WorldWideScience

Sample records for grounding zone wedges

  1. Ground penetrating radar estimates of permafrost ice wedge depth

    Science.gov (United States)

    Parsekian, A.; Slater, L. D.; Nolan, J. T.; Grosse, G.; Walter Anthony, K. M.

    2013-12-01

    Vertical ground ice wedges associated with polygonal patterning in permafrost environments form due to frost cracking of soils under harsh winter conditions and subsequent infilling of cracks with snow melt water. Ice wedge polygon patterns have implications for lowland geomorphology, hydrology, and vulnerability of permafrost to thaw. Ice wedge dimensions may exceed two meters width at the surface and several meters depth, however few studies have addressed the question of ice wedge depth due to challenges related to measuring the vertical dimension below the ground. Vertical exposures where ice wedges maybe observed are limited to rapidly retreating lake, river, and coastal bluffs. Coring though the ice wedges to determine vertical extent is possible, however that approach is time consuming and labor intensive. Many geophysical investigations have noted signal anomalies related to the presence of ice wedges, but no reliable method for extracting wedge dimensions from geophysical data has been yet proposed. Here we present new evidence that ground penetrating radar (GPR) may be a viable method for estimating ice wedge depth. We present three new perspectives on processing GPR data collected over ice wedges that show considerable promise for use as a fast, cost effective method for evaluating ice wedge depth. Our novel approaches include 1) a simple frequency-domain analysis, 2) an S-transform frequency domain analysis and 3) an analysis of the returned signal power as a radar cross section (RCS) treating subsurface ice wedges as dihedral corner retro-reflectors. Our methods are demonstrated and validated using finite-difference time domain FDTD) GPR forward models of synthetic idealized ice wedges and field data from permafrost sites in Alaska. Our results indicate that frequency domain and signal power data provide information that is easier to extract from raw GPR data than similar information in the time domain. We also show that we can simplify the problem by

  2. Structural control of the Gagua "Wedge" Zone east of Taiwan Island on the southern Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yanpeng; LIU Baohua; WU Jinlong; LIANG Ruicai; LIU Chenguang; ZHANG Zhengmin

    2005-01-01

    Based on compositive analysis and interpretation of the observed and historical data, the geophysical field characters and structural properties of the Gagua "Wedge" Zone of the sea area east of Taiwan Island and the primary tectonic stress direction and its variabilities of backarc spreading in the southern Okinawa Trough are studied. It is concluded from the study results that the Gagua "Wedge" Zone is structurally consistent with the Gagua ridge and two fault basins on both sides of the Gagua ridge, and adjusts the moving direction and distance of the western Philippine Sea plate to make the northwestward motion of the plate on its east side change to the northward subduction of the plate on its west side so that the primary tectonic stress direction of the Okinawa Trough changed from NW-SE to nearly N-S, which provided the stress source for the Okinawa Trough to enter the second spreading stage.

  3. Fresnel zones for ground-based antennas

    DEFF Research Database (Denmark)

    Andersen, J. Bach

    1964-01-01

    The ordinary Fresnel zone concept is modified to include the influence of finite ground conductivity. This is important for ground-based antennas because the influence on the radiation pattern of irregularities near the antenna is determined by the amplitude and phase of the groundwave. A new...

  4. Numerical modeling of mantle wedge processes and exhumation of UHP mantle in subduction zones

    Science.gov (United States)

    Gorczyk, W.; Gerya, T. V.; Guillot, S.; Connolly, J. A.; Yuen, D.

    2007-12-01

    The upwelling of subduction generated partially molten rocks is potentially a mechanism for the exhumation of UHP rocks through the mantle wedge. We investigated this processes using a 2-D coupled petrological- thermomechanical model that incorporates slab dehydration and water transport as well as partial melting of mantle and crustal rocks. This approach allows us to study the dynamics of mantle wedge processes including evolution of partially molten plumes and their interaction with surrounding dry mantle. To study the internal structure of the plumes we used ultra-high resolution numerical simulations with 10 billion active markers to detail the internal structure of natural plumes originating from the slab. The plumes consist of partially molten hydrated peridotite, dry solid mantle and subducted oceanic crust, which may comprise up to 12 volume % of the plume. As the plumes grow and mature these materials mix chaotically resulting in attenuation and duplication of the original layering on scales of 1-1000 m. Comparison of numerical results with geological observations from the Horoman ultramafic complex in Japan suggests that mixing and differentiation processes related to development of partially molten plumes above slabs may be responsible for strongly layered lithologically mixed (marble cake) structure of asthenospheric mantle wedges. The recent discovery of garnet bearing peridotites in the subduction zone of the Great Antilles in Hispaniola has raised questions about the process that leads to their exhumation. To evaluate whether upwelling plumes are a plausible exhumation mechanism we investigated the dynamics of subduction of slow spreading ridges. The results show that subduction of strongly serpentinized oceanic plate causes strong dehydration of the slab and leads to a rheological weakening of the interface between subducting and overriding plate. This weakening triggers trench retreat and massive asthenospheric upwelling into the gap between the

  5. Seismic evidence for flow in the hydrated mantle wedge of the Ryukyu subduction zone

    Science.gov (United States)

    Nagaya, Takayoshi; Walker, Andrew M.; Wookey, James; Wallis, Simon R.; Ishii, Kazuhiko; Kendall, J.-Michael

    2016-07-01

    It is widely accepted that water-rich serpentinite domains are commonly present in the mantle above shallow subducting slabs and play key roles in controlling the geochemical cycling and physical properties of subduction zones. Thermal and petrological models show the dominant serpentine mineral is antigorite. However, there is no good consensus on the amount, distribution and alignment of this mineral. Seismic velocities are commonly used to identify antigorite-rich domains, but antigorite is highly-anisotropic and depending on the seismic ray path, its properties can be very difficult to distinguish from non-hydrated olivine-rich mantle. Here, we utilize this anisotropy and show how an analysis of seismic anisotropy that incorporates measured ray path geometries in the Ryukyu arc can constrain the distribution, orientation and amount of antigorite. We find more than 54% of the wedge must consist of antigorite and the alignment must change from vertically aligned to parallel to the slab. This orientation change suggests convective flow in the hydrated forearc mantle. Shear wave splitting analysis in other subduction zones indicates large-scale serpentinization and forearc mantle convection are likely to be more widespread than generally recognized. The view that the forearc mantle of cold subduction zones is dry needs to be reassessed.

  6. Inside the subduction factory: Modeling fluid mobile element enrichment in the mantle wedge above a subduction zone

    Science.gov (United States)

    Shervais, John W.; Jean, Marlon M.

    2012-10-01

    Enrichment of the mantle wedge above subduction zones with fluid mobile elements is thought to represent a fundamental process in the origin of arc magmas. This "subduction factory" is typically modeled as a mass balance of inputs (from the subducted slab) and outputs (arc volcanics). We present here a new method to model fluid mobile elements, based on the composition of peridotites associated with supra-subduction ophiolites, which form by melt extraction and fluid enrichment in the mantle wedge above nascent subduction zones. The Coast Range ophiolite (CRO), California, is a Jurassic supra-subduction zone ophiolite that preserves mantle lithologies formed in response to hydrous melting. We use high-precision laser ablation ICP-MS analyses of relic pyroxenes from these peridotites to document fluid-mobile element (FME) concentrations, along with a suite of non-fluid mobile elements that includes rare earth and high-field strength elements. In the CRO, fluid-mobile elements are enriched by factors of up to 100× DMM, whereas fluid immobile elements are progressively depleted by melt extraction. The high concentrations of fluid mobile elements in supra-subduction peridotite pyroxene can be attributed to a flux of aqueous fluid or fluid-rich melt phase derived from the subducting slab. To model this enrichment, we derive a new algorithm that calculates the concentration of fluid mobile elements added to the source: C=[C/[[D/(D-PF)]∗[1-(PF/D)

  7. Brucite as an important phase of the shallow mantle wedge: Evidence from the Shiraga unit of the Sanbagawa subduction zone, SW Japan

    Science.gov (United States)

    Kawahara, Hirokazu; Endo, Shunsuke; Wallis, Simon R.; Nagaya, Takayoshi; Mori, Hiroshi; Asahara, Yoshihiro

    2016-06-01

    Large parts of the shallow mantle wedge are thought to be hydrated due to release of fluids from the subducting slab and serpentinization of the overlying mantle rocks. If serpentinization proceeds under low SiO2 activity, brucite can be a major phase in the low-temperature (< 450 °C) part of the serpentinized mantle wedge, but only very few natural examples have been documented. A combined petrological, geochemical, and geological study shows that brucite is widely distributed in the wedge mantle-derived Shiraga metaserpentinite body in the Sanbagawa metamorphic belt of SW Japan. Thermodynamic modeling combined with bulk rock composition and point counting indicates that the original fully hydrated shallow parts of the Sanbagawa mantle wedge contained ~ 10-15 vol.% brucite before the onset of exhumation of the Shiraga body and before peak metamorphic conditions. A distinct zone of brucite-free essentially monomineralic antigorite serpentinite occurs limited to a 100-m-thick marginal zone of the body. This indicates a limited degree of Si-metasomatism by slab-derived fluids in the shallow mantle wedge. The presence of brucite may strongly affect the H2O budget and mechanical properties of serpentinite; these should be taken into consideration when examining the behavior of the shallow mantle wedge.

  8. Analysis of distribution rule of surface stress on cross wedge rolling contact zone by finite element method

    Science.gov (United States)

    Shu, Xuedao; Li, Lianpeng; Hu, Zhenghuan

    2005-12-01

    Contact surface of cross-wedge rolling is a complicated space surface and distribution rule of contact surface stress is very complicated. So far, its analyzed result was still based on slippery line method. Designing mould and actual production mainly depend on experiential factor. Application and development of cross-wedge rolling was baffled seriously. Based on the forming characteristics of cross-wedge rolling with flat wedge-shape, the ANSYS/DYNA software was developed secondly on the basis of itself, and the corresponding command program was compiled. Rolling process of cross-wedge rolling with flat wedge-shape was simulated successfully. Through simulation, space surface shape of contact surface was achieved, and distribution rule of contact surface stress was analyzed detailed and obtained. The results provide important theoretical foundation for avoiding appearing bug on surface of rolled part, instructing to design cross-wedge mould and confirming force and energy parameter.

  9. Grounding zone system in outer Bjørnøyrenna, Barents Sea - constraints on its genesis and timing

    Science.gov (United States)

    Ruther, Denise; Andreassen, Karin; Forwick, Matthias; Husum, Katrine

    2010-05-01

    A 200 km wide grounding zone system in outer Bjørnøyrenna (Bear Island Trough), south-western Barents Sea, has been investigated using 2D high resolution seismic, sediment gravity cores, regional swath and large scale bathymetry data. Observed sediment facies and three radiocarbon dates from the base of glacimarine units indicate glacier proximal conditions in outermost Bjørnøyrenna between 16,800 and 15,800 cal yrs. The bathymetry data sustain a division into a frontal wedge with a complex morphology of arcuate ridges and depressions, and an upstream part of the wedge characterized by mega scale glacial lineations. A high resolution seismic transect reveals elevation of the sediment deposit of up to 35 m over downstream seafloor and a longitudinal extend of roughly 30 kilometers for the part of the wedge with substantial thicknesses - corresponding to the hummocky frontal wedge. The lobate outline of the sediment wedge together with the arcuate ridge morphologies have earlier led to the hypothesis that the wedge was made of separate lobes which are partly overlapping. The lack of on-lapping strata in a high resolution cross sectional seismic line does however rather suggest the entire wedge to consist of one body of sediment. Based on the distinct morphology and internal structures we infer that the system was deposited during a sudden readvance of the ice front where mega scale glacial lineations have been formed under the grounded ice while pushing and squeezing of soft diluted sediment were the major depositional mechanisms for the hummocky frontal part of the wedge. 10 sediment gravity cores have been recovered from the area. Facies analyses enable the localization of subglacial, glaciproximal, and glacimarine environments in the cores downstream from the wedge, while generally thin non-glacial covers illustrate the Holocene erosive regime on the continental shelf. AMS dates on bulk benthic foraminifera from the bottom of glacimarine units in three of the

  10. Basal conditions at the grounding zone of Whillans Ice Stream, West Antarctica, from ice-penetrating radar

    Science.gov (United States)

    Christianson, Knut; Jacobel, Robert W.; Horgan, Huw J.; Alley, Richard B.; Anandakrishnan, Sridhar; Holland, David M.; DallaSanta, Kevin J.

    2016-11-01

    We present a comprehensive ice-penetrating radar survey of a subglacial embayment and adjacent peninsula along the grounding zone of Whillans Ice Stream, West Antarctica. Through basal waveform and reflectivity analysis, we identify four distinct basal interfaces: (1) an ice-water-saturated till interface inland of grounding; (2) a complex interface in the grounding zone with variations in reflectivity and waveforms caused by reflections from fluting, sediment deposits, and crevasses; (3) an interface of anomalously low-reflectivity downstream of grounding in unambiguously floating areas of the embayment due to basal roughness and entrained debris; and (4) a high-reflectivity ice-seawater interface that occurs immediately seaward of grounding at the subglacial peninsula and several kilometers seaward of grounding in the embayment, occurring after basal debris and grounding zone flutes have melted off the ice bottom. Sediment deposition via basal debris melt-out occurs in both locations. The higher basal melt rate at the peninsula contributes to greater grounding line stability by enabling faster construction of a stabilizing sediment wedge. In the embayment, the low slopes of the ice bottom and bed prevent development of a strong thermohaline circulation leading to a lower basal melt rate and less rapid sediment deposition. Thus, grounding lines in subglacial embayments are more likely to lack stabilizing sediment deposits and are more prone to external forcing, whether from the ocean, the subglacial water system, or large-scale ice dynamics. Our conclusions indicate that subglacial peninsulas and embayments should be treated differently in ice sheet-ocean models if these models are to accurately simulate grounding line response to external forcing.

  11. Arctic ecosystem functional zones: identification and quantification using an above and below ground monitoring strategy

    Science.gov (United States)

    Hubbard, Susan S.; Ajo-Franklin, Jonathan B.; Dafflon, Baptiste; Dou, Shan; Kneafsey, Tim J.; Peterson, John E.; Tas, Neslihan; Torn, Margaret S.; Phuong Tran, Anh; Ulrich, Craig; Wainwright, Haruko; Wu, Yuxin; Wullschleger, Stan

    2015-04-01

    Although accurate prediction of ecosystem feedbacks to climate requires characterization of the properties that influence terrestrial carbon cycling, performing such characterization is challenging due to the disparity of scales involved. This is particularly true in vulnerable Arctic ecosystems, where microbial activities leading to the production of greenhouse gasses are a function of small-scale hydrological, geochemical, and thermal conditions influenced by geomorphology and seasonal dynamics. As part of the DOE Next-Generation Ecosystem Experiment (NGEE-Arctic), we are advancing two approaches to improve the characterization of complex Arctic ecosystems, with an initial application to an ice-wedge polygon dominated tundra site near Barrow, AK, USA. The first advance focuses on developing a new strategy to jointly monitor above- and below- ground properties critical for carbon cycling in the tundra. The strategy includes co-characterization of properties within the three critical ecosystem compartments: land surface (vegetation, water inundation, snow thickness, and geomorphology); active layer (peat thickness, soil moisture, soil texture, hydraulic conductivity, soil temperature, and geochemistry); and permafrost (mineral soil and ice content, nature, and distribution). Using a nested sampling strategy, a wide range of measurements have been collected at the study site over the past three years, including: above-ground imagery (LiDAR, visible, near infrared, NDVI) from various platforms, surface geophysical datasets (electrical, electromagnetic, ground penetrating radar, seismic), and point measurements (such as CO2 and methane fluxes, soil properties, microbial community composition). A subset of the coincident datasets is autonomously collected daily. Laboratory experiments and new inversion approaches are used to improve interpretation of the field geophysical datasets in terms of ecosystem properties. The new strategy has significantly advanced our ability

  12. Ice wedges as climate archives - opportunities and limitations

    Science.gov (United States)

    Opel, Thomas; Meyer, Hanno; Dereviagin, Alexander; Wetterich, Sebastian; Schirrmeister, Lutz

    2014-05-01

    Permafrost regions are assumed to play a major role for Global Climate Change as they are susceptible to recent warming in particular with regard to the potential release of stored fossil carbon. Permafrost serves as archive of past environmental and climate conditions (such as sedimentation processes, temperature and precipitation regimes as well as landscape and ecosystem development) over tens of thousands of years that can be traced by the study of the frozen deposits, paleontological content and ground ice. Ground ice comprises all types of ice contained in frozen ground, including pore ice, segregation ice and ice wedges. Here, we focus on ice wedges as the most promising climate archive that can be studied by stable water isotope methods analogously to glacier ice. They may be identified by their vertically oriented foliations. Ice wedges form by the repeated filling of wintertime thermal contraction cracks by snow melt water in spring. As the melt water quickly refreezes at negative ground temperature no isotopic fractionation takes place. Hence, the isotopic composition (δ18O, δD, d excess) of wedge ice is assumed to be representative of annual cold period climate conditions, i.e. winter and spring. Ice wedges are widely distributed in non-glaciated high northern latitudes, are diagnostic of permafrost and, in general, indicative of cold and stable climate conditions. They are found in continuous and discontinuous permafrost zones and may also have formed during and survived interglacials. They may provide unique paleo information that is not captured by other climate archives. Usually, ice wedges are dated by radiocarbon dating of organic material incorporated in the ice, but also 36Cl/Cl ratios have been successfully used to date ice wedges. Nevertheless reliable age determination is challenging when studying ice wedges. Here we tackle the potential of ice wedges from the Siberian and American Arctic to trace past climate changes from stable isotope

  13. Geophysical evidence for wedging in the San Gorgonio Pass structural knot, southern San Andreas fault zone, southern California

    Science.gov (United States)

    Langenheim, V.E.; Jachens, R.C.; Matti, J.C.; Hauksson, E.; Morton, D.M.; Christensen, A.

    2005-01-01

    Geophysical data and surface geology define intertonguing thrust wedges that form the upper crust in the San Gorgonio Pass region. This picture serves as the basis for inferring past fault movements within the San Andreas system, which are fundamental to understanding the tectonic evolution of the San Gorgonio Pass region. Interpretation of gravity data indicates that sedimentary rocks have been thrust at least 5 km in the central part of San Gorgonio Pass beneath basement rocks of the southeast San Bernardino Mountains. Subtle, long-wavelength magnetic anomalies indicate that a magnetic body extends in the subsurface north of San Gorgonio Pass and south under Peninsular Ranges basement, and has a southern edge that is roughly parallel to, but 5-6 km south of, the surface trace of the Banning fault. This deep magnetic body is composed either of upper-plate rocks of San Gabriel Mountains basement or rocks of San Bernardino Mountains basement or both. We suggest that transpression across the San Gorgonio Pass region drove a wedge of Peninsular Ranges basement and its overlying sedimentary cover northward into the San Bernardino Mountains during the Neogene, offsetting the Banning fault at shallow depth. Average rates of convergence implied by this offset are broadly consistent with estimates of convergence from other geologic and geodetic data. Seismicity suggests a deeper detachment surface beneath the deep magnetic body. This interpretation suggests that the fault mapped at the surface evolved not only in map but also in cross-sectional view. Given the multilayered nature of deformation, it is unlikely that the San Andreas fault will rupture cleanly through the complex structures in San Gorgonio Pass. ?? 2005 Geological Society of America.

  14. Fluid Source-based Modeling of Melt Initiation within the Subduction Zone Mantle Wedge: Implications for Geochemical Trends in Arc Lavas

    Science.gov (United States)

    Hebert, L. B.; Asimow, P. D.; Antoshechkina, P. M.

    2008-12-01

    The GyPSM-S (Geodynamic and Petrological Synthesis Model for Subduction) scheme couples a petrological model (pHMELTS) with a 2D thermal and variable viscosity flow model (ConMan), to describe and compare fundamental processes occurring within subduction zones. Here we supplement basic GyPSM-S models with a more sophisticated treatment of trace element partitioning in the fluid phase and of melt transport regimes to investigate the influences of slab fluid source lithology and fluid transport mechanisms on melt geochemistry, the implications of mantle source depletion related to fluid fluxing, and potential melt migration processes. Changing model parameters indicate that slab age and slab dip are the primary controls on slab-adjacent low-viscosity channel (LVC) shape and thickness, due to changes in the fluid release patterns. Slab age and convergence velocity, which contribute to the slab thermal structure, are significant for the locations of dehydration reactions within the different lithological layers of the slab. The fluid source lithology determines the fluid flux and the fluid-mobile trace element input to the wedge. This study focuses on two cases that represent extremes within our model set, an old slab with a low rate of convergence and and a relatively young slab with a higher rate of convergence. Results are compared to actual geochemical datasets for the Izu-Bonin intra-oceanic subduction system and the Central Costa Rican part of the Central American arc. We find that there is a progression of geochemical characteristics described in studies of cross-arc and along-arc lavas that can be duplicated assuming (i) limited fluid-rock interaction within the mantle wedge and (ii) that melt migration preserves the spatial distinction among melts initiated in different areas of the wedge. Specifically, volcanic front lavas have significant contributions from shallower slab fluid sources, and rear-arc lavas have significant contributions from deeper slab fluid

  15. Rethinking wedges

    Science.gov (United States)

    Davis, Steven J.; Cao, Long; Caldeira, Ken; Hoffert, Martin I.

    2013-03-01

    Abstract Stabilizing CO2 emissions at current levels for fifty years is not consistent with either an atmospheric CO2 concentration below 500 ppm or global temperature increases below 2 °C. Accepting these targets, solving the climate problem requires that emissions peak and decline in the next few decades, and ultimately fall to near zero. Phasing out emissions over 50 years could be achieved by deploying on the order of 19 'wedges', each of which ramps up linearly over a period of 50 years to ultimately avoid 1 GtC y-1 of CO2 emissions. But this level of mitigation will require affordable carbon-free energy systems to be deployed at the scale of tens of terawatts. Any hope for such fundamental and disruptive transformation of the global energy system depends upon coordinated efforts to innovate, plan, and deploy new transportation and energy systems that can provide affordable energy at this scale without emitting CO2 to the atmosphere. 1. Introduction In 2004, Pacala and Socolow published a study in Science arguing that '[h]umanity can solve the carbon and climate problem in the first half of this century simply by scaling up what we already know how to do' [1]. Specifically, they presented 15 options for 'stabilization wedges' that would grow linearly from zero to 1 Gt of carbon emissions avoided per year (GtC y-1 1 Gt = 1012 kg) over 50 years. The solution to the carbon and climate problem, they asserted, was 'to deploy the technologies and/or lifestyle changes necessary to fill all seven wedges of the stabilization triangle'. They claimed this would offset the growth of emissions and put us on a trajectory to stabilize atmospheric CO2 concentration at 500 ppm if emissions decreased sharply in the second half of the 21st century. The wedge concept has proven popular as an analytical tool for considering the potential of different technologies to reduce CO2 emissions. In the years since the paper was published, it has been cited more than 400 times, and

  16. Multiple magmatism in an evolving suprasubduction zone mantle wedge: The case of the composite mafic-ultramafic complex of Gaositai, North China Craton

    Science.gov (United States)

    Yang, Fan; Santosh, M.; Tsunogae, T.; Tang, Li; Teng, Xueming

    2017-07-01

    The suprasubduction zone mantle wedge of active convergent margins is impregnated by melts and fluids leading to the formation of a variety of magmatic and metasomatic rock suites. Here we investigate a composite mafic-ultramafic intrusion at Gaositai, in the northern margin of the North China Craton (NCC). The hornblende gabbro-serpentinite-dunite-pyroxenite-gabbro-diorite suite surrounded by hornblendites of this complex has long been considered to represent an ;Alaskan-type; zoned pluton. We present petrologic, mineral chemical, geochemical and zircon U-Pb and Lu-Hf data from the various rock types from Gaositai including hornblende gabbro, serpentinite, dunite, pyroxenite, diorite and the basement hornblendite which reveal the case of multiple melt generation and melt-peridotite interaction. Our new mineral chemical data from the mafic-ultramafic suite exclude an ;Alaskan-type; affinity, and the bulk geochemical features are consistent with subduction-related magmatism with enrichment of LILE (K, Rb, and Ba) and LREE (La and Ce), and depletion of HFSE (Nb, Ta, Zr, and Hf) and HREE. Zircon U-Pb geochronology reveals that the hornblendites surrounding the Gaositai complex are nearly 2 billion years older than the intrusive complex and yield early Paleoproterozoic emplacement ages (2433-2460 Ma), followed by late Paleoproterozoic metamorphism (1897 Ma). The serpentinites trace the history of a long-lived and replenished ancient sub-continental lithospheric mantle with the oldest zircon population dated as 2479 Ma and 1896 Ma, closely corresponding with the ages obtained from the basement rock, followed by Neoproterozoic and Phanerozoic zircon growth. The oldest member in the Gaositai composite intrusion is the dunite that yields emplacement age of 755 Ma, followed by pyroxenite formed through the interaction of slab melt and wedge mantle peridotite at 401 Ma. All the rock suites also carry multiple population of younger zircons ranging in age from Paleozoic to

  17. Effects of spatially variable snow cover on thermal regime and hydrology of an Arctic ice wedge polygon landscape identified using ground penetrating radar and LIDAR datasets

    Science.gov (United States)

    Gusmeroli, A.; Liljedahl, A. K.; Peterson, J. E.; Hubbard, S. S.; Hinzman, L. D.

    2012-12-01

    Ice wedge polygons are common in Arctic terrains underlain by permafrost. Permafrost degradation could transform low- into high centered polygons, causing profound changes in the hydrologic regime of Arctic lands, which in turn, could affect the energy balance and subsurface biodegradation of organic carbon responsible for greenhouse gas production. Understanding the linkages between microtopography, snow cover, thermal properties, and thaw depth is critical for developing a predictive understanding of terrestrial ecosystems and their feedbacks to climate. In this study, we use high frequency (500-1000 MHz) ground penetrating radar (GPR) data acquired in spring 2012 within the Next Generation Ecosystem Experiment (NGEE) study site in Barrow, AK to characterize the spatial variability of snow distribution. We compare it's distribution to microtopography, estimated using LIDAR data, and thaw depth, also estimated using ground penetrating radar collected at different times during the year and simulated over time using mechanistic thermal-hydrologic modeling. The high spatial resolution offered by LIDAR and ground penetrating radar permit detailed investigations of the control of microtopography on snow and thaw layer depth. Results suggest that microtopographical variations are responsible for substantial differences in snow accumulation. In low centered polygons, snow depth can be up to four times greater in the troughs than on the rims. Both modeling and observations suggest that the microtopography-governed snow thickness affects the thermal properties of the subsurface and thus the thaw layer thickness; regions with thicker snowpack generally correspond to regions of greater thaw depth. We conclude that a transition from low- to high centered polygons will not only impact watershed runoff but, since snow accumulation is sensitive to the microtopography, it will also impact snow distribution. In turn, snow distribution affects thaw depth thickness, and the

  18. Radial wedge flange clamp

    Science.gov (United States)

    Smith, Karl H.

    2002-01-01

    A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

  19. Thermal ground water flow systems in the thrust zone in southeastern Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Ralston, D.R.

    1983-05-01

    The results of a regional study of thermal and non-thermal ground water flow systems in the thrust zone of southern Idaho and western Wyoming are presented. The study involved hydrogeologic and hydrochemical data collection and interpretation. Particular emphasis was placed on analyzing the role that thrust zones play in controlling the movement of thermal and non-thermal fluids.

  20. Devonian lacustrine shore zone architecture imaged with ground penetrating radar

    DEFF Research Database (Denmark)

    Andrews, Steven D.; Moreau, Julien; Archer, Stuart

    of these units. The cycles are on average 15 m thick and comprise deep lake, perennial lake, playa and shore zone facies (2 to 3.5 m in thickness). High resolution sedimentary logging and the construction of photo-panels were combined with high resolution GPR profiling (250 MHz). To ensure close ties between...... produced amalgamated sands, forming low relief bars. Shore zone reworking is likely to have occurred over a wide area as the lake margin migrated back and forth, and gradually transgressed. Continued transgression forced fluvial systems back towards the basin margin....

  1. Melt- versus fluid-induced metasomatism in spinel to garnet wedge peridotites (Ulten Zone, Eastern Italian Alps): clues from trace element and Li abundances

    Science.gov (United States)

    Scambelluri, M.; Hermann, J.; Morten, L.; Rampone, E.

    2006-04-01

    The peridotite bodies of the Ulten Zone (Upper Austroalpine, Italian Eastern Alps) are enclosed in Variscan migmatites and derive from a mantle wedge environment. They display the progressive transformation of porphyroclastic spinel peridotites ( T=1,200°C; P=1.5 GPa) into fine-grained garnet-amphibole peridotites ( T=850°C; P=3 GPa). Detailed bulk-rock and mineral trace element analyses of a sample suite documenting the entire metamorphic evolution of the peridotites revealed several stages of metasomatism. The spinel peridotites derive from a depleted mantle that became enriched in some large ion lithophile element (LILE) and light rare earth elements (LREE). The same signature pertains to clinopyroxene and orthopyroxene, indicating that this metasomatic signature was acquired at the recorded temperature of 1,200°C. Such a temperature is considerably above the wet peridotite solidus and hence the metasomatic agent must have been a hydrous melt. Moreover, the Li-enrichment of the spinel-facies pyroxenes (up to 24 ppm Li) reflects disequilibrium distribution after exchange with a presumably mafic melt. cpx/opx D Li=3-7 and cpx/ol D Li=2.7-8 indicate that the spinel-facies clinopyroxene hosts higher Li amounts than the coexisting minerals. LREE fractionation, variable LREE enrichment, LILE enrichment with respect to HFSE (average clinopyroxene Pb N /Nb N =16-90) in spinel lherzolites can be related to chromatographic effects of porous melt flow. The significant enrichment of pyroxenes from the spinel lherzolites in Pb, U and Li indicates that the metasomatic melt was subduction-related. All these features suggest that the spinel lherzolites formed a mantle wedge layer percolated by melts carrying recycled crustal components and rising from a deeper source of subduction magmas. The garnet + amphibole peridotites equilibrated at temperatures well below the wet solidus in the presence of an aqueous fluid. Bulk-rock trace element patterns display pronounced positive

  2. Material-property zones used in the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Zones in this data set represent spatially contiguous areas that influence ground-water flow in the Death Valley regional ground-water flow system (DVRFS), an...

  3. Material-property zones used in the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Zones in this data set represent spatially contiguous areas that influence ground-water flow in the Death Valley regional ground-water flow system (DVRFS), an...

  4. Devonian lacustrine shore zone architecture imaged with ground penetrating radar

    DEFF Research Database (Denmark)

    Andrews, Steven D.; Moreau, Julien; Archer, Stuart

    deposition was limited to intermittent events where sediment was laid down on a water saturated substrate. Some of these may have occurr­­­ed subaqueously as small scale turbidity flows. High resolution fluctuations in lake level resulted in periodic short lived reworking events along the lake margin which...... produced amalgamated sands, forming low relief bars. Shore zone reworking is likely to have occurred over a wide area as the lake margin migrated back and forth, and gradually transgressed. Continued transgression forced fluvial systems back towards the basin margin....

  5. Vadose zone-attenuated artificial recharge for input to a ground water model.

    Science.gov (United States)

    Nichols, William E; Wurstner, Signe K; Eslinger, Paul W

    2007-01-01

    Accurate representation of artificial recharge is requisite to calibration of a ground water model of an unconfined aquifer for a semiarid or arid site with a vadose zone that imparts significant attenuation of liquid transmission and substantial anthropogenic liquid discharges. Under such circumstances, artificial recharge occurs in response to liquid disposal to the vadose zone in areas that are small relative to the ground water model domain. Natural recharge, in contrast, is spatially variable and occurs over the entire upper boundary of a typical unconfined ground water model. An improved technique for partitioning artificial recharge from simulated total recharge for inclusion in a ground water model is presented. The improved technique is applied using data from the semiarid Hanford Site. From 1944 until the late 1980s, when Hanford's mission was the production of nuclear materials, the quantities of liquid discharged from production facilities to the ground vastly exceeded natural recharge. Nearly all hydraulic head data available for use in calibrating a ground water model at this site were collected during this period or later, when the aquifer was under the diminishing influence of the massive water disposals. The vadose zone is typically 80 to 90 m thick at the Central Plateau where most production facilities were located at this semiarid site, and its attenuation of liquid transmission to the aquifer can be significant. The new technique is shown to improve the representation of artificial recharge and thereby contribute to improvement in the calibration of a site-wide ground water model.

  6. Modeling surface and ground water mixing in the hyporheic zone using MODFLOW and MT3D

    Science.gov (United States)

    Lautz, Laura K.; Siegel, Donald I.

    2006-11-01

    We used a three-dimensional MODFLOW model, paired with MT3D, to simulate hyporheic zones around debris dams and meanders along a semi-arid stream. MT3D simulates both advective transport and sink/source mixing of solutes, in contrast to particle tracking (e.g. MODPATH), which only considers advection. We delineated the hydrochemically active hyporheic zone based on a new definition, specifically as near-stream subsurface zones receiving a minimum of 10% surface water within a 10-day travel time. Modeling results indicate that movement of surface water into the hyporheic zone is predominantly an advective process. We show that debris dams are a key driver of surface water into the subsurface along the experimental reach, causing the largest flux rates of water across the streambed and creating hyporheic zones with up to twice the cross-sectional area of other hyporheic zones. Hyporheic exchange was also found in highly sinuous segments of the experimental reach, but flux rates are lower and the cross-sectional areas of these zones are generally smaller. Our modeling approach simulated surface and ground water mixing in the hyporheic zone, and thus provides numerical approximations that are more comparable to field-based observations of surface-groundwater exchange than standard particle-tracking simulations.

  7. Ground motion parameters of Shillong plateau: One of the most seismically active zones of northeastern India

    Institute of Scientific and Technical Information of China (English)

    Saurabh Baruah; Santanu Baruah; Naba Kumar Gogoi; Olga Erteleva; Felix Aptikaev; J.R.Kayal

    2009-01-01

    Strong ground motion parameters for Shillong plateau of northeastern India are examined. Empirical relations are obtained for main parameters of ground motions as a function of earthquake magnitude, fault type, source depth, velocity characterization of medium and distance. Correlation between ground motion parameters and characteristics of seismogenic zones are established. A new attenuation relation for peak ground acceleration is developed, which predicts higher expected PGA in the region. Parameters of strong motions, particularly the predominant periods and duration of vibrations, depend on the morphology of the studied area. The study measures low estimates of logarithmic width in Shillong plateau. The attenuation relation estimated for pulse width critically indicates increased pulse width dependence on the logarithmic distance which accounts for geometrical spreading and anelastic attenuation.

  8. Three Years of High Resolution Year-Round Monitoring of Ice-Wedge Thermal Contraction Cracking in Svalbard

    Science.gov (United States)

    Christiansen, H. H.

    2006-12-01

    Most likely ice-wedges are the most widespread periglacial landform in lowlands with continuous permafrost. With a changing climate it is important to understand better the geomorphological processes controlling ice- wedge growth and decay, as they might cause large changes to the surface of the landscape, particularly if the active layer thickness increases causing melting of the most ice-rich permafrost top layer. As most settlements on permafrost are located in lowland areas, ice-wedge formation can also influence the infrastructure. Understanding the processes of ice-wedge growth and their thaw transformation into ice-wedge casts are essential when using contemporary ice wedges as analogues of Pleistocene thermal contraction cracking in palaeoenvironmental reconstructions. As ice-wedges are largely controlled by winter conditions, improved understanding of the factors controlling their growth will enable better palaeoclimatic reconstructions both directly from ice-wedges, but also from ice-wedge casts, than just mean winter temperatures. Detailed studies of ice-wedge dynamics, including quantification of movement, have only been done in very few places in the Arctic. In high arctic Svalbard at 78°N climate at sea level locates these islands close to the southern limit of the continuous permafrost zone, with MAAT of as much as -4 to -6°C. However, thermal contraction cracking is demonstrated to be widespread in the Adventdalen study area in Svalbard. The year-round field access from the University Centre in Svalbard, UNIS, has enabled the collection of different continuous or high frequency ice-wedge process monitoring data since 2002 to improve the understanding of the geomorphological activity of this landform. In all the winters the air temperature was below -30°C for shorter or longer periods. During all the winters, the temperature in the top permafrost was below -15°C both in the ice-wedge top for shorter or longer periods. The snow cover was

  9. Characterizing Englacial Attenuation and Grounding Zone Geometry Using Airborne Radar Sounding

    Science.gov (United States)

    Schroeder, D. M.; Grima, C.; Blankenship, D. D.

    2014-12-01

    The impact of warm ocean water on ice sheet retreat and stability is a one of the primary drivers and sources of uncertainty for the rate of global sea level rise. One critical but challenging observation required to understand and model this impact is the location and extent of grounding ice sheet zones. However, existing surface topography based techniques do not directly detect the location where ocean water reaches (or breaches) grounded ice at the bed, which can significantly affect ice sheet stability. The primary geophysical tool for directly observing the basal properties of ice sheets is airborne radar sounding. However, uncertainty in englacial attenuation from unknown ice temperature and chemistry can lead to erroneous interpretation of subglacial conditions from bed echo strengths alone . Recently developed analysis techniques for radar sounding data have overcome this challenge by taking advantage of information in the angular distribution of bed echo energy and joint modeling of radar returns and water routing. We have developed similar approaches to analyze the spatial pattern and character of echoes to address the problems of improved characterization of grounding zone geometry and englacial attenuation. The spatial signal of the transition from an ice-bed interface to an ice-ocean interface is an increase in bed echo strength. However, rapidly changing attenuation near the grounding zone prevents the unambiguous interpretation of this signal in typical echo strength profiles and violates the assumptions of existing empirical attenuation correction techniques. We present a technique that treat bed echoes as continuous signals to take advantage of along-profile ice thickness and echo strength variations to constrain the spatial pattern of attenuation and detect the grounding zone transition. The transition from an ice-bed interface to an ice-ocean interface will also result in a change in the processes that determine basal interface morphology (e

  10. Effects and implications of fault zone heterogeneity and anisotropy on earthquake strong ground motion

    Science.gov (United States)

    Su, Wei-Jou

    This thesis consists of two parts. Part one is concerned with the effect of fault zone heterogeneity on the strong ground motion of the Loma Preita earthquake. Part two is concerned with the effect of the effective hexagonal anisotropy of a fault zone on strong ground motion. A superposition of Gaussian beams is used to analyze these problems because it can account for both the rupture history of the fault plane and the fault zone heterogeneity. We also extend this method to investigate the combined effects of the rupture process on a fault plane and medium anisotropy on the synthetic seismograms. The strong ground motion of the Loma Prieta Earthquake is synthesized using a known three-dimensional crustal model of the region, a rupture model determined under the assumption of laterally homogeneous structure, and Green's functions computed by superposition of Gaussian beams. Compared to results obtained assuming a laterally homogeneous crust, stations lying to the northeast of the rupture zone are predicted to be defocused, while stations lying to the west of the fault trace are predicted to be focused. The defocusing is caused by a zone of high velocity material between the San Andreas and Sargent faults, and the focusing is caused by a region of low velocity lying between the Zayantes and San Andreas faults. If lateral homogeneity is assumed, the net effect of the predicted focusing and defocusing is to bias estimates of the relative slip of two high slip regions found in inversions of local and teleseismic body waves. These biases are similar in magnitude to those estimated for waveform inversions from the effects of using different subsets of data and/or different misfit functions and are similar in magnitude to the effects predicted for non-linear site responses.

  11. Effects of water, depth and temperature on partial melting of mantle-wedge fluxed by hydrous sediment-melt in subduction zones

    Science.gov (United States)

    Mallik, Ananya; Dasgupta, Rajdeep; Tsuno, Kyusei; Nelson, Jared

    2016-12-01

    This study investigates the partial melting of variable bulk H2O-bearing parcels of mantle-wedge hybridized by partial melt derived from subducted metapelites, at pressure-temperature (P-T) conditions applicable to the hotter core of the mantle beneath volcanic arcs. Experiments are performed on mixtures of 25% sediment-melt and 75% fertile peridotite, from 1200 to 1300 °C, at 2 and 3 GPa, with bulk H2O concentrations of 4 and 6 wt.%. Combining the results from these experiments with previous experiments containing 2 wt.% bulk H2O (Mallik et al., 2015), it is observed that all melt compositions, except those produced in the lowest bulk H2O experiments at 3 GPa, are saturated with olivine and orthopyroxene. Also, higher bulk H2O concentration increases melt fraction at the same P-T condition, and causes exhaustion of garnet, phlogopite and clinopyroxene at lower temperatures, for a given pressure. The activity coefficient of silica (ϒSiO2) for olivine-orthopyroxene saturated melt compositions (where the activity of silica, aSiO2 , is buffered by the reaction olivine + SiO2 = orthopyroxene) from this study and from mantle melting studies in the literature are calculated. In melt compositions generated at 2 GPa or shallower, with increasing H2O concentration, ϒSiO2 increases from transition from non-ideal mixing as OH- in the melt (ϒSiO2 2 GPa, ϒSiO2 >1 at higher H2O concentrations in the melt, indicate requirement of excess energy to incorporate molecular H2O in the silicate melt structure, along with a preference for bridging species and polyhedral edge decorations. With vapor saturation in the presence of melt, ϒSiO2 decreases indicating approach towards ideal mixing of H2O in silicate melt. For similar H2O concentrations in the melt, ϒSiO2 for olivine-orthopyroxene saturated melts at 3 GPa is higher than melts at 2 GPa or shallower. This results in melts generated at 3 GPa being more silica-poor than melts at 2 GPa. Thus, variable bulk H2O and pressure of

  12. Ground Motion Zoning of Santiago de Cuba: An Approach by SH Waves Modelling

    Science.gov (United States)

    Alvarez, Leonardo; García, Julio; Vaccari, Franco; Panza, Giuliano F.; González, Bertha; Reyes, Carmen; Fernández, Bárbara; Pico, Ramón; Zapata, José A.; Arango, Enrique

    The expected ground motion in Santiago de Cuba basin from earthquakes which occurred in the Oriente fault zone is studied. Synthetic SH-waves seismograms have been calculated along four profiles in the basin by the hybrid approach (modal summation for the path source-profile and finite differences for the profile) for a maximum frequency of 1 Hz. The response spectra ratio (RSR) has been determined in 49 sites, distributed along all considered profiles with a spacing of 900 m. The corresponding RSR versus frequency curves have been classified using a logical-combinatorial algorithm. The results of the classification, in combination with the uppermost geological setting (geotechnical information and geological geometry of the subsoil) are used for the seismic zoning of the city. Three different main zones are identified, and a small sector characterized by major resonance effects, due to the particular structural conditions. Each zone is characterized in terms of its expected ground motion parameters for the most probable strong earthquake (MS=7), and for the maximum possible (MS=8).

  13. Mantle wedge dynamics from seismic anisotropy (Invited)

    Science.gov (United States)

    Long, M. D.; Wirth, E. A.

    2013-12-01

    The mantle wedge above subducting slabs plays a critical role in many of the physical processes associated with subduction, including water transport into the upper mantle and the generation and transport of melts. Our understanding of mantle wedge dynamics is incomplete; in particular, the mantle flow field above subducting slabs remains poorly understood. Because seismic anisotropy is a consequence of deformation, observations of anisotropy (such as shear wave splitting and P-to-SH converted waves) can constrain the geometry of the wedge flow field. Additionally, because the presence of water (either in nominally anhydrous minerals or as hydrous phases) can have a large effect on anisotropic structure, a detailed understanding of mantle wedge anisotropy can help to constrain processes related to water cycling in subduction systems. We present a global, synoptic view of anisotropy observations in subduction zone mantle wedges, compiled from a large number of individual studies, with the goal of understanding the first-order controls on wedge anisotropy and flow patterns. This compilation allows us to explicitly test the predictions made by many different conceptual models for wedge anisotropy, as well as to explore the relationships between observed anisotropy parameters and other parameters that describe subduction. We find that no simple model can explain all of the trends observed in the global data set. Mantle wedge flow is likely controlled by a combination of downdip motion of the slab, trench migration, ambient mantle flow, small-scale convection, proximity to slab edges, and slab morphology, with the relative contributions of these in any given subduction system controlled by the subduction kinematics and mantle rheology. There is also a likely contribution from B-type olivine and/or serpentinite fabric in many subduction zones, governed by the local thermal structure and volatile distribution.

  14. Ground-Based Lidar Measurements During the CALIPSO and Twilight Zone (CATZ) Campaign

    Science.gov (United States)

    Berkoff, Timothy; Qian, Li; Kleidman, Richard; Stewart, Sebastian; Welton, Ellsworth; Li, Zhu; Holbem, Brent

    2008-01-01

    The CALIPSO and Twilight Zone (CATZ) field campaign was carried out between June 26th and August 29th of 2007 in the multi-state Maryland-Virginia-Pennsylvania region of the U.S. to study aerosol properties and cloud-aerosol interactions during overpasses of the CALIPSO satellite. Field work was conducted on selected days when CALIPSO ground tracks occurred in the region. Ground-based measurements included data from multiple Cimel sunphotometers that were placed at intervals along a segment of the CALIPSO ground-track. These measurements provided sky radiance and AOD measurements to enable joints inversions and comparisons with CALIPSO retrievals. As part of this activity, four ground-based lidars provided backscatter measurements (at 523 nm) in the region. Lidars at University of Maryland Baltimore County (Catonsville, MD) and Goddard Space Flight Center (Greenbelt, MD) provided continuous data during the campaign, while two micro-pulse lidar (MPL) systems were temporarily stationed at various field locations directly on CALIPSO ground-tracks. As a result, thirteen on-track ground-based lidar observations were obtained from eight different locations in the region. In some cases, nighttime CALIPSO coincident measurements were also obtained. In most studies reported to date, ground-based lidar validation efforts for CALIPSO rely on systems that are at fixed locations some distance away from the satellite ground-track. The CATZ ground-based lidar data provide an opportunity to examine vertical structure properties of aerosols and clouds both on and off-track simultaneously during a CALIPSO overpass. A table of available ground-based lidar measurements during this campaign will be presented, along with example backscatter imagery for a number of coincident cases with CALIPSO. Results indicate that even for a ground-based measurements directly on-track, comparisons can still pose a challenge due to the differing spatio-temporal properties of the ground and satellite

  15. Insights into the Thwaites Glacier grounding zone from Operation IceBridge aerogravity

    Science.gov (United States)

    Tinto, K. J.; Bell, R. E.; Cochran, J. R.; Elieff, S.; Frearson, N.

    2010-12-01

    Operation IceBridge acquired 1500 km of geophysical data, at 10 km spacing, in front of the Thwaites Glacier grounding line during the 2009 season. The gravity anomalies recorded by the survey have been used to model the bathymetry of the sea floor in front of the glacier, an area inaccessible to previous surveys. The resulting map reveals previously unseen detail of the Thwaites grounding zone, as well as the spatial extent of features that were formerly only known as points affecting the ice surface. The modeled bathymetry in front of Thwaites Glacier is marked by an undulating ridge running sub-parallel to the grounding line, 40 km seaward. The highest peak on the ridge is in contact with the overlying ice shelf, hindering its flow. Ridge elevation decreases to the west, with a maximum ridge depth of 850 m and an average relief of 350 m. This is comparable in scale to the recently identified ridge crossing the channel of nearby Pine Island Glacier (Jenkins et al., 2010). The present-day grounding line of Thwaites appears to be marked by a more subdued ridge, in which we have identified a 20 km wide hollow, to a water depth of 1200 m. Our model shows that this hollow corresponds to a landward bight in the grounding line, in the region through which the fast ice flow of Thwaites Glacier is focused. This correlation was not visible on previous, coarser scale maps of the grounding line, and shows a clear relationship between the bathymetry and ice flow. Gravity inversions have been constrained by nearby marine surveys, satellite images of the ice rise at the peak of the ridge and radar and laser data from the IceBridge survey to constrain ice thickness. The absolute values of predicted bathymetry are dependent on the density of the rocks in the subsurface, for example the presence or absence of volcanic material or loose sediments. Some models of the geology of the survey area are also proposed. Uncertainty of underlying geology may account for ~100 m errors in the

  16. Effect of Bulk Water Concentration on Mantle Wedge Hybridization by Rhyolitic Sediment Melt - Implications for Generation of K-rich Basalts to Andesites in Subduction Zones

    Science.gov (United States)

    Mallik, A.; Dasgupta, R.; Nelson, J. M.; Tsuno, K.

    2014-12-01

    Similarities in trace element geochemistry between ocean-floor sediments and arc lavas suggest the involvement of subducted sediments in the mantle source of arc volcanoes. Siliciclastic sediments produce rhyo-dacitic, hydrous partial melts at sub-arc depths, which must react with wedge peridotite during their ascent. In addition to fluids, these sediment melts can be a major carrier of water to the arc source. Here we investigate the effects of bulk water concentration on the phase equilibria of reaction between sediment partial melt and peridotite. Piston-cylinder experiments were performed using Au-Pd capsules, at 2 and 3 GPa, 1050 - 1350 °C with mixtures of 25% rhyolite + 75% lherzolite, bearing bulk water content of 2 (low-water) and 4 wt.% (high-water). Melting degree is higher in high-water experiments at both 2 and 3 GPa with a sharp increase in melt mode from 31 to 53 wt.% at 1250-1300 °C, 2 GPa and 21 to 49 wt.% at 1225-1250 °C, 3 GPa. This sharp increase in melt mode is accompanied by a corresponding abrupt increase in residual olivine to opx ratio at both pressures (0.11 to 0.53 at 1250-1300 °C, 2 GPa and 0 to 0.71 at 1225-1250 °C, 3 GPa). The stability field of phlogopite, clinopyroxene, and garnet are reduced in high-water experiments due to higher degrees of partial melting. Low-water experiments produce basalts with SiO2, on a volatile-free basis, increasing from 49 to 51 wt.% at 2 GPa and 46 to 48 wt.% at 3 GPa. For high-water experiments, melt SiO2 contents at 2 GPa are slightly higher than those in low-water experiments for a given temperature, varying from 51 to 52 wt.%, and, at 3 GPa, the melts trend towards andesitic compositions with SiO2 ~54 wt.%. These compositional characteristics of the melts can be attributed to the effect of increased olivine to opx ratios in the residue as a function of increasing bulk water concentration. Our study shows that a spectrum of ultra-potassic, high-Mg arc lavas (MgO varying from 10-16 wt.%) from

  17. Ground Water Redox Zonation near La Pine, Oregon: Relation to River Position within the Aquifer-Riparian Zone Continuum

    Science.gov (United States)

    Hinkle, Stephen R.; Morgan, David S.; Orzol, Leonard L.; Polette, Danial J.

    2007-01-01

    Increasing residential development since in the 1960s has lead to increases in nitrate concentrations in shallow ground water in parts of the 247 square mile study area near La Pine, Oregon. Denitrification is the dominant nitrate-removal process that occurs in suboxic ground water, and suboxic ground water serves as a barrier to transport of most nitrate in the aquifer. Oxic ground water, on the other hand, represents a potential pathway for nitrate transport from terrestrial recharge areas to the Deschutes and Little Deschutes Rivers. The effects of present and potential future discharge of ground-water nitrate into the nitrogen-limited Deschutes and Little Deschutes Rivers are not known. However, additions of nitrogen to nitrogen-limited rivers can lead to increases in primary productivity which, in turn, can increase the magnitudes of dissolved oxygen and pH swings in river water. An understanding of the distribution of oxic ground water in the near-river environment could facilitate understanding the vulnerability of these rivers and could be a useful tool for management of these rivers. In this study, transects of temporary wells were installed in sub-river sediments beneath the Deschutes and Little Deschutes Rivers near La Pine to characterize near-river reduction/oxidation (redox) conditions near the ends of ground-water flow paths. Samples from transects installed near the center of the riparian zone or flood plain were consistently suboxic. Where transects were near edges of riparian zones, most ground-water samples also were suboxic. Oxic ground water (other than hyporheic water) was uncommon, and was only detected near the outside edge of some meander bends. This pattern of occurrence likely reflects geochemical controls throughout the aquifer as well as geochemical processes in the microbiologically active riparian zone near the end of ground-water flow paths. Younger, typically less reduced ground water generally enters near-river environments through

  18. Ground Water Redox Zonation near La Pine, Oregon: Relation to River Position within the Aquifer-Riparian Zone Continuum

    Science.gov (United States)

    Hinkle, Stephen R.; Morgan, David S.; Orzol, Leonard L.; Polette, Danial J.

    2007-01-01

    Increasing residential development since in the 1960s has lead to increases in nitrate concentrations in shallow ground water in parts of the 247 square mile study area near La Pine, Oregon. Denitrification is the dominant nitrate-removal process that occurs in suboxic ground water, and suboxic ground water serves as a barrier to transport of most nitrate in the aquifer. Oxic ground water, on the other hand, represents a potential pathway for nitrate transport from terrestrial recharge areas to the Deschutes and Little Deschutes Rivers. The effects of present and potential future discharge of ground-water nitrate into the nitrogen-limited Deschutes and Little Deschutes Rivers are not known. However, additions of nitrogen to nitrogen-limited rivers can lead to increases in primary productivity which, in turn, can increase the magnitudes of dissolved oxygen and pH swings in river water. An understanding of the distribution of oxic ground water in the near-river environment could facilitate understanding the vulnerability of these rivers and could be a useful tool for management of these rivers. In this study, transects of temporary wells were installed in sub-river sediments beneath the Deschutes and Little Deschutes Rivers near La Pine to characterize near-river reduction/oxidation (redox) conditions near the ends of ground-water flow paths. Samples from transects installed near the center of the riparian zone or flood plain were consistently suboxic. Where transects were near edges of riparian zones, most ground-water samples also were suboxic. Oxic ground water (other than hyporheic water) was uncommon, and was only detected near the outside edge of some meander bends. This pattern of occurrence likely reflects geochemical controls throughout the aquifer as well as geochemical processes in the microbiologically active riparian zone near the end of ground-water flow paths. Younger, typically less reduced ground water generally enters near-river environments through

  19. Mantle wedge serpentinization effects on slab dips

    Directory of Open Access Journals (Sweden)

    Eh Tan

    2017-01-01

    Full Text Available The mechanical coupling between a subducting slab and the overlying mantle wedge is an important factor in controlling the subduction dip angle and the flow in mantel wedge. This paper investigates the role of the amount of mantle serpentinization on the subduction zone evolution. With numerical thermos-mechanical models with elasto-visco-plastic rheology, we vary the thickness and depth extent of mantle serpentinization in the mantle wedge to control the degree of coupling between the slab and mantle wedge. A thin serpentinized mantle layer is required for stable subduction. For models with stable subduction, we find that the slab dip is affected by the down-dip extent and the mantle serpentinization thickness. A critical down-dip extent exists in mantle serpentinization, determined by the thickness of the overriding lithosphere. If the down-dip extent does not exceed the critical depth, the slab is partially coupled to the overriding lithosphere and has a constant dip angle regardless of the mantle serpentinization thickness. However, if the down-dip extent exceeds the critical depth, the slab and the base of the overriding lithosphere would be separated and decoupled by a thick layer of serpentinized peridotite. This allows further slab bending and results in steeper slab dip. Increasing mantle serpentinization thickness will also result in larger slab dip. We also find that with weak mantle wedge, there is no material flowing from the asthenosphere into the serpentinized mantle wedge. All of these results indicate that serpentinization is an important ingredient when studying the subduction dynamics in the mantle wedge.

  20. Ground-Water Capture Zone Delineation of Hypothetical Systems: Methodology Comparison and Real-World Applications

    Science.gov (United States)

    Ahern, J. A.; Lilly, M. R.; Hinzman, L. D.

    2003-12-01

    A capture zone is the aquifer volume through which ground-water flows to a pumping well over a given time of travel. Determining a well's capture zone aids in water-supply management by creating an awareness of the water source. This helps ensure sustainable pumping operations and outlines areas where protection from contamination is critical. We are delineating the capture zones of hypothetical conceptual models that resemble the Fairbanks, Alaska floodplain both in aquifer parameters and boundary conditions. We begin with a very simple hydrogeologic system and gradually add complexity such as heterogeneity, anisotropy, multiple wells, and zones of permafrost. Commonly-used delineation methods are applied to each case. These include calculated fixed-radius, analytical and numerical models. The calculated fixed-radius method uses a mathematical equation with several simplifying assumptions. Analytical techniques employ a series of equations that likewise assume simple conditions, although to a lesser degree than the fixed-radius method. Our chosen numerical model is MODFLOW-2000, which offers a particle-tracking package (MODPATH) for delineating recharge areas. The delineations are overlayed for each conceptual model in order to compare the capture zones produced by the different methods. Contrasts between capture zones increase with the complexity of the hydrogeology. Simpler methods are restricted by their underlying assumptions. When methods can no longer account for complexities in the conceptual model, the resulting delineations remain similar to those of simpler models. Meanwhile, the zones generated by more sophisticated methods are able to change with changes to the conceptual model. Hence, the simpler methods now lack accuracy and credibility. We have found that these simpler techniques tend to overestimate the capture zone. Water-supply managers must consider such inaccuracies when evaluating the costs of each method. In addition to comparing delineation

  1. Estimation of peak ground accelerations for Mexican subduction zone earthquakes using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Silvia R; Romo, Miguel P; Mayoral, Juan M [Instituto de Ingenieria, Universidad Nacional Autonoma de Mexico, Mexico D.F. (Mexico)

    2007-01-15

    An extensive analysis of the strong ground motion Mexican data base was conducted using Soft Computing (SC) techniques. A Neural Network NN is used to estimate both orthogonal components of the horizontal (PGAh) and vertical (PGAv) peak ground accelerations measured at rock sites during Mexican subduction zone earthquakes. The work discusses the development, training, and testing of this neural model. Attenuation phenomenon was characterized in terms of magnitude, epicentral distance and focal depth. Neural approximators were used instead of traditional regression techniques due to their flexibility to deal with uncertainty and noise. NN predictions follow closely measured responses exhibiting forecasting capabilities better than those of most established attenuation relations for the Mexican subduction zone. Assessment of the NN, was also applied to subduction zones in Japan and North America. For the database used in this paper the NN and the-better-fitted- regression approach residuals are compared. [Spanish] Un analisis exhaustivo de la base de datos mexicana de sismos fuertes se llevo a cabo utilizando tecnicas de computo aproximado, SC (soft computing). En particular, una red neuronal, NN, es utilizada para estimar ambos componentes ortogonales de la maxima aceleracion horizontal del terreno, PGAh, y la vertical, PGAv, medidas en sitios en roca durante terremotos generados en la zona de subduccion de la Republica Mexicana. El trabajo discute el desarrollo, entrenamiento, y prueba de este modelo neuronal. El fenomeno de atenuacion fue caracterizado en terminos de la magnitud, la distancia epicentral y la profundidad focal. Aproximaciones neuronales fueron utilizadas en lugar de tecnicas de regresion tradicionales por su flexibilidad para tratar con incertidumbre y ruido en los datos. La NN sigue de cerca la respuesta medida exhibiendo capacidades predictivas mejores que las mostradas por muchas de las relaciones de atenuacion establecidas para la zona de

  2. Wedges of Anxiety

    DEFF Research Database (Denmark)

    Hellström, Maria; Brandt, Eva

    2005-01-01

    The Heraclitian notion of a reality in constant flux seems to have settled even in the public consciousness. We are, to an ever-increasing extent, on the move; in motion between different places of abode, between domiciles and places of residence, between temporary addresses and provisory settlem...... cones of light, as the cut their way into the unknown, like wedges of anxiety...

  3. Fluid-mediated mass transfer from a paleosubduction channel to its mantle wedge: Evidence from jadeitite and related rocks from the Guatemala Suture Zone

    Science.gov (United States)

    Harlow, George E.; Flores, Kennet E.; Marschall, Horst R.

    2016-08-01

    Jadeitites in serpentinite mélanges are the product of crystallization from and/or metasomatism by aqueous fluids that transfer components from and within a subduction channel-the slab-mantle interaction volume-into discrete rock units, most commonly found within the serpentinized or serpentinizing portion of the channel or the overlying mantle rocks at high pressure (1 to > 2 GPa). Two serpentinite mélanges on either side of the Motagua fault system (MFS) of the Guatemala Suture Zone contain evidence of this process. Whole rock compositional analyses are reported here from 86 samples including jadeitites and the related rocks: omphacitites, albitites and mica rocks. The predominance of a single phase in most of these rocks is reflected in the major element compositions and aspects of the trace elements, such as REE abundances tracking Ca in clinopyroxene. Relative to N-MORB all samples show relative enrichments in the high field strength elements (HFSE) Hf, Zr, U, Th, and the LILE Ba and Cs, contrasted by depletions in K and in some cases Pb or Sr. Most jadeitites are also depleted in the highly compatible elements Cr, Sc and Ni despite their occurrence in serpentinite mélange; however, some omphacitite samples show the opposite. Trace elements in these jadeitite samples show a strong similarity with GLOSS (globally subducted oceanic sediment) and other terrigenous sediments in terms of their trace-element patterns, but are offset to lower abundances. Jadeitites thus incorporate a strong trace-element signature derived from sediments mixed with that from fluid derived from altered oceanic crust. Enrichment in the HFSE argues for mobility of these elements in aqueous fluids at high P/T conditions in the subduction channel and a remarkable lack of fractionation that might otherwise be expected from dissolution and fluid transport.

  4. Shock detachment from curved wedges

    Science.gov (United States)

    Mölder, S.

    2017-03-01

    Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.

  5. Shock detachment from curved wedges

    Science.gov (United States)

    Mölder, S.

    2017-09-01

    Curved shock theory is used to show that the flow behind attached shocks on doubly curved wedges can have either positive or negative post-shock pressure gradients depending on the freestream Mach number, the wedge angle and the two wedge curvatures. Given enough wedge length, the flow near the leading edge can choke to force the shock to detach from the wedge. This local choking can preempt both the maximum deflection and the sonic criteria for shock detachment. Analytical predictions for detachment by local choking are supported by CFD results.

  6. [Selection of back-ground electrolyte in capillary zone electrophoresis by triangle and tetrahedron optimization methods].

    Science.gov (United States)

    Sun, Guoxiang; Song, Wenjing; Lin, Ting

    2008-03-01

    The triangle and tetrahedron optimization methods were developed for the selection of back-ground electrolyte (BGE) in capillary zone electrophoresis (CZE). Chromatographic fingerprint index F and chromatographic fingerprint relative index F(r) were used as the objective functions for the evaluation, and the extract of Saussurea involucrate by water was used as the sample. The BGE was composed of borax, boric acid, dibasic sodium phosphate and sodium dihydrogen phosphate solution with different concentrations using triangle and tetrahedron optimization methods. Re-optimization was carried out by adding organic modifier to the BGE and adjusting the pH value. In triangle method, when 50 mmol/L borax-150 mmol/L sodium dihydrogen phosphate (containing 3% acetonitrile) (1 : 1, v/v) was used as BGE, the isolation was considered to be satisfactory. In tetrahedron method, the best BGE was 50 mmol/L borax-150 mmol/L sodium dihydrogen phosphate-200 mmol/L boric acid (1 : 1 : 2, v/v/v; adjusting the pH value to 8.55 by 0.1 mol/L sodium hydroxide). There were 28 peaks and 25 peaks under the different conditions respectively. The results showed that the methods could be applied to the selection of BGE in CZE of the extract of traditional Chinese medicine by water or ethanol.

  7. Life at the wedge: the activity and diversity of arctic ice wedge microbial communities.

    Science.gov (United States)

    Wilhelm, Roland C; Radtke, Kristin J; Mykytczuk, Nadia C S; Greer, Charles W; Whyte, Lyle G

    2012-04-01

    The discovery of polygonal terrain on Mars underlain by ice heightens interest in the possibility that this water-bearing habitat may be, or may have been, a suitable habitat for extant life. The possibility is supported by the recurring detection of terrestrial microorganisms in subsurface ice environments, such as ice wedges found beneath tundra polygon features. A characterization of the microbial community of ice wedges from the high Arctic was performed to determine whether this ice environment can sustain actively respiring microorganisms and to assess the ecology of this extreme niche. We found that ice wedge samples contained a relatively abundant number of culturable cells compared to other ice habitats (∼10(5) CFU·mL(-1)). Respiration assays in which radio-labeled acetate and in situ measurement of CO(2) flux were used suggested low levels of microbial activity, though more sensitive techniques are required to confirm these findings. Based on 16S rRNA gene pyrosequencing, bacterial and archaeal ice wedge communities appeared to reflect surrounding soil communities. Two Pseudomonas sp. were the most abundant taxa in the ice wedge bacterial library (∼50%), while taxa related to ammonia-oxidizing Thaumarchaeota occupied 90% of the archaeal library. The tolerance of a variety of isolates to salinity and temperature revealed characteristics of a psychrotolerant, halotolerant community. Our findings support the hypothesis that ice wedges are capable of sustaining a diverse, plausibly active microbial community. As such, ice wedges, compared to other forms of less habitable ground ice, could serve as a reservoir for life on permanently cold, water-scarce, ice-rich extraterrestrial bodies and are therefore of interest to astrobiologists and ecologists alike. .

  8. Benchmarking numerical models of brittle thrust wedges

    Science.gov (United States)

    Buiter, Susanne J. H.; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher

    2016-11-01

    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedge test, showing negligible internal deformation and maintaining the initial surface slope upon horizontal translation over a frictional interface. Eight codes participated in the unstable wedge test that examines the evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. The critical taper is recovered, but the models show two deformation modes characterised by either mainly forward dipping thrusts or a series of thrust pop-ups. We speculate that the two modes are caused by differences in effective basal boundary friction related to different algorithms for modelling boundary friction. The third experiment examines stacking of forward thrusts that are translated upward along a backward thrust. The results of the seven codes that run this experiment show variability in deformation style, number of thrusts, thrust dip angles and surface slope. Overall, our experiments show that numerical models run with different numerical techniques can successfully simulate laboratory brittle thrust wedge models at the cm-scale. In more detail, however, we find that it is challenging to reproduce sandbox-type setups numerically, because of frictional boundary conditions and velocity discontinuities. We recommend that future numerical-analogue comparisons use simple boundary conditions and that the numerical Earth Science community defines a plasticity test to resolve the variability in model shear zones.

  9. Mantle flow in subduction systems: The mantle wedge flow field and implications for wedge processes

    Science.gov (United States)

    Long, Maureen D.; Wirth, Erin A.

    2013-02-01

    The mantle wedge above subducting slabs is associated with many important processes, including the transport of melt and volatiles. Our understanding of mantle wedge dynamics is incomplete, as the mantle flow field above subducting slabs remains poorly understood. Because seismic anisotropy is a consequence of deformation, measurements of shear wave splitting can constrain the geometry of mantle flow. In order to identify processes that make first-order contributions to the pattern of wedge flow, we have compiled a data set of local S splitting measurements from mantle wedges worldwide. There is a large amount of variability in splitting parameters, with average delay times ranging from ~0.1 to 0.3 s up to ~1.0-1.5 s and large variations in fast directions. We tested for relationships between splitting parameters and a variety of parameters related to subduction processes. We also explicitly tested the predictions made by 10 different models that have been proposed to explain splitting patterns in the mantle wedge. We find that no simple model can explain all of the trends observed in the global data set. Mantle wedge flow is likely controlled by a combination of downdip motion of the slab, trench migration, ambient mantle flow, small-scale convection, proximity to slab edges, and slab morphology, with the relative contributions of these in any given subduction system controlled by the subduction kinematics and mantle rheology. There is also a likely contribution from B-type olivine and/or serpentinite fabric in many subduction zones, governed by the local thermal structure and volatile distribution.

  10. Ground-water geology of the coastal zone, Long Beach-Santa Ana area, California

    Science.gov (United States)

    Poland, J.F.; Piper, A.M.

    1956-01-01

    This paper is the first chapter of a comprehensive report on the ground-water features in the southern part of the coastal plain in Los Angeles and Orange Counties, Calif., with special reference to the effectiveness of the so-called coastal barrier--the Newport-Inglewood structural zone--in restraining landwar,-1 movement of saline water. The coastal plain in Los Angeles and Orange Counties, which covers some 775 square miles, sustains a large urban and rural population, diverse industries, and intensive agricultural developments. The aggregate ground-water withdrawal in 1945 was about 400,000 acre-feet a year, an average of about 360 million gallons a day. The dominant land-form elements are a central lowland plain with tongues extending to the coast, bordering highlands and foothills, and a succession of low hills and mesas aligned northwestward along the coastal edge of the central low- land plain. These low hills and mesas are the land-surface expression of geologic structure in the Newport-Inglewood zone. The highland areas that border the inland edge of the coastal plain are of moderate altitude and relief; most of the ridge crests range from 1,400 to 2,500 feet in altitude, but Santiago Peak in the Santa Ana Mountains attains a height of 5,680 feet above sea level. From these highlands the land surface descends across foothills and aggraded alluvial aprons to the central lowland, Downey Plain, here defined as the surface formed by alluvial aggradation during the post-Pleistocene time of rising base level. The Newport-Inglewood belt of hills and plains (mesas) has a maximum relief of some 500 feet but is widely underlain at a depth of about 30 feet by a surface of marine plantation. As initially formed in late Pleistocene time that surface was largely a featureless plain. Thus the present land-surface forms within the Newport-Inglewood belt measure the earth deformation that has occurred there since late Pleistocene time and so are pertinent with respect to

  11. Hydrogeologic analysis of the saturated-zone ground-water system, under Yucca Mountain, Nevada

    Science.gov (United States)

    Fridrich, C. J.; Dudley, W. W.; Stuckless, J. S.

    1994-02-01

    Mountain, is largely replaced in the volcanic section by lavas in the area of the large gradient; (3) an analysis of the hydrogeology of the tuff section under Yucca Mountain indicates that transmissivity in the tuffs increases to the south; (4) a northeast-trending gravity low is present immediately south of the water-table decline; (5) units in the lower part of the volcanic section are 50-100% thicker in the area of the gravity low than to the north and south. The abrupt stratigraphic thickening into the area of the gravity low indicates that the low represents a buried graben with its northern bounding fault centered beneath the abrupt water-table decline. These geologic features of the zone of large gradient under Yucca Mountain suggest two possible hydrogeologic models. First, the northern bounding fault of the buried graben may provide a highly permeable pathway (a drain) through the brittle lavas in the lower part of the volcanic section under northern Yucca Mountain. The drain would allow flow from the tuff aquifer north of the decline to be captured by the deep carbonate aquifer, resulting in the heat-flow low, the abrupt water-table decline, and the transition to a very small hydraulic gradient. Alternatively, the northern bounding fault of the buried graben may be the effective northern limit of the tuff aquifer under Yucca Mountain because the permeability in the tuffs north of the fault may have been diminished by hydrothermal alteration. In this second model, the large gradient marks the point where the small southward flow of water through the altered volcanic rocks to the north abruptly drops into the tuff aquifer. In either case, heads in the tuff aquifer in the area of very small gradient may be regulated partly by upward flow from the deep carbonate aquifer. This upward flow under southern Yucca Mountain is indicated by linear thermal highs along fault zones, by ground-water isotopic data suggesting inmixing of waters from the deep carbonate aquifer

  12. Indentation tectonics in the accretionary wedge of middle Manila Trench

    Institute of Scientific and Technical Information of China (English)

    LI Jiabiao; JIN Xianglong; RUAN Aiguo; WU Shimin; WU Ziyin; LIU Jianhua

    2004-01-01

    Based on the multibeam morpho-tectonic analysis of the Manila Trench accretionary wedge and its indentation tectonics and the contrasting researches with other geological and geophysical data, three tectonic zones of the wedge are established, faulting features, tectonic distribution and stress mechanism for the indentation tectonicsareanalyzed,oblique subduction along Manila Trench with convergent stress of NW55. Is presented, and the relationship of the ceasing of Eastern Subbasin spreading of South China Sea Basin to the formation of subduction zone of Manila Trench is discussed. By the model analysis and regional research, it is found that the seamount subduction along Manila Trenchoes not lead to the erosion of the accretionary wedge and the oblique subduction actually is a NWWtrending obducfion of Luzon micro-plate that results from the NWW-trending displacement of the Philippine Sea plate.

  13. Identification Of Ground Water Potential Zones In Tamil Nadu By Remote Sensing And GIS Technique

    Directory of Open Access Journals (Sweden)

    T. Subramani

    2014-12-01

    Full Text Available A case study was conducted to find out the groundwater potential zones in Salem, Erode and Namakkal districts, Tamil Nadu, India with an aerial extent of 360.60 km2 . The thematic maps such as geology, geomorphology, soil hydrological group, land use / land cover and drainage map were prepared for the study area. The Digital Elevation Model (DEM has been generated from the 10 m interval contour lines (which is derived from SOI, Toposheet 1:25000 scale and obtained the slope (% of the study area. The groundwater potential zones were obtained by overlaying all the thematic maps in terms of weighted overlay methods using the spatial analysis tool in Arc GIS 9.3. During weighted overlay analysis, the ranking has been given for each individual parameter of each thematic map and weights were assigned according to the influence such as soil −25%, geomorphology − 25%, land use/land cover −25%, slope − 15%, lineament − 5% and drainage / streams − 5% and find out the potential zones in terms of good, moderate and poor zones with the area of 49.70 km2 , 261.61 km2 and 46.04 km2 respectively. The potential zone wise study area was overlaid with village boundary map and the village wise groundwater potential zones with three categories such as good, moderate and poor zones were obtained. This GIS based output result was validated by conducting field survey by randomly selecting wells in different villages using GPS instruments. The coordinates of each well location were obtained by GPS and plotted in the GIS platform and it was clearly shown that the well coordinates were exactly seated with the classified zones.

  14. Surface Geophysical Measurements for Locating and Mapping Ice-Wedges

    DEFF Research Database (Denmark)

    Ingeman-Nielsen, Thomas; Tomaskovicova, Sonia; Larsen, S.H.

    2012-01-01

    With the presently observed trend of permafrost warming and degradation, the development and availability of effective tools to locate and map ice-rich soils and massive ground ice is of increasing importance. This paper presents a geophysical study of an area with polygonal landforms in order...... to test the applicability of DC electrical resistivity tomography (ERT) and Ground Penetrating Radar (GPR) to identifying and mapping ice-wedge occurrences. The site is located in Central West Greenland, and the ice-wedges are found in a permafrozen peat soil with an active layer of about 30 cm. ERT...... and GPR measurements give a coherent interpretation of possible ice-wedge locations, and active layer probing show a tendency for larger thaw depth in the major trench systems consistent with a significant temperature (at 10 cm depth) increase in these trenches identified by thermal profiling. Three...

  15. Devonian lacustrine shore zone architecture: giving perspective to cliff exposures with ground penetrating radar

    DEFF Research Database (Denmark)

    Andrews, Steven D.; Moreau, Julien; Archer, Stuart

    of these units. The cycles are on average 16-m-thick and comprise deep lake, perennial lake and playa facies. The shore zone facies reaches 2 to 3.5 m in thickness and is found within the playa facies. On the exposures, the shore zone facies seems to be aggrading with most of the layers apparently subhorizontal...... occurred over a wide area as the lake margin migrated back and forth, and gradually transgressed. Continued transgression forced fluvial systems back towards the basin margin....

  16. Devonian lacustrine shore zone architecture: giving perspective to cliff exposures with ground penetrating radar

    DEFF Research Database (Denmark)

    Andrews, Steven D.; Moreau, Julien; Archer, Stuart

    . However, this depositional environment ought to be relatively dynamic with sand body migration and erosions. In addition, along the coastal cliffs, the exposures are mainly on the same strike direction. To better understand the peculiar shore zone system, we carried out very high resolution sedimentary...

  17. Site response zones and short-period earthquake ground motion projections for the Las Vegas Basin

    Indian Academy of Sciences (India)

    Barbara Luke; Ying Liu

    2008-11-01

    A deterministic seismic hazard analysis was conducted to address the effect of local soil conditions on earthquake-induced strong ground motion in the Las Vegas Basin, Nevada (US). Using a large geological and geotechnical database, two response units were defined: a fine-grained unit, predominantly clay; and a coarse-grained unit, predominantly gravel. A moderate number of high-quality shallow shear wave velocity measurements were collected from which characteristic shear wave velocity profiles were developed for each response unit. An equivalent-linear one-dimensional site response model was used. The model was calibrated using a basin-wide, small-strain ground motion database. Calibration tests showed that ground motion projections become increasingly conservative with increasing ground-motion amplitude. Projections were overconservative for the coarsegrained response unit, likely due to the sparseness of the velocity database. For the earthquake response analyses, historical ground motions were used to model characteristic ‘bedrock’ motion for earthquakes on 10 faults judged to be critical. Response spectral envelopes were generated for each unit through Monte-Carlo simulations. For the fine-grained response unit, 95th percentile peak ground acceleration, peak spectral acceleration and predominant period were 310 cm/s2, 1100cm/s2, and 0.29 s, respectively. With respect to codified design spectra, projections are lower at short periods and higher at long periods. Projections of peak spectral accelerations for the coarsegrained response unit, were more than double that of codified spectra; however, they are believed to be overconservative. Near-fault effects and basin-edge effects, though potentially important, were not considered in these analyses.

  18. Numerical Modeling of Two-Dimensional Temperature Dynamics Across Ice-Wedge Polygons

    Science.gov (United States)

    Garayshin, Viacheslav V.

    The ice wedges on the North Slope of Alaska have been forming for many millennia, when the ground cracked and the cracks were filled with snowmelt water. The infiltrated water then became frozen and turned into ice. When the annual and summer air temperatures become higher, the depth of the active layer increases. A deeper seasonal thawing may cause melting of ice wedges from their tops. Consequently, the ground starts to settle and a trough begins to form above the ice wedge. The forming trough creates a local temperature anomaly in the surrounding ground, and the permafrost located immediately under the trough starts degrading further. Once the trough is formed, the winter snow cover becomes deeper at the trough area further degrading the permafrost. In this thesis we present a computational approach to study the seasonal temperature dynamics of the ground surrounding an ice wedge and ground subsidence associated with ice wedge degradation. A thermo-mechanical model of the ice wedge based on principles of macroscopic thermodynamics and continuum mechanics was developed and will be presented. The model includes heat conduction and quasi-static mechanical equilibrium equations, a visco-elastic rheology for ground deformation, and an empirical formula which relates unfrozen water content to temperature. The complete system is reduced to a computationally convenient set of coupled equations for temperature, ground displacement and ground porosity in a two-dimensional domain. A finite element method and an implicit scheme in time were utilized to construct a non-linear system of equations, which was solved iteratively. The model employs temperature and moisture content data collected from a field experiment at the Next-Generation Ecosystem Experiments (NGEE) sites in Barrow, Alaska. The model describes seasonal dynamics of temperature and the long-term ground motion near the ice wedges and helps to explain destabilization of the ice wedges north of Alaska's Brooks

  19. High resolution imaging of vadose zone transport using surface and crosswell ground penetrating radar methods

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kenneth H.; Kowalsky, Mike B.; Peterson, John E.

    2002-11-05

    To effectively clean up many contaminated sites there is a need for information on heterogeneities at scales ranging from one centimeter to tens of meters, as these features can alter contaminant transport significantly. At the Department of Energy's Hanford, Washington site heterogeneities of interest can range from localized phenomena such as silt or gravel lenses, fractures, clastic dikes, to large-scale lithologic discontinuities. In the vadose zone it is critical to understand the parameters controlling flow. These features have been suspected of leading to funneling and fingering, additional physical mechanisms that could alter and possibly accelerate the transport of contaminants to underlying groundwater. For example, it has been observed from the studies to date that over relatively short distances there are heterogeneities in the physical structure of the porous medium and structural differences between repacked soil cores and the field site from which the materials initially came (Raymond and Shdo, 1966). Analysis of cores taken from the vadose zone (i.e., soil surface to water table) has been useful in identifying localized zones of contamination. Unfortunately, these analyses are sparse (limited to a few boreholes) and extremely expensive. The high levels of radioactivity at many of the contaminated sites increase drilling and sample costs and analysis time. Cost of drilling and core analysis for the SX tank farm has exceeded $1M per borehole (50 meter deep) for sampling. The inability to track highly mobile species through the vadose zone highlights an important need: the need for methods to describe the complete vadose zone plume and to determine processes controlling accelerated contamination of groundwater at Hanford. A combination of surface and crosswell (i.e. borehole) geophysical measurements is one means to provide this information. The main questions addressed with the radar methods in this study are: (1) What parts of the vadose zone

  20. Decollement controls on pro versus retro wedge deformation in mountain belts

    Science.gov (United States)

    Grool, Arjan; Huismans, Ritske S.; Ford, Mary

    2017-04-01

    Pyrenees, the decollement is missing in the model's retro-wedge, the required convergence would be reduced to 180 km. Assuming deformation localizes along the path of least resistance, meaning a force balance exists between the pro- and retro-wedge, anything that changes the force required to deform one side of the orogen will have direct consequences for the other side as the strain distribution adjusts. In our models a viscous decollement enables the sedimentary cover of the pro-wedge to be transported into the pro-foredeep, increasing the force required for pro-wedge frontal accretion and thus promoting shortening in the retro-wedge. In models with no decollement in the retro-wedge, higher friction along existing crustal shear zones will accelerate formation of a new, more external shear zone. This mechanism alone cannot explain frontal accretion in the retro-wedge after only 145 km of convergence, meaning other factors such as more pre-existing extensional shear zones may also play a role in the Eastern Pyrenees.

  1. Zoning of the territory of Russia by the effectiveness of low-potential heat of the ground and atmospheric air for heating buildings

    Science.gov (United States)

    Vasilyev, G. P.; Kolesova, M. V.; Gornov, V. F.; Yurchenko, I. A.

    2016-06-01

    The article represents the results of researches to zone the territory of Russia and Europe division into districts of by efficiency of using for the heat supply of buildings of low-potential thermal energy of ground and free air and their combination. While modeling the heat regime of geothermal HPS in climatic conditions of different regions of the territory of Russia, the influence of the long-term extraction of geothermal heat energy on the ground heat regime has been taken into account as well as the influence of phase transitions of pore moisture in ground on the efficiency of operation of geothermal heat-pump heat-supply systems. Also considered were the sinking of temperatures of ground massif by long-term extraction of the heat energy from the ground as calculation parameters of the heat energy from the ground, and as calculation parameters of ground massif temperatures.

  2. Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology

    Science.gov (United States)

    Liljedahl, Anna K.; Boike, Julia; Daanen, Ronald P.; Fedorov, Alexander N.; Frost, Gerald V.; Grosse, Guido; Hinzman, Larry D.; Iijma, Yoshihiro; Jorgenson, Janet C.; Matveyeva, Nadya; Necsoiu, Marius; Raynolds, Martha K.; Romanovsky, Vladimir E.; Schulla, Jörg; Tape, Ken D.; Walker, Donald A.; Wilson, Cathy J.; Yabuki, Hironori; Zona, Donatella

    2016-04-01

    Ice wedges are common features of the subsurface in permafrost regions. They develop by repeated frost cracking and ice vein growth over hundreds to thousands of years. Ice-wedge formation causes the archetypal polygonal patterns seen in tundra across the Arctic landscape. Here we use field and remote sensing observations to document polygon succession due to ice-wedge degradation and trough development in ten Arctic localities over sub-decadal timescales. Initial thaw drains polygon centres and forms disconnected troughs that hold isolated ponds. Continued ice-wedge melting leads to increased trough connectivity and an overall draining of the landscape. We find that melting at the tops of ice wedges over recent decades and subsequent decimetre-scale ground subsidence is a widespread Arctic phenomenon. Although permafrost temperatures have been increasing gradually, we find that ice-wedge degradation is occurring on sub-decadal timescales. Our hydrological model simulations show that advanced ice-wedge degradation can significantly alter the water balance of lowland tundra by reducing inundation and increasing runoff, in particular due to changes in snow distribution as troughs form. We predict that ice-wedge degradation and the hydrological changes associated with the resulting differential ground subsidence will expand and amplify in rapidly warming permafrost regions.

  3. Caldecott 4th bore tunnel project: influence of ground water flows and inflows triggered by tectonic fault zones?

    Science.gov (United States)

    Neuhuber, G.; G. Neuhuber1, W. Klary1, A. Nitschke1, B. Thapa2, Chris Risden3, T. Crampton4, D. Zerga5

    2011-12-01

    nearly perpendicular, separating different geological units were expected along the 4th Bore alignment. This paper will describe encountered ground conditions adjacent to the fault contact where rock conditions are influenced to an extent of 5ft to 85ft from the contact. This paper will also compare the anticipated inflow of 55gpm within 100ft of the top heading excavation and fault zones inflow rates up to 110gpm to the actual measured maximum inflow into the tunnel of150gpm away from fault zones to a maximum inflow between 60gpm and 100gpm near fault zones. In presence of fault zones the water inflow is significant lower than expected and in absence of fault zones higher inflow rates as expected were measured. This paper will discuss the influence of fault zones on the water inflow - or are rock properties and lithology more significant?

  4. Biomechanical effects of lateral and medial wedge insoles on unilateral weight bearing.

    Science.gov (United States)

    Sawada, Tomonori; Kito, Nobuhiro; Yukimune, Masaki; Tokuda, Kazuki; Tanimoto, Kenji; Anan, Masaya; Takahashi, Makoto; Shinkoda, Koichi

    2016-01-01

    [Purpose] Lateral wedge insoles reduce the peak external knee adduction moment and are advocated for patients with knee osteoarthritis. However, some patients demonstrate adverse biomechanical effects with treatment. In this study, we examined the immediate effects of lateral and medial wedge insoles under unilateral weight bearing. [Subjects and Methods] Thirty healthy young adults participated in this study. The subjects were assessed by using the foot posture index, and were divided into three groups: normal foot, pronated foot, and supinated foot groups. The knee adduction moment and knee-ground reaction force lever arm under the studied conditions were measured by using a three-dimensional motion capture system and force plates. [Results] In the normal and pronated groups, the change in knee adduction moment significantly decreased under the lateral wedge insole condition compared with the medial wedge insole condition. In the normal group, the change in the knee-ground reaction force lever arm also significantly decreased under the lateral wedge insole condition than under the medial wedge insole condition. [Conclusion] Lateral wedge insoles significantly reduced the knee adduction moment and knee-ground reaction force lever arm during unilateral weight bearing in subjects with normal feet, and the biomechanical effects varied according to individual foot alignment.

  5. Portal dosimetry in wedged beams

    NARCIS (Netherlands)

    Spreeuw, H.; Rozendaal, R.; Camargo, P.; Mans, A.; Wendling, M.; Olaciregui-Ruiz, I.; Sonke, J.J.; Herk, M. van; Mijnheer, B.

    2015-01-01

    Portal dosimetry using electronic portal imaging devices (EPIDs) is often applied to verify high-energy photon beam treatments. Due to the change in photon energy spectrum, the resulting dose values are, however, not very accurate in the case of wedged beams if the pixel-to-dose conversion for the s

  6. Wedge wetting by electrolyte solutions

    Science.gov (United States)

    Mußotter, Maximilian; Bier, Markus

    2017-09-01

    The wetting of a charged wedgelike wall by an electrolyte solution is investigated by means of classical density functional theory. As in other studies on wedge wetting, this geometry is considered as the most simple deviation from a planar substrate, and it serves as a first step toward more complex confinements of fluids. By focusing on fluids containing ions and surface charges, features of real systems are covered that are not accessible within the vast majority of previous theoretical studies concentrating on simple fluids in contact with uncharged wedges. In particular, the filling transition of charged wedges is necessarily of first order, because wetting transitions of charged substrates are of first order and the barrier in the effective interface potential persists below the wetting transition of a planar wall; hence, critical filling transitions are not expected to occur for ionic systems. The dependence of the critical opening angle on the surface charge, as well as the dependence of the filling height, of the wedge adsorption, and of the line tension on the opening angle and on the surface charge are analyzed in detail.

  7. Immediate and 1 week effects of laterally wedge insoles on gait biomechanics in healthy females.

    Science.gov (United States)

    Weinhandl, Joshua T; Sudheimer, Sarah E; Van Lunen, Bonnie L; Stewart, Kimberly; Hoch, Matthew C

    2016-03-01

    It is estimated that approximately 45% of the U.S. population will develop knee osteoarthritis, a disease that creates significant economic burdens in both direct and indirect costs. Laterally wedged insoles have been frequently recommended to reduce knee abduction moments and to manage knee osteoarthritis. However, it remains unknown whether the lateral wedge will reduce knee abduction moments over a prolonged period of time. Thus, the purposes of this study were to (1) examine the immediate effects of a laterally wedged insole in individuals normally aligned knees and (2) determine prolonged effects after the insole was worn for 1 week. Gait analysis was performed on ten women with and without a laterally wedged insole. After participants wore the wedges for a week, a second gait analysis was performed with and without the insole. The wedged insole did not affect peak knee abduction moment, although there was a significant increase in knee abduction angular impulse after wearing the insoles for 1 week. Furthermore, there was a significant increase in vertical ground reaction force at the instance of peak knee abduction moment with the wedges. While the laterally wedged insole used in the current study did not alter knee abduction moments as expected, other studies have shown alterations. Future studies should also examine a longer acclimation period, the influence of gait speed, and the effect of different shoe types with the insole.

  8. Ground-based Transit Observation of the Habitable-zone Super-Earth K2-3d

    Science.gov (United States)

    Fukui, Akihiko; Livingston, John; Narita, Norio; Hirano, Teruyuki; Onitsuka, Masahiro; Ryu, Tsuguru; Kusakabe, Nobuhiko

    2016-12-01

    We report the first ground-based transit observation of K2-3d, a 1.5 R ⊕ planet supposedly within the habitable zone around a bright M-dwarf host star, using the Okayama 188 cm telescope and the multi(grz)-band imager MuSCAT. Although the depth of the transit (0.7 mmag) is smaller than the photometric precisions (1.2, 0.9, and 1.2 mmag per 60 s for the g, r, and z bands, respectively), we marginally but consistently identify the transit signal in all three bands, by taking advantage of the transit parameters from K2, and by introducing a novel technique that leverages multi-band information to reduce the systematics caused by second-order extinction. We also revisit previously analyzed Spitzer transit observations of K2-3d to investigate the possibility of systematic offsets in transit timing, and find that all the timing data can be explained well by a linear ephemeris. We revise the orbital period of K2-3d to be 44.55612 ± 0.00021 days, which corrects the predicted transit times for 2019, i.e., the era of the James Webb Space Telescope, by ∼80 minutes. Our observation demonstrates that (1) even ground-based, 2 m class telescopes can play an important role in refining the transit ephemeris of small-sized, long-period planets, and (2) a multi-band imager is useful to reduce the systematics of atmospheric origin, in particular for bluer bands and for observations conducted at low-altitude observatories.

  9. Zoning of the Territory of Russia According to the Efficiency of the Use of Low-Grade Ground Heat for Heating

    Directory of Open Access Journals (Sweden)

    Vasilyev G.P.

    2015-01-01

    Full Text Available This paper reports the results of study on the effectiveness of using low-grade ground heat in heat pump systems under the climatic conditions of Russia. The study was performed using the software package “INSOLAR.GSHP.12”, which simulates the non-stationary thermal conditions of ground source heat pumps (GSHPs over several years of operation. The paper presents the results of the zoning of the territory of Russia according to the effectiveness of using low-grade ground heat in heat pump systems. The zoning was performed with consideration of the decrease of the soil temperatures over several years of heat collection system operation. The soil temperatures expected on the fifth year of operation were considered to be the design temperatures. The described study was performed with the financial support of the Ministry of Education and Science of Russia. Contract ID RFMEFI57914X0026.

  10. Ground-based Transit Observation of the Habitable-zone super-Earth K2-3d

    CERN Document Server

    Fukui, Akihiko; Narita, Norio; Hirano, Teruyuki; Onitsuka, Masahiro; Ryu, Tsuguru; Kusakabe, Nobuhiko

    2016-01-01

    We report the first ground-based transit observation of K2-3d, a 1.5 R_Earth planet supposedly within the habitable zone around a bright M-dwarf host star, using the Okayama 188-cm telescope and the multi(grz)-band imager MuSCAT. Although the depth of the transit (0.7 mmag) is smaller than the photometric precisions (1.2, 0.9, and 1.2 mmag per 60 s for g, r, and z bands, respectively), we marginally but consistently identify the transit signal in all three bands, by taking advantage of the transit parameters from K2, and by introducing a novel technique that leverages multi-band information to reduce the systematics caused by second-order extinction. We also revisit previously analyzed Spitzer transit observations of K2-3d to investigate the possibility of systematic offsets in transit timing, and find that all the timing data can be explained well by a linear ephemeris. We revise the orbital period of K2-3d to be 44.55612 \\pm 0.00021 days, which corrects the predicted transit times in 2019, i.e., the JWST er...

  11. Stark effect in a wedge-shaped quantum box

    CERN Document Server

    Reyes-Esqueda, J A; Castillo-Mussot, M; Vazquez, G J; Reyes-Esqueda, Jorge-Alejandro; Mendoza, Carlos I.; Castillo-Mussot, Marcelo del; Vazquez, Gerardo J.

    2005-01-01

    The effect of an external applied electric field on the electronic ground state energy of a quantum box with a geometry defined by a wedge is studied by carrying out a variational calculation. This geometry could be used as an approximation for a tip of a cantilever of an atomic force microscope. We study theoretically the Stark effect as function of the parameters of the wedge: its diameter, angular aperture and thickness; as well as function of the intensity of the external electric field applied along the axis of the wedge in both directions; pushing the carrier towards the wider or the narrower parts. A confining electronic effect, which is sharper as the wedge dimensions are smaller, is clearly observed for the first case. Besides, the sign of the Stark shift changes when the angular aperture is changed from small angles to angles theta>pi. For the opposite field, the electronic confinement for large diameters is very small and it is also observed that the Stark shift is almost independent with respect t...

  12. Contact process in a wedge

    CERN Document Server

    Cox, J Theodore; Schinazi, Rinaldo B

    2009-01-01

    We prove that the supercritical one-dimensional contact process survives in certain wedge-like space-time regions, and that when it survives it couples with the unrestricted contact process started from its upper invariant measure. As an application we show that a type of weak coexistence is possible in the nearest-neighbor ``grass-bushes-trees'' successional model introduced in Durrett and Swindle (1991).

  13. Isolating active orogenic wedge deformation in the southern Subandes of Bolivia

    Science.gov (United States)

    Weiss, Jonathan R.; Brooks, Benjamin A.; Foster, James H.; Bevis, Michael; Echalar, Arturo; Caccamise, Dana; Heck, Jacob; Kendrick, Eric; Ahlgren, Kevin; Raleigh, David; Smalley, Robert; Vergani, Gustavo

    2016-08-01

    A new GPS-derived surface velocity field for the central Andean backarc permits an assessment of orogenic wedge deformation across the southern Subandes of Bolivia, where recent studies suggest that great earthquakes (>Mw 8) are possible. We find that the backarc is not isolated from the main plate boundary seismic cycle. Rather, signals from subduction zone earthquakes contaminate the velocity field at distances greater than 800 km from the Chile trench. Two new wedge-crossing velocity profiles, corrected for seasonal and earthquake affects, reveal distinct regions that reflect (1) locking of the main plate boundary across the high Andes, (2) the location of and loading rate at the back of orogenic wedge, and (3) an east flank velocity gradient indicative of décollement locking beneath the Subandes. Modeling of the Subandean portions of the profiles indicates along-strike variations in the décollement locked width (WL) and wedge loading rate; the northern wedge décollement has a WL of ~100 km while accumulating slip at a rate of ~14 mm/yr, whereas the southern wedge has a WL of ~61 km and a slip rate of ~7 mm/yr. When compared to Quaternary estimates of geologic shortening and evidence for Holocene internal wedge deformation, the new GPS-derived wedge loading rates may indicate that the southern wedge is experiencing a phase of thickening via reactivation of preexisting internal structures. In contrast, we suspect that the northern wedge is undergoing an accretion or widening phase primarily via slip on relatively young thrust-front faults.

  14. Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions.

    Science.gov (United States)

    Böhlke, J K; O'Connell, Michael E; Prestegaard, Karen L

    2007-01-01

    Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses of ground water, macropore discharge, and stream water. The ground water flow system exhibits vertical stratification of hydraulic properties and redox conditions, with sub-horizontal boundaries that extend beneath the field and adjacent riparian forest. Below the minimum water table position, ground water age gradients indicate low recharge rates (2-5 cm yr(-1)) and long residence times (years to decades), whereas the transient ground water wedge between the maximum and minimum water table positions has a relatively short residence time (months to years), partly because of an upward increase in hydraulic conductivity. Oxygen reduction and denitrification in recharging ground waters are coupled with pyrite oxidation near the minimum water table elevation in a mottled weathering zone in Tertiary marine glauconitic sediments. The incised stream had high nitrate concentrations during high flow conditions when much of the ground water was transmitted rapidly across the riparian zone in a shallow oxic aquifer wedge with abundant outflow macropores, and low nitrate concentrations during low flow conditions when the oxic wedge was smaller and stream discharge was dominated by upwelling from the deeper denitrified parts of the aquifer. Results from this and similar studies illustrate the importance of near-stream geomorphology and subsurface geology as controls of riparian zone function and delivery of nitrate to streams in agricultural watersheds.

  15. Modes of continental extension in a crustal wedge

    KAUST Repository

    Wu, Guangliang

    2015-07-01

    © 2015 Elsevier B.V. We ran numerical experiments of the extension of a crustal wedge as an approximation to extension in an orogenic belt or a continental margin. We study the effects of the strength of the lower crust and of a weak mid-crustal shear zone on the resulting extension styles. A weak mid-crustal shear zone effectively decouples upper crustal extension from lower crustal flow. Without the mid-crustal shear zone, the degree of coupling between the upper and the lower crust increases and extension of the whole crust tends to focus on the thickest part of the wedge. We identify three distinct modes of extension determined by the strength of the lower crust, which are characterized by 1) localized, asymmetric crustal exhumation in a single massif when the lower crust is weak, 2) the formation of rolling-hinge normal faults and the exhumation of lower crust in multiple core complexes with an intermediate strength lower crust, and 3) distributed domino faulting over the weak mid-crustal shear zone when the lower crust is strong. A frictionally stronger mid-crustal shear zone does not change the overall model behaviors but extension occurred over multiple rolling-hinges. The 3 modes of extension share characteristics similar to geological models proposed to explain the formation of metamorphic core complexes: 1) the crustal flow model for the weak lower crust, 2) the rolling-hinge and crustal flow models when the lower crust is intermediate and 3) the flexural uplift model when the lower crust is strong. Finally we show that the intensity of decoupling between the far field extension and lower crustal flow driven by the regional pressure gradient in the wedge control the overall style of extension in the models.

  16. Modes of continental extension in a crustal wedge

    Science.gov (United States)

    Wu, Guangliang; Lavier, Luc L.; Choi, Eunseo

    2015-07-01

    We ran numerical experiments of the extension of a crustal wedge as an approximation to extension in an orogenic belt or a continental margin. We study the effects of the strength of the lower crust and of a weak mid-crustal shear zone on the resulting extension styles. A weak mid-crustal shear zone effectively decouples upper crustal extension from lower crustal flow. Without the mid-crustal shear zone, the degree of coupling between the upper and the lower crust increases and extension of the whole crust tends to focus on the thickest part of the wedge. We identify three distinct modes of extension determined by the strength of the lower crust, which are characterized by 1) localized, asymmetric crustal exhumation in a single massif when the lower crust is weak, 2) the formation of rolling-hinge normal faults and the exhumation of lower crust in multiple core complexes with an intermediate strength lower crust, and 3) distributed domino faulting over the weak mid-crustal shear zone when the lower crust is strong. A frictionally stronger mid-crustal shear zone does not change the overall model behaviors but extension occurred over multiple rolling-hinges. The 3 modes of extension share characteristics similar to geological models proposed to explain the formation of metamorphic core complexes: 1) the crustal flow model for the weak lower crust, 2) the rolling-hinge and crustal flow models when the lower crust is intermediate and 3) the flexural uplift model when the lower crust is strong. Finally we show that the intensity of decoupling between the far field extension and lower crustal flow driven by the regional pressure gradient in the wedge control the overall style of extension in the models.

  17. Spatial and temporal distribution of deformation at the front of the Andean orogenic wedge in Bolivia and implications for incremental wedge evolution

    Science.gov (United States)

    Weiss, J. R.; Brooks, B. A.; Vergani, G.; Arrowsmith, R.

    2012-12-01

    There is no consensus regarding how orogenic wedges accommodate deformation over seismo-tectonic timescales. Results from the Himalaya and Taiwan suggest differing mechanisms including localized deformation along a single wedge-front structure and distributed shortening across multiple structures respectively. Here we provide the first detailed constraints on the distribution and timing of deformation at the front of the Andean orogenic wedge using industry acquired seismic reflection data from the ~500-km-long thin-skinned fold-and-thrust belt of the Bolivian Subandes (BSA). Almost no information exists on the recent history of BSA wedge-front deformation despite the presence of multiple ~10-m-high topographic scarps on Holocene surfaces and a recent analysis of the GPS-derived velocity field, which suggests the frontal Mandeyapecua thrust fault system (MTFS) is capable of >Mw 8 earthquakes. We use stratigraphic relationships across fault-related folds to depict the onset of deformation for the complete suite of structures comprising the MTFS. For each structure we determine the uncertainty in timing using an envelope of seismic velocity models from ~70 well-logs and published Quaternary sedimentation rates for the region. We further explore fault geometry and fault slip parameters associated with the displacement field of seismic reflection horizons using elastic dislocation theory. Our analyses reveal the presence of at least eight distinct fault segments comprising the MTFS, including previously unrecognized subsurface thrust faults that have been active since ~1 Ma. Shortening rates are generally higher across the younger, northern portion of the fault system but across-strike, in a ~50-km-wide zone from west to east, no distinct pattern of deformation migration exists. We estimate the percentage of whole-wedge deformation accommodated by wedge-front structures using our new fault slip rates combined with the wedge-loading rate of ~10 mm/yr and place our

  18. Fine-scale delineation of the location of and relative ground shaking within the San Andreas Fault zone at San Andreas Lake, San Mateo County, California

    Science.gov (United States)

    Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Prentice, C.S.; Sickler, R.R.

    2013-01-01

    extensional stresses on built structures within the fault zone. Such differential movement and resulting distortion of built structures appear to have occurred between fault traces at the gatewell near the southern end of San Andreas Lake during the 1906 San Francisco earthquake (Schussler, 1906). In addition to the three fault traces within the main 1906 surface rupture zone, our data indicate at least one additional fault trace (or zone) about 80 meters northeast of the main 1906 surface rupture zone. Because ground shaking also can damage structures, we used fault-zone guided waves to investigate ground shaking within the fault zones relative to ground shaking outside the fault zones. Peak ground velocity (PGV) measurements from our guided-wave study indicate that ground shaking is greater at each of the surface fault traces, varying with the frequency of the seismic data and the wave type (P versus S). S-wave PGV increases by as much as 5–6 times at the fault traces relative to areas outside the fault zone, and P-wave PGV increases by as much as 3–10 times. Assuming shaking increases linearly with increasing earthquake magnitude, these data suggest strong shaking may pose a significant hazard to built structures that extend across the fault traces. Similarly complex fault structures likely underlie other strike-slip faults (such as the Hayward, Calaveras, and Silver Creek Faults) that intersect structures of the water delivery system, and these fault structures similarly should be investigated.

  19. Geometry and kinematics of extensional structural wedges

    Science.gov (United States)

    Gui, Baoling; He, Dengfa; Zhang, Yongsheng; Sun, Yanpeng; Huang, Jingyi; Zhang, Wenjun

    2017-03-01

    Structural wedges in the compressive environment have been recognized and studied in different locations. However, extension structural wedges are less well-understood. Based on the normal fault-bend folding theory and inclined shear model, this paper quantitatively analyses deformations related to extensional structural wedges and builds a series of geometric models for them. An extensional structural wedge is a fault-block held by two or more normal faults, the action of which would fold its overlying strata. Extensional structural wedges of different shapes will lead to different deformation results for the overlying strata, and this paper illustrates both the triangular and quadrangular wedges and their related deformations. This paper also discusses differences between the extensional structural wedges and the normal fault-bend-folding. By analysing two seismic sections from Langfang-Gu'an Sag, East China, this paper provides two natural examples of the triangular and quadrangular extensional structural wedges, where the models can reasonably explain the overlying distinct highs and lows without obvious faults. The establishment of a geometric model of extensional structural wedges can provide reference and theoretical bases for future quantitative analysis of deformations in the extensional environment.

  20. Characterization of lake water and ground water movement in the littoral zone of Williams Lake, a closed-basin lake in North central Minnesota

    Science.gov (United States)

    Schuster, P.F.; Reddy, M.M.; LaBaugh, J.W.; Parkhurst, R.S.; Rosenberry, D.O.; Winter, T.C.; Antweiler, R.C.; Dean, W.E.

    2003-01-01

    Williams Lake, Minnesota is a closed-basin lake that is a flow-through system with respect to ground water. Ground-water input represents half of the annual water input and most of the chemical input to the lake. Chemical budgets indicate that the lake is a sink for calcium, yet surficial sediments contain little calcium carbonate. Sediment pore-water samplers (peepers) were used to characterize solute fluxes at the lake-water-ground-water interface in the littoral zone and resolve the apparent disparity between the chemical budget and sediment data. Pore-water depth profiles of the stable isotopes ??18O and ??2H were non-linear where ground water seeped into the lake, with a sharp transition from lake-water values to ground-water values in the top 10 cm of sediment. These data indicate that advective inflow to the lake is the primary mechanism for solute flux from ground water. Linear interstitial velocities determined from ??2H profiles (316 to 528 cm/yr) were consistent with velocities determined independently from water budget data and sediment porosity (366 cm/yr). Stable isotope profiles were generally linear where water flowed out of the lake into ground water. However, calcium profiles were not linear in the same area and varied in response to input of calcium carbonate from the littoral zone and subsequent dissolution. The comparison of pore-water calcium profiles to pore-water stable isotope profiles indicate calcium is not conservative. Based on the previous understanding that 40-50 % of the calcium in Williams Lake is retained, the pore-water profiles indicate aquatic plants in the littoral zone are recycling the retained portion of calcium. The difference between the pore-water depth profiles of calcium and ??18O and ??2H demonstrate the importance of using stable isotopes to evaluate flow direction and source through the lake-water-ground-water interface and evaluate mechanisms controlling the chemical balance of lakes. Published in 2003 by John Wiley

  1. Parental arc magma compositions dominantly controlled by mantle-wedge thermal structure

    Science.gov (United States)

    Turner, Stephen J.; Langmuir, Charles H.; Katz, Richard F.; Dungan, Michael A.; Escrig, Stéphane

    2016-10-01

    The processes that lead to the fourfold variation in arc-averaged compositions of mafic arc lavas remain controversial. Control by the mantle-wedge thermal structure is supported by chemical correlations with the thickness of the underlying arc crust, which affects the thermal state of the wedge. Control by down-going slab temperature is supported by correlations with the slab thermal parameter. The Chilean Southern Volcanic Zone provides a test of these hypotheses. Here we use chemical data to demonstrate that the Southern Volcanic Zone and global arc averages define the same chemical trends, both among elements and between elements and crustal thickness. But in contrast to the global arc system, the Southern Volcanic Zone is built on crust of variable thickness with a constant slab thermal parameter. This natural experiment, along with a set of numerical simulations, shows that global arc compositional variability is dominated by different extents of melting that are controlled by the thermal structure of the mantle wedge. Slab temperatures play a subordinate role. Variations in the subducting slab's fluid flux and sediment compositions, as well as mantle-wedge heterogeneities, produce second-order effects that are manifested as distinctive trace element and isotopic signatures; these can be more clearly elucidated once the importance of wedge thermal structure is recognized.

  2. Ice Particle Impacts on a Moving Wedge

    Science.gov (United States)

    Vargas, Mario; Struk, Peter M.; Kreeger, Richard E.; Palacios, Jose; Iyer, Kaushik A.; Gold, Robert E.

    2014-01-01

    This work presents the results of an experimental study of ice particle impacts on a moving wedge. The experiment was conducted in the Adverse Environment Rotor Test Stand (AERTS) facility located at Penn State University. The wedge was placed at the tip of a rotating blade. Ice particles shot from a pressure gun intercepted the moving wedge and impacted it at a location along its circular path. The upward velocity of the ice particles varied from 7 to 12 meters per second. Wedge velocities were varied from 0 to 120 meters per second. Wedge angles tested were 0 deg, 30 deg, 45 deg, and 60 deg. High speed imaging combined with backlighting captured the impact allowing observation of the effect of velocity and wedge angle on the impact and the post-impact fragment behavior. It was found that the pressure gun and the rotating wedge could be synchronized to consistently obtain ice particle impacts on the target wedge. It was observed that the number of fragments increase with the normal component of the impact velocity. Particle fragments ejected immediately after impact showed velocities higher than the impact velocity. The results followed the major qualitative features observed by other researchers for hailstone impacts, even though the reduced scale size of the particles used in the present experiment as compared to hailstones was 4:1.

  3. Component testing of a ground based gas turbine steam cooled rich-burn primary zone combustor for emissions control of nitrogeneous fuels

    Science.gov (United States)

    Schultz, D. F.

    1986-01-01

    This effort summarizes the work performed on a steam cooled, rich-burn primary zone, variable geometry combustor designed for combustion of nitrogeneous fuels such as heavy oils or synthetic crude oils. The steam cooling was employed to determine its feasibility and assess its usefulness as part of a ground based gas turbine bottoming cycle. Variable combustor geometry was employed to demonstrate its ability to control primary and secondary zone equivalence ratios and overall pressure drop. Both concepts proved to be highly successful in achieving their desired objectives. The steam cooling reduced peak liner temperatures to less than 800 K. This low temperature offers the potential of both long life and reduced use of strategic materials for liner fabrication. These degrees of variable geometry were successfully employed to control air flow distribution within the combustor. A variable blade angle axial flow air swirler was used to control primary zone air flow, while the secondary and tertiary zone air flows were controlled by rotating bands which regulated air flow to the secondary zone quench holes and the dilutions holes respectively.

  4. Water-saturated physical modeling of accretionary wedges

    Science.gov (United States)

    Yamada, Y.; Zhang, M.; Nakajima, H.; Driss, E.

    2005-12-01

    Accretionary wedges have been an important research target from view points of earthquake mechanism at the subduction zone, sediment deformation that is closely coupled with hydrology, and resource exploration such as methane hydrates. The knowledge obtained from the study may also be useful for site selection of geological disposal of hazardous materials including radioactive nuclear wastes, in coastal areas of tectonically unstable island arc systems like Japan. The wedges have been well-investigated with analogue models in particular sandbox experiments that typically use dry granular materials, thus the inter-granular pore space of the sandbox experiments is filled with air. In natural sediments, however, the pore space is filled with formation water and its pressure has special effects on structural development. In order to accurately simulate the in-situ conditions and to examine the effects of water on the deformation process of accretionary wedge, a new apparatus was recently constructed in AIST, Japan, to perform physical analog experiments of accretionary wedges under water-saturated condition. For comparisons, equivalent experiments with dry materials were also conducted. The physical properties of the materials were also measured with tri-axial compression tests to interpret the experimental observations. Preliminary results obtained from this study showed that the fundamental parameters on structural geometry, such as taper angle and fault spacing, can be correlated well in wet and dry experiments. These are also in good agreement with physical properties obtained by the tri-axial compression tests, suggesting that the internal friction coefficient decreases as the overburden pressure increases. In the under water models, buoyancy decreases apparent grain density and overburden pressure thus the internal friction coefficient also decreases. This also agrees with the structural geometry of the experimental results. These results suggest that under

  5. Ground-penetrating radar and electrical resistivity tomography for mapping bedrock topography and fracture zones: a case study in Viru-Nigula, NE Estonia

    Directory of Open Access Journals (Sweden)

    Ivo Sibul

    2017-06-01

    Full Text Available The Geological Base Map (GBM, presenting an elongated buried valley running beneath the Varudi bog, triggered the geophysical studies near Viru-Nigula borough in northeastern Estonia. After the Geological Survey of Estonia had compiled the GBM map set, the course and extent of the valley still remained indistinct. Principally the morphology of the Varudi valley had been determined just by one borehole characterizing the 30 m thick Quaternary succession within the valley. The thickness of Quaternary sediments is, however, just a few metres in adjacent boreholes. We used ground-penetrating radar and electrical resistivity tomography (ERT for acquiring extra knowledge about the extent and morphology of the Varudi structure. Ground-penetrating radar enabled us to specify the thickness and composition of Quaternary deposits, and to recognize dislocations of the bedrock blocks. As the radar images provided information on the topmost ~4 m only, ERT (Wenner and Wenner–Schlumberger arrays was applied to define deeper, down to 40 m, electrical resistivity anomalies. The ERT studies revealed two fracture zones where regular Ordovician carbonate beds have been crushed and replaced by Quaternary sediments. The Varudi valley coincides with the southern zone. Both fracture zones probably acted as groundwater flow channels and sediment pathways in the Late Pleistocene, and hence supported the creation of the Varudi bog.

  6. Formation of Microelement Composition and Hydrogeochemical Anomalous Zones of Ground-water of the Kama PreUrals Region

    Directory of Open Access Journals (Sweden)

    I. S. Kopylov

    2014-09-01

    Full Text Available The results of hydrogeochemical studies and groundwater mapping in the Kama PreUrals are given in the article. Analytical data (more than 2000 spectral analyses of water samples, mainly from the springs are analyzed. Regularities of distribution of the background values of basic geochemical parameters (macro – and microelements in groundwater has been studied. Hydrogeochemical particularities are revealed. Hydro-geochemical zoning was conducted and the geochemical anomalous zones were deter-mined. Studies provided for the first time an integrated assessment of microelements hydrogeochemistry of the Western Urals and the PreUrals at the regional level. A large number of hydrogeochemical anomalies are located on the territory of the Perm region. It was established that concentration for 18 elements exceeds a legislation admissible limit. The large anomalous zones are characteristic for high concentrations of Br, B, Ba, Mn, and Ti, but anomalies of Sb, Be, Cd, V, Cr, Ni, Pb, Sr, F, Zn, Co, Mo, and P are observed locally. Anomalies in the zone of active water exchange form 14 complex geochemical anomalous zones of areas from 2 000 up to 9 000 km2. The natural environments of formation of hydrogeochemical fields are the main factors of generation of the geochemical anomalies with predominant role of structural, tectonic conditions, and geodynamic (neotectonic activity. The major hydrogeochemical anomalies spatially coincide with litho-geochemical, geophysical anomalies, and geodynamic active zones.

  7. Simulations of Ground-Water Flow and Particle Pathline Analysis in the Zone of Contribution of a Public-Supply Well in Modesto, Eastern San Joaquin Valley, California

    Science.gov (United States)

    Burow, Karen R.; Jurgens, Bryant C.; Kauffman, Leon J.; Phillips, Steven P.; Dalgish, Barbara A.; Shelton, Jennifer L.

    2008-01-01

    Shallow ground water in the eastern San Joaquin Valley is affected by high nitrate and uranium concentrations and frequent detections of pesticides and volatile organic compounds (VOC), as a result of ground-water development and intensive agricultural and urban land use. A single public-supply well was selected for intensive study to evaluate the dominant processes affecting the vulnerability of public-supply wells in the Modesto area. A network of 23 monitoring wells was installed, and water and sediment samples were collected within the approximate zone of contribution of the public-supply well, to support a detailed analysis of physical and chemical conditions and processes affecting the water chemistry in the well. A three-dimensional, steady-state local ground-water-flow and transport model was developed to evaluate the age of ground water reaching the well and to evaluate the vulnerability of the well to nonpoint source input of nitrate and uranium. Particle tracking was used to compute pathlines and advective travel times in the ground-water flow model. The simulated ages of particles reaching the public-supply well ranged from 9 to 30,000 years, with a median of 54 years. The age of the ground water contributed to the public-supply well increased with depth below the water table. Measured nitrate concentrations, derived primarily from agricultural fertilizer, were highest (17 milligrams per liter) in shallow ground water and decreased with depth to background concentrations of less than 2 milligrams per liter in the deepest wells. Because the movement of water is predominantly downward as a result of ground-water development, and because geochemical conditions are generally oxic, high nitrate concentrations in shallow ground water are expected to continue moving downward without significant attenuation. Simulated long-term nitrate concentrations indicate that concentrations have peaked and will decrease in the public-supply well during the next 100 years

  8. Semi-infinite $q$-wedge construction of the level 2 Fock Space of $U_q(\\widehat{sl}_2)$

    CERN Document Server

    Petersen, J U H

    1997-01-01

    In this proceedings a particular example from \\cite{KMPY} (q-alg/9603025) is presented: the construction of the level 2 Fock space of $\\U_q(\\affsl{2})$. The generating ideal of the wedge relations is given and the wedge space defined. Normal ordering of wedges is defined in terms of the energy function. Normally ordered wedges form a base of the wedge space. The q-deformed Fock space is defined as the space of semi-infinite wedges with a finite number of vectors in the wedge product differing from a ground state sequence, and endowed with a separated q-adic topology . Normally ordered wedges form a base of the Fock space. The action of $\\U_q(\\affsl{2})$ on the Fock space converges in the q-adic topology. On the Fock space the action of bosons, which commute with the $\\U_q(\\affsl{2})$-action, also converges in the q-adic topology. Hence follows the decomposition of the Fock space into irreducible $\\U_q(\\affsl{2})$-modules.

  9. Numerical Analyses of Bearing Capacity of Deep-Embedded Large-Diameter Cylindrical Structure on Soft Ground Against Lateral Loads

    Institute of Scientific and Technical Information of China (English)

    LUAN Mao-tian; FAN Qing-lai

    2006-01-01

    Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotropic soft ground. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in the passive zone or two wedges in both active and passive zones near the mudline, depending on the separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge, and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method by virtue of the general-purpose FEM software ABAQUS, in which the soil is assumed to obey tie Hill's criterion of yield. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. For the K0-consolidated ground of clays typically with anisotropic undrained strength property, it is indicated through a parametric study that limit analysis without consideration of anisotropy of soil overestimates the lateral ultimate bearing capacity of a deeply-embedded cylindrical structure in soft ground in a certain condition.

  10. Ground Shaking and Earthquake Engineering Aspects of the M 8.8 Chile Earthquake of 2010 - Applications to Cascadia and Other Subduction Zones (Invited)

    Science.gov (United States)

    Cassidy, J. F.; Boroschek, R.; Ventura, C.; Huffman, S.

    2010-12-01

    The M 8.8 Maule, Chile earthquake of February 27, 2010 was the fifth largest earthquake ever recorded by seismographs and provides a rare opportunity to compare strong shaking observations with earthquake rupture and damage patterns. This subduction earthquake was caused by up to 13 m of eastward slip of the Nazca plate beneath the South American plate. The rupture zone extended nearly 600 km along the Chile coast and covered the most populated region of the country - extending from south of Concepcion to just south of Valpraiso (near the latitude of Santiago). As this is the type of earthquake that is expected along the Cascadia subduction zone of western Canada and the U.S., and given that modern building codes and construction styles in Chile and Cascadia are very similar, the Canadian Association of Earthquake Engineers sent a team of 10 engineers and a seismologist to the earthquake zone to learn from this earthquake. In this presentation we focus on sites where strong ground shaking was recorded (the data available to date range from about 0.1g to 0.66g). The recorded waveforms showed strong shaking for up to 2-3 minutes, with two distinct bursts of energy that may correspond to two large asperities that ruptured. At many locations, particularly along the coast, the recorded shaking levels exceeded code values, especially at longer periods (~ 1 second and longer). There was significant damage to older hospitals and schools. Twenty-five hospitals were severely damaged (17 collapsed, 8 repairable) and in the Maule region, 45% of the hospital beds were lost. More than 2500 schools were damaged and more than 780,000 students were affected. Of about 12,000 bridges in Chile, only 40 were damaged, 20 severely (many of these were newer overpasses). Modern high-rise buildings, in general, did very well. Of the 10,000 3-storey or higher buildings constructed since 1985, only 4 collapsed, and 50-150 were badly damaged. This clearly demonstrates the importance of modern

  11. Optical dating of relict sand wedges and composite-wedge pseudomorphs in Flanders, Belgium

    DEFF Research Database (Denmark)

    Buylaert, Jan-Pieter; Ghysels, Günther; Murray, Andrew S.;

    2009-01-01

    We report on quartz Optically Stimulated Luminescence (OSL) dating of the infill of 14 relict sand wedges and composite-wedge pseudomorphs at 5 different sites in Flanders, Belgium. A laboratory dose recovery test indicates that the single-aliquot regenerative-dose (SAR) procedure is suitable...... appear to have been commonplace in Flanders during the Late Pleniglacial (Oxygen Isotope Stage 2; OIS2); more specifically, around the Last Glacial Maximum (LGM, similar to 21 kyr ago) and the transition period between the LGM and the start of the Lateglacial (similar to 15 kyr ago). Optical dating...... at one site has revealed two significantly older wedge levels, the younger inset into the older; the younger wedge has an age of 36 +/- 4 kyr (Middle Pleniglacial; OIS3), the older wedge 129 +/- 11 kyr, which points to formation during the Late Saalian (OIS6). Our OSL ages of the wedges and host...

  12. Climate control based on temperature measurement in the animal-occupied zone of a pig room with ground channel ventilation

    NARCIS (Netherlands)

    Wagenberg, van A.V.; Aerts, J.M.; Brecht, van A.; Vranken, E.; Leroy, T.; Berckmans, D.

    2005-01-01

    It is known that there can be a significant temperature difference between the position of the climate controller sensor (room temperature) and the animal-occupied zone (AOZ) in a pig room. This study explores the advantages of using AOZ temperature in climate control. The objectives were: (1) to ev

  13. Physical models of spall zone ground motions and the determination of spatial decay rates. Los Alamos Source Region Project

    Energy Technology Data Exchange (ETDEWEB)

    Stump, B.W. [Southern Methodist Univ., Dallas, TX (United States). Dept. of Geological Sciences; Weaver, T.A. [Los Alamos National Lab., NM (United States)

    1992-01-24

    Spall, the tensile failure of near-surface layers, which is observed above contained explosions, has been identified as a possible secondary seismic source contributing to teleseismic and regional signals. The relative importance of this secondary source can be constrained if the motion field in the spall zone is characterized. Spall zone motions from nuclear explosions detonated above the water table at Pahute Mesa are analyzed to develop these models. Acceleration, velocity, displacement, and dwell time measurements are made from gauges placed directly above the explosion, most often at the free surface. Decay of peak motions are strongly affected by the free surface with little change in amplitude out to a free surface range of 100 m/kt{sup l/3} followed by rapid decay beyond. Free surface interactions are assessed with first-order elastic spherical wave calculations that match observed peak velocity decays. These results indicate that the spall zone motions may be strongly affected by the scaled depth of burial of the explosion. Spall zone velocities, displacements and dwell times are compared for consistency with a gravitational model. The data is in agreement with the functional form of theoretical models although observed displacements may be as much as a factor of two to four greater than the model predicts for observed velocities and dwell times. These differences may reflect the continuous nature of the spall process and/or the role of material strength in these phenomena.

  14. Use of Wedge Absorbers in MICE

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Summers, D. [Univ. of Mississippi, Oxford, MS (United States); Mohayai, T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); IIT, Chicago, IL (United States); Snopok, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); IIT, Chicago, IL (United States); Rogers, C. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL)

    2017-03-01

    Wedge absorbers are needed to obtain longitudinal cooling in ionization cooling. They also can be used to obtain emittance exchanges between longitudinal and transverse phase space. There can be large exchanges in emittance, even with single wedges. In the present note we explore the use of wedge absorbers in the MICE experiment to obtain transverse–longitudinal emittance exchanges within present and future operational conditions. The same wedge can be used to explore “direct” and “reverse” emittance exchange dynamics, where direct indicates a configuration that reduces momentum spread and reverse is a configuration that increases momentum spread. Analytical estimated and ICOOL and G4BeamLine simulations of the exchanges at MICE parameters are presented. Large exchanges can be obtained in both reverse and direct configurations.

  15. Benchmarking numerical models of brittle thrust wedges

    NARCIS (Netherlands)

    Buiter, Susanne J H; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric|info:eu-repo/dai/nl/270177493; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher

    2016-01-01

    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the

  16. A specially curved wedge for eliminating wedge angle effect in unsteady shock reflection

    Science.gov (United States)

    Wang, He; Zhai, Zhigang; Luo, Xisheng; Yang, Jiming; Lu, Xiyun

    2017-08-01

    A curved wedge with a specific shape is designed and manufactured to guarantee the wedge angle unvaried during the cylindrically converging shock moving along the wedge. Thus the variation of the wedge angle caused by the wedge will be eliminated in unsteady shock reflection. Different initial wedge angles are considered to observe regular reflection and Mach reflection. When Mach reflection occurs, it is found that direct Mach reflection is persisted over the wedge without wave pattern transitions, which differs from our previous work with varied wedge angles [Zhang et al. "Reflection of cylindrical converging shock wave over a plane wedge," Phys. Fluids 28, 086101 (2016)]. Moreover, the Mach stem is nearly straight when the wedge angle is relatively large, and the trajectory of triple point can be well predicted by three-shock theory. It is believed that the straight Mach stem results from the coupling effect of the converging shock and the convexly curved wedge, which exert opposite effects on the Mach stem curvature. As the wedge angle reduces, the three-shock theory prediction deviates from the present results owing to the curved Mach stem. Stronger vortices are produced near the wall, which are caused by the interaction of two shear layers, and whether the stronger vortices will be generated near the wall depends on the reflection number of the shock wave over the tube wall and wedge. The length of disturbed shock front in the Mach reflection is found to increase nonlinearly due to the unsteady feature of the flow. The growth rate of length reduces as the shock converges because of the geometrical contraction effect. Further the lengths of the Mach stem and the disturbed shock front are compared, and the results show that although the difference exists between them, both of them show a similar variation tendency. Compared with our previous work with varied wedge angles, the variation of the wedge angle has great effects on the Mach stem length and wave

  17. Long-range hybrid wedge plasmonic waveguide.

    Science.gov (United States)

    Zhang, Zhonglai; Wang, Jian

    2014-11-03

    We design a novel long-range hybrid wedge plasmonic (LRHWP) waveguide composed of two identical dielectric nanowires symmetrically placed on two opposed wedges of a diamond shaped metal wire. With strong coupling between the dielectric nanowire mode and long-range surface plasmon polariton (SPP) mode, both deep subwavelength mode confinement and low propagation loss are achieved. On one hand, when compared to the previous long-range hybrid SPP waveguide, LRHWP waveguide can achieve smaller mode size with similar propagation length; on the other hand, when compared to the previous hybrid wedge SPP waveguide, LRHWP waveguide can provide an order of magnitude longer propagation length with similar level of mode confinement. The designed LRHWP waveguide also features an overall advantage of one-order improvement of Figure of Merit. We further evaluate in detail the impacts of possible practical fabrication imperfections on the mode properties. The obtained results of mode properties show that the proposed LRHWP waveguide with an optimized wedge tip angle of 140 degree is fairly tolerant to practical fabrication errors in geometry parameters such as misalignment in the horizontal direction, asymmetry in the vertical direction, variation of wedge tip angle, tilt or rotation of metal wire, and variation of wedge tip curvature radius.

  18. Integrating geospatial and ground geophysical information as guidelines for groundwater potential zones in hard rock terrains of south India.

    Science.gov (United States)

    Rashid, Mehnaz; Lone, Mahjoor Ahmad; Ahmed, Shakeel

    2012-08-01

    The increasing demand of water has brought tremendous pressure on groundwater resources in the regions were groundwater is prime source of water. The objective of this study was to explore groundwater potential zones in Maheshwaram watershed of Andhra Pradesh, India with semi-arid climatic condition and hard rock granitic terrain. GIS-based modelling was used to integrate remote sensing and geophysical data to delineate groundwater potential zones. In the present study, Indian Remote Sensing RESOURCESAT-1, Linear Imaging Self-Scanner (LISS-4) digital data, ASTER digital elevation model and vertical electrical sounding data along with other data sets were analysed to generate various thematic maps, viz., geomorphology, land use/land cover, geology, lineament density, soil, drainage density, slope, aquifer resistivity and aquifer thickness. Based on this integrated approach, the groundwater availability in the watershed was classified into four categories, viz. very good, good, moderate and poor. The results reveal that the modelling assessment method proposed in this study is an effective tool for deciphering groundwater potential zones for proper planning and management of groundwater resources in diverse hydrogeological terrains.

  19. Effect of fuel zoning and fuel nozzle design on pollution emissions at ground idle conditions for a double-annular ram-induction combustor

    Science.gov (United States)

    Clements, T. R.

    1973-01-01

    An exhaust emission survey was conducted on a double-annular ram induction combustor at simulated ground idle conditions. The combustor was designed for a large augmented turbofan engine capable of sustained flight speeds up to Mach 3.0. The emission levels of total hydrocarbon (THC), carbon monoxide, carbon dioxide, and nitric oxide were measured. The effects of fuel zoning, fuel nozzle design, and operating conditions (inlet temperature and reference Mach number) on the level of these emissions were determined. At an overall combustor fuel/air ratio of 0.007, fuel zoning reduced THC emissions by a factor of 5 to 1. The reduction in THC emissions is attributed to the increase in local fuel/air ratio provided by the fuel zoning. An alternative method of increasing fuel/air ratio would be to operate with larger-than-normal compressor overboard bleed; however, analysis on this method indicated an increase in idle fuel consumption of 20 percent. The use of air-atomizing nozzles reduced the THC emissions by 2 to 1.

  20. Magmatism significantly alters the thermal structure of the wedge

    Science.gov (United States)

    Rees Jones, D. W.; Katz, R. F.; Rudge, J. F.; Tian, M.

    2016-12-01

    The temperature structure of the mantle wedge is typically modelled as a balance between thermal diffusion and advection by the solid mantle [e.g., 1]. The thermal state of the wedge promotes melting and melt transport in the natural system, but the thermal consequences of these processes have been neglected from previous models. We show that advective transport of sensible and latent heat by liquid magma can locally alter the temperature structure from canonical models by up to 200K. Liquids are liberated from the subducting slab by de-volatilization reactions. They trigger melting and become silicic en route to the surface, where they cause arc volcanism. These liquids transport heat advectively, and consume or supply latent heat as they melt or freeze. To analyse these effects, we parameterise melting in the presence of volatile species. We combine this with a one-dimensional "melting-column model," previously used to understand mid-ocean ridge volcanism. Our calculations highlight the thermal and chemical response to melt transport across the mantle wedge. Finally, we solve two-dimensional geodynamic models with a prescribed slab flux [2]. These models allow us to identify the most thermally significant fluxes of melt in the system. Perturbations of 200K are found at the base of the overriding lithosphere. This thermal signature of melt migration should be considered when interpreting heat flow, petrologic and seismic data [e.g., 3]. Such a thermal perturbation is likely to affect the chemistry of arc volcanoes, the solid mantle flow and, perhaps, the location of the volcanos themselves [4]. [1] van Keken, P. E., Currie, C., King, S. D., Behn, M. D., Cagnioncle, A., He, J., et al. (2008). A community benchmark for subduction zone modeling. PEPI, doi:10.1016/j.pepi.2008.04.015 [2] Wilson, C. R., Spiegelman, M., van Keken, P. E., & Hacker, B. R. (2014). Fluid flow in subduction zones: The role of solid rheology and compaction pressure. EPSL, doi:10.1016/j

  1. Studying wedge factors and beam profiles for physical and enhanced dynamic wedges

    Directory of Open Access Journals (Sweden)

    Ahmad Misbah

    2010-01-01

    Full Text Available This study was designed to investigate variation in Varian′s Physical and Enhanced Dynamic Wedge Factors (WF as a function of depth and field size. The profiles for physical wedges (PWs and enhanced dynamic wedges (EDWs were also measured using LDA-99 array and compared for confirmation of EDW angles at different depths and field sizes. WF measurements were performed in water phantom using cylindrical 0.66 cc ionization chamber. WF was measured by taking the ratio of wedge and open field ionization data. A normalized wedge factor (NWF was introduced to circumvent large differences between wedge factors for different wedge angles. A strong linear dependence of PW Factor (PWF with depth was observed. Maximum variation of 8.9% and 4.1% was observed for 60° PW with depth at 6 and 15 MV beams respectively. The variation in EDW Factor (EDWF with depth was almost negligible and less than two per cent. The highest variation in PWF as a function of field size was 4.1% and 3.4% for thicker wedge (60° at 6 and 15 MV beams respectively and decreases with decreasing wedge angle. EDWF shows strong field size dependence and significant variation was observed for all wedges at both photon energies. Differences in profiles between PW and EDW were observed on toe and heel sides. These differences were dominant for larger fields, shallow depths, thicker wedges and low energy beam. The study indicated that ignoring depth and field size dependence of WF may result in under/over dose to the patient especially doing manual point dose calculation.

  2. Stress singularity in a top of composite wedge with internal functionally graded material

    Directory of Open Access Journals (Sweden)

    Victor V. Tikhomirov

    2015-10-01

    Full Text Available The antiplane problem of the composite wedge consisting of two homogeneous external wedge-shaped areas and an intermediate zone of the interphase is studied. The interphase material is assumed functionally graded. It is shown that the problem in each area is harmonic within the quadratic law of inhomogeneity of the material in the transverse direction. The influence of the interphase on the stress state at the top of the wedge is analyzed. As compared to the ideal contact of external materials, the presence of the interphase leads both to decrease and increase in the singularity exponent. Moreover, the stress asymptotic may have two singular terms for some values of the composite parameters.

  3. Pervasive seismic wave reflectivity and metasomatism of the Tonga mantle wedge.

    Science.gov (United States)

    Zheng, Yingcai; Lay, Thorne; Flanagan, Megan P; Williams, Quentin

    2007-05-11

    Subduction zones play critical roles in the recycling of oceanic lithosphere and the generation of continental crust. Seismic imaging can reveal structures associated with key dynamic processes occurring in the upper-mantle wedge above the sinking oceanic slab. Three-dimensional images of reflecting interfaces throughout the upper-mantle wedge above the subducting Tonga slab were obtained by migration of teleseismic recordings of underside P- and S-wave reflections. Laterally continuous weak reflectors with tens of kilometers of topography were detected at depths near 90, 125, 200, 250, 300, 330, 390, 410, and 450 kilometers. P- and S-wave impedances decreased at the 330-kilometer and 450-kilometer reflectors, and S-wave impedance decreased near 200 kilometers in the vicinity of the slab and near 390 kilometers, just above the global 410-kilometer increase. The pervasive seismic reflectivity results from phase transitions and compositional zonation associated with extensive metasomatism involving slab-derived fluids rising through the wedge.

  4. Rainfall induced groundwater mound in wedge-shaped promontories: The Strack-Chernyshov model revisited

    Science.gov (United States)

    Kacimov, A. R.; Kayumov, I. R.; Al-Maktoumi, A.

    2016-11-01

    An analytical solution to the Poisson equation governing Strack's discharge potential (squared thickness of a saturated zone in an unconfined aquifer) is obtained in a wedge-shaped domain with given head boundary conditions on the wedge sides (specified water level in an open water body around a porous promontory). The discharge vector components, maximum elevation of the water table in promontory vertical cross-sections, quantity of groundwater seeping through segments of the wedge sides, the volume of fresh groundwater in the mound are found. For acute angles, the solution to the problem is non-unique and specification of the behaviour at infinity is needed. A "basic" solution is distinguished, which minimizes the water table height above a horizontal bedrock. MODFLOW simulations are carried out in a finite triangular island and compare solutions with a constant-head, no-flow and "basic" boundary condition on one side of the triangle. Far from the tip of an infinite-size promontory one has to be cautious with truncation of the simulated flow domains and imposing corresponding boundary conditions. For a right and obtuse wedge angles, there are no positive solutions for the case of constant accretion on the water table. In a particular case of a confined rigid wedge-shaped aquifer and incompressible fluid, from an explicit solution to the Laplace equation for the hydraulic head with arbitrary time-space varying boundary conditions along the promontory rays, essentially 2-D transient Darcian flows within the wedge are computed. They illustrate that surface water waves on the promontory boundaries can generate strong Darcian waves inside the porous wedge. Evaporation from the water table and sea-water intruded interface (rather than a horizontal bed) are straightforward generalizations for the Poissonian Strack potential.

  5. Subduction of fracture zones

    Science.gov (United States)

    Constantin Manea, Vlad; Gerya, Taras; Manea, Marina; Zhu, Guizhi; Leeman, William

    2013-04-01

    Since Wilson proposed in 1965 the existence of a new class of faults on the ocean floor, namely transform faults, the geodynamic effects and importance of fracture zone subduction is still little studied. It is known that oceanic plates are characterized by numerous fracture zones, and some of them have the potential to transport into subduction zones large volumes of water-rich serpentinite, providing a fertile water source for magma generated in subduction-related arc volcanoes. In most previous geodynamic studies, subducting plates are considered to be homogeneous, and there is no clear indication how the subduction of a fracture zone influences the melting pattern in the mantle wedge and the slab-derived fluids distribution in the subarc mantle. Here we show that subduction of serpentinized fracture zones plays a significant role in distribution of melt and fluids in the mantle wedge above the slab. Using high-resolution tree-dimensional coupled petrological-termomechanical simulations of subduction, we show that fluids, including melts and water, vary dramatically in the region where a serpentinized fracture zone enters into subduction. Our models show that substantial hydration and partial melting tend to concentrate where fracture zones are being subducted, creating favorable conditions for partially molten hydrous plumes to develop. These results are consistent with the along-arc variability in magma source compositions and processes in several regions, as the Aleutian Arc, the Cascades, the Southern Mexican Volcanic Arc, and the Andean Southern Volcanic Zone.

  6. Status of understanding of the saturated-zone ground-water flow system at Yucca Mountain, Nevada, as of 1995

    Energy Technology Data Exchange (ETDEWEB)

    Luckey, R.R.; Tucci, P.; Faunt, C.C.; Ervin, E.M. [and others

    1996-12-31

    Yucca Mountain, which is being studied extensively because it is a potential site for a high-level radioactive-waste repository, consists of a thick sequence of volcanic rocks of Tertiary age that are underlain, at least to the southeast, by carbonate rocks of Paleozoic age. Stratigraphic units important to the hydrology of the area include the alluvium, pyroclastic rocks of Miocene age (the Timber Mountain Group; the Paintbrush Group; the Calico Hills Formation; the Crater Flat Group; the Lithic Ridge Tuff; and older tuffs, flows, and lavas beneath the Lithic Ridge Tuff), and sedimentary rocks of Paleozoic age. The saturated zone generally occurs in the Calico Hills Formation and stratigraphically lower units. The saturated zone is divided into three aquifers and two confining units. The flow system at Yucca Mountain is part of the Alkali Flat-Furnace Creek subbasin of the Death Valley groundwater basin. Variations in the gradients of the potentiometric surface provided the basis for subdividing the Yucca Mountain area into zones of: (1) large hydraulic gradient where potentiometric levels change at least 300 meters in a few kilometers; (2) moderate hydraulic gradient where potentiometric levels change about 45 meters in a few kilometers; and (3) small hydraulic gradient where potentiometric levels change only about 2 meters in several kilometers. Vertical hydraulic gradients were measured in only a few boreholes around Yucca Mountain; most boreholes had little change in potentiometric levels with depth. Limited hydraulic testing of boreholes in the Yucca Mountain area indicated that the range in transmissivity was more than 2 to 3 orders of magnitude in a particular hydrogeologic unit, and that the average values for the individual hydrogeologic units generally differed by about 1 order of magnitude. The upper volcanic aquifer seems to be the most permeable hydrogeologic unit, but this conclusion was based on exceedingly limited data.

  7. Seismic evidence for a cold serpentinized mantle wedge beneath Mount St Helens.

    Science.gov (United States)

    Hansen, S M; Schmandt, B; Levander, A; Kiser, E; Vidale, J E; Abers, G A; Creager, K C

    2016-11-01

    Mount St Helens is the most active volcano within the Cascade arc; however, its location is unusual because it lies 50 km west of the main axis of arc volcanism. Subduction zone thermal models indicate that the down-going slab is decoupled from the overriding mantle wedge beneath the forearc, resulting in a cold mantle wedge that is unlikely to generate melt. Consequently, the forearc location of Mount St Helens raises questions regarding the extent of the cold mantle wedge and the source region of melts that are responsible for volcanism. Here using, high-resolution active-source seismic data, we show that Mount St Helens sits atop a sharp lateral boundary in Moho reflectivity. Weak-to-absent PmP reflections to the west are attributed to serpentinite in the mantle-wedge, which requires a cold hydrated mantle wedge beneath Mount St Helens (<∼700 °C). These results suggest that the melt source region lies east towards Mount Adams.

  8. The role of subducting bathymetric highs on the oceanic crust to deformation of accretionary wedge and earthquake segmentation in the Java forearc

    Science.gov (United States)

    Singh, S. C.; Mukti, M.; Deighton, I.

    2014-12-01

    Stratigraphic and structural observations of newly acquired seismic reflection data along the offshore south Java reveal the structural style of deformation along the forearc and the role of subducting bathymetric highs to the morphology of the forearc region. The forearc region can be divided in to two major structural units: accretionary wedge and forearc and forearc basin where a backthrust marks the boundary between the accretionary wedge and the forearc basin sediments. The continuous compression in the subduction zone has induced younger landward-vergent folds and thrusts within the seaward margin of the forearc basin sediments, which together with the backthrust is referred as the Offshore South Java Fault Zone (OSJFZ), representing the growth of the accretionary wedge farther landward. Seaward-vergent imbricated thrusts have deformed the sediments in the accretionary wedge younging seaward, and have developed fold-thrust belts in the accretionary wedge toward trench. Together with the backthrusts, these seaward-vergent thrusts characterize the growth of accretionary wedge in South of Java trench. Based on these new results, we suggest that accretionary wedge mechanic is not the first order factor in shaping the morphology of the accretionary wedge complex. Instead the subducting bathymetric highs play the main role in shaping the forearc that are manifested in the uplift of the forearc high and intense deformation along the OSJFZ. These subducting highs also induce compression within the accretionary sediments, evident from landward deflection of the subduction front at the trench and inner part of accretionary wedge in the seaward margin of the forearc basin. Intense deformation is also observed on the seaward portion of the accretionary wedge area where the bathymetric highs subducted. We suggest that these subducted bathymetric features define the segment boundaries for megathrust earthquakes, and hence reducing the maximum size of the earthquakes in the

  9. Three-dimensional simulations of ground motions in the Seattle region for earthquakes in the Seattle fault zone

    Science.gov (United States)

    Frankel, A.; Stephenson, W.

    2000-01-01

    We used the 3D finite-difference method to model observed seismograms of two earthquakes (ML 4.9 and 3.5) in the Seattle region and to simulate ground motions for hypothetical M 6.5 and M 5.0 earthquakes on the Seattle fault, for periods greater than 2 sec. A 3D velocity model of the Seattle Basin was constructed from studies that analyzed seismic-reflection surveys, borehole logs, and gravity and aeromagnetic data. The observations and the simulations highlight the importance of the Seattle Basin on long-period ground motions. For earthquakes occurring just south of the basin, the edge of the basin and the variation of the thickness of the Quaternary deposits in the basin produce much larger surface waves than expected from flat-layered models. The data consist of seismograms recorded by instruments deployed in Seattle by the USGS and the University of Washington (UW). The 3D simulation reproduces the peak amplitude and duration of most of the seismograms of the June 1997 Bremerton event (ML 4.9) recorded in Seattle. We found the focal mechanism for this event that best fits the observed seismograms in Seattle by combining Green's functions determined from the 3D simulations for the six fundamental moment couples. The February 1997 event (ML 3.5) to the south of the Seattle Basin exhibits a large surface-wave arrival at UW whose amplitude is matched by the synthetics in our 3D velocity model, for a source depth of 9 km. The M 6.5 simulations incorporated a fractal slip distribution on the fault plane. These simulations produced the largest ground motions in an area that includes downtown Seattle. This is mainly caused by rupture directed up dip toward downtown, radiation pattern of the source, and the turning of S waves by the velocity gradient in the Seattle basin. Another area of high ground motion is located about 13 km north of the fault and is caused by an increase in the amplitude of higher-mode Rayleigh waves caused by the thinning of the Quaternary

  10. Wedged tibial components for total knee arthroplasty.

    Science.gov (United States)

    Jeffery, R S; Orton, M A; Denham, R A

    1994-08-01

    Severe coronal deformity of the knee is frequently associated with erosion of one tibial condyle. This can cause problems with fixation and alignment during total knee arthroplasty. If the tibia is cut to the level of the more worn side, valuable bone is sacrificed; if the less worn side is chosen, the deficiency must be filled with bone--graft, cement, or a prosthesis. Tibial components with an integral polyethylene wedge on the undersurface were introduced in 1980 for use in patients with a bony deficit on one tibial condyle. The authors believe that the Denham prosthesis (Biomet, Wales, U.K.) was the first knee arthroplasty to offer such spacers. Twenty-six patients with preoperative varus deformity in whom a wedged component was used were compared with 29 historic control subjects. None of the wedged components loosened after a median follow-up period of 8 years compared with loosening in five of the control subjects (P = .01). In three of the control subjects a fractured triangle of cement was present on the radiographs. Use of the wedges was not accompanied by an improvement in postoperative alignment. The authors conclude that the wedges resulted in improved fixation that was independent of postoperative alignment.

  11. Long polymers near wedges and cones

    Science.gov (United States)

    Hammer, Yosi; Kantor, Yacov

    2015-12-01

    We perform a Monte Carlo study of N -step self-avoiding walks, attached to the corner of an impenetrable wedge in two dimensions (d =2 ), or the tip of an impenetrable cone in d =3 , of sizes ranging up to N =106 steps. We find that the critical exponent γα, which determines the dependence of the number of available conformations on N for a cone or wedge with opening angle α , is in good agreement with the theory for d =2 . We study the end-point distribution of the walks in the allowed space and find similarities to the known behavior of random walks (ideal polymers) in the same geometry. For example, the ratio between the mean square end-to-end distances of a polymer near the cone or wedge and a polymer in free space depends linearly on γα, as is known for ideal polymers. We show that the end-point distribution of polymers attached to a wedge does not separate into a product of angular and radial functions, as it does for ideal polymers in the same geometry. The angular dependence of the end position of polymers near the wedge differs from theoretical predictions.

  12. Commissioning, clinical implementation and quality assurance of Siemen's Virtual Wedge.

    Science.gov (United States)

    Rathee, S; Kwok, C B; MacGillivray, C; Mirzaei, M

    1999-01-01

    This report presents the results of commissioning, clinical implementation and quality assurance of Siemens Virtual Wedge. Our measurements show that: (1) wedge factors are within 2% of unity, (2) percentage depth doses are within 1% of open beam data, and (3) wedged beam profiles can be modeled similarly to a physical wedge and follow a well defined equation to facilitate modeling of an arbitrary wedge angle. The gantry angle dependence of wedge profiles is similar to open beam profiles. The output of wedged fields is linear with delivered monitor units within 1%. Quality assurance results indicate the wedge profiles are very stable over time. Day to day variations of two points measured along the wedge gradient direction are within 1.5%.

  13. Proximal first metatarsal opening wedge osteotomy: geometric analysis on saw bone models.

    Science.gov (United States)

    Kugan, R; Currall, V A; Johal, P; Clark, C I C

    2015-03-01

    For hallux valgus correction, distal first metatarsal osteotomy is generally used for minor to moderate deformities, diaphyseal osteotomy for moderate deformities and basal osteotomy or arthrodesis for severe deformities. With the advent of locking plates, there has been renewed interest in opening wedge basal osteotomy. We undertook this study in order to understand the power and limitations of this osteotomy. Proximal opening wedge osteotomies were performed on saw bone models in four orientations, with three different wedge sizes: (1) perpendicular to the ground (PG); (2) perpendicular to the shaft (PS); (3) perpendicular to shaft with 30° declination (DEC); (4) 30° oblique (OB). Pre- and post-osteotomy measurements were made of axial and plantar translation and inter-metatarsal angle. Plantar translation and intermetatarsal angle correction increased with increasing wedge size. The DEC osteotomy produced the greatest increase in length of metatarsal shaft, while the PS osteotomy gave the least. The most plantar translation was achieved with the DEC osteotomy. Overall, the PS osteotomy gave the largest correction of the intermetatarsal angle. Although there are several published clinical case series of the proximal opening wedge osteotomy, this is the first study to fully evaluate its geometry. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Structure of turbulent wedges created by isolated surface roughness

    Science.gov (United States)

    Kuester, Matthew S.; White, Edward B.

    2016-04-01

    Isolated surface roughness in a laminar boundary layer can create a wedge of turbulence that spreads laterally into the surrounding laminar flow. Some recent studies have identified high- and low-speed streaks along the exterior of turbulent wedges. In this experiment, developing turbulent wedges are measured to observe the creation of these streaks. Naphthalene shear stress surface visualization and hotwire measurements are utilized to investigate the details of turbulent wedges created by cylinders in a laminar flat-plate boundary layer. Both the surface visualization and the hotwire measurements show high- and low-speed streaks in the wake of the cylinder that devolve into a turbulent wedge. The turbulent wedge spreading is associated with the emergence of these high- and low-speed streaks along the outside of the wedge. As the wedge evolves in the streamwise direction, these streaks persist inside of the core of the wedge, while new, lower amplitude streaks form along the outside of the wedge. Adding asymmetry to the cylinder moved the virtual origin closer to the roughness and increased the vortex shedding frequency, while adding small-scale roughness features did not strongly affect turbulent wedge development. Intermittency calculations additionally show the origin of the turbulent core inside of the wedge. The structure and spacing of the high-speed streaks along the extremities of the turbulent wedge give insight into the spreading angle of the turbulent wedge.

  15. Late Holocene stable-isotope based winter temperature records from ice wedges in the Northeast Siberian Arctic

    Science.gov (United States)

    Opel, Thomas; Meyer, Hanno; Laepple, Thomas; Dereviagin, Alexander Yu.

    2016-04-01

    The Arctic is currently undergoing an unprecedented warming. This highly dynamic response on changes in climate forcing and the global impact of the Arctic water, carbon and energy balances make the Arctic a key region to study past, recent and future climate changes. Recent proxy-based temperature reconstructions indicate a long-term cooling over the past about 8 millennia that is mainly related to a decrease in solar summer insolation and has been reversed only by the ongoing warming. Climate model results on the other hand show no significant change or even a slight warming over this period. This model-proxy data mismatch might be caused by a summer bias of the used climate proxies. Ice wedges may provide essential information on past winter temperatures for a comprehensive seasonal picture of Holocene Arctic climate variability. Polygonal ice wedges are a widespread permafrost feature in the Arctic tundra lowlands. Ice wedges form by the repeated filling of thermal contraction cracks with snow melt water, which quickly refreezes at subzero ground temperatures and forms ice veins. As the seasonality of frost cracking and infill is generally related to winter and spring, respectively, the isotopic composition of wedge ice is indicative of past climate conditions during the annual cold season (DJFMAM, hereafter referred to as winter). δ18O of ice is interpreted as proxy for regional surface air temperature. AMS radiocarbon dating of organic remains in ice-wedge samples provides age information to generate chronologies for single ice wedges as well as regionally stacked records with an up to centennial resolution. In this contribution we seek to summarize Holocene ice-wedge δ18O based temperature information from the Northeast Siberian Arctic. We strongly focus on own work in the Laptev Sea region but consider as well literature data from other regional study sites. We consider the stable-isotope composition of wedge ice, ice-wedge dating and chronological

  16. Short- and long-term deformation and the earthquake cycle in the southern Bolivia Subandes: Implications for orogenic wedge processes

    Science.gov (United States)

    Brooks, B. A.; Bevis, M. G.; Whipple, K. X.; Kendrick, E. C.; Smalley, R.; Arrowsmith, R.; Zapata, T.

    2009-12-01

    In the context of critical taper wedge mechanics, we analyze a new GPS-derived surface velocity field from the southern Subandean (SSA) range on the east flank of the central Andean Plateau. The SSA is one of the few active orogenic wedges located far enough from a plate boundary so that the geodetic signature of contractional processes may be isolated. We observe and model a strong strike-perpendicular surface velocity gradient as arising from the change in frictional behaviour of the SSA basal decollement from freely slipping to locked. The estimated width of the locked zone is ~130 km, a value that is significantly larger than in other similar wedges in Nepal or Taiwan and implies the SSA thrust front could host great (larger than M 8) intraplate thrust earthquakes. In support of this, topographic data (individual scarps and landslide scars) are consistent with the surface expression of the ~500 km long Mandeyepecua thrust fault resulting from large earthquake ruptures with long recurrence intervals. In comparison to other similar wedges (the northern Subandes, Nepal, and Taiwan) precipitation rates in the SSA are significantly lower and thus a wider orogenic wedge width is predicted by critical taper theory. We explore the hypothesis that the geodetically-determined width is equivalent to the orogenic wedge width by using earthquake scaling relations for individual faults and surface displacements predicted from decollement ruptures to model the velocity profile derived from published, sequentially restored balanced cross-sections in the region. Our work provides two new important insights on the interaction between climate and tectonics in orogenic wedges: 1) a drier climate favours increased size of potential thrust-front earthquakes by permitting the width of the active wedge to increase; 2) frictional variations on a decollement may be spatially persistent over geologic time-scales and so should be taken into account in surface process models of orogenic

  17. Modelling of Seismic Ground Motion in Santiago de Cuba City from Earthquakes in Oriente Fault Seismic Zone

    Science.gov (United States)

    Alvarez, L.; Panza, G. F.; Vaccari, F.; González, B. E.

    We present the results of complete P-SV and SH waves modelling, up to a maximum frequency of 1Hz, along two profiles in Santiago de Cuba city. The seismic sources are located in the depth range from 10 to 40km on the Oriente fault zone at distances of several tens of kilometres from the city. The calculation has been made by a hybrid method: Modal summation in the regional anelastic model (one-dimensional) where the source is buried, and finite differences in the local sedimentary anelastic models (two-dimensional). The analysis of the influence of the depth and of the distance of the source on the site effects shows that standard traditional methods, based on the deconvolution analysis of the rock outcrop motion, can lead to erroneous results.

  18. Explicit reconstruction of the entanglement wedge

    CERN Document Server

    Kim, Jung-Wook

    2016-01-01

    The problem of bulk locality, or how the boundary encodes the bulk in AdS/CFT, is still a subject of study today. One of the major issues that needs more elucidation is the problem of subregion duality; what information of the bulk a given boundary subregion encodes. Although proofs given by two teams of researchers, Dong, Harlow, and Wall and Bao, and Kim, state that the entanglement wedge of the bulk should be reconstructible from boudnary subregions, no explicit procedure for reconstructing the entanglement wedge was as of yet given. In this paper, mode sum approach to obtaining smearing functions is generalised to include bulk reconstruction in the entanglement wedge of boundary subregions. It is generally expectated that solutions to the wave equation on a complicated coordinate patch are needed, but this hard problem has been transferred to a less hard but tractable problem of matrix inversion.

  19. Non-Newtonian viscosity wedge in film formation of EHL

    Institute of Scientific and Technical Information of China (English)

    GUOF.; WONGP.L.

    2001-01-01

    This paper aims to evaluate the action of viscosity wedge in the oil film formation ofEHL at opposite sliding and zero entrainment. Using solvers developed for Newtonian and Eyringfluids, the film formation behavior originating from viscosity wedge is investigated. The numericalsimulation displays that lubricant film formation induced by viscosity wedge is different from that bythe well-known geometrical wedge with entrainment in classic EHL. The numerical analyses showthat at high opposite sliding speed the viscosity wedge acts as a leading role in film formation, thenon-Newtonian effects can have a pronounced influence on action of the viscosity wedge.

  20. A review of dynamics modelling of friction wedge suspensions

    Science.gov (United States)

    Wu, Qing; Cole, Colin; Spiryagin, Maksym; Sun, Yan Quan

    2014-11-01

    Three-piece bogies with friction wedge suspensions are the most widely used bogies in heavy haul trains. Fiction wedge suspensions play a key role in these wagon systems. This article reviews current techniques in dynamic modelling of friction wedge suspension with various motivations: to improve dynamic models of friction wedge suspensions so as to improve general wagon dynamics simulations; to seek better friction wedge suspension models for wagon stability assessments in complex train systems; to improve the modelling of other friction devices, such as friction draft gear. Relevant theories and friction wedge suspension models developed by using commercial simulation packages and in-house simulation packages are reviewed.

  1. Graphene Plasmons in Triangular Wedges and Grooves

    DEFF Research Database (Denmark)

    Gonçalves, P. A. D.; Dias, E. J. C.; Xiao, Sanshui

    2016-01-01

    and electric-field distributions. We have found that the dispersion of wedge/groove graphene plasmons follows the same functional dependence as their flat-graphene plasmon counterparts, but now scaled by a (purely) geometric factor in which all the information about the system’s geometry is contained. We...... and tunability of graphene plasmons guided along the apex of a graphene-covered dielectric wedge or groove. In particular, we present a quasi-analytic model to describe the plasmonic eigenmodes in such a system, including the complete determination of their spectrum and corresponding induced potential...

  2. Joint application of Geoelectrical Resistivity and Ground Penetrating Radar techniques for the study of hyper-saturated zones. Case study in Egypt

    Science.gov (United States)

    Mesbah, Hany S.; Morsy, Essam A.; Soliman, Mamdouh M.; Kabeel, Khamis

    2017-06-01

    This paper presents the results of the application of the Geoelectrical Resistivity Sounding (GRS) and Ground Penetrating Radar (GPR) for outlining and investigating of surface springing out (flow) of groundwater to the base of an service building site, and determining the reason(s) for the zone of maximum degree of saturation; in addition to provide stratigraphic information for this site. The studied economic building is constructed lower than the ground surface by about 7 m. A Vertical Electrical Sounding (VES) survey was performed at 12 points around the studied building in order to investigate the vertical and lateral extent of the subsurface sequence, three VES's were conducted at each side of the building at discrete distances. And a total of 9 GPR profiles with 100- and 200-MHz antennae were conducted, with the objective of evaluating the depth and the degree of saturation of the subsurface layers. The qualitative and quantitative interpretation of the acquired VES's showed easily the levels of saturations close to and around the studied building. From the interpretation of GPR profiles, it was possible to locate and determine the saturated layers. The radar signals are penetrated and enabled the identification of the subsurface reflectors. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology. Finally, the new constructed geoelectrical resistivity cross-sections (in contoured-form), are easily clarifying the direction of groundwater flow toward the studied building.

  3. Fast Identification of Near-Trench Earthquakes Along the Mexican Subduction Zone Based on Characteristics of Ground Motion in Mexico City

    Science.gov (United States)

    Perez-Campos, X.; Singh, S. K.; Arroyo, D.; Rodríguez, Q.; Iglesias, A.

    2015-12-01

    The disastrous 1985 Michoacan earthquake gave rise to a seismic alert system for Mexico City which became operational in 1991. Initially limited to earthquakes along the Guerrero coast, the system now has a much wider coverage. Also, the 2004 Sumatra earthquake exposed the need for a tsunami early warning along the Mexican subduction zone. A fast identification of near-trench earthquakes along this zone may be useful in issuing a reliable early tsunami alert. The confusion caused by low PGA for the magnitude of an earthquake, leading to "missed" seismic alert, would be averted if its near-trench origin can be quickly established. It may also help reveal the spatial extent and degree of seismic coupling on the near-trench portion of the plate interface. This would lead to a better understanding of tsunami potential and seismic hazard along the Mexican subduction zone. We explore three methods for quick detection of near-trench earthquakes, testing them on recordings of 65 earthquakes at station CU in Mexico City (4.8 ≤Mw≤8.0; 270≤R≤615 km). The first method is based on the ratio of total to high-frequency energy, ER (Shapiro et al., 1998). The second method is based on parameter Sa*(6) which is the pseudo-acceleration response spectrum with 5% damping, Sa, at 6 s normalized by the PGA. The third parameter is the PGA residual, RESN, at CU, with respect to a newly-derived ground motion prediction equation at CU for coastal shallow-dipping thrust earthquakes following a bayesian approach. Since the near-trench earthquakes are relatively deficient in high-frequency radiation, we expect ER and Sa*(6) to be relatively large and RESN to be negative for such events. Tests on CU recordings show that if ER ≥ 100 and/or Sa*(6) ≥ 0.70, then the earthquake is near trench; for these events RESN ≤ 0. Such an event has greater tsunami potential. Few misidentifications and missed events are most probably a consequence of poor location, although unusual depth and source

  4. Benchmarking numerical models of brittle thrust wedges

    NARCIS (Netherlands)

    Buiter, Susanne J H; Schreurs, Guido; Albertz, Markus; Gerya, Taras V.; Kaus, Boris; Landry, Walter; le Pourhiet, Laetitia; Mishin, Yury; Egholm, David L.; Cooke, Michele; Maillot, Bertrand; Thieulot, Cedric; Crook, Tony; May, Dave; Souloumiac, Pauline; Beaumont, Christopher

    2016-01-01

    We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the s

  5. PARADOX SOLUTION ON ELASTIC WEDGE DISSIMILAR MATERIALS

    Institute of Scientific and Technical Information of China (English)

    姚伟岸; 张兵茹

    2003-01-01

    According to the Hellinger-Reissner variational principle and introducing proper transformation of variables, the problem on elastic wedge dissimilar materials can be led to Hamiltonian system, so the solution of the problem can be got by employing the separation of variables method and symplectic eigenfunction expansion under symplectic space, which consists of original variables and their dual variables. The eigenvalue - 1 is a special one of all symplectic eigenvalue for Hamiltonian system in polar coordinate. In general, the eigenvalue - is a single eigenvalue, and the classical solution of an elastic wedge dissimilar materials subjected to a unit concentrated couple at the vertex is got directly by solving the eigenfunction vector for eigenvalue - 1 . But the eigenvalue - 1 becomes a double eigenvalue when the vertex angles and modulus of the materials satisfy certain definite relationships and the classical solution for the stress distribution becomes infinite at this moment, that is, the paradox should occur. Here the Jordan form eigenfunction vector for eigenvalue - 1 exists, and solution of the paradox on elastic wedge dissimilar materials subjected to a unit concentrated couple at the vertex is obtained directly by solving this special Jordan form eigenfunction. The result shows again that the solutions of the special paradox on elastic wedge in the classical theory of elasticity are just Jordan form solutions in symplectic space under Hamiltonian system.

  6. P-wave anisotropy, mantle wedge flow and olivine fabrics beneath Japan

    Science.gov (United States)

    Liu, Xin; Zhao, Dapeng

    2017-09-01

    We present a new 3-D anisotropic P-wave velocity (Vp) model for the crust and upper mantle of the Japan subduction zone obtained by inverting a large number of high-quality P-wave traveltime data of local earthquakes and teleseismic events. By assuming orthorhombic anisotropy with a vertical symmetry axis existing in the modeling space, isotropic Vp tomography and 3-D Vp azimuthal and radial anisotropies are determined simultaneously. According to a simple flow field and the obtained Vp anisotropic tomography, we estimate the distribution of olivine fabrics in the mantle wedge. Our results show that the forearc mantle wedge above the subducting Pacific slab beneath NE Japan exhibits an azimuthal anisotropy with trench-parallel fast velocity directions (FVDs) and Vhf > Vv > Vhs (here Vv is Vp in the vertical direction, Vhf and Vhs are P-wave velocities in the fast and slow directions in the horizontal plane), where B-type olivine fabric with vertical trench-parallel flow may dominate. Such an anisotropic feature is not obvious in the forearc mantle wedge above the Philippine Sea (PHS) slab under SW Japan, probably due to higher temperatures and more fluids there associated with the young and warm PHS slab subduction. Trench-normal FVDs and Vhf > Vv > Vhs are generally revealed in the mantle wedge beneath the arc and backarc in Japan, where E-type olivine fabric with FVD-parallel horizontal flow may dominate. Beneath western Honshu, however, the mantle wedge exhibits an anisotropy of Vv > Vhf > Vhs and so C-type olivine fabric may dominate, suggesting that the water content is the highest there, because both the PHS and Pacific slabs exist there and their dehydration reactions release abundant fluids to the overlying mantle wedge.

  7. Radiotherapy treatment planning with dynamic wedges--an algorithm for generating wedge factors and beam data.

    Science.gov (United States)

    Thomas, S J; Foster, K R

    1995-09-01

    If the jaws of a linear accelerator are moved under computer control during irradiation, dose distributions similar to those with wedge filters can be produced. Varian linear accelerators utilize this effect to give a 'dynamic wedge', using segmented treatment tables (STTs). An algorithm is described to generate the dose per monitor unit at any point in a beam, using the STT values. Dynamically wedged beams are modelled as the superposition of static asymmetric beams, using an algorithm based on beam data measured for symmetric beams. Predictions of wedge factors, depth doses and profiles generated using the algorithm are compared with measurements. Good agreement is found between predictions and measurements. The calculation time is typically 5 ms/dose point on a PC with a 486DX processor.

  8. A comparison of exact TM plane wave diffraction by coated wedges and impedance wedges

    DEFF Research Database (Denmark)

    Andersen, Lars S.; Breinbjerg, Olav; Moore, John T.

    1996-01-01

    without interference from direct fields or reflected fields. Results have been obtained in the case of illumination by a transverse magnetic (TM) uniform plane wave. The analysis of the coated wedge is based on an integral equation formulation combined with a hybrid technique, while the analysis......The purpose of this work is to numerically investigate the accuracy of the standard impedance boundary condition (SIBC) approximation for edge diffraction. To this end, we compare the scattering by coated wedges and SIBC wedges for which the diffracted field from a single edge can be observed...... of the SIBC wedge is based on Maliuzhinets' solution. Comparisons have been carried out for a series of configurations including lossy coatings as well as lossless coatings permitting unattenuated propagation of surface waves. The results show that the presence of an edge in a coated structure does...

  9. Empirical model for mean temperature for Indian zone and estimation of precipitable water vapor from ground based GPS measurements

    Directory of Open Access Journals (Sweden)

    C. Suresh Raju

    2007-10-01

    Full Text Available Estimation of precipitable water (PW in the atmosphere from ground-based Global Positioning System (GPS essentially involves modeling the zenith hydrostatic delay (ZHD in terms of surface Pressure (Ps and subtracting it from the corresponding values of zenith tropospheric delay (ZTD to estimate the zenith wet (non-hydrostatic delay (ZWD. This further involves establishing an appropriate model connecting PW and ZWD, which in its simplest case assumed to be similar to that of ZHD. But when the temperature variations are large, for the accurate estimate of PW the variation of the proportionality constant connecting PW and ZWD is to be accounted. For this a water vapor weighted mean temperature (Tm has been defined by many investigations, which has to be modeled on a regional basis. For estimating PW over the Indian region from GPS data, a region specific model for Tm in terms of surface temperature (Ts is developed using the radiosonde measurements from eight India Meteorological Department (IMD stations spread over the sub-continent within a latitude range of 8.5°–32.6° N. Following a similar procedure Tm-based models are also evolved for each of these stations and the features of these site-specific models are compared with those of the region-specific model. Applicability of the region-specific and site-specific Tm-based models in retrieving PW from GPS data recorded at the IGS sites Bangalore and Hyderabad, is tested by comparing the retrieved values of PW with those estimated from the altitude profile of water vapor measured using radiosonde. The values of ZWD estimated at 00:00 UTC and 12:00 UTC are used to test the validity of the models by estimating the PW using the models and comparing it with those obtained from radiosonde data. The region specific Tm-based model is found to be in par with if not better than a

  10. Metastable olivine wedge beneath northeast China and its applications

    Science.gov (United States)

    Jiang, G.; Zhao, D.; Zhang, G.

    2013-12-01

    When the Pacific slab subducted into the mantle transition zone, there might exist a metastable olivine wedge (MOW) inside the slab due to the phase transition. Lots of researchers have adopted such various methods to detect the characteristics of this MOW as the forward modeling of travel times, shear wave amplitude patterns, teleseismic P wave coda, receiver function imaging, thermodynamic simulation and so on. Almost all results could be more or less affected by the source, the receiver and/or the velocity model passed through by the seismic rays. In this study, we have used 21 deep earthquakes, greater than 400 km and locating beneath northeast China, to study the velocity within the MOW. For more precisions, we have done further modifications in two ways based on our previous studies. (1) Double-difference location method is used to relocate all events with an error of 1-2 km with the data recorded by stations both at northeast China and at Japan. All relocated events locate in a zone about 30 km away from the upper boundary of Pacific slab. (2) Double residual travel times, generated by an event-pair at a common station at only Japan, are used to constrain the velocity anomaly rather than the residuals themselves. As a result, we have found that an ultra-lower velocity zone (ULVZ), averagely -7% relative to the iasp91 model, exists within the subducted Pacific slab around the deep earthquakes, which might be represented as the metastable olivine wedge. Because of the lower-velocity corresponding to the lower-density, the MOW would provide upward buoyancy forces which might prevent the slab from free subduction into the mantle transition zone. This feed-back mechanism of MOW to the slab is called ';parachute-effect', which is characterized by other researchers. In addition, the existence of the ULVZ or the MOW in the slab may supply a possible mechanism for triggering deep earthquakes, called ';phase transformation faulting', which was already proposed few

  11. Structural, physiognomic and above-ground biomass variation in savanna-forest transition zones on three continents - how different are co-occurring savanna and forest formations?

    Science.gov (United States)

    Veenendaal, E. M.; Torello-Raventos, M.; Feldpausch, T. R.; Domingues, T. F.; Gerard, F.; Schrodt, F.; Saiz, G.; Quesada, C. A.; Djagbletey, G.; Ford, A.; Kemp, J.; Marimon, B. S.; Marimon-Junior, B. H.; Lenza, E.; Ratter, J. A.; Maracahipes, L.; Sasaki, D.; Sonke, B.; Zapfack, L.; Villarroel, D.; Schwarz, M.; Yoko Ishida, F.; Gilpin, M.; Nardoto, G. B.; Affum-Baffoe, K.; Arroyo, L.; Bloomfield, K.; Ceca, G.; Compaore, H.; Davies, K.; Diallo, A.; Fyllas, N. M.; Gignoux, J.; Hien, F.; Johnson, M.; Mougin, E.; Hiernaux, P.; Killeen, T.; Metcalfe, D.; Miranda, H. S.; Steininger, M.; Sykora, K.; Bird, M. I.; Grace, J.; Lewis, S.; Phillips, O. L.; Lloyd, J.

    2015-05-01

    Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna-forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna-forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three continents coexistence

  12. Structural, physiognomic and above-ground biomass variation in savanna–forest transition zones on three continents – how different are co-occurring savanna and forest formations?

    Directory of Open Access Journals (Sweden)

    E. M. Veenendaal

    2015-05-01

    Full Text Available Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna–forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna–forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three

  13. Seismic architecture and sedimentology of a major grounding zone system deposited by the Bjørnøyrenna Ice Stream during Late Weichselian deglaciation

    Science.gov (United States)

    Rüther, Denise Christina; Mattingsdal, Rune; Andreassen, Karin; Forwick, Matthias; Husum, Katrine

    2011-09-01

    A 280 km wide sediment wedge in outer Bjørnøyrenna (Bear Island Trough), south-western Barents Sea, has been investigated using 2D and 3D seismic data, sediment gravity cores, as well as regional swath and large scale bathymetry data. The bathymetry data indicate a division into an up to 35 m high frontal wedge with large depressions, and an upstream part characterized by mega scale glacial lineations (MSGL). From seismic sections increasing erosion is demonstrated for the upstream part, coinciding with the location of MSGL. Whether the latter are depositional features postdating an extensive erosional event or formed by erosion remains inconclusive. Based on the distinct morphology and internal structures, we infer that the system was deposited during a rapid readvance whereby the ice front pushed and bulldozed predominantly soft, diluted proglacial sediments. Analyses in the eastern part of the sediment system reveal the existence of imbricated thrust sheets in the frontal part of the wedge. This is suggested to imply upstream erosion of sedimentary rock and incorporation of thrusted blocks into the moraine, forming a composite ridge locally. We argue that observed large scale depressions are dead-ice features in the marine environment. It is envisioned that intense englacial thrusting may have developed into a decollement as the cold glacier snout got overrun by ice masses from the interior, thereby enabling the inclusion of slabs of ice in the push moraine mass. Radiocarbon dates indicate that the sediment wedge was deposited around 17,090 cal yrs BP (14,530 14C yrs BP) and that the ice front probably remained stable until 16,580 cal yrs BP (13,835 14C yrs BP).

  14. Low-Temperature Softening Due to Vacancy Orbital with Γ8 Quartet Ground State in Boron-Doped Floating Zone Silicon

    Science.gov (United States)

    Baba, Shotaro; Akatsu, Mitsuhiro; Mitsumoto, Keisuke; Komatsu, Satoru; Horie, Kunihiko; Nemoto, Yuichi; Yamada-Kaneta, Hiroshi; Goto, Terutaka

    2013-08-01

    We have carried out low-temperature ultrasonic measurements using shear-mode ultrasound to clarify the quantum state of a vacancy orbital in boron-doped silicon grown by the floating zone (FZ) method. The elastic constants (C11-C12)/2 and C44 of the transverse mode exhibit considerable softening below 2 and 5 K down to the base temperature of 30 mK, respectively. The elastic constant C44 measured by the three ultrasonic modes (kx,uy), (kz,ux), and (kx,uz) shows the different magnetic field dependences among the configurations under applied magnetic fields along the z-axis. The elastic softening and the magnetic field dependence of the elastic constants are accounted for by the quadrupole susceptibility based on the energy level scheme of the vacancy orbital with a Γ8 quartet ground state and Γ7 doublet excited state located at an energy of 1 K. The difference in C44 between the two ultrasonic modes (kz,ux) and (kx,uz) at fields along the z-axis indicates that the Γ8 quartet ground state is slightly split by local strain in the silicon sample. The quantum state of the vacancy orbital is expected to be sensitive to strain because of the extremely large quadrupole-strain coupling energy of gΓ≈ 105 K due to the extensively spreading orbital radius of r≈ 1 nm. The differences in variation of the low-temperature softening and magnetic field dependence among eight samples cut out from different locations of the present boron-doped FZ silicon ingot evidence the inhomogeneous distribution of the vacancy concentration.

  15. Downscaling Satellite Data for Predicting Catchment-scale Root Zone Soil Moisture with Ground-based Sensors and an Ensemble Kalman Filter

    Science.gov (United States)

    Lin, H.; Baldwin, D. C.; Smithwick, E. A. H.

    2015-12-01

    Predicting root zone (0-100 cm) soil moisture (RZSM) content at a catchment-scale is essential for drought and flood predictions, irrigation planning, weather forecasting, and many other applications. Satellites, such as the NASA Soil Moisture Active Passive (SMAP), can estimate near-surface (0-5 cm) soil moisture content globally at coarse spatial resolutions. We develop a hierarchical Ensemble Kalman Filter (EnKF) data assimilation modeling system to downscale satellite-based near-surface soil moisture and to estimate RZSM content across the Shale Hills Critical Zone Observatory at a 1-m resolution in combination with ground-based soil moisture sensor data. In this example, a simple infiltration model within the EnKF-model has been parameterized for 6 soil-terrain units to forecast daily RZSM content in the catchment from 2009 - 2012 based on AMSRE. LiDAR-derived terrain variables define intra-unit RZSM variability using a novel covariance localization technique. This method also allows the mapping of uncertainty with our RZSM estimates for each time-step. A catchment-wide satellite-to-surface downscaling parameter, which nudges the satellite measurement closer to in situ near-surface data, is also calculated for each time-step. We find significant differences in predicted root zone moisture storage for different terrain units across the experimental time-period. Root mean square error from a cross-validation analysis of RZSM predictions using an independent dataset of catchment-wide in situ Time-Domain Reflectometry (TDR) measurements ranges from 0.060-0.096 cm3 cm-3, and the RZSM predictions are significantly (p State Integrated Hydrologic Modeling (PIHM) system. Uncertainty estimates are significantly (p < 0.05) correlated to cross validation error during wet and dry conditions, but more so in dry summer seasons. Developing an EnKF-model system that downscales satellite data and predicts catchment-scale RZSM content is especially timely, given the anticipated

  16. Radiation pressure on a dielectric wedge

    CERN Document Server

    Mansuripur, Masud; Moloney, Jerome V

    2014-01-01

    The force of electromagnetic radiation on a dielectric medium may be derived by a direct application of the Lorentz law of classical electrodynamics. While the light's electric field acts upon the (induced) bound charges in the medium, its magnetic field exerts a force on the bound currents. We use the example of a wedge-shaped solid dielectric, immersed in a transparent liquid and illuminated at Brewster's angle, to demonstrate that the linear momentum of the electromagnetic field within dielectrics has neither the Minkowski nor the Abraham form; rather, the correct expression for momentum density has equal contributions from both. The time rate of change of the incident momentum thus expressed is equal to the force exerted on the wedge plus that experienced by the surrounding liquid.

  17. Graphene Plasmons in Triangular Wedges and Grooves

    CERN Document Server

    Gonçalves, P A D; Xiao, Sanshui; Vasilevskiy, M I; Mortensen, N Asger; Peres, N M R

    2016-01-01

    The ability to effectively guide electromagnetic radiation below the diffraction limit is of the utmost importance in the prospect of all-optical plasmonic circuitry. Here, we propose an alternative solution to conventional metal-based plasmonics by exploiting the deep subwavelength confinement and tunability of graphene plasmons guided along the apex of a graphene-covered dielectric wedge or groove. In particular, we present a quasi-analytic model to describe the plasmonic eigenmodes in such a system, including the complete determination of their spectrum and corresponding induced potential and electric field distributions. We have found that the dispersion of wedge/groove graphene plasmons follows the same functional dependence as their flat-graphene plasmons counterparts, but now scaled by a (purely) geometric factor in which all the information about the system's geometry is contained. We believe our results pave the way for the development of novel custom-tailored photonic devices for subwavelength waveg...

  18. Understanding Resilience Dimensions and Adaptive Strategies to the Impact of Recurrent Droughts in Borana Zone, Oromia Region, Ethiopia: A Grounded Theory Approach.

    Science.gov (United States)

    Birhanu, Zewdie; Ambelu, Argaw; Berhanu, Negalign; Tesfaye, Abraraw; Woldemichael, Kifle

    2017-01-26

    Recurrent shocks and stresses are increasingly deteriorating pastoralist communities' resilience capacities in many aspects. A context specific resilience framework is essential to strengthen pastoralist community's resilience capacity towards the impact of recurrent drought. Hence, the present study was aimed to develop a context specific and data driven resilience building framework towards impacts of recurrent droughts in the case of Borana pastoralists in Ethiopia. Qualitative grounded theory approach was employed to guide the study process. The data were collected through focus group discussions and in-depth interviews in two drought affected districts of Borana Zone during October 2013. The analysis was assisted by ATLAS. ti 7.1.4. The analysis provided a context specific resilience building conceptual tool, which consists of, closely interconnected, eight dimensions operating at multiple capacities and levels: environment (underlying vulnerability factor); livestock, infrastructures/social services, and wealth (immediate causes and effects); community network/social capital, as well as governance, peace and security (support and enabling factors oriented), psychosocial, and human capital (as eventual outcomes and impacts). The resilience capacities of these pastoralist communities have been eroded, leaving them without sufficient and effective adaptive strategies. The emergent resilience framework can serve as a useful guidance to design context-specific interventions that makes the people and the system resilient to the impacts of recurrent droughts.

  19. Understanding Resilience Dimensions and Adaptive Strategies to the Impact of Recurrent Droughts in Borana Zone, Oromia Region, Ethiopia: A Grounded Theory Approach

    Directory of Open Access Journals (Sweden)

    Zewdie Birhanu

    2017-01-01

    Full Text Available Recurrent shocks and stresses are increasingly deteriorating pastoralist communities’ resilience capacities in many aspects. A context specific resilience framework is essential to strengthen pastoralist community’s resilience capacity towards the impact of recurrent drought. Hence, the present study was aimed to develop a context specific and data driven resilience building framework towards impacts of recurrent droughts in the case of Borana pastoralists in Ethiopia. Qualitative grounded theory approach was employed to guide the study process. The data were collected through focus group discussions and in-depth interviews in two drought affected districts of Borana Zone during October 2013. The analysis was assisted by ATLAS. ti 7.1.4. The analysis provided a context specific resilience building conceptual tool, which consists of, closely interconnected, eight dimensions operating at multiple capacities and levels: environment (underlying vulnerability factor; livestock, infrastructures/social services, and wealth (immediate causes and effects; community network/social capital, as well as governance, peace and security (support and enabling factors oriented, psychosocial, and human capital (as eventual outcomes and impacts. The resilience capacities of these pastoralist communities have been eroded, leaving them without sufficient and effective adaptive strategies. The emergent resilience framework can serve as a useful guidance to design context-specific interventions that makes the people and the system resilient to the impacts of recurrent droughts.

  20. Understanding Resilience Dimensions and Adaptive Strategies to the Impact of Recurrent Droughts in Borana Zone, Oromia Region, Ethiopia: A Grounded Theory Approach

    Science.gov (United States)

    Birhanu, Zewdie; Ambelu, Argaw; Berhanu, Negalign; Tesfaye, Abraraw; Woldemichael, Kifle

    2017-01-01

    Recurrent shocks and stresses are increasingly deteriorating pastoralist communities’ resilience capacities in many aspects. A context specific resilience framework is essential to strengthen pastoralist community’s resilience capacity towards the impact of recurrent drought. Hence, the present study was aimed to develop a context specific and data driven resilience building framework towards impacts of recurrent droughts in the case of Borana pastoralists in Ethiopia. Qualitative grounded theory approach was employed to guide the study process. The data were collected through focus group discussions and in-depth interviews in two drought affected districts of Borana Zone during October 2013. The analysis was assisted by ATLAS. ti 7.1.4. The analysis provided a context specific resilience building conceptual tool, which consists of, closely interconnected, eight dimensions operating at multiple capacities and levels: environment (underlying vulnerability factor); livestock, infrastructures/social services, and wealth (immediate causes and effects); community network/social capital, as well as governance, peace and security (support and enabling factors oriented), psychosocial, and human capital (as eventual outcomes and impacts). The resilience capacities of these pastoralist communities have been eroded, leaving them without sufficient and effective adaptive strategies. The emergent resilience framework can serve as a useful guidance to design context-specific interventions that makes the people and the system resilient to the impacts of recurrent droughts. PMID:28134771

  1. Checking the virtual treatment modality Wedge from Siemens; Verificacion de la modalidad de tratamiento virtual WEDGE de SIEMENS

    Energy Technology Data Exchange (ETDEWEB)

    Suero Rodrigo, M. A.; Marques Fraguela, E.

    2011-07-01

    The treatment modality Virtual Wedge (VW) or implemented by Siemens virtual wedge in electron linear accelerators achieved dose distributions are similar but not identical, to those obtained with physical wedges. Among the advantages against the latter is the greater ease of use, wedge factor close to one, and lower peripheral dose. However, these benefits are to be effective requires a through quality control dependence because a larger number of parameters that control the generation of the beam, the dose monitor system and the movement of the jaws of the collimator. We performed a study of the wedge taking into account different configurations that can affect their behavior from the dosimetric point of view.

  2. 河西走廊末次冰期砂楔的发现及其古气候意义%The Discovery of Sand Wedges of the Last Glaciation in the Hexi Corridor and Its Paleoclimatic Significance

    Institute of Scientific and Technical Information of China (English)

    王乃昂; 王涛; 史正涛; 胡刚; 高顺尉

    2001-01-01

    Sand wedge is formed under cold climate, and is an important basis for reconstructing paleoenvironment. It has been reported constantly over the last 20 years in the Tibetan Plateau, North China and Northeast China. Fossil sand wedge groups at the end of the Late Pleistocene recently are found in Jiuquan, Anxi, Dunhuang and other areas in the Hexi Corridor now. The fossil sand wedges, found by the authors, were mainly formed in alluvial gravel stratum of bajada and piedmont alluvial plain. Based on the field incomplete statistics, the top-width of them is usually 12~30 cm, with a depth of 17~ 70 cm and a mean ratio of width to depth of 1: 1. 61. Their morphometrics appear bottom-cuspate wedge, deep and narrow. Most of wedge bottom is single cusp. Eolian sand is filled in all wedge body. It is found from the granulometric composition of two sample groups that fine sand ranging from 0.25 to 0. 125 mm is the maximum; followed by very fine sand ranging from 0. 125 to 0. 063 mm, and the physical clay, less than 0.002 mm, is less than 3%. A thin layer of grail overlies the top of the sand-wedge groups. According to the morphological characteristics of profile, sand wedges have nothing to do with tectonic movement, fluvial erosion and drying crack of ground surface, but have something to do with disturbance caused by seasonal process of permafrost. "C dating of dripping carbonate within the sand wedges from the Anxi County shows that they were formed at about (22 500-±190) a BP and (19 100±125) a BP, during the Last Ice Age. The study suggests that the Hexi Corridor was the southern periphery of the continuous permafrost zone with a climate rather cold and relatively moist at the Last Ice Age, because the region was situated in a transitional zone under the interaction of monsoon-westerly. According to the temperature suggested by Romanovskiy for the formation of sand wedge within gravel, it is estimated that the annual mean air temperature during the Last

  3. Measured Two-Dimensional Ice-Wedge Polygon Thermal Dynamics

    Science.gov (United States)

    Cable, William; Romanovsky, Vladimir; Busey, Robert

    2016-04-01

    Ice-wedge polygons are perhaps the most dominant permafrost related features in the arctic landscape. The microtopography of these features, that includes rims, troughs, and high and low polygon centers, alters the local hydrology, as water tends to collect in the low areas. During winter, wind redistribution of snow leads to an increased snowpack depth in the low areas, while the slightly higher areas often have very thin snow cover, leading to differences across the landscape in vegetation communities and soil moisture between higher and lower areas. These differences in local surface conditions lead to spatial variability of the ground thermal regime in the different microtopographic areas and between different types of ice-wedge polygons. To study these features in depth, we established temperature transects across four different types of ice-wedge polygons near Barrow, Alaska. The transects were composed of five vertical array thermistor probes (VATP) beginning in the center of each polygon and extending through the trough to the rim of the adjacent polygon. Each VATP had 16 thermistors from the surface to a depth of 1.5 m. In addition to these 80 subsurface temperature measurement points per polygon, soil moisture, thermal conductivity, heat flux, and snow depth were all measured in multiple locations for each polygon. Above ground, a full suite of micrometeorological instrumentation was present at each polygon. Data from these sites has been collected continuously for the last three years. We found snow cover, timing and depth, and active layer soil moisture to be major controlling factors in the observed thermal regimes. In troughs and in the centers of low-center polygons, the combined effect of typically saturated soils and increased snow accumulation resulted in the highest mean annual ground temperatures (MAGT). Additionally, these areas were the last part of the polygon to refreeze during the winter. However, increased active layer thickness was not

  4. Ground-penetrating radar images of a dye tracer test within the unsaturated zone at the Susquehanna-Shale Hills CZO

    Science.gov (United States)

    Pitman, Lacey M.

    Dye tracer and time-lapse ground-penetrating radar (GPR) were used to image preferential flow paths in the shallow, unsaturated zone on hillslopes in two adjacent watersheds within the Susquehanna-Shale Hills Critical Zone Observatory (CZO). At each site we injected about 50 L of water mixed with brilliant blue dye (4 g/L) into a trench cut perpendicular to the slope (˜1.0 m long by ˜0.20 m wide by ˜0.20 m deep) to create a line of infiltration. GPR (800 MHz antennae with constant offset) was used to monitor the movement of the dye tracer downslope on a 1.0 m x 2.0 m grid with a 0.05 m line spacing. The site was then excavated and the stained pathways photographed to document the dye movement. We saw a considerable difference in the pattern of shallow preferential flow between the two sites despite similar soil characteristics and slope position. Both sites showed dye penetrating down to saprolite (˜0.40 m); however, lateral flow migration between the two sites was different. At the Missed Grouse field site, the lateral migration was ˜0.55 m as an evenly dispersed plume, but at distance of 0.70 m a finger of dye was observed. At the Shale Hills field site, the total lateral flow was ˜0.40 m, dye was barely visible until the excavation reached ˜0.10 m, and there was more evidence of distinct fingering in the vertical direction. Based on laboratory and field experiments as well as processing of the radargrams, the following conclusions were drawn: 1) time-lapse GPR successfully delineated the extent of lateral flow, but the GPR resolution was insufficient to detect small fingers of dye; 2) there was not a distinct GPR reflection at the regolith-saprock boundary, but this interface could be estimated from the extent of signal attenuation; 3) the preliminary soil moisture conditions may explain differences in the extent of infiltration at the two sites; 4) rapid infiltration into the underlying saprock limited the extent of shallow lateral flow at both sites and

  5. Analysis of Metal Forming in Two-Roll Cross Wedge Rolling Process Using Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    WANG Min-ting; LI Xue-tong; DU Feng-shan

    2009-01-01

    A simulation model for two-roll cross wedge rolling (CWR) was presented by using three-dimensional rigid-plastic finite element method (FEM).The whole forming process of CWR,including knifing zone,guiding zone,stretching zone,and sizing zone,was simulated using the model in which dynamic adaptive remeshing technology for tetrahedral solid elements was used to fix element distortion.Based on the simulation results,the distributions of metal flow field,strain field,and damage field,and the geometry of the workpiece's end were analyzed.These results could provide theoretical guidance for realizing net shaping and reasonable design of tools.

  6. Hydrodynamics of slip wedge and optimization of surface slip property

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hydrodynamic load support generated by a slip wedge of a slider bearing was studied. The surface slip property was optimized so that a maximum hydrodynamic load support could be obtained. A multi-linearity method was given for the slip control equation of two-dimensional (2-D) wall slip. We investigated 2-D wall slip and the hydrodynamics of a finite length bearing with any values of the surface limiting shear stress. It was found that the hydrodynamic effect of the slip wedge is greater than the traditional geometrical convergent-wedge. Even though the geo- metrical gap is a parallel or divergent sliding gap, the slip wedge still gives rise to a very big hydrodynamic pressure. The optimized slip wedge can give rise to a hy- drodynamic load support as high as 2.5 times of what the geometrical conver- gent-wedge can produce. Wall slip usually gives a small surface friction.

  7. Hydrodynamics of slip wedge and optimization of surface slip property

    Institute of Scientific and Technical Information of China (English)

    MA GuoJun; WU ChengWei; ZHOU Ping

    2007-01-01

    The hydrodynamic load support generated by a slip wedge of a slider bearing was studied. The surface slip property was optimized so that a maximum hydrodynamic load support could be obtained. A multi-linearity method was given for the slip control equation of two-dimensional (2-D) wall slip. We investigated 2-D wall slip and the hydrodynamics of a finite length bearing with any values of the surface limiting shear stress. It was found that the hydrodynamic effect of the slip wedge is greater than the traditional geometrical convergent-wedge. Even though the geometrical gap is a parallel or divergent sliding gap, the slip wedge still gives rise to a very big hydrodynamic pressure. The optimized slip wedge can give rise to a hydrodynamic load support as high as 2.5 times of what the geometrical convergent-wedge can produce. Wall slip usually gives a small surface friction.

  8. Changes in basal dip and frictional properties controlling orogenic wedge propagation and frontal collapse: the External central Betics case

    Science.gov (United States)

    Jiménez-Bonilla, Alejandro; Torvela, Taija; Balanyá, Juan-Carlos; Díaz-Azpiroz, Manuel; Expósito, Inmaculada

    2016-04-01

    Orogenic wedges and their key component, thin-skinned fold-and-thrust belts (FTBs), have been extensively studied through both field examples and modelling. The overall dynamics of FTBs are, therefore, well understood. One of the less understood aspects is: what is the combined influence of across-strike changes in the detachment properties and the basement topography on the behaviour of an orogenic wedge, as the deformation progresses towards the foreland? In this study, we use field data combined with reflection seismic interpretation and well data from the External Zones of the Central Betics FTB, S Spain, to identify a basement "threshold" coinciding with a thinning out of a weak substrate (Triassic evaporites) in the wedge basal detachment. The basal changes influenced the tempo-spatial (4D) local wedge dynamics at ~Early Langhian times, leading to stagnation of FTB propagation, topographic build-up and subsequent collapse of the FTB front, which was enhanced by arc-parallel stretching. This development led to a formation of an important depocentre filled with a thick Langhian mélange unit and later sediments deposited in the NW-migrating foreland basin. This case study illustrates the importance of across-strike changes in wedge basal properties to the stability of the FTB front, especially in terms of the collapse/extensional structures.

  9. Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges.

    Science.gov (United States)

    Manthilake, Geeth; Bolfan-Casanova, Nathalie; Novella, Davide; Mookherjee, Mainak; Andrault, Denis

    2016-05-01

    Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

  10. Knee abduction angular impulses during prolonged running with wedged insoles.

    Science.gov (United States)

    Lewinson, Ryan T; Worobets, Jay T; Stefanyshyn, Darren J

    2013-07-01

    Wedged insoles may produce immediate effects on knee abduction angular impulses during running; however, it is currently not known whether these knee abduction angular impulse magnitudes are maintained throughout a run when fatigue sets in. If changes occur, this could affect the clinical utility of wedged insoles in treating conditions such as patellofemoral pain. Thus, the purpose of this study was to determine whether knee abduction angular impulses are altered during a prolonged run with wedged insoles. It was hypothesized that knee abduction angular impulses would be reduced following a prolonged run with wedged insoles. Nine healthy runners participated. Runners were randomly assigned to either a 6-mm medial wedge condition or a 6-mm lateral wedge condition and then ran continuously overground for 30 min. Knee abduction angular impulses were quantified at 0 and 30 min using a gait analysis procedure. After 2 days, participants returned to perform the same test but with the other wedge type. Two-way repeated-measures analysis of variance was used to evaluate main effects of wedge condition and time and interactions between wedge condition and time (α = 0.05). Paired t-tests were used for post hoc analysis (α = 0.01). No interaction effects (p = 0.958) were found, and knee abduction angular impulses were not significantly different over time (p = 0.384). Lateral wedge conditions produced lesser knee abduction angular impulses than medial conditions at 0 min (difference of 2.79 N m s, p = 0.006) and at 30 min (difference of 2.76 N m s, p < 0.001). It is concluded that significant knee abduction angular impulse changes within wedge conditions do not occur during a 30-min run. Additionally, knee abduction angular impulse differences between wedge conditions are maintained during a 30-min run.

  11. Plastic deformation of a wedge by a sliding punch

    Science.gov (United States)

    Nepershin, R. I.

    2016-11-01

    We present a self-similar solution of the problem of deformation of an ideally plastic wedge by a sliding punch with regard to contact friction; such a solution generalizes the well-known solutions of the problem of wedge penetration into a plastic half-space and of compression of an ideally plastic wedge by a plane punch. The problem is of interest for modeling the processes of plastic deformation of rough surfaces of metal pieces by a rigid tool.

  12. Optimal clinical implementation of the Siemens virtual wedge.

    Science.gov (United States)

    Walker, C P; Richmond, N D; Lambert, G D

    2003-01-01

    Installation of a modern high-energy Siemens Primus linear accelerator at the Northern Centre for Cancer Treatment (NCCT) provided the opportunity to investigate the optimal clinical implementation of the Siemens virtual wedge filter. Previously published work has concentrated on the production of virtual wedge angles at 15 degrees, 30 degrees, 45 degrees, and 60 degrees as replacements for the Siemens hard wedges of the same nominal angles. However, treatment plan optimization of the dose distribution can be achieved with the Primus, as its control software permits the selection of any virtual wedge angle from 15 degrees to 60 degrees in increments of 1 degrees. The same result can also be produced from a combination of open and 60 degrees wedged fields. Helax-TMS models both of these modes of virtual wedge delivery by the wedge angle and the wedge fraction methods respectively. This paper describes results of timing studies in the planning of optimized patient dose distributions by both methods and in the subsequent treatment delivery procedures. Employment of the wedge fraction method results in the delivery of small numbers of monitor units to the beam's central axis; therefore, wedge profile stability and delivered dose with low numbers of monitor units were also investigated. The wedge fraction was proven to be the most efficient method when the time taken for both planning and treatment delivery were taken into consideration, and is now used exclusively for virtual wedge treatment delivery in Newcastle. It has also been shown that there are no unfavorable dosimetric consequences from its practical implementation.

  13. Vibration frequencies of a constrained cantilever wedge

    Science.gov (United States)

    Craver, W. Lionel, Jr.; Lu, Yangshan

    1989-05-01

    This paper presents the solution for the natural frequencies of a beam tapered in one direction, or a wedge, with both a rotational and a translational constraint at a position along the length of the beam. The eigenfrequencies were determined using an incremental search and bisection method, accurate to the fourth decimal place. The taper ratio was varied from 1.4 to 5.0 and the dimensionless spring constants were varied from 0 to 1000. Graphs are provided to illustrate some results.

  14. Impingement of water droplets on wedges and double-wedge airfoils at supersonic speeds

    Science.gov (United States)

    Serafini, John S

    1954-01-01

    An analytical solution has been obtained for the equations of motion of water droplets impinging on a wedge in a two-dimensional supersonic flow field with a shock wave attached to the wedge. The closed-form solution yields analytical expressions for the equation of the droplet trajectory, the local rate of impingement and the impingement velocity at any point on the wedge surface, and the total rate of impingement. The analytical expressions are utilized to determine the impingement on the forward surfaces of diamond airfoils in supersonic flow fields with attached shock waves. The results presented include the following conditions: droplet diameters from 2 to 100 microns, pressure altitudes from sea level to 30,000 feet, free-stream static temperatures from 420 degrees r, free stream Mach numbers from 1.1 to 2.0, semiapex angles for the wedge from 1.14 degrees to 7.97 degrees, thickness-to-chord ratios for the diamond airfoil from 0.02 to 0.14, chord lengths from 1 to 20 feet, and angles of attack from zero to the inverse tangent of the airfoil thickness-to-chord ratio.

  15. Global Existence of a Shock for the Supersonic Flow Past a Curved Wedge

    Institute of Scientific and Technical Information of China (English)

    Hui Cheng YIN

    2006-01-01

    This note is devoted to the study of the global existence of a shock wave for the supersonic flow past a curved wedge. When the curved wedge is a small perturbation of a straight wedge and the angle of the wedge is less than some critical value, we show that a shock attached at the wedge will exist globally.

  16. Molecular depth profiling by wedged crater beveling.

    Science.gov (United States)

    Mao, Dan; Lu, Caiyan; Winograd, Nicholas; Wucher, Andreas

    2011-08-15

    Time-of-flight secondary ion mass spectrometry and atomic force microscopy are employed to characterize a wedge-shaped crater eroded by a 40-keV C(60)(+) cluster ion beam on an organic film of Irganox 1010 doped with Irganox 3114 delta layers. From an examination of the resulting surface, the information about depth resolution, topography, and erosion rate can be obtained as a function of crater depth for every depth in a single experiment. It is shown that when measurements are performed at liquid nitrogen temperature, a constant erosion rate and reduced bombardment induced surface roughness is observed. At room temperature, however, the erosion rate drops by ∼(1)/(3) during the removal of the 400 nm Irganox film and the roughness gradually increased to from 1 nm to ∼4 nm. From SIMS lateral images of the beveled crater and AFM topography results, depth resolution was further improved by employing glancing angles of incidence and lower primary ion beam energy. Sub-10 nm depth resolution was observed under the optimized conditions on a routine basis. In general, we show that the wedge-crater beveling is an important tool for elucidating the factors that are important for molecular depth profiling experiments.

  17. Ice-Creams and Wedge Graphs

    CERN Document Server

    Ackerman, Eyal; Pinchasi, Rom

    2011-01-01

    We show that for every compact convex set $S$ in the plane and every $0 < \\alpha < \\pi$, there exist a point $O$ and two supporting lines to $S$ passing through $O$ and touching $S$ at two \\emph{single points} $X$ and $Y$, respectively, such that $|OX|=|OY|$ and the angle between the two lines has measure $\\alpha$. As a consequence, we provide a simplified proof to the following result by Carmi, Katz, Lotker, and Ros\\'en \\cite{CKLR10}. Given a set of $\\frac{\\pi}{3}$-directional antennas (that is, antennas each of which can communicate along a wedge of angle $\\frac{\\pi}{3}$), one can always assign a direction to each antenna such that the resulting communication graph is connected, where two antennas can communicate if and only if each lies in the wedge assigned to the other. In fact we obtain a much stronger and optimal result (see Theorem \\ref{theorem:main}) saying in particular that one can chose the directions of the antennas so that the communication graph has diameter $\\le 4$.

  18. 49 CFR 215.113 - Defective plain bearing wedge.

    Science.gov (United States)

    2010-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RAILROAD FREIGHT CAR SAFETY STANDARDS Freight Car Components Suspension System § 215.113 Defective plain bearing wedge. A railroad may not place or continue in service a car, if a plain bearing wedge on that car is— (a) Missing; (b) Cracked; (c) Broken; or (d) Not...

  19. Comparison of wedge resection (Winograd procedure) and wedge resection plus complete nail plate avulsion in the treatment of ingrown toenails.

    Science.gov (United States)

    Huang, Jia-Zhang; Zhang, Yi-Jun; Ma, Xin; Wang, Xu; Zhang, Chao; Chen, Li

    2015-01-01

    The present retrospective study compared the efficacy of wedge resection (Winograd procedure) and wedge resection plus complete nail plate avulsion for the treatment of ingrown toenails (onychocryptosis). Two surgical methods were performed in 95 patients with a stage 2 or 3 ingrown toenail. Each patient was examined weekly until healing and then at 1, 6, and 12 months of follow-up. The outcomes measured were surgical duration, healing time, recurrence rate, the incidence of postoperative infection, and cosmetic appearance after surgery. Of the 95 patients (115 ingrown toenails) included in the present study, 39 (41.1%) underwent wedge resection (Winograd procedure) and 56 (59%), wedge resection plus complete nail plate avulsion. The mean surgical duration for wedge resection (Winograd procedure) and wedge resection plus complete nail plate avulsion was 14.9 ± 2.4 minutes and 15.1 ± 3.2 minutes, respectively (p = .73). The corresponding healing times were 2.8 ± 1.2 weeks and 2.7 ± 1.3 weeks (p = .70). Recurrence developed in 3 (3.2%) patients after wedge resection (Winograd procedure) and in 4 (4.2%) after wedge resection plus complete nail plate avulsion. In addition, postoperative infection occurred in 3 (3.2%) patients after wedge resection (Winograd procedure) and 2 (2.1%) after wedge resection plus complete nail plate avulsion. Both of the surgical procedures were practical and appropriate for the treatment of ingrown toenails, being simple and associated with low morbidity and a high success rate. However, cosmetically, wedge resection (Winograd procedure) would be the better choice because the nail plate remains intact.

  20. CHIRP seismic reflection study of falling-stage (forced regressive) sediment wedges on the New Jersey outer continental shelf

    Science.gov (United States)

    Santra, M.; Goff, J.; Ron, S.; Austin, J.

    2007-12-01

    High-resolution (1-12 kHz), deep-towed and hull-mounted CHIRP seismic data were collected on the New Jersey outer shelf in 2001, 2002 and 2006 as part of Office of Naval Research-funded projects. These data have imaged two well-developed, offlapping sedimentary wedges (named outer-shelf wedge and deep-shelf wedge) that are now postulated to have developed on the falling-stage limb of the last glacial cycle, during some time prior to the Last Glacial Maximum (20-22 kyrs BP). These wedges formed atop the high-amplitude, regional R horizon, a complex erosional unconformity that formed about 40,000 years ago. The outer shelf wedge is also characterized in part by an enigmatic, erose boundary separating layered horizons below from a mostly transparent section above. New Jersey shelf wedges appear analogous to forced-regressive units imaged on the Rhone shelf edge, as well as Eocene sections documented from seismic-scale outcrops on Spitsbergen Island. These examples can reach thicknesses up to 100 m on the shelf edge and uppermost slope, but usually thin rapidly downslope. Such wedges represent one of two documented mechanisms involving sand transport across a shelf margin into deeper water settings, the other being a canyonized shelf-edge. Our study will includes analysis of the CHIRP data and, if available, additional ground truth provided by short cores collected in summer 2007 at numerous intra-wedge stratigraphic horizons. Our goals are to understand the external and internal geometry of the wedges and sediment pathways across the paleo-shelf. These data should allow us to characterize margin segments that build during sea-level fall by slope-apron accretion rather than by the formation of channel-levee complexes. The literature is heavily weighted by the latter and their associated canyon systems, but information on shelf-edge attached slope aprons and how they contribute to deep-water sedimentation, and in particular the delivery of clean sands to slope settings

  1. Characterization of CNRS Fizeau wedge laser tuner

    Science.gov (United States)

    A fringe detection and measurement system was constructed for use with the CNRS Fizeau wedge laser tuner, consisting of three circuit boards. The first board is a standard Reticon RC-100 B motherboard which is used to provide the timing, video processing, and housekeeping functions required by the Reticon RL-512 G photodiode array used in the system. The sampled and held video signal from the motherboard is processed by a second, custom fabricated circuit board which contains a high speed fringe detection and locating circuit. This board includes a dc level discriminator type fringe detector, a counter circuit to determine fringe center, a pulsed laser triggering circuit, and a control circuit to operate the shutter for the He-Ne reference laser beam. The fringe center information is supplied to the third board, a commercial single board computer, which governs the data collection process and interprets the results.

  2. Coulomb theory applied to accretionary and nonaccretionary wedges: Possible causes for tectonic erosion and/or frontal accretion

    Science.gov (United States)

    Lallemand, Serge E.; Schnürle, Philippe; Malavieille, Jacques

    1994-06-01

    Based on observations from both modem convergent margins and sandbox modeling, we examine the possible conditions favoring frontal accretion and/or frontal and basal tectonic erosion. Mean characteristic parameters (μ, μ*b and λ) are used to discuss the mechanical stability of 28 transects across the frontal part of convergent margins where the Coulomb theory is applicable. Natural observations reveal that "typical accretionary wedges" are characterized by low tapers with smooth surface slope and subducting plate, low convergence rates and thick trench sediment, while "nonaccretionary wedges" display large tapers with irregular surface slopes and rough subducting plate, high convergence rates and almost no trench fill. Sandbox experiments were performed to illustrate the effects of seamounts/ridges in the subduction zone on the deformation of an accretionary wedge. These experiments show that a wedge of sand is first trapped and pushed in front of the seamount which acts as a moving bulldozer. This is followed by a tunnelling effect of the subducting seamount through the frontal wedge material, which results in considerable sand reworking. At an advanced subduction stage, the décollement jumps back from a high level in the wedge to its former basal position. We conclude that a high trench sedimentation rate relative to the convergence rate leads to frontal accretion. In contrast, several conditions may favor tectonic erosion of the upper plate. First, oceanic features, such as grabens, seamounts or ridges, may trap upper plate material during their subduction process. Second, destabilization of the upper plate material by internal fluid overpressuring causing hydrofracturing is probably another important mechanism.

  3. Control of structural inheritance on thrust initiation and material transfer in accretionary wedges

    Science.gov (United States)

    Leever, Karen; Geersen, Jacob; Ritter, Malte; Lieser, Kathrin; Behrmann, Jan

    2016-04-01

    Faults in the incoming sediment layer are commonly observed in subduction zone settings and well developed in the incoming plate off Sumatra. To investigate how they affect the structural development of the accretionary wedge, we conducted a series of 2D analogue tectonic experiments in which a 2 cm thick quartz sand layer on top of a thin detachment layer of glass beads was pulled against a rigid backstop by a basal conveyor belt in a 20cm wide box with glass walls. A gap at the base of the back wall avoids entrainment of the glass beads. At regular spacing of either 2.3, 5.5 or 7.8 cm (fractions of the thrust sheet length in the reference model), conjugate pairs of weakness zones dipping 60deg were created by cutting the sand layer with a thin (1 mm) metal blade. Both the undisturbed sand and the pre-cuts have an angle of internal friction of ~29o, but their cohesion is different by 50 Pa (110 Pa for the undisturbed material, 60 Pa along the pre-cuts). Friction of the glass beads is ~24deg. The experiments are monitored with high resolution digital cameras; displacement fields derived from digital image correlation are used to constrain fault activity. In all experiments, a critically tapered wedge developed with a surface slope of 7.5deg. In the reference model (no weakness zones in the input section), the position of new thrust faults is controlled by the frontal slope break. The average length of the thrust sheets is 11 cm and the individual thrusts accommodate on average 8 cm displacement each. The presence of weakness zones causes thrust initiation at a position different from the reference case, and affects their dip. For a fault spacing of 7.8 cm (or 75% of the reference thrust sheet length), every single incoming weakness zone causes the formation of a new thrust, thus resulting in thrust sheets shorter than the equilibrium case. In addition, less displacement is accommodated on each thrust. As a consequence, the frontal taper is smaller than expected

  4. A 5° medial wedge reduces frontal but not saggital plane motion during jump landing in highly trained women athletes

    Directory of Open Access Journals (Sweden)

    Michael F Joseph

    2010-03-01

    Full Text Available Michael F Joseph1, Craig R Denegar1, Elaine Horn1, Bradley MacDougall1, Michael Rahl1, Jessica Sheehan1, Thomas Trojian2, Jeffery M Anderson1, James E Clark1, William J Kraemer11Department of Kinesiology, 2Department of Sports Medicine, University of Connecticut, Storrs, CT, USAAbstract: Lower extremity mechanics during landing have been linked to traumatic and nontraumatic knee injuries, particularly in women’s athletics. The effects of efforts to mitigate these risks have not been fully elucidated. We previously reported that a 5° medial wedge reduced ankle eversion and knee valgus. In the present report we further investigated the effect of a 5° medial wedge inserted in the shoes of female athletes on frontal plane hip motion, as well as ankle, knee, hip, and trunk saggital plane motion during a jump landing task. Kinematic data were obtained from 10 intercollegiate female athletes during jump landings from a 31 cm platform with and without a 5° medial wedge. Hip adduction was reduced 1.98° (95% CI 0.97–2.99° by the medial wedge but saggital plane motions were unaffected. A 5° medial wedge reduces frontal plane motion and takes the knee away from a position associated with anterior cruciate ligament injury and patellofemoral pain syndrome. Although frontal plane motion was not captured it is unlikely to have increased in a bilateral landing task. Thus, it is likely that greater muscle forces were generated in these highly trained athletes to dissipate ground reaction forces when a medial wedge was in place. Additional investigation in younger and lesser trained athletes is warranted to assess the impact of orthotic devices on knee joint mechanics.Keywords: jump landing, foot orthotic, lower extremity kinematics, knee biomechanics, knee injury

  5. The Tax Wedge in Slovenia: International Comparison and Policy Recommendations

    Directory of Open Access Journals (Sweden)

    Primož Dolenc

    2005-09-01

    Full Text Available When taxes on labor are introduced, a “tax wedge” appears between the labor costs paid by the employer (gross wage and the net wage received by an employee. At a certain level of wage, a higher tax wedge increases unemployment and decreases employment, all other things being equal. The paper tackles three main questions: the characteristics of the tax wedge, unemployment and employment rates in OECD countries in the recent past, tax wedge policy in the EU15 and the new EU members and the tax system and its effects on the unemployment and employment rates in Slovenia. We found that the OECD countries can be classified into two groups of countries if the tax wedge, the unemployment rate and the employment rate are taken into consideration. The first group is the high tax wedge, high unemployment rate and low employment rate group of countries, whereas the other group has the opposite characteristics. European member states (old and new have on average a higher tax burden on labor than the OECD average, consequently suffering from higher unemployment rates. Slovenia has an unreasonably high tax wedge; in the EU only Belgium and Germany have a higher tax burden. According to previous and our empirical findings we suggest that Slovenia could benefit from a reduction in the tax wedge.

  6. Group sequential designs for stepped-wedge cluster randomised trials.

    Science.gov (United States)

    Grayling, Michael J; Wason, James Ms; Mander, Adrian P

    2017-06-01

    The stepped-wedge cluster randomised trial design has received substantial attention in recent years. Although various extensions to the original design have been proposed, no guidance is available on the design of stepped-wedge cluster randomised trials with interim analyses. In an individually randomised trial setting, group sequential methods can provide notable efficiency gains and ethical benefits. We address this by discussing how established group sequential methodology can be adapted for stepped-wedge designs. Utilising the error spending approach to group sequential trial design, we detail the assumptions required for the determination of stepped-wedge cluster randomised trials with interim analyses. We consider early stopping for efficacy, futility, or efficacy and futility. We describe first how this can be done for any specified linear mixed model for data analysis. We then focus on one particular commonly utilised model and, using a recently completed stepped-wedge cluster randomised trial, compare the performance of several designs with interim analyses to the classical stepped-wedge design. Finally, the performance of a quantile substitution procedure for dealing with the case of unknown variance is explored. We demonstrate that the incorporation of early stopping in stepped-wedge cluster randomised trial designs could reduce the expected sample size under the null and alternative hypotheses by up to 31% and 22%, respectively, with no cost to the trial's type-I and type-II error rates. The use of restricted error maximum likelihood estimation was found to be more important than quantile substitution for controlling the type-I error rate. The addition of interim analyses into stepped-wedge cluster randomised trials could help guard against time-consuming trials conducted on poor performing treatments and also help expedite the implementation of efficacious treatments. In future, trialists should consider incorporating early stopping of some kind into

  7. Stable and Critical Noncohesive Coulomb Wedges: Exact Elastic Solutions

    Science.gov (United States)

    Wang, K.; Hu, Y.

    2004-12-01

    The theory of critically tapered Coulomb wedge has been successfully applied to model active fold-and-thrust belts or submarine accretionary prisms. Brittle mountain building is episodic in nature, controlled by changes in basal friction, erosion and sedimentation, and hydrogeology. Sediment accretion may be modulated by great subduction earthquakes. Between deformation episodes and/or during transition between compressional and extensional tectonics, the Coulomb wedges are stable (i.e., supercritical), to which the critical taper theory does not apply. In this work, we provide an exact elastic solution for stable wedges based on Airy stress functions. The stress equilibrium equation and definition of basal friction and basal and internal pore fluid pressure ratios are exactly the same as those used for Dahlen's [1984] exact solution for critical noncohesive Coulomb wedges, but internal friction μ becomes irrelevant. Given elastic - perfectly Coulomb-plastic rheology, for stresses in a wedge on the verge of Coulomb failure there must co-exist a critical taper solution involving μ and a unique equivalent elastic solution not involving μ . Our elastic solution precisely reduces to Dahlen's critical taper solution for critical conditions. For stable conditions, normal stress perpendicular to the surface slope σ z and shear stress τ xz are identical with those in a critical taper, but the slope-parallel normal stress is different. The elastic solution is also generally applicable to purely elastic wedges and useful for modeling geodetic observations. A stable noncohesive Coulomb wedge differs from a general elastic wedge in that its upper and lower surfaces stay at zero curvature during loading. Dahlen, F.A. (1984), Noncohesive critical Coulomb wedges: An exact solution, JGR, 89, 10,125-10,133.

  8. Employment and productivity: The role of the tax wedge

    Directory of Open Access Journals (Sweden)

    Andrea FESTA

    2015-11-01

    Full Text Available After the economic crisis, many countries aim at reducing unemployment and foster productivity. To address these issues one of the most common policy indications recommends lowering the tax wedge on labour in order to increase employment and growth. As a consequence, a review of the empirical studies focused on the relation between tax wedge, employment and productivity is an useful and demanding exercise, especially in those European countries where the topic is on the front page of the domestic policy debate because the productivity growth is low and the tax wedge on labour is high.

  9. Olistostromes are the Source of Melange in Diapirs in the Cascadia-Olympics Accretionary Wedge , NW USA

    Science.gov (United States)

    Cowan, D. S.; Brandon, M. T.

    2011-12-01

    Diapirs consisting of block-in-matrix mélange are common in the ocean-ward part of the active Cascadia-Olympics wedge. Some of these bodies and similar Neogene mélanges ["Hoh mélange"] have been interpreted as having originated in shear zones related to accretion as oceanic crust of the Juan de Fuca plate was thrust beneath the wedge. However, this interpretation is untenable. The Hoh mélange contains fragments and blocks, ranging from centimeters to kilometers in size, of basalt. The chemistry of the basalt, and the microfossils in associated mudstone, prove that the basalt is Eocene: these basalts were derived from the Crescent Formation, not the much younger oceanic crust of the Juan de Fuca plate. The Crescent basalts originally formed the lid beneath which the Cascadia-Olympics wedge of sediments was underplated. Much of the lid has been eroded, but in Miocene time it extended to the coast and contributed fragments and blocks to muddy debris flows, which were deposited as olistostromes on the subducting Juan de Fuca plate. Younger sediments buried the olistostromes, which became overpressured and mobilized as mobile masses that have intruded as diapirs and anticlinal ridges. Analogous diapiric bodies, in the broad sense, are present in other active accretionary wedges, such as the in the Lesser Antilles.

  10. Decentralized Ground Staff Scheduling

    DEFF Research Database (Denmark)

    Sørensen, M. D.; Clausen, Jens

    2002-01-01

    Typically, ground staff scheduling is centrally planned for each terminal in an airport. The advantage of this is that the staff is efficiently utilized, but a disadvantage is that staff spends considerable time walking between stands. In this paper a decentralized approach for ground staff...... scheduling is investigated. The airport terminal is divided into zones, where each zone consists of a set of stands geographically next to each other. Staff is assigned to work in only one zone and the staff scheduling is planned decentralized for each zone. The advantage of this approach is that the staff...... work in a smaller area of the terminal and thus spends less time walking between stands. When planning decentralized the allocation of stands to flights influences the staff scheduling since the workload in a zone depends on which flights are allocated to stands in the zone. Hence solving the problem...

  11. Flow braking and the substorm current wedge

    Science.gov (United States)

    Birn, J.; Hesse, M.; Haerendel, G.; Baumjohann, W.; Shiokawa, K.

    1999-09-01

    Recent models of magnetotail activity have associated the braking of earthward flow with dipolarization and the reduction and diversion of cross-tail current, that is, the signatures of the substorm current wedge. Estimates of the magnitude of the diverted current by Haerendel [1992] and Shiokawa et al. [1997, 1998] tend to be lower than results from computer simulations of magnetotail reconnection and tail collapse [Birn and Hesse, 1996], despite similar underlying models. An analysis of the differences between these estimates on the basis of the simulations gives a more refined picture of the diversion of perpendicular into parallel currents. The inertial currents considered by Haerendel [1992] and Shiokawa et al. [1997] contribute to the initial current reduction and diversion, but the dominant and more permanent contribution stems from the pressure gradient terms, which change in connection with the field collapse and distortion. The major effect results from pressure gradients in the z direction, rather than from the azimuthal gradients [Shiokawa et al., 1998], combined with changes in By and Bx. The reduction of the current density near the equatorial plane is associated with a reduction of the curvature drift which overcompensates changes of the magnetization current and of the gradient B drift current. In contrast to the inertial current effects, the pressure gradient effects persist even after the burst of earthward flow ends.

  12. Modes of continental extension in a lithospheric wedge

    Science.gov (United States)

    Wu, G.; Lavier, L. L.; Choi, E.

    2014-12-01

    We studied extension of a lithospheric wedge as an approximation to an orogenic belt or a continental margin. We ran a series of numerical models to quantify the effects of the strength of the lower crust and a mid-crustal shear zone (MCSZ) on the extension processes. When the MCSZ is present, we found that the regional lower crustal flow plays a critical role in controlling the modes of extension. The compensation is long-wavelength when the lower crust flows from the highest to the lowest elevation in order to compensate upper crustal thinning. In response to this motion, the mantle flows towards the highest elevation in order to balance for the lower crust leaving the area under the highest topography. For weak (wet quartz regime with partial melting) or intermediate (wet quartz regime), or strong (dry quartz regime) lower crust, we recognized three predominantly decoupled modes of extension characterized by 1) significant lower crustal exhumation exemplified as a large massif, 2) formation of core complexes and detachment faults, and 3) distributive domino faulting, respectively. Without the MCSZ, however, the lower crustal flow is essentially subdued with predominantly coupled extension. For weak or intermediate, or strong lower crust, we recognized three coupled modes characterized by 1) localized generally symmetric crustal exhumation, 2) distributed grabens and narrow rifts, and 3) wide continental margins, respectively. The MCSZ controls the degree of decoupling of the lower crustal flow such that a frictionally stronger MCSZ does not change the behaviors of the models but results in a more distributed extension. Due to the long-wavelength compensation, subhorizontal Moho is achieved where intensive extension occurred for all the decoupled models with a MCSZ. Natural counterparts for each mode may be easily identified, for instance, in the Basin and Range or the Aegean.

  13. Casimir Effect for a Semitransparent Wedge and an Annular Piston

    CERN Document Server

    Milton, Kimball A; Kirsten, Klaus

    2009-01-01

    We consider the Casimir energy due to a massless scalar field in a geometry of an infinite wedge closed by a Dirichlet circular cylinder, where the wedge is formed by $\\delta$-function potentials, so-called semitransparent boundaries. A finite expression for the Casimir energy corresponding to the arc and the presence of both semitransparent potentials is obtained, from which the torque on the sidewalls can be derived. The most interesting part of the calculation is the nontrivial nature of the angular mode functions. Numerical results are obtained which are closely analogous to those recently found for a magnetodielectric wedge, with the same speed of light on both sides of the wedge boundaries. Alternative methods are developed for annular regions with radial semitransparent potentials, based on reduced Green's functions for the angular dependence, which allows calculations using the multiple-scattering formalism. Numerical results corresponding to the torque on the radial plates are likewise computed, whic...

  14. Electrodynamic Casimir effect in a medium-filled wedge.

    Science.gov (United States)

    Brevik, Iver; Ellingsen, Simen A; Milton, Kimball A

    2009-04-01

    We re-examine the electrodynamic Casimir effect in a wedge defined by two perfect conductors making dihedral angle alpha=pi/p. This system is analogous to the system defined by a cosmic string. We consider the wedge region as filled with an azimuthally symmetric material, with permittivity and permeability epsilon1, micro1 for distance from the axis ra. The results are closely related to those for a circular-cylindrical geometry, but with noninteger azimuthal quantum number mp. Apart from a zero-mode divergence, which may be removed by choosing periodic boundary conditions on the wedge, and may be made finite if dispersion is included, we obtain finite results for the free energy corresponding to changes in a for the case when the speed of light is the same inside and outside the radius a , and for weak coupling, |epsilon1-epsilon2|cosmic string, situated along the cusp line of the pre-existing wedge.

  15. ELASTIC INTERACTION BETWEEN WEDGE DISCLINATION DIPOLE AND INTERNAL CRACK

    Institute of Scientific and Technical Information of China (English)

    FANG Qi-hong; LIU You-wen

    2006-01-01

    The system of a wedge disclination dipole interacting with an internal crack was investigated. By using the complex variable method, the closed form solutions of complex potentials to this problem were presented. The analytic formulae of the physics variables, such as stress intensity factors at the tips of the crack produced by the wedge disclination dipole and the image force acting on disclination dipole center were obtained.The influence of the orientation, the dipole arm and the location of the disclination dipole on the stress intensity factors was discussed in detail. Furthermore, the equilibrium position of the wedge disclination dipole was also examined. It is shown that the shielding or antishielding effect of the wedge disclination to the stress intensity factors is significant when the disclination dipole moves to the crack tips.

  16. Reactive Atom Plasma Processing of Slumped Glass Wedges Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Reactive Atom Plasma (RAPTM) process will be evaluated as a rapid and practical method for fabricating precision wedges in glass sheets. The glass sheets are to...

  17. Structure and Kinematics of the Indo-Burmese Wedge

    Science.gov (United States)

    Maurin, T.; Rangin, C.

    2007-12-01

    The Burma subduction trench and the associated Indo Burmese wedge mark the present eastern boundary of the Indian plate in the northern Bengal area. The initiation, duration and history of the Bengal crust subduction beneath Burma is still debated. The aim of this paper is to provide a structural and kinematic analysis of the Indo- Burmese wedge in order to better constraints the Bengal crust subduction history beneath Burma. On the basis of field observations, seismic reflection data interpretation and well logs data we present a structural analysis of the Outer Indo-Burmese Wedge. We also constrain the onset of this Outer Wedge to be younger than 2Ma, implying a recent and fast westward growth (~10cm/yr) since Late Pliocene in close relationship with the onset of the Shillong plateau. Restoration process of a synthetic cross section through the Outer Wedge allowed us to estimate the amount of EW shortening accommodated in the Outer Wedge to be 5.1mm/yr since 2Ma. These results combined with previous available GPS data from central Myanmar suggest strain partitioning at wedge scale. The core of the wedge is affected by shear deformation and acts as a buttress for a frontal wedge that accommodates a more compressive strain component. Finally we propose that the main characteristic of the Indo-Burmese wedge growth mechanism is the progressive incorporation of the most internal part of the wedge, formerly affected by transpressive thin-skinned tectonics, to the buttress where they are subsequently affected by shear deformation. The crustal structure boarding the newly formed buttress seems to be guided by the subducting crust fabrics. We are in favour of a very recent (Late Miocene) onset of the present Indian crust subduction beneath Burma coeval with the global plate kinematics reorganisation related to the Indian/Australian plate spliting. This subduction postdates the Indo Burmese range onset that must have started in early Miocene. This range first began to

  18. Great Earthquakes and Orogenic Wedge Front Processes in the Bolivian Backarc

    Science.gov (United States)

    Brooks, B. A.; Arrowsmith, R.; Echalar, A.; Yagupsky, D.; Ericksen, T. L.; Weiss, J. R.; Ahlgren, K.; Bevis, M. G.; Whipple, K. X.

    2011-12-01

    The potential for earthquakes greater than Mw 8 rupturing the decollement below Bolivia's Southern Subandes orogenic wedge has been recently recognized although great events are not documented in historical seismicity catalogs and paleoseismologic studies in this part of Bolivia are non-existent. Here, we present the first evidence for a recent surface-rupturing event of at least 7m at the range-front Mandeyapecua fault near the town of Carandaiti. SRTM topography and published industry sub-surface data demonstrate that the ~500km long fault has at least three main segments, each greater than 100 km, with total relief of 10s of meters. We acquired kinematic GPS and terrestrial laser scanner surveys at 26 sites along the 2 northern segments of the fault. Everywhere the profiles of the frontal scarp are very similar to one another: relief is ~8-12m and scarp face inclination is ~7 degrees. Moreover, the slope faces are unbroken and have constant dip, consistent with a single event rupturing each site. We estimate paleo- Mw using thrust earthquake scaling relations and an across-strike rupture length of 85-100km (the locked zone from the geodetic studies). A rupture aspect ratio of ~1:1 sets the lower limit at ~ Mw 8.0 although, if a single event is responsible, then minimum magnitude is more likely Mw ~ 8.2-8.4. Regional geomorphic studies constrain the age of the faulted lithofacies from 1.6 to 4.4ka and minimum short-term slip rates from 4.3 to 1.8 mm/yr. For comparison, published dates and seismic reflection data yield a Quaternary slip rate of 2.4mm/yr. Each of these estimates is significantly less than the geodetically-determined, currently accumulating slip rate of ~10mm/yr. The implication, then, is that some of the other structures within the wedge must be active, although, as yet, we have found no field evidence for this. We use minimum work orogenic models to investigate the physical controls on fault activity in the wedge and show that, whereas for high

  19. Scattering of wedges and cones with impedance boundary conditions

    CERN Document Server

    Lyalinov, Mikhail

    2012-01-01

    This book is a systematic and detailed exposition of different analytical techniques used in studying two of the canonical problems, the wave scattering by wedges or cones with impedance boundary conditions. It is the first reference on novel, highly efficient analytical-numerical approaches for wave diffraction by impedance wedges or cones. The applicability of the reported solution procedures and formulae to existing software packages designed for real-world high-frequency problems encountered in antenna, wave propagation, and radar cross section.

  20. Optical refractometry based on Fresnel diffraction from a phase wedge.

    Science.gov (United States)

    Tavassoly, M Taghi; Saber, Ahad

    2010-11-01

    A method that utilizes the Fresnel diffraction of light from the phase step formed by a transparent wedge is introduced for measuring the refractive indices of transparent solids, liquids, and solutions. It is shown that, as a transparent wedge of small apex angle is illuminated perpendicular to its surface by a monochromatic parallel beam of light, the Fresnel fringes, caused by abrupt change in refractive index at the wedge lateral boundary, are formed on a screen held perpendicular to the beam propagation direction. The visibility of the fringes varies periodically between zero and 1 in the direction normal to the wedge apex. For a known or measured apex angle, the wedge refractive index is obtained by measuring the period length by a CCD. To measure the refractive index of a transparent liquid or solution, the wedge is installed in a transparent rectangle cell containing the sample. Then, the cell is illuminated perpendicularly and the visibility period is measured. By using modest optics, one can measure the refractive index at a relative uncertainty level of 10(-5). There is no limitation on the refractive index range. The method can be applied easily with no mechanical manipulation. The measuring apparatus can be very compact with low mechanical and optical noises.

  1. Conceptual design of heavy ion beam compression using a wedge

    Directory of Open Access Journals (Sweden)

    Jonathan C. Wong

    2015-10-01

    Full Text Available Heavy ion beams are a useful tool for conducting high energy density physics (HEDP experiments. Target heating can be enhanced by beam compression, because a shorter pulse diminishes hydrodynamic expansion during irradiation. A conceptual design is introduced to compress ∼100  MeV/u to ∼GeV/u heavy ion beams using a wedge. By deflecting the beam with a time-varying field and placing a tailor-made wedge amid its path downstream, each transverse slice passes through matter of different thickness. The resulting energy loss creates a head-to-tail velocity gradient, and the wedge shape can be designed by using stopping power models to give maximum compression at the target. The compression ratio at the target was found to vary linearly with (head-to-tail centroid offset/spot radius at the wedge. The latter should be approximately 10 to attain tenfold compression. The decline in beam quality due to projectile ionization, energy straggling, fragmentation, and scattering is shown to be acceptable for well-chosen wedge materials. A test experiment is proposed to verify the compression scheme and to study the beam-wedge interaction and its associated beam dynamics, which will facilitate further efforts towards a HEDP facility.

  2. Benchmarking analogue models of brittle thrust wedges

    Science.gov (United States)

    Schreurs, Guido; Buiter, Susanne J. H.; Boutelier, Jennifer; Burberry, Caroline; Callot, Jean-Paul; Cavozzi, Cristian; Cerca, Mariano; Chen, Jian-Hong; Cristallini, Ernesto; Cruden, Alexander R.; Cruz, Leonardo; Daniel, Jean-Marc; Da Poian, Gabriela; Garcia, Victor H.; Gomes, Caroline J. S.; Grall, Céline; Guillot, Yannick; Guzmán, Cecilia; Hidayah, Triyani Nur; Hilley, George; Klinkmüller, Matthias; Koyi, Hemin A.; Lu, Chia-Yu; Maillot, Bertrand; Meriaux, Catherine; Nilfouroushan, Faramarz; Pan, Chang-Chih; Pillot, Daniel; Portillo, Rodrigo; Rosenau, Matthias; Schellart, Wouter P.; Schlische, Roy W.; Take, Andy; Vendeville, Bruno; Vergnaud, Marine; Vettori, Matteo; Wang, Shih-Hsien; Withjack, Martha O.; Yagupsky, Daniel; Yamada, Yasuhiro

    2016-11-01

    We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing

  3. Electric currents of a substorm current wedge on 24 February 2010

    Science.gov (United States)

    Connors, Martin; McPherron, Robert L.; Anderson, Brian J.; Korth, Haje; Russell, Christopher T.; Chu, Xiangning

    2014-07-01

    The three-dimensional "substorm current wedge" (SCW) was postulated by McPherron et al. (1973) to explain substorm magnetic perturbations. The origin and coherence as a physical system of this important paradigm of modern space physics remained unclear, however, with progress hindered by gross undersampling, and uniqueness problems in data inversion. Complementing AMPERE (Active Magnetosphere and Planetary Electrodynamics Response Experiment) space-derived radial electric currents with ground magnetic data allowing us to determine currents from the ionosphere up, we overcome problems of uniqueness identified by Fukushima (1969, 1994). For a substorm on 24 February 2010, we quantify SCW development consistently from ground and space data. Its westward electrojet carries 0.5 MA in the more poleward part of the auroral oval, in Region 1 (R1) sense spanning midnight. The evening sector electrojet also feeds into its upward current. We thus validate the SCW concept and obtain parameters needed for quantitative study of substorms.

  4. Solutions for Groundwater Level in Effected Zone of Soft Ground Under Vacuum Preloading%真空预压影响区地下水位变化的计算

    Institute of Scientific and Technical Information of China (English)

    张仪萍; 李剑; 严露

    2011-01-01

    The analytical solution for ground water level changes in affected zone of soft ground with vacuum preloading was investigated by using one-dimensional unsteady seepage flow model. Using average groundwater zero pressure line in reinforced zone as the boundary condintion, solution of one-dimensional unsteady seepage flow model was conducted when reducation of water pressure in drainage boundary was changing over time. An example of the calculation based on the analyticalsolution was given to analyze the influence of permeability coefficient in affected zone and drainage rate in reinforcement area on groundwater level in affected zone. The results show that it is necessary to use unsteady seepage flow model to analysis soft clay that permeability is low and the permeability of soil in affected zone was the main factor to influene groundwater level outside reinforcement area. Drainage flow rate in reinforcement area only influence the time from unsteady seepage flow to steady flow but had less impact on flow range.%基于渗流理论,采用一维非稳定渗流模型,阐述了边界为变水头条件下的真空预压影响区地下水位变化的解析方法.利用加固区平均地下水零压线作为边界条件,推导了排水边界上降深随时间变化的一维非稳定渗流,得出影响区土体中地下水位的变化规律.通过算例,分析了影响区渗透系数以及预压区排水速率等因素对影响区地下水位的影响.结果表明,对于渗透性较低的软黏土而言,采用非稳定渗流分析是必要的,影响区渗透系数是区外地下水位变化的主要因素.预压区排水速率只影响区外渗流趋于稳定的时间,对渗流范围的影响较小.

  5. Calculating dose distributions and wedge factors for photon treatment fields with dynamic wedges based on a convolution/superposition method.

    Science.gov (United States)

    Liu, H H; McCullough, E C; Mackie, T R

    1998-01-01

    A convolution/superposition based method was developed to calculate dose distributions and wedge factors in photon treatment fields generated by dynamic wedges. This algorithm used a dual source photon beam model that accounted for both primary photons from the target and secondary photons scattered from the machine head. The segmented treatment tables (STT) were used to calculate realistic photon fluence distributions in the wedged fields. The inclusion of the extra-focal photons resulted in more accurate dose calculation in high dose gradient regions, particularly in the beam penumbra. The wedge factors calculated using the convolution method were also compared to the measured data and showed good agreement within 0.5%. The wedge factor varied significantly with the field width along the moving jaw direction, but not along the static jaw or the depth direction. This variation was found to be determined by the ending position of the moving jaw, or the STT of the dynamic wedge. In conclusion, the convolution method proposed in this work can be used to accurately compute dose for a dynamic or an intensity modulated treatment based on the fluence modulation in the treatment field.

  6. The evolving energy budget of accretionary wedges

    Science.gov (United States)

    McBeck, Jessica; Cooke, Michele; Maillot, Bertrand; Souloumiac, Pauline

    2017-04-01

    The energy budget of evolving accretionary systems reveals how deformational processes partition energy as faults slip, topography uplifts, and layer-parallel shortening produces distributed off-fault deformation. The energy budget provides a quantitative framework for evaluating the energetic contribution or consumption of diverse deformation mechanisms. We investigate energy partitioning in evolving accretionary prisms by synthesizing data from physical sand accretion experiments and numerical accretion simulations. We incorporate incremental strain fields and cumulative force measurements from two suites of experiments to design numerical simulations that represent accretionary wedges with stronger and weaker detachment faults. One suite of the physical experiments includes a basal glass bead layer and the other does not. Two physical experiments within each suite implement different boundary conditions (stable base versus moving base configuration). Synthesizing observations from the differing base configurations reduces the influence of sidewall friction because the force vector produced by sidewall friction points in opposite directions depending on whether the base is fixed or moving. With the numerical simulations, we calculate the energy budget at two stages of accretion: at the maximum force preceding the development of the first thrust pair, and at the minimum force following the development of the pair. To identify the appropriate combination of material and fault properties to apply in the simulations, we systematically vary the Young's modulus and the fault static and dynamic friction coefficients in numerical accretion simulations, and identify the set of parameters that minimizes the misfit between the normal force measured on the physical backwall and the numerically simulated force. Following this derivation of the appropriate material and fault properties, we calculate the components of the work budget in the numerical simulations and in the

  7. Earthquake occurrence processes in the Indo-Burmese wedge and Sagaing fault region

    Science.gov (United States)

    Kundu, Bhaskar; Gahalaut, V. K.

    2012-02-01

    Earthquakes in the Indo-Burmese wedge and Sagaing fault regions occur in response to the partitioning of the India-Sunda motion along these two distinct boundaries. Under the accretionary wedge of the Indo-Burmese arc, majority of the earthquakes occur in the depth range of 30-60 km and define an eastward gently dipping seismicity trend surface that coincides with the Indian slab. The dip of the slab steepens in the east direction and earthquakes occur down to a depth of 150 km, though the slab can be traced up to the 660 km discontinuity. Although these features are similar to a subduction zone, the nature of the earthquakes and our analysis of their focal mechanisms suggest that these earthquakes are of intra-slab type which occur on steep plane within the Indian plate and the sense of motion implies a northward relative motion with respect to the Sunda plate. Thus these earthquakes and the stress state do not support active subduction across the Indo-Burmese arc which is also consistent with the relative motion of India-Sunda plates. The absence of inter-plate earthquakes, lack of evidence of the occurrence of great earthquakes in the historical records and non-seismogenic nature of the plate interface under the accretionary wedge suggest that seismic hazard due to earthquakes along the plate boundary may be relatively low. However, major intra-slab earthquakes at shallow and intermediate depths may still cause damage in the sediment filled valley regions of Manipur and Cachar in India and Chittagong and Sylhet regions of Bangladesh. In the Sagaing fault region, earthquakes occur through dextral strike slip motion along the north-south oriented plane and the stress state is consistent with the plate motion across the Sagaing fault.

  8. Morphotectonics of the Padul-Nigüelas Fault Zone, southern Spain

    Directory of Open Access Journals (Sweden)

    Jochen Hürtgen

    2014-02-01

    Full Text Available The Padul-Nigüelas Fault Zone (PNFZ is situated at the south-western mountain front of the Sierra Nevada (southern Spain in the Internal Zone of the Betic Cordilleras and belongs to a NW-SE trending system of normal faults dipping SW. The PNFZ constitutes a major tectonic and lithological boundary in the Betics, and separates the metamorphic units of the Alpujárride Complex from Upper Tertiary to Quaternary deposits. Due to recent seismicity and several morphological and geological indicators, such as preserved fault scarps, triangular facets, deeply incised valleys and faults in the colluvial wedges, the PNFZ is suspected to be a tectonically active feature of the south-eastern Granada Basin. We performed morphotectonic GIS analyses based on digital elevation models (DEM, cell size: 10 m to obtain tectonic activity classes for each outcropping segment of the PNFZ. We have determined the following geomorphic indices: mountain front sinuosity, stream-length gradient index, concavity index and valley floor width to height ratio. The results show a differentiation in the states of activity along the fault zone strike. The western and eastern segments of the PNFZ indicate a higher tectonic activity compared to the center of the fault zone. We discuss and critically examine the comparability and reproducibility of geomorphic analyses, concluding that careful interpretation is necessary, if no ground-truthing can be performed.

  9. Implementation of enhanced dynamic wedge in the focus rtp system.

    Science.gov (United States)

    Miften, M; Wiesmeyer, M; Beavis, A; Takahashi, K; Broad, S

    2000-01-01

    The FOCUS RTP system implementation of Varian's enhanced dynamic wedge (EDW) is presented. Calculations of both dose distributions and wedge factors (WFs) are based on segmented treatment tables (STTs). Calculating dose requires a "transmission matrix" derived from an STT to model the modified fluence from the source. The dose calculation is then performed using either the Clarkson or convolution/superposition algorithms. An initial "primary dose/monitor unit (MU) fraction" WF estimate at the weight point of symmetric and asymmetric fields is calculated from the STT as the ratio of MU delivered on the axis of the weight point divided by total MU delivered for the treatment field. In our approach, we go beyond this initial estimate with a "scatter dose" correction. This requires measured 60 degrees WFs for 5 fields. Scatter corrections derived from measured WFs are interpolated for other wedge angles and field sizes in much the same way as arbitrary wedge angle STTs are derived from a "golden STT" using the "ratio of tangents" formalism. Dose comparisons with measured distributions show good agreement to within 3% or 3 mm for 6-MV beams and all EDW angles. Agreement with measurements to within 1% is obtained for WFs in all symmetric and asymmetric fields for 6- and 10-MV beams. For large wedge angles and field sizes, this represents a significant improvement over the 3% to 4% errors often observed using the MU fraction model alone.

  10. Temporal evolution of fO2 in the Mariana mantle wedge

    Science.gov (United States)

    Brounce, M. N.; Kelley, K. A.; Cottrell, E.

    2013-12-01

    The elevated oxygen fugacity (fO2) recorded by arc lavas appears to be linked to slab fluid influence globally and locally; however, many details regarding the capacity that slab fluids have to oxidize the mantle wedge remain unknown. At the time of subduction initiation, melts may be produced by a combination of decompression and fluid-fluxed melting and the role of flux melting may increase as the subduction zone matures (Reagan et al., 2010, G3 11(3)). Immediately prior to subduction initiation, the mantle presumably has fO2 and fluid concentrations similar to mid-ocean ridge (MOR) source mantle (near the quartz-fayalite-magnetite buffer, QFM, and relatively dry). As subduction zones mature, slab fluids may become more dominant in melt generation as evidenced by increases in fluid-mobile trace element signatures, but the fO2 of slab fluids and temporal changes in the fO2 of erupted basalt remains undocumented. The Mariana forearc southwest of Guam records the initiation of Pacific plate subduction (Reagan et al., 2010). At the base, fore-arc basalts (FAB) erupted at the immediate onset of subduction (51-52 Ma) show minor traces of slab fluid influence and likely reflect decompression melting that occurred as mantle rose to accommodate the sinking Pacific plate. The FAB are overlain by 37-44 Ma 'transitional' basalts whose fluid mobile trace element enrichments indicate that slab fluids have greater influence in their petrogenesis. These lavas provide the opportunity to directly constrain the timescales of mantle wedge oxidation during the initiation and maturation of an oceanic subduction zone. We present Fe3+/ΣFe ratios (μ-XANES) determined on FAB and transitional basalt glasses, paired with previously published major and trace element data. These glasses range in MgO from 2.75 - 7.56 wt% and have Fe3+/ΣFe ratios (0.171 - 0.208) that are slightly more oxidized than MORB (0.16), similar to Mariana trough lavas that reflect minor traces of slab fluid influence

  11. Triangle zone beer and bull May 11, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Newson, A. C.; Kubli, T. E.; Dechesne, R. G.; MacKay, P. E.; Reid, J. P.; Varsek, J. L.

    1996-06-01

    A review and a summing up of the papers contributed to this special issue of the Bulletin of Canadian Petroleum Geology on triangle zones was prepared in an informal `beer and bull` session by an ad hoc panel of contributors. There was no consensus as to the precise meaning, or the accuracy of the term `triangle zone`, although there was some agreement that if one wants to define structures with a roughly triangular shape, based on seismic expression alone, the term `wedge` might be more appropriate, since the focus of triangle zone development is tectonic activity creating a wedge that delaminates crust as it propagates towards the foreland. It was generally agreed (for now at least) that triangle zones are just one type of thrust front structure when viewed in the larger context of mountain belts around the world. In the classical sense, triangle zones appear to be restricted to the Alberta and Montana segment of the Cordilleran thrust belt. 1 ref.

  12. Casimir effect at nonzero temperature for wedges and cylinders

    CERN Document Server

    Ellingsen, Simen Å; Milton, Kimball A

    2010-01-01

    We consider the Casimir-Helmholtz free energy at nonzero temperature $T$ for a circular cylinder and perfectly conducting wedge closed by a cylindrical arc, either perfectly conducting or isorefractive. The energy expression at nonzero temperature may be regularized to obtain a finite value, except for a singular corner term in the case of the wedge which is present also at zero temperature. Assuming the medium in the interior of the cylinder or wedge be nondispersive with refractive index $n$, the temperature dependence enters only through the non-dimensional parameter $2\\pi naT$, $a$ being the radius of the cylinder or cylindrical arc. We show explicitly that the known zero temperature result is regained in the limit $aT\\to 0$ and that previously derived high temperature asymptotics for the cylindrical shell are reproduced exactly.

  13. Dislocation Nucleation and Pileup under a Wedge Contact at Nanoscale

    Directory of Open Access Journals (Sweden)

    Y. F. Gao

    2008-01-01

    Full Text Available Indentation responses of crystalline materials have been found to be radically different at micrometer and nanometer scales. The latter is usually thought to be controlled by the nucleation of dislocations. To explore this physical process, a dislocation mechanics study is performed to determine the conditions for the nucleation of a finite number of dislocations under a two-dimensional wedge indenter, using the Rice-Thomson nucleation criterion. The configurational force on the dislocation consists of the applied force, the image force, and the interaction force between dislocations. Dislocations reach equilibrium positions when the total driving force equals the effective Peierls stress, giving a set of nonlinear equations that can be solved using the Newton-Raphson method. When the apex angle of the wedge indenter increases, the critical contact size for dislocation nucleation increases rapidly, indicating that dislocation multiplication near a blunt wedge tip is extremely difficult. This geometric dependence agrees well with experimental findings.

  14. Modeling and Stability Analysis of Wedge Clutch System

    Directory of Open Access Journals (Sweden)

    Jian Yao

    2014-01-01

    Full Text Available A wedge clutch with unique features of self-reinforcement and small actuation force was designed. Its self-reinforcement feature, associated with different factors such as the wedge angle and friction coefficient, brings different dynamics and unstable problem with improper parameters. To analyze this system, a complete mathematical model of the actuation system is built, which includes the DC motor, the wedge mechanism, and the actuated clutch pack. By considering several nonlinear factors, such as the slip-stick friction and the contact or not of the clutch plates, the system is piecewise linear. Through the stability analysis of the linearized system in clutch slipping phase, the stable condition of the designed parameters is obtained as α>arctan⁡(μc. The mathematical model of the actuation system is validated by prototype testing. And with the validated model, the system dynamics in both stable and unstable conditions is investigated and discussed in engineering side.

  15. Tricritical wedge filling transitions with short-ranged forces

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Enrique, J M [Departamento de Fisica Atomica, Molecular y Nuclear, Area de Fisica Teorica, Universidad de Sevilla, Apartado de Correos 1065, 41080 Sevilla (Spain); Parry, A O [Department of Mathematics, Imperial College 180 Queen' s Gate, London SW7 2BZ (United Kingdom)

    2005-11-16

    We show that the 3D wedge filling transition in the presence of short-ranged interactions can be first order or second order depending on the strength of the line tension associated with the wedge bottom. This fact implies the existence of a tricritical point characterized by a short-distance expansion which differs from the usual continuous filling transition. Our analysis is based on an effective one-dimensional model for the 3D wedge filling, which arises from the identification of the breather modes as the only relevant interfacial fluctuations. From such analysis we find a correspondence between continuous 3D filling at bulk coexistence and 2D wetting transitions with random-bond disorder.

  16. Enhanced performance of fast-response 3-hole wedge probes for transonic flows in axial turbomachinery

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, D.; Paniagua, G. [von Karman Institute for Fluid Dynamics, Turbomachinery and Propulsion Department, Rhode-Saint-Genese (Belgium); Fernandez Oro, J.M. [Universidad de Oviedo, Area de Mecanica de Fluidos, Gijon (Spain); Denos, R. [European Commission, Directorate General for Research, Brussels (Belgium)

    2011-01-15

    The paper presents the development and application of a three-sensor wedge probe to measure unsteady aerodynamics in a transonic turbine. CFD has been used to perform a detailed uncertainty analysis related to probe-induced perturbations, in particular the separation zones appearing on the wedge apex. The effects of the Reynolds and Mach numbers are studied using both experimental data together with CFD simulations. The angular range of the probe and linearity of the calibration maps are enhanced with a novel zonal calibration technique, used for the first time in compressible flows. The data reduction methodology is explained and demonstrated with measurements performed in a single-stage high-pressure turbine mounted in the compression tube facility of the von Karman Institute. The turbine was operated at subsonic and transonic pressure ratios (2.4 and 5.1) for a Reynolds number of 10{sup 6}, representative of modern engine conditions. Complete maps of the unsteady flow angle and rotor outlet Mach number are documented. These data allow the study of secondary flows and rotor trailing edge shocks. (orig.)

  17. Enhanced performance of fast-response 3-hole wedge probes for transonic flows in axial turbomachinery

    Science.gov (United States)

    Delhaye, D.; Paniagua, G.; Fernández Oro, J. M.; Dénos, R.

    2011-01-01

    The paper presents the development and application of a three-sensor wedge probe to measure unsteady aerodynamics in a transonic turbine. CFD has been used to perform a detailed uncertainty analysis related to probe-induced perturbations, in particular the separation zones appearing on the wedge apex. The effects of the Reynolds and Mach numbers are studied using both experimental data together with CFD simulations. The angular range of the probe and linearity of the calibration maps are enhanced with a novel zonal calibration technique, used for the first time in compressible flows. The data reduction methodology is explained and demonstrated with measurements performed in a single-stage high-pressure turbine mounted in the compression tube facility of the von Karman Institute. The turbine was operated at subsonic and transonic pressure ratios (2.4 and 5.1) for a Reynolds number of 106, representative of modern engine conditions. Complete maps of the unsteady flow angle and rotor outlet Mach number are documented. These data allow the study of secondary flows and rotor trailing edge shocks.

  18. Restraint of fatigue crack growth by wedge effects of fine particles

    CERN Document Server

    Takahashi, I; Kotani, N

    2000-01-01

    Presents some experimental results which demonstrate restraint of fatigue crack growth in an Al-Mg alloy by wedge effects of fine particles. Fatigue test specimens were machined from a JIS A5083P-O Al-Mg alloy plate of 5 mm thickness and an EDM starter notch was introduced to each specimen. Three kinds of fine particles were prepared as the materials to be wedged into the fatigue cracks, i.e. magnetic particles and two kinds of alumina particles having different mean particle sizes of 47.3 mu m and 15.2 mu m. Particles of each kind were suspended in an oil to form a paste, which was applied on the specimen surface covering the notch zone prior to the fatigue tests. In order to make some fracture mechanics approaches, in situ observations of fatigue cracks were performed for the two cases using a CCD microscope, with a magnification of *1000. The crack length and the crack opening displacement (COD) at the notch root, delta , were measured. The crack retardation effect continues almost through the entire lifet...

  19. Flow Analysis for the Falkner–Skan Wedge Flow

    DEFF Research Database (Denmark)

    Bararnia, H; Haghparast, N; Miansari, M

    2012-01-01

    the constant coefficients in the approximated solution. The effects of the polynomial terms of HAM are considered and the accuracy of the results is shown, which increases with the increasing polynomial terms of HAM. Analytical results for the dimensionless velocity and temperature profiles of the wedge flow......In this article an analytical technique, namely the homotopy analysis method (HAM), is applied to solve the momentum and energy equations in the case of a two-dimensional incompressible flow passing over a wedge. The trail and error method and Padé approximation strategies have been used to obtain...

  20. Molecular Depth Profiling with Cluster SIMS and Wedges

    Science.gov (United States)

    Mao, Dan; Wucher, Andreas; Winograd, Nicholas

    2009-01-01

    Secondary ion mass spectrometry and atomic force microscopy are employed to characterize a wedge-shaped crater eroded by 40 keV C60+ bombardment of a 395-nm thin film of Irganox 1010 doped with four delta layers of Irganox 3114. The wedge structure creates a laterally magnified cross section of the film. From an examination of the resulting surface, information about depth resolution, topography and erosion rate can be obtained as a function of crater depth in a single experiment. This protocol provides a straightforward way to determine the parameters necessary to characterize molecular depth profiles, and to obtain an accurate depth scale for erosion experiments. PMID:19968247

  1. Surgical treatment of idiopathic syringomyelia: Silastic wedge syringosubarachnoid shunting technique

    Directory of Open Access Journals (Sweden)

    Teck M Soo

    2014-01-01

    Conclusions: Shunting procedures for the syringomyelia disease spectrum have been criticized due to the inconsistent long-term outcomes. This surgical technique used to treat symptomatic idiopathic syringomyelia has been devised based on our intraoperative experience, surgical outcomes, and evaluation of the literature. The purpose of the wedges is to preserve patency of the communication between the syrinx cavity and the expanded subarachnoid space by preventing healing of the myelotomy edges and by maintaining an artificial conduit between the syrinx cavity and the subarachnoid space. Although short-term results are promising, continued long-term follow up is needed to determine the ultimate success of the silastic wedge shunting procedure.

  2. Three-dimensional wedge filling in ordered and disordered systems

    Energy Technology Data Exchange (ETDEWEB)

    Greenall, M J [Department of Mathematics, Imperial College London, 180 Queen' s Gate, London SW7 2BZ (United Kingdom); Parry, A O [Department of Mathematics, Imperial College London, 180 Queen' s Gate, London SW7 2BZ (United Kingdom); Romero-Enrique, J M [Department of Mathematics, Imperial College London, 180 Queen' s Gate, London SW7 2BZ (United Kingdom)

    2004-04-21

    We investigate interfacial structural and fluctuation effects occurring at continuous filling transitions in 3D wedge geometries. We show that fluctuation-induced wedge covariance relations that have been reported recently for 2D filling and wetting have mean-field or classical analogues that apply to higher-dimensional systems. Classical wedge covariance emerges from analysis of filling in shallow wedges based on a simple interfacial Hamiltonian model and is supported by detailed numerical investigations of filling within a more microscopic Landau-like density functional theory. Evidence is presented that classical wedge covariance is also obeyed for filling in more acute wedges in the asymptotic critical regime. For sufficiently short-ranged forces mean-field predictions for the filling critical exponents and covariance are destroyed by pseudo-one-dimensional interfacial fluctuations. We argue that in this filling fluctuation regime the critical exponents describing the divergence of length scales are related to values of the interfacial wandering exponent {zeta}(d) defined for planar interfaces in (bulk) two-dimensional (d = 2) and three-dimensional (d = 3) systems. For the interfacial height l{sub w} {approx} {theta}-{alpha}){sup -{beta}}{sub w}, with {theta} the contact angle and {alpha} the wedge tilt angle, we find {beta}{sub w} = {zeta}(2)/2(1-{zeta}(3)). For pure systems (thermal disorder) we recover the known result {beta}{sub w} = 1/4 predicted by interfacial Hamiltonian studies whilst for random-bond disorder we predict the universal critical exponent {beta} {approx} even in the presence of dispersion forces. We revisit the transfer matrix theory of three-dimensional filling based on an effective interfacial Hamiltonian model and discuss the interplay between breather, tilt and torsional interfacial fluctuations. We show that the coupling of the modes allows the problem to be mapped onto a quantum mechanical problem as conjectured by previous authors

  3. Non-linear critical taper model and determination of accretionary wedge strength

    Science.gov (United States)

    Yang, Che-Ming; Dong, Jia-Jyun; Hsieh, Yuan-Lung; Liu, Hsueh-Hua; Liu, Cheng-Lung

    2016-12-01

    The critical taper model has been widely used to evaluate the strength contrast between the wedge and the basal detachment of fold-and-thrust belts and accretionary wedges. However, determination of the strength parameters using the traditional critical taper model, which adopts the Mohr-Coulomb failure criterion, is difficult, if not impossible. In this study, we propose a modified critical taper model that incorporates the non-linear Hoek-Brown failure criterion. The parameters in the proposed critical Hoek-Brown wedge CHBW model can be directly evaluated via field investigations and laboratory tests. Meanwhile, the wedge strength is a function of the wedge thickness, which is oriented from stress non-linearity. The fold-and-thrust belt in western central Taiwan was used as an example to validate the proposed model. The determined wedge strength was 0.86 using a representative wedge thickness of 5.3 km; this was close to the inferred value of 0.6 from the critical taper. Interestingly, a concave topographic relief is predicted as a result of the wedge thickness dependency of the wedge strength, even if the wedge is composed of homogeneous materials and if the strength of the detachment is uniform. This study demonstrates that the influence of wedge strength on the critical taper angle can be quantified by the spatial distribution of strength variables and by the consideration of the wedge thickness dependency of wedge strength.

  4. Benchmarking the Sandbox: Quantitative Comparisons of Numerical and Analogue Models of Brittle Wedge Dynamics (Invited)

    Science.gov (United States)

    Buiter, S.; Schreurs, G.; Geomod2008 Team

    2010-12-01

    When numerical and analogue models are used to investigate the evolution of deformation processes in crust and lithosphere, they face specific challenges related to, among others, large contrasts in material properties, the heterogeneous character of continental lithosphere, the presence of a free surface, the occurrence of large deformations including viscous flow and offset on shear zones, and the observation that several deformation mechanisms may be active simultaneously. These pose specific demands on numerical software and laboratory models. By combining the two techniques, we can utilize the strengths of each individual method and test the model-independence of our results. We can perhaps even consider our findings to be more robust if we find similar-to-same results irrespective of the modeling method that was used. To assess the role of modeling method and to quantify the variability among models with identical setups, we have performed a direct comparison of results of 11 numerical codes and 15 analogue experiments. We present three experiments that describe shortening of brittle wedges and that resemble setups frequently used by especially analogue modelers. Our first experiment translates a non-accreting wedge with a stable surface slope. In agreement with critical wedge theory, all models maintain their surface slope and do not show internal deformation. This experiment serves as a reference that allows for testing against analytical solutions for taper angle, root-mean-square velocity and gravitational rate of work. The next two experiments investigate an unstable wedge, which deforms by inward translation of a mobile wall. The models accommodate shortening by formation of forward and backward shear zones. We compare surface slope, rate of dissipation of energy, root-mean-square velocity, and the location, dip angle and spacing of shear zones. All models show similar cross-sectional evolutions that demonstrate reproducibility to first order. However

  5. Grounding Resistance Characteristics of Gravity Foundations of Offshore Wind Turbines in the Intertidal Zone%潮间带海上风电机组重力式基础接地特性

    Institute of Scientific and Technical Information of China (English)

    周蜜; 樊亚东; 郑钟楠; 王建国; 张宝全; 李显强

    2015-01-01

    Compared with onshore wind turbines, offshore wind turbine develops very quickly in recent years due to less land cover, higher wind speed and steady wind direction. At present, gravity foundations of offshore wind turbines are widely applied in Rudong intertidal wind farm in China. However, up to now, few attentions are paid to grounding of gravity foundations. In this paper, grounding resistance characteristics of gravity foundations of intertidal wind turbines were calculated and analyzed systematically. Various impact factors, including depth of seawater, resistivity and thickness of clay and gravel layers, and size and depth of pile pumped into ground, were considered. Analytical results show that grounding resistance is affected significantly by depth of seawater. If seawater depth is less than 0.3 m, power-frequency and impulse grounding resistances in intertidal zone of gravity foundation offshore turbine will, in some conditions, exceed limited value specified in standards. As seawater depth increases, both power-frequency and impulse grounding resistances decrease rapidly. Moreover, the two types of grounding resistances increase with increase of soil resistivity of clay and gravel layers, and decrease with increase of clay layer thickness, although these effects become weaker as depth of seawater increases. Structure size of gravity foundation, including its diameter and driven depth, has limited effect on resistances. These results are of great significance for grounding design of gravity foundations of offshore wind turbines.%为研究重力式基础海上风电机组接地特性,应用CDEGS仿真软件对重力式基础潮间带海上风电机组接地装置的工频特性参数和冲击特性参数进行了系统计算,讨论了海水深度、粘土层土壤电阻率及厚度、砂石层土壤电阻率以及基础结构尺寸参数对重力式基础工频接地电阻和冲击接地电阻的影响。结果表明:潮间带海水深度对潮间

  6. Evolution of a highly dilatant fault zone in the grabens of Canyonlands National Park, Utah/USA – integrating field work, ground penetrating radar and airborne imagery analysis

    Directory of Open Access Journals (Sweden)

    M. Kettermann

    2015-03-01

    Full Text Available The grabens of the Canyonlands National Park are a young and active system of sub-parallel, arcuate grabens, whose evolution is the result of salt movement in the subsurface and a slight regional tilt of the faulted strata. We present results of ground penetrating radar surveys in combination with field observations and analysis of high resolution airborne imagery. GPR data show intense faulting of the Quaternary sediments at the flat graben floors, implying a more complex fault structure than visible at the surface. Direct measurements of heave and throw at several locations to infer fault dips at depth, combined with observations of primary joint surfaces in the upper 100 m suggest a model of the highly dilatant fault geometry in profile. Sinkholes observed in the field as well as in airborne imagery give insights in local massive dilatancy and show where water and sediments are transported underground. Based on correlations of paleosols observed in outcrops and GPR profiles, we argue that the grabens in Canyonlands National Park are either older than previously assumed, or that sedimentation rates were much higher in the Pleistocene.

  7. Evolution of a highly dilatant fault zone in the grabens of Canyonlands National Park, Utah/USA - integrating field work, ground penetrating radar and airborne imagery analysis

    Science.gov (United States)

    Kettermann, M.; Grützner, C.; van Gent, H. W.; Urai, J. L.; Reicherter, K.; Mertens, J.

    2015-03-01

    The grabens of the Canyonlands National Park are a young and active system of sub-parallel, arcuate grabens, whose evolution is the result of salt movement in the subsurface and a slight regional tilt of the faulted strata. We present results of ground penetrating radar surveys in combination with field observations and analysis of high resolution airborne imagery. GPR data show intense faulting of the Quaternary sediments at the flat graben floors, implying a more complex fault structure than visible at the surface. Direct measurements of heave and throw at several locations to infer fault dips at depth, combined with observations of primary joint surfaces in the upper 100 m suggest a model of the highly dilatant fault geometry in profile. Sinkholes observed in the field as well as in airborne imagery give insights in local massive dilatancy and show where water and sediments are transported underground. Based on correlations of paleosols observed in outcrops and GPR profiles, we argue that the grabens in Canyonlands National Park are either older than previously assumed, or that sedimentation rates were much higher in the Pleistocene.

  8. Coupled stratigraphic and structural evolution of a glaciated orogenic wedge, offshore St. Elias orogen, Alaska

    Science.gov (United States)

    Worthington, Lindsay L.; Gulick, Sean P. S.; Pavlis, Terry L.

    2010-12-01

    The St. Elias orogen is the result of ˜10 Myr of oblique convergence and flat-slab subduction in the Gulf of Alaska between North America and the Yakutat microplate. Extensive glaciation and a complex tectonic environment make this region a unique case study in which to examine the details of terrane accretion and the possible coupled influence of climate and tectonic drivers on the structural and topographic evolution of an orogenic wedge. Reflection seismic profiles across the offshore Pamplona zone fold-thrust belt, the frontal St. Elias orogenic wedge, provide constraints for quantifying Pleistocene deformation recorded in the glaciomarine Yakataga formation. The total amount of Pleistocene shortening observed varies from ˜3 to 5 mm/yr, compared to the current GPS-derived Yakutat-North America convergence rate across the St. Elias orogen of ˜45 mm/yr. Growth strata and kinematic fold analysis allow comparison of relative timing of fault activity, which reveals temporal and spatial shifting of active deformation during the glacial period: faulting localized adjacent to the coastline and at the current submarine deformation front. The abandoned, currently inactive region is colocated with the major glacial depocenter in the region, the Bering Trough. These observations imply that glacial processes such as sediment loading and focused erosion during advance-retreat cycles has a direct effect on the evolution of individual faults within the Pamplona zone and the overall deformation pattern in the offshore St. Elias margin. This information provides key constraints for understanding how climatic shifts may have affected the evolution of margin architecture during Pleistocene glacial-interglacial periods.

  9. Field observations of climbing behavior and seed predation by adult ground beetles (Coleoptera: Carabidae) in a lowland area of the temperate zone.

    Science.gov (United States)

    Sasakawa, Kôji

    2010-10-01

    Granivory is a specialized food habit in the predominantly carnivorous beetle family Carabidae. Most studies of carabid granivory have been conducted under laboratory conditions; thus, our knowledge of the feeding ecology of granivorous carabids in the field is insufficient. I conducted field observations of climbing behavior and seed predation by adult carabids in a lowland area of eastern Japan, from early October to late November in 2008. This is the first systematic field observation of the feeding ecology of granivorous carabids in the temperate zone. In total, 176 carabid individuals of 11 species were observed, with 108 individuals feeding on plant seeds/flowers. Each carabid species was primarily observed feeding on a particular plant species. Frequently observed combinations were: Amara gigantea Motschulsky on Humulus scandens (Loureiro) Merrill (Moraceae) seed, Amara lucens Baliani on Artemisia indica Willdenow (Asteraceae) flower, and Amara macronota (Solsky) and Harpalus (Pseudoophonus) spp. on Digitaria ciliaris (Retzius) Koeler (Poaceae) seed. In all but one species, the sex ratio of individuals observed feeding was female-biased. In Am. gigantea and Am. macronota, a larger proportion of females than males ate seeds. In the three Amara species, copulations on plants, with the female feeding on its seeds/flowers, were often observed. These observations may indicate that, whereas females climb onto plants to feed on seeds, males climb to seek females for copulation rather than forage. Because granivorous carabids play important roles as weed-control agents in temperate agro-ecosystems, the present results would provide valuable basic information for future studies on this subject.

  10. Erosional Reduction of an Orogenic Wedge: Structural Response to Neogene Climate Change within the St. Elias Orogen, Alaska

    Science.gov (United States)

    Berger, A. L.; Spotila, J. A.; Chapman, J. B.; Pavlis, T. L.; Enkelmann, E.; Buscher, J. T.

    2007-12-01

    The kinematics and architecture of orogenic systems may be heavily influenced by climate, but little research has focused on the long term effects of glacial erosion on orogenesis. Apatite and zircon (U-Th)/He thermochronometry on >75 bedrock samples across the St. Elias orogen, one of the best examples of a glaciated orogenic wedge, is the basis for a new kinematic model and demonstrates an association between glacial denudation and orogenic architecture. The spatial pattern of low temperature cooling indicates that exhumation and deformation are focused within a thin-skinned fold and thrust belt on the windward flank, whereas the leeward flank of the orogen functions as a deformational backstop. A previously unrecognized structure beneath the Bagley ice field must separate these domains with south-side-up motion. We propose this structure is a backthrust making the orogen doubly-vergent. Suggestive of accelerated backthrust motion in response to climate change, cooling rates within the hanging wall block and across the entire windward flank of the orogen accelerated ten-fold coeval with enhanced glaciation. As backthrust motion increased, glacial unroofing also coincided with a regional shift in deformation away from prominent forethrusts including the North American-Yakutat terrane suture (Chugach St. Elias fault) and the seaward deformation front (Pamplona zone). Across the windward flank of the orogen, exhumation, at rates of up to 5 mm/yr, is focused within a narrow zone, where the glacial equilibrium line altitude (ELA) intersects the orogenic wedge. This zone of rapid exhumation, not present prior to the onset of enhanced glaciation, cuts across the structural trend of the orogen and is more narrowly focused than orographic precipitation. Accelerated denudation at the ELA thus appears to have redistributed strain along a series of forethrusts that lie at the zone of heaviest glacial flux, while the backthrust progressively truncates the southward

  11. locally fabricated metal step wedge for quality assurance in ...

    African Journals Online (AJOL)

    DR. AMINU

    materials, as well as to investigate an alternative wedge material. The values of the ... The use of low performance x-ray machines. b. ... machine in the Radiology Department of. JUTH is .... the x-ray beam, while ms determines the interaction.

  12. Thoracoscopic pulmonary wedge resection without post-operative chest drain

    DEFF Research Database (Denmark)

    Holbek, Bo Laksafoss; Hansen, Henrik Jessen; Kehlet, Henrik

    2016-01-01

    : Forced expiratory volume in 1 s (FEV1) ≥60 % of expected, FEV1/forced vital capacity ≥70 %, tumour diameter ≤2 cm, distance from tumour to visceral pleura ≤3 cm, ≤2 separate wedges, no air leak on an intraoperative air leakage test and absence of severe adhesions, bullous/emphysematous disease, pleural...

  13. Wedges, Cones, Cosmic Strings, and the Reality of Vacuum Energy

    CERN Document Server

    Fulling, S A; Truong, P N; Wagner, J

    2012-01-01

    One of J. Stuart Dowker's most significant achievements has been to observe that the theory of diffraction by wedges developed a century ago by Sommerfeld and others provided the key to solving two problems of great interest in general-relativistic quantum field theory during the last quarter of the twentieth century: the vacuum energy associated with an infinitely thin, straight cosmic string, and (after an interchange of time with a space coordinate) the apparent vacuum energy of empty space as viewed by an accelerating observer. In a sense the string problem is more elementary than the wedge, since Sommerfeld's technique was to relate the wedge problem to that of a conical manifold by the method of images. Indeed, Minkowski space, as well as all cone and wedge problems, are related by images to an infinitely sheeted master manifold, which we call Dowker space. We review the research in this area and exhibit in detail the vacuum expectation values of the energy density and pressure of a scalar field in Dowk...

  14. Discrete dislocation plasticity analysis of the wedge indentation of films

    NARCIS (Netherlands)

    Balint, D. S.; Deshpande, V. S.; Needleman, A.; Van der Giessen, E.

    2006-01-01

    The plane strain indentation of single crystal films on a rigid substrate by a rigid wedge indenter is analyzed using discrete dislocation plasticity. The crystals have three slip systems at +/- 35.3 degrees and 90 degrees with respect to the indentation direction. The analyses are carried out for

  15. Fixed Points of Maps of a Nonaspherical Wedge

    Directory of Open Access Journals (Sweden)

    Merrill Keith

    2009-01-01

    Full Text Available Abstract Let be a finite polyhedron that has the homotopy type of the wedge of the projective plane and the circle. With the aid of techniques from combinatorial group theory, we obtain formulas for the Nielsen numbers of the selfmaps of .

  16. Magnetic and structural instabilities of ultrathin Fe(100) wedges

    Energy Technology Data Exchange (ETDEWEB)

    Bader, S.D.; Li, Dongqi; Qiu, Z.Q.

    1994-05-01

    An overview is provided of recent efforts to explore magnetic and related structural issues for ultrathin Fe films grown epitaxially as wedge structures onto Ag(100) and Cu(100). Experiments were carried out utilizing the surface magneto-optic Kerr effect (SMOKE). Ordinary bcc Fe is lattice-matched to the primitive unit cell of the Ag(100) surface. Fe wedges on Ag(100) can be fabricated whose thick end has in-plane magnetic easy axes due to the shape anisotropy, and whose thin end has perpendicular easy axes due to the surface magnetic anisotrophy. A spin-reorientation transition can thus be studied in the center of the wedge where the competing anisotropies cancel. The goal is to test the Mermin-Wagner theorem which states that long-range order is lost at finite temperatures in an isotropic two-dimensional Heisenberg system. Fe wedges on Cu(100) can be studied in like manner, but the lattice matching permits fcc and tetragonally-distorted fcc phases to provide structural complexity in addition to the interplay of competing magnetic anisotropies. The results of these studies are new phase identifications that help both to put previous work into perspective and to define issues to pursue in the future.

  17. The Influence of Localized Glacial Erosion on Exhumation Paths in Accreting Coulomb Wedges: Insights from Particle Velocimetry Analysis of Sandbox Models

    Science.gov (United States)

    Newman, P. J.; Davis, K.; Haq, S. S. B.; Ridgway, K.

    2015-12-01

    Glacial erosion can have an impact on the location and development of faults in mountain belts. The rapid removal and deposition of rock, in some cases, is thought to affect the initiation of slip on older fault structures, or cause the development of new structures within the older part of the wedge. We present cross-sectional data from both erosional and non-erosional sandbox models of Coulomb wedges in order to quantify the impact of localized erosion on the location of and slip on deformational structures, as well as the general path of material through a wedge. To do this, we employ Lagrangian particle tracking velocimetry (PTV) using the open-source Python PTV toolkit trackpy, among a suite of other data analysis tools. We are able to extract robust and reliable sets of particle trajectories from a series of images without the need for predefined markers or marker-beds, instead identifying and tracking natural variations in sand color as individual particles. By comparing the motion of particles in cross-section to the local surface topography over an entire experiment, we determine a high-resolution record of exhumation rates, in addition to simple uplift rates. These comparisons are further informed by the use of high-definition Eulerian particle image velocimetry (PIV), which provides quantitative data about the distribution of deformation and instantaneous material displacements throughout a cross-sectional view of a Coulomb wedge. This allows us to interpret these pathways in relation to the behavior of active structures and general wedge morphology. In our experiments, we observe that localized glacial erosion has an impact on material pathways, in the form of an increased rate of exhumation locally, more vertical trajectories towards surface below the zone of erosion, and reactivation of older structures to maintain force balance within the entire wedge.

  18. Thrust fault growth within accretionary wedges: New Insights from 3D seismic reflection data

    Science.gov (United States)

    Orme, H.; Bell, R. E.; Jackson, C. A. L.

    2015-12-01

    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. Previous studies have reported en-echelon thrust fault geometries from the NW part of the dataset, and have related this complex structure to seamount subduction. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. We also demonstrate that the majority of faults grew upward from the décollement, although there is some evidence for downward fault propagation. Our observations

  19. Big mantle wedge, anisotropy, slabs and earthquakes beneath the Japan Sea

    Science.gov (United States)

    Zhao, Dapeng

    2017-09-01

    The Japan Sea is a part of the western Pacific trench-arc-backarc system and has a complex bathymetry and intense seismic activities in the crust and upper mantle. Local seismic tomography revealed strong lateral heterogeneities in the crust and uppermost mantle beneath the eastern margin of the Japan Sea, which was determined using P and S wave arrival times of suboceanic earthquakes relocated precisely with sP depth phases. Ambient-noise tomography revealed a thin crust and a thin lithosphere beneath the Japan Sea and significant low-velocity (low-V) anomalies in the shallow mantle beneath the western and eastern margins of the Japan Sea. Observations with ocean-bottom seismometers and electromagnetometers revealed low-V and high-conductivity anomalies at depths of 200-300 km in the big mantle wedge (BMW) above the subducting Pacific slab, and the anomalies are connected with the low-V zone in the normal mantle wedge beneath NE Japan, suggesting that both shallow and deep slab dehydrations occur and contribute to the arc and back-arc magmatism. The Pacific slab has a simple geometry beneath the Japan Sea, and earthquakes occur actively in the slab down to a depth of ∼600 km beneath the NE Asian margin. Teleseismic P and S wave tomography has revealed that the Philippine Sea plate has subducted aseismically down to the mantle transition zone (MTZ, 410-660 km) depths beneath the southern Japan Sea and the Tsushima Strait, and a slab window is revealed within the aseismic Philippine Sea slab. Seismic anisotropy tomography revealed a NW-SE fast-velocity direction in the BMW, which reflects corner flows induced by the fast deep subduction of the Pacific slab. Large deep earthquakes (M > 7.0; depth > 500 km) occur frequently beneath the Japan Sea western margin, which may be related to the formation of the Changbai and Ulleung intraplate volcanoes. A metastable olivine wedge is revealed within the cold core of the Pacific slab at the MTZ depth, which may be related

  20. Wedges, cones, cosmic strings and their vacuum energy

    Science.gov (United States)

    Fulling, S. A.; Trendafilova, C. S.; Truong, P. N.; Wagner, J.

    2012-09-01

    One of J Stuart Dowker’s most significant achievements has been to observe that the theory of diffraction by wedges developed a century ago by Sommerfeld and others provided the key to solving two problems of great interest in general-relativistic quantum field theory during the last quarter of the 20th century: the vacuum energy associated with an infinitely thin, straight cosmic string, and (after an interchange of time with a space coordinate) the apparent vacuum energy of empty space as viewed by an accelerating observer. In a sense the string problem is more elementary than the wedge, since Sommerfeld’s technique was to relate the wedge problem to that of a conical manifold by the method of images. Indeed, Minkowski space, as well as all cone and wedge problems, are related by images to an infinitely sheeted master manifold, which we call Dowker space. We review the research in this area and exhibit in detail the vacuum expectation values of the energy density and pressure of a scalar field in Dowker space and the cone and wedge spaces that result from it. We point out that the (vanishing) vacuum energy of Minkowski space results, from the point of view of Dowker space, from the quantization of angular modes, in precisely the way that the Casimir energy of a toroidal closed universe results from the quantization of Fourier modes; we hope that this understanding dispels any lingering doubts about the reality of cosmological vacuum energy. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker’s 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’.

  1. Advances in monitoring dynamic hydrologic conditions in the vadose zone through automated high-resolution ground-penetrating radar imaging and analysis

    Science.gov (United States)

    Mangel, Adam R.

    This body of research focuses on resolving physical and hydrological heterogeneities in the subsurface with ground-penetrating radar (GPR). Essentially, there are two facets of this research centered on the goal of improving the collective understanding of unsaturated flow processes: i) modifications to commercially available equipment to optimize hydrologic value of the data and ii) the development of novel methods for data interpretation and analysis in a hydrologic context given the increased hydrologic value of the data. Regarding modifications to equipment, automation of GPR data collection substantially enhances our ability to measure changes in the hydrologic state of the subsurface at high spatial and temporal resolution (Chapter 1). Additionally, automated collection shows promise for quick high-resolution mapping of dangerous subsurface targets, like unexploded ordinance, that may have alternate signals depending on the hydrologic environment (Chapter 5). Regarding novel methods for data inversion, dispersive GPR data collected during infiltration can constrain important information about the local 1D distribution of water in waveguide layers (Chapters 2 and 3), however, more data is required for reliably analyzing complicated patterns produced by the wetting of the soil. In this regard, data collected in 2D and 3D geometries can further illustrate evidence of heterogeneous flow, while maintaining the content for resolving wave velocities and therefore, water content. This enables the use of algorithms like reflection tomography, which show the ability of the GPR data to independently resolve water content distribution in homogeneous soils (Chapter 5). In conclusion, automation enables the non-invasive study of highly dynamic hydrologic processes by providing the high resolution data required to interpret and resolve spatial and temporal wetting patterns associated with heterogeneous flow. By automating the data collection, it also allows for the novel

  2. Fast optical 3D form measurement of aspheres including determination of thickness and wedge and decenter errors

    Science.gov (United States)

    Stover, E.; Berger, G.; Wendel, M.; Petter, J.

    2015-10-01

    A method for non-contact 3D form testing of aspheric surfaces including determination of decenter and wedge errors and lens thickness is presented. The principle is based on the absolute measurement capability of multi-wavelength interferometry (MWLI). The approach produces high density 3D shape information and geometric parameters at high accuracy in short measurement times. The system allows inspection of aspheres without restrictions in terms of spherical departures, of segmented and discontinuous optics. The optics can be polished or ground and made of opaque or transparent materials.

  3. Vertebral Osteotomies in Ankylosing Spondylitis-Comparison of Outcomes Following Closing Wedge Osteotomy versus Opening Wedge Osteotomy: A Systematic Review.

    Science.gov (United States)

    Ravinsky, Robert A; Ouellet, Jean-Albert; Brodt, Erika D; Dettori, Joseph R

    2013-04-01

    Study Design Systematic review. Study Rationale To seek out and assess the best quality evidence available comparing opening wedge osteotomy (OWO) and closing wedge osteotomy (CWO) in patients with ankylosing spondylitis to determine whether their results differ with regard to several different subjective and objective outcome measures. Objective The aim of this study is to determine whether there is a difference in subjective and objective outcomes when comparing CWO and OWO in patients with ankylosing spondylitis suffering from clinically significant thoracolumbar kyphosis with respect to quality-of-life assessments, complication risks, and the amount of correction of the spine achieved at follow-up. Methods A systematic review was undertaken of articles published up to July 2012. Electronic databases and reference lists of key articles were searched to identify studies comparing effectiveness and safety outcomes between adult patients with ankylosing spondylitis who received closing wedge versus opening wedge osteotomies. Studies that included pediatric patients, polysegmental osteotomies, or revision procedures were excluded. Two independent reviewers assessed the strength of evidence using the GRADE criteria and disagreements were resolved by consensus. Results From a total of 67 possible citations, 4 retrospective cohorts (class of evidence III) met our inclusion criteria and form the basis for this report. No differences in Oswestry Disability Index, visual analog scale for pain, Scoliosis Research Society (SRS)-24 score, SRS-22 score, and patient satisfaction were reported between the closing and opening wedge groups across two studies. Regarding radiological outcomes following closing versus opening osteotomies, mean change in sagittal vertical axis ranged from 8.9 to 10.8 cm and 8.0 to 10.9 cm, respectively, across three studies; mean change in lumbar lordosis ranged from 36 to 47 degrees and 19 to 41 degrees across four studies; and mean change

  4. Characterized Fault Model of Scenario Earthquake Caused by the Itoigawa-Shizuoka Tectonic Line Fault Zone in Central Japan and Strong Ground Motion Prediction

    Science.gov (United States)

    Sato, T.; Dan, K.; Irikura, K.; Furumura, M.

    2001-12-01

    Based on the existing ideas on characterizing complex fault rupture process, we constructed four different characterized fault models for predicting strong motions from the most likely scenario earthquake along the active fault zone of the Itoigawa-Shizuoka Tectonic Line in central Japan. The Headquarters for Earthquake Research Promotion in Japanese government (2001) estimated that the earthquake (8 +/- 0.5) has the total fault length of 112 km with four segments. We assumed that the characterized fault model consisted of two regions: asperity and background (Somerville et al., 1999; Irikura, 2000; Dan et al., 2000). The main differences in the four fault models were 1) how to determine a seismic moment Mo from a fault rupture area S, 2) number of asperities N, 3) how to determine a stress parameter σ , and 4) fmax. We calculated broadband strong motions at three stations near the fault by a hybrid method of the semi-empirical and theoretical approaches. A comparison between the results from the hybrid method and those from empirical attenuation relations showed that the hybrid method using the characterized fault model could evaluate near-fault rupture directivity effects more reliably than the empirical attenuation relations. We also discussed the characterized fault models and the strong motion characteristics. The Mo extrapolated from the empirical Mo-S relation by Somerville et al. (1999) was a half of that determined from the mean value of the Wells and Coppersmith (1994) data. The latter Mo was consistent with that for the 1891 Nobi, Japan, earthquake whose fault length was almost the same as the length of the target earthquake. In addition, the fault model using the latter Mo produced a slip amount of about 6 m on the largest asperity, which was consistent with the displacement of 6 m to 9 m per event obtained from a trench survey. High-frequency strong motions were greatly influenced by the σ for the asperities (188 bars, 246 bars, 108 bars, and 134

  5. Comparison of clinical and radiological outcomes between opening-wedge and closing-wedge high tibial osteotomy: A comprehensive meta-analysis

    Science.gov (United States)

    Wu, Lingfeng; Lin, Jun; Jin, Zhicheng; Cai, Xiaobin; Gao, Weiyang

    2017-01-01

    High tibial osteotomy (HTO) has been widely used for clinical treatment of osteoarthritis of the medial compartment of the knee, and both opening-wedge and closing-wedge HTO are the most commonly used methods. However, it remains unclear which technique has better clinical and radiological outcomes in practice. To systematically evaluate this issue, we conducted a comprehensive meta-analysis by pooling all available data for the opening-wedge HTO and closing-wedge HTO techniques from the electronic databases including PubMed, Embase, Wed of Science and Cochrane Library. A total of 22 studies encompassing 2582 cases were finally enrolled in the meta-analysis. There was no significant difference regarding surgery time, duration of hospitalization, knee pain VAS, Lysholm score and HSS knee score (clinical outcomes) between the opening-wedge and closing-wedge HTO groups (P > 0.05). However, the opening-wedge HTO group showed wider range of motion than the closing-wedge HTO group (P = 0.003). Moreover, as for Hip-Knee-Ankle angle and mean angle of correction, no significant difference was observed between the opening-wedge and closing-wedge HTO groups (P > 0.05), while the opening-wedge HTO group showed greater posterior tibial slope angle (P < 0.001) and lesser patellar height than the closing-wedge HTO group (P < 0.001). On light of the above analysis, we believe that individualized surgical approach should be introduced based on the clinical characteristics of each patient. PMID:28182736

  6. The role of aerothermochemistry in double cone and double wedge flows

    Science.gov (United States)

    Swantek, Andrew

    In this work, hypervelocity flows over double cone and double wedge geometries are studied. The flow configurations established over the double cone/double wedge models are extremely sensitive to thermochemistry, and thus serve as ideal benchmarks for validating chemical models. The goals of this research are: i) to investigate the coupling between the fluid mechanics and thermochemistry in these flow fields by varying freestream flow composition and enthalpy, ii) to implement a diagnostic suite for time-resolved surface and freestream measurements, iii) to investigate the nature of flow field unsteadiness across various test conditions, and lastly iv) to extend the experimental database for shock wave boundary/layer interactions. An expansion tube is used to generate flows with enthalpies ranging from 2.2-8.0 MJ/kg (2-4 km/s) and Mach numbers from 4-7. The expansion tube is a novel impulse facility for accelerating a test gas to these velocities, while maintaining a minimally dissociated freestream. Additionally, the facility allows variation of the freestream composition (between nitrogen and air), while maintaining freestream test parameters (Mach number, density, enthalpy) to within 0.5%. Two models are used: a 25-55 degree double cone model and a 30-55 degree double wedge. There are four diagnostic components to this research which aim to enable a better understanding of these canonical flow fields. Single frame, high resolution schlieren photography is used to visualize various flow features including: the separation zone formed in the corner, the triple point interaction, and a supersonic shear layer. From these images, a separation zone length scaling parameter is determined. This parameter, derived for wedge geometries, is successfully applied to conical geometries by using a judicious choice of flow properties for scaling. In the wedge image series, nitrogen test conditions exhibit a distinct increase in bow shock standoff distance. Additionally, aft

  7. Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge

    Science.gov (United States)

    Vidale, John E.; Schmidt, David A.; Malone, Stephen D.; Hotovec-Ellis, Alicia J.; Moran, Seth C.; Creager, Kenneth C.; Houston, Heidi

    2014-01-01

    Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DLPs elsewhere along the arc suggests that localized heating may be dehydrating the serpentinized mantle wedge at these latitudes and causing DLPs by dehydration embrittlement. Higher heat flow in this region could be introduced by anomalously hot mantle, associated with the western migration of volcanism across the High Lava Plains of eastern Oregon, entrained in the corner flow proximal to the mantle wedge. Alternatively, fluids rising from the subducting slab through the mantle wedge may be the source of offset DLPs. As far as we know, these are among the first DLPs to be observed in the fore arc of a subduction-zone system.

  8. New age control on a mid-shelf grounding event in Eastern Basin, Ross Sea

    Science.gov (United States)

    Cone, A. N.; Bart, P. J.

    2009-12-01

    It is widely accepted that the West Antarctic Ice Sheet (WAIS) was grounded at the continental shelf edge in the eastern Ross Sea during the Last Glacial Maximum (LGM), but the precise chronology is debated. Post-LGM ice retreat chronologies have been developed using radiocarbon dating, mainly of acid-insoluble organics (AIO). Foraminifer tests yield more accurate radiocarbon dates than AIO because forams are less likely to be contaminated by allochthonous carbon, but unfortunately forams are sparse in Antarctic marine sediment cores. Here we show four consistent radiocarbon dates from forams in cored intervals within the foreset of a mid-continental-shelf grounding-zone wedge in Eastern Basin, Ross Sea. Our new radiocarbon dates reveal that the WAIS was grounded on the mid continental shelf circa 32,000 14C yr B.P., suggesting that retreat from this position began more than 10,000 years prior to the maximum sea level fall and global cooling associated with LGM. The dates contradict previous studies, which concluded that the WAIS was at its maximum shelf edge extent during LGM.

  9. Slab-derived halogens and noble gases illuminate closed system processes controlling volatile element transport into the mantle wedge

    Science.gov (United States)

    Kobayashi, Masahiro; Sumino, Hirochika; Nagao, Keisuke; Ishimaru, Satoko; Arai, Shoji; Yoshikawa, Masako; Kawamoto, Tatsuhiko; Kumagai, Yoshitaka; Kobayashi, Tetsuo; Burgess, Ray; Ballentine, Chris J.

    2017-01-01

    Halogen and noble gas systematics are powerful tracers of volatile recycling in subduction zones. We present halogen and noble gas compositions of mantle peridotites containing H2O-rich fluid inclusions collected at volcanic fronts from two contrasting subduction zones (the Avacha volcano of Kamchatka arc and the Pinatubo volcano of Luzon arcs) and orogenic peridotites from a peridotite massif (the Horoman massif, Hokkaido, Japan) which represents an exhumed portion of the mantle wedge. The aims are to determine how volatiles are carried into the mantle wedge and how the subducted fluids modify halogen and noble gas compositions in the mantle. The halogen and noble gas signatures in the H2O-rich fluids are similar to those of marine sedimentary pore fluids and forearc and seafloor serpentinites. This suggests that marine pore fluids in deep-sea sediments are carried by serpentine and supplied to the mantle wedge, preserving their original halogen and noble gas compositions. We suggest that the sedimentary pore fluid-derived water is incorporated into serpentine through hydration in a closed system along faults at the outer rise of the oceanic, preserving Cl/H2O and 36Ar/H2O values of sedimentary pore fluids. Dehydration-hydration process within the oceanic lithospheric mantle maintains the closed system until the final stage of serpentine dehydration. The sedimentary pore fluid-like halogen and noble gas signatures in fluids released at the final stage of serpentine dehydration are preserved due to highly channelized flow, whereas the original Cl/H2O and 36Ar/H2O ratios are fractionated by the higher incompatibility of halogens and noble gases in hydrous minerals.

  10. New machining and testing method of large angle infrared wedge mirror parts

    Science.gov (United States)

    Su, Ying; Guo, Rui; Zhang, Fumei; Zhang, Zheng; Liu, Xuanmin; Zengqi, Xu; Li, Wenting; Zhang, Feng

    2016-10-01

    Large angle wedge parts were widely used in the optical system that was used for achieving a wide range of scanning. Due to the parts having the characteristic of large difference in the thickness of both ends and high density, the accuracy of the wedge angle was hard to ensure to reach second level in optical processing. Generally, wedge mirror angle was measured by contact comparison method which was easy to damage the surface. In view of the existence of two practical problems, in this paper, based on theoretical analysis, by taking three key measures that were the accurate positioning for the central position of the large angle wedge part, the accuracy control of angle precision machined of wedge mirror and fast and non destructive laser assisted absolute measurement of large angle wedge, the qualified rate of parts were increased to 100%, a feasible, controllable and efficient process route for large angle infrared wedge parts was found out.

  11. Electrodynamic Casimir Effect in a Medium-Filled Wedge II

    CERN Document Server

    Ellingsen, Simen Adnoy; Milton, Kimball A

    2009-01-01

    We consider the Casimir energy in a geometry of an infinite magnetodielectric wedge closed by a circularly cylindrical arc embedded in another magnetodielectric medium, under the condition that the speed of light be the same in both media. An expression for the Casimir energy corresponding to the arc is obtained and it is found that in the limit where the reflectivity of the boundaries tends to unity the finite part of the Casimir energy of a perfectly conducting wedge-shaped sheet closed by a circular cylinder is regained. The energy of the latter geometry possesses divergences due to the presence of sharp corners. We argue how this is a pathology of the assumption of ideal conductor boundaries, and that no analogous term enters in the present geometry.

  12. MHD Casson nanofluid flow past a wedge with Newtonian heating

    Science.gov (United States)

    Ahmad, Kartini; Hanouf, Zahir; Ishak, Anuar

    2017-02-01

    The problem of steady Casson nanofluid flow past a wedge is studied in this paper. The presence of magnetic field along with Newtonian heating at the surface is considered. The governing partial differential equations are first transformed into a set of nonlinear ordinary differential equations by similarity transformations, before being solved numerically using the Keller-box method. The effects of the wedge angle Ω from 0° (horizontal plate) to 180° (vertical plate) as well as of as the magnetic parameter M on the non-Newtonian fluid flow and heat transfer characteristics are investigated. It is found that the surface temperature is slightly higher for the flow over a horizontal plate compared to that over a vertical plate. It is also found that the magnetic field decreases the surface temperature but increases the skin friction. The flow of a Newtonian fluid is found to give higher skin friction as compared to that of Casson fluid.

  13. Wedge Diffraction as an Instance of Radiative Shielding

    CERN Document Server

    Grzesik, J A

    2016-01-01

    The celebrated Sommerfeld wedge diffraction solution is reexamined from a null interior field perspective. Exact surface currents provided by that solution, when considered as disembodied half-plane laminae radiating into an ambient, uniform space both inside and outside the wedge proper, do succeed in reconstituting both a specular, mirror field above the exposed face, and a shielding plane-wave field of a sign opposite to that of the incoming excitation which, under superposition, creates both the classical, geometric-optics shadow, and a strictly null interior field at the dominant, plane-wave level. Both mirror and shadow radiated fields are controlled by the residue at just one simple pole encountered during a spectral radiative field assembly, fixed in place by incidence direction $\\phi_{0}$ as measured from the exposed face. The radiated fields further provide diffractive contributions drawn from two saddle points that track observation angle $\\phi.$ Even these, more or less asymptotic contributions, a...

  14. Direct FVM Simulation for Sound Propagation in an Ideal Wedge

    Directory of Open Access Journals (Sweden)

    Hongyu Ji

    2016-01-01

    Full Text Available The sound propagation in a wedge-shaped waveguide with perfectly reflecting boundaries is one of the few range-dependent problems with an analytical solution. This provides a benchmark for the theoretical and computational studies on the simulation of ocean acoustic applications. We present a direct finite volume method (FVM simulation for the ideal wedge problem, and both time and frequency domain results are analyzed. We also study the broadband problem with large-scale parallel simulations. The results presented in this paper validate the accuracy of the numerical techniques and show that the direct FVM simulation could be applied to large-scale complex acoustic applications with a high performance computing platform.

  15. Wedge Splitting Test and Fracture Energy on Particulate Reinforced Composites

    Energy Technology Data Exchange (ETDEWEB)

    Na, Seong Hyeon; Kim, Jae Hoon; Choi, Hoon Seok [Chungnam National Univ., Daejeon (Korea, Republic of); Park, Jae Beom; Kim, Shin Hoe; Jung, Gyoo Dong [Agency for Defense Developmen, Daejeon (Korea, Republic of)

    2016-03-15

    The effect of temperature on the fracture energy, crack propagation, and crack tip opening displacement(CTOD) was determined for particulate reinforced composites using the wedge splitting test. The materials that were used consisted of a polymer binder, an oxidizing agent, and aluminum particles. The test rate of the wedge splitting specimen was 50 mm/min, the temperature conditions were 50℃, room temperature, -40℃, and -60℃. The fracture energy, calculated from splitting load-crack mouth opening displacement(CMOD) curves, increased with decreasing temperature from 50℃ to -40℃. In addition, the strength of the particulate reinforced composites increased sharply at -60℃, and the composites evidenced brittle fracture due to the glass transition temperature. The strain fields near the crack tip were analyzed using digital image correlation.

  16. Modal Analysis in Lined Wedge-Shaped Ducts

    Science.gov (United States)

    Mechel, F. P.

    1998-10-01

    It has been suggested to describe the sound field in a wedge-shaped duct in a cylindrical co-ordinate system in which the boundaries of the wedge lie in a co-ordinate surface. This suggestion was developed in a companion paper [1]. The wave equation can be separated only if the boundaries are ideally reflecting (rigid or soft). Two solutions were proposed in reference [1] for absorbing boundaries. In the first solution the sound field is composed of “ideal modes” (modes in a wedge with ideally reflecting boundaries); the boundary condition at the absorbing boundary then leads to a system of equations for the mode amplitudes. The problem with this method lies in the fact that there is no radial orthogonality of the ideal modes so that the precision of the field synthesis by ideal modes is doubtful. In the second method in reference [1] one defines “fictitious modes” which satisfy the boundary conditions at the flanks exactly and which are based on hypergeometric functions as radial functions, but which produce a “rest” in the wave equation. It was described how this rest can be minimized; this procedure leads to slow numerical integrations. In the present paper, the wedge is subdivided into duct sections with parallel walls (the boundary is stepped); the fields in the sections are composed of duct modes (modes in a straight lined duct); the mode amplitudes are determined from the boundary conditions at the section limits. The advantages of the present method are (analytically) the duct modes are orthogonal across the sections, so the mode amplitudes can be determined with the usual precision of a modal analysis, and (numerically) no numerical integrations are needed.

  17. Large scale test of wedge shaped micro strip gas counters

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Atz, S.; Aulchenko, V.; Bachmann, S.; Baiboussinov, B.; Barthe, S.; Beaumont, W.; Beckers, T.; Beissel, F.; Benhammou, Y.; Bergdolt, A.M.; Bernier, K.; Bluem, P.; Bondar, A.; Bouhali, O.; Boulogne, I.; Bozzo, M.; Brom, J.M.; Camps, C.; Chorowicz, V.; Coffin, J.; Commichau, V.; Contardo, D.; Croix, J.; Troy, J. de; Drouhin, F.; Eberle, H.; Fluegge, G.; Fontaine, J.-C.; Geist, W.; Goerlach, U.; Gundlfinger, K.; Hangarter, K.; Haroutunian, R.; Helleboid, J.M.; Henkes, Th.; Hoffer, M.; Hoffman, C.; Huss, D.; Ischebeck, R.; Jeanneau, F.; Juillot, P.; Junghans, S.; Kapp, M.R.; Kaercher, K.; Knoblauch, D.; Kraeber, M.; Krauth, M.; Kremp, J.; Lounis, A.; Luebelsmeyer, K.; Maazouzi, C.; Macke, D.; Metri, R.; Mirabito, L.; Mueller, Th.; Nagaslaev, V.; Neuberger, D.; Nowack, A.; Pallares, A.; Pandoulas, D.; Petertill, M.; Pooth, O.; Racca, C.; Ripp, I.; Ruoff, E.; Sauer, A.; Schmitz, P.; Schulte, R.; Schultz von Dratzig, A.; Schunk, J.P.; Schuster, G.; Schwaller, B.; Shektman, L.; Siedling, R.; Sigward, M.H.; Simonis, H.J.; Smadja, G.; Stefanescu, J.; Szczesny, H.; Tatarinov, A.; Thuemmel, W.H.; Tissot, S.; Titov, V.; Todorov, T.; Tonutti, M.; Udo, F.; Velde, C. Vander. E-mail: vandervelde@hep.iihe.ac.be; Doninck, W. van; Dyck, Ch. van; Vanlaer, P.; Lancker, L. van; Verdini, P.G.; Weseler, S.; Wittmer, B.; Wortmann, R.; Zghiche, A.; Zhukov, V

    1999-11-01

    In order to check the system aspects of the forward-backward MSGC tracker designed for the future CMS experiment at LHC, 38 trapezoidal MSGC counters assembled in six multi-substrates detector modules were built and exposed to a muon beam at the CERN SPS. Results on the gain uniformity along the wedge-shaped strip pattern and across the detector modules are shown together with measurements of the detection efficiency and the spatial resolution.

  18. Large scale test of wedge shaped micro strip gas counters

    CERN Document Server

    Ackermann, M; Aulchenko, V M; Bachmann, S; Baibusinov, B O; Barthe, S; Beaumont, W; Beckers, T; Beissel, F; Benhammou, Ya; Bergdolt, A M; Bernier, K; Blüm, H P; Bondar, A E; Bouhali, O; Boulogne, I; Bozzo, M; Brom, J M; Camps, C; Chorowicz, V; Coffin, J P; Commichau, V; Contardo, D; Croix, J; De Troy, J G; Drouhin, F; Eberle, H; Flügge, G; Fontaine, J C; Geist, Walter M; Goerlach, U; Gundlfinger, K; Hangarter, K; Haroutunian, R; Helleboid, J M; Henkes, T; Hoffer, M; Hoffmann, C; Huss, D; Ischebeck, R; Jeanneau, F; Juillot, P; Junghans, S; Kapp, M R; Kärcher, K; Knoblauch, D; Kräber, M H; Krauth, M; Kremp, J; Lounis, A; Lübelsmeyer, K; Maazouzi, C; Macke, D; Metri, R; Mirabito, L; Müller, T; Nagaslaev, V; Neuberger, D; Nowak, A; Pallarès, A; Pandoulas, D; Petertill, M; Pooth, O; Racca, C; Ripp, I; Ruoff, E; Sauer, A; Schmitz, P; Schulte, R; Schultz von Dratzig, A; Schunk, J P; Schuster, G; Schwaller, B; Shekhtman, L I; Siedling, R; Sigward, M H; Simonis, H J; Smadja, G; Stefanescu, J; Szczesny, H; Tatarinov, A A; Thümmel, W H; Tissot, S; Titov, V; Todorov, T; Tonutti, M; Udo, Fred; Van der Velde, C; Van Doninck, W K; Van Dyck, C; Vanlaer, P; Van Lancker, L; Verdini, P G; Weseler, S; Wittmer, B; Wortmann, R; Zghiche, A; Zhukov, V

    1999-01-01

    In order to check the system aspects of the forward-backward MSGC tracker designed for the future CMS experiment at LHC, 38 trapezoidal MSGC counters assembled in six multi-substrates detector modules were built and exposed to a muon beam at the CERN SPS. Results on the gain uniformity along the wedge-shaped strip pattern and across the detector modules are shown together with measurements of the detection efficiency and the spatial resolution. (8 refs).

  19. DNS of compressible turbulent boundary layer over a blunt wedge

    Institute of Scientific and Technical Information of China (English)

    LI Xinliang; FU Dexun; MA Yanwan

    2005-01-01

    Direct numerical simulation of spatially evolving compressible boundary layer over a blunt wedge is performed in this paper. The free-stream Mach number is 6 and the disturbance source produced by wall blowing and suction is located downstream of the sound-speed point. Statistics are studied and compared with the results in incompressible flat-plate boundary layer. The mean pressure gradient effects on the vortex structure are studied.

  20. Opening- and Closing-Wedge Distal Femoral Osteotomy

    Science.gov (United States)

    Chahla, Jorge; Mitchell, Justin J.; Liechti, Daniel J.; Moatshe, Gilbert; Menge, Travis J.; Dean, Chase S.; LaPrade, Robert F.

    2016-01-01

    Background: Lateral compartment osteoarthritis of the knee can be a challenging pathology in the younger, active population due to limited treatment options and high patient expectations. Distal femoral osteotomy (DFO) has been reported to be a potential treatment option. Purpose: To perform a systematic review on the survival, outcomes, and complications of DFO for treatment of genu valgum with concomitant lateral compartment osteoarthritis of the knee. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the literature was performed using the Cochrane Database of Systematic Reviews, the Cochrane Central Registry of Controlled Trials, PubMed, and MEDLINE from 1980 to present. Inclusion criteria were as follows: outcomes of opening- and closing-wedge DFOs performed for treatment of genu valgum with concomitant lateral compartment osteoarthritis of the knee, English language, minimum 2-year follow-up, and human studies. Data abstracted from the selected studies included type of osteotomy (opening vs closing), survival rate, patient-reported and radiographic outcomes, and complications. Results: Fourteen studies met the inclusion criteria and were considered for the review. A total of 9 closing-wedge and 5 opening-wedge DFO studies were included. All were retrospective studies and reported good to excellent patient-reported outcomes after DFO. Survival decreased with increasing time from surgery, with 1 study reporting a 100% survival rate at 6.5 years, compared with 21.5% at 20 years in another study. A low rate of complications was reported throughout the review. Conclusion: Highly heterogeneous literature exists for both opening- and closing-wedge DFOs for the treatment of isolated lateral compartment osteoarthritis with valgus malalignment. A mean survival rate of 80% at 10-year follow-up was reported, supporting that this procedure can be a viable treatment option to delay or reduce the need for joint arthroplasty. A low

  1. Wedge-local quantum fields on a nonconstant noncommutative spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Much, A. [Max-Planck-Institute for Mathematics in the Sciences, 04103 Leipzig (Germany) and Institute for Theoretical Physics, University of Leipzig, 04009 Leipzig (Germany)

    2012-08-15

    Within the framework of warped convolutions we deform the massless free scalar field. The deformation is performed by using the generators of the special conformal transformations. The investigation shows that the deformed field turns out to be wedge-local. Furthermore, it is shown that the spacetime induced by the deformation with the special conformal operators is nonconstant noncommutative. The noncommutativity is obtained by calculating the deformed commutator of the coordinates.

  2. On the acoustic wedge design and simulation of anechoic chamber

    Science.gov (United States)

    Jiang, Changyong; Zhang, Shangyu; Huang, Lixi

    2016-10-01

    This study proposes an alternative to the classic wedge design for anechoic chambers, which is the uniform-then-gradient, flat-wall (UGFW) structure. The working mechanisms of the proposed structure and the traditional wedge are analyzed. It is found that their absorption patterns are different. The parameters of both structures are optimized for achieving minimum absorber depth, under the condition of absorbing 99% of normal incident sound energy. It is found that, the UGFW structure achieves a smaller total depth for the cut-off frequencies ranging from 100 Hz to 250 Hz. This paper also proposes a modification for the complex source image (CSI) model for the empirical simulation of anechoic chambers, originally proposed by Bonfiglio et al. [J. Acoust. Soc. Am. 134 (1), 285-291 (2013)]. The modified CSI model considers the non-locally reactive effect of absorbers at oblique incidence, and the improvement is verified by a full, finite-element simulation of a small chamber. With the modified CSI model, the performance of both decorations with the optimized parameters in a large chamber is simulated. The simulation results are analyzed and checked against the tolerance of 1.5 dB deviation from the inverse square law, stipulated in the ISO standard 3745(2003). In terms of the total decoration depth and anechoic chamber performance, the UGFW structure is better than the classic wedge design.

  3. Wave dynamic processes in cellular detonation reflection from wedges

    Institute of Scientific and Technical Information of China (English)

    Zongmin Hu; Zonglin Jiang

    2007-01-01

    When the cell width of the incident deto-nation wave (IDW) is comparable to or larger than theMach stem height,self-similarity will fail during IDWreflection from a wedge surface.In this paper,the det-onation reflection from wedges is investigated for thewave dynamic processes occurring in the wave front,including transverse shock motion and detonation cellvariations behind the Mach stem.A detailed reactionmodel is implemented to simulate two-dimensional cel-lular detonations in stoichiometric mixtures of H2/O2diluted by Argon.The numerical results show that thetransverse waves,which cross the triple point trajec-tory of Mach reflection,travel along the Mach stem andreflect back from the wedge surface,control the size ofthe cells in the region swept by the Mach stem.It is theenergy carried by these transverse waves that sustainsthe triple-wave-collision with a higher frequency withinthe over-driven Mach stem.In some cases,local wavedynamic processes and wave structures play a dominantrole in determining the pattern of cellular record,lead-ing to the fact that the cellular patterns after the Machstem exhibit some peculiar modes.

  4. Deformation transients in the brittle regime: Insights from spring-wedge experiments

    Science.gov (United States)

    Rosenau, Matthias; Santimano, Tasca; Oncken, Onno

    2016-04-01

    Deformation of the earth's crust varies over timescales ranging from the seismic cycle to plate tectonic phases. Seismic cycles can generically be explained by sudden coseismic release of strain energy accumulated slowly over the interseismic period. The simplest models of such transient behavior is a spring-slider system where the spring stores elastic energy and the slider is characterized by static and dynamic friction at its base allowing cyclic occurrence of slip instabilities. Here we extend this model by allowing the slider to deform in an accretionary wedge type system. Because cyclic thrust formation is associated with bulk strain weakening this should introduce slip instabilities at the time-scale of accretionary cycles superimposed on seismic cycles which are controlled by static and dynamic friction at the wedge base. To test this hypothesis we set up sandbox-type experiments where the backwall is not rigid but elastic. We vary stiffness, friction coefficients and amount of strain weakening during fault formation and reactivation within realistic ranges when scaled to nature and monitor backwall push force and surface deformation at high resolution. We observe slip instabilities both at seismic and accretionary cycle scale. Depending on the ratio of the amount of strain weakening to elastic stiffness, shortening rate increases transiently by a factor of 2-3 during fault growth. Applied to nature our observation suggests that episodic deformation transients might be interpreted as longterm slip instabilities related to crustal weakening at all relevant spatial scales: At local scale "slow earthquakes" might be interpreted as the result of the interplay between matrix stiffness and strain weakening in fault gouge material. At regional scale, applying buckling theory, we predict that deformation zones bordered by "soft" oceanic plates (e.g. the Andes) are more susceptible to deformation transients than "stiff" intracontinental settings (e.g. the Himalaya).

  5. Irregular Characteristics of Bond Interface Formation in Ultrasonic Wire Wedge Bonding

    Institute of Scientific and Technical Information of China (English)

    Mingyu LI; Hongjun JI; Chunqing WANG; Au Tai KUNG; Han Sur BANG; Hee Seon BANG

    2006-01-01

    The mechanism of ultrasonic wire wedge bonding, one of the die/chip interconnection methods, was investigated based on the characteristics of the ultrasonic wire bonding joints. The Al-1%Si wire of 25 μm in diameter was bonded on Au/Ni/Cu pad and the joint cross-section was analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results indicated that it is irregular for the ultrasonic bond formation, non-welded at the centre but joining well at the periphery, especially at the heel and toe of the joint. Furthermore, the diffusion and/or reaction at the cross-section interface are not clear at C-zone, while there exists a strip layer microstructure at P-zone, and the composition is 78.96 at. pct Al and 14.88 at. pct Ni, close to the Al3Ni intermetallic compound. All these observations are tentatively ascribed to the plastic flow enhanced by ultrasonic vibration and repeated cold deformation driving interdiffusion between Al and Ni at bond interface.

  6. Robustness of oscillatory α2 dynamos in spherical wedges

    Science.gov (United States)

    Cole, E.; Brandenburg, A.; Käpylä, P. J.; Käpylä, M. J.

    2016-10-01

    Context. Large-scale dynamo simulations are sometimes confined to spherical wedge geometries by imposing artificial boundary conditions at high latitudes. This may lead to spatio-temporal behaviours that are not representative of those in full spherical shells. Aims: We study the connection between spherical wedge and full spherical shell geometries using simple mean-field dynamos. Methods: We solve the equations for one-dimensional time-dependent α2 and α2Ω mean-field dynamos with only latitudinal extent to examine the effects of varying the polar angle θ0 between the latitudinal boundaries and the poles in spherical coordinates. Results: In the case of constant α and ηt profiles, we find oscillatory solutions only with the commonly used perfect conductor boundary condition in a wedge geometry, while for full spheres all boundary conditions produce stationary solutions, indicating that perfect conductor conditions lead to unphysical solutions in such a wedge setup. To search for configurations in which this problem can be alleviated we choose a profile of the turbulent magnetic diffusivity that decreases toward the poles, corresponding to high conductivity there. Oscillatory solutions are now achieved with models extending to the poles, but the magnetic field is strongly concentrated near the poles and the oscillation period is very long. By changing both the turbulent magnetic diffusivity and α profiles so that both effects are more concentrated toward the equator, we see oscillatory dynamos with equatorward drift, shorter cycles, and magnetic fields distributed over a wider range of latitudes. Those profiles thus remove the sensitive and unphysical dependence on θ0. When introducing radial shear, we again see oscillatory dynamos, and the direction of drift follows the Parker-Yoshimura rule. Conclusions: A reduced α effect near the poles with a turbulent diffusivity concentrated toward the equator yields oscillatory dynamos with equatorward migration and

  7. Chronology and palaeoenvironmental implications of the ice-wedge pseudomorphs and composite-wedge casts on the Magdalen Islands (eastern Canada)

    DEFF Research Database (Denmark)

    Remillard, A.M.; Hetu, B.; Bernatchez, P.

    2015-01-01

    The Magdalen Islands are a valuable terrestrial record, evidencing the complex glacial and periglacial history of the Gulf of St. Lawrence. Thirteen structures interpreted as ice-wedge pseudomorphs or composite-wedge casts were observed at four sites on the southern Magdalen Islands and testify...

  8. A geophysical potential field study to image the Makran subduction zone in SE of Iran

    Science.gov (United States)

    Abedi, Maysam; Bahroudi, Abbas

    2016-10-01

    The Makran subduction wedge as one of the largest subduction complexes has been forming due to the Arabian oceanic lithosphere subducting beneath the Lut and the Afghan rigid block microplates. To better visualize the subducting oceanic crust in this region, a geophysical model of magnetic susceptibility from an airborne magnetic survey (line spacing about 7.5 km) over the Makran zone located at southeast of Iran is created to image various structural units in Iran plate. The constructed geophysical model from the 3D inverse modeling of the airborne magnetic data indicates a thin subducting slab to the north of the Makran structural zone. It is demonstrated that the thickness of sedimentary units varies approximately at an interval of 7.5-11 km from north to south of this zone in the Iranian plate, meanwhile the curie depth is also estimated approximately < 26 km. It is also shown the Jazmurian depression zone adjacent to the north of the Makran indicates high intensity magnetic anomalies due to being underlain by an ophiolite oceanic basement, while such intensity reduces over the Makran. The directional derivatives of the magnetic field data have subtle changes in the Makran, but strongly increase in the Jazmurian by enhancing and separating different structural boundaries in this region. In addition, the density variations of the subsurface geological layers were determined by 3D inversion of the ground-based gravity data over the whole study area, where the constructed density model was in good agreement with the magnetic one. According to the outputs of the magnetic susceptibility and the density contrast, the Arabian plate subducts to the north under the Eurasia with a very low dip angle in the Makran structural zone.

  9. Assessment of computerized treatment planning system accuracy in calculating wedge factors of physical wedged fields for 6 MV photon beams.

    Science.gov (United States)

    Muhammad, Wazir; Maqbool, Muhammad; Shahid, Muhammad; Hussain, Amjad; Tahir, Sajjad; Matiullah; Rooh, Gul; Ahmad, Tanveer; Lee, Sang Hoon

    2011-07-01

    Wedge filters are commonly used in external beam radiotherapy to achieve a uniform dose distribution within the target volume. The main objective of this study was to investigate the accuracy of the beam modifier algorithm of Theraplan plus (TPP version 3.8) treatment planning system and to confirm that either the beam hardening, beam softening and attenuation coefficients along with wedge geometry and measured wedge factor at single depth and multiple fields sizes can be the replacement of wedged profile and wedged cross-sectional data or not. In this regard the effect of beam hardening and beam softening was studied with physical wedges for 6 MV photons. The Normalized Wedge Factors (NWFs) were measured experimentally as well as calculated with the Theraplan plus, as a function of depth and field size in a water phantom for 15°, 30°, 45°, and 60° wedge filters. The beam hardening and softening was determined experimentally by deriving the required coefficients for all wedge angles. The TPP version 3.8 requires wedge transmission factor at single depth and multiple field sizes. Without incorporating the hardening and softening coefficients the percent difference between measured and calculated NFWs was as high as 7%. After the introduction of these parameters into the algorithm, the agreement between measured and TPP (V 3.8) calculated NWFs were improved to within 2 percent for various depths. Similar improvement was observed in TPP version 3.8 while calculating NWFs for various field sizes when the required coefficients were adjusted. In conclusion, the dose calculation algorithm of TPP version 3.8 showed good accuracy for a 6 MV photon beam provided beam hardening and softening parameters are taken into account. From the results, it is also concluded that, the beam hardening, beam softening and attenuation coefficients along with wedge geometry and measured wedge factor at single depth and multiple fields sizes can be the replacement of wedged profile and

  10. Climate stabilization wedges in action: a systems approach to energy sustainability for Hawaii Island.

    Science.gov (United States)

    Johnson, Jeremiah; Chertow, Marian

    2009-04-01

    Pacala and Socolow developed a framework to stabilize global greenhouse gas levels for the next fifty years using wedges of constant size representing an increasing use of existing technologies and approaches for energy efficiency, carbon free generation, renewables, and carbon storage. The research presented here applies their approach to Hawaii Island, with modifications to support local scale analysis and employing a "bottom-up" methodology that allows for wedges of various sizes. A discretely bounded spatial unit offers a testing ground for a holistic approach to improving the energy sector with the identification of local options and limitations to the implementation of a comprehensive energy strategy. Nearly 80% of total primary energy demand across all sectors for Hawaii Island is currently met using petroleum-based fuels.The Sustainable Energy Plan scenario included here presents an internally consistent set of recommendations bounded by local constraints in areas such as transportation efficiency, centralized renewable generation (e.g., geothermal, wind), reduction in transmission losses, and improved building efficiency. This scenario shows thatthe demand for primary energy in 2030 could be reduced by 23% through efficiency measures while 46% could be met by renewable generation, resulting in only 31% of the projected demand being met by fossil fuels. In 2030, the annual releases of greenhouse gases would be 3.2 Mt CO2-eq/year under the Baseline scenario, while the Sustainable Energy Plan would reduce this to 1.2 Mt CO2-eq/year--an annual emissions rate 40% below 2006 levels and 10% below 1990 levels. The total for greenhouse gas emissions during the 24-year study period (2007 to 2030) is 59.9 Mt CO2-eq under the Baseline scenario and 32.5 Mt CO2-eq under the Sustainable Energy Plan scenario. Numerous combinations of efficiency and renewable energy options can be employed in a manner that stabilizes the greenhouse gas emissions of Hawaii Island.

  11. Observation of wedge waves and their mode transformation by laser ultrasonic technique

    Institute of Scientific and Technical Information of China (English)

    Jing Jia; Zhonghua Shen; Lijuan Wang; Ling Yuan

    2011-01-01

    Wedge waves (WWs) in wedges, including their dispersion characteristics and mode transformation, are investigated using the laser ultrasound technique. Pulsed laser excitation and optical deflection beam method for detection are used to record WWs. Numerous WWs are detected by scanning the excitation laser along the wedge tip. Dispersions of WWs are obtained by using the two-dimensional (2D) Fourier transformation method, and different WW orders are revealed on the wedges. Mode transformation is determined by fixing the distance between the excitation and detection position, as well as by scanning the samples along the normal direction of the wedge tip.%@@ Wedge waves (WWs) in wedges, including their dispersion characteristics and mode transformation, are investigated using the laser ultrasound technique. Pulsed laser excitation and optical deflection beam method for detection are used to record WWs. Numerous WWs are detected by scanning the excitation laser along the wedge tip. Dispersions of WWs are obtained by using the two-dimensional (2D) Fourier transformation method, and different WW orders are revealed on the wedges. Mode transformation is determined by fixing the distance between the excitation and detection position, as well as by scanning the samples along the normal direction of the wedge tip.

  12. Burial and exhumation in a subduction wedge: Mutual constraints from thermomechanical modeling and natural P-T-t data (Schistes Lustrés, western Alps)

    Science.gov (United States)

    Yamato, P.; Agard, P.; Burov, E.; Le Pourhiet, L.; Jolivet, L.; Tiberi, C.

    2007-07-01

    The dynamic processes leading to synconvergent exhumation of high-pressure low-temperature (HP-LT) rocks at oceanic accretionary margins, as well as the mechanisms maintaining nearly steady state regime in most accretion prisms, remain poorly understood. The present study aims at getting better constraints on the rheology, thermal conductivity, and chemical properties of the sediments in subduction zones. To reach that goal, oceanic subduction is modeled using a forward visco-elasto-plastic thermomechanical code (PARA(O)VOZ-FLAC algorithm), and synthetic pressure-temperature-time (P-T-t) paths, predicted from numerical experiments, are compared with natural P-T-t paths. The study is focused on the well constrained Schistes Lustrés complex (SL: western Alps) which is thought to represent the fossil accretionary wedge of the Liguro-Piemontese Ocean. For convergence rates comparable to Alpine subduction rates (˜3 cm yr-1), the best-fitting results are obtained for high-viscosity, low-density wedge sediments and/or a strong lower continental crust. After a transition period of 3-5 Ma the modeled accretionary wedges reach a steady state which lasts over 20 Ma. Over that time span a significant proportion (˜35%) of sediments entering the wedge undergoes P-T conditions typical of the SL complex (˜15-20 kbar; 350-450°C) with similar P-T loops. Computed exhumation rates (<6 mm yr-1) are in agreement with observations (1-5 mm yr-1). In presence of a serpentinite layer below the oceanic crust, exhumation of oceanic material takes place at rates approaching 3 mm yr-1. In all experiments the total pressure in the accretionary wedge never deviated by more than ±10% from the lithostatic component.

  13. Kinematic evolution of a tectonic wedge above a flat-lying décollement: The Alpine foreland at the interface between the Jura Mountains (Northern Alps) and the Upper Rhine graben

    Science.gov (United States)

    Nivière, Bertrand; Giamboni, Marzio; Innocent, Christophe; Winter, Thierry

    2006-06-01

    We estimate strain rates of three parameters that describe the buildup of a tectonic wedge (Jura front, France). The uplift rate on frontal ramps decreases with the slip on the ramps and the coeval increase of vertical loads. The migration rate of the tip of the sole thrust appears to be episodic and faster than the translation rate of the backstop. The long-term tilting rate appears to be constant, whereas the short-term rate is slightly slower. We propose a model of wedge growth that proceeds without underthrusting. In a prefractured medium, the wedge would activate the frontal ramp with a weaker frictional resistance than the forward décollement. An instantaneous forward jump of the deformation front would occur when the resistance on the ramp equals the resistance of the frontal décollement. This model differs from those proposed for accretionary zones, and relates to the backstop of a single tapered orogenic belt.

  14. Deformation in the mantle wedge associated with Laramide flat-slab subduction

    Science.gov (United States)

    Behr, Whitney M.; Smith, Douglas

    2016-07-01

    Laramide crustal deformation in the Rocky Mountains of the west-central United States is often considered to relate to a narrow segment of shallow subduction of the Farallon slab, but there is no consensus as to how deformation along the slab-mantle lithosphere interface was accommodated. Here we investigate deformation in mantle rocks associated with hydration and shear above the flat-slab at its contact with the base of the North American plate. The rocks we focus on are deformed, hydrated, ultramafic inclusions hosted within diatremes of the Navajo Volcanic Field in the central Colorado Plateau that erupted during the waning stages of the Laramide orogeny. We document a range of deformation textures, including granular peridotites, porphyroclastic peridotites, mylonites, and cataclasites, which we interpret to reflect different proximities to a slab-mantle-interface shear zone. Mineral assemblages and chemistries constrain deformation to hydrous conditions in the temperature range ˜550-750°C. Despite the presence of hydrous phyllosilicates in modal percentages of up to 30%, deformation was dominated by dislocation creep in olivine. The mylonites exhibit an uncommon lattice preferred orientation (LPO) in olivine, known as B-type LPO in which the a-axes are aligned perpendicular to the flow direction. The low temperature, hydrated setting in which these fabrics formed is consistent with laboratory experiments that indicate B-type LPOs form under conditions of high stress and high water contents; furthermore, the mantle wedge context of these LPOs is consistent with observations of trench-parallel anisotropy in the mantle wedge above many modern subduction zones. Differential stress magnitudes in the mylonitic rocks estimated using paleopiezometry range from 290 to 444 MPa, and calculated effective viscosities using a wet olivine flow law are on the order of 1019-1023 Pa s. The high stress magnitudes, high effective viscosities, and high strains recorded in these

  15. Heat conduction problem of an evaporating liquid wedge

    Directory of Open Access Journals (Sweden)

    Tomas Barta

    2015-02-01

    Full Text Available We consider the stationary heat transfer near the contact line of an evaporating liquid wedge surrounded by the atmosphere of its pure vapor. In a simplified setting, the problem reduces to the Laplace equation in a half circle, subject to a non-homogeneous and singular boundary condition. By classical tools (conformal mapping, Green's function, we reformulate the problem as an integral equation for the unknown Neumann boundary condition in the setting of appropriate fractional Sobolev and weighted space. The unique solvability is then obtained by means of the Fredholm theorem.

  16. Interpretation and inverse analysis of the wedge splitting test

    DEFF Research Database (Denmark)

    Østergaard, Lennart; Stang, Henrik

    2002-01-01

    Determination of the stress-crack opening relationship, s(w) a material parameter in the fictitious crack model by Hillerborg has proven to be problematic and is still not a simple task to perform. However, this paper demonstrates that the cracked non-linear hinge model by Olesen may be applied...... to the wedge splitting test and that it is well suited for the interpretation of test results in terms of s(w). A fine agreement between the hinge and FEM-models has been found. It has also been found that the test and the hinge model form a solid basis for inverse analysis. The paper also discusses possible...

  17. Inverse analysis of the wedge-splitting test

    DEFF Research Database (Denmark)

    Skocek, Jan; Stang, Henrik

    2008-01-01

    The amount of information which it is possible to retrieve from the wedge-splitting test is investigated. Inverse analysis is undertaken based on the analytical hinge model for various multi-linear softening curves. This showed that the commonly used bi-linear softening curve can be replaced...... by an tip to quad-linear curve, which is reflected by increased accuracy of the test simulation. Furthermore it was demonstrated that the next refinement of the softening curve leads to convergence problems due to problems with local minima. Finally, the semi-analytically obtained results are verified using...

  18. Electric monopoles in generalised B\\wedge F theories

    CERN Document Server

    Temple-Raston, M

    1996-01-01

    A tensor product generalisation of B\\wedge F theories is proposed to give a Bogomol'nyi structure. Non-singular, stable, finite-energy particle-like solutions to the Bogomol'nyi equations are studied. Unlike Yang-Mills(-Higgs) theory, the Bogomol'nyi structure does not appear as a perfect square in the Lagrangian. Consequently, the Bogomol'nyi energy can be obtained in more than one way. The added flexibility permits electric monopole solutions to the field equations.

  19. Thrust fault segmentation and downward fault propagation in accretionary wedges: New Insights from 3D seismic reflection data

    Science.gov (United States)

    Orme, Haydn; Bell, Rebecca; Jackson, Christopher

    2016-04-01

    The shallow parts of subduction megathrust faults are typically thought to be aseismic and incapable of propagating seismic rupture. The 2011 Tohoku-Oki earthquake, however, ruptured all the way to the trench, proving that in some locations rupture can propagate through the accretionary wedge. An improved understanding of the structural character and physical properties of accretionary wedges is therefore crucial to begin to assess why such anomalously shallow seismic rupture occurs. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust network development in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images of entire networks. Thus our current understanding is largely underpinned by observations from analogue and numerical modelling, with limited observational data from natural examples. In this contribution we use PSDM, 3D seismic reflection data from the Nankai margin (3D Muroto dataset, available from the UTIG Academic Seismic Portal, Marine Geoscience Data System) to examine how imbricate thrust fault networks evolve during accretionary wedge growth. We unravel the evolution of faults within the protothrust and imbricate thrust zones by interpreting multiple horizons across faults and measuring fault displacement and fold amplitude along-strike; by doing this, we are able to investigate the three dimensional accrual of strain. We document a number of local displacement minima along-strike of faults, suggesting that, the protothrust and imbricate thrusts developed from the linkage of smaller, previously isolated fault segments. Although we often assume imbricate faults are likely to have propagated upwards from the décollement we show strong evidence for fault nucleation at shallow depths and downward propagation to intersect the décollement. The complex fault interactions documented here have implications for hydraulic compartmentalisation and pore

  20. The impact of slab dip variations, gaps and rollback on mantle wedge flow: insights from fluids experiments

    Science.gov (United States)

    MacDougall, Julia G.; Kincaid, Chris; Szwaja, Sara; Fischer, Karen M.

    2014-05-01

    Observed seismic anisotropy and geochemical anomalies indicate the presence of 3-D flow around and above subducting slabs. To investigate how slab geometry and velocity affect mantle flow, we conducted a set of experiments using a subduction apparatus in a fluid-filled tank. Our models comprise two independently adjustable, continuous belts to represent discrete sections of subducting slabs that kinematically drive flow in the surrounding glucose syrup that represents the upper mantle. We analyse how slab dip (ranging from 30° to 80°), slab dip difference between slab segments (ranging from 20° to 50°), rates of subduction (4-8 cm yr-1) and slab/trench rollback (0-3 cm yr-1) affect mantle flow. Whiskers were used to approximate mineral alignment induced by the flow, as well as to predict directions of seismic anisotropy. We find that dip variations between slab segments generate 3-D flow in the mantle wedge, where the path lines of trenchward moving mantle material above the slab are deflected towards the slab segment with the shallower dip. The degree of path line deflection increases as the difference in slab dip between the segments increases, and, for a fixed dip difference, as slab dip decreases. In cases of slab rollback and large slab dip differences, we observe intrusion of subslab material through the gap and into the wedge. Flow through the gap remains largely horizontal before eventual downward entrainment. Whisker alignment in the wedge flow is largely trench-normal, except near the lateral edges of the slab where toroidal flow dominates. In addition, whisker azimuths located above the slab gap deviate most strongly from trench-normal orientations when slab rollback does not occur. Such flow field complexities are likely sufficient to affect deep melt production and shallow melt delivery. However, none of the experiments produced flow fields that explain the trench-parallel shear wave splitting fast directions observed over broad arc and backarc

  1. The effect of shoe design and lateral wedging on knee loading

    DEFF Research Database (Denmark)

    Mølgaard, Carsten; Kersting, Uwe G.

    -dimensional gait analysis. Barefoot walking, walking in a running shoe, an Oxford-type leather shoe, and a rocker shoe were analyzed. The shoes were tested both with and without a 10-degree full length laterally wedged insole. Results: Similar, significant reductions in the peak knee adduction moment with lateral...... wedges were observed in all three types of shoes. However, differences between shoe design were of similar magnitude as the effect of laterally wedged insoles. Only marginal changes in muscle activity for lateral hamstrings during barefoot toe-out walking and gastrocnemius when using the Oxford wedged...

  2. Modified retro-tubercle opening-wedge versus conventional high tibial osteotomy.

    Science.gov (United States)

    Keyhani, Sohrab; Abbasian, Mohammad Reza; Kazemi, Seyed Morteza; Esmailiejah, Ali Akbar; Seyed Hosseinzadeh, Hamid Reza; Shahi, Alisina; Shahi, Ali Sina; Firouzi, Farzad

    2011-01-01

    Despite the fact that common surgical techniques for the treatment of genu varum usually correct the malalignment in the affected knee, these methods have significant complications and cause problems in the long term. Retro-tubercle opening-wedge high tibial osteotomy is among the newer techniques for the treatment of genu varum. The goal of this study was to compare the results of retro-tubercle opening-wedge high tibial osteotomy with those of medial opening-wedge osteotomy. In a randomized, controlled trial, 72 patients with varus knees who were scheduled for surgery were assigned into either the retro-tubercle opening-wedge high tibial osteotomy (n=34) or medial opening-wedge osteotomy groups (n=38). Groups were matched for age and sex. The position of the patella was compared with respect to the tuberosity and the upper tibial slope pre- and postoperatively. Patients were followed for an average of 13 months (range, 10-21 months). In the retro-tubercle opening-wedge high tibial osteotomy group, the length of the patellar tendon did not significantly differ pre- and postoperatively (P≥.5); however, in the medial opening-wedge osteotomy group, a statistically significant shortening was noted in patellar tendon postoperatively (P≤.05). Similarly, the tibial plateau inclination showed a statistically significant difference postoperatively in the medial opening-wedge osteotomy group, while the difference in the retro-tubercle opening-wedge high tibial osteotomy group did not reach statistical significance.

  3. Triangular metal wedges for subwavelength plasmon-polariton guiding at telecom wavelengths

    DEFF Research Database (Denmark)

    Boltasseva, Alexandra; Volkov, V.S.; Nielsen, Rasmus Bundgaard

    2008-01-01

    . Using scanning near-field optical imaging at the wavelengths in the range of 1.43 - 1.52 µm, we demonstrate low-loss (propagation length ~ 120 µm) and well-confined (mode width ≅ 1.3 µm) wedge plasmon-polariton guiding along triangular 6-µm-high and 70.5°- angle gold wedges. Experimental observations......We report on subwavelength plasmon-polariton guiding by triangular metal wedges at telecom wavelengths. A high-quality fabrication procedure for making gold wedge waveguides, which is also mass- production compatible offering large-scale parallel fabrication of plasmonic components, is developed...

  4. Final « pop-up » structural reactivation of the internal part of an orogenic wedge: west-central Pyrenees

    Science.gov (United States)

    Meresse, F.; Jolivet, M.; Labaume, P.; Teixell, A.

    2009-04-01

    Université Montpellier 2, INSU-CNRS, Laboratoire Géosciences Montpellier, cc060, 34095 Montpellier Cedex 5, France florian.meresse@gm.univ-montp2.fr Tectonics-sedimentation relationships are often used to describe the tectonic evolution of orogenic wedges. However, does the sedimentary record associated to the build-up of the wedge recall the entire tectonic history? Numerous studies based on tectono-stratigraphic and thermochronological data, as well as numerical modeling, have demonstrated that on the large scale the growth of the Pyrenees is characterized by a southward propagation of the deformation (e.g., Muñoz, 1992; Morris et al., 1998; Fitzgerald et al., 1999; Beaumont et al., 2000). However, in the west-central Pyrenees, recent thermochronological data have suggested that the in-sequence propagation of the basement thrust system was followed by out-of-sequence (re)activation of hinterland structures after the South-Pyrenean Frontal Thrust had been sealed (Jolivet et al., 2007). To better describe the structural evolution of the Pyrenean prism, we focused our work on a NNE-SSW transect from the northern piedmont (Bagnères-de-Bigorre), through the Axial Zone and down to the Jaca basin where tectonics-sedimentation relationships have been extensively described (e.g., Teixell, 1996). A crustal scale cross-section combined with detailed apatite fission track analysis are used as a case study to unravel in detail the deformation history. Apatite fission track data from the Bagnères-de-Bigorre Paleozoic massif (central ages: 41-42 Ma) and the Lesponne Hercynian granite (central age: 31 Ma) located in the North-Pyrenean Zone and in the north of the Axial Zone, respectively, reveal Middle Eocene-Early Oligocene denudation ages of the northern part of the wedge. Immediately to the south, central ages around 24-20 Ma attest to a Latest Oligocene-Early Miocene denudation ages of the Chiroulet granite. According to the structural context, these results suggest a

  5. Dying Flow Bursts as Generators of the Substorm Current Wedge

    Science.gov (United States)

    Haerendel, Gerhard

    2016-07-01

    Many theories or conjectures exist on the driver of the substorm current wedge, e.g. rerouting of the tail current, current disruption, flow braking, vortex formation, and current sheet collapse. Magnitude, spatial scale, and temporal development of the related magnetic perturbations suggest that the generator is related to the interaction of the flow bursts with the dipolar magnetosphere after onset of reconnection in the near-Earth tail. The question remains whether it is the flow energy that feeds the wedge current or the internal energy of the arriving plasma. In this presentation I argue for the latter. The current generation is attributed to the force exerted by the dipolarized magnetic field of the flow bursts on the preceding layer of high-beta plasma after flow braking. The generator current is the grad-B current at the outer boundary of the compressed high-beta plasma layers. It needs the sequential arrival of several flow bursts to account for duration and magnitude of the ionospheric closure current.

  6. Growth and mixing dynamics of mantle wedge plumes

    Science.gov (United States)

    Gorczyk, Weronika; Gerya, Taras V.; Connolly, James A. D.; Yuen, David A.

    2007-07-01

    Recent work suggests that hydrated partially molten thermal-chemical plumes that originate from subducted slab as a consequence of Rayleigh-Taylor instability are responsible for the heterogeneous composition of the mantle wedge. We use a two-dimensional ultrahigh-resolution numerical simulation involving 10 × 109 active markers to anticipate the detailed evolution of the internal structure of natural plumes beneath volcanic arcs in intraoceanic subduction settings. The plumes consist of partially molten hydrated peridotite, dry solid mantle, and subducted oceanic crust, which may compose as much as 12% of the plume. As plumes grow and mature these materials mix chaotically, resulting in attenuation and duplication of the original layering on scales of 1-1000 m. Comparison of numerical results with geological observations from the Horoman ultramafic complex in Japan suggests that mixing and differentiation processes related to development of partially molten plumes above slabs may be responsible for the strongly layered lithologically mixed (marble cake) structure of asthenospheric mantle wedges.

  7. Relation of the auroral substorm to the substorm current wedge

    Science.gov (United States)

    McPherron, Robert L.; Chu, Xiangning

    2016-12-01

    The auroral substorm is an organized sequence of events seen in the aurora near midnight. It is a manifestation of the magnetospheric substorm which is a disturbance of the magnetosphere brought about by the solar wind transfer of magnetic flux from the dayside to the tail lobes and its return through the plasma sheet to the dayside. The most dramatic feature of the auroral substorm is the sudden brightening and poleward expansion of the aurora. Intimately associated with this expansion is a westward electrical current flowing across the bulge of expanding aurora. This current is fed by a downward field-aligned current (FAC) at its eastern edge and an upward current at its western edge. This current system is called the substorm current wedge (SCW). The SCW forms within a minute of auroral expansion. FAC are created by pressure gradients and field line bending from shears in plasma flow. Both of these are the result of pileup and diversion of plasma flows in the near-earth plasma sheet. The origins of these flows are reconnection sites further back in the tail. The auroral expansion can be explained by a combination of a change in field line mapping caused by the substorm current wedge and a tailward growth of the outer edge of the pileup region. We illustrate this scenario with a complex substorm and discuss some of the problems associated with this interpretation.

  8. An automated optical wedge calibrator for Dobson ozone spectrophotometers

    Science.gov (United States)

    Evans, R. D.; Komhyr, W. D.; Grass, R. D.

    1994-01-01

    The Dobson ozone spectrophotometer measures the difference of intensity between selected wavelengths in the ultraviolet. The method uses an optical attenuator (the 'Wedge') in this measurement. The knowledge of the relationship of the wedge position to the attenuation is critical to the correct calculation of ozone from the measurement. The procedure to determine this relationship is time-consuming, and requires a highly skilled person to perform it correctly. The relationship has been found to change with time. For reliable ozone values, the procedure should be done on a Dobson instrument at regular intervals. Due to the skill and time necessary to perform this procedure, many instruments have gone as long as 15 years between procedures. This article describes an apparatus that performs the procedure under computer control, and is adaptable to the majority of existing Dobson instruments. Part of the apparatus is usable for normal operation of the Dobson instrument, and would allow computer collection of the data and real-time ozone measurements.

  9. Grounded theory.

    Science.gov (United States)

    Harris, Tina

    2015-04-29

    Grounded theory is a popular research approach in health care and the social sciences. This article provides a description of grounded theory methodology and its key components, using examples from published studies to demonstrate practical application. It aims to demystify grounded theory for novice nurse researchers, by explaining what it is, when to use it, why they would want to use it and how to use it. It should enable nurse researchers to decide if grounded theory is an appropriate approach for their research, and to determine the quality of any grounded theory research they read.

  10. Late Jurassic blueschist facies pebbles from the Western Carpathian orogenic wedge and paleostructural implications for Western Tethys evolution

    Science.gov (United States)

    Dal Piaz, Giorgio V.; Martin, Silvana; Villa, Igor M.; Gosso, Guido; Marschalko, Robert

    1995-08-01

    In spite of the absence of ophiolitic slices at the surface, some traces of the lost Tethys ocean are recorded along the Pieniny Klippen Belt (PKB), a narrow décollement thrust system sutured at the transpressive boundary between the Outer and Inner Carpathians. The enigmatic precollisional evolution of Western Carpathians can be deciphered from some late Albian to Campanian flysch conglomerates which display chrome spinel grains, ophiolitic detritus and pebbles of blueschist facies tholeiitic metabasalts yielding a 40Ar/39Ar plateau age of 155.4+/-0.6 Ma. Other detrital components are represented by extrabasinal pebbles of limestones, arc volcanics, and igneous to metamorphic basement rocks from southern sources. Our results suggest a markedly northward extension of the sublongitudinal Triassic Vardar (Meliata) Ocean and its subduction since the late Middle Jurassic, supposedly balanced westward by coeval spreading in the Ligurian-Piedmont basin of the Apennine-Western Alpine Tethys. A lateral kinematic connection between these diachronous and roughly parallel Tethys branches was provided on the north by a left-lateral east-west trending shear zone running from the Swiss-Austrian Penninic domain to the Northern Carpathians. This reconstruction replaces the classic model of two paired North Penninic and South Penninic oceanic basins and eastern homologues with the Briançonnais-Hochstegen and Czorstin microcontinents in between. The Late Jurassic-Early Cretaceous evolution of the Carpathian active margin was characterized by subduction metamorphism and accretion of a wide orogenic wedge; in this time, the shallowing to deeply subsiding basins inferred from facies analyses on the sedimentary units of the PKB were likely floored by individual sections of the growing wedge. Later, some exhuming blueschist ophiolitic units of the wedge were uplifted to the surface and functioned in the Albian-Campanian as an ``exotic ridge'' supplying clasts to the forearc basin

  11. Evidence of Arc Magma Genesis in a Paleo-Mantle Wedge, the Higashi-Akaishi Peridotite, Japan

    Science.gov (United States)

    Till, C. B.; Guild, M. R.; Grove, T. L.; Carlson, R. W.

    2014-12-01

    Located in the Sanbagawa subduction-related high-pressure metamorphic belt in SW Japan on the island of Shikoku, the Higashi-akaishi peridotite body is composed of dunite, lherzolite and garnet clinopyroxenite, interfingered in one locality with quartz-rich eclogite. Previous work indicates the P-T history of the peridotite includes rapid prograde metamorphism with peak temperatures of 700-810°C and pressures of 2.9-3.8 GPa [1] at ~88-89 Ma followed by rapid exhumation at >2.5 cm/yr [2,3]. Major and trace element and isotopic data from samples within the Higashi-akaishi peridotite presented here and in another recent study [4] provide a record of subduction zone melting processes in a paleo-mantle wedge. Ultramafic samples range from 40-52 wt.% SiO2, 1-11 wt.% Al2O3 and 21-45 wt.% MgO with olivine and clinopyroxene Mg#'s as high as 0.93. The quartz-rich eclogite contains 62 wt.% SiO2, 6 wt.% MgO and 13 wt.% Al2O3 with trace element concentrations that are enriched relative to the ultramafic samples. 87Sr/86Sr (.703237-.704288), 143Nd/144Nd (ɛNd=+2 to +6) and Pb isotopic compositions are within the range of previously studied Japanese arc rocks. We interpret the pyroxenites as shallowly crystallized cumulates with varying amounts of trapped hydrous melt and the harzburgites as residues of melting. The peak P-T conditions of these rocks are similar to the solidus conditions of H2O-saturated fertile mantle near the base of the mantle wedge [5,6]. The presence of garnet porphyroblasts that enclose primary euhedral chlorite together with the chemical evidence, suggest these samples are associated with mantle melting in the presence of H2O. Major element modeling suggests the quartz-rich eclogite composition can be reproduced through mixing melts of subducted sediment with wet peridotite melts in the mantle wedge. Thus the Higashi-aikashi rock suite provides an in-situ record of the beginnings of hydrous melting and the mechanisms of metasomatism in the mantle wedge

  12. Duality in nonlinear B$\\wedge$F models equivalence between self-dual and topologically massive Born-Infeld B$\\wedge$F models

    CERN Document Server

    Menezes, R; Ribeiro, R F; Wotzasek, C

    2002-01-01

    We study the dual equivalence between the nonlinear generalization of the self-dual ($NSD_{B\\wedge F}$) and the topologically massive $B\\wedge F$ models with particular emphasis on the nonlinear electrodynamics proposed by Born and Infeld. This is done through a dynamical gauge embedding of the nonlinear self-dual model yielding to a gauge invariant and dynamically equivalent theory. We clearly show that nonpolinomial $NSD_{B\\wedge F}$ models can be mapped, through a properly defined duality transformation, into $TM_{B\\wedge F}$ actions. The general result obtained is then particularized for a number of examples, including the Born-Infeld-BF (BIBF) model that has experienced a revival in the recent literature.

  13. A two-dimensional model of the methane cycle in a sedimentary accretionary wedge

    Directory of Open Access Journals (Sweden)

    D. E. Archer

    2012-08-01

    Full Text Available A two-dimensional model of sediment column geophysics and geochemistry has been adapted to the problem of an accretionary wedge formation, patterned after the margin of the Juan de Fuca plate as it subducts under the North American plate. Much of the model description is given in a companion paper about the application of the model to an idealized passive margin setting; here we build on that formulation to simulate the impact of the sediment deformation, as it approaches the subduction zone, on the methane cycle. The active margin configuration of the model shares sensitivities with the passive margin configuration, in that sensitivities to organic carbon deposition and respiration kinetics, and to vertical bubble transport and redissolution in the sediment, are stronger than the sensitivity to ocean temperature. The active margin simulation shows a complex sensitivity of hydrate inventory to plate subduction velocity, with results depending strongly on the geothermal heat flux. In low heat-flux conditions, the model produces a larger inventory of hydrate per meter of coastline in the passive margin than active margin configurations. However, the local hydrate concentrations, as pore volume saturation, are higher in the active setting than in the passive, as generally observed in the field.

  14. Salt wedge determination using electrical sounding method in the region of Oued Nador (Tipaza, Algeria)

    Science.gov (United States)

    Amine Bechkit, Mohamed; Benaïssa, Zahia; Ouadfeul, Sid Ali; Deghmoum, Feriel

    2017-04-01

    The marine intrusion of freshwater aquifers by salt water results in soil degradation due to their salinization. The present survey aims to study the position of the fresh water - salt water interface using electric sounding method in the region of Oued Nador (Tipaza, Algeria). It is important to know the position of this interface for the continuation of the aquifer exploitation. For this, we conducted, in this zone, seven electric soundings oriented north-west south-east, with Schlumberger electrodes configuration. The inversion of the apparent resistivity data via the IP2Win software allowed us to recover the true values of electrical resistivity. The exploitation of obtained data requires the implementation of a geo-electric section, and for the interpretation, the results of a standard electrical sounding, acquired near the study area, are used. The results of this geophysical study allowed us to locate the freshwater - salt water contact with resistivity values that can reach 50 ohm m for freshwater formation, and less than 10 ohm m for saturated saltwater formation. The depth of the contact between fresh water and salt water increases gradually from 38 m to 40 m near the coast, and this over a distance of 0 m to 500 m, and then rises abruptly beyond a distance of 500 m at the borehole N°3 where it reaches the maximum depth of 97 m. Key words: Electrical survey - Salt wedge - Electrical resistivity - Aquifer - Intrusion.

  15. First direct dating of Late Pleistocene ice-wedges by AMS

    NARCIS (Netherlands)

    Vasil'chuk, YK; van der Plicht, J; Jungner, H; Sonninen, E; Vasil'chuk, AC; Vasil'chuk, Yurij K.; Vasil'chuk, Alla C.

    2000-01-01

    We present the first direct dating by C-14-accelerator mass spectrometry of three Late Pleistocene syngenetic ice-wedges from the Seyaha cross-section. They are representative of permafrost with multistage ice-wedges from the North of Western Siberia. The most important result is the clear vertical

  16. Revisit the classical Newmark displacement method for earthquake-induced wedge slide

    Science.gov (United States)

    Yang, Che-Ming; Cheng, Hui-Yun; Wu, Wen-Jie; Hsu, Chang-Hsuan; Dong, Jia-Jyun; Lee, Chyi-Tyi

    2016-04-01

    Newmark displacement method has been widely used to study the earthquake-induced landslides and adopted to explore the initiation and kinematics of catastrophic planar failure in recent years. However, surprisingly few researchers utilize the Newmark displacement method to study the earthquake-induced wedge slide. The classical Newmark displacement method for earthquake-induced wedge sliding assumed the wedge is rigid and the vertical acceleration, as well as the horizontal acceleration perpendicular to the sliding direction, is neglected. Moreover, the friction coefficients on the weak planes are assumed as unchanged during sliding. The purpose of this study is to test the reasonableness of the aforementioned assumptions. This study uses Newmark displacement method incorporating the rigid wedge method (RWM) and maximum shear stress method (MSSM) to evaluate the influence of wedge deformation. We design the geometry of the wedge and input the synthetic seismicity to trigger the wedge slide. The influence for neglecting the vertical and horizontal (perpendicular to the sliding direction) accelerations is also assessed. Besides, this research incorporates the velocity-displacement dependent friction law in the analysis to evaluate the influence of constant friction coefficient assumption. Result of this study illustrated that the aforementioned assumptions have significant effects on the calculated permeant displacement, moving speed, and failure initiation. To conclude, this study provides new insights on the initiation and kinematics of an earthquake induced wedge slide.

  17. Enhancement of linear and second-order hyperpolarizabilities in wedge-shaped nanostructures

    Science.gov (United States)

    Jayabalan, J.; Singh, Manoranjan P.; Rustagi, K. C.

    2003-08-01

    Analytical solutions for the wave functions for free electrons inside a wedge-shaped quantum dot are reported. For silver wedge-shaped quantum dots, linear and second-order hyperpolarizabilities are calculated for various apex angles. It is found that linear and nonlinear hyperpolarizabilities both increase with decreasing apex angle.

  18. Duwamish Waterways Navigation Improvement Study: Analysis of Impacts on Water Quality and Salt Wedge Characteristics.

    Science.gov (United States)

    1981-02-01

    dissolved oxygen consumption in the saltwater wedge is emphasized. A section has also been prepared discussing sediment transport in the estuary...biomass produced and sedimented 23 1,000 800 00 0 400 Xi. . *-*’* 200 ox- :~. ---0 - .....’ ~ ’J FIGURE 6 Annual Dissolved Oxygen Consumption in the wedge

  19. Reflection of a converging cylindrical shock wave segment by a straight wedge

    Science.gov (United States)

    Gray, B.; Skews, B.

    2017-01-01

    As a converging cylindrical shock wave propagates over a wedge, the shock wave accelerates and the angle between the shock wave and the wedge decreases. This causes the conditions at the reflection point to move from what would be the irregular reflection domain for a straight shock wave into the regular reflection domain. This paper covers a largely qualitative study of the reflection of converging shock wave segments with Mach numbers between 1.2 and 2.1 by wedges inclined at angles between 15° and 60° from experimental and numerical results. The sonic condition conventionally used for predicting the type of reflection of straight shock waves was found to also be suitable for predicting the initial reflection of a curved shock wave. Initially regular reflections persisted until the shock was completely reflected by the wedge, whereas the triple point of initially irregular reflections was observed to return to the wedge surface, forming transitioned regular reflection. After the incident shock wave was completely reflected by the wedge, a shock wave focusing mechanism was observed to amplify the pressure on the surface of the wedge by a factor of up to 100 for low wedge angles.

  20. A quantum hybrid with a thin antenna at the vertex of a wedge

    Science.gov (United States)

    Carlone, Raffaele; Posilicano, Andrea

    2017-03-01

    We study the spectrum, resonances and scattering matrix of a quantum Hamiltonian on a "hybrid surface" consisting of a half-line attached by its endpoint to the vertex of a concave planar wedge. At the boundary of the wedge, outside the vertex, homogeneous Dirichlet conditions are imposed. The system is tunable by varying the measure of the angle at the vertex.

  1. Comparison of dosimetric characteristics of Siemens virtual and physical wedges for ONCOR linear accelerator

    Directory of Open Access Journals (Sweden)

    Attalla Ehab

    2010-01-01

    Full Text Available Dosimetric properties of virtual wedge (VW and physical wedge (PW in 6- and 10-MV photon beams from a Siemens ONCOR linear accelerator, including wedge factors, depth doses, dose profiles, peripheral doses, are compared. While there is a great difference in absolute values of wedge factors, VW factors (VWFs and PW factors (PWFs have a similar trend as a function of field size. PWFs have stronger depth dependence than VWF due to beam hardening in PW fields. VW dose profiles in the wedge direction, in general, match very well with those of PW, except in the toe area of large wedge angles with large field sizes. Dose profiles in the nonwedge direction show a significant reduction in PW fields due to off-axis beam softening and oblique filtration. PW fields have significantly higher peripheral doses than open and VW fields. VW fields have similar surface doses as the open fields, while PW fields have lower surface doses. Surface doses for both VW and PW increase with field size and slightly with wedge angle. For VW fields with wedge angles 45° and less, the initial gap up to 3 cm is dosimetrically acceptable when compared to dose profiles of PW. VW fields in general use less monitor units than PW fields.

  2. Investigation of a Wedge Adhesion Test for Edge Seals

    Energy Technology Data Exchange (ETDEWEB)

    Kempe, Michael; Wohlgemuth, John; Miller, David; Postak, Lori; Booth, Dennis; Phillips, Nancy

    2016-09-26

    Many photovoltaic (PV) technologies have been found to be sensitive to moisture that diffuses into a PV package. Even with the use of impermeable frontsheets and backsheets, moisture can penetrate from the edges of a module. To limit this moisture ingress pathway from occurring, manufacturers often use a low permeability polyisobutylene (PIB) based edge seal filled with desiccant to further restrict moisture ingress. Moisture ingress studies have shown that these materials are capable of blocking moisture for the 25-year life of a module; but to do so, they must remain well-adhered and free of cracks. This work focuses on adapting the Boeing Wedge test for use with edge seals laminated using glass substrates as part of a strategy to assess the long-term durability of edge seals. The advantage of this method is that it duplicates the residual stresses and strains that a glass/glass module may have when the lamination process results in some residual glass bending that puts the perimeter in tension. Additionally, this method allows one to simultaneously expose the material to thermal stress, humidity, mechanical stress, and ultraviolet radiation. The disadvantage of this method generally is that we are limited by the fracture toughness of the glass substrates that the edge seal is adhered to. However, the low toughness of typical uncrosslinked or sparsely crosslinked PIB makes them suitable for this technique. We present data obtained during the development of the wedge test for use with PV edge seal materials. This includes development of the measuring techniques and evaluation of the test method with relevant materials. We find consistent data within a given experiment, along with the theoretical independence of fracture toughness measurements with wedge thickness. This indicates that the test methodology is reproducible. However, even though individual experimental sets are consistent, the reproducibility between experimental sets is poor. We believe this may be

  3. Investigation of a wedge adhesion test for edge seals

    Science.gov (United States)

    Kempe, Michael; Wohlgemuth, John; Miller, David; Postak, Lori; Booth, Dennis; Phillips, Nancy

    2016-09-01

    Many photovoltaic (PV) technologies have been found to be sensitive to moisture that diffuses into a PV package. Even with the use of impermeable frontsheets and backsheets, moisture can penetrate from the edges of a module. To limit this moisture ingress pathway from occurring, manufacturers often use a low permeability polyisobutylene (PIB) based edge seal filled with desiccant to further restrict moisture ingress. Moisture ingress studies have shown that these materials are capable of blocking moisture for the 25-year life of a module; but to do so, they must remain well-adhered and free of cracks. This work focuses on adapting the Boeing Wedge test for use with edge seals laminated using glass substrates as part of a strategy to assess the long-term durability of edge seals. The advantage of this method is that it duplicates the residual stresses and strains that a glass/glass module may have when the lamination process results in some residual glass bending that puts the perimeter in tension. Additionally, this method allows one to simultaneously expose the material to thermal stress, humidity, mechanical stress, and ultraviolet radiation. The disadvantage of this method generally is that we are limited by the fracture toughness of the glass substrates that the edge seal is adhered to. However, the low toughness of typical uncrosslinked or sparsely crosslinked PIB makes them suitable for this technique. We present data obtained during the development of the wedge test for use with PV edge seal materials. This includes development of the measuring techniques and evaluation of the test method with relevant materials. We find consistent data within a given experiment, along with the theoretical independence of fracture toughness measurements with wedge thickness. This indicates that the test methodology is reproducible. However, even though individual experimental sets are consistent, the reproducibility between experimental sets is poor. We believe this may be

  4. Structural and metamorphic evolution of serpentinites and rodingites recycled in the Alpine subduction wedge

    Science.gov (United States)

    Zanoni, D.; Rebay, G.; Spalla, M. I.

    2015-12-01

    Hydration-dehydration of mantle rocks affects the viscosity of the mantle wedge and plays a prominent role in subduction zone tectonics, facilitating marble cake-type instead of large-slice dynamics. An accurate structural and petrologic investigation of serpentinites from orogenic belts, supported by their long-lived structural memory, can help to recognize pressure-sensitive mineral assemblages for deciphering their P-prograde and -retrograde tectonic trajectories. The European Alps preserve large volumes of the hydrated upper part of the oceanic lithosphere that represents the main water carrier into the Alpine subduction zone. Therefore, it is important to understand what happens during subduction when these rocks reach P-T conditions proximal to those that trigger the break-down of serpentine, formed during oceanic metamorphism, to produce olivine and clinopyroxene. Rodingites associated with serpentinites are usually derived from metasomatic ocean floor processes but rodingitization can also happen in subduction environments. Multiscale structural and petrologic analyses of serpentinites and enclosed rodingites have been combined to define the HP mineral assemblages in the Zermatt-Saas ophiolites. They record 3 syn-metamorphic stages of ductile deformation during the Alpine cycle, following the ocean floor history that is testified by structural and metamorphic relics in both rock types. D1 and D2 developed under HP to UHP conditions and D3 under lower P conditions. Syn-D2 assemblages in serpentinites and rodingites indicate conditions of 2.5 ± 0.3 GPa and 600 ± 20°C. This interdisciplinary approach shows that the dominant structural and metamorphic imprint of the Zermatt-Saas eclogitized serpentinites and rodingites developed during the Alpine subduction and that subduction-related serpentinite de-hydration occurred exclusively at Pmax conditions, during D2 deformation. In contrast, in the favourable rodingite bulk composition (Ca-rich), hydrated minerals

  5. Aqueous fluids and sedimentary melts as agents for mantle wedge metasomatism, as inferred from peridotite xenoliths at Pinatubo and Iraya volcanoes, Luzon arc, Philippines

    Science.gov (United States)

    Yoshikawa, Masako; Tamura, Akihiro; Arai, Shoji; Kawamoto, Tatsuhiko; Payot, Betchaida D.; Rivera, Danikko John; Bariso, Ericson B.; Mirabueno, Ma. Hannah T.; Okuno, Mitsuru; Kobayashi, Tetsuo

    2016-10-01

    Mantle xenoliths entrained in subduction-zone magmas often record metasomatic signature of the mantle wedge. Such xenoliths occur in magmas from Iraya and Pinatubo volcanoes, located at the volcanic front of the Luzon arc in the Philippines. In this study, we present the major element compositions of the main minerals, trace element abundances in pyroxenes and amphiboles, and Nd-Sr isotopic compositions of amphiboles in the peridotite xenoliths from Pinatubo volcano. The data indicate enrichment in fluid-mobile elements, such as Rb, Ba, U, Pb, and Sr, and Nd-Sr isotopic ratios relative to those of mantle. The results are considered in terms of mixing of asthenospheric mantle and subducting oceanic crustal components. The enrichments observed in the Pinatubo mantle xenoliths are much less pronounced than those reported for the Iraya mantle xenoliths. This disparity suggests differences in the metasomatic agents contributing to the two suites; i.e., aqueous fluids infiltrated the mantle wedge beneath the Pinatubo volcano, whereas aqueous fluids and sediment-derived melts infiltrated the mantle wedge beneath the Iraya volcano.

  6. The effect of shoe design and lateral wedging on knee loading

    DEFF Research Database (Denmark)

    Mølgaard, Carsten; Kersting, Uwe G.

    The increasing number of patients with developing osteoarthritis is accompanied by a growing scientific interest in non-operative early treatment strategies. It is generally believed that laterally wedged insoles can change the distribution of the knee loading, but the importance of footwear design......-dimensional gait analysis. Barefoot walking, walking in a running shoe, an Oxford-type leather shoe, and a rocker shoe were analyzed. The shoes were tested both with and without a 10-degree full length laterally wedged insole. Results: Similar, significant reductions in the peak knee adduction moment with lateral...... wedges were observed in all three types of shoes. However, differences between shoe design were of similar magnitude as the effect of laterally wedged insoles. Only marginal changes in muscle activity for lateral hamstrings during barefoot toe-out walking and gastrocnemius when using the Oxford wedged...

  7. Bonding mechanism of ultrasonic wedge bonding of copper wire on Au/Ni/Cu substrate

    Institute of Scientific and Technical Information of China (English)

    TIAN Yan-hong; WANG Chun-qing; Y. Norman ZHOU

    2008-01-01

    The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature. Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX, pull test, shear test and microhardness test. The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing. The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible, and the wedge bonding is achieved by wear action induced by ultrasonic vibration. The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.

  8. Intraplate volcanism and mantle dynamics in East Asia: Big mantle wedge (BMW) model (Invited)

    Science.gov (United States)

    Zhao, D.

    2009-12-01

    In the East Asia continent there are many Cenozoic volcanoes, but only a few are still active now, such as the Changbai, Wudalianchi, and Tengchong volcanoes which have erupted several times in the past 1000 years. Although many studies have been made by using various approaches, the origin of the intraplate volcanoes in East Asia is still not very clear. Recently we used regional and global seismic tomography to determine high-resolution 3-D mantle structure under Western Pacific to East Asia (Zhao, 2004; Huang and Zhao, 2006; Zhao et al., 2009). Our results show prominent low-velocity anomalies from the surface down to 410 km depth beneath the intraplate volcanoes and a broad high-velocity anomaly in the mantle transition zone under East Asia. Focal-mechanism solutions of deep earthquakes indicate that the subducting Pacific slab under the Japan Sea and the East Asia margin is subject to compressive stress regime. These results suggest that the Pacific slab meets strong resistance at the 660-km discontinuity and so it becomes stagnant in the mantle transition zone under East Asia. The Philippine Sea slab has also subducted down to the mantle transition zone under western Japan and the Ryukyu back-arc region. The western edge of the stagnant slab is generally parallel with the Japan trench and the Ryukyu trench and roughly coincides with a prominent surface topography and gravity boundary in East China, which is located approximately 1800 km west of the trenches. The upper mantle under East Asia has formed a big mantle wedge (BMW) above the stagnant slab. The BMW exhibits low seismic-velocity and high electrical-conductivity, which is hot and wet because of the deep dehydration reactions of the stagnant slab and the convective circulation process in the BMW. These processes lead to the upwelling of hot and wet asthenospheric materials and thinning and fracturing of the continental lithosphere, leading to the formation of the active intraplate volcanoes in East

  9. Grounded cognition.

    Science.gov (United States)

    Barsalou, Lawrence W

    2008-01-01

    Grounded cognition rejects traditional views that cognition is computation on amodal symbols in a modular system, independent of the brain's modal systems for perception, action, and introspection. Instead, grounded cognition proposes that modal simulations, bodily states, and situated action underlie cognition. Accumulating behavioral and neural evidence supporting this view is reviewed from research on perception, memory, knowledge, language, thought, social cognition, and development. Theories of grounded cognition are also reviewed, as are origins of the area and common misperceptions of it. Theoretical, empirical, and methodological issues are raised whose future treatment is likely to affect the growth and impact of grounded cognition.

  10. Two-dimensional electronic spectroscopy with birefringent wedges

    Energy Technology Data Exchange (ETDEWEB)

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio [IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2014-12-15

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria.

  11. The use of sternal wedge osteotomy in pectus surgery: when is it necessary?

    Science.gov (United States)

    Kara, Murat; Gundogdu, Ahmet Gokhan; Kadioglu, Salih Zeki; Cayirci, Ertug Can; Taskin, Necati

    2016-09-01

    The Ravitch procedure is a well-established surgical procedure for correction of chest wall deformities. Sternal wedge osteotomy is an important part of this procedure. We studied the incidence of wedge osteotomy with respect to the type of chest wall deformity in patients undergoing surgical correction with the use of a recently developed chest wall stabilization system. A total of 47 patients, 39 (83%) male and 8 (17%) female with a mean age of 14.9 ± 2.1 years, underwent the Ravitch procedure. Twenty-four (51.1%) had pectus carinatum, 19 (40.4%) had pectus excavatum, and 4 (8.5%) had pectus arcuatum. A conventional or oblique sternal wedge osteotomy was performed as indicated, followed by chest wall stabilization using the MedXpert system. Of the 47 patients, 27 (57.4%) had a sternal wedge osteotomy. All cases of pectus arcuatum and redo cases underwent sternal wedge osteotomy. Pectus excavatum cases tended to have a greater incidence of wedge osteotomy compared to pectus carinatum cases (68.4% vs. 41.7%, p = 0.052). Patients with more resected ribs had a greater rate of wedge osteotomy (63.4%) compared to those with fewer resected ribs (16.7%, p = 0.043). A sternal wedge osteotomy is more commonly performed in patients with pectus excavatum compared to those with pectus carinatum. All redo and pectus arcuatum cases need a wedge osteotomy for proper correction. Wedge osteotomy is very likely in more aggressive corrections with more rib resections. © The Author(s) 2016.

  12. Seaward- Versus Landward-Verging Thrusts in Accretionary Wedges: A Numerical Modeling Study of the Effects of Heterogeneity in Pore Fluid Pressure and Frictional Strength

    Science.gov (United States)

    Ito, G.; Moore, G. F.; Olive, J. A. L.; Weiss, J. R.

    2015-12-01

    Whereas seaward-verging thrust faults are, by far, the most common large faults associated with accretionary wedges, the importance of the globally rare, landward verging thrusts has recently been highlighted given the prominence of landward vergence along the Cascadia margin as well as along the Andaman-Sumatra subduction zone, especially in the rupture area of the great 2004 earthquake. The mechanical processes that lead to seaward- versus landward-verging thrusts in accretionary wedges has long been a topic of debate. A weak frictional décollement is one explanation that indeed promotes landward vergence, but not only so, because the typical pattern is of dual verging conjugate faults. A non-brittle, ductile décollement is a second explanation that has been shown in the laboratory to produce a wide sequence of only landward-verging thrusts, but the mechanical causes are not well understood and numerical modeling studies have yet to reproduce this behavior. A seaward-dipping backstop is a third explanation; it promotes landward vergence locally, but more distally the backstop effects diminish and the sense of vergence transitions back to seaward. Mohr-Coulomb and minimum work theory predict that landward vergence should predominate when the direction of maximum principal compression dips landward. We hypothesize that such a condition can arise due to the migration of pore fluids and the associated spatial heterogeneity in frictional strength within the wedge. We test this hypothesis using 2-D numerical models that use a finite-difference, particle-in-cell method for simulating the deformation of an accretionary wedge with a viscoelastic-plastic rheology. With a uniform internal frictional strength, the calculations reproduce many of the faulting behaviors seen in prior laboratory and numerical modeling studies. We are exploring the impacts of heterogeneity in pore fluid pressure and frictional strength on the pattern and vergence of thrust faults.

  13. Vertebral body or intervertebral disc wedging: which contributes more to thoracolumbar kyphosis in ankylosing spondylitis patients?

    Science.gov (United States)

    Liu, Hao; Qian, Bang-Ping; Qiu, Yong; Wang, Yan; Wang, Bin; Yu, Yang; Zhu, Ze-Zhang

    2016-01-01

    Abstract Both vertebral body wedging and disc wedging are found in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis. However, their relative contribution to thoracolumbar kyphosis is not fully understood. The objective of this study was to compare different contributions of vertebral and disc wedging to the thoracolumbar kyphosis in AS patients, and to analyze the relationship between the apical vertebral wedging angle and thoracolumbar kyphosis. From October 2009 to October 2013, a total of 59 consecutive AS patients with thoracolumbar kyphosis with a mean age of 38.1 years were recruited in this study. Based on global kyphosis (GK), 26 patients with GK < 70° were assigned to group A, and the other 33 patients with GK ≥ 70° were included in group B. Each GK was divided into disc wedge angles and vertebral wedge angles. The wedging angle of each disc and vertebra comprising the thoracolumbar kyphosis was measured, and the proportion of the wedging angle to the GK was calculated accordingly. Intergroup and intragroup comparisons were subsequently performed to investigate the different contributions of disc and vertebra to the GK. The correlation between the apical vertebral wedging angle and GK was calculated by Pearson correlation analysis. The duration of disease and sex were also recorded in this study. With respect to the mean disease duration, significant difference was observed between the two groups (P < 0.01). The wedging angle and wedging percentage of discs were significantly higher than those of vertebrae in group A (34.8° ± 2.5° vs 26.7° ± 2.7°, P < 0.01 and 56.6% vs 43.4%, P < 0.01), whereas disc wedging and disc wedging percentage were significantly lower than vertebrae in group B (37.6° ± 7.0° vs 50.1° ± 5.1°, P < 0.01 and 42.7% vs 57.3%, P < 0.01). The wedging of vertebrae was significantly higher in group B than in group A (50.1° ± 5.1° vs 26.7° ± 2.7°, P < 0

  14. The uncomfortable comfort zone

    Directory of Open Access Journals (Sweden)

    Carlos Renato Zacharias

    2012-04-01

    Full Text Available Whenever we achieve the satisfaction of our expectations and anxiety dissolves, we feel as if we were in a comfort zone – safe, complete, free from risks and in peace with ourselves. We might even have a little taste of heaven when we feel that we have fulfilled our duty. And as a fact, scientists are entitled to this kind of reward… but not for too long! In science, to enter a comfort zone can be as pleasant as dangerous. On one hand we may have a safe ground available to develop new modes of reasoning, protocols and theories. And on the other, we may stay stuck in a conventional but fragile ground, missing opportunities to reveal novel secrets or to address edge issues. ... The community of HD researchers seems to have entered a new comfort zone when nanostructures were found in HD. Nanostructures have been raised to the level of ultimate evidence doing away with Avogadro’s limit and leading homeopathy and HD research into mainstream science. We really should enjoy this moment and collect more information about the HD phenomenon. However, we must be wary to not fall into a trap.

  15. Mechanism of bone incorporation of beta-TCP bone substitute in open wedge tibial osteotomy in patients.

    NARCIS (Netherlands)

    Gaasbeek, R.D.A.; Toonen, H.G.; Heerwaarden, R.J. van; Buma, P.

    2005-01-01

    A histological study was performed of bone biopsies from 16 patients (17 biopsies) treated with open wedge high tibial osteotomies for medial knee osteoarthritis. The open wedge osteotomies were filled with a wedge of osteoconductive beta tricalcium phosphate (beta-TCP) ceramic bone replacement. At

  16. Report to Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1996 breeding ground surveys of geese, swans and sandhill cranes in the coastal zone, Yukon-Kuskokwim delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of nesting geese, swans and sandhill cranes were conducted in the coastal zone of the Yukon-Kuskokwim Delta for the 12th consecutive year. The survey...

  17. Report to Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1993 breeding ground surveys of geese and swans in the coastal zone, Yukon-Kuskokwim Delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of geese nesting in the coastal zone of the Yukon Kuskokwim Delta w-ere conducted for the ninth consecutive year. The population response of emperor...

  18. Report to Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1992 breeding ground surveys of geese and swans in the coastal zone, Yukon-Kuskokwim delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of geese nesting in the coastal zone of the Yukon-Kuskokwim Delta were conducted for the eighth consecutive year. The survey was flown from 11 - 19...

  19. Report to Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1994 breeding ground surveys of geese and swans in the coastal zone, Yukon-Kuskokwim delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of geese nesting in the coastal zone of the Yukon Kuskokwim Delta were conducted for the tenth consecutive year. The survey was flown from 2 - 10...

  20. Swath_1m.tif - Composite interferometric backscatter mosaic collected by the U.S. Geological Survey in Woods Hole, MA in Middle Ground, MA, 201 (UTM Zone 19N, WGS 84, GeoTIFF, 1-m resolution)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data were collected under a cooperative agreement between the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS),...

  1. Report to the Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1999 breeding ground survyes of geese, swans and sandhill cranes in the coastal zone of the Yukon-Kuskokwim Delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of nesting geese, tundra swans, and sandhill cranes were conducted in the coastal zone of the Yukon-Kuskokwim Delta for the 15th consecutive year. The...

  2. Report to Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1991 breeding ground surveys of geese and swans in the coastal zone, Yukon-Kuskokwim Delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of geese nesting in the coastal zone of the Yukon Kuskokwim Delta were conducted for the seventh consecutive year. The survey was flown from 6 June13...

  3. Report to Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-1995 breeding ground surveys of geese and swans in the coastal zone, Yukon-Kuskokwim Delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of nesting geese, swans and sandhill cranes in the coastal zone of the Yukon-Kuskokwim Delta were conducted for the eleventh consecutive year. The...

  4. Report to the Pacific Flyway Study Committee and Waterfowl Conservation Committee on the 1985-2000 breeding ground survyes of geese, swans and sandhill cranes in the coastal zone of the Yukon-Kuskokwim Delta, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys of geese, tundra swans, and sandhill cranes were conducted in the coastal zone of the Yukon-Kuskokwim Delta for the 16th consecutive year. The survey...

  5. Holocene earthquakes and right-lateral slip on the left-lateral Darrington-Devils Mountain fault zone, northern Puget Sound, Washington

    Science.gov (United States)

    Personius, Stephen F.; Briggs, Richard W.; Nelson, Alan R.; Schermer, Elizabeth R; Maharrey, J. Zebulon; Sherrod, Brian; Spaulding, Sarah A.; Bradley, Lee-Ann

    2014-01-01

    Sources of seismic hazard in the Puget Sound region of northwestern Washington include deep earthquakes associated with the Cascadia subduction zone, and shallow earthquakes associated with some of the numerous crustal (upper-plate) faults that crisscross the region. Our paleoseismic investigations on one of the more prominent crustal faults, the Darrington–Devils Mountain fault zone, included trenching of fault scarps developed on latest Pleistocene glacial sediments and analysis of cores from an adjacent wetland near Lake Creek, 14 km southeast of Mount Vernon, Washington. Trench excavations revealed evidence of a single earthquake, radiocarbon dated to ca. 2 ka, but extensive burrowing and root mixing of sediments within 50–100 cm of the ground surface may have destroyed evidence of other earthquakes. Cores in a small wetland adjacent to our trench site provided stratigraphic evidence (formation of a laterally extensive, prograding wedge of hillslope colluvium) of an earthquake ca. 2 ka, which we interpret to be the same earthquake documented in the trenches. A similar colluvial wedge lower in the wetland section provides possible evidence for a second earthquake dated to ca. 8 ka. Three-dimensional trenching techniques revealed evidence for 2.2 ± 1.1 m of right-lateral offset of a glacial outwash channel margin, and 45–70 cm of north-side-up vertical separation across the fault zone. These offsets indicate a net slip vector of 2.3 ± 1.1 m, plunging 14° west on a 286°-striking, 90°-dipping fault plane. The dominant right-lateral sense of slip is supported by the presence of numerous Riedel R shears preserved in two of our trenches, and probable right-lateral offset of a distinctive bedrock fault zone in a third trench. Holocene north-side-up, right-lateral oblique slip is opposite the south-side-up, left-lateral oblique sense of slip inferred from geologic mapping of Eocene and older rocks along the fault zone. The cause of this slip reversal is

  6. Verification of Varian Enhanced Dynamic Wedge implementation in masterplan treatment planning system.

    Science.gov (United States)

    Pasquino, Massimo; Casanova Borca, Valeria; Tofani, Santi; Ozzello, Franca

    2009-04-22

    This paper investigates the accuracy of the two available calculation algorithms of the Oncentra MasterPlan three-dimensional treatment planning system (TPS)-- the pencil beam method and collapsed-cone convolution--in modeling the Varian enhanced dynamic wedge (EDW). Measurements were carried out for a dual high energy (6-15 MV) Varian DHX-S linear accelerator using ionization chambers for beam axis measurements (wedge factors and depth doses), film dosimetry for off-axis dose profiles measurements, and a diode matrix detector for two dimensional absolute dose distributions. Using both calculation algorithms, different configuration of symmetric and asymmetric fields varying the wedge's angle were tested. Accuracy of the treatment planning system was evaluated in terms of percentage differences between measured and calculated values for wedge factors, depth doses, and profiles. As far as the absolute dose distribution was concerned, the gamma index method (Low et al.) was used with 3% and 3 mm as acceptance criteria for dose difference and distance-to-agreement, respectively. Wedge factors and percentage depth doses were within 1% deviation between calculated and measured values. The comparison of measured and calculated dose profiles shows that the Van Dyk's acceptance criteria (Van Dyk et al.) are generally met; a disagreement can be noted for large wedge angles and field size limited to the low dose-low gradient region only. The 2D absolute dose distribution analysis confirms the good accuracy of the two calculation algorithms in modeling the enhanced dynamic wedge.

  7. Dissolved organic carbon (DOC in Arctic ground ice

    Directory of Open Access Journals (Sweden)

    M. Fritz

    2015-01-01

    Full Text Available Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC and nutrients which have been accumulated in late Pleistocene and Holocene unconsolidated deposits. Their vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change is largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC, dissolved inorganic carbon (DIC and other elements, which are important for ecosystems and carbon cycling. Here we show, using geochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage with a maximum of 28.6 mg L−1 (mean: 9.6 mg L−1. Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly stored in ground ice, especially in ice wedges, even before further degradation. In the Yedoma region ice wedges represent a significant DOC (45.2 Tg and DIC (33.6 Tg pool in permafrost areas and a fresh-water reservoir of 4172 km3. This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost carbon pool for ecosystems and climate feedback upon mobilization.

  8. Ground Wars

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Kleis

    Political campaigns today are won or lost in the so-called ground war--the strategic deployment of teams of staffers, volunteers, and paid part-timers who work the phones and canvass block by block, house by house, voter by voter. Ground Wars provides an in-depth ethnographic portrait of two...... infrastructures that utilize large databases with detailed individual-level information for targeting voters, and armies of dedicated volunteers and paid part-timers. Nielsen challenges the notion that political communication in America must be tightly scripted, controlled, and conducted by a select coterie...... of professionals. Yet he also quashes the romantic idea that canvassing is a purer form of grassroots politics. In today's political ground wars, Nielsen demonstrates, even the most ordinary-seeming volunteer knocking at your door is backed up by high-tech targeting technologies and party expertise. Ground Wars...

  9. Characteristic Study on Cool Storage in Transition Period of Cooling Tower-Ground Coupled Heat Pump in Hot-summer and Cold-winter Zone%夏热冬冷地区冷却塔—土壤耦合热泵过渡季蓄冷特性研究

    Institute of Scientific and Technical Information of China (English)

    谢莉; 刘金祥; 刘凯

    2013-01-01

    This paper proposes a soil cool storage model for cooling tower-ground coupled heat pump in transition period based on cooling and heating load characteristics in hot-summer and cold-winter zone,establishes a simulation model for the soil cool storage system of cooling tower-ground coupled heat pump in transition period by means of software TRNSYS,conducts working condition simulation analysis of the two main influencing factors of the model regarding soil cool storage in transition period and proposes a control strategy regarding soil cool storage in transition period for cooling tower-ground coupled heat pump.Besides,this paper also strives to explore an effective method to relieve yearly thermal imbalance of ground-source heat pump in hot-summer and cold-winter zone and improve system operation efficiency based on the researches above.%本文针对夏热冬冷地区冷热负荷特性,提出了冷却塔—土壤耦合热泵过渡季土壤蓄冷模式,采用软件TRNSYS建立了冷却塔—土壤耦合热泵过渡季土壤蓄冷系统仿真模型,并利用该模型针对过渡季土壤蓄冷的两个主要影响因素进行了工况模拟分析,,在此基础上提出了冷却塔—土壤耦合热泵过渡季节土壤蓄冷的控制策略.本文力图通过上述研究探索出缓解夏热冬冷地区土壤源热泵系统全年热失衡问题、提高该系统运行效率的有效途径.

  10. Experimental Investigation on Cross Flow of Wedge-shaped Gap in the core of Prismatic VHTR

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Hun; Park, Goon Cherl; Cho, Hyoung Kyu [Seoul National University, Seoul (Korea, Republic of); Yoon, Su Jong [Idaho National Laboratory, Idaho Falls (United States)

    2014-10-15

    The core of the PMR type reactor consists of assemblies of hexagonal graphite blocks. The graphite blocks have lots of advantages for neutron economy and high temperature structural integrity. The height and flat-to-flat width of fuel bock are 793 mm and 360 mm, respectively. Each block has 108 coolant channels of which the diameter is 16 mm. And there are gaps between blocks not only vertically but also horizontally for reloading of the fuel elements. The vertical gap induces the bypass flow and through the horizontal gap the cross flow is formed. Since the complicated flow distribution occurs by the bypass flow and cross flow, flow characteristics in the core of the PMR reactor cannot be treated as a simple pipe flow. The fuel zone of the PMR core consists of multiple layers of fuel blocks. The shape change of the fuel blocks could be caused by the thermal expansion and fast-neutron induced shrinkage. It could make different axial shrinkage of fuel block and this leads to wedge-shaped gaps between two stacked fuel blocks. The cross flow is often considered as a leakage flow through the horizontal gap between stacked fuel blocks and it complicates the flow distribution in the reactor core by connecting the coolant channel and the bypass gap. Moreover, the cross flow could lead to uneven coolant distribution and consequently cause superheating of individual fuel element zones with increased fission product release. Since the core cross flow has a negative impact on safety and efficiency of VHTR, core cross flow phenomena have to be investigated to improve the core thermal margin of VHTR. To develop the cross flow loss coefficient model for determination of the flow distribution for PMR core analysis codes, study on cross flow for PMR200 core is essential. In particular, to predict the amount of flow through the cross flow gap, obtaining accurate flow loss coefficient is important. In this study, the full-scale cross flow experimental facility was constructed to

  11. Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period.

    Science.gov (United States)

    Klages, Johann P; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Smith, James A; Graham, Alastair G C; Nitsche, Frank O; Frederichs, Thomas; Jernas, Patrycja E; Gohl, Karsten; Wacker, Lukas

    2017-01-01

    Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5-19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated. In many areas of the outer continental shelf around Antarctica, direct geological data for the presence or absence of grounded ice during the LGM is lacking because of post-LGM iceberg scouring. This also applies to most of the outer continental shelf in the Amundsen Sea. Here we present detailed marine geophysical and new geological data documenting a sequence of glaciomarine sediments up to ~12 m thick within the deep outer portion of Abbot Trough, a palaeo-ice stream trough on the outer shelf of the Amundsen Sea Embayment. The upper 2-3 meters of this sediment drape contain calcareous foraminifera of Holocene and (pre-)LGM age and, in combination with palaeomagnetic age constraints, indicate that continuous glaciomarine deposition persisted here since well before the LGM, possibly even since the last interglacial period. Our data therefore indicate that the LGM grounding line, whose exact location was previously uncertain, did not reach the shelf edge everywhere in the Amundsen Sea. The LGM grounding line position coincides with the crest of a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, an area of ≥6000 km2 remained free of grounded ice through the last glacial cycle, requiring the LGM grounding line position to be re-located in this sector, and suggesting a new site at which Antarctic shelf benthos may have survived the last glacial period.

  12. One-way successive plate cross wedge rolling machine

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In our last paper(Sci China Ser E-Tech Sci,2009,52(11):3117-3121) we designed the precision forming machine with rolling plate CWR(cross wedge rolling).This kind of machine colligates the advantages of high rigidity and small floor space for roller CWR machine and those of simple die manufacture and high precision for plate CWR machine.At the same time,it abandons the shortcomings of complex die manufacture and poor precision for roller CWR machine,and those of poor rigidity and large floor space for plate CWR machine.During rolling,the upper and lower rolling plates of the machine make reciprocating slide toward or away from each other,so the inertial forces should be overcome,which will cause great energy loss,besides,large floor space is needed when the rolled workpiece is large.In order to solve the above problems,this paper presents the one-way successive plate CWR machine,whose rolling plates need not make reciprocating slide.Hence,it has high energy utilization efficiency and production efficiency.Furthermore,the roll scale can be removed automatically.In particular,the machine can produce large axisymmetrical workpieces.

  13. Sinking, wedging, spreading - viscous spreading on a layer of fluid

    Science.gov (United States)

    Bergemann, Nico; Juel, Anne; Heil, Matthias

    2016-11-01

    We study the axisymmetric spreading of a sessile drop on a pre-existing layer of the same fluid in a regime where the drop is sufficiently large so that the spreading is driven by gravity while capillary and inertial effects are negligible. Experiments performed with 5 ml drops and layer thicknesses in the range 0.1 mm drop evolves as R tn , where the spreading exponent n increases with the layer thickness h. Numerical simulations, based on the axisymmetric free-surface Navier-Stokes equations, reveal three distinct spreading regimes depending on the layer thickness. For thick layers the drop sinks into the layer, accompanied by significant flow in the layer. By contrast, for thin layers the layer ahead of the propagating front is at rest and the spreading behaviour resembles that of a gravity-driven drop spreading on a dry substrate. In the intermediate regime the spreading is characterised by an advancing wedge, which is sustained by fluid flow from the drop into the layer.

  14. Precision forming machine with rolling plate cross wedge rolling

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Roller cross wedge rolling(CWR)machines have high rigidity, but sector dies are difficult to process. Plate CWR machines have low rigidity and need large floor space, but plate dies are easy to process. Neither roller CWR machine nor plate CWR machine can produce larger workpieces. Based on the above conclusions, this paper presents the mechanical principle of the precision forming machine with rolling plate CWR. Then, its design principle and machine construction are presented. There are a top press roller above the upper sliding plate and a bottom press roller under the lower sliding plate. The press rollers make rolling contact with the sliding plates. The plate dies are mounted on the upper and lower sliding plates, respectively. Furthermore, the axes of both press rollers and centerline of work-piece always keep in the identical vertical plane during forming process. These make the machine retain advantages of high rigidity for roller CWR machine and simpleness of manufacturing dies for plate CWR machine, and abandon defects of poor rigidity for plate CWR machine and difficulty of manufac-turing dies for roller CWR machine. Moreover, the machine can produce larger workpieces.

  15. Lateral closed wedge osteotomy for cubitus varus deformity

    Directory of Open Access Journals (Sweden)

    Srivastava Amit

    2008-01-01

    Full Text Available Background: Lateral closed wedge (LCW osteotomy is a commonly accepted method for the correction of the cubitus varus deformity. The fixation of osteotomy is required to prevent loss of correction achieved. The fixation of the osteotomy by the two screw and figure of eight wire is not stable enough to maintain the correction achieved during surgery. In this prospective study we supplemented the fixation by Kirschner′s (K- wires for stable fixation and evaluated the results. Materials and Methods: Twenty-one cases of the cubitus varus deformity following supracondylar fractures of the humerus were operated by LCW osteotomy during February 2001 to June 2006. The mean age of the patients at the time of corrective surgery was 8.5 years (range 6.6-14 years. The osteotomy was fixed by two screws with figure of eight tension band wire between them and the fixation was supplemented by passing two to three K-wires from the lateral condyle engaging the proximal medial cortex through the osteotomy site. Result: The mean follow-up period was 2.5 years (range seven months to 3.4 years. The results were assessed as per Morrey criteria. Eighteen cases showed excellent results and three cases showed good results. Two cases had superficial pin tract infection. Conclusion: The additional fixation by K wires controls rotational forces effectively besides angulation and translation forces and maintains the correction achieved peroperatively.

  16. Precision forming machine with rolling plate cross wedge rolling

    Institute of Scientific and Technical Information of China (English)

    SONG YuQuan; LI ZhiGang; WANG MingHui; GUAN XiaoFang

    2009-01-01

    Roller cross wedge rolling (CWR) machines have high rigidity, but sector dies are difficult to process.Plate CWR machines have low rigidity and need large floor space, but plate dies are easy to process.Neither roller CWR machine nor plate CWR machine can produce larger workpieces.Based on the above conclusions, this paper presents the mechanical principle of the precision forming machine with rolling plate CWR.Then, its design principle and machine construction are presented.There are a top press roller above the upper sliding plate and a bottom press roller under the lower sliding plate.The press rollers make rolling contact with the sliding plates.The plate dies are mounted on the upper and lower sliding plates, respectively.Furthermore, the axes of both press rollers and centerline of work-piece always keep in the identical vertical plane during forming process.These make the machine re-tain advantages of high rigidity for roller CWR machine and simpleness of manufacturing dies for plate CWR machine, and abandon defects of poor rigidity for plate CWR machine and difficulty of manufac-turing dies for roller CWR machine.Moreover, the machine can produce larger workpieces.

  17. Influence of intermolecular forces at critical-point wedge filling.

    Science.gov (United States)

    Malijevský, Alexandr; Parry, Andrew O

    2016-04-01

    We use microscopic density functional theory to study filling transitions in systems with long-ranged wall-fluid and short-ranged fluid-fluid forces occurring in a right-angle wedge. By changing the strength of the wall-fluid interaction we can induce both wetting and filling transitions over a wide range of temperatures and study the order of these transitions. At low temperatures we find that both wetting and filling transitions are first order in keeping with predictions of simple local effective Hamiltonian models. However close to the bulk critical point the filling transition is observed to be continuous even though the wetting transition remains first order and the wetting binding potential still exhibits a small activation barrier. The critical singularities for adsorption for the continuous filling transitions depend on whether retarded or nonretarded wall-fluid forces are present and are in excellent agreement with predictions of effective Hamiltonian theory even though the change in the order of the transition was not anticipated.

  18. Influence of intermolecular forces at critical-point wedge filling

    Science.gov (United States)

    Malijevský, Alexandr; Parry, Andrew O.

    2016-04-01

    We use microscopic density functional theory to study filling transitions in systems with long-ranged wall-fluid and short-ranged fluid-fluid forces occurring in a right-angle wedge. By changing the strength of the wall-fluid interaction we can induce both wetting and filling transitions over a wide range of temperatures and study the order of these transitions. At low temperatures we find that both wetting and filling transitions are first order in keeping with predictions of simple local effective Hamiltonian models. However close to the bulk critical point the filling transition is observed to be continuous even though the wetting transition remains first order and the wetting binding potential still exhibits a small activation barrier. The critical singularities for adsorption for the continuous filling transitions depend on whether retarded or nonretarded wall-fluid forces are present and are in excellent agreement with predictions of effective Hamiltonian theory even though the change in the order of the transition was not anticipated.

  19. Experimental and Numerical Procedures of a Sonar Platform with a Sound Absorption Wedge

    Institute of Scientific and Technical Information of China (English)

    Danzhu Yu; Xiongliang Yao; Shaoshi Dai

    2011-01-01

    Experiments involving a sonar platform with a sound absorption wedge were carried out for the purpose of obtaining the low frequency acoustic characteristics.Acoustic characteristics of a sonar platform model with a sound absorption wedge were measured,and the effects of different wedge laid areas on platform acoustic characteristic were tested.Vibration acceleration and self-noise caused by model vibration were measured in four conditions:0%,36%,60%,and 100% of wedge laid area when the sonar platform was under a single frequency excitation force.An experiment was performed to validate a corresponding numerical calculation.The numerical vibration characteristics of platform area were calculated by the finite element method,and self-noise caused by the vibration in it was predicted by an experiential formula.The conclusions prove that the numerical calculation method can partially replace the experimental process for obtaining vibration and sound characteristics.

  20. Fabrication and Determination of Refractive Index Profile of the Planar Waveguides by Wedge Technique

    Institute of Scientific and Technical Information of China (English)

    S.; M.; R.; Sadat; Hosseini; A.; Darudi

    2003-01-01

    Several planar waveguides have been fabricated. The waveguides have been polished for determination of their refractive index profiles (RIP) by wedge method. The RIP determined by inserting the sample in a Mach-Zehnder interferometer and applying fringe analysis methods.

  1. Fabrication and Determination of Refractive Index Profile of the Planar Waveguides by Wedge Technique

    Institute of Scientific and Technical Information of China (English)

    S. M. R. Sadat Hosseini; A. Darudi

    2003-01-01

    Several planar waveguides have been fabricated. The waveguides have been polished for determination of their refractiveindex profiles (RIP) by wedge method. The RIP determined by inserting the sample in a Mach-Zehnder interferometer andapplying fringe analysis methods.

  2. Development of Cone Wedge Ring Expansion Test to Evaluate Mechanical Properties of Clad Tubing Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    To determine the hoop tensile properties of irradiated fuel cladding in a hot cell, a cone wedge ring expansion test method was developed. A four-piece wedge insert was designed with tapered angles matched to the cone shape of a loading piston. The ring specimen was expanded in the radial direction by the lateral expansion of the wedges under the downward movement of the piston. The advantages of the proposed method are that implementation of the test setup in a hot cell is simple and easy, and that it enables a direct strain measurement of the test specimen from the piston’s vertical displacement soon after the wedge-clad contact resistance is initiated.

  3. Distal femoral varus osteotomy: problems associated with the lateral open-wedge technique.

    Science.gov (United States)

    Jacobi, Matthias; Wahl, Peter; Bouaicha, Samy; Jakob, Roland P; Gautier, Emanuel

    2011-06-01

    Varisation osteotomies on the distal femur are an established treatment method for valgus osteoarthritis of the knee in younger patients. Osteotomy can be done in a lateral open-wedge or medial closed-wedge manner. We retrospectively studied 14 patients treated by the lateral open-wedge technique, fixed with the Tomofix plate, with a mean duration of follow-up of 45 ± 3.4 months. We observed often delayed osteotomy healing after 3, 6 and 12 months, no secondary dislocations, and frequent troublesome irritation due to the plate being on the iliotibial band. However, outcome was satisfactory once the osteotomy healed and the plate was removed. Based on the often slow healing of the osteotomy and frequent irritation due to the plate, this procedure has been abandoned by the authors, and the medial closing-wedge osteotomy adopted as the alternative treatment.

  4. Medial opening wedge distal femoral osteotomy for post-traumatic secondary knee osteoarthritis.

    Science.gov (United States)

    Matsui, Gen; Akiyama, Takenori; Ikemura, Satoshi; Mawatari, Taro

    2014-04-30

    Osteoarthritis of the knee secondary to femoral fracture is difficult to treat. There are some surgical options, such as total knee arthroplasty or correction osteotomy. Opening wedge high tibial osteotomy is an established treatment of gonarthrosis. However, few reports are available on the effectiveness of a medial opening wedge distal femoral osteotomy. We present a case of a medial opening wedge distal femoral osteotomy on gonarthrosis secondary to a malunited femoral fracture with varus deformity and leg length discrepancy. This osteotomy was performed at the deformed femur, with locking plate fixation and autologous bone graft. Six months after the surgery, the osteotomy site was filled with bridging callus. Two years later, the Knee Society Score improved from 45 to 90 points. Medial opening wedge distal femoral osteotomy can be a useful method to treat knee osteoarthritis associated with distal femoral deformity.

  5. Diffraction of an inhomogeneous plane wave by an impedance wedge in a lossy medium

    CSIR Research Space (South Africa)

    Manara, G

    1998-11-01

    Full Text Available The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory...

  6. Second-law analysis of fluid flow over an isothermal moving wedge

    Directory of Open Access Journals (Sweden)

    F. Hedayati

    2014-03-01

    Full Text Available In this study, entropy generation minimization (EGM was employed to optimize fluid flow and heat transfer over a moving wedge. Governing partial differential equations including continuity, momentum and energy are reduced to ordinary ones using similarity variables and solved numerically. The novelty of this study is to consider the effects of the moving wedge parameter λ, to find the stable system via entropy generation minimization (EGM method. The results indicated that as the slope of the wedge increases, the absolute values of the optimum moving wedge parameter λo grow as well. Moreover, it was found that the minimum value of entropy generation happens for the negative values of λo which gets smaller as Falkner–Skan power law parameter m increases.

  7. Optimization of parameters on material removal rate in micro-WEDG ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... Optimization of parameters on material removal rate in micro-WEDG process ... nonconventional machining method for manufacturing accurate and complex three dimensional ...

  8. Study on Mach stems induced by interaction of planar shock waves on two intersecting wedges

    Institute of Scientific and Technical Information of China (English)

    Gaoxiang Xiang; Chun Wang; Honghui Teng; Yang Yang; Zonglin Jiang

    2016-01-01

    The properties of Mach stems in hypersonic corner flow induced by Mach interaction over 3D inter-secting wedges were studied theoretically and numerically. A new method called “spatial dimension reduction” was used to analyze theoretically the location and Mach num-ber behind Mach stems. By using this approach, the problem of 3D steady shock/shock interaction over 3D intersecting wedges was transformed into a 2D moving one on cross sec-tions, which can be solved by shock-polar theory and shock dynamics theory. The properties of Mach interaction over 3D intersecting wedges can be analyzed with the new method, including pressure, temperature, density in the vicinity of triple points, location, and Mach number behind Mach stems. Theoretical results were compared with numerical results, and good agreement was obtained. Also, the influence of Mach number and wedge angle on the properties of a 3D Mach stem was studied.

  9. Strain Measurements within Fibre Boards. Part II: Strain Concentrations at the Crack Tip of MDF Specimens Tested by the Wedge Splitting Method

    Directory of Open Access Journals (Sweden)

    Jörn Rathke

    2012-08-01

    Full Text Available This is the second part of an article series where the mechanical and fracture mechanical properties of medium density fiberboard (MDF were studied. While the first part of the series focused on internal bond strength and density profiles, this article discusses the fracture mechanical properties of the core layer. Fracture properties were studied with a wedge splitting setup. The critical stress intensity factors as well as the specific fracture energies were determined. Critical stress intensity factors were calculated from maximum splitting force and two-dimensional isotropic finite elements simulations of the specimen geometry. Size and shape of micro crack zone were measured with electronic laser speckle interferometry. The process zone length was approx. 5 mm. The specific fracture energy was determined to be 45.2 ± 14.4 J/m2 and the critical stress intensity factor was 0.11 ± 0.02 MPa.

  10. Strain Measurements within Fibre Boards. Part II: Strain Concentrations at the Crack Tip of MDF Specimens Tested by the Wedge Splitting Method

    Science.gov (United States)

    Sinn, Gerhard; Müller, Ulrich; Konnerth, Johannes; Rathke, Jörn

    2012-01-01

    This is the second part of an article series where the mechanical and fracture mechanical properties of medium density fiberboard (MDF) were studied. While the first part of the series focused on internal bond strength and density profiles, this article discusses the fracture mechanical properties of the core layer. Fracture properties were studied with a wedge splitting setup. The critical stress intensity factors as well as the specific fracture energies were determined. Critical stress intensity factors were calculated from maximum splitting force and two-dimensional isotropic finite elements simulations of the specimen geometry. Size and shape of micro crack zone were measured with electronic laser speckle interferometry. The process zone length was approx. 5 mm. The specific fracture energy was determined to be 45.2 ± 14.4 J/m2 and the critical stress intensity factor was 0.11 ± 0.02 MPa.

  11. Tectonic history of continental crustal wedge constrained by EBSD measurements of garnet inclusion trails and thermodynamic modeling

    Science.gov (United States)

    Skrzypek, E.; Schulmann, K.; Lexa, O.; Haloda, J.

    2009-04-01

    Inclusion trails in garnets represent an important but underused tool of structural geology to examine non-coaxial or polyphase coaxial deformation histories of orogens. Garnet growth with respect to deformation during prograde and retrograde orogenic evolution of a continental crustal wedge was constrained by EBSD measurements of internal garnet fabrics and petrological record from mid-crustal rocks of the Śnieżnik Massif (Western Sudetes). Textural position of metamorphic minerals and thermodynamic modeling document three main stages in the tectonic evolution. Few garnet cores show prograde MnO zoning and growth coeval with the formation of the earliest metamorphic foliation which is only rarely observed in the field. The major garnet growth occurs synchronously with the second steep S2 fabric under still prograde conditions as shown by garnet zoning and appearance of staurolite and kyanite (peak at 6,5kbar/600°C). Oppositely, garnet retrogression associated to the development of sillimanite and later andalusite indicates pressure decrease of ca. 3 kbar for the late flat and pervasive S3 fabric associated with macroscopic recumbent folding of steep S2 foliation. Electron back-scatter diffraction measurements on ilmenites platelets included in garnets help determining their crystallographic preferred orientation. Ilmenites a[100] axes define planar structures that are interpreted as included foliations. Consequently, microscopic observations and foliation intersection axes (FIA) allow to distinguish between two different records. Only few (prograde) garnet cores yield information on the orientation of the presumed first metamorphic fabric whereas most of the internal garnet foliations are straight, steep and correspond to relics of originally steep S2 fabric. Importantly, this steep attitude of internal garnet foliations is persistent in both F3 fold hinge and limb zones as well as in zones of complete transposition of S2 into flat S3. Therefore, these

  12. Comparison of the homogeneity of breast dose distributions with and without the medial wedge.

    Science.gov (United States)

    Ikner, C L; Russo, R; Podgorsak, M B; Proulx, G M; Lee, R J

    1998-01-01

    Radiation of the intact breast often requires medial and lateral wedges to improve dose homogeneity of its pyramidal shape and to achieve acceptable cosmesis. There is some concern that radiation scatter from the medial wedge may contribute to cancer in the uninvolved breast, yet treatment without the medial wedge is associated with inhomogeneity of magnitudes that affect cosmesis. These homogeneities are identified on treatment plans generated at the central axis (CAX). It is not known if comparing isodose curves at the central axis reflect homogeneity in superior and inferior planes. A study was undertaken to both examine inhomogeneity with and without the medial wedge, and to determine if plan selection at the CAX was representative of homogeneity above and below the CAX. Ten consecutive patients with early breast cancers had cranial, CAX, and caudal CT images of each breast compared with two wedging conditions, lateral only (LW) and medial and lateral wedged conditions (dual wedges = DW). Dosimetry was optimized at the CAX for DW and LW conditions. Dose distributions and hot spots relative to prescribed dose were compared for cranial, CAX, and caudal images. Mean chest wall separations were measured. Six of ten patients had equivalent LW and DW distributions at the levels examined. Only one of these patients had a single off-axis hot spot > 20%. Six patients had comparable LW and DW dosimetry and acceptable hot spots at the central axis, as well as chest wall separations < or = 22 cm. In conclusion, if isodose configurations are commensurate at the CAX, these patients will have homogeneity above and below the CAX. In patients with chest wall separations < or = 22 cm, treatment without the medial wedge is feasible, sparing the contralateral breast dose with little compromise to inhomogeneity in the treated breast.

  13. Statics of Magnetic Fluid Drop with Compound Magnetic Core in a Wedge-Shaped Channel

    Directory of Open Access Journals (Sweden)

    V. Bashtovoi

    2013-12-01

    Full Text Available A behavior of magnetic fluid drop with compound magnetic core in a wedge-shaped channel was studied experimentally. The study examines influence of magnetic fluid properties, its volume and magnetic field on statics of the system compound magnet – magnetic fluid drop in wedge-shaped channel. The possibility to change the static conditions of such system by altering magnetic field of the core was observed

  14. The effect of foot orthoses and in-shoe wedges during cycling: a systematic review

    OpenAIRE

    Yeo, Boon K; Bonanno, Daniel R

    2014-01-01

    Background The use of foot orthoses and in-shoe wedges in cycling are largely based on theoretical benefits and anecdotal evidence. This review aimed to systematically collect all published research on this topic, critically evaluate the methods and summarise the findings. Methods Study inclusion criteria were: all empirical studies that evaluated the effects of foot orthoses or in-shoe wedges on cycling; outcome measures that investigated physiological parameters, kinematics and kinetics of ...

  15. Cowpea N rhizodeposition and its below-ground transfer to a co-existing and to a subsequent millet crop on a sandy soil of the Sudano-Sahelian eco-zone

    DEFF Research Database (Denmark)

    Laberge, Guillaume; Haussmann, Bettina I.G.; Ambus, Per;

    2011-01-01

    Nitrogen (N) rhizodeposition by cowpea (Vigna unguiculata (L.) Walp) is potentially a large N source in cropping systems of Sub-Saharan Africa. A field experiment was conducted to measure cowpea N rhizodeposition under the conditions of the Sudano-Sahelian zone using direct 15N labelling techniques...

  16. Assessment of a multibeam Fizeau wedge interferometer for Doppler wind lidar.

    Science.gov (United States)

    McKay, Jack A

    2002-03-20

    The Fabry-Perot interferometer is the standard instrument for the direct detection Doppler lidar measurement of atmospheric wind speeds. The multibeam Fizeau wedge has some practical advantages over the Fabry-Perot, such as the linear fringe pattern, and is evaluated for this application. The optimal Fizeau must have a resolving power of 10(6) or more. As the multibeam Fizeau wedge is pushed to such high resolving power, the interference fringes of the device become complicated by asymmetry and secondary maxima. A simple condition for the interferometer plate reflectance, optical gap, and wedge angle reveals whether a set of parameters will yield simple, Airy-like fringes or complex Fizeau fringes. Tilting of the Fizeau wedge improves the fringe shape and permits an extension of the regime of Airy-like fringes to higher resolving power. Sufficient resolving power for the wind lidar application is shown to be possible with a large-gap, low-finesse multibeam Fizeau wedge. Liabilities of the multibeam Fizeau wedge in the wind lidar application include a smaller acceptance solid angle and calibration sensitivity to localized deviations of the plates from the ideal.

  17. EFFECT OF SALT WEDGE INTRUSION IN KUSHIRO WETLAND CONSIDERING SEA LEVEL RISE

    Science.gov (United States)

    Nakamoto, Atsushi; Shintani, Tetsuya; Nakayama, Keisuke; Maruya, Yasuyuki; Ishida, Tetsuya; Houmura, Kenichi

    This paper describes the effect of sea-level rise (SLR) on the salt wedge intrusion in terms of ecological system in Kushiro wetland. Kushiro wetland was registered by Ramsar Treaty and the largest wetland in Japan. A previous study demonstrates that the salt wedge intrusion may not affect ecological system of Kushiro wetland, such as loss of freshwater plants along Kushiro River. However, it is revealed that SLR may occur in the end of the 21st century, which enhances the increase in the distance of the salt wedge intrusion along Kushiro River and the loss of endangered species of Kushiro wetland along Kushiro River. This study thus aims to investigate the influence of the salt wedge intrusion on freshwater plants along Kushiro River, and to clarify the salt wedge intrusion when SLR occurs due to climate change. We attempted to investigate the influence of SLR on endangered species along Kyu-Kushiro River in which sea water is likely to intrude up to about 8 km from the river mouth. As results, it is suggested from field observations that salinity may decrease freshwater plants along Kushiro River, and it clarifies the possibility that the salt wedge intrudes Kushiro River due to SLR by using 3D hydrodynamic model, Fantom3D.

  18. Experimental study of slot jet impingement heat transfer on a wedge-shaped surface

    Science.gov (United States)

    Rahimi, Mostafa; Irani, Mohammad

    2012-12-01

    An experimental investigation was conducted to study the convective heat transfer rate from a wedge-shaped surface to a rectangular subsonic air jet impinging onto the apex of the wedge. The jet Reynolds number, nozzle-to-surface distance and the wedge angle were considered as the main parameters. Jet Reynolds number was ranged from 5,000 to 20,000 and two dimensionless nozzle-to-surface distances h/w = 4 and 10 were examined. The apex angle of the wedge ranged from 30° to 180° where the latter case corresponds with that of a flat surface. Velocity profile and turbulence intensity were provided for free jet flow using hot wire anemometer. Local and average Nusselt numbers on the impinged surface are presented for all the configurations. Based on the results presented, the local Nusselt number at the stagnation region increases as the wedge angle is decreased but, it then decreases over the remaining area of the impinged surface. Average Nusselt number over the whole surface is maximum when the wedge angle is 180° (i.e. plane surface) for any jet and nozzle-to-surface configuration.

  19. Improve the transconductance of a graphene field-effect transistor by folding graphene into a wedge

    Science.gov (United States)

    Cao, Guiming; Liu, Weihua; Cao, Meng; Li, Xin; Zhang, Anping; Wang, Xiaoli; Chen, Bangdao

    2016-07-01

    The transport property of a graphene wedge channel is studied theoretically and its leakage current through field emission is estimated when considering the effect of the internal electric field. The transconductance of the graphene transistor is improved from 0.016 to 0.321 μS μm-1 when the graphene is folded into a wedge (with angle of wedge π/6 and radius curvature 2.7 nm at the tip), while the wedge height is much smaller than the space between the top-gate and the channel. The improved transconductance is due to the locally enhanced electric field, which results in a potential well and causes electron accumulation at the wedge tip. The leakage current through field emission J FE shows a super-linear increase with the channel conductive current J DS, where overall the electron supply for the field emission at the wedge tip is improved by the channel bias voltage V DS.

  20. Foot alignments influence the effect of knee adduction moment with lateral wedge insoles during gait.

    Science.gov (United States)

    Sawada, Tomonori; Tokuda, Kazuki; Tanimoto, Kenji; Iwamoto, Yoshitaka; Ogata, Yuta; Anan, Masaya; Takahashi, Makoto; Kito, Nobuhiro; Shinkoda, Koichi

    2016-09-01

    Lateral wedge insoles (LWIs) reduce the peak external knee adduction moment (KAM). However, the efficacy of LWIs is limited in certain individuals for whom they fail to decrease KAM. Possible explanations for a lack of desired LWI response are variations in foot alignments. The purpose of this study was to evaluate whether the immediate biomechanical effects of LWIs depend on individual foot alignments during gait. Fifteen healthy adults participated in this study. Their feet were categorized as normal, pronated, and supinated using the foot posture index. All subjects were subsequently requested to perform a normal gait under barefoot and LWI conditions. A three-dimensional motion analysis system was used to record the kinematic and kinetic data, included peak KAM, KAM impulse (KAAI), center of pressure displacement, and knee-ground reaction force lever arm (KLA). Furthermore, lower limb frontal plane kinematic parameters at the rear foot, ankle, knee, and hip were evaluated. Among all feet, there was no significant difference in the peak KAM and KAAI between the conditions. In contrast, the peak KAM was significantly reduced under the LWI condition relative to the barefoot condition in the normal foot group. Reductions in the peak KAM were correlated with a more lateral center of pressure and reduced KLA. In addition, a reduced KLA was correlated with decreased hip adduction. LWIs significantly reduced the peak KAM in normal feet, indicating that biomechanical effects of LWIs vary between individual foot alignments. Our findings suggest that it is helpful to assess individual foot alignment to ensure adequate insole treatment for patients with knee osteoarthritis.

  1. Active Aerothermoelastic Control of Hypersonic Double-wedge Lifting Surface

    Institute of Scientific and Technical Information of China (English)

    Laith K Abbas; Chen Qian; Piergiovanni Marzocca; Gürdal Zafer; Abdalla Mostafa

    2008-01-01

    Designing reentry space vehicles and high-speed aireraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components. The thermal effects are important since temperature environment brings dramatic influences on the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes and is likely to cause instability, catastrophic failure and oscillations resulting in structural failure due to fatigue. In order to understand the dynamic behaviors of these "hot"structures, a double-wedge lifting surface with combining freeplay and cubic structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed. A third order piston theory aerodynamic isused to estimate the applied nonlinear unsteady aerodynamic loads. Also considered is the loss of torsiunal stiffness that may be incurredby lifting surfaces subject to axial stresses induced by aerodynamic heating. The aerodynamic heating effects are estimated based on theadiabatic wall temperature due to high speed airstreams. As a recently emerging technology, the active aerothermoelastic control isaimed at providing solutions to a large number of problems involving the aeronautica Faerospace flight vehicle structures. To preventsuch damaging phenomena from occurring, an application of linear and nonlinear active control methods on both flutter boundary andpost-flutter behavior has been fulfilled. In this paper, modeling issues as well as numerical simulation have been presented and pertinent conclusions outlined. It is evidenced that a serious loss of torsional stiffness may induce the dynamic instability; however active controlcan be used to expand the flutter boundary and convert unstable limit cycle oscillations (LCO) into the stable LCO and/or to shift the transition between these two states toward higher flight Mach numbers.

  2. Laboratory investigation of water extraction effects on saltwater wedge displacement

    Directory of Open Access Journals (Sweden)

    S. Noorabadi

    2017-12-01

    Full Text Available There is a close connection between saltwater intrusion into aquifers and groundwater extraction. Freshwater extraction in coastal aquifers is one of the most important reasons for the saltwater intrusion into these aquifers. Condition of extraction system such as well depth, discharge rate, saltwater concentration and etc. could affect this process widely. Thus, investigating different extraction conditions comprises many management advantages.  In the present study, the effects of freshwater extraction on saltwater interface displacement have been investigated in a laboratory box. Three different well depths (H were considered with combinations of 3 different extraction rates (Q and 3 saltwater concentrations (C for detailed investigation of the effects of these factors variations on saltwater displacement. SEAWAT model has been used to simulate all the scenarios to numerically study of the process. The experimental and numerical results showed that when the C and Q rates were small and the well depth was shallow, the saltwater interface wouldn’t reach the extraction well, so the extracted water remained uncontaminated. When the C and Q rates were increased and the well was deepened, the salinity of the extracted water became higher. When the Q and C rates were high enough, in the shallow well depth, the final concentration of the extracted water was low but a huge part of the porous media was contaminated by the saltwater, furthermore when the well was deepened enough, the final concentration of the extracted water was increased but a small part of the porous media was contaminated by the saltwater. Finally, the results showed that when the Q and H rates were high enough, the extraction well behaved like a barrier and didn’t allow the advancing saltwater wedge toe to be intruded beyond the wells.

  3. Three-dimensional vertebral wedging in mild and moderate adolescent idiopathic scoliosis.

    Directory of Open Access Journals (Sweden)

    Sophie-Anne Scherrer

    Full Text Available BACKGROUND: Vertebral wedging is associated with spinal deformity progression in adolescent idiopathic scoliosis. Reporting frontal and sagittal wedging separately could be misleading since these are projected values of a single three-dimensional deformation of the vertebral body. The objectives of this study were to determine if three-dimensional vertebral body wedging is present in mild scoliosis and if there are a preferential vertebral level, position and plane of deformation with increasing scoliotic severity. METHODOLOGY: Twenty-seven adolescent idiopathic scoliotic girls with mild to moderate Cobb angles (10° to 50° participated in this study. All subjects had at least one set of bi-planar radiographs taken with the EOS® X-ray imaging system prior to any treatment. Subjects were divided into two groups, separating the mild (under 20° from the moderate (20° and over spinal scoliotic deformities. Wedging was calculated in three different geometric planes with respect to the smallest edge of the vertebral body. RESULTS: Factorial analyses of variance revealed a main effect for the scoliosis severity but no main effect of vertebral Levels (apex and each of the three vertebrae above and below it (F = 1.78, p = 0.101. Main effects of vertebral Positions (apex and above or below it (F = 4.20, p = 0.015 and wedging Planes (F = 34.36, p<0.001 were also noted. Post-hoc analysis demonstrated a greater wedging in the inferior group of vertebrae (3.6° than the superior group (2.9°, p = 0.019 and a significantly greater wedging (p≤0.03 along the sagittal plane (4.3°. CONCLUSIONS: Vertebral wedging was present in mild scoliosis and increased as the scoliosis progressed. The greater wedging of the inferior group of vertebrae could be important in estimating the most distal vertebral segment to be restrained by bracing or to be fused in surgery. Largest vertebral body wedging values obtained in the sagittal plane support

  4. Process Based Explanations for Correlations Between the Structural and Seismic Segmentation of the Cascadia Subduction Wedge

    Science.gov (United States)

    Fuller, C. W.; Brandon, M. T.; Willett, S. D.

    2006-12-01

    Variations in the geological and geophysical characteristics of the Cascadia subduction wedge, the region between the trench and arc, result in along-strike wedge segmentation. We focus on explaining the large-scale structural segmentation and how processes causing this segmentation influence segmentation with respect to the seismic behavior of the wedge and subduction thrust. The relationships we develop illustrate the fundamental interplay of processes controlling long-term structure and short-term seismic behavior. Our conclusions are based on the results of numerical models designed to simulate the growth and evolution of the Cascadia subduction wedge through the accretion of a thin layer of sediment to the basaltic Coast Range Terrane (CRT) of the Cascadia margin. Two aspects of wedge structural segmentation are of interest: (1) segmentation with respect to the location or absence of large, continental shelf, forearc basins, and (2) segmentation with respect to the Coastal Range (CR) structural high. Our models illustrate that the form of the submarine portion of the Cascadia wedge, including the basins or lack thereof, is a consequence of the frictional behavior of this region of wedge, subduction thrust strength, wedge strength, and dip thrust. We propose that basin segments have stronger wedge material, a weaker thrust, or a steeper thrust than basin free segments. The presence of basins is significant because they stabilize the margin and prevent subduction and accretion related deformation. This stabilization allows the thrust to preferentially support thermally induced, fluid overpressures and undergo fault healing thus increasing the likelihood of large coseismic slip within basin segments. While no historical earthquake data supporting this argument exists for Cascadia, such behavior has been observed in many margins (Song and Simons, 2003; Wells et al., 2003). It is reasonable to assume that large earthquakes in Cascadia will have the same association

  5. Significant melting of ice-wedges and formation of thermocirques on hill-slopes of thermokarst lakes in Central Yakutia (Siberia)

    Science.gov (United States)

    Séjourné, Antoine; Costard, François; Gargani, Julien; Fedorov, Alexander; Skorve, Johnny

    2013-04-01

    On Earth, permafrost containing a high ice volume (referred as ice-rich) are sensible to climate change, they have been regionally degraded (thermokarst) during the early Holocene climatic optimum forming numerous thermokarst lakes in Central Yakutia (eastern Siberia). Recent temperature increases in the Arctic and Subarctic have been significantly greater than global averages. The frequency and magnitude of terrain disturbances associated with thawing permafrost are increasing in these regions and are thought to intensify in the future. Therefore, understand how is the current development of thermokarst is a critical question. Here, we describe the significant melting of ice-wedges on slopes of thermokarst lakes that leads to formation of amphitheatrical hollows referred as thermocirques. The evolution of thermocirques in Central Yakutia has been little studied and analyzing their formation could help to understand the recent thermokarst in relation to climate change in Central Yakutia. We studied the thermocirques at two scales: (i) field surveys of different thermocirques in July 2009-2010 and October 2012 to examine the processes and origin of melting of ice-wedges and; (ii) photo-interpretation of time series of satellite images (KH-9 Hexagon images of 6-9 m/pixel and GeoEye images of 50 cm/pixel) to study the temporal evolution of thermocirques. The melting of ground-ice on the scarp of thermocirque triggers falls and small mud-flows that induce the retreat of the scarp parallel to itself. Based on field studies and on GeoEye image comparison, we show that their rate of retrogressive growth is 1-2 m/year. On the hill-slopes of lakes, the thermokarst could be initiated by different processes that lead to the uncover and then melting of ice-wedges: thermal erosion by the waves of the ice-rich bluff; active-layer detachment (a form of slope failure linked to detachment of the seasonally thawed upper ground); flowing of water on the slope (precipitation) or

  6. Brief communication "Ground failure and liquefaction phenomena triggered by the 20 May 2012 Emilia-Romagna (Northern Italy earthquake: case study of Sant'Agostino–San Carlo–Mirabello zone"

    Directory of Open Access Journals (Sweden)

    R. Caputo

    2012-10-01

    Full Text Available The basic aim of this study was to observe and report the earthquake-induced ground deformation of the MW = 6.1 Emilia-Romagna (Northern Italy event that occurred on the 20 May 2012. The event caused widespread structural damages in a large area of the Po Plain, while the most characteristic geological effects were ground failure, lateral spreading and liquefaction. This post-earthquake reconnaissance report focuses on secondary effects within the area between the villages of Sant'Agostino, San Carlo and Mirabello located along a former reach of the Reno River. Our field observations started just few hours after the main shock until the 28 May 2012.

  7. Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames.

    Directory of Open Access Journals (Sweden)

    Satoshi Yamaguchi

    Full Text Available Biomechanical effects of laterally wedged insoles are assessed by reduction in the knee adduction moment. However, the degree of reduction may vary depending on the reference frame with which it is calculated. The purpose of this study was to clarify the effect of reference frame on the reduction in the knee adduction moment by laterally wedged insoles.Twenty-nine healthy participants performed gait trials with a laterally wedged insole and with a flat insole as a control. The knee adduction moment, including the first and second peaks and the angular impulse, were calculated using four different reference frames: the femoral frame, tibial frame, laboratory frame and the Joint Coordinate System.There were significant effects of reference frame on the knee adduction moment first and second peaks (P < 0.001 for both variables, while the effect was not significant for the angular impulse (P = 0.84. No significant interaction between the gait condition and reference frame was found in either of the knee adduction moment variables (P = 0.99 for all variables, indicating that the effects of laterally wedged insole on the knee adduction moments were similar across the four reference frames. On the other hand, the average percent changes ranged from 9% to 16% for the first peak, from 16% to 18% for the second peak and from 17% to 21% for the angular impulse when using the different reference frames.The effects of laterally wedged insole on the reduction in the knee adduction moment were similar across the reference frames. On the other hand, Researchers need to recognize that when the percent change was used as the parameter of the efficacy of laterally wedged insole, the choice of reference frame may influence the interpretation of how laterally wedged insoles affect the knee adduction moment.

  8. Prediction of knee joint moment changes during walking in response to wedged insole interventions.

    Science.gov (United States)

    Lewinson, Ryan T; Stefanyshyn, Darren J

    2016-04-01

    Wedged insoles are prescribed for medial knee osteoarthritis to reduce the knee adduction moment; however, it is currently not possible to predict which patients will in fact experience reduced moments. The purpose of this study was to identify a simple method using two-dimensional data for predicting the expected change in knee adduction moments with wedged insoles. Knee adduction moments during walking were determined for healthy individuals (n = 15) and individuals with medial knee osteoarthritis (n = 19) while wearing their own shoe without an insole (control), with a 6-mm medial wedge and with a 6-mm lateral wedge. The percent changes relative to control were determined. Then, participants completed single-step trials with each footwear condition where only the changes in mediolateral positions of the knee joint center, shank center of mass, ankle joint center, and foot center of mass relative to control were determined. These variables were used as predictors in regression equations where the change in knee adduction moment during walking was the dependent variable. The change in mediolateral positions of the lower extremity during a single step significantly predicted the change in knee adduction moment during walking for the lateral wedge in both the healthy (R(2) = 0.72, p = 0.008) and knee osteoarthritis (R(2) = 0.52, p = 0.026) groups, and also for the medial wedge in both the healthy (R(2) = 0.67, p = 0.016) and knee osteoarthritis (R(2) = 0.54, p = 0.020) groups. The method of using mediolateral position data from a single-step movement to predict walking biomechanics was successful. These data are relatively simple to collect and analyze, offering the possibility for future incorporation into a wedge prediction system. © IMechE 2016.

  9. The effect of shoe design and lateral wedges on knee load and neuromuscular control in healthy subjects during walking

    DEFF Research Database (Denmark)

    Mølgaard, Carsten Møller; Kersting, Uwe G.

    2013-01-01

    design/type on the effectiveness of lateral wedging has not been investigated so far. The Purpose of the present study was to explore alterations in knee loading due to lateral foot wedges in three different shoes. Methods: Thirteen healthy participants with no history of knee pain were tested using...... three-dimensional gait analysis. Barefoot walking, walking in a running shoe, an Oxford-type leather shoe, and a rocker shoe were analysed. The shoes were tested both with and without a 10-degree full-length laterally wedged insole. Results: There were significant shoe wedge interactions on the first...... and second peak knee adduction moments. However, the variability of this moment between shoe designs was of similar magnitude as the effect of laterally wedged insoles. Only marginal changes in muscle activity for gastrocnemius when walking with the wedged Oxford shoe were revealed. Conclusion: Lateral...

  10. Geometry and kinematics of accretionary wedge faults inherited from the structure and rheology of the incoming sedimentary section; insights from 3D seismic reflection data

    Science.gov (United States)

    Bell, Rebecca; Orme, Haydn; Lenette, Kathryn; Jackson, Christopher; Fitch, Peter; Phillips, Thomas; Moore, Gregory

    2017-04-01

    Intra-wedge thrust faults represent important conduits for fluid flow in accretionary prisms, modulating pore fluid pressure, effective stress and, ultimately, the seismic hazard potential of convergent plate boundaries. Despite its importance, we know surprisingly little regarding the 3D geometry and kinematics of thrust networks in accretionary prisms, largely due to a lack of 3D seismic reflection data providing high-resolution, 3D images. To address this we here present observations from two subduction zones, the Nankai and Lesser Antilles margins, where 3D seismic and borehole data allow us to constrain the geometry and kinematics of intra-wedge fault networks and to thus shed light on the mechanisms responsible for their structural style variability. At the Muroto transect, Nankai margin we find that the style of protothrust zone deformation varies markedly along-strike over distances of only a few km. Using structural restoration and quantitative fault analysis, we reveal that in the northern part of the study area deformation occurred by buckle folding followed by faulting. Further south, intra-wedge faults nucleate above the décollement and propagate radially with no folding, resulting in variable connectivity between faults and the décollement. The seismic facies character of sediments immediately above the décollement varies along strike, with borehole data revealing that, in the north, where buckle folding dominates un-cemented Lower Shikoku Basin sediments overlie the décollement. In contrast, further south, Opal CT-cemented, and thus rigid Upper Shikoku Basin sediments overlie the décollement. We suggest these along-strike variations in diagenesis and thus rheology control the observed structural style variability. Near Barbados, at the Lesser Antilles margin, rough subducting plate relief is blanketed by up to 700 m of sediment. 3D seismic data reveal that basement relief is defined by linear normal fault blocks and volcanic ridges, and sub

  11. Total knee arthroplasty after failed high tibial osteotomy: a systematic review of open versus closed wedge osteotomy.

    Science.gov (United States)

    Han, Jae Hwi; Yang, Jae-Hyuk; Bhandare, Nikhl N; Suh, Dong Won; Lee, Jong Seong; Chang, Yong Suk; Yeom, Ji Woong; Nha, Kyung Wook

    2016-08-01

    Medial opening wedge high tibial osteotomy (HTO) has become increasingly popular as an alternative to lateral closing wedge osteotomy for the treatment of medial compartment knee osteoarthritis with varus deformity. The present systematic review was conducted to provide an objective analysis of total knee arthroplasty (TKA) outcomes following previous knee osteotomy (medial opening wedge vs. lateral closing wedge). A literature search of online databases (MEDLINE, EMBASE, Cochrane Library database) was made, in addition to manual search of major orthopaedic journals. The methodological quality of each of the studies was assessed on the Newcastle-Ottawa Scale and Effective Practice and Organization of Care. A total of ten studies were included in the review. There were eight studies with Level IV and two studies with Level III evidence. Eight studies reported clinical and radiologic scores. Comparative studies between TKA following medial opening and lateral closing wedge HTO did not demonstrate statistically significant clinical and radiologic differences. The revision rates were similar. However, more technical issues during TKA surgery after lateral closing wedge HTO were mentioned than the medial open wedge group. The quadriceps snip, tibial tubercle osteotomy, and lateral soft tissue release were more frequently needed in the lateral closing wedge HTO group. In addition, because of loss of proximal tibia bone geometry in the lateral closing wedge HTO group, concerns such as tibia stem impingement in the lateral tibial cortex was noted. The present systematic review suggests that TKA after medial opening and lateral closing wedge HTO showed similar performance. Clinical and radiologic outcome including revision rates did not statistically differ from included studies. However, there are more surgical technical concerns in TKA conversion from lateral closing wedge HTO than from the medial opening wedge HTO group. IV.

  12. Wedge filling and interface delocalization in finite Ising lattices with antisymmetric surface fields

    Science.gov (United States)

    Milchev, Andrey; Müller, M.; Binder, K.; Landau, D. P.

    2003-09-01

    Theoretical predictions by Parry et al. for wetting phenomena in a wedge geometry are tested by Monte Carlo simulations. Simple cubic L×L×Ly Ising lattices with nearest neighbor ferromagnetic exchange and four free L×Ly surfaces, at which antisymmetric surface fields ±Hs act, are studied for a wide range of linear dimensions (4⩽L⩽320, 30⩽Ly⩽1000), in an attempt to clarify finite size effects on the wedge filling transition in this “double-wedge” geometry. Interpreting the Ising model as a lattice gas, the problem is equivalent to a liquid-gas transition in a pore with quadratic cross section, where two walls favor the liquid and the other two walls favor the gas. For temperatures T below the bulk critical temperature Tc this boundary condition (where periodic boundary conditions are used in the y direction along the wedges) leads to the formation of two domains with oppositely oriented magnetization and separated by an interface. For L,Ly→∞ and T larger than the filling transition temperature Tf(Hs), this interface runs from the one wedge where the surface planes with a different sign of the surface field meet (on average) straight to the opposite wedge, so that the average magnetization of the system is zero. For Tinterface is bound either to the wedge where the two surfaces with field -Hs meet (then the total magnetization m of the system is positive) or to the opposite wedge (then minterface midpoint from the wedges is studied as T→Tf(Hs) from below, as is the corresponding behavior of the magnetization and its moments. We consider the variation of l0 for T>Tf(Hs) as a function of a bulk field and find that the associated exponents agree with theoretical predictions. The correlation length ξy in the y direction along the wedges is also studied, and we find no transition for finite L and Ly→∞. For L→∞ the prediction l0∝(Hsc-Hs)-1/4 is verified, where Hsc(T) is the inverse function of Tf(Hs) and ξy∝(Hsc-Hs)-3/4, respectively. We

  13. Study and evaluation of the Siemens virtual wedge factor: dosimetric monitor system and variable field effects

    Energy Technology Data Exchange (ETDEWEB)

    Sendon Rio, J R Sendon; Martinez, C Otero; GarcIa, M Sanchez; Busto, R Lobato; Vega, V Luna; Sueiro, J Mosquera; Camean, M Pombar [Servizo de Radiofisica e Proteccion Radioloxica, Complexo Hospitalario Universitario de Santiago de Compostela (CHUS), Santiago de Compostela (Spain)], E-mail: jose.ramon.sendon.del.rio@sergas.es

    2008-03-07

    In the year 1997 Siemens introduced the virtual wedge in its accelerators. The idea was that a dose profile similar to that of a physical wedge can be obtained by moving one of the accelerator jaws at a constant speed while the dose rate is changing. This work explores the observed behaviour of virtual wedge factors. A model is suggested which takes into account that at any point in time, when the jaw moves, the dose at a point of interest in the phantom is not only due to the direct beam. It also depends on the scattered radiation in the phantom, the head scatter and the behaviour of the monitoring system of the accelerator. Measurements are performed in a Siemens Primus accelerator and compared to the model predictions. It is shown that the model agrees reasonably well with measurements spanning a wide range of conditions. A strong dependence of virtual wedge factors on the dosimetric board has been confirmed and an explanation has been given on how the balance between different contributions is responsible for virtual wedge factors values.

  14. Analysis of bonded anisotropic wedges with interface crack under anti-plane shear loading

    Institute of Scientific and Technical Information of China (English)

    M.GHADIRI; A.R.SHAHANI

    2014-01-01

    The antiplane stress analysis of two anisotropic finite wedges with arbitrary radii and apex angles that are bonded together along a common edge is investigated. The wedge radial boundaries can be subjected to displacement-displacement boundary condi-tions, and the circular boundary of the wedge is free from any traction. The new finite complex transforms are employed to solve the problem. These finite complex transforms have complex analogies to both kinds of standard finite Mellin transforms. The traction free condition on the crack faces is expressed as a singular integral equation by using the exact analytical method. The explicit terms for the strength of singularity are extracted, showing the dependence of the order of the stress singularity on the wedge angle, material constants, and boundary conditions. A numerical method is used for solving the resul-tant singular integral equations. The displacement boundary condition may be a general term of the Taylor series expansion for the displacement prescribed on the radial edge of the wedge. Thus, the analysis of every kind of displacement boundary conditions can be obtained by the achieved results from the foregoing general displacement boundary condition. The obtained stress intensity factors (SIFs) at the crack tips are plotted and compared with those obtained by the finite element analysis (FEA).

  15. Enhanced dynamic wedge output factors for Varian 2300CD and the case for a reference database.

    Science.gov (United States)

    Njeh, Christopher F

    2015-09-08

    Dose inhomogeneity in treatment planning can be compensated using physical wedges. Enhanced dynamic wedges (EDW) were introduced by Varian to overcome some of the shortcomings of physical wedges. The objectives of this study were to measure EDW output factors for 6 MV and 20 MV photon energies for a Varian 2300CD. Secondly, to review the literature in terms of published enhanced dynamic wedge output factors (EDWOF) for different Varian models and thereby add credence to the case of the validity of reference databases. The enhanced dynamic wedge output factors were measured for the Varian 2300CD for both 6MV and 20 MV photon energies. Twelve papers with published EDWOF for different Varian linac models were found in the literature. Comparing our results with the published mean, we found an excellent agreement for 6 MV EDWOF, with the percentage differences ranging from 0.01% to 0.57%, with a mean of 0.03%. The coefficient of variation of published EDWOF ranged from 0.17% to 0.85% and 0.1% to 0.9% for the for 6 MV and 18 MV photon energies, respectively. This paper provides the first published EDWOF for 20 MV photon energy. In addition, we have provided the first compendium of EDWOFs for different Varian linac models. The consistency of value across models and institution provide further support that a standard dataset of basic photon and electron dosimetry could be established as a guide for future commissioning, beam modeling, and quality assurance purposes.

  16. Medial Closing-Wedge Distal Femoral Osteotomy for Genu Valgum With Lateral Compartment Disease.

    Science.gov (United States)

    Wylie, James D; Maak, Travis G

    2016-12-01

    Lateral compartment disease combined with valgus alignment can lead to progressive knee joint degeneration. In the symptomatic patient with isolated lateral compartment disease, a varus-producing distal femoral osteotomy can unload the diseased lateral compartment. This osteotomy may be combined with other cartilage or meniscal restorative techniques to optimize knee joint preservation and pain relief. The osteotomy can be performed with a medial closing-wedge or lateral opening-wedge technique. Both techniques have been reported to improve knee-related quality of life in patients with lateral compartment disease. Advantages of the medial closing-wedge technique are direct bone apposition leading to inherent stability of the construct, as well as reliable bony healing, and less hardware irritation. Advantages of the lateral opening-wedge technique are a single bony cut and therefore more of an ability to adjust correction intraoperatively. However, this technique requires bone grafting and has a high rate of hardware irritation or removal. We present a surgical technique for the medial closing-wedge distal femoral osteotomy using an anteromedial-distal femoral locking plate.

  17. Simulation of water entry of an elastic wedge using the FDS scheme and HCIB method

    Institute of Scientific and Technical Information of China (English)

    SHIN Sangmook; BAE Sung Yong

    2013-01-01

    The hydroelasticity of water entry of an elastic wedge is simulated using a code developed using the flux-difference splitting scheme for immiscible and incompressible fluids and the hybrid Cartesian/immersed boundary method.The free surface is regarded as a moving contact discontinuity and is captured without any additional treatment along the interface.Immersed boundary nodes are distributed inside a fluid domain based on the edges that cross an instantaneous body boundary.Dependent variables are reconstructed at each immersed boundary node with the help of an interpolation along a local normal line for providing a boundary condition for a discretized flow problem.A dynamic beam equation is used for modeling the elastic deformation of a wedge.The developed code is validated through comparisons with other experimental and computational results for a free-falling wedge.The effects of the elastic deformation of the wedge on the pressure fields and time histories of the impact force are investigated in relation to the stiffness and density of the structure.Grid independence test is carried out for the computed time history of the force acting on an elastic wedge.

  18. Measurement of photoneutron dose produced by wedge filters of a high energy linac using polycarbonate films.

    Science.gov (United States)

    Hashemi, Seyed Mehdi; Hashemi-Malayeri, Bijan; Raisali, Gholamreza; Shokrani, Parvaneh; Sharafi, Ali Akbar; Torkzadeh, Falamarz

    2008-05-01

    Radiotherapy represents the most widely spread technique to control and treat cancer. To increase the treatment efficiency, high energy linacs are used. However, applying high energy photon beams leads to a non-negligible dose of neutrons contaminating therapeutic beams. In addition, using conventional linacs necessitates applying wedge filters in some clinical conditions. However, there is not enough information on the effect of these filters on the photoneutrons produced. The aim of this study was to investigate the change of photoneutron dose equivalent due to the use of linac wedge filters. A high energy (18 MV) linear accelerator (Elekta SL 75/25) was studied. Polycarbonate films were used to measure the dose equivalent of photoneutrons. After electrochemical etching of the films, the neutron dose equivalent was calculated using Hp(10) factor, and its variation on the patient plane at 0, 5, 10, 50 and 100 cm from the center of the X-ray beam was determined. By increasing the distance from the center of the X-ray beam towards the periphery, the photoneutron dose equivalent decreased rapidly for the open and wedged fields. Increasing of the field size increased the photoneutron dose equivalent. The use of wedge filter increased the proportion of the neutron dose equivalent. The increase can be accounted for by the selective absorption of the high energy photons by the wedge filter.

  19. 寒冷地区某办公楼地源热泵空调系统运行分析%Operational analysis of ground-source heat pump air conditioning system for an office building in cold zone

    Institute of Scientific and Technical Information of China (English)

    郑晓娜

    2015-01-01

    Combined with the project,presents the test results of ground-source heat pump under the shallow geothermal condition.The soil thermal balance analysis results show that the soil temperature increases by 0.3 ℃ after a period of cooling and heating season on condition that heat released from ground-source heat pump units to soil is 1.425 TJ.The analysis of operational data shows that temperature differences of entering and leaving water of condensers or evaporators on operation condition are commonly smaller than those on design condition for ground-source heat pump units,resulting in higher energy consumption of pumps.Suggests to apply the control mode of constant temperature difference and variable frequency of pump.%结合寒冷地区某办公楼地源热泵项目,介绍了浅层地热地质条件的测试结果。土壤热平衡分析结果表明,如果地源热泵机组全年向岩土体排热量为1.425 TJ,经过一个制冷季和一个供暖季后,岩土体温度升高幅度为0.30℃。运行数据分析结果表明,地源热泵冷凝器与蒸发器进出口温差在运行过程中通常小于设计温差,造成水泵能耗偏高,建议采用定温差、水泵变频调节的控制方式。

  20. The Eocimmerian history of Central Iran: the accretionary wedge of Anarak

    Science.gov (United States)

    Malaspina, Nadia; Zanchi, Andrea; Berra, Fabrizio; Javadi, Hamid Reza; Koohpeyma, Meysam; Ghassemi, Mohammad R.; Sheikholeslami, Mohammad Reza; Bergomi, Maria; Tunesi, Annalisa; Zanchetta, Stefano

    2013-04-01

    The Anarak region of Central Iran is a key area for the understanding of the Late Palaeozoic to Triassic Cimmerian evolution of Iran. The Anarak Metamorphic Complex (AMC) forms an E-W trending mountain ridge, which separates the Triassic of Nakhlak to the north from a continuous non-metamorphic Palaeozoic to Mesozoic sedimentary succession to the south and was interpreted as an accretionary wedge active from Late Palaeozoic to Triassic times. The AMC is sharply cross-cut westward by the Upper Cretaceous "Coloured Melange", consisting of low- to medium- grade metamorphic rocks with tectonically intercalated slivers of serpentinite often associated to blue schists. The occurrence of this rock association in Central Iran poses several questions regarding its evolution and especially on the number of Cimmerian (Palaeotethys) sutures (single rather than multiple) between Eurasia and Iran. The AMC includes several subunits (Morghab, Chah Gorbeh, Patyar, Palhavand Gneiss, Lakh Marble and Doshak) which differ for composition and/or metamorphic evolution. Based on field observations, the Morghab and Chah Gorbeh units suggest a common deformation and a similar metamorphic history, characterised by three major folding events. The first two events developed pervasive axial plane foliations causing a complete transposition of the primary stratigraphic characters. Folding was accompanied by two main metamorphic events, the latter showing retrogression from possible medium to low grade conditions. During the third folding stage, large-scale plunging to vertical open folds were superposed on previous folds in the area north of the Kuh-e Chah Gorbeh, deforming the previous penetrative foliations. In this frame, the Palhavand Gneiss can be considered as part of the same metamorphic unit which escaped a more pervasive low grade retrogression. Concerning the Patyar unit, previous studies considered the Lakh Marble as the lagoonal sediments of an atoll. Field analyses indicate that the

  1. 'Grounded' Politics

    DEFF Research Database (Denmark)

    Schmidt, Garbi

    2012-01-01

    play within one particular neighbourhood: Nørrebro in the Danish capital, Copenhagen. The article introduces the concept of grounded politics to analyse how groups of Muslim immigrants in Nørrebro use the space, relationships and history of the neighbourhood for identity political statements....... The article further describes how national political debates over the Muslim presence in Denmark affect identity political manifestations within Nørrebro. By using Duncan Bell’s concept of mythscape (Bell, 2003), the article shows how some political actors idealize Nørrebro’s past to contest the present...

  2. Radon determination in ground water

    Energy Technology Data Exchange (ETDEWEB)

    Segovia A, N.; Bulbulian G, S

    1991-08-15

    Studies on natural radioactivity in ground water were started in Mexico in San Luis Potosi state followed by samplings from deep wells and springs in the states of Mexico and Michoacan. The samples were analyzed for solubilized and {sup 226} Ra- supported {sup 222} Rn. Some of them were also studied for {sup 234} U/ {sup 238} U activity ratio. In this paper we discuss the activities obtained and their relationship with the geologic characteristics of the studied zones. (Author)

  3. A fully integrated high-Q Whispering-Gallery Wedge Resonator

    CERN Document Server

    Ramiro-Manzano, F; Pavesi, L; Pucker, G; Ghulinyan, M

    2012-01-01

    Microresonator devices which posses ultra-high quality factors are essential for fundamental investigations and applications. Microsphere and microtoroid resonators support remarkably high Q's at optical frequencies, while planarity constrains preclude their integration into functional lightwave circuits. Conventional semiconductor processing can also be used to realize ultra-high-Q's with planar wedge-resonators. Still, their full integration with side-coupled dielectric waveguides remains an issue. Here we show the full monolithic integration of a wedge-resonator/waveguide vertically-coupled system on a silicon chip. In this approach the cavity and the waveguide lay in different planes. This permits to realize the shallow-angle wedge while the waveguide remains intact, allowing therefore to engineer a coupling of arbitrary strength between these two. The precise size-control and the robustness against post-processing operation due to its monolithic integration makes this system a prominent platform for indu...

  4. The synthesis and adsorption properties of some carbohydrate-terminated dendrimer wedges

    CERN Document Server

    Ainsworth, R L

    1997-01-01

    A range of dendritic molecules that are designed to bind to a cotton surface has been synthesised. The architecture of the molecules allows the location of various functional, property modifying units at the focus and the attachment of recognition groups at the periphery of a dendritic molecule with wedge topology. The synthesis and characterisation of dendrimer wedges up to the second generation using a divergent approach has been performed. These wedges are readily built up using a simple and efficient stepwise pathway from the central core, and surface recognising species are subsequently attached to the molecule utilising procedures developed in conjunction with Unilever Research Laboratories. Work has been carried out to assess their adsorption onto a cotton surface and the postulated adsorption mechanism is discussed.

  5. Open wedge metatarsal osteotomy versus crescentic osteotomy to correct severe hallux valgus deformity

    DEFF Research Database (Denmark)

    Wester, Jens Ulrik; Hamborg-Petersen, Ellen; Herold, Niels

    2016-01-01

    BACKGROUND: Different techniques of proximal osteotomies have been introduced to correct severe hallux valgus. The open wedge osteotomy is a newly introduced method for proximal osteotomy. The aim of this prospective randomized study was to compare the radiological and clinical results after...... operation for severe hallux valgus, comparing the open wedge osteotomy to the crescentic osteotomy which is our traditional treatment. METHODS: Forty-five patients with severe hallux valgus (hallux valgus angle >35̊, and intermetatarsal angle >15̊) were included in this study. The treatment was proximal...... open wedge osteotomy and fixation with plate (Hemax), group 1, or operation with proximal crescentic osteotomy and fixation with a 3mm cannulated screw, group 2. The mean age was 52 years (19-71). Forty-one females and four males were included. Clinical and radiological follow-ups were performed 4...

  6. Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

    Science.gov (United States)

    Castner, Raymond; Zaman, Khairul; Fagan, Amy; Heath, Christopher

    2014-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.

  7. Water Impact of Rigid Wedges in Two-Dimensional Fluid Flow

    Directory of Open Access Journals (Sweden)

    Sawan Shah

    2015-01-01

    Full Text Available A combined experimental and numerical investigation was conducted into impact of rigid wedges on water in two-dimensional fluid conditions. Drop test experiments were conducted involving symmetric rigid wedges of varying angle and mass impacted onto water. The kinematic behaviour of the wedge and water was characterised using high-speed video. Numerical models were analysed in LS-DYNA® that combined regions of Smoothed Particle Hydrodynamics particles and a Lagrangian element mesh. The analysis captured the majority of experimental results and trends, within the bounds of experimental variance. Further, the combined modelling technique presented a highly attractive combination of computational efficiency and accuracy, making it a suitable candidate for aircraft ditching investigations.

  8. A quantum hybrid with a thin antenna at the vertex of a wedge

    Energy Technology Data Exchange (ETDEWEB)

    Carlone, Raffaele, E-mail: raffaele.carlone@unina.it [Università “Federico II” di Napoli, Dipartimento di Matematica e Applicazioni “R. Caccioppoli”, MSA, via Cinthia, I-80126, Napoli (Italy); Posilicano, Andrea, E-mail: andrea.posilicano@uninsubria.it [DiSAT, Università dell' Insubria, via Valleggio 11, I-22100, Como (Italy)

    2017-03-26

    We study the spectrum, resonances and scattering matrix of a quantum Hamiltonian on a “hybrid surface” consisting of a half-line attached by its endpoint to the vertex of a concave planar wedge. At the boundary of the wedge, outside the vertex, homogeneous Dirichlet conditions are imposed. The system is tunable by varying the measure of the angle at the vertex. - Highlights: • Spectral characterization of a quantum Hamiltonian on “hybrid surface” consisting of a halfline attached to the vertex of a concave planar wedge. • The system is tunable by varying the measure of the angle at the vertex. • Relation between the conduction properties inside the hybrid and formation of resonances. • Easy generalization of the results to more complicated structures.

  9. Origin of a crustal splay fault and its relation to the seismogenic zone and underplating at the erosional north Ecuador-south Colombia oceanic margin

    Science.gov (United States)

    Collot, J.-Y.; Agudelo, W.; Ribodetti, A.; Marcaillou, B.

    2008-12-01

    Splay faults within accretionary complexes are commonly associated with the updip limit of the seismogenic zone. Prestack depth migration of a multichannel seismic line across the north Ecuador-south Colombia oceanic margin images a crustal splay fault that correlates with the seaward limit of the rupture zone of the 1958 (Mw 7.7) tsunamogenic subduction earthquake. The splay fault separates 5-6.6 km/s velocity, inner wedge basement rocks, which belong to the accreted Gorgona oceanic terrane, from 4 to 5 km/s velocity outer wedge rocks. The outer wedge is dominated by basal tectonic erosion. Despite a 3-km-thick trench fill, subduction of 2-km-high seamount prevented tectonic accretion and promotes basal tectonic erosion. The low-velocity and poorly reflective subduction channel that underlies the outer wedge is associated with the aseismic, décollement thrust. Subduction channel fluids are expected to migrate upward along splay faults and alter outer wedge rocks. Conversely, duplexes are interpreted to form from and above subducting sediment, at ˜14- to 15-km depths between the overlapping seismogenic part of the splay fault and the underlying aseismic décollement. Coeval basal erosion of the outer wedge and underplating beneath the apex of inner wedge control the margin mass budget, which comes out negative. Intraoceanic basement fossil listric normal faults and a rift zone inverted in a flower structure reflect the evolution of the Gorgona terrane from Cretaceous extension to likely Eocene oblique compression. The splay faults could have resulted from tectonic inversion of listric normal faults, thus showing how inherited structures may promote fluid flow across margin basement and control seismogenesis.

  10. Growth of the deposit wedge in the mountain reservoir

    Science.gov (United States)

    Chen, Y.; Song, G.

    2011-12-01

    The sedimentary problem of mountain reservoirs in Taiwan is getting serious year by year.Due to eroded sediments enter downstream reservoirs,the loss of sediment transport capacity may cause deposition of sediment in reservoirs.This phenomenon make problems to small mountain reservoirs.To realize the interaction between deposit wedges and mountain reservoirs,we selected Wushe reservoir which is situated in central Taiwan for a case study. Wushe reservoir is long and narrow.In recent years,most sediment is introduced during rain events that now accompany climate change are very important in sediment supply.In this thesis,we collected data of underwater landform and sub-bottom bedding information by using high resolution Multibeam Survey System(MBS) and seismic-reflection system.Up to now,we already had the bathymetric data for more than ten years,moreover,in 2010,we used 3.5kHz sub-bottom seismic profiler to analysis the sedimentary bedding situation in this area.These methods provide us accurate reservoir topography,sediment accumulation and the major ways of sediment transportation.The study purposes are as follows: First,according to the available underwater data for last ten years,we recognize the geomorphological characters of sedimentation as well as complete the mappings.Comparing to bathymetric images each year,we evaluate the carried ways of sediment.The flow water which enters this area transports along the thalweg,which in eastern reservoir.The range of water level variation cause alteration of sedimentary morphology,it also affects the scope of alluvial fan.The alluvial fan is located in the middle of the reservoir,the edge of it had moved forward 500 meters for last ten years.The annual mean of forward velocity was 50 meters,the elevation of fan edge also accelerated 10 meters per year.In a word,the large volume of the sedimentary delta is in Wushe reservoir now. Second,trying to clarify the composition of sedimentation and explain the sub

  11. Quantitative comparisons of analogue models of brittle wedge dynamics

    Science.gov (United States)

    Schreurs, Guido

    2010-05-01

    Analogue model experiments are widely used to gain insights into the evolution of geological structures. In this study, we present a direct comparison of experimental results of 14 analogue modelling laboratories using prescribed set-ups. A quantitative analysis of the results will document the variability among models and will allow an appraisal of reproducibility and limits of interpretation. This has direct implications for comparisons between structures in analogue models and natural field examples. All laboratories used the same frictional analogue materials (quartz and corundum sand) and prescribed model-building techniques (sieving and levelling). Although each laboratory used its own experimental apparatus, the same type of self-adhesive foil was used to cover the base and all the walls of the experimental apparatus in order to guarantee identical boundary conditions (i.e. identical shear stresses at the base and walls). Three experimental set-ups using only brittle frictional materials were examined. In each of the three set-ups the model was shortened by a vertical wall, which moved with respect to the fixed base and the three remaining sidewalls. The minimum width of the model (dimension parallel to mobile wall) was also prescribed. In the first experimental set-up, a quartz sand wedge with a surface slope of ˜20° was pushed by a mobile wall. All models conformed to the critical taper theory, maintained a stable surface slope and did not show internal deformation. In the next two experimental set-ups, a horizontal sand pack consisting of alternating quartz sand and corundum sand layers was shortened from one side by the mobile wall. In one of the set-ups a thin rigid sheet covered part of the model base and was attached to the mobile wall (i.e. a basal velocity discontinuity distant from the mobile wall). In the other set-up a basal rigid sheet was absent and the basal velocity discontinuity was located at the mobile wall. In both types of experiments

  12. Balloon occlusion versus wedged hepatic venography using iodinated contrast for targeting the portal vein during TIPS.

    Science.gov (United States)

    Caporossi, J-M; Vidal, V; Jacquier, A; Reyre, A; Flavian, A; Muller, C; Gaubert, J-Y; Bartoli, J-M; Moulin, G; Varoquaux, A

    2015-04-01

    To assess the efficacy, safety and gain in procedure time of the technique of balloon occlusion hepatic venography with iodinated contrast used to target the portal vein during TIPS. The technique is assessed versus wedged hepatic venography. Fifty-eight TIPS were prospectively included. The portal vein was located in 30 cases by the wedged hepatic venography (group 1) and in 28 cases by balloon occlusion hepatic venography (group 2). To compare both techniques a "portogram quality" score was defined using a 5 points scale. The time required to achieve portal puncture was also recorded. The complications of both procedures were assessed and classified in groups as intrahepatic hematoma or intraperitoneal hemorrhage. The right portal vein was visualized in a significantly higher number of patients using balloon than with wedged retrograde venography 71.3% (20/28) versus 13.3% (4/30) respectively (P=0.002). The quality score for the portogram was significantly higher for balloon hepatic venography 2.21 than for wedged hepatic venography 1.07 (P=0.002). The mean time required to puncture the portal vein was significantly shorter when the right branch of the portal vein was visualized 21 min versus 33.5 min (P=0.046). We recorded one intrahepatic hematoma (3.3%) and 4 intraperitoneal hemorrhage (13.3%) secondary to wedged hepatic venography. There were no complications with balloon occlusion hepatic venography (P=0.053). The use of balloon occlusion hepatic venography improves the quality of the retrograde portal venography to target the portal vein and decreases procedure time. The balloon technique is also burdened with fewer complications than the standard wedged hepatic venography. Copyright © 2014 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  13. Tectonic and gravity extensional collapses in overpressured cohesive and frictional wedges

    Science.gov (United States)

    Yuan, X. P.; Leroy, Y. M.; Maillot, B.

    2015-03-01

    Two modes of extensional collapse in a cohesive and frictional wedge of arbitrary topography, finite extent, and resting on an inclined weak décollement are examined by analytical means. The first mode consists of the gravitational collapse by the action of a half-graben, rooting on the décollement and pushing seaward the frontal part of the wedge. The second mode results from the tectonics extension at the back wall with a similar half-graben kinematics and the landward sliding of the rear part of the wedge. The predictions of the maximum strength theorem, equivalent to the kinematic approach of limit analysis and based on these two collapse mechanisms, not only match exactly the solutions of the critical Coulomb wedge theory, once properly amended, but generalizes them in several aspects: wedge of finite size, composed of cohesive material and of arbitrary topography. This generalization is advantageous to progress in our understanding of many laboratory experiments and field cases. For example, it is claimed from analytical results validated by experiments that the stability transition for a cohesive, triangular wedge occurs with the activation of the maximum length of the décollement. It is shown that the details of the topography, for the particular example of the Mejillones peninsula (North Chile) is, however, responsible for the selection of a short length-scale, dynamic instability corresponding to a frontal gravitational instability. A reasonable amount of cohesion is sufficient for the pressures proposed in the literature to correspond to a stability transition and not with a dynamically unstable state.

  14. Saltwater upconing zone of influence

    Science.gov (United States)

    Jakovovic, Danica; Werner, Adrian D.; de Louw, Perry G. B.; Post, Vincent E. A.; Morgan, Leanne K.

    2016-08-01

    In this study, we define and characterize the saltwater upconing zone of influence (SUZI). The SUZI is the region around a pumping well within which significant rise in the saltwater-freshwater interface occurs. While the zone of influence of a pumping well can be clearly defined in terms of hydraulics (e.g., drawdown), the SUZI has not been recognised and characterised, despite its importance for groundwater decision-making in coastal regions. We explore the SUZI under various conditions and compare common methods of investigation using both axisymmetric (1D and 2D vertical cross-section) and 3D simulations of saltwater upconing at the field scale, based on a combination of numerical and analytical approaches. The SUZI was found to be dependent on the relative magnitudes of pumping, regional flow, distance of the well from the coast, and position of the well above the interface, as expected. The three-dimensional coastal setting simulations revealed an asymmetric shape of the lateral extent of the SUZI, which is largest in the direction parallel to the coast. This occurs because the ocean and the inland extent of the seawater wedge limit the propagation of the SUZI perpendicular to the coast. Predictions of the SUZI using the Ghyben-Herzberg approximation, including cases where sloping interfaces occur (i.e., in contrast to the artificiality of horizontal interfaces used in axisymmetric approaches), provide reasonable first approximations of the SUZI. Numerical modelling of dispersive upconing in the 3D inclined interface case is influenced by practical limits to the model domain size and grid resolution. For example, the no-flow boundary condition at 1500 m from the pumping well elongates the SUZI in the direction parallel to the coast. This study extends previous concepts of well interference, which have previously been based on hydraulics only, by introducing the SUZI and characterising its extent, with consideration given to differences in commonly adopted

  15. Subduction erosion of forearc mantle wedge implicated in the genesis of the South Sandwich Island (SSI) arc: Evidence from boron isotope systematics

    Science.gov (United States)

    Tonarini, Sonia; Leeman, William P.; Leat, Phil T.

    2011-01-01

    The South Sandwich volcanic arc is sited on a young oceanic crust, erupts low-K tholeiitic rocks, is characterized by unexotic pelagic and volcanogenic sediments on the down-going slab, and simple tectonic setting, and is ideal for assessing element transport through subduction zones. As a means of quantifying processes attending transfer of subduction-related fluids from the slab to the mantle wedge, boron concentrations and isotopic compositions were determined for representative lavas from along the arc. The samples show variable fluid-mobile/fluid-immobile element ratios and high enrichments of B/Nb (2.7 to 55) and B/Zr (0.12 to 0.57), similar to those observed in western Pacific arcs. δ11B values are among the highest so far reported for mantle-derived lavas; these are highest in the central part of the arc (+ 15 to + 18‰) and decrease toward the southern and northern ends (+ 12 to + 14‰). δ11B is roughly positively correlated with B concentrations and with 87Sr/86Sr ratios, but poorly coupled with other fluid-mobile elements such as Rb, Ba, Sr and U. Peridotites dredged from the forearc trench also have high δ11B (ca. + 10‰) and elevated B contents (38-140 ppm). Incoming pelagic sediments sampled at ODP Site 701 display a wide range in δ11B (+ 5 to - 13‰; average = - 4.1‰), with negative values most common. The unusually high δ11B values inferred for the South Sandwich mantle wedge cannot easily be attributed to direct incorporation of subducting slab materials or fluids derived directly therefrom. Rather, the heavy B isotopic signature of the magma sources is more plausibly explained by ingress of fluids derived from subduction erosion of altered frontal arc mantle wedge materials similar to those in the Marianas forearc. We propose that multi-stage recycling of high-δ11B and high-B serpentinite (possibly embellished by arc crust and volcaniclastic sediments) can produce extremely 11B-rich fluids at slab depths beneath the volcanic arc

  16. Trace element features of hydrothermal and inherited igneous zircon grains in mantle wedge environment: A case study from the Myanmar jadeitite

    Science.gov (United States)

    Lei, Weiyan; Shi, Guanghai; Santosh, M.; Ng, Yinok; Liu, Yingxin; Wang, Jing; Xie, Gen; Ju, Yan

    2016-12-01

    Jadeitites are considered to crystallise in ultramafic rocks in the subduction channel presumably from the overlying mantle wedge, and therefore zircons from these rocks provide important insights into mantle wedge processes. Here we investigate hydrothermal zircon (Group II) formed within a subduction zone and compare these with the igneous zircon cores (Group I) from the Myanmar jadeitite. Previous U-Pb studies reported ages of Groups I and II zircons as 163 Ma, and 147 Ma respectively, and both show isotope signature of the depleted mantle. Group I zircons have much higher total concentrations of rare earth elements (REEs) (500-1945 ppm) than those of Group II zircon (112-307 ppm), and contains relatively higher abundance of Y, Nb, Ta, Ti, Th and U with higher (Sm/La)N ratios (25.3-501) and Ce-anomalies (8.04-140) but lower (Yb/Gd)N ratios (9.76-57.0) than those of the Group II ((Sm/La)N ratios = 2.12-32.2, Ce-anomalies = 1.63-19.6, (Yb/Gd)N ratios = 44.8-142). Hf concentrations are broadly similar in both Groups. The Group I zircons are considered to be magmatic and crystallised from H2O-rich basaltic melt at relatively high pressure in the mantle wedge, whereas the Group II zircon overgrowth took place through recrystallisation and precipitation with distinct dissolution of the Group I zircons. Variation in the concentration of trace elements in zircons from Groups I to II in the mantle wedge is related to an intra-oceanic subduction system in the presence of Na-rich hydrothermal fluids under high-pressure and low-temperature. The Ti-in-zircon thermometer yield a mean crystallisation temperature of 742 ± 141 °C for Group I zircons, whereas the Group II zircons yield 339 ± 33 °C. The two groups of zircons also provide insights into the probable protolith involved in formation of the Myanmar jadeitite.

  17. Comparison of infinite and wedge fringe settings in Mach Zehnder interferometer for temperature field measurement

    Energy Technology Data Exchange (ETDEWEB)

    Haridas, Divya [Department of Physics, National Institute of Technology Calicut, Kerala, 673601 (India); P, Vibin Antony; Sajith, V.; Sobhan, C. B. [School of Nano Science and Technology, National Institute of Technology Calicut, Kerala, 673601 (India)

    2014-10-15

    Interferometric method, which utilizes the interference of coherent light beams, is used to determine the temperature distribution in the vicinity of a vertical heater plate. The optical components are arranged so as to obtain wedge fringe and infinite fringe patterns and isotherms obtained in each case were compared. In wedge fringe setting, image processing techniques has been used for obtaining isotherms by digital subtraction of initial parallel fringe pattern from deformed fringe pattern. The experimental results obtained are compared with theoretical correlations. The merits and demerits of the fringe analysis techniques are discussed on the basis of the experimental results.

  18. Wedge filling and interface delocalization in finite Ising lattices with antisymmetric surface fields.

    Science.gov (United States)

    Milchev, Andrey; Müller, M; Binder, K; Landau, D P

    2003-09-01

    Theoretical predictions by Parry et al. for wetting phenomena in a wedge geometry are tested by Monte Carlo simulations. Simple cubic LxLxL(y) Ising lattices with nearest neighbor ferromagnetic exchange and four free LxL(y) surfaces, at which antisymmetric surface fields +/-H(s) act, are studied for a wide range of linear dimensions (4Ising model as a lattice gas, the problem is equivalent to a liquid-gas transition in a pore with quadratic cross section, where two walls favor the liquid and the other two walls favor the gas. For temperatures T below the bulk critical temperature T(c) this boundary condition (where periodic boundary conditions are used in the y direction along the wedges) leads to the formation of two domains with oppositely oriented magnetization and separated by an interface. For L,L(y)--> infinity and T larger than the filling transition temperature T(f)(H(s)), this interface runs from the one wedge where the surface planes with a different sign of the surface field meet (on average) straight to the opposite wedge, so that the average magnetization of the system is zero. For Tinterface is bound either to the wedge where the two surfaces with field -H(s) meet (then the total magnetization m of the system is positive) or to the opposite wedge (then minterface midpoint from the wedges is studied as T-->T(f)(H(s)) from below, as is the corresponding behavior of the magnetization and its moments. We consider the variation of l(0) for T>T(f)(H(s)) as a function of a bulk field and find that the associated exponents agree with theoretical predictions. The correlation length xi(y) in the y direction along the wedges is also studied, and we find no transition for finite L and L(y)--> infinity. For L--> infinity the prediction l(0) proportional, variant (H(sc)-H(s))(-1/4) is verified, where H(sc)(T) is the inverse function of T(f)(H(s)) and xi(y) proportional, variant (H(sc)-H(s))(-3/4), respectively. We also find that m vanishes discontinuously at the

  19. Molecular depth profiling with cluster secondary ion mass spectrometry and wedges.

    Science.gov (United States)

    Mao, Dan; Wucher, Andreas; Winograd, Nicholas

    2010-01-01

    Secondary ion mass spectrometry and atomic force microscopy are employed to characterize a wedge-shaped crater eroded by 40 keV C(60)(+) bombardment of a 395 nm thin film of Irganox 1010 doped with four delta layers of Irganox 3114. The wedge structure creates a laterally magnified cross section of the film. From an examination of the resulting surface, information about depth resolution, topography, and erosion rate can be obtained as a function of crater depth in a single experiment. This protocol provides a straightforward way to determine the parameters necessary to characterize molecular depth profiles and to obtain an accurate depth scale for erosion experiments.

  20. Global Solutions of Shock Reflection by Wedges for the Nonlinear Wave Equation

    Institute of Scientific and Technical Information of China (English)

    Xuemei DENG; Wei XIANG

    2011-01-01

    When a plane shock hits a wedge head on,it experiences a reflection-diffraction process and then a self-similar reflected shock moves outward as the original shock moves forward in time.In this paper,shock reflection by large-angle wedges for compressible flow modeled by the nonlinear wave equation is studied and a global theory of existence,stability and regularity is established.Moreover,C0,1 is the optimal regularity for the solutions across the degenerate sonic boundary.

  1. Laparoscopic wedge resection of synchronous gastric intraepithelial neoplasia and stromal tumor: a case report.

    Science.gov (United States)

    Mou, Yi-Ping; Xu, Xiao-Wu; Xie, Kun; Zhou, Wei; Zhou, Yu-Cheng; Chen, Ke

    2010-10-21

    Synchronous occurrence of epithelial neoplasia and gastrointestinal stromal tumor (GIST) in the stomach is uncommon. Only rare cases have been reported in the literature. We present here a 60-year-old female case of synchronous occurrence of gastric high-level intraepithelial neoplasia and GIST with the features of 22 similar cases and detailed information reported in the English-language literature summarized. In the present patient, epithelial neoplasia and GIST were removed en bloc by laparoscopic wedge resection. To the best of our knowledge, this is the first reported case treated by laparoscopic wedge resection.

  2. RESEARCH ON THE MOTION CHARACTERISTICS OF FIBER SUSPENSIONS IN A WEDGE-SHAPED FLOW

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper the motion of cylindrical particles in a wedge-shaped flow was studied. The velocity distribution of wedge-shaped flow was simulated first, then the Euler-Lagrange model used to calculate the motion of cylindrical particles. The evolution of particle location, velocity and orientation with time was examined. The trajectories of the particles with different particle Stokes number, rate of flow and initial particle orientation were drawn. The results indicate that the Stokes number and initial orientation are important parameters which affect the particle motion. The conclusions are helpful to the engineering applications.

  3. Reconstruction of Bulk Operators within the Entanglement Wedge in Gauge-Gravity Duality

    Science.gov (United States)

    Dong, Xi; Harlow, Daniel; Wall, Aron C.

    2016-07-01

    In this Letter we prove a simple theorem in quantum information theory, which implies that bulk operators in the anti-de Sitter/conformal field theory (AdS/CFT) correspondence can be reconstructed as CFT operators in a spatial subregion A , provided that they lie in its entanglement wedge. This is an improvement on existing reconstruction methods, which have at most succeeded in the smaller causal wedge. The proof is a combination of the recent work of Jafferis, Lewkowycz, Maldacena, and Suh on the quantum relative entropy of a CFT subregion with earlier ideas interpreting the correspondence as a quantum error correcting code.

  4. Bulk Reconstruction in the Entanglement Wedge in AdS/CFT

    CERN Document Server

    Dong, Xi; Wall, Aron C

    2016-01-01

    In this note we prove a simple theorem in quantum information theory, which implies that bulk operators in the Anti-de Sitter / Conformal Field Theory (AdS/CFT) correspondence can be reconstructed as CFT operators in a spatial subregion $A$, provided that they lie in its entanglement wedge. This is an improvement on existing reconstruction methods, which have at most succeeded in the smaller causal wedge. The proof is a combination of the recent work of Jafferis, Lewkowycz, Maldacena, and Suh on the quantum relative entropy of a CFT subregion with earlier ideas interpreting the correspondence as a quantum error correcting code.

  5. Post-LGM grounding line and calving front translations of the West Antarctic Ice Sheet in the Whales Deep paleo-ice-stream trough, eastern Ross Sea, Antarctica

    Science.gov (United States)

    McGlannan, A. J.; Bart, P. J.; Chow, J.

    2016-12-01

    A large-area (2500 km2) multibeam survey of the Whales Deep paleo-ice-stream trough, eastern Ross Sea, Antarctica was acquired during NBP1502B. This sector of the continental shelf is important as it was covered by grounded and floating ice, which drained the central part of an expanded West Antarctic Ice Sheet (WAIS) during the last glacial cycle. The seafloor geomorphology shows a well-defined cluster of four back stepping grounding zone wedges (GZWs) that were deposited in a partly overlapping fashion on the middle continental shelf during WAIS retreat. These observations permit two end-member possibilities for how the WAIS grounding line and calving front vacated the trough. In the first scenario, each GZW represents successive landward shifts of the grounding line and calving front. In the second scenario, each GZW represents a large-scale retreat and re-advance of grounded and floating ice. To determine which of these two end-member scenarios most accurately describes WAIS retreat from this sector of Ross Sea, we evaluated a grid of kasten and piston cores. The core stations were selected on the basis of backstepping GZWs along the trough axis. Our core data analyses included an integration of visual core descriptions, x-ray images, grain size, water content, total organic carbon, shear strengths, and diatom assemblage data. Core data reveal a single transgressive succession from proximal diamict overlain by sub-ice-shelf and/or open-marine sediments. These data strongly support the first scenario, suggesting that an ice shelf remained continuously intact during the time that the grounding line successively moved from the shelf edge to the middle shelf by small-scale landward translations until the end of the fourth grounding event. Sedimentologic and diatom-assemblage data from the inner shelf show that only the last middle shelf grounding event ended with a long-distance retreat of grounded and then floating ice to south of the modern calving front.

  6. The 4 January 2016 Manipur earthquake in the Indo-Burmese wedge, an intra-slab event

    Directory of Open Access Journals (Sweden)

    V. K. Gahalaut

    2016-09-01

    Full Text Available Earthquakes in the Indo-Burmese wedge occur due to India-Sunda plate motion. These earthquakes generally occur at depth between 25 and 150 km and define an eastward gently dipping seismicity trend surface that coincides with the Indian slab. Although this feature mimics the subduction zone, the relative motion of Indian plate predominantly towards north, earthquake focal mechanisms suggest that these earthquakes are of intra-slab type which occur on steep plane within the Indian plate. The relative motion between the India and Sunda plates is accommodated at the Churachandpur-Mao fault (CMF and Sagaing Fault. The 4 January 2016 Manipur earthquake (M 6.7 is one such earthquake which occurred 20 km west of the CMF at ∼60 km depth. Fortunately, this earthquake occurred in a very sparse population region with very traditional wooden frame houses and hence, the damage caused by the earthquake in the source region was very minimal. However, in the neighbouring Imphal valley, it caused some damage to the buildings and loss of eight lives. The damage in Imphal valley due to this and historical earthquakes in the region emphasizes the role of local site effect in the Imphal valley.

  7. Ground beetles of the Ukraine (Coleoptera, Carabidae).

    Science.gov (United States)

    Putchkov, Alexander

    2011-01-01

    A review of the ground beetles of the Ukrainian fauna is given. Almost 750 species from 117 genera of Carabidae are known to occur in the Ukraine. Approximately 450 species of ground beetles are registered in the Carpathian region. No less than 300 species of ground beetles are found in the forest zone. Approximately 400 species of Carabidae present in the forest-steppe zone are relatively similar in species composition to those in the forest territories. Some 450 species of Carabidae are inhabitants of the steppe zone. Representatives of many other regions of heterogeneous biotopes such as forest, semi desert, intrazonal, etc. can be found in the steppe areas. The fauna of Carabidae (ca. 100 species) of the lowlands of southern Ukraine (sandy biotopes), situated mostly in the Kherson region, is very peculiar. The fauna of the Crimean mountains contains about 300 species. Conservation measures for the Carabidae are discussed.

  8. Ground beetles of the Ukraine (Coleoptera, Carabidae

    Directory of Open Access Journals (Sweden)

    Alexander Putchkov

    2011-05-01

    Full Text Available A review of the ground beetles of the Ukrainian fauna is given. Almost 750 species from 117 genera of Carabidae are known to occur in the Ukraine. Approximately 450 species of ground beetles are registered in the Carpathian region. No less than 300 species of ground beetles are found in the forest zone. Approximately 400 species of Carabidae present in the forest-steppe zone are relatively similar in species composition to those in the forest territories. Some 450 species of Carabidae are inhabitants of the steppe zone. Representatives of many other regions of heterogeneous biotopes such as forest, semi desert, intrazonal, etc. can be found in the steppe areas. The fauna of Carabidae (ca. 100 species of the lowlands of southern Ukraine (sandy biotopes, situated mostly in the Kherson region, is very peculiar. The fauna of the Crimean mountains contains about 300 species. Conservation measures for the Carabidae are discussed.

  9. The effect of shoe design and lateral wedges on knee load and neuromuscular control in healthy subjects during walking

    DEFF Research Database (Denmark)

    Mølgaard, Carsten; Kersting, Uwe G.

    2014-01-01

    three-dimensional gait analysis. Barefoot walking, walking in a running shoe, an Oxford-type leather shoe, and a rocker shoe were analysed. The shoes were tested both with and without a 10-degree full-length laterally wedged insole. Results: There were significant shoe wedge interactions on the first...

  10. 76 FR 24856 - Heavy Forged Hand Tools (i.e., Axes & Adzes, Bars & Wedges, Hammers & Sledges, and Picks...

    Science.gov (United States)

    2011-05-03

    ..., and Picks & Mattocks) From the People's Republic of China: Final Results of the Expedited Sunset... & Adzes, Bars & Wedges, Hammers & Sledges, and Picks & Mattocks) from the People's Republic of China..., track tools and wedges; (3) picks and mattocks; and (4) axes, adzes and similar hewing tools. Hand...

  11. 76 FR 52313 - Heavy Forged Hand Tools (i.e., Axes & Adzes, Bars & Wedges, Hammers & Sledges, and Picks...

    Science.gov (United States)

    2011-08-22

    ..., and Picks & Mattocks) From the People's Republic of China: Continuation of Antidumping Duty Orders... & Adzes, Bars & Wedges, Hammers & Sledges, and Picks & Mattocks) (``Hand Tools'') from the People's... & Wedges, Hammers & Sledges, and Picks & Mattocks) From the People's Republic of China: Final Results...

  12. Determination of refractive index of a simple negative, positive, or zero power lens using wedged plated interferometer

    Science.gov (United States)

    Shukla, R. P.; Perera, G. M.; George, M. C.; Venkateswarlu, P.

    1990-01-01

    A nondestructive technique for measuring the refractive index of a negative lens using a wedged plate interferometer is described. The method can be also used for measuring the refractive index of convex or zero power lenses. Schematic diagrams are presented for the use of a wedged plate interferometer for measuring the refractive index of a concave lens and of a convex lens.

  13. The effects of various kinds of lateral wedge insoles on performance of individuals with knee joint osteoarthritis

    Directory of Open Access Journals (Sweden)

    Masoud Rafiaee

    2012-01-01

    Conclusion: Using lateral wedge insole is a simple, inexpensive therapy for decreasing pain and improving quality of life; however, most research must be carried out to find the effects of lateral wedge on severity of knee joint OA and aligning TFA.

  14. Commissioning Siemens Virtual Wedges in the Oncentra MasterPlan treatment planning system using Gafchromic EBT film.

    Science.gov (United States)

    Ferretti, A; Simonato, F; Zandonà, R; Reccanello, S; Fabbris, R

    2010-12-01

    Virtual Wedges were introduced in Siemens LINACs to improve the treatment workflow. The aim of the present work is the validation of dose calculation by MasterPlan-Oncentra treatment planning system for virtual wedged beams. The Oncor Siemens accelerator installed in the authors' department produces 6 and 15 MV photon beams. At first, the consistency of VW LINAC production was tested and the EBT film measuring method was verified. This method is based on the scanner uniformity correction and absolute dose calibration as reported in literature. Then, the measured and calculated wedge factors and beam profiles are compared. For 15 degrees, 30 degrees, 45 degrees, and 60 degrees wedge angles, the wedge factors for different field sizes were measured by an ionization chamber and the dose profiles were acquired by Gafchromic EBT film. Both types of measurements were collected in isocentric condition. The comparison between measured and calculated VW factors shows discrepancies that increase with field size and angle. The OTP Enhanced algorithm produces better agreement with measurements than the Classic one, with improvement overall visible for large angles. The agreement between measured and planned beam profiles is within limits reported by the ESTRO Booklet No. 7 in terms of confidence limits. The MasterPlan-Oncentra treatment planning system determines wedge factors and VW profiles within the requested accuracy in the majority of treatment conditions. For big field dimensions and wedge angle, wedge factor accordance was worse, but it may be increased with an improvement of the LINAC dosimetric board calibration.

  15. Accuracy and initial stability of open- and closed-wedge high tibial osteotomy: a cadaveric RSA study.

    NARCIS (Netherlands)

    Gaasbeek, R.D.A.; Welsing, R.T.C.; Verdonschot, N.J.J.; Rijnberg, W.J.; Loon, C.J.M. van; Kampen, A. van

    2005-01-01

    We analyzed the difference in angle-correction accuracy and initial stability between open-wedge (OWO) and closed-wedge tibial valgus osteotomy (CWO). Five fresh-frozen pairs of human cadaver lower limbs were used; their bone mineral density (BMD) was measured with DEXA and a planned 7 degrees valgu

  16. Investigation on the Combined Use of Ground Penetrating Radar, Cone Penetrometer and High Resolution Seismic Data for Near Surface and Vadose Zone Characterization in the A/M Area of the Savannah River Site, South Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Wyatt, D.E. [Westinghouse Savannah River Company, AIKEN, SC (United States); Cumbest, R.J.; Aadland, R.K.; Syms, F.H.; Stephenson, D.E.; Sherrill, J.C.

    1997-06-01

    This study compares data from Cone Penetrometer Tests (CPT), high resolution surface reflection seismic (HRS) data and ground penetrating radar (GPR) data in the upper 120 feet (40 meters) of the A/M Area, Upper Three Runs Watershed at the Savannah River Site in South Carolina. The CPT, GPR, and HRS data were obtained along the Silverton Road in the western sector of the A/M Area groundwater plume, and adjacent to Geophysical Correlation Boring {number_sign}1 (GCB-1). This location allows for multiple correlations to be made between the various data sources, and supports shallow investigations for near surface affects of the Crackerneck Fault, a major structural feature in the area. Borehole geophysical data from GCB-1 were used to provide subsurface constraints on the CPT, GPR, and HRS data. core data, natural gamma ray, spectral gamma data, multi-level induction resistivity, density and sonic data were utilized to distinguish clays, sands and silts. The CPT data provided tip bearing and sleeve stress, as an indicator of stratigraphy. Reflection seismic data provided continuous subsurface profiles of key marker horizons. Ground Penetrating Radar provided information on shallow subsurface geological features. Conclusions from this study suggest that there is a high degree of correlation between the CPT and borehole geophysical data, specifically, the Friction Ratio and gamma/spectral gamma curves. The Upland/Tobacco Road, Tobacco Road/Dry Branch, Dry Branch/Santee, Santee/Warley Hill and the Warley Hill/Congaree contacts are discernible. From these contacts it is possible to map structural relationships in the shallow subsurface that are tied to regional data. Because formation contacts are discernible, CPT, HRS, GPR, and geophysical log intra-formational anomalies are mappable. These features allow for stratigraphic and facies mapping using the GPR and HRS data for continuity and the CPT and geophysical data for lithofacies analysis. It is possible to use the

  17. Long range hybrid tube-wedge plasmonic waveguide with extreme light confinement and good fabrication error tolerance.

    Science.gov (United States)

    Ding, Li; Qin, Jin; Xu, Kai; Wang, Liang

    2016-02-22

    We studied a novel long range hybrid tube-wedge plasmonic (LRHTWP) waveguide consisting of a high index dielectric nanotube placed above a triangular metal wedge substrate. Using comprehensive numerical simulations on guiding properties of the designed waveguide, it is found that extreme light confinement and low propagation loss are obtained due to strong coupling between dielectric nanotube mode and wedge plasmon polariton. Comparing with previous studied hybrid plasmonic waveguides, the LRHTWP waveguide has longer propagation length and tighter mode confinement. In addition, the LRHTWP waveguide is quite tolerant to practical fabrication errors such as variation of the wedge tip angle and the horizontal misalignment between the nanotube and the metal wedge. The proposed LRHTWP waveguide could have many application potentials for various high performance nanophotonic components.

  18. The distribution and depth of ion doses implanted into wedges by plasma immersion ion implantation in drifting and stationary plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Tarrant, R N; Devasahayam, S; McKenzie, D R; Bilek, M M M [School of Physics (A28), University of Sydney, NSW 2006 (Australia)

    2006-08-15

    The distribution of ion dose arising from plasma immersion ion implantation (PIII) of a complex shape in the form of a wedge is measured. Two types of plasma are considered: a drifting titanium plasma derived from a pulsed cathodic arc and a stationary plasma generated by PIII pulses in oxygen or nitrogen gas. The distributions of the implanted material over the surface of the aluminium wedge were studied using secondary ion mass spectroscopy and Rutherford backscattering. The effects of varying the apex angles of the wedge and the plasma density are investigated. We conclude that ion-focusing effects at the apex of the wedge were more important for the drifting plasma than for the stationary plasmas. In a drifting plasma, the ion drift velocity directed towards the apex of the wedge compresses the sheath close to the apex and enhances the concentration of the dose. For the stationary plasma, the dose is more uniform.

  19. The Analysis on the Migration Law of Iron ions in the Ground Water within the Tongjiang River Protective Zone of Xiajiang Water Control Project%峡江水利枢纽同江河防护区地下水中铁离子运移规律分析

    Institute of Scientific and Technical Information of China (English)

    王呈辉; 李春华

    2015-01-01

    The overproof iron ionic concentration in the ground water which is used as the drinking water source is detrimental to residents' drinking water safety. Thus, studying its migration law could support the protection work of ground water which is used as the drinking water source. This paper aims to construct the iron ionic migration generalized model of ground water within the Tongjiang River protective zone so as to analyse the migration law of iron ions under the conditon that protective layers are installed or not between the Tongjiang protective zone and the reservoir area of Xiajiang Water Control Project . The results indicates that without protective layers, variation of iron ionic concentration appears to be a hook-like form of development with fast migration velocity and broad diffusion. Yet, with protective layers, variation appears to be a ligulate form with much slower speed and smaller diffusion range. Although the protective layers would effectively postpone the migration speed of iron ions and limit their migaration range, they could never solve the problem of iron ionic migration ultimately.%地下水铁离子浓度超标,将严重影响居民饮用水安全。认识地下水铁离子的运移规律,可为保护地下水饮用水源提供依据。本文基于溶质运移理论,建立同江河防护区内地下水铁离子运移概化模型,分析在同江河防护区与水库库区之间设置防护层与不设置防护层二种情况下铁离子的运移规律。分析表明,不设置防护层工况,铁离子浓度的变化呈现"钩状"形态发展,且运移速度快,扩散范围广;设置防护层工况,浓度的变化呈现“舌状”发展,运移速度、扩散范围远小于不设置防护层的情况;防护层会有效延缓铁的运移速度,限制运移范围,但不会从根本上解决铁的运移。

  20. Effects of two different degrees of lateral-wedge insoles on unilateral lower extremity load-bearing line in patients with medial knee osteoarthritis

    Directory of Open Access Journals (Sweden)

    Bilge Yılmaz

    2016-08-01

    Conclusion: Both wedge insoles was effective in moving of the unilateral lower extremity load carrying line to the lateral. Lateral wedged insoles are biomechanically effective and reduce loading of the medial compartment in patients with medial knee osteoarthritis.

  1. Analysis on electromagnetic scattering by a wedge with impedance faces under exact impedance boundary

    Institute of Scientific and Technical Information of China (English)

    吴良超; 汪茂光

    1995-01-01

    Under the exact impedance boundary condition (EIBC), by using wave equations and the longitudinal field method, the electromagnetic scattenng by an impedance wedge has been analysed in detail, following the Maliuzhinets approach, and the uniform diffraction coefficient of the diffracted field has been presented.

  2. Estimation of treatment efficacy with complier average causal effects (CACE) in a randomized stepped wedge trial.

    Science.gov (United States)

    Gruber, Joshua S; Arnold, Benjamin F; Reygadas, Fermin; Hubbard, Alan E; Colford, John M

    2014-05-01

    Complier average causal effects (CACE) estimate the impact of an intervention among treatment compliers in randomized trials. Methods used to estimate CACE have been outlined for parallel-arm trials (e.g., using an instrumental variables (IV) estimator) but not for other randomized study designs. Here, we propose a method for estimating CACE in randomized stepped wedge trials, where experimental units cross over from control conditions to intervention conditions in a randomized sequence. We illustrate the approach with a cluster-randomized drinking water trial conducted in rural Mexico from 2009 to 2011. Additionally, we evaluated the plausibility of assumptions required to estimate CACE using the IV approach, which are testable in stepped wedge trials but not in parallel-arm trials. We observed small increases in the magnitude of CACE risk differences compared with intention-to-treat estimates for drinking water contamination (risk difference (RD) = -22% (95% confidence interval (CI): -33, -11) vs. RD = -19% (95% CI: -26, -12)) and diarrhea (RD = -0.8% (95% CI: -2.1, 0.4) vs. RD = -0.1% (95% CI: -1.1, 0.9)). Assumptions required for IV analysis were probably violated. Stepped wedge trials allow investigators to estimate CACE with an approach that avoids the stronger assumptions required for CACE estimation in parallel-arm trials. Inclusion of CACE estimates in stepped wedge trials with imperfect compliance could enhance reporting and interpretation of the results of such trials.

  3. Nanoscale guiding for cold atoms based on surface plasmons along the tips of metallic wedges

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng-Ling; Tang Wei-Min; Zhou Ming; Gao Chuan-Yu

    2013-01-01

    We propose a novel scheme to guide neutral cold atoms in a nanoscale region based on surface plasmons (SPs) of one pair and two pairs of tips of metallic wedges with locally enhanced light intensity and sub-optical wavelength resolution.We analyze the near-field intensity distribution of the tip of the metallic wedge by the FDTD method,and study the total intensity as well as the total potential of optical potentials and van der Waals potentials for 87Rb atoms in the light field of one pair and two pairs of tips of metallic wedges.It shows that the total potentials of one pair and two pairs of tips of metallic wedges can generate a gravito-optical trap and a dark closed trap for nanoscale guiding of neutral cold atoms.Guided atoms can be cooled with efficient intensity-gradient Sisyphus cooling by blue-detuned light field.This provides an important step towards the generation of hybrid systems consisting of isolated atoms and solid devices.

  4. Numerical Simulation and Experimental Validation of an Integrated Sleeve-Wedge Anchorage for CFRP Rods

    DEFF Research Database (Denmark)

    Schmidt, Jacob Wittrup; Smith, Scott T.; Täljsten, Björn

    2011-01-01

    The tensioning of carbon fibre-reinforced polymer (CFRP) rods for prestressed concrete applications or post-tensioning repair and strengthening has met with mixed success. This is primarily due to limitations inherent in the use of traditional wedge anchors typically used for steel tendons. Recen...

  5. Impingement of water droplets on wedges and diamond airfoils at supersonic speeds

    Science.gov (United States)

    Serafini, John S

    1953-01-01

    An analytical solution has been obtained for the equations of motion of water droplets impinging on a wedge in a two-dimensional supersonic flow field with a shock wave attached to the wedge. The closed-form solution yields analytical expressions for the equation of the droplet trajectory, the local rate of impingement and the impingement velocity at any point on the wedge surface, and the total rate of impingement. The analytical expressions are utilized to determine the impingement on the forward surfaces of diamond airfoils in supersonic flow fields with attached shock waves. The results presented include the following conditions: droplet diameters from 2 to 100 microns, pressure altitudes from sea level to 30,000 feet, free-stream static temperatures from 420 degrees to 460 degrees R. Also, free-stream Mach numbers from 1.1 to 2.0, semi-apex angles for the wedge from 1.14 degrees to 7.97 degrees, thickness-to-chord ratios for the diamond airfoil from 0.02 to 0.14, chord lengths from 1 to 20 feet, and angles of attack from zero to the inverse tangent of the airfoil thickness-to-chord ratio.

  6. Optical necklaces generated by the diffraction on a stack of dielectric wedges

    Energy Technology Data Exchange (ETDEWEB)

    Izdebskaya, Yana [Nonlinear Physics Centre, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200 (Australia); Department of Physics, V.I. Vernandsky Taurida National University, Simferopol 95007, Crimea (Ukraine)], E-mail: yvi124@rsphysse.anu.edu.au

    2008-05-19

    We demonstrate that the regular ring-shaped arrays of Gaussian beams, or optical necklaces, can be generated using diffraction on a stack of dielectric wedges. A condition for self-similarity and structural stability of the beams has been derived and shows good comparison with experimental data.

  7. On the role of lateral waves in the radiation from the dielectric wedge

    DEFF Research Database (Denmark)

    Balling, Peter

    1973-01-01

    The field on the dielectric wedge is approximated by a plane-wave expansion as in [1]. Contributions from this solution to both the surface field and the radiation field are examined. Finally, an experimental radiation field is compared with the plane-wave solution and with a geometric-optical di...

  8. On the shape of a droplet in a wedge: new insight from electrowetting

    NARCIS (Netherlands)

    Baratian, D.; Cavalli, A.; Ende, van den H.T.M.; Mugele, F.

    2015-01-01

    The equilibrium morphology of liquid drops exposed to geometric constraints can be rather complex. Even for simple geometries, analytical solutions are scarce. Here, we investigate the equilibrium shape and position of liquid drops confined in the wedge between two solid surfaces at an angle α. Usin

  9. Quantitative planar Raman imaging through a spectrograph: visualisation of a supersonic wedge flow

    NARCIS (Netherlands)

    Tolboom, R.A.L.; Dam, N.J.; Meulen, J.J. ter; Bakker, P.G.

    2005-01-01

    Planar Raman imaging through a spectrograph is demonstrated as a diagnostic tool for quantitative flow visualisation of internal supersonic wedge flow. A dedicated Bayesian deconvolution filter is used to remove the spectral structure that is introduced by the spectrograph. The 2D density field is d

  10. Fossil predation: did some clavilithine fasciolariid gastropods employ valve-wedging to feed on bivalves?

    NARCIS (Netherlands)

    Vermeij, Geerat J.

    2015-01-01

    Several gastropods, including members of the Busyconinae, wedge or chip bivalve prey by inserting the outer lip between the valves. This habit, which is associated with an abapically downwardly convex outer lip, often results in breakage and subsequent repair of the lip. I tested the hypothesis that

  11. Thick-Walled Cylinder Theory Applied on a Conical Wedge Anchorage

    DEFF Research Database (Denmark)

    Bennitz, Anders; Grip, Niklas; Schmidt, Jacob Wittrup

    2011-01-01

    Conical wedge anchorages are frequently used to anchor steel tendons in prestressing applications within the construction industry. To replace the steel tendons with non-corrosive and low weight FRPs (Fiber Reinforced Polymers), the different mechanical interactions between the steel and FRPs call...

  12. Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw

    NARCIS (Netherlands)

    Vonk, J. E.; Mann, P. J.; Dowdy, K. L.; Davydova, A.; Davydov, S. P.; Zimov, N.; Spencer, R. G. M.; Bulygina, E. B.; Eglinton, T. I.; Holmes, R. M.

    2013-01-01

    Pleistocene Yedoma permafrost contains nearly a third of all organic matter (OM) stored in circum-arctic permafrost and is characterized by the presence of massive ice wedges. Due to its rapid formation by sediment accumulation and subsequent frozen storage, Yedoma OM is relatively well preserved an

  13. A reciprocating ledge technique in closing wedge osteotomy for genu valgum in adolescents.

    Science.gov (United States)

    Dhar, Shabir Ahmed; Butt, Mohammed Farooq; Mir, Mohammed Ramzan; Dar, Tahir Ahmed; Sultan, Asif

    2009-12-01

    To describe a technique that preserves anterior and posterior alternate ledges in a closing wedge osteotomy. Five patients aged 14 to 19 years underwent a closing wedge osteotomy for genu valgum in 8 limbs using a reciprocating ledge technique. A unicortical wedge of bone was removed, with the anterior and posterior cortices spared. The anterior cortex at the proximal level and the posterior cortex at the distal level were cut through. With a wobbling action, the osteotomy site was rotated, and the distal fragment externally rotated. Manual force was applied to close the osteotomy site ensuring overlapping of the reciprocal ledges. The distal fragment was translated laterally to prevent club deformity. The osteotomy site was held with one or 2 staples. Stability was tested by flexion and extension of knee. All 8 limbs attained bone union within 12 weeks, and full range of motion within a mean of 13 (range, 12-15) weeks. The mean correction of the tibiofemoral angle was 13 degrees. At a mean follow-up of 12 months, all patients were pain-free and none developed club deformity. Sparing reciprocal ledges in a closing wedge osteotomy for genu valgum may increase stability in the flexion-extension axis, enable early range-of-motion exercises, and facilitate early bone union.

  14. Laterally wedged insoles in knee osteoarthritis: do biomechanical effects decline after one month of wear?

    Directory of Open Access Journals (Sweden)

    Bennell Kim L

    2009-11-01

    Full Text Available Abstract Objective This study aimed to determine whether the effect of laterally wedged insoles on the adduction moment in knee osteoarthritis (OA declined after one month of wear, and whether higher reported use of insoles was associated with a reduced effect on the adduction moment at one month. Methods Twenty people with medial compartment OA underwent gait analysis in their own shoes wearing i no insoles and; ii insoles wedged laterally 5° in random order. Testing occurred at baseline and after one month of use of the insoles. Participants recorded daily use of insoles in a log-book. Outcomes were the first and second peak external knee adduction moment and the adduction angular impulse, compared across conditions and time with repeated measures general linear models. Correlations were obtained between total insole use and change in gait parameters with used insoles at one month, and change scores were compared between high and low users of insoles using general linear models. Results There was a significant main effect for condition, whereby insoles significantly reduced the adduction moment (all p Conclusion Effects of laterally wedged insoles on the adduction moment do not appear to decline after one month of continuous use, suggesting that significant wedge degradation does not occur over the short-term.

  15. A Novel Continuous Extrusion Process to Fabricate Wedge-Shaped Light Guide Plates

    Directory of Open Access Journals (Sweden)

    Wen-Tse Hsiao

    2013-01-01

    Full Text Available Backlight modules are key components in thin-film transistor liquid crystal displays (TFT-LCD. Among the components of a backlight module, the light guide plate (LGP plays the most important role controlling the light projected to the eyes of users. A wedge-shaped LGP, with its asymmetrical structure, is usually fabricated by an injection proces, but the fabrication time of this process is long. This study proposes a continuous extrusion process to fabricate wedge-shaped LGPs. This continuous process has advantages for mass production. Besides a T-die and rollers, this system also has an in situ monitor of the melt-bank that forms during the extrusion process, helping control the plate thickness. Results show that the melt bank has a close relationship with the plate thickness. The temperature of the bottom heater and roller was adjusted to reduce the surface deformation of the wedge-shaped plate. This continuous extrusion system can successfully manufacture wedge-shaped LGPs for mass production.

  16. Zoning Districts, Zoning, Published in 2002, Freelance.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Zoning Districts dataset, was produced all or in part from Hardcopy Maps information as of 2002. It is described as 'Zoning'. Data by this publisher are often...

  17. Some Historical Treatments should not be Forgotten: A Review of Cast Wedging and A Trick to Normalize Non-Standardized Digital X-rays

    OpenAIRE

    2014-01-01

    Introduction: Cast wedging is a simple and reproducible method of manipulating a sub-optimally reduced fracture producing a correction and a final alignment that is amenable to definitive closed treatment. Multiple successful techniques have been previously described in the literature (opening wedge, closing wedge and combination). Technical Note: We present a simple reproducible method of templating and executing a proper cast wedging technique using digital imaging systems that are not cont...

  18. Crustal and Fault Strengths from Critical Taper Measurements: Insights into the behavior of Accretionary Wedges using Distinct-Element Models

    Science.gov (United States)

    Strayer, L.; Suppe, J.

    2012-12-01

    It is increasingly clear that many major faults are weak relative to quasistatic friction because of dynamical effects involving the microprocesses of high-velocity friction and the energetics of large-scale fault rupture. Even at the toes of accretionary wedges where velocity strengthening is expected, large displacements can occur dynamically. We seek to better understand the relationship between the large-scale strength of such faults and of the crust containing them over a timescale much greater than seismic cycles. Critical-taper theory provides straightforward quantitative relationships between accretionary wedge geometry and absolute basal fault and wedge strengths with minimal assumptions. Wedge tapers constrain the far-field stresses under which detachments slip and wedges grow during wedge-growing events, whether they are dynamical or quasistatic. To date most applications of wedge mechanics to accretionary wedges involve analog and numerical modeling with largely conceptual insight, for example illuminating the role of geological heterogeneity. Here we demonstrate that recent theoretical advances that are successful in extracting absolute wedge and detachment strengths from the geometry of active wedges can also be applied to extract large-scale strengths in distinct element numerical models in both mechanically homogeneous and heterogeneous wedges. The distinct element method (DEM) is an ideal tool for the study and modeling of critical taper wedges: model wedges can be initially cohesive (bonded) or cohesionless. Faults and folds form naturally as the result of progressive bond breakage during shortening and wedge growth. Heterogeneity can be introduced by creating layered groups of particles of differing mechanical properties. The DEM suffers to some extent in that macro material properties cannot be directly prescribed but rather must be defined by a modest number of micro-properties and the process in necessarily iterative and developing a wide

  19. Phase transitions and interface fluctuations in double wedges and bi-pyramids with competing surface fields

    Science.gov (United States)

    Müller, M.; Milchev, A.; Binder, K.; Landau, D. P.

    2008-08-01

    The interplay between surface and interface effects on binary AB mixtures that are confined in unconventional geometries is investigated by Monte Carlo simulations and phenomenological considerations. Both double-wedge and bi-pyramid confinements are considered and competing surface fields are applied at the two opposing halves of the system. Below the bulk critical temperature, domains of opposite order parameter are stabilized at the corresponding corners and an interface runs across the middle of the bi-partite geometry. Upon decreasing the temperature further one encounters a phase transition at which the AB symmetry is broken. The interface is localized in one of the two wedges or pyramids, respectively, and the order parameter is finite. In both cases, the transition becomes discontinuous in the thermodynamic limit but it is not a first-order phase transition. In an antisymmetric double wedge geometry the transition is closely related to the wedge-filling transition. Choosing the ratio of the cross-section L × L of the wedge and its length L y according to L y / L 3 = const., simulations and phenomenological consideration show that the new type of phase transition is characterized by critical exponents α = 3/4, β = 0, and γ = 5/4 for the specific heat, order parameter, and susceptibility, respectively. In an antisymmetric bi-pyramid the transition occurs at the cone-filling transition of a single pyramid. The important critical fluctuations are associated with the uniform translation of the interface and they can be described by a Landau-type free energy. Monte Carlo results provide evidence that the coefficients of this Landau-type free energy exhibit a system-size dependence, which gives rise to critical amplitudes that diverge with system size and result in a transition that becomes discontinuous in the thermodynamic limit.

  20. Complex interactions between diapirs and 4-D subduction driven mantle wedge circulation.

    Science.gov (United States)

    Sylvia, R. T.; Kincaid, C. R.

    2015-12-01

    Analogue laboratory experiments generate 4-D flow of mantle wedge fluid and capture the evolution of buoyant mesoscale diapirs. The mantle is modeled with viscous glucose syrup with an Arrhenius type temperature dependent viscosity. To characterize diapir evolution we experiment with a variety of fluids injected from multiple point sources. Diapirs interact with kinematically induced flow fields forced by subducting plate motions replicating a range of styles observed in dynamic subduction models (e.g., rollback, steepening, gaps). Data is collected using high definition timelapse photography and quantified using image velocimetry techniques. While many studies assume direct vertical connections between the volcanic arc and the deeper mantle source region, our experiments demonstrate the difficulty of creating near vertical conduits. Results highlight extreme curvature of diapir rise paths. Trench-normal deflection occurs as diapirs are advected downward away from the trench before ascending into wedge apex directed return flow. Trench parallel deflections up to 75% of trench length are seen in all cases, exacerbated by complex geometry and rollback motion. Interdiapir interaction is also important; upwellings with similar trajectory coalesce and rapidly accelerate. Moreover, we observe a new mode of interaction whereby recycled diapir material is drawn down along the slab surface and then initiates rapid fluid migration updip along the slab-wedge interface. Variability in trajectory and residence time leads to complex petrologic inferences. Material from disparate source regions can surface at the same location, mix in the wedge, or become fully entrained in creeping flow adding heterogeneity to the mantle. Active diapirism or any other vertical fluid flux mechanism employing rheological weakening lowers viscosity in the recycling mantle wedge affecting both solid and fluid flow characteristics. Many interesting and insightful results have been presented based

  1. Petrology of HP/LT metapelitic rocks of an accretionary wedge, the Central Pontides, Turkey: evidence for tectonic stacking and syn-subduction exhumation

    Science.gov (United States)

    Aygül, Mesut; Okay, Aral; Oberhänsli, Roland

    2015-04-01

    Cretaceous HP/LT chloritoid-bearing metapelitic rocks crop out widely in the central part of the Pontides, northern Turkey. They are associated with eclogite to blueschist-facies metabasites and represent deep levels of an underplated subduction-accretion complex, which is tectonically overlain by low-grade HP phyllite/metasandstone intercalation along an extensional shear zone. Close to the shear zone, the footwall micaschists consist of quartz, phengite, paragonite, chlorite, rutile with syn-kinematic albite porphyroblast formed by pervasive shearing during exhumation. This type of micaschists is tourmaline-bearing and their retrograde nature suggests high-fluid flux along shear zones. Peak metamorphic assemblages are partly preserved in the chloritoid-micaschist farther away from the shear zone. Three peak metamorphic assemblages are identified and their PT conditions are constrained by pseudosections produced by Theriak-Domino and by Raman spectra of carbonaceous material: 1) garnet-chloritoid-glaucophane with lawsonite pseudomorphs (P: 17.5 ± 1 Kbar, T: 390-450 °C) 2) chloritoid with glaucophane pseudomorphs (P: 16-18 Kbar, T: 475 ± 40 °C) and 3) relatively high-Mg chloritoid (17%) with jadeite pseudomorphs (22-25 Kbar; T: 440 ± 30 °C) in addition to phengite, paragonite, quartz, chlorite, rutile. The last mineral assemblage is interpreted as transformation of the chloritoid + glaucophane assemblage to chloritoid + jadeite paragenesis with increasing pressure. Absence of tourmaline suggests that the chloritoid-micaschist did not interact with B-rich fluids during zero strain exhumation. Peak metamorphic assemblages and PT estimates suggest tectonic stacking within wedge with different depths of burial. 40Ar/39Ar phengite age of a pervasively sheared footwall micaschist is constrained to 100.6 ± 1.3 Ma and that of a chloritoid-micaschist is constrained to 91.8 ± 1.8 Ma suggesting exhumation during on-going subduction. Coupling and exhumation of the

  2. Stable isotope and gas properties of two ice wedges from Cape Mamontov Klyk, Laptev Sea, Northern Siberia

    Directory of Open Access Journals (Sweden)

    T. Boereboom

    2011-12-01

    Full Text Available This paper presents and discusses the texture, fabric and gas properties (contents of total gas, O2, N2, CO2, and CH4 of two ice wedges from Cape Mamontov Klyk, Laptev Sea, Northern Siberia. The two ice wedges display contrasting structures: one being of relatively "clean" ice and the other showing clean ice at its centre as well as debris-rich ice on its sides (referred to as ice-sand wedge. A comparison of gas properties, crystal size, fabrics and stable isotope data (δ18O and δD allows discriminating between three different facies of ice with specific paleoenvironmental signatures, suggesting different climatic conditions and rates of biological activity. More specifically, total gas content and composition reveal variable intensities of meltwater infiltration and show the impact of biological processes with contrasting contributions from anaerobic and aerobic conditions. Stable isotope data are shown to be valid for discussing changes in paleoenvironmental conditions and/or decipher different sources for the snow feeding into the ice wedges with time. Our data also give support to the previous assumption that the composite ice wedge was formed in Pleistocene and the ice wedge in Holocene times. This study sheds more light on the conditions of ice wedge growth under changing environmental conditions.

  3. Orthotic Heel Wedges Do Not Alter Hindfoot Kinematics and Achilles Tendon Force During Level and Inclined Walking in Healthy Individuals.

    Science.gov (United States)

    Weinert-Aplin, Robert A; Bull, Anthony M J; McGregor, Alison H

    2016-04-01

    Conservative treatments such as in-shoe orthotic heel wedges to treat musculoskeletal injuries are not new. However, weak evidence supporting their use in the management of Achilles tendonitis suggests the mechanism by which these heel wedges works remains poorly understood. It was the aim of this study to test the underlying hypothesis that heel wedges can reduce Achilles tendon load. A musculoskeletal modeling approach was used to quantify changes in lower limb mechanics when walking due to the introduction of 12-mm orthotic heel wedges. Nineteen healthy volunteers walked on an inclinable walkway while optical motion, force plate, and plantar pressure data were recorded. Walking with heel wedges increased ankle dorsiflexion moments and reduced plantar flexion moments; this resulted in increased peak ankle dorsiflexor muscle forces during early stance and reduced tibialis posterior and toe flexor muscle forces during late stance. Heel wedges did not reduce overall Achilles tendon force during any walking condition, but did redistribute load from the medial to lateral triceps surae during inclined walking. These results add to the body of clinical evidence confirming that heel wedges do not reduce Achilles tendon load and our findings provide an explanation as to why this may be the case.

  4. Differential wedging of vertebral body and intervertebral disc in thoracic and lumbar spine in adolescent idiopathic scoliosis – A cross sectional study in 150 patients

    Directory of Open Access Journals (Sweden)

    Kim Hak-Jun

    2008-08-01

    Full Text Available Abstract Background Hueter-Volkmann's law regarding growth modulation suggests that increased pressure on the end plate of bone retards the growth (Hueter and conversely, reduced pressure accelerates the growth (Volkmann. Literature described the same principle in Rat-tail model. Human spine and its deformity i.e. scoliosis has also same kind of pattern during the growth period which causes wedging in disc or vertebral body. Methods This cross sectional study in 150 patients of adolescent idiopathic scoliosis was done to evaluate vertebral body and disc wedging in scoliosis and to compare the extent of differential wedging of body and disc, in thoracic and lumbar area. We measured wedging of vertebral bodies and discs, along with two adjacent vertebrae and disc, above and below the apex and evaluated them according to severity of curve (curve 30° to find the relationship of vertebral body or disc wedging with scoliosis in thoracic and lumbar spine. We also compared the wedging and rotations of vertebrae. Results In both thoracic and lumbar curves, we found that greater the degree of scoliosis, greater the wedging in both disc and body and the degree of wedging was more at apex supporting the theory of growth retardation in stress concentration area. However, the degree of wedging in vertebral body is more than the disc in thoracic spine while the wedging was more in disc than body in lumbar spine. On comparing the wedging with the rotation, we did not find any significant relationship suggesting that it has no relation with rotation. Conclusion From our study, we can conclude that wedging in disc and body are increasing with progression on scoliosis and maximum at apex; however there is differential wedging of body and disc, in thoracic and lumbar area, that is vertebral body wedging is more profound in thoracic area while disc wedging is more profound in lumbar area which possibly form 'vicious cycle' by asymmetric loading to spine for the

  5. Hydrodynamic controls on oxygen dynamics in a riverine salt wedge estuary, the Yarra River estuary, Australia

    Science.gov (United States)

    Bruce, L. C.; Cook, P. L. M.; Teakle, I.; Hipsey, M. R.

    2014-04-01

    Oxygen depletion in coastal and estuarine waters has been increasing rapidly around the globe over the past several decades, leading to decline in water quality and ecological health. In this study we apply a numerical model to understand how salt wedge dynamics, changes in river flow and temperature together control oxygen depletion in a micro-tidal riverine estuary, the Yarra River estuary, Australia. Coupled physical-biogeochemical models have been previously applied to study how hydrodynamics impact upon seasonal hypoxia; however, their application to relatively shallow, narrow riverine estuaries with highly transient patterns of river inputs and sporadic periods of oxygen depletion has remained challenging, largely due to difficulty in accurately simulating salt wedge dynamics in morphologically complex areas. In this study we overcome this issue through application of a flexible mesh 3-D hydrodynamic-biogeochemical model in order to predict the extent of salt wedge intrusion and consequent patterns of oxygen depletion. The extent of the salt wedge responded quickly to the sporadic riverine flows, with the strength of stratification and vertical density gradients heavily influenced by morphological features corresponding to shallow points in regions of tight curvature ("horseshoe" bends). The spatiotemporal patterns of stratification led to the emergence of two "hot spots" of anoxia, the first downstream of a shallow region of tight curvature and the second downstream of a sill. Whilst these areas corresponded to regions of intense stratification, it was found that antecedent conditions related to the placement of the salt wedge played a major role in the recovery of anoxic regions following episodic high flow events. Furthermore, whilst a threshold salt wedge intrusion was a requirement for oxygen depletion, analysis of the results allowed us to quantify the effect of temperature in determining the overall severity and extent of hypoxia and anoxia. Climate

  6. Subsurface Thermal Erosion Of Ice-Wedge Polygon Terrains: Implications For Arctic Geosystem In Transition

    Science.gov (United States)

    Fortier, D.; Godin, E.; Lévesque, E.; Veillette, A.

    2014-12-01

    Subsurface thermal erosion is triggered by convective heat transfers between flowing water and permafrost. For inland ice-wedge polygon terrains, heat advection due to infiltration of run-off in the massive ice wedges and the ice-rich upper portion of permafrost creates sink holes and networks of interconnected tunnels in the permafrost. Mass movements such as collapse of tunnel's roof, retrogressive thaw-slumping along exposed permafrost and active layer detachment slides lead to the development of extensive gully networks in the landscape. These gullies drastically change the hydrology of ice-wedge polygon terrains and the fluxes of heat, water, sediment and carbon within the permafrost geosystem. Exportation of sediments by fluvial processes within gullies are positive mechanical feed-back effects that keep gully channels active over decades. Along gully margins, drainage of disturbed polygons and ponds, slope drainage, soil consolidation, plant colonization of disturbed gully slopes and wet to mesic plant succession of drained polygons change the thermal properties of the active layer and create negative feedback effects that stabilize active erosion processes and promote permafrost recovery in gully slopes and adjacent disturbed polygons. On Bylot Island (Nunavut), over 40 gullies were mapped and monitored to characterize gully geomorphology, thermal and mechanical processes of gully erosion, rates of gully erosion over time within different sedimentary deposits, total volume of eroded permafrost at the landscape scale and gully hydrology. We conducted field and laboratory experiments to quantify heat convection processes and speed of ice wedge ablation in order to derive empirical equations to develop a numerical, fully-coupled, heat and mass (water) transfer model of ice-wedge thermal erosion. We used data collected over 10 years of geomorphological gully monitoring, regional climate scenarios, our physics-based numerical thermal erosion model and our field

  7. Some Historical Treatments should not be Forgotten: A Review of Cast Wedging and A Trick to Normalize Non-Standardized Digital X-rays

    Science.gov (United States)

    Jacobson, Nathan A.; Lee, Christopher L.

    2014-01-01

    Introduction: Cast wedging is a simple and reproducible method of manipulating a sub-optimally reduced fracture producing a correction and a final alignment that is amenable to definitive closed treatment. Multiple successful techniques have been previously described in the literature (opening wedge, closing wedge and combination). Technical Note: We present a simple reproducible method of templating and executing a proper cast wedging technique using digital imaging systems that are not controlled for magnification with an illustrative case. Conclusion: Renewed interest in cast wedging can provide a cost effective treatment with proven clinical outcomes in an ever changing and uncertain reimbursement climate. PMID:27298956

  8. Ground-water flow related to streamflow and water quality

    Science.gov (United States)

    Van Voast, W. A.; Novitzki, R.P.

    1968-01-01

    A ground-water flow system in southwestern Minnesota illustrates water movement between geologic units and between the land surface and the subsurface. The flow patterns indicate numerous zones of ground-water recharge and discharge controlled by topography, varying thicknesses of geologic units, variation in permeabilities, and the configuration of the basement rock surface. Variations in streamflow along a reach of the Yellow Medicine River agree with the subsurface flow system. Increases and decreases in runoff per square mile correspond, apparently, to ground-water discharge and recharge zones. Ground-water quality variations between calcium sulfate waters typical of the Quaternary drift and sodium chloride waters typical of the Cretaceous rocks are caused by mixing of the two water types. The zones of mixing are in agreement with ground-water flow patterns along the hydrologic section.

  9. Magma Generation and Transport in Subduction Zones: Numerical Simulations of Chemical, Thermal and Mechanical Coupling During Magma Ascent by Porous Flow

    Science.gov (United States)

    Arcay, D.; Gerya, T.; Tackley, P.

    2007-12-01

    Most subduction zones are characterized by significant magmatic activity responsible for building trench-parallel volcanic arcs above descending slabs. High magma production rates observed within the arcs result from infiltration of water-rich fluids released by slab dehydration. The released water triggers hydrous melting of hot mantle wedges located above the cold slabs. However, the process of magma transport from the melt generation region located above the hydrated slab surface at 100-300 km depth to the magma extraction zone at the volcanic arc surface, and its influence on mantle wedge deformation, are not well known. In particular, during basaltic liquid ascent through the mantle wedge, decreasing pressure and temperature changes are likely to induce significant compositional variations, especially in terms of dissolved water content. Relationships between melt transport and mantle wedge deformation are also not clearly understood. We present a numerical model of magma generation and transport in subduction zones, that simulates chemical, thermal, and mechanical interactions between fluids and solid rocks along the magma ascent pathway. Magma migration is modelled by a porous flow across a constant permeability matrix, while the solid downward current associated with subduction in the mantle wedge, is included. The heat advected by the percolating liquid phase as well as latent heat effect associated with melting will be included. Water exchanges between the molten rock and the solid matrix are computed as a function of pressure, temperature, and solubilities laws in melt. We will first present benchmark results to validate the porous flow modelling as well as the ernery equation resolution for a two- phase flow. The aqueous and magmatic fluid repartition within the mantle wedge will then be presented. Magma productivity rates, varying along the magma ascent path way, will be discussed as a function of magma viscosity.

  10. Estimating effective wedge factor for enhanced dynamic wedge 2100CD a Varian Clinac; Calculo De factor cuna efectiva para cuna dinamica mejorada de un Clinac 2100CD de Varian

    Energy Technology Data Exchange (ETDEWEB)

    Pizarro Trigo, F.; Morillas Ruiz, J.; Nunuz Martinez, L.; Sanchez Jimenez, J.

    2011-07-01

    The purpose of this paper is to compare different methods of calculating the effective factor enhanced dynamic wedge (EDWF) with the values ??obtained in measurements of symmetric and asymmetric fields.

  11. A Numerical Study on the Asymmetric Water Entry of A Wedge Section

    Institute of Scientific and Technical Information of China (English)

    M. S. Seif; S. M. Mousaviraad; S. H. Saddathosseini

    2004-01-01

    The effect of the asymmetric water entry over a submerged part of a ship on the hydrodynamic impact is investigated numerically. A wedge body is considered and the problem is assumed to be two-dimensional. The results of symmetric and asymmetric impacts are compared. The effect is found significant in the numerical simulation. The maximum hydrodynamic pressure at a heel angle of 10 degrees becomes about 95% more than that of the symmetric entry. The result of the present work proves the importance of asymmetrical hydrodynamic impact loading for structural design of a ship. Besides, the numerical procedure is not limited to a wedge type cross section and it is possible to apply it for any real geometry of ships and high-speed craft.

  12. Generation of vector beams using a double-wedge depolarizer: Non-quantum entanglement

    Science.gov (United States)

    Samlan, C. T.; Viswanathan, Nirmal K.

    2016-07-01

    Propagation of horizontally polarized Gaussian beam through a double-wedge depolarizer generates vector beams with spatially varying state of polarization. Jones calculus is used to show that such beams are maximally nonseparable on the basis of even (Gaussian)-odd (Hermite-Gaussian) mode parity and horizontal-vertical polarization state. The maximum nonseparability in the two degrees of freedom of the vector beam at the double wedge depolarizer output is verified experimentally using a modified Sagnac interferometer and linear analyser projected interferograms to measure the concurrence 0.94±0.002 and violation of Clauser-Horne-Shimony-Holt form of Bell-like inequality 2.704±0.024. The investigation is carried out in the context of the use of vector beams for metrological applications.

  13. Plasmonic angular momentum on metal-dielectric nano-wedges in a sectorial indefinite metamaterial

    CERN Document Server

    Jin, Dafei

    2013-01-01

    We present an analytical study to the structure-modulated plasmonic angular momentum trapped on periodic metal-dielectric nano-wedges in the core region of a sectorial indefinite metamaterial. Employing a transfer-matrix calculation and a conformal-mapping technique, our theory is capable of dealing with realistic configurations of arbitrary sector numbers and rounded wedge tips. We demonstrate that in the deep-subwavelength regime strong electric field carrying high azimuthal variation can exist within only ten-nanometer length scale close to the structural center, and is naturally bounded by a characteristic radius of the order of hundred-nanometer away from the center. These extreme confining properties suggest that the structure under investigation may be superior to the conventional metal-dielectric waveguides or cavities in terms of nanoscale photonic manipulation.

  14. Experiments on melt-rock reaction in the shallow mantle wedge

    Science.gov (United States)

    Mitchell, Alexandra L.; Grove, Timothy L.

    2016-12-01

    This experimental study simulates the interaction of hotter, deeper hydrous mantle melts with shallower, cooler depleted mantle, a process that is expected to occur in the upper part of the mantle wedge. Hydrous reaction experiments ( 6 wt% H2O in the melt) were conducted on three different ratios of a 1.6 GPa mantle melt and an overlying 1.2 GPa harzburgite from 1060 to 1260 °C. Reaction coefficients were calculated for each experiment to determine the effect of temperature and starting bulk composition on final melt compositions and crystallizing assemblages. The experiments used to construct the melt-wall rock model closely approached equilibrium and experienced phase equilibria, melt compositions, and reaction coefficients provide a framework for understanding how melt-wall rock reaction occurs in the natural system during melt ascent in the mantle wedge.

  15. Effects of radiation on convection heat transfer of Cu-water nanofluid past a moving wedge

    Directory of Open Access Journals (Sweden)

    Salama Faiza A.

    2016-01-01

    Full Text Available Heat transfer characteristics of a two-dimensional steady hydrodynamic flow of water-based copper(Cu nanofluid over a moving wedge, taking into account the effects of thermal radiation, have been investigated numerically. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing fundamental equations are first transformed into a system of ordinary differential equations and solved numerically by using the fourth-order Runge-kutta method with shooting technique. A comparison with previously published work has been carried out and the results are found to be in good agreement. The existence of unique and dual solutions for self-similar equations of the flow and heat transfer are analyzed numerically. The results indicate that there is strong dependence of the thermal gradient at the surface of the wedge on both velocity ratio parameter and thermal radiation.

  16. Wedge excision of the nail fold in the treatment of ingrown toenail.

    Science.gov (United States)

    Persichetti, Paolo; Simone, Pierfranco; Li Vecchi, Giancarlo; Di Lella, Filippo; Cagli, Barbara; Marangi, Giovanni Francesco

    2004-06-01

    Many treatment modalities of ingrown toenail are reported in the literature, often associated with unacceptably high recurrence rate. The authors present their technique, which aims at reducing the convexity of the nail fold. After complete removal of the nail plate and accurate debridement of the granulomatous tissue, a wedge-shaped ellipsis of skin and subcutaneous tissue, lateral to the affected nail fold, is removed. Approximation of the margins of the resulting defect determines eversion of the nail fold. One hundred twenty ingrown toenails were treated with the wedge excision of the nail fold at the outpatient clinic of the department of plastic surgery, Campus Bio-Medico University, Rome, Italy, between January 1998 and January 2002. Six recurrences were observed. In addition to the high cure rate, short postoperative pain duration, and morbidity as well as low risk of postoperative infection, the remarkable esthetic results achievable with this method are indicated.

  17. Refinement of the wedge bar technique for compression tests at intermediate strain rates

    Directory of Open Access Journals (Sweden)

    Stander M.

    2012-08-01

    Full Text Available A refined development of the wedge-bar technique [1] for compression tests at intermediate strain rates is presented. The concept uses a wedge mechanism to compress small cylindrical specimens at strain rates in the order of 10s−1 to strains of up to 0.3. Co-linear elastic impact principles are used to accelerate the actuation mechanism from rest to test speed in under 300μs while maintaining near uniform strain rates for up to 30 ms, i.e. the transient phase of the test is less than 1% of the total test duration. In particular, a new load frame, load cell and sliding anvil designs are presented and shown to significantly reduce the noise generated during testing. Typical dynamic test results for a selection of metals and polymers are reported and compared with quasistatic and split Hopkinson pressure bar results.

  18. Heat Transfer Analysis of MHD Water Functionalized Carbon Nanotube Flow over a Static/Moving Wedge

    Directory of Open Access Journals (Sweden)

    Waqar A. Khan

    2015-01-01

    Full Text Available The MHD flow and heat transfer from water functionalized CNTs over a static/moving wedge are studied numerically. Thermal conductivity and viscosity of both single and multiple wall carbon nanotubes (CNTs within a base fluid (water of similar volume are investigated to determine the impact of these properties on thermofluid performance. The governing partial differential equations are converted into nonlinear, ordinary, and coupled differential equations and are solved using an implicit finite difference method with quasi-linearization techniques. The effects of volume fraction of CNTs and magnetic and wedge parameters are investigated and presented graphically. The numerical results are compared with the published data and are found to be in good agreement. It is shown that the magnetic field reduces boundary layer thickness and increases skin friction and Nusselt numbers. Due to higher density and thermal conductivity, SWCNTs offer higher skin friction and Nusselt numbers.

  19. Direct Preparation of Nano-Quasicrystals via a Water-Cooled Wedge-Shaped Copper Mould

    Directory of Open Access Journals (Sweden)

    Zhifeng Wang

    2012-01-01

    Full Text Available We have successfully synthesized multicomponent Mg-based nano-quasicrystals (nano-QCs through a simple route by using a water-cooled wedge-shaped copper mould. Nanoscale QCs are prepared directly on tip of wedge-shaped castings. The further study shows that nano-QCs in the Mg71Zn26Y2Cu1 alloy show well microhardness of greater than HV450. Electrochemical properties of three kinds of quasicrystal alloys are investigated in simulated seawater. The Mg71Zn26Y2Cu1 nano-QC alloy presents the best corrosion resistance in this study for the formation of well-distributed nano-QC phases (1~5 nm and polygonal Mg2(Cu,Y nanophases (40~50 nm.

  20. On the shape of a droplet in a wedge: new insight from electrowetting.

    Science.gov (United States)

    Baratian, D; Cavalli, A; van den Ende, D; Mugele, F

    2015-10-21

    The equilibrium morphology of liquid drops exposed to geometric constraints can be rather complex. Even for simple geometries, analytical solutions are scarce. Here, we investigate the equilibrium shape and position of liquid drops confined in the wedge between two solid surfaces at an angle α. Using electrowetting, we control the contact angle and thereby manipulate the shape and the equilibrium position of aqueous drops in ambient oil. In the absence of contact angle hysteresis and buoyancy, we find that the equilibrium shape is given by a truncated sphere, at a position that is determined by the drop volume and the contact angle. At this position, the net normal force between drop and the surfaces vanishes. The effect of buoyancy gives rise to substantial deviations from this equilibrium configuration which we discuss here as well. We eventually show how the geometric constraint and electrowetting can be used to position droplets inside a wedge in a controlled way, without mechanical actuation.

  1. Soil carbon sequestration is a climate stabilization wedge: comments on Sommer and Bossio (2014).

    Science.gov (United States)

    Lassaletta, Luis; Aguilera, Eduardo

    2015-04-15

    Sommer and Bossio (2014) model the potential soil organic carbon (SOC) sequestration in agricultural soils (croplands and grasslands) during the next 87 years, concluding that this process cannot be considered as a climate stabilization wedge. We argue, however, that the amounts of SOC potentially sequestered in both scenarios (pessimistic and optimistic) fulfil the requirements for being considered as wedge because in both cases at least 25 GtC would be sequestered during the next 50 years. We consider that it is precisely in the near future, and meanwhile other solutions are developed, when this stabilization effort is most urgent even if after some decades the sequestration rate is significantly reduced. Indirect effects of SOC sequestration on mitigation could reinforce the potential of this solution. We conclude that the sequestration of organic carbon in agricultural soils as a climate change mitigation tool still deserves important attention for scientists, managers and policy makers.

  2. 用楔子撬开问题%Using a Wedge to Pry Open a Problem

    Institute of Scientific and Technical Information of China (English)

    马提索夫

    2001-01-01

    When I elicited the Pumi word ts6 'wedge' in Kunming (March 1996), I was struck by its resemblance to Lahu jfl 'wedge'. Since the Qiangic languages are not particularly close to Loloish on the TB family tree,this apparent cognate for an item of non-core vocabulary was of interest. The first task in establishing a relationship between the Pumi and the Lahu forms was to reconstruct the PLB ancestor of Lahu jfi. Then possible cognates to the Pumi form in other Qiangic languages had to be examined.Given our present rudimentary knowledge of comparative Qiangic,could parallel examples establish a Proto-Qiangic reconstruction resembling our newly reconstructed PLB form?

  3. Behavior of the Siemens Virtual Wedge following an interruption to beam delivery.

    Science.gov (United States)

    Richmond, N D; Walker, C P

    2003-01-01

    Investigations were made into the beam profile shape and dose delivered by the Siemens Virtual Wedge trade mark under standard operational conditions compared with those following delivery interruption on two Siemens Primus linear accelerators (Type 7445 and 8067) running different versions of control software (7.2 and 7.0, respectively). The shape of the Virtual Wedge trade mark profiles was found to be unaffected by beam delivery interruption. An increase in the dose delivered to the central axis was found when delivery was interrupted and subsequently resumed using information recorded in a recall data file on one of the accelerators. This dose increase was attributed to a difference in delivered monitor units recorded in the recall data file compared to those displayed on the linear accelerator control console.

  4. Large negative Goos-H(a)nchen shift from a wedge-shaped thin film

    Institute of Scientific and Technical Information of China (English)

    Jianping Bai; Yaoju Zhang

    2009-01-01

    The analytical expression for the complex amplitude of light reflected from a wedge-shaped thin film is derived.For plane wave incidence,a simple ray tracing approach is used to calculate Goos-H(a)nchen(GH)shifts;and for non-plane wave incidence,for example,a Gaussian beam,the angular spectrum approach of plane wave is used in simulation.The two approaches predict that a wedge-shaped thin film can produce large negative longitudinal GH shifts.Although the reflectivity is small near the condition of resonance,the large negative GH shifts can be more easily detected in comparison with the shift from a plane-paxallel film in vacuum.

  5. Effect of ultrasonic power on wedge bonding strength and interface microstructure

    Institute of Scientific and Technical Information of China (English)

    WANG Fu-liang; LI Jun-hui; HAN Lei; ZHONG Jue

    2007-01-01

    During the aluminum wire wedge bonding, the ultrasonic power and bonding strength were obtained. Based on those data, the relationship between ultrasonic power and bonding strength was studied. The results show that: 1) ultrasonic power is affected by ultrasonic power ratio and other uncontrolled factors such as asymmetric substrate quality, unstable restriction on the interface between wedge tool and aluminum wire; 2) when ultrasonic power is less than 1.0 W, increasing ultrasonic power leads to increasing bonding strength and decreasing failure bonding; on the contrary, when ultrasonic power is greater than 1.6 W, increasing power leads to decreasing bonding strength and increasing failure bonding; 3) only when ultrasonic power is between 1.0 W and 1.6 W, can stable and high yield bonding be reached. Finally, the microstructure of bonding interface was observed, and a ring-shaped bond pattern is founded in the center and friction scrape besides the ring area.

  6. Analytic Study of Magnetohydrodynamic Flow and Boundary Layer Control Over a Wedge

    Institute of Scientific and Technical Information of China (English)

    M. Chandrasekar; S. Baskaran

    2008-01-01

    A genuine variational principle developed by Gyarmati, in the field of thermodynamics of irreversible processes unifying the theoretical requirements of technical, environmental and biological sciences is employed to study the effects of uniform suction and injection on MHD flow adjacent to an isothermal wedge with pressure gradient in the presence of a transverse magnetic field. The velocity distribution inside the boundary layer has been considered as a simple polynomial function and the variational principle is formulated. The Euler-Lagrange equation is reduced to a simple polynomial equation in terms of momentum boundary layer thickness. The velocity profiles, displacement thickness and the coefficient of skin friction are calculated for various values of wedge angle parameter m, magnetic parameter ε and suction/injection parameter H. The present results are compared with known available results and the comparison is found to be satisfactory. The present study establishes high accuracy of results obtained by this variational technique.

  7. On the Effect of Structural Response on the Hydrodynamic Loading of a Free-Falling Wedge

    Science.gov (United States)

    Ikeda, Christine; Taravella, Brandon; Judge, Carolyn

    2016-11-01

    High-speed planing craft are subjected to repeated slamming events in waves that can be very extreme depending on the wave topography, impact angle of the ship, forward speed of the ship, encounter angle, and height out of the water. The current work examines this fluid-structure interaction problem through the use of wedge drop experiments and a theoretical prediction. The experimental program consisted of two 20° deadrise angle wedges dropped from a range of heights, 0 . 15 code assumes a rigid structure, therefore, the results between the code and the first experiment are in good agreement. The second experiment shows pressure magnitudes that are lower than the predictions due to the energy required to deform the structure. This work is funded by the Office of Naval Research and the state of Louisiana Board of Regents Industrial Ties and Reseach Subprogram.

  8. A Single Photon Imaging System Based on Wedge and Strip Anodes

    Institute of Scientific and Technical Information of China (English)

    MIAO Zhen-Hua; ZHAO Bao-Sheng; ZHANG Xing-Hua; LIU Yong-An

    2008-01-01

    A new prototype of single photon imaging system based on wedge and strip anodes is developed. The prototype can directly measure the intensity and position information for an ultra-weak radiant source which takes on the character of single photons. The image of the ultra-weak radiant source can be reconstructed with a wedge and strip anodes detector and an electronic readout subsystem by photon counting and photon position sensitive detecting in a period of time. With proper evaluation, the prototype reveals a spatial resolution superior to 150μm, a 66-kHz maximal counting rate and a dark-count below 0.67count/cm2s.

  9. Transpressive suture and flower structure: the Tomar-Badajoz-Cordoba shear zone, SW Iberia

    Science.gov (United States)

    Marti Linares, D.; Palomeras, I.; Perez-Estaun, A.; Carbonell, R.; Simancas, F.; Ayarza, P.; Tejero, R.; Martín-Parra, L.; Matas, J.; Lodeiro, F.; Mansilla, L.

    2009-12-01

    The Tomar-Badajoz-Córdoba shear Zone (TBCSZ) is a major structural element located in SW-Iberia. This is considered a suture that separates the Central Iberian Zone (CIZ) in NE and Ossa Morena Zone (OMZ) in SW. It is at least 380km in length and 10 to 20km width. It is a left lateral transpressive flower structure. The strike-slip displacement decays from SE to NW. Its axial zone includes a high grade metamorphic rock unit known as the Central Unit (CU) containing eclogites, and also suture lithotypes as ophiolites. It has been interpreted as a Variscan suture or a reworked Cadomian suture in intraplate regime during the Variscan cycle. This important structure has been imaged by 2 deep seismic reflection transects, the IBERSEIS in 2003 and more recently by ALCUDIA. The good quality of the seismic data sets constrains the internal architecture of this transpressional zone imaging a crustal scale flower structure. The structure features a north dipping wedge limited by two bands of reflectors that reach the middle crust (5 s). Beneath that and slightly to the north a wedge of relatively high amplitude reflectivity dips to the south into the mantle for 10-15 km. This structure is most probably the seismic signature of a complex structure result of deformation associated to a strike slip fault.

  10. P and S wave attenuation tomography of the Japan subduction zone

    Science.gov (United States)

    Wang, Zewei; Zhao, Dapeng; Liu, Xin; Chen, Chuanxu; Li, Xibing

    2017-04-01

    We determine the first high-resolution P and S wave attenuation (Q) tomography beneath the entire Japan Islands using a large number of high-quality t∗ data collected from P and S wave velocity spectra of 4222 local shallow and intermediate-depth earthquakes. The suboceanic earthquakes used in this study are relocated precisely using sP depth phases. Significant landward dipping high-Q zones are revealed clearly, which reflect the subducting Pacific slab beneath Hokkaido and Tohoku, and the subducting Philippine Sea (PHS) slab beneath SW Japan. Prominent low-Q zones are visible in the crust and mantle wedge beneath the active arc volcanoes in Hokkaido, Tohoku, and Kyushu, which reflect source zones of arc magmatism caused by fluids from the slab dehydration and corner flow in the mantle wedge. Our results also show that nonvolcanic low-frequency earthquakes (LFEs) in SW Japan mainly occur in the transition zone between a narrow low-Q belt and its adjacent high-Q zones right above the flat segment of the PHS slab. This feature suggests that the nonvolcanic LFEs are caused by not only fluid-affected slab interface but also specific conditions such as high pore pressure which is influenced by the overriding plate.

  11. Evolution of Landau levels in graphene-based topological insulators in the presence of wedge disclinations

    CERN Document Server

    Oliveira, J R S; Furtado, C; Sergeenkov, S

    2016-01-01

    In this paper we consider modification of electronic properties of graphene-based topological insulator in the presence of wedge disclination and magnetic field by adopting the Kane-Mele model with intrinsic spin-orbit coupling. Using the properly defined Dirac-Weyl equation for this system, an exact solution for the Landau levels is obtained. The influence of the topological defect on the evolution of Landau levels is discussed.

  12. Margin Distance Does Not Influence Recurrence and Survival After Wedge Resection for Lung Cancer.

    Science.gov (United States)

    Maurizi, Giulio; D'Andrilli, Antonio; Ciccone, Anna Maria; Ibrahim, Mohsen; Andreetti, Claudio; Tierno, Simone; Poggi, Camilla; Menna, Cecilia; Venuta, Federico; Rendina, Erino Angelo

    2015-09-01

    The relationship between the free margin distance and the recurrence rate and overall survival after R0 wedge resection for non-small cell lung cancer (NSCLC) is still not clear. We retrospectively evaluated the long-term oncologic outcome of patients who had undergone wedge resection for NSCLC to assess the prognostic effect of margin distance in this setting. Between 2003 and 2013, 243 consecutive patients with a functional contraindication to major lung resection underwent wedge resection with systematic lymph node dissection for clinical stage I NSCLC. The study enrolled 182 patients with pathologic stage I and R0 resection and divided them into three subgroups according to margin distance of less than 1 cm (n = 30), 1 to 2 cm (n = 80), and more than 2 cm (n = 72). The histologic assessment was adenocarcinoma in 112 patients, squamous cell in 30, and other in 40. Postoperative morbidity was 18.7%, and postoperative mortality was 1.1%. The median follow-up was 31 months (range, 2 to 133 months). The locoregional (lung parenchyma, hilum, mediastinum) recurrence rate was 26.4% (n = 48). The distant recurrence rate was 11% (n = 20). Overall 5-year survival was 70.4%. Disease-free 5-year survival was 51.7%. There was no statistical difference in locoregional (p = 0.9) and distant (p = 0.3) recurrence rate and no difference in overall survival (p = 0.07) when the three groups were compared. Wedge resection is a viable option for the surgical treatment of stage I NSCLC when lobectomy is contraindicated. The distance between the tumor and the parenchymal suture margin does not influence recurrence or the survival rate when an R0 resection is achieved. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  13. A Concise UTD Formulation for the Scattering by a Wedge with Impedance Faces

    Institute of Scientific and Technical Information of China (English)

    YUAN Fei; ZHU Guo-qiang

    2004-01-01

    A concise formulation of the uniform geometrical theory of diffraction (UTD) solution for the scattering by a wedge with isotropic impedance faces at a plane wave normally incident case is deduced in this paper, which inherits the uniformity of the original result. It overcomes the complexity of the former, expresses clearly physical meanings, and is very prone to calculation with computer. The numerical results agree well with those given by published papers.

  14. Supersonic flow onto solid wedges, multidimensional shock waves and free boundary problems

    Science.gov (United States)

    Chen, Gui-Qiang

    2017-08-01

    When an upstream steady uniform supersonic flow impinges onto a symmetric straight-sided wedge, governed by the Euler equations, there are two possible steady oblique shock configurations if the wedge angle is less than the detachment angle -- the steady weak shock with supersonic or subsonic downstream flow (determined by the wedge angle that is less or larger than the sonic angle) and the steady strong shock with subsonic downstream flow, both of which satisfy the entropy condition. The fundamental issue -- whether one or both of the steady weak and strong shocks are physically admissible solutions -- has been vigorously debated over the past eight decades. In this paper, we survey some recent developments on the stability analysis of the steady shock solutions in both the steady and dynamic regimes. For the static stability, we first show how the stability problem can be formulated as an initial-boundary value type problem and then reformulate it into a free boundary problem when the perturbation of both the upstream steady supersonic flow and the wedge boundary are suitably regular and small, and we finally present some recent results on the static stability of the steady supersonic and transonic shocks. For the dynamic stability for potential flow, we first show how the stability problem can be formulated as an initial-boundary value problem and then use the self-similarity of the problem to reduce it into a boundary value problem and further reformulate it into a free boundary problem, and we finally survey some recent developments in solving this free boundary problem for the existence of the Prandtl-Meyer configurations that tend to the steady weak supersonic or transonic oblique shock solutions as time goes to infinity. Some further developments and mathematical challenges in this direction are also discussed.

  15. Hemi-wedge osteotomy in the management of large angular deformities around the knee joint.

    Science.gov (United States)

    El-Alfy, Barakat Sayed

    2016-08-01

    Angular deformity around the knee joint is a common orthopedic problem. Many options are available for the management of such problem with varying degrees of success and failure. The aim of the present study was to assess the results of hemi-wedge osteotomy in the management of big angular deformities about the knee joint. Twenty-eight limbs in 21 patients with large angular deformities around the knee joint were treated by the hemi-wedge osteotomy technique. The ages ranged from 12 to 43 years with an average of 19.8 years. The deformity ranged from 20° to 40° with a mean of 30.39° ± 5.99°. The deformities were genu varum in 12 cases and genu valgum in 9 cases. Seven cases had bilateral deformities. Small wedge was removed from the convex side of the bone and put in the gap created in the other side after correction of the deformity. At the final follow-up, the deformity was corrected in all cases except two. Full range of knee movement was regained in all cases. The complications included superficial wound infection in two cases, overcorrection in one case, pain along the lateral aspect of the knee in one case and recurrence of the deformity in one case. No cases were complicated by nerve injury or vascular injury. Hemi-wedge osteotomy is a good method for treatment of deformities around the knee joint. It can correct large angular deformities without major complications.

  16. Solution for a system of fractional heat equations of nanofluid along a wedge

    Directory of Open Access Journals (Sweden)

    Ibrahim Rabha W.

    2015-01-01

    Full Text Available In this article, authors set a new system of fractional heat equations of nanofluid along a wedge and establish the existence and uniqueness of a solution based on the Riemann-Liouville differential operators. Sufficient conditions on the parameters of the system are imposed. A numerical solution of the system is discussed, and applications are illustrated. The technique is based on the ability of Podlubny’s matrix in Matlab to formulate the operation of fractional calculus.

  17. 2D Traveling Wave Array Employing a Trapezoidal Dielectric Wedge for Beam Steering

    Science.gov (United States)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranada, Felix A.

    2014-01-01

    This presentation addresses the progress made so far in the development of an antenna array with reconfigurable transmission line feeds connecting each element in series. In particular, 2D traveling wave array employing trapezoidal Dielectric Wedge for Beam Steering will be discussed. The presentation includes current status of the effort and suggested future work. The work is being done as part of the NASA Office of the Chief Technologist's Space Technology Research Fellowship (NSTRF).

  18. Three-dimensional velocity structure of the outer fore arc of the Colombia-Ecuador subduction zone and implications for the 1958 megathrust earthquake rupture zone

    Science.gov (United States)

    García Cano, Lina Constanza; Galve, Audrey; Charvis, Philippe; Marcaillou, Boris

    2014-02-01

    In 2005, an onshore, offshore 3-D refraction and wide-angle reflection seismic experiment was conducted along the convergent margin at the border between Colombia and Ecuador, over the rupture zone of the 1958, Mw 7.6 subduction earthquake. A well-defined Vp velocity model of the plate boundary and upper and lower plates was constructed, down to 25 km depth, using first arrival traveltimes inversion. The model reveals a several kilometers thick, low-velocity zone in the upper plate, located immediately above the interplate contact. This low-velocity zone might be related to alteration and fracturing of the mafic and ultramafic rocks, which composed the upper plate in this area by fluids released by the lower plate with possible contributions from sediment underplating. Near the toe of the margin, the model shows a low-velocity gradient in the outer wedge, which is interpreted as highly faulted and fractured rocks. This low-velocity/low-gradient region appears to limit the oceanward extension of the rupture zones of the 1958 and 1979 earthquakes, possibly because coseismic deformation and uplift of the outer margin wedge dissipates most of the seismic energy.

  19. Comparative Study between a Curved and a Wedge PEEK Cage for Single-level Anterior Cervical Discectomy and Interbody Fusion

    National Research Council Canada - National Science Library

    Kim, Hwan Soo; Song, Joon Suk; Heo, Weon; Cha, Jae Hoon; Rhee, Dong Youl

    2012-01-01

    This study evaluated the efficiency of a curved polyetheretherketone (PEEK) cage in comparison with a wedge PEEK cage according to radiologic and clinical outcomes in patients with cervical degenerative disease...

  20. Fluid-present melting of sulfide-bearing ocean-crust: Experimental constraints on the transport of sulfur from subducting slab to mantle wedge

    Science.gov (United States)

    Jégo, Sébastien; Dasgupta, Rajdeep

    2013-06-01

    2 and 3 GPa was observed. This is interpreted as a consequence of comparable S speciation in the hydrous fluid phase in fO2 conditions ranging from NNO - 0.5 to CCO - 1.0 at 2 and 3 GPa and 850 to 1050 °C. Under these reducing conditions, the hydrous fluid phase is composed mainly of H2S and H2O, and to a lesser extent of S2 and H2, and S in melt is dissolved almost totally as S2- (i.e., S6+/Stotal ˜ 0). Our study suggests that slab-derived aqueous fluids with reduced sulfur species could be sufficient vectors for the transport of sulfur from the slab to the mantle wedge and only ˜0.3 to 1.5 wt.% of slab fluids are required for the mantle wedge enrichment in sulfur over background mantle concentrations. Also, depending on the initial amount of sulfur in the slab, recycling of sulfide to the deep mantle may be favored in cold to intermediate subduction zones, whereas warm subduction zones will cause fluid-mediated slab-mantle wedge transfer of sulfur.

  1. Cubitus varus in adults correction with lateral closing wedge osteotomy and fixation with posterior plating

    Directory of Open Access Journals (Sweden)

    S Pandey

    2012-09-01

    Full Text Available To share the result of lateral closing wedge osteotomy and fixation with posterior reconstruction plate in correction of cubitus varus in adults. It is a retrospective case analysis of 8 cases of cubitus varus in adult treated with lateral closing wedge osteotomy through posterior triceps retracting approach. Internal fixation was done with two posterior reconstruction plates. All cases were from 15 to 29 years of age (mean 22.3 with 3 female and 5 male. All had cubitus varus ranging from 15- 28 deg (mean 20.16 deg due to childhood malunited supracondylar fracture of humerus. Indication for operation was cosmetic reason only. Follow up duration was 4-22 months (mean 12.5 months. All the osteotomy united clinically in mean duration of 9 weeks ( range 8-12 weeks with mean carrying angle 8.33 degree in postoperative phase. There was no loss of motion, no loss of fixation, no surgical site infection, nonunion or neurovascular deficit. Lateral closing wedge corrective osteotomy and fixation with posterior reconstruction plate is easy technique with satisfactory result in correction of cubitus varus in adults. Journal of College of Medical Sciences-Nepal,2012,Vol-8,No-2, 49-53 DOI: http://dx.doi.org/10.3126/jcmsn.v8i2.6839

  2. Duodenal Wedge Resection for Large Gastrointestinal Stromal Tumour Presenting with Life-Threatening Haemorrhage

    Directory of Open Access Journals (Sweden)

    Alexander Shaw

    2013-01-01

    Full Text Available Background. Duodenal gastrointestinal stromal tumours (GISTs are an uncommon malignancy of the gastrointestinal (GI tract. We present a case of life-threatening haemorrhage caused by a large ulcerating duodenal GIST arising from the third part of the duodenum managed by a limited duodenal wedge resection. Case Presentation. A 61-year-old patient presented with acute life-threatening gastrointestinal bleeding. After oesophagogastroduodenoscopy failed to demonstrate the source of bleeding, a 5 cm ulcerating exophytic mass originating from the third part of the duodenum was identified at laparotomy. A successful limited wedge resection of the tumour mass was performed. Histopathology subsequently confirmed a duodenal GIST. The patient remained well at 12-month followup with no evidence of local recurrence or metastatic spread. Conclusion. Duodenal GISTs can present with life-threatening upper GI haemorrhage. In the context of acute haemorrhage, even relatively large duodenal GISTs can be treated by limited wedge resection. This is a preferable alternative to duodenopancreatectomy with lower morbidity and mortality but comparable oncological outcome.

  3. Analysis of stress-strain state on top of a rectangular wedge

    Directory of Open Access Journals (Sweden)

    Frishter Lyudmila Yur'evna

    2014-05-01

    Full Text Available Modeling singular solutions of the elasticity theory problems, which are determined by geometric factor - bird's mouth of the edge, make it necessary to analyze the solutions with some peculiarity, which are obtained experimentally with the help of photoelasticity method. In this article the peculiar stress-strain state is analyzed on the example of the known experimental solutions for a wedge under a concentrated force obtained by M. Frocht. Solution analysis for a wedge with a power-type peculiarity obtained experimentally by photoelasticity method, helps to detach a singular solution field, where fringe contour is not visible. Due to idealization of the boundary shape and loading technique, infinitely large stresses arise, which are obtained as a singular solution of the boundary problem in a planar domain. Comparison of theoretical and experimental solutions obtained for a wedge shows areas of overlap and areas of significant and insignificant differences as a result of the inability to experimentally apply the force to a single point.

  4. Dose conformation to the spine during palliative treatments using dynamic wedges

    Energy Technology Data Exchange (ETDEWEB)

    Ormsby, Matthew A., E-mail: Matthew.Ormsby@usoncology.com [West Texas Cancer Center at Medical Center Hospital, Odessa, TX (United States); Herndon, R. Craig; Kaczor, Joseph G. [West Texas Cancer Center at Medical Center Hospital, Odessa, TX (United States)

    2013-07-01

    Radiation therapy is commonly used to alleviate pain associated with metastatic disease of the spine. Often, isodose lines are manipulated using dynamic or physical wedges to encompass the section of spine needing treatment while minimizing dose to normal tissue. We will compare 2 methods used to treat the entire thoracic spine. The first method treats the thoracic spine with a single, nonwedged posterior-anterior (PA) field. Dose is prescribed to include the entire spine. Isodose lines tightly conform to the top and bottom vertebrae, but vertebrae between these 2 received more than enough coverage. The second method uses a combination of wedges to create an isodose line that mimics the curvature of the thoracic spine. This “C”-shaped curvature is created by overlapping 2 fields with opposing dynamic wedges. Machine constraints limit the treatment length and therefore 2 isocenters are used. Each of the 2 PA fields contributes a portion of the total daily dose. This technique creates a “C”-shaped isodose line that tightly conforms to the thoracic spine, minimizing normal tissue dose. Spinal cord maximum dose is reduced, as well as mean dose to the liver, esophagus, and heart.

  5. Analysis of Mechanical Energy Transport on Free-Falling Wedge during Water-Entry Phase

    Directory of Open Access Journals (Sweden)

    Wen-Hua Wang

    2012-01-01

    Full Text Available For better discussing and understanding the physical phenomena and body-fluid interaction of water-entry problem, here mechanical-energy transport (wedge, fluid, and each other of water-entry model for free falling wedge is studied by numerical method based on free surface capturing method and Cartesian cut cell mesh. In this method, incompressible Euler equations for a variable density fluid are numerically calculated by the finite volume method. Then artificial compressibility method, dual-time stepping technique, and Roe's approximate Riemann solver are applied in the numerical scheme. Furthermore, the projection method of momentum equations and exact Riemann solution are used to calculate the fluid pressure on solid boundary. On this basis, during water-entry phase of the free-falling wedge, macroscopic energy conversion of overall body-fluid system and microscopic energy transformation in fluid field are analyzed and discussed. Finally, based on test cases, many useful conclusions about mechanical energy transport for water entry problem are made and presented.

  6. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling

    Science.gov (United States)

    Parry, Andrew O.; Rascón, Carlos

    2011-01-01

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  7. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling

    Energy Technology Data Exchange (ETDEWEB)

    Parry, Andrew O [Department of Mathematics, Imperial College London, London SW7 2BZ (United Kingdom); Rascon, Carlos [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, 28911 Leganes, Madrid (Spain)

    2011-01-12

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  8. Spatial variability of E. coli in an urban salt-wedge estuary.

    Science.gov (United States)

    Jovanovic, Dusan; Coleman, Rhys; Deletic, Ana; McCarthy, David

    2017-01-15

    This study investigated the spatial variability of a common faecal indicator organism, Escherichia coli, in an urban salt-wedge estuary in Melbourne, Australia. Data were collected through comprehensive depth profiling in the water column at four sites and included measurements of temperature, salinity, pH, dissolved oxygen, turbidity, and E. coli concentrations. Vertical variability of E. coli was closely related to the salt-wedge dynamics; in the presence of a salt-wedge, there was a significant decrease in E. coli concentrations with depth. Transverse variability was low and was most likely dwarfed by the analytical uncertainties of E. coli measurements. Longitudinal variability was also low, potentially reflecting minimal die-off, settling, and additional inputs entering along the estuary. These results were supported by a simple mixing model that predicted E. coli concentrations based on salinity measurements. Additionally, an assessment of a sentinel monitoring station suggested routine monitoring locations may produce conservative estimates of E. coli concentrations in stratified estuaries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Partial wedge resection of nail, nail bed and nail matrix in ingrown toenail treatment

    Directory of Open Access Journals (Sweden)

    Mustafa Dönmez

    2010-05-01

    Full Text Available Objectives: Ingrown toenail is a frequent problem which can be seen in all ages. There are many treatment methods both surgical and nonsurgical. In this study we evaluated the results of wedge resection of ingrown toe nail.Patients and Methods: A total of 80 toenails of 74 patients (55 female, 19 male who complaint with discharge and deformity of their toenail underwent partial wedge resection of the nail and nail matrix. According to the Heifetz’s staging system, 34 toenails were grade II, 46 toenails were grade III. There was active drainage due to an infectious process in all effected toe nails. All patients were operated after 10 day of oral antibiotic treatment. We evaluated the recurrence, postoperative infection, patient satisfaction and time to return to work.Results: The mean follow up period was 8 months (4-12 months. There was no recurrence in any patient. Two patients came with wound drainage in postoperative 14th day. Intravenous antibiotic treatment, debridement and wound dressing with rifampicine every other day were accomplished. All patients expressed their satisfaction with surgery.Conclusion: In treatment of ingrown toenail; wedge resection of nail, nail matrix and nail bed is a very effective treatment. Recurrence rate following this technique is negligible if it is done properly and it has high patient satisfaction.

  10. Computational analysis of asymmetric water entry of wedge and ship section at constant velocity

    Science.gov (United States)

    Rahaman, Md. Mashiur; Ullah, Al Habib; Afroz, Laboni; Shabnam, Sharmin; Sarkar, M. A. Rashid

    2016-07-01

    Water impact problems receive much attention due to their short duration and large unsteady component of hydrodynamic loads. The effect of water entry has several important applications in various aspects of the naval field. Significant attention has been given to various water entry phenomena such as ship slamming, planning hulls, high-speed hydrodynamics of seaplanes, surface-piercing propellers and the interaction of high-speed liquid drops with structural elements. Asymmetric water entry may be caused by various natural phenomena such as weather conditions or strong winds. Since the determination of hydrodynamic impact load plays a vital role in designing safe and effcient vessels, an accurate and reliable prediction method is necessary to investigate asymmetric water entry problems. In this paper, water entry of a two-dimensional wedge and ship section at constant velocity in asymmetric condition will be analysed numerically and the effects of asymmetric impact on the velocity and pressure distribution will be discussed. The finite volume method is employed to solve the dynamic motion of the wedge in two-phase flow. During the water entry, the air and water interface is described implicitly by the volume of fluid (VOF) scheme. The numerical code and method was first validated for symmetric condition by one of the present author is applied for asymmetric wedge and ship section. The free surface, velocity and pressure distribution for asymmetric water entry are investigated and visualized with contour plots at different time steps.

  11. Extension of a double-wedged orogen potentially leads to the current South China Sea

    Science.gov (United States)

    Wu, G.; Lavier, L. L.

    2015-12-01

    The South China Sea (SCS) is surrounded by South China on the NW, Palawan and Reed Bank on the SE, as well as several microplates, resembling a jigsaw puzzle. In an attempt to better understand its evolution, we designed simplified thermomechanical models to simulate extension of a double-wedge-shaped orogen with highlands on both sides and lowland in the center to mimic the geological condition of the proto-SCS. We imposed constant extension rates on both sides and Gaussian-shaped thermal impulse in the center. We also varied the strength of lower crust but did not explicitly incorporate mid-ocean ridges and searfloor spreading mechanisms. We currently used symmetric double-wedge, but further tests are planed for asymmetric double-wedges. Our preliminary results show that the models produced many structures that resemble those of SCS, such as 1) a series of domino or conjugate faults sitting above a subsurface detachment (or décollement), 2) exhumed domes of middle-lower crust, 3) extreme thinning of both upper crust and lower crust, and 4) propagation of extension towards NW and SE margins. Our models suggest that superimposition of these modeled characteristics produced during several phases of extension of the SCS that may be due to thermal impulsion, magmatic events, and subduction related relaxation potentially produces high resemblance of the SCS.

  12. Analysis and design of wedge projection display system based on ray retracing method.

    Science.gov (United States)

    Lee, Chang-Kun; Lee, Taewon; Sung, Hyunsik; Min, Sung-Wook

    2013-06-10

    A design method for the wedge projection display system based on the ray retracing method is proposed. To analyze the principle of image formation on the inclined surface of the wedge-shaped waveguide, the bundle of rays is retraced from an imaging point on the inclined surface to the aperture of the waveguide. In consequence of ray retracing, we obtain the incident conditions of the ray, such as the position and the angle at the aperture, which provide clues for image formation. To illuminate the image formation, the concept of the equivalent imaging point is proposed, which is the intersection where the incident rays are extended over the space regardless of the refraction and reflection in the waveguide. Since the initial value of the rays arriving at the equivalent imaging point corresponds to that of the rays converging into the imaging point on the inclined surface, the image formation can be visualized by calculating the equivalent imaging point over the entire inclined surface. Then, we can find image characteristics, such as their size and position, and their degree of blur--by analyzing the distribution of the equivalent imaging point--and design the optimized wedge projection system by attaching the prism structure at the aperture. The simulation results show the feasibility of the ray retracing analysis and characterize the numerical relation between the waveguide parameters and the aperture structure for on-axis configuration. The experimental results verify the designed system based on the proposed method.

  13. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling.

    Science.gov (United States)

    Parry, Andrew O; Rascón, Carlos

    2011-01-12

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  14. Flow Visualization around a Double Wedge Airfoil Model with Focusing Schlieren System

    Institute of Scientific and Technical Information of China (English)

    Masashi KASHITANI; Yutaka YAMAGUCHI

    2006-01-01

    In the present study, aerodynamic characteristics of the double wedge airfoil model were investigated in a transonic flow by using the shock tube as an intermittent wind tunnel. The driver and driven gases of the shock tube are dry air. The airfoil model of double wedge has the span of 58 mm, chord length c = 75 mm and its maximum thickness is 7.5 mm. The apex of the double wedge airfoil model is located on the 35% chord length from the leading edge. The range of hot gas Mach numbers are from 0.80 to 0.88, and the Reynolds numbers based on chord length are 3.11×105~3.49×105, respectively. The flow visualizations were performed by the sharp focusing schlieren method which can visualize the three dimensional flow fields. The results show that the present system can visualize the transonic flowfield clearer than the previous system, and the shock wave profiles of the center of span in the test section are visualized

  15. Plastic ingestion by Newell's (Puffinus newelli) and wedge-tailed shearwaters (Ardenna pacifica) in Hawaii.

    Science.gov (United States)

    Kain, Elizabeth C; Lavers, Jennifer L; Berg, Carl J; Raine, André F; Bond, Alexander L

    2016-12-01

    The ingestion of plastic by seabirds has been used as an indicator of pollution in the marine environment. On Kaua'i, HI, USA, 50.0 % of Newell's (Puffinus newelli) and 76.9 % of wedge-tailed shearwater (Ardenna pacifica) fledglings necropsied during 2007-2014 contained plastic items in their digestive tract, while 42.1 % of adult wedge-tailed shearwaters had ingested plastic. For both species, the frequency of plastic ingestion has increased since the 1980s with some evidence that the mass and the number of items ingested per bird have also increased. The color of plastic ingested by the shearwaters was assessed relative to beach-washed plastics by using Jaccard's index (where J = 1 complete similarity). The color (J = 0.65-0.68) of items ingested by both species, and the type ingested by wedge-tailed shearwaters (J = 0.85-0.87), overlapped with plastic available in the local environment indicating moderate selection for plastic color and type. This study has shown that the Hawaiian populations of shearwaters, like many seabird species, provide useful but worrying insights into plastic pollution and the health of our oceans.

  16. Midterm results following medial closed wedge distal femoral osteotomy stabilized with a locking internal fixation device.

    Science.gov (United States)

    Forkel, Philipp; Achtnich, Andrea; Metzlaff, Sebastian; Zantop, Thore; Petersen, Wolf

    2015-07-01

    Aim of this study was to evaluate the subjective and radiological outcome and to evaluate the complications of a medial closing wedge osteotomy at the femur for lateral osteoarthritis with genu valgum. Twenty-three patients with grade III to IV cartilage damage and valgus knee alignment were treated with medial closing wedge osteotomy at the distal femur. The osteotomy was stabilized with an internal plate fixator. Age varied between 25 and 55 years (mean 47 years). One patient was lost to final follow-up. After 3.5 years, all Knee Osteoarthritis Outcome Score (KOOS) subitems increased significantly. There was no significant difference in the subgroup analysis of KOOS subitems for patients with and without microfracture or age (>50 vs. <50 years). There were no perioperative complications. One patient had an overcorrection. All, but one osteotomy, showed stable bone healing. There was a loss of correction due to delayed bone healing in one case. Possible explanations for this complication were injury of the lateral cortex or smoking. This case required revision with bone graft and an additional lateral plate. In no case, a conversion to an endoprosthesis was necessary. The femoral medial closing wedge osteotomy is a surgical method for improving symptoms of lateral osteoarthritis in the valgus knee. IV.

  17. CFD Simulations of the IHF Arc-Jet Flow: Compression-Pad/Separation Bolt Wedge Tests

    Science.gov (United States)

    Gokcen, Tahir; Skokova, Kristina A.

    2017-01-01

    This paper reports computational analyses in support of two wedge tests in a high enthalpy arc-jet facility at NASA Ames Research Center. These tests were conducted using two different wedge models, each placed in a free jet downstream of a corresponding different conical nozzle in the Ames 60-MW Interaction Heating Facility. Panel test articles included a metallic separation bolt imbedded in the compression-pad and heat shield materials, resulting in a circular protuberance over a flat plate. As part of the test calibration runs, surface pressure and heat flux measurements on water-cooled calibration plates integrated with the wedge models were also obtained. Surface heating distributions on the test articles as well as arc-jet test environment parameters for each test configuration are obtained through computational fluid dynamics simulations, consistent with the facility and calibration measurements. The present analysis comprises simulations of the non-equilibrium flow field in the facility nozzle, test box, and flow field over test articles, and comparisons with the measured calibration data.

  18. Integrated waste management as a climate change stabilisation wedge for the Maltese islands.

    Science.gov (United States)

    Falzon, Clyde; Fabri, Simon G; Frysinger, Steven

    2013-01-01

    The continuous increase in anthropogenic greenhouse gas emissions occurring since the Industrial Revolution is offering significant ecological challenges to Earth. These emissions are leading to climate changes which bring about extensive damage to communities, ecosystems and resources. The analysis in this article is focussed on the waste sector within the Maltese islands, which is the largest greenhouse gas emitter in the archipelago following the energy and transportation sectors. This work shows how integrated waste management, based on a life cycle assessment methodology, acts as an effective stabilisation wedge strategy for climate change. Ten different scenarios applicable to the Maltese municipal solid waste management sector are analysed. It is shown that the scenario that is most coherent with the stabilisation wedges strategy for the Maltese islands consists of 50% landfilling, 30% mechanical biological treatment and 20% recyclable waste export for recycling. It is calculated that 16.6 Mt less CO2-e gases would be emitted over 50 years by means of this integrated waste management stabilisation wedge when compared to the business-as-usual scenario. These scientific results provide evidence in support of policy development in Malta that is implemented through legislation, economic instruments and other applicable tools.

  19. Groundwater response to tidal fluctuations in wedge-shaped confined aquifers

    Science.gov (United States)

    Cuello, Julián E.; Guarracino, Luis; Monachesi, Leonardo B.

    2017-08-01

    Most of the analytical solutions to describe tide-induced head fluctuations assume that the coastal aquifer has a constant thickness. These solutions have been applied in many practical problems ignoring possible changes in aquifer thickness, which may lead to wrong estimates of the hydraulic parameters. In this study, a new analytical solution to describe tide-induced head fluctuations in a wedge-shaped coastal aquifer is presented. The proposed model assumes that the aquifer thickness decreases with the distance from the coastline. A closed-form analytical solution is obtained by solving a boundary-value problem with both a separation of variables method and a change of variables method. The analytical solution indicates that wedging significantly enhances the amplitude of the induced heads in the aquifer. However, the effect on time lag is almost negligible, particularly near the coast. The slope factor, which quantifies the degree of heterogeneity of the aquifer, is obtained and analyzed for a number of hypothetical scenarios. The slope factor provides a simple criterion to detect a possible wedging of the coastal aquifer.

  20. Automatic lumbar vertebra segmentation from clinical CT for wedge compression fracture diagnosis

    Science.gov (United States)

    Ghosh, Subarna; Alomari, Raja'S.; Chaudhary, Vipin; Dhillon, Gurmeet

    2011-03-01

    Lumbar vertebral fractures vary greatly in types and causes and usually result from severe trauma or pathological conditions such as osteoporosis. Lumbar wedge compression fractures are amongst the most common ones where the vertebra is severely compressed forming a wedge shape and causing pain and pressure on the nerve roots and the spine. Since vertebral segmentation is the first step in any automated diagnosis task, we present a fully automated method for robustly localizing and segmenting the vertebrae for preparation of vertebral fracture diagnosis. Our segmentation method consists of five main steps towards the CAD(Computer-Aided Diagnosis) system: 1) Localization of the intervertebral discs. 2) Localization of the vertebral skeleton. 3) Segmentation of the individual vertebra. 4) Detection of the vertebrae center line and 5) Detection of the vertebrae major boundary points. Our segmentation results are promising with an average error of 1.5mm (modified Hausdorff distance metric) on 50 clinical CT cases i.e. a total of 250 lumbar vertebrae. We also present promising preliminary results for automatic wedge compression fracture diagnosis on 15 cases, 7 of which have one or more vertebral compression fracture, and obtain an accuracy of 97.33%.

  1. Ground fracturing at the southern end of Summit Ridge caused by October 17, 1989 Loma Prieta, California, earthquake sequence (maps of Summit Ridge Shear Zones, en echelon tension cracks, complex and compound fractures, and small faults that formed coactively with the earthquake sequence)

    Energy Technology Data Exchange (ETDEWEB)

    Martosudarmo, S.Y. [BPP Technologi, Jakarta (Indonesia); Johnson, A.M. [Purdue Univ., West Lafayette, IN (United States). Harry Fielding Reid Earthquake Research Lab.; Fleming, R.W. [Geological Survey, Denver, CO (United States)

    1997-12-31

    The Loma Prieta earthquake of 17 October 1989 was the first of three large earthquakes that occurred in California in less than 5 years. The main shock of the Loma Prieta earthquake was deep-seated, the rupture zones of the main shock did not reach the surface, and the earthquake produced enigmatic surface ruptures along the frontal faults of the Coast Range and in the epicentral area that were explained in several quite different ways. The Landers earthquake of 28 June 1992 was near surface and produced more than 80 km of spectacular surface rupture of many different kinematic expressions. Detailed study of fractures at Landers has provided a basis for re-evaluating earlier work on fractures produced by the Loma Prieta earthquake. This paper is a description of some of the fractures produced by the Loma Prieta earthquake and a discussion of their causes. Detailed mapping (scale of 1:250) in an area on either side of Summit Road and between Morrell Cutoff Road in the northwest and the intersection of Summit Road and San Jose-Soquel Road in the southeast has provided documentation of fracture orientations and differential displacements required to decipher the ground deformation in that area during the Loma Prieta earthquake.

  2. FORMATION AND ENVIRONMENTAL EVOLUTION OF SAND WEDGES ON THE TIANSHUIHAI NORTH LAKESHORE IN THE WESTERN KUNLUN MOUNTAINS%西昆仑山甜水海北湖砂楔的形成与环境演变

    Institute of Scientific and Technical Information of China (English)

    常晓丽; 金会军; 何瑞霞

    2011-01-01

    Qinghai-Tibet Plateau is one of the most well developed periglacial areas within the low-middle latitude regions in the world. Tianshuihai, located in the Western Kunlun Mountains regions in the north-west of the Plateau , spreads widely with sand-wedges and other periglacial features. The sand-wedges, which were developed in cold climate conditions,are of important signif'icance for paleo-climate or paleo-environment reconstruction. At the 570km of Xin-Zang Highway ( i. e. G219 ) on the Tianshuihai North Lakeshore , a typical sand-wedge was found with the exact location 35°32. 968'N ,79°31. 821'E and the elevation about 4850m. It is irregular with 37cm in width at the top of sand-wedge but 50cm at the depth of 30cm from ground surface and 98cm in depth , with periglacial involution on the left side of sand-wedge and large compressed deformation and tilt on the right side of sand-wedge. There is a right-ward convex on the left at the depth of 60cm .and then the width of sand-wedge tapers off with the value of 6~8cm at the bottom of sand-wedge. As to lithology, surrounding rock is principally composed of gray silty soil interbedded , sandy loam and loam. The grain-size distribution,14C dating of organism and mineral composition were analyzed in the sand-wedge and the surrounding rock. The key findings are as follows.(1) The sand-wedge is mainly comprised of light minerals with debris accounting for 75% in weight, which indicates the provenance of infill materials of the wedge is nearby.(2) The sand-wedge could be distinctively divided into three sub-parts with respect to texture , grain-size and figure of the infill. of the results of 14C dating indicates that these three parts were formed in 11.5kaB. P.,11. 9kaB. P. and 13. 9kaB. P. , respectively , from the center to the periphery.( 3 ) Compared with the climate changing pattern derived from the ostracods research in the Sumxi Co Lake and Bangong Co Lake in the vicinity,these three sub-parts were all formed

  3. Abundance pattern of wedge clam Donax cuneatus (L.) in different spatial scale in the vicinity of a coastal nuclear power plant.

    Science.gov (United States)

    Hussain, K Jahir; Mohanty, A K; Satpathy, K K; Prasad, M V R

    2010-04-01

    Impact of thermal discharge from a coastal power station (Madras Atomic Power Station, southeast coast of India) on the spatial variability of Donax cuneatus abundance was assessed to determine the impact boundary. Totally, 20 sites were selected both on south and north side in increasing spatial scale from mixing zone, 12 locations were selected toward south side at a distance from 0 (near mixing point) to 2,000 m and eight location were selected toward north from the effluent mixing zone. Mean water temperature along the coast ranged from 29.1 +/-0.15 degrees C to 31.2 +/- 0.15 degrees C. Total organic carbon content in the sediment ranged from 0.27% to 0.70%. D. cuneatus population on the swash zone was ranged between 1.3 +/- 1.5 and 88.3 +/- 9.6 m(-2). Meager population of wedge clam was observed up to 100 m (S100) south from mixing point and abundance gradually increased in different spatial scale. Comparatively high abundance was observed from S400 and reached maximum at S1000 (64.0 +/- 3.6 m(-2)). Similar pattern was observed on north side too but less abundance was observed only up to 80 m (N80). Maximum abundance was observed at control location C3-N500 (88.3 +/- 9.6 m(-2)). Forty meters on either side of discharge point was highly impacted, 80 to 100 m toward plume flow (south) was moderately impacted, and 80 m north of mixing point also witnessed moderate impact. After 100 m (N100), north was not affected by effluents, whereas between 100 and 400 m, south was influenced slightly. Multivariate clustering pattern on the environmental variables of all sampling locations and population trend of D. cuneatus at those stations showed similarity. Present investigation unambiguously showed that the abundance pattern of D. cuneatus on the sandy beach of east coast of Kalpakkam is not governed by single major factor but due to the result of multiple interacting factors. The population size of the wedge clam with reference to the effect of power plant effluents and

  4. Open Wedge High Tibial Osteotomy and Combined Arthroscopic Surgery in Severe Medial Osteoarthritis and Varus Malalignment: Minimum 5-Year Results

    OpenAIRE

    Yoo, Moon-Jib; Shin, Yong-Eun

    2016-01-01

    Purpose To evaluate the radiologic and functional outcomes of medial open wedge high tibial osteotomy (HTO) combined with arthroscopic procedure in patients with medial osteoarthritis. Materials and Methods From June 1996 to March 2010, 26 patients (32 knees) who underwent medial open wedge osteotomy and arthroscopic operation for medial osteoarthritis were retrospectively reviewed. Measurements included hip-knee-ankle (HKA) angle, femorotibial angle, medial proximal tibial angle, posterior t...

  5. Modeling the role of back-arc spreading in controlling 3-D circulation and temperature patterns in subduction zones

    Science.gov (United States)

    Kincaid, C.

    2005-12-01

    Subduction of oceanic lithosphere provides a dominant driving force for mantle dynamics and plate tectonics, and strongly modulates the thermal evolution of the mantle. Magma generation in arc environments is related to slab temperatures, slab dehydration/wedge hydration processes and circulation patterns in the mantle wedge. A series of laboratory experiments is used to model three-dimensional aspects of flow in subduction zones, and the consequent temperature variations in the slab and overlying mantle wedge. The experiments utilize a tank of glucose syrup to simulate the mantle and a Phenolic plate to represent subducting oceanic lithosphere. Different modes of plate sinking are produced using hydraulic pistons. The effects of longitudinal, rollback and slab-steepening components of slab motions are considered, along with different thicknesses of the over-riding lithosphere. Models look specifically at how distinct modes of back-arc spreading alter subduction zone temperatures and flow in the mantle wedge. Results show remarkably different temperature and circulation patterns when spreading is produced by rollback of the trench-slab-arc relative to a stationary overriding back-arc plate versus spreading due to motion of the overriding plate away from a fixed trench location. For rollback-induced spreading, flow trajectories in the wedge are shallow (e.g., limited upwelling), both the sub-arc and back-arc regions are supplied by material flowing around the receding slab. Flow lines in the sub-arc wedge are strongly trench-parallel. In these cases, strong lateral variations in slab surface temperature (SST) are recorded (hot at plate center, cool at plate edge). When the trench is fixed in space and spreading is produced by motion of the overriding plate, strong vertical flow velocities are recorded in the wedge, both the shallow sub-arc and back-arc regions are supplied by flow from under the overriding plate producing strong vertical shear. In these cases SSTs

  6. Analogue modeling of the role of multi-level decollement layers on the geometry of orogenic wedge: an application to the Zagros Fold-Thrust Belt, SW Iran

    Science.gov (United States)

    Ghanadian, Mostafa; Faghih, Ali; Grasemann, Bernhard; Fard, Iraj Abdollahie; Maleki, Mehrdad

    2017-03-01

    The presence of evaporate and incompetent formations (i.e., decollement horizons) within the sedimentary sequence of fold-thrust belts can control their structural style and deformation evolution. In the present study, the influence of the decollement layers (e.g., basal and internal decollement layers) on the deformation style of several segments of the Zagros Fold-Thrust Belt (ZFTB), SW Iran (e.g., Fars Arc, Dezful Embayment, and Izeh Zone) was investigated using a series of analogue models of accretionary wedges. The study of seismic profiles to understand the structural evolution of these segments of the belt, where several decollement intervals acted as basal and internal decollements, is complemented by the analogue model results. The experimental results reveal that the thickness of the internal decollement layers influences the creation of fold-dominated or thrust-dominated deformations, respectively. Experimental models and seismic data highlight that incompetent layers act as barrier units against fault propagation (in-sequence and/or out-of-sequence faults) into overlying strata towards southwest by fore-deformation and control the rate of deformation propagation in the ZFTB. The presence of both the basal and internal decollement layers located at different stratigraphic levels is required to form disharmonic decollement folds in the foreland of the ZFTB. In addition, the geometry, spacing, activity, and propagation of faults as well as the topographic height of the critical wedges are directly controlled by low-frictional decollements (Geophys J Int, 165(1):336-356 2006; Geochem Geophys Geosyst, 14:1131-1155 2013). The seismic profiles of the ZFTB showed that in addition to lithological contrasts, the existence and activity of deep-seated and basement faults had a big impact on the structural styles of the region.

  7. An IBEM solution to the scattering of plane SH-waves by a lined tunnel in elastic wedge space

    Institute of Scientific and Technical Information of China (English)

    Zhongxian Liu; Lei Liu

    2015-01-01

    The indirect boundary element method (IBEM) is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space.According to the theory of single-layer potential,the scattered-wave field can be constructed by applying virtual uniform loads on the surface of lined tunnel and the nearby wedge surface.The densities of virtual loads can be solved by establishing equations through the continuity conditions on the interface and zero-traction conditions on free surfaces.The total wave field is obtained by the superposition of free field and scattered-wave field in elastic wedge space.Numerical results indicate that the IBEM can solve the diffraction of elastic wave in elastic wedge space accurately and efficiently.The wave motion feature strongly depends on the wedge angle,the angle of incidence,incident frequency,the location of lined tunnel,and material parameters.The waves interference and amplification effect around the tunnel in wedge space is more significant,causing the dynamic stress concentration factor on rigid tunnel and the displacement amplitude of flexible tunnel up to 50.0 and 17.0,respectively,more than double that of the case of half-space.Hence,considerable attention should be paid to seismic resistant or anti-explosion design of the tunnel built on a slope or hillside.

  8. Three-dimensional thermal structure of subduction zones. Effects of obliquity and curvature

    Energy Technology Data Exchange (ETDEWEB)

    Bengtson, A.K.; Van Keken, P.E. [Michigan Univ., Ann Arbor, MI (United States). Dept. of Earth and Environmental Sciences

    2012-07-01

    Quantifying the precise thermal structure of subduction zones is essential for understanding the nature of metamorphic dehydration reactions, arc volcanism, and intermediate depth seismicity. High resolution twodimensional (2-D) models have shown that the rheology of the mantle wedge plays a critical role and establishes strong temperature gradients in the slab. The influence of threedimensional (3-D) subduction zone geometry on thermal structure is however not yet well characterized. A common assumption for 2-D models is that the cross-section is taken normal to the strike of the trench with a corresponding velocity reduction in the case of oblique subduction, rather than taken parallel to velocity. A comparison between a full 3-D Cartesian model with oblique subduction and selected 2-D cross-sections demonstrates that the trench-normal crosssection provides a better reproduction of the slab thermal structure than the velocity-parallel cross-section. An exception is found in the case of a strongly curved trench, such as in the Marianas, where strong 3-D flow in the mantle wedge is generated. In this case