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Sample records for plate boundary offshore

  1. High-velocity basal sediment package atop oceanic crust, offshore Cascadia: Impacts on plate boundary processes and fluid migration

    Science.gov (United States)

    Peterson, D. E.; Keranen, K. M.

    2017-12-01

    Differences in fluid pressure and mechanical properties at megathrust boundaries in subduction zones have been proposed to create varying seismogenic behavior. In Cascadia, where large ruptures are possible but little seismicity occurs presently, new seismic transects across the deformation front (COAST cruise; Holbrook et al., 2012) image an unusually high-wavespeed sedimentary unit directly overlying oceanic crust. Wavespeed increases before sediments reach the deformation front, and the well-laminated unit, consistently of 1 km thickness, can be traced for 50 km beneath the accretionary prism before imaging quality declines. Wavespeed is modeled via iterative prestack time migration (PSTM) imaging and increases from 3.5 km/sec on the seaward end of the profile to >5.0 km/s near the deformation front. Landward of the deformation front, wavespeed is low along seaward-dipping thrust faults in the Quaternary accretionary prism, indicative of rapid dewatering along faults. The observed wavespeed of 5.5 km/sec just above subducting crust is consistent with porosity intersects the plate boundary at an oblique angle and changes the degree of hydration of the oceanic plate as it subducts within our area. Fluid flow out of oceanic crust is likely impeded by the low-porosity basal sediment package except along the focused thrust faults. Decollements are present at the top of oceanic basement, at the top of the high-wavespeed basal unit, and within sedimentary strata at higher levels; the decollement at the top of oceanic crust is active at the toe of the deformation front. The basal sedimentary unit appears to be mechanically strong, similar to observations from offshore Sumatra, where strongly consolidated sediments at the deformation front are interpreted to facilitate megathrust rupture to the trench (Hupers et al., 2017). A uniformly strong plate interface at Cascadia may inhibit microseismicity while building stress that is released in great earthquakes.

  2. Boundary Spanning in Offshored Information Systems Development Projects

    Science.gov (United States)

    Krishnan, Poornima

    2010-01-01

    Recent growth in offshore outsourcing of information systems (IS) services is accompanied by managing the offshore projects successfully. Much of the project failures can be attributed to geographic and organizational boundaries which create differences in culture, language, work patterns, and decision making processes among the offshore project…

  3. Structure of the la VELA Offshore Basin, Western Venezuela: AN Obliquely-Opening Rift Basin Within the South America-Caribbean Strike-Slip Plate Boundary

    Science.gov (United States)

    Blanco, J. M.; Mann, P.

    2015-12-01

    Bathymetric, gravity and magnetic maps show that the east-west trend of the Cretaceous Great Arc of the Caribbean in the Leeward Antilles islands is transected by an en echelon series of obliquely-sheared rift basins that show right-lateral offsets ranging from 20 to 40 km. The basins are 75-100 km in length and 20-30 km in width and are composed of sub-parallel, oblique slip normal faults that define deep, bathymetric channels that bound the larger islands of the Leeward Antilles including Aruba, Curacao and Bonaire. A single basin of similar orientation and structure, the Urumaco basin, is present to the southwest in the Gulf of Venezuela. We mapped structures and sedimentation in the La Vela rift basin using a 3D seismic data volume recorded down to 6 seconds TWT. The basin can be mapped from the Falcon coast where it is correlative with the right-lateral Adicora fault mapped onshore, and its submarine extension. To the southeast of the 3D survey area, previous workers have mapped a 70-km-wide zone of northeast-striking, oblique, right-lateral faults, some with apparent right-lateral offsets of the coastline. On seismic data, the faults vary in dip from 45 to 60 degrees and exhibit maximum vertical offsets of 600 m. The La Vela and other obliquely-opening rifts accommodate right-lateral shear with linkages to intervening, east-west-striking right-lateral faults like the Adicora. The zone of oblique rifts is restricted to the trend of the Great Arc of the Caribbean and may reflect the susceptiblity of this granitic basement to active shearing. The age of onset for the basins known from previous studies on the Leeward Antilles is early Miocene. As most of these faults occur offshore their potential to generate damaging earthquakes in the densely populated Leeward Antilles is not known.

  4. Iberian plate kinematics: A jumping plate boundary between Eurasia and Africa

    Science.gov (United States)

    Srivastava, S.P.; Schouten, Hans; Roest, W.R.; Klitgord, Kim D.; Kovacs, L.C.; Verhoef, J.; Macnab, R.

    1990-01-01

    THE rotation of Iberia and its relation to the formation of the Pyrenees has been difficult to decipher because of the lack of detailed sea-floor spreading data, although several models have been proposed1-7. Here we use detailed aeromagnetic measurements from the sea floor offshore of the Grand Banks of Newfoundland to show that Iberia moved as part of the African plate from late Cretaceous to mid-Eocene time, with a plate boundary extending westward from the Bay of Biscay. When motion along this boundary ceased, a boundary linking extension in the King's Trough to compression along the Pyrenees came into existence. Finally, since the late Oligocene, Iberia has been part of the Eurasian plate, with the boundary between Eurasia and Africa situated along the Azores-Gibraltar fracture zone.

  5. Geological and Structural evolution of the Eurasia Africa plate boundary in the Gulf of Cadiz Central Eastern Atlantic Sea.

    OpenAIRE

    D’Oriano, Filippo

    2010-01-01

    Iberia Africa plate boundary, cross, roughly W-E, connecting the eastern Atlantic Ocean from Azores triple junction to the Continental margin of Morocco. Relative movement between the two plate change along the boundary, from transtensive near the Azores archipelago, through trascurrent movement in the middle at the Gloria Fracture Zone, to transpressive in the Gulf of Cadiz area. This study presents the results of geophysical and geological analysis on the plate boundary area offshore Gibral...

  6. Crustal deformation and volcanism at active plate boundaries

    Science.gov (United States)

    Geirsson, Halldor

    Most of Earth's volcanoes are located near active tectonic plate boundaries, where the tectonic plates move relative to each other resulting in deformation. Likewise, subsurface magma movement and pressure changes in magmatic systems can cause measurable deformation of the Earth's surface. The study of the shape of Earth and therefore studies of surface deformation is called geodesy. Modern geodetic techniques allow precise measurements (˜1 mm accuracy) of deformation of tectonic and magmatic systems. Because of the spatial correlation between tectonic boundaries and volcanism, the tectonic and volcanic deformation signals can become intertwined. Thus it is often important to study both tectonic and volcanic deformation processes simultaneously, when one is trying to study one of the systems individually. In this thesis, I present research on crustal deformation and magmatic processes at active plate boundaries. The study areas cover divergent and transform plate boundaries in south Iceland and convergent and transform plate boundaries in Central America, specifically Nicaragua and El Salvador. The study is composed of four main chapters: two of the chapters focus on the magma plumbing system of Hekla volcano, Iceland and the plate boundary in south Iceland; one chapter focuses on shallow controls of explosive volcanism at Telica volcano, Nicaragua; and the fourth chapter focuses on co- and post-seismic deformation from a Mw = 7.3 earthquake which occurred offshore El Salvador in 2012. Hekla volcano is located at the intersection of a transform zone and a rift zone in Iceland and thus is affected by a combination of shear and extensional strains, in addition to co-seismic and co-rifting deformation. The inter-eruptive deformation signal from Hekla is subtle, as observed by a decade (2000-2010) of GPS data in south Iceland. A simultaneous inversion of this data for parameters describing the geometry and source characteristics of the magma chamber at Hekla, and

  7. Marginal inherited structures impact on the oblique convergent N American Plate/ Central Caribbean plate-boundary in the Northern Caribbean. The tectonic evolution since Miocene times based on Haiti data acquired onshore and offshore since 2012- a step toward an ADP Drilling Proposal (Haiti-DRILL).

    Science.gov (United States)

    Ellouz, N.; Hamon, Y.; Deschamps, R.; Battani, A.; Wessels, R.; Boisson, D.; Prepetit, C.; Momplaisir, R.

    2017-12-01

    Since Early Paleogene times, the North Caribbean plate is colliding obliquely with the south continental part of the old N. American Margins, which is represented by various segments from West to East, inherited from Jurassic times. Location, amount of displacement, rotation and the structural deformation of these margin segments, resulting from the dislocation of the continental N American margin, are not clearly yet established. At present, the plate limits are marked either by two left lateral faults west and inside Haiti (OSF in the North and EPGF in the South), oblique collision front (further west in Cuba), oblique subducted segments (to the East, Porto-Rico). From our recent works operated both offshore (Haiti-SIS and Haiti-BGF surveys 2012-2015) and onshore (field campaigns 2013-2017) in Haitian zone, the position of the present-day and paleo major limits have been redefined. These paleolimits have been reconstructed up to early Miocene times, based on: restoration of regional structural cross-sections, sedimentology and on paleoenvironement studies. In a preliminary way, we analyzed the complexity of the tectonic heritage with possible nature, heterogeneity of the crustal fragments and associated margins close to Haiti (age, structure, environment, location of the dislocated blocks through times) which profoundly impact the partitioning of the deformation along this complex transformed margin. The change in the structure wavelength, decollement level variations are primary constraints in the restoration of the main units and do impose a deep connection along specific segments either related to strike-slip or to splay faults. The asymmetry on the repartition of the fault activity tend to prove that the past motion related to "EPGF transfer zone" is mainly partitioned in Haiti to the North of the present-day EPGF position. At present, these results are still coherent with the distribution of the aftershoks registered after 2010, and with the present

  8. Vibration Analysis of Annular Sector Plates under Different Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Dongyan Shi

    2014-01-01

    Full Text Available An analytical framework is developed for the vibration analysis of annular sector plates with general elastic restraints along each edge of plates. Regardless of boundary conditions, the displacement solution is invariably expressed as a new form of trigonometric expansion with accelerated convergence. The expansion coefficients are treated as the generalized coordinates and determined using the Rayleigh-Ritz technique. This work allows a capability of modeling annular sector plates under a variety of boundary conditions and changing the boundary conditions as easily as modifying the material properties or dimensions of the plates. Of equal importance, the proposed approach is universally applicable to annular sector plates of any inclusion angles up to 2π. The reliability and accuracy of the current method are adequately validated through numerical examples.

  9. Introduction to Plate Boundaries and Natural Hazards

    NARCIS (Netherlands)

    Duarte, João C.; Schellart, Wouter P.

    2016-01-01

    A great variety of natural hazards occur on Earth, including earthquakes, volcanic eruptions, tsunamis, landslides, floods, fires, tornadoes, hurricanes, and avalanches. The most destructive of these hazards, earthquakes, tsunamis, and volcanic eruptions, are mostly associated with tectonic plate

  10. Plate boundary deformation of the Pacific plate. Two case studies. (1) Crustal structure of the northwestern Vizcaino block and Gorda escarpment, offshore northern California, and implications for postsubduction deformation of a paleoaccretionary margin. (2) A focused look at the Alpine fault, New Zealand: Seismicity, focal mechanisms and stress observations

    Science.gov (United States)

    Leitner, Beate

    Two examples of Pacific rim plate boundary deformation are presented. In the first part of the thesis crustal models are derived for the northwestern part of the Vizcaino block in California using marine seismic and gravity data collected by the Mendocino Triple Junction Seismic Experiment. A northwest-southeast trending kink in the Moho is imaged and interpreted to have formed under compression by reactivation of preexisting thrust faults in the paleoaccretionary prism at the seaward margin of the Vizcaino block. The study suggests that the deformation resulted from mainly north-south compression between the Pacific-Juan de Fuca plates across the Mendocino transform fault and predates late Pliocene Pacific-North America plate convergence. In the second part, 195 earthquakes recorded during the duration of the Southern Alps Passive Seismic Experiment (SAPSE) are analysed. Precise earthquake locations and focal mechanisms provide unprecedented detail of the seismotectonics in the central South Island. The short term (6 month) SAPSE seismicity is compared with long term (8 years) seismicity recorded by the New Zealand National Seismic network and the Lake Pukaki network. The seismicity rate of the Alpine fault is low, but comparable to locked sections of the San Andreas fault, with large earthquakes expected. Changes of the depth of the seismogenic zone, generally uniform at about 10--12 km, occur only localised over distances smaller than 30 km, suggesting that thermal perturbations must be of similar scale. This implies that the thermal effects of the uplift of the Southern Alps do not change the seismogenic depth significantly and are not in accordance with most of the present thermal models. Both the Hope and Porters Pass fault zones are seismically active and deformation is accommodated near the fault zones and in the adjacent crust. North of Mt Cook, a triangular shaped region along the Alpine fault is characterised by absence of earthquakes. We interpret this

  11. An Irrotational Flow Field That Approximates Flat Plate Boundary Conditions

    OpenAIRE

    Ruffa, Anthony A.

    2004-01-01

    An irrotational solution is derived for the steady-state Navier-Stokes equations that approximately satisfies the boundary conditions for flow over a finite flat plate. The nature of the flow differs substantially from boundary layer flow, with severe numerical difficulties in some regions.

  12. The Okhotsk Plate and the Eurasia-North America plate boundary zone.

    Science.gov (United States)

    Hindle, David; Mackey, Kevin

    2014-05-01

    The Eurasia-North America plate boundary zone transitions from spreading at rates of ~ 25mm/yr in the North Atlantic, to compression at rates of ~ 5mm/yr in the region of the Okhotsk plate. Because the pole of rotation between Eurasia and North America lies more or less on their mutual boundary, there is a linear change in rate along the boundary, and regions near the euler pole are subject to extremely low deformation rates. The Okhotsk - Eurasia - North America triple junction lies slightly south of the rotation pole, placing the Okhotsk plate entirely in a weakly contractional setting. Regions near the triple junction absorb 1mm/yr contraction. Further south, towards the shoreline of the Okhotsk sea, up to 5 mm/yr contraction may be absorbed within the plate. How shortening is accommodated across the boundary remains an open question. One possibility is wholesale extrusion of the entire Okhotsk plate (or possibly its northwestern corner) along two plate boundary strike slip faults (Eurasia-Okhostk and North America Okhotsk). The problem with this model is that the seismic record does not presently clearly support it, with the largest events distributed both within the plate interior and on its boundaries. This may suggest that instead, the Okhotsk plate, and particularly its north-western end, consists of a series of smaller blocks which shuffle against each other, partially accommodating extrusion, but also permitting some internal deformation and change of shape of the Okhotsk plate itself. We present analyses of the very sparse seismic record from the region, as well as geometric-kinematic, tectonic models of the possible deformation of northwest Okhotsk to try to better understand the different probabilities of how this slowly deforming plate boundary zone is behaving.

  13. A Possible Differentially Shortened Strike-slip Plate Boundary: the Okhotsk Plate Example.

    Science.gov (United States)

    Hindle, D.; Egorov, V.; Mackey, K. G.; Fujita, K.

    2004-12-01

    The Okhotsk plate has been postulated based on a combination of GPS geodetic inversions (REVEL1), seimsicity, geologic and lineament data. Lying between the North American and Eurasian plates, its northwestern corner would appear to be undergoing compression in a scissors motion between the two bounding plates. Extrusion tectonics along multiple, large strike-slip faults within the Okhotsk plate itself have been suggested to allow the escape of material away from the apex of Eurasia-North America. The plate boundary between Okhotsk and North America has been suggested to be diffuse, based on widely scattered minor seismicity. However, the large, left lateral, Ulakhan fault has also been suggested as a candidate plate boundary. We present field geological and geomorphological evidence of the partitioning of deformation between the Ulakhan fault, and several parallel and oblique, linked faults. The Ulakhan fault strand appears to have a maximum displacement of 24 km based on river valley offsets and closing large pull apart basins. Some of the displacement from the Ulakhan fault appears relayed into the plate margin along oblique trending, thrust/oblique slip faults. Estimated shortening over these faults is equivalent to the amount of shortening relayed into the plate margin from the plate boundary. There may be several thrust/oblique slip faults along the Ulakhan fault, which leads to the interesting situation of a segmented, strike-slip plate boundary being actively shortened in a margin parallel direction. This may be the result of postulated extrusion of the Okhotsk plate due to North America/Eurasia convergence. Such a situation would have important consequences for the interpretation of GPS data in a plate tectonic context.

  14. Vibration modes of a single plate with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Phamová L.

    2016-06-01

    Full Text Available This paper deals with free flexural vibration modes and natural frequencies of a thin plate with general boundary conditions — a simply supported plate connected to its surroundings with torsional springs. Vibration modes were derived on the basis of the Rajalingham, Bhat and Xistris approach. This approach was originally used for a clamped thin plate, so its adaptation was needed. The plate vibration function was usually expressed as a single partial differential equation. This partial differential equation was transformed into two ordinary differential equations that can be solved in the simpler way. Theoretical background of the computations is briefly described. Vibration modes of the supported plate with torsional springs are presented graphically and numerically for three different values of stiffness of torsional springs.

  15. Buckling transition and boundary layer in non-Euclidean plates.

    Science.gov (United States)

    Efrati, Efi; Sharon, Eran; Kupferman, Raz

    2009-07-01

    Non-Euclidean plates are thin elastic bodies having no stress-free configuration, hence exhibiting residual stresses in the absence of external constraints. These bodies are endowed with a three-dimensional reference metric, which may not necessarily be immersible in physical space. Here, based on a recently developed theory for such bodies, we characterize the transition from flat to buckled equilibrium configurations at a critical value of the plate thickness. Depending on the reference metric, the buckling transition may be either continuous or discontinuous. In the infinitely thin plate limit, under the assumption that a limiting configuration exists, we show that the limit is a configuration that minimizes the bending content, among all configurations with zero stretching content (isometric immersions of the midsurface). For small but finite plate thickness, we show the formation of a boundary layer, whose size scales with the square root of the plate thickness and whose shape is determined by a balance between stretching and bending energies.

  16. Swath sonar mapping of Earth's submarine plate boundaries

    Science.gov (United States)

    Carbotte, S. M.; Ferrini, V. L.; Celnick, M.; Nitsche, F. O.; Ryan, W. B. F.

    2014-12-01

    The recent loss of Malaysia Airlines flight MH370 in an area of the Indian Ocean where less than 5% of the seafloor is mapped with depth sounding data (Smith and Marks, EOS 2014) highlights the striking lack of detailed knowledge of the topography of the seabed for much of the worlds' oceans. Advances in swath sonar mapping technology over the past 30 years have led to dramatic improvements in our capability to map the seabed. However, the oceans are vast and only an estimated 10% of the seafloor has been mapped with these systems. Furthermore, the available coverage is highly heterogeneous and focused within areas of national strategic priority and community scientific interest. The major plate boundaries that encircle the globe, most of which are located in the submarine environment, have been a significant focus of marine geoscience research since the advent of swath sonar mapping. While the location of these plate boundaries are well defined from satellite-derived bathymetry, significant regions remain unmapped at the high-resolutions provided by swath sonars and that are needed to study active volcanic and tectonic plate boundary processes. Within the plate interiors, some fossil plate boundary zones, major hotspot volcanoes, and other volcanic provinces have been the focus of dedicated research programs. Away from these major tectonic structures, swath mapping coverage is limited to sparse ocean transit lines which often reveal previously unknown deep-sea channels and other little studied sedimentary structures not resolvable in existing low-resolution global compilations, highlighting the value of these data even in the tectonically quiet plate interiors. Here, we give an overview of multibeam swath sonar mapping of the major plate boundaries of the globe as extracted from public archives. Significant quantities of swath sonar data acquired from deep-sea regions are in restricted-access international archives. Open access to more of these data sets would

  17. Seismic gaps and plate tectonics: seismic potential for major boundaries

    Energy Technology Data Exchange (ETDEWEB)

    McCann, W R; Nishenko, S P; Sykes, L R; Krause, J

    1979-01-01

    The theory of plate tectonics provides a basic framework for evaluating the potential for future great earthquakes to occur along major plate boundaries. Along most of the transform and convergent plate boundaries considered in this paper, the majority of seismic slip occurs during large earthquakes, i.e., those of magnitude 7 or greater. The concepts that rupture zones, as delineated by aftershocks, tend to abut rather than overlap, and large events occur in regions with histories of both long-and short-term seismic quiescence are used in this paper to delineate major seismic gaps. The term seismic gap is taken to refer to any region along an active plate boundary that has not experienced a large thrust or strike-slip earthquake for more than 30 years. A region of high seismic potential is a seismic gap that, for historic or tectonic reasons, is considered likely to produce a large shock during the next few decades. The seismic gap technique provides estimates of the location, size of future events and origin time to within a few tens of years at best. The accompanying map summarizes six categories of seismic potential for major plate boundaries in and around the margins of the Pacific Ocean and the Caribbean, South Sandwich and Sunda (Indonesia) regions for the next few decades. These six categories are meant to be interpreted as forecasts of the location and size of future large shocks and should not be considered to be predictions in which a precise estimate of the time of occurrence is specified. The categories of potential assigned here provide a rationale for assigning priorities for instrumentation, for future studies aimed at predicting large earthquakes and for making estimates of tsunami potential.

  18. Stability Boundaries for Offshore Wind Park Distributed Voltage Control

    DEFF Research Database (Denmark)

    Gryning, Mikkel P.S.; Wu, Qiuwei; Kocewiak, Lukasz

    2017-01-01

    pilot control. Using data from the actual wind power plant, all stabilizing subsystem voltage proportional-integral controller parameters are first characterized based on their Hurwitz signature. Inner loop current control is then designed using Internal Mode Control principles, and guidelines for feed......In order to identify mechanisms causing slow reactive power oscillations observed in an existing offshore wind power plant, and be able to avoid similar events in the future, voltage control is studied in this paper for a plant with a static synchronous compensator, type-4 wind turbines and a park...... forward filter design are given to obtain required disturbance rejection properties. The paper contributes by providing analytical relations between power plant control, droop, sampling time, electrical parameters and voltage control characteristics, and by assessing frequencies and damping of reactive...

  19. Global plate boundary evolution and kinematics since the late Paleozoic

    Science.gov (United States)

    Matthews, Kara J.; Maloney, Kayla T.; Zahirovic, Sabin; Williams, Simon E.; Seton, Maria; Müller, R. Dietmar

    2016-11-01

    Many aspects of deep-time Earth System models, including mantle convection, paleoclimatology, paleobiogeography and the deep Earth carbon cycle, require high-resolution plate motion models that include the evolution of the mosaic of plate boundaries through time. We present the first continuous late Paleozoic to present-day global plate model with evolving plate boundaries, building on and extending two previously published models for the late Paleozoic (410-250 Ma) and Mesozoic-Cenozoic (230-0 Ma). We ensure continuity during the 250-230 Ma transition period between the two models, update the absolute reference frame of the Mesozoic-Cenozoic model and add a new Paleozoic reconstruction for the Baltica-derived Alexander Terrane, now accreted to western North America. This 410-0 Ma open access model provides a framework for deep-time whole Earth modelling and acts as a base for future extensions and refinement. We analyse the model in terms of the number of plates, predicted plate size distribution, plate and continental root mean square (RMS) speeds, plate velocities and trench migration through time. Overall model trends share many similarities to those for recent times, which we use as a first order benchmark against which to compare the model and identify targets for future model refinement. Except for during the period 260-160 Ma, the number of plates (16-46) and ratio of "large" plates (≥ 107.5 km2) to smaller plates ( 2.7-6.6) are fairly similar to present-day values (46 and 6.6, respectively), with lower values occurring during late Paleozoic assembly and growth of Pangea. This temporal pattern may also reflect difficulties in reconstructing small, now subducted oceanic plates further back in time, as well as whether a supercontinent is assembling or breaking up. During the 260-160 Ma timeframe the model reaches a minima in the number of plates, in contrast to what we would expect during initial Pangea breakup and thus highlighting the need for refinement

  20. Defects and boundary layers in non-Euclidean plates

    International Nuclear Information System (INIS)

    Gemmer, J A; Venkataramani, S C

    2012-01-01

    We investigate the behaviour of non-Euclidean plates with constant negative Gaussian curvature using the Föppl–von Kármán reduced theory of elasticity. Motivated by recent experimental results, we focus on annuli with a periodic profile. We prove rigorous upper and lower bounds for the elastic energy that scales like the thickness squared. In particular we show that are only two types of global minimizers—deformations that remain flat and saddle shaped deformations with isolated regions of stretching near the edge of the annulus. We also show that there exist local minimizers with a periodic profile that have additional boundary layers near their lines of inflection. These additional boundary layers are a new phenomenon in thin elastic sheets and are necessary to regularize jump discontinuities in the azimuthal curvature across lines of inflection. We rigorously derive scaling laws for the width of these boundary layers as a function of the thickness of the sheet. (paper)

  1. Structure of the Lithosphere-Asthenosphere Boundary Onshore and Offshore the California Continental Margin from Three-Dimensional Seismic Anisotropy

    Science.gov (United States)

    Gomez, C. D.; Escobar, L., Sr.; Rathnayaka, S.; Weeraratne, D. S.; Kohler, M. D.

    2016-12-01

    The California continental margin, a major transform plate boundary in continental North America, is the locus of complex tectonic stress fields that are important in interpreting both remnant and ongoing deformational strain. Ancient subduction of the East Pacific Rise spreading center, the rotation and translation of tectonic blocks and inception of the San Andreas fault all contribute to the dynamic stress fields located both onshore and offshore southern California. Data obtained by the ALBACORE (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) and the CISN (California Integrated Seismic Network) seismic array are analyzed for azimuthal anisotropy of Rayleigh waves from 80 teleseismic events at periods 16 - 78 s. Here we invert Rayleigh wave data for shear wave velocity structure and three-dimensional seismic anisotropy in the thee regions designated within the continental margin including the continent, seafloor and California Borderlands. Preliminary results show that seismic anisotropy is resolved in multiple layers and can be used to determine the lithosphere-asthenosphere boundary (LAB) in offshore and continental regions. The oldest seafloor in our study at age 25-35 Ma indicates that the anisotropic transition across the LAB occurs at 73 km +/- 25 km with the lithospheric fast direction oriented WNW-ESE, consistent with current Pacific plate motion direction. The continent region west of the San Andreas indicates similar WNW-ESE anisotropy and LAB depth. Regions east of the San Andreas fault indicate NW-SE anisotropy transitioning to a N-S alignment at 80 km depth north of the Garlock fault. The youngest seafloor (15 - 25 Ma) and outer Borderlands indicate a more complex three layer fabric where shallow lithospheric NE-SW fast directions are perpendicular with ancient Farallon subduction arc, a mid-layer with E-W fast directions are perpendicular to remnant fossil fabric, and the deepest layer

  2. Turbulent thermal boundary layer on a permeable flat plate

    International Nuclear Information System (INIS)

    Vigdorovich, I. I.

    2007-01-01

    Scaling laws are established for the profiles of temperature, turbulent heat flux, rms temperature fluctuation, and wall heat transfer in the turbulent boundary layer on a flat plate with transpiration. In the case of blowing, the temperature distribution represented in scaling variables outside the viscous sublayer has a universal form known from experimental data for flows over impermeable flat plates. In the case of suction, the temperature distribution is described by a one-parameter family of curves. A universal law of heat transfer having the form of a generalized Reynolds analogy provides a basis for representation of the heat flux distributions corresponding to different Reynolds numbers and transpiration velocities in terms of a function of one variable. The results are obtained without invoking any special closure hypotheses

  3. Two-media boundary layer on a flat plate

    OpenAIRE

    Nikolay Ilyich Klyuev; Asgat Gatyatovich Gimadiev; Yuriy Alekseevich Kryukov

    2014-01-01

    The present paper provides a solution to the problem of a flow over a flat semi-infinite plate set at an angle to the horizon, and having a thin liquid film on its surface by external airflow. The film is formed by extrusion of liquid from the porous wall. The paper proposes a mathematical model of a two-media boundary layer flow. The main characteristics of the flow to a zero and a first approximation are determined. A drop of frictional stress is obtained.

  4. Boundary layer on a flat plate with suction

    International Nuclear Information System (INIS)

    Favre, A.; Dumas, R.; Verollet, E.

    1961-01-01

    This research done in wind tunnel concerns the turbulent boundary layer of a porous flat plate with suction. The porous wall is 1 m long and begins 1 m downstream of the leading edge. The Reynolds number based on the boundary layer thickness is of the order of 16.300. The suction rate defined as the ratio of the velocity perpendicular to the wall to the external flow velocity ranges from 0 to 2 per cent. The pressure gradient can be controlled. The mean velocity profiles have been determined for various positions and suction rates by means of total pressure probes together with the intensities of the turbulent velocity fluctuations components, energy spectra and correlations by means of hot wire anemometers, spectral analyser and correlator. The stream lines, the values of the viscous and turbulent shear stresses, of the local wall friction, of the turbulent energy production term, with some information on the dissipation of the energy have been derived from these measurements. For these data the integral of equation of continuity in boundary layer have been drawn. The suction effects on the boundary layer are important. The suction thoroughly alters the mean velocity profiles by increasing the viscous shear stresses near the wall and decreasing them far from the wall, it diminishes the longitudinal and transversal turbulence intensities, the turbulent shear stresses, and the production of energy of turbulence. These effects are much stressed in the inner part of the boundary layer. On the other hand the energy spectra show that the turbulence scale is little modified, the boundary layer thickness being not much diminished by the suction. The suction effects can be appreciated by comparing twice the suction rate to the wall friction coefficient (assumed airtight), quite noticeable as soon as the rate is about unity, they become very important when it reaches ten. (author) [fr

  5. A Plate Tectonic Model for the Neoproterozoic with Evolving Plate Boundaries

    Science.gov (United States)

    Merdith, Andrew; Collins, Alan; Williams, Simon; Pisarevsky, Sergei; Müller, Dietmar

    2017-04-01

    The Neoproterozoic was dominated by the formation of the supercontinent Rodinia, its break-up and the subsequent amalgamation of Gondwana, during which, the planet experienced large climatic variations and the emergence of complex life. Here we present a topological plate model of the Neoproterozoic based on a synthesis of available geological and palaeomagnetic data. Subduction zones, which are well preserved in the geological record, are used as a proxy for convergent margins; evidence for mid-ocean ridges and transform motion is less clearly preserved, though passive margins are used as a proxy for spreading centres, and evidence for strike-slip motions are used to model transform boundaries. We find that the model presented here only predicts 70% of the total length of subduction active today, though it models similar lengths of both transform and divergent boundaries, suggesting that we have produced a conservative model and are probably underestimating the amount of subduction. Where evidence for convergent, divergent or transform motion is not preserved, we interpret the locations of plate boundaries based on the relative motions of cratonic crust as suggested through either palaeomagnetic data or the geological record. Using GPlates, we tie these boundaries together to generate a plate model that depicts the motion of tectonic plates through the Neoproterozoic. We omit India and South China from Rodinia completely, due to long-lived subduction preserved on margins of India and conflicting palaeomagnetic data for the Cryogenian, but tie them together due to similar Tonian aged accretionary patterns along their respective (present-day) north-western and northern margins, such that these two cratons act as a "lonely wanderer" for much of the Neoproterozoic, and form their own tectonic plate. We also introduce a Tonian-Cryogenian aged rotation of the Congo-São Francisco Craton relative to Rodinia to better fit palaeomagnetic data and account for thick passive

  6. Stress accumulation and release at complex transform plate boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Verdonck, D.; Furlong, K.P. (Pennsylvania State Univ., University Park (United States))

    1992-10-01

    Finite element methods are used to model the dynamics of deformation along complex transform plate boundaries, specifically the San Andreas fault system, California. Effects of mantle rheology and fault geometry on the stress buildup and release are investigated. No prior knowledge of the earthquake cycle time or amount of fault slip is assumed that the results suggest that the San Andreas fault slips at low shear stress (about 15 MPa). Although the maximum stress on the fault is 15 MPa, models with an upper mantle shear zone deforming entirely by dislocation creep accumulate stresses that exceed 100 MPa, a stress level high enough to drive localized dynamic recrystallization and a shift in dominant deformation mechanism to diffusion creep. Models in which the mantle shear zone deform locally by diffusion creep reach a dynamic steady state where lithospheric shear stresses never exceed the specified fault stress anywhere in the model and indicate that the strength of the upper mantle is an important parameter in the dynamics of plate boundary deformation. 17 refs.

  7. Major earthquakes occur regularly on an isolated plate boundary fault.

    Science.gov (United States)

    Berryman, Kelvin R; Cochran, Ursula A; Clark, Kate J; Biasi, Glenn P; Langridge, Robert M; Villamor, Pilar

    2012-06-29

    The scarcity of long geological records of major earthquakes, on different types of faults, makes testing hypotheses of regular versus random or clustered earthquake recurrence behavior difficult. We provide a fault-proximal major earthquake record spanning 8000 years on the strike-slip Alpine Fault in New Zealand. Cyclic stratigraphy at Hokuri Creek suggests that the fault ruptured to the surface 24 times, and event ages yield a 0.33 coefficient of variation in recurrence interval. We associate this near-regular earthquake recurrence with a geometrically simple strike-slip fault, with high slip rate, accommodating a high proportion of plate boundary motion that works in isolation from other faults. We propose that it is valid to apply time-dependent earthquake recurrence models for seismic hazard estimation to similar faults worldwide.

  8. Dike-induced contraction along oceanic and continental divergent plate boundaries

    KAUST Repository

    Trippanera, D.

    2014-10-28

    The axis of divergent plate boundaries shows extension fractures and normal faults at the surface. Here we present evidence of contraction along the axis of the oceanic ridge of Iceland and the continental Main Ethiopian Rift. Contraction is found at the base of the tilted hanging wall of dilational normal faults, balancing part of their extension. Our experiments suggest that these structures result from dike emplacement. Multiple dike injection induces subsidence above and uplift to the sides of the dikes; the transition in between is accommodated by reverse faults and subsequent peripheral inward dipping normal faults. Our results suggest that contraction is a direct product of magma emplacement along divergent plate boundaries, at various scales, marking a precise evolutionary stage and initiating part of the extensional structures (extension fractures and normal faults). Key Points Contraction along divergent plate boundaries results from dike emplacementContraction generates extensional structures along divergent plate boundariesSurface deformation along divergent plate boundaries may be magma induced

  9. Dike-induced contraction along oceanic and continental divergent plate boundaries

    KAUST Repository

    Trippanera, D.; Acocella, V.; Ruch, Joel

    2014-01-01

    The axis of divergent plate boundaries shows extension fractures and normal faults at the surface. Here we present evidence of contraction along the axis of the oceanic ridge of Iceland and the continental Main Ethiopian Rift. Contraction is found at the base of the tilted hanging wall of dilational normal faults, balancing part of their extension. Our experiments suggest that these structures result from dike emplacement. Multiple dike injection induces subsidence above and uplift to the sides of the dikes; the transition in between is accommodated by reverse faults and subsequent peripheral inward dipping normal faults. Our results suggest that contraction is a direct product of magma emplacement along divergent plate boundaries, at various scales, marking a precise evolutionary stage and initiating part of the extensional structures (extension fractures and normal faults). Key Points Contraction along divergent plate boundaries results from dike emplacementContraction generates extensional structures along divergent plate boundariesSurface deformation along divergent plate boundaries may be magma induced

  10. An EarthScope Plate Boundary Observatory Progress Report

    Science.gov (United States)

    Jackson, M.; Anderson, G.; Blume, F.; Walls, C.; Coyle, B.; Feaux, K.; Friesen, B.; Phillips, D.; Hafner, K.; Johnson, W.; Mencin, D.; Pauk, B.; Dittmann, T.

    2007-12-01

    UNAVCO is building and operating the Plate Boundary Observatory (PBO), part of the NSF-funded EarthScope project to understand the structure, dynamics, and evolution of the North American continent. When complete in October 2008, the 875 GPS, 103 strain and seismic, and 28 tiltmeters stations will comprise the largest integrated geodetic and seismic network in United States and the second largest in the world. Data from the PBO network will facilitate research into plate boundary deformation with unprecedented scope and detail. As of 1 September 2007, UNAVCO had completed 680 PBO GPS stations and had upgraded 89% of the planned PBO Nucleus stations. Highlights of the past year's work include the expansion of the Alaska subnetwork to 95 continuously-operating stations, including coverage of Akutan and Augustine volcanoes and reconnaissance for future installations on Unimak Island; the installation of nine new stations on Mt. St. Helens; and the arrival of 33 permits for station installations on BLM land in Nevada. The Augustine network provided critical data on magmatic and volcanic processes associated with the 2005-2006 volcanic crisis, and has expanded to a total of 11 stations. Please visit http://pboweb.unavco.org/?pageid=3 for further information on PBO GPS network construction activities. As of September 2007, 41 PBO borehole stations had been installed and three laser strainmeter stations were operating, with a total of 60 borehole stations and 4 laser strainmeters expected by October 2007. In response to direction from the EarthScope community, UNAVCO installed a dense network of six stations along the San Jacinto Fault near Anza, California; installed three of four planned borehole strainmeter stations on Mt. St. Helens; and has densified coverage of the Parkfield area. Please visit http://pboweb.unavco.org/?pageid=8 for more information on PBO strainmeter network construction progress. The combined PBO/Nucleus GPS network provides 350 GB of raw standard

  11. Crustal and upper mantle investigations of the Caribbean-South American plate boundary

    Science.gov (United States)

    Bezada, Maximiliano J.

    The evolution of the Caribbean --- South America plate boundary has been a matter of vigorous debate for decades and many questions remain unresolved. In this work, and in the framework of the BOLIVAR project, we shed light on some aspects of the present state and the tectonic history of the margin by using different types of geophysical data sets and techniques. An analysis of controlled-source traveltime data collected along a boundary-normal profile at ˜65°W was used to build a 2D P-wave velocity model. The model shows that the Caribbean Large Igenous Province is present offshore eastern Venezuela and confirms the uniformity of the velocity structure along the Leeward Antilles volcanic belt. In contrast with neighboring profiles, at this longitude we see no change in velocity structure or crustal thickness across the San Sebastian - El Pilar fault system. A 2D gravity modeling methodology that uses seismically derived initial density models was developed as part of this research. The application of this new method to four of the BOLIVAR boundary-normal profiles suggests that the uppermost mantle is denser under the South American continental crust and the island arc terranes than under the Caribbean oceanic crust. Crustal rocks of the island arc and extended island arc terranes of the Leeward Antilles have a relatively low density, given their P-wave velocity. This may be caused by low iron content, relative to average magmatic arc rocks. Finally, an analysis of teleseismic traveltimes with frequency-dependent kernels produced a 3D P-wave velocity perturbation model. The model shows the structure of the mantle lithosphere under the study area and clearly images the subduction of the Atlantic slab and associated partial removal of the lower lithosphere under northern South America. We also image the subduction of a section of the Caribbean plate under South America with an east-southeast direction. Both the Atlantic and Caribbean subducting slabs penetrate the

  12. MHD Boundary Layer Slip Flow and Heat Transfer over a Flat Plate

    International Nuclear Information System (INIS)

    Bhattacharyya, Krishnendu; Mukhopadhyay, Swati; Layek, G. C.

    2011-01-01

    An analysis of magnetohydrodynamic (MHD) boundary layer flow and heat transfer over a flat plate with slip condition at the boundary is presented. A complete self-similar set of equations are obtained from the governing equations using similarity transformations and are solved by a shooting method. In the boundary slip condition no local similarity occurs. Velocity and temperature distributions within the boundary layer are presented. Our analysis reveals that the increase of magnetic and slip parameters reduce the boundary layer thickness and also enhance the heat transfer from the plate. (fundamental areas of phenomenology(including applications))

  13. Eikonal Tomography of the Southern California Plate Boundary Region

    Science.gov (United States)

    Qiu, H.; Ben-Zion, Y.; Zigone, D.; Lin, F. C.

    2016-12-01

    We use eikonal tomography to derive directionally-dependent phase velocities of surface waves for the plate boundary region in southern CA sensitive to the approximate depth range 1-20 km. Seismic noise data recorded by 346 stations in the area provide a spatial coverage with 5-25 km typical station spacing and period range of 1-20 s. Noise cross-correlations are calculated for vertical component data recorded in year 2014. Rayleigh wave group and phase travel times between 2 and 13 sec period are derived for each station pair using frequency-time analysis. For each common station, all available phase travel time measurements with sufficient signal to noise ratio and envelope peak amplitude are used to construct a travel time map for a virtual source at the common station location. By solving the eikonal equation, both phase velocity and propagation direction are evaluated at each location for each virtual source. Isotropic phase velocities and 2-psi azimuthal anisotropy and their uncertainties are determined statistically using measurements from different virtual sources. Following the method of Barmin et al. (2001), group velocities are also inverted using all the group travel times that pass quality criteria. The obtained group and phase dispersions of Rayleigh waves are then inverted on a 6 x 6 km2 grid for local 1D piecewise shear wave velocity structures using the procedure of Herrmann (2013). The results agree well with previous observations of Zigone et al. (2015) in the overlapping area. Clear velocity contrasts and low velocity zones are seen for the San Andreas, San Jacinto, Elsinore and Garlock faults. We also find 2-psi azimuthal anisotropy with fast directions parallel to geometrically-simple fault sections. Details and updated results will be presented in the meeting.

  14. Performance Analysis of a Wind Turbine Driven Swash Plate Pump for Large Scale Offshore Applications

    International Nuclear Information System (INIS)

    Buhagiar, D; Sant, T

    2014-01-01

    This paper deals with the performance modelling and analysis of offshore wind turbine-driven hydraulic pumps. The concept consists of an open loop hydraulic system with the rotor main shaft directly coupled to a swash plate pump to supply pressurised sea water. A mathematical model is derived to cater for the steady state behaviour of entire system. A simplified model for the pump is implemented together with different control scheme options for regulating the rotor shaft power. A new control scheme is investigated, based on the combined use of hydraulic pressure and pitch control. Using a steady-state analysis, the study shows how the adoption of alternative control schemes in a the wind turbine-hydraulic pump system may result in higher energy yields than those from a conventional system with an electrical generator and standard pitch control for power regulation. This is in particular the case with the new control scheme investigated in this study that is based on the combined use of pressure and rotor blade pitch control

  15. A Case Study of Offshore Advection of Boundary Layer Rolls over a Stably Stratified Sea Surface

    Directory of Open Access Journals (Sweden)

    Nina Svensson

    2017-01-01

    Full Text Available Streaky structures of narrow (8-9 km high wind belts have been observed from SAR images above the Baltic Sea during stably stratified conditions with offshore winds from the southern parts of Sweden. Case studies using the WRF model and in situ aircraft observations indicate that the streaks originate from boundary layer rolls generated over the convective air above Swedish mainland, also supported by visual satellite images showing the typical signature cloud streets. The simulations indicate that the rolls are advected and maintained at least 30–80 km off the coast, in agreement with the streaks observed by the SAR images. During evening when the convective conditions over land diminish, the streaky structures over the sea are still seen in the horizontal wind field; however, the vertical component is close to zero. Thus advected feature from a land surface can affect the wind field considerably for long times and over large areas in coastal regions. Although boundary layer rolls are a well-studied feature, no previous study has presented results concerning their persistence during situations with advection to a strongly stratified boundary layer. Such conditions are commonly encountered during spring in coastal regions at high latitudes.

  16. Preparing the Plate Boundary Observatory GNSS Network for the Future

    Science.gov (United States)

    Austin, K. E.; Walls, C. P.; Dittman, T.; Mann, D.; Boyce, E. S.; Basset, A.; Woolace, A. C.; Turner, R.; Lawrence, S.; Rhoades, S.; Pyatt, C.; Willoughby, H.; Feaux, K.; Mattioli, G. S.

    2017-12-01

    The EarthScope Plate Boundary Observatory (PBO) GNSS network, funded by the NSF and operated by UNAVCO, is comprised of 1100 permanent GPS and GNSS stations spanning three principal tectonic regimes and is administered by distinct management. The GPS-only network was initially designed for daily data file downloads primarily for tectonic analysis. This low data volume requirement and circa-2004 IP-based cellular/VSat modems provided significant freedom for station placement and enabled science-targeted installation of stations in some of the most remote and geologically interesting areas. Community requests for high-rate data downloads for GNSS seismology, airborne LiDAR surveys, meteorological/GNSS/seismic real-time data flow and other demands, however, require significantly increased bandwidth beyond the 5-20 kB/s transfer rates that were needed as part of the original design. Since the close of construction in September 2008, PBO enhancements have been implemented through additional funding by the NSF (ARRA/Cascadia), NOAA, and NASA and in collaboration with stakeholders such as Caltrans, ODOT, Scripps, and the USGS. Today, only 18 of the original cell modems remain, with 601 upgraded cell modems providing 3G/4G/LTE data communications that support transfer rates ranging from 80-400 kB/s. Radio network expansion and upgrades continue to harden communications using both 2.4 GHz and 5.8 GHz radios. 78 VSAT and 5 manual download sites remain. PBO-wide the network capabilities for 1 Hz & 5 Hz downloads or low latency 1 Hz streaming are 85%, 80% and 65% of PBO stations, respectively, with 708 active 1 Hz streams. Vaisala meteorological instruments are located at 140 sites most of which stream GPS/Met data in real time. GPS-only receivers are being replaced with GNSS receivers and antennas. Today, there are 279 stations in the PBO network with either GLONASS enabled Trimble NetR9 or full GNSS constellation Septentrio PolaRx5 receivers. Just as the scale and

  17. How diking affects the longer-term structure and evolution of divergent plate boundaries

    KAUST Repository

    Trippanera, Daniele; Acocella, Valerio; Ruch, Joel; Rivalta, Eleonora

    2015-01-01

    Recurrent diking episodes along divergent plate boundaries, as at Dabbahu (2005, Afar) or at Bardarbunga (2014, Iceland) , highlight the possibility to have m-wide opening in a short time (days to weeks). This suggests a prominent role of magma

  18. The limitations on applying classical thin plate theory to thin annular plates clamped on the inner boundary

    Directory of Open Access Journals (Sweden)

    Daniel W. Zietlow

    2012-12-01

    Full Text Available The experimentally measured resonance frequencies of a thin annular plate with a small ratio of inner to outer radii and clamped on the inner boundary are compared to the predictions of classical thin-plate (CTP theory and a finite-element (FE model. The results indicate that, contrary to the conclusions presented in a number of publications, CTP theory does not accurately predict the frequencies of a relatively small number of resonant modes at lower frequencies. It is shown that these inaccuracies are attributable to shear deformations, which are thought to be negligible in thin plates and are neglected in CTP theory. Of particular interest is the failure of CTP theory to accurately predict the resonance frequency of the lowest vibrational mode, which was shifted approximately 30% by shear motion at the inner boundary.

  19. The stably stratified internal boundary layer for steady and diurnally varying offshore flow

    Science.gov (United States)

    Garratt, J. R.

    1987-03-01

    A two-dimensional numerical mesoscale model is used to investigate the internal structure and growth of the stably stratified internal boundary layer (IBL) beneath warm, continental air flowing over a cooler sea. Two situations are studied — steady-state and diurnally varying offshore flow. In the steady-state case, vertical profiles of mean quantities and eddy diffusion coefficients ( K) within the IBL show small, but significant, changes with increasing distance from the coast. The top of the IBL is well defined, with large vertical gradients within the layer and a maximum in the coast-normal wind component near the top. Well away from the coast, turbulence, identified by non-zero K, decreases to insignificant levels near the top of the IBL; the IBL itself is characterised by a critical value of the layer-flux Richardson number equal to 0.18. The overall behaviour of the mean profiles is similar to that found in the horizontally homogeneous stable boundary layer over land. A simple physical model is used to relate the depth of the layer h to several relevant physical parameters viz., x, the distance from the coast and U, the large-scale wind (both normal to the coastline) and gδθ/θ, Δθ being the temperature difference between continental mixed-layer air and sea surface, θ is the mean potential temperature and g is the acceleration due to gravity. Excellent agreement with the numerical results is found, with h = 0.014 x 1/2 U ( gδθ/θ)-1/2. In the diurnally varying case, the mean profiles within the IBL show only small differences from the steady-state case, although diurnal variations, particularly in the wind maximum, are evident within a few hundred kilometres of the coast. A mesoscale circulation normal to the coast, and superimposed upon the mean offshore flow, develops seawards of the coastline with maximum vertical velocities about sunset, of depth about 2 km and horizontal scale ≈ 500 km. The circulation is related to the advection, and

  20. Heat conduction in a plate-type fuel element with time-dependent boundary conditions

    International Nuclear Information System (INIS)

    Faya, A.J.G.; Maiorino, J.R.

    1981-01-01

    A method for the solution of boundary-value problems with variable boundary conditions is applied to solve a heat conduction problem in a plate-type fuel element with time dependent film coefficient. The numerical results show the feasibility of the method in the solution of this class of problems. (Author) [pt

  1. The influence of plate thickness on the welding residual stresses from submerged arc welding in offshore steel structures

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

    2017-01-01

    Welding-induced residual tensile stresses and distortion have become a major concern in relation to the structural integrity of welded structures within the offshore wind industry. The stresses have a negative impact on the integrity of the welded joint, as they promote distortion, reduce fatigue...... leading to a better understanding of the distribution and development of the welding residual stresses. This can later be used to optimize the fatigue design, providing a more efficient and improved design. In this context, the current research is expected to benefit the offshore industry by leading...... to an improved design, which consequently may be included in future norms and standards. Submerged Arc Welding (SAW) was used to make a fully penetrated butt weld in 10 mm and 40 mm thick steel plates with the same welding parameters as used in the production procedures. The base material is thermomechanical hot...

  2. Simulating faults and plate boundaries with a transversely isotropic plasticity model

    Science.gov (United States)

    Sharples, W.; Moresi, L. N.; Velic, M.; Jadamec, M. A.; May, D. A.

    2016-03-01

    In mantle convection simulations, dynamically evolving plate boundaries have, for the most part, been represented using an visco-plastic flow law. These systems develop fine-scale, localized, weak shear band structures which are reminiscent of faults but it is a significant challenge to resolve the large- and the emergent, small-scale-behavior. We address this issue of resolution by taking into account the observation that a rock element with embedded, planar, failure surfaces responds as a non-linear, transversely isotropic material with a weak orientation defined by the plane of the failure surface. This approach partly accounts for the large-scale behavior of fine-scale systems of shear bands which we are not in a position to resolve explicitly. We evaluate the capacity of this continuum approach to model plate boundaries, specifically in the context of subduction models where the plate boundary interface has often been represented as a planar discontinuity. We show that the inclusion of the transversely isotropic plasticity model for the plate boundary promotes asymmetric subduction from initiation. A realistic evolution of the plate boundary interface and associated stresses is crucial to understanding inter-plate coupling, convergent margin driven topography, and earthquakes.

  3. Reorganization of convergent plate boundaries. Geologica Ultraiectina (340)

    NARCIS (Netherlands)

    Baes, M.

    2011-01-01

    It is still unclear where a subduction is initiated and what are the responsible mechanisms involved in subduction initiation process. Understanding of subduction initiation will advance our knowledge of how and when plate tectonics started on Earth. Another issue concerning the subduction process

  4. Prandtl boundary layer expansions of steady Navier-Stokes flows over a moving plate

    OpenAIRE

    Guo, Yan; Nguyen, Toan T.

    2014-01-01

    This paper concerns the validity of the Prandtl boundary layer theory in the inviscid limit for steady incompressible Navier-Stokes flows. The stationary flows, with small viscosity, are considered on $[0,L]\\times \\mathbb{R}_{+}$, assuming a no-slip boundary condition over a moving plate at $y=0$. We establish the validity of the Prandtl boundary layer expansion and its error estimates.

  5. Role of Transtension in Rifting at the Pacific-North America Plate Boundary

    Science.gov (United States)

    Stock, J. M.

    2011-12-01

    Transtensional plate motion can be accommodated either in a localized zone of transtensional rifting or over a broader region. Broader zones of deformation can be classified either as diffuse deformation or strain partitioning (one or more major strike-slip shear zones geographically offset from a region of a extensional faulting). The Pacific-North America plate boundary in southwestern North America was transtensional during much of its history and has exhibited the full range of these behaviors at different spatial scales and in different locations, as recorded by fault motions and paleomagnetic rotations. Here we focus on the northern Gulf of California part of the plate boundary (Upper and Lower Delfin basin segments), which has been in a zone of transtensional Pacific-North America plate boundary motion ever since the middle Miocene demise of adjacent Farallon-derived microplates. Prior to the middle Miocene, during the time of microplate activity, this sector of North America experienced basin-and-range normal faults (core complexes) in Sonora. However there is no evidence of continued extensional faulting nor of a Gulf-related topographic depression until after ca 12 Ma when a major ignimbrite (Tuff of San Felipe/ Ignimbrite of Hermosillo) was deposited across the entire region of the future Gulf of California rift in this sector. After 12 Ma, faults disrupted this marker bed in eastern Baja California and western Sonora, and some major NNW-striking right-lateral faults are inferred to have developed near the Sonoran coast causing offset of some of the volcanic facies. However, there are major tectonic rotations of the volcanic rocks in NE Baja California between 12 and 6 Ma, suggesting that the plate boundary motion was still occurring over a broad region. By contrast, after about 6 Ma, diminished rotations in latest Miocene and Pliocene volcanic rocks, as well as fault slip histories, show that plate boundary deformation became localized to a narrower

  6. Flat Plate Boundary Layer Stimulation Using Trip Wires and Hama Strips

    Science.gov (United States)

    Peguero, Charles; Henoch, Charles; Hrubes, James; Fredette, Albert; Roberts, Raymond; Huyer, Stephen

    2017-11-01

    Water tunnel experiments on a flat plate at zero angle of attack were performed to investigate the effect of single roughness elements, i.e., trip wires and Hama strips, on the transition to turbulence. Boundary layer trips are traditionally used in scale model testing to force a boundary layer to transition from laminar to turbulent flow at a single location to aid in scaling of flow characteristics. Several investigations of trip wire effects exist in the literature, but there is a dearth of information regarding the influence of Hama strips on the flat plate boundary layer. The intent of this investigation is to better understand the effects of boundary layer trips, particularly Hama strips, and to investigate the pressure-induced drag of both styles of boundary layer trips. Untripped and tripped boundary layers along a flat plate at a range of flow speeds were characterized with multiple diagnostic measurements in the NUWC/Newport 12-inch water tunnel. A wide range of Hama strip and wire trip thicknesses were used. Measurements included dye flow visualization, direct skin friction and parasitic drag force, boundary layer profiles using LDV, wall shear stress fluctuations using hot film anemometry, and streamwise pressure gradients. Test results will be compared to the CFD and boundary layer model results as well as the existing body of work. Conclusions, resulting in guidance for application of Hama strips in model scale experiments and non-dimensional predictions of pressure drag will be presented.

  7. Three-Dimensional Vibration Analysis of Rectangular Thick Plates on Pasternak Foundation with Arbitrary Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Huimin Liu

    2017-01-01

    Full Text Available This paper presents the first known vibration characteristic of rectangular thick plates on Pasternak foundation with arbitrary boundary conditions on the basis of the three-dimensional elasticity theory. The arbitrary boundary conditions are obtained by laying out three types of linear springs on all edges. The modified Fourier series are chosen as the basis functions of the admissible function of the thick plates to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges. The exact solution is obtained based on the Rayleigh–Ritz procedure by the energy functions of the thick plate. The excellent accuracy and reliability of current solutions are demonstrated by numerical examples and comparisons with the results available in the literature. In addition, the influence of the foundation coefficients as well as the boundary restraint parameters is also analyzed, which can serve as the benchmark data for the future research technique.

  8. Stress rotation across the Cascadia megathrust requires a weak subduction plate boundary at seismogenic depths

    Science.gov (United States)

    Li, Duo; McGuire, Jeffrey J.; Liu, Yajing; Hardebeck, Jeanne L.

    2018-01-01

    The Mendocino Triple Junction region is the most seismically active part of the Cascadia Subduction Zone. The northward moving Pacific plate collides with the subducting Gorda plate causing intense internal deformation within it. Here we show that the stress field rotates rapidly with depth across the thrust interface from a strike-slip regime within the subducting plate, reflecting the Pacific plate collision, to a thrust regime in the overriding plate. We utilize a dense focal mechanism dataset, including observations from the Cascadia Initiative ocean bottom seismograph experiment, to constrain the stress orientations. To quantify the implications of this rotation for the strength of the plate boundary, we designed an inversion that solves for the absolute stress tensors in a three-layer model subject to assumptions about the strength of the subducting mantle. Our results indicate that the shear stress on the plate boundary fault is likely no more than about ∼50 MPa at ∼20 km depth. Regardless of the assumed mantle strength, we infer a relatively weak megathrust fault with an effective friction coefficient of ∼0 to 0.2 at seismogenic depths. Such a low value for the effective friction coefficient requires a combination of high fluid pressures and/or fault-zone minerals with low inherent friction in the region where a great earthquake is expected in Cascadia.

  9. Stress rotation across the Cascadia megathrust requires a weak subduction plate boundary at seismogenic depths

    Science.gov (United States)

    Li, Duo; McGuire, Jeffrey J.; Liu, Yajing; Hardebeck, Jeanne L.

    2018-03-01

    The Mendocino Triple Junction region is the most seismically active part of the Cascadia Subduction Zone. The northward moving Pacific plate collides with the subducting Gorda plate causing intense internal deformation within it. Here we show that the stress field rotates rapidly with depth across the thrust interface from a strike-slip regime within the subducting plate, reflecting the Pacific plate collision, to a thrust regime in the overriding plate. We utilize a dense focal mechanism dataset, including observations from the Cascadia Initiative ocean bottom seismograph experiment, to constrain the stress orientations. To quantify the implications of this rotation for the strength of the plate boundary, we designed an inversion that solves for the absolute stress tensors in a three-layer model subject to assumptions about the strength of the subducting mantle. Our results indicate that the shear stress on the plate boundary fault is likely no more than about ∼50 MPa at ∼20 km depth. Regardless of the assumed mantle strength, we infer a relatively weak megathrust fault with an effective friction coefficient of ∼0 to 0.2 at seismogenic depths. Such a low value for the effective friction coefficient requires a combination of high fluid pressures and/or fault-zone minerals with low inherent friction in the region where a great earthquake is expected in Cascadia.

  10. Resolving plate structure across the seismogenic zone in Cascadia from onshore-offshore receiver function imaging

    Science.gov (United States)

    Audet, P.; Schaeffer, A. J.

    2017-12-01

    Studies of the forearc structure in the Cascadia subduction zone using teleseismic P-wave receiver function have resolved structures associated with deep fluid cycling, such as the basalt-to-eclogite reaction and fluid overpressure within the subducting oceanic crust, as well as the serpentinization of the forearc mantle wedge. Unfortunately, the updip extent of the over-pressured zone, and therefore the possible control on the transition from episodic slow slip to seismic slip, occurs offshore and is not resolved in those studies. The Cascadia Initiative (CI) has provided an opportunity to extend this work to the locked zone using teleseismic receiver functions from the deployment of a dense line of ocean-bottom seismograph stations offshore of Washington State, from the trench to the coastline. Here we calculate P-wave receiver functions using data from offshore (CI) and onshore (CAFE) broadband seismic stations. These data clearly show the various scattered phases associated with a dipping low-velocity layer that was identified in previous studies as the downgoing oceanic crust. These signals are difficult to untangle offshore because they arrive at similar times. We process receiver functions using a modified common-conversion point (CCP) stacking technique that uses a coherency filter to optimally stack images obtained from the three main scattered phases. The resulting image shows along-dip variations in the character of the seismic discontinuities associated with the top and bottom of the low-velocity layer. Combined with focal depth information of regular and low-frequency earthquakes, these variations may reflect changes in the material properties of the megathrust across the seismogenic zone in Cascadia.

  11. a Lattice Boltzmann Study of the 2d Boundary Layer Created by AN Oscillating Plate

    Science.gov (United States)

    Cappietti, L.; Chopard, B.

    We study the applicability of the Lattice Boltzmann Method (LBM) to simulate the 2D laminar boundary layer induced by an oscillating flat plate. We also investigate the transition to the disturbed laminar regime that occurs with a rough oscillating plate. The simulations were performed in two cases: first with a fluid otherwise at rest and second in presence of superimposed current. The generation of coherent vortex structures and their evolution are commented. The accuracy of the method was checked by comparisons with the exact analytical solution of the Navier-Stokes equations for the so-called Stokes' Second Problem. The comparisons show that LBM reproduces this time varying flow with first order accuracy. In the case of the wavy-plate, the results show that a mechanism of vortex-jet formations, low speed-streak and shear instability sustain a systems of stationary vortices outside the boundary layer. The vortex-jet takes place at the end of the decelerating phase whereas the boundary layer turns out to be laminar when the plate accelerates. In the presence of the superimposed current, the vortex-jet mechanism is still effective but the vortices outside the boundary layer are only present during part of the oscillating period. During the remaining part, the flow turns out to be laminar although a wave perturbation in the velocity field is present.

  12. What drives microplate motion and deformation in the northeastern Caribbean plate boundary region?

    NARCIS (Netherlands)

    van Benthem, S.A.C.; Govers, R.; Wortel, R.

    2014-01-01

    The north Caribbean plate boundary zone is a broad deformation zone with several fault systems and tectonic blocks that move with different velocities. The indentation by the Bahamas Platform (the “Bahamas Collision”) is generally invoked as a cause of this fragmentation. We propose that a second

  13. Tracking the India-Arabia Transform Plate Boundary during Paleogene Times.

    Science.gov (United States)

    Rodriguez, M.; Huchon, P.; Chamot-Rooke, N. R. A.; Fournier, M.; Delescluse, M.

    2014-12-01

    The Zagros and Himalaya mountain belts are the most prominent reliefs built by continental collision. They respectively result from Arabia and India collision with Eurasia. Convergence motions at mountain belts induced most of plate reorganization events in the Indian Ocean during the Cenozoic. Although critical for paleogeographic reconstructions, the way relative motion between Arabia and India was accommodated prior to the formation of the Sheba ridge in the Gulf of Aden remains poorly understood. The India-Arabia plate-boundary belongs to the category of long-lived (~90-Ma) oceanic transform faults, thus providing a good case study to investigate the role of major kinematic events over the structural evolution of a long-lived transform system. A seismic dataset crossing the Owen Fracture Zone, the Owen Basin, and the Oman Margin was acquired to track the past locations of the India-Arabia plate boundary. We highlight the composite age of the Owen Basin basement, made of Paleocene oceanic crust drilled on its eastern part, and composed of pre-Maastrichtian continental crust overlaid by Early Paleocene ophiolites on its western side. A major transform fault system crossing the Owen Basin juxtaposed these two slivers of lithosphere of different ages, and controlled the uplift of marginal ridges along the Oman Margin. This transform system deactivated ~40 Ma ago, coeval with the onset of ultra-slow spreading at the Carlsberg Ridge. The transform boundary then jumped to the edge of the present-day Owen Ridge during the Late Eocene-Oligocene period, before seafloor spreading began at the Sheba Ridge. This migration of the plate boundary involved the transfer of a part of the Indian oceanic lithosphere accreted at the Carlsberg Ridge to the Arabian plate. The episode of plate transfer at the India-Arabia plate boundary during the Late Eocene-Oligocene interval is synchronous with a global plate reorganization event corresponding to geological events at the Zagros and

  14. Numerical investigation of interactions between marine atmospheric boundary layer and offshore wind farm

    Science.gov (United States)

    Lyu, Pin; Chen, Wenli; Li, Hui; Shen, Lian

    2017-11-01

    In recent studies, Yang, Meneveau & Shen (Physics of Fluids, 2014; Renewable Energy, 2014) developed a hybrid numerical framework for simulation of offshore wind farm. The framework consists of simulation of nonlinear surface waves using a high-order spectral method, large-eddy simulation of wind turbulence on a wave-surface-fitted curvilinear grid, and an actuator disk model for wind turbines. In the present study, several more precise wind turbine models, including the actuator line model, actuator disk model with rotation, and nacelle model, are introduced into the computation. Besides offshore wind turbines on fixed piles, the new computational framework has the capability to investigate the interaction among wind, waves, and floating wind turbines. In this study, onshore, offshore fixed pile, and offshore floating wind farms are compared in terms of flow field statistics and wind turbine power extraction rate. The authors gratefully acknowledge financial support from China Scholarship Council (No. 201606120186) and the Institute on the Environment of University of Minnesota.

  15. A preliminary investigation of boundary-layer transition along a flat plate with adverse pressure gradient

    Science.gov (United States)

    Von Doenhoff, Albert E

    1938-01-01

    Boundary-layer surveys were made throughout the transition region along a smooth flat plate placed in an airstream of practically zero turbulence and with an adverse pressure gradient. The boundary-layer Reynolds number at the laminar separation point was varied from 1,800 to 2,600. The test data, when considered in the light of certain theoretical deductions, indicated that transition probably began with separation of the laminar boundary layer. The extent of the transition region, defined as the distance from a calculated laminar separation point to the position of the first fully developed turbulent boundary-layer profile, could be expressed as a constant Reynolds number run of approximately 70,000. Some speculations are presented concerning the application of the foregoing concepts, after certain assumptions have been made, to the problem of the connection between transition on the upper surface of an airfoil at high angles of attack and the maximum lift.

  16. Generalized wall function and its application to compressible turbulent boundary layer over a flat plate

    Science.gov (United States)

    Liu, J.; Wu, S. P.

    2017-04-01

    Wall function boundary conditions including the effects of compressibility and heat transfer are improved for compressible turbulent boundary flows. Generalized wall function formulation at zero-pressure gradient is proposed based on coupled velocity and temperature profiles in the entire near-wall region. The parameters in the generalized wall function are well revised. The proposed boundary conditions are integrated into Navier-Stokes computational fluid dynamics code that includes the shear stress transport turbulence model. Numerical results are presented for a compressible boundary layer over a flat plate at zero-pressure gradient. Compared with experimental data, the computational results show that the generalized wall function reduces the first grid spacing in the directed normal to the wall and proves the feasibility and effectivity of the generalized wall function method.

  17. Evidence of displacement-driven maturation along the San Cristobal Trough transform plate boundary

    Science.gov (United States)

    Neely, James S.; Furlong, Kevin P.

    2018-03-01

    The San Cristobal Trough (SCT), formed by the tearing of the Australia plate as it subducts under the Pacific plate near the Solomon Islands, provides an opportunity to study the transform boundary development process. Recent seismicity (2013-2016) along the 280 km long SCT, known as a Subduction-Transform Edge Propagator (STEP) fault, highlights the tearing process and ongoing development of the plate boundary. The region's earthquakes reveal two key characteristics. First, earthquakes at the western terminus of the SCT, which we interpret to indicate the Australia plate tearing, display disparate fault geometries. These events demonstrate that plate tearing is accommodated via multiple intersecting planes rather than a single through-going fault. Second, the SCT hosts sequences of Mw ∼7 strike-slip earthquakes that migrate westward through a rapid succession of events. Sequences in 1993 and 2015 both began along the eastern SCT and propagated west, but neither progression ruptured into or nucleated a large earthquake within the region near the tear. Utilizing b-value and Coulomb Failure Stress analyses, we examine these along-strike variations in the SCT's seismicity. b-Values are highest along the youngest, western end of the SCT and decrease with increasing distance from the tear. This trend may reflect increasing strain localization with increasing displacement. Coulomb Failure Stress analyses indicate that the stress conditions were conducive to continued western propagation of the 1993 and 2015 sequences suggesting that the unruptured western SCT may have fault geometries or properties that inhibit continued rupture. Our results indicate a displacement-driven fault maturation process. The multi-plane Australia plate tearing likely creates a western SCT with diffuse strain accommodated along a network of disorganized faults. After ∼90 km of cumulative displacement (∼900,000 yr of plate motion), strain localizes and faults align, allowing the SCT to host

  18. The atmospheric boundary layer over land and sea: Focus on the off-shore Southern Baltic and Southern North Sea region

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling

    Lecture notes for a short course on the ideal atmospheric boundary layer and its characteristics for different types of real boundary layers, aiming at a discussion of the coastal conditions at the Southern Baltic and North Sea region. The notes are aimed at young scientists (e.g. PhD students......) that study the physics of the atmospheric boundary layer with the purpose of applying this knowledge for remote sensing techniques within offshore wind energy....

  19. Heat transfer enhancement in a turbulent natural convection boundary layer along a vertical flat plate

    International Nuclear Information System (INIS)

    Tsuji, Toshihiro; Kajitani, Tsuyoshi; Nishino, Tatsuhiko

    2007-01-01

    An experimental study on heat transfer enhancement for a turbulent natural convection boundary layer in air along a vertical flat plate has been performed by inserting a long flat plate in the spanwise direction (simple heat transfer promoter) and short flat plates aligned in the spanwise direction (split heat transfer promoter) with clearances into the near-wall region of the boundary layer. For a simple heat transfer promoter, the heat transfer coefficients increase by a peak value of approximately 37% in the downstream region of the promoter compared with those in the usual turbulent natural convection boundary layer. It is found from flow visualization and simultaneous measurements of the flow and thermal fields with hot- and cold-wires that such increase of heat transfer coefficients is mainly caused by the deflection of flows toward the outer region of the boundary layer and the invasion of low-temperature fluids from the outer region to the near-wall region with large-scale vortex motions riding out the promoter. However, heat transfer coefficients for a split heat transfer promoter exhibit an increase in peak value of approximately 60% in the downstream region of the promoter. Flow visualization and PIV measurements show that such remarkable heat transfer enhancement is attributed to longitudinal vortices generated by flows passing through the clearances of the promoter in addition to large-scale vortex motions riding out the promoter. Consequently, it is concluded that heat transfer enhancement of the turbulent natural convection boundary layer can be substantially achieved in a wide area of the turbulent natural convection boundary layer by employing multiple column split heat transfer promoters. It may be expected that the heat transfer enhancement in excess of approximately 40% can be accomplished by inserting such promoters

  20. Using GPS, tide gauge and altimetry data to constrain subduction parameters at the Vanuatu plate boundary.

    Science.gov (United States)

    Ballu, V.; Bouin, M.; Baillard, C.; Calmant, S.; Pelletier, B.; Crawford, W. C.; Kanas, T.; Garaebiti, E.

    2012-12-01

    two offshore sites using absolute pressure gauges. The sites - Wusi and Sabine Banks - are installed beneath altimetry satellite tracks, Wusi Bank on the over-riding plate and Sabine Bank on the subducting plate. The difference in the pressure records between the sites shows that Wusi Bank subsides by 11 +/- 3 mm/yr with respect to Sabine Bank. We combined the water depths derived from the pressure measurements with altimetry-derived sea-surface heights to tie these heights to a global reference frame: Wusi Bank subsides and Sabine Bank's vertical motion is near zero. Using a 2D elastic model and a finite-element code, we used the gradient of vertical deformation between the coast and the Wusi Bank site to discriminate between possible locked zone geometries. The best simple approximation is a 25° dipping, 30 km long fully locked zone, indicating that stress is currently accumulating west of Santo, Central Vanuatu. The movement of Wusi Bank is a key factor in constraining the dip and length of the locked zone, demonstrating the importance of offshore geodesy measurements.

  1. Numerical analysis of viscoelastic boundary layers : the case of plate withdrawal in a Maxwellian fluid

    International Nuclear Information System (INIS)

    Sadeghy, K.; Sharifi, M.

    2002-01-01

    The effect of a fluid's elasticity on the characteristics of its boundary layer was investigated in this work. A viscoelastic fluid of Maxwellian type was selected for this purpose and the flow induced in this fluid by a plate withdrawing at a constant velocity was studied. Conventional boundary layer assumptions were invoked to reduce the equations of motion to a simple form incorporating an elastic term in addition to the familiar inertial, viscous and pressure terms. It was shown that for elastic effects to be of an importance in a boundary layer, the fluid's relaxation time should be of an order much larger than its kinematic viscosity. By introducing a stream function, the governing equation was transformed into a nonlinear ODE with x-coordinate still appearing in the equation demonstrating that no similarity solution existed for this flow. The resulting equation was then solved numerically for Deborah numbers as large as 1.0. The results showed a marked formation of boundary layer adjacent to a moving wall for a Maxwellian fluid. The boundary layer thickness and the wall shear stress were found to scale with fluid's elasticity - both decreasing the higher the fluid's elasticity. It is thus anticipated that in free coating processes, the force required to impart a constant velocity to a withdrawing belt or plate would be lower if fluid's elasticity is significant. (author)

  2. Shallow very-low-frequency earthquakes accompanied with slow slip event along the plate boundary of the Nankai trough

    Science.gov (United States)

    Nakano, M.; Hori, T.; Araki, E.; Kodaira, S.; Ide, S.

    2017-12-01

    Recent improvements of seismic and geodetic observations have revealed the existence of a new family of slow earthquakes occurring along or close to the plate boundary worldwide. In the viewpoint of the characteristic time scales, the slow earthquakes can be classified into several groups as low-frequency tremor or tectonic tremor (LFT) dominated in several hertz, very-low-frequency earthquake (VLFE) dominated in 10 to 100 s, and short- and long-term slow-slip event (SSE) with durations of days to years. In many cases, these slow earthquakes are accompanied with other types of slow events. However, the events occurring offshore, especially beneath the toe of accretionary prism, are poorly understood because of the difficulty to detect signals. Utilizing the data captured from oceanfloor observation networks which many efforts have recently been taken to develop is necessary to improve our understandings for these events. Here, we investigated CMT analysis of shallow VLFEs using data obtained from DONET oceanfloor observation networks along the Nankai trough, southwest of Japan. We found that shallow VLFEs have almost identical history of moment release with that of synchronous SSE which occurred at the same region recently found by Araki et al. (2017). VLFE sources show updip migrations during the activity, coincident with the migration of SSE source. From these findings we conclude that these slow events share the same fault slip, and VLFE represent high-frequency fluctuations of slip during SSE. This result imply that shallow SSE along the plate interface would have occurred in the background during the shallow VLFE activities repeatedly observed along the Nankai trough, but the SSE was not reported because of difficult detections.

  3. Alternate model of Chladni figures for the circular homogenous thin plate case with open boundaries

    International Nuclear Information System (INIS)

    Trejo-Mandujano, H A; Mijares-Bernal, G; Ordoñez-Casanova, E G

    2015-01-01

    The wave equation is a direct but a complex approach to solve analytically for the Chladni figures, mainly because of the complications that non-smooth and open boundary conditions impose. In this paper, we present an alternate solution model based on the principle of Huygens-Fresnel and on the ideas of Bohr for the hydrogen atom. The proposed model has been implemented numerically and compared, with good agreement, to our own experimental results for the case of a thin homogenous circular plate with open boundaries

  4. Experimental Results from a Flat Plate, Turbulent Boundary Layer Modified for the Purpose of Drag Reduction

    Science.gov (United States)

    Elbing, Brian R.

    2006-11-01

    Recent experiments on a flat plate, turbulent boundary layer at high Reynolds numbers (>10^7) were performed to investigate various methods of reducing skin friction drag. The methods used involved injecting either air or a polymer solution into the boundary layer through a slot injector. Two slot injectors were mounted on the model with one located 1.4 meters downstream of the nose and the second located 3.75 meters downstream. This allowed for some synergetic experiments to be performed by varying the injections from each slot and comparing the skin friction along the plate. Skin friction measurements were made with 6 shear stress sensors flush mounted along the stream-wise direction of the model.

  5. Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake.

    Science.gov (United States)

    Schurr, Bernd; Asch, Günter; Hainzl, Sebastian; Bedford, Jonathan; Hoechner, Andreas; Palo, Mauro; Wang, Rongjiang; Moreno, Marcos; Bartsch, Mitja; Zhang, Yong; Oncken, Onno; Tilmann, Frederik; Dahm, Torsten; Victor, Pia; Barrientos, Sergio; Vilotte, Jean-Pierre

    2014-08-21

    On 1 April 2014, Northern Chile was struck by a magnitude 8.1 earthquake following a protracted series of foreshocks. The Integrated Plate Boundary Observatory Chile monitored the entire sequence of events, providing unprecedented resolution of the build-up to the main event and its rupture evolution. Here we show that the Iquique earthquake broke a central fraction of the so-called northern Chile seismic gap, the last major segment of the South American plate boundary that had not ruptured in the past century. Since July 2013 three seismic clusters, each lasting a few weeks, hit this part of the plate boundary with earthquakes of increasing peak magnitudes. Starting with the second cluster, geodetic observations show surface displacements that can be associated with slip on the plate interface. These seismic clusters and their slip transients occupied a part of the plate interface that was transitional between a fully locked and a creeping portion. Leading up to this earthquake, the b value of the foreshocks gradually decreased during the years before the earthquake, reversing its trend a few days before the Iquique earthquake. The mainshock finally nucleated at the northern end of the foreshock area, which skirted a locked patch, and ruptured mainly downdip towards higher locking. Peak slip was attained immediately downdip of the foreshock region and at the margin of the locked patch. We conclude that gradual weakening of the central part of the seismic gap accentuated by the foreshock activity in a zone of intermediate seismic coupling was instrumental in causing final failure, distinguishing the Iquique earthquake from most great earthquakes. Finally, only one-third of the gap was broken and the remaining locked segments now pose a significant, increased seismic hazard with the potential to host an earthquake with a magnitude of >8.5.

  6. Discrete quintic spline for boundary value problem in plate deflation theory

    Science.gov (United States)

    Wong, Patricia J. Y.

    2017-07-01

    We propose a numerical scheme for a fourth-order boundary value problem arising from plate deflation theory. The scheme involves a discrete quintic spline, and it is of order 4 if a parameter takes a specific value, else it is of order 2. We also present a well known numerical example to illustrate the efficiency of our method as well as to compare with other numerical methods proposed in the literature.

  7. Plane wave diffraction by a finite plate with impedance boundary conditions.

    Science.gov (United States)

    Nawaz, Rab; Ayub, Muhammad; Javaid, Akmal

    2014-01-01

    In this study we have examined a plane wave diffraction problem by a finite plate having different impedance boundaries. The Fourier transforms were used to reduce the governing problem into simultaneous Wiener-Hopf equations which are then solved using the standard Wiener-Hopf procedure. Afterwards the separated and interacted fields were developed asymptotically by using inverse Fourier transform and the modified stationary phase method. Detailed graphical analysis was also made for various physical parameters we were interested in.

  8. Plane wave diffraction by a finite plate with impedance boundary conditions.

    Directory of Open Access Journals (Sweden)

    Rab Nawaz

    Full Text Available In this study we have examined a plane wave diffraction problem by a finite plate having different impedance boundaries. The Fourier transforms were used to reduce the governing problem into simultaneous Wiener-Hopf equations which are then solved using the standard Wiener-Hopf procedure. Afterwards the separated and interacted fields were developed asymptotically by using inverse Fourier transform and the modified stationary phase method. Detailed graphical analysis was also made for various physical parameters we were interested in.

  9. Examples of the Re-number effect on the transitional flat plate boundary layers

    Czech Academy of Sciences Publication Activity Database

    Antoš, Pavel; Jonáš, Pavel; Procházka, Pavel P.; Uruba, Václav

    2014-01-01

    Roč. 14, č. 1 (2014), s. 605-606 ISSN 1617-7061. [Annual Meeting of the International Association of Applied Mathematics and Mechanics /85./. Erlangen, 10.03.2014-14.03.2014] R&D Projects: GA ČR GAP101/12/1271 Institutional support: RVO:61388998 Keywords : transition * flat plate * boundary layer Subject RIV: BK - Fluid Dynamics http://dx.doi.org/10.1002/pamm.201410290

  10. Four-parametric two-layer algebraic model of transition boundary layer at a planar plate

    International Nuclear Information System (INIS)

    Labusov, A.N.; Lapin, Yu.V.

    1996-01-01

    Consideration is given to four-parametric two-layer algebraic model of transition boundary layer on a plane plate, based on generalization of one-parametric algebraic Prandtl-Loitsjansky-Klauzer-3 model. The algebraic model uses Prandtl formulas for mixing path with Loitsjansky damping multiplier in the internal region and the relation for turbulent viscosity, based on universal scales of external region and named the Klauzer-3 formula. 12 refs., 10 figs

  11. Plate boundary reorganization in the active Banda Arc-continent collision: Insights from new GPS measurements

    Science.gov (United States)

    Nugroho, Hendro; Harris, Ron; Lestariya, Amin W.; Maruf, Bilal

    2009-12-01

    New GPS measurements reveal that large sections of the SE Asian Plate are progressively accreting to the edge of the Australian continent by distribution of strain away from the deformation front to forearc and backarc plate boundary segments. The study was designed to investigate relative motions across suspected plate boundary segments in the transition from subduction to collision. The oblique nature of the collision provides a way to quantify the spatial and temporal distribution of strain from the deformation front to the back arc. The 12 sites we measured from Bali to Timor included some from an earlier study and 7 additional stations, which extended the epoch of observation to ten years at many sites. The resulting GPS velocity field delineates at least three Sunda Arc-forearc regions around 500 km in strike-length that shows different amounts of coupling to the Australian Plate. Movement of these regions relative to SE Asia increases from 21% to 41% to 63% eastward toward the most advanced stages of collision. The regions are bounded by the deformation front to the south, the Flores-Wetar backarc thrust system to the north, and poorly defined structures on the sides. The suture zone between the NW Australian continental margin and the Sunda-Banda Arcs is still evolving with more than 20 mm/yr of movement measured across the Timor Trough deformation front between Timor and Australia.

  12. Effect of plate permeability on nonlinear stability of the asymptotic suction boundary layer.

    Science.gov (United States)

    Wedin, Håkan; Cherubini, Stefania; Bottaro, Alessandro

    2015-07-01

    The nonlinear stability of the asymptotic suction boundary layer is studied numerically, searching for finite-amplitude solutions that bifurcate from the laminar flow state. By changing the boundary conditions for disturbances at the plate from the classical no-slip condition to more physically sound ones, the stability characteristics of the flow may change radically, both for the linearized as well as the nonlinear problem. The wall boundary condition takes into account the permeability K̂ of the plate; for very low permeability, it is acceptable to impose the classical boundary condition (K̂=0). This leads to a Reynolds number of approximately Re(c)=54400 for the onset of linearly unstable waves, and close to Re(g)=3200 for the emergence of nonlinear solutions [F. A. Milinazzo and P. G. Saffman, J. Fluid Mech. 160, 281 (1985); J. H. M. Fransson, Ph.D. thesis, Royal Institute of Technology, KTH, Sweden, 2003]. However, for larger values of the plate's permeability, the lower limit for the existence of linear and nonlinear solutions shifts to significantly lower Reynolds numbers. For the largest permeability studied here, the limit values of the Reynolds numbers reduce down to Re(c)=796 and Re(g)=294. For all cases studied, the solutions bifurcate subcritically toward lower Re, and this leads to the conjecture that they may be involved in the very first stages of a transition scenario similar to the classical route of the Blasius boundary layer initiated by Tollmien-Schlichting (TS) waves. The stability of these nonlinear solutions is also investigated, showing a low-frequency main unstable mode whose growth rate decreases with increasing permeability and with the Reynolds number, following a power law Re(-ρ), where the value of ρ depends on the permeability coefficient K̂. The nonlinear dynamics of the flow in the vicinity of the computed finite-amplitude solutions is finally investigated by direct numerical simulations, providing a viable scenario for

  13. Transitional and turbulent flat-plate boundary layers with heat transfer

    Science.gov (United States)

    Wu, Xiaohua; Moin, Parviz

    2010-11-01

    We report on our direct numerical simulation of two incompressible, nominally zero-pressure-gradient flat-plate boundary layers from momentum thickness Reynolds number 80 to 1950. Heat transfer between the constant-temperature solid surface and the free-stream is also simulated with molecular Prandtl number=1. Throughout the entire flat-plate, the ratio of Stanton number and skin-friction St/Cfdeviates from the exact Reynolds analogy value of 0.5 by less than 1.5%. Turbulent Prandtl number t peaks at the wall. Preponderance of hairpin vortices is observed in both the transitional and turbulent regions of the boundary layers. In particular, the internal structure of merged turbulent spots is hairpin forest; the internal structure of infant turbulent spots is hairpin packet. Numerous hairpin vortices are readily detected in both the near-wall and outer regions of the boundary layers up to momentum thickness Reynolds number 1950. This suggests that the hairpin vortices in the turbulent region are not simply the aged hairpin forests convected from the upstream transitional region. Temperature iso-surfaces in the companion thermal boundary layers are found to be a useful tracer in identifying hairpin vortex structures.

  14. Streamwise counter-rotating vortices generated by triangular leading edge pattern in flat plate boundary layer

    KAUST Repository

    Hasheminejad, S. M.

    2016-01-05

    A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out for a Reynolds number based on the pattern wavelength (λ) of 3080. The results depict the onset, development and breakdown of the vortical structures within the flat plate boundary layer. Moreover, the effect of one spanwise array of holes with diameter of 0.2λ (=3 mm) was examined. This investigation was done on two different flat plates with holes placed at the location x/λ = 2 downstream of the troughs and peaks. The presence of holes after troughs does not show any significant effect on the vortical structures. However, the plate with holes after peaks noticeably delays the vortex breakdown. In this case, the “mushroom-like” vortices move away from the wall and propagate downstream with stable vortical structures. The vortex growth is halted further downstream but start to tilt aside.

  15. Asymmetric Vibration of Polar Orthotropic Annular Circular Plates of Quadratically Varying Thickness with Same Boundary Conditions

    Directory of Open Access Journals (Sweden)

    N. Bhardwaj

    2008-01-01

    Full Text Available In the present paper, asymmetric vibration of polar orthotropic annular circular plates of quadratically varying thickness resting on Winkler elastic foundation is studied by using boundary characteristic orthonormal polynomials in Rayleigh-Ritz method. Convergence of the results is tested and comparison is made with results already available in the existing literature. Numerical results for the first ten frequencies for various values of parameters describing width of annular plate, thickness profile, material orthotropy and foundation constant for all three possible combinations of clamped, simply supported and free edge conditions are shown and discussed. It is found that (a higher elastic property in circumferential direction leads to higher stiffness against lateral vibration; (b Lateral vibration characteristics of F-Fplates is more sensitive towards parametric changes in material orthotropy and foundation stiffness than C-C and S-Splates; (c Effect of quadratical thickness variation on fundamental frequency is more significant in cases of C-C and S-S plates than that of F-Fplates. Thickness profile which is convex relative to plate center-line tends to result in higher stiffness of annular plates against lateral vibration than the one which is concave and (d Fundamental mode of vibration of C-C and S-Splates is axisymmetrical while that of F-Fplates is asymmetrical.

  16. Plate boundary deformation at the latitude of the Salton Trough - northern Gulf of California (Invited)

    Science.gov (United States)

    Stock, J. M.

    2013-12-01

    Along the Pacific-North America plate boundary zone, the segment including the southern San Andreas fault to Salton Trough and northern Gulf of California basins has been transtensional throughout its evolution, based on Pacific-North America displacement vectors calculated from the global plate circuit (900 × 20 km at N54°W since 20 Ma; 460 × 20 km at N48°W since 11 Ma). Nevertheless, active seismicity and focal mechanisms show a broad zone of plate boundary deformation within which the inferred stress regime varies locally (Yang & Hauksson 2013 GJI), and fault patterns in some regions suggest ongoing tectonic rotation. Similar behavior is inferred to have occurred in this zone over most of its history. Crustal structure in this region is constrained by surface geology, geophysical experiments (e.g., the 2011 Salton Seismic Imaging Project (SSIP), USGS Imperial Valley 1979, PACE), and interdisciplinary marine and onland studies in Mexico (e.g., NARS-Baja, Cortes, and surveys by PEMEX). Magnetic data (e.g., EMAG-2) aids in the recognition of large-scale crustal provinces and fault boundaries in regions lacking detailed geophysical surveys. Consideration of existing constraints on crustal thickness and architecture, and fault and basin evolution suggests that to reconcile geological deformation with plate motion history, the following additional factors need to be taken into account. 1) Plate boundary displacement via interacting systems of rotating blocks, coeval with slip on steep strike slip faults, and possibly related to slip on low angle extensional faults (e.g, Axen & Fletcher 1998 IGR) may be typical prior to the onset of seafloor spreading. This fault style may have accommodated up to 150 km of plate motion in the Mexican Continental Borderland and north of the Vizcaino Peninsula, likely between 12 and 15 Ma, as well as explaining younger rotations adjacent to the Gulf of California and current deformation southwest of the Salton Sea. 2) Geophysical

  17. A Case Study of Offshore Advection of Boundary Layer Rolls over a Stably Stratified Sea Surface

    DEFF Research Database (Denmark)

    Svensson, Nina; Sahlée, Erik; Bergström, Hans

    2017-01-01

    originate from boundary layer rolls generated over the convective air above Swedish mainland, also supported by visual satellite images showing the typical signature cloud streets. The simulations indicate that the rolls are advected and maintained at least 30–80 km off the coast, in agreement...... considerably for long times and over large areas in coastal regions. Although boundary layer rolls are a well-studied feature, no previous study has presented results concerning their persistence during situations with advection to a strongly stratified boundary layer. Such conditions are commonly encountered...

  18. How diking affects the longer-term structure and evolution of divergent plate boundaries

    KAUST Repository

    Trippanera, Daniele

    2015-04-01

    Recurrent diking episodes along divergent plate boundaries, as at Dabbahu (2005, Afar) or at Bardarbunga (2014, Iceland) , highlight the possibility to have m-wide opening in a short time (days to weeks). This suggests a prominent role of magma enhancing transient plate separations. However, the role of diking on a longer term (> 102 years) and its influence on the structure and the evolution of a divergent plate boundary is still poorly investigated. Here we use field surveys along the oceanic Icelandic and continental Ethiopian plate boundaries, along five eruptive fissures and four rift segments. Field observations have also been integrated with analogue and numerical models of dike emplacement to better understand the effect of dike emplacement at depth and at the surface. Our results show that the dike-fed eruptive fissures are systematically associated with graben structures formed by inward dipping normal faults having throws up to 10 m and commonly propagating downward. Moreover, rift segments (i.e. mature rift zones), despite any asymmetry and repetition, are characterized by the same features as the eruptive fissures, the only difference lying in the larger size (higher fault throws, up to 40 m, and wider deformation zones). Analogue and numerical models of dike intrusion confirm that all the structural features observed along the rift segments may be dike-induced; these features include downward propagating normal faults bordering graben structures, contraction at the base of the hanging walls of the faults and upward propagating faults. Simple calculations based on the deeper structure of the eroded rift segments in eastern and western Iceland also suggest that all the fault slip in the active rift segments may result from diking. These results suggest that the overall deformation pattern of eruptive fissures and rift segments may be explained only by dike emplacement. In a magmatic rift, the regional tectonic stress may rarely be high enough to be

  19. Development of Streamwise Counter-Rotating Vortices in Flat Plate Boundary Layer Pre-set by Leading Edge Patterns

    KAUST Repository

    Hasheminejad, S.M.; Mitsudharmadi, Hatsari; Winoto, S.H.; Low, H.T.; Lua, K.B.

    2017-01-01

    Development of streamwise counter-rotating vortices induced by leading edge patterns with different pattern shape is investigated using hot-wire anemometry in the boundary layer of a flat plate. A triangular, sinusoidal and notched patterns

  20. Relaxation of an unsteady turbulent boundary layer on a flat plate in an expansion tube

    Science.gov (United States)

    Gurta, R. N.; Trimpi, R. L.

    1974-01-01

    An analysis is presented for the relaxation of a turbulent boundary layer on a semi-infinite flat plate after passage of a shock wave and a trailing driver gas-driven gas interface. The problem has special application to expansion-tube flows. The flow-governing equations have been transformed into the Crocco variables, and a time-similar solution is presented in terms of the dimensionless distance-time variable alpha and the dimensionless velocity variable beta. An eddy-viscosity model, similar to that of time-steady boundary layers, is applied to the inner and outer regions of the boundary layer. A turbulent Prandtl number equal to the molecular Prandtl number is used to relate the turbulent heat flux to the eddy viscosity. The numerical results, obtained by using the Gauss-Seidel line-relaxation method, indicate that a fully turbulent boundary layer relaxes faster to the final steady-state values of heat transfer and skin friction than a laminar boundary layer. The results also give a fairly good estimate of the local skin friction and heat transfer for near steady-flow conditions.

  1. Transition due to streamwise streaks in a supersonic flat plate boundary layer

    Science.gov (United States)

    Paredes, Pedro; Choudhari, Meelan M.; Li, Fei

    2016-12-01

    Transition induced by stationary streaks undergoing transient growth in a supersonic flat plate boundary layer flow is studied using numerical computations. While the possibility of strong transient growth of small-amplitude stationary perturbations in supersonic boundary layer flows has been demonstrated in previous works, its relation to laminar-turbulent transition cannot be established within the framework of linear disturbances. Therefore, this paper investigates the nonlinear evolution of initially linear optimal disturbances that evolve into finite amplitude streaks in the downstream region, and then studies the modal instability of those streaks as a likely cause for the onset of bypass transition. The nonmodal evolution of linearly optimal stationary perturbations in a supersonic, Mach 3 flat plate boundary layer is computed via the nonlinear plane-marching parabolized stability equations (PSE) for stationary perturbations, or equivalently, the perturbation form of parabolized Navier-Stokes equations. To assess the effect of the nonlinear finite-amplitude streaks on transition, the linear form of plane-marching PSE is used to investigate the instability of the boundary layer flow modified by the spanwise periodic streaks. The onset of transition is estimated using an N -factor criterion based on modal amplification of the secondary instabilities of the streaks. In the absence of transient growth disturbances, first mode instabilities in a Mach 3, zero pressure gradient boundary layer reach N =10 at Rex≈107 . However, secondary instability modes of the stationary streaks undergoing transient growth are able to achieve the same N -factor at Rex<2 ×106 when the initial streak amplitude is sufficiently large. In contrast to the streak instabilities in incompressible flows, subharmonic instability modes with twice the fundamental spanwise wavelength of the streaks are found to have higher amplification ratios than the streak instabilities at fundamental

  2. Geometry and structure of the pull-apart basins developed along the western South American-Scotia plate boundary (SW Atlantic Ocean)

    Science.gov (United States)

    Esteban, F. D.; Tassone, A.; Isola, J. I.; Lodolo, E.; Menichetti, M.

    2018-04-01

    The South American-Scotia plate boundary is a left-lateral fault system which runs roughly E-W for more than 3000 km across the SW Atlantic Ocean and the Tierra del Fuego Island, reaching to the west the southern Chile Trench. Analyses of a large dataset of single- and multi-channel seismic reflection profiles acquired offshore has allowed to map the trace of the plate boundary from Tierra del Fuego to the Malvinas Trough, a tectonic depression located in the eastern part of the fault system, and to reconstruct the shape and geometry of the basins formed along the principal displacement zone of the fault system. Three main Neogene pull-apart basins that range from 70 to 100 km in length, and from 12 to 22 km in width, have been identified along this segment of the plate boundary. These basins have elongated shapes with their major axes parallel to the ENE-WSW direction of the fault zone. The sedimentary architecture and the infill geometry of the basins suggest that they represent mostly strike-slip dominated transtension basins which propagated from E to W. The basins imaged by seismic data show in some cases geometrical and structural features linked to the possible reactivation of previous wedge-top basins and inherited structures pertaining to the external front of the Magallanes fold-and-thrust compression belt, along which the South American-Scotia fault system has been superimposed. It is suggested that the sequence of the elongated basins occur symmetrically to a thorough going strike-slip fault, in a left-stepping geometrical arrangement, in a manner similar to those basins seen in other transcurrent environments.

  3. Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland

    KAUST Repository

    Keiding, Marie

    2010-07-01

    We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.

  4. Plate boundary deformation and man-made subsidence around geothermal fields on the Reykjanes Peninsula, Iceland

    KAUST Repository

    Keiding, Marie; Á rnadó ttir, Thó ra; Jonsson, Sigurjon; Decriem, Judicaë l; Hooper, Andrew John

    2010-01-01

    We present Interferometric Synthetic Aperture Radar (InSAR) data from 1992-1999 and 2003-2008 as well as GPS data from 2000-2009 for the active plate boundary on the Reykjanes Peninsula, southwest Iceland. The geodetic data reveal deformation mainly due to plate spreading, anthropogenic subsidence caused by geothermal fluid extraction and, possibly, increasing pressure in a geothermal system. Subsidence of around 10. cm is observed during the first 2. years of production at the Reykjanes geothermal power plant, which started operating in May 2006. We model the surface subsidence around the new power plant using point and ellipsoidal pressure sources in an elastic halfspace. Short-lived swarms of micro-earthquakes as well as aseismic fault movement are observed near the geothermal field following the start of production, possibly triggered by the stresses induced by geothermal fluid extraction. © 2010 Elsevier B.V.

  5. Architectural Blueprint for Plate Boundary Observatories based on interoperable Data Management Platforms

    Science.gov (United States)

    Kerschke, D. I.; Häner, R.; Schurr, B.; Oncken, O.; Wächter, J.

    2014-12-01

    Interoperable data management platforms play an increasing role in the advancement of knowledge and technology in many scientific disciplines. Through high quality services they support the establishment of efficient and innovative research environments. Well-designed research environments can facilitate the sustainable utilization, exchange, and re-use of scientific data and functionality by using standardized community models. Together with innovative 3D/4D visualization, these concepts provide added value in improving scientific knowledge-gain, even across the boundaries of disciplines. A project benefiting from the added value is the Integrated Plate boundary Observatory in Chile (IPOC). IPOC is a European-South American network to study earthquakes and deformation at the Chilean continental margin and to monitor the plate boundary system for capturing an anticipated great earthquake in a seismic gap. In contrast to conventional observatories that monitor individual signals only, IPOC captures a large range of different processes through various observation methods (e.g., seismographs, GPS, magneto-telluric sensors, creep-meter, accelerometer, InSAR). For IPOC a conceptual design has been devised that comprises an architectural blueprint for a data management platform based on common and standardized data models, protocols, and encodings as well as on an exclusive use of Free and Open Source Software (FOSS) including visualization components. Following the principles of event-driven service-oriented architectures, the design enables novel processes by sharing and re-using functionality and information on the basis of innovative data mining and data fusion technologies. This platform can help to improve the understanding of the physical processes underlying plate deformations as well as the natural hazards induced by them. Through the use of standards, this blueprint can not only be facilitated for other plate observing systems (e.g., the European Plate

  6. Boundary Layer Flow and Heat Transfer of FMWCNT/Water Nanofluids over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Safaei

    2016-09-01

    Full Text Available In the present study, the heat transfer and flow of water/FMWCNT (functionalized multi-walled carbon nanotube nanofluids over a flat plate was investigated using a finite volume method. Simulations were performed for velocity ranging from 0.17 mm/s to 1.7 mm/s under laminar regime and nanotube concentrations up to 0.2%. The 2-D governing equations were solved using an in-house FORTRAN code. For a specific free stream velocity, the presented results showed that increasing the weight percentage of nanotubes increased the Nusselt number. However, an increase in the solid weight percentage had a negligible effect on the wall shear stress. The results also indicated that increasing the free stream velocity for all cases leads to thinner boundary layer thickness, while increasing the FMWCNT concentration causes an increase in the boundary layer thickness.

  7. Direct simulation of flat-plate boundary layer with mild free-stream turbulence

    Science.gov (United States)

    Wu, Xiaohua; Moin, Parviz

    2014-11-01

    Spatially evolving direct numerical simulation of the flat-plate boundary layer has been performed. The momentum thickness Reynolds number develops from 80 to 3000 with a free-stream turbulence intensity decaying from 3 percent to 0.8 percent. Predicted skin-friction is in agreement with the Blasius solution prior to breakdown, follows the well-known T3A bypass transition data during transition, and agrees with the Erm and Joubert Melbourne wind-tunnel data after the completion of transition. We introduce the concept of bypass transition in the narrow sense. Streaks, although present, do not appear to be dynamically important during the present bypass transition as they occur downstream of infant turbulent spots. For the turbulent boundary layer, viscous scaling collapses the rate of dissipation profiles in the logarithmic region at different Reynolds numbers. The ratio of Taylor microscale and the Kolmogorov length scale is nearly constant over a large portion of the outer layer. The ratio of large-eddy characteristic length and the boundary layer thickness scales very well with Reynolds number. The turbulent boundary layer is also statistically analyzed using frequency spectra, conditional-sampling, and two-point correlations. Near momentum thickness Reynolds number of 2900, three layers of coherent vortices are observed: the upper and lower layers are distinct hairpin forests of large and small sizes respectively; the middle layer consists of mostly fragmented hairpin elements.

  8. Skin friction drag reduction on a flat plate turbulent boundary layer using synthetic jets

    Science.gov (United States)

    Belanger, Randy; Boom, Pieter D.; Hanson, Ronald E.; Lavoie, Philippe; Zingg, David W.

    2017-11-01

    In these studies, we investigate the effect of mild synthetic jet actuation on a flat plate turbulent boundary layer with the goal of interacting with the large scales in the log region of the boundary layer and manipulating the overall skin friction. Results will be presented from both large eddy simulations (LES) and wind tunnel experiments. In the experiments, a large parameter space of synthetic jet frequency and amplitude was studied with hot film sensors at select locations behind a pair of synthetic jets to identify the parameters that produce the greatest changes in the skin friction. The LES simulations were performed for a selected set of parameters and provide a more complete evaluation of the interaction between the boundary layer and synthetic jets. Five boundary layer thicknesses downstream, the skin friction between the actuators is generally found to increase, while regions of reduced skin friction persist downstream of the actuators. This pattern is reversed for forcing at low frequency. Overall, the spanwise-averaged skin friction is increased by the forcing, except when forcing at high frequency and low amplitude, for which a net skin friction reduction persists downstream. The physical interpretation of these results will be discussed. The financial support of Airbus is gratefully acknowledged.

  9. An analytical study of the free and forced vibration response of a ribbed plate with free boundary conditions

    Science.gov (United States)

    Lin, Tian Ran; Zhang, Kai

    2018-05-01

    An analytical study to predict the vibration response of a ribbed plate with free boundary conditions is presented. The analytical solution was derived using a double cosine integral transform technique and then utilized to study the free and forced vibration of the ribbed plate, as well as the effect of the rib on the modal response of the uniform plate. It is shown that in addition to the three zero-frequency rigid body modes of the plate, the vibration modes of the uniform plate can be classified into four mode groups according to the symmetric properties of the plate with respect to the two orthogonal middle lines parallel to the plate edges. The four mode groups correspond to a double symmetric group, a double anti-symmetric group and two symmetric/anti-symmetric groups. Whilst the inclusion of the rib to the plate is shown to cause distortion to the distribution of vibration modes, most modes can still be traced back to the original modes of the uniform plate. Both the mass and stiffness of the rib are shown to affect the modal vibration of the uniform plate, whereby a dominant effect from the rib mass leads to a decrease in the modal frequency of the plate, whereas a dominant effect from the rib stiffness leads to an increase in plate modal frequency. When the stiffened rib behaves as an effective boundary to the plate vibration, an original plate mode becomes a pair of degenerate modes, whereby one mode has a higher frequency and the other mode has a lower frequency than that of the original mode.

  10. Fluid flow and heat transfer of carbon nanotubes along a flat plate with Navier slip boundary

    Science.gov (United States)

    Khan, W. A.; Khan, Z. H.; Rahi, M.

    2014-06-01

    Homogeneous flow model is used to study the flow and heat transfer of carbon nanotubes (CNTs) along a flat plate subjected to Navier slip and uniform heat flux boundary conditions. This is the first paper on the flow and heat transfer of CNTs along a flat plate. Two types of CNTs, namely, single- and multi-wall CNTs are used with water, kerosene or engine oil as base fluids. The empirical correlations are used for the thermophysical properties of CNTs in terms of the solid volume fraction of CNTs. For the effective thermal conductivity of CNTs, Xue (Phys B Condens Matter 368:302-307, 2005) model has been used and the results are compared with the existing theoretical models. The governing partial differential equations and boundary conditions are converted into a set of nonlinear ordinary differential equations using suitable similarity transformations. These equations are solved numerically using a very efficient finite difference method with shooting scheme. The effects of the governing parameters on the dimensionless velocity, temperature, skin friction, and Nusselt numbers are investigated and presented in graphical and tabular forms. The numerical results of skin friction and Nusselt numbers are compared with the available data for special cases and are found in good agreement.

  11. The ultra low frequency electromagnetic radiation observed in the topside ionosphere above boundaries of tectonic plates

    Directory of Open Access Journals (Sweden)

    Michael A. Athanasiou

    2015-01-01

    Full Text Available In this paper we present results of a comparison between ultra low frequency (ULF electromagnetic (EM radiation, recorded by an electric field instrument onboard the satellite detection of electromagnetic emissions transmitted from earthquake regions in the topside ionosphere, and the seismicity of regions with high and low seismic activity. In particular, we evaluated the energy variations of the ULF Ezelectric field component during a period of four years (2006-2009, in order to examine the possible relation of ULF EM radiation with seismogenic regions located in Central America, Indonesia, the Eastern Mediterranean Basin and Greece. As a tool for evaluating the ULF Ez energy variations we used singular spectrum analysis techniques. The results of our analysis clearly show a significant increase of the ULF EM energy emitted from regions of highest seismic activity at the boundaries tectonic plates. Furthermore, we found that higher electromagnetic radiation was detected in a region above the northern- western Greek Arc (R1 than above the adjacent region including Athens and its urban area. We interpret these results of the present study as suggesting that: i the seismogenic regions at the boundary of tectonic plates radiate ULF EM emissions observed by satellites in the topside ionosphere; and ii that this EM radiation is not only related with the occurrence time of great (M≥5 earthquakes, but it is often present in intermediate times and it appears as a quasi-permanent phenomenon.

  12. Numerical investigation of a spatially developing turbulent natural convection boundary layer along a vertical heated plate

    International Nuclear Information System (INIS)

    Nakao, Keisuke; Hattori, Yasuo; Suto, Hitoshi

    2017-01-01

    Highlights: • A large-eddy simulation of a spatially developing natural convection boundary layer is conducted. • First- and second-order moments of the heat and momentum showed a reasonable agreement with past experiments. • Coherent structure of turbulent vortex inherent in this boundary layer is discussed. - Abstract: Large-eddy simulation (LES) on a spatially developing natural convection boundary layer along a vertical heated plate was conducted. The heat transfer rate, friction velocity, mean velocity and temperature, and second-order turbulent properties both in the wall-normal and the stream-wise direction showed reasonable agreement with the findings of past experiments. The spectrum of velocity and temperature fluctuation showed a -2/3-power decay slope and -2-power decay slope respectively. Quadrant analysis revealed the inclination on Q1 and Q3 in the Reynolds stress and turbulent heat flux, changing their contribution along the distance from the plate surface. Following the convention, we defined the threshold region where the stream-wise mean velocity takes local maximum, the inner layer which is closer to the plate than the threshold region, the outer layer which is farther to the plate than the threshold region. The space correlation of stream-wise velocity tilted the head toward the wall in the propagating direction in the outer layer; on the other hand, the correlated motion had little inclination in the threshold region. The time history of the second invariant of gradient tensor Q revealed that the vortex strength oscillates both in the inner and the outer layers in between the laminar and the transition region. In the turbulent region, the vortex was often dominant in the outer layer. Instantaneous three-dimensional visualization of Q revealed the existence of high-speed fluid parcels associated with arch-shape vortices. These results were considered as an intrinsic structure in the outer layer, which is symmetrical to the structure of

  13. The structure of the stably stratified internal boundary layer in offshore flow over the sea

    Science.gov (United States)

    Garratt, J. R.; Ryan, B. F.

    1989-04-01

    Observations obtained mainly from a research aircraft are presented of the mean and turbulent structure of the stably stratified internal boundary layer (IBL) over the sea formed by warm air advection from land to sea. The potential temperature and humidity fields reveal the vertical extent of the IBL, for fetches out to several hundred of kilometres, geostrophic winds of 20 25 m s-1, and potential temperature differences between undisturbed continental air and the sea surface of 7 to 17 K. The dependence of IBL depth on these external parameters is discussed in the context of the numerical results of Garratt (1987), and some discrepancies are noted. Wind observations show the development of a low-level wind maximum (wind component normal to the coast) and rotation of the wind to smaller cross-isobar flow angles. Potential temperature (θ) profiles within the IBL reveal quite a different structure to that found in the nocturnal boundary layer (NBL) over land. Over the sea, θ profiles have large positive curvature with vertical gradients increasing monotonically with height; this reflects the dominance of turbulent cooling within the layer. The behaviour is consistent with known behaviour in the NBL over land where curvature becomes negative (vertical gradients of θ decreasing with height) as radiative cooling becomes dominant. Turbulent properties are discussed in terms of non-dimensional quantities, normalised by the surface friction velocity, as functions of normalised height using the IBL depth. Vertical profiles of these and the normalised wavelength of the spectral maximum agree well with known results for the stable boundary layer over land (Caughey et al., 1979).

  14. Numerical investigation of hypersonic flat-plate boundary layer transition mechanism induced by different roughness shapes

    Science.gov (United States)

    Zhou, Yunlong; Zhao, Yunfei; Xu, Dan; Chai, Zhenxia; Liu, Wei

    2016-10-01

    The roughness-induced laminar-turbulent boundary layer transition is significant for high-speed aerospace applications. The transition mechanism is closely related to the roughness shape. In this paper, high-order numerical method is used to investigate the effect of roughness shape on the flat-plate laminar-to-turbulent boundary layer transition. Computations are performed in both the supersonic and hypersonic regimes (free-stream Mach number from 3.37 up to 6.63) for the square, cylinder, diamond and hemisphere roughness elements. It is observed that the square and diamond roughness elements are more effective in inducing transition compared with the cylinder and hemisphere ones. The square roughness element has the longest separated region in which strong unsteadiness exists and the absolute instability is formed, thus resulting in the earliest transition. The diamond roughness element has a maximum width of the separated region leading to the widest turbulent wake region far downstream. Furthermore, transition location moves backward as the Mach number increases, which indicates that the compressibility significantly suppresses the roughness-induced boundary layer transition.

  15. Boundary integral equation methods and numerical solutions thin plates on an elastic foundation

    CERN Document Server

    Constanda, Christian; Hamill, William

    2016-01-01

    This book presents and explains a general, efficient, and elegant method for solving the Dirichlet, Neumann, and Robin boundary value problems for the extensional deformation of a thin plate on an elastic foundation. The solutions of these problems are obtained both analytically—by means of direct and indirect boundary integral equation methods (BIEMs)—and numerically, through the application of a boundary element technique. The text discusses the methodology for constructing a BIEM, deriving all the attending mathematical properties with full rigor. The model investigated in the book can serve as a template for the study of any linear elliptic two-dimensional problem with constant coefficients. The representation of the solution in terms of single-layer and double-layer potentials is pivotal in the development of a BIEM, which, in turn, forms the basis for the second part of the book, where approximate solutions are computed with a high degree of accuracy. The book is intended for graduate students and r...

  16. Human reliability analysis—Taxonomy and praxes of human entropy boundary conditions for marine and offshore applications

    International Nuclear Information System (INIS)

    El-Ladan, S.B.; Turan, O.

    2012-01-01

    This is the first stage towards the development of a human reliability model called human entropy (HENT). The paper presents qualitative and quantitative taxonomies and praxes of performance shaping factors (PSF) for Marine and Offshore operations. Three structured and guided expert elicitation methods were used in this study. The experts interrogated accident reports and databases from which the generic root causes of failures/accidents in operations are determined. The elicitations led to the development of 9 qualitative and quantitative human influencing factors, which are called Human Entropy Boundary Conditions (HEBC). Further explications of the 9 HEBC gave birth to 137 quantifiable explanatory variables, which are called hypothetical constructs (HyC). The HyCs are used to identify potential risks due to shrinkages in safety standards. Human entropy is a detour from traditional human error and was used as a result of tripartite human failure modes; error, local rationality and extraneous acts, all of which signify disorderliness and are seemingly inevitable in maritime operations. The praxes and scaling of HEBC was developed as guidance towards a practical oriented HRA and provide inputs for measuring human disorderliness in maritime operations.

  17. Seismicity and Seismic Hazard along the Western part of the Eurasia-Nubia plate boundary

    Science.gov (United States)

    Bezzeghoud, Mourad; Fontiela, João; Ferrão, Celia; Borges, José Fernando; Caldeira, Bento; Dib, Assia; Ousadou, Farida

    2016-04-01

    The seismic phenomenon is the most damaging natural hazard known in the Mediterranean area. The western part of the Eurasia-Nubia plate boundary extends from the Azores to the Mediterranean region. The oceanic part of the plate boundary is well delimited from the Azores Islands, along the Azores-Gibraltar fault to approximately 12°W (west of the Strait of Gibraltar). From 12°W to 3.5°E, including the Iberia-Nubia region and extending to the western part of Algeria, the boundary is more diffuse and forms a wider area of deformation. The boundary between the Iberia and Nubia plates is the most complex part of the margin. This region corresponds to the transition from an oceanic boundary to a continental boundary, where Iberia and Nubia collide. Although most earthquakes along this plate boundary are shallow and generally have magnitudes less than 5.5, there have been several high-magnitude events. Many devastating earthquakes, some of them tsunami-triggering, inflicted heavy loss and considerable economic damage to the region. From 1920 to present, three earthquakes with magnitudes of about 8.0 (Mw 8.2, 25 November 1941; Ms 8.0, 25 February 1969; and Mw 7.9, 26 May 1975) occurred in the oceanic region, and four earthquakes with magnitudes of about 7.0 (Mw 7.1, 8 May 1939, Santa Maria Island and Mw 7.1, January 1980, Terceira and Graciosa Islands, both in the Azores; Ms 7.1, 20 May 1931, Azores-Gibraltar fracture zone; and Mw 7.3, 10 October 1980, El Asnam, Algeria) occurred along the western part of the Eurasia-Nubia plate boundary. In general, large earthquakes (M ≥7) occur within the oceanic region, with the exception of the El Asnam (Algeria) earthquakes. Some of these events caused extensive damage. The 1755 Lisbon earthquake (˜Mw 9) on the Portugal Atlantic margin, about 200 km W-SW of Cape St. Vincent, was followed by a tsunami and fires that caused the near-total destruction of Lisbon and adjacent areas. Estimates of the death toll in Lisbon alone (~70

  18. Free Vibration Study of Anti-Symmetric Angle-Ply Laminated Plates under Clamped Boundary Conditions

    Science.gov (United States)

    Viswanathan, K. K.; Karthik, K.; Sanyasiraju, Y. V. S. S.; Aziz, Z. A.

    2016-11-01

    Two type of numerical approach namely, Radial Basis Function and Spline approximation, used to analyse the free vibration of anti-symmetric angle-ply laminated plates under clamped boundary conditions. The equations of motion are derived using YNS theory under first order shear deformation. By assuming the solution in separable form, coupled differential equations obtained in term of mid-plane displacement and rotational functions. The coupled differential is then approximated using Spline function and radial basis function to obtain the generalize eigenvalue problem and parametric studies are made to investigate the effect of aspect ratio, length-to-thickness ratio, number of layers, fibre orientation and material properties with respect to the frequency parameter. Some results are compared with the existing literature and other new results are given in tables and graphs.

  19. Interaction between central volcanoes and regional tectonics along divergent plate boundaries: Askja, Iceland

    Science.gov (United States)

    Trippanera, Daniele; Ruch, Joël; Acocella, Valerio; Thordarson, Thor; Urbani, Stefano

    2018-01-01

    Activity within magmatic divergent plate boundaries (MDPB) focuses along both regional fissure swarms and central volcanoes. An ideal place to investigate their mutual relationship is the Askja central volcano in Iceland. Askja consists of three nested calderas (namely Kollur, Askja and Öskjuvatn) located within a hyaloclastite massif along the NNE-SSW trending Icelandic MDPB. We performed an extensive field-based structural analysis supported by a remote sensing study of tectonic and volcanic features of Askja's calderas and of the eastern flank of the hyaloclastite massif. In the massif, volcano-tectonic structures trend N 10° E to N 40° E, but they vary around the Askja caldera being both parallel to the caldera rim and cross-cutting on the Western side. Structural trends around the Öskjuvatn caldera are typically rim parallel. Volcanic vents and dikes are preferentially distributed along the caldera ring faults; however, they follow the NNE-SSW regional structures when located outside the calderas. Our results highlight that the Askja volcano displays a balanced amount of regional (fissure-swarm related) and local (shallow-magma-chamber related) tectonic structures along with a mutual interaction among these. This is different from Krafla volcano (to the north of Askja) dominated by regional structures and Grímsvötn (to the South) dominated by local structures. Therefore, Askja represents an intermediate tectono-magmatic setting for volcanoes located in a slow divergent plate boundary. This is also likely in accordance with a northward increase in the spreading rate along the Icelandic MDPB.

  20. Interaction between central volcanoes and regional tectonics along divergent plate boundaries: Askja, Iceland

    KAUST Repository

    Trippanera, Daniele

    2017-12-04

    Activity within magmatic divergent plate boundaries (MDPB) focuses along both regional fissure swarms and central volcanoes. An ideal place to investigate their mutual relationship is the Askja central volcano in Iceland. Askja consists of three nested calderas (namely Kollur, Askja and Öskjuvatn) located within a hyaloclastite massif along the NNE-SSW trending Icelandic MDPB. We performed an extensive field-based structural analysis supported by a remote sensing study of tectonic and volcanic features of Askja’s calderas and of the eastern flank of the hyaloclastite massif. In the massif, volcano-tectonic structures trend N 10° E to N 40° E, but they vary around the Askja caldera being both parallel to the caldera rim and cross-cutting on the Western side. Structural trends around the Öskjuvatn caldera are typically rim parallel. Volcanic vents and dikes are preferentially distributed along the caldera ring faults; however, they follow the NNE-SSW regional structures when located outside the calderas. Our results highlight that the Askja volcano displays a balanced amount of regional (fissure-swarm related) and local (shallow-magma-chamber related) tectonic structures along with a mutual interaction among these. This is different from Krafla volcano (to the north of Askja) dominated by regional structures and Grímsvötn (to the South) dominated by local structures. Therefore, Askja represents an intermediate tectono-magmatic setting for volcanoes located in a slow divergent plate boundary. This is also likely in accordance with a northward increase in the spreading rate along the Icelandic MDPB.

  1. Development of the Plate Boundary Observatory GPS Low Latency Salton Trough Radio Network

    Science.gov (United States)

    Walls, C.; Miller, S.; Wilson, B.; Lawrence, S.; Arnitz, E.

    2008-05-01

    UNAVCO is developing a 20 GPS station low latency radio network that spans the San Andreas and San Jacinto faults in the region of highest strain in southern California and the narrowest part of the North America-Pacific plate boundary. The Salton Trough Radio Network (STRN) is instrumented with Ethernet bridge Intuicom EB6+ (900 MHz) radios to transmit a high rate low latency data stream from each permanent GPS site for the purpose of the following: 1) telemeter 15 second data (1 MB/day/station) to the Plate Boundary Observatory archive, 2) accommodate the timely download of 1 and 5 sample per second data following large earthquakes (4 MB/hour/station), and 3) test the UStream of 1Hz BINEX and RTCM data. Three of four phases have been completed. Office radio testing yielded transfer rates of 30-50 KB/s with subsecond latency while streaming 1 Hz data. Latency climbed to ~1.8 seconds while simultaneously streaming 1 Hz and downloading hourly 1 and 5 sample per second data files. Field testing demonstrated rates on the order of 30 KB/s. At present the radios are installed and have transfer rates of 10-40 KB/s between sites that span 10-32 km. The final phase will be the installation of the main telemetry relay where master radios will be connected to a high speed ISP near the town of Brawley. The high-rate low latency UStream data will be available to researchers who are developing prototype earthquake early warning systems in Southern California. A goal of the STRN is to make the data available rapidly enough for GPS-derived coseismic and dynamic displacements to be integrated into early warning system earthquake models. The improved earthquake models will better assist emergency response. UStream data will also aid surveyors who wish to use PBO GPS stations as permanent, high-quality base stations in real-time kinematic surveys.

  2. Logistical Support for the Installation of the Plate Boundary Observatory GPS and Borehole Strainmeter Networks

    Science.gov (United States)

    Kurnik, C.; Austin, K.; Coyle, B.; Dittmann, T.; Feaux, K.; Friesen, B.; Johnson, W.; Mencin, D.; Pauk, B.; Walls, C.

    2007-12-01

    The Plate Boundary Observatory (PBO), part of the NSF-funded EarthScope project, is designed to study the three- dimensional strain field resulting from deformation across the active boundary zone between the Pacific and North American plates in the western United States. To meet these goals, UNAVCO will install 880 continuous GPS stations, 103 borehole strainmeter stations, 28 tiltmeters, and five laser strainmeters by October 2008. Such a broad network presents significant logisitical challenges, including moving supplies, equipment, and personnel around 6 million square kilometers, and this requires accurate tracking and careful planning. The PBO logistics chain includes the PBO headquarters at UNAVCO in Boulder, Colorado and five regional offices in the continental United States and Alaska, served by dozens of suppliers spread across the globe. These offices are responsible for building and maintaining sites in their region. Most equipment and supplies first arrive in Boulder, where they are tagged and entered into a UNAVCO-wide equipment database, assembled and quality checked as necessary, and sent on to the appropriate regional office. Larger items which are costly to store and ship from Boulder, such as batteries or long sections of stainless steel pipe and bar required for monuments, are shipped directly from the supplier to each region as needed. These supplies and equipment are also tracked through the ordering, delivery, installation, and maintenance cycle via Earned Value Management techniques which allow us to meet NSF and other Federal procurement rules. Early prototypes and assembly configurations aid the development of material and supply budgets. A thorough understanding of Federal procurement rules at project start up is critical as the project moves forward.

  3. Effect of inherited structures on strike-slip plate boundaries: insight from analogue modelling of the central Levant Fracture System, Lebanon

    Science.gov (United States)

    Ghalayini, Ramadan; Daniel, Jean-Marc; Homberg, Catherine; Nader, Fadi

    2015-04-01

    Analogue sandbox modeling is a tool to simulate deformation style and structural evolution of sedimentary basins. The initial goal is to test what is the effect of inherited and crustal structures on the propagation, evolution, and final geometry of major strike-slip faults at the boundary between two tectonic plates. For this purpose, we have undertaken a series of analogue models to validate and reproduce the structures of the Levant Fracture System, a major NNE-SSW sinistral strike-slip fault forming the boundary between the Arabian and African plates. Onshore observations and recent high quality 3D seismic data in the Levant Basin offshore Lebanon demonstrated that Mesozoic ENE striking normal faults were reactivated into dextral strike-slip faults during the Late Miocene till present day activity of the plate boundary which shows a major restraining bend in Lebanon with a ~ 30°clockwise rotation in its trend. Experimental parameters consisted of a silicone layer at the base simulating the ductile crust, overlain by intercalated quartz sand and glass sand layers. Pre-existing structures were simulated by creating a graben in the silicone below the sand at an oblique (>60°) angle to the main throughgoing strike-slip fault. The latter contains a small stepover at depth to create transpression during sinistral strike-slip movement and consequently result in mountain building similarly to modern day Lebanon. Strike-slip movement and compression were regulated by steady-speed computer-controlled engines and the model was scanned using a CT-scanner continuously while deforming to have a final 4D model of the system. Results showed that existing normal faults were reactivated into dextral strike-slip faults as the sinistral movement between the two plates accumulated. Notably, the resulting restraining bend is asymmetric and segmented into two different compartments with differing geometries. One compartment shows a box fold anticline, while the second shows an

  4. Does permanent extensional deformation in lower forearc slopes indicate shallow plate-boundary rupture?

    Science.gov (United States)

    Geersen, J.; Ranero, C. R.; Kopp, H.; Behrmann, J. H.; Lange, D.; Klaucke, I.; Barrientos, S.; Diaz-Naveas, J.; Barckhausen, U.; Reichert, C.

    2018-05-01

    Seismic rupture of the shallow plate-boundary can result in large tsunamis with tragic socio-economic consequences, as exemplified by the 2011 Tohoku-Oki earthquake. To better understand the processes involved in shallow earthquake rupture in seismic gaps (where megathrust earthquakes are expected), and investigate the tsunami hazard, it is important to assess whether the region experienced shallow earthquake rupture in the past. However, there are currently no established methods to elucidate whether a margin segment has repeatedly experienced shallow earthquake rupture, with the exception of mechanical studies on subducted fault-rocks. Here we combine new swath bathymetric data, unpublished seismic reflection images, and inter-seismic seismicity to evaluate if the pattern of permanent deformation in the marine forearc of the Northern Chile seismic gap allows inferences on past earthquake behavior. While the tectonic configuration of the middle and upper slope remains similar over hundreds of kilometers along the North Chilean margin, we document permanent extensional deformation of the lower slope localized to the region 20.8°S-22°S. Critical taper analyses, the comparison of permanent deformation to inter-seismic seismicity and plate-coupling models, as well as recent observations from other subduction-zones, including the area that ruptured during the 2011 Tohoku-Oki earthquake, suggest that the normal faults at the lower slope may have resulted from shallow, possibly near-trench breaking earthquake ruptures in the past. In the adjacent margin segments, the 1995 Antofagasta, 2007 Tocopilla, and 2014 Iquique earthquakes were limited to the middle and upper-slope and the terrestrial forearc, and so are upper-plate normal faults. Our findings suggest a seismo-tectonic segmentation of the North Chilean margin that seems to be stable over multiple earthquake cycles. If our interpretations are correct, they indicate a high tsunami hazard posed by the yet un

  5. Boundary Layer of Photon Absorption Applied to Heterogeneous Photocatalytic Solar Flat Plate Reactor Design

    Directory of Open Access Journals (Sweden)

    Héctor L. Otálvaro-Marín

    2014-01-01

    Full Text Available This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA were used as design parameters to determine (i reactor thickness, (ii maximum absorbed radiant energy, and (iii the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA inside the reactor was described using six-flux absorption-scattering model (SFM applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.

  6. Frictional power dissipation on plate boundary faults: Implications for coseismic slip propagation at near-surface depths

    Science.gov (United States)

    Ikari, M.; Kopf, A.; Saffer, D. M.; Marone, C.; Carpenter, B. M.

    2013-12-01

    The general lack of earthquake slip at shallow (behavior associated with laboratory observations that disaggregated fault gouges commonly strengthen with increasing sliding velocity (i.e. velocity-strengthening friction), which precludes strain energy release via stress drops. However, the 2011 Tohoku earthquake demonstrated that coseismic rupture and slip can sometimes propagate to the surface in subduction zones. Surface rupture is also known to occur on other plate boundary faults, such as the Alpine Fault in New Zealand. It is uncertain how the extent of coseismic slip propagation from depth is controlled by the frictional properties of the near-surface portion of major faults. In these situations, it is common for slip to localize within gouge having a significant component of clay minerals, which laboratory experiments have shown are generally weak and velocity strengthening. However, low overall fault strength should facilitate coseismic slip, while velocity-strengthening behavior would resist it. In order to investigate how frictional properties may control the extent of coseismic slip propagation at shallow depths, we compare frictional strength and velocity-dependence measurements using samples from three subduction zones known for hosting large magnitude earthquakes. We focus on samples recovered during scientific drilling projects from the Nankai Trough, Japan, the Japan Trench in the region of the Tohoku earthquake, and the Middle America Trench, offshore Costa Rica; however we also include comparisons with other major fault zones sampled by drilling. In order to incorporate the combined effects of overall frictional strength and friction velocity-dependence, we estimate shear strength as a function of slip velocity (at constant effective normal stress), and integrate this function to obtain the areal power density, or frictional power dissipation capability of the fault zone. We also explore the role of absolute shear stress level before arrival of a

  7. An eddy-viscosity treatment of the unsteady turbulent boundary layer on a flat plate in an expansion tube

    Science.gov (United States)

    Gupta, R. N.; Trimpi, R. L.

    1974-01-01

    An analysis is presented for the relaxation of a turbulent boundary layer on a semiinfinite flat plate after passage of a shock wave and a trailing driver gas-driven gas interface. The problem has special application to expansion tube flows. The flow-governing equations have been transformed into the Lamcrocco variables. The numerical results indicate that a fully turbulent boundary layer relaxes faster to the final steady-state values of heat transfer and skin-friction than a fully laminar boundary layer.

  8. Identifying Fault Connections of the Southern Pacific-North American Plate Boundary Using Triggered Slip and Crustal Velocities

    Science.gov (United States)

    Donnellan, A.; Grant Ludwig, L.; Rundle, J. B.; Parker, J. W.; Granat, R.; Heflin, M. B.; Pierce, M. E.; Wang, J.; Gunson, M.; Lyzenga, G. A.

    2017-12-01

    The 2010 M7.2 El Mayor - Cucapah earthquake caused extensive triggering of slip on faults proximal to the Salton Trough in southern California. Triggered slip and postseismic motions that have continued for over five years following the earthquake highlight connections between the El Mayor - Cucapah rupture and the network of faults that branch out along the southern Pacific - North American Plate Boundary. Coseismic triggering follows a network of conjugate faults from the northern end of the rupture to the Coachella segment of the southernmost San Andreas fault. Larger aftershocks and postseismic motions favor connections to the San Jacinto and Elsinore faults further west. The 2012 Brawley Swarm can be considered part of the branching on the Imperial Valley or east side of the plate boundary. Cluster analysis of long-term GPS velocities using Lloyds Algorithm, identifies bifurcation of the Pacific - North American plate boundary; The San Jacinto fault joins with the southern San Andreas fault, and the Salton Trough and Coachella segment of the San Andreas fault join with the Eastern California Shear Zone. The clustering analysis does not identify throughgoing deformation connecting the Coachella segment of the San Andreas fault with the rest of the San Andreas fault system through the San Gorgonio Pass. This observation is consistent with triggered slip from both the 1992 Landers and 2010 El Mayor - Cucapah earthquakes that follows the plate boundary bifurcation and with paleoseismic evidence of smaller earthquakes in the San Gorgonio Pass.

  9. Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

    KAUST Repository

    Cheng, W.; Pullin, D. I.; Samtaney, Ravi

    2015-01-01

    © 2015 Cambridge University Press. We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which

  10. Experiments of dike-induced deformation: Insights on the long-term evolution of divergent plate boundaries

    KAUST Repository

    Trippanera, D.; Ruch, Joel; Acocella, V.; Rivalta, E.

    2015-01-01

    on the intrusion depth and thickness, consistently to what is observed along divergent plate boundaries. The early deformation in setups B and C is similar to that from a single rifting episode (i.e., Lakagigar, Iceland, and Dabbahu, Afar), whereas the late stages

  11. Global crustal movement and tectonic plate boundary deformation constrained by the ITRF2008

    Directory of Open Access Journals (Sweden)

    Zhu Ze

    2012-08-01

    Full Text Available On the basis of the newly released International Terrestrial Reference Frame(ITRF2008 by the International Earth Rotation Service (IERS, a new global plate model ITRF2008 plate for the major plates is established. This ITRF2008-derived model is analyzed in comparison with NNR-NUVEL1A model, which is mainly based on geological and geophysical data. The Eurasia and Pacific plates display obvious differences in terms of the velocity fields derived from the two plate motion models. Plate acceleration is also introduced to characterize the differences of the two velocity fields which obtained from ITRF2008 -plate and NNR-NUVEL1A models for major individual plates. The results show that the Africa, South America and Eurasia plates are undergoing acceleration, while the North America and Australia plates are in the state of deceleration motion.

  12. Effects of freestream on the characteristics of thermally-driven boundary layers along a heated vertical flat plate

    International Nuclear Information System (INIS)

    Abedin, Mohammad Zoynal; Tsuji, Toshihiro; Lee, Jinho

    2012-01-01

    Highlights: ► A time-developing direct numerical simulations are done for water along a heated vertical plate. ► The objective is to see the effects of free streams on the combined-convection boundary layers. ► There are no reports for water with direct numerical simulation in this regards. ► An experiment is also conducted on the transitional and turbulent boundary layer in water. ► This is to collect informations on the integral thickness of the velocity boundary layer. - Abstract: Time-developing thermally-driven boundary layers created by imposing aiding and opposing freestreams on the natural-convection boundary layer in water along a heated vertical flat plate have been examined with a direct numerical simulation to clarify their transition and turbulence behaviors. The numerical results for aiding flow reveal that the transition begins at a thick laminar boundary layer due to the delay of the transition and large-scale vortexes centering on the spanwise direction are followed, while, for opposing flow, the transition begins at a thin laminar boundary layer due to the quickening of the transition and relatively small-scale vortexes are generated with the progress of transition. To improve the significance of the present numerical results, the association of turbulence statistics between time- and space-developing flows has been investigated. Consequently, the numerical results for time-developing flow are converted to those for space-developing flow through the integral thickness of the velocity boundary layer for pure natural convection, and thus the regimes of boundary layer flows can be quantitatively assessed. Moreover, the turbulence statistics and the flow structures in the thermally-driven boundary layers are also presented.

  13. The EarthScope Plate Boundary Observatory: Bringing Low Latency Data From Unimak Island, Alaska

    Science.gov (United States)

    Feaux, K.; Mencin, D.; Jackson, M.; Gallaher, W.; Pauk, B.; Smith, S.

    2008-05-01

    The Plate Boundary Observatory (PBO), part of the NSF-funded EarthScope project, will complete the installation of a fourteen station GPS network on Unimak Island, Alaska in August, 2008. The primary data communications goal of the project is to design and implement a robust data communications network capable of downloading 15-sec daily GPS files and streaming 1 Hz GPS data, via Ustream, from Unimak Island to three data relay points in the Aleutian chain. As part of the permitting agreement with the landowner, PBO will co-locate the GPS stations with existing USGS seismic stations. The technical challenges involved in optimizing the data communications network for both the GPS data and the seismic data will be presented. From Unimak island, there will be three separate data telemetry paths: 1) West through a radio repeater on Akutan volcano to a VSAT in Akutan village, 2) East through a radio repeater to a T1 connection in Cold Bay, AK, 3) South through a radio repeater to a VSAT at an existing PBO GPS station in King Cove, AK. The difficulties involved in the project include complex network geometries with multiple radio repeaters, long distance RF transmission over water, hardware bandwidth limitations, power limitations, space limitations, as well as working in bear country on an incredibly remote and active volcano.

  14. Streamwise counter-rotating vortices generated by triangular leading edge pattern in flat plate boundary layer

    KAUST Repository

    Hasheminejad, S. M.; Mitsudharmadi, Hatsari; Winoto, S. H.; Lua, K. B.; Low, H. T.

    2016-01-01

    A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out

  15. Strength and Deformation Rate of Plate Boundaries: The Rheological Effects of Grain Size Reduction, Structure, and Serpentinization.

    Science.gov (United States)

    Montesi, L.; Gueydan, F.

    2016-12-01

    Global strain rate maps reveal 1000-fold contrasts between plate interiors, oceanic or continental diffuse plate boundaries and narrow plate boundaries. Here, we show that rheological models based on the concepts of shear zone localization and the evolution of rock structure upon strain can explain these strain rate contrasts. Ductile shear zones constitute a mechanical paradox in the lithosphere. As every plastic deformation mechanism is strain-rate-hardening, ductile rocks are expected to deform at low strain rate and low stress (broad zone of deformation). Localized ductile shear zones require either a localized forcing (locally high stress) or a thermal or structural anomaly in the shear zone; either can be inherited or develop progressively as rocks deform. We previously identified the most effective process at each depth level of the lithosphere. In the upper crust and middle crust, rocks fabric controls localization. Grain size reduction is the most efficient mechanism in the uppermost mantle. This analysis can be generalized to consider a complete lithospheric section. We assume strain rate does not vary with depth and that the depth-integrated strength of the lithospheric does not change over time, as the total force is controlled by external process such as mantle convection and plate and slab buoyancy. Reducing grain size from a coarse value typical of undeformed peridotite to a value in agreement with the stress level (piezometer) while letting that stress vary from depth to depth (the integrated stress remains the same) increases the lithospheric strain rate by about a factor of 1000. This can explain the development of diffuse plate boundaries. The slightly higher strain rate of continental plate boundary may reflect development of a layered rock fabric in the middle crust. Narrow plate boundaries require additional weakening process. The high heat flux near mid-ocean ridge implies a thin lithosphere, which enhances stress (for constant integrated

  16. Weak Tectono-Magmatic Relationships along an Obliquely Convergent Plate Boundary: Sumatra, Indonesia

    Directory of Open Access Journals (Sweden)

    Valerio Acocella

    2018-02-01

    Full Text Available The tectono-magmatic relationships along obliquely convergent plate boundaries, where strain partitioning promotes strike-slip structures along the volcanic arc, are poorly known. Here it is unclear if and, in case, how the strike-slip structures control volcanic processes, distribution and size. To better define the possible tectono-magmatic relationships along strike-slip arcs, we merge available information on the case study of Sumatra (Indonesia with field structural data. The Sumatra arc (entire volcanic belt consists of 48 active volcanoes. Of these, 46% lie within 10 km from the dextral Great Sumatra Fault (GSF, which carries most horizontal displacement on the overriding plate, whereas 27% lie at >20 km from the GSF. Among the volcanoes at <10 km from GSF, 48% show a possible structural relation to the GSF, whereas only 28% show a clear structural relation, lying in pull-aparts or releasing bends; these localized areas of transtension (local extensional zone do not develop magmatic segments. There is no relation between the GSF along-strike slip rate variations and the volcanic productivity. The preferred N30°-N40°E volcano alignment and elongation are subparallel to the convergence vector or to the GSF. The structural field data, collected in the central and southern GSF, show, in addition to the dextral motions along NW-SE to N-S striking faults, also normal motions (extending WNW-ESE or NE-SW, suggesting local reactivations of the GSF. Overall, the collected data suggest a limited tectonic control on arc volcanism. The tectonic control is mostly expressed by the mean depth of the slab surface below the volcanoes (130 ± 20 km and, subordinately, local extension along the GSF. The latter, when WNW-ESE oriented (more common, may be associated with the overall tectonic convergence, as suggested by the structural data; conversely, when NE-SW oriented (less common, the extension may result from co- and post-seismic arc normal extension

  17. A Geodetic Strain Rate Model for the Pacific-North American Plate Boundary, western United States

    Science.gov (United States)

    Kreemer, C.; Hammond, W. C.; Blewitt, G.; Holland, A. A.; Bennett, R. A.

    2012-04-01

    We present a model of crustal strain rates derived from GPS measurements of horizontal station velocities in the Pacific-North American plate boundary in the western United States. The model reflects a best estimate of present-day deformation from the San Andreas fault system in the west to the Basin and Range province in the east. Of the total 2,846 GPS velocities used in the model, 1,197 are derived by ourselves, and 1,649 are taken from (mostly) published results. The velocities derived by ourselves (the "UNR solution") are estimated from GPS position time-series of continuous and semi-continuous stations for which data are publicly available. We estimated ITRF2005 positions from 2002-2011.5 using JPL's GIPSY-OASIS II software with ambiguity resolution applied using our custom Ambizap software. Only stations with time-series that span at least 2.25 years are considered. We removed from the time-series continental-scale common-mode errors using a spatially-varying filtering technique. Velocity uncertainties (typically 0.1-0.3 mm/yr) assume that the time-series contain flicker plus white noise. We used a subset of stations on the stable parts of the Pacific and North American plates to estimate the Pacific-North American pole of rotation. This pole is applied as a boundary condition to the model and the North American - ITRF2005 pole is used to rotate our velocities into a North America fixed reference frame. We do not include parts of the time-series that show curvature due to post-seismic deformation after major earthquakes and we also exclude stations whose time-series display a significant unexplained non-linearity or that are near volcanic centers. Transient effects longer than the observation period (i.e., slow viscoelastic relaxation) are left in the data. We added to the UNR solution velocities from 12 other studies. The velocities are transformed onto the UNR solution's reference frame by estimating and applying a translation and rotation that minimizes

  18. Rheological structure of the lithosphere in plate boundary strike-slip fault zones

    Science.gov (United States)

    Chatzaras, Vasileios; Tikoff, Basil; Kruckenberg, Seth C.; Newman, Julie; Titus, Sarah J.; Withers, Anthony C.; Drury, Martyn R.

    2016-04-01

    How well constrained is the rheological structure of the lithosphere in plate boundary strike-slip fault systems? Further, how do lithospheric layers, with rheologically distinct behaviors, interact within the strike-slip fault zones? To address these questions, we present rheological observations from the mantle sections of two lithospheric-scale, strike-slip fault zones. Xenoliths from ˜40 km depth (970-1100 ° C) beneath the San Andreas fault system (SAF) provide critical constraints on the mechanical stratification of the lithosphere in this continental transform fault. Samples from the Bogota Peninsula shear zone (BPSZ, New Caledonia), which is an exhumed oceanic transform fault, provide insights on lateral variations in mantle strength and viscosity across the fault zone at a depth corresponding to deformation temperatures of ˜900 ° C. Olivine recrystallized grain size piezometry suggests that the shear stress in the SAF upper mantle is 5-9 MPa and in the BPSZ is 4-10 MPa. Thus, the mantle strength in both fault zones is comparable to the crustal strength (˜10 MPa) of seismogenic strike-slip faults in the SAF system. Across the BPSZ, shear stress increases from 4 MPa in the surrounding rocks to 10 MPa in the mylonites, which comprise the core of the shear zone. Further, the BPSZ is characterized by at least one order of magnitude difference in the viscosity between the mylonites (1018 Paṡs) and the surrounding rocks (1019 Paṡs). Mantle viscosity in both the BPSZ mylonites and the SAF (7.0ṡ1018-3.1ṡ1020 Paṡs) is relatively low. To explain our observations from these two strike-slip fault zones, we propose the "lithospheric feedback" model in which the upper crust and lithospheric mantle act together as an integrated system. Mantle flow controls displacement and the upper crust controls the stress magnitude in the system. Our stress data combined with data that are now available for the middle and lower crustal sections of other transcurrent fault

  19. Study of Boundary Layer Convective Heat Transfer with Low Pressure Gradient Over a Flat Plate Via He's Homotopy Perturbation Method

    International Nuclear Information System (INIS)

    Fathizadeh, M.; Aroujalian, A.

    2012-01-01

    The boundary layer convective heat transfer equations with low pressure gradient over a flat plate are solved using Homotopy Perturbation Method, which is one of the semi-exact methods. The nonlinear equations of momentum and energy solved simultaneously via Homotopy Perturbation Method are in good agreement with results obtained from numerical methods. Using this method, a general equation in terms of Pr number and pressure gradient (λ) is derived which can be used to investigate velocity and temperature profiles in the boundary layer.

  20. Fault and graben growth along active magmatic divergent plate boundaries in Iceland and Ethiopia

    KAUST Repository

    Trippanera, D.; Acocella, V.; Ruch, Joel; Abebe, B.

    2015-01-01

    Recent studies highlight the importance of annual-scale dike-induced rifting episodes in developing normal faults and graben along the active axis of magmatic divergent plate boundaries (MDPB). However, the longer-term (102-105 years) role of diking on the cumulative surface deformation and evolution of MDPB is not yet well understood. To better understand the longer-term normal faults and graben along the axis of MDPB, we analyze fissure swarms in Iceland and Ethiopia. We first focus on the simplest case of immature fissure swarms, with single dike-fed eruptive fissures; these consist of a <1 km wide graben bordered by normal faults with displacement up to a few meters, consistent with theoretical models and geodetic data. A similar structural pattern is found, with asymmetric and multiple graben, within wider mature fissure swarms, formed by several dike-fed eruptive fissures. We then consider the lateral termination of normal faults along these graben, to detect their upward or downward propagation. Most faults terminate as open fractures on flat surface, suggesting downward fault propagation; this is consistent with recent experiments showing dike-induced normal faults propagating downward from the surface. However, some normal faults also terminate as open fractures on monoclines, which resemble fault propagation folds; this suggests upward propagation of reactivated buried faults, promoted by diking. These results suggest that fault growth and graben development, as well as the longer-term evolution of the axis of MDPB, may be explained only through dike emplacement and that any amagmatic faulting is not necessary.

  1. The Plate Boundary Observatory Student Field Assistant Program in Southern California

    Science.gov (United States)

    Seider, E. L.

    2007-12-01

    Each summer, UNAVCO hires students as part of the Plate Boundary Observatory (PBO) Student Field Assistant Program. PBO, the geodetic component of the NSF-funded EarthScope project, involves the reconnaissance, permitting, installation, documentation, and maintenance of 880 permanent GPS stations in five years. During the summer 2007, nine students from around the US and Puerto Rico were hired to assist PBO engineers during the busy summer field season. From June to September, students worked closely with PBO field engineers to install and maintain permanent GPS stations in all regions of PBO, including Alaska. The PBO Student Field Assistant Program provides students with professional hands-on field experience as well as continuing education in the geosciences. It also gives students a glimpse into the increasing technologies available to the science community, the scope of geophysical research utilizing these technologies, and the field techniques necessary to complete this research. Students in the PBO Field Assistant Program are involved in all aspects of GPS support, including in-warehouse preparation and in-field installations and maintenance. Students are taught practical skills such as drilling, wiring, welding, hardware configuration, documentation, and proper field safety procedures needed to construct permanent GPS stations. These real world experiences provide the students with technical and professional skills that are not always available to them in a classroom, and will benefit them greatly in their future studies and careers. The 2007 summer field season in Southern California consisted of over 35 GPS permanent station installations. To date, the Southern California region of PBO has installed over 190 GPS stations. This poster presentation will highlight the experiences gained by the Southern California student field assistants, while supporting PBO- Southern California GPS installations in the Mohave Desert and the Inyo National Forest.

  2. Crustal Structure and Evolution of the Eastern Himalayan Plate Boundary System, Northeast India

    Science.gov (United States)

    Mitra, S.; Priestley, K. F.; Borah, Kajaljyoti; Gaur, V. K.

    2018-01-01

    We use data from 24 broadband seismographs located south of the Eastern Himalayan plate boundary system to investigate the crustal structure beneath Northeast India. P wave receiver function analysis reveals felsic continental crust beneath the Brahmaputra Valley, Shillong Plateau and Mikir Hills, and mafic thinned passive margin transitional crust (basement layer) beneath the Bengal Basin. Within the continental crust, the central Shillong Plateau and Mikir Hills have the thinnest crust (30 ± 2 km) with similar velocity structure, suggesting a unified origin and uplift history. North of the plateau and Mikir Hills the crustal thickness increases sharply by 8-10 km and is modeled by ˜30∘ north dipping Moho flexure. South of the plateau, across the ˜1 km topographic relief of the Dawki Fault, the crustal thickness increases abruptly by 12-13 km and is modeled by downfaulting of the plateau crust, overlain by 13-14 km thick sedimentary layer/rocks of the Bengal Basin. Farther south, beneath central Bengal Basin, the basement layer is thinner (20-22 km) and has higher Vs (˜4.1 km s-1) indicating a transitional crystalline crust, overlain by the thickest sedimentary layer/rocks (18-20 km). Our models suggest that the uplift of the Shillong Plateau occurred by thrust faulting on the reactivated Dawki Fault, a continent margin paleorift fault, and subsequent back thrusting on the south dipping Oldham Fault, in response to flexural loading of the Eastern Himalaya. Our estimated Dawki Fault offset combined with timing of surface uplift of the plateau reveals a reasonable match between long-term uplift and convergence rate across the Dawki Fault with present-day GPS velocities.

  3. Fault and graben growth along active magmatic divergent plate boundaries in Iceland and Ethiopia

    KAUST Repository

    Trippanera, D.

    2015-10-08

    Recent studies highlight the importance of annual-scale dike-induced rifting episodes in developing normal faults and graben along the active axis of magmatic divergent plate boundaries (MDPB). However, the longer-term (102-105 years) role of diking on the cumulative surface deformation and evolution of MDPB is not yet well understood. To better understand the longer-term normal faults and graben along the axis of MDPB, we analyze fissure swarms in Iceland and Ethiopia. We first focus on the simplest case of immature fissure swarms, with single dike-fed eruptive fissures; these consist of a <1 km wide graben bordered by normal faults with displacement up to a few meters, consistent with theoretical models and geodetic data. A similar structural pattern is found, with asymmetric and multiple graben, within wider mature fissure swarms, formed by several dike-fed eruptive fissures. We then consider the lateral termination of normal faults along these graben, to detect their upward or downward propagation. Most faults terminate as open fractures on flat surface, suggesting downward fault propagation; this is consistent with recent experiments showing dike-induced normal faults propagating downward from the surface. However, some normal faults also terminate as open fractures on monoclines, which resemble fault propagation folds; this suggests upward propagation of reactivated buried faults, promoted by diking. These results suggest that fault growth and graben development, as well as the longer-term evolution of the axis of MDPB, may be explained only through dike emplacement and that any amagmatic faulting is not necessary.

  4. Structure and composition of the plate-boundary slip zone for the 2011 Tohoku-Oki earthquake.

    Science.gov (United States)

    Chester, Frederick M; Rowe, Christie; Ujiie, Kohtaro; Kirkpatrick, James; Regalla, Christine; Remitti, Francesca; Moore, J Casey; Toy, Virginia; Wolfson-Schwehr, Monica; Bose, Santanu; Kameda, Jun; Mori, James J; Brodsky, Emily E; Eguchi, Nobuhisa; Toczko, Sean

    2013-12-06

    The mechanics of great subduction earthquakes are influenced by the frictional properties, structure, and composition of the plate-boundary fault. We present observations of the structure and composition of the shallow source fault of the 2011 Tohoku-Oki earthquake and tsunami from boreholes drilled by the Integrated Ocean Drilling Program Expedition 343 and 343T. Logging-while-drilling and core-sample observations show a single major plate-boundary fault accommodated the large slip of the Tohoku-Oki earthquake rupture, as well as nearly all the cumulative interplate motion at the drill site. The localization of deformation onto a limited thickness (less than 5 meters) of pelagic clay is the defining characteristic of the shallow earthquake fault, suggesting that the pelagic clay may be a regionally important control on tsunamigenic earthquakes.

  5. Boundary Layer Flow and Heat Transfer with Variable Fluid Properties on a Moving Flat Plate in a Parallel Free Stream

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    2012-01-01

    Full Text Available The steady boundary layer flow and heat transfer of a viscous fluid on a moving flat plate in a parallel free stream with variable fluid properties are studied. Two special cases, namely, constant fluid properties and variable fluid viscosity, are considered. The transformed boundary layer equations are solved numerically by a finite-difference scheme known as Keller-box method. Numerical results for the flow and the thermal fields for both cases are obtained for various values of the free stream parameter and the Prandtl number. It is found that dual solutions exist for both cases when the fluid and the plate move in the opposite directions. Moreover, fluid with constant properties shows drag reduction characteristics compared to fluid with variable viscosity.

  6. DNS of heat transfer in transitional, accelerated boundary layer flow over a flat plate affected by free-stream fluctuations

    International Nuclear Information System (INIS)

    Wissink, Jan G.; Rodi, Wolfgang

    2009-01-01

    Direct numerical simulations (DNS) of flow over and heat transfer from a flat plate affected by free-stream fluctuations were performed. A contoured upper wall was employed to generate a favourable streamwise pressure gradient along a large portion of the flat plate. The free-stream fluctuations originated from a separate LES of isotropic turbulence in a box. In the laminar portions of the accelerating boundary layer flow the formation of streaks was observed to induce an increase in heat transfer by the exchange of hot fluid near the surface of the plate and cold fluid from the free-stream. In the regions where the streamwise pressure gradient was only mildly favourable, intermittent turbulent spots were detected which relaminarised downstream as the streamwise pressure gradient became stronger. The relaminarisation of the turbulent spots was reflected by a slight decrease in the friction coefficient, which converged to its laminar value in the region where the streamwise pressure gradient was strongest.

  7. Dynamic Stress Concentration at the Boundary of an Incision at the Plate Under the Action of Weak Shock Waves

    Directory of Open Access Journals (Sweden)

    Mikulich Olena

    2017-09-01

    Full Text Available This paper proposes the novel technique for analysis of dynamic stress state of multi-connected infinite plates under the action of weak shock waves. For solution of the problem it uses the integral and discrete Fourier transforms. Calculation of transformed dynamic stresses at the incisions of plates is held using the boundary-integral equation method and the theory of complex variable functions. The numerical implementation of the developed algorithm is based on the method of mechanical quadratures and collocation technique. For calculation of originals of the dynamic stresses it uses modified discrete Fourier transform. The algorithm is effective in the analysis of the dynamic stress state of defective plates.

  8. Boundary layer on a flat plate with suction; Couche limite sur paroi plane poreuse avec aspiration

    Energy Technology Data Exchange (ETDEWEB)

    Favre, A; Dumas, R; Verollet, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Institut de Mecanique Statistique de la Turbulence, Faculte des Sciences de Marseille, 13 (France)

    1961-07-01

    This research done in wind tunnel concerns the turbulent boundary layer of a porous flat plate with suction. The porous wall is 1 m long and begins 1 m downstream of the leading edge. The Reynolds number based on the boundary layer thickness is of the order of 16.300. The suction rate defined as the ratio of the velocity perpendicular to the wall to the external flow velocity ranges from 0 to 2 per cent. The pressure gradient can be controlled. The mean velocity profiles have been determined for various positions and suction rates by means of total pressure probes together with the intensities of the turbulent velocity fluctuations components, energy spectra and correlations by means of hot wire anemometers, spectral analyser and correlator. The stream lines, the values of the viscous and turbulent shear stresses, of the local wall friction, of the turbulent energy production term, with some information on the dissipation of the energy have been derived from these measurements. For these data the integral of equation of continuity in boundary layer have been drawn. The suction effects on the boundary layer are important. The suction thoroughly alters the mean velocity profiles by increasing the viscous shear stresses near the wall and decreasing them far from the wall, it diminishes the longitudinal and transversal turbulence intensities, the turbulent shear stresses, and the production of energy of turbulence. These effects are much stressed in the inner part of the boundary layer. On the other hand the energy spectra show that the turbulence scale is little modified, the boundary layer thickness being not much diminished by the suction. The suction effects can be appreciated by comparing twice the suction rate to the wall friction coefficient (assumed airtight), quite noticeable as soon as the rate is about unity, they become very important when it reaches ten. (author) [French] Ces recherches, effectuees en soufflerie, concernent la couche limite turbulente d

  9. Unsteady heat-flux measurements of second-mode instability waves in a hypersonic flat-plate boundary layer

    Science.gov (United States)

    Kegerise, Michael A.; Rufer, Shann J.

    2016-08-01

    In this paper, we report on the application of the atomic layer thermopile (ALTP) heat-flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat-plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors, and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are consistent with data previously reported in the literature. Heat flux time series, and the Morlet wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was used to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

  10. Spatial distribution and offshore export of total organic carbon along the eastern boundary of the Subtropical North Pacific

    Directory of Open Access Journals (Sweden)

    C.G. Castro

    2011-12-01

    Full Text Available Data collected in February, 2003, along the upper continental slope of western North America between Monterey Bay, California (37°N, 122°W, and Cabo San Lucas, Mexico (23°N, 118°W, document, for the first time, the alongshore distribution of total organic carbon (TOC. Highest TOC concentrations (>70 µM were observed for waters above the nitracline and associated with both California Current and southern surface waters. The northward advection of tropical waters in the California Undercurrent did not have any discernible impact on TOC distributions. An estimate of the average rate at which TOC in surface waters was exported offshore by Ekman transport in February 2003 was 1.73 × 103 kg C yr−1 for each meter of coastline. The offshore flux estimate is thought to be conservative with respect to the annual mean offshore flux because the offshore Ekman transport and primary production increase in late spring and early summer and the contribution of upwelling filaments has not been considered. Analysis of TOC contributions to pelagic respiration suggested that TOC accounted for 45% of the oxygen decrease in southern oxic waters. In California Current and oxygen minimum zone waters, TOC did not contribute to pelagic respiration.

  11. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Directory of Open Access Journals (Sweden)

    Abid Hussanan

    Full Text Available In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  12. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Science.gov (United States)

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  13. Studying the active deformation of distributed plate boundaries by integration of GNSS networks

    Science.gov (United States)

    D'Agostino, Nicola; Avallone, Antonio; Cecere, Gianpaolo; D'Anastasio, Elisabetta

    2013-04-01

    In the last decade GNSS networks installed for different purposes have proliferated in Italy and now provide a large amount of data available to geophysical studies. In addition to the existing regional and nation-wide scientific GNSS networks developed by ASI (http://geodaf.mt.asi.it), INGV (http://ring.gm.ingv.it) and OGS (http://crs.inogs.it/frednet), a large number (> 400) of continuously-operating GPS stations have been installed in the framework of regional and national networks, both publicly-operated and commercial, developed to provide real-time positioning capability to surveyors. Although the quality of the data and metadata associated to these stations is generally lower with respect to the "scientific" CGPS stations, the increased density and redundancy in crustal motion information, resulting in more than 500 stations with more than 2.5 years of observations, significantly increase the knowledge of the active deformation of the Italian territory and provides a unique image of the crustal deformation field. The obtained GPS velocity field is analysed and various features ranging from the definition of strain distribution and microplate kinematics within the plate boundary, to the evaluation of tectonic strain accumulation on active faults are presented in this work. Undeforming, aseismic regions (Sardinia, Southern Apulia) provide test sites to evaluate the lower bound on the accuracy achievable to measure tectonic deformation. Integration of GNSS networks significantly improves the resolution of the strain rate field in Central Italy showing that active deformation is concentrated in a narrow belt along the crest of the Apennines, consistently with the distribution of the largest historical and recent earthquakes. Products derived from dense GPS velocity and strain rate fields include map of earthquake potential developed under the assumption that the rate of seismic moment accumulation measured from geodesy distributes into earthquake sizes that

  14. Hydrodynamic forces on heave plates for offshore systems oscillating close to the seabed or the free surface

    OpenAIRE

    Garrido Mendoza, Carlos Ariel

    2015-01-01

    La energía eólica marina es uno de los recursos energéticos con mayor proyección pudiendo contribuir a reducir el consumo de combustibles fósiles y a cubrir la demanda de energía en todo el mundo. El concepto de aerogenerador marino está basado en estructuras fijas como jackets o en plataformas flotantes, ya sea una semisumergible o una TLP. Se espera que la energía eólica offshore juegue un papel importante en el perfil de producción energética de los próximos años; por tanto, las turbinas e...

  15. The analysis of bainitic ferrite microstructure in microalloyed plate steels through quantitative characterization of intervariant boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Singon, E-mail: sikang@mines.edu [Advanced Steel Processing and Products Research Center, Colorado School of Mines, Golden, CO 80401 (United States); Speer, John G.; Regier, Ryan W. [Advanced Steel Processing and Products Research Center, Colorado School of Mines, Golden, CO 80401 (United States); Nako, Hidenori [Advanced Steel Processing and Products Research Center, Colorado School of Mines, Golden, CO 80401 (United States); Materials Research Laboratory, Kobe Steel Ltd., Kobe, Hyogo 651-2271 (Japan); Kennett, Shane C. [Advanced Steel Processing and Products Research Center, Colorado School of Mines, Golden, CO 80401 (United States); Exponent Failure Analysis Associates, Menlo Park, CA 94025 (United States); Findley, Kip O. [Advanced Steel Processing and Products Research Center, Colorado School of Mines, Golden, CO 80401 (United States)

    2016-07-04

    Electron backscatter diffraction (EBSD) measurements were performed to investigate the bainitic ferrite microstructure in low-carbon, microalloyed steels with varying C and Mn contents. Fully austenitized samples were isothermally heat treated at temperatures ranging from 450 to 550 °C to form bainitic ferrite. The bainitic ferrite microstructures and boundary characteristics obtained from the EBSD measurements were analyzed based on an inferred Kurdjumov-Sachs (K-S) orientation relationship. The heat treated samples exhibit a microstructure composed of laths and the lath aspect ratio tends to increase at lower isothermal heat treatment temperatures. High fractions of boundary misorientation angles below 5° are observed, which are due to lath boundaries in the microstructure. Additionally, misorientations of approximately 7°, 53° and 60° are observed, which are related to the sub-block, packet, and block boundaries, respectively. With decreasing isothermal heat treatment temperature, there is an increase of block boundaries; these boundaries are intervariant boundaries between different blocks within a packet, most of which have the misorientation angle of 60°. The specimens with a higher carbon level contained increased length of block boundaries, whereas the addition of Mn moderated the dependence of block boundary length on the heat treatment temperature within the experimental temperature range. Meanwhile, the length of intervariant boundaries of both packet and sub-block character did not vary much with heat treatment temperature and alloy composition.

  16. A New Estimate for Total Offset on the Southern San Andreas Fault: Implications for Cumulative Plate Boundary Shear in the Northern Gulf of California

    Science.gov (United States)

    Darin, M. H.; Dorsey, R. J.

    2012-12-01

    Development of a consistent and balanced tectonic reconstruction for the late Cenozoic San Andreas fault (SAF) in southern California has been hindered for decades by incompatible estimates of total dextral offset based on different geologic cross-fault markers. The older estimate of 240-270 km is based on offset fluvial conglomerates of the middle Miocene Mint Canyon and Caliente Formations west of the SAF from their presumed source area in the northern Chocolate Mountains NE of the SAF (Ehlig et al., 1975; Ehlert, 2003). The second widely cited offset marker is a distinctive Triassic megaporphyritic monzogranite that has been offset 160 ± 10 km between Liebre Mountain west of the SAF and the San Bernadino Mountains (Matti and Morton, 1993). In this analysis we use existing paleocurrent data and late Miocene clockwise rotation in the eastern Transverse Ranges (ETR) to re-assess the orientation of the piercing line used in the 240 km-correlation, and present a palinspastic reconstruction that satisfies all existing geologic constraints. Our reconstruction of the Mint Canyon piercing line reduces the original estimate of 240-270 km to 195 ± 15 km of cumulative right-lateral slip on the southern SAF (sensu stricto), which is consistent with other published estimates of 185 ± 20 km based on correlative basement terranes in the Salton Trough region. Our estimate of ~195 km is consistent with the lower estimate of ~160 km on the Mojave segment because transform-parallel extension along the southwestern boundary of the ETR during transrotation produces ~25-40 km of displacement that does not affect offset markers of the Liebre/San Bernadino correlation located northwest of the ETR rotating domain. Reconciliation of these disparate estimates places an important new constraint on the total plate boundary shear that is likely accommodated in the adjacent northern Gulf of California. Global plate circuit models require ~650 km of cumulative Pacific-North America (PAC

  17. Pyrolysis and Boundary Layer Combustion of a Non-Charring Solid Plate Under Forced Flow

    National Research Council Canada - National Science Library

    Ananth, Ramagopal

    2003-01-01

    Solutions of Navier-Stokes (NS) equations were obtained for burning rate Nu and temperature distributions for a flat PMMA plate using an iterative method to impose steady-state, pyrolysis kinetics at the surface...

  18. Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

    KAUST Repository

    Cheng, W.

    2015-11-11

    © 2015 Cambridge University Press. We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the time- and space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number Reθ based on the momentum boundary-layer thickness θ. Comparison with data from the first case at demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, Reθ, the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger Reθ = 11000 of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.

  19. Effects of Thermal Radiation and Chemical Reaction on MHD Free Convection Flow past a Flat Plate with Heat Source and Convective Surface Boundary Condition

    OpenAIRE

    E.Hemalatha; N. Bhaskar Reddy

    2015-01-01

    This paper analyzes the radiation and chemical reaction effects on MHD steady two-dimensional laminar viscous incompressible radiating boundary layer flow over a flat plate in the presence of internal heat generation and convective boundary condition. It is assumed that lower surface of the plate is in contact with a hot fluid while a stream of cold fluid flows steadily over the upper surface with a heat source that decays exponentially. The Rosseland approximation is used to desc...

  20. Plate Boundary Observatory Infrastructure and Data Products in Education and Outreach

    Science.gov (United States)

    Eriksson, S. C.; Barbour, K.; Lee, E.

    2005-12-01

    As one of three major components of NSF's EarthScope program, the Plate Boundary Observatory (PBO) encourages the integration of research and education. Informing various communities about the current work of PBO and the scientific discoveries related to the use of this instrumentation has contributed to the success of PBO during the first two years of the EarthScope project. UNAVCO(PBO), IRIS (USArray), and the EarthScope project office work together to integrate Education and Outreach (E&O) opportunities into a program that is greater than the sum of its parts and yet maintains the identity of each organization. Building and maintaining the PBO website, documenting and archiving activities of PBO, providing short courses for professional development of scientists using EarthScope data, and developing higher level data products with an appropriate educational framework are a few of the activities that provide both challenges and opportunities. The internet, particularly the World Wide Web, has become the primary tool for disseminating information to various audiences. The primary goals of the PBO website are to provide current information on the progress of GPS and Strainmeter facility construction; to provide access to different levels of data products; and to facilitate networking with and among scientists. Challenges for the PBO website include publishing current stories on installation projects while coordinating with field engineers on a regular basis; providing near to real time updates and maintaining quality assurance processes; and defining personnel requirements for a maintaining a dynamic website. Currently, archived photographs, web diaries, and numerous web highlights document PBO's success and provide a visual record of PBO's accomplishments and behind-the-scene activities over the last two years. The community charged PBO with increasing the number of scientists using its data. UNAVCO does this by providing short courses for professional development

  1. Locating seismicity on the Arctic plate boundary using multiple-event techniques and empirical signal processing

    Science.gov (United States)

    Gibbons, S. J.; Harris, D. B.; Dahl-Jensen, T.; Kværna, T.; Larsen, T. B.; Paulsen, B.; Voss, P. H.

    2017-12-01

    The oceanic boundary separating the Eurasian and North American plates between 70° and 84° north hosts large earthquakes which are well recorded teleseismically, and many more seismic events at far lower magnitudes that are well recorded only at regional distances. Existing seismic bulletins have considerable spread and bias resulting from limited station coverage and deficiencies in the velocity models applied. This is particularly acute for the lower magnitude events which may only be constrained by a small number of Pn and Sn arrivals. Over the past two decades there has been a significant improvement in the seismic network in the Arctic: a difficult region to instrument due to the harsh climate, a sparsity of accessible sites (particularly at significant distances from the sea), and the expense and difficult logistics of deploying and maintaining stations. New deployments and upgrades to stations on Greenland, Svalbard, Jan Mayen, Hopen, and Bjørnøya have resulted in a sparse but stable regional seismic network which results in events down to magnitudes below 3 generating high-quality Pn and Sn signals on multiple stations. A catalogue of several hundred events in the region since 1998 has been generated using many new phase readings on stations on both sides of the spreading ridge in addition to teleseismic P phases. A Bayesian multiple event relocation has resulted in a significant reduction in the spread of hypocentre estimates for both large and small events. Whereas single event location algorithms minimize vectors of time residuals on an event-by-event basis, the Bayesloc program finds a joint probability distribution of origins, hypocentres, and corrections to traveltime predictions for large numbers of events. The solutions obtained favour those event hypotheses resulting in time residuals which are most consistent over a given source region. The relocations have been performed with different 1-D velocity models applicable to the Arctic region and

  2. Predictions of the effect of stratification on superimposed forced and free convection between vertical parallel plates for various boundary conditions

    International Nuclear Information System (INIS)

    Cowan, G.H.; Irvine, T.J. Jr.; Quarini, G.L.

    1983-01-01

    The velocity and temperature equations for laminar buoyancy and forced convection flows between vertical flat parallel plates are presented. The thermal boundary conditions on the plate define the buoyancy driven field, while the channel Reynolds number defines the forced flow field. Specific examples relating to tall narrow channels with laminar convention and to closed high ratio cavities (as may be found in the proposed active and passive insulation systems for sodium cooled fast reactors) are presented. The analysis is limited to the laminar flow regimes, whilst some reactor situations are likely to be turbulent, hence a proposal for a simple extension of this analysis to the turbulent regime is made. It is shown how the analysis can be made to apply to fluids of various Prandtl numbers. (author)

  3. Upper-Mantel Earthquakes in the Australia-Pacific Plate Boundary Zone and the Roots of the Alpine Fault

    Science.gov (United States)

    Boese, C. M.; Warren-Smith, E.; Townend, J.; Stern, T. A.; Lamb, S. H.

    2016-12-01

    Seismicity in the upper mantle in continental collision zones is relatively rare, but observed around the world. Temporary seismometer deployments have repeatedly detected mantle earthquakes at depths of 40-100 km within the Australia-Pacific plate boundary zone beneath the South Island of New Zealand. Here, the transpressive Alpine Fault constitutes the primary plate boundary structure linking subduction zones of opposite polarity farther north and south. The Southern Alps Microearthquake Borehole Array (SAMBA) has been operating continuously since November 2008 along a 50 km-long section of the central Alpine Fault, where the rate of uplift of the Southern Alps is highest. To date it has detected more than 40 small to moderate-sized mantle events (1≤ML≤3.9). The Central Otago Seismic Array (COSA) has been in operation since late 2012 and detected 15 upper mantle events along the sub-vertical southern Alpine Fault. Various mechanisms have been proposed to explain the occurrence of upper mantle seismicity in the South Island, including intra-continental subduction (Reyners 1987, Geology); high shear-strain gradients due to depressed geotherms and viscous deformation of mantle lithosphere (Kohler and Eberhart-Phillips 2003, BSSA); high strain rates resulting from plate bending (Boese et al. 2013, EPSL), and underthrusting of the Australian plate (Lamb et al. 2015, G3). Focal mechanism analysis reveals a variety of mechanisms for the upper mantle events but predominantly strike-slip and reverse faulting. In this study, we apply spectral analysis to better constrain source parameters for these mantle events. These results are interpreted in conjunction with new information about crustal structure and low-frequency earthquakes near the Moho and in light of existing velocity, attenuation and resistivity models.

  4. Offshore Rayleigh Group Velocity Observations of the South Island, New Zealand, from Ambient Noise Data

    KAUST Repository

    Yeck, William L.; Sheehan, Anne F.; Stachnik, Joshua C.; Lin, Fan-Chi

    2017-01-01

    We present azimuthally anisotropic Rayleigh group velocity models from 8 - 35 s both offshore and onshore of the South Island of New Zealand. We use MOANA (Marine Observations of Anisotropy Near Aotearoa) broadband ocean seismic data in combination with on land data from the New Zealand National Seismography Network (NZNSN) to investigate the seismic structure of the flanks of the Australian-Pacific plate boundary. At 8 s, we observe low offshore group velocities best explained by the influence of the water layer and thick water-laden sediments. At long periods (20-30 s), group velocities are lower on the South Island relative to its offshore flanks, due to thickened crust beneath the island, with the lowest velocities primarily beneath the Southern Alps. Group velocity azimuthal anisotropy fast directions near the Alpine Fault align with the direction of relative plate motion between the Australian and Pacific plates. In the southern portion of the island, fast directions rotate anticlockwise, likely in response to a decrease in dextral shearing away from the plate boundary. Azimuthal anisotropy fast directions align with absolute plate motion offshore on the Pacific plate. Based on the depth sensitivity of our observations, we suggest diffuse deformation occurs throughout the crust. Our observations match trends in previous Pn anisotropy and SKS shear wave splitting observations, and therefore suggest a consistent pattern of distributed deformation throughout the lithosphere.

  5. Offshore Rayleigh Group Velocity Observations of the South Island, New Zealand, from Ambient Noise Data

    KAUST Repository

    Yeck, William L.

    2017-02-15

    We present azimuthally anisotropic Rayleigh group velocity models from 8 - 35 s both offshore and onshore of the South Island of New Zealand. We use MOANA (Marine Observations of Anisotropy Near Aotearoa) broadband ocean seismic data in combination with on land data from the New Zealand National Seismography Network (NZNSN) to investigate the seismic structure of the flanks of the Australian-Pacific plate boundary. At 8 s, we observe low offshore group velocities best explained by the influence of the water layer and thick water-laden sediments. At long periods (20-30 s), group velocities are lower on the South Island relative to its offshore flanks, due to thickened crust beneath the island, with the lowest velocities primarily beneath the Southern Alps. Group velocity azimuthal anisotropy fast directions near the Alpine Fault align with the direction of relative plate motion between the Australian and Pacific plates. In the southern portion of the island, fast directions rotate anticlockwise, likely in response to a decrease in dextral shearing away from the plate boundary. Azimuthal anisotropy fast directions align with absolute plate motion offshore on the Pacific plate. Based on the depth sensitivity of our observations, we suggest diffuse deformation occurs throughout the crust. Our observations match trends in previous Pn anisotropy and SKS shear wave splitting observations, and therefore suggest a consistent pattern of distributed deformation throughout the lithosphere.

  6. Coupled effects of director orientations and boundary conditions on light induced bending of monodomain nematic liquid crystalline polymer plates

    International Nuclear Information System (INIS)

    You, Yue; Ding, Shurong; Huo, Yongzhong; Xu, Changwei

    2012-01-01

    A photo-chromic liquid crystal polymers (LCPs) is a smart material for large light-activated variation or bending to transfer luminous energy into mechanical energy. We study the light induced behavior by modeling planar and homeotropic nematic network polymer plates. We effectively illustrate some reported experimental outcomes and theoretically predict some possible bending patterns. This paper constructs an understanding between the bending behaviors and interactions among the alignments, aspect ratios and boundary conditions, etc. Our work provides information on optimizing light induced bending in the process of micro-opto-mechanical system (MOMS) design. (paper)

  7. Hall effects on free convection hydromagnetic boundary layer flow of Rivlin-Ericksen fluid past a vertical plate

    International Nuclear Information System (INIS)

    Jha, P.K.

    1986-01-01

    An attempt has been made to study the problem of free convection hydromagnetic flow of an elastico-viscous fluid past a porous vertical plate in a rotating frame of reference taking ohmic and viscous dissipations into account in the presence of Hall current. The nature of velocity profile shows the existence of multiple boundary layers. Their 'thickness' is seen to decrease with increasing values of Ekman, Hartman and Prandtl numbers and Hall parameter. The graphical study reveals that the increasing values of Hall parameter and Ekman number (for a fixed large value of Hall parameter) exert opposite influence on the flow. (author). 11 refs., 2 tables

  8. An experimental investigation of laminar free convection from a vertical flat plate at general boundary condition

    International Nuclear Information System (INIS)

    Aharon, J.; Lahav, C.; Kalman, H.; Shai, I.

    1996-01-01

    The present work deals with natural convection on a vertical flat plate, where one side of the plate is exposed to an environment of constant temperature - T a , with which heat is exchanged at an effective heat transfer coefficient, Glen. The other side of the plate is exposed to a fluid at a different temperature -T ∞ . The temperature gradient induces a natural convection in the fluid. The present investigation treats the heat transfer problem in the laminar cone in air (P r =1). An experimental apparatus has been constructed to confirm the heat transfer features predicted analytically in previous work. The local experimental Nusselt number was correlated with the modified Rayleigh number, for the laminar range. (authors)

  9. Stress Transfer Processes during Great Plate Boundary Thrusting Events: A Study from the Andaman and Nicobar Segments

    Science.gov (United States)

    Andrade, V.; Rajendran, K.

    2010-12-01

    The response of subduction zones to large earthquakes varies along their strike, both during the interseismic and post-seismic periods. The December 26, 2004 earthquake nucleated at 3° N latitude and its rupture propagated northward, along the Andaman-Sumatra subduction zone, terminating at 15°N. Rupture speed was estimated at about 2.0 km per second in the northern part under the Andaman region and 2.5 - 2.7 km per second under southern Nicobar and North Sumatra. We have examined the pre and post-2004 seismicity to understand the stress transfer processes within the subducting plate, in the Andaman (10° - 15° N ) and Nicobar (5° - 10° N) segments. The seismicity pattern in these segments shows distinctive characteristics associated with the outer rise, accretionary prism and the spreading ridge, all of which are relatively better developed in the Andaman segment. The Ninety East ridge and the Sumatra Fault System are significant tectonic features in the Nicobar segment. The pre-2004 seismicity in both these segments conform to the steady-state conditions wherein large earthquakes are fewer and compressive stresses dominate along the plate interface. Among the pre-2004 great earthquakes are the 1881 Nicobar and 1941 Andaman events. The former is considered to be a shallow thrust event that generated a small tsunami. Studies in other subduction zones suggest that large outer-rise tensional events follow great plate boundary breaking earthquakes due to the the up-dip transfer of stresses within the subducting plate. The seismicity of the Andaman segment (1977-2004) concurs with the steady-state stress conditions where earthquakes occur dominantly by thrust faulting. The post-2004 seismicity shows up-dip migration along the plate interface, with dominance of shallow normal faulting, including a few outer rise events and some deeper (> 100 km) strike-slip faulting events within the subducting plate. The September 13, 2002, Mw 6.5 thrust faulting earthquake at

  10. Free Convection over a Permeable Horizontal Flat Plate Embedded in a Porous Medium with Radiation Effects and Mixed Thermal Boundary Conditions

    OpenAIRE

    Najiyah S. Khasi'ie; Roziena Khairuddin; Najihah Mohamed; Mohd Zuki Salleh; Roslinda Nazar; Ioan Pop

    2012-01-01

    Problem statement: In this study, the mathematical modeling of free convection boundary layer flow over a permeable horizontal flat plate embedded in a porous medium under mixed thermal boundary conditions and radiation effects is considered. Approach: The transformed boundary layer equations are solved numerically using the shooting method. Results: Numerical solutions are obtained for the wall temperature, the heat transfer coefficient, as well as the velocity and temperature profiles. The ...

  11. Boundary integral equation methods in eigenvalue problems of elastodynamics and thin plates

    CERN Document Server

    Kitahara, M

    1985-01-01

    The boundary integral equation (BIE) method has been used more and more in the last 20 years for solving various engineering problems. It has important advantages over other techniques for numerical treatment of a wide class of boundary value problems and is now regarded as an indispensable tool for potential problems, electromagnetism problems, heat transfer, fluid flow, elastostatics, stress concentration and fracture problems, geomechanical problems, and steady-state and transient electrodynamics.In this book, the author gives a complete, thorough and detailed survey of the method. It pro

  12. Experiments of dike-induced deformation: Insights on the long-term evolution of divergent plate boundaries

    KAUST Repository

    Trippanera, D.

    2015-10-22

    The shallow transport of magma occurs through dikes causing surface deformation. Our understanding of the effects of diking at the surface is limited, especially on the long term, for repeated intrusive episodes. We use analogue models to study the upper crustal deformation induced by dikes. We insert metal plates within cohesive sand with three setups: in setup A, the intrusion rises upward with constant thickness and in setups B and C, the intrusion thickens at a fixed depth, with final rectangular (setup B) or triangular (setup C) shape in section. Setup A creates a doming delimited by reverse faults, with secondary apical graben, without close correspondence in nature. In setups B and C, a depression flanked by two uplifted areas is bordered by inward dipping normal faults propagating downward and, for deeper intrusions in setup B, also by inner faults, reverse at the surface; this deformation is similar to what is observed in nature, suggesting a consistent physical behavior. Dikes in nature initially propagate developing a mode I fracture at the tip, subsequently thickened by magma intrusion, without any host rock translation in the propagation direction (as in setup A). The deformation pattern in setups B and C depends on the intrusion depth and thickness, consistently to what is observed along divergent plate boundaries. The early deformation in setups B and C is similar to that from a single rifting episode (i.e., Lakagigar, Iceland, and Dabbahu, Afar), whereas the late stages resemble the structure of mature rifts (i.e., Krafla, Iceland), confirming diking as a major process in shaping divergent plate boundaries.

  13. Shear flow beneath oceanic plates: Local nonsimilarity boundary layers for olivine rheology

    International Nuclear Information System (INIS)

    Yuen, D.A.; Tovish, A.; Schubert, G.

    1978-01-01

    The principle of local similarity, which has been used to model the two-dimensional boundary layers in the oceanic upper mantle, permits calculation of the temperature, velocity, and stress fields with essentially analytic techniques. Finite difference numerical methods are hard pressed to resolve the detail required by the large variation of viscosity between the lithosphere and the asthenosphere. In this paper the local similarity approximation has been justified by quantitatively evaluating the effect of nonsimilarity due to viscous heating, nonlinear temperature- and pressure-dependent rheology, buoyancy, adiabatic cooling, etc. Nonsimilar effects produce only small modifications of the locally similar boundary layers; important geophysical observables such as surface heat flux and ocean floor topography are given to better than 10% by the locally similar solution. A posteriori evaluations of the term neglected in the boundary layer simplification of the complete equations have been conducted on the locally similar temperature and velocity profiles close to the spreading ridge. The boundary layer models are valid to depths of 100 km at 3 m.y. and 10 km at 0.3 m.y

  14. Large Eddy Simulation of Supersonic Boundary Layer Transition over a Flat-Plate Based on the Spatial Mode

    Directory of Open Access Journals (Sweden)

    Suozhu Wang

    2014-02-01

    Full Text Available The large eddy simulation (LES of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 is performed in the present work. The Favre-filtered Navier-Stokes equations are used to simulate large scales, while a dynamic mixed subgrid-scale (SGS model is used to simulate subgrid stress. The convective terms are discretized with a fifth-order upwind compact difference scheme, while a sixth-order symmetric compact difference scheme is employed for the diffusive terms. The basic mean flow is obtained from the similarity solution of the compressible laminar boundary layer. In order to ensure the transition from the initial laminar flow to fully developed turbulence, a pair of oblique first-mode perturbation is imposed on the inflow boundary. The whole process of the spatial transition is obtained from the simulation. Through the space-time average, the variations of typical statistical quantities are analyzed. It is found that the distributions of turbulent Mach number, root-mean-square (rms fluctuation quantities, and Reynolds stresses along the wall-normal direction at different streamwise locations exhibit self-similarity in fully developed turbulent region. Finally, the onset and development of large-scale coherent structures through the transition process are depicted.

  15. Hydromagnetic natural convection flow between vertical parallel plates with time-periodic boundary conditions

    International Nuclear Information System (INIS)

    Adesanya, S.O.; Oluwadare, E.O.; Falade, J.A.; Makinde, O.D.

    2015-01-01

    In this paper, the free convective flow of magnetohydrodynamic fluid through a channel with time periodic boundary condition is investigated by taking the effects of Joule dissipation into consideration. Based on simplifying assumptions, the coupled governing equations are reduced to a set of nonlinear boundary valued problem. Approximate solutions are obtained by using semi-analytical Adomian decomposition method. The effect of pertinent parameters on the fluid velocity, temperature distribution, Nusselt number and skin friction are presented graphically and discussed. The result of the computation shows that an increase in the magnetic field intensity has significant influence on the fluid flow. - Highlights: • The influence of magnetic field on the free convective fluid flow is considered. • The coupled equations are solved by using Adomian decomposition method. • The Adomian series solution agreed with previously obtained result. • Magnetic field decreases the velocity maximum but enhances temperature field

  16. Offshore high - Boundaries: When 10 women jostle for personal space with 270 men, establishing limits is the key

    Energy Technology Data Exchange (ETDEWEB)

    Harvie, W.

    1998-06-01

    Male-female relationships on the Hibernia offshore site is discussed. Since women are outnumbered 27 to 1, some gender problems have been anticipated. Every employee on the platform, as well as every Hibernia and service company worker has taken gender sensitivity training and knows the rules. Although not every potential problem was anticipated, so far sexual harassment has not been a problem. The workers know what is acceptable and what is not, and the rules are generally observed. The ten women on the platform tend to work on administrative and support tasks, although by funding special scholarships the company is encouraging women to study engineering, computing and other petroleum-related fields, as well as pipefitting, welding and similar trades. The women aboard the platform live like the men, sharing a two-bunk berth with ensuite bathroom and shower. Off-duty time is spent congregating with the men in TV lounges, the smoking room or playing pool. Like the men, the women work 12-hour shifts for three weeks straight. It does get dull and repetitive, but in a province with chronic high unemployment, that is an acceptable irritation.

  17. Repeating Deep Very Low Frequency Earthquakes: An Evidence of Transition Zone between Brittle and Ductile Zone along Plate Boundary

    Science.gov (United States)

    Ishihara, Y.; Yamamoto, Y.; Arai, R.

    2017-12-01

    Recently slow or low frequency seismic and geodetic events are focused under recognition of important role in tectonic process. The most western region of Ryukyu trench, Yaeyama Islands, is very active area of these type events. It has semiannual-like slow slip (Heki et.al., 2008; Nishimura et.al.,2014) and very frequent shallow very low frequency earthquakes near trench zone (Ando et.al.,2012; Nakamura et.al.,2014). Arai et.al.(2016) identified clear reverse phase discontinuity along plate boundary by air-gun survey, suggesting existence of low velocity layer including fluid. The subducting fluid layer is considered to control slip characteristics. On the other hand, deep low frequency earthquake and tremor observed at south-western Honshu and Shikoku of Japan are not identified well due to lack of high-quality seismic network. A broadband seismic station(ISG/PS) of Pacific21 network is operating in last 20 years that locates on occurrence potential area of low frequency earthquake. We tried to review continuous broadband record, searching low frequency earthquakes. In pilot survey, we found three very low frequency seismic events which are dominant in less than 0.1Hz component and are not listed in earthquake catalogue. Source locates about 50km depth and at transition area between slow slip event and active area of general earthquake along plate boundary. To detect small and/or hidden very low frequency earthquake, we applied matched filter analysis to continuous three components waveform data using pre-reviewed seismogram as template signal. 12 events with high correlation are picked up in last 10 years. Most events have very similar waveform, which means characteristics of repeating deep very low frequency earthquake. The event history of very low frequency earthquake is not related with one of slow slip event in this region. In Yaeyama region, low frequency earthquake, general earthquake and slow slip event occur dividing in space and have apparent

  18. Laminar-Boundary-Layer Oscillations and Transition on a Flat Plate

    Science.gov (United States)

    1943-04-01

    ft) \\ axp <— b) Tha solution with the positiv « exponent must bo Ignored as it is Infinite at y • ». As the outor boundary con- dition, then, 0...34’.»*•* *’"**’ "• .F *- ^’•--i»-v 40 When quantitative work was attempted, It became ap- parent that the complicated sound field In the tunnel wae a decided...gradients decreased ampllfica damping) of .the oscillations while pos creased amplification. A quantitative this effect was therefore undertaken w

  19. Mixed convection boundary layer flow over a moving vertical flat plate in an external fluid flow with viscous dissipation effect.

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    Full Text Available The steady boundary layer flow of a viscous and incompressible fluid over a moving vertical flat plate in an external moving fluid with viscous dissipation is theoretically investigated. Using appropriate similarity variables, the governing system of partial differential equations is transformed into a system of ordinary (similarity differential equations, which is then solved numerically using a Maple software. Results for the skin friction or shear stress coefficient, local Nusselt number, velocity and temperature profiles are presented for different values of the governing parameters. It is found that the set of the similarity equations has unique solutions, dual solutions or no solutions, depending on the values of the mixed convection parameter, the velocity ratio parameter and the Eckert number. The Eckert number significantly affects the surface shear stress as well as the heat transfer rate at the surface.

  20. Development of Streamwise Counter-Rotating Vortices in Flat Plate Boundary Layer Pre-set by Leading Edge Patterns

    KAUST Repository

    Hasheminejad, S.M.

    2017-04-03

    Development of streamwise counter-rotating vortices induced by leading edge patterns with different pattern shape is investigated using hot-wire anemometry in the boundary layer of a flat plate. A triangular, sinusoidal and notched patterns with the same pattern wavelength λ of 15mm and the same pattern amplitude A of 7.5mm were examined for free-stream velocity of 3m/s. The results show a good agreement with earlier studies. The inflection point on the velocity profile downstream of the trough of the patterns at the beginning of the vortex formation indicates that the vortices non-linearly propagate downstream. An additional vortex structure was also observed between the troughs of the notched pattern.

  1. Fracture analysis of one-dimensional hexagonal quasicrystals: Researches of a finite dimension rectangular plate by boundary collocation method

    Energy Technology Data Exchange (ETDEWEB)

    Jiaxing, Cheng; Dongfa, Sheng [Southwest Forestry University, Yunnan (China)

    2017-05-15

    As an important supplement and development to crystallography, the applications about quasicrystal materials have played a core role in many fields, such as manufacturing and the space industry. Due to the sensitivity of quasicrystals to defects, the research on the fracture problem of quasicrystals has attracted a great deal of attention. We present a boundary collocation method to research fracture problems for a finite dimension rectangular one-dimensional hexagonal quasicrystal plate. Because mode I and mode II problems for one- dimensional hexagonal quasicrystals are like that for the classical elastic materials, only the anti-plane problem is discussed in this paper. The correctness of the present numerical method is verified through a comparison of the present results and the existing results. And then, the size effects on stress field, stress intensity factor and energy release rate are discussed in detail. The obtained results can provide valuable references for the fracture behavior of quasicrystals.

  2. Most-Critical Transient Disturbances in an Incompressible Flat-Plate Boundary Layer

    Science.gov (United States)

    Monschke, Jason; White, Edward

    2015-11-01

    Transient growth is a linear disturbance growth mechanism that plays a key role in roughness-induced boundary-layer transition. It occurs when superposed stable, non-orthogonal continuous spectrum modes experience algebraic disturbance growth followed by exponential decay. Algebraic disturbance growth can modify the basic state making it susceptible to secondary instabilities rapidly leading to transition. Optimal disturbance theory was developed to model the most-dangerous disturbances. However, evidence suggests roughness-induced transient growth is sub-optimal yet leads to transition earlier than optimal theory suggests. This research computes initial disturbances most unstable to secondary instabilities to further develop the applicability of transient growth theory to surface roughness. The main approach is using nonlinear adjoint optimization with solutions of the parabolized Navier-Stokes and BiGlobal stability equations. Two objective functions were considered: disturbance kinetic energy growth and sinuous instability growth rate. The first objective function was used as validation of the optimization method. Counter-rotating streamwise vortices located low in the boundary layer maximize the sinuous instability growth rate. The authors would like to acknowledge NASA and the AFOSR for funding this work through AFOSR Grant FA9550-09-1-0341.

  3. Wenlock-Ludlow boundary interval revisited: new insights from the offshore facies of the Prague Synform, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Štorch, Petr; Manda, Š.; Slavík, Ladislav; Tasáryová, Z.

    2016-01-01

    Roč. 53, č. 7 (2016), s. 666-673 ISSN 0008-4077. [Annual Meeting of the International-Geoscience-Programme (IGCP) Project 591 held jointly /5./ with the International Symposium on the Silurian System /5./. Quebec, 08.07.2016-11.07.2016] R&D Projects: GA ČR(CZ) GA14-16124S Institutional support: RVO:67985831 Keywords : graptolite * conodont * event * evolution * Bohemia * A-stable * bioturbation * boundary intervals * deep water * high resolution * organic-rich shales * stratigraphic intervals Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.923, year: 2016

  4. Numerical Investigation of Wall Cooling and Suction Effects on Supersonic Flat-Plate Boundary Layer Transition Using Large Eddy Simulation

    Directory of Open Access Journals (Sweden)

    Suozhu Wang

    2015-02-01

    Full Text Available Reducing friction resistance and aerodynamic heating has important engineering significance to improve the performances of super/hypersonic aircraft, so the purpose of transition control and turbulent drag reduction becomes one of the cutting edges in turbulence research. In order to investigate the influences of wall cooling and suction on the transition process and fully developed turbulence, the large eddy simulation of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 at different wall temperature and suction intensity is performed in the present work. It is found that the wall cooling and suction are capable of changing the mean velocity profile within the boundary layer and improving the stability of the flow field, thus delaying the onset of the spatial transition process. The transition control will become more effective as the wall temperature decreases, while there is an optimal wall suction intensity under the given conditions. Moreover, the development of large-scale coherent structures can be suppressed effectively via wall cooling, but wall suction has no influence.

  5. Analysis Of Convective Plane Stagnation Point Chemically Reactive Mhd Flow Past A Vertical Porous Plate With A Convective Boundary Condition In The Presence Of A Uniform Magnetic Field.

    OpenAIRE

    Adeniyan, A.,

    2013-01-01

    The numerical investigation of a stagnation point boundary layer flow , mass and heat transfer of a steady two dimensional , incompressible , viscous electrically conducting, chemically reacting laminar fluid over a vertical convectively heated , electrically neutral flat plate exposed to a transverse uniform magnetic field has been carried out to examine the influence of the simultaneous presence of the effects of a convective boundary condition, chemical reaction, heat transfer and suctio...

  6. Rapid Grain Size Reduction in the Upper Mantle at a Plate Boundary

    Science.gov (United States)

    Kidder, S. B.; Scott, J.; Prior, D. J.; Lubicich, E. J.

    2017-12-01

    process was very rapid (<10,000 yrs). In either case we interpret that semi-brittle deformation was a key process responsible for rapid localization in this initiating plate-scale mantle shear zone.

  7. Free vibration analysis of corroded steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Eslami-Majd, Alireza; Rahbar-Ranji, Ahmad [AmirKabir University of Technology, Tehran (Iran, Islamic Republic of)

    2014-06-15

    Vibration analysis of unstiffened/stiffened plates has long been studied due to its importance in the design and condition assessments of ship and offshore structures. Corrosion is inevitable in steel structures and has been so far considered in strength analysis of structures. We studied the free vibration of pitted corroded plates with simply supported boundary conditions. Finite element analysis, with ABAQUS, was used to determine the natural frequencies and mode shapes of corroded plates. Influential parameters including plate aspect ratio, degree of pit, one-sided/both-sided corroded plate, and different corrosion patterns were investigated. By increasing the degree of corrosion, reduction of natural frequency increases. Plate aspect ratio and plate dimensions have no influence on reduction of natural frequency. Different corrosion patterns on the surface of one-sided corroded plates have little influence on reduction of natural frequency. Ratio of pit depth over plate thickness has no influence on the reduction of natural frequency. The reduction of natural frequency in both-sided corroded plates is higher than one-sided corroded plates with the same amount of total corrosion loss. Mode shapes of vibration would change due to corrosion, except square mode shapes.

  8. Reconstructing Plate Boundaries in the Jurassic Neo-Tethys From the East and West Vardar Ophiolites (Greece and Serbia)

    Science.gov (United States)

    Maffione, Marco; van Hinsbergen, Douwe J. J.

    2018-03-01

    Jurassic subduction initiation in the Neo-Tethys Ocean eventually led to the collision of the Adria-Africa and Eurasia continents and the formation of an 6,000 km long Alpine orogen spanning from Iberia to Iran. Reconstructing the location and geometry of the plate boundaries of the now disappeared Neo-Tethys during the initial moments of its closure is instrumental to perform more realistic plate reconstructions of this region, of ancient ocean basins in general, and on the process of subduction initiation. Neo-Tethyan relics are preserved in an ophiolite belt distributed above the Dinaric-Hellenic fold-thrust belt. Here we provide the first quantitative constraints on the geometry of the spreading ridges and trenches active in the Jurassic Neo-Tethys using a paleomagnetically based net tectonic rotation analysis of sheeted dykes and dykes from the West and East Vardar Ophiolites of Serbia (Maljen and Ibar) and Greece (Othris, Pindos, Vourinos, and Guevgueli). Based on our results and existing geological evidence, we show that initial Middle Jurassic ( 175 Ma) closure of the western Neo-Tethys was accommodated at a N-S trending, west dipping subduction zone initiated near and parallel to the spreading ridge. The West Vardar Ophiolites formed in the forearc parallel to this new trench. Simultaneously, the East Vardar Ophiolites formed above a second N-S to NW-SE trending subduction zone located close to the European passive margin. We tentatively propose that this second subduction zone had been active since at least the Middle Triassic, simultaneously accommodating the closure of the Paleo-Tethys and the back-arc opening of Neo-Tethys.

  9. Frequency response of rectangular plates with free-edge openings and carlings subjected to point excitation force and enforced displacement at boundaries

    Directory of Open Access Journals (Sweden)

    Dae Seung Cho

    2016-03-01

    Full Text Available In this paper, a numerical procedure for the natural vibration analysis of plates with openings and carlings based on the assumed mode method is extended to assess their forced response. Firstly, natural response of plates with openings and carlings is calculated from the eigenvalue equation derived by using Lagrange's equation of motion. Secondly, the mode superposition method is applied to determine frequency response. Mindlin theory is adopted for plate modelling and the effect of openings is taken into account by subtracting their potential and kinetic energies from the corresponding plate energies. Natural and frequency response of plates with openings and carlings subjected to point excitation force and enforced acceleration at boundaries, respectively, is analysed by using developed in-house code. For the validation of the developed method and the code, extensive numerical results, related to plates with different opening shape, carlings and boundary conditions, are compared with numerical data from the relevant literature and with finite element solutions obtained by general finite element tool.

  10. Velocity- and slip-dependent weakening on the Tohoku plate boundary fault: shallow coseismic slip facilitated by foreshock afterslip

    Science.gov (United States)

    Ito, Y.; Ikari, M.; Ujiie, K.; Kopf, A.

    2016-12-01

    Understanding of role of slow earthquakes as they relate to the occurrence of both megathrust earthquakes and tsunami earthquakes is necessary to mitigate these disasters in the near future. Laboratory shearing experiments is one of important approach to evaluate these relationships. Here, we use powdered gouge samples from JFAST (IODP Expedition 343) Hole C0019E, core sample 17R-1, which is the plate boundary fault zone in the Japan Trench subduction zone. In this region, both large coseismic slip during the 2011 Tohoku-Oki earthquake as well as discrete slow slip events (SSE) have occurred. Experiments were conducted in a single-direct shear apparatus under normal stress of 16 MPa, with total shear displacements of up to 16 mm. We evaluate both the velocity- and slip-dependence of friction by extracting the velocity-dependent friction parameters a, b, and Dc, and measuring the rate of change in friction coefficient with shear displacement as the slip-dependence of friction. We report that in friction experiments using the Tohoku fault zone samples, an increase in sliding velocity exceeding that of earthquake afterslip can induce a change from steady-state frictional strength or slip hardening friction to slip-weakening frictional behavior. Our results show that the slip weakening is observed when the slip velocity exceeds 1 x 10-6 m/s during our experiments, while steady-state frictional strength or slip hardening is observed below 1x10-6 m/s. In the Japan Trench region, two slow events were observed at the downdip edge of the mainshock coseismic slip zone (< 30 m) were observed. These are an episodic SSE with a slip velocity of 0.1 x 10-6, and afterslip after the largest foreshock with a slip velocity of 2 x 10-6 m/s. This suggests that the afterslip may have facilitated the large coseismic slip during the mainshock on the plate boundary fault of the Tohoku-Oki earthquake.

  11. Dual Solutions in a Boundary Layer Flow of a Power Law Fluid over a Moving Permeable Flat Plate with Thermal Radiation, Viscous Dissipation and Heat Generation/Absorption

    Directory of Open Access Journals (Sweden)

    Aftab Ahmed

    2018-01-01

    Full Text Available The aim of the present study is to investigate the combined effects of the thermal radiation, viscous dissipation, suction/injection and internal heat generation/absorption on the boundary layer flow of a non-Newtonian power law fluid over a semi infinite permeable flat plate moving in parallel or reversely to a free stream. The resulting system of partial differential equations (PDEs is first transformed into a system of coupled nonlinear ordinary differential equations (ODEs which are then solved numerically by using the shooting technique. It is found that the dual solutions exist when the flat plate and the free stream move in the opposite directions. Dimensionless boundary layer velocity and temperature distributions are plotted and discussed for various values of the emerging physical parameters. Finally, the tables of the relevant boundary derivatives are presented for some values of the governing physical parameters.

  12. Lithospheric strength in the active boundary between the Pacific Plate and Baja California microplate constrained from lower crustal and upper mantle xenoliths

    Science.gov (United States)

    Chatzaras, Vasileios; van der Werf, Thomas; Kriegsman, Leo M.; Kronenberg, Andreas; Tikoff, Basil; Drury, Martyn R.

    2017-04-01

    The lower crust is the most poorly understood of the lithospheric layers in terms of its rheology, particularly at active plate boundaries. We studied naturally deformed lower crustal xenoliths within an active plate boundary, in order to link their microstructures and rheological parameters to the well-defined active tectonic context. The Baja California shear zone (BCSZ), located at the western boundary of the Baja California microplate, comprises the active boundary accommodating the relative motion between the Pacific plate and Baja California microplate. The basalts of the Holocene San Quintin volcanic field carry lower crustal and upper mantle xenoliths, which sample the Baja California microplate lithosphere in the vicinity of the BCSZ. The lower crustal xenoliths range from undeformed gabbros to granoblastic two-pyroxene granulites. Two-pyroxene geothermometry shows that the granulites equilibrated at temperatures of 690-920 oC. Phase equilibria (P-T pseudosections using Perple_X) indicate that symplectites with intergrown pyroxenes, plagioclase, olivine and spinel formed at 3.6-5.4 kbar, following decompression from pressures exceeding 6 kbar. FTIR spectroscopy shows that the water content of plagioclase varies among the analyzed xenoliths; plagioclase is relatively dry in two xenoliths while one xenolith contains hydrated plagioclase grains. Microstructural observations and analysis of the crystallographic texture provide evidence for deformation of plagioclase by a combination of dislocation creep and grain boundary sliding. To constrain the strength of the lower crust and upper mantle near the BCSZ we estimated the differential stress using plagioclase and olivine grain size paleopiezomtery, respectively. Differential stress estimates for plagioclase range from 10 to 32 MPa and for olivine are 30 MPa. Thus the active microplate boundary records elevated crustal temperatures, heterogeneous levels of hydration, and low strength in both the lower crust and

  13. An analysis of the relaxation of laminar boundary layer on a flat plate after passage of an interface with application to expansion-tube flows

    Science.gov (United States)

    Gupta, R. N.

    1972-01-01

    The relaxation of the accelerating-gas boundary layer to the test-gas boundary layer over a flat plate in an expansion tube is analyzed. Several combinations of test gas and acceleration gas are considered. The problem is treated in two conically similar limits: (1) when the time lag between the arrival of the shock and the interface at the leading edge of the plate is very large, and (2) when this lag is negligible. The time-dependent laminar-boundary-layer equations of a binary mixture of perfect gases are taken as the flow-governing equations. This coupled set of differential equations, written in terms of the Lam-Crocco variables, has been solved by a line-relaxation finite-difference techniques. The results presented include the Stanton number and the local skin-friction coefficient as functions of shock Mach number and the nondimensional distance-time variable. The results indicate that more than 95 percent of the test-gas boundary layer exists over a length, measured from the leading edge of the plate, equal to about three-tenths of the distance traversed by the interface in the free stream.

  14. An integral wall model for Large Eddy Simulation (iWMLES) and applications to developing boundary layers over smooth and rough plates

    Science.gov (United States)

    Yang, Xiang; Sadique, Jasim; Mittal, Rajat; Meneveau, Charles

    2014-11-01

    A new wall model for Large-Eddy-Simulations is proposed. It is based on an integral boundary layer method that assumes a functional form for the local mean velocity profile. The method, iWMLES, evaluates required unsteady and advective terms in the vertically integrated boundary layer equations analytically. The assumed profile contains a viscous or roughness sublayer, and a logarithmic layer with an additional linear term accounting for inertial and pressure gradient effects. The iWMLES method is tested in the context of a finite difference LES code. Test cases include developing turbulent boundary layers on a smooth flat plate at various Reynolds numbers, over flat plates with unresolved roughness, and a sample application to boundary layer flow over a plate that includes resolved roughness elements. The elements are truncated cones acting as idealized barnacle-like roughness elements that often occur in biofouling of marine surfaces. Comparisons with data show that iWMLES provides accurate predictions of near-wall velocity profiles in LES while, similarly to equilibrium wall models, its cost remains independent of Reynolds number and is thus significantly lower compared to standard zonal or hybrid wall models. This work is funded by ONR Grant N00014-12-1-0582 (Dr. R. Joslin, program manager).

  15. Heterogeneous distribution of pelagic sediments incoming the Japan Trench possibly controlling slip propagation on shallow plate boundary fault

    Science.gov (United States)

    Yamaguchi, A.; Nakamura, Y.; Fukuchi, R.; Kurano, H.; Ikehara, K.; Kanamatsu, T.; Arai, K.; Usami, K.; Ashi, J.

    2017-12-01

    Catastrophic tsunami of the 2011 Tohoku Earthquake was triggered by large coseismic slip reached to the Japan Trench axis (e.g. Fujiwara et al., 2011, Science; Kodaira et al., 2012, Nature Geoscience). Results of the IODP Expedition 343 (JFAST) suggest that small friction of smectite-rich pelagic clay caused slip propagation on shallow plate boundary fault (Ujiie et al., 2013, Science; Kameda et al., 2015, Geology; Moore et al., 2015, Geosphere). On the other hand, JAMSTEC high-resolution seismic profiles show that incoming sediments have large heterogeneities in thicknesses, and two areas of extremely thin sediments on the Pacific Plate (thickness less than 100 m) were found at around 39°N (Nakamura et al., AGU 2017, this session). To reconcile whether the smectite-rich pelagic clay even exists in these areas, we sampled surface sediments during the R/V Shinsei Maru KS-15-3 cruise. Seven piston cores were retrieved from seaward trench slope, horst, graben, and graben edge. Core lithologies are mainly diatomaceous ooze/clay including tephra layers, not resemble to pelagic clays discovered in JFAST. Ages of tephra layers were estimated by correlating mineral assemblages and refractive indices of volcanic glasses to Japanese widespread tephras. Averaged sedimentation rates of seaward trench slope, horst, graben, and graben edge are estimated to be 25-30, 6.5-20, 45, 0.9 cm/kyr, respectively. These sedimentation rates imply that sediments on seaward trench slope and horst have been deposited in the last 160-500 kyr, suggesting that entire pelagic sediments, including smectite-rich pelagic clay, have been removed by some reasons in the last 0.5 million years. Possible reason for such modification of sediment is near-trench igneous activity known as petit-spot volcanism (Hirano et al., 2006, Science). The lack of smectite-rich pelagic clay near 39°N of the Japan Trench is consistent with results of tsunami inversions proposing shallow large coseismic slip propagated

  16. Influence of electrical boundary conditions on profiles of acoustic field and electric potential of shear-horizontal acoustic waves in potassium niobate plates.

    Science.gov (United States)

    Kuznetsova, I E; Nedospasov, I A; Kolesov, V V; Qian, Z; Wang, B; Zhu, F

    2018-05-01

    The profiles of an acoustic field and electric potential of the forward and backward shear-horizontal (SH) acoustic waves of a higher order propagating in X-Y potassium niobate plate have been theoretically investigated. It has been shown that by changing electrical boundary conditions on a surface of piezoelectric plates, it is possible to change the distributions of an acoustic field and electric potential of the forward and backward acoustic waves. The dependencies of the distribution of a mechanical displacement and electrical potential over the plate thickness for electrically open and electrically shorted plates have been plotted. The influence of a layer with arbitrary conductivity placed on a one or on the both plate surfaces on the profiles under study, phase and group velocities of the forward and backward acoustic waves in X-Y potassium niobate has been also investigated. The obtained results can be useful for development of the method for control of a particle or electrical charge movement inside the piezoelectric plates, as well a sensor for definition of the thin film conductivity. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Thrust-wrench interference tectonics in the Gulf of Cadiz (Africa-Iberia plate boundary in the North-East Atlantic): Insights from analog models

    OpenAIRE

    Duarte , João ,; Rosas , Filipe ,; Terrinha , Pedro; Gutscher , Marc-André ,; Malavielle , Jacques; Silva , Sonia; Matias , Luis

    2011-01-01

    International audience; In the Gulf of Cadiz key segment of the Africa-Iberia plate boundary (North-East Atlantic ocean), three main different modes of tectonic interference between a recently identified wrench system (SWIM) and the Gulf of Cadiz Accretionary Wedge (GCAW) were tested through analog sand-box modeling: a) An active accretionary wedge on top of a pre-existent inactive basement fault; b) An active strike-slip fault cutting a previously formed, inactive, accretionary wedge; and c)...

  18. Spectral assessment of the turbulent convection velocity in a spatially developing flat plate turbulent boundary layer at Reynolds numbers up to Re θ = 13000

    OpenAIRE

    Renard , N.; Deck , S.; Sagaut , P.

    2014-01-01

    International audience; A method inspired by del Alamo et al. [1] is derived to assess the wavelength-dependent convection velocity in a zero pressure gradient spatially developing flat plate turbulent boundary layer at Retheta = 13 000 for all wavelengths and all wall distances, using only estimates of the time power spectral density of the streamwise velocity and of its local spatial derivative. The resulting global convection velocity has a least-squares interpretation and is easily relate...

  19. Vibration characteristics of functionally graded carbon nanotube reinforced composite rectangular plates on Pasternak foundation with arbitrary boundary conditions and internal line supports

    Science.gov (United States)

    Zhong, Rui; Wang, Qingshan; Tang, Jinyuan; Shuai, Cijun; Liang, Qian

    2018-02-01

    This paper presents the first known vibration characteristics of moderately thick functionally graded carbon nanotube reinforced composite rectangular plates on Pasternak foundation with arbitrary boundary conditions and internal line supports on the basis of the firstorder shear deformation theory. Different distributions of single walled carbon nanotubes (SWCNTs) along the thickness are considered. Uniform and other three kinds of functionally graded distributions of carbon nanotubes along the thickness direction of plates are studied. The solutions carried out using an enhanced Ritz method mainly include the following three points: Firstly, create the Lagrange energy function by the energy principle; Secondly, as the main innovation point, the modified Fourier series are chosen as the basic functions of the admissible functions of the plates to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges; Lastly, solve the natural frequencies as well as the associated mode shapes by means of the Ritz-variational energy method. In this study, the influences of the volume fraction of CNTs, distribution type of CNTs, boundary restrain parameters, location of the internal line supports, foundation coefficients on the natural frequencies and mode shapes of the FG-CNT reinforced composite rectangular plates are presented.

  20. 3D geometry of a plate boundary fault related to the 2016 Off-Mie earthquake in the Nankai subduction zone, Japan

    Science.gov (United States)

    Tsuji, Takeshi; Minato, Shohei; Kamei, Rie; Tsuru, Tetsuro; Kimura, Gaku

    2017-11-01

    We used recent seismic data and advanced techniques to investigate 3D fault geometry over the transition from the partially coupled to the fully coupled plate interface inboard of the Nankai Trough off the Kii Peninsula, Japan. We found that a gently dipping plate boundary décollement with a thick underthrust layer extends beneath the entire Kumano forearc basin. The 1 April 2016 Off-Mie earthquake (Mw6.0) and its aftershocks occurred, where the plate boundary décollement steps down close to the oceanic crust surface. This location also lies beneath the trenchward edge of an older accretionary prism (∼14 Ma) developed along the coast of the Kii peninsula. The strike of the 2016 rupture plane was similar to that of a formerly active splay fault system in the accretionary prism. Thus, the fault planes of the 2016 earthquake and its aftershocks were influenced by the geometry of the plate interface as well as splay faulting. The 2016 earthquake occurred within the rupture area of large interplate earthquakes such as the 1944 Tonankai earthquake (Mw8.1), although the 2016 rupture area was much smaller than that of the 1944 event. Whereas the hypocenter of the 2016 earthquake was around the underplating sequence beneath the younger accretionary prism (∼6 Ma), the 1944 great earthquake hypocenter was close to oceanic crust surface beneath the older accretionary prism. The variation of fault geometry and lithology may influence the degree of coupling along the plate interface, and such coupling variation could hinder slip propagation toward the deeper plate interface in the 2016 event.

  1. Using EarthScope Construction of the Plate Boundary Observatory to Provide Locally Based Experiential Education and Outreach

    Science.gov (United States)

    Jackson, M.; Eriksson, S.; Barbour, K.; Venator, S.; Mencin, D.; Prescott, W.

    2006-12-01

    EarthScope is an NSF-funded, national science initiative to explore the structure and evolution of the North American continent and to understand the physical processes controlling earthquakes and volcanoes. This large-scale experiment provides locally based opportunities for education and outreach which engage students at various levels and the public. UNAVCO is responsible for the Plate Boundary Observatory (PBO) component of EarthScope. PBO includes the installation and operations and maintenance of large networks of Global Positioning Satellite (GPS), strainmeter, seismometer, and tiltmeter instruments and the acquisition of satellite radar imagery, all of which will be used to measure and map the smallest movements across faults, the magma movement inside active volcanoes and the very wide areas of deformation associated with plate tectonic motion. UNAVCO, through its own education and outreach activities and in collaboration with the EarthScope E&O Program, uses the PBO construction activities to increase the understanding and public appreciation of geodynamics, earth deformation processes, and their relevance to society. These include programs for public outreach via various media, events associated with local installations, a program to employ students in the construction of PBO, and development of curricular materials by use in local schools associated with the EarthScope geographic areas of focus. PBO provides information to the media to serve the needs of various groups and localities, including interpretive centers at national parks and forests, such as Mt. St. Helens. UNAVCO staff contributed to a television special with the Spanish language network Univision Aquí y Ahora program focused on the San Andreas Fault and volcanoes in Alaska. PBO participated in an Education Day at the Pathfinder Ranch Science and Outdoor Education School in Mountain Center, California. Pathfinder Ranch hosts two of the eight EarthScope borehole strainmeters in the Anza

  2. Transformation of graphite by tectonic and hydrothermal processes in an active plate boundary fault zone, Alpine Fault, New Zealand

    Science.gov (United States)

    Kirilova, Matina; Toy, Virginia; Timms, Nicholas; Halfpenny, Angela; Menzies, Catriona; Craw, Dave; Rooney, Jeremy; Giorgetti, Carolina

    2017-04-01

    Graphite is a material with one of the lowest frictional strengths, with coefficient of friction of 0.1 and thus in natural fault zones it may act as a natural solid lubricant. Graphitization, or the transformation of organic matter (carbonaceous material, or CM) into crystalline graphite, is induced by compositional and structural changes during diagenesis and metamorphism. The supposed irreversible nature of this process has allowed the degree of graphite crystallinity to be calibrated as an indicator of the peak temperatures reached during progressive metamorphism. We examine processes of graphite emplacement and deformation in the Alpine Fault Zone, New Zealand's active continental tectonic plate boundary. Raman spectrometry indicates that graphite in the distal, amphibolite-facies Alpine Schist, which experienced peak metamorphic temperatures up to 640 ◦C, is highly crystalline and occurs mainly along grain boundaries within quartzo-feldspathic domains. The subsequent mylonitisation in the Alpine Fault Zone resulted in progressive reworking of CM under lower temperature conditions (500◦C-600◦C) in a structurally controlled environment, resulting in spatial clustering in lower-strain protomylonites, and further foliation-alignment in higher-strain mylonites. Subsequent brittle deformation of the mylonitised schists resulted in cataclasites that contain over three-fold increase in the abundance of graphite than mylonites. Furthermore, cataclasites contain graphite with two different habits: highly-crystalline, foliated forms that are inherited mylonitic graphite; and lower-crystallinity, less mature patches of finer-grained graphite. The observed graphite enrichment and the occurrence of poorly-organised graphite in the Alpine Fault cataclasites could result from: i) hydrothermal precipitation from carbon-supersaturated fluids; and/or ii) mechanical degradation by structural disordering of mylonitic graphite combined with strain-induced graphite

  3. Modeling the Geometry of Plate Boundary and Seismic Structure in the Southern Ryukyu Trench Subduction Zone, Japan, Using Amphibious Seismic Observations

    Science.gov (United States)

    Yamamoto, Y.; Takahashi, T.; Ishihara, Y.; Kaiho, Y.; Arai, R.; Obana, K.; Nakanishi, A.; Miura, S.; Kodaira, S.; Kaneda, Y.

    2018-02-01

    Here we present the new model, the geometry of the subducted Philippine Sea Plate interface beneath the southern Ryukyu Trench subduction zone, estimated from seismic tomography and focal mechanism estimation by using passive and active data from a temporary amphibious seismic network and permanent land stations. Using relocated low-angle thrust-type earthquakes, repeating earthquakes, and structural information, we constrained the geometry of plate boundary from the trench axis to a 60 km depth with uncertainties of less than 5 km. The estimated plate geometry model exhibited large variation, including a pronounced convex structure that may be evidence of a subducted seamount in the eastern portion of study area, whereas the western part appeared smooth. We also found that the active earthquake region near the plate boundary, defined by the distance from our plate geometry model, was clearly separated from the area dominated by short-term slow-slip events (SSEs). The oceanic crust just beneath the SSE-dominant region, the western part of the study area, showed high Vp/Vs ratios (>1.8), whereas the eastern side showed moderate or low Vp/Vs (<1.75). We interpreted this as an indication that high fluid pressures near the surface of the slab are contributing to the SSE activities. Within the toe of the mantle wedge, P and S wave velocities (<7.5 and <4.2 km/s, respectively) lower than those observed through normal mantle peridotite might suggest that some portions of the mantle may be at least 40% serpentinized.

  4. Transcending Borders and Traversing Boundaries: A Systematic Review of the Literature on Transnational, Offshore, Cross-Border, and Borderless Higher Education

    Science.gov (United States)

    Kosmützky, Anna; Putty, Rahul

    2016-01-01

    This article is a review of the literature concerned with transnational, offshore, cross-border, and borderless higher education, which together form a new thematic field within higher education research from the early 2000s onwards. The review places emphasis on the development of this field as well as its most cited contributions. The literature…

  5. MHD Heat and Mass Transfer of Chemical Reaction Fluid Flow over a Moving Vertical Plate in Presence of Heat Source with Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    B. R. Rout

    2013-01-01

    Full Text Available This paper aims to investigate the influence of chemical reaction and the combined effects of internal heat generation and a convective boundary condition on the laminar boundary layer MHD heat and mass transfer flow over a moving vertical flat plate. The lower surface of the plate is in contact with a hot fluid while the stream of cold fluid flows over the upper surface with heat source and chemical reaction. The basic equations governing the flow, heat transfer, and concentration are reduced to a set of ordinary differential equations by using appropriate transformation for variables and solved numerically by Runge-Kutta fourth-order integration scheme in association with shooting method. The effects of physical parameters on the velocity, temperature, and concentration profiles are illustrated graphically. A table recording the values of skin friction, heat transfer, and mass transfer at the plate is also presented. The discussion focuses on the physical interpretation of the results as well as their comparison with previous studies which shows good agreement as a special case of the problem.

  6. Offshoring Process

    DEFF Research Database (Denmark)

    Slepniov, Dmitrij; Sørensen, Brian Vejrum; Katayama, Hiroshi

    2011-01-01

    The purpose of this chapter is to contribute to the knowledge on how production offshoring and international operations management vary across cultural contexts. The chapter attempts to shed light on how companies approach the process of offshoring in different cultural contexts. In order...... of globalisation. Yet there are clear differences in how offshoring is conducted in Denmark and Japan. The main differences are outlined in a framework and explained employing cultural variables. The findings lead to a number of propositions suggesting that the process of offshoring is not simply a uniform...... technical-rational calculation of the most efficient organisation of activities across national borders, but it is rather specific to the parent companies’ national contexts....

  7. The effect of small streamwise velocity distortion on the boundary layer flow over a thin flat plate with application to boundary layer stability theory

    Science.gov (United States)

    Goldstein, M. E.; Leib, S. J.; Cowley, S. J.

    1990-01-01

    Researchers show how an initially linear spanwise disturbance in the free stream velocity field is amplified by leading edge bluntness effects and ultimately leads to a small amplitude but linear spanwise motion far downstream from the edge. This spanwise motion is imposed on the boundary layer flow and ultimately causes an order-one change in its profile shape. The modified profiles are highly unstable and can support Tollmein-Schlichting wave growth well upstream of the theoretical lower branch of the neutral stability curve for a Blasius boundary layer.

  8. 16 Years, 16 Cruises, 1.6 Billion Soundings: a Compilation of High-Resolution Multibeam Bathymetry of the Active Plate Boundary Along the Chilean Continental Margin

    Science.gov (United States)

    Weinrebe, W.; Flueh, E. R.; Hasert, M.; Behrmann, J. H.; Voelker, D.; Geersen, J.; Ranero, C. R.; Diaz-Naveas, J. L.

    2011-12-01

    Chile, a country stranding the active plate boundary between the South-American and the Nazca Plate is afflicted by recurrent earthquakes and hazardous volcanic eruptions. The strongest earthquake ever recorded occurred here, and volcanic hazards are frequent. Consequently, this area has been studied by geoscientists for many years to improve the understanding of subduction zone processes. Swath bathymetry mapping of the ocean floor has proven to bear a large potential for the interpretation of subduction-related processes, such as tectonic deformation of the marine forearc, release and migration of fluids as well as earthquake-triggered mass wasting. Multibeam bathymetry data of 16 major cruises of German, British, and Chilean research vessels recorded between 1995 and December 2010, in total more than 10,000 data files comprising about 1.6 billion soundings, have now been carefully reprocessed, compiled and merged into a unifying set of high-resolution bathymetric maps of the Chilean continental margin from latitude 40°S to 20°S. The imprint of subsurface processes on the surface morphology is well displayed in the case of the Chilean continental margin. The 3,500 km long Chilean convergent margin is not uniform, as various segments with different tectonic characteristics can be distinguished. Major factors that control margin morphology and thus the style of subduction are (1) relief and structure of the incoming oceanic plate, (2) supply of trench sediment, (3) turbidite transport within the trench, and (4) the input of terrigeneous sediments down the continental slope. A major segment boundary occurs at latitude 32°-33° S where the hotspot-related volcanic chain of Juan Fernandez is presently subducting. South of the area of ridge subduction the trench is filled with turbidites, and accretionary ridges develop across the base of the slope along most of the segment, whereas north of this boundary the turbiditic infill is reduced and subduction erosion is

  9. Comparison with Offshore and Onshore Mud Volcanoes in the Southwestern Taiwan

    Science.gov (United States)

    Chen, Y. H.; Su, C. C.; Chen, T. T.; Liu, C. S.; Paull, C. K.; Caress, D. W.; Gwiazda, R.; Lundsten, E. M.; Hsu, H. H.

    2017-12-01

    The offshore area southwest (SW) of Taiwan is on the convergent boundary between the Eurasian and Philippine Sea plates. The plate convergence manifests in this unique geological setting as a fold-and-thrust-belt. Multi-channel seismic profiles, and bathymetry and gravity anomaly data collected from Taiwan offshore to the SW show the presence of a large amount of mud volcanoes and diapirs with NE-SW orientations. In the absence of comprehensive sampling and detailed geochemistry data from submarine mud volcanoes, the relation between onshore and offshore mud volcanoes remains ambiguous. During two MBARI and IONTU joint cruises conducted in 2017 we collected high-resolution multibeam bathymetry data (1-m-resolution) and chirp sub-bottom profiles with an autonomous underwater vehicle (AUV) from submarine Mud Volcano III (MV3), and obtained precisely located samples and video observations with a remotely operated vehicle (ROV). MV3 is an active submarine mud volcano at 465 m water depth offshore SW Taiwan. This cone-shape mud volcano is almost 780 m wide, 150 m high, with 8° slopes, and a 30 m wide mound on the top. Several linear features are observed in the southwest of the mound, and these features are interpreted as a series of marks caused by rolling rocks that erupted from the top of MV3. We collected three rocks and push cores from MV3 and its top with the ROV, in order to compare their chemical and mineralogical composition to that of samples collected from mud volcanoes along the Chishan fault. The surface and X-radiography imaging, 210Pb chronology, grain size and X-ray diffractometer analyses were conducted to compare geochemical and sedimentary properties of offshore and onshore mud volcanoes. The results indicate that the offshore and onshore mud volcanoes have similar characteristics. We suggest that offshore and onshore mud volcanoes of SW Taiwan are no different in the source of their materials and their mechanism of creation and evolution.

  10. Influence of boundary conditions on the response of multilayered plates with cohesive interfaces and delaminations using a homogenized approach

    Directory of Open Access Journals (Sweden)

    R. Massabò

    2014-07-01

    Full Text Available Stress and displacement fields in multilayered composites with interfacial imperfections, such as imperfect bonding of the layers or delaminations, or where the plies are separated by thin interlayers allowing relative motion, have large variations in the thickness, with characteristic zigzag patterns and jumps at the layer interfaces. These effects are well captured by a model recently formulated by the author for multilayered plates with imperfect interfaces and affine interfacial traction laws (Massabò & Campi, Meccanica, 2014, in press; Compos Struct, 2014, 116, 311-324. The model defines a homogenized displacement field, which satisfies interfacial continuity, and uses a variational technique to derive equilibrium equations depending on only six generalized displacement functions, for any arbitrary numbers of layers and interfaces. The model accurately predicts stresses and displacements in simply supported, highly anisotropic, thick plates with continuous, sliding interfaces. In this paper the model is applied to wide plates with clamped edges and some inconsistencies, which have been noted in the literature for models based on similar approaches and have limited their utilization, are explained. A generalized transverse shear force is introduced as the gross stress resultant which is directly related to the bending moment in the equilibrium equations of multilayered structures with imperfect interfaces and substitutes for the shear force of single-layer theory. An application to a delaminated wide plate highlights the potential and limitations of the proposed model for the solution of fracture mechanics problems.

  11. The Ionian and Alfeo-Etna fault zones : New segments of an evolving plate boundary in the central Mediterranean Sea?

    NARCIS (Netherlands)

    Polonia, A.; Torelli, L.; Artoni, A.; Carlini, M.; Faccenna, C.; Ferranti, L.; Gasperini, L.; Govers, R.|info:eu-repo/dai/nl/108173836; Klaeschen, D.; Monaco, C.; Neri, G.; Nijholt, N.|info:eu-repo/dai/nl/413306674; Orecchio, B.; Wortel, R.|info:eu-repo/dai/nl/068439202

    2016-01-01

    The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the

  12. Impact of The N - S Fracture Zone Along The Indo-Australia Plate Analyzed from Local Seismic Data In The Western Offshore of Sumatra, Indonesia

    Science.gov (United States)

    Haridhi, H. A.; Klingelhoefer, F.; Huang, B. S.; Lee, C. S.

    2015-12-01

    Large subduction earthquake have repeatedly occurred along the Sumatra and Andaman subduction zones where the Indo-Australia plate is subducting beneath the Eurasian plate. We have analyzed earthquake data from local seismic network along the Sumatra region that provided by the Meteorology Climatology Geophysical Agencies of Indonesia (MCGAI), giving a reliable P-wave velocity model by using joint inversion of picked P-wave travel time using VELEST and a re-scanned single channel seismic reflection of Sumatra cruise I and II. As much as 1,503 events are being analyzed, that is from two years and three months of data recording (2009/04 - 2011/07). The VELEST and DD technique are used to relocate all events by forcing the obtained velocity model. It is found that the surface deformation and earthquake cluster are strongly influenced by the impact of an N - S subparalel fracture zone along the Indo-Australia plate. This also explains the seismic gaps along the Sumatra and Andaman subduction zones. So far, the intriguing seismogenic behaviour and forearc structure are not well explained by the existing models. Therefore, the planned IODP Expedition 362 is trying to ground truth the scientific questions. The aftershock earthquake data are huge, but they will provide a gateway to help the understanding of this shallow megathrust slip and reduce its devastated harzards.

  13. Offshore Outsourcing

    DEFF Research Database (Denmark)

    Petersen, Bent; Benito, Gabriel R. G.; Dovgan, Olesya

    While the extant literature on offshore outsourcing deals with this operation mode in isolation, and typically with a focus on cost effects, we address the broader question of how companies choose and use outsourcing as part of foreign operation mode development and as a contributor to internatio...... that outsourcing can be used proactively to promote expanded international operations.......While the extant literature on offshore outsourcing deals with this operation mode in isolation, and typically with a focus on cost effects, we address the broader question of how companies choose and use outsourcing as part of foreign operation mode development and as a contributor...

  14. HEAT AND MASS TRANSFER FOR VISCO-ELASTIC MHD BOUNDARY LAYER FLOW PAST A VERTICAL FLAT PLATE

    OpenAIRE

    Rita Choudhury; Hridi Ranjan Deb

    2012-01-01

    The two-dimensional free convection flow of visco-elastic and electrically conducting fluid past a vertical impermeable flat plate is considered in presence of a uniform transverse magnetic field. The governing equations are reduced to ordinary differential equation by introducing appropriate co-ordinate transformation. The analytical expressions for the velocity, temperature and species concentration fields have been obtained. The corresponding expressions for the non-dimensional rates of he...

  15. Active control of flow noise sources in turbulent boundary layer on a flat-plate using piezoelectric bimorph film

    International Nuclear Information System (INIS)

    Song, Woo Seog; Lee, Seung Bae; Shin, Dong Shin; Na, Yang

    2006-01-01

    The piezoelectric bimorph film, which, as an actuator, can generate more effective displacement than the usual PVDF film, is used to control the turbulent boundary-layer flow. The change of wall pressures inside the turbulent boundary layer is observed by using the multi-channel microphone array flush-mounted on the surface when actuation at the non-dimensional frequency f b + =0.008 and 0.028 is applied to the turbulent boundary layer. The wall pressure characteristics by the actuation to produce local displacement are more dominantly influenced by the size of the actuator module than the actuation frequency. The movement of large-scale turbulent structures to the upper layer is found to be the main mechanism of the reduction in the wall-pressure energy spectrum when the 700ν/u τ -long bimorph film is periodically actuated at the non-dimensional frequency f b + =0.008 and 0.028. The bimorph actuator is triggered with the time delay for the active forcing at a single frequency when a 1/8' pressure-type, pin-holed microphone sensor detects the large-amplitude pressure event by the turbulent spot. The wall-pressure energy in the late-transitional boundary layer is partially reduced near the convection wavenumber by the open-loop control based on the large amplitude event

  16. Focused Fluid Flow along Convergent Plate Boundaries - Deriving Flow Rates along Faults from Local Upwarping of the Base of the Gas Hydrate Stability Zone

    Science.gov (United States)

    Kunath, P.; Chi, W. C.; Liu, C. S.

    2017-12-01

    Convergent plate boundaries provide the ideal opportunity to examine the interactions of deformation, fluid flow and gas hydrate stability. However, there are still processes and parameters that remain unclear or scarce. This may be in part due to the fact that in situ determination of fluid flow rate is very difficult. Here, we present a newly developed 2-D hydrothermal model for (1) simulating the steady state, thermal effect of forced heat advection along a thin and shallow dipping fault and (2) quantifying fluid velocities required to deliver a thermal anomalies manifested at the bottom-simulating reflector (BSR) at its intersection with the fault zone. Assuming the horizontal thermal conduction is negligible, we derive our model using only a few crucial parameters: (a) the thermal conductivity structure between seafloor and fault; (b) the temperature at BSR depth and the seafloor; (c) fluid flow rate; (d) geometry of the fault conduit, including depth and thickness. Temperature disturbance is then described as a function of Peclet number and of the dip of the fault. Application of our model to Site 892 at Cascadia accretionary wedge (ODP Leg 146), where borehole data provide excellent thermal constraints on the hydrology, shows consistent results. By comparing the temperatures derived at the BSRs with the temperature field of our model, the results demonstrate that the temperature discrepancy is about 0 - 0.5 oC. We propose that this simple approach can provide, on the basis of a few parameters, rough estimate of the disturbance of the temperature caused by advecting fluid. Localized lateral BSR-based heat flow variations have been observed near thrust faults along many convergent plate boundaries around the world and are associated with strong localized fluid flow. We wish to further testing this approach using other seismic datasets to estimate first order of magnitude fluid migration patterns in other convergent boundaries.

  17. Changes in Student Knowledge and Views of Geohazards, Societal Risks, and Monitoring at Active Plate Boundaries Using a Data-Rich Curriculum

    Science.gov (United States)

    Selkin, P. A.; Goodell, L. P.; Teasdale, R.

    2015-12-01

    The "Living on the Edge: Building Resilient Societies on Active Plate Margins" curriculum consists of six data-rich activities, each intended for a 50-minute class, in which students assess risk at active plate boundaries due to earthquakes and volcanoes. Developed as part of the InTeGrate NSF STEP Center the peer-reviewed, publically available materials (http://serc.carleton.edu/104296) have been used at several institutions in diverse classroom settings including small laboratory sections, large lecture courses, medium-sized upper division courses and professional development programs for middle and high school teachers. Pre- and post-instruction surveys measured content knowledge and geoscience literacy, self-efficacy in using geologic data to assess hazards and risk, and attitudes towards the value of monitoring plate margins. The activities have overall positive effects on knowledge of geohazard concepts. Views about the value of scientific practice also became more positive: 74% of students indicated they "agree" or "strongly agree" that monitoring geologic activity has value to them personally (even if they don't live on an active plate margin) and 94% indicated that such monitoring is valuable to society. Most became more confident in evaluating geologic hazard and risk (>60% of students self-described increased confidence by one or more Likert levels). Student knowledge of both the types and limits of data in forecasting geological hazards and their effects also improved. However, attitudes toward sustainability and geoscience careers did not change. Learning and attitudinal improvements are true for all classroom types, but the degree of change varies with class size and the amount of time spent on activities. Learning data and instructor feedback suggest that interactive classroom activities that use real-world data to address societally relevant issues increase student learning and enhance students' ability to synthesize scientific information.

  18. Evolution of the Adria-Europe plate boundary in the northern Dinarides: From continent-continent collision to back-arc extension

    Science.gov (United States)

    Ustaszewski, Kamil; Kounov, Alexandre; Schmid, Stefan M.; Schaltegger, Urs; Krenn, Erwin; Frank, Wolfgang; Fügenschuh, Bernhard

    2010-12-01

    The Sava Zone of the northern Dinarides is part of the Cenozoic Adria-Europe plate boundary. Here Late Cretaceous subduction of remnants of Meliata-Vardar oceanic lithosphere led to the formation of a suture, across which upper plate European-derived units of Tisza-Dacia were juxtaposed with Adria-derived units of the Dinarides. Late Cretaceous siliciclastic sediments, deposited on the Adriatic plate, were incorporated into an accretionary wedge that evolved during the initial stages of continent-continent collision. Structurally deeper parts of the exposed accretionary wedge underwent amphibolite-grade metamorphism. Grt-Pl-Ms-Bt thermobarometry and multiphase equilibria indicate temperatures between 550°C and 630°C and pressures between 5 and 7 kbar for this event. Peak metamorphic conditions were reached at around 65 Ma. Relatively slow cooling from peak metamorphic conditions throughout most of the Paleogene was possibly induced by hanging wall erosion in conjunction with southwest directed propagation of thrusting in the Dinarides. Accelerated cooling took place in Miocene times, when the Sava Zone underwent substantial extension that led to the exhumation of the metamorphosed units along a low-angle detachment. Footwall exhumation started under greenschist facies conditions and was associated with top-to-the-north tectonic transport, indicating exhumation from below European plate units. Extension postdates the emplacement of a 27 Ma old granitoid that underwent solid-state deformation under greenschist facies conditions. The 40Ar/39Ar sericite and zircon and apatite fission track ages from the footwall allow bracketing this extensional unroofing between 25 and 14 Ma. This extension is hence linked to Miocene rift-related subsidence in the Pannonian basin, which represents a back-arc basin formed due to subduction rollback in the Carpathians.

  19. Application of the High Gradient hydrodynamics code to simulations of a two-dimensional zero-pressure-gradient turbulent boundary layer over a flat plate

    Science.gov (United States)

    Kaiser, Bryan E.; Poroseva, Svetlana V.; Canfield, Jesse M.; Sauer, Jeremy A.; Linn, Rodman R.

    2013-11-01

    The High Gradient hydrodynamics (HIGRAD) code is an atmospheric computational fluid dynamics code created by Los Alamos National Laboratory to accurately represent flows characterized by sharp gradients in velocity, concentration, and temperature. HIGRAD uses a fully compressible finite-volume formulation for explicit Large Eddy Simulation (LES) and features an advection scheme that is second-order accurate in time and space. In the current study, boundary conditions implemented in HIGRAD are varied to find those that better reproduce the reduced physics of a flat plate boundary layer to compare with complex physics of the atmospheric boundary layer. Numerical predictions are compared with available DNS, experimental, and LES data obtained by other researchers. High-order turbulence statistics are collected. The Reynolds number based on the free-stream velocity and the momentum thickness is 120 at the inflow and the Mach number for the flow is 0.2. Results are compared at Reynolds numbers of 670 and 1410. A part of the material is based upon work supported by NASA under award NNX12AJ61A and by the Junior Faculty UNM-LANL Collaborative Research Grant.

  20. Pleistocene slip rates on the Boconó fault along the North Andean Block plate boundary, Venezuela

    Science.gov (United States)

    Pousse-Beltran, Lea; Vassallo, Riccardo; Audemard, Franck; Jouanne, François; Carcaillet, Julien; Pathier, Erwan; Volat, Matthieu

    2017-07-01

    The Boconó fault is a strike-slip fault lying between the North Andean Block and the South American plate which has triggered at least five Mw > 7 historical earthquakes in Venezuela. The North Andean Block is currently moving toward NNE with respect to a stable South American plate. This relative displacement at 12 mm yr-1 in Venezuela (within the Maracaibo Block) was measured by geodesy, but until now the distribution and rates of Quaternary deformation have remained partially unclear. We used two alluvial fans offset by the Boconó fault (Yaracuy Valley) to quantify slip rates, by combining 10Be cosmogenic dating with measurements of tectonic displacements on high-resolution satellite images (Pleiades). Based upon a fan dated at >79 ka and offset by 1350-1580 m and a second fan dated at 120-273 ka and offset by 1236-1500 m, we obtained two Pleistocene rates of 5.0-11.2 and <20.0 mm yr-1, consistent with the regional geodesy. This indicates that the Boconó fault in the Yaracuy Valley accommodates 40 to 100% of the deformation between the South American plate and the Maracaibo Block. As no aseismic deformation was shown by interferometric synthetic aperture radar analysis, we assume that the fault is locked since the 1812 event. This implies that there is a slip deficit in the Yaracuy Valley since the last earthquake ranging from 1 to 4 m, corresponding to a Mw 7-7.6 earthquake. This magnitude is comparable to the 1812 earthquake and to other historical events along the Boconó fault.

  1. Application of He's homotopy perturbation method to boundary layer flow and convection heat transfer over a flat plate

    International Nuclear Information System (INIS)

    Esmaeilpour, M.; Ganji, D.D.

    2007-01-01

    In this Letter, the problem of forced convection over a horizontal flat plate is presented and the homotopy perturbation method (HPM) is employed to compute an approximation to the solution of the system of nonlinear differential equations governing on the problem. It has been attempted to show the capabilities and wide-range applications of the homotopy perturbation method in comparison with the previous ones in solving heat transfer problems. The obtained solutions, in comparison with the exact solutions admit a remarkable accuracy. A clear conclusion can be drawn from the numerical results that the HPM provides highly accurate numerical solutions for nonlinear differential equations

  2. Comparison of Different Analytic Solutions to Axisymmetric Squeezing Fluid Flow between Two Infinite Parallel Plates with Slip Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Hamid Khan

    2012-01-01

    Full Text Available We investigate squeezing flow between two large parallel plates by transforming the basic governing equations of the first grade fluid to an ordinary nonlinear differential equation using the stream functions ur(r,z,t=(1/r(∂ψ/∂z and uz(r,z,t=−(1/r(∂ψ/∂r and a transformation ψ(r,z=r2F(z. The velocity profiles are investigated through various analytical techniques like Adomian decomposition method, new iterative method, homotopy perturbation, optimal homotopy asymptotic method, and differential transform method.

  3. Transpressional Tectonics across the N. American-Caribbean Plate Boundary: Preliminary Results of a Multichannel Seismic Survey of Lake Azuei, Haiti.

    Science.gov (United States)

    Hearn, C. K.; Cormier, M. H.; Sloan, H.; Wattrus, N. J.; Boisson, D.; Brown, B.; Guerrier, K.; King, J. W.; Knotts, P.; Momplaisir, R.; Sorlien, C. C.; Stempel, R.; Symithe, S. J.; Ulysse, S. M. J.

    2017-12-01

    On January 12, 2010, a Mw 7.0 earthquake struck Haiti, killing over 200,000 people and devastating the Capital city of Port-au-Prince and the surrounding regions. It ruptured a previously unknown blind-thrust fault that abuts the Enriquillo Plantain Garden Fault (EPGF), one of two transform faults that define the North American-Caribbean plate boundary. That earthquake highlighted how transpression across this complex boundary is accommodated by slip partitioning into strike-slip and compressional structures. Because the seismic hazard is higher for a rupture on a reverse or oblique-slip fault than on a vertical strike-slip fault, the need to characterize the geometry of that fault system is clear. Lake Azuei overlies this plate boundary 60 km east of the 2010 epicenter. The lake's 23 km long axis trends NW-SE, parallel to the Haitian fold-and-thrust belt and oblique to the EPGF. This tectonic context makes it an ideal target for investigating the partitioning of plate motion between strike-slip and compressional structures. In January 2017, we acquired 222 km of multichannel seismic (MCS) profiles in the lake, largely concurrent with subbottom seismic (CHIRP) profiles. The MCS data were acquired using a high-frequency BubbleGun source and a 75 m-long, 24-channel streamer, achieving a 24 seismic fold with a penetration of 200 m below lakebed. With the goal of resolving tectonic structures in 3-D, survey lines were laid out in a grid with profiles spaced 1.2 km apart. Additional profiles were acquired at the SE end of the lake where most of the tectonic activity is presumably occurring. The co-located CHIRP and MCS profiles document the continuity of tectonic deformation between the surficial sediments and the deeper strata. Preliminary processing suggests that a SW-dipping blind thrust fault, expressed updip as a large monocline fold, may control the western edge of the lake. Gentle, young folds that protrude from the flat lakebed are also imaged with the CHIRP

  4. Plate boundary deformation in North Iceland during 1992–2009 revealed by InSAR time-series analysis and GPS

    KAUST Repository

    Metzger, Sabrina

    2014-08-20

    In North Iceland, extensional plate motion is accommodated by the Northern Volcanic Zone, a set of en-echelon volcanic systems, and the Tjörnes Fracture Zone, a transform offset in the mid-Atlantic Ridge consisting of two parallel transform lineaments. The southern lineament, the Húsavík–Flatey fault, is a 100 km-long right-lateral strike slip fault that has not ruptured for more than 140 years and poses a significant seismic hazard to Húsavík, a fishing town located by the fault, and to other coastal communities. We present results of InSAR time-series analysis data spanning almost two decades (1992–2009) that show extensional and interseismic deformation within the Northern Volcanic Zone and the on-shore part of the Tjörnes Fracture Zone. The results also exhibit transient inflation at Theistareykir volcano, deflation at Krafla central volcano and a broad uplift north of Krafla. The current plate extension is not uniform across the Northern Volcanic Zone, but concentrated at the western fissures of the Theistareykir volcanic system and the outermost fissures of the Krafla fissure swarm. We combine a back-slip plate boundary model with a set of point pressure sources representing volcanic changes to describe the current extensional plate boundary deformation and update the previous estimations of the locking depth and slip rate of the Húsavík–Flatey fault that were based on GPS data alone. Using different combinations of input data, we find that the Húsavík–Flatey fault has a locking depth of 6–10 km and, with a slip rate of 6–9 mm/yr, is accommodating about a third of the full transform motion. We furthermore show that while the InSAR data provide important constraints on the volcanic deformation within the NVZ, they do not significantly improve the model parameter estimation for the HFF, as the dense GPS network appears to better capture the deformation across the fault.

  5. Plate boundary deformation in North Iceland during 1992–2009 revealed by InSAR time-series analysis and GPS

    KAUST Repository

    Metzger, Sabrina; Jonsson, Sigurjon

    2014-01-01

    In North Iceland, extensional plate motion is accommodated by the Northern Volcanic Zone, a set of en-echelon volcanic systems, and the Tjörnes Fracture Zone, a transform offset in the mid-Atlantic Ridge consisting of two parallel transform lineaments. The southern lineament, the Húsavík–Flatey fault, is a 100 km-long right-lateral strike slip fault that has not ruptured for more than 140 years and poses a significant seismic hazard to Húsavík, a fishing town located by the fault, and to other coastal communities. We present results of InSAR time-series analysis data spanning almost two decades (1992–2009) that show extensional and interseismic deformation within the Northern Volcanic Zone and the on-shore part of the Tjörnes Fracture Zone. The results also exhibit transient inflation at Theistareykir volcano, deflation at Krafla central volcano and a broad uplift north of Krafla. The current plate extension is not uniform across the Northern Volcanic Zone, but concentrated at the western fissures of the Theistareykir volcanic system and the outermost fissures of the Krafla fissure swarm. We combine a back-slip plate boundary model with a set of point pressure sources representing volcanic changes to describe the current extensional plate boundary deformation and update the previous estimations of the locking depth and slip rate of the Húsavík–Flatey fault that were based on GPS data alone. Using different combinations of input data, we find that the Húsavík–Flatey fault has a locking depth of 6–10 km and, with a slip rate of 6–9 mm/yr, is accommodating about a third of the full transform motion. We furthermore show that while the InSAR data provide important constraints on the volcanic deformation within the NVZ, they do not significantly improve the model parameter estimation for the HFF, as the dense GPS network appears to better capture the deformation across the fault.

  6. The Effect of Heat Transfer on MHD Marangoni Boundary Layer Flow Past a Flat Plate in Nanofluid

    Directory of Open Access Journals (Sweden)

    D. R. V. S. R. K. Sastry

    2013-01-01

    Full Text Available The problem of heat transfer on the Marangoni convection boundary layer flow in an electrically conducting nanofluid is studied. Similarity transformations are used to transform the set of governing partial differential equations of the flow into a set of nonlinear ordinary differential equations. Numerical solutions of the similarity equations are then solved through the MATLAB “bvp4c” function. Different nanoparticles like Cu, Al2O3, and TiO2 are taken into consideration with water as base fluid. The velocity and temperature profiles are shown in graphs. Also the effects of the Prandtl number and solid volume fraction on heat transfer are discussed.

  7. Influence of yield stress on free convective boundary-layer flow of a non-Newtonian nanofluid past a vertical plate in a porous medium

    International Nuclear Information System (INIS)

    Hady, F. M.; Ibrahim, F. S.; Abdel-Gaied, S. M.; Eid, M. R.

    2011-01-01

    The effect of yield stress on the free convective heat transfer of dilute liquid suspensions of nanofluids flowing on a vertical plate saturated in porous medium under laminar conditions is investigated considering the nanofluid obeys the mathematical model of power-law. The model used for non-Newtonian nanofluid incorporates the effects of Brownian motion and thermophoresis. The governing boundary- layer equations are cast into dimensionless system which is solved numerically using a deferred correction technique and Newton iteration. This solution depends on yield stress parameter Ω, a power-law index n, Lewis number Le, a buoyancy-ratio number Nr, a Brownian motion number Nb, and a thermophoresis number Nt. Analyses of the results found that the reduced Nusselt and Sherwood numbers are decreasing functions of the higher yield stress parameter for each dimensionless numbers, n and Le, except the reduced Sherwood number is an increasing function of higher Nb for different values of yield stress parameter

  8. The M w = 5.8 14 August 2016 middle Sakhalin earthquake on a boundary between Okhotsk and Eurasian (Amurian) plates

    Science.gov (United States)

    Konovalov, A. V.; Stepnov, A. A.; Safonov, D. A.; Kozhurin, A. I.; Pavlov, A. S.; Gavrilov, A. V.; Manaychev, K. A.; Tomilev, D. Ye.; Takahashi, H.; Ichiyanagi, M.

    2018-04-01

    An earthquake with the moment magnitude M w = 5.8 occurred in the middle part of the Sakhalin Island, Russian Federation, on 14 August 2016, at 11:17 a.m. UTC. The earthquake source was located west of the Central Sakhalin Fault Zone, which is considered to mark the boundary between the Okhotsk and Eurasian (Amurian) plates. Moment tensor solution of the mainshock as well as the configuration of aftershock cloud suggests that the earthquake was caused by slip on a SW-dipping reverse fault. For the first time for Sakhalin, we have got the felt reports unified in accordance with DYFI. We also analyzed observed PGA values and, based on them, produced shaking maps.

  9. Free convection boundary layer flow past a horizontal flat plate embedded in porous medium filled by nano-fluid containing gyro-tactic microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, A. [Department of Mechanical Engineering, School of Engineering and Applied Science, Gonzaga University, Spokane, WA 99258 (United States); Khan, W.A. [Department of Engineering Sciences, National University of Sciences and Technology, Karachi 75350 (Pakistan); Pop, I. [Department of Applied Mathematics, Babes-Bolyai University, Cluj-Napoca (Romania)

    2012-06-15

    The steady boundary layer free convection flow past a horizontal flat plate embedded in a porous medium filled by a water-based nano-fluid containing gyro-tactic microorganisms is investigated. The Oberbeck-Boussinesq approximation is assumed in the analysis. The effects of bio-convection parameters on the dimensionless velocity, temperature, nano-particle concentration and density of motile microorganisms as well as on the local Nusselt, Sherwood and motile microorganism numbers are investigated and presented graphically. In the absence of bio-convection, the results are compared with the existing data in the open literature and found to be in good agreement. The bio-convection parameters strongly influence the heat, mass, and motile microorganism transport rates. (authors)

  10. Some Exact Solutions of Boundary Layer Flows along a Vertical Plate with Buoyancy Forces Combined with Lorentz Forces under Uniform Suction

    Directory of Open Access Journals (Sweden)

    Asterios Pantokratoras

    2008-01-01

    Full Text Available Exact analytical solutions of boundary layer flows along a vertical porous plate with uniform suction are derived and presented in this paper. The solutions concern the Blasius, Sakiadis, and Blasius-Sakiadis flows with buoyancy forces combined with either MHD Lorentz or EMHD Lorentz forces. In addition, some exact solutions are presented specifically for water in the temperature range of 0∘C≤≤8∘C, where water density is nearly parabolic. Except for their use as benchmarking means for testing the numerical solution of the Navier-Stokes equations, the presented exact solutions with EMHD forces have use in flow separation control in aeronautics and hydronautics, whereas the MHD results have applications in process metallurgy and fusion technology. These analytical solutions are valid for flows with strong suction.

  11. Accessing offshoring advantages

    DEFF Research Database (Denmark)

    Mykhaylenko, Alona; Motika, Agnes; Wæhrens, Brian Vejrum

    2015-01-01

    . Assuming that different levels of synergy may exist between particular offshoring strategic decisions (choosing offshore outsourcing or captive offshoring and the type of function) and different offshoring advantages, this work advocates that the actual fact of realization of certain offshoring advantages...

  12. Active tectonic deformation of the western Indian plate boundary: A case study from the Chaman Fault System

    Science.gov (United States)

    Crupa, Wanda E.; Khan, Shuhab D.; Huang, Jingqiu; Khan, Abdul S.; Kasi, Aimal

    2017-10-01

    Collision of the Eurasian and Indian plates has resulted in two spatially offset subduction zones, the Makran subduction zone to the south and the Himalayan convergent margin to the north. These zones are linked by a system of left-lateral strike-slip faults known as the Chaman Fault System, ∼1200 km, which spans along western Pakistan. Although this is one of the greatest strike-slip faults, yet temporal and spatial variation in displacement has not been adequately defined along this fault system. This study conducted geomorphic and geodetic investigations along the Chaman Fault in a search for evidence of spatial variations in motion. Four study areas were selected over the span of the Chaman Fault: (1) Tarnak-Rud area over the Tarnak-Rud valley, (2) Spinatizha area over the Spinatizha Mountain Range, (3) Nushki area over the Nushki basin, and (4) Kharan area over the northern tip of the Central Makran Mountains. Remote sensing data allowed for in depth mapping of different components and faults within the Kohjak group. Wind and water gap pairs along with offset rivers were identified using high-resolution imagery and digital-elevation models to show displacement for the four study areas. The mountain-front-sinuosity ratio, valley height-to-width-ratio, and the stream-length-gradient index were calculated and used to determine the relative tectonic activity of each area. These geomorphic indices suggest that the Kharan area is the most active and the Tarnak-Rud area is the least active. GPS data were processed into a stable Indian plate reference frame and analyzed. Fault parallel velocity versus fault normal distance yielded a ∼8-10 mm/yr displacement rate along the Chaman Fault just north of the Spinatizha area. InSAR data were also integrated to assess displacement rates along the fault system. Geodetic data support that ultra-slow earthquakes similar to those that strike along other major strike-slip faults, such as the San Andreas Fault System, are

  13. Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

    Science.gov (United States)

    van der Werf, Thomas; Chatzaras, Vasileios; Marcel Kriegsman, Leo; Kronenberg, Andreas; Tikoff, Basil; Drury, Martyn R.

    2017-12-01

    The rheology of lower crust and its transient behavior in active strike-slip plate boundaries remain poorly understood. To address this issue, we analyzed a suite of granulite and lherzolite xenoliths from the upper Pleistocene-Holocene San Quintín volcanic field of northern Baja California, Mexico. The San Quintín volcanic field is located 20 km east of the Baja California shear zone, which accommodates the relative movement between the Pacific plate and Baja California microplate. The development of a strong foliation in both the mafic granulites and lherzolites, suggests that a lithospheric-scale shear zone exists beneath the San Quintín volcanic field. Combining microstructural observations, geothermometry, and phase equilibria modeling, we estimated that crystal-plastic deformation took place at temperatures of 750-890 °C and pressures of 400-560 MPa, corresponding to 15-22 km depth. A hot crustal geotherm of 40 ° C km-1 is required to explain the estimated deformation conditions. Infrared spectroscopy shows that plagioclase in the mafic granulites is relatively dry. Microstructures are interpreted to show that deformation in both the uppermost lower crust and upper mantle was accommodated by a combination of dislocation creep and grain-size-sensitive creep. Recrystallized grain size paleopiezometry yields low differential stresses of 12-33 and 17 MPa for plagioclase and olivine, respectively. The lower range of stresses (12-17 MPa) in the mafic granulite and lherzolite xenoliths is interpreted to be associated with transient deformation under decreasing stress conditions, following an event of stress increase. Using flow laws for dry plagioclase, we estimated a low viscosity of 1.1-1.3×1020 Pa ṡ s for the high temperature conditions (890 °C) in the lower crust. Significantly lower viscosities in the range of 1016-1019 Pa ṡ s, were estimated using flow laws for wet plagioclase. The shallow upper mantle has a low viscosity of 5.7×1019 Pa ṡ s

  14. High-Resolution P'P' Precursor Imaging of Nazca-South America Plate Boundary Zones and Inferences for Transition Zone Temperature and Composition

    Science.gov (United States)

    Gu, Y. J.; Schultz, R.

    2013-12-01

    Knowledge of upper mantle transition zone stratification and composition is highly dependent on our ability to efficiently extract and properly interpret small seismic arrivals. A promising high-frequency seismic phase group particularly suitable for a global analysis is P'P' precursors, which are capable of resolving mantle structures at vertical and lateral resolution of approximately 5 and 200 km, respectively, owing to their shallow incidence angle and small, quasi-symmetric Fresnel zones. This study presents a simultaneous analysis of SS and P'P' precursors based on deconvolution, Radon transform and depth migration. Our multi-resolution survey of the mantle near Nazca-South America subduction zone reveals both olivine and garnet related transitions at depth below 400 km. We attribute a depressed 660 to thermal variations, whereas compositional variations atop the upper-mantle transition zone are needed to explain the diminished or highly complex reflected/scattered signals from the 410 km discontinuity. We also observe prominent P'P' reflections within the transition zone, especially near the plate boundary zone where anomalously high reflection amplitudes result from a sharp (~10 km thick) mineral phase change resonant with the dominant frequency of the P'P' precursors. Near the base of the upper mantle, the migration of SS precursors shows no evidence of split reflections near the 660-km discontinuity, but potential majorite-ilmenite (590-640 km) and ilmenite-perovskite transitions (740-750 km) are identified based on similarly processed high-frequency P'P' precursors. At nominal mantle temperatures these two phase changes may be seismically indistinguishable, but colder mantle conditions from the descending Nazca plate, the presence of water and variable Fe contents may cause sufficient separation for a reliable analysis. In addition, our preliminary results provide compelling evidence for multiple shallow lower-mantle reflections (at ~800 km) along the

  15. Deep seismic transect across the Tonankai earthquake area obtained from the onshore- offshore wide-angle seismic study

    Science.gov (United States)

    Nakanishi, A.; Obana, K.; Kodaira, S.; Miura, S.; Fujie, G.; Ito, A.; Sato, T.; Park, J.; Kaneda, Y.; Ito, K.; Iwasaki, T.

    2008-12-01

    In the Nankai Trough subduction seismogenic zone, M8-class great earthquake area can be divided into three segments; they are source regions of the Nankai, Tonankai and presumed Tokai earthquakes. The Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. Hypocenters of these great earthquakes were usually located off the cape Shiono, Kii Peninsula, and the rupture propagated westwards and eastwards, respectively. To obtain the deep structure of the down-dip limit of around the Nankai Trough seismogenic zone, the segment boundary and first break area off the Kii Peninsula, the onshore-offshore wide-angle seismic studies was conducted in the western and eastern part of the Kii Peninsula and their offshore area in 2004 and 2006, respectively. The result of the seismic study in 2004 is mainly shown here. Structural images along the onshore and offshore profiles have already been separately obtained. In this study, an onshore-offshore integrated image of the western part of the Kii Peninsula, ~400km in a total length, is obtained from first arrival tomography and traveltime mapping of reflection phases by combining dataset of 13 land explosions, 2269 land stations, 36 OBSs and 1806 offshore airgun shots. The subduction angle of the Philippine Sea plate (PSP) gradually increases landward up to ~20-25 degree. Beneath the onshore part, the subducting PSP is estimated at ~5km shallower than that previously derived from seismicity. Low frequency earthquakes (identified and picked by Japan Meteorological Agency) are relocated around the plate interface of the subducting PSP by using the deep seismic transect obtained in this study. The offshore research is part of 'Structure research on plate dynamics of the presumed rupture zone of the Tonankai-Nankai Earthquakes' funded by Ministry of Education, Culture, Sports, Science and Technology (MEXT). The onshore research carried by the Kyoto University is part of 'Special Project for

  16. New methods to cope with temperature elevations in heated segments of flat plates cooled by boundary layer flow

    Directory of Open Access Journals (Sweden)

    Hajmohammadi Mohammad R.

    2016-01-01

    Full Text Available This paper documents two reliable methods to cope with the rising temperature in an array of heated segments with a known overall heat load and exposed to forced convective boundary layer flow. Minimization of the hot spots (peak temperatures in the array of heated segments constitutes the primary goal that sets the platform to develop the methods. The two proposed methods consist of: 1 Designing an array of unequal heaters so that each heater has a different size and generates heat at different rates, and 2 Distancing the unequal heaters from each other using an insulated spacing. Multi-scale design based on constructal theory is applied to estimate the optimal insulated spacing, heaters size and heat generation rates, such that the minimum hot spots temperature is achieved when subject to space constraint and fixed overall heat load. It is demonstrated that the two methods can considerably reduce the hot spot temperatures and consequently, both can be utilized with confidence in industry to achieve optimized heat transfer.

  17. Slip-dependent weakening on shallow plate boundary fault in the Japan subduction zone: shallow coseismic slip facilitated by foreshock afterslip

    Science.gov (United States)

    Ito, Yoshi; Ikari, Matt; Ujiie, Kohtaro; Kopf, Achim

    2017-04-01

    Understanding of role of slow earthquakes as they relate to the occurrence of both megathrust earthquakes and tsunami earthquakes is necessary to mitigate these disasters in the near future. Laboratory shearing experiments is one of important approach to evaluate these relationships. Here, we use powdered gouge samples from JFAST (IODP Expedition 343) Hole C0019E, core sample 17R-1, which is the plate boundary fault zone in the Japan Trench subduction zone. In this region, both large coseismic slip during the 2011 Tohoku-Oki earthquake as well as discrete slow slip events (SSE) have occurred. Experiments were conducted in a single-direct shear apparatus under normal stress of 16 MPa, with total shear displacements of up to 16 mm. We evaluate the slip-dependence of friction by extracting the velocity-dependent friction parameters a, b, and Dc , and also measure the rate of change in friction coefficient with shear displacement as the slip-dependence of friction. We report that in friction experiments using the Tohoku fault zone samples, an increase in sliding velocity exceeding that of earthquake afterslip can induce a change from steady-state frictional strength or slip hardening friction to slip-weakening frictional behavior. Our results show that the slip weakening is observed when the slip velocity exceeds 3.7 × 10-6 m/s during our experiments, while steady-state frictional strength or slip hardening is observed below 1 × 10-6 m/s. In the Japan Trench region, two slow events prior to the mainshock were observed in the mainshock area with a coseismic slip exceeding 30 m . One event is an episodic SSE with a slip velocity of 0.1 × 10-6 , and the other is afterslip after the largest Tohoku earthquake foreshock with a slip velocity exceeding 2 × 10-6 m/s. Our experiments show that slip-weakening friction should be expected at the afterslip rate, suggesting that the afterslip may have facilitated the large coseismic slip during the mainshock on the plate boundary

  18. The Sorong Fault Zone, Indonesia: Mapping a Fault Zone Offshore

    Science.gov (United States)

    Melia, S.; Hall, R.

    2017-12-01

    The Sorong Fault Zone is a left-lateral strike-slip fault zone in eastern Indonesia, extending westwards from the Bird's Head peninsula of West Papua towards Sulawesi. It is the result of interactions between the Pacific, Caroline, Philippine Sea, and Australian Plates and much of it is offshore. Previous research on the fault zone has been limited by the low resolution of available data offshore, leading to debates over the extent, location, and timing of movements, and the tectonic evolution of eastern Indonesia. Different studies have shown it north of the Sula Islands, truncated south of Halmahera, continuing to Sulawesi, or splaying into a horsetail fan of smaller faults. Recently acquired high resolution multibeam bathymetry of the seafloor (with a resolution of 15-25 meters), and 2D seismic lines, provide the opportunity to trace the fault offshore. The position of different strands can be identified. On land, SRTM topography shows that in the northern Bird's Head the fault zone is characterised by closely spaced E-W trending faults. NW of the Bird's Head offshore there is a fold and thrust belt which terminates some strands. To the west of the Bird's Head offshore the fault zone diverges into multiple strands trending ENE-WSW. Regions of Riedel shearing are evident west of the Bird's Head, indicating sinistral strike-slip motion. Further west, the ENE-WSW trending faults turn to an E-W trend and there are at least three fault zones situated immediately south of Halmahera, north of the Sula Islands, and between the islands of Sanana and Mangole where the fault system terminates in horsetail strands. South of the Sula islands some former normal faults at the continent-ocean boundary with the North Banda Sea are being reactivated as strike-slip faults. The fault zone does not currently reach Sulawesi. The new fault map differs from previous interpretations concerning the location, age and significance of different parts of the Sorong Fault Zone. Kinematic

  19. Prediction of an internal boundary layer on a flat plate after a step change in roughness using a near-wall RANS model

    Science.gov (United States)

    Chu, Minghan; Meng, Fanxiao; Bergstrom, Donald J.

    2017-11-01

    An in-house computational fluid dynamics code was used to simulate turbulent flow over a flat plate with a step change in roughness, exhibiting a smooth-rough-smooth configuration. An internal boundary layer (IBL) is formed at the transition from the smooth to rough (SR) and then the rough to smooth (RS) surfaces. For an IBL the flow far above the surface has experienced a wall shear stress that is different from the local value. Within a Reynolds-Averaged-Navier-Stokes (RANS) formulation, the two-layer k- ɛ model of Durbin et al. (2001) was implemented to analyze the response of the flow to the change in surface condition. The numerical results are compared to experimental data, including some in-house measurements and the seminal work of Antonia and Luxton (1971,72). This problem captures some aspects of roughness in industrial and environmental applications, such as corrosion and the earth's surface heterogeneity, where the roughness is often encountered as discrete distributions. It illustrates the challenge of incorporating roughness models in RANS that are capable of responding to complex surface roughness profiles.

  20. A new algorithm for three-dimensional joint inversion of body wave and surface wave data and its application to the Southern California plate boundary region

    Science.gov (United States)

    Fang, Hongjian; Zhang, Haijiang; Yao, Huajian; Allam, Amir; Zigone, Dimitri; Ben-Zion, Yehuda; Thurber, Clifford; van der Hilst, Robert D.

    2016-05-01

    We introduce a new algorithm for joint inversion of body wave and surface wave data to get better 3-D P wave (Vp) and S wave (Vs) velocity models by taking advantage of the complementary strengths of each data set. Our joint inversion algorithm uses a one-step inversion of surface wave traveltime measurements at different periods for 3-D Vs and Vp models without constructing the intermediate phase or group velocity maps. This allows a more straightforward modeling of surface wave traveltime data with the body wave arrival times. We take into consideration the sensitivity of surface wave data with respect to Vp in addition to its large sensitivity to Vs, which means both models are constrained by two different data types. The method is applied to determine 3-D crustal Vp and Vs models using body wave and Rayleigh wave data in the Southern California plate boundary region, which has previously been studied with both double-difference tomography method using body wave arrival times and ambient noise tomography method with Rayleigh and Love wave group velocity dispersion measurements. Our approach creates self-consistent and unique models with no prominent gaps, with Rayleigh wave data resolving shallow and large-scale features and body wave data constraining relatively deeper structures where their ray coverage is good. The velocity model from the joint inversion is consistent with local geological structures and produces better fits to observed seismic waveforms than the current Southern California Earthquake Center (SCEC) model.

  1. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    process constrain the seismic hazard assessment. Some frequent issues .... to obtain information on the causality between .... 2004), and low frequency deep triggering. (Miyazawa .... can trigger shallow thrust fault earthquakes; Science 306.

  2. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    time series to determine the causality and related orientation. The resulting link ... Triggering causes changes in the Coulomb stress on a specified fault, which is ... work link shows that the alignment of the links is parallel to the Honshu Trench ...

  3. Late Quaternary uplift along the North America-Caribbean plate boundary: Evidence from the sea level record of Guantanamo Bay, Cuba

    Science.gov (United States)

    Muhs, Daniel R.; Schweig, Eugene S.; Simmons, Kathleen R.; Halley, Robert B.

    2017-12-01

    The tectonic setting of the North America-Caribbean plate boundary has been studied intensively, but some aspects are still poorly understood, particularly along the Oriente fault zone. Guantanamo Bay, southern Cuba, is considered to be on a coastline that is under a transpressive tectonic regime along this zone, and is hypothesized to have a low uplift rate. We tested this by studying emergent reef terrace deposits around the bay. Reef elevations in the protected, inner part of the bay are ∼11-12 m and outer-coast, wave-cut benches are as high as ∼14 m. Uranium-series analyses of corals yield ages ranging from ∼133 ka to ∼119 ka, correlating this reef to the peak of the last interglacial period, marine isotope stage (MIS) 5.5. Assuming a span of possible paleo-sea levels at the time of the last interglacial period yields long-term tectonic uplift rates of 0.02-0.11 m/ka, supporting the hypothesis that the tectonic uplift rate is low. Nevertheless, on the eastern and southern coasts of Cuba, east and west of Guantanamo Bay, there are flights of multiple marine terraces, at higher elevations, that could record a higher rate of uplift, implying that Guantanamo Bay may be anomalous. Southern Cuba is considered to have experienced a measurable but modest effect from glacial isostatic adjustment (GIA) processes. Thus, with a low uplift rate, Guantanamo Bay should show no evidence of emergent marine terraces dating to the ∼100 ka (MIS 5.3) or ∼80 ka (MIS 5.1) sea stands and results of the present study support this.

  4. Structural and Tectonic Map Along the Pacific-North America Plate Boundary in Northern Gulf of California, Sonora Desert and Valle de Mexicali, Mexico, from Seismic Reflection Evidence

    Science.gov (United States)

    Gonzalez-Escobar, M.; Suarez-Vidal, F.; Mendoza-Borunda, R.; Martin Barajas, A.; Pacheco-Romero, M.; Arregui-Estrada, S.; Gallardo-Mata, C.; Sanchez-Garcia, C.; Chanes-Martinez, J.

    2012-12-01

    Between 1978 and 1983, Petróleos Mexicanos (PEMEX) carried on an intense exploration program in the northern Gulf of California, the Sonora Desert and the southern part of the Mexicali Valley. This program was supported by a seismic reflection field operation. The collected seismic data was 2D, with travel time of 6 s recording, in 48 channels, and the source energy was: dynamite, vibroseis and air guns. Since 2007 to present time, the existing seismic data has been re-processing and ire-interpreting as part of a collaboration project between the PEMEX's Subdirección de Exploración (PEMEX) and CICESE. The study area is located along a large portion of the Pacific-North America plate boundary in the northern Gulf of California and the Southern part of the Salton Trough tectonic province (Mexicali Valley). We present the result of the processes reflection seismic lines. Many of the previous reported known faults were identify along with the first time described located within the study region. We identified regions with different degree of tectonic activity. In structural map it can see the location of many of these known active faults and their associated seismic activity, as well as other structures with no associated seismicity. Where some faults are mist placed they were deleted or relocated based on new information. We included historical seismicity for the region. We present six reflection lines that cross the aftershocks zone of the El Mayor-Cucapah earthquake of April 4, 2010 (Mw7.2). The epicenter of this earthquake and most of the aftershocks are located in a region where pervious to this earthquake no major earthquakes are been reported. A major result of this study is to demonstrate that there are many buried faults that increase the seismic hazard.

  5. Geometry of the Arabia-Somalia Plate Boundary into Afar: Preliminary Results from the Seismic Profile Across the Asal Rift (Djibouti)

    Science.gov (United States)

    Vergne, J.; Doubre, C.; Mohamed, K.; Tiberi, C.; Leroy, S.; Maggi, A.

    2010-12-01

    In the Afar Depression, the Asal-Ghoubbet Rift in Djibouti is a young segment on land at the propagating tip of the Aden Ridge. This segment represents an ideal laboratory to observe the mechanisms of extension and the structural evolutions involved, from the continental break-up to the first stage of oceanic spreading. However, we lack first order information about the crustal and upper mantle structure in this region, which for example prevent detailed numerical modeling of the deformations observed at the surface from GPS or InSAR. Moreover the current permanent network is not well suited to precisely constrain the ratio of seismic/aseismic deformation and to characterize the active deformation and the rifting dynamics. Since November 2009 we have maintained a temporary network of 25 seismic stations deployed along a 150 km-long profile. Because we expect rapid variations of the lithospheric structure across the 10 km-wide central part of the rift, we gradually decreased the inter-stations spacing to less than 1 km in the middle section of the profile. In order to obtain a continuous image of the plate boundary, from the topographic surface to the upper mantle, several techniques and methods will be applied: P and S wave receiver functions, tomographies based on body waves, surface waves and seismic noise correlation, anisotropy, and finally a gravity-seismic joint inversion. We present some preliminary results deduced from the receiver functions applied to the data acquired during the first months of the experiment. We migrate several sets of receiver functions computed in various frequency bands to resolve both mantle interfaces and fine scale structures within the thin crust in the center of the rift. These first images confirm a rapid variation of the Moho depth on both sides of the rift and a very complex lithospheric structure in the central section with several low velocity zones within the top 50km that might correspond to magma lenses.

  6. Impacts of variable thermal conductivity on stagnation point boundary layer flow past a Riga plate with variable thickness using generalized Fourier's law

    Science.gov (United States)

    Shah, S.; Hussain, S.; Sagheer, M.

    2018-06-01

    This article explores the problem of two-dimensional, laminar, steady and boundary layer stagnation point slip flow over a Riga plate. The incompressible upper-convected Maxwell fluid has been considered as a rheological fluid model. The heat transfer characteristics are investigated with generalized Fourier's law. The fluid thermal conductivity is assumed to be temperature dependent in this study. A system of partial differential equations governing the flow of an upper-convected Maxwell fluid, heat and mass transfer using generalized Fourier's law is developed. The main objective of the article is to inspect the impacts of pertinent physical parameters such as the stretching ratio parameter (0 ⩽ A ⩽ 0.3) , Deborah number (0 ⩽ β ⩽ 0.6) , thermal relaxation parameter (0 ⩽ γ ⩽ 0.5) , wall thickness parameter (0.1 ⩽ α ⩽ 3.5) , slip parameter (0 ⩽ R ⩽ 1.5) , thermal conductivity parameter (0.1 ⩽ δ ⩽ 1.0) and modified Hartmann number (0 ⩽ Q ⩽ 3) on the velocity and temperature profiles. Suitable local similarity transformations have been used to get a system of non-linear ODEs from the governing PDEs. The numerical solutions for the dimensionless velocity and temperature distributions have been achieved by employing an effective numerical method called the shooting method. It is seen that the velocity profile shows the reduction in the velocity for the higher values of viscoelastic parameter and the thermal relaxation parameter. In addition, to enhance the reliability at the maximum level of the obtained numerical results by shooting method, a MATLAB built-in solver bvp4c has also been utilized.

  7. Offshore wind energy developments

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Buhl, Thomas; Sumer, B. Mutlu

    2014-01-01

    This chapter will give a brief overview of a few of the activities within offshore wind energy research, specifically 1) Support structure optimization, 2) Blade coatings for wind turbines; 3) Scour protection of foundations, 4) Offshore HVDC and 5) Offshore wind services....

  8. Offshoring and International Competitiveness

    DEFF Research Database (Denmark)

    Ørberg Jensen, Peter D.; Pedersen, Torben

    2012-01-01

    During the past decade, offshoring has become an established business practice. Yet it is still more common to offshore less advanced tasks compared with offshoring more advanced tasks, i.e., tasks closer to the core activities of the firm. The latter is a new phenomenon which raises many new iss...

  9. GPS Installation Progress in the Northern California Region of the Plate Boundary Observatory Coyle, B., Basset, A., Williams, T., Enders, M., Feaux, K., Jackson, M.

    Science.gov (United States)

    Coyle, B.; Basset, A.; Enders, M.; Williams, T.; Feaux, K.; Jackson, M.

    2005-12-01

    The Plate Boundary Observatory (PBO) is the geodetic component of the NSF funded EarthScope Project . The final PBO GPS network will comprise 875 continuously operating GPS stations installed throughout the Western US and Alaska. There are 435 stations planned for California with 229 of these in Northern California (NCA). This poster will present the past year's progress of GPS installations in NCA. At the end of the first year of the Project, PBO NCA installed 12 stations. During the second year, another 56 were installed for a total of 68 stations including 18 SDBM, and 50 DDBM. We have sited 128 stations, submitted 112 permit applications and received 73 permits. A particularly important statistic for planning our schedules is the time lag between reconnaissance and permit accepted; our average thus far is 137 days. We have been particularly successful locating stations on Caltrans Rights of Way with 20 Stations built, 3 sites permitted and 5 permits pending. Other land use partners include: East Bay Regional Parks - 8 Stations built and 2 sites permitted, Bureau of Land Management - 5 Stations built, 3 permits pending, Water Municipalities - 4 Stations built, 3 sites permitted and 4 permits pending, and Airports - 4 Stations built and 3 permits pending. Highlights from last year: On September 28, 2004 a Mw 6.0 earthquake occurred on the San Andreas Fault seven miles southeast of the town of Parkfield, CA. Field crews from the Northern and Southern California offices of PBO began the site reconnaissance and permitting process the day after the earthquake and installation of the first Station was begun within 36 hours and completed the following day. In total, 5 Stations were installed by the first week of November. On June 14, 2045 a Mw 7.1 earthquake occurred on the Gorda Plate, approximately 100 miles NW of Eureka. PBO stations, P158, P162, P169 and P170, recorded coseismic deformation associated with this event. We plan to have 127 stations built by the end

  10. Negotiating and Spanning Boundaries in Offshore Outsourcing

    DEFF Research Database (Denmark)

    Sonne, Tine; Søderberg, Anne-Marie; Tøth, Thomas

    2013-01-01

    intercultural collaboration with managers and staff at the outsourcing client´s site. We also raise the question: Who and what motivates them to stay at work in this Indian IT development context where many Western clients have experienced serious challenges with outsourcing due to high attrition rates...

  11. From Offshoring to Backshoring

    DEFF Research Database (Denmark)

    Slepniov, Dmitrij; Madsen, Erik Skov

    2015-01-01

    The purpose of this paper is to examine the evolution of offshoring over time. The paper employs qualitative methodology and on the basis of two case studies of Danish companies, it develops a framework conceptualizing the stages of offshoring and highlights the factors driving the transition...... between these stages. The framework challenges the linear nature of offshoring and proposes the existence of ‘the pendulum effect’. The pendulum effect suggests that the modes of offshoring (i.e. captive and non-captive) and geographies of offshoring (i.e. home and abroad) are not static; rather...

  12. Bending and stretching of plates

    CERN Document Server

    Mansfield, E H; Hemp, W S

    1964-01-01

    The Bending and Stretching of Plates deals with elastic plate theory, particularly on small- and large-deflexion theory. Small-deflexion theory concerns derivation of basic equations, rectangular plates, plates of various shapes, plates whose boundaries are amenable to conformal transformation, plates with variable rigidity, and approximate methods. Large-deflexion theory includes general equations and some exact solutions, approximate methods in large-deflexion theory, asymptotic large-deflexion theories for very thin plates. Asymptotic theories covers membrane theory, tension field theory, a

  13. How Long Is Long Enough? Estimation of Slip-Rate and Earthquake Recurrence Interval on a Simple Plate-Boundary Fault Using 3D Paleoseismic Trenching

    Science.gov (United States)

    Wechsler, N.; Rockwell, T. K.; Klinger, Y.; Agnon, A.; Marco, S.

    2012-12-01

    Models used to forecast future seismicity make fundamental assumptions about the behavior of faults and fault systems in the long term, but in many cases this long-term behavior is assumed using short-term and perhaps non-representative observations. The question arises - how long of a record is long enough to represent actual fault behavior, both in terms of recurrence of earthquakes and of moment release (aka slip-rate). We test earthquake recurrence and slip models via high-resolution three-dimensional trenching of the Beteiha (Bet-Zayda) site on the Dead Sea Transform (DST) in northern Israel. We extend the earthquake history of this simple plate boundary fault to establish slip rate for the past 3-4kyr, to determine the amount of slip per event and to study the fundamental behavior, thereby testing competing rupture models (characteristic, slip-patch, slip-loading, and Gutenberg Richter type distribution). To this end we opened more than 900m of trenches, mapped 8 buried channels and dated more than 80 radiocarbon samples. By mapping buried channels, offset by the DST on both sides of the fault, we obtained for each an estimate of displacement. Coupled with fault crossing trenches to determine event history, we construct earthquake and slip history for the fault for the past 2kyr. We observe evidence for a total of 9-10 surface-rupturing earthquakes with varying offset amounts. 6-7 events occurred in the 1st millennium, compared to just 2-3 in the 2nd millennium CE. From our observations it is clear that the fault is not behaving in a periodic fashion. A 4kyr old buried channel yields a slip rate of 3.5-4mm/yr, consistent with GPS rates for this segment. Yet in spite of the apparent agreement between GPS, Pleistocene to present slip rate, and the lifetime rate of the DST, the past 800-1000 year period appears deficit in strain release. Thus, in terms of moment release, most of the fault has remained locked and is accumulating elastic strain. In contrast, the

  14. Floating Foundations for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Andersen, Morten Thøtt

    The concept of harnessing the power of the wind dates all the way back to the first ships traversing the seas. Later, windmills enabled the use of wind power for industrial purposes. Since then, technology has allowed the production of clean renewable energy through the use of wind turbines....... These turbines have traditionally been placed on land, but several factors have urged a move to offshore locations. Now the boundaries are being pushed into deeper and deeper waters, where the idea of floating offshore wind turbines has emerged. In less than a decade, these have gone from scattered small...

  15. Panorama 2012 - Offshore hydrocarbons

    International Nuclear Information System (INIS)

    Serbutoviez, Sylvain

    2011-12-01

    Technological progress is enabling production from offshore oil and gas fields at increasingly ambitious depths (3, 000 metres). Investment in offshore production is running at around $100 billion per year, accounting for one-fifth of all investment in oil exploration and development worldwide. However, the global economic crisis that broke at the end of 2008 and the accident involving the Macondo well temporarily disrupted the race to deep offshore technology. (author)

  16. Offshore Transmission Technology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-10-15

    The purpose of this document is to give an overview of offshore electricity transmission technologies. In particular this document is concerned with the use of High Voltage Direct Current (HVDC) systems and more specifically with the development of Voltage Source Converter (VSC) technology. This report outlines the current state of the main technology groups required for offshore HVDC transmission as well as giving examples of offshore projects (both current and future). Finally some indications of likely unit costs for HV assets are given.

  17. Occupational health offshore

    Energy Technology Data Exchange (ETDEWEB)

    Crosbie, A.; Davies, F.

    2002-07-01

    The proceedings contain the 29 papers presented at the conference plus the opening address from the chair of the Health and Safety Commission. The papers in the first session were concerned with policy, strategy and leadership and included a perspective from the offshore industry advisory committee, details of a health planning tool for occupational health assurance and lessons from occupational health management in the offshore sector. The two sessions on the second day dealt with occupational health in the offshore design process and case studies involving physical, chemical and biological agents. Topics included the need to consider occupational health when designing offshore installations, the development of a human factors engineering strategy in petrochemical engineering projects, measuring occupational exposure to hazardous chemicals, implementation of the noise at work regulations, hand arm vibration syndrome and issues with potable water maintenance. The two sessions on the third day were concerned with human factors and psychological health, and well-being and fitness for duty. Topics covered included circadian adaption to shift change in offshore shift workers, managing stress in the offshore environment, the role of employee assistance programmes in organisational stress management, health care and first aid (the revised ACOP), well-being at work, the medical and physical fitness of offshore emergency response rescue team members, the impact of health surveillance and promotion of offshore accident rates, and the implication of safety and heath of the aging of the workforce ion the Norwegian offshore industry.

  18. Similarity Solution for Combined Free-Forced Convection Past a Vertical Porous Plate in a Porous Medium with a Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    Garg P.

    2016-12-01

    Full Text Available This paper studies the mathematical implications of the two dimensional viscous steady laminar combined free-forced convective flow of an incompressible fluid over a semi infinite fixed vertical porous plate embedded in a porous medium. It is assumed that the left surface of the plate is heated by convection from a hot fluid which is at a temperature higher than the temperature of the fluid on the right surface of the vertical plate. To achieve numerical consistency for the problem under consideration, the governing non linear partial differential equations are first transformed into a system of ordinary differential equations using a similarity variable and then solved numerically under conditions admitting similarity solutions. The effects of the physical parameters of both the incompressible fluid and the vertical plate on the dimensionless velocity and temperature profiles are studied and analysed and the results are depicted both graphically and in a tabular form. Finally, algebraic expressions and the numerical values are obtained for the local skin-friction coefficient and the local Nusselt number.

  19. Offshoring research directions

    NARCIS (Netherlands)

    Velthuijsen, Hugo

    2012-01-01

    Outsourcing and offshoring provide companies with ways to achieve their business objectives better or more cost effectively or despite a shortage of specific resources. From a research point of view, outsourcing and offshoring have mostly been studied as something that large companies do, not small

  20. Organizational Adaptation in Offshoring

    DEFF Research Database (Denmark)

    Geisler Asmussen, Christian; Møller Larsen, Marcus; Pedersen, Torben

    2016-01-01

    Offshoring offers managers the promise of substantial economic benefits, but also comes with the risk of increased complexity and coordination challenges. We argue that offshoring firms must accumulate architectural knowledge to keep the cost of coordination of the geographically separated activi...

  1. Offshore Investment Funds

    Directory of Open Access Journals (Sweden)

    Shang-Jin Wei

    1999-12-01

    Full Text Available Offshore investment funds are alleged to have engaged in trading behavior that is different from their onshore counterparts because they may be subject to less supervision and regulation. In particular, they may trade more intensely. They could also pursue more aggressively certain trading strategies such as positive feedback trading or herding that could contribute to a greater volatility in the market. Using a unique data set, this chapter compares the trading behavior in the Korean stock market between offshore investment funds with their onshore counterparts registered in the US and UK. There are a number of interesting findings. First, there is indeed evidence suggesting that the offshore funds trade more intensely than their onshore counterparts. Second, however, there is no evidence that the offshore funds engage in positive feedback trading. In contrast, there is strong evidence that the funds from the U.S. and U.K. do. Third, while offshore funds do herd, they do so far less than onshore funds in the U.S. or UK. Fourth, offshore funds hold less glamour stocks (e.g. stocks with high P/E in their portfolio than funds in the U.S. or U.K. do. Moreover, flight to glamour stocks during the in-crisis period is less evident in the case of offshore funds. In sum, offshore funds are no especially worrisome monsters.

  2. Offshore wind development research.

    Science.gov (United States)

    2014-04-01

    Offshore wind (OSW) development is a new undertaking in the US. This project is a response to : New Jerseys 2011 Energy Master Plan that envisions procuring 22.5% of the states power : originating from renewable sources by 2021. The Offshore Wi...

  3. Global offshore pipeline markets

    International Nuclear Information System (INIS)

    Knight, R.; Parsons, B.

    2001-01-01

    In this article, two experts forecast a recovery in the offshore pipeline market followed by accelerating growth. A number of clearly definable macro trends are affecting the world offshore oil and gas industry and will be of considerable significance to the offshore pipelines industry. The authors' view is of markets that show every chance of enjoying long-term growth prospects driven by the fundamentals of a continuing increase in demand for offshore oil and gas. The offshore industry however has a highly cyclical nature, due to the impact of variations in oil and gas prices and the differing state of maturity of individual regions. Therefore those companies that are able to offer the widest range of pipe types and diameters and methods of installation across the greatest range of geographic markets are likely to prosper most. Thus, this continues to be a market best suited to those able to operate on a global scale and make a corporate commitment measured in decades

  4. Offshore risk assessment

    CERN Document Server

    Vinnem, Jan-Erik

    2014-01-01

      Offshore Risk Assessment was the first book to deal with quantified risk assessment (QRA) as applied specifically to offshore installations and operations. Risk assessment techniques have been used for more than three decades in the offshore oil and gas industry, and their use is set to expand increasingly as the industry moves into new areas and faces new challenges in older regions.   This updated and expanded third edition has been informed by a major R&D program on offshore risk assessment in Norway and summarizes research from 2006 to the present day. Rooted with a thorough discussion of risk metrics and risk analysis methodology,  subsequent chapters are devoted to analytical approaches to escalation, escape, evacuation and rescue analysis of safety and emergency systems.   Separate chapters analyze the main hazards of offshore structures: fire, explosion, collision, and falling objects as well as structural and marine hazards. Risk mitigation and control are discussed, as well as an illustrat...

  5. Comment on “A similarity solution for laminar thermal boundary layer over a flat plate with a convective surface boundary condition” by A. Aziz, Comm. Nonlinear Sci. Numer. Simul. 2009;14:1064-8

    Science.gov (United States)

    Magyari, Eugen

    2011-01-01

    In a recent paper published in this Journal the title problem has been investigated numerically. In the present paper the exact solution for the temperature boundary layer is given in terms of the solution of the flow problem (the Blasius problem) in a compact integral form.

  6. Assessing offshore wind potential

    International Nuclear Information System (INIS)

    Adelaja, Adesoji; McKeown, Charles; Calnin, Benjamin; Hailu, Yohannes

    2012-01-01

    Quantifying wind potential is a pivotal initial step in developing and articulating a state’s policies and strategies for offshore wind industry development. This is particularly important in the Great Lakes States where lessons from other offshore environments are not directly applicable. This paper presents the framework developed for conducting a preliminary assessment of offshore wind potential. Information on lake bathymetry and wind resources were combined in simulating alternative scenarios of technically feasible turbine construction depths and distance concerns by stakeholders. These yielded estimates of developable offshore wind areas and potential power generation. While concerns about the visibility of turbines from shore reduce the power that can be generated, engineering solutions that increase the depths at which turbines can be sited increase such potential power output. This paper discusses the costs associated with technical limitations on depth and the social costs related to public sentiments about distance from the shoreline, as well as the possible tradeoffs. The results point to a very large untapped energy resource in the Michigan’s Great Lakes, large enough to prompt policy action from the state government. - Highlights: ▶ We build a theoretical framework for modeling offshore wind power production. ▶ Illustration of the impact of technology and social limitations on offshore wind energy development. ▶ Geospatial modeling of the offshore wind potential of the Great Lakes.

  7. Offshore wind energy prospects

    International Nuclear Information System (INIS)

    Gaudiosi, Gaetano

    1999-01-01

    In last two years offshore wind energy is becoming a focal point of national and non national organisations particularly after the limitations of fossil fuel consumption, adopted by many developed countries after Kyoto conference at the end of 1997 on global climate change. North Europe is particularly interested in offshore for the limited land areas still available, due to the intensive use of its territory and its today high wind capacity. Really the total wind capacity in Europe could increase from the 1997 value of 4450 MW up to 40 000 MW within 2010, according the White Paper 1997 of the European Commission; a significant percentage (25%) could be sited offshore up to 10 000 MW, because of close saturation of the land sites at that time. World wind capacity could increase from the 1997 value of 7200 MW up to 60 000 MW within 2010 with a good percentage (20%) offshore 12 000 MW. In last seven years wind capacity in shallow water of coastal areas has reached 34 MW. Five wind farms are functioning in the internal seas of Netherlands, Denmark, Sweden; however such siting is mostly to be considered as semi-offshore condition. Wind farms in real offshore sites, open seas with waves and water depth over 10 m, are now proposed in North Sea at 10-20 km off the coasts of Netherlands, Denmark using large size wind turbine (1-2 MW). In 1997 an offshore proposal was supported in Netherlands by Greenpeace after the OWEMES '97 seminar, held in Italy on offshore wind in the spring 1997. A review is presented in the paper of European offshore wind programs with trends in technology, economics and siting effects. (Author)

  8. Import, Offshoring and Wages

    DEFF Research Database (Denmark)

    Fosse, Henrik Barslund; Maitra, Madhura

    Offshoring firms are found to pay higher average wages than purely domestic firms. We provide a unifying empirical approach by capturing the different channels through which offshoring may explain this wage difference: (i) due to change in the composition of workers (skill composition effect) (ii......) because all existing workers get higher pay (rent sharing effect). Using Danish worker-firm data we explain how much each channel contributes to higher wages. To estimate the causal effect of offshoring on wages we use China’s accession to the WTO in December 2001 - and the soon after boom in Chinese...

  9. The Fairway-Aotea Basin and the New Caledonia Trough, witnesses of the Pacific-Australian plate boundary evolution : from mid-Cretaceous cessation of subduction to Eocene subduction renewal

    Science.gov (United States)

    Collot, J.; Geli, L. B.; Lafoy, Y.; Sutherland, R.; Herzer, R. H.; Roest, W. R.

    2009-12-01

    The geodynamical history of the SW Pacific is controlled since the Mesozoic by the evolution of peri-Pacific subduction zones, in a trench retreat by slab roll-back process, which successively occurred along the Eastern Gondwana margin. In this context, most basins which formed after 45 Ma reached a stage of seafloor spreading, have recorded the inversions of the earth's magnetic field and present typical oceanic crust morphologies. By contrast, the New Caledonia and Fairway basins, which are narrower and present thick sedimentary covers have a less known and more controversial origin. Based on a regional geological synthesis and on interpretation of multichannel seismic reflection and refraction data, combined with drill hole data off New Zealand and a compilation of regional potential data, we distinguish 2 phases of the evolution of the Fairway-Aotea Basin (FAB) and the New Caledonia Trough (NCT), which reflect the evolution of the Gondwana-Pacific plate boundary: Phase 1: Mid Cretaceous formation of the FAB in a continental intra- or back- arc position of the Pacific-Gondwana subduction system. The formation of this shallow basin reflects the onset of continental breakup of the Eastern Gondwana margin during Cenomanian which was most probably caused by a dynamic change of the subduction zone through a « verticalization » of the slab. This event may be the result of the 99 Ma kinematic plate reorganization which probably led to subduction cessation along the Gondwana-Pacific plate boundary. A tectonic escape mechanism, in relation with the locking of the subduction zone by the Hikurangi Plateau, could also be responsible of the trench retreat leading to backarc extension. Phase 2: Regional Eocene-Oligocene uplift followed by rapid subsidence (3-4 km) of the system « Lord Howe Rise - FAB - Norfolk Ridge ». The structural style of this deformation leads us to suggest that detachment of the lower crust is the cause of subsidence. We therefore propose a model in

  10. Deformation of the Northwestern Okhotsk Plate: How is it happening?

    OpenAIRE

    Hindle, D.; Fujita, K.; Mackey, K.

    2009-01-01

    The Eurasia (EU) – North America (NA) plate boundary zone across Northeast Asia still presents many open questions within the plate tectonic paradigm. Constraining the geometry and number of plates or microplates present in the plate boundary zone is especially difficult because of the location of the EU-NA euler pole close to or even upon the EU-NA boundary. One of the major challenges remains the geometry of the Okhotsk plate (OK). whose northwestern portion terminates on ...

  11. Anisotropic elastic plates

    CERN Document Server

    Hwu, Chyanbin

    2010-01-01

    As structural elements, anisotropic elastic plates find wide applications in modern technology. The plates here are considered to be subjected to not only in plane load but also transverse load. In other words, both plane and plate bending problems as well as the stretching-bending coupling problems are all explained in this book. In addition to the introduction of the theory of anisotropic elasticity, several important subjects have are discussed in this book such as interfaces, cracks, holes, inclusions, contact problems, piezoelectric materials, thermoelastic problems and boundary element a

  12. An algorithm for full parametric solution of problems on the statics of orthotropic plates by the method of boundary states with perturbations

    Science.gov (United States)

    Penkov, V. B.; Ivanychev, D. A.; Novikova, O. S.; Levina, L. V.

    2018-03-01

    The article substantiates the possibility of building full parametric analytical solutions of mathematical physics problems in arbitrary regions by means of computer systems. The suggested effective means for such solutions is the method of boundary states with perturbations, which aptly incorporates all parameters of an orthotropic medium in a general solution. We performed check calculations of elastic fields of an anisotropic rectangular region (test and calculation problems) for a generalized plane stress state.

  13. Effective strength of incoming sediments and its implications for plate boundary propagation: Nankai and Costa Rica as type examples of accreting vs. erosive convergent margins

    Science.gov (United States)

    Kopf, Achim

    2013-11-01

    The location of the seaward tip of a subduction thrust controls material transfer at convergent plate margins, and hence global mass balances. At approximately half of those margins, the material of the subducting plate is completely underthrust so that no accretion or even subduction erosion takes place. Along the remaining margins, material is scraped off the subducting plate and added to the upper plate by frontal accretion. We here examine the physical properties of subducting sediments off Costa Rica and Nankai, type examples for an erosional and an accretionary margin, to investigate which parameters control the level where the frontal thrust cuts into the incoming sediment pile. A series of rotary-shear experiments to measure the frictional strength of the various lithologies entering the two subduction zones were carried out. Results include the following findings: (1) At Costa Rica, clay-rich strata at the top of the incoming succession have the lowest strength (μres = 0.19) while underlying calcareous ooze, chalk and diatomite are strong (up to μres = 0.43; μpeak = 0.56). Hence the entire sediment package is underthrust. (2) Off Japan, clay-rich deposits within the lower Shikoku Basin inventory are weakest (μres = 0.13-0.19) and favour the frontal proto-thrust to migrate into one particular horizon between sandy, competent turbidites below and ash-bearing mud above. (3) Taking in situ data and earlier geotechnical testing into account, it is suggested that mineralogical composition rather than pore-pressure defines the position of the frontal thrust, which locates in the weakest, clay mineral-rich (up to 85 wt.%) materials. (4) Smectite, the dominant clay mineral phase at either margin, shows rate strengthening and stable sliding in the frontal 50 km of the subduction thrust (0.0001-0.1 mm/s, 0.5-25 MPa effective normal stress). (5) Progressive illitization of smectite cannot explain seismogenesis, because illite-rich samples also show velocity

  14. Whether and What to Offshore?

    DEFF Research Database (Denmark)

    Jensen, Peter Ørberg; Pedersen, Torben

    In this article, we explore the idea that offshoring of services and technical work should be regarded as a dynamic process that evolves over time. Firms gradually move from offshoring of simple, standardized activities towards offshoring of advanced activities when they accumulate experience...... with offshoring, and this type of offshoring comes with an entirely different set of characteristics compared to traditional, cost-seeking offshoring. Based on a unique survey among the total population of firms in the eastern region of Denmark, we analyze some of the dynamics of this process through a model...... that incorporates two different aspects of the process of offshoring. First, we approach the question of whether to offshore and establish a baseline that investigates the determinants of firms’ participation—or lack thereof—in offshoring. Secondly, we approach the question of what to offshore and the subsequent...

  15. Offshore Q & A

    Institute of Scientific and Technical Information of China (English)

    AmberStohr

    2003-01-01

    Equity International, Asia, is a leading financial service provider in China, offering planning expertise for expatriates on investing their income and savings. I recently sat down with four senior wealth managers in Shanghai to discuss Equity's approach to offshore investing.

  16. A unified analysis of kinetic models for the problem of thermal creep based on the boundary conditions of Cercignani-Lampis for heterogeneous plates

    International Nuclear Information System (INIS)

    Rosa, Cinara Ewerling da; Knackfuss, Rosenei Felippe

    2013-01-01

    In this work is presented a series of numerical results and graphical comparisons of the physical quantities of interest such as: the velocity profile and the heat on profile. This formulation is developed for the problem of Thermal Creep, where the gas is moving between two parallel plates with different chemical constitutions (heterogeneous plates) due to a temperature gradient. The flow of a rarefied gas, is investigated with special attention to the gas-surface interaction, modeled by the Cercignani-Lampis kernel, that unlike Maxwell's scattering kernel, is defined in terms of two accommodation coefficients (normal and tangential) to represent the physical properties of the gas. The kinetic theory for rarefied gas dynamics, derived from the linearized Boltzmann equation, is developed in an unified approach, to the BGK model, S model, GJ model and MRS model. In the search for solutions to solve the problem of Thermal Creep with kernel of the Cercignani-Lampis, we used a analytical version of the discrete ordinates method (ADO) based on an arbitrary quadrature scheme, under which is determined a problem of eigenvalues and their respective separation constants. Numerical results are developed by the computer program FORTRAN. (author)

  17. Validation of three-dimensional incompressible spatial direct numerical simulation code: A comparison with linear stability and parabolic stability equation theories for boundary-layer transition on a flat plate

    Science.gov (United States)

    Joslin, Ronald D.; Streett, Craig L.; Chang, Chau-Lyan

    1992-01-01

    Spatially evolving instabilities in a boundary layer on a flat plate are computed by direct numerical simulation (DNS) of the incompressible Navier-Stokes equations. In a truncated physical domain, a nonstaggered mesh is used for the grid. A Chebyshev-collocation method is used normal to the wall; finite difference and compact difference methods are used in the streamwise direction; and a Fourier series is used in the spanwise direction. For time stepping, implicit Crank-Nicolson and explicit Runge-Kutta schemes are used to the time-splitting method. The influence-matrix technique is used to solve the pressure equation. At the outflow boundary, the buffer-domain technique is used to prevent convective wave reflection or upstream propagation of information from the boundary. Results of the DNS are compared with those from both linear stability theory (LST) and parabolized stability equation (PSE) theory. Computed disturbance amplitudes and phases are in very good agreement with those of LST (for small inflow disturbance amplitudes). A measure of the sensitivity of the inflow condition is demonstrated with both LST and PSE theory used to approximate inflows. Although the DNS numerics are very different than those of PSE theory, the results are in good agreement. A small discrepancy in the results that does occur is likely a result of the variation in PSE boundary condition treatment in the far field. Finally, a small-amplitude wave triad is forced at the inflow, and simulation results are compared with those of LST. Again, very good agreement is found between DNS and LST results for the 3-D simulations, the implication being that the disturbance amplitudes are sufficiently small that nonlinear interactions are negligible.

  18. Offshoring in textile industry

    OpenAIRE

    MONTÓN GARCÍA, JORGE

    2015-01-01

    [ EN] This project is about offshoring in the textile industry, focusing in the rights violated in this process, this concept can be defined as the moving of various operations of a company to another country for reasons such as lower labor costs or more favorable economic conditions in that other country. The project describes the evolution of offshoring, which started in 1960’s and has continued since then; it was characterized primarily by the transferring of factories from the develope...

  19. Screening Criteria and Considerations of Offshore Enhanced Oil Recovery

    Directory of Open Access Journals (Sweden)

    Pan-Sang Kang

    2016-01-01

    Full Text Available The application of enhanced oil recovery (EOR in offshore oil fields has received significant attention due to the potentially enormous amount of recoverable oil. However, EOR application offshore is in its very early stage due to conditions that are more complex than onshore oil fields, owing to the unique parameters present offshore. Therefore, successful EOR applications in offshore oil fields require different screening criteria than those for conventional onshore applications. A comprehensive database for onshore applications of EOR processes together with a limited offshore EOR application database are analyzed in this paper, and the important parameters for successful offshore application are incorporated into the new EOR screening criteria. In this paper, screening criteria to determine acceptable EOR processes for offshore fields, including hydrocarbon gas miscible, CO2 miscible, and polymer processes, are presented. Suggested screening criteria for these EOR processes comprise quantitative boundaries and qualitative considerations. Quantitative screening criteria are predominantly based on quantifiable data, such as oil and reservoir properties. Qualitative screening considerations mainly focus on the operational issues present offshore, including platform space constraints, limited disposal options, injectant availability, and flow assurance matters (including hydrate formation and difficulties in emulsion separation.

  20. Industrial opportunities - offshore

    International Nuclear Information System (INIS)

    Gerrits, D.J.

    1998-01-01

    Industrial opportunities available in the Canadian offshore petroleum industry are discussed. Oil has been produced offshore from Nova Scotia since 1992, and offshore from Newfoundland since 1997. Special needs that must be addressed in offshore operations in eastern Canada such as the cold North Atlantic environment, isolation, logistics, safety, and quality assurance, are examined. The most obvious opportunities lie with the designing, building and installing the facilities needed to extract oil and gas from beneath the sea floor and transport it to market. However, there are also opportunities in designing and fabricating clothing, customized food containers and other equipment for offshore needs. Short term opportunities also exist in the decommissioning of depleted production fields and their facilities. One of the greatest obstacles facing new entrants into the offshore oil and gas industry is the lack of a track record. To meet this challenge, the ability to seek out partners to pursue local and international opportunities through joint ventures, strategic alliances and technology sharing partnering arrangements is of great importance. It may be the difference between success and failure. 6 figs

  1. Offshore in depth

    Energy Technology Data Exchange (ETDEWEB)

    Ebdon, J F

    1968-08-01

    The world-wide scope of offshore areas is discussed. Offshore areas of the U.S. and the world are where one of the ''hottest'' hydrocarbon booms--drilling, production, and pipelining--are in action today. Most of the current activity in offshore exploration and drilling is crude oil directed. However, big non-associated natural gas finds have been made. Additionally, for every barrel of crude oil produced, either or both associated natural gas and dissolved natural gas are produced in some varying ratio as casinghead gas. Thus, with worldwide production of some 2.5-million bbl of crude oil per day from offshore areas of Free-World countries, there are vast volumes of casinghead natural gas produced, over and above that produced from non-associated natural gas wells to the seaward of land masses. If offshore gas of any classification is produced in commercial volumes close to onshore population centers, then the possibility of marketing is fairly good. If remote from population centers, it is usually flared or shut-in. The development of gas liquefaction and cryogenic tankers has started, but international ocean traffic in LNG is still in its infancy. Current offshore gas pipelines are described.

  2. Access Platforms for Offshore Wind Turbines Using Gratings

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.

    2008-01-01

    The paper deals with forces generated by a stationary jet on different types of gratings and a solid plate. The force reduction factors for the different gratings compared to the solid plate mainly depend on the porosity of the gratings, but the geometry of the grating is also of some importance........ The derived reduction factors are expected to be applicable to design of offshore wind turbine access platforms with gratings where slamming also is an important factor....

  3. Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

    Directory of Open Access Journals (Sweden)

    T. van der Werf

    2017-12-01

    Full Text Available The rheology of lower crust and its transient behavior in active strike-slip plate boundaries remain poorly understood. To address this issue, we analyzed a suite of granulite and lherzolite xenoliths from the upper Pleistocene–Holocene San Quintín volcanic field of northern Baja California, Mexico. The San Quintín volcanic field is located 20 km east of the Baja California shear zone, which accommodates the relative movement between the Pacific plate and Baja California microplate. The development of a strong foliation in both the mafic granulites and lherzolites, suggests that a lithospheric-scale shear zone exists beneath the San Quintín volcanic field. Combining microstructural observations, geothermometry, and phase equilibria modeling, we estimated that crystal-plastic deformation took place at temperatures of 750–890 °C and pressures of 400–560 MPa, corresponding to 15–22 km depth. A hot crustal geotherm of 40 ° C km−1 is required to explain the estimated deformation conditions. Infrared spectroscopy shows that plagioclase in the mafic granulites is relatively dry. Microstructures are interpreted to show that deformation in both the uppermost lower crust and upper mantle was accommodated by a combination of dislocation creep and grain-size-sensitive creep. Recrystallized grain size paleopiezometry yields low differential stresses of 12–33 and 17 MPa for plagioclase and olivine, respectively. The lower range of stresses (12–17 MPa in the mafic granulite and lherzolite xenoliths is interpreted to be associated with transient deformation under decreasing stress conditions, following an event of stress increase. Using flow laws for dry plagioclase, we estimated a low viscosity of 1.1–1.3×1020 Pa ⋅ s for the high temperature conditions (890 °C in the lower crust. Significantly lower viscosities in the range of 1016–1019 Pa ⋅ s, were estimated using flow laws for wet plagioclase. The

  4. Stretched flow of Carreau nanofluid with convective boundary ...

    Indian Academy of Sciences (India)

    journal of. January 2016 physics pp. 3–17. Stretched flow of Carreau nanofluid with ... fluid over a flat plate subjected to convective surface condition. ... the steady laminar boundary layer flow over a permeable plate with a convective boundary.

  5. Steady Boundary Layer Slip Flow along with Heat and Mass Transfer over a Flat Porous Plate Embedded in a Porous Medium

    Science.gov (United States)

    Aziz, Asim; Siddique, J. I.; Aziz, Taha

    2014-01-01

    In this paper, a simplified model of an incompressible fluid flow along with heat and mass transfer past a porous flat plate embedded in a Darcy type porous medium is investigated. The velocity, thermal and mass slip conditions are utilized that has not been discussed in the literature before. The similarity transformations are used to transform the governing partial differential equations (PDEs) into a nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is then reduced to a system of first order differential equations which was solved numerically by using Matlab bvp4c code. The effects of permeability, suction/injection parameter, velocity parameter and slip parameter on the structure of velocity, temperature and mass transfer rates are examined with the aid of several graphs. Moreover, observations based on Schmidt number and Soret number are also presented. The result shows, the increase in permeability of the porous medium increase the velocity and decrease the temperature profile. This happens due to a decrease in drag of the fluid flow. In the case of heat transfer, the increase in permeability and slip parameter causes an increase in heat transfer. However for the case of increase in thermal slip parameter there is a decrease in heat transfer. An increase in the mass slip parameter causes a decrease in the concentration field. The suction and injection parameter has similar effect on concentration profile as for the case of velocity profile. PMID:25531301

  6. Steady boundary layer slip flow along with heat and mass transfer over a flat porous plate embedded in a porous medium.

    Science.gov (United States)

    Aziz, Asim; Siddique, J I; Aziz, Taha

    2014-01-01

    In this paper, a simplified model of an incompressible fluid flow along with heat and mass transfer past a porous flat plate embedded in a Darcy type porous medium is investigated. The velocity, thermal and mass slip conditions are utilized that has not been discussed in the literature before. The similarity transformations are used to transform the governing partial differential equations (PDEs) into a nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is then reduced to a system of first order differential equations which was solved numerically by using Matlab bvp4c code. The effects of permeability, suction/injection parameter, velocity parameter and slip parameter on the structure of velocity, temperature and mass transfer rates are examined with the aid of several graphs. Moreover, observations based on Schmidt number and Soret number are also presented. The result shows, the increase in permeability of the porous medium increase the velocity and decrease the temperature profile. This happens due to a decrease in drag of the fluid flow. In the case of heat transfer, the increase in permeability and slip parameter causes an increase in heat transfer. However for the case of increase in thermal slip parameter there is a decrease in heat transfer. An increase in the mass slip parameter causes a decrease in the concentration field. The suction and injection parameter has similar effect on concentration profile as for the case of velocity profile.

  7. Seafloor morphology of the Eurasia-Nubia (Africa) plate boundary between the Tore-Madeira Rise and the Straits of Gibraltar: a case of coexistent Mesozoic through Present day features of tectonic, oceanographic and sedimentary origin

    Science.gov (United States)

    Terrinha, Pedro; Duarte, João.; Valadares, Vasco; Batista, Luis; Zitellini, Nevio; Grácia, Eulalia; Lourenço, Nuno; Rosas, Filipe; Roque, Cristina

    2010-05-01

    The joint use of more than 10.000 km multichannel seismic reflection profiles and 180.000km2 of multibeam swath bathymetry and backscatter allowed for a new vision of the seafloor tectonic and geomorphic processes of the area that encompasses the present day plate boundary between Africa and Eurasia, between the Gibraltar Straits and the Tore-Madeira Rise, in the southern sector of the North Atlantic Ocean. The interpretation of this data allowed for the detailed description of the seafloor morphology (i.e. a morphologic map) and the classification of the morphologic features in what respects the genetic process and age. It can be seen that in the same region coexist morphologic features that result from tectonic processes associated with the Triassic-Cretaceous break-up of Pangea, the Paleogene-Miocene compressive phase, the Miocene through Present subduction under the Gibraltar Arc (Gutscher et al., 2002), the Pliocene-Quaternary wrench tectonics and possible coeval plate boundary (Zitellini et al., 2009), the Present day mud volcanism and propagation of the compressive deformation along the West Continental Margin of Portugal (Terrinha et al., 2009). Interpretation of the seismic profiles together with the bathymetry allows the understanding of endogenous and exogenous processes that creates reliefs associated with active structures (related to the Miocene through Present compressive stress field). Other reliefs generated in Mesozoic times by analogous processes can be as well preserved as these active ones. In what concerns exogenous processes, the analysis of the two datasets (reflection seismics and bathymetry) allowed for the description of morphologic features associated with oceanic currents that interact with the seafloor forming these important features. As is the case of the well known active contourites but also less known features, like giant scours at 4 km water depth that have recently been described, suggesting the interaction of deep currents and

  8. Cretaceous to present kinematics of the Indian, African and Seychelles plates

    Science.gov (United States)

    Eagles, Graeme; Hoang, Ha H.

    2014-01-01

    An iterative inverse model of seafloor spreading data from the Mascarene and Madagascar basins and the flanks of the Carlsberg Ridge describes a continuous history of Indian-African Plate divergence since 84 Ma. Visual-fit modelling of conjugate magnetic anomaly data from near the Seychelles platform and Laxmi Ridge documents rapid rotation of a Seychelles Plate about a nearby Euler pole in Palaeocene times. As the Euler pole migrated during this rotation, the Amirante Trench on the western side of the plate accommodated first convergence and later divergence with the African Plate. The unusual present-day morphology of the Amirante Trench and neighbouring Amirante Banks can be related to crustal thickening by thrusting and folding during the convergent phase and the subsequent development of a spreading centre with a median valley during the divergent phase. The model fits FZ trends in the north Arabian and east Somali basins, suggesting that they formed in India-Africa Plate divergence. Seafloor fabric in and between the basins shows that they initially hosted a segmented spreading ridge that accommodated slow plate divergence until 71-69 Ma, and that upon arrival of the Deccan-Réunion plume and an increase to faster plate divergence rates in the period 69-65 Ma, segments of the ridge lengthened and propagated. Ridge propagation into the Indian continental margin led first to the formation of the Laxmi Basin, which accompanied extensive volcanism onshore at the Deccan Traps and offshore at the Saurashtra High and Somnath Ridge. A second propagation episode initiated the ancestral Carlsberg Ridge at which Seychelles-India and India-Africa Plate motions were accommodated. With the completion of this propagation, the plate boundaries in the Mascarene Basin were abandoned. Seafloor spreading between this time and the present has been accommodated solely at the Carlsberg Ridge.

  9. Offshore Supply Industry Dynamics

    DEFF Research Database (Denmark)

    Roslyng Olesen, Thomas

    This report is part of the research project “The competitive challenges and strategic development possibilities for The Blue Denmark”, which was launched in 2014. The project is funded by the Danish Maritime Fund and carried out by researchers at CBS Maritime which is a Business in Society Platform...... with companies in the maritime sector. This report “Offshore Supply Industry Dynamics – Business strategies in the offshore supply industry” is the second report in mapping project D. It examines the markets and business strategies of various suppliers and furthermore presents an analysis of the challenges...... at Copenhagen Business School with a focus on value creation in the maritime industries. The project embraces various maritime segments from shipping and offshore to ports and suppliers. The research questions for the individual projects have been formulated by researchers at CBS Maritime in cooperation...

  10. Offshoring R&D

    DEFF Research Database (Denmark)

    Hansen, Zaza Nadja Lee; Rasmussen, Lauge Baungaard

    2010-01-01

    Companies are increasingly offshoring R&D activities. Many firms, however, experience difficulties related to virtual teamwork across cultures and time zones. The research question is: How does increasing R&D offshoring impact transparency of communication structures and knowledge sharing? Using...... case studies from Danish multinational corporations with R&D activities in China, India or Eastern Europe this paper analyses the impact observed in these companies in regard to communication structures and knowledge sharing in management of offshored R&D activities. The findings show that companies...... attempt to increase transparency through formalisation of knowledge and clear communication structures. However, the influence of tacit knowledge, horizontal communication and culture seem largely overlooked. Therefore the authors suggest a context based approach to transparency accustomed...

  11. Offshore atomic power plants

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    Various merits of offshore atomic power plants are illustrated, and their systems are assessed. The planning of the offshore atomic power plants in USA is reviewed, and the construction costs of the offshore plant in Japan were estimated. Air pollution problem may be solved by the offshore atomic power plants remarkably. Deep water at low temperature may be advantageously used as cooling water for condensers. Marine resources may be bred by building artificial habitats and by providing spring-up equipments. In the case of floating plants, the plant design can be standardized so that the construction costs may be reduced. The offshore plants can be classified into three systems, namely artificial island system, floating system and sea bottom-based system. The island system may be realized with the present level of civil engineering, but requires the development of technology for the resistance of base against earthquake and its calculation means. The floating system may be constructed with conventional power plant engineering and shipbuilding engineering, but the aseismatic stability of breakwater may be a problem to be solved. Deep water floating system and deep water submerging system are conceivable, but its realization may be difficult. The sea bottom-based system with large caissons can be realized by the present civil engineering, but the construction of the caissons, stability against earthquake and resistance to waves may be problems to be solved. The technical prediction and assessment of new plant sites for nuclear power plants have been reported by Science and Technology Agency in 1974. The construction costs of an offshore plant has been estimated by the Ministry of International Trade and Industry to be yen71,026/kW as of 1985. (Iwakiri, K.)

  12. Offshore Wind Turbine Design

    DEFF Research Database (Denmark)

    Frandsen, Sten; Hansen, Erik Asp; Ibsen, Lars Bo

    2006-01-01

    Current offshore wind turbine design methods have matured to a 1st generation state, manifested in the draft of a possible standard, IEC 61400-3 (2005). It is now time to investigate the possibilities of improving existing methods. To do so in an efficient manner a clear identification of the most...... important uncertainty drivers specific for offshore wind turbine design loads is required. Describing the initial efforts in a Danish research project, the paper points to focal points for research and development. These are mainly: soil-structure interaction, improved modelling of wave loads from deep...

  13. Offshore rectenna feasbility

    Science.gov (United States)

    Freeman, J. W.; Hervey, D.; Glaser, P.

    1980-01-01

    A preliminary study of the feasibility and cost of an offshore rectenna to serve the upper metropolitan east coast was performed. A candidate site at which to build a 5 GW rectenna was selected on the basis of proximity to load centers, avoidance of shipping lanes, sea floor terrain, and relocated conditions. Several types of support structures were selected for study based initially on the reference system rectenna concept of a wire mesh ground screen and dipoles each with its own rectifier and filter circuits. Possible secondary uses of an offshore rectenna were examined and are evaluated.

  14. Offshoring and financial markets

    Directory of Open Access Journals (Sweden)

    Gianfranco Battisti

    2014-06-01

    Full Text Available The paper analyses the nature and extent of the offshore world, a grey area that is playing a major role in present-day economy. The main institutions moulding this peculiar environment are discussed: preferential tax regimes, tax havens and offshore financial centers. Their role in the globalised world is outlined after a scrutiny of the specialized literature, reports by non-governmental bodies and companies’ advertisings. Finally, we present a tentative reconstruction of its geographical organization, inclusive of cartographic representations of the main international networks.

  15. Offshore Supply Industry Dynamics

    DEFF Research Database (Denmark)

    Roslyng Olesen, Thomas

    The value chains for offshore oil and gas and offshore wind are both basically driven by the demand for energy. This is heavily dependent on a number of factors including the price of various energy sources and the policy making of the states which influence legislation, indirect subsidies...... of services including includes legal advice, financing, insurance etc. The two value chains have a number of activities in common. Both include (1) a tender and concession phase where the energy company obtains the right to explore and produce energy from the authorities. (2) An exploration phase where...

  16. Gela offshore field

    Energy Technology Data Exchange (ETDEWEB)

    Pagliughi, G

    1965-06-01

    The field of Gela, off the southern shore of Sicily, is the only producing offshore field in the Mediterranean. It produces from Triassic dolimite limestones of 434-m thickness, water level at -3517 m. It is a water-drive reservoir producing 10/sup 0/F API oil and has 79 wells, some of them on shore. Most offshore wells are directional wells from shore; there are also 2 fixed platforms and a special mobile platform. The wells are on pump (stroke, 72 in.; capacity 200 tons per day). The crude goes directly to a combination refinery-petrochemical complex at Gela.

  17. Cold plate

    Energy Technology Data Exchange (ETDEWEB)

    Marroquin, Christopher M.; O' Connell, Kevin M.; Schultz, Mark D.; Tian, Shurong

    2018-02-13

    A cold plate, an electronic assembly including a cold plate, and a method for forming a cold plate are provided. The cold plate includes an interface plate and an opposing plate that form a plenum. The cold plate includes a plurality of active areas arranged for alignment over respective heat generating portions of an electronic assembly, and non-active areas between the active areas. A cooling fluid flows through the plenum. The plenum, at the non-active areas, has a reduced width and/or reduced height relative to the plenum at the active areas. The reduced width and/or height of the plenum, and exterior dimensions of cold plate, at the non-active areas allow the non-active areas to flex to accommodate surface variations of the electronics assembly. The reduced width and/or height non-active areas can be specifically shaped to fit between physical features of the electronics assembly.

  18. Energy from Offshore Wind: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Musial, W.; Butterfield, S.; Ram, B.

    2006-02-01

    This paper provides an overview of the nascent offshore wind energy industry including a status of the commercial offshore industry and the technologies that will be needed for full market development.

  19. 2016 Offshore Wind Market Report

    Energy Technology Data Exchange (ETDEWEB)

    Musial, Walter [National Renewable Energy Lab. (NREL), Golden, CO (United States); Beiter, Philipp [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schwabe, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tian, Tian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Stehly, Tyler [National Renewable Energy Lab. (NREL), Golden, CO (United States); Spitsen, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-08-07

    The 2016 Offshore Wind Technologies Market Report is intended to provide stakeholders with quantitative information about the offshore wind market, technology, and cost trends in the United States and worldwide.

  20. Plating laboratory

    International Nuclear Information System (INIS)

    Seamster, A.G.; Weitkamp, W.G.

    1984-01-01

    The lead plating of the prototype resonator has been conducted entirely in the plating laboratory at SUNY Stony Brook. Because of the considerable cost and inconvenience in transporting personnel and materials to and from Stony Brook, it is clearly impractical to plate all the resonators there. Furthermore, the high-beta resonator cannot be accommodated at Stony Brook without modifying the set up there. Consequently the authors are constructing a plating lab in-house

  1. Pricing offshore wind power

    International Nuclear Information System (INIS)

    Levitt, Andrew C.; Kempton, Willett; Smith, Aaron P.; Musial, Walt; Firestone, Jeremy

    2011-01-01

    Offshore wind offers a very large clean power resource, but electricity from the first US offshore wind contracts is costlier than current regional wholesale electricity prices. To better understand the factors that drive these costs, we develop a pro-forma cash flow model to calculate two results: the levelized cost of energy, and the breakeven price required for financial viability. We then determine input values based on our analysis of capital markets and of 35 operating and planned projects in Europe, China, and the United States. The model is run for a range of inputs appropriate to US policies, electricity markets, and capital markets to assess how changes in policy incentives, project inputs, and financial structure affect the breakeven price of offshore wind power. The model and documentation are made publicly available. - Highlights: → We calculate the Breakeven Price (BP) required to deploy offshore wind plants. → We determine values for cost drivers and review incentives structures in the US. → We develop 3 scenarios using today's technology but varying in industry experience. → BP differs widely by Cost Scenario; relative policy effectiveness varies by stage. → The low-range BP is below regional market values in the Northeast United States.

  2. Offshore environmental aspects

    NARCIS (Netherlands)

    Lindeboom, H.J.; Degraer, S.

    2016-01-01

    The number of offshore wind farms (OWFs) is increasing rapidly, leading to questions about the cumulative environmental impact of such farms. The major impacts are caused by the noise produced in the building phase, the new hard substratum, the moving rotor blades, possible underwater noise in

  3. Floating offshore turbines

    DEFF Research Database (Denmark)

    Tande, John Olav Giæver; Merz, Karl; Schmidt Paulsen, Uwe

    2014-01-01

    metric of energy production per unit steel mass. Floating offshore wind turbines represent a promising technology. The successful operation of HyWind and WindFloat in full scale demonstrates a well advanced technology readiness level, where further development will go into refining the concepts, cost...

  4. Nearshore versus Offshore

    DEFF Research Database (Denmark)

    Klinge Jacobsen, Henrik; Hevia Koch, Pablo Alejandro; Wolter, Christoph

    Currently there exist high expectations for the development of wind energy, particularly in Europe, out of whichoffshore wind turbine developments will be central as tools to achieve current energy targets. The question betweennearshore and (far)-offshore is particularly relevant, both because of...

  5. Advanced Service Offshore Outsourcing

    DEFF Research Database (Denmark)

    Brandl, Kristin; Jensen, Peter D. Ørberg; Lind, Manya Jaura

    2018-01-01

    the capabilities, where the deficient development of one capability can be mitigated by the development of another capability (firm-internal determinants). Grounded in organization and service production theory, the paper contributes to the thematic literature on service offshoring and literature on organizational...

  6. 15 CFR 922.70 - Boundary.

    Science.gov (United States)

    2010-01-01

    ... a distance of approximately six nmi from the following islands and offshore rocks: San Miguel Island... Rock (the Islands). The seaward boundary coordinates are listed in Appendix A to this subpart. [74 FR... MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary § 922.70 Boundary. The...

  7. Offshore 2010. Final report; Offshore 2010. Sluttrapport

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    An overview of the accomplishments of the various projects that have received support from the Norwegian Research Council's program 'Offshore 2010'. The following projects are presented, some have English and some Norwegian project names: 'Critical parameters influencing inhibitor performance in multiphase flow', 'Development of the drilling optimization simulator (DDS) and a totally integrated drilling optimization system', 'Produksjonsoptimalisering og automatisk styring av broenner og roerledninger (PETRONICS)', 'Termisk isolerte undervannsroer for sikring av broenntransport over store avstander', 'Utvikling av magnetisk frekvensformer for styring av store subsea pumper paa havdyp ned mot 4000 meter', 'Flerfase stroemningsmaaler for permanent nedihulls installasjon', 'Hastighetsmaaling i flerfase stroemning ved passiv akustikk', 'Oil/water seperation offshore: optimized flow- and seperation behavior', 'Stroemningshastighet', 'A rock mechanics based reservoir simulation', 'MultiTool fase 2 - et flerbruksverktoey for nedihulls applikasjoner', 'Utvikling av undervanns olje-i-vann monitor for kontinuerlig maaling av lave oljekonsentrasjoner basert paa TR-LIFS', 'Subsea multipath ultrasonic liquid flow meter', 'Fluid characterization at elevated pressures and temperatures (Flucha II)'. The two main goals for the research program are 1. The development of new technology and competency in the field of downhole- and subsea processing and multiphase transportation, and 2. Innovation and commercialisation in small and medium sized companies (less than 100 employees). Some details on the financing and results are included (ml)

  8. Crossing Boundaries in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    across cultures, languages, organizational boundaries, time zones and geographical distances. The paper revises a framework of boundary spanning leadership practices developed for MNCs and adapts it to an offshore outsourcing context. It also contributes with reflections on how imbalances of resources......Western companies´ offshore outsourcing is increasingly being replaced by strategic partnerships that require closer collaboration between client and vendor. This paper addresses the question: How does a vendor company from an emergent market deal with inter-organizational boundary spanning...

  9. Basement configuration of KG offshore basin from magnetic anomalies

    Indian Academy of Sciences (India)

    of charnockites of neighbouring EGMB and onshore K–G basin areas indicates that EGMB geology. (charnockites ... Marine magnetic anomalies; offshore K–G basin; magnetic basement; extension of EGMB geology; continent– oceanic boundary. ..... of India; J. Australian Petroleum Exploration Association. 14 29–41.

  10. Scour Protection for Monopile by Concrete Plate

    DEFF Research Database (Denmark)

    Gilling, Lasse; Skúlason, Magnús

    A test programme has been performed to determine the scour around a monopile for an offshore wind turbine. The foundation is protected against scour with a concrete plate with various designs. The tests should be regarded as pilot tests previous to a detailed investigation. The tests has been...

  11. Component for articulated offshore loading towers

    Energy Technology Data Exchange (ETDEWEB)

    Backhaus, H.

    1980-09-01

    The construction of offshore natural gas liquefaction plants must be regarded as technically feasible and the marketing prospects for LNG - a source of clean burning energy - appear excellent. Nevertheless, the optimum loading procedure for LNG tankers in the - sometimes adverse - offshore environment is still a matter under discussion by the experts - with a tendency to adopt and adapt well-proven components from the offshore crude oil sector. Here, articulated towers are in use for tankerloading and the crude oil is pumped at ambient temperature through the cardan joint of the tower itself. In the case of the cryogenic liquid LNG, this method would entail intolerable risks. Leaks and subsequent LNG spills within the tower joint will cause low temperature-embrittlement and most likely damage the cardan connection at the tower's base plate on the sea bed. The described submarine joint for ultra-cold liquids, which has the same cardanic properties as the cardan joint of the tower is completely separated from the latter. Thus a cryogenic leakage in this submarine joint will under no circumstance reach and affect the tower cardan.

  12. Current trends in offshore technology

    International Nuclear Information System (INIS)

    Korsgaard, J.

    1994-01-01

    Although this is a technical symposium concerning advances in the technology of producing oil and gas offshore, a keynote address would not be complete without mentioning non-technical factors which are extremely important for the business of producing oil and gas offshore. These are political factors and economic factors. Offshore operations are an easy target for political forces that are opposed to marine operations involving the production and transfer of hydrocarbons. For example, the oil pollution act of 1990 was a reaction to the Exxon Valdez grounding in Alaska and this act has added significantly to the risk and cost of operating offshore. Another example of this is that it is becoming more and more difficult to dispose of produced water offshore. Producing oil and gas offshore is a business that competes with other energy sources such as coal and oil and gas from wells on land. The offshore oil can only compete with these other resources by providing the same product at a competitive price. Since offshore operations are inherently more costly than land operations, the offshore oil field or gas field must be significantly larger than a land field in order to be produced. Also the offshore oil field or gas field is more susceptible to environmental risks from weather. On a more positive note, there are technical developments which are taking place and have continuously taken place to make offshore oil and gas both more economic and safer to produce. These developments are briefly discussed

  13. A paleomagnetic investigation of vertical-axis rotations in coastal Sonora, Mexico: Evidence for distributed transtensional deformation during the Proto-Gulf shift from a subduction-dominated to transform-dominated plate boundary in the Gulf of California

    Science.gov (United States)

    Herman, Scott William

    The history of late Miocene (Proto-Gulf) deformation on the Sonoran margin of the Gulf of California is key to understanding how Baja California was captured by the Pacific plate and how strain was partitioned during the Proto-Gulf period (12.5-6 Ma). The Sierra el Aguaje and Sierra Tinajas del Carmen are located in southwestern coastal Sonora, Mexico, and represent the eastern rifted margin of the central Gulf of California. The ranges are composed of volcanic units and their corresponding volcaniclastic units which are the result of persistent magmatic activity between 20 and 8.8 Ma, including three packages of basalt and andesite that make excellent paleomagnetic recorders. Based on cross cutting relations and geochronologic data for pre-, syn-, and post-tectonic volcanic units, most of the faulting and tilting in the Sierra El Aguaje is bracketed between 11.9 and 9.0 Ma, thus falling entirely within Proto-Gulf time. A paleomagnetic investigation into possible vertical axis rotations in the Sierra el Aguaje has uncovered evidence of clockwise rotations between ~13º and ~105º with possible translations. These results are consistent with existing field relations, which suggest the presence of large (>45°) vertical axis rotations in this region. This evidence includes: a) abrupt changes in the strike of tilted strata in different parts of the range, including large domains characterized by E-W strikes b) ubiquitous NE-SW striking faults with left lateral-normal oblique slip, that terminate against major NW-trending right lateral faults, and c) obliquity between the general strike of tilted strata and the strike of faults. These rotations occurred after 12 Ma and largely prior to 9 Ma, thus falling into the Proto-Gulf period. Such large-scale rotations lend credence to the theory that the area inboard of Baja California was experiencing transtension during the Proto-Gulf period, rather than the pure extension that would be the result of strain partitioning

  14. Offshore concrete structures

    International Nuclear Information System (INIS)

    Lamas Pardo, M.; Carral Couce, L. M.

    2011-01-01

    In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shiphuidling industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

  15. Plate rotations, fault slip rates, fault locking, and distributed deformation in northern Central America from 1999-2017 GPS observations

    Science.gov (United States)

    Ellis, A. P.; DeMets, C.; Briole, P.; Cosenza, B.; Flores, O.; Guzman-Speziale, M.; Hernandez, D.; Kostoglodov, V.; La Femina, P. C.; Lord, N. E.; Lasserre, C.; Lyon-Caen, H.; McCaffrey, R.; Molina, E.; Rodriguez, M.; Staller, A.; Rogers, R.

    2017-12-01

    We describe plate rotations, fault slip rates, and fault locking estimated from a new 100-station GPS velocity field at the western end of the Caribbean plate, where the Motagua-Polochic fault zone, Middle America trench, and Central America volcanic arc faults converge. In northern Central America, fifty-one upper-plate earthquakes caused approximately 40,000 fatalities since 1900. The proximity of main population centers to these destructive earthquakes and the resulting loss of human life provide strong motivation for studying the present-day tectonics of Central America. Plate rotations, fault slip rates, and deformation are quantified via a two-stage inversion of daily GPS position time series using TDEFNODE modeling software. In the first stage, transient deformation associated with three M>7 earthquakes in 2009 and 2012 is estimated and removed from the GPS position time series. In Stage 2, linear velocities determined from the corrected GPS time series are inverted to estimate deformation within the western Caribbean plate, slip rates along the Motagua-Polochic faults and faults in the Central America volcanic arc, and the gradient of extension in the Honduras-Guatemala wedge. Major outcomes of the second inversion include the following: (1) Confirmation that slip rates on the Motagua fault decrease from 17-18 mm/yr at its eastern end to 0-5 mm/yr at its western end, in accord with previous results. (2) A transition from moderate subduction zone locking offshore from southern Mexico and parts of southern Guatemala to weak or zero coupling offshore from El Salvador and parts of Nicaragua along the Middle America trench. (3) Evidence for significant east-west extension in southern Guatemala between the Motagua fault and volcanic arc. Our study also shows evidence for creep on the eastern Motagua fault that diminishes westward along the North America-Caribbean plate boundary.

  16. Stability of diffusion flame formed in a laminar flat plate boundary layer. Effect of fuel dilution; Soryu heiban kyokai sonai ni keiseisareru kakusan kaen no anteisei. Nenryo kishaku no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, M [National Institute for Resources and Environment, Tsukuba (Japan); Ueda, T; Mizumoto, M [Keio University, Tokyo (Japan). Faculty of Science and Technology; Amari, T [Keio University, Tokyo (Japan)

    1998-10-25

    A stability limit of the diffusion flame with fuel injection from a porous wall in a laminar flat plate boundary layer is measured as functions of fuel (CH4) concentration of CH4/N2 injectant mixture ({chi}) and its injection velocity (v). The free stream velocity (U{infinity}) is set as 0.6 m/s. The thermal condition at the wall is controlled by setting temperature at the upstream end of the porous wall as a reference temperature. When v >20 mm/s, the flame becomes unstable with the separation of leading flame edge with decreasing {chi}. The value of {chi} at the stability limit is constant without regard to v as long as the wall temperature is kept constant. As the wall temperature is decreased the value of {chi} increases. The separation is supposed to take place as a result of the limit of the reaction rate. When v <20 mm/s, the flame becomes unstable with the oscillation. The value of {chi} at the stability limit increases drastically with decreasing v. The oscillation takes place mainly due to the repeat of the extinction due to heat loss to the wall and the flame propagation in the combustible layer. 10 refs., 8 figs., 1 tab.

  17. Offshore Wind Power

    DEFF Research Database (Denmark)

    Negra, Nicola Barberis

    reliability models, and a new model that accounts for all relevant factors that influence the evaluations is developed. According to this representation, some simulations are performed and both the points of view of the wind farm owner and the system operator are evaluated and compared. A sequential Monte...... Carlo simulation is used for these calculations: this method, in spite of an extended computation time, has shown flexibility in performing reliability studies, especially in case of wind generation, and a broad range of results which can be evaluated. The modelling is then extended to the entire power......The aim of the project is to investigate the influence of wind farms on the reliability of power systems. This task is particularly important for large offshore wind farms, because failure of a large wind farm might have significant influence on the balance of the power system, and because offshore...

  18. Offshore wind generators: realization?

    International Nuclear Information System (INIS)

    Roche, Catherine

    2012-01-01

    The author discusses the French legal context for the different aspects of the development of offshore wind farms in France: procedures related to electricity production installations (authorization or tender like what has been done for six sites), other administrative authorizations, and connection to the grid. Then, she addresses the various constraints: environmental, social and technical constraints (protected marine areas, constraints related to the tendering process), coast planning documents, tax policy. She finally discusses the installation dismantling

  19. Proceedings of the ENDOW workshop 'Offshore wakes: Measurements and modelling[Efficient Development of Offshore Windfarms

    Energy Technology Data Exchange (ETDEWEB)

    Barthelmie, R.J. (ed.)

    2002-03-01

    The papers presented in these Proceedings are the result of a workshop held at Risoe National Laboratory on March 7 and 8 2002 entitled 'Offshore Wakes: Measurements and Modelling'. The Workshop was arranged to showcase results of the European Community supported project 'Efficient Development of Offshore Windfarms (ENDOW)' and featured a series of eight presentations discussing modelling of wakes and boundary layers, existing and new measurements from offshore wind farms and how these will be linked in a new design tool and applied at planned offshore wind farms. In addition seven invited presentations covered a range of relevant topics from analytical approaches to fatigue and extreme loads in wind turbine clusters, current wake modelling in WAsP, optimising power production at Arklow Bank, Particle Image Velocimetry study of a wind turbine wake in a yaw, offshore wind measurements in Massachusetts, accuracy of SODAR measurements for wind energy and tidal influence of offshore wind speeds and turbulence. (au)

  20. Outsourcing software development offshore making IT work

    CERN Document Server

    Gold, Tandy

    2004-01-01

    THE OFFSHORE IMPERATIVECrunching the Offshore Numbers: What the Financials PortendWelcome to the Definitive Guide on Offshore OutsourcingSetting the Stage: The Compelling Offshore StoryOffshore Outsourcing versus Traditional IT OutsourcingChallenges of Offshore OutsourcingChapter SummaryGetting Started in OffshoreExecutive Support and Communications: The Key to SuccessA Look at an Example of Enlightened Leadership: Handling Employee Impact at a Northeast Utilities CompanyWell-Planned and Executed Communications: A Critical Success Factor for Offshore Program InitiationEstablishing the Offshore

  1. Wind energy in offshore grids

    DEFF Research Database (Denmark)

    Schröder, Sascha Thorsten

    special characteristics of offshore grids. With an operational real options approach, it is furthermore illustrated how different support schemes and connections to additional countries affect the investment case of an offshore wind farm and the income of the transmission system operator. The investment...... and investment implications under different regulatory frameworks are a hitherto underrepresented research field. They are addressed by this thesis. Offshore grids between several countries combine the absorption of wind energy with international power trading. However, the inclusion into an offshore grid......This cumulative PhD thesis deals with wind integration in offshore grids from an economic point of view. It is composed of a generic part and eight papers. As the topic has mostly been analysed with a focus on topology and technical issues until now, market-operational questions in offshore grids...

  2. The Hidden Costs of Offshoring

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Manning, Stephan; Pedersen, Torben

    2011-01-01

    of offshoring. Specifically, we propose that hidden costs can be explained by the combination of increasing structural, operational and social complexity of offshoring activities. In addition, we suggest that firm orientation towards organizational design as part of an offshoring strategy and offshoring......This study seeks to explain hidden costs of offshoring, i.e. unexpected costs resulting from the relocation of business tasks and activities outside the home country. We develop a model that highlights the role of complexity, design orientation and experience in explaining hidden costs...... experience moderate the relationship between complexity and hidden costs negatively i.e. reduces the cost generating impact of complexity. We develop three hypotheses and test them on comprehensive data from the Offshoring Research Network (ORN). In general, we find support for our hypotheses. A key result...

  3. Offshore and coastal dispersion (OCD) model. Users guide

    International Nuclear Information System (INIS)

    Hanna, S.R.; Schulman, L.L.; Paine, R.J.; Pleim, J.E.

    1984-09-01

    The Offshore and Coastal Dispersion (OCD) model was adapted from the EPA guideline model MPTER to simulate the effect of offshore emissions from point sources in coastal regions. Modifications were made to incorporate overwater plume transport and dispersion as well as changes that occur as the plume crosses the shoreline. Hourly meteorological data are needed from overwater and overland locations. Turbulence intensities are used but are not mandatory. For overwater dispersion, the turbulence intensities are parameterized from boundary-layer similarity relationships if they are not measured. Specifications of emission characteristics and receptor locations are the same as for MPTER; 250 point sources and 180 receptors may be used

  4. Decadal GPS Time Series and Velocity Fields Spanning the North American Continent and Beyond: New Data Products, Cyberinfrastructure and Case Studies from the EarthScope Plate Boundary Observatory (PBO) and Other Regional Networks

    Science.gov (United States)

    Phillips, D. A.; Herring, T.; Melbourne, T. I.; Murray, M. H.; Szeliga, W. M.; Floyd, M.; Puskas, C. M.; King, R. W.; Boler, F. M.; Meertens, C. M.; Mattioli, G. S.

    2017-12-01

    The Geodesy Advancing Geosciences and EarthScope (GAGE) Facility, operated by UNAVCO, provides a diverse suite of geodetic data, derived products and cyberinfrastructure services to support community Earth science research and education. GPS data and products including decadal station position time series and velocities are provided for 2000+ continuous GPS stations from the Plate Boundary Observatory (PBO) and other networks distributed throughout the high Arctic, North America, and Caribbean regions. The position time series contain a multitude of signals in addition to the secular motions, including coseismic and postseismic displacements, interseismic strain accumulation, and transient signals associated with hydrologic and other processes. We present our latest velocity field solutions, new time series offset estimate products, and new time series examples associated with various phenomena. Position time series, and the signals they contain, are inherently dependent upon analysis parameters such as network scaling and reference frame realization. The estimation of scale changes for example, a common practice, has large impacts on vertical motion estimates. GAGE/PBO velocities and time series are currently provided in IGS (IGb08) and North America (NAM08, IGb08 rotated to a fixed North America Plate) reference frames. We are reprocessing all data (1996 to present) as part of the transition from IGb08 to IGS14 that began in 2017. New NAM14 and IGS14 data products are discussed. GAGE/PBO GPS data products are currently generated using onsite computing clusters. As part of an NSF funded EarthCube Building Blocks project called "Deploying MultiFacility Cyberinfrastructure in Commercial and Private Cloud-based Systems (GeoSciCloud)", we are investigating performance, cost, and efficiency differences between local computing resources and cloud based resources. Test environments include a commercial cloud provider (Amazon/AWS), NSF cloud-like infrastructures within

  5. Development of boundary layers

    International Nuclear Information System (INIS)

    Herbst, R.

    1980-01-01

    Boundary layers develop along the blade surfaces on both the pressure and the suction side in a non-stationary flow field. This is due to the fact that there is a strongly fluctuating flow on the downstream blade row, especially as a result of the wakes of the upstream blade row. The author investigates the formation of boundary layers under non-stationary flow conditions and tries to establish a model describing the non-stationary boundary layer. For this purpose, plate boundary layers are measured, at constant flow rates but different interferent frequency and variable pressure gradients. By introducing the sample technique, measurements of the non-stationary boundary layer become possible, and the flow rate fluctuation can be divided in its components, i.e. stochastic turbulence and periodical fluctuation. (GL) [de

  6. The Economic Geography of Offshoring

    DEFF Research Database (Denmark)

    Ørberg Jensen, Peter D.; Pedersen, Torben

    2011-01-01

    when distinguishing between standardized and advanced activities. Asia attracts as many advanced activities as Western Europe while North America attracts more advanced activities even in manufacturing. Central and Eastern Europe attract offshoring in manufacturing and IT, but the activities...... that are offshored to these regions are typically not advanced. One important theoretical implication of this study is that a more detailed understanding of the nature of offshored activities is needed, since such attributes appear to be an important determinant of location choice....

  7. The Software Prototype as Digital Boundary Object – A Revelatory Longitudinal Innovation Case

    OpenAIRE

    Winkler, Maike; Huber, Thomas; Dibbern, Jens

    2014-01-01

    With the availability of lower cost but highly skilled software development labor from offshore regions, entrepreneurs from developed countries who do not have software development experience can utilize this workforce to develop innovative software products. In order to succeed in offshored innovation projects, the often extreme knowledge boundaries between the onsite entrepreneur and the offshore software development team have to be overcome. Prior research has proposed that boundary object...

  8. Offshore floating windmills

    International Nuclear Information System (INIS)

    1993-10-01

    The aim was to produce a general survey of the profitability of establishing floating offshore wind turbine arrays and to compare this with the cost and profitability of constructing offshore arrays with fixed foundations and arrays located on land sites. Aspects of design in all cases are described, also into relation to the special demands placed on dimensioning in relation to the types of location and foundation. The costs of the offshore arrays are evaluated in relation to capacity under conditions in Danish waters. The advantage of floating arrays is that they can be placed far out to sea where they can not be seen from the coast and thus not be considered to spoil the marine view. But as the water gets deeper the cost of floating foundations rises. It was found that it would not be technologically profitable to establish floating arrays at a depth of less than 30 - 40 meters which means that only the outer Danish waters can be taken into consideration. For depths of up to 70 meters, individual floating bases are more expensive than fixed ones but would be cheaper if a number of windmills could share the same anchor. For depths of more than 70 meters floating foundations would be the cheapest. The cost is dependent on the depth and distance from the coast and also on wind conditions. The main conclusion is that currently the cost of establishing wind turbine arrays in deeper outer waters on floating foundations is comparable to that of arrays sited at inner waters on solid foundations placed on the sea bed. (AB) (20 refs.)

  9. Offshore Wind Farms

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Hasager, Charlotte Bay; Courtney, Michael

    2015-01-01

    : the rotor, the nacelle, the tower, and the foundation. Further the determinations of the essential environmental conditions are treated: the wind field, the wave field, the sea current, and the soil conditions. The various options for grid connections, advantages, and disadvantages are discussed. Of special...... concern are the problems associated with locating the turbines close together in a wind farm and the problems of placing several large wind farms in a confined area. The environmental impacts of offshore wind farms are also treated, but not the supply chain, that is, the harbors, the installation vessels...

  10. Going for the play: Structural interpretation in offshore Congo

    Energy Technology Data Exchange (ETDEWEB)

    Platt, N.; Philip, P. (GECO-PRAKLA Exploration Services, Woking (United Kingdom)); Walter, S. (ARK Geophysics Ltd., Milton Keynes, (United Kingdom))

    1993-01-01

    Looking for new hydrocarbons in frontier areas, geologists and geophysicists use very trick in the book: plate tectonics, magnetic and gravity data, plain old geological horse sense and lots of seismic data. An interpretation team is followed, as they pick their way through a seismic survey shot in offshore Congo, Africa, searching for those areas (the plays) that show the greatest promise. 17 figs., 9 refs.

  11. Deposition and alteration of carbonaceous series within a Neotethyan rift at the western boundary of the Arabian plate: The late Permian Um Irna Formation, NW Jordan, a petroleum system

    Energy Technology Data Exchange (ETDEWEB)

    Dill, H.G.; Kus, J. [Federal Institute for Geosciences and Natural Resources, P.O. Box 51 01 53 D-30631 Hannover (Germany); Bechtel, A.; Gratzer, R. [Department of Applied Geosciences and Geophysics, University of Leoben, Peter Tunner Strasse 5, A-8700 Leoben (Austria); Abu Hamad, A.M.B. [Geology Department, University of Jordan, Amman 11942 (Jordan)

    2010-01-07

    During the late Permian (Kungurian to Kazanian) a Neotethyan rift basin evolved at the western boundary of the Arabian Plate, in what is called today the Dead Sea Valley of western Jordan. The break-up of Pangaea was accompanied by low-sinuosity sandy braided- to meandering-fluvial drainage systems which were fed by the uplift of the Arabian Shield and by poorly aerated swamps and ponds that concentrated plant debris of the Cathaysian floral province in the Um Irna Formation. These proximal wet fan sediments are overlain by a dry fan characterized by extensive reddish floodplain deposits, anastomosing channel systems and paleosols. The wet fan is underlain by Cambrian sandstones. These units serve as the top and bottom seals of the OM-bearing system of the Um Irna Formation. The sedimentary rocks of the OM-bearing Um Irna Formation underwent supergene, diagenetic and epigenetic hydrothermal alteration under an elevated geothermal gradient. The temperature increased from the time of deposition of the wet to the time of deposition of the dry fan and caused remobilization of manganese already pre-concentrated in the Cambrian footwall rocks of the rift basin. The anomalous heat regime may be accounted for as a predecessor stage of the Dead Sea Rift which is still active today. Oil seeps are found along faults and fractures near this deep-seated lineamentary fault zone. The deposition and alteration of the organic matter in this late Permian rift are of great consequence for oil generation in the region. Organic petrographic investigations revealed that organic-rich terrestrial carbonaceous and coal rich sediments of mainly of type III kerogen are dominant in the Um Irna Formation. In addition, aquatic liptinite rich sedimentary input (fresh water lake and/or lacustrine swamp) of type I kerogen is also noted. Coal derived organic matter occurs in the form of coaly particles with ranks from subbituminous A to high volatile bituminous C. Higher plant-derived macerals as

  12. Decommissioning of offshore installations

    Energy Technology Data Exchange (ETDEWEB)

    Oeen, Sigrun; Iversen, Per Erik; Stokke, Reidunn; Nielsen, Frantz; Henriksen, Thor; Natvig, Henning; Dretvik, Oeystein; Martinsen, Finn; Bakke, Gunnstein

    2010-07-01

    New legislation on the handling and storage of radioactive substances came into force 1 January 2011. This version of the report is updated to reflect this new regulation and will therefore in some chapters differ from the Norwegian version (see NEI-NO--1660). The Ministry of the Environment commissioned the Climate and Pollution Agency to examine the environmental impacts associated with the decommissioning of offshore installations (demolition and recycling). This has involved an assessment of the volumes and types of waste material and of decommissioning capacity in Norway now and in the future. This report also presents proposals for measures and instruments to address environmental and other concerns that arise in connection with the decommissioning of offshore installations. At present, Norway has four decommissioning facilities for offshore installations, three of which are currently involved in decommissioning projects. Waste treatment plants of this kind are required to hold permits under the Pollution Control Act. The permit system allows the pollution control authority to tailor the requirements in a specific permit by evaluating conditions and limits for releases of pollutants on a case-to-case basis, and the Act also provides for requirements to be tightened up in line with the development of best available techniques (BAT). The environmental risks posed by decommissioning facilities are much the same as those from process industries and other waste treatment plants that are regulated by means of individual permits. Strict requirements are intended to ensure that environmental and health concerns are taken into account. The review of the four Norwegian decommissioning facilities in connection with this report shows that the degree to which requirements need to be tightened up varies from one facility to another. The permit for the Vats yard is newest and contains the strictest conditions. The Climate and Pollution Agency recommends a number of measures

  13. Dutch offshore skills assessed

    Energy Technology Data Exchange (ETDEWEB)

    Schaap, P

    1988-11-01

    The position is described of the different Dutch industries involved in the oil and gas exploitation business in the North Sea. Mentioned are, in the first place, the activities of towing services Smit Tak, and Wijsmuller. A well known drilling contractor is Neddrill. Drilling rigs are often designed in cooperation with consulting engineers firms Protech International, Heerema Engineering, Global Engineering, KTI, Fluor, and Tebodin. Drilling rigs constructors Grootint, Mercon Steel Structures, Heerema Havenbedrijf, HCG, Boele, and IHC have a sound name in the offshore construction scene. Offshore contractors like Heerema, Smit Tak, Volker Stevin and Allseas Engineering should be mentioned too. Special attention is given to the operation of saving drilling rigs in the Ekofisk field. Years of exploitation of oil and gas from this field resulted in subsidence of the sea floor, which endangered the drilling rigs. Hydraudyne designed the hydraulic lifter necessary for this saving operation. Dutch firms in this field have an estimated yearly turnover of Dfl 3 x 10/sup 9/. 6 figs.

  14. Offshore Fish Community: Ecological Interactions

    Science.gov (United States)

    The offshore (>80 m) fish community of Lake Superior is made up of predominately native species. The most prominent species are deepwater sculpin, kiyi, cisco, siscowet lake trout, burbot, and the exotic sea lamprey. Bloater and shortjaw cisco are also found in the offshore zone...

  15. OFFSHORING FOR SUSTAINABLE VALUE MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Thaddeus Oforegbunam Ebiringa

    2014-05-01

    Full Text Available This paper evaluates offshoring as a strategic value management initiative using Cadbury Nigeria Plc as a case study. Through offshoring risks associated with inventory holding are hedged. A comparative analysis of in-house and offshored cost profiles as well as critical risk factors that affect firm value are evaluated. The result shows that offshoring led to immediate costs saving, freeing of funds previously held in inventory for other working capital investments as well as profitability for vendors. However, aside financial benefits to partners, it leads to increased stakeholders awareness, shared values, partnerships, teamwork and risk mitigation. It therefore follows that for sustainability of financial benefits of offshoring, concerted effort must be made by partners to ensure that critical drivers of value management are not compromised.

  16. Outsourcing/Offshoring Insights

    DEFF Research Database (Denmark)

    Tate, Wendy; Bals, Lydia

    2017-01-01

    Findings: Both the geographical and governance dimensions are part of the rightshoring decision which is an important conceptual foundation for this special issue, as it invited insightful pieces on all of these phenomena (e.g. outsourcing, insourcing, offshoring, reshoring), acknowledging...... for future research out of the six papers are summarized in Table III. There is ample opportunity to further shed light on these suggestions as well as to cover parts of the “rightshoring” framework presented, that remain less covered here (e.g. insourcing and/or reshoring). Practical implications: The array...... of potential “rightshoring” options fosters clarity about the phenomena studied and their implications. The main practical implications of the six papers are summarized in Table II. Originality/value: The overall conceptual framework highlights the positioning of the final papers included into the special...

  17. IBM Industry Practice: Challenges in Offshore Software Development from a Global Delivery Center

    Science.gov (United States)

    Musio, Ilario

    Offshore software development has greatly influenced competitiveness among IT companies in the last decade. Despite the fact that there are matured and developed offshoring methodologies, there is an ongoing tendency to look for new ways of improving them. Major IT corporations successfully rely on their offshore delivery centers for bridging the gap between communication and infrastructure boundaries. However, projects tend to fail, so problems have to be considered that arise between on- and offshore parts within the same corporation. Based on seven case studies from the industry, this paper describes experiences and challenges faced during the execution of offshore application development between IBM Switzerland and IBM India. Additionally, approaches on how they can be solved are proposed.

  18. Strain resolving method of composite plane plates

    Directory of Open Access Journals (Sweden)

    Ion FUIOREA

    2011-06-01

    Full Text Available The paper deals with the extension of isotropic plates problem to the case of composite plates. In order to perform it, the Kirchhoff-Love hypotheses were “softened” by some additional ones. Considering the constitutive laws for composite materials the stress functions were eliminated by using Cauchy equations. As a result a partial derivative equation in displacements was obtained. Finally the boundary condition formulation was extended for the case of complex composite plates.

  19. Noise from offshore wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Soendergaard, B.; Plovsing, B.

    2005-07-01

    Noise assessment of wind turbines through calculations is based on sound power levels measured according to e.g. IEC 61400-11. With larger wind turbines and distances some of the calculation models give erroneous results. Noise propagation over water is different from propagation over land. For that reason it is important be able to make valid noise assessments for offshore wind farms. A suggestion for an offshore measurement method is described and a survey of models for noise propagation offshore has been made. (au)

  20. Offshore wind power in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Holttinen, H. [VTT Energy, Espoo (Finland)

    1998-12-31

    The objectives of the project were to estimate the technical offshore wind power potential of the Gulf of Bothnia, with cost assessments, to study icing conditions and ice loads, and to design a foundation suitable for the environmental conditions. The technical offshore potential from Vaasa to Tornio is huge, more than 40 TWh/a, although the cost of offshore wind power is still higher than on land. Wind turbines have not previously been designed for the icing conditions found in Gulf of Bothnia and the recommendations for load cases and siting of megawatt-class turbines are an important result of the project. (orig.)

  1. Offshore Wind Turbine Foundation Design

    OpenAIRE

    Passon, Patrik; Branner, Kim; Larsen, Søren Ejling; Hvenekær Rasmussen, Jørgen

    2015-01-01

    Offshore vindenergi er i høj grad modnet i det seneste årti med en årligt installeret kapacitet på mere end1 GW. En vigtig faktor for den videre udvikling af offshore vindenergi i stor målestok, er en reduktion af de samlede udgifter til produceret energi. I betragtning af for eksempel faldet i olieprisen siden sommeren 2014 og dens fortsatte fald ind i 2015, er det endnu vigtigere at sænke omkostningerne til etablering af vedvarende energikilder såsom offshore vindenergi, for at nå frem til ...

  2. Domestic R&D and Offshoring

    DEFF Research Database (Denmark)

    Junge, Martin; Sørensen, Anders

    2017-01-01

    survey and register data. No evidence is found for a lower probability of own R&D after offshoring takes place compared to before. Moreover, offshoring does not lead to lower R&D intensity in general. However, firms that offshore R&D activity have larger R&D intensity after offshoring has taken place...

  3. Integration of Wave and Offshore Wind Energy in a European Offshore Grid

    DEFF Research Database (Denmark)

    Chozas, Julia Fernandez; Sørensen, H. C.; Korpås, M.

    2010-01-01

    of offshore renewable energy sources. According to this, the paper covers i) public and private initiatives for offshore transmission networks, ii) the synergies between the wave and the offshore wind energy sector within an offshore grid, iii) power transmission options for offshore generation and iv...

  4. The economics of offshore wind

    International Nuclear Information System (INIS)

    Green, Richard; Vasilakos, Nicholas

    2011-01-01

    This paper presents an overview of the main issues associated with the economics of offshore wind. Investment in offshore wind systems has been growing rapidly throughout Europe, and the technology will be essential in meeting EU targets for renewable energy in 2020. Offshore wind suffers from high installation and connection costs, however, making government support essential. We review various support policies used in Europe, concluding that tender-based feed-in tariff schemes, as used in Denmark, may be best for providing adequate support while minimising developers' rents. It may prove economic to build an international offshore grid connecting wind farms belonging to different countries that are sited close to each other. (author)

  5. Some characteristics of offshore operations

    Directory of Open Access Journals (Sweden)

    Popov Đorđe

    2011-01-01

    Full Text Available Offshore operations are not on the margins of the world economy. They are an integral part of modern business practice. They have become one of the most important instruments in the contemporary globalized financial system. Offshore operations and tax havens are not only conduits for tax avoidance and evasion but belong more broadly to the world of finance, for the business of managing the monetary resources of an organization, country or individuals. Offshore business operating in tax havens is at the heart of a particular type of globalization that is characterized by a growing gap between the very rich and everyone else. Tax havens are financial conduits that, in exchange for a fee, use their one principal asset- their sovereignty to serve a nonresident constituency of accountants and lawyers, bankers and financiers, who bring a demand for offshore operations.

  6. The economics of offshore wind

    Energy Technology Data Exchange (ETDEWEB)

    Green, Richard; Vasilakos, Nicholas [Department of Economics, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2011-02-15

    This paper presents an overview of the main issues associated with the economics of offshore wind. Investment in offshore wind systems has been growing rapidly throughout Europe, and the technology will be essential in meeting EU targets for renewable energy in 2020. Offshore wind suffers from high installation and connection costs, however, making government support essential. We review various support policies used in Europe, concluding that tender-based feed-in tariff schemes, as used in Denmark, may be best for providing adequate support while minimising developers' rents. It may prove economic to build an international offshore grid connecting wind farms belonging to different countries that are sited close to each other. (author)

  7. Learning Paths to Offshore Outsourcing

    DEFF Research Database (Denmark)

    Maskell, Peter; Pedersen, Torben; Petersen, Bent

    A corporation’s offshore outsourcing may be seen as the result of a discrete, strategic decision taken in response to an increasing pressure from worldwide competition. However, empirical evidence of a representative cross-sector sample of international Danish firms indicates that offshore sourcing...... in low-cost countries is best described as a learning-by-doing process in which the offshore outsourcing of a corporation goes through a sequence of stages towards sourcing for innovation. Initially, a corporation’s outsourcing is driven by a desire for cost minimization. Over a period of time...... the outsourcing experience lessens the cognitive limitations of decision-makers as to the advantages that can be achieved through outsourcing in low-cost countries: the insourcer/vendor may not only offer cost advantages, but also quality improvement and innovation. The quality improvements that offshore...

  8. The Organizational Design of Offshoring

    DEFF Research Database (Denmark)

    Ørberg Jensen, Peter D.; Larsen, Marcus M.; Pedersen, Torben

    2013-01-01

    Offshoring can be defined as the relocation of organizational tasks and services to foreign locations. At the same time as the scale and scope of offshoring have reached unprecedented levels in recent years, firms have increasingly been exposed to the challenges relating to managing an organizati...... implies an organizational reconfiguration consisting of three stages: disintegration, relocation and reintegration. We discuss the implications of this perspective and outline a research agenda....

  9. Offshore northern Europe, the challenges

    International Nuclear Information System (INIS)

    Bergseth, S.

    1996-01-01

    This paper relates to challenges of the offshore activity in the North Sea. It is appropriate to address these challenges in the context of generating values through efficient management of resources, markets, safety and technology, as the challenges lie therein. The petroleum industry is built to turn natural resources into market value, assuring broad benefits to stake holders and shareholders. In the following, the challenges facing the industry the industry offshore Northern Europe is examined on this background

  10. Optimization of material composition of nonhomogeneous plate for thermal stress relaxation making use of neural network. Analysis taking into account the relative heat transfer at boundary surfaces when subjected to unsteady heat supply

    International Nuclear Information System (INIS)

    Ootao, Yoshihiro; Kawamura, Ryuusuke; Tanigawa, Yoshinobu; Imamura, Ryuutarou

    1998-01-01

    In this study, a neural network is applied to optimization problems of material compositions for a nonhomogeneous plate with arbitrarily distributed and continuously varied material properties such as Functionally Graded Material. Unsteady temperature distribution for such nonhomogeneous plate is evaluated by taking into account the bounds of the number of the layers. Furthermore, the thermal stress components for an infinitely long nonhomogeneous plate are formulated under the mechanical condition of being traction free. As a numerical example, the plate composed of zirconium oxide and titanium alloy is considered. And, as the optimization problem of minimizing the thermal stress distribution, the numerical calculations are carried out making use of neural network, and the optimum material composition is determined taking into account the effect of temperature-dependency of material properties. Furthermore, the results obtained by neural network and ordinary nonlinear programming method are compared. (author)

  11. The Queen Charlotte-Fairweather Fault Zone - Geomorphology of a submarine transform fault, offshore British Columbia and southeastern Alaska

    Science.gov (United States)

    Walton, M. A. L.; Barrie, V.; Greene, H. G.; Brothers, D. S.; Conway, K.; Conrad, J. E.

    2017-12-01

    The Queen Charlotte-Fairweather (QC-FW) Fault Zone is the Pacific - North America transform plate boundary and is clearly seen for over 900 km on the seabed as a linear and continuous feature from offshore central Haida Gwaii, British Columbia to Icy Point, Alaska. Recently (July - September 2017) collected multibeam bathymetry, seismic-reflection profiles and sediment cores provide evidence for the continuous strike-slip morphology along the continental shelfbreak and upper slope, including a linear fault valley, offset submarine canyons and gullies, and right-step offsets (pull apart basins). South of central Haida Gwaii, the QC-FW is represented by several NW-SE to N-S trending faults to the southern end of the islands. Adjacent to the fault at the southern extreme and offshore Dixon Entrance (Canada/US boundary) are 400 to 600 m high mud volcanos in 1000 to 1600 m water depth that have plumes extending up 700 m into the water column and contain extensive carbonate crusts and chemosynthetic communities within the craters. In addition, gas plumes have been identified that appear to be directly associated with the fault zone. Surficial Quaternary sediments within and adjacent to the central and southern fault date either to the deglaciation of this region of the Pacific north coast (16,000 years BP) or to the last interstadial period ( 40,000 years BP). Sediment accumulation is minimal and the sediments cored are primarily hard-packed dense sands that appear to have been transported along the fault valley. The majority of the right-lateral slip along the entire QC-FW appears to be accommodated by the single fault north of the convergence at its southern most extent.

  12. Lightweight Efficient Offshore Fenders

    DEFF Research Database (Denmark)

    Banke, Lars; Simonsen, Bo Cerup

    1996-01-01

    At offshore platforms the purpose of fenders is to protect the oil-risers against minor accidental collisions from supply vessels.Normally the fender is designed by use of thin-walled tubes. However, the tube itself is not normally capable of resisting the impact load from of the boat. Therefore...... alternative designs are searched for the fender.Today, an often-used improvement of the fender is to fill it with grout or concrete. However, this improvement is not optimal since the fillingsincrease the weight of the finder beyond the crane capacity of the platform. This causes the need of crane boats...... for installation of the fender and eventually for removing it if new oil-risers are to be installed. The use of crane oats is expensive and weather dependent.Having these effects in mind a study of the energy absorption in the fender system, i.e. the fender itself and the frame, is needed for a furtherdevelopment...

  13. Offshore industry executives meet

    International Nuclear Information System (INIS)

    Burns, R.F.

    1993-01-01

    The future of the Gulf of Mexico is tied to the overall future of oil/gas on the international market as it relates to the US. Conquering this last frontier, possibly only through development of technology, was one of the themes covered in the 21st Annual Meeting of the National Ocean Industries Association held in early April, 1993 in Washington, D.C. Oil is the major source for foreign exchange but there are major uncertainties in predicting the future. The swing (imports vs. exports) is two million barrels per day. The big oil users (heavy industry) have reduced consumption. The last big uncertainty is the environmental policies of the West. Development of resources in the Gulf was the third record year in a row in 1992. The potential for hydrocarbon discoveries is significant, a substantial number of new fields have been made and significant discoveries are likely to continue. More than 100 trillion cubic feet of natural gas lies undiscovered offshore - 35% of undiscovered domestic resources. The oil potential exceeds nine billion barrels, more than any other basin except Alaska

  14. Corrugated megathrust revealed offshore from Costa Rica

    Science.gov (United States)

    Edwards, Joel H.; Kluesner, Jared; Silver, Eli A.; Brodsky, Emily E.; Brothers, Daniel; Bangs, Nathan L.; Kirkpatrick, James D.; Wood, Ruby; Okamato, Kristina

    2018-01-01

    Exhumed faults are rough, often exhibiting topographic corrugations oriented in the direction of slip; such features are fundamental to mechanical processes that drive earthquakes and fault evolution. However, our understanding of corrugation genesis remains limited due to a lack of in situ observations at depth, especially at subducting plate boundaries. Here we present three-dimensional seismic reflection data of the Costa Rica subduction zone that image a shallow megathrust fault characterized by corrugated, and chaotic and weakly corrugated topographies. The corrugated surfaces extend from near the trench to several kilometres down-dip, exhibit high reflection amplitudes (consistent with high fluid content/pressure) and trend 11–18° oblique to subduction, suggesting 15 to 25 mm yr−1 of trench-parallel slip partitioning across the plate boundary. The corrugations form along portions of the megathrust with greater cumulative slip and may act as fluid conduits. In contrast, weakly corrugated areas occur adjacent to active plate bending faults where the megathrust has migrated up-section, forming a nascent fault surface. The variations in megathrust roughness imaged here suggest that abandonment and then reestablishment of the megathrust up-section transiently increases fault roughness. Analogous corrugations may exist along significant portions of subduction megathrusts globally.

  15. Development of High Heat Input Welding Offshore Steel as Normalized Condition

    Science.gov (United States)

    Deng, Wei; Qin, Xiaomei

    The heavy plate used for offshore structure is one of the important strategic products. In recent years, there is an increasing demand for heavy shipbuilding steel plate with excellent weldability in high heat input welding. During the thermal cycle, the microstructure of the heat affected zone (HAZ) of plates was damaged, and this markedly reduced toughness of HAZ. So, how to improve the toughness of HAZ has been a key subject in the fields of steel research. Oxide metallurgy is considered as an effective way to improve toughness of HAZ, because it could be used to retard grain growth by fine particles, which are stable at the high temperature.The high strength steel plate, which satisfies the low temperature specification, has been applied to offshore structure. Excellent properties of the plates and welded joints were obtained by oxide metallurgy technology, latest controlled rolling and accelerated cooling technology using Ultra-Fast Cooling (an on-line accelerated cooling system). The 355MPa-grade high strength steel plates with normalizing condition were obtained, and the steels have excellent weldability with heat input energy of 79 287kJ/cm, and the nil ductility transition (NDT) temperature was -70°C, which can satisfy the construction of offshore structure in cold regions.

  16. Offshore pipelaying dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Gullik Anthon

    2010-02-15

    This thesis considers three issues regarding modeling of of offshore pipe laying dynamics. These are: (i) the formulation of an offshore pipeline installation operation as a control problem, (ii) the development and passivity analysis of a robotic pipe model for a submerged pipe string, suitable for real-time applications in closed- loop control systems, and (iii) the development and validation of a nonlinear FEM model for simulation and control of the elastic pipeline dynamics, including FEM dynamics of a pipeline combined with vessel dynamics, for simulation and control of pipe lay operations under dynamic positioning Pipeline installation is defined as the operation of positioning a pipeline along a reference path on the seabed from a surface vessel. In control terms, this can be stated as a path-following control problem, where the pipe touchdown point tracks the reference path. However, the only controllers for the touchdown point are the pay-out of pipe into the water, and the motion of the surface vessel. Considering that the pipe is an elastic body, and that both the pipe and the vessel are subject to environmental loads, the control problem that must be considered is a dynamic target-tracking problem, where the surface vessel must track a moving target position on the surface in order to control the position of the touchdown point. A target-tracking controller may be implemented as a guidance system, by extending the dynamic positioning system that is common for pipe lay vessels. An important component in the guidance system is the dynamic pipe model mapping touchdown and surface vessel position. Motivated by robotics, a compact system formulation is derived for the suspended pipeline by considering it as a hyper-redundant manipulator with an arbitrary number of links. This model captures the main dynamics of the pipe, including its geometric configuration and top tension. The model is in the state- space, and on a vectorial form using minimal coordinates

  17. IS OFFSHORING AN INTERNATIONAL PROCESS

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Gião

    2012-01-01

    Full Text Available This article proposes to analyze the applicability of transaction cost economics - TCE (Coase, 1937; Williamson, 1975, 1979 through its characteristic make-or-buy expression, considering the offshoring pace and emerging economy firms. The make-or-buy decision must be flexible enough to explain offshoring characteristics and developed and emerging economy firms scenarios. As secondary objectives, and to show the trail to the main purpose, two research questions were identified and discussed during the paper: Is offshoring process an international movement only from developed countries to emerging economies? Is the main reason of offshoring the looking for low-cost work / activities? To achieve the proposed objectives, the structure of this paper begins with a reasonable or acceptable definition of offshoring. Some reasons (or “the reason” for the process are also another important starting point. The majority of articles referee the idea that low-cost is the main reason for offshoring, and if it is correct, transaction cost economics seems to be a good basis for our analysis purpose and integrative intention. Also some literature connections between offshoring and TCE are presented and, naturally TCE is presented in highlights for understanding these connections. Ending this section, some different arguments based on newer researches are presented by some authors presenting another perspective as the main reason. After this theoretical approach, a scenario analysis and some discussions are presented based on all possible interactions among firm from developed (DC and emerging economies (EE and examples of international corporations are presented to clarify and improve the understanding of our research questions and to build new contributions to international business theory.

  18. Wind energy in offshore grids

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, S.T.

    2013-01-15

    This cumulative PhD thesis deals with wind integration in offshore grids from an economic point of view. It is composed of a generic part and eight papers. As the topic has mostly been analysed with a focus on topology and technical issues until now, market-operational questions in offshore grids and investment implications under different regulatory frameworks are a hitherto underrepresented research field. They are addressed by this thesis. Offshore grids between several countries combine the absorption of wind energy with international power trading. However, the inclusion into an offshore grid affects the economics of an offshore wind park. It is shown that the spot market income is lower if an offshore wind farm is placed in an interconnector and subject to nodal pricing instead of having a national affiliation. Moreover, congestion in the interconnector can prevent the wind farm from correcting its wind forecast errors in a specific onshore balancing group. An analytical approach with a transmission system operator and a wind farm as stakeholders illustrates resulting incentives for strategic behaviour. Depending on the regulatory regime, they may be inclined to announce more or less generation than expected at the closure of the day-ahead spot market. This can lead to a suboptimal utilisation of the infrastructure and associated socio-economic losses. These and possibly undesired reallocative effects between the parties can be avoided if the regulatory regime is adjusted to reflect special characteristics of offshore grids. With an operational real options approach, it is furthermore illustrated how different support schemes and connections to additional countries affect the investment case of an offshore wind farm and the income of the transmission system operator. The investment framework has also been addressed with a policy study about possible combinations of support schemes and international cooperation mechanisms between countries to achieve their

  19. Offshore Wind Energy Market Overview (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, I.

    2013-07-01

    This presentation describes the current international market conditions regarding offshore wind, including the breakdown of installation costs, how to reduce costs, and the physical siting considerations considered when planning offshore wind construction. The presentation offers several examples of international existing and planned offshore wind farm sites and compares existing international offshore resources with U.S. resources. The presentation covers future offshore wind trends and cites some challenges that the United States must overcome before it will be able to fully develop offshore wind sites.

  20. Offshore investments: Denmark shows the way

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    This article presents an overview of the use of wind power in Denmark and discusses the tremendous growth in the manufacture of wind turbines since 1981 with Denmark holding some 60% of the worlds' wind turbine market. The move to offshore wind farms is explained in terms of the shortage of land and the quality of the offshore wind, and details of the Tuno Knob pilot offshore wind farm are given. Offshore wind power in Europe, the challenges to offshore operations, the costs involved, environmental effects of the use of offshore wind, and the growing amount of wind power capacity are discussed

  1. Plate tectonics

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.

    's continental drift theory was later disproved, it was one of the first times that the idea of crustal movement had been introduced to the scientific community; and it has laid the groundwork for the development of modern plate tectonics. In the early... of the structure of the atom was to physical sciences and the theory of evolution was to the life sciences. Tectonics is the study of the forces within the Earth that give rise to continents, ocean basins, mountain ranges, earthquake belts and other large-scale...

  2. Create Your Plate

    Medline Plus

    Full Text Available ... Plate Share Create Your Plate ! Share: Seven Simple Steps to Create Your Plate It's simple and effective ... foods within each food category. Try these seven steps to get started: Using your dinner plate, put ...

  3. Deformation offshore Northern Chile monitored by a seafloor geodetic network (GeoSEA)

    Science.gov (United States)

    Hannemann, Katrin; Lange, Dietrich; Kopp, Heidrun; Petersen, Florian; Contreras-Reyes, Eduardo

    2017-04-01

    The Nazca-South American plate boundary around 21°S has last ruptured in an earthquake in 1877 and was identified as a seismic gap prior to the 2014 Iquique earthquake (Mw=8.1). The southern portion of this segment is still unbroken. The geodetic monitoring of the Chilean subduction zone is crucial to understand the deformation processes in this area. Most geodetic measurements rely on GPS and are therefore limited to onshore campaigns. In December 2015, we installed the GeoSEA (Geodetic Earthquake Observatory on the SEAfloor) array around 21°S of the Nazca-South American plate boundary with RV SONNE to extend the geodetic observations to the offshore areas. The GeoSEA array consists of autonomous acoustic seafloor transponders mounted on 4 m high tripods. These transponders are able to continuously measure the two-way travel time of acoustic signals between station pairs (baselines) and the properties of the sea water (sound speed, temperature and pressure) at each transponder. These measurements are used to retrieve the distances between the transponders and give insights into the deformation of the seafloor. At the Chilean subduction zone, we installed in total 23 transponders in 3 subarrays with interstation distances of up to 2500 m. On the middle continental slope in 2300 m water depth, an array consisting of 8 transponders measures across crustal faults seen in AUV mapping. A second array of 5 stations located on the outer rise monitors extension across normal plate-bending faults. The deepest deployment in 5000 m water depth located on the lower continental slope with 10 stations is designed to measure diffuse strain build-up. The transponders are intended to monitor the seafloor deformation for 3.5 years. In November 2016 during a cruise of RV Langseth, the first 11 months of data were successfully uploaded via an acoustic modem. Furthermore, an additional component of the network, GeoSURF, a self-steering autonomous vehicle (wave glider), was

  4. Dynamics of subduction and continental collision: Influence of the nature of the plate contact. Geologica Ultraiectina (284)

    NARCIS (Netherlands)

    De Franco, R.

    2008-01-01

    At convergent plate boundaries, the properties of the actual plate contact are important for the overall dynamics. Convergent plate boundaries both mechanically decouple and link tectonic plates and accommodate large amounts of strain. We investigate two fundamental physical states of the subduction

  5. Indonesian Landforms and Plate Tectonics

    Directory of Open Access Journals (Sweden)

    Herman Th. Verstappen

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v5i3.103The horizontal configuration and vertical dimension of the landforms occurring in the tectonically unstable parts of Indonesia were resulted in the first place from plate tectonics. Most of them date from the Quaternary and endogenous forces are ongoing. Three major plates – the northward moving Indo-Australian Plate, the south-eastward moving SE-Asian Plate and the westward moving Pacific Plate - meet at a plate triple-junction situated in the south of New Guinea’s Bird’s Head. The narrow North-Moluccan plate is interposed between the Asia and Pacific. It tapers out northward in the Philippine Mobile Belt and is gradually disappearing. The greatest relief amplitudes occur near the plate boundaries: deep ocean trenches are associated with subduction zones and mountain ranges with collision belts. The landforms of the more stable areas of the plates date back to a more remote past and, where emerged, have a more subdued relief that is in the first place related to the resistance of the rocks to humid tropical weathering Rising mountain ranges and emerging island arcs are subjected to rapid humid-tropical river erosions and mass movements. The erosion products accumulate in adjacent sedimentary basins where their increasing weight causes subsidence by gravity and isostatic compensations. Living and raised coral reefs, volcanoes, and fault scarps are important geomorphic indicators of active plate tectonics. Compartmental faults may strongly affect island arcs stretching perpendicular to the plate movement. This is the case on Java. Transcurrent faults and related pull-apart basins are a leading factor where plates meet at an angle, such as on Sumatra. The most complicated situation exists near the triple-junction and in the Moluccas. Modern research methods, such as GPS measurements of plate movements and absolute dating of volcanic outbursts and raised coral reefs are important tools. The mega-landforms resulting

  6. Canada-Nova Scotia Offshore Petroleum Board annual report, 1992-1993

    International Nuclear Information System (INIS)

    1993-06-01

    The Canada-Nova Scotia Offshore Petroleum Board was established as the agency responsible for the regulation of the hydrocarbon resources in the Nova Scotia offshore. The Board evaluates resource potential, administers petroleum exploration and production rights, approves offshore activities, and approves benefits and development plans. The main activities of the Board in 1992-1993 are summarized and financial statements are presented. Highlights include production of 572,300 m 3 of oil during the first production season of LASMO Nova Scotia Ltd.'s Cohasset development, the first commercial offshore oil production for Canada; four major resource evaluation projects in the Glenelg Field, the Laurentian sub-basin, the Fundy Rift Basin, and the Panuke Field; holding of discussions between Nova Scotia, Newfoundland, and Canada on the maritime boundary lines between respective offshore petroleum board jurisdictions, in the wake of a June 1992 determination of the disputed maritime boundary around St. Pierre et Miquelon; and amendments of certain safety-related legislation applicable to offshore operations. Employment benefits of the Cohasset project during 1992 totalled ca 470 Nova Scotians and 120 other Canadians. 3 tabs

  7. Offshore wind farm repowering optimization

    DEFF Research Database (Denmark)

    Hou, Peng; Enevoldsen, Peter; Hu, Weihao

    2017-01-01

    is focused on optimization of offshore wind farm repowering, which is one option for the wind farm owner at end of life for the offshore wind farm. The LCoE is used as the evaluation index to identify whether it is economical to invest in such a way. In an optimized repowering strategy, different types...... of wind turbines are selected to replace the original wind turbines to reconstruct the wind farm, which is demonstrated to be better than the refurbishment approach which replaces the old wind turbines with the same type. The simulations performed in this research reveal that the reconstructed wind farm......, which consists of multiple types of wind turbine, has a smaller LCoE (10.43%) than the refurbishment approach, which shows the superiority of the proposed method. This research contributes an optimization tool to the wind industry, which consequently drives down the cost of energy produced by offshore...

  8. Major hazards onshore and offshore

    International Nuclear Information System (INIS)

    1992-01-01

    This symposium continues the tradition of bringing together papers on a topic of current interest and importance in terms of process safety - in this case, Major Hazards Onshore and Offshore. Lord Cullen in his report on the Piper Alpha disaster has, in effect, suggested that the experience gained in the control of major hazards onshore during the 1980s should be applied to improve safety offshore during the 1990s. This major three-day symposium reviews what has been learned so far with regard to major hazards and considers its present and future applications both onshore and offshore. The topics covered in the programme are wide ranging and deal with all aspects of legislation, the application of regulations, techniques for evaluating hazards and prescribing safety measures in design, construction and operation, the importance of the human factors, and recent technical developments in protective measures, relief venting and predicting the consequences of fires and explosions. (author)

  9. Getting the most from offshoring

    DEFF Research Database (Denmark)

    Wæhrens, Brian Vejrum; Slepniov, Dmitrij; Johansen, John

    2014-01-01

    Tapping into global resources is supposed to improve performance and contribute to a firm’s competitive advantage. However, a high offshoring quota may also lead to erosion of the firm’s home base capabilities and have wider negative implications for both the home base site position and the firm...... as a whole. The purpose of this paper is to conceptualize this scenario and propose how its adverse impacts can be addressed. From previous studies we know that the roles and mandates of home based sites of offshoring companies are changing from broad scoped manufacturing towards innovation and network...... orchestration. On the basis of the findings from the survey, series of workshops and case studies of Danish companies presented in this paper, we seek to determine the longer term effects of offshoring for home based sites. We conceptualize the findings in a framework and close with discussing the need...

  10. Managing Hidden Costs of Offshoring

    DEFF Research Database (Denmark)

    Larsen, Marcus M.; Pedersen, Torben

    2014-01-01

    This chapter investigates the concept of the ‘hidden costs’ of offshoring, i.e. unexpected offshoring costs exceeding the initially expected costs. Due to the highly undefined nature of these costs, we position our analysis towards the strategic responses of firms’ realisation of hidden costs....... In this regard, we argue that a major response to the hidden costs of offshoring is the identification and utilisation of strategic mechanisms in the organisational design to eventually achieving system integration in a globally dispersed and disaggregated organisation. This is heavily moderated by a learning......-by-doing process, where hidden costs motivate firms and their employees to search for new and better knowledge on how to successfully manage the organisation. We illustrate this thesis based on the case of the LEGO Group....

  11. The baffle influence on sound radiation characteristics of a plate

    Directory of Open Access Journals (Sweden)

    Bao Liu

    2017-01-01

    Full Text Available The acoustic radiation characteristics of the baffle plates and unbaffle plates are calculated and compared by single-layer potential and double-layer potential. Based on the boundary integral equation, the sound pressure integral equation of the baffle and the baffle are deduced respectively. According to the boundary compatibility condition, the sound pressure and the vibration velocity of the plates are obtained. Further, the dynamic equation of the structure is substituted into the vibration equation in the form of the baffle plate and the baffle plate. The sound pressure difference and the displacement of a plate surface are in the form of the vibration mode superposition and the acoustic radiation impedance of the double integral form is obtained, which determines vibration mode coefficient and sound radiation parameters. The effect of the baffle on the acoustic radiation characteristics of the thin plate is analyzed by comparing the acoustic radiation parameters with the simple and simple rectangular plate in water.

  12. Structural factors controlling inter-plate coupling and earthquake rupture process

    Science.gov (United States)

    Kodaira, S.

    2007-05-01

    Recent availability of a large number of ocean bottom seismographs (OBSs), a large volume of air-gun array and a long streamer cable for academics provide several new findings of lithospheric scale structures in subduction seismogenic zones. JAMSTEC has acquired long-offset seismic data using a super-densely deploy OBS (i.e. 1 - 5 km spacing OBSs along 100 - 500 km long profiles) in the Nankai seismogeinc zone, SW. Japan, since 1999. Long-offset multichannel seismic (MCS) data by a two-ship experiment, as well as conventional 2D MCS data, have been also acquired at a part of the profiles. Some of those profiles have been designed as combined onshore - offshore profiles for imaging a land-ocean transition zone. One of the most striking findings is an image of several scales of subducted seamounts/ridges in the Nankai trough seismogenic zone. We detected the subducted seamount/ridges, which are 50 - 100 km wide, distributing from near trough axis to ~ 40 km deep beneath the Japanese island. From a point of seismogenic process, an important aspect is that those structures are strongly correlated with slip zones of magnitude 8-class earthquakes, i.e.; subducted seamounts/ridge control the rupture propagations. Moreover, the most recent seismic study crossing the segmentation boundary between M=8 class earthquakes detected a high seismic velocity body forming a strongly coupled patch at the segmentation boundary. The numerical simulation incorporating all those structures explained the historic rupture patterns, and shows the occurrence of a giant earthquake along the entire Nankai trough, a distance of over 600 km long (Mw=8.7). The growth processes of a rupture revealed from the simulation are; 1) prior to the giant earthquake, a small slow event (or earthquake) occurs near the segmentation boundary, 2) this accelerates a very slow slip (slower than the plate convergent rate), at the strong patch, which reduces a degree of coupling, 3) then a rupture easily propagates

  13. Levels of Outsourcing and Offshoring

    DEFF Research Database (Denmark)

    Madsen, Erik Skov; Slepniov, Dmitrij

    2011-01-01

    The purpose of this paper is to examine the evolution of offshoring and outsourcing over time and highlight strategic considerations underpinning this process in companies. On the basis of four case studies of Danish and German industrial companies, this paper develops a holistic framework...... conceptualizing various levels of outsourcing and offshoring as well as factors driving the transition between these levels. The framework adds to better understanding of the process and challenges the linear nature of it and suggests that ‘backsourcing’ and repatriation of activities should receive more...

  14. Mathematical methods for elastic plates

    CERN Document Server

    Constanda, Christian

    2014-01-01

    Mathematical models of deformation of elastic plates are used by applied mathematicians and engineers in connection with a wide range of practical applications, from microchip production to the construction of skyscrapers and aircraft. This book employs two important analytic techniques to solve the fundamental boundary value problems for the theory of plates with transverse shear deformation, which offers a more complete picture of the physical process of bending than Kirchhoff’s classical one.   The first method transfers the ellipticity of the governing system to the boundary, leading to singular integral equations on the contour of the domain. These equations, established on the basis of the properties of suitable layer potentials, are then solved in spaces of smooth (Hölder continuous and Hölder continuously differentiable) functions.   The second technique rewrites the differential system in terms of complex variables and fully integrates it, expressing the solution as a combination of complex ana...

  15. Offshore Energy Knowledge Exchange Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-04-12

    A report detailing the presentations and topics discussed at the Offshore Energy Knowledge Exchange Workshop, an event designed to bring together offshore energy industry representatives to share information, best practices, and lessons learned.

  16. The Capabilities of the Offshore Middlemen

    DEFF Research Database (Denmark)

    Mahnke, Volker; Wareham, Jonathan

    preliminary theoretical justification for the emergence of offshore intermediaries; describe how and why they develop intermediation capabilities; and offer initial evidence substantiating their function and processes in intermediating transnational offshoring relationships in software development...

  17. Analysis of hydraulic instability of ANS involute fuel plates

    International Nuclear Information System (INIS)

    Sartory, W.K.

    1991-11-01

    Curved shell equations for the involute Advanced Neutron Source (ANS) fuel plates are coupled to two-dimensional hydraulic channel flow equations that include fluid friction. A complete set of fluid and plate boundary conditions is applied at the entrance and exit and along the sides of the plate and the channel. The coupled system is linearized and solved to assess the hydraulic instability of the plates

  18. NEW OFFSHORE LOCATIONS IN THE EUROPEAN UNION

    Directory of Open Access Journals (Sweden)

    RADULESCU IRINA GABRIELA

    2014-05-01

    Full Text Available The offshore activity provides benefits for the host market and has positive effects on services, and on producers that use intermediate services. FDI in services has an important impact on the offshore activity, especially through transfer of technology. Many transnational companies have recognized the advantages of offshoring and the fact that it becomes a key globalization force. Recently, the Central European countries have become popular destinations among offshoring

  19. Global Production: The Case of Offshore Programming

    DEFF Research Database (Denmark)

    Nørbjerg, Jacob; Havn, Erling; Bansler, Jørgen P.

    1997-01-01

    of software is no exception.In this paper, we present a newly started research project on offshore program-ming, that is the practice of sending software development “offshore,” to India or other low wage areas. The project focuses on the organisation of offshore program-ming and, particularly, on the role...

  20. Grid Integration of Offshore Wind | Wind | NREL

    Science.gov (United States)

    Grid Integration of Offshore Wind Grid Integration of Offshore Wind Much can be learned from the existing land-based integration research for handling the variability and uncertainty of the wind resource Arklow Bank offshore wind park consists of seven GE Wind 3.6-MW wind turbines. Integration and

  1. Managing Risk Areas in Software Development Offshoring

    DEFF Research Database (Denmark)

    Persson, John Stouby; Schlichter, Bjarne Rerup

    2015-01-01

    Software companies are increasingly offshoring development to countries with high expertise at lower cost. Offshoring involves particular risk areas that if ignored increase the likelihood of failure. However, the offshoring client’s maturity level may influence the management of these risk areas...

  2. Transient LES of an offshore wind turbine

    Directory of Open Access Journals (Sweden)

    L. Vollmer

    2017-12-01

    Full Text Available The estimation of the cost of energy of offshore wind farms has a high uncertainty, which is partly due to the lacking accuracy of information on wind conditions and wake losses inside of the farm. Wake models that aim to reduce the uncertainty by modeling the wake interaction of turbines for various wind conditions need to be validated with measurement data before they can be considered as a reliable estimator. In this paper a methodology that enables a direct comparison of modeled with measured flow data is evaluated. To create the simulation data, a model chain including a mesoscale model, a large-eddy-simulation (LES model and a wind turbine model is used. Different setups are compared to assess the capability of the method to reproduce the wind conditions at the hub height of current offshore wind turbines. The 2-day-long simulation of the ambient wind conditions and the wake simulation generally show good agreements with data from a met mast and lidar measurements, respectively. Wind fluctuations due to boundary layer turbulence and synoptic-scale motions are resolved with a lower representation of mesoscale fluctuations. Advanced metrics to describe the wake shape and development are derived from simulations and measurements but a quantitative comparison proves to be difficult due to the scarcity and the low sampling rate of the available measurement data. Due to the implementation of changing synoptic wind conditions in the LES, the methodology could also be beneficial for case studies of wind farm performance or wind farm control.

  3. The offshore benthic fish community

    Science.gov (United States)

    Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

    2014-01-01

    Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are:

  4. Scour around an offshore windturbine

    NARCIS (Netherlands)

    Louwersheimer, W.F.; Verhagen, H.J.; Olthof, J.

    2007-01-01

    During the construction of the first Dutch offshore wind farm prototype measurements were performed. These measurements were aimed to monitor the behaviour of the granular filter layer of the scour protection around the mono-piles upon which the wind turbines are founded. These measurements were

  5. The Organizational Design of Offshoring

    DEFF Research Database (Denmark)

    Larsen, Marcus M.

    2014-01-01

    The general research question guiding this thesis is: What are the organizational consequences of offshoring? Increasingly firms are becoming caught up by the “harsh realities of offshoring” (Aron and Singh, 2005: 135). Many firms have begun to realize that managing an increasingly globally dispe...

  6. Getting the Most from Offshoring

    DEFF Research Database (Denmark)

    Slepniov, Dmitrij; Wæhrens, Brian Vejrum

    2015-01-01

    Tapping into global resources is supposed to improve performance and contribute to a firm’s competitive advantage. However, a high offshoring quota may also lead to erosion of the firm’s home base capabilities and have wider negative implications for both the home base site position and the firm...... and network orchestration....

  7. Modelling offshore sand wave evolution

    NARCIS (Netherlands)

    Nemeth, Attila; Hulscher, Suzanne J.M.H.; van Damme, Rudolf M.J.

    2007-01-01

    We present a two-dimensional vertical (2DV) flow and morphological numerical model describing the behaviour of offshore sand waves. The model contains the 2DV shallow water equations, with a free water surface and a general bed load formula. The water movement is coupled to the sediment transport

  8. California State Waters Map Series—Offshore of Monterey, California

    Science.gov (United States)

    Johnson, Samuel Y.; Dartnell, Peter; Hartwell, Stephen R.; Cochrane, Guy R.; Golden, Nadine E.; Watt, Janet T.; Davenport, Clifton W.; Kvitek, Rikk G.; Erdey, Mercedes D.; Krigsman, Lisa M.; Sliter, Ray W.; Maier, Katherine L.; Johnson, Samuel Y.; Cochran, Susan A.

    2016-08-18

    , a secondary fault within the distributed plate boundary, cuts through (and is roughly aligned with) Carmel Canyon, a submarine canyon in the southwest corner of the map area that is part of the Monterey Canyon system. The San Gregorio Fault Zone is part of a fault system that is present predominantly in the offshore for about 400 km, from Point Conception in the south (where it is known as the Hosgri Fault) to Bolinas and Point Reyes in the north.The offshore part of the map area primarily consists of relatively flat continental shelf, bounded on the west by the steep flanks of Carmel Canyon. Shelf width varies from 2 to 3 km in the southern part of the map area, near the mouth of Carmel Canyon, to 14 km in Monterey Bay. Bedrock beneath the shelf is overlain in many areas by variable amounts (0 to 16 m) of upper Quaternary shelf and nearshore sediments deposited as sea level fluctuated in the late Pleistocene. “Soft-induration,” unconsolidated sediment is the dominant (about 63 percent) habitat type on the continental shelf, followed by “hard-induration” rock and boulders (about 34 percent) and “mixed-induration” substrate (about 3 percent). At water depths of about 100 to 130 m, the shelf break approximates the shoreline during the sea-level lowstand of the Last Glacial Maximum, about 21,000 years ago.Carmel Canyon and other parts of the Monterey Canyon system in the map area extend from the shelf break to water depths that reach 1,600 m. Most of the extensive incision of the shelf break and canyon flanks probably occurred during repeated Quaternary sea-level lowstands. The relatively straight floor of Carmel Canyon notably is aligned with the San Gregorio Fault Zone. Mixed hard-soft substrate is the most common (about 51 percent) habitat type in Carmel Canyon; hard bedrock and soft, unconsolidated sediment cover about 40 percent and 9 percent of canyon habitat, respectively.This part of the central California coast is exposed to large North Pacific

  9. Emerging boundaries

    DEFF Research Database (Denmark)

    Løvschal, Mette

    2014-01-01

    of temporal and material variables have been applied as a means of exploring the processes leading to their socioconceptual anchorage. The outcome of this analysis is a series of interrelated, generative boundary principles, including boundaries as markers, articulations, process-related devices, and fixation...

  10. Changing Boundaries

    DEFF Research Database (Denmark)

    Brodkin, Evelyn; Larsen, Flemming

    2013-01-01

    project that is altering the boundary between the democratic welfare state and the market economy. We see workfare policies as boundary-changing with potentially profound implications both for individuals disadvantaged by market arrangements and for societies seeking to grapple with the increasing...

  11. Offshore concrete structures; Estructuras Offshore (mar adentro) de Hormigon

    Energy Technology Data Exchange (ETDEWEB)

    Lamas Pardo, M.; Carral Couce, L. M.

    2011-07-01

    In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shipbuilding industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

  12. Using altimetry and seafloor pressure data to estimate vertical deformation offshore: Vanuatu case study

    Science.gov (United States)

    Ballu, V.; Bonnefond, P.; Calmant, S.; Bouin, M.-N.; Pelletier, B.; Laurain, O.; Crawford, W. C.; Baillard, C.; de Viron, O.

    2013-04-01

    Measuring ground deformation underwater is essential for understanding Earth processes at many scales. One important example is subduction zones, which can generate devastating earthquakes and tsunamis, and where the most important deformation signal related to plate locking is usually offshore. We present an improved method for making offshore vertical deformation measurements, that involve combining tide gauge and altimetry data. We present data from two offshore sites located on either side of the plate interface at the New Hebrides subduction zone, where the Australian plate subducts beneath the North Fiji basin. These two sites have been equipped with pressure gauges since 1999, to extend an on-land GPS network across the plate interface. The pressure series measured at both sites show that Wusi Bank, located on the over-riding plate, subsides by 11 ± 4 mm/yr with respect to Sabine Bank, which is located on the down-going plate. By combining water depths derived from the on-bottom pressure data with sea surface heights derived from altimetry data, we determine variations of seafloor heights in a global reference frame. Using altimetry data from TOPEX/Poseidon, Jason-1, Jason-2 and Envisat missions, we find that the vertical motion at Sabine Bank is close to zero and that Wusi Bank subsides by at least 3 mm/yr and probably at most 11 mm/yr.This paper represents the first combination of altimetry and pressure data to derive absolute vertical motions offshore. The deformation results are obtained in a global reference frame, allowing them to be integrated with on-land GNSS data.

  13. Negotiating boundaries

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke

    2010-01-01

    to maintain the order of the home when managing disease and adopting new healthcare technology. In our analysis we relate this boundary work to two continuums of visibility-invisibility and integration-segmentation in disease management. We explore five factors that affect the boundary work: objects......, activities, places, character of disease, and collaboration. Furthermore, the processes are explored of how boundary objects move between social worlds pushing and shaping boundaries. From this we discuss design implications for future healthcare technologies for the home.......To move treatment successfully from the hospital to that of technology assisted self-care at home, it is vital in the design of such technologies to understand the setting in which the health IT should be used. Based on qualitative studies we find that people engage in elaborate boundary work...

  14. Mechanisms blocking the dynamics of the European offshore wind energy innovation system – Challenges for policy intervention

    International Nuclear Information System (INIS)

    Jacobsson, Staffan; Karltorp, Kersti

    2013-01-01

    Decarbonizing electricity production in the EU may necessitate building new “low-carbon” capacity (excluding nuclear investments) to deliver 3500 TWh by 2050. Offshore wind power has the potential to contribute substantially to fill this gap. Realizing this potential is, however, difficult since deployment offshore does not constitute a simple diversification by the onshore wind turbine industry to a new segment. This paper identifies factors obstructing the development of the northern European innovation system centered on offshore wind power, specifies a set of associated policy challenges and discusses various policy responses. - Highlights: • Offshore wind power has a strategic role in decarbonizing EU's supply of electricity. • There are numerous obstacles to deployment of offshore wind turbines. • We specify seven major policy challenges in diverse policy domains. • Managing these requires coordination of interventions across policy domains and national boundaries

  15. Offshore: Economic Deterrent or Necessity

    Directory of Open Access Journals (Sweden)

    Igor B. Turuev

    2014-01-01

    Full Text Available The downside of investment's addition rate in Russia, lack of capital investments result from "poor investment attractiveness". As a result, the companies' financial imbalance together with high investments risks lead to capital outflow from the country by virtue of offshores. Along with negative aspects connected with "financial oases" many advantages are given to the business community: lessening of tax payments, monetary privacy and confidentiality of operations. Taking in consideration the above and also the existence of specific international agreements concerning the avoidance of double taxation and offshore zones, the banner of the latter appears to be quite difficult and would divest the global economy of an important segment of global economic growth. The author performed a SWOT analysis of the role and the importance of offshores in international economy. Tolerant coexistence of local and global economic interests seems to be achievable by implementing a distinct circumspect and complex plan of measures aimed at the raise of the investment attractiveness of a country, for which the creation of "Skolkovo" and new Institutes for market development would not be sufficient. Transparent and oriented on business stability and safety provision of monitor and regulatory system, data interflow, improvement of prudential control on financial markets operations - are parts of measures that have to be accomplished in order to solve and exclude the problems associated with offshores. But the author also appeals to not forgetting that besides the offshores exists a number of such issues directly related to the outflow of capital as lowering of inflationary pace, enlargement of direct investment flow-in, support of social peace, which have to be handled for the purposes of improvement of domestic investment climate of countries with developing economy.

  16. Heat-flux gage measurements on a flat plate at a Mach number of 4.6 in the VSD high speed wind tunnel, a feasibility test (LA28). [wind tunnel tests of measuring instruments for boundary layer flow

    Science.gov (United States)

    1975-01-01

    The feasibility of employing thin-film heat-flux gages was studied as a method of defining boundary layer characteristics at supersonic speeds in a high speed blowdown wind tunnel. Flow visualization techniques (using oil) were employed. Tabulated data (computer printouts), a test facility description, and photographs of test equipment are given.

  17. Uncovering the Hidden Costs of Offshoring

    DEFF Research Database (Denmark)

    Larsen, Marcus M.; Manning, Stephan; Pedersen, Torben

    2013-01-01

    This study investigates estimation errors due to hidden costs—the costs of implementation that are neglected in strategic decision-making processes—in the context of services offshoring. Based on data from the Offshoring Research Network, we find that decision makers are more likely to make cost......-estimation errors given increasing configuration and task complexity in captive offshoring and offshore outsourcing, respectively. Moreover, we show that experience and a strong orientation toward organizational design in the offshoring strategy reduce the cost-estimation errors that follow from complexity. Our...

  18. Co-sourcing in software development offshoring

    DEFF Research Database (Denmark)

    Schlichter, Bjarne Rerup; Persson, John Stouby

    2013-01-01

    Software development projects are increasingly geographical distributed with offshoring, which introduce complex risks that can lead to project failure. Co-sourcing is a highly integrative and cohesive approach, seen successful, to software development offshoring. However, research of how co......-sourcing shapes the perception and alleviation of common offshoring risks is limited. We present a case study of how a certified CMMI-level 5 Danish software supplier approaches these risks in offshore co-sourcing. The paper explains how common offshoring risks are perceived and alleviated when adopting the co...

  19. CFD for wind and tidal offshore turbines

    CERN Document Server

    Montlaur, Adeline

    2015-01-01

    The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.

  20. Nearshore and offshore environmental effects monitoring at the Sable Offshore Energy project

    International Nuclear Information System (INIS)

    Hurley, G. V.

    2000-01-01

    A monitoring program to determine whether any temporary or permanent environmental perturbations may be attributable to the Sable offshore gas pipeline project as it approaches landfall at Goldboro through an outer bay is discussed, This nearshore region is an active fishing region for the residents of Goldboro, hence the concern about possible contamination. The monitoring project began with a baseline study, followed by monitoring the construction and the recovery period following construction, to ensure that any persistent changes to the nearshore aquatic environment were documented. The monitoring study included representatives of the fishing community to ensure that concerns are addressed early and on a continuing basis. At various phases of the project water properties,sediment modelling, the effects of construction on sea bottom conditions, benthic biota and cultivated mussels, water quality, phytoplankton, and resuspension of toxic cysts, terns and other seabirds were studied. Monitoring programs were also established for sea urchins and mussels, two important commercial species. Commercial-sized sea urchins showed a decrease of 60 per cent between 1998 and 1999 (i.e. the construction period). Recovery of sea urchin population in the immediate trench region will be the special focus of the post-construction monitoring phase. Mussel spat settlement and mussel tissue condition, lobster trapping, water properties, and bird behaviour showed no measurable changes during construction monitoring. In addition to these studies there is an ongoing offshore monitoring program in effect by Sable Offshore Energy Inc., put in place as a condition of approval of its Development Plan by the Canada-Nova Scotia Offshore Petroleum Board. This program monitors attributes such as water quality, suspended particulate matter in the benthic boundary layer, sediment quality, the benthic habitat and megafaunal community, shellfish body burden and taint, marine mammals and seabirds

  1. Is There Really A North American Plate?

    Science.gov (United States)

    Krill, A.

    2011-12-01

    Lithospheric plates are typically identified from earthquake epicenters and evidence such as GPS movements. But no evidence indicates a plate boundary between the North American and South American Plates. Some plate maps show them separated by a transform boundary, but it is only a fracture zone. Other maps show an "undefined plate boundary" or put no boundary between these two plates (check Google images). Early plate maps showed a single large American Plate, quite narrow east of the Caribbean Plate (Le Pichon 1968, Morgan 1968). The North and South American Plates became established by the leading textbook Earth (Press & Siever 1974). On their map, from a Scientific American article by John Dewey (1972), these new plates were separated by an "uncertain plate boundary." The reasons for postulating a North American Plate were probably more psychological than geological. Each of the other continents of the world had its own plate, and North American geologists naturally wanted theirs. Similarly, European geographers used to view Europe as its own continent. A single large plate should again be hypothesized. But the term American Plate would now be ambiguous ("Which plate, North or South?") Perhaps future textbook authors could call it the "Two-American Plate." Textbook authors ultimately decide such global-tectonic matters. I became aware of textbook authors' opinions and influence from my research into the history of Alfred Wegener's continental drift (see Fixists vs. Mobilists by Krill 2011). Leading textbook author Charles Schuchert realized that continental drift would abolish his cherished paleogeographic models of large east-west continents (Eria, Gondwana) and small oceans (Poseiden, Nereis). He and his junior coauthors conspired to keep drift evidence out of their textbooks, from the 1934-editions until the 1969-editions (Physical Geology by Longwell et al. 1969, Historical Geology by Dunbar & Waage 1969). Their textbooks ruled in America. Textbooks

  2. Upper-plate splay fault earthquakes along the Arakan subduction belt recorded by uplifted coral microatolls on northern Ramree Island, western Myanmar (Burma)

    Science.gov (United States)

    Shyu, J. Bruce H.; Wang, Chung-Che; Wang, Yu; Shen, Chuan-Chou; Chiang, Hong-Wei; Liu, Sze-Chieh; Min, Soe; Aung, Lin Thu; Than, Oo; Tun, Soe Thura

    2018-02-01

    Upper-plate structures that splay out from the megathrusts are common features along major convergent plate boundaries. However, their earthquake and tsunami hazard potentials have not yet received significant attention. In this study, we identified at least one earthquake event that may have been produced by an upper-plate splay fault offshore western Myanmar, based on U-Th ages of uplifted coral microatolls. This event is likely an earthquake that was documented historically in C.E. 1848, with an estimated magnitude between 6.8 and 7.2 based on regional structural characteristics. Such magnitude is consistent with the observed co-seismic uplift amount of ∼0.5 m. Although these events are smaller in magnitude than events produced by megathrusts, they may produce higher earthquake and tsunami hazards for local coastal communities due to their proximity. Our results also indicate that earthquake events with co-seismic uplift along the coast may not necessarily produce a flight of marine terraces. Therefore, using only records of uplifted marine terraces as megathrust earthquake proxies may overlook the importance of upper-plate splay fault ruptures, and underestimate the overall earthquake frequency for future seismic and tsunami hazards along major subduction zones of the world.

  3. National Offshore Wind Energy Grid Interconnection Study

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, John P. [ABB Inc; Liu, Shu [ABB Inc; Ibanez, Eduardo [National Renewable Energy Laboratory; Pennock, Ken [AWS Truepower; Reed, Greg [University of Pittsburgh; Hanes, Spencer [Duke Energy

    2014-07-30

    The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States. A total of 54GW of offshore wind was assumed to be the target for the analyses conducted. A variety of issues are considered including: the anticipated staging of offshore wind; the offshore wind resource availability; offshore wind energy power production profiles; offshore wind variability; present and potential technologies for collection and delivery of offshore wind energy to the onshore grid; potential impacts to existing utility systems most likely to receive large amounts of offshore wind; and regulatory influences on offshore wind development. The technologies considered the reliability of various high-voltage ac (HVAC) and high-voltage dc (HVDC) technology options and configurations. The utility system impacts of GW-scale integration of offshore wind are considered from an operational steady-state perspective and from a regional and national production cost perspective.

  4. Basement configuration of KG offshore basin from magnetic anomalies

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, V.; Swamy, K.V.; Raj, N.

    to Dept. of Science & Technology, New Delhi for granting the Junior Research Fel- lowship through Inspire Programme. This is NIO (CSIR) contribution no. 7132. References Aftalion M, Bowes D R, Dash B and Dempster T J 1988 Late proterozoic charnockites... anomaly map in figure 1. Keywords. Marine magnetic anomalies; offshore K–G basin; magnetic basement; extension of EGMB geology; continent– oceanic boundary. J. Earth Syst. Sci. 125, No. 3, April 2016, pp. 663–668 c© Indian Academy of Sciences 663 664 V...

  5. Dependence of offshore wind turbine fatigue loads on atmospheric stratification

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Larsen, Gunner Chr.; Ott, Søren

    2014-01-01

    The stratification of the atmospheric boundary layer (ABL) is classified in terms of the M-O length and subsequently used to determine the relationship between ABL stability and the fatigue loads of a wind turbine located inside an offshore wind farm. Recorded equivalent fatigue loads, representi...... conditions. In general, impact of ABL stratification is clearly seen on wake affected inflow cases for both blade and tower fatigue loads. However, the character of this dependence varies significantly with the type of inflow conditions – e.g. single wake inflow or multiple wake inflow....

  6. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors in...... approach with pattern matching is a way to shed light on the tacit local knowledge that organizational actors cannot articulate and that an exclusively inductive research is not likely to unveil....

  7. Tuno Knob Offshore Wind Farm

    International Nuclear Information System (INIS)

    Madsen, P.S.

    1996-01-01

    In 1995 Midtkraft Power Company built Denmark's second offshore wind farm as a demonstration project. The project purpose is first of all to investigate the environmental aspects of offshore wind energy. The two primary objects are to study the impact on bird life and to test different methods for predicting the visual effect. The wind farm consists of 10 pitch-regulated Vestas V39 500 kW wind turbines placed on box caisson foundations in a shallow water area 6 km east of Jutland. The project has been implemented successfully under a very narrow time schedule, and during the first 6 months in operation, the production has been approx. 30% higher than expected. (author)

  8. Offshore Wind Energy in Denmark

    DEFF Research Database (Denmark)

    Möller, Bernd; Hong, Lixuan; Hvelplund, Frede

    for Denmark and invites to reconsider the technological and institutional choices made. Based on a continuous resource-economic model operating in a geographical information systems (GIS) environment, which describes resources, costs and area constraints in a spatially explicit way, the relation between......Offshore wind energy has developed in terms of turbine and project size, and currently undergoes a significant up-scaling to turbines and parks at greater distance to shore and deeper waters. Expectations to the positive effect of economies of scale on power production costs, however, have...... availability of locations, driven by accelerating requirements of environmental concern, park size and public acceptance, is one important driver. Mounting risk of mega-projects and the infinite demand for renewable energy is another likely cause. The present paper addresses the scale of offshore wind parks...

  9. Radiographic inspection on offshore platforms

    International Nuclear Information System (INIS)

    Soares, Sergio Damasceno; Sperandio, Augusto Gasparoni

    1994-01-01

    One of the great challenges for non-destructive inspection is on offshore platforms, where safety is a critical issue. Inspection by gammagraphy is practically forbidden on the platform deck due to problems to personnel safety and radiological protection. Ir-192 sources are used and the risk of an accident with loss of radioisotope must be considered. It is unfeasible to use gammagraphy, because in case of an accident the rapid evacuation from the platform would be impossible. This problem does not occur when X-ray equipment is used as the radiation source. The limited practicality and portability of the X-ray equipment have prevented its use as a replacement for the gammagraphy. This paper presents the preliminary tests to see the viable use of radiographic tests with constant potential on offshore platforms. (author). 2 refs., 1 fig., 2 tabs, 3 photos

  10. Motion of the Rivera plate since 10 Ma relative to the Pacific and North American plates and the mantle

    Science.gov (United States)

    DeMets, Charles; Traylen, Stephen

    2000-03-01

    To better understand the influence of Rivera plate kinematics on the geodynamic evolution of western Mexico, we use more than 1400 crossings of seafloor spreading magnetic lineations along the Pacific-Rivera rise and northern Mathematician ridge to solve for rotations of the Rivera plate relative to the underlying mantle and the Pacific and North American plates at 14 times since 9.9 Ma. Our comparison of magnetic anomaly crossings from the undeformed Pacific plate to their counterparts on the Rivera plate indicates that significant areas of the Rivera plate have deformed since 9.9 Ma. Dextral shear along the southern edge of the plate from 3.3-2.2 Ma during a regional plate boundary reorganization deformed the Rivera plate farther into its interior than previously recognized. In addition, seafloor located north of two rupture zones within the Rivera plate sutured to North America after 1.5 Ma. Anomaly crossings from these two deformed regions thus cannot be used to reconstruct motion of the Rivera plate. Finite rotations that best reconstruct Pacific plate anomaly crossings onto their undeformed counterparts on the Rivera plate yield stage spreading rates that decrease gradually by 10% between 10 and 3.6 Ma, decrease rapidly by 20% after ˜3.6 Ma, and recover after 1 Ma. The slowdown in Pacific-Rivera seafloor spreading at 3.6 Ma coincided with the onset of dextral shear across the then-incipient southern boundary of the Rivera plate with the Pacific plate. The available evidence indicates that the Rivera plate has been an independent microplate since at least 10 Ma, contrary to published assertions that it fragmented from the Cocos plate at ˜5 Ma. Motion of the Rivera plate relative to North America has changed significantly since 10 Ma, in concert with significant changes in Pacific-Rivera motion. A significant and robust feature of Rivera-North America motion not previously recognized is the cessation of margin-normal convergence and thus subduction from 2

  11. Sinking offshore platform. Nedsenkbar fralandsplatform

    Energy Technology Data Exchange (ETDEWEB)

    Einstabland, T.B.; Olsen, O.

    1988-12-19

    The invention deals with a sinking offshore platform of the gravitational type designed for being installed on the sea bed on great depths. The platform consists of at least three inclining pillars placed on a foundation unit. The pillars are at the upper end connected to a tower structure by means of a rigid construction. The tower supports the platform deck. The rigid construction comprises a centre-positioned cylinder connected to the foundation. 11 figs.

  12. Panorama 2016 - Offshore wind power

    International Nuclear Information System (INIS)

    Vinot, Simon

    2015-11-01

    While onshore wind power is a rapidly growing global industry, the offshore wind power market remains in its consolidation and globalization phase. This most mature of renewable marine energies continues to develop and can no longer be considered a niche industry. This fact sheet evaluates the market over the last several years, looking at its potential and its current rank in terms of electricity production costs. (author)

  13. Panorama 2013 - Offshore wind power

    International Nuclear Information System (INIS)

    Vinot, Simon

    2012-10-01

    While onshore wind power is already a well-developed global industry, offshore wind power is still in the consolidation and globalization phase. The most mature of marine renewable energies is beginning to venture off the European coast and even to other continents, driven by public policies and the ever increasing number of players joining this promising market, which should evolve into deeper waters thanks to floating structures. (author)

  14. Climate and Offshore Energy Resources.

    Science.gov (United States)

    1980-12-30

    SECuRITY CL.ASSIPIcaTIoN OF, TIns PA@elm VaeVa CLMATE ANID OFFSHORE ENERGY RESOUACES A distinguished group of government officials, scientists, engineers...about the mech- anisms of climatic systems, and gaining a better understanding of the impact of climatic change on human resources.* He continued by...atmospheric constit- uents, but he particularly emphasized " changes " in C02. He suggested that the atmospheric conditions may be better now than they were half

  15. Techno-Economic Comparison of Onshore and Offshore Underground Coal Gasification End-Product Competitiveness

    Directory of Open Access Journals (Sweden)

    Natalie Christine Nakaten

    2017-10-01

    Full Text Available Underground Coal Gasification (UCG enables the utilisation of coal reserves that are currently not economically exploitable due to complex geological boundary conditions. Hereby, UCG produces a high-calorific synthesis gas that can be used for generation of electricity, fuels and chemical feedstock. The present study aims to identify economically competitive, site-specific end-use options for onshore and offshore produced UCG synthesis gas, taking into account the capture and storage (CCS and/or utilisation (CCU of resulting CO 2 . Modelling results show that boundary conditions that favour electricity, methanol and ammonia production expose low costs for air separation, high synthesis gas calorific values and H 2 /N 2 shares as well as low CO 2 portions of max. 10%. Hereby, a gasification agent ratio of more than 30% oxygen by volume is not favourable from economic and environmental viewpoints. Compared to the costs of an offshore platform with its technical equipment, offshore drilling costs are negligible. Thus, uncertainties related to parameters influenced by drilling costs are also negligible. In summary, techno-economic process modelling results reveal that scenarios with high CO 2 emissions are the most cost-intensive ones, offshore UCG-CCS/CCU costs are twice as high as the onshore ones, and yet all investigated scenarios except from offshore ammonia production are competitive on the European market.

  16. Offshore oil: Correctness of perspective

    International Nuclear Information System (INIS)

    Burns, R.F.

    1993-01-01

    Except for the Gulf of Mexico, the offshore oil industry has been virtually banned from the US Exclusive Economic Zone for ten years. The oil potential in Alaska's Arctic National Wildlife Refuge (ANWR) is also off limits. The Gulf of Mexico is the only place with prospects for future success and a number of companies both large and small are determined to move forward. The depressed price of oil does not encourage development but recently gas prices in the US have increased, making offshore gas development more feasible. Perhaps most significant is development and application of new technology and more intense management to make sure it works. The offshore oil companies and support industries have made significant technological advances, expending over and above the dollars paid in taxes, lease fees, and royalties. The ocean industries harbor a great reservoir of high technology knowledge. They have demonstrated the ability to successfully meet a vast array of challenges in exploring for, drilling, and producing oil and gas in extreme conditions. These facts beg the question as to the rational basis of each and every regulation and the ban on drilling

  17. World offshore energy loss statistics

    International Nuclear Information System (INIS)

    Kaiser, Mark J.

    2007-01-01

    Offshore operations present a unique set of environmental conditions and adverse exposure not observed in a land environment taking place in a confined space in a hostile environment under the constant danger of catastrophe and loss. It is possible to engineer some risks to a very low threshold of probability, but losses and unforeseen events can never be entirely eliminated because of cost considerations, the human factor, and environmental uncertainty. Risk events occur infrequently but have the potential of generating large losses, as evident by the 2005 hurricane season in the Gulf of Mexico, which was the most destructive and costliest natural disaster in the history of offshore production. The purpose of this paper is to provide a statistical assessment of energy losses in offshore basins using the Willis Energy Loss database. A description of the loss categories and causes of property damage are provided, followed by a statistical assessment of damage and loss broken out by region, cause, and loss category for the time horizon 1970-2004. The impact of the 2004-2005 hurricane season in the Gulf of Mexico is summarized

  18. Offshore Blowouts, Causes and Trends

    Energy Technology Data Exchange (ETDEWEB)

    Holand, P

    1996-02-01

    The main objective of this doctoral thesis was to establish an improved design basis for offshore installations with respect to blowout risk analyses. The following sub objectives are defined: (1) Establish an offshore blowout database suitable for risk analyses, (2) Compare the blowout risk related to loss of lives with the total offshore risk and risk in other industries, (3) Analyse blowouts with respect to parameters that are important to describe and quantify blowout risk that has been experienced to be able to answer several questions such as under what operations have blowouts occurred, direct causes, frequency of occurrence etc., (4) Analyse blowouts with respect to trends. The research strategy applied includes elements from both survey strategy and case study strategy. The data are systematized in the form of a new database developed from the MARINTEK database. Most blowouts in the analysed period occurred during drilling operations. Shallow gas blowouts were more frequent than deep blowouts and workover blowouts occurred more often than deep development drilling blowouts. Relatively few blowouts occurred during completion, wireline and normal production activities. No significant trend in blowout occurrences as a function of time could be observed, except for completion blowouts that showed a significantly decreasing trend. But there were trends regarding some important parameters for risk analyses, e.g. the ignition probability has decreased and diverter systems have improved. Only 3.5% of the fatalities occurred because of blowouts. 106 refs., 51 figs., 55 tabs.

  19. Fuel cell cooler-humidifier plate

    Science.gov (United States)

    Vitale, Nicholas G.; Jones, Daniel O.

    2000-01-01

    A cooler-humidifier plate for use in a proton exchange membrane (PEM) fuel cell stack assembly is provided. The cooler-humidifier plate combines functions of cooling and humidification within the fuel cell stack assembly, thereby providing a more compact structure, simpler manifolding, and reduced reject heat from the fuel cell. Coolant on the cooler side of the plate removes heat generated within the fuel cell assembly. Heat is also removed by the humidifier side of the plate for use in evaporating the humidification water. On the humidifier side of the plate, evaporating water humidifies reactant gas flowing over a moistened wick. After exiting the humidifier side of the plate, humidified reactant gas provides needed moisture to the proton exchange membranes used in the fuel cell stack assembly. The invention also provides a fuel cell plate that maximizes structural support within the fuel cell by ensuring that the ribs that form the boundaries of channels on one side of the plate have ends at locations that substantially correspond to the locations of ribs on the opposite side of the plate.

  20. Developing an Indicator System for Measuring the Social Sustainability of Offshore Wind Power Farms

    Directory of Open Access Journals (Sweden)

    Tzay-An Shiau

    2016-05-01

    Full Text Available Taiwan’s government has promoted investment in an offshore wind power farm, and local fishermen have protested. A social impact assessment (SIA has examined the impact of the proposed offshore wind power farm on all stakeholders. The main objective of the present study was to develop an indicator system for measuring the social sustainability of offshore wind power farms; this study also reports on the particular case of Taiwan’s offshore wind power project. This study began by defining 35 social sustainability indicators and selecting 23 representative indicators by using rough set theory. Subsequently, 14 key indicators were constructed using the social construction of technology (SCOT method. Finally, we developed a social impact index for evaluating the social sustainability of offshore wind power farms by using the analytic network process and Dempster-Shafer theory. Our social impact index yields a total score of 0.149 for Taiwan’s pilot offshore wind power project; this result indicates that the pilot project is socially sustainable. A substantial contradiction exists between the fishermen’s protest and the results of the social impact assessment. The findings can assist the government in building a coordination platform for the investors and the fishermen. Government regulation is necessary to set boundaries for fishing areas that protect both the fishermen’s and investors’ rights.

  1. Seismic swarms and fluid flow offshore Central America

    Science.gov (United States)

    Dzierma, Yvonne; Thorwart, Martin; Hensen, Christian; Rabbel, Wolfgang; Wolf, Florian

    2010-05-01

    Offshore Nicaragua and Northern Costa Rica, the Cocos Plate subducts beneath the Caribbean Plate, carrying with it a large amount of fluids and volatiles. While some of these are set free at great depth beneath the volcanic arc, causing the extremely high water content observed in Nicaraguan mafic magmas (Carr et al., 2003; Kutterolf et al., 2007), some early dehydration reactions already release fluids from the subducting plate underneath the continental slope. Unlike in accretionary margins, where these fluids migrate up along the decollement towards the deformation front, fluid release at erosional margins seems to occur through fractures in the overriding plate (Ranero et al., 2008). Fluid seeps in this region have be observed at seafloor mounds, appearing as side-scan sonar backscatter anomalies or revealed by the presence of chemosynthetic communities (Sahling et al., 2008). In the framework of the General Research Area SFB 574 "Volatiles and Fluids in Subduction Zones", a network of 20 ocean-bottom-stations was deployed offshore Sta Elena Peninsula, Northern Costa Rica, from December 2005 to June 2006. Several distinct swarms of small earthquakes were observed at the seismic stations, which occurred clustered over a time period of several days and have very similar seismic waveforms. Since a correlation of fluid-release sites with the occurrence of sporadic seismic swarms would indicate that fluid migration and fracturing is the mechanism responsible for triggering the earthquake swarms, the events are re-analysed by double-difference localisation to enhance the resolution of the earthquake locations. The results are then considered to estimate the migration velocity and direction and compare the localisations with the known mound sites. Carr, M., Feigenson, M. D., Patino, L. C., and Walker, J. A., 2003: Volcanism and geochemistry in Central America: Progress and problems, in Eiler, J. (ed.), Inside the subduction factory, pp. 153-179, American Geophysical

  2. A Real-Time Offshore Weather Risk Advisory System

    Science.gov (United States)

    Jolivet, Samuel; Zemskyy, Pavlo; Mynampati, Kalyan; Babovic, Vladan

    2015-04-01

    a 24 hour window of high resolution/accuracy forecasts leveraging available data-model integration and CAPE prediction. The systems includes dissemination of WRF outputs over the World Wide Web. Components of the system (including WRF computational engine and results dissemination modules) are deployed in to computational cloud. This approach tends to increase system robustness and sustainability. The creation of such a system to share information between the public and private sectors and across territorial boundaries is an important step towards the next generation of governance for climate risk and extreme weather offshore. The system benefits offshore operators by reducing downtime related to accidents and incidents; eliminate unnecessary hiring costs related to waiting on weather; and improve the efficiency and planning of transport and logistics by providing a rolling weather risk advisory.

  3. Chemical reaction in MHD flow past a vertical plate with mass ...

    African Journals Online (AJOL)

    flow in a vertical double passage channel using Robin boundary conditions. ... the diffusion of a chemically reactive species in a laminar boundary layer flow. ...... hydrodynamic flow past a flat plate will Hall effects, Journal of the Physical.

  4. Offshoring and Changes in Firms’ Domestic Employment

    DEFF Research Database (Denmark)

    Timmermans, Bram; Østergaard, Christian Richter

    difference on a set of employment characteristics, i.e. employment growth, growth in high skilled employees, and growth in employees with a background in science and engineering, by using a partial propensity score matching approach. The findings of the analyses show that there are clear differences between......In this paper, we investigate, by merging the Danish linked employer-employee database with a Danish offshoring survey, the difference in employment between offshoring and non-offshoring firms that are active in manufacturing industries and business services in Denmark. We measure the mean...... Danish offshoring and non-offshoring firms in how the employee composition changes over time. The change in employment composition differ considerably between manufacturing industries and business services and on whether firms offshore administrative and technical business functions or other types...

  5. Offshore Wind Power Planning in Korea

    DEFF Research Database (Denmark)

    Seo, Chul Soo; Cha, Seung-Tae; Park, Sang Ho

    2012-01-01

    this possible, Korea has announced the National offshore power roadmap and is now in pursuit. However, large scale offshore wind farms can incur many problems, such as power quality problems, when connecting to a power system.[1][2] Thus, KEPCO is on the process of a research study to evaluate the effects...... that connecting offshore wind power generation to a power system has on the power system. This paper looks over offshore wind power planning in Korea and describes the development of impact assessment technology of offshore wind farms.......Wind power generation is globally recognized as the most universal and reliable form of renewable energy. Korea is currently depending mostly on coal and petroleum to generate electrical power and is now trying to replace them with renewable energy such as offshore wind power generation. To make...

  6. Danish offshore wind - Key environmental issues

    International Nuclear Information System (INIS)

    2006-11-01

    Danish experience from the past 15 years shows that offshore wind farms, if placed right, can be engineered and operated without significant damage to the marine environment and vulnerable species. The comprehensive environmental monitoring programmes of Horns Rev Offshore Wind Farm and Nysted Offshore Wind Farm confirm that, under the rieght conditions, even big wind farms pose low risk to birds, mammals and fish, even though there will be changes in the living conditions of some species by an increase in habitat heterogeneity. The monitoring also shows that appropriate siting of offshore wind farms is an essential precondition for ensuring limited impact on nature and the environment, and that careful spatial planning is necessary to avoid damaging cumulative impacts. Due consideration to limiting the impacts on nature together with positive attitudes towards offshore wind farms in local communities and challenging energy policy objectives at national and international levels mean that prospects look bright for future offshore expansion. (au)

  7. Dutch offshore suppliers in confident mood

    International Nuclear Information System (INIS)

    Beudel, M.

    1998-01-01

    A series of linked articles discusses the current state of the Netherland's offshore industry. Reduced taxes, and availability of exploration licenses has meant that explorers and producers are drawn to the small size, but frequent yield explorations on Holland's continental shelf. The excellent operation record of Rotterdam's Verolme Botlek yard; for repair and maintenance of offshore platforms and associated plant, is explored as the facility plans to diversify into newbuilding. The construction of an offshore basin designed for the hydrodynamic testing of offshore plant intended for deepwater use is described. The Netherlands maritime research institute (Marin) aims to stay at the forefront of offshore research and development with this new facility. Other articles cover pipe tensioning, new large linear winches and innovations in offshore drilling and production. (UK)

  8. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    user

    International Journal of Engineering, Science and Technology .... dimensional MHD boundary layer on the body with time varying temperature. ... flow of an electrically conducting fluid past an infinite vertical porous flat plate coinciding with.

  9. The law of offshore petroleum development: basic concepts and main issues

    International Nuclear Information System (INIS)

    Carver, J.P.

    1994-01-01

    The problems associated with the delimitation of maritime areas, such as the continental shelf, are discussed with particular reference to offshore petroleum development. Methods of delimitation which have found favour are described. The principle of equidistance in delimiting the continental shelf between neighbouring states, whether opposite or adjacent is an example. Given the complexities of delimitation, acceptance of the need for agreement and that there is no definitive answer which will meet all the relevant circumstances is proposed as a starting point. How this works out is illustrated by the still hypothetical offshore international boundaries between Scotland and England. (UK)

  10. Three-Dimensional Wind Profiling of Offshore Wind Energy Areas With Airborne Doppler Lidar

    Science.gov (United States)

    Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

    2014-01-01

    A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-micrometer wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

  11. Offshore wind options for 2013; Offshore wind kansen voor 2013

    Energy Technology Data Exchange (ETDEWEB)

    Van der Meij-Kranendonk, J.

    2012-11-15

    In the USA researchers and companies are busy to the make knowledge and experiences gained elsewhere in the world suitable for the American market and to increase new knowledge in their own country. A brief overview is given of the activities in the US with regard to offshore wind energy [Dutch] Amerikaanse onderzoekers en bedrijven zijn druk bezig om de kennis en ervaring die opgedaan is elders in de wereld geschikt te maken voor de Amerikaanse markt en om nieuwe kennis op te doen in eigen land.

  12. Development of Offshore Wind Power Industry

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao

    2011-01-01

    The offshore wind power development target as initially proposed in "The 12=Five-Year" on energy recourses development and renewable energy recourses currently under development is to reach 5m KW by 2015 and 30m KW by 2020. With the unfolding of offshore wind turbine planning from different areas, the curtain of offshore wind power development for our country's "The 12=Five-Year" has been opened.

  13. The necessary distance between large wind farms offshore - study

    DEFF Research Database (Denmark)

    Frandsen, S.; Barthelmie, R.J.; Pryor, S.C.

    2005-01-01

    the new Storpark Analytical Model has been developed and evaluated. As it is often the need for offshore wind farms, the model handles a regular array-geometry with straight rows of wind turbines and equidistantspacing between units in each row and equidistant spacing between rows. Firstly, the case...... with the flow direction being parallel to rows in a rectangular geometry is considered by defining three flow regimes. Secondly, when the flow is not in line withthe main rows, solutions are found for the patterns of wind turbine units emerging corresponding to each wind direction. The model complex......A review of state of the art wake and boundary layer wind farms was conducted. The predictions made for wind recovery distances (that might be used to estimate optimal placing of neighbouring wind farms) range between 2 and 14 km. In order to model thelink between wakes and the boundary layer...

  14. Blurring Boundaries

    DEFF Research Database (Denmark)

    Neergaard, Ulla; Nielsen, Ruth

    2010-01-01

    of welfare functions into EU law both from an internal market law and a constitutional law perspective. The main problem areas covered by the Blurring Boundaries project were studied in sub-projects on: 1) Internal market law and welfare services; 2) Fundamental rights and non-discrimination law aspects......; and 3) Services of general interest. In the Blurring Boundaries project, three aspects of the European Social Model have been particularly highlighted: the constitutionalisation of the European Social Model, its multi-level legal character, and the clash between market access justice at EU level...... and distributive justice at national level....

  15. Boundary Spanning in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    imbalances of power, exacerbated in the case of an Indian vendor and a European client, need to be taken into account. The paper thus contributes with a more context sensitive understanding of inter-organizational boundary work. Taking the vendor perspective also leads to problematization of common...... of Indian IT vendor managers who are responsible for developing client relations and coordinating complex global development projects. The authors revise a framework of boundary spanning leadership practices to adapt it to an offshore outsourcing context. The empirical investigation highlights how...

  16. Attitude and acceptance of offshore wind farms

    DEFF Research Database (Denmark)

    Ladenburg, Jacob; Möller, B.

    2011-01-01

    farms attributes on attitude towards offshore wind farms. The results point towards that the travel time and the attributes of the nearest offshore wind farm influence the attitude significantly. Travel time has mixed effects on the attitude, whilst offshore wind farms with many turbines generate more...... a novel contribution to this field. First of all, we give a thorough review of the studies that have analysed the relation between experience with wind turbines and attitude. In addition, we supplement the review by analysing the effect of travel distance to the nearest offshore wind farm and the wind...

  17. Offshore Wind Energy Resource Assessment for Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Doubrawa Moreira, Paula [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scott, George N. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Musial, Walter D. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kilcher, Levi F. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Draxl, Caroline [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lantz, Eric J. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2018-01-02

    This report quantifies Alaska's offshore wind resource capacity while focusing on its unique nature. It is a supplement to the existing U.S. Offshore Wind Resource Assessment, which evaluated the offshore wind resource for all other U.S. states. Together, these reports provide the foundation for the nation's offshore wind value proposition. Both studies were developed by the National Renewable Energy Laboratory. The analysis presented herein represents the first quantitative evidence of the offshore wind energy potential of Alaska. The technical offshore wind resource area in Alaska is larger than the technical offshore resource area of all other coastal U.S. states combined. Despite the abundant wind resource available, significant challenges inhibit large-scale offshore wind deployment in Alaska, such as the remoteness of the resource, its distance from load centers, and the wealth of land available for onshore wind development. Throughout this report, the energy landscape of Alaska is reviewed and a resource assessment analysis is performed in terms of gross and technical offshore capacity and energy potential.

  18. DESIGN OF OFFSHORE CONCRETE GRAVITY PLATFORMS

    African Journals Online (AJOL)

    gas industry. Manufacturing and construction methods are discussed. Current ... Keywords: concrete gravity platform, offshore, foundation design, manufacturing, ... forms are used to support production drilling ... Manufacture and Construction.

  19. Preliminary study of the offshore wind and temperature profiles at the North of the Yucatan Peninsula

    International Nuclear Information System (INIS)

    Soler-Bientz, Rolando; Watson, Simon; Infield, David; Ricalde-Cab, Lifter

    2011-01-01

    Highlights: → This is the first study that reports the properties of the vertical wind resources for the offshore conditions of the North coast of the Yucatan Peninsula. → A significant and detailed analysis of the thermal patterns has revealed a complex structure of the atmospheric boundary layer close to the shore. → The structure of the diurnal wind patterns was assessed to produce an important reference for the wind resource availability in the study region. → It was identified that the sea breeze blows in directions almost parallel to the shoreline of the North of the Yucatan Peninsula during the majority of the 24 h cycle. → The analysis of the offshore data revealed a persistent non-uniform surface boundary layer developed as result of the advection of a warn air over a cold sea. - Abstract: The stability conditions in the atmospheric boundary layer, the intensity of the wind speeds and consequently the energy potential available in offshore conditions are highly influenced by the distance from the coastline and the differences between the air and sea temperatures. This paper presents a preliminary research undertook to study the offshore wind and temperature vertical profiles at the North-West of the Yucatan Peninsula coast. Ten minute averages were recorded over approximately 2 years from sensors installed at two different heights on a communication tower located at 6.65 km from the coastline. The results have shown that the offshore wind is thermally driven by differential heating of land and sea producing breeze patterns which veer to blow parallel to the coast under the action of the Coriolis force. To investigate further, a dataset of hourly sea surface temperatures derived from GEOS Satellite thermal maps was combined with the onsite measured data to study its effect on the vertical temperature profile. The results suggested largely unstable conditions and the potentially development of a shallow Stable Internal Boundary Layer which occurs

  20. Safety in offshore engineering an academic course covering safety in offshore wind

    NARCIS (Netherlands)

    Cerda Salzmann, D.J.

    2011-01-01

    Offshore projects are known for their challenging conditions, generally leading to high risks. Therefore no offshore project can go without a continuous and extensive assessment on safety issues. The Delft University of Technology is currently developing a course "Safety in Offshore Engineering"

  1. Tidal influence on offshore wind fields and resource predictions[Efficient Development of Offshore Windfarms

    Energy Technology Data Exchange (ETDEWEB)

    Khan, D. [Entec UK Ltd., Doherty Innovation Centre, Penicuik (United Kingdom); Infield, D. [Loughborough Univ., Centre for Renewable Energy Systems Tecnology, Loughborough (United Kingdom)

    2002-03-01

    The rise and fall of the sea surface due to tides effectively moves an offshore wind turbine hub through the wind shear profile. This effect is quantified using measured data from 3 offshore UK sites. Statistical evidence of the influence of tide on mean wind speed and turbulence is presented. The implications of this effect for predicting offshore wind resource are outlined. (au)

  2. Offshore system for integration of the wind energy; Sistema offshore para integracao de energia eolica

    Energy Technology Data Exchange (ETDEWEB)

    Decker, Jan de [3E, Brussels (Belgium); Tambke, Jens [Universidade de Oldemburg (Germany). ForWind; Voelker, J. [Dena - Agencia Alema de Energia (Germany); Michalowska-Knap, Katarzyna [Instituto de Energia Renovavel (Poland)

    2010-09-15

    The Offshore Grid project aims to analyze the conditions required for the development of an offshore transmission network to integrate renewable energy (wind) to the national electrical systems, securely and efficiently. Regulatory aspects, technical, economic and political are considered, that will help the various players in the industry to have a common view on the offshore power grids in Europe.

  3. Deformation of the Northwestern Okhotsk Plate: How is it happening?

    Science.gov (United States)

    Hindle, D.; Fujita, K.; Mackey, K.

    2009-09-01

    The Eurasia (EU) - North America (NA) plate boundary zone across Northeast Asia still presents many open questions within the plate tectonic paradigm. Constraining the geometry and number of plates or microplates present in the plate boundary zone is especially difficult because of the location of the EU-NA euler pole close to or even upon the EU-NA boundary. One of the major challenges remains the geometry of the Okhotsk plate (OK). whose northwestern portion terminates on the EU-OK-NA triple junction and is thus caught and compressed between converging EU and NA. We suggest that this leads to a coherent and understandable large scale deformation pattern of mostly northwest-southeast trending strike-slip faults which split Northwest OK into several extruding slivers. When the fault geometry is analysed together with space geodetic and focal mechanism data it suggests a central block which is extruding faster bordered east and west by progressively slower extruding blocks until the OK plate boundary faults are encountered. Taking into account elastic loading from both the intra-OK faults and the OK-Pacific (PA) boundary reconciles geodetic motions with geologic slip rates on at least the OK-NA boundary which corresponds to the Ulakhan fault.

  4. A folded plate clamped along one side only

    Science.gov (United States)

    Nazarov, Serguei A.; Slutskij, Andrey S.

    2017-12-01

    An asymptotic model of a folded thin elastic plate is posed on two plane domains and contains transmission conditions at the common line segment of their boundaries. These conditions become non-local and inhomogeneous if only one side of the plate is fixed. Solvability and smoothness results and error estimates for the model are derived. xml:lang="fr"

  5. Site selection for offshore wind farms along the Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    ManiMurali, R.; Vidya, P.J.; Modi, P.; JayaKumar, S.

    This study deals with locating the potential sites for offshore wind farms and also deals with feasibility of installing offshore wind farms through scientific examination of the requirements along the coast of India Offshore wind energy is almost...

  6. Theories for Elastic Plates via Orthogonal Polynomials

    DEFF Research Database (Denmark)

    Krenk, Steen

    1981-01-01

    A complementary energy functional is used to derive an infinite system of two-dimensional differential equations and appropriate boundary conditions for stresses and displacements in homogeneous anisotropic elastic plates. Stress boundary conditions are imposed on the faces a priori......, and this introduces a weight function in the variations of the transverse normal and shear stresses. As a result the coupling between the two-dimensional differential equations is described in terms of a single difference operator. Special attention is given to a truncated system of equations for bending...... of transversely isotropic plates. This theory has three boundary conditions, like Reissner's, but includes the effect of transverse normal strain, essentially through a reinterpretation of the transverse displacement function. Full agreement with general integrals to the homogeneous three-dimensional equations...

  7. Radiation shielding plate

    International Nuclear Information System (INIS)

    Kobayashi, Torakichi; Sugawara, Takeo.

    1983-01-01

    Purpose: To reduce the weight and stabilize the configuration of a radiation shielding plate which is used in close contact with an object to be irradiated with radiation rays. Constitution: The radiation shielding plate comprises a substrate made of lead glass and a metallic lead coating on the surface of the substrate by means of plating, vapor deposition or the like. Apertures for permeating radiation rays are formed to the radiation shielding plate. Since the shielding plate is based on a lead glass plate, a sufficient mechanical strength can be obtained with a thinner structure as compared with the conventional plate made of metallic lead. Accordingly, if the shielding plate is disposed on a soft object to be irradiated with radiation rays, the object and the plate itself less deform to obtain a radiation irradiation pattern with distinct edges. (Moriyama, K.)

  8. Natural frequency and vibration analysis of jacket type foundation for offshore wind power

    Science.gov (United States)

    Hung, Y.-C.; Chang, Y.-Y.; Chen, S.-Y.

    2017-12-01

    There are various types of foundation structure for offshore wind power, engineers may assess the condition of ocean at wind farm, and arrange the transportation, installation of each structure members, furthermore, considering the ability of manufacture steel structure as well, then make an optimum design. To design jacket offshore structure, unlike onshore cases, offshore structure also need to estimate the wave excitation effect. The aim of this paper is to study the difference of natural frequency between different kinds of structural stiffness and discuss the effect of different setting of boundary condition during analysis, besides, compare this value with the natural frequency of sea wave, in order to avoid the resonance effect. In this paper, the finite element analysis software ABAQUS is used to model and analyze the natural vibration behavior of the jacket structure.

  9. 31 CFR 543.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 543.406 Section 543.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... Interpretations § 543.406 Offshore transactions. The prohibitions in § 543.201 on transactions or dealings...

  10. 31 CFR 597.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 597.406 Section 597.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... REGULATIONS Interpretations § 597.406 Offshore transactions. The prohibitions contained in § 597.201 apply to...

  11. 31 CFR 544.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 544.406 Section 544.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... SANCTIONS REGULATIONS Interpretations § 544.406 Offshore transactions. The prohibitions in § 544.201 on...

  12. 31 CFR 593.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 593.406 Section 593.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... SANCTIONS REGULATIONS Interpretations § 593.406 Offshore transactions. The prohibitions in § 593.201 on...

  13. 31 CFR 547.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 547.406 Section 547.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... REGULATIONS Interpretations § 547.406 Offshore transactions. The prohibitions in § 547.201 on transactions or...

  14. 31 CFR 541.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 541.406 Section 541.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 541.406 Offshore transactions. The prohibitions in § 541.201 on transactions involving blocked...

  15. 31 CFR 548.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 548.406 Section 548.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 548.406 Offshore transactions. The prohibitions in § 548.201 on transactions or dealings involving...

  16. 31 CFR 537.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 537.406 Section 537.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 537.406 Offshore transactions. The prohibitions in § 537.201 on transactions involving blocked...

  17. 31 CFR 587.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 587.406 Section 587.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... MONTENEGRO) MILOSEVIC SANCTIONS REGULATIONS Interpretations § 587.406 Offshore transactions. The prohibitions...

  18. 31 CFR 546.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 546.406 Section 546.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 546.406 Offshore transactions. The prohibitions in § 546.201 on transactions or dealings involving...

  19. 31 CFR 542.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 542.406 Section 542.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... § 542.406 Offshore transactions. The prohibitions in § 542.201 on transactions involving blocked...

  20. 31 CFR 588.406 - Offshore transactions.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Offshore transactions. 588.406 Section 588.406 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... Interpretations § 588.406 Offshore transactions. The prohibitions in § 588.201 on transactions involving blocked...

  1. Offshore Vendors’ Software Development Team Configurations

    DEFF Research Database (Denmark)

    Chakraborty, Suranjan; Sarker, Saonee; Rai, Sudhanshu

    2012-01-01

    This research uses configuration theory and data collected from a major IT vendor organization to examine primary configurations of distributed teams in a global off-shoring context. The study indicates that off-shoring vendor organizations typically deploy three different types of configurations...

  2. A novel floating offshore wind turbine concept

    DEFF Research Database (Denmark)

    Vita, Luca; Schmidt Paulsen, Uwe; Friis Pedersen, Troels

    2009-01-01

    This paper will present a novel concept of a floating offshore wind turbine. The new concept is intended for vertical-axis wind turbine technology. The main purpose is to increase simplicity and to reduce total costs of an installed offshore wind farm. The concept is intended for deep water...... and large size turbines....

  3. Optimized power generation in offshore wind parks

    NARCIS (Netherlands)

    Oliveira Filho, J. de; Papp, Z.

    2011-01-01

    Electricity generation on offshore wind parks has an increasing economic importance - the European Commission foresees that 12% of the wind energy will be produced on offshore installations by 2020, and this share is likely to increase further in the following years. However, the continuously

  4. Whether or Not to Prepare for Offshoring

    DEFF Research Database (Denmark)

    Møller Larsen, Marcus; Geisler Asmussen, Christian; Pedersen, Torben

    2012-01-01

    A consequence of offshoring is increased coordination costs. To counter this, firms can strive to identify a cost reducing organizational configuration either ex ante or ex post to the offshoring implementation. In this paper, we investigate the performance implications of these contrasting strat...

  5. Reliability evaluation for offshore wind farms

    DEFF Research Database (Denmark)

    Zhao, Menghua; Blåbjerg, Frede; Chen, Zhe

    2005-01-01

    In this paper, a new reliability index - Loss Of Generation Ratio Probability (LOGRP) is proposed for evaluating the reliability of an electrical system for offshore wind farms, which emphasizes the design of wind farms rather than the adequacy for specific load demand. A practical method...... to calculate LOGRP of offshore wind farms is proposed and evaluated....

  6. A fair wind for the offshore

    International Nuclear Information System (INIS)

    Houot, G.

    2009-01-01

    The wind power future will take into account the sea. But to increase, the offshore channel must manage its organization and create a real cross-border cooperation. The author presents an economic analysis of the market with a special attention to the french sector. A map of the offshore sites in Europe is provided. (A.L.B.)

  7. Project alliancing in the offshore industry

    NARCIS (Netherlands)

    Halman, Johannes I.M.; Braks, B.F.M.

    In this paper the shift towards new types of project organisation within the Offshore Industry is explained and discussed. Special focus is given to the organisational concept of Project Alliancing. The principles, structure and culture of a Project Alliance as applied within the Offshore Industry

  8. Offshore Wind Market and Economic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, Bruce Duncan [Navigant Consulting, Inc., Chicago, IL (United States)

    2014-08-27

    This report is the third annual assessment of the U.S. offshore wind market. It includes the following major sections: Section 1: key data on developments in the offshore wind technology sector and the global development of offshore wind projects, with a particular focus on progress in the United States; Section 2: analysis of policy developments at the federal and state levels that have been effective in advancing offshore wind deployment in the United States; Section 3: analysis of actual and projected economic impact, including regional development and job creation; Section 4: analysis of developments in relevant sectors of the economy with the potential to affect offshore wind deployment in the United States

  9. Offshore wind resources at Danish measurement sites

    Energy Technology Data Exchange (ETDEWEB)

    Barthelmie, R J; Courtney, M S; Lange, B; Nielsen, M; Sempreviva, A M [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Svenson, J; Olsen, F [SEAS, Haslev (Denmark); Christensen, T [Elsamprojekt, Fredericia (Denmark)

    1999-03-01

    In order to characterise wind and turbulence characteristics at prospective offshore wind energy sites, meteorological observations from a number of purpose-built offshore monitoring sites have been analyzed and compared with long wind speed time series. New analyses have been conducted on the data sets focussing on meteorology, turbulence, extreme winds and wind and wave interactions. Relationships between wind speed, turbulence and fetch are highly complex. Minimum turbulence intensity offshore is associated with wind speeds of about 12 m/s. At lower wind speeds, stability effects are important while at higher winds speeds wind and wave interactions appear to dominate. On average, turbulence intensity offshore at 48 m height is approximately 0.08 if no coastal effects are present. However, the effect of the coastal discontinuity persists in wind speed and turbulence characteristics for considerable distances offshore. The majority of the adjustment of appears to occur within 20 km of the coast. (au)

  10. Design off-shore wind climate

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, G C; Joergensen, H E [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    Specific recommendations of off-shore turbulence intensities, applicable for design purposes, are lacking in the present IEC-code. The present off-shore wind climate analysis presents the distribution of the turbulence standard deviation around the mean turbulence standard deviation, conditioned on the mean wind speed. Measured distributions, based on a huge amount of measuring data from two shallow water off-shore sites, are parameterized by fitting to a three parameter Weibull distribution. Combining a simple heuristic load model with the parameterized probability density functions of the turbulence standard deviations, an empirical off-shore design turbulence intensity is evaluated that in average yields the same fatigue damage as the distributed turbulence intensity. The proposed off-shore design turbulence intensity is, within the IEC code framework, applicable for extreme as well as for fatigue load determination. (au)

  11. 2016 Offshore Wind Technologies Market Report

    Energy Technology Data Exchange (ETDEWEB)

    Musial, Walter; Beiter, Philipp; Schwabe, Paul; Tian, Tian; Stehly, Tyler; Spitsen, Paul; Robertson, Amy; Gevorgian, Vahan

    2017-08-08

    The 2016 Offshore Wind Technologies Market Report was developed by the National Renewable Energy Laboratory (NREL) for the U.S. Department of Energy (DOE) and is intended to provide offshore wind policymakers, regulators, developers, researchers, engineers, financiers, and supply chain participants, with quantitative information about the offshore wind market, technology, and cost trends in the United States and worldwide. In particular, this report is intended to provide detailed information on the domestic offshore wind industry to provide context to help navigate technical and market barriers and opportunities. The scope of the report covers the status of the 111 operating offshore wind projects in the global fleet through December 31, 2016, and provides the status and analysis on a broader pipeline of 593 projects at some stage of development. In addition, this report provides a wider assessment of domestic developments and events through the second quarter of 2017 to provide a more up-to-date discussion of this dynamically evolving industry.

  12. Buckling Response of Thick Functionally Graded Plates

    Directory of Open Access Journals (Sweden)

    BOUAZZA MOKHTAR

    2014-11-01

    Full Text Available In this paper, the buckling of a functionally graded plate is studied by using first order shear deformation theory (FSDT. The material properties of the plate are assumed to be graded continuously in the direction of thickness. The variation of the material properties follows a simple power-law distribution in terms of the volume fractions of constituents. The von Karman strains are used to construct the equilibrium equations of the plates subjected to two types of thermal loading, linear temperature rise and gradient through the thickness are considered. The governing equations are reduced to linear differential equation with boundary conditions yielding a simple solution procedure. In addition, the effects of temperature field, volume fraction distributions, and system geometric parameters are investigated. The results are compared with the results of the no shear deformation theory (classic plate theory, CPT.

  13. Theroretical modelling of the plate-tubes coupling in the hydroelasticity of the perforated plates

    International Nuclear Information System (INIS)

    Dzhupanov, V.A.; Manoach, E.S.

    1983-01-01

    In the previous investigations on the perforated plate hydroelasticity the problem of the plates-tubes-liquid interaction in the process of the general structural vibration is stated. But the interaction of the vibrating plates with the tubes, passing through them, is taken into account considering the tubes only as absolutely rigid supports. This is one of the possible technical realizations. In the present article the case when the tubes are taking part in the plate motion (vibration) is studied. Two circular perforated plates are supported by the absolutely rigid wall of the modelled roundcircular reactor barrel. The distance between the plates is given. They are connected by tubes, passing through, and clamped into the perforation holes. The plates and the tubes are made by any elastic HOOKIAN material. The volume between the two plates and outwardly to the tubes, but intrinsically of the barrel is filled by ideal, compressible and heavy liquid. Evidently the liquid volume is multiconnected one. The free vibration of the whole system is considered with the purposes: i) to give a theoretical model of the plates-tubes-liquid interaction including governing equations and boundary conditions; ii) to trace the solution of the eigen-value problem for the modelled structure; iii) to underline the engineering sides of the modelling process. (orig./GL)

  14. Numerical modeling of intraplate seismicity with a deformable loading plate

    Science.gov (United States)

    So, B. D.; Capitanio, F. A.

    2017-12-01

    We use finite element modeling to investigate on the stress loading-unloading cycles and earthquakes occurrence in the plate interiors, resulting from the interactions of tectonic plates along their boundary. We model a visco-elasto-plastic plate embedding a single or multiple faults, while the tectonic stress is applied along the plate boundary by an external loading visco-elastic plate, reproducing the tectonic setting of two interacting lithospheres. Because the two plates deform viscously, the timescale of stress accumulation and release on the faults is self-consistently determined, from the boundary to the interiors, and seismic recurrence is an emerging feature. This approach overcomes the constraints on recurrence period imposed by stress (stress-drop) and velocity boundary conditions, while here it is unconstrained. We illustrate emerging macroscopic characteristics of this system, showing that the seismic recurrence period τ becomes shorter as Γ and Θ decreases, where Γ = ηI/ηL the viscosity ratio of the viscosities of the internal fault-embedded to external loading plates, respectively, and Θ = σY/σL the stress ratio of the elastic limit of the fault to far-field loading stress. When the system embeds multiple, randomly distributed faults, stress transfer results in recurrence period deviations, however the time-averaged recurrence period of each fault show the same dependence on Γ and Θ, illustrating a characteristic collective behavior. The control of these parameters prevails even when initial pre-stress was randomly assigned in terms of the spatial arrangement and orientation on the internal plate, mimicking local fluctuations. Our study shows the relevance of macroscopic rheological properties of tectonic plates on the earthquake occurrence in plate interiors, as opposed to local factors, proposing a viable model for the seismic behavior of continent interiors in the context of large-scale, long-term deformation of interacting tectonic

  15. Mean flow structure of non-equilibrium boundary layers with adverse ...

    Indian Academy of Sciences (India)

    According to them, an equilibrium boundary layer might exist if the pressure ... of adverse pressure gradient on the turbulent boundary layer at the flat plate for ..... of a constant-pressure turbulent layer to the sudden application of an sudden.

  16. Create Your Plate

    Medline Plus

    Full Text Available ... foods you want, but changes the portion sizes so you are getting larger portions of non-starchy ... plate. Then on one side, cut it again so you will have three sections on your plate. ...

  17. Create Your Plate

    Medline Plus

    Full Text Available ... of the differences in types of vegetables. When creating your plate at home, remember that half of ... effective for both managing diabetes and losing weight. Creating your plate lets you still choose the foods ...

  18. Create Your Plate

    Medline Plus

    Full Text Available ... Index Low-Calorie Sweeteners Sugar and Desserts Fitness Exercise & Type 1 Diabetes Get Started Safely Get And ... Plate Create Your Plate is a simple and effective way to manage your blood glucose levels and ...

  19. Create Your Plate

    Medline Plus

    Full Text Available ... Meals Diabetes Meal Plans Create Your Plate Gluten Free Diets Meal Planning for Vegetarian Diets Cook with ... Your Plate Meal Planning for Vegetarian Diets Gluten Free Diets Holiday Meal Planning Cook with Heart-Healthy ...

  20. Create Your Plate

    Medline Plus

    Full Text Available ... Your Plate Gluten Free Diets Meal Planning for Vegetarian Diets Cook with Heart-Healthy Foods Holiday Meal ... Healthy Diet Create Your Plate Meal Planning for Vegetarian Diets Gluten Free Diets Holiday Meal Planning Cook ...

  1. On the vibrations of a simply supported square plate on a weakly nonlinear elastic foundation

    NARCIS (Netherlands)

    Zarubinskaya, M.A.; Van Horssen, W.T.

    2003-01-01

    In this paper an initial-boundary value problem for a weakly nonlinear plate equation with a quadratic nonlinearity will be studied. This initial-boundary value problem can be regarded as a simple model describing free oscillations of a simply supported square plate on an elastic foundation. It is

  2. Sound Radiation of Aerodynamically Excited Flat Plates into Cavities

    Directory of Open Access Journals (Sweden)

    Johannes Osterziel

    2017-10-01

    Full Text Available Flow-induced vibrations and the sound radiation of flexible plate structures of different thickness mounted in a rigid plate are experimentally investigated. Therefore, flow properties and turbulent boundary layer parameters are determined through measurements with a hot-wire anemometer in an aeroacoustic wind tunnel. Furthermore, the excitation of the vibrating plate is examined by laser scanning vibrometry. To describe the sound radiation and the sound transmission of the flexible aluminium plates into cavities, a cuboid-shaped room with adjustable volume and 34 flush-mounted microphones is installed at the non flow-excited side of the aluminium plates. Results showed that the sound field inside the cavity is on the one hand dependent on the flow parameters and the plate thickness and on the other hand on the cavity volume which indirectly influences the level and the distribution of the sound pressure behind the flexible plate through different excited modes.

  3. High precision refractometry based on Fresnel diffraction from phase plates.

    Science.gov (United States)

    Tavassoly, M Taghi; Naraghi, Roxana Rezvani; Nahal, Arashmid; Hassani, Khosrow

    2012-05-01

    When a transparent plane-parallel plate is illuminated at a boundary region by a monochromatic parallel beam of light, Fresnel diffraction occurs because of the abrupt change in phase imposed by the finite change in refractive index at the plate boundary. The visibility of the diffraction fringes varies periodically with changes in incident angle. The visibility period depends on the plate thickness and the refractive indices of the plate and the surrounding medium. Plotting the phase change versus incident angle or counting the visibility repetition in an incident-angle interval provides, for a given plate thickness, the refractive index of the plate very accurately. It is shown here that the refractive index of a plate can be determined without knowing the plate thickness. Therefore, the technique can be utilized for measuring plate thickness with high precision. In addition, by installing a plate with known refractive index in a rectangular cell filled with a liquid and following the described procedures, the refractive index of the liquid is obtained. The technique is applied to measure the refractive indices of a glass slide, distilled water, and ethanol. The potential and merits of the technique are also discussed.

  4. Modeling long period swell in Southern California: Practical boundary conditions from buoy observations and global wave model predictions

    Science.gov (United States)

    Crosby, S. C.; O'Reilly, W. C.; Guza, R. T.

    2016-02-01

    Accurate, unbiased, high-resolution (in space and time) nearshore wave predictions are needed to drive models of beach erosion, coastal flooding, and alongshore transport of sediment, biota and pollutants. On highly sheltered shorelines, wave predictions are sensitive to the directions of onshore propagating waves, and nearshore model prediction error is often dominated by uncertainty in offshore boundary conditions. Offshore islands and shoals, and coastline curvature, create complex sheltering patterns over the 250km span of southern California (SC) shoreline. Here, regional wave model skill in SC was compared for different offshore boundary conditions created using offshore buoy observations and global wave model hindcasts (National Oceanographic and Atmospheric Administration Wave Watch 3, WW3). Spectral ray-tracing methods were used to transform incident offshore swell (0.04-0.09Hz) energy at high directional resolution (1-deg). Model skill is assessed for predictions (wave height, direction, and alongshore radiation stress) at 16 nearshore buoy sites between 2000 and 2009. Model skill using buoy-derived boundary conditions is higher than with WW3-derived boundary conditions. Buoy-driven nearshore model results are similar with various assumptions about the true offshore directional distribution (maximum entropy, Bayesian direct, and 2nd derivative smoothness). Two methods combining offshore buoy observations with WW3 predictions in the offshore boundary condition did not improve nearshore skill above buoy-only methods. A case example at Oceanside harbor shows strong sensitivity of alongshore sediment transport predictions to different offshore boundary conditions. Despite this uncertainty in alongshore transport magnitude, alongshore gradients in transport (e.g. the location of model accretion and erosion zones) are determined by the local bathymetry, and are similar for all predictions.

  5. Offshore Aquaculture Development in Ecuador

    Directory of Open Access Journals (Sweden)

    Julio López Alvarado

    2016-03-01

    Full Text Available Ecuador has a long tradition in aquaculture, mainly related to the cultivation of shrimp and tilapia in earthen ponds. Land-based production methods have a large environmental, economic and social impact due to the extensive use of land and its effects on the ecosystems. In order to increase the production of fish without further land use and with a lower environmental impact, a good alternative is the culture of fish in floating cages, adopting technologies used successfully in many other countries. This article analyses the current situation of offshore aquaculture (the production of fish and other aquatic organisms in the open sea in Ecuador, and the prospects for the future of this sector in the country.

  6. Image processing in offshore engineering

    International Nuclear Information System (INIS)

    Rodriguez, M.V.R.; A. Oliveira, M. de; Almeida, M.E.T. de; Lorenzoni, C.; Ferrante, A.J.

    1995-01-01

    The technological progress which has taken place during the last decade introduced a totally new outlook regarding the professional computational environment in general, and regarding the engineering profession in particular. During many years engineering computing was performed based on large computer centers, getting bigger and bigger all the time, going from mainframes to super computers, essentially producing numerical results on paper media. Lately, however, it has been realized that a much more productive computational environment can be implemented using an open architecture of client/server type, based on smaller lower cost equipment including workstations and PC's, and considering engineering information in a broader sense. This papers reports briefly the experience of the Production Department of Petrobras in transforming its centralized, mainframe based, computational environment into a open distributed client/server computational environment, focusing on the problem of handling technical graphics information regarding its more than 70 fixed offshore platforms

  7. Boundary issues

    Science.gov (United States)

    Townsend, Alan R.; Porder, Stephen

    2011-03-01

    What is our point of no return? Caesar proclaimed 'the die is cast' while crossing the Rubicon, but rarely does modern society find so visible a threshold in our continued degradation of ecosystems and the services they provide. Humans have always used their surroundings to make a living— sometimes successfully, sometimes not (Diamond 2005)—and we intuitively know that there are boundaries to our exploitation. But defining these boundaries has been a challenge since Malthus first prophesied that nature would limit the human population (Malthus 1798). In 2009, Rockström and colleagues tried to quantify what the 6.8 billion (and counting) of us could continue to get away with, and what we couldn't (Rockström et al 2009). In selecting ten 'planetary boundaries', the authors contend that a sustainable human enterprise requires treating a number of environmental thresholds as points of no return. They suggest we breach these Rubicons at our own peril, and that we've already crossed three: biodiversity loss, atmospheric CO2, and disruption of the global nitrogen (N) cycle. As they clearly hoped, the very act of setting targets has provoked scientific inquiry about their accuracy, and about the value of hard targets in the first place (Schlesinger 2009). Such debate is a good thing. Despite recent emphasis on the science of human-ecosystem interactions, understanding of our planetary boundaries is still in its infancy, and controversy can speed scientific progress (Engelhardt and Caplan 1987). A few weeks ago in this journal, Carpenter and Bennett (2011) took aim at one of the more controversial boundaries in the Rockström analysis: that for human alteration of the global phosphorus (P) cycle. Rockström's group chose riverine P export as the key indicator, suggesting that humans should not exceed a value that could trigger widespread marine anoxic events—and asserting that we have not yet crossed this threshold. There are defensible reasons for a marine

  8. boundary dissipation

    Directory of Open Access Journals (Sweden)

    Mehmet Camurdan

    1998-01-01

    are coupled by appropriate trace operators. This overall model differs from those previously studied in the literature in that the elastic chamber floor is here more realistically modeled by a hyperbolic Kirchoff equation, rather than by a parabolic Euler-Bernoulli equation with Kelvin-Voight structural damping, as in past literature. Thus, the hyperbolic/parabolic coupled system of past literature is replaced here by a hyperbolic/hyperbolic coupled model. The main result of this paper is a uniform stabilization of the coupled PDE system by a (physically appealing boundary dissipation.

  9. Offshore Wind Energy Systems Engineering Curriculum Development

    Energy Technology Data Exchange (ETDEWEB)

    McGowan, Jon G. [Univ. of Massachusetts, Amherst, MA (United States); Manwell, James F. [Univ. of Massachusetts, Amherst, MA (United States); Lackner, Matthew A. [Univ. of Massachusetts, Amherst, MA (United States)

    2012-12-31

    Utility-scale electricity produced from offshore wind farms has the potential to contribute significantly to the energy production of the United States. In order for the U.S. to rapidly develop these abundant resources, knowledgeable scientists and engineers with sound understanding of offshore wind energy systems are critical. This report summarizes the development of an upper-level engineering course in "Offshore Wind Energy Systems Engineering." This course is designed to provide students with a comprehensive knowledge of both the technical challenges of offshore wind energy and the practical regulatory, permitting, and planning aspects of developing offshore wind farms in the U.S. This course was offered on a pilot basis in 2011 at the University of Massachusetts and the National Renewable Energy Laboratory (NREL), TU Delft, and GL Garrad Hassan have reviewed its content. As summarized in this report, the course consists of 17 separate topic areas emphasizing appropriate engineering fundamentals as well as development, planning, and regulatory issues. In addition to the course summary, the report gives the details of a public Internet site where references and related course material can be obtained. This course will fill a pressing need for the education and training of the U.S. workforce in this critically important area. Fundamentally, this course will be unique due to two attributes: an emphasis on the engineering and technical aspects of offshore wind energy systems, and a focus on offshore wind energy issues specific to the United States.

  10. Offshore Fish Community: Ecological Interactions | Science ...

    Science.gov (United States)

    The offshore (>80 m) fish community of Lake Superior is made up of predominately native species. The most prominent species are deepwater sculpin, kiyi, cisco, siscowet lake trout, burbot, and the exotic sea lamprey. Bloater and shortjaw cisco are also found in the offshore zone. Bloater is abundant in the offshore zone but appears restricted to depths shallower than 150 m (Selgeby and Hoff 1996; Stockwell et al. 2010), although it occuppied greater depths several decades ago (Dryer 1966; Peck 1977). Shortjaw is relatively rare in the offshore zone (Hoff and Todd 2004; Gorman and Hoff 2009; Gorman and Todd 2007). Lake whitefish is also known to frequent bathymetric depths >100 m (Yule et al. 2008b). In this chapter, we develop a conceptual model of the offshore food web based on data collected during 2001-2005 and on inferences from species interactions known for the nearshore fish community. We then develop a framework for examination of energy and nutrient movements within the pelagic and benthic habitats of the offshore zone and across the offshore and nearshore zones. To document research results.

  11. Sensitivity analysis of floating offshore wind farms

    International Nuclear Information System (INIS)

    Castro-Santos, Laura; Diaz-Casas, Vicente

    2015-01-01

    Highlights: • Develop a sensitivity analysis of a floating offshore wind farm. • Influence on the life-cycle costs involved in a floating offshore wind farm. • Influence on IRR, NPV, pay-back period, LCOE and cost of power. • Important variables: distance, wind resource, electric tariff, etc. • It helps to investors to take decisions in the future. - Abstract: The future of offshore wind energy will be in deep waters. In this context, the main objective of the present paper is to develop a sensitivity analysis of a floating offshore wind farm. It will show how much the output variables can vary when the input variables are changing. For this purpose two different scenarios will be taken into account: the life-cycle costs involved in a floating offshore wind farm (cost of conception and definition, cost of design and development, cost of manufacturing, cost of installation, cost of exploitation and cost of dismantling) and the most important economic indexes in terms of economic feasibility of a floating offshore wind farm (internal rate of return, net present value, discounted pay-back period, levelized cost of energy and cost of power). Results indicate that the most important variables in economic terms are the number of wind turbines and the distance from farm to shore in the costs’ scenario, and the wind scale parameter and the electric tariff for the economic indexes. This study will help investors to take into account these variables in the development of floating offshore wind farms in the future

  12. Understanding public responses to offshore wind power

    International Nuclear Information System (INIS)

    Haggett, Claire

    2011-01-01

    This paper is about understanding the role and importance of public responses to offshore wind power. It builds on a framework for understanding social acceptance and opposition to onshore turbines, and reviews the emerging research on offshore wind. While less is known about how people will respond to offshore than onshore wind, there is now an emerging body of research. From this literature, several common factors which influence responses have emerged and are discussed here: the (continued) role of visual impact; place attachment to the local area; lack of tangible benefits; relationships with developers and outsiders; and the role of the planning and decision-making systems. The paper argues that, as with onshore developments, the public should be included in decision-making about offshore wind farms, and that they have a key role which should not be underestimated. The paper concludes with some thoughts about the means to involve people and how effected communities might be effectively acknowledged, identified and engaged. - Research Highlights: →Comprehensive review of public responses to offshore wind literature. →Applies key lessons and analytic insights from onshore wind to offshore wind. →Emphasizes the role and importance of the public in the planning and implementation of offshore wind energy.

  13. NREL Offshore Balance-of-System Model

    Energy Technology Data Exchange (ETDEWEB)

    Maness, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States); Maples, Benjamin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Smith, Aaron [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-01-01

    The U.S. Department of Energy (DOE) has investigated the potential for 20% of nationwide electricity demand to be generated from wind by 2030 and, more recently, 35% by 2050. Achieving this level of wind power generation may require the development and deployment of offshore wind technologies. DOE (2008) has indicated that reaching these 2030 and 2050 scenarios could result in approximately 10% and 20%, respectively, of wind energy generation to come from offshore resources. By the end of 2013, 6.5 gigawatts of offshore wind were installed globally. The first U.S. project, the Block Island Wind Farm off the coast of Rhode Island, has recently begun operations. One of the major reasons that offshore wind development in the United States is lagging behind global trends is the high capital expenditures required. An understanding of the costs and associated drivers of building a commercial-scale offshore wind plant in the United States will inform future research and help U.S. investors feel more confident in offshore wind development. In an effort to explain these costs, the National Renewable Energy Laboratory has developed the Offshore Balance-of-System model.

  14. Offshoring in the Semiconductor Industry: Historical Perspectives

    OpenAIRE

    Brown, Clair; Linden, Greg

    2005-01-01

    Semiconductor design is a frequently-cited example of the new wave of offshoring and foreign-outsourcing of service sector jobs. It is certainly a concern to U.S. design engineers themselves. In addition to the current wave of white-collar outsourcing, the industry also has a rich experience with offshoring of manufacturing activity. Semiconductor companies were among the first to invest in offshore facilities to manufacture goods for imports back to the U.S. A brief review of these earlie...

  15. The environmental impact from an offshore plant

    International Nuclear Information System (INIS)

    Larsson, A.-K.

    1994-01-01

    Wind measurements in different countries have shown the existence of a large energy potential in offshore winds. Taking into consideration the limited suitable area on land for wind power plants it is essential to know the environmental influence from and on an offshore plant. The first offshore wind power plant was built in Sweden in 1990 in order to examine the influence on birds, fish and fishing, shipping, public opinion, maintenance and the effects on foundation from waves and ice. So far, the programme shows that the birds try to avoid the plant by flying further away from it out over the sea. (Author)

  16. Operation and maintenance of offshore wind farms

    DEFF Research Database (Denmark)

    Petersen, Kristian R.; Madsen, Erik Skov; Bilberg, Arne

    The offshore wind industry is booming and larger, more efficient wind-turbines have constantly been introduced into the market. However, research within the field of the operation and maintenance (O&M) of offshore wind farms is limited as the field is still immature. In this paper, two current ma...... maintenance models - RCM and TPM - are discussed in this context. Furthermore, through a case study, the paper looks into Modularization and SSLP, as these concepts can be utilized to optimize maintenance. This is a new approach for the offshore wind industry....

  17. The offshorization of economy: the present realities

    OpenAIRE

    Maslak Olga; Grishko Natalya; Hlazunova Olha; Vorobiova Kateryna

    2017-01-01

    In this article the essence and main types of offshore zones have been studied. It has been analyzed the main reasons for cooperation with the tax havens, established that the main reason of the Ukrainian economy offshorization is not only the desire of economic entities to optimize taxes, but also the desire to protect their assets from the negative impact of the crisis phenomena in the national economy during 2010-2016. The foreign experience of the anti-offshore regulation has been researc...

  18. Offshore wind market outlook in Northern Europe

    Energy Technology Data Exchange (ETDEWEB)

    Pimenta de Miranda, Wilfried; Trulsson, Ola; Ekloef, Eva-Britt; Niemenen, Karel

    2010-08-15

    After more than 10 years of slow developments, the offshore wind market is now accelerating. Thanks to a sustained political drive from UK and Germany, the rest of Northern Europe is now following the path as offshore wind is being recognized as one of the key resources available to the EU to meet its renewable energy ambitions. Exposed to increasing technical issues, rising costs and the financial crisis, lessons learned are now being shared and integrated throughout Europe and appropriate regulatory and planning reforms are now being deployed to speed the deployment of offshore wind. (Author)

  19. Paper microzone plates.

    Science.gov (United States)

    Carrilho, Emanuel; Phillips, Scott T; Vella, Sarah J; Martinez, Andres W; Whitesides, George M

    2009-08-01

    This paper describes 96- and 384-microzone plates fabricated in paper as alternatives to conventional multiwell plates fabricated in molded polymers. Paper-based plates are functionally related to plastic well plates, but they offer new capabilities. For example, paper-microzone plates are thin (approximately 180 microm), require small volumes of sample (5 microL per zone), and can be manufactured from inexpensive materials ($0.05 per plate). The paper-based plates are fabricated by patterning sheets of paper, using photolithography, into hydrophilic zones surrounded by hydrophobic polymeric barriers. This photolithography used an inexpensive formulation photoresist that allows rapid (approximately 15 min) prototyping of paper-based plates. These plates are compatible with conventional microplate readers for quantitative absorbance and fluorescence measurements. The limit of detection per zone loaded for fluorescence was 125 fmol for fluorescein isothiocyanate-labeled bovine serum albumin, and this level corresponds to 0.02 the quantity of analyte per well used to achieve comparable signal-to-noise in a 96-well plastic plate (using a solution of 25 nM labeled protein). The limits of detection for absorbance on paper was approximately 50 pmol per zone for both Coomassie Brilliant Blue and Amaranth dyes; these values were 0.4 that required for the plastic plate. Demonstration of quantitative colorimetric correlations using a scanner or camera to image the zones and to measure the intensity of color, makes it possible to conduct assays without a microplate reader.

  20. Seafloor spreading on the Southeast Indian Ridge over the last one million years: a test of the Capricorn plate hypothesis

    Science.gov (United States)

    Conder, James A.; Forsyth, Donald W.

    2001-05-01

    Plate motions in the Indian Ocean are inconsistent with a rigid Indo-Australian plate. An equatorial, diffuse boundary dividing the plate into separate Indian and Australian plates significantly improves the fit of kinematic plate models to the spreading rates, transform azimuths, and earthquake slip vectors on the spreading center boundaries. An additional boundary, further dividing the Australian plate into Australian and Capricorn plates has been proposed to account for much of the remaining inconsistency and the pattern of intraplate earthquakes [J.-Y. Royer, R.G. Gordon, Science 277 (1997) 1268-1274]. The proposed boundary is ˜2000 km wide where it intersects the Southeast Indian Ridge. Several recent geophysical cruises to the Southeast Indian Ridge, including a cruise within the proposed boundary, provide many new data for investigating the validity of the Capricorn plate model. These new observations strongly support the hypothesis that the Capricorn plate exists. Statistical tests of the data from the Southeast Indian Ridge alone are not sufficient to confirm it, but motion about the Rodriguez Triple Junction (RTJ) suggests some non-rigidity in the Antarctica-Australia-Somalia circuit. Inferred deformation with enforced closure about the RTJ leads to an estimate of plate motion consistent with the Capricorn plate model. However, the diffuse Capricorn-Australia boundary does not extend south of the St. Paul Fracture Zone, 800 km narrower than the previously proposed boundary.

  1. Observations of offshore bar decay

    DEFF Research Database (Denmark)

    Aagaard, Troels; Kroon, Aart; Greenwood, Brian

    2010-01-01

    the upper shoreface, and finally a stage of decaying bar form through loss of sediment volume at the outer boundary of the upper shoreface. The phenomenon has been previously documented in the Netherlands, the USA, the Canadian Great Lakes, and in New Zealand, but our present understanding...

  2. Boundary-layer effects on cold fronts at a coastline

    Science.gov (United States)

    Garratt, J. R.

    1986-07-01

    The present note discusses one physical mechanism which may contribute to cold air channelling, manifest as a frontal bulge on a surface-analysis chart, in the coastal region of Victoria in southeast Australia. This involves the modification of boundary-layer air in both offshore (prefrontal) and onshore (postfrontal) flow, and the effect on cross-frontal thermal contrast. The problem is discussed in terms of a north-south-oriented cold front behaving as an atmospheric gravity current, propagating along an east-west-oriented coastline, in the presence of a prefrontal offshore stream.

  3. Offshore investments-cui prodis? Schrodinger's cat in offshore financing: Both alive and dead

    Directory of Open Access Journals (Sweden)

    Stepuk Anna

    2014-01-01

    Full Text Available Trends of FDI in offshore tax havens were compared to efforts and efficiency of regulatory authorities to prevent money laundering. Based on available data it was stated that current position in offshore FDI stays alive and officially dead at the same time, keeping the balance of interests for the main stakeholders: corporations, authorities and financial institutes support further offshore investments. Analysis based on volumes of trade and financial transactions between offshore centers, developed and developing countries. As a result withdrawal of financial resources from the developing countries degrades social capital funding and supports corruption growth.

  4. Capability Development in an Offshoring Context

    DEFF Research Database (Denmark)

    Jaura, Manya

    Capability development can be defined as deliberate firm-level investment involving a search and learning process aimed at modifying or enhancing existing capabilities. Increasingly, firms are relocating advanced services to offshore locations resulting in the challenge of capability development ...

  5. DOD Offshore Wind Mission Compatibility Assessments

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the results of analyses conducted by the Department of Defense to assess the compatibility of offshore wind development with military assets...

  6. CRSMP Potential Offshore Borrow Sites 2012

    Data.gov (United States)

    California Natural Resource Agency — Offshore borrow sites as identified originally in the California Shoreline Database compiled by Noble Consultants (Jon Moore). Later updates to the dataset by the...

  7. Viewing engineering offshoring in a network perspective

    DEFF Research Database (Denmark)

    Hansen, Zaza Nadja Lee; Zhang, Yufeng; Ahmed-Kristensen, Saeema

    2013-01-01

    of how to effectively manage engineering offshoring activities in a context of global engineering networks. The main research question, therefore, is: “Can offshoring of engineering tasks be explained and managed using the concept of Global Engineering Networks (GEN)?” Effective approaches to handling...... of large multinational corporations in Denmark were carried out. Data gathering was mainly documentary studies and interviews. The main data analysis approaches were coding (Strauss and Corbin) and pattern-matching (Yin). The dataset was analysed using the GEN framework suggested by Zhang et al. and Zhang...... by extending the GEN framework to address complications within engineering offshoring. This strengthens both academic fields, and will be able to help engineering managers to develop appropriate engineering network configurations for offshore engineering operations....

  8. Environmental risk in the offshore industry

    International Nuclear Information System (INIS)

    Woods, I.T.; Shirley, D.; Bottelberghs, P.H.

    1991-01-01

    The subject of oil pollution of the sea by the offshore industry is topical as a result of recent incidents both in the U.K. and overseas. While these incidents have primarily involved crude carriers, it has led to pressure to quantify the risk to the environment from the offshore industry in general. In this paper a method for the assessment of the frequency and size of oil spills from offshore installations is presented. It relies on previously reported spills to determine spill size/frequency information for a range of offshore activities, such as transport by pipeline, drilling and processing. Modification factors are used so local conditions, such as the number of wells drilled, throughput and well depth, can be considered in the assessment of the oil spill risk from a particular installation

  9. Dynamic analysis and design of offshore structures

    CERN Document Server

    Chandrasekaran, Srinivasan

    2015-01-01

    This book  attempts to provide readers with an overall idea of various types of offshore platform geometries. It covers the various environmental loads encountered by these structures, a detailed description of the fundamentals of structural dynamics in a class-room style, estimate of damping in offshore structures and their applications in the preliminary analysis and design. Basic concepts of structural dynamics are emphasized through simple illustrative examples and exercises. Design methodologies and guidelines, which are FORM based concepts are explained through a few applied example structures. Each chapter also has tutorials and exercises for self-learning. A dedicated chapter on stochastic dynamics will help the students to extend the basic concepts of structural dynamics to this advanced domain of research. Hydrodynamic response of offshore structures with perforated members is one of the recent research applications, which is found to be one of the effective manner of retrofitting offshore structur...

  10. Switching overvoltages in offshore wind power grids

    DEFF Research Database (Denmark)

    Arana Aristi, Ivan

    and cables are presented. In Chapter 4 results from time domain measurements and simulations of switching operations in offshore wind power grids are described. Specifically, switching operations on a single wind turbine, the collection grid, the export system and the external grid measured in several real...... offshore wind farms are shown together with simulation results. Switching operations in offshore wind power grids can be simulated with different electromagnetic transient programs. Different programs were used in the project and compared results are included in Chapter 4. Also in Chapter 4 different......Switching transients in wind turbines, the collection grid, the export system and the external grid in offshore wind farms, during normal or abnormal operation, are the most important phenomena when conducting insulation coordination studies. However, the recommended models and methods from...

  11. Second wind in the offshore wind industry

    International Nuclear Information System (INIS)

    Philippe, Edouard; Neyme, Eric; Deboos, Christophe; Villageois, Jean-Remy; Gouverneur, Philippe; Gerard, Bernard; Fournier, Eric; Petrus, Raymond; Lemarquis, David; Dener, Marc; Bivaud, Jean-Pierre; Lemaire, Etienne; Nielsen, Steffen; Lafon, Xavier; Lagandre, Pierre; Nadai, Alain; Pinot de Villechenon, Edouard; Westhues, Markus; Herpers, Frederick; Bisiaux, Christophe; Sperlich, Miriam; Bales, Vincent; Vandenbroeck, Jan; His, Stephane; Derrey, Thierry; Barakat, Georges; Dakyo, Brayima; Carme, Laurent; Petit, Frederic; Ytournel, Sophie; Westhues, Markus; Diller, Armin; Premont, Antoine de; Ruer, Jacques; Lanoe, Frederic; Declercq, Jan; Holmager, Morten; Fidelin, Daniel; Guillet, Jerome; Dudziak, Gregory; Lapierre, Anne; Couturier, Ludovic; Audineau, Jean-Pierre; Rouaix, Eric; De Roeck, Yann-Herve; Quesnel, Louis; Duguet, Benjamin

    2011-06-01

    After several keynote addresses, this publication contains contributions and Power Point presentations proposed during this conference on the development of offshore wind energy. The successive sessions addressed the following issues: the offshore mass production of electricity (examples of Denmark and Belgium, laying and protecting offshore cables), the space, economic and environmental planning (the Danish experience, the role of the Coastal area integrated management, importance of the public debate, so on), the logistics of port infrastructures (simulation tools, example of Bremerhaven, issues related to project management), innovation at the core of industrial strategies (high power wind turbines, the 6 MW Alstom turbine, chain value and innovation in offshore wind energy, the Vertiwing innovating project of a floating wind turbine, a bench test in Charleston, foundations, gravity base structures, the British experience, the Danish experience), the economic and organisational conditions for development, the validation and certification of technologies

  12. Offshore wind development research (technical brief).

    Science.gov (United States)

    2014-04-01

    The study addresses all aspects of Offshore Wind (OSW) development. This includes identifying : vessel types, vessel installation methods, needs and operating characteristics through all phases : of OSW installation, construction, operations and main...

  13. Longitudinal vortices in a transitioning boundary layer

    International Nuclear Information System (INIS)

    Anders, J.B.; Backwelder, R.F.

    1980-01-01

    Naturally occurring spanwise variations of the streamwise velocity component, characteristic of longitudinal vortices embedded in a transitioning boundary layer were explored using hot-wire anemometers. A vibrating ribbon introduced stable or unstable Tollmien-Schlichting waves into the laminar boundary layer. These damped or growing disturbances always developed a strong three-dimensional pattern even though no spanwise perturbations were artificially induced. Changing the radius of the leading edge and other modifications to the flat plate, wind tunnel and boundary layer did not alter the spanwise wavelength of the vortices. (orig.)

  14. The onshore influence of offshore fresh groundwater

    Science.gov (United States)

    Knight, Andrew C.; Werner, Adrian D.; Morgan, Leanne K.

    2018-06-01

    Freshwater contained within the submarine extensions of coastal aquifers is increasingly proposed as a freshwater source for coastal communities. However, the extent to which offshore freshwater supports onshore pumping is currently unknown on a global scale. This study provides the first attempt to examine the likely prevalence of situations where offshore freshwater influences onshore salinities, considering various sites from around the world. The groundwater conditions in twenty-seven confined and semi-confined coastal aquifers with plausible connections to inferred or observed offshore freshwater are explored. The investigation uses available onshore salinities and groundwater levels, and offshore salinity knowledge, in combination with analytical modelling, to develop simplified conceptual models of the study sites. Seven different conceptual models are proposed based on the freshwater-saltwater extent and insights gained from analytical modelling. We consider both present-day and pre-development conditions in assessing potential modern contributions to offshore fresh groundwater. Conceptual models also include interpretations of whether offshore freshwater is a significant factor influencing onshore salinities and well pumping sustainability. The results indicate that onshore water levels have declined between pre-development and present-day conditions in fourteen of the fifteen regions for which pre-development data are available. Estimates of the associated steady-state freshwater extents show the potential for considerable offshore fresh groundwater losses accompanying these declines. Both present-day and pre-development heads are insufficient to account for the observed offshore freshwater in all cases where adequate data exist. This suggests that paleo-freshwater and/or aquifer heterogeneities contribute significantly to offshore freshwater extent. Present-day heads indicate that active seawater intrusion (SWI) will eventually impact onshore pumping

  15. Paleocene stratigraphic plays in Uruguay offshore

    International Nuclear Information System (INIS)

    Morales, E; Soto, M; Ferro, S; Tomasini, J; De Santa Ana, H; Conti, B.; Veroslavsky, G.

    2012-01-01

    The Uruguayan continental margin offshore evolution is represented by three large mega sequences: pre rift, rift and post rift, which are correlated with other South Atlantic basins. The tectonic and stratigraphic knowledge about the Uruguayan offshore evolution enable a hydrocarbon potential approximation . The mapping of the seismic depositional sequences are covered by deep basins. The methodology used identify the migration of Uruguayan side depo centers such as the stratigraphic plays group in particular a prospective Paleocene sequence

  16. ISM Approach to Model Offshore Outsourcing Risks

    OpenAIRE

    Kumar, Sunand; Sharma, Rajiv Kumar; Chauhan, Prashant

    2014-01-01

    [EN] In an effort to achieve a competitive advantage via cost reductions and improved market responsiveness, organizations are increasingly employing offshore outsourcing as a major component of their supply chain strategies. But as evident from literature number of risks such as Political risk, Risk due to cultural differences, Compliance and regulatory risk, Opportunistic risk and Organization structural risk, which adversely affect the performance of offshore outsourcing in a supply chain ...

  17. 2014 Offshore Wind Market and Economic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, Bruce [Navigant Consulting, Inc., Burlington, MA (United States)

    2014-08-25

    The objective of this report is to provide a comprehensive annual assessment of the U.S. offshore wind market.This 3rd annual report focuses on new developments that have occurred in 2014. The report provides stakeholders with a reliable and consistent data source addressing entry barriers and U.S. competitiveness in the offshore wind market. Available for download are both the full report and the report's underlying data.

  18. Offshore wind turbines reliability, availability and maintenance

    CERN Document Server

    Tavner, Peter

    2012-01-01

    The first book to specifically focus on offshore wind turbine technology and which addresses practically wind turbine reliability and availability. The book draws on the author's experience of power generation reliability and availability and the condition monitoring of that plant to describe the problems facing the developers of offshore wind farms and the solutions available to them to raise availability, reduce cost of energy and improve through life cost.

  19. Offshore wind industry capabilities in the UK

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    This report summarises the results of a questionnaire survey distributed to companies and organisations interested in opportunities in offshore wind energy industries that may results in the improved competitiveness of the industry. The potential areas of advantage for the UK offshore industry are examined including resource and design conditions, turbine design and manufacture, electrical systems, operation and maintenance, project management and finance. Networking and communications are considered.

  20. Effects of offshore wind farms on birds

    DEFF Research Database (Denmark)

    Petersen, Ib Krag; Fox, Anthony David; Desholm, Mark

    På konferencen "Offshore Wind Energy Development Site Assessment and Characterization: Evaluation of the Current Status and European Experience" blev der gjort rede for danske erfaringer med effekten af havvindmølleparker på havfugle.......På konferencen "Offshore Wind Energy Development Site Assessment and Characterization: Evaluation of the Current Status and European Experience" blev der gjort rede for danske erfaringer med effekten af havvindmølleparker på havfugle....