cm, scattering lengths are calculated to be 120 and 1.4 km at 10 and 30 kHz, and absorption lengths are calculated to be 3 × 104 and 3300 km at 10 and 30 kHz. Existing measurements are consistent with theory. For ice, absorption is the limiting factor; for salt, scattering is the limiting factor. Both media would be suitable for detection of acoustic waves from ultrahigh-energy neutrino interactions.

  14. The Hangay Dome, central Mongolia: A relict Mesozoic landscape

    NASA Astrophysics Data System (ADS)

    McDannell, K. T.; Zeitler, P. K.; Ancuta, L. D.; Idleman, B. D.; Boulton, S. L.; Wegmann, K. W.

    2014-12-01

    The Hangay Dome is a broad upland in central Mongolia characterized by a high elevation (>3000-4000 m), low relief landscape within the greater Mongolian Plateau (~2000 m avg. elevation) of central Asia. We have assessed the long-term, large-scale landscape evolution of the region using thermochronologic analysis. Detrital apatite (U-Th-Sm)/He samples from the Selenga River (n = 55) and Orkhon River (n = 15) basins north of the Hangay Dome yield central ages of 134.2 ± 6 and 131.3 ± 9.8 (1σ) Ma, respectively. The regional granitic bedrock apatite (U-Th-Sm)/He single grain age distribution is approximately 95 to 200 Ma, with a homogenized grain central age of 131.2 ± 6.1 Ma. These low-temperature data, in conjunction with K-feldspar MDD 40Ar/39Ar ages of ~200-230 Ma, suggest regional exhumation in the Mesozoic. HeFTy (Ketcham, 2005) modeling corroborates these data and suggests cooling rates of ~3°C/Ma from 220-185 Ma, and applying a geothermal gradient of 21 ± 3°C/km for central Mongolia (Lysak and Dorofeeva, 2003), rock uplift rates from Late Triassic to Mid-Late Jurassic are approximately 100 m/My and from the Early Cretaceous (130 Ma) to the present approximately ≤ 30 m/My. Regional bedrock age patterns, detrital age populations, and thermal modeling suggest that significant recent, rapid rock uplift in central Mongolia is unlikely. Pecube thermo-kinematic models (Braun, 2003) indicate that any rapid (> 500 m/My) event in the Late Miocene-Pliocene would produce Early-Mid Cenozoic cooling ages in lower elevations of the Selenga River drainage basin, which is not supported by the detrital age signal. Pecube modeling of slow rock uplift rates of <50 m/My since the Early Triassic produce regional ages in agreement with geomorphic and geochronologic data. Regional apatite helium age-elevation patterns suggest long-term thermal stability of the upper crust and possible lowering of relief since Mesozoic exhumation. Basalt total fusion 40Ar/39Ar ages

  15. Long-term landscape evolution in the Hangay Dome, Mongolia

    NASA Astrophysics Data System (ADS)

    McDannell, K. T.; Ancuta, L. D.; Smith, S. G.; Idleman, B. D.; Wegmann, K. W.; Zeitler, P. K.

    2013-12-01

    The Hangay Dome in central Mongolia is an example of high-elevation (>3000 m), low-relief topography in a continental interior between the thick Siberian craton to the north and the active Himalaya deformation belt to the far south. Detrital and granitic bedrock apatite (U-Th)/He samples yield ages of ~85-200 Ma and ~95-120 Ma, respectively. These low-temperature data in conjunction with K-feldspar 40Ar/39Ar ages of ~200-225 Ma, raise questions about when this preserved, epeirogenic landscape was uplifted and how it has responded to minimal exhumation since the Mesozoic. Alpine cirques and intact moraine deposits are indicative of a more recent, climate-driven erosional signal in the higher elevation regions of the Hangay. Pecube modeling indicates that a recent, regional uplift signal produces younger, Early-Mid Cenozoic cooling ages in lower elevations of the Selenga River drainage basin to the north of the Hangay Dome. Modeled low exhumation rates of 0.038 mm/yr over 122 Ma generate cooling ages in agreement with preliminary geomorphic and geochronologic results. Basalt total fusion 40Ar/39Ar ages constrain the earliest surface exposure of the landscape to ~30 Ma in the Hangay, with flows as young as ~5 Ka present in a few areas. Geomorphic observations coupled with age-constrained basalt stratigraphy allow us to calculate minimum incision rates in the eastern Hangay for the Miocene and Late Pliocene-Holocene of 0.032 mm/yr and 0.039 mm/yr, respectively. In addition, basalt-bedrock contact mapping in one area places a ~10 Ma old basal flow erupted onto an undulated bedrock surface, suggesting the existence of topography at the time of eruption. Volumetric analysis reveals that rock removed in the past ~6 Ma (uppermost basalt flow age) yields a net erosion rate of 0.037 mm/yr. This rate is also comparable to our 10Be basin-averaged erosion rates from samples collected in adjacent drainages. In contrast to previous inferences that central Mongolia has undergone

  16. New U-Pb SHRIMP dating for the Leo Pargil gneiss dome, western Himalaya

    NASA Astrophysics Data System (ADS)

    Leech, M. L.; Sas, R.

    2006-12-01

    The Leo Pargil gneiss dome is comprised of upper amphibolite-facies metasedimentary rocks of the lower Tethyan Himalayan sequence (the Haimantas unit) that are intruded by numerous small granitoid bodies and leucogranite dikes. The dome is exposed in northern India/southwestern Tibet at the confluence of the Sutlej and Spiti rivers west of the Zada basin. The dome is bound by generally N-S trending normal faults; the western boundary is termed the Kaurik-Chango normal fault and has a history of recent seismicity. The Leo Pargil dome differs from other North Himalayan domes in that it exhibits orogen-parallel stretching lineations and a uniform top-to-the-northwest sense-of-shear on its western flank (in contrast to approximately arc-normal stretching lineations and variable sense-of-shear in other North Himalayan domes; the youngest phase of Leo Pargil dome development is related to an orogen-parallel extensional structure similar to that which bounds the Gurla Mandhata dome to the southeast. New U-Pb SHRIMP dating of zircon yields Late Archean to Late Proterozoic ages for Leo Pargil paragneisses (c. 800-900 Ma and rarer 2-3 Ga zircons) and Late Oligocene to Early Miocene ages for granitoid intrusions (c. 27-16 Ma). These Oligocene to Miocene ages for Leo Pargil granitoids may correspond to magmatism associated with the widespread leucogranite bodies exposed througout the Himalaya. The Leo Pargil dome, like other similar Himalayan gneiss domes, may be exposures of a ductile mid-crustal channel.

  17. Long-term geochemical surveillance of fumaroles at Showa-Shinzan dome, Usu volcano, Japan

    USGS Publications Warehouse

    Symonds, R.B.; Mizutani, Y.; Briggs, P.H.

    1996-01-01

    This study investigates 31 years of fumarole gas and condensate (trace elements) data from Showa-Shinzan, a dacitic dome-cryptodome complex that formed during the 1943-1945 eruption of Usu volcano. Forty-two gas samples were collected from the highest-temperature fumarole, named A-1, from 1954 (800??C) to 1985 (336??C), and from lower-temperature vents. Condensates were collected contemporaneously with the gas samples, and we reanalyzed ten of these samples, mostly from the A-1 vent, for 32 cations and three anions. Modeling using the thermochemical equilibrium program, SOLVGAS, shows that the gas samples are mild disequilibrium mixtures because they: (a) contain unequilibrated sedimentary CH4 and NH3; (b) have unequilibrated meteoric water; or (c) lost CO, either by air oxidation or by absorption by the sodium hydroxide sampling solution. SOLVGAS also enabled us to restore the samples by removing these disequilibrium effects, and to estimate their equilibrium oxygen fugacities and amounts of S2 and CH4. The restored compositions contain > 98% H2O with minor to trace amounts of CO2, H2, HCl, SO2, HF, H2S, CO, S2 and CH4. We used the restored gas and condensate data to test the hypotheses that these time-series compositional data from the dome's fumaroles provide: (1) sufficient major-gas data to analyze long-term degassing trends of the dome's magma-hydrothermal system without the influence of sampling or contamination effects; (2) independent oxygen fugacity-versus-temperature estimates of the Showa-Shinzan dacite; (3) the order of release of trace elements, especially metals, from magma; and (4) useful information for assessing volcanic hazards. The 1954-1985 restored A-1 gas compositions confirm the first hypothesis because they are sufficient to reveal three long-term degassing trends: (1) they became increasingly H2O-rich with time due to the progressive influx of meteoric water into the dome; (2) their C/S and S/Cl ratios decreased dramatically while their Cl

  18. Prospective Type Ia supernova surveys from Dome A

    SciTech Connect

    Kim, A.; Bonissent, A.; Christiansen, J. L.; Ealet, A.; Faccioli, L.; Gladney, L.; Kushner, G.; Linder, E.; Stoughton, C.; Wang, L.

    2010-03-10

    Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over 5 years can yield a spectro-photometric time series of ~;; 1000 z< 0:08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture (>=4-m) telescopes are capable of discovering supernovae shortly after explosion out to z ~;; 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

  19. Prospective Type Ia Supernova Surveys From Dome A

    SciTech Connect

    Kim, A.; Bonissent, A.; Christiansen, J.L.; Ealet, A.; Faccioli, L.; Gladney, L.; Kushner, G.; Linder, E.; Stoughton, C.; Wang, L.; /Texas A-M /Purple Mountain Observ.

    2010-02-01

    Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over five years can yield a spectro-photometric time series of {approx}1000 z < 0.08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture ({approx}>4-m) telescopes are capable of discovering supernovae shortly after explosion out to z {approx} 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

  20. Heavy metals in antarctic ice from Law Dome: initial results.

    PubMed

    Hong, S; Boutron, C F; Edwards, R; Morgan, V I

    1998-08-01

    Pb, Cd, Cu, and Zn have been measured using ultraclean procedures in eight sections taken from two well-dated ice cores from Law Dome, an independent small size ice cap with high accumulation rate situated in the coastal area of East Antarctica. Seven sections were dated from the 1830s to 1940s and one was dated from three millennia ago. The data show that there are strong seasonal variations in the concentrations of Pb and Cd, with values approximately tow-to fourfold higher in winter than in spring-summer. Evaluation of the contributions from the different sources suggests that contribution from sea salt spray is relatively important, especially for Cd. Contribution from marine biogenic emissions could also be very significant. The importance of marine contributions is consistent with strong intrusions of marine air masses at this coastal site, especially during wintertime.

  1. Geometrical nonlinear stability analyses of cable-truss domes.

    PubMed

    Gao, Bo-qing; Lu, Qun-Xin; Dong, Shi-Lin

    2003-01-01

    The nonlinear finite element method is used to analyze the geometrical nonlinear stability of cable-truss domes with different cable distributions. The results indicate that the critical load increases evidently when cables, especially diagonal cables, are distributed in the structure. The critical loads of the structure at different rise-span ratios are also discussed in this paper. It was shown that the effect of the tensional cable is more evident at small rise-span ratio. The buckling of the structure is characterized by a global collapse at small rise-span ratio; that the torsional buckling of the radial truss occurs at big rise-span ratio; and that at proper rise-span ratio, the global collapse and the lateral buckling of the truss occur nearly simultaneously.

  2. A robotic reflective Schmidt telescope for Dome C

    NASA Astrophysics Data System (ADS)

    Strassmeier, K. G.; Andersen, M. I.; Steinbach, M.

    2004-10-01

    This paper lays out a wide-field robotic Schmidt telescope (RST) for the Antarctic site Dome C. The telescope is based on 80/120cm reflective Schmidt optics, built originally for a space project, and a mosaic of four 7.5k×7.5k 8-μm thinned CCDs from the PEPSI/LBT wafer run. The telescope's total field of view (FOV) would be 5o circular (minimum 3o× 3o square) with a plate scale of 0.7 arcsec per pixel. Limiting magnitude is expected to be V=21.5mag in 60 sec for a field of 9 square degrees.

  3. First look at HRCAM images from Dome A, Antarctica

    NASA Astrophysics Data System (ADS)

    Sims, Geoff; Ashley, Michael C. B.; Cui, Xiangqun; Feng, Long Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel M.; Shang, Zhaohui; Storey, John W. V.; Tothill, Nick; Wang, Lifan; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

    2013-01-01

    HRCAM (High Resolution CAMera) is a Canon 50D 15-megapixel digital SLR camera equipped with a Sigma 4.5 mm f/2.8 fish-eye lens. It was installed at Dome A on the Antarctic plateau in January 2010 and photographs the sky every 15 minutes. Primarily functioning as a site-testing instrument, data obtained from HRCAM provide valuable statistics on cloud cover, sky transparency and the distribution and frequency of auroral activity. We present a first look at data from HRCAM during 2010, including an overview of how we intend to reduce the images. We also demonstrate the potential of stellar photometry by using linear combinations of the in-built Canon RGB filters to convert instrumental magnitudes into the photometric BVR bands.

  4. Sojourner Rover View of Shark and Half Dome

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The rounded knobs (arrows) up to 3 or 4 cm wide on Shark (left; approximately 70 cm wide)) and Half Dome (upper right) and in the foreground could be pebbles in a cemented matrix of clays, silts, and sands; such rocks are called conglomerates. Well-rounded objects like these were not seen at the Viking sites.

    NOTE: original caption as published in Science Magazine.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  5. IRAIT: a Facility for IR Astronomy at Dome C

    NASA Astrophysics Data System (ADS)

    Tosti, Gino; Busso, Maurizio

    We present the status of IRAIT (Italian Robotic Antarctic Infrared Telescope) and the plans for its forthcoming installation at the Antarctic base of Dome C. After a short description of the telescope itself and of the auxiliary equipment for its transportation and quick setup in Antarctica we review the foreseen focal plane instrumentation including a near infrared image-spectrometer and a mid infrared camera. Recent developments of the collaboration in Europe aimed at upgrading the project to a really international effort are described and the role of French and Spanish teams in the new scheme are outlined. Finally some key projects that should especially benefit from a permanent in infrared facility in Antarctica are illustrated in the fields of stellar and extragalactic physics.

  6. Behaviour of Atmospheric Boundary Layer Height at Dome C, Antarctica

    NASA Astrophysics Data System (ADS)

    Pietroni, I.; Argentini, S.

    2009-09-01

    The Antarctic Atmospheric Boundary Layer presents characteristics which are substantially different from the mid-latitudes ABLs. On the Antarctic plateau two different extreme situations are observed. During the summer a mixing height develops during the warmer hours of the day although the sensible heat flux is reduced compared to that at mid-latitudes. During the winter a long lived stable boundary layer is continuously present, the residual layer is never observed, consequently the inversion layer is connected at the free atmosphere. To understand the stable ABL process the STABLEDC (Study of the STAble Boundary Layer Environmental at Dome C) experimental field was held at Concordia, the French Italian plateau station at Dome C, during 2005. In the same period the RMO (Routine Measurements Observations) started. The data included turbulence data at the surface, temperature profiles by a microwave profiler (MTP-5P), a mini-sodar and radio-soundings. In this work we will show the results of a comparison of the ABL height at Concordia (3233 m a.s.l) during the summer and the winter using direct measurements and parameterization. The winter ABL height was estimated directly using experimental data (radio-soundings and radiometer temperature and wind velocity profiles) and different methods proposed in literature. The stable ABL height was also estimated using the formulation proposed by Zilitinkevich et al. (2007) for the long-lived stable boundary layer. The correlation of ABL height with the temperature and wind speed is also shown. The summer mixing height was instead estimated by mini-sodar data and compared with the height given by the model suggested by Batchvarova and Gryning (1991) which use as input the turbulence data.

  7. Cambrian to Holocene structural and burial history of Nashville dome

    SciTech Connect

    Stearns, R.G.; Reesman, A.L.

    1986-02-01

    About 14,000 ft (4270 m) of strata covered basement over the present crest of the Nashville dome by the end of the Paleozoic (calculated by estimating the geothermal gradient, and using temperatures of veins in Stones River Group and Knox Dolomite). At least 7500 ft (2290 m) of post-Devonian strata have been removed by subsequent erosion. Estimates of other erosional episodes include 350 ft (107 m) of upper Knox (during the Middle Ordovician) and 500 ft (152 m) of Devonian-Ordovician (during the Late Devonian). Mesozoic to Holocene uplift was at least 6350 ft (1940 m), 1500 ft or 460 m (25%) of which occurred in the latest 100 m.y. and 450 ft or 140 m (7%) during the latest 2 m.y., a rate ranging from about 15 ft/m.y. (4.6 m/m.y.) for the longer term to over 225 ft/m.y. (70 m/m.y.) in the Pleistocene to Holocene. Earliest structure of the area was a series of elongate basins, probably rifts synchronous with Reelfoot rift to the west. Uplifts trending N10/sup 0/E moved about 40 mi (65 km) westward during the Middle Ordovician. These may relate to similar trending (and moving) Appalachian orogenic events. A change to uplifts trending N50/sup 0/E (parallel to strikes of Appalachian thrusts) occurred in the Late Ordovician and continued to the Devonian; this may reflect a similar Late Ordovician change in the orientation of Appalachian tectonism. In the interval from post-Mississippian to Late Cretaceous, the dome curved westward to join the Pascola arch in response to Ouachita activity. 11 figures, 3 tables.

  8. Designing the SALT facility to minimize dome seeing effects

    NASA Astrophysics Data System (ADS)

    de Kock, Mariana; Venter, Sarel J.

    2003-02-01

    Aspects of the design and experience of the Hobby-Eberly Telescope (HET) were incorporated in the SALT facility design. The characteristics of the local environment were taken into account to ensure a building that is cost effective and functional. The effect of heat from the control room and other warm areas were studied and their locations changed to limit thermal effects. A steel false floor, incorporating forced ventilation and extending around the telescope azimuth pier, was installed. This prevents heat radiating from large concrete surfaces with temperatures potentially higher than ambient. Because site testing (i.e. micro thermal measurements) indicated high turbulence within ~5 m of the ground level, the telescope and pier were raised to improve dome seeing. The SALT site is significantly windy all year round (median velocity = 4.8 m/s), and this was utilized to design better ventilation of the facility using adjustable louvers for natural ventilation. Results of a computational fluid dynamic analysis (CFD) are presented which show an adequate temperature distribution at wind speeds as low as 0.5 m/s. The telescope chamber and dome are build out of insulation panels to ensure low thermal losses during the day when the chamber is air conditioned and thus limit electricity consumption and thermal gradients. Large equipment that emit heat or vibration are housed in a separate utility building 50 m from the telescope in the non-prevailing wind direction in order to limit their effect on the telescope. Vented air from the building is also released at this site.

  9. Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr

    NASA Astrophysics Data System (ADS)

    Fujita, S.; Parrenin, F.; Severi, M.; Motoyama, H.; Wolff, E. W.

    2015-10-01

    Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were volcanically synchronized to improve our understanding of their chronologies. Within the past 216 kyr, 1401 volcanic tie points have been identified. DFO2006 is the chronology for the DF core that strictly follows O2 / N2 age constraints with interpolation using an ice flow model. AICC2012 is the chronology for five cores, including the EDC core, and is characterized by glaciological approaches combining ice flow modelling with various age markers. A precise comparison between the two chronologies was performed. The age differences between them are within 2 kyr, except at Marine Isotope Stage (MIS) 5. DFO2006 gives ages older than AICC2012, with peak values of 4.5 and 3.1 kyr at MIS 5d and MIS 5b, respectively. Accordingly, the ratios of duration (AICC2012 / DFO2006) range between 1.4 at MIS 5e and 0.7 at MIS 5a. When making a comparison with accurately dated speleothem records, the age of DFO2006 agrees well at MIS 5d, while the age of AICC2012 agrees well at MIS 5b, supporting their accuracy at these stages. In addition, we found that glaciological approaches tend to give chronologies with younger ages and with longer durations than age markers suggest at MIS 5d-6. Therefore, we hypothesize that the causes of the DFO2006-AICC2012 age differences at MIS 5 are (i) overestimation in surface mass balance at around MIS 5d-6 in the glaciological approach and (ii) an error in one of the O2 / N2 age constraints by ~ 3 kyr at MIS 5b. Overall, we improved our knowledge of the timing and duration of climatic stages at MIS 5. This new understanding will be incorporated into the production of the next common age scale. Additionally, we found that the deuterium signals of ice, δDice, at DF tends to lead the one at EDC, with the DF lead being more pronounced during cold periods. The lead of DF is by +710 years (maximum) at MIS 5d, -230 years (minimum) at MIS 7a and +60

  10. UltraForm finishing

    NASA Astrophysics Data System (ADS)

    Fess, E.; Schoen, J.; Bechtold, M.; Mohring, D.

    2005-05-01

    A new compliant sub-aperture optical finishing technique is being investigated for the removal of mid-spatial frequency artifacts and smoothing of hard polycrystalline infrared ceramics for aspheric applications and conformal shaped optics. The UltraForm concept was developed by OptiPro Systems, Ontario, NY, and is a joint process development effort with the Center for Optics manufacturing (COM). The UltraForm tool is a pressurized, elastomeric bladder in the shape of a toroid. Finishing pads are attached to the periphery, allowing the use of a wide variety of pad materials and abrasive selections. Experimentation has been conducted using both slurry mixes and fixed abrasive pads. The toroidal tool is rotated while the compliant tool is compressed into contact with the surface. Currently this process has specific interest for the finishing of conformal ALON Domes. Also to be discussed will be new versions of the UltraForm Tools which are currently be developed and tested.

  11. Insights into the Timing, Origin, and Deformation of the Highland Mountains Gneiss Dome in Southwestern Montana, USA

    NASA Astrophysics Data System (ADS)

    Boyer, Lane Markes

    The Highland Mountains of southwestern Montana offer a unique view of the Archean igneous and metamorphic rocks within the Great Falls tectonic zone (GFTZ). A Paleoproterozoic structural gneiss dome has been interpreted in the southern extent of the Highland Mountains. The ˜ 130km2 of exhumed metamorphic rocks and gneiss dome exposed in the Highland Mountains are the primary focus of this research. The formation of the Highland Mountains gneiss dome is proposed to be directly related to a northwest-side down detachment (the Steels Pass shear zone) that formed during terrane collision along the GFTZ. The field investigation determined foliation and lineation orientation measurements taken at 65 stations. Twenty-two field oriented samples were obtained from a variety of rock types distributed across the ˜ 24 km2 field area. Three field-based domains were established from the lithology, foliation, and lineation observations. Full-section X-ray maps of three sample thin-sections were collected via EPMA to identify all monazite grains. Twenty-eight grains were mapped at high-spatial resolution (0.3--6.0 mum). Thin section micro-structures observed show effects of a multistage deformation history with both dynamic and static recrystallization processes. Monazite geochronology of one thin section revealed two distinct populations of monazite grains; Archean (˜ 2.5 Ga) and Mesoproterozoic (˜ 1.5 Ga). The older population represents the crystallization age of either, or both the Medicine Hat block and the Wyoming province terranes. The younger population is hypothesized to have grown during deformation/alteration associated with the formation of the Belt-Purcell Rift Basin.

  12. Bayesian Inversion using Physics-based Models Applied to Dome Extrusion at Mount St. Helens 2004-2008

    NASA Astrophysics Data System (ADS)

    Wong, Y. Q.; Segall, P.; Anderson, K. R.; Bradley, A. M.

    2015-12-01

    Physics-based models of volcanic eruptions have grown more sophisticated over the past few decades. These models, combined with Bayesian inversion, offer the potential of integrating diverse geological and geophysical datasets to better understand volcanic systems. Using a Markov Chain Monte Carlo (MCMC) algorithm with a physics-based conduit model, we invert data from the 2004-2008 dome-forming eruption at Mount St. Helens, USA. We extend the 1D cylindrical conduit model of Anderson and Segall [2011] to include vertical and lateral gas loss from the magma, as well as equilibrium crystallization. The melt viscosity increases strongly with crystal content. Magma permeability obeys the Kozeny-Carman law with a threshold porosity. Excess pressure in the magma chamber drives Newtonian flow of magma upwards until the viscous resistance to flow exceeds the rate-dependent frictional strength on the conduit wall, at which point the magma transitions from viscous flow to plug flow. We investigate the steady-state solutions for lava dome growth between March and December 2005, in which magma chamber pressure, initial water content, permeability and friction parameters are unknown model parameters. These parameters are constrained by: dome rock porosity, extrusion rate from photogrammetry, plug depth from drumbeat earthquakes, and crystallization pressure from petrologic studies. Posterior probability density functions (PDFs) reveal the constraints on the model parameters and their correlations. Assuming lithostatic normal stress on the plug, low coefficients of friction (0.1-0.3) are required to allow extrusion at the observed rate while maintaining reasonable magma chamber pressures. Lower effective normal stress or melt viscosity could allow for larger friction coefficients. Future work will investigate the time-dependent system, thereby allowing us to incorporate time-evolving geodetic and eruption rate data into the inversion.

  13. Degassing history of a mid-ocean ridge rhyolite dome on the Alarcon Rise, Gulf of California

    NASA Astrophysics Data System (ADS)

    Portner, R. A.; Dreyer, B. M.; Clague, D. A.; Lowenstern, J. B.; Head, J. W., III; Saal, A. E.

    2014-12-01

    A 2350 meter deep rhyolite lava dome and surrounding intermediate-mafic complex on the Alarcon Rise mid-ocean ridge in the Gulf of California was sampled extensively during a 2012 MBARI expedition. The dome is predominantly composed of sparsely vesicular (<10%) obsidian with local deposits of pumiceous breccia. Pumiceous lapilli comprise highly vesicular (40-60%) fracture networks that separate non-vesicular obsidian "pseudoclasts". Textures and major element geochemistry suggest that both lithologies originated from the same magma that formed the majority of the dome. This is corroborated by comparable major element compositions (~75% SiO2) and near-equilibrium phenocryst assemblages including olivine (Fo10) and plagioclase (An17). Attenuated total reflectance (ATR) and transmission FTIR spectroscopy was used to measure H2O concentrations in olivine and plagioclase melt inclusions as well as host glasses (CO2 was below detection, <30 ppm). Rhyolite host glass contains 1.5-2.0 wt% H2O, similar to nearby andesite and dacite. These concentrations agree with saturation limits for H2O (1.7%) at the depth of Alarcon Rise, but are slightly less than what is predicted by fractional crystallization modeling. Melt inclusions from plagioclase and olivine in rhyolite contain a maximum of 3.5-4.5% H2O suggesting that up to 3.0% H2O exsolved into bubbles during a 3 km ascent. Hydrostatic pressures (23 MPa) at the eruptive vent would have permitted 53% vesiculation in agreement with petrographic observations. Although ~50% vesiculation and exsolved H2O contents of 3.0 wt% are less than the ideal threshold for magmatic fragmentation, the presence of highly vesicular ash particles representing fragmented pumiceous breccia argues otherwise. We posit that decoupled volatiles from a deeper magma body migrated through fracture networks to the surface causing mild explosivity.

  14. Real-Time Measurements of Aft Dome Insulation Erosion on Space Shuttle Reusable Solid Rocket Motor

    NASA Technical Reports Server (NTRS)

    McWhorter, Bruce; Ewing, Mark; Albrechtsen, Kevin; Noble, Todd; Longaker, Matt

    2004-01-01

    Real-time erosion of aft dome internal insulation was measured with internal instrumentation on a static test of a lengthened version of the Space Shuffle Reusable Solid Rocket Motor (RSRM). This effort marks the first time that real-time aft dome insulation erosion (Le., erosion due to the combined effects of thermochemical ablation and mechanical abrasion) was measured in this kind of large motor static test [designated as Engineering Test Motor number 3 (ETM3)I. This paper presents data plots of the erosion depth versus time. The data indicates general erosion versus time behavior that is in contrast to what would be expected from earlier analyses. Engineers have long known that the thermal environment in the aft dome is severe and that the resulting aft dome insulation erosion is significant. Models of aft dome erosion involve a two-step process of computational fluid dynamics (CFD) modeling and material ablation modeling. This modeling effort is complex. The time- dependent effects are difficult to verify with only prefire and postfire insulation measurements. Nozzle vectoring, slag accumulation, and changing boundary conditions will affect the time dependence of aft dome erosion. Further study of this data and continued measurements on future motors will increase our understanding of the aft dome flow and erosion environment.

  15. The annual cycle and biological effects of the Costa Rica Dome

    NASA Astrophysics Data System (ADS)

    Fiedler, Paul C.

    2002-02-01

    The Costa Rica Dome is similar to other tropical thermocline domes in several respects: it is part of an east-west thermocline ridge associated with the equatorial circulation, surface currents flow cyclonically around it, and its seasonal evolution is affected by large-scale wind patterns. The Costa Rica Dome is unique because it is also forced by a coastal wind jet. Monthly climatological fields of thermocline depth and physical forcing variables (wind stress curl and surface current divergence) were analyzed to examine the structure and seasonal evolution of the dome. The annual cycle of the dome can be explained by wind forcing in four stages: (1) coastal shoaling of the thermocline off the Gulf of Papagayo during February-April, forced by Ekman pumping on the equatorward side of the Papagayo wind jet; (2) separation from the coast during May-June when the intertropical convergence zone (ITCZ) moves north to the countercurrent thermocline ridge, the wind jet stops, and the North Equatorial Countercurrent extends toward the coast on the equatorward flank of the ridge; (3) countercurrent thermocline ridging during July-November, when the dome expands to the west as the countercurrent thermocline ridge shoals beneath a band of cyclonic wind stress curl on the poleward side of the ITCZ; and (4) deepening during December-January when the ITCZ moves south and strong trade winds blow over the dome. Coastal eddies may be involved in the coastal shoaling observed during February-March. A seasonally predictable, strong, and shallow thermocline makes the Costa Rica Dome a distinct biological habitat where phytoplankton and zooplankton biomass are higher than in surrounding tropical waters. The physical structure and biological productivity of the dome affect the distribution and feeding of whales and dolphins, probably through forage availability.

  16. Analysis of thermal shock resistance of CVD ZnS dome

    NASA Astrophysics Data System (ADS)

    Zhang, Daijun; Luo, Haibo; Zhou, Peipei; Hou, Xinglin

    2016-10-01

    Since the dome experiences the convective heat loading, thermal stress will be generated in the thickness direction. Thus, estimation of the thermal shock and analysis of the thermal shock resistance of the dome are the key to the design of the dome. In this paper, thermal shock resistance of CVD ZnS dome is analysed based on the flight condition of 6000m altitude and 3.0 Mach. We obtained the critical Reynolds number through a rockets pry experiment, which deduced that there exists a transition from laminar flow to turbulent flow at somewhere over the dome. We calculated the heat transfer coefficient over dome through heat transfer coefficient engineering formula of high-speed sphere with turbulent boundary layer near the stagnation point. The largest heat transfer coefficient is 2590W/(m2.K). Then, we calculated the transient thermal stress of dome by using the finite element method. Then we obtained the temperature and thermal stress distribution of different time through the direction of thickness. In order to obtain the mechanical properties of CVD ZnS at high temperatures, the 3-point bending method was used to test the flexure strength of CVD ZnS at different temperature. When compared the maximum thermal stress with flexure strength at different temperature, we find that the safety factors were not less than 1.75. The result implied that the dome has good safety margin under the proposed application condition. Through the above test and analysis, we can get the conclusion that the thermal shock resistance of the CVD ZnS dome satisfied the requirements of flight conditions.

  17. Analysis of the imaging performance of panoramic annular lens with conic conformal dome

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Bai, Jian

    2015-10-01

    Panoramic annular lens (PAL) is a kind of the specific wide angle lenses which is widely applied in panoramic imaging especially in aerospace field. As we known, to improve the aerodynamic performance of the aircraft, conformal dome, which notably reduces the drag of an aircraft, is also functioning as an optical window for the inbuilt optical system. However, there is still no report of the specific analysis of the imaging performance of PAL with conformal dome, which is imperative in its aerospace-related applications. In this paper, we propose an analysis of the imaging performance of a certain PAL with various conic conformal domes. Working in visible wavelength, the PAL in our work observes 360° surroundings with a large field of view (FOV) ranging from 30° ~105° . Meanwhile, various thicknesses, half-vertex angles, materials of the conic dome and the central distances between the dome and PAL are considered. The imaging performances, mainly indicated by modulation transfer function (MTF) as well as RMS radius of the spot diagram, are systematically compared. It is proved that, on the contrary to the general cases, the dome partly contributes to the imaging performance of the inbuilt PAL. In particular, with a conic conformal dome in material of K9 glass with a half-vertex angle of 25° and a thickness of 6mm, the maximum MTF at 100lp/mm could be improved by 6.68% with nearly no degeneration of the minimum MTF, and the RMS radius could be improved by 14.76% to 19.46% in different FOV. It is worth to note that the PAL is adaptive to panoramic aerospace applications with conic or quasi-conic conformal dome and the co-design of both PAL and the dome is very important.

  18. Sampling of Breathable Air in U.S. Navy Sonar Domes

    DTIC Science & Technology

    1994-03-01

    USS Kidd 4/92 154 ( DDG - 993 ) USS Donald B. Beary (FF- 6/92 41 1085) USS Truett 6/92 149 (FF-1095) USS San Jacinto 6/92 70 (CG-56) USS Hue City 9/92 32...pressure-tight bulkhead in the center of the dome. On the DD-963, and DDG - 993 , and CG-47 class ships (i.e., destroyers and 5 cruisers), samples of dome air...Command. NAVSEA S9165-AH-MMA-010. Technical manual for sonar dome rubber window SDRW-1 for DD-963, DDG - 993 , and CG-47 class vessels. Revision 1,

  19. Design and Test of Low-Profile Composite Aerospace Tank Dome

    NASA Technical Reports Server (NTRS)

    Ahmed, R.

    1999-01-01

    This report summarizes the design, analysis, manufacture, and test of a subscale, low-profile composite aerospace dome under internal pressure. A low-profile dome has a radius-to-height ratio greater than the square root of two. This effort demonstrated that a low-profile composite dome with a radius-to-height ratio of three was a feasible design and could adequately withstand the varying stress states resulting from internal pressurization. Test data for strain and displacement versus pressure are provided to validate the design.

  20. Non-Newtonian Convection and Compositional Buoyancy: Advances in Modeling Convection and Dome Formation on Europa

    NASA Technical Reports Server (NTRS)

    Pappalardo, R. T.; Barr, A. C.

    2004-01-01

    Numerical modeling of non-Newtonian convection in ice shows that convection controlled by grain boundary sliding rheology may occur in Europa. This modeling confirms that thermal convection alone cannot produce significant dome elevations. Domes may instead be produced by diapirs initiated by thermal convection that in turn induces compositional segregation. Exclusion of impurities from warm upwellings would allow sufficient buoyancy for icy plumes to account for the observed approximately 100 m topography of domes, provided the ice shell has a small effective elastic thickness (approximately 0.2 to 0.5 km) and contains low eutectic-point impurities at the few percent level.

  1. Origin of Domes on Europa: The Role of Thermally Induced Compositional Buoyancy,

    NASA Technical Reports Server (NTRS)

    Pappalardo, R. T.; Barr, A. C.

    2004-01-01

    The surface of Jupiter's moon Europa is peppered by topographic domes, interpreted as sites of intrusion and extrusion. Diapirism is consistent with dome morphology, but thermal buoyancy alone cannot produce sufficient driving pressures to create the observed dome elevations. Instead, diapirs may initiate by thermal convection that induces compositional segregation. Exclusion of impurities from warm upwellings allows sufficient buoyancy for icy plumes to create the observed surface topography, provided the ice shell has a small effective elastic thickness (0.2 to 0.5 km) and contains low-eutectic point impurities at the few percent level. This model suggests that the ice shell may be depleted in impurities over time.

  2. Electro-Spun Poly(vinylidene fluoride) Nanofiber Web as Separator for Lithium Ion Batteries: Effect of Pore Structure and Thickness.

    PubMed

    Lim, Seung-Gyu; Jo, Hye-Dam; Kim, Chan; Kim, Hee-Tak; Chang, Duck-Rye

    2016-01-01

    Electro-spun nanofiber web is highly attractive as a separator for lithium ion batteries because of its high electrical properties. In moving toward wider battery applications of the nanofiber separators, a deeper understanding on the structure and property relationship is highly meaningful. In this regard, we prepared electro-spun poly(vinylidene fluoride) (PVdF) webs with various thicknesses (10.5~100 µm) and investigated their structures and electrochemical performances. As the thickness of the web is decreased, a decrease of porosity and an increase of pore size are resulted in. For the 10.5 µm-thick separator, a minor short-circuit was detected, stressing the importance of reducing pore-size on prevention of short-circuit. However, above the thickness of 21 µm, well-connected, submicron-sized pores are generated, and, with lowering the separator thickness, discharge capacity and rate capability are enhanced owing to the lowered area-specific resistance.

  3. Evolution of the microstructure and hardness of a rapidly solidified/melt-spun AZ91 alloy upon aging at different temperatures

    SciTech Connect

    Wang Baishu; Liu Yongbing; An Jian; Li Rongguang; Su Zhenguo; Su Guihua; Lu You; Cao Zhanyi

    2009-04-15

    The effect of aging at different temperatures on a rapidly solidified/melt-spun AZ91 alloy has been investigated in depth. The microstructures of as-spun and aged ribbons with a thickness of approximately 60 {mu}m were characterized using X-ray diffraction, transmission electron microscopy and laser optical microscopy; microhardness measurements were also conducted. It was found that the commercial AZ91 alloy undergoes a cellular/dendritic transition during melt-spinning at a speed of 34 m/s. A strengthening effect due to aging was observed: a maximum hardness of 110 HV/0.05 and an age-hardenability of 50% were obtained when the ribbon was aged at 200 deg. C for 20 min. The {beta}-Mg{sub 17}Al{sub 12} phase exhibits net and dispersion types of distribution during precipitation. The dispersion of precipitates in dendritic grains or cells is the main source of strengthening.

  4. An Analysis of Gas Pressure Forming of Superplastic AL 5083 Alloy

    SciTech Connect

    Syn, C K; O'Brien, M J; Lesuer, D R; Sherby, O D

    2001-05-04

    Al 5083 disks of a superplastic forming grade were gas-pressure formed to hemispheres and cones at constant forming pressures with and without back pressure. The forming operation was performed using an in-house designed and built biaxial forming apparatus. The temporal change of dome heights of the hemispheres and cones were measured for the different forming and back pressures applied. The flow stresses and strain rates developed at the top of the dome during the forming step were shown to closely follow the flow stress-strain rate relationship obtained from the strain rate change tests performed at the same temperature using uniaxial tensile samples.

  5. Precipitation regime and stable isotopes at Dome Fuji, East Antarctica

    NASA Astrophysics Data System (ADS)

    Dittmann, Anna; Schlosser, Elisabeth; Masson-Delmotte, Valérie; Powers, Jordan G.; Manning, Kevin W.; Werner, Martin; Fujita, Koji

    2016-06-01

    A unique set of 1-year precipitation and stable water isotope measurements from the Japanese Antarctic station, Dome Fuji, has been used to study the impact of the synoptic situation and the precipitation origin on the isotopic composition of precipitation on the Antarctic Plateau. The Antarctic Mesoscale Prediction System (AMPS) archive data are used to analyse the synoptic situations that cause precipitation. These situations are investigated and divided into five categories. The most common weather situation during a precipitation event is an upper-level ridge that extends onto the Antarctic Plateau and causes strong northerly advection from the ocean. Most precipitation events are associated with an increase in temperature and wind speed, and a local maximum of δ18O. During the measurement period, 21 synoptically caused precipitation events caused 60 % of the total annual precipitation, whereas the remaining 40 % were predominantly attributed to diamond dust. By combining the synoptic analyses with 5-day back-trajectories, the moisture source regions for precipitation events were estimated. An average source region around a latitude of 55° S was found. The atmospheric conditions in the source region were used as initial conditions for running a Rayleigh-type isotopic model in order to reproduce the measured isotopic composition of fresh snow and to investigate the influence of the precipitation source region on the isotope ratios. The model represents the measured annual cycle of δ18O and the second-order isotopic parameter deuterium excess reasonably well, but yields on average too little fractionation along the transport/cooling path. While simulations with an isotopic general circulation model (GCM) (ECHAM5-wiso) for Dome Fuji are on average closer to the observations, this model cannot reproduce the annual cycle of deuterium excess. In the event-based analysis, no evidence of a correlation of the measured deuterium excess with the latitude of the

  6. Water-quality data for aquifers, streams, and lakes in the vicinity of Keechi, Mount Sylvan, Oakwood, and Palestine salt domes, northeast Texas salt-dome basin

    USGS Publications Warehouse

    Carr, Jerry E.; Halasz, Stephen J.; Liscum, Fred

    1980-01-01

    This report contains water-quality data for aquifers, streams, and lakes in the vicinity of Keechi, Mount Sylvan, Oakwood, and Palestine Salt Domes, in the northeast Texas salt-dome basin. Water-quality data were compiled for aquifers in the Wilcox Group, the Carrizo Sand, and the Queen City Sand. The data include analyses for dissolved solids, pH, temperature, hardness, calcium, magnesium, sodium, bicarbonate, chloride, and sulfate. Water-quality and streamflow data were obtained from 63 surface-water sites in the vicinity of the domes. These data include water discharge, specific conductance, pH, water temperature, and dissolved oxygen. Samples were collected at selected sites for analysis of principal and selected minor dissolved constituents.

  7. Discovery of Critical Oxygen Content for Glass Formation in Zr80Pt20 Melt Spun Ribbons

    SciTech Connect

    D.J. Sordelet; E.A. Rozhkova; X. Yang; M.J. Kramer

    2004-09-30

    Zr{sub 80}Pt{sub 20} alloys may form meta-stable quasicrystals either during devitrification of an amorphous phase or directly upon cooling from a liquid depending on processing conditions. To date, little attention has been given to the role of oxygen on the glass formation or devitrification behavior of Zr-Pt and similar alloys. This study reveals that oxygen content during melt spinning indeed strongly influences the formation of the as-quenched structure. A critical amount of oxygen was found to be required to form amorphous ribbons at a fixed quench rate. At lower oxygen levels (i.e., <500 ppm mass), a fully crystallized is formed; the structure is composed mainly of meta-stable {beta}-Zr with a small fraction of a quasicrystalline phase. At higher oxygen levels, the as-quenched structure transitions to a fully amorphous structure ({approx}1000 ppm mass), and with further oxygen addition forms a mixture of amorphous and quasicrystalline ({approx}1500 ppm mass) or crystalline phases (>2500 ppm mass). Details regarding the structure of the meta-stable {beta}-Zr phase in the low-oxygen ribbons are provided along with a discussion of the structural similarity between this phase and the quasicrystal structure that formed in this alloy.

  8. Salt-dome locations in the Gulf Coastal Plain, South-Central United States

    USGS Publications Warehouse

    Beckman, J.D.; Williamson, A.K.

    1990-01-01

    Information on salt domes in Gulf of Mexico Coastal Plain, south-central United States and the adjacent Continental Shelf were compiled from major published sources, 1973-84. The location of 624 salt domes is shown on a map at a scale of 1:1 ,500,000. A color-coding system was used to show that the occurrence, size, shape, and location of these domes varies among sources. Two tables of additional data accompany the map and include other available information such as: identifying sources, depth to salt and caprock, diameter, volume, name, and uppermost zone of surrounding sediment that is penetrated, as well as the number of matches between sources. The locations of salt domes that penetrate specific zones within the gulf coast regional aquifer system are shown on maps. (USGS)

  9. Observation of Double-Dome Superconductivity in Potassium-Doped FeSe Thin Films.

    PubMed

    Song, Can-Li; Zhang, Hui-Min; Zhong, Yong; Hu, Xiao-Peng; Ji, Shuai-Hua; Wang, Lili; He, Ke; Ma, Xu-Cun; Xue, Qi-Kun

    2016-04-15

    We report on the emergence of two disconnected superconducting domes in alkali-metal potassium- (K-)doped FeSe ultrathin films grown on graphitized SiC(0001). The superconductivity exhibits hypersensitivity to K dosage in the lower-T_{c} dome, whereas in the heavily electron-doped higher-T_{c} dome it becomes spatially homogeneous and robust against disorder, supportive of a conventional Cooper-pairing mechanism. Furthermore, the heavily K-doped multilayer FeSe films all reveal a large superconducting gap of ∼14  meV, irrespective of film thickness, verifying the higher-T_{c} superconductivity only in the topmost FeSe layer. The unusual finding of a double-dome superconducting phase is a step towards the mechanistic understanding of superconductivity in FeSe-derived superconductors.

  10. Glacial/interglacial variations in methanesulfonate (MSA) in the Siple Dome ice core, West Antarctica

    NASA Astrophysics Data System (ADS)

    Saltzman, Eric S.; Dioumaeva, Irina; Finley, Brandon D.

    2006-06-01

    Methanesulfonate (MSA) in the Siple Dome ice core is a record of the deposition of biogenic sulfur to the West Antarctic ice sheet covering the past 100 kyr. Siple Dome MSA levels were low during the last glacial maximum, and increased to higher Holocene levels with a several kyr lag relative to the deglacial warming. The positive correlation between MSA and temperature at Siple Dome is similar to that in Greenland ice cores (Renland, GISP2, and GRIP), and stands in contrast to the negative correlation observed at Vostok, East Antarctica. The Siple Dome MSA data suggest that the sign of the high latitude dust/sulfur/climate feedback is negative, at least for the Pacific sector of the high latitude Southern ocean. These results challenge the idea that fertilization by increased dust deposition led to widespread increased DMS emissions from this region of the glacial Southern Ocean.

  11. Heat flow in salt-dome basins of Eurasia: A comparative study

    NASA Astrophysics Data System (ADS)

    Khutorskoi, M. D.; Teveleva, E. A.; Tsybulya, L. A.; Urban, G. I.

    2010-07-01

    The geothermal fields in the Pericaspian, Pripyat, and North German basins are considered. These basins are characterized by widespread Upper Paleozoic evaporite sequences, which underwent halokinesis with the formation of salt domes and plugs owing to tectonic and gravity instability. Heat flow refraction occurs at the boundaries of the domes with country rocks due to the contrast in thermal conductivity of evaporites and terrigenous rocks between the domal zones. This is the main cause of heat flow variation in the lateral and vertical directions in the salt-dome basins. Close correlation between zones of elevated temperature in the sedimentary rocks and petroleum occurrences is confirmed by the results of 2D and 3D modeling of the geothermal field. The previously noted relations of oil and gas fields to the deep faults in the studied basins create prerequisites for consideration of the geothermal field as a genetic factor controlling the tectonic features and petroleum resources of the salt-dome basins.

  12. Instant snapshot of the internal structure of Unzen lava dome, Japan with airborne muography

    PubMed Central

    Tanaka, Hiroyuki K. M.

    2016-01-01

    An emerging elementary particle imaging technique called muography has increasingly been used to resolve the internal structures of volcanoes with a spatial resolution of less than 100 m. However, land-based muography requires several days at least to acquire satisfactory image contrast and thus, it has not been a practical tool to diagnose the erupting volcano in a real time manner. To address this issue, airborne muography was implemented for the first time, targeting Heisei-Shinzan lava dome of Unzen volcano, Japan. Obtained in 2.5 hours, the resultant image clearly showed the density contrast inside the dome, which is essential information to predict the magnitude of the dome collapse. Since airborne muography is not restricted by topographic conditions for apparatus placements, we anticipate that the technique is applicable to creating images of this type of lava dome evolution from various angles in real time. PMID:28008978

  13. Instant snapshot of the internal structure of Unzen lava dome, Japan with airborne muography

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroyuki K. M.

    2016-12-01

    An emerging elementary particle imaging technique called muography has increasingly been used to resolve the internal structures of volcanoes with a spatial resolution of less than 100 m. However, land-based muography requires several days at least to acquire satisfactory image contrast and thus, it has not been a practical tool to diagnose the erupting volcano in a real time manner. To address this issue, airborne muography was implemented for the first time, targeting Heisei-Shinzan lava dome of Unzen volcano, Japan. Obtained in 2.5 hours, the resultant image clearly showed the density contrast inside the dome, which is essential information to predict the magnitude of the dome collapse. Since airborne muography is not restricted by topographic conditions for apparatus placements, we anticipate that the technique is applicable to creating images of this type of lava dome evolution from various angles in real time.

  14. Rheology of Lava Flows on Europa and the Emergence of Cryovolcanic Domes

    NASA Technical Reports Server (NTRS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Steve M.

    2015-01-01

    There is ample evidence that Europa is currently geologically active. Crater counts suggest that the surface is no more than 90 Myr old, and cryovolcanism may have played a role in resurfacing the satellite in recent geological times. Europa's surface exhibits many putative cryovolcanic features, and previous investigations have suggested that a number of domes imaged by the Galileo spacecraft may be volcanic in origin. Consequently, several Europa domes have been modeled as viscous effusions of cryolava. However, previous models for the formation of silicic domes on the terrestrial planets contain fundamental shortcomings. Many of these shortcomings have been alleviated in our new modeling approach, which warrants a re-assessment of the possibility of cryovolcanic domes on Europa.

  15. Hydrogen-isotope evidence for extrusion mechanisms of the Mount St Helens lava dome

    NASA Technical Reports Server (NTRS)

    Anderson, Steven W.; Fink, Jonathan H.

    1989-01-01

    Hydrogen isotope analyses were used to determine water content and deuterium content for 18 samples of the Mount St Helens dome dacite in an attempt to identify the triggering mechanisms for periodic dome-building eruptions of lava. These isotope data, the first ever collected from an active lava dome, suggest a steady-state process of magma evolution combining crystallization-induced volatile production in the chamber with three different degassing mechanisms: closed-system volatile loss in the magma chamber, open-system volatile release during ascent, and kinetically controlled degassing upon eruption at the surface. The data suggest the future dome-building eruptions may require a new influx of volatile-rich magma into the chamber.

  16. Regional tectonic context, timing, and intrusion mechanism of gneiss domes, eastern Papua New Guinea, from offshore seismic reflection and well data

    NASA Astrophysics Data System (ADS)

    Fitz, G. G.; Mann, P.; Lavier, L. L.

    2011-12-01

    The D'Entrecasteaux Island (DEI) gneiss domes are fault-bounded topographic domes with ~2.5 km of relief exposing ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic gneisses and migmatites that began to exhume ~8 Ma in a zone of continental extension 120 km west of the tip of the westward propagating Woodlark seafloor spreading. Two previous models for the origin and emplacement of the gneiss domes include: 1) the domes are metamorphic core complexes formed as footwall blocks on north-dipping, low-angle (<30 deg.) normal faults of Plio-Pleistocene age; and 2) the domes are diapirs of buoyant lower crustal material extruding vertically through narrow zones of extension (~30 km wide) in an overlying dense layer of ultramafic rock. To study the style of continental extension accompanying exhumation of the DEI gneiss domes, we interpreted a loose grid of 1,518 km of 2-D multi-channel seismic (MCS) reflection data and well data from the offshore areas surrounding the DEI, including the Trobriand basin and the Goodenough basin. MCS and well data show the Trobriand basin initially formed as an asymmetrical Miocene forearc basin overlying the south-dipping Trobriand subduction zone that underwent a late Miocene (~11-9 Ma) inversion event that deformed and uplifted the basin's southern and northern margins. Since extension began 8 Ma, the Trobriand basin has evolved as a symmetrical sag basin with 1-3 km of subsidence and few normal faults deforming the upper crust. The Goodenough basin to the south of the Trobriand basin formed as an asymmetrical and southward-tilted half-graben whose master normal fault is the Owen-Stanley fault zone (OSFZ) along the southern edge of the basin. Reconstruction on this structure based on the geometry of faults in the hanging wall indicates a minimum slip on the order of 10 km along a listric fault plane shallowly dipping to the north. The western extension of the OSFZ dips 18 deg. to 24 deg. north along the northern edge of the

  17. Blue Mountain and The Gas Rocks: Rear-Arc Dome Clusters on the Alaska Peninsula

    USGS Publications Warehouse

    Hildreth, Wes; Fierstein, Judy; Calvert, Andrew T.

    2007-01-01

    Behind the single-file chain of stratovolcanoes on the Alaska Peninsula, independent rear-arc vents for mafic magmas are uncommon, and for silicic magmas rarer still. We report here the characteristics, compositions, and ages of two andesite-dacite dome clusters and of several nearby basaltic units, all near Becharof Lake and 15 to 20 km behind the volcanic front. Blue Mountain consists of 13 domes (58-68 weight percent SiO2) and The Gas Rocks of three domes (62-64.5 weight percent SiO2) and a mafic cone (52 weight percent SiO2). All 16 domes are amphibole-biotite-plagioclase felsite, and nearly all are phenocryst rich and quartz bearing. Although the two dome clusters are lithologically and chemically similar and only 25 km apart, they differ strikingly in age. The main central dome of Blue Mountain yields an 40Ar/39Ar age of 632?7 ka, and two of the Gas Rocks domes ages of 25.7?1.4 and 23.3?1.2 ka. Both clusters were severely eroded by glaciation; surviving volumes of Blue Mountain domes total ~1 km3, and of the Gas Rocks domes 0.035 km3. Three basaltic vents lie close to The Gas Rocks, another lies just south of Blue Mountain, and a fifth is near the north shore of Becharof Lake. A basaltic andesite vent 6 km southeast of The Gas Rocks appears to be a flank vent of the arc-front center Mount Peulik. The basalt of Ukinrek Maars has been called transitionally alkalic, but all the other basaltic rocks are subalkaline. CO2-rich gas emissions near the eponymous Gas Rocks domes are not related to the 25-ka dacite dome cluster but, rather, to intracrustal degassing of intrusive basalt, one batch of which erupted 3 km away in 1977. The felsic and mafic vents all lie along or near the Bruin Bay Fault where it intersects a broad transverse structural zone marked by topographic, volcanologic, and geophysical discontinuities.

  18. Gas-controlled seafloor doming on Opouawe Bank, offshore New Zealand

    NASA Astrophysics Data System (ADS)

    Koch, Stephanie; Berndt, Christian; Bialas, Joerg; Haeckel, Matthias; Crutchley, Gareth; Papenberg, Cord; Klaeschen, Dirk; Greinert, Jens

    2015-04-01

    The process of gas accumulation and subsequent sediment doming appears to be a precursory process in the development of methane seep sites on Opouawe Bank and might be a common characteristic for gas seeps in general. Seabed domes appear as unimpressive topographic highs with diameters ranging from 10-1000 m and exhibit small vertical displacements and layer thickness in comparison to their width. The dome-like uplift of the sediments results from an increase in pore pressure caused by gas accumulation in near-seabed sediments. In this context sediment doming is widely discussed to be a precursor of pockmark formation. Our results suggest that by breaching of domed seafloor sediments a new seep site can develop and contrary to ongoing discussion does not necessarily lead to the formation of pockmarks. There are clear differences in individual gas migration structures that indicate a progression through different evolutionary stages, which range from channeled gas flow and associated seismic blanking, to gas trapping beneath relatively low-permeability horizons, and finally overpressure accumulation and doming. We present high resolution sub-bottom profiler (Parasound) and 2D multichannel seismic data from Opouawe Bank, an accretionary ridge at the Hikurangi Margin, offshore New Zealand's North Island. Beneath this bank, methane migrates along stratigraphic pathways from a maximum source depth of 1500-2100 mbsf (meter below seafloor) towards active cold seeps at the seafloor. We show that, in the shallow sediment of the upper 100 mbsf, this primary migration mechanism changes into a process of gas accumulation leading to sediment doming. Modeling the height of the gas column necessary to create different dome geometries, shows that doming due to gas accumulation is feasible and consistent with field observations. The well-stratified, sub-horizontal strata that exist beneath Opouawe Bank provide favorable conditions for this type of seep development because shallow

  19. Structure and evolution of an active resurgent dome evidenced by geophysical investigations: The Yenkahe dome-Yasur volcano system (Siwi caldera, Vanuatu)

    NASA Astrophysics Data System (ADS)

    Brothelande, E.; Lénat, J.-F.; Chaput, M.; Gailler, L.; Finizola, A.; Dumont, S.; Peltier, A.; Bachèlery, P.; Barde-Cabusson, S.; Byrdina, S.; Menny, P.; Colonge, J.; Douillet, G. A.; Letort, J.; Letourneur, L.; Merle, O.; Di Gangi, F.; Nakedau, D.; Garaebiti, E.

    2016-08-01

    In this contribution, we focus on one of the most active resurgences on Earth, that of the Yenkahe dome in the Siwi caldera (Tanna Island, Vanuatu), which is associated with the persistently active Yasur volcano. Gravity and magnetic surveys have been carried out over the past few years in the area, as well as electrical methods including electrical resistivity tomography (ERT), time domain electro-magnetics (TDEM) and self-potential (SP). These investigations were completed by thermometry, CO2 soil gas measurements, field observations and sampling. This multi-method approach allows geological structures within the caldera to be identified, as well as associated hydrothermal features. The global structure of the caldera is deduced from gravity data, which shows the caldera rim as a high density structure. Large lava fields, emplaced before and after the onset of resurgence, are evidenced by combined gravity, magnetic and resistivity signals. In the middle of the caldera, the Yenkahe dome apparently results from a combination of volcanic and tectonic events, showing that lava extrusion and resurgence have been operating simultaneously or alternately during the Siwi caldera post-collapse history. There is a clear distinction between the western and eastern parts of the dome. The western part is older and records the growth of an initial volcanic cone and the formation of a small caldera. This small caldera (paleo-Yasur caldera), partially filled with lava flows, is the present-day focus of volcanic activity and associated fluid circulation and alteration. The eastern part of the dome is presumably younger, and is characterized by intense, extensive hydrothermal alteration and activity. Its northern part is covered by lava flow piles and exhibits a shallow hydrothermal zone in ERT. The southern part has hydrothermal alteration and activity extending at least down to the base of the resurgent dome. This part of the dome is built up of low cohesion rock and is thus

  20. Hard transparent domes and windows from magnesium aluminate spinel

    NASA Astrophysics Data System (ADS)

    DiGiovanni, Anthony A.; Fehrenbacher, Larry; Roy, Don W.

    2005-05-01

    Transparent magnesium aluminate spinel is an attractive material for use in a wide range of optical applications including windows, domes, armor, and lenses, which require excellent transmission from the visible through to the mid IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns. Transmission characteristics rival that of ALON and sapphire in the mid-wave IR, making it especially attractive for the everincreasing performance requirements of current and next-generation IR imaging systems. Future designs in missile technology will require materials that can meet stringent performance demands in both optical and RF wavelengths. Loss characteristics for spinel are being investigated to meet those demands. Technology Assessment and Transfer Inc. (TA&T), have established a 9000 ft2 production facility for optical quality spinel based on the traditional hot-pressing followed by hot isostatic pressing (HIPing) route. Additionally, TA&T is developing pressureless sintering - a highly scalable, near net shape processing method based on traditional ceramic processing technology - to fabricate optical components. These two main processing approaches allow the widest variety of applications to be addressed using a range of optical components and configurations. The polycrystalline nature of spinel facilitates near net shape processing, which provides the potential to fabricate physically larger optical parts or larger quantities of parts at significantly lower costs compared to single crystal materials such as sapphire. Current research is focused at optimizing the processing parameters for both synthesis routes to maximize strength and transparency while minimizing the cost of fabrication.

  1. Phytoplankton production and grazing balances in the Costa Rica Dome.

    PubMed

    Landry, Michael R; Selph, Karen E; Décima, Moira; Gutiérrez-Rodríguez, Andrés; Stukel, Michael R; Taylor, Andrew G; Pasulka, Alexis L

    2016-03-01

    We investigated phytoplankton production rates and grazing fates in the Costa Rica Dome (CRD) during summer 2010 based on dilution depth profiles analyzed by flow cytometry and pigments and mesozooplankton grazing assessed by gut fluorescence. Three community production estimates, from (14)C uptake (1025 ± 113 mg C m(-2) day(-1)) and from dilution experiments analyzed for total Chla (990 ± 106 mg C m(-2) day(-1)) and flow cytometry populations (862 ± 71 mg C m(-2) day(-1)), exceeded regional ship-based values by 2-3-fold. Picophytoplankton accounted for 56% of community biomass and 39% of production. Production profiles extended deeper for Prochlorococcus (PRO) and picoeukaryotes than for Synechococcus (SYN) and larger eukaryotes, but 93% of total production occurred above 40 m. Microzooplankton consumed all PRO and SYN growth and two-third of total production. Positive net growth of larger eukaryotes in the upper 40 m was balanced by independently measured consumption by mesozooplankton. Among larger eukaryotes, diatoms contributed ∼3% to production. On the basis of this analysis, the CRD region is characterized by high production and grazing turnover, comparable with or higher than estimates for the eastern equatorial Pacific. The region nonetheless displays characteristics atypical of high productivity, such as picophytoplankton dominance and suppressed diatom roles.

  2. Phytoplankton production and grazing balances in the Costa Rica Dome

    PubMed Central

    Landry, Michael R.; Selph, Karen E.; Décima, Moira; Gutiérrez-Rodríguez, Andrés; Stukel, Michael R.; Taylor, Andrew G.; Pasulka, Alexis L.

    2016-01-01

    We investigated phytoplankton production rates and grazing fates in the Costa Rica Dome (CRD) during summer 2010 based on dilution depth profiles analyzed by flow cytometry and pigments and mesozooplankton grazing assessed by gut fluorescence. Three community production estimates, from 14C uptake (1025 ± 113 mg C m−2 day−1) and from dilution experiments analyzed for total Chla (990 ± 106 mg C m−2 day−1) and flow cytometry populations (862 ± 71 mg C m−2 day−1), exceeded regional ship-based values by 2–3-fold. Picophytoplankton accounted for 56% of community biomass and 39% of production. Production profiles extended deeper for Prochlorococcus (PRO) and picoeukaryotes than for Synechococcus (SYN) and larger eukaryotes, but 93% of total production occurred above 40 m. Microzooplankton consumed all PRO and SYN growth and two-third of total production. Positive net growth of larger eukaryotes in the upper 40 m was balanced by independently measured consumption by mesozooplankton. Among larger eukaryotes, diatoms contributed ∼3% to production. On the basis of this analysis, the CRD region is characterized by high production and grazing turnover, comparable with or higher than estimates for the eastern equatorial Pacific. The region nonetheless displays characteristics atypical of high productivity, such as picophytoplankton dominance and suppressed diatom roles. PMID:27275036

  3. VLF electromagnetic investigations of the crater and central dome of Mount St. Helens, Washington

    USGS Publications Warehouse

    Towle, J.N.

    1983-01-01

    A very low frequency (VLF) electromagnetic induction survey in the crater of Mount St. Helens has identified several electrically conductive structures that appear to be associated with thermal anomalies and ground water within the crater. The most interesting of these conductive structures lies beneath the central dome. It is probably a partial melt of dacite similar to that comprising the June 1981 lobe of the central dome. ?? 1983.

  4. Results of water quality sampling near Richton, Cypress Creek and Lampton Salt Domes, Mississippi

    USGS Publications Warehouse

    Gandl, L.A.; Spiers, C.A.

    1980-01-01

    In the Mississippi salt basin in southern Mississippi, chemical quality studies of surface water and ground water have been made to determine present water-quality conditions near three salt domes being studied by the Department of Energy as potential repositories for radioactive wastes. Chloride concentrations in excess of 60 milligrams per liter in surface water and ground water in Perry County indicate that contamination could be occurring from industrial wastes, oil test wells, or dissolution of Richton or Cypress Creek domes. (USGS)

  5. Characteristics, distribution and geologic/terrain associations of small dome-like hills on Venus

    NASA Technical Reports Server (NTRS)

    Aubele, J. C.; Slyuta, E. N.

    1989-01-01

    Approximately 22,000 small dome-like hills were recognized on the northern 20 percent of the surface of Venus imaged by Verera 15/16. These features were described as generally circular in planimetric outline, with a range in basal diameter from the effective resolution of the Venera images (1 to 2 km) up to 20 km. The General Characteristics, Dome Distribution and Terrain Unit and Geologic Feature Associations are discussed.

  6. Eruptive Variations During the Emplacement of Cerro Pinto, an Ambitious Rhyolite Dome, Puebla, Mexico

    NASA Astrophysics Data System (ADS)

    Zimmer, B.; Riggs, N.; Carrasco-Nunez, G.

    2006-12-01

    Cerro Pinto is a rhyolite dome complex located in the eastern Trans-Mexican Volcanic Belt. The complex is composed of four tuff rings and four domes that were emplaced in three distinct eruptive stages marked by changes in vent location and eruptive character. Each of these stages contained eruptive sequences that follow simple rhyolite-dome models, in which a pyroclastic phase is followed immediately by effusive dome emplacement. However, some aspects of the eruptive history, such as the occurrence of explosive reactivation and dome destruction through a lateral blast are uncommon in small rhyolitic structures and are more commonly associated with polygenetic structures, such as stratovolcanoes or calderas. In these larger structures, new pulses of magma often initiate reactivation, but at Cerro Pinto the story is different. Major and trace element geochemistry suggest that Cerro Pinto was sourced by a small, isolated magma chamber, unassociated with any surrounding silicic centers and did not experience any change in chemical composition over the course of the eruption. Based on these data and field observations, it is inferred that Cerro Pinto's eruptive variations were not the result of the influx of a new magma batch, but were the result of both phreatomagmatic interactions and the presence of a small magma chamber that was zoned with respect to volatiles. Both of these factors are commonly encountered in volcanologic studies, but documentation of their influence on smaller structures is under represented. Rhyolite domes have long been considered relatively simple volcanic structures with only localized hazard implications. However, the eruptive variations displayed by Cerro Pinto suggest that isolated rhyolite dome evolutions can be much more complex with the potential for explosive reactivation and dome collapse; events that must be taken into consideration when making hazard assessments.

  7. Three-dimensional representations of salt-dome margins at four active strategic petroleum reserve sites.

    SciTech Connect

    Rautman, Christopher Arthur; Stein, Joshua S.

    2003-01-01

    Existing paper-based site characterization models of salt domes at the four active U.S. Strategic Petroleum Reserve sites have been converted to digital format and visualized using modern computer software. The four sites are the Bayou Choctaw dome in Iberville Parish, Louisiana; the Big Hill dome in Jefferson County, Texas; the Bryan Mound dome in Brazoria County, Texas; and the West Hackberry dome in Cameron Parish, Louisiana. A new modeling algorithm has been developed to overcome limitations of many standard geological modeling software packages in order to deal with structurally overhanging salt margins that are typical of many salt domes. This algorithm, and the implementing computer program, make use of the existing interpretive modeling conducted manually using professional geological judgement and presented in two dimensions in the original site characterization reports as structure contour maps on the top of salt. The algorithm makes use of concepts of finite-element meshes of general engineering usage. Although the specific implementation of the algorithm described in this report and the resulting output files are tailored to the modeling and visualization software used to construct the figures contained herein, the algorithm itself is generic and other implementations and output formats are possible. The graphical visualizations of the salt domes at the four Strategic Petroleum Reserve sites are believed to be major improvements over the previously available two-dimensional representations of the domes via conventional geologic drawings (cross sections and contour maps). Additionally, the numerical mesh files produced by this modeling activity are available for import into and display by other software routines. The mesh data are not explicitly tabulated in this report; however an electronic version in simple ASCII format is included on a PC-based compact disk.

  8. Transformation characteristics of organic pollutants in Fered-Fenton process for dry-spun acrylic fiber wastewater treatment.

    PubMed

    Wei, Jian; Song, Yonghui; Meng, Xiaoguang; Tu, Xiang; Pic, Jean-Stéphane

    2014-01-01

    The Fered-Fenton process using Ti sheet as cathode and RuO2/Ti as anode was employed for the pretreatment of dry-spun acrylic fiber manufacturing wastewater. The effects of feeding mode and concentration of H2O2 on chemical oxygen demand (COD) removal efficiency as well as the biodegradability variation during the Fered-Fenton process were investigated. The feeding mode of H2O2 had significant influence on COD removal efficiency: the removal efficiency was 44.8% if all the 60.0 mM H2O2 was fed at once, while it could reach 54.1% if the total H2O2 was divided into six portions and fed six times. The biochemical oxygen demand/COD ratio increased from 0.29 to above 0.68 after 180 min treatment. The transformation characteristics of organic pollutants during the Fered-Fenton process were evaluated by using gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR) and fluorescence excitation-emission matrix (EEM) spectroscopy. Most of the refractory organic pollutants with aromatic structure or large molecular weight were decomposed during the Fered-Fenton process.

  9. Magnetic AC susceptibility study of the cobalt segregation process in melt-spun Cu-Co alloys

    NASA Astrophysics Data System (ADS)

    López, A.; Lázaro, F. J.; von Helmolt, R.; García-Palacios, J. L.; Wecker, J.; Cerva, H.

    1998-08-01

    Temperature and frequency-dependent AC susceptibility has been used to characterize Cu 90Co 10 melt-spun ribbons, about 15 μm thick, in order to see to what extent this technique yields information about the segregation of cobalt in this alloy. The interpretation of the results includes, as a prerequisite, a transmission electron microscopy (TEM) characterization and makes use of previous field-dependent magnetization data on the same samples. Due to their different dynamical magnetic properties, the large intergrain precipitates, the small intragrain aggregates and the remaining Cu-Co solid solution, previously detected in these alloys, are independently observed by AC susceptibility as ferromagnetic, superparamagnetic and spin-glass species. Contrary to other, mostly local, microstructural characterization techniques of use with nanostructured materials, the AC susceptibility yields information about the whole sample. Furthermore, unlike the measurement of the temperature-dependent magnetization which is the magnetic technique mostly used until now, the results are basically independent of the thermal history. The correlation between microstructure and magnetic properties is illustrated by a scheme which includes magnetization, AC susceptibility and TEM data.

  10. Non-linear elasticity of core/shell spun PGS/PLLA fibres and their effect on cell proliferation.

    PubMed

    Xu, Bing; Rollo, Ben; Stamp, Lincon A; Zhang, Dongcheng; Fang, Xiya; Newgreen, Donald F; Chen, Qizhi

    2013-09-01

    An efficient delivery system is critical for the success of cell therapy. To deliver cells to a dynamic organ, the biomaterial vehicle should mechanically match with the non-linearly elastic host tissue. In this study, non-linearly elastic biomaterials have been fabricated from a chemically crosslinked elastomeric poly(glycerol sebacate) (PGS) and thermoplastic poly(l-lactic acid) (PLLA) using the core/shell electrospinning technique. The spun fibrous materials containing a PGS core and PLLA shell demonstrate J-shaped stress-strain curves, having ultimate tensile strength (UTS), rupture elongation and stiffness constants of 1 ± 0.2 MPa, 25 ± 3% and 12 ± 2, respectively, which are comparable to skin tissue properties reported previously. Our ex vivo and in vivo trials have shown that the elastomeric mesh supports and fosters the growth of enteric neural crest (ENC) progenitor cells, and that the cell-seeded elastomeric fibrous sheet physically remains in intimate contact with guts after grafting, providing the effective delivery of the progenitor cells to an embryonic and post-natal gut environment.

  11. Polyurethane/Cotton/Carbon Nanotubes Core-Spun Yarn as High Reliability Stretchable Strain Sensor for Human Motion Detection.

    PubMed

    Wang, Zifeng; Huang, Yan; Sun, Jinfeng; Huang, Yang; Hu, Hong; Jiang, Ruijuan; Gai, Weiming; Li, Guangming; Zhi, Chunyi

    2016-09-21

    Smart yarns and textiles are an active field of researches nowadays due to their potential applications in flexible and stretchable electronics, wearable devices, and electronic sensors. Integration of ordinary yarns with conductive fillers renders the composite yarns with new intriguing functions, such as sensation and monitoring of strain and stress. Here we report a low cost scalable fabrication for highly reliable, stretchable, and conductive composite yarn as effective strain sensing material for human motion monitoring. By incorporating highly conductive single-wall carbon nanotubes (SWCNTs) into the elastic cotton/polyurethane (PU) core-spun yarn through a self-designed coating approach, we demonstrated that the yarn is able to detect and monitor the movement of human limbs, such as finger and elbow, and even the wink of eyes. By virtue of the covered structure of the cotton/PU yarn and the reinforcement effect of SWCNTs, the composite yarn can bear up to 300% strain and could be cycled nearly 300,000 times under 40% strain without noticeable breakage. It is promising that this kind of conductive yarn can be integrated into various fabrics and used in future wearable devices and electronic skins.

  12. Design and optimization of a novel bio-loom to weave melt-spun absorbable polymers for bone tissue engineering.

    PubMed

    Gilmore, Jordon; Burg, Timothy; Groff, Richard E; Burg, Karen J L

    2016-05-05

    Bone graft procedures are currently among the most common surgical procedures performed worldwide, but due to high risk of complication and lack of viable donor tissue, there exists a need to develop alternatives for bone defect healing. Tissue engineering, for example, combining biocompatible scaffolds with mesenchymal stem cells to achieve new bone growth, is a possible solution. Recent work has highlighted the potential for woven polymer meshes to serve as bone tissue engineering scaffolds; since, scaffolds can be iteratively designed by adjusting weave settings, material types, and mesh parameters. However, there are a number of material and system challenges preventing the implementation of such a tissue engineering strategy. Fiber compliance, tensile strength, brittleness, cross-sectional geometry, and size present specific challenges for using traditional textile weaving methods. In the current work, two potential scaffold materials, melt-spun poly-l-lactide, and poly-l-lactide-co-ε-caprolactone, were investigated. An automated bio-loom was engineered and built to weave these materials. The bio-loom was used to successfully demonstrate the weaving of these difficult-to-handle fiber types into various mesh configurations and material combinations. The dobby-loom design, adapted with an air jet weft placement system, warp tension control system, and automated collection spool, provides minimal damage to the polymer fibers while overcoming the physical constraints presented by the inherent material structure. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  13. Final report on decommissioning boreholes and wellsite restoration, Gulf Coast Interior Salt Domes of Mississippi

    SciTech Connect

    Not Available

    1989-04-01

    In 1978, eight salt domes in Texas, Louisiana, and Mississippi were identified for study as potential locations for a nuclear waste repository as part of the National Waste Terminal Storage (NWTS) program. Three domes were selected in Mississippi for ``area characterization`` phase study as follows: Lampton Dome near Columbia, Cypress Creek Dome near New Augusta, and Richton Dome near Richton. The purpose of the studies was to acquire geologic and geohydrologic information from shallow and deep drilling investigations to enable selection of sites suitable for more intensive study. Eleven deep well sites were selected for multiple-well installations to acquire information on the lithologic and hydraulic properties of regional aquifers. In 1986, the Gulf Coast salt domes were eliminated from further consideration for repository development by the selection of three candidate sites in other regions of the country. In 1987, well plugging and restoration of these deferred sites became a closeout activity. The primary objectives of this activity are to plug and abandon all wells and boreholes in accordance with state regulations, restore all drilling sites to as near original condition as feasible, and convey to landowners any wells on their property that they choose to maintain. This report describes the activities undertaken to accomplish these objectives, as outlines in Activity Plan 1--2, ``Activity Plan for Well Plugging and Site Restoration of Test Hole Sites in Mississippi.``

  14. Reconnaissance and deep-drill site selection on Taylor Dome, Antarctica

    NASA Technical Reports Server (NTRS)

    Grootes, Pieter M.; Waddington, Edwin D.

    1993-01-01

    Taylor Dome is a small ice dome near the head of Taylor Valley, Southern Victoria Land. The location of the dome, just west of the Transantarctic Mountains, is expected to make the composition of the accumulating snow sensitive to changes in the extent of the Ross Ice Shelf. Thus, it is linked to the discharge of the West Antarctic Ice Sheet but protected against direct influences of glacial-interglacial sea-level rise. The record of past climatic and environmental changes in the ice provides a valuable complement to the radiocarbon-dated proxy record of climate derived from perched deltas, strandlines, and moraines that have been obtained in the nearby Dry Valleys. We carried out a reconnaissance of the Taylor Dome area over the past two field seasons to determine the most favorable location to obtain a deep core to bedrock. A stake network has been established with an 80-km line roughly along the crest of Taylor Dome, and 40-km lines parallel to it and offset by 10 km. These lines have been surveyed 1990/91, and the positions of 9 grid points have been determined with geoceivers. A higher density stake network was placed and surveyed around the most likely drill area in the second year. Ground-based radar soundings in both years provided details on bedrock topography and internal layering of the ice in the drill area. An airborne radar survey in January 1992, completed the radar coverage of the Taylor Dome field area.

  15. Potential field constraints on the deep structure of the Lugo gneiss dome (NW Spain)

    NASA Astrophysics Data System (ADS)

    Ayarza, Puy; Martínez Catalán, José R.

    2007-07-01

    The Lugo gneiss dome, in the NW Iberian Massif (Spain) is a Variscan structure developed during late stages of orogenic collapse. Crustal extension was mainly accomplished by two kilometre-scale conjugate extensional shear zones and by the late development of the dome and a huge normal fault. These structures overprint previous contractional recumbent folds and a thrust fault. The Lugo dome and its southward continuation, the Sanabria dome, are the site of the conspicuous Eastern Galicia Magnetic Anomaly (EGMA), a N-S band, 50 km wide and 190 km long, with a maximum amplitude of 190 nT. Integrated potential field modelling of the EGMA and its corresponding gravity signature have been carried out aided by constraints provided by the measurement of c. 900 magnetic susceptibilities and by previous geophysical data, mainly seismic refraction and reflection profiles. Results suggest that a large volume of low-density migmatites and associated inhomogeneous granites are the main source of the magnetic anomaly. Small massifs of basic and ultrabasic rocks inside the migmatites and high-susceptibility iron ore bodies sparsely distributed in low-grade Middle Ordovician slates are also thought to contribute to the anomaly but to a minor extent. Although otherwise similar to other gneiss domes, the Lugo dome is accompanied by a striking magnetic anomaly whose origin is discussed in terms of the tectonic evolution of this structure and the provenance of the magnetite-bearing migmatites and inhomogeneous granites that core it.

  16. Percutaneous Ethanol Injection via an Artificially Induced Right Hydrothorax for Hepatocellular Carcinoma in the Hepatic Dome

    SciTech Connect

    Kume, Akimichi Nimura, Yuji; Kamiya, Junichi; Nagino, Masato; Kito, Yasushi

    2003-11-15

    To evaluate the efficacy of sonographically (US) guided percutaneous ethanol injection (PEI) via an artificially induced right hydrothorax (transthoracic PEI) to treat US-invisible hepatocellular carcinoma (HCC) in the hepatic dome. Five cirrhotic patients with US-invisible HCC in the hepatic dome, who were poor surgical candidates, underwent transthoracic PEI. An artificial right hydrothorax was created by instilling 500 ml saline, and absolute ethanol was injected transhydrothoracically into the hepatic dome lesion under local anesthesia. The success and complications were assessed radiologically. The patients were followed up serologically and radiologically for 12-44 (mean 28.4) months. Twenty-five hydrothoraces were induced. All hydrothoraces enabled US visualization of the entire hepatic dome. Eight of the nine small lesions were treated successfully by the treatment. Two of the three local recurrences were eradicated by repeat transthoracic PEI. One large lesion was treated by a combination of transthoracic and regular PEI. The only complication was one clinically insignificant pneumothorax. Induction of a right hydrothorax is feasible and safe. The hydrothorax enables US visualization of the entire hepatic dome and permits US-guided PEI for HCC in the hepatic dome that otherwise would not be possible.

  17. The Effectiveness of Modified Vertical Dome Division Technique in Reducing Nasal Tip Projection in Rhinoplasty

    PubMed Central

    Gandomi, Behrooz; Arzaghi, Mohammad Hossein; Rafatbakhsh, Mohammad

    2011-01-01

    Background: The technique of vertical dome division or tip defining, involves incising the lateral crura and vestibular skin at or lateral to the dome or tip defining point. The incision divides the lower lateral cartilage into a lateral segment and a medial segment, which are advanced anteriorly and sutured together to increase tip projection. The present study aimed at assessing a new vertical dome division, which is a modified version of vertical dome technique to decrease nasal tip projection, and increase or decrease nasal tip rotation and other tip deformities. Methods: The medical files of patients undergone rhinoplasty from 2003 to 2008 were retrospectively analyzed. The files were selected from a computerized rhinoplasty database of patients, who had been operated using a modified vertical dome technique and followed-up for one year or more after the surgery. Results: A total of 3756 patients were operated. Complications related to the nasal tip such as bossae, bifidity, persistent tip projection or tip asymmetry was seen in 81 patients (2.1%). Revisions for tip-related problems were performed in 42 patients (1.1%). Conclusions: The findings suggest that the modified vertical dome technique is an effective method for nasal tip deprojection and narrowing via an open approach. The length of follow-up and the large sample size support effectiveness of the technique. PMID:23359623

  18. Effect of boron additions on phase formation and magnetic properties of TbCu7-type melt spun SmFe ribbons

    NASA Astrophysics Data System (ADS)

    Zheng, Chuanjiang; Yu, Dunbo; Li, Kuoshe; Luo, Yang; Jin, Jinling; Lu, Shuo; Li, Hongwei; Mao, Yongjun; Quan, Ningtao

    2016-08-01

    Melt spun ribbons of a series of SmFe12Bx (x=0.0, 0.5, 0.75, 1.0, 1.25, and 1.5) have been prepared by the melt spinning technique. Sm-Fe-B melt spun ribbons with single phase TbCu7-type structure were prepared from the SmFe12Bx (x=0.5, 0.75, and 1.0) alloys at the surface velocity around 40 m/s. The addition of boron not only inhibits the appearance of soft magnetic phase α-Fe, but also enhances the ability of amorphous formation for melt spun Sm-Fe ribbons. The concentration of boron atoms, however, exceeds the limit of the solubility (x>1.0) of Sm-Fe alloys, which does not impede the appearance of α-Fe but accelerates the formation of metastable phase Sm2Fe23B3 that is unfavorable to their magnetic properties. Moreover, it is found that the addition of boron whose concentration is 0.0≤x≤0.75 can stabilize the metastable TbCu7-type structure because of the increase of the lattice parameter ratio c/a. The magnetic properties of as-annealed SmFe12B1.0 melt spun ribbons with an energy product of 2.19MGOe, a coercivity of 2.36 kOe and a remanence of 4.8 kGs have been achieved. The microstructural characteristics of as-annealed melt spun SmFe12 and SmFe12B1.0 ribbons have been discussed as well. The following sequence of the hyperfine field H(6l)

  19. Postural Control Disturbances Produced By Exposure to HMD and Dome Vr Systems

    NASA Technical Reports Server (NTRS)

    Harm, D. L.; Taylor, L. C.

    2005-01-01

    Two critical and unresolved human factors issues in VR systems are: 1) potential "cybersickness", a form of motion sickness which is experienced in virtual worlds, and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Most astronauts and cosmonauts experience perceptual and sensorimotor disturbances during and following space flight. All astronauts exhibit decrements in postural control following space flight. It has been suggested that training in virtual reality (VR) may be an effective countermeasure for minimizing perceptual and/or sensorimotor disturbances. People adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, and experimentally-produced stimulus rearrangements (e.g., reversing prisms, magnifying lenses, flight simulators, and VR systems). Adaptation is revealed by aftereffects including perceptual disturbances and sensorimotor control disturbances. The purpose of the current study was to compare disturbances in postural control produced by dome and head-mounted virtual environment displays. Individuals recovered from motion sickness and the detrimental effects of exposure to virtual reality on postural control within one hour. Sickness severity and initial decrements in postural equilibrium decreases over days, which suggests that subjects become dual-adapted over time. These findings provide some direction for developing training schedules for VR users that facilitate adaptation, and address safety concerns about aftereffects.

  20. Fast neutrons measured in copper from the Hiroshima atomic bomb dome.

    PubMed

    Marchetti, A A; McAninch, J E; Rugel, G; Rühm, W; Korschinek, G; Martinelli, R E; Faestermann, T; Knie, K; Egbert, S D; Wallner, A; Wallner, C; Tanaka, K; Endo, S; Hoshi, M; Shizuma, K; Fujita, S; Hasai, H; Imanaka, T; Straume, T

    2009-01-01

    The first measurements of (63)Ni produced by A-bomb fast neutrons (above approximately 1 MeV) in copper samples from Hiroshima encompassed distances from approximately 380 to 5062 m from the hypocenter (the point on the ground directly under the bomb). They included the region of interest to survivor studies (approximately 900 to 1500 m) and provided the first direct validation of fast neutrons in that range. However, a significant measurement gap remained between the hypocenter and 380 m. Measurements close to the hypocenter are important as a high-value anchor for the slope of the curve for neutron activation as a function of distance. Here we report measurements of (63)Ni in copper samples from the historic Hiroshima Atomic Bomb Dome, which is located approximately 150 m from the hypocenter. These measurements extend the range of our previously published data for (63)Ni providing a more comprehensive and consistent A-bomb activation curve. The results are also in good agreement with calculations based on the current dosimetry system (DS02) and give further experimental support to the accuracy of this system that forms the basis for radiation risk estimates worldwide.

  1. Strain-collapsed metamorphic isograds in a sillimanite gneiss dome, Seward Peninsula, Alaska

    SciTech Connect

    Miller, E.L.; Calvert, A.T.; Little, T.A. )

    1992-06-01

    Unusually closely spaced Barrovian series isograds have been described along the flanks of the Kigluaik Mountains, Seward Peninsula, Alaska, where they separate a high-grade gneiss complex intruded by granites of Cretaceous age from surrounding, regionally developed, blueschist to greenschist facies rocks. Structural mapping of the transition zone between the two metamorphic types indicates that their juxtaposition was aided by significant syn- to late-metamorphic solid-state flow that served to attenuate the overlying rock column and thus collapse the field metamorphic gradient. On the basis of field relations, structural data, petrography, and geochronologic data, strain appears to have accompanied the rapid (adiabatic) rise of high-temperature rocks from several tens of kilometers to less than 10 km depth during the Cretaceous, in an event younger than the unrelated to high-P metamorphism. Granite-cored gneiss domes on the Seward Peninsula may have formed during extension of previously thickened continental crust, resulting in the {approximately}35-km-thick crust and near-sea-level elevations of the region today.

  2. Structural analysis of the collar of the Vredefort Dome, South Africa—Significance for impact-related deformation and central uplift formation

    NASA Astrophysics Data System (ADS)

    Wieland, Frank; Gibson, Roger L.; Reimold, Wolf Uwe

    2005-10-01

    Landsat TM, aerial photograph image analysis, and field mapping of Witwatersrand supergroup meta-sedimentary strata in the collar of the Vredefort Dome reveals a highly heterogeneous internal structure involving folds, faults, fractures, and melt breccias that are interpreted as the product of shock deformation and central uplift formation during the 2.02 Ga Vredefort impact event. Broadly radially oriented symmetric and asymmetric folds with wavelengths ranging from tens of meters to kilometers and conjugate radial to oblique faults with strike-slip displacements of, typically, tens to hundreds of meters accommodated tangential shortening of the collar of the dome that decreased from ˜17% at a radius from the dome center of 21 km to <5% at a radius of 29 km. Ubiquitous shear fractures containing pseudotachylitic breccia, particularly in the metapelitic units, display local slip senses consistent with either tangential shortening or tangential extension; however, it is uncertain whether they formed at the same time as the larger faults or earlier, during the shock pulse. In addition to shatter cones, quartzite units show two fracture types—a cmspaced rhomboidal to orthogonal type that may be the product of shock-induced deformation and later joints accomplishing tangential and radial extension. The occurrence of pseudotachylitic breccia within some of these later joints, and the presence of radial and tangential dikes of impact melt rock, confirm the impact timing of these features and are suggestive of late-stage collapse of the central uplift.

  3. 238U-230Th crystallization ages for the oldest domes of the Mono Craters, eastern California

    NASA Astrophysics Data System (ADS)

    Marcaida, M.; Vazquez, J. A.

    2014-12-01

    The Mono Craters volcanic chain is one of the youngest areas of rhyolitic volcanism in the Mono Lake-Long Valley region of eastern California. Located just south of Mono Lake, the Mono Craters comprise at least 28 individual domes and flows (numbered 3-30, north to south); however, the timing and frequency of eruptions remain poorly resolved. The earliest signs of volcanic activity are preserved as numerous tephra layers (Ashes 1-19, top to bottom) in the late Pleistocene Wilson Creek formation of ancestral Mono Lake, which indicate that rhyolitic volcanism from Mono Craters began by at least ca. 62 ka [1]. Although the current chronology indicates that most of the Mono Craters are younger than ca. 20 ka [2-4], similar compositions of titanomagnetite from both pumice and lava potentially correlate several Wilson Creek tephras to porphyritic biotite-bearing domes 11, 24, and 19 of the Mono Craters [5], suggesting that multiple domes in the Mono Craters chain reflect volcanism older than ca. 20 ka. Ash 3 is correlated to dome 11 based on similar ca. 20 ka ages and titanomagnetite compositions [6]. More recently, we performed ion microprobe 238U-230Th dating of unpolished rims of allanite and zircon from domes 24 and 19, yielding isochron ages of ca. 38 ka and ca. 42 ka, respectively. The age of dome 24 is consistent with the ca. 38 ka age of its potential correlative tephra layers [1, 5], indicating that dome 24 is likely the extrusive equivalent of Ashes 9-10. Dome 19 has titanomagnetite crystals with similar bimodal chemistry to titanomagnetites from Ash 15 [5]. The age of dome 19 is indistinguishable from the 238U-230Th age of Ash 15 [1], which erupted during a prominent geomagnetic excursion, originally designated as the "Mono Lake" excursion. Combining geochronological and titanomagnetite compositional data confirms that Ash 15 and its extrusive equivalent, dome 19, erupted during the Laschamp excursion. [1] Vazquez, J.A. and Lidzbarski, M.I. (2012) EPSL 357

  4. Venus steep-sided domes: Relationships between geological associations and possible petrogenetic models

    NASA Technical Reports Server (NTRS)

    Pavri, B.; Head, James W., III

    1992-01-01

    Venus domes are characterized by steep sides, a circular shape, and a relatively flat summit area. In addition, they are orders of magnitude larger in volume and have a lower height/diameter ratio than terrestrial silicic lava domes. The morphology of the domes is consistent with formation by lava with a high apparent viscosity. Twenty percent of the domes are located in or near tessera (highly deformed highlands), while most other (62 percent) are located in and near coronae (circular deformational features thought to represent local mantle upwelling). These geological associations provide evidence for mechanisms of petrogenesis and several of these models are found to be plausible: remelting of basaltic or evolved crust, differentiation of basaltic melts, and volatile enhancement and eruption of basaltic foams. Hess and Head have shown that the full range of magma compositions existing on the Earth is plausible under various environmental conditions on Venus. Most of the Venera and Vego lander compostional data are consistent with tholeiitic basalt; however, evidence for evolved magmas was provided by Venera 8 data consistent with a quartz monzonite composition. Pieters et al. have examined the color of the Venus surface from Venera lander images and interpret the surface there to be oxidized. Preliminary modeling of dome growth has provided some interpretations of lava rheology. Viscosity values obtained from these models range from 10(exp 14) - 10(exp 17) pa*s, and the yield strength has been calculated to be between 10(exp 4) and 10(exp 6) Pa, consistent with terrestrial silicic rocks. The apparent high viscosity of the dome lavas suggests that the domes have a silicic composition or must augment their viscosity with increased visicularity or crystal content. Sixty-two percent of the Venus domes are associated with coronae, circular features that have been proposed as sites of mantle upwelling, and 20 percent of the domes are located near tessera, relatively

  5. Late Miocene uplift and doming of Madagascar: topographic implications

    NASA Astrophysics Data System (ADS)

    Delaunay, Antoine; Robin, Cecile; Guillocheau, François; Dall'Asta, Massimo; Calves, Gérôme

    2016-04-01

    and (3) a major stepping of dated planation surfaces. (3) The end result of this uplift is a convex up shape pattern for the end Cretaceous surface weathered during Eocene times, creating the present-day dome morphology (with a central plateau) of Madagascar. (4) The amplitude of this uplift can be estimated based on the present-day elevation of Late Eocene lagoonal sediments located 100 km north-east of Toliara and now at an elevation of 900m. If the absolute sea level was around 50 m (Miller et al., 2005) above present-day sea level during Late Eocene times, this means a surface uplift of around 850 m. (5) The mechanism of this uplift has to explain a very long wavelength deformation (x1000 km) necessary due to mantle dynamics. The relationships with the other East African domes (Ethiopia, East Africa, South Africa) are discussed. This study was founded by TOTAL and IFREMER in the frame of the research project PAMELA (Passive Margin Exploration Laboratories).

  6. Eclipsing Binaries From the CSTAR Project at Dome A, Antarctica

    NASA Astrophysics Data System (ADS)

    Yang, Ming; Zhang, Hui; Wang, Songhu; Zhou, Ji-Lin; Zhou, Xu; Wang, Lingzhi; Wang, Lifan; Wittenmyer, R. A.; Liu, Hui-Gen; Meng, Zeyang; Ashley, M. C. B.; Storey, J. W. V.; Bayliss, D.; Tinney, Chris; Wang, Ying; Wu, Donghong; Liang, Ensi; Yu, Zhouyi; Fan, Zhou; Feng, Long-Long; Gong, Xuefei; Lawrence, J. S.; Liu, Qiang; Luong-Van, D. M.; Ma, Jun; Wu, Zhenyu; Yan, Jun; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; Zhang, Tianmeng; Zhu, Zhenxi; Zou, Hu

    2015-04-01

    The Chinese Small Telescope ARray (CSTAR) has observed an area around the Celestial South Pole at Dome A since 2008. About 20,000 light curves in the i band were obtained during the observation season lasting from 2008 March to July. The photometric precision achieves about 4 mmag at i = 7.5 and 20 mmag at i = 12 within a 30 s exposure time. These light curves are analyzed using Lomb-Scargle, Phase Dispersion Minimization, and Box Least Squares methods to search for periodic signals. False positives may appear as a variable signature caused by contaminating stars and the observation mode of CSTAR. Therefore, the period and position of each variable candidate are checked to eliminate false positives. Eclipsing binaries are removed by visual inspection, frequency spectrum analysis, and a locally linear embedding technique. We identify 53 eclipsing binaries in the field of view of CSTAR, containing 24 detached binaries, 8 semi-detached binaries, 18 contact binaries, and 3 ellipsoidal variables. To derive the parameters of these binaries, we use the Eclipsing Binaries via Artificial Intelligence method. The primary and secondary eclipse timing variations (ETVs) for semi-detached and contact systems are analyzed. Correlated primary and secondary ETVs confirmed by false alarm tests may indicate an unseen perturbing companion. Through ETV analysis, we identify two triple systems (CSTAR J084612.64-883342.9 and CSTAR J220502.55-895206.7). The orbital parameters of the third body in CSTAR J220502.55-895206.7 are derived using a simple dynamical model.

  7. Public Education and Outreach Through Full-Dome Video Technology

    NASA Astrophysics Data System (ADS)

    Pollock, John

    2009-03-01

    My long-term goal is to enhance public understanding of complex systems that can be best demonstrated through richly detailed computer graphic animation displayed with full-dome video technology. My current focus is on health science advances that focus on regenerative medicine, which helps the body heal itself. Such topics facilitate science learning and health literacy. My team develops multi-media presentations that bring the scientific and medical advances to the public through immersive high-definition video animation. Implicit in treating the topics of regenerative medicine will be the need to address stem cell biology. The topics are clarified and presented from a platform of facts and balanced ethical consideration. The production process includes communicating scientific information about the excitement and importance of stem cell research. Principles of function are emphasized over specific facts or terminology by focusing on a limited, but fundamental set of concepts. To achieve this, visually rich, biologically accurate 3D computer graphic environments are created to illustrate the cells, tissues and organs of interest. A suite of films are produced, and evaluated in pre- post-surveys assessing attitudes, knowledge and learning. Each film uses engaging interactive demonstrations to illustrate biological functions, the things that go wrong due to disease and disability, and the remedy provided by regenerative medicine. While the images are rich and detailed, the language is accessible and appropriate to the audience. The digital, high-definition video is also re-edited for presentation in other ``flat screen'' formats, increasing our distribution potential. Show content is also presented in an interactive web space (www.sepa.duq.edu) with complementing teacher resource guides and student workbooks and companion video games.

  8. Transiting planet candidates with ASTEP 400 at Dome C, Antarctica

    NASA Astrophysics Data System (ADS)

    Mékarnia, D.; Guillot, T.; Rivet, J.-P.; Schmider, F.-X.; Abe, L.; Gonçalves, I.; Agabi, A.; Crouzet, N.; Fruth, T.; Barbieri, M.; Bayliss, D. D. R.; Zhou, G.; Aristidi, E.; Szulagyi, J.; Daban, J.-B.; Fanteï-Caujolle, Y.; Gouvret, C.; Erikson, A.; Rauer, H.; Bouchy, F.; Gerakis, J.; Bouchez, G.

    2016-11-01

    ASTEP 400, the main instrument of the ASTEP (Antarctica Search for Transiting ExoPlanets) programme, is a 40 cm telescope, designed to withstand the harsh conditions in Antarctica, achieving a photometric accuracy of a fraction of millimagnitude on hourly time-scales for planet-hosting southern bright (R ˜ 12 mag) stars. We review the performances of this instrument, describe its operating conditions, and present results from the analysis of observations obtained during its first three years (2010-2012) of operation, before its repatriation in 2014. During this time, we observed a total of 22 stellar fields (1° × 1° field of view). Each field, in which we measured stars up to magnitude R = 18 mag, was observed continuously during ˜7 to ˜30 d. More than 200 000 frames were recorded and 310 000 stars processed, using an implementation of the optimal image subtraction photometry algorithm. We found 43 planetary transit candidates. 20 of these candidates were observed using spectroscopic follow-ups including four targets classified as good planet candidates. Our results demonstrate that accurate near-continuous photometric observations are achievable from the Concordia station at Dome C in Antarctica, even if we were not able to reach the nominal photometric precision of the instrument. We conducted a correlation analysis between the rms noise and a large number of external parameters and found that source of the ˜1 mmag correlated noise is not obvious and does not depend on a single parameter. However, our analysis provided some hints and guidance to increase the photometric accuracy of the instrument. These improvements should equip any future telescope operating in Antarctica.

  9. Mineralogy and Geochemistry of Dacitic domes and associated Cu- Fe-Au Veins occurences during hydrothermal processes, Yazd Province, Iran

    NASA Astrophysics Data System (ADS)

    Sharifi, R.

    2009-04-01

    The Panah-koh Cu-Fe-Au vein deposit, located 60 km south west of Yazd Province, between Central Iranian Zone and Orumieh-Dokhtar tectnomagmatic belt. The vains result from hydrothermal processes related to a Neogenes volcanism which produced a dacitic to rhyodacitic dome which responsible for most of the altration and mineralization in this area. mineralization occurs in a series of NW-SW trending fault planes and breccia zones in (Early Combrian) and sand stone (Percambrian) rocks. the main ore minerals are Chalcopyrite, Pyrite,Arsenopyrite,Hematite,Limonite,Malachite,Azurite, with Quartz,Calcite,Dolomite,Barite and minor Chlorite as the main qanque phases.The Panah- Koh volcanic domes crystallized from an I-Type magma formed in a volcanic arc setting.the volcanic rocks show geochemical evidence of fractionation of Biotite,Hornblande and Fledspars.altration of the minerals in the host rocks suggests pH<5.5 and oxidized conditions.On variation diagrams, MgO, MnO, TiO2, CaO, P2O5, Fe2O3, display negative correlations suggesting that these volcanic rocks experienced fractionation of early-crystallized Biotite, Magnetite, Apatite and Plagioclase. The concentration of Sr, Ni, Ba and V decrease with increasing SiO2 suggesting fractionation of early formed Biotite, K-Feldspar, Magnetite and Plagioclase. supergene effects, with penetration of surface waters along faults and fractures, has led to the oxidation and leaching of the host rocks and the enrichment of copper. Quartz crystals were deposited as layers in crustification banding and comb structures along the walls of veins or the composition of the mineralizing fluids. shallow level of emplacement and low temprature of magma, shows that the hydrothermal system was not able to form a skarn deposit in the Panah-Koh district.

  10. Permeable structures at Ceboruco lava dome, Mexico: the challenge of upscaling laboratory measurements to field constraint

    NASA Astrophysics Data System (ADS)

    Lamur, Anthony; Lavallee, Yan; De Angelis, Silvio

    2015-04-01

    Lava domes are, in their lifespan, variably permeable volcanic structures. During magma ascent, construction of a permeable network is facilitated by the coalescence of vesicles and fractures, which regulates magma outgassing and control whether eruption proceeds effusively or explosively. Here, we present a combined laboratory and field study of dome rock permeability, focusing on a ca. 19th century lava dome at Ceboruco, Mexico. The lava dome has a perfectly rounded shape with a diameter of ~80 metres and a height of ~35 metres. The dome consists of blocks ranging in size between centimetres and 5 metres, which reveal a range of porous structures: the rocks are commonly dense, but porosity occasionally reach 38%; some blocks are entirely massive, whilst others display tensile and shear fractures. Microscopic analysis reveals and equally intricate fracture networks. Permeability measurements are currently being performed on 4 rocks (with different porosities) in a hydrostatic pressure vessel at confining pressures of 6, 10, 15, 20, 30 and 40 MPa and averaged pore pressure of 5 MPa (with differential of 1 MPa). For each sample, the uniaxial compressive strength will be determined and permeability will be measured on samples, which have undergone fracture damage due to loading at different fractions of the uniaxial compressive strength (e.g., 80%, 90% and 100%). The laboratory study will be complemented by an electrical resistivity survey of the dome structure (to be undertaken this coming February-March 2015). We will optically measure the density of fractures (i.e., spacing), and width. The resistivity study will be performed at different scales (1-200 metres) to assess the extent of fractures in individual blocks as well as through the entire dome and its underlying root. Mesoscale permeability measurements will be attempted by introducing salinated water into cracks on metre-size blocks whilst performing 3D electrical resistivity tomography. We aim to discuss

  11. Impact of hydrothermal alteration on lava dome stability: a numerical modelling approach

    NASA Astrophysics Data System (ADS)

    Detienne, Marie; Delmelle, Pierre

    2016-04-01

    Lava domes are a common feature of many volcanoes worldwide. They represent a serious volcanic hazard as they are prone to repeated collapses, generating devastating debris avalanches and pyroclastic flows. While it has long been known that hydrothermal alteration degrades rock properties and weakens rock mass cohesion and strength, there is still little quantitative information allowing the description of this effect and its consequences for assessing the stability of a volcanic rock mass such as a lava dome. In this study, we use the finite difference numerical model FLAC 3D to investigate the impact of hydrothermal alteration on the stability of a volcanic dome lying on a flat surface. Different hydrothermal alteration distributions were tested to encompass the variability observed in natural lava domes. Rock shear strength parameters (minimum, maximum and mean cohesion "c" and friction angle "φ" values) representative of various degrees of hydrothermal rock alteration were used in the simulations. The model predicts that reduction of the basement rock's shear strength decreases the factor of safety significantly. A similar result is found by increasing the vertical and horizontal extension of hydrothermal alteration in the basement rocks. In addition, pervasive hydrothermal alteration within the lava dome is predicted to exert a strong negative influence on the factor of safety. Through reduction of rock porosity and permeability, hydrothermal alteration may also affect pore fluid pressure within a lava dome. The results of new FLAC 3D runs which simulate the effect of hydrothermal alteration-induced pore pressure changes on lava dome stability will be presented.

  12. Development of the Automatic Seeing Monitor for the Site Testing of Dome A

    NASA Astrophysics Data System (ADS)

    Pei, Chong; Yuan, Xiang-Yan; Chen, Hua-Lin; Zhao, Jian-Lin; Wen, Hai-Kun; Li, Zheng-Yang

    2012-07-01

    The Antarctic site-testing campaigns have shown that Dome C is an excellent astronomical site on the earth, it is better than any of existing mid-latitude astronomical sites in the world, because of its cold and dry weather, low infrared background radiation, continuously observable time as long as 3-4 months, clear and highly transparent atmosphere, low wind speed, and the absence of dust and light pollution. And in the international astronomical community it is generally believed that Dome A with a higher altitude may be better than Dome C as a potential excellent astronomical site. In the past 3 years, although held by the Center for Antarctic Astronomy of Chinese Academy of Sciences, the site testing at Dome A has preliminarily confirmed the many advantages of Dome A as an excellent astronomical site, but the data about the atmospheric seeing, which is an important parameter for assessing the site quality for optical observations, have not been obtained until now. Hence, on the basis of a commercial telescope with the diameter of 35 cm, we have made the hardware reformation and software development to have it operate as a DIMM (Differential Image Motion Monitor), which can simultaneously monitor both the seeing and isoplanatic angle at Dome A automatically. At present this instrument has been shipped to Antarctica by the "Xuelong" exploration ship, and will be installed at Dome A, and begin to work in early 2011. Before the shipment, by through the comparative measurements together with an existing seeing monitor at the Xinglong astronomical station, the software, hardware, as well as the installation and adjustment of the instrument, are further verified by testing.

  13. Mechanical design of a completely open-foldable dome for EST

    NASA Astrophysics Data System (ADS)

    Hammerschlag, Robert H.; Kommers, Johannes N. M.; van Leverink, Simon J.; Bettonvil, Felix C. M.; Visser, Simon; Jägers, Aswin P. L.; Sliepen, Guus

    2010-07-01

    In the context of the EST design study for a 4m-class solar telescope and a study for large open-foldable domes of the Dutch Technology Foundation STW, a design is made for the 20 to 30m diameter range. Detailed designs are made for three specific diameter sizes: 23, 28 and 33m. Smaller-size open-foldable domes based on tensioned cloth and in use at the Dutch Open Telescope (7m) and the GREGOR (9m) have proven to be all-weather stable and very effective for good seeing conditions for solar telescopes. The cloth has shown no degradation over the past 14 (DOT) resp. 6 (GREGOR) years of experience and no permanent elongation with the frequent de-tensioning and tensioning during opening and closing. The application of cloth permits a dome design leaving, when opened, the telescope completely free without any structure over the telescope and no massive structures besides or under it. Basis for the new design is the available prestretched stable cloth, which is nowadays produced in much stronger qualities than used for DOT and GREGOR. The larger curvature radius requires larger tension in the cloth, but combination with stronger cloth fits for the upscaling. Calculations show that the steel construction geometries of the GREGOR dome can be upscaled with a few adjustments. Bearings and drives remain within normal sizes. Cost calculations show that open-foldable domes of this size are remarkably lower in price than closed domes. In addition, an interesting option is presented for a semi-transparent windshield of which the position can be adapted to the wind direction. This shield gives an effective wind protection of the region around the primary mirror without disturbing the wind flows above the shield and without stagnant air or big eddies behind it. It is storm safe and the costs are only a fraction of the open-foldable dome costs.

  14. Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah

    USGS Publications Warehouse

    Jackson, M.D.; Pollard, D.D.

    1990-01-01

    A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85 and 3.0 km, respectively. These mountains record successive stages in the inflation of near-surface diorite intrusions that are probably laccolithic in origin. The host rocks deformed along networks of outcrop-scale faults, or deformation bands, marked by crushed grains, consolidation of the porous sandstone and small displacements of sedimentary beds. Zones of deformation bands oriented parallel to the beds and formation contacts subdivided the overburden into thin mechanical layers that slipped over one another during doming. Measurements of outcrop-scale fault populations at the three mountains reveal a network of faults that strikes at high angles to sedimentary beds which themselves strike tangentially about the domes. These faults have normal and reverse components of slip that accommodated bending and stretching strains within the strata. An early stage of this deformation is displayed at Mount Holmes, where states of stress computed from three fault samples correlate with the theoretical distribution of stresses resulting from bending of thin, circular, elastic plates. Field observations and analysis of frictional driving stresses acting on horizontal planes above an opening-mode dislocation, as well as the paleostress analysis of faulting, indicate that bedding-plane slip and layer flexure were important components of the early deformation. As the amplitude of doming increased, radial and circumferential stretching of the strata and rotation of the older faults in the steepening limbs of the domes increased the complexity of the fault patterns. Steeply-dipping, map-scale faults with dip-slip displacements indicate a late-stage jostling of major blocks over the central

  15. The giant Shakhdara migmatitic gneiss dome, Pamir, India-Asia collision zone: 1. Geometry and kinematics

    NASA Astrophysics Data System (ADS)

    Stübner, Konstanze; Ratschbacher, Lothar; Rutte, Daniel; Stanek, Klaus; Minaev, Vladislav; Wiesinger, Maria; Gloaguen, Richard

    2013-07-01

    Cenozoic gneiss domes comprise one third of the surface exposure of the Pamir and provide a window into the deep crustal processes of the India-Asia collision. The largest of these are the doubly vergent, composite Shakhdara-Alichur domes of the southwestern Pamir, Tajikistan, and Afghanistan; they are separated by a low-strain horst. Top-to-SSE, noncoaxial pervasive flow over the up to 4 km thick South Pamir shear zone exhumed crust from 30-40 km depth in the ~250 × 80 km Shakhdara dome; the top-to-NNE Alichur shear zone exposed upper crustal rocks in the ~125 × 25 km Alichur dome. The Gunt shear zone bounds the Shakhdara dome in the north and records alternations of normal shear and dextral transpression; it contributed little to bulk exhumation. Footwall exhumation along two low-angle, normal-sense detachments resulted in up to 90 km syn-orogenic ~N-S extension. Extension in the southwestern Pamir opposes shortening in a fold-thrust belt north of the domes and in particular in the Tajik depression, where an evaporitic décollement facilitated upper crustal shortening. Gravitational collapse of the Pamir-plateau margin drove core-complex formation in the southwestern Pamir and shortening of the weak foreland adjacent to the plateau. Overall, this geometry defines a "vertical extrusion" scenario, comprising frontal and basal underthrusting and thickening, and hanging gravitationally driven normal shear. In contrast to the Himalayan vertical extrusion scenario, erosion in the Pamir was minor, preserving most of the extruded deep crust, including the top of the South Pamir shear zone at peak elevations throughout the dome.

  16. Were the world's youngest eclogites (NW D'Entrecasteaux Islands, Papua New Guinea) exhumed in rising gneiss domes or by shear on a deep-seated fault?

    NASA Astrophysics Data System (ADS)

    Little, T. A.; Hacker, B.; Seward, G.

    2008-12-01

    The up to ~2.5 km-high gneiss domes of the NW D'Entrecasteaux Islands of Papua New Guinea host the world's youngest terrane of HP (eclogite-facies, ~2-4 Ma) to UHP (coesite-bearing) gneissic rocks (~8 Ma). Previous models for their exhumation at >2 cm/yr have called upon: 1) buoyant rise of crustal diapers, or 2) normal-slip on deeply penetrating faults. A recent variant of the latter suggests that a paleo- subduction zone near the southern edge of the Solomon Sea has been inverted as a result of microplate tectonics. We present structural, microstructural, and electron back-scatter diffraction data of lattice preferred orientations (LPO's) from gneisses of Goodenough and Fergusson Islands to further explore mechanisms of exhumation. Relict eclogite-facies assemblages occur in mafic dikes and boudins, but most HP deformational fabrics are overprinted. The enclosing felsic gneisses are pervaded by amphibolite-facies ductile fabrics formed during their exhumation from the lower crust. These migmatitic rocks (metatexites) were partially molten during their deformation at temperatures of 570-730°C and pressures of 7-11 kb, but today are dominated by solid-state fabrics. The gneisses are capped by remnants of an ultramafic sheet that did not experience HP metamorphism. Below the ultramafics is a ~1 km-thick carapace zone. These high-strain gneisses generally have domal fabrics parallel to, and gradational to, those in the underlying core zone, which they locally rework. Active NE-dipping normal faults on the NE flank of the domes cut across the ultramafic contact and are underlain by a m-thick zone of pseudotachylite-bearing S/C fabrics. A sweeping pattern of stretching lineations reveals a 3-D pattern of ductile flow. In both the carapace and upper core zone, lineations are mostly EW: subparallel to the long dimension of the domes and perpendicular to plate motion in the Woodlark Rift. At greater structural depth, within the core zone, they deflect to become more

  17. Shortening and syn-contractional extension: the burial and exhumation history of the Cenozoic Central Pamir Gneiss domes, Tajikistan

    NASA Astrophysics Data System (ADS)

    Rutte, Daniel; Ratschbacher, Lothar; Schneider, Susanne; Stearns, Michael A.

    2014-05-01

    We present a structural and thermochronologic study of the Cenozoic gneiss domes and their cover in the eastern Central Pamir. Emphasis is laid on flow along the bounding shear zones, faulting in their hanging walls, and geometric analysis by balanced structural cross-sections. Cenozoic deformation related to the India-Asia collision dominates the structure of the Central Pamir. The gneiss domes form asymmetric, elongate (~80 km E-W, ~15 km N-S), en-échelon structures, exhibiting up to upper amphibolite facies metamorphic sedimentary rocks of Phanerozoic age (proven by detrital zircon studies). They are bound by E-trending normal sense shear zones with the northern boundary accommodating most of the displacement. Relics of large-scale thrust sheets and repetitions in the stratigraphic succession document the pre-extensional N-S shortening that thickened the crust. Structural studies—including fault-slip analysis—in the hanging wall of the normal sense shear zones document four major phases of ductile to brittle deformation in the Cenozoic: A first brittle-ductile phase of N-S shortening includes isoclinal folds and deforms Ordovician to Cretaceous strata. This deformation is overprinted by brittle-ductile N-S extension structures that we relate to the normal sense motion along the bounding shear zones of the domes (cooling ages constrain normal shear to ~19-14 Ma; Ar-Ar, AFT geochronology). A third phase - brittle N-S shortening - overprinted the older structures. It was followed by the latest stage, E-W dipping normal faults that we relate to rifting along the Karakul rift. These four phases of deformation can be traced throughout the region. The normal sense North Muskol Shear Zone (NMSZ) defines the northern boundary of the Muskol and Shatput domes and is among the major structures of the region. The metamorphic gradient across the NMSZ reaches from amphibolite-facies ms+bt+grt±sil±ky-schists and gneisses in the footwall to non-metamorphic to greenschist

  18. Ages and origins of rocks of the Killingworth dome, south-central Connecticut: Implications for the tectonic evolution of southern New England

    USGS Publications Warehouse

    Aleinikoff, J.N.; Wintsch, R.P.; Tollo, R.P.; Unruh, D.M.; Fanning, C.M.; Schmitz, M.D.

    2007-01-01

    The Killingworth dome of south-central Connecticut occurs at the southern end of the Bronson Hill belt. It is composed of tonalitic and trondhjemitic orthogneisses (Killingworth complex) and bimodal metavolcanic rocks (Middletown complex) that display calc-alkaline affinities. Orthogneisses of the Killingworth complex (Boulder Lake gneiss, 456 ?? 6 Ma; Pond Meadow gneiss, ???460 Ma) were emplaced at about the same time as eruption and deposition of volcanic-sedimentary rocks of the Middletown complex (Middletown Formation, 449 ?? 4 Ma; Higganum gneiss, 459 ?? 4 Ma). Hidden Lake gneiss (339 ?? 3 Ma) occurs as a pluton in the core of the Killingworth dome, and, on the basis of geochemical and isotopic data, is included in the Killingworth complex. Pb and Nd isotopic data suggest that the Pond Meadow, Boulder Lake, and Hidden Lake gneisses (Killingworth complex) resulted from mixing of Neoproterozoic Gander terrane sources (high 207Pb/204Pb and intermediate ??Nd) and less radiogenic (low 207Pb/204Pb and low ??Nd) components, whereas Middletown Formation and Higganum gneiss (Middletown complex) were derived from mixtures of Gander basement and primitive (low 207Pb/204Pb and high ??Nd) sources. The less radiogenic component for the Killingworth complex is similar in isotopic composition to material from Laurentian (Grenville) crust. However, because published paleomagnetic and paleontologic data indicate that the Gander terrane is peri-Gondwanan in origin, the isotopic signature of Killingworth complex rocks probably was derived from Gander basement that contained detritus from non-Laurentian sources such as Amazonia, Baltica, or Oaxaquia. We suggest that the Killingworth complex formed above an east-dipping subduction zone on the west margin of the Gander terrane, whereas the Middletown complex formed to the east in a back-arc rift environment. Subsequent shortening, associated with the assembly of Pangea in the Carboniferous, resulted in Gander cover terranes over the

  19. Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

    NASA Astrophysics Data System (ADS)

    Ye, Zhou; Nain, Amrinder S.; Behkam, Bahareh

    2016-06-01

    Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for

  20. Melt-spun shaped fibers with enhanced surface effects: fiber fabrication, characterization and application to woven scaffolds.

    PubMed

    Park, S J; Lee, B-K; Na, M H; Kim, D S

    2013-08-01

    Scaffolds with a high surface-area-to-volume ratio (SA:V) are advantageous with regard to the attachment and proliferation of cells in the field of tissue engineering. This paper reports on the development of novel melt-spun fibers with a high SA:V, which enhanced the surface effects of a fiber-based scaffold while maintaining its mechanical strength. The cross-section of the fibers was altered to a non-circular shape, producing a higher SA:V for a similar cross-sectional area. To obtain fibers with non-circular cross-sectional shape, or shaped fibers, three different types of metal spinnerets were fabricated for the melt-spinning process, each with circular, triangular or cruciform capillaries, using deep X-ray lithography followed by nickel electroforming. Using these spinnerets, circular and shaped fibers were manufactured with biodegradable polyester, polycaprolactone. The SA:V increase in the shaped fibers was experimentally investigated under different processing conditions. Tensile tests on the fibers and indentation tests on the woven fiber scaffolds were performed. The tested fibers and scaffolds exhibited similar mechanical characteristics, due to the similar cross-sectional area of the fibers. The degradation of the shaped fibers was notably faster than that of circular fibers, because of the enlarged surface area of the shaped fibers. The woven scaffolds composed of the shaped fibers significantly increased the proliferation of human osteosarcoma MG63 cells. This approach to increase the SA:V in shaped fibers could be useful for the fabrication of programmable, biodegradable fiber-based scaffolds in tissue engineering.

  1. Petrology and emplacement dynamics of the intrusive and extrusive rhyolites of Obsidian Dome Inyo Craters volcanic chain, eastern California

    SciTech Connect

    Vogel, T.A.; Schuraytz, B.C.; Eichelberger, J.C.; Stockman, H.W.; Westrich, H.R.; Younker, L.W.; Horkowitz, J.P.

    1989-01-01

    Drilling at Obsidian Dome has provided continuous core samples of the distal and proximal portions of Obsidian Dome, its conduit, and an associated feeder dike. Both the dome and conduit are chemically and mineralogically zoned and consist of a finely porphyritic, high-Ba, low-silica rhyolite occurring in the basal portion of the dome and margins of the conduit and a finely porphyritic, low-Ba, higher silica rhyolite in the upper portion of the dome and center of the conduit. The high-Ba rhyolite contains two distinct phenocrysts assemblages with two distinct compositions, and represents mingled magmas. The low-Ba rhyolite in the dome and conduit contains significantly fewer disequilibrium phenocrysts and is only slightly mingled. The dike, sampled at 600 m depth, as well as a related tephra fall from Obsidian Dome vent, are entirely low-Ba rhyolite that contain no evidence of magma mingling. End members of the mingled magma, calculated using two different methods, are a 63 percent silica end member, and a silicic end member identical in composition to the dike and tephra fall from Obsidian Dome vent. This silicic end member was the first magma emplaced in the dike, and comprised much or all of the first magma vented to the surface during formation of the Obsidian Dome vent when eruption rates were high. Magma mingling of mafic and rhyolite magmas occurred during formation of the conduit. 59 refs., 16 figs., 10 tabs.

  2. Dry spun 3D woven carbon nanotube anode electrode for Li-lon batteries.

    PubMed

    Ryu, Seongwoo; Kim, Yunkyoung; Lee, Haeshin; Hong, Soon Hyung

    2014-12-01

    Although carbon nanotubes (CNTs) have extraordinary mechanical, thermal, and electrical properties, application of CNTs remains limited due to their unique nano-sized tubular forms. CNT electrodes have relatively high sheet resistance, which does not meet the industrial requirements of various electrode materials. Thus, there are still challenges for improving the performance of CNTs in real applications, particularly in terms of satisfying industrial requirements. In this study, to utilize CNTs in bulk scale electrode applications, we developed a dry spinning technique. The dry spinning technique is a solid state fiber spinning technique that provides an adjustable aligned structure. The dry spinning approach also offers a facile and inexpensive fabrication process, factors which are favorable for industrial scalability for fabricating electrodes. We demonstrate a multilayer stacking process for enhancing the performance for Li-ion batteries. Multi-layer CNT textiles have low sheet resistance and a 3D woven structure provides high surface area. The fabricated 3D woven structured electrode delivers a higher reversible capacity of more than 400 mA hr/g with high cycle stabilities.

  3. Core-spun carbon nanotube yarn supercapacitors for wearable electronic textiles.

    PubMed

    Zhang, Daohong; Miao, Menghe; Niu, Haitao; Wei, Zhixiang

    2014-05-27

    Linear (fiber or yarn) supercapacitors have demonstrated remarkable cyclic electrochemical performance as power source for wearable electronic textiles. The challenges are, first, to scale up the linear supercapacitors to a length that is suitable for textile manufacturing while their electrochemical performance is maintained or preferably further improved and, second, to develop practical, continuous production technology for these linear supercapacitors. Here, we present a core/sheath structured carbon nanotube yarn architecture and a method for one-step continuous spinning of the core/sheath yarn that can be made into long linear supercapacitors. In the core/sheath structured yarn, the carbon nanotubes form a thin surface layer around a highly conductive metal filament core, which serves as current collector so that charges produced on the active materials along the length of the supercapacitor are transported efficiently, resulting in significant improvement in electrochemical performance and scale up of the supercapacitor length. The long, strong, and flexible threadlike supercapacitor is suitable for production of large-size fabrics for wearable electronic applications.

  4. Alteration minerals on the Santiaguito lava dome complex, Santa María volcano, Guatemala

    NASA Astrophysics Data System (ADS)

    Ball, J. L.; Calder, E. S.; Giese, R.

    2010-12-01

    Santiaguito is a relatively young complex of four lava domes located at the foot of the Santa María volcano in Guatemala. The domes have been erupting intermittently since 1922, and have shown various degrees of hydrothermal activity throughout their development. Hydrothermal systems in older volcanic edifices (Casita in Nicaragua, La Soufriere of Guadeloupe) are known to weaken rock and promote collapses, but their effects and development in young lava domes is less well constrained. Santiaguito has experienced several relatively small dome collapses (≦ 3 million m3) in the past, but it is unclear what role hydrothermal processes have played in these collapses. Currently, low-temperature active fumaroles are present on the domes, indicating the presence of a hydrothermal system. Samples of unconsolidated ash and sediment and rock chips were collected from the interior of fumaroles on the El Brujo lava dome to determine if hydrothermal alteration minerals were present. X-ray diffraction (XRD) was used to identify the presence of clay minerals in the powdered samples. Additional semi-quantitative identification was obtained using backscattered electron images (BSE) collected with a scanning electron microscope (SEM). Both analyses were performed at the University at Buffalo. Preliminary XRD analyses were unable to conclusively detect alteration minerals in powdered samples; however, BSE images of the same samples appeared to show alteration minerals (montmorillonite, saponite) adhering to individual ash grains. Further SEM analyses are being conducted on thin sections of the rock chips to determine if alteration minerals are present in dome rock as well as in the unconsolidated material. Development of alteration minerals on the relatively young (~50-90 year old) Santiaguito lava domes may indicate an increased risk for alteration-driven instabilities and collapses. Altered volcanic rocks are less competent, have lower shear strength and are more susceptible to

  5. New approaches to inferences for steep-sided domes on Venus

    NASA Astrophysics Data System (ADS)

    Quick, Lynnae C.; Glaze, Lori S.; Baloga, Stephen M.; Stofan, Ellen R.

    2016-06-01

    New mathematical approaches for the relaxation and emplacement of viscous lava domes are presented and applied to steep-sided domes on Venus. A similarity solution approach is applied to the governing equation for fluid flow in a cylindrical geometry for two distinct scenarios. In the first scenario, dome relaxation is explored assuming a constant volume of fluid (i.e. lava) has been rapidly emplaced onto the surface. Cooling of lava is represented by a time-variable viscosity and singularities inherent in previous models for dome relaxation have been eliminated. At the onset of relaxation, bulk dynamic viscosities lie in the range between 1010-1016 Pa s, consistent with basaltic-andesite to rhyolitic compositions. Plausible relaxation times range from 5 to 5000 years, depending on initial lava viscosity. The first scenario, however, is only valid during the final stages of dome relaxation and does not consider the time taken for lava to be extruded onto the surface. In the second scenario, emplacement and growth of a steep-sided dome is considered when the volume of lava on the surface increases over time (i.e. time-variable volume approach). The volumetric flowrate may depend on an arbitrary power of the dome thickness, thus embracing Newtonian as well as other rheologies for describing terrestrial and planetary mass flows. The approach can be used to distinguish between basic flowrate models for fluid emplacement. The formalism results in radial expansion of a dome proportional to t1/2, consistent with the diffusive nature of the governing equation. The flow at the front is shown to thicken as the front advances for a constant rate of lava supply. Emplacement times are intimately correlated with the bulk rheology. Comparison of the theoretical profiles with the shape of a typical dome on Venus indicates that a Newtonian bulk rheology is most appropriate, consistent with prior studies. However, results here suggest a bulk dynamic viscosity of 1012-1013 Pa s and

  6. Partial melting of the South Qinling orogenic crust, China: Evidence from Triassic migmatites and diorites of the Foping dome

    NASA Astrophysics Data System (ADS)

    Zhang, He; Ye, Ri-Sheng; Liu, Bing-Xiang; Wang, Yan; Zhang, Yuan-Shuo; Siebel, Wolfgang; Chen, Fukun

    2016-09-01

    The Qinling orogen was ultimately formed by suturing of the South Qinling and Yangtze blocks, but the exact timing of the final amalgamation of the two blocks has not been well established so far. Partial melting of the Qinling orogenic continental crust resulted in the generation of migmatites, and such rocks may help to decipher the chronology of such event. In this paper, we report U-Pb ages, trace element, and Hf isotopic compositions of zircons from migmatites and diorite gneisses of the Foping dome, South Qinling. Zircons from migmatites form anhedral grains of variable sizes that are characterized by complex trace element compositions. Based on zircon U-Pb ages, the migmatites can be subdivided into two groups: Group 1 migmatites mainly retain Triassic zircons with U-Pb ages of 214-211 Ma and Hf model ages of 1.46 Ga in core and rim domains; zircons from Group 2 migmatites record both Triassic ( 210 Ma) and Neoproterozoic U-Pb ages, analogous to igneous rocks of the Wudang and Yaolinghe Groups exposed in South Qinling. Zircons from the diorite gneisses yield U-Pb ages of 216-210 Ma with Hf isotopic composition (TDM2 ages of 1.46 Ga) similar to the migmatites. Evidence from whole-rock Nd isotopic analyses also points to a similar genesis between migmatites and diorite gneisses. It is proposed that Group 1 migmatites were derived by melting of Triassic diorites, while Group 2 migmatites were derived from Neoproterozoic igneous rocks, a major basement lithology of South Qinling. Partial melting of the orogenic crust took place at 214-210 Ma, approximately consistent with the retrograde metamorphism of granulites exposed along the suture zone between the South Qinling and Yangtze blocks. We suggest that the collision of these two blocks occurred prior to 215 Ma and that the Foping dome resulted from rapid collapse of an overthickened crust followed by partial melting enhanced by asthenospheric influx.

  7. 3-DIMENSIONAL Geometric Survey and Structural Modelling of the Dome of Pisa Cathedral

    NASA Astrophysics Data System (ADS)

    Aita, D.; Barsotti, R.; Bennati, S.; Caroti, G.; Piemonte, A.

    2017-02-01

    This paper aims to illustrate the preliminary results of a research project on the dome of Pisa Cathedral (Italy). The final objective of the present research is to achieve a deep understanding of the structural behaviour of the dome, through a detailed knowledge of its geometry and constituent materials, and by taking into account historical and architectural aspects as well. A reliable survey of the dome is the essential starting point for any further investigation and adequate structural modelling. Examination of the status quo on the surveys of the Cathedral dome shows that a detailed survey suitable for structural analysis is in fact lacking. For this reason, high-density and high-precision surveys have been planned, by considering that a different survey output is needed, according both to the type of structural model chosen and purposes to be achieved. Thus, both range-based (laser scanning) and image-based (3D Photogrammetry) survey methodologies have been used. This contribution introduces the first results concerning the shape of the dome derived from surveys. Furthermore, a comparison is made between such survey outputs and those available in the literature.

  8. Siple Dome Ice Cores: Implications for West Antarctic Climate and ENSO Events

    NASA Astrophysics Data System (ADS)

    Jones, T.; White, J. W.

    2010-12-01

    Ice cores at Siple Dome, West Antarctic receive the majority of their precipitation from Pacific Ocean moisture sources. Pacific climate patterns, particularly the El Niño-Southern Oscillation, affect the local temperature, atmospheric circulation, and snow accumulation at Siple Dome, as well as isotopic signals (∂D and ∂18O). We examined isotopes, accumulation and borehole temperatures from a number of shallow ice cores distributed 60km across the Dome. The data reveal a strong microclimate heavily influenced by South Pacific climate and the location of the Amundsen Sea Low Pressure Area. The Dome Summit and Pacific Flank respond to La Niña conditions by warming, increasing isotope ratios and increased snowfall. The Inland Flank responds to El Niño conditions and cold interior air masses by cooling, decreasing isotope ratios and decreased snowfall. Spectral analysis of the ∂D record shows a distinct shift in ocean-atmosphere climate dynamics in the late 19th century, where scattered bi-decadal to decadal periodicities change to include more intensely grouped and decreasing periodicities as low as two years at the end of the 20th century. Similar changes are seen in South Pacific coral isotope records. Map of Siple Dome including local grid locations for the seven shallow cores B-H. Note the Pacific Ocean and Inland (South Pole) oriented cores. [Modified after Bertler et al., 2006].

  9. Improved manufacturing techniques for RF and laser hardening of missile domes. Phase I. Technical report

    SciTech Connect

    Pawlewicz, W.T.; Mann, I.B.; Martin, P.M.; Hays, D.D.; Graybeal, A.G.

    1982-07-01

    This report summarizes key results and accomplishements during the first year of a Manufacturing Methods and Technology project to adapt an existing Pacific Northwest Laboratory (PNL) optical coating capability developed for high-power fusion-laser applications to the case of rf and laser hardening of plastic missile domes used by the US Army (MICOM). The primary objective of the first year's work was to demonstrate rf hardening of Hellfire and Copperhead 1.06-micron missile domes by use of transparent conductive Indium Tin Oxide (ITO) coatings. The project thus involved adaptation of a coating material and process developed for flat glass components used in fusion lasers to the case of hemispherical or conical heat-sensitive plastic domes used on laser-guided missiles. Specific ITO coating property goals were an electrical sheet resistance of 10 Ohms/square, a coated-dome transmission of 80% or more at 1.06 micron wavelength (compared to 90% for a bare dome), and good adhesion. The sheet resistance goal of 10 Ohms/square was expected to result in an rf attenuation of 30 dB at the frequencies of importance.

  10. Sea-ice-related halogen enrichment at Law Dome, coastal East Antarctica

    NASA Astrophysics Data System (ADS)

    Vallelonga, Paul; Maffezzoli, Niccolo; Moy, Andrew D.; Curran, Mark A. J.; Vance, Tessa R.; Edwards, Ross; Hughes, Gwyn; Barker, Emily; Spreen, Gunnar; Saiz-Lopez, Alfonso; Corella, J. Pablo; Cuevas, Carlos A.; Spolaor, Andrea

    2017-02-01

    The Law Dome site is ideal for the evaluation of sea ice proxies due to its location near to the Antarctic coast, regular and high accumulation throughout the year, an absence of surface melting or remobilization, and minimal multiyear sea ice. We present records of bromine and iodine concentrations and their enrichment beyond seawater compositions and compare these to satellite observations of first-year sea ice area in the 90-130° E sector of the Wilkes coast. Our findings support the results of previous studies of sea ice variability from Law Dome, indicating that Wilkes coast sea ice area is currently at its lowest level since the start of the 20th century. From the Law Dome DSS1213 firn core, 26 years of monthly deposition data indicate that the period of peak bromine enrichment is during austral spring-summer, from November to February. Results from a traverse along the lee (western) side of Law Dome show low levels of sodium and bromine deposition, with the greatest fluxes in the vicinity of the Law Dome summit. Finally, multidecadal variability in iodine enrichment appears well correlated to bromine enrichment, suggesting a common source of variability that may be related to the Interdecadal Pacific Oscillation (IPO).

  11. Crocodile-inspired dome-shaped pressure receptors for passive hydrodynamic sensing.

    PubMed

    Kanhere, Elgar; Wang, Nan; Kottapalli, Ajay Giri Prakash; Asadnia, Mohsen; Subramaniam, Vignesh; Miao, Jianmin; Triantafyllou, Michael

    2016-08-22

    Passive mechanosensing is an energy-efficient and effective recourse for autonomous underwater vehicles (AUVs) for perceiving their surroundings. The passive sensory organs of aquatic animals have provided inspiration to biomimetic researchers for developing underwater passive sensing systems for AUVs. This work is inspired by the 'integumentary sensory organs' (ISOs) which are dispersed on the skin of crocodiles and are equipped with slowly adapting (SA) and rapidly adapting (RA) receptors. ISOs assist crocodiles in locating the origin of a disturbance, both on the water surface and under water, thereby enabling them to hunt prey even in a dark environment and turbid waters. In this study, we construct SA dome receptors embedded with microelectromechanical systems (MEMS) piezoresistive sensors to measure the steady-state pressures imparted by flows and RA dome receptors embedded with MEMS piezoelectric sensors to detect oscillatory pressures in water. Experimental results manifest the ability of SA and RA dome receptors to sense the direction of steady-state flows and oscillatory disturbances, respectively. As a proof of concept, the SA domes are tested on the hull of a kayak under various pressure variations owing to different types of movements of the hull. Our results indicate that the dome receptors are capable of discerning the angle of attack and speed of the flow.

  12. Degradation of Dome Cutting Minerals in Hanford Waste - 13100

    SciTech Connect

    Reynolds, Jacob G.; Cooke, Gary A.; Huber, Heinz J.

    2013-07-01

    At the Hanford Tank Farms, recent changes in retrieval technology require cutting new risers in several single-shell tanks. The Hanford Tank Farm Operator is using water jet technology with abrasive silicate minerals such as garnet or olivine to cut through the concrete and rebar dome. The abrasiveness of these minerals, which become part of the high-level waste stream, may enhance the erosion of waste processing equipment. However, garnet and olivine are not thermodynamically stable in Hanford waste, slowly degrading over time. How likely these materials are to dissolve completely in the waste before the waste is processed in the Waste Treatment and Immobilization Plant can be evaluated using theoretical analysis for olivine and collected direct experimental evidence for garnet. Based on an extensive literature study, a large number of primary silicates decompose into sodalite and cancrinite when exposed to Hanford waste. Given sufficient time, the sodalite also degrades into cancrinite. Even though cancrinite has not been directly added to any Hanford tanks during process times, it is the most common silicate observed in current Hanford waste. By analogy, olivine and garnet are expected to ultimately also decompose into cancrinite. Garnet used in a concrete cutting demonstration was immersed in a simulated supernate representing the estimated composition of the liquid retrieving waste from Hanford tank 241-C-107 at both ambient and elevated temperatures. This simulant was amended with extra NaOH to determine if adding caustic would help enhance the degradation rate of garnet. The results showed that the garnet degradation rate was highest at the highest NaOH concentration and temperature. At the end of 12 weeks, however, the garnet grains were mostly intact, even when immersed in 2 molar NaOH at 80 deg. C. Cancrinite was identified as the degradation product on the surface of the garnet grains. In the case of olivine, the rate of degradation in the high

  13. Degradation of dome cutting minerals in Hanford waste

    SciTech Connect

    Reynolds, Jacob G.; Huber, Heinz J.; Cooke, Gary A.

    2013-01-11

    At the Hanford Tank Farms, recent changes in retrieval technology require cutting new risers in several single-shell tanks. The Hanford Tank Farm Operator is using water jet technology with abrasive silicate minerals such as garnet or olivine to cut through the concrete and rebar dome. The abrasiveness of these minerals, which become part of the high-level waste stream, may enhance the erosion of waste processing equipment. However, garnet and olivine are not thermodynamically stable in Hanford waste, slowly degrading over time. How likely these materials are to dissolve completely in the waste before the waste is processed in the Waste Treatment and Immobilization Plant can be evaluated using theoretical analysis for olivine and collected direct experimental evidence for garnet. Based on an extensive literature study, a large number of primary silicates decompose into sodalite and cancrinite when exposed to Hanford waste. Given sufficient time, the sodalite also degrades into cancrinite. Even though cancrinite has not been directly added to any Hanford tanks during process times, it is the most common silicate observed in current Hanford w