WorldWideScience

Sample records for ruthenium-containing sheet composites

  1. Diffusion aluminide coatings for internal surface of rhenium- and rhenium-ruthenium-containing single-crystal superalloys turbine blades: Part I

    Science.gov (United States)

    Mubovadzhyan, S. A.; Galoyan, A. G.

    2012-09-01

    Process of formation rhenium or refractory carbides based diffusion barrier layer (coating) on internal surface of rhenium- and rhenium-ruthenium-containing single-crystal high-temperature alloys (superalloy) turbine blades, prior to diffusion aluminide coating deposition, is studied. It is shown that diffusion barrier layer is preventing deleterious secondary reaction zone formation under aluminide coating during long-term high-temperature operation. The kinetics of powder carburizing process of rhenium- and rhenium-ruthenium-containing high-temperature alloys is investigated, and conditions for carburizing these alloys are determined. The phase composition of the surface layer after carburizing is studied, and the effect of the fractional composition of a carbon-based powder mixture on the carburizing rate is determined.

  2. Formation of Saddle-Shaped Composite Sheets

    Science.gov (United States)

    Verdinsh, G.; Rocens, K.; Serdyuk, D.

    2000-11-01

    Based on the deformation model of an unbalanced multilayer composite, changes in bending curvatures of sheet-type composites with nonsymmetric structure relative to the midplane of the sheet, depending on the moisture of layers, are predicted. The bending curvatures of saddle-shaped sheets of wood-based composites are calculated with regard to the physical and mechanical properties, geometrical dimensions, orientation, and distribution of layers. The analytical results are compared with the bending curvatures found experimentally for a four-layered unbalanced composite made of birch veneer. The applied calculation model enables us to determine the values of bending curvatures of saddle-shaped wood composite sheets, which can be used in elaborating the technological recommendations.

  3. Reflective composite sheet design for LCD backlight recycling.

    Science.gov (United States)

    Kim, Taehyung; Kim, Kibeom; Lee, Eun Soo; Jeong, Won Young; Lim, Dae Young; Choi, Suk-Won

    2014-05-01

    We have designed a reflective composite sheet consisting of a birefringent polymer matrix and isolated isotropic or minimally birefringent fibers. The optical properties of the sheet have been investigated in terms of the width, spacing, and thickness of the individual fibers. Commercial software (FDTD Solution) was used to simulate the reflectance of the proposed sheet, and conventional processes such as cast-film extrusion in combination with solid-state drawing were used to manufacture the multilayer composite sheet. The measured and simulated reflectance spectra confirm the feasibility of employing the sheet as a reflective polarizer.

  4. Mechanical and electrical properties of polycarbonate nanotube buckypaper composite sheets

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Giang T; Park, Young-Bin; Wang Shiren; Liang Zhiyong; Wang Ben; Zhang, Chuck [High-Performance Materials Institute (HPMI), Department of Industrial and Manufacturing Engineering, Florida A and M University, Florida State University College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Funchess, Percy; Kramer, Leslie [Lockheed Martin Missiles and Fire Control-Orlando, Orlando, FL 32819-8907 (United States)], E-mail: gte640q@yahoo.com

    2008-08-13

    The thermogravimetric, mechanical, and electrical properties of composite sheets produced by infiltrating single-wall carbon nanotube films (also known as 'buckypapers') with polycarbonate solution were characterized. The composite sheets showed improved stiffness and toughness, while the electrical conductivity decreased, as compared to a neat buckypaper. In addition, polycarbonate/buckypaper composite sheets showed higher resistance to handling and processing damages. Experimental results suggest the viability of the infiltration process as a means to toughen buckypapers and to fabricate polymer/carbon nanotube composites having high nanotube concentration and controlled nanotube structure.

  5. Laser Spectroscopy of Ruthenium Containing Diatomic Molecules: RuH/D and RuP.

    Science.gov (United States)

    Adam, Allan G.; Konder, Ricarda M.; Nickerson, Nicole M.; Linton, Colan; Tokaryk, D. W.

    2015-06-01

    In the last few years, the Cheung group in Hong Kong and the Steimle group in Arizona have successfully studied several ruthenium containing diatomic molecules, RuX (X =C, O, N, B, using the laser-ablation molecular jet technique. Based on this success, the UNB spectroscopy group decided to try and find the optical signatures of other RuX molecules. Using CH_3OH and PH_3 as reactant gases, the RuH and RuP diatomic molecules have been detected in surveys of the 420 - 675 nm spectral region. RuD has also been made using fully deuterated methanol as a reactant. Dispersed fluorescence experiments have been performed to determine ground state vibrational frequencies and the presence of any low-lying electronic states. Rotationally resolved spectra for these molecules have also been taken and the analysis is proceeding. The most recent results will be presented. F. Wang et al., Journal of Chemical Physics 139, 174318 (2013). N. Wang et al., Journal of Physical Chemistry A 117, 13279 (2013). T. Steimle et al., Journal of Chemical Physics 119, 12965 (2003). N. Wang et al., Chemical Physics Letters 547, 21 (2012).

  6. Biomass Compositional Analysis Laboratory (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2014-07-01

    At the Biomass Compositional Analysis Laboratory, NREL scientists have more than 20 years of experience supporting the biomass conversion industry. They develop, refine, and validate analytical methods to determine the chemical composition of biomass samples before, during, and after conversion processing. These high-quality compositional analysis data are used to determine feedstock compositions as well as mass balances and product yields from conversion processes.

  7. Multifunctional smart composites with integrated carbon nanotube yarn and sheet

    Science.gov (United States)

    Chauhan, Devika; Hou, Guangfeng; Ng, Vianessa; Chaudhary, Sumeet; Paine, Michael; Moinuddin, Khwaja; Rabiee, Massoud; Cahay, Marc; Lalley, Nicholas; Shanov, Vesselin; Mast, David; Liu, Yijun; Yin, Zhangzhang; Song, Yi; Schulz, Mark

    2017-04-01

    Multifunctional smart composites (MSCs) are materials that combine the good electrical and thermal conductivity, high tensile and shear strength, good impact toughness, and high stiffness properties of metals; the light weight and corrosion resistance properties of composites; and the sensing or actuation properties of smart materials. The basic concept for MSCs was first conceived by Daniel Inman and others about 25 years ago. Current laminated carbon and glass fiber polymeric composite materials have high tensile strength and are light in weight, but they still lack good electrical and thermal conductivity, and they are sensitive to delamination. Carbon nanotube yarn and sheets are lightweight, electrically and thermally conductive materials that can be integrated into laminated composite materials to form MSCs. This paper describes the manufacturing of high quality carbon nanotube yarn and sheet used to form MSCs, and integrating the nanotube yarn and sheet into composites at low volume fractions. Various up and coming technical applications of MSCs are discussed including composite toughening for impact and delamination resistance; structural health monitoring; and structural power conduction. The global carbon nanotube overall market size is estimated to grow from 2 Billion in 2015 to 5 Billion by 2020 at a CAGR of 20%. Nanotube yarn and sheet products are predicted to be used in aircraft, wind machines, automobiles, electric machines, textiles, acoustic attenuators, light absorption, electrical wire, sporting equipment, tires, athletic apparel, thermoelectric devices, biomedical devices, lightweight transformers, and electromagnets. In the future, due to the high maximum current density of nanotube conductors, nanotube electromagnetic devices may also become competitive with traditional smart materials in terms of power density.

  8. Woven Glass Fiber Composites with Aligned Carbon Nanotube Sheet Interlayers

    Directory of Open Access Journals (Sweden)

    Hardik Bhanushali

    2016-01-01

    Full Text Available This investigation describes the design, fabrication, and testing of woven glass fiber reinforced epoxy matrix laminates with aligned CNT sheets integrated between plies in order to improve the matrix dominated through thickness properties such as the interlaminar fracture toughness at ply interfaces. Using aligned CNT sheets allows for a concentration of millimeter long CNTs at the most likely point of laminate failure. Mode I and Mode II interlaminar fracture toughness of various CNT modified samples were investigated using double cantilever beam (DCB and end notched flexure (ENF experiments, respectively. Short beam strength (SBS and in-plane tensile properties of the CNT modified samples were also investigated. Moderate improvement was observed in Mode I and Mode II fracture toughness at crack initiation when aligned CNT sheets with a basis weight of 0.354 g/m2 were used to modify the ply interface. No compromise in the in-plane mechanical properties of the laminate was observed and very little improvement was observed in the shear related short beam strength of the CNT modified laminates as compared to the control samples. Integration of aligned CNT sheets into the composite laminate imparted in-plane and through thickness electrical properties into the nonconductive glass fiber reinforced epoxy composite laminates.

  9. Preparation of Sheet-like Polymer-Encapsulated Composite Particles by Seeded Polymerization from Sub-micrometer Sheets.

    Science.gov (United States)

    Huang, Ting; Yao, Kuncheng; Wu, Teng; Qiu, Dong

    2015-07-01

    Seeded polymerization has been widely used to fabricate polymer-encapsulated inorganic particles (IPs). The most frequently used seeds are spherical, whereas nonspherical particles are not well documented. Recently, sheet-like IPs have attracted much attention in the context of polymer composites. This article is therefore dedicated to understanding seeded polymerization from submicron sheets and focuses on the control of the overall morphology of the composite particles obtained. However, it was found that the composite particles only maintained the sheet-like morphology of the seeds at a low polymer content, whereas they became hamburger-like at a high polymer content owing to minimization of the interfacial energy. Interestingly, when cross-linked, the sheet-like morphology could be well preserved, even at a rather high polymer content. With the encapsulating polymer layer, the obtained sheet-like composite particles showed improved compatibility with the polymer matrix and could be well dispersed in polymer matrix when simply blended.

  10. Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

    National Research Council Canada - National Science Library

    Qun Xiang; Shuji Fukahori; Naoyuki Yamashita; Hiroaki Tanaka; Taku Fujiwara

    2017-01-01

    .... In this research, a paper-like composite sheet consisting of titanium dioxide (TiO2) and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate was studied using the TiO2/zeolite composite sheet...

  11. High-pressure catalytic chemical vapor deposition of ferromagnetic ruthenium-containing carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Khavrus, Vyacheslav O., E-mail: V.Khavrus@ifw-dresden.de; Ibrahim, E. M. M.; Bachmatiuk, Alicja; Ruemmeli, Mark H.; Wolter, A. U. B.; Hampel, Silke; Leonhardt, Albrecht [IFW Dresden (Germany)

    2012-06-15

    We report on the high-pressure catalytic chemical vapor deposition (CCVD) of ruthenium nanoparticles (NPs) and single-walled carbon nanotubes (SWCNTs) by means of gas-phase decomposition of acetonitrile and ruthenocene in a tubular quartz flow reactor at 950 Degree-Sign C and at elevated pressures (between 2 and 8 bar). The deposited material consists of Ru metal cores with sizes ranging between 1 and 3 nm surrounded by a carbon matrix. The high-pressure CCVD seems to be an effective route to obtain composite materials containing metallic NPs, Ru in this work, inside a nanostructured carbon matrix protecting them from oxidation in ambient air. We find that in contradiction to the weak paramagnetic properties characterizing bulk ruthenium, the synthesized samples are ferromagnetic as predicted for nanosized particles of nonmagnetic materials. At low pressure, the very small ruthenium catalyst particles are able to catalyze growth of SWCNTs. Their yield decreases with increasing reaction pressure. Transmission electron microscopy, selected area energy-dispersive X-ray analysis, Raman spectroscopy, and magnetic measurements were used to analyze and confirm properties of the synthesized NPs and nanotubes. A discussion on the growth mechanism of the Ru-containing nanostructures is presented.

  12. Stable microbial community composition on the Greenland Ice Sheet

    Directory of Open Access Journals (Sweden)

    Michaela eMusilova

    2015-03-01

    Full Text Available The first molecular-based studies of microbes in snow and on glaciers have only recently been performed on the vast Greenland Ice Sheet (GrIS. Aeolian microbial seeding is hypothesized to impact on glacier surface community compositions. Localized melting of glacier debris (cryoconite into the surface ice forms cryoconite holes, which are considered ‘hot spots’ for microbial activity on glaciers. To date, few studies have attempted to assess the origin and evolution of cryoconite and cryoconite hole communities throughout a melt season. In this study, a range of experimental approaches was used for the first time to study the inputs, temporal and structural transformations of GrIS microbial communities over the course of a whole ablation season. Small amounts of aeolian (wind and snow microbes were potentially seeding the stable communities that were already present on the glacier (composed mainly of Proteobacteria, Cyanobacteria and Actinobacteria. However, the dominant bacterial taxa in the aeolian samples (Firmicutes did not establish themselves in local glacier surface communities. Cryoconite and cryoconite hole community composition remained stable throughout the ablation season following the fast community turnover, which accompanied the initial snow melt. The presence of stable communities in cryoconite and cryoconite holes on the GrIS will allow future studies to assess glacier surface microbial diversity at individual study sites from sampling intervals of short duration only. Aeolian inputs also had significantly different organic δ13C values (-28.0 to -27.0‰ from the glacier surface values (-25.7 to -23.6‰, indicating that in situ microbial processes are important in fixing new organic matter and transforming aeolian organic carbon. The continuous productivity of stable communities over one melt season makes them important contributors to biogeochemical nutrient cycling on glaciers.

  13. Stable microbial community composition on the Greenland Ice Sheet.

    Science.gov (United States)

    Musilova, Michaela; Tranter, Martyn; Bennett, Sarah A; Wadham, Jemma; Anesio, Alexandre M

    2015-01-01

    The first molecular-based studies of microbes in snow and on glaciers have only recently been performed on the vast Greenland Ice Sheet (GrIS). Aeolian microbial seeding is hypothesized to impact on glacier surface community compositions. Localized melting of glacier debris (cryoconite) into the surface ice forms cryoconite holes, which are considered 'hot spots' for microbial activity on glaciers. To date, few studies have attempted to assess the origin and evolution of cryoconite and cryoconite hole communities throughout a melt season. In this study, a range of experimental approaches was used for the first time to study the inputs, temporal and structural transformations of GrIS microbial communities over the course of a whole ablation season. Small amounts of aeolian (wind and snow) microbes were potentially seeding the stable communities that were already present on the glacier (composed mainly of Proteobacteria, Cyanobacteria, and Actinobacteria). However, the dominant bacterial taxa in the aeolian samples (Firmicutes) did not establish themselves in local glacier surface communities. Cryoconite and cryoconite hole community composition remained stable throughout the ablation season following the fast community turnover, which accompanied the initial snow melt. The presence of stable communities in cryoconite and cryoconite holes on the GrIS will allow future studies to assess glacier surface microbial diversity at individual study sites from sampling intervals of short duration only. Aeolian inputs also had significantly different organic δ(13)C values (-28.0 to -27.0‰) from the glacier surface values (-25.7 to -23.6‰), indicating that in situ microbial processes are important in fixing new organic matter and transforming aeolian organic carbon. The continuous productivity of stable communities over one melt season makes them important contributors to biogeochemical nutrient cycling on glaciers.

  14. Preparation and In Vitro Behavior of a Poly(lactic acid-Fiber/Hydroxyapatite Composite Sheet

    Directory of Open Access Journals (Sweden)

    Yasuhiro Tanimoto

    2009-01-01

    Full Text Available This paper describes the processing and in vitro behavior of a poly(lactic acid (PLA-fiber/hydroxyapatite (HA composite sheet consisting of a knitted PLA-fiber sheet and HA powder for bone tissue engineering. Type I collagen was used as a binding agent to combine the PLA fibers and the HA powder. Precipitate formation in Hanks' balanced salt (HBS solution was monitored to evaluate the in vitro apatite formation ability of the PLA-fiber/HA composite sheet. Precipitate formation was observed on the surface of the PLA-fiber/HA composite sheet after immersion in HBS solution for only 1 day, while no precipitate formation was observed on the PLA-fiber sheet without HA as a control. In conclusion, a PLA-fiber/HA composite sheet for use as a scaffold was successfully prepared. Within the limitations of this investigation, we confirmed that the PLA-fiber/HA composite sheet has a high apatite formation activity compared with the PLA-fiber sheet and represents a promising material for use as a scaffold.

  15. A study of the formation and dynamics of the Earth's plasma sheet using ion composition data

    Science.gov (United States)

    Lennartsson, O. W.

    1994-01-01

    Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.

  16. FEM Simulation of Bending Formability for Laminate Steel/Resin/Steel Lightweight Composite Sheet

    Institute of Scientific and Technical Information of China (English)

    Guancheng Ll; Yonglin KANG

    2003-01-01

    The ANSYS simulation software was used to analyze the bending formability of laminate steel/resin/steel lightweight composite sheet. The skin steel at external side produces relative slipping-off change during the bending due to its composite structure. The internal stress strain states, materials effect tools parameters and intermediate layer resin of lightweight sheet on slipping-off change were analyzed. The spring back and shear stress state after bending have also been discussed.

  17. Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

    OpenAIRE

    Qun Xiang; Shuji Fukahori; Naoyuki Yamashita; Hiroaki Tanaka; Taku Fujiwara

    2017-01-01

    Reverse osmosis (RO) concentrate from wastewater reuse facilities contains concentrated emerging pollutants, such as pharmaceuticals. In this research, a paper-like composite sheet consisting of titanium dioxide (TiO2) and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate was studied using the TiO2/zeolite composite sheet. The RO concentrate was obtained from a pilot-scale municipal secondary effluent reclamation plant. Effective immobilization of t...

  18. Removal of Crotamiton from Reverse Osmosis Concentrate by a TiO2/Zeolite Composite Sheet

    Directory of Open Access Journals (Sweden)

    Qun Xiang

    2017-07-01

    Full Text Available Reverse osmosis (RO concentrate from wastewater reuse facilities contains concentrated emerging pollutants, such as pharmaceuticals. In this research, a paper-like composite sheet consisting of titanium dioxide (TiO2 and zeolite was synthesized, and removal of the antipruritic agent crotamiton from RO concentrate was studied using the TiO2/zeolite composite sheet. The RO concentrate was obtained from a pilot-scale municipal secondary effluent reclamation plant. Effective immobilization of the two powders in the sheet made it easy to handle and to separate the photocatalyst and adsorbent from purified water. The TiO2/zeolite composite sheet showed excellent performance for crotamiton adsorption without obvious inhibition by other components in the RO concentrate. With ultraviolet irradiation, crotamiton was simultaneously removed through adsorption and photocatalysis. The photocatalytic decomposition of crotamiton in the RO concentrate was significantly inhibited by the water matrix at high initial crotamiton concentrations, whereas rapid decomposition was achieved at low initial crotamiton concentrations. The major degradation intermediates were also adsorbed by the composite sheet. This result provides a promising method of mitigating secondary pollution caused by the harmful intermediates produced during advanced oxidation processes. The cyclic use of the HSZ-385/P25 composite sheet indicated the feasibility of continuously removing crotamiton from RO concentrate.

  19. Improved Electromagnetic Shielding Performance of Lightweight Compression Molded Polypyrrole/Ferrite Composite Sheets

    Science.gov (United States)

    Varshney, Swati; Dhawan, S. K.

    2017-01-01

    An attempt has been made to design lightweight polypyrrole/carbon fibers and polypyrrole/carbon fibers/ferrofluid (Fe3O4 particles) composite sheets using novolac resin via compression molding for electromagnetic shielding applications. The optimized formulation has been achieved to get an excellent combination of thermal, mechanical, and electrical properties of the composite sheet. Structural and morphological studies were carried out by x-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Polypyrrole/carbon fibers composite sheets shows maximum flexural strength and a flexural modulus of 62.4 ± 1 MPa and 0.60 ± 0.02 GPa, respectively, with total shielding effectiveness of 22.8 dB in the Ku-band (12.4-18 GHz) but when ferrofluid is added to the polypyrrole/carbon fibers composite system, flexural strength increases to 92.3 ± 1 MPa and the same trend has been observed for flexural modulus with a value of 0.65 ± 0.04 GPa. This multiphase lightweight polypyrrole composite sheet having 34 vol.% of carbon fibers and 4 vol.% of Fe3O4 nanoparticles offers total shielding effectiveness of 31.9 dB (>99.99% attenuation) in the Ku-band (12.4-18 GHz) frequency range with a thickness of ˜1.25 mm. This is accredited to high dielectric losses and magnetic losses in conducting composite sheets. The observed results suggest that lightweight compression molded polypyrrole composite sheets could be a potential commercial alternative for electromagnetic shielding applications.

  20. Improved Electromagnetic Shielding Performance of Lightweight Compression Molded Polypyrrole/Ferrite Composite Sheets

    Science.gov (United States)

    Varshney, Swati; Dhawan, S. K.

    2017-03-01

    An attempt has been made to design lightweight polypyrrole/carbon fibers and polypyrrole/carbon fibers/ferrofluid (Fe3O4 particles) composite sheets using novolac resin via compression molding for electromagnetic shielding applications. The optimized formulation has been achieved to get an excellent combination of thermal, mechanical, and electrical properties of the composite sheet. Structural and morphological studies were carried out by x-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Polypyrrole/carbon fibers composite sheets shows maximum flexural strength and a flexural modulus of 62.4 ± 1 MPa and 0.60 ± 0.02 GPa, respectively, with total shielding effectiveness of 22.8 dB in the Ku-band (12.4-18 GHz) but when ferrofluid is added to the polypyrrole/carbon fibers composite system, flexural strength increases to 92.3 ± 1 MPa and the same trend has been observed for flexural modulus with a value of 0.65 ± 0.04 GPa. This multiphase lightweight polypyrrole composite sheet having 34 vol.% of carbon fibers and 4 vol.% of Fe3O4 nanoparticles offers total shielding effectiveness of 31.9 dB (>99.99% attenuation) in the Ku-band (12.4-18 GHz) frequency range with a thickness of ˜1.25 mm. This is accredited to high dielectric losses and magnetic losses in conducting composite sheets. The observed results suggest that lightweight compression molded polypyrrole composite sheets could be a potential commercial alternative for electromagnetic shielding applications.

  1. Graphite Sheet Coating for Improved Thermal Oxidative Stability of Carbon Fiber Reinforced/PMR-15 Composites

    Science.gov (United States)

    Campbell, Sandi; Papadopoulos, Demetrios; Heimann, Paula; Inghram, Linda; McCorkle, Linda

    2005-01-01

    Expanded graphite was compressed into graphite sheets and used as a coating for carbon fiber reinforced PMR-15 composites. BET analysis of the graphite indicated an increase in graphite pore size on compression, however the material was proven to be an effective barrier to oxygen when prepegged with PMR-15 resin. Oxygen permeability of the PMR-15/graphite was an order of magnitude lower than the compressed graphite sheet. By providing a barrier to oxygen permeation, the rate of oxidative degradation of PMR-15 was decreased. As a result, the composite thermo-oxidative stability increased by up to 25%. The addition of a graphite sheet as a top ply on the composites yielded little change in the material's flexural strength or interlaminar shear strength.

  2. AC/TiO2/Rubber Composite Sheet Catalysts; Fabrication, Characterization and Photocatalytic Activities

    Directory of Open Access Journals (Sweden)

    Sriwong Chaval

    2015-01-01

    Full Text Available The AC/TiO2/Rubber (ACTR composite sheets weresuccessfully fabricated by a simply mixing of fixed TiO2 suspension and natural rubber latex (60% HA contents withthe varyingamounts of activated carbon (AC suspension, followed by stirring, pouring into apetri dish mold, drying at room temperature (RT, after that taking out from a mold, reversing and drying again at RT. Then, the as-fabricated ACTR composite sheets were characterized by X-ray diffractometer (XRD, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR, energy dispersive X-ray spectroscopy (EDS and scanning electron microscopy (SEMtechniques. The photocatalytic efficiencies of all ACTR composite sheet samples were evaluated by photo degrading of methylene blue (MB dye solution under UV light irradiation. The results showed that the photocatalytic activity of ACTR sheet with10.0wt%AC loading has the highest efficiency for the photo degradation of MB dye than the other sheets. This is due to the fact that it is relatively with the synergistic effect of well-combined titanium dioxide catalyst and activated carbon adsorbent.

  3. Simulation of stress in an innovative combination of composite with metal sheet

    Science.gov (United States)

    Wróbel, A.; Płaczek, M.; Buchacz, A.; Słomiany, A.

    2016-08-01

    In this article research of stress impact in multi-point connection glass epoxy composite with a metal sheet with a rivet nuts was presented. Composite materials are increasingly used because of the good mechanical properties and low price. The laminates are composites of a layer structure, characterized by very high strength in the direction of the fibers, their weakness is not good toughness in a direction perpendicular to the layers. Mainly checking of displacements and stresses generated on the sheet as a result of pneumatic actuators load for composite boards was carried out. Glass-epoxy composite consisting of four layers of glass mat with a weight of 1000 g/m2 and an epoxy resin and hardener HG700 LG700 volume ratio of 38/100 was created. Next composite was fixed with steel plate with a rivet nuts and bolts. A model of laminate samples and plate was simulate in Siemens NX 8.5 software. The simulation results will determine stresses and displacements in conjunction newly designed composite sheet. Strength analysis was performed with the use of the module NX Advanced Simulation. FEM is an advanced method for solving systems of differential equations, based on the division of the field into finite elements for which the solution is approximated by specific functions, and performing the actual calculations only for nodes of this division. Due to the complexity of the created object to simplify the elements made to reduce the calculation time. This article presents the study of stresses and displacements in the composite plates joined with sheet metal, in summary of this article, the authors compare the obtainted results with the computer simulation results in the article: " The study of fix composite panel and steel plates on testing stand".

  4. Survey of 0. 1- to 16-keV/e plasma sheet ion composition

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, W.; Shelley, E.G.

    1986-03-01

    A large statistical survey of the 0.1- to 16-keV/e plasma sheet ion composition has been carried out using data obtained by the Plasma Composition Experiment on ISEE 1 between 10 and 23 R/sub E/ during 1978 and 1979. This survey includes more than 10 times the quantity of data used in earlier studies of the same topic and makes it possible to investigate in finer detail the relationship between the ion composition and the substorm activity. The larger data base also makes it possible for the first time to study the spatial distribution of the principal ion species. As found in previous studies, the ion composition has a large variance at any given value of the AE index, but a number of distinct trends emerge when the data are averaged at each activity level. During quiet conditions the plasma sheet is dominated by ions of solar origin (H/sup +/ and He/sup + +/), as found in earlier studies, and these ions are most numerous during extended periods of very low activity (AE< or approx. =30 ..gamma..). The quiet time density of these ions is particularly large in the flanks of the plasma sheet (GSM Yapprox. +- 10 R/sub E/), where it is about twice as large as it is near the central axis of the plasma sheet (Y = Z = 0). In contrast, the energy of these ions peaks near the central axis.

  5. Design recommendations for long span composite slabs with deep profiled steel sheets

    NARCIS (Netherlands)

    Brekelmans, J.W.P.M.; Daniels, B.J.; Hove, B.W.E.M. van; Koukkari, H.; Stark, J.W.B.; Schuurman, R.G.

    1997-01-01

    As part of the ECSC research project `Steel intensive shallow floor construction', design recommendations for long span composite slabs with deep profiled steel deck have been drafted. These deep profiled steel sheets have depths of at least 200 mm. Test results and design recommendations are

  6. Design recommendations for long span composite slabs with deep profiled steel sheets

    NARCIS (Netherlands)

    Brekelmans, J.W.P.M.; Daniels, B.J.; Hove, B.W.E.M. van; Koukkari, H.; Stark, J.W.B.; Schuurman, R.G.

    1997-01-01

    As part of the ECSC research project `Steel intensive shallow floor construction', design recommendations for long span composite slabs with deep profiled steel deck have been drafted. These deep profiled steel sheets have depths of at least 200 mm. Test results and design recommendations are presen

  7. Design recommendations for long span composite slabs with deep profiled steel sheets

    NARCIS (Netherlands)

    Brekelmans, J.W.P.M.; Daniels, B.J.; Hove, B.W.E.M. van; Koukkari, H.; Stark, J.W.B.; Schuurman, R.G.

    1997-01-01

    As part of the ECSC research project `Steel intensive shallow floor construction', design recommendations for long span composite slabs with deep profiled steel deck have been drafted. These deep profiled steel sheets have depths of at least 200 mm. Test results and design recommendations are presen

  8. A novel wound dressing material — fibrin–chitosan–sodium alginate composite sheet

    Indian Academy of Sciences (India)

    M Pandima Devi; M Sekar; M Chamundeswari; A Moorthy; G Krithiga; N Selva Murugan; T P Sastry

    2012-12-01

    The present study describes preparation and characterization of fibrin–chitosan–sodium alginate composite (F–C–SA) in sheet form. F–C–SA composite was prepared and characterized for its physicochemical properties like water absorption capacity, surface morphology, FTIR spectra and mechanical properties. The optimum quantities of fibrin, chitosan and sodium alginate to get better mechanical properties to composite were determined. FTIR spectrum confirmed the interaction between amino groups of chitosan, fibrin and sodium alginate and SEM studies revealed composite nature of the material.

  9. Synthesis of silanized maghemite nanoparticles onto reduced graphene sheets composites

    Science.gov (United States)

    Cosio-Castañeda, C.; Martínez-García, R.; Socolovsky, L. M.

    2014-04-01

    Novel γ-Fe2O3@APTES@rGO composites are successfully synthesized by using graphene oxide and silanized maghemite nanoparticles. Graphene oxide and maghemite were obtained by Hummers and Massart methods, respectively. The silanization process was done to functionalize maghemite surface with a controllable quantity of amino groups. Then, by adding aqueous graphene oxide suspension, the bonding between graphene oxide and silanized maghemite nanoparticles was done in refluxing conditions. Afterwards, chemical reduced graphene oxide reaction was realized by addition of hydrazine solution. The characterization of γ-Fe2O3@APTES@rGO composites was studied by X-ray Diffraction, Fourier Transformed Infrared Spectroscopy, thermogravimetric analysis and scanning electron microscopy.

  10. Anisotropy of torsional rigidity of sheet polymer composite materials

    Science.gov (United States)

    Startsev, O. V.; Kovalenko, A. A.; Nasonov, A. D.

    1999-05-01

    Wide application of polymer composite materials (PCM) in modern technology calls for detailed evaluation of their stress-strain properties in a broad temperature range. To obtain such information, we use the dynamic mechanical analysis and with the help of a reverse torsion pendulum measure the dynamic torsional rigidity of PCM bars of rectangular cross section in the temperature range up to 600 K. It is found that the temperature dependences of the dynamic rigidity of the calculated values of dynamic shear moduli are governed by the percentage and properties of the binder and fibers, the layout of fibers, the phase interaction along interfaces, etc. The principles of dynamic mechanical spectrometry are used to substantiate and analyze the parameters of anisotropy by which the behavior of a composite can be described in the temperature range including the transition of the binder from the glassy into a highly elastic state. For this purpose, the values of dynamic rigidity are measured under low-amplitude vibrations of the PCM specimens with a fiber orientation angle from 0 to 90°. It is shown that for unidirectional composites the dependence between the dynamic rigidity and the fiber orientation angle is of extreme character. The value and position of the peak depend on the type of the binder and fibers and change with temperature. It is found that the anisotropy degree of PCM is dictated by the molecular mobility and significantly changes in the temperature range of transition of the binder and reinforcement from the glassy into a highly elastic state (in the case of SVM fibers). The possibility of evaluating the anisotropy of composites with other reinforcement schemes, in particular, of orthogonally reinforced PCMs, is shown.

  11. STUDY ON STRESS CONCENTRATIONS IN AN INTRAPLY HYBRID COMPOSITE SHEET

    Institute of Scientific and Technical Information of China (English)

    曾庆敦; 黄小清; 林雪慧

    2001-01-01

    A reasonably, simply and accurately modified shear-lag model was proposed.Based on the model, the stress redistributions due to the failure of some fibers in an intraply hybrid composite under tension were analyzed. The results show that the present calculating stress concentration factors very coincide with Fukuda and Chou' s results, thus verifying the reasonableness and correctness of the present model and methods.

  12. Comparison of plasma sheet ion composition with the IMF and solar wind plasma

    Science.gov (United States)

    Lennartsson, W.

    Plasma sheet energetic ion data (0.1- to 16 keV/e) obtained by the Plasma Composition Experiment on ISEE-1 between 10 and 23 earth radii are compared with concurrent IMF and solar wind plasma data. The densities of H(+) and He(++) ions in the plasma sheet are found to be the highest, and the most nearly proportional to the solar wind density, when the IMF B(z) is not northward. The density of terrestrial O(+) ions increases strongly with increasing magnitude of the IMF, in apparent agreement with the notion that the IMF plays a fundamental role in the electric coupling between the solar wind and the ionosphere.

  13. Bending behavior of thermoplastic composite sheets viscoelasticity and temperature dependency in the draping process

    CERN Document Server

    Ropers, Steffen

    2017-01-01

    Within the scope of this work, Steffen Ropers evaluates the viscoelastic and temperature-dependent nature of the bending behavior of thermoplastic composite sheets in order to further enhance the predictability of the draping simulation. This simulation is a useful tool for the development of robust large scale processes for continuously fiber-reinforced polymers (CFRP). The bending behavior thereby largely influences the size and position of wrinkles, which are one of the most common processing defects for continuously fiber-reinforced parts. Thus, a better understanding of the bending behavior of thermoplastic composite sheets as well as an appropriate testing method along with corresponding material models contribute to a wide-spread application of CFRPs in large scale production. Contents Thermoplastic Prepregs Draping Simulation of Thermoplastic Prepregs Bending Characterization of Textile Composites Modeling of Bending Behavior Target Groups Researchers and students in the field of polymer, lightweight,...

  14. Hierarchical-structured anatase-titania/cellulose composite sheet with high photocatalytic performance and antibacterial activity.

    Science.gov (United States)

    Luo, Yan; Huang, Jianguo

    2015-02-02

    Bulk hierarchical anatase-titania/cellulose composite sheets were fabricated by subjecting an ultrathin titania gel film pre-deposited filter paper to a solvo-co-hydrothermal treatment by using titanium butoxide as the precursor to grow anatase-titania nanocrystallites on the cellulose nanofiber surfaces. The titanium butoxide specie is firstly absorbed onto the nanofibers of the cellulose substance through a solvothermal process, which was thereafter hydrolyzed and crystallized upon the subsequent hydrothermal treatment, leading to the formation of fine anatase-titania nanoparticles with sizes of 2-5 nm uniformly anchored on the cellulose nanofibers. The resulting anatase-titania/cellulose composite sheet shows a significant photocatalytic performance towards degradation of a methylene blue dye, and introduction of silver nanoparticles into the composite sheet yields an Ag-NP/anatase-titania/cellulose composite material possessing excellent antibacterial activity against both Gram-positive and Gram-negative bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Thermal conductivity of bulk boron nitride nanotube sheets and their epoxy-impregnated composites

    Energy Technology Data Exchange (ETDEWEB)

    Jakubinek, Michael B.; Kim, Keun Su; Simard, Benoit [Security and Disruptive Technologies, Division of Emerging Technologies, National Research Council Canada, Ottawa, ON (Canada); Niven, John F. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS (Canada); Johnson, Michel B. [Institute for Research in Materials, Dalhousie University, Halifax, NS (Canada); Ashrafi, Behnam [Aerospace, Division of Engineering, National Research Council Canada, Montreal, QC (Canada); White, Mary Anne [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS (Canada); Institute for Research in Materials, Dalhousie University, Halifax, NS (Canada); Department of Chemistry, Dalhousie University, Halifax, NS (Canada)

    2016-08-15

    The thermal conductivity of bulk, self-supporting boron nitride nanotube (BNNT) sheets composed of nominally 100% BNNTs oriented randomly in-plane was measured by a steady-state, parallel thermal conductance method. The sheets were either collected directly during synthesis or produced by dispersion and filtration. Differences between the effective thermal conductivities of filtration-produced BNNT buckypaper (∝1.5 W m{sup -1} K{sup -1}) and lower-density as-synthesized sheets (∝0.75 W m{sup -1} K{sup -1}), which are both porous materials, were primarily due to their density. The measured results indicate similar thermal conductivity, in the range of 7-12 W m{sup -1} K{sup -1}, for the BNNT network in these sheets. High BNNT-content composites (∝30 wt.% BNNTs) produced by epoxy impregnation of the porous BNNT network gave 2-3 W m{sup -1} K{sup -1}, more than 10 x the baseline epoxy. The combination of manufacturability, thermal conductivity, and electrical insulation offers exciting potential for electrically insulating, thermally conductive coatings and packaging. Thermal conductivity of free-standing BNNT buckypaper, buckypaper composites, and related materials at room temperature. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Design of the composite flooring slab with profiled sheets t-153 (ruukki) for a residential building

    OpenAIRE

    Alysheva, Stanislava

    2015-01-01

    The purpose of the thesis was to analyse the structure of the composite slab with profiled sheets as permanent formwork; to work with Russian building norms and carry out the limit state design in order to determine characteristics of the structure and find out if it can be used in residential buildings. The study was commissioned by engineers of company Ruukki rus as they are willing to expand their market from designing industrial buildings to residential apartments. An excel file was cr...

  17. Physico-Chemical, Functional and Rheological Characterization of Biodegradable Pellets and Composite Sheets

    Directory of Open Access Journals (Sweden)

    Jan Kulsum

    2016-01-01

    Full Text Available Deoiled rice bran, paddy husk, cashew nut shell liquid and glycerol were extruded into pellets and further pressed into composites. Processing and plasticizer type had significant effect on physico-chemical, functional, rheological and morphological properties of pellets and composites. Specific mechanical energy of the pellets containing cashew nut shell liquid as plasticizer was higher than those containing glycerol. The maximum hardness and bulk density were obtained for pellets prepared from cashew nut shell liquid. Water binding capacity and water solubility index of both pellets and composites were highest for samples containing glycerol as plasticizer. A significant change in functional properties during processing was observed among raw materials, pellets and the final product (composite sheets.

  18. Embedded Aligned Carbon Nanotube Sheets for Strain and Damage sensing in Composite Structures

    Science.gov (United States)

    Aly, Karim Aly Abdelomoaty Elsayed

    The world demand for fiber reinforced composite materials has been steadily increasing because of the widespread adoption of this class of material in many markets. The automotive, aerospace, marine and energy sectors account for a large percentage of this grow. Outstanding fatigue performance, high specific stiffness and strength, and low density are among the most important properties that fiber reinforced polymer composites offer. Furthermore, their properties can be tailored to meet the specific needs of the final applications. However, this class of material is composed of multiple layers of inhomogeneous and anisotropic constituents, i.e. fibers and matrix. Therefore, this laminated nature make the composite material prone to intrinsic damage including interfacial debonding and delamination and their strength and failure are dependent on the fiber architecture and direction of the applied stresses. Consequently, it is of prime importance to monitor the health of these structures. New and improved methods for early detection of damage and structural health monitoring of composite materials may allow for enhanced reliability, lifetime and performance while minimizing maintenance time during a composite part's service life. Over the last few decades different non-destructive methods and materials have been investigated for use as strain sensors. Since the discovery of carbon nanotubes (CNTs), they have attracted much research interest due to their superior electrical, thermal and mechanical properties as well as their high aspect ratio. In this context, CNTs have been used in the recent years to enable sensing capabilities. In this dissertation, the usage of CNTs for performing strain and damage sensing in composites is evaluated. This was enabled by embedding aligned sheets of two millimeters long, interconnected CNTs into laminated structures that were then subjected to different forms of mechanical loading. The localization of the CNT sheets inside the host

  19. A study of the formation and dynamics of the Earth's plasma sheet using ion composition data

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, O.W.

    1994-04-01

    Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.

  20. Transparent actuators and robots based on single-layer superaligned carbon nanotube sheet and polymer composites

    Science.gov (United States)

    Chen, Luzhuo; Weng, Mingcen; Zhang, Wei; Zhou, Zhiwei; Zhou, Yi; Xia, Dan; Li, Jiaxin; Huang, Zhigao; Liu, Changhong; Fan, Shoushan

    2016-03-01

    Transparent actuators have been attracting emerging interest recently, as they demonstrate potential applications in the fields of invisible robots, tactical displays, variable-focus lenses, and flexible cellular phones. However, previous technologies did not simultaneously realize macroscopic transparent actuators with advantages of large-shape deformation, low-voltage-driven actuation and fast fabrication. Here, we develop a fast approach to fabricate a high-performance transparent actuator based on single-layer superaligned carbon nanotube sheet and polymer composites. Various advantages of single-layer nanotube sheets including high transparency, considerable conductivity, and ultra-thin dimensions together with selected polymer materials completely realize all the above required advantages. Also, this is the first time that a single-layer nanotube sheet has been used to fabricate actuators with high transparency, avoiding the structural damage to the single-layer nanotube sheet. The transparent actuator shows a transmittance of 72% at the wavelength of 550 nm and bends remarkably with a curvature of 0.41 cm-1 under a DC voltage for 5 s, demonstrating a significant advance in technological performances compared to previous conventional actuators. To illustrate their great potential usage, a transparent wiper and a humanoid robot ``hand'' were elaborately designed and fabricated, which initiate a new direction in the development of high-performance invisible robotics and other intelligent applications with transparency.Transparent actuators have been attracting emerging interest recently, as they demonstrate potential applications in the fields of invisible robots, tactical displays, variable-focus lenses, and flexible cellular phones. However, previous technologies did not simultaneously realize macroscopic transparent actuators with advantages of large-shape deformation, low-voltage-driven actuation and fast fabrication. Here, we develop a fast approach to

  1. EVALUATION OF NATURAL FREQUENCY AND DAMPING OF PROFILED STEEL SHEET DRY BOARD COMPOSITE PANEL

    Directory of Open Access Journals (Sweden)

    W.H. WAN BADARUZZAMAN

    2011-12-01

    Full Text Available This paper evaluates the natural frequency and damping coefficient of Profiled Steel Sheet Dry Board (PSSDB composite flooring panel system. The PSSDB composite flooring panel consists of dry board attached to the top surface of profiled steel sheet by self-drilling and self-tapping screws. This PSSDB composite panel has been used successfully as flooring system in few construction projects within Malaysia. As a lightweight flooring system, human induced vibration is becoming increasingly vital serviceability and safety issues for such panel when it is covering relatively longer span or area. Therefore, it is important to evaluate the factors affecting the serviceability performance and hence, to consider the effects of vibration in building such flooring system. This research is focused mainly on the fundamental frequency and damping coefficient of such floor panel. The influence of span length, board thickness, and connectors spacing on fundamental frequency are evaluated. It is shown that for the panels considered in this paper; up to the span length of 3.5 m the fundamental frequency is above the limiting minimum value of 8Hz and hence, it can be concluded that such composite floor panel with practical span length will be comfortable to the occupants of building in terms of human induced vibration.

  2. Novel multifunctional composites based on carbon nanotube sheets and yarns: Synthesis, fabrication, properties and applications

    Science.gov (United States)

    Lepro Chavez, Xavier N.

    Multiwalled carbon nanotube (MWNT) aligned sheets directly drawn from forests and derived yarns have recently attracted wide attention because of their exhibited mechanical, electronic, photonic and optical properties. Unfortunately, the supply of drawable forests is currently limited since the set of experimental conditions required to obtain adequate forest morphology is rather narrow, thus restricting the advance towards large scale applications. This work starts by addressing this issue by showing that the correct preparation of alternative substrates, such as thin metallic sheets, can produce the forest morphology required for solid-state drawability and increase the attainable surface for forest harvesting without further enlargement of the currently used chemical vapor deposition (CVD) reactor chamber. Also, it explores suitable ways to quantify the alignment of MWNTs in forests and by comparing them with spinnable ones, provides a range of alignment distribution where forest drawability can be reasonably expected. Next, this work presents procedures that can add functionality to the MWNT free-standing sheets without strongly affecting their mechanical integrity, nanotube alignment or individual morphology. Proved examples, such as free-standing sheets of catalytic-active, highly capacity (39 F/g), aligned nitrogen-doped MWNTs and silicon-based ceramic conformationally coated MWNTs that can be easily twisted into yarns, are examined in different chapters. Moreover, we show that MWNT sheets can be used for templating materials other than carbon into nanostructured arrays by preparing sheets of aligned silicon oxide nanotubes. Similar to MWNT sheets, these nanotube based materials can be used as host to confine functional unspinnable materials (up to 95 wt.%) by twisting them together into biscrolled yarns, suitable for applications as superconductors, lithium-ion batteries, fuel cells catalysts and photocatalysis. Such biscrolled yarns have a twist

  3. Solvothermal Synthesis of Mn3O4 Nanoparticle/Graphene Sheet Composites and Their Supercapacitive Properties

    Directory of Open Access Journals (Sweden)

    Y. F. Liu

    2014-01-01

    Full Text Available Mn3O4 nanoparticle/graphene sheet (GM composites were synthesized via a one-pot and low-cost solvothermal process in an ethanol solution. The as-prepared materials were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Results showed that the nanosized Mn3O4 particles had tetragonal hausmannite structure and were successfully loaded on the graphene sheets. Moreover, the electrochemical performances of GM composites produced by different mass percents of Mn2+/graphite oxide (GO were evaluated by means of cyclic voltammetry and galvanostatic charge-discharge studies. The composite prepared with Mn2+/GO mass percent of 10 : 90 showed a high specific capacitance of 245 F/g at 5 mV/s in the 6 M KOH solution and better long-term stability along with 81% of its initial capacitance after 1200 cycles at 0.5 A/g.

  4. Plasma sheet ion composition at various levels of geomagnetic and solar activity

    Science.gov (United States)

    Lennartsson, W.

    1987-08-01

    The data obtained in the earth's plasma sheet by the Plasma Composition Experiment on the ISEE-1 spacecraft are briefly reexamined. The data are shown in the form of statistically averaged bulk parameters for the four major ions H(+), He(2+), He(+), and O(+) to illustrate the apparent mixture of solar and terrestrial ions, a mixture that varies with geomagnetic and other conditions. Some major differences in the statistical properties of different ions, which may have a bearing on the physics of the solar wind-magnetosphere interaction, are highlighted.

  5. Poor fluorinated graphene sheets carboxymethylcellulose polymer composite mode locker for erbium doped fiber laser

    Science.gov (United States)

    Mou, Chengbo; Arif, Raz; Lobach, Anatoly S.; Khudyakov, Dmitry V.; Spitsina, Nataliya G.; Kazakov, Valery A.; Turitsyn, Sergei; Rozhin, Aleksey

    2015-02-01

    We report poor fluorinated graphene sheets produced by thermal exfoliation embedding in carboxymethylcellulose polymer composite (GCMC) as an efficient mode locker for erbium doped fiber laser. Two GCMC mode lockers with different concentration have been fabricated. The GCMC based mode locked fiber laser shows stable soliton output pulse shaping with repetition rate of 28.5 MHz and output power of 5.5 mW was achieved with the high concentration GCMC, while a slightly higher output power of 6.9 mW was obtained using the low concentration GCMC mode locker.

  6. Poor fluorinated graphene sheets carboxymethylcellulose polymer composite mode locker for erbium doped fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chengbo, E-mail: mouc1@aston.ac.uk, E-mail: a.rozhin@aston.ac.uk; Turitsyn, Sergei; Rozhin, Aleksey, E-mail: mouc1@aston.ac.uk, E-mail: a.rozhin@aston.ac.uk [Aston Institute of Photonic Technologies, Aston University, Aston Triangle, Birmingham B4 7ET (United Kingdom); Arif, Raz [Aston Institute of Photonic Technologies, Aston University, Aston Triangle, Birmingham B4 7ET (United Kingdom); Physics Department, Faculty of Science, University of Sulaimani, Sulaimani, Kurdistan Region (Iraq); Lobach, Anatoly S.; Spitsina, Nataliya G. [Institute of Problems of Chemical Physics RAS, Ac. Semenov Av. 1, Chernogolovka, Moscow Region 142432 (Russian Federation); Khudyakov, Dmitry V. [Institute of Problems of Chemical Physics RAS, Ac. Semenov Av. 1, Chernogolovka, Moscow Region 142432 (Russian Federation); Physics Instrumentation Center of the Institute of General Physics A.M. Prokhorov Russian Academy of Sciences, Troitsk, Moscow Region 142190 (Russian Federation); Kazakov, Valery A. [Keldysh Center, Onezhskaya 8, Moscow 125438 (Russian Federation)

    2015-02-09

    We report poor fluorinated graphene sheets produced by thermal exfoliation embedding in carboxymethylcellulose polymer composite (GCMC) as an efficient mode locker for erbium doped fiber laser. Two GCMC mode lockers with different concentration have been fabricated. The GCMC based mode locked fiber laser shows stable soliton output pulse shaping with repetition rate of 28.5 MHz and output power of 5.5 mW was achieved with the high concentration GCMC, while a slightly higher output power of 6.9 mW was obtained using the low concentration GCMC mode locker.

  7. Measuring Ultrasonic Acoustic Velocity in a Thin Sheet of Graphite Epoxy Composite

    Science.gov (United States)

    2008-01-01

    A method for measuring the acoustic velocity in a thin sheet of a graphite epoxy composite (GEC) material was investigated. This method uses two identical acoustic-emission (AE) sensors, one to transmit and one to receive. The delay time as a function of distance between sensors determines a bulk velocity. A lightweight fixture (balsa wood in the current implementation) provides a consistent method of positioning the sensors, thus providing multiple measurements of the time delay between sensors at different known distances. A linear fit to separation, x, versus delay time, t, will yield an estimate of the velocity from the slope of the line.

  8. Graphene sheets stacked polyacrylate latex composites for ultra-efficient electromagnetic shielding

    Science.gov (United States)

    Li, Yong; Zhang, Song; Ni, Yuwei

    2016-07-01

    Graphene sheets (GS) are at the forefront of electromagnetic interference (EMI) shielding/attenuation materials science research because of their excellent electrical properties (Wen B et al 2014 Adv. Mater. 26 3484, Zhang Y et al 2015 Adv. Mater. 27 2049). GS/polyacrylate (PA) composites were prepared using a solvent-free latex technology, which favored the build-up of a segregated GS architecture stacked in the polymer matrix. GS were obtained from graphite flakes (GF) via a mechanical delamination approach in water. The microstructure, electrical, dielectric and electromagnetic shielding properties of the GS/PA composites were correlated in this manuscript. A remarkably low percolation threshold of ˜0.11 mass per cent for room-temperature electrical conductivity was obtained in the GS/PA composites owing to the stacked architecture of GS with high aspect ratios. This unique nanostructured GS architecture not only enhanced the electrical conductivity of composites, but also dramatically increased complex permittivity by inducing strong Maxwell-Wagner-Sillars (MWS) polarization at the highly conductive GS/non-conductive PA interfaces. The EMI shielding effectiveness (SE) of these composites was enhanced with increasing GS content, and the composite with 6 wt% GS loading exhibited a high EMI SE of ˜66 dB over a frequency of 8.2-12.4 GHz, resulting from the pronounced conduction loss, dielectric relaxation, and multi-scattering.

  9. Improvements in processing characteristics and engineering properties of wood flour-filled high density polyethylene composite sheeting in the presence of hollow glass microspheres

    Science.gov (United States)

    Baris Yalcin; Steve E Amos; Andrew S D Souza; Craig M Clemons; I Sedat Gunes; Troy K Ista

    2012-01-01

    Hollow glass microspheres were introduced into wood flour/high density polyethylene composites by melt compounding in a twin-screw extruder. The prepared composites were subsequently converted to extruded profiles in order to obtain composite sheeting. The presence of hollow glass microspheres highly reduced the density of the extruded sheets down to 0.9 g/cc, while...

  10. Survey of 0.1- to 16-keV/e plasma sheet ion composition

    Science.gov (United States)

    Lennartsson, W.; Shelley, E. G.

    1986-03-01

    An analysis is performed of all plasma sheet data collected in 1978-79 in order to discern statistical trends in the data. Attention is focused on the bulk parameters of 0.1-16 keV/e plasma sheet ions detected by the Plasma Composition Experiment on the ISEE 1 satellite. The data were collected at 10-23 earth radii, and are averaged for various levels of activity in the AE index. Solar H(+) and He(2+) ions dominate during quiet periods and possess energies similar to those of the solar wind when the quiet period lasts several hours. Increasing AE index values eventually lead to a replacement of the solar ions with terrestrial ions, particularly O(+), which can have an average energy density of 3-4 keV/e at every activity level. The solar ions, however, increase in energy as their density decreases. The O(+) density is highest near the local midnight and becomes the most numerous during highly disturbed conditions. Finally, the O(+) density was observed to increase by a factor of three over the monitoring period, possibly due to enhanced solar EUV radiation.

  11. Experimental Study on Tensile Properties of a Novel Porous Metal Fiber/Powder Sintered Composite Sheet

    Directory of Open Access Journals (Sweden)

    Shuiping Zou

    2016-08-01

    Full Text Available A novel porous metal fiber/powder sintered composite sheet (PMFPSCS is developed by sintering a mixture of a porous metal fiber sintered sheet (PMFSS and copper powders with particles of a spherical shape. The characteristics of the PMFPSCS including its microstructure, sintering density and porosity are investigated. A uniaxial tensile test is carried out to study the tensile behaviors of the PMFPSCS. The deformation and failure mechanisms of the PMFSCS are discussed. Experimental results show that the PMFPSCS successively experiences an elastic stage, hardening stage, and fracture stage under tension. The tensile strength of the PMFPSCS is determined by a reticulated skeleton of fibers and reinforcement of copper powders. With the porosity of the PMFSS increasing, the tensile strength of the PMFPSCS decreases, whereas the reinforcement of copper powders increases. At the elastic stage, the structural elastic deformation is dominant, and at the hardening stage, the plastic deformation is composed of the structural deformation and the copper fibers’ plastic deformation. The fracture of the PMFPSCS is mainly caused by the breaking of sintering joints.

  12. Flattening simulations of 3D thick sheets made of fiber composite materials

    Directory of Open Access Journals (Sweden)

    Kotaro Morioka

    2015-04-01

    Full Text Available Recently, fiber composite materials have been attracting attention from industry because of their remarkable material characteristics, including light weight and high stiffness. However, the costs of products composed of fiber materials remain high because of the lack of effective manufacturing and designing technologies. To improve the relevant design technology, this paper proposes a novel simulation method for deforming fiber materials. Specifically, given a 3D model with constant thickness and known fiber orientation, the proposed method simulates the deformation of a model made of thick fiber-material. The method separates a 3D sheet model into two surfaces and then flattens these surfaces into two dimensional planes by a parameterization method with involves cross vector fields. The cross vector fields are generated by propagating the given fiber orientations specified at several important points on the 3D model. Integration of the cross vector fields gives parameterization with low-stretch and low-distortion.

  13. Composite Aluminum-Copper Sheet Material by Friction Stir Welding and Cold Rolling

    Science.gov (United States)

    Kahl, S.; Osikowicz, W.

    2013-08-01

    An aluminum alloy and a pure copper material were butt-joined by friction stir welding and subsequently cold rolled. The cold-rolling operation proved to be very advantageous because small voids present after friction stir welding were closed, the interface area per material thickness was enlarged, a thin intermetallic layer was partitioned, and the joint was strengthened by strain hardening. Tensile test specimens fractured in the heat-affected zone in the aluminum material; tensile strengths of the joints exceeded the tensile strengths of the base materials and were as high as 335 MPa. During soft annealing of the composite material, a 6-8-μm-thick intermetallic layer was grown at the interface. Nevertheless, tensile fracture still occurred in the heat-affected zone of the aluminum material. Electrical resistivity of the joint was smaller than resistivity of the aluminum material. Production of such composite material would result in coiled sheet material that could be subjected to further treatments such as electroplating and forming operations in an efficient and economically viable manner. The new composite material is promising for emerging automotive and industrial electrical applications.

  14. Designing of Multiphase Fly Ash/MWCNT/PU Composite Sheet Against Electromagnetic Environmental Pollution

    Science.gov (United States)

    Gujral, Parth; Varshney, Swati; Dhawan, S. K.

    2016-06-01

    Fly ash and multiwalled carbon nanotubes (MWCNT) reinforced multiphase polyurethane (PU) composite sheets have been fabricated by using a solution casting technique. Utilization of fly ash was the prime objective in order to reduce environmental pollution and to enhance the shielding properties of PU polymer. Our study proves that fly ash particles with MWCNTs in a PU matrix leads to novel hybrid high performance electromagnetic shielding interference material. Scanning electron microscopy confirms the existence of fly ash particles along with MWCNTs in a PU matrix. This multiphase composite shows total shielding effectiveness of 35.8 dB (>99.99% attenuation) in the Ku-band (12.4-18 GHz) frequency range. This is attributed to high dielectric losses of reinforcement present in the polymers matrix. The Nicolson-Ross-Weir algorithm has been applied to calculate the electromagnetic attributes and dielectric parameters of the PU samples by using scattering parameters ( S 11, S 22, S 12, S 21). The synthesized multiphase composites were further characterized by using x-ray diffraction, Fourier transform infrared spectroscopy, and thermo gravimetric analysis.

  15. Substorm effects on the plasma sheet on composition on March 22, 1979 (CDAW 6)

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, W.; Sharp, R.D.; Zwickl, R.D.

    1985-02-01

    Data from the Plasma Composition Experiment on ISSE 1, covering the energy range 0.1--16 keV/e, show that a dramatic change took place in the plasma sheet ion composition in conjunction with the magnetic substorm activity on March 22, 1979. Beginning about 1124 UT the ion population at the ISEE 1 location changed from what appeared to be predominantly ions from the solar wind to a mixture of comparable numbers of solar wind and terrestrial ions. ISEE 1 was inbound in the predawn sector during this time, and the plasma composition experiment provided data from Rapprox. =21 R/sub E/ and LTapprox. =0130, down to Rapprox. =3 R/sub E/ and LTapprox. =0530. Prior to the substorm activity about 90--95% of the ion density was due to H/sup +/ and He/sup + +/ ions, which appeared to be mostly of solar wind origin. The H/sup +/ and He/sup + +/ components, each approximated by a Maxwell-Boltzmann distribution, had a temperature ratio T(He/sup + +/)/T(H/sup +/)approx. =4 and a density ratio n(He/sup + +/)/n(H/sup +/)approx. =1.5--3%. Both values are consistent with measurements made concurrently in the solar wind by the plasma experiment on ISSE 3. The remaining 5--10% of the density was due mainly to O/sup +/ and He/sup +/ ions of ionospheric origin. All four ion populations had broad energy spectra with mean energies of several keV/e.

  16. Long-term variations in the plasma sheet ion composition and substorm occurrence over 23 years

    Science.gov (United States)

    Nosé, Masahito

    2016-12-01

    The Geotail satellite has been operating for almost two solar cycles (~23 years) since its launch in July 1992. The satellite carries the energetic particle and ion composition (EPIC) instrument that measures the energetic ion flux (9.4-212 keV/e) and enables the investigation of long-term variations of the ion composition in the plasma sheet for solar cycles 22-24. From the statistical analysis of the EPIC data, we find that (1) the plasma ion mass ( M) is approximately 1.1 amu during the solar minimum, whereas it increases to 1.5-2.7 amu during the solar maximum; (2) the increases in M seem to have two components: a raising of the baseline levels (~1.5 amu) and a large transient enhancement (~1.8-2.7 amu); (3) the baseline level change of M correlates well with the Mg II index, which is a good proxy for the solar extreme ultraviolet (EUV) or far ultraviolet (FUV) irradiance; and (4) the large transient enhancement of M is caused by strong magnetic storms. We also study the long-term variations of substorm occurrences in 1992-2015 that are evaluated with the number of Pi2 pulsations detected at the Kakioka observatory. The results suggest no clear correlation between the substorm occurrence and the Mg II index. Instead, when the substorms are classified into externally triggered events and non-triggered events, the number of the non-triggered events and the Mg II index are negatively correlated. We interpret these results that the increase in the solar EUV/FUV radiation enhances the supply of ionospheric ions (He+ and O+ ions) into the plasma sheet to increase M, and the large M may suppress spontaneous plasma instabilities initiating substorms and decrease the number of the non-triggered substorms. The present analysis using the unprecedentedly long-term dataset covering ~23 years provides additional observational evidence that heavy ions work to prevent the occurrence of substorms.

  17. Cytotoxicity of Silver Nanoparticle and Chitin-Nanofiber Sheet Composites Caused by Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Jun Kinoda

    2016-10-01

    Full Text Available Size-controlled spherical silver nanoparticles (<10 nm and chitin-nanofiber sheet composites (Ag NPs/CNFS have previously been reported to have strong antimicrobial activity in vitro. Although Ag NPs/CNFS have strong antimicrobial activity, their cytotoxicity has not been investigated. This study was performed to evaluate the effects of Ag NPs/CNFS on cytotoxicity for fibroblasts in vitro and healing delay of wound repair in vivo, focused on oxidative stress. Cytotoxic activities of Ag NPs/CNFS were investigated using a fibroblast cell proliferation assay, nitric oxide/nitrogen dioxide (NO/NO2 measurement of the cell lysates in vitro, inhibitory effects of Ag NPs/CNFS on healing-impaired wound repair using diabetic mice in vivo, 8-hydroxy-2′-deoxyguanosine (8-OHdG immunohistochemical staining of the skin sections, and generation of carbonyl protein in the wound was performed to evaluate cytotoxicity with oxidative stress. Ag NPs/CNFS exhibited cytotoxicity for fibroblasts and a significant increase of total NO/NO2 levels in the cell lysates in vitro and increased levels of 8-OHdG and carbonyl proteins in vivo. Although wound repair in the continuously Ag NPs/CNFS-treated group was delayed, it could be mitigated by washing the covered wound with saline. Thus, Ag NPs/CNFS may become accepted as an anti-infectious wound dressing.

  18. Mechanical response of a living human epidermal keratinocyte sheet as measured in a composite diaphragm inflation experiment.

    Science.gov (United States)

    Selby, John C; Shannon, Mark A

    2007-01-01

    Sheets of normal human epidermal keratinocytes (NHEKs) were reconstituted in vitro on tensed but highly compliant, freestanding polydimethylsiloxane (PDMS) membranes, 5.0 mm in diameter and 10 mum thick. NHEK-PDMS composite diaphragm (CD) specimens were then subjected to cyclical axisymmetric inflation tests to investigate epithelial sheet rheology under conditions of physiologically severe deformations (~50% nominal polar biaxial strains). Because the compliance of the specially formulated PDMS membrane was greater than that of the attached cell layer, the finite load-deformation behavior (mechanical response) of the living NHEK sheet was inferred from differences between the mechanical behavior of the CD specimen and the response of the underlying PDMS membrane measured prior to cell culture. In these composite diaphragm inflation (CDI) experiments, interconnected NHEKs exhibited rheological behaviors that were suggestive of a viscoelastic-plastic stress response. Remarkably, specimens returned to quiescent culture following a sequence of inflation tests recovered at least 80% of their original ability to store elastic strain energy, evidence of biological adaptation and recovery or restitutio ad integrum. Unlike methodologies that assay the morphological or biochemical response of cultured cells to an applied mechanostimulus, CDI experiments can be used to probe the load-bearing functions of desmosomes and adherens junctions within a living epithelial sheet, as well as to assess the rheological behaviors of the intermediate filament and microfilament networks that these cell-cell junctions serve to interconnect.

  19. Smart three-dimensional lightweight structure triggered from a thin composite sheet via 3D printing technique.

    Science.gov (United States)

    Zhang, Quan; Zhang, Kai; Hu, Gengkai

    2016-02-29

    Complex fabrication process and expensive materials have restricted the development of smart three-dimensional (3D) lightweight structures, which are expected to possess self-shaping, self-folding and self-unfolding performances. Here we present a simple approach to fabricate smart lightweight structures by triggering shape transformation from thin printed composite sheets. The release of the internal strain in printed polymer materials enables the printed composite sheet to keep flat under heating and transform into a designed 3D configuration when cooled down to room temperature. The 3D lightweight structure can be switched between flat and 3D configuration under appropriate thermal stimuli. Our work exploits uniform internal strain in printed materials as a controllable tool to fabricate smart 3D lightweight structures, opening an avenue for possible applications in engineering fields.

  20. Analysis of peel strength of consisting of an aluminum sheet, anodic aluminum oxide and a copper foil laminate composite

    Science.gov (United States)

    Shin, Hyeong-Won; Lee, Hyo-Soo; Jung, Seung-Boo

    2017-01-01

    Laminate composites consisting of an aluminum sheet, anodic aluminum oxide, and copper foil have been used as heat-spreader materials for high-power light-emitting diodes (LEDs). These composites are comparable to the conventional structure comprising an aluminum sheet, epoxy adhesives, and copper foil. The peel strength between the copper foil and anodic aluminum oxide should be more than 1.0 kgf/cm in order to be applied in high-power LED products. We investigated the effect of the anodic aluminum oxide morphology and heat-treatment conditions on the peel strength of the composites. We formed an anodic aluminum oxide layer on a 99.999% pure aluminum sheet using electrochemical anodization. A Ti/Cu seed layer was formed using the sputtering direct bonding copper process in order to form a copper circuit layer on the anodic aluminum oxide layer by electroplating. The developed heat spreader, composed of an aluminum layer, anodic aluminum oxide, and a copper circuit layer, showed peel strengths ranging from 1.05 to 3.45 kgf/cm, which is very suitable for high-power LED applications.

  1. Controls on the movement and composition of firn air at the West Antarctic Ice Sheet Divide

    Directory of Open Access Journals (Sweden)

    M. O. Battle

    2011-11-01

    Full Text Available We sampled interstitial air from the perennial snowpack (firn at a site near the West Antarctic Ice Sheet Divide (WAIS-D and analyzed the air samples for a wide variety of gas species and their isotopes. We find limited convective influence (1.4–5.2 m, depending on detection method in the shallow firn, gravitational enrichment of heavy species throughout the diffusive column in general agreement with theoretical expectations, a ~10 m thick lock-in zone beginning at ~67 m, and a total firn thickness consistent with predictions of Kaspers et al. (2004. Our modeling work shows that the air has an age spread (spectral width of 4.8 yr for CO2 at the firn-ice transition. We also find that advection of firn air due to the 22 cm yr−1 ice-equivalent accumulation rate has a minor impact on firn air composition, causing changes that are comparable to other modeling uncertainties and intrinsic sample variability. Furthermore, estimates of Δage (the gas age/ice age difference at WAIS-D appear to be largely unaffected by bubble closure above the lock-in zone. Within the lock-in zone, small gas species and their isotopes show evidence of size-dependent fractionation due to permeation through the ice lattice with a size threshold of 0.36 nm, as at other sites. We also see an unequivocal and unprecedented signal of oxygen isotope fractionation within the lock-in zone, which we interpret as the mass-dependent expression of a size-dependent fractionation process.

  2. Growth of 2D sheets of a MOF on graphene surfaces to yield composites with novel gas adsorption characteristics.

    Science.gov (United States)

    Kumar, Ram; Jayaramulu, Kolleboyina; Maji, Tapas Kumar; Rao, C N R

    2014-05-28

    Homogeneous graphene-MOF composites based on a 2D pillared-bilayer MOF (Cd-PBM), {[Cd4(azpy)2(pyrdc)4(H2O)2]·9H2O}n (azpy = 4,4'-azopyridine, pyrdc = pyridine-2,3-dicarboxylate), have been synthesized, using both graphene oxide (GO) and benzoic acid functionalized graphene (BFG). The composites GO@Cd-PBM and BFG@Cd-PBM demonstrate growth of the 2D nano-sheets of MOF on the graphene surface. While the pristine MOF, Cd-PBM shows selective CO2 uptake with a single-step type-I adsorption profile, the composites show stepwise CO2 uptake with a large hysteresis. With H2O and MeOH, on the other hand, the composites show a single-step adsorption unlike the parent MOF.

  3. Hydrothermal synthesis of reduced graphene sheets/Fe2O3 nanorods composites and their enhanced electrochemical performance for supercapacitors

    Science.gov (United States)

    Yang, Wanlu; Gao, Zan; Wang, Jun; Wang, Bin; Liu, Lianhe

    2013-06-01

    Reduced graphene nanosheets/Fe2O3 nanorods (GNS/Fe2O3) composite has been fabricated by a hydrothermal route for supercapacitor electrode materials. The obtained GNS/Fe2O3 composite formed a uniform structure with the Fe2O3 nanorods grew on the graphene surface and/or filled between the graphene sheets. The electrochemical performances of the GNS/Fe2O3 hybrid supercapacitor were tested by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests in 6 M KOH electrolyte. Comparing with the pure Fe2O3 electrode, GNS/Fe2O3 composite electrode exhibits an enhanced specific capacitance of 320 F g-1 at 10 mA cm-2 and an excellent cycle-ability with capacity retention of about 97% after 500 cycles. The simple and cost-effective preparation technique of this composite with good capacitive behavior encourages its potential commercial application.

  4. Rheological and secondary structural characterization of rice flour-zein composites for noodles slit from gluten-free sheeted dough.

    Science.gov (United States)

    Jeong, Sungmin; Kim, Hee Won; Lee, Suyong

    2017-04-15

    Rice flour-zein composites in a hydrated viscoelastic state were utilized to compensate for the role of wheat gluten in gluten-free sheeted dough. The use of zein above its glass transition temperature was able to form a viscoelastic protein network of non-wheat dough with rice flour. The mixing stability and development time of the rice dough were positively increased with increasing levels of zein. The protein secondary structural analysis by FTIR spectroscopy demonstrated that the rice doughs with high levels of zein showed significant increases in β-sheet structures whose intensity was almost doubled by the use of 10% zein. The use of zein at more than 5% (w/w) successfully produced gluten-free dough sheets that could be slit into thin and long noodle strands. In addition, the composites were effective in improving the rheological characteristics of gluten-free noodle strands by increasing their maximum force to extension, compared to wheat-based noodles.

  5. Multi-Objective Parallel Test-Sheet Composition Using Enhanced Particle Swarm Optimization

    Science.gov (United States)

    Ho, Tsu-Feng; Yin, Peng-Yeng; Hwang, Gwo-Jen; Shyu, Shyong Jian; Yean, Ya-Nan

    2009-01-01

    For large-scale tests, such as certification tests or entrance examinations, the composed test sheets must meet multiple assessment criteria. Furthermore, to fairly compare the knowledge levels of the persons who receive tests at different times owing to the insufficiency of available examination halls or the occurrence of certain unexpected…

  6. Insight into biogeochemical inputs and composition of Greenland Ice Sheet surface snow and glacial forefield river catchment environments.

    Science.gov (United States)

    Cameron, Karen; Hagedorn, Birgit; Dieser, Markus; Christner, Brent; Choquette, Kyla; Sletten, Ronald; Lui, Lu; Junge, Karen

    2014-05-01

    The volume of freshwater transported from Greenland to surrounding marine waters has tended to increase annually over the past four decades as a result of warmer surface air temperatures (Bamber et al 2012, Hanna et al 2008). Ice sheet run off is estimated to make up approximately of third of this volume (Bamber et al 2012). However, the biogeochemical composition and seeding sources of the Greenland Ice Sheet supraglacial landscape is largely unknown. In this study, the structure and diversity of surface snow microbial assemblages from two regions of the western Greenland Ice Sheet ice-margin was investigated through the sequencing of small subunit rRNA genes. Furthermore, the origins of microbiota were investigated by examining correlations to molecular data obtained from marine, soil, freshwater and atmospheric environments and to geochemical analytes measured in the snow. Snow was found to contain a diverse assemblage of bacteria (Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria) and eukarya (Alveolata, Fungi, Stramenopiles and Viridiplantae). Phylotypes related to archaeal Thaumarchaeota and Euryarchaeota phyla were also identified. The structure of microbial assemblages was found to have strong similarities to communities sampled from marine and air environments, and sequences obtained from the South-West region, near Kangerlussuaq, which is bordered by an extensive periglacial expanse, had additional resemblances to soil originating communities. Strong correlations were found between bacterial beta diversity and Na+ and Cl- concentrations. These data suggest that surface snow from western regions of Greenland contain microbiota that are most likely derived from exogenous, wind transported sources. Downstream of the supraglacial environment, Greenland's rivers likely influence the ecology of localized estuary and marine systems. Here we characterize the geochemical and biotic composition of a glacial and glacial forefield fed river catchment in

  7. Ordered mesoporous carbon/graphene nano-sheets composites as counter electrodes in dye-sensitized solar cells

    Science.gov (United States)

    Shao, Leng-Leng; Chen, Ming; Ren, Tie-Zhen; Yuan, Zhong-Yong

    2015-01-01

    The composites of ordered mesoporous carbon (OMC) and graphene nano-sheets (GNS) are prepared by mixing OMC with different weight ratios of GNS, and utilized as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements demonstrate that the OMC/GNS CEs display the enhanced electron transport property and fast reduction rate of I3- in comparison with those of the individual OMC and GNS CEs, due to the combination of superior electrical conductivity of GNS and good catalytic activity of OMC. Under AM 1.5 irradiation (100 mW cm-2), the DSSCs based on the OMC/GNS CEs show a maximum power conversion efficiency of 6.82%, which is comparable to 7.08% of the cell with the conventional Pt CE at the same experimental conditions, suggesting that the OMC/GNS composites are one of advanced CE materials for low-cost DSSCs.

  8. Effect of sulfuric acid on textural properties and catalytic performance of ruthenium-containing ordered mesoporous carbon prepared via a direct RuCl3/SBA-15 hard templated method.

    Science.gov (United States)

    Lan, Guojun; Tang, Haodong; Liu, Huazhang; Ni, Jun; Li, Ying

    2014-09-01

    Ruthenium-containing ordered mesoporous carbon (Ru-OMC) catalysts with highly dispersed Ru nanoparticles semi-embedded in carbon framework were prepared via a direct RuCl3/SBA-15 hard templated method. The effect of sulfuric acid on the texture structure and catalytic performance of Ru-OMC were studied. The status of Ru nanoparticles and mesoporous structure of Ru-OMC catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), nitrogen sorption, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and CO chemisorption techniques. The addition of appropriate amount of sulfuric acid is necessary to improve the ordered mesoporous structure of Ru-OMC catalysts. The framework of carbon structure shrinks with the increase in sulfur acid contents, which is proved by a slight decrease in surface area and increase in pore diameters for Ru-OMC with different sulfur contents. The turnover frequency (TOF) for Ru-OMC reaches the highest up to 3.98 s(-1) in benzene hydrogenation with optimized sulfur acid content of 0.08 mmol/g sucrose.

  9. Sheet resistances of composite films prepared from chemically-reduced graphite oxides and multiwalled carbon nanotubes

    Science.gov (United States)

    Oh, Weontae; Kim, Daehan; Jeong, Euh Duck; Bae, Jong-Seong

    2013-12-01

    Graphite oxides (GOs) were spray-coated on a glass substrate to prepare the GO film, and the film was soaked in a HI aqueous solution to make a chemically-reduced GO (rGO) film. The rGOs were successfully prepared by using a chemical reduction of as-made GOs, but their surfaces were seriously damaged during the chemical treatments. The Sheet resistances of rGO and rGO/multiwalled carbon nanotube (MWNT) films were characterized as functions of the film's thickness and the number of MWNTs added to the rGO films.

  10. Synthesis and characterization of nickel oxide/graphene sheet/graphene ribbon composite

    Energy Technology Data Exchange (ETDEWEB)

    Lavanya, J.; Gomathi, N., E-mail: sivakumar.gomathi@gmail.com [Department of Chemistry, Indian Institute of Space Science and Technology, Thiruvananthapuram, 695547, Kerala (India)

    2016-04-13

    A novel and simple hydrothermal synthesis of nickel oxide (NiO)/graphene sheets (GNS)/graphene ribbon (GR) hybrid material is reported for the first time. The crystalline property and surface morphology of NiO/GNS/GR (NiO/HG) hybrid material is characterized by X-ray diffraction, Raman spectroscopy and Transmission electron spectroscopy. The fast electron transfer of GNS/GR along with NiO contributes an excellent electrochemical performance in the field of non-enzymatic glucose sensor.

  11. Deformation behavior of an electrodeposited nano-Ni/amorphous Fe78Si9B13 laminated composite sheet

    Directory of Open Access Journals (Sweden)

    Zhang Kaifeng

    2015-01-01

    Full Text Available A nano-Ni/amorphous Fe78Si9B13 composite sheet was prepared in the form of three-ply (Ni-Fe78Si9B13-Ni laminated structure by an electrodeposition method. The average grain size of Ni layers is about 50 nm. The interface of laminated composite was investigated with SEM equipped with energy dispersive scanning (EDS and line analysis technique. The laminated composite has a good interfacial bonding between amorphous layer and nano-Ni layers due to the mutual diffusion of atoms in Fe78Si9B13 and Ni layers during the process of electrodeposition. A maximum elongation of 115.5% was obtained when the volume fraction of nano-Ni layers (VNi was 0.77, which is greatly higher than that of monolithic amorphous Fe78Si9B13 ribbon (36.3% tested under the same conditions. Bulging tests were carried out to evaluate plastic forming properties of the Fe78Si9B13/Ni laminated composite. Under the condition of 450 °C, 4.0 MPa and 30 min, a good bulging part with the relative bulging height (RBH of 0.4 was obtained.

  12. Characterization of quasi-nano-sized TiCx-Ni-Fe thin composite sheet prepared by using self-propagating high-temperature synthesis reaction and electroforming

    Science.gov (United States)

    Choi, Yong

    2014-05-01

    Thin TiCx-Ni-Fe composites sheet was prepared by self-propagating high-temperature synthesis (SHS) and electroforming. The quasi-nano-sized titanium carbide particles were prepared by self-propagating high temperature synthesis (SHS) followed by mechanical milling and ultrasonic floating agitation for classifying particles. The composite sheet was fabricated by co-deposition of the classified titanium carbide particles in a modified Watts nickel bath containing iron chloride during nickel-iron electro-forming. Neutron diffraction showed that the non-stoichiometric number of titanium carbides formed by the SHS reaction were in the range of 0.68 to 0.97, which depended on the initial carbon sources. X-ray diffraction and electron probe micro-analysis revealed that co-deposition of the carbides in Ni-Fe bath during the electroforming process produced a thin TiCx-Ni-Fe composite sheet, in which quasi-nano-sized titanium carbides were embedded about 7 at.%. The average surface resistance of the thin composite sheet was 1.053 ohm/sq. The corrosion potential and rate of the composites in a 50% NaOH solution were -920.6 mVSHE and 8.4×10-6 Acm-2, respectively.

  13. Physico-Chemical, Functional and Rheological Characterization of Biodegradable Pellets and Composite Sheets

    OpenAIRE

    Jan Kulsum; Jan Shumaila; Riar CS; Saxena DC

    2016-01-01

    Deoiled rice bran, paddy husk, cashew nut shell liquid and glycerol were extruded into pellets and further pressed into composites. Processing and plasticizer type had significant effect on physico-chemical, functional, rheological and morphological properties of pellets and composites. Specific mechanical energy of the pellets containing cashew nut shell liquid as plasticizer was higher than those containing glycerol. The maximum hardness and bulk density were obtained for pellets prepared f...

  14. High performance asymmetric supercapacitor based on polypyrrole/graphene composite and its derived nitrogen-doped carbon nano-sheets

    Science.gov (United States)

    Zhu, Jianbo; Feng, Tianyu; Du, Xianfeng; Wang, Jingping; Hu, Jun; Wei, LiPing

    2017-04-01

    Neutral aqueous medium is a promising electrolyte for supercapacitors because it is low-cost, environmental-friendly and can achieve rapid charging/discharging with high power density. However, the energy density of such supercapacitor is significantly limited by its narrow operational voltage window. Herein, we demonstrated an effective approach to broaden the operational voltage window by fabricating an asymmetric supercapacitor (ASC) with polypyrrole/reduced graphene oxide (PPy/rGO) composite and its derived Nitrogen-doped carbon nano-sheets (NCs) as positive and negative electrode material, respectively. The homogeneous nano-sheet and mesoporous structure of PPy/rGO and NCs can facilitate rapid charge/ion migration and provide more active sites for ions adsorption/exchange to improve their electrochemical performance. Benefiting from high capacitance and good rate performance of PPy/rGO and NCs electrodes, the as-fabricated ASCs devices in a polyvinyl alcohol/LiCl gel electrolyte can realize a wide operational voltage of 1.6 V and deliver high energy density of 15.8 wh kg-1 (1.01 mWh cm-3) at 0.14 kW kg-1 (19.3 mW cm-3), which still remains 9.5 wh kg-1as power density increases to 6.56 kW kg-1, as well as excellent long-term cycling stability with about 88.7% capacitance retention after 10000 cycles. The remarkable performances suggest that the ASCs devices are promising for future energy storage applications.

  15. Effect of Annealing Temperature and Time on Microstructure and Mechanical Properties of Multilayered Steel Composite Sheets

    Science.gov (United States)

    Cao, R.; Yu, X.; Feng, Z.; Ojima, M.; Inoue, J.; Koseki, T.

    2016-12-01

    Multilayered composite steels consisting of alternating layers of martensitic phase and austenitic phase exhibit an excellent combination of strength and elongation compared with conventional advanced high-strength steels. The deformation processes underlying these properties are of considerable interest. In this article, microstructure, grain size, and phase are characterized by scanning electron microscopy (SEM) and electron backscattering diffraction. The hardness of each layer is analyzed by a microindentation hardness testing system. Finally, the deformation and failure processes in multilayered steel are investigated by in-situ SEM. The hardness results indicate that various hardening modes occur in the soft austenitic layer and the hard martensitic layer. In- situ SEM results combined with microstructure analysis and hardness results reveal that annealing temperature and annealing time have a significant impact on final microstructure, fracture behavior, strength, hardness, and ductility.

  16. Novel cellulose ester substrates for high performance flat-sheet thin-film composite (TFC) forward osmosis (FO) membranes

    KAUST Repository

    Ong, Rui Chin

    2015-01-01

    A novel hydrophilic cellulose ester with a high intrinsic water permeability and a water partition coefficient was discovered to construct membrane supports for flat-sheet thin film composite (TFC) forward osmosis (FO) membranes for water reuse and seawater desalination with high performance. The performance of TFC-FO membranes prepared from the hydrophilic cellulose ester containing a high degree of OH and a moderate degree of Pr substitutions clearly surpasses those prepared from cellulose esters and other polymers with moderate hydrophilicity. Post-treatments of TFC-FO membranes using sodium dodecyl sulfate (SDS) and glycerol followed by heat treatment further enhance the water flux without compromising the selectivity. Positron annihilation lifetime analyses have confirmed that the SDS/glycerol post-treatment increases the free volume size and fractional free volume of the polyamide selective layer. The newly developed post-treated TFC-FO membranes exhibit a remarkably high water flux up to 90 LMH when the selective layer is oriented towards the draw solution (i.e., PRO mode) using 1. M NaCl as the draw solution and DI water as the feed. For seawater desalination, the membranes display a high water flux up to 35 LMH using a 2. M NaCl draw solution. These water fluxes exceeded the water fluxes achieved by other types of FO membranes reported in literatures. © 2014 Elsevier B.V.

  17. Continuous monitoring of summer surface water vapor isotopic composition above the Greenland Ice Sheet

    Directory of Open Access Journals (Sweden)

    H. C. Steen-Larsen

    2013-05-01

    Full Text Available We present here surface water vapor isotopic measurements conducted from June to August 2010 at the NEEM (North Greenland Eemian Drilling Project camp, NW Greenland (77.45° N, 51.05° W, 2484 m a.s.l.. Measurements were conducted at 9 different heights from 0.1 m to 13.5 m above the snow surface using two different types of cavity-enhanced near-infrared absorption spectroscopy analyzers. For each instrument specific protocols were developed for calibration and drift corrections. The inter-comparison of corrected results from different instruments reveals excellent reproducibility, stability, and precision with a standard deviations of ~ 0.23‰ for δ18O and ~ 1.4‰ for δD. Diurnal and intraseasonal variations show strong relationships between changes in local surface humidity and water vapor isotopic composition, and with local and synoptic weather conditions. This variability probably results from the interplay between local moisture fluxes, linked with firn–air exchanges, boundary layer dynamics, and large-scale moisture advection. Particularly remarkable are several episodes characterized by high (> 40‰ surface water vapor deuterium excess. Air mass back-trajectory calculations from atmospheric analyses and water tagging in the LMDZiso (Laboratory of Meteorology Dynamics Zoom-isotopic atmospheric model reveal that these events are associated with predominant Arctic air mass origin. The analysis suggests that high deuterium excess levels are a result of strong kinetic fractionation during evaporation at the sea-ice margin.

  18. Novel quantum dot and nano-sheet TiO2 (B) composite for enhanced photocatalytic H2 - Production without Co-Catalyst

    Science.gov (United States)

    Si, Jingjing; Wang, Yu; Xia, Xiaohong; Peng, Shuai; Wang, Ying; Xiao, Shuying; Zhu, Lingbin; Bao, Yuwen; Huang, Zhongbing; Gao, Yun

    2017-08-01

    Recently, the production of hydrogen through water splitting using titania (TiO2) as photocatalyst has received great attention in the new energy field. In this work, a single one-step hydrothermal method is used to synthesize ultra-thin TiO2 (B) nano-sheets, anatase TiO2, and their composite, using ethylene glycol (EG) and ethanol as the solvent. A new composite nanostructure with anatase TiO2 quantum dots grown on TiO2 (B) nano-sheets is obtained at certain ratios between EG and ethanol. Even without the help of co-catalyst, a high photocatalytic efficiency, about 45 times of that of rutile-anatase mixed Degussa P25, is observed in the TiO2 (B)-anatase composite nanostructure. The outstanding performance can be attributed to its large specific surface area, abundant surface active sites, mixed phase promoted efficient charge separation. Moreover, the properly aligned band structure, with the conduction band level of ultra-thin TiO2 (B) about 0.6 eV higher than that of the anatase, provides a large driving force for the reduction of water.

  19. 小茴香秸秆组分分析及薄片生产工艺%Fennel stalk composition analysis and the sheet production process

    Institute of Scientific and Technical Information of China (English)

    陈务平; 齐亚楠; 李金苗; 施娜

    2015-01-01

    Through the analysis and research of the main chemical composition, the fiber characteristics of fennel stalk were detected and analyzed. The results show that production of fennel straw sheet by pulping and papermaking process can replace traditional tobacco sheet for cigarette tobacco shred, which has low production cost and high additional value, can reduce the content of tar and nicotine in the tobacco sheet, with reaching the purposes of tar reduction and harm diminishment.%通过对小茴香秸秆主要化学成分的分析和研究,对其纤维特性进行了检测与分析。采用制浆造纸工艺方法生产小茴香秸秆薄片,替代传统的烟草薄片用于卷烟的烟丝制作,具有生产成本低和产品附加值高的特点,同时可以降低烟草薄片中的焦油含量和尼古丁含量,起到降焦减害的目的。

  20. Effects of annealing on the structure and magnetic properties of Fe–Si–Cr flakes and composite sheets

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Pyungwoo, E-mail: pwjang@cju.ac.kr [College of Science and Engineering, Cheongju University, Cheongju 360-764 (Korea, Republic of); Moon, Sujin [College of Science and Engineering, Cheongju University, Cheongju 360-764 (Korea, Republic of); Han, Dongwoo; Lee, Kyungsub [Changsung Corp., Pyeongtaek 451-831 (Korea, Republic of)

    2015-03-01

    Gas atomized Fe–Si–Cr powder was used in the application of a bypass sheet in near field communication. The powder was ball-milled, annealed at different temperatures and then manufactured to the sheet. Changes in microstructure and magnetic properties were investigated by XRD, VSM and an impedance analyzer. The as-milled Fe–Si–Cr flake consisted mainly of disordered A2 and ordered B2 phases while the atomized powder consisted of A2, B2 and DO{sub 3} phases. Increases in the annealing temperature caused the formation of a DO{sub 3} phase. At temperatures higher than 923 K, the final flake consisted of only A2 and DO{sub 3} phases. Grain size increased abruptly from 823 K, while the size of the DO{sub 3} phase increased rapidly from 623 K. Coercivity of the flake decreased after annealing, with the lowest coercivity obtained after 923 K annealing while saturation magnetization showed a minimum value of 928 kA/m after 523 K annealing. Sputtered Fe–12%Si films showed a highest electrical resistivity value of 191 μΩ·cm after 623 K annealing while the resistivity of Fe–4%Si sputtered films decreased almost linearly with annealing temperature. Therefore it could be concluded that high permeability of the 623 K sheet at 13.56 MHz and low permeability of the 923 K sheet at 80 MHz were due to the high resistivity as well as nanostructure of the 623 K flake. - Highlights: • Phase analysis in the atomized, milled and annealed powder by XRD. • Relationship between permeability and microstructure. • Variation of resistivity of Fe–Si films with annealing temperature.

  1. 农业废弃物纤维/废旧塑料制备复合板材的研制%Development of agricultural waste fiber/waste plastic composite sheet

    Institute of Scientific and Technical Information of China (English)

    闫晗

    2011-01-01

    Agricultural waste fiber/waste plastic composite sheet was prepared by use of pretreatment of wood flour, rice bran and straw with recycle plastic (mainly HDPE). The affects of different processing methods on mechanical properties of composite sheet were investigated. The results showed that mechanical peeling treatment of agricultural waste can improve the mechanical properties of composite sheet; wood flour improves the tensile properties of the composite sheet,and the contribution effect of straw on the impact strength of composite sheet is obvious.%利用木粉、稻糠、秸秆等农业废弃物天然纤维与废旧塑料(主体为HDPE)制备复合板材,研究了不同机械处理方法对复合板材力学性能的影响.结果表明,机械剥离处理的农业废弃物能有效提高复合板材的力学性能;木粉对复合板材拉伸性能的提高作用明显,而秸秆对复合板材的冲击强度贡献明显.

  2. A new consideration on reinforcement distribution in the different planes of nanostructured metal matrix composite sheets prepared by accumulative roll bonding (ARB)

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, Ali [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Blvd., 7134851154 Shiraz (Iran, Islamic Republic of); Salahinejad, E., E-mail: erfan.salahinejad@gmail.com [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Blvd., 7134851154 Shiraz (Iran, Islamic Republic of); Moradgholi, J.; Hosseini, M. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Blvd., 7134851154 Shiraz (Iran, Islamic Republic of)

    2011-09-29

    Highlights: > Al-B{sub 4}C composites can be successfully prepared by accumulative roll bonding (ARB). > TEM reveals the development of nanostructures in Al-B{sub 4}C composites processed by ARB. > The reinforcement distribution in the RD-ND planes is more uniform than the TD-ND planes. - Abstract: Recently, a number of novel methods based on accumulative roll bonding (ARB) have been introduced to produce particulate metal matrix composites. Nonetheless, the microstructure uniformity from the reinforcement distribution viewpoint in the different planes of ARBed composite sheets has not been focused up to date. This paper aims to compare the evolution of the B{sub 4}C particles distribution in nanostructured Al-10 vol.% B{sub 4}C composites prepared by ARB in the rolling direction-normal direction (RD-ND) and transverse direction-normal direction (TD-ND) planes. From optical microscopic evaluations quantified by the radial distribution function analysis, it is realized that the homogeneity in the RD-ND planes is in excess of the TD-ND planes. In addition, transmission electron microscopy reveals the development of nanostructures in the Al matrix after seven ARB passes.

  3. Microstructure and mechanical properties of twin-wire arc sprayed Ni-Al composite coatings on 6061-T6 aluminum alloy sheet

    Institute of Scientific and Technical Information of China (English)

    Ji-xiao Wang; Jing-shun Liu; Lun-yong Zhang; Jian-fei Sun; Zhi-ping Wang

    2014-01-01

    We have systematically studied the microstructure and mechanical properties of Ni-5wt%Al and Ni-20wt%Al composite coat-ings fabricated on 6061-T6 aluminum alloy sheet by twin-wire arc spraying under different experimental conditions. The abrasive wear be-havior and interface diffusion behavior of the composite coatings were evaluated by dry/wet rubber wheel abrasive wear tests and heat treat-ment, respectively. Experimental results indicate that the composite coatings exhibit features of adhesive wear. Besides, the Vickers micro-hardness of NiAl and Ni3Al intermetallic compounds is relatively larger than that of the substrate, which is beneficial for enhancing the wear resistance. With the increase of annealing temperature and time, the interface diffusion area between the Ni-Al coating and the substrate gradually expands with the formation of NiAl3 and Ni2Al3 phases, and is controlled by diffusion of aluminum atoms. The grain growth ex-ponent n of diffusion kinetics of the Ni-Al coating, calculated via a high-temperature diffusion model at 400, 480, and 550°C, is between 0.28 and 0.38. This satisfies the cubic law, which is consistent with the general theoretical relationship of high-temperature diffusion.

  4. Fact Sheets

    Science.gov (United States)

    ... Fact Sheets are available in both English and Spanish and can be downloaded for free. Currently available ... Antiviral Medications to Treat or Prevent Influenza (the Flu) PDF | Espanol PDF Apremilast (Otezla®) PDF | Espanol PDF ...

  5. High load-bearing multi-material-joints of metal sheets and composites by incremental in-situ forming processes

    Science.gov (United States)

    Seidlitz, Holger; Fritzsche, Sebastian; Bambach, Markus; Gerstenberger, Colin

    2016-10-01

    Thermo-mechanically flow-formed joints (FDJ) are an appropriate joining technology to realize high load-bearing multi-material-joints between fiber reinforced thermoplastics and sheet metals, without additional joining components. As in the automotive industry new vehicle and lightweight designs with one-sided accessibility joints are required, the technology which so far requires a two-sided accessibility of the joint, is examined for the ability to be performed with one-sided accessibility. The main part of the paper are therefore experimental studies on the one-sided manufacturing of FDJ-joints without an additional forming tool and their examination with head pull test and tension shear test according to DIN EN ISO 14272 and DIN EN ISO 14273. In this context, a tool and an experimental setup were designed to provide a corresponding joint production of a material combination of continuous glass fiber reinforced polypropylene (Plytron) and an aluminum alloy (EN AW-6082 T6). In the experiment, the novel joints bear maximum forces of 291 N in the head pull test and 708 N in the tension shear test.

  6. Towards free-standing graphene/carbon nanotube composite films via acetylene-assisted thermolysis of organocobalt functionalized graphene sheets.

    Science.gov (United States)

    Su, Qi; Liang, Yanyu; Feng, Xinliang; Müllen, Klaus

    2010-11-21

    A novel approach towards highly conductive free-standing chemically reduced graphene/carbon nanotube composite films via an in situ thermolysis of functionalized graphene/organic cobalt complexes was developed. By combining 1D-CNT and 2D-graphene, a synergistic effect of conductivity was established.

  7. Flexural strengthening of reinforced concrete beams with carbon fibers reinforced polymer (CFRP sheet bonded to a transition layer of high performance cement-based composite

    Directory of Open Access Journals (Sweden)

    V. J. Ferrari

    Full Text Available Resistance to corrosion, high tensile strength, low weight, easiness and rapidity of application, are characteristics that have contributed to the spread of the strengthening technique characterized by bonding of carbon fibers reinforced polymer (CFRP. This research aimed to develop an innovate strengthening method for RC beams, based on a high performance cement-based composite of steel fibers (macro + microfibers to be applied as a transition layer. The purpose of this transition layer is better control the cracking of concrete and detain or even avoid premature debonding of strengthening. A preliminary study in short beams molded with steel fibers and strengthened with CFRP sheet, was carried out where was verified that the conception of the transition layer is valid. Tests were developed to get a cement-based composite with adequate characteristics to constitute the layer transition. Results showed the possibility to develop a high performance material with a pseudo strain-hardening behavior, high strength and fracture toughness. The application of the strengthening on the transition layer surface had significantly to improve the performance levels of the strengthened beam. It summary, it was proven the efficiency of the new strengthening technique, and much information can be used as criteria of projects for repaired and strengthened structures.

  8. A Monetary Analysis of Balance Sheet Policies

    OpenAIRE

    2013-01-01

    We augment a standard macroeconomic model to analyze the effects and limitations of balance sheet policies. We show that the central bank can stimulate real activity by changing the size or the composition of its balance sheet, when interest rate policy is ineffective. Specifically, the central bank can stabilize the economy by increasing money supply against eligible assets even when the policy rate is at the zero lower bound. By changing the composition of its balance sheet, it can affect i...

  9. Fabrication of conducting composite sheets using cost-effective graphite flakes and amorphous styrene acrylonitrile for enhanced thermistor, dielectric, and electromagnetic interference shielding properties

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, Varij, E-mail: varijpanwarcertain@gmail.com [Electronics and Communication Engineering, Graphic Era University, Dehradun, Uttarakhand (India); Gill, Fateh Singh; Rathi, Vikas; Tewari, V.K. [Electronics and Communication Engineering, Graphic Era University, Dehradun, Uttarakhand (India); Mehra, R.M. [Sharda University, Greater Noida (India); Park, Jong-Oh, E-mail: jop@jnu.ac.kr [School of Mechanical Engineering, Chonnam National University, Gwangju (Korea, Republic of); Park, Sukho, E-mail: shpark12@dgist.ac.kr [Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology, Daegu (Korea, Republic of)

    2017-06-01

    The fabrication of strong conducting composite sheets (CCSs) using a simple technique with cost-effective materials is desirable for capacitor, decoupling capacitor, and electromagnetic interference (EMI) shielding applications. Here, we used cost-effective graphite flakes (GFs) as a conducting filler and amorphous poly (styrene-co-acrylonitrile) (PSAN) as an insulating polymer to fabricate a CCS via a simple mechanical mixing and hot compression molding process in 2.5 h, with the aim to save time and avoid the use of toxic reagents, which are generally used in chemical methods. In the present method, the GFs are connected in diffusively adhere polymer matrix, controlled by temperature and pressure that generate the conduction in the CCSs. The resulting PSAN/GF CCSs were characterized by using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and hardness tests. The GFs penetrated the interfacial region of PSAN, thus improving the thermistor and dielectric properties (dielectric constant, AC conductivity, and dissipation factor) of the PSAN/GF CCSs. Furthermore, the PSAN/GF CCSs showed enhanced hardness and EMI shielding effectiveness (SE) properties in the X-band frequency range (8.5–12.5 GHz). The percolation theory was implemented to DC and AC conductivity. To detect the transition of the dielectric properties, the dielectric constant of the CCSs was analyzed with increasing volume fraction of GFs in the radio frequency region. The improved dielectric constant, AC conductivity, and dissipation factor of the PSAN/GF CCS, indicated a significant improvement in their EMI shielding properties in the X-band frequency range, which were measured using the waveguide method. The ac conductivity of PSAN/GF CCS shows stable behavior in the higher frequency ranges. The EMISE of PSAN/GF CCS were found to increase with increasing GF content due to the absorbance mechanism. - Highlights: • Enhanced hardness and

  10. Investigation of the impact of simulated solar radiation on the micro- and nanoscale morphology and mechanical properties of a sheet moulded composite surface

    Directory of Open Access Journals (Sweden)

    Sikora Andrzej

    2016-09-01

    Full Text Available In this paper we present the results of investigation of micro- and nanoscale degradation of a sheet moulded composite exposed to simulated solar radiation. Utilization of high resolution methods such as atomic force microscopy, optical profilometry and microcomputer tomography allowed us to provide the evidence of significant deterioration of the surface as well as the material few microns in depth. Additionally, the typically used macroscopic investigations, such as wettability and flexural strength, were performed to observe the impact of weathering process. It was also shown that high resolution techniques provide superior sensitivity of the material degradation detection. The particular effectiveness of the applied approach was related to the structure of investigated material, as due to its degradation, a number of voids appeared, causing a significant roughness increase. In addition, the impact of light radiation could be compared to other environmental conditions maintained in the climatic chamber. It should be underlined, that according to our knowledge, such a study has not been performed so far.

  11. Development of a novel composite material with carbon nanotubes assisted by self-assembled peptides designed in conjunction with β-sheet formation.

    Science.gov (United States)

    Hashida, Yasuhiko; Umeyama, Tomokazu; Mihara, Junya; Imahori, Hiroshi; Tsujimoto, Masahiko; Isoda, Seiji; Takano, Mikio; Hashida, Mitsuru

    2012-09-01

    A novel composite material is developed with single-walled carbon nanotubes (SWCNTs) and artificially designed peptides, and its chemical and physicochemical characteristics are evaluated with an aim toward biomedical application. The peptides were designed to form a β-sheet structure that would be suitable for wrapping SWCNTs. The complex of SWCNTs and peptide (SWCNT-peptide) showed good dispersibility in aqueous media and was considerably stable even in the absence of an excess amount of peptide in the media. The formation of SWCNT-peptide was confirmed by its performance in water, atomic force microscopy and transmission electron microscopy observation, and molecular modeling. The possibility of introducing various functions to SWCNT-peptide was also demonstrated by several methods, such as introduction of special amino acids, chemical modification, and additional complex formation based on electrostatic interaction. These results suggest the potential of the SWCNT-peptide complex as a molecular platform on which a desirable structure and/or function can be constructed for biomedical and industrial application.

  12. Quality Analysis and Improvement Methods of Surface of Multi-layered Rubber Composite Sheet%多层橡胶片材层叠复合表面压延质量分析及改善措施

    Institute of Scientific and Technical Information of China (English)

    秦柳; 丁玉梅; 杨卫民

    2013-01-01

    Based on the lamination principle of multi-layered rubber composite sheet,the root causes for unevenness, non-uniform, wrinkle and ripple on the surface of the composite sheet were analyzed, and the improvement methods were proposed. By precisely controlling calendering process,setting the roller temperature at 100 ℃ and the speed at 24 m · min-1 ,the surface quality of the calendered composite sheet was improved.%根据多层橡胶片材层叠复合的原理,分析采用压延工艺制备出的复合片材表面出现不平整、不均匀,产生皱纹、鱼鳞纹的现象,提出相应的解决措施.试验得出,压延机辊筒温度为100℃、辊速为24 m·min-1时,压延的复合片材表面质量较好.

  13. Composite biaxially textured substrates using ultrasonic consolidation

    Science.gov (United States)

    Blue, Craig A; Goyal, Amit

    2013-04-23

    A method of forming a composite sheet includes disposing an untextured metal or alloy first sheet in contact with a second sheet in an aligned opposing position; bonding the first sheet to the second sheet by applying an oscillating ultrasonic force to at least one of the first sheet and the second sheet to form an untextured intermediate composite sheet; and annealing the untextured intermediate composite sheet at a temperature lower than a primary re-crystallization temperature of the second sheet and higher than a primary re-crystallization temperature of the first sheet to convert the untextured first sheet into a cube textured sheet, wherein the cube texture is characterized by a .phi.-scan having a FWHM of no more than 15.degree. in all directions, the second sheet remaining untextured, to form a composite sheet.

  14. Structural Biology Fact Sheet

    Science.gov (United States)

    ... Home > Science Education > Structural Biology Fact Sheet Structural Biology Fact Sheet Tagline (Optional) Middle/Main Content Area ​Other Fact Sheets What is structural biology? Structural biology is the study of how biological ...

  15. Integrated effect of supramolecular self-assembled sandwich-like melamine cyanurate/MoS{sub 2} hybrid sheets on reducing fire hazards of polyamide 6 composites

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiaming [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Wang, Xin, E-mail: wxcmx@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Cai, Wei; Hong, Ningning [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Liew, Kim Meow [Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Suzhou, Jiangsu 215123 (China); Department of Architectural and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2016-12-15

    A novel strategy of using supramolecular self-assembly for preparing sandwich-like melamine cyanurate/MoS{sub 2} sheets as the hybrid flame retardants for polyamide 6 (PA6) is reported for the first time. The introduction of MoS{sub 2} sheets function not only as a template to induce the formation of two-dimensional melamine cyanurate capping layers but also as a synergist to generate integrated flame-retarding effect of hybrid sheets, as well as a high-performance smoke suppressor to reduce fire hazards of PA6 materials. Once incorporating this well-designed structures (4 wt%) into PA6 matrix, there resulted in a remarkable drop (40%) in the peak heat release rate and a 25% reduction in total heat release. Moreover, the smoke production and pyrolysis gaseous products were efficiently suppressed by the addition of sandwich-like hybrid sheets. The integrated functions consisting of inherent flame retarding effect, physical barrier performance and catalytic activity are believed to the crucial guarantee for the reduced fire hazards of PA6 nanocomposites. Furthermore, this novel strategy with facile and scalable features may provide reference for developing various kinds of MoS{sub 2} based hybrid sheets for diverse applications.

  16. Method for the preparation of cellulose acetate flat sheet composite membranes for forward osmosis—Desalination using MgSO4 draw solution

    KAUST Repository

    Sairam, M.

    2011-06-01

    A lab scale method for the preparation of defect free flat sheet composite membranes for forward osmosis (FO) has been developed. Membranes containing a thin layer of cellulose acetate (CA) cast on a nylon fabric of 50μm thick were prepared by phase inversion in water. Cellulose acetate (CA) membranes with an overall thickness of 70-80μm have been prepared with lactic acid, maleic acid and zinc chloride as pore forming agents, at different annealing temperatures, for forward osmosis. These membranes have been tested in the desalination of saline feeds (35g·L-1 of NaCl) using magnesium sulphate solution (150g·L-1) as the draw solution. The water flux, and rejection of NaCl, were compared with those of commercially available membranes tested under the same FO conditions. The commercially available FO membrane from Hydration Technologies Inc, OR (M1) has a permeability of 0.13L·h-1·m-2·bar-1 with a NaCl rejection of 97% when tested with 150g·L-1 of MgSO4 in the draw solution. Another commercially available membrane for FO from Hydration Technologies Inc, OR, M2 has a water permeability of 0.014L·h-1·m-2·bar-1 with NaCl rejection of 100%. The flux and rejection of the CA membranes prepared in this work are found to be dependent on the nature of the pore forming agent, and annealing temperature. Impregnation of an inorganic filler, sodium montmorrillonite in CA membranes and coating of CA membranes with hydrophilic PVA did not enhance the flux of base CA membranes. Cellulose acetate membranes cast from dope solutions containing acetone/isopropanol and lactic acid, maleic acid and zinc chloride as pore forming agents have water permeabilities of 0.13, 0.09 and 0.68L·h-1·m-2·bar-1 respectively, with NaCl rejections of 97.7, 99.3 and 88% when annealed at 50°C. CA membranes prepared with zinc chloride as a pore forming agent have good permeability of 0.27L·h-1·m-2·bar-1 with a NaCl rejection of 95% when annealed at 70°C. © 2011.

  17. Tantalum Sheet for Superconductor Diffusion Barrier Applications

    Science.gov (United States)

    Mathaudhu, S. N.; Hartwig, K. T.; Barber, R. E.; Pyon, T.

    2006-03-01

    This report presents preliminary results of a project with the aim to fabricate fine-grained tantalum sheet having a uniform microstructure that co-deforms well with pure copper for superconductor diffusion barrier applications. Multi-pass equal channel angular extrusion (ECAE) was used to refine the microstructure of 25 mm square cross-section bars of Ta; rolling was used to convert the bars to 0.38 mm thick sheet. Cu-Ta co-deformation characteristics were evaluated by assembling and drawing experimental Cu-Ta composite wires, containing the ECAE processed sheets, to 0.83 mm diameter and metallographically examining the thinned 2-4 micron Ta layer. The ECAE processed Ta sheet co-deformed well with Cu, and was found to have a smaller recrystallized grain size, a narrower grain size distribution and a slightly higher hardness compared to commercial diffusion barrier grade Ta sheet. The favorable results encourage further work.

  18. Zika Virus Fact Sheet

    Science.gov (United States)

    ... sheets Fact files Questions & answers Features Multimedia Contacts Zika virus Fact sheet Updated 6 September 2016 Key ... and last for 2-7 days. Complications of Zika virus disease Based on a systematic review of ...

  19. Trauma Fact Sheet

    Science.gov (United States)

    ... Home > Science Education > Physical Trauma Fact Sheet Physical Trauma Fact Sheet Tagline (Optional) Middle/Main Content Area ... of physical trauma. Credit: iStock. What is physical trauma? Physical trauma is a serious injury to the ...

  20. Diabetes Fact Sheet

    Science.gov (United States)

    ... diabetes by losing weight. Related information Fitness and nutrition Heart disease and stroke Obesity and weight loss fact sheet Physical activity fact sheet Pregnancy The javascript used in this widget is not ...

  1. How Will Sea Ice Loss Affect the Greenland Ice Sheet? On the Puzzling Features of Greenland Ice-Core Isotopic Composition

    Science.gov (United States)

    Pausata, Francesco S. R.; Legrande, Allegra N.; Roberts, William H. G.

    2016-01-01

    The modern cryosphere, Earth's frozen water regime, is in fast transition. Greenland ice cores show how fast theses changes can be, presenting evidence of up to 15 C warming events over timescales of less than a decade. These events, called Dansgaard/Oeschger (D/O) events, are believed to be associated with rapid changes in Arctic sea ice, although the underlying mechanisms are still unclear. The modern demise of Arctic sea ice may, in turn, instigate abrupt changes on the Greenland Ice Sheet. The Arctic Sea Ice and Greenland Ice Sheet Sensitivity (Ice2Ice Chttps://ice2ice.b.uib.noD) initiative, sponsored by the European Research Council, seeks to quantify these past rapid changes to improve our understanding of what the future may hold for the Arctic. Twenty scientists gathered in Copenhagen as part of this initiative to discuss the most recent observational, technological, and model developments toward quantifying the mechanisms behind past climate changes in Greenland. Much of the discussion focused on the causes behind the changes in stable water isotopes recorded in ice cores. The participants discussed sources of variability for stable water isotopes and framed ways that new studies could improve understanding of modern climate. The participants also discussed how climate models could provide insights into the relative roles of local and nonlocal processes in affecting stable water isotopes within the Greenland Ice Sheet. Presentations of modeling results showed how a change in the source or seasonality of precipitation could occur not only between glacial and modern climates but also between abrupt events. Recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. Further, indications from recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. This feature complicates

  2. Thermomechanical processing of plasma sprayed intermetallic sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  3. Flexible Structural-Health-Monitoring Sheets

    Science.gov (United States)

    Qing, Xinlin; Kuo, Fuo

    2008-01-01

    A generic design for a type of flexible structural-health-monitoring sheet with multiple sensor/actuator types and a method of manufacturing such sheets has been developed. A sheet of this type contains an array of sensing and/or actuation elements, associated wires, and any other associated circuit elements incorporated into various flexible layers on a thin, flexible substrate. The sheet can be affixed to a structure so that the array of sensing and/or actuation elements can be used to analyze the structure in accordance with structural-health-monitoring techniques. Alternatively, the sheet can be designed to be incorporated into the body of the structure, especially if the structure is made of a composite material. Customarily, structural-health monitoring is accomplished by use of sensors and actuators arrayed at various locations on a structure. In contrast, a sheet of the present type can contain an entire sensor/actuator array, making it unnecessary to install each sensor and actuator individually on or in a structure. Sensors of different types such as piezoelectric and fiber-optic can be embedded in the sheet to form a hybrid sensor network. Similarly, the traces for electric communication can be deposited on one or two layers as required, and an entirely separate layer can be employed to shield the sensor elements and traces.

  4. Sulfide composition and microthermometry of fluid inclusions in the leg 111 sheeted dike section of Ocean Drilling Program hole 504B, Costa Rica rift

    Energy Technology Data Exchange (ETDEWEB)

    Schoeps, D. (Technische Hochschule Aachen (West Germany)); Herzig, P.M. (Univ. of Toronto, Ontario (Canada))

    1990-06-10

    Hole 504B of the Ocean Drilling Program is dedicated to the study of crustal structure and hydrothermal processes in 5.9-m.y.-old oceanic basement. Continuing the work of previous legs, hole 504B was extended 212.3 m to a total depth of 1,562.3 m below seafloor (bsf) during leg 111 in 1986. Quartz-sulfide veins occur at a depth of 1,369-1,388 m bsf in basalts of the sheeted dike complex. The ore minerals are predominantly pyrite, less chalcopyrite, rare Co-rich Cu-Fe-S phases, and a thiospinel (linnaeite/carrollite). Microprobe analyses yield a high Co content in zoned vein pyrites (>8 wt%) as well as in the Cu-Fe-S phases (>5 wt%). Up to 35.8 wt% CO was detected in the thiospinel. A Co/Ni ratio of > 100 distinguishes the vein pyrite from pyrite in the basaltic wall rock and from pyrite formed as an alteration product of olivine (Co/Ni < 5). The Co/Ni ratios correlate positively with Cu and negatively with As. Co-rich, nonstoichiometric Cu-Fe-S sulfides in chalcopyrite are interpreted as metastable phases which have been quenched at a high temperature and prohibited from exsolution of the stable products chalcopyrite and pyrite. Fluid inclusions in quartz from the quartz-sulfide veins are two-phase and vary from liquid- to vapor-dominated. Their salinities range from 4.2 to 7.2 wt% equivalent NaCl and average 5.5 wt%. Pressure (360 bars) corrected average filling temperatures vary from 271 to 408 C with a maximum of 486 C. This is consistent with calculated quartz formation temperatures for a single quartz separate (+4.2{per thousand} {delta}{sup 18}O) using oxygen isotope thermometry. The {delta}{sup 18}O value of the hydrothermal fluid was determined to be +1.7{per thousand}. The temperature data indicate fluid alteration of the sheeted dikes at about 350 to 500 C.

  5. Ice sheet in peril

    DEFF Research Database (Denmark)

    Hvidberg, Christine Schøtt

    2016-01-01

    Earth's large ice sheets in Greenland and Antarctica are major contributors to sea level change. At present, the Greenland Ice Sheet (see the photo) is losing mass in response to climate warming in Greenland (1), but the present changes also include a long-term response to past climate transitions....... On page 590 of this issue, MacGregor et al. (2) estimate the mean rates of snow accumulation and ice flow of the Greenland Ice Sheet over the past 9000 years based on an ice sheet-wide dated radar stratigraphy (3). They show that the present changes of the Greenland Ice Sheet are partly an ongoing...... response to the last deglaciation. The results help to clarify how sensitive the ice sheet is to climate changes....

  6. Ice sheet in peril

    DEFF Research Database (Denmark)

    Hvidberg, Christine Schøtt

    2016-01-01

    Earth's large ice sheets in Greenland and Antarctica are major contributors to sea level change. At present, the Greenland Ice Sheet (see the photo) is losing mass in response to climate warming in Greenland (1), but the present changes also include a long-term response to past climate transitions....... On page 590 of this issue, MacGregor et al. (2) estimate the mean rates of snow accumulation and ice flow of the Greenland Ice Sheet over the past 9000 years based on an ice sheet-wide dated radar stratigraphy (3). They show that the present changes of the Greenland Ice Sheet are partly an ongoing...... response to the last deglaciation. The results help to clarify how sensitive the ice sheet is to climate changes....

  7. A Study of Organic-Inorganic Composite Passivation Film for Galvanized Sheet%镀锌板有机-无机复合钝化膜的研究

    Institute of Scientific and Technical Information of China (English)

    徐丽萍; 胡丰; 杨兴亮; 陈均; 张千峰

    2012-01-01

    An organic-inorganic composite passivation film for galvanized sheets was prepared using water-based acrylic resin as main film forming agent, silane as auxiliary film forming agent, Na2MoO4 and NH4VO3 as inorganic inhibitors. The corrosion resistance, surface morphology and composition of the organic-inorganic composite passivation film were characterized and analyzed by polarization curves, electrochemical impedance spectroscopy, salt spray test, scanning electron microscopy and energy dispersive spectrum. The results show that the surface of the obtained organic-inorganic composite passivation film, smooth and uniform, can prevent O2 and H2O entry and inhibit cathode and anode corrosion, thus the polarization resistance and corrosion resistance of the zinc coating are improved.%以水性硅丙树脂为主成膜剂,以有机硅烷为辅助成膜剂,以钼酸钠和偏钒酸铵为无机缓蚀剂,在镀锌板表面制备了有机-无机复合钝化膜.通过极化曲线、电化学交流阻抗谱、盐雾实验、扫描电镜和能谱仪对钝化膜的耐蚀性、表面形貌及成分进行了表征与分析.结果表明:所得钝化膜表面平整、均匀,阻止了氧气和水分的进入,抑制了阴、阳极腐蚀,提高了镀锌层的极化电阻及耐蚀性.

  8. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  9. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2010-01-01

    New Year is an open composition to be realised by improvising musicians. It is included in "From the Danish Seasons" (see under this title). See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You...

  10. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  11. Thermoforming of foam sheet

    NARCIS (Netherlands)

    Akkerman, Remko; Pronk, Ruud M.

    1997-01-01

    Thermoforming is a widely used process for the manufacture of foam sheet products. Polystyrene foam food trays for instance can be produced by first heating the thermoplastic foam sheet, causing the gas contained to build up pressure and expand, after which a vacuum pressure can be applied to draw t

  12. Mechanics of Sheeting Joints

    Science.gov (United States)

    Martel, S. J.

    2015-12-01

    Physical breakdown of rock across a broad scale spectrum involves fracturing. In many areas large fractures develop near the topographic surface, with sheeting joints being among the most impressive. Sheeting joints share many geometric, textural, and kinematic features with other joints (opening-mode fractures) but differ in that they are (a) discernibly curved, (b) open near the topographic surface, and (c) form subparallel to the topographic surface. Where sheeting joints are geologically young, the surface-parallel compressive stresses are typically several MPa or greater. Sheeting joints are best developed beneath domes, ridges, and saddles; they also are reported, albeit rarely, beneath valleys or bowls. A mechanism that accounts for all these associations has been sought for more than a century: neither erosion of overburden nor high lateral compressive stresses alone suffices. Sheeting joints are not accounted for by Mohr-Coulomb shear failure criteria. Principles of linear elastic fracture mechanics, together with the mechanical effect of a curved topographic surface, do provide a basis for understanding sheeting joint growth and the pattern sheeting joints form. Compressive stresses parallel to a singly or doubly convex topographic surface induce a tensile stress perpendicular to the surface at shallow depths; in some cases this alone could overcome the weight of overburden to open sheeting joints. If regional horizontal compressive stresses, augmented by thermal stresses, are an order of magnitude or so greater than a characteristic vertical stress that scales with topographic amplitude, then topographic stress perturbations can cause sheeting joints to open near the top of a ridge. This topographic effect can be augmented by pressure within sheeting joints arising from water, ice, or salt. Water pressure could be particularly important in helping drive sheeting joints downslope beneath valleys. Once sheeting joints have formed, the rock sheets between

  13. Cell sheet engineering

    Directory of Open Access Journals (Sweden)

    Masayuki Yamato

    2004-05-01

    Full Text Available We have developed ‘cell sheet engineering’ in order to avoid the limitations of tissue reconstruction using biodegradable scaffolds or single cell suspension injection. Our concept is tissue reconstruction, not from single cells, but from cell sheets. Cell sheets are prepared using temperature-responsive culture dishes. Temperature-responsive polymers are covalently grafted onto the dishes, allowing various types of cells to adhere and proliferate at 37°C. The cells spontaneously detach when the temperature is reduced below 32°C without the need for proteolytic enzymes. The confluent cells are noninvasively harvested as single, contiguous cell sheets with intact cell-cell junctions and deposited extracellular matrix (ECM. We have used these harvested cell sheets for various tissue reconstructions, including ocular surfaces, periodontal ligaments, cardiac patches, and bladder augmentation.

  14. Precisely Assembled Nanofiber Arrays as a Platform to Engineer Aligned Cell Sheets for Biofabrication

    Directory of Open Access Journals (Sweden)

    Vince Beachley

    2014-08-01

    Full Text Available A hybrid cell sheet engineering approach was developed using ultra-thin nanofiber arrays to host the formation of composite nanofiber/cell sheets. It was found that confluent aligned cell sheets could grow on uniaxially-aligned and crisscrossed nanofiber arrays with extremely low fiber densities. The porosity of the nanofiber sheets was sufficient to allow aligned linear myotube formation from differentiated myoblasts on both sides of the nanofiber sheets, in spite of single-side cell seeding. The nanofiber content of the composite cell sheets is minimized to reduce the hindrance to cell migration, cell-cell contacts, mass transport, as well as the foreign body response or inflammatory response associated with the biomaterial. Even at extremely low densities, the nanofiber component significantly enhanced the stability and mechanical properties of the composite cell sheets. In addition, the aligned nanofiber arrays imparted excellent handling properties to the composite cell sheets, which allowed easy processing into more complex, thick 3D structures of higher hierarchy. Aligned nanofiber array-based composite cell sheet engineering combines several advantages of material-free cell sheet engineering and polymer scaffold-based cell sheet engineering; and it represents a new direction in aligned cell sheet engineering for a multitude of tissue engineering applications.

  15. Single sheet metal oxides and hydroxides

    DEFF Research Database (Denmark)

    Huang, Lizhi

    the possibility to gain precise control of the structure, composition, morphology, and property of desired nanostructures. In the present Ph.D. project, examples to produce 2D nanosheets with novel functionalities are presented. This comprises: (1) Synthesis of LDHs with a new structure and composition. (2......) Delamination of the LDHs structure (oxGRC12) with the formation of single sheet iron (hydr)oxide (SSI). (3) Assembly of the new 2D nanosheets layer by layer to achieve desired functionalities....

  16. Preparation of oriented graphite/polymer composite sheets with high thermal conductivities by tape casting%流延法制备高热导率定向石墨/高分子复合片层材料

    Institute of Scientific and Technical Information of China (English)

    周绍鑫; 祝渊; 杜鸿达; 李宝华; 康飞宇

    2012-01-01

    Oriented graphite/polymer composite sheets were prepared using natural,crystalline flake graphites as raw materials,polyvinyl butyral as binders,polyethylene glycol and dibutyl phthalate as plasticizers by a tape-casting method at room temperature.The dependences of the binder contents and the blade heights on the orientation of the composite sheets were studied,and the effect of the orientation on the thermal conductivity was investigated.X-ray diffraction patterns and scanning electron microscope images showed that as-prepared samples showed different degrees of orientation.The thermal conductivity increased with the degree of orientation.The highest thermal conductivity of 490 W/( m· K) could be achieved by optimizing the binder contents and the blade heights.%以天然鳞片石墨为原料,PVB为黏结剂,PEG和DBP混合物为增塑剂,通过流延工艺在室温下制备了定向排列的石墨/聚合物片层复合材料.系统分析了不同黏结剂用量和流延刀口高度下复合片层材料的定向排列状况,并探讨了定向排列程度对其热导率的影响.XRD和SEM的结果表明,石墨/聚合物复合片层材料显示了不同程度的定向排列.热导率测试结果表明,片层复合材料的热导率随着定向排列程度的提高而增大.通过优化黏结剂的用量和流延刀口高度制备了具有较高热导率的片层复合材料,其热导率最高可达490 W/(m·K).

  17. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Science.gov (United States)

    Sreejesh, M.; Shenoy, Sulakshana; Sridharan, Kishore; Kufian, D.; Arof, A. K.; Nagaraja, H. S.

    2017-07-01

    Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM-1 cm-2 with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg-1 at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  18. «Acts of wisdom and trust»: Sheets, Tapes and Machines in Egisto Macchi’s Film Music Composition

    Directory of Open Access Journals (Sweden)

    Marco Cosci

    2015-08-01

    Full Text Available Egisto Macchi (1928-92 was a key figure in the renewal of late 20th century Italian musical life, as he contributed significantly to the creation of institutions such as Nuova Consonanza. During the 1960s his significant involvement in film production led him to compose scores for hundreds of short films, working with leading Italian documentary filmmakers, and for several feature films. The relationship between Macchi’s musical strategies and the film production apparatus has not hitherto received much scholarly attention. Drawing on archival sources, this essay aims at discussing the different compositional levels that are layered in Macchi’s soundtracks. The study of sketches and paratextual indications in the score allows a close look at the relation between musical ideas and their realizations from a perspective strongly influenced by film post-production technologies.

  19. High performance nano-titania photocatalytic paper composite. Part I: Experimental design study for TiO{sub 2} composite sheet using a natural zeolite microparticle system and its photocatalytic property

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Seonghyuk, E-mail: sko@ncat.ed [Department of Paper Engineering, Chemical Engineering and Imaging, Western Michigan University, Kalamazoo, MI 49008 (United States); Pekarovic, Jan; Fleming, Paul D. [Department of Paper Engineering, Chemical Engineering and Imaging, Western Michigan University, Kalamazoo, MI 49008 (United States); Ari-Gur, Pnina [Department of Mechanical and Aeronautical Engineering, Western Michigan University, Kalamazoo, MI 49008 (United States)

    2010-01-25

    Nanosized titanium dioxide (TiO{sub 2}) photocatalytic papers were successfully prepared using a natural zeolite microparticle retention aid in papermaking. Applying a factorial experimental design, natural zeolite has been demonstrated to be the most significant and interactive factor for increasing the TiO{sub 2} retention rate in paper stock. The photocatalysis of as-prepared sheets was evaluated with toluene as one of the representative volatile organic compounds (VOCs). Under UV irradiation, it was shown to be effective in removing gaseous toluene by photodecomposition, assisted by adsorption. It was revealed that natural zeolite plays an important role in both increasing retention rate of TiO{sub 2} nanoparticles and enhancing photocatalytic efficiency of the paper. The photocatalytic paper can be potentially applied for environmental purification.

  20. Algebra task & drill sheets

    CERN Document Server

    Reed, Nat

    2011-01-01

    For grades 6-8, our State Standards-based combined resource meets the algebraic concepts addressed by the NCTM standards and encourages the students to review the concepts in unique ways. The task sheets introduce the mathematical concepts to the students around a central problem taken from real-life experiences, while the drill sheets provide warm-up and timed practice questions for the students to strengthen their procedural proficiency skills. Included are opportunities for problem-solving, patterning, algebraic graphing, equations and determining averages. The combined task & drill sheets

  1. Algebra task & drill sheets

    CERN Document Server

    Reed, Nat

    2011-01-01

    For grades 3-5, our State Standards-based combined resource meets the algebraic concepts addressed by the NCTM standards and encourages the students to review the concepts in unique ways. The task sheets introduce the mathematical concepts to the students around a central problem taken from real-life experiences, while the drill sheets provide warm-up and timed practice questions for the students to strengthen their procedural proficiency skills. Included are opportunities for problem-solving, patterning, algebraic graphing, equations and determining averages. The combined task & drill sheets

  2. Study on Stress Concentrations in an Intraply Hybrid Composite Sheet%层内混杂复合材料应力集中问题的研究

    Institute of Scientific and Technical Information of China (English)

    曾庆敦; 黄小清; 林雪慧

    2001-01-01

    提出了一种合理、简便、精确的修正的剪滞模型,基于此模型,分析了受拉伸的层内混杂复合材料中某些纤维断裂后的应力重分布,结果表明,求得的应力集中因子与Fukuda和Chou的结果相当接近,从而证实了本文模型和方法的合理性和正确性,%A reasonably, simply and accurately modified shear_lag model was proposed. Based on the model, the stress redistributions due to the failure of some fibers in an intraply hybrid composite under tension were analyzed. The results show that the present calculating stress concentration factors very coincide with Fukuda and Chou's results, thus verifying the reasonableness and correctness of the present model and methods.

  3. Convert Graphene Sheets to Boron Nitride and Boron Nitride-Carbon Sheets via a Carbon-Substitution-Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Han, W.; Yu, H.-G.; Liu. Z.

    2011-05-16

    Here we discuss our synthesis of highly crystalline pure boron nitride (BN) and BN-carbon (BN-C) sheets by using graphene sheets as templates via a carbon-substitution reaction. Typically, these sheets are several micrometers wide and have a few layers. The composition ratios of BN-C sheets can be controlled by the post-treatment (remove carbon by oxidation) temperature. We also observed pure BN and BN-C nanoribbons. We characterized the BN-C sheets via Raman spectroscopy and density functional theory calculations. The results reveal that BN-C sheets with an armchair C-BN chain, and embedded C{sub 2} or C{sub 6} units in BN-dominated regions energetically are the most favorable.

  4. HRSA Data Fact Sheets

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Health Resources and Services Administration (HRSA) Data Fact Sheets provide summary data about HRSA’s activities in each Congressional District, County, State,...

  5. Pharmacogenomics Fact Sheet

    Science.gov (United States)

    ... incorporate genomic results into medical care. Other NIGMS Fact Sheets Related Links Up to top This page last reviewed on September 28, 2017 Social Media Links Bookmark & Share Free Subscriptions Twitter Facebook ...

  6. Respirator Fact Sheet

    Science.gov (United States)

    ... have expiration dates that should be checked before purchase. Also, over time your mask can get old ... Respirator Fact Sheet [PDF - 706 KB] Follow NIOSH Facebook Flickr Pinterest Twitter YouTube NIOSH Homepage NIOSH A- ...

  7. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  8. Energy information sheets

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-01

    The National Energy Information Center (NEIC), as part of its mission, provides energy information and referral assistance to Federal, State, and local governments, the academic community, business and industrial organizations, and the public. The Energy Information Sheets was developed to provide general information on various aspects of fuel production, prices, consumption, and capability. Additional information on related subject matter can be found in other Energy Information Administration (EIA) publications as referenced at the end of each sheet.

  9. 2013 social balance sheet

    OpenAIRE

    Pierrette Heuse

    2014-01-01

    The transposition into national law of Directive 2013/34/EU on the annual financial statements of companies, expected by no later than July 2015, could alter the statistical obligations on small firms in connection with the filing of their annual accounts. In any case, the social balance sheet can no longer form an integral part of their accounts. Nevertheless, it contains original information whose usefulness is highlighted, on the basis of the social balance sheets for 2012, by examining th...

  10. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all....... Please DOWNLOAD them to see/hear them in full length! This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute it, performance instructions as well as specially designated recordings, as long as the author is mentioned. Please see http...

  11. Safety advice sheets

    CERN Multimedia

    HSE Unit

    2013-01-01

    You never know when you might be faced with questions such as: when/how should I dispose of a gas canister? Where can I find an inspection report? How should I handle/store/dispose of a chemical substance…?   The SI section of the DGS/SEE Group is primarily responsible for safety inspections, evaluating the safety conditions of equipment items, premises and facilities. On top of this core task, it also regularly issues “Safety Advice Sheets” on various topics, designed to be of assistance to users but also to recall and reinforce safety rules and procedures. These clear and concise sheets, complete with illustrations, are easy to display in the appropriate areas. The following safety advice sheets have been issued so far: Other sheets will be published shortly. Suggestions are welcome and should be sent to the SI section of the DGS/SEE Group. Please send enquiries to general-safety-visits.service@cern.ch.

  12. Energy information sheets

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-02

    The National Energy Information Center (NEIC), as part of its mission, provides energy information and referral assistance to Federal, State, and local governments, the academic community, business and industrial organizations, and the general public. Written for the general public, the EIA publication Energy Information Sheets was developed to provide information on various aspects of fuel production, prices, consumption and capability. The information contained herein pertains to energy data as of December 1991. Additional information on related subject matter can be found in other EIA publications as referenced at the end of each sheet.

  13. Ice Sheets & Ice Cores

    DEFF Research Database (Denmark)

    Mikkelsen, Troels Bøgeholm

    Since the discovery of the Ice Ages it has been evident that Earth’s climate is liable to undergo dramatic changes. The previous climatic period known as the Last Glacial saw large oscillations in the extent of ice sheets covering the Northern hemisphere. Understanding these oscillations known...... as Dansgaard-Oeschger (DO) events would add to our knowledge of the climatic system and – hopefully – enable better forecasts. Likewise, to forecast possible future sea level rise it is crucial to correctly model the large ice sheets on Greenland and Antarctica. This project is divided into two parts...

  14. Non-oriented electrical sheets

    Science.gov (United States)

    Brissonneau, Pierre

    1984-02-01

    After placing the economic and technological importance of non-oriented magnetic sheets on the same level as that of grain-oriented sheets, the recent stages in the history of non-oriented sheets are recalled. The progress made in the knowledge of the physics of magnetism now allows the functions of the principal properties of non-oriented sheets to be analyzed. Current production of non-oriented sheets is marked by an evolution towards a split of the market between top-grade sheets, which could still be improved significantly, and lower grades, for which the cost of production continues to be practically the only determining factor.

  15. Ice-sheet configuration in the CMIP5/PMIP3 Last Glacial Maximum experiments

    Directory of Open Access Journals (Sweden)

    A. Abe-Ouchi

    2015-11-01

    stationary waves. Differences between the climate response to the CMIP5/PMIP3 composite and any individual ice-sheet reconstruction are smaller than those between the CMIP5/PMIP3 composite and the ice sheet used in the last phase of PMIP (PMIP2.

  16. Composites

    Science.gov (United States)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  17. Production (information sheets)

    NARCIS (Netherlands)

    2007-01-01

    Documentation sheets: Geo energy 2 Integrated System Approach Petroleum Production (ISAPP) The value of smartness 4 Reservoir permeability estimation from production data 6 Coupled modeling for reservoir application 8 Toward an integrated near-wellbore model 10 TNO conceptual framework for "E&P Unce

  18. Burns Fact Sheet

    Science.gov (United States)

    ... and Answers page . Share Print E-mail House Image Highlight Header Learn More Highlight Body Other NIGMS Fact Sheets Related Links Up to top This page last reviewed on April 06, 2016 Social Media Links Bookmark & Share Free Subscriptions Twitter Facebook YouTube ...

  19. Ethanol Basics (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2015-01-01

    Ethanol is a widely-used, domestically-produced renewable fuel made from corn and other plant materials. More than 96% of gasoline sold in the United States contains ethanol. Learn more about this alternative fuel in the Ethanol Basics Fact Sheet, produced by the U.S. Department of Energy's Clean Cities program.

  20. SILICON CARBIDE DATA SHEETS

    Science.gov (United States)

    These data sheets present a compilation of a wide range of electrical, optical and energy values for alpha and beta- silicon carbide in bulk and film...spectrum. Energy data include energy bands, energy gap and energy levels for variously-doped silicon carbide , as well as effective mass tables, work

  1. Pseudomonas - Fact Sheet

    OpenAIRE

    Public Health Agency

    2012-01-01

    Fact sheet on Pseudomonas, including:What is Pseudomonas?What infections does it cause?Who is susceptible to pseudomonas infection?How will I know if I have pseudomonas infection?How can Pseudomonas be prevented from spreading?How can I protect myself from Pseudomonas?How is Pseudomonas infection treated?

  2. Fast Light-Sheet Scanner

    Science.gov (United States)

    Hunter, William W., Jr.; Humphreys, William M., Jr.; Bartram, Scott M.

    1995-01-01

    Optomechanical apparatus maintains sheet of pulsed laser light perpendicular to reference axis while causing sheet of light to translate in oscillatory fashion along reference axis. Produces illumination for laser velocimeter in which submicrometer particles entrained in flow illuminated and imaged in parallel planes displaced from each other in rapid succession. Selected frequency of oscillation range upward from tens of hertz. Rotating window continuously shifts sheet of light laterally while maintaining sheet parallel to same plane.

  3. Equivalence Between Squirrel Cage and Sheet Rotor Induction Motor

    Science.gov (United States)

    Dwivedi, Ankita; Singh, S. K.; Srivastava, R. K.

    2016-06-01

    Due to topological changes in dual stator induction motor and high cost of its fabrication, it is convenient to replace the squirrel cage rotor with a composite sheet rotor. For an experimental machine, the inner and outer stator stampings are normally available whereas the procurement of rotor stampings is quite cumbersome and is not always cost effective. In this paper, the equivalence between sheet/solid rotor induction motor and squirrel cage induction motor has been investigated using layer theory of electrical machines, so as to enable one to utilize sheet/solid rotor in dual port experimental machines.

  4. Low Back Pain Fact Sheet

    Science.gov (United States)

    ... Low Back Pain Fact Sheet You are here Home » Disorders » Patient & Caregiver Education » Fact Sheets Low Back Pain Fact Sheet What ... reduction among workers using lumbar support belts, many companies that have ... training and ergonomic awareness programs. The reported injury reduction ...

  5. The Physics of Ice Sheets

    Science.gov (United States)

    Bassis, J. N.

    2008-01-01

    The great ice sheets in Antarctica and Greenland are vast deposits of frozen freshwater that contain enough to raise sea level by approximately 70 m if they were to completely melt. Because of the potentially catastrophic impact that ice sheets can have, it is important that we understand how ice sheets have responded to past climate changes and…

  6. Composites

    Science.gov (United States)

    Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-Nędza, A.; Mackiewicz, S.; Dutkiewicz, J.

    2014-11-01

    It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

  7. Reducing slide sheet injury.

    Science.gov (United States)

    Varcin-Coad, Lynn

    2008-12-01

    Slide sheets are often stated to be the cause of hand and forearm injuries. While there are many other possible reasons injuries to nursing staff, carer and client occur, the most important linking factors relating to musculoskeletal disorders and manual handling of people is the ongoing inappropriateness or lack of suitably designed and equipped work areas. As physiotherapist Lynn Varcin-Coad writes, staff are bearing the brunt of inefficiencies of design and lack of high order risk control.

  8. New directions in the science and technology of advanced sheet explosive formulations and the key energetic materials used in the processing of sheet explosives: Emerging trends.

    Science.gov (United States)

    Talawar, M B; Jangid, S K; Nath, T; Sinha, R K; Asthana, S N

    2015-12-30

    This review presents the work carried out by the international community in the area of sheet explosive formulations and its applications in various systems. The sheet explosive is also named as PBXs and is a composite material in which solid explosive particles like RDX, HMX or PETN are dispersed in a polymeric matrix, forms a flexible material that can be rolled/cut into sheet form which can be applied to any complex contour. The designed sheet explosive must possess characteristic properties such as flexible, cuttable, water proof, easily initiable, and safe handling. The sheet explosives are being used for protecting tanks (ERA), light combat vehicle and futuristic infantry carrier vehicle from different attacking war heads etc. Besides, sheet explosives find wide applications in demolition of bridges, ships, cutting and metal cladding. This review also covers the aspects such as risks and hazard analysis during the processing of sheet explosive formulations, effect of ageing on sheet explosives, detection and analysis of sheet explosive ingredients and the R&D efforts of Indian researchers in the development of sheet explosive formulations. To the best of our knowledge, there has been no review article published in the literature in the area of sheet explosives.

  9. 铝板与复合材料板碾铆连接质量的影响因素%Influencing Factors of Joining Aluminium and Composite Sheets with Rolling Riveting

    Institute of Scientific and Technical Information of China (English)

    黄志超; 张永超; 彭熙琳; 管昌海; 赖家美; 周泽杰; 张玉英

    2015-01-01

    Through rolling riveting and tensile tests of aluminum and composite sheets,this paper analyzed the influences of gasket,different reserved heights of rivets and apertures on connection qual-ity.The results show that the most affects on tensile properties are gaskets,and the bearing capacity of test piece with gasket may be updated by around 50%.Reserved heights have a certain affect on connection performance.Tensile properties declines with increase of rivet height.Bearing capacities are almost the same when the height is as 1.0 mm or 2.0 mm.Aperture has little effect on connection quality.The test results of 6.0mm apertures are better than these of 5.9mm and 6.1 mm apertures. Mechanism of connection performance promotion was explained in aspect of microstructure through metallographic test for specimen with steel rivets.The same tests were conducted by using copper and aluminum rivets,and the results are similar.Corrosion tests of different times show that the corrosion of sulfuric acid solution has little effect on tensile properties in a short period of time.%通过铝板与复合板料碾铆连接与拉伸试验,分析了有无垫圈、不同预留高度及孔径对铝板与复合板料碾铆连接件连接质量的影响。试验结果表明:垫圈对抗拉伸性能影响最大,加垫圈试件比不加垫圈试件承载能力可提升50%左右;预留高度对连接性能有一定影响,随着预留高度增大,试件抗拉伸性能下降,预留高度为1 mm 和2 mm 时承载能力相差不大;孔径对连接强度影响较小,综合对比孔径分别为5.9、6.0、6.1 mm 试件可知,当孔径取6.0 mm 时试验结果较优。对钢铆钉进行了金相试验,从微观组织方面阐述了试件连接性能提升的机理。选取铜、铝铆钉进行碾铆及拉伸试验,所得结论相似。不同时间长度的腐蚀试验则表明较短时间内的硫酸溶液腐蚀对铆接件的拉伸性能影响较小。

  10. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    The Antarctic ice sheet is a major player in the Earth’s climate system and is by far the largest depository of fresh water on the planet. Ice stored in the Antarctic ice sheet (AIS) contains enough water to raise sea level by about 58 m, and ice loss from Antarctica contributed significantly...... Science) Antarctic Ice Sheet (DAIS) model (Shaffer 2014) is forced by reconstructed time series of Antarctic temperature, global sea level and ocean subsurface temperature over the last two glacial cycles. In this talk a modelling work of the Antarctic ice sheet over most of the Cenozoic era using...

  11. An amino acid code for β-sheet packing structure.

    Science.gov (United States)

    Joo, Hyun; Tsai, Jerry

    2014-09-01

    To understand the relationship between protein sequence and structure, this work extends the knob-socket model in an investigation of β-sheet packing. Over a comprehensive set of β-sheet folds, the contacts between residues were used to identify packing cliques: sets of residues that all contact each other. These packing cliques were then classified based on size and contact order. From this analysis, the two types of four-residue packing cliques necessary to describe β-sheet packing were characterized. Both occur between two adjacent hydrogen bonded β-strands. First, defining the secondary structure packing within β-sheets, the combined socket or XY:HG pocket consists of four residues i, i+2 on one strand and j, j+2 on the other. Second, characterizing the tertiary packing between β-sheets, the knob-socket XY:H+B consists of a three-residue XY:H socket (i, i+2 on one strand and j on the other) packed against a knob B residue (residue k distant in sequence). Depending on the packing depth of the knob B residue, two types of knob-sockets are found: side-chain and main-chain sockets. The amino acid composition of the pockets and knob-sockets reveal the sequence specificity of β-sheet packing. For β-sheet formation, the XY:HG pocket clearly shows sequence specificity of amino acids. For tertiary packing, the XY:H+B side-chain and main-chain sockets exhibit distinct amino acid preferences at each position. These relationships define an amino acid code for β-sheet structure and provide an intuitive topological mapping of β-sheet packing.

  12. Functionalized graphene sheet-Poly(vinylidene fluoride) conductive nanocomposites

    KAUST Repository

    Ansari, Seema

    2009-05-01

    PVDF nanocomposites based on functionalized graphene sheets, FGS prepared from graphite oxide, and exfoliated graphite, EG, were prepared by solution processing and compression molding. FGS remains well dispersed in the PVDF composites as evidenced by the lack of the characteristic graphite reflection in the composites. Although the α-phase of PVDF is seen in the EG-based composites, a mixture of α- and β-phases is present in the FGS analogs. SEM and TEM imaging show smooth fractured surfaces with oriented platelets of graphite stacks and obvious debonding from the matrix in the EG-PVDF composites. In contrast, the FGS-PVDF composites show a wrinkled topography of relatively thin graphene sheets bonded well to the matrix. Storage modulus of the composites was increased with FGS and EG concentration. A lower percolation threshold (2 wt %) was obtained for FGSPVDF composites compared to EG-PVDF composites (above 5 wt %). Lastly, the FGS-PVDF composites show an unusual resistance/temperature behavior. The resistance decreases with temperature, indicating an NTC behavior, whereas EG-PVDF composites show a PTC behavior (e.g., the resistance increases with temperature). We attribute the NTC behavior of the FGS based composites to the higher aspect ratio of FGS which leads to contact resistance predominating over tunneling resistance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 888-897, 2009.

  13. Mechanics in Composite Materials and Process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dae Gil

    1993-03-15

    This book includes introduction of composite materials, stress, in-plane stiffness of laminates strain rate, ply stress, failure criterion and bending, composite materials micromechanics, composite plates and micromechanics of composite materials. It also deals with process of composite materials such as autoclave vacuum bag degassing process, connection of composite materials, filament winding process, resin transfer molding, sheet molding compound and compression molding.

  14. Antarctic ice volume for the last 740 ka calculated with a simple ice sheet model

    NARCIS (Netherlands)

    Oerlemans, J.

    2005-01-01

    Fluctuations in the volume of the Antarctic ice sheet for the last 740 ka are calculated by forcing a simple ice sheet model with a sea-level history (from a composite deep sea δ18O record) and a temperature history (from the Dome C deuterium record). Antarctic ice volume reaches maximum values of a

  15. Texture and grain structure of Al-Li-Mg-Zr-Sc alloy sheets

    Energy Technology Data Exchange (ETDEWEB)

    Fridlyander, J.N.; Kolobnev, N.I.; Khokhlatova, L.B. [All-Russian Inst. of Aviation Mater., Moscow (Russian Federation); Berezina, A.L.; Katko, A.V.; Haszler, A.; Keidel, C.

    2000-07-01

    Change of a grain structure nature, of crystallographic texture and of a phase composition in dependence of thermal-mechanical parameters of sheets manufacture was shown with X-ray and electron-microscopic investigations of Al-Li-Mg-Zr-Sc sheets. (orig.)

  16. Photovoltaics Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-02-01

    This fact sheet is an overview of the Photovoltaics (PV) subprogram at the U.S. Department of Energy SunShot Initiative. The U.S. Department of Energy (DOE)’s Solar Energy Technologies Office works with industry, academia, national laboratories, and other government agencies to advance solar PV, which is the direct conversion of sunlight into electricity by a semiconductor, in support of the goals of the SunShot Initiative. SunShot supports research and development to aggressively advance PV technology by improving efficiency and reliability and lowering manufacturing costs. SunShot’s PV portfolio spans work from early-stage solar cell research through technology commercialization, including work on materials, processes, and device structure and characterization techniques.

  17. Soft Costs Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-05-01

    This fact sheet is an overview of the systems integration subprogram at the U.S. Department of Energy SunShot Initiative. Soft costs can vary significantly as a result of a fragmented energy marketplace. In the U.S., there are 18,000 jurisdictions and 3,000 utilities with different rules and regulations for how to go solar. The same solar equipment may vary widely in its final installation price due to process and market variations across jurisdictions, creating barriers to rapid industry growth. SunShot supports the development of innovative solutions that enable communities to build their local economies and establish clean energy initiatives that meet their needs, while at the same time creating sustainable solar market conditions.

  18. Systems Integration Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-06-01

    This fact sheet is an overview of the Systems Integration subprogram at the U.S. Department of Energy SunShot Initiative. The Systems Integration subprogram enables the widespread deployment of safe, reliable, and cost-effective solar energy technologies by addressing the associated technical and non-technical challenges. These include timely and cost-effective interconnection procedures, optimal system planning, accurate prediction of solar resources, monitoring and control of solar power, maintaining grid reliability and stability, and many more. To address the challenges associated with interconnecting and integrating hundreds of gigawatts of solar power onto the electricity grid, the Systems Integration program funds research, development, and demonstration projects in four broad, interrelated focus areas: grid performance and reliability, dispatchability, power electronics, and communications.

  19. Material Safety Data Sheets (MSDS)

    CERN Document Server

    Lalley, J

    About 250.000 Material Safety Data sheets from the U.S. Government Department of Defense MSDS database, a mirror of data from siri.uvm.edu, MSDS sheets maintained by Cornell University Environmental Health and Safety and other Cornell departments.

  20. Skill Sheets for Agricultural Machinery.

    Science.gov (United States)

    Iowa State Univ. of Science and Technology, Ames. Dept. of Agricultural Education.

    This set of 21 skill sheets for agricultural machinery was developed for use in high school and vocational school agricultural mechanics programs. Each sheet covers a single operational procedure for a piece of agricultural machinery, and includes: (1) a diagram, (2) a step-by-step operational procedure, (3) abilities or understandings taught, (4)…

  1. Analytical ice-sheet models

    NARCIS (Netherlands)

    Oerlemans, J.

    2005-01-01

    To model present-day or palaeo-ice sheets in a realistic way requires numerical methods with high spatial resolution and a comprehensive description of the relevant physical processes. Nevertheless, some basic elements of the interaction between ice sheets and climate can be investigated by simple m

  2. 内氧化法制备Cu-Al2O3薄板复合材料及其重熔后的组织性能%Cu-Al2O3 composite sheets prepared by internal oxidation and its microstructure and properties after re-melting

    Institute of Scientific and Technical Information of China (English)

    李新; 田保红; 任凤章; 熊毅; 魏世忠; 马景灵

    2016-01-01

    Cu-Al2O3 composite sheets were prepared by internal oxidation used Cu-Al alloy sheets with different Al content (0.2%,0.35% and 0.5%,mass) as raw materials.Microstructure and properties of the Cu-Al2O3 composite sheets under the same oxidation temperature and time were studied.Meanwhile,the Cu-Al2O3 bulk composites were tried to prepare by re-melting method used the Cu-Al2O3 composites sheets with dispersive distribution of Al2O3 particles.The results show that the external grains in the internal oxidation layer of the Cu-Al2O3 composite sheets are smaller than that of internal grains.With the increasing Al content,under the same oxidation time,the internal oxidation layer depth becomes smaller and the internal grains become coarser.A large amount of the γ-Al2O3 phase is distributed in the Cu matrix of the composites prepared by internal oxidation.The size of the γ-Al2O3 particles is 10-30 nm and the particle spacing is 20-70 nm.The γ-Al2O3 phase strengthens the Cu matrix,so the hardness of the composites surface is significantly increased compared with the alloy,and the hardness gradually decreases from the surface to the inside.Al2O3 particles in the Cu-Al2O3 sheets aggregate and grow after re-melting.Thus,re-melting of composite sheets to prepare the Cu-Al2O3 bulk composites is unfeasible.%采用不同Al含量(0.20%、0.35%和0.50%,质量分数)的Cu-Al合金薄板内氧化法制备Cu-Al2O3薄板复合材料.对比分析了相同内氧化温度和时间下,不同Al含量的Cu-Al合金薄板内氧化制备出的Cu-Al2O3薄板复合材料的组织性能.并尝试采用Cu-Al2O3薄板复合材料重熔法制备Al2O3颗粒弥散分布的Cu-Al2O3块体复合材料.结果表明,Cu-Al2O3薄板复合材料内氧化层外部晶粒比内部晶粒细小;随着Al质量分数的增加,在相同的内氧化时间下,内氧化层的深度逐渐减小,内氧化层的内部晶粒逐渐粗化;内氧化后所得复合材料的Cu基体中弥散分布着大量的γ-Al2

  3. Supraglacial bacterial community structures vary across the Greenland ice sheet

    DEFF Research Database (Denmark)

    Cameron, Karen A.; Stibal, Marek; Zarsky, Jakub D.;

    2016-01-01

    The composition and spatial variability of microbial communities that reside within the extensive (>200 000 km(2)) biologically active area encompassing the Greenland ice sheet (GrIS) is hypothesized to be variable. We examined bacterial communities from cryoconite debris and surface ice across...

  4. 压型钢板-陶粒混凝土组合楼板火灾响应及火灾后受力性能试验研究%Experimental study of fire response and post-fire mechanical performance of profiled sheet-ceramsite concrete composite floor

    Institute of Scientific and Technical Information of China (English)

    王新堂; 周明; 王万祯

    2012-01-01

    In order to investigate the fire behavior of profiled sheet-ceramsite concrete composite floors ( abbreviated as PCCF) ,the fire response and structural response of two simply supported PCCF under static load were first obtained through fire experiment. Then experimental study of the post-fire mechanical performance of two composite floors after exposure to fire were carried out, and the static test of the profiled sheet-ceramsite concrete composite floor which had the same construction and dimension as the floor subjected to fire load presented here was conducted. The experimental results show that the fire-resistant ability and the post-fire bearing capacity of the composite floor can be weakened by the welding studs set in the floor. Compared with the composite floor with the same construction and dimension as the floor subjected to fire load, the failure pattern of the profiled sheet-ceramsite concrete composite floor after exposure to fire has great variation, but still has higher post-fire bearing capacity and better mechanical behavior. It is shown that the composite floor after exposure to fire exhibits the failure pattern of bending failure and the composite floor which is not subjected to fire load exhibits the failure pattern of shearing failure.%为了分析压型钢板-陶粒混凝土组合楼板的火灾响应,首先对受荷条件下的2块简支陶粒混凝土组合楼板进行了火灾行为试验,得到了其火灾温度响应及位移响应。在此基础上,进一步对2块受火后的压型钢板-陶粒混凝土组合楼板进行了火灾后受力性能试验研究,并对1块具有相同参数的组合楼板开展了常温下静载试验。结果表明:在楼板内部设置焊接栓钉将减弱组合楼板的抗火性能、降低组合楼板火灾后的承载力;与未受火作用的同样规格的组合楼板相比,火灾后压型钢板一陶粒混凝土组合楼板的破坏形式发生较大变化,但仍具有较高的承

  5. Number & operations task & drill sheets

    CERN Document Server

    Reed, Nat

    2011-01-01

    For grades 6-8, our State Standards-based combined resource meets the number & operations concepts addressed by the NCTM standards and encourages the students to review the concepts in unique ways. The task sheets introduce the mathematical concepts to the students around a central problem taken from real-life experiences, while the drill sheets provide warm-up and timed practice questions for the students to strengthen their procedural proficiency skills. Included are problems involving place value, fractions, addition, subtraction and using money. The combined task & drill sheets offer spac

  6. Seeing graphene-based sheets

    Directory of Open Access Journals (Sweden)

    Jaemyung Kim

    2010-03-01

    Full Text Available Graphene-based sheets such as graphene, graphene oxide and reduced graphene oxide have stimulated great interest due to their promising electronic, mechanical and thermal properties. Microscopy imaging is indispensable for characterizing these single atomic layers, and oftentimes is the first measure of sample quality. This review provides an overview of current imaging techniques for graphene-based sheets and highlights a recently developed fluorescence quenching microscopy technique that allows high-throughput, high-contrast imaging of graphene-based sheets on arbitrary substrate and even in solution.

  7. APPLICATION OF ARCH STEEL SHEET CONCRETE COMPOSITE SHEAR WALL CONSTRUCTION TECHNIQUE IN BEIJING OLYMPIC PARK TOWER PROJECT%圆弧钢板混凝土组合剪力墙施工技术在北京奥林匹克公园瞭望塔工程中的应用

    Institute of Scientific and Technical Information of China (English)

    杨秉钧; 焦勇; 徐德林; 付雅娣

    2013-01-01

    The Watch Tower Project in Beijing Olympic Park is a high-rise steel structure with a huge volume. After careful calculation, it is determined to use steel sheet composite shear wall structure, which could not only bear the load of upper part, but also integrate with the tower base to stabilize the tower body. Under precondition of ensuring structure safety, building functions are successfully realized and ideal application effects are obtained through adoption of a series construction techniques, including steel column installation, steel sheet wall installation, steel bar binding, formwork installation, concrete pouring, formwork dismantlement and next steel bar binding, as well as successful disposal of difficulties in connection between steel bar and steel sheet.%北京奥林匹克公园瞭望塔工程为高耸钢结构,塔体总量很大,经过详细计算,决定采用钢板组合剪力墙结构,既能承受上部荷载,还能与塔座组成整体形成对塔身的嵌固.通过采取钢柱安装、钢板墙安装、钢筋绑扎、模板安装、混凝土浇筑、模板拆除、下一步钢筋绑扎等一系列施工技术,以及对钢筋与钢板之间的连接这一难点问题进行处理,在保证结构安全性的前提下,很好地实现了建筑功能,取得了理想的应用效果.

  8. Ruthenium-containing P450 inhibitors for dual enzyme inhibition and DNA damage.

    Science.gov (United States)

    Zamora, Ana; Denning, Catherine A; Heidary, David K; Wachter, Erin; Nease, Leona A; Ruiz, José; Glazer, Edith C

    2017-02-14

    Cytochrome P450s are key players in drug metabolism, and overexpression in tumors is associated with significant resistance to many medicinal agents. Consequently, inhibition of P450s could serve as a strategy to restore drug efficacy. However, the widespread expression of P450s throughout the human body and the critical roles they play in various biosynthetic pathways motivates the development of P450 inhibitors capable of controlled local administration. Ruthenium complexes containing P450 inhibitors as ligands were synthesized in order to develop pro-drugs that can be triggered to release the inhibitors in a spatially and temporally controlled fashion. Upon light activation the compounds release ligands that directly bind and inhibit P450 enzymes, while the ruthenium center is able to directly damage DNA.

  9. Perforation of metal sheets

    DEFF Research Database (Denmark)

    Steenstrup, Jens Erik

    The main purposes of this project are:1. Development of a dynamic model for the piercing and performation process2. Analyses of the main parameters3. Establishing demands for process improvements4. Expansion of the existing parameter limitsThe literature survey describes the process influence of ...... and a tool designed for punches with minimum length. Further, a systematic problem solving procedure is established. This procedure includes simulation as an integrated part, necessary for problem detection and to predict a favourable solution....... simulation is focused on the sheet deformation. However, the effect on the tool and press is included. The process model is based on the upper bound analysis in order to predict the force progress and hole characteristics etc. Parameter analyses are divided into two groups, simulation and experimental tests....... The tests complement each other in order to reveal the dominant parameters, which are decisive for the final product. Crucial demands are established to enable the desired improvements, focused on expanding the existing parameter limits. The demands include a justified need regarding a high-speed press...

  10. Protein unfolding versus β-sheet separation in spider silk nanocrystals

    Science.gov (United States)

    Alam, Parvez

    2014-03-01

    In this communication a mechanism for spider silk strain hardening is proposed. Shear failure of β-sheet nanocrystals is the first failure mode that gives rise to the creation of smaller nanocrystals, which are of higher strength and stiffness. β-sheet unfolding requires more energy than nanocrystal separation in a shear mode of failure. As a result, unfolding occurs after the nanocrystals separate in shear. β-sheet unfolding yields a secondary strain hardening effect once the β-sheet conformation is geometrically stable and acts like a unidirectional fibre in a fibre reinforced composite. The mechanism suggested herein is based on molecular dynamics calculations of residual inter-β-sheet separation strengths against residual intra-β-sheet unfolding strengths.

  11. Biological studies and electrical conductivity of paper sheet based on PANI/PS/Ag-NPs nanocomposite.

    Science.gov (United States)

    Youssef, A M; Mohamed, S A; Abdel-Aziz, M S; Abdel-Aziz, M E; Turky, G; Kamel, S

    2016-08-20

    Polyaniline (PANI) with/without polystyrene (PS), was successfully manufactured in the occurrence of dispersed pulp fibers via the oxidative polymerization reaction of aniline monomer to produce conductive paper sheets containing PANI, PANI/PS composites. Additionally, sliver nitrate (Ag-NO3) was added by varied loadings to the oxidative polymerization of aniline monomer to provide sliver nanoparticles (Ag-NPs) emptied into the prepared paper sheets. The prepared paper sheets were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy (IR), the mechanical properties of the prepared paper sheets were evaluated. Moreover, the electrical conductivity and biological studies such as cellulases assay, Microorganism & culture condition and detection of the released of Ag-NPs were evaluated. Furthermore, the prepared paper sheets were displayed good antibacterial properties contrary to gram positive and gram negative bacteria. Consequently, the prepared paper sheet may be used as novel materials for packaging applications.

  12. Analytical Evaluation of Fibre-Reinforced Plastic Corrugated Sheet

    Directory of Open Access Journals (Sweden)

    C. K. Gautam

    1998-01-01

    Full Text Available Fibre-reinforced' composites playa lead role as advanced materials in modem day structures.This paper reports fabrication and testing offibre-reinforced corrugated sheet employing 4-point bend loading. An in-depth analysis has been carried out using ANSYS, a finite element method package.The theoretical results obtained are compared with the experimental values. The values ofboth inputsshowed similar results. conforming at a particular boundary condition. However, more similarexperiments "on such fibre-reinforced plastic corrugated sheets have been suggested for -better comparison.

  13. The Brittleness Of Zn-Cu-Ti Sheet Alloys

    Directory of Open Access Journals (Sweden)

    Boczkal G.

    2015-09-01

    Full Text Available At temperatures below 5°C, the ductility of ZnCuTi alloy sheets is observed to suffer a drastic drop in direction transverse to the rolling direction. Studies have shown that the critical temperature at which this phenomenon occurs is strongly dependent on the alloy structure and parameters of the sheet metal production process. Quite important is also the role of micro-inhomogeneity arising in the chemical composition of the alloy matrix, directly related with the structure of intermetallic precipitates containing Cu and Ti.

  14. Mechanical recycling of continuous fiber-reinforced thermoplastic sheets

    Science.gov (United States)

    Moritzer, Elmar; Heiderich, Gilmar

    2016-03-01

    This contribution examines possible material recycling of offcuts generated during the production of continuous-fiber-reinforced composite sheets. These sheets consist of a polyamide 6 matrix and glass fiber fabric. In the initial step, the offcut is shredded to obtain particles; following that, the particles are processed in a twin-screw process to produce fiber-reinforced plastic pellets with varying fiber contents. These pellets are intended for use in injection molding processes as a substitution for new raw materials. This investigation centers on the mechanical properties which can be achieved with the recycled material after both the twin-screw process and injection molding.

  15. State Fact Sheets on COPD

    Science.gov (United States)

    ... Submit Search The CDC Chronic Obstructive Pulmonary Disease (COPD) Note: Javascript is disabled or is not supported ... message, please visit this page: About CDC.gov . COPD Homepage Data and Statistics Fact Sheets Publications Publications ...

  16. Palaeoclimate science: Pulsating ice sheet

    Science.gov (United States)

    Vieli, Andreas

    2017-02-01

    During the last ice age, huge numbers of icebergs were episodically discharged from an ice sheet that covered North America. Numerical modelling suggests that these events resulted from a conceptually simple feedback cycle. See Letter p.332

  17. Crescent Lake Wilderness Reference Sheet

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Reference sheet includes information about Crescent Lake National Wildlife Refuge, and results of the public hearing for Crescent Lake Wilderness Proposal.

  18. Industrial Stormwater Fact Sheet Series

    Science.gov (United States)

    Fact sheets for the industrial sectors regulated by the MSGP. Each describes the types of facilities included in the sector, typical pollutants associated with the sector, and types of stormwater control measures used to minimize pollutant discharge.

  19. 2008 Swimming Season Fact Sheets

    Science.gov (United States)

    To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

  20. 2007 Swimming Season Fact Sheets

    Science.gov (United States)

    To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

  1. 2006 Swimming Season Fact Sheets

    Science.gov (United States)

    To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

  2. 2009 Swimming Season Fact Sheets

    Science.gov (United States)

    To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

  3. 2010 Swimming Season Fact Sheets

    Science.gov (United States)

    To help beachgoers make informed decisions about swimming at U.S. beaches, EPA annually publishes state-by-state data about beach closings and advisories for the previous year's swimming season. These fact sheets summarize that information by state.

  4. Energy information sheets, July 1998

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-07-01

    The National Energy Information Center (NEIC), as part of its mission, provides energy information and referral assistance to Federal, State, and local governments, the academic community, business and industrial organizations, and the public. The Energy Information Sheets was developed to provide general information on various aspects of fuel production, prices, consumption, and capability. Additional information on related subject matter can be found in other Energy Information Administration (EIA) publications as referenced at the end of each sheet.

  5. Energy information sheets, September 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    The National Energy Information Center (NEIC), as part of its mission, provides energy information and referral assistance to Federal, State, and local governments, the academic community, business and industrial organizations, and the public. The Energy Information Sheets was developed to provide general information on various aspects of fuel production, prices, consumption, and capability. Additional information on related subject matter can be found in other Energy Information Administration (EIA) publications as referenced at the end of each sheet.

  6. The 2013 social balance sheet

    OpenAIRE

    Pierrette Heuse

    2014-01-01

    The transposition into national law of Directive 2013/34/EU on the annual financial statements of companies, expected by no later than July 2015, could alter the statistical obligations on small firms in connection with the filing of their annual accounts. In any case, the social balance sheet can no longer form an integral part of their accounts. Nevertheless, it contains original information whose usefulness is highlighted, on the basis of the social balance sheets for 2012, by examining th...

  7. Younger Dryas interval and outflow from the Laurentide ice sheet

    Science.gov (United States)

    Moore, T.C.; Walker, J.C.G.; Rea, David K.; Lewis, C.F.M.; Shane, L.C.K.; Smith, A.J.

    2000-01-01

    A boxmodel of the Great Lakes is used to estimate meltwater flow into the North Atlantic between 8000 and 14,000 calendar years B.P. Controls on the model include the oxygen isotopic composition of meltwaters and lake waters as measured in the shells of ostracodes. Outflow rates are highest when oxygen isotopic values of the lake waters are most negative, denoting a maximum glacial meltwater component. Flow rates reach maximum values before the onset of the Younger Dryas and after it ends. These maxima appear to be correlative with the major meltwater pulses MWP 1A and 1B. Although the resumption of North Atlantic Deep Water formation may be tied to the reduction in ice sheet melting, neither the onset nor the end of the Younger Dryas, as recorded in the Greenland Ice Sheet Project (GISP2) records, appear tied to maxima in meltwater outflow from the Laurentide ice sheet. Copyright 2000 by the American Geophysical Union.

  8. Cyclic modular beta-sheets.

    Science.gov (United States)

    Woods, R Jeremy; Brower, Justin O; Castellanos, Elena; Hashemzadeh, Mehrnoosh; Khakshoor, Omid; Russu, Wade A; Nowick, James S

    2007-03-07

    The development of peptide beta-hairpins is problematic, because folding depends on the amino acid sequence and changes to the sequence can significantly decrease folding. Robust beta-hairpins that can tolerate such changes are attractive tools for studying interactions involving protein beta-sheets and developing inhibitors of these interactions. This paper introduces a new class of peptide models of protein beta-sheets that addresses the problem of separating folding from the sequence. These model beta-sheets are macrocyclic peptides that fold in water to present a pentapeptide beta-strand along one edge; the other edge contains the tripeptide beta-strand mimic Hao [JACS 2000, 122, 7654] and two additional amino acids. The pentapeptide and Hao-containing peptide strands are connected by two delta-linked ornithine (deltaOrn) turns [JACS 2003, 125, 876]. Each deltaOrn turn contains a free alpha-amino group that permits the linking of individual modules to form divalent beta-sheets. These "cyclic modular beta-sheets" are synthesized by standard solid-phase peptide synthesis of a linear precursor followed by solution-phase cyclization. Eight cyclic modular beta-sheets 1a-1h containing sequences based on beta-amyloid and macrophage inflammatory protein 2 were synthesized and characterized by 1H NMR. Linked cyclic modular beta-sheet 2, which contains two modules of 1b, was also synthesized and characterized. 1H NMR studies show downfield alpha-proton chemical shifts, deltaOrn delta-proton magnetic anisotropy, and NOE cross-peaks that establish all compounds but 1c and 1g to be moderately or well folded into a conformation that resembles a beta-sheet. Pulsed-field gradient NMR diffusion experiments show little or no self-association at low (

  9. Horizontal electromagnetic casting of thin metal sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Lari, Robert J. (Aurora, IL); Praeg, Walter F. (Palos Park, IL); Turner, Larry R. (Naperville, IL)

    1988-01-01

    Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

  10. Horizontal electromagnetic casting of thin metal sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Lari, Robert J. (Aurora, IL); Praeg, Walter F. (Palos Park, IL); Turner, Larry R. (Naperville, IL)

    1987-01-01

    Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

  11. Automobile sheet metal part production with incremental sheet forming

    Directory of Open Access Journals (Sweden)

    İsmail DURGUN

    2016-02-01

    Full Text Available Nowadays, effect of global warming is increasing drastically so it leads to increased interest on energy efficiency and sustainable production methods. As a result of adverse conditions, national and international project platforms, OEMs (Original Equipment Manufacturers, SMEs (Small and Mid-size Manufacturers perform many studies or improve existing methodologies in scope of advanced manufacturing techniques. In this study, advanced manufacturing and sustainable production method "Incremental Sheet Metal Forming (ISF" was used for sheet metal forming process. A vehicle fender was manufactured with or without die by using different toolpath strategies and die sets. At the end of the study, Results have been investigated under the influence of method and parameters used.Keywords: Template incremental sheet metal, Metal forming

  12. Fabrication and microwave shielding properties of free standing polyaniline-carbon fiber thin sheets

    Energy Technology Data Exchange (ETDEWEB)

    Joon, Seema [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Department of Physics, DCRUST Murthal, Sonepat, Haryana 130001 (India); PDM College of Engineering, Bahadurgarh, Haryana 124507 (India); Kumar, Rakesh [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); PDM College of Engineering, Bahadurgarh, Haryana 124507 (India); Singh, Avanish Pratap [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Shukla, Rajni [Department of Physics, DCRUST Murthal, Sonepat, Haryana 130001 (India); Dhawan, S.K., E-mail: skdhawan@mail.nplindia.ernet.in [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2015-06-15

    Attempt has been made to synthesize polyaniline-carbon fiber (PANI-CF) composite via in-situ emulsion polymerization using β-naphthalene sulphonic acid (NSA) which acts as both surfactant as well as dopant. Free standing PANI-CF thin sheets are prepared which have electrical conductivity ∼1.02 S/cm with improved mechanical strength and thermal stability. The scanning electron microscopy is used to study the surface morphology of the composites. Structural characterization is done by using XRD. The dielectric attributes (ε* = ε′ − iε″) of PANI-CF sheets are calculated using experimental S parameters (S{sub 11}, S{sub 12}) by Nicolson Ross Wier equations. It has been demonstrated that these sheets show maximum shielding effectiveness (SE) of 31.9 dB at 12.4 GHz frequency at a thickness of 1.5 mm. Free standing PANI-CF sheets so prepared have a potential for X-band microwave absorber application. - Highlights: • Free standing polyaniline-carbon fiber thin sheets fabricated for EMI shielding. • The mechanical strength of sheets improves with phenolic resin loading. • The dielectric parameters were calculated by Nicholson Ross Wier equations. • Sheets (1.5 mm thickness) demonstrate SE of 31.9 dB at 12.4 GHz frequency. • Sheets find potential application for X-band microwave absorption.

  13. Capillary wrinkling of thin bilayer polymeric sheets

    Science.gov (United States)

    Chang, Jooyoung; Menon, Narayanan; Russell, Thomas

    We have investigated capillary force induced wrinkling on a floated polymeric bilayer thin sheet. The origin of the wrinkle pattern is compressional hoop stress caused by the capillary force of a water droplet placed on the floated polymeric thin sheet afore investigated. Herein, we study the effect of the differences of surface energy arising from the hydrophobicity of Polystyrene (PS Mw: 97 K, Contact Angle: 88 º) and the hydrophilicity of Poly(methylmethacrylate) (PMMA Mw: 99K, Contact Angle: 68 º) on two sides of a bilayer film. We measure the number and the length of the wrinkles by broadly varying the range of thicknesses of top (9 nm to 550 nm) and bottom layer (25 nm to 330 nm). At the same, there is only a small contrast in mechanical properties of the two layers (PS E = 3.4 GPa, and PMMA E = 3 GPa). The number of the wrinkles is not strongly affected by the composition (PS(Top)/PMMA(Bottom) or PMMA(Top)/PS(Bottom)) and the thickness of each and overall bilayer system. However, the length of the wrinkle is governed by the contact angle of the drop on the top layer of bilayer system. We also compare this to the wrinkle pattern obtained in monolayer systems over a wide range of thickness from PS and PMMA (7 nm to 1 μm). W.M. Keck Foundation.

  14. Hybrid Piezoelectric/Fiber-Optic Sensor Sheets

    Science.gov (United States)

    Lin, Mark; Qing, Xinlin

    2004-01-01

    Hybrid piezoelectric/fiber-optic (HyPFO) sensor sheets are undergoing development. They are intended for use in nondestructive evaluation and long-term monitoring of the integrity of diverse structures, including aerospace, aeronautical, automotive, and large stationary ones. It is anticipated that the further development and subsequent commercialization of the HyPFO sensor systems will lead to economic benefits in the form of increased safety, reduction of life-cycle costs through real-time structural monitoring, increased structural reliability, reduction of maintenance costs, and increased readiness for service. The concept of a HyPFO sensor sheet is a generalization of the concept of a SMART Layer(TradeMark), which is a patented device that comprises a thin dielectric film containing an embedded network of distributed piezoelectric actuator/sensors. Such a device can be mounted on the surface of a metallic structure or embedded inside a composite-material structure during fabrication of the structure. There is has been substantial interest in incorporating sensors other than piezoelectric ones into SMART Layer(TradeMark) networks: in particular, because of the popularity of the use of fiber-optic sensors for monitoring the "health" of structures in recent years, it was decided to incorporate fiber-optic sensors, giving rise to the concept of HyPFO devices.

  15. Optimal swimming of a sheet.

    Science.gov (United States)

    Montenegro-Johnson, Thomas D; Lauga, Eric

    2014-06-01

    Propulsion at microscopic scales is often achieved through propagating traveling waves along hairlike organelles called flagella. Taylor's two-dimensional swimming sheet model is frequently used to provide insight into problems of flagellar propulsion. We derive numerically the large-amplitude wave form of the two-dimensional swimming sheet that yields optimum hydrodynamic efficiency: the ratio of the squared swimming speed to the rate-of-working of the sheet against the fluid. Using the boundary element method, we show that the optimal wave form is a front-back symmetric regularized cusp that is 25% more efficient than the optimal sine wave. This optimal two-dimensional shape is smooth, qualitatively different from the kinked form of Lighthill's optimal three-dimensional flagellum, not predicted by small-amplitude theory, and different from the smooth circular-arc-like shape of active elastic filaments.

  16. Highly sensitive and selective dopamine biosensor based on 3,4,9,10-perylene tetracarboxylic acid functionalized graphene sheets/multi-wall carbon nanotubes/ionic liquid composite film modified electrode.

    Science.gov (United States)

    Niu, Xiuli; Yang, Wu; Guo, Hao; Ren, Jie; Gao, Jinzhang

    2013-03-15

    A sensitive and selective electrochemical sensor for determination of dopamine (DA) was fabricated based on 3,4,9,10-perylene tetracarboxylic acid functionalized graphene sheets, multi-wall carbon nanotubes and ionic liquid modified glass carbon electrode and the properties of modified electrode were characterized by scanning electron microscopy, transmission electron microscope and electrochemical impedance spectroscopy. The modified electrode showed excellent electrocatalytic activity toward the oxidation of DA. Meanwhile, a possible reaction mechanism related to the oxidation of DA was proposed. The differential pulse voltammetry was used for the determination of DA in the presence of 500 μM ascorbic acid and 330 μM uric acid under the optimum conditions and a good linear relationship between peak current and the concentration of DA was obtained in the concentration range from 0.03 μM to 3.82 mM with a detection limit of 1.2×10(-9) M (S/N=3). Moreover, the proposed method was successfully applied to determine DA in real sample and satisfactory results were obtained. The results showed that the modified electrode exhibits an excellent catalytic activity, good sensitivity, reproducibility and long-term stability.

  17. Sheet Bending using Soft Tools

    Science.gov (United States)

    Sinke, J.

    2011-05-01

    Sheet bending is usually performed by air bending and V-die bending processes. Both processes apply rigid tools. These solid tools facilitate the generation of software for the numerical control of those processes. When the lower rigid die is replaced with a soft or rubber tool, the numerical control becomes much more difficult, since the soft tool deforms too. Compared to other bending processes the rubber backed bending process has some distinct advantages, like large radius-to-thickness ratios, applicability to materials with topcoats, well defined radii, and the feasibility of forming details (ridges, beads). These advantages may give the process exclusive benefits over conventional bending processes, not only for industries related to mechanical engineering and sheet metal forming, but also for other disciplines like Architecture and Industrial Design The largest disadvantage is that also the soft (rubber) tool deforms. Although the tool deformation is elastic and recovers after each process cycle, the applied force during bending is related to the deformation of the metal sheet and the deformation of the rubber. The deformation of the rubber interacts with the process but also with sheet parameters. This makes the numerical control of the process much more complicated. This paper presents a model for the bending of sheet materials using a rubber lower die. This model can be implemented in software in order to control the bending process numerically. The model itself is based on numerical and experimental research. In this research a number of variables related to the tooling and the material have been evaluated. The numerical part of the research was used to investigate the influence of the features of the soft lower tool, like the hardness and dimensions, and the influence of the sheet thickness, which also interacts with the soft tool deformation. The experimental research was focused on the relation between the machine control parameters and the most

  18. Ice sheet hydrology - a review

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Peter; Naeslund, Jens-Ove [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden); Rodhe, Lars [Geological Survey of Sweden, Uppsala (Sweden)

    2007-03-15

    This report summarizes the theoretical knowledge on water flow in and beneath glaciers and ice sheets and how these theories are applied in models to simulate the hydrology of ice sheets. The purpose is to present the state of knowledge and, perhaps more importantly, identify the gaps in our understanding of ice sheet hydrology. Many general concepts in hydrology and hydraulics are applicable to water flow in glaciers. However, the unique situation of having the liquid phase flowing in conduits of the solid phase of the same material, water, is not a commonly occurring phenomena. This situation means that the heat exchange between the phases and the resulting phase changes also have to be accounted for in the analysis. The fact that the solidus in the pressure-temperature dependent phase diagram of water has a negative slope provides further complications. Ice can thus melt or freeze from both temperature and pressure variations or variations in both. In order to provide details of the current understanding of water flow in conjunction with deforming ice and to provide understanding for the development of ideas and models, emphasis has been put on the mathematical treatments, which are reproduced in detail. Qualitative results corroborating theory or, perhaps more often, questioning the simplifications made in theory, are also given. The overarching problem with our knowledge of glacier hydrology is the gap between the local theories of processes and the general flow of water in glaciers and ice sheets. Water is often channelized in non-stationary conduits through the ice, features which due to their minute size relative to the size of glaciers and ice sheets are difficult to incorporate in spatially larger models. Since the dynamic response of ice sheets to global warming is becoming a key issue in, e.g. sea-level change studies, the problems of the coupling between the hydrology of an ice sheet and its dynamics is steadily gaining interest. New work is emerging

  19. Graphite/Cyanate Ester Face Sheets for Adaptive Optics

    Science.gov (United States)

    Bennett, Harold; Shaffer, Joseph; Romeo, Robert

    2008-01-01

    It has been proposed that thin face sheets of wide-aperture deformable mirrors in adaptive-optics systems be made from a composite material consisting of cyanate ester filled with graphite. This composite material appears to offer an attractive alternative to low-thermal-expansion glasses that are used in some conventional optics and have been considered for adaptive-optics face sheets. Adaptive-optics face sheets are required to have maximum linear dimensions of the order of meters or even tens of meters for some astronomical applications. If the face sheets were to be made from low-thermal-expansion glasses, then they would also be required to have thicknesses of the order of a millimeter so as to obtain the optimum compromise between the stiffness needed for support and the flexibility needed to enable deformation to controlled shapes by use of actuators. It is difficult to make large glass sheets having thicknesses less than 3 mm, and 3-mm-thick glass sheets are too stiff to be deformable to the shapes typically required for correction of wavefronts of light that has traversed the terrestrial atmosphere. Moreover, the primary commercially produced candidate low-thermal-expansion glass is easily fractured when in the form of thin face sheets. Graphite-filled cyanate ester has relevant properties similar to those of the low-expansion glasses. These properties include a coefficient of thermal expansion (CTE) of the order of a hundredth of the CTEs of other typical mirror materials. The Young s modulus (which quantifies stiffness in tension and compression) of graphite-filled cyanate ester is also similar to the Young's moduli of low-thermal-expansion glasses. However, the fracture toughness of graphite-filled cyanate ester is much greater than that of the primary candidate low-thermal-expansion glass. Therefore, graphite-filled cyanate ester could be made into nearly unbreakable face sheets, having maximum linear dimensions greater than a meter and thicknesses of

  20. Groundwater flow modelling under ice sheet conditions. Scoping calculations

    Energy Technology Data Exchange (ETDEWEB)

    Jaquet, O.; Namar, R. (In2Earth Modelling Ltd (Switzerland)); Jansson, P. (Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden))

    2010-10-15

    The potential impact of long-term climate changes has to be evaluated with respect to repository performance and safety. In particular, glacial periods of advancing and retreating ice sheet and prolonged permafrost conditions are likely to occur over the repository site. The growth and decay of ice sheets and the associated distribution of permafrost will affect the groundwater flow field and its composition. As large changes may take place, the understanding of groundwater flow patterns in connection to glaciations is an important issue for the geological disposal at long term. During a glacial period, the performance of the repository could be weakened by some of the following conditions and associated processes: - Maximum pressure at repository depth (canister failure). - Maximum permafrost depth (canister failure, buffer function). - Concentration of groundwater oxygen (canister corrosion). - Groundwater salinity (buffer stability). - Glacially induced earthquakes (canister failure). Therefore, the GAP project aims at understanding key hydrogeological issues as well as answering specific questions: - Regional groundwater flow system under ice sheet conditions. - Flow and infiltration conditions at the ice sheet bed. - Penetration depth of glacial meltwater into the bedrock. - Water chemical composition at repository depth in presence of glacial effects. - Role of the taliks, located in front of the ice sheet, likely to act as potential discharge zones of deep groundwater flow. - Influence of permafrost distribution on the groundwater flow system in relation to build-up and thawing periods. - Consequences of glacially induced earthquakes on the groundwater flow system. Some answers will be provided by the field data and investigations; the integration of the information and the dynamic characterisation of the key processes will be obtained using numerical modelling. Since most of the data are not yet available, some scoping calculations are performed using the

  1. Engineering tubular bone using mesenchymal stem cell sheets and coral particles

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Wenxin [Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, No.229 North Taibai Road, Xi’an 710069 (China); Ma, Dongyang [Department of Oral and Maxillofacial Surgery, Lanzhou General Hospital, Lanzhou Command of PLA, BinHe 333 South Road, Lanzhou 730052 (China); Yan, Xingrong; Liu, Liangqi; Cui, Jihong; Xie, Xin; Li, Hongmin [Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, No.229 North Taibai Road, Xi’an 710069 (China); Chen, Fulin, E-mail: chenfl@nwu.edu.cn [Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, No.229 North Taibai Road, Xi’an 710069 (China)

    2013-04-19

    Highlights: • We developed a novel engineering strategy to solve the limitations of bone grafts. • We fabricated tubular constructs using cell sheets and coral particles. • The composite constructs showed high radiological density and compressive strength. • These characteristics were similar to those of native bone. -- Abstract: The development of bone tissue engineering has provided new solutions for bone defects. However, the cell-scaffold-based approaches currently in use have several limitations, including low cell seeding rates and poor bone formation capacity. In the present study, we developed a novel strategy to engineer bone grafts using mesenchymal stem cell sheets and coral particles. Rabbit bone marrow mesenchymal stem cells were continuously cultured to form a cell sheet with osteogenic potential and coral particles were integrated into the sheet. The composite sheet was then wrapped around a cylindrical mandrel to fabricate a tubular construct. The resultant tubular construct was cultured in a spinner-flask bioreactor and subsequently implanted into a subcutaneous pocket in a nude mouse for assessment of its histological characteristics, radiological density and mechanical property. A similar construct assembled from a cell sheet alone acted as a control. In vitro observations demonstrated that the composite construct maintained its tubular shape, and exhibited higher radiological density, compressive strength and greater extracellular matrix deposition than did the control construct. In vivo experiments further revealed that new bone formed ectopically on the composite constructs, so that the 8-week explants of the composite sheets displayed radiological density similar to that of native bone. These results indicate that the strategy of using a combination of a cell sheet and coral particles has great potential for bone tissue engineering and repairing bone defects.

  2. Tape casting as a fabrication process for iron aluminide (FeAl) thin sheets

    Energy Technology Data Exchange (ETDEWEB)

    Mistler, R.E. [Richard E. Mistler Inc., Morrisville, PA (United States); Sikka, V.K. [ORNL, PO Box 2008, Oak Ridge, TN 37831 (United States); Scorey, C.R.; McKernan, J.E. [Ametek Inc., 21 Toelles Road, Wallingford, CT 06492 (United States); Hajaligol, M.R. [Research and Development Center, Philip Morris USA, PO Box 26581, Richmond, VA 23261 (United States)

    1998-12-31

    The conversion of iron aluminide powder into a slurry followed by tape casting into a green sheet was investigated. Casting parameters affecting green sheet properties were studied. Application of thermo-mechanical processing including sintering, cold rolling, annealing and heat treating resulted in sheets with a fine-grain structure at essentially 100% of theoretical density. The various microstructures developed throughout the process are described, along with tensile property measurements on the fully dense product. Differences in property with sheets made by other processes are explained, and it is demonstrated that tape casting is a viable method of making thin gauge sheets of iron aluminide with a wide range of compositions. (orig.) 9 refs.

  3. Analytical Evaluation of Fibre-Reinforced Plastic Corrugated Sheet

    OpenAIRE

    C. K. Gautam; R. C. Pathak

    1998-01-01

    Fibre-reinforced' composites playa lead role as advanced materials in modem day structures.This paper reports fabrication and testing offibre-reinforced corrugated sheet employing 4-point bend loading. An in-depth analysis has been carried out using ANSYS, a finite element method package.The theoretical results obtained are compared with the experimental values. The values ofboth inputsshowed similar results. conforming at a particular boundary condition. However, more similarexperiments "on ...

  4. Microchemistry in aluminium sheet production

    NARCIS (Netherlands)

    Lok, Z.J.

    2005-01-01

    The production of aluminium sheet alloys from as-cast ingots is a complex process, involving several rolling operations in combination with various thermal heat treatments. Through their influence on the alloy microchemistry and microstructure, these thermomechanical treatments are all aimed at cont

  5. Learning from Balance Sheet Visualization

    Science.gov (United States)

    Tanlamai, Uthai; Soongswang, Oranuj

    2011-01-01

    This exploratory study examines alternative visuals and their effect on the level of learning of balance sheet users. Executive and regular classes of graduate students majoring in information technology in business were asked to evaluate the extent of acceptance and enhanced capability of these alternative visuals toward their learning…

  6. Sports Injury Prevention Tip Sheet

    Science.gov (United States)

    ... Commemorative Giving Employment at AAP Advertise with AAP Advertising on AAP.org Advertising on AAP Journals & Publications AAP Mailing and eMail ... Help/Feedback a a a print email share Facebook Twitter 2017 Sports Injury Prevention Tip Sheet 3/ ...

  7. Application of Incremental Sheet Forming

    Directory of Open Access Journals (Sweden)

    Karbowski Krzysztof

    2015-12-01

    Full Text Available This paper describes some manufacturing aspects and an example of application of the Incremental Sheet Forming (ISF technology which was used for production of the craniofacial prosthesis. The brief description of prosthesis designing was presented as well. The main topic of the paper is comparison of milling and ISF technologies for preparing the tools for prosthesis thermoforming.

  8. High Blood Pressure Fact Sheet

    Science.gov (United States)

    ... High Blood Pressure Salt Cholesterol Million Hearts® WISEWOMAN High Blood Pressure Fact Sheet Language: English Español (Spanish) Recommend on ... time. High blood pressure is also called hypertension. High Blood Pressure in the United States Having high blood pressure ...

  9. Fact Sheets on Institutional Racism.

    Science.gov (United States)

    Foundation for Change, Inc., New York, NY.

    This fact sheet on institutional racism contains statistics on white control of the economy, health, housing, education, the media, and government. It also shows the oppression of minorities in these areas. The areas of wealth, the stock exchange, business, banks, unions, poverty, and unemployment, are discussed in terms of economy. Health matters…

  10. Fact Sheet: Vulnerable Young Children

    Science.gov (United States)

    Shaw, Evelyn, Comp.; Goode, Sue, Comp.

    2008-01-01

    This fact sheet provides data on infants, toddlers and young children who are experiencing high stress as a result of a number of risk factors specifically identified in the Individuals with Disabilities Education Improvement Act of 2004 (IDEA 2004), including substantiated abuse or neglect, foster care placement, homelessness, exposure to family…

  11. Fact Sheets on Institutional Racism.

    Science.gov (United States)

    Foundation for Change, Inc., New York, NY.

    This fact sheet on institutional racism contains statistics on white control of the economy, health, housing, education, the media, and government. It also shows the oppression of minorities in these areas. The areas of wealth, the stock exchange, business, banks, unions, poverty, and unemployment, are discussed in terms of economy. Health matters…

  12. Off-Balance Sheet Financing.

    Science.gov (United States)

    Adams, Matthew C.

    1998-01-01

    Examines off-balance sheet financing, the facilities use of outsourcing for selected needs, as a means of saving operational costs and using facility assets efficiently. Examples of using outside sources for energy supply and food services, as well as partnering with business for facility expansion are provided. Concluding comments address tax…

  13. Thermal and Mechanical Buckling Analysis of Hypersonic Aircraft Hat-Stiffened Panels With Varying Face Sheet Geometry and Fiber Orientation

    Science.gov (United States)

    Ko, William L.

    1996-01-01

    Mechanical and thermal buckling behavior of monolithic and metal-matrix composite hat-stiffened panels were investigated. The panels have three types of face-sheet geometry: Flat face sheet, microdented face sheet, and microbulged face sheet. The metal-matrix composite panels have three types of face-sheet layups, each of which is combined with various types of hat composite layups. Finite-element method was used in the eigenvalue extractions for both mechanical and thermal buckling. The thermal buckling analysis required both eigenvalue and material property iterations. Graphical methods of the dual iterations are shown. The mechanical and thermal buckling strengths of the hat-stiffened panels with different face-sheet geometry are compared. It was found that by just microdenting or microbulging of the face sheet, the axial, shear, and thermal buckling strengths of both types of hat-stiffened panels could be enhanced considerably. This effect is more conspicuous for the monolithic panels. For the metal-matrix composite panels, the effect of fiber orientations on the panel buckling strengths was investigated in great detail, and various composite layup combinations offering, high panel buckling strengths are presented. The axial buckling strength of the metal-matrix panel was sensitive to the change of hat fiber orientation. However, the lateral, shear, and thermal buckling strengths were insensitive to the change of hat fiber orientation.

  14. Brushed-on flexible supercapacitor sheets using a nanocomposite of polyaniline and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qiang; Yau, Siu-Tung [Department of Electrical and Computer Engineering, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115 (United States); Nayfeh, Munir H. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

    2010-11-01

    A simple, two-step method for constructing flexible sheets of supercapacitors is described. The construction is based on painting a sheet of flexible plastic electrolyte with a composite material made of a conducting polymer and carbon nanotubes. The total capacitance of the supercapacitor consists of pseudocapacitance produced by the polymer and electrical double-layer capacitance produced by carbon nanotubes. Stacks of the capacitor sheets were used to light up a system of three light-emitting diodes. The method suggests an inexpensive and potentially high-throughput approach for making flexible supercapacitors. (author)

  15. Brushed-on flexible supercapacitor sheets using a nanocomposite of polyaniline and carbon nanotubes

    Science.gov (United States)

    Liu, Qiang; Nayfeh, Munir H.; Yau, Siu-Tung

    A simple, two-step method for constructing flexible sheets of supercapacitors is described. The construction is based on painting a sheet of flexible plastic electrolyte with a composite material made of a conducting polymer and carbon nanotubes. The total capacitance of the supercapacitor consists of pseudocapacitance produced by the polymer and electrical double-layer capacitance produced by carbon nanotubes. Stacks of the capacitor sheets were used to light up a system of three light-emitting diodes. The method suggests an inexpensive and potentially high-throughput approach for making flexible supercapacitors.

  16. Ice-sheet configuration in the CMIP5/PMIP3 Last Glacial Maximum experiments

    Directory of Open Access Journals (Sweden)

    A. Abe-Ouchi

    2015-06-01

    Full Text Available We describe the creation of boundary conditions related to the presence of ice sheets, including ice sheet extent and height, ice shelf extent, and the distribution and altitude of ice-free land, at the Last Glacial Maximum (LGM for use in LGM experiments conducted as part of the fifth phase of the Coupled Modelling Intercomparison Project (CMIP5 and the third phase of the Palaeoclimate Modelling Intercomparison Project (PMIP3. The CMIP5/PMIP3 data sets were created from reconstructions made by three different groups, which were all obtained using a model-inversion approach but differ in the assumptions used in the modelling and in the type of data used as constraints. The ice sheet extent, and thus the albedo mask, for the Northern Hemisphere (NH does not vary substantially between the three individual data sources. The difference in the topography of the NH ice sheets is also moderate, and smaller than the differences between these reconstructions (and the resultant composite reconstruction and ice-sheet reconstructions used in previous generations of PMIP. Only two of the individual reconstructions provide information for Antarctica. The discrepancy between these two reconstructions is larger than the difference for the NH ice sheets although still less than the difference between the composite reconstruction and previous PMIP ice-sheet reconstructions. Differences in the climate response to the individual LGM reconstructions, and between these reconstructions and the CMIP5/PMIP3 composite, are largely confined to the ice-covered regions, but also extend over North Atlantic Ocean and Northern Hemisphere continents through atmospheric stationary waves. There are much larger differences in the climate response to the latest reconstructions (or the derived composite and ice-sheet reconstructions used in previous phases of PMIP.

  17. Graphene oxide sheets involved in vertically aligned zinc oxide nanowires for visible light photoinactivation of bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Nourmohammadi, Amin; Rahighi, Reza [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Akhavan, Omid, E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of); Moshfegh, Alireza [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2014-11-05

    Highlights: • Involvement of GO into the vertically aligned ZnO nanowires using electrophoretic deposition. • UV assisted photocatalytic reduction of the GO sheets involved in the ZnO nanowires. • Visible light photoinactivation of bacteria by the reduced graphene oxide/ZnO nanocomposite. - Abstract: Vertically aligned ZnO nanowires (NWs) hybridized with reduced graphene oxide sheets (rGO) were applied in efficient visible light photoinactivation of bacteria. To incorporate graphene oxide (GO) sheets within the NWs two different methods of drop-casting and electrophoretic deposition (EPD) were utilized. The EPD method yielded effective penetration of the positively charged GO sheets into the NWs to form a spider net-like structure, whereas the drop-casting method resulted in only a surface coverage of the GO sheets on top of the NWs. The electrical connection between the EPD-incorporated sheets and the NWs was checked by monitoring the electron transfer from UV-assisted photoexcited ZnO NWs into the GO sheets, during photocatalytic reduction of the sheets. The obtained rGO/ZnO composites were applied in visible light photoinactivation of Escherichia coli bacteria. The ZnO NWs could inactivate only ∼58% of the bacteria, while both drop-casting and EPD-prepared GO/ZnO composites exhibited strong antibacterial activities (especially the EPD sample with ∼99.5% photoinactivation), under visible light irradiation for 1 h. In fact, the visible light photocatalytic activity of the EPD-prepared GO/ZnO NW composite was found ∼1.9 and 6.2 folds of the activity of the GO/ZnO composite prepared by drop-casting method and the bare ZnO NWs.

  18. Global dynamics of the Antarctic ice sheet

    NARCIS (Netherlands)

    Oerlemans, J.

    2002-01-01

    The total mass budget of the Antarctic ice sheet is studied with a simple axi-symmetrical model. The ice-sheet has a parabolic profile resting on a bed that slopes linearly downwards from the centre of the ice sheet into the ocean. The mean ice velocity at the grounding line is assumed to be proport

  19. Immobilization of TiO2 nanofibers on reduced graphene sheets: Novel strategy in electrospinning.

    Science.gov (United States)

    Pant, Hem Raj; Adhikari, Surya Prasad; Pant, Bishweshwar; Joshi, Mahesh K; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2015-11-01

    A simple and efficient approach is developed to immobilize TiO2 nanofibers onto reduced graphene oxide (RGO) sheets. Here, TiO2 nanofiber-intercalated RGO sheets are readily produced by two-step procedure involving the use of electrospinning process to fabricate TiO2 precursor containing polymeric fibers on the surface of GO sheets, followed by simultaneous TiO2 nanofibers formation and GO reduction by calcinations. GO sheets deposited on the collector during electrospinning/electrospray can act as substrate on to which TiO2 precursor containing polymer nanofibers can be deposited which give TiO2 NFs doped RGO sheets on calcinations. Formation of corrugated structure cavities of graphene sheets decorated with TiO2 nanofibers on their surface demonstrates that our method constitutes an alternative top-down strategy toward fabricating verities of nanofiber-decorated graphene sheets. It was found that the synthesized TiO2/RGO composite revealed a remarkable increased in photocatalytic activity compared to pristine TiO2 nanofibers. Therefore, engineering of TiO2 nanofiber-intercalated RGO sheets using proposed facile technique can be considered a promising method for catalytic and other applications.

  20. Property Criteria for Automotive Al-Mg-Si Sheet Alloys

    Directory of Open Access Journals (Sweden)

    Ramona Prillhofer

    2014-07-01

    Full Text Available In this study, property criteria for automotive Al-Mg-Si sheet alloys are outlined and investigated in the context of commercial alloys AA6016, AA6005A, AA6063 and AA6013. The parameters crucial to predicting forming behavior were determined by tensile tests, bending tests, cross-die tests, hole-expansion tests and forming limit curve analysis in the pre-aged temper after various storage periods following sheet production. Roping tests were performed to evaluate surface quality, for the deployment of these alloys as an outer panel material. Strength in service was also tested after a simulated paint bake cycle of 20 min at 185 °C, and the corrosion behavior was analyzed. The study showed that forming behavior is strongly dependent on the type of alloy and that it is influenced by the storage period after sheet production. Alloy AA6016 achieves the highest surface quality, and pre-ageing of alloy AA6013 facilitates superior strength in service. Corrosion behavior is good in AA6005A, AA6063 and AA6016, and only AA6013 shows a strong susceptibility to intergranular corrosion. The results are discussed below with respect to the chemical composition, microstructure and texture of the Al-Mg-Si alloys studied, and decision-making criteria for appropriate automotive sheet alloys for specific applications are presented.

  1. Graphene: powder, flakes, ribbons, and sheets.

    Science.gov (United States)

    James, Dustin K; Tour, James M

    2013-10-15

    Graphene's unique physical and electrical properties (high tensile strength, Young's modulus, electron mobility, and thermal conductivity) have led to its nickname of "super carbon." Graphene research involves the study of several different physical forms of the material: powders, flakes, ribbons, and sheets and others not yet named or imagined. Within those forms, graphene can include a single layer, two layers, or ≤10 sheets of sp² carbon atoms. The chemistry and applications available with graphene depend on both the physical form of the graphene and the number of layers in the material. Therefore the available permutations of graphene are numerous, and we will discuss a subset of this work, covering some of our research on the synthesis and use of many of the different physical and layered forms of graphene. Initially, we worked with commercially available graphite, with which we extended diazonium chemistry developed to functionalize single-walled carbon nanotubes to produce graphitic materials. These structures were soluble in common organic solvents and were better dispersed in composites. We developed an improved synthesis of graphene oxide (GO) and explored how the workup protocol for the synthesis of GO can change the electronic structure and chemical functionality of the GO product. We also developed a method to remove graphene layers one-by-one from flakes. These powders and sheets of GO can serve as fluid loss prevention additives in drilling fluids for the oil industry. Graphene nanoribbons (GNRs) combine small width with long length, producing valuable electronic and physical properties. We developed two complementary syntheses of GNRs from multiwalled carbon nanotubes: one simple oxidative method that produces GNRs with some defects and one reductive method that produces GNRs that are less defective and more electrically conductive. These GNRs can be used in low-loss, high permittivity composites, as conductive reinforcement coatings on Kevlar

  2. Laminated exfoliated graphite composite-metal compositions for fuel cell flow field plate or bipolar plate applications

    Science.gov (United States)

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

    2014-05-20

    An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.

  3. Ice sheet hydrology from observations

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Peter (Dept. of Physical Geography and Quaternary Geology, Stockholm Univ-, Stockholm (Sweden))

    2010-11-15

    The hydrological systems of ice sheets are complex. Our view of the system is split, largely due to the complexity of observing the systems. Our basic knowledge of processes have been obtained from smaller glaciers and although applicable in general to the larger scales of the ice sheets, ice sheets contain features not observable on smaller glaciers due to their size. The generation of water on the ice sheet surface is well understood and can be satisfactorily modeled. The routing of water from the surface down through the ice is not complicated in terms of procat has been problematic is the way in which the couplings between surface and bed has been accomplished through a kilometer of cold ice, but with the studies on crack propagation and lake drainage on Greenland we are beginning to understand also this process and we know water can be routed through thick cold ice. Water generation at the bed is also well understood but the main problem preventing realistic estimates of water generation is lack of detailed information about geothermal heat fluxes and their geographical distribution beneath the ice. Although some average value for geothermal heat flux may suffice, for many purposes it is important that such values are not applied to sub-regions of significantly higher fluxes. Water generated by geothermal heat constitutes a constant supply and will likely maintain a steady system beneath the ice sheet. Such a system may include subglacial lakes as steady features and reconfiguration of the system is tied to time scales on which the ice sheet geometry changes so as to change pressure gradients in the basal system itself. Large scale re-organization of subglacial drainage systems have been observed beneath ice streams. The stability of an entirely subglacially fed drainage system may hence be perturbed by rapid ice flow. In the case of Antarctic ice streams where such behavior has been observed, the ice streams are underlain by deformable sediments. It is

  4. Ohm's law for a current sheet

    Science.gov (United States)

    Lyons, L. R.; Speiser, T. W.

    1985-01-01

    The paper derives an Ohm's law for single-particle motion in a current sheet, where the magnetic field reverses in direction across the sheet. The result is considerably different from the resistive Ohm's law often used in MHD studies of the geomagnetic tail. Single-particle analysis is extended to obtain a self-consistency relation for a current sheet which agrees with previous results. The results are applicable to the concept of reconnection in that the electric field parallel to the current is obtained for a one-dimensional current sheet with constant normal magnetic field. Dissipated energy goes directly into accelerating particles within the current sheet.

  5. Technology to Market Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-02-01

    This fact sheet is an overview of the Technology to Market subprogram at the U.S. Department of Energy SunShot Initiative. The SunShot Initiative’s Technology to Market subprogram builds on SunShot’s record of moving groundbreaking and early-stage technologies and business models through developmental phases to commercialization. Technology to Market targets two known funding gaps: those that occur at the prototype commercialization stage and those at the commercial scale-up stage.

  6. REINFORCED COMPOSITE PANEL

    DEFF Research Database (Denmark)

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  7. REINFORCED COMPOSITE PANEL

    DEFF Research Database (Denmark)

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  8. Reconnection in thin current sheets

    Science.gov (United States)

    Tenerani, Anna; Velli, Marco; Pucci, Fulvia; Rappazzo, A. F.

    2016-05-01

    It has been widely believed that reconnection is the underlying mechanism of many explosive processes observed both in nature and laboratory, but the question of reconnection speed and initial trigger have remained mysterious. How is fast magnetic energy release triggered in high Lundquist (S) and Reynolds (R) number plasmas?It has been shown that a tearing mode instability can grow on an ideal timescale, i.e., independent from the the Lundquist number, once the current sheet thickness becomes thin enough, or rather the inverse aspect ratio a/L reaches a scale a/L~S-1/3. As such, the latter provides a natural, critical threshold for current sheets that can be formed in nature before they disrupt in a few Alfvén time units. Here we discuss the transition to fast reconnection extended to simple viscous and kinetic models and we propose a possible scenario for the transition to explosive reconnection in high-Lundquist number plasmas, that we support with fully nonlinear numerical MHD simulations of a collapsing current sheet.

  9. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleishhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    2003-12-09

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  10. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2000-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr.ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  11. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, M.R.; Scorey, C.; Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.; Lilly, A.C. Jr.; German, R.M.

    2000-02-29

    A powder metallurgical process is disclosed of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as {<=}1% Cr, {>=}0.05% Zr{<=}2% Ti, {<=}2% Mo, {<=}1% Ni, {<=}0.75% C, {<=}0.1% B, {<=}1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, and/or {<=}3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 {mu}m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  12. MoN/氮化石墨烯复合物用作锂离子电容器电极材料的研究%Study on the MoN/Nitrogen-doped Graphene Sheets Composite for Lithium Ion Capacitor Electrode Materials

    Institute of Scientific and Technical Information of China (English)

    马文; 韩鹏献; 孔庆山; 张克军; 毕彩丰; 崔光磊

    2013-01-01

    以钼酸和氧化石墨烯为原料,正十二硫醇为还原剂,水热法反应后,在氨气气氛中高温氮化处理,制备出氮化钼/氮化石墨烯(MoN/NGS)复合材料.采用X射线衍射和扫描电子显微镜对材料进行了表征;采用循环伏安法、恒流充放电和电化学交流阻抗研究了该材料用于锂离子电容器的性能.结果表明,MoN纳米颗粒良好地分散在NGS表面和层间,在0.05 A/g的电流密度下质量比容量能达到422 F/g;经过900次充放电循环后,容量保持率在80%以上.当功率为3000 W/kg时,能量密度仍保持在32.5 Wh/kg.这归因于复合材料中的NGS提供了有效的导电网络,并且有效抑制了MoN颗粒的团聚,复合材料的网络结构更有利于离子的快速传输与扩散.%Molybdenum nitride/nitrogen-doped graphene sheets(MoN/NGS)composite was prepared via a simple hydrothermal method followed by calcination at 800℃ under ammonia atmosphere.The phase structure and morphology of samples were characterized by XRD and SEM.The electrochemical properties of composite electrodes were studied by performing cyclic voltammetry,galvanostatic charge and discharge,and electrochemical impedance spectroscopy test.The MoN/NGS electrode deliveres specific capacitance of 422 F/g at the current density of 0.05 A/g,and its capacitance retention remains more than 80% after 900 cycles.The energy density remains as high as 32.5 Wh/kg when the power density is 3000 W/kg.It should be noted that such improvement should be attributed not only to the presence of NGS in the composite offering an effective conducting network but also to the hybrid structure of MoN/NGS composite providing a favorable and fast ion transport and diffusion.

  13. Shock wave interactions with liquid sheets

    Science.gov (United States)

    Jeon, H.; Eliasson, V.

    2017-04-01

    Shock wave interactions with a liquid sheet are investigated by impacting planar liquid sheets of varying thicknesses with a planar shock wave. A square frame was designed to hold a rectangular liquid sheet, with a thickness of 5 or 10 mm, using plastic membranes and cotton wires to maintain the planar shape and minimize bulge. The flat liquid sheet, consisting of either water or a cornstarch and water mixture, was suspended in the test section of a shock tube. Incident shock waves with Mach numbers of M_s = 1.34 and 1.46 were considered. A schlieren technique with a high-speed camera was used to visualize the shock wave interaction with the liquid sheets. High-frequency pressure sensors were used to measure wave speed, overpressure, and impulse both upstream and downstream of the liquid sheet. Results showed that no transmitted shock wave could be observed through the liquid sheets, but compression waves induced by the shock-accelerated liquid coalesced into a shock wave farther downstream. A thicker liquid sheet resulted in a lower peak overpressure and impulse, and a cornstarch suspension sheet showed a higher attenuation factor compared to a water sheet.

  14. A New System for Understanding Mid-crustal Sheeted Complexes in a Tilted Crustal Section, Joshua Tree National Park, California

    Science.gov (United States)

    Ianno, A. J.; Paterson, S. R.

    2011-12-01

    The western portion of Joshua Tree National Park exposes a tilted crustal section through continental arc crust from 0-30 km. A significant portion of the middle crust is represented by Mesozoic, tabular, intrusive, igneous bodies ranging from 0.1 to 100 m in thickness. While these igneous bodies range in composition (gabbro to peraluminous granites), texture (equigranular to porphyritic), and grain size (very fine to coarse), patterns emerge between different regions of "sheeted complexes" that may be related to their emplacement and geochemical history. No consistent method of describing and comparing sheeted complexes exists in the literature, so we have developed a method of classifying sheeted complexes at Joshua Tree NP, which may be broadly applicable to all sheeted bodies. We classify these sheeted complexes using the terms homogeneous/heterogeneous and focused/defocused. A homogeneous sheeted complex generally contains magmas within a 10 wt% SiO2 range, although we are still testing the validity of this number. A focused sheeted complex has adjacent sheets or close spacing between sheets and Jurassic to Cretaceous sheeted complexes in western Joshua Tree NP. At Keys View, we observe a heterogeneous, spatially focused sheeted complex with 0.1-2 m thick sheets recording pressures indicating 15-22 km depth from top to bottom. Compositions range from gabbro to peraluminous granite, although tonalites-granodiorites and two-mica garnet granites are volumetrically dominant. A zone of elongate plutons (in map view) lying structurally above this could potentially be considered as a very thickly sheeted, homogeneous, focused sheeted complex and is composed of granodiorites, granites, and two-mica garnet granites. A more thickly sheeted (2-10 m), homogeneous, focused, sheeted granite complex with pressures indicating a depth of approximately 12 km is found along the northern edge of the park. The number of sheets decreases and the average thickness increases as this

  15. Fracture of composite-adhesive-composite systems

    Science.gov (United States)

    Ripling, E. J.; Santner, J. S.; Crosley, P. B.

    1984-01-01

    This program was undertaken to initiate the development of a test method for testing adhesive joints in metal-adhesive-composite systems. The uniform double cantilever beam (UDCB) and the width tapered beam (WTB) specimen geometries were evaluated for measuring Mode I fracture toughness in these systems. The WTB specimen is the preferred geometry in spite of the fact that it is more costly to machine than the UDCB specimen. The use of loading tabs attached to thin sheets of composites proved to be experimentally unsatisfactory. Consequently, a new system was developed to load thin sheets of adherends. This system allows for the direct measurement of displacement along the load line. In well made joints separation occurred between the plies rather than in the adhesive.

  16. 用碱矿渣胶凝材料粘贴碳纤维布加固组合梁受力性能试验研究%Experimental Research on Mechanical Properties of the Composite Beams Strengthened with Carbon Fiber Sheets Using Alkali-activated Slag Cementitious Materials

    Institute of Scientific and Technical Information of China (English)

    郑文忠; 朱晶; 陈伟宏

    2011-01-01

    At present, organic epoxy adhesives are usually used when strengthening concrete structures with carbon fiber sheets, but the softening points of organic adhesives are too low, most of which lie between 60℃ and 80℃. Because temperatures are high in summer, the surface temperatures of concrete bridge structures are often higher than the softening points of organic adhesives in some areas and the concrete structures strengthened with carbon fiber sheets using organic epoxy adhesives are difficult to meet heat resisting requirements.Therefore, the alkali-activated slag cementitious materials (AASCM) with the strength at 600℃ no lower than that at the normal atmospheric temperature were selected to paste carbon fiber sheets to strengthen 4 beams over the state of ultimate bearing capacity, and the mechanical properties of these 4 bonded prestressed truss concrete composite beams encased with circular steel tubes were studied by experiments. The test values of the flexural carrying capacity of these beams and the mid-span P-f curves presenting the two-fold line were obtained. On the basis of the test results, the calculation method of the flexural carrying capacity of the mentioned type of stiffened beams was presented in consideration of the influence of loading onto the original beams. The calculation formula of stiffness was set up, which is solved in good agreement with the test results.%目前粘贴碳纤维布加固混凝土结构多采用环氧类有机胶,但其软化点过低,多为60~80℃.夏季由于气温高,一些地区混凝土桥梁结构表面温度常超过环氧类有机胶的软化点,用环氧类有机胶粘贴碳纤维布加固的混凝土结构难以满足耐高温要求.为此,选用600℃时强度不低于常温强度的碱矿渣胶凝材料粘贴碳纤维布,对经历承载能力极限状态的4根黏结预应力内置圆钢管桁架混凝土组合梁进行加固并进行受力性能试验,获得加固梁的受弯承载力试验值和

  17. AI applications in sheet metal forming

    CERN Document Server

    Hussein, Hussein

    2017-01-01

    This book comprises chapters on research work done around the globe in the area of artificial intelligence (AI) applications in sheet metal forming. The first chapter offers an introduction to various AI techniques and sheet metal forming, while subsequent chapters describe traditional procedures/methods used in various sheet metal forming processes, and focus on the automation of those processes by means of AI techniques, such as KBS, ANN, GA, CBR, etc. Feature recognition and the manufacturability assessment of sheet metal parts, process planning, strip-layout design, selecting the type and size of die components, die modeling, and predicting die life are some of the most important aspects of sheet metal work. Traditionally, these activities are highly experience-based, tedious and time consuming. In response, researchers in several countries have applied various AI techniques to automate these activities, which are covered in this book. This book will be useful for engineers working in sheet metal industri...

  18. Path integral centroid molecular dynamics simulation of para-hydrogen sandwiched by graphene sheets

    Science.gov (United States)

    Minamino, Yuki; Kinugawa, Kenichi

    2016-11-01

    The carbon-hydrogen composite systems of para-hydrogen (p-H2) sandwiched by a couple of graphene sheets have been investigated by means of path integral centroid molecular dynamics simulations at 17 K. It has been shown that sandwiched hydrogen is liquid-like but p-H2 molecules are preferably adsorbed onto the graphene sheets because of attractive graphene-hydrogen interaction. The diffusion coefficient of p-H2 molecules in the direction parallel to the graphene sheets is comparable to that in pure liquid p-H2. There exists a characteristic mode of 140 cm-1 of the p-H2 molecules, attributed to adsorption-binding motion perpendicular to the graphene sheets.

  19. 40 CFR 124.8 - Fact sheet.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Fact sheet. 124.8 Section 124.8... DECISIONMAKING General Program Requirements § 124.8 Fact sheet. (Applicable to State programs, see §§ 123.25 (NPDES), 145.11 (UIC), 233.26 (404), and 271.14 (RCRA).) (a) A fact sheet shall be prepared for every...

  20. Development of Auto Sheets in Baosteel

    Institute of Scientific and Technical Information of China (English)

    LuJiangxin; WangLi

    2005-01-01

    The development trends of auto sheets in recent years are summarized with regard to the envirorunental regulations, market demands and strategy of the steel industry. The growth of domestic auto industry and demands for auto sheets are also briefed. The current status of development of Bake hardenable steel, Isotropic steel for outer panels and Transformation induced plasticity steel, dual phase steel for structural parts in Baosteel is introduced and the future of auto sheets in Baosteel is forecasted.

  1. Shape Optimization of Swimming Sheets

    Energy Technology Data Exchange (ETDEWEB)

    Wilkening, J.; Hosoi, A.E.

    2005-03-01

    The swimming behavior of a flexible sheet which moves by propagating deformation waves along its body was first studied by G. I. Taylor in 1951. In addition to being of theoretical interest, this problem serves as a useful model of the locomotion of gastropods and various micro-organisms. Although the mechanics of swimming via wave propagation has been studied extensively, relatively little work has been done to define or describe optimal swimming by this mechanism.We carry out this objective for a sheet that is separated from a rigid substrate by a thin film of viscous Newtonian fluid. Using a lubrication approximation to model the dynamics, we derive the relevant Euler-Lagrange equations to optimize swimming speed and efficiency. The optimization equations are solved numerically using two different schemes: a limited memory BFGS method that uses cubic splines to represent the wave profile, and a multi-shooting Runge-Kutta approach that uses the Levenberg-Marquardt method to vary the parameters of the equations until the constraints are satisfied. The former approach is less efficient but generalizes nicely to the non-lubrication setting. For each optimization problem we obtain a one parameter family of solutions that becomes singular in a self-similar fashion as the parameter approaches a critical value. We explore the validity of the lubrication approximation near this singular limit by monitoring higher order corrections to the zeroth order theory and by comparing the results with finite element solutions of the full Stokes equations.

  2. A technique for generating consistent ice sheet initial conditions for coupled ice-sheet/climate models

    Directory of Open Access Journals (Sweden)

    J. G. Fyke

    2013-04-01

    Full Text Available A new technique for generating ice sheet preindustrial 1850 initial conditions for coupled ice-sheet/climate models is developed and demonstrated over the Greenland Ice Sheet using the Community Earth System Model (CESM. Paleoclimate end-member simulations and ice core data are used to derive continuous surface mass balance fields which are used to force a long transient ice sheet model simulation. The procedure accounts for the evolution of climate through the last glacial period and converges to a simulated preindustrial 1850 ice sheet that is geometrically and thermodynamically consistent with the 1850 preindustrial simulated CESM state, yet contains a transient memory of past climate that compares well to observations and independent model studies. This allows future coupled ice-sheet/climate projections of climate change that include ice sheets to integrate the effect of past climate conditions on the state of the Greenland Ice Sheet, while maintaining system-wide continuity between past and future climate simulations.

  3. Nuclear Data Sheets for A = 79

    Science.gov (United States)

    Singh, Balraj

    2016-07-01

    Nuclear spectroscopic information for known nuclides of mass number 79 (Ni,Cu,Zn,Ga,Ge,As,Se,Br,Kr,Rb, Sr,Y,Zr) has been evaluated and presented together with adopted energies, Jπ, and decay modes of levels in these nuclei. No data are yet available for excited states in 79Ni, 79Cu and 79Zr. The half-life of 79Se, a nuclide of importance in reactor-irradiated fuel composition has been measured by several independent groups and reported in a number of publications after 1995, and seems to be converging to a narrow margin of experimental values. These measurements were likely prompted by a recommendation made in the 1993 update of A = 79 nuclides (1993Si28), that since a 1949PaZZ report, there had been no measurement until 1993, and that based on simulation studies by 1993HeZW, the value listed in 1949PaZZ, and cited in all data tables and charts for 44 years, was quite likely in error, being too low by a factor of 10. According to conclusions in recent papers such as 2014Do20, there is still room for improvement in the measurement of this half-life, and further experiments are expected. This evaluation supersedes earlier Nuclear Data Sheets for A = 79 (2002Si13,1993Si28, 1982Si21,1975Ur03).

  4. Gyrophase bunched ions in the plasma sheet

    Science.gov (United States)

    Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu; Huang, Chaoyan

    2017-01-01

    Gyrophase bunched ions were first detected in the upstream region of the Earth's bow shock in the early 1980s which is formed by the microphysical process associated with reflected solar wind ions at the bow shock. Inside the magnetosphere, the results of computer simulations demonstrated that nonlinear wave-particle interaction can also result in the gyrophase bunching of particles. However, to date direct observations barely exist regarding this issue occurred inside the magnetosphere. In this paper, we report for the first time an event of gyrophase bunched ions observed in the near-Earth plasma sheet. The nongyrotropic distributions of ions were closely accompanied with the electromagnetic waves at the oxygen cyclotron frequency. The phase of bunched ions and the phase of waves mainly have very narrow phase differences (helicity with respect to the propagation direction, which agrees with the characteristic of electromagnetic ion cyclotron waves. The observation of O+ ions composition suggests that the oxygen band waves are excited due to the enhancements of the O+ ion density. This study suggests that the gyrophase bunching is a significant nonlinear effect that exists not only in the bow shock but also in the inner magnetosphere.

  5. Meltwater export of prokaryotic cells from the Greenland ice sheet.

    Science.gov (United States)

    Cameron, Karen A; Stibal, Marek; Hawkings, Jon R; Mikkelsen, Andreas B; Telling, Jon; Kohler, Tyler J; Gözdereliler, Erkin; Zarsky, Jakub D; Wadham, Jemma L; Jacobsen, Carsten S

    2017-02-01

    Microorganisms are flushed from the Greenland Ice Sheet (GrIS) where they may contribute towards the nutrient cycling and community compositions of downstream ecosystems. We investigate meltwater microbial assemblages as they exit the GrIS from a large outlet glacier, and as they enter a downstream river delta during the record melt year of 2012. Prokaryotic abundance, flux and community composition was studied, and factors affecting community structures were statistically considered. The mean concentration of cells exiting the ice sheet was 8.30 × 10(4) cells mL(-1) and we estimate that ∼1.02 × 10(21) cells were transported to the downstream fjord in 2012, equivalent to 30.95 Mg of carbon. Prokaryotic microbial assemblages were dominated by Proteobacteria, Bacteroidetes, and Actinobacteria. Cell concentrations and community compositions were stable throughout the sample period, and were statistically similar at both sample sites. Based on our observations, we argue that the subglacial environment is the primary source of the river-transported microbiota, and that cell export from the GrIS is dependent on discharge. We hypothesise that the release of subglacial microbiota to downstream ecosystems will increase as freshwater flux from the GrIS rises in a warming world. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  6. A statistical study on the correlations between plasma sheet and solar wind based on DSP explorations

    Directory of Open Access Journals (Sweden)

    G. Q. Yan

    2005-11-01

    Full Text Available By using the data of two spacecraft, TC-1 and ACE (Advanced Composition Explorer, a statistical study on the correlations between plasma sheet and solar wind has been carried out. The results obtained show that the plasma sheet at geocentric distances of about 9~13.4 Re has an apparent driving relationship with the solar wind. It is found that (1 there is a positive correlation between the duskward component of the interplanetary magnetic field (IMF and the duskward component of the geomagnetic field in the plasma sheet, with a proportionality constant of about 1.09. It indicates that the duskward component of the IMF can effectively penetrate into the near-Earth plasma sheet, and can be amplified by sunward convection in the corresponding region at geocentric distances of about 9~13.4 Re; (2 the increase in the density or the dynamic pressure of the solar wind will generally lead to the increase in the density of the plasma sheet; (3 the ion thermal pressure in the near-Earth plasma sheet is significantly controlled by the dynamic pressure of solar wind; (4 under the northward IMF condition, the ion temperature and ion thermal pressure in the plasma sheet decrease as the solar wind speed increases. This feature indicates that plasmas in the near-Earth plasma sheet can come from the magnetosheath through the LLBL. Northward IMF is one important condition for the transport of the cold plasmas of the magnetosheath into the plasma sheet through the LLBL, and fast solar wind will enhance such a transport process.

  7. An ice sheet model validation framework for the Greenland ice sheet

    NARCIS (Netherlands)

    Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.; Howat, Ian M.; Neumann, Thomas; Saba, Jack; Tezaur, Irina; Guerber, Jeffrey; Chambers, Don P.; Evans, Katherine J.; Kennedy, Joseph H.; Lenaerts, Jan; Lipscomb, William H.; Perego, Mauro; Salinger, Andrew G.; Tuminaro, Raymond S.; Van Den Broeke, Michiel R.; Nowicki, Sophie M J

    2017-01-01

    We propose a new ice sheet model validation framework - the Cryospheric Model Comparison Tool (CmCt) - that takes advantage of ice sheet altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice sheet. We use realistic

  8. ISSM: Ice Sheet System Model

    Science.gov (United States)

    Larour, Eric; Schiermeier, John E.; Seroussi, Helene; Morlinghem, Mathieu

    2013-01-01

    In order to have the capability to use satellite data from its own missions to inform future sea-level rise projections, JPL needed a full-fledged ice-sheet/iceshelf flow model, capable of modeling the mass balance of Antarctica and Greenland into the near future. ISSM was developed with such a goal in mind, as a massively parallelized, multi-purpose finite-element framework dedicated to ice-sheet modeling. ISSM features unstructured meshes (Tria in 2D, and Penta in 3D) along with corresponding finite elements for both types of meshes. Each finite element can carry out diagnostic, prognostic, transient, thermal 3D, surface, and bed slope simulations. Anisotropic meshing enables adaptation of meshes to a certain metric, and the 2D Shelfy-Stream, 3D Blatter/Pattyn, and 3D Full-Stokes formulations capture the bulk of the ice-flow physics. These elements can be coupled together, based on the Arlequin method, so that on a large scale model such as Antarctica, each type of finite element is used in the most efficient manner. For each finite element referenced above, ISSM implements an adjoint. This adjoint can be used to carry out model inversions of unknown model parameters, typically ice rheology and basal drag at the ice/bedrock interface, using a metric such as the observed InSAR surface velocity. This data assimilation capability is crucial to allow spinning up of ice flow models using available satellite data. ISSM relies on the PETSc library for its vectors, matrices, and solvers. This allows ISSM to run efficiently on any parallel platform, whether shared or distrib- ISSM: Ice Sheet System Model NASA's Jet Propulsion Laboratory, Pasadena, California uted. It can run on the largest clusters, and is fully scalable. This allows ISSM to tackle models the size of continents. ISSM is embedded into MATLAB and Python, both open scientific platforms. This improves its outreach within the science community. It is entirely written in C/C++, which gives it flexibility in its

  9. Damage Tolerance of Sandwich Plates With Debonded Face Sheets

    Science.gov (United States)

    Sankar, Bhavani V.

    2001-01-01

    A nonlinear finite element analysis was performed to simulate axial compression of sandwich beams with debonded face sheets. The load - end-shortening diagrams were generated for a variety of specimens used in a previous experimental study. The energy release rate at the crack tip was computed using the J-integral, and plotted as a function of the load. A detailed stress analysis was performed and the critical stresses in the face sheet and the core were computed. The core was also modeled as an isotropic elastic-perfectly plastic material and a nonlinear post buckling analysis was performed. A Graeco-Latin factorial plan was used to study the effects of debond length, face sheet and core thicknesses, and core density on the load carrying capacity of the sandwich composite. It has been found that a linear buckling analysis is inadequate in determining the maximum load a debonded sandwich beam can carry. A nonlinear post-buckling analysis combined with an elastoplastic model of the core is required to predict the compression behavior of debonded sandwich beams.

  10. Concentrating Solar Power Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    None

    2015-12-01

    This fact sheet is an overview of the Concentrating Solar Power (CSP) subprogram at the U.S. Department of Energy SunShot Initiative. CSP is a dispatchable, renewable energy option that uses mirrors to focus and concentrate sunlight onto a receiver, from which a heat transfer fluid carries the intense thermal energy to a power block to generate electricity. CSP systems can store solar energy to be used when the sun is not shining. It will help meet the nation’s goal of making solar energy fully cost-competitive with other energy sources by the end of the decade. Worldwide, CSP activity is rapidly scaling, with approximately 10 gigawatts (GW) in various stages of operation or development. In the United States alone, nearly 2 GW of CSP are in operation.

  11. 基于对氨基苯磺酸功能化石墨烯/Nafion复合膜修饰电极的咖啡因电化学传感器%Caffeine biosensor based on sulfanilic acid functionalized graphene sheets/Nafion composite film modified electrode

    Institute of Scientific and Technical Information of China (English)

    杨武; 方芳; 郭昊; 牛秀丽; 刘婧

    2014-01-01

    The sulfanilic acid functionalized graphene sheets (AS-GS ) and methanol solution of 0.1%nafion are used to fabricate a new type of composite film modified electrode . T he modified electrode is characterized by scanning electron microscope (SEM ) . The electrochemical behaviors and kinetic properties of caffeine on the modified electrode are investigated by cyclic voltammetry (CV ) and the differential pulse voltammetry(DPV) . The modified electrode displays excellent electrochemical catalytic activities toward the oxidation of caffeine under the optimum condition . The peak current is linearly dependent on the CAF concentrations in the range of 1~500 μmol·L -1 with the detection limit (S/N=3) of 5.31 × 10-7 mol·L -1 . In addition , the composition film of AS-GS/Nafion modified electrode show s high sensitivity ,favorable stability and reproducibility .Moreover ,AS-GS/Nafion modified electrode has been applied to the quick determination of CAF in the cola and functional beverage .%以对氨基苯磺酸功能化石墨烯(AS-GS)和0.1% Nafion的甲醇溶液制备了一种新型的复合膜修饰电极.采用扫描电镜(SEM)对修饰电极进行了表征,并利用循环伏安法(CV)和微分脉冲伏安法(DPV)研究了咖啡因(CAF)在修饰电极上的电化学行为.在最优条件下,修饰电极对咖啡因的氧化有良好的电催化活性,氧化峰电流与咖啡因浓度在1~500μmol·L -1范围内呈良好的线性关系,检测限为5.31×10-7 mol·L -1(S/N=3).此外, AS-GS/Nafion复合膜修饰电极具有较高的灵敏性,较好的稳定性和重现性,可用于可乐和功能性饮料中咖啡因含量的快速检测.

  12. Antibubbles and fine cylindrical sheets of air

    NARCIS (Netherlands)

    Beilharz, D.; Guyon, A.; Li, E.Q.; Thoraval, Marie-Jean; Thoroddsen, S.T.

    2015-01-01

    Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a

  13. Molding cork sheets to complex shapes

    Science.gov (United States)

    Sharpe, M. H.; Simpson, W. G.; Walker, H. M.

    1977-01-01

    Partially cured cork sheet is easily formed to complex shapes and then final-cured. Temperature and pressure levels required for process depend upon resin system used and final density and strength desired. Sheet can be bonded to surface during final cure, or can be first-formed in mold and bonded to surface in separate step.

  14. Fact Sheets on Pesticides in Schools.

    Science.gov (United States)

    National Coalition against the Misuse of Pesticides, Washington, DC.

    This document consists of a collection of fact sheets about the use of pesticides in schools and how to reduce it. The sheets are: (1) "Alternatives to Using Pesticides in Schools: What Is Integrated Pest Management?"; (2) "Health Effects of 48 Commonly Used Pesticides in Schools"; (3) "The Schooling of State Pesticide Laws--2002 Update: A Review…

  15. Clouds enhance Greenland ice sheet meltwater runoff

    NARCIS (Netherlands)

    Van Tricht, K.; Lhermitte, S.; Lenaerts, J. T M|info:eu-repo/dai/nl/314850163; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B.|info:eu-repo/dai/nl/370612345; Van Den Broeke, M. R.|info:eu-repo/dai/nl/073765643; Turner, D. D.; Van Lipzig, N. P M

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative

  16. 16 CFR 460.13 - Fact sheets.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Fact sheets. 460.13 Section 460.13 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES LABELING AND ADVERTISING OF HOME INSULATION § 460.13 Fact sheets. If you are a manufacturer, you must give retailers and installers...

  17. Dylan Pritchett, Storyteller. Cue Sheet for Students.

    Science.gov (United States)

    Evans, Karen L. B.

    Designed to be used before and after attending a storytelling performance by Dylan Pritchett, this cue sheet presents information about the performance and suggests activities that can be done with classmates, friends, or family members. The cue sheet discusses where and why people tell stories, what makes a story good for telling, what makes a…

  18. Balance velocities of the Greenland ice sheet

    DEFF Research Database (Denmark)

    Joughin, I.; Fahnestock, M.; Ekholm, Simon;

    1997-01-01

    We present a map of balance velocities for the Greenland ice sheet. The resolution of the underlying DEM, which was derived primarily from radar altimetery data, yields far greater detail than earlier balance velocity estimates for Greenland. The velocity contours reveal in striking detail......, the balance map is useful for ice-sheet modelling, mass balance studies, and field planning....

  19. Steel Sheet Pile Walls in Soft Soil

    NARCIS (Netherlands)

    Kort, D.A.

    2002-01-01

    For almost a century, steel sheet pile walls are applied worldwide as earth retaining structures for excavations and quay walls. Within the framework of the development of European structural codes for Civil Engineering works, the Eurocodes, Eurocode 3 Part 5 for design of steel sheet pile walls was

  20. Clouds enhance Greenland ice sheet meltwater runoff

    NARCIS (Netherlands)

    Van Tricht, K.; Lhermitte, S.; Lenaerts, J. T M|info:eu-repo/dai/nl/314850163; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B.|info:eu-repo/dai/nl/370612345; Van Den Broeke, M. R.|info:eu-repo/dai/nl/073765643; Turner, D. D.; Van Lipzig, N. P M

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative

  1. The Elementary Marine Ice Sheet Model (EMISM)

    Science.gov (United States)

    Pattyn, Frank

    2015-04-01

    Ice sheet models become more and more components of global climate system modelling instead of stand-alone features to study cryospheric processes. Full coupling of ice sheet models to atmospheric and ocean models requires a standard for ice sheet models, and more precisely for marine ice sheet models, where complex feedbacks between ice and ocean, such as marine ice sheet instability, and the atmosphere, such as the elevation-mass balance feedback, operate at different time scales. Recent model intercomparisons (e.g., SeaRISE, MISMIP) have shown that basic requirements for marine ice sheet models are still lacking and that the complexity of many ice sheet models is focused on processes that are either not well captured numerically (spatial resolution issue) or are of secondary importance compared to the essential features of marine ice sheet dynamics. Here, we propose a new and fast computing ice sheet model, devoid of most complexity, but capturing the essential feedbacks when coupled to ocean or atmospheric models. Its computational efficiency guarantees to easily tests its advantages as well as limits through ensemble modelling. EMISM (Elementary Marine Ice Sheet Model) is a vertically integrated ice sheet model based on the Shallow-Ice Approximation extended a Weertman sliding law. Although vertically integrated, thermomechanical coupling is ensured through a simplified representation of ice sheet thermodynamics based on an analytical solution of the vertical temperature profile, enhanced with strain heating. The marine boundary is represented by a parameterized flux condition similar to Pollard & Deconto (2012), based on Schoof (2007). A simplified ice shelf is added to account for buttressing of ice shelves in this parameterization. The ice sheet model is solved on a finite difference grid and special care is taken to its numerical efficiency and stability. While such model has a series of (known) deficiencies with respect to short time effects, its overall

  2. The dependence of sheet erosion velocity on slope angle

    Directory of Open Access Journals (Sweden)

    Chernyshev Sergey Nikolaevich

    2014-09-01

    Full Text Available The article presents a method for estimating the erosion velocity on forested natural area. As a research object for testing the methodology the authors selected Neskuchny Garden - a city Park on the Moskva river embankment, named after the cognominal Palace of Catherine's age. Here, an almost horizontal surface III of the Moskva river terrace above the flood-plain is especially remarkable, accentuated by the steep sides of the ravine parallel to St. Andrew's, but short and nameless. The crests of the ravine sides are sharp, which is the evidence of its recent formation, but the old trees on the slopes indicate that it has not been growing for at least 100 years. Earlier Russian researchers defined vertical velocity of sheet erosion for different regions and slopes with different parent (in relation to the soil rocks. The comparison of the velocities shows that climatic conditions, in the first approximation, do not have a decisive influence on the erosion velocity of silt loam soils. The velocities on the shores of Issyk-Kul lake and in Moscow proved to be the same. But the composition of the parent rocks strongly affects the sheet erosion velocity. Even low-strength rock material reduces the velocity by times. Phytoindication method gives a real, physically explainable sheet erosion velocities. The speed is rather small but it should be considered when designing long-term structures on the slopes composed of dispersive soils. On the slopes composed of rocky soils sheet erosion velocity is so insignificant that it shouldn't be taken into account when designing. However, there may be other geological processes, significantly disturbing the stability of slopes connected with cracks.

  3. Folded Sheet Versus Transparent Sheet Models for Human Symmetry Judgments

    Directory of Open Access Journals (Sweden)

    Jacques Ninio

    2011-07-01

    Full Text Available As a contribution to the mysteries of human symmetry perception, reaction time data were collected on the detection of symmetry or repetition violations, in the context of short term visual memory studies. The histograms for reaction time distributions are rather narrow in the case of symmetry judgments. Their analysis was performed in terms of a simple kinetic model of a mental process in two steps, a slow one for the construction of the representation of the images to be compared, and a fast one, in the 50 ms range, for the decision. There was no need for an additional ‘mental rotation’ step. Symmetry seems to facilitate the construction step. I also present here original stimuli showing a color equalization effect across a symmetry axis, and its counterpart in periodic patterns. According to a “folded sheet model”, when a shape is perceived, the brain automatically constructs a mirror-image representation of the shape. Based in part on the reaction time analysis, I present here an alternative “transparent sheet” model in which the brain constructs a single representation, which can be accessed from two sides, thus generating simultaneously a pattern and its mirror-symmetric partner. Filtering processes, implied by current models of symmetry perception could intervene at an early stage, by nucleating the propagation of similar perceptual groupings in the two symmetric images.

  4. Increased Tensile Strength of Carbon Nanotube Yarns and Sheets through Chemical Modification and Electron Beam Irradiation

    Science.gov (United States)

    Miller, Sandi G.; Williams, Tiffany S.; Baker, James S.; Sola, Francisco; Lebron-Colon, Marisabel; McCorkle, Linda S.; Wilmoth, Nathan G.; Gaier, James; Chen, Michelle; Meador, Michael A.

    2014-01-01

    The inherent strength of individual carbon nanotubes offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of carbon nanotube (CNT) forms such as yarns and sheets has addressed early nanocomposite limitations with respect to nanotube dispersion and loading; and has pushed the technology toward structural composite applications. However, the high tensile strength of an individual CNT has not directly translated to macro-scale CNT forms where bulk material strength is limited by inter-tube electrostatic attraction and slippage. The focus of this work was to assess post processing of CNT sheet and yarn to improve the macro-scale strength of these material forms. Both small molecule functionalization and e-beam irradiation was evaluated as a means to enhance tensile strength and Youngs modulus of the bulk CNT material. Mechanical testing results revealed a tensile strength increase in CNT sheets by 57 when functionalized, while an additional 48 increase in tensile strength was observed when functionalized sheets were irradiated; compared to unfunctionalized sheets. Similarly, small molecule functionalization increased yarn tensile strength up to 25, whereas irradiation of the functionalized yarns pushed the tensile strength to 88 beyond that of the baseline yarn.

  5. Key technologies for manufacturing and processing sheet materials: A global perspective

    Science.gov (United States)

    Demeri, Mahmoud Y.

    2001-02-01

    Modern industrial technologies continue to seek new materials and processes to produce products that meet design and functional requirements. Sheet materials made from ferrous and non-ferrous metals, laminates, composites, and reinforced plastics constitute a large percentage of today’s products, components, and systems. Major manufacturers of sheet products include automotive, aerospace, appliance, and food-packaging industries. The Second Global Symposium on Innovations in Materials Processing & Manufacturing: Sheet Materials is organized to provide a forum for presenting advances in sheet processing and manufacturing by worldwide researchers and engineers from industrial, research, and academic centers. The symposium, sponsored by the TMS Materials Processing & Manufacturing Division (MPMD), was planned for the 2001 TMS Annual Meeting, New Orleans, Louisiana, February 11 15, 2001. This article is a review of key papers submitted for publication in the concurrent volume. The selected papers present significant developments in the rapidly expanding areas of advanced sheet materials, innovative forming methods, industrial applications, primary and secondary processing, composite processing, and numerical modeling of manufacturing processes.

  6. Composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  7. Composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Kaschmitter, James L. (Pleasanton, CA)

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  8. Addition of Adipose-Derived Stem Cells to Mesenchymal Stem Cell Sheets Improves Bone Formation at an Ectopic Site

    Directory of Open Access Journals (Sweden)

    Zhifa Wang

    2016-02-01

    Full Text Available To determine the effect of adipose-derived stem cells (ADSCs added to bone marrow-derived mesenchymal stem cell (MSC sheets on bone formation at an ectopic site. We isolated MSCs and ADSCs from the same rabbits. We then prepared MSC sheets for implantation with or without ADSCs subcutaneously in the backs of severe combined immunodeficiency (SCID mice. We assessed bone formation at eight weeks after implantation by micro-computed tomography and histological analysis. In osteogenic medium, MSCs grew to form multilayer sheets containing many calcium nodules. MSC sheets without ADSCs formed bone-like tissue; although neo-bone and cartilage-like tissues were sparse and unevenly distributed by eight weeks after implantation. In comparison, MSC sheets with ADSCs promoted better bone regeneration as evidenced by the greater density of bone, increased mineral deposition, obvious formation of blood vessels, large number of interconnected ossified trabeculae and woven bone structures, and greater bone volume/total volume within the composite constructs. Our results indicate that although sheets of only MSCs have the potential to form tissue engineered bone at an ectopic site, the addition of ADSCs can significantly increase the osteogenic potential of MSC sheets. Thus, the combination of MSC sheets with ADSCs may be regarded as a promising therapeutic strategy to stimulate bone regeneration.

  9. Computer-aided light sheet flow visualization

    Science.gov (United States)

    Stacy, Kathryn; Severance, Kurt; Childers, Brooks A.

    1993-01-01

    A computer-aided flow visualization process has been developed to analyze video images acquired from rotating and translating light sheet visualization systems. The computer process integrates a mathematical model for image reconstruction, advanced computer graphics concepts, and digital image processing to provide a quantitative and visual analysis capability. The image reconstruction model, based on photogrammetry, uses knowledge of the camera and light sheet locations and orientations to project two-dimensional light sheet video images into three-dimensional space. A sophisticated computer visualization package, commonly used to analyze computational fluid dynamics (CFD) data sets, was chosen to interactively display the reconstructed light sheet images, along with the numerical surface geometry for the model or aircraft under study. A description is provided of the photogrammetric reconstruction technique, and the image processing and computer graphics techniques and equipment. Results of the computer aided process applied to both a wind tunnel translating light sheet experiment and an in-flight rotating light sheet experiment are presented. The capability to compare reconstructed experimental light sheet images and CFD solutions in the same graphics environment is also demonstrated.

  10. Size-dependent deformation behavior of nanocrystalline graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhi [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Huang, Yuhong [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, Shaanxi (China); Ma, Fei, E-mail: mafei@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Sun, Yunjin [Faculty of Food Science and Engineering, Beijing University of Agriculture, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Laboratory of Food Quality and Safety, Beijing 102206 (China); Xu, Kewei, E-mail: kwxu@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Opt-electronic Engineering, Xi’an University of Arts and Science, Xi’an 710065, Shaanxi (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-08-15

    Highlights: • MD simulation is conducted to study the deformation of nanocrystalline graphene. • Unexpectedly, the elastic modulus decreases with the grain size considerably. • But the fracture stress and strain are nearly insensitive to the grain size. • A composite model with grain domains and GBs as two components is suggested. - Abstract: Molecular dynamics (MD) simulation is conducted to study the deformation behavior of nanocrystalline graphene sheets. It is found that the graphene sheets have almost constant fracture stress and strain, but decreased elastic modulus with grain size. The results are different from the size-dependent strength observed in nanocrystalline metals. Structurally, the grain boundaries (GBs) become a principal component in two-dimensional materials with nano-grains and the bond length in GBs tends to be homogeneously distributed. This is almost the same for all the samples. Hence, the fracture stress and strain are almost size independent. As a low-elastic-modulus component, the GBs increase with reducing grain size and the elastic modulus decreases accordingly. A composite model is proposed to elucidate the deformation behavior.

  11. Origin of the warped heliospheric current sheet

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, J.M.; Hoeksema, J.T.; Scherrer, P.H.

    1980-08-01

    The warped heliospheric current sheet for early 1976 is calculated from the observed photospheric magnetic field by a potential field method. Comparisons with measurements of the interplanetary magnetic field polarity for early 1976 obtained at several locations in the heliosphere by Helios 1, Helios 2, Pioneer 11, and at the earth show a rather detailed agreement between the computed current sheet and the observations. It appears that the large-scale structure of the warped heliospheric current sheet is determined by the structure of the photospheric magnetic field and that ballerina skirt effects may add small-scale ripples.

  12. Origin of the warped heliospheric current sheet

    Science.gov (United States)

    Wilcox, J. M.; Hoeksema, J. T.; Scherrer, P. H.

    1980-08-01

    The warped heliospheric current sheet for early 1976 is calculated from the observed photospheric magnetic field by a potential field method. Comparisons with measurements of the interplanetary magnetic field polarity for early 1976 obtained at several locations in the heliosphere by Helios 1, Helios 2, Pioneer 11, and at the earth show a rather detailed agreement between the computed current sheet and the observations. It appears that the large-scale structure of the warped heliospheric current sheet is determined by the structure of the photospheric magnetic field and that 'ballerina skirt' effects may add small scale ripples.

  13. Bifurcation of Jovian magnetotail current sheet

    Directory of Open Access Journals (Sweden)

    P. L. Israelevich

    2006-07-01

    Full Text Available Multiple crossings of the magnetotail current sheet by a single spacecraft give the possibility to distinguish between two types of electric current density distribution: single-peaked (Harris type current layer and double-peaked (bifurcated current sheet. Magnetic field measurements in the Jovian magnetic tail by Voyager-2 reveal bifurcation of the tail current sheet. The electric current density possesses a minimum at the point of the Bx-component reversal and two maxima at the distance where the magnetic field strength reaches 50% of its value in the tail lobe.

  14. Dynamics of laterally confined marine ice sheets

    OpenAIRE

    Kowal, Katarzyna N.; Pegler, Samuel S.; Worster, M. Grae

    2016-01-01

    This is the author accepted manuscript. The final version is available from Cambridge University Press via http://dx.doi.org/10.1017/jfm.2016.37 We present an experimental and theoretical study of the dynamics of laterally confined marine ice sheets in the natural limit in which the long, narrow channel into which they flow is wider than the depth of the ice. A marine ice sheet comprises a grounded ice sheet in contact with bedrock that floats away from the bedrock at a ‘grounding line’ t...

  15. Photobiology Research Laboratory (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2012-06-01

    This fact sheet provides information about Photobiology Research Laboratory capabilities and applications at NREL. The photobiology group's research is in four main areas: (1) Comprehensive studies of fuel-producing photosynthetic, fermentative, and chemolithotrophic model microorganisms; (2) Characterization and engineering of redox enzymes and proteins for fuel production; (3) Genetic and pathway engineering of model organisms to improve production of hydrogen and hydrocarbon fuels; and (4) Studies of nanosystems using biological and non-biological materials in hybrid generation. NREL's photobiology research capabilities include: (1) Controlled and automated photobioreactors and fermenters for growing microorganisms under a variety of environmental conditions; (2) High-and medium-throughput screening of H{sub 2}-producing organisms; (3) Homologous and heterologous expression, purification, and biochemical/biophysical characterization of redox enzymes and proteins; (4) Qualitative and quantitative analyses of gases, metabolites, carbohydrates, lipids, and proteins; (5) Genetic and pathway engineering and development of novel genetic toolboxes; and (6) Design and spectroscopic characterization of enzyme-based biofuel cells and energy conversion nanodevices.

  16. Central bank balance sheet concerns and credible optimal escape from the Liquidity trap

    OpenAIRE

    Mendes, Arthur Galego

    2001-01-01

    I show that when a central bank is financially independent from the treasury and has balance sheet concerns, an increase in the size or a change in the composition of the central bank's balance sheet (quantitative easing) can serve as a commitment device in a liquidity trap scenario. In particular, when the short-term interest rate is up against the zero lower bound, an open market operation by the central bank that involves purchases of long-term bonds can help mitigate the ...

  17. Central bank balance sheet concerns and credible optimal escape from the Liquidity trap

    OpenAIRE

    Mendes, Arthur Galego

    2001-01-01

    I show that when a central bank is financially independent from the treasury and has balance sheet concerns, an increase in the size or a change in the composition of the central bank's balance sheet (quantitative easing) can serve as a commitment device in a liquidity trap scenario. In particular, when the short-term interest rate is up against the zero lower bound, an open market operation by the central bank that involves purchases of long-term bonds can help mitigate the ...

  18. More Fact Sheets - SEER Cancer Statistics

    Science.gov (United States)

    Cancer Statistical Fact Sheets are summaries of common cancer types developed to provide an overview of frequently-requested cancer statistics including incidence, mortality, survival, stage, prevalence, and lifetime risk.

  19. Nanotechnology for Site Remediation: Fact Sheet

    Science.gov (United States)

    This fact sheet presents a snapshot of nanotechnology and its current uses in remediation. It presents information to help site project managers understand the potential applications of this group of technologies at their sites.

  20. Federal Incentives for Wind Power (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2013-05-01

    This fact sheet describes the federal incentives available as of April 2013 that encourage increased development and deployment of wind energy technologies, including research grants, tax incentives, and loan programs.

  1. USFWS Wildlife Health Office Fact Sheet

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This fact sheet provides background information on the Wildlife Health Office, and contains information for reporting sick or dead animals.

  2. More Fact Sheets - SEER Cancer Statistics

    Science.gov (United States)

    Cancer Statistical Fact Sheets are summaries of common cancer types developed to provide an overview of frequently-requested cancer statistics including incidence, mortality, survival, stage, prevalence, and lifetime risk.

  3. Advancing Concentrating Solar Power Research (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2014-02-01

    Researchers at the National Renewable Energy Laboratory (NREL) provide scientific, engineering, and analytical expertise to help advance innovation in concentrating solar power (CSP). This fact sheet summarizes how NREL is advancing CSP research.

  4. Energy Systems Integration: NREL + Solectria (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2015-02-01

    This fact sheet describes the collaboration between NREL and Solectria at the Energy Systems Integration Facility (ESIF) to to develop 500- and 750-kilowatt photovoltaic (PV) inverters with advanced features that can support the electric grid.

  5. Collector/Receiver Characterization (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2010-08-01

    Fact sheet describing NREL CSP Program capabilities for collector/receiver characterization: determining optical efficiency, measuring heat loss, developing and testing concentrators, concentrating the sun's power, and optically characterizing CSP plants.

  6. Sheet Plasma Produced by Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    张龙; 张厚先; 杨宣宗; 冯春华; 乔宾; 王龙

    2003-01-01

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field.The plasma is about 40cm in length,4 cm in width and 1cm in thickness.The electron density is about 108cm-3.The hollow cathode is made to be shallow with a large opening,which is different from the ordinary deep hollow cathode.A Langmuir probe is used to detect the plasma.The electron density and the spatial distribution of the plasma change when voltage,pressure and the magnetic field vary.A peak and a data fluctuation at about 200 G-300 G are observed in the variation of electron density(or thickness of the sheet plasma)with the magnetic field.Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable.

  7. Greenland Radar Ice Sheet Thickness Measurements

    Data.gov (United States)

    National Aeronautics and Space Administration — Two 150-MHz coherent radar depth sounders were developed and flown over the Greenland ice sheet to obtain ice thickness measurements in support of PARCA...

  8. Kevlar reinforced neoprene composites

    Science.gov (United States)

    Penn, B. G.; Daniels, J. G.; White, W. T.; Thompson, L. M.; Clemons, L. M.

    1985-01-01

    Kevlar/neoprene composites were prepared by two techniques. One method involved the fabrication of a composite from a rubber prepreg prepared by coating Kevlar with viscous neoprene solution and then allowing the solvent to evaporate (solution impregnation technique). The second method involved heating a stack of Kevlar/neoprene sheets at a temperature sufficient to cause polymer flow (melt flow technique). There was no significant difference in the breaking strength and percent elongation for samples obtained by the two methods; however the shear strength obtained for samples fabricated by the solution impregnation technique (275 psi) was significantly higher than that found for the melt flow fabricated samples (110 psi).

  9. Thermoforming of thermoplastic composites

    Science.gov (United States)

    McKillop, Brian E.

    Although originally devised for forming unreinfored thermoplastics in sheet form, thermoforming it has been successfully adapted to continuous reinforced thermoplastic composite materials. The conversion rate of this technique is limited only by how fast heat can be added to the thermoplastic matrix to bring it to the processing temperature and the rate at which heat can be removed from the material after the forming process has been completed. Load-to-load cycle times of four minutes have been demonstrated. Processing procedures, equipment, tooling, design consideration and applications are presented to demonstrate that thermoplastic composites can be successfully thermoformed into practical shapes.

  10. Calculation technique for simulation of wave and fracture dynamics in a reinforced sheet

    CERN Document Server

    Ayzenberg-Stepanenko, M; Osharovich, G

    2011-01-01

    Mathematical models and computer algorithms are developed to calculate dynamic stress concentration and fracture wave propagation in a reinforced composite sheet. The composite consists of a regular system alternating extensible fibers and pliable adhesive layers. In computer simulations, we derive difference algorithms preventing or minimizing the parasite distortions caused by the mesh dispersion and obtain precise numerical solutions in the plane fracture problem of a pre-stretched sheet along the fibers. Interactive effects of microscale dynamic deformation and multiple damage in fibers and adhesive are studied. Two engineering models of the composite are considered: the first assumes that adhesive can be represented by inertionless bonds of constant stiffness, while in the second one an adhesive is described by inertial medium perceived shear stresses. Comparison of results allows the evaluation of facilities of models in wave and fracture patterns analysis.

  11. Force focusing in confined fibres and sheets

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Victor; Cerda, Enrique [Departamento de Fisica, Universidad de Santiago, Av. Ecuador 3493, Santiago (Chile); Witten, T A; Liang Tao [James Franck Institute, University of Chicago, Chicago IL 60637 (United States)], E-mail: t-witten@uchicago.edu

    2008-07-07

    A thin fibre or sheet curled into a circular container has a detached region whose shape and force ratios are independent of material properties and container radius. We compute this shape and compare it with experiments. The discrete forces acting at either end of the detached region have a ratio that depends only on the length of the fibre or sheet relative to the circle radius. We calculate this force ratio in three regimes of circle radius. (fast track communication)

  12. Fabrication and Characterization of Nano-CaCO3/Polypropylene Foam Sheets

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    By applying the reinforcing and toughening effect of calcium carbonate (CaCO3) nanoparticles on polypropylene, foam sheets of good performance were successfully fabricated by extrusion. The equipment and conditions of the extrusion were explored. The mechanical properties of the produced foam sheets were tested. The effect of CaCO3 nano-particles on the mechanical properties and the cellular structure of the sheets was comprehensively studied. The experimental results show that the optimum content of CaCO3 nano-particles in the composite material was~4wt%. At this content, the nano-particles were well dispersed in the substrate, and the composite material had maximum tensile strength and impact strength. Surface treatment of the nano-particles only affected the impact strength of the composite material. CaCO3 micro-particles, on the other hand, showed little effect on the properties of the composite material when the micro-particles content was less than 5 wt%. At a content higher than 5wt%, the properties of the composite material significantly worsened.

  13. Fact sheet: Ethanol from corn

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-05-31

    This fact sheet is intended to provide an overview of the advantages of ethanol from corn, emphasizing ethanol`s contribution to environmental protection and sustainable agriculture. Ethanol, an alternative fuel used as an octane enhancer is produced through the conversion of starch to sugars by enzymes, and fermentation of these sugars to ethanol by yeast. The production process may involve wet milling or dry milling. Both these processes produce valuable by-products, in addition to ethanol and carbon dioxide. Ethanol contains about 32,000 BTU per litre. It is commonly believed that using state-of-the-art corn farming and corn processing processes, the amount of energy contained in ethanol and its by-products would be more than twice the energy required to grow and process corn into ethanol. Ethanol represents the third largest market for Ontario corn, after direct use as animal feed and wet milling for starch, corn sweetener and corn oil. The environmental consequences of using ethanol are very significant. It is estimated that a 10 per cent ethanol blend in gasoline would result in a 25 to 30 per cent decrease in carbon monoxide emissions, a 6 to 10 per cent decrease in net carbon dioxide, a slight increase in nitrous oxide emissions which, however, would still result in an overall decrease in ozone formation, since the significant reduction in carbon monoxide emissions would compensate for any slight increase in nitrous oxide. Volatile organic compounds emission would also decrease by about 7 per cent with a 10 per cent ethanol blend. High level blends could reduce VOCs production by as much as 30 per cent. 7 refs.

  14. Radiating Current Sheets in the Solar Chromosphere

    CERN Document Server

    Goodman, Michael L

    2014-01-01

    An MHD model of a Hydrogen plasma with flow, an energy equation, NLTE ionization and radiative cooling, and an Ohm's law with anisotropic electrical conduction and thermoelectric effects is used to self-consistently generate atmospheric layers over a $50$ km height range. A subset of these solutions contain current sheets, and have properties similar to those of the lower and middle chromosphere. The magnetic field profiles are found to be close to Harris sheet profiles, with maximum field strengths $\\sim 25-150$ G. The radiative flux $F_R$ emitted by individual sheets is $\\sim 4.9 \\times 10^5 - 4.5 \\times 10^6$ ergs-cm$^{-2}$-s$^{-1}$, to be compared with the observed chromospheric emission rate of $\\sim 10^7$ ergs-cm$^{-2}$-s$^{-1}$. Essentially all emission is from regions with thicknesses $\\sim 0.5 - 13$ km containing the neutral sheet. About half of $F_R$ comes from sub-regions with thicknesses 10 times smaller. A resolution $\\lesssim 5-130$ m is needed to resolve the properties of the sheets. The sheets...

  15. Buckling Behavior of Substrate Supported Graphene Sheets

    Directory of Open Access Journals (Sweden)

    Kuijian Yang

    2016-01-01

    Full Text Available The buckling of graphene sheets on substrates can significantly degrade their performance in materials and devices. Therefore, a systematic investigation on the buckling behavior of monolayer graphene sheet/substrate systems is carried out in this paper by both molecular mechanics simulations and theoretical analysis. From 70 simulation cases of simple-supported graphene sheets with different sizes under uniaxial compression, two different buckling modes are investigated and revealed to be dominated by the graphene size. Especially, for graphene sheets with length larger than 3 nm and width larger than 1.1 nm, the buckling mode depends only on the length/width ratio. Besides, it is revealed that the existence of graphene substrate can increase the critical buckling stress and strain to 4.39 N/m and 1.58%, respectively, which are about 10 times those for free-standing graphene sheets. Moreover, for graphene sheets with common size (longer than 20 nm, both theoretical and simulation results show that the critical buckling stress and strain are dominated only by the adhesive interactions with substrate and independent of the graphene size. Results in this work provide valuable insight and guidelines for the design and application of graphene-derived materials and nano-electromechanical systems.

  16. Antibubbles and fine cylindrical sheets of air

    KAUST Repository

    Beilharz, D.

    2015-08-14

    Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.

  17. Review of Incremental Forming of Sheet Metal Components

    Directory of Open Access Journals (Sweden)

    Nimbalkar D.H

    2013-09-01

    Full Text Available Incremental sheet forming has demonstrated its great potential to form complex three dimensional parts without using a component specific tooling. The die-less nature in incremental forming provides competitive alternative for economically and effectively fabricating low volume functional sheet products. The process locally deforms sheet metal using a moving tool head achieving higher forming limit than those conventional sheet metal stamping process. Incremental sheet metal forming has the potential to revolutionize sheet metal forming, making it accessible to all level of manufacturing. This paper describes the current state of the art of Incremental sheet metal forming.

  18. On sea level - ice sheet interactions

    Science.gov (United States)

    Gomez, Natalya Alissa

    This thesis focuses on the physics of static sea-level changes following variations in the distribution of grounded ice and the influence of these changes on the stability and dynamics of marine ice sheets. Gravitational, deformational and rotational effects associated with changes in grounded ice mass lead to markedly non-uniform spatial patterns of sea-level change. I outline a revised theory for computing post-glacial sea-level predictions and discuss the dominant physical effects that contribute to the patterns of sea-level change associated with surface loading on different timescales. I show, in particular, that a large sea-level fall (rise) occurs in the vicinity of a retreating (advancing) ice sheet on both short and long timescales. I also present an application of the sea-level theory in which I predict the sea-level changes associated with a new model of North American ice sheet evolution and consider the implications of the results for efforts to establish the sources of Meltwater Pulse 1A. These results demonstrate that viscous deformational effects can influence the amplitude of sea-level changes observed at far-field sea-level sites, even when the time window being considered is relatively short (≤ 500 years). Subsequently, I investigate the feedback of sea-level changes on marine ice-sheet stability and dynamics by coupling a global sea-level model to ice-sheet models of increasing complexity. To begin, I incorporate gravitationally self-consistent sea-level changes into an equilibrium marine ice-sheet stability theory to show that the sea-level changes have a stabilizing influence on ice-sheet retreat. Next, I consider the impact of the stabilizing mechanism on the timescale of ice-sheet retreat using a 1D dynamic coupled ice sheet - sea level model. Simulations with the coupled model, which incorporate viscoelastic deformation of the solid Earth, show that local sea-level changes at the grounding line act to slow, and in some cases, halt

  19. Extended high order sandwich panel theory for bending analysis of sandwich beams with carbon nanotube reinforced face sheets

    Science.gov (United States)

    Jedari Salami, S.

    2016-02-01

    Bending analysis of a sandwich beam with soft core and carbon nanotube reinforced composite (CNTRC) face sheets in the literature is presented based on Extended High order Sandwich Panel Theory (EHSAPT). Distribution of fibers through the thickness of the face sheets could be uniform or functionally graded (FG). In this theory the face sheets follow the first order shear deformation theory (FSDT). Besides, the two dimensional elasticity is used for the core. The field equations are derived via the Ritz based solution which is suitable for any essential boundary condition. The influences of boundary conditions on bending response of the sandwich panel with soft core and CNTRC face sheet are investigated. In each type of boundary condition the effect of distribution pattern of CNTRCs on many essential involved parameters of the sandwich beam with functionally graded carbon nanotube reinforced composite (FG- CNTRC) face sheets are studied in detail. Finally, experimental result have been compared with those obtained based on developed solution method. It is concluded that, the sandwich beam with X distribution figure of face sheets is the strongest with the smallest transverse displacement, and followed by the UD, O and ∧-ones, respectively.

  20. Comparison of manufacturing of lightweight corrugated sheet sandwiches by hydroforming and incremental sheet forming

    Science.gov (United States)

    Maqbool, Fawad; Elze, Lars; Seidlitz, Holger; Bambach, Markus

    2016-10-01

    Sandwich materials made from corrugated sheet metal provide excellent mechanical properties for lightweight design without using filler material. The increased mechanical properties of these sandwich materials are achieved by the 3-D geometry of the corrugated sheet and the hardening due to pre-forming. In the present study, manufacturing of corrugated sheet metal consisting of hexagonal bulge patterns through hydroforming and incremental forming is analyzed. Double layered corrugated sheet metal sandwiches with hexagonal patterns of free-form bulge geometries are investigated through finite element analysis for the maximum increase in stiffness over the normal flat sheets. The analysis shows that a bending stiffness increase of up to 13 times over flat sheet of the same mass is attainable by corrugated sandwiches. Further, it is proved for these types of corrugation sandwiches that stiffness increases by increasing the height of the corrugation bulge but that hydroforming poses restrictions with respect to bulge height, since it is limited by forming force and formability of the material. Incremental sheet metal forming can be used to produce sheets with a hexagonal bulge pattern with increased height. Hence, a higher increase in stiffness as compared to hydroforming is possible but at the expense of process speed.

  1. Best Management Practice, Fact Sheet 2. Sheet Flow to Open Space

    OpenAIRE

    2013-01-01

    This publication explains what sheet flow to open space is, where and how it is used, their limitations, routine and nonroutine maintenance, expected costs, and a glossary of terms. This fact sheet is one of a 15-part series on urban stormwater management practices.

  2. The application of sheet filters in treatment of fruit brandy after cold stabilization

    Directory of Open Access Journals (Sweden)

    Miljić Uroš D.

    2013-01-01

    Full Text Available Considering the common use of sheet filtration for clarification of fruit brandies, the aim of this study was to evaluate the influence of its application on the stability and composition of volatile compounds of apricot brandy after cold stabilisation. Cold stabilisation treatment involved holding of the brandy at -1°C during 24 hours. Five depth filter sheets with the nominal retention rate of 0.3 μm, 0.5-0.7 μm, 0.7-1.0 μm, 1.0-2.0 μm and 2.5-4.0 μm, were tested in the study. It was shown that all assessed filter sheets were efficient in removing chill haze by significantly reducing the content of fatty acid esters (primarily ethyl palmitate and ethyl laurate. Other volatile and aromatic compounds were not significantly influenced by the applied treatments. However, the filter sheets with higher nominal retention rate (> 0.7 μm, had a smaller impact on the sensory characteristics of the apricot brandy. The re-exposure to lower temperatures did not lead to chill haze formation in any sample obtained after sheet filtration. [Projekat Ministarstva nauke Republike Srbije, br. TR-31002

  3. The influence of heat treatment on properties of cold rolled alloyed steel and nickel superalloys sheets used in aircraft industry

    Science.gov (United States)

    Zaba, K.; Dul, I.; Puchlerska, S.

    2017-02-01

    Superalloys based on nickel and selected steels are widely used in the aerospace industry, because of their excellent mechanical properties, heat resistance and creep resistance. Metal sheets of these materials are plastically deformed and applied, inter alia, to critical components of aircraft engines. Due to their chemical composition these materials are hardly deformable. There are various methods to improve the formability of these materials, including plastic deformation at an elevated or high temperature, or a suitable heat treatment before forming process. The paper presents results of the metal sheets testing after heat treatment. For the research, sheets of two types of nickel superalloys type Inconel and of three types of steel were chosen. The materials were subjected to multivariate heat treatment at different temperature range and time. After this step, mechanical properties were examined according to the metal sheet rolling direction. The results were compared and the optimal type of pre-trial softening heat treatment for each of the materials was determined.

  4. Polymer microlenses for quantifying cell sheet mechanics.

    Science.gov (United States)

    Miquelard-Garnier, Guillaume; Zimberlin, Jessica A; Sikora, Christian B; Wadsworth, Patricia; Crosby, Alfred

    2010-01-01

    Mechanical interactions between individual cells and their substrate have been studied extensively over the past decade; however, understanding how these interactions change as cells interact with neighboring cells in the development of a cell sheet, or early stage tissue, is less developed. We use a recently developed experimental technique for quantifying the mechanics of confluent cell sheets. Living cells are cultured on a thin film of polystyrene [PS], which is attached to a patterned substrate of crosslinked poly(dimethyl siloxane) [PDMS] microwells. As cells attach to the substrate and begin to form a sheet, they apply sufficient contractile force to buckle the PS film over individual microwells to form a microlens array. The curvature for each microlens is measured by confocal microscopy and can be related to the strain and stress applied by the cell sheet using simple mechanical analysis for the buckling of thin films. We demonstrate that this technique can provide insight into the important materials properties and length scales that govern cell sheet responses, especially the role of stiffness of the substrate. We show that intercellular forces can lead to significantly different behaviors than the ones observed for individual cells, where focal adhesion is the relevant parameter.

  5. Carbonized Electrospun Nanofiber Sheets for Thermophones.

    Science.gov (United States)

    Aliev, Ali E; Perananthan, Sahila; Ferraris, John P

    2016-11-16

    Thermoacoustic performance of thin freestanding sheets of carbonized poly(acrylonitrile) and polybenzimidazole nanofibers are studied as promising candidates for thermophones. We analyze thermodynamic properties of sheets using transport parameters of single nanofibers and their aligned and randomly electrospun thin film assemblies. The electrical and thermal conductivities, thermal diffusivity, heat capacity, and infrared blackbody radiation are investigated to extract the heat exchange coefficient and enhance the energy conversion efficiency. Spectral and power dependencies of sound pressure in air are compared with carbon nanotube sheets and theoretical prediction. Despite lower thermoacoustic performance compared to that of CNT sheets, the mechanical strength and cost-effective production technology of thermophones make them very attractive for large-size sound projectors. The advantages of carbonized electrospun polymer nanofiber sheets are in the low frequency domain (<1000 Hz), where the large thermal diffusion length diminishes the thermal inertia of thick (∼200 nm) nonbundled fibers and the high intrinsic thermal conductivity of fibers enhances the heat exchange coefficient. Applications of thermoacoustic projectors for loudspeakers, high power SONAR arrays, and sound cancellation are discussed.

  6. Clouds enhance Greenland ice sheet meltwater runoff

    Science.gov (United States)

    Van Tricht, Kristof; Lhermitte, Stef; Lenaerts, Jan T. M.; Gorodetskaya, Irina V.; L'Ecuyer, Tristan S.; Noël, Brice; van den Broeke, Michiel R.; Turner, David D.; van Lipzig, Nicole P. M.

    2016-04-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m-2. Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise.

  7. Fluctuation dynamics in reconnecting current sheets

    Science.gov (United States)

    von Stechow, Adrian; Grulke, Olaf; Ji, Hantao; Yamada, Masaaki; Klinger, Thomas

    2015-11-01

    During magnetic reconnection, a highly localized current sheet forms at the boundary between opposed magnetic fields. Its steep perpendicular gradients and fast parallel drifts can give rise to a range of instabilities which can contribute to the overall reconnection dynamics. In two complementary laboratory reconnection experiments, MRX (PPPL, Princeton) and VINETA.II (IPP, Greifswald, Germany), magnetic fluctuations are observed within the current sheet. Despite the large differences in geometries (toroidal vs. linear), plasma parameters (high vs. low beta) and magnetic configuration (low vs. high magnetic guide field), similar broadband fluctuation characteristics are observed in both experiments. These are identified as Whistler-like fluctuations in the lower hybrid frequency range that propagate along the current sheet in the electron drift direction. They are intrinsic to the localized current sheet and largely independent of the slower reconnection dynamics. This contribution characterizes these magnetic fluctuations within the wide parameter range accessible by both experiments. Specifically, the fluctuation spectra and wave dispersion are characterized with respect to the magnetic topology and plasma parameters of the reconnecting current sheet.

  8. Ice Sheet Thermomety Using Wideband Radiometry

    Science.gov (United States)

    Jezek, K. C.; Johnson, J.; Durand, M. T.; Aksoy, M.; Tsang, L.; Wang, T.; Tan, S.; Macelloni, G.; Brogioni, M.; Drinkwater, M. R.

    2014-12-01

    There are good correlations between L-band brightness temperature data from the ESA Soil Moisture and Ocean Salinity mission and the thickness and surface temperature of the Antarctic Ice Sheet. These data along with independent, radiative-transfer modeling-studies suggest that it is possible to estimate the internal, physical temperatures of ice sheets to some, perhaps great, depth. Such a measurement is necessary to improve ice sheet models which rely on temperature-dependent deformation rates within the body of the ice sheet. In this paper we review our most recent modeling which now includes the effect of layering in near surface firn. We go on to compare L-band satellite data with modeled brightness temperatures at several sites in Greenland and Antarctica where physical temperature has been measured. We show the brightness temperature response over the band 0.5 to 2 GHz including the influence of basal-water on the low frequency range of this band. We conclude by summarizing our current design of an ultra-wide-band radiometer intended to make ice sheet thermometry measurements. We plan to deploy the airborne instrument in Greenland in two years' time.

  9. Clouds enhance Greenland ice sheet meltwater runoff.

    Science.gov (United States)

    Van Tricht, K; Lhermitte, S; Lenaerts, J T M; Gorodetskaya, I V; L'Ecuyer, T S; Noël, B; van den Broeke, M R; Turner, D D; van Lipzig, N P M

    2016-01-12

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m(-2). Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise.

  10. Clouds enhance Greenland ice sheet meltwater runoff

    Science.gov (United States)

    Van Tricht, K.; Lhermitte, S.; Lenaerts, J. T. M.; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B.; van den Broeke, M. R.; Turner, D. D.; van Lipzig, N. P. M.

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m−2. Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise. PMID:26756470

  11. Thermally induced changes in the focal distance of composite mirrors - Composites with a zero coefficient of thermal expansion of the radius of curvature

    Science.gov (United States)

    Dolgin, Benjamin P.

    1992-01-01

    Calculations are presented of the coefficient of thermal expansion (CTE) of the radius of curvature of the reflector face sheets made of a quasi-isotropic composite. It is shown that, upon cooling, the change of the CTE of the focal distance of the mirror is equal to that of the radius of the curvature of the reflector face sheet. The CTE of the radius of the curvature of a quasi-isotropic composite face sheet depends on both the in-plane and the out-of-plane CTEs. The zero in-plane CTE of a face sheet does not guarantee mirrors with no focal length changes.

  12. Supraglacial bacterial community structures vary across the Greenland ice sheet.

    Science.gov (United States)

    Cameron, Karen A; Stibal, Marek; Zarsky, Jakub D; Gözdereliler, Erkin; Schostag, Morten; Jacobsen, Carsten S

    2016-02-01

    The composition and spatial variability of microbial communities that reside within the extensive (>200 000 km(2)) biologically active area encompassing the Greenland ice sheet (GrIS) is hypothesized to be variable. We examined bacterial communities from cryoconite debris and surface ice across the GrIS, using sequence analysis and quantitative PCR of 16S rRNA genes from co-extracted DNA and RNA. Communities were found to differ across the ice sheet, with 82.8% of the total calculated variation attributed to spatial distribution on a scale of tens of kilometers separation. Amplicons related to Sphingobacteriaceae, Pseudanabaenaceae and WPS-2 accounted for the greatest portion of calculated dissimilarities. The bacterial communities of ice and cryoconite were moderately similar (global R = 0.360, P = 0.002) and the sampled surface type (ice versus cryoconite) did not contribute heavily towards community dissimilarities (2.3% of total variability calculated). The majority of dissimilarities found between cryoconite 16S rRNA gene amplicons from DNA and RNA was calculated to be the result of changes in three taxa, Pseudanabaenaceae, Sphingobacteriaceae and WPS-2, which together contributed towards 80.8 ± 12.6% of dissimilarities between samples. Bacterial communities across the GrIS are spatially variable active communities that are likely influenced by localized biological inputs and physicochemical conditions.

  13. Quantitative Evaluation for Drawability of Sheet Metal

    Institute of Scientific and Technical Information of China (English)

    Zhiqing XIONG; Xuemei YANG

    2005-01-01

    The theoretical evaluating method is given for the drawability of the sheet with normal anisotropy. The general solution on the cracking load of deep-drawing is deduced, which is based on three kinds of hardening curve of materials most in use. The distributions of stress and strain in the deformed region and the drawing force are obtained by the numerical method. The limiting drawing ratio is calculated through computer-aided simulating test. The experiments of deep-drawing to four kinds of sheet metals express that the relative errors between the predictive and the experimental results about the cracking load and the limiting drawing ratio are within 5%. The drawability of common sheet metals can be quantitatively evaluated in precise terms by means of the theory and the method advanced in this paper.

  14. Dynamic of particle-laden liquid sheet

    Science.gov (United States)

    Sauret, Alban; Jop, Pierre; Troger, Anthony

    2016-11-01

    Many industrial processes, such as surface coating or liquid transport in tubes, involve liquid sheets or thin liquid films of suspensions. In these situations, the thickness of the liquid film becomes comparable to the particle size, which leads to unexpected dynamics. In addition, the classical constitutive rheological law cannot be applied as the continuum approximation is no longer valid. Here, we consider experimentally a transient free liquid sheet that expands radially. We characterize the influence of the particles on the shape of the liquid film as a function of time and the atomization process. We highlight that the presence of particles modifies the thickness and the stability of the liquid sheet. Our study suggests that the influence of particles through capillary effects can modify significantly the dynamics of processes that involve suspensions and particles confined in liquid films.

  15. Two-mirrored galvanometer laser light sheet generator

    Science.gov (United States)

    Leighty, B. D.; Franke, J. M.; Jones, S. B.; Rhodes, D. B.

    1988-01-01

    Light sheets generated with either laser or noncoherent sources have found widespread application to flow visualization. Previous light sheet generating systems were usually dedicated to a specific viewing geometry. The technique with the most flexibility is the galvanometer mirror based laser light sheet system. A two-mirrored system was designed and developed to provide flexibility and adaptability to a wide range of applications. The design includes the capability to control the size and location of the laser light sheet in real time, to generate horizontal or vertical sheets, to sweep the sheet repeatedly through a volume, to generate multiple sheets with controllable separation and to rotate single or multiple laser light sheets. The system is capable of producing up to 12 sheets of laser light at an angular divergence of + or - 20 degrees. Maximum scan rate of any one line is 500 Hertz. This system has proven to be uniquely versatile and a patent has been applied for.

  16. Light-sheet optimization for microscopy

    Science.gov (United States)

    Wilding, Dean; Pozzi, Paolo; Soloviev, Oleg; Vdovin, Gleb; Verhaegen, Michel

    2016-03-01

    Aberrations, scattering and absorption degrade the performance light-sheet fluorescence microscopes (LSFM). An adaptive optics system to correct for these artefacts and to optimize the light-sheet illumination is presented. This system allows a higher axial resolution to be recovered over the field-of-view of the detection objective. It is standard selective plane illumination microscope (SPIM) configuration modified with the addition of a spatial light modulator (SLM) and a third objective for the detection of transmitted light. Optimization protocols use this transmission light allowing the extension the depth-of-field and correction of aberrations whilst retaining a thin optical section.

  17. Interfacial Assembly of Graphene Oxide Sheets

    Science.gov (United States)

    Cote, Laura J.

    Scientific interest in graphene oxide (GO) sheets, the product of chemical oxidation and exfoliation of graphite powder, has resurged in recent years because GO is considered a promising precursor for the bulk production of graphene-based sheets for a variety of applications. In addition, GO can be viewed as an unconventional type of soft material as it is characterized by two abruptly different length scales. Its thickness is of typical molecular dimensions, measured to be about 1 nm by atomic force microscopy, but its lateral dimensions are that of common colloidal particles, ranging from nanometers to tens of microns. This high anisotropy leads to interesting fundamental colloidal interactions between the soft sheets which have practical implications in the solution processing and assembly of the material. This research therefore aims to use a variety of techniques to control these inter-sheet interactions to gain an understanding of the processing-structure relationships which ultimately determine the overall properties of the bulk GO assembly. GO is identified as a two-dimensional amphiphile with a unique edge-to-center arrangement of hydrophilic and hydrophobic groups, which has led to the demonstration of its pH- and size-dependent surface activity. The water surface is then utilized, as in the Langmuir-Blodgett technique, as an ideal substrate to tile up the GO sheets and study the interactions between them. Sheet-sheet interaction morphologies were successfully altered between wrinkled and overlapped states by pH tuning of sheet charge density, and the resulting structure-property relationships are explored. In addition, a novel flash-reduction and assembly process is described in which a simple photographic camera flash can rapidly and cleanly turn an insulating, well-stacked GO paper to a more open and fluffy conducting film. Lastly, the use of these research results as educational outreach platforms is highlighted. A variety of outlets, such as You

  18. Strategic financial planning: a balance sheet perspective.

    Science.gov (United States)

    Cleverley, W O

    1987-02-01

    This paper presents an easily comprehended approach to the strategic financial planning process. It utilizes a balance sheet approach that focuses attention on three key business policy decisions: asset growth rates, debt policy, and equity growth policy. Because the approach taken here does not get involved with the numerous assumptions and projections involved in a typical funds flow approach to financial planning, it is easier to understand and use by both boards and top management. A financial plan is defined as a bridge between two balance sheets.

  19. Clouds enhance Greenland ice sheet meltwater runoff

    OpenAIRE

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2)Wm-2. Co...

  20. Data analysis & probability task & drill sheets

    CERN Document Server

    Cook, Tanya

    2011-01-01

    For grades 3-5, our State Standards-based combined resource meets the data analysis & probability concepts addressed by the NCTM standards and encourages your students to review the concepts in unique ways. The task sheets introduce the mathematical concepts to the students around a central problem taken from real-life experiences, while the drill sheets provide warm-up and timed practice questions for the students to strengthen their procedural proficiency skills. Included in our resource are activities to help students learn how to collect, organize, analyze, interpret, and predict data pro

  1. Nonlinear spacial instability of a fluid sheet

    Science.gov (United States)

    Rangel, R. H.; Hess, C. F.

    1990-01-01

    The mechanism of nonlinear distortion of a fluid sheet leading to atomization is investigated numerically with the use of vortex dynamics and experimentally by means of holography. The configuration investigated consists of a planar fluid sheet emerging from a rectangular slit with and without coflowing air. The numerical model is two-dimensional, inviscid, and includes surface tension effects. The experimental results indicate the existence of well-defined three-dimensional structures. These are formed mainly by the nonlinear interaction of transverse and streamwise disturbances. The transverse disturbances are associated with the Kelvin-Helmholtz instability while the streamwise disturbances appear related to streamwise vortices possibly originating inside the nozzle.

  2. Physics of the magnetotail current sheet

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J. (Beam Physics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States))

    1993-07-01

    The Earth's magnetotail plays an important role in the solar-wind--magnetosphere coupling. At the midplane of the magnetotail is a current sheet where the dominant magnetic field component reverses sign. The charged particle motion in and near the current sheet is collisionless and nonintegrable, exhibiting chaotic scattering. The current understanding of the dynamical properties of the charged particle motion is discussed. In particular, the relationships between particle dynamics and global attributes of the system are elucidated. Geometrical properties of the phase space determine important physical observables on both micro- and macroscales.

  3. FORMABILITY OF THIN SHEETS FROM ALUMINUM ALLOYS

    Directory of Open Access Journals (Sweden)

    Emil Spišák

    2016-12-01

    Full Text Available In this contribution there have been evaluated properties of four types of sheets made from aluminium alloys. In the case of each of the examined sheets there has been checked its shearing ability via the influence of punch-die clearance change on the quality of blanking edge. Quality of blanking edge is characterized by a ratio of plastic zone height to the total thickness of the sheared material. Formability during the drawing process was measured with earring test. Results are presented by the earring coefficient (unequal height of the cups.

  4. Clouds enhance Greenland ice sheet meltwater runoff

    OpenAIRE

    K. Van Tricht; Lhermitte, S.; Lenaerts, J. T. M.; Gorodetskaya, I. V.; L'Ecuyer, T. S.; Noël, B; Van Den Broeke, M.R.; Turner, D. D.; Van Lipzig, N. P. M.

    2016-01-01

    The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2)Wm-2. Co...

  5. Twin-Mirrored-Galvanometer Laser-Light-Sheet Generator

    Science.gov (United States)

    Rhodes, David B.; Franke, John M.; Jones, Stephen B.; Leighty, Bradley D.

    1991-01-01

    Multiple, rotating laser-light sheets generated to illuminate flows in wind tunnels. Designed and developed to provide flexibility and adaptability to wide range of applications. Design includes capability to control size and location of laser-light sheet in real time, to generate horizontal or vertical sheets, to sweep sheet repeatedly through volume, to generate multiple sheets with controllable separation, and to rotate single or multiple laser-light sheets. Includes electronic equipment and laser mounted on adjustable-height platform. Twin-mirrored galvanometer unit supported by tripod to reduce vibration. Other possible applications include use in construction industry to align beams of building. Artistic or display applications also possible.

  6. Laminin-521 Promotes Rat Bone Marrow Mesenchymal Stem Cell Sheet Formation on Light-Induced Cell Sheet Technology

    Directory of Open Access Journals (Sweden)

    Zhiwei Jiang

    2017-01-01

    Full Text Available Rat bone marrow mesenchymal stem cell sheets (rBMSC sheets are attractive for cell-based tissue engineering. However, methods of culturing rBMSC sheets are critically limited. In order to obtain intact rBMSC sheets, a light-induced cell sheet method was used in this study. TiO2 nanodot films were coated with (TL or without (TN laminin-521. We investigated the effects of laminin-521 on rBMSCs during cell sheet culturing. The fabricated rBMSC sheets were subsequently assessed to study cell sheet viability, reattachment ability, cell sheet thickness, collagen type I deposition, and multilineage potential. The results showed that laminin-521 could promote the formation of rBMSC sheets with good viability under hyperconfluent conditions. Cell sheet thickness increased from an initial 26.7 ± 1.5 μm (day 5 up to 47.7 ± 3.0 μm (day 10. Moreover, rBMSC sheets maintained their potential of osteogenic, adipogenic, and chondrogenic differentiation. This study provides a new strategy to obtain rBMSC sheets using light-induced cell sheet technology.

  7. Characterization of Hybrid CNT Polymer Matrix Composites

    Science.gov (United States)

    Grimsley, Brian W.; Cano, Roberto J.; Kinney, Megan C.; Pressley, James; Sauti, Godfrey; Czabaj, Michael W.; Kim, Jae-Woo; Siochi, Emilie J.

    2015-01-01

    Carbon nanotubes (CNTs) have been studied extensively since their discovery and demonstrated at the nanoscale superior mechanical, electrical and thermal properties in comparison to micro and macro scale properties of conventional engineering materials. This combination of properties suggests their potential to enhance multi-functionality of composites in regions of primary structures on aerospace vehicles where lightweight materials with improved thermal and electrical conductivity are desirable. In this study, hybrid multifunctional polymer matrix composites were fabricated by interleaving layers of CNT sheets into Hexcel® IM7/8552 prepreg, a well-characterized toughened epoxy carbon fiber reinforced polymer (CFRP) composite. The resin content of these interleaved CNT sheets, as well as ply stacking location were varied to determine the effects on the electrical, thermal, and mechanical performance of the composites. The direct-current electrical conductivity of the hybrid CNT composites was characterized by in-line and Montgomery four-probe methods. For [0](sub 20) laminates containing a single layer of CNT sheet between each ply of IM7/8552, in-plane electrical conductivity of the hybrid laminate increased significantly, while in-plane thermal conductivity increased only slightly in comparison to the control IM7/8552 laminates. Photo-microscopy and short beam shear (SBS) strength tests were used to characterize the consolidation quality of the fabricated laminates. Hybrid panels fabricated without any pretreatment of the CNT sheets resulted in a SBS strength reduction of 70 percent. Aligning the tubes and pre-infusing the CNT sheets with resin significantly improved the SBS strength of the hybrid composite To determine the cause of this performance reduction, Mode I and Mode II fracture toughness of the CNT sheet to CFRP interface was characterized by double cantilever beam (DCB) and end notch flexure (ENF) testing, respectively. Results are compared to the

  8. Highly efficient visible light mediated azo dye degradation through barium titanate decorated reduced graphene oxide sheets

    Science.gov (United States)

    Rastogi, Monisha; Kushwaha, H. S.; Vaish, Rahul

    2016-03-01

    This study investigates BaTiO3 decorated reduced graphene oxide sheets as a potential visible light active catalyst for dye degradation (Rhodamine B). The composites were prepared through conventional hydrothermal synthesis technique using hydrazine as a reducing agent. A number of techniques have been employed to affirm the morphology, composition and photocatalytic properties of the composites; these include UV-visible spectrophotoscopy that assisted in quantifying the concentration difference of Rhodamine B. The phase homogeneity of the composites was examined through x-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) was employed to confirm the orientation of the BaTiO3 particles over the reduced graphene oxide sheets. Photoluminescence (PL) emission spectra assisted in determining the surface structure and excited state of the catalyst. Fourier transformed-infrared (FTIR) spectra investigated the vibrations and adsorption peak of the composites, thereby ascertaining the formation of reduced graphene oxide. In addition, diffuse reflectance spectroscopy (DRS) demonstrated an enhanced absorption in the visible region. The experimental investigations revealed that graphene oxide acted as charge collector and simultaneously facilitated surface adsorption and photo-sensitization. It could be deduced that BaTiO3-reduced graphene oxide composites are of significant interest the field of water purification through solar photocatalysis. [Figure not available: see fulltext.

  9. Effect of drawbead on forming performance of subsequent sheet

    Institute of Scientific and Technical Information of China (English)

    李群; 郭宝峰; 金淼; 孙成丽

    2008-01-01

    In order to research the plastic performance of sheet going through the drawbead and the simple tensile test of sheet, the influence of drawbead structure parameters on sheet performance and the subsequent performance of the sheet were performed to investigate the residual deformation characteristics of the sheet through different drawbead structures, and also the influences of drawbead structures and geometry parameters on pre-deformation and subsequent forming characters of sheet were analyzed. The results show that the pre-deformation decreases with the increase of the round corner radius, the pre-deformation increase with the increase of the height of drawbead, and the subsequent forming characteristics of sheet going through drawbead are remarkably different from undeformed sheet and these differences heavily depend on the pre-deformation. With the increases of pre-deformation, the yield ratio increases, but the subsequent elongation exponential decreases. These means deformability of the sheet is significantly reduced. As the structure of drawbead changes, the mechanical characteristics of material in different cyclic loading conditions also change. For the BUFDE+Z deep drawing steel sheet, the subsequent performance of the sheet is hardened when the pre-deformation is greater than 0.044. For the DC52D+ZF hot-galvanize steel sheet, the subsequent performance of the sheet begins to harden when the pre-deformation is greater than 0.079, and it presents that the pre-deformation is not bigger than 0.052.

  10. Number & operations drill sheets : grades PK-2

    CERN Document Server

    Reed, Nat

    2010-01-01

    For grades PK-2, our Common Core State Standards-based resource meets the number & operations concepts addressed by the NCTM standards and encourages the students to review the concepts in unique ways. Each drill sheet contains warm-up and timed drill activities for the student to practice number & operations concepts.

  11. Full size testing of sheet pile walls

    NARCIS (Netherlands)

    Kuilen, J.W.G. van de; Linden, M.L.R. van der; Katsma, H.; Stolle, P.

    1996-01-01

    Azobé (Lophira alata) is widely used in timber sheet pile walls in the Netherlands. The boards in these walls are coupled and therefore load-sharing can be expected. A simulation model based on the finite element method DIANA (DIANA, 1992) was developed and load-sharing could be calculated. To check

  12. Fact Sheet on Vouchers. Argument and Evidence.

    Science.gov (United States)

    American Educator, 1995

    1995-01-01

    Much controversy surrounds the idea of vouchers parents could apply to private education. Information about existing private school admission policies, student characteristics, student achievement, market competition, and costs is summarized in this fact sheet. The superiority claimed for private school education can be explained by student…

  13. Algebra task sheets : grades pk-2

    CERN Document Server

    Reed, Nat

    2009-01-01

    For grades PK-2, our Common Core State Standards-based resource meets the algebraic concepts addressed by the NCTM standards and encourages the students to learn and review the concepts in unique ways. Each task sheet is organized around a central problem taken from real-life experiences of the students.

  14. Geometry task sheets : grades pk-2

    CERN Document Server

    Rosenberg, Mary

    2009-01-01

    For grades PK-2, our Common Core State Standards-based resource meets the geometry concepts addressed by the NCTM standards and encourages the students to learn and review the concepts in unique ways. Each task sheet is organized around a central problem taken from real-life experiences of the students.

  15. Algebra task sheets : grades 3-5

    CERN Document Server

    Reed, Nat

    2009-01-01

    For grades 3-5, our Common Core State Standards-based resource meets the algebraic concepts addressed by the NCTM standards and encourages the students to learn and review the concepts in unique ways. Each task sheet is organized around a central problem taken from real-life experiences of the students.

  16. Geometry task sheets : grades 3-5

    CERN Document Server

    Rosenberg, Mary

    2009-01-01

    For grades 3-5, our Common Core State Standards-based resource meets the geometry concepts addressed by the NCTM standards and encourages the students to learn and review the concepts in unique ways. Each task sheet is organized around a central problem taken from real-life experiences of the students.

  17. Volunteering among Young People. Fact Sheet

    Science.gov (United States)

    Lopez, Mark Hugo; Marcelo, Karlo Barrios

    2007-01-01

    This fact sheet presents information on the frequency of volunteering, trends in volunteering, and the organizations for which young people volunteer, utilizing data from multiple sources. Unlike many surveys, it shows that volunteering rates among young people are generally higher than they are among adults 26 and older. Findings of the Civic and…

  18. Volunteering among High School Students. Fact Sheet

    Science.gov (United States)

    Marcelo, Karlo Barrios

    2007-01-01

    This fact sheet explores volunteering among high school students, ages 16-18. Overall, volunteering among high school students was down slightly in 2006 as compared to 2005. Additional information includes types of volunteer organizations and activities, and ways that high school students become involved in these activities. Volunteer rate vary by…

  19. beta-sheet preferences from first principles

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Bækgaard, Iben Sig Buur; Gregersen, Misha Marie

    2003-01-01

    The natural amino acids have different preferences of occurring in specific types of secondary protein structure. Simulations are performed on periodic model â-sheets of 14 different amino acids, at the level of density functional theory, employing the generalized gradient approximation. We find ...

  20. Lubricant Test Methods for Sheet Metal Forming

    DEFF Research Database (Denmark)

    Bay, Niels; Olsson, David Dam; Andreasen, Jan Lasson

    2008-01-01

    Sheet metal forming of tribologically difficult materials such as stainless steel, Al-alloys and Ti-alloys or forming in tribologically difficult operations like ironing, punching or deep drawing of thick plate requires often use of environmentally hazardous lubricants such as chlorinated paraffin...

  1. Energy Systems Integration: NREL + Google (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2015-02-01

    This fact sheet describes the collaboration between NREL, Google, and the IEEE Power Electronics Society at the ESIF to work on the Little Box Challenge, an open competition challenging engineers to build smaller power inverters for use in photovoltaic power systems.

  2. Renewable Energy Project Development Assistance (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2013-07-01

    This fact sheet provides information on the Tribes selected to receive assistance from the U.S. Department of Energy Office of Indian Energy 2013 Strategic Technical Assistance Response Team (START) Program, which provides technical expertise to support the development of next-generation energy projects on tribal lands.

  3. New strings with world-sheet supersymmetry

    CERN Document Server

    Nichols, A; Savvidy, G K

    2004-01-01

    We suggest a new model of string theory with world-sheet supersymmetry. It possesses an additional global fermionic symmetry which is similar in many ways to BRST symmetry. The spectrum consists of massless states of Rarita-Schwinger fields describing infinite tower of half-integer spins.

  4. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet

    Science.gov (United States)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.

    1993-01-01

    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  5. Alternative Fuels Data Center (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2013-07-01

    Fact sheet describes the Alternative Fuels Data Center, which provides information, data, and tools to help fleets and other transportation decision makers find ways to reduce petroleum consumption through the use of alternative and renewable fuels, advanced vehicles, and other fuel-saving measures.

  6. State Civic Education Requirements. CIRCLE Fact Sheet

    Science.gov (United States)

    Godsay, Surbhi; Henderson, Whitney; Levine, Peter; Littenberg-Tobias, Josh

    2012-01-01

    This fact sheet summarizes state requirements related to civic education, which means learning about citizenship, government, law, current events, and related topics. Civic education is most directly addressed in courses labeled "civics," "government," or "U.S. government." Social studies is a broader category that…

  7. Multiscale friction modeling for sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; de Rooij, Matthias B.; Meinders, Vincent T.; Felder, Eric; Montmitonnet, Pierre

    2010-01-01

    The most often used friction model for sheet metal forming simulations is the relative simple Coulomb friction model. This paper presents a more advanced friction model for large scale forming simulations based on the surface change on the micro-scale. The surface texture of a material changes when

  8. Pelvic Inflammatory Disease (PID) Fact Sheet

    Science.gov (United States)

    ... Search Form Controls Cancel Submit Search the CDC Pelvic Inflammatory Disease (PID) Note: Javascript is disabled or is not ... Twitter STD on Facebook Sexually Transmitted Diseases (STDs) Pelvic Inflammatory Disease (PID) - CDC Fact Sheet Language: English (US) Españ ...

  9. Solar Technical Assistance Team (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2012-07-01

    The Solar Technical Assistance Team (STAT) is a team of solar technology and deployment experts who ensure that the best information on policies, regulations, financing, and other issues is getting into the hands of state government decision makers whey they need it. This fact sheet provides information about STAT and the STAT webinar series for the summer of 2012.

  10. "Turtle Island Tales." Cue Sheet for Students.

    Science.gov (United States)

    Carr, Gail

    This performance guide is designed for teachers to use with students before and after a shadow play performance of "Turtle Island Tales" by Hobey Ford and His Golden Rod Puppets. The guide, called a "Cuesheet," contains seven activity sheets for use in class, addressing: (1) The Tales (offering brief outlines of the three tales…

  11. Ice sheets on plastically-yielding beds

    Science.gov (United States)

    Hewitt, Ian

    2016-11-01

    Many fast flowing regions of ice sheets are underlain by a layer of water-saturated sediments, or till. The rheology of the till has been the subject of some controversy, with laboratory tests suggesting almost perfectly plastic behaviour (stress independent of strain rate), but many models adopting a pseudo-viscous description. In this work, we consider the behaviour of glaciers underlain by a plastic bed. The ice is treated as a viscous gravity current, on a bed that allows unconstrained slip above a critical yield stress. This simplified description allows rapid sliding, and aims to investigate 'worst-case' scenarios of possible ice-sheet disintegration. The plastic bed results in an approximate ice-sheet geometry that is primarily controlled by force balance, whilst ice velocity is determined from mass conservation (rather than the other way around, as standard models would hold). The stability of various states is considered, and particular attention is given to the pace at which transitions between unstable states can occur. Finally, we observe that the strength of basal tills depends strongly on pore pressure, and combine the model with a description of subglacial hydrology. Implications for the present-day ice sheets in Greenland and Antarctica will be discussed. Funding: ERC Marie Curie FP7 Career Integration Grant.

  12. Sheet Membrane Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  13. Monitoring ice sheet behavior from space

    Science.gov (United States)

    Bindschadler, Robert

    1998-02-01

    Satellite remote sensing has revolutionized ice sheet research. A variety of instruments sensitive to different parts of the electromagnetic spectrum take what the human eye detects as a flat, white desert and provide data sets rich in scientific information. Image-based maps of ice sheets are becoming commonplace and have become an integral component of field work. More than a pretty picture, the digital character of the satellite data from these instruments has become fundamental to the production of elevation, motion, accumulation, and reflectance data sets. Visible imagery shows the scientist a wealth of features that offer clues to the history and current behavior of the ice sheet. Radar and microwave imagery provide information from beneath the surface and have been used to estimate snow accumulation rates. Interferometry principles have recently been applied to measure surface topography and ice motion with unparalleled precision. Nonimaging instruments also keep a watchful eye, monitoring the ice sheet for indications of growth or shrinkage. Further expansion of the uses of satellite data is anticipated in the future.

  14. Advanced Technological Education Survey 2010 Fact Sheet

    Science.gov (United States)

    Wingate, Lori; Westine, Carl; Gullickson, Arlen

    2010-01-01

    This fact sheet summarizes data gathered in the 2010 survey of National Science Foundation (NSF) Advanced Technological Education (ATE) grant recipients. Conducted by EvaluATE, the evaluation resource center for the ATE program located at The Evaluation Center at Western Michigan University, this was the eleventh annual survey of ATE projects and…

  15. Advanced Technological Education Survey 2012 Fact Sheet

    Science.gov (United States)

    Wingate, Lori; Smith, Corey; Westine, Carl; Gullickson, Arlen

    2012-01-01

    This fact sheet summarizes data gathered in the 2012 survey of National Science Foundation (NSF) Advanced Technological Education (ATE) grant recipients. Conducted by EvaluATE, the evaluation resource center for the ATE program located at The Evaluation Center at Western Michigan University, this was the thirteenth annual survey of ATE projects…

  16. Advanced Technological Education Survey 2011 Fact Sheet

    Science.gov (United States)

    Wingate, Lori; Westine, Carl; Gullickson, Arlen

    2011-01-01

    This fact sheet summarizes data gathered in the 2011 survey of National Science Foundation (NSF) Advanced Technological Education (ATE) grant recipients. Conducted by EvaluATE, the evaluation resource center for the ATE program located at The Evaluation Center at Western Michigan University, this was the twelfth annual survey of ATE projects and…

  17. Glacial Cycles and ice-sheet modelling

    NARCIS (Netherlands)

    Oerlemans, J.

    1982-01-01

    An attempt is made to simulate the Pleistocene glacial cycles with a numerical model of the Northern Hemisphere ice sheets. This model treats the vertically-integrated ice flow along a meridian, including computation of bedrock adjustment and temperature distribution in the ice. Basal melt water is

  18. A model of the Antarctic Ice Sheet

    NARCIS (Netherlands)

    Oerlemans, J.

    1982-01-01

    Numerical modelling of ice sheets and glaciers has become a useful tool in glaciological research. A model described here deals with the vertical mean ice velocity, is time dependent, computes bedrock adjustment and uses an empirical diagnostic relationship to derive the distribution of ice thicknes

  19. Guided bone regeneration using individualized ceramic sheets.

    Science.gov (United States)

    Malmström, J; Anderud, J; Abrahamsson, P; Wälivaara, D-Å; Isaksson, S G; Adolfsson, E

    2016-10-01

    Guided bone regeneration (GBR) describes the use of membranes to regenerate bony defects. A membrane for GBR needs to be biocompatible, cell-occlusive, non-toxic, and mouldable, and possess space-maintaining properties including stability. The purpose of this pilot study was to describe a new method of GBR using individualized ceramic sheets to perfect bone regeneration prior to implant placement; bone regeneration was assessed using traditional histology and three-dimensional (3D) volumetric changes in the bone and soft tissue. Three patients were included. After full-thickness flap reflection, the individualized ceramic sheets were fixed. The sites were left to heal for 7 months. All patients were evaluated preoperatively and at 7 months postoperative using cone beam computed tomography and 3D optical equipment. Samples of the regenerated bone and soft tissue were collected and analyzed. The bone regenerated in the entire interior volume of all sheets. Bone biopsies revealed newly formed trabecular bone with a lamellar structure. Soft tissue biopsies showed connective tissue with no signs of an inflammatory response. This was considered to be newly formed periosteum. Thus ceramic individualized sheets can be used to regenerate large volumes of bone in both vertical and horizontal directions independent of the bone defect and with good biological acceptance of the material.

  20. Understanding Greenland Ice Sheet Runoff Losses

    Science.gov (United States)

    Rennermalm, A. K.; Tedesco, M.; Smith, L. C.; Pitcher, L. H.; Mote, T. L.; Yager, P. L.; Moustafa, S.; Cooper, M. G.; van As, D.; Hasholt, B.; Mikkelsen, A. B.

    2016-12-01

    One of the main ways the ice sheet loses mass is by meltwater runoff. Because of Greenland's great size, regional surface mass balance models are key to understanding large-scale runoff patterns and trends. At the same time, remote sensing and field observations reveal a complex hydrological system on the ice sheet's surface that are not well captured by these models. Yet, understanding the fate and impact of the meltwater on the ocean depends on knowing these temporal and spatial details. Unusually thick, near surface, ice lenses found in firn cores, most likely formed during very large recent melt events signify meltwater refreezing, but may also prevent further infiltration while facilitating runoff. Maps derived from remote sensing show how this runoff flows through an extensive network of supraglacial streams and lakes before it drains into the ice via moulins. Observations of discharge on the ice sheet surface and its margin provide evidence of runoff delays and retention before it is exported to the surrounding oceans. Here, trends and spatial patterns in ice sheet runoff will be examined by using model outputs from the regional surface mass balance model Modèle Atmosphérique Régional and compared with recent remotely sensed and field observations.

  1. Face-Sheet Quality Analysis and Thermo-Physical Property Characterization of OOA and Autoclave Panels

    Science.gov (United States)

    Miller, Sandi G.; Lort, Richard D., III; Zimmerman, Thomas J.; Sutter, James K.; Pelham, Larry I.; McCorkle, Linda S.; Scheiman, Daniel A.

    2012-01-01

    Increased application of polymer matrix composite (PMC) materials in large vehicle structures requires consideration of non-autoclave manufacturing technology. The NASA Composites for Exploration project, and its predecessor, Lightweight Spacecraft Structures and Materials project, were tasked with the development of materials and manufacturing processes for structures that will perform in a heavy-lift-launch vehicle environment. Both autoclave and out of autoclave processable materials were considered. Large PMC structures envisioned for such a vehicle included the payload shroud and the interstage connector. In this study, composite sandwich panels representing 1/16th segments of the barrel section of the Ares V rocket fairing were prepared as 1.8 m x 2.4 m sections of the 10 m diameter arc segment. IM7/977-3 was used as the face-sheet prepreg of the autoclave processed panels and T40-800B/5320-1 for the out of autoclave panels. The core was 49.7 kg/sq m (3.1 lb/cu ft (pcf)) aluminum honeycomb. Face-sheets were fabricated by automated tape laying 153 mm wide unidirectional tape. This work details analysis of the manufactured panels where face-sheet quality was characterized by optical microscopy, cured ply thickness measurements, acid digestion, and thermal analysis.

  2. Measuring Ice Sheet Height with ICESat-2

    Science.gov (United States)

    Walsh, K.; Smith, B.; Neumann, T.; Hancock, D.

    2015-12-01

    ICESat-2 is NASA's next-generation laser altimeter, designed to measure changes in ice sheet height and sea ice freeboard. Over the ice sheets, it will use a continuous repeat-track pointing strategy to ensure that it accurately measures elevation changes along a set of reference tracks. Over most of the area of Earth's ice sheets, ICESat-2 will provide coverage with a track-to-track spacing better than ~3 km. The onboard ATLAS instrument will use a photon-counting approach to provide a global geolocated photon point cloud, which is then converted into surface-specific elevation data sets. In this presentation, we will outline our strategy for taking the low-level photon point cloud and turning it into measurements posted at 20 m along-track for a set of pre-defined reference points by (1) selecting groups of photon events (PEs) around each along-track point, (2) refining the initial PE selection by fitting selected PEs with an along-track segment model and eliminating outliers to the model, (3) applying histogram-based corrections to the surface height based on the residuals to the along-track segment model, (4) calculate error estimates based on estimates of relative contributions of signal and noise PEs to the observed PE count, and (5) determining the final location and surface height of the along-track segment. These measurements are then corrected for short-scale (100-200 m) across-track surface topography around the reference points to develop a time series of land ice heights. The resulting data products will allow us to measure ice sheet elevation change with a point-for-point accuracy of a few centimeters over Earth's ice sheets.

  3. Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics.

    Science.gov (United States)

    Yamane, Masako; Yokoyama, Yusuke; Abe-Ouchi, Ayako; Obrochta, Stephen; Saito, Fuyuki; Moriwaki, Kiichi; Matsuzaki, Hiroyuki

    2015-04-24

    The Late Pliocene epoch is a potential analogue for future climate in a warming world. Here we reconstruct Plio-Pleistocene East Antarctic Ice Sheet (EAIS) variability using cosmogenic nuclide exposure ages and model simulations to better understand ice sheet behaviour under such warm conditions. New and previously published exposure ages indicate interior-thickening during the Pliocene. An ice sheet model with mid-Pliocene boundary conditions also results in interior thickening and suggests that both the Wilkes Subglacial and Aurora Basins largely melted, offsetting increased ice volume. Considering contributions from West Antarctica and Greenland, this is consistent with the most recent IPCC AR5 estimate, which indicates that the Pliocene sea level likely did not exceed +20 m on Milankovitch timescales. The inception of colder climate since ∼3 Myr has increased the sea ice cover and inhibited active moisture transport to Antarctica, resulting in reduced ice sheet thickness, at least in coastal areas.

  4. Semiconductor Manufacturing Final Air Toxics Rules Fact Sheets

    Science.gov (United States)

    This page contains a February 2003 fact sheet for the final NESHAP for Semiconductor Manufacturing. This page also contains a July 2008 fact sheet with information regarding the final amendments to the 2003 final rule for the NESHAP.

  5. Ice flow Modelling of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Nielsen, Lisbeth Tangaa

    simulations of the Greenland ice sheet using ice sheet models offers the possibility of deriving reconstructions of past ice sheet topography, flow and extent, consistent with the dynamics of ice flow and the imposed climate forcing. The large-scale response of the ice sheet modelled by such approaches can...... core derived temperature and precipitation histories have a long history of being used in studies of the past evolution of the Greenland ice sheet, acting as climatic forcing of the ice sheet models. However, the conversion from the isotopic records to past temperatures remain challenging, owing...... to both uncertain processes and depositional histories. Using five different temperature reconstructions derived from isotope records of Greenlandic ice cores, the influence of the paleo records on the simulated ice sheet was investigated using a high-resolution, large-scale ice sheet model (PISM...

  6. Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics

    Science.gov (United States)

    Poh, Gang Kai

    sheets than the dusk side. Using the Harris current sheet model, we determined the peak current sheet current density and reported an asymmetry pattern for peak current density consistent with observed asymmetries in current sheet thickness. We propose that enhancement of heavy ions in the dusk side current sheet, due to centrifugal acceleration and gradient-curvature drift of ions from the cusp and current sheet, provides a partial explanation of the dawn-dusk current sheet asymmetries observed in this study. Furthermore, our results are consistent with earlier studies on reconnection-related structures and phenomenon, which suggest that the asymmetries observed in this study are associated with the asymmetric nature of magnetotail reconnection at Mercury. We also report the possible observation of an Earth-like substorm current wedge in the near-Mercury magnetotail. We calculate the total current in the Hermean substorm current wedge and found that the current close via the conductive planetary core. The current closure mechanism may be similar to the Region 1 currents observed in an earlier study. From the above results, we conclude that the plasma processes occurring at Mercury are different from those at Earth due to difference in internal plasma composition, relative size of Mercury's magnetosphere and solar wind conditions at small heliospheric distances, despite many structural similarities in both magnetospheres. The results reported in this thesis have far-reaching implications for the physical processes in Mercury's magnetospheres and those of the other planets.

  7. An ice sheet model validation framework for the Greenland ice sheet

    Science.gov (United States)

    Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.; Howat, Ian M.; Neumann, Thomas; Saba, Jack; Tezaur, Irina; Guerber, Jeffrey; Chambers, Don P.; Evans, Katherine J.; Kennedy, Joseph H.; Lenaerts, Jan; Lipscomb, William H.; Perego, Mauro; Salinger, Andrew G.; Tuminaro, Raymond S.; van den Broeke, Michiel R.; Nowicki, Sophie M. J.

    2017-01-01

    We propose a new ice sheet model validation framework - the Cryospheric Model Comparison Tool (CmCt) - that takes advantage of ice sheet altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice sheet. We use realistic simulations performed with the Community Ice Sheet Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013, using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quantitative metrics for use in evaluating the different model simulations against the observations. We find that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin-scale and whole-ice-sheet-scale metrics, we find that simulations using both idealized conceptual models and dynamic, numerical models provide an equally reasonable representation of the ice sheet surface (mean elevation differences of digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CmCt, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice sheet models, when appropriately initialized and forced with the right boundary conditions, demonstrate a predictive skill with respect to observed dynamic changes that have occurred on Greenland over the past few decades. An extensible design will allow for continued use

  8. Residual stress measurement in silicon sheet by shadow moire interferometry

    Science.gov (United States)

    Kwon, Y.; Danyluk, S.; Bucciarelli, L.; Kalejs, J. P.

    1987-01-01

    A shadow moire interferometry technique has been developed to measure residual strain in thin silicon sheet. The curvature of a segment of sheet undergoing four-point bending is analyzed to include the applied bending moments, the in-plane residual stresses, and the 'end effect' of the sheet since it is of finite length. The technique is applied to obtain residual stress distributions for silicon sheet grown by the edge-defined film-fed growth technique.

  9. Causality in noncommutative two-sheeted space-times

    Science.gov (United States)

    Franco, Nicolas; Eckstein, Michał

    2015-10-01

    We investigate the causal structure of two-sheeted space-times using the tools of Lorentzian spectral triples. We show that the noncommutative geometry of these spaces allows for causal relations between the two sheets. The computation is given in detail when the sheet is a 2- or 4-dimensional globally hyperbolic spin manifold. The conclusions are then generalised to a point-dependent distance between the two sheets resulting from the fluctuations of the Dirac operator.

  10. Causality in noncommutative two-sheeted space-times

    CERN Document Server

    Franco, Nicolas

    2015-01-01

    We investigate the causal structure of two-sheeted space-times using the tools of Lorentzian spectral triples. We show that the noncommutative geometry of these spaces allows for causal relations between the two sheets. The computation is given in details when the sheet is a 2- or 4-dimensional globally hyperbolic spin manifold. The conclusions are then generalised to a point-dependent distance between the two sheets resulting from the fluctuations of the Dirac operator.

  11. Characterization of Chitosan Nanofiber Sheets for Antifungal Application

    OpenAIRE

    Mayumi Egusa; Ryo Iwamoto; Hironori Izawa; Minoru Morimoto; Hiroyuki Saimoto; Hironori Kaminaka; Shinsuke Ifuku

    2015-01-01

    Chitosan produced by the deacetylation of chitin is a cationic polymer with antimicrobial properties. In this study, we demonstrate the improvement of chitosan properties by nanofibrillation. Nanofiber sheets were prepared from nanofibrillated chitosan under neutral conditions. The Young’s modulus and tensile strength of the chitosan NF sheets were higher than those of the chitosan sheets prepared from dissolving chitosan in acetic acid. The chitosan NF sheets showed strong mycelial growth in...

  12. Effect of Temperature and Sheet Temper on Isothermal Solidification Kinetics in Clad Aluminum Brazing Sheet

    Science.gov (United States)

    Benoit, Michael J.; Whitney, Mark A.; Wells, Mary A.; Winkler, Sooky

    2016-09-01

    Isothermal solidification (IS) is a phenomenon observed in clad aluminum brazing sheets, wherein the amount of liquid clad metal is reduced by penetration of the liquid clad into the core. The objective of the current investigation is to quantify the rate of IS through the use of a previously derived parameter, the Interface Rate Constant (IRC). The effect of peak temperature and initial sheet temper on IS kinetics were investigated. The results demonstrated that IS is due to the diffusion of silicon (Si) from the liquid clad layer into the solid core. Reduced amounts of liquid clad at long liquid duration times, a roughened sheet surface, and differences in resolidified clad layer morphology between sheet tempers were observed. Increased IS kinetics were predicted at higher temperatures by an IRC model as well as by experimentally determined IRC values; however, the magnitudes of these values are not in good agreement due to deficiencies in the model when applied to alloys. IS kinetics were found to be higher for sheets in the fully annealed condition when compared with work-hardened sheets, due to the influence of core grain boundaries providing high diffusivity pathways for Si diffusion, resulting in more rapid liquid clad penetration.

  13. Spray visualization by laser sheet tomography; Laser sheet ni yoru funmu danmen no kashikaho

    Energy Technology Data Exchange (ETDEWEB)

    Oda, T.; Hiroyasu, H. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

    1996-07-21

    Laser sheet tomography was applied to the visualization of the cross section of a spray. In this method, fluorescent dye, eosine-Y(C20H6Br4Na2O), was used at a concentration of 10 g/l of the injectant, water, and the light source which illuminated the spray was a Nd: YAG laser (532 wavelength, 20ns pulse width) in laser sheet tomography. The thickness of the laser sheet which was scattered by the spray was measured to elucidate the effect of the concentration of fluorescent dye in the injected liquid. In the case of water without eosine-Y, multiscattered light-illuminated drops were observed outside of the laser sheet therefore the thickness of the laser sheet increased. However, in the case of water with eosine-Y, there were few drops which were illuminated by the multiscattered light, and only drops which existed within the laser sheet scattered green laser light and emitted the yellow fluorescent light of eosine-Y. 11 refs., 10 figs., 2 tabs.

  14. Phase analysis of fume during arc weld brazing of steel sheets with protective coatings

    Directory of Open Access Journals (Sweden)

    J. Matusiak

    2016-04-01

    Full Text Available The article presents the results of research of the phase identification and of the quantitative phase analysis of fume generated during Cold Metal Transfer (CMT, ColdArc and Metal Inert Gas / Metal Active Gas (MIG / MAG weld brazing. Investigations were conducted for hot - dip coated steel sheets with zinc (Zn and zinc-iron (Zn - Fe alloy coatings. Arc shielding gases applied during the research-related tests were Ar + O2, Ar + CO2, Ar + H2 and Ar + CO2 + H2 gas mixtures. The analysis of the results covers the influence of the chemical composition of shielding gas on the chemical composition of welding fume.

  15. Investigation on Superplasticity in SiCp/2024 Cold Rolling Sheet after Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Bol(u) XIAO; Zongyi MA; Jing BI

    2003-01-01

    High strain rate superplastic deformation behavior of powder metallurgy (PM) processed 17 vol. pct SiCp/2024 Al composite sheet after heat treatment was investigated over a range of temperature from 753 to 833 K. At 813 K,a maximum elongation of 259% was discovered at a strain rate of 10-1 s-1. The activation energy was closed to that for lattice diffusion of Al and increased at temperature upon incipient melting temperature. The mechanism of superplastic deformation for present composites was attributed to lattice diffusion controlled grain boundary sliding.

  16. Electromagnetic augmentation for casting of thin metal sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    1989-01-01

    Thin metal sheets are cast by magnetically levitating molten metal deposited in a mold within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled by the water-cooled walls of the mold to form a solid metal sheet. A conducting shield is electrically coupled to the molten metal sheet to provide a return path for eddy currents induced in the metal sheet by the current in the AC conducting coils. In another embodiment, a DC conducting coil is coupled to the metal sheet for providing a direct current therein which interacts with the magnetic field to levitate the moving metal sheet. Levitation of the metal sheet in both molten and solid forms reduces its contact pressure with the mold walls while maintaining sufficient engagement therebetween to permit efficient conductive cooling by the mold through which a coolant fluid may be circulated. The magnetic fields associated with the currents in the aforementioned coils levitate the molten metal sheet while the mold provides for its lateral and vertical confinement. A leader sheet having electromagnetic characteristics similar to those of the molten metal sheet is used to start the casing process and precedes the molten metal sheet through the yoke/coil arrangement and mold and forms a continuous sheet therewith. The yoke/coil arrangement may be either U-shaped with a single racetrack coil or may be rectangular with a pair of spaced, facing bedstead coils.

  17. Crib Sheets and Exam Performance in a Data Structures Course

    Science.gov (United States)

    Hamouda, Sally; Shaffer, Clifford A.

    2016-01-01

    In this paper, we study the relationship between the use of "crib sheets" or "cheat sheets" and performance on in-class exams. Our extensive survey of the existing literature shows that it is not decisive on the questions of when or whether crib sheets actually help students to either perform better on an exam or better learn…

  18. 49 CFR 1243.2 - Condensed balance sheet.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Condensed balance sheet. 1243.2 Section 1243.2... § 1243.2 Condensed balance sheet. Commencing with reports for the 3 months beginning January 1, 1972, and... hereby, required to compile and file quarterly reports of balance sheet items in accordance...

  19. Processing and Characterization of Carbon Nanotube Composites

    Science.gov (United States)

    Can, Roberto J.; Grimsley, Brian W.; Czabaj, Michael W.; Siochi, Emilie J.; Hull, Brandon

    2014-01-01

    Recent advances in the synthesis of large-scale quantities of carbon nanotubes (CNT) have provided the opportunity to study the mechanical properties of polymer matrix composites using these novel materials as reinforcement. Nanocomp Technologies, Inc. currently supplies large sheets with dimensions up to 122 cm x 244 cm containing both single-wall and few-wall CNTs. The tubes are approximately 1 mm in length with diameters ranging from 8 to 12 nm. In the present study being conducted at NASA Langley Research Center (LaRC), single and multiple layers of CNT sheets were infused or coated with various polymer solutions that included commercial toughened-epoxies and bismaleimides, as well as a LaRC developed polyimide. The resulting CNT composites were tested in tension using a modified version of ASTM D882-12 to determine their strength and modulus values. The effects of solvent treatment and mechanical elongation/alignment of the CNT sheets on the tensile performance of the composite were determined. Thin composites (around 50 wt% CNT) fabricated from acetone condensed and elongated CNT sheets with either a BMI or polyimide resin solution exhibited specific tensile moduli approaching that of toughened epoxy/ IM7 carbon fiber unidirectional composites.

  20. Deformation Behaviors of HIPped Foil Compared with Those of Sheet Titanium Alloys

    Science.gov (United States)

    Castelli, Michael G.

    1999-01-01

    Micromechanics-based modeling of composite material behaviors requires an accurate assessment of the constituent properties and behaviors. For the specific case of continuous-fiber-reinforced metal matrix composites (MMC's) manufactured from a foil/fiber/foil process, much emphasis has been placed on characterizing foil-based matrix materials that have been fabricated in the same way as the composite. Such materials are believed to yield mechanical properties and behaviors that are representative of the matrix constituent within the composite (in situ matrix). Therefore, these materials are desired for micromechanics modeling input. Unfortunately, such foils are extremely expensive to fabricate and procure because of the labor-intensive rolling process needed to produce them. As a potential solution to this problem that would maintain appropriately representative in situ properties, the matrix constituent could be characterized with sheet-based materials, which are considerably less expensive to manufacture than foils, are more readily procured, and result in fewer plies to obtain a desired panel thickness. The critical question is, however, does the consolidated sheet material exhibit the same properties and behaviors as do the consolidated foils? Researchers at NASA Lewis Research Center's Life Prediction Branch completed a detailed experimental investigation to answer this question for three titanium alloys commonly used in metal matrix composite form.

  1. Rewriting Ice Sheet "Glacier-ology"

    Science.gov (United States)

    Bindschadler, R.

    2006-12-01

    The revolution in glaciology driven by the suite of increasingly sophisticated satellite instruments has been no more extreme than in the area of ice dynamics. Years ago, glaciologists were (probably unwittingly) selective in what properties of mountain glaciers were also applied to ice sheets. This reinforced the view that they responded slowly to their environment. Notions of rapid response driven by the ideas of John Mercer, Bill Budd and Terry Hughes were politely rejected by the centrists of mainstream glaciological thought. How the tables have turned--and by the ice sheets themselves, captured in the act of rapidly changing by modern remote sensors! The saw-toothed record of sea-level change over past glacial-interglacial cycles required the existence of rapid ice loss processes. Satellite based observations, supported by hard-earned field observations have extended the time scale over which ice sheets can suddenly change to ever shorter intervals: from centuries, to decades, to years to even minutes. As changes continue to be observed, the scientific community is forced to consider new or previously ignored processes to explain these observations. The penultimate goal of ice-sheet dynamics is to credibly predict the future of both the Greenland and Antarctic ice sheets. In this important endeavor, there is no substitute for our ability to observe. Without the extensive data sets provided by remote sensing, numerical models can be neither tested nor improved. The impact of remote sensing on our existing ability to predict the future must be compared to our probable state of knowledge and ability were these data never collected. Among many satellite observed phenomena we would be largely or wholly ignorant of are the recent acceleration of ice throughout much of coastal Greenland; the sudden disintegration of multiple ice shelves along the Antarctic Peninsula; and the dramatic thinning and acceleration of the Amundsen Sea sector of West Antarctica. These

  2. Ice sheet systems and sea level change.

    Science.gov (United States)

    Rignot, E. J.

    2015-12-01

    Modern views of ice sheets provided by satellites, airborne surveys, in situ data and paleoclimate records while transformative of glaciology have not fundamentally changed concerns about ice sheet stability and collapse that emerged in the 1970's. Motivated by the desire to learn more about ice sheets using new technologies, we stumbled on an unexplored field of science and witnessed surprising changes before realizing that most were coming too fast, soon and large. Ice sheets are integrant part of the Earth system; they interact vigorously with the atmosphere and the oceans, yet most of this interaction is not part of current global climate models. Since we have never witnessed the collapse of a marine ice sheet, observations and exploration remain critical sentinels. At present, these observations suggest that Antarctica and Greenland have been launched into a path of multi-meter sea level rise caused by rapid climate warming. While the current loss of ice sheet mass to the ocean remains a trickle, every mm of sea level change will take centuries of climate reversal to get back, several major marine-terminating sectors have been pushed out of equilibrium, and ice shelves are irremediably being lost. As glaciers retreat from their salty, warm, oceanic margins, they will melt away and retreat slower, but concerns remain about sea level change from vastly marine-based sectors: 2-m sea level equivalent in Greenland and 23-m in Antarctica. Significant changes affect 2/4 marine-based sectors in Greenland - Jakobshavn Isb. and the northeast stream - with Petermann Gl. not far behind. Major changes have affected the Amundsen Sea sector of West Antarctica since the 1980s. Smaller yet significant changes affect the marine-based Wilkes Land sector of East Antarctica, a reminder that not all marine-based ice is in West Antarctica. Major advances in reducing uncertainties in sea level projections will require massive, interdisciplinary efforts that are not currently in place

  3. The Rapid Ice Sheet Change Observatory (RISCO)

    Science.gov (United States)

    Morin, P.; Howat, I. M.; Ahn, Y.; Porter, C.; McFadden, E. M.

    2010-12-01

    The recent expansion of observational capacity from space has revealed dramatic, rapid changes in the Earth’s ice cover. These discoveries have fundamentally altered how scientists view ice-sheet change. Instead of just slow changes in snow accumulation and melting over centuries or millennia, important changes can occur in sudden events lasting only months, weeks, or even a single day. Our understanding of these short time- and space-scale processes, which hold important implications for future global sea level rise, has been impeded by the low temporal and spatial resolution, delayed sensor tasking, incomplete coverage, inaccessibility and/or high cost of data available to investigators. New cross-agency partnerships and data access policies provide the opportunity to dramatically improve the resolution of ice sheet observations by an order of magnitude, from timescales of months and distances of 10’s of meters, to days and meters or less. Advances in image processing technology also enable application of currently under-utilized datasets. The infrastructure for systematically gathering, processing, analyzing and distributing these data does not currently exist. Here we present the development of a multi-institutional, multi-platform observatory for rapid ice change with the ultimate objective of helping to elucidate the relevant timescales and processes of ice sheet dynamics and response to climate change. The Rapid Ice Sheet Observatory (RISCO) gathers observations of short time- and space-scale Cryosphere events and makes them easily accessible to investigators, media and general public. As opposed to existing data centers, which are structured to archive and distribute diverse types of raw data to end users with the specialized software and skills to analyze them, RISCO focuses on three types of geo-referenced raster (image) data products in a format immediately viewable with commonly available software. These three products are (1) sequences of images

  4. West Antarctic Ice Sheet retreat driven by Holocene warm water incursions

    Science.gov (United States)

    Hillenbrand, Claus-Dieter; Smith, James A.; Hodell, David A.; Greaves, Mervyn; Poole, Christopher R.; Kender, Sev; Williams, Mark; Andersen, Thorbjørn Joest; Jernas, Patrycja E.; Elderfield, Henry; Klages, Johann P.; Roberts, Stephen J.; Gohl, Karsten; Larter, Robert D.; Kuhn, Gerhard

    2017-07-01

    Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) incursions onto the West Antarctic continental shelf cause melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their ocean-induced thinning is driving Antarctic ice-sheet retreat today. Here we present a multi-proxy data based reconstruction of variability in CDW inflow to the Amundsen Sea sector, the most vulnerable part of the West Antarctic Ice Sheet, during the Holocene epoch (from 11.7 thousand years ago to the present). The chemical compositions of foraminifer shells and benthic foraminifer assemblages in marine sediments indicate that enhanced CDW upwelling, controlled by the latitudinal position of the Southern Hemisphere westerly winds, forced deglaciation of this sector from at least 10,400 years ago until 7,500 years ago—when an ice-shelf collapse may have caused rapid ice-sheet thinning further upstream—and since the 1940s. These results increase confidence in the predictive capability of current ice-sheet models.

  5. Ranking Beta Sheet Topologies of Proteins

    DEFF Research Database (Denmark)

    Fonseca, Rasmus; Helles, Glennie; Winter, Pawel

    2010-01-01

    One of the challenges of protein structure prediction is to identify long-range interactions between amino acids.  To reliably predict such interactions, we enumerate, score and rank all beta-topologies (partitions of beta-strands into sheets, orderings of strands within sheets and orientations...... of paired strands) of a given protein.  We show that the beta-topology corresponding to the native structure is, with high probability, among the top-ranked. Since full enumeration is very time-consuming, we also suggest a method to deal with proteins with many beta-strands. The results reported...... in this paper are highly relevant for ab initio protein structure prediction methods based on decoy generation. The top-ranked beta-topologies can be used to find initial conformations from which conformational searches can be started. They can also be used to filter decoys by removing those with poorly...

  6. Energetic electron spectra in Saturn's plasma sheet

    Science.gov (United States)

    Carbary, J. F.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Krupp, N.

    2011-07-01

    The differential spectra of energetic electrons (27-400 keV) in Saturn's plasma sheet can be characterized by power law or kappa distributions. Using all available fluxes from 2005 to 2010, fits to these distributions reveal a striking and consistent pattern of radial dependence in Saturn's plasma sheet (∣z∣ constant throughout the Cassini mission. Inward of about 10 RS, the presence of the electron radiation belts and losses of lower-energy electrons to the gas and grain environment give rise to the very hard spectra in the inner magnetosphere, while the hard spectra in the outer magnetosphere may derive from auroral acceleration at high latitudes. The gradual softening of the spectra from 20 to 10 RS is explained by inward radial diffusion.

  7. Microscale Flow Dynamics of Ribbons and Sheets

    CERN Document Server

    Montenegro-Johnson, Thomas D; Lauga, Eric

    2016-01-01

    Numerical study of the hydrodynamics of thin sheets and ribbons presents difficulties associated with resolving multiple length scales. To circumvent these difficulties, asymptotic methods have been developed to describe the dynamics of slender fibres and ribbons. However, such theories entail restrictions on the shapes that can be studied, and often break down in regions where standard boundary element methods are still impractical. In this paper we develop a regularised stokeslet method for ribbons and sheets in order to bridge the gap between asymptotic and boundary element methods. The method is validated against the analytical solution for plate ellipsoids, as well as the dynamics of ribbon helices and an experimental microswimmer. We then demonstrate the versatility of this method by calculating the flow around a double helix, and the swimming dynamics of a microscale "magic carpet".

  8. Confocal multiview light-sheet microscopy

    Science.gov (United States)

    Medeiros, Gustavo de; Norlin, Nils; Gunther, Stefan; Albert, Marvin; Panavaite, Laura; Fiuza, Ulla-Maj; Peri, Francesca; Hiiragi, Takashi; Krzic, Uros; Hufnagel, Lars

    2015-01-01

    Selective-plane illumination microscopy has proven to be a powerful imaging technique due to its unsurpassed acquisition speed and gentle optical sectioning. However, even in the case of multiview imaging techniques that illuminate and image the sample from multiple directions, light scattering inside tissues often severely impairs image contrast. Here we combine multiview light-sheet imaging with electronic confocal slit detection implemented on modern camera sensors. In addition to improved imaging quality, the electronic confocal slit detection doubles the acquisition speed in multiview setups with two opposing illumination directions allowing simultaneous dual-sided illumination. Confocal multiview light-sheet microscopy eliminates the need for specimen-specific data fusion algorithms, streamlines image post-processing, easing data handling and storage. PMID:26602977

  9. Models for polythermal ice sheets and glaciers

    Science.gov (United States)

    Hewitt, Ian J.; Schoof, Christian

    2017-02-01

    Polythermal ice sheets and glaciers contain both cold ice and temperate ice. We present two new models to describe the temperature and water content of such ice masses, accounting for the possibility of gravity- and pressure-driven water drainage according to Darcy's law. Both models are based on the principle of energy conservation; one additionally invokes the theory of viscous compaction to calculate pore water pressure, and the other involves a modification of existing enthalpy gradient methods to include gravity-driven drainage. The models self-consistently predict the evolution of temperature in cold ice and of water content in temperate ice. Numerical solutions are described, and a number of illustrative test problems are presented, allowing comparison with existing methods. The suggested models are simple enough to be incorporated in existing ice-sheet models with little modification.

  10. The state of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Simonsen, Sebastian Bjerregaard

    Firn is defined as snow that has survived a melt season and provides the link between the high-frequency variability of the atmosphere to the ”slower” reacting ice sheet.In this thesis, firn is described by a theoretical and statistical approach to accommodate the variability in observed firn...... compaction on ice sheet scales. The modeling objectives are multiple and aim at estimating the contribution from the firn to the observed volume change of the GrIS and to the diffusion of stable water isotopes. The firn modeling then provides crucial information on total mass balance of the Gr......IS and the paleo-temperature reconstructions retrieved from ice cores.The dynamical firn model developed in this thesis explains13 % of the observed volume change of the GrIS from 2003-2008, without contributing to the global sea-level rise. This emphasizes the need for well constraint firn-compaction models. Here...

  11. Growth of silicon sheets from metallurgical-grade silicon

    Science.gov (United States)

    Ciszek, T.; Schietzelt, M.; Kazmerski, L. L.; Hurd, J. L.; Fernelius, B.

    1981-05-01

    Impure silicon is difficult to solidify in sheet form because of morphological proturberances which may result from constitutional supercooling. Sheet growth methods which require a specific crystallographic orientation or which are characterized by a narrow melt meniscus are most affected by this problem. The edge-supported pulling technique was applied to sheet growth of metallurgical grade silicon and DAR (Direct Arc Reactor) silicon. The 7 mm meniscus height associated with this technique allowed the growth of 5 cm wide sheets from both materials. In each case, the sheets were p-type.

  12. Effective electromagnetic forces in thin sheet metal specimen

    Directory of Open Access Journals (Sweden)

    Langstädtler L.

    2015-01-01

    Full Text Available Electromagnetic forming is mainly investigated for the macro world as the body forces in this high speed process are decreasing with the volume of the specimen. For micro metal sheets different effects are observed which make an analysis of the acting forces more difficult. Hence, the validity of process simulations for electromagnetic forming is still limited. In this research the effective electromagnetic force on thin EN AW-1050A (Al99.5 sheet metals is investigated by varying the loading energy EC, the ration sR between sheet thickness and skin depth, the sheets width b and the distance dC between passive tool and sheet metal.

  13. Research progress of aluminum alloy automotive sheet and application technology

    Institute of Scientific and Technical Information of China (English)

    Ma Mingtu; You Jianghai; Lu Hongzhou; Wang Zhiwen

    2012-01-01

    Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to automotive industry are listed. Based on the author's knowledge and recognition and research progress presently, the important re- search contents about aluminum alloy automotive sheet are emphasized. Reducing cost and price of sheet and going deeply into application research are the main work for expending the application of aluminum alloy automotive sheet in the automobile.

  14. Drift modes of a quasi-two-dimensional current sheet

    Energy Technology Data Exchange (ETDEWEB)

    Artemyev, A. V.; Malova, Kh. V.; Popov, V. Yu.; Zelenyi, L. M. [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2012-03-15

    Stability of a plasma configuration consisting of a thin one-dimensional current sheet embedded into a two-dimensional background current sheet is studied. Drift modes developing in plasma as unstable waves along the current direction are considered. Dispersion relations for kink and sausage perturbation modes are obtained depending on the ratio of parameters of thin and background current sheets. It is shown that the existence of the background sheet results in a decrease in the instability growth rates and a significant increase in the perturbation wavelengths. The role of drift modes in the excitation of oscillations observed in the current sheet of the Earth's magnetotail is discussed.

  15. Technology design of composite parts

    OpenAIRE

    K. Karjust; R. Küttner; M. Pohlak

    2007-01-01

    Purpose: Purpose of this paper is to optimize the design of the manufacturing technology process of large composite plastic products. One of the key problems is how to integrate computer-based product design and planning of the technology process.Design/methodology/approach: In the current study the Neural Network meta-modelling technique has been used. The optimization of the plastic sheet and its strengthening layer thickness has been performed using the surrogate design model. For modeling...

  16. Nuclear Data Sheets for A=150

    Energy Technology Data Exchange (ETDEWEB)

    Basu, S.K.; Sonzogni, A.A.

    2013-04-15

    The experimental results from the various reaction and decay studies leading to nuclides in the A=150 mass chain have been reviewed. These data are summarized and presented, together with the adopted level schemes and properties, for the nuclides from Cs(Z=55) through Lu(Z=71). This evaluation replaces the previous evaluation by E. der Mateosian and J. K. Tuli (1995De28), which appeared in Nuclear Data Sheets 75, 827 (1995)

  17. Ice Sheet System Model as Educational Entertainment

    Science.gov (United States)

    Perez, G.

    2013-12-01

    Understanding the importance of polar ice sheets and their role in the evolution of Sea Level Rise (SLR), as well as Climate Change, is of paramount importance for policy makers as well as the public and schools at large. For example, polar ice sheets and glaciers currently account for 1/3 of the SLR signal, a ratio that will increase in the near to long-term future, which has tremendous societal ramifications. Consequently, it is important to increase awareness about our changing planet. In our increasingly digital society, mobile and web applications are burgeoning venues for such outreach. The Ice Sheet System Model (ISSM) is a software that was developed at the Jet Propulsion Laboratory/CalTech/NASA, in collaboration with University of California Irvine (UCI), with the goal of better understanding the evolution of polar ice sheets. It is a state-of-the-art framework, which relies on higher-end cluster-computing to address some of the aforementioned challenges. In addition, it is a flexible framework that can be deployed on any hardware; in particular, on mobile platforms such as Android or iOS smart phones. Here, we look at how the ISSM development team managed to port their model to these platforms, what the implications are for improving how scientists disseminate their results, and how a broader audience may familiarize themselves with running complex climate models in simplified scenarios which are highly educational and entertaining in content. We also look at the future plans toward a web portal fully integrated with mobile technologies to deliver the best content to the public, and to provide educational plans/lessons that can be used in grades K-12 as well as collegiate under-graduate and graduate programs.

  18. Quadric Resistive Sheet Profile for Wideband Antennas

    Directory of Open Access Journals (Sweden)

    Z. Raida

    2007-09-01

    Full Text Available A new type of a nonreflecting resistive dipole antenna with quadric continuous resistivity profile is presented in this paper. The antenna is mathematically described and compared with the antenna originally proposed by Wu and King. The verification of a proposed theory and the comparison between Wu-King and quadric profile are carried out by simulation models that were designed for this purpose. The attention is turned to the proper attenuation of a wave excited on the resistive sheet, especially.

  19. Elastohydrodynamics of contact in adherent sheets

    OpenAIRE

    Carlson, Andreas; Mandre, Shreyas; Mahadevan, L

    2015-01-01

    Adhesive contact between a thin elastic sheet and a substrate in a liquid environment arises in a range of biological, physical and technological applications. By considering the dynamics of this process that naturally couples fluid flow, long wavelength elastic deformations and microscopic adhesion, and solving the resulting partial differential equation numerically, we uncover the short-time dynamics of the onset of adhesion and the long-time dynamics of a steady propagating adhesion front....

  20. Nuclear Data Sheets for A = 183

    Energy Technology Data Exchange (ETDEWEB)

    Baglin, Coral M.

    2016-05-15

    Evaluated nuclear structure and decay data for all nuclides with mass number A=183 (Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb) are presented here. At, Po and Fr have not yet been observed, but for prediction of ground state and/or isomer properties see, e.g., 2015Bh08 (At, Fr), 2013Ba41 (Tl), 2013Ho05 (Po). This evaluation includes structure and decay data information available by 15 April 2015 and supersedes that by R.B. Firestone published in Nuclear Data Sheets65, 589 (1992) (literature cutoff 9 January 1991), and subsequent revisions by C.M. Baglin for {sup 183}Au in ENSDF database (literature cutoff 13 March 1999), {sup 183}Hg in Nuclear Data Sheets91, 117 (2000) (literature cutoff 25 September 2000), {sup 183}Tl in Nuclear Data Sheets95, 49 (2002) (literature cutoff 1 January 2002) and {sup 183}Pb in ENSDF (literature cutoff 6 January 2003). Since the prior Nuclear Data Sheets publication of this mass chain: {sup 183}Yb (2012Ku26) and {sup 183}Pb (2006An11, 2006Se18, 2007De09, 2009Se13) have been observed; our knowledge of high–spin states has been significantly expanded for {sup 183}Ta (2009Sh17), {sup 183}W (1999Sa60), {sup 183}Re (1998Ha51, 2001Sh41), {sup 183}Au (2002Jo18, 2005So01) and {sup 183}Tl (2001Mu26, 2004Ra28); a large amount of new structure information for {sup 183}W has been obtained from transfer reactions (1997Pr02, 2011Bo09), (n,n'γ) (1993Pr09) and thermal neutron capture (1993Pr09, 1997Pr02, 2011Bo09, 2014Hu02), as well as from the two–photon cascade study by 2005Su29.

  1. Wind Powering America Initiative (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2011-01-01

    The U.S. Department of Energy's Wind Powering America initiative engages in technology market acceptance, barrier reduction, and technology deployment support activities. This fact sheet outlines ways in which the Wind Powering America team works to reduce barriers to appropriate wind energy deployment, primarily by focusing on six program areas: workforce development, communications and outreach, stakeholder analysis and resource assessment, wind technology technical support, wind power for Native Americans, and federal sector support and collaboration.

  2. Utilization of the terrestrial cyanobacterial sheet

    Science.gov (United States)

    Katoh, Hiroshi; Tomita-Yokotani, Kaori; Furukawa, Jun; Kimura, Shunta; Yamaguchi, Yuji; Takenaka, Hiroyuki; Kohno, Nobuyuki

    2016-07-01

    The terrestrial nitrogen-fixing cyanobacterium, Nostoc commune, is living ranging from polar to desert. N. commune makes visible colonies composed extracellular polymeric substances. N. commune has expected to utilize for agriculture, food and terraforming cause of its extracellular polysaccharide, desiccation tolerance and nitrogen fixation. To exhibit the potential abilities, the N. commune sheet is made to use convenient and evaluated by plant growth and radioactive accumulation. We will discuss utilization of terrestrial cyanobacteria under closed environment.

  3. Nuclear Data Sheets for A = 183

    Science.gov (United States)

    Baglin, Coral M.

    2016-05-01

    Evaluated nuclear structure and decay data for all nuclides with mass number A=183 (Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb) are presented here. At, Po and Fr have not yet been observed, but for prediction of ground state and/or isomer properties see, e.g., 2015Bh08 (At, Fr), 2013Ba41 (Tl), 2013Ho05 (Po). This evaluation includes structure and decay data information available by 15 April 2015 and supersedes that by R.B. Firestone published in Nuclear Data Sheets65, 589 (1992) (literature cutoff 9 January 1991), and subsequent revisions by C.M. Baglin for 183Au in ENSDF database (literature cutoff 13 March 1999), 183Hg in Nuclear Data Sheets91, 117 (2000) (literature cutoff 25 September 2000), 183Tl in Nuclear Data Sheets95, 49 (2002) (literature cutoff 1 January 2002) and 183Pb in ENSDF (literature cutoff 6 January 2003). Since the prior Nuclear Data Sheets publication of this mass chain: 183Yb (2012Ku26) and 183Pb (2006An11, 2006Se18, 2007De09, 2009Se13) have been observed; our knowledge of high-spin states has been significantly expanded for 183Ta (2009Sh17), 183W (1999Sa60), 183Re (1998Ha51, 2001Sh41), 183Au (2002Jo18, 2005So01) and 183Tl (2001Mu26, 2004Ra28); a large amount of new structure information for 183W has been obtained from transfer reactions (1997Pr02, 2011Bo09), (n,n'γ) (1993Pr09) and thermal neutron capture (1993Pr09, 1997Pr02, 2011Bo09, 2014Hu02), as well as from the two-photon cascade study by 2005Su29.

  4. V2O5 nanofibre sheet actuators

    Science.gov (United States)

    Gu, Gang; Schmid, Michael; Chiu, Po-Wen; Minett, Andrew; Fraysse, Jerôme; Kim, Gyu-Tae; Roth, Siegmar; Kozlov, Mikhail; Muñoz, Edgar; Baughman, Ray H.

    2003-05-01

    Vanadium oxides, such as V2O5, are promising for lithium-ion batteries, catalysis, electrochromic devices and sensors. Vanadium oxides were proposed more than a decade ago for another redox-dependent application: the direct conversion of electrical energy to mechanical energy in actuators (artificial muscles). Although related conducting polymer and carbon nanotube actuators have been demonstrated, electromechanical actuators based on vanadium oxides have not be realized. V2O5 nanofibres and nanotubes provide the potential advantages of low-cost synthesis by sol-gel routes and high charging capacity and long cycle life. Here, we demonstrate electromechanical actuation for obtained high modulus V2O5 sheets comprising entangled V2O5 nanofibres. The high surface area of these V2O5 sheets facilitates electrochemical charge injection and intercalation that causes the electromechanical actuation. We show that the V2O5 sheets provide high Young's modulus, high actuator-generated stress, and high actuator stroke at low applied voltage.

  5. Laser cutting of sheets for Tailored Blanks

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    1999-01-01

    Over the past few years there has been an enormous increase in the use of tailored blanks, especially in the automotive industry. Often the sheets for tailored blanks are shear cut, but results have been reported that the allowable sheet gap distance should not exceed 0.1 mm in order to obtain...... sound welds. Laser cutting the sheets may therefore be an alternative to shear cutting, if the cut kerf squareness can be kept below 0.05 mm.In a number of systematic laboratory experiments the effects of the major process parameters in laser cutting have been investigated. Each cut was quantified...... by the squareness, the surface roughness and the burr height. Mild steel as well as high strength steel with and with out galvanisation with thickness' of 0.7(5) and 1.25 were used.In the tests the difference in cut quality between a 5" and a 7.5" focusing lens were tested and the effect of using pulsed mode laser...

  6. Local Laser Heat Treatments of Steel Sheets

    Science.gov (United States)

    Järvenpää, A.; Jaskari, M.; Hietala, M.; Mäntyjärvi, K.

    In this work UHS structural and abrasion resistant (AR) steels were heat treated with a single 4 kW Yb: YAG-laser beam. Aim of the softening heat treatments was to enhance the formability locally with minimized strength lose. 1.8 mm thick B24CR boron steel was used for hardening tests. Study presents the possibilities and limitations in laser processing showing that a single laser beam is suitable for heat treating of sheets through the whole cross-section up to the thickness of 6 mm. In the case of the 6 mm thick sheets, the achieved maximum temperature in the cross-section varies as a function of the depth. Consequently, the microstructure and mechanical properties differ between the surfaces and the center of the cross-section (layered microstructure). For better understanding, all layers were tested in tensile tests. The 10 mm thick sheet was heat treated separately on the both surfaces by heating to a lower temperature range to produce a shallow tempered layer. The tensile and bendability tests as well as hardness measurements indicated that laser heat treatment can be used to highly improve the bendability locally without significant strength losses. Laser process has been optimized by transverse scanning movement and with a simple FE-model.

  7. Plasma Relaxation Dynamics Moderated by Current Sheets

    Science.gov (United States)

    Dewar, Robert; Bhattacharjee, Amitava; Yoshida, Zensho

    2014-10-01

    Ideal magnetohydrodynamics (IMHD) is strongly constrained by an infinite number of microscopic constraints expressing mass, entropy and magnetic flux conservation in each infinitesimal fluid element, the latter preventing magnetic reconnection. By contrast, in the Taylor-relaxed equilibrium model all these constraints are relaxed save for global magnetic flux and helicity. A Lagrangian is presented that leads to a new variational formulation of magnetized fluid dynamics, relaxed MHD (RxMHD), all static solutions of which are Taylor equilibrium states. By postulating that some long-lived macroscopic current sheets can act as barriers to relaxation, separating the plasma into multiple relaxation regions, a further generalization, multi-relaxed MHD (MRxMHD), is developed. These concepts are illustrated using a simple two-region slab model similar to that proposed by Hahm and Kulsrud--the formation of an initial shielding current sheet after perturbation by boundary rippling is calculated using MRxMHD and the final island state, after the current sheet has relaxed through a reconnection sequence, is calculated using RxMHD. Australian Research Council Grant DP110102881.

  8. In situ preparation of (BiO)2CO3/BiOBr sheet-on-sheet heterojunctions with enhanced visible light photocatalytic activity

    Science.gov (United States)

    Gao, Lin; Li, Xiao; Zhao, Jinyan; Zhang, Xin; Zhang, Xuhong; Yu, Haitao

    2017-09-01

    (BiO)2CO3/BiOBr sheet-on-sheet nanocomposites with different (BiO)2CO3 contents were synthesized via a in situ bubbling method and characterized by XRD, XPS, SEM, HRTEM, N2 adsorption-desorption, UV-vis DRS, PL, photocurrent and EIS. The photocatalytic activities of these samples were evaluated by degradation of methylene blue (MB) and Rhodamine B (RhB) under visible light irradiation. The results showed that the (BiO)2CO3/BiOBr composites displayed higher photocatalytic activity than the pristine (BiO)2CO3 and BiOBr. The 15 wt% (BiO)2CO3/BiOBr showed the highest photocatalytic activity under visible light irradiation. The enhanced photocatalytic activity of (BiO)2CO3/BiOBr composites could be attributed to the well-matched band structure and intimate contact interfaces between (BiO)2CO3 and BiOBr, which led to the effective transfer and separation of the photogenerated charge carriers. A possible photocatalytic mechanism for the (BiO)2CO3/BiOBr composites was also proposed based on the experimental results.

  9. Generated photocatalytic performance of h-BN sheet by coupling with reduced graphene oxide/fluorid: A DFT study

    Science.gov (United States)

    Lu, Baichuan; Jia, Jun; Guo, Fengjuan; Li, Dongyang; Zhao, Yunhao; Zhao, Xian; Gao, Hongtao

    2017-09-01

    First-principles calculation based on density functional theory (DFT) was performed to investigate the enhanced photocatalytic mechanism and electronic properties of hexagonal boron nitride (h-BN) sheet by coupling with reduced graphene oxide (RGO) or reduced graphene fluorid (RGF). It is demonstrated that the combination of h-BN with RGO(F) is thermodynamically favorable. The spatial configurations of O and F atoms played a key role in modifying the electronic structure and properties of h-BN/RGO(F) composites. The interaction between h-BN and RGO(F) sheets caused charge accumulation on the side of h-BN layer and charge depletion on the lower side of RGO(F) sheet. There formed a heterjunction between the interface, which could improve the separation efficiency of photogenerated carriers and inhibit their combination. Both valence band edge and conduction band edge positions of h-BN/RGO(F) composites were characterized to illustrate the enhanced oxidation-reduction performance mechanism. The theoretical investigation could provide valuable information for thoroughly understanding the mechanism of the exceptional performance of h-BN/RGO(F) composites compared to the h-BN sheet.

  10. Simulations of the Scandinavian ice sheet and its subsurface conditions

    Energy Technology Data Exchange (ETDEWEB)

    Boulton, G.S.; Caban, P.; Hulton, N. [Edinburgh Univ. (United Kingdom). Dept of Geology and Geophysics

    1999-12-01

    An ice sheet model has been applied to an approximate flow line through the area of the Fennoscandian ice sheet. The modelled ice sheet fluctuations have been matched with stratigraphic evidence of Weichselian ice sheet fluctuation in order to simulate ice sheet attributes through time along the flowline. The model predicts extensive melting at the base of the ice sheet. This output has been used as an input to a simplified model of hydrogeology along the southern flank of the ice sheet so as to reconstruct patterns of subglacial groundwater flow. The output from the model is also used to estimate patterns of subglacial stress and strain. Results suggest that large scale subglacial groundwater catchment are formed which were quite differentin extent from modern catchment; that fossil subglacial groundwaters should be found at sampling depths; and much fracturing in shallow bedrock in Sweden could be glacially generated.

  11. [DEVELOPMENT OF CELL SHEET ENGINEERING TECHNOLOGY IN ENGINEERING VASCULARIZED TISSUE].

    Science.gov (United States)

    Chen, Jia; Ma, Dongyang; Ren, Liling

    2015-03-01

    To review the development of cell sheet engineering technology in engineering vascularized tissue. The literature about cell sheet engineering technology and engineering vascularized tissue was reviewed, analyzed, and summarized. Although there are many methods to engineer vascularized tissue, cell sheet engineering technology provides a promising potential to develop a vascularized tissue. Recently, cell sheet engineering technology has become a hot topic in engineering vascularized tissue. Co-culturing endothelial cells on a cell sheet, endothelial cells are able to form three-dimensional prevascularized networks and microvascular cavities in the cell sheet, which facilitate the formation of functional vascular networks in the transplanted tissue. Cell sheet engineering technology is a promising strategy to engineer vascularized tissue, which is still being studied to explore more potential.

  12. Simulations of the Scandinavian ice sheet and its subsurface conditions

    Energy Technology Data Exchange (ETDEWEB)

    Boulton, G.S.; Caban, P.; Hulton, N. [Edinburgh Univ. (United Kingdom). Dept of Geology and Geophysics

    1999-12-01

    An ice sheet model has been applied to an approximate flow line through the area of the Fennoscandian ice sheet. The modelled ice sheet fluctuations have been matched with stratigraphic evidence of Weichselian ice sheet fluctuation in order to simulate ice sheet attributes through time along the flowline. The model predicts extensive melting at the base of the ice sheet. This output has been used as an input to a simplified model of hydrogeology along the southern flank of the ice sheet so as to reconstruct patterns of subglacial groundwater flow. The output from the model is also used to estimate patterns of subglacial stress and strain. Results suggest that large scale subglacial groundwater catchment are formed which were quite differentin extent from modern catchment; that fossil subglacial groundwaters should be found at sampling depths; and much fracturing in shallow bedrock in Sweden could be glacially generated.

  13. Relation between current sheets and vortex sheets in stationary incompressible MHD

    Directory of Open Access Journals (Sweden)

    D. H. Nickeler

    2012-03-01

    Full Text Available Magnetohydrodynamic configurations with strong localized current concentrations and vortices play an important role in the dissipation of energy in space and astrophysical plasma. Within this work we investigate the relation between current sheets and vortex sheets in incompressible, stationary equilibria. For this approach it is helpful that the similar mathematical structure of magnetohydrostatics and stationary incompressible hydrodynamics allows us to transform static equilibria into stationary ones. The main control function for such a transformation is the profile of the Alfvén-Mach number MA, which is always constant along magnetic field lines, but can change from one field line to another. In the case of a global constant MA, vortices and electric current concentrations are parallel. More interesting is the nonlinear case, where MA varies perpendicular to the field lines. This is a typical situation at boundary layers like the magnetopause, heliopause, the solar wind flowing around helmet streamers and at the boundary of solar coronal holes. The corresponding current and vortex sheets show in some cases also an alignment, but not in every case. For special density distributions in 2-D, it is possible to have current but no vortex sheets. In 2-D, vortex sheets of field aligned-flows can also exist without strong current sheets, taking the limit of small Alfvén Mach numbers into account. The current sheet can vanish if the Alfvén Mach number is (almost constant and the density gradient is large across some boundary layer. It should be emphasized that the used theory is not only valid for small Alfvén Mach numbers MA << 1, but also for MA ≲ 1. Connection to other theoretical approaches and observations and physical effects in space plasmas are presented. Differences in the various aspects of theoretical investigations of current sheets and vortex

  14. Resin infusion of layered metal/composite hybrid and resulting metal/composite hybrid laminate

    Science.gov (United States)

    Cano, Roberto J. (Inventor); Grimsley, Brian W. (Inventor); Weiser, Erik S. (Inventor); Jensen, Brian J. (Inventor)

    2009-01-01

    A method of fabricating a metal/composite hybrid laminate is provided. One or more layered arrangements are stacked on a solid base to form a layered structure. Each layered arrangement is defined by a fibrous material and a perforated metal sheet. A resin in its liquid state is introduced along a portion of the layered structure while a differential pressure is applied across the laminate structure until the resin permeates the fibrous material of each layered arrangement and fills perforations in each perforated metal sheet. The resin is cured thereby yielding a metal/composite hybrid laminate.

  15. Coupling Hollow Fe3O4-Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material.

    Science.gov (United States)

    Qu, Bin; Zhu, Chunling; Li, Chunyan; Zhang, Xitian; Chen, Yujin

    2016-02-17

    We developed a strategy for coupling hollow Fe3O4-Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4-Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach -30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4-Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

  16. Temperature sheets and aspect sensitive radar echoes

    Directory of Open Access Journals (Sweden)

    H. Luce

    Full Text Available here have been years of discussion and controversy about the existence of very thin and stable temperature sheets and their relationship to the VHF radar aspect sensitivity. It is only recently that very high-resolution in situ temperature observations have brought credence to the reality and ubiquity of these structures in the free atmosphere and to their contribution to radar echo enhancements along the vertical. Indeed, measurements with very high-resolution sensors are still extremely rare and rather difficult to obtain outside of the planetary boundary layer. They have only been carried out up to the lower stratosphere by Service d’A´ eronomie (CNRS, France for about 10 years. The controversy also persisted due to the volume resolution of the (Mesosphere-Stratosphere-Troposphere VHF radars which is coarse with respect to sheet thickness, although widely sufficient for meteorological or mesoscale investigations. The contribution within the range gate of many of these structures, which are advected by the wind, and decay and grow at different instants and could be distorted either by internal gravity waves or turbulence fields, could lead to radar echoes with statistical properties similar to those produced by anisotropic turbulence. Some questions thus remain regarding the manner in which temperature sheets contribute to VHF radar echoes. In particular, the zenithal and azimuthal angular dependence of the echo power may not only be produced by diffuse reflection on stable distorted or corrugated sheets, but also by extra contributions from anisotropic turbulence occurring in the stratified atmosphere. Thus, for several years, efforts have been put forth to improve the radar height resolution in order to better describe thin structures. Frequency interferometric techniques are widely used and have been recently further developed with the implementation of high-resolution data processings. We begin by reviewing briefly some characteristics

  17. In situ emulsion cationic polymerization of isoprene onto the surface of graphite oxide sheets

    Science.gov (United States)

    Pazat, Alice; Beyou, Emmanuel; Barrès, Claire; Bruno, Florence; Janin, Claude

    2017-02-01

    Grafting of polymers onto graphite oxide sheets (GO) has been widely studied in recent years due to the numerous applications of GO-based composites. Herein, polyisoprene (PI) chains were anchored on the surface of GO by in situ cationic polymerization using a "grafting through" approach with allyltrimethoxysilane-modified GO (GO-ATMS). First, the functionalization of GO sheets through the hydrolysis-condensation of allyltrimethoxysilane (ATMS) molecules was qualitatively evidenced by infra-red spectroscopy and X-ray photoelectron spectrometry and a weight content of 4% grafted ATMS was calculated from thermogravimetric analysis. Then, isoprene was in situ polymerized through a one-pot cationic mechanism by using a highly water-dispersible Lewis acid surfactant combined catalyst. For comparison, it was shown that the cationic polymerization of isoprene in presence of un-functionalized GO sheets led to a polyisoprene weight content on the solid filler divided by 3 compared to GO-ATMS. Finally, the compounding of the modified GO/PI composites was performed at a processing temperature of 80 °C with 2 phr and 15 phr loadings and it was shown a decrease of the air permeability coefficient of 27% for the vulcanizates with 15 phr loading.

  18. Co-firing of LNT/Ag Multilayer Sheets Prepared by Aqueous Tape Casting

    Institute of Scientific and Technical Information of China (English)

    Shaochun Li; Qilong Zhang; Hui Yang

    2009-01-01

    Multilayer ceramic sheets composed of Li1.075Nb0.625Ti0.45O3 (LNT) layers and silver metal layers were fabricated by aqueous tape-casting method. LNT green tape was prepared using PVA (polyvinyl alcohol) as binder and ethylene glycol as plasticizer. The influence of the slurry composition on the theological properties of the slurries and the properties of the resultant green tapes were studied. The slurry exhibited a typical shear thinning behavior. The increase in the PVA content increased the tensile strength of the tapes. The slip compositions with 5 wt pct PVA produced green tapes with satisfactory tensile strength. Ethylene glycol additions enhanced the flexibility of the green tapes but also produced a decrease in the tensile strength. Sliver inner-electrode was pasted on LNT green tapes and the sheets were stacked, pressed and sintered at 900℃ for 2 h. SEM (scanning electron microscopy) micrographs showed that the multilayer sheets were fully dense with fairly uniform microstructure and no reaction was observed between LNT and sliver layers.

  19. Sheet-bulk metal forming – forming of functional components from sheet metals

    Directory of Open Access Journals (Sweden)

    Merklein Marion

    2015-01-01

    Full Text Available The paper gives an overview on the application of sheet-bulk metal forming operations in both scientific and industrial environment. Beginning with the need for an innovative forming technology, the definition of this new process class is introduced. The rising challenges of the application of bulk metal forming operations on sheet metals are presented and the demand on a holistic investigation of this topic is motivated. With the help of examples from established production processes, the latest state of technology and the lack on fundamental knowledge is shown. Furthermore, perspectives regarding new research topics within sheet-bulk metal forming are presented. These focus on processing strategies to improve the quality of functional components by the application of process-adapted semi-finished products as well as the local adaption of the tribological system.

  20. Macrocyclic beta-sheet peptides that mimic protein quaternary structure through intermolecular beta-sheet interactions.

    Science.gov (United States)

    Khakshoor, Omid; Demeler, Borries; Nowick, James S

    2007-05-02

    This paper reports the design, synthesis, and characterization of a family of cyclic peptides that mimic protein quaternary structure through beta-sheet interactions. These peptides are 54-membered-ring macrocycles comprising an extended heptapeptide beta-strand, two Hao beta-strand mimics [JACS 2000, 122, 7654] joined by one additional alpha-amino acid, and two delta-linked ornithine beta-turn mimics [JACS 2003, 125, 876]. Peptide 3a, as the representative of these cyclic peptides, contains a heptapeptide sequence (TSFTYTS) adapted from the dimerization interface of protein NuG2 [PDB ID: 1mio]. 1H NMR studies of aqueous solutions of peptide 3a show a partially folded monomer in slow exchange with a strongly folded oligomer. NOE studies clearly show that the peptide self-associates through edge-to-edge beta-sheet dimerization. Pulsed-field gradient (PFG) NMR diffusion coefficient measurements and analytical ultracentrifugation (AUC) studies establish that the oligomer is a tetramer. Collectively, these experiments suggest a model in which cyclic peptide 3a oligomerizes to form a dimer of beta-sheet dimers. In this tetrameric beta-sheet sandwich, the macrocyclic peptide 3a is folded to form a beta-sheet, the beta-sheet is dimerized through edge-to-edge interactions, and this dimer is further dimerized through hydrophobic face-to-face interactions involving the Phe and Tyr groups. Further studies of peptides 3b-3n, which are homologues of peptide 3a with 1-6 variations in the heptapeptide sequence, elucidate the importance of the heptapeptide sequence in the folding and oligomerization of this family of cyclic peptides. Studies of peptides 3b-3g show that aromatic residues across from Hao improve folding of the peptide, while studies of peptides 3h-3n indicate that hydrophobic residues at positions R3 and R5 of the heptapeptide sequence are important in oligomerization.

  1. Oxygen plasma-treated thermoresponsive polymer surfaces for cell sheet engineering.

    Science.gov (United States)

    Shimizu, Kazunori; Fujita, Hideaki; Nagamori, Eiji

    2010-06-01

    Although cell sheet tissue engineering is a potent and promising method for tissue engineering, an increase of mechanical strength of a cell sheet is needed for easy manipulation of it during transplantation or 3D tissue fabrication. Previously, we developed a cell sheet-polymer film complex that had enough mechanical strength that can be manipulated even by tweezers (Fujita et al., 2009. Biotechnol Bioeng 103(2): 370-377). We confirmed the polymer film involving a temperature sensitive polymer and extracellular matrix (ECM) proteins could be removed by lowering temperature after transplantation, and its potential use in regenerative medicine was demonstrated. However, the use of ECM proteins conflicted with high stability in long-term storage and low cost. In the present study, to overcome these drawbacks, we employed the oxygen plasma treatment instead of using the ECM proteins. A cast and dried film of thermoresponsive poly-N-isopropylacrylamide (PNIPAAm) was fabricated and treated with high-intensity oxygen plasma. The cells became possible to adhere to the oxygen plasma-treated PNIPAAm surface, whereas could not to the inherent surface of bulk PNIPAAm without treatment. Characterizations of the treated surface revealed the surface had high stability. The surface roughness, wettability, and composition were changed, depending on the plasma intensity. Interestingly, although bulk PNIPAAm layer had thermoresponsiveness and dissolved below lower critical solution temperature (LCST), it was found that the oxygen plasma-treated PNIPAAm surface lost its thermoresponsiveness and remained insoluble in water below LCST as a thin layer. Skeletal muscle C2C12 cells could be cultured on the oxygen plasma-treated PNIPAAm surface, a skeletal muscle cell sheet with the insoluble thin layer could be released in the medium, and thus the possibility of use of the cell sheet for transplantation was demonstrated.

  2. Tensile properties of bacterial cellulose nanofibers - polyester composites

    Science.gov (United States)

    Abral, H.; Mahardika, M.

    2016-07-01

    The paper shows tensile properties of bacterial cellulose (BC) nanofibers and polyester (PO) matrix composites. Tensile properties including tensile strength (TS), modulus elasticity (ME), and elongation (EL) were observed respectively. BC nanofibers exist in the form of a sheet that was then varied in matrix PO. The BC sheet was mounted by one, three, five and seven pieces respectively in the matrix PO. The tensile strength of the composites was conducted by using the tensile equipment. The results showed that the tensile strength of the composite with a single sheet of BC was lower than that of pure PO. The ST value achieved maximum level in the number of layers of BC three pieces, but then it decreased for the composites reinforced five and seven pieces of BC nanofiber, respectively. Scanning Electron Microscope (SEM) observation exhibits bad interface bonding between BC nanofibers and PO matrix.

  3. Preparation of nanoporous graphene sheets via free radical oxidation of graphene oxide and their application in lithium ion battery

    Science.gov (United States)

    Zhou, Xuejiao; Xu, Liangyou; Ma, Xiaohua

    2017-07-01

    Graphene is an attractive candidate for use as an electrode material in electrochemical energy storage due to its unique structure and excellent properties. Compared with graphene, nanoporous graphene is a superior electrode material, owing to the porous structure of its graphene sheets, which facilitates cross-plane lithium ion transportation and provides more binding sites for the lithium ions during the lithiation/delithiation process. In this work, we demonstrate a simple and efficient strategy for obtaining nanoporous graphene on a large scale. Nanoporous graphene can be generated through the oxidation of graphene oxide by H2O2 under high-power UV irradiation with a subsequent reduction process. The morphology, chemical composition and defects of the as-generated nanoporous graphene were studied. The electrochemical evaluation of the nanoporous graphene sheets showed that it delivered higher specific capacity and better charge/discharge rate capability compared with chemically reduced graphene sheets for use as an anode material in lithium ion batteries.

  4. Palaeo sea-level and ice-sheet databases: problems, strategies and perspectives

    Directory of Open Access Journals (Sweden)

    A. Düsterhus

    2015-06-01

    Full Text Available Sea-level and ice-sheet databases are essential tools for evaluating palaeoclimatic changes. However, database creation poses considerable challenges and problems related to the composition and needs of scientific communities creating raw data, the compiliation of the database, and finally using it. There are also issues with data standardisation and database infrastructure, which should make the database easy to understand and use with different layers of complexity. Other challenges are correctly assigning credit to original authors, and creation of databases that are centralised and maintained in long-term digital archives. Here, we build on the experience of the PALeo constraints on SEA level rise (PALSEA community by outlining strategies for designing a self-consistent and standardised database of changes in sea level and ice sheets, identifying key points that need attention when undertaking the task of database creation.

  5. Spunlaced Cotton and Cotton Blend Cosmetic Pads and Bed Sheets: Study of Fiber Entanglement

    Directory of Open Access Journals (Sweden)

    U. Muenstermann

    2007-11-01

    Full Text Available Nonwoven webs containing five different blends of bleached cotton with Lyocell rayon, bicomponent core/sheath polyester/polyethylene, or cotton comber noil were prepared by either light needlepunching, or light needlepunching followed by spunlacing (hydroentanglement. We optically acquired fiber bundle size measurements to learn about the pre-needling process, the hydroentangling process and the influence of fiber blend composition on fiber entanglement. Fiber entanglement measurements were compared to basis weight uniformity measurements. One of the bed sheet developments utilized a combination of bonding technologies (spunlacing and thermal bonding that used low energy. Results from this work indicate that spunlacing produced high quality cosmetic pads and economical short-life bed sheeting.

  6. Analysis and experiment on deformation of sheet metal by laser shock wave

    Institute of Scientific and Technical Information of China (English)

    YANG Chao-jun; ZHANG Yong-kang; ZHOU Jian-zhong; NI Ming-xiong; DU Jian-jun; HUANG Shu; FENG Ai-xin; ZHANG Lei-hong

    2006-01-01

    The mechanism of laser shock deformation and the reason for the production of the shockwave are introduced.An evaluation formula of the detonation wave pressure in the system of laser,energy transferring-medium and sheet metal is built according to the theory of detonation wave and blasting gas-dynamics.The minimal energy of the laser pulse is evaluated on the basis of the formula of the laser shock pressure and evaluation of dynamic yielding strength.The experiment is also validated.The result shows that the quantity of sheet metal deforming is nonlinearly increased with laser energy,i.e.,pressure of the laser shock wave.Under a laser-induced ultra-high pressure and high strain rate,structural steels and composite materials undergo plastic deformation.

  7. Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

    Science.gov (United States)

    Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

  8. Progress in understanding sheeting joints over the past two centuries

    Science.gov (United States)

    Martel, Stephen J.

    2017-01-01

    Sheeting joints share many geometric, textural, and kinematic features with other joints, but differ in that they are (a) discernibly curved, and (b) open near to and subparallel to the topographic surface. Where sheeting joints are geologically young, the surface-parallel compressive stresses are large, typically several MPa or greater. Sheeting joints typically are best developed beneath domes, ridges, and saddles. They also are reported beneath valleys or bowls. A mechanism that accounts for these associations has been sought for more than a century: the commonly subscribed explanation of erosion of overburden, by itself, is inadequate. Principles of fracture mechanics, together with the mechanical effects of a curved topographic surface experiencing a surface-parallel compression, provide a framework that accounts for the cardinal characteristics of sheeting joints. A compressive stress parallel to a convex topographic surface induces a tension perpendicular to the surface at shallow depths. In some cases, this combination alone can overcome the weight of overburden to open sheeting joints. Plausible distributions of water pressure in sheeting joints would help open and drive sheeting joints beneath valleys, saddles, and bowls. Thermal stresses help sheeting joints develop very near the ground surface. Sheeting joints thus appear to reflect an intricate fracture process primarily involving the shape, slope, and scale of the topography; the regional horizontal stresses; the effect of gravity; and groundwater pressure. Understanding how sheeting joints evolve in three dimensions through time remains an outstanding challenge and would illuminate their effect on landscapes, slope stability, and fluid flow.

  9. Dependence of α-helical and β-sheet amino acid propensities on the overall protein fold type

    Directory of Open Access Journals (Sweden)

    Fujiwara Kazuo

    2012-08-01

    Full Text Available Abstract Background A large number of studies have been carried out to obtain amino acid propensities for α-helices and β-sheets. The obtained propensities for α-helices are consistent with each other, and the pair-wise correlation coefficient is frequently high. On the other hand, the β-sheet propensities obtained by several studies differed significantly, indicating that the context significantly affects β-sheet propensity. Results We calculated amino acid propensities for α-helices and β-sheets for 39 and 24 protein folds, respectively, and addressed whether they correlate with the fold. The propensities were also calculated for exposed and buried sites, respectively. Results showed that α-helix propensities do not differ significantly by fold, but β-sheet propensities are diverse and depend on the fold. The propensities calculated for exposed sites and buried sites are similar for α-helix, but such is not the case for the β-sheet propensities. We also found some fold dependence on amino acid frequency in β-strands. Folds with a high Ser, Thr and Asn content at exposed sites in β-strands tend to have a low Leu, Ile, Glu, Lys and Arg content (correlation coefficient = −0.90 and to have flat β-sheets. At buried sites in β-strands, the content of Tyr, Trp, Gln and Ser correlates negatively with the content of Val, Ile and Leu (correlation coefficient = −0.93. "All-β" proteins tend to have a higher content of Tyr, Trp, Gln and Ser, whereas "α/β" proteins tend to have a higher content of Val, Ile and Leu. Conclusions The α-helix propensities are similar for all folds and for exposed and buried residues. However, β-sheet propensities calculated for exposed residues differ from those for buried residues, indicating that the exposed-residue fraction is one of the major factors governing amino acid composition in β-strands. Furthermore, the correlations we detected suggest that amino acid composition is related to folding

  10. Evidence of meltwater retention within the Greenland ice sheet

    Directory of Open Access Journals (Sweden)

    A. K. Rennermalm

    2013-09-01

    Full Text Available Greenland ice sheet mass losses have increased in recent decades with more than half of these attributed to surface meltwater runoff. However, the magnitudes of englacial storage, firn retention, internal refreezing and other hydrologic processes that delay or reduce true water export to the global ocean remain less understood, partly due to a scarcity of in situ measurements. Here, ice sheet surface meltwater runoff and proglacial river discharge between 2008 and 2010 near Kangerlussuaq, southwestern Greenland were used to establish sub- and englacial meltwater storage for a small ice sheet watershed (36–64 km2. This watershed lacks significant potential meltwater storage in firn, surface lakes on the ice sheet and in the proglacial area, and receives limited proglacial precipitation. Thus, ice sheet surface runoff not accounted for by river discharge can reasonably be attributed to retention in sub- and englacial storage. Evidence for meltwater storage within the ice sheet includes (1 characteristic dampened daily river discharge amplitudes relative to ice sheet runoff; (2 three cold-season river discharge anomalies at times with limited ice sheet surface melt, demonstrating that meltwater may be retained up to 1–6 months; (3 annual ice sheet watershed runoff is not balanced by river discharge, and while near water budget closure is possible as much as 54% of melting season ice sheet runoff may not escape to downstream rivers; (4 even the large meltwater retention estimate (54% is equivalent to less than 1% of the ice sheet volume, which suggests that storage in en- and subglacial cavities and till is plausible. While this study is the first to provide evidence for meltwater retention and delayed release within the Greenland ice sheet, more information is needed to establish how widespread this is along the Greenland ice sheet perimeter.

  11. Mineral and chemical variations within an ash-flow sheet from Aso caldera, Southwestern Japan

    Science.gov (United States)

    Lipman, P.W.

    1967-01-01

    Although products of individual volcanic eruptions, especially voluminous ash-flow eruptions, have been considered among the best available samples of natural magmas, detailed petrographic and chemical study indicates that bulk compositions of unaltered Pleistocene ash-flow tuffs from Aso caldera, Japan, deviate significantly from original magmatic compositions. The last major ash-flow sheet from Aso caldera is as much as 150 meters thick and shows a general vertical compositional change from phenocryst-poor rhyodacite upward into phenocryst-rich trachyandesite; this change apparently reflects in inverse order a compositionally zoned magma chamber in which more silicic magma overlay more mafic magma. Details of these magmatic variations were obscured, however, by: (1) mixing of compositionally distinct batches of magma during upwelling in the vent, as indicated by layering and other heterogeneities within single pumice lumps; (2) mixing of particulate fragments-pumice lumps, ash, and phenocrysts-of varied compositions during emplacement, with the result that separate pumice lenses from a single small outcrop may have a compositional range nearly as great as the bulk-rook variation of the entire sheet; (3) density sorting of phenocrysts and ash during eruption and emplacement, resulting in systematic modal variations with distance from the caldera; (4) addition of xenocrysts, resulting in significant contamination and modification of proportions of crystals in the tuffs; and (5) ground-water leaching of glassy fractions during hydration after cooling. Similar complexities characterize ash-flow tuffs under study in southwestern Nevada and in the San Juan Mountains, Colorado, and probably are widespread in other ash-flow fields as well. Caution and careful planning are required in study of the magmatic chemistry and phenocryst mineralogy of these rocks. ?? 1967 Springer-Verlag.

  12. Electrode material comprising graphene-composite materials in a graphite network

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Harold H.; Lee, Jung K.

    2017-08-08

    A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

  13. Electrode material comprising graphene-composite materials in a graphite network

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Harold H.; Lee, Jung K.

    2014-07-15

    A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

  14. Highly conductive, multi-layer composite precursor composition to fuel cell flow field plate or bipolar plate

    Science.gov (United States)

    Jang, Bor Z.; Zhamu, Aruna; Guo, Jiusheng

    2011-02-15

    This invention provides a moldable, multiple-layer composite composition, which is a precursor to an electrically conductive composite flow field plate or bipolar plate. In one preferred embodiment, the composition comprises a plurality of conductive sheets and a plurality of mixture layers of a curable resin and conductive fillers, wherein (A) each conductive sheet is attached to at least one resin-filler mixture layer; (B) at least one of the conductive sheets comprises flexible graphite; and (C) at least one resin-filler mixture layer comprises a thermosetting resin and conductive fillers with the fillers being present in a sufficient quantity to render the resulting flow field plate or bipolar plate electrically conductive with a conductivity no less than 100 S/cm and thickness-direction areal conductivity no less than 200 S/cm.sup.2.

  15. Alkylated graphene nanosheet composites with polyaniline nanofibers.

    Science.gov (United States)

    Grinou, Ali; Yun, Young Soo; Cho, Se Youn; Jin, Hyoung-Joon

    2011-07-01

    We demonstrate a simple method to prepare alkylated graphene/polyaniline composites (a-GR/PANI) using solution mixing of exfoliated alkyl Iodododecane treated graphene oxide sheets with polyaniline nanofiber; polyaniline nanofibers (PANI) prepared by using rapid mixing polymerization significantly improve the processibility of polyaniline and its performance in many conventional applications. Also, polyaniline nanofibers exhibit excellent water dispersibility due to their uniform nanofiber morphology. Morphological study using SEM and TEM analysis showed that the fibrous PANI in the composites a-GR/PANI mainly adsorbed onto the surface or intercalated between the graphene sheets, due especially to the good interfacial interaction between the alkylated gaphene and the polyaniline nanofibers. The existence of polyaniline nanofibers on the surface of the garphene and the alkylated graphene sheets was confirmed by using FT-IR, FT-Raman and X-ray diffraction analysis. Due to the good interfacial interaction between the alkylated graphene and the polyanilines nanofibers, the composite (a-GR/PANI) exhibited excellent dispersion stability in DMF compared to the same composite (GR/PANI) without alkylation. The electrical conductivity of the (GR/PANI) composite was 9% higher than that of pure PANI and the same weight percent for the composite after alkylation was 13% higher than that of pure PANI nanofibers.

  16. Deglaciation of the Eurasian ice sheet complex

    Science.gov (United States)

    Patton, Henry; Hubbard, Alun; Andreassen, Karin; Auriac, Amandine; Whitehouse, Pippa L.; Stroeven, Arjen P.; Shackleton, Calvin; Winsborrow, Monica; Heyman, Jakob; Hall, Adrian M.

    2017-08-01

    The Eurasian ice sheet complex (EISC) was the third largest ice mass during the Last Glacial Maximum with a span of over 4500 km and responsible for around 20 m of eustatic sea-level lowering. Whilst recent terrestrial and marine empirical insights have improved understanding of the chronology, pattern and rates of retreat of this vast ice sheet, a concerted attempt to model the deglaciation of the EISC honouring these new constraints is conspicuously lacking. Here, we apply a first-order, thermomechanical ice sheet model, validated against a diverse suite of empirical data, to investigate the retreat of the EISC after 23 ka BP, directly extending the work of Patton et al. (2016) who modelled the build-up to its maximum extent. Retreat of the ice sheet complex was highly asynchronous, reflecting contrasting regional sensitivities to climate forcing, oceanic influence, and internal dynamics. Most rapid retreat was experienced across the Barents Sea sector after 17.8 ka BP when this marine-based ice sheet disintegrated at a rate of ∼670 gigatonnes per year (Gt a-1) through enhanced calving and interior dynamic thinning, driven by oceanic/atmospheric warming and exacerbated by eustatic sea-level rise. From 14.9 to 12.9 ka BP the EISC lost on average 750 Gt a-1, peaking at rates >3000 Gt a-1, roughly equally partitioned between surface melt and dynamic losses, and potentially contributing up to 2.5 m to global sea-level rise during Meltwater Pulse 1A. Independent glacio-isostatic modelling constrained by an extensive inventory of relative sea-level change corroborates our ice sheet loading history of the Barents Sea sector. Subglacial conditions were predominately temperate during deglaciation, with over 6000 subglacial lakes predicted along with an extensive subglacial drainage network. Moreover, the maximum EISC and its isostatic footprint had a profound impact on the proglacial hydrological network, forming the Fleuve Manche mega-catchment which had an area of

  17. A new uranyl phosphate sheet in the crystal structure of furongite

    Energy Technology Data Exchange (ETDEWEB)

    Dal Bo, Fabrice; Hatert, Frederic [Liege Univ. (Belgium). Lab. de Mineralogie; Philippo, Simon [Musee National d' Historie Naturelle, Luxembourg (Luxembourg). Section Mineralogie

    2017-06-15

    The crystal structure of furongite, Al{sub 4}[(UO{sub 2}){sub 4}(PO{sub 4}){sub 6}](OH){sub 2}(H{sub 2}O){sub 19.5}, from the Kobokobo pegmatite, Kivu, Democratic Republic of Congo, was solved for the first time. Furongite is triclinic, the space group P anti 1, Z=2, a = 12.1685(8), b = 14.1579(6), c = 17.7884(6) Aa, α = 79.822(3), β = 77.637(4), γ = 67.293(2) , and V = 2746.2(2)Aa{sup 3}. The crystal structure was refined from single crystal X-ray diffraction data to R{sub 1} = 0.0733 for 7716 unique observed reflections, and to wR{sub 2} = 0.2081 for all 12,538 unique reflections. The structure of furongite contains infinite uranyl phosphate sheets of composition [(UO{sub 2}){sub 4}(PO{sub 4}){sub 6}]{sup 10-} which are parallel to (1 0 1). The sheets are constituted by UrO{sub 5} pentagonal bipyramids and PO{sub 4} tetrahedra which share edges and vertices, and adjacent sheets are linked by a dense network of hydrogen bonds. Running through the sheets and connected mainly to the free apical oxygen atom of PO4 tetrahedra are Al octahedra connected together to form remarkable Al{sub 2}O{sub 5}(OH)(H{sub 2}O){sub 5} and Al{sub 4}O{sub 8}(OH){sub 2}(H{sub 2}O){sub 10} clusters. These Al clusters are only bonded to one sheet, and do not connect two adjacent sheets together. The topology of the uranyl phosphate sheets is related to the uranophane anion topology, and can be described as a new geometrical isomer of the uranophane group. Furongite is the first uranyl phosphate reported in nature with a U:P ratio of 2:3.

  18. Vibration damping characteristics of laminated steel sheet

    Science.gov (United States)

    Chen, Y. S.; Hsu, T. J.; Chen, S. I.

    1991-03-01

    The use of laminated steel sheets as vibration damping materials was studied. The laminate consisted of a viscoelastic layer which was sandwiched between two steel sheets. The study sought to identify parameters affecting the damping efficiency of the laminate. Two viscoelastic materials, a copolymer based on ethylene and acrylic acid (PEAA) and polyvinyl butyral (PVB), were used. A frequency analyzer was used to measure the loss factor of the laminates. A theoretical analysis of damping efficiency based on a model described by Ungar[2] was also carried out. The results showed that the loss factor of the PEAA-based laminates increased monotonically with increasing thickness of the viscoelastic layer and leveled off at 25.9 pct of total thickness. Ungar’s theory predicted a higher loss factor than the experimental data. This might have resulted from interfacial adhesive bonding, a nonuniform viscoelastic layer thickness, and the extrapolation of the rheological data from low to high frequencies. The loss factor of the laminate increased with increasing temperature, reached a maximum value, and then decreased. An optimum temperature for maximum damping was found for each laminate configuration. The PEAA-based laminates possessed higher damping efficiency than the PVB-based laminates at room temperature. The symmetric laminate (with the same steel sheet thickness) possessed a better damping efficiency than asymmetric laminates. The maximum damping peak of the laminates using a polymer blend, when compared to the laminates using unblended resin, exhibited a lower loss factor value, became broader, and occurred at a temperature between the T g’s of the individual components of the polymer blend.

  19. Analysis of groundwater flow beneath ice sheets

    Energy Technology Data Exchange (ETDEWEB)

    Boulton, G. S.; Zatsepin, S.; Maillot, B. [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics

    2001-03-01

    The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix.

  20. Successful transplantation of in vitro expanded human corneal endothelial precursors to corneal endothelial surface using a nanocomposite sheet

    Directory of Open Access Journals (Sweden)

    Parikumar P

    2011-01-01

    Full Text Available Background: Though the transplantation of in vitro expanded human corneal endothelial precursors in animal models of endothelial damage by injecting into the anterior chamber has been reported, the practical difficulties of accomplishing such procedure in human patients have been a hurdle to clinical translation. Here we report the successful transplantation of in vitro expanded human corneal precursor cells to an animal eye using a transparent Nano-composite sheet and their engraftment.Materials and Methods: Human Corneal endothelial cells (HCEC were isolated from human cadaver eyes with informed consent and expanded in the lab using a sphere forming assay in a novel Thermoreversible Gelation Polymer (TGP for 26 days. HCEC obtained by sphere forming assay were seeded in a novel Nano-composite sheet, which was made of PNIPA-NC gels by in-situ, free-radical polymerization of NIPA monomer in the presence of exfoliated clay (synthetic hectorite “Laponite XLG” uniformly dispersed in aqueous media. After a further seven days in vitro culture of HCEC in the Nano-composite sheet, cells were harvested and transplanted on cadaver-bovine eyes (n=3. The cells were injected between the corneal endothelial layer and the Nano-composite sheet that had been placed prior to the injection in close proximity to the endothelial layer. After three hours, the transplanted Nano-composite sheets were removed from the bovine eyes and subjected to microscopic examination. The corneas were subjected to Histo-pathological studies along with controls. Results: HCEC formed sphere like colonies in TGP which expressed relevant markers as confirmed by RT-PCR. Microscopic studies of the Nanosheets and histopathological studies of the cornea of the Bull’s eye revealed that the HCEC got engrafted to the corneal endothelial layer of the bovine eyes with no remnant cells in the Nanosheet. Conclusion: Transplantation of in vitro expanded donor human corneal endothelial cells

  1. Accounting balance sheet as a system

    Directory of Open Access Journals (Sweden)

    Lukin Vladimir

    2016-04-01

    Full Text Available The article actualizes the need to study the systematic approach and accountants’ systematical thinking based on the analysis of the systems theory basic provisions, the applicability of the system properties to the "balance sheet" category and to explore the basic tenets of the existing schools of accounting. It is proved that the accounting is a complex socio-technical system; justified that the study of accounting from the perspective of a systematic approach will enable a better understanding of its structure, principles of functioning and the role of an accountant in its practical implementation.

  2. BALANCE-SHEET vs. ARBITRAGE CDOs

    Directory of Open Access Journals (Sweden)

    SILVIU EDUARD DINCA

    2016-02-01

    Full Text Available During the past few years, in the recent post-crisis aftermath, global asset managers are constantly searching new ways to optimize their investment portfolios while financial and banking institutions around the world are exploring new alternatives to better secure their financing and refinancing demands altogether with the enhancement of their risk management capabilities. We will exhibit herewith a comparison between the balance-sheet and arbitrage CDO securitizations as financial markets-based funding, investment and risks mitigation techniques, highlighting certain key structuring and implementation specifics on each of them.

  3. The stretch zone of automotive steel sheets

    Indian Academy of Sciences (India)

    Ľ Ambriško; L Pešek

    2014-04-01

    The paper deals with an experimental determination of the stretch zone dimensions in the notch tip in thin steel sheets. The stretch zone dimensions depend on steel grade, on the rolling direction as well as on the loading rate. Stretch zones were observed and measured on three steel grades. Fracture area and stretch zones were analysed by SEM. Stable crack growth was monitored by videoextensometry techniques on CT (Compact Tension) specimens. Specimens were loaded under two loading rates by eccentric tension, whereby the deformation in the notch surrounding area was recorded using a non-contact measurement–videoextensometry technique. Linear relation between the stretch zone dimensions was determined.

  4. Growth of Greenland ice sheet - Measurement

    Science.gov (United States)

    Zwally, H. Jay; Bindschadler, Robert A.; Marsh, James G.; Brenner, Anita C.; Major, Judy A.

    1989-01-01

    Measurements of ice-sheet elevation change by satellite altimetry show that the Greenland surface elevation south of 72 deg north latitude is increasing. The vertical velocity of the surface is 0.20 + or - 0.06 meters/year from measured changes in surface elevations at 5906 intersections between Geosat paths in 1985 and Seasat in 1978, and 0.28 + or - 0.02 meters/year from 256,694 intersections of Geosat paths during a 548-day period of 1985 to 1986.

  5. SOME ASPECTS REGARDING BALANCE SHEET ANALYSIS

    Directory of Open Access Journals (Sweden)

    ILIE RĂSCOLEAN

    2014-10-01

    Full Text Available This paper presents some aspects of the analysis based on the balance sheet at an economic entity. Attempting to use economic analysis as a support tool in the decision. The case study is performed on the financial accounts of a company, analyzing the structure of the assets using the following rates: the rate of intangible assets; rate of tangible assets; rate financial assets; rate stocks; rate receivables and cash and cash equivalents rate. Liability structure is analyzed using the following rates: the rate of financial stability; global financial autonomy rate; overall borrowing rate; term borrowing rate.

  6. Advanced sheet steels for automotive applications

    Science.gov (United States)

    Fekete, James R.; Strugala, Donald C.; Yao, Zhicong

    1992-01-01

    Vacuum degassing has recently been used by sheet steel producers to improve their products' ductility and strength. Carbon contents can be reduced by an order of magnitude to less than 0.0030 wt.%. Through careful alloying and processing, a range of new steel products has been developed for the automotive industry. These products include interstitial-free, deep-drawing-quality steels; formable, high-strength, interstitial-free steels; and bake-hardenable steels. This article summarizes the chemistry and processing needed to produce these products.

  7. SunShot Initiative Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    DOE Solar Energy Technologies Office

    2015-04-01

    The U.S. Department of Energy (DOE) SunShot Initiative is a collaborative national effort launched in 2011 that aggressively drives innovation to make solar energy fully cost competitive with traditional energy sources before the end of the decade. The SunShot fact sheet outlines goals and successes of the program as it works with private companies, universities, non-profit organizations, state and local governments, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour, without incentives, by the year 2020.

  8. Effect of Mantle Rheology on Viscous Heating induced during Ice Sheet Cycles

    Science.gov (United States)

    Huang, Pingping; Wu, Patrick; van der Wal, Wouter

    2017-04-01

    Hanyk et al. (2005) studied the viscous shear heating in the mantle induced by the surface loading and unloading of a parabolic-shaped Laurentide-size ice sheet. They found that for linear rheology, viscous heating is mainly concentrated below the ice sheet. The depth extent of the heating in the mantle is determined by the viscosity distribution. Also, the magnitude of viscous heating is significantly affected by the rate of ice thickness change. However, only one ice sheet has been considered in their work and the interactions between ice sheets and ocean loading have been neglected. Furthermore, only linear rheology has been considered, although they suggested that non-Newtonian rheology may have a stronger effect. Here we follow Hanyk et al. (2005) and computed the viscous dissipation for viscoelastic models using the finite element methodology of Wu (2004) and van der Wal et al. (2010). However, the global ICE6G model (Peltier et al. 2015) with realistic oceans is used here to provide the surface loading. In addition, viscous heating in non-linear rheology, composite rheology, in addition to linear rheology with uniform or VM5a profile are computed and compared. Our results for linear rheology mainly confirm the findings of Hanyk et al. (2005). For both non-linear and composite rheologies, viscous heating is also mainly distributed near and under the ice sheets, but, more concentrated; depending on the horizontal dimension of the ice sheet, it can extend into the lower mantle, but for some of the time, not as deep as that for linear rheology. For composite rheology, the viscous heating is dominated by the effect of non-linear relation between the stress and the strain. The ice history controls the time when the local maximum in viscous heating appears. However, the magnitude of the viscous heating is affected by mantle rheology as well as the ice loading. Due to viscosity stratification, the shape of the region with high viscous heating in model VM5a is a

  9. Thin current sheets in the deep geomagnetic tail

    Energy Technology Data Exchange (ETDEWEB)

    Pulkkinen, T.I. (Finnish Meteorological Institute, Helsinki (Finland)); Baker, D.N.; Owen, C.J. (NASA/Goddard Space Flight Center, Greenbelt, MD (United States)); Gosling, J.T. (Los Alamos National Lab., NM (United States)); Murphy, N. (Jet Propulsion Lab., Pasadena, CA (United States))

    1993-11-19

    The ISEE-3 magnetic field and plasma electron data from Jan-March 1983 have been searched to study thin current sheets in the deep tail region. 33 events were selected where the spacecraft crossed through the current sheet from lobe to lobe within 15 minutes. The average thickness of the observed current sheets was 2.45R[sub E], and in 24 cases the current sheet was thinner than 3.0R[sub E]; 6 very thin current sheets (thickness [lambda] < 0.5R[sub E]) were found. The electron data show that the very thin current sheets are associated with considerable temperature anisotropy. On average, the electron gradient current was [approximately]17% of the total current, whereas the current arising from the electron temperature anisotropy varied between 8-45% of the total current determined from the lobe field magnitude. 21 refs., 5 figs.

  10. Automatically extracting sheet-metal features from solid model

    Institute of Scientific and Technical Information of China (English)

    刘志坚; 李建军; 王义林; 李材元; 肖祥芷

    2004-01-01

    With the development of modern industry,sheet-metal parts in mass production have been widely applied in mechanical,communication,electronics,and light industries in recent decades; but the advances in sheet-metal part design and manufacturing remain too slow compared with the increasing importance of sheet-metal parts in modern industry. This paper proposes a method for automatically extracting features from an arbitrary solid model of sheet-metal parts; whose characteristics are used for classification and graph-based representation of the sheet-metal features to extract the features embodied in a sheet-metal part. The extracting feature process can be divided for valid checking of the model geometry,feature matching,and feature relationship. Since the extracted features include abundant geometry and engineering information,they will be effective for downstream application such as feature rebuilding and stamping process planning.

  11. Uniform Decoration of Reduced Graphene Oxide Sheets with Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Huanping Yang

    2012-01-01

    Full Text Available A simple method employing ionic liquid functionalization is developed to achieve the uniform decoration of reduced graphene oxide sheets with gold nanoparticles. The synthesis of ionic liquid modified graphene oxide is accomplished by covalently binding 1-(3-Aminopropyl imidazole with GO sheets. The formation mechanism of Au nanoparticles on RGO sheets is proposed to load AuCl4- onto the surface of GO sheets through anion exchange; then reduce AuCl4- to Au NPs and at the same time reduce GO sheets to RGO sheets via a one-step process. The presence of Au NPs is well identified by SEM, TEM, and XPS. As a concept, the RGO-supported Au NPs is applied to surface-enhanced Raman spectroscopy.

  12. Electromagnetic radiation from a kicked sheet of charge

    Science.gov (United States)

    Peters, P. C.

    1986-03-01

    The plane-wave electromagnetic fields for a kicked sheet of charge are found and then compared with the fields obtained by superimposing the radiation fields of the individual charges in the plane. Unlike the case of the oscillating sheet of charge discussed in The Feynman Lectures on Physics, Vol. I [R. P. Feynman et al. (Addison-Wesley, Reading, MA, 1963)], the plane-wave fields of the kicked sheet differ from the fields obtained by superposition of the individual radiation fields. The resolution of this problem requires consideration of relativistic effects even though the velocity of the sheet after the kick may be as small as desired. The relation between the solution for the kicked sheet and solution for the oscillating sheet is discussed, and it is shown how the two solutions are consistent if all contributions to the fields are taken into account.

  13. West antarctic ice sheet collapse: Chimera or clear danger

    Energy Technology Data Exchange (ETDEWEB)

    Alley, R.B. (Pennsylvania State Univ., University Park, PA (United States)); MacAyeal, D.R. (Univ. of Chicago, IL (United States))

    1993-01-01

    The specter of a west antarctic collapse has been with us for 25 years. Recently, certain official assessments concerned primarily with the future response to projected global warming have concluded that Antarctica will not cause much sea-level rise within the planning horizon of a century or so. At the same time startling new results on ice sheet (in)stability have been emerging, pointing to less stability then previously believed. Some recent results are reviewed briefly: Heinrich layers in the North Atlantic show basally lubricated surges of the Laurentide ice sheet; the west antarctic ice sheet collapsed recently; the modern west antarctic ice sheet is changing rapidly locally; the bed of ice stream B is exceptionally well lubricated by water and water-saturated soft sediments; the modern ice sheet is thinning slowly on average; a model west antarctic ice sheet undergoes rapid collapses long after forcing and probably related to penetration of warmth to the bed. 23 refs.

  14. A twin-mirrored galvanometer laser light sheet generator

    Science.gov (United States)

    Rhodes, David B.; Franke, John M.; Jones, Stephen B.; Leighty, Bradley D.

    1988-01-01

    A galvanometer mirror-based laser light sheet system has been developed for use in the Basic Aerodynamics Research Tunnel at NASA Langley. This system generates and positions single or multiple light sheets over aeronautical research models being tested in the low speed tunnel. This report describes a twin mirrored galvanometer laser light sheet generator and shows typical light sheet arrangements in use. With this system, illumination of smoke entrained in the flow over a delta wing model reveals the vortical flow produced by the separation of the flow at the leading edge of the model. The light sheet system has proven to be very adaptable and easy to use in sizing and positioning light sheets in wind tunnel applications.

  15. Automatically extracting sheet-metal features from solid model

    Institute of Scientific and Technical Information of China (English)

    刘志坚; 李建军; 王义林; 李材元; 肖祥芷

    2004-01-01

    With the development of modern industry, sheet-metal parts in mass production have been widely applied in mechanical, communication, electronics, and light industries in recent decades; but the advances in sheet-metal part design and manufacturing remain too slow compared with the increasing importance of sheet-metal parts in modern industry. This paper proposes a method for automatically extracting features from an arbitrary solid model of sheet-metal parts; whose characteristics are used for classification and graph-based representation of the sheet-metal features to extract the features embodied in a sheet-metal part. The extracting feature process can be divided for valid checking of the model geometry, feature matching, and feature relationship. Since the extracted features include abundant geometry and engineering information, they will be effective for downstream application such as feature rebuilding and stamping process planning.

  16. Single Point Incremental Forming using a Dummy Sheet

    DEFF Research Database (Denmark)

    Skjødt, Martin; Silva, Beatriz; Bay, Niels

    2007-01-01

    A new version of single point incremental forming (SPIF) is presented. This version includes a dummy sheet on top of the work piece, thus forming two sheets instead of one. The dummy sheet, which is in contact with the rotating tool pin, is discarded after forming. The new set-up influences...... the process and furthermore offers a number of new possibilities for solving some of the problems appearing in SPIF. Investigations of the influence of dummy sheet on: formability, wear, surface quality and bulging of planar sides is done by forming to test shapes: a hyperboloid and a truncated pyramid....... The possible influence of friction between the two sheets is furthermore investigated. The results show that the use of a dummy sheet reduces wear of the work piece to almost zero, but also causes a decrease in formability. Bulging of the planar sides of the pyramid is reduced and surface roughness...

  17. The Formablity of AZ31B Magnesium Alloy Sheet

    Institute of Scientific and Technical Information of China (English)

    WANG Lingyun; LU Zhiwen; ZHAO Yazhong; QIU Xiaogang

    2006-01-01

    The forming limit diagrams(FLD)of AZ31B magnesium alloy sheet were tested by means of the electro etching grid method based on the forming experiment of magnesium alloy sheet carried out with a BCS-30D sheet forming testing machine and the strain testing analysis made with an advanced ASAME automatic strain measuring system. Experiments show that, at room temperature, the mechanical properties and deep drawing performance of AZ31B cold-rolled magnesium alloy sheet were so poor that it failed to test the forming limit diagrams without an ideal forming and processing capacity, while the hot-rolled magnesium alloy sheet was of a little better plasticity and forming performance after testing its forming limit diagrams. It can be concluded that the testing of the forming limit curves (FLC)offers the theoretical foundation for the drawing of the deep drawing and forming process of magnesium alloy sheet.

  18. Friction Model for FEM Simulation of Sheet Metal Forming Operations

    Science.gov (United States)

    Keum, Y. T.; Wagoner, R. H.; Lee, J. K.

    2004-06-01

    In order to find the effect of frictional characteristics, lubricant viscosity, tool geometry, and forming speed on the sheet metal forming, a friction tester was designed and manufactured. Friction tests were performed using drawing oils, various tool radii and forming speeds for aluminum alloy sheets, galvanized steels sheets and cold rolled steel sheets. From the experimental observation, the mathematical friction model considering lubricant viscosity, sheet surface roughness and hardness, punch corner radii, and punch speed is developed. By comparing the punch load found by FEM using the proposed friction model with that of experimental measurement when the steel sheets are formed in 2-D geometry in dry and lubricating conditions, the validity and accuracy of the mathematical friction model are demonstrated.

  19. History of the Greenland Ice Sheet: paleoclimatic insights

    DEFF Research Database (Denmark)

    Alley, Richard B.; Andrews, John Thomas; Brigham-Grette, Julia;

    2010-01-01

    -sheet changes. In contrast, there are no documented major ice-sheet changes that occurred independent of temperature changes. Moreover, snowfall has increased when the climate warmed, but the ice sheet lost mass nonetheless; increased accumulation in the ice sheet's center has not been sufficient to counteract......Paleoclimatic records show that the Greenland Ice Sheet consistently has lost mass in response to warming, and grown in response to cooling. Such changes have occurred even at times of slow or zero sea-level change, so changing sea level cannot have been the cause of at least some of the ice...... increased melting and flow near the edges. Most documented forcings and ice-sheet responses spanned periods of several thousand years, but limited data also show rapid response to rapid forcings. In particular, regions near the ice margin have responded within decades. However, major changes of central...

  20. History of the Greenland Ice Sheet: paleoclimatic insights

    DEFF Research Database (Denmark)

    Alley, Richard B.; Andrews, John Thomas; Brigham-Grette, Julia

    2010-01-01

    increased melting and flow near the edges. Most documented forcings and ice-sheet responses spanned periods of several thousand years, but limited data also show rapid response to rapid forcings. In particular, regions near the ice margin have responded within decades. However, major changes of central......Paleoclimatic records show that the Greenland Ice Sheet consistently has lost mass in response to warming, and grown in response to cooling. Such changes have occurred even at times of slow or zero sea-level change, so changing sea level cannot have been the cause of at least some of the ice......-sheet changes. In contrast, there are no documented major ice-sheet changes that occurred independent of temperature changes. Moreover, snowfall has increased when the climate warmed, but the ice sheet lost mass nonetheless; increased accumulation in the ice sheet's center has not been sufficient to counteract...

  1. Potential Climatic Effects on the Greenland Ice Sheet

    Science.gov (United States)

    Bindschadler, R. A.

    1984-01-01

    The Greenland Ice Sheet covers an area of 1,720,000 sq. km and contains approximately 2,600,000 cu km of ice. Most of the ice sheet receives an excess of snow accumulation over the amount of ice lost to wind, meltwater run-off or other ablative processes. The majority of mass loss occurs at the margin of the ice sheet as either surface melt, which flows into the sea or calving of icebergs from the tongues of outlet glaciers. Many estimates of these processes were published. An average of five published estimates is summarized. If these estimates are correct, then the Greenland Ice Sheet is in approximate equilibrium and contributes 490 cu km/a of fresh water to the North Atlantic and Arctic Oceans. Climate effects, ice sheet flow, and application of remote sensing to tracking of the ice sheet are discussed.

  2. Thickness control in a new flexible hybrid incremental sheet forming process

    OpenAIRE

    Zhang, H.; LU, B; Chen,J.; Feng,S.; Li, Z; Long, H.

    2017-01-01

    Incremental sheet forming is a cost-effective process for rapid manufacturing of sheet metal products. However, incremental sheet forming also has some limitations such as severe sheet thinning and long processing time. These limitations hamper the forming part quality and production efficiency, thus restricting the incremental sheet forming application in industrial practice. To overcome the problem of sheet thinning, a variety of processes, such as multi-step incremental sheet forming, have...

  3. Epilepsy: General Information. Fact Sheet Number 6 = La Epilepsia: Informacion General. Fact Sheet Number 20.

    Science.gov (United States)

    Interstate Research Associates, McLean, VA.

    This fact sheet on epilepsy is offered in both English and Spanish. It provides a definition, information on incidence, typical characteristics, and educational implications. It notes that epilepsy is classified as "other health impaired" under the Individuals with Disabilities Education Act and that students with epilepsy are eligible for special…

  4. Autism: General Information. Fact Sheet Number 1 = Autismo: Informacion General. Fact Sheet Number 22.

    Science.gov (United States)

    Interstate Research Associates, McLean, VA.

    This fact sheet on autism is offered in both English and Spanish, and is the same in both languages although numbered differently. It provides a definition, information on incidence, typical characteristics, and educational implications. It notes that autism is listed as a separate category under the Individuals with Disabilities Education Act.…

  5. Ice sheet model dependency of the simulated Greenland Ice Sheet in the mid-Pliocene

    NARCIS (Netherlands)

    Koenig, S. J.; Dolan, A. M.; De Boer, B.; Stone, E. J.; Hill, D. J.; Deconto, R. M.; Abe-Ouchi, A.; Lunt, D. J.; Pollard, D.; Quiquet, A.; Saito, F.; Savage, J.; Van De Wal, R.

    2015-01-01

    The understanding of the nature and behavior of ice sheets in past warm periods is important for constraining the potential impacts of future climate change. The Pliocene warm period (between 3.264 and 3.025 Ma) saw global temperatures similar to those projected for future climates; nevertheless, Pl

  6. Autism: General Information. Fact Sheet Number 1 = Autismo: Informacion General. Fact Sheet Number 22.

    Science.gov (United States)

    Interstate Research Associates, McLean, VA.

    This fact sheet on autism is offered in both English and Spanish, and is the same in both languages although numbered differently. It provides a definition, information on incidence, typical characteristics, and educational implications. It notes that autism is listed as a separate category under the Individuals with Disabilities Education Act.…

  7. Epilepsy: General Information. Fact Sheet Number 6 = La Epilepsia: Informacion General. Fact Sheet Number 20.

    Science.gov (United States)

    Interstate Research Associates, McLean, VA.

    This fact sheet on epilepsy is offered in both English and Spanish. It provides a definition, information on incidence, typical characteristics, and educational implications. It notes that epilepsy is classified as "other health impaired" under the Individuals with Disabilities Education Act and that students with epilepsy are eligible for special…

  8. Avidin-biotin-based approach to forming heterotypic cell clusters and cell sheets on a gas-permeable membrane

    Energy Technology Data Exchange (ETDEWEB)

    Hamon, M; Ozawa, T; Montagne, K; Kojima, N; Ishii, R; Sakai, Y [Institute of Industrial Science (IIS), University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Yamaguchi, S; Nagamune, T [Department of Bioengineering, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ushida, T, E-mail: mzh0026@auburn.edu [Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2011-09-15

    Implantation of sheet-like liver tissues is a promising method in hepatocyte-based therapies, because angiogenesis is expected to occur upon implantation from the surrounding tissues. In this context, we introduce here a new methodology for the formation of a functional thick hepatic tissue usable for cell sheet technology. First, we report the formation of composite tissue elements in suspension culture. Composite elements were composed of human hepatoma Hep G2 cells and mouse NIH/3T3 fibroblasts which are important modulators for thick-tissue formation. To overcome the very low attachment and organization capability between different cells in suspension, we synthesized a new cell-to-cell binding molecule based on the avidin-biotin binding system that we previously applied to attach hepatocytes on artificial substrata. This newly synthesized biotin-conjugated biocompatible anchoring molecule was inserted in the plasma membrane of both cell types. NIH/3T3 cells were further conjugated with avidin and incubated with biotin-presenting Hep G2 cells to form highly composite tissue elements. Then, we seeded those elements on highly gas-permeable membranes at their closest packing density to induce the formation of a thick, composite, functional hepatic tissue without any perfusion. This methodology could open a new way to engineer implantable thick liver tissue sheets where different cell types are spatially organized and well supplied with oxygen.

  9. Novel pyrolyzed polyaniline-grafted silicon nanoparticles encapsulated in graphene sheets as Li-ion battery anodes.

    Science.gov (United States)

    Li, Zhe-Fei; Zhang, Hangyu; Liu, Qi; Liu, Yadong; Stanciu, Lia; Xie, Jian

    2014-04-23

    A simple method to fabricate graphene-encapsulated pyrolyzed polyaniline-grafted Si nanoparticles has been developed. Instead of using Si nanoparticles with a native oxide layer, HF-treated Si nanoparticles were employed in this work. The uniqueness of this method is that, first, a PANI layer over the Si nanoparticles was formed via the surface-initiated polymerization of aniline on the surface of aniline-functionalized Si nanoparticles; then, the PANI-grafted Si nanoparticles were wrapped by the GO sheets via π-π interaction and electrostatic attraction between the GO and the PANI. Finally, the GO and PANI were pyrolyzed, and this pyrolyzed PANI layer tightly binds the graphene sheets and the Si nanoparticles together in the composite. The composite materials exhibit better cycling stability and Coulombic efficiency as anodes in lithium ion batteries, as compared to pure Si nanoparticles and physically mixed graphene/Si composites. After 300 cycles at a current density of 2 A/g, the composite electrodes can still deliver a specific capacity of about 900 mAh/g, which corresponds to ∼76% capacity retention. The enhanced performance can be attributed to the absence of surface oxides, the better electronic conductivity, faster ion diffusion rate, and the strong interaction between the graphene sheets and the tightly bound carbon-coated Si nanoparticles.

  10. Substrate-free gas-phase synthesis of graphene sheets.

    Science.gov (United States)

    Dato, Albert; Radmilovic, Velimir; Lee, Zonghoon; Phillips, Jonathan; Frenklach, Michael

    2008-07-01

    We present a novel method for synthesizing graphene sheets in the gas phase using a substrate-free, atmospheric-pressure microwave plasma reactor. Graphene sheets were synthesized by passing liquid ethanol droplets into an argon plasma. The graphene sheets were characterized by transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, and electron diffraction. We prove that graphene can be created without three-dimensional materials or substrates and demonstrate a possible avenue to the large-scale synthesis of graphene.

  11. Method to determine factors contributing to thermoplastic sheet shrinkage

    Science.gov (United States)

    Rensch, Greg J.; Frye, Brad A.

    A test method is presented for the determination of shrinkage behavior in vacuum-formed thermoplastic resin sheeting, as presently simulated for various resin lots, sheet-gage thicknesses, sheet orientations, and mold profiles. The thermoforming machine and vacuum-forming mold characteristics are discussed. It is established that the four variable factors exert statistically significant effects on the shrinkage response of three Declar resin lots, but that these are of no real practical significance for either engineering or manufacturing operations.

  12. On the isothermal geometry of corrugated graphene sheets

    OpenAIRE

    Trzesowski, Andrzej

    2013-01-01

    Variational geometries describing corrugated graphene sheets are proposed. The isothermal thermomechanical properties of these sheets are described by a 2-dimensional Weyl space. The equation that couples the Weyl geometry with isothermal distributions of the temperature of graphene sheets, is formulated. This material space is observed in a 3-dimensional orthogonal configurational point space as regular surfaces which are endowed with a thermal state vector field fulfilling the isothermal th...

  13. Selection of molybdenum sheet for deep drawing applications

    Energy Technology Data Exchange (ETDEWEB)

    Salt, P.J. (Marconi Elliott Avionic Systems Ltd., Borehamwood (UK))

    1982-06-01

    Finished tubes are considered to be an extreme example of the art of deep drawing thin molybdenum sheet. This paper describes an investigation into the manufacture of unalloyed molybdenum tube from sheet material 0.5 mm thick. Metallographic examination of different starting materials revealed the most suitable molybdenum sheet materials for this application and so avoid the conditions that bring about undesirable structures or properties.

  14. Corrosion Behavior of Brazed Zinc-Coated Structured Sheet Metal

    OpenAIRE

    Nikitin, A.; L. Schleuss; R. Ossenbrink; V. Michailov

    2017-01-01

    Arc brazing has, in comparison to arc welding, the advantage of less heat input while joining galvanized sheet metals. The evaporation of zinc is reduced in the areas adjacent to the joint and improved corrosion protection is achieved. In the automotive industry, lightweight design is a key technology against the background of the weight and environment protection. Structured sheet metals have higher stiffness compared to typical automobile sheet metals and therefore they can play an importan...

  15. Greenland ice sheet motion insensitive to exceptional meltwater forcing

    OpenAIRE

    Tedstone, Andrew J.; P. W. Nienow; A. J. Sole; D. W. F. Mair; Cowton, Tom; I. D. Bartholomew; King, M. A.

    2013-01-01

    Changes to the dynamics of the Greenland ice sheet can be forced by various mechanisms including surface-melt-induced ice acceleration and oceanic forcing of marine-terminating glaciers. We use observations of ice motion to examine the surface melt-induced dynamic response of a land-terminating outlet glacier in south-west Greenland to the exceptional melting observed in 2012. During summer, meltwater generated on the Greenland Ice Sheet (GrIS) surface accesses the ice sheet bed, lubricating ...

  16. Evidence of meltwater retention within the Greenland ice sheet

    OpenAIRE

    A. K. Rennermalm; Smith, L.C.; V. W. Chu; J. E. Box; R. R. Forster; van den Broeke, M.

    2012-01-01

    Greenland ice sheet mass losses have increased in recent decades with approximately half of these attributed to increased surface meltwater runoff. However, controls on ice sheet water release, and the magnitude of englacial storage, firn densification, internal refreezing and other hydrologic processes that delay or reduce true water export to the global ocean remain poorly understood. This problem is amplified by scant hydrometerological measurements. Here, ice sheet surface meltwater runof...

  17. Neutral sheet crossings in the distant magnetotail

    Energy Technology Data Exchange (ETDEWEB)

    Heikkila, W.J.; Slavin, J.A.; Smith, E.J.; Baker, D.N.; Zwickl, R.D.

    1985-01-01

    We have analyzed the magnetic field data from ISEE-3 in the distant magnetotail for 18 crossings of the cross-tail current sheet (or so-called natural sheet) to determine the direction of the normal component B/sub z/. The crossings occurred near the middle of the aberrated magnetotail (0 < y < 30 R/sub e, -10 < z < 5) in GSM coordinates, at a distance of about 220 R/sub e/, January 28 to February 12, 1983; in each case the plasma flow velocity was tailward. In 2 cases we found B/sub z/ negative (southward), as would be required with a magnetic neutral line (reconnection line) earthward of the spacecraft. In 12 cases B/sub z/ was clearly northward (B/sub z/ > 0.4 nT), consistent with closed field lines connected to the earth. In 3 cases B/sub z/ was very close to zero; in several instances there was structure in B/sub y/, suggesting localized currents with x or z directions. One may have been a magnetopause crossing. The strong preponderance of northward B/sub z/ favors a model of the magnetotail which is dominated by boundary layer plasma, flowing tailward on closed magnetic field lines, which requires the existence of an electric field in the sense from dusk to dawn. 37 refs., 15 figs., 1 tab.

  18. Tracking millennial-scale Holocene glacial advance and retreat using osmium isotopes: Insights from the Greenland ice sheet

    Science.gov (United States)

    Rooney, Alan D.; Selby, David; Llyod, Jeremy M.; Roberts, David H.; Luckge, Andreas; Sageman, Bradley B.; Prouty, Nancy G.

    2016-01-01

    High-resolution Os isotope stratigraphy can aid in reconstructing Pleistocene ice sheet fluctuation and elucidating the role of local and regional weathering fluxes on the marine Os residence time. This paper presents new Os isotope data from ocean cores adjacent to the West Greenland ice sheet that have excellent chronological controls. Cores MSM-520 and DA00-06 represent distal to proximal sites adjacent to two West Greenland ice streams. Core MSM-520 has a steadily decreasing Os signal over the last 10 kyr (187Os/188Os = 1.35–0.81). In contrast, Os isotopes from core DA00-06 (proximal to the calving front of Jakobshavn Isbræ) highlight four stages of ice stream retreat and advance over the past 10 kyr (187Os/188Os = 2.31; 1.68; 2.09; 1.47). Our high-resolution chemostratigraphic records provide vital benchmarks for ice-sheet modelers as we attempt to better constrain the future response of major ice sheets to climate change. Variations in Os isotope composition from sediment and macro-algae (seaweed) sourced from regional and global settings serve to emphasize the overwhelming effect weathering sources have on seawater Os isotope composition. Further, these findings demonstrate that the residence time of Os is shorter than previous estimates of ∼104 yr.

  19. Large Fleets Lead in Petroleum Reduction (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    Proc, H.

    2011-03-01

    Fact sheet describes Clean Cities' National Petroleum Reduction Partnership, an initiative through which large private fleets can receive support from Clean Cities to reduce petroleum consumption.

  20. Magnetic configurations of the tilted current sheets in magnetotail

    Directory of Open Access Journals (Sweden)

    C. Shen

    2008-11-01

    Full Text Available In this research, the geometrical structures of tilted current sheet and tail flapping waves have been analysed based on multiple spacecraft measurements and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1 The magnetic field lines (MFLs in the tilted current sheet are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the equatorial plane, while the normal of the tilted current sheet leans severely to the dawn or dusk side. (2 The tilted current sheet may become very thin, the half thickness of its neutral sheet is generally much less than the minimum radius of the curvature of the MFLs. (3 In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4 In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1 RE, while the neutral sheet may be very thin, with its half thickness being several tenths of RE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45°. The phase velocities of these flapping waves are several tens km/s, while their periods and wavelengths are several tens of minutes, and several earth radii, respectively. These tail flapping events generally last several hours and occur

  1. Crib sheets and exam performance in a data structures course

    Science.gov (United States)

    Hamouda, Sally; Shaffer, Clifford A.

    2016-01-01

    In this paper, we study the relationship between the use of "crib sheets" or "cheat sheets" and performance on in-class exams. Our extensive survey of the existing literature shows that it is not decisive on the questions of when or whether crib sheets actually help students to either perform better on an exam or better learn the material. We report on our own detailed analysis for a body of crib sheets created for the final exam in a junior-level Data Structures and Algorithms course. We wanted to determine whether there is any feature of the crib sheets that correlates to good exam scores. Exam performance was compared against a number of potential indicators for quality in a crib sheet. We have found that students performed significantly better on questions at the comprehension level of Bloom's taxonomy when their crib sheet contained good information on the topic, while performance on questions at higher levels of the taxonomy did not show correlation to crib sheet contents. We have also seen that students at certain levels of performance on the final exam (specifically, medium-to-high performance) did relatively better on certain questions than other students at that performance level when they had good coverage of that question's topic on their crib sheet.

  2. Present and future changes of ice sheets in a coupled ice sheet-climate model

    Science.gov (United States)

    Kapsch, Marie; Ziemen, Florian; Mikolajewicz, Uwe

    2017-04-01

    The future evolution of the ice sheets covering Greenland and Antarctica is of importance, as ice sheets hold more than 99% of the Earths' freshwater. If released into the oceans, this freshwater could significantly impact the global climate, most prominently the oceanic overturning circulation and the sea-level. To model past and future climate change it is therefore important to integrate ice sheet models (ISMs) into state-of-the-art Earth System Models (ESMs), in order to account for the full range of feedback processes between ice sheets and other climate components. However, the coupling of ISMs into ESMs remains challenging, especially due to the required downscaling of the surface mass balance (SMB) from the low resolution atmospheric grid of the ESM onto the high resolution ice sheet topography. Here we present results from model simulations with the Max Planck Institute ESM (MPI-ESM) coupled to the Parallel ISM (PISM; http://www.pism-docs.org). To bridge the gap between the different model resolutions of the atmospheric component of MPI-ESM and PISM a sophisticated energy balance model (EBM) is used to calculate and downscale the SMB. The modeled SMB for present-day climate conditions shows good agreement with SMB reconstructions from regional climate modeling (e.g. RACMO, MAR). To estimate the effect of different downscaling methods, simulations performed with the EBM are compared to simulations that use a commonly applied positive degree day approach. These comparisons are shown for simulations with present day as well as increasing greenhouse gas concentrations.

  3. Ice_Sheets_CCI: Essential Climate Variables for the Greenland Ice Sheet

    Science.gov (United States)

    Forsberg, R.; Sørensen, L. S.; Khan, A.; Aas, C.; Evansberget, D.; Adalsteinsdottir, G.; Mottram, R.; Andersen, S. B.; Ahlstrøm, A.; Dall, J.; Kusk, A.; Merryman, J.; Hvidberg, C.; Khvorostovsky, K.; Nagler, T.; Rott, H.; Scharrer, M.; Shepard, A.; Ticconi, F.; Engdahl, M.

    2012-04-01

    As part of the ESA Climate Change Initiative (www.esa-cci.org) a long-term project "ice_sheets_cci" started January 1, 2012, in addition to the existing 11 projects already generating Essential Climate Variables (ECV) for the Global Climate Observing System (GCOS). The "ice_sheets_cci" goal is to generate a consistent, long-term and timely set of key climate parameters for the Greenland ice sheet, to maximize the impact of European satellite data on climate research, from missions such as ERS, Envisat and the future Sentinel satellites. The climate parameters to be provided, at first in a research context, and in the longer perspective by a routine production system, would be grids of Greenland ice sheet elevation changes from radar altimetry, ice velocity from repeat-pass SAR data, as well as time series of marine-terminating glacier calving front locations and grounding lines for floating-front glaciers. The ice_sheets_cci project will involve a broad interaction of the relevant cryosphere and climate communities, first through user consultations and specifications, and later in 2012 optional participation in "best" algorithm selection activities, where prototype climate parameter variables for selected regions and time frames will be produced and validated using an objective set of criteria ("Round-Robin intercomparison"). This comparative algorithm selection activity will be completely open, and we invite all interested scientific groups with relevant experience to participate. The results of the "Round Robin" exercise will form the algorithmic basis for the future ECV production system. First prototype results will be generated and validated by early 2014. The poster will show the planned outline of the project and some early prototype results.

  4. Continuous broadband seismic observation on the Greenland Ice Sheet under Greenland Ice Sheet monitoring Network

    Science.gov (United States)

    Tsuboi, Seiji; Kanao, Masaki; Tono, Yoko; Himeno, Tetsuto; Toyokuni, Genti; Childs, Dean; Dahl-Jensen, Trine; anderson, Kent

    2013-04-01

    We have installed the ice sheet broadband seismograph station, called ICE-S (DK.ICESG) in June 2011, in collaboration with IRIS Polar Services under the GreenLand Ice Sheet monitoring Network (GLISN), which is a new, international, broadband seismic capability for Greenland being implemented through the collaboration between Denmark, Canada, France, Germany, Italy, Japan, Norway, Poland, Switzerland, and the USA. The primary purpose of GLISN project is to define the fine structure and detailed mechanisms of glacial earthquakes within the Greenland Ice Sheet. These glacial earthquakes in the magnitude range 4.6-5.1 may be modeled as a large glacial ice mass sliding downhill several meters on its basal surface over duration of 30 to 60 seconds. Glacial earthquakes have been observed at seismic stations within Greenland (Larsen et al, 2006), but the coverage was very sparse and a broadband, real-time seismic network was needed to be installed throughout Greenland's Ice Sheet and perimeter. The National Institute for Polar Research and Japan Agency for Marine-Earth Science and Technology are members of GLISN project and we have started to operate ICESG station since 2011. The station is equipped with a CMG-3T broadband seismometer and a Quanterra Q330 data logger. We have visited the station again in May, 2012 and successfully retrieved one year of continuous records from the broadband seismometer and updated the telemetry system to eventually allow real time monitoring of the station. ICESG station is now daily sending 1 Hz continuous data over the iridium satellite system using RUDICS. The observed three component seismograms demonstrate that the quality of this ice sheet station is good enough to record not only local earthquakes around Greeland but also teleseismic earthquakes. We could record three component broadband seismograms for April 11, 2012 Off the west coast of Northern Sumatra earthquake (Mw8.6). These seismograms show high signal to noise ratio

  5. Metal nanowire-graphene composite transparent electrodes

    Science.gov (United States)

    Mankowski, Trent; Zhu, Zhaozhao; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine; Mansuripur, Masud; Falco, Charlies M.

    2014-10-01

    Silver nanowires with 40 nm diameter and copper nanowires with 150 nm diameter were synthesized using low-temperature routes, and deposited in combination with ultrathin graphene sheets for use as transparent conductors. A systematic and detailed analysis involving nature of capping agent for the metal nanowires, annealing of deposited films, and pre-treatment of substrates revealed critical conditions necessary for preparing high performance transparent conducting electrodes. The best electrodes show ~90% optical transmissivity and sheet resistance of ~10 Ω/□, already comparable to the best available transparent electrodes. The metal nanowire-graphene composite electrodes are therefore well suited for fabrication of opto-electronic and electronic devices.

  6. Multilayer Mg-Stainless Steel Sheets, Twinning and Texture Evolution

    Science.gov (United States)

    Inoue, Junya; Sadeghi, Alireza; Ohmori, Toshinori; Koseki, Toshihiko

    2017-07-01

    In the present study, different combinations of multilayer sheets were prepared from 1 and 2 mm Mg AZ31 along with 0.25, 0.5, and 1 mm 304 L stainless steel. The texture and microstructure of the elongated samples (20 and 30 pct strain) were studied. It was found that the transversal stress plays an important role in both texture evolution and twinning in these composites. The obtained pole figures revealed an axial texture tilt with increasing steel layer volume fraction ( V f). It was found that this is a direct effect of transverse stress, which becomes more significant upon reducing Mg V f. This extra stress component tilts the basal planes away from the original normal direction in monolithic samples. Moreover, our results indicate that with decreasing Mg V f, twinning activity was increased in the 20 pct deformed samples but reduced in the samples with 30 pct elongation. It is known that at high strains where sufficient transverse stress is generated, the activity of prismatic slip is significantly enhanced, which promotes the motion of dislocations and reduces the necessity of twinning. With decreasing Mg V f, stronger transversal stress is generated and Mg reaches the critical threshold of prismatic activity at lower strains.

  7. Evolution of Lava Sheets for LIPs: Types of Local and Regional Trends

    Science.gov (United States)

    Rakhmenkulova, I. F.; Sharapov, V. N.

    2011-12-01

    The North-Atlantic Igneous Province (NAIP), the Permian-Triassic traps of the Siberian Platform (SP), and the volcanic shields of the Hawaiian Ridge can be regarded as the examples of local and regional trends for lava sheets evolution of LIPs. Complex statistical analysis for distribution functions of petrogenic and trace components showed that cyclicity and spatial asymmetry for melt compositions are typical for all lava sheets of LIPs. NAIP has the following features: 1) the formation of continental swell and its rifting; 2) the oceanic basin formation as a system of open basins at the east and the opening of the Central Atlantic to the north with the transverse volcanic zone of the Ferraro Ridge; 3) quick opening of the oceanic basin with the formation and accretion of lava sheet in the centre of the spreading zone (MOR). At the western NAIP part, during the sheet breakage, magnesian melts were forming, in the east - 'typical' trap tholeiitic association with thick lava profiles; oceanic part of the system contains various oceanic basalts. Iceland lava sheet passed through at least three subsequent formation stages with typical petrochemical igneous rock complexes. There are local petrochemical trends in the Iceland sheet: as the basalt crust thickens, acid melt amounts increase. The Permian-Triassic SP traps at the southern part of the Khatanga Rift (where the province started to develop spatially) have the following zones: layered profiles of tuffaceous rocks in the Tunguska Syncline, with various quantities of lava flows in the upper part of the profiles; to the south, within the holes between the net of fissure and central lava-breccia volcanic structures, reloaded tuff material is located; more to the south this structural zone changes to swarms of dyke-diatreme structures having typical near-vent depressions. The explosive coefficient within these zones increases from the north to the south. In the western part of trap zone there is a petrochemical zoning

  8. Composition measurements in the dusk flank magnetosphere

    Science.gov (United States)

    Fuselier, S. A.; Elphic, R. C.; Gosling, J. T.

    1999-03-01

    The dusk flank magnetosphere exhibits significant structure. Several regions have been identified, including the plasma sheet, mantle, and low latitude boundary layer. Transitions from one region to the next, for example from the mantle to the plasma sheet, can be abrupt or indistinct. In addition, the density within the flank mantle can range over several orders of magnitude. Although there is significant structure in this region of the magnetosphere, individual regions often can be distinguished by their energy spectra and ion composition. ISEE Fast Plasma Experiment and Plasma Composition Experiment data are used to examine the composition of the mantle and to study a set of transitions from the mantle to the plasma sheet where plasmas with mantle-like and plasma sheet-like energies mix. This study indicates that the variability of the mantle density is largely due to variability in the solar wind component (H+ and He2+); the ionospheric plasma (O+) density is roughly constant. Similarly, the plasma with mantle-like energy found in the mixed region is largely of solar wind origin.

  9. Thermo-responsive methylcellulose hydrogels as temporary substrate for cell sheet biofabrication.

    Science.gov (United States)

    Altomare, Lina; Cochis, Andrea; Carletta, Andrea; Rimondini, Lia; Farè, Silvia

    2016-05-01

    Methylcellulose (MC), a water-soluble polymer derived from cellulose, was investigated as a possible temporary substrate having thermo-responsive properties favorable for cell culturing. MC-based hydrogels were prepared by a dispersion technique, mixing MC powder (2, 4, 6, 8, 10, 12 % w/v) with selected salts (sodium sulphate, Na2SO4), sodium phosphate, calcium chloride, or phosphate buffered saline, to evaluate the influence of different compositions on the thermo-responsive behavior. The inversion test was used to determine the gelation temperatures of the different hydrogel compositions; thermo-mechanical properties and thermo-reversibility of the MC hydrogels were investigated by rheological analysis. Gelation temperatures and rheological behavior depended on the MC concentration and type and concentration of salt used in hydrogel preparation. In vitro cytotoxicity tests, performed using L929 mouse fibroblasts, showed no toxic release from all the tested hydrogels. Among the investigated compositions, the hydrogel composed of 8 % w/v MC with 0.05 M Na2SO4 had a thermo-reversibility temperature at 37 °C. For that reason, this formulation was thus considered to verify the possibility of inducing in vitro spontaneous detachment of cells previously seeded on the hydrogel surface. A continuous cell layer (cell sheet) was allowed to grow and then detached from the hydrogel surface without the use of enzymes, thanks to the thermo-responsive behavior of the MC hydrogel. Immunofluorescence observation confirmed that the detached cell sheet was composed of closely interacting cells.

  10. Fabrication of polytetrafluoroethylene/carbon fiber composites using radiation crosslinking

    Science.gov (United States)

    Oshima, Akihiro; Udagawa, Akira; Tanaka, Shigeru

    2001-07-01

    A fabrication method for fiber-reinforced plastic (FRP) composites based on carbon fibers and polytetrafluoroethylene (PTFE) which was crosslinked by electron beam (EB) irradiation under specific conditions was studied. Though the fabricated composite showed high mechanical properties compared with a ready-made PTFE composite (non-crosslinked PTFE with 5˜20 wt% filler), mechanical properties of laminated panels were a bit poor compared with those of usual FRP. It was found that the toughness of the PTFE matrix is poor in the composite. On the other hand, the one-ply sheet of carbon fibers and crosslinked PTFE composite showed good mechanical properties for sheet-shape materials. The wettability of the obtained crosslinked PTFE composite is hardly changed by crosslinking and reinforcement.

  11. Fabrication of polytetrafluoroethylene/carbon fiber composites using radiation crosslinking

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, Akihiro E-mail: aks@taka.jaeri.go.jp; Udagawa, Akira; Tanaka, Shigeru

    2001-07-01

    A fabrication method for fiber-reinforced plastic (FRP) composites based on carbon fibers and polytetrafluoroethylene (PTFE) which was crosslinked by electron beam (EB) irradiation under specific conditions was studied. Though the fabricated composite showed high mechanical properties compared with a ready-made PTFE composite (non-crosslinked PTFE with 5{approx}20 wt% filler), mechanical properties of laminated panels were a bit poor compared with those of usual FRP. It was found that the toughness of the PTFE matrix is poor in the composite. On the other hand, the one-ply sheet of carbon fibers and crosslinked PTFE composite showed good mechanical properties for sheet-shape materials. The wettability of the obtained crosslinked PTFE composite is hardly changed by crosslinking and reinforcement.

  12. Theoretical analysis of sheet metal formability

    Science.gov (United States)

    Zhu, Xinhai

    Sheet metal forming processes are among the most important metal-working operations. These processes account for a sizable proportion of manufactured goods made in industrialized countries each year. Furthermore, to reduce the cost and increase the performance of manufactured products, in addition to the environmental concern, more and more light weight and high strength materials have been used as a substitute to the conventional steel. These materials usually have limited formability, thus, a thorough understanding of the deformation processes and the factors limiting the forming of sound parts is important, not only from a scientific or engineering viewpoint, but also from an economic point of view. An extensive review of previous studies pertaining to theoretical analyses of Forming Limit Diagrams (FLDs) is contained in Chapter I. A numerical model to analyze the neck evolution process is outlined in Chapter II. With the use of strain gradient theory, the effect of initial defect profile on the necking process is analyzed. In the third chapter, the method proposed by Storen and Rice is adopted to analyze the initiation of localized neck and predict the corresponding FLDs. In view of the fact that the width of the localized neck is narrow, the deformation inside the neck region is constrained by the material in the neighboring homogeneous region. The relative rotation effect may then be assumed to be small and is thus neglected. In Chapter IV, Hill's 1948 yield criterion and strain gradient theory are employed to obtain FLDs, for planar anisotropic sheet materials by using bifurcation analysis. The effects of the strain gradient coefficient c and the material anisotropic parameters R's on the orientation of the neck and FLDs are analyzed in a systematic manner and compared with experiments. In Chapter V, Hill's 79 non-quadratic yield criterion with a deformation theory of plasticity is used along with bifurcation analyses to derive a general analytical

  13. Self-Construction from 2D to 3D: One-Pot Layer-by-Layer Assembly of Graphene Oxide Sheets Held Together by Coordination Polymers.

    Science.gov (United States)

    Zakaria, Mohamed B; Li, Cuiling; Ji, Qingmin; Jiang, Bo; Tominaka, Satoshi; Ide, Yusuke; Hill, Jonathan P; Ariga, Katsuhiko; Yamauchi, Yusuke

    2016-07-11

    Deposition of Ni-based cyanide bridged coordination polymer (NiCNNi) flakes onto the surfaces of graphene oxide (GO) sheets, which allows precise control of the resulting lamellar nanoarchitecture by in situ crystallization, is reported. GO sheets are utilized as nucleation sites that promote the optimized crystal growth of NiCNNi flakes. The NiCNNi-coated GO sheets then self-assemble and are stabilized as ordered lamellar nanomaterials. Regulated thermal treatment under nitrogen results in a Ni3 C-GO composite with a similar morphology to the starting material, and the Ni3 C-GO composite exhibits outstanding electrocatalytic activity and excellent durability for the oxygen reduction reaction.

  14. Strengthening of reinforced concrete beams with basalt-based FRP sheets: An analytical assessment

    Science.gov (United States)

    Nerilli, Francesca; Vairo, Giuseppe

    2016-06-01

    In this paper the effectiveness of the flexural strengthening of RC beams through basalt fiber-reinforced sheets is investigated. The non-linear flexural response of RC beams strengthened with FRP composites applied at the traction side is described via an analytical formulation. Validation results and some comparative analyses confirm soundness and consistency of the proposed approach, and highlight the good mechanical performances (in terms of strength and ductility enhancement of the beam) produced by basalt-based reinforcements in comparison with traditional glass or carbon FRPs.

  15. A molecular dynamics study on the interaction between epoxy and functionalized graphene sheets

    Science.gov (United States)

    Melro, L. S.; Pyrz, R.; Jensen, L. R.

    2016-07-01

    The interaction between graphene and epoxy resin was studied using molecular dynamics simulations. The interfacial shear strength and pull out force were calculated for functionalised graphene layers (carboxyl, carbonyl, and hydroxyl) and epoxy composites interfaces. The influence of functional groups, as well as their distribution and coverage density on the graphene sheets were also analysed through the determination of the Young's modulus. Functionalisation proved to be detrimental to the mechanical properties, nonetheless according to interfacial studies the interaction between graphene and epoxy resin increases.

  16. Morphology, Tensile Strength and Oil Resistance of Gum Rubber Sheets Prepared from Lignin Modified Natural Rubber

    Directory of Open Access Journals (Sweden)

    Asrul M.

    2014-07-01

    Full Text Available The paper describes the preparation of lignin filled natural rubber latex composite and its subsequent use to obtain lignin modified rubber. Two types of lignin i.e.: rubber wood and commercial alkali lignin were used as rubber filler. Gum rubber sheets were prepared from the lignin modified rubber and their properties were compared to Standard Malaysian Rubber (SMR 20 and a type of rubber obtained from the coagulation of high ammonia latex. Rubber morphology was investigated using Scanning Electron Microscope on the cross-sectional area of cryo-fractured samples. Oil resistance of the rubber sheets was determined by measuring the mass change before and after ASTM IRM 903 oil immersion, while the tensile strengths were determined according to ASTM D412 standard. Low values of tensile strength obtained for the commercial alkali lignin modified rubber sheet relative to the rest of the rubber samples was attributed to poor lignin dispersion. This occurrence was substantiated by the SEM analysis of cryo-fractured samples where crazes and inhomogeneity was observed. Nonetheless, both lignin modified rubbers exhibited higher level of oil resistance compared to SMR 20. This is due to the nature of lignin as a hydrophilic component and its presence in the rubber matrix complicates the oil diffusion process into rubber.

  17. Sheet resistance of alumina ceramic after high energy implantation of tantalum ions

    Energy Technology Data Exchange (ETDEWEB)

    Savkin, Konstantin P., E-mail: savkinkp@mail2000.ru [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Bugaev, Alexey S., E-mail: bugaev@opee.hcei.tsc.ru [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Nikolaev, Alexey G., E-mail: nik@opee.hcei.tsc.ru [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Oks, Efim M., E-mail: oks@opee.hcei.tsc.ru [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Shandrikov, Maxim V., E-mail: shandrikov@opee.hcei.tsc.ru [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Yushkov, Georgy Yu., E-mail: gyushkov@mail.ru [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Tyunkov, Andrey V., E-mail: tyunkov@opee.hcei.tsc.ru [Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Avenue, 634050 Tomsk (Russian Federation); Savruk, Elena V., E-mail: savruk@mail.ru [Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Avenue, 634050 Tomsk (Russian Federation)

    2014-08-15

    Highlights: • Tantalum ions with the average energy about 145 keV were implanted in the surfaces of flat polycrystalline alumina samples. • The sheet resistance of implanted ceramic reduced after implantation with increasing of the implanted dose. • Normalized surface conductivity of treated alumina ceramic reduced only on 1% during 200 days after finishing the implantation process. • Creation of weak conducting layer on the surface of the ceramic insulator electric field strength of the flashover increases more than 25%. - Abstract: The results of investigation of the sheet resistance of alumina ceramic as a function of the fluence of implanted metal ions are presented. Tantalum ions with the average energy about 145 keV were used in experiments. Estimation of the sheet resistance was performed from analysis of volt–ampere characteristics by measuring the leakage current at a voltage between 100 V and several kilovolts, which was applied at a small area of the implanted surface. Energy dispersive X-ray analysis was used to determine composition of elements in the surface of the implanted ceramics. As a practical application of research results, it was shown that, after the creation of a weak conducting layer on the surface of the ceramic insulator, the electric field strength of the flashover increases by more than 25%.

  18. Tunable wideband-directive thermal emission from SiC surface using bundled graphene sheets

    Science.gov (United States)

    Inampudi, Sandeep; Mosallaei, Hossein

    2017-09-01

    Coherent thermal radiation emitters based on diffraction gratings inscribed on surface of a polar material, such as silicon carbide, always possess high angular dispersion resulting in wideband-dispersive or monochromatic-directive emission. In this paper, we identify roots of the high angular dispersion as the rapid surface phonon polariton (SPhP) resonance of the material surface and the misalignment of the dispersion curve of the diffraction orders of the grating with respect to light line. We minimize the rapid variation of SPhP resonance by compensating the material dispersion using bundled graphene sheets and mitigate the misalignment by a proper choice of the grating design. Utilizing a modified form of rigorous coupled wave analysis to simultaneously incorporate atomic-scale graphene sheets and bulk diffraction gratings, we accurately compute the emissivity profiles of the composite structure and demonstrate reduction in the angular dispersion of thermal emission from as high as 30∘ to as low as 4∘ in the SPhP dominant wavelength range of 11-12 μ m . In addition, we demonstrate that the graphene sheets via their tunable optical properties allow a fringe benefit of dynamical variation of the angular dispersion to a wide range.

  19. Microbial oxidation as a methane sink beneath the West Antarctic Ice Sheet

    Science.gov (United States)

    Michaud, Alexander B.; Dore, John E.; Achberger, Amanda M.; Christner, Brent C.; Mitchell, Andrew C.; Skidmore, Mark L.; Vick-Majors, Trista J.; Priscu, John C.

    2017-08-01

    Aquatic habitats beneath ice masses contain active microbial ecosystems capable of cycling important greenhouse gases, such as methane (CH4). A large methane reservoir is thought to exist beneath the West Antarctic Ice Sheet, but its quantity, source and ultimate fate are poorly understood. For instance, O2 supplied by basal melting should result in conditions favourable for aerobic methane oxidation. Here we use measurements of methane concentrations and stable isotope compositions along with genomic analyses to assess the sources and cycling of methane in Subglacial Lake Whillans (SLW) in West Antarctica. We show that sub-ice-sheet methane is produced through the biological reduction of CO2 using H2. This methane pool is subsequently consumed by aerobic, bacterial methane oxidation at the SLW sediment-water interface. Bacterial oxidation consumes >99% of the methane and represents a significant methane sink, and source of biomass carbon and metabolic energy to the surficial SLW sediments. We conclude that aerobic methanotrophy may mitigate the release of methane to the atmosphere upon subglacial water drainage to ice sheet margins and during periods of deglaciation.

  20. Synthesis and Characterization of the in Situ Bulk Polymerization of PMMA Containing Graphene Sheets Using Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Mohammad A. Aldosari

    2013-03-01

    Full Text Available Polymethylmethacrylate–graphene (PMMA/RGO nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO and methylmethacrylate monomers (MMA were polymerized using a bulk polymerization method with a free radical initiator. After the addition of the reducing agent hydrazine hydrate (HH, the product was reduced via microwave irradiation (MWI to obtain R-(GO-PMMA composites. In the second approach, a mixture of graphite sheets (RGO and MMA monomers were polymerized using a bulk polymerization method with a free radical initiator to obtain RGO-(PMMA composites. The composites were characterized by FTIR, 1H-NMR and Raman spectroscopy and XRD, SEM, TEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability compared with the composites prepared without MWI.