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Sample records for isostatically pressed beryllium-aluminum-silver

  1. METHOD FOR SOLVENT-ISOSTATIC PRESSING

    DOEpatents

    Archibald, P.B.

    1962-09-18

    This invention provides a method for producing densely compacted bodies having relatively large dimensions. The method comprises the addition of a small quantity of a suitable solvent to a powder which is to be compacted. The solvent- moistened powder is placed inside a flexible bag, and the bag is suspended in an isostatic press. The solvent is squeezed out of the powder by the isostatic pressure, and the resulting compacted body is recovered. The presence of the solvent markedly decreases the proportion of void space in the powder, thereby resulting in a denser, more homogeneous compact. Another effect of the solvent is that it allows the isostatic pressing operation to be conducted at substantially lower pressures than are conventionally employed. (AEC)

  2. Glass Coats For Hot Isostatic Pressing

    NASA Technical Reports Server (NTRS)

    Ecer, Gunes M.

    1989-01-01

    Surface voids sealed from pressurizing gas. Coating technique enables healing of surface defects by hot isostatic pressing (HIP). Internal pores readily closed by HIP, but surface voids like cracks and pores in contact with pressurizing gas not healed. Applied to casting or weldment as thick slurry of two glass powders: one melts at temperature slightly lower than used for HIP, and another melts at higher temperature. For example, powder is glass of 75 percent SiO2 and 25 percent Na2O, while other powder SiO2. Liquid component of slurry fugitive organic binder; for example, mixture of cellulose acetate and acetone. Easy to apply, separates voids from surrounding gas, would not react with metal part under treatment, and easy to remove after pressing.

  3. Glass Coats For Hot Isostatic Pressing

    NASA Technical Reports Server (NTRS)

    Ecer, Gunes M.

    1989-01-01

    Surface voids sealed from pressurizing gas. Coating technique enables healing of surface defects by hot isostatic pressing (HIP). Internal pores readily closed by HIP, but surface voids like cracks and pores in contact with pressurizing gas not healed. Applied to casting or weldment as thick slurry of two glass powders: one melts at temperature slightly lower than used for HIP, and another melts at higher temperature. For example, powder is glass of 75 percent SiO2 and 25 percent Na2O, while other powder SiO2. Liquid component of slurry fugitive organic binder; for example, mixture of cellulose acetate and acetone. Easy to apply, separates voids from surrounding gas, would not react with metal part under treatment, and easy to remove after pressing.

  4. Hot isostatic pressing of intermetallic powders

    NASA Astrophysics Data System (ADS)

    Schaefer, R. J.; Kushner, B. G.

    The application of the intelligent processing of materials (IPM) approach to powder densification by hot isostatic pressing (HIP) is made possible by the development of in situ sensors, process models and adaptive control strategies. The challenge is to optimize the process schedule for new materials to achieve densification, shape and microstructural goals. The development of an IPM system for HIP of intermetallic powders is described. The primary sensor used in this system employs eddy currents to measure changes of sample dimensions, while the process model is that of Ashby et al., reformulated to more closely describe real materials in real HIP process cycles. Process cycles are developed by combining a knowledge base derived from experts with the process model refined by sensor measurements.

  5. Hot Isostatic Pressing of 60-Nitinol

    NASA Technical Reports Server (NTRS)

    Stanford, Malcolm K.

    2015-01-01

    The effects of varying the time, temperature and pressure during consolidation of 60-Nitinol (Nickel Titanium alloy) by hot isostatic pressing (HIP) were examined. Six HIP cycles with a cycle time of either 2 or 20 hours, temperature of 900 or 1000 degrees Centigrade, and a chamber pressure of either 100 or 200 millipascals were used. The cycle representing the shortest cycle time at the highest temperature and pressure (2 hours/1000 degrees Centigrade/200 millipascals) produced material with the highest hardness (720 Vickers Pyramid Number (HV)). A modest increase in average grain size and significant porosity reduction were observed in material subjected to the longest cycle time at the highest temperature, regardless of the pressure applied. The intent of this study is to facilitate the technology transfer involved in the processing of this material.

  6. Hot isostatic press waste option study report

    SciTech Connect

    Russell, N.E.; Taylor, D.D.

    1998-02-01

    A Settlement Agreement between the Department of Energy and the State of Idaho mandates that all high-level radioactive waste now stored at the Idaho Chemical Processing Plant be treated so that it is ready to move out of Idaho for disposal by the target date of 2035. This study investigates the immobilization of all Idaho Chemical Processing Plant calcine, including calcined sodium bearing waste, via the process known as hot isostatic press, which produces compact solid waste forms by means of high temperature and pressure (1,050 C and 20,000 psi), as the treatment method for complying with the settlement agreement. The final waste product would be contained in stainless-steel canisters, the same type used at the Savannah River Site for vitrified waste, and stored at the Idaho National Engineering and Environmental Laboratory until a national geological repository becomes available for its disposal. The waste processing period is from 2013 through 2032, and disposal at the High Level Waste repository will probably begin sometime after 2065.

  7. Crack-Free, Nondistorting Can For Hot Isostatic Pressing

    NASA Technical Reports Server (NTRS)

    Juhas, John J.

    1991-01-01

    New method of canning specimens made of composites of arc-sprayed and plasma-sprayed tape reduces outgassing and warping during hot isostatic pressing. Produces can having reliable, crack-free seal and thereby helps to ensure pressed product of high quality. Specimen placed in ring of refractory metal between two face sheets, also of refractory metal. Assembly placed in die in vacuum hot press, where simultaneously heated and pressed until plates become diffusion-welded to ring, forming sealed can around specimen. Specimen becomes partially densified, and fits snugly within can. Ready for further densification by hot isostatic pressing.

  8. Joining of ceramics of different biofunction by hot isostatic pressing

    SciTech Connect

    Li, Jianguo . Center for Dental Technology and Biomaterials); Harmansson, L. ); Soeremark, R. . Dept. of Prosthodontics)

    1993-10-01

    Monolithic zirconia (Z) and zirconia-hydroxyapatite (Z/HA) composites were joined by cold isostatic pressing (CIP at 300 MPa) and subsequently by glass-encapsulated hot isostatic pressing (HIP at 1225 C, 1 h and 200 MPa). The physical and mechanical properties of the materials were measured. The fracture surface was studied using a light microscope. The results indicate a strength level of the joint similar to that of the corresponding composite material (Z/HA), 845 and 860 MPa, respectively. Similar experiments with monolithic alumina (A) and alumina-hydroxyapatite (A/HA) were carried out without success. Cracking occurred in the joint area during the cold isostatic pressing process. It seems that ceramics with high green strength and similar green density are essential when joining ceramics by combined CIP and HIP processes.

  9. Hot Isostatic Press (HIP) vitrification of radwaste concretes

    SciTech Connect

    Siemer, D.D.; Scheetz, B.; Gougar, M.L.D.

    1995-12-01

    Properly formulated and properly ``canned`` radwaste concretes can be readily hot-isostatically-pressed (HIPed) into materials that exhibit performance equivalent to typical radwaste-type glasses. The HIPing conditions (temperature/pressure) required to turn a concrete waste form into a ``vitrified`` waste form are quite mild and therefore consistent with both safety and high productivity. This paper describes the process and its products with reference to its potential application to Idaho Chemical Processing Plant (ICPP) reprocessing wastes.

  10. Hot Isostatically Pressed Sm(2)(TM)17 Magnets.

    DTIC Science & Technology

    1985-04-01

    SUB. GR. HIP - hot isostatic pressing Stepped aging treatment Samarium - transition metal magnets f Samarium , Copper, Iron, Zirconium, Cobalt magnets 1...5 ptaI2 TABLE OF CONTENTS Section Page INTRODUCTION...............................................1 2 EXPERIMENTAL METHODS ...values of BR and Hci of the Nd-Fe-B type materials, however, have precluded their use in several critical applications such as in microwave devices and

  11. Microstructural Formations and Phase Transformation Pathways in Hot Isostatically Pressed Tantalum Carbides

    DTIC Science & Technology

    2012-01-01

    REPORT Microstructural formations and phase transformation pathways in hot isostatically pressed tantalum carbides 14. ABSTRACT 16. SECURITY...CLASSIFICATION OF: A series of XTa:(1 X)C (0.5 < X < 1) compositions have been fabricated by hot isostatic pressing (HIP) of Ta and TaC powder blends...ANSI Std. Z39.18 - Microstructural formations and phase transformation pathways in hot isostatically pressed tantalum carbides Report Title ABSTRACT A

  12. High-pressure combinatorial process integrating hot isostatic pressing.

    PubMed

    Fujimoto, Kenjiro; Morita, Hiroki; Goshima, Yuji; Ito, Shigeru

    2013-12-09

    A high-pressure combinatorial process integrating hot isostatic pressing (HIP) was developed by providing a reaction vessel with a high-pressure tightness based on a commercial flange. The reaction vessel can be used up to 200 MPa and 500 °C under HIP processing condition. Preparation of spinel-type MgAl2O4 from Mg(OH)2, Al(OH)3 and AlOOH was performed using the reaction vessel under 200 MPa and 500 °C as demonstration. The entire powder library was characterized using powder X-ray diffraction patterns, and the single phase of spinel-type MgAl2O4 was obtained from Mg(OH)2+Al(OH)3. These assessments corresponded with previously published data.

  13. The Densification of Molybdenum and Molybdenum Alloy Powders Using Hot Isostatic Pressing.

    DTIC Science & Technology

    1985-08-01

    TECHNICAL REPORT ARLCB-TR-85025 00 THE DENSIFICATION OF MOLYBDENUM (n AND MOLYBDENUM ALLOY POWDERS USING HOT ISOSTATIC PRESSING J. BARRANCO I. AHMAD S...ISOSTATIC PRESSING Final 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(o) . CONTRACT OR GRANT NUMBER(e) J. Barranco , I. Ahmad, S. Isserow, and R. Warenchak

  14. Hydroxyapatite coatings on Ti produced by hot isostatic pressing.

    PubMed

    Herø, H; Wie, H; Jørgensen, R B; Ruyter, I E

    1994-03-01

    Plasma spraying is a technique currently used in the production of HA-coated titanium implants. These coatings have been shown to be porous; they dissolve and have a weak bond to the substrate. The long-term interface strength has been questioned in particular. The aim of the present work was to produce HA coatings without the shortcomings of those produced by plasma spraying. Hot isostatic pressing (HIP) at 850 degrees C and 1000 bar with no holding time was applied for this purpose. Initially, the HA powder was mixed with water and air sprayed on the Ti substrate. The Ti specimens were then cold-pressed, enclosed by a protective Pt foil, and encapsulated in an evacuated glass ampulla. Subsequent to HIP, the glass and the Pt foil were removed. These coatings were denser than those produced by plasma spraying. The bonding was measured to be > 62 MPa, which is considered to be satisfactory. The structure of the coating was checked by X-ray diffraction and IR spectroscopy, and was found to correspond to that of HA. Some cracks were observed in the coating running predominantly vertical to the surface. Whether these are acceptable has to be verified by in vivo experiments.

  15. Effect of hot isostatic pressing on reaction-bonded silicon nitride

    NASA Technical Reports Server (NTRS)

    Watson, G. K.; Moore, T. J.; Millard, M. L.

    1984-01-01

    Specimens of nearly theoretical density have been obtained through the isostatic hot pressing of reaction-bonded silicon nitride under 138 MPa of pressure for two hours at 1850, 1950, and 2050 C. An amorphous phase that is introduced by the hot isostatic pressing partly accounts for the fact that while room temperature flexural strength more than doubles, the 1200 C flexural strength increases significantly only after pressing at 2050 C.

  16. Process and equipment development for hot isostatic pressing treatability study

    SciTech Connect

    Bateman, Ken; Wahlquist, Dennis; Malewitz, Tim

    2015-03-01

    Battelle Energy Alliance (BEA), LLC, has developed processes and equipment for a pilot-scale hot isostatic pressing (HIP) treatability study to stabilize and volume reduce radioactive calcine stored at Idaho National Laboratory (INL). In 2009, the U. S. Department of Energy signed a Record of Decision with the state of Idaho selecting HIP technology as the method to treat 5,800 yd^3 (4,400 m^3) of granular zirconia and alumina calcine produced between 1953 and 1992 as a waste byproduct of spent nuclear fuel reprocessing. Since the 1990s, a variety of radioactive and hazardous waste forms have been remotely treated using HIP within INL hot cells. To execute the remote process at INL, waste is loaded into a stainless-steel or aluminum can, which is evacuated, sealed, and placed into a HIP furnace. The HIP simultaneously heats and pressurizes the waste, reducing its volume and increasing its durability. Two 1 gal cans of calcine waste currently stored in a shielded cask were identified as candidate materials for a treatability study involving the HIP process. Equipment and materials for cask-handling and calcine transfer into INL hot cells, as well as remotely operated equipment for waste can opening, particle sizing, material blending, and HIP can loading have been designed and successfully tested. These results demonstrate BEA’s readiness for treatment of INL calcine.

  17. High-strength silicon carbides by hot isostatic pressing

    NASA Technical Reports Server (NTRS)

    Dutta, Sunil

    1988-01-01

    Silicon carbide has strong potential for heat engine hardware and other high-temperature applications because of its low density, good strength, high oxidation resistance, and good high-temperature creep resistance. Hot isostatic pressing (HIP) was used for producing alpha and beta silicon carbide (SiC) bodies with near-theoretical density, ultrafine grain size, and high strength at processing temperatures of 1900 to 2000 C. The HIPed materials exhibited ultrafine grain size. Furthermore, no phase transformation from beta to alpha was observed in HIPed beta-SiC. Both materials exhibited very high average flexural strength. It was also shown that alpha-SiC bodies without any sintering aids, when HIPed to high final density, can exhibit very high strength. Fracture toughness K (sub C) values were determined to be 3.6 to 4.0 MPa m (sup 1/2) for HIPed alpha-SiC and 3.7 to 4.1 MPa m (sup 1/2) for HIPed beta-SiC. In the HIPed specimens strength-controlling flaws were typically surface related. In spite of improvements in material properties such as strength and fracture toughness by elimination of the larger strength-limiting flaws and by grain size refinement, HIPing has no effect on the Weibull modulus.

  18. Summary of Calcine Disposal Development Using Hot Isostatic Pressing

    SciTech Connect

    Bateman, Ken; Wahlquist, Dennis; Hart, Edward; McCartin, William

    2015-03-01

    Battelle Energy Alliance, LLC, has demonstrated the effectiveness of the hot isostatic press (HIP) process for treatment of hazardous high-level waste known as calcine that is stored at the Idaho Nuclear Technology and Engineering Center (INTEC) at Idaho National Laboratory. HIP trials performed with simulated calcines at Idaho National Laboratory’s Materials and Fuels Complex and an Australian Nuclear Science and Technology Organization facility from 2007 to 2010 produced a dense, monolithic waste form with increased chemical durability and effective (storage) volume reductions of ~10 to ~70% compared to granular calcine forms. In December 2009, the U.S. Department of Energy signed an amended Record of Decision selecting HIP technology as the treatment method for the 4,400 m3 of granular zirconia and alumina calcine stored at INTEC. Testing showed that HIP treatment reduces the risks associated with radioactive and hazardous constituent release, post-production handling, and long-term (repository) storage of calcines and would result in estimated storage cost savings in the billions of dollars. Battelle Energy Alliance has the ability to complete pilot-scale HIP processing of INTEC calcine, which is the next necessary step in implementing HIP processing as a calcine treatment method.

  19. High-strength silicon carbides by hot isostatic pressing

    NASA Technical Reports Server (NTRS)

    Dutta, Sunil

    1989-01-01

    Silicon carbide has strong potential for heat engine hardware and other high-temperature applications because of its low density, good strength, high oxidation resistance, and good high-temperature creep resistance. Hot isostatic pressing (HIP) was used for producing alpha and beta silicon carbide (SiC) bodies with near-theoretical density, ultrafine grain size, and high strength at processing temperatures of 1900 to 2000 C. The HIPed materials exhibited ultrafine grain size. Furthermore, no phase transformation from beta to alpha was observed in HIPed beta-SiC. Both materials exhibited very high average flexural strength. It was also shown that alpha-SiC bodies without any sintering aids, when HIPed to high final density, can exhibit very high strength. Fracture toughness K (sub C) values were determined to be 3.6 to 4.0 MPa m (sup 1/2) for HIPed alpha-SiC and 3.7 to 4.1 MPa m (sup 1/2) for HIPed beta-SiC. In the HIPed specimens strength-controlling flaws were typically surface related. In spite of improvements in material properties such as strength and fracture toughness by elimination of the larger strength-limiting flaws and by grain size refinement, HIPing has no effect on the Weibull modulus.

  20. High-strength silicon carbides by hot isostatic pressing

    NASA Technical Reports Server (NTRS)

    Dutta, Sunil

    1989-01-01

    Silicon carbide has strong potential for heat engine hardware and other high-temperature applications because of its low density, good strength, high oxidation resistance, and good high-temperature creep resistance. Hot isostatic pressing (HIP) was used for producing alpha and beta silicon carbide (SiC) bodies with near-theoretical density, ultrafine grain size, and high strength at processing temperatures of 1900 to 2000 C. The HIPed materials exhibited ultrafine grain size. Furthermore, no phase transformation from beta to alpha was observed in HIPed beta-SiC. Both materials exhibited very high average flexural strength. It was also shown that alpha-SiC bodies without any sintering aids, when HIPed to high final density, can exhibit very high strength. Fracture toughness K (sub C) values were determined to be 3.6 to 4.0 MPa m (sup 1/2) for HIPed alpha-SiC and 3.7 to 4.1 MPa m (sup 1/2) for HIPed beta-SiC. In the HIPed specimens strength-controlling flaws were typically surface related. In spite of improvements in material properties such as strength and fracture toughness by elimination of the larger strength-limiting flaws and by grain size refinement, HIPing has no effect on the Weibull modulus.

  1. Producing metal parts with selective laser sintering/hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Das, Suman; Wohlert, Martin; Beaman, Joseph J.; Bourell, David L.

    1998-12-01

    Selective laser sintering/hot isostatic pressing is a hybrid direct laser fabrication method that combines the strengths of both processes. Selective laser sintering can produce complexly shaped metal components with an integral, gas-impermeable skin. These components can then be directly post-processed to full density by containerless hot isostatic pressing. The use of the hybrid fabrication method, envisioned as a rapid, low-cost replacement for conventional metal-can hot isostatic pressing, is currently being studied for alloy 625 and Ti-6Al-4V alloys. The micro-structure and mechanical properties of selective-laser-sintering processed and hot isostatically pressed post-processed material compare well with those of conventionally processed material.

  2. Removal of glass adhered to sintered ceramics in hot isostatic pressing

    NASA Technical Reports Server (NTRS)

    1985-01-01

    In the hot isostatic pressing of ceramic materials in molten glass using an inert gas as a pressing medium, glass adhered to the sintered ceramics is heated to convert it to a porous glass and removed. Thus, Si3N4 powder was compacted at 5000 kg/sq cm, coated with a 0.5 mm thick BN, embedded in Pyrex glass in a graphite crucible, put inside a hot isostatic press containing Argon, hot pressed at 1750 C and 100 kg/sq cm; cooled, taken out from the crucible, heated at 1100 C for 30 minutes, cooled, and then glass adhered to the sintered body was removed.

  3. Hot isostatic pressing of direct selective laser sintered metal components

    NASA Astrophysics Data System (ADS)

    Wohlert, Martin Steven

    2000-10-01

    A new manufacturing process combining the benefits of Selective Laser Sintering (SLS) and Hot Isostatic Pressing (HIP) has been developed to permit Rapid Prototyping of high performance metal components. The new process uses Direct Metal SLS to produce a gas impermeable HIP container from the same powdered material that will eventually compose the bulk of the part. The SLS generated capsule performs the functions of the sheet metal container in traditional HIP, but unlike a sheet metal container, the SLSed capsule becomes an integral part of the final component. Additionally, SLS can produce a capsule of far greater geometric complexity than can be achieved by sheet metal forming. Two high performance alloys, Ti-6Al-4V and Inconel 625, were selected for use in the development of the new process. HIP maps were constructed to predict the densification rate of the two materials during HIP processing. Comparison to experimentally determined densification behavior indicated that the maps provide a useful qualitative description of densification rates; however, the accuracy of quantitative predictions was greatly enhanced by tuning key material parameters based on a limited number of experimental HIP cycles. Microstructural characterization of SLS + HIP samples revealed two distinct regions within the components. The outer SLS processed capsule material exhibited a relatively coarse microstructure comparable to a cast, or multi-layer welded structure. No layer boundaries were discernible in the SLS material, with grains observed to grow epitaxially from previously deposited material. The microstructure of the HIP consolidated core material was similar to conventionally HIP processed powder materials, featuring a fine grain structure and preserved prior particle boundaries. The large variation in grain size between the capsule and core materials was reflected in hardness measurements conducted on the Alloy 625 material; however, the variation in hardness was less

  4. Dry Bag Isostatic Pressing for Improved Green Strength of Nuclear Fuel Pellets

    SciTech Connect

    G. W. Egeland; L. D. Zuck; W. R. Cannon; P. A. Lessing; P. G. Medvedev

    2010-11-01

    Dry bag isostatic pressing is proposed for mass production of nuclear fuel pellets. Dry bag isostatically pressed rods of a fuel surrogate (95% CeO2-5% HfO2) 200 mm long by 8 mm diameter were cut into pellets using a wire saw. Four different binder and two different CeO2 powder sources were investigated. The strength of the isostatically pressed pellets for all binder systems measured by diametral compression was about 50% higher than pellets produced by uniaxial dry pressing at the same pressure. It was proposed that the less uniform density of uniaxially pressed pellets accounted for the lower strength. The strength of pellets containing CeO2 powder with significantly higher moisture content was five times higher than pellets containing CeO2 powder with a low moisture content. Capillary pressure of the moisture was thought to supply the added binding strength.

  5. Microstructure of reaction-bonded silicon nitride consolidated by isostatic hot-pressing

    NASA Technical Reports Server (NTRS)

    Mieskowski, D. M.; Sanders, W. A.

    1985-01-01

    A microstructural examination and chemical analysis are conducted for reaction-bonded Si3N4 specimens that were isostatically hot pressed at 1850, 1950, and 2050 C. The present observations indicate that the previously reported increase in the 1200 C bend strength of reaction-bonded Si3N4, after pressing at 2050 C exclusively, is due to the relative oxygen levels of the isostatically hot pressed specimens; calculations show that an SiO2 content of less than about 2.2 vol pct is needed to yield the 1200 C strength increase.

  6. Manufacturing near dense metal parts via indirect selective laser sintering combined with isostatic pressing

    NASA Astrophysics Data System (ADS)

    Liu, J. H.; Shi, Y. S.; Lu, Z. L.; Huang, S. H.

    2007-11-01

    To fabricate metal parts via indirect selective laser sintering (SLS), isostatic pressing technology, including hot isostatic pressing (HIP) and cold isostatic pressing (CIP), are exploited to reform SLS green parts and make them near dense. The processes of SLS/HIP and SLS/CIP/HIP technologies are investigated respectively and the densification of AISI304 stainless steel specimens is mainly discussed. It is indicated that green parts made by indirect SLS can be pressed into near dense parts with the relative densities of 67.3% and more than 80% in SLS/HIP and SLS/CIP/HIP routes, respectively, and their densities rise if much higher CIP pressure is employed. Compared with SLS/HIP, SLS/CIP/HIP technology is regarded as a better method to manufactured dense parts, and it enlarges the application domain of indirect SLS simultaneously.

  7. High density crystalline boron prepared by hot isostatic pressing in refractory metal containers

    DOEpatents

    Hoenig, C.L.

    1993-08-31

    Boron powder is hot isostatically pressed in a refractory metal container to produce a solid boron monolith with a bulk density at least 2.22 g/cc and up to or greater than 2.34 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed or chemical vapor deposited onto a powder compact. Hot isostatic pressing at 1,800 C and 30 PSI (206.8 MPa) argon pressure for four hours produces a bulk density of 2.34 g/cc. Complex shapes can be made.

  8. High density-high purity graphite prepared by hot isostatic pressing in refractory metal containers

    DOEpatents

    Hoenig, C.L.

    1994-08-09

    Porous graphite in solid form is hot isostatically pressed in a refractory metal container to produce a solid graphite monolith with a bulk density greater than or equal to 2.10 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed, chemically vapor deposited, or coated by some other suitable means onto graphite. Hot isostatic pressing at 2,200 C and 30 KSI (206.8 MPa) argon pressure for two hours produces a bulk density of 2.10 g/cc. Complex shapes can be made. 1 fig.

  9. High density crystalline boron prepared by hot isostatic pressing in refractory metal containers

    DOEpatents

    Hoenig, Clarence L.

    1993-01-01

    Boron powder is hot isostatically pressed in a refractory metal container to produce a solid boron monolith with a bulk density at least 2.22 g/cc and up to or greater than 2.34 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed or chemical vapor deposited onto a powder compact. Hot isostatic pressing at 1800.degree. C. and 30 KSI (206.8 MPa) argon pressure for four hours produces a bulk density of 2.34 g/cc. Complex shapes can be made.

  10. High density-high purity graphite prepared by hot isostatic pressing in refractory metal containers

    DOEpatents

    Hoenig, Clarence L.

    1994-01-01

    Porous graphite in solid form is hot isostatically pressed in a refractory metal container to produce a solid graphite monolith with a bulk density greater than or equal to 2.10 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed, chemically vapor deposited, or coated by some other suitable means onto graphite. Hot isostatic pressing at 2200.degree. C. and 30 KSI (206.8 MPa) argon pressure for two hours produces a bulk density of 2.10 g/cc. Complex shapes can be made.

  11. Preparation of SiC-Based Composites by Cold Isostatic Press

    NASA Astrophysics Data System (ADS)

    Harun, M. B.; Halim, M. H.; Yazid, H.; Selamat, Z.; Sattar, M. S.; Jali, M.

    2010-03-01

    The effect of polyvinyl alcohol binder on green strength of isostatic pressed silicon carbide was studied. A lab-top spray dryer was used to coat mixed powders with the binder. The resultant powders were pressed in a steel die to obtain pre-mold at the compaction pressures of 32, 63.5, 127, 190, 254 and 317 MPa. The pre-molds were pressed using a cold isostatic press at 276 MPa to produce the green compact specimens. The porosities and compression stress of the green compact specimens produced from laboratory powder were compared with compacted specimens produced with commercial powder. Density porosimetry and universal testing machine were used to determine porosity and compression stress; respectively. The morphology and fracture surface of the green compact specimens were observed under optical and electron microscopes.

  12. High density hexagonal boron nitride prepared by hot isostatic pressing in refractory metal containers

    DOEpatents

    Hoenig, Clarence L.

    1992-01-01

    Boron nitride powder with less than or equal to the oxygen content of starting powder (down to 0.5% or less) is hot isostatically pressed in a refractory metal container to produce hexagonal boron nitride with a bulk density greater than 2.0 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed or chemical vapor deposited onto a powder compact. Hot isostatic pressing at 1800.degree. C. and 30 KSI (206.8 MPa) argon pressure for four hours produces a bulk density of 2.21 g/cc. Complex shapes can be made.

  13. Strength of hot isostatically pressed and sintered reaction bonded silicon nitrides containing Y2O3

    NASA Technical Reports Server (NTRS)

    Sanders, William A.; Mieskowski, Diane M.

    1989-01-01

    The hot isostatic pressing of reaction bonded Si3N4 containing Y2O3 produced specimens with greater room temperature strengths than those by high pressure nitrogen sintering of the same material. Average room temperature bend strengths for hot isostatically pressed reaction bonded silicon nitride and high pressure nitrogen sintered reaction bonded silicon nitride were 767 and 670 MPa, respectively. Values of 472 and 495 MPa were observed at 1370 C. For specimens of similar but lower Y2O3 content produced from Si3N4 powder using the same high pressure nitrogen sintering conditions, the room temperature strength was 664 MPa and the 1370 C strength was 402 MPa. The greater strengths of the reaction bonded silicon nitride materials in comparison to the sintered silicon nitride powder material are attributed to the combined effect of processing method and higher Y2O3 content.

  14. High density hexagonal boron nitride prepared by hot isostatic pressing in refractory metal containers

    SciTech Connect

    Hoenig, C.L.

    1990-12-31

    Boron nitride powder with less than or equal to the oxygen content of starting powder (down to 0.5% or less) is hot isostatically pressed in a refractory metal container to produce hexagonal boron nitride with a bulk density greater than 2.0 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a cansister or alternatively plasma sprayed or chemical vapor deposited onto a powder compact. Hot isostatic pressing at 1800{degrees}C and 30 KSI (206.8 MPa) argon pressure for four hours produces a bulk density of 2.21 g/cc. Complex shapes can be made.

  15. Improving the properties of cryomilled light alloys Using Spark plasma Sintering and hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Melnyk, Christopher; Grant, David; Keener, Steven G.; Gansert, Robert V.; Schroeder, Steven

    2011-02-01

    Ultrafine grained materials consolidated using spark plasma sintering and hot isostatic pressing show great potential for applications in aerospace, energy, and a vast range of other industries. The Hall-Petch relationship cites the strengthening of materials by reducing the average crystallite (grain) size. A study is proposed to investigate the increase in mechanical properties provided by fine-grained, near-nano- and nano-crystalline powders produced from cryomilling and consolidation using spark plasma sintering (SPS) and hot isostatic pressing (HIPing). Initial testing indicates an increase in hardness and shear in commercially pure aluminum by 2-3 times from use of fine-grained, near-nano-, nano-crystalline materials. Cryomilled powders and consolidated forms of these powders will be examined using field emission scanning electron microscopy. Macrohardness, microhardness, tensile testing and shear testing will be performed to examine the mechanical properties.

  16. Microstructural behavior of interfaces in hot isostatically pressed, dual alloy combinations

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1981-01-01

    Combinations of the nickel-base superalloys MERL 76 and low carbon Astroloy, Rene 95 and low carbon Astroloy, Rene 95 and NASA-TRW-VIA were consolidated from prealloyed powders by hot isostatic pressing. These combinations were exposed to 870 C for 1500 hours, and in a gradient furnance to temperatures up to incipient melting and subjected to microstructural examinations. The only phases found at the interfaces were those which were also present in the component alloys.

  17. Creep of metal-type organic compounds. 4: Application to hot isostatic pressing

    SciTech Connect

    Davies, G.C.; Jones, D.R.H.

    1997-02-01

    Hot isostatic pressing (HIP) experiments using the metal analogue materials camphene and succinonitrile are described. Data obtained previously from uniaxial creep experiments are used in densification rate equations for HIP taken from the literature, and the predicted densification behavior is compared with experimental data. The HIP equations are then modified to include two different representations of the friction stress arising from a dispersed phase of fine, hard particles. In each case the modified theory adequately describes the experimental data.

  18. Doping transition metal ions into laser host crystals by hot isostatic pressing (HIP) (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Barnes, Jacob O.; Stites, Ronald W.; Cook, Gary; McDaniel, Sean; Krein, Douglas M.; Guha, Shekhar; Goldsmith, John

    2017-05-01

    This paper describes using a hot isostatic pressing (HIP) to improve II-VI crystal characteristics and diffuse metal ions into laser host crystals. Thin layers of metal are sputtered onto the surface of zinc selenide and zinc sulfide crystals prior to being HIP treated. The pre and post treatment optical properties for these materials are measured using various methods and at a variety of dopant concentrations.

  19. Processing of surrogate nuclear fuel pellets for better dimensional control with dry bag isostatic pressing

    SciTech Connect

    Hoggan, Rita E.; Zuck, Larry D.; Cannon, W. Roger; Lessing, Paul A.

    2016-05-26

    A study of improved methods of processing fuel pellets was undertaken using ceria and zirconia/yttria/alumina as surrogates. Through proper granulation and vertical vibration (tapping) of the parts bag prior to dry bag isostatic pressing (DBIP), reproducibility of diameter profiles among multiple pellets of ceria was improved by almost an order of magnitude. Reproducibility of sintered pellets was sufficiently good to possibly avoid grinding. Deviation from the mean diameter along the length of multiple pellets, as well as, deviation from roundness, decreased after sintering. This is not generally observed with dry pressed pellets. Thus it is possible to machine to tolerance before sintering if grinding is necessary.

  20. Processing of surrogate nuclear fuel pellets for better dimensional control with dry bag isostatic pressing

    SciTech Connect

    Hoggan, Rita E.; Zuck, Larry D.; Cannon, W. Roger; Lessing, Paul A.

    2016-12-01

    A study of improved methods of processing fuel pellets was undertaken using ceria and zirconia/yttria/alumina as surrogates. Through proper granulation and vertical vibration (tapping) of the parts bag prior to dry bag isostatic pressing (DBIP), reproducibility of diameter profiles among multiple pellets of ceria was improved by almost an order of magnitude. Reproducibility of sintered pellets was sufficiently good to possibly avoid grinding. Deviation from the mean diameter along the length of multiple pellets, as well as, deviation from roundness, decreased after sintering. This is not generally observed with dry pressed pellets. Thus it is possible to machine to tolerance before sintering if grinding is necessary.

  1. Hot Isostatic Press Manufacturing Process Development for Fabrication of RERTR Monolithic Fuel Plates

    SciTech Connect

    Crapps, Justin M.; Clarke, Kester D.; Katz, Joel D.; Alexander, David J.; Aikin, Beverly; Vargas, Victor D.; Montalvo, Joel D.; Dombrowski, David E.; Mihaila, Bogdan

    2012-06-06

    We use experimentation and finite element modeling to study a Hot Isostatic Press (HIP) manufacturing process for U-10Mo Monolithic Fuel Plates. Finite element simulations are used to identify the material properties affecting the process and improve the process geometry. Accounting for the high temperature material properties and plasticity is important to obtain qualitative agreement between model and experimental results. The model allows us to improve the process geometry and provide guidance on selection of material and finish conditions for the process strongbacks. We conclude that the HIP can must be fully filled to provide uniform normal stress across the bonding interface.

  2. Low-temperature Mechanical Properties of Bulk MgB2 Fabricated by Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Murakami, A.; Teshima, H.; Naito, T.; Fujishiro, H.; Kudo, T.; Iwamoto, A.

    Mechanical properties ina MgB2superconducting bulk sample,whose packing ratio is 92%,fabricated by hot isostatic pressing (HIP)areevaluated at 77 K through bending tests.The fracture strength at 77 K is higher than at room temperature. From the bending test result at 77 K, the fracture strength of ideal bulk MgB2,whose packing ratio is 100%,is estimated. The fracture strength at very low temperature of the HIP bulk MgB2is also estimated from the bending test results at 77 K and room temperature.

  3. Microstructures and mechanical properties of hot isostatically pressed powder metallurgy Alloy APK-1

    NASA Astrophysics Data System (ADS)

    Prakash, T. L.; Chari, Y. N.; Rao, E. S. Bhagiradha; Thamburaj, R.

    1983-03-01

    The influence of Hot Isostatic Pressing (HIP) and heat treatment parameters on the microstructure and mechanical properties of powder metallurgy alloy APK-1 (a low carbon modification of Astroloy) has been investigated. Poor mechanical properties result if carbide networks are present along the prior particle boundaries (PPBs). These networks which form during powder consolidation can be avoided by manipulating HIP parameters. Heat treatments which produce a large volume fraction of fine γ’ make this alloy susceptible to environment-assisted tensile embrittlement around 760 °C.

  4. Evaluation of Hot Isostatic Pressing Parameters on the Optical and Ballistic Properties of Spinel for Transparent Armor

    DTIC Science & Technology

    2006-11-01

    pressing process that is driving the continued interest. Previous work also has identified that hot-pressing followed by hot isostatic pressing...HIPing) is the most promising method for processing transparent spinel4,5. Previous work compared hot-pressing and sintering; the HIP conditions...LITHCO, Bessemer , NC) by shaking with a TURBULA mixer (Glen Mills, Inc., Clifton, NJ) for 60 minutes in a high density polyethylene container. The

  5. Hot isostatic pressing (HIP) of powder mixtures and composites: Packing, densification, and microstructural effects

    SciTech Connect

    Li, E.K.H.; Funkenbusch, P.D. . Department of Mechanical Engineering)

    1993-06-01

    Hot isostatic pressing (HIP) of powder mixtures (containing differently sized components) and of composite powders is analyzed. Recent progress, including development of a simple scheme for estimating radial distribution functions, has made modeling of these systems practical. Experimentally, powders containing bimodal or continuous size distributions are observed to hot isostatically press to a higher density tinder identical processing conditions and to show large differences in the densification rate as a function of density when compared with the monosize powders usually assumed for modeling purposes. Modeling correctly predicts these trends and suggests that they can be partially, but not entirely, attributed to initial packing density differences. Modeling also predicts increased deformation in the smaller particles within a mixture. This effect has also been observed experimentally and is associated with microstructural changes, such as preferential recrystallization of small particles. Finally, consolidation of a composite mixture containing hard, but deformable, inclusions has been modeled for comparison with existing experimental data. Modeling results match both the densification and microstructural observations reported experimentally. Densification is retarded due to contacts between the reinforcing particles which support a significant portion of the applied pressure. In addition, partitioning of deformation between soft matrix and hard inclusion powders results in increased deformation of the softer material.

  6. Hot isostatically pressed manufacture of high strength MERL 76 disk and seal shapes

    NASA Technical Reports Server (NTRS)

    Eng, R. D.; Evans, D. J.

    1982-01-01

    The feasibility of using MERL 76, an advanced high strength direct hot isostatic pressed powder metallurgy superalloy, as a full scale component in a high technology, long life, commercial turbine engine were demonstrated. The component was a JT9D first stage turbine disk. The JT9D disk rim temperature capability was increased by at least 22 C and the weight of JT9D high pressure turbine rotating components was reduced by at least 35 pounds by replacement of forged Superwaspaloy components with hot isostatic pressed (HIP) MERL 76 components. The process control plan and acceptance criteria for manufacture of MERL 76 HIP consolidated components were generated. Disk components were manufactured for spin/burst rig test, experimental engine tests, and design data generation, which established lower design properties including tensile, stress-rupture, 0.2% creep and notched (Kt = 2.5) low cycle fatigue properties, Sonntag, fatigue crack propagation, and low cycle fatigue crack threshold data. Direct HIP MERL 76, when compared to conventionally forged Superwaspaloy, is demonstrated to be superior in mechanical properties, increased rim temperature capability, reduced component weight, and reduced material cost by at least 30% based on 1980 costs.

  7. Influence of hot isostatic pressing on ZrO2-CaO dental ceramics properties.

    PubMed

    Gionea, Alin; Andronescu, Ecaterina; Voicu, Georgeta; Bleotu, Coralia; Surdu, Vasile-Adrian

    2016-08-30

    Different hot isostatic pressing conditions were used to obtain zirconia ceramics, in order to assess the influence of HIP on phase transformation, compressive strength, Young's modulus and density. First, CaO stabilized zirconia powder was synthesized through sol-gel method, using zirconium propoxide, calcium isopropoxide and 2-metoxiethanol as precursors, then HIP treatment was applied to obtain final dense ceramics. Ceramics were morphologically and structurally characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Density measurements, compressive strength and Young's modulus tests were also performed in order to evaluate the effect of HIP treatment. The zirconia powders heat treated at 500°C for 2h showed a pure cubic phase with average particle dimension about 70nm. The samples that were hot isostatic pressed presented a mixture of monoclinic-tetragonal or monoclinic-cubic phases, while for pre-sintered samples, cubic zirconia was the single crystalline form. Final dense ceramics were obtained after HIP treatment, with relative density values higher than 94%. ZrO2-CaO ceramics presented high compressive strength, with values in the range of 500-708.9MPa and elastic behavior with Young's modulus between 1739MPa and 4372MPa. Finally zirconia ceramics were tested for biocompatibility allowing the normal development of MG63 cells in vitro.

  8. Processing of surrogate nuclear fuel pellets for better dimensional control with dry bag isostatic pressing

    DOE PAGES

    Hoggan, Rita E.; Zuck, Larry D.; Cannon, W. Roger; ...

    2016-05-26

    A study of improved methods of processing fuel pellets was undertaken using ceria and zirconia/yttria/alumina as surrogates. Through proper granulation and vertical vibration (tapping) of the parts bag prior to dry bag isostatic pressing (DBIP), reproducibility of diameter profiles among multiple pellets of ceria was improved by almost an order of magnitude. Reproducibility of sintered pellets was sufficiently good to possibly avoid grinding. Deviation from the mean diameter along the length of multiple pellets, as well as, deviation from roundness, decreased after sintering. This is not generally observed with dry pressed pellets. Thus it is possible to machine to tolerancemore » before sintering if grinding is necessary.« less

  9. Expanded Analysis of Hot Isostatic Pressed Iodine-Loaded Silver-Exchanged Mordenite

    SciTech Connect

    Jubin, R. T.; Bruffey, S. H.; Patton, K. K.

    2014-09-30

    Reduced silver-exchanged mordenite (Ag0Z) is being evaluated as a potential material to control the release of radioactive iodine that is released during the reprocessing of used nuclear fuel into the plant off-gas streams. The purpose of this study was to determine if hot pressing could directly convert this iodine loaded sorbent into a waste form suitable for long-term disposition. The minimal pretreatment required for production of pressed pellets makes hot pressing a technically and economically desirable process. Initial scoping studies utilized hot uniaxial pressing (HUPing) to prepare samples of non-iodine-loaded reduced silver exchanged mordenite (Ag0Z). The resulting samples were very fragile due to the low pressure (~ 28 MPa) used. It was recommended that hot isostatic pressing (HIPing), performed at higher temperatures and pressures, be investigated. HIPing was carried out in two phases, with a third and final phase currently underway. Phase I evaluated the effects of pressure and temperature conditions on the manufacture of a pressed sample. The base material was an engineered form of silver zeolite. Six samples of Ag0Z and two samples of I-Ag0Z were pressed. It was found that HIPing produced a pressed pellet of high density. Analysis of each pressed pellet by scanning electron microscopy-energy dispersive spectrophotometry (SEM-EDS) and X-ray diffraction (XRD) demonstrated that under the conditions used for pressing, the majority of the material transforms into an amorphous structure. The only crystalline phase observed in the pressed Ag0Z material was SiO2. For the samples loaded with iodine (I-Ag0Z) iodine was present as AgI clusters at low temperatures, and transformed into AgIO4 at high temperatures. Surface mapping and EDS demonstrate segregation between silver iodide phases and silicon dioxide phases. Based on the results of the Phase I study, an expanded test matrix was developed to examine the effects of multiple source materials, compositional

  10. Manufacture of astroloy turbine disk shapes by hot isostatic pressing, volume 1

    NASA Technical Reports Server (NTRS)

    Eng, R. D.; Evans, D. J.

    1978-01-01

    The Materials in Advanced Turbine Engines project was conducted to demonstrate container technology and establish manufacturing procedures for fabricating direct Hot Isostatic Pressing (HIP) of low carbon Astroloy to ultrasonic disk shapes. The HIP processing procedures including powder manufacture and handling, container design and fabrication, and HIP consolidation techniques were established by manufacturing five HIP disks. Based upon dimensional analysis of the first three disks, container technology was refined by modifying container tooling which resulted in closer conformity of the HIP surfaces to the sonic shape. The microstructure, chemistry and mechanical properties of two HIP low carbon Astroloy disks were characterized. One disk was subjected to a ground base experimental engine test, and the results of HIP low carbon Astroloy were analyzed and compared to conventionally forged Waspaloy. The mechanical properties of direct HIP low carbon Astroloy exceeded all property goals and the objectives of reduction in material input weight and reduction in cost were achieved.

  11. Long rod penetration test of hot isostatically pressed Ti-based targets

    NASA Astrophysics Data System (ADS)

    Nesterenko, Vitali F.; Indrakanti, Sastry S.; Brar, Singh; Gu, YaBei

    2000-04-01

    Hot Isostatic Pressing (HIP) is one of the most efficient techniques to produce high quality materials from powders. Nevertheless there is a shortage of data on high-strain-rate behavior and penetration resistance of such materials. In this paper the results of penetration test with tungsten (93%) heavy alloy penetrators of solid and porous composite samples of Ti-6Al-4V alloy with different microstructures (Widmanstatten pattern and equiaxed) are presented. Penetration depth for HIPed materials is smaller than in baseline samples of Ti-6Al-4V alloy (forged rod MIL-T-9047G). Composite materials with alumina rods and tubes filled with B4C powders demonstrated a new features of penetration: projectile deflection with self sealing of hole and forced shear localization caused by tubes fracture. The results demonstrate the applicability of HIPing for Ti-based armor materials.

  12. Evaluation of hot isostatic pressing for joining of fusion reactor structural components

    NASA Astrophysics Data System (ADS)

    Ivanov, A. D.; Sato, S.; Le Marois, G.

    2000-12-01

    Hot isostatic pressing (HIP) is a promising technology to fabricate the blanket structure of fusion reactors. HIP joining of solid materials has been selected as a reference fabrication method for the shielding blanket/first wall of the international thermonuclear experimental reactor (ITER). On the basis of experimental results obtained in Europe, Japan and Russia, an evaluation of HIP joining for fusion reactor structural components has been carried out. The parameters of HIP fabrication for copper alloys and stainless steels are given. The results of microscopic observations, X-ray microanalysis, tensile, impact toughness, fracture toughness and fatigue tests are presented. Material science criteria for an estimation of quality for joints fabricated by HIP are discussed.

  13. Manufacture of die casting dies by hot isostatic pressing. CRADA final report

    SciTech Connect

    Viswanathan, S.; Ren, W.; Luk, K.; Brucher, H.G.

    1998-09-01

    The reason for this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Doehler-Jarvis was to investigate the manufacture die-casting dies with internal water-cooling lines by hot-isostatic pressing (HIPing) of H13 tool steel powder. The use of HIPing will allow the near-net-shape manufacture of dies and the strategic placement of water-cooling lines during manufacture. The production of near-net-shape dies by HIPing involves the generation of HIPing diagrams, the design of the can that can be used for HIPing a die with complex details, strategic placement of water-cooling lines in the die, computer modeling to predict movement of the water lines during HIPing, and the development of strategies for placing water lines in the appropriate locations. The results presented include a literature review, particle analysis and characterization of H13 tool steel powder, and modeling of the HIPing process.

  14. Microstructure and Phase Composition of Cold Isostatically Pressed and Pressureless Sintered Silicon Nitride.

    PubMed

    Lukianova, O A; Krasilnikov, V V; Parkhomenko, A A; Sirota, V V

    2016-12-01

    The microstructure and physical properties of new Y2O3 and Al2O3 oxide-doped silicon nitride ceramics fabricated by cold isostatic pressing and free sintering were investigated. The phase composition of produced material was also studied by X-ray diffraction at room and elevated temperature. The fabricated ceramics featured a microstructure of Si5AlON7 grains with a fine-grained α-Si3N4 with a small amount of Y2SiAlON5. Described ceramics is attractive for many high-temperature structural applications due to beneficial combination of fine-grained structure with improved mechanical properties and small weight loss.

  15. Friction welding method of hot isostatic press can closure for the ICPP calcine immobilization program

    SciTech Connect

    Berry, S.M.; Reed, T.R.; Swainston, R.C

    1993-09-01

    An investigation of various closure techniques was performed in an effort to meet requirements for closure of evacuated waste cans to be used at Westinghouse Idaho Nuclear Company`s Idaho Chemical Processing Plant. Although other sealing techniques are available, welding was considered to be the best for sealing the cans. For various reasons. techniques other than welding are not suitable for cans that are subject to the Hot Isostatic Press (HIP) process. For example. elastomeric seals. solders. and brazing would,not withstand the temperature associated (approximately 1000 degrees centigrade) with the HIP process. Mechanical joining techniques such as threading, crimping, and swaging could result in the joint opening as the can wall is deformed during HIP process. Unlike the above joint methods, welding results in physical joining of the lid or plug to the can itself, thus the wall would have to be ruptured before leakage would occur. This document investigates welding techniques for application to the can closure.

  16. Yb:Y2O3 transparent ceramics processed with hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Ma, Jie; Zhang, Jian; Liu, Peng; Luo, Dewei; Yin, Danlei; Tang, Dingyuan; Kong, Ling Bing

    2017-09-01

    Highly transparent 5 at.% Yb:Y2O3 ceramics were fabricated by using a combination method of vacuum sintering and hot isostatic pressing (HIP). Co-precipitated Yb:Y2O3 powders, with 1 at.% ZrO2 as the sintering aid, were used as the starting material. The Yb:Y2O3 ceramics, vacuum sintered at 1700 °C for 2 h and HIPed at 1775 °C for 4 h, exhibited small grain size of 1.9 μm and highly dense microstructure. In-line optical transmittance of the ceramics reached 83.4% and 78.9% at 2000 and 600 nm, respectively. As the ceramic slab was pumped by a fiber-coupled laser diode at about 940 nm, a maximum output power of 0.77 W at 1076 nm was achieved, with a corresponding slope efficiency of 10.6%.

  17. Processing of surrogate nuclear fuel pellets for better dimensional control with dry bag isostatic pressing

    NASA Astrophysics Data System (ADS)

    Hoggan, Rita E.; Zuck, Larry D.; Cannon, W. Roger; Lessing, Paul A.

    2016-12-01

    A study of improved methods of processing fuel pellets was undertaken using ceria and zirconia/yttria/alumina as surrogates. Through proper granulation, elimination of fines and vertical vibration (tapping) of the parts bag prior to dry bag isostatic pressing (DBIP), reproducibility of diameter profiles among multiple pellets of ceria was improved by almost an order of magnitude. Reproducibility of sintered pellets in these studies was sufficient to allow pellets to be introduced into the cladding with a gap between the pellet and cladding on the order of 50 μm to 100 μm but not a uniform gap with tolerance of ±12 μm as is currently required. Deviation from the mean diameter along the length of multiple pellets, and deviation from roundness, decreased after sintering. This is not generally observed with dry pressed pellets. Sintered shrinkage was uniform to ±0.05% and thus, as an alternative, pellets may be machined to tolerance before sintering, thus avoiding the waste associated with post-sinter grinding.

  18. Magnetic and magneto elastic properties of cobalt ferrite ceramic compacted through cold isostatic pressing

    SciTech Connect

    Indla, Srinivas; Das, Dibakar; Chelvane, Arout

    2016-05-06

    Nano crystalline CoFe{sub 2}O{sub 4} powder was prepared by combustion synthesis method. As synthesized powder was calcined at an appropriate condition to remove the impurities and to promote phase formation. Phase pure CoFe{sub 2}O{sub 4} powder was pressed into cylindrical rod at an applied pressure of 200 MPa using a cold isostatic pressing. Sintering of the green compact at 1350°c for 12 hrs resulted in sintered cylindrical rod with ~85% of the theoretical density. Single phase cubic spinel structure was observed in the powder x-ray diffraction pattern of the sintered pellet. Scanning electron micrographs (SEM) of the as sintered pellet revealed the microstructure to be composed of ferrite grains of average size ~4 µm. Saturation magnetization of 72 emu/g and coercivity of 355 Oe were observed for cobalt ferrite sample. The magnetostriction was measured on a circular disc (12 mm diameter and 12 mm length) with the strain gauge (350 Ω) mounted on the flat surface of the circular disc. Magnetostriciton of 180 ppm and strain derivative of 1 × 10{sup −9} m/A were observed for the sintered CoFe{sub 2}O{sub 4} sample.

  19. Grain-boundary cavitation and bloating of isostatically hot-pressed magnesia-partially-stabilized zirconia on air annealing

    SciTech Connect

    Hogg, C.L.; Stringer, R.K.; Swain, M.V.

    1986-03-01

    Commercially sintered magnesia-partially-stabilized zirconia was densified to near theoretical density by isostatic hot-pressing at 200 MPa and 1700/sup 0/C in argon. Subsequent air annealing above 1100/sup 0/C resulted in bloating of the material due to grain-boundary cavitation. Mass spectrometry of crushed samples detected the evolution of CO/sub 2/ and possibly CO on annealing; the hot-pressed material showed a sudden gas evolution above 1400/sup 0/C. Preliminary Auger and ESCA analysis identified the presence of carbon as graphite and an undefined carbide in both the sintered and the hot-pressed material.

  20. High cycle fatigue and fracture behaviour of a hot isostatically pressed nickel-based superalloy

    NASA Astrophysics Data System (ADS)

    Qiu, Chunlei; Wu, Xinhua

    2014-01-01

    Powder of a nickel-based superalloy, RR1000, has been hot isostatically pressed (HIPped) at a supersolvus temperature and post-HIP heat treated to produce different microstructures. Microstructures were investigated using a scanning electron microscope together with an energy dispersive X-ray spectrometer and a wave-length dispersive X-ray spectrometer. High cycle four-point bending fatigue and tension-tension fatigue tests have been performed on the fabricated samples. It was found that HIPped and aged samples showed the best four-point bending fatigue limit while HIPped and solution-treated and aged samples had the lowest fatigue limit. The four-point bending fatigue crack initiations all occurred from the sample surfaces either at the sites of inclusion clusters or by cleavage through large grains on the surfaces. The tension-tension fatigue crack initiation occurred mainly due to large hafnia inclusion clusters, with lower fatigue lives for samples where inclusions were closer to the surface. Crack initiation at the compact Al2O3 inclusion cluster led to a much higher fatigue life than found when cracks were initiated by large hafnia inclusion clusters. The tension-tension fatigue limits were shown to decrease with increased testing temperature (from room temperature to 700 °C).

  1. Effect of reduced cobalt contents on hot isostatically pressed powder metallurgy U-700 alloys

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1982-01-01

    The effect of reducing the cobalt content of prealloyed powders of UDIMET 700 (U-700) alloys to 12.7, 8.6, 4.3, and 0% was examined. The powders were hot isostatically pressed into billets, which were given heat treatments appropriate for turbine disks, namely partial solutioning at temperatures below the gamma prime solvus and four step aging treatments. Chemical analyses, metallographic examinations, and X-ray diffraction measurements were performed on the materials. Minor effects on gamma prime content and on room temperature and 650 C tensile properties were observed. Creep rupture lives at 650 C reached a maximum at the 8.4% concentration, while at 760 C a maximum in life was reached at the 4.3% cobalt level. Minimum creep rates increased with decreasing cobalt content at both test temperatures. Extended exposures at 760 and 815 C resulted in decreased tensile strengths and rupture lives for all alloys. Evidence of sigma phase formation was also found.

  2. The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1985-01-01

    Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

  3. Hot isostatic pressing of silicon nitride with boron nitride, boron carbide, and carbon additions

    NASA Technical Reports Server (NTRS)

    Mieskowski, Diane M.; Sanders, William A.

    1989-01-01

    Si3N4 test bars containing additions of BN, B4C, and C, were hot isostatically pressed in Ta cladding at 1900 and 2050 C to 98.9 percent to 99.5 percent theoretical density. Room-temperature strength data on specimens containing 2 wt pct BN and 0.5 wt pct C were comparable to data obtained for Si3N4 sintered with Y2O3, Y2O3 and Al2O3, or ZrO2. The 1370 C strengths were less than those obtained for additions of Y2O3 or ZrO2 but greater than those obtained from a combination of Y2O3 and Al2O3. SEM fractography indicated that, as with other types of Si3N4, room-temperature strength was controlled by processing flaws. The decrease in strength at 1370 C was typical of Si3N4 having an amorphous grain-boundary phase. The primary advantage of nonoxide additions appears to be in facilitating specimen removal from the Ta cladding.

  4. The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1985-01-01

    Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

  5. Effect of reduced cobalt contents on hot isostatically pressed powder metallurgy U-700 alloys

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1982-01-01

    The effect of reducing the cobalt content of prealloyed powders of UDIMET 700 (U-700) alloys to 12.7, 8.6, 4.3, and 0% was examined. The powders were hot isostatically pressed into billets, which were given heat treatments appropriate for turbine disks, namely partial solutioning at temperatures below the gamma prime solvus and four step aging treatments. Chemical analyses, metallographic examinations, and X-ray diffraction measurements were performed on the materials. Minor effects on gamma prime content and on room temperature and 650 C tensile properties were observed. Creep rupture lives at 650 C reached a maximum at the 8.4% concentration, while at 760 C a maximum in life was reached at the 4.3% cobalt level. Minimum creep rates increased with decreasing cobalt content at both test temperatures. Extended exposures at 760 and 815 C resulted in decreased tensile strengths and rupture lives for all alloys. Evidence of sigma phase formation was also found.

  6. The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

    NASA Astrophysics Data System (ADS)

    Harf, Fredric H.

    1985-06-01

    Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of γ' particles in a γ matrix. The higher cobalt-content alloys contained larger amounts of the finest γ' particles, and had the lowest γ-γ' lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650°C, the rupture lives at 650 and 760°C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the γ' particle size distribution and the γ-γ' mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

  7. High temperature mechanical performance of a hot isostatically pressed silicon nitride

    SciTech Connect

    Wereszczak, A.A.; Ferber, M.K.; Jenkins, M.G.; Lin, C.K.J.

    1996-01-01

    Silicon nitride ceramics are an attractive material of choice for designers and manufacturers of advanced gas turbine engine components for many reasons. These materials typically have potentially high temperatures of usefulness (up to 1400{degrees}C), are chemically inert, have a relatively low specific gravity (important for inertial effects), and are good thermal conductors (i.e., resistant to thermal shock). In order for manufacturers to take advantage of these inherent properties of silicon nitride, the high-temperature mechanical performance of the material must first be characterized. The mechanical response of silicon nitride to static, dynamic, and cyclic conditions at elevated temperatures, along with reliable and representative data, is critical information that gas turbine engine designers and manufacturers require for the confident insertion of silicon nitride components into gas turbine engines. This final report describes the high-temperature mechanical characterization and analyses that were conducted on a candidate structural silicon nitride ceramic. The high-temperature strength, static fatigue (creep rupture), and dynamic and cyclic fatigue performance were characterized. The efforts put forth were part of Work Breakdown Structure Subelement 3.2.1, {open_quotes}Rotor Data Base Generation.{close_quotes} PY6 is comparable to other hot isostatically pressed (HIPed) silicon nitrides currently being considered for advanced gas turbine engine applications.

  8. Hot Isostatic Pressing (HIP) Model Developments for P/M Alloy 690N{sub 2}

    SciTech Connect

    J.W. Sears; J. Xu

    2001-08-30

    Powder Metallurgy (P/M) Alloy 690N{sub 2}, the P/M derivative of Inconel 690 (IN 690), has been shown to have a higher elevated temperature yield strength and superior stress corrosion cracking (SCC) resistance than IN 690. The property improvements seen in P/M Alloy 690N{sub 2} are due to interstitial nitrogen strengthening and precipitation hardening resulting from the formation of fine titanium/chromium--carbo-nitrides. The application of P/M Alloy 690N{sub 2} has had limited use, because of the high costs involved in producing wrought products from powder. Hot Isostatic Pressing (HIP) modeling to produce near net shapes should provide a more economical route for exploiting the benefits of Alloy 690N{sub 2}. The efforts involved in developing and verifying the P/M Alloy 690N{sub 2} HIP model are disclosed. Key to the deployment of HIP modeling is the development of the method to fabricate HIP powder containers via laser powder deposition.

  9. The effect of hot isostatic pressing on crack initiation, fatigue, and mechanical properties of two cast aluminum alloys

    NASA Astrophysics Data System (ADS)

    Rich, T. P.; Orbison, J. G.; Duncan, R. S.; Olivero, P. G.; Peterec, R. H.

    1999-06-01

    This article presents the results of an experimental materials testing program on the effect of hot isostatic pressing (HIP) on the crack initiation, fatigue, and mechanical properties of two cast aluminum alloys: AMS 4220 and 4225. These alloys are often used in castings for high temperature applications. Standard tensile and instrumented Charpy impact tests were performed at room and elevated temperatures. The resulting data quantify improvements in ultimate tensile strength, ductility, and Charpy impact toughness from the HIP process while indicating little change in yield strength for both alloys. In addition standard fracture mechanics fatigue tests along with a set of unique fatigue crack initiation tests were performed on the alloys. Hot isostatic pressing was shown to produce a significant increase in cycles to crack initiation for AMS 4225, while no change was evident in traditional da/dN fatigue crack growth. The data permits comparisons of the two alloys both with and without the HIP process.

  10. Microstructure and mechanical properties of hip-consolidated Rene 95 powders. [hot-isostatic pressed nickel-based powder metal

    NASA Technical Reports Server (NTRS)

    Shimanuki, Y.; Nishino, Y.; Masui, M.; Doi, H.

    1980-01-01

    The effects of heat-treatments on the microstructure of P/M Rene 95 (a nickel-based powder metal), consolidated by the hot-isostatic pressing (HIP), were examined. The microstructure of as-HIP'd specimen was characterized by highly serrated grain boundaries. Mechanical tests and microstructural observations reveal that the serrated grain boundaries improved ductility at both room and elevated temperatures by retarding crack propagation along grain boundaries.

  11. The Effectiveness of Hot Isostatic Pressing for Closing Porosity in Titanium Parts Manufactured by Selective Electron Beam Melting

    NASA Astrophysics Data System (ADS)

    Tammas-Williams, Samuel; Withers, Philip J.; Todd, Iain; Prangnell, Philip B.

    2016-05-01

    Ti-6Al-4V parts, produced by selective electron beam melting additive manufacturing, have been studied by X-ray computed tomography (XCT) to track pore closure during a standard hot isostatic pressing (HIPing) cycle. Comparison of repeated XCT scans before and after HIPing, on worst-case samples with different geometries, confirmed that all internal porosity was shrunk to below the resolution limit of the equipment used (~5 µm) following the HIPing cycle, apart from defects with surface connected ligaments.

  12. Densification of molybdenum and molybdenum alloy powders using hot isostatic pressing. Final technical report

    SciTech Connect

    Barranco, J.; Ahmad, I.; Isserow, S.; Warenchak, R.

    1985-08-01

    This study was conducted to determine a superior erosion-resistant gun-barrel liner material with improved properties at higher temperatures. Four categories of powders were examined: 1. TZM spherical containing 0.5 titanium, 0.08 zirconium, and 0.02 carbon (wt. % nominally), balance molybdenum (Mo), produced by REP (Rotating Electrode Process), PREP (Plasma Rotating Electrode Process), and PMRS (Plasma Melted and Rapidly Solidified); 2. Mo reduced 2 and 5 microns; 3. Mo-0.1% cobalt, co-reduced; 4. Mo-5 wt. % alumina (A12O3), dispersion strengthened. Hot Isostatic Pressing (HIP) densification occurred at 15-30 Ksi, 1300-1600 C, for 1.5 to 3.0 hours. The TZM REP/PREP powders (220/74 microns) were not fully densified even at 1600 C, 30 Ksi, 3 hours. Point-particle contact prevented complete void elimination. TZM PMRS powder (24.7 microns) achieved 99% of theoretical density while maintaining a small grain size (10.4 ASTM eq.) Bend deflection and fracture energies were approximately three times those for PREP powder at a bend rupture strength of about 120 Ksi. Mo reduced and Mo-0.1% Co powders showed less (or the same) ductility with increasing HIP temperatures. Fractures were intergranular with decreased bend rupture and compression strength. The Mo-5A1/sub 2/O/sub 3/ powder maintained a fine grain size (13 ASTM eq.), but with fracture energies usually less than 0.6 in.-lbs. Included are results from bending and compression testing with metallographic and fracture mode interpretation.

  13. Enhancement of the electrical characteristics of metal-free phthalocyanine films using cold isostatic pressing

    SciTech Connect

    Matsushima, Toshinori E-mail: adachi@cstf.kyushu-u.ac.jp; Adachi, Chihaya E-mail: adachi@cstf.kyushu-u.ac.jp; Esaki, Yu

    2014-12-15

    Spatial gaps between grains and other grains, substrates, or electrodes in organic electronic devices are one of the causes of the reduction in the electrical characteristics. In this study, we demonstrate that cold isostatic pressing (CIP) is an effective method to crush the gaps and enhance the electrical characteristics. CIP of metal-free phthalocyanine (H{sub 2}PC) films induced a decrease in the film thickness by 34%–40% because of the gap crush. The connection of smaller grains into a larger grain and planarization of the film surface were also observed in the CIP film. The crystal axes of the H{sub 2}PC crystallites were rearranged from the a-axis to the c-axis of the α-phase crystal structure in a direction perpendicular to the substrate by CIP, indicating favorable hole injection and transport in this direction because of a better overlap of π orbitals. Thermally stimulated current measurements showed that deep hole traps disappeared and the total hole-trap density decreased after CIP. These CIP-induced changes of the film thicknesses, crystal axes and the hole traps lead to a marked increase in the hole mobility of the H{sub 2}PC films from 2.0 × 10{sup −7} to 4.0 × 10{sup −4} cm{sup 2}/V s by 2000 times in the perpendicular direction. We believe that these findings are important for unveiling the underlying carrier injection and transport mechanisms of organic films and for enhancing the performance of future organic electronic devices.

  14. Enhancement of Fe diffusion in ZnSe/S laser crystals under hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Gafarov, Ozarfar; Martinez, Alan; Fedorov, Vladimir; Mirov, Sergey

    2017-02-01

    Many organic molecules have strong and narrow absorption features in the middle Infrared (mid-IR) spectral range. The ability to directly probe absorption features of molecules enables numerous mid-IR applications in non-invasive medical diagnosis, industrial processing and process control, environmental monitoring, etc. Thus, there is a strong demand for lasers operating in mid-IR spectral range. Transition metal (TM) doped II-VI semiconductors such as Fe/Cr:ZnSe/S are the material of choice for fabrication of mid-IR gain media due to favorable combination of properties: a four level energy structure, absence of excited state absorption , broad mid-IR vibronic absorption and emission bands. Despite the significant progress in post-growth thermal diffusion technology of TM:II-VI fabrication there are still some difficulties associated with diffusion of certain TM's in these materials. In this work we address the issue of poor diffusion of Fe in ZnSe/S polycrystals. It is well known that with the temperature increase the diffusion rate of impurity also increases. However, simple application of high temperatures during the diffusion process is problematic for ZnSe/S crystals due to their strong sublimation. The sublimation processes can be suppressed by application of high pressures. Hot isostatic pressing was utilized as the means for simultaneous application of high temperatures (1300°C) and high pressures (1000atm, 3000atm). It was determined that diffusion coefficient of Fe was improved 13 and 14 fold in ZnSe and ZnS, respectively, as compared to the standard diffusion at 950°C. The difference in diffusion coefficients can be due to strong increase in the grain size of polycrystals.

  15. CuCrZr alloy microstructure and mechanical properties after hot isostatic pressing bonding cycles

    NASA Astrophysics Data System (ADS)

    Frayssines, P.-E.; Gentzbittel, J.-M.; Guilloud, A.; Bucci, P.; Soreau, T.; Francois, N.; Primaux, F.; Heikkinen, S.; Zacchia, F.; Eaton, R.; Barabash, V.; Mitteau, R.

    2014-04-01

    ITER first wall (FW) panels are a layered structure made of the three following materials: 316L(N) austenitic stainless steel, CuCrZr alloy and beryllium. Two hot isostatic pressing (HIP) cycles are included in the reference fabrication route to bond these materials together for the normal heat flux design supplied by the European Union (EU). This reference fabrication route ensures sufficiently good mechanical properties for the materials and joints, which fulfil the ITER mechanical specifications, but often results in a coarse grain size for the CuCrZr alloy, which is not favourable, especially, for the thermal creep properties of the FW panels. To limit the abnormal grain growth of CuCrZr and make the ITER FW fabrication route more reliable, a study began in 2010 in the EU in the frame of an ITER task agreement. Two material fabrication approaches have been investigated. The first one was dedicated to the fabrication of solid CuCrZr alloy in close collaboration with an industrial copper alloys manufacturer. The second approach investigated was the manufacturing of CuCrZr alloy using the powder metallurgy (PM) route and HIP consolidation. This paper presents the main mechanical and microstructural results associated with the two CuCrZr approaches mentioned above. The mechanical properties of solid CuCrZr, PM CuCrZr and joints (solid CuCrZr/solid CuCrZr and solid CuCrZr/316L(N) and PM CuCrZr/316L(N)) are also presented.

  16. Characterization of hot isostatically pressed Bi-Sr-Ca-Cu-O as a function of consolidation variables

    SciTech Connect

    Goretta, K.C.; Miller, D.J.; Poeppel, R.B. ); Nash, A.S. )

    1991-11-01

    Fully dense, bulk Bi{sub 2}Sr{sub 1.7}CaCu{sub 2}O{sub x} (2212) superconductor pellets were made by hot isostatic pressing in an inert atmosphere. Electron microscopy revealed that rotation and bending of the platelike 2212 grains were responsible for much of the densification. Under processing conditions of 825{degrees}C and 105 MPa, dense pellets were obtained in 15 min. Many dislocations, planar faults, and, perhaps, intergrowths of the Bi{sub 2}Sr{sub 2}CuO{sub x} phase were produced during pressing. The dislocations were largely present in subgrain boundaries when the pressing times were increased to 45--120 min.

  17. Effect of HIPping (Hot Isostatic Pressing) on electron beam melting Ti6Al4V parts after machining

    NASA Astrophysics Data System (ADS)

    Dolimont, Adrien; Michotte, Sebastien; Rivière-Lorphèvre, Edouard; Ducobu, François; de Formanoir, Charlotte; Godet, Stéphane; Filippi, Enrico

    2016-10-01

    The fast growing of Additive Manufacturing (AM) leads us to study the functionality of parts built by these processes. Recently, the Electron Beam Melting process and the Direct Melting Laser Sintering process are used to produce parts in the biomedical and aeronautical fields. The Ti6Al4V is largely used in these fields. This paper present an experimental study of machining Ti6Al4V alloy produced by Electron Beam Melting (EBM) before and after HIPping (Hot Isostatic Pressing). The results shows that the hipping has no significant influence on specific cutting pressure.

  18. An Assessment of the Ductile Fracture Behavior of Hot Isostatically Pressed and Forged 304L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Cooper, A. J.; Smith, R. J.; Sherry, A. H.

    2017-02-01

    Type 300 austenitic stainless steel manufactured by hot isostatic pressing (HIP) has recently been shown to exhibit subtly different fracture behavior from that of equivalent graded forged steel, whereby the oxygen remaining in the component after HIP manifests itself in the austenite matrix as nonmetallic oxide inclusions. These inclusions facilitate fracture by acting as nucleation sites for the initiation, growth, and coalescence of microvoids in the plastically deforming austenite matrix. Here, we perform analyses based on the Rice-Tracey (RT) void growth model, supported by instrumented Charpy and J-integral fracture toughness testing at ambient temperature, to characterize the degree of void growth ahead of both a V-notch and crack in 304L stainless steel. We show that the hot isostatically pressed (HIP'd) 304L steel exhibits a lower critical void growth at the onset of fracture than that observed in forged 304L steel, which ultimately results in HIP'd steel exhibiting lower fracture toughness at initiation and impact toughness. Although the reduction in toughness of HIP'd steel is not detrimental to its use, due to the steel's sufficiently high toughness, the study does indicate that HIP'd and forged 304L steel behave as subtly different materials at a microstructural level with respect to their fracture behavior.

  19. An Assessment of the Ductile Fracture Behavior of Hot Isostatically Pressed and Forged 304L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Cooper, A. J.; Smith, R. J.; Sherry, A. H.

    2017-05-01

    Type 300 austenitic stainless steel manufactured by hot isostatic pressing (HIP) has recently been shown to exhibit subtly different fracture behavior from that of equivalent graded forged steel, whereby the oxygen remaining in the component after HIP manifests itself in the austenite matrix as nonmetallic oxide inclusions. These inclusions facilitate fracture by acting as nucleation sites for the initiation, growth, and coalescence of microvoids in the plastically deforming austenite matrix. Here, we perform analyses based on the Rice-Tracey (RT) void growth model, supported by instrumented Charpy and J-integral fracture toughness testing at ambient temperature, to characterize the degree of void growth ahead of both a V-notch and crack in 304L stainless steel. We show that the hot isostatically pressed (HIP'd) 304L steel exhibits a lower critical void growth at the onset of fracture than that observed in forged 304L steel, which ultimately results in HIP'd steel exhibiting lower fracture toughness at initiation and impact toughness. Although the reduction in toughness of HIP'd steel is not detrimental to its use, due to the steel's sufficiently high toughness, the study does indicate that HIP'd and forged 304L steel behave as subtly different materials at a microstructural level with respect to their fracture behavior.

  20. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    NASA Astrophysics Data System (ADS)

    Zhao, Yanyun; Li, Chunjing; Huang, Bo; Liu, Shaojun; Huang, Qunying

    2014-12-01

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

  1. An infrared pyroelectric detector improved by cool isostatic pressing with cup-shaped PZT thick film on silicon substrate

    NASA Astrophysics Data System (ADS)

    Peng, Q. X.; Wu, C. G.; Luo, W. B.; Chen, C.; Cai, G. Q.; Sun, X. Y.; Qian, D. P.

    2013-11-01

    In this paper, we presented a new pyroelectric detector with back to back silicon cups and micro-bridge structure. The PZT thick film shaped in the front cup was directly deposited with designed pattern by electrophoresis deposition (EPD). Pt/Ti Metal film, which was fabricated by standard photolithography and lift-off technology, was sputtered to connect the top electrode and the bonding pad. The cold isostatic press (CIP) treatment could be applied to improve the pyroelectric properties of PZT thick film. The infrared (IR) properties the CIP-optimized detector were measured. The voltage responsivity (RV) was 4.5 × 102 V/W at 5.3 Hz, the specific detectivity (D*) was greater than 6.34 × 108 cm Hz1/2 W-1 (frequency > 110 Hz), and the thermal time constant was 51 ms, respectively.

  2. Microstructure and mechanical properties of hot isostatically pressed zirconia (2 mol% yttria)-reinforced tungsten disilicide composites

    SciTech Connect

    Yamaguchi, Kotaro; Yoshinaka, Masaru; Hirota, Ken; Yamaguchi, Osamu

    1995-08-01

    Dense sintered composites of ZrO{sub 2} (2 mol% Y{sub 2}O{sub 3}) and WSi{sub 2} have been fabricated by hot isostatic pressing for 2 h at 1500 C under 196 MPa. They contain a small amount of W{sub 5}Si{sub 3}; during sintering, WSi{sub 2} decomposes into W{sub 5}Si{sub 3} and amorphous Si. The ZrO{sub 2} Particles in the composites consists of only t-ZrO{sub 2}. Microstructures and mechanical properties are examined, in connection with ZrO{sub 2} content. The fracture toughness and bending strength of the composite with 40 mol% ZrO{sub 2} addition are 7.1 MPa{center_dot}m{sup 1/2} and 1,011 MPa, respectively.

  3. Experimental and Theoretical Investigations of Hot Isostatically Pressed-Produced Stainless Steel/High Alloy Tool Steel Compound Materials

    NASA Astrophysics Data System (ADS)

    Lindwall, Greta; Flyg, Jesper; Frisk, Karin; Sandberg, Odd

    2011-05-01

    Consolidation of tool steel powders and simultaneous joining to a stainless 316L steel are performed by hot isostatic pressing (HIP). Two tool steel grades are considered: a high vanadium alloyed carbon tool steel, and a high vanadium and chromium alloyed nitrogen tool steel. The boundary layer arising during diffusion bonding is in focus and, in particular, the diffusion of carbon and nitrogen over the joint. Measurements of the elemental concentration profiles and corrosion tests by the double loop-electrochemical potentiokinetic reactivation (DL-EPR) method are performed. Comparative calculations with the DICTRA software are performed and are found to be in agreement with the experimental results. It is found that the carbon tool steel grade has a more critical influence on the corrosion resistance of the stainless 316L steel in comparison to the nitrogen tool steel grade.

  4. Manufacture of low carbon astroloy turbine disk shapes by hot isostatic pressing. Volume 2, project 1

    NASA Technical Reports Server (NTRS)

    Eng, R. D.; Evans, D. J.

    1979-01-01

    The performance of a hot isotatic pressed disk installed in an experimental engine and exposed to realistic operating conditions in a 150-hour engine test and a 1000 cycle endurance test is documented. Post test analysis, based on visual, fluorescent penetrant and dimensional inspection, revealed no defects in the disk and indicated that the disk performed satisfactorily.

  5. Biomimetic evaluation of β tricalcium phosphate prepared by hot isostatic pressing.

    PubMed

    Mateescu, Mihaela; Rguitti, Emmanuelle; Ponche, Arnaud; Descamps, Michel; Anselme, Karine

    2012-01-01

    Two types of completely densified β-TCP tablets were synthesized from a stoichiometric β-TCP powder. The first ones (TCP) were conventionally sintered, while the second ones (TCP-T) were sintered and treated by hot isostatic process (HIP). The HIP produced completely densified materials with relative densities greater than 99.9% and a transparent appearance of tablets. Samples were immersed in culture medium with (CM) or without serum (NCM) in static and dynamic conditions for a biomimetic evaluation. Similarly, SaOs-2 cells were cultured on samples in a static or dynamic flow perfusion system. The results of surface transformation in absence of cells showed that the dynamic condition increased the speed of calcium phosphate precipitations compared with the static condition. The morphology of precipitates was different with nature of tablets. The immersion in CM did impede this precipitation. XPS analysis of TCP-T tablets showed the presence of hydroxyapatite (HA) precipitates after incubation in NCM while octacalcium phosphate (OCP) precipitates were formed after incubation in CM. The analysis of the response of SaOs-2 cells on surfaces showed that the two types of materials are biocompatible. However, the dynamic mode of culture stimulated the differentiation of cells. Finally, it appears that the HIP treatment of TCP produces highly densified and transparent samples that display a good in vitro biocompatibility in static and dynamic culture conditions. Moreover, an interesting result of this work is the relationship between the presence of proteins in the immersion medium and the quality of precipitates formed on hipped TCP surface.

  6. Biomimetic evaluation of β tricalcium phosphate prepared by hot isostatic pressing

    PubMed Central

    Mateescu, Mihaela; Rguitti, Emmanuelle; Ponche, Arnaud; Descamps, Michel; Anselme, Karine

    2012-01-01

    Two types of completely densified β-TCP tablets were synthesized from a stoichiometric β-TCP powder. The first ones (TCP) were conventionally sintered, while the second ones (TCP-T) were sintered and treated by hot isostatic process (HIP). The HIP produced completely densified materials with relative densities greater than 99.9% and a transparent appearance of tablets. Samples were immersed in culture medium with (CM) or without serum (NCM) in static and dynamic conditions for a biomimetic evaluation. Similarly, SaOs-2 cells were cultured on samples in a static or dynamic flow perfusion system. The results of surface transformation in absence of cells showed that the dynamic condition increased the speed of calcium phosphate precipitations compared with the static condition. The morphology of precipitates was different with nature of tablets. The immersion in CM did impede this precipitation. XPS analysis of TCP-T tablets showed the presence of hydroxyapatite (HA) precipitates after incubation in NCM while octacalcium phosphate (OCP) precipitates were formed after incubation in CM. The analysis of the response of SaOs-2 cells on surfaces showed that the two types of materials are biocompatible. However, the dynamic mode of culture stimulated the differentiation of cells. Finally, it appears that the HIP treatment of TCP produces highly densified and transparent samples that display a good in vitro biocompatibility in static and dynamic culture conditions. Moreover, an interesting result of this work is the relationship between the presence of proteins in the immersion medium and the quality of precipitates formed on hipped TCP surface. PMID:23507861

  7. Hot isostatic pressing of silicon nitride Sisub3n4 containing zircon, or zirconia and silica

    NASA Technical Reports Server (NTRS)

    Somiya, S.; Yoshimura, M.; Suzuki, T.; Nishimura, H.

    1980-01-01

    A hydrothermal synthesis apparatus with a 10 KB cylinder was used to obtain a sintered body of silicon nitride. The sintering auxiliary agents used were zircon (ZrSiO4) and a mixture of zirconia (ZrO2) and silica (SiO2). Experiments were conducted with the amounts of ZrSi04 or ArO2 and SiO2 varying over a wide range and the results compared to discover the quantity of additive which produced sintering in silicon nitride by the hot pressing method.

  8. Microstructure, Tensile Properties, and Hot-Working Characteristics of a Hot Isostatic-Pressed Powder Metallurgy Superalloy

    NASA Astrophysics Data System (ADS)

    Chang, Litao; Sun, Wenru; Cui, Yuyou; Yang, Rui

    2017-01-01

    A series of microstructure observation, tensile, and hot compression tests were conducted to investigate the variation of microstructure, tensile properties, and hot-working characteristics of a powder metallurgy (PM) superalloy with hot isostatic pressing (HIPing) temperature, to establish a basis for the parameter selection for PM superalloy preparation. The results show that the dendritic structure from the powder was not completely removed until the HIPing temperature is above the γ' solvus; γ/γ' eutectic formed when the powder particles were HIPed at 1533 K (1260 °C) or above. Prior particle boundaries (PPBs) were observed in alloys HIPed at 1513 K (1240 °C) and below; the PPB decoration is serious in alloys HIPed at 1483 K and 1513 K (1210 °C and 1240 °C), owing to melting and aggregation of the boride phase at the particle boundaries during HIPing; the PPBs were eliminated when the HIPing was done at 1533 K (1260 °C) or above. Tensile fracture mode of the alloy changes from inter-particle and transgranular mixed fracture to transgranular fracture with increasing HIPing temperature, which is in accordance with the change in precipitate distribution at the PPBs. The hot workability of alloy is poor for all combinations of HIPing/deformation conditions except for HIPing at sub-solvus temperature and deformation at low strain rates.

  9. Thermal Shock and Ablation Behavior of Tungsten Nozzle Produced by Plasma Spray Forming and Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Wang, Y. M.; Xiong, X.; Zhao, Z. W.; Xie, L.; Min, X. B.; Yan, J. H.; Xia, G. M.; Zheng, F.

    2015-08-01

    Tungsten nozzle was produced by plasma spray forming (PSF, relative density of 86 ± 2%) followed by hot isostatic pressing (HIPing, 97 ± 2%) at 2000 °C and 180 MPa for 180 min. Scanning electron microscope, x-ray diffractometer, Archimedes method, Vickers hardness, and tensile tests have been employed to study microstructure, phase composition, density, micro-hardness, and mechanical properties of the parts. Resistance of thermal shock and ablation behavior of W nozzle were investigated by hot-firing test on solid rocket motor (SRM). Comparing with PSF nozzle, less damage was observed for HIPed sample after SRM test. Linear ablation rate of nozzle made by PSF was (0.120 ± 0.048) mm/s, while that after HIPing reduced to (0.0075 ± 0.0025) mm/s. Three types of ablation mechanisms including mechanical erosion, thermophysical erosion, and thermochemical ablation took place during hot-firing test. The order of degree of ablation was nozzle throat > convergence > dilation inside W nozzle.

  10. Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying and Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Ma, L. W.; Chung, C. Y.; Tong, Y. X.; Zheng, Y. F.

    2011-07-01

    In the past decades, systematic researches have been focused on studying Ti-Nb-based SMAs by adding ternary elements, such as Mo, Sn, Zr, etc. However, only arc melting or induction melting methods, with subsequent hot or cold rolling, were used to fabricate these Ni-free SMAs. There is no work related to powder metallurgy and porous structures. This study focuses on the fabrication and characterization of porous Ti-22Nb-6Zr (at.%) shape memory alloys produced using elemental powders by means of mechanical alloying and hot isostatic pressing. It is found that the porous Ti-22Nb-6Zr alloys prepared by the HIP process exhibit a homogenous pore distribution with spherical pores, while the pores have irregular shape in the specimen prepared by conventional sintering. X-ray diffraction analysis showed that the solid solution-treated Ti-22Nb-6Zr alloy consists of both β phase and α″ martensite phase. Morphologies of martensite were observed. Finally, the porous Ti-22Nb-6Zr SMAs produced by both MA and HIP exhibit good mechanical properties, such as superior superelasticity, with maximum recoverable strain of ~3% and high compressive strength.

  11. Hot isostatic pressing-processed hydroxyapatite-coated titanium implants: light microscopic and scanning electron microscopy investigations.

    PubMed

    Wie, H; Herø, H; Solheim, T

    1998-01-01

    Hot isostatic pressing (HIP) was used in a new procedure to produce hydroxyapatite (HA) coatings on a commercially pure titanium (cpTi) substrate for osseous implantation. Eighteen HIP-processed HA-coated implants were placed in the inferior border of the mandibles in 2 Labrador retriever dogs and left submerged for 3 months. As control specimens, 12 sandblasted cpTi implants were placed in the same mandibles and, to compare the bone reaction, 2 additional plasma-sprayed HA-coated implants (Integral) were placed. Tissue reactions at the bony interfaces of the implants were studied in ground sections with the implants in situ, using ordinary, fluorescent, and polarized light microscopy and scanning electron microscopy (SEM). The HIP-processed HA coatings displayed an increased density in light microscopy and SEM as compared to plasma-sprayed coatings. Direct bone-implant contact was found in all 3 types of surfaces. However, the production of new bone was far more abundant for the HA-coated implants than for sandblasted cpTi implants. The presence of bone-forming and bone-resorbing cells indicated active bone remodeling in the interface area at 3 months after implant placement. The present results support the view that epitaxial bone growth may occur from the HA-coated implant surface. It was concluded that the increased density of the present HIP-processed HA material does not reduce the bioactive properties of the coatings.

  12. Influence of matrix structure on the abrasion wear resistance and toughness of a hot isostatic pressed white iron matrix composite

    NASA Astrophysics Data System (ADS)

    Pagounis, E.; Lindroos, V. K.; Talvitie, M.

    1996-12-01

    The influence of the matrix structure on the mechanical properties of a hot isostatic pressed (hipped) white iron matrix composite containing 10 vol pct TiC is investigated. The matrix structure was systematically varied by heat treating at different austenitizing temperatures. Various subsequent treatments were also employed. It was found that an austenitizing treatment at higher temperatures increases the hardness, wear resistance, and impact toughness of the composite. Although after every different heat treatment procedure the matrix structure of the composite was predominantly martensitic, with very low contents of retained austenite, some other microstructural features affected the mechanical properties to a great extent. Abrasion resistance and hardness increased with the austenitizing temperature because of the higher carbon content in martensite in the structure of the composite. Optimum impact energy values were obtained with structures containing a low amount of M (M7C3+M23C6) carbides in combination with a decreased carbon content martensite. Structure austenitized at higher temperatures showed the best tempering response. A refrigerating treatment was proven beneficial after austenitizing the composite at the lower temperature. The greatest portion in the increased martensitic transformation in comparison to the unreinforced alloy, which was observed particularly after austenitizing the composite at higher temperatures,[1] was confirmed to be mechanically induced. The tempering cycle might have caused some additional chemically induced transformation. The newly examined iron-based composite was found to have higher wear resistance than the most abrasion-resistant ferroalloy material (white cast iron).

  13. Improving the dielectric and piezoelectric properties of screen-printed Low temperature PZT/polymer composite using cold isostatic pressing

    NASA Astrophysics Data System (ADS)

    Almusallam, A.; Yang, K.; Cao, Z.; Zhu, D.; Tudor, J.; Beeby, S. P.

    2014-11-01

    This paper reports an improvement in dielectric and piezoelectric properties of screen-printed PZT/polymer films for flexible electronics applications using Cold Isostatic Pressing (CIP). The investigation involved half and fully cured PZT/polymer composite pastes with weight ratio of 12:1 to investigate the effect of the CIP process on the piezoelectric and dielectric properties. It was observed that the highest dielectric and piezoelectric properties are achieved at pressures of 5 and 10 MPa for half and fully cured films respectively. The relative dielectric constants were 300 and 245 measured at 1 kHz for the half and fully cured samples. Using unoptimised poling conditions, the initial d33 values were 30 and 35 pC/N for the half and fully cured films, respectively. The fully cured sample was then poled using optimized conditions and demonstrated a d33 of approximately 44 pC/N which is an increase of 7% compared with non-CIP processed materials.

  14. Microstructure, Tensile Properties, and Hot-Working Characteristics of a Hot Isostatic-Pressed Powder Metallurgy Superalloy

    NASA Astrophysics Data System (ADS)

    Chang, Litao; Sun, Wenru; Cui, Yuyou; Yang, Rui

    2017-03-01

    A series of microstructure observation, tensile, and hot compression tests were conducted to investigate the variation of microstructure, tensile properties, and hot-working characteristics of a powder metallurgy (PM) superalloy with hot isostatic pressing (HIPing) temperature, to establish a basis for the parameter selection for PM superalloy preparation. The results show that the dendritic structure from the powder was not completely removed until the HIPing temperature is above the γ' solvus; γ/γ' eutectic formed when the powder particles were HIPed at 1533 K (1260 °C) or above. Prior particle boundaries (PPBs) were observed in alloys HIPed at 1513 K (1240 °C) and below; the PPB decoration is serious in alloys HIPed at 1483 K and 1513 K (1210 °C and 1240 °C), owing to melting and aggregation of the boride phase at the particle boundaries during HIPing; the PPBs were eliminated when the HIPing was done at 1533 K (1260 °C) or above. Tensile fracture mode of the alloy changes from inter-particle and transgranular mixed fracture to transgranular fracture with increasing HIPing temperature, which is in accordance with the change in precipitate distribution at the PPBs. The hot workability of alloy is poor for all combinations of HIPing/deformation conditions except for HIPing at sub-solvus temperature and deformation at low strain rates.

  15. Effect of cold isostatic pressing on the transport current of filamentary MgB2 wire made by the IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Pachla, W.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.

    2016-07-01

    This work describes the effect of cold isostatic pressing applied to as-drawn filamentary wires in a GlidCop and/or Cu sheath made by the internal magnesium diffusion process. Critical currents of as-drawn and isostatically pressed wires at high pressures up to 2.0 GPa followed by heat treatment at 640 °C for 40 min were measured. The obtained results show an improvement in boron powder density resulting in an increase of the critical current of MgB2 layers. The engineering current density increases by 4-13 times after the high-pressure treatment, and is influenced by the density of the boron powder and by the mechanical strength of the outer sheath.

  16. Effect of Tooling Material on the Internal Surface Quality of Ti6Al4V Parts Fabricated by Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Cai, Chao; Song, Bo; Wei, Qingsong; Yan, Wu; Xue, Pengju; Shi, Yusheng

    2017-01-01

    For the net-shape hot isostatic pressing (HIP) process, control of the internal surface roughness of as-HIPped parts remains a challenge for practical engineering. To reveal the evolution mechanism of the internal surface of the parts during the HIP process, the effect of different tooling materials (H13, T8, Cr12 steel, and graphite) as internal cores on the interfacial diffusion and surface roughness was systematically studied.

  17. Tensile properties from room temperature to 1315 C of tungsten-lined tantalum-alloy (T-111) tubing fabricated by hot isostatic pressing

    NASA Technical Reports Server (NTRS)

    Buzzard, R. J.; Metroka, R. R.

    1974-01-01

    The effects were studied of a thin tungsten liner on the tensile properties of T-111 tubing considered for fuel cladding in a space power nuclear reactor concept. The results indicate that the metallurgically bonded liner had no appreciable effects on the properties of the T-111 tubing. A hot isostatic pressing method used to apply the liners is described along with a means for overcoming the possible embrittling effects of hydrogen contamination.

  18. MICROSCOPY CHARACTERIZATION OF U-MO BEARING MINI-PLATES FABRICATED BY HOT ISOSTATIC PRESSING (HIPPING) WITH A LONG THERMAL CYCLE

    SciTech Connect

    Jan-Fong Jue

    2007-07-01

    The RERTR Program has formed the Production Development Team to coordinate fabrication efforts to produce the fuel elements for the qualifying irradiation tests. These fuel elements will be fabricated in production facilities. Fabrication development data will be shared with all participants on the development team. The INL has been developing a method of cladding using a Hot Isostatic Press (HIP). The operating parameters were varied to understand the impact of time, pressure and temperature on the reaction between the fuel and the cladding. This report details some of the data produced to date.

  19. The effect of pre-treatment parameters on the quality of glass-ceramic wasteforms for plutonium immobilisation, consolidated by hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Thornber, Stephanie M.; Heath, Paul G.; Da Costa, Gabriel P.; Stennett, Martin C.; Hyatt, Neil C.

    2017-03-01

    Glass-ceramics with high glass fractions (70 wt%) were fabricated in stainless steel canisters by hot isostatic pressing (HIP), at laboratory scale. High (600 °C) and low (300 °C) temperature pre-treatments were investigated to reduce the canister evacuation time and to understand the effect on the phase assemblage and microstructure of the hot isostatically pressed product. Characterisation of the HIPed materials was performed using scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX) and powder X-ray diffraction (XRD). This analysis showed the microstructure and phase assemblage was independent of the variation in pre-treatment parameters. It was demonstrated that a high temperature pre-treatment of batch reagents, prior to the HIP cycle, is beneficial when using oxide precursors, in order to remove volatiles and achieve high quality dense materials. Sample throughput can be increased significantly by utilising a high temperature ex-situ calcination prior to the HIP cycle. Investigation of glass-ceramic wasteform processing utilising a glass frit precursor, produced a phase assemblage and microstructure comparable to that obtained using oxide precursors. The use of a glass frit precursor should allow optimised throughput of waste packages in a production facility, avoiding the need for a calcination pre-treatment required to remove volatiles from oxide precursors.

  20. Microstructural Evolution and Mechanical Properties of Nanointermetallic Phase Dispersed Al65Cu20Ti15 Amorphous Matrix Composite Synthesized by Mechanical Alloying and Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Roy, D.; Mitra, R.; Ojo, O. A.; Lojkowski, W.; Manna, I.

    2011-08-01

    The structure and mechanical properties of nanocrystalline intermetallic phase dispersed amorphous matrix composite prepared by hot isostatic pressing (HIP) of mechanically alloyed Al65Cu20Ti15 amorphous powder in the temperature range 573 K to 873 K (300 °C to 600 °C) with 1.2 GPa pressure were studied. Phase identification by X-ray diffraction (XRD) and microstructural investigation by transmission electron microscopy confirmed that sintering in this temperature range led to partial crystallization of the amorphous powder. The microstructures of the consolidated composites were found to have nanocrystalline intermetallic precipitates of Al5CuTi2, Al3Ti, AlCu, Al2Cu, and Al4Cu9 dispersed in amorphous matrix. An optimum combination of density (3.73 Mg/m3), hardness (8.96 GPa), compressive strength (1650 MPa), shear strength (850 MPa), and Young's modulus (182 GPa) were obtained in the composite hot isostatically pressed ("hipped") at 773 K (500 °C). Furthermore, these results were compared with those from earlier studies based on conventional sintering (CCS), high pressure sintering (HPS), and pulse plasma sintering (PPS). HIP appears to be the most preferred process for achieving an optimum combination of density and mechanical properties in amorphous-nanocrystalline intermetallic composites at temperatures ≤773 K (500 °C), while HPS is most suited for bulk amorphous alloys. Both density and volume fraction of intermetallic dispersoids were found to influence the mechanical properties of the composites.

  1. Microstructure, Mechanical Properties, and Flatness of SEBM Ti-6Al-4V Sheet in As-Built and Hot Isostatically Pressed Conditions

    NASA Astrophysics Data System (ADS)

    Tang, H. P.; Wang, J.; Song, C. N.; Liu, N.; Jia, L.; Elambasseril, J.; Qian, M.

    2017-03-01

    Sheet (0.41-4.80 mm thick) or thin plate structures commonly exist in additively manufactured Ti-6Al-4V components for load-bearing applications. A batch of 64 Ti-6Al-4V sheet samples with dimensions of 210/180 mm × 42 mm × 3 mm have been additively manufactured by selective electron beam melting (SEBM). A comprehensive assessment was then made of their density, surface flatness, microstructure, and mechanical properties in both as-built and hot isostatically pressed conditions, including the influence of the hot isostatic pressing (HIP) temperature. In particular, standard long tensile (156 mm long, 2 mm thick) and fatigue (206 mm long, 2 mm thick) test sheet samples were used for assessment. As-built SEBM Ti-6Al-4V sheet samples with machined surfaces fully satisfied the minimum tensile property requirements for mill-annealed TIMETAL Ti-6Al-4V sheet products, whereas HIP-processed samples (2 mm thick) with machined surfaces achieved a high cycle fatigue (HCF) strength of 625 MPa (R = 0.06, 107 cycles), similar to mill-annealed Ti-6Al-4V (500-700 MPa). The unflatness was limited to 0.2 mm in both the as-built and HIP-processed conditions. A range of other revealing observations was discussed for the additive manufacturing of the Ti-6Al-4V sheet structures.

  2. The effects of weld-repair and hot isostatic pressing on the fracture properties of Ti-5Al-2.5Sn ELI castings

    NASA Technical Reports Server (NTRS)

    Misra, M. S.; Lemeshewsky, S.; Bolstad, D.

    1982-01-01

    The Ti-5Al-2.5Sn extremely low interstitial alloy employed in the large castings which form the critical attachment fittings of the Space Shuttle External Tank was selected because of its high fracture resistance at cryogenic temperatures. Casting was selected over alternative fabrication methods because of its lower cost and adaptability to design changes, although it was found necessary to weld-repair surface and subsurface casting defects in order to reduce the scrap rate and maintain the inherent cost advantage of the castings. Hot Isostatic Pressing was experimentally found to heal the surface and internal defects of the castings, but did not improve tensile or fracture properties and was therefore rejected as a production technique. Production castings are instead weld-repaired, without any mechanical property degradation.

  3. Significant Improvement of Mechanical Properties in NiAl-Cr(Mo)/Hf Alloy by Suction Casting and Subsequent Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Guo, J. T.; Huai, K. W.; Li, H. T.

    2007-01-01

    The NiAl-28Cr-5.5Mo-0.5Hf eutectic alloy was prepared by the suction casting (SC) technique and subsequent hot isostatic pressing (HIP) treatment, and tested for compressive strength and fracture behavior in the temperature range of 300 to 1373 K. The microstructure of suction-cast alloy is characterized by fine interlamellar spacing, large area fraction of eutectic cell, and fine Heusler (Ni2AlHf) phase distributed semicontinuously at the cell boundaries. After HIP treatment, Ni2AlHf phase at the cell boundaries is transformed into Hf solid solution phase and distributed homogeneously within the NiAl matrix. Compared with the conventionally cast alloy, the room-temperature compressive strain and elevated temperature strength of suction-cast alloy are enhanced markedly after HIP treatment. The reason is that the HIP treatment causes Hf solid solution phase to distribute homogeneously and then strengthens the NiAl matrix.

  4. Understanding the Role of Hot Isostatic Pressing Parameters on the Microstructural Evolution of Ti-6Al-4V and Inconel 718 Fabricated by Electron Beam Melting

    SciTech Connect

    Peter, William H.; Nandwana, Peeyush; Kirka, Michael M.; Dehoff, Ryan R.; Sames, William; Erdman, III, Donald L.; Eklund, Anders; Howard, Ron

    2015-04-01

    In this project, Avure and ORNL evaluated the influence of hot isostatic pressing (HIP) and thermal cycling as standalone post processing techniques on the microstructure of electron beam powder bed deposited Ti-6Al-4V and Inconel 718 alloys. Electron beam powder bed deposition is an effective technology for fabricating complex net shape components that cannot be manufactured with conventional processes. However, material deposited by this technology results in columnar grain growth which is detrimental for many applications. For Ti-6Al-4V, it has been found that thermal cycling alone is not sufficient to breakdown the columnar microstructure that is typical of electron beam powder bed technology. HIP, on the other hand, has the potential to be an effective technique to break down the columnar microstructure of Ti-6Al-4V into a more equiaxed and refined β grain structure, and provide a more homogeneous microstructure compared to the thermally cycled samples. Overall, the project showed that hot isostatic pressing reduced/eliminated porosity in both Ti-6Al-4V and Inconel 718 However, based on the unique thermal cycle and the application of pressure in the HIP vessel, Ti-6Al-4V e-beam deposited microstructures were modified from columnar grain growth to equiaxed microstructures; a significant outcome to this collaboration. Inconel 718, on the other hand, shows no change in the macrostructure as a result of the current HIP cycle based on the thermal history, and would require further investigation. Though the results of HIP cycle were very good at changing the microstructure, further development in optimizing the post heat treatments and HIP cycles is required to improve mechanical properties.

  5. Manufacture and cytotoxicity of a lead-free piezoelectric ceramic as a bone substitute-consolidation of porous lithium sodium potassium niobate by cold isostatic pressing.

    PubMed

    Wang, Qi; Yang, Jun; Zhang, Wu; Khoie, Roxanne; Li, Yi-Ming; Zhu, Jian-Guo; Chen, Zhi-Qing

    2009-06-01

    The piezoelectric properties and cytotoxicity of a porous lead-free piezoelectric ceramic for use as a direct bone substitute were investigated. Cold isostatic pressing (CIP) was applied to fabricate porous lithium sodium potassium niobate (Li0.06Na0.5K0.44) NbO3 specimens using a pore-forming method. The morphologies of the CIP-processed specimens were characterized and compared to those of specimens made by from conventional pressing procedures. The effects of the ceramic on the attachment and proliferation of osteoblasts isolated from the cranium of 1-day-old Sprague-Dawley rats were examined by a scanning electron microscopy (SEM) and methylthiazol tetrazolium (MTT) assay. The results showed that CIP enhanced piezoelectricity and biological performance of the niobate specimen, and also promoted an extracellular matrix-like topography of it. In vitro studies showed that the CIP-enhanced material had positive effects on the attachment and proliferation of osteoblasts. Niobate ceramic generated by CIP shows a promise for being a piezoelectric composite bone substitute.

  6. Manufacture and Cytotoxicity of a Lead-free Piezoelectric Ceramic as a Bone Substitute—Consolidation of Porous Lithium Sodium Potassium Niobate by Cold Isostatic Pressing

    PubMed Central

    Wang, Qi; Yang, Jun; Zhang, Wu; Khoie, Roxanne; Li, Yi-ming; Zhu, Jian-guo; Chen, Zhi-qing

    2009-01-01

    Aim The piezoelectric properties and cytotoxicity of a porous lead-free piezoelectric ceramic for use as a direct bone substitute were investigated. Methodology Cold isostatic pressing (CIP) was applied to fabricate porous lithium sodium potassium niobate (Li0.06Na0.5K0.44) NbO3 specimens using a pore-forming method. The morphologies of the CIP-processed specimens were characterized and compared to those of specimens made by from conventional pressing procedures. The effects of the ceramic on the attachment and proliferation of osteoblasts isolated from the cranium of 1-day-old Sprague-Dawley rats were examined by a scanning electron microscopy (SEM) and methylthiazol tetrazolium (MTT) assay. Results The results showed that CIP enhanced piezoelectricity and biological performance of the niobate specimen, and also promoted an extracellular matrix-like topography of it. In vitro studies showed that the CIP-enhanced material had positive effects on the attachment and proliferation of osteoblasts. Conclusion Niobate ceramic generated by CIP shows a promise for being a piezoelectric composite bone substitute. PMID:20687302

  7. Hot-isostatic pressing of U-10Zr by grain boundary diffusion and creep cavitation. Part 2: Theory and data analysis

    SciTech Connect

    McDeavitt, S.M.; Solomon, A.A.

    1997-08-01

    Uranium-10 wt % zirconium (U-10Zr) is a fuel alloy that has been used in the Experimental Breeder Reactor-II (EBR-II). The high burnup that was desired in this fuel system made high demands on the mechanical compatibility between fuel and cladding both during normal operation and during safety-related transients when rapid differential expansion may cause high stresses. In general, this mechanical stress can be reduced by cladding deformation if the cladding is sufficiently ductile at high burnup, and/or by fuel hot-pressing. Fortunately, the fuel is very porous when it contacts the cladding, but this porosity gradually fills with solid fission products (primarily lanthanides) that may limit the fuel`s compressibility. If the porosity remains open, gaseous fission products are released and the porous fuel creeps rather than hot-presses under contact stresses. If the pores are closed by sintering or by solid fission products, the porous fuel will hot-isostatic press (HIP), as represented by the models to be discussed. HIP experiments performed at 700 C on U-10Zr samples with different impurity phase contents (Part 1) are analyzed in terms of several creep cavitation models. The coupled diffusion/creep cavitation model of Chen and Argon shows good quantitative agreement with measured HIP rates for hydride- and metal-derived U-10Zr materials, assuming that pores are uniformly distributed on grain boundaries and are of modal size, and that far-field strain rates are negligible. The analysis predicts, for the first time, an asymmetry between HIP and swelling at identical pressure-induced driving forces due to differences in grain boundary stresses. The differences in compressibility of hydride- and metal-derived U-10Zr can be partially explained by differences in pore size and spacing. The relevance of the experiments to description of in-reactor densification under external pressure or contact stress due to fuel/cladding mechanical interaction is discussed.

  8. Phase decomposition of γ-U (bcc) in U-10 wt% Mo fuel alloy during hot isostatic pressing of monolithic fuel plate

    NASA Astrophysics Data System (ADS)

    Park, Y.; Eriksson, N.; Newell, R.; Keiser, D. D.; Sohn, Y. H.

    2016-11-01

    Eutectoid decomposition of γ-phase (cI2) into α-phase (oC4) and γ‧-phase (tI6) during the hot isostatic pressing (HIP) of the U-10 wt% Mo (U10Mo) alloy was investigated using monolithic fuel plate samples consisting of U10Mo fuel alloy, Zr diffusion barrier and AA6061 cladding. The decomposition of the γ-phase was observed because the HIP process is carried out near the eutectoid temperature, 555 °C. Initially, a cellular structure, consisting of γ‧-phase surrounded by α-phase, developed from the destabilization of the γ-phase. The cellular structure further developed into an alternating lamellar structure of α- and γ‧-phases. Using scanning electron microscopy and transmission electron microscopy, qualitative and quantitative microstructural analyses were carried out to identify the phase constituents, and elucidate the microstructural development based on time-temperature-transformation diagram of the U10Mo alloy. The destabilization of γ -phase into α- and γ‧-phases would be minimized when HIP process was carried out with rapid ramping/cooling rate and dwell temperature higher than 560 °C.

  9. Effect of Oxygen Content Upon the Microstructural and Mechanical Properties of Type 316L Austenitic Stainless Steel Manufactured by Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Cooper, Adam J.; Cooper, Norman I.; Dhers, Jean; Sherry, Andrew H.

    2016-09-01

    Although hot isostatic pressing (HIP) has been shown to demonstrate significant advances over more conventional manufacture routes, it is important to appreciate and quantify the detrimental effects of oxygen involvement during the HIP manufacture process on the microstructural and material properties of the resulting component. This paper quantifies the effects of oxygen content on the microstructure and Charpy impact properties of HIP'd austenitic stainless steel, through combination of detailed metallographic examination and mechanical testing on HIP'd Type 316L steel containing different concentrations (100 to 190 ppm) of oxygen. Micron-scale pores were visible in the microstructure of the HIP'd materials postmetallographic preparation, which result from the removal of nonmetallic oxide inclusions during metallographic preparation. The area fraction of the resulting pores is shown to correlate with the oxygen concentration which influences the Charpy impact toughness over the temperature range of 77 K to 573 K (-196 °C to 300 °C), and demonstrates the influence of oxygen involved during the HIP manufacture process on Charpy toughness. The same test procedures and microstructural analyses were performed on commercially available forged 316L. This showed comparatively fewer inclusions and exhibited higher Charpy impact toughness over the tested temperature range.

  10. A Microstructural Study on the Observed Differences in Charpy Impact Behavior Between Hot Isostatically Pressed and Forged 304L and 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Cooper, Adam J.; Cooper, Norman I.; Bell, Andrew; Dhers, Jean; Sherry, Andrew H.

    2015-11-01

    With near-net shape technology becoming a more desirable route toward component manufacture due to its ability to reduce machining time and associated costs, it is important to demonstrate that components fabricated via Hot Isostatic Pressing (HIP) are able to perform to similar standards as those set by equivalent forged materials. This paper describes the results of a series of Charpy tests from HIP'd and forged 304L and 316L austenitic stainless steel, and assesses the differences in toughness values observed. The pre-test and post-test microstructures were examined to develop an understanding of the underlying reasons for the differences observed. The as-received microstructure of HIP'd material was found to contain micro-pores, which was not observed in the forged material. In tested specimens, martensite was detectable within close proximity to the fracture surface of Charpy specimens tested at 77 K (-196 °C), and not detected in locations remote from the fracture surface, nor was martensite observed in specimens tested at ambient temperatures. The results suggest that the observed changes in the Charpy toughness are most likely to arise due to differences in as-received microstructures of HIP'd vs forged stainless steel.

  11. Effects of long-time elevated temperature exposures on hot-isostatically-pressed power-metallurgy Udimet 700 alloys with reduced cobalt contents

    NASA Technical Reports Server (NTRS)

    Hart, F. H.

    1984-01-01

    Because almost the entire U.S. consumption of cobalt depends on imports, this metal has been designated "strategic'. The role and effectiveness of cobalt is being evaluated in commercial nickel-base superalloys. Udiment 700 type alloys in which the cobalt content was reduced from the normal 17% down to 12.7%, 8.5%, 4.3%, and 0% were prepared by standard powder metallurgy techniques and hot isostatically pressed into billets. Mechanical testing and microstructural investigations were performed. The mechanical properties of alloys with reduced cobalt contents which were heat-treated identically were equal or better than those of the standard alloy, except that creep rates tended to increase as cobalt was reduced. The effects of long time exposures at 760 C on mechanical properties and at 760 C and 845 C on microstructures were determined. Decreased tensile properties and shorter rupture lives with increased creep rates were observed in alloy modifications. The exposures caused gamma prime particle coarsening and formation of sigma phase in the alloys with higher cobalt contents. Exposure at 845 C also reduced the amount of MC carbides.

  12. Comparative evaluation of electrical conductivity of hydroxyapatite ceramics densified through ramp and hold, spark plasma and post sinter Hot Isostatic Pressing routes.

    PubMed

    Buchi Suresh, M; Biswas, P; Mahender, V; Johnson, Roy

    2017-01-01

    Hydroxyapatite ceramics synthesized through sonochemical route were processed and densified through ramp & hold (R&H) and Spark Plasma Sintering (SPS) routes. The effect of processing route on the relative density and electrical conductivity were studied. Further, the samples were Hot Isostatically Pressed (HIP) under argon pressure at elevated temperature to further densify the sample. All these samples processed under different conditions were characterized by X-ray diffraction, Scanning Electron Microscopy and AC Conductivity. The samples have exhibited hydroxyapatite phase; however, microstructures exhibited distinctly different grain morphologies and grain sizes. AC impedance spectroscopic measurement was carried out on hydroxyapatite samples processed through different routes and the corresponding spectra were analyzed by the analogy to equivalent circuit involving resistors and capacitors. SPS sintered sample after HIPing has exhibited the highest conductivity. This can be attributed to the higher density in combination with finer grain sizes. Activation energy based on Arrhenius equation is calculated and the prominent conduction mechanism is proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Production of an impermeable composite of irradiated graphite and glass by hot isostatic pressing as a long term leach resistant waste form

    SciTech Connect

    Fachinger, Johannes; Muller, Walter; Marsat, Eric; Grosse, Karl-Heinz; Seemann, Richard; Scales, Charlie; Easton, Michael Mark; Anthony Banford

    2013-07-01

    negligible porosity and a water impermeable structure. Structural analysis shows that the glass in the composite has replaced the pores in the graphite structure. The typical pore volume of a graphite material is in the range of 20 vol.%. Therefore no volume increase will occur in comparison with the former graphite material. This IGM material will allow the encapsulation of graphite with package densities larger than 1.5 ton per cubic meter. Therefore a huge volume saving can be achieved by such an alternative encapsulation method. Disposal performance is also enhanced since little or no leaching of radionuclides is observed due to the impermeability of the material NNL and FNAG have proved that IGM can be produced by hot isostatic pressing (HIP) which has several advantages for radioactive materials over the HVP process. - The sealed HIP container avoids the release of any radionuclides. - The outside of the waste package is not contaminated. - The HIP process time is shorter than the HVP process time. The isostatic press avoids anisotropic density distributions. - Simple filling of the HIP container has advantages over the filling of an axial die. (authors)

  14. Growth kinetics and microstructural evolution during hot isostatic pressing of U-10 wt.% Mo monolithic fuel plate in AA6061 cladding with Zr diffusion barrier

    SciTech Connect

    Y. Park; J. Yoo; K. Huang; D. D. Keiser, Jr.; J. F. Jue; B. Rabin; G. Moore; Y. H. Sohn

    2014-04-01

    Phase constituents and microstructure changes in RERTR fuel plate assemblies as functions of temperature and duration of hot-isostatic pressing (HIP) during fabrication were examined. The HIP process was carried out as functions of temperature (520, 540, 560 and 580 °C for 90 min) and time (45–345 min at 560 °C) to bond 6061 Al-alloy to the Zr diffusion barrier that had been co-rolled with U-10 wt.% Mo (U10Mo) fuel monolith prior to the HIP process. Scanning and transmission electron microscopies were employed to examine the phase constituents, microstructure and layer thickness of interaction products from interdiffusion. At the interface between the U10Mo and Zr, following the co-rolling, the UZr2 phase was observed to develop adjacent to Zr, and the a-U phase was found between the UZr2 and U10Mo, while the Mo2Zr was found as precipitates mostly within the a-U phase. The phase constituents and thickness of the interaction layer at the U10Mo-Zr interface remained unchanged regardless of HIP processing variation. Observable growth due to HIP was only observed for the (Al,Si)3Zr phase found at the Zr/AA6061 interface, however, with a large activation energy of 457 ± 28 kJ/mole. Thus, HIP can be carried to improve the adhesion quality of fuel plate without concern for the excessive growth of the interaction layer, particularly at the U10Mo-Zr interface with the a-U, Mo2Zr, and UZr2 phases.

  15. Hot Isostatic Press Can Optimization for Aluminum Cladding of U-10Mo Reactor Fuel Plates: FY12 Final Report and FY13 Update

    SciTech Connect

    Clarke, Kester D.; Crapps, Justin M.; Scott, Jeffrey E.; Aikin, Beverly; Vargas, Victor D.; Dvornak, Matthew J.; Duffield, Andrew N.; Weinberg, Richard Y.; Alexander, David J.; Montalvo, Joel D.; Hudson, Richard W.; Mihaila, Bogdan; Liu, Cheng; Lovato, Manuel L.; Dombrowski, David E.

    2013-08-26

    Currently, the proposed processing path for low enriched uranium – 10 wt. pct. molybdenum alloy (LEU-10Mo) monolithic fuel plates for high power research and test reactors includes hot isostatic pressing (HIP) to bond the aluminum cladding that encapsulates the fuel foil. Initial HIP experiments were performed at Idaho National Laboratory (INL) on approximately ¼ scale “mini” fuel plate samples using a HIP can design intended for these smaller experimental trials. These experiments showed that, with the addition of a co-rolled zirconium diffusion barrier on the LEU-10Mo alloy fuel foil, the HIP bonding process is a viable method for producing monolithic fuel plates. Further experimental trials at Los Alamos National Laboratory (LANL) effectively scaled-up the “mini” can design to produce full-size fuel prototypic plates. This report summarizes current efforts at LANL to produce a HIP can design that is further optimized for higher volume production runs. The production-optimized HIP can design goals were determined by LANL and Babcock & Wilcox (B&W) to include maintaining or improving the quality of the fuel plates produced with the baseline scaled-up mini can design, while minimizing material usage, improving dimensional stability, easing assembly and disassembly, eliminating machining, and significantly reducing welding. The initial small-scale experiments described in this report show that a formed-can approach can achieve the goals described above. Future work includes scaling the formed-can approach to full-size fuel plates, and current progress toward this goal is also summarized here.

  16. Hot isostatically-pressed aluminosilicate glass-ceramic with natural crystalline analogues for immobilizing the calcined high-level nuclear waste at the Idaho Chemical Processing Plant

    SciTech Connect

    Raman, S.

    1993-12-01

    The additives Si, Al, MgO, P{sub 2}O{sub 5} were mechanically blended with fluorinelsodium calcine in varying proportions. The batches were vacuum sealed in stainless steel canisters and hot isostatically pressed at 20,000 PSI and 1000 C for 4 hours. The resulting suite of glass-ceramic waste forms parallels the natural rocks in microstructural and compositional heterogeneity. Several crystalline phases ar analogous in composition and structure to naturally occurring minerals. Additional crystalline phases are zirconia and Ca-Mg borate. The glasses are enriched in silica and alumina. Approximately 7% calcine elements occur dissolved in this glass and the total glass content in the waste forms averages 20 wt%. The remainder of the calcine elements are partitioned into crystalline phases at 75 wt% calcine waste loading. The waste forms were tested for chemical durability in accordance with the MCC1-test procedure. The leach rates are a function of the relative proportions of additives and calcine, which in turn influence the composition and abundances of the glass and crystalline phases. The DOE leach rate criterion of less than 1 g/m{sup 2}-day is met by all the elements B, Cs and Na are increased by lowering the melt viscosity. This is related to increased crystallization or devitrification with increases in MgO addition. This exploratory work has shown that the increases in waste loading occur by preferred partitioning of the calcine components among crystalline and glass phases. The determination of optimum processing parameters in the form of additive concentration levels, homogeneous blending among the components, and pressure-temperature stabilities of phases must be continued to eliminate undesirable effects of chemical composition, microstructure and glass devitrification.

  17. Using a novel technique to shape a refractory castable by Cold Isostatic Pressing and a study of the effect of pressure on the hydration reaction of high-alumina cement

    NASA Astrophysics Data System (ADS)

    Emadi, Rahmatollah; Monshi, Ahmad; Shafyei, Ali

    2007-02-01

    Calcium aluminate cements are the most hydraulically setting cements used for refractory castables. The anhydrous phases of this type of cements incorporate CA, CA2 and traces of C12A7 and alpha-alumina where C and A stand for CaO and Al2O3, respectively. Hydration starts to form the hexagonal crystals of CAH10 (H denoting H2O) and C2AH8, which convert to the cubic crystals of C3AH6 and AH3 by the passage of hydration time. In this work, Al2O3-C (alumina-graphite) castables were shaped by cold isostatic pressing at 100 to 400 bars (≈100 to 400 Kg/cm2). Hydration and conversion reactions were studied using the Ratio of Slopes Method for quantitative XRD studies after 3 and 28 days. The results showed that by increasing the pressure, the kinetics of the hydration reaction will increase and higher strengths can be obtained, which supports the idea of forming this graphite containing castable by Cold Isostatic Pressing (CIP) in industrial applications for special refractories.

  18. Influence of hot isostatic pressing on the structure and properties of an innovative low-alloy high-strength aluminum cast alloy based on the Al-Zn-Mg-Cu-Ni-Fe system

    NASA Astrophysics Data System (ADS)

    Akopyan, T. K.; Padalko, A. G.; Belov, N. A.

    2015-11-01

    Hot isostatic pressing (HIP) is applied for treatment of castings of innovative low-ally high-strength aluminum alloy, nikalin ATs6N0.5Zh based on the Al-Zn-Mg-Cu-Ni-Fe system. The influence of HIP on the structure and properties of castings is studied by means of three regimes of barometric treatment with different temperatures of isometric holding: t 1 = 505 ± 2°C, p 1 = 100 MPa, τ1 = 3 h (HIP1); t 2 = 525 ± 2°C, p 2 = 100 MPa, τ2 = 3 h (HIP2); and t 3 = 545 ± 2°C, p 3 = 100 MPa, τ3 = 3 h (HIP3). It is established that high-temperature HIP leads to actually complete elimination of porosity and additional improvement of the morphology of second phases. Improved structure after HIP provides improvement properties, especially of plasticity. In particular, after heat treatment according of regime HIP2 + T4 (T4 is natural aging), the alloy plasticity is improved by about two times in comparison with the initial state (from ~6 to 12%). While applying regime HIP3 + T6 (T6 is artificial aging for reaching the maximum strength), the plasticity has improved by more than three times in comparison with the initial state, as after treatment according to regimes HIP1 + T6 and HIP2 + T6 (from ~1.2 to ~5.0%), which are characterized by a lower HIP temperature.

  19. Microstructure and Mechanical Properties of Long Ti-6Al-4V Rods Additively Manufactured by Selective Electron Beam Melting Out of a Deep Powder Bed and the Effect of Subsequent Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Lu, S. L.; Tang, H. P.; Ning, Y. P.; Liu, N.; StJohn, D. H.; Qian, M.

    2015-09-01

    An array of eight long Ti-6Al-4V rods (diameter: 12 mm; height: 300 mm) have been additively manufactured, vertically and perpendicular to the powder bed, by selective electron beam melting (SEBM). The purpose was to identify and understand the challenges of fabricating Ti-6Al-4V samples or parts from a deep powder bed (more than 200-mm deep) by SEBM and the necessity of applying post heat treatment. The resulting microstructure and mechanical properties of these Ti-6Al-4V rods were characterized along their building ( i.e., axial) direction by dividing each rod into three segments (top, middle, and bottom), both before ( i.e., as-built) and after hot isostatic pressing (HIP). The as-built microstructure of each rod was inhomogeneous; it was coarsest in the top segment, which showed a near equilibrium α- β lamellar structure, and finest in the bottom segment, which featured a non-equilibrium mixed structure. The tensile properties varied along the rod axis, especially the ductility, but all tensile properties met the requirements specified by ASTM F3001-14. HIP increased the relative density from 99.03 pct of the theoretical density (TD) to 99.90 pct TD and homogenized the microstructure thereby leading to highly consistent tensile properties along the rod axis. The temperature of the stainless steel substrate used in the powder bed was monitored. The as-built inhomogeneous microstructure is attributed to the temperature gradient in the deep powder bed. Post heat treatment is thus necessary for Ti-6Al-4V samples or parts manufactured from a deep powder bed by SEBM. This differs from the additive manufacturing of small samples or parts from a shallow powder bed (less than 100-mm deep) by SEBM.

  20. Bibliography on Hot Isostatic Pressing (HIP) Technology

    DTIC Science & Technology

    1992-11-01

    RENE’ 80, AA C355 . AA A356, 142-T4 16 10. Advanced Processing and Properties of High-Performance Alloys Koss, D. A. Department of Metallurgical...738, RENE’ 77, IN-792, RENE’ 80. AA C355 . AA A356, 142-T4 4. Recent Developments and Trends in High Strength PM Materials Singer, R. F. Powder Metall...B093 IOOL Key Words: Ti-6AI-4V. B-1900. IN-738. RENE* 77, IN-792. RENE’ 80. AA C355 . AA A356, 142-T4 2. Prior Particle Boundary Precipitation in P/M

  1. Hot Isostatic Pressing of Superconducting Ceramics

    DTIC Science & Technology

    1990-10-01

    MONITORING AGENCY NAME & ADDRESS Ifffer’ from Contr/.ng Offe) 115 SECURITY CLASS ., ,r’ni Unclassified ISa. DECLASSIFICATION/DOWNGRADING SCHEDULE 16...Jr., ii. M.. GAL iAGIi IE;R. 1’. K.. Si N:RWOOD. R. C., and JIN. S. warer Interaction with thec superconducting YIia2CuiOi Phbase. Appi. i’hys. Il

  2. An Isostatic Earth Model.

    DTIC Science & Technology

    1985-09-01

    Continue an reer@e side it neceary and Identify by block tmobr) )The concept of the conventional Airy/ Heiskanen isostatic model is investi- gated from...shaped type, and a depth of compensation of about 24 km. A proof of equivalence of using a standard Airy/ Heiskanen model with a larger compensation...postulated. Although in some limited areas the Pratt/Hayford system seemed to prevail, the Airy/ Heiskanen system is now generally believed to model the

  3. Isostaticity in Cosserat Continuum

    DTIC Science & Technology

    2012-01-01

    Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Isostaticity, Cosserat, Granular, Force chains Antoinette ...TELEPHONE NUMBER Antoinette Tordesillas 038-344-9685 3. DATES COVERED (From - To) Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18...Cosserat continuum Antoinette Tordesillas · Jingyu Shi · John F. Peters Received: 29 August 2011 / Published online: 16 March 2012 © Springer-Verlag 2012

  4. On isostatic geoid anomalies

    NASA Technical Reports Server (NTRS)

    Haxby, W. F.; Turcotte, D. L.

    1978-01-01

    In regions of slowly varying lateral density changes, the gravity and geoid anomalies may be expressed as power series expansions in topography. Geoid anomalies in isostatically compensated regions can be directly related to the local dipole moment of the density-depth distribution. This relationship is used to obtain theoretical geoid anomalies for different models of isostatic compensation. The classical Pratt and Airy models give geoid height-elevation relationships differing in functional form but predicting geoid anomalies of comparable magnitude. The thermal cooling model explaining ocean floor subsidence away from mid-ocean ridges predicts a linear age-geoid height relationship of 0.16 m/m.y. Geos 3 altimetry profiles were examined to test these theoretical relationships. A profile over the mid-Atlantic ridge is closely matched by the geoid curve derived from the thermal cooling model. The observed geoid anomaly over the Atlantic margin of North America can be explained by Airy compensation. The relation between geoid anomaly and bathymetry across the Bermuda Swell is consistent with Pratt compensation with a 100-km depth of compensation.

  5. Developing Model-Based Control Strategies for Hot Isostatic Pressing.

    DTIC Science & Technology

    1994-08-31

    feedback. It was found that density feedback based on PI control . (proportional plus integral) has better performance than proporational control alone. The...controller in linear system is the well- known proportional-integration ( PI ) controller . We will see that the unpredictable variations in HIP plant could be...effectively eliminated through PI feedback control. However, it should be noticed that, when introducing a PI control , the proportion gain and the

  6. Development of Hot Isostatically Pressed Rene 95 Turbine Parts

    DTIC Science & Technology

    1977-05-01

    34---.- ~’A4 𔃾 A4 - ’t- Al ’ a % ~ * . Ř lOOX 2000F/15 ksi 50OX Figure~~ ~ 6.. Mirstutue of -60 Mes Vedo B nta.tuyCmat-(he ) -. 4, 38 - .4-I-J En n cn In 0 0... Vedo AAty’ :x&J u-Sud onTs edrAadVno aeil (let) ~4~4 ;147 diameters of each cooling-plate was left intact during heat treatment. All parts were

  7. Results of intermediate-scale hot isostatic press can experiments

    SciTech Connect

    Nelson, L.O.; Vinjamuri, K.

    1995-05-01

    Radioactive high-level waste (HLW) has been managed at the Idaho Chemical Processing Plant (ICPP) for a number of years. Since 1963, liquid HLW has been solidified into a granular solid (calcine). Presently, over 3,800 m{sup 3} of calcine is stored in partially-underground stainless steel bins. Four intermediate- scale HLW can tests (two 6-in OD {times} 12-in tall and two 4-in OD {times} 7-in tall) are described and compared to small-scale HIP can tests (1- to 3-in OD {times} 1- to 4.5-in tall). The intermediate-scale HIP cans were loaded with a 70/30 calcine/frit blend and HIPped at an off-site facility at 1050{degrees}C; and 20 ksi. The dimensions of two cans (4-in OD {times} 7-in tall) were monitored during the HIP cycle with eddy-current sensors. The sensor measurements indicated that can deformation occurs rapidly at 700{degrees}C; after which, there is little additional can shrinkage. HIP cans were subjected to a number of analyses including calculation of the overall packing efficiency (56 to 59%), measurement of glass-ceramic (3.0 to 3.2 g/cc), 14-day MCC-1 leach testing (total mass loss rates < 1 g/m{sup 2} day), and scanning electron microscopy (SEM). Based on these analyses, the glass-ceramic material produced in intermediate-scale cans is similar to material produced in small-scale cans. No major scale-up problems were indicated. Based on the packing efficiency observed in intermediate- and small-scale tests, the overall packing efficiency of production-scale (24-in OD {times} 36- to 190-in tall) cans would be approximately 64% for a pre-HIP right-circular cylinder geometry. An efficiency of 64% would represent a volume reduction factor of 2.5 over a candidate glass waste prepared at 33 wt% waste loading.

  8. An apparatus for studying scintillator properties at high isostatic pressures

    SciTech Connect

    Gaume, R. M.; Lam, S.; Gascon, M.; Feigelson, R. S.; Setyawan, W.; Curtarolo, S.

    2013-01-15

    We describe the design and operation of a unique hydraulic press for the study of scintillator materials under isostatic pressure. This press, capable of developing a pressure of a gigapascal, consists of a large sample chamber pressurized by a two-stage hydraulic amplifier. The optical detection of the scintillation light emitted by the sample is performed, through a large aperture optical port, by a photodetector located outside the pressure vessel. In addition to providing essential pressure-dependent studies on the emission characteristics of radioluminescent materials, this apparatus is being developed to elucidate the mechanisms behind the recently observed dependency of light-yield nonproportionality on electronic band structure. The variation of the light output of a Tl:CsI crystal under 511-keV gamma excitation and hydrostatic pressure is given as an example.

  9. A Geodetic View on Isostatic Models

    NASA Astrophysics Data System (ADS)

    Göttl, Franziska; Rummel, Reiner

    2009-09-01

    Before the background of more accurate and denser gravity data it is worthwhile to reassess geodetic isostasy. Currently, in geodesy isostatic models are primarily applied to gravity reduction as needed by geoid and gravity modeling. The selection of the isostatic model is based on four criteria: Isostatically reduced gravity anomalies should be (1) geophysically meaningful, (2) easy to compute, (3) small, smooth and therefore easy to interpolate and (4) the indirect effect, i.e. the change of potential and gravity due to isostatic mass replacement, should be small. In this study we analyze free air anomalies as well as isostatic anomalies based on the Airy-Heiskanen model and on the Pratt-Hayford model in regard to these criteria. Several facts suggest that free air anomalies are the most realistic type of isostatic anomalies. They reflect the actual isostatic compensation, are easy to compute and their indirect effect is negligibly small. However, they are not smooth due to the fact that local topographic loads are only partially compensated. Smoothness can be achieved by introducing either a mathematical low-pass filter or a hydrostatic isostatic model, such as the Airy-Heiskanen or the Pratt-Hayford model. In both cases the resulting isostatically reduced gravity anomalies fulfill all requirements. In order to improve the numerical efficiency, a new mathematical description of the Pratt-Hayford model is formulated. The level of smoothing with respect to free air anomalies is analyzed in global and regional contexts. It turns out that the mechanism of mass compensation in regions of large topographic loads is better described by the Airy-Heiskanen model, whereas the Pratt-Hayford model is more suitable for regions of deep ocean trenches.

  10. Global map of the isostatic gravity disturbances

    NASA Astrophysics Data System (ADS)

    Tenzer, Robert; Chen, Wenjin; Novák, Pavel

    2013-04-01

    We compile and compare global maps of the isostatic gravity disturbances for different isostatic models. The Airy-Heiskanen, Prat-Hayford and Vening-Meinesz Moritz models of isostasy are taken into consideration. These isostatic gravity data are then used to interpret the Earth's inner density structures and geophysical processes occurring within the lithosphere and sub-lithosphere mantle. The investigation is done separately for the oceanic and continental crustal structures. The isostatic gravity disturbances are computed globally using the global geopotential model (GOCO-03c), global topographic/bathymetric model (DTM2006.0) including ice-thickness data, and sediment data taken form the global crustal model (CRUST2.0).

  11. Isostatic geoid anomalies on a sphere

    NASA Technical Reports Server (NTRS)

    Dahlen, F. A.

    1982-01-01

    Long-wavelength geoid anomalies due to lateral variations in the density or thickness of a thin layer in local isostatic equilibrium on the surface of a sphere depend sensitively on the assumed state of stress within the layer. A number of common intuitive definitions of local isostasy generally believed to be essentially identical are associated with quite different states of isostatic stress, and the corresponding theoretical geoid anomalies can vary by more than a factor of 2. This sensitivity of the theoretical anomaly to the exact definition of local isostasy constitutes an obstacle to any proposed program of interpreting or exploiting observed global isostatic geoid anomalies such as those associated with the aging of the oceanic lithosphere.

  12. Elastic collapse in disordered isostatic networks

    NASA Astrophysics Data System (ADS)

    Moukarzel, C. F.

    2012-02-01

    Isostatic networks are minimally rigid and therefore have, generically, nonzero elastic moduli. Regular isostatic networks have finite moduli in the limit of large sizes. However, numerical simulations show that all elastic moduli of geometrically disordered isostatic networks go to zero with system size. This holds true for positional as well as for topological disorder. In most cases, elastic moduli decrease as inverse power laws of system size. On directed isostatic networks, however, of which the square and cubic lattices are particular cases, the decrease of the moduli is exponential with size. For these, the observed elastic weakening can be quantitatively described in terms of the multiplicative growth of stresses with system size, giving rise to bulk and shear moduli of order e-bL. The case of sphere packings, which only accept compressive contact forces, is considered separately. It is argued that these have a finite bulk modulus because of specific correlations in contact disorder, introduced by the constraint of compressivity. We discuss why their shear modulus, nevertheless, is again zero for large sizes. A quantitative model is proposed that describes the numerically measured shear modulus, both as a function of the loading angle and system size. In all cases, if a density p>0 of overconstraints is present, as when a packing is deformed by compression or when a glass is outside its isostatic composition window, all asymptotic moduli become finite. For square networks with periodic boundary conditions, these are of order \\sqrt{p} . For directed networks, elastic moduli are of order e-c/p, indicating the existence of an "isostatic length scale" of order 1/p.

  13. Isostatic Model and Isostatic Gravity Anomalies of the Arabian Plate and Surroundings

    NASA Astrophysics Data System (ADS)

    Kaban, Mikhail K.; El Khrepy, Sami; Al-Arifi, Nassir

    2016-04-01

    The isostatic modeling represents one of the most useful "geological" reduction methods of the gravity field. With the isostatic correction, it is possible to remove a significant part of the effect of deep density heterogeneity, which dominates in the Bouguer gravity anomalies. Although there exist several isostatic compensation schemes, it is usually supposed that a choice of the model is not an important factor to first order, since the total weight of compensating masses remains the same. We compare two alternative models for the Arabian plate and surrounding area. The Airy model gives very significant regional isostatic anomalies, which cannot be explained by the upper crust structure or disturbances of the isostatic equilibrium. Also, the predicted "isostatic" Moho is very different from existing seismic observations. The second isostatic model includes the Moho, which is based on seismic determinations. Additional compensation is provided by density variations within the lithosphere (chiefly in the upper mantle). According to this model, the upper mantle under the Arabian Shield is less dense than under the Platform. In the Arabian platform, the maximum density coincides with the Rub' al Khali, one of the richest oil basin in the world. This finding agrees with previous studies, showing that such basins are often underlain by dense mantle, possibly related to an eclogite layer that has caused their subsidence. The mantle density variations might be also a result of variations of the lithosphere thickness. With the combined isostatic model, it is possible to minimize regional anomalies over the Arabian plate. The residual local anomalies correspond well to tectonic structure of the plate. Still very significant anomalies, showing isostatic disturbances of the lithosphere, are associated with the Zagros fold belt, the collision zone of the Arabian and Eurasian plates.

  14. Drill Presses.

    ERIC Educational Resources Information Center

    Engelbrecht, Nancy; And Others

    These instructional materials provide an orientation to the drill press for use at the postsecondary level. The first of seven sections lists seven types of drill presses. The second section identifies 14 drill press parts. The third section lists 21 rules for safe use of drilling machines. The fourth section identifies the six procedures for…

  15. ICSU press

    NASA Astrophysics Data System (ADS)

    The International Council of Scientific Unions (ICSU) has established a publishing arm called ICSU Press. The Press is intended to complement the publishing activities of its member scientific unions in several ways: initiate special publications of research findings and new journals of reviews or research; advise, or act as publishers for, members requesting such service; and engage in copublishing ventures with international bodies outside of ICSU whose goals are consistent with ICSU's.Plans for ICSU Press also include preparation of television programs in cooperation with BBC-2 in Britain and PBS and ABC in the United States.

  16. Toward a Next Generation of Isostatic Analysis

    NASA Astrophysics Data System (ADS)

    Lowry, A. R.

    2007-12-01

    Much of the effort to improve upon coherence analysis of isostatic response since Forsyth's&p [1985] introduction has focused on optimizing resolution/bias using more advanced power spectral estimators or wavelets. Less attention has been paid to Forsyth's innovative recognitions that (1) internal loads significantly impact Te estimates, (2) any arbitrary choice of Te exactly models observed gravity and topography given the right combination of surface and internal loading, and (3) an incorrect choice of Te or other parameter to deconvolve surface from internal loads artificially correlates load estimates, making the parameterization that minimizes correlation the likely optimal choice. However, a drawback of parameterizing isostasy by minimizing load correlation is that accuracy of the result hinges on the assumption that surface and internal load processes truly are uncorrelated. Simulations demonstrate that error in recovery of Te arises because, even when synthetic load fields are truly uncorrelated, sub-sampling the data in windows, tapers or wavelets incurs random, spurious correlation at certain locations and wavelengths. As the inexorable march of EarthScope's transportable array of seismic stations proceeds across the country, we are approaching a time when assumptions about load statistics may be downweighted or even unnecessary in isostatic analyses (in the conterminous US at least). Seismic velocities (e.g. from Pn, body and surface wave tomography) and layer thicknesses (from P-S conversions) may be used via regression and/or correlation analyses with gravity/topography data to arrive at independent estimates of internal loading that can then be used to better constrain Te. Seismic data will also aid in overcoming another significant limitation of Forsyth's deconvolution approach. Load deconvolution assumes the internal load mass occurs at a single depth (dictated by the fact that we can solve for at most two unknown amplitudes from the two

  17. High-temperature ultrasonic sensor for in-situ monitoring of hot isostatic processing

    NASA Astrophysics Data System (ADS)

    Stubbs, David A.; Dutton, Rollie E.

    1996-11-01

    A sensor has been developed and tested that is capable of emitting and receiving ultrasonic energy at temperatures exceeding 900 degrees C and pressures above 150 MPa. The sensor is based on a unique form of aluminum nitride that retains tits piezoelectric properties at high temperatures. The sensor works with standard ultrasonic pulse-receivers and has demonstrated the capability of measuring workpiece deformation during hot isostatic pressing (HIP). Details of the sensor design, performance, and coupling of the ultrasound to the workpiece are described. Ultrasonic data acquired by the sensor, in situ, during HIP runs and at elevated temperatures in air are presented.

  18. Development of Casting Process for Pressings of Pistons of Car Augmented Engines

    NASA Astrophysics Data System (ADS)

    Korostelev, V. F.; Denisov, M. S.

    2017-01-01

    Results of a study aimed at formation of a single-phase fine-grained structure in pistons during their production process involving isostatic pressing of liquid metal prior to the start of crystallization, pressing of the crystallizing metal, and holding under pressure in the process of cooling to the shop temperature are presented.

  19. Measurements of Glacial Isostatic Adjustment in Greenland

    NASA Astrophysics Data System (ADS)

    Khan, Shfaqat Abbas; Bamber, Jonathan; Bevis, Michael; Wahr, John; van dam, Tonie; Wouters, Bert; Willis, Michael

    2015-04-01

    The Greenland GPS network (GNET) was constructed to provide a new means to assess viscoelastic and elastic adjustments driven by past and present-day changes in ice mass. Here we assess existing glacial isostatic adjustments (GIA) models by analysing 1995-present data from 61 continuous GPS receivers located along the edge of the Greenland ice sheet. Since GPS receivers measure both the GIA and elastic signal, we isolate the GIA signal, by removing the elastic adjustments of the crust due to present-day mass loss using high-resolution ice surface elevation change grids derived from satellite and airborne altimetry measurements (ERS1/2, ICESat, ATM, ENVISAT, and CryoSat-2). In general, our observed GIA rates contradict models, suggesting GIA models and hence their ice load history for Greenland are not well constrained.

  20. Erosion, isostatic response, and the missing peneplains

    NASA Astrophysics Data System (ADS)

    Phillips, Jonathan D.

    2002-06-01

    The peneplain—a low-relief erosional plain worn to near base level—is a venerable concept in geomorphology, geology, and geography. Yet despite more than a century of effort, no convincing example of a contemporary peneplain has been identified, and the identification of relict peneplains is uncertain and controversial. As a peneplain is a logical outcome during a period of long tectonic stability, the paucity or absence of peneplains is problematic. Most explanations are based on the notion that the periods of tectonic stability required for peneplain formation are too long to allow the features to fully develop, or that Neogene tectonics has precluded recent peneplanation. This paper proposes an alternative explanation, generally consistent with those given above, which can also explain the absence of peneplains in regions experiencing long tectonic stability. If erosion or deposition rates are related to elevation and if isostatic response (uplift or subsidence) is related to erosional unloading or depositional loading, the relationship between these components is dynamically unstable. This is demonstrated mathematically. This instability implies that no particular state or mode of topographic evolution, including peneplanation, is likely to persist in the face of variations or perturbations that influence any system component. Thus, formation of a peneplain would require tectonic stability and also relative constancy in sea level (or rates and direction of sea level change), climate, biotic influences on erosion or deposition, and any other factors that modify erosion, deposition, elevation fields, or isostatic responses. This would explain an absence of geologically contemporary peneplains and a rarity of well-developed peneplains in the geologic record.

  1. Glacial isostatic uplift of the European Alps

    NASA Astrophysics Data System (ADS)

    Mey, Juergen; Scherler, Dirk; Wickert, Andrew D.; Egholm, David L.; Tesauro, Magdala; Schildgen, Taylor F.; Strecker, Manfred R.

    2016-04-01

    Present-day vertical movements of the Earth's surface are mostly due to tectonic deformation, volcanic processes, and crustal loading/unloading. In tectonically stable regions of North America and Scandinavia, vertical movements are almost entirely attributable to glacial isostatic rebound after the melting of the Laurentide and Fennoscandian ice sheets. In contrast, the Pleistocene Alpine icecap grew on a younger mountain belt that formed by collision of the European and African plates, still subject to shortening. Therefore, measured uplift is potentially a composite signal of tectonic shortening and unloading after deglaciation and concomitant erosion. Deciphering the contributions of tectonics and crustal unloading to present-day uplift rates in formerly-glaciated mountain belts is a prerequisite to using uplift data to estimate the viscosity structure of the Earth's mantle, a key variable in geodynamics. We evaluate the post-LGM glacial-isostatic rebound of the Alps following a 4-tiered procedure. First, we estimated the thickness distribution of sedimentary valley fills to create a bedrock map of the entire mountain belt. Second, this map was used as topographic basis for the reconstruction of the Alpine icecap using a numerical ice-flow model. Third, we estimated the equilibrium deflection of the Alpine lithosphere, using the combined loads of ice and sediments with a variable effective elastic thickness. Finally, we used an exponential decay function to infer the residual deflection and the present-day uplift rate for a range of upper mantle viscosities. Our analysis shows that virtually all of the geodetically measured surface uplift in the Swiss and the Austrian Alps can be attributed to glacial unloading and redistribution of sediments, assuming an upper-mantle viscosity lower than that inferred for an old craton (e.g., Fennoscandia), but higher than that for a region with recent crustal thinning (e.g., Basin and Range province).

  2. Adapting isostatic microbial growth parameters into non-isostatic models for use in dynamic ecosystems

    NASA Astrophysics Data System (ADS)

    Spangler, J.; Schulz, C. J.; Childers, G. W.

    2009-12-01

    Modeling microbial respiration and growth is an important tool for understanding many geochemical systems. The estimation of growth parameters relies on fitting experimental data to a selected model, such as the Monod equation or some variation, most often under batch or continuous culture conditions. While continuous culture conditions can be analogous to some natural environments, it often isn’t the case. More often, microorganisms are subject to fluctuating temperature, substrate concentrations, pH, water activity, and inhibitory compounds, to name a few. Microbial growth estimation under non-isothermal conditions has been possible through use of numerical solutions and has seen use in the field of food microbiology. In this study, numerical solutions were used to extend growth models under more non-isostatic conditions using momentary growth rate estimates. Using a model organism common in wastewater (Paracoccus denitrificans), growth and respiration rate parameters were estimated under varying static conditions (temperature, pH, electron donor/acceptor concentrations) and used to construct a non-isostatic growth model. After construction of the model, additional experiments were conducted to validate the model. These non-isostatic models hold the potential for allowing the prediction of cell biomass and respiration rates under a diverse array of conditions. By not restricting models to constant environmental conditions, the general applicability of the model can be greatly improved.

  3. Isostatic GOCE Moho model for Iran

    NASA Astrophysics Data System (ADS)

    Eshagh, Mehdi; Ebadi, Sahar; Tenzer, Robert

    2017-05-01

    One of the major issues associated with a regional Moho recovery from the gravity or gravity-gradient data is the optimal choice of the mean compensation depth (i.e., the mean Moho depth) for a certain area of study, typically for orogens characterised by large Moho depth variations. In case of selecting a small value of the mean compensation depth, the pattern of deep Moho structure might not be reproduced realistically. Moreover, the definition of the mean compensation depth in existing isostatic models affects only low-degrees of the Moho spectrum. To overcome this problem, in this study we reformulate the Sjöberg and Jeffrey's methods of solving the Vening-Meinesz isostatic problem so that the mean compensation depth contributes to the whole Moho spectrum. Both solutions are then defined for the vertical gravity gradient, allowing estimating the Moho depth from the GOCE satellite gravity-gradiometry data. Moreover, gravimetric solutions provide realistic results only when a priori information on the crust and upper mantle structure is known (usually from seismic surveys) with a relatively good accuracy. To investigate this aspect, we formulate our gravimetric solutions for a variable Moho density contrast to account for variable density of the uppermost mantle below the Moho interface, while taking into consideration also density variations within the sediments and consolidated crust down to the Moho interface. The developed theoretical models are applied to estimate the Moho depth from GOCE data at the regional study area of the Iranian tectonic block, including also parts of surrounding tectonic features. Our results indicate that the regional Moho depth differences between Sjöberg and Jeffrey's solutions, reaching up to about 3 km, are caused by a smoothing effect of Sjöberg's method. The validation of our results further shows a relatively good agreement with regional seismic studies over most of the continental crust, but large discrepancies are

  4. Isostatic compensation of the Scandinavian mountains

    NASA Astrophysics Data System (ADS)

    Olesen, O.; Skilbrei, J. R.

    2003-04-01

    As yet, there is no generally accepted hypothesis that explains the Neogene uplift phase of the Scandinavian mountains. Gravity data provide means to study the mechanism of exhumation of these mountainous areas. Assuming that the region is close to isostatic equilibrium, these uplifted mountainous areas must be supported at depth by substantial volumes of low-density material within the crust or the mantle, or at the crust/mantle or lithosphere/asthenosphere interfaces. The former models represent a Pratt type isostacy model, while the two latter are consistent with an Airy-Heiskanen type model. The observed Bouguer gravity field has been compared with gravity responses from Airy roots at various depths below the Scandinavia mountains. The calculated gravity is most similar to the observed gravity field for low-density rocks at a shallow depth in northern Norway. The calculated RMS (root mean square) is lowest (25.0 mGal) for the 10 km Airy root model. This differs significantly from the southern mountains where the RMS is lowest (17.6 mGal) for the 45 km Airy root model. The latter must be partly supported by low-density rocks below the Moho. The Neogene uplift of southern Norway may therefore originate from low-density mantle rocks possibly linked to the Iceland hotspot. The Pratt type of isostasy is consequently deduced to be important for the isostatic compensation of the Scandinavian mountains. The results are in agreement with the conclusions of Riis (1996) and Lidmar-Bergström (1999) that the southern Norwegian plateau was partly uplifted in the Neogene, while the northern Scandinavian mountains originated mainly as a rift-shoulder in late Cretaceous to early Tertiary times. Hendriks &Andriessen (2002) reported that analyses of observed apatite fission track data along a profile from Lofoten into Sweden fits best with those expected from a retreating scarp model. References Hendriks, B.W.H. &Andriessen, P.A.M. 2002: Vertical movements on the Norwegian

  5. New isostatic model of the lithosphere and gravity field

    NASA Astrophysics Data System (ADS)

    Kaban, M. K.; Schwintzer, P.; Reigber, Ch.

    2003-04-01

    A new global model of the isostatic gravity field based on the up-to-date data sets is computed in terms of gravity and geoid. The initial gravity field model is improved using the new CHAMP data. For a construction of the isostatic model of the lithosphere we use the latest compilation of crustal data. Globally this is the CRUST2.0 model, which is supplemented by detailed original data for large parts of North America and North Eurasia. The long-wavelengths of the computed isostatic anomalies up to spherical harmonic degree 20 reflect deep density heterogeneities and the influence of mantle convection through the dynamic topography. The signal contribution of the isostatically balanced lithosphere to the observed gravity or geoid is still significant also for the long-wavelengths: -30- +60 mGal and -15- +40 m peak-to-peak, respectively. Generally the long-wavelength isostaticaly reduced gravity field has much less correlation with the lithosphere patterns than the observed field. This demonstrates that the long-wavelength isostatic gravity field is more appropriate for a modelling of mantle convection than the observed one. The smaller scale isostatic anomalies (wavelengths less than 2000 km) on the other hand are highly sensitive to the quality of the input data used for their computation. To a large extent they reflect internal crustal density inhomogeneities, not included in the isostatic compensation scheme, and uncertainties in the initial crustal data. Thus, small-scale isostatic anomalies may not be always interpreted as a measure of the disturbances of isostatic balance of the lithosphere. Instead we suggest to compute for the smaller scale spectral part the non-isostatic residual topography. The initial crust - upper mantle density model is corrected by gravity inversion in a least squares adjustment. Then, the residual (unbalanced) topography computed with the corrected density distribution represents the isostatic state of the lithosphere. The maximum

  6. Percolating Contact Subnetworks on the Edge of Isostaticity

    DTIC Science & Technology

    2011-01-01

    chains, Force cycles, Isostatic Antoinette Tordesillas, Colin Thornton, Robert P. Behringer, Jie Zhang, John F. Peters, David M. Walker University of...ARO 8. PERFORMING ORGANIZATION REPORT NUMBER 19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER Antoinette Tordesillas 038-344-9685 3. DATES...233–240 DOI 10.1007/s10035-011-0250-y ORIGINAL PAPER Percolating contact subnetworks on the edge of isostaticity David M. Walker · Antoinette

  7. The isostatic state of Mead crater

    NASA Technical Reports Server (NTRS)

    Banerdt, W. B.; Konopliv, A. S.; Rappaport, N. J.; Sjogren, W. L.; Grimm, R. E.; Ford, P. G.

    1994-01-01

    We have analyzed high-resolution Magellan Doppler tracking data over Mead crater, using both line-of-sight and spherical harmonic methods, and have found a negative gravity anomaly of about 4-5 mgal (at spacecraft altitude, 182 km). This is consistent with no isostatic compensation of the present topography; the uncertainty in the analysis allows perhaps as much as 30% compensation at shallow dpeths (approximately 25 km). This is similar to observations of large craters on Earth, which are not generally compensated, but contrasts with at least some lunar basins which are inferred to have large Moho uplifts and corresponding positive Bouguer anomalies. An uncompensated load of this size requires a lithosphere with an effective elastic lithosphere thickness greater than 30 km. In order for the crust-mantle boundary not to have participated in the deformation associated with the collapse of the transient cavity during the creation of the crater, the yield strength near the top of the mantle must have been significantly higher on Earth and Venus than on the Moon at the time of basin formation. This might be due to increased strength against frictional sliding at the higher confining pressures within the larger planets. Alternatively, the thinner crusts of Earth and Venus compared to that of the Moon may result in higher creep strength of the upper mantle at shallower depths.

  8. Numerical simulation of Glacial Isostatic Adjustment

    NASA Astrophysics Data System (ADS)

    Miglio, E.

    2015-12-01

    In the Earth's crust, stress can be subdivided into tectonic background stress, overburden pressure, and pore-fluid pressure. The superposition of the first two and the variation of the third part are key factors in controlling movement along faults. Furthermore, stresses due to sedimentation and erosion contribute to the total stress field. In deglaciated regions, an additional stress must be considered: the rebound stress, which is related to rebounding of the crust and mantle after deglaciation. During the growth of a continental ice sheet, the lithosphere under the iceload is deformed and the removal of the ice load during deglaciation initiates a rebound process. The uplift is well known in formerly glaciated areas, e.g.North America and Scandinavia, and in currently deglaciating areas, e.g.Alaska, Antarctica, and Greenland. The whole process of subsiding and uplifting during the growth and melting of an iceload and all related phenomena is known as glacial isostatic adjustment. During the process of glaciation, the surface of the lithosphere is depressed underneath the ice load and compressional flexural stresses are induced in the upper lithosphere, whereas the bottom of the lithosphere experiences extensional flexural stresses; an additional vertical stress due to the ice load is present and it decreases to zero during deglaciation. During rebound, flexural stresses relax slowly. These stresses are able to change the original stress directions and regime.In this work we aim to study the effect of the GIA process in the context of petroleum engineering. The main aspect we will focus on is the mathematical and numerical modeling of the GIA including thermal effects. We plan also to include a preliminary study of the effect of the glacial erosion. All these phenomena are of paramount importance in petroleum engineering: for example some reservoir have been depleted due to tilting caused by both GIA, erosion and thermal effects.

  9. Isostatic compensation of equatorial highlands on Venus

    NASA Technical Reports Server (NTRS)

    Kucinskas, Algis B.; Turcotte, Donald L.

    1994-01-01

    Spherical harmonic models for Venus' global topography and gravity incorporating Magellan data are used to test isostatic compensation models in five 30 deg x 30 deg regions representative of the main classes of equatorial highlands. The power spectral density for the harmonic models obeys a power-law scaling with spectral slope Beta approximately 2 (Brown noise) for the topography and Beta approximately 3 (Kaula's law) for the geoid, similar to what is observed for Earth. The Venus topography spectrum has lower amplitudes than Earth's which reflects the dominant lowland topography on Venus. Observed degree geoid to topography ratios (GTRs) on Venus are significantly smaller than degree GTRs for uncompensated topography, indicative of substantial compensation. Assuming a global Airy compensation, most of the topography is compensated at depths greater than 100 km, suggesting a thick lithosphere on Venus. For each region considered we obtain a regional degree of compensation C from a linear regression of Bouguer anomaly versus Bouguer gravity data. Geoid anomaly (N) versus topography variation (h) data for each sample were compared, in the least-squares sense, to theoretical correlations for Pratt, Airy, and thermal thinning isostasy models yielding regional GTR, zero-elevation crustal thickness (H), and zero elevation thermal lithosphere thickness (y(sub L(sub 0)), respectively. We find the regional compensation to be substantial (C approximately 52-80%), and the h, N data correlations in the chosen areas can be explained by isostasy models applicable on the Earth and involving variations in crustal thickness (Airy) and/or lithospheric (thermal thinning) thickness. However, a thick crust and lithosphere (y(sub L(sub 0)) approximately 300 km) must be assumed for Venus.

  10. Press Start

    NASA Astrophysics Data System (ADS)

    Harteveld, Casper

    This level sets the stage for the design philosophy called “Triadic Game Design” (TGD). This design philosophy can be summarized with the following sentence: it takes two to tango, but it takes three to design a meaningful game or a game with a purpose. Before the philosophy is further explained, this level will first delve into what is meant by a meaningful game or a game with a purpose. Many terms and definitions have seen the light and in this book I will specifically orient at digital games that aim to have an effect beyond the context of the game itself. Subsequently, a historical overview is given of the usage of games with a serious purpose which starts from the moment we human beings started to walk on our feet till our contemporary society. It turns out that we have been using games for all kinds of non-entertainment purposes for already quite a long time. With this introductory material in the back of our minds, I will explain the concept of TGD by means of a puzzle. After that, the protagonist of this book, the game Levee Patroller, is introduced. Based on the development of this game, the idea of TGD, which stresses to balance three different worlds, the worlds of Reality, Meaning, and Play, came into being. Interested? Then I suggest to quickly “press start!”

  11. Structural Behavior of Monolithic Fuel Plates During Hot Isostatic Pressing and Annealing

    SciTech Connect

    Pavel G. Medvedev; Hakan Ozaltun

    2010-03-01

    This paper presents results of the stress analysis in the monolithic fuel plates during thermal transients performed using COMSOL finite element analysis software. Large difference in the thermal expansion between the U-Mo foil and Al cladding is the main load origin during heating and cooling of the fuel plates. In addition, the mechanical behavior of the plate is affected by the difference in yield points between the foil and the cladding. This is manifested by the plastic deformation and permanent strains in the cladding, and elastic deformation of the foil. The results show existence of the critical temperature points at which the stresses change from compressive to tensile. The paper highlights principal differences in mechanical behavior between monolithic and dispersion fuel plates, underlines the need for mechanical property data, especially for the U-Mo alloys, and discusses the methodology for mechanical analysis of the monolithic plates.

  12. Flexural strength and the probability of failure of cold isostatic pressed zirconia core ceramics.

    PubMed

    Siarampi, Eleni; Kontonasaki, Eleana; Papadopoulou, Lambrini; Kantiranis, Nikolaos; Zorba, Triantafillia; Paraskevopoulos, Konstantinos M; Koidis, Petros

    2012-08-01

    The flexural strength of zirconia core ceramics must predictably withstand the high stresses developed during oral function. The in-depth interpretation of strength parameters and the probability of failure during clinical performance could assist the clinician in selecting the optimum materials while planning treatment. The purpose of this study was to evaluate the flexural strength based on survival probability and Weibull statistical analysis of 2 zirconia cores for ceramic restorations. Twenty bar-shaped specimens were milled from 2 core ceramics, IPS e.max ZirCAD and Wieland ZENO Zr, and were loaded until fracture according to ISO 6872 (3-point bending test). An independent samples t test was used to assess significant differences of fracture strength (α=.05). Weibull statistical analysis of the flexural strength data provided 2 parameter estimates: Weibull modulus (m) and characteristic strength (σ(0)). The fractured surfaces of the specimens were evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The investigation of the crystallographic state of the materials was performed with x-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. Higher mean flexural strength (P<.001) and σ(0) were recorded for WZ ceramics. However IZ ceramics presented a higher m value and a microstructure with fewer voids and pores. The fractured surfaces presented similar fractographic properties (mirror regions followed by hackle lines zones). Both groups primarily sustained the tetragonal phase of zirconia and a negligible amount of the monoclinic phase. Although both zirconia ceramics presented similar fractographic and crystallographic properties, the higher flexural strength of WZ ceramics was associated with a lower m and more voids in their microstructure. These findings suggest a greater scattering of strength values and a flaw distribution that are expected to increase failure probability. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  13. A Comparison of Various Non-Destructive Inspection Processes Using Hot Isostatically Pressed Powder Turbine Parts

    DTIC Science & Technology

    1976-12-01

    and photon scattering (Compton) methods offer much promise. Both I are readily adaptable to fully automatic inspection of hardware. Both appear cost ...effective based on projected production inspection costs . Both make it possible to reduce metal envelopes of raw material thus decreasing material... costs . The acoustical holography process represents a later stage of development than the photon scattering method but both processes require additional

  14. Properties of tritium/helium release from hot isostatic pressed beryllium of various trademarks

    NASA Astrophysics Data System (ADS)

    Chekushina, Lyudmila; Dyussambaev, Daulet; Shaimerdenov, Asset; Tsuchiya, Kunihiko; Takeuchi, Tomoaki; Kawamura, Hiroshi; Kulsartov, Timur

    2014-09-01

    Samples of three industrial beryllium trademarks, such as S-200F, S-65H and I-220H are irradiated at about 40 °C to the fluence of 1.5 × 1024 m-2 (E > 1.15 MeV) in reactor WWR-K. On completion of irradiation tests, post irradiation examinations (PIEs) against hardness are carried out, X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) observation. Also He/T2 release properties are measured by the thermal desorption (TDS) method. Relevant obtained values of amounts of the released tritium and helium for all samples of irradiated beryllium are in good agreement, within inaccuracy, comprising 25 ± 3 wppm for helium-4 and 1.3 ± 0.3 wppm for tritium.

  15. Mechanical Property Development in Hot Isostatic Pressed (HIP) Low Alloy Steel Powder.

    DTIC Science & Technology

    1986-01-01

    Princeton, NJ- 9. R. S. DeFries , C. J. Nolan, and T. V. Brassard, "Observa- tions on the Relationship between Microstructure and Mechanical Properties in...Brassard, and R. S. DeFries , "How Microstructure Influences Mechanical Properties of Forgings," Met. Engr. Quart., May, 1973. 7 , TABLE I Physical

  16. Synthesis of increased-density bismuth-based superconductors with cold isostatic pressing and heat treating

    DOEpatents

    Lanagan, Michael T.; Picciolo, John J.; Dorris, Stephen E.

    1997-01-01

    The present invention is directed to a process for producing high temperature superconducting ceramic materials. More particularly, the present invention is directed to a process that enhances the densification of Bi.sub.1.8 Pb.sub.0.4 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10 "BSCCO" ceramics.

  17. Development of a high strength hot isostatically pressed /HIP/ disk alloy, MERL 76

    NASA Technical Reports Server (NTRS)

    Evans, D. J.; Eng, R. D.

    1980-01-01

    A nickel-based powder metal disk alloy developed for use in advanced commercial gas turbines is described. Consideration is given to final alloy chemistry modifications made to achieve a desirable balance between tensile strength and stress rupture life and ductility. The effects of post-consolidation heat treatment are discussed, the preliminary mechanical properties obtained from full-scale turbine disks are presented.

  18. Improvement of creep resistance of sintered silicon nitride by hot isostatic exudation of intergranular glass

    SciTech Connect

    Rouxel, T.; Besson, J. ); Goursat, P. )

    1993-11-01

    Postsintering treatment of pressureless-sintered silicon nitride at 1,250 C (i.e., above the glass transition temperature of the amorphous phase) by hot isostatic pressing was performed to diminish the quantity of residual intergranular amorphous phase that results from densification aids. The samples were first embedded in a powder (SiC or Al[sub 2]O[sub 3]), which worked as a diffusion barrier and a pressure transmitter; then, both sample and surrounding powder were encapsulated in evacuated tubes of borosilicate glass or stainless steel. Energy dispersive X-ray spectrometry proved that, during the treatment, a noticeable amount of intergranular vitreous phase exuded out of the sample into powder pores. As a consequence, the creep resistance was enhanced by a factor of 3. When the HIP treatment was associated with a subsequent crystallization treatment, a further improvement in creep resistance was obtained.

  19. Glacial Isostatic Adjustment Observed with VLBI and SLR

    NASA Technical Reports Server (NTRS)

    Argus, D.; Peltier, W.; Watkins, M.

    1999-01-01

    In global geodetic solutions vertical rates of site motion are usually estimated relative to the geocenter (center of figure) of the solid earth. The velocity of the geocenter is estimated assuming that the plates are rigid, that the velocities of the plates equal those in NUVEL-1A (DeMets et al. 1990, 1994) and that the uplift, subsidence, and intraplate deformation due to glacial isostatic adjustment is negligible.

  20. Glacial Isostatic Adjustment Observed with VLBI and SLR

    NASA Technical Reports Server (NTRS)

    Argus, D.; Peltier, W.; Watkins, M.

    1999-01-01

    In global geodetic solutions vertical rates of site motion are usually estimated relative to the geocenter (center of figure) of the solid earth. The velocity of the geocenter is estimated assuming that the plates are rigid, that the velocities of the plates equal those in NUVEL-1A (DeMets et al. 1990, 1994) and that the uplift, subsidence, and intraplate deformation due to glacial isostatic adjustment is negligible.

  1. Supersymmetry protected topological phases of isostatic lattices and kagome antiferromagnets

    NASA Astrophysics Data System (ADS)

    Lawler, Michael J.

    2016-10-01

    I generalize the theory of phonon topological band structures of isostatic lattices to frustrated antiferromagnets. I achieve this with a discovery of a many-body supersymmetry (SUSY) in the phonon problem of balls and springs and its connection to local constraints satisfied by ground states. The Witten index of the SUSY model demands the Maxwell-Calladine index of mechanical structures. "Spontaneous supersymmetry breaking" is identified as the need to gap all modes in the bulk to create the topological isostatic lattice state. Since ground states of magnetic systems also satisfy local constraint conditions (such as the vanishing of the total spin on a triangle), I identify a similar SUSY structure for many common models of antiferromagnets including the square, triangluar, kagome, pyrochlore nearest-neighbor antiferromagnets, and the J2=J1/2 square-lattice antiferromagnet. Remarkably, the kagome family of antiferromagnets is the analog of topological isostatic lattices among this collection of models. Thus, a solid-state realization of the theory of phonon topological band structure may be found in frustrated magnetic materials.

  2. The Global University Press

    ERIC Educational Resources Information Center

    Dougherty, Peter J.

    2012-01-01

    The modern world's understanding of American university press has long been shaped by university-press books. American university-press books are good international advertisements for the universities whose logos grace their spines. The growth of transnational scholarship and the expansion of digital communications networks are converging in ways…

  3. Reciprocating pellet press

    DOEpatents

    Jones, Charles W.

    1981-04-07

    A machine for pressing loose powder into pellets using a series of reciprocating motions has an interchangeable punch and die as its only accurately machines parts. The machine reciprocates horizontally between powder receiving and pressing positions. It reciprocates vertically to press, strip and release a pellet.

  4. The Global University Press

    ERIC Educational Resources Information Center

    Dougherty, Peter J.

    2012-01-01

    The modern world's understanding of American university press has long been shaped by university-press books. American university-press books are good international advertisements for the universities whose logos grace their spines. The growth of transnational scholarship and the expansion of digital communications networks are converging in ways…

  5. On the residual isostatic topography effect in the gravimetric Moho determination

    NASA Astrophysics Data System (ADS)

    Bagherbandi, Mohammad; Tenzer, Robert; Sjöberg, Lars E.; Abrehdary, Majid

    2015-01-01

    In classical isostatic models, a uniform crustal density is typically assumed, while disregarding the crustal density heterogeneities. This assumption, however, yields large errors in the Moho geometry determined from gravity data, because the actual topography is not fully isostatically compensated. Moreover, the sub-crustal density structures and additional geodynamic processes contribute to the overall isostatic balance. In this study we investigate the effects of unmodelled density structures and geodynamic processes on the gravity anomaly and the Moho geometry. For this purpose, we define the residual isostatic topography as the difference between actual topography and isostatic topography, which is computed based on utilizing the Vening Meinesz-Moritz isostatic theory. We show that the isostatic gravity bias due to disagreement between the actual and isostatically compensated topography varies between -382 and 596 mGal. This gravity bias corresponds to the Moho correction term of -16 to 25 km. Numerical results reveal that the application of this Moho correction to the gravimetrically determined Moho depths significantly improves the RMS fit of our result with some published global seismic and gravimetric Moho models. We also demonstrate that the isostatic equilibrium at long-to-medium wavelengths (up to degree of about 40) is mainly controlled by a variable Moho depth, while the topographic mass balance at a higher-frequency spectrum is mainly attained by a variable crustal density.

  6. An isostatic model for the Tharsis province, Mars

    NASA Technical Reports Server (NTRS)

    Sleep, N. H.; Phillips, R. J.

    1979-01-01

    A crust-upper mantle configuration is proposed for the Tharsis province of Mars which is isostatic and satisfies the observed gravity data. The model is that of a low density upper mantle compensating loads at both the surface and crust-mantle boundary. Solutions are found for lithospheric thickness greater than about 300 km, for which the stress differences are less than 750 bars. This model for Tharsis is similar to the compensation mechanism under the Basin and Range province of the western United States. These provinces also compare favorably in the sense that they are both elevated regions of extensional tectonics and extensive volcanism.

  7. A study of Glacial Isostatic Adjustment in Greenland

    NASA Astrophysics Data System (ADS)

    Nielsen, Jens Emil; Sandberg Sørensen, Louise; Adalgeirsdottir, Gudfinna; Spada, Giorgio

    2010-05-01

    Glacial isostatic adjustment (GIA) is the viscoelastic response of the Earth caused by changes in ice loads during glaciations and deglaciations. Knowledge of the GIA signal is particularly important in cryospheric applications of satellite gravimetry and altimetry, where the origin of the observed changes must be separated into past and present response. Modeling the present-day GIA signal must include knowledge of both the ice loading history and the Earth's rheology. Neither of these models are well constrained in Greenland, and hence the GIA estimates here are uncertain. In this paper we implement a loading history of the Greenland Ice Sheet derived from the ice sheet model SICOPOLIS, and we study the present-day gravity changes and vertical crustal motion derived from using this ice history. The results are compared with those derived from the widely used ICE-5G ice history. For calculation of present day GIA signal, we assume the Earth's rheology to be a simplified version of the VM2 Earth model. The calculated GIA signal in Greenland, derived from the two ice loading histories are compared with geodetic measurements of vertical crustal motion from GPS time series and with repeated gravity measurements in Greenland. The free code SELEN is used for calculating the effects of the Earth model and different ice loading histories. This study is performed within the Working Group 4 of the ESF COST Action ES0701 "Improved constraints on models of Glacial Isostatic Adjustment".

  8. Origins of topological bulk modes in isostatic lattices

    NASA Astrophysics Data System (ADS)

    Rocklin, D. Zeb; Chen, Bryan; Falk, Martin; Lubensky, Tom; Vitelli, Vincenzo

    2015-03-01

    Mechanical lattices under periodic boundary conditions with coordination z = 2 d , where d is the spatial dimensionality, and with a gapped phonon spectrum at all wavenumbers not equal to zero are isostatic. When cut, these lattices with N sites in two dimensions necessarily have of order N 1 / 2 zero modes on their boundaries. Recently, Kane and Lubensky showed that these systems can be described by a super-symmetric Hamiltonian analogous to that of the Su-Schrieffer model for polyacetylene and they identified a topological invariant, the topological polarization, that determines on which edges zero modes lie in finite systems. We show that a family of two-dimensional four-site-per-unit-cell isostatic lattices possess topologically protected bulk zero modes. These ``Weyl modes'' are novel, tunable low-energy mechanisms of the mechanical lattice. They are the analogs of the zero-energy electronic modes of topological semimetals. We discuss how adjusting the lattice parameters induces Weyl modes and alters their wavevectors (generally incommensurate with the lattice) and how they can transport zero modes from one edge to an opposite one as surface wavenumber varies. An accompanying talk discusses the novel dynamical properties of the system.

  9. Glacial Isostatic Adjustment and Contemporary Sea Level Rise: An Overview

    NASA Astrophysics Data System (ADS)

    Spada, Giorgio

    2017-01-01

    Glacial isostatic adjustment (GIA) encompasses a suite of geophysical phenomena accompanying the waxing and waning of continental-scale ice sheets. These involve the solid Earth, the oceans and the cryosphere both on short (decade to century) and on long (millennia) timescales. In the framework of contemporary sea-level change, the role of GIA is particular. In fact, among the processes significantly contributing to contemporary sea-level change, GIA is the only one for which deformational, gravitational and rotational effects are simultaneously operating, and for which the rheology of the solid Earth is essential. Here, I review the basic elements of the GIA theory, emphasizing the connections with current sea-level changes observed by tide gauges and altimetry. This purpose is met discussing the nature of the "sea-level equation" (SLE), which represents the basis for modeling the sea-level variations of glacial isostatic origin, also giving access to a full set of geodetic variations associated with GIA. Here, the SLE is employed to characterize the remarkable geographical variability of the GIA-induced sea-level variations, which are often expressed in terms of "fingerprints". Using harmonic analysis, the spatial variability of the GIA fingerprints is compared to that of other components of contemporary sea-level change. In closing, some attention is devoted to the importance of the "GIA corrections" in the context of modern sea-level observations, based on tide gauges or satellite altimeters.

  10. Linking Mid-Atlantic Landscapes to Glacio-Isostatic Adjustments

    NASA Astrophysics Data System (ADS)

    Pavich, M. J.

    2006-12-01

    Mid-Atlantic landscape studies have traditionally focused on the physiographic contrasts of landforms and their genetic processes. The strong contrasts of mountain, piedmont and coastal plain have dominated thinking about landscape history (Davis) and dynamic equilibrium (Hack). Timescales in these conceptual models are >106 years. Recent research on bedrock channel incision and uplift of late Pleistocene estuarine and marine deposits shows that significant landscape adjustments south of the glacial border occur on timescales of <105 years. Optically stimulated luminescence (OSL) dates and cosmogenic isotope exposure dating indicate that between ~36ka and ~10ka, uplift occurred at ~1m/ky and bedrock channels incised at ~0.6m/ky in the vicinity of Chesapeake Bay. These high rates, particularly compared to southern Appalachian landscapes in long- term isostatic equilibrium, are linked to the glacio-isostatic adjustments (GIA) created by the Laurentide ice of the latest glacial cycle. Recognition of major landform adjustments due to forebulge uplift and subsidence at this timescale requires a fundamental reassessment of Appalachian landscape models. Geomorphic and stratigraphic studies can provide important constraints on GIA models. The role of GIA in the mid-Atlantic region also provides information about ongoing landscape changes, particularly the potential for future subsidence.

  11. Dry pressing technical ceramics

    SciTech Connect

    Lewis, W.A. Jr.

    1996-04-01

    Dry pressing of technical ceramics is a fundamental method of producing high-quality ceramic components. The goals of dry pressing technical ceramics are uniform compact size and green density, consistent part-to-part green density and defect-free compact. Dry pressing is the axial compaction of loosely granulated dry ceramic powders (< 3% free moisture) within a die/punch arrangement. The powder, under pressure, conforms to the specific shape of the punch faces and die. Powder compaction occurs within a rigid-walled die and usually between a top and bottom punch. Press configurations include anvil, rotary, multiple-punch and multiple-action.

  12. University Presses: Problems and Prospects.

    ERIC Educational Resources Information Center

    Meeker, Robert B.

    Historical information on university presses and their problems are considered. University presses in the United States have their roots in 15th century England when the Oxford University Press was established in 1478. The first U.S. press to use the term "university press" was Cornell University; the press operated from 1869 until it…

  13. High School Press Pressures.

    ERIC Educational Resources Information Center

    Rogers, Luella P.

    History shows that the high school press suffers through cycles that reflect economic factors and cultural climates within communities, states, and the nation. The direction of that cycle in the 1960s and early 1970s was toward more open, free-flowing information by a vigorous student press, but those economic and cultural signs now are pointing…

  14. The Greenwood School Press.

    ERIC Educational Resources Information Center

    Lamb, Jane

    1984-01-01

    A turn-of-the-century printing press motivates elementary students to write. Children write, edit, and print their own stories on the Greenwood School Press. This self-supporting enterprise introduces children to various aspects of writing and producing literature. (DF)

  15. Press Councils in Canada.

    ERIC Educational Resources Information Center

    Reddick, David B.

    Established in the early 1970s to respond to complaints about and from the media, the four press councils in Canada (the Alberta, Ontario, Quebec, and Windsor Press Councils) have been accepted, but not overwhelmingly so by either newspapers or the public. The success and acceptability of the councils seems to be related to the kinds of complaints…

  16. Lyndon Johnson's Press Conferences.

    ERIC Educational Resources Information Center

    Cooper, Stephen

    Because President Lyndon Johnson understood well the publicity value of the American news media, he sought to exploit them. He saw reporters as "torch bearers" for his programs and policies and used the presidential press conference chiefly for promotional purposes. Although he met with reporters often, his press conferences were usually…

  17. High School Press Pressures.

    ERIC Educational Resources Information Center

    Rogers, Luella P.

    History shows that the high school press suffers through cycles that reflect economic factors and cultural climates within communities, states, and the nation. The direction of that cycle in the 1960s and early 1970s was toward more open, free-flowing information by a vigorous student press, but those economic and cultural signs now are pointing…

  18. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, moderates a press conference with NASA Administrator Michael Griffin Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  19. Press Relations: Carter's Example.

    ERIC Educational Resources Information Center

    Kindsvatter, Peter S.

    Although different philosophies may motivate presidential-press relations, causing frequent friction or adversity, there is nevertheless a strong degree of cooperation and collaboration between the press and a president of the United States. This interdependence has been particularly evident in recent administrations, and it progresses…

  20. The Greenwood School Press.

    ERIC Educational Resources Information Center

    Lamb, Jane

    1984-01-01

    A turn-of-the-century printing press motivates elementary students to write. Children write, edit, and print their own stories on the Greenwood School Press. This self-supporting enterprise introduces children to various aspects of writing and producing literature. (DF)

  1. Evidence for Anomalous Dynamic Heterogeneities in Isostatic Supercooled Liquids

    NASA Astrophysics Data System (ADS)

    Micoulaut, M.; Bauchy, M.

    2017-04-01

    Upon cooling, the dynamics of supercooled liquids exhibits a growing transient spatial distribution of relaxation times that is known as dynamic heterogeneities. The relationship between this now well-established crucial feature of the glass transition and some underlying liquid properties remains challenging and elusive in many respects. Here we report on computer simulations of liquids with a changing network structure (densified silicates), and show that there is a deep and important link between the mechanical nature characterized by topological constraints and the spatial extent of such fluctuations. This is not only revealed by a maximum in the dynamic correlation length ξ4 for fluctuations when the liquid becomes isostatically rigid, but also by a contraction of the volume of relaxing structural correlations upon the onset of stressed rigidity.

  2. Space-geodetic constraints on glacial isostatic adjustment in Fennoscandia.

    PubMed

    Milne, G A; Davis, J L; Mitrovica, J X; Scherneck, H G; Johansson, J M; Vermeer, M; Koivula, H

    2001-03-23

    Analysis of Global Positioning System (GPS) data demonstrates that ongoing three-dimensional crustal deformation in Fennoscandia is dominated by glacial isostatic adjustment. Our comparison of these GPS observations with numerical predictions yields an Earth model that satisfies independent geologic constraints and bounds both the average viscosity in the upper mantle (5 x 10(20) to 1 x 10(21) pascal seconds) and the elastic thickness of the lithosphere (90 to 170 kilometers). We combined GPS-derived radial motions with Fennoscandian tide gauge records to estimate a regional sea surface rise of 2.1 +/- 0.3 mm/year. Furthermore, ongoing horizontal tectonic motions greater than approximately 1 mm/year are ruled out on the basis of the GPS-derived three-dimensional crustal velocity field.

  3. The isostatic state of the lunar Apennines and regional surroundings

    NASA Technical Reports Server (NTRS)

    Ferrari, A. J.; Sjogren, W. L.; Phillips, R. J.; Nelson, D. L.

    1978-01-01

    High-resolution gravity and topography data taken over the Apennine Mountains have been used to compute their isostatic state. Results show that the Apennines are uncompensated; thus this state implies that the lunar crust and upper mantle have been strong enough over 3.9 b.y. to support the load exerted by this topographic excess. The Apennines produce a maximum shear stress of 60 bars at a depth of 60 km. A lower bound on the lunar crustal viscosity of 10 to the 27th power P is calculated on the basis of the assumption of a 10% relaxation over 3.9 b.y. Studies of a broad negative regional anomaly located between Maria Serenitatis and Imbrium necessitate a locally thicker crust to satisfy the observed data. This anomaly may have been produced by a lateral transport of crustal material from beneath the giant impact basins as a result of rebound at the crust-mantle interface.

  4. Segmentation of the Andean margin by isostatic models and gradients

    NASA Astrophysics Data System (ADS)

    Schaller, T.; Andersen, J.; Götze, H.-J.; Koproch, N.; Schmidt, S.; Sobiesiak, M.; Splettstößer, S.

    2015-04-01

    The gravity gradients of the South American continental margin are the highest on Earth. These gradients are proxies for the strong horizontal stresses due to the convergent movement of the Nazca plate and the overriding South American plate. The frequently occurring large earthquakes in this zone suggest a correlation of gravity anomalies and seismogenic structures which is the major target of our research. Numerical analyses of the Central Andean gravity field were conducted using different techniques such as isostatic calculations, inversion and edge detection while varying the key parameters of the respective methods. Also, a constrained 3D density model was built through forward modelling of the terrestrial Bouguer anomaly. The results point out that a Vening-Meinesz model with a rigidity of 1023 Nm fits optimally the isostatic behaviour of the Central Andes. For numerical inversion the following parameters provided best results: density contrasts between 430-500 kg/m3, compensation depths of 30-40 km and a 400/300-km-wavelength filter. Moho depths obtained from the different methods agree reasonably well in the continental and oceanic area but defer the most in the transition zone between the two. In this coastal area, north-south segmentation of the residual fields is evident. The respective gravity defined segments correspond well with the extent of large earthquake rupture planes in the southern part of the investigation area. We propose that this segmentation is reflected by changing thicknesses of high density crustal bodies modelled in the 3D density model. These old batholiths fit extremely well to high-velocity domains from seismic tomography. Further seismic asperity structures also display a good correlation with different features of the residual fields.

  5. Design and analysis of isostatic mounts on a spaceborne lightweight primary mirror

    NASA Astrophysics Data System (ADS)

    Chan, C. Y.; Chen, Y. C.; Chang, S. T.; Huang, T. M.; Hsu, M. Y.

    2013-09-01

    The paper is aimed at obtaining the optimum isostatic mount configuration for a ZERODUR® primary mirror with a predesigned lightweight configuration on the back for a space Cassegrain telescope. The finite element analysis and Zernike polynomial fitting based on the Taguchi method are applied to the whole optimization process. Under the integrated optomechanical analysis, three isostatic mounts are bonded to the center of gravity of the mirror. Geometrical control factors and levels have been selected to minimize the optical aberrations under self-weight loading. The optimum isostatic mount with the least induced astigmatism value is finally attained under the Taguchi method.

  6. Expedition 52 Press Conference

    NASA Image and Video Library

    2017-07-10

    Expedition 52 flight engineer Randy Bresnik of NASA answers a reporter's question during a crew press conference at the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  7. STS-135 Press Conference

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060448 (30 June 2011) --- NASA astronaut Rex Walheim, STS-135 mission specialist, fields a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA

  8. Expedition 52 Press Conference

    NASA Image and Video Library

    2017-07-10

    Expedition 52 flight engineer Sergey Ryazanskiy of Roscosmos answers a reporter's question during a crew press conference at the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  9. STS-135 Press Briefings

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060720 (30 June 2011) -- STS-135 lead flight director Kwatsi Alibaruho responds to a question from a reporter during a mission overview press conference at NASA's Johnson Space Center. Photo credit: NASA

  10. STS-135 Press Conference

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060450 (30 June 2011) --- NASA astronaut Rex Walheim, STS-135 mission specialist, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA

  11. Expedition 32 Press Conference

    NASA Image and Video Library

    2012-07-13

    Quarantined Expedition 32 Canadian backup crewmember Chris Hadfield answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Friday, July 13, 2012 in Baikonur, Kazakhstan. Photo Credit (NASA/Carla Cioffi)

  12. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028493 (24 March 2011) --- NASA astronaut Mark Kelly, STS-134 commander, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  13. STS-135 Press Conference

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060415 (30 June 2011) --- NASA astronaut Sandy Magnus, STS-135 mission specialist, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA

  14. STS-135 Press Conference

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060445 (30 June 2011) --- NASA astronaut Sandy Magnus, STS-135 mission specialist, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA

  15. Expedition 52 Press Conference

    NASA Image and Video Library

    2017-07-10

    Expedition 52 flight engineer Paolo Nespoli of ESA answers a reporter's question during a crew press conference at the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  16. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028492 (24 March 2011) --- NASA astronaut Greg Chamitoff, STS-134 mission specialist, fields a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  17. STS-135 Press Conference

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060413 (30 June 2011) --- NASA astronaut Chris Ferguson, STS-135 commander, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA

  18. Expedition 6 Press Conference

    NASA Image and Video Library

    2003-05-05

    Expedition 6 Commander Ken Bowersox, left and NASA International Space Station Science Officer Don Pettit speak during a press conference at the Gagarin Cosmonaut Training Center in Star City, Russia, Thursday, May 6, 2003. Photo Credit: (NASA/Bill Ingalls)

  19. Expedition 6 Press Conference

    NASA Image and Video Library

    2003-05-05

    Expedition 6 International Space Station Science Officer Don Pettit speaks during a press conference at the Gagarin Cosmonaut Training Center in Star City, Russia, Thursday, May 6, 2003. Photo Credit: (NASA/Bill Ingalls)

  20. STS-132 press conference

    NASA Image and Video Library

    2010-05-03

    JSC2010-E-063790 (3 May 2010) --- NASA astronaut Garrett Reisman, STS-132 mission specialist, fields a question from a reporter during an STS-132 preflight press conference at NASA's Johnson Space Center.

  1. STS-132 press conference

    NASA Image and Video Library

    2010-05-03

    JSC2010-E-063807 (3 May 2010) --- NASA astronaut Mike Good, STS-132 mission specialist, responds to a question from a reporter during an STS-132 preflight press conference at NASA's Johnson Space Center.

  2. STS-131 press conference

    NASA Image and Video Library

    2010-03-09

    JSC2010-E-038795 (9 March 2010) --- NASA astronaut Stephanie Wilson, STS-131 mission specialist, fields a question from a reporter during an STS-131 preflight press conference at NASA's Johnson Space Center.

  3. STS-132 press conference

    NASA Image and Video Library

    2010-05-03

    JSC2010-E-063799 (3 May 2010) --- NASA astronaut Steve Bowen, STS-132 mission specialist, fields a question from a reporter during an STS-132 preflight press conference at NASA's Johnson Space Center.

  4. STS-132 press conference

    NASA Image and Video Library

    2010-05-03

    JSC2010-E-063808 (3 May 2010) --- NASA astronaut Garrett Reisman, STS-132 mission specialist, responds to a question from a reporter during an STS-132 preflight press conference at NASA's Johnson Space Center.

  5. STS-131 press conference

    NASA Image and Video Library

    2010-03-09

    JSC2010-E-038797 (9 March 2010) --- NASA astronaut Rick Mastracchio, STS-131 mission specialist, responds to a question from a reporter during an STS-131 preflight press conference at NASA's Johnson Space Center.

  6. STS-132 press conference

    NASA Image and Video Library

    2010-05-03

    JSC2010-E-063797 (3 May 2010) --- NASA astronaut Steve Bowen, STS-132 mission specialist, fields a question from a reporter during an STS-132 preflight press conference at NASA's Johnson Space Center.

  7. STS-131 press conference

    NASA Image and Video Library

    2010-03-09

    JSC2010-E-038794 (9 March 2010) --- NASA astronaut Alan Poindexter, STS-131 commander, responds to a question from a reporter during an STS-131 preflight press conference at NASA's Johnson Space Center.

  8. STS-135 Press Conference

    NASA Image and Video Library

    2011-06-30

    JSC2011-E-060439 (30 June 2011) --- NASA astronaut Chris Ferguson, STS-135 commander, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA

  9. STS-125 Press Conference

    NASA Image and Video Library

    2009-04-23

    JSC2009-E-087199 (23 April 2009) --- Astronaut Michael Good, STS-125 mission specialist, responds to a question from a reporter during a STS-125 preflight press briefing at NASA's Johnson Space Center.

  10. STS-131 press conference

    NASA Image and Video Library

    2010-03-09

    JSC2010-E-038799 (9 March 2010) --- NASA astronaut Clayton Anderson, STS-131 mission specialist, responds to a question from a reporter during an STS-131 preflight press conference at NASA's Johnson Space Center.

  11. Expedition 19 Press Conference

    NASA Image and Video Library

    2009-03-24

    Expedition 19 Flight Engineer Michael R. Barratt smiles at his family from a quarantined glass room after a press conference on Wednesday, March 25, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  12. EPOXI Mission Press Conference

    NASA Image and Video Library

    2010-11-18

    Michael A'Hearn, EPOXI Principal Investigator, University of Maryland, holds a plastic bottle containing ice to illustrate a point during a press conference, Thursday, Nov. 18, 2010, at NASA Headquarters in Washington. The press conference was held to discuss the Nov. 4 successful flyby of Comet Hartley 2 by NASA's EPOXI Mission Spacecraft. Images from the flyby provided scientists the most extensive observations of a comet in history. Photo Credit: (NASA/Paul E. Alers)

  13. EPOXI Mission Press Conference

    NASA Image and Video Library

    2010-11-18

    Dr. James Green, Director of Planetary Science, NASA Headquarters, at podium, speaks during a press conference, Thursday, Nov. 18, 2010, at NASA Headquarters in Washington. The press conference was held to discuss the Nov. 4 successful flyby of Comet Hartley 2 by NASA's EPOXI Mission Spacecraft. Images from the flyby provided scientists the most extensive observations of a comet in history. Photo Credit: (NASA/Paul E. Alers)

  14. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    NASA Administrator Michael Griffin, seated left, Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, are seen during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, far left, moderates the program. Photo Credit (NASA/Bill Ingalls)

  15. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    Dwayne Brown, NASA Public Affairs Officer, takes a question from a member of the press on theupcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  16. Elasticity and response in nearly isostatic periodic lattices

    NASA Astrophysics Data System (ADS)

    Mao, Xiaoming

    2010-03-01

    The emergence of rigidity, especially when complicated by disorder, is a subtle phenomenon that occurs in a wide variety of systems. Isostatic lattices, such as the d-dimensional hypercubic lattice and the 2d kagome lattice with nearest neighbor springs, in which the number of contacts z per particle in d-dimensions is equal to zc=2d, provide simple models, which inform us about systems like jammed solids, glasses, colloidal suspensions, and foams, for the analytic study of general features of the onset of rigidity. Isostatic lattices are marginally stable and may exhibit a non-extensive number of zero modes that can be removed by the addition of bond-bending forces, negative pressure, or additional springs. We use the coherent potential approximation (CPA) to study the onset of rigidity induced by randomly adding next-nearest-neighbor (NNN) bonds to the square and kagome lattices, and we relate the results to the random packings of frictionless spheres at point J. We identify a characteristic frequency scale &*circ; and length scale l^* and show that within the CPA they scale, respectively, as δz and δz-1 where δz = z - zc. This result, which replicates results near jamming, is a result of strongly nonaffine elastic response at small δz. We find that the frequency-dependent effective NNN spring constant κ obeys a scaling relation κ( φ)/κ(0) = f(φ/φ*), where κ( 0 ) ˜(δz)^2. In the square lattice the shear modulus G(φ) is equal to κ( φ), whereas in the kagome lattice, the shear modulus G0 at δz = 0 is finite and proportional to the spring constant of nearest-neighbor bonds, and G(φ) -G0˜κ( φ), Finally, we show that the CPA exhibits strong phonon scattering for φ>&*circ; indicating a Ioffe-Regel limit for heat transport. This work was supported by NSF DMR 0804900.

  17. Earth's isostatic gravity anomaly field: Contributions to National Geodetic Satellite Program

    NASA Technical Reports Server (NTRS)

    Khan, M. A.

    1973-01-01

    On the assumption that the compensation for the topographic load is achieved in the manner of Airy-Heiskenenan hypothesis at a compensation depth of 30 kilometers, the spherical harmonic coefficients of the isostatic reduction potential U are computed. The degree power spectra of these coefficients are compared with the power spectra of the isostatic reduction coefficients given by Uotila. Results are presented in tabular form.

  18. Glacial Isostatic Adjustment - a hot topic in cold regions

    NASA Astrophysics Data System (ADS)

    Whitehouse, Pippa

    2016-04-01

    Glacial Isostatic Adjustment (GIA) modelling tackles the classic geodynamical problem of determining the solid Earth response to surface load changes by ice and ocean water whilst at the same time solving for the gravitationally-consistent redistribution of ice sheet meltwater across the global ocean. Understanding this process is important for quantifying both present-day ice mass balance and the response of ice sheets to past and future climatic change. The two fundamental unknowns in this problem are (i) the rheology of the solid Earth, and (ii) the history of global ice sheet change. In this talk I will discuss the myriad of approaches that are used to constrain these two components. In particular, I will focus on Antarctica, where the presence of a continuously-evolving ice sheet, situated on top of one of the most rheologically-diverse regions of the planet, provides us with a challenge that can only be resolved by drawing on knowledge from across the fields of geodynamics, glaciology, geology, geodesy and seismology.

  19. Inverting Glacial Isostatic Adjustment beyond linear viscoelasticity using Burgers rheology

    NASA Astrophysics Data System (ADS)

    Caron, L.; Greff-Lefftz, M.; Fleitout, L.; Metivier, L.; Rouby, H.

    2014-12-01

    In Glacial Isostatic Adjustment (GIA) inverse modeling, the usual assumption for the mantle rheology is the Maxwell model, which exhibits constant viscosity over time. However, mineral physics experiments and post-seismic observations show evidence of a transient component in the deformation of the shallow mantle, with a short-term viscosity lower than the long-term one. In these studies, the resulting rheology is modeled by a Burgers material: such rheology is indeed expected as the mantle is a mixture of materials with different viscosities. We propose to apply this rheology for the whole viscoelastic mantle, and, using a Bayesian MCMC inverse formalism for GIA during the last glacial cycle, study its impact on estimations of viscosity values, elastic thickness of the lithosphere, and ice distribution. To perform this inversion, we use a global dataset of sea level records, the geological constraints of ice-sheet margins, and present-day GPS data as well as satellite gravimetry. Our ambition is to present not only the best fitting model, but also the range of possible solutions (within the explored space of parameters) with their respective probability of explaining the data. Our first results indicate that compared to the Maxwell models, the Burgers models involve a larger lower mantle viscosity and thicker ice over Fennoscandia and Canada.

  20. Assessment of Glacial Isostatic Adjustment in Greenland using GPS

    NASA Astrophysics Data System (ADS)

    Khan, S. A.; Bevis, M. G.; Sasgen, I.; van Dam, T. M.; Wahr, J. M.; Wouters, B.; Bamber, J. L.; Willis, M. J.; Knudsen, P.; Helm, V.; Kuipers Munneke, P.; Muresan, I. S.

    2015-12-01

    The Greenland GPS network (GNET) was constructed to provide a new means to assess viscoelastic and elastic adjustments driven by past and present-day changes in ice mass. Here we assess existing glacial isostatic adjustments (GIA) predictions by analysing 1995-2015 data from 61 continuous GPS receivers located along the margin of the Greenland ice sheet. Since GPS receivers measure both the GIA and elastic signals, we isolate GIA, by removing the elastic adjustments of the lithosphere due to present-day mass changes using high-resolution fields of ice surface elevation change derived from satellite and airborne altimetry measurements (ERS1/2, ICESat, ATM, ENVISAT, and CryoSat-2). For most GPS stations, our observed GIA rates contradict GIA predictions; particularly, we find huge uplift rates in southeast Greenland of up to 14 mm/yr while models predict rates of 0-2 mm/yr. Our results suggest possible improvements of GIA predictions, and hence of the poorly constrained ice load history and Earth structure models for Greenland.

  1. Fabrication and properties of (TbxY1-x)3Al5O12 transparent ceramics by hot isostatic pressing

    NASA Astrophysics Data System (ADS)

    Duan, Pingping; Liu, Peng; Xu, Xiaodong; Wang, Wei; Wan, Zhong; Zhang, Shouyi; Wang, Yinzhen; Zhang, Jian

    2017-10-01

    (TbxY1-x)3Al5O12 (x = 0.2, 0.5, 0.8) transparent ceramics were synthesized by a solid-state reaction and HIP. All the samples were pre-sintered at 1650 °C for 4 h in a muffle and later HIPed at 1650 °C for 3 h. (Tb0.2Y0.8)3Al5O12 transparent ceramics exhibit best microstructure with an average grain size of approximately 5.22 μm and optical transmittance of over 65% in the region of 500-1600 nm. Additionally, average grain sizes of all the samples are less than 10 μm. XRD scanning patterns indicate that only the (Tb0.8Y0.2)3Al5O12 samples have little secondary phases.

  2. Microstructural anomalies in hot-isostatic pressed U–10wt.% Mo fuel plates with Zr diffusion barrier

    SciTech Connect

    Park, Y.; Eriksson, N.; Keiser, D. D.; Jue, J.; Rabin, B.; Moore, G.; Sohn, Y. H.

    2015-05-01

    Microstructural anomalies in the co-rolled-and-HIP'ed U–10 wt.% Mo (U10Mo) metallic fuel plate with Zr diffusion barrier assembly were examined as a function of HIP temperature (from 520 to 580 °C) and duration (45, 60, 90, 180 and 345 min) by scanning and transmission electron microscopy. The anomalies observed in this study are carbide/oxide inclusions within the U10Mo fuel alloy, and regions of limited interaction between the U10Mo alloy and Zr barrier, frequently associated with carbide/oxide inclusions. In the U10Mo alloy, the cF8, Fm3m (225) UC phase (a=4.955 Å) and cF12, Fm3m (225) UO2 phase (a=5.467 Å) were observed throughout the U10Mo alloy with an approximate volume percent of 0.5 to 1.8. The volume percent of the UC–UO2 inclusions within the U10Mo alloy did not change as functions of HIP temperature and time. These inclusion phases, located near the surface of the U10Mo alloy, were frequently observed to impede the development of interdiffusion and reaction between the U10Mo alloy and Zr diffusion barrier. The regions of limited interaction between the U10Mo and Zr barrier decreased with an increase in HIP temperature, however no noticeable trend was observed with an increase in HIP duration at constant temperature of 560 °C.

  3. Hot Isostatic Pressing/Heat Treatment of Cast Superalloy AF2-1DA, Radial Turbine Wheels.

    DTIC Science & Technology

    1980-06-01

    showing typical 19 shrinkage porosity Mag: 400X Etch: Electrolytic oxalic acid 10 Microstructure of HIPped AF2-1DA alloy 29 Mag: 400X Etch...Electrolytic oxalic acid 11 Microstructure of HIPped AF2-1DA alloy note 30 void formations form incipient melting after 2250OF hip Mag: 400X Etch: Electrolytic... oxalic acid V a.w LIST OF ILLUSTRATIONS (Continued) Figure Title Page 12 Microstructure of HIPped AF2-1DA showing effects 31 of solution heat

  4. The Manufacture of W-UO2 Fuel Elements for NTP Using the Hot Isostatic Pressing Consolidation Process

    NASA Technical Reports Server (NTRS)

    Broadway, Jeramie; Hickman, Robert; Mireles, Omar

    2012-01-01

    NTP is attractive for space exploration because: (1) Higher Isp than traditional chemical rockets (2)Shorter trip times (3) Reduced propellant mass (4) Increased payload. Lack of qualified fuel material is a key risk (cost, schedule, and performance). Development of stable fuel form is a critical path, long lead activity. Goals of this project are: Mature CERMET and Graphite based fuel materials and Develop and demonstrate critical technologies and capabilities.

  5. A Wavelet-Based Assessment of Topographic-Isostatic Reductions for GOCE Gravity Gradients

    NASA Astrophysics Data System (ADS)

    Grombein, Thomas; Luo, Xiaoguang; Seitz, Kurt; Heck, Bernhard

    2014-07-01

    Gravity gradient measurements from ESA's satellite mission Gravity field and steady-state Ocean Circulation Explorer (GOCE) contain significant high- and mid-frequency signal components, which are primarily caused by the attraction of the Earth's topographic and isostatic masses. In order to mitigate the resulting numerical instability of a harmonic downward continuation, the observed gradients can be smoothed with respect to topographic-isostatic effects using a remove-compute-restore technique. For this reason, topographic-isostatic reductions are calculated by forward modeling that employs the advanced Rock-Water-Ice methodology. The basis of this approach is a three-layer decomposition of the topography with variable density values and a modified Airy-Heiskanen isostatic concept incorporating a depth model of the Mohorovičić discontinuity. Moreover, tesseroid bodies are utilized for mass discretization and arranged on an ellipsoidal reference surface. To evaluate the degree of smoothing via topographic-isostatic reduction of GOCE gravity gradients, a wavelet-based assessment is presented in this paper and compared with statistical inferences in the space domain. Using the Morlet wavelet, continuous wavelet transforms are applied to measured GOCE gravity gradients before and after reducing topographic-isostatic signals. By analyzing a representative data set in the Himalayan region, an employment of the reductions leads to significantly smoothed gradients. In addition, smoothing effects that are invisible in the space domain can be detected in wavelet scalograms, making a wavelet-based spectral analysis a powerful tool.

  6. A Guide to Press Relations.

    ERIC Educational Resources Information Center

    Fibre Box Association, Chicago, IL.

    Stressing that a positive press-relations program can be extremely helpful to businesses, this publication offers suggestions for establishing press contacts, preparing press releases, holding press conferences, illustrating a story, preparing materials for use in radio and television broadcasts, and developing policies to be followed in emergency…

  7. Worldwide complete spherical Bouguer and isostatic anomaly maps

    NASA Astrophysics Data System (ADS)

    Bonvalot, S.; Balmino, G.; Briais, A.; Peyrefitte, A.; Vales, N.; Biancale, R.; Gabalda, G.; Reinquin, F.

    2011-12-01

    We present here a set of digital maps of the Earth's gravity anomalies (surface "free air", Bouguer and isostatic), computed at Bureau Gravimetric International (BGI) as a contribution to the Global Geodetic Observing Systems (GGOS) and to the global geophysical maps published by the Commission for the Geological Map of the World (CGMW). The free air and Bouguer anomaly concept is extensively used in geophysical interpretation to investigate the density distributions in the Earth's interior. Complete Bouguer anomalies (including terrain effects) are usually computed at regional scales by integrating the gravity attraction of topography elements over and beyond a given area (under planar or spherical approximations). Here, we developed and applied a worldwide spherical approach aimed to provide a set of homogeneous and high resolution gravity anomaly maps and grids computed at the Earth's surface, taking into account a realistic Earth model and reconciling geophysical and geodetic definitions of gravity anomalies. This first version (1.0) has been computed by spherical harmonics analysis / synthesis of the Earth's topography-bathymetry up to degree 10800. The detailed theory of the spherical harmonics approach is given in Balmino et al., (Journal of Geodesy, submitted). The Bouguer and terrain corrections have thus been computed in spherical geometry at 1'x1' resolution using the ETOPO1 topography/bathymetry, ice surface and bedrock models from the NOAA (National Oceanic and Atmospheric Administration) and taking into account precise characteristics (boundaries and densities) of major lakes, inner seas, polar caps and of land areas below sea level. Isostatic corrections have been computed according to the Airy Heiskanen model in spherical geometry for a constant depth of compensation of 30km. The gravity information given here is provided by the Earth Geopotential Model (EGM2008), developed at degree 2160 by the National Geospatial Intelligence Agency (NGA) (Pavlis

  8. Post Launch Press Conference

    NASA Image and Video Library

    2014-12-05

    In the Kennedy Space Center’s Press Site auditorium, agency leaders spoke to members of the news media about the successful Orion Flight Test. From left are: Rachel Kraft, of NASA Public Affairs, Bill Gerstenmaier, NASA associate administrator for Human Exploration and Operations, Mark Geyer, Orion program manager, Mike Hawes, Lockheed Martin Orion Program manager, and NASA astronaut Rex Walheim.

  9. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    Kelly Fast, MAVEN program scientist, NASA Headquarters, discusses the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  10. Press Conference - Skylab 3

    NASA Image and Video Library

    1972-08-14

    S72-46699 (19 Jan. 1972) --- Prime crew members of the scheduled second Skylab mission are introduced to the media during a press conference in January 1972 at the Manned Spacecraft Center (MSC). From left to right are astronauts Jack R. Lousma, pilot; Owen K. Garriott, science pilot, and Alan L. Bean, commander. Photo credit: NASA

  11. Defining the University Press

    ERIC Educational Resources Information Center

    Fletcher, Janet

    1978-01-01

    Reports discussion at the annual meeting of the Association of American University Presses (AAUP) on such topics as overproduction, government support, "on demand" publishing, profitability, library photocopying, and selection in library acquisitions, as they relate to the roles of librarians and publishers. (JPF)

  12. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028491 (24 March 2011) --- European Space Agency astronaut Roberto Vittori, STS-134 mission specialist, fields a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  13. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028498 (24 March 2011) --- European Space Agency astronaut Roberto Vittori, STS-134 mission specialist, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  14. Expedition 34 Press Conference

    NASA Image and Video Library

    2012-12-18

    Russian backup crew member Fyodor Yurchikin, right, answers a reporter's question at a press conference held at the Cosmonaut Hotel, on Tuesday, Dec. 18, 2012, in Baikonur, Kazakhstan. Seen next to him are NASA backup crew member Karen Nyberg and Expedition 34/35 Canadian Space Agency astronaut Chris Hadfield. Photo Credit: (NASA/Carla Cioffi)

  15. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028488 (24 March 2011) --- NASA astronaut Greg H. Johnson, STS-134 pilot, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  16. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028490 (24 March 2011) --- NASA astronaut Michael Fincke, STS-134 mission specialist, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  17. STS-134 Press Conference

    NASA Image and Video Library

    2011-03-24

    JSC2011-E-028496 (24 March 2011) --- NASA astronaut Andrew Feustel, STS-134 mission specialist, responds to a question from a reporter during a preflight press conference at NASA's Johnson Space Center. Photo credit: NASA or National Aeronautics and Space Administration

  18. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 NASA Flight Engineer Mike Fossum, left, and Soyuz Commander Sergei Volkov of Russia share a laugh during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  19. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 Soyuz Commander Anton Shkaplerov answers a reporter’s question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Saturday, Nov. 12, 2011. The mission is set to launch November 14 from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  20. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 NASA Flight Engineer Mike Fossum, speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  1. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 NASA Flight Engineer Mike Fossum speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  2. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 NASA Flight Engineer Mike Fossum, left, and Soyuz Commander Sergei Volkov of Russia are seen during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  3. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 backup crew members NASA Flight Engineer Joseph Acaba, far left, Russian Soyuz Commander Gennady Padalka, center, and Russian Flight Engineer Sergei Revin are seen at a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Saturday, Nov. 12, 2011. Photo Credit: (NASA/Carla Cioffi)

  4. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 NASA Flight Engineer Dan Burbank answers a reporter’s question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Saturday, Nov. 12, 2011. The launch of the Soyuz spacecraft with Expedition 29 NASA Flight Engineer Dan Burbank, Soyuz Commander Anton Shkaplerov and Flight Engineer Anatoly Ivanishin is scheduled for November 14. Photo Credit: (NASA/Carla Cioffi)

  5. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 NASA backup Flight Engineer Don Pettit looks on during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  6. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 Soyuz Commander Sergei Volkov of Russia speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 7, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  7. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 NASA backup crew member Joe Acaba is seen at a press conference held at the Cosmonaut Hotel, Saturday, Nov. 12, 2011 at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch November 14 from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  8. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    NASA backup Flight Engineer Don Pettit speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  9. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 Soyuz Commander Sergei Volkov speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  10. Expedition 39 Press Conference

    NASA Image and Video Library

    2014-03-24

    Expedition 39 flight engineer Steve Swanson of NASA is seen in quarantine, behind glass, during the final press conference be Monday, March 24, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch March 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Bill Ingalls)

  11. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Russian backup Flight Engineer Oleg Kononenko speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  12. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 backup crew members Joseph Acaba, left, and Russian Flight Engineer Gennady Padalka share a few words during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Saturday, Nov. 12, 2011. Photo Credit: (NASA/Carla Cioffi)

  13. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 Flight Engineer Anatoly Ivanishin is seen at a press conference held at the Cosmonaut Hotel, Saturday, Nov. 12, 2011 at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch November 14 from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  14. Expedition 40 Press Conference

    NASA Image and Video Library

    2014-05-27

    A man taking a picture with a cell phone is seen reflected in the glass separating the quarantined crew during a press conference on Tuesday, May 27, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch May 29 from the Baikonur Cosmodrome. Photo Credit: (NASA/Joel Kowsky)

  15. Expedition 29 Press Conference

    NASA Image and Video Library

    2011-11-12

    Expedition 29 Russian Flight Engineer Anatoly Ivanishin answers a reporter’s question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Saturday, Nov. 12, 2011. The launch of the Soyuz spacecraft with Ivanishin, Soyuz Commander Anton Shkaplerov and NASA Flight Engineer Dan Burbank is scheduled for November 14. Photo Credit: (NASA/Carla Cioffi)

  16. Expedition 28 Press Conference

    NASA Image and Video Library

    2011-06-06

    Expedition 28 NASA Flight Engineer Mike Fossum, left, looks on as Soyuz Commander Sergei Volkov speaks during a press conference, Monday, June 6, 2011, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission is set to launch on Tuesday, June 8, from the Baikonur Cosmodrome. Photo Credit: (NASA/Carla Cioffi)

  17. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    NASA Expedition 41 backup crew member Flight Engineer Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) answers a question during a press conference Wednesday, Sept. 24, 2014 at the Cosmonaut Hotel in Baikonur, Kazakhstan. The prime crew is set to launch Sept. 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  18. Meet the Press

    ERIC Educational Resources Information Center

    Quick, Brian L.

    2004-01-01

    Objective: To field questions from a room of students simulating a press conference. Type of speech: Impromptu. Point value: 10 participation points. To receive all 10 points, students must (1) address three questions from the lectern and ask three questions from their seat (3 points), (2) respond thoroughly to each question by providing a…

  19. Expedition 6 Press Conference

    NASA Image and Video Library

    2003-05-05

    Expedition 6 Flight Engineer Nikolai Budarin, left, Commander Ken Bowersox and International Space Station Science Officer Don Pettit, right, pose for photos at a press conference at the Gagarin Cosmonaut Training Center in Star City, Russia, Thursday, May 6, 2003. Photo Credit: (NASA/Bill Ingalls)

  20. Expedition 6 Press Conference

    NASA Image and Video Library

    2003-05-05

    Expedition 6 Flight Engineer Nikolai Budarin, left, Commander Ken Bowersox and NASA International Space Station Science Officer Don Pettit, right, answer questions during a press conference at the Gagarin Cosmonaut Training Center in Star City, Russia, Thursday, May 6, 2003. Photo Credit: (NASA/Bill Ingalls)

  1. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    NASA Administrator Michael Griffin, left, Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, are seen during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  2. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    Scott Horowitz, NASA Associate Administrator for Exploration Systems, center, speaks as Jeff Hanley, Constellation Program Manager, right, looks on during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  3. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Andrew Chaikin, author of "A Man on the Moon" speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  4. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Buzz Aldrin, the second man to walk on the moon, speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  5. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Apollo 11 astronaut Buzz Aldrin, the second man to walk on the Moon, speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  6. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    NASA Deputy Administrator Lori Garver, speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  7. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Tiffany Montague, Technical Program Manager for NASA and Google Lunar X PRIZE, Google, Inc., speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  8. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Brian McLendon, VP of Engineering, Google, Inc., speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  9. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Yoshinori Yoshimura, a respresentative from the Japan Aerospace Exploration Agency (JAXA), speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  10. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Michael Weiss-Malik, Product Manager for Moon in Google Earth, Google, Inc., speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  11. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Miles O'Brien, former chief science and tech correspondent for CNN, speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  12. Meet the Press

    ERIC Educational Resources Information Center

    Quick, Brian L.

    2004-01-01

    Objective: To field questions from a room of students simulating a press conference. Type of speech: Impromptu. Point value: 10 participation points. To receive all 10 points, students must (1) address three questions from the lectern and ask three questions from their seat (3 points), (2) respond thoroughly to each question by providing a…

  13. Expedition 52 Press Conference

    NASA Image and Video Library

    2017-07-10

    Expedition 52 flight engineers Paolo Nespoli of ESA, left, Sergey Ryazanskiy of Roscosmos, center, and Expedition 52 flight engineer Randy Bresnik of NASA pose for group photograph at the conclusion of their crew press conference at the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  14. Expedition 50 Press Conference

    NASA Image and Video Library

    2016-10-26

    Expedition 50 NASA astronaut Peggy Whitson, left, Russian cosmonaut Oleg Novitskiy of Roscosmos, center, and ESA astronaut Thomas Pesquet pose for a group photograph at the conclusion of a press conference, Wednesday, Oct. 26, 2016, at the Gagarin Cosmonaut Training Center (GCTC) in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  15. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    A model of the MAVEN spacecraft is pictured during a press conference for the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  16. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    Jim Green, director, Planetary Science Division, NASA Headquarters, discusses the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  17. Expedition 52 Press Conference

    NASA Image and Video Library

    2017-07-10

    A painting of Yuri Gagarin is seen in the lobby of the building where the Expedition 52 prime and backup crews held a crew press conference on the grounds of the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  18. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    Jeff Hanley, Constellation Program Manager, speaks during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  19. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    Scott Horowitz, NASA Associate Administrator for Exploration Systems, left, looks on as Jeff Hanley, Constellation Program Manager, speaks during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  20. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    NASA Administrator Michael Griffin, left, looks on as Scott Horowitz, NASA Associate Administrator for Exploration Systems speaks during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  1. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    Members of the media listen during a press conference with NASA Administrator Michael Griffin, Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  2. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    NASA Administrator Michael Griffin, speaks during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  3. Constellation Program Press Conference

    NASA Image and Video Library

    2006-06-04

    Scott Horowitz, NASA Associate Administrator for Exploration Systems, left, and Jeff Hanley, Constellation Program Manager, are seen during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

  4. Optically Aligned Drill Press

    NASA Technical Reports Server (NTRS)

    Adderholdt, Bruce M.

    1994-01-01

    Precise drill press equipped with rotary-indexing microscope. Microscope and drill exchange places when turret rotated. Microscope axis first aligned over future hole, then rotated out of way so drill axis assumes its precise position. New procedure takes less time to locate drilling positions and produces more accurate results. Apparatus adapted to such other machine tools as milling and measuring machines.

  5. Optically Aligned Drill Press

    NASA Technical Reports Server (NTRS)

    Adderholdt, Bruce M.

    1994-01-01

    Precise drill press equipped with rotary-indexing microscope. Microscope and drill exchange places when turret rotated. Microscope axis first aligned over future hole, then rotated out of way so drill axis assumes its precise position. New procedure takes less time to locate drilling positions and produces more accurate results. Apparatus adapted to such other machine tools as milling and measuring machines.

  6. America's Enduring Ethnic Press.

    ERIC Educational Resources Information Center

    Marzolf, Marion

    Studies of the history of newspapers in the United States have virtually ignored the ethnically oriented, foreign language press. This gap in journalistic investigation should be filled by considering the two conflicting roles which ethnic newspapers fill: assimilation of the ethnic group into the mainstream of American culture and maintenance and…

  7. Drill Press Work Sample.

    ERIC Educational Resources Information Center

    Shawsheen Valley Regional Vocational-Technical High School, Billerica, MA.

    This manual contains a work sample intended to assess a handicapped student's interest in and to screen interested students into a training program in basic machine shop I. (The course is based on the entry level of the drill press operator.) Section 1 describes the assessment, correlates the work performed and worker traits required for…

  8. Google Moon Press Conference

    NASA Image and Video Library

    2009-07-19

    Alan Eustace, Senior VP of Engineering and Research, Google, Inc., speaks during a press conference, Monday, July 20, 2009, announcing the launch of Moon in Google Earth, an immersive 3D atlas of the Moon, accessible within Google Earth 5.0, Monday, July 20, 2009, at the Newseum in Washington. Photo Credit: (NASA/Bill Ingalls)

  9. Requirements for extracting mantle viscosity from glacial isostatic adjustment

    NASA Astrophysics Data System (ADS)

    Cathles, L. M.

    2012-04-01

    Extracting mantle viscosity from glacial isostatic adjustment (GIA) data is challenging because it requires a correctly posed rheological model, an accurate description of the ice and water load redistributions that occurred over at least the last glacial cycle, and the ability to interact model predictions with a large amount of observational data. To address sealevel changes, models must be based on an appropriate rheology. Daly focused attention on this critical issue 78 years ago with his down-punching hypothesis. Observing the sympathetic uplift behavior of areas peripheral to continental glacial loads, he suggested a thick lithosphere was required to force this behavior on asthenosphere flow. At the same time Haskell pointed out that deep flow in a constant viscosity Newtonian mantle would produce the observed peripheral bulge behavior without a thick lithosphere. This debate is important today because sealevel changes are particularly impacted by deep mantle viscosity and mantle rheology. Lithosphere and asthenosphere properties are another much discussed topic. The commonly observed substantial short wavelength response requires both a thin (~40 km thick) lithosphere and an asthenosphere ~25 times more fluid than the mantle. Because the manner of local ice removal can affect rebound calculations greatly, it is critical to have accurate ice and water load redistributions. Load redistributions must include changes in the levels of large lakes. Recent studies indicate how important it is to take into account sediment redistribution over the last glacial cycle. Finally, evaluation of the calculated emergence requires the comparison to large amounts of accurate (or at least critically vetted) sea level, emergence, GPS, and other kinds of data. These issues will be discussed and illustrated with some recent calculations.

  10. Ongoing glacial isostatic contributions to observations of sea level change

    NASA Astrophysics Data System (ADS)

    Tamisiea, Mark E.

    2011-09-01

    Studies determining the contribution of water fluxes to sea level rise typically remove the ongoing effects of glacial isostatic adjustment (GIA). Unfortunately, use of inconsistent terminology between various disciplines has caused confusion as to how contributions from GIA should be removed from altimetry and GRACE measurements. In this paper, we review the physics of the GIA corrections applicable to these measurements and discuss the differing nomenclature between the GIA literature and other studies of sea level change. We then examine a range of estimates for the GIA contribution derived by varying the Earth and ice models employed in the prediction. We find, similar to early studies, that GIA produces a small (compared to the observed value) but systematic contribution to the altimetry estimates, with a maximum range of -0.15 to -0.5 mm yr-1. Moreover, we also find that the GIA contribution to the mass change measured by GRACE over the ocean is significant. In this regard, we demonstrate that confusion in nomenclature between the terms 'absolute sea level' and 'geoid' has led to an overestimation of this contribution in some previous studies. A component of this overestimation is the incorrect inclusion of the direct effect of the contemporaneous perturbations of the rotation vector, which leads to a factor of ˜two larger value of the degree two, order one spherical harmonic component of the model results. Aside from this confusion, uncertainties in Earth model structure and ice sheet history yield a spread of up to 1.4 mm yr-1 in the estimates of this contribution. However, even if the ice and Earth models were perfectly known, the processing techniques used in GRACE data analysis can introduce variations of up to 0.4 mm yr-1. Thus, we conclude that a single-valued 'GIA correction' is not appropriate for sea level studies based on gravity data; each study must estimate a bound on the GIA correction consistent with the adopted data-analysis scheme.

  11. A benchmark study for glacial isostatic adjustment codes

    NASA Astrophysics Data System (ADS)

    Spada, G.; Barletta, V. R.; Klemann, V.; Riva, R. E. M.; Martinec, Z.; Gasperini, P.; Lund, B.; Wolf, D.; Vermeersen, L. L. A.; King, M. A.

    2011-04-01

    The study of glacial isostatic adjustment (GIA) is gaining an increasingly important role within the geophysical community. Understanding the response of the Earth to loading is crucial in various contexts, ranging from the interpretation of modern satellite geodetic measurements (e.g. GRACE and GOCE) to the projections of future sea level trends in response to climate change. Modern modelling approaches to GIA are based on various techniques that range from purely analytical formulations to fully numerical methods. Despite various teams independently investigating GIA, we do not have a suitably large set of agreed numerical results through which the methods may be validated; a community benchmark data set would clearly be valuable. Following the example of the mantle convection community, here we present, for the first time, the results of a benchmark study of codes designed to model GIA. This has taken place within a collaboration facilitated through European Cooperation in Science and Technology (COST) Action ES0701. The approaches benchmarked are based on significantly different codes and different techniques. The test computations are based on models with spherical symmetry and Maxwell rheology and include inputs from different methods and solution techniques: viscoelastic normal modes, spectral-finite elements and finite elements. The tests involve the loading and tidal Love numbers and their relaxation spectra, the deformation and gravity variations driven by surface loads characterized by simple geometry and time history and the rotational fluctuations in response to glacial unloading. In spite of the significant differences in the numerical methods employed, the test computations show a satisfactory agreement between the results provided by the participants.

  12. Bouguer gravity anomaly and isostatic residual gravity maps of the Tonopah 1 degree by 2 degrees Quadrangle, central Nevada

    USGS Publications Warehouse

    Plouff, Donald

    1992-01-01

    A residual isostatic gravity map (sheet 2) was prepared so that the regional effect of isostatic compensation present on the Bouguer gravity anomaly map (sheet 1) would be minimized. Isostatic corrections based on the Airy-Heiskanen system (Heiskanen and Vening Meinesz, 1958, p. 135-137) were estimated by using 3-minute topographic digitization and applying the method of Jachens and Roberts (1981). Parameters selected for the isostatic model were 25 km for the normal crustal thickness at sea level, 2.67 g/cm3 for the density of the crust, and 0.4 g/cm3 for the contrast in density between the crust and the upper mantle. These parameters were selected so that the isostatic residual gravity map would be consistent with isostatic residual gravity maps of the adjacent Walker Lake quadrangle (Plouff, 1987) and the state of Nevada (Saltus, 1988c).

  13. The alignment and isostatic mount bonding technique of the aerospace Cassegrain telescope primary mirror

    NASA Astrophysics Data System (ADS)

    Lin, Wei Cheng; Chang, Shenq-Tsong; Lin, Yu-Chuan; Hsu, Ming-Ying; Chang, Yu-Ting; Chang, Sheng-Hsiung; Huang, Ting-Ming

    2012-10-01

    In order to meet both optical performance and structural stiffness requirements of the aerospace Cassegrain telescope, iso-static mount is used as the interface between the primary mirror and the main plate. This article describes the alignment and iso-static mount bonding technique of the primary mirror by assistance of CMM. The design and assembly of mechanical ground support equipment (MGSE) which reduces the deformation of primary mirror by the gravity effect is also presented. The primary mirror adjusting MGSE consists of X-Y linear translation stages, rotation stage and kinematic constrain platform which provides the function of decenter, orientation, tilt and height adjustment of the posture sequentially. After CMM measurement, the radius of curvature, conic constant, decenter and tilt, etc. will be calculated. According to these results, the posture of the mirror will be adjusted to reduce the tilt by the designed MGSE within 0.02 degrees and the distance deviation from the best fitted profile of mirror to main plate shall be less than 0.01 mm. After that, EC 2216 adhesive is used to bond mirror and iso-static mount. During iso-static mount bonding process, CMM is selected to monitor the relative position deviation of the iso-static mount until the adhesive completely cured. After that, the wave front sensors and strain gauges are used to monitor the strain variation while the iso-static mount mounted in the main plate with the screws by the torque wrench. This step is to prevent deformation of the mirror caused from force of the iso-static mount during the mounting process. In the end, the interferometer is used for the optical performance test with +1G and -1G to check the alignment and bonding technique is well or not.

  14. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    Craig DeForest, a staff scientist at the Southwest Research Institute in Boulder, Colo., speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington. The briefing was held to discusses new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth)

  15. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    Madhulika Guhathakurta, seated left, STEREO program scientist, speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington as Craig DeForest, David Webb and Alysha Reinard, look on. The briefing was held to discusses new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth)

  16. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    Craig DeForest, second from left, speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington as Madhulika Guhathakurta, left, David Webb and Alysha Reinard look on. The briefing was held to discusses new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth)

  17. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    Madhulika Guhathakurta, seated left, STEREO program scientist, speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington as Craig DeForest, David Webb and Alysha Reinard, look on. The briefing was held to discusses new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth).

  18. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    David Webb, a research physicist from the Institute for Scientific Research at Boston College speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington. The briefing was held to discuss new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth)

  19. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    Expedition 41 Soyuz Commander Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos) and Flight Engineer Elena Serova of Roscosmos hold up tiger toys that will be carried with them to the International Space Station to commemorate International Tiger Day at a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Wednesday, Sept. 24, 2014. The mission is set to launch Sept. 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  20. Expedition 32 Press Conference

    NASA Image and Video Library

    2012-07-13

    Quarantined Expedition 32 JAXA (Japan Aerospace Exploration Agency) Flight Engineer Akihiko Hoshide answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Friday, July 13, 2012 in Baikonur, Kazakhstan. The launch of the Soyuz spacecraft with Hoshide, Soyuz Commander Yuri Malenchenko, and NASA Flight Engineer Sunita Williams is scheduled for 8:40 a.m. local time on Sunday, July 15. Photo Credit (NASA/Carla Cioffi)

  1. Expedition 34 Press Conference

    NASA Image and Video Library

    2012-12-18

    Expedition 34/35 NASA Flight Engineer Tom Marshburn answers a reporter's question at a press conference held at the Cosmonaut Hotel, on Tuesday, Dec. 18, 2012, in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for December 19 and will send Marshburn, Roman Romanenko of ROSCOSMOS and Chris Hadfield of the Canadian Space Agency on a five-month mission aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

  2. Expedition 32 Press Conference

    NASA Image and Video Library

    2012-07-13

    Quarantined Expedition 32 JAXA (Japan Aerospace Exploration Agency) Flight Engineer Akihiko Hoshide, left, answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Friday, July 13, 2012 in Baikonur, Kazakhstan. Seated next to him is Soyuz Commander Yuri Malenchenko. The launch of the Soyuz spacecraft with Hoshide, Malenchenko, and NASA Flight Engineer Sunita Williams is scheduled for 8:40 a.m. local time on Sunday, July 15. Photo Credit (NASA/Carla Cioffi)

  3. Expedition 34 Press Conference

    NASA Image and Video Library

    2012-12-18

    Expedition 34/35 Flight Engineer and Expedition 35 Commander Chris Hadfield of the Canadian Space Agency (CSA) answers a reporter's question at a press conference held at the Cosmonaut Hotel, on Tuesday, Dec. 18, 2012, in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for December 19 and will send Hadfield, Tom Marshburn of NASA and Roman Romanenko of ROSCOSMOS on a five-month mission aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

  4. Expedition 33 Press Conference

    NASA Image and Video Library

    2012-10-22

    Expedition 33 Soyuz Commander Oleg Novitskiy answers a reporters question during a press conference held at the Cosmonaut Hotel, on Monday, October 22, 2012, in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for October 23 and will send Expedition 33/34 Flight Engineer Kevin Ford of NASA, Soyuz Commander Oleg Novitskiy and Flight Engineer Evgeny Tarelkin of ROSCOSMOS on a five-month mission aboard the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  5. Expedition 32 Press Conference

    NASA Image and Video Library

    2012-07-13

    Quarantined Expedition 32 Soyuz Commander Yuri Malenchenko, right, answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Friday, July 13, 2012 in Baikonur, Kazakhstan. Seated next to him is JAXA Flight Engineer Akihiko Hoshide. The launch of the Soyuz spacecraft with Malenchenko, NASA Flight Engineer Sunita Williams and Hoshide is scheduled for 8:40 a.m. local time on Sunday, July 15. Photo Credit (NASA/Carla Cioffi)

  6. Expedition 37 Press Conference

    NASA Image and Video Library

    2013-09-24

    Expedition 37 NASA Flight Engineer Michael Hopkins answers a reporter's question at a press conference held at the Cosmonaut Hotel, on Tuesday, Sept. 24, 2013, in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for September 26 and will send Hopkins, Soyuz Commander Oleg Kotov and Russian Flight Engineer Sergei Ryazansky on a five and a half-month mission aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

  7. Expedition 37 Press Conference

    NASA Image and Video Library

    2013-09-24

    Expedition 37 backup crewmember Alexander Skvortsov anwers a reporter’s question at a press conference held at the Cosmonaut Hotel, on Tuesday, Sept. 24, 2013, in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for September 26 and will send Kotov, Hopkins and Ryazansky on a five and a half-month mission aboard the International Space Station. Photo Credit: (NASA/Carla Cioffi)

  8. Astrobiology Press Conference

    NASA Image and Video Library

    2010-12-02

    Steven Benner, a distinguished fellow at the Foundation for Applied Molecular Evolution, speaks during a press conference, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)

  9. Astrobiology Press Conference

    NASA Image and Video Library

    2010-12-02

    Felisa Wolfe-Simon, a lead researcher and NASA astrobiology research fellow, speaks during a press conference, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)

  10. Astrobiology Press Conference

    NASA Image and Video Library

    2010-12-02

    Felisa Wolfe-Simon, director, Astrobiology Program, NASA Headquarters, speaks during a press conference, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)

  11. Astrobiology Press Conference

    NASA Image and Video Library

    2010-12-02

    Pamela Conrad, an astrobiologist from Goddard Space Flight Center, speaks during a press conference, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)

  12. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 backup crew member Reid Wiseman of NASA is seen in quarantine, behind glass, during the final press conference held a day ahead of the launch of Expedition 38 prime crew members; Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, Soyuz Commander Mikhail Tyurin of Roscosmos, and, Flight Engineer Rick Mastracchio of NASA, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  13. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    NASA Expedition 41 backup crew member Flight Engineer Scott Kelly of NASA answers a question during a press conference Wednesday, Sept. 24, 2014 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Expedition 41 Flight Engineer Barry Wilmore of NASA, Soyuz Commander Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos), and Flight Engineer Elena Serova of Roscosmos are set to launch Sept. 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  14. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 Soyuz Commander Mikhail Tyurin of Roscosmos, right, talks as Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, listens, from quarantine behind glass, during the final press conference held a day ahead of their launch with fellow crew mate, Flight Engineer Rick Mastracchio of NASA, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  15. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency is seen in quarantine, behind glass, during the final press conference held a day ahead of his launch with fellow crew mates, Expedition 38 Soyuz Commander Mikhail Tyurin of Roscosmos, and, Flight Engineer Rick Mastracchio of NASA, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  16. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    Expedition 41 Flight Engineer Barry Wilmore of NASA answers a question during a press conference on Wednesday, Sept. 24, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for Sept. 26 and will carry Wilmore, Elena Serova of the Russian Federal Space Agency (Roscosmos), and Alexander Samokutyaev of Roscosmos into orbit to begin their five and a half month mission on the International Space Station. Photo Credit: (NASA/Aubrey Gemignani)

  17. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 Soyuz Commander Mikhail Tyurin of Roscosmos is seen in quarantine behind glass during the final press conference held a day ahead of his launch with fellow crew mates, Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, and, Flight Engineer Rick Mastracchio of NASA, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  18. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 backup crew member Alexander Gerst of the European Space Agency is seen in quarantine, behind glass, during the final press conference held a day ahead of the launch of Expedition 38 prime crew members; Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, Soyuz Commander Mikhail Tyurin of Roscosmos, and, Flight Engineer Rick Mastracchio of NASA, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  19. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    William Bo-Ricki, Kepler principal investigator at NASA's Ames Research Center, speaks during a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  20. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    Jon Morse, NASA's Astrophysics Division Director, left, speaks during a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March asWilliam Bo-Ricki, Kepler principal investigator at NASA's Ames Research Center, looks on. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  1. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    Sara Seager, Professor of Planetary Science at the Massachusetts Institute of Technology, speaks during a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  2. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    Bruce Jakosky, MAVEN principal investigator, University of Colorado Boulder Laboratory for Atmospheric and Space Physics, discusses the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  3. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    Madhulika Guhathakurta, seated left, STEREO program scientist, speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington. The briefing was held to discusses new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth)

  4. STEREO Press Briefing

    NASA Image and Video Library

    2011-08-17

    Alysha Reinard, as research scientist with National Oceanic and Atmospheric Administration and the University of Colorado Boulder, speaks during a press briefing, Thursday, Aug. 18, 2011, at NASA Headquarters in Washington. The briefing was held to discusses new details about the structure of solar storms and the impact they have on Earth. The new information comes from NASA's Solar Terrestrial Relations Observatory, or STEREO, spacecraft and other NASA probes. Photo Credit: (NASA/GSFC/Rebecca Roth)

  5. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    Expedition 41 prime crew members, Flight Engineer Barry Wilmore of NASA, left, Soyuz Commander Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos), center, and Flight Engineer Elena Serova of Roscosmos, right, pose for a photo at the conclusion of the press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Wednesday, Sept. 24, 2014. Their mission to the International Space Station is set to launch Sept. 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  6. Expedition 52 Press Conference

    NASA Image and Video Library

    2017-07-10

    Expedition 52 prime and backup crews: Paolo Nespoli of ESA, left, Randy Bresnik of NASA, Sergey Ryazanskiy of Roscosmos, Alexander Misurkin of Roscosmos, Norishige Kanai of the Japan Aerospace Exploration Agency (JAXA) and, Mark Vande Hei of NASA pose for group photograph at the conclusion of their crew press conference at the Gagarin Cosmonaut Training Center (GCTC), Monday, July 10, 2017 in Star City, Russia. Photo Credit: (NASA/Bill Ingalls)

  7. Expedition 40 Press Conference

    NASA Image and Video Library

    2014-05-27

    Expedition 40 Flight Engineer Alexander Gerst of the European Space Agency, ESA, left, Soyuz Commander Maxim Suraev of the Russian Federal Space Agency, Roscosmos, center, and Flight Engineer Reid Wiseman of NASA, right, wave to those gathered at the conclusion of a press conference, Tuesday, May 27, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch May 29 from the Baikonur Cosmodrome. Photo Credit: (NASA/Joel Kowsky)

  8. Expedition 42 Press Conference

    NASA Image and Video Library

    2014-11-22

    Expedition 42 Flight Engineer Terry Virts of NASA (left), Soyuz Commander Anton Shkaplerov of the Russian Federal Space Agency (Roscosmos) (center), and Flight Engineer Samantha Cristoforetti of the European Space Agency (right), pose for a photo at the conclusion of the press conference, Saturday, Nov. 22, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch Nov. 24 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  9. Expedition 40 Press Conference

    NASA Image and Video Library

    2014-05-27

    Expedition 40 Flight Engineer Alexander Gerst of the European Space Agency, ESA, left, Soyuz Commander Maxim Suraev of the Russian Federal Space Agency, Roscosmos, center, and Flight Engineer Reid Wiseman of NASA, right, pose for a picture at the conclusion of a press conference, Tuesday, May 27, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch May 29 from the Baikonur Cosmodrome. Photo Credit: (NASA/Joel Kowsky)

  10. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    Expedition 41 Flight Engineer Barry Wilmore of NASA, left, Soyuz Commander Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos), center, and Flight Engineer Elena Serova of Roscosmos, right, wave to the crowd at the conclusion of the press conference, Wednesday, Sept. 24, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch Sept. 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  11. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    John Grunsfeld, associate administrator for the Science Mission Directorate, NASA Headquarters, Washington, introduces a panel to discuss the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  12. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    John Grunsfeld, associate administrator for the Science Mission Directorate, NASA Headquarters, Washington, discusses the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  13. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    David Mitchell, MAVEN project manager, NASA's Goddard Space Flight Center, discusses the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  14. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    Alan Boss, an astrophyscist at the Carnegie Institution at the Department of Terrestrial Magnetism speaks during a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  15. Importance of far-field topographic and isostatic corrections for regional density modelling

    NASA Astrophysics Data System (ADS)

    Szwillus, Wolfgang; Ebbing, Jörg; Holzrichter, Nils

    2016-10-01

    The long-wavelength gravity field contains information about processes in the sublithospheric mantle. As satellite-derived gravity models now provide the long to medium-wavelength gravity field at unprecedented accuracy, techniques used to process gravity data need to be updated. We show that when determining these long-wavelengths, the treatment of topographic-isostatic effect (TIE) and isostatic effects (IE) is a likely source of error. We constructed a global isostatic model and calculated global TIE and IE. These calculations were done for ground stations as well as stations at satellite height. We considered both gravity and gravity gradients. Using these results, we determined how much of the gravity signal comes from distant sources. We find that a significant long-wavelength bias is introduced if far-field effects on the topographic effect are neglected. However, due to isostatic compensation far-field effects of the topographic effect are to a large degree compensated by the far-field IE. This means that far-field effects can be reduced effectively by always considering topographic masses together with their compensating isostatic masses. We show that to correctly represent the ultra-long wavelengths, a global background model should be used. This is demonstrated both globally and for a continental-scale case area in North America. In the case of regional modelling, where the ultra-long wavelengths are not of prime importance, gravity gradients can be used to help minimize correction errors caused by far-field effects.

  16. 37. PRESSING TILES FROM PLASTER MOLDS, USING A HAND PRESS ...

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

    37. PRESSING TILES FROM PLASTER MOLDS, USING A HAND PRESS CONSTRUCTED IN 1986. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  17. Cold Isostatic-Pressured Silver Nanowire Electrodes for Flexible Organic Solar Cells via Room-Temperature Processes.

    PubMed

    Seo, Ji Hoon; Hwang, Inchan; Um, Han-Don; Lee, Sojeong; Lee, Kangmin; Park, Jeonghwan; Shin, Hyeonoh; Kwon, Tae-Hyuk; Kang, Seok Ju; Seo, Kwanyong

    2017-08-01

    Transparent conducting electrodes (TCEs) are considered to be an essential structural component of flexible organic solar cells (FOSCs). Silver nanowire (AgNW) electrodes are widely used as TCEs owing to their excellent electrical and optical properties. The fabrication of AgNW electrodes has faced challenges in terms of forming large uniform interconnected networks so that high conductivity and reproducibility can be achieved. In this study, a simple method for creating an intimate contact between AgNWs that uses cold isostatic pressing (CIP) is demonstrated. This method increases the conductivity of the AgNW electrodes, which enables the fabrication of high-efficiency inverted FOSCs that have a power conversion efficiency of 8.75% on flexible polyethylene terephthalate with no short circuiting occurring as the CIP process minimizes the surface roughness of the AgNW electrode. This allows to achieve 100% manufacturing yield of FOSCs. Furthermore, these highly efficient FOSCs are proven to only be 2.4% less efficient even for an extreme bending radius of R ≈ 1.5 mm, compared with initial efficiency. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. TiC/Ti-Al composite fabricated by SHS/dynamic pseudo isostatic compaction through sand medium

    SciTech Connect

    Ohyanagi, M.; Fukushima, M.; Koizumi, M.

    1996-12-31

    TiC/Ti-Al composite was fabricated by pseudo isostatic compaction (DPIC) just after self-propagating high temperature synthesis (SHS). The pressing of 100 MPa was performed through a sand medium. The process enables to simultaneously synthesize and densify the TiC/Ti-Al composite from Ti/C/Al powders. The sample could be taken out from a reaction vessel within a couple of minutes after ignition. The adiabatic combustion temperatures were also calculated as a function of the mixing ratio of the elemental powders in the reaction system. X-ray diffraction patterns of TiC/Ti-Al produced revealed that the Ti-Al portion consisted of TiAl, Ti{sub 3}Al, TiAl{sub 3} and a slight Ti{sub 4}Al{sub 2}C{sub 2} alloys. The time delay between SHS and DPIC was affected greatly on the product density. The influence of the reactant mixing time on the phase component of the product was also studied. The density and Vickers hardness of the composite were highest in a mixing mole ratio of Ti/C/Al = 2/1/1, 4.2 g/cm{sup 3} and 13 GPa. The Young`s modulus and bending strength were approximately 300 GPa and 500 MPa, respectively.

  19. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    Expedition 18 Commander Michael Fincke answers reporters' questions during a press conference held at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. Fincke will launch on the Soyuz TMA-13 spacecraft along with Expedition 18 Flight Engineer Yuri V. Lonchakov and American spaceflight participant Richard Garriott on Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  20. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    American spaceflight participant Richard Garriott, left, and Expedition 18 Commander Michael Fincke answer reporters' questions during a press conference held at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. Garriott and Fincke will launch on the Soyuz TMA-13 spacecraft along with Expedition 18 Flight Engineer Yuri V. Lonchakov on Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  1. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    Expedition 18 Flight Engineer Yuri V. Lonchakov, right, Expedition 18 Commander Michael Fincke and American spaceflight participant Richard Garriott, left, pose for photographs after a press conference held at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. The Expedition 18 crew will launch on the Soyuz TMA-13 spacecraft on Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  2. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    The quarantined crew, from left, American spaceflight participant Richard Garriott, Expedition 18 Commander Michael Fincke, Flight Engineer Yuri V. Lonchakov, back up Expedition 18 Commander Gennady Padalka, Flight Engineer Mike Barratt and spaceflight participant Nik Halik answer reporters questions during a press conference at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. Fincke, Lonchakov and Garriott are scheduled to launch Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  3. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    Expedition 18 Commander Michael Fincke, left, and Flight Engineer Yuri V. Lonchakov answer reporters' questions during a press conference held at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. Fincke and Lonchakov will launch on the Soyuz TMA-13 spacecraft along with American spaceflight participant Richard Garriott on Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  4. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    American spaceflight participant Richard Garriott answers reporters' questions during a press conference held at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. Garriott will launch on the Soyuz TMA-13 spacecraft along with Expedition 18 Commander Michael Fincke and Flight Engineer Yuri V. Lonchakov on Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  5. Expedition 18 Press Conference

    NASA Image and Video Library

    2008-10-10

    Expedition 18 Flight Engineer Yuri V. Lonchakov answers reporters' questions during a press conference held at the Cosmonaut Hotel, Saturday, Oct. 11, 2008, in Baikonur, Kazakhstan. Lonchakov will launch on the Soyuz TMA-13 spacecraft along with Expedition 18 Commander Michael Fincke and American spaceflight participant Richard Garriott on Oct. 12 and dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  6. Expedition 43 Press Conference

    NASA Image and Video Library

    2015-03-26

    Expedition 43 Russian cosmonaut Gennady Padalka of the Russian Federal Space Agency (Roscosmos) listens to a reporter’s question as he and, Russian cosmonaut Mikhail Kornienko of Roscosmos, and NASA Astronaut Scott Kelly participate in a crew press conference, Thursday, March 26, 2015, at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, Kornienko, and Padalka launched to the International Space Station in the Soyuz TMA-16M spacecraft from the Baikonur Cosmodrome in Kazakhstan March 28, Kazakh time (March 27 Eastern time.) As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

  7. Expedition 43 Press Conference

    NASA Image and Video Library

    2015-03-26

    Expedition 43 Russian cosmonaut Mikhail Kornienko of the Russian Federal Space Agency (Roscosmos) answers reporter’s questions as he and, Russian cosmonaut Gennady Padalka of Roscosmos, and NASA Astronaut Scott Kelly participate in a crew press conference, Thursday, March 26, 2015, at the Cosmonaut Hotel in Baikonur, Kazakhstan. Kelly, Kornienko, and Padalka launched to the International Space Station in the Soyuz TMA-16M spacecraft from the Baikonur Cosmodrome in Kazakhstan March 28, Kazakh time (March 27 Eastern time.) As the one-year crew, Kelly and Kornienko will return to Earth on Soyuz TMA-18M in March 2016. Photo Credit (NASA/Bill Ingalls)

  8. Expedition 40 Press Conference

    NASA Image and Video Library

    2014-05-27

    Expedition 40 Soyuz Commander Maxim Suraev of the Russian Federal Space Agency, Roscosmos, second left, reacts as he is introduced during a press conference, Tuesday, May 27, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. Expedition 40 Soyuz Commander Maxim Suraev of the Russian Federal Space Agency, Roscosmos, Flight Engineer Alexander Gerst of the European Space Agency, ESA, and Flight Engineer Reid Wiseman of NASA will launch aboard their Soyuz TMA-13M spacecraft on their mission to the International Space Station in the early hours of May 29. Photo Credit: (NASA/Joel Kowsky)

  9. Astrobiology Press Conference

    NASA Image and Video Library

    2010-12-02

    Steven Benner, a distinguished fellow at the Foundation for Applied Molecular Evolution, right, speaks during a press conference as Mary Voytek, director of the Astrobiology Program at NASA looks on, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)

  10. Astrobiology Press Conference

    NASA Image and Video Library

    2010-12-02

    Felisa Wolfe-Simon, a lead researcher and NASA astrobiology research fellow, speaks during a press conference, as Mary Voytek, Steven Benner and Pamela Conrad look on, Thursday, Dec. 2, 2010, at NASA Headquarters in Washington. NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth. Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. Photo Credit: (NASA/Paul E. Alers)

  11. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    William Bo-Ricki, Kepler principal investigator at NASA's Ames Research Center, second from left, speaks during a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March as Jon Morse, NASA's Astrophysics Division Director, left, looks on. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  12. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    William Bo-Ricki, Kepler principal investigator at NASA's Ames Research Center, second from left, speaks during a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March. Others seated include Jon Morse, NASA's Astrophysics Director, Sara Seager, Professor of Planetary Science and Physics at MIT, and Alan Boss, an Astrophysicist at the Carnegie Institution at the Department of Terrestrial Magnetism in Washington, right. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  13. Expedition 40 Press Conference

    NASA Image and Video Library

    2014-05-27

    Expedition 40 prime crew members Flight Engineer Alexander Gerst of the European Space Agency, ESA, far left, Soyuz Commander Maxim Suraev of the Russian Federal Space Agency, Roscosmos, second left, and Flight Engineer Reid Wiseman of NASA, center, pose for a picture with Expedition 40 backup crew members Flight Engineer Terry Virts of NASA, third right, Soyuz Commander Anton Shkaplerov of Roscosmos, and Flight Engineer Samantha Cristoforetti of ESA at the conclusion a press conference, Tuesday, May 27, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch May 29 from the Baikonur Cosmodrome. Photo Credit: (NASA/Joel Kowsky)

  14. Expedition 42 Press Conference

    NASA Image and Video Library

    2014-11-22

    Family visits with Expedition 42 Soyuz Commander Anton Shkaplerov of the Russian Federal Space Agency (Roscosmos) through glass at the conclusion of the press conference, Saturday, Nov. 22, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for Nov. 24 and will carry Shkaplerov, Flight Engineer Terry Virts of NASA , and Flight Engineer Samantha Cristoforetti of the European Space Agency into orbit to begin their five and a half month mission on the International Space Station. Photo Credit: (NASA/Aubrey Gemignani)

  15. Expedition 42 Press Conference

    NASA Image and Video Library

    2014-11-22

    Flight Engineer Samantha Cristoforetti of the European Space Agency (ESA) speaks with friends and family through glass at the conclusion of the press conference, Saturday, Nov. 22, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. Launch of the Soyuz rocket is scheduled for Nov. 24 and will carry Cristoforetti, Flight Engineer Terry Virts of NASA , and Soyuz Commander Anton Shkaplerov of the Russian Federal Space Agency (Roscosmos) into orbit to begin their five and a half month mission on the International Space Station. Photo Credit: (NASA/Aubrey Gemignani)

  16. Expedition 41 Press Conference

    NASA Image and Video Library

    2014-09-24

    Expedition 41 prime crew members, Flight Engineer Barry Wilmore of NASA, right, Soyuz Commander Alexander Samokutyaev of the Russian Federal Space Agency (Roscosmos), center, and Flight Engineer Elena Serova of Roscosmos, left, pose for a photo with items they will take with them to the International Space Station at the conclusion of the press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Wednesday, Sept. 24, 2014. The mission is set to launch Sept. 26 from the Baikonur Cosmodrome. Photo Credit: (NASA/Aubrey Gemignani)

  17. Expedition 40 Press Conference

    NASA Image and Video Library

    2014-05-27

    A reflection of the audience can been seen in the quarantine glass as Expedition 40 Flight Engineer Alexander Gerst of the European Space Agency, ESA, left, Soyuz Commander Maxim Suraev of the Russian Federal Space Agency, Roscosmos, center, and Flight Engineer Reid Wiseman of NASA, right, pose for a group picture at the conclusion of a press conference, Tuesday, May 27, 2014, at the Cosmonaut Hotel in Baikonur, Kazakhstan. The mission to the International Space Station is set to launch May 29 from the Baikonur Cosmodrome. Photo Credit: (NASA/Joel Kowsky)

  18. Kepler Press Conference

    NASA Image and Video Library

    2009-08-05

    William Bo-Ricki, Kepler principal investigator at NASA's Ames Research Center, second from left, is joined by Jon Morse, left, Sara Seager, and Alan Boss while speaking at a press conference, Thursday, Aug. 6, 2009, at NASA Headquarters in Washington about the scientific observations coming from the Kepler spacecraft that was launched this past March. Kepler is NASA's first mission that is capable of discovering earth-sized planets in the habitable zones of stars like our Sun. Photo Credit: (NASA/Paul E. Alers)

  19. Do crustal deformations observed by GPS in Tierra del Fuego (Argentina) reflect glacial-isostatic adjustment?

    NASA Astrophysics Data System (ADS)

    Mendoza, L.; Richter, A.; Hormaechea, J. L.; Perdomo, R.; Del Cogliano, D.; Dietrich, R.; Fritsche, M.

    2010-09-01

    Vertical site velocities determined by geodetic GPS observations in the Lago Fagnano area, Tierra del Fuego main island, are interpreted with respect to their potential relation with the glacial-isostatic crustal response to ice mass changes. The spatial pattern of the uplift rates, in combination with the horizontal crustal deformation pattern, point towards a fault-tectonic rather than glacial-isostatic origin of the determined vertical crustal deformations. This implies rather small GIA effects pointing towards relatively small Holocene ice-mass changes in Tierra del Fuego. However, these findings are considered to be preliminary. They should be confirmed by additional observations covering an extended area with GPS sites.

  20. Four Theories of the Press.

    ERIC Educational Resources Information Center

    Siebert, Fred S.; And Others

    A systematic understanding of the press requires an understanding of the social and political structures within which the press operates. This book discusses four theories that have determined the kind of press the Western world has had: authoritarian, libertarian, socially responsible, and Soviet communist. Each chapter discusses press…

  1. Australia's lithospheric density field, and its isostatic equilibration

    NASA Astrophysics Data System (ADS)

    Aitken, A. R. A.; Altinay, C.; Gross, L.

    2015-12-01

    subdivisions within each. The lithospheric static pressure field was resolved in 3D from the gravity and density fields. The pressure field model also highlights the fundamental difference between the oceanic and continental domains, with the former possessing lower pressure through most of the model. Overall pressure variability is large in the upper crust (60 MPa) but reduces significantly by -30 km elevation (20-30 MPa). By -50 km elevation, thick lower-crust generates further disequilibria (25-35 MPa) that are not compensated until -125 km elevation (10-20 MPa). Beneath -125 km elevation higher pressure is observed in the continental domain, extending to the base of the model. This indicates a lithosphere that is to a large degree isostatically compensated near the base of the felsic-intermediate continental crust, and again near the theoretical base of mature oceanic lithosphere.

  2. Quantifying isostatic responses to Cenozoic incision in the Gamburtsev Subglacial Mountains and the Recovery catchment sectors of East Antarctica

    NASA Astrophysics Data System (ADS)

    Ferraccioli, F.; Paxman, G.; Jamieson, S.; Bentley, M.; Ross, N.; Watts, A. B.; Jordan, T. A.; Forsberg, R.

    2016-12-01

    The relative roles of climate and tectonics in mountain building have been widely debated. Central to this debate is the process of flexural uplift in response to valley incision. Here we quantify erosion-driven peak uplift in two sectors of East Antarctica that differ in terms of their subglacial landscape and geological and glaciological settings: the Gamburtsev Subglacial Mountains and the Recovery catchment. The inherited pre-glacial fluvial landscape of the Gamburtsevs in interior East Antarctica has been overprinted by Alpine-style glacial erosion. In contrast, the bedrock topography beneath the Recovery catchment is bimodal with the highlands of the Shackleton Range and Theron Mountains separated by deep fault-controlled subglacial troughs, presently occupied by fast-flowing ice streams. In both these regions inferred Mesozoic rifting and strike-slip motion may have provided tectonic triggers for initial mountain range uplift (Ferraccioli et al., 2011 Nature). However, the isostatic response to more recent Cenozoic valley incision remains to be quantified. Inverse spectral and forward modelling methods indicate that the effective elastic thickness of the lithosphere is surprisingly low, considering the cratonic setting of East Antarctica (5-20 km in the Gamburtsev region and 15-25 km in Recovery). 3D flexural models indicate that valley incision has contributed only 17-25% of Gamburtsev peak uplift (Paxman et al., 2016 EPSL in press). These values are typical of temperate mountain ranges, suggesting that most of the valley incision in the Gamburtsevs occurred prior to widespread East Antarctic Ice Sheet development at the Eocene-Oligocene climate transition (ca. 34 Ma ago). In the Recovery catchment, flexure instead accounts for up to 44-56% of peak uplift, which is similar to estimates previously reported in the Transantarctic Mountains (Stern et al., 2005, Geology). Peak uplift was triggered here by selective Oligocene-Neogene age linear erosion in the

  3. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    L-R: Dwayne Brown, NASA Public Affairs Officer, Jim Green, director, Planetary Science Division, NASA Headquarters, Lisa May, MAVEN program executive, NASA Headquarters, Kelly Fast, MAVEN program scientist, NASA Headquarters, Bruce Jakosky, MAVEN principal investigator, University of Colorado Boulder Laboratory for Atmospheric and Space Physics, and David Mitchell, MAVEN project manager, NASA's Goddard Space Flight Center, Greenbelt, Md. discuss the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  4. MAVEN Press Briefing

    NASA Image and Video Library

    2013-10-28

    L-R: Jim Green, director, Planetary Science Division, NASA Headquarters, Lisa May, MAVEN program executive, NASA Headquarters, Kelly Fast, MAVEN program scientist, NASA Headquarters, Bruce Jakosky, MAVEN principal investigator, University of Colorado Boulder Laboratory for Atmospheric and Space Physics, and David Mitchell, MAVEN project manager, NASA's Goddard Space Flight Center, Greenbelt, Md. are applauded at the end of a panel discussion on the upcoming launch of the Mars Atmosphere and Volatile Evolution (MAVEN) mission, at a press conference at NASA Headquarters in Washington on Monday, Oct. 28th, 2013. MAVEN is the agency's next mission to Mars and the first devoted to understanding the upper atmosphere of the Red Planet. (Photo credit: NASA/Jay Westcott)

  5. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency is seen in quarantine, behind glass, during the final press conference held a day ahead of his launch with fellow crew mates, Expedition 38 Soyuz Commander Mikhail Tyurin of Roscosmos, and, Flight Engineer Rick Mastracchio of NASA, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. An Olympic torch that will be launched with the crew for a four-day visit to the station is seen on the left. The torch will return to Earth with another trio of station residents on Nov. 11 and will be part of the torch relay that ends with the lighting of the flame at the Fisht Stadium in Sochi, Russia Feb. 7 to mark the opening of the 2014 Winter Olympics. Photo Credit: (NASA/Bill Ingalls)

  6. Expedition 38 Press Conference

    NASA Image and Video Library

    2013-11-06

    Expedition 38 Flight Engineer Rick Mastracchio of NASA talks, while in quarantine behind glass, during the final press conference held a day ahead of his launch with fellow crew mates, Soyuz Commander Mikhail Tyurin of Roscosmos, and, Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, to the International Space Station, Wednesday, Nov. 6, 2013 at the Cosmonaut Hotel in Baikonur, Kazakhstan. An Olympic torch that will be launched with the crew for a four-day visit to the station is seen next to Mastracchio. The torch will return to Earth with another trio of station residents on Nov. 11 and will be part of the torch relay that ends with the lighting of the flame at the Fisht Stadium in Sochi, Russia Feb. 7 to mark the opening of the 2014 Winter Olympics. Photo Credit: (NASA/Bill Ingalls)

  7. TOPICAL REVIEW: Jamming of soft particles: geometry, mechanics, scaling and isostaticity

    NASA Astrophysics Data System (ADS)

    van Hecke, M.

    2010-01-01

    Amorphous materials as diverse as foams, emulsions, colloidal suspensions and granular media can jam into a rigid, disordered state where they withstand finite shear stresses before yielding. Here we review the current understanding of the transition to jamming and the nature of the jammed state for disordered packings of particles that act through repulsive contact interactions and are at zero temperature and zero shear stress. We first discuss the breakdown of affine assumptions that underlies the rich mechanics near jamming. We then extensively discuss jamming of frictionless soft spheres. At the jamming point, these systems are marginally stable (isostatic) in the sense of constraint counting, and many geometric and mechanical properties scale with distance to this jamming point. Finally, we discuss current explorations of jamming of frictional and non-spherical (ellipsoidal) particles. Both friction and asphericity tune the contact number at jamming away from the isostatic limit, but in opposite directions. This allows one to disentangle the distance to jamming and the distance to isostaticity. The picture that emerges is that most quantities are governed by the contact number and scale with the distance to isostaticity, while the contact number itself scales with the distance to jamming.

  8. Isostatic gravity map of the Point Sur 30 x 60 quadrangle and adjacent areas, California

    USGS Publications Warehouse

    Watt, J.T.; Morin, R.L.; Langenheim, V.E.

    2011-01-01

    This isostatic residual gravity map is part of a regional effort to investigate the tectonics and water resources of the central Coast Range. This map serves as a basis for modeling the shape of basins and for determining the location and geometry of faults in the area. Local spatial variations in the Earth's gravity field (after removing variations caused by instrument drift, earth-tides, latitude, elevation, terrain, and deep crustal structure), as expressed by the isostatic anomaly, reflect the distribution of densities in the mid- to upper crust, which in turn can be related to rock type. Steep gradients in the isostatic gravity field often indicate lithologic or structural boundaries. Gravity highs reflect the Mesozoic granitic and Franciscan Complex basement rocks that comprise both the northwest-trending Santa Lucia and Gabilan Ranges, whereas gravity lows in Salinas Valley and the offshore basins reflect the thick accumulations of low-density alluvial and marine sediment. Gravity lows also occur where there are thick deposits of low-density Monterey Formation in the hills southeast of Arroyo Seco (>2 km, Marion, 1986). Within the map area, isostatic residual gravity values range from approximately -60 mGal offshore in the northern part of the Sur basin to approximately 22 mGal in the Santa Lucia Range.

  9. Isostatic gravity map of the Death Valley ground-water model area, Nevada and California

    USGS Publications Warehouse

    Ponce, D.A.; Blakely, R.J.; Morin, R.L.; Mankinen, E.A.

    2001-01-01

    An isostatic gravity map of the Death Valley groundwater model area was prepared from over 40,0000 gravity stations as part of an interagency effort by the U.S. Geological Survey and the U.S. Department of Energy to help characterize the geology and hydrology of southwest Nevada and parts of California.

  10. CIDER PRESS, LOOKING SOUTHEAST ACROSS THE SCHUYLKILL RIVER. THIS PRESS, ...

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

    CIDER PRESS, LOOKING SOUTHEAST ACROSS THE SCHUYLKILL RIVER. THIS PRESS, CARVED OUT OF A LARGE BOULDER AT THE RIVERS EDGE, PROBABLY DATES FROM THE LIFETIME OF JOHN BARTRAM, IF NOT TO THE SWEDISH SETTLERS BEFORE HIM. THE IRON FENCE IS A NINETEENTH-CENTURY ADDITION - John Bartram House & Garden, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA

  11. PRESS SHOP. SEVEN BLISS PRESSES STAMP OUT A VARIETY OF ...

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

    PRESS SHOP. SEVEN BLISS PRESSES STAMP OUT A VARIETY OF CARTRIDGE AND SHELL CASINGS. THIS DEPARTMENT WAS TRANSFORMED FROM A MONEY-LOSING OPERATION TO A PROFIT CENTER UNDER THE FIRST WORKER-MANAGED QUALITY CIRCLE IN THE PLANT. - American Brass Foundry, 70 Sayre Street, Buffalo, Erie County, NY

  12. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    NASA Administrator Charles Bolden speaks during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  13. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    NASA Administrator Charles Bolden's reflection is seen in a TV monitor during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  14. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    Mike Gass, President and Chief Executive, United Launch Alliance is seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  15. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    Jane Poynter, President and Chair, Paragon Space Development Corp. is seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  16. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    Robert Millman of Blue Origin is seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  17. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    Brewster Shaw, VP and General Manager, NASA Systems, Boeing is seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  18. The CIA and the Press.

    ERIC Educational Resources Information Center

    Carvalho, Bernardo A.

    The involvement of the Central Intelligence Agency (CIA) with both United States and foreign news media has been recorded in numerous publications. This report reviews the important aspects of the CIA-press relationships as they have appeared in print and discusses the implications of these relationsihps for the credibility of the press. Media…

  19. Press Secretaries: A Brief Look.

    ERIC Educational Resources Information Center

    Rogers, Hines E., III

    The role of press secretary has attained a new significance during the past ten years because of presidential efforts to concentrate the focus of news on the White House. Originally intended to serve the public, the press secretary is now an important government official who not only conveys information but also explains and defends presidential…

  20. The Chilean Press Since Allende.

    ERIC Educational Resources Information Center

    Knudson, Jerry W.

    Based on interviews with 19 Chilean editors, government officials, heads of professional associations, and journalism education directors, this paper deals with the role of the press in Chile and with its future under the current military government. Following a review of the events concerning press control and censorship that followed the…

  1. Global isostatic geoid anomalies for plate and boundary layer models of the lithosphere

    NASA Technical Reports Server (NTRS)

    Hager, B. H.

    1981-01-01

    Commonly used one dimensional geoid models predict that the isostatic geoid anomaly over old ocean basins for the boundary layer thermal model of the lithosphere is a factor of two greater than that for the plate model. Calculations presented, using the spherical analogues of the plate and boundary layer thermal models, show that for the actual global distribution of plate ages, one dimensional models are not accurate and a spherical, fully three dimensional treatment is necessary. The maximum difference in geoid heights predicted for the two models is only about two meters. The thermal structure of old lithosphere is unlikely to be resolvable using global geoid anomalies. Stripping the effects of plate aging and a hypothetical uniform, 35 km, isostatically-compensated continental crust from the observed geoid emphasizes that the largest-amplitude geoid anomaly is the geoid low of almost 120 m over West Antarctica, a factor of two greater than the low of 60 m over Ceylon.

  2. Effective elastic thicknesses of the lithosphere and mechanisms of isostatic compensation in Australia

    NASA Technical Reports Server (NTRS)

    Zuber, Maria T.; Bechtel, Timothy D.; Forsyth, Donald W.

    1989-01-01

    The isostatic compensation of Australia is investigated using an isostatic model for the Australian lithosphere that assumes regional compensation of an elastic plate which undergoes flexure in response to surface and subsurface loading. Using the coherence between Bouguer gravity and topography and two separate gravity/topography data sets, it was found that, for the continent as a whole, loads with wavelengths above 1500 km are locally compensated. Loads with wavelengths in the range 600-1500 km are partially supported by regional stresses, and loads with wavelengths less than 600 km are almost entirely supported by the strength of the lithosphere. It was found that the predicted coherence for a flexural model of a continuous elastic plate does not provide a good fit to the observed coherence of central Australia. The disagreement between model and observations is explained.

  3. Degree variances of the earth's potential, topography and its isostatic compensation

    NASA Technical Reports Server (NTRS)

    Rapp, R. H.

    1982-01-01

    A spherical harmonic expansion of the earth's gravitational potential and equivalent rock topography to degree and order 180 is described. The potential implied by the topography considered as uncompensated and with isostatic compensation has been computed. Good agreement with the observed potential field is found when the depth of compensation in the Airy theory is assumed to be 50 km. At the higher degrees the correlation coefficient between the potential expansion and the equivalent rock topography is about 0.5. The Lachapelle equations for the topographic isostatic potential were tested using 1 x 1 deg equivalent rock topography. The degree variances agree at the lower degrees but at degree 36 the Lachapelle results using 5 deg data underestimate the potential degree variances by about one-third.

  4. Effective elastic thicknesses of the lithosphere and mechanisms of isostatic compensation in Australia

    NASA Technical Reports Server (NTRS)

    Zuber, Maria T.; Bechtel, Timothy D.; Forsyth, Donald W.

    1989-01-01

    The isostatic compensation of Australia is investigated using an isostatic model for the Australian lithosphere that assumes regional compensation of an elastic plate which undergoes flexure in response to surface and subsurface loading. Using the coherence between Bouguer gravity and topography and two separate gravity/topography data sets, it was found that, for the continent as a whole, loads with wavelengths above 1500 km are locally compensated. Loads with wavelengths in the range 600-1500 km are partially supported by regional stresses, and loads with wavelengths less than 600 km are almost entirely supported by the strength of the lithosphere. It was found that the predicted coherence for a flexural model of a continuous elastic plate does not provide a good fit to the observed coherence of central Australia. The disagreement between model and observations is explained.

  5. Large floor-fractured craters and isostatic crater modification: Implications for lithospheric thickness on Venus

    NASA Technical Reports Server (NTRS)

    Wichman, R. W.; Schultz, P. H.

    1993-01-01

    Several of the largest craters on Venus, including Mead, Meitner and Isabella, exhibit well-developed floor fracture patterns combining a central set of radial features with a peripheral set of concentric fractures. This pattern strongly resembles the fracture patterns observed in the largest floor-fractured craters on the Moon (e.g. Humboldt, Gauss, Petavius). Although most lunar floor-fractured craters apparently reflect crater modification by igneous intrusions and volcanism, we propose that the fractures in these larger craters represent domical flexure events in response to post-impact isostatic uplift. Since the extent of uplift and surface failure in this model depends on both the size of the basin cavity and the local lithospheric thickness, this interpretation also provides a means for constraining lithospheric thicknesses on Venus. Based on the apparent onset diameter of isostatic crater modification, we derive lithospheric thickness estimates for the Moon of approximately 80 - 100 km, and for Venus of approximately 50 - 70 km.

  6. Large floor-fractured craters and isostatic crater modification: Implications for lithospheric thickness on Venus

    NASA Astrophysics Data System (ADS)

    Wichman, R. W.; Schultz, P. H.

    1993-03-01

    Several of the largest craters on Venus, including Mead, Meitner and Isabella, exhibit well-developed floor fracture patterns combining a central set of radial features with a peripheral set of concentric fractures. This pattern strongly resembles the fracture patterns observed in the largest floor-fractured craters on the Moon (e.g. Humboldt, Gauss, Petavius). Although most lunar floor-fractured craters apparently reflect crater modification by igneous intrusions and volcanism, we propose that the fractures in these larger craters represent domical flexure events in response to post-impact isostatic uplift. Since the extent of uplift and surface failure in this model depends on both the size of the basin cavity and the local lithospheric thickness, this interpretation also provides a means for constraining lithospheric thicknesses on Venus. Based on the apparent onset diameter of isostatic crater modification, we derive lithospheric thickness estimates for the Moon of approximately 80 - 100 km, and for Venus of approximately 50 - 70 km.

  7. Isostatic gravity map with simplified geology of the Los Angeles 30 x 60 minute quadrangle

    USGS Publications Warehouse

    Wooley, R.J.; Yerkes, R.F.; Langenheim, V.E.; Chuang, F.C.

    2003-01-01

    This isostatic residual gravity map is part of the Southern California Areal Mapping Project (SCAMP) and is intended to promote further understanding of the geology in the Los Angeles 30 x 60 minute quadrangle, California, by serving as a basis for geophysical interpretations and by supporting both geological mapping and topical (especially earthquake) studies. Local spatial variations in the Earth's gravity field (after various corrections for elevation, terrain, and deep crustal structure explained below) reflect the lateral variation in density in the mid- to upper crust. Densities often can be related to rock type, and abrupt spatial changes in density commonly mark lithologic boundaries. The map shows contours of isostatic gravity overlain on a simplified geology including faults and rock types. The map is draped over shaded-relief topography to show landforms.

  8. Smoothing impact of isostatic crustal thickness models on local integral inversion of satellite gravity gradiometry data

    NASA Astrophysics Data System (ADS)

    Eshagh, Mehdi; Bagherbandi, Mohammad

    2011-10-01

    The effects of topographic masses on satellite gradiometric data are large and in order to reduce the magnitude of these effects some compensation mechanisms should be considered. Here we use the isostatic hypotheses of Airy-Heiskanen and the recent Vening Meinesz-Moritz for compensating these effects and to smooth the data prior to their downward continuation to gravity anomaly. The second-order partial derivatives of extended Stokes' formula are used for the continuations over a topographically rough territory like Persia. The inversions are performed and compared based on two schemes of the remove-compute-restore technique and direct downward continuation. Numerical results show that the topographic-isostatic effect based on Vening Meinesz-Mortiz's hypothesis smoothes the data better than that based on Airy-Heiskanen's hypothesis. Also the quality of inversions of the smoothed data by this mechanism is twice better than that of the nonsmoothed ones.

  9. The development of an isostatic gravitational model to degree 360 and its use in global gravity modelling

    NASA Astrophysics Data System (ADS)

    Pavlis, N. K.; Rapp, R. H.

    1990-03-01

    Consideration is given to the possibility of combining low-degree satellite-derived geopotential models with the harmonic coefficients of the topographic-isostatic potential implied by the Airy/Heiskanen isostatic hypothesis. The compilation of a topographic database providing information pertaining to terrain type classification is discussed. The formulation for the determination of harmonic coefficients of the topographic-isostatic potential is extended beyond to cases discussed by Lachapelle (1976) to include various terrain types. This formulation and the series expansion approach of Rummel et al. (1988) are implemented for potential coefficient determinations complete to degree and order 360. The topographic-isostatic coefficients are used with satellite-derived geopotential models to estimate mean gravity anomalies. The results are compared with observations to evaluate the quality of different estimation procedures.

  10. The development of an isostatic gravitational model to degree 360 and its use in global gravity modelling

    NASA Technical Reports Server (NTRS)

    Pavlis, N. K.; Rapp, R. H.

    1990-01-01

    Consideration is given to the possibility of combining low-degree satellite-derived geopotential models with the harmonic coefficients of the topographic-isostatic potential implied by the Airy/Heiskanen isostatic hypothesis. The compilation of a topographic database providing information pertaining to terrain type classification is discussed. The formulation for the determination of harmonic coefficients of the topographic-isostatic potential is extended beyond to cases discussed by Lachapelle (1976) to include various terrain types. This formulation and the series expansion approach of Rummel et al. (1988) are implemented for potential coefficient determinations complete to degree and order 360. The topographic-isostatic coefficients are used with satellite-derived geopotential models to estimate mean gravity anomalies. The results are compared with observations to evaluate the quality of different estimation procedures.

  11. A new method of computation of the isostatic anomaly and its application to the Rhine graben

    NASA Astrophysics Data System (ADS)

    Bernabe, Y.

    1981-11-01

    Using a preexisting mathematical model, a mathematical assumption of linearity is used to compute isostatic anomalies directly from geodetic and gravimetric data. When applied to the Rhine graben, the method yields satisfactory results which justify it a posteriori. The compensation depth is thought to be greater than 120 km. It is noted that the computation of a model of the distribution of compensation masses inside the earth necessitates further mathematical assumptions which make the results physically questionable.

  12. Isostaticity and Controlled Force Transmission in the Cytoskeleton: A Model Awaiting Experimental Evidence

    PubMed Central

    Blumenfeld, Raphael

    2006-01-01

    A new model is proposed for force transmission through the cytoskeleton (CSK). A general discussion is first presented on the physical principles that underlie the modeling of this phenomenon. Some fundamental problems of conventional models—continuous and discrete—are examined. It is argued that mediation of focused forces is essential for good control over intracellular mechanical signals. The difficulties of conventional continuous models in describing such mediation are traced to a fundamental assumption rather than to their being continuous. Relevant advantages and disadvantages of continuous and discrete modeling are discussed. It is concluded that favoring discrete models is based on two misconceptions, which are clarified. The model proposed here is based on the idea that focused propagation of mechanical stimuli in frameworks over large distances (compared to the mesh size) can only occur when considerable regions of the CSK are isostatic. The concept of isostaticity is explained and a recently developed continuous isostaticity theory is briefly reviewed. The model enjoys several advantages: it leads to good control over force mediation; it explains nonuniform stresses and action at a distance; it is continuous, making it possible to model force propagation over long distances; and it enables prediction of individual force paths. To be isostatic, or nearly so, CSK networks must possess specific structural characteristics, and these are quantified. Finally, several experimental observations are interpreted using the new model and implications are discussed. It is also suggested that this approach may give insight into the dynamics of reorganization of the CSK. Many of the results are amenable to experimental measurements, providing a testing ground for the proposed picture, and generic experiments are suggested. PMID:16912215

  13. Existence of isostatic, maximally random jammed monodisperse hard-disk packings.

    PubMed

    Atkinson, Steven; Stillinger, Frank H; Torquato, Salvatore

    2014-12-30

    We generate jammed packings of monodisperse circular hard-disks in two dimensions using the Torquato-Jiao sequential linear programming algorithm. The packings display a wide diversity of packing fractions, average coordination numbers, and order as measured by standard scalar order metrics. This geometric-structure approach enables us to show the existence of relatively large maximally random jammed (MRJ) packings with exactly isostatic jammed backbones and a packing fraction (including rattlers) of [Formula: see text]. By contrast, the concept of random close packing (RCP) that identifies the most probable packings as the most disordered misleadingly identifies highly ordered disk packings as RCP in 2D. Fundamental structural descriptors such as the pair correlation function, structure factor, and Voronoi statistics show a strong contrast between the MRJ state and the typical hyperstatic, polycrystalline packings with [Formula: see text] that are more commonly obtained using standard packing protocols. Establishing that the MRJ state for monodisperse hard disks is isostatic and qualitatively distinct from commonly observed polycrystalline packings contradicts conventional wisdom that such a disordered, isostatic packing does not exist due to a lack of geometrical frustration and sheds light on the nature of disorder. This prompts the question of whether an algorithm may be designed that is strongly biased toward generating the monodisperse disk MRJ state.

  14. Existence of isostatic, maximally random jammed monodisperse hard-disk packings

    PubMed Central

    Atkinson, Steven; Stillinger, Frank H.; Torquato, Salvatore

    2014-01-01

    We generate jammed packings of monodisperse circular hard-disks in two dimensions using the Torquato–Jiao sequential linear programming algorithm. The packings display a wide diversity of packing fractions, average coordination numbers, and order as measured by standard scalar order metrics. This geometric-structure approach enables us to show the existence of relatively large maximally random jammed (MRJ) packings with exactly isostatic jammed backbones and a packing fraction (including rattlers) of ϕ=0.826. By contrast, the concept of random close packing (RCP) that identifies the most probable packings as the most disordered misleadingly identifies highly ordered disk packings as RCP in 2D. Fundamental structural descriptors such as the pair correlation function, structure factor, and Voronoi statistics show a strong contrast between the MRJ state and the typical hyperstatic, polycrystalline packings with ϕ≈0.88 that are more commonly obtained using standard packing protocols. Establishing that the MRJ state for monodisperse hard disks is isostatic and qualitatively distinct from commonly observed polycrystalline packings contradicts conventional wisdom that such a disordered, isostatic packing does not exist due to a lack of geometrical frustration and sheds light on the nature of disorder. This prompts the question of whether an algorithm may be designed that is strongly biased toward generating the monodisperse disk MRJ state. PMID:25512529

  15. Crustal model for the Middle East and North Africa region: implications for the isostatic compensation mechanism

    NASA Astrophysics Data System (ADS)

    Seber, Dogan; Sandvol, Eric; Sandvol, Christine; Brindisi, Carrie; Barazangi, Muawia

    2001-12-01

    We present a new 3-D crustal model for the Middle East and North Africa region that includes detailed topography, sediment thickness, and Moho depth values. The model is obtained by collecting, integrating, and interpolating reliable, published sedimentary rock thickness and Moho depth measurements in the Middle East and North Africa region. To evaluate the accuracy of the model, the 3-D gravity response of the model is calculated and compared with available observed Bouguer gravity anomalies in the region. The gravity modelling shows that the new crustal model predicts large portions of the observed Bouguer anomalies. However, in some regions, such as the Red Sea and Caspian Sea regions, where crustal structure is relatively well-determined, the residual anomalies are of the order of a few hundred milligals. Since the new crustal model results in large residual anomalies in regions where reasonably good constraints exist for the model, these large residuals cannot simply be explained by inaccuracies in the model. To analyse the cause of these residuals further we developed an isostatically compensated (Airy-type) Moho-depth model and calculated its gravity response. Isostatic gravity anomalies are in nearly perfect agreement with the observed gravity values. However, the isostatic model differs significantly from the new (3-D) crustal model. If isostasy is to be maintained, crustal and/or upper mantle lateral density variations are needed to explain the large observed gravity residuals.

  16. A new approach to assess isostatic compensation of topography in continental domain from GOCE gravity gradients

    NASA Astrophysics Data System (ADS)

    Cadio, Cécilia; Saraswati, Anita; Cattin, Rodolphe; Mazzotti, Stéphane

    2016-11-01

    Estimating how topography is maintained provides insights into the different factors responsible for surface deformations and their relative roles. Here, we develop a new and simple approach to assess the degree of isostatic compensation of continental topography at regional scale from GOCE gravity gradients. We calculate the ratio between the radial gradient observed by GOCE and that calculated from topography only. From analytical and statistical formulations, simple relationships between this ratio and the degree of compensation are obtained under the Airy-Heiskanen isostasy hypothesis. Then, a value of degree of compensation at each point of study area can be easily deduced. We apply our method to the Alaska-Canada Cordillera and validate our results by comparison with a standard isostatic gravity anomaly model and additional geophysical information for this area. Both our GOCE-based results and the isostatic anomaly show that Airy-Heiskanen isostasy prevails for the Yukon Plateau whereas additional mechanisms are required to support topography below the Northwest Territories Craton and the Yakutat collision zone.

  17. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Expedition 21 Flight Engineer Jeffrey N. Williams answers questions from behind glass during a press conference on Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  18. Orion L-1 Press Conference

    NASA Image and Video Library

    2014-12-03

    In the Kennedy Space Center’s Press Site auditorium, members of the news media listen as agency and industry leaders updated progress as the Orion spacecraft and its Delta IV Heavy rocket were being prepared for launch.

  19. Hubble Servicing Mission Press Conference

    NASA Image and Video Library

    2009-04-22

    Mike Klenlen, the Hubble Deputy Project Manager, speaks during a press conference on the upcoming Hubble Space Telescope servicing mission, Thursday, April 23, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul. E. Alers)

  20. Hubble Servicing Mission Press Conference

    NASA Image and Video Library

    2009-04-22

    Preston Burch, Hubble Program Manager, speaks during a press conference on the upcoming Hubble Space Telescope servicing mission, Thursday, April 23, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul. E. Alers)

  1. The Press Research Centre, 1956-1976.

    ERIC Educational Resources Information Center

    Press Research Centre, Krakow (Poland).

    In 1956, the Press Research Centre was established in Cracow, Poland by a group of journalists and publishers, for the purpose of instituting press research that would have practical applications. The aims of the Centre were to conduct studies on the history of the Polish press, the contemporary press, press readership, and editorial techniques.…

  2. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    Assistant to the President for Science and Technology and Director of the White House Office of Science and Technology Policy Dr. John P. Holdren speaks during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  3. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    NASA Administrator Charles Bolden, left, and Assistant to the President for Science and Technology and Director of the White House Office of Science and Technology Policy Dr. John P. Holdren are seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  4. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    Mark Sirangelo, VP and Chair, SNC Space Systems Board, Sierra Nevada Corp. is seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  5. STS-102 Prelaunch Press Conference

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Joel Wells, NASA Public Affairs, introduces Ron Dittemore, NASA Shuttle Program Manager, Tommy Holloway, NASA International Space Station Program Manager, Dave King, NASA Director of Shuttle Processing, and Captain Clif Stargardt, US Air Force Meteorologist, in this STS-102 prelaunch press conference. The men give an overview of the prelaunch processing for the Discovery Orbiter (such as the PRSD loading) and give a weather forecast for launch. They then answer questions from the press.

  6. A comparison of impulse drying to double felted pressing on pilot- scale shoe presses and roll presses

    SciTech Connect

    Orloff, D.I.

    1992-08-01

    Pilot-scale shoe press and roll press experiments have been conducted to compare impulse drying and double felted pressing. Both ceramic coated and Beloit Type C press rolls have been evaluated. The experiments show that impulse drying can provide significantly higher outgoing solids than double felled pressing at the same impulse. For example, at an impulse of 0.234 MPa seconds (34 psi seconds), sheets at an ingoing solids of 52% were impulse dried (using the Beloit Type C press roll) to 68% solids while optimized double felled pressing could only yield press dryness of, at most, 60%.

  7. Investing in a Large Stretch Press

    NASA Technical Reports Server (NTRS)

    Choate, M.; Nealson, W.; Jay, G.; Buss, W.

    1986-01-01

    Press for forming large aluminum parts from plates provides substantial economies. Study assessed advantages and disadvantages of investing in large stretch-forming press, and also developed procurement specification for press.

  8. Spatial variations in isostatic compensation mechanisms of the Ninetyeast Ridge and their tectonic significance

    NASA Astrophysics Data System (ADS)

    Sreejith, K. M.; Krishna, K. S.

    2013-10-01

    Ninetyeast Ridge (NER), one of the longest linear volcanic features on the Earth, offers an excellent opportunity of understanding the isostatic response to the interactions of mantle plume with the migrating mid-ocean ridge. Bathymetry, geoid, and gravity (shipborne and satellite) data along 72 closely spaced transects and 17 overlapping grids on the NER are analyzed and modeled to determine the effective elastic thickness (Te) beneath the entire ridge. The results of 2-D and 3-D flexural modeling of the NER show large spatial variations in Te values ranging from 4 to 35 km, suggesting that the ridge was compensated along its length by different isostatic mechanisms. The southern (south of 22°S latitude) and northern (north of 2°N latitude) parts of the NER have Te values of >10 and >23 km, respectively, revealing that the southern part was emplaced on a lithosphere of intermediate strength possibly on flank of the Indian plate, whereas the northern part was emplaced in an intraplate setting. In contrast, in the central part of the NER (between latitudes 22°S and 2°N), highly variable Te values (4-22 km) are estimated. The scattered Te values in the central NER suggest that this part may have evolved due to the occurrence of frequent ridge jumps caused by the interaction of Kerguelen hot spot with rapid northward migration of the Wharton spreading ridge. Residual Mantle Bouguer Anomaly (RMBA) map of the NER and adjacent basins reveals that the entire length of the NER is associated with a significant negative anomaly up to 200 mGal, indicating the presence of thickened crust or less dense mantle beneath the ridge. 3-D crustal thickness map of the NER, generated by inversion of the RMBA data, shows a thick crust ranging from 15 to 19 km. The present study clearly shows that NER possesses a highly segmented isostatic pattern with the occurrence of subcrustal underplating or subsurface loading.

  9. Gravity inversion for rifted margin deep structure using extension and isostatic constraints

    NASA Astrophysics Data System (ADS)

    Condi, F. J.; Zelt, C. A.; Sawyer, D. S.; Hirasaki, G. J.

    1999-08-01

    We present a gravity inversion method for determining the deep structure of rifted margins. It uses a 2-D earth model parametrized as multiple, irregularly shaped, polygonal bodies, each of uniform density. The method has three novel features. First, it links parameters in the shallow parts of the model to those in the deep parts by using a uniform extension model as a constraint in the inversion. The shallow structure will typically be known with greater certainty than the deep structure from shallow seismic and borehole data. Second, it provides for variable weighting of prior information on densities, shapes, the extension model and smoothing to find geologically reasonable models. Third, it estimates densities and shapes simultaneously. The first two features are used to compensate for the inherent deficiencies of poor depth resolution and non-uniqueness in gravity modelling. The last two make the method an efficient way to explore a range of models. Synthetic tests of sensitivity to noise indicate that the isostatic extension constraint promotes the recovery of the short-wavelength Moho topography and eliminates spatial undulations in deep structure due to noise in the data. Synthetic tests of sensitivity to untrue prior information show that the isostatic extension constraint increases the range of acceptable recovered models over no isostatic extension constraint. The range of recovered Moho positions suggests a vertical resolution of about 2 km. Although many recovered models fit the data, the results imply a methodology for choosing a best set of models, and we suggest guidelines for applying the method to real margins.

  10. Plumes in the mantle. [free air and isostatic gravity anomalies for geophysical interpretation

    NASA Technical Reports Server (NTRS)

    Khan, M. A.

    1973-01-01

    Free air and isostatic gravity anomalies for the purposes of geophysical interpretation are presented. Evidence for the existance of hotspots in the mantle is reviewed. The prosposed locations of these hotspots are not always associated with positive gravity anomalies. Theoretical analysis based on simplified flow models for the plumes indicates that unless the frictional viscosities are several orders of magnitude smaller than the present estimates of mantle viscosity or alternately, the vertical flows are reduced by about two orders of magnitude, the plume flow will generate implausibly high temperatures.

  11. Ultra-stable isostatic bonded optical mount design for harsh environments

    NASA Astrophysics Data System (ADS)

    Pijnenburg, J.; te Voert, M. J. A.; de Vreugd, J.; Vosteen, A.; van Werkhoven, W.; Mekking, J.; Nijland, B. A. H.

    2012-09-01

    Through the years many stable optical mounts have been designed, analyzed and tested at TNO. This paper gives an overview of the design principles used. Various examples are presented together with verification test results. The use of adhesives in combination with an iso-static mount design allows mounting of optical components in a limited volume with limited deformation of the optical surfaces due to thermal and mechanical loads. Relatively large differences in thermal expansion over large temperature ranges can be overcome using a simple and predictable design at reasonable costs. Despite adhesives have limited dimensional stability and loadability, stable optical mounts can be realized when proper design principles are used.

  12. The combination of satellite and topographic/isostatic potential models for mean anomaly determinations

    NASA Astrophysics Data System (ADS)

    Rapp, Richard H.; Pavlis, Nikolaos

    A method is presented for the estimation of a global gravity anomaly field using the combination of satellite-derived potential coefficient models and the coefficients implied by the Airy-Heiskanen topographic/isostatic potential (Rummel et al., 1988) from topographic models with a 30-km depth of compensation. Gravity anomalies calculated with this method are compared with a terrestrial 1 x 1 degree anomaly file where the anomaly standard deviations were less than 10 mgals. Using the GEM T1 model (Marsh et al., 1988) to degree 36, the rms anomaly discrepency was + or - 19 mgals, while the rms values for the terrestrial anomalies was + or - 28 mgals.

  13. The combination of satellite and topographic/isostatic potential models for mean anomaly determinations

    NASA Technical Reports Server (NTRS)

    Rapp, Richard H.; Pavlis, Nikolaos

    1989-01-01

    A method is presented for the estimation of a global gravity anomaly field using the combination of satellite-derived potential coefficient models and the coefficients implied by the Airy-Heiskanen topographic/isostatic potential (Rummel et al., 1988) from topographic models with a 30-km depth of compensation. Gravity anomalies calculated with this method are compared with a terrestrial 1 x 1 degree anomaly file where the anomaly standard deviations were less than 10 mgals. Using the GEM T1 model (Marsh et al., 1988) to degree 36, the rms anomaly discrepency was + or - 19 mgals, while the rms values for the terrestrial anomalies was + or - 28 mgals.

  14. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    From left, Jane Poynter, President and Chair, Paragon Space Development Corp., Brewster Shaw, VP and General Manager, NASA Systems, Boeing, Robert Millman of Blue Origin and Mike Gass, President and Chief Executive, United Launch Alliance are seen during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  15. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    NASA Administrator Charles Bolden listens to his introduction by Assistant to the President for Science and Technology and Director of the White House Office of Science and Technology Policy Dr. John P. Holdren during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  16. Apollo 13 Facts: Press Conference

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Flight Director Gene Krantz gives an overview of the Apollo 13 mission as corrections are made in the power down checklist, passive thermal control, and orbital burns after the spacecraft runs into problems. He then answers questions from the press with the help of Tony England, Bill Peters, and Dick Thorson. Footage then shows newspaper headlines 'We're Not Concerned' and 'Getting Ready to Land' as people watch televisions to see if the astronauts landed safely. The press conference section of this video has sound, the headlines section does not.

  17. Apollo 13 Facts: Press Conference

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Flight Director Gene Krantz gives an overview of the Apollo 13 mission as corrections are made in the power down checklist, passive thermal control, and orbital burns after the spacecraft runs into problems. He then answers questions from the press with the help of Tony England, Bill Peters, and Dick Thorson. Footage then shows newspaper headlines 'We're Not Concerned' and 'Getting Ready to Land' as people watch televisions to see if the astronauts landed safely. The press conference section of this video has sound, the headlines section does not.

  18. Automation of a laboratory particleboard press

    Treesearch

    Robert L. Geimer; Gordon H. Stevens; Richard E. Kinney

    1982-01-01

    A manually operated particleboard press was converted to a fully automatic, programable system with updated data collection capabilities. Improved control has permitted observations of very small changes in pressing variables resulting in the development of a technique capable of reducing press times by 70 percent. Accurate control of the press is obtained through an...

  19. 7 CFR 550.29 - Press releases.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Press releases. 550.29 Section 550.29 Agriculture... Program Management § 550.29 Press releases. Press releases or other forms of public notification will be... opportunity to review, in advance, all written press releases and any other written information to be...

  20. Rainbow over the Press Site

    NASA Image and Video Library

    2014-11-10

    As rain showers dissipate, a rainbow appeared over the Kennedy Space Center's Press Site and turn basin. In the foreground is the historic countdown clock. In the background, is Launch Pad 39B where agency's Space Launch System will launch astronauts aboard the Orion spacecraft to deep-space destinations such as an asteroid and Mars.

  1. The Schools and the Press.

    ERIC Educational Resources Information Center

    Lewis, Ann Chambers

    This book acquaints the school administrator with the need for good press relations and suggests ways to obtain such relations. A brief overview of the internal workings and concerns of a newspaper staff is presented. Methods of writing news copy for release and how to time releases for maximum news coverage are explained. Throughout the volume,…

  2. Censorship and the Student Press.

    ERIC Educational Resources Information Center

    Oettinger, Lauren

    The First Amendment rights provided to journalists--freedom of speech and of the press--are fundamental beliefs held by Americans. What students learn in the government class, however, may not be what they learn as editors-in-chief of student newspapers. U.S. schools are being charged with the censorship of student publications at an…

  3. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Spaceflight Participant Guy Laliberté, left, and Expedition 21 Flight Engineer Maxim Suraev, talk to each other at the start of the press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  4. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Spaceflight Participant Guy Laliberté, left, Expedition 21 Flight Engineer Maxim Suraev, center, and Expedition 21 Flight Engineer Jeffrey N. Williams wave hello and point to members of their families at the start of the press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  5. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Spaceflight Participant Guy Laliberté, left, Expedition 21 Flight Engineer Maxim Suraev, center, and Expedition 21 Flight Engineer Jeffrey N. Williams pose for a group photograph at the end of the press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  6. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Backup Spaceflight Participant Barbara Barrett, left, backup Expedition 21 Commander Aleksandr Skvortsov, center, and backup Expedition 21 Flight Engineer Shannon Walker are seen during a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  7. Gifted Education Press Quarterly, 1995.

    ERIC Educational Resources Information Center

    Fisher, Maurice D., Ed.

    1995-01-01

    This document consists of the four issues of the newsletter "Gifted Education Press Quarterly" published during 1995. This newsletter addresses issues in the education of gifted children and youth. The major articles are: (1) "Using Today's Technology: Parents Can Help Challenge Gifted Children" (Adrienne O'Neill); (2)…

  8. The Alternative Press in Microform.

    ERIC Educational Resources Information Center

    Tsang, Daniel C.

    Presented is an analysis of what has been done regarding the preservation of alternative publications in microfilm. The alternative press was defined, for the purposes of this study, as "nonstandard, nonestablishment publications." Two projects undertaken to microfilm such publications, one by the Microphoto Division of Bell and Howell…

  9. Law and the Student Press.

    ERIC Educational Resources Information Center

    Stevens, George E.; Webster, John B.

    Court cases and legal decisions involving the student press in the late 1960s and early 1970s are brought together in this book in order to show how the law has been applied to school officials and student journalists in high school, college, and the underground. The ten chapters cover the following topics: censorship, libel, obscenity, contempt,…

  10. Mars Observer Press Conference JPL

    NASA Astrophysics Data System (ADS)

    1993-08-01

    The Mars Observer mission spacecraft was primarily designed for exploring Mars and the Martian environment. The Mars Observer was launched on September 25, 1992. The spacecraft was lost in the vicinity of Mars on August 21, 1993 when the spacecraft began its maneuvering sequence for Martian orbital insertion. This videotape shows a press briefing, held after the spacecraft had not responded to attempts to communicate with it, to explain to the press the problems and the steps that were being taken to re-establish communication with the spacecraft. The communications had been shutdown prior to the orbital insertion burn to protect the instruments. At the time of the press conference, the communications system was still not operational, and attempts were being made to re-establish communication. Bob McMillan of the Public Affairs Office at JPL gives the initial announcement of the continuing communication problem with the spacecraft. Mr. McMillan introduces William Piotrowski, acting director of solar system exploration, who reiterates that there is indeed no communication with the Observer spacecraft. He is followed by Glenn Cunningham, the Project Manager of the Mars Observer who speaks about the attempts to re-establish contact. Mr. Cunningham is followed by Satenios Dallas, the Mission Manager for the Mars Observer Project, who speaks about the sequence of events leading up to the communication failure, and shows an animated video presenting the orbital insertion maneuvers. The briefing was then opened up for questions from the assembled press, both at JPL and at the other NASA Centers. The questions are about the possible reasons for the communication failure, and the attempts to restore communications with the spacecraft. Dr. Arden L. Albee, chief scientist for the Mars Observer Mission, joins the other panel members to answer questions. At the end of the press briefing the animation of the Mars orbital insertion is shown again.

  11. Mars Observer Press Conference JPL

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Mars Observer mission spacecraft was primarily designed for exploring Mars and the Martian environment. The Mars Observer was launched on September 25, 1992. The spacecraft was lost in the vicinity of Mars on August 21, 1993 when the spacecraft began its maneuvering sequence for Martian orbital insertion. This videotape shows a press briefing, held after the spacecraft had not responded to attempts to communicate with it, to explain to the press the problems and the steps that were being taken to re-establish communication with the spacecraft. The communications had been shutdown prior to the orbital insertion burn to protect the instruments. At the time of the press conference, the communications system was still not operational, and attempts were being made to re-establish communication. Bob McMillan of the Public Affairs Office at JPL gives the initial announcement of the continuing communication problem with the spacecraft. Mr. McMillan introduces William Piotrowski, acting director of solar system exploration, who reiterates that there is indeed no communication with the Observer spacecraft. He is followed by Glenn Cunningham, the Project Manager of the Mars Observer who speaks about the attempts to re-establish contact. Mr. Cunningham is followed by Satenios Dallas, the Mission Manager for the Mars Observer Project, who speaks about the sequence of events leading up to the communication failure, and shows an animated video presenting the orbital insertion maneuvers. The briefing was then opened up for questions from the assembled press, both at JPL and at the other NASA Centers. The questions are about the possible reasons for the communication failure, and the attempts to restore communications with the spacecraft. Dr. Arden L. Albee, chief scientist for the Mars Observer Mission, joins the other panel members to answer questions. At the end of the press briefing the animation of the Mars orbital insertion is shown again.

  12. Geoid determination with density hypotheses from isostatic models and geological information

    NASA Astrophysics Data System (ADS)

    Kuhn, M.

    2003-05-01

    Geoid determination by Stokes's formula requires a complete knowledge of the topographical mass density distribution in order to perform gravity reductions to the geoid boundary. However, deeper masses are also of interest, in order to produce a smooth field of gravity anomalies which will improve results from interpolation procedures. Until now, in most cases a constant mass density has been considered, which is a very rough approximation of reality. The influence on the geoid height coming from different mass density hypotheses given by the isostatic models of Pratt/Hayford, Airy/Heiskanen and Vening Meinesz is studied. Apart from a constant mass density value, additional density information deduced from geological maps and thick sedimentary layers is considered. An overview of how mass density distributions act within Stokes's theory is given. The isostatic models are considered in spherical and planar approximation, as well as with constant and lateral variable mass density of the topographical and deeper masses. Numerical results in a test area in south-west Germany show that the differences in the geoid height due to different density hypotheses can reach a magnitude of more than 1 decimetre, which is not negligible in a precise geoid determination with centimetre accuracy.

  13. Comparisons of global topographic/isostatic models to the Earth's observed gravity field

    NASA Astrophysics Data System (ADS)

    Rummel, Reiner; Rapp, Richard H.; Suenkel, Hans; Tscherning, C. Christian

    1988-03-01

    The Earth's gravitational potential, as described by a spherical harmonic expansion to degree 180, was compared to the potential implied by the topography and its isostatic compensation using five different hypothesis. Initially, series expressions for the Airy/Heiskanen topographic isostatic model were developed to the third order in terms of (h/R), where h is equivalent rock topography and R is a mean Earth radius. Using actual topographic developments for the Earth, it was found that the second and third terms of the expansion contributed 30 and 3 percents, of the first of the expansion. With these new equations it is possible to compute depths (D) of compensation, by degree, using 3 different criteria. The results show that the average depth implied by criterion I is 60 km while it is about 33 km for criteria 2 and 3 with smaller compensation depths at the higher degrees. Another model examined was related to the Vening-Meinesz regional hypothesis implemented in the spectral domain. Finally, oceanic and continental response functions were derived for the global data sets and comparisons made to locally determined values.

  14. Comparisons of global topographic/isostatic models to the Earth's observed gravity field

    NASA Technical Reports Server (NTRS)

    Rummel, Reiner; Rapp, Richard H.; Suenkel, Hans; Tscherning, C. Christian

    1988-01-01

    The Earth's gravitational potential, as described by a spherical harmonic expansion to degree 180, was compared to the potential implied by the topography and its isostatic compensation using five different hypothesis. Initially, series expressions for the Airy/Heiskanen topographic isostatic model were developed to the third order in terms of (h/R), where h is equivalent rock topography and R is a mean Earth radius. Using actual topographic developments for the Earth, it was found that the second and third terms of the expansion contributed 30 and 3 percents, of the first of the expansion. With these new equations it is possible to compute depths (D) of compensation, by degree, using 3 different criteria. The results show that the average depth implied by criterion I is 60 km while it is about 33 km for criteria 2 and 3 with smaller compensation depths at the higher degrees. Another model examined was related to the Vening-Meinesz regional hypothesis implemented in the spectral domain. Finally, oceanic and continental response functions were derived for the global data sets and comparisons made to locally determined values.

  15. Isostatic gravity map of the Monterey 30 x 60 minute quadrangle and adjacent areas, California

    USGS Publications Warehouse

    Langenheim, V.E.; Stiles, S.R.; Jachens, R.C.

    2002-01-01

    The digital dataset consists of one file (monterey_100k.iso) containing 2,385 gravity stations. The file, monterey_100k.iso, contains the principal facts of the gravity stations, with one point coded per line. The format of the data is described below. Each gravity station has a station name, location (latitude and longitude, NAD27 projection), elevation, and an observed gravity reading. The data are on the IGSN71 datum and the reference ellipsoid is the Geodetic Reference System 1967 (GRS67). The free-air gravity anomalies were calculated using standard formulas (Telford and others, 1976). The Bouguer, curvature, and terrain corrections were applied to the free-air anomaly at each station to determine the complete Bouguer gravity anomalies at a reduction density of 2.67 g/cc. An isostatic correction was then applied to remove the long-wavelength effect of deep crustal and/or upper mantle masses that isostatically support regional topography.

  16. Constrained optimisation of the parameters for a simple isostatic Moho model

    NASA Astrophysics Data System (ADS)

    Lane, R. J.

    2010-12-01

    In a regional-scale integrated 3D crustal mapping project for the offshore Capel-Faust region, approximately 800 km east of the Australian east coast, gravity data were being used by the Geoscience Australia Remote Eastern Frontiers team to evaluate the viability of an interpretation of the upper crustal sequence that had been derived from a network of 2D seismic lines. A preliminary gravity forward modelling calculation for this sequence using mass density values derived from limited well log and seismic velocity information indicated a long wavelength misfit between this response and the observed data. Rather than draw upon a mathematical function to account for this component of the model response (e.g., low order polynomial), a solution that would lack geological significance, I chose to first investigate whether the gravity response stemming from the density contrast across the crust-mantle boundary (i.e., the Moho) could account for this misfit. The available direct observations to build the Moho surface in the 3D geological map were extremely sparse, however. The 2D seismic data failed to provide any information on the Moho. The only constraints on the depth to this interface within the project area were from 2 seismic refraction soundings. These soundings were in the middle of a set of 11 soundings forming a profile across the Lord Howe Rise. The use of relatively high resolution bathymetry data coupled with an Airy-Heiskanen isostatic model assumption was investigated as a means of defining the form of the Moho surface. The suitability of this isostatic assumption and associated simple model were investigated through optimisation of the model parameters. The Moho depths interpreted from the seismic refraction profile were used as the observations in this exercise. The output parameters were the average depth to the Moho (Tavg), upper crust density (RHOzero), and density contrast across the lower crust and upper mantle (RHOone). The model inputs were a grid

  17. Commercial Human Spaceflight Press Conference

    NASA Image and Video Library

    2010-02-02

    From left, Ken Bowersox, VP Astronaut Safety, SpaceX, David Thompson, CEO, Orbital Science Corporation, Mark Sirangelo, VP and Chair, SNC Space Systems Board, Sierra Nevada Corp., NASA Administrator Charles Bolden, Assistant to the President for Science and Technology and Director of the White House Office of Science and Technology Policy Dr. John P. Holdren, Jane Poynter, President and Chair, Paragon Space Development Corp., Brewster Shaw, VP and General Manager, NASA Systems, Boeing, Robert Millman of Blue Origin, and, Mike Gass, President and Chief Executive, United Launch Alliance, pose for a group photo during a press conference, Tuesday, Feb. 2, 2010, at the National Press Club in Washington, where it was announced that NASA has awarded $50 million through funded agreements to further the commercial sector's capability to support transport of crew to and from low Earth orbit. Photo Credit: (NASA/Bill Ingalls)

  18. Orion Post Scrub Press Conference

    NASA Image and Video Library

    2014-12-04

    In the Kennedy Space Center’s Press Site auditorium, agency and industry leaders spoke to members of the news media about the postponement of the Orion Flight Test launch due to an issue related to fill and drain valves on the Delta IV Heavy rocket. From left are: Brandi Dean of NASA Public Affairs, Mark Geyer, NASA's Orion program manager, Mike Hawes, Lockheed Martin Orion Program manager, and Dan Collins, United Launch Alliance chief operating officer.

  19. Expedition 24 Prelaunch Press Conference

    NASA Image and Video Library

    2010-06-13

    Expedition 24 European Space Agency back-up crew member Paolo Nespoli listens to a reporter’s question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Monday, June 14, 2010. The launch of the Soyuz spacecraft with Expedition 24 NASA Flight Engineers Shannon Walker and Douglas Wheelock, and Soyuz Commander Fyodor Yurchikhin is scheduled for Wednesday, June 16, 2010 at 3:35 a.m. Kazakhstan time. Photo Credit: (NASA/Carla Cioffi)

  20. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition Flight Engineer Timothy J. Creamer, left, Soyuz Commander Oleg Kotov of Russia, center, and Flight Engineer Soichi Noguchi of the Japan listen to a reporter's question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Creamer, Kotov, and Noguchi, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  1. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Expedition 21 Flight Engineer Maxim Suraev, left, answers a reporter's question while looking at Expedition 21 Flight Engineer Jeffrey N. Williams during a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Suraev is scheduled to launch onboard a Soyuz rocket to the International Space Station (ISS) with Williams and Spaceflight Participant Guy Laliberté on Wednesday, Sept. 30, 2009 from the Baikonur Cosmodrome in Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  2. Expedition 24 Prelaunch Press Conference

    NASA Image and Video Library

    2010-06-13

    Expedition 24 Flight Engineer Doug Wheelock, left, answers a reporter’s question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, while Soyuz Commander Fyodor Yurchikhin looks on, Monday, June 14, 2010. The launch of the Soyuz spacecraft with Expedition 24 NASA Flight Engineers Shannon Walker and Douglas Wheelock, and Soyuz Commander Fyodor Yurchikhin is scheduled for Wednesday, June 16, 2010 at 3:35 a.m. Kazakhstan time. Photo Credit: (NASA/Carla Cioffi)

  3. Expedition 31 Crew Press Conference

    NASA Image and Video Library

    2012-05-14

    Quarantined Expedition 31 Flight Engineer Joe Acaba answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Monday, May 14, 2012 in Baikonur, Kazakhstan. The launch of the Soyuz spacecraft with Acaba, Soyuz Commander Gennady Padalka, and Flight Engineer Sergei Revin is scheduled for 9:01 a.m. local time on Tuesday, May 15. Photo Credit (NASA/Bill Ingalls)

  4. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Expedition 21 Flight Engineer Jeffrey N. Williams listens to a reporter's question at a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Williams is scheduled to launch onboard a Soyuz rocket to the International Space Station (ISS) with Expedition 21 Flight Engineer Maxim Suraev and Spaceflight Participant Guy Laliberté on Wednesday, Sept. 30, 2009 from the Baikonur Cosmodrome in Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  5. Expedition 31 Crew Press Conference

    NASA Image and Video Library

    2012-05-14

    Quarantined Expedition 31 Soyuz Commander Gennady Padalka answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Monday, May 14, 2012 in Baikonur, Kazakhstan. The launch of the Soyuz spacecraft with Padalka, Flight Engineer Sergei Revin of Russia, and prime NASA Flight Engineer Joe Acaba is scheduled for 9:01 a.m. local time on Tuesday, May 15. Photo Credit (NASA/Bill Ingalls)

  6. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Spaceflight Participant Guy Laliberté answers reporters questions at a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Liberté is scheduled to launch with Expedition 21 Flight Engineer Maxim Suraev and Expedition 21 Flight Engineer Jeffrey N. Williams on Wednesday, Sept. 30, 2009 from the Baikonur Cosmodrome in Kazakhstan on a Soyuz TMA-16 spacecraft. Photo Credit: (NASA/Bill Ingalls)

  7. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Expedition 21 Flight Engineer Maxim Suraev listens to a reporter's question at a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Suraev is scheduled to launch onboard a Soyuz rocket to the International Space Station (ISS) with Expedition 21 Flight Engineer Jeffrey N. Williams and Spaceflight Participant Guy Laliberté on Wednesday, Sept. 30, 2009 from the Baikonur Cosmodrome in Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  8. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 NASA Flight Engineer Timothy J. Creamer answers a reporter's question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  9. Expedition 31 Crew Press Conference

    NASA Image and Video Library

    2012-05-14

    Quarantined Expedition 31 Flight Engineer Sergei Revin of Russia answers reporters questions from behind glass during a prelaunch press conference held at the Cosmonaut Hotel on Monday, May 14, 2012 in Baikonur, Kazakhstan. The launch of the Soyuz spacecraft with Revin, Soyuz Commander Gennady Padalka, and NASA Flight Engineer Joe Acaba is scheduled for 9:01 a.m. local time on Tuesday, May 15. Photo Credit (NASA/Bill Ingalls)

  10. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Spaceflight Participant Guy Laliberté holds a red clown nose while answering reporters' questions at a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Laliberté is scheduled to launch with Expedition 21 Flight Engineer Maxim Suraev and Expedition 21 Flight Engineer Jeffrey N. Williams on Wednesday, Sept. 30, 2009 from the Baikonur Cosmodrome in Kazakhstan on a Soyuz TMA-16 spacecraft. Photo Credit: (NASA/Bill Ingalls)

  11. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Expedition 21 Flight Engineer Jeffrey N. Williams answers a reporter's question during a press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Williams is scheduled to launch onboard a Soyuz rocket to the International Space Station (ISS) with Expedition 21 Flight Engineer Maxim Suraev and Spaceflight Participant Guy Laliberté on Wednesday, Sept. 30, 2009 from the Baikonur Cosmodrome in Kazakhstan. Photo Credit: (NASA/Bill Ingalls)

  12. Expedition 23 Prelaunch Press Conference

    NASA Image and Video Library

    2010-03-31

    Expedition 23 Flight Engineer Mikhail Kornienko answers a reporters' question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan on Thursday, April 1, 2010. The launch of the Soyuz spacecraft with Expedition 23 NASA Flight Engineer Mikhail Kornienko, Soyuz Commander Alexander Skvortsov and Flight Engineer Tracy Caldwell Dyson is scheduled for Friday, April 2, 2010 at 10:04 a.m. Kazakhstan time. Photo Credit: (NASA/Bill Ingalls)

  13. Antares Post Launch Press Conference

    NASA Image and Video Library

    2013-09-18

    Frank Culbertson, executive vice president, Orbital Sciences Corporation, talks during a press conference held after the successful launch of the Antares rocket, with the Cygnus cargo spacecraft aboard, Wednesday, Sept. 18, 2013, NASA Wallops Flight Facility, Virginia. Cygnus is on its way to rendezvous with the space station. The spacecraft will deliver about 1,300 pounds (589 kilograms) of cargo, including food and clothing, to the Expedition 37 crew. Photo Credit: (NASA/Bill Ingalls)

  14. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 Flight Engineer Soichi Noguchi answers a reporter's question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  15. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 Soyuz Commander Oleg Kotov listens to a reporter's question during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  16. STS-97 Prelaunch Press Conference

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Bruce Buckingham, NASA Public Affairs, introduces Ron Dittemore, NASA Shuttle Program Manager, Bob Cabana, International Space Station (ISS) Manager, International Operations, NASA, Michael Vachon, Canadian Space Agency, David King, NASA Director of Shuttle Processing, and Lieutenant Ken Ferland, 45th Weather Squadron, US Air Force. They each give a brief statement on the STS-97 Endeavour mission, launch, and weather status and answer questions from the press.

  17. Apollo 11 preflight press conference

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The three prime crewmen of the Apollo 11 lunar landing mission participate in a pre-flight press conference in the bldg 1 auditorium on July 5, 1969. Left to right, are Astronauts Neil A. Armstrong, commander; Edwin E. Aldrin Jr., lunar module pilot; and Michael Collins, command module pilot. The box-like enclosure surrounding the three astronauts was part of elaborate precautions in effect to reduce the possibility of exposing the crewmen to infectious disease in the preflight period.

  18. Press Conference - First Gemini Astronauts

    NASA Image and Video Library

    1964-04-13

    S64-19466 (13 April 1964) --- A press conference was held in the Bldg. 1 auditorium at the NASA Manned Spacecraft Center to announce the first Gemini astronaut selections. Shown left to right are Paul Haney, MSC Public Affairs Officer (standing); astronauts Walter Schirra and Thomas Stafford; Dr. Robert Gilruth, director of MSC; astronauts Virgil Grissom and John Young; and Donald K. Slayton, assistant director of Flight Crew Operations at MSC.

  19. Antares Post Launch Press Conference

    NASA Image and Video Library

    2013-09-18

    Alan Lindenmoyer, program manager, NASA's Commercial Crew and Cargo Program, talks during a press conference held after the successful launch of the Orbital Sciences Corporation Antares rocket, with the Cygnus cargo spacecraft aboard, Wednesday, Sept. 18, 2013, NASA Wallops Flight Facility, Virginia. Cygnus is on its way to rendezvous with the space station. The spacecraft will deliver about 1,300 pounds (589 kilograms) of cargo, including food and clothing, to the Expedition 37 crew. Photo Credit: (NASA/Bill Ingalls)

  20. Hubble Servicing Mission Press Conference

    NASA Image and Video Library

    2009-04-22

    Ed Weiler, Associate Administrator, Science Mission Directorate at NASA Headquarters, seated second from left, speaks during a press conference on the upcoming Hubble Space Telescope servicing mission as David Leckrone, Hubble Project Scientist, Preston Burch and Mike Klenlen, seated right, look on, Thursday, April 23, 2009, at NASA Headquarters in Washington. J.D. Harrington, Public Affairs officer for the Science Mission Directorate looks on at left. Photo Credit: (NASA/Paul. E. Alers)

  1. Investigation of the High-Cycle Fatigue Life of Selective Laser Melted and Hot Isostatically Pressed Ti-6Al-4v

    DTIC Science & Technology

    2015-03-26

    from Figures 3 and 4 were first modeled in SolidWorks to produce a 3D CAD model. The model was then exported from SolidWorks in a STEP file format ...subcommittees. As of 2014, these subcommittees have published standards in the areas of materials and processes, terminology, design and data formats , and...plate and process the STEP file into an EOS SLI file format used for the DMLS process. The SLI format slices the 3D model into printable 2D layers

  2. Microstructural formation during hot isostatic pressing and heat treatment of EP741NP Ni-base superalloy, and the effect of the microstructure on mechanical properties

    SciTech Connect

    Fatkullin, O.Kh.; Yeriomenko, V.I.; Vlasova, O.N.; Korneyeva, N.N.; Grits, N.M.

    1996-12-31

    The structure and mechanical properties of highly-alloyed EP741NP superalloy in various conditions of HIP, isothermal forging and heat treatment were examined and tested. HIP`ing temperature has an influence on the structure and mechanical properties of the EP741NP superalloy. Microstructures and room and working temperature mechanical-properties of EP741NP superalloy after HIP carried out at the temperature of the complete dissolution of the {gamma}-phase, and temperatures in two- and single phase fields are shown. Problems concerning structure development in EP741NP superalloy mill products produced by PM technique followed by isothermal forging are discussed. Necklace structure and fine-grained microstructures developed in mill products produced by different techniques are examined. An advantage of the isothermal upsetting of extruded bars is shown. Parameters of the microstructure formed in the mill products produced by this technique and heat treated under optimum conditions ensuring high level of strength and high-temperature strength are studied.

  3. FY16 Annual Accomplishments - Waste Form Development and Performance: Evaluation Of Ceramic Waste Forms - Comparison Of Hot Isostatic Pressed And Melt Processed Fabrication Methods

    SciTech Connect

    Amoroso, J.; Dandeneau, C.

    2016-10-13

    FY16 efforts were focused on direct comparison of multi-phase ceramic waste forms produced via melt processing and HIP methods. Based on promising waste form compositions previously devised at SRNL, simulant material was prepared at SRNL and a portion was sent to the Australian Nuclear Science and Technology Organization (ANSTO) for HIP treatments, while the remainder of the material was melt processed at SRNL. The microstructure, phase formation, elemental speciation, and leach behavior, and radiation stability of the fabricated ceramics was performed. In addition, melt-processed ceramics designed with different fractions of hollandite, zirconolite, perovskite, and pyrochlore phases were investigated. for performance and properties.

  4. Microstructure of Dense Thin Sheets of gamma-TiAl Fabricated by Hot Isostatic Pressing of Tape-Cast Monotapes (Preprint)

    DTIC Science & Technology

    2007-02-01

    near-gamma microstructure during HIPing. Chemical analysis revealed that the dense sheet had a carbon content of 0.13 wt.%, which was only 0.04 wt...powder transformed to the equilibrium near-γ microstructure during HIPing. Chemical analysis revealed that the dense sheet had a carbon content of...thermomechanical processing of ingot or powder metallurgy material at temperatures above 1100oC. The ASRP is a modified pack-rolling process pioneered

  5. Effect of heat treatment and in vitro aging on the microstructure and mechanical properties of cold isostatic-pressed zirconia ceramics for dental restorations.

    PubMed

    Vatali, Anna; Kontonasaki, Eleana; Kavouras, Panagiotis; Kantiranis, Nikolaos; Papadopoulou, Lambrini; Paraskevopoulos, Konstantinos K M; Koidis, Petros

    2014-10-01

    The temperature variations during the veneering firing cycles of a zirconia dental ceramic can negatively affect its mechanical properties. A possible synergistic effect of both heat-treatment and aging while exposed to the oral environment could result to catastrophic failure. The aim of the present study was to investigate the effect of heat treatment followed during veneering and in vitro aging on the mechanical and microstructural properties of zirconia dental ceramics. Three specimens from each of two zirconia blocks (Ivoclar IPS e.max ZirCAD (IV) and Wieland ZENO Zr (WI)) were cut by CAD/CAM technology, fully sintered and polished. Each one was cut in four equal parts. One part was used as control (C), one was heat-treated (H), one was aged (A) (134°C, 2bar, 10h) and one was heat-treated and subsequently aged (HA). The mechanical properties (nano-hardness (H) and elastic modulus (E*)) were investigated by nano-indentation tests while the surface characterization was carried out with XRD, FTIR and SEM. Different treatments on IV and WI samples resulted in a reduction of both H and E* values, however the differences were not statistically significant (p>0.05). The combination of treatments imposes an overall effect (p<0.001), enhancing the influence on both H and E* values. This reduction in mechanical properties was followed by an increase of monoclinic content. Greater variations in both H and E* values were recorded for WI samples. The clinical performance of zirconia dental ceramics may be affected during firing and aging resulting in increased probability of failure. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. An isostatic study of the Karoo basin and underlying lithosphere in 3-D

    NASA Astrophysics Data System (ADS)

    Scheiber-Enslin, Stephanie E.; Ebbing, Jörg; Webb, Susan J.

    2016-08-01

    A 3-D density model of the crust and upper mantle beneath the Karoo basin is presented here. The model is constrained using potential field, borehole and seismic data. Uplift of the basin by the end of the Cretaceous has resulted in an unusually high plateau (>1000 m) covering a large portion of South Africa. Isostatic studies show the topography is largely compensated by changes in Moho depths (˜35 km on-craton and >45 km off-craton) and changes in lithospheric mantle densities between the Kaapvaal Craton and surrounding regions (˜50 kg m-3 increase from on- to off-craton). This density contrast is determined by inverted satellite gravity and gravity gradient data. The highest topography along the edge of the plateau (>1200 m) and a strong Bouguer gravity low over Lesotho, however, can only be explained by a buoyant asthenosphere with a density decrease of around 40 kg m-3.

  7. Incomplete separability of Antarctic plate rotation from glacial isostatic adjustment deformation within geodetic observations

    NASA Astrophysics Data System (ADS)

    King, Matt A.; Whitehouse, Pippa L.; van der Wal, Wouter

    2016-01-01

    Geodetic measurements of Antarctic solid Earth deformation include signals from plate rotation and glacial isostatic adjustment (GIA). Through simulation, we investigate the degree to which these signals are separable within horizontal GPS site velocities that commonly define plate rotation estimates and that promise new constraints on models of GIA. Using a suite of GIA model predictions that incorporate both 1-D and 3-D Earth rheologies, we show that, given the present location of GPS sites within East Antarctica, unmodelled or mismodelled GIA signal within GPS velocities produces biased estimates of plate rotation. When biased plate rotation is removed from the GPS velocities, errors as large as 0.8 mm yr-1 are introduced; a value commonly larger than the predicted GIA signal magnitude. In the absence of reliable forward models of plate rotation or GIA then Antarctic geodetic velocities cannot totally and unambiguously constrain either process, especially GIA.

  8. Isostatic uplift, crustal attenuation, and the evolution of an extensional detachment system in southwestern Nevada

    SciTech Connect

    Scott, R.B.

    1987-12-31

    Geological and geophysical evidence supports the existence of extensional detachments, between the Sheep Range and Death Valley. It is proposed that geographically separated pieces of detachments between Death Valley and the Sheep Range are parts of a regional detachment system that has evolved since the Miocene, and that the system consists of lenses of strata separated by an anastomosing network of low- and high-angle normal faults. This manuscript emphasizes the probability that isostatic uplift within the region of greatest crustal attenuation in this system, the Bullfrog Hills core complex, controlled the evolution of the detachment system between the breakaway zone a the Sheep Range and the core complex. Features in this system are described from east to west, which is the apparent direction of tectonic transport.

  9. Volcanism, isostatic residual gravity and regional tectonic setting of the Cascade volcanic province

    USGS Publications Warehouse

    Blakely, R.J.; Jachens, R.C.

    1990-01-01

    A technique to locate automatically boundaries between crustal blocks of disparate densities was applied to upward continued isostatic residual gravity data. The boundary analysis delineates a narrow gravitational trough that extends the length of the Pliocene and Quaternary volcanic arc from Mount Baker in northern Washington to Lassen Peak in California. Gravitational highs interrupt the trough at two localities: a northwest trending high in southern Washington and a northeast trending high between Mount Shasta and Lassen Peak. The gravity sources may reflect upper crustal structures older than the High Cascades, possibly relicts from earlier accretionary events or more recent crustal deformation, that have actively influenced the spatial location of more recent volcanism. Much of the Pliocene and Quaternary volcanism of the Cascade arc has concentrated on or near contacts between crustal blocks of disparate density. These contacts may promote the ascension of magma to the Earth's surface. -from Authors

  10. Widespread low rates of Antarctic glacial isostatic adjustment revealed by GPS observations

    NASA Astrophysics Data System (ADS)

    Thomas, Ian D.; King, Matt A.; Bentley, Michael J.; Whitehouse, Pippa L.; Penna, Nigel T.; Williams, Simon D. P.; Riva, Riccardo E. M.; Lavallee, David A.; Clarke, Peter J.; King, Edward C.; Hindmarsh, Richard C. A.; Koivula, Hannu

    2011-11-01

    Bedrock uplift in Antarctica is dominated by a combination of glacial isostatic adjustment (GIA) and elastic response to contemporary mass change. Here, we present spatially extensive GPS observations of Antarctic bedrock uplift, using 52% more stations than previous studies, giving enhanced coverage, and with improved precision. We observe rapid elastic uplift in the northern Antarctic Peninsula. After considering elastic rebound, the GPS data suggests that modeled or empirical GIA uplift signals are often over-estimated, particularly the magnitudes of the signal maxima. Our observation that GIA uplift is misrepresented by modeling (weighted root-mean-squares of observation-model differences: 4.9-5.0 mm/yr) suggests that, apart from a few regions where large ice mass loss is occurring, the spatial pattern of secular ice mass change derived from Gravity Recovery and Climate Experiment (GRACE) data and GIA models may be unreliable, and that several recent secular Antarctic ice mass loss estimates are systematically biased, mainly too high.

  11. Hot isostatic atmospheric pressure casting H-K9L lightweight mirror

    NASA Astrophysics Data System (ADS)

    Ren, Jianfeng; Wang, Yi; Qiu, Gufeng; Ni, Yin; Huang, QiTai; Wang, Gang; Tang, Xiaojun

    2016-10-01

    Glass lightweight mirror can be made by Hot Isostatic Atmospheric Pressure (HIAP) casting method which melting small glass chunks into a mold that made lots of hexagon-shaped pockets in the back of the mirror. Alumina-silica refractory cores which used to form honeycomb mold can withstand over 950 degree Celsius temperature. Furnace temperature rises to 950 degree Celsius after H4 H-K9L chunks loaded into mold, holds this temperature over 2 hours and then drops to room temperature slowly. HIAP casting lightweight blank can used to form 1/60 λ RMS (λ=0.6328μm) mirror and this method can use to made big diameter lightweight blank.

  12. Modelling the Laurentide Ice Sheet using improved ice margin chronologies and glacio-isostatic observations

    NASA Astrophysics Data System (ADS)

    Gowan, Evan; Tregoning, Paul; Purcell, Anthony; Lambeck, Kurt

    2013-04-01

    Creating models of the Laurentide ice sheet is challenging, due to the deficiency of chronological constraints and the uneven spatial resolution of data to determine the evolution of the glacio-isostatic response after deglaciation. Previous models relied on uncalibrated radiocarbon constrained margins that proved to have deficiencies in recent studies. Additionally, many recent Laurentide ice sheet models have been developed by incorporating climatic parameters that are poorly resolved for the late glacial period. We present a new ice sheet model by an iterative process of changing basal shear stress values and ice sheet margin location. A particular focus of this study is to determine the thickness and extent of the western Laurentide ice sheet, where there were few well dated observations of glacio-isostatic motion until recently. The volume of an ice sheet during long periods depends mostly on basal shear stress and margin position, which are the main parameters that we vary to fit our model to glacio-isostatic observations. We build our ice model using the assumption of perfectly plastic, steady-state conditions, with variable basal shear stress. Basal shear stress values depend on the surficial geology underlying the ice, and are at a minimum in offshore regions that have soft, deformable sediments, and at a maximum in areas with exposed crystalline bedrock. This approach may not capture dynamic and short lived features of the ice sheet, such as ice streams and stagnant ice, but gives an approximation of average conditions to produce ice volumes that fit geophysical observations. We adjust the margin location when the shear stress conditions alone cannot account for the observed glacio-isostatic response. The constraints on the response include relative sea level benchmarks, sea level highstand positions and proglacial lakes. We repeat the analysis using different rheological profiles to determine the dependence the Earth model has on the estimation of ice

  13. Glacial isostatic adjustment using GNSS permanent stations and GIA modelling tools

    NASA Astrophysics Data System (ADS)

    Kollo, Karin; Spada, Giorgio; Vermeer, Martin

    2013-04-01

    Glacial Isostatic Adjustment (GIA) affects the Earth's mantle in areas which were once ice covered and the process is still ongoing. In this contribution we focus on GIA processes in Fennoscandian and North American uplift regions. In this contribution we use horizontal and vertical uplift rates from Global Navigation Satellite System (GNSS) permanent stations. For Fennoscandia the BIFROST dataset (Lidberg, 2010) and North America the dataset from Sella, 2007 were used respectively. We perform GIA modelling with the SELEN program (Spada and Stocchi, 2007) and we vary ice model parameters in space in order to find ice model which suits best with uplift values obtained from GNSS time series analysis. In the GIA modelling, the ice models ICE-5G (Peltier, 2004) and the ice model denoted as ANU05 ((Fleming and Lambeck, 2004) and references therein) were used. As reference, the velocity field from GNSS permanent station time series was used for both target areas. Firstly the sensitivity to the harmonic degree was tested in order to reduce the computation time. In the test, nominal viscosity values and pre-defined lithosphere thicknesses models were used, varying maximum harmonic degree values. Main criteria for choosing the suitable harmonic degree was chi-square fit - if the error measure does not differ more than 10%, then one might use as well lower harmonic degree value. From this test, maximum harmonic degree of 72 was chosen to perform calculations, as the larger value did not significantly modify the results obtained, as well the computational time for observations was kept reasonable. Secondly the GIA computations were performed to find the model, which could fit with highest probability to the GNSS-based velocity field in the target areas. In order to find best fitting Earth viscosity parameters, different viscosity profiles for the Earth models were tested and their impact on horizontal and vertical velocity rates from GIA modelling was studied. For every

  14. Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation

    USGS Publications Warehouse

    Praetorius, Summer; Mix, Alan; Jensen, Britta; Froese, Duane; Milne, Glenn A.; Wolhowe, Matthew; Addison, Jason A.; Prahl, Fred

    2016-01-01

    Observations of enhanced volcanic frequency during the last deglaciation have led to the hypothesis that ice unloading in glaciated volcanic terrains can promote volcanism through decompression melting in the shallow mantle or a reduction in crustal magma storage time. However, a direct link between regional climate change, isostatic adjustment, and the initiation of volcanism remains to be demonstrated due to the difficulty of obtaining high-resolution well-dated records that capture short-term climate and volcanic variability traced to a particular source region. Here we present an exceptionally resolved record of 19 tephra layers paired with foraminiferal oxygen isotopes and alkenone paleotemperatures from marine sediment cores along the Southeast Alaska margin spanning the last deglacial transition. Major element compositions of the tephras indicate a predominant source from the nearby Mt. Edgecumbe Volcanic Field (MEVF). We constrain the timing of this regional eruptive sequence to 14.6–13.1 ka. The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling–Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ18Osw) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.

  15. Preliminary isostatic gravity map of the Sonoma volcanic field and vicinity, Sonoma and Napa Counties, California

    USGS Publications Warehouse

    Langenheim, V.E.; Roberts, C.W.; McCabe, C.A.; McPhee, D.K.; Tilden, J.E.; Jachens, R.C.

    2006-01-01

    This isostatic residual gravity map is part of a three-dimensional mapping effort focused on the subsurface distribution of rocks of the Sonoma volcanic field in Napa and Sonoma counties, northern California. This map will serve as a basis for modeling the shapes of basins beneath the Santa Rosa Plain and Napa and Sonoma Valleys, and for determining the location and geometry of faults within the area. Local spatial variations in the Earth's gravity field (after accounting for variations caused by elevation, terrain, and deep crustal structure explained below) reflect the distribution of densities in the mid to upper crust. Densities often can be related to rock type, and abrupt spatial changes in density commonly mark lithologic boundaries. High-density basement rocks exposed within the northern San Francisco Bay area include those of the Mesozoic Franciscan Complex and Great Valley Sequence present in the mountainous areas of the quadrangle. Alluvial sediment and Tertiary sedimentary rocks are characterized by low densities. However, with increasing depth of burial and age, the densities of these rocks may become indistinguishable from those of basement rocks. Tertiary volcanic rocks are characterized by a wide range in densities, but, on average, are less dense than the Mesozoic basement rocks. Isostatic residual gravity values within the map area range from about -41 mGal over San Pablo Bay to about 11 mGal near Greeg Mountain 10 km east of St. Helena. Steep linear gravity gradients are coincident with the traces of several Quaternary strike-slip faults, most notably along the West Napa fault bounding the west side of Napa Valley, the projection of the Hayward fault in San Pablo Bay, the Maacama Fault, and the Rodgers Creek fault in the vicinity of Santa Rosa. These gradients result from juxtaposing dense basement rocks against thick Tertiary volcanic and sedimentary rocks.

  16. Heinrich events driven by feedback between ocean forcing and glacial isostatic adjustment

    NASA Astrophysics Data System (ADS)

    Bassis, J. N.; Petersen, S. V.; Cathles, L. M. M., IV

    2015-12-01

    One of the most puzzling glaciological features of the past ice age is the episodic discharge of large volumes of icebergs from the Laurentide Ice Sheet, known as Heinrich events. It has been suggested that Heinrich events are caused by internal instabilities in the ice sheet (e.g. the binge-purge oscillation). A purely ice dynamic cycle, however, is at odds with the fact that every Heinrich event occurs during the cold phase of a DO cycle, implying some regional climate connection. Recent work has pointed to subsurface water warming as a trigger for Heinrich events through increased basal melting of an ice shelf extending across the Hudson Strait and connecting with the Greenland Ice Sheet. Such a large ice shelf, spanning the deepest part of the Labrador Sea, has no modern analog and limited proxy evidence. Here we use a width averaged "flowline" model of the Hudson Strait ice stream to show that Heinrich events can be triggered by ocean forcing of a grounded terminus without the need for an ice shelf. At maximum ice extent, bed topography is depressed and the terminus is more sensitive to a subsurface thermal forcing. Once triggered, the retreat is rapid, and continues until isostatic rebound of the bed causes local sea level to drop sufficiently to arrest retreat. Topography slowly rebounds, decreasing the sensitivity to ocean forcing and the ice stream re-advances at a rate that is an order of magnitude slower than collapse. This simple feedback cycle between a short-lived ocean trigger and slower isostatic adjustment can reproduce the periodicity and timing of observed Heinrich events under a range of glaciological and solid earth parameters. Our results suggest that not only does the solid Earth play an important role in regulating ice sheet stability, but that grounded marine terminating portions of ice sheets may be more sensitive to ocean forcing than previously thought.

  17. Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation

    NASA Astrophysics Data System (ADS)

    Praetorius, Summer; Mix, Alan; Jensen, Britta; Froese, Duane; Milne, Glenn; Wolhowe, Matthew; Addison, Jason; Prahl, Fredrick

    2016-10-01

    Observations of enhanced volcanic frequency during the last deglaciation have led to the hypothesis that ice unloading in glaciated volcanic terrains can promote volcanism through decompression melting in the shallow mantle or a reduction in crustal magma storage time. However, a direct link between regional climate change, isostatic adjustment, and the initiation of volcanism remains to be demonstrated due to the difficulty of obtaining high-resolution well-dated records that capture short-term climate and volcanic variability traced to a particular source region. Here we present an exceptionally resolved record of 19 tephra layers paired with foraminiferal oxygen isotopes and alkenone paleotemperatures from marine sediment cores along the Southeast Alaska margin spanning the last deglacial transition. Major element compositions of the tephras indicate a predominant source from the nearby Mt. Edgecumbe Volcanic Field (MEVF). We constrain the timing of this regional eruptive sequence to 14.6-13.1 ka. The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling-Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ18Osw) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.

  18. An Ensemble Analysis of Antarctic Glacial Isostatic Adjustment and Sea Level

    NASA Astrophysics Data System (ADS)

    Lecavalier, B.; Tarasov, L.

    2016-12-01

    Inferences of past ice sheet evolution that lack any uncertainty assessment (implicit or explicit), have little value. A developing technique for explicit uncertainty quantification of glacial systems is Bayesian calibration of models against large observational data-sets (Tarasov et al., 2012). The foundation for a Bayesian calibration of a 3D glacial systems model (GSM) for Antarctica has recently been completed (Briggs et al., 2013; 2014; Briggs and Tarasov, 2013). Bayesian calibration thoroughly samples model uncertainties against fits to observational data to generate a probability distribution for the Antarctic Ice Sheet deglaciation with explicit and well-defined confidence intervals. To have validity as a complete inference of past ice sheet evolution, Bayesian calibration requires a model that "brackets reality".Past work has shown the GSM to have likely inadequate range of grounding line migration in certain sectors as well as persistent ice thickness biases in topographically complex regions (Briggs et al., 2014). To advance towards full calibration, these deficiencies are being addressed through a number of model developments. The grounding line scheme has been revised (Pollard and DeConto, 2012), the horizontal resolution is increased to 20 km, and boundary conditions are updated. The basal drag representation now includes the sub-grid treatment of the thermo-mechanical impacts of high basal roughness. Parametric uncertainties in basal drag for regions that are presently marine have been re-evaluated. The impact of past changes in ocean temperature on sub ice shelf melt is explicitly incorporated in the current ocean forcing parametric scheme. Uncertainties in earth rheology are also probed to robustly quantify uncertainties affiliated with glacial isostatic adjustment. The ensemble analysis of the Antarctic glacial system provides dynamical bounds on past and present Antarctica glacial isostatic adjustment and sea level contributions. This research

  19. Topographic/isostatic evaluation of new-generation GOCE gravity field models

    NASA Astrophysics Data System (ADS)

    Hirt, C.; Kuhn, M.; Featherstone, W. E.; GöTtl, F.

    2012-05-01

    We use gravity implied by the Earth's rock-equivalent topography (RET) and modeled isostatic compensation masses to evaluate the new global gravity field models (GGMs) from European Space Agency (ESA)'s Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite gravimetry mission. The topography is now reasonably well-known over most of the Earth's landmasses, and also where conventional GGM evaluation is prohibitive due to the lack (or unavailability) of ground-truth gravity data. We construct a spherical harmonic representation of Earth's RET to derive band-limited topography-implied gravity, and test the somewhat simplistic Airy/Heiskanen and Pratt/Hayford hypotheses of isostatic compensation, but which did not improve the agreement between gravity from the uncompensated RET and GOCE. The third-generation GOCE GGMs (based on 12 months of space gravimetry) resolve the Earth's gravity field effectively up to spherical harmonic degree ˜200-220 (˜90-100 km resolution). Such scales could not be resolved from satellites before GOCE. From the three different GOCE processing philosophies currently in use by ESA, the time-wise and direct approaches exhibit the highest sensitivity to short-scale gravity recovery, being better than the space-wise approach. Our topography-implied gravity comparisons bring evidence of improvements from GOCE to gravity field knowledge over the Himalayas, Africa, the Andes, Papua New Guinea and Antarctic regions. In attenuated form, GOCE captures topography-implied gravity signals up to degree ˜250 (˜80 km resolution), suggesting that other signals (originating, e.g., from the crust-mantle boundary and buried loads) are captured as well, which might now improve our knowledge on the Earth's lithosphere structure at previously unresolved spatial scales.

  20. 7 CFR 58.421 - Press.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... openings readily cleanable. The pressure device shall be the continuous type. Press cloths shall be maintained in good repair and in a sanitary condition. Single service press cloths shall be used only once....

  1. 7 CFR 58.421 - Press.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... openings readily cleanable. The pressure device shall be the continuous type. Press cloths shall be maintained in good repair and in a sanitary condition. Single service press cloths shall be used only once....

  2. 7 CFR 58.421 - Press.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... openings readily cleanable. The pressure device shall be the continuous type. Press cloths shall be maintained in good repair and in a sanitary condition. Single service press cloths shall be used only once....

  3. Insights into the Crustal Structure and Geodynamic Evolution of the Southern Granulite Terrain, India, from Isostatic Considerations

    NASA Astrophysics Data System (ADS)

    Kumar, Niraj; Singh, A. P.; Singh, B.

    2011-10-01

    The Southern Granulite Terrain of India, formed through an ancient continental collision and uplift of the earth's surface, was accompanied by thickening of the crust. Once the active tectonism ceased, the buoyancy of these deep crustal roots must have supported the Nilgiri and Palani-Cardamom hills. Here, the gravity field has been utilized to provide new constraints on how the force of buoyancy maintains the state of isostasy in the Southern Granulite Terrain. Isostatic calculations show that the seismically derived crustal thickness of 43-44 km in the Southern Granulite Terrain is on average 7-8 km more than that required to isostatically balance the present-day topography. This difference cannot be solely explained applying a constant shift in the mean sea level crustal thickness of 32 km. The isostatic analysis thus indicates that the current topography of the Southern Granulite Terrain is overcompensated, and about 1.0 km of the topographic load must have been eroded from this region without any isostatic readjustment. The observed gravity anomaly, an order of magnitude lower than that expected (-125 mGal), however, shows that there is no such overcompensation. Thermal perturbations up to Pan-African, present-day high mantle heat flow and low Te together negate the possible resistance of the lithosphere to rebound in response to erosional unloading. To isostatically compensate the crustal root, compatible to seismic Moho, a band of high density (2,930 kg m-3) in the lower crust and low density (3,210 kg m-3) in the lithospheric mantle below the Southern Granulite Terrain is needed. A relatively denser crust due to two distinct episodes of metamorphic phase transitions at 2.5 Ga and 550 Ma and highly mobilized upper mantle during Pan-African thermal perturbation reduced significantly the root buoyancy that kept the crust pulled downward in response to the eroded topography.

  4. Orion L-1 Press Conference

    NASA Image and Video Library

    2014-12-03

    In the Kennedy Space Center’s Press Site auditorium, agency and industry leaders spoke to members of the news media as the Orion spacecraft and its Delta IV Heavy rocket were being prepared for launch. From left are: Brandi Dean of NASA Public Affairs, Mark Geyer, Orion program manager, Mike Hawes, Lockheed Martin Orion Program manager, Jeff Angermeier, Exploration Flight Test-1 Ground Systems Development and Operations mission manager, Ron Fortson, United Launch Alliance director of mission management, and Kathy Winters, U.S. Air Force 45th Space Wing Launch Weather officer.

  5. Mars Science Laboratory Press Conference

    NASA Image and Video Library

    2011-07-22

    Michael Watkins (third from left), mission manager and project engineer, Mars Science Laboratory (MSL), Jet Propulsion Lab, Pasadena, Calif., speaks at a press conference at the Smithsonian's National Air and Space Museum on Friday, July 22, 2011 in Washington. From left to right, Watkins is joined by Dwayne Brown, NASA Headquarters public affairs officer; Michael Meyer, lead scientist Mars Exploration Program, NASA Headquarters; Watkins; John Grant, geologist, Smithsonian National Air and Space Museum in Washington; Dawn Sumner, geologist, University of California, Davis and John Grotzinger, MSL project scientist, JPL. Photo Credit: (NASA/Carla Cioffi)

  6. Mars Science Laboratory Press Conference

    NASA Image and Video Library

    2011-07-22

    John Grotzinger, Mars Science Laboratory (MSL) project scientist, Jet Propulsion Lab (JPL), Pasadena, Calif., answers a reporter's question at a press conference at the Smithsonian's National Air and Space Museum on Friday, July 22, 2011 in Washington. The MSL is scheduled to launch late this year from NASA's Kennedy Space Center in Florida and land in August 2012. Curiosity is twice as long and more than five times as heavy as previous Mars rovers. The rover will study whether the landing region at Gale crater had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed. Photo Credit: (NASA/Carla Cioffi)

  7. Mars Science Laboratory Press Conference

    NASA Image and Video Library

    2011-07-22

    John Grotzinger, Mars Science Laboratory (MSL) project scientist, Jet Propulsion Lab (JPL), Pasadena, Calif., holds up a model of the MSL, or Curiosity, at a press conference at the Smithsonian's National Air and Space Museum on Friday, July 22, 2011 in Washington. The MSL is scheduled to launch late this year from NASA's Kennedy Space Center in Florida and land in August 2012. Curiosity is twice as long and more than five times as heavy as previous Mars rovers. The rover will study whether the landing region at Gale crater had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed. Photo Credit: (NASA/Carla Cioffi)

  8. Antares Post Launch Press Conference

    NASA Image and Video Library

    2013-09-18

    Alan Lindenmoyer, program manager, NASA's Commercial Crew and Cargo Program, left, and, Frank Culbertson, executive vice president, Orbital Sciences Corporation,are seen during a press conference held after the successful launch of the Orbital Sciences Antares rocket, with the Cygnus cargo spacecraft aboard, Wednesday, Sept. 18, 2013, NASA Wallops Flight Facility, Virginia. Cygnus is on its way to rendezvous with the space station. The spacecraft will deliver about 1,300 pounds (589 kilograms) of cargo, including food and clothing, to the Expedition 37 crew. Photo Credit: (NASA/Bill Ingalls)

  9. Antares Post Launch Press Conference

    NASA Image and Video Library

    2013-09-18

    Josh Byerly, public affairs officer, NASA, left, Robert Lightfoot, associate administrator, NASA, second from left, Alan Lindenmoyer, program manager, NASA's Commercial Crew and Cargo Program, and, Frank Culbertson, executive vice president, Orbital Sciences Corporation, right, are seen during a press conference held after the successful launch of the Antares rocket, with the Cygnus cargo spacecraft aboard, Wednesday, Sept. 18, 2013, NASA Wallops Flight Facility, Virginia. Cygnus is on its way to rendezvous with the space station. The spacecraft will deliver about 1,300 pounds (589 kilograms) of cargo, including food and clothing, to the Expedition 37 crew. Photo Credit: (NASA/Bill Ingalls)

  10. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 Soyuz Commander Oleg Kotov, left, answers a reporter's question as Flight Engineer Soichi Noguchi of the Japan looks on during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  11. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 Flight Engineer Soichi Noguchi of Japan, right, and backup crew member Satoshi Furakawa wave farewell to reporters and family after a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  12. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 backup crew members, from left, NASA’s Doug Wheelock, Russian Anton Shkaplerov and Japan’s Satoshi Furakawa are seen during during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  13. Expedition 22 Prelaunch Press Conference

    NASA Image and Video Library

    2009-12-19

    Expedition 22 Soyuz Commander Oleg Kotov, right, answers a reporter's question as Flight Engineer Timothy J. Creamer looks on during a press conference held at the Cosmonaut Hotel in Baikonur, Kazakhstan, Saturday, Dec., 19, 2009. The launch of the Soyuz spacecraft with Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia and Flight Engineer Soichi Noguchi of Japan, is scheduled for Monday, Dec., 21, 2009 at 3:52a.m. Kazakhstan time. Photo Credit (NASA/Bill Ingalls)

  14. Mars Science Laboratory Press Conference

    NASA Image and Video Library

    2011-07-22

    John Grant, geologist, Smithsonian National Air and Space Museum in Washington, speaks at a Mars Science Laboratory (MSL) press conference at the Smithsonian's National Air and Space Museum on Friday, July 22, 2011 in Washington. The Mars Science Laboratory (MSL), or Curiosity, is scheduled to launch late this year from NASA's Kennedy Space Center in Florida and land in August 2012. Curiosity is twice as long and more than five times as heavy as previous Mars rovers. The rover will study whether the landing region at Gale crater had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed. Photo Credit: (NASA/Carla Cioffi)

  15. Mars Science Laboratory Press Conference

    NASA Image and Video Library

    2011-07-22

    NASA chief scientist, Dr. Waleed Abdalati, speaks at a Mars Science Laboratory (MSL) press conference at the Smithsonian's National Air and Space Museum on Friday, July 22, 2011 in Washington. The Mars Science Laboratory (MSL), or Curiosity, is scheduled to launch late this year from NASA's Kennedy Space Center in Florida and land in August 2012. Curiosity is twice as long and more than five times as heavy as previous Mars rovers. The rover will study whether the landing region at Gale crater had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed. Photo Credit: (NASA/Carla Cioffi)

  16. Mars Science Laboratory Press Conference

    NASA Image and Video Library

    2011-07-22

    Dawn Sumner, geologist, University of California, Davis speaks at a Mars Science Laboratory (MSL) press conference at the Smithsonian's National Air and Space Museum on Friday, July 22, 2011 in Washington. The Mars Science Laboratory (MSL), or Curiosity, is scheduled to launch late this year from NASA's Kennedy Space Center in Florida and land in August 2012. Curiosity is twice as long and more than five times as heavy as previous Mars rovers. The rover will study whether the landing region at Gale crater had favorable environmental conditions for supporting microbial life and for preserving clues about whether life ever existed. Photo Credit: (NASA/Carla Cioffi)

  17. Expedition 21 Prelaunch Press Conference

    NASA Image and Video Library

    2009-09-28

    Spaceflight Participant Guy Laliberté, left, Expedition 21 Flight Engineer Maxim Suraev, center, and Expedition 21 Flight Engineer Jeffrey N. Williams reveal t-shirts showing their faces superimposed on characters from the Russian movie "White Sun of the Desert" at the end of the press conference, Tuesday, Sept. 29, 2009 at the Cosmonaut Hotel in Baikonur, Kazakhstan. It is tradition for all crews flying on the Soyuz to watch this movie several days before they launch. Photo Credit: (NASA/Bill Ingalls)

  18. Yale University Press: Disseminating "Lux et Veritas"?

    ERIC Educational Resources Information Center

    Parrott, John B.

    2010-01-01

    America's university presses are situated within a network of over one hundred universities, learned societies, and scholarly associations. According to a pamphlet put out by the American Association of University Presses, these presses "make available to the broader public the full range and value of research generated by university faculty."…

  19. The Small Book Press: A Cultural Essential.

    ERIC Educational Resources Information Center

    Henderson, Bill

    1984-01-01

    Discussion of small literary book publishers notes works of small-press authors (Thomas Paine, Washington Irving, Walt Whitman, Mark Twain, Upton Sinclair, Anais Nin); today's outstanding presses (Creative Arts Book Company, Persea Books, Full Court Press, Reed and Cannon Company, Tuumba Books); and role of little magazines. Thirty-seven…

  20. 7 CFR 58.421 - Press.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Press. 58.421 Section 58.421 Agriculture Regulations... Plants Approved for USDA Inspection and Grading Service 1 Equipment and Utensils § 58.421 Press. The cheese press should be constructed of stainless steel and all joints welded and all surfaces, seams...