Sample records for floor slab assembly

  1. 16. 'Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, ...

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

    16. 'Concrete Bridge Over Salt River, Port Kenyon, Humboldt County, California, A.J. Logan, County Surveyor, H.J. Brunnier, Consulting Engineer, March 7, 1919,' showing detail of floor beam at central pier, half section of cantilever slab at end of bridge, floor beam end panels, slab reinforcing, plan of slab reinforcing, diagram of slab bars, typical floor girder. - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA

  2. 18. FOURTH FLOOR BLDG. 28, RAISED CONCRETE SLAB FLOOR WITH ...

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

    18. FOURTH FLOOR BLDG. 28, RAISED CONCRETE SLAB FLOOR WITH BLOCKS AND PULLEYS OVERHEAD LOOKING NORTHEAST. - Fafnir Bearing Plant, Bounded on North side by Myrtle Street, on South side by Orange Street, on East side by Booth Street & on West side by Grove Street, New Britain, Hartford County, CT

  3. Falls from height during the floor slab formwork of buildings: current situation in Spain.

    PubMed

    Adam, Jose M; Pallarés, Francisco J; Calderón, Pedro A

    2009-01-01

    One of the phases with the highest risk of falls from a height in the construction of a building is during the floor slab formwork stage. This paper analyzes this particular risk, as well as the most frequently used fall-protection systems. A survey was carried out to define the current situation in Spain with regard to falls from a height during floor slab formwork and the fall-protection systems used to prevent such a risk. The results of the survey clarified the current situation in Spain with regard to this risk, and made it clear that there is considerable risk of falling from a height during the floor slab formwork stage. All the safety systems analyzed presented a series of weak points that should be studied in detail before they can be used on building sites. The risk of falling associated with floor slab formwork and the most frequently used protection systems are analyzed. As no research had been carried out to date on this type of risk, we consider the research presented in this article to be a pioneer in the field.

  4. Floor foundations: preferences of architects and builders in six Southwestern United States markets

    Treesearch

    George B. Harpole; H. Edward Dickerhoof

    1971-01-01

    Mail questionnaires and follow-up interviews were used to determine preferences among three types of floor foundations: concrete slab, wood crawl-space, and a new design that combines a low-profile wood floor with underfloor plenum. Crawl-space construction was preferred in the Sacramento and Oakland-Martinez markets; concrete slab was preferred in the Los Angeles, San...

  5. Engineering and Design: Indoor Radon Prevention and Mitigation

    DTIC Science & Technology

    1993-09-15

    slabs on grade, capillary water barrier below floor slabs on grade, dampproofing or waterproofing and protection board on below grade walls, sealants in...will be lapped 12 inches and sealed with adhesives or pressure sensitive tape and sealed at foundation walls with mastic. Capillary water barrier will...Systems, Letter Codes B, C, and D. Sub- slab suction systems consist of 4 inch diameter perforated PVC pipe laid in the capillary water barrier below floor

  6. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Heat transfer to slab foundations has remained an area of building science with poor understanding over the last three decades of energy efficiency research. This is somewhat surprising since the area of floors in single family homes is generally equal to wall, or windows or attics which have been extensively evaluated. Research that has been done has focused in the impact of slab on grade foundations and insulation schemes on heat losses associated with heating in predominantly heating dominated climates. Slab on grade construction is very popular in cooling-dominated southern states where it accounts for 77 percent of new homemore » floors according to U.S. Census data in 2014. There is a widespread conception that tile flooring, as opposed to carpet, makes for a cooler home interior in warm climates. Empirical research is needed as building energy simulations such as DOE-2 and EnergyPlus rely on simplified models to evaluate these influences. BA-PIRC performed experiments over an entire year from 2014-2015 in FSEC's Flexible Residential Test Facilities (FRTF) intended to assess for the first time 1) slab on grade influence in a cooling dominated climate, and 2) how the difference in a carpeted vs. uncarpeted building might influence heating and cooling. Two identical side by side residential buildings were evaluated, the East with pad and carpet and the west with a bare slab floor. A highly detailed grid of temperature measurements were taken on the slab surface at various locations as well as at depths of 1, 2.5, 5, 10 and 20 feet.« less

  7. Evaluation of the Impact of Slab Foundation Heat Transfer on Heating and Cooling in Florida

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Parker, D.; Kono, J.; Vieira, R.

    During the last three decades of energy-efficiency research, there has been limited study of heat transfer to slab-on-grade foundations in cooling-dominated climates. Most experimental research has focused on the impact of slab-on-grade foundations and insulation schemes on heat losses in heating-dominated climates. This is surprising because the floor area in single-family homes is generally equal to wall area, window area, or attic area, all of which have been extensively evaluated for heat-transfer properties. Moreover, slab foundations are the most common foundation type in cooling-dominated climates. Slab-on-grade construction is very popular in southern states, accounting for 77% of new home floorsmore » according to 2014 U.S. Census data. There is a widespread perception that tile flooring, as opposed to carpet, provides a cooler home interior in warm climates. Empirical research is needed because building energy simulation software programs running DOE-2 and EnergyPlus engines often rely on simplified models to evaluate the influence of flooring on interior temperature, even though in some cases more detailed models exist. The U.S. Department of Energy Building America Partnership for Improved Residential Construction (BA-PIRC) performed experiments in the Florida Solar Energy Center’s Flexible Residential Test Facility intended to assess for the first time (1) how slab-on-grade construction influences interior cooling in a cooling-dominated climate and (2) how the difference in a carpeted versus uncarpeted building might influence heating and cooling energy use. Two nominally identical side-by-side residential buildings were evaluated during the course of 1 year, from 2014 to 2015: the east building with a pad and carpet floor and the west building with a bare slab floor. A detailed grid shows temperature measurements taken on the slab surface at various locations as well as at depths of 1.0 ft, 2 ft, 5.0 ft, 10.0 ft, and 20.0 ft below the surface. Temperature measurements were taken at both buildings for more than 3 years prior to the experiments to ensure that the ground and foundation temperatures had fully come into equilibrium.« less

  8. Building America Case Study: Impact of Slab-Foundation Heat Transfer on Space-Conditioning Energy Use in Florida, Cocoa, Florida

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    D. Parker, E. Martin

    Heat transfer to slab foundations has remained an area of building science with poor understanding over the last three decades of energy efficiency research. This is somewhat surprising since the area of floors in single family homes is generally equal to wall, or windows or attics which have been extensively evaluated. Research that has been done has focused in the impact of slab on grade foundations and insulation schemes on heat losses associated with heating in predominantly heating dominated climates. Slab on grade construction is very popular in cooling-dominated southern states where it accounts for 77 percent of new homemore » floors according to U.S. Census data in 2014. There is a widespread conception that tile flooring, as opposed to carpet, makes for a cooler home interior in warm climates. Empirical research is needed as building energy simulations such as DOE-2 and EnergyPlus rely on simplified models to evaluate these influences. BA-PIRC performed experiments over an entire year from 2014-2015 in FSEC's Flexible Residential Test Facilities (FRTF) intended to assess for the first time 1) slab on grade influence in a cooling dominated climate, and 2) how the difference in a carpeted vs. uncarpeted building might influence heating and cooling. Two identical side by side residential buildings were evaluated, the East with pad and carpet and the west with a bare slab floor. A highly detailed grid of temperature measurements were taken on the slab surface at various locations as well as at depths of 1, 2.5, 5, 10 and 20 feet.« less

  9. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Parker, D.; Kono, J.; Vieira, R.

    During the last three decades of energy-efficiency research, there has been limited study of heat transfer to slab-on-grade foundations in cooling-dominated climates. Most experimental research has focused on the impact of slab-on-grade foundations and insulation schemes on heat losses in heating-dominated climates. This is surprising because the floor area in single-family homes is generally equal to wall area, window area, or attic area, all of which have been extensively evaluated for heat-transfer properties. Moreover, slab foundations are the most common foundation type in cooling-dominated climates. Slab-on-grade construction is very popular in southern states, accounting for 77% of new home floorsmore » according to 2014 U.S. Census data. There is a widespread perception that tile flooring, as opposed to carpet, provides a cooler home interior in warm climates. Empirical research is needed because building energy simulation software programs running DOE-2 and EnergyPlus engines often rely on simplified models to evaluate the influence of flooring on interior temperature, even though in some cases more detailed models exist. The U.S. Department of Energy Building America Partnership for Improved Residential Construction (BA-PIRC) performed experiments in the Florida Solar Energy Center’s Flexible Residential Test Facility intended to assess for the first time (1) how slab-on-grade construction influences interior cooling in a cooling-dominated climate and (2) how the difference in a carpeted versus uncarpeted building might influence heating and cooling energy use. Two nominally identical side-by-side residential buildings were evaluated during the course of 1 year, from 2014 to 2015: the east building with a pad and carpet floor and the west building with a bare slab floor. A detailed grid shows temperature measurements taken on the slab surface at various locations as well as at depths of 1.0 ft, 2 ft, 5.0 ft, 10.0 ft, and 20.0 ft below the surface. Temperature measurements were taken at both buildings for more than 3 years prior to the experiments to ensure that the ground and foundation temperatures had fully come into equilibrium.« less

  10. Analysis of Slab-column Shearwall Structure of 6000 Tons Cold Storage

    NASA Astrophysics Data System (ADS)

    He, Dongqing; Song, Pengwei; Jie, Pengyu

    2018-05-01

    Combining with the functional requirements, the site conditions and the 6000 tons load characteristics of cold storage, so determine its structure system for the slab-column-shear wall structure. The paper recommends the design of foundation, the settings of column cap, the arrangement of shear wall, the punching shear of floor slab and the analysis and calculation results of main structure. By addition shear wall in slab-column structure to increase the overall stiffness of structure and improve the seismic performance of structure. Take the detached form between the main structure and the external wall insulation, while set anchorage beam between in the main floor and the ring beam along the axis of the column grid to enhance the overall stability of the external wall insulation.

  11. Structural Element Tests in Support of the Keyworker Blast Shelter Program

    DTIC Science & Technology

    1985-10-01

    forced concrete -lab with two transverse reinforced concrete floor beams to transfer the interior column loads to the floor slab. Using a roof slab... lateral buck- "-4 ling; however, this could have occurred after a column buckled and the roof collapsed. Since load cell 2 (middle column ) recorded the...ANALYSIS OF FREE-FIELD AND STRUCTURE LOADING DATA ... ........ .. 102 6.1.1 Loading Wave Velocity ........... .................... ... 102 6.1.2 Lateral

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

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

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

  13. Discussion on the installation checking method of precast composite floor slab with lattice girders

    NASA Astrophysics Data System (ADS)

    Chen, Li; Jin, Xing; Wang, Yahui; Zhou, Hele; Gu, Jianing

    2018-03-01

    Based on the installation checking requirements of China’s current standards and the international norms for prefabricated structural precast components, it proposed an installation checking method for precast composite floor slab with lattice girders. By taking an equivalent composite beam consisted of a single lattice girder and the precast concrete slab as the checking object, compression instability stress of upper chords and yield stress of slab distribution reinforcement at the maximum positive moment, tensile yield stress of upper chords, slab normal section normal compression stress and shear instability stress of diagonal bars at the maximum negative moment were checked. And the bending stress and deflection of support beams, strength and compression stability bearing capacity of the vertical support, shear bearing capacity of the bolt and compression bearing capacity of steel tube wall at the bolt were checked at the same time. Every different checking object was given a specific load value and load combination. Application of installation checking method was given and testified by example.

  14. Stress-strain state of the structure in the service area of underground railway

    NASA Astrophysics Data System (ADS)

    Barabash, M.; Bashinsky, Y.; Korjakins, A.

    2017-10-01

    The paper focuses on numerical study how vibration due to underground trains influences the load-bearing building structures. Diagrams of vibration levels for monolithic floor slab depending on frequency are obtained. Levels of vibrations on floor slabs and columns are measured. The simulation of dynamic load from underground railway onto load-bearing building structures is presented as an example with account of load transmission through the soil. Recommendations for generation of design model in dynamic analysis of structure are provided.

  15. Numerical Analysis of Prefabricated Steel-Concrete Composite Floor in Typical Lipsk Building

    NASA Astrophysics Data System (ADS)

    Lacki, Piotr; Kasza, Przemysław; Derlatka, Anna

    2017-12-01

    The aim of the work was to perform numerical analysis of a steel-concrete composite floor located in a LIPSK type building. A numerical model of the analytically designed floor was performed. The floor was in a six-storey, retail and service building. The thickness of a prefabricated slab was 100 mm. The two-row, crisscrossed reinforcement of the slab was made from φ16 mm rods with a spacing of 150 x 200 mm. The span of the beams made of steel IPE 160 profiles was 6.00 m and they were spaced every 1.20 m. The steelconcrete composite was obtained using 80×16 Nelson fasteners. The numerical analysis was carried out using the ADINA System based on the Finite Element Method. The stresses and strains in the steel and concrete elements, the distribution of the forces in the reinforcement bars and cracking in concrete were evaluated. The FEM model was made from 3D-solid finite elements (IPE profile and concrete slab) and truss elements (reinforcement bars). The adopted steel material model takes into consideration the plastic state, while the adopted concrete material model takes into account material cracks.

  16. Floor foundations: preferences of new home buyers in six Southwestern United States markets

    Treesearch

    George B. Harpole; H. Edward Dickerhoof

    1971-01-01

    Mail questionnaires and follow-up interviews were used to determine preferences among three types of floor foundations: concrete slab, wood crawl-space, and a new design that combines a low-profile wood floor with underfloor plenum. More respondents from northern markets preferred the crawl-space floor than from the southern markets. Factors most often cited as...

  17. Research on Vibration Test in Urban Indoor Substation

    NASA Astrophysics Data System (ADS)

    Ma, Yuchao; Mo, Juan; Xu, Jin; Fan, Baozhen

    2018-01-01

    The problem of vibration and noise of urban indoor substations has becoming more and more socially concerned.The urban indoor substation of 110kV and its conjoined buildings were taken as the research object and the vibration tests of the transformer and each floor slab were respectively carried out.The sound vibration characteristics and sound transmission rules of the urban indoor substation were obtained through the time-frequency analysis and coherence analysis of the test data. The vibration spectrum of transformer body was mainly 100Hz together with its multiplying factors and the vibration characteristics of the floor slab were basically the same as those of the transformer body. it is crucial to control the vibration and noise transmission in the equipment floor of the urban indoor substation.

  18. Deterioration of the Floor of Interior Courtyard of Sultan Hassan Mosque in Cairo, Egypt.

    NASA Astrophysics Data System (ADS)

    Nazel, Tarek

    The college- mosque of Sultan Hassan is considered one of the finest examples of Islamic architecture not only in Egypt but also in the East. Its open interior courtyard is paved with three different types of marble slabs. These marble slabs suffer from severe deterioration. Causes of this deterioration were determined accurately through the ocular examination of the courtyard and confirmed by the laboratory tests which were carried out on samples representing the three common types of marble used in the floor namely the white, the red and the black marble. Sun light and heat are the main deterioration factors and the consequent thermal expansion is the main property which led to the detected deterioration phenomena. Types and mechanisms of deterioration affected the floor were described and explained.

  19. HOT CELL BUILDING, TRA632. FIRST FLOOR FOUNDATION PLAN SHOWS SECTIONALIZED ...

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

    HOT CELL BUILDING, TRA-632. FIRST FLOOR FOUNDATION PLAN SHOWS SECTIONALIZED FLOOR LOADINGS AND CONCRETE SLAB THICKNESSES, A TYPICAL FEATURE OF NUCLEAR ARCHITECTURE. IDAHO OPERATIONS OFFICE MTR-632-IDO-2, 11/1952. INL INDEX NO. 531-0632-62-396-110561, REV. 1. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  20. Experiment on the concrete slab for floor vibration evaluation of deteriorated building

    NASA Astrophysics Data System (ADS)

    Hong, S. U.; Na, J. H.; Kim, S. H.; Lee, Y. T.

    2014-08-01

    Damages from noise and vibration are increasing every year, and most of which are noises between floors in deteriorated building caused by floor impact sound. In this study, the floor vibration of the deteriorated buildings constructed with the concrete slabs of thickness no more than 150 mm was evaluated by the vibration impact sound. This highly reliable study was conducted to assess floor vibration according with the serviceability evaluation standard of Reiher / Meister and Koch and vibration evaluation standard of ISO and AIJ. Designed pressure for the concrete slab sample of floor vibration assessment was 24MPa, and the sample was manufactured pursuant to KS F 2865 and JIS A 1440-2 with size of 3200 mm × 3200 mm × 140 mm. Tests were conducted twice with accelerometers, and Fast Fourier Transform was performed for comparative analysis by the vibration assessment criteria. The peak displacement from Test 1 was in the range of 0.00869 - 0.02540 mm; the value of peak frequency ranged from 18 to 27 Hz, and the average value was 22Hz. The peak acceleration value from Test 2 was in the range of 0.47 - 1.07 % g; the value of peak frequency was 18.5 - 22.57 Hz, and the average was 21Hz. The vibration was apparently recognizable in most cases according to the Reiher/Meister standard. In case of Koch graph for the damage assessment of the structure, the vibration was at the medium level and causes no damage to the building structure. The measured vibration results did not exceed the damage limit or serviceability limit of building according to the vibration assessment criteria of ISO and residential assessment guidelines provided by Architectural Institute of Japan (AIJ).

  1. Strength and Stiffness Analysis by the Finite-Difference Method of a Concrete Floor Slab Reinforced with Composite Rods During a Fire

    NASA Astrophysics Data System (ADS)

    Shirko, A. V.; Kamlyuk, A. N.; Drobysh, A. S.; Spiglazov, A. V.

    2017-05-01

    A strength and stiffness comparative analysis has been made of a concrete slab reinforced with composite-reinforcement rods and a slab reinforced with steel rods. The stress-strain state has been assessed for both versions of reinforcement of the slab. The stress-strain state was determined under the action of only static load and with subsequent application of temperature fields, i.e., under standard-fire conditions. It has been shown that the fire resistance of the slab with a composite reinforcement turns out to be 1.6 higher as far as the bearing capacity is concerned, than the fire resistance of the slab with a steel reinforcement, although the initial deflection due to the action of only static load for the slab reinforced with composite rods exceeds six to seven times the deflection of the slab reinforced with steel rods.

  2. Light-assisted templated self assembly using photonic crystal slabs.

    PubMed

    Mejia, Camilo A; Dutt, Avik; Povinelli, Michelle L

    2011-06-06

    We explore a technique which we term light-assisted templated self-assembly. We calculate the optical forces on colloidal particles over a photonic crystal slab. We show that exciting a guided resonance mode of the slab yields a resonantly-enhanced, attractive optical force. We calculate the lateral optical forces above the slab and predict that stably trapped periodic patterns of particles are dependent on wavelength and polarization. Tuning the wavelength or polarization of the light source may thus allow the formation and reconfiguration of patterns. We expect that this technique may be used to design all-optically reconfigurable photonic devices.

  3. PROCESS WATER BUILDING, TRA605. FLOOR AND ROOF PLANS FOR SECOND ...

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

    PROCESS WATER BUILDING, TRA-605. FLOOR AND ROOF PLANS FOR SECOND FLOOR. DETAILS OF CONCRETE ROOF SLABS. FLASH EVAPORATOR SUPPORTS AND PIPE OPENINGS TO TANKS BELOW. NOTE SPECIFIES THAT EQUIPMENT IS TO BE INSTALLED BEFORE ERECTION OF ROOF AND WALLS. BLAW-KNOX 3150-805-4, 1/1951. INL INDEX NO. 531-0605-62-098-100660, REV. 2. - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  4. Light-assisted, templated self-assembly using a photonic-crystal slab.

    PubMed

    Jaquay, Eric; Martínez, Luis Javier; Mejia, Camilo A; Povinelli, Michelle L

    2013-05-08

    We experimentally demonstrate the technique of light-assisted, templated self-assembly (LATS). We excite a guided-resonance mode of a photonic-crystal slab with 1.55 μm laser light to create an array of optical traps. We demonstrate assembly of a square lattice of 520 nm diameter polystyrene particles spaced by 860 nm. Our results demonstrate how LATS can be used to fabricate reconfigurable structures with symmetries different from traditional colloidal self-assembly, which is limited by free energetic constraints.

  5. 13. The south segment of the building has a stone ...

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

    13. The south segment of the building has a stone basement. The alley wall had a number of areaway windows that are now infilled with bricks. These areaways were subsequently filled with earth, probably when the alley was paved. Here the first-floor joists are seen with a make-shift support beam and column. The basement floor originally was part earth and part wood. Some of the earth floor is now covered with a concrete slab; the wood floor remains. Credit GADA/MRM. - Stroud Building, 31-33 North Central Avenue, Phoenix, Maricopa County, AZ

  6. A dual-rating method for evaluating impact noise isolation of floor-ceiling assemblies.

    PubMed

    LoVerde, John J; Dong, D Wayland

    2017-01-01

    Impact Insulation Class (IIC), the single-number rating for evaluating the impact noise insulation of a floor-ceiling assembly, and the associated field testing ratings, are unsatisfactory because they do not have strong correlation with subjective reaction nor provide suitable detailed information for evaluation or design of floor-ceiling assemblies. Various proposals have been made for improving the method, but the data presented indicate that no single-number rating can adequately characterize the impact noise isolation of an assembly. For realistic impact noise sources and floor-ceiling assembly types, there are two frequency domains for impact noise, and the impact noise levels in the two domains can vary independently. Therefore, two ratings are required in order to satisfactorily evaluate the impact isolation provided by a floor-ceiling assembly. Two different ratings are introduced for measuring field impact isolation in the two frequency domains, using the existing impact source and measurement method. They are named low-frequency impact rating (LIR) and high-frequency impact rating (HIR). LIR and HIR are proposed to improve the current method for design and evaluation of floor-ceiling assemblies and also provide a better method for predicting subjective reaction.

  7. DOE ZERH Case Study: TC Legend Homes, Bellingham Power House, Bellingham, WA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    none,

    Case study of a DOE 2015 Housing Innovation Award winning custom home in the marine climate that got HERS 34 without PV or HERS -12 with PV, with 6” SIP walls and 10” SIP roof; R-28 ICF around slab, R-20 rigid foam under slab; radiant floor heat and passive design; air-to-water heat pump COP 4.4; HRV; earth tube ventilation; triple-pane windows, 100% LED.

  8. 61. photographer unknown undated FIRST CONCRETE BEING POURED IN DRAFT ...

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

    61. photographer unknown undated FIRST CONCRETE BEING POURED IN DRAFT TUBE FLOOR SLAB. - Bonneville Project, Powerhouse No.1, Spanning Bradford Slough, from Bradford Island, Bonneville, Multnomah County, OR

  9. Light-assisted, templated self-assembly of gold nanoparticle chains.

    PubMed

    Jaquay, Eric; Martínez, Luis Javier; Huang, Ningfeng; Mejia, Camilo A; Sarkar, Debarghya; Povinelli, Michelle L

    2014-09-10

    We experimentally demonstrate the technique of light-assisted, templated self-assembly (LATS) to trap and assemble 200 nm diameter gold nanoparticles. We excite a guided-resonance mode of a photonic-crystal slab with 1.55 μm laser light to create an array of optical traps. Unlike our previous demonstration of LATS with polystyrene particles, we find that the interparticle interactions play a significant role in the resulting particle patterns. Despite a two-dimensionally periodic intensity profile in the slab, the particles form one-dimensional chains whose orientations can be controlled by the incident polarization of the light. The formation of chains can be understood in terms of a competition between the gradient force due to the excitation of the mode in the slab and optical binding between particles.

  10. 20 CFR 654.409 - Heating.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... temperature in such quarters falls below 68°. (b) Any stoves or other sources of heat utilizing combustible... concrete slab, insulated metal sheet, or other fireproof material on the floor under each stove, extending...

  11. 20 CFR 654.409 - Heating.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... temperature in such quarters falls below 68°. (b) Any stoves or other sources of heat utilizing combustible... concrete slab, insulated metal sheet, or other fireproof material on the floor under each stove, extending...

  12. 20 CFR 654.409 - Heating.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... temperature in such quarters falls below 68°. (b) Any stoves or other sources of heat utilizing combustible... concrete slab, insulated metal sheet, or other fireproof material on the floor under each stove, extending...

  13. 20 CFR 654.409 - Heating.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... temperature in such quarters falls below 68°. (b) Any stoves or other sources of heat utilizing combustible... concrete slab, insulated metal sheet, or other fireproof material on the floor under each stove, extending...

  14. 20 CFR 654.409 - Heating.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... temperature in such quarters falls below 68°. (b) Any stoves or other sources of heat utilizing combustible... concrete slab, insulated metal sheet, or other fireproof material on the floor under each stove, extending...

  15. 60. photographer unknown undated CONCRETE BEING POURED ON CENTER PORTION ...

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

    60. photographer unknown undated CONCRETE BEING POURED ON CENTER PORTION OF DRAFT TUBE FLOOR SLAB. - Bonneville Project, Powerhouse No.1, Spanning Bradford Slough, from Bradford Island, Bonneville, Multnomah County, OR

  16. DOE Office of Scientific and Technical Information (OSTI.GOV)

    none,

    Tom Walsh & Company’s homes in an urban infill project in Portland achieved meets 2012 IECC insulation requirements in the marine climate with R-21 fiberglass batt walls, R-25 slab insulation and R-49 spray foam and cellulose attic floors.

  17. 5. ROOF DETAIL, LOOKING EAST TOWARD SECOND FLOOR WAREHOUSE FROM ...

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

    5. ROOF DETAIL, LOOKING EAST TOWARD SECOND FLOOR WAREHOUSE FROM ROOF OF ASSEMBLY AREA. - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  18. 6. PERSPECTIVE VIEW TO SOUTHWEST SHOWING NORTHWEST CORNER OF ASSEMBLY ...

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

    6. PERSPECTIVE VIEW TO SOUTHWEST SHOWING NORTHWEST CORNER OF ASSEMBLY BUILDING WHERE SHOWROOMS (FIRST FLOOR) AND OFFICES (SECOND FLOOR) WERE LOCATED. WEST SIDE OF ASSEMBLY AREA IS TO RIGHT. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  19. Upgrading Basements for Combined Nuclear Weapons Effects: Expedient Options

    DTIC Science & Technology

    1976-05-01

    reinforced concrete stairwell walls can be expected to be substantial in these cases, since they are supporting an axial load from higher floors. F...desirability) include: a. Stacked concrete block or brick b. Stacked timber * The latter situation is likely to occur only in load - bearing wall...concrete flat slab 4 Reinforced concrete flat plate 4 Load - bearing wall 3 The analysis of the floor systems for the 34 NSS buildings required the dynamic

  20. DOE ZERH Case Study: Clifton View Homes, Marine Drive and Port Hadlcok, Coupeville and Port Hadlock WA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    none,

    2015-09-01

    Case study of two DOE 2015 Housing Innovation Award winning custom homes in the marine climate that got HERS 39 and 38 without PV or HERS 2-12 and -9 with PV, with 6.5” SIP walls and 10.25” SIP roof; 11.75 ICF around slab, R-20 rigid foam under slab; radiant floor heat and passive design; air-to-water heatpump, fresh air intake with fan, triple-pane windows, 100% LED.

  1. DOE Office of Scientific and Technical Information (OSTI.GOV)

    none,

    This case study describes a DOE Zero Energy Ready Home in Seattle, WA, that scored HERS 42 without PV and a -1 with PV. This 3,192 ft2 custom home has 6-inch SIP walls, a 12-inch SIP roof, an R-28 ICF-insulated foundation slab edge with R-20 rigid foam under the slab; an air-to-water heat pump plus radiant floor heat; 100% LED lighting; filtered-fan-powered fresh air intake; triple-pane windows, 9.7 kWh PV for electric car charging station.

  2. Foundation Design against Frost Action in Europe.

    DTIC Science & Technology

    1988-03-01

    the inside of the foundation wall and consisted of 50mm of ’Rockwool’ (a mineral wool ). This insulation guides heat from the house down toward the...Separation of the floor slab from the inner part of the foundation wall by introducing mineral wool (Fig. 49c) gives a further slight reduction in...construction consisting, for example, of wood and mineral wool and including air spaces. Rt is the thermal resistance of the composite floor from surface to

  3. Developing short-span alternatives to reinforced concrete box culvert structures in Kansas.

    DOT National Transportation Integrated Search

    2014-07-01

    Concrete box culvert floor slabs are known to have detrimental effects on river and stream hydraulics. : Consequences include an aquatic environment less friendly to the passage of fish and other organisms. This has : prompted environmental regulatio...

  4. 8. VIEW TO EAST SHOWING PORTION OF WEST ELEVATION OF ...

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

    8. VIEW TO EAST SHOWING PORTION OF WEST ELEVATION OF ASSEMBLY AREA. MAIN ASSEMBLY LINE RAN FROM RIGHT TO LEFT ALONG THE FIRST-FLOOR WINDOWS. PARTS STORAGE WAS ON SECOND FLOOR. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  5. Systematic variation in the depths of slabs beneath arc volcanoes

    USGS Publications Warehouse

    England, P.; Engdahl, R.; Thatcher, W.

    2004-01-01

    The depths to the tops of the zones of intermediate-depth seismicity beneath arc volcanoes are determined using the hypocentral locations of Engdahl et al. These depths are constant, to within a few kilometres, within individual arc segments, but differ by tens of kilometres from one arc segment to another. The range in depths is from 65 km to 130 km, inconsistent with the common belief that the volcanoes directly overlie the places where the slabs reach a critical depth that is roughly constant for all arcs. The depth to the top of the intermediate-depth seismicity beneath volcanoes correlates neither with age of the descending ocean floor nor with the thermal parameter of the slab. This depth does, however, exhibit an inverse correlation with the descent speed of the subducting plate, which is the controlling factor both for the thermal structure of the wedge of mantle above the slab and for the temperature at the top of the slab. We interpret this result as indicating that the location of arc volcanoes is controlled by a process that depends critically upon the temperature at the top of the slab, or in the wedge of mantle, immediately below the volcanic arc.

  6. Developing short-span alternatives to reinforced concrete box culvert structures in Kansas : [technical summary].

    DOT National Transportation Integrated Search

    2014-07-01

    Concrete box culvert floor slabs are known to have detrimental effects on river and stream hydraulics. Consequences include an aquatic environment less friendly to the passage of fish and other organisms. This has prompted environmental regulations r...

  7. RAETRAD VERSION 3.1 USER MANUAL

    EPA Science Inventory

    This report is a user's manual for the RAETRAD (RAdon Emanation and TRAnsport into Dwellings) computer code. RAETRAD is a two-dimensional numerical model to simulate radon (Rn) entry and accumulation in houses from its calculated generation in soils, floor slabs, and footings an...

  8. School Tucked in an Envelope.

    ERIC Educational Resources Information Center

    AIA Journal, 1981

    1981-01-01

    At the Telluride (Colorado) school, the classroom wing was outfitted with a thick floor slab and a greenhouse space where heat is stored in waterfilled tubes. The gymnasium's southwestern wall was transformed into a Trombe wall by applying 2,000 square feet of glazing. (Author/MLF)

  9. 73. SECOND FLOOR, HEATER ROOM, BAY 31/5 SOUTH, WITH FANFORCED ...

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

    73. SECOND FLOOR, HEATER ROOM, BAY 31/5 SOUTH, WITH FAN-FORCED HOT AIR HEATER; TO SOUTHEAST - Ford Motor Company Edgewater Assembly Plant, Assembly Building, 309 River Road, Edgewater, Bergen County, NJ

  10. 7 CFR 1436.6 - Eligible storage or handling equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... eligible facility loan commodity, such as cleaners, moisture testers, and heat detectors; (4) Electrical... moisture testers, and heat detectors; (vii) Electrical equipment, including labor and materials for..., but are not limited to, the following: An insulated cement slab floor, insulation for walls and...

  11. 7 CFR 1436.6 - Eligible storage or handling equipment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... stored eligible facility loan commodity, such as cleaners, moisture testers, and heat detectors; (4... moisture testers, and heat detectors; (vii) Electrical equipment, including labor and materials for..., but are not limited to, the following: An insulated cement slab floor, insulation for walls and...

  12. 7 CFR 1436.6 - Eligible storage or handling equipment.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... eligible facility loan commodity, such as cleaners, moisture testers, and heat detectors; (4) Electrical... moisture testers, and heat detectors; (vii) Electrical equipment, including labor and materials for..., but are not limited to, the following: An insulated cement slab floor, insulation for walls and...

  13. 7 CFR 1436.6 - Eligible storage or handling equipment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... stored eligible facility loan commodity, such as cleaners, moisture testers, and heat detectors; (4... moisture testers, and heat detectors; (vii) Electrical equipment, including labor and materials for..., but are not limited to, the following: An insulated cement slab floor, insulation for walls and...

  14. 7 CFR 1436.6 - Eligible storage or handling equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... eligible facility loan commodity, such as cleaners, moisture testers, and heat detectors; (4) Electrical... moisture testers, and heat detectors; (vii) Electrical equipment, including labor and materials for..., but are not limited to, the following: An insulated cement slab floor, insulation for walls and...

  15. The Combine Use of Semi-destructive and Non-destructive Methods for Tiled Floor Diagnostics

    NASA Astrophysics Data System (ADS)

    Štainbruch, Jakub; Bayer, Karol; Jiroušek, Tomáš; Červinka, Josef

    2017-04-01

    The combination of semi-destructive and non-destructive methods was used to asset the conditions of a tiled floor in the historical monument Minaret, situated in the park complex of the Chateau Lednice (South Moravia Region, Czech Republic), before its renovation. Another set of measurements is going to be performed after the conservation works are finished. (The comparison of the results collected during pre- and post-remediation measurements will be known and presented during the General Assembly meeting in Wien.) The diagnostic complex of methods consisted of photogrammetry, resistivity drilling and georadar. The survey was aimed to contour extends of air gaps beneath the tiles and the efficiency of filling gaps by means of injection, consolidation and gluing individual layers. The state chateau Lednice creates a part of the Lednice-Valtice precinct, a UNESCO landmark, and belongs among the greatest historic monuments in Southern Moravia. In the chateau park there is a romantic observation tower in the shape of a minaret built according to the plans of Josef Hardtmuth between 1798-1804. The Minaret has been extensively renovated for many decades including the restoration of mosaic floors from Venetian terazzo. During the static works of the Minaret building between 1999-2000, the mosaic floors in the rooms on the second floor were transferred and put back onto concrete slabs. Specifically, the floor was cut up to tiles and these were glued to square slabs which were then attached to the base plate. The transfer was not successful and the floor restoration was finalized between 2016-2017. The damage consisted in separating the original floor from the concrete plate which led to creating gaps. Furthermore, the layers of the floor were not compact. It was necessary to fill the gaps and consolidate and glue the layers. The existence of air gap between individual layers of the tiles and their degradation was detected using two different diagnostic methods: semi-destructive resistivity drilling, and non-destructive georadar, and the results were compared. Floors were measured by 3D laser scanning technology and captured by the camera before reconstruction work. Using SFM photogrammetry were achieved results: ortomozaik (0.3 mm / pix) and DEM (0.6 mm / pix). These results were a basis for restoration work and also allow comparisons with the original state at any stage of the project. Drilling resistance measurement is used for indirect determination of strength profile based on resistance to drilling depending on into the depth. The observed resistance to drilling correlates with the strength and toughness of the measured material. The method is referred as a micro- or semi-invasive, since sampling is not necessary and but the drilling diameter is usually 3-5 mm. The ultrasonic measurement consists in the measuring of the longitude as well as the transverse waves - velocity, shape, amplitude. The propagation velocity is a characteristic values for the material influenced by its composition and compactness. Georadar (GPR) is a high frequency electromagnetic pulse method. For measurement the GPR RAMAC system coupled with 1600 MHz shielded antenna was used. Two tiles (one with defects and one in relatively good condition) were surveyed in a regular grid of perpendicular lines 5 cm separated. Data were processed by means of ReflexW software and performed in the form of cross sections and amplitude maps. The map of the amplitude summed over a time window 1 - 1,4 ns (representing the intensity of the reflection from the tiles bottom) gave good result. The areas of registered relatively high amplitudes correspond with the position of airgaps. A correlation was observed between the results of different survey methods.

  16. 8. PHOTOCOPY, ARCHITECTURAL FLOOR PLAN AND DETAIL DRAWING OF UNDERGROUND ...

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

    8. PHOTOCOPY, ARCHITECTURAL FLOOR PLAN AND DETAIL DRAWING OF UNDERGROUND STORAGE MAGAZINES AND LAUNCHER-LOADER ASSEMBLIES. - NIKE Missile Base SL-40, Underground Storage Magazines & Launcher-Loader Assemblies, Southwesternmost end of launch area, Hecker, Monroe County, IL

  17. 72. SECOND FLOOR, HEATER ROOM ENTRANCE (UPPER RIGHT) AND STEEL, ...

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

    72. SECOND FLOOR, HEATER ROOM ENTRANCE (UPPER RIGHT) AND STEEL, CONCRETE, BRICK, AND SPRING AIR CONDITIONER BASE, BAY 31-32/4 SOUTH, TO WEST - Ford Motor Company Edgewater Assembly Plant, Assembly Building, 309 River Road, Edgewater, Bergen County, NJ

  18. SOUTHERN END OF ASSEMBLY PLANT, LOOKING N ON SECOND FLOOR, ...

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

    SOUTHERN END OF ASSEMBLY PLANT, LOOKING N ON SECOND FLOOR, WHICH DID NOT EXIST ON DURING SHIP BUILDING DAYS. NOTE VEHICLE ELEVATOR. ABOVE AND TO THE LEFT IS SHIP BUILDING BALCONY. - B Building, 3001 Miller Road, Dearborn, MI

  19. 16. VIEW TO NORTHEAST OF SECONDFLOOR ASSEMBLY AREA FROM NEAR ...

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

    16. VIEW TO NORTHEAST OF SECOND-FLOOR ASSEMBLY AREA FROM NEAR SOUTHWEST WEST. NOTE DIFFERENCE IN ROOF STRUCTURE BETWEEN SAWTOOTH SKYLIGHTS OVER MOST OF THE SECOND FLOOR (RIGHT) AND THE PORTION OF THE ROOF RUNNING ALONG THE WEST EDGE OF THE BUILDING (LEFT). - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  20. 62. Neg. No. F75A, Jun 18, 1930, INTERIORWAREHOUSE, 1ST FLOOR, ...

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

    62. Neg. No. F-75A, Jun 18, 1930, INTERIOR-WAREHOUSE, 1ST FLOOR, STORAGE OF AUTOMOBILE COMPONENTS - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  1. 7 CFR 1924.9 - Inspection of development work.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... during the placement of concrete footings or monolithic footings and floor slabs. At this point, foundation excavations are complete, forms or trenches and steel are ready for concrete placement and the... prior to or during the placement of concrete, the County Supervisor or District Director will make the...

  2. A Preliminary Experimental Study on Vibration Responses of Foamed Concrete Composite Slabs

    NASA Astrophysics Data System (ADS)

    Rum, R. H. M.; Jaini, Z. M.; Ghaffar, N. H. Abd; Rahman, N. Abd

    2017-11-01

    In recent years, composite slab has received utmost demand as a floor system in the construction industry. The composite slab is an economical type of structure and able to accelerate the construction process. Basically, the composite slab can be casting by using a combination of corrugated steel deck and normal concrete in which selfweight represents a very large proportion of the total action. Therefore, foamed concrete become an attractive alternative to be utilized as a replacement of normal concrete. However, foamed concrete has high flexibility due to the presence of large amount of air-void and low modulus elasticity. It may result in vibration responses being greater. Hence, this experimental study investigates the vibration responses of composite slab made of corrugated steel deck and foamed concrete. The specimens were prepared with dimension of 750mm width, 1600mm length and 125mm thickness. The hammer-impact test was conducted to obtain the acceleration-time history. The analysis revealed that the first natural frequency is around 27.97 Hz to 40.94 Hz, while the maximum acceleration reaches 1.31 m/s2 to 1.88 m/s2. The first mode shape depicts normal pattern and favourable agreement of deformation.

  3. Assembly room, bunkhouse first floor interior. Vent pipe for missing ...

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

    Assembly room, bunkhouse first floor interior. Vent pipe for missing heating stove exited through opening into chimney, seen on the far wall. Walls are exposed studs and bracing with board and battan on the exterior and interior sides. - Sespe Ranch, Bunkhouse, 2896 Telegraph Road, Fillmore, Ventura County, CA

  4. Corium protection assembly

    DOEpatents

    Gou, Perng-Fei; Townsend, Harold E.; Barbanti, Giancarlo

    1994-01-01

    A corium protection assembly includes a perforated base grid disposed below a pressure vessel containing a nuclear reactor core and spaced vertically above a containment vessel floor to define a sump therebetween. A plurality of layers of protective blocks are disposed on the grid for protecting the containment vessel floor from the corium.

  5. 13. VIEW OF AREAWAY 104 LOOKING SOUTHEAST, TOWARD ANIMAL QUARTERS. ...

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

    13. VIEW OF AREAWAY 104 LOOKING SOUTHEAST, TOWARD ANIMAL QUARTERS. WOOD STUD WALL WITH WIRE MESH INFILL HAS BEEN ADDED. HORIZONTAL WOOD PANELING ON WALLS IS PAINTED. FLOOR IS CONCRETE SLAB. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA

  6. 75 FR 38148 - Finding of No Significant Impact Related to Approval of the Mallinckrodt C-T Phase 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... selected the following decommissioning strategy: (1) Remediate remaining floor slabs and subsurface soils... has committed to conducting a FSS consistent with the approach presented in the Multi-Agency Radiation...) climatology, meteorology, and air quality; (3) geology and soils; (4) water resources; (5) biological...

  7. Differential effects of Phe19 and Phe20 on fibril formation by amyloidogenic peptide A beta 16-22 (Ac-KLVFFAE-NH2).

    PubMed

    Inouye, Hideyo; Gleason, Katherine A; Zhang, Dong; Decatur, Sean M; Kirschner, Daniel A

    2010-08-01

    The sequence KLVFFAE (A beta 16-22) in Alzheimer's beta-amyloid is thought to be a core beta-structure that could act as a template for folding other parts of the polypeptide or molecules into fibrillar assemblies rich in beta-sheet. To elucidate the mechanism of the initial folding process, we undertook combined X-ray fiber/powder diffraction and infrared (IR) spectroscopy to analyze lyophilized A beta 16-22 and solubilized/dried peptide containing nitrile probes at F19 and/or F20. Solubilized/dried wild-type (WT) A beta 16-22 and the peptide containing cyanophenylalanine at F19 (19CN) or at F20 (20CN) gave fiber patterns consistent with slab-like beta-crystallites that were cylindrically averaged around the axis parallel to the polypeptide chain direction. The WT and 19CN assemblies showed 30-A period arrays arising from the stacking of the slabs along the peptide chain direction, whereas the 20CN assemblies lacked any such stacking. The electron density projection along the peptide chain direction indicated similar side-chain dispositions for WT and 20CN, but not for 19CN. These X-ray results and modeling imply that in the assembly of WT A beta 16-22 the F19 side chain is localized within the intersheet space and is involved in hydrophobic contact with amino acids across the intersheet space, whereas the F20 side chain localized near the slab surface is less important for the intersheet interaction, but involved in slab stacking. IR observations for the same peptides in dilute solution showed a greater degree of hydrogen bonding for the nitrile groups in 20CN than in 19CN, supporting this interpretation. (c) 2010 Wiley-Liss, Inc.

  8. View southeast of weldment assembly floor in structures shop, building ...

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

    View southeast of weldment assembly floor in structures shop, building 57; the floor is fabricated of cast iron and features a grillwork of 1 1/2 square holes which are used as sockets for gripping positioning or lock down pins; a lock down pin is shown left and below the center of the photograph; the vertical section of the pin is placed into a hole in the cast steel floor while the angles section of the pin rests on the piece under construction; the pin is hammered into the hole and spring tension in the pin holds the work piece in position. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Structure Shop, League Island, Philadelphia, Philadelphia County, PA

  9. Incorrect installation and use of materials as the cause of a severe air pollution incident in a school building.

    PubMed

    Rella, Rocco; Sturaro, Alberto; Vianello, Alvise

    2014-07-15

    The proofing treatment of the floor slabs with a solvent based material and successive treatment with epoxy resin resulted in significant air contamination in a primary school. The contamination caused illnesses in many occupants of school. The GC/MS investigations of the air showed the presence of indane and other aromatic solvents, which was unusual as they are not correlated to outdoor pollution and derived from inner layers of the new flooring. The total concentration of these chemicals in air was in the order of several mg/m(3). Copyright © 2014 Elsevier B.V. All rights reserved.

  10. 76 FR 33782 - Multilayered Wood Flooring From China; Scheduling of the Final Phase of Countervailing Duty and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-09

    ... Wood Flooring From China; Scheduling of the Final Phase of Countervailing Duty and Antidumping... retarded, by reason of subsidized and less-than-fair-value imports from China of multilayered wood flooring... as `` * * * multilayered wood flooring, composed of an assembly of two or more layers or plies of...

  11. A&M. TAN607 second floor plan for cold assembly area. Metallurgical ...

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

    A&M. TAN-607 second floor plan for cold assembly area. Metallurgical lab, chemistry lab, nuclear instrument lab, equipment rooms. Ralph M. Parsons 902-ANP-607-A 102. Date: December 1952. Approved by INEEL Classification Office for public release. INEEL index code no. 034-0607-693-106754 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  12. 20. VIEW TO WEST OF INTERIOR OF CRANEWAY WITH TOW ...

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

    20. VIEW TO WEST OF INTERIOR OF CRANEWAY WITH TOW TRAVELING BRIDGE CRANES (ONE OVERHEAD IN FOREGROUND AND ONE OVERHEAD IN BACKGROUNDS). NOTE WOOD BLOCK PAVING ON THE FLOOR. FIRST FLOOR ASSEMBLY AREA IS THE SPACE IN THE BACKGROUND ON THE RIGHT. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  13. 48 CFR 225.7003-3 - Exceptions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., slab, wire, plate, and sheet, that have not been incorporated into end items, subsystems, assemblies... are incorporated into COTS end items, subsystems, or assemblies; (C) Commercially available high... COTS end items or subsystems (see PGI 225.7003-3(b)(6) for a table of applicability of specialty metals...

  14. DOE Office of Scientific and Technical Information (OSTI.GOV)

    none,

    This case study describes a DOE Zero Energy Ready Home in Greenbank, Washington that scored HERS 37 without PV and a -5 with PV. This 1,955 ft2 custom home has 6.5-inch structural insulated panel (SIPs) walls, a 10.25-inch SIPS roof, an R-20 insulated slab, a 2-ton ground source heat pump, radiant floor heat, 7.1 kWh PV, and triple-pane windows.

  15. Conceptual design of new metrology laboratories for the National Physical Laboratory, United Kingdom

    NASA Astrophysics Data System (ADS)

    Manning, Christopher J.

    1994-10-01

    The National Physical Laboratory is planning to house the Division of Mechanical and Optical Metrology and the Division of Material Metrology in a new purpose built laboratory building on its site at Teddington, London, England. The scientific staff were involved in identifying and agreeing the vibration performance requirements of the conceptual design. This was complemented by an extensive surgery of vibration levels within the existing facilities and ambient vibration studies at the proposed site. At one end of the site there is significant vibration input from road traffic. Some of the test equipment is also in itself a source of vibration input. These factors, together with normal occupancy inputs, footfalls and door slams, and a highly serviced building led to vibration being dominant in influencing the structural form. The resulting structural concept comprises three separate structural elements for vibration and geotechnical reasons. The laboratories most sensitive to disturbance by vibration are located at the end of the site farthest from local roads on a massive ground bearing slab. Less sensitive laboratories and those containing vibration sources are located on a massive slab in deep, piled foundations. A common central plant area is located alongside on its own massive slab. Medium sensitivity laboratories and offices are located at first floor level on a reinforced concrete suspended floor of maximum stiffness per unit mass. The whole design has been such as to permit upgrading of areas, eg office to laboratory; laboratory to `high sensitivity' laboratory, to cater for changes in future use of the building.

  16. 6. SAWTOOTH WINDOW RANKS ABOVE ASSEMBLY LINES, WATER TOWER, AND ...

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

    6. SAWTOOTH WINDOW RANKS ABOVE ASSEMBLY LINES, WATER TOWER, AND SECOND FLOOR WAREHOUSE STRUCTURE. VIEW TO SOUTH-SOUTHEAST. - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  17. 102. JOB NO. 1347F, SHEET 3, 1927, ASSEMBLY BUILDING; FORD ...

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

    102. JOB NO. 1347-F, SHEET 3, 1927, ASSEMBLY BUILDING; FORD MOTOR COMPANY; FIRST FLOOR PLAN - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  18. Clean then Assemble Versus Assemble then Clean: Several Comparisons

    NASA Technical Reports Server (NTRS)

    Welker, Roger W.

    2004-01-01

    Cleanliness of manufactured parts and assemblies is a significant issue in many industries including disk drives, semiconductors, aerospace, and medical devices. Clean manufacturing requires cleanroom floor space and cleaning technology that are both expensive to own and expensive to operate. Strategies to reduce these costs are an important consideration. One strategy shown to be effective at reducing costs is to assemble parts into subassemblies and then clean the subassembly, rather than clean the individual parts first and then assemble them. One advantage is that assembly outside of the cleanroom reduces the amount of cleanroom floor space and its associated operating cost premium. A second advantage is that this strategy reduces the number of individual parts that must be cleaned prior to assembly, reducing the number of cleaning baskets, handling and, possibly, reducing the number of cleaners. The assemble then clean strategy also results in a part that is significantly cleaner because contamination generated during the assembly steps are more effectively removed that normally can be achieved by hand wiping after assembly in the cleanroom.

  19. Walking beam furnace well-way slot covers at Rouge Steel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Campbell, F. Jr.; Meinzinger, A.D.; Faust, C.H.

    1993-07-01

    Rouge Steel's 68-in. hot strip mill is served by three walking beam slab reheat furnaces. The first two were commissioned in 1974 and the third was installed in 1980. During the period 1979 to 1981, an intensive plant-wide energy management program to reduce energy consumption was undertaken. A major part of that program involved a comprehensive upgrading of refractory and insulation systems utilized in the walking beam reheat furnaces. A durable system for reducing heat losses through the well-way floor openings associated with walking beam slab reheat furnaces has, in addition to 4 to 5% savings in fuel consumption, reducedmore » maintenance costs. Payback is achieved in four to five months.« less

  20. Geometrical optics of dense aerosols: forming dense plasma slabs.

    PubMed

    Hay, Michael J; Valeo, Ernest J; Fisch, Nathaniel J

    2013-11-01

    Assembling a freestanding, sharp-edged slab of homogeneous material that is much denser than gas, but much more rarefied than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed field, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the finite particle density reduces the effective Stokes number of the flow, a critical result for controlled focusing.

  1. 609th Iraqi National Guard Battalion Garrison, Thi Qar Governorate, Iraq

    DTIC Science & Technology

    2006-07-25

    views of structural members (reinforced concrete footers, columns , beams , floor, and roof slabs). Mechanical drawings included plumbing plans and...well as reinforced concrete columns and beams . The exterior walls were constructed with sand lime block. Although the assessment team did not...foundation support for the perimeter wall included reinforced concrete footers to support the columns and a reinforced concrete tie beam under the wall

  2. Nuclear reactor control room construction

    DOEpatents

    Lamuro, R.C.; Orr, R.

    1993-11-16

    A control room for a nuclear plant is disclosed. In the control room, objects labelled 12, 20, 22, 26, 30 in the drawing are no less than four inches from walls labelled 10.2. A ceiling contains cooling fins that extend downwards toward the floor from metal plates. A concrete slab is poured over the plates. Studs are welded to the plates and are encased in the concrete. 6 figures.

  3. Nuclear reactor control room construction

    DOEpatents

    Lamuro, Robert C.; Orr, Richard

    1993-01-01

    A control room 10 for a nuclear plant is disclosed. In the control room, objects 12, 20, 22, 26, 30 are no less than four inches from walls 10.2. A ceiling 32 contains cooling fins 35 that extend downwards toward the floor from metal plates 34. A concrete slab 33 is poured over the plates. Studs 36 are welded to the plates and are encased in the concrete.

  4. Surface Textures and Features Indicative of Endogenous Growth at the McCartys Flow Field, NM, as an Analog to Martian Volcanic Plains

    NASA Technical Reports Server (NTRS)

    Bleacher, Jacob E.; Crumpler, L. S.; Garry, W. B.; Zimbelman, J. R.; Self, S.; Aubele, J. C.

    2012-01-01

    Basaltic lavas typically form channels or tubes, which are recognized on the Earth and Mars. Although largely unrecognized in the planetary community, terrestrial inflated sheet flows also display morphologies that share many commonalities with lava plains on Mars. The McCartys lava flow field is among the youngest (approx.3000 yrs) basaltic flows in the continental United States. The southwest sections of the flow displays smooth, flat-topped plateaus with irregularly shaped pits and hummocky inter-plateau units that form a polygonal surface. Plateaus are typically elongate in map view, up to 20 m high and display lineations within the glassy crust. Lineated surfaces occasionally display small < 1m diameter lava coils. Lineations are generally straight and parallel each other, sometimes for over 100 meters. The boundaries between plateaus and depressions are also lineated and tilted to angles sometimes approaching vertical. Plateau-parallel cracks, sometimes containing squeeze-ups, mark the boundary between tilted crust and plateau. Some plateau depressions display level floors with hummocky surfaces, while some are bowl shaped with floors covered in broken lava slabs. The lower walls of pits sometimes display lateral, sagged lava wedges. Infrequently, pit floors display the upper portion of a tumulus from an older flow. In some places the surface crust has been disrupted forming a slabby texture. Slabs are typically on the scale of a meter or less across and no less than 7-10 cm thick. The slabs preserve the lineated textures of the undisturbed plateau crust. It appears that this style of terrain represents the emplacement of an extensive sheet that experiences inflation episodes within preferred regions where lateral spreading of the sheet is inhibited, thereby forming plateaus. Rough surfaces represent inflation-related disruption of pahoehoe lava and not a a lava. Depressions are often the result of non-inflation and can be clearly identified by lateral squeeze-outs along the pit walls that form when the rising crust exposes the still liquid core of the sheet. The plains of Tharsis and Elysium, Mars, display many analogous features

  5. Looking for Microbes in a Spacecraft Assembly Clean Room

    NASA Image and Video Library

    2013-11-06

    A microbiologist collects a swab sample from the floor of a spacecraft assembly clean room at NASA Jet Propulsion Laboratory where samples such as this are taken frequently during the assembly of a spacecraft and analyzed.

  6. Experimental Building Information Models

    DTIC Science & Technology

    2011-09-01

    ER D C/ CE RL C R- 11 -2 Experimental Building Information Models Co ns tr uc tio n En gi ne er in g R es ea rc h La bo ra to ry...Foundations, floor slabs , framing, stairs and elevators. • Mechanical: Heating, ventilating, and air conditioning equipment, thermostats, ducts, and...Single Flush .rvt Other standards and considerations – In a traditional cad environment, drawing layers are used to organize drawing objects and

  7. Long-term prediction of creep strains of mineral wool slabs under constant compressive stress

    NASA Astrophysics Data System (ADS)

    Gnip, Ivan; Vaitkus, Saulius; Keršulis, Vladislovas; Vėjelis, Sigitas

    2012-02-01

    The results obtained in determining the creep strain of mineral wool slabs under compressive stress, used for insulating flat roofs and facades, cast-in-place floors, curtain and external basement walls, as well as for sound insulation of floors, are presented. The creep strain tests were conducted under a compressive stress of σ c =0.35 σ 10%. Interval forecasting of creep strain was made by extrapolating the creep behaviour and approximated in accordance with EN 1606 by a power equation and reduced to a linear form using logarithms. This was performed for a lead time of 10 years. The extension of the range of the confidence interval due to discount of the prediction data, i.e. a decrease in their informativity was allowed for by an additional coefficient. Analysis of the experimental data obtained from the tests having 65 and 122 days duration showed that the prediction of creep strains for 10 years can be made based on data obtained in experiments with durations shorter than the 122 days as specified by EN 13162. Interval prediction of creep strains (with a confidence probability of 90%) was based on using the mean square deviation of the actual direct observations of creep strains in logarithmic form to have the linear trend in a retrospective area.

  8. 14. VIEW TO SOUTHWEST AT NORTH END OF SECONDFLOOR ASSEMBLY ...

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

    14. VIEW TO SOUTHWEST AT NORTH END OF SECOND-FLOOR ASSEMBLY AREA. VIEW SHOWS DETAILS OF SAWTOOTH ROOF STRUCTURE. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  9. Evaluation of the deflected mode of the monolithic span pieces and preassembled slabs combined action

    NASA Astrophysics Data System (ADS)

    Roshchina, Svetlana; Ezzi, Hisham; Shishov, Ivan; Lukin, Mikhail; Sergeev, Michael

    2017-10-01

    In single-story industrial buildings, the cost of roof covering comprises 40-55% of the total cost of the buildings. Therefore, research, development and application of new structural forms of reinforced concrete rafter structures, that allow to reduce material consumption and reduce the sub-assembly weight of structures, are the main tasks in the field of improving the existing generic solutions. The article suggests a method for estimating the relieving effect in the rafter structure as the result of combined deformation of the roof slabs with the end arrises. Calculated and experimental method for determining the stress and strain state of the rafter structure upper belt and the roof slabs with regard to their rigid connection has been proposed. A model of a highly effective roof structure providing a significant reduction in the construction height of the roofing and the cubic content of the building at the same time allowing to include the end arrises and a part of the slabs shelves with the help of the monolithic concrete has been proposed. The proposed prefabricated monolithic concrete rafter structure and its rigid connection with ribbed slabs allows to reduce the consumption of the prestressed slabs reinforcement by 50%.

  10. Deployment, release and recovery of ocean riser pipes

    DOEpatents

    Person, Abraham; Wetmore, Sherman B.; McNary, James F.

    1980-11-18

    An ocean thermal energy conversion facility includes a long pipe assembly which is supported at its upper end by the hull of the floating facility. Cold water flows to the facility from deep in the ocean. The pipe assembly comprises an elongate pipe construction and a weight connected to the lower end of the construction by a line of selected length. A floatation collar is connected to the construction at its upper end to cause the construction to have positive buoyancy and a center of buoyancy closer to the upper end of the construction than its center of mass. The weight renders the entire pipe assembly negatively buoyant. In the event that support of the pipe assembly should be lost, as by release of the assembly from the facility hull in an emergency, the assembly sinks to the ocean floor where it is moored by the weight. The pipe construction floats submerged above the ocean floor in a substantially vertical attitude which facilitates recovery of the assembly.

  11. 16. VIEW OF FIRST FLOOR EAST OPERATING GALLERY. NOTE THE ...

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

    16. VIEW OF FIRST FLOOR EAST OPERATING GALLERY. NOTE THE SERIES OF MANIPULATOR ARMS ALONG THE LEFT WALL. - Nevada Test Site, Engine Maintenance Assembly & Disassembly Facility, Area 25, Jackass Flats, Mercury, Nye County, NV

  12. View from second floor platform looking up at subsequent platforms. ...

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

    View from second floor platform looking up at subsequent platforms. Note the Shuttle assembly outlined by the platform edges. - Marshall Space Flight Center, Saturn V Dynamic Test Facility, East Test Area, Huntsville, Madison County, AL

  13. ARCHITECTURAL, 777M, PHYSICS ASSEMBLY LABORATORY BUILDING, PLAN OF +13’1” AND ...

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

    ARCHITECTURAL, 777-M, PHYSICS ASSEMBLY LABORATORY BUILDING, PLAN OF +13’-1” AND +27’-0” FLOOR LEVELS (W157114) - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  14. A&M. TAN607 first floor plan for cold assembly area. Shows ...

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

    A&M. TAN-607 first floor plan for cold assembly area. Shows special source vaults, X-ray room, instrument shops, and positions of large machines in component test laboratory. This drawing was re-drawn to show conditions in 1994. Ralph M. Parsons 902-3-ANP-607-A 100. Date of original: December 1952. Approved by INEEL Classification Office for public release. INEEL index code no. 034-060-00-693-106752 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  15. 15. VIEW TO NORTHWEST OF SECONDFLOOR ASSEMBLY AREA FROM NEAR ...

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

    15. VIEW TO NORTHWEST OF SECOND-FLOOR ASSEMBLY AREA FROM NEAR MIDDLE OF EAST WALL. VIEW SHOWS DETAIL OF NORTH-FACING SKYLIGHTS. - Rosie the Riveter National Historical Park, Ford Assembly Plant, 1400 Harbour Way South, Richmond, Contra Costa County, CA

  16. Blast Loading and Response of Underground Concrete-Arch Protective Structures

    DTIC Science & Technology

    1959-06-05

    to approximate the load due to pasive earth pressure developed in the region of outward deflection of the arch. This Is assumed as a radial sinus...to represent a specimen from the wall matter , and preserve the gradation. Sufficient live reinforcement, the floor-slab reinforcement, and the storage...chemicals, or other foreign materials shall cleaned of latance, foreign matter , and loose parti- not be mixed with the concrete to prevent freezing. cles

  17. GENERAL VIEW OF THE MAIN FLOOR LEVEL, PLATFORM DSOUTH, HB3, ...

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

    GENERAL VIEW OF THE MAIN FLOOR LEVEL, PLATFORM D-SOUTH, HB-3, FACING NORTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  18. Performance Support on the Shop Floor.

    ERIC Educational Resources Information Center

    Kasvi, Jyrki J. J.; Vartiainen, Matti

    2000-01-01

    Discussion of performance support on the shop floor highlights four support systems for assembly lines that incorporate personal computer workstations in local area networks and use multimedia documents. Considers new customer-focused production paradigms; organizational learning; knowledge development; and electronic performance support systems…

  19. DETAIL VIEW OF VIDEO CAMERA, MAIN FLOOR LEVEL, PLATFORM ESOUTH, ...

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

    DETAIL VIEW OF VIDEO CAMERA, MAIN FLOOR LEVEL, PLATFORM E-SOUTH, HB-3, FACING SOUTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  20. Measurements of angular flux on surface of Li/sub 2/O slab assemblies and their analysis by a direct integration transport code ''BERMUDA''

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Maekawa, H.; Oyama, Y.

    1983-09-01

    Angle-dependent neutron leakage spectra above 0.5 MeV from Li/sub 2/O slab assemblies were measured accurately by the time-of-flight method. The measured angles were 0/sup 0/, 12.2/sup 0/, 24.9/sup 0/, 41.8/sup 0/ and 66.8/sup 0/. The sizes of Li/sub 2/O assemblies were 31.4 cm in equivalent radius and 5.06, 20.24 and 40.48 cm in thickness. The data were analyzed by a new transport code ''BERMUDA-2DN''. Time-independent transport equation is solved for two-dimensional, cylindrical, multi-regional geometry using the direct integration method in a multi-group model. The group transfer kernels are accurately obtained from the double-differential cross section data without using Legendre expansion.more » The results were compared absolutely. While there exist discrepancies partially, the calculational spectra agree well with the experimental ones as a whole. The BERMUDA code was demonstrated to be useful for the analyses of the fusion neutronics and shielding.« less

  1. Department of the Navy. FY 1994/FY 1995 Biennial Budget Estimates. Military Construction Program. FY 1994

    DTIC Science & Technology

    1992-01-01

    3 are severely deteriorated. The concrete deck and supporting wood -pile structure are nearing the end of their life cycle. Both piers are to be...PROPOSED CONSTRUCTION One-story building with concrete foundation walls, load bearing masonry walls, and concrete floors; roof with wood truss framing...concrete building addition; concrete foundation and slab on grade; wood truss roof; 750 KVA. 3 phase transformer; utilities; concrete and storm drain. 11

  2. Analysis of Latest Experience in Design of Industrial Buildings Reconstruction by Constructing Additional Interfloor Overlaps

    NASA Astrophysics Data System (ADS)

    Peshnina, I.; Sinitsina, O.

    2017-11-01

    The study relevance is determined by the increasing interest in reconstruction of city historical centers and located in the area of industrial buildings the functional profile of which needs to be changed. The problem of obtaining extra usable spaces in the historical centers of cities is solved by raising the number of storeys in the buildings which can be achieved by the construction of additional built-in inter-floor overlaps. The article is dedicated to the analysis of the recent years’ experience in reconstruction design involving this method in our country and abroad, in the Netherlands, in particular. The article presents the results of the analysis of the experience in reconstruction of the objects by constructing additional inter-floor overlaps and aims to define the optimum construction solution for built-in inter-floor overlapping and to develop non-existing solutions for wide application of this method in the reconstruction of a building with non-unified and unmodulated parameters. It was determined as expedient to apply a monolith reinforced concrete slab with the use of steel profiled flooring as a formwork and reinforcement and steel beams designed as “Built-in Beams” for the construction of built-in inter-floor overlaps in reconstruction. The article will be useful for specialists doing research in the sphere of reconstruction of the buildings and for the practical activity of design engineers.

  3. VIEW OF PDP ROOM WITH FLOOR AT LEVEL +15’ AND ...

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

    VIEW OF PDP ROOM WITH FLOOR AT LEVEL +15’ AND SHEAVE RACK ABOVE, LOOKING SOUTH. ON THE LEFT SIDE, CABLES GO THROUGH THE WALL TOWARD THE PDP CONTROL ROOM AREA - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

  4. 65. Neg. No. F99, Dec 27, 1931, INTERIORPRESSED STEEL BUILDING ...

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

    65. Neg. No. F-99, Dec 27, 1931, INTERIOR-PRESSED STEEL BUILDING FACING SOUTH TOWARD WAREHOUSE AND ASSEMBLY BUILDING 1ST FLOOR, EAST SIDE FACING SOUTH, SHOWING PRESSED STEEL MACHINERY AND RAILROAD CARS - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  5. 29 CFR 1926.754 - Structural steel assembly.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... connectors on composite floors, roofs and bridge decks. When shear connectors are used in construction of composite floors, roofs and bridge decks, employees shall lay out and install the shear connectors after the... requirements of paragraph (e)(3)(i) of this section. (4) Decking gaps around columns. Wire mesh, exterior...

  6. 29 CFR 1926.754 - Structural steel assembly.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... connectors on composite floors, roofs and bridge decks. When shear connectors are used in construction of composite floors, roofs and bridge decks, employees shall lay out and install the shear connectors after the... requirements of paragraph (e)(3)(i) of this section. (4) Decking gaps around columns. Wire mesh, exterior...

  7. 29 CFR 1926.754 - Structural steel assembly.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... connectors on composite floors, roofs and bridge decks. When shear connectors are used in construction of composite floors, roofs and bridge decks, employees shall lay out and install the shear connectors after the... requirements of paragraph (e)(3)(i) of this section. (4) Decking gaps around columns. Wire mesh, exterior...

  8. The Ophiolite Problem, Is It Really a Problem?

    NASA Astrophysics Data System (ADS)

    Casey, J. F.; Dewey, J. F.

    2009-12-01

    Ophiolites and ophiolite complexes have been recognized as having an oceanic affinity or origin since the classic work of Ian Gass in the 1950’s on the Troodos Complex. A problem has been that the term ophiolite has included a very diverse range of meanings from obscure slivers of mafic and ultramafic rocks of doubtful origin in orogenic belts to large obducted slabs with the full range (Coleman, 1972), from base to top, of lherzolite/ariegite, harzburgite, dunite, gabbro, sheeted dyke complex, pillow basalts, and sediments, commonly with a two-pyroxene mafic granulite as a thin aureole attached to the base of the complex. Large obducted ophiolite slabs are mainly early Ordovician and mid-Cretaceous. The principal enigma of these obducted slabs is that they clearly must have been generated by some form of organized sea-floor spreading/plate-accretion, such as may be envisioned for the oceanic ridges, yet the volcanics commonly have arc affinity (Miyashiro) with boninites (high-temperature/low-pressure, high Mg and Si andesites), which suggest a forearc origin. Our model hinges on the PT conditions under which boninites form. Many ophiolites have complexly-deformed associated assemblages that suggest fracture zone/transform geology, which in turn has led to models involving the nucleation of subduction zones on fracture zones/transforms. Hitherto, arc-related sea-floor-spreading has been considered to be either pre-arc (fore-arc boninites) or post-arc (classic Karig-style back arc basins that split arcs). We propose a new model with syn-arc boninites that involves a stable ridge/trench/trench triple junction, the ridge being between the two upper plates. The direction of subduction must be oblique with a different sense in the two subduction zones and the oblique subduction cannot be partitioned into trench orthogonal and parallel strike-slip components. As the ridge spreads, new oceanic lithosphere is created within the forearc, the arc and fore-arc lengthen significantly, and a syn-arc ophiolite complex is generated that ages along arc-strike; a distinctive diachronous boninite/arc volcanic stratigraphy develops. Dikes in the ophiolite are oblique to the trench as are magnetic anomalies in the “back-arc” basin. Boninites and high-mg andesites are generated in the fore-arc under the aqueous, low pressure/high temperature, regime at the ridge above the dehydrating slab or where a ridge subducts beneath the forearc. The mafic protolith, garnet/two pyroxene, aureole is generated in and sliced from the subducting slab and attached to the base of the overriding lithosphere at about 1000°C, ten to twelve million years from the ridge axis, where the SSZ ophiolite is about ten to twelve kilometers thick, at which thickness of the ophiolite is buffered by the subducting slab. Obduction of the SSZ ophiolite with its subjacent aureole occurs whenever the oceanic arc attempts subduction of a stable continental margin.

  9. Cretaceous subduction in the Pyrenees: Iberian plate-kinematics in a mantle reference frame

    NASA Astrophysics Data System (ADS)

    Vissers, Reinoud; van Hinsbergen, Douwe; van der Meer, Douwe; Spakman, Wim

    2016-04-01

    During the Cretaceous, Iberia was a microplate separated from Laurasia and Gondwana by ridges and transforms, and by a convergent margin to its northeast along which the Pyrenean fold-thrust belt developed. As a microplate, Iberia underwent a well-defined but ill-understood Albian-Aptian ~ 35° counterclockwise rotation relative to Eurasia. Three competing kinematic scenarios for Iberian motion in the late Mesozoic are all compatible with the Pyrenean geological record and comprise (1) transtensional eastward motion of Iberia versus Eurasia, (2) strike-slip motion followed by orthogonal extension and (3) scissor-style opening of the Bay of Biscay coupled with subduction in the Pyrenean realm. The last scenario is the only one consistent with paleomagnetic and ocean floor anomaly constraints showing Iberia's rotation, but is criticized because the upper mantle below the Pyrenees contains no evidence for a subducted slab. Here we show that when taking absolute plate motions into account, Aptian oceanic subduction in the Pyrenees followed by Albian slab break-off should leave a slab remnant in the present-day mid-mantle below NW Africa instead of below the Pyrenees. Mantle tomography shows a positive seismic velocity anomaly that matches the predicted position and dimension of such a slab remnant between 1900 and 1500 km depth below Reggane in Southern Algeria. Seismic tomographic imaging of the mantle structure therefore does not falsify the Pyrenean subduction hypothesis, and provides no basis to discard marine magnetic and paleomagnetic constraints on Iberia's kinematic history. Slab break-off explains the well-dated Albian-Cenomanian high-temperature metamorphism in the Pyrenees that hitherto has been interpreted as an expression of continental break-up and hyperextension. We suspect that subduction in the Pyrenees may have played a key role in driving the rapid Aptian rotation of the Iberian microplate.

  10. Integrating surface and mantle constraints for palaeo-ocean evolution: a tour of the Arctic and adjacent regions (Arne Richter Award for Outstanding Young Scientists Lecture)

    NASA Astrophysics Data System (ADS)

    Shephard, Grace E.

    2016-04-01

    Plate tectonic reconstructions heavily rely on absolute motions derived from hotspot trails or palaeomagnetic data and ocean-floor magnetic anomaies and fracture-zone geometries to constrain the detailed history of ocean basins. However, as oceanic lithosphere is progressively recycled into the mantle, kinematic data regarding the history of these now extinct-oceans is lost. In order to better understand their evolution, novel workflows, which integrate a wide range of complementary yet independent geological and geophysical datasets from both the surface and deep mantle, must be utilised. In particular, the emergence of time-dependent, semi or self-consistent geodynamic models of ever-increasing temporal and spatial resolution are revealing some critical constraints on the evolution and fate of oceanic slabs. The tectonic evolution of the circum-Arctic is no exception; since the breakup of Pangea, this enigmatic region has seen major plate reorganizations and the opening and closure of several ocean basins. At the surface, a myriad of potential kinematic scenarios including polarity, timing, geometry and location of subduction have emerged, including for systems along continental margins and intra-oceanic settings. Furthermore, recent work has reignited a debate about the origins of 'anchor' slabs, such as the Farallon and Mongol-Okhotsk slabs, which have been used to refine absolute plate motions. Moving to the mantle, seismic tomography models reveal a region peppered with inferred slabs, however assumptions about their affinities and subduction location, timing, geometry and polarity are often made in isolation. Here, by integrating regional plate reconstructions with insights from seismic tomography, satellite derived gravity gradients, slab sinking rates and geochemistry, I explore some Mesozoic examples from the palaeo-Arctic, northern Panthalassa and western margin of North America, including evidence for a discrete and previously undescribed slab under present-day Greenland. While regional in focus, the methods and insights described have global applications and illustrate the power of an integrated approach.

  11. Low floor mass transit vehicle

    DOEpatents

    Emmons, J Bruce [Beverly Hills, MI; Blessing, Leonard J [Rochester, MI

    2004-02-03

    A mass transit vehicle includes a frame structure that provides an efficient and economical approach to providing a low floor bus. The inventive frame includes a stiff roof panel and a stiff floor panel. A plurality of generally vertical pillars extend between the roof and floor panels. A unique bracket arrangement is disclosed for connecting the pillars to the panels. Side panels are secured to the pillars and carry the shear stresses on the frame. A unique seating assembly that can be advantageously incorporated into the vehicle taking advantage of the load distributing features of the inventive frame is also disclosed.

  12. Indoor air quality and health problems associated with damp floor coverings.

    PubMed

    Tuomainen, Anneli; Seuri, Markku; Sieppi, Anne

    2004-04-01

    To study the relationship between a high incidence of bronchial asthma among employees working in an office building and an indoor air problem related to the degradation of polyvinyl chloride (PVC) floor coverings in the building. The indoor air measurements and results of renovations are also described. Employees' symptoms were surveyed by a questionnaire, and the incidence of asthma was calculated from the medical records for 1997-2000. The quality of indoor air was assessed by microbial sampling and by investigation of the building for possible moisture damage. Indoor air was sampled for volatile organic compounds (VOCs) through Tenax adsorbent tubes. In situ volatile emission measurements from the concrete floor were performed via the field and laboratory emission cell (FLEC) method. In an office with approximately 150 employees, eight new cases of asthma were found in 4 years. In addition, the workers complained of respiratory, conjunctival and nasal symptoms. Emissions indicating the degradation of plastic floor coverings (e.g. 2-ethyl-1-hexanol, 1-butanol) were found in the indoor air and floor material samples. The plastic floor coverings, adhesives and the levelling layers were carefully removed from 12 rooms. The VOCs had diffused into the underlying concrete slabs. The concrete was warmed to remove the diffused VOCs from these areas. After the repairs the concentrations of the VOCs indicating the degradation of PVC, decreased, as did the prevalence of the employees' symptoms and several asthma patients' need for medication. The workers in the office building complained of several respiratory, conjunctival and dermal symptoms. The incidence of adult-onset asthma was approximately nine-times higher than that among Finns employed in similar work. The most probable single cause of the indoor air problem was the degradation of the plastic floor coverings.

  13. Continental crustal growth and the supercontinental cycle: evidence from the Central Asian Orogenic Belt

    NASA Astrophysics Data System (ADS)

    Hong, Dawei; Zhang, Jisheng; Wang, Tao; Wang, Shiguang; Xie, Xilin

    2004-09-01

    Studies of supercontinental cycle are mainly concentrated on the assembly, breakup and dispersal of supercontinents, and studies of continental crustal growth largely on the growth and loss (recycling) of the crust. These two problems have long been studied separately from each other. The Paleozoic-Mesozoic granites in the Central Asian Orogenic Belt have commonly positive ɛNd values, implying large-scale continental crustal growth in the Phanerozoic. They coincided temporally and spatially with the Phanerozoic Pangea supercontinental cycle, and overlapped in space with the P-wave high- V anomalies and calculated positions of subducted slabs for the last 180 Ma, all this suggests that the Phanerozoic Laurasia supercontinental assembly was accompanied by large-scale continental crustal growth in central Asia. Based on these observations, this paper proposes that there may be close and original correlations between a supercontinental cycle, continental crustal growth and catastrophic slab avalanches in the mantle. In this model we suggest that rapid continental crustal growth occurred during supercontinent assembly, whereas during supercontinental breakup and dispersal new additions of the crust were balanced by losses, resulting in a steady state system. Supercontinental cycle and continental crustal growth are both governed by changing patterns of mantle convection.

  14. 31. INTERIOR VIEW TO THE EAST OF THE FIRST FLOOR ...

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

    31. INTERIOR VIEW TO THE EAST OF THE FIRST FLOOR SOUTH CORRIDOR AND VIEWING GALLERY TO THE DISASSEMBLY BAY AND POST-MORTEM CELLS. VIEWING STATIONS ARE ON BOTH SIDES OF THE CORRIDOR. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  15. 38. INTERIOR VIEW TO THE NORTHWEST OF THE SECOND FLOOR ...

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

    38. INTERIOR VIEW TO THE NORTHWEST OF THE SECOND FLOOR CORRIDOR ON THE SOUTH SIDE OF THE DISASSEMBLY BAY. VIEWING AND WORK STATIONS ARE ALONG THE NORTH WALL OF THE CORRIDOR. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  16. Lessons to be learned from rehabilitation of concrete structures in bleach plants in pulp and paper mills

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nixon, R.

    The deterioration of concrete structures due to chloride induced reinforcing steel corrosion such as in elevated concrete floor slabs, columns, and beams in bleach plants is a constant and growing problem within the pulp and paper industry. In general, the condition analysis methods used for assessing the extent of bleach plant concrete degradation include physical testing of drilled concrete core samples, chloride ion concentration testing, half-cell potential measurements, and physical sounding of concrete surfaces, i.e. chain drag for topside surfaces and hammer sounding of soffit surfaces. While this paper does not promote any vastly different evaluative methods, it does sharemore » learnings relative to interpreting the data provided by these typical test methods. It further offers some recommendations on how to improve the use of these typical evaluation techniques and offers some other test methods which should be considered as valuable additions for such evaluations. One of the most common methods which has been used in the past for large scale bleach plant concrete restoration has been the application of site dry mixed shotcrete for rebuilding the soffits of floor slabs and the faces of columns and beams. More often than not, bulk mixed dry shotcrete repairs have not been cost-effective because they prematurely failed due to excessive hydration related shrinkage cracking, lack of sufficient adhesion to the parent concrete substrate or other problems related to poor durability or construction practice.« less

  17. 5. MOTOR/WINCH DRUM ASSEMBLY FOR OXYGEN LANCE HOISTING RIG ON ...

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

    5. MOTOR/WINCH DRUM ASSEMBLY FOR OXYGEN LANCE HOISTING RIG ON THE WEIGHING FLOOR OF THE FURNACE AISLE IN THE BOP SHOP LOOKING SOUTHEAST. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  18. 17. INTERIOR VIEW TO THE EAST OF ROOM 215, A ...

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

    17. INTERIOR VIEW TO THE EAST OF ROOM 215, A SECOND FLOOR OFFICE ABOVE ROOM 137 IN THE COLD ASSEMBLY AREA. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  19. 118. JOB NO. 1347M, SHEET 2, 1930/1931, ADDITION FOR PRESSED ...

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

    118. JOB NO. 1347-M, SHEET 2, 1930/1931, ADDITION FOR PRESSED STEEL DEPARTMENT FOR FORD MOTOR COMPANY; FIRST FLOOR PLAN - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  20. 16. LOOKING WEST AT THE MOTOR DRIVE ASSEMBLY FOR THE ...

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

    16. LOOKING WEST AT THE MOTOR DRIVE ASSEMBLY FOR THE BASIC OXYGEN FURNACE No. 2 ON THE OPERATING FLOOR OF THE FURNACE AISLE IN THE BOP SHOP. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  1. Rules for Adaptive Learning and Assistance on the Shop Floor

    ERIC Educational Resources Information Center

    Ullrich, Carsten

    2016-01-01

    Today's shop floor, the area of a factory where operatives assemble products, is a complex and demanding work environment. The employed and produced technology becomes ever more complex, and employees are responsible for an increasing amount of tasks. As a consequence, the employee is under constant pressure to solve problems occurring on the shop…

  2. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marc Hoeschele; Eric Lee

    Concrete slabs represent the primary foundation type in residential buildings in the fast-growing markets throughout the southern and southwestern United States. Nearly 75% of the 2005 U.S. population growth occurred in these southern tier states. Virtually all of these homes have uninsulated slab perimeters that transfer a small, but steady, flow of heat from conditioned space to outdoors during the heating season. It is estimated that new home foundations constructed each year add 0.016 quads annually to U.S. national energy consumption; we project that roughly one quarter of this amount can be attributed to heat loss through the slab edgemore » and the remaining three quarters to deep ground transfers, depending upon climate. With rising concern over national energy use and the impact of greenhouse gas emissions, it is becoming increasingly imperative that all cost-effective efforts to improve building energy efficiency be implemented. Unlike other building envelope components that have experienced efficiency improvements over the years, slab edge heat loss has largely been overlooked. From our vantage point, a marketable slab edge insulation system would offer significant benefits to homeowners, builders, and the society as a whole. Conventional slab forming involves the process of digging foundation trenches and setting forms prior to the concrete pour. Conventional wood form boards (usually 2 x 10's) are supported by vertical stakes on the outer form board surface, and by supporting 'kickers' driven diagonally from the top of the form board into soil outside the trench. Typically, 2 x 10's can be used only twice before they become waste material, contributing to an additional 400 pounds of construction waste per house. Removal of the form boards and stakes also requires a follow-up trip to the jobsite by the concrete subcontractor and handling (storage/disposal) of the used boards. In the rare cases where the slab is insulated (typically custom homes with radiant floor heating), the most practical insulation strategy is to secure rigid foam insulation, such as Dow Styrofoam{trademark}, to the inside of the wooden slab edge forms. An alternative is to clad insulation to the perimeter of the slab after the slab has been poured and cured. In either case, the foam must have a 'termite strip' that prevents termites from creating hidden tunnels through or behind the foam on their way to the wall framing above. Frequently this termite strip is a piece of sheet metal that must be fabricated for each project. The above-grade portion of the insulation also needs to be coated for appearance and to prevent damage from construction and UV degradation. All these steps add time, complexity, and expense to the insulating process.« less

  3. Geometrical Optics of Dense Aerosols

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hay, Michael J.; Valeo, Ernest J.; Fisch, Nathaniel J.

    2013-04-24

    Assembling a free-standing, sharp-edged slab of homogeneous material that is much denser than gas, but much more rare ed than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed fi eld, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the nite particle density reduces the eff ective Stokes number of the flow, amore » critical result for controlled focusing. __________________________________________________« less

  4. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘D’, 2ND FLOOR PLAN, ARCHITECTURAL. Sheet 38 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  5. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘D’, MAIN FLOOR PLAN, ARCHITECTURAL. Sheet 39 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  6. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘E’, MAIN FLOOR PLAN, ARCHITECTURAL. Sheet 23 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  7. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘D’, 3RD FLOOR PLAN, ARCHITECTURAL. Sheet 37 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  8. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘B’, MAIN FLOOR PLAN, ARCHITECTURAL. Sheet 30 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  9. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘C’, 2ND FLOOR PLAN, ARCHITECTURAL. Sheet 15 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  10. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘C’, MAIN FLOOR PLAN, ARCHITECTURAL. Sheet 16 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  11. Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. ...

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

    Photocopy of drawing. VEHICLE ASSEMBLY BUILDING MODIFICATIONS. NASA John F. Kennedy Space Center, Florida. File Number 79K05424, Seelye Stevenson Value & Knecht, March 1975. HIGH BAY 3, EXTENSIBLE WORK PLATFORM ‘B’, 2ND FLOOR PLAN, ARCHITECTURAL. Sheet 29 of 207 - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  12. 36. INTERIOR VIEW TO THE NORTHWEST OF THE SECOND FLOOR ...

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

    36. INTERIOR VIEW TO THE NORTHWEST OF THE SECOND FLOOR CORRIDOR ON THE EAST SIDE OF THE DISASSEMBLY BAY. A VIEWING AND WORK STATION AND ENTRANCE TO THE CONTROL ROOM ARE ON THE WEST SIDE OF THE CORRIDOR. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  13. 49 CFR 393.104 - What standards must cargo securement devices and systems meet in order to satisfy the...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... working load limit. (c) Vehicle structures and anchor points. Vehicle structures, floors, walls, decks... tiedown assemblies. Tiedown assemblies (including chains, wire rope, steel strapping, synthetic webbing... . . . Must conform to . . . (1) Steel strapping 1 2 Standard Specification for Strapping, Flat Steel and...

  14. 49 CFR 393.104 - What standards must cargo securement devices and systems meet in order to satisfy the...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... working load limit. (c) Vehicle structures and anchor points. Vehicle structures, floors, walls, decks... tiedown assemblies. Tiedown assemblies (including chains, wire rope, steel strapping, synthetic webbing... . . . Must conform to . . . (1) Steel strapping 1,2 Standard Specification for Strapping, Flat Steel and...

  15. 49 CFR 393.104 - What standards must cargo securement devices and systems meet in order to satisfy the...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... working load limit. (c) Vehicle structures and anchor points. Vehicle structures, floors, walls, decks... tiedown assemblies. Tiedown assemblies (including chains, wire rope, steel strapping, synthetic webbing... . . . Must conform to . . . (1) Steel strapping 1 2 Standard Specification for Strapping, Flat Steel and...

  16. 57. Neg. No. F161D, Mar 18, 1933, INTERIORPRESSED STEEL AND ...

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

    57. Neg. No. F-161D, Mar 18, 1933, INTERIOR-PRESSED STEEL AND WAREHOUSE BUILDINGS, 1ST FLOOR, SHOWING DAMAGE TO FREIGHT ELEVATOR SHAFT FROM EARTHQUAKE - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  17. Tomotectonic constraints on the assembly of Jura-cretaceous western North America, and a southwest Pacific analogue

    NASA Astrophysics Data System (ADS)

    Mihalynuk, M. G.; Sigloch, K.

    2017-12-01

    We integrate the topology of subducted slabs imaged beneath North America by seismic tomography, with surviving Atlantic and Pacific seafloor isochrons, to reveal evolving arc, trench, and plate geometries back to the breakup of Pangea. Land geological evidence is used to independently validate or reject the inferred paleogeographies. Such tomotectonic analysis offers a methodology for resolving fundamental questions about the assembly of North America. For example: When, where and how did superterranes collide with North America? Did an Andean-type margin exist along western North America for all times between Cenozoic Cascade arc formation and the Jurassic, when an arc was rooted in continental crust of southwest USA? Deep mantle and seafloor isochron evidence show that TWO massive arc complexes originated in the seas west of Pangea as it started to fragment ( 190-170 Ma), a time when eastward subduction beneath the continental margin arc was shutting down. Most recognizable, and 2000-4000 km off the west coast of Pangea, is a >10,000 km long, east-pointing chevron of slab walls in the lower mantle, with its apex near present-day Nova Scotia. Formerly considered Farallon slab, its location and geometry are not consistent with continent-hugging, Jurassic to Recent Farallon subduction. Instead, a second massive and more westerly slab wall, 4000 - 6000 km west of Pangea, must have intercepted and consumed all northern Farallon lithosphere, and continues to do so beneath the Cascades. Both slabs initiated intraoceanic. Their arcs did not contribute to an Andean-style margin until they were diachronously overridden by North America, beginning 155 Ma. Implied is a continent-spanning suture between these two arc complexes and North America. Land geological evidence of this suture is an Alaska to Mexico track of at least 12 Jura-Cretaceous basins that collapsed between the Insular and Intermontane microcontinents, over half of which contain relicts of mantle. A conceptual framework for the Early Cretaceous North American suturing is found in the southwest Pacific. An analogous arrangement of plates and diachronous suture is forming today as Australia overrides arcs to its north.

  18. Crystal structure of BaMn2(AsO4)2 containing discrete [Mn4O18]28- units.

    PubMed

    Alcantar, Salvador; Ledbetter, Hollis R; Ranmohotti, Kulugammana G S

    2017-12-01

    In our attempt to search for mixed alkaline-earth and transition metal arsenates, the title compound, barium dimanganese(II) bis-(arsenate), has been synthesized by employing a high-temperature RbCl flux. The crystal structure of BaMn 2 (AsO 4 ) 2 is made up of MnO 6 octa-hedra and AsO 4 tetra-hedra assembled by sharing corners and edges into infinite slabs with composition [Mn 2 (AsO 4 ) 2 ] 2- that extend parallel to the ab plane. The barium cations reside between parallel slabs maintaining the inter-slab connectivity through coordination to eight oxygen anions. The layered anionic framework comprises weakly inter-acting [Mn 4 O 18 ] 28- tetra-meric units. In each tetra-mer, the manganese(II) cations are in a planar arrangement related by a center of inversion. Within the slabs, the tetra-meric units are separated from each other by 6.614 (2) Å (Mn⋯Mn distances). The title compound has isostructural analogues amongst synthetic Sr M 2 ( X O 4 ) 2 compounds with M = Ni, Co, and X = As, P.

  19. Combined Li-He isotopes in Iceland and Jan Mayen basalts and constraints on the nature of the North Atlantic mantle

    NASA Astrophysics Data System (ADS)

    Magna, T.; Wiechert, U.; Stuart, F. M.; Halliday, A. N.; Harrison, D.

    2011-02-01

    Lithium (Li) isotopes are thought to provide a powerful proxy for the recycling of crustal material, affected by low temperature alteration, through the mantle. We present Li isotope compositions for basaltic volcanic rocks from Hengill, Iceland, and Jan Mayen in order to examine possible links between ocean island volcanism and recycled oceanic crust and to address recent suggestions that mantle 3He/ 4He is also related to recycling of ancient slabs. Basaltic glasses spanning a range of chemical enrichment from the Hengill fissure system define an inverse correlation between δ 7Li (3.8-6.9‰) and 3He/ 4He (12-20 RA). The high- 3He/ 4He basalts have low δ 18O as well as excess Eu and high Nb/U, but carry no Li isotope evidence of being the product of recycling of altered slab or wedge material. In fact, there is no clear correlation between Li or He isotopes on the one hand and any of the other fingerprints of recycled slab components. The low- 3He/ 4He samples do have elevated Nb/U, Sr/Nd, positive Eu anomalies and high δ 7Li (˜6.9‰), providing evidence of a cumulate-enriched source that could be part of an ancient altered ocean floor slab. Basalts from Jan Mayen are characterized by large degrees of enrichment in incompatible trace elements typical of EM-like basalts but have homogeneous δ 7Li typical of depleted mantle (3.9-4.7‰) providing evidence for a third mantle source in the North Atlantic. It appears that oceanic basalts can display a wide range in isotope and trace element compositions associated with recycled components whilst exhibiting no sign of modern surface-altered slab or wedge material from the Li isotope composition.

  20. 32. INTERIOR VIEW TO THE NORTH OF THE FIRST FLOOR ...

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

    32. INTERIOR VIEW TO THE NORTH OF THE FIRST FLOOR EAST CORRIDOR AND VIEWING GALLERY TO THE DISASSEMBLY BAY. A VIEWING AND WORK STATION FOR THE EAST SIDE OF THE UPPER LEVEL OF THE DISASSEMBLY BAY IS ON THE WEST SIDE OF THE CORRIDOR. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  1. Slab photonic crystals with dimer colloid bases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Riley, Erin K.; Liddell Watson, Chekesha M., E-mail: cliddell@ccmr.cornell.edu

    2014-06-14

    The photonic band gap properties for centered rectangular monolayers of asymmetric dimers are reported. Colloids in suspension have been organized into the phase under confinement. The theoretical model is inspired by the range of asymmetric dimers synthesized via seeded emulsion polymerization and explores, in particular, the band structures as a function of degree of lobe symmetry and degree of lobe fusion. These parameters are varied incrementally from spheres to lobe-tangent dimers over morphologies yielding physically realizable particles. The work addresses the relative scarcity of theoretical studies on photonic crystal slabs with vertical variation that is consistent with colloidal self-assembly. Odd,more » even and polarization independent gaps in the guided modes are determined for direct slab structures. A wide range of lobe symmetry and degree of lobe fusion combinations having Brillouin zones with moderate to high isotropy support gaps between odd mode band indices 3-4 and even mode band indices 1-2 and 2-3.« less

  2. Self-Assembled Layered Supercell Structure of Bi2AlMnO6 with Strong Room-Temperature Multiferroic Properties.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Leigang; Boullay, Philippe; Lu, Ping

    2017-02-01

    Room-temperature (RT) multiferroics, possessing ferroelectricity and ferromagnetism simultaneously at RT, hold great promise in miniaturized devices including sensors, actuators, transducers, and multi-state memories. In this work, we report a novel 2D layered RT multiferroic system with self-assembled layered supercell structure consisting of two mismatch-layered sub-lattices of [Bi 3O 3+δ] and [MO 2] 1.84 (M=Al/Mn, simply named as BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made of a three-layer-thick Bi-O slab and a one-layer-thick Al/Mn-O octahedra slab along the out-of-plane direction. Strong room-temperature multiferroic responses, e.g., ferromagnetic and ferroelectric properties, have been demonstrated and attributed to the highlymore » anisotropic 2D nature of the non-ferromagnetic and ferromagnetic sublattices which are highly mismatched. The work demonstrates an alternative design approach for new 2D layered oxide materials that hold promises as single-phase multiferroics, 2D oxides with tunable bandgaps, and beyond.« less

  3. Terminator assembly for a floating structure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chiu, H.; Hall, J.E.

    1987-10-20

    A terminator assembly is described for use in mooring a floating surface to the floor of a body of water. The floating structure has has an upper support and a lower support, comprising: a hawsepipe extending downwardly from adjacent the upper support and supported by the lower support, a tension member extending downwardly from adjacent the upper support through the hawsepipe and the lower support. The tension member has a lower end adapted for connection to the floor of the body of water. Locking means connected to an upper portion of the tension member for maintaining the tension member inmore » tension by acting upon an upper portion of the hawsepipe without transferring primary tension load forces to the upper support.« less

  4. Asphalt Volcanism and Chemosynthetic Life in the Campeche Knolls, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    MacDonald, I. R.; Bohrmann, G.; Escobar, E.; Abegg, F.; Blanchon, P.; Blinova, V.; Brückmann, W.; Drews, M.; Eisenhauer, A.; Han, X.; Heeschen, K.; Meier, F.; Mortera, C.; Naehr, T.; Orcutt, B.; Bernard, B.; Brooks, J.; de Faragó, M.

    2004-05-01

    In the Campeche Knolls, in the southern Gulf of Mexico, lava-like flows of solidified asphalt cover more than 1 square kilometer of the rim of a dissected salt dome at a depth of 3000 meters below sea level. Chemosynthetic tubeworms and bivalves colonize the sea floor near the asphalt, which chilled and contracted after discharge. The site also includes oil seeps, gas hydrate deposits, locally anoxic sediments, and slabs of authigenic carbonate. Asphalt volcanism creates a habitat for chemosynthetic life that may be widespread at great depth in the Gulf of Mexico.

  5. 32. View of relay assembly group and interconnecting group electronic ...

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

    32. View of relay assembly group and interconnecting group electronic modules located on second floor of transmitter building no. 102 in MIP area. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  6. DETAIL VIEW ON THE MAIN ASSEMBLY LEVEL OF A LADDER ...

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

    DETAIL VIEW ON THE MAIN ASSEMBLY LEVEL OF A LADDER TO THE CATWALK AT COLUMN LINE AA-28 SHOWING VERTICAL MECHANICAL DUCT, RETURN AIR FLOOR GRILLE, STEEL INDUSTRIAL SASH WINDOWS AND CROSS BRACING OF SOUTH WALL. - Offutt Air Force Base, Glenn L. Martin-Nebraska Bomber Plant, Building D, Peacekeeper Drive, Bellevue, Sarpy County, NE

  7. Measurements and analysis of leakage neutron spectra from multiple-slab sample assemblies comprising W,U,C, and CH2 with D-T neutron irradiation.

    PubMed

    Luo, F; Han, R; Chen, Z; Nie, Y; Sun, Q; Shi, F; Zhang, S; Tian, G; Song, L; Ruan, X; Ye, M Y

    2018-07-01

    The accelerator driven subcritical system (ADS) is regarded as a safe and clean nuclear power system, which can be used for the transmutation of nuclear waste and the breeding of nuclear fuel. In this study, in order to validate nuclear data and the neutron transportation performance of the materials related to ADS, we measured the leakage neutron spectra from multiple-slab sample assemblies using 14.8 MeV D-T neutrons. Two types of assemblies comprising A-1 (W+U+C+CH 2 ) and A-2 (U+C+CH 2 ) were both built up gradually starting with the first wall. The measured spectra were compared with those calculated using the Monte Carlo code neutron transport coed (MCNP)-4C. A comparison of the results showed that the experimental leakage neutron spectra for both A-1 or A-2 were reproduced well by the three evaluated nuclear data libraries with discrepancies of less than 15% (A-1) and 12% (A-2), except when below 3 MeV. For 2-cm and 5-cm uranium samples, the CENDL-3.1 calculations exhibited large discrepancies in the energy range of 2-8 MeV and above 13 MeV. Thus, the CENDL-3.1 library for uranium should be reevaluated, especially around this energy range. It was significant that the leakage neuron spectra changed clearly when the latest material layer was added during the building of assemblies A-1 and A-2. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. 40. INTERIOR VIEW TO THE SOUTHEAST OF ROOM 302, A ...

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

    40. INTERIOR VIEW TO THE SOUTHEAST OF ROOM 302, A SMALL ISOLATED OFFICE ON THE THIRD FLOOR ON THE EAST SIDE OF THE DISASSEMBLY BAY. A METAL SPIRAL STAIRCASE IS IN THE SOUTHEAST CORNER AND HATCHWAYS ARE IN THE CEILING AND FLOOR TOWARD THE EAST SIDE OF THE ROOM. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  9. Research on Crack Formation in Gypsum Partitions with Doorway by Means of FEM and Fracture Mechanics

    NASA Astrophysics Data System (ADS)

    Kania, Tomasz; Stawiski, Bohdan

    2017-10-01

    Cracking damage in non-loadbearing internal partition walls is a serious problem that frequently occurs in new buildings within the short term after putting them into service or even before completion of construction. Damage in partition walls is sometimes so great that they cannot be accepted by their occupiers. This problem was illustrated by the example of damage in a gypsum partition wall with doorway attributed to deflection of the slabs beneath and above it. In searching for the deflection which causes damage in masonry walls, fracture mechanics applied to the Finite Element Method (FEM) have been used. For a description of gypsum behaviour, the smeared cracking material model has been selected, where stresses are transferred across the narrowly opened crack until its width reaches the ultimate value. Cracks in the Finite Element models overlapped the real damage observed in the buildings. In order to avoid cracks under the deflection of large floor slabs, the model of a wall with reinforcement in the doorstep zone and a 40 mm thick elastic junction between the partition and ceiling has been analysed.

  10. General view of the Space Shuttle Main Engine (SSME) assembly ...

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

    General view of the Space Shuttle Main Engine (SSME) assembly with the expansion nozzle removed and resting on a cushioned mat on the floor of the SSME Processing Facility. The most prominent features in this view are the Low-Pressure Fuel Turbopump (LPFTP) on the upper left of the engine assembly, the LPFTP Discharge Duct looping around the assembly, the Gimbal Bearing on the top center of the assembly, the Electrical Interface Panel sits just below the Gimbal Bearing and the Low-Pressure Oxidizer Turbopump is mounted on the top right of the engine assembly in this view. - Space Transportation System, Space Shuttle Main Engine, Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  11. Advanced techniques for repair of irradiated PWR fuel assemblies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Knaab, H.; Westphal, M.

    Kraftwerk union has recently designed and built a portable repair unit for use in nuclear power plants for repair of defective fuel assemblies where space limitations do not allow permanent installation of repair equipment. This new equipment is designed to be easily disassembled and decontaminated. The main component of the equipment is the fuel assembly reconstitution unit (FARU) which is placed on the floor of the spent fuel pool. The use of the FARU is described in the paper.

  12. 3. Photograph of a line drawing. SHEET 3, FLOOR PLAN, ...

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

    3. Photograph of a line drawing. SHEET 3, FLOOR PLAN, DETAILS OF S EAST AND S WEST CORNERS, TYPICAL DETAIL AT COLUMN U-49 and U-25, TYPICAL SECTION THRU R. R. TRACK IN S WEST CORNER, SECTION THRU PIPE PIT AT COLUMN #P-1; 9-16-1940. Assembly Building for Tank Plant for the Chrysler Corporation, Macomb County, Michigan. Delineator: H. C. B. - Detroit Arsenal, 6501 East Eleven Mile Road, Warren, Macomb County, MI

  13. Rehabilitation of a Distressed Single Storied Building Founded on Expansive Soil: A Case Study

    NASA Astrophysics Data System (ADS)

    Pakrashi, Somdev

    2017-12-01

    A single storied building was constructed on strip foundation system—on a subsoil, with high expansivity, without taking necessary precautions and it suffered extensive cracks and damages in roof slab, beams, columns and brick walls, subsidence /upheavals in floors etc. within 2/3 years of its construction and consequently it had to be abandoned. The study examines the reasons for the severe damages, cracks etc. and also suggests remediation by ground improvement and other necessary measures that were actually taken up, to rehabilitate the highly distressed and abandoned building within a reasonably short period of time—at a reasonable cost.

  14. Odua Weston Jambi Hotel’s Structural Building Design with Prestressed Concrete Slab System Approach

    NASA Astrophysics Data System (ADS)

    Bayuaji, R.; Darmawan, M. S.; Rofiq, M. A.; Santoso, S. E.; Hardiyanto, E.

    2017-11-01

    Odua Weston Jambi Hotel is an eight-floor hotel and located in a prone to earth-quake area. This building used conventional concrete to its structural beam and column. This research’s purpose was to maximize the second-floor’s function by modifing its architectural design. Special Moment Resisting Frame System (SMRFS) approach was used in the structural design, referred to SNI 03-2847-2013 dan SNI 1726-2012 and to compensate the needs of a spacious hall without any column in the centre of the hall, so therefore, prestressed concrete plate is used to solve this problem.

  15. Analyzing genetic diversity in conifers...isozyme resolution by starch gel electrophoresis

    Treesearch

    M. Thompson Conkle

    1972-01-01

    Enzymes in forest tree materials can be resolved by starch gel electrophoresis. A gel slab is prepared in a mold assembled from glass and plastic. Wicks containing an aqueous extract of macerated plant material are inserted in the gel and processed. The gel is sliced, stained, examined, and photographed. Isozyme bands produced by differential migration of enzymes...

  16. 133. Photocopy of photograph, 1915 (Chrysler) MAIN BUILDING #1, SECOND ...

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

    133. Photocopy of photograph, 1915 (Chrysler) MAIN BUILDING #1, SECOND FLOOR CHASSIS ASSEMBLY LINE, VIEW SOUTH, 1980 - Dodge Brothers Motor Car Company Plant, Between Joseph Campau & Conant Avenues, Hamtramck, MI

  17. MM&T for Linear Resonant Cooler. Volume 1

    DTIC Science & Technology

    1988-02-16

    Tesla *Magnet Material Samarium Cobalt Radially Magnetized Inner Diameter = 1.25" Length = 0.79" Coil Assembly Number of Turns/Section = 90 Outside...Diameter = 1.22" Inside Diameter = 0.86" Inner Iron Material 2 V Permendur Inside Diameter = 0.38" Length 1.84" Design Max. Flux Density = 2.4 Tesla 0 3-12...suspended with rubber bands 60 inches above the floor of the semi -anechoic room. A six foot square piece of 2 inch thick foam was centered on the floor

  18. Rail assembly for use in a radioactive environment

    DOEpatents

    Watts, Ralph E.

    1989-01-01

    An improved rail assembly and method of construction thereof is disclosed herein that is particularly adapted for use with a crane trolley in a hot cell environment which is exposed to airborne and liquidborne radioactive contaminants. The rail assembly is generally comprised of a support wall having an elongated, rail-housing recess having a floor, side wall and ceiling. The floor of the recess is defined at least in part by the load-bearing surface of a rail, and is substantially flat, level and crevice-free to facilitate the drainage of liquids out of the recess. The ceiling of the recess overhangs and thereby captures trolley wheels within the recess to prevent them from becoming dislodged from the recess during a seismic disturbance. Finally, the interior of the recess includes a power track having a slot for receiving a sliding electrical connector from the crane trolley. The power track is mounted in an upper corner of the recess with its connector-receiving groove oriented downwardly to facilitate the drainage of liquidborne contaminants and to discourage the collection of airborne contaminants within the track.

  19. Tomographic images of subducted oceans matched to the accretionary records of orogens - Case study of North America and relevance to Central Asia

    NASA Astrophysics Data System (ADS)

    Sigloch, Karin; Mihalynuk, Mitchell G.; Hosseini, Kasra

    2016-04-01

    Accretionary orogens are the surface record of subduction on the 100-million-year timescale; they aggregate buoyant crustal welts that resisted subduction. The other record of subduction is found in the deep subsurface: oceanic lithosphere preserved in the mantle that records ocean basin closure between successive generations of arcs. Seismic tomography maps out these crumpled paleo-oceans down to the core-mantle boundary, where slab accumulates. One such accumulation of enormous scale is under Eastern Asia, recording the assembly of the Central Asian Orogenic Belt (CAOB). Deep CAOB slab has hardly been explored because tomographic image resolution in the lowermost mantle is limited, but this is rapidly improving. We present new images of the CAOB slabs from our P-wave tomography that includes core-diffracted waves as a technical novelty. The previous slab blur sharpens into the type of elongated geometries expected to trace paleo-trench lines. Since the North American Cordillera is younger than the CAOB (mostly <200 m.y. versus ~650-250 m.y.), its slabs have descended only to mid-mantle depths (<2000 km), where tomographic resolution is much better. Hence we can make a detailed, spatiotemporal match between 3-D slab geometries and the accretion history of the Cordillera - a blueprint for continental-scale investigations in other accretionary orogens, including what may become possible for the CAOB. Lower-mantle slabs beneath North America reveal evolving configurations of arc-trench positions back to the breakup of Pangea. These can be combined with quantitative plate reconstructions to show where and when the westward-drifting continent overrode pre-existing, intra-oceanic subduction zones, and accreted their associated arcs and basement terranes in Jurassic and Cretaceous times. Tectonic predictions from this "tomographic time machine" can be checked against the geological record. To demonstrate, we propose a resolution to the longstanding debate of how and when western North America accreted the microcontinental Insular Superterrane (Wrangellia, Alexander, Peninsular) and its southern relative, the Guerrero Superterrane. Mantle structure supports an unconventional paleogeography whereby these Mesozoic arcs had grown in a long-lived archipelago located 2000-4000 km west of Pangean North America, its paleo-trench lines marked by massive, steep slab walls >10,000 km long. North America converged on the two microcontinents by westward subduction of two intervening basins (which we name Mezcalera and Angayucham oceans), culminating in diachronous suturing between ~150 Ma and ~50 Ma. Hence geophysical subsurface evidence negates the widely accepted "Andean-style" model of Farallon-beneath-continent subduction since at least 180 Ma, and supports a Jura-Cretaceous paleogeography closer to today's Southwestern Pacific, or to the Paleozoic CAOB. Though advocated since the 1970's by a minority of geologists, this scenario had not gained wide acceptance due to a record obscured by overprinting, margin-parallel translation, and oroclinal bending. The new subsurface evidence provides specific indications where to seek the decisive Mezcalera-Angayucham suture. The suture is evident in a trail of collapsed Jura-Cretaceous basin relics that run the length of the Cordillera. Reference: Sigloch, K., & Mihalynuk, M. G. (2013). Intra-oceanic subduction shaped the assembly of Cordilleran North America. Nature, 496(7443), 50-56. doi:10.1038/nature12019

  20. 7 CFR 58.146 - Cleaning and sanitizing treatment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... seal assemblies shall be removable on all agitators, pumps, and vats and shall be inspected at regular... above the floor in clean, dry locations and in a self draining position on racks constructed of...

  1. Deep earthquakes beneath the Fiji Basin, SW Pacific: Earth's most intense deep seismicity in stagnant slabs

    USGS Publications Warehouse

    Okal, E.A.; Kirby, S.H.

    1998-01-01

    Previous work has suggested that many of the deep earthquakes beneath the Fiji Basin occur in slab material that has been detached and foundered to the bottom of the transition zone or has been laid down by trench migration in a similar recumbent position. Since nowhere else in the Earth do so many earthquakes occur in slabs stagnated in the transition zone, these earthquakes merit closer study. Accordingly, we have assembled from historical and modern data a comprehensive catalogue of the relocated hypocenters and focal mechanisms of well-located deep events in the geographic area between the bottoms of the main Vanuatu and Tonga Wadati-Benioff zones. Two regions of deep seismogenesis are recognized there: (i) 163 deep shocks have occurred north of 15??S in the Vityaz Group from 1949 to 1996. These seismological observations and the absence of other features characteristic of active subduction suggest that the Vityaz group represents deep failure in a detached slab that has foundered to a horizontal orientation near the bottom of the transition zone. (ii) Another group of nearly 50 'outboard' deep shocks occur between about 450 and 660 km depth, west of the complexly buckled and offset western edge of the Tonga Wadati-Benioff zone. Their geometry is in the form of two or possibly three small-circle arcs that roughly parallel the inferred motion of Tonga trench migration. Earthquakes in the southernmost of these arcs occur in a recumbent high-seismic-wavespeed slab anomaly that connects both to the main inclined Tonga anomaly to the east and a lower mantle anomaly to the west [Van der Hilst, R., 1995. Complex morphology of subducted lithosphere in the mantle beneath the Tonga trench. Nature, Vol. 374, pp. 154-157.]. Both groups show complexity in their focal mechanisms. The major question raised by these observations is the cause of this apparent temporary arrest in the descent of the Tonga slab into the lower mantle. We approach these questions by considering the effects of buoyant metastable peridotite in cold slab material that was detached and rapidly foundered, or was buckled, segmented and laid out in the transition zone.

  2. Fluid-mediated redox transfer in subduction zones: Measuring the intrinsic fO2 of slab fluids in the lab

    NASA Astrophysics Data System (ADS)

    Iacovino, K.; Till, C. B.

    2017-12-01

    It is widely observed that arc magmas are the most oxidized magmas on Earth. One frequently cited explanation calls on the flux of aqueous fluid from the highly oxidized down-going slab to catalyze sub-arc mantle melting and impose a highly oxidized redox signature on the mantle wedge. Fluid inclusions from sub-arc mantle xenoliths provide evidence that "slab fluids" may be highly oxidizing (fO2 QFM+1.5; Brandon & Draper, 1996; Frost and Ballhaus, 1998), but for decades, determination of the precise reactive mechanism potentially responsible for the transfer of O2 from slab to mantle has been elusive. Pure H2O has been shown to have insufficient oxidizing capacity to affect mantle redox, but H2O-rich fluids may facilitate the mobilization of Fe3+ or other multivalent cations and/or O2 transfer via the reduction of sulfate, particularly if such fluids are hypersaline. Here we present the first results from experiments designed to investigate fluid-mediated element transfer, including redox reactions, at the slab-mantle interface. These data include the first direct measurements of the intrinsic oxygen fugacity of fluids released during slab dehydration using sliding binary alloy redox sensors. Experiments were performed on natural Fe3+-bearing antigorite serpentinite at 1-2 GPa and 800°C in a piston cylinder at Arizona State University, analogous to conditions in a subducting slab and sufficient to cause the breakdown of starting material into forsteritic olivine, Mg-rich clinopyroxene, magnetite, and aqueous fluid. Experimental time series allow for the detection of (and correction for) any buffering effect on the sample by the experimental assembly. Initial results indicate that the dehydration of sulfur-free antigorite serpentinite can generate fluids with fO2 several orders of magnitude above that of MORB mantle and similar to those observed in natural sub-arc fluid inclusions. Careful measurements of the chemistry of fluid and solid run products will elucidate the redox exchange reaction responsible for these fluid characteristics. These data suggest the dehydration of slab serpentine and the derivative fluid may play an important role in controlling the redox of arc magmas and the sub-arc mantle.

  3. A Review on Forearc Ophiolite Obduction, Adakite-Like Generation, and Slab Window Development at the Chile Triple Junction Area: Uniformitarian Framework for Spreading-Ridge Subduction

    NASA Astrophysics Data System (ADS)

    Bourgois, Jacques; Lagabrielle, Yves; Martin, Hervé; Dyment, Jérôme; Frutos, Jose; Cisternas, Maria Eugenia

    2016-10-01

    This paper aggregates the main basic data acquired along the Chile Triple Junction (CTJ) area (45°-48°S), where an active spreading center is presently subducting beneath the Andean continental margin. Updated sea-floor kinematics associated with a comprehensive review of geologic, geochemical, and geophysical data provide new constraints on the geodynamics of this puzzling area. We discuss: (1) the emplacement mode for the Pleistocene Taitao Ridge and the Pliocene Taitao Peninsula ophiolite bodies. (2) The occurrence of these ophiolitic complexes in association with five adakite-like plutonic and volcanic centers of similar ages at the same restricted locations. (3) The inferences from the co-occurrence of these sub-coeval rocks originating from the same subducting oceanic lithosphere evolving through drastically different temperature-pressure ( P- T) path: low-grade greenschist facies overprint and amphibolite-eclogite transition, respectively. (4) The evidences that document ridge-jump events and associated microplate individualization during subduction of the SCR1 and SCR-1 segments: the Chonos and Cabo Elena microplates, respectively. The ridge-jump process associated with the occurrence of several closely spaced transform faults entering subduction is controlling slab fragmentation, ophiolite emplacement, and adakite-like production and location in the CTJ area. Kinematic inconsistencies in the development of the Patagonia slab window document an 11- km westward jump for the SCR-1 spreading segment at ~6.5-to-6.8 Ma. The SCR-1 spreading center is relocated beneath the North Patagonia Icefield (NPI). We argue that the deep-seated difference in the dynamically sustained origin of the high reliefs of the North and South Patagonia Icefield (NPI and SPI) is asthenospheric convection and slab melting, respectively. The Chile Triple Junction area provides the basic constraints to define the basic signatures for spreading-ridge subduction beneath an Andean-type margin.

  4. Batch Scheduling for Hybrid Assembly Differentiation Flow Shop to Minimize Total Actual Flow Time

    NASA Astrophysics Data System (ADS)

    Maulidya, R.; Suprayogi; Wangsaputra, R.; Halim, A. H.

    2018-03-01

    A hybrid assembly differentiation flow shop is a three-stage flow shop consisting of Machining, Assembly and Differentiation Stages and producing different types of products. In the machining stage, parts are processed in batches on different (unrelated) machines. In the assembly stage, each part of the different parts is assembled into an assembly product. Finally, the assembled products will further be processed into different types of final products in the differentiation stage. In this paper, we develop a batch scheduling model for a hybrid assembly differentiation flow shop to minimize the total actual flow time defined as the total times part spent in the shop floor from the arrival times until its due date. We also proposed a heuristic algorithm for solving the problems. The proposed algorithm is tested using a set of hypothetic data. The solution shows that the algorithm can solve the problems effectively.

  5. Female Pelvic Floor Biomechanics: Bridging the Gap

    PubMed Central

    Easley, Deanna C.; Abramowitch, Steven D.; Moalli, Pamela A.

    2017-01-01

    Purpose of review The pelvic floor is a complex assembly of connective tissues and striated muscle that simultaneously counteract gravitational forces, inertial forces, and intraabdominal pressures while maintaining the position of the pelvic organs. In 30% of women, injury or failure of the pelvic floor results in pelvic organ prolapse (POP). Surgical treatments have high recurrence rates, due, in part, to a limited understanding of physiologic loading conditions. It is critical to apply biomechanics to help elucidate how altered loading conditions of the pelvis contribute to the development of pelvic organ prolapse and to define surgeries to restore normal support. Recent findings Evidence suggests the ewe is a potential animal model for studying vaginal properties and that uterosacral and cardinal ligaments experience significant creep, which may be affecting surgical outcomes. A new method of measuring ligament displacements in vivo was developed, and finite element models that simulate urethral support, pelvic floor dynamics, and the impact of episiotomies on the pelvic floor were studied. Summary This review highlights some contributions over the past year, including mechanical testing and the creation of models, which are used to understand pelvic floor changes with loading, and the impact of surgical procedures, to illustrate how biomechanics is being utilized. PMID:28267057

  6. 77 FR 5817 - Ocean Renewable Power Company, Tidal Energy Project, Cobscook Bay, ME

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-06

    ... ocean floor, used for generating electricity from tidal currents and is now providing the public the... impacts associated with installation of an underwater cable assembly to transfer electricity to a power...

  7. Commander Truly cleans ARS filters on middeck

    NASA Image and Video Library

    1983-09-05

    STS008-13-336 (5 Sept 1983) --- On middeck, Richard M. Truly, STS-8 commander, uses vacuum cleaner to remove debris from air revitalization system (ARS) filter assembly. Open panel on middeck floor is the ARS access panel.

  8. Radon exhalation from building materials for decorative use.

    PubMed

    Chen, Jing; Rahman, Naureen M; Abu Atiya, Ibrahim

    2010-04-01

    Long-term exposure to radon increases the risk of developing lung cancer. There is considerable public concern about radon exhalation from building materials and the contribution to indoor radon levels. To address this concern, radon exhalation rates were determined for 53 different samples of drywall, tile and granite available on the Canadian market for interior home decoration. The radon exhalation rates ranged from non-detectable to 312 Bq m(-2) d(-1). Slate tiles and granite slabs had relatively higher radon exhalation rates than other decorative materials, such as ceramic or porcelain tiles. The average radon exhalation rates were 30 Bq m(-2) d(-1) for slate tiles and 42 Bq m(-2) d(-1) for granite slabs of various types and origins. Analysis showed that even if an entire floor was covered with a material having a radon exhalation rate of 300 Bq m(-2) d(-1), it would contribute only 18 Bq m(-3) to a tightly sealed house with an air exchange rate of 0.3 per hour. Generally speaking, building materials used in home decoration make no significant contribution to indoor radon for a house with adequate air exchange. Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved.

  9. Piezoelectric energy harvester under parquet floor

    NASA Astrophysics Data System (ADS)

    Bischur, E.; Schwesinger, N.

    2011-03-01

    The design, fabrication and testing of piezoelectric energy harvesting modules for floors is described. These modules are used beneath a parquet floor to harvest the energy of people walking over it. The harvesting modules consist of monoaxial stretched PVDF-foils. Multilayer modules are built up as roller-type capacitors. The fabrication process of the harvesting modules is simple and very suitable for mass production. Due to the use of organic polymers, the modules are characterized by a great flexibility and the possibility to create them in almost any geometrical size. The energy yield was determined depending on the dynamic loading force, the thickness of piezoelectric active material, the size of the piezoelectric modules, their alignment in the walking direction and their position on the floor. An increase of the energy yield at higher loading forces and higher thicknesses of the modules was observed. It was possible to generate up to 2.1mWs of electric energy with dynamic loads of 70kg using a specific module design. Furthermore a test floor was assembled to determine the influence of the size, alignment and position of the modules on the energy yield.

  10. GENERAL VIEW OF NORTH VEHICLE ACCESS PLATFORMS, HB3, FACING NORTH ...

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

    GENERAL VIEW OF NORTH VEHICLE ACCESS PLATFORMS, HB-3, FACING NORTH TOWARDS FLOOR - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  11. Planar solar concentrator featuring alignment-free total-internal-reflection collectors and an innovative compound tracker.

    PubMed

    Teng, Tun-Chien; Lai, Wei-Che

    2014-12-15

    This study proposed a planar solar concentrator featuring alignment-free total-internal-reflection (TIR) collectors and an innovative compound tracker. The compound tracker, combining a mechanical single-axis tracker and scrollable prism sheets, can achieve a performance on a par with dual-axis tracking while reducing the cost of the tracking system and increasing its robustness. The alignment-free TIR collectors are assembled on the waveguide without requiring alignment, so the planar concentrator is relatively easily manufactured and markedly increases the feasibility for use in large concentrators. Further, the identical TIR collector is applicable to various-sized waveguide slab without requiring modification, which facilitates flexibility regarding the size of the waveguide slab. In the simulation model, the thickness of the slab was 2 mm, and its maximal length reached 6 m. With an average angular tolerance of ±0.6°, and after considering both the Fresnel loss and the angular spread of the sun, the simulation indicates that the waveguide concentrator of a 1000-mm length provides the optical efficiencies of 62-77% at the irradiance concentrations of 387-688, and the one of a 2000-mm length provides the optical efficiencies of 52-64.5% at the irradiance concentrations of 645-1148. Alternatively, if a 100-mm horizontally staggered waveguide slab is collocated with the alignment-free TIR collectors, the optical efficiency would be greatly improved up to 91.5% at an irradiance concentration of 1098 (C(geo) = 1200X).

  12. Patterned self-assembled monolayers of alkanethiols on copper nanomembranes by submerged laser ablation

    NASA Astrophysics Data System (ADS)

    Rhinow, Daniel; Hampp, Norbert A.

    2012-06-01

    Self-assembled monolayers (SAMs) of alkanethiols are major building blocks for nanotechnology. SAMs provide a functional interface between electrodes and biomolecules, which makes them attractive for biochip fabrication. Although gold has emerged as a standard, copper has several advantages, such as compatibility with semiconductors. However, as copper is easily oxidized in air, patterning SAMs on copper is a challenging task. In this work we demonstrate that submerged laser ablation (SLAB) is well-suited for this purpose, as thiols are exchanged in-situ, avoiding air exposition. Using different types of ω-substituted alkanethiols we show that alkanethiol SAMs on copper surfaces can be patterned using SLAB. The resulting patterns were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Both methods indicate that the intense laser beam promotes the exchange of thiols at the copper surface. Furthermore, we present a procedure for the production of free-standing copper nanomembranes, oxidation-protected by alkanethiol SAMs. Incubation of copper-coated mica in alkanethiol solutions leads to SAM formation on both surfaces of the copper film due to intercalation of the organic molecules. Corrosion-protected copper nanomembranes were floated onto water, transferred to electron microscopy grids, and subsequently analyzed by electron energy loss spectroscopy (EELS).

  13. Micro-shear bond strengths of adhesive resins to coronal dentin versus the floor of the pulp chamber.

    PubMed

    Toba, Shigemitsu; Veerapravati, Weeraporn; Shimada, Yasushi; Nikaido, Toru; Tagami, Junji

    2003-09-01

    To evaluate the micro-shear bond strengths to superficial coronal dentin and the floor of the pulp chamber using two dentin bonding systems and to compare the ultrastructure of the resin-dentin interface of the two regions. 30 non-carious molars were used to obtain 2 mm thick slabs of coronal dentin and dentin at the pulp chamber. The specimens in each region were divided into three sub-groups to be bonded as follows; Clearfil SE Bond was used according to the manufacturer's instructions, Single Bond was applied to either wet dentin (Blot dry Group) or air-dried dentin (Dry Group) after phosphoric acid etching. A resin composite cylinder 0.5 mm high and 0.75 mm in diameter formed using a vinyl tube was bonded to the dentin. Specimens were stored at 37 degrees C for 24 hours in water and then stressed in shear at a crosshead speed of 1 mm/minute. The data were analyzed with one-way ANOVA and Fisher's PLSD test at the 5% level of significance. In addition, the ultrastructure of cross-sectioned dentin surfaces, the conditioned dentin surface and the resin dentin interfaces were observed by SEM. The bond strengths of Clearfil SE Bond and the Single Bond Blot dry group were approximately 40 MPa in coronal dentin and 30 MPa in the dentin at the floor of the pulp chamber respectively. However, the bond strengths of Single Bond were significantly lower in the Dry condition (MPa) (P < 0.05). SEM observations revealed the thickness of the hybrid layer created by Clearfil SE Bond in coronal dentin and at the floor of the pulp chamber were less than 1.0 microm thick. For Single Bond, a 3-4 microm hybrid layer was created in coronal dentin, while a thinner hybrid layer was observed in the floor of the pulp chamber. Morphological and structural variations in dentin may have influenced the bond strengths of the bonding systems to the floor of the pulp chamber.

  14. Equilibrium polymerization models of re-entrant self-assembly

    NASA Astrophysics Data System (ADS)

    Dudowicz, Jacek; Douglas, Jack F.; Freed, Karl F.

    2009-04-01

    As is well known, liquid-liquid phase separation can occur either upon heating or cooling, corresponding to lower and upper critical solution phase boundaries, respectively. Likewise, self-assembly transitions from a monomeric state to an organized polymeric state can proceed either upon increasing or decreasing temperature, and the concentration dependent ordering temperature is correspondingly called the "floor" or "ceiling" temperature. Motivated by the fact that some phase separating systems exhibit closed loop phase boundaries with two critical points, the present paper analyzes self-assembly analogs of re-entrant phase separation, i.e., re-entrant self-assembly. In particular, re-entrant self-assembly transitions are demonstrated to arise in thermally activated equilibrium self-assembling systems, when thermal activation is more favorable than chain propagation, and in equilibrium self-assembly near an adsorbing boundary where strong competition exists between adsorption and self-assembly. Apparently, the competition between interactions or equilibria generally underlies re-entrant behavior in both liquid-liquid phase separation and self-assembly transitions.

  15. 3. JOB NO. 1347G, SHEET 1, 1930, OIL HOUSE; FORD ...

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

    3. JOB NO. 1347-G, SHEET 1, 1930, OIL HOUSE; FORD MOTOR COMPANY; FLOOR PLAN, ELEVATION, AND MISCELLANEOUS DETAIL - Ford Motor Company Long Beach Assembly Plant, Oil House, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  16. 4. JOB NO. 1347B, SHEET 1, 1927, OIL HOUSE; FORD ...

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

    4. JOB NO. 1347-B, SHEET 1, 1927, OIL HOUSE; FORD MOTOR COMPANY; FLOOR PLAN, ELEVATIONS AND SECTIONS - Ford Motor Company Long Beach Assembly Plant, Oil House, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  17. Three-dimensional Numerical Models of the Cocos-northern Nazca Slab Gap

    NASA Astrophysics Data System (ADS)

    Jadamec, M.; Fischer, K. M.

    2012-12-01

    In contrast to anisotropy beneath the middle of oceanic plates, seismic observations in subduction zones often indicate mantle flow patterns that are not easily explained by simple coupling of the subducting and overriding plates to the mantle. For example, in the Costa Rica-Nicaragua subduction zone local S shear wave splitting measurements combined with geochemical data indicate trench parallel flow in the mantle wedge with flow rates of 6.3-19 cm/yr, which is on order of or may be up to twice the subducting plate velocity. We construct geographically referenced high-resolution three-dimensional (3D) geodynamic models of the Cocos-northern Nazca subduction system to investigate what is driving the northwest directed, and apparently rapid, trench-parallel flow in the mantle wedge beneath Costa Rica-Nicaragua. We use the SlabGenerator code to construct a 3D plate configuration that is used as input to the community mantle convection code, CitcomCU. Models are run on over 400 CPUs on XSEDE, with a mesh resolution of up to 3 km at the plate boundary. Seismicity and seismic tomography delineate the shape and depth of the Cocos and northern Nazca slabs. The subducting plate thermal structure is based on a plate cooling model and ages from the seafloor age grid. Overriding plate thickness is constrained by the ages from the sea floor age grid where available and the depth to the lithosphere-asthenosphere boundary from the greatest negative gradient in absolute shear wave velocity. The geodynamic models test the relative controls of the change in the dip of the Cocos plate and the slab gap between the Cocos and northern Nazca plates in driving the mantle flow beneath Central America. The models also investigate the effect of a non-Newtonian rheology in dynamically generating a low viscosity mantle wedge and how this controls mantle flow rates. To what extent the Cocos-northern Nazca slab gap channelizes mantle flow between Central and South America has direct application to geochemical and geologic studies of the region. In addition, 3D geodynamic models of this kind can further test the hypothesis of rapid mantle flow in subduction zones as a global process and the non-Newtonian rheology as a mechanism for decoupling the mantle from lithospheric plate motion.

  18. Integrated Geophysical Survey on Deák Ferenc Sluice in Hungary

    NASA Astrophysics Data System (ADS)

    Kanli, A. I.

    2015-12-01

    ALI ISMET KANLI1*, G. TALLER2, Z. PRONAY2, P. TILDY2, P. NAGY3, E. TOROS2 *1Istanbul University, Turkey, kanli@istanbul.edu.tr, 2Geological and Geophysical Institute of Hungary,3MinGeo, Hungary The Ferenc Channel is one of the main irrigation and ship channel in south of Hungary, existing from 1801. The water level is controlled by the Deák Ferenc Sluice in the channel which was constructed in 1875. At that time, the sluice was unique in Europe with its two channels and brick-walls. The west channel was used for controlling the amount of water and the east channel was used for shipping. In the study, before starting to the restoration and reinforcement plannings at the sluice, non-destructive geophysical investigations were executed. In the first stage, ultra-high frequency seismic (80 kHz) and acoustic (5 kHz) investigations of the floor slab were carried out from a boat on the water level. Due to the water level was approximately 2 m, we could use the advantage of the water ensuring very good coupling with seismic sensors for high frequency seismic and acoustic measurements. In the second stage, resistivity measurements were carried out in the eastern part of the sluice which was used as the shipping channel. Three profiles were measured to map the resistivity distribution of the slab. In the third stage, for better understanding the stability conditions of the walls and easy to compare with the data of GPR measurements, the wall of the sluice were investigated by a simple seismic direct wave method using seismic P-waves for mapping seismic velocities. The last stage of the survey was the GPR measurements that were carried out both on the walls and on the slab of the sluice. During the investigation, the channels were empty and without water. The integrated survey and the interpretation of the results showed us that there were some faults, cracks and voids in the slab existed in the whole grossness of the slab and the brick walls were builded from inhomogenous construction material. Integrated geophysical surveys provided optimum solutions for planning restoration and reinforcement work on this ancient and very old building structure. Acknowledgment: Ali Ismet Kanli was supported by The Division of Scientific Research Projects of Istanbul University, International Research Projects, Project number: IRP-50242.

  19. Separate zones of sulfate and sulfide release from subducted mafic oceanic crust

    NASA Astrophysics Data System (ADS)

    Tomkins, Andrew G.; Evans, Katy A.

    2015-10-01

    Liberation of fluids during subduction of oceanic crust is thought to transfer sulfur into the overlying sub-arc mantle. However, despite the importance of sulfur cycling through magmatic arcs to climate change, magma oxidation and ore formation, there has been little investigation of the metamorphic reactions responsible for sulfur release from subducting slabs. Here, we investigate the relative stability of anhydrite (CaSO4) and pyrite (FeS2) in subducted basaltic oceanic crust, the largest contributor to the subducted sulfur budget, to place constraints on the processes controlling sulfur release. Our analysis of anhydrite stability at high pressures suggests that this mineral should dominantly dissolve into metamorphic fluids released across the transition from blueschist to eclogite facies (∼450-650 °C), disappearing at lower temperatures on colder geothermal trajectories. In contrast, we suggest that sulfur release via conversion of pyrite to pyrrhotite occurs at temperatures above 750 °C. This higher temperature stability is indicated by the preservation of pyrite-bornite inclusions in coesite-bearing eclogites from the Sulu Belt in China, which reached temperatures of at least 750 °C. Thus, sulfur may be released from subducting slabs in two separate pulses; (1) varying proportions of SO2, HSO4- and H2S are released via anhydrite breakdown at the blueschist-eclogite transition, promoting oxidation of remaining silicates in some domains, and (2) H2S is released via pyrite breakdown well into the eclogite facies, which may in some circumstances coincide with slab melting or supercritical liquid generation driven by influx of serpentinite-derived fluids. These results imply that the metallogenic potential in the sub-arc mantle above the subducting slab varies as a function of subduction depth, having the greatest potential above the blueschist-eclogite transition given the association between oxidised magmas and porphyry Cu(-Au-Mo) deposits. We speculate that this zoned sulfur liberation might be one of the factors that lead to the apparently redox-influenced zoned distribution of ore deposit types in the Andean arc. Furthermore, given the lack of sulfate-associated sea floor oxidation prior to the second great oxidation event, the pattern of sulfur transfer from the slab to the sub-arc mantle likely changed over time, becoming shallower and more oxidised from the Neoproterozoic onwards.

  20. Advanced Neutron Radiographic Equipment within the US Army

    DTIC Science & Technology

    2014-01-29

    generator was then placed into a moderator assembly made mainly of high density polyethylene ( HDPE ), with a collimator that was a gadolinium (Gd) coated...port made with various slabs, bricks, sheets, and foils of materials containing lead, boron, and HDPE . This port merely functioned as a scatter...conical inserts made of HDPE , lead, and Gd infused paint. The trial experiments have shown that with the system running at its designed maximum power

  1. Design concepts for pressurized lunar shelters utilizing indigenous materials

    NASA Technical Reports Server (NTRS)

    Happel, John Amin; Willam, Kaspar; Shing, Benson

    1991-01-01

    The objective is to design a pressurized shelter build of indigenous lunar material. The topics are presented in viewgraph form and include the following: lunar conditions which impact design; secondary factors; review of previously proposed concepts; cross section of assembly facility; rationale for indigenous materials; indigenous material choices; cast basalt properties; design variables; design 1, cylindrical segments; construction sequence; design 2, arch-slabs with post-tensioned ring girders; and future research.

  2. 53. Photocopied August 1978. DERRICKS AND GENERAL VIEW OF PIT ...

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

    53. Photocopied August 1978. DERRICKS AND GENERAL VIEW OF PIT WALLS, POWER HOUSE, NOVEMBER 7, 1900. THE MONOLITHIC BASES OF THESE WALLS PRIOR TO THE ERECTION OF THE PRE-MOULDED BLOCKS APPEAR TO THE RIGHT. ASSEMBLED WALLS ARE ON THE LEFT. NOTE THAT THE MONOLITHIC FLOORS FOR THE TAIL PITS HAVE BEEN POURED IN THE FIVE RACES ON THE RIGHT, BUT NOT IN THE THREE CLOSEST TO THE ALREADY-ASSEMBLED WALLS. (103) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  3. VIEW FROM THE PRODUCTION FLOOR OF BUILDING 460, LOOKING WEST. ...

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

    VIEW FROM THE PRODUCTION FLOOR OF BUILDING 460, LOOKING WEST. THE BUILDING 460 HOUSED EQUIPMENT, SYSTEMS, AND PERSONNEL FOR FABRICATION, ASSEMBLY, AND TESTING OF STAINLESS STEEL COMPONENTS SUCH AS RESERVOIRS, TUBES, AND NON-FISSILE TRIGGER COMPONENTS. THE PHOTOGRAPH SHOWS A T-BASED LATHE WITH AN OPTICAL COMPARITOR FOR MACHINING OF STAINLESS STEEL IN THE LOWER LEFT CORNER. THE DRUM IN THE LOWER RIGHT CORNER CONTAINS STAINLESS STEEL TURNING COLLECTED FROM THE LATHE. (9/11/85) - Rocky Flats Plant, Stainless Steel & Non-Nuclear Components Manufacturing, Southeast corner of intersection of Cottonwood & Third Avenues, Golden, Jefferson County, CO

  4. 39. INTERIOR VIEW TO THE NORTH OF A WORK STATION ...

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

    39. INTERIOR VIEW TO THE NORTH OF A WORK STATION WITH MANIPULATOR ARMS IN THE SOUTH CORRIDOR OF THE SECOND FLOOR. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  5. THE CALCULATION OF BURNABLE POISON CORRECTION FACTORS FOR PWR FRESH FUEL ACTIVE COLLAR MEASUREMENTS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Croft, Stephen; Favalli, Andrea; Swinhoe, Martyn T.

    2012-06-19

    Verification of commercial low enriched uranium light water reactor fuel takes place at the fuel fabrication facility as part of the overall international nuclear safeguards solution to the civilian use of nuclear technology. The fissile mass per unit length is determined nondestructively by active neutron coincidence counting using a neutron collar. A collar comprises four slabs of high density polyethylene that surround the assembly. Three of the slabs contain {sup 3}He filled proportional counters to detect time correlated fission neutrons induced by an AmLi source placed in the fourth slab. Historically, the response of a particular collar design to amore » particular fuel assembly type has been established by careful cross-calibration to experimental absolute calibrations. Traceability exists to sources and materials held at Los Alamos National Laboratory for over 35 years. This simple yet powerful approach has ensured consistency of application. Since the 1980's there has been a steady improvement in fuel performance. The trend has been to higher burn up. This requires the use of both higher initial enrichment and greater concentrations of burnable poisons. The original analytical relationships to correct for varying fuel composition are consequently being challenged because the experimental basis for them made use of fuels of lower enrichment and lower poison content than is in use today and is envisioned for use in the near term. Thus a reassessment of the correction factors is needed. Experimental reassessment is expensive and time consuming given the great variation between fuel assemblies in circulation. Fortunately current modeling methods enable relative response functions to be calculated with high accuracy. Hence modeling provides a more convenient and cost effective means to derive correction factors which are fit for purpose with confidence. In this work we use the Monte Carlo code MCNPX with neutron coincidence tallies to calculate the influence of Gd{sub 2}O{sub 3} burnable poison on the measurement of fresh pressurized water reactor fuel. To empirically determine the response function over the range of historical and future use we have considered enrichments up to 5 wt% {sup 235}U/{sup tot}U and Gd weight fractions of up to 10 % Gd/UO{sub 2}. Parameterized correction factors are presented.« less

  6. Machined Titanium Heat-Pipe Wick Structure

    NASA Technical Reports Server (NTRS)

    Rosenfeld, John H.; Minnerly, Kenneth G.; Gernert, Nelson J.

    2009-01-01

    Wick structures fabricated by machining of titanium porous material are essential components of lightweight titanium/ water heat pipes of a type now being developed for operation at temperatures up to 530 K in high-radiation environments. In the fabrication of some prior heat pipes, wicks have been made by extruding axial grooves into aluminum unfortunately, titanium cannot be extruded. In the fabrication of some other prior heat pipes, wicks have been made by in-situ sintering of metal powders shaped by the use of forming mandrels that are subsequently removed, but in the specific application that gave rise to the present fabrication method, the required dimensions and shapes of the heat-pipe structures would make it very difficult if not impossible to remove the mandrels due to the length and the small diameter. In the present method, a wick is made from one or more sections that are fabricated separately and assembled outside the tube that constitutes the outer heat pipe wall. The starting wick material is a slab of porous titanium material. This material is machined in its original flat configuration to form axial grooves. In addition, interlocking features are machined at the mating ends of short wick sections that are to be assembled to make a full-length continuous wick structure. Once the sections have been thus assembled, the resulting full-length flat wick structure is rolled into a cylindrical shape and inserted in the heatpipe tube (see figure). This wick-structure fabrication method is not limited to titanium/water heat pipes: It could be extended to other heat pipe materials and working fluids in which the wicks could be made from materials that could be pre-formed into porous slabs.

  7. Occurrence and attempted mitigation of carbon dioxide in a home constructed on reclaimed coal-mine spoil, Pike County, Indiana

    USGS Publications Warehouse

    Robinson, Bret A.

    2010-01-01

    In recent years carbon dioxide intrusion has become recognized as a potentially serious health threat where homes are constructed on or near reclaimed surface coal mines. When carbon dioxide invades the living space of a home, it can collect near the floor, displace the oxygen there, and produce an oxygen-deficient environment. In this investigation, several lines of inquiry were pursued to determine the environmental factors that most influence carbon dioxide intrusion at a Pike County, Ind., home where this phenomenon is known to occur. It was found that carbon dioxide intrusion events at the home are most closely tied to rapid drops in barometric pressure and rainfall. Other researchers have shown that windy conditions and periods of cold weather also can contribute to soil-gas intrusion to structures. From this, a conceptual model was developed to illustrate the influence of these four meteorological conditions. Additionally, three mitigation methods-block-wall depressurization, block-wall and sub-slab depressurization, and block-wall and sub-slab pressurization-were applied successively to the study-site home, and environmental data were collected to evaluate the effectiveness of each mitigation method. In each case, it was found that these methods did not ensure a safe environment when meteorological conditions were favorable for carbon dioxide intrusion.

  8. Phantom Preparation and Optical Property Determination

    NASA Astrophysics Data System (ADS)

    He, Di; He, Jie; Mao, Heng

    2018-12-01

    Tissue-like optical phantoms are important in testing new imaging algorithms. Homogeneous optical phantoms with determined optical properties are the first step of making a proper heterogeneous phantom for multi-modality imaging. Typical recipes for such phantoms consist of epoxy resin, hardener, India ink and titanium oxide. By altering the concentration of India ink and titanium oxide, we are able to get multiple homogeneous phantoms with different absorption and scattering coefficients by carefully mixing all the ingredients. After fabricating the phantoms, we need to find their individual optical properties including the absorption and scattering coefficients. This is achieved by solving diffusion equation of each phantom as a homogeneous slab under canonical illumination. We solve the diffusion equation of homogeneous slab in frequency domain and get the formula for theoretical measurements. Under our steady-state diffused optical tomography (DOT) imaging system, we are able to obtain the real distribution of the incident light produced by a laser. With this source distribution we got and the formula we derived, numerical experiments show how measurements change while varying the value of absorption and scattering coefficients. Then we notice that the measurements alone will not be enough for us to get unique optical properties for steady-state DOT problem. Thus in order to determine the optical properties of a homogeneous slab we want to fix one of the coefficients first and use optimization methods to find another one. Then by assemble multiple homogeneous slab phantoms with different optical properties, we are able to obtain a heterogeneous phantom suitable for testing multi-modality imaging algorithms. In this paper, we describe how to make phantoms, derive a formula to solve the diffusion equation, demonstrate the non-uniqueness of steady-state DOT problem by analysing some numerical results of our formula, and finally propose a possible way to determine optical properties for homogeneous slab for our future work.

  9. DETAIL VIEW OF WINCH USED TO RAISE AND LOWER HINGED ...

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

    DETAIL VIEW OF WINCH USED TO RAISE AND LOWER HINGED SECTION OF THIRD FLOOR LEVEL, PLATFORM D-SOUTH, HB-3, FACING WEST - Cape Canaveral Air Force Station, Launch Complex 39, Vehicle Assembly Building, VAB Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  10. Workers in the VAB move sling into place to lift Columbia to mobile launcher

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Workers in the Vehicle Assembly Building (VAB) move a specially-built sling into place to lift Orbiter Columbia from the transfer aisle to the mobile launcher platform (27015); Columbia is lifted from the floor of the VAB transfer aisle (27016).

  11. Submillimeter bolt location in car bodywork for production line quality inspection

    NASA Astrophysics Data System (ADS)

    Altamirano-Robles, Leopoldo; Arias-Estrada, Miguel; Alviso-Quibrera, Samuel; Lopez-Lopez, Aurelio

    2000-03-01

    In the automotive industry, a vehicle begins with the construction of the vehicle floor. Later on, several robots weld a series of bolts to this floor which are used to fix other parts. Due to several problems, like welding tools wearing, robot miscalibration or momentary low power supply, among others, some bolts are incorrectly positioned or are not present at all, bringing problems and delays in the next work cells. Therefore, it is of importance to verify the quality of welded parts before the following assembly steps. A computer vision system is proposed in order to locate autonomously the presence and quality of the bolts. The system should carry on the inspection in real time at the car assembly line under the following conditions: without touching the bodywork, with a precision in the submillimeter range and in few seconds. In this paper we present a basic computer vision system for bolt location in the submillimeter range. We analyze three arrangements of the system components (camera and illumination sources) that produce different results in the localization. Results are presented and compared for the three approaches obtained under laboratory conditions. The algorithms were tested in the assembling line. Variations up to one millimeter in the welded position of the bolts were observed.

  12. KSC-2009-1772

    NASA Image and Video Library

    2009-02-21

    CAPE CANAVERAL, Fla. – In the Assembly and Refurbishment Facility, or ARF, at NASA's Kennedy Space Center, an overhead crane lowers the frustum for the Ares I-X test rocket onto supports on the floor. The frustum is the last manufactured section of the Ares I-X. Resembling a giant funnel, the frustum's function is to transition the primary flight loads from the rocket's upper stage to the first stage. The frustum is located between the forward skirt extension and the upper stage of the Ares I-X. The frustum will be integrated with the forward skirt and forward skirt extension, which already are in the ARF. That will complete the forward assembly. The assembly then will be moved to the Vehicle Assembly Building for stacking operations, which are scheduled to begin in April. Photo credit: NASA/Kim Shiflett

  13. KSC-2009-1771

    NASA Image and Video Library

    2009-02-21

    CAPE CANAVERAL, Fla. – In the Assembly and Refurbishment Facility, or ARF, at NASA's Kennedy Space Center, an overhead crane lowers the frustum for the Ares I-X test rocket onto supports on the floor. The frustum is the last manufactured section of the Ares I-X. Resembling a giant funnel, the frustum's function is to transition the primary flight loads from the rocket's upper stage to the first stage. The frustum is located between the forward skirt extension and the upper stage of the Ares I-X. The frustum will be integrated with the forward skirt and forward skirt extension, which already are in the ARF. That will complete the forward assembly. The assembly then will be moved to the Vehicle Assembly Building for stacking operations, which are scheduled to begin in April. Photo credit: NASA/Kim Shiflett

  14. Arc/Forearc Lengthening at Plate Triple Junctions and the Formation of Ophiolitic Soles

    NASA Astrophysics Data System (ADS)

    Casey, John; Dewey, John

    2013-04-01

    The principal enigma of large obducted ophiolite slabs is that they clearly must have been generated by some form of organized sea-floor spreading/plate-accretion, such as may be envisioned for the oceanic ridges, yet the volcanics commonly have arc affinity (Miyashiro) with boninites (high-temperature/low-pressure, high Mg and Si andesites), which are suggestive of a forearc origin. PT conditions under which boninites and metamorphic soles form and observations of modern forearc systems lead us to the conclusion that ophiolite formation is associated with overidding plate spreading centers that intersect the trench to form ridge-trench-trench of ridge-trench-tranform triple junctions. The spreading centers extend and lengthen the forearc parallel to the trench and by definition are in supra-subduction zone (SSZ) settings. Many ophiolites likewise have complexly-deformed associated mafic-ultramafic assemblages that suggest fracture zone/transform t along their frontal edges, which in turn has led to models involving the nucleation of subduction zones on fracture zones or transpressional transforms. Hitherto, arc-related sea-floor-spreading has been considered to be either pre-arc (fore-arc boninites) or post-arc (classic Karig-style back arc basins that trench-parallell split arcs). Syn-arc boninites and forearc oceanic spreading centers that involve a stable ridge/trench/trench triple or a ridge-trench-transform triple junction, the ridge being between the two upper plates, are consistent with large slab ophiolite formation in a readied obduction settting. The direction of subduction must be oblique with a different sense in the two subduction zones and the oblique subduction cannot be partitioned into trench orthogonal and parallel strike-slip components. As the ridge spreads, new oceanic lithosphere is created within the forearc, the arc and fore-arc lengthen significantly, and a syn-arc ophiolite forearc complex is generated by this mechanism. The ophiolite ages along arc-strike; a distinctive diachronous MORB-like to boninitic to arc volcanic stratigraphy develops vertically in the forearc and eruption centers progressively migrate from the forearc back to the main arc massif with time. Dikes in the ophiolite are highly oblique to the trench (as are back-arc magnetic anomalies. Boninites and high-mg andesites are generated in the fore-arc under the aqueous, low pressure/high temperature, regime at the ridge above the instantaneously developed subducting and dehydrating slab. Subducted slab refrigeration of the hanging wall ensues and accretion of MORB metabasites to the hanging wall of the subduction channel initiates. Mafic protolith garnet/two pyroxene granulites to greenschists accrete and form the inverted P and T metamorphic sole prior to obduction. Sole accretion of lithosphere begins at about 1000°C and the full retrogressive sole may be fully formed within ten to fifteen million years of accretion, at which time low grade subduction melanges accrete. Obduction of the SSZ forearc ophiolite with its subjacent metamorphic sole occurs whenever the oceanic arc attempts subduction of a stable buoyant continental or back arc margin.

  15. 77 FR 52680 - Foreign-Trade Zone 242-Boundary County, ID, Notification of Proposed Production Activity, AREVA...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-30

    ... County, ID, Notification of Proposed Production Activity, AREVA Enrichment Services, LLC, (Gas Centrifuge... being requested for the storage, manipulation, assembly and installation of gas centrifuge production... pipework, centrifuge floor-mounting elements, UF6 pipework/fittings, parts of cascades, vacuum pumps, UF6...

  16. KSC-2009-1314

    NASA Image and Video Library

    2009-01-22

    CAPE CANAVERAL, Fla. – Inside the Assembly and Refurbishment Facility at NASA's Kennedy Space Center in Florida, the Ares I-X forward skirt is lowered onto supports on the floor. United Space Alliance, under a subcontract to ATK, will complete the integration and assembly of the forward skirt components in the ARF. It will then be moved to the Vehicle Assembly Building high bay 3 for stacking operations. The forward skirt is the initial piece of first-stage hardware in preparation for the July 2009 test flight of the agency's next-generation spacecraft and launch vehicle system. Built entirely of armored steel, the 14,000-pound segment is seven feet tall and 12-1/4 feet wide. Photo credit: NASA/Kim Shiflett

  17. Magnetoplasmonic nanostructures based on nickel inverse opal slabs

    NASA Astrophysics Data System (ADS)

    Grunin, A. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Fedyanin, A. A.

    2012-04-01

    Nanostructured nickel surfaces representing periodically arranged spherical voids in a nickel film are obtained by electrochemical deposition through a self-assembled opaline template. Excitation of surface plasmon-polaritons (SPPs) on the surface of the sample is experimentally observed as the Wood's anomaly in the reflectance spectra. Transversal magneto-optical Kerr effect (TMOKE) spectra are measured at the different angles of incidence and azimuthal angles. The two- to-threefold enhancement of TMOKE caused by the excitation of mixed plasmons in two selected azimuthal configurations is observed.

  18. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richer, Jeff; Frimeth, Jeff; Nesbitt, James

    Purpose: In Ontario, shielding for all X-ray machines, including CT scanners, must be evaluated according to Safety Code 20A (Health Canada, 1983) which is based on NCRP-49 (NCRP, 1976). NCRP-147 (NCRP, 2004) is the international standard for shielding calculations of CT scanners and is also referenced in Safety Code 35 (Health Canada, 2008) which, was published to supersede SC20A. The goal of this work is to demonstrate the cost effectiveness of NCRP-147 for CT scanner shielding. Methods: CT scanner shielding calculations are performed using SC20A and NCRP-147: A room located on the third floor with the nearest building 75m awaymore » A room with high occupancy uncontrolled adjacent spaces Two side by side rooms on the main floor Results: 1. SC20A: The exterior windows required 0.1mm of Pb to protect the public who may occupy the building at 75m. 1. NCRP-147: No additional shielding required. 2. SC20A: Two walls adjacent to high occupancy uncontrolled space required an additional 1.58mm Pb. 2. NCRP-147: No additional shielding required. 3. SC20A: The entire floor and ceiling slabs in both rooms required an additional 0.79mm Pb. In addition, 0.79mm Pb was added to the walls from the ceiling to overlap the existing Pb shielding in the walls. 3. NCRP-147: No additional shielding required. Conclusion: The application of NCRP Report No. 147 affords the required protection to staff and the public, in the true spirit of the ALARA principle, taking into account relevant social and economic factors.« less

  19. General view of the Space Shuttle Main Engine (SSME) assembly ...

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

    General view of the Space Shuttle Main Engine (SSME) assembly with the expansion nozzle removed and resting on a cushioned mat on the floor of the SSME Processing Facility. The most prominent features in this view are the Low-pressure Fuel Turbopump discharge Duct looping from the upper left side of the engine assembly to the lower left side of the assembly, the Low-Pressure Oxidizer Turbopump (LPOTP) is on the upper left of the assembly in this view and the LPOTP Discharge Duct loops from the upper left to upper right. The sphere in the middle right side of the assembly in this view is the POGO System Accumulator , the partial sphere to its left and slightly more toward the center of the assembly is the Heat Exchanger on the Oxidizer Preburner side of the Hot Gas Manifold, beneath that is the High-Pressure Oxidizer Turbopump (HPOTP) and the HPOTP Discharge duct loops from the pump around to the lower left of the assembly. The Pneumatic Control Assembly is in the approximate center of the engine assembly in this view. - Space Transportation System, Space Shuttle Main Engine, Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  20. Air slab-correction for Γ-ray attenuation measurements

    NASA Astrophysics Data System (ADS)

    Mann, Kulwinder Singh

    2017-12-01

    Gamma (γ)-ray shielding behaviour (GSB) of a material can be ascertained from its linear attenuation coefficient (μ, cm-1). Narrow-beam transmission geometry is required for μ-measurement. In such measurements, a thin slab of the material has to insert between point-isotropic γ-ray source and detector assembly. The accuracy in measurements requires that sample's optical thickness (OT) remain below 0.5 mean free path (mfp). Sometimes it is very difficult to produce thin slab of sample (absorber), on the other hand for thick absorber, i.e. OT >0.5 mfp, the influence of the air displaced by it cannot be ignored during μ-measurements. Thus, for a thick sample, correction factor has been suggested which compensates the air present in the transmission geometry. The correction factor has been named as an air slab-correction (ASC). Six samples of low-Z engineering materials (cement-black, clay, red-mud, lime-stone, cement-white and plaster-of-paris) have been selected for investigating the effect of ASC on μ-measurements at three γ-ray energies (661.66, 1173.24, 1332.50 keV). The measurements have been made using point-isotropic γ-ray sources (Cs-137 and Co-60), NaI(Tl) detector and multi-channel-analyser coupled with a personal computer. Theoretical values of μ have been computed using a GRIC2-toolkit (standardized computer programme). Elemental compositions of the samples were measured with Wavelength Dispersive X-ray Fluorescence (WDXRF) analyser. Inter-comparison of measured and computed μ-values, suggested that the application of ASC helps in precise μ-measurement for thick samples of low-Z materials. Thus, this hitherto widely ignored ASC factor is recommended to use in similar γ-ray measurements.

  1. Results of borehole geophysical logging and aquifer-isolation tests conducted in the John Wagner and Sons, Inc. former production well, Ivyland, Pennsylvania

    USGS Publications Warehouse

    Sloto, Ronald A.

    1997-01-01

    A suite of borehole geophysical logs and heat-pulse-flowmeter measurements run in the former production well at the John Wagner and Sons, Inc. plant indicate two zones of borehole flow. In the upper part of the well, water enters the borehole through a fracture at 90 ft (feet) below floor level, moves upward, and exits the borehole through a fracture at 72 ft below floor level. Water also enters the borehole through fractures at 205-213, 235, and 357 ft below floor level; moves downward; and exits the borehole through fractures at 450-459, 468-470, and 483-490 ft below floor level. Five zones were selected for aquifer-isolation (packer) tests on the basis of borehole geophysical logs. The zones were isolated using a straddle-packer assembly. The lowermost three zones (below 248, 223 to 248, and 198 to 223 ft below floor level) were hydraulically isolated from zones above and below. Specific capacities were 0.12, 0.034, and 0.15 gallons per minute per foot, respectively. The hydrograph from zone 2 (223 to 248 ft below floor level) showed interference from a nearby pumping well. For the upper two zones (81 to 106 and 57 to 81 ft below floor level), similar drawdowns in the isolated zone and the zones above and below the isolated zone indicate that these fractures are hydraulically connected outside the borehole in the unconfined part of the Stockton Formation. The specific capacity of zones 4 and 5 are similar—0.82 and 0.61, respectively.

  2. Modeling Earthquake Rupture and Corresponding Tsunamis Along a Segment of the Alaskan-Aleutian Megathrust

    NASA Astrophysics Data System (ADS)

    Ryan, K. J.; Geist, E. L.; Oglesby, D. D.; Kyriakopoulos, C.

    2016-12-01

    Motivated by the 2011 Mw 9 Tohoku-Oki event, we explore the effects of realistic fault dynamics on slip, free surface deformation, and the resulting tsunami generation and local propagation from a hypothetical Mw 9 megathrust earthquake along the Alaskan-Aleutian (A-A) Megathrust. We demonstrate three scenarios: a spatially-homogenous prestress and frictional parameter model and two models with rate-strengthening-like friction (e.g., Dieterich, 1992). We use a dynamic finite element code to model 3-D ruptures, using time-weakening friction (Andrews, 2004) as a proxy for rate-strengthening friction, along a portion of the A-A subduction zone. Given geometric, material, and plate-coupling data along the A-A megathrust assembled from the Science Application for Risk Reduction (SAFRR) team (e.g., Bruns et al., 1987; Hayes et al., 2012; Johnson et al., 2004; Santini et al., 2003; Wells at al., 2003), we are able to dynamically model rupture. Adding frictional-strengthening to a region of the fault reduces both average slip and free surface displacement above the strengthening zone, with the magnitude of the reductions depending on the strengthening zone location. Corresponding tsunami models, which use a finite difference method to solve the long-wave equations (e.g., Liu et al., 1995; Satake, 2002; Shuto, 1991), match sea floor displacement, in time, to the free surface displacement from the rupture models. Tsunami models show changes in local peak amplitudes and beaming patterns for each slip distribution. Given these results, other heterogeneous parameterizations, with respect to prestress and friction, still need to be examined. Additionally, a more realistic fault geometry will likely affect the rupture dynamics. Thus, future work will incorporate stochastic stress and friction distributions as well as a more complex fault geometry based on Slab 1.0 (Hayes et al., 2012).

  3. Frequency selection for coda wave interferometry in concrete structures.

    PubMed

    Fröjd, Patrik; Ulriksen, Peter

    2017-09-01

    This study contributes to the establishment of frequency recommendations for use in coda wave interferometry structural health monitoring (SHM) systems for concrete structures. To this end, codas with widely different central frequencies were used to detect boreholes with different diameters in a large concrete floor slab, and to track increasing damage in a small concrete beam subjected to bending loads. SHM results were obtained for damage that can be simulated by drilled holes on the scale of a few mm or microcracks due to bending. These results suggest that signals in the range of 50-150kHz are suitable in large concrete structures where it is necessary to account for the high attenuation of high-frequency signals. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Support of Gulf of Mexico Hydrate Research Consortium: Activities to Support Establishment of a Sea Floor Monitoring Station Project

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    J. Robert Woolsey; Thomas M. McGee; Carol Blanton Lutken

    2007-03-31

    The Gulf of Mexico Hydrates Research Consortium (GOM-HRC) was established in 1999 to assemble leaders in gas hydrates research. The Consortium is administered by the Center for Marine Resources and Environmental Technology, CMRET, at the University of Mississippi. The primary objective of the group is to design and emplace a remote monitoring station or sea floor observatory (MS/SFO) on the sea floor in the northern Gulf of Mexico by the year 2007, in an area where gas hydrates are known to be present at, or just below, the sea floor. This mission, although unavoidably delayed by hurricanes and other disturbances,more » necessitates assembling a station that will monitor physical and chemical parameters of the marine environment, including sea water and sea-floor sediments, on a more-or-less continuous basis over an extended period of time. In 2005, biological monitoring, as a means of assessing environmental health, was added to the mission of the MS/SFO. Establishment of the Consortium has succeeded in fulfilling the critical need to coordinate activities, avoid redundancies and communicate effectively among researchers in the arena of gas hydrates research. Complementary expertise, both scientific and technical, has been assembled to promote innovative research methods and construct necessary instrumentation. The observatory has now achieved a microbial dimension in addition to the geophysical, geological, and geochemical components it had already included. Initial components of the observatory, a probe that collects pore-fluid samples and another that records sea floor temperatures, were deployed in Mississippi Canyon 118 (MC118) in May of 2005. Follow-up deployments, planned for fall 2005, had to be postponed due to the catastrophic effects of Hurricane Katrina (and later, Rita) on the Gulf Coast. Station/observatory completion, anticipated for 2007, will likely be delayed by at least one year. These delays caused scheduling and deployments difficulties but many sensors and instruments were completed during this period. Software has been written that will accommodate the data that the station retrieves, when it begins to be delivered. In addition, new seismic data processing software has been written to treat the peculiar data to be received by the vertical line array (VLA) and additional software has been developed that will address the horizontal line array (HLA) data. These packages have been tested on data from the test deployments of the VLA and on data from other, similar, areas of the Gulf (in the case of the HLA software). The CMRET has conducted one very significant research cruise during this reporting period: a March cruise to perform sea trials of the Station Service Device (SSD), the custom Remotely Operated Vehicle (ROV) built to perform several of the unique functions required for the observatory to become fully operational. March's efforts included test deployments of the SSD and Florida Southern University's mass spectrometer designed to measure hydrocarbon gases in the water column and The University of Georgia's microbial collector. The University of Georgia's rotational sea-floor camera was retrieved as was Specialty Devices storm monitor array. The former was deployed in September and the latter in June, 2006. Both were retrieved by acoustic release from a dispensable weight. Cruise participants also went prepared to recover any and all instruments left on the sea-floor during the September Johnson SeaLink submersible cruise. One of the pore-fluid samplers, a small ''peeper'' was retrieved successfully and in fine condition. Other instrumentation was left on the sea-floor until modifications of the SSD are complete and a return cruise is accomplished.« less

  5. KSC-2009-1768

    NASA Image and Video Library

    2009-02-21

    CAPE CANAVERAL, Fla. – In the Assembly and Refurbishment Facility, or ARF, at NASA's Kennedy Space Center, workers help guide the frustum as a cable lifts it from the transporter. The last manufactured section of the Ares I-X test rocket, the frustum will be moved from the transporter to supports on the floor. Resembling a giant funnel, the frustum's function is to transition the primary flight loads from the rocket's upper stage to the first stage. The frustum is located between the forward skirt extension and the upper stage of the Ares I-X. The frustum will be integrated with the forward skirt and forward skirt extension, which already are in the ARF. That will complete the forward assembly. The assembly then will be moved to the Vehicle Assembly Building for stacking operations, which are scheduled to begin in April. Photo credit: NASA/Kim Shiflett

  6. General view of the Space Shuttle Main Engine (SSME) assembly ...

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

    General view of the Space Shuttle Main Engine (SSME) assembly with the expansion nozzle removed and resting on a cushioned mat on the floor of the SSME Processing Facility. The most prominent features in this view are the Low-pressure oxidizer Turbopump discharge Duct looping from the upper left side of the engine assembly to the lower left side of the assembly, the Low-Pressure Fuel Turbopump (LPFTP) is on the upper left of the assembly in this view and the LPFTP Discharge Duct loops from the upper left to upper right then turns back and down the assembly to the High-Pressure Fuel Turbopump on the lower right of the assembly. The Engine Controller and the Main fuel Valve Hydraulic Actuator are on the lower left portion of the assembly. The vertical rod that is in the approximate center of the engine assembly is a piece of ground support equipment call a Gimbal Actuator Replacement Strut which are used on the SSMEs when they are not installed in an orbiter. - Space Transportation System, Space Shuttle Main Engine, Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  7. Chapter 6:Engineered trusses from undervalued hardwoods

    Treesearch

    Robert J. Ross; Brian K. Brashaw

    2005-01-01

    A significant volume of softwood lumber is used in engineered truss assemblies. Metal plate connected (MPC) trusses are commonly used in residential construction for both roof and floor applications. Currently, there are no truss manufacturers producing MPC trusses with hardwood lumber, primarily as a consequence of a lack of technical data on the performance of...

  8. 33. INTERIOR VIEW TO THE SOUTHWEST OF ROOM 135, A ...

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

    33. INTERIOR VIEW TO THE SOUTHWEST OF ROOM 135, A FIRST FLOOR CORRIDOR AND VIEWING GALLERY NEXT TO THE POST-MORTEM CELLS. VIEWING AND WORK STATIONS ARE ON THE WEST WALL. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  9. 77 FR 3382 - Airworthiness Directives; Agusta S.p.A. Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-24

    ... Transportation (DOT). ACTION: Final rule; request for comments. SUMMARY: We are adopting a new airworthiness... fatigue crack found in the left elevator assembly along the riveting of the upper skin to the fourth rib... Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE...

  10. The Relationships of Upper Plate Ridge-Trench-Trench and Ridge-Trench-Transform Triple Junction Evolution to Arc Lengthening, Subduction Zone initiation and Ophiolitic Forearc Obduction

    NASA Astrophysics Data System (ADS)

    Casey, J.; Dewey, J. F.

    2013-12-01

    The principal enigma of large obducted ophiolite slabs is that they clearly must have been generated by some form of organized sea-floor spreading/plate-accretion, such as may be envisioned for the oceanic ridges, yet the volcanics commonly have arc affinity (Miyashiro) with boninites (high-temperature/low-pressure, high Mg and Si andesites), which are suggestive of a forearc origin. PT conditions under which boninites and metamorphic soles form and observations of modern forearc systems lead us to the conclusion that ophiolite formation is associated with overriding plate spreading centers that intersect the trench to form ridge-trench-trench of ridge-trench-tranform triple junctions. The spreading centers extend and lengthen the forearc parallel to the trench and by definition are in supra-subduction zone (SSZ) settings. Many ophiolites likewise have complexly-deformed associated mafic-ultramafic assemblages that suggest fracture zone/transform along their frontal edges, which in turn has led to models involving the nucleation of subduction zones on fracture zones or transpressional transforms. Hitherto, arc-related sea-floor-spreading has been considered to be either pre-arc (fore-arc boninites) or post-arc (classic Karig-style back arc basins that trench-parallel split arcs). Syn-arc boninites and forearc oceanic spreading centers that involve a stable ridge/trench/trench triple or a ridge-trench-transform triple junction, the ridge being between the two upper plates, are consistent with large slab ophiolite formation in an obduction-ready settting. The direction of subduction must be oblique with a different sense in the two subduction zones and the oblique subduction cannot be partitioned into trench orthogonal and parallel strike-slip components. As the ridge spreads, new oceanic lithosphere is created within the forearc, the arc and fore-arc lengthen significantly, and a syn-arc ophiolite forearc complex is generated by this mechanism. The ophiolite ages along arc-strike; a distinctive diachronous MORB-like to boninitic to arc volcanic stratigraphy develops vertically in the forearc and eruption centers progressively migrate from the forearc back to the main arc massif with time. Dikes in the ophiolite are commonly highly oblique to the trench (as are back-arc magnetic anomalies in modern environments). Boninites and high-mg andesites are generated in the fore-arc under the aqueous, low pressure/high temperature, regime at the ridge above the instantaneously developed subducting and dehydrating slab. We review both modern subduction environments and ancient obducted ophiolite analogues that illustrate this tectonic model for subduction initiation and the creation and rapid divergent-convergent plate tectonic transitions to ophiolitic forearcs.

  11. 100% of the World Ocean Floor Mapped by 2030 - Contribution of the South and West Pacific Regional Data Assembly and Coordination Centre to the Seabed 2030 Initiative

    NASA Astrophysics Data System (ADS)

    Lamarche, G.; Neil, H.; Stagpoole, V. M.; Greenland, A.; Mackay, K.; Black, J.; Griffin, E.

    2017-12-01

    The Seabed 2030 SaWPac Centre (South and West Pacific Ocean Regional Data Assembly and Coordination Centre) has been formed to generate new high resolution ocean floor maps of the western and southern Pacific Ocean. The centre is part of the joint Nippon Foundation and the General Bathymetric Chart of the Oceans (GEBCO) initiative to produce a definitive map of the World Ocean floor by 2030, empowering the world to make policy decisions, use the ocean sustainability and undertake scientific research based on detailed bathymetric information of the Earth's seabed. The SaWPac Centre is based at NIWA Wellington (New Zealand) and includes a collaborative partnership with GNS Science and Land Information New Zealand. It is responsible for the region from South America to Australia, north of latitude 50°S to 10° north of the Equator and the western part of the Northern Pacific Ocean to Russia. The region includes the world's deepest trenches and also covers some of the remotest oceans where bathymetric data form existing ship tracks is spaced up to 100 km apart. The challenge for the SaWPac Centre is to collate and combine all the available bathymetric data from the numerous nations that have surveyed in the region. The centre will also promote efforts to collect new data and contribute to map products generated by the Seabed 2030 global mapping project.

  12. Instrumentation by accelerometers and distributed optical fiber sensors of a real ballastless track structure

    NASA Astrophysics Data System (ADS)

    Chapeleau, Xavier; Cottineau, Louis-Marie; Sedran, Thierry; Cailliau, Joël; Gueguen, Ivan; Dumoulin, Jean

    2015-04-01

    While relatively expensive to build, ballastless track structures are presently seen as an attractive alternative to conventional ballast. Firstly, they are built quickly since the slabs can be cast in place in an automated fashion by a slipform paver. Secondly, with its service life of at least 60 years, they requires little maintenance and hence they offers great availability. Other reasons for using ballastless tracks instead of ballasted tracks are the lack of suitable ballast material and the need of less noise and vibration for high-speed, in particularly. In the framework of a FUI project (n° 072906053), a new ballastless track structure based on concrete slabs was designed and its thermal-mechanical behavior in fatigue under selected mechanical and thermal conditions was tested on a real scale mockup in our laboratory [1,2]. By applying to the slabs both together mechanical stresses and thermal gradients, finite elements simulation and experimental results show that the weather conditions influence significantly the concrete slabs curvatures and by the way, the contact conditions with the underlaying layers. So it is absolutely necessary to take into account this effect in the design of the ballastless track structures in order to guarantee a long target life of at least of 50 years. After design and experimental tests in laboratory, a real ballastless track structure of 1km was built in France at the beginning of year 2013. This structure has 2 tracks on which several trains circulate every day since the beginning of year 2014. Before the construction, it was decided to monitor this structure to verify that the mechanical behavior is conform to the simulations. One part of the instrumentation is dedicated to monitor quasi-continuously the evolution of the curvature of a concrete slab. For this, 2 accelerometers were fixed on the slab under the track. One was placed on the edge and the other in the middle of the slab. The acquisition of the signals by a nano computer (called Pegase and developed at Ifsttar for data acquisition [3]) were performed automatically every time that a threshold is exceeded due to the passage of a train. These data are then send to a web server via a 3G Wireless Network. Many data was thus stored daily for several months. Moreover, several thermocouples were embedded at different depths in order to measure thermal gradients into the track slab. From the accelerometers signals, the deflection of the track slab are then obtained and compared to the measurements of thermal gradients. This comparison show clearly the daily evolution of the curvature with the thermal gradient changes as estimated by the simulation. This result was confirmed indirectly by strain profile measurements obtained by the Rayleigh fiber optic sensing technique. Two fiber optics embedded in the upper and lower part of the foundation slab show that contact conditions between the foundation slab and the track slab change with thermal gradient. 1 - X. Chapeleau, T. Sedran, L.-M. Cottineau, J. Cailliau, F. Taillade, I. Gueguen, J.-M. Henault. Study of ballastless track structure monitoring by distributed optical fiber sensors on a real-scale mockup in laboratory. Engineering Structures, 2013, 56, pp. 1751-1757. 2 - X. Chapeleau, L.-M. Cottineau, T. Sedran, J. Cailliau, I. Gueguen. Instrumentation by distributed optical fiber sensors of a new ballastless track structure. EGU General Assembly 2013, held 7-12 April, 2013 in Vienna, Austria, id. EGU2013-8946 3 - V. Le Cam, L. Lemarchand, L-M. Cottineau and F. Bourquin. Design of a generic smart and wireless sensors network - benefits of emerging technologies. Structural Health Monitoring 2008, 1(1), pp. 598-605.

  13. Fukushima Daiichi Muon Imaging

    NASA Astrophysics Data System (ADS)

    Miyadera, Haruo

    2015-10-01

    Japanese government announced cold-shutdown condition of the reactors at Fukushima Daiichi by the end of 2011, and mid- and long-term roadmap towards decommissioning has been drawn. However, little is known for the conditions of the cores because access to the reactors has been limited by the high radiation environment. The debris removal from the Unit 1 - 3 is planned to start as early as 2020, but the dismantlement is not easy without any realistic information of the damage to the cores, and the locations and amounts of the fuel debris. Soon after the disaster of Fukushima Daiichi, several teams in the US and Japan proposed to apply muon transmission or scattering imagings to provide information of the Fukushima Daiichi reactors without accessing inside the reactor building. GEANT4 modeling studies of Fukushima Daiichi Unit 1 and 2 showed clear superiority of the muon scattering method over conventional transmission method. The scattering method was demonstrated with a research reactor, Toshiba Nuclear Critical Assembly (NCA), where a fuel assembly was imaged with 3-cm resolution. The muon scattering imaging of Fukushima Daiichi was approved as a national project and is aiming at installing muon trackers to Unit 2. A proposed plan includes installation of muon trackers on the 2nd floor (operation floor) of turbine building, and in front of the reactor building. Two 7mx7m detectors were assembled at Toshiba and tested.

  14. Preliminary skyshine calculations for the Poloidal Diverter Tokamak Experiment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nigg, D.W.; Wheeler, F.J.

    1981-01-01

    The Poloidal Diverter Experiment (PDX) facility at Princeton University is the first operating tokamak to require substantial radiation shielding. A calculational model has been developed to estimate the radiation dose in the PDX control room and at the site boundary due to the skyshine effect. An efficient one-dimensional method is used to compute the neutron and capture gamma leakage currents at the top surface of the PDX roof shield. This method employs an S /SUB n/ calculation in slab geometry and, for the PDX, is superior to spherical models found in the literature. If certain conditions are met, the slabmore » model provides the exact probability of leakage out the top surface of the roof for fusion source neutrons and for capture gamma rays produced in the PDX floor and roof shield. The model also provides the correct neutron and capture gamma leakage current spectra and angular distributions, averaged over the top roof shield surface. For the PDX, this method is nearly as accurate as multidimensional techniques for computing the roof leakage and is much less costly. The actual neutron skyshine dose is computed using a Monte Carlo model with the neutron source at the roof surface obtained from the slab S /SUB n/ calculation. The capture gamma dose is computed using a simple point-kernel single-scatter method.« less

  15. Robust Segmentation of Planar and Linear Features of Terrestrial Laser Scanner Point Clouds Acquired from Construction Sites.

    PubMed

    Maalek, Reza; Lichti, Derek D; Ruwanpura, Janaka Y

    2018-03-08

    Automated segmentation of planar and linear features of point clouds acquired from construction sites is essential for the automatic extraction of building construction elements such as columns, beams and slabs. However, many planar and linear segmentation methods use scene-dependent similarity thresholds that may not provide generalizable solutions for all environments. In addition, outliers exist in construction site point clouds due to data artefacts caused by moving objects, occlusions and dust. To address these concerns, a novel method for robust classification and segmentation of planar and linear features is proposed. First, coplanar and collinear points are classified through a robust principal components analysis procedure. The classified points are then grouped using a new robust clustering method, the robust complete linkage method. A robust method is also proposed to extract the points of flat-slab floors and/or ceilings independent of the aforementioned stages to improve computational efficiency. The applicability of the proposed method is evaluated in eight datasets acquired from a complex laboratory environment and two construction sites at the University of Calgary. The precision, recall, and accuracy of the segmentation at both construction sites were 96.8%, 97.7% and 95%, respectively. These results demonstrate the suitability of the proposed method for robust segmentation of planar and linear features of contaminated datasets, such as those collected from construction sites.

  16. Robust Segmentation of Planar and Linear Features of Terrestrial Laser Scanner Point Clouds Acquired from Construction Sites

    PubMed Central

    Maalek, Reza; Lichti, Derek D; Ruwanpura, Janaka Y

    2018-01-01

    Automated segmentation of planar and linear features of point clouds acquired from construction sites is essential for the automatic extraction of building construction elements such as columns, beams and slabs. However, many planar and linear segmentation methods use scene-dependent similarity thresholds that may not provide generalizable solutions for all environments. In addition, outliers exist in construction site point clouds due to data artefacts caused by moving objects, occlusions and dust. To address these concerns, a novel method for robust classification and segmentation of planar and linear features is proposed. First, coplanar and collinear points are classified through a robust principal components analysis procedure. The classified points are then grouped using a new robust clustering method, the robust complete linkage method. A robust method is also proposed to extract the points of flat-slab floors and/or ceilings independent of the aforementioned stages to improve computational efficiency. The applicability of the proposed method is evaluated in eight datasets acquired from a complex laboratory environment and two construction sites at the University of Calgary. The precision, recall, and accuracy of the segmentation at both construction sites were 96.8%, 97.7% and 95%, respectively. These results demonstrate the suitability of the proposed method for robust segmentation of planar and linear features of contaminated datasets, such as those collected from construction sites. PMID:29518062

  17. Short-Term Monitoring Results for Advanced New Construction Test House - Roseville, California

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stecher, D.; Brozyna, K.; Imm, C.

    2013-09-01

    A builder (K. Hovnanian® Homes®), design consultant, and trades collaborated to identify a systems integrated measures package for a 2,253-ft² slab-on-grade ranch house to achieve a modeled energy savings of 60% with respect to the Building America House Simulation Protocols, while minimizing construction costs and without requiring changes to the drawing that would impact local code or zoning approval. The key building improvements were applying R-10 insulation to the slab edge, increasing exterior wall cavity insulation from R-13 to R-15, and increasing attic insulation from R-30 to R-38. Also, the air handling unit was relocated from the attic to conditionedmore » space, and ductwork was relocated along the attic floor with an insulated bulkhead built above it. Short-term testing results showed that duct air leakage was low due to short duct runs and the placement of ductwork in conditioned space. However, during commissioning, the lack of access for servicing the ductwork and dampers in the bulkhead area prevented retroactive balancing of individual branches, resulting in significant differences between specified and measured airflow values for some duct runs. Thermal imaging results performed on the house when operating in both heating and cooling modes validated historic stratification issues of ceiling supply registers with high supply air temperatures. Long-term monitoring results will be detailed in a future report.« less

  18. Three-Dimensional Self-Assembled Photonic Crystal Waveguide

    NASA Astrophysics Data System (ADS)

    Baek, Kang-Hyun

    Photonic crystals (PCs), two- or three-dimensionally periodic, artificial, and dielectric structures, have a specific forbidden band for electromagnetic waves, referred to as photonic bandgap (PBG). The PBG is analogous to the electronic bandgap in natural crystal structures with periodic atomic arrangement. A well-defined and embedded planar, line, or point defect within the PCs causes a break in its structural periodicity, and introduces a state in the PBG for light localization. It offers various applications in integrated optics and photonics including optical filters, sharp bending light guides and very low threshold lasers. Using nanofabrication processes, PCs of the 2-D slab-type and 3-D layer-by-layer structures have been investigated widely. Alternatively, simple and low-cost self-assembled PCs with full 3-D PBG, inverse opals, have been suggested. A template with face centered cubic closed packed structure, opal, may initially be built by self-assembly of colloidal spheres, and is selectively removed after infiltrating high refractive index materials into the interstitials of spheres. In this dissertation, the optical waveguides utilizing the 3-D self-assembled PCs are discussed. The waveguides were fabricated by microfabrication technology. For high-quality colloidal silica spheres and PCs, reliable synthesis, self-assembly, and characterization techniques were developed. Its theoretical and experimental demonstrations are provided and correlated. They suggest that the self-assembled PCs with PBG are feasible for the applications in integrated optics and photonics.

  19. KSC-2009-1767

    NASA Image and Video Library

    2009-02-21

    CAPE CANAVERAL, Fla. – In the Assembly and Refurbishment Facility, or ARF, at NASA's Kennedy Space Center, an overhead crane is attached to the frustum for the Ares I-X test rocket. The frustum is the last manufactured section of the Ares I-X. The frustum will be moved from the transporter to supports on the floor. Resembling a giant funnel, the frustum's function is to transition the primary flight loads from the rocket's upper stage to the first stage. The frustum is located between the forward skirt extension and the upper stage of the Ares I-X. The frustum will be integrated with the forward skirt and forward skirt extension, which already are in the ARF. That will complete the forward assembly. The assembly then will be moved to the Vehicle Assembly Building for stacking operations, which are scheduled to begin in April. Photo credit: NASA/Kim Shiflett

  20. KSC-2009-1769

    NASA Image and Video Library

    2009-02-21

    CAPE CANAVERAL, Fla. – In the Assembly and Refurbishment Facility, or ARF, at NASA's Kennedy Space Center, an overhead crane lifts the frustum for the Ares I-X test rocket from its transporter. The frustum is the last manufactured section of the Ares I-X. The frustum will be moved from the transporter to supports on the floor. Resembling a giant funnel, the frustum's function is to transition the primary flight loads from the rocket's upper stage to the first stage. The frustum is located between the forward skirt extension and the upper stage of the Ares I-X. The frustum will be integrated with the forward skirt and forward skirt extension, which already are in the ARF. That will complete the forward assembly. The assembly then will be moved to the Vehicle Assembly Building for stacking operations, which are scheduled to begin in April. Photo credit: NASA/Kim Shiflett

  1. KSC-2009-1770

    NASA Image and Video Library

    2009-02-21

    CAPE CANAVERAL, Fla. – In the Assembly and Refurbishment Facility, or ARF, at NASA's Kennedy Space Center, an overhead crane lifts the frustum for the Ares I-X test rocket from its transporter. The frustum is the last manufactured section of the Ares I-X. The frustum will be moved from the transporter to supports on the floor. Resembling a giant funnel, the frustum's function is to transition the primary flight loads from the rocket's upper stage to the first stage. The frustum is located between the forward skirt extension and the upper stage of the Ares I-X. The frustum will be integrated with the forward skirt and forward skirt extension, which already are in the ARF. That will complete the forward assembly. The assembly then will be moved to the Vehicle Assembly Building for stacking operations, which are scheduled to begin in April. Photo credit: NASA/Kim Shiflett

  2. The chemical signatures of progressive dehydration stages in subducted serpentinites

    NASA Astrophysics Data System (ADS)

    Pettke, T.; Spandler, C.; Kodolanyi, J.; Scambelluri, M.

    2009-04-01

    Fluids mediate chemical cycling in subduction zones. Nonetheless, the chemistry of serpentinite-dehydration fluids from down-going slabs and their chemical effects on ascent are only very poorly constrained. We report new data on discontinuous dehydration reactions, including the measurement of individual fluid inclusions in prograde minerals from natural occurrences, and one case study tracing the infiltration of serpentinite-derived fluid in mafic eclogite. Together, these studies demonstrate that serpentinite-derived fluids are commonly dilute, but that there may be selected trace element abundances (and ratios ?) that characterize such fluid provenance. Brucite dehydration represents the first relevant liberation of crystal-bound water from serpentinites formed on the ocean floor (ocean floor mantle hydration chemistry is addressed in Kodolanyi et al., this session). Discordant olivine-Ti-clinohumite-antigorite-clinopyroxene-magnetite veins in ca. 2.3 GPa antigorite serpentinites of the Erro Tobbio in the Ligurian Alps, Italy, formed from aqueous, dilute fluids containing Li, Sr, Ba, Rb, Pb as determined on texturally-early fluid inclusions in olivine. This prograde olivine preserves high Ni (1500 - 3000 µg/g) and is identified most readily by elevated Li (1-20 µg/g), B (1-20 µg/g) and Mn contents. Aqueous fluid inclusions in some clinopyroxene (Cpx) of the same veins host variably (sometimes highly) saline fluid inclusions, interpreted to represent the "spent" fluid after formation of hydrous vein minerals (chlorite, antigorite). Vein bulk-rock trace-element concentrations show enrichment in Ti, Ba, Nb, Li, HREE and Cu relative to the wall rocks, accompanied by depletion in Cr. This mostly reflects the mineral transformations (sources / sinks) occurring at this stage of serpentinite dehydration. Antigorite-breakdown is arguably the most prominent water release from down-going slabs. Olivine-orthopyroxene-chlorite rocks at Cerro del Almirez (Spain), recording this dehydration event, contain olivine-hosted polyphase inclusions interpreted to represent fluid inclusions trapped during antigorite breakdown. Preliminary compositional data show enrichments in B, Cs, Pb, Li, Sr, Rb, K, Ba (decreasing order) and depletions in Ca, Ti, La relative to primitive mantle, closely corresponding to the incompatible element pattern of typical island arc lavas. Transfer of such fluids to the melting source of island arc magmas may be critical to developing their distinctive trace element signatures. Omphacite-rich (± garnet, rutile, talc and zircon) veins cutting eclogite (Fe-Ti gabbro protolith, Monviso, W Italian Alps) record serpentinite-derived fluid pathways though the subducted slab at ca. 70 km depth. Although these veins largely formed by local eclogite-derived fluids, they also preserve discrete generations of vein minerals enriched in Mg, Cr, Ni, B, As and Sb, and zircon with elevated Epsilon(Hf) compared to host-rock eclogite zircon. These chemical and isotopic characteristics suggest external fluid input, from serpentinite dehydration. Moreover, distinctive oscillatory or irregular Cr zonations observed in omphacite, garnet and rutile from the veins are interpreted to record episodic fracturing and fluid infiltration over >10 m along transient brittle fractures at high pressures. Our current data suggest that dehydration fluid pervades the rock at the site of liberation, and that episodic fluid escape from the dehydration site may be effectively channelized. This supports growing evidence for highly focused reactive fluid flow through slabs. Robust constraints on the chemical composition and nature of dehydration fluids from serpentinites and how they evolve during ascent may greatly aid in recognizing such features from outcrop to thin-section scales, in turn providing us with more comprehensive sample material to advance our understanding on fluid-mediated cycling in subduction zones. Reference Kodolanyi et al., this session

  3. 35. INTERIOR VIEW TO THE NORTHWEST OF ROOM 152, A ...

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

    35. INTERIOR VIEW TO THE NORTHWEST OF ROOM 152, A FIRST FLOOR CORRIDOR AND VIEWING GALLERY ON THE WEST SIDE OF THE POST-MORTEM CELLS. VIEWING AND WORK STATIONS ARE IN THE EAST WALL. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  4. 49 CFR Appendix B to Part 238 - Test Methods and Performance Criteria for the Flammability and Smoke Emission Characteristics of...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., etc.) shall be designed against acting as passageways for fire and smoke and representative... structural flooring assembly to perform as a barrier against under-vehicle fires. The fire resistance period... Flammability and Smoke Emission Characteristics of Materials Used in Passenger Cars and Locomotive Cabs B...

  5. Commander Young removes CAP from FDF stowage locker on middeck

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Commander Young removes Crew Activity Plans (CAP) from Flight Data File (FD/FDF) modular stowage locker single tray assembly located in forward middeck locker MF28E. Window shade and filter kit on port side bulkhead and potable water tank on middeck floor appear in view. Photo was taken by Pilot Crippen with a 35mm camera.

  6. Fire resistance of engineered wood rim board products.

    Treesearch

    Robert H. White

    2003-01-01

    Engineered wood products, such as oriented strandboard, laminated veneer lumber, and other composite wood products, are being used more often in construction. This includes use as rim boards, which are the components around the perimeter of a floor assembly. This situation has increased the need for information about the fire resistance of these products. In this study...

  7. The School of the Future. Stelco Trend. Number 34 in a Series.

    ERIC Educational Resources Information Center

    Walker, Howard V.; Arthur, E. R.

    Floor plans and illustrations present a simplified building system for an elementary school that can be utilized by any school board. All components for the system can be drawn from existing products and readily integrated with the structure. The component assembly and connections are illustrated in detail. Factory production is utilized to reduce…

  8. The characteristics of rotational slumps and subaqueous translational slab slides of the Lower Murray River, South Australia: do they have any implications for the weak-layer hypothesis?

    NASA Astrophysics Data System (ADS)

    Hubble, Thomas; De Carli, Elyssa; Airey, David; Breakfree 2012-2013, Scientific Parties MV

    2014-05-01

    The peak of the recent prolonged 'Millennium Drought' (1997-2011) triggered an episode of widespread mass failure in the alluvial river-banks of the Lower Murray River in South Australia. Multi-beam surveying of the channel and submerged river-banks between Mannum and Murray Bridge and coring of the bank sediments has been undertaken in sections of the river where large bank failures threatened private housing or public infrastructure. This data demonstrates that the bank materials are soft, horizontally-layered muds and that translational, planar slab-slides have frequently occurred in permanently submerged portions of the Murray's river banks. Despite these riverine features being several orders of magnitude smaller than the translational submarine landslides of the continental margins, the submerged river-bank slides are strikingly similar in their morphology to their submarine equivalents. Intriguingly, the Murray River translational slide failure-surfaces are usually developed as river-floor-parallel features in a manner similar to many submarine landslides which present failure-surfaces that are developed on seafloor-parallel, bedding planes. In contrast however, the Murray's river-bank slides occur on steep slopes (>20o) and their failure surfaces must cut across the horizontal laminations and layering of the muds at a relative high angle which removes the possibility of a weak sediment layer being responsible for the occurrence of these failures. Modelling of the river-bank failures with classical soil mechanics methods and the measured physical properties of the river-bank materials indicates that the failures are probably a consequence of flood-flow scour removing the bank-slope toe in combination with pore-pressure effects related to river-level fluctuation (ie. drawdown). Nevertheless, the Murray's translational slab-slides provide a reliable example of slope-parallel planar failure in muds that does not require a stratigraphic weak layer to explain the occurrence of those failures.

  9. Magmatism during the accretion of the late Archaean Dharwar Craton (South India): sanukitoids and related rocks in their geological context.

    NASA Astrophysics Data System (ADS)

    Moyen, J.-F.; Martin, H.; Jayananda, M.; Peucat, J.-J.

    2003-04-01

    The South Indian Dharwar Craton assembled during the late-Archaean (ca. 2.5 Ga). This event was associated with intense granite genesis and emplacement. Based on petrography and geochemistry, 4 main types of late Archaean granitoids were distinguished: (1) Anatectic granites (and diatexites), formed by partial melting of TTG gneisses; (2) Classical TTGs; (3) Sanukitoids, generated by interaction between slab melts (TTG) and mantle peridotite; (4) The high HFSE Closepet granite, interpreted as derived from partial melting of a mantle metasomatized by slab melts (TTG). While the 3 later groups all are interpreted as resulting from slab melt/mantle wedge interactions, their differences are related to decreasing felsic melt/peridotite ratios during the ascent “slab melts” in the mantle wedge above an active subduction zone. Field data together with geochronology and isotope geochemistry allow to subdivide the Dharwar craton into three main domains: (1) The Western Dharwar Craton (WDC) is an old (3.3 2.9 Ga ), stable continental block with limited amounts of 2.5 Ga old anatectic granites. (2) The Eastern Dharwar Craton (EDC) is subdivided into two parts: (2a) West of Kolar Schist Belt, a region of 3.0-2.7 Ga old basement intruded by 2.5 Ga old anatectic granites; (2b) East of Kolar, an area featuring mainly 2.5 Ga old diatexites and granites, derived of partial melting of a newly accreted TTG crust. Anatectic granites are ubiquitous, and late in the cratonic evolution; they witnessed generalized melting of a juvenile crust. In contrast, deep-originated granites emplaced before this melting and are restricted to the boundaries between the blocks. This structure of distinct terranes separated by narrow bands operating as channels for deep-originated magmas provides independent evidences for a two-stage evolution: an arc accretion context for the TTG, sanukitoids and related rocks, immediately followed by high temperature reworking of the newly accreted craton, yielding diatexites and anatectic granites. From West to East, granitoids emplaced during the subduction stage evidence increasing slab-melt/peridotite interactions, from Closepet granite to TTG gneisses East of Kolar. These features are consistent with a model of westward subduction/accretion against a stable cratonic nucleus: partial melting along the subducting slab takes place at deeper and deeper levels from East to West, thus resulting in increasing melt/mantle interactions. Sanukitoids and Closepet type granites thus appear to be related to slab melt/mantle wedge interactions similar to those responsible for the secular evolution of TTG (Martin and Moyen, this session), but with still lower melt/peridotite ratios.

  10. The Two Subduction Zones of the Southern Caribbean: Lithosphere Tearing and Continental Margin Recycling in the East, Flat Slab Subduction and Laramide-Style Uplifts in the West

    NASA Astrophysics Data System (ADS)

    Levander, A.; Bezada, M. J.; Niu, F.; Schmitz, M.

    2015-12-01

    The southern Caribbean plate boundary is a complex strike-slip fault system bounded by oppositely vergent subduction zones, the Antilles subduction zone in the east, and a currently locked Caribbean-South American subduction zone in the west (Bilham and Mencin, 2013). Finite-frequency teleseismic P-wave tomography images both the Atlanic (ATL) and the Caribbean (CAR) plates subducting steeply in opposite directions to transition zone depths under northern South America. Ps receiver functions show a depressed 660 discontinuity and thickened transition zone associated with each subducting plate. In the east the oceanic (ATL) part of the South American (SA) plate subducts westward beneath the CAR, initiating the El Pilar-San Sebastian strike slip system, a subduction-transform edge propagator (STEP) fault (Govers and Wortel, 2005). The point at which the ATL tears away from SA as it descends into the mantle is evidenced by the Paria cluster seismicity at depths of 60-110 km (Russo et al, 1993). Body wave tomography and lithosphere-asthenosphere boundary (LAB) thickness determined from Sp and Ps receiver functions and Rayleigh waves suggest that the descending ATL also viscously removes the bottom third to half of the SA continental margin lithospheric mantle as it descends. This has left thinned continental lithosphere under northern SA in the wake of the eastward migrating Antilles subduction zone. The thinned lithosphere occupies ~70% of the length of the El Pilar-San Sebastian fault system, from ~64oW to ~69oW, and extends inland several hundred kilometers. In northwestern SA the CAR subducts east-southeast at low angle under northern Colombia and western Venezuela. The subducting CAR is at least 200 km wide, extending from northernmost Colombia as far south as the Bucaramanga nest seismicity. The CAR descends steeply under Lake Maracaibo and the Merida Andes. This flat slab is associated with three Neogene basement cored, Laramide-style uplifts: the Santa Marta block, the Perija Range, and the Merida Andes (Kellogg and Bonini, 1982). The steep descent of the CAR under Maracaibo implies that the CAR plate is torn somewhere between the Merida Andes and the Caribbean Sea, where it forms the ocean floor. An upcoming broadband seismic experiment will examine the CAR flat slab and the suspected slab tear in detail.

  11. Characterizing wet slab and glide slab avalanche occurrence along the Going-to-the-Sun Road, Glacier National Park, Montana, USA

    USGS Publications Warehouse

    Peitzsch, Erich H.; Hendrikx, Jordy; Fagre, Daniel B.; Reardon, Blase

    2010-01-01

    Wet slab and glide slab snow avalanches are dangerous and yet can be particularly difficult to predict. Both wet slab and glide slab avalanches are thought to depend upon free water moving through the snowpack but are driven by different processes. In Glacier National Park, Montana, both types of avalanches can occur in the same year and affect the Going-to-the-Sun Road (GTSR). Both wet slab and glide slab avalanches along the GTSR from 2003-2010 are investigated. Meteorological data from two high-elevation weather stations and one SNOTEL site are used in conjunction with an avalanche database and snowpit profiles. These data were used to characterize years when only glide slab avalanches occurred and those years when both glide slab and wet slab avalanches occurred. Results of 168 glide slab and 57 wet slab avalanches along the GTSR suggest both types of avalanche occurrence depend on sustained warming periods with intense solar radiation (or rain on snow) to produce free water in the snowpack. Differences in temperature and net radiation metrics between wet slab and glide slab avalanches emerge as one moves from one day to seven days prior to avalanche occurrence. On average, a more rapid warming precedes wet slab avalanche occurrence. Glide slab and wet slab avalanches require a similar amount of net radiation. Wet slab avalanches do not occur every year, while glide slab avalanches occur annually. These results aim to enhance understanding of the required meteorological conditions for wet slab and glide slab avalanches and aid in improved wet snow avalanche forecasting.

  12. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paul Higley; J. Robert Woolsey; Ralph Goodman

    A Consortium, designed to assemble leaders in gas hydrates research, has been established at the University of Mississippi's Center for Marine Resources and Environmental Technology, CMRET. The primary objective of the group is to design and emplace a remote monitoring station on the sea floor in the northern Gulf of Mexico by the year 2005, in an area where gas hydrates are known to be present at, or just below, the sea floor. This mission necessitates assembling a station that will monitor physical and chemical parameters of the sea water and sea floor sediments on a more-or-less continuous basis overmore » an extended period of time. Development of the station allows for the possibility of expanding its capabilities to include biological monitoring, as a means of assessing environmental health. Establishment of the Consortium has succeeded in fulfilling the critical need to coordinate activities, avoid redundancies and communicate effectively among researchers in this relatively new research arena. Complementary expertise, both scientific and technical, has been assembled to promote innovative research methods and construct necessary instrumentation. Noteworthy achievements one year into the extended life of this cooperative agreement include: (1) Progress on the vertical line array (VLA) of sensors: (1a) Repair attempts of the VLA cable damaged in the October >1000m water depth deployment failed; a new design has been tested successfully. (1b) The acoustic modem damaged in the October deployment was repaired successfully. (1c) Additional acoustic modems with greater depth rating and the appropriate surface communications units have been purchased. (1d) The VLA computer system is being modified for real time communications to the surface vessel using radio telemetry and fiber optic cable. (1e) Positioning sensors--including compass and tilt sensors--were completed and tested. (1f) One of the VLAs has been redesigned to collect near sea floor geochemical data. (2) Progress on the Sea Floor Probe: (2a) With the Consortium's decision to divorce its activities from those of the Joint Industries Program (JIP), due to the JIP's selection of a site in 1300m of water, the Sea Floor Probe (SFP) system was revived as a means to emplace arrays in the shallow subsurface until arrangements can be made for boreholes at >1000m water depth. (2b) The SFP penetrometer has been designed and construction begun. (2c) The SFP geophysical and pore-fluid probes have been designed. (3) Progress on the Acoustic Systems for Monitoring Gas Hydrates: (3a) Video recordings of bubbles emitted from a seep in Mississippi Canyon have been analyzed for effects of currents and temperature changes. (3b) Several acoustic monitoring system concepts have been evaluated for their appropriateness to MC118, i.e., on the deep sea floor. (3c) A mock-up system was built but was rejected as too impractical for deployment on the sea floor. (4) Progress on the Electromagnetic Bubble Detector and Counter: (4a) Laboratory tests were performed using bubbles of different sizes in waters of different salinities to test the sensitivity of the. Differences were detected satisfactorily. (4b) The system was field tested, first at the dock and then at the shallow water test site at Cape Lookout Bight where methane bubbles from the sea floor, naturally, in 10m water depth. The system successfully detected peaks in bubbling as spike decreases in conductivity. (5) Progress on the Mid-Infrared Sensor for Continuous Methane Monitoring: (5a) Modeling and design of an optics platform complementary to the constructed electronics platform for successful incorporation into ''sphereIR'' continues. AutoCAD design and manual construction of mounting pieces for major optical components have been completed. (5b) Initial design concepts for IR-ATR sensor probe geometries have been established and evaluated. Initial evaluations of a horizontal ATR (HATR) sensing probe with fiber optic guiding light have been performed and validate the design concept as a potentially viable deep sea sensing probe. (5c) Ray tracing simulations have been performed to evaluate light propagation through HATR elements to facilitate the optimal design of both the sensing probe and optical configuration of ''sphereIR''. (5d) The highly permeable polymer, polydimethylsiloxane (PDMS), was investigated as a potential methane enrichment membrane for IR-ATR sensors. (6) Progress on the Seismo-acoustic Characterization of Sea Floor Properties and Processes at the Hydrate Monitoring Station: (6a) All system components underwent extensive testing in preparation for determining sea floor acoustic reflection responses at the Gas Hydrate Monitoring Station. (6b) Final testing and commissioning have been completed.« less

  13. Constraints on the Geometry of the Farallon Slab from the Joint Interpretation of All Available Imaging Results from the Earthscope USArray Deployment in the Lower 48 States

    NASA Astrophysics Data System (ADS)

    Esker, A.; Pavlis, G. L.

    2017-12-01

    We assembled all available seismic tomography models distributed through the IRIS DMC and other sources. We combined these images with our own results using 3D plane wave migration of P to S conversion data derived from the USArray data set and other broadband seismic stations in the lower 48 states. All the tomography models were converted into SEGY format and interpolated onto a regular grid in a UTM reference frame. That innovation makes joint interpretation feasible using a seismic interpretation software (Petrel) because we treat both the tomography models and scattered wave image results as if they were 3D seismic reflection data. The careful designed interface of a modern exploration package makes exploring a range of interpretation packages much faster and allowed us to produce a more comprehensive interpretation of all available data. The tomography models are nearly an order of magnitude smoother than the scattered wave images, so we use the tomography models as a cross-validation in interpretation unless the scattered wave images are ambiguous. The focus of this study is testing a conjecture in an earlier paper (Pavlis, 2011) for the presence of a single continuous horizon interpreted as the top of the Farallon Slab. As in the previous paper we constrained the western edge of this surface with the location of Cascadia trench as well as a virtual edge from a back projection of the Mendocino triple junction using Pacific-North America motion over the past 30 Ma. We also simulated crustal multiple effects on the plane wave migration results using crustal geometry estimates produced by the Earthscope Automated Receiver Survey (EARS). This confirmed the scattered wave images were not reliable in the upper mantle at depths shallower than 200 km due to contamination by crustal multiples. Most tomography models show a steep dip in the slab immediately east of the volcanic arc and our surface follows the average geometry defined by a visual comparison of all the models. In eastern Oregon and northern Nevada the tomography models consistently show a general flattening of the slab over the 410 km discontinuity. A consistent horizon is observed in the most recent plane wave imaging and at we use that horizon to define the top of slab there. Our interpretations also confirmed a sharp increase in dip of the slab in eastern Wyoming and Montana.

  14. Novel Layered Supercell Structure from Bi 2AlMnO 6 for Multifunctionalities

    DOE PAGES

    Li, Leigang; Boullay, Philippe; Lu, Ping; ...

    2017-10-02

    Layered materials, e.g., graphene and transition metal (di)chalcogenides, holding great promises in nanoscale device applications have been extensively studied in fundamental chemistry, solid state physics and materials research areas. In parallel, layered oxides (e.g., Aurivillius and Ruddlesden–Popper phases) present an attractive class of materials both because of their rich physics behind and potential device applications. In this work, we report a novel layered oxide material with self-assembled layered supercell structure consisting of two mismatch-layered sublattices of [Bi 3O 3+δ] and [MO 2] 1.84 (M = Al/Mn, simply named BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made ofmore » a three-layer-thick Bi–O slab and a one-layer-thick Al/Mn–O octahedra slab in the out-of-plane direction. Strong room-temperature ferromagnetic and piezoelectric responses as well as anisotropic optical property have been demonstrated with great potentials in various device applications. Furthermore, the realization of the novel BAMO layered supercell structure in this work has paved an avenue toward exploring and designing new materials with multifunctionalities.« less

  15. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Leigang; Boullay, Philippe; Lu, Ping

    Layered materials, e.g., graphene and transition metal (di)chalcogenides, holding great promises in nanoscale device applications have been extensively studied in fundamental chemistry, solid state physics and materials research areas. In parallel, layered oxides (e.g., Aurivillius and Ruddlesden–Popper phases) present an attractive class of materials both because of their rich physics behind and potential device applications. In this work, we report a novel layered oxide material with self-assembled layered supercell structure consisting of two mismatch-layered sublattices of [Bi 3O 3+δ] and [MO 2] 1.84 (M = Al/Mn, simply named BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made ofmore » a three-layer-thick Bi–O slab and a one-layer-thick Al/Mn–O octahedra slab in the out-of-plane direction. Strong room-temperature ferromagnetic and piezoelectric responses as well as anisotropic optical property have been demonstrated with great potentials in various device applications. Furthermore, the realization of the novel BAMO layered supercell structure in this work has paved an avenue toward exploring and designing new materials with multifunctionalities.« less

  16. 34. INTERIOR VIEW TO THE NORTH OF ROOMS 143 AND ...

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

    34. INTERIOR VIEW TO THE NORTH OF ROOMS 143 AND 150, A FIRST FLOOR CORRIDOR AND VIEWING GALLERY ON THE EAST SIDE OF THE POST-MORTEM CELLS. VIEWING AND WORK STATIONS ARE IN THE NORTH AND WEST WALLS. - Nevada Test Site, Reactor Maintenance Assembly & Dissassembly Facility, Area 25, Jackass Flats, Junction of Roads F & G, Mercury, Nye County, NV

  17. 14. DETAIL OF CONNECTIONS AT THE BOTTOM OF A POST ...

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

    14. DETAIL OF CONNECTIONS AT THE BOTTOM OF A POST IN THE WEST TRUSS, SHOWING THE ASSEMBLY OF LOWER CHORD AND DIAGONAL EYE BOLTS AND THE SUSPENSION OF A FLOOR BEAM FROM THE POST BY A U-BOLT; VIEW FROM SOUTH BANK. - Mitchell's Mill Bridge, Spanning Winter's Run on Carrs Mill Road, west of Bel Air, Bel Air, Harford County, MD

  18. 49 CFR 571.209 - Standard No. 209; Seat belt assemblies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... anchorage nuts, plates, or washers, need not have such hardware, but shall have 7/16-20 UNF-2A or 1/2-13UNC... plates or washers furnished for universal floor, installations shall be of steel, free from burrs and... 2580 mm2 in projected area. The distance between any edge of the plate and the edge of the bolt hole...

  19. In situ Observation of Direct Electron Transfer Reaction of Cytochrome c Immobilized on ITO Electrode Modified with 11-{2-[2-(2-Methoxyethoxy)ethoxy]ethoxy}undecylphosphonic Acid Self-assembled Monolayer Film by Electrochemical Slab Optical Waveguide Spectroscopy.

    PubMed

    Matsuda, Naoki; Okabe, Hirotaka; Omura, Ayako; Nakano, Miki; Miyake, Koji

    2017-01-01

    To immobilize cytochrome c (cyt.c) on an ITO electrode while keeping its direct electron transfer (DET) functionality, the ITO electrode surface was modified with 11-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}undecylphosphonic acid (CH 3 O (CH 2 CH 2 O) 3 C 11 H 22 PO(OH) 2 , M-EG 3 -UPA) self-assembled monolayer (SAM) film. After a 100-times washing process to exchange a phosphate buffer saline solution surrounding cyt.c and ITO electrode to a fresh one, an in situ observation of visible absorption spectral change with slab optical waveguide (SOWG) spectroscopy showed that 87.7% of the cyt.c adsorbed on the M-EG 3 -UPA modified ITO electrode remained on the ITO electrode. The SOWG absorption spectra corresponding to oxidized and reduced cyt.c were observed with setting the ITO electrode potential at 0.3 and -0.3 V vs. Ag/AgCl, respectively, while probing the DET reaction between cyt.c and ITO electrode occurred. The amount of cyt.c was evaluated to be about 19.4% of a monolayer coverage based on the coulomb amount in oxidation and reduction peaks on cyclic voltammetry (CV) data. The CV peak current maintained to be 83.4% compared with the initial value for a M-EG 3 -UPA modified ITO electrode after 60 min continuous scan with 0.1 V/s between 0.3 and -0.3 V vs. Ag/AgCl.

  20. The subresolution DaTSCAN phantom: a cost-effective, flexible alternative to traditional phantom technology.

    PubMed

    Taylor, Jonathan C; Vennart, Nicholas; Negus, Ian; Holmes, Robin; Bandmann, Oliver; Lo, Christine; Fenner, John

    2018-03-01

    The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer. The paper sheets and attenuating slabs are interleaved before scanning. Use of thin layers ensures that they cannot be individually resolved on reconstructed images. An investigation was carried out to demonstrate the performance of such a phantom in producing simplified I-FP-CIT uptake patterns. Single photon emission computed tomography imaging was carried out on an assembled phantom designed to mimic a healthy patient. Striatal binding ratio results and linear striatal dimensions were calculated from the reconstructed data and compared with that of 22 clinical patients without evidence of Parkinsonian syndrome, determined from clinical follow-up. Striatal binding ratio results for the fully assembled phantom were: 3.1, 3.3, 2.9 and 2.6 for the right caudate, left caudate, right putamen and right caudate, respectively. All were within two SDs of results derived from a cohort of clinical patients. Medial-lateral and anterior-posterior dimensions of the simulated striata were also within the range of values seen in clinical data. This work provides the foundation for the generation of a range of more clinically realistic, physical phantoms.

  1. Corporate ergonomics programme at automobiles Peugeot-Sochaux.

    PubMed

    Moreau, M

    2003-01-01

    An ergonomic assessment tool for design procedures, exclusive to Peugeot-Citroën, called ECM, was developed and applied at the design stage by method technicians in the 1990s. It generates data, which are followed up by the project leader of a new model and ergonomists until two years before each launch. During this time, vehicle design is subject to modification, to adapt to ergonomic demands. Simplified methods (DACORS and METEO) were also developed to assess workstations on the shop floor in trim and final plants. Assessments were used to grade the workstations into four profiles linked to physical and static requirements. Production technicians are responsible for the application of these local methods on the shop floor. The management of these centres aimed to reduce the risks of musculoskeletal disorders by reduced heavy profiles of these stations. New cases of musculoskeletal disorders, surveyed by the company doctor among workers on the assembly lines had decreased since 1996. In 1999, the incidence increased again, despite the pursuit of ergonomic methods. This increase in musculoskeletal disorders was above all linked to a major reorganisation of work conditions, including a reduction in the cycle time on the assembly line, and to a move into a new workshop.

  2. KSC-2009-2796

    NASA Image and Video Library

    2009-04-20

    CAPE CANAVERAL, Fla. –– In High Bay 4 of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, the yellow framework at left, nicknamed the "birdcage," is lifted high above the floor for a fit check with the Crew Module, or CM, and Launch Abort System, or LAS, assembly nearby for the Ares I-X rocket. Ares I-X is the flight test for the Ares I. The I-X flight will provide NASA an early opportunity to test and prove hardware, facilities and ground operations associated with Ares I. The launch of the 327-foot-tall, full-scale Ares I-X is targeted for July 2009. Photo credit: NASA/Jack Pfaller

  3. Mobile Centers For Secondary Power Distribution

    NASA Technical Reports Server (NTRS)

    Mears, Robert L.

    1990-01-01

    Concept for distribution of 60-Hz ac power in large building devoted to assembly and testing of equipment improves safety, reduces number of outlets and lengthy cables, and readily accommodates frequent changes in operations and configuration. Power from floor recess fed via unobtrusive cable to portable power management center. A cart containing variety of outlets and circuit breakers, wheeled to convenient location near equipment to be assembled or tested. Power distribution system presents larger range of operational configurations than fixed location. Meets tighter standards to feed computers and delicate instruments. Industrial-grade power suitable for power tools and other hardware. Three-phase and single-phase outlets available from each.

  4. Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Negus, Ian S.; Holmes, Robin B.; Thorne, Gareth C.

    Purpose: To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. Methods: A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain bymore » adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding {sup 99m}Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Results: Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. Conclusions: The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable for use in PET.« less

  5. Short-Term Monitoring Results for Advanced New Construction Test House -- Roseville, California

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stecher, D.; Brozyna, K.; Imm, C.

    2013-09-01

    A builder (K. Hovnanian Homes), design consultant, and trades collaborated to identify a systems integrated measures package for a 2,253-ft2 slab-on-grade ranch house to achieve a modeled energy savings of 60% with respect to the Building America House Simulation Protocols (Hendron, R. and Engebrecht, C. 'Building America House Simulation Protocols.' Golden, CO: National Renewable EnergyLaboratory, 2010) while minimizing construction costs and without requiring changes to the drawing that would impact local code or zoning approval. The key building improvements were applying R-10 insulation to the slab edge, increasing exterior wall cavity insulation from R-13 to R-15, and increasing attic insulationmore » from R-30 to R-38. Also, the air handling unit was relocated from the attic toconditioned space, and ductwork was relocated along the attic floor with an insulated bulkhead built above it. Short-term testing results showed that duct air leakage was low due to short duct runs and the placement of ductwork in conditioned space. However, during commissioning, the lack of access for servicing the ductwork and dampers in the bulkhead area prevented retroactive balancing ofindividual branches, resulting in significant differences between specified and measured airflow values for some duct runs. Thermal imaging results performed on the house when operating in both heating and cooling modes validated historic stratification issues of ceiling supply registers with high supply air temperatures. Long-term monitoring results will be detailed in a future report.« less

  6. Precast concrete unit assessment through GPR survey and FDTD modelling

    NASA Astrophysics Data System (ADS)

    Campo, Davide

    2017-04-01

    Precast concrete elements are widely used within United Kingdom house building offering ease in assembly and added values as structural integrity, sound and thermal insulation; most common concrete components include walls, beams, floors, panels, lintels, stairs, etc. The lack of respect of the manufacturer instruction during assembling, however, may induce cracking and short/long term loss of bearing capacity. GPR is a well-established not destructive technique employed in the assessment of structural elements because of real-time imaging, quickness of data collecting and ability to discriminate finest structural details. In this work, GPR has been used to investigate two different precast elements: precast reinforced concrete planks constituting the roof slab of a school and precast wood-cement blocks with insulation material pre-fitted used to build a perimeter wall of a private building. Visible cracks affected both constructions. For the assessment surveys, a GSSI 2.0 GHz GPR antenna has been used because of the high resolution required and the small size of the antenna case (155 by 90 by 105mm) enabling scanning up to 45mm from any obstruction. Finite Difference Time Domain (FDTD) numerical modelling was also performed to build a scenario of the expected GPR signal response for a preliminary real-time interpretation and to help solve uncertainties due to complex reflection patterns: simulated radargrams were built using Reflex Software v. 8.2, reproducing the same GPR pulse used for the surveys in terms of wavelet, nominal frequency, sample frequency and time window. Model geometries were derived from the design projects available both for the planks and the blocks; the electromagnetic properties of the materials (concrete, reinforcing bars, air-filled void, insulation and wooden concrete) were inferred from both values reported in literature and a preliminary interpretation of radargrams where internal layer interfaces were clearly recognizable and univocally interpretable. Simulated and real radargrams comparison demonstrated that, in both cases, manufacturer instructions were not fully respected and confirmed GPR as a fast and effective structural assessment technique with the support of FDTD modelling as data interpretation validating method when complex reflection patterns are observed. GPR findings will be then used to address the intrusive coring necessary to evaluate the compressive strength of the concrete and, in synergy with the intrusive survey results, to plan properly corrective actions to ensure the stability of the structures and guarantee the usability.

  7. SUPPORT OF GULF OF MEXICO HYDRATE RESEARCH CONSORTIUM: ACTIVITIES TO SUPPORT ESTABLISHMENT OF A SEA FLOOR MONITORING STATION PROJECT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paul Higley; J. Robert Woolsey; Ralph Goodman

    The Gulf of Mexico Hydrates Research Consortium (GOM-HRC) was established in 1999 to assemble leaders in gas hydrates research. The primary objective of the group has been to design and emplace a remote monitoring station or sea floor observatory (MS/SFO) on the sea floor in the northern Gulf of Mexico by the year 2005, in an area where gas hydrates are known to be present at, or just below, the sea floor. This mission, although unavoidably delayed by hurricanes and other disturbances, necessitates assembling a station that will monitor physical and chemical parameters of the sea water and sea floormore » sediments on a more-or-less continuous basis over an extended period of time. Development of the station has always included the possibility of expanding its capabilities to include biological monitoring, as a means of assessing environmental health. This possibility has recently achieved reality via the National Institute for Undersea Science and Technology's (NIUST) solicitation for proposals for research to be conducted at the MS/SFO. Establishment of the Consortium has succeeded in fulfilling the critical need to coordinate activities, avoid redundancies and communicate effectively among researchers in the arena of gas hydrates research. Complementary expertise, both scientific and technical, has been assembled to promote innovative research methods and construct necessary instrumentation. The observatory has achieved a microbial dimension in addition to the geophysical and geochemical components it had already included. Initial components of the observatory, a probe that collects pore-fluid samples and another that records sea floor temperatures, were deployed in Mississippi Canyon 118 in May of 2005. Follow-up deployments, planned for fall 2005, have had to be postponed and the use of the vessel M/V Ocean Quest and its two manned submersibles sacrificed due to the catastrophic effects of Hurricane Katrina (and later, Rita) on the Gulf Coast. Every effort is being made to locate and retain the services of a replacement vessel and submersibles or Remotely Operated Vehicles (ROVs) but these efforts have been fruitless due to the demand for these resources in the tremendous recovery effort being made in the Gulf area. Station/observatory completion, anticipated for 2007, will likely be delayed by at least one year. The seafloor monitoring station/observatory is funded approximately equally by three federal Agencies: Minerals Management Services (MMS) of the Department of the Interior (DOI), National Energy Technology Laboratory (NETL) of the Department of Energy (DOE), and the National Institute for Undersea Science and Technology (NIUST), an agency of the National Oceanographic and Atmospheric Administration (NOAA). Subcontractors with FY03 funding fulfilled their technical reporting requirements in the previous report (41628R10). Only unresolved matching funds issues remain and will be addressed in the report of the University of Mississippi's Office of Research and Sponsored Programs.« less

  8. Modular, security enclosure and method of assembly

    DOEpatents

    Linker, Kevin L.; Moyer, John W.

    1995-01-01

    A transportable, reusable rapidly assembled and disassembled, resizable modular, security enclosure utilizes a stepped panel construction. Each panel has an inner portion and an outer portion which form joints. A plurality of channels can be affixed to selected joints of the panels. Panels can be affixed to a base member and then affixed to one another by the use of elongated pins extending through the channel joints. Alternatively, the base member can be omitted and the panels themselves can be used as the floor of the enclosure. The pins will extend generally parallel to the joint in which they are located. These elongated pins are readily inserted into and removable from the channels in a predetermined sequence to allow assembly and disassembly of the enclosure. A door constructed from panels is used to close the opening to the enclosure.

  9. Direct Measurements of the Evolution and Impact of Sediment Density Flows as they Pass Through Monterey Submarine Canyon, Offshore California

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Talling, P.; Maier, K. L.; Parsons, D. R.; Xu, J.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.; Anderson, K.; Barry, J.; Chaffey, M. R.; O'Reilly, T. C.; Rosenberger, K. J.; Gales, J. A.; McGann, M.; McCann, M. P.; Simmons, S.; Sumner, E.

    2017-12-01

    Sediment density flows flushing through submarine canyons carry globally significant amounts of material into the deep sea to form many of the largest sediment accumulations on Earth. Despite their global significance, these flows remain poorly understood because they have rarely been directly measured. Here we provide an initial overview of the recently completed Coordinated Canyon Experiment (CCE), which was undertaken specifically to provide detailed measurements of sediment density flows and their impact on seafloor morphology and sedimentology. No previous study has deployed as extensive an array of monitoring sensors along a turbidity current pathway. During the 18 months of the CCE, at least 15 sediment density flows were recorded within the axis of Monterey Canyon. Because no external triggers (i.e., earthquakes or floods) correlate with these flows, they must have originated as failures in the canyon floor or canyon flanks. Three flows ignited and ran out for > 50 km from water depths of <200 to >1,860 m, reaching velocities up to 8.1 m/s. The rest of the flows died out within the array. During these events, large objects on or in the canyon floor were displaced substantial distances downslope, including a 7.1 km downslope movement of an entire mooring; a 4.6 km displacement of an 860 kg instrument frame followed by repeated down canyon displacements of this same frame after it was entombed in sediment; and multiple depth changes of man-made boulders containing acceleration and pressure sensors. During this same time interval the canyon floor was mapped six times with autonomous underwater vehicles covering the canyon thalweg at the upper and lower end of the instrument array (200-540 and 1350-1880 m water depths). The repeated mapping surveys reveal that flows caused +3 to -3 m bathymetric changes within a continuous clearly defined 200 m wide swath running along the canyon axis in <200 to >540 m water depth. This study shows that sediment density flows caused massive remolding of thick sections of the canyon floor in <540 m water depth as a consequence of displacement or fluidization of entire slabs of the seabed during these events.

  10. Solar heating and hot water system installed at Saint Louis, Missouri

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The solar heating and hot water system installed at the William Tao & Associates, Inc., office building in St. Louis, Missouri is described, including maintenance and construction problems, final drawings, system requirements, and manufacturer's component data. The solar system was designed to provide 50 percent of the hot water requirements and 45 percent of the space heating needs for a 900 sq ft office space and drafting room. The solar facility has 252 sq ft of glass tube concentrator collectors and a 1000 gallon steel storage tank buried below a concrete slab floor. Freeze protection is provided by a propylene glycol/water mixture in the collector loop. The collectors are roof mounted on a variable tilt array which is adjusted seasonally and is connected to the solar thermal storage tank by a tube-in-shell heat exchanger. Incoming city water is preheated through the solar energy thermal storage tank.

  11. SUPPORT OF GULF OF MEXICO HYDRATE RESEARCH CONSORTIUM: ACTIVITIES TO SUPPORT ESTABLISHMENT OF A SEA FLOOR MONITORING STATION PROJECT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paul Higley; J. Robert Woolsey; Ralph Goodman

    2005-08-01

    A Consortium, designed to assemble leaders in gas hydrates research, has been established at the University of Mississippi's Center for Marine Resources and Environmental Technology, CMRET. The primary objective of the group is to design and emplace a remote monitoring station on the sea floor in the northern Gulf of Mexico by the year 2005, in an area where gas hydrates are known to be present at, or just below, the sea floor. This mission necessitates assembling a station that will monitor physical and chemical parameters of the sea water and sea floor sediments on a more-or-less continuous basis overmore » an extended period of time. Development of the station allows for the possibility of expanding its capabilities to include biological monitoring, as a means of assessing environmental health. Establishment of the Consortium has succeeded in fulfilling the critical need to coordinate activities, avoid redundancies and communicate effectively among researchers in this relatively new research arena. Complementary expertise, both scientific and technical, has been assembled to innovate research methods and construct necessary instrumentation. A year into the life of this cooperative agreement, we note the following achievements: (1) Progress on the vertical line array (VLA) of sensors: (A) Software and hardware upgrades to the data logger for the prototype vertical line array, including enhanced programmable gains, increased sampling rates, improved surface communications, (B) Cabling upgrade to allow installation of positioning sensors, (C) Adaptation of SDI's Angulate program to use acoustic slant ranges and DGPS data to compute and map the bottom location of the vertical array, (D) Progress in T''0'' delay and timing issues for improved control in data recording, (E) Successful deployment and recovery of the VLA twice during an October, 2003 cruise, once in 830m water, once in 1305m water, (F) Data collection and recovery from the DATS data logger, (G) Sufficient energy supply and normal functioning of the pressure compensated battery even following recharge after the first deployment, (H) Survival of the acoustic modem following both deployments though it was found to have developed a slow leak through the transducer following the second deployment due, presumably, to deployment in excess of 300m beyond its rating. (2) Progress on the Sea Floor Probe: (A) The Sea Floor Probe and its delivery system, the Multipurpose sled have been completed, (B) The probe has been modified to penetrate the <1m blanket of hemipelagic ooze at the water/sea floor interface to provide the necessary coupling of the accelerometer with the denser underlying sediments, (C) The MPS has been adapted to serve as an energy source for both p- and s-wave studies at the station as well as to deploy the horizontal line arrays and the SFP. (3) Progress on the Electromagnetic Bubble Detector and Counter: (A) Components for the prototype have been assembled, including a dedicated microcomputer to control power, readout and logging of the data, all at an acceptable speed, (B) The prototype has been constructed and preliminary data collected, (C) The construction of the field system is underway. (4) Progress on the Acoustic Systems for Monitoring Gas Hydrates: (A) Video recordings of bubbles emitted from a seep in Mississippi Canyon have been made from a submersible dive and the bubbles analyzed with respect to their size, number, and rise rate. These measurements have been used to determine the parameters to build the system capable of measuring gas escaping at the site of the monitoring station, (B) Laboratory tests performed using the project prototype have produced a conductivity data set that is being used to refine parameters of the field model. (5) Progress on the Mid-Infrared Sensor for Continuous Methane Monitoring: (A) Preliminary designs of mounting pieces for electrical components of ''sphereIR'' have been completed using AutoCAD software, (B) The preliminary design of an electronics baseplate has been completed and aided in the optimization of positioning electrical components inside the instrument housing, (C) First spectroscopic investigations of the highly permeable polymer, poly(trimethylsilyl)propyne (PTMSP), as a potential sensing membrane for methane, have commenced, (D) High-pressure multireflection ATR measurements were continued during this project period to investigate the potential influences of hydrostatic pressure on sensing principles and data evaluation strategies. (6) Progress on the Seismo-acoustic Characterization of Sea Floor Properties and Processes at the Hydrate Monitoring Station: (A) work has concentrated on the design and building of the hardware, bench testing and preliminary field trials, (B) development work to extend the capability of the electronics to allow remote operation on the seabed for up to 3 months at a time done.« less

  12. Constraints of subducted slab geometries on trench migration and subduction velocities: flat slabs and slab curtains in the mantle under Asia

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Renqi, L.; Lin, C.; Kanda, R. V.

    2013-12-01

    The past locations, shapes and polarity of subduction trenches provide first-order constraints for plate tectonic reconstructions. Analogue and numerical models of subduction zones suggest that relative subducting (Vs) and overriding (Vor) plate velocities may strongly influence final subducted slab geometries. Here we have mapped the 3D geometries of subducted slabs in the upper and lower mantle of Asia from global seismic tomography. We have incorporated these slabs into plate tectonic models, which allows us to infer the subducting and overriding plate velocities. We describe two distinct slab geometry styles, ';flat slabs' and ';slab curtains', and show their implications for paleo-trench positions and subduction geometries in plate tectonic reconstructions. When compared to analogue and numerical models, the mapped slab styles show similarities to modeled slabs that occupy very different locations within Vs:Vor parameter space. ';Flat slabs' include large swaths of sub-horizontal slabs in the lower mantle that underlie the well-known northward paths of India and Australia from Eastern Gondwana, viewed in a moving hotspot reference. At India the flat slabs account for a significant proportion of the predicted lost Ceno-Tethys Ocean since ~100 Ma, whereas at Australia they record the existence of a major 8000km by 2500-3000km ocean that existed at ~43 Ma between East Asia, the Pacific and Australia. Plate reconstructions incorporating the slab constraints imply these flat slab geometries were generated when continent overran oceanic lithosphere to produce rapid trench retreat, or in other words, when subducting and overriding velocities were equal (i.e. Vs ~ Vor). ';Slab curtains' include subvertical Pacific slabs near the Izu-Bonin and Marianas trenches that extend from the surface down to 1500 km in the lower mantle and are 400 to 500 km thick. Reconstructed slab lengths were assessed from tomographic volumes calculated at serial cross-sections. The ';slab curtain' geometry and restored slab lengths indicate a nearly stationary Pacific trench since ~43 Ma. In contrast to the flat slabs, here the reconstructed subduction zone had large subducting plate velocities relative to very small overriding plate velocities (i.e. Vs >> Vor). In addition to flat slabs and slab curtains, we also find other less widespread local subduction settings that lie at other locations in Vs:Vor parameter space or involved other processes. Slabs were mapped using Gocad software. Mapped slabs were restored to a spherical model Earth surface by two approaches: unfolding (i.e. piecewise flattening) to minimize shape and area distortions, and by evaluated mapped slab volumes. Gplates software was used to integrate the mapped slabs with plate tectonic reconstructions.

  13. Musculoskeletal disorder risk during automotive assembly: current vs. seated

    PubMed Central

    Ferguson, Sue A.; Marras, William S.; Allread, W. Gary; Knapik, Gregory G.; Splittstoesser, Riley E.

    2013-01-01

    Musculoskeletal disorder risk was assessed during automotive assembly processes. The risk associated with current assembly processes was compared to using a cantilever chair intervention. Spine loads and normalized shoulder muscle activity were evaluated during assembly in eight regions of the vehicle. Eight interior cabin regions of the vehicle were classified by reach distance, height from vehicle floor and front to back. The cantilever chair intervention tool was most effective in the far reach regions regardless of the height. In the front far reach regions both spine loads and normalized shoulder muscle activity levels were reduced. In the middle and close reach regions spine loads were reduced, however, shoulder muscle activity was not, thus an additional intervention would be necessary to reduce shoulder risk. In the back far reach region, spine loads were not significantly different between the current and cantilever chair conditions. Thus, the effectiveness of the cantilever chair was dependent on the region of the vehicle. PMID:22036450

  14. The dynamics of double slab subduction

    NASA Astrophysics Data System (ADS)

    Holt, A. F.; Royden, L. H.; Becker, T. W.

    2017-04-01

    We use numerical models to investigate the dynamics of two interacting slabs with parallel trenches. Cases considered are: a single slab reference, outward dipping slabs (out-dip), inward dipping slabs (in-dip) and slabs dipping in the same direction (same-dip). Where trenches converge over time (same-dip and out-dip systems), large positive dynamic pressures in the asthenosphere are generated beneath the middle plate and large trench-normal extensional forces are transmitted through the middle plate. This results in slabs that dip away from the middle plate at depth, independent of trench geometry. The single slab, the front slab in the same-dip case and both out-dip slabs undergo trench retreat and exhibit stable subduction. However, slabs within the other double subduction systems tend to completely overturn at the base of the upper mantle, and exhibit either trench advance (rear slab in same-dip), or near-stationary trenches (in-dip). For all slabs, the net slab-normal dynamic pressure at 330 km depth is nearly equal to the slab-normal force induced by slab buoyancy. For double subduction, the net outward force on the slabs due to dynamic pressure from the asthenosphere is effectively counterbalanced by the net extensional force transmitted through the middle plate. Thus, dynamic pressure at depth, interplate coupling and lithospheric stresses are closely linked and their effects cannot be isolated. Our results provide insights into both the temporal evolution of double slab systems on Earth and, more generally, how the various components of subduction systems, from mantle flow/pressure to interplate coupling, are dynamically linked.

  15. Photocopy of drawing (this photograph is an 8" x 10" ...

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

    Photocopy of drawing (this photograph is an 8" x 10" copy of an 8" x 10" negative; 1969 original architectural drawing, for 1969 addition, located at Building No. 458, NAS Pensacola, Florida) ARCHITECTURAL FIRST FLOOR PLAN FOR ADDITION TO BUILDING NO. 604 FOR A CONSOLIDATED PLATING FACILITY, SHEET 4 OF 135. - U.S. Naval Air Station, Assembly & Repair Shop, East Avenue, Pensacola, Escambia County, FL

  16. Photocopy of drawing (this photograph is an 8" x 10" ...

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

    Photocopy of drawing (this photograph is an 8" x 10" copy of an 8" x 10" negative; 1969 original architectural drawing, for 1969 addition, located at Building No. 458, NAS Pensacola, Florida) ARCHITECTURAL SECOND FLOOR PLAN FOR ADDITION TO BUILDING NO. 604 FOR A CONSOLIDATED PLATING FACILITY, SHEET 5 OF 135. - U.S. Naval Air Station, Assembly & Repair Shop, East Avenue, Pensacola, Escambia County, FL

  17. MANUFACTURING PROCESS FUNCTIONS--I. AN ALTERNATIVE MODEL AND ITS COMPARISON WITH EXISTING FUNCTIONS (AND)II. SELECTION OF TRAINEES AND CONTROL OF THEIR PROGRESS.

    ERIC Educational Resources Information Center

    GLOVER, J.H.

    THE CHIEF OBJECTIVE OF THIS STUDY OF SPEED-SKILL ACQUISITION WAS TO FIND A MATHEMATICAL MODEL CAPABLE OF SIMPLE GRAPHIC INTERPRETATION FOR INDUSTRIAL TRAINING AND PRODUCTION SCHEDULING AT THE SHOP FLOOR LEVEL. STUDIES OF MIDDLE SKILL DEVELOPMENT IN MACHINE AND VEHICLE ASSEMBLY, AIRCRAFT PRODUCTION, SPOOLMAKING AND THE MACHINING OF PARTS CONFIRMED…

  18. Support of Gulf of Mexico Hydrate Research Consortium: Activities to Support Establishment of a Sea Floor Monitoring Station Project

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carol Lutken

    The Gulf of Mexico Hydrates Research Consortium (GOM-HRC) was established in 1999 to assemble leaders in gas hydrates research. The Consortium is administered by the Center for Marine Resources and Environmental Technology, CMRET, at the University of Mississippi. The primary objective of the group is to design and emplace a remote monitoring station or sea floor observatory (MS/SFO) on the sea floor in the northern Gulf of Mexico by the year 2007, in an area where gas hydrates are known to be present at, or just below, the sea floor. This mission, although unavoidably delayed by hurricanes and other disturbances,more » necessitates assembling a station that will monitor physical and chemical parameters of the marine environment, including sea water and sea-floor sediments, on a more-or-less continuous basis over an extended period of time. In 2005, biological monitoring, as a means of assessing environmental health, was added to the mission of the MS/SFO. Establishment of the Consortium has succeeded in fulfilling the critical need to coordinate activities, avoid redundancies and communicate effectively among researchers in the arena of gas hydrates research. Complementary expertise, both scientific and technical, has been assembled to promote innovative research methods and construct necessary instrumentation. The observatory has now achieved a microbial dimension in addition to the geophysical, geological, and geochemical components it had already included. Initial components of the observatory, a probe that collects pore-fluid samples and another that records sea floor temperatures, were deployed in Mississippi Canyon 118 in May of 2005. Follow-up deployments, planned for fall 2005, had to be postponed due to the catastrophic effects of Hurricane Katrina (and later, Rita) on the Gulf Coast. Station/observatory completion, anticipated for 2007, will likely be delayed by at least one year. The CMRET has conducted several research cruises during this reporting period: one in April, one in June, one in September. April's effort was dedicated to surveying the mound at MC118 with the Surface-Source-Deep-Receiver (SSDR) seismic surveying system. This survey was completed in June and water column and bottom samples were collected via box coring. A microbial filtering system developed by Consortium participants at the University of Georgia was also deployed, run for {approx}12 hours and retrieved. The September cruise, designed to deploy, test, and in some cases recover, geochemical and microbial instruments and experiments took place aboard Harbor Branch's Seward Johnson and employed the Johnson SeaLink manned submersible. The seafloor monitoring station/observatory is funded approximately equally by three federal Agencies: Minerals Management Services (MMS) of the Department of the Interior (DOI), National Energy Technology Laboratory (NETL) of the Department of Energy (DOE), and the National Institute for Undersea Science and Technology (NIUST), an agency of the National Oceanographic and Atmospheric Administration (NOAA). Subcontractors with FY03 funding fulfilled their technical reporting requirements in a previously submitted report (41628R10). Only unresolved matching funds issues remain and will be addressed in the report of the University of Mississippi's Office of Research and Sponsored Programs. In addition, Barrodale Computing Services Ltd. (BCS) completed their work; their final report is the bulk of the semiannual report that precedes (abstract truncated)« less

  19. Low-cost Radon Reduction Pilot Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rose, William B.; Francisco, Paul W.; Merrin, Zachary

    The U.S. Department of Energy's Building America research team Partnership for Advanced Residential Retrofits conducted a primary scoping study on the impact of air sealing between the foundation and the living space on radon transport reduction across the foundation and living space floor assembly. Fifteen homes in the Champaign, Illinois, area participated in the study. These homes were instrumented for hourly continuous radon measurements and simultaneous temperature and humidity measurements. Blower door and zone pressure diagnostics were conducted at each house. The treatments consisted of using air-sealing foams at the underside of the floor that separated the living space frommore » the foundation and providing duct sealing on the ductwork that is situated in the foundation area. The hypothesis was that air sealing the floor system that separated the foundation from the living space should better isolate the living space from the foundation; this isolation should lead to less radon entering the living space from the foundation. If the hypothesis had been proven, retrofit energy-efficiency programs may have chosen to adopt these isolation methods for enhanced radon protection to the living space.« less

  20. Ecological Succession and Viability of Human-Associated Microbiota on Restroom Surfaces

    PubMed Central

    Gibbons, Sean M.; Schwartz, Tara; Fouquier, Jennifer; Mitchell, Michelle; Sangwan, Naseer; Kelley, Scott T.

    2014-01-01

    Human-associated bacteria dominate the built environment (BE). Following decontamination of floors, toilet seats, and soap dispensers in four public restrooms, in situ bacterial communities were characterized hourly, daily, and weekly to determine their successional ecology. The viability of cultivable bacteria, following the removal of dispersal agents (humans), was also assessed hourly. A late-successional community developed within 5 to 8 h on restroom floors and showed remarkable stability over weeks to months. Despite late-successional dominance by skin- and outdoor-associated bacteria, the most ubiquitous organisms were predominantly gut-associated taxa, which persisted following exclusion of humans. Staphylococcus represented the majority of the cultivable community, even after several hours of human exclusion. Methicillin-resistant Staphylococcus aureus (MRSA)-associated virulence genes were found on floors but were not present in assembled Staphylococcus pan-genomes. Viral abundances, which were predominantly enterophages, human papilloma virus, and herpesviruses, were significantly correlated with bacterial abundances and showed an unexpectedly low virus-to-bacterium ratio in surface-associated samples, suggesting that bacterial hosts are mostly dormant on BE surfaces. PMID:25398865

  1. Ecological succession and viability of human-associated microbiota on restroom surfaces

    DOE PAGES

    Gibbons, Sean M.; Schwartz, Tara; Fouquier, Jennifer; ...

    2014-11-14

    Human-associated bacteria dominate the built environment (BE). Following decontamination of floors, toilet seats, and soap dispensers in four public restrooms, in situ bacterial communities were characterized hourly, daily, and weekly to determine their successional ecology. The viability of cultivable bacteria, following the removal of dispersal agents (humans), was also assessed hourly. A late-successional community developed within 5 to 8 h on restroom floors and showed remarkable stability over weeks to months. Despite late-successional dominance by skin- and outdoor-associated bacteria, the most ubiquitous organisms were predominantly gut-associated taxa, which persisted following exclusion of humans. Staphylococcus represented the majority of the cultivablemore » community, even after several hours of human exclusion. Methicillin-resistant Staphylococcus aureus (MRSA)-associated virulence genes were found on floors but were not present in assembled Staphylococcus pan-genomes. Viral abundances, which were predominantly enterophages, human papilloma virus, and herpesviruses, were significantly correlated with bacterial abundances and showed an unexpectedly low virus-to-bacterium ratio in surface-associated samples, suggesting that bacterial hosts are mostly dormant on BE surfaces.« less

  2. Ecological succession and viability of human-associated microbiota on restroom surfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gibbons, Sean M.; Schwartz, Tara; Fouquier, Jennifer

    Human-associated bacteria dominate the built environment (BE). Following decontamination of floors, toilet seats, and soap dispensers in four public restrooms, in situ bacterial communities were characterized hourly, daily, and weekly to determine their successional ecology. The viability of cultivable bacteria, following the removal of dispersal agents (humans), was also assessed hourly. A late-successional community developed within 5 to 8 h on restroom floors and showed remarkable stability over weeks to months. Despite late-successional dominance by skin- and outdoor-associated bacteria, the most ubiquitous organisms were predominantly gut-associated taxa, which persisted following exclusion of humans. Staphylococcus represented the majority of the cultivablemore » community, even after several hours of human exclusion. Methicillin-resistant Staphylococcus aureus (MRSA)-associated virulence genes were found on floors but were not present in assembled Staphylococcus pan-genomes. Viral abundances, which were predominantly enterophages, human papilloma virus, and herpesviruses, were significantly correlated with bacterial abundances and showed an unexpectedly low virus-to-bacterium ratio in surface-associated samples, suggesting that bacterial hosts are mostly dormant on BE surfaces.« less

  3. Behaviour of reinforced concrete slabs with steel fibers

    NASA Astrophysics Data System (ADS)

    Baarimah, A. O.; Syed Mohsin, S. M.

    2017-11-01

    This paper investigates the potential effect of steel fiber added into reinforced concrete slabs. Four-point bending test is conducted on six slabs to investigate the structural behaviour of the slabs by considering two different parameters; (i) thickness of slab (ii) volume fraction of steel fiber. The experimental work consists of six slabs, in which three slabs are designed in accordance to Eurocode 2 to fulfil shear capacity characteristic, whereas, the other three slabs are designed with 17% less thickness, intended to fail in shear. Both series of slabs are added with steel fiber with a volume fraction of Vf = 0%, Vf = 1% and Vf = 2% in order to study the effect and potential of fiber to compensate the loss in shear capacity. The slab with Vf = 0% steel fiber and no reduction in thickness is taken as the control slab. The experimental result suggests promising improvement of the load carrying capacity (up to 32%) and ductility (up to 87%) as well as delayed in crack propagation for the slabs with Vf = 2%. In addition, it is observed that addition of fibers compensates the reduction in the slab thickness as well as changes the failure mode of the slab from brittle to a more ductile manner.

  4. Slab-pull and slab-push earthquakes in the Mexican, Chilean and Peruvian subduction zones

    NASA Astrophysics Data System (ADS)

    Lemoine, A.; Madariaga, R.; Campos, J.

    2002-09-01

    We studied intermediate depth earthquakes in the Chile, Peru and Mexican subduction zones, paying special attention to slab-push (down-dip compression) and slab-pull (down-dip extension) mechanisms. Although, slab-push events are relatively rare in comparison with slab-pull earthquakes, quite a few have occurred recently. In Peru, a couple slab-push events occurred in 1991 and one slab-pull together with several slab-push events occurred in 1970 near Chimbote. In Mexico, several slab-push and slab-pull events occurred near Zihuatanejo below the fault zone of the 1985 Michoacan event. In central Chile, a large M=7.1 slab-push event occurred in October 1997 that followed a series of four shallow Mw>6 thrust earthquakes on the plate interface. We used teleseismic body waveform inversion of a number of Mw>5.9 slab-push and slab-pull earthquakes in order to obtain accurate mechanisms, depths and source time functions. We used a master event method in order to get relative locations. We discussed the occurrence of the relatively rare slab-push events in the three subduction zones. Were they due to the geometry of the subduction that produces flexure inside the downgoing slab, or were they produced by stress transfer during the earthquake cycle? Stress transfer can not explain the occurence of several compressional and extensional intraplate intermediate depth earthquakes in central Chile, central Mexico and central Peru. It seemed that the heterogeneity of the stress field produced by complex slab geometry has an important influence on intraplate intermediate depth earthquakes.

  5. Imaging the Peruvian flat slab with Rayliegh wave tomography

    NASA Astrophysics Data System (ADS)

    Knezevic Antonijevic, Sanja

    In subduction zones the oceanic plates descend at a broad range of dip angles. A "flat slab" is an oceanic plate that starts to subduct steeply, but bends at 100 km depth and continues almost horizontally for several hundred kilometers. This unusual slab geometry has been linked to various geologic features, including the cessation of arc volcanism, basement core uplifts removed far from subducting margins, and the formation of high plateaus. Despite the prevalence of flat slabs worldwide since the Proterozoic, questions on how flat slabs form, persist, and re-steepen remains a topic of ongoing research. Even less clear is how this phenomenon relates to unusual features observed at the surface. To better understand the causes and consequences of slab flattening I focus on the Peruvian flat slab. This is not only the biggest flat slab region today, but due to the oblique angle at which the Nazca Plate subducts under the South American Plate, it also provides unique opportunity to get insights into the temporal evolution of the flat slab. Using ambient noise and earthquake-generated Rayleigh waves recorded at several contemporary dense seismic networks, I was able to perform unprecedentedly high resolution imaging of the subduction zone in southern Peru. Surprisingly, instead of imaging a vast flat slab region as expected, I found that the flat slab tears and re-steepens north of the subducting Nazca Ridge. The change in slab geometry is associated with variations in the slab's internal strain along strike, as inferred from slab-related anisotropy. Based on newly-discovered features I discuss the critical role of the subducting ridges in the formation and longevity of flat slabs. The slab tear created a new mantle pathway between the torn slab and the flat slab remnant to the east, and is possibly linked to the profound low velocity anomaly located under the eastern corner of the flat slab. Finally, I re-evaluate the connection between slab flattening and volcanic patterns at the surface. These findings have important implications for all present-day and paleo-flat slab regions, such as the one proposed for the western United States during the Laramide orogeny 80-55 Ma.

  6. Effect of rheological approximations on slab detachment in 3D numerical simulations of continental collision

    NASA Astrophysics Data System (ADS)

    Pusok, Adina E.; Kaus, Boris; Popov, Anton

    2017-04-01

    It is commonly accepted that slab detachment results from the development of extensional stresses within the subducting slab. Subduction slowdown due to arrival of buoyant continental material at the trench is considered to cause such stress build up in the slab. Following slab detachment, slab pull partially or completely loses its strength and hot asthenosphere may flow through the slab window, which can have major consequences for continental collision. The dynamics of slab detachment has been extensively studied in 2D (i.e. analytical and numerical), but 3D models of slab detachment during continental collision remain largely unexplored. Some of the previous 3D models have investigated the role of an asymmetric margin on the propagation of slab detachment (van Hunen and Allen, 2011), the impact of slab detachment on the curvature of orogenic belts (Capitanio and Replumaz, 2013), the role of the collision rate on slab detachment depth (Li et al., 2013) or the effect of along-trench variations on slab detachment (Duretz et al., 2014). However, rheology of mantle and lithosphere is known to have a major influence on the dynamics of subduction. Here, we explore a range of different rheological approximations to understand their sensitivity on the possible scenarios. We employ the code LaMEM (Kaus et al., 2016) to perform 3D simulations of subduction/continental collision in an integrated lithospheric and upper-mantle scale model. The models exhibit a wide range of behaviours depending on the rheological law employed: from linear, to temperature-dependent visco-elasto-plastic rheology that takes into account both diffusion and dislocation creep. For example, we find that slab dynamics varies drastically between end member models: in viscous approximations, slab detachment is slow, dominated by viscous thinning, while for a non-linear visco-elasto-plastic rheology, slab detachment is relatively fast, dominated by plastic breaking and inducing strong mantle flow in the slab window. Moreover, in models of viscous approximation, slab break-off starts in the slab interior due tot the nature of slab necking, while in models of non-linear visco-elasto-plastic rheology, slab tear will first occur at the edges of the continental collision.

  7. van der Waals torque

    NASA Astrophysics Data System (ADS)

    Esquivel-Sirvent, Raul; Schatz, George

    2014-03-01

    The theory of generalized van der Waals forces by Lifshtz when applied to optically anisotropic media predicts the existence of a torque. In this work we present a theoretical calculation of the van der Waals torque for two systems. First we consider two isotropic parallel plates where the anisotropy is induced using an external magnetic field. The anisotropy will in turn induce a torque. As a case study we consider III-IV semiconductors such as InSb that can support magneto plasmons. The calculations of the torque are done in the Voigt configuration, that occurs when the magnetic field is parallel to the surface of the slabs. The change in the dielectric function as the magnetic field increases has the effect of decreasing the van der Waals force and increasing the torque. Thus, the external magnetic field is used to tune both the force and torque. The second example we present is the use of the torque in the non retarded regime to align arrays of nano particle slabs. The torque is calculated within Barash and Ginzburg formalism in the nonretarded limit, and is quantified by the introduction of a Hamaker torque constant. Calculations are conducted between anisotropic slabs of materials including BaTiO3 and arrays of Ag nano particles. Depending on the shape and arrangement of the Ag nano particles the effective dielectric function of the array can be tuned as to make it more or less anisotropic. We show how this torque can be used in self assembly of arrays of nano particles. ref. R. Esquivel-Sirvent, G. C. Schatz, Phys. Chem C, 117, 5492 (2013). partial support from DGAPA-UNAM.

  8. Slab interactions in 3-D subduction settings: The Philippine Sea Plate region

    NASA Astrophysics Data System (ADS)

    Holt, Adam F.; Royden, Leigh H.; Becker, Thorsten W.; Faccenna, Claudio

    2018-05-01

    The importance of slab-slab interactions is manifested in the kinematics and geometry of the Philippine Sea Plate and western Pacific subduction zones, and such interactions offer a dynamic basis for the first-order observations in this complex subduction setting. The westward subduction of the Pacific Sea Plate changes, along-strike, from single slab subduction beneath Japan, to a double-subduction setting where Pacific subduction beneath the Philippine Sea Plate occurs in tandem with westward subduction of the Philippine Sea Plate beneath Eurasia. Our 3-D numerical models show that there are fundamental differences between single slab systems and double slab systems where both subduction systems have the same vergence. We find that the observed kinematics and slab geometry of the Pacific-Philippine subduction can be understood by considering an along-strike transition from single to double subduction, and is largely independent from the detailed geometry of the Philippine Sea Plate. Important first order features include the relatively shallow slab dip, retreating/stationary trenches, and rapid subduction for single slab systems (Pacific Plate subducting under Japan), and front slabs within a double slab system (Philippine Sea Plate subducting at Ryukyu). In contrast, steep to overturned slab dips, advancing trench motion, and slower subduction occurs for rear slabs in a double slab setting (Pacific subducting at the Izu-Bonin-Mariana). This happens because of a relative build-up of pressure in the asthenosphere beneath the Philippine Sea Plate, where the asthenosphere is constrained between the converging Ryukyu and Izu-Bonin-Mariana slabs. When weak back-arc regions are included, slab-slab convergence rates slow and the middle (Philippine) plate extends, which leads to reduced pressure build up and reduced slab-slab coupling. Models without back-arcs, or with back-arc viscosities that are reduced by a factor of five, produce kinematics compatible with present-day observations.

  9. Improved Nazca slab structure from teleseismic P-wave tomography along the Andean margin

    NASA Astrophysics Data System (ADS)

    Portner, D. E.; Beck, S. L.; Scire, A. C.; Zandt, G.

    2017-12-01

    South America marks the longest continuous ocean-continent subduction zone. As such, there is significant along-strike variability in the subducting Nazca slab structure and the tectonics of the South American margin. Most notably two gaps in the otherwise continuous volcanic arc are correlated with regions of flat slab subduction, indicating that the structure of the Nazca slab plays a controlling role in South American tectonics. Traditionally in subduction zones, our knowledge of slab structure is defined by Wadati-Benioff zone earthquakes. While this method allows for the determination of large-scale variations in Nazca slab structure such as regions of flat slab subduction, a scarcity of intermediate-depth earthquakes hinders our ability to observe the smaller-scale structural variations in the slab that may be critical to our understanding of the geologic record. We use an updated, larger dataset for finite-frequency teleseismic P-wave tomography including relative arrival times from >700 seismic stations along the Andean margin to image the detailed Nazca slab structure throughout the upper mantle and uppermost lower mantle between latitudes 5°S and 45°S. Our results show prominent variations in slab character along the margin. Slab dip varies significantly, from sub-vertical inboard of the Peruvian flat slab segment to 30° dip south of the Pampean flat slab, while the slab's velocity anomaly amplitude changes dramatically near the Pampean flat slab region. High slab velocities north of the Pampean region relative to the south indicate variable slab thermal structures that correspond roughly with the locations of deep (>500 km depth) earthquakes that also occur exclusively north of the Pampean region. Additionally, a wider regional footprint increases our sampling of the upper-lower mantle boundary, improving constraints on the slab's interaction with the 660 km discontinuity along strike. We see that the Nazca slab appears to penetrate into the lower mantle along the majority of the margin.

  10. Creative Building Design for Innovative Earth Science Teaching and Outreach (Invited)

    NASA Astrophysics Data System (ADS)

    Chan, M. A.

    2009-12-01

    Earth Science departments can blend the physical “bricks and mortar” facility with programs and educational displays to create a facility that is a permanent outreach tool and a welcoming home for teaching and research. The new Frederick Albert Sutton building at the University of Utah is one of the first LEED (Leadership in Energy and Environmental Design) certified Earth Science buildings in the country. Throughout the structure, creative architectural designs are combined with sustainability, artful geologic displays, and community partnerships. Distinctive features of the building include: 1) Unique, inviting geologic designs such as cross bedding pattern in the concrete foundation; “a river runs through it” (a pebble tile “stream” inside the entrance); “confluence” lobby with spectacular Eocene Green River fossil fish and plant walls; polished rock slabs; and many natural stone elements. All displays are also designed as teaching tools. 2) Student-generated, energy efficient, sustainable projects such as: solar tube lights, xeriscape & rock monoliths, rainwater collection, roof garden, pervious cement, and energy monitoring. 3) Reinforced concrete foundation for vibration-free analytical measurements, and exposed lab ceilings for duct work and infrastructure adaptability. The spectacular displays for this special project were made possible by new partnerships within the community. Companies participated with generous, in-kind donations (e.g., services, stone flooring and slabs, and landscape rocks). They received recognition in the building and in literature acknowledging donors. A beautiful built environment creates space that students, faculty, and staff are proud of. People feel good about coming to work, and they are happy about their surroundings. This makes a strong recruiting tool, with more productive and satisfied employees. Buildings with architectural interest and displays can showcase geology as art and science, while highlighting what Earth Scientists do. This approach can transform our Earth Science buildings into destinations for visitors, to show evoke inquiry. The building becomes a centerpiece, not another blank box on campus. Administrators at the University of Utah now want other new building structures to emulate our geoscience example. Done right, “bricks and mortar” can build stronger departments, infuse Earth Science into the community, and enhance our educational missions. LEED-certified Earth Science building with Eocene fossil fish wall, river pebble pattern in floor tile, displays, and student gathering areas.

  11. KSC-2009-2797

    NASA Image and Video Library

    2009-04-20

    CAPE CANAVERAL, Fla. –– In High Bay 4 of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, the yellow framework at top, nicknamed the "birdcage," is lifted high above the floor for a fit check with the Crew Module, or CM, and Launch Abort System, or LAS, assembly at lower left for the Ares I-X rocket. Ares I-X is the flight test for the Ares I. The I-X flight will provide NASA an early opportunity to test and prove hardware, facilities and ground operations associated with Ares I. The launch of the 327-foot-tall, full-scale Ares I-X is targeted for July 2009. Photo credit: NASA/Jack Pfaller

  12. Microsecond MD Simulations of Nano-patterned Polymer Brushes on Self-Assembled Monolayers

    NASA Astrophysics Data System (ADS)

    Buie, Creighton; Qiu, Liming; Cheng, Kwan; Park, Soyeun

    2010-03-01

    Nano-patterned polymer brushes end-grafted onto self-assembled monolayers have gained increasing research interests due to their unique thermodynamic properties and their chemical and biomedical applications in colloids, biosensing and tissue engineering. So far, the interactions between the polymer brushes with the surrounding environments such as the floor and solvent at the nanometer length scale and microsecond time scale are still difficult to obtained experimentally and computationally. Using a Coarse-Grained MD approach, polymer brushes of different monomeric lengths, grafting density and hydrophobicity of the monomers grafted on self-assembled monolayers and in explicit solvent were studied. Molecular level information, such as lateral diffusion, transverse height and volume contour of the brushes, were calculated from our microsecond-MD simulations. Our results demonstrated the significance of the hydration of the polymer in controlling the conformational arrangement of the polymer brushes.

  13. Casimir forces on a bi-anisotropic absorbing magneto-dielectric slab between two parallel conducting plates

    NASA Astrophysics Data System (ADS)

    Amooshahi, Majid; Shoughi, Ali

    2018-05-01

    A fully canonical quantization of electromagnetic field in the presence of a bi-anisotropic absorbing magneto-dielectric slab is demonstrated. The electric and the magnetic polarization densities of the magneto-dielectric slab are defined in terms of the dynamical variables modeling the slab and the coupling tensors that couple the electromagnetic field to the slab. The four susceptibility tensors of the bi-anisotropic magneto-dielectric slab are expressed in terms of the coupling tensors that couple an electromagnetic field to the slab. It is shown that the four susceptibility tensors of the bi-anisotropic magneto-dielectric slab satisfy Kramers-Kronig relations. The Maxwell’s equations are exactly solved in the presence of the bi-anisotropic magneto-dielectric slab. The tangential and the normal components of the Casimir forces exerted on the bi-anisotropic magnet-dielectric slab exactly are calculated in the vacuum state and thermal state of the total system. It is shown that the tangential components of the Casimir forces vanish when the bi-anisotropic slab is converted to an isotropic slab.

  14. Ejectable underwater sound source recovery assembly

    NASA Technical Reports Server (NTRS)

    Irick, S. C. (Inventor)

    1974-01-01

    An underwater sound source is described that may be ejectably mounted on any mobile device that travels over water, to facilitate in the location and recovery of the device when submerged. A length of flexible line maintains a connection between the mobile device and the sound source. During recovery, the sound source is located be particularly useful in the recovery of spent rocket motors that bury in the ocean floor upon impact.

  15. View of debris assembled at the Kennedy Space Center from STS 51-L

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Large portion of the three main engines of the Space Shuttle Orbiter Challenger have been recovered from the floor of the Atlantic Ocean to the east of the Kennedy Space Center. They have been moved to a large storage building to the east of the Logistics Facility at Complex 39. Most of the pieces were recovered by the Coast Guard and Navy following the accident.

  16. Rapid Assembly Module for Traypacks

    DTIC Science & Technology

    2006-01-01

    napkins , trays, utensils, garbage bags, etc. Food items will be dry, canned, or other retorted goods that are shelf-stable and require no...marked on the floor of the container with ink . When an alternative configuration is selected, a new manual will be issued by the PI. The revised manual...50 solders one meal. Accessories will include such items as cups, napkins , trays, utensils, garbage bags, etc. Food items will be dry, canned, or

  17. Tomography of the subducting Pacific slab and the 2015 Bonin deepest earthquake (Mw 7.9).

    PubMed

    Zhao, Dapeng; Fujisawa, Moeto; Toyokuni, Genti

    2017-03-15

    On 30 May 2015 an isolated deep earthquake (~670 km, Mw 7.9) occurred to the west of the Bonin Islands. To clarify its causal mechanism and its relationship to the subducting Pacific slab, we determined a detailed P-wave tomography of the deep earthquake source zone using a large number of arrival-time data. Our results show that this large deep event occurred within the subducting Pacific slab which is penetrating into the lower mantle. In the Izu-Bonin region, the Pacific slab is split at ~28° north latitude, i.e., slightly north of the 2015 deep event hypocenter. In the north the slab becomes stagnant in the mantle transition zone, whereas in the south the slab is directly penetrating into the lower mantle. This deep earthquake was caused by joint effects of several factors, including the Pacific slab's fast deep subduction, slab tearing, slab thermal variation, stress changes and phase transformations in the slab, and complex interactions between the slab and the ambient mantle.

  18. 3D Visualization of Sheath Folds in Roman Marble from Ephesus, Turkey

    NASA Astrophysics Data System (ADS)

    Wex, Sebastian; Passchier, Cornelis W.; de Kemp, Eric A.; Ilhan, Sinan

    2013-04-01

    Excavation of a palatial 2nd century AD house (Terrace House Two) in the ancient city of Ephesus, Turkey in the 1970s produced 10.313 pieces of colored, folded marble which belonged to 54 marble plates of 1.6 cm thickness that originally covered the walls of the banquet hall of the house. The marble plates were completely reassembled and restored by a team of workers over the last 6 years. The plates were recognized as having been sawn from two separate large blocks of "Cipollino verde", a green mylonitized marble from Karystos on the Island of Euboea, Greece. After restoration, it became clear that all slabs had been placed on the wall in approximately the sequence in which they had been cut off by a Roman stone saw. As a result, the marble plates give a full 3D insight in the folded internal structure of 1m3 block of mylonite. The restoration of the slabs was recognized as a first, unique opportunity for detailed reconstruction of the 3D geometry of m-scale folds in mylonitized marble. Photographs were taken of each slab and used to reconstruct their exact arrangement within the originally quarried blocks. Outlines of layers were digitized and a full 3D reconstruction of the internal structure of the block was created using ArcMap and GOCAD. Fold structures in the block include curtain folds and multilayered sheath folds. Several different layers showing these structures were digitized on the photographs of the slab surfaces and virtually mounted back together within the model of the marble block. Due to the serial sectioning into slabs, with cm-scale spacing, the visualization of the 3D geometry of sheath folds was accomplished with a resolution better than 4 cm. Final assembled 3D images reveal how sheath folds emerge from continuous layers and show their overall consistency as well as a constant hinge line orientation of the fold structures. Observations suggest that a single deformation phase was responsible for the evolution of "Cipollino verde" structures. Furthermore the XY plane of all analyzed sheath folds was orientated perpendicular to the layering of the marble, indicating a compressional component during shear deformation. This study sheds light on the general evolution and possible interpretation of sheath folds, currently still subject of debate, and on the structural evolution of "Cipollino verde", which is still used in modern architectural design. Furthermore, the detailed analysis of the slabs helps in the interpretation and reconstruction of Roman stone saws. For future applications this work could serve as an excellent 3D test set for geologic reconstruction methodologies and interpolation algorithms. The results presented could only be obtained by close cooperation of workers in geology and archaeology.

  19. Tomographic imaging of the effects of Peruvian flat slab subduction on the Nazca slab and surrounding mantle under central and southern Peru

    NASA Astrophysics Data System (ADS)

    Scire, A. C.; Zandt, G.; Beck, S. L.; Bishop, B.; Biryol, C. B.; Wagner, L. S.; Long, M. D.; Minaya, E.; Tavera, H.

    2014-12-01

    The modern central Peruvian Andes are dominated by a laterally extensive region of flat slab subduction. The Peruvian flat slab extends for ~1500 km along the strike of the Andes, correlating with the subduction of the Nazca Ridge in the south and the theorized Inca Plateau in the north. We have used data from the CAUGHT and PULSE experiments for finite frequency teleseismic P- and S-wave tomography to image the Nazca slab in the upper mantle below 95 km depth under central Peru between 10°S and 18°S as well as the surrounding mantle. Since the slab inboard of the subducting Nazca Ridge is mostly aseismic, our results provide important constraints on the geometry of the subducting Nazca slab in this region. Our images of the Nazca slab suggest that steepening of the slab inboard of the subducting Nazca Ridge locally occurs ~100 km further inland than was indicated in previous studies. The region where we have imaged the steepening of the Nazca slab inboard of the Nazca Ridge correlates with the location of the Fitzcarrald Arch, a long wavelength upper plate topographic feature which has been suggested to be a consequence of ridge subduction. When the slab steepens inboard of the flat slab region, it does so at a very steep (~70°) angle. The transition from the Peruvian flat slab to the more normally dipping slab south of 16°S below Bolivia is characterized by an abrupt bending of the slab anomaly in the mantle in response to the shift from flat to normal subduction. The slab anomaly appears to be intact south of the Nazca Ridge with no evidence for tearing of the slab in response to the abrupt change in slab dip. A potential tear in the slab is inferred from an observed offset in the slab anomaly north of the Nazca Ridge extending subparallel to the ridge axis between 130 and 300 km depth. A high amplitude (-5-6%) slow S-wave velocity anomaly is observed below the projection of the Nazca Ridge. This anomaly appears to be laterally confined to the mantle directly below projection of the Nazca Ridge but descends to ~300 km depth in the mantle. This sub-slab slow anomaly may correlate with vertical mantle flow induced by movement of material through the inferred tear in the slab north of the Nazca Ridge or alternately may represent a long-lived feature of the sub-slab mantle possibly associated with the development of the Nazca Ridge at the Easter Island hot spot.

  20. How mantle slabs drive plate tectonics.

    PubMed

    Conrad, Clinton P; Lithgow-Bertelloni, Carolina

    2002-10-04

    The gravitational pull of subducted slabs is thought to drive the motions of Earth's tectonic plates, but the coupling between slabs and plates is not well established. If a slab is mechanically attached to a subducting plate, it can exert a direct pull on the plate. Alternatively, a detached slab may drive a plate by exciting flow in the mantle that exerts a shear traction on the base of the plate. From the geologic history of subduction, we estimated the relative importance of "pull" versus "suction" for the present-day plates. Observed plate motions are best predicted if slabs in the upper mantle are attached to plates and generate slab pull forces that account for about half of the total driving force on plates. Slabs in the lower mantle are supported by viscous mantle forces and drive plates through slab suction.

  1. Plate tectonic reconstruction of the northeast Eurasian margin and Alaska since 50 Ma using subducted slab constraints

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Chen, Y. W.

    2016-12-01

    Seismic tomographic studies have revealed a swath of flat slab anomalies in the mantle transition zone at 410 to 660 km depths under Japan, Korea and NE China that continue northwards at deeper depths under the Russian Far East. These slab anomalies are remarkable because they appear to be continuous from their western edge far inland (>2000 km) under the NE Eurasian margin to the present-day NW Pacific subduction zones, which suggests they are Pacific slabs that were subducted in the Cenozoic. Other studies have proposed that some of these slabs were subducted at an ancient subduction zone during the Mesozoic or earlier. Here we discuss the fate of these slabs and their implications for the plate tectonic reconstruction of the NW Pacific margin along NE Asia and Alaska. We present both new and recently published slab mapping (Wu et al., 2016; JGR Solid Earth) including 30 major and minor slabs mapped in 3D from MITP08 global seismic tomography. We unfolded our mapped slabs to a spherical Earth model to estimate their pre-subduction size, shape and locations. The slab constraints were input into GPlates software to constrain a new regional NW Pacific plate tectonic reconstruction in the Cenozoic. Mapped slabs included the Marianas, Izu-Bonin, Japan and Kuril slabs, the Philippine Sea slabs and Aleutian slabs under the Bering Sea. Our mapped western Pacific slabs between the southernmost Izu-Bonin trench and the western Aleutians had unfolded E-W lengths of 3400 to 4900 km. Our plate model shows that these slabs are best reconstructed as Pacific slabs that were subducted in the Cenozoic and account for fast Pacific subduction along the NE Eurasian margin since plate reorganization at 50 Ma. Our mapped northern Kuril slab edge near the western Aleutians and a southern edge at the southernmost Izu-Bonin trench are roughly east-west and consistent with the orientations of Pacific absolute motions since 50 Ma. We interpret these long E-W slab edges as STEP fault-type transforms (i.e. lithospheric tears that progressively formed during subduction). We further discuss our plate model against the opening of the NW Pacific marginal basins in the Cenozoic, including the Japan Sea, Kuril Basin and Okhotsk Sea.

  2. Stress regime in the Philippine Sea slab beneath Kanto, Japan

    NASA Astrophysics Data System (ADS)

    Nakajima, Junichi; Hasegawa, Akira; Hirose, Fuyuki

    2011-08-01

    We determine the focal mechanisms of earthquakes within the Philippine Sea slab beneath the Tokyo metropolitan area, and perform stress tensor inversions to investigate the detailed stress field within the slab. The results show a characteristic spatial variation in earthquake-generating stress. Slab stress in northeastern part of the PHS slab is characterized by down-dip tension (DDT), except for the uppermost tip of the seismic portion of the slab where down-dip compression (DDC) stress is dominant. We interpret that DDT is caused by the net slab pull and DDC is attributable to local resistance to subduction at the tip of the slab. In southwestern part of the PHS slab, σ1 and σ3 are generally rotated oblique to the dip of the slab, suggesting that earthquakes occur under stress conditions of neither DDC nor DDT. The rotations in σ1 and σ3 may be related to stress accumulation by the slip deficit along the asperity of the 1923 Kanto earthquake (M7.9).

  3. KSC-2009-1397

    NASA Image and Video Library

    2009-01-28

    CAPE CANAVERAL, Fla. – In the Vehicle Assembly Building's high bay 3 at NASA's Kennedy Space Center in Florida, framework is lifted to the 16th floor for modifications related to the Ares I-X. The refurbishment of the facility is for the Constellation Program's Ares vehicles. The Ares I and Ares V rockets will be 325 feet and 360 feet tall, respectively, considerably taller than the space shuttle atop its mobile launcher platform. Photo credit: NASA/Troy Cryder

  4. KSC-2009-1398

    NASA Image and Video Library

    2009-01-28

    CAPE CANAVERAL, Fla. –In the Vehicle Assembly Building's high bay 3 at NASA's Kennedy Space Center in Florida, framework is lifted to the 16th floor for modifications related to the Ares I-X. The refurbishment of the facility is for the Constellation Program's Ares vehicles. The Ares I and Ares V rockets will be 325 feet and 360 feet tall, respectively, considerably taller than the space shuttle atop its mobile launcher platform. Photo credit: NASA/Troy Cryder

  5. Pilot Fullerton sleeps on aft flight deck

    NASA Image and Video Library

    1982-03-30

    STS003-22-113 (24 March 1982) --- Astronaut Gordon Fullerton, STS-3 pilot, wearing communication kit assembly mini-headset (HDST), sleeps on aft flight deck resting his back against the floor and his feet against commander's ejection seat (S1) back. On-orbit station control panel A8 and payload station panel L15 appear above Fullerton. Special clips for holding notebooks open and beverage containers are velcroed on various panels. Photo credit: NASA

  6. Skylab

    NASA Image and Video Library

    1970-01-01

    This photograph was taken during assembly of the bottom and upper floors of the Skylab Orbital Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment.

  7. Commander Lousma adds water to a beverage container on middeck

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Commander Lousma, wearing communications kit assembly (assy) mini headset (HDST), fills beverage container using the JSC water dispenser kit water gun to prepare a juice drink. Lousma is wearing the trousers and shirt of a three-piece shuttle constant wear garment as he floats above the potable water tank on the middeck floor. The constant wear garment jacket is secured on a side hatch handle (background) to avoid zero gravity effect.

  8. Bridge approach slabs for Missouri DOT field evaluation of alternative and cost efficient bridge approach slabs.

    DOT National Transportation Integrated Search

    2013-05-01

    Based on a recent study on cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et : al. 2010) has recommended three new BAS designs for possible implementation by MoDOT namely a) 20 feet cast-inplace : slab with sleeper slab (C...

  9. (abstract) A Miniature, High-Sensitivity, Electron-Tunneling Accelerometer

    NASA Technical Reports Server (NTRS)

    Gabrielson, Thomas B.; Rockstad, Howard K.; Tang, Tony K.

    1994-01-01

    A prototype low-noise accelerometer has been fabricated with an electron-tunneling transducer. By measuring the tunneling current between an electrode on the proof mass and a feedback-controlled monitor electrode, very small accelerations can be detected with high responsivity. This particular prototype (10x10x1.5 mm) was designed for underwater acoustic measurement from a few hertz to 1 kHz. The measured responsivity below the fundamental device resonance at 100 Hz is roughly 1500 volts per m/s(sup 2) with a measured noise spectral density of 10(sup -6) m/s(sup 2) per root hertz or less between 30 and 300 Hz. The noise floor is controlled primarily by 1/f noise in the tunneling current although the noise floor reaches the theoretical molecular-agitation limit at 100 hertz. The responsivity and directivity of the device were measured in a standard gradient-hydrophone calibrator; the noise floor was determined in a vacuum-ionization chamber assembled from commercial off-the-shelf components; and the detailed dynamics of the proof-mass motion were examined using a heterodyne laser interferometer that was scanned across the surface and synchronously detected with respect to the excitation.

  10. Tomography of the subducting Pacific slab and the 2015 Bonin deepest earthquake (Mw 7.9)

    PubMed Central

    Zhao, Dapeng; Fujisawa, Moeto; Toyokuni, Genti

    2017-01-01

    On 30 May 2015 an isolated deep earthquake (~670 km, Mw 7.9) occurred to the west of the Bonin Islands. To clarify its causal mechanism and its relationship to the subducting Pacific slab, we determined a detailed P-wave tomography of the deep earthquake source zone using a large number of arrival-time data. Our results show that this large deep event occurred within the subducting Pacific slab which is penetrating into the lower mantle. In the Izu-Bonin region, the Pacific slab is split at ~28° north latitude, i.e., slightly north of the 2015 deep event hypocenter. In the north the slab becomes stagnant in the mantle transition zone, whereas in the south the slab is directly penetrating into the lower mantle. This deep earthquake was caused by joint effects of several factors, including the Pacific slab’s fast deep subduction, slab tearing, slab thermal variation, stress changes and phase transformations in the slab, and complex interactions between the slab and the ambient mantle. PMID:28295018

  11. Tomography of the subducting Pacific slab and the 2015 Bonin deepest earthquake (Mw 7.9)

    NASA Astrophysics Data System (ADS)

    Zhao, Dapeng; Fujisawa, Moeto; Toyokuni, Genti

    2017-03-01

    On 30 May 2015 an isolated deep earthquake (~670 km, Mw 7.9) occurred to the west of the Bonin Islands. To clarify its causal mechanism and its relationship to the subducting Pacific slab, we determined a detailed P-wave tomography of the deep earthquake source zone using a large number of arrival-time data. Our results show that this large deep event occurred within the subducting Pacific slab which is penetrating into the lower mantle. In the Izu-Bonin region, the Pacific slab is split at ~28° north latitude, i.e., slightly north of the 2015 deep event hypocenter. In the north the slab becomes stagnant in the mantle transition zone, whereas in the south the slab is directly penetrating into the lower mantle. This deep earthquake was caused by joint effects of several factors, including the Pacific slab’s fast deep subduction, slab tearing, slab thermal variation, stress changes and phase transformations in the slab, and complex interactions between the slab and the ambient mantle.

  12. A User’s Guide to the PLTEMP/ANL Code

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Olson, A. P.; Kalimullah, M.; Feldman, E. E.

    2016-07-25

    PLTEMP/ANL V4.2 is a program that obtains a steady-state flow and temperature solution for a nuclear reactor core, or for a single fuel assembly. It is based on an evolutionary sequence of codes originally used for plate temperatures, hence “PLTEMP”, developed at Argonne National Laboratory over several decades. Fueled and non-fueled regions are modeled. Each fuel assembly consists of one or more plates or tubes separated by coolant channels. The fuel plates may have one to five layers of different materials, each with heat generation. The width of a fuel plate may be divided into multiple longitudinal stripes, each withmore » its own axial power shape. The temperature solution is effectively 2-dimensional. It begins with a one-dimensional solution across all coolant channels and fuel plates or tubes within a given fuel assembly, at the entrance to the assembly. The temperature solution is repeated for each axial node along the length of the fuel assembly. The geometry may be either slab or radial, corresponding to fuel assemblies made of a series of flat (or slightly curved) plates, or of nested tubes. A variety of thermal-hydraulic correlations are available with which to determine safety margins such as onset-of-nucleate boiling ratio(ONBR), departure from nucleate boiling ratio (DNBR), and onset of flow instability ratio (OFIR). Coolant properties for either light or heavy water are obtained from FORTRAN functions rather than from tables. The code is intended for thermal-hydraulic analysis of research reactor performance in the sub-cooled boiling regime. Both turbulent and laminar flow regimes can be modeled. Options to calculate both forced flow and natural circulation are available. A general search capability is available (Appendix XII) to greatly reduce the reactor analyst’s time.« less

  13. Experimental sensitivity analysis of subsoil-slab behaviour regarding degree of fibre-concrete slab reinforcement

    NASA Astrophysics Data System (ADS)

    Hrubesova, E.; Lahuta, H.; Mohyla, M.; Quang, T. B.; Phi, N. D.

    2018-04-01

    The paper is focused on the sensitivity analysis of behaviour of the subsoil – foundation system as regards the variant properties of fibre-concrete slab resulting into different relative stiffness of the whole cooperating system. The character of slab and its properties are very important for the character of external load transfer, but the character of subsoil cannot be neglected either because it determines the stress-strain behaviour of the all system and consequently the bearing capacity of structure. The sensitivity analysis was carried out based on experimental results, which include both the stress values in soil below the foundation structure and settlements of structure, characterized by different quantity of fibres in it. Flat dynamometers GEOKON were used for the stress measurements below the observed slab, the strains inside slab were registered by tensometers, the settlements were monitored geodetically. The paper is focused on the comparison of soil stresses below the slab for different quantity of fibres in structure. The results obtained from the experimental stand can contribute to more objective knowledge of soil – slab interaction, to the evaluation of real carrying capacity of the slab, to the calibration of corresponding numerical models, to the optimization of quantity of fibres in the slab, and finally, to higher safety and more economical design of slab.

  14. Tomographic Signatures of Ridge Subduction Along Western North America: Implications for Northern Cordillera Plate Tectonics Since the Cretaceous

    NASA Astrophysics Data System (ADS)

    Lin, Y. A.; Wu, J.

    2017-12-01

    A number of northern Cordillera plate reconstructions have predicted subduction of the Kula-Farallon ridge and possibly other ridges along western North America after the late Mesozoic. The timing and location of these predicted ridge subduction events have been controversial, with implications for rapid northward terrane motions (i.e. the Baja-British Columbia hypothesis). In contrast, Sigloch and Mihalynuk (2013) proposed an archipelago-style plate model that placed one or several Jurassic-Cretaceous ocean basins between the Farallon plate and western North America, which apparently would preclude any sustained Kula-Farallon ridge subduction along western North America. In this study we test the viability of these models by mapping and unfolding subducted slabs from MITP08 tomography (Li et al., 2008) between Alaska and California within the upper 1500 km mantle. Our aim was to locate significant slab gaps that might be related to ancient ridge subduction `slab windows'. Tomographic velocities were extracted and displayed on our mapped slabs following the methods of Wu et al. (2016) to assist with the identification of slab gaps or windows. Near Alaska, we mapped the Aleutian slab and a detached slab that was previously identified as the `K slab' by Sigloch and Mihalynuk (2013). When unfolded these slabs apparently account for Pacific-Kula convergence towards Alaska since the late Cretaceous. We did not find evidence for a ridge subduction-related slab gap under the Alaskan region. Between northern Canada to California, we mapped the Juan de Fuca slab and several detached slabs at 1000 to 1500 km depths that were previously identified by Sigloch and Mihalynuk (2013). The velocity perturbations within our mapped slabs revealed slower P-wavespeed `slab gaps' under southernmost Alaska, Yukon, and British Columbia between the mapped Kula and Juan de Fuca plate. We did not find evidence of the hypothesized Resurrection plate. We compare our mapped slab gaps to predicted slab window geometries from previous studies and discuss their implications for plate tectonic reconstructions of the northern Cordillera and surrounding area.

  15. Dense and Dry Mantle Between the Continental Crust and the Oceanic Slab: Folding, Faulting and Tearing in the Slab in the Pampean Flat Slab, Southern Central Andes Evidenced by 3D Body Wave Tomography Along the 2015 Illapel, Chile Earthquake Rupture Area

    NASA Astrophysics Data System (ADS)

    Comte, D.; Farías, M.; Roecker, S. W.; Brandon, M. T.

    2017-12-01

    The 2015 Illapel interplate earthquake Mw 8.4 generated a large amount of aftershocks that was recorded by the Chile-Illapel Aftershock Experiment (CHILLAX) during a year after the mainshock. Using this database, along with previous seismological campaigns, an improved 3D body wave tomographic image was obtained, allowing us to visualize first-order lithospheric discontinuities. This new analysis confirms not only the presence of this dense block, but also that the Benioff zone extends with a 30° dip even below the 100 km depth, where the Nazca plate has been interpreted to be flat. Recent results of seismic anisotropy show that the oceanic plate has been detached at depths greater than 300 km. We propose that: i) The dry, cold mantle beneath the continental crust is an entrapped mantle, cooled by the slab flattening, while the western part would be hydrated by slab-derived fluid; ii) The Nazca plate would be faulted and is now subducting with a normal dip beneath the flattened slab segment. Considering that the slab segment is detached from deeper part of the subducted plate, slab pull on the flat segment would be reduced, decreasing its eastward advance. In the western side, the flat segment of the slab has been observed to be slightly folded. We propose that the current normal subduction is related to the slab break-off resulting from the loss of a slab-pull force, producing the accretion of the slab beneath the dry and cold mantle. Considering that the flat slab segment does not occur at depths shallower than 100 km, rollback of the slab is not expected. In turn, suction forces would have induced the shortening in the flat segment considering its eastward slowing down due to slab break-off, thus producing a breakthrough faulting. This proposition implies that the underplated flat slab segment, along with the overlying dense and dry mantle may be delaminated by gravitional instabilities and ablative subduction effects.

  16. A novel metal-organic coordination polymer with unprecedented floor-like structural configuration consisting of two kinds of independent building blocks of triple- and double-stranded braids

    NASA Astrophysics Data System (ADS)

    Che, Yun-Xia; Luo, Feng; Zheng, Ji-Min

    2007-02-01

    This paper presents a novel and distinctive metal-organic compound, {[Cd 4(bet) 4Cl 6(H 2O) 4][Cd 2Cl 6]} n (bet=(CH 3) 3NCH 2CO 2, namely betaine) 1, assembled from two independent building blocks of triple- and double-stranded braids, and characterized by an unprecedented floor-like structural configuration. Furthermore, IR, element analysis, and TG-DTA were employed to characterize it. Compound 1 belongs to triclinic system, space group P-1, a = 6.704(2) Å, b = 9.338(3) Å, c = 20.056(7) Å, α = 101.409(5)°, β = 96.650(5)°, γ = 93.148(5)°, V = 1218.5(7) Å 3, Z = 1, R1 = 0.0340, ωR2 = 0.1017.

  17. Long-life slab replacement concrete.

    DOT National Transportation Integrated Search

    2015-03-01

    This research was initiated following reports of high incidence of cracking on FDOT concrete pavement replacement : slab projects. Field slabs were instrumented for data acquisition from high-early-strength concrete pavement : replacement slabs place...

  18. Manipulation of enhanced absorption with tilted hexagonal boron nitride slabs

    NASA Astrophysics Data System (ADS)

    Wu, Xiaohu; Fu, Ceji

    2018-04-01

    The wavevector of electromagnetic wave propagation in a hexagonal boron nitride (hBN) slab can be controlled by tilting its optical axis. This property can be used to manipulate the absorption in a hBN slab. By carefully analyzing the dependence of the absorptivity of a thin hBN slab on the tilted angle of its optical axis, we propose a structure that can realize great absorptivity enhancement in a band by stacking hBN slabs of different tilted angles. Our numerical results show that the absorptivity of a structure made of 91 stacked hBN slabs can be achieved higher than 0.94 in the wavenumber range from 1367 to 1580 cm-1 when the tilted angles of the slabs are properly arranged. The strong absorption is attributed to the combination of impedance matching at the slab interfaces and enlarged wavevectors in the slabs. This work reveals a novel way to realize strong absorption with anisotropic materials for applications in areas such as thermal radiative energy harvesting and conversion.

  19. Subducted Slab Dynamics: Toward Understanding the Causes of Slab Stagnation

    NASA Astrophysics Data System (ADS)

    King, S. D.; Frost, D. J.; Rubie, D. C.

    2013-12-01

    The evolution and dynamics of subducted slabs are controlled by a number of factors, including rheology and composition. The correlation of the transformations from olivine to wadslayite and ringwoodite to perovskite plus magnesiowüstite with the seismic velocity discontinuities at 410 and 660 km depth, along with the density changes have been extensively investigated in terms of their impact on slab dynamics. Owing to the relatively smaller changes in density extending over a broader depth range, the impact of the pyroxene-garnet system has received less attention. Recent experimental work has found that the majorite component in garnet--a product of the transition from pyroxene into garnet--is one of the slowest-diffusing components in Earth's mantle. At the relatively low temperatures of the slab, this slow diffusion inhibits the dissolution of pyroxene into garnet, so that the slab remains buoyant relative to the ambient mantle and stagnates. We present dynamic subduction calculations that illustrate the effect of the non-equilibrium pyroxene to garnet transition on slab dynamics. If the transition between equilibrium and non-equilibrium behavior is below 1000 K, we find no impact on slab dynamics. If the transition occurs at 1200 K, it is enough to cause the slab to thicken and stagnate in the transition zone for an extended period of time. Our analysis suggests that cold slabs should be more likely to stagnate in the transition zone and we will compare a global compilation of slab geometries with slab thermal structure to evaluate.

  20. Design and application of a small size SAFT imaging system for concrete structure

    NASA Astrophysics Data System (ADS)

    Shao, Zhixue; Shi, Lihua; Shao, Zhe; Cai, Jian

    2011-07-01

    A method of ultrasonic imaging detection is presented for quick non-destructive testing (NDT) of concrete structures using synthesized aperture focusing technology (SAFT). A low cost ultrasonic sensor array consisting of 12 market available low frequency ultrasonic transducers is designed and manufactured. A channel compensation method is proposed to improve the consistency of different transducers. The controlling devices for array scan as well as the virtual instrument for SAFT imaging are designed. In the coarse scan mode with the scan step of 50 mm, the system can quickly give an image display of a cross section of 600 mm (L) × 300 mm (D) by one measurement. In the refined scan model, the system can reduce the scan step and give an image display of the same cross section by moving the sensor array several times. Experiments on staircase specimen, concrete slab with embedded target, and building floor with underground pipe line all verify the efficiency of the proposed method.

  1. Nuclear reactor building

    DOEpatents

    Gou, P.F.; Townsend, H.E.; Barbanti, G.

    1994-04-05

    A reactor building for enclosing a nuclear reactor includes a containment vessel having a wetwell disposed therein. The wetwell includes inner and outer walls, a floor, and a roof defining a wetwell pool and a suppression chamber disposed there above. The wetwell and containment vessel define a drywell surrounding the reactor. A plurality of vents are disposed in the wetwell pool in flow communication with the drywell for channeling into the wetwell pool steam released in the drywell from the reactor during a LOCA for example, for condensing the steam. A shell is disposed inside the wetwell and extends into the wetwell pool to define a dry gap devoid of wetwell water and disposed in flow communication with the suppression chamber. In a preferred embodiment, the wetwell roof is in the form of a slab disposed on spaced apart support beams which define there between an auxiliary chamber. The dry gap, and additionally the auxiliary chamber, provide increased volume to the suppression chamber for improving pressure margin. 4 figures.

  2. Nuclear reactor building

    DOEpatents

    Gou, Perng-Fei; Townsend, Harold E.; Barbanti, Giancarlo

    1994-01-01

    A reactor building for enclosing a nuclear reactor includes a containment vessel having a wetwell disposed therein. The wetwell includes inner and outer walls, a floor, and a roof defining a wetwell pool and a suppression chamber disposed thereabove. The wetwell and containment vessel define a drywell surrounding the reactor. A plurality of vents are disposed in the wetwell pool in flow communication with the drywell for channeling into the wetwell pool steam released in the drywell from the reactor during a LOCA for example, for condensing the steam. A shell is disposed inside the wetwell and extends into the wetwell pool to define a dry gap devoid of wetwell water and disposed in flow communication with the suppression chamber. In a preferred embodiment, the wetwell roof is in the form of a slab disposed on spaced apart support beams which define therebetween an auxiliary chamber. The dry gap, and additionally the auxiliary chamber, provide increased volume to the suppression chamber for improving pressure margin.

  3. Single-layer model to predict the source/sink behavior of diffusion-controlled building materials.

    PubMed

    Kumar, Deept; Little, John C

    2003-09-01

    Building materials may act as both sources of and sinks forvolatile organic compounds (VOCs) in indoor air. A strategy to characterize the rate of absorption and desorption of VOCs by diffusion-controlled building materials is validated. A previously developed model that predicts mass transfer between a flat slab of material and the well-mixed air within a chamber or room is extended. The generalized model allows a nonuniform initial material-phase concentration and a transient influent gas-phase concentration to be simultaneously considered. An analytical solution to the more general model is developed. Experimental data are obtained by placing samples of vinyl flooring inside a small stainless steel chamber and exposing them to absorption/desorption cycles of n-dodecane and phenol. Measured values for the material-air partition coefficient and the material-phase diffusion coefficient were obtained previously in a series of completely independent experiments. The a priori model predictions are in close agreement with the observed experimental data.

  4. FERROMANGANESE CRUST RESOURCES IN THE PACIFIC AND ATLANTIC OCEANS.

    USGS Publications Warehouse

    Commeau, R.F.; Clark, A.; Johnson, Chad; Manheim, F.T.; Aruscavage, P. J.; Lane, C.M.

    1984-01-01

    Ferromanganese crusts on raised areas of the ocean floor have joined abyssal manganese nodules and hydrothermal sulfides as potential marine resources. Significant volumes of cobalt-rich (about 1% Co) crusts have been identified to date within the US Exclusive Economic Zone (EEZ) in the Central Pacific: in the NW Hawaiian Ridge and Seamount region and in the seamounts in the Johnston Island and Palmyra Island regions. Large volumes of lower grade crusts, slabs, and nodules are also present in shallow ( greater than 1000 m) waters on the Blake plateau, off Florida-South Carolina in the Atlantic Ocean. Data on ferromanganese crusts have been increased by recent German and USGS cruises, but are still sparse, and other regions having crust potential are under current investigation. The authors discuss economic potentials for cobalt-rich crusts in the Central Pacific and Western North Atlantic oceans, with special reference to US EEZ areas. Additional research is needed before more quantitative resource estimates can be made.

  5. Measure Guideline: Implementing a Plenum Truss for a Compact Air Distribution System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burdick, A.

    2013-10-01

    This Measure Guideline presents the steps to implement a compact duct system inside an attic bulkhead (plenum truss) of a one-story, slab-on-grade (SOG) home. In a compact duct design, ductwork runs are reduced in length to yield a smaller and more compact duct system. Less energy will be lost through ductwork if the ducts are contained within the thermal enclosure of the house. These measures are intended for the production builder working to meet the 2012 International Energy Conservation Code (IECC) requirements and keep the ductwork within the thermal enclosure of the house. This measure of bringing the heating, ventilationmore » and air conditioning (HVAC) equipment and ductwork within the thermal enclosure of the house is appropriate for the builder wishing to avoid cathedralizing the insulation in the attic space (i.e., locating it at the underside of the roof deck rather than along the attic floor) or adding dropped soffits.« less

  6. Measure Guideline: Implementing a Plenum Truss for a Compact Air Distribution System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burdick, A.

    2013-10-01

    This Measure Guideline presents the steps to implement a compact duct system inside an attic bulkhead (plenum truss) of a one-story, slab-on-grade home. In a compact duct design, ductwork runs are reduced in length to yield a smaller and more compact duct system. Less energy will be lost through ductwork if the ducts are contained within the thermal enclosure of the house. These measures are intended for the production builder working to meet the 2012 International Energy Conservation Code (IECC) requirements and keep the ductwork within the thermal enclosure of the house. This measure of bringing the heating, ventilation andmore » air conditioning (HVAC) equipment and ductwork within the thermal enclosure of the house is appropriate for the builder wishing to avoid cathedralizing the insulation in the attic space (i.e., locating it at the underside of the roof deck rather than along the attic floor) or adding dropped soffits.« less

  7. Light Steel-Timber Frame with Composite and Plaster Bracing Panels

    PubMed Central

    Scotta, Roberto; Trutalli, Davide; Fiorin, Laura; Pozza, Luca; Marchi, Luca; De Stefani, Lorenzo

    2015-01-01

    The proposed light-frame structure comprises steel columns for vertical loads and an innovative bracing system to efficiently resist seismic actions. This seismic force resisting system consists of a light timber frame braced with an Oriented Strand Board (OSB) sheet and an external technoprene plaster-infilled slab. Steel brackets are used as foundation and floor connections. Experimental cyclic-loading tests were conduced to study the seismic response of two shear-wall specimens. A numerical model was calibrated on experimental results and the dynamic non-linear behavior of a case-study building was assessed. Numerical results were then used to estimate the proper behavior factor value, according to European seismic codes. Obtained results demonstrate that this innovative system is suitable for the use in seismic-prone areas thanks to the high ductility and dissipative capacity achieved by the bracing system. This favorable behavior is mainly due to the fasteners and materials used and to the correct application of the capacity design approach. PMID:28793642

  8. Radon measurement and mitigation activity in Finland.

    PubMed

    Valmari, T; Arvela, H; Reisbacka, H; Holmgren, O

    2014-07-01

    Radon prevention, measurement and mitigation activities have been increasing in Finland during the 2000s. Nowadays, many municipal authorities, especially those located in high-radon areas, require radon prevention measures. This has activated radon measurements. Owners of new houses having radon piping installed under the floor slab are the most active group to measure and reduce the found high-radon values. Their radon awareness is apparently better than on the average, and the existing piping makes it easier and cheaper to reduce the radon levels. Local campaigns involving invitation flyers mailed to the residents have been a cost-effective means to activate measurements of older houses. So far 116,611 dwellings in low-rise residential buildings have been measured. At least 15% of the 16,860 dwellings found to exceed the reference level of 400 Bq m(-3) had their indoor radon level reduced below that. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Light Steel-Timber Frame with Composite and Plaster Bracing Panels.

    PubMed

    Scotta, Roberto; Trutalli, Davide; Fiorin, Laura; Pozza, Luca; Marchi, Luca; De Stefani, Lorenzo

    2015-11-03

    The proposed light-frame structure comprises steel columns for vertical loads and an innovative bracing system to efficiently resist seismic actions. This seismic force resisting system consists of a light timber frame braced with an Oriented Strand Board (OSB) sheet and an external technoprene plaster-infilled slab. Steel brackets are used as foundation and floor connections. Experimental cyclic-loading tests were conduced to study the seismic response of two shear-wall specimens. A numerical model was calibrated on experimental results and the dynamic non-linear behavior of a case-study building was assessed. Numerical results were then used to estimate the proper behavior factor value, according to European seismic codes. Obtained results demonstrate that this innovative system is suitable for the use in seismic-prone areas thanks to the high ductility and dissipative capacity achieved by the bracing system. This favorable behavior is mainly due to the fasteners and materials used and to the correct application of the capacity design approach.

  10. Raetrad model extensions for radon entry into multi-level buildings with basements or crawl spaces.

    PubMed

    Nielson, K K; Rogers, V C; Rogers, V; Holt, R B

    1997-10-01

    The RAETRAD model was generalized to characterize radon generation and movement from soils and building materials into multi-level buildings with basements or crawl spaces. With the generalization, the model retains its original simplicity and ease of use. The model calculates radon entry rates that are consistent with measurements published for basement test structures at Colorado State University, confirming approximately equal contributions from diffusion and pressure-driven air flow at indoor-outdoor air pressure differences of deltaP(i-o) = -3.5 Pa. About one-fourth of the diffusive radon entry comes from concrete slabs and three-fourths comes from the surrounding soils. Calculated radon entry rates with and without a barrier over floor-wall shrinkage cracks generally agree with Colorado State University measurements when a sustained pressure of deltaP(i-o) = -2 Pa is used to represent calm wind (<1 m s(-1)) conditions. Calculated radon distributions in a 2-level house also are consistent with published measurements and equations.

  11. Effective Process Design for the Production of HIC-Resistant Linepipe Steels

    NASA Astrophysics Data System (ADS)

    Nieto, J.; Elías, T.; López, G.; Campos, G.; López, F.; Garcia, R.; De, Amar K.

    2013-09-01

    Production of slabs for sour service applications requires stringent control in slab internal quality and secondary processing so as to guarantee resistance against hydrogen-induced cracking (HIC). ArcelorMittal Steelmaking facility at Lazaro Cardenas, Mexico had recently implemented key steelmaking and casting processing technologies for production of sound, centerline free slabs for catering to the growing API Linepipe and off-shore market for sour service applications. State-of-the-art steelmaking with use of residual-free Direct-reduced Iron and continuous casting facilities with dynamic soft reduction were introduced for the production of slabs with ultra clean centerline. Introduction of controlled cooling of slabs for atomic hydrogen control well below 2 ppm has enabled production of slabs suitable for excellent HIC-resistant plate processing. Substantial tonnages of slabs were produced for production of API X52-X65 grade plates and pipes for sour service. Stringent quality control at each stage of steelmaking, casting, and slab inspection ensured slabs with excellent internal quality suitable for HIC resistance to be guaranteed in final product (Plates & Pipes). Details of production steps which resulted in successful HIC-resistant slab production have been described in this article.

  12. 0-6722 : spread prestressed concrete slab beam bridges.

    DOT National Transportation Integrated Search

    2014-08-01

    The Texas Department of Transportation uses : precast prestressed concrete slab beam bridges for : shorter-span bridges of approximately 3050 ft in : length. Conventional slab beam bridges have slab : beams placed immediately adjacent to one anoth...

  13. Flowing Air-Water Cooled Slab Nd: Glass Laser

    NASA Astrophysics Data System (ADS)

    Lu, Baida; Cai, Bangwei; Liao, Y.; Xu, Shifa; Xin, Z.

    1989-03-01

    A zig-zag optical path slab geometry Nd: glass laser cooled through flowing air-water is developed by us. Theoretical studies on temperature distribution of slab and rod configurations in the unsteady state clarify the advantages of the slab geometry laser. The slab design and processing are also reported. In our experiments main laser output characteristics, e. g. laser efficiency, polarization, far-field divergence angle as well as resonator misalignment are investigated. The slab phosphate glass laser in combination with a crossed Porro-prism resonator demonstrates a good laser performance.

  14. Distribution of slab-derived fluids around the edge of the Philippine Sea Plate from Central to Northeast Japan

    NASA Astrophysics Data System (ADS)

    Nakamura, Hitomi; Iwamori, Hikaru; Ishizuka, Osamu; Nishizawa, Tatsuji

    2018-01-01

    Marginal parts of a plate and subducting slab can play important roles in geodynamics. This is because in areas where a plate interacts with other plates or with the mantle thermal, geochemical, and mechanical interactions are expected. The Philippine Sea (PHS) slab that subducts beneath the Japan arcs has such an edge. To examine the relationship between arc magmatism and the slab edge in the transition zone from Northeast Japan to Central Japan, we investigated isotopic systematics of the regional volcanic rocks, incorporating data from literature and new data for five isotopic ratios of Sr, Nd, and Pb. The new data included major element compositions of 22 samples from the back-arc area, and 5 isotopic ratios for 6 samples selected from Pleistocene to early Quaternary epochs. Consequently, several findings were determined based on the spatial variation of the isotopic ratios and the estimated amount of slab-derived fluid: (1) the amount of fluid derived from the two subducting slabs (i.e., the Pacific slab and the PHS slab) decreases northward from a significantly high value ( 5 wt% fluid added to the source mantle), away from the seismically determined edge of the PHS slab; (2) the proportion of the PHS component in the total slab-derived fluid also decays northward; and (3) the PHS component spreads to the north beyond the seismically determined edge of the PHS slab. These observations strongly suggest that the existence of an aseismic PHS slab beneath southernmost parts of Northeast Japan delivers the PHS component to the arc magmatism. As was indicated by previous geodynamical studies, subduction of the PHS and PAC slabs may generate suction force towards the corner of mantle wedge, which might account for the large amount of fluid near the seismically determined slab edge as described in (1) above.

  15. Investigating Different Patterns of Slab Deformation in the Lower Mantle

    NASA Astrophysics Data System (ADS)

    Zhang, J.; McNamara, A. K.

    2017-12-01

    The geometry of slabs within the upper mantle have been relatively well-imaged by tomography and regional seismic studies; however, the style of slab deformation in the lower mantle remains poorly understood. Although tomography models reveal that the lower mantle beneath paleo-subduction regions are faster-than-average, the resolution is not high enough to resolve how slabs are actually deforming there. Slabs have long been hypothesized as viscous, tabular sheets that subduct at the surface, descend through the mantle, and impinge on the core-mantle boundary (CMB). Geodynamical studies have shown a wide range of possible deformational behaviors, ranging from stiff, buckling slabs to more-ductile masses of accumulating slab material undergoing pure shear. Of particular interest is how rheology and 3D spherical geometry control the shape and deformational style of slabs as they descend deeper into the mantle. We performed high resolution 3D spherical calculations to explore slab deformation in deep mantle as a function of slab strength. In our model, kinematic velocity boundary conditions are imposed on the surface to simulate a moving plate which guides the formation of a subducting slab. In addition, a viscosity jump at the transition zone is applied. We find that although a slab subducts as a large tabular sheet from the surface, it doesn't always maintain such geometry. Instead, it typically breaks apart into a few smaller and narrower sheets which can even turn into cylindrical-shaped downwelling after subducting into deep mantle. Since seismic anisotropy is hypothesized to originate from crystal preferred orientation (CPO) in a slab when it impinges on the CMB and is predicted with significant help of time-dependent deformation information from the geodynamic models, our findings on lower mantle slab deformation patterns may enhance the understanding towards the cause of characteristic patterns of predicted seismic anisotropy.

  16. Preface: Deep Slab and Mantle Dynamics

    NASA Astrophysics Data System (ADS)

    Suetsugu, Daisuke; Bina, Craig R.; Inoue, Toru; Wiens, Douglas A.

    2010-11-01

    We are pleased to publish this special issue of the journal Physics of the Earth and Planetary Interiors entitled "Deep Slab and Mantle Dynamics". This issue is an outgrowth of the international symposium "Deep Slab and Mantle Dynamics", which was held on February 25-27, 2009, in Kyoto, Japan. This symposium was organized by the "Stagnant Slab Project" (SSP) research group to present the results of the 5-year project and to facilitate intensive discussion with well-known international researchers in related fields. The SSP and the symposium were supported by a Grant-in-Aid for Scientific Research (16075101) from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government. In the symposium, key issues discussed by participants included: transportation of water into the deep mantle and its role in slab-related dynamics; observational and experimental constraints on deep slab properties and the slab environment; modeling of slab stagnation to constrain its mechanisms in comparison with observational and experimental data; observational, experimental and modeling constraints on the fate of stagnant slabs; eventual accumulation of stagnant slabs on the core-mantle boundary and its geodynamic implications. This special issue is a collection of papers presented in the symposium and other papers related to the subject of the symposium. The collected papers provide an overview of the wide range of multidisciplinary studies of mantle dynamics, particularly in the context of subduction, stagnation, and the fate of deep slabs.

  17. Orbiter fire rescue and crew escape training for EVA crew systems support

    NASA Image and Video Library

    1993-01-28

    Photos of orbiter fire rescue and crew escape training for extravehicular activity (EVA) crew systems support conducted in Bldg 9A Crew Compartment Trainer (CCT) and Fuel Fuselage Trainer (FFT) include views of CCT interior of middeck starboard fuselage showing middeck forward (MF) locker and COAS assembly filter, artiflex film and camcorder bag (26834); launch/entry suit (LES) helmet assembly, neckring and helmet hold-down assembly (26835-26836); middeck aft (MA) lockers (26837); area of middeck airlock and crew escape pole (26838); connectors of crew escape pole in the middeck (268390); three test subjects in LES in the flight deck (26840); emergency side hatch slide before inflated stowage (26841); area of below adjacent to floor panel MD23R (26842); a test subject in LES in the flight deck (26843); control board and also showing sign of "orbital maneuvering system (OMS) secure and OMS TK" (26844); test subject in the flight deck also showing chart of "ascent/abort summary" (26845).

  18. Spread prestressed concrete slab beam bridges.

    DOT National Transportation Integrated Search

    2015-04-01

    TxDOT uses prestressed slab beam bridges for short-span bridges ranging from approximately 3050 ft in : length. These bridges have precast, pretensioned slab beams placed immediately adjacent to one another : with a cast-in-place slab made composi...

  19. Modeling Slab-Slab Interactions: Dynamics of Outward Dipping Double-Sided Subduction Systems

    NASA Astrophysics Data System (ADS)

    Király, Ágnes; Holt, Adam F.; Funiciello, Francesca; Faccenna, Claudio; Capitanio, Fabio A.

    2018-03-01

    Slab-slab interaction is a characteristic feature of tectonically complex areas. Outward dipping double-sided subduction is one of these complex cases, which has several examples on Earth, most notably the Molucca Sea and Adriatic Sea. This study focuses on developing a framework for linking plate kinematics and slab interactions in an outward dipping subduction geometry. We used analog and numerical models to better understand the underlying subduction dynamics. Compared to a single subduction model, double-sided subduction exhibits more time-dependent and vigorous toroidal flow cells that are elongated (i.e., not circular). Because both the Molucca and Adriatic Sea exhibit an asymmetric subduction configuration, we also examine the role that asymmetry plays in the dynamics of outward dipping double-sided subduction. We introduce asymmetry in two ways; with variable initial depths for the two slabs ("geometric" asymmetry), and with variable buoyancy within the subducting plate ("mechanical" asymmetry). Relative to the symmetric case, we probe how asymmetry affects the overall slab kinematics, whether asymmetric behavior intensifies or equilibrates as subduction proceeds. While initial geometric asymmetry disappears once the slabs are anchored to the 660 km discontinuity, the mechanical asymmetry can cause more permanent differences between the two subduction zones. In the most extreme case, the partly continental slab stops subducting due to the unequal slab pull force. The results show that the slab-slab interaction is most effective when the two trenches are closer than 10-8 cm in the laboratory, which is 600-480 km when scaled to the Earth.

  20. Experimental and finite element study of ultimate strength of continuous composite concrete slabs with steel decking

    NASA Astrophysics Data System (ADS)

    Gholamhoseini, Alireza

    2018-03-01

    Composite one-way concrete slabs with profiled steel decking as permanent formwork are commonly used in the construction industry. The steel decking supports the wet concrete of a cast in situ reinforced or post-tensioned concrete slab and, after the concrete sets, acts as external reinforcement. In this type of slab, longitudinal shear failure between the concrete and the steel decking is the most common type of failure at the ultimate load stage. Design codes require the experimental evaluation of the ultimate load capacity and longitudinal shear strength of each type of steel decking using full-scale tests on simple-span slabs. There is also no procedure in current design codes to evaluate the ultimate load capacity and longitudinal shear strength of continuous composite slabs and this is often assessed experimentally by full-scale tests. This paper presents the results of three full-scale tests up to failure on continuous composite concrete slabs cast with trapezoidal steel decking profile (KF70) that is widely used in Australia. Slab specimens were tested in four-point bending at each span with shear spans of span/4. The longitudinal shear failure of each slab is evaluated and the measured mid-span deflection, the end slip and the mid-span steel and concrete strains are also presented and discussed. Redistribution of bending moment in each slab is presented and discussed. A finite element model is proposed and verified by experimental data using interface element to model the bond properties between steel decking and concrete slab and investigate the ultimate strength of continuous composite concrete slabs.

  1. An imbalance in the deep water cycle at subduction zones: The potential importance of the fore-arc mantle

    NASA Astrophysics Data System (ADS)

    Ribeiro, Julia M.; Lee, Cin-Ty A.

    2017-12-01

    The depth of slab dehydration is thought to be controlled by the thermal state of the downgoing slab: cold slabs are thought to mostly dehydrate beneath the arc front while warmer slabs should mostly dehydrate beneath the fore-arc. Cold subduction zone lavas are thus predicted to have interacted with greater extent of water-rich fluids released from the downgoing slab, and should thus display higher water content and be elevated in slab-fluid proxies (i.e., high Ba/Th, H2O/Ce, Rb/Th, etc.) compared to hot subduction zone lavas. Arc lavas, however, display similar slab-fluid signatures regardless of the thermal state of the slab, suggesting more complexity to volatile cycling in subduction zones. Here, we explore whether the serpentinized fore-arc mantle may be an important fluid reservoir in subduction zones and whether it can contribute to arc magma generation by being dragged down with the slab. Using simple mass balance and fluid dynamics calculations, we show that the dragged-down fore-arc mantle could provide enough water (∼7-78% of the total water injected at the trenches) to account for the water outfluxes released beneath the volcanic arc. Hence, we propose that the water captured by arc magmas may not all derive directly from the slab, but a significant component may be indirectly slab-derived via dehydration of dragged-down fore-arc serpentinites. Fore-arc serpentinite dehydration, if universal, could be a process that explains the similar geochemical fingerprint (i.e., in slab fluid proxies) of arc magmas.

  2. Deformation of the Tonga Slab: Evidence for Interaction with a Small-scale Secondary Plume in the Transition Zone

    NASA Astrophysics Data System (ADS)

    Billen, M. I.; Bikoba, J. Z.; Tarlow, S.

    2015-12-01

    Magali I. Billen and John Z. BikobaThe Tonga Slab is the most seismically active subduction zone providing a uniquely detailed picture of the internal deformation of the slab, with apparent warping and folding, from the surface through the transition zone. Here, we investigate the dynamical origin of a irregular feature in the seismicity within the transition zone located at 21-28oS, using 3D visualization and analysis of the seismicity and compression/tension (P/T) axis from the moment tensor solutions to characterize the geometry of, and the orientation of forces acting on, the slab. This irregular feature can be described as narrow region of upward deflection of the slab, with a gap in seismicity beyond (down-dip of) the deflected region, and flanked by two narrow V-shaped gaps in seismicity suggestive of tearing of the slab. The P/T axis show a dominate down-dip orientation of the P axis above the deflection point, which rotate to a nearly vertical orientation within the central region of the deflected slab. The adjacent attached regions (down-dip of the two flanking slab gaps) also have rotated and more heterogeneous P/T axis orientations. In contrast, the adjacent section of the slab to the north of 21oS has continuous seismicity throughout the transition zone, with a roughly uniform planar shape, and generally down-dip orientation of the P axis. We explore three possible hypothesis for the observed deformation including: 1) deflection due to a buoyant metastable olivine wedge, 2) a buckling feature in the slab as previously proposed by Myhill (GJI., 2013), and interaction with a small-scale, secondary plume upwelling below the slab. If the newly-observed gaps in seismicity indicate physical gaps or significant thinning of the slab, then these observations are not consistent with the buckling hypothesis. The lack of significant along-strike variation in slab age or subduction rate also suggests that a localized region of metastable olivine is unlikely. Therefore, we test the third hypothesis using a simple 3D geodynamical model of a planar dipping slab overlying a localized buoyant upwelling (radius < 150 km). We present comparisons of the observations to the model predictions for the subsequent deformation of the slab and orientations of principal stress axis within the slab.

  3. The icosahedral RNA virus as a grotto: organizing the genome into stalagmites and stalactites.

    PubMed

    Harvey, Stephen C; Zeng, Yingying; Heitsch, Christine E

    2013-03-01

    There are two important problems in the assembly of small, icosahedral RNA viruses. First, how does the capsid protein select the viral RNA for packaging, when there are so many other candidate RNA molecules available? Second, what is the mechanism of assembly? With regard to the first question, there are a number of cases where a particular RNA sequence or structure--often one or more stem-loops--either promotes assembly or is required for assembly, but there are others where specific packaging signals are apparently not required. With regard to the assembly pathway, in those cases where stem-loops are involved, the first step is generally believed to be binding of the capsid proteins to these "fingers" of the RNA secondary structure. In the mature virus, the core of the RNA would then occupy the center of the viral particle, and the stem-loops would reach outward, towards the capsid, like stalagmites reaching up from the floor of a grotto towards the ceiling. Those viruses whose assembly does not depend on protein binding to stem-loops could have a different structure, with the core of the RNA lying just under the capsid, and the fingers reaching down into the interior of the virus, like stalactites. We review the literature on these alternative structures, focusing on RNA selectivity and the assembly mechanism, and we propose experiments aimed at determining, in a given virus, which of the two structures actually occurs.

  4. Flexural performance of steel fiber reinforced concrete (SFRC) ribbed slab with various topping thicknesses

    NASA Astrophysics Data System (ADS)

    Rahman, Fadhillah Abdul; Bakar, Afidah Abu; Hashim, Mohd Hisbany Mohd; Ahmad, Hazrina

    2017-11-01

    Ribbed slab provides lighter slab than an equivalent solid slab which helps in reducing the weight with its voids. However, in order to overcome the drawbacks in the construction process, the application of steel fibre reinforcement concrete (SFRC) is seen as an alternative material to be used in the slab. This study is performed to investigate the behaviour of SFRC as the main material in ribbed slab, omitting the conventional reinforcements, under four-point bending test. Three equivalent samples of ribbed slabs were prepared for this study with variations in the topping thickness of 100, 75 and 50 mm. The flexural strength of ribbed slab with 100 mm topping shows similar loading carrying capacity with the 75mm topping while 50 mm gave the lowest ultimate loading. First cracks for all slabs occurred at the topping. The cracks began from the external ribs and propagates toward the internal rib. Incorporation of steel fibres help in giving a longer deflection softening than a sudden brittle failure, thus proves its ability to increase energy absorption capacity and improving cracking behaviour.

  5. South-American plate advance and forced Andean trench retreat as drivers for transient flat subduction episodes.

    PubMed

    Schepers, Gerben; van Hinsbergen, Douwe J J; Spakman, Wim; Kosters, Martha E; Boschman, Lydian M; McQuarrie, Nadine

    2017-05-16

    At two trench segments below the Andes, the Nazca Plate is subducting sub-horizontally over ∼200-300 km, thought to result from a combination of buoyant oceanic-plateau subduction and hydrodynamic mantle-wedge suction. Whether the actual conditions for both processes to work in concert existed is uncertain. Here we infer from a tectonic reconstruction of the Andes constructed in a mantle reference frame that the Nazca slab has retreated at ∼2 cm per year since ∼50 Ma. In the flat slab portions, no rollback has occurred since their formation at ∼12 Ma, generating 'horse-shoe' slab geometries. We propose that, in concert with other drivers, an overpressured sub-slab mantle supporting the weight of the slab in an advancing upper plate-motion setting can locally impede rollback and maintain flat slabs until slab tearing releases the overpressure. Tear subduction re-establishes a continuous slab and allows the process to recur, providing a mechanism for the transient character of flat slabs.

  6. How to measure slab-off and reverse slab prism in spectacle lenses.

    PubMed

    Christoff, Alexander; Guyton, David L

    2007-08-01

    It is well known that new spectacle lenses for the correction of anisometropia can induce diplopia with reading. The difference in the powers of the lenses induces a net prismatic effect that can cause double vision through off-center areas of the lenses. This is particularly bothersome when patients try to read, often noting vertical double vision in attempted downgaze, especially through multifocal add segments. This induced prismatic effect can be compensated at one level of downgaze by the use of slab-off or reverse slab prism. Typically the slab-off correction is ground into the stronger minus, or weaker plus lens. Reverse slab is ground into the weaker minus, or stronger plus, lens. Unfortunately, determining the amount of slab-off prism already incorporated into spectacle lenses is nonintuitive and inconvenient. This usually requires the use of a lens clock, which is not widely accessible to many ophthalmology practices. A simple technique, described in the past but poorly known, is illustrated here for quickly measuring slab-off and reverse slab prism prescription lenses in the clinic with a common manual lens meter.

  7. PIONEER VENUS 2 MULTI-PROBE PARACHUTE TESTS IN THE VEHICLE ASSEMBLY BUILDING

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A parachute system, designed to carry an instrument-laden probe down through the dense atmosphere of torrid, cloud-shrouded Venus, was tested in KSC's Vehicle Assembly Building. The tests are in preparation for a Pioneer multi-probe mission to Venus scheduled for launch from KSC in 1978. Full-scale (12-foot diameter) parachutes with simulated pressure vessels weighing up to 45 pounds were dropped from heights of up to 450 feet tot he floor of the VAB where the impact was cushioned by a honeycomb cardboard impact arrestor. The VAB offers an ideal, wind-free testing facility at no additional construction cost and was used for similar tests of the parachute system for the twin Viking spacecraft scheduled for launch toward Mars in August.

  8. Metastable mantle phase transformations and deep earthquakes in subducting oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Kirby, Stephen H.; Stein, Seth; Okal, Emile A.; Rubie, David C.

    1996-05-01

    Earth's deepest earthquakes occur as a population in subducting or previously subducted lithosphere at depths ranging from about 325 to 690 km. This depth interval closely brackets the mantle transition zone, characterized by rapid seismic velocity increases resulting from the transformation of upper mantle minerals to higher-pressure phases. Deep earthquakes thus provide the primary direct evidence for subduction of the lithosphere to these depths and allow us to investigate the deep thermal, thermodynamic, and mechanical ferment inside slabs. Numerical simulations of reaction rates show that the olivine → spinel transformation should be kinetically hindered in old, cold slabs descending into the transition zone. Thus wedge-shaped zones of metastable peridotite probably persist to depths of more than 600 km. Laboratory deformation experiments on some metastable minerals display a shear instability called transformational faulting. This instability involves sudden failure by localized superplasticity in thin shear zones where the metastable host mineral transforms to a denser, finer-grained phase. Hence in cold slabs, such faulting is expected for the polymorphic reactions in which olivine transforms to the spinel structure and clinoenstatite transforms to ilmenite. It is thus natural to hypothesize that deep earthquakes result from transformational faulting in metastable peridotite wedges within cold slabs. This consideration of the mineralogical states of slabs augments the traditional largely thermal view of slab processes and explains some previously enigmatic slab features. It explains why deep seismicity occurs only in the approximate depth range of the mantle transition zone, where minerals in downgoing slabs should transform to spinel and ilmenite structures. The onset of deep shocks at about 325 km is consistent with the onset of metastability near the equilibrium phase boundary in the slab. Even if a slab penetrates into the lower mantle, earthquakes should cease at depths near 700 km, because the seismogenic phase transformations in the slab are completed or can no longer occur. Substantial metastability is expected only in old, cold slabs, consistent with the observed restriction of deep earthquakes to those settings. Earthquakes should be restricted to the cold cores of slabs, as in any model in which the seismicity is temperature controlled, via the distribution of metastability. However, the geometries of recent large deep earthquakes pose a challenge for any such models. Transformational faulting may give insight into why deep shocks lack appreciable aftershocks and why their source characteristics, including focal mechanisms indicating localized shear failure rather than implosive deformation, are so similar to those of shallow earthquakes. Finally, metastable phase changes in slabs would produce an internal source of stress in addition to those due to the weight of the sinking slab. Such internal stresses may explain the occurrence of earthquakes in portions of lithosphere which have foundered to the bottom of the transition zone and/or are detached from subducting slabs. Metastability in downgoing slabs could have considerable geodynamic significance. Metastable wedges would reduce the negative buoyancy of slabs, decrease the driving force for subduction, and influence the state of stress in slabs. Heat released by metastable phase changes would raise temperatures within slabs and facilitate the transformation of spinel to the lower mantle mineral assemblage, causing slabs to equilibrate more rapidly with the ambient mantle and thus contribute to the cessation of deep seismicity. Because wedge formation should occur only for fast subducting slabs, it may act as a "parachute" and contribute to regulating plate speeds. Wedge formation would also have consequences for mantle evolution because the density of a slab stagnated near the bottom of the transition zone would increase as it heats up and the wedge transforms to denser spinel, favoring the subsequent sinking of the slab into the lower mantle.

  9. Dimensional stability of concrete slabs on grade.

    DOT National Transportation Integrated Search

    2012-10-01

    Drying shrinkage is one of the major causes of cracking in concrete slabs on grade. The moisture : difference between the top and bottom surface of the slabs causes a dimensional or shrinkage gradient : to develop through the depth of the slabs...

  10. Thermal buoyancy on Venus - Underthrusting vs subduction

    NASA Technical Reports Server (NTRS)

    Burt, Jeffrey D.; Head, James W.

    1992-01-01

    The thermal and buoyancy consequences of the subduction endmember are modeled in an attempt to evaluate the conditions distinguishing underthrusting and subduction. Thermal changes in slabs subducting into the Venusian mantle with a range of initial geotherms are used to predict density changes and, thus, slab buoyancy. Based on a model for subduction-induced mantle flow, it is then argued that the angle of the slab dip helps differentiate between underthrusting and subduction. Mantle flow applies torques to the slab which, in combination with torques due to slab buoyancy, act to change the angle of slab dip.

  11. Tectonic evolution of the Mexico flat slab and patterns of intraslab seismicity.

    NASA Astrophysics Data System (ADS)

    Moresi, L. N.; Sandiford, D.

    2017-12-01

    The Cocos plate slab is horizontal for about 250 km beneath the Guerrero region of southern Mexico. Analogous morphologies can spontaneously develop in subduction models, through the presence of a low-viscosity mantle wedge. The Mw 7.1 Puebla earthquake appears to have ruptured the inboard corner of the Mexican flat slab; likely in close proximity to the mantle wedge corner. In addition to the historical seismic record, the Puebla earthquake provides a valuable constraint through which to assess geodynamic models for flat slab evolution. Slab deformation predicted by the "weak wedge" model is consistent with past seismicity in the both the upper plate and slab. Below the flat section, the slab is anomalously warm relative to its depth; the lack of seismicity in the deeper part of the slab fits the global pattern of temperature-controlled slab seismicity. This has implications for understanding the deeper structure of the slab, including the seismic hazard from source regions downdip of the Puebla rupture (epicenters closer to Mexico City). While historical seismicity provides a deformation pattern consistent with the weak wedge model , the Puebla earthquake is somewhat anomalous. The earthquake source mechanism is consistent with stress orientations in our models, however it maps to a region of relatively low deviatoric stress.

  12. Heat-flow measurements at shot points along the 1978 Saudi Arabia seismic deep-refraction line; Part II, Discussion and interpretation

    USGS Publications Warehouse

    Gettings, M.E.

    1982-01-01

    The heat-flow profile across the Arabian Shield from Ar Riyad to Ad Darb and across the Red Sea is examined for compatibility with the lithospheric structure of the area as deduced from geologic and other geophysical data. Broad continental uplift associated with Red Sea rifting is symmetric about the Red Sea axis, and geologic and geochronologic evidence indicate that uplift has occurred mainly in the interval 25-13 Ma (mega-annum) ago. Thermal-profile changes in the upper mantle resulting from an influx of hot material associated with rifting yield the correct order of magnitude of uplift, and this mechanism is suggested as the explanation for the regional doming. A lithospheric section, constructed from seismic refraction, gravity, and regional geologic data, provides the framework for construction of thermal models. Thermal gradient measurements were made in drill holes at five shot points. Geotherms for the Shield, which assume a radiogenic heat-source distribution that decreases exponentially with depth, yield temperatures of about 450?C at a depth of 40 km (base of the crust) for shot points 2 (Sabhah) and 3. The geotherm for shot point 4 (near Bishah) yields a distinctly higher temperature (about 580?C) for the same depth. Static models used to model the heat flow in the oceanic crust of the Red Sea shelf and coastal plain either yield too small a heat flow to match the observed heat flow or give lithosphere thicknesses that are so thin as to be improbable. Dynamic (solid-state accretion) models, which account for mantle flow at the base of the lithosphere, adequately match the observed heat-flow values. In the deep-water trough of the Red Sea, which is presently undergoing active sea-floor spreading, classical models of heat flow for a moving slab with accretion at the spreading center are adequate to explain the average heat-flow level. At shot point 5 (Ad Darb), the anomalous heat flow of 2 HFU (heat-flow units) can be explained in terms of a Shield component (0.8-1.0 HFU) and a component related to heating by the abutting oceanic crust a few kilometers away for periods exceeding 10 Ma. Analytical results are included for: 1) the cooling of a static sheet with an initial temperature distribution characteristic of a moving slab in a sea-floor spreading environment, and 2) the heating of a homogeneous quarter-space at its vertical boundary.

  13. Is the Ordos Basin floored by a trapped oceanic plateau?

    NASA Astrophysics Data System (ADS)

    Kusky, Tim; Mooney, Walter

    2015-11-01

    The Ordos Basin in China has about 10 km of Neoarchean to Quaternary sediments covering an enigmatic basement of uncertain origin. The basement is tectonically stable, has a thick mantle root, low heat flow, few earthquakes, and has been slowly subsiding for billions of years. The basement has geophysical signatures that indicate it is dominantly intermediate to mafic in composition, and is similar to some other cratons world-wide, and also to several major oceanic plateaus. It was accreted to the amalgamated Eastern Block and Central Orogenic belt of the North China Craton (NCC) in the Paleoproterozoic, then involved in several Proterozoic tectonic events including being over-thrust by an accretionary orogen, and intruded by Andean arc-related magmas, and then involved in a continent-continent collision during amalgamation with the Columbia Supercontinent. Thus, the basement rocks are deformed, metamorphosed to granulite facies, and determining their initial origin is difficult. We suggest that the data is consistent with an origin as an oceanic plateau that accreted to the NCC and, later experienced different episodes of differentiation associated with later subduction and collisions. Formation of cratonic lithosphere by accretion of oceanic plateaus may be one mechanism to create stable cratons. Other cratons that apparently formed by partial melting of underplated and imbricated oceanic slabs are stable in some cases, but also re-activated and ;de-cratonized; in some cases in Asia, where they have been affected by younger subduction, hydration, slab roll-back, and melt-peridotite reactions. This suggests that the initial mode of craton formation may be a factor in the preservation of stable cratons, and de-cratonization is not only influenced by younger tectonic activity.

  14. Current wheeze, asthma, respiratory infections, and rhinitis among adults in relation to inspection data and indoor measurements in single-family houses in Sweden-The BETSI study.

    PubMed

    Wang, J; Engvall, K; Smedje, G; Nilsson, H; Norbäck, D

    2017-07-01

    In the Swedish Building Energy, Technical Status and Indoor environment study, a total of 1160 adults from 605 single-family houses answered a questionnaire on respiratory health. Building inspectors investigated the homes and measured temperature, air humidity, air exchange rate, and wood moisture content (in attic and crawl space). Moisture load was calculated as the difference between indoor and outdoor absolute humidity. Totally, 7.3% were smokers, 8.7% had doctor' diagnosed asthma, 11.2% current wheeze, and 9.5% current asthma symptoms. Totally, 50.3% had respiratory infections and 26.0% rhinitis. The mean air exchange rate was 0.36/h, and the mean moisture load 1.70 g/m 3 . Damp foundation (OR=1.79, 95% CI 1.16-2.78) was positively associated while floor constructions with crawl space (OR=0.49, 95% CI 0.29-0.84) was negatively associated with wheeze. Concrete slabs with overlying insulation (OR=2.21, 95% CI 1.24-3.92) and brick façade (OR=1.71, 95% CI 1.07-2.73) were associated with rhinitis. Moisture load was associated with respiratory infections (OR=1.21 per 1 g/m 3 , 95% CI 1.04-1.40) and rhinitis (OR=1.36 per 1 g/m 3 , 95% CI 1.02-1.83). Air exchange rate was associated with current asthma symptoms (OR=0.85 per 0.1/h, 95% CI 0.73-0.99). Living in homes with damp foundation, concrete slabs with overlying insulation, brick façade, low ventilation flow, and high moisture load are risk factors for asthma, rhinitis, and respiratory infections. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Technical - Economic Research for Passive Buildings

    NASA Astrophysics Data System (ADS)

    Miniotaite, Ruta

    2017-10-01

    A newly constructed passive house must save 80 % of heat resources; otherwise it is not a passive house. The heating energy demand of a passive building is less than 15 kWh/m2 per year. However, a passive house is something more than just an energy-saving house. This concept involves sustainable, high-quality, valuable, healthy and durable construction. Features of a passive house: high insulation of envelope components, high-quality windows, good tightness of the building, regenerative ventilation system and elimination of thermal bridges. The Energy Performance of Buildings Directive (EPBD) 61 requires all new public buildings to become near-zero energy buildings by 2019 and will be extended to all new buildings by 2021. This concept involves sustainable, high-quality, valuable, healthy and durable construction. Foundation, walls and roofs are the most essential elements of a house. The type of foundation for a private house is selected considering many factors. The article examines technological and structural solutions for passive buildings foundation, walls and roofs. The technical-economic comparison of the main structures of a passive house revealed that it is cheaper to install an adequately designed concrete slab foundation than to build strip or pile foundation and the floor separately. Timber stud walls are the cheapest wall option for a passive house and 45-51% cheaper compared to other options. The comparison of roofs and ceilings showed that insulation of the ceiling is 25% more efficient than insulation of the roof. The comparison of the main envelope elements efficiency by multiple-criteria evaluation methods showed that it is economically feasible to install concrete slab on ground foundation, stud walls with sheet cladding and a pitched roof with insulated ceiling.

  16. Field evaluation of alternative and cost efficient bridge approach slabs.

    DOT National Transportation Integrated Search

    2013-11-01

    Based on a recent study on cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et al. 2010) has recommended : three new BAS designs for possible implementation by MoDOT namely a) 20 feet cast-inplace slab with sleeper slab (CIP...

  17. Cenozoic tectonics of western North America controlled by evolving width of Farallon slab.

    PubMed

    Schellart, W P; Stegman, D R; Farrington, R J; Freeman, J; Moresi, L

    2010-07-16

    Subduction of oceanic lithosphere occurs through two modes: subducting plate motion and trench migration. Using a global subduction zone data set and three-dimensional numerical subduction models, we show that slab width (W) controls these modes and the partitioning of subduction between them. Subducting plate velocity scales with W(2/3), whereas trench velocity scales with 1/W. These findings explain the Cenozoic slowdown of the Farallon plate and the decrease in subduction partitioning by its decreasing slab width. The change from Sevier-Laramide orogenesis to Basin and Range extension in North America is also explained by slab width; shortening occurred during wide-slab subduction and overriding-plate-driven trench retreat, whereas extension occurred during intermediate to narrow-slab subduction and slab-driven trench retreat.

  18. Subducting Slabs: Jellyfishes in the Earth's Mantle

    NASA Astrophysics Data System (ADS)

    Loiselet, C.; Braun, J.; Husson, L.; Le Carlier de Veslud, C.; Thieulot, C.; Yamato, P.; Grujic, D.

    2010-12-01

    The constantly improving resolution of geophysical data, seismic tomography and seismicity in particular, shows that the lithosphere does not subduct as a slab of uniform thickness but is rather thinned in the upper mantle and thickened around the transition zone between the upper and lower mantle. This observation has traditionally been interpreted as evidence for the buckling and piling of slabs at the boundary between the upper and lower mantle, where a strong contrast in viscosity may exist and cause resistance to the penetration of slabs into the lower mantle. The distribution and character of seismicity reveal, however, that slabs undergo vertical extension in the upper mantle and compression near the transition zone. In this paper, we demonstrate that during the subduction process, the shape of low viscosity slabs (1 to 100 times more viscous than the surrounding mantle) evolves toward an inverted plume shape that we coin jellyfish. Results of a 3D numerical model show that the leading tip of slabs deform toward a rounded head skirted by lateral tentacles that emerge from the sides of the jellyfish head. The head is linked to the body of the subducting slab by a thin tail. A complete parametric study reveals that subducting slabs may achieve a variety of shapes, in good agreement with the diversity of natural slab shapes evidenced by seismic tomography. Our work also suggests that the slab to mantle viscosity ratio in the Earth is most likely to be lower than 100. However, the sensitivity of slab shapes to upper and lower mantle viscosities and densities, which remain poorly constrained by independent evidence, precludes any systematic deciphering of the observations.

  19. Subducting slabs: Jellyfishes in the Earth's mantle

    NASA Astrophysics Data System (ADS)

    Loiselet, Christelle; Braun, Jean; Husson, Laurent; Le Carlier de Veslud, Christian; Thieulot, Cedric; Yamato, Philippe; Grujic, Djordje

    2010-08-01

    The constantly improving resolution of geophysical data, seismic tomography and seismicity in particular, shows that the lithosphere does not subduct as a slab of uniform thickness but is rather thinned in the upper mantle and thickened around the transition zone between the upper and lower mantle. This observation has traditionally been interpreted as evidence for the buckling and piling of slabs at the boundary between the upper and lower mantle, where a strong contrast in viscosity may exist and cause resistance to the penetration of slabs into the lower mantle. The distribution and character of seismicity reveal, however, that slabs undergo vertical extension in the upper mantle and compression near the transition zone. In this paper, we demonstrate that during the subduction process, the shape of low viscosity slabs (1 to 100 times more viscous than the surrounding mantle) evolves toward an inverted plume shape that we coin jellyfish. Results of a 3D numerical model show that the leading tip of slabs deform toward a rounded head skirted by lateral tentacles that emerge from the sides of the jellyfish head. The head is linked to the body of the subducting slab by a thin tail. A complete parametric study reveals that subducting slabs may achieve a variety of shapes, in good agreement with the diversity of natural slab shapes evidenced by seismic tomography. Our work also suggests that the slab to mantle viscosity ratio in the Earth is most likely to be lower than 100. However, the sensitivity of slab shapes to upper and lower mantle viscosities and densities, which remain poorly constrained by independent evidence, precludes any systematic deciphering of the observations.

  20. Slab edge interaction with a back-arc spreading center: 3D instantaneous mantle flow models of Vanuatu, SW Pacific

    NASA Astrophysics Data System (ADS)

    McLean, K. A.; Jadamec, M.; Durance-Sie, P. M.; Moresi, L. N.

    2011-12-01

    The Vanuatu area of the south-west Pacific is a dynamic region of high heat-flow and strain-rate, dominated by ongoing plate boundary processes. At the southern termination of the Vanuatu arc the curved geometry of the New Hebrides trench juxtaposes the slab edge perpendicular to its back-arc spreading center. While existing 3D subduction models have demonstrated the importance of mantle flow around a slab edge, the nature of interaction between back-arc upwelling and circum-slab edge mantle flow is not well understood. We use 3D instantaneous numerical models of a Newtonian mantle rheology to test the effect of the slab edge and back-arc upwelling on the mantle flow vector field beneath southern Vanuatu. These high-resolution models simulate temperature-dependent buoyancy-driven deformation of the lithosphere and mantle for a realistic slab geometry. Model results show a small but significant component of vertical mantle flow velocity associated with the slab edge and back-arc spreading center. We also see strain-rate and dynamic topography commensurate with surface observations. Mantle flow by toroidal-type motion brings hotter mantle material from behind the slab into the mantle wedge, elevating geothermal gradients in the slab edge vicinity. The implications of moderate vertical displacement of this hot mantle material at the slab edge are wide-ranging, and such a tectonic framework might aid interpretation of a number of surface observations. For example, induced decompression partial-melting in the mantle wedge and/or slab, and thermal erosion of the slab may contribute to the diverse magma compositions from this region.

  1. Spring and Summer Changes at the South Pole as Seen by the Mars Orbiter Camera

    NASA Technical Reports Server (NTRS)

    Ingersoll, A. P.; Murray, B. C.; Byrne, S.; DeJong, E.; Danielson, G. E.; Herkenhoff, K. E.; Kieffer, H. H.; Soderblom, L. A.

    2000-01-01

    The Mars Orbiter Camera (MOC) on the Mars Global Surveyor (MGS) spacecraft has been able to follow individual features as the CO2 frost disappears and exposes the material underneath. Because the orbit of MGS is inclined at an angle of 93 degrees relative to the equator, the spacecraft gets especially good coverage of the ring at 87 degrees latitude. The following is a list of phenomena that have been seen during the spring and summer at the South Pole: (1) Circular depressions that are approximately ten meters deep and hundreds of meters in diameter. They are found only within the residual polar cap, the part that survives the summer. The high areas between the depressions are flat-topped mesas whose sides are concave circular arcs. In some places the depressions form patterns that exhibit north-south symmetry, suggesting some control by sunlight; (2) Dark layers that are exposed on the walls of the mesas. Each layer is at most a few meters thick. The dark layers might accumulate during climatic episodes of high atmospheric dust content, or they might accumulate during the annual cycling of dusty CO2; (3) Albedo differences that develop during the summer within the residual cap. These include subtle darkening of the floors of the depressions relative to the mesas and occasional major darkening of the floors, especially near the edge of the cap. The floors and mesas form a distinct stratum, suggesting they represent a distinct compositional boundary. For instance the floors may be water and the mesas may be CO2; (4) Small dark features that appear in spring on the seasonal frost outside the residual cap. Some of the features have parallel tails that are clearly shaped by the wind. Others are more symmetric, like dark snowflakes, with multiple branching arms. After the CO2 frost has disappeared the arms are seen as troughs and the centers as topographic lows; (5) Polygons whose sides are dark troughs. Those that are outside the residual cap seem to disappear when the frost disappears. The polygons and the dark snowflakelike structures may be related, and suggest that CO2 frost may form cohesive slabs; (6) Irregular depressions outside the residual cap. They look like degraded versions of the circular depressions inside the residual cap, and may be a remnant of the cap's changing location; and (7) Areas of burial and exhumation of circular depressions. Thomas et al. give an example with a sharp boundary: On one side the depressions are buried and on the other side they are exposed. In other cases there are rounded troughs up to one kilometer wide, which are dark in summer and appear to have eroded down below the floor of the circular depressions.

  2. STS-30 Magellan spacecraft processing at Kennedy Space Center (KSC) SAEF-2

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Magellan spacecraft is hoisted from the transport trailer of the Payload Environmental Transportation System (PETS) to the floor of the clean room in the Space Assembly and Encapsulation Facility 2 (SAEF-2) at Kennedy Space Center (KSC). Clean-suited technicians guide Magellan into place. The spacecraft, destined for unprecedented studies of Venusian topographic features, will be deployed by the crew of NASA's STS-30 mission in April 1989. View provided by KSC with alternate number KSC-88PC-1084.

  3. KSC-2009-2465

    NASA Image and Video Library

    2009-04-01

    CAPE CANAVERAL, Fla. – In High Bay 4 of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, a large crane moves the Ares I-X upper stage simulator service module/service adapter segment toward a stand. Other segments are placed and stacked on the floor around it. Ares I-X is the test vehicle for the Ares I, which is part of the Constellation Program to return men to the moon and beyond. The Ares I-X is targeted for launch in July 2009. Photo credit: NASA/Kim Shiflett

  4. KSC-2009-2467

    NASA Image and Video Library

    2009-04-01

    CAPE CANAVERAL, Fla. – In High Bay 4 of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, the Ares I-X upper stage simulator service module/service adapter (left, center) has been installed on a stand. Other segments are placed and stacked on the floor around it. Ares I-X is the test vehicle for the Ares I, which is part of the Constellation Program to return men to the moon and beyond. The Ares I-X is targeted for launch in July 2009. Photo credit: NASA/Kim Shiflett

  5. KSC-2009-1396

    NASA Image and Video Library

    2009-01-28

    CAPE CANAVERAL, Fla. – Framework is being lifted from a transporter to be installed on the 16th floor for modifications in the Vehicle Assembly Building's high bay 3 at NASA's Kennedy Space Center in Florida related to the Ares I-X. The refurbishment of the facility is for the Constellation Program's Ares vehicles. The Ares I and Ares V rockets will be 325 feet and 360 feet tall, respectively, considerably taller than the space shuttle atop its mobile launcher platform. Photo credit: NASA/Troy Cryder

  6. Metastable mantle phase transformations and deep earthquakes in subducting oceanic lithosphere

    USGS Publications Warehouse

    Kirby, S.H.; Stein, S.; Okal, E.A.; Rubie, David C.

    1996-01-01

    Earth's deepest earthquakes occur as a population in subducting or previously subducted lithosphere at depths ranging from about 325 to 690 km. This depth interval closely brackets the mantle transition zone, characterized by rapid seismic velocity increases resulting from the transformation of upper mantle minerals to higher-pressure phases. Deep earthquakes thus provide the primary direct evidence for subduction of the lithosphere to these depths and allow us to investigate the deep thermal, thermodynamic, and mechanical ferment inside slabs. Numerical simulations of reaction rates show that the olivine ??? spinel transformation should be kinetically hindered in old, cold slabs descending into the transition zone. Thus wedge-shaped zones of metastable peridotite probably persist to depths of more than 600 km. Laboratory deformation experiments on some metastable minerals display a shear instability called transformational faulting. This instability involves sudden failure by localized superplasticity in thin shear zones where the metastable host mineral transforms to a denser, finer-grained phase. Hence in cold slabs, such faulting is expected for the polymorphic reactions in which olivine transforms to the spinel structure and clinoenstatite transforms to ilmenite. It is thus natural to hypothesize that deep earthquakes result from transformational faulting in metastable peridotite wedges within cold slabs. This consideration of the mineralogical states of slabs augments the traditional largely thermal view of slab processes and explains some previously enigmatic slab features. It explains why deep seismicity occurs only in the approximate depth range of the mantle transition zone, where minerals in downgoing slabs should transform to spinel and ilmenite structures. The onset of deep shocks at about 325 km is consistent with the onset of metastability near the equilibrium phase boundary in the slab. Even if a slab penetrates into the lower mantle, earthquakes should cease at depths near 700 km, because the seismogenic phase transformations in the slab are completed or can no longer occur. Substantial metastability is expected only in old, cold slabs, consistent with the observed restriction of deep earthquakes to those settings. Earthquakes should be restricted to the cold cores of slabs, as in any model in which the seismicity is temperature controlled, via the distribution of metastability. However, the geometries of recent large deep earthquakes pose a challenge for any such models. Transformational faulting may give insight into why deep shocks lack appreciable aftershocks and why their source characteristics, including focal mechanisms indicating localized shear failure rather than implosive deformation, are so similar to those of shallow earthquakes. Finally, metastable phase changes in slabs would produce an internal source of stress in addition to those due to the weight of the sinking slab. Such internal stresses may explain the occurrence of earthquakes in portions of lithosphere which have foundered to the bottom of the transition zone and/or are detached from subducting slabs. Metastability in downgoing slabs could have considerable geodynamic significance. Metastable wedges would reduce the negative buoyancy of slabs, decrease the driving force for subduction, and influence the state of stress in slabs. Heat released by metastable phase changes would raise temperatures within slabs and facilitate the transformation of spinel to the lower mantle mineral assemblage, causing slabs to equilibrate more rapidly with the ambient mantle and thus contribute to the cessation of deep seismicity. Because wedge formation should occur only for fast subducting slabs, it may act as a "parachute" and contribute to regulating plate speeds. Wedge formation would also have consequences for mantle evolution because the density of a slab stagnated near the bottom of the transition zone would increase as it heats up and the wedge tra

  7. Aseismic deep subduction of the Philippine Sea plate and slab window

    NASA Astrophysics Data System (ADS)

    Huang, Zhouchuan; Zhao, Dapeng; Hasegawa, Akira; Umino, Norihito; Park, Jung-Ho; Kang, Ik-Bum

    2013-10-01

    We have made great efforts to collect and combine a large number of high-quality data from local earthquakes and teleseismic events recorded by the dense seismic networks in both South Korea and West Japan. This is the first time that a large number of Korean and Japanese seismic data sets are analyzed jointly. As a result, a high-resolution 3-D P-wave velocity model down to 700-km depth is determined, which clearly shows that the Philippine Sea (PHS) plate has subducted aseismically down to ˜460 km depth under the Japan Sea, Tsushima Strait and East China Sea. The aseismic PHS slab is visible in two areas: one is under the Japan Sea off western Honshu, and the other is under East China Sea off western Kyushu. However, the aseismic PHS slab is not visible between the two areas, where a slab window has formed. The slab window is located beneath the center of the present study region where many teleseismic rays crisscross. Detailed synthetic tests were conducted, which indicate that both the aseismic PHS slab and the slab window are robust features. Using the teleseismic data recorded by the Japanese stations alone, the aseismic PHS slab and the slab window were also revealed (Zhao et al., 2012), though the ray paths in the Japanese data set crisscross less well offshore. The slab window may be caused by the subducted Kyushu-Palau Ridge and Kinan Seamount Chain where the PHS slab may be segmented. Hot mantle upwelling is revealed in the big mantle wedge above the Pacific slab under the present study region, which may have facilitated the formation of the PHS slab window. These novel findings may shed new light on the subduction history of the PHS plate and the dynamic evolution of the Japan subduction zone.

  8. Accelerated slab replacement using temporary precast panels and self-consolidating concrete : [summary].

    DOT National Transportation Integrated Search

    2016-06-01

    Researchers at Florida State University demonstrated the feasibility of using precast reinforced concrete panels to temporarily fill slab removal pits. The precast slabs can be driven on so traffic lanes can be open during the day, and new slab casti...

  9. Production of High Quality Die Steels from Large ESR Slab Ingots

    NASA Astrophysics Data System (ADS)

    Geng, Xin; Jiang, Zhou-hua; Li, Hua-bing; Liu, Fu-bin; Li, Xing

    With the rapid development of manufacture industry in China, die steels are in great need of large slab ingot of high quality and large tonnage, such as P20, WSM718R and so on. Solidification structure and size of large slab ingots produced with conventional methods are not satisfied. However, large slab ingots manufactured by ESR process have a good solidification structure and enough section size. In the present research, the new slab ESR process was used to produce the die steels large slab ingots with the maximum size of 980×2000×3200mm. The compact and sound ingot can be manufactured by the slab ESR process. The ultra-heavy plates with the maximum thickness of 410 mm can be obtained after rolling the 49 tons ingots. Due to reducing the cogging and forging process, the ESR for large slab ingots process can increase greatly the yield and production efficiency, and evidently cut off product costs.

  10. Age of the Subducting Philippine Sea Slab and Mechanism of Low-Frequency Earthquakes

    NASA Astrophysics Data System (ADS)

    Hua, Yuanyuan; Zhao, Dapeng; Xu, Yixian; Liu, Xin

    2018-03-01

    Nonvolcanic low-frequency earthquakes (LFEs) usually occur in young and warm subduction zones under condition of near-lithostatic pore fluid pressure. However, the relation between the LFEs and the subducting slab age has never been documented so far. Here we estimate the lithospheric age of the subducting Philippine Sea (PHS) slab beneath the Nankai arc by linking seismic tomography and a plate reconstruction model. Our results show that the LFEs in SW Japan take place in young parts ( 17-26 Myr) of the PHS slab. However, no LFE occurs beneath the Kii channel where the PHS slab is very young ( 15 Myr) and thin ( 29 km), forming an LFE gap there. According to the present results and previous works, we think that the LFE gap at the Kii channel is caused by joint effects of several factors, including the youngest slab age, high temperature, low fluid content, high permeability of the overlying plate, a slab tear, and hot upwelling flow below the PHS slab.

  11. Atlas of the underworld: Slab remnants in the mantle, their sinking history, and a new outlook on lower mantle viscosity

    NASA Astrophysics Data System (ADS)

    van der Meer, Douwe G.; van Hinsbergen, Douwe J. J.; Spakman, Wim

    2018-01-01

    Across the entire mantle we interpret 94 positive seismic wave-speed anomalies as subducted lithosphere and associate these slabs with their geological record. We document this as the Atlas of the Underworld, also accessible online at www.atlas-of-the-underworld.org, a compilation comprising subduction systems active in the past 300 Myr. Deeper slabs are correlated to older geological records, assuming no relative horizontal motions between adjacent slabs following break-off, using knowledge of global plate circuits, but without assuming a mantle reference frame. The longest actively subducting slabs identified reach the depth of 2500 km and some slabs have impinged on Large Low Shear Velocity Provinces in the deepest mantle. Anomously fast sinking of some slabs occurs in regions affected by long-term plume rising. We conclude that slab remnants eventually sink from the upper mantle to the core-mantle boundary. The range in subduction-age versus - depth in the lower mantle is largely inherited from the upper mantle history of subduction. We find a significant depth variation in average sinking speed of slabs. At the top of the lower mantle average slab sinking speeds are between 10 and 40 mm/yr, followed by a deceleration to 10-15 mm/yr down to depths around 1600-1700 km. In this interval, in situ time-stationary sinking rates suggest deceleration from 20 to 30 mm/yr to 4-8 mm/yr, increasing to 12-15 mm/yr below 2000 km. This corroborates the existence of a slab deceleration zone but we do not observe long-term (> 60 My) slab stagnation, excluding long-term stagnation due to compositional effects. Conversion of slab sinking profiles to viscosity profiles shows the general trend that mantle viscosity increases in the slab deceleration zone below which viscosity slowly decreases in the deep mantle. This is at variance with most published viscosity profiles that are derived from different observations, but agrees qualitatively with recent viscosity profiles suggested from material experiments.

  12. Tectonic affinities of the accreted basalts in southern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Yu; Yang, Huai-Jen; Liu, Yung-Hsin; Huang, Kuo-Fang; Takazawa, Eiichi

    2018-06-01

    Tectonic affinities of accreted basalts provide constraints on mass transport in convergent boundaries, improving our understandings on the evolution of regional geology. In this study, nineteen accreted basalts from the southernmost tip of Taiwan Island, which is on the convergent boundary between the Eurasian and Philippine Sea Plates, were analyzed for element concentrations as well as Sr, Nd, Hf, and Pb isotope ratios to investigate their tectonic affinities. All the samples contain > 3% LOI, reflecting post-magmatic alteration. LOI and Nb variation diagrams together with comparisons to oceanic basalt compositions indicated that the concentrations of most major elements and Rb, Sr, and Ba were modified by post-magmatic processes to varying extents, while P2O5, REE and HFSE remained immobile. Although some samples show Pb loss, most samples have Pb concentrations not affected by post-magmatic processes. Isotope ratios of Pb, Nd and Hf, generally reflect the mantle source characteristics. The εNd-εHf relationship and trace element abundance ratios indicated that the LREE-depleted samples were mostly scraped off the subducting South China Sea floor, reflecting the volumetric dominance of N-MORB on ocean floors. The overriding Philippine Sea Plate contributed both N-MORB and E-MORB to the accretionary prism. The tectonic affinities of the LREE-enriched samples, however, could not be unambiguously determined for the large geochemical variability of OIB from both subducting and overlying slabs. Based on our results, it is proposed that the tectonic affinity of the basalts in an accretionary prism can indicate the subduction polarity of the associated convergent boundary, providing a constraint for regional geology evolution.

  13. Assembly and remodeling of the fibrillar fibronectin extracellular matrix during gastrulation and neurulation in Xenopus laevis.

    PubMed

    Davidson, Lance A; Keller, Raymond; DeSimone, Douglas W

    2004-12-01

    Fibronectin, a major component of the extracellular matrix is critical for processes of cell traction and cell motility. Whole-mount confocal imaging of the three-dimensional architecture of the extracellular matrix is used to describe dynamic assembly and remodeling of fibronectin fibrils during gastrulation and neurulation in the early frog embryo. As previously reported, fibrils first appear under the prospective ectoderm. We describe here the first evidence for regulated assembly of fibrils along the somitic mesoderm/endoderm boundary as well as at the notochord/somitic mesoderm boundary and clearing of fibrils from the dorsal and ventral surfaces of the notochord that occurs over the course of a few hours. As gastrulation proceeds, fibrils are restored to the dorsal surface of the notochord, where the notochord contacts the prospective floor plate. As the neural folds form, fibrils are again remodeled as deep neural plate cells move medially. The process of neural tube closure leaves a region of the ectoderm overlying the neural crest transiently bare of fibrils. Fibrils are assembled surrounding the dorsal surface of the neural tube as the neural tube lumen is restored. Copyright (c) 2004 Wiley-Liss, Inc.

  14. The atomic arrangement of iimoriite-(Y), Y2(SiO4)(CO3)

    USGS Publications Warehouse

    Hughes, J.M.; Foord, E.E.; Jai-Nhuknan, J.; Bell, J.M.

    1996-01-01

    Iimoriite-(Y) from Bokan Mountain, Prince of Wales Island, Alaska has been studied using single-crystal X-ray-diffraction techniques. The mineral, ideally Y2(SiO4)(CO3), crystallizes in space group P1, with a 6.5495(13), b 6.6291(14), c 6.4395(11)A??, ?? 116.364(15), ?? 92.556(15) and ?? 95.506(17)??. The atomic arrangement has been solved and refined to an R value of 0.019. The arrangement of atoms consists of alternating (011) slabs of orthosilicate groups and carbonate groups, with no sharing of oxygen atoms between anionic complexes in adjacent slabs. Y1 atoms separate adjacent tetrahedra along [100] within the orthosilicate slab, and Y2 atoms separate adjacent carbonate groups along [100] within the carbonate slab. Adjacent orthosilicate and carbonate slabs are linked in (100) by bonding Y atoms from each slab to oxygen atoms of adjacent slabs, in the form of YO8 polyhedra. The Y1 atoms exist in Y12O14 dimers in the orthosilicate slab, and the Y2 atoms exist in continuous [011] ribbons of edge-sharing Y2O8 polyhedra in the carbonate slab.

  15. Limits on the critical length of damage in weak snowpack layers from en-echelon slab fracture spacing observed during avalanche release

    NASA Astrophysics Data System (ADS)

    Gauthier, D.; Hutchinson, D. J.

    2012-04-01

    We present simple estimates of the maximum possible critical length of damage or fracture in a weak snowpack layer required to maintain the propagation that leads to avalanche release, based on observations of 'en-echelon' slab fractures during avalanche release. These slab fractures may be preserved in situ if the slab does not slide down slope. The en-echelon fractures are spaced evenly, normally with one every one to ten metres or more. We consider a simple two-dimensional model of a slab and weak layer, with upslope fracture propagating the weak layer, and examine the relationship between the weak layer and en-echelon slab fractures. We assume that the slab fracture occurs in tension, and initiates at either the base or surface of the slab in the area of peak tensile stress at the tip of the weak layer fracture. We also assume that if at the time the slab is completely bisected by fracture the propagation in the weak layer will arrest spontaneously if it has not advanced beyond the critical length. In this scenario, en-echelon slab fractures may only form when the weak layer fracture repeatedly exceeds the critical length; otherwise, there could be only a single slab fracture. We estimate the position of the weak layer fracture at the time of slab bisection using the slab thickness and ratio between the fracture speeds in the weak layer and slab. We show that in the simple model en-echelon fractures only form if the slab thickness multiplied by the velocity ratio is greater than the critical length. Of course, the critical length must also be less than the en-echelon spacing. It follows that the first relationship must be valid independent of the occurrence of en-echelon fractures, although the speed ratio may be process-dependent and difficult to estimate. We use this method to calculate maximum critical lengths for propagation in actual avalanches with and without en echelon fractures, and discuss the implications for comparing competing propagation models. Furthermore, we discuss the possible applications to other cases of progressive basal failure and en-echelon fracturing, e.g. the ribbed flow bowls or so-called 'thumbprint' morphology which sometimes develops during landsliding in sensitive clay soils.

  16. Using Six Sigma methodology to reduce patient transfer times from floor to critical-care beds.

    PubMed

    Silich, Stephan J; Wetz, Robert V; Riebling, Nancy; Coleman, Christine; Khoueiry, Georges; Abi Rafeh, Nidal; Bagon, Emma; Szerszen, Anita

    2012-01-01

    In response to concerns regarding delays in transferring critically ill patients to intensive care units (ICU), a quality improvement project, using the Six Sigma process, was undertaken to correct issues leading to transfer delay. To test the efficacy of a Six Sigma intervention to reduce transfer time and establish a patient transfer process that would effectively enhance communication between hospital caregivers and improve the continuum of care for patients. The project was conducted at a 714-bed tertiary care hospital in Staten Island, New York. A Six Sigma multidisciplinary team was assembled to assess areas that needed improvement, manage the intervention, and analyze the results. The Six Sigma process identified eight key steps in the transfer of patients from general medical floors to critical care areas. Preintervention data and a root-cause analysis helped to establish the goal transfer-time limits of 3 h for any individual transfer and 90 min for the average of all transfers. The Six Sigma approach is a problem-solving methodology that resulted in almost a 60% reduction in patient transfer time from a general medical floor to a critical care area. The Six Sigma process is a feasible method for implementing healthcare related quality of care projects, especially those that are complex. © 2011 National Association for Healthcare Quality.

  17. A slab expression in the Gibraltar arc?

    NASA Astrophysics Data System (ADS)

    Nijholt, Nicolai; Govers, Rob; Wortel, Rinus

    2017-04-01

    The present-day geodynamic setting of the Gibraltar arc region results from several Myrs of subduction rollback in the overall (oblique) convergence of Africa and Iberia. As for most rollback settings in a convergence zone, the interaction of these two components is complex and distinctly non-stationary. Gibraltar slab rollback is considered to have stalled, or at least diminished largely in magnitude, since the late Miocene/early Pliocene, suggesting that the effect of the slab on present-day surface motions is negligible. However, GPS measurements indicate that the Gibraltar arc region has an anomalous motion with respect to both Iberia and Africa, i.e., the Gibraltar arc region does not move as part of the rigid Iberian, or the rigid African plate. A key question is whether this surface motion is an expression of the Gibraltar slab. Seismic activity in the Gibraltar region is diffuse and considerable in magnitude, making it a region of high seismic risk. Unlike the North African margin to the east, where thrust earthquakes dominate the focal mechanism tables, a complex pattern is observed with thrust, normal and strike-slip earthquakes in a region stretching between the northern Moroccan Atlas across the Gibraltar arc and Alboran Sea (with the Trans-Alboran Shear Zone) to the Betics of southern Spain. Even though no large mega-thrust earthquakes have been observed in recent history, slab rollback may not have completely ceased. However, since no activity has been observed in the accretionary wedge, probably since the Pliocene, it is likely that the subduction interface is locked. In this study, we perform a series of numerical models in which we combine the relative plate convergence, variable magnitude of friction on fault segments, regional variations in gravitational potential energy and slab pull of the Gibraltar slab. We seek to reproduce the GPS velocities and slip sense on regional faults and thereby determine whether the Gibraltar slab has an effect on surface motion. Slab shape and slab continuity to the surface, allowing slab pull to be transfered to the surface lithosphere, are key factors controlling the force balance in the region. We explore slab geometries with or without continuity at the Betics (with a slab window between the known subduction interface and a possible Betics connection) and/or continental material attached to the slab (which lowers the slab pull magnitude). Through our methodology, we are able to study which slab shape of those proposed in the literature best fits the surface data.

  18. Refining the Tonga Slab Geometry Using Slab Phases of Seismic Waves

    NASA Astrophysics Data System (ADS)

    Alongi, T.; Wei, S. S.; Blackman, D. K.

    2017-12-01

    Although the Tonga subducting slab geometry has been previously mapped by earthquake distribution, its detailed morphology is poorly constrained. The uncertainties of the slab surface relative to earthquakes can be translated into large errors in predicted temperature of hypocenters that is considered as a chief control of intermediate-depth seismicity. Seismic waves converted at the interface between the slab crust and the overlying mantle wedge can provide additional constraints on the location of the slab surface. A PS phase converted at the slab interface is observable in the horizontal components, whereas an SP converted phase can be seen in the vertical component. In this study, we analyze PS and SP phases in the seismic dataset of the 2009-2010 Ridge2000 Lau Spreading Center project, which consisted of 50 ocean bottom seismographs (OBSs) and 17 island-based seismic stations deployed in Fiji, Tonga, and the Lau Basin for about one year. More than 1,000 PS arrivals from local events were manually picked, predominantly with a 1-3 Hz filter. Next, the PS-P differential travel times will be inverted to determine improved depths of the slab surface relative to the local earthquakes and the receiving stations. The refined slab geometry will allow us to assess the thermal structure and dehydration reactions of the Tonga slab, lending further insight into the mechanisms of intermediate-depth seismicity.

  19. Elimination of deck joints using a corrosion resistant FRP approach

    NASA Astrophysics Data System (ADS)

    Aleti, Ashok Reddy

    The research presented herein describes the development of durable link slabs for jointless bridge decks based on using FRP grid for reinforcement. Specifically, the ductility of the FRP material was utilized to accommodate bridge deck deformations imposed by girder deflection, temperature variations, and concrete shrinkage. It would also provide a solution to a number of deterioration problems associated with bridge deck joints. The design concept of the link slabs was then examined to form the basis of design for FRP grid link slabs. Improved design of FRP grid link slab/concrete deck slab interface was confirmed in the numerical analysis. The mechanical properties between the FRP grid and concrete were evaluated. The behavior of the link slab was investigated and confirmed for durability. The results indicated that the technique would allow simultaneous achievement of structural need (lower flexural stiffness of the link slab approaching the behavior of a hinge) and durability need of the link slab. Also, the development length results confirm that the bond between the FRP grid and the concrete was highly improved. The overall investigation supports the contention that durable jointless concrete bridge decks may be designed and constructed with FRP grid link slabs. It is recommended that the link slab technique be used during new construction of the bridge decks and in repair and retrofit of the bridge decks.

  20. Seismicity and structure of Nazca Plate subduction zone in southern Peru

    NASA Astrophysics Data System (ADS)

    Lim, H.; Kim, Y.; Clayton, R. W.; Thurber, C. H.

    2016-12-01

    We define subducting plate geometries in the Nazca subduction zone by (re)locating intra-slab earthquakes in southern Peru (2-18°S) and taking previously published converted phase analysis results, to clarify the slab geometry and inferred relationships to the seismicity. We also provide both P- and S-wave velocities of the subducting Nazca Plate and mantle wedge portions close to the slab using double-difference tomography (Zhang and Thurber, 2003) to understand upper plate volcanism and subduction process. A total of 492 regional earthquakes from August 2008 to February 2013 recorded from the dense seismic array (PeruSE, 2013) are selected for the relocation and tomography. The relocated seismicity shows a smooth contortion in the slab-dip transition zone for 400 km between the shallow (25°)-to-flat dipping interface in the north and 40°-dipping interface in the south. We find a significant slab-dip difference (up to 10°) between our results and previously published slab models along the profile region sampling the normal-dip slab at depth (>100 km). Robust features in both P- and S-wave tomography inversions are dipping low-velocity slabs down to 100 km transitioning to higher-velocities at 100-140 km in both flat slab and dipping slab regions. Differences in the velocities of the mantle wedge between the two regions may indicate different hydration states in the wedge.

  1. Implications of slab mineralogy for subduction dynamics

    NASA Astrophysics Data System (ADS)

    Bina, Craig R.; Stein, Seth; Marton, Frederic C.; Van Ark, Emily M.

    2001-12-01

    Phase relations among mantle minerals are perturbed by the thermal environment of subducting slabs, both under equilibrium and disequilibrium (metastable) conditions. Such perturbations yield anomalies not only in seismic velocities but also in density. The buoyancy forces arising from these density anomalies may exert several important effects. They contribute to the stress field within the slab, in a fashion consistent with observed patterns of seismicity. They may affect subduction rates, both by inducing time-dependent velocity changes under equilibrium conditions and by imposing velocity limits through a thermal feedback loop under disequilibrium conditions. They may affect slab morphology, possibly inhibiting penetration of slabs into the lower mantle and allowing temporary stagnation of deflected or detached slabs. Latent heat release from phase transitions under disequilibrium conditions in slabs can yield isobaric superheating, which may generate adiabatic shear instabilities capable of triggering deep seismicity.

  2. Image transfer properties by photonic crystal slab with negative refractive index

    NASA Astrophysics Data System (ADS)

    Chen, Hongbo; Chen, Xiaoshuang; Zhou, Renlong; Lu, Wei

    2008-04-01

    We have studied the properties of image transferred by photonic crystal (PhC) slab with negative refractive index n=-1 and confirmed the negative refractive phonomenon, but not found the saturated image properties as expected. It is found that real images will not be formed when the source distance larger than the thickness of PhC, and the transferred images are virtual images. Furthermore, comparing the quality of images transferred by a PhC slab and a cascaded stack of photonic crystal slab (CSPS), we found that the transferred images are distorted in both situations. The image resolution is good along the direction parallel to the slab interface, but bad along the direction normal to the slab interface. Simulation results show that the image formed by a CSPS is no better than a PhC slab.

  3. Geometry of slab, intraslab stress field and its tectonic implication in the Nankai trough, Japan

    NASA Astrophysics Data System (ADS)

    Xu, J.; Kono, Y.

    2002-07-01

    The characteristics of geometry of slabs and the intraslab stress field in the Nankai subduction zone, Japan, were analyzed based on highly accurate hypocentral data and focal mechanism solutions. The results suggest that the shallow seismic zone of the Philippine Sea slab subducts with dip angels between 10 and 22 degrees beneath Shikoku and the Kii peninsula, and between 11 and 40 degrees beneath Kyushu. Two types of seismogenic stress field exist within the slab. The stress field of down-dip compression type can be seen in the slab beneath Shikoku and the Kii peninsula, where the horizontal component of regional compression stress is NNW. On the other hand the stress field of down-dip extension type within the slab is dominant in the region from western Shikoku to Kyushu, where the direction of horizontal compressive stress is near WWN. The existence of the two types of stress field is related to the differences of slab geometry and slab age of the subduciton zone. These properties imply that slab beneath Kyushu (40 Ma) probably is older than that beneath Shikoku and the Kii peninsula (11-20 Ma). The young slab of the oceanic Philippine Sea plate subducts with a shallow angle beneath the Eurasian plate in Shikoku and the Kii peninsula. The subduction has encountered strong resistance there, resulting in a down-dip compression stress field. The down-dip extension stress field may be related to the older slab of the Philippine Sea plate which subducts beneath Kyushu with a steeper dip angle.

  4. Water-induced convection in the Earth's mantle transition zone

    NASA Astrophysics Data System (ADS)

    Richard, Guillaume C.; Bercovici, David

    2009-01-01

    Water enters the Earth's mantle by subduction of oceanic lithosphere. Most of this water immediately returns to the atmosphere through arc volcanism, but a part of it is expected as deep as the mantle transition zone (410-660 km depth). There, slabs can be deflected and linger before sinking into the lower mantle. Because it lowers the density and viscosity of the transition zone minerals (i.e., wadsleyite and ringwoodite), water is likely to affect the dynamics of the transition zone mantle overlying stagnant slabs. The consequences of water exchange between a floating slab and the transition zone are investigated. In particular, we focus on the possible onset of small-scale convection despite the adverse thermal gradient (i.e., mantle is cooled from below by the slab). The competition between thermal and hydrous effects on the density and thus on the convective stability of the top layer of the slab is examined numerically, including water-dependent density and viscosity and temperature-dependent water solubility. For plausible initial water content in a slab (≥0.5 wt %), an episode of convection is likely to occur after a relatively short time delay (5-20 Ma) after the slab enters the transition zone. However, water induced rheological weakening is seen to be a controlling parameter for the onset time of convection. Moreover, small-scale convection above a stagnant slab greatly enhances the rate of slab dehydration. Small-scale convection also facilitates heating of the slab, which in itself may prolong the residence time of the slab in the transition zone.

  5. Slab stagnation and buckling in the mantle transition zone: Rheology, phase transition, trench migration, and seismic structure

    NASA Astrophysics Data System (ADS)

    Bina, Craig; Cizkova, Hana

    2014-05-01

    Subducting slabs may exhibit buckling instabilities and consequent folding behavior in the mantle transition zone for various combinations of dynamical parameters, accompanied by temporal variations in dip angle, plate velocity, and trench retreat. Parameters governing such behavior include both viscous forces (slab and mantle rheology) and buoyancy forces (slab thermal structure and mineral phase relations). 2D numerical experiments show that many parameter sets lead to slab deflection at the base of the transition zone, typically accompanied by quasi-periodic oscillations (consistent with previous scaling analyses) in largely anticorrelated plate and rollback velocities, resulting in undulating stagnant slabs as buckle folds accumulate subhorizontally atop the lower mantle. Slab interactions with mantle phase transitions are important components of this process (Bina and Kawakatsu, 2010; Čížková and Bina, 2013). For terrestrial parameter sets, trench retreat is found to be nearly ubiquitous, and trench advance is quite rare - due to both rheological structure and ridge-push effects (Čížková and Bina, 2013). Recent analyses of global plate motions indicate that significant trench advance is also rare on Earth, being largely restricted to the Izu-Bonin arc (Matthews et al., 2013). Consequently, we explore the conditions necessary for terrestrial trench advance through dynamical models involving the unusual geometry associated with the Philippine Sea region. Detailed images of buckled stagnant slabs are difficult to resolve due to smoothing effects inherent in seismic tomography, but velocity structures computed for compositionally layered slabs, using laboratory data on relevant mineral assemblages, can be spatially low-pass filtered for comparison with tomographic images of corresponding resolution. When applied to P-wave velocity anomalies from stagnant slab material beneath northeast China, model slabs which undulate due to compound buckling fit observations better than a flat-lying slab (Zhang et al., 2013). Earthquake hypocentral distributions and focal mechanisms may provide clearer insights into slab buckling, as they appear to vary systematically across regions of slab stagnation (Fukao and Obayashi, 2013). Stress fields computed from our dynamical models may help to illuminate such observations. References: Bina, C.R., and H. Kawakatsu, Buoyancy, bending, and seismic visibility in deep slab stagnation, Phys. Earth Planet. Inter., 183, 330-340, 2010. Čížková, H., and C.R. Bina, Effects of mantle and subduction-interface rheologies on slab stagnation and trench rollback, Earth Planet. Sci. Lett., 379, 95-103, 2013. Fukao, Y., and M. Obayashi, Deepest hypocentral distributions associated with stagnant slabs and penetrated slabs, Fall Meeting Abstracts, AGU, DI14A-01, 2013. Li, Z.-H., and N.M. Ribe, Dynamics of free subduction from 3-D boundary element modeling, J. Geophys. Res., 117, B06408. Matthews, D.C., L. Zheng, and R.G. Gordon, Do trenches advance? Fall Meeting Abstracts, AGU, T43D-2682, 2013. Zhang, Y., Y. Wang, Y. Wu, C. Bina, Z. Jin, and S. Dong, Phase transitions of harzburgite and buckled slab under eastern China, Geochem. Geophys. Geosys., 14, 1182-1199, 2013.

  6. Polymer impregnated bridge slabs : interim report, condition of slabs after three years of service life.

    DOT National Transportation Integrated Search

    1983-01-01

    The condition of six concrete bridge slabs that had been in service for three years was evaluated. The top 2 in. of the four slabs that had been impregnated to a depth of about 1 in. with a methyl methacrylate and trimethylolpropane trimethacrylate m...

  7. Nonimaging concentrators for diode-pumped slab lasers

    NASA Astrophysics Data System (ADS)

    Lacovara, Philip; Gleckman, Philip L.; Holman, Robert L.; Winston, Roland

    1991-10-01

    Diode-pumped slab lasers require concentrators for high-average power operation. We detail the properties of diode lasers and slab lasers which set the concentration requirements and the concentrator design methodologies that are used, and describe some concentrator designs used in high-average power slab lasers at Lincoln Laboratory.

  8. Field demonstration of new bridge approach slab designs and performance : [research project capsule].

    DOT National Transportation Integrated Search

    2008-10-01

    A normal bridge approach slab in Louisiana is a reinforced concrete slab. It connects : the bridge deck to the adjacent paved roadway. Its intended functions are: : 1. To span the void that may develop below the slab due to soil erosion or : embankme...

  9. Multizone Paper Platform for 3D Cell Cultures

    PubMed Central

    Derda, Ratmir; Hong, Estrella; Mwangi, Martin; Mammoto, Akiko; Ingber, Donald E.; Whitesides, George M.

    2011-01-01

    In vitro 3D culture is an important model for tissues in vivo. Cells in different locations of 3D tissues are physiologically different, because they are exposed to different concentrations of oxygen, nutrients, and signaling molecules, and to other environmental factors (temperature, mechanical stress, etc). The majority of high-throughput assays based on 3D cultures, however, can only detect the average behavior of cells in the whole 3D construct. Isolation of cells from specific regions of 3D cultures is possible, but relies on low-throughput techniques such as tissue sectioning and micromanipulation. Based on a procedure reported previously (“cells-in-gels-in-paper” or CiGiP), this paper describes a simple method for culture of arrays of thin planar sections of tissues, either alone or stacked to create more complex 3D tissue structures. This procedure starts with sheets of paper patterned with hydrophobic regions that form 96 hydrophilic zones. Serial spotting of cells suspended in extracellular matrix (ECM) gel onto the patterned paper creates an array of 200 micron-thick slabs of ECM gel (supported mechanically by cellulose fibers) containing cells. Stacking the sheets with zones aligned on top of one another assembles 96 3D multilayer constructs. De-stacking the layers of the 3D culture, by peeling apart the sheets of paper, “sections” all 96 cultures at once. It is, thus, simple to isolate 200-micron-thick cell-containing slabs from each 3D culture in the 96-zone array. Because the 3D cultures are assembled from multiple layers, the number of cells plated initially in each layer determines the spatial distribution of cells in the stacked 3D cultures. This capability made it possible to compare the growth of 3D tumor models of different spatial composition, and to examine the migration of cells in these structures. PMID:21573103

  10. Modular Flooring System

    NASA Technical Reports Server (NTRS)

    Thate, Robert

    2012-01-01

    The modular flooring system (MFS) was developed to provide a portable, modular, durable carpeting solution for NASA fs Robotics Alliance Project fs (RAP) outreach efforts. It was also designed to improve and replace a modular flooring system that was too heavy for safe use and transportation. The MFS was developed for use as the flooring for various robotics competitions that RAP utilizes to meet its mission goals. One of these competitions, the FIRST Robotics Competition (FRC), currently uses two massive rolls of broadloom carpet for the foundation of the arena in which the robots are contained during the competition. The area of the arena is approximately 30 by 72 ft (approximately 9 by 22 m). This carpet is very cumbersome and requires large-capacity vehicles, and handling equipment and personnel to transport and deploy. The broadloom carpet sustains severe abuse from the robots during a regular three-day competition, and as a result, the carpet is not used again for competition. Similarly, broadloom carpets used for trade shows at convention centers around the world are typically discarded after only one use. This innovation provides a green solution to this wasteful practice. Each of the flooring modules in the previous system weighed 44 lb (.20 kg). The improvements in the overall design of the system reduce the weight of each module by approximately 22 lb (.10 kg) (50 %), and utilize an improved "module-to-module" connection method that is superior to the previous system. The MFS comprises 4-by-4-ft (.1.2-by- 1.2-m) carpet module assemblies that utilize commercially available carpet tiles that are bonded to a lightweight substrate. The substrate surface opposite from the carpeted surface has a module-to-module connecting interface that allows for the modules to be connected, one to the other, as the modules are constructed. This connection is hidden underneath the modules, creating a smooth, co-planar flooring surface. The modules are stacked and strapped onto durable, commercially available drywall carts for storage and/or transportation. This method of storage and transportation makes it very convenient and safe when handling large quantities of modules.

  11. INTERIOR OVERVIEW OF CONTINUOUS CASTER WITH NO. 12 LADLE. MOLTEN ...

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

    INTERIOR OVERVIEW OF CONTINUOUS CASTER WITH NO. 12 LADLE. MOLTEN STEEL IS POURED FROM LADLE THROUGH SHROUD TO TUNDISH. FROM TUNDISH STEEL ENTERS MOLD THROUGH SHROUD AND FORMATION OF SLAB SHELL BEGINS. AS SLAB PROGRESSES THROUGH CONTAINMENT SECTION IT IS COOLED WITH AIR MIST SPRAYS AND CONTINUES SOLIDIFICATION. UPON EXITING THE MACHINE THE SLABS ARE CUT TO DESIRED LENGTH AND IDENTIFIED. THE SLABS ARE STACKED, REMOVED FROM MACHINE AND PREPARED FOR SHIPMENT TO HOT STRIP MILL. CASTER HAS ABILITY TO PRODUCE SINGLE OR TWIN CASTS. SINGLE SLABS PRODUCED MAY BE UP TO 102 INCHES; DOUBLE SLABS UP TO 49 INCHES. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  12. Flexural strength and behaviour of SFRSCC ribbed slab under four point bending

    NASA Astrophysics Data System (ADS)

    Ahmad, Hazrina; Hashim, Mohd Hisbany Mohd; Bakar, Afidah Abu; Hamzah, Siti Hawa; Rahman, Fadhillah Abdul

    2017-11-01

    An experimental investigation was carried out to study the ultimate strength and behaviour of SFRSCC ribbed slab under four point bending. Comparison was been made between ribbed slab that was fully reinforced with steel fibres (SFWS) with conventionally reinforced concrete ribbed slab (CS and CRC). The volume fraction of the 35 mm hooked end steel fibres used in the mix was 1% (80 kg/m3) with the aspect ratio of 65. Three full scale slab samples with the dimension of 2.8 x 1.2 m with 0.2 m thickness was constructed for the purpose of this study. The slab samples was loaded until failure in a four point bending test. As a whole, based on the results, it can be concluded that the performance of the steel fiber reinforced samples (SFWS) was found to be almost equivalent to the conventionally reinforced concrete ribbed slab sample (CRC).

  13. TESTING OF INDOOR RADON REDUCTION TECHNIQUES IN CENTRAL OHIO HOUSES: PHASE 2 (WINTER 1988-1989)

    EPA Science Inventory

    The report gives results of tests of developmental indoor radon reduction techniques in nine slab-on-grade and four crawl-space houses near Dayton. Ohio. he slab-on-grade tests indicated that, when there is a good layer of aggregate under the slab, the sub-slab ventilation (SSV) ...

  14. A review of the geodynamic evolution of flat slab subduction in Mexico, Peru, and Chile

    NASA Astrophysics Data System (ADS)

    Constantin Manea, Vlad; Manea, Marina; Ferrari, Luca; Orozco, María Teresa; Wong Valenzuela, Raul; Husker, Allen Leroy; Kostoglodovc, Vlad; Ionescu, Constantin

    2017-04-01

    Subducting plates around the globe display a large variability in terms of slab geometry, including regions where smooth and little variation in subduction parameters is observed. While the vast majority of subduction slabs plunge into the mantle at different, but positive dip angles, the end-member case of flat-slab subduction seems to strongly defy this rule and move horizontally several hundreds of kilometers before diving into the surrounding hotter mantle. By employing a comparative assessment for the Mexican, Peruvian and Chilean flat-slab subduction zones we find a series of parameters that apparently facilitate slab flattening. Among them, trench roll-back, as well as strong variations and discontinuities in the structure of oceanic and overriding plates seem to be the most important. However, we were not able to find the necessary and sufficient conditions that provide an explanation for the formation of flat slabs in all three subduction zones. In order to unravel the origin of flat-slab subduction, it is probably necessary a numerical approach that considers also the influence of surrounding plates, and their corresponding geometries, on 3D subduction dynamics.

  15. A review of the geodynamic evolution of flat slab subduction in Mexico, Peru, and Chile

    NASA Astrophysics Data System (ADS)

    Manea, V. C.; Manea, M.; Ferrari, L.; Orozco-Esquivel, T.; Valenzuela, R. W.; Husker, A.; Kostoglodov, V.

    2017-01-01

    Subducting plates around the globe display a large variability in terms of slab geometry, including regions where smooth and little variation in subduction parameters is observed. While the vast majority of subduction slabs plunge into the mantle at different, but positive dip angles, the end-member case of flat-slab subduction seems to strongly defy this rule and move horizontally several hundreds of kilometers before diving into the surrounding hotter mantle. By employing a comparative assessment for the Mexican, Peruvian and Chilean flat-slab subduction zones we find a series of parameters that apparently facilitate slab flattening. Among them, trench roll-back, as well as strong variations and discontinuities in the structure of oceanic and overriding plates seem to be the most important. However, we were not able to find the necessary and sufficient conditions that provide an explanation for the formation of flat slabs in all three subduction zones. In order to unravel the origin of flat-slab subduction, it is probably necessary a numerical approach that considers also the influence of surrounding plates, and their corresponding geometries, on 3D subduction dynamics.

  16. 3-D Transient Heat Transfer Analysis of Slab Heating Characteristics in a Reheating Furnace in Hot Strip Mills

    NASA Astrophysics Data System (ADS)

    Jang, J. Y.; Lee, Y. W.; Lin, C. N.; Wang, C. H.

    2016-05-01

    A three-dimensional mathematical transient heat transfer model for the prediction of temperature distribution within the slab has been developed by considering the thermal radiation in the walking-beam-type reheating furnace chamber. The steel slabs are heated up through the non-firing, preheating, 1st-heating, 2nd-heating, and soaking zones in the furnace, respectively, where the furnace wall temperature is function of time. Comparison with the in-situ experimental data from Steel Company in Taiwan shows that the present heat transfer model works well for the prediction of thermal behavior of the slab in the reheating furnace. The effects of different skid button height (H=60mm, 90mm, and 120mm) and different gap distance between two slabs (S=50mm, 75mm, and 100mm) on the slab skid mark formation and temperature profiles are investigated. It is found that the skid mark severity decreases with an increase in the skid button height. The effect of gap distance is important only for the slab edge planes, while it is insignificant for the slab central planes.

  17. Effect of kenaf fiber in reinforced concrete slab

    NASA Astrophysics Data System (ADS)

    Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.

    2018-04-01

    The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.

  18. Closure behavior of spherical void in slab during hot rolling process

    NASA Astrophysics Data System (ADS)

    Cheng, Rong; Zhang, Jiongming; Wang, Bo

    2018-04-01

    The mechanical properties of steels are heavily deteriorated by voids. The influence of voids on the product quality should be eliminated through rolling processes. The study on the void closure during hot rolling processes is necessary. In present work, the closure behavior of voids at the center of a slab at 800 °C during hot rolling processes has been simulated with a 3D finite element model. The shape of the void and the plastic strain distribution of the slab are obtained by this model. The void decreases along the slab thickness direction and spreads along the rolling direction but hardly changes along the strip width direction. The relationship between closure behavior of voids and the plastic strain at the center of the slab is analyzed. The effects of rolling reduction, slab thickness and roller diameter on the closure behavior of voids are discussed. The larger reduction, thinner slab and larger roller diameter all improve the closure of voids during hot rolling processes. Experimental results of the closure behavior of a void in the slab during hot rolling process mostly agree with the simulation results..

  19. Early Earth slab stagnation

    NASA Astrophysics Data System (ADS)

    Agrusta, R.; Van Hunen, J.

    2016-12-01

    At present day, the Earth's mantle exhibits a combination of stagnant and penetrating slabs within the transition zone, indicating a intermittent convection mode between layered and whole-mantle convection. Isoviscous thermal convection calculations show that in a hotter Earth, the natural mode of convection was dominated by double-layered convection, which may imply that slabs were more prone to stagnate in the transition zone. Today, slab penetration is to a large extent controlled by trench mobility for a plausible range of lower mantle viscosity and Clapeyron slope of the mantle phase transitions. Trench mobility is, in turn, governed by slab strength and density and upper plate forcing. In this study, we systematically investigate the slab-transition zone internation in the Early Earth, using 2D self-consistent numerical subduction models. Early Earth's higher mantle temperature facilitates decoupling between the plates and the underlying asthenosphere, and may result in slab sinking almost without trench retreat. Such behaviour together with a low resistance of a weak lower mantle may allow slabs to penetrate. The ability of slab to sink into the lower mantle throughout Earth's history may have important implications for Earth's evolution: it would provide efficient mass and heat flux through the transition zone therefore provide an efficient way to cool and mix the Earth's mantle.

  20. Degradation and mechanism of the mechanics and durability of reinforced concrete slab in a marine environment

    NASA Astrophysics Data System (ADS)

    Wu, Sheng-xing; Liu, Guan-guo; Bian, Han-bing; Lv, Wei-bo; Jiang, Jian-hua

    2016-04-01

    An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete (RC) slab at different ages in a marine environment. Results show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the slab. In the first stage, cracks appear. In the second stage, cracks develop from the edges to the middle of the slab. In the third stage, longitudinal and transverse corrosion-induced cracks coexist. The corrosion ratio of reinforcements nonlinearly increases with the age, and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is established. The flexural capacity of the corroded RC slab nonlinearly decreases with the age, and the model for the bearing capacity factor of the corroded RC slab is established. The mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ratio. Finally, the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design.

  1. Meteorological variables to aid forecasting deep slab avalanches on persistent weak layers

    USGS Publications Warehouse

    Marienthal, Alex; Hendrikx, Jordy; Birkeland, Karl; Irvine, Kathryn M.

    2015-01-01

    Deep slab avalanches are particularly challenging to forecast. These avalanches are difficult to trigger, yet when they release they tend to propagate far and can result in large and destructive avalanches. We utilized a 44-year record of avalanche control and meteorological data from Bridger Bowl ski area in southwest Montana to test the usefulness of meteorological variables for predicting seasons and days with deep slab avalanches. We defined deep slab avalanches as those that failed on persistent weak layers deeper than 0.9 m, and that occurred after February 1st. Previous studies often used meteorological variables from days prior to avalanches, but we also considered meteorological variables over the early months of the season. We used classification trees and random forests for our analyses. Our results showed seasons with either dry or wet deep slabs on persistent weak layers typically had less precipitation from November through January than seasons without deep slabs on persistent weak layers. Days with deep slab avalanches on persistent weak layers often had warmer minimum 24-hour air temperatures, and more precipitation over the prior seven days, than days without deep slabs on persistent weak layers. Days with deep wet slab avalanches on persistent weak layers were typically preceded by three days of above freezing air temperatures. Seasonal and daily meteorological variables were found useful to aid forecasting dry and wet deep slab avalanches on persistent weak layers, and should be used in combination with continuous observation of the snowpack and avalanche activity.

  2. Earthquakes and strain in subhorizontal slabs

    NASA Astrophysics Data System (ADS)

    Brudzinski, Michael R.; Chen, Wang-Ping

    2005-08-01

    Using an extensive database of fault plane solutions and precise locations of hypocenters, we show that the classic patterns of downdip extension (DDE) or downdip compression (DDC) in subduction zones deteriorate when the dip of the slab is less than about 20°. This result is depth-independent, demonstrated by both intermediate-focus (depths from 70 to 300 km) and deep-focus (depths greater than 300 km) earthquakes. The absence of pattern in seismic strain in subhorizontal slabs also occurs locally over scales of about 10 km, as evident from a detailed analysis of a large (Mw 7.1) earthquake sequence beneath Fiji. Following the paradigm that a uniform strain of DDE/DDC results from sinking of the cold, dense slab as it encounters resistance from the highly viscous mantle at depth, breakdown of DDE/DDC in subhorizontal slabs reflects waning negative buoyancy ("slab pull") in the downdip direction. Our results place a constraint on the magnitude of slab pull that is required to dominate over localized sources of stress and to align seismic strain release in dipping slabs. Under the condition of a vanishing slab pull, eliminating the only obvious source of regional stress, the abundance of earthquakes in subhorizontal slabs indicates that a locally variable source of stress is both necessary and sufficient to sustain the accumulation of elastic strain required to generate intermediate- and deep-focus seismicity. Evidence is growing that the process of seismogenesis under high pressures, including localized sources of stress, is tied to the presence of petrologic anomalies.

  3. Depth to the Juan De Fuca slab beneath the Cascadia subduction margin - a 3-D model for sorting earthquakes

    USGS Publications Warehouse

    McCrory, Patricia A.; Blair, J. Luke; Oppenheimer, David H.; Walter, Stephen R.

    2004-01-01

    We present an updated model of the Juan de Fuca slab beneath southern British Columbia, Washington, Oregon, and northern California, and use this model to separate earthquakes occurring above and below the slab surface. The model is based on depth contours previously published by Fluck and others (1997). Our model attempts to rectify a number of shortcomings in the original model and update it with new work. The most significant improvements include (1) a gridded slab surface in geo-referenced (ArcGIS) format, (2) continuation of the slab surface to its full northern and southern edges, (3) extension of the slab surface from 50-km depth down to 110-km beneath the Cascade arc volcanoes, and (4) revision of the slab shape based on new seismic-reflection and seismic-refraction studies. We have used this surface to sort earthquakes and present some general observations and interpretations of seismicity patterns revealed by our analysis. For example, deep earthquakes within the Juan de Fuca Plate beneath western Washington define a linear trend that may mark a tear within the subducting plate Also earthquakes associated with the northern stands of the San Andreas Fault abruptly terminate at the inferred southern boundary of the Juan de Fuca slab. In addition, we provide files of earthquakes above and below the slab surface and a 3-D animation or fly-through showing a shaded-relief map with plate boundaries, the slab surface, and hypocenters for use as a visualization tool.

  4. Unusually deep Bonin earthquake of 30 May 2015: A precursory signal to slab penetration?

    NASA Astrophysics Data System (ADS)

    Obayashi, Masayuki; Fukao, Yoshio; Yoshimitsu, Junko

    2017-02-01

    An M7.9 earthquake occurred on 30 May 2015 at an unusual depth of 680 km downward and away from the well-defined Wadati-Benioff (WB) zone of the southern Bonin arc. To the north (northern Bonin), the subducted slab is stagnant above the upper-lower mantle boundary at 660-km depth, where the WB zone bends forward to sub-horizontal. To the south (northern Mariana), it penetrates the boundary, where the WB zone extends near-vertically down to the boundary. Thus, the southern Bonin slab can be regarded as being in a transitional state from slab stagnation to penetration. The transition is shown to happen rapidly within the northern half of the southern Bonin slab where the heel part of the shoe-like configured stagnant slab hits the significantly depressed 660-km discontinuity. The mainshock and aftershocks took place in this heel part where they are sub-vertically aligned in approximate parallel to their maximum compressional axes. Here, the dips of the compressional axes of WB zone earthquakes change rapidly across the thickness of the slab from the eastern to western side and along the strike of the slab from the northern to southern side, suggesting rapid switching of the downdip compression axis in the shoe-shaped slab. Elastic deformation associated with the WB zone seismicity is calculated by viewing it as an integral part of the slab deformation process. With this deformation, the heel part is deepened relative to the arch part and is compressed sub-vertically and stretched sub-horizontally, a tendency consistent with the idea of progressive decent of the heel part in which near-vertical compressional stress is progressively accumulated to generate isolated shocks like the 2015 event and eventually to initiate slab penetration.

  5. Slab stagnation and detachment under northeast China

    NASA Astrophysics Data System (ADS)

    Honda, Satoru

    2016-03-01

    Results of tomography models around the Japanese Islands show the existence of a gap between the horizontally lying (stagnant) slab extending under northeastern China and the fast seismic velocity anomaly in the lower mantle. A simple conversion from the fast velocity anomaly to the low-temperature anomaly shows a similar feature. This feature appears to be inconsistent with the results of numerical simulations on the interaction between the slab and phase transitions with temperature-dependent viscosity. Such numerical models predict a continuous slab throughout the mantle. I extend previous analyses of the tomography model and model calculations to infer the origins of the gap beneath northeastern China. Results of numerical simulations that take the geologic history of the subduction zone into account suggest two possible origins for the gap: (1) the opening of the Japan Sea led to a breaking off of the otherwise continuous subducting slab, or (2) the western edge of the stagnant slab is the previous subducted ridge, which was the plate boundary between the extinct Izanagi and the Pacific plates. Origin (2) suggesting the present horizontally lying slab has accumulated since the ridge subduction, is preferable for explaining the present length of the horizontally lying slab in the upper mantle. Numerical models of origin (1) predict a stagnant slab in the upper mantle that is too short, and a narrow or non-existent gap. Preferred models require rather stronger flow resistance of the 660-km phase change than expected from current estimates of the phase transition property. Future detailed estimates of the amount of the subducted Izanagi plate and the present stagnant slab would be useful to constrain models. A systematic along-arc variation of the slab morphology from the northeast Japan to Kurile arcs is also recognized, and its understanding may constrain the 3D mantle flow there.

  6. The 2017 Mw = 8.2 Tehuantepec earthquake: a slab bending or slab pull rupture?

    NASA Astrophysics Data System (ADS)

    Duputel, Z.; Gombert, B.; Simons, M.; Fielding, E. J.; Rivera, L. A.; Bekaert, D. P.; Jiang, J.; Liang, C.; Moore, A. W.; Liu, Z.

    2017-12-01

    On September 8th 2017, a regionally destructive Mw 8.2 intra-slab earthquake struck Mexico in the Gulf of Tehuantepec. While large intermediate depth intra-slab earthquakes are a major hazard, we have only a limited knowledge of the strain budgets within subducting slabs. Several mechanisms have been proposed to explain intraplate earthquakes in subduction zones. Bending stresses might cause the occurrence of seismic events located at depths where the slab dip changes abruptly. However, an alternative explanation is needed if the ruptures are found to propagate through the entire lithosphere. Depending on the coupling of the subduction interface, intraplate earthquakes occurring updip or downdip of the locked zone could also be caused by the negative buoyancy of the sinking slab (i.e., slab pull). The increasing availability of near-fault data provides a unique opportunity to better constrain the seismogenic behavior of large intra-slab earthquakes. Teleseismic analyses of the 2017 Tehuantepec earthquake lead to contrasting statements about the depth extent of the rupture: while most of long period centroid moment tensor inversions yield fairly large centroid depths (>40 km), some finite-fault models suggest much shallower slip concentrated at depths less than 30 km. In this study, we analyze GPS, InSAR, tsunami and seismological data to constrain the earthquake location, fault geometry and slip distribution. We use a Bayesian approach devoid of significant spatial smoothing to characterize the range of allowable rupture depths. In addition, to cope with potential artifacts in centroid depth estimates due to unmodeled lateral heterogeneities, we also analyze long-period seismological data using a full 3D Earth model. Preliminary results suggest a fairly deep rupture consistent with a slab-pull process breaking a significant proportion of the lithosphere and potentially reflecting at least local detachment of the slab.

  7. Untangling Slab Dynamics Using 3-D Numerical and Analytical Models

    NASA Astrophysics Data System (ADS)

    Holt, A. F.; Royden, L.; Becker, T. W.

    2016-12-01

    Increasingly sophisticated numerical models have enabled us to make significant strides in identifying the key controls on how subducting slabs deform. For example, 3-D models have demonstrated that subducting plate width, and the related strength of toroidal flow around the plate edge, exerts a strong control on both the curvature and the rate of migration of the trench. However, the results of numerical subduction models can be difficult to interpret, and many first order dynamics issues remain at least partially unresolved. Such issues include the dominant controls on trench migration, the interdependence of asthenospheric pressure and slab dynamics, and how nearby slabs influence each other's dynamics. We augment 3-D, dynamically evolving finite element models with simple, analytical force-balance models to distill the physics associated with subduction into more manageable parts. We demonstrate that for single, isolated subducting slabs much of the complexity of our fully numerical models can be encapsulated by simple analytical expressions. Rates of subduction and slab dip correlate strongly with the asthenospheric pressure difference across the subducting slab. For double subduction, an additional slab gives rise to more complex mantle pressure and flow fields, and significantly extends the range of plate kinematics (e.g., convergence rate, trench migration rate) beyond those present in single slab models. Despite these additional complexities, we show that much of the dynamics of such multi-slab systems can be understood using the physics illuminated by our single slab study, and that a force-balance method can be used to relate intra-plate stress to viscous pressure in the asthenosphere and coupling forces at plate boundaries. This method has promise for rapid modeling of large systems of subduction zones on a global scale.

  8. Equilibrium properties of simple metal thin films in the self-compressed stabilized jellium model.

    PubMed

    Mahmoodi, T; Payami, M

    2009-07-01

    In this work, we have applied the self-compressed stabilized jellium model to predict the equilibrium properties of isolated thin Al, Na and Cs slabs. To make a direct correspondence to atomic slabs, we have considered only those L values that correspond to n-layered atomic slabs with 2≤n≤20, for surface indices (100), (110), and (111). The calculations are based on the density functional theory and self-consistent solution of the Kohn-Sham equations in the local density approximation. Our results show that firstly, the quantum size effects are significant for slabs with sizes smaller than or near to the Fermi wavelength of the valence electrons λ(F), and secondly, some slabs expand while others contract with respect to the bulk spacings. Based on the results, we propose a criterion for realization of significant quantum size effects that lead to expansion of some thin slabs. For more justification of the criterion, we have tested it on Li slabs for 2≤n≤6. We have compared our Al results with those obtained from using all-electron or pseudo-potential first-principles calculations. This comparison shows excellent agreements for Al(100) work functions, and qualitatively good agreements for the other work functions and surface energies. These agreements justify the way we have used the self-compressed stabilized jellium model for the correct description of the properties of simple metal slab systems. On the other hand, our results for the work functions and surface energies of large- n slabs are in good agreement with those obtained from applying the stabilized jellium model for semi-infinite systems. In addition, we have performed the slab calculations in the presence of surface corrugation for selected Al slabs and have shown that the results are worsened.

  9. Seismicity and structure of Nazca Plate subduction zone in southern Peru

    NASA Astrophysics Data System (ADS)

    Lim, H.; Kim, Y.; Clayton, R. W.

    2015-12-01

    We image the Nazca plate subduction zone system by detecting and (re)locating intra-slab earthquakes in southern Peru. Dense seismic arrays (PeruSE, 2013) were deployed along four lines to target geophysical characterization of the subduction system in the transition zone between flat and normal dipping segments of the Nazca plate (2-15°S). The arc volcanism is absent near the flat slab segment, and currently, the correlation between the location of the active volcanic front and corresponding slab depth is neither clear nor consistent between previously published models from seismicity. We detect 620 local earthquakes from August 2008 to February 2013 by manually picking 6559 and 4145 arrival times for P- and S-phases, respectively. We observe that the S-phase data is helpful to reduce the trade-off between origin time and depth of deeper earthquakes (>100 km). Earthquake locations are relocated to constrain the Nazca slab-mantle interface in the slab-dip transition zone using 7322 measurements of differential times of nearby earthquake pairs by waveform cross-correlation. We also employ the double-difference tomography (Zhang and Thurber, 2003) to further improve earthquake source locations and the spatial resolution of the velocity structure simultaneously. The relocated hypocenters clearly delineate the dipping Wadati-Benioff zone in the slab-dip transition zone between the shallow- (25°) to-flat dipping slab segment in the north and the normal (40°) dipping segment in the south. The intermediate-depth seismicity in the flat slab region stops at a depth of ~100 km and a horizontal distance of ~400 km from the trench. We find a significant slab-dip difference (up to 10°) between our relocated seismicity and previously published slab models along the profile region sampling the normal-dip slab at depth (>100 km).

  10. Upper mantle anisotropy beneath Peru from SKS splitting: Constraints on flat slab dynamics and interaction with the Nazca Ridge

    NASA Astrophysics Data System (ADS)

    Eakin, Caroline M.; Long, Maureen D.; Wagner, Lara S.; Beck, Susan L.; Tavera, Hernando

    2015-02-01

    The Peruvian flat slab is by far the largest region of flat subduction in the world today, but aspects of its structure and dynamics remain poorly understood. In particular, questions remain over whether the relatively narrow Nazca Ridge subducting beneath southern Peru provides dynamic support for the flat slab or it is just a passive feature. We investigate the dynamics and interaction of the Nazca Ridge and the flat slab system by studying upper mantle seismic anisotropy across southern Peru. We analyze shear wave splitting of SKS, sSKS, and PKS phases at 49 stations distributed across the area, primarily from the PerU Lithosphere and Slab Experiment (PULSE). We observe distinct spatial variations in anisotropic structure along strike, most notably a sharp transition from coherent splitting in the north to pervasive null (non-split) arrivals in the south, with the transition coinciding with the northern limit of the Nazca Ridge. For both anisotropic domains there is evidence for complex and multi-layered anisotropy. To the north of the ridge our *KS splitting measurements likely reflect trench-normal mantle flow beneath the flat slab. This signal is then modified by shallower anisotropic layers, most likely in the supra-slab mantle, but also potentially from within the slab. To the south the sub-slab mantle is similarly anisotropic, with a trench-oblique fast direction, but widespread nulls appear to reflect dramatic heterogeneity in anisotropic structure above the flat slab. Overall the regional anisotropic structure, and thus the pattern of deformation, appears to be closely tied to the location of the Nazca Ridge, which further suggests that the ridge plays a key role in the mantle dynamics of the Peruvian flat slab system.

  11. Slab anisotropy from subduction zone guided waves in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, K. H.; Tseng, Y. L.; Hu, J. C.

    2014-12-01

    Frozen-in anisotropic structure in the oceanic lithosphere and faulting/hydration in the upper layer of the slab are expected to play an important role in anisotropic signature of the subducted slab. Over the past several decades, despite the advances in characterizing anisotropy using shear wave splitting method and its developments, the character of slab anisotropy remains poorly understood. In this study we investigate the slab anisotropy using subduction zone guided waves characterized by long path length in the slab. In the southernmost Ryukyu subduction zone, seismic waves from events deeper than 100 km offshore northern Taiwan reveal wave guide behavior: (1) a low-frequency (< 1 Hz) first arrival recognized on vertical and radial components but not transverse component (2) large, sustained high-frequency (3-10 Hz) signal in P and S wave trains. The depth dependent high-frequency content (3-10Hz) confirms the association with a waveguide effect in the subducting slab rather than localized site amplification effects. Using the selected subduction zone guided wave events, we further analyzed the shear wave splitting for intermediate-depth earthquakes in different frequency bands, to provide the statistically meaningful shear wave splitting parameters. We determine shear wave splitting parameters from the 34 PSP guided events that are deeper than 100 km with ray path traveling along the subducted slab. From shear wave splitting analysis, the slab and crust effects reveal consistent polarization pattern of fast directions of EN-WS and delay time of 0.13 - 0.27 sec. This implies that slab anisotropy is stronger than the crust effect (<0.1 s) but weaker than the mantle wedge and sub-slab mantle effect (0.3-1.3 s) in Taiwan.

  12. Mantle flow influence on subduction evolution

    NASA Astrophysics Data System (ADS)

    Chertova, Maria V.; Spakman, Wim; Steinberger, Bernhard

    2018-05-01

    The impact of remotely forced mantle flow on regional subduction evolution is largely unexplored. Here we investigate this by means of 3D thermo-mechanical numerical modeling using a regional modeling domain. We start with simplified models consisting of a 600 km (or 1400 km) wide subducting plate surrounded by other plates. Mantle inflow of ∼3 cm/yr is prescribed during 25 Myr of slab evolution on a subset of the domain boundaries while the other side boundaries are open. Our experiments show that the influence of imposed mantle flow on subduction evolution is the least for trench-perpendicular mantle inflow from either the back or front of the slab leading to 10-50 km changes in slab morphology and trench position while no strong slab dip changes were observed, as compared to a reference model with no imposed mantle inflow. In experiments with trench-oblique mantle inflow we notice larger effects of slab bending and slab translation of the order of 100-200 km. Lastly, we investigate how subduction in the western Mediterranean region is influenced by remotely excited mantle flow that is computed by back-advection of a temperature and density model scaled from a global seismic tomography model. After 35 Myr of subduction evolution we find 10-50 km changes in slab position and slab morphology and a slight change in overall slab tilt. Our study shows that remotely forced mantle flow leads to secondary effects on slab evolution as compared to slab buoyancy and plate motion. Still these secondary effects occur on scales, 10-50 km, typical for the large-scale deformation of the overlying crust and thus may still be of large importance for understanding geological evolution.

  13. The upper crust laid on its side: tectonic implications of steeply tilted crustal slabs for extension in the basin and range

    USGS Publications Warehouse

    Howard, Keith A.

    2005-01-01

    Tilted slabs expose as much as the top 8–15 km of the upper crust in many parts of the Basin and Range province. Exposures of now-recumbent crustal sections in these slabs allow analysis of pre-tilt depth variations in dike swarms, plutons, and thermal history. Before tilting the slabs were panels between moderately dipping, active Tertiary normal faults. The slabs and their bounding normal faults were tilted to piggyback positions on deeper footwalls that warped up isostatically beneath them during tectonic unloading. Stratal dips within the slabs are commonly tilted to vertical or even slightly overturned, especially in the southern Basin and Range where the thin stratified cover overlies similarly tilted basement granite and gneiss. Some homoclinal recumbent slabs of basement rock display faults that splay upward into forced folds in overlying cover sequences, which thereby exhibit shallower dips. The 15-km maximum exposed paleodepth for the slabs represents the base of the brittle upper crust, as it coincides with the depth of the modern base of the seismogenic zone and the maximum focal depths of large normal-fault earthquakes in the Basin and Range. Many upended slabs accompany metamorphic core complexes, but not all core complexes have corresponding thick recumbent hanging-wall slabs. The Ruby Mountains core complex, for example, preserves only scraps of upper-plate rocks as domed-up extensional klippen, and most of the thick crustal section that originally overlay the uplifted metamorphic core now must reside below little-tilted hanging-wall blocks in the Elko-Carlin area to the west. The Whipple and Catalina Mountains core complexes in contrast are footwall to large recumbent hanging-wall slabs of basement rock exposing 8-15 km paleodepths that originally roofed the metamorphic cores; the exposed paleodepths require that a footwall rolled up beneath the slabs.

  14. Focusing Fluids towards the Arc: the Role of Rehydration Reactions and Rheology

    NASA Astrophysics Data System (ADS)

    Wilson, C. R.; Spiegelman, M. W.; Van Keken, P. E.; Hacker, B. R.

    2015-12-01

    Aqueous fluids released from the down-going slab in subduction zones are generally thought to be the cause of arc volcanism. However there is a significant discrepancy between the consistent location of the volcanic front with respect to intermediate depth earthquakes (e.g. 100+/-40 km; England et al., GJI, 2004, Syracuse & Abers, G-cubed, 2006) and the large depth range over which dehydration reactions are predicted to occur in the slab (e.g. 80-250 km; van Keken et al., JGR, 2011).By coupling the fluid flow to the solid rheology through compaction pressure, recent numerical models (Wilson et al., EPSL, 2014) demonstrated a number of focusing mechanisms that can be invoked to explain this apparent discrepancy. Most notable among these were permeability channels within the slab. These were shown to be highly effective in transporting fluid from deeper fluid sources along the slab towards the shallowest source. In the presence of these channels the majority of the fluid is released into the mantle wedge far shallower and closer to the arc than it was originally generated.While observations consistent with free fluids in the slab have been reported (e.g. Shiina et al., GRL, 2013), it is possible that changing the reactivity and rheology of the slab can change the efficiency of in-slab transport (e.g. Wada et al., EPSL, 2012, Faccenda et al., G3, 2012). We present a series of simplified model problems of fluid flow within the slab and mantle wedge demonstrating the potential effect of these processes on fluid flux. In particular, pseudo-1D models show that if fluids can efficiently rehydrate slab minerals, then these reactions can shut down fluid pathways within the slab, resulting in deeper release of fluid into the mantle wedge. We will expand these results to consider the effects of rehydration in 2-D calculations. In addition, our previous models have considered only the simplest rheologies and geometries for the slab. We will also discuss new results that investigate simple visco-plastic models for the slab that limit the stresses and maximum viscosities in the slab for more realistic slab geometries. Despite these additional complexities, the robust observation of the location of the volcanic front with respect to intermediate depth earthquakes provides a clear test for evaluating subduction zone models.

  15. Numerical modeling of Farallon Plate flat-slab subduction: Influence of lithosphere structure and rheology on slab dynamics

    NASA Astrophysics Data System (ADS)

    Liu, X.; Currie, C. A.

    2017-12-01

    The subducted Farallon plate is believed to have evolved to a flat geometry underneath North America plate during Late Cretaceous, triggering Laramide deformation within the continental interior. However, the mechanism that caused the oceanic slab to flatten and the factors that control the flat-slab depth remain uncertain. In this work, we use 2D thermal-mechanical models using the SOPALE code to study the subduction dynamics from 90 Ma to 50 Ma. During this period, an oceanic plateau (Shatsky Conjugate) is inferred to have subducted beneath western North America and interacted with the continental lithosphere, including areas of thicker lithosphere such as the Colorado Plateau and Wyoming Craton. Based on seismic tomography and plate reconstruction data sets, we built a set of models to examine the influence of the structure and rheology of the oceanic and continental plates on slab dynamics. Models include a 600 km wide oceanic plateau consisting of 18 km thick crust and a 36 km thick underlying harzburgite layer, and we ran a series of model experiments to test different continental thicknesses (80 km, 120 km, & 180 km) and continental mantle lithosphere strengths (approximating conditions from wet olivine to dry olivine). Consistent with earlier studies, we find that creation of a long flat slab requires a buoyant oceanic plateau (i.e., non-eclogitized crust) and trenchward motion of the continent. In addition, our models demonstrate the upper plate has an important control on slab dynamics. A flat slab requires either a thin continent or, if the continent is thick, its mantle lithosphere must be relatively weak so that it can be displaced by the flattening slab. The depth of the flat slab is mainly controlled by two factors: (1) the continental thickness and (2) the strength of the continental mantle lithosphere. For the same initial lithosphere thickness (120 km), a shallower flat slab ( 90 km depth) occurs for the weakest mantle lithosphere ( wet olivine) compared to 120 km depth for strong ( dry) mantle lithosphere because the flat slab removes the lowermost weak lithosphere. Moreover, an even deeper slab ( 130 km) can be found underneath the weakest but thicker continental lithosphere (180 km). Future models will focus on how the flat slab may induce hydration and deformation for the overriding continental plate.

  16. SMART Structures User's Guide - Version 3.0

    NASA Technical Reports Server (NTRS)

    Spangler, Jan L.

    1996-01-01

    Version 3.0 of the Solid Modeling Aerospace Research Tool (SMART Structures) is used to generate structural models for conceptual and preliminary-level aerospace designs. Features include the generation of structural elements for wings and fuselages, the integration of wing and fuselage structural assemblies, and the integration of fuselage and tail structural assemblies. The highly interactive nature of this software allows the structural engineer to move quickly from a geometry that defines a vehicle's external shape to one that has both external components and internal components which may include ribs, spars, longerons, variable depth ringframes, a floor, a keel, and fuel tanks. The geometry that is output is consistent with FEA requirements and includes integrated wing and empennage carry-through and frame attachments. This report provides a comprehensive description of SMART Structures and how to use it.

  17. The effects of subduction termination on the continental lithosphere: Linking volcanism, deformation, surface uplift, and slab tearing in central Anatolia

    NASA Astrophysics Data System (ADS)

    Delph, Jonathan R.; Abgarmi, Bijan; Ward, Kevin M.; Beck, Susan L.; Arda Ozacar, A.; Zandt, George; Sandvol, Eric; Turkelli, Niyazi; Kalafat, Dogan

    2017-04-01

    The lithospheric evolution of Anatolia is largely defined by processes associated with the terminal stages of subduction along its southern margin. Central Anatolia represents the transition from the subduction of oceanic lithosphere at the Aegean trench in the west to the Arabian - Eurasian continental collision in the east. In the overriding plate, this complicated transition is contemporaneous with uplift along the southern margin of central Anatolia (2 km in 6 Myr), voluminous felsic-intermediate ignimbrite eruptions (>1000 km3), extension, and tectonic deformation reflected by abundant low-magnitude seismic activity. The addition of 72 seismic stations as part of the Continental Dynamics - Central Anatolian Tectonics project, along with development of a new approach to the joint inversion of receiver functions and dispersion data, enables us obtain a high-resolution 3D shear wave velocity model of central Anatolia down to 150 km. This new velocity model has important implications for the complex interactions between the downgoing, segmenting African lithosphere and the overriding Anatolian Plate. These results reveal that the lithosphere of central Anatolia and the northern Arabian Plate is thin (<50 to 80 km). The Central Taurus Mountains, which have experienced 2 km of uplift in the past 6 Ma, are underlain by the fastest shear velocities in the region (>4.5 km/s), indicating the presence of the Cyprean slab beneath central Anatolia. Thus, uplift of the Central Taurus Mountains may be due to slab rebound after the detachment of the oceanic portion of the Cyprean slab beneath Anatolia rather than the presence of shallow asthenospheric material. These fast velocities extend to the northern margin of the Central Taurus Mountains, giving way to a NE-SW trend of very slow upper mantle shear wave velocities (<4.2 km/s) beneath the Central Anatolian Volcanic Province. These slow velocities are interpreted to be shallow, warm asthenosphere in which melt is present. The combination of a shallow asthenosphere and lithospheric-scale weaknesses associated with relict tectonic structures formed during the assembly of Anatolia are responsible for the spatial distribution of volcanism in the Central Anatolian Volcanic Province. Finally, we present a model for the evolution of central Anatolia that brings together the volcanism, extension in the Kirsehir Block, uplift of the southern margin of central Anatolia, and our seismic images.

  18. Vertical slab sinking and westward subduction offshore of Mesozoic North America

    NASA Astrophysics Data System (ADS)

    Sigloch, Karin; Mihalynuk, Mitchell G.

    2013-04-01

    Subducted slabs in the mantle, as imaged by seismic tomography, preserve a record of ancient subduction zones. Ongoing debate concerns how direct this link is. How long ago did each parcel of slab subduct, and where was the trench located relative to the imaged slab position? Resolving these questions will benefit paleogeographic reconstructions, and restrict the range of plausible rheologies for mantle convection simulations. We investigate one of the largest and best-constrained Mesozoic slab complexes, the "Farallon" in the transition zone and lower mantle beneath North America. We quantitatively integrate observations from whole-mantle P-wave tomography, global plate reconstructions, and land geological evidence from the North American Cordillera. These three data sets permit us to test the simplest conceivable hypothesis for linking slabs to paleo-trenches: that each parcel of slab sank only vertically shortly after entering the trench That is, we test whether within the limits of tomographic resolution, all slab material lies directly below the location where it subducted beneath its corresponding arc. Crucially and in contrast to previous studies, we do not accept or impose an Andean-style west coast trench (Farallon-beneath-continent subduction) since Jurassic times, as this scenario is inconsistent with many geological observations. Slab geometry alone suggests that trenches started out as intra-oceanic because tomography images massive, linear slab "walls" in the lower mantle, extending almost vertically from about 800 km to 2000+ km depth. Such steep geometries would be expected from slabs sinking vertically beneath trenches that were quasi-stationary over many tens of millions of years. Intra-oceanic trenches west of Mesozoic North America could have been stationary, whereas a coastal Farallon trench could not, because the continent moved westward continuously as the Atlantic opened. Overlap of North American west-coast positions, as reconstructed in a hotspot reference frame, with elongate slab walls predicts where and when the intra-oceanic trenches would have been overridden by the westward-moving continent. Land geology plays the role of a validating data set: trench override is predicted to coincide with accretion of buoyant arc terranes, deformation of the continental margin and slab window volcanism. We find excellent agreement between predicted and observed accretion episodes, validating both vertical sinking (within observational uncertainties of a few hundred kilometers laterally), and westward subduction beneath an archipelago of island arcs west of Jura-Cretaceous North America. Amalgamation of the arcs with North America occurred as the intervening ocean crust was consumed. Implied slab sinking rates are of 10±2 mm/a, uniformly for three different slab walls. We conclude that the hypothesis of essentially vertical slab sinking produces a self-consistent model that explains first-order observations of 200 Ma - 50 Ma Cordilleran geology. By contrast, the standard scenario of a continental Farallon trench requires massive amounts of slab to be laterally displaced by 1000+ km after subduction, and offers no explanation for a long series of Cretaceous terrane accretions.

  19. Recurrent isolation of hydrogen peroxide-resistant spores of Bacillus pumilus from a spacecraft assembly facility

    NASA Technical Reports Server (NTRS)

    Kempf, Michael J.; Chen, Fei; Kern, Roger; Venkateswaran, Kasthuri

    2005-01-01

    While the microbial diversity of a spacecraft assembly facility at the Jet Propulsion Laboratory (Pasadena, CA) was being monitored, H2O2-resistant bacterial strains were repeatedly isolated from various surface locations. H2O2 is a possible sterilant for spacecraft hardware because it is a low-temperature process and compatible with various modern-day spacecraft materials, electronics, and components. Both conventional biochemical testing and molecular analyses identified these strains as Bacillus pumilus. This Bacillus species was found in both unclassified (entrance floors, anteroom, and air-lock) and classified (floors, cabinet tops, and air) locations. Both vegetative cells and spores of several B. pumilus isolates were exposed to 5% liquid H2O2 for 60 min. Spores of each strain exhibited higher resistance than their respective vegetative cells to liquid H2O2. Results indicate that the H2O2 resistance observed in both vegetative cells and spores is strain-specific, as certain B. pumilus strains were two to three times more resistant than a standard Bacillus subtilis dosimetry strain. An example of this trend was observed when the type strain of B. pumilus, ATCC 7061, proved sensitive, whereas several environmental strains exhibited varying degrees of resistance, to H2O2. Repeated isolation of H2O2-resistant strains of B. pumilus in a clean-room is a concern because their persistence might potentially compromise life-detection missions, which have very strict cleanliness and sterility requirements for spacecraft hardware.

  20. DESIGN AND TESTING OF SUB-SLAB DEPRESSURIZATION FOR RADON MITIGATION IN NORTH FLORIDA HOUSES - PART I. PERFORMANCE AND DURABILITY - VOLUME 2. DATA APPENDICES

    EPA Science Inventory

    The report gives results of a demonstration/research project to evaluate sub-slab depressurization (SSD) techniques for radon mitigation in North Florida where the housing stock is primarily slab-on-grade and the sub-slab medium typically consists of native soil and sand. Objecti...

  1. DESIGN AND TESTING OF SUB-SLAB DEPRESSURIZATION FOR RADON MITIGATION IN NORTH FLORIDA HOUSES - PART I. PERFORMANCE AND DURABILITY - VOLUME 1. TECHNICAL REPORT

    EPA Science Inventory

    The report gives results of a demonstration/research project to evaluate sub-slab depressurization (SSD) techniques for radon mitigation in North Florida where the housing stock is primarily slab-on-grade and the sub-slab medium typically consists of native soil and sand. Objecti...

  2. Analysis of surface wave propagation in a grounded dielectric slab covered by a resistive sheet

    NASA Technical Reports Server (NTRS)

    Shively, David G.

    1992-01-01

    Both parallel and perpendicular polarized surface waves are known to propagate on lossless and lossy grounded dielectric slabs. Surface wave propagation on a grounded dielectric slab covered with a resistive sheet is considered. Both parallel and perpendicular polarizations are examined. Transcendental equations are derived for each polarization and are solved using iterative techniques. Attenuation and phase velocity are shown for representative geometries. The results are applicable to both a grounded slab with a resistive sheet and an ungrounded slab covered on each side with a resistive sheet.

  3. Drug release from slabs and the effects of surface roughness.

    PubMed

    Kalosakas, George; Martini, Dimitra

    2015-12-30

    We discuss diffusion-controlled drug release from slabs or thin films. Analytical and numerical results are presented for slabs with flat surfaces, having a uniform thickness. Then, considering slabs with rough surfaces, the influence of a non-uniform slab thickness on release kinetics is numerically investigated. The numerical release profiles are obtained using Monte Carlo simulations. Release kinetics is quantified through the stretched exponential (or Weibull) function and the resulting dependence of the two parameters of this function on the thickness of the slab, for flat surfaces, and the amplitude of surface fluctuations (or the degree of thickness variability) in case of roughness. We find that a higher surface roughness leads to a faster drug release. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Two innovative solutions based on fibre concrete blocks designed for building substructure

    NASA Astrophysics Data System (ADS)

    Pazderka, J.; Hájek, P.

    2017-09-01

    Using of fibers in a high-strength concrete allows reduction of the dimensions of small precast concrete elements, which opens up new ways of solution for traditional construction details in buildings. The paper presents two innovative technical solutions for building substructure: The special shaped plinth block from fibre concrete and the fibre concrete elements for new technical solution of ventilated floor. The main advantages of plinth block from fibre concrete blocks (compared with standard plinth solutions) is: easier and faster assembly, higher durability and thanks to the air cavity between the vertical part of the block, the building substructure reduced moisture level of structures under the waterproofing layer and a comprehensive solution to the final surface of building plinth as well as the surface of adjacent terrain. The ventilated floor based on fibre concrete precast blocks is an attractive structural alternative for tackling the problem of increased moisture in masonry in older buildings, lacking a functional waterproof layer in the substructure.

  5. The study of the transition regime between slab and mixed slab-toroidal electron temperature gradient modes in a basic experiment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Balbaky, Abed; Sokolov, Vladimir; Sen, Amiya K.

    2015-05-15

    Electron temperature gradient (ETG) modes are suspected sources of anomalous electron thermal transport in magnetically confined plasmas as in tokamaks. Prior work in the Columbia Linear Machine (CLM) has been able to produce and identify slab ETG modes in a slab geometry [Wei et al., Phys. Plasmas 17, 042108 (2010)]. Now by modifying CLM to introduce curvature to the confining axial magnetic field, we have excited mixed slab-toroidal modes. Linear theory predicts a transition between slab and toroidal ETG modes when (k{sub ∥}R{sub c})/(k{sub y}ρ) ∼1 [J. Kim and W. Horton, Phys. Fluids B 3, 1167 (1991)]. We observe changesmore » in the mode amplitude for levels of curvature R{sub c}{sup −1}≪(k{sub ∥,slab})/(k{sub ⊥}ρ) , which may be explained by reductions in k{sub ∥} in the transition from slab to mixed slab-toroidal modes, as also predicted by theory. We present mode amplitude scaling as a function of magnetic field curvature. Over the range of curvature available in CLM experimentally we find a modest increase in saturated ETG potential fluctuations (∼1.5×), and a substantial increase in the power density of individual mode peaks (∼4–5×)« less

  6. Deep Subducction in a Compressible Mantle: Observations and Theory

    NASA Astrophysics Data System (ADS)

    King, S. D.

    2017-12-01

    Our understanding of slab dynamics is primarily based on the results of numerical models of subduction. In such models coherent, cold slabs are clearly visible from the surface of the Earth to the core mantle boundary. In contrast, fast seismic anomalies associated with cold subducted slabs are difficult to identify below 1500-2000 km in tomographic models of Earth's mantle. One explanation for this has been the resolution, or lack thereof, of seismic tomography in the mid-mantle region; however in this work I will explore the impact of compressibility on the dynamics of subducting slabs, specifically shear heating of the slab and latent heat of phase transformations. Most geodynamic models of subduction have used an incompressible formulation, thus because subducted slabs are assumed to be cold and stiff, the primary means of thermal equilibration is conduction. With an assumed sinking velocity of approximately 0.1 m/yr, a subducted slab reaches the core-mantle boundary in approximately 30 Myrs—too fast for significant conductive cooling of the downgoing slab. In this work I consider a whole-mantle geometry and include both phase transformations with associated latent heat and density changes from the olivine-wadsleyite-ringwoodite-bridgmanite system and the pyroxene-garnet system. The goal of this work is to understand both the eventual fate and thermal evolution of slabs beneath the transition zone.

  7. Extraordinary wavelength reduction in terahertz graphene-cladded photonic crystal slabs

    PubMed Central

    Williamson, Ian A. D.; Mousavi, S. Hossein; Wang, Zheng

    2016-01-01

    Photonic crystal slabs have been widely used in nanophotonics for light confinement, dispersion engineering, nonlinearity enhancement, and other unusual effects arising from their structural periodicity. Sub-micron device sizes and mode volumes are routine for silicon-based photonic crystal slabs, however spectrally they are limited to operate in the near infrared. Here, we show that two single-layer graphene sheets allow silicon photonic crystal slabs with submicron periodicity to operate in the terahertz regime, with an extreme 100× wavelength reduction from graphene’s large kinetic inductance. The atomically thin graphene further leads to excellent out-of-plane confinement, and consequently photonic-crystal-slab band structures that closely resemble those of ideal two-dimensional photonic crystals, with broad band gaps even when the slab thickness approaches zero. The overall photonic band structure not only scales with the graphene Fermi level, but more importantly scales to lower frequencies with reduced slab thickness. Just like ideal 2D photonic crystals, graphene-cladded photonic crystal slabs confine light along line defects, forming waveguides with the propagation lengths on the order of tens of lattice constants. The proposed structure opens up the possibility to dramatically reduce the size of terahertz photonic systems by orders of magnitude. PMID:27143314

  8. Demountable externally anchored low-stress magnet system and related method

    DOEpatents

    Powell, James; Hsieh, Shih-Yung; Lehner, John R.

    1981-01-01

    Toroidal field coils are interlaced with other toroidal structures and are operated under supercooled conditions. To facilitate demounting the toroidal field coils, which are supercooled, they are made in the form of connected segments constituting coils of polygonal form. The segments may be rectilinear in form, but some may also be U-shaped or L-shaped. The segments are detachable from one another and are supported in load relieving manner. Power devices are used to displace the segments to facilitate removal of the coils from the aforesaid toroidal structures and to provide for the accommodation of dimensional changes and stresses due to thermal and magnetic conditions. The segments are formed of spaced parallel conductive slabs with the slabs of one segment being interdigitated with the slabs of the adjacent segment. The interdigitated slabs may be soldered together or slidingly engaged. The slabs are shaped to accommodate superconductors and to provide passages for a cooling medium. The slabs are moreover separated by insulator slabs with which they form a coil structure which is jacketed.

  9. Modified creep and shrinkage prediction model B3 for serviceability limit state analysis of composite slabs

    NASA Astrophysics Data System (ADS)

    Gholamhoseini, Alireza

    2016-03-01

    Relatively little research has been reported on the time-dependent in-service behavior of composite concrete slabs with profiled steel decking as permanent formwork and little guidance is available for calculating long-term deflections. The drying shrinkage profile through the thickness of a composite slab is greatly affected by the impermeable steel deck at the slab soffit, and this has only recently been quantified. This paper presents the results of long-term laboratory tests on composite slabs subjected to both drying shrinkage and sustained loads. Based on laboratory measurements, a design model for the shrinkage strain profile through the thickness of a slab is proposed. The design model is based on some modifications to an existing creep and shrinkage prediction model B3. In addition, an analytical model is developed to calculate the time-dependent deflection of composite slabs taking into account the time-dependent effects of creep and shrinkage. The calculated deflections are shown to be in good agreement with the experimental measurements.

  10. KSC-08pd3247

    NASA Image and Video Library

    2008-10-17

    CAPE CANAVERAL, Fla. - Workers position Ares IX upper stage segments’ ballast assemblies along the floor of high bay 4 in the Vehicle Assembly Building at NASA’s Kennedy Space Center, part of the preparations for the test of the Ares IX rocket. These ballast assemblies will be installed in the upper stage 1 and 7 segments and will mimic the mass of the fuel. Their total weight is approximately 160,000 pounds. The test launch of the Ares IX in 2009 will be the first designed to determine the flight-worthiness of the Ares I rocket. Ares I is an in-line, two-stage rocket that will transport the Orion crew exploration vehicle to low-Earth orbit. The Ares I first stage will be a five-segment solid rocket booster based on the four-segment design used for the space shuttle. Ares I’s fifth booster segment allows the launch vehicle to lift more weight and reach a higher altitude before the first stage separates from the upper stage, which ignites in midflight to propel the Orion spacecraft to Earth orbit. Photo credit: NASA/Kim Shiflett

  11. KSC-08pd3246

    NASA Image and Video Library

    2008-10-17

    CAPE CANAVERAL, Fla. - Workers lower an Ares IX upper stage segments’ ballast assembly onto the floor of high bay 4 in the Vehicle Assembly Building at NASA’s Kennedy Space Center, part of the preparations for the test of the Ares IX rocket. These ballast assemblies will be installed in the upper stage 1 and 7 segments and will mimic the mass of the fuel. Their total weight is approximately 160,000 pounds. The test launch of the Ares IX in 2009 will be the first designed to determine the flight-worthiness of the Ares I rocket. Ares I is an in-line, two-stage rocket that will transport the Orion crew exploration vehicle to low-Earth orbit. The Ares I first stage will be a five-segment solid rocket booster based on the four-segment design used for the space shuttle. Ares I’s fifth booster segment allows the launch vehicle to lift more weight and reach a higher altitude before the first stage separates from the upper stage, which ignites in midflight to propel the Orion spacecraft to Earth orbit. Photo credit: NASA/Kim Shiflett

  12. KSC-08pd3249

    NASA Image and Video Library

    2008-10-17

    CAPE CANAVERAL, Fla. - The Ares IX upper stage segments’ ballast assemblies have arrived at NASA’s Kennedy Space Center and are positioned along the floor of high bay 4 in the Vehicle Assembly Building, part of the preparations for the test of the Ares IX rocket. These ballast assemblies will be installed in the upper stage 1 and 7 segments and will mimic the mass of the fuel. Their total weight is approximately 160,000 pounds. The test launch of the Ares IX in 2009 will be the first designed to determine the flight-worthiness of the Ares I rocket. Ares I is an in-line, two-stage rocket that will transport the Orion crew exploration vehicle to low-Earth orbit. The Ares I first stage will be a five-segment solid rocket booster based on the four-segment design used for the space shuttle. Ares I’s fifth booster segment allows the launch vehicle to lift more weight and reach a higher altitude before the first stage separates from the upper stage, which ignites in midflight to propel the Orion spacecraft to Earth orbit. Photo credit: NASA/Kim Shiflett

  13. KSC-08pd3248

    NASA Image and Video Library

    2008-10-17

    CAPE CANAVERAL, Fla. - Ares IX upper stage segments’ ballast assemblies are positioned along the floor of high bay 4 in the Vehicle Assembly Building at NASA’s Kennedy Space Center, part of the preparations for the test of the Ares IX rocket. These ballast assemblies will be installed in the upper stage 1 and 7 segments and will mimic the mass of the fuel. Their total weight is approximately 160,000 pounds. The test launch of the Ares IX in 2009 will be the first designed to determine the flight-worthiness of the Ares I rocket. Ares I is an in-line, two-stage rocket that will transport the Orion crew exploration vehicle to low-Earth orbit. The Ares I first stage will be a five-segment solid rocket booster based on the four-segment design used for the space shuttle. Ares I’s fifth booster segment allows the launch vehicle to lift more weight and reach a higher altitude before the first stage separates from the upper stage, which ignites in midflight to propel the Orion spacecraft to Earth orbit. Photo credit: NASA/Kim Shiflett

  14. KSC-08pd3250

    NASA Image and Video Library

    2008-10-17

    CAPE CANAVERAL, Fla. - The Ares IX upper stage segments’ ballast assemblies have arrived at NASA’s Kennedy Space Center and are positioned along the floor of high bay 4 in the Vehicle Assembly Building, part of the preparations for the test of the Ares IX rocket. These ballast assemblies will be installed in the upper stage 1 and 7 segments and will mimic the mass of the fuel. Their total weight is approximately 160,000 pounds. The test launch of the Ares IX in 2009 will be the first designed to determine the flight-worthiness of the Ares I rocket. Ares I is an in-line, two-stage rocket that will transport the Orion crew exploration vehicle to low-Earth orbit. The Ares I first stage will be a five-segment solid rocket booster based on the four-segment design used for the space shuttle. Ares I’s fifth booster segment allows the launch vehicle to lift more weight and reach a higher altitude before the first stage separates from the upper stage, which ignites in midflight to propel the Orion spacecraft to Earth orbit. Photo credit: NASA/Kim Shiflett

  15. The FLAME-slab method for electromagnetic wave scattering in aperiodic slabs

    NASA Astrophysics Data System (ADS)

    Mansha, Shampy; Tsukerman, Igor; Chong, Y. D.

    2017-12-01

    The proposed numerical method, "FLAME-slab," solves electromagnetic wave scattering problems for aperiodic slab structures by exploiting short-range regularities in these structures. The computational procedure involves special difference schemes with high accuracy even on coarse grids. These schemes are based on Trefftz approximations, utilizing functions that locally satisfy the governing differential equations, as is done in the Flexible Local Approximation Method (FLAME). Radiation boundary conditions are implemented via Fourier expansions in the air surrounding the slab. When applied to ensembles of slab structures with identical short-range features, such as amorphous or quasicrystalline lattices, the method is significantly more efficient, both in runtime and in memory consumption, than traditional approaches. This efficiency is due to the fact that the Trefftz functions need to be computed only once for the whole ensemble.

  16. SU-E-T-52: A New Device for Quality Assurance of a Single Isocenter Technique for the Simultaneous Treatment of Multiple Brain Metastases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Maurer, J; Sintay, B; Varchena, V

    2015-06-15

    Purpose: Comprehensive quality assurance (QA) of a single isocenter technique for the simultaneous treatment of multiple brain metastases is presently impractical due to the time consuming nature of measuring each lesion’s dose on film or with a micro-chamber. Three dimensional diode array and full field film measurements are sometimes used to evaluate these plans, but gamma analysis may not reveal local errors that have significant effects on one or a few of several targets. This work aimed to design, build and test a phantom to simplify comprehensive measurement and evaluation. Methods: A phantom was designed with 28 stackable slabs. Themore » top and bottom slabs are 1.5 centimeters (cm) in thickness, and central 26 slabs are 0.5 cm thick. When assembled with radiochromic film in all 27 gaps, the phantom measures 16.5 x 15 x 19 cm. Etchings were designed to aide in identification of specific film planes on computed tomography (CT) images and correlation of individual PTVs with closest bisecting planes. Patient verification plans with a total of 16 PTVs were calculated on the phantom CT, and test deliveries both with and without couch kicks were performed to test the ability to identify correct film placements and subsequent PTV specific dose distributions on the films. Results: Bisecting planes corresponding to PTV locations were easily identified, and PTV specific dose distributions were clear for all 16 targets. For deliveries with couch kicks, the phantom PTV dose distributions closely approximated those calculated on the patient’s CT. For deliveries without couch kicks, PTV specific dosimetry was also possible, although the distributions had ‘ghosts’ equaling the number of couch kicks, with distance between ghosts increasing with distance from the isocenter. Conclusion: A new phantom facilitates fast comprehensive commissioning validation and PTV specific dosimetry for a single isocenter technique for treating multiple brain metastases. This work was partially funded by CIRS, Inc.« less

  17. Design of a Slab Waveguide Multiaperture Fourier Spectrometer for Water Vapor Measurements in Earth's Atmosphere

    NASA Astrophysics Data System (ADS)

    Sinclair, Kenneth; Florjańczyk, Mirosław; Solheim, Brian; Scott, Alan; Quine, Ben; Cheben, Pavel

    Concept, theory and design of a new type of waveguide device, a multiaperture Fourier-transform planar waveguide spectrometer[1], implemented as a prototype instrument is pre-sented. The spectrometer's objective is to demonstrate the ability of the new slab waveguide technology for application in remote sensing instruments[2]. The spectrometer will use a limb viewing configuration to detect the 1.36um waveband allowing concentrations of water vapor in earth's atmosphere to be measured[3]. The most challenging aspects of the design, assembly and calibration are presented. Focus will be given to the effects of packaging the spectrometer and interfacing to the detector array. Stress-induced birefringence will affect the performance of the waveguides, therefore the design of a stress-free mounting over a range of temperatures is important. Spectral retrieval algo-rithms will have to correct for expected fabrication errors in the waveguides. Data processing algorithms will also be developed to correct for non-uniformities of input brightness through the array, making use of MMI output couplers to capture both the in-phase and anti-phase interferometer outputs. A performance assessment of an existing breadboard spectrometer will demonstrate the capability of the instrument. REFERENCES 1. M. Florjáczyk, P. Cheben, S. Janz, A. Scott, B. Solheim, and D.-X. Xu, "Multiaper-n ture planar waveguide spectrometer formed by arrayed Mach-Zehnder interferometers," Opt. Expr. 15(26), 18176-18189 (2007). 2. M. Florjáczyk, P. Cheben, S. Janz, B. Lamontagne, J. n Lapointe, A. Scott, B. Solheim, and D.-X. Xu, "Slab waveguiode spatial heterodyne spectrom-eters for remote sensing from space," Optical sensors 2009. Proceedings of the SPIE, Volume 7356 (2009)., pp. 73560V-73560V-7 (2009). 3. A. Scott, M. Florjáczyk, P. Cheben, S. Janz, n B. Solheim, and D.-X. Xu, "Micro-interferometer with high throughput for remote sensing." MOEMS and Miniaturized Systems VIII. Proceedings of the SPIE, Volume 7208 (2009)., pp. 72080G-72080G-7 (2009).

  18. Leaky unstable modes and electromagnetic radiation amplification by an anisotropic plasma slab

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vagin, K. Yu., E-mail: vagin@sci.lebedev.ru; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru

    2015-09-15

    The interaction between electromagnetic radiation and a photoionized plasma slab with an anisotropic electron velocity distribution is studied. It is shown that the fields of leaky modes are amplified due to the development of aperiodic instability in the slab, which leads to an increase in both the reflected and transmitted fields. The transmitted field can significantly increase only if the slab thickness does not exceed the ratio of the speed of light to the electron plasma frequency, whereas there is no upper bound on the slab thickness for the reflected signal to be amplified.

  19. High energy efficient solid state laser sources. [slab geometry laser sources

    NASA Technical Reports Server (NTRS)

    Byer, R. L.

    1983-01-01

    Slab glass performance studies demonstate 18 J of output at 2 Hz with 2.3% wall plug efficiency. The goal is to achieve 10 J per pulse at 10 Hz and 3% wall plug efficiency during the next annual period. The slab concept was extended to Nd:YAG and to Nd:GGG. To date over 80 W of CW output power at 2% efficiency was generated in slab Nd:YAG. A multiplexed slab Nd:YAG pre-amplifier was invented and a Nd:YAG oscillator was demonstrated with 100kHz linewidth for eventual use in wind velocity measurements.

  20. MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE ...

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

    MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE RUN OUT INCLUDES THE TRAVELING TORCH WHICH CUTS SLABS TO DESIRED LENGTH, AN IDENTIFICATION SYSTEM TO INDICATE HEAT NUMBER AND TRACE IDENTITY OF EVERY SLAB, AND A DEBURRING DEVICE TO SMOOTH SLABS. AT LEFT OF ROLLS IS THE DUMMY BAR. DUMMY BAR IS INSERTED UP THROUGH CONTAINMENT SECTION INTO MOLD PRIOR TO START OF CAST. WHEN STEEL IS INTRODUCED INTO MOLD IT CONNECTS WITH BAR AS CAST BEGINS, AT RUN OUT DUMMY BAR DISCONNECTS AND IS STORED. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  1. MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE ...

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

    MULTIPLE SETS OF TWIN SLABS ON THE RUN OUT. THE RUN OUT INCLUDES THE TRAVELING TORCH WHICH CUTS SLABS TO DESIRED LENGTH, AN IDENTIFICATION SYSTEM TO INDICATE HEAT NUMBER AND TRACE IDENTITY OF EVERY SLAB, AND A DEBURRING DEVICE TO SMOOTH SLABS. AT LEFT OF ROLLS IS THE DUMMY BAR. DUMMY BAR IS INSERTED UP THROUGH CONTAINMENT SECTION INTO MOLD PRIOR TO START OF CAST. WHEN STEEL IS INTRODUCED INTO MOLD IT CONNECTS WITH BAR AS CAST BEGINS, AT RUN OUT DUMMY BAR DISCONNECTS AND IS STORED - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  2. Cause Analysis on the Void under Slabs of Cement Concrete Pavement

    NASA Astrophysics Data System (ADS)

    Wen, Li; Zhu, Guo Xin; Baozhu

    2017-06-01

    This paper made a systematic analysis on the influence of the construction, environment, water and loads on the void beneath road slabs, and also introduced the formation process of structural void and pumping void, and summarizes the deep reasons for the bottom of the cement concrete pavement. Based on the analysis above, this paper has found out the evolution law of the void under slabs which claimed that the void usually appeared in the slab corners and then the cross joint, resulting void in the four sides with the void area under the front slab larger than the rear one.

  3. Shear Wave Velocities in the Pampean Flat Slab Region from Rayleigh Wave Tomography: Implications for Crustal Composition and Upper Mantle Hydration

    NASA Astrophysics Data System (ADS)

    Porter, R. C.; Gilbert, H. J.; Zandt, G.; Beck, S. L.; Warren, L. M.; Calkins, J. A.; Alvarado, P. M.; Anderson, M. L.

    2011-12-01

    The Pampean flat slab region, located in Chile and western Argentina between 29° and 34° S, is characterized by the subducting Nazca plate assuming a sub-horizontal geometry for ~300 km laterally before resuming a more "normal" angle of subduction. The onset of flat slab subduction is associated with the cessation of regional arc related volcanism and the migration of deformation inboard from the high Andes into the thin-skinned Precordillera and thick-skinned Sierras Pampeanas. Developing a better understanding of this region's geology is of particular importance, as it is an ideal area to study flat slab subduction and serves as a modern analogue to Laramide flat slab subduction in the western US. To study the crustal and mantle structure in the region, we combine ambient noise tomography and ballistic surface wave tomography to produce a regional 3D shear wave velocity model that encompasses flat slab subduction in the north and normal subduction geometry in the south, allowing for a comparison of the two. Results from this work show that shear velocities within the upper crust are largely determined by composition, with sedimentary basins and areas with active volcanism exhibiting slower velocities than basement cored uplifts and other bedrock exposures. Though surface waves are not particularly sensitive to the depth of sharp velocity contrasts, we observe an eastward increase in shear velocity at depth that correlates with an eastward decrease in crustal thickness. In both the slab and overlying mantle, we observe significant variations in shear wave velocity. North of 32° S, where flat slab subduction is occurring, the Nazca plate contains low-velocity zones (LVZs) beneath the high Andes and Precordillera that are not present in the east beneath the Sierras Pampeanas. An opposite transition is observed in the overlying mantle, which changes from fast in the west to slow in the east. Both of these observations are consistent with an initially hydrated slab dehydrating and releasing water into the overlying mantle. Within this region we also observe a LVZ immediately above the slab as the subduction angle steepens. This zone potentially represents asthenosphere or hydrated lithospheric mantle. South of 32° S, where subduction is occurring at a more normal angle, the slab is visible as a high-velocity body with a low-velocity mantle wedge present beneath the arc and back arc. The variations in slab and upper mantle shear velocities are consistent with a hydrated flat slab and the presence of a LVZ above the flat slab as it steepens suggests that water is being transported to a significant depth or that an asthenospheric wedge is present between the slab and cratonic lithosphere.

  4. Pacific slab beneath northeast China revealed by regional and teleseismic waveform modeling

    NASA Astrophysics Data System (ADS)

    WANG, X.; Chen, Q. F.; Wei, S.

    2015-12-01

    Accurate velocity and geometry of the slab is essential for better understanding of the thermal, chemical structure of the mantle earth, as well as geodynamics. Recent tomography studies show similar morphology of the subducting Pacific slab beneath northeast China, which was stagnant in the mantle transition zone with thickness of more than 200km and an average velocity perturbation of ~1.5% [Fukao and Obayashi, 2013]. Meanwhile, waveform-modeling studies reveal that the Pacific slab beneath Japan and Kuril Island has velocity perturbation up to 5% and thickness up to 90km [Chen et al., 2007; Zhan et al., 2014]. These discrepancies are probably caused by the smoothing and limited data coverage in the tomographic inversions. Here we adopted 1D and 2D waveform modeling methods to study the fine structure of Pacific slab beneath northeast China using dense regional permanent and temporary broadband seismic records. The residual S- and P-wave travel time, difference between data and 1D synthetics, shows significant difference between the eastern and western stations. S-wave travel time residuals indicate 5-10s earlier arrivals for stations whose ray path lies within the slab, compared with those out of the slab. Teleseimic waveforms were used to rule out the major contribution of the possible low velocity structure above 200km. Furthermore, we use 2D finite-difference waveform modeling to confirm the velocity perturbation and geometry of the slab. Our result shows that the velocity perturbation in the slab is significantly higher than those reported in travel-time tomography studies. ReferencesChen, M., J. Tromp, D. Helmberger, and H. Kanamori (2007), Waveform modeling of the slab beneath Japan, J. Geophys. Res.-Solid Earth, 112(B2), 19, doi:10.1029/2006jb004394.Fukao, Y., and M. Obayashi (2013), Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity, J. Geophys. Res.-Solid Earth, 118(11), 5920-5938, doi:10.1002/2013jb010466.Zhan, Z. W., D. V. Helmberger, and D. Z. Li (2014), Imaging subducted slab structure beneath the Sea of Okhotsk with teleseismic waveforms, Phys. Earth Planet. Inter., 232, 30-35, doi:10.1016/j.pepi.2014.03.008.

  5. Low-Cost Radon Reduction Pilot Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rose, William B.; Francisco, Paul W.; Merrin, Zachary

    The aim of the research was to conduct a primary scoping study on the impact of air sealing between the foundation and the living space on radon transport reduction across the foundation-living space floor assembly. Fifteen homes in the Champaign, Illinois area participated in the study. These homes were instrumented for hourly continuous radon measurements and simultaneous temperature and humidity the foundation was improved. However, this improved isolation did not lead to significant reductions in radon concentration in the living space. Other factors such as outdoor temperature were shown to have an impact on radon concentration.

  6. KSC-2009-2462

    NASA Image and Video Library

    2009-04-01

    CAPE CANAVERAL, Fla. – In High Bay 4 of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, the Ares I-X upper stage simulator service module/service adapter segment (foreground) is being prepared for its move to a stand. Other segments are placed and stacked on the floor around it. Ares I-X is the test vehicle for the Ares I, which is part of the Constellation Program to return men to the moon and beyond. The Ares I-X is targeted for launch in July 2009. Photo credit: NASA/Kim Shiflett

  7. Present-day stress field in subduction zones: Insights from 3D viscoelastic models and data

    NASA Astrophysics Data System (ADS)

    Petricca, Patrizio; Carminati, Eugenio

    2016-01-01

    3D viscoelastic FE models were performed to investigate the impact of geometry and kinematics on the lithospheric stress in convergent margins. Generic geometries were designed in order to resemble natural subduction. Our model predictions mirror the results of previous 2D models concerning the effects of lithosphere-mantle relative flow on stress regimes, and allow a better understanding of the lateral variability of the stress field. In particular, in both upper and lower plates, stress axes orientations depend on the adopted geometry and axes rotations occur following the trench shape. Generally stress axes are oriented perpendicular or parallel to the trench, with the exception of the slab lateral tips where rotations occur. Overall compression results in the upper plate when convergence rate is faster than mantle flow rate, suggesting a major role for convergence. In the slab, along-strike tension occurs at intermediate and deeper depths (> 100 km) in case of mantle flow sustaining the sinking lithosphere and slab convex geometry facing mantle flow or in case of opposing mantle flow and slab concave geometry facing mantle flow. Along-strike compression is predicted in case of sustaining mantle flow and concave slabs or in case of opposing mantle flow and convex slabs. The slab stress field is thus controlled by the direction of impact of mantle flow onto the slab and by slab longitudinal curvature. Slab pull produces not only tension in the bending region of subducted plate but also compression where upper and lower plates are coupled. A qualitative comparison between results and data in selected subductions indicates good match for South America, Mariana and Tonga-Kermadec subductions. Discrepancies, as for Sumatra-Java, emerge due to missing geometric (e.g., occurrence of fault systems and local changes in the orientation of plate boundaries) and rheological (e.g., plasticity associated with slab bending, anisotropy) complexities in the models.

  8. Slab detachment during continental collision: Influence of crustal rheology and interaction with lithospheric delamination

    NASA Astrophysics Data System (ADS)

    Duretz, T.; Gerya, T. V.

    2013-08-01

    Collision between continents can lead to the subduction of continental material. If the crust remains coupled to the downgoing slab, a large buoyancy force is generated. This force slows down convergence and promotes slab detachment. If the crust resists to subduction, it may decouple from the downgoing slab and be subjected to buoyant extrusion. We employ two-dimensional thermo-mechanical modelling to study the importance of crustal rheology on the evolution of subduction-collision systems. We propose simple quantifications of the mechanical decoupling between lithospheric levels (σ*) and the potential for buoyant extrusion of the crust (ξ*). The modelling results indicate that a variable crustal rheological structure results in slab detachment, delamination, or the combination of both mechanisms. A strong crust provides coupling at the Moho (low σ*) and remains coherent during subduction (low ξ). It promotes deep subduction of the crust (180 km) and slab detachment. Exhumation occurs in coherent manners via eduction and thrusting. Slab detachment triggers the development of topography (> 4.5 km) close to the suture. A contrasting style of collision occurs using a weak crustal rheology. Mechanical decoupling at the Moho (high σ*) promotes the extrusion of the crust (high ξ), disabling slab detachment. Ongoing shortening leads to buckling of the crust and development of topography on the lower plate. Collisions involving rheologically layered crust allow decoupling at mid-crustal depths. This structure favours both the extrusion of upper crust and the subduction of the lower crust. Such collisions are successively affected by delamination and slab detachment. Topography develops together with the buoyant extrusion of crust onto the foreland and is further amplified by slab detachment. Our results suggest that the occurrence of both delamination (Apennines) and slab detachment (Himalayas) in orogens may indicate differences in the initial crustal structure of subducting continental plates in these regions.

  9. Tearing, segmentation, and backstepping of subduction in the Aegean: New insights from seismicity

    NASA Astrophysics Data System (ADS)

    Bocchini, G. M.; Brüstle, A.; Becker, D.; Meier, T.; van Keken, P. E.; Ruscic, M.; Papadopoulos, G. A.; Rische, M.; Friederich, W.

    2018-06-01

    This study revisits subduction processes at the Hellenic Subduction Zone (HSZ) including tearing, segmentation, and backstepping, by refining the geometry of the Nubian slab down to 150-180 km depth using well-located hypocentres from global and local seismicity catalogues. At the western termination of the HSZ, the Kefalonia Transform Fault marks the transition between oceanic and continental lithosphere subducting to the south and to the north of it, respectively. A discontinuity is suggested to exist between the two slabs at shallow depths. The Kefalonia Transform Fault is interpreted as an active Subduction-Transform-Edge-Propagator-fault formed as consequence of faster trench retreat induced by the subduction of oceanic lithosphere to the south of it. A model reconstructing the evolution of the subduction system in the area of Peloponnese since 34 Ma, involving the backstepping of the subduction to the back-side of Adria, provides seismological evidence that supports the single-slab model for the HSZ and suggests the correlation between the downdip limit of the seismicity to the amount of subducted oceanic lithosphere. In the area of Rhodes, earthquake hypocentres indicate the presence of a NW dipping subducting slab that rules out the presence of a NE-SW striking Subduction-Transform-Edge-Propagator-fault in the Pliny-Strabo trenches region. Earthquake hypocentres also allow refining the slab tear beneath southwestern Anatolia down to 150-180 km depth. Furthermore, the distribution of microseismicity shows a first-order slab segmentation in the region between Crete and Karpathos, with a less steep and laterally wider slab segment to the west and a steeper and narrower slab segment to the east. Thermal models indicate the presence of a colder slab beneath the southeastern Aegean that leads to deepening of the intermediate-depth seismicity. Slab segmentation affects the upper plate deformation that is stronger above the eastern slab segment and the seismicity along the interplate seismogenic zone.

  10. A dynamic model for slab development associated with the 2015 Mw 7.9 Bonin Islands deep earthquak

    NASA Astrophysics Data System (ADS)

    Zhan, Z.; Yang, T.; Gurnis, M.

    2016-12-01

    The 680 km deep May 30, 2015 Mw 7.9 Bonin Islands earthquake is isolated from the nearest earthquakes by more than 150 km. The geodynamic context leading to this isolated deep event is unclear. Tomographic models and seismicity indicate that the morphology of the west-dipping Pacific slab changes rapidly along the strike of the Izu-Bonin-Mariana trench. To the north, the Izu-Bonin section of the Pacific slab lies horizontally above the 660 km discontinuity and extends more than 500 km westward. Several degrees south, the Mariana section dips vertically and penetrates directly into the lower mantle. The observed slab morphology is consistent with plate reconstructions suggesting that the northern section of the IBM trench retreated rapidly since the late Eocene while the southern section of the IBM trench was relatively stable during the same period. We suggest that the location of the isolated 2015 Bonin Islands deep earthquake can be explained by the buckling of the Pacific slab beneath the Bonin Islands. We use geodynamic models to investigate the slab morphology, temperature and stress regimes under different trench motion histories. Models confirm previous results that the slab often lies horizontally within the transition zone when the trench retreats, but buckles when the trench position becomes fixed with respect to the lower mantle. We show that a slab-buckling model is consistent with the observed deep earthquake P-axis directions (assumed to be the axis of principal compressional stress) regionally. The influences of various physical parameters on slab morphology, temperature and stress regime are investigated. In the models investigated, the horizontal width of the buckled slab is no more than 400 km.

  11. Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

    NASA Astrophysics Data System (ADS)

    Chik, T. N. T.; Kamil, M. R. H.; Yusoff, N. A.

    2018-04-01

    Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations. The vibration level on the slab is acceptable within the limit that have been used by Gordon.

  12. Focusing fluids towards the arc: the role of rheology and reactions

    NASA Astrophysics Data System (ADS)

    Wilson, C. R.; Spiegelman, M. W.

    2014-12-01

    Aqueous fluids released from the down-going slab in subduction zones are generally thought to be the cause of arc volcanism. However there is a significant discrepancy between the consistent location of the volcanic front with respect to intermediate depth earthquakes (e.g. 100+/-40 km; England et al., GJI, 2004, Syracuse & Abers, G-cubed, 2006) and the large depth range over which dehydration reactions are predicted to occur in the slab (e.g. 80-250 km; van Keken et al., JGR, 2011). By coupling the fluid flow to the solid rheology through compaction pressure, recent numerical models (Wilson et al., EPSL, 2014) demonstrated a number of focusing mechanisms that can be invoked to explain this apparent discrepancy. Most notable among these were permeability channels within the slab. These were shown to be highly effective in transporting fluid from deeper fluid sources along the slab towards the shallowest source. In the presence of these channels the majority of the fluid is released into the mantle wedge far shallower and closer to the arc than it was originally generated. While observations consistent with free fluids in the slab have been reported (e.g. Shiina et al., GRL, 2013), it is possible that changing the rheology and reactivity of the slab can change the efficiency of in-slab transport. We present a series of simplified model problems of fluid flow within the slab and mantle wedge demonstrating the potential effect of these processes on fluid flux. In particular, pseudo-1D models show that if fluids can efficiently rehydrate slab minerals, then these reactions can shut down fluid pathways within the slab, resulting in deeper release of fluid into the mantle wedge. However, the behavior in full subduction zone models remains to be determined.

  13. Mantle plumes in the vicinity of subduction zones

    NASA Astrophysics Data System (ADS)

    Mériaux, C. A.; Mériaux, A.-S.; Schellart, W. P.; Duarte, J. C.; Duarte, S. S.; Chen, Z.

    2016-11-01

    We present three-dimensional deep-mantle laboratory models of a compositional plume within the vicinity of a buoyancy-driven subducting plate with a fixed trailing edge. We modelled front plumes (in the mantle wedge), rear plumes (beneath the subducting plate) and side plumes with slab/plume systems of buoyancy flux ratio spanning a range from 2 to 100 that overlaps the ratios in nature of 0.2-100. This study shows that 1) rising side and front plumes can be dragged over thousands of kilometres into the mantle wedge, 2) flattening of rear plumes in the trench-normal direction can be initiated 700 km away from the trench, and a plume material layer of lesser density and viscosity can ultimately almost entirely underlay a retreating slab after slab/plume impact, 3) while side and rear plumes are not tilted until they reach ∼600 km depth, front plumes can be tilted at increasing depths as their plume buoyancy is lessened, and rise at a slower rate when subjected to a slab-induced downwelling, 4) rear plumes whose buoyancy flux is close to that of a slab, can retard subduction until the slab is 600 km long, and 5) slab-plume interaction can lead to a diversity of spatial plume material distributions into the mantle wedge. We discuss natural slab/plume systems of the Cascadia/Bowie-Cobb, and Nazca/San Felix-Juan Fernandez systems on the basis of our experiments and each geodynamic context and assess the influence of slab downwelling at depths for the starting plumes of Java, Coral Sea and East Solomon. Overall, this study shows how slab/plume interactions can result in a variety of geological, geophysical and geochemical signatures.

  14. The influence of rheological weakening and yield stress on the interaction of slabs with the 670 km discontinuity

    NASA Astrophysics Data System (ADS)

    Čížková, Hana; van Hunen, Jeroen; van den Berg, Arie P.; Vlaar, Nico J.

    2002-06-01

    Results of high resolution seismic tomography showing subducting slabs deflected in the transition zone and thickened in the lower mantle seem to call for slab material weaker than inferred from mineral physics deformation mechanisms. A possible mechanism suggested by several authors could be the weakening due to grain size reduction, which should occur in the cold portion of fast slabs after an exothermic phase transition at a depth of 400 km. Since the amount of weakening as well as the rate of subsequent strengthening due to the grain growth are not precisely known, we present here a parametric study of slab behavior in the transition zone and upper part of the lower mantle. We simulate a subducting slab in a two-dimensional (2-D) Cartesian box in the numerical model with composite rheology including diffusion creep, dislocation creep and a general stress limiting rheology approximating Peierl's creep. We concentrate on two rheologic effects: the dynamic effect of slab weakening due to grain size reduction at the phase boundary and the effect of yield stress of stress limiting rheology. The effect of trench migration on slab deformation is also included in our study. Results show that the slab ability to penetrate into the lower mantle is not significantly affected by a trench retreat in the absence of grain size weakening. However, in case of a 4 cm/yr trench retreat, grain size weakening provides a viable mechanism to deflect the slab in the transition zone, provided that stress limiting deformation mechanism would limit the effective viscosity outside the areas of grain size weakening to about 1024 Pa s.

  15. Constraining Slab Breakoff Induced Magmatism through Numerical Modelling

    NASA Astrophysics Data System (ADS)

    Freeburn, R.; Van Hunen, J.; Maunder, B. L.; Magni, V.; Bouilhol, P.

    2015-12-01

    Post-collisional magmatism is markedly different in nature and composition than pre-collisional magmas. This is widely interpreted to mark a change in the thermal structure of the system due to the loss of the oceanic slab (slab breakoff), allowing a different source to melt. Early modelling studies suggest that when breakoff takes place at depths shallower than the overriding lithosphere, magmatism occurs through both the decompression of upwelling asthenopshere into the slab window and the thermal perturbation of the overriding lithosphere (Davies & von Blanckenburg, 1995; van de Zedde & Wortel, 2001). Interpretations of geochemical data which invoke slab breakoff as a means of generating magmatism mostly assume these shallow depths. However more recent modelling results suggest that slab breakoff is likely to occur deeper (e.g. Andrews & Billen, 2009; Duretz et al., 2011; van Hunen & Allen, 2011). Here we test the extent to which slab breakoff is a viable mechanism for generating melting in post-collisional settings. Using 2-D numerical models we conduct a parametric study, producing models displaying a range of dynamics with breakoff depths ranging from 150 - 300 km. Key models are further analysed to assess the extent of melting. We consider the mantle wedge above the slab to be hydrated, and compute the melt fraction by using a simple parameterised solidus. Our models show that breakoff at shallow depths can generate a short-lived (< 3 Myr) pulse of mantle melting, through the hydration of hotter, undepleted asthenosphere flowing in from behind the detached slab. However, our results do not display the widespread, prolonged style of magmatism, observed in many post-collisional areas, suggesting that this magmatism may be generated via alternative mechanisms. This further implies that using magmatic observations to constrain slab breakoff is not straightforward.

  16. Imaging the slab structure in the Alpine region by high-resolution P-wave tomography

    NASA Astrophysics Data System (ADS)

    Guillot, Stéphane; Zhao, Liang; Paul, Anne; Malusà, Marco G.; Xu, Xiaobing; Zheng, Tianyu; Solarino, stefano; Schwartz, Stéphane; Dumont, Thierry; Salimbeni, Simone; Aubert, Coralie; Pondrelli, Silvia; Wang, Qingchen; Zhu, Rixiang

    2017-04-01

    Based upon a finite-frequency inversion of traveltimes, we computed a new high-resolution tomography model using P-wave data from 527 broadband seismic stations, both from permanent networks and temporary experiments (Zhao et al., 2016). This model provides an improved image of the slab structure in the Alpine region, and fundamental pin-points for the analysis of Cenozoic magmatism, (U)HP metamorphism and Alpine topography. Our results document the lateral continuity of the European slab from the Western to the Central Alps, and the down-dip slab continuity beneath the Central Alps, ruling out the hypothesis of slab breakoff to explain Cenozoic Alpine magmatism. A low velocity anomaly is observed in the upper mantle beneath the core of the Western Alps, pointing to dynamic topography effects (Malusà et al., this meeting). A NE-dipping Adriatic slab, consistent with Dinaric subduction, is possibly observed beneath the Eastern Alps, whereas the laterally continuous Adriatic slab of the Northern Apennines shows major gaps at the boundary with the Southern Apennines, and becomes near vertical in the Alps-Apennines transition zone. Tear faults accommodating opposite-dipping subductions during Alpine convergence may represent reactivated lithospheric faults inherited from Tethyan extension. Our results suggest that the interpretations of previous tomography results that include successive slab breakoffs along the Alpine-Zagros-Himalaya orogenic belt might be proficiently reconsidered. Malusà M.G. et alii (2017) On the potential asthenospheric linkage between Apenninic slab rollback and Alpine topographic uplift: insights from P wave tomography and seismic anisotropy analysis. EGU 2017. Zhao L. et alii (2016), Continuity of the Alpine slab unraveled by high-resolution P wave tomography. J. Geophys. Res., doi:10.1002/2016JB013310.

  17. Kinematic variables and water transport control the formation and location of arc volcanoes.

    PubMed

    Grove, T L; Till, C B; Lev, E; Chatterjee, N; Médard, E

    2009-06-04

    The processes that give rise to arc magmas at convergent plate margins have long been a subject of scientific research and debate. A consensus has developed that the mantle wedge overlying the subducting slab and fluids and/or melts from the subducting slab itself are involved in the melting process. However, the role of kinematic variables such as slab dip and convergence rate in the formation of arc magmas is still unclear. The depth to the top of the subducting slab beneath volcanic arcs, usually approximately 110 +/- 20 km, was previously thought to be constant among arcs. Recent studies revealed that the depth of intermediate-depth earthquakes underneath volcanic arcs, presumably marking the slab-wedge interface, varies systematically between approximately 60 and 173 km and correlates with slab dip and convergence rate. Water-rich magmas (over 4-6 wt% H(2)O) are found in subduction zones with very different subduction parameters, including those with a shallow-dipping slab (north Japan), or steeply dipping slab (Marianas). Here we propose a simple model to address how kinematic parameters of plate subduction relate to the location of mantle melting at subduction zones. We demonstrate that the location of arc volcanoes is controlled by a combination of conditions: melting in the wedge is induced at the overlap of regions in the wedge that are hotter than the melting curve (solidus) of vapour-saturated peridotite and regions where hydrous minerals both in the wedge and in the subducting slab break down. These two limits for melt generation, when combined with the kinematic parameters of slab dip and convergence rate, provide independent constraints on the thermal structure of the wedge and accurately predict the location of mantle wedge melting and the position of arc volcanoes.

  18. Long-life slab replacement concrete : [summary].

    DOT National Transportation Integrated Search

    2015-04-01

    Concrete slab replacement projects in Florida have demonstrated a high incidence of : replacement slab cracking. Causes of cracking have not been reliably determined. University of South Florida researchers : sought to identify the factors or : param...

  19. Experimental validation of systematically designed acoustic hyperbolic meta material slab exhibiting negative refraction

    NASA Astrophysics Data System (ADS)

    Christiansen, Rasmus E.; Sigmund, Ole

    2016-09-01

    This Letter reports on the experimental validation of a two-dimensional acoustic hyperbolic metamaterial slab optimized to exhibit negative refractive behavior. The slab was designed using a topology optimization based systematic design method allowing for tailoring the refractive behavior. The experimental results confirm the predicted refractive capability as well as the predicted transmission at an interface. The study simultaneously provides an estimate of the attenuation inside the slab stemming from the boundary layer effects—insight which can be utilized in the further design of the metamaterial slabs. The capability of tailoring the refractive behavior opens possibilities for different applications. For instance, a slab exhibiting zero refraction across a wide angular range is capable of funneling acoustic energy through it, while a material exhibiting the negative refractive behavior across a wide angular range provides lensing and collimating capabilities.

  20. Electromagnetic Tunneling and Resonances in Pseudochiral Omega Slabs

    PubMed Central

    Razzaz, Faroq; Alkanhal, Majeed A. S.

    2017-01-01

    This paper presents theoretical investigation of the electromagnetic wave tunneling and anomalous transmission around the trapped modes in a pseudochiral omega slab. The dispersion relation, the conditions of the trapped modes, and the evanescent wave coupling and tunneling in two different reciprocal pseudochiral omega slab structures are derived. The Berreman’s matrix method is applied to obtain the transmission coefficients across the pseudochiral omega slab. When the structure is perturbed, a resonance phenomenon is detected around the trapped modes. This resonance results in transmission anomalies (total transmission and total reflection) and dramatic field amplifications around the trapped modes. The number of the discrete trapped modes and then the resonance frequencies are prescribed by the parameters of the pseudochiral omega slab such as the value of the omega parameter and its orientation and the slab thickness. PMID:28165058

  1. Overturned Alboran slab beneath westernmost Mediterranean

    NASA Astrophysics Data System (ADS)

    Sun, D.; Miller, M. S.

    2017-12-01

    The geological evolution of the westernmost Mediterranean holds an important piece of the puzzle of how whole western Mediterranean evolved due to the convergence of Africa with Eurasia. The idea of continuous slab roll back acting a prominent force in this region is strongly supported by tomographic images with near vertical high velocity structure connecting the surface beneath the Alboran domain [Spakman and Wortel, 2004; Bezada et al., 2013]. However, the slab shape, width, and sharpness of its edges are not well resolved. Here, we use the waveforms recorded from the PICASSO (XB) array and IberArray (IA) for the deep 2010 earthquake beneath Granada to study the detailed Alboran slab structure. We found: (1) A low velocity structure (7 km thickness, δVs = -20%) surrounding the earthquake to explain the second arrivals observed in many stations at Spain. (2) A thin low velocity layer sits on the bottom of the high velocity slab-like structure to explain the high frequency second arrivals and long coda after the P and S arrivals on stations in the Rif Mountains of Morocco. The most feasible explanation of the low velocity structure is the dehydrated surface of the slab lithosphere extending from the 600 km to the shallow mantle. However, such geometry is contradictory with our observation, which the low velocity layer is at the bottom of the slab. We proposed that the Albora slab had undergone significant "roll-over" movement, which overturned the slab surface.

  2. Juan de Fuca slab geometry and its relation to Wadati-Benioff zone seismicity

    USGS Publications Warehouse

    McCrory, Patricia A.; Blair, J. Luke; Waldhause, Felix; Oppenheimer, David H.

    2012-01-01

    A new model of the subducted Juan de Fuca plate beneath western North America allows first-order correlations between the occurrence of Wadati-Benioff zone earthquakes and slab geometry, temperature, and hydration state. The geo-referenced 3D model, constructed from weighted control points, integrates depth information from earthquake locations and regional seismic velocity studies. We use the model to separate earthquakes that occur in the Cascadia forearc from those that occur within the underlying Juan de Fuca plate and thereby reveal previously obscured details regarding the spatial distribution of earthquakes. Seismicity within the slab is most prevalent where the slab is warped beneath northwestern California and western Washington suggesting that slab flexure, in addition to expected metamorphic dehydration processes, promotes earthquake occurrence within the subducted oceanic plate. Earthquake patterns beneath western Vancouver Island are consistent with slab dehydration processes. Conversely, the lack of slab earthquakes beneath western Oregon is consistent with an anhydrous slab. Double-differenced relocated seismicity resolves a double seismic zone within the slab beneath northwestern California that strongly constrains the location of the plate interface and delineates a cluster of seismicity 10 km above the surface that includes the 1992 M7.1 Mendocino earthquake. We infer that this earthquake ruptured a surface within the Cascadia accretionary margin above the Juan de Fuca plate. We further speculate that this earthquake is associated with a detached fragment of former Farallon plate. Other subsurface tectonic elements within the forearc may have the potential to generate similar damaging earthquakes.

  3. Mass Housing Using GFRG Panels: A Sustainable, Rapid and Affordable Solution

    NASA Astrophysics Data System (ADS)

    Cherian, Philip; Paul, Shinto; Krishna, S. R. Gouri; Menon, Devdas; Meher Prasad, A.

    2017-06-01

    This work gives an overview of research and development carried out at IIT Madras, using glass fibre reinforced gypsum (GFRG) panels, to provide an innovative solution for rapid and affordable mass housing. The GFRG panels (124 mm thick), made from recycled industrial waste gypsum (from the fertilizer industry), are prefabricated in 3 m × 12 m sizes with cellular cavities inside, which can be filled with reinforced concrete wherever required and can be used as walls as well as floor slabs. The tests carried out (over the past 12 years) establish the performance of GFRG building systems to resist gravity and lateral loads as a load-bearing system (without beams and columns) in multi-storeyed buildings up to 8-10 storeys, with adequate strength, serviceability, durability and ductility. A two-storeyed four-apartment demonstration building has also been successfully constructed in the IIT Madras campus and presently a mass housing scheme (40 apartment units) using this technology is being demonstrated at Nellore. A structural design code has also been approved by the Bureau of Indian Standards, based on the extensive studies carried out on GFRG building systems.

  4. Optimization of Regional Geodynamic Models for Mantle Dynamics

    NASA Astrophysics Data System (ADS)

    Knepley, M.; Isaac, T.; Jadamec, M. A.

    2016-12-01

    The SubductionGenerator program is used to construct high resolution, 3D regional thermal structures for mantle convection simulations using a variety of data sources, including sea floor ages and geographically referenced 3D slab locations based on seismic observations. The initial bulk temperature field is constructed using a half-space cooling model or plate cooling model, and related smoothing functions based on a diffusion length-scale analysis. In this work, we seek to improve the 3D thermal model and test different model geometries and dynamically driven flow fields using constraints from observed seismic velocities and plate motions. Through a formal adjoint analysis, we construct the primal-dual version of the multi-objective PDE-constrained optimization problem for the plate motions and seismic misfit. We have efficient, scalable preconditioners for both the forward and adjoint problems based upon a block preconditioning strategy, and a simple gradient update is used to improve the control residual. The full optimal control problem is formulated on a nested hierarchy of grids, allowing a nonlinear multigrid method to accelerate the solution.

  5. High-quality slab-based intermixing method for fusion rendering of multiple medical objects.

    PubMed

    Kim, Dong-Joon; Kim, Bohyoung; Lee, Jeongjin; Shin, Juneseuk; Kim, Kyoung Won; Shin, Yeong-Gil

    2016-01-01

    The visualization of multiple 3D objects has been increasingly required for recent applications in medical fields. Due to the heterogeneity in data representation or data configuration, it is difficult to efficiently render multiple medical objects in high quality. In this paper, we present a novel intermixing scheme for fusion rendering of multiple medical objects while preserving the real-time performance. First, we present an in-slab visibility interpolation method for the representation of subdivided slabs. Second, we introduce virtual zSlab, which extends an infinitely thin boundary (such as polygonal objects) into a slab with a finite thickness. Finally, based on virtual zSlab and in-slab visibility interpolation, we propose a slab-based visibility intermixing method with the newly proposed rendering pipeline. Experimental results demonstrate that the proposed method delivers more effective multiple-object renderings in terms of rendering quality, compared to conventional approaches. And proposed intermixing scheme provides high-quality intermixing results for the visualization of intersecting and overlapping surfaces by resolving aliasing and z-fighting problems. Moreover, two case studies are presented that apply the proposed method to the real clinical applications. These case studies manifest that the proposed method has the outstanding advantages of the rendering independency and reusability. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  6. Work Term Assignment Spring 2017

    NASA Technical Reports Server (NTRS)

    Sico, Mallory

    2017-01-01

    My tour in the Engineering Robotics directorate exceeded my expectations. I learned lessons about Creo, manufacturing and assembly, collaboration, and troubleshooting. During my first tour, last spring, I used Creo on a smaller project, but had limited experience with it before starting in the Dynamic Systems Test branch this spring. I gained valuable experience learning assembly design, sheet metal design and designing with intent for manufacturing and assembly. These skills came from working both on the hatch and the floor. I also learned to understand the intent of other designers on models I worked with. While redesigning the floor, I was modifying an existing part and worked to understand what the previous designer had done to make it fit with the new model. Through working with the machine shop and in the mock-up, I learned much more about manufacturing and assembly. I used a Dremel, rivet gun, belt sander, and countersink for the first time. Through taking multiple safety training for different machine shops, I learned new machine shop safety skills specific to each one. This semester also gave me new collaborative opportunities. I collaborated with engineers within my branch as well as with Human Factors and the building 10 machine shop. This experience helped me learn how to design for functionality and assembly, not only for what would be easiest in my designs. In addition to these experiences, I learned many lessons in troubleshooting. I was the first person in my office to use a Windows 10 computer. This caused unexpected issues with NASA services and programs, such as the Digital Data Management Server (DDMS). Because of this, I gained experience finding solutions to lockout and freeze issues as well as Creo specific settings. These will be useful skills to have in the future and will be implemented in future rotations. This co-op tour has motivated me more to finish my degree and pursue my academic goals. I intend to take a machining Career Gateway Elective in the Fall to improve my skills in building as well as designing with manufacturing intent. I am also inspired to take more mechatronics CGE courses before I graduate to learn more about the crossover between mechanical and electrical engineering. This semester, I worked on multiple projects and had the opportunity to learn from engineers of different disciplines. I became proficient in Creo 2.0, a program I had not used significantly before. I finished modifying the hatch for 3D print and made sizeable modifications to the nose floor support design. I also gained hands-on experience that will be useful in my engineering career in the future. I would consider all of these major achievements from this spring semester. Lastly, I learned to ask more questions and to search for the right people to find answers which I know will be a valuable skill in the future. This summer, I will be completing my last rotation in the Flight Operations Directorate at Ellington Air Field. After this last tour, I will be returning to school for the Fall, Spring and Summer. I will graduate in August of 2018. I am looking forward to learning more about the different jobs available to engineers. This division works directly with many different types of aircrafts and I am excited to learn more about this focus of engineering. The Aircraft Operations Division values team work greatly and I intend to improve my interpersonal skills by working with them this summer.

  7. Injected polyurethane slab jacking : interim report

    DOT National Transportation Integrated Search

    2000-09-01

    Conventional methods for raising in-place concrete slabs to align roadway sections or to counteract subsidence requires pressure-injecting grout under the slab. As other transportation organizations have had success with the URETEK Method, which util...

  8. Injected polyurethane slab jacking : final report.

    DOT National Transportation Integrated Search

    2002-06-01

    Conventional methods for raising in-place concrete slabs to align roadway sections or to counteract subsidence requires pressure-injecting grout under the slab. As other transportation organizations have had success with the URETEK Method, which util...

  9. van der Waals torque and force between anisotropic topological insulator slabs

    NASA Astrophysics Data System (ADS)

    Lu, Bing-Sui

    2018-01-01

    We investigate the character of the van der Waals (vdW) torque and force between two coplanar and dielectrically anisotropic topological insulator (TI) slabs separated by a vacuum gap in the nonretardation regime, where the optic axes of the slabs are each perpendicular to the normal direction to the slab-gap interface and also generally differently oriented from each other. We find that in addition to the magnetoelectric coupling strength, the anisotropy can also influence the sign of the vdW force, viz., a repulsive vdW force can become attractive if the anisotropy is increased sufficiently. In addition, the vdW force oscillates as a function of the angular difference between the optic axes of the TI slabs, being most repulsive/least attractive (least repulsive/most attractive) for angular differences that are integer (half-integer) multiples of π . Our third finding is that the vdW torque for TI slabs is generally weaker than that for ordinary dielectric slabs. Our work provides an instance in which the vector potential appears in a calculation of the vdW interaction for which the limit is nonretarded or static.

  10. Anomalous deepening of a belt of intraslab earthquakes in the Pacific slab crust under Kanto, central Japan: Possible anomalous thermal shielding, dehydration reactions, and seismicity caused by shallower cold slab material

    USGS Publications Warehouse

    Hasegawa, A.; Nakajima, J.; Kita, S.; Okada, T.; Matsuzawa, T.; Kirby, S.H.

    2007-01-01

    A belt of intraslab seismicity in the Pacific slab crust parallel to iso-depth contours of the plate interface has been found beneath Hokkaido and Tohoku. Hypocenter relocations have shown that this seismic belt does not run parallel to but obliquely to the iso-depth contours beneath Kanto, deepening toward the north from ???100 km to ???140 km depth. The depth limit of the contact zone with the overlying Philippine Sea slab is located close to and parallel to this obliquely oriented seismic belt, suggesting that the deepening of the seismic belt there is caused by the contact with the overlying slab. The contact with this cold slab hinders the heating of the Pacific slab crust by hot mantle wedge, which would cause delay of eclogite-forming phase transformations and hence deepening of the seismic belt there. The depth limit of the subducting low-velocity crust also deepens toward the north, supporting this idea. Copyright 2007 by the American Geophysical Union.

  11. Comparison of discrete ordinate and Monte Carlo simulations of polarized radiative transfer in two coupled slabs with different refractive indices.

    PubMed

    Cohen, D; Stamnes, S; Tanikawa, T; Sommersten, E R; Stamnes, J J; Lotsberg, J K; Stamnes, K

    2013-04-22

    A comparison is presented of two different methods for polarized radiative transfer in coupled media consisting of two adjacent slabs with different refractive indices, each slab being a stratified medium with no change in optical properties except in the direction of stratification. One of the methods is based on solving the integro-differential radiative transfer equation for the two coupled slabs using the discrete ordinate approximation. The other method is based on probabilistic and statistical concepts and simulates the propagation of polarized light using the Monte Carlo approach. The emphasis is on non-Rayleigh scattering for particles in the Mie regime. Comparisons with benchmark results available for a slab with constant refractive index show that both methods reproduce these benchmark results when the refractive index is set to be the same in the two slabs. Computed results for test cases with coupling (different refractive indices in the two slabs) show that the two methods produce essentially identical results for identical input in terms of absorption and scattering coefficients and scattering phase matrices.

  12. Seismic evidence for hydration of the Central American slab: Guatemala through Costa Rica

    NASA Astrophysics Data System (ADS)

    Syracuse, E. M.; Thurber, C. H.

    2011-12-01

    The Central American subduction zone exhibits a wide variability in along-arc slab hydration as indicated by geochemical studies. These studies generally show maximum slab contributions to magma beneath Nicaragua and minimum contributions beneath Costa Rica, while intermediate slab fluid contributions are found beneath El Salvador and Guatemala. Geophysical studies suggest strong slab serpentinization and fluid release beneath Nicaragua, and little serpentinization beneath Costa Rica, but the remainder of the subduction zone is poorly characterized seismically. To obtain an integrated seismic model for the Central American subduction zone, we combine 250,000 local seismic arrivals and 1,000,000 differential arrivals for 6,500 shallow and intermediate-depth earthquakes from the International Seismic Centre, the Central American Seismic Center, and the temporary PASSCAL TUCAN array. Using this dataset, we invert for Vp, Vs, and hypocenters using a variable-mesh double-difference tomography algorithm. By observing low-Vp areas within the normally high-Vp slab, we identify portions of the slab that are likely to contain serpentinized mantle, and thus contribute to higher degrees of melting and higher volatile components observable in arc lavas.

  13. Too much slab waving in South America? Wet plumes as an alternative to flat slab steepening as the cause of back arc large volcanic provinces

    NASA Astrophysics Data System (ADS)

    Booker, J. R.; Burd, A. I.

    2013-12-01

    A widely held view is that the Nazca Slab under western S. America acts like a tattered flag waving in the wind: It is segmented and the dip angle of segments flap up and down with time. There are presently two flat segments - one under Peru and the other, the "Pampean" flat slab (centered around 31S) under central Chile and Argentina. Both are correlated with subduction of buoyant crust of oceanic aseismic ridges, complete cessation of Andean arc volcanism and very thick crust. It has been argued that the waxing and waning of flat subduction is responsible for much of the time variations in tectonics and volcanism up to 800 km east of the S. American coast for at least 100 MA. For instance, the back arc Payenia igneous plateau (35-38S) and the Somuncura igneous plateau (40.5-43S) are both thought to follow from the steepening of flat slabs at about 2 and 27 MA. Each flat slab existed for more than 5 MA. However, the case for the existence of these flat slabs rests heavily on volcanism with "arc signature" hundreds of km east of the modern volcanic arc at a time when an asthenospheric wedge would be in its final stages of being squeezed out of the space between the slab and the lithosphere. Arc signature can be summarized as the geochemical consequence of mantle melting in the presence of water. If there is a source of water in the mantle other than a shallow slab, the strongest argument for a flat slab dissolves. We have found two electrically conductive plumes rising from below 350 km near the top of the Mantle Transition Zone (MTZ). One passes through a window in the Pampean flat slab but does not penetrate the lithosphere. The other rises under Payenia. The maximum resistivity at the core of these plumes is less than 10 Ohm-m. Partial melt can explain such low resistivity, but will not be buoyant and rise from below 350 km. We propose that the low resistivity is more likely due to water and that we are seeing "wet plumes" that have been proposed to explain volcanism in SW Japan and in mainland China. Wet plumes are an MTZ instability triggered by a subducted slab that has stagnated in the MTZ. Their rise is driven by the lower density of hydrous minerals and their melting at the base of the lithosphere can produce the same geochemical consequences as a shallow slab. Seismic tomography of the MTZ beneath S. America supports stagnant slabs beneath our plumes. We conclude, therefore that many of the flat slabs proposed in S. America may not have existed.

  14. Follow up of injected polyurethane slab jacking.

    DOT National Transportation Integrated Search

    2003-08-01

    GLENN JACKSON BRIDGE FOLLOW-UP REPORT The elevation monitoring in the report entitled Injected Polyurethane Slab Jacking (Soltesz 2000) is continued in this current report. The elevations of the concrete slabs are being monitored to see if polyuretha...

  15. Imaging performance of an isotropic negative dielectric constant slab.

    PubMed

    Shivanand; Liu, Huikan; Webb, Kevin J

    2008-11-01

    The influence of material and thickness on the subwavelength imaging performance of a negative dielectric constant slab is studied. Resonance in the plane-wave transfer function produces a high spatial frequency ripple that could be useful in fabricating periodic structures. A cost function based on the plane-wave transfer function provides a useful metric to evaluate the planar slab lens performance, and using this, the optimal slab dielectric constant can be determined.

  16. Regional body-wave tomography of the Peruvian flat slab

    NASA Astrophysics Data System (ADS)

    Young, Bissett E.

    Local travel time data were used to create three dimensional tomography models of Vp and Vs above the flat slab in southern Peru, where the Nazca plate subducts subhorizontally beneath the continental lithosphere. The Peruvian flat slab segment corresponds to a gap in the volcanic arc and far-field thick-skinned deformation in the Eastern Cordillera. Despite ongoing research, there is little consensus on the causes and consequences of flat slab subduction. We present results from regional body-wave tomography which show high S-wave velocities above the slab for a region that coincides with the location of the Nazca ridge, a bathymetric high subducting at ~15°S. We propose that fast S-wave arrivals can be explained by mantle anisotropy. We attribute low Vs observed in the mantle north of the ridge to the presence of hydrous phases, resulting from the depth dependent dehydration of amphibole in an area where the slab is deeper.

  17. Mantle flow through a tear in the Nazca slab inferred from shear wave splitting

    NASA Astrophysics Data System (ADS)

    Lynner, Colton; Anderson, Megan L.; Portner, Daniel E.; Beck, Susan L.; Gilbert, Hersh

    2017-07-01

    A tear in the subducting Nazca slab is located between the end of the Pampean flat slab and normally subducting oceanic lithosphere. Tomographic studies suggest mantle material flows through this opening. The best way to probe this hypothesis is through observations of seismic anisotropy, such as shear wave splitting. We examine patterns of shear wave splitting using data from two seismic deployments in Argentina that lay updip of the slab tear. We observe a simple pattern of plate-motion-parallel fast splitting directions, indicative of plate-motion-parallel mantle flow, beneath the majority of the stations. Our observed splitting contrasts previous observations to the north and south of the flat slab region. Since plate-motion-parallel splitting occurs only coincidentally with the slab tear, we propose mantle material flows through the opening resulting in Nazca plate-motion-parallel flow in both the subslab mantle and mantle wedge.

  18. Numerical analysis of the shifting slabs applied in a wireless power transfer system to enhance magnetic coupling

    NASA Astrophysics Data System (ADS)

    Dong, Yayun; Yang, Xijun; Jin, Nan; Li, Wenwen; Yao, Chen; Tang, Houjun

    2017-05-01

    Shifting medium is a kind of metamaterial, which can optically shift a space or an object a certain distance away from its original position. Based on the shifting medium, we propose a concise pair of shifting slabs covering the transmitting or receiving coil in a two-coil wireless power transfer system to decrease the equivalent distance between the coils. The electromagnetic parameters of the shifting slabs are calculated by transformation optics. Numerical simulations validate that the shifting slabs can approximately shift the electromagnetic fields generated by the covered coil; thus, the magnetic coupling and the efficiency of the system are enhanced while remaining the physical transmission distance unchanged. We also verify the advantages of the shifting slabs over the magnetic superlens. Finally, we provide two methods to fabricate shifting slabs based on split-ring resonators.

  19. Dislocation-free strained silicon-on-silicon by in-place bonding

    NASA Astrophysics Data System (ADS)

    Cohen, G. M.; Mooney, P. M.; Paruchuri, V. K.; Hovel, H. J.

    2005-06-01

    In-place bonding is a technique where silicon-on-insulator (SOI) slabs are bonded by hydrophobic attraction to the underlying silicon substrate when the buried oxide is undercut in dilute HF. The bonding between the exposed surfaces of the SOI slab and the substrate propagates simultaneously with the buried oxide etching. As a result, the slabs maintain their registration and are referred to as "bonded in-place". We report the fabrication of dislocation-free strained silicon slabs from pseudomorphic trilayer Si/SiGe/SOI by in-place bonding. Removal of the buried oxide allows the compressively strained SiGe film to relax elastically and induce tensile strain in the top and bottom silicon films. The slabs remain bonded to the substrate by van der Waals forces when the wafer is dried. Subsequent annealing forms a covalent bond such that when the upper Si and the SiGe layer are removed, the bonded silicon slab remains strained.

  20. Thermal, Petrologic, and Structural Conditions for the September 2017 M=8.2 and M=7.1 intra-slab earthquakes in Mexico

    NASA Astrophysics Data System (ADS)

    Wang, K.; Gao, X.; Rogers, G. C.

    2017-12-01

    The M=8.2 Tehuantepec and M=7.1 Puebla earthquakes of September 2017 are similar to the 1999 Oaxaca (M=7.5, Mexico), 2001 Geiyo (M=6.7, Nankai), and 2001 Nisqually (M=6.8, Cascadia) earthquakes. All these events are normal-faulting events in the 40-60 km depth range within young and warm subducting slabs. They all ruptured the mantle part of the slab. To investigate the thermal and petrologic conditions of these earthquakes, we have developed finite element thermal models in the areas of the two September events. Along the northern transect for the M=7.1 event, where the age of the incoming plate is 13.5 Ma, the slab geometry is well constrained by previous receiver function and earthquake location studies. Two available hypocenter locations of the main shock fall within or at the lower boundary of our model-predicted zone of serpentine (antigorite) stability in the slab mantle. Along the southern transect for the M=8.2 event, where the age of the incoming plate is 25.5 Ma, the slab geometry is less well known, and we have considered two published geometrical models. Several available hypocenter locations of the main shock are within or below the serpentine stability zone, depending on which slab geometry is assumed. Most of the rupture zone is shallower than the hypocenter. The model results support the following hypothesis. The two September earthquakes probably ruptured pre-existing normal faults that extended into the oceanic mantle and had been locally hydrated prior to and during the beginning phase of subduction. The earthquakes may have initiated at the dehydration boundary of antigorite or chlorite, facilitated by elevated pore fluid pressure (dehydration embrittlement). Most of the rupture was in the uppermost mantle part of the slab but may have involved parts of the slab crust. That large intra-slab earthquakes of this type tend to involve mantle rupture has been explained as due to the structural condition caused by warm-slab metamorphism (Wang et al., 2004): The upper crust of the slab is too fragmented due to metamorphic densification, but hydrated deep-cutting faults can produce large earthquakes in the more coherent mantle and lower crust. Wang, K., J. F. Cassidy, I. Wada, and A. J. Smith (2004), Effects of metamorphic crustal densification on earthquake size in warm slabs, Geophys. Res. Lett., 31, L01605, doi:10.1029/2003GL018644.

  1. Evidences of a Stalled-slab Beneath the Coast Ranges, California, From Seismicity and Converted Phases

    NASA Astrophysics Data System (ADS)

    Cao, A.; Liu, K. H.; Gao, S. S.

    2001-12-01

    In spite of numerous geophysical studies, the existence and geometry of a stalled slab beneath the Coast Ranges remains vague. In this study we use the distribution of mantle earthquakes and P-to-S converted phases from tilt interfaces to address the problem. Based on the CNSS catalog, in the period between 01/1960 and 04/2001, there were about 450 earthquakes occurred at depth larger than 35 km in the vicinity of the Coast Ranges. When plotted along east-west cross-sections, those earthquakes show a clear slab-like image, similar to the upper part of classic Benioff zones along subducting oceanic slabs. One of such cross-sections, which has a width of 20 km and a latitude of 39N, is located in the so-called 'slabless window' suggested by several previous geologic and geophysic studies, implying the existence of a stalled-slab along the cross-section. The mantle earthquakes can be explained as the result of stress concentration caused by heterogeneities in elastic properties associated with the cold slab, and of changes in mineralogical phases in the upper-most mantle in and around the slab. The existence of the slab is supported by clear azimuthal variations of the amplitude and arrival time of P-to-S converted phases from a tilt interface at about 70 km depth recorded by a broadband seismic station in the area. Our analysis shows that the converted phase is probably from a subducted oceanic lithosphere dipping to the east. The strike of the slab is approximately parallel to the Coast Ranges.

  2. Four-Pass Coupler for Laser-Diode-Pumped Solid-State Laser

    NASA Technical Reports Server (NTRS)

    Coyle, Donald B.

    2008-01-01

    A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original application for which this coupler was conceived involves a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal slab, which, when pumped by a row of laser diodes at a wavelength of 809 nm, lases at a wavelength of 1,064 nm. Heretofore, typically, a thin laser slab has been pumped in two passes, the second pass occurring by virtue of reflection of pump light from a highly reflective thin film on the side opposite the side through which the pump light enters. In two-pass pumping, a Nd:YAG slab having a thickness of 2 mm (which is typical) absorbs about 84 percent of the 809-nm pump light power, leaving about 16 percent of the pump light power to travel back toward the laser diodes. This unused power can cause localized heating of the laser diodes, thereby reducing their lifetimes. Moreover, if the slab is thinner than 2 mm, then even more unused power travels back toward the laser diodes. The four-pass optical coupler captures most of this unused pump light and sends it back to the laser slab for two more passes. As a result, the slab absorbs more pump light, as though it were twice as thick. The gain and laser cavity beam quality of a smaller laser slab in conjunction with this optical coupler can thus be made comparable to those of a larger two-pass-pumped laser slab.

  3. A seismological constraint on the age of a subducting slab: the Huatung basin offshore Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, Y.; Kuo, B.

    2010-12-01

    At the northwestern corner of the Philippine basin, collision and subduction are taking place simultaneously as the Philippine Sea plate is obliquely subducting beneath the Ryukyu trench and NE Taiwan. What is engaging in these processes is the Huatung basin (HB) lithosphere, a small piece of oceanic lithosphere which, unlike the rest of the Philippine Sea plate, is controversial in its age and structure. Because certain ages of lithosphere correspond to certain overall velocity structures, we examine how old the subducting slab of the HB has to be to satisfy seismological observations. We select from broadband seismic networks on Taiwan a rough linear array that points to the events in the Kuril trench region, rendering a slab dipping towards the upcoming P wave field. The slab thus defocuses seismic energy and produces an amplitude low along the array with magnitude and spread controlled by the age of the slab. We employ a 2D finite-difference waveform technique and experimented with 2 types of slab models with various ages: a simplistic conduction model and a high-resolution slab-wedge convection model. The older and thicker the slab, the more widely the predicted amplitude low spreads. Comparison with the observations indicates that the best slab ages fall into 20-50 Ma. This is at odds with the 125 Ma Ar-Ar dating model. Now the issue is not how to make the chronologically old lithosphere seismologically young, but why those basaltic rock samples dated to be old are located on the HB.

  4. Impact of Mantle Wind on Subducting Plate Geometry and Interplate Pressure: Insights From Physical Modelling.

    NASA Astrophysics Data System (ADS)

    Boutelier, D.; Cruden, A. R.

    2005-12-01

    New physical models of subduction investigate the impact of large-scale mantle flow on the structure of the subducted slab and deformation of the downgoing and overriding plates. The experiments comprise two lithospheric plates made of highly filled silicone polymer resting on a model asthenosphere of low viscosity transparent silicone polymer. Subduction is driven by a piston that pushes the subducting plate at constant rate, a slab-pull force due to the relative density of the slab, and a basal drag force exerted by flow in the model asthenosphere. Large-scale mantle flow is imposed by a second piston moving at constant rate in a tunnel at the bottom of the experiment tank. Passive markers in the mantle track the evolution of flow during the experiment. Slab structure is recorded by side pictures of the experiment while horizontal deformation is studied via passive marker grids on top of both plates. The initial mantle flow direction beneath the overriding plate can be sub-horizontal or sub-vertical. In both cases, as the slab penetrates the mantle, the mantle flow pattern changes to accommodate the subducting high viscosity lithosphere. As the slab continues to descend, the imposed flow produces either over- or under-pressure on the lower surface of the slab depending on the initial mantle flow pattern (sub-horizontal or sub-vertical respectively). Over-pressure imposed on the slab lower surface promotes shallow dip subduction while under-pressure tends to steepen the slab. These effects resemble those observed in previous experiments when the overriding plate moves horizontally with respect to a static asthenosphere. Our experiments also demonstrate that a strong vertical drag force (due to relatively fast downward mantle flow) exerted on the slab results in a decrease in strain rate in both the downgoing and overriding plates, suggesting a decrease in interplate pressure. Furthermore, with an increase in drag force deformation in the downgoing plate can switch from compression to extension. The density contrast between the downgoing plate and asthenosphere is varied from 0% to ~2% in order to investigate the relative contributions of mantle flow and slab pull force on the geometry of the slab and tectonic regime (compressional or extensional).

  5. Using thermal and compositional modeling to assess the role of water in Alaskan flat slab subduction

    NASA Astrophysics Data System (ADS)

    Robinson, S. E.; Porter, R. C.; Hoisch, T. D.

    2017-12-01

    Although plate tectonic theory is well established in the geosciences, the mechanisms and details of various plate-tectonics related phenomena are not always well understood. In some ( 10%) convergent plate boundaries, subduction of downgoing oceanic plates is characterized by low angle geometries and is termed "flat slab subduction." The mechanism(s) driving this form of subduction are not well understood. The goal of this study is to explore the role that water plays in these flat slab subduction settings. This is important for a better understanding of the behavior of these systems and for assessing volcanic hazards associated with subduction and slab rollback. In southern Alaska, the Pacific Plate is subducting beneath the North American plate at a shallow angle. This low-angle subduction within the region is often attributed to the subduction of the Yakutat block, a terrane accreting to the south-central coast of Alaska. This flat slab region is bounded by the Aleution arc to the west and the strike-slip Queen Charlotte fault to the east. Temperature and compositional models for a 500-km transect across this subduction zone in Alaska were run for ten million years (the length of time that flat slab subduction has been ongoing in Alaska) and allow for interpretation of present-day conditions at depth. This allows for an evaluation of two hypotheses regarding the role of water in flat-slab regions: (1) slab hydration and dehydration help control slab buoyancy which influences whether flat slab subduction will be maintained or ended. (2) slab hydration/dehydration of the overlying lithosphere impacts deformation within the upper plate as water encourages plate deformation. Preliminary results from thermal modeling using Thermod8 show that cooling of the mantle to 500 °C is predicted down to 100 km depth at 10 million years after the onset of low-angle subduction (representing present-day). Results from compositional modeling in Perple_X show the maximum amount of water that can be held in the system assuming crustal (basalt and metabasalt) and mantle (peridotite) compositions. These models will be compared with seismic velocity models created from EarthScope Transportable Array data in the region in order to determine amounts of serpentinite and other water-bearing rocks within the flat slab subduction system.

  6. Evolutionarily conserved morphogenetic movements at the vertebrate head-trunk interface coordinate the transport and assembly of hypopharyngeal structures.

    PubMed

    Lours-Calet, Corinne; Alvares, Lucia E; El-Hanfy, Amira S; Gandesha, Saniel; Walters, Esther H; Sobreira, Débora Rodrigues; Wotton, Karl R; Jorge, Erika C; Lawson, Jennifer A; Kelsey Lewis, A; Tada, Masazumi; Sharpe, Colin; Kardon, Gabrielle; Dietrich, Susanne

    2014-06-15

    The vertebrate head-trunk interface (occipital region) has been heavily remodelled during evolution, and its development is still poorly understood. In extant jawed vertebrates, this region provides muscle precursors for the throat and tongue (hypopharyngeal/hypobranchial/hypoglossal muscle precursors, HMP) that take a stereotype path rostrally along the pharynx and are thought to reach their target sites via active migration. Yet, this projection pattern emerged in jawless vertebrates before the evolution of migratory muscle precursors. This suggests that a so far elusive, more basic transport mechanism must have existed and may still be traceable today. Here we show for the first time that all occipital tissues participate in well-conserved cell movements. These cell movements are spearheaded by the occipital lateral mesoderm and ectoderm that split into two streams. The rostrally directed stream projects along the floor of the pharynx and reaches as far rostrally as the floor of the mandibular arch and outflow tract of the heart. Notably, this stream leads and engulfs the later emerging HMP, neural crest cells and hypoglossal nerve. When we (i) attempted to redirect hypobranchial/hypoglossal muscle precursors towards various attractants, (ii) placed non-migratory muscle precursors into the occipital environment or (iii) molecularly or (iv) genetically rendered muscle precursors non-migratory, they still followed the trajectory set by the occipital lateral mesoderm and ectoderm. Thus, we have discovered evolutionarily conserved morphogenetic movements, driven by the occipital lateral mesoderm and ectoderm, that ensure cell transport and organ assembly at the head-trunk interface. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  7. Evolutionarily conserved morphogenetic movements at the vertebrate head–trunk interface coordinate the transport and assembly of hypopharyngeal structures

    PubMed Central

    Lours-Calet, Corinne; Alvares, Lucia E.; El-Hanfy, Amira S.; Gandesha, Saniel; Walters, Esther H.; Sobreira, Débora Rodrigues; Wotton, Karl R.; Jorge, Erika C.; Lawson, Jennifer A.; Kelsey Lewis, A.; Tada, Masazumi; Sharpe, Colin; Kardon, Gabrielle; Dietrich, Susanne

    2014-01-01

    The vertebrate head–trunk interface (occipital region) has been heavily remodelled during evolution, and its development is still poorly understood. In extant jawed vertebrates, this region provides muscle precursors for the throat and tongue (hypopharyngeal/hypobranchial/hypoglossal muscle precursors, HMP) that take a stereotype path rostrally along the pharynx and are thought to reach their target sites via active migration. Yet, this projection pattern emerged in jawless vertebrates before the evolution of migratory muscle precursors. This suggests that a so far elusive, more basic transport mechanism must have existed and may still be traceable today. Here we show for the first time that all occipital tissues participate in well-conserved cell movements. These cell movements are spearheaded by the occipital lateral mesoderm and ectoderm that split into two streams. The rostrally directed stream projects along the floor of the pharynx and reaches as far rostrally as the floor of the mandibular arch and outflow tract of the heart. Notably, this stream leads and engulfs the later emerging HMP, neural crest cells and hypoglossal nerve. When we (i) attempted to redirect hypobranchial/hypoglossal muscle precursors towards various attractants, (ii) placed non-migratory muscle precursors into the occipital environment or (iii) molecularly or (iv) genetically rendered muscle precursors non-migratory, they still followed the trajectory set by the occipital lateral mesoderm and ectoderm. Thus, we have discovered evolutionarily conserved morphogenetic movements, driven by the occipital lateral mesoderm and ectoderm, that ensure cell transport and organ assembly at the head–trunk interface. PMID:24662046

  8. Microwave Quantitative NDE Technique for Dielectric Slab Thickness Estimation Using the Music Algorithm

    NASA Astrophysics Data System (ADS)

    Abou-Khousa, M. A.; Zoughi, R.

    2007-03-01

    Non-invasive monitoring of dielectric slab thickness is of great interest in various industrial applications. This paper focuses on estimating the thickness of dielectric slabs, and consequently monitoring their variations, utilizing wideband microwave signals and the MUtiple SIgnal Characterization (MUSIC) algorithm. The performance of the proposed approach is assessed by validating simulation results with laboratory experiments. The results clearly indicate the utility of this overall approach for accurate dielectric slab thickness evaluation.

  9. Tottori earthquakes and Daisen volcano: Effects of fluids, slab melting and hot mantle upwelling

    NASA Astrophysics Data System (ADS)

    Zhao, Dapeng; Liu, Xin; Hua, Yuanyuan

    2018-03-01

    We investigate the 3-D seismic structure of source areas of the 6 October 2000 Western Tottori earthquake (M 7.3) and the 21 October 2016 Central Tottori earthquake (M 6.6) which occurred near the Daisen volcano in SW Japan. The two large events took place in a high-velocity zone in the upper crust, whereas low-velocity (low-V) and high Poisson's ratio (high-σ) anomalies are revealed in the lower crust and upper mantle. Low-frequency micro-earthquakes (M 0.0-2.1) occur in or around the low-V and high-σ zones, which reflect upward migration of magmatic fluids from the upper mantle to the crust under the Daisen volcano. The nucleation of the Tottori earthquakes may be affected by the ascending fluids. The flat subducting Philippine Sea (PHS) slab has a younger lithosphere age and so a higher temperature beneath the Daisen and Tottori area, facilitating the PHS slab melting. It is also possible that a PHS slab window has formed along the extinct Shikoku Basin spreading ridge beneath SW Japan, and mantle materials below the PHS slab may ascend to the shallow area through the slab window. These results suggest that the Daisen adakite magma was affected by the PHS slab melting and upwelling flow in the upper mantle above the subducting Pacific slab.

  10. Meteorological variables associated with deep slab avalanches on persistent weak layers

    USGS Publications Warehouse

    Marienthal, Alex; Hendrikx, Jordy; Birkeland, Karl; Irvine, Kathryn M.

    2014-01-01

    Deep slab avalanches are a particularly challenging avalanche forecasting problem. These avalanches are typically difficult to trigger, yet when they are triggered they tend to propagate far and result in large and destructive avalanches. For this work we define deep slab avalanches as those that fail on persistent weak layers deeper than 0.9m (3 feet), and that occur after February 1st. We utilized a 44-year record of avalanche control and meteorological data from Bridger Bowl Ski Area to test the usefulness of meteorological variables for predicting deep slab avalanches. As in previous studies, we used data from the days preceding deep slab cycles, but we also considered meteorological metrics over the early months of the season. We utilized classification trees for our analyses. Our results showed warmer temperatures in the prior twenty-four hours and more loading over the seven days before days with deep slab avalanches on persistent weak layers. In line with previous research, extended periods of above freezing temperatures led to days with deep wet slab avalanches on persistent weak layers. Seasons with either dry or wet avalanches on deep persistent weak layers typically had drier early months, and often had some significant snow depth prior to those dry months. This paper provides insights for ski patrollers, guides, and avalanche forecasters who struggle to forecast deep slab avalanches on persistent weak layers late in the season.

  11. A dipping, thick Farallon slab below central United States

    NASA Astrophysics Data System (ADS)

    Sun, D.; Gurnis, M.; Saleeby, J.; Helmberger, D. V.

    2015-12-01

    It has been hypothesized that much of the Laramide orogeny was caused by dynamic effects induced by an extensive flat slab during a period of plateau subduction. A particularly thick block containing the Shatsky Rise conjugate, now in the mid-mantle, left a distinctive deformation footprint from southern California to Denver, Colorado. Thus mid-mantle, relic slabs can provide fundamental information about past subduction and the history of plate tectonics if properly imaged. Here we find clear evidence for a northeastward dipping (35° dip), slab-like, but fat (up to 400-500 km thick) seismic anomaly within the top of the lower mantle below the central United States. Using a deep focus earthquake below Spain with direct seismic paths that propagate along the top and bottom of the anomaly, we find that the observed, stacked seismic waveforms recorded with the dense USArray show multi-pathing indicative of sharp top and bottom surfaces. Plate tectonic reconstructions in which the slab is migrated back in time suggest strong coupling of the slab to North America. In combination with the reconstructions, we interpret the structure as arising from eastward dipping Farallon subduction at the western margin of North America during the Cretaceous, in contrast with recent interpretations. The slab could have been fattened through a combination of pure shear thickening during flat-slab subduction and a folding instability during penetration into the lower mantle.

  12. Connecting the surface to the deep: Flat-slab subduction dynamics and the evolution of western Amazonia

    NASA Astrophysics Data System (ADS)

    Eakin, C. M.

    2017-12-01

    Plate tectonics is primarily driven by the subduction of cold dense oceanic slabs. It has yet to be fully understood however how variations in slab morphology and buoyancy influence the surrounding mantle dynamics, and what difference if any is seen at the surface. An excellent natural laboratory to answer such questions is found along the Andean margin where the world's largest flat slab is presently subducting beneath much of Peru. Following the deployment of broadband seismic arrays across the region, mantle flow both beneath and above the flat-slab is investigated using targeted shear-wave splitting techniques that detect seismic anisotropy and the pattern of mantle deformation. The along strike change in slab dip angle and buoyancy content is found to exert a strong control over the surrounding mantle flow field. Modeling of the induced mantle flow, and the dynamic topography at the surface that results, predicts a wave of dynamic subsidence that propagates away from the trench as the flat slab develops. This is found to correlate well with the record of widespread sediment deposition across western Amazonia during the Miocene. A combination of uplift, flexure and dynamic topography during slab flattening is proposed to explain the overall landscape evolution of the region and the subsequent configuration of the transcontinental Amazon drainage system we see today.

  13. Subduction and volatile recycling in Earth's mantle

    NASA Technical Reports Server (NTRS)

    King, S. D.; Ita, J. J.; Staudigel, H.

    1994-01-01

    The subduction of water and other volatiles into the mantle from oceanic sediments and altered oceanic crust is the major source of volatile recycling in the mantle. Until now, the geotherms that have been used to estimate the amount of volatiles that are recycled at subduction zones have been produced using the hypothesis that the slab is rigid and undergoes no internal deformation. On the other hand, most fluid dynamical mantle flow calculations assume that the slab has no greater strength than the surrounding mantle. Both of these views are inconsistent with laboratory work on the deformation of mantle minerals at high pressures. We consider the effects of the strength of the slab using two-dimensional calculations of a slab-like thermal downwelling with an endothermic phase change. Because the rheology and composition of subducting slabs are uncertain, we consider a range of Clapeyron slopes which bound current laboratory estimates of the spinel to perovskite plus magnesiowustite phase transition and simple temperature-dependent rheologies based on an Arrhenius law diffusion mechanism. In uniform viscosity convection models, subducted material piles up above the phase change until the pile becomes gravitationally unstable and sinks into the lower mantle (the avalanche). Strong slabs moderate the 'catastrophic' effects of the instabilities seen in many constant-viscosity convection calculations; however, even in the strongest slabs we consider, there is some retardation of the slab descent due to the presence of the phase change.

  14. A quantitative study of ramped radio frequency, magnetization transfer, and slab thickness in three-dimensional time-of-flight magnetic resonance angiography in a patient population.

    PubMed

    Goodrich, K C; Blatter, D D; Parker, D L; Du, Y P; Meyer, K J; Bernstein, M A

    1996-06-01

    The authors compare the effectiveness of various magnetic resonance (MR) angiography acquisition strategies in enhancing the visibility of small intracranial vessels. Blood vessel contrast-to-noise ratio (CNR) in time-of-flight MR angiography was studied as a function of vessel size and several selectable imaging parameters. Contrast-to-noise measurements were made on 257 vessel segments ranging in size from 0.3 mm to 4.2 mm in patients who recently had undergone intraarterial cerebral angiography. Imaging parameters studied included magnetization transfer, spatially variable radio frequency (RF) pulse profile (ramped RF), and imaging slab thickness. The combination of thin slabs (16 slices/slab), ramped RF, and magnetization transfer resulted in the highest CNR for all but the smallest vessel sizes. The smallest vessels (< 0.5 mm) had the highest CNR, using the thick slab (64 slices/slab) with ramped RF and magnetization transfer. Magnetization transfer always improved vessel CNR, but the improvement diminished as the slab thickness was reduced. The CNR increased with a decrease in slab thickness for all but the smallest vessel sizes. Overall, the results provide a quantitative demonstration that inflow enhancement of blood is reduced for small vessels. Thus, whereas magnetization transfer is important at all vessel sizes, it becomes the primary factor in improving the visibility of the smallest vessels.

  15. Quantum confinement effects on electronic photomobilities at nanostructured semiconductor surfaces: Si(111) without and with adsorbed Ag clusters

    NASA Astrophysics Data System (ADS)

    Hembree, Robert H.; Vazhappilly, Tijo; Micha, David A.

    2017-12-01

    The conductivity of holes and electrons photoexcited in Si slabs is affected by the slab thickness and by adsorbates. The mobilities of those charged carriers depend on how many layers compose the slab, and this has important scientific and technical consequences for the understanding of photovoltaic materials. A previously developed general computational procedure combining density matrix and electronic band structure treatments has been applied to extensive calculations of mobilities of photoexcited electrons and holes at Si(111) nanostructured surfaces with varying slab thickness and for varying photon energies, to investigate the expected change in mobility magnitudes as the slab thickness is increased. Results have been obtained with and without adsorbed silver clusters for comparison of their optical and photovoltaic properties. Band states were generated using a modified ab initio density functional treatment with the PBE exchange and correlation density functionals and with periodic boundary conditions for large atomic supercells. An energy gap correction was applied to the unoccupied orbital energies of each band structure by running more accurate HSE hybrid functional calculations for a Si(111) slab. Photoexcited state populations for slabs with 6, 8, 10, and 12 layers were generated using a steady state reduced density matrix including dissipative effects due to energy exchange with excitons and phonons in the medium. Mobilities have been calculated from the derivatives of voltage-driven electronic energies with respect to electronic momentum, for each energy band and for the average over bands. Results show two clear trends: (a) adding Ag increases the hole photomobilities and (b) decreasing the slab thickness increases hole photomobilities. The increased hole populations in 6- and 8-layer systems and the large increase in hole mobility for these thinner slabs can be interpreted as a quantum confinement effect of hole orbitals. As the slab thickness increases to ten and twelve layers, the effect of silver adsorbates decreases leading to smaller relative enhancements to the conduction electron and hole mobilities, but the addition of the silver nanoclusters still increases the absorbance of light and the mobility of holes compared to their mobilities in the pure Si slabs.

  16. Numerical simulations of water transport in subduction zone: Influences of serpentinized layer in oceanic slabs on subduction dynamics

    NASA Astrophysics Data System (ADS)

    Nakao, A.; Hikaru, I.; Nakakuki, T.; Suzuki, Y.; Nakamura, H.

    2017-12-01

    Water liberated from subducting oceanic slabs can affect the subduction dynamics such as mantle wedge flows and plate motion (e.g., Gerya & Meilick, 2011; Horiuchi & Iwamori, 2016; Nakao et al., 2016). However, how water liberated from the slabs, in particular a hydrated part within the oceanic lithosphere (e.g., Fujie et al., 2013), is transported and affects the subduction dynamics has not been fully understood. In order to clarify the roles of water in subduction dynamics, we conducted 2-D dynamical simulations of water transport and mantle convection without imposing the geometry and velocity of subducting slabs. Using the simulations with various thicknesses (0-20 km) of a partially serpentinized layer (hereafter referred to as "SL") underlaying the altered oceanic basalt crust (AOC) in the subducting oceanic lithosphere, we estimate the subduction rate, back-arc spreading, trench migration, and slab geometry. The simulations show that the plate motion significantly changes depending on the amount of liberated water. When the SL is absent (0 km thick), the AOC mostly dehydrates at shallow depths (< 70 km). In this case, the plate subducts slowly, the trench is stationary, and the slab penetrates the 660-km boundary. If the SL is 7.5 km in thickness, it dehydrates at a greater depth compared to AOC, and more water enters the mantle wedge and the back-arc region. The liberated water reduces the viscosity of mantle wedge, and consequently, the subduction rate increases, the trench migrates seaward, and the slab stagnates on the 660-km. If the SL is 20 km in thickness, the upper SL releases much water into the mantle wedge and the back-arc region, whereas the lower SL does not dehydrate because of water uptake by phase A and phase D. In this case, because buoyancy of the subducting slab increases, the subduction is slow, back-arc spreading is weakened, and the slab penetrates the 660-km. Our results imply that the observed variety of subducting slabs reflects different amounts of water liberated from and within the slabs.

  17. Using the MDCT thick slab MinIP method for the follow-up of pulmonary emphysema.

    PubMed

    Lan, Hai; Nishitani, Hiromu; Nishihara, Sadamitsu; Ueno, Junji; Takao, Shoichiro; Iwamoto, Seiji; Kawanaka, Takashi; Mahmut, Mawlan; Qingge, Si

    2011-08-01

    The purpose of this study was to evaluate the usefulness of thick slab minimum intensity projection (MinIP) as a follow-up method in patients with pulmonary emphysema. This method was used to determine the presence or absence of changes over time in the lung field based on multi-detector-row CT (MDCT) data. Among patients diagnosed with pulmonary emphysema who underwent 16-MDCT (slice thickness, 1 mm) twice at an interval of 6 months or more, 12 patients without changes in the lung field and 14 with clear changes in the lung field were selected as subjects. An image interpretation experiment was performed by five image interpreters. Pulmonary emphysema was followed up using two types of thick slab MinIP (thick slab MinIP 1 and 2) and multi-planar reformation (MPR), and the results of image interpretation were evaluated by receiver operating characteristic (ROC) analysis. In addition, the time required for image interpretation was compared among the three follow-up methods. The area under the ROC curve (Az) was 0.794 for thick slab MinIP 1, 0.778 for the thick slab MinIP 2, and 0.759 for MPR, showing no significant differences among the three methods. Individual differences in each item were significantly more marked for MPR than for thick slab MinIP. The time required for image interpretation was around 18 seconds for thick slab MinIP 1, 11 seconds for thick slab MinIP 2, and approximately 127 seconds for MPR, showing significant differences among the three methods. There were no significant differences in the results of image interpretation regarding the presence or absence of changes in the lung fields between thick slab MinIP and MPR. However, thick slab MinIP showed a shorter image interpretation time and smaller individual differences in the results among image interpreters than MPR, suggesting the usefulness of this method for determining the presence or absence of changes with time in the lung fields of patients with pulmonary emphysema.

  18. Investigation of approach slab and its settlement for roads and bridges.

    DOT National Transportation Integrated Search

    2014-01-01

    Approach slabs serve as a transitional system between an approach road and a bridge. Settlement of bridge approach slabs and their : supporting backfill has been experienced by more than ten Departments of Transportation throughout the United States....

  19. Precast concrete replacement slabs for bridge decks.

    DOT National Transportation Integrated Search

    1982-01-01

    The report illustrates and evaluates the first use in Virginia of precast concrete replacement slabs for bridge decks. It shows that a bridge deck can be replaced with the precast slabs while traffic is maintained in the adjacent traffic lane. The qu...

  20. On reducing bumps at pavement-bridge interface.

    DOT National Transportation Integrated Search

    2010-12-21

    This report contains the causes and long-term solutions to the bumps at bridge/approach slab and/or approach slab/pavement interface. A research was conducted on both structural and geotechnical aspects of an approach slab. : A 3-D finite element ana...

  1. Bulldozing of Basal Continental Mantle Lithosphere During Flat-Slab Subduction

    NASA Astrophysics Data System (ADS)

    Axen, G. J.; van Wijk, J.; Currie, C. A.

    2017-12-01

    Flat-slab subduction occurs along 10% of subduction margins, forming magmatic gaps and causing inland migration of upper-plate deformation. We suggest that basal continental mantle lithosphere (CML) can be bulldozed ahead of the flat portion of horizontally-subducted oceanic lithosphere, forming a growing and advancing keel of thickened CML. This process fills the asthenospheric mantle wedge with CML, precluding melting. The bulldozed CML keel may transmit tectonic stresses ahead of the flat slab itself, causing upper-plate deformation ahead of the slab hinge. We designed 2-D numerical models after the North American Laramide orogeny, with subduction of a thick, buoyant oceanic plateau (conjugate Shatsky Rise) and with the continent advancing trenchward over the initial slab hinge. This results in slab-flattening, and removal of CML material. In our models, the thickness of the CML layer removed by this process depends on overriding plate rheology and is up to 25 km. The removed material is bulldozed ahead of the hinge and may fill up the asthenospheric wedge. Low-density (depleted) CML favors formation of bulldozed keels, which increase in width as CML strength decreases. Regular-density and/or stronger CML forms smaller bulldozed keels that are more likely to sink with the slab as eclogitization and densification proceed. When the flat slab rolls back, it leaves a step in the CML at the farthest extent of the slab. Relics of this step may remain below North America or may have dripped off. We interpret an upper-mantle fast-velocity anomaly below SE New Mexico and W Texas as a drip/keel, and the step in lithosphere thickness in southwestern Colorado as a fossil step, caused by the removal of the CML layer. Our model predicts that the Laramide bulldozed CML keel may have aided in stress transmission that caused basement uplifts as far as NE Wyoming and subsurface folds even farther N and E. Modern examples may exist in South American flat slab segments.

  2. Regional body wave tomography of the Peruvian flat slab

    NASA Astrophysics Data System (ADS)

    Young, B. E.; Wagner, L. S.; Knezevic Antonijevic, S.; Kumar, A.; Beck, S. L.; Long, M. D.; Tavera, H.

    2013-12-01

    Local travel time data from the PerU Lithosphere and Slab Experiment (PULSE) were used to create three dimensional tomographic models of Vp and Vs above the flat slab in southern Peru. In the flat slab subduction regions of Peru and central Chile/Argentina, the Nazca plate subducts normally to a depth of ~100 km and then bends and progresses subhorizontally for several hundreds of kilometers before it resumes steep subduction. The Peruvian flat slab segment, located between 3°S and 15°S, corresponds to a gap in the volcanic arc and far-field thick-skinned deformation in the Eastern Cordillera. Despite ongoing research, there is still little consensus on the causes and consequences of flat slab subduction. In western North American, it has been suggested that flat subduction may have been responsible for the formation of the Rocky Mountains and ignimbrite flare-up during the Laramide orogeny. Preliminary tomography results show high shear wave velocities above the slab for a region that coincides with the location of the Nazca ridge, a 200 km wide bathymetric high that is currently subducting at ~15°S. Meanwhile, P wave velocities appear to be relatively normal. North of the ridge location, shear wave velocities can be separated into sublinear high (near the coast) and low (inland) velocity zones oriented approximately parallel to the trench. This geometry corresponds well with the organization of geotectonic and morphological terrains in Peru. High shear wave velocities above the slab are consistent with results from the 2000-2002 CHARGE deployment in central Chile/Argentina. This could indicate the presence of silica enriched, dry continental lithosphere, or it may be due to the presence of an anisotropic layer of hydrous phases directly above the slab. Future comparisons with results from Rayleigh wave tomography aim to address the role of anisotropy in observed shear wave velocities above flat slabs.

  3. Thermal Lens Measurement in Diode-Pumped Nd:YAG Zig-Zag Slab

    NASA Technical Reports Server (NTRS)

    Smoak, M. C.; Kay, R. B.; Coyle, D. B.; Hopf, D.

    1998-01-01

    A major advantage that solid state zig-zag slab lasers have over conventional rod-based designs is that a much weaker thermal lens is produced in the slab when side-pumped with Quasi-CW laser diode arrays, particularly if the pump radiation is kept well away from the Brewster-cut ends. This paper reports on a rather strong thermal lens produced when diode pump radiation is collimated into a narrow portion of the zig-zag slab. The collimation of multi-bar pump packages to increase brightness and improve overlap is a direct consequence of designs which seek to maximize performance and efficiency. Our slab design employed a 8.1 cm x 2.5 mm x 5 mm slab with opposing Brewster end faces. It was pumped through the 2.5 mm direction by seven laser diode array packages, each housing four 6OW diode bars, 1 cm in width. The pump face, anti-reflection (AR) coated at 809 nm, was 6.8 cm in width and the 8.1 cm opposing side, high-reflection (HR) coated at 809 nm, reflected the unabsorbed pump beam for a second pass through the slab.

  4. Eelgrass slabs, a soilless culture substrate that inhibits adhesion of fungi and oomycetes and enhances antioxidant activity in tomato.

    PubMed

    Meot-Duros, Laetitia; Le Floch, Gaëtan; Meot, Benoit; Letousey, Patricia; Jacob, Bruno; Barbier, Georges

    2011-10-26

    Composed of a marine plant, Zostera sp., eelgrass slabs are a novel organic substrate for soilless cultures used in tomato production. The benefit of using eelgrass slabs for growing tomatoes was assessed by comparing it with coconut fiber slabs in regard to contamination by Pythium spp. and to the antioxidant properties of tomato fruits. First, tomato root contamination by Pythium spp. was studied by direct plate counting, and a molecular comparison of fungal and oomycete communities was conducted using PCR-DHPLC. Second, the antioxidant properties of tomato fruits were analyzed by measuring total phenol and carotenoid contents and by evaluating radical scavenging activity. Compared to plants grown on coconut fiber slabs, those on eelgrass slabs presented a lower rate of Pythium spp. root contamination. Moreover, culture on eelgrass slabs produced fruits with better radical scavenging activity and higher total phenol content compared to controls. Carotenoid content was not affected by the type of substrate. This study highlights the value of detrital leaves of Zostera sp. as a substrate for soilless culture that reduces root contamination and also promotes the production of tomato fruits with better nutritional value.

  5. Slab dragging and the recent geodynamic evolution of the western Mediterranean plate boundary region

    NASA Astrophysics Data System (ADS)

    Spakman, Wim; Chertova, Maria V.; van den Berg, Arie P.; Thieulot, Cedric; van Hinsbergen, Douwe J. J.

    2016-04-01

    The Tortonian-Present geodynamic evolution of the plate boundary between North Africa and Iberia is characterized by first-order enigmas. This concerns, e.g., the diffuse tectonic activity of the plate boundary; the crustal thickening below the Rif; the closing of the northern Moroccan marine gateways prior to the Messinian Salinity Crisis; crustal extension of the central to eastern Betics; the origin and sense of motion of the large left-lateral Trans Alboran Shear Zone (TASZ) and Eastern Betic Shear Zone (EBSZ); and lithosphere delamination of the North African continental edge. Many explanations have been given for each of these seemingly disparate tectonic features, which invariably have been addressed in the plate tectonic context of the NW-SE relative plate convergence between the major plates since the Tortonian, mostly independently from each other. Usually there is no clear role for the subducted slab underlying the region, except for presumed rollback, either to SW or to the W, depending on the type of observations that require explanation. Here we integrate the dynamic role of the slab with the NW-SE relative plate convergence by 3-D numerical modelling of the slab evolution constrained by absolute plate motions (Chertova et al., JGR,2014 & Gcubed 2014). By combining observations and predictions from seismology, geology, and geodesy, with our numerical 3-D slab-mantle dynamics modelling, we developed a new and promising geodynamic framework that provides explanations of all noted tectonic enigmas in a coherent and connected way. From the Tortonian until today, we propose that mantle-resisted slab dragging combines with the NW-SE plate convergence across the (largely) unbroken plate boundary to drive the crustal deformation of the region. Slab dragging is the lateral transport, pushing or pulling, of slab through the mantle by the absolute motion of the subducting plate (Chertova et al., Gcubed, 2014). Because the slab is connected to both the Iberian and African lithosphere, both plates are dragging the slab by their shared ~NNE component of absolute plate motion, which in fact is invisible in the relative plate convergence frame that is usually adopted. Slab dragging induces mantle resistance that, we demonstrate by numerical modelling, leads in the region to differential lateral motion between the slab and African plate driving indentation of the Africa continental lithosphere leading to crustal shortening explaining the closure of Moroccan seaways and the thickening of the Rif crust. The differential motion also explains the TASZ and the transition from western Betics shortening to eastern Betics extension, both still active today. During Miocene westward slab rollback mantle-resisted slab dragging also provided the driving force of edge delamination of African lithosphere, we propose. These explanations of geological features are fully corroborates by an analysis of the GPS motion field in terms of the strain- and rotation rate fields using the method of Spakman and Nyst (2002), and the predicted crustal flow field. In particular, we derive from the GPS and geological data that the direction of African absolute motion is ~NNE and that the slab experiences at present negligible rollback.

  6. Development Length for Headed Bars in Slab-Column Joints of RC Slab Bridges

    DOT National Transportation Integrated Search

    2015-12-04

    In accordance with the Caltrans Seismic Design Criteria, the superstructure in a slab bridge should remain essentially elastic and only the pile extensions/columns are permitted to develop inelastic deformations during a seismic event. Hence, the lon...

  7. Polymer-impregnated bridge slabs : performance over 10 years.

    DOT National Transportation Integrated Search

    1990-01-01

    This report presents the results of a study to evaluate the performance over a 10-year period of slabs that were impregnated to a depth of about 1 in with a monomer that was subsequently polymerized (shallow polymer impregnation). The slabs were used...

  8. Determination of interaction between bridge concrete approach slab and embankment settlement.

    DOT National Transportation Integrated Search

    2005-07-01

    The main objective of this research is to correlate the deformation and internal force of the approach slab with the approach embankment settlements and the approach slab parameters such as length and thickness. Finite element analysis was carried ou...

  9. Precast alternative for flat slab bridges : final report.

    DOT National Transportation Integrated Search

    2013-10-26

    The cast-in-place (CIP) concrete slab bridge and the hollow core flat slab bridge are two very common bridge types utilized by the : South Carolina Department of Transportation (SCDOT). The CIP bridge is durable but has a long construction time while...

  10. Dynamic Eigenvalue Problem of Concrete Slab Road Surface

    NASA Astrophysics Data System (ADS)

    Pawlak, Urszula; Szczecina, Michał

    2017-10-01

    The paper presents an analysis of the dynamic eigenvalue problem of concrete slab road surface. A sample concrete slab was modelled using Autodesk Robot Structural Analysis software and calculated with Finite Element Method. The slab was set on a one-parameter elastic subsoil, for which the modulus of elasticity was separately calculated. The eigen frequencies and eigenvectors (as maximal vertical nodal displacements) were presented. On the basis of the results of calculations, some basic recommendations for designers of concrete road surfaces were offered.

  11. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, Peter J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  12. Slab2 - Updated Subduction Zone Geometries and Modeling Tools

    NASA Astrophysics Data System (ADS)

    Moore, G.; Hayes, G. P.; Portner, D. E.; Furtney, M.; Flamme, H. E.; Hearne, M. G.

    2017-12-01

    The U.S. Geological Survey database of global subduction zone geometries (Slab1.0), is a highly utilized dataset that has been applied to a wide range of geophysical problems. In 2017, these models have been improved and expanded upon as part of the Slab2 modeling effort. With a new data driven approach that can be applied to a broader range of tectonic settings and geophysical data sets, we have generated a model set that will serve as a more comprehensive, reliable, and reproducible resource for three-dimensional slab geometries at all of the world's convergent margins. The newly developed framework of Slab2 is guided by: (1) a large integrated dataset, consisting of a variety of geophysical sources (e.g., earthquake hypocenters, moment tensors, active-source seismic survey images of the shallow slab, tomography models, receiver functions, bathymetry, trench ages, and sediment thickness information); (2) a dynamic filtering scheme aimed at constraining incorporated seismicity to only slab related events; (3) a 3-D data interpolation approach which captures both high resolution shallow geometries and instances of slab rollback and overlap at depth; and (4) an algorithm which incorporates uncertainties of contributing datasets to identify the most probable surface depth over the extent of each subduction zone. Further layers will also be added to the base geometry dataset, such as historic moment release, earthquake tectonic providence, and interface coupling. Along with access to several queryable data formats, all components have been wrapped into an open source library in Python, such that suites of updated models can be released as further data becomes available. This presentation will discuss the extent of Slab2 development, as well as the current availability of the model and modeling tools.

  13. Visualizing Three-dimensional Slab Geometries with ShowEarthModel

    NASA Astrophysics Data System (ADS)

    Chang, B.; Jadamec, M. A.; Fischer, K. M.; Kreylos, O.; Yikilmaz, M. B.

    2017-12-01

    Seismic data that characterize the morphology of modern subducted slabs on Earth suggest that a two-dimensional paradigm is no longer adequate to describe the subduction process. Here we demonstrate the effect of data exploration of three-dimensional (3D) global slab geometries with the open source program ShowEarthModel. ShowEarthModel was designed specifically to support data exploration, by focusing on interactivity and real-time response using the Vrui toolkit. Sixteen movies are presented that explore the 3D complexity of modern subduction zones on Earth. The first movie provides a guided tour through the Earth's major subduction zones, comparing the global slab geometry data sets of Gudmundsson and Sambridge (1998), Syracuse and Abers (2006), and Hayes et al. (2012). Fifteen regional movies explore the individual subduction zones and regions intersecting slabs, using the Hayes et al. (2012) slab geometry models where available and the Engdahl and Villasenor (2002) global earthquake data set. Viewing the subduction zones in this way provides an improved conceptualization of the 3D morphology within a given subduction zone as well as the 3D spatial relations between the intersecting slabs. This approach provides a powerful tool for rendering earth properties and broadening capabilities in both Earth Science research and education by allowing for whole earth visualization. The 3D characterization of global slab geometries is placed in the context of 3D slab-driven mantle flow and observations of shear wave splitting in subduction zones. These visualizations contribute to the paradigm shift from a 2D to 3D subduction framework by facilitating the conceptualization of the modern subduction system on Earth in 3D space.

  14. MAGNETIC FIELD LINE RANDOM WALK FOR DISTURBED FLUX SURFACES: TRAPPING EFFECTS AND MULTIPLE ROUTES TO BOHM DIFFUSION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ghilea, M. C.; Ruffolo, D.; Sonsrettee, W.

    2011-11-01

    The magnetic field line random walk (FLRW) is important for the transport of energetic particles in many astrophysical situations. While all authors agree on the quasilinear diffusion of field lines for fluctuations that mainly vary parallel to a large-scale field, for the opposite case of fluctuations that mainly vary in the perpendicular directions, there has been an apparent conflict between concepts of Bohm diffusion and percolation/trapping effects. Here computer simulation and non-perturbative analytic techniques are used to re-examine the FLRW in magnetic turbulence with slab and two-dimensional (2D) components, in which 2D flux surfaces are disturbed by the slab fluctuations.more » Previous non-perturbative theories for D{sub perpendicular}, based on Corrsin's hypothesis, have identified a slab contribution with quasilinear behavior and a 2D contribution due to Bohm diffusion with diffusive decorrelation (DD), combined in a quadratic formula. Here we present analytic theories for other routes to Bohm diffusion, with random ballistic decorrelation (RBD) either due to the 2D component itself (for a weak slab contribution) or the total fluctuation field (for a strong slab contribution), combined in a direct sum with the slab contribution. Computer simulations confirm the applicability of RBD routes for weak or strong slab contributions, while the DD route applies for a moderate slab contribution. For a very low slab contribution, interesting trapping effects are found, including a depressed diffusion coefficient and subdiffusive behavior. Thus quasilinear, Bohm, and trapping behaviors are all found in the same system, together with an overall viewpoint to explain these behaviors.« less

  15. Plate tectonic reconstruction of South and East Asia since 43 Ma using seismic tomographic constraints: role of the subducted ';East Asia Sea' (Invited)

    NASA Astrophysics Data System (ADS)

    Wu, J. E.; Suppe, J.; Renqi, L.; Kanda, R. V.

    2013-12-01

    Lithosphere that subducts at convergent plate boundaries provides a potentially decipherable plate tectonic record. In this study we use global seismic tomography to map subducted slabs in the upper and lower mantle under South and East Asia to constrain plate reconstructions. The mapped slabs include the Pacific, the Indian Ocean and Banda Sea, the Molucca Sea, Celebes Sea, the Philippine Sea and Eurasia, New Guinea and other lower mantle detached slabs. The mapped slabs were restored to the earth surface and used with Gplates software to constrain a globally-consistent, fully animated plate reconstruction of South and East Asia. Three principal slab elements dominate possible plate reconstructions: [1] The mapped Pacific slabs near the Izu-Bonin and the Marianas trenches form a subvertical slab curtain or wall extending down to 1500 km in the lower mantle. The ';slab curtain' geometry and restored slabs lengths indicate that the Pacific subduction zone has remained fixed within +/- 250 km of its present position since ~43 Ma. In contrast, the Tonga Pacific slab curtain records at least 1000 km trench rollback associated with expansion of back-arc basins. [2] West of the Pacific slab curtain, a set of flat slabs exist in the lower mantle and record a major 8000km by 2500-3000km ocean that existed at ~43 Ma. This now-subducted ocean, which we call the ';East Asian Sea', existed between the Ryukyu Asian margin and the Lord Howe hotspot, present-day eastern Australia, and fills a major gap in Cenozoic plate reconstructions between Indo-Australia, the Pacific Ocean and Asia. [3] An observed ';picture puzzle' fit between the restored edges of the Philippine Sea, Molucca Sea and Indian Ocean slabs suggests that the Philippine Sea was once part of a larger Indo-Australian Ocean. Previous models of Philippine Sea plate motions are in conflict with the location of the East Asian Sea lithosphere. Using the mapped slab constraints, we propose the following 43 Ma to 0 plate tectonic reconstruction. At ~43 Ma a major plate reorganization occurred in South and East Asia marked by Indian Ocean Wharton ridge extinction, initiation of Pacific Ocean WNW motions and the rapid northward motion of the Australian plate. The Philippine Sea and Molucca Sea were clustered at the northern margin of Australia, northwest of New Guinea. During the mid-Cenozoic these plates moved NNE with Australia, accommodated by N-S transforms at the eastern margin of Sundaland. The East Asian Sea was subducted under the northward-moving Philippine Sea and Australia plates, and the expanding Melanesian and Shikoku-Parece Vela backarc basins. At ~20 to 25 Ma the Philippine Sea and Molucca Sea were fragmented from Indo-Australia and began to have a westward component of motion due to partial Pacific capture. Around 1-2 Ma the Philippine Sea was more fully captured by the Pacific and now has rapid Pacific-like northwestward motions.

  16. Experimental study of a VBG-based Tm : YLF slab laser at different output coupler parameters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duan, X M; Ding, Y; Dai, T Y

    2015-04-30

    The performance of a Tm : YLF slab laser is studied at different output coupler parameters. Use is made of a 20-mm-long a-cut slab crystal doped with 2.5 at. % thulium ions. With a volume Bragg grating and a Fabry – Perot etalon, the selected output wavelength of this Tm : YLF slab laser is 1908 nm. For the optimised output coupler with a transmission of 20% and a radius of curvature of 300 mm, the output power exceeds 74.1 W and the slope efficiency with respect to the absorbed pump power reaches 48.4%. In addition, the beam quality ofmore » the Tm : YLF slab laser is improved. (lasers)« less

  17. General analysis of slab lasers using geometrical optics.

    PubMed

    Chung, Te-yuan; Bass, Michael

    2007-02-01

    A thorough and general geometrical optics analysis of a slab-shaped laser gain medium is presented. The length and thickness ratio is critical if one is to achieve the maximum utilization of absorbed pump power by the laser light in such a medium; e.g., the fill factor inside the slab is to be maximized. We point out that the conditions for a fill factor equal to 1, laser light entering and exiting parallel to the length of the slab, and Brewster angle incidence on the entrance and exit faces cannot all be satisfied at the same time. Deformed slabs are also studied. Deformation along the width direction of the largest surfaces is shown to significantly reduce the fill factor that is possible.

  18. Accelerated slab replacement using temporary precast panels and self-consolidating concrete.

    DOT National Transportation Integrated Search

    2016-06-06

    Slab replacement is the main activity in any concrete pavement rehabilitation project. According to a survey of industry and FDOT, contractor productivity in slab replacements has been very low, ranging between 25 to 50 cu. yds. The low number of sla...

  19. Studies on Punching Shear Resistance of Two Way Slab Specimens with Partial Replacement of Cement by GGBS with Different Edge Conditions

    NASA Astrophysics Data System (ADS)

    Nemani, Ravi Dakshina Murthy; Rao, M. V. S.; Grandhe, Veera Venkata Satya Naranyana

    2016-09-01

    The present work is an effort to quantify the punching shear load resistance effect on two way simply supported slab specimens with replacement of cement by Ground Granulated Blast Furnace Slag (GGBS) with different edge conditions at various replacement levels and evaluate its efficiency. GGBS replacement has emerged as a major alternative to conventional concrete and has rapidly drawn the concrete industry attention due to its cement savings, cost savings, environmental and socio-economic benefits. The two way slab specimens were subjected to punching shear load by in house fabricated apparatus. The slab specimens were cast using M30 grade concrete with HYSD bars. The cement was partially replaced with GGBS at different percentages i.e., 0 to 30 % at regular intervals of 10 %. The test results indicate that the two way slab specimens with partial replacement of cement by GGBS exhibit high resistance against punching shear when compared with conventional concretes slab specimens.

  20. Farallon slab detachment and deformation of the Magdalena Shelf, southern Baja California

    USGS Publications Warehouse

    Brothers, Daniel S.; Harding, Alistair J.; Gonzalez-Fernandez, Antonio; Holbrook, W.S. Steven; Kent, Graham M.; Driscoll, Neal W.; Fletcher, John M.; Lizarralde, Daniel; Umhoefer, Paul J.; Axen, Gary

    2012-01-01

    Subduction of the Farallon plate beneath northwestern Mexico stalled by ~12 Ma when the Pacific-Farallon spreading-ridge approached the subduction zone. Coupling between remnant slab and the overriding North American plate played an important role in the capture of the Baja California (BC) microplate by the Pacific Plate. Active-source seismic reflection and wide-angle seismic refraction profiles across southwestern BC (~24.5°N) are used to image the extent of remnant slab and study its impact on the overriding plate. We infer that the hot, buoyant slab detached ~40 km landward of the fossil trench. Isostatic rebound following slab detachment uplifted the margin and exposed the Magdalena Shelf to wave-base erosion. Subsequent cooling, subsidence and transtensional opening along the shelf (starting ~8 Ma) starved the fossil trench of terrigenous sediment input. Slab detachment and the resultant rebound of the margin provide a mechanism for rapid uplift and exhumation of forearc subduction complexes.

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