WorldWideScience

Sample records for plate boundary forces

  1. Analytical solution of conjugate turbulent forced convection boundary layer flow over plates

    Directory of Open Access Journals (Sweden)

    Joneydi Shariatzadeh Omid

    2016-01-01

    Full Text Available A conjugate (coupled forced convection heat transfer from a heated conducting plate under turbulent boundary layer flow is considered. A heated plate of finite thickness is cooled under turbulent forced convection boundary layer flow. Because the conduction and convection boundary layer flow is coupled (conjugated in the problem, a semi-analytical solution based on Differential Transform Method (DTM is presented for solving the non-linear integro-differential equation occurring in the problem. The main conclusion is that in the conjugate heat transfer case the temperature distribution of the plate is flatter than the one in the non-conjugate case. This feature is more pronounced under turbulent flow when compared with the laminar flow.

  2. Obliquity along plate boundaries

    Science.gov (United States)

    Philippon, Mélody; Corti, Giacomo

    2016-12-01

    Most of the plate boundaries are activated obliquely with respect to the direction of far field stresses, as roughly only 8% of the plate boundaries total length shows a very low obliquity (ranging from 0 to 10°, sub-orthogonal to the plate displacement). The obliquity along plate boundaries is controlled by (i) lateral rheological variations within the lithosphere and (ii) consistency with the global plate circuit. Indeed, plate tectonics and magmatism drive rheological changes within the lithosphere and consequently influence strain localization. Geodynamical evolution controls large-scale mantle convection and plate formation, consumption, and re-organization, thus triggering plate kinematics variations, and the adjustment and re-orientation of far field stresses. These geological processes may thus result in plate boundaries that are not perpendicular but oblique to the direction of far field stresses. This paper reviews the global patterns of obliquity along plate boundaries. Using GPlate, we provide a statistical analysis of present-day obliquity along plate boundaries. Within this framework, by comparing natural examples and geological models, we discuss deformation patterns and kinematics recorded along oblique plate boundaries.

  3. Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate

    DEFF Research Database (Denmark)

    Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo

    2010-01-01

    In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained...

  4. Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate

    DEFF Research Database (Denmark)

    Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo;

    2010-01-01

    In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained...

  5. MHD forced convective laminar boundary layer flow from a convectively heated moving vertical plate with radiation and transpiration effect.

    Science.gov (United States)

    Uddin, Md Jashim; Khan, Waqar A; Ismail, A I Md

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to x(m) whilst the magnetic field and mass transfer velocity are taken to be proportional to x((m-1)/2) where x is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory.

  6. Plate boundary forces in the vicinity of Trinidad-the-transition from transpression to transtension in the Southern Caribbean plate boundary zones

    Energy Technology Data Exchange (ETDEWEB)

    Algar, S.T.; Pindell, J.L. (Dartmouth College, Hanover, NH (United States))

    1993-02-01

    Deformation in the southern Caribbean plate boundary zones as recorded in the Northern Range of Trinidad initiated in the Oligocene with northward vergent gravity sliding of Northern Range sediments due to uplift and oversteepening of the previously passive margin by the eastward migration of the Caribbean flexural forebulge. Progressive east-southeast transvergence of the Caribbean Plate with respect to South America overthrust incorporated the Northern Range sediments into the Caribbean accretionary prism, thrusting them south-southeast to produce a Middle Miocene transpressive foreland fold and thrust belt in southern Trinidad. Late Miocene deformation within Trinidad was increasingly dominated by right-lateral strike-slop (RLSS) faulting, at the expense of transpressive compressional features. Right-stepping of RLSS motion initiated the Gulf of Paria and Caroni pull-apart basins, Since Early Pliocene these basins and other areas to the north of Trinidad have undergone north-south extension in addition to east-west trending RLSS. Such extension caused the northward withdrawal of Caribbean terranes from atop of the Northern Range, Resulting in rapid isostatically induced uplift (approximately 0.5 mmyr[sup -1]). This change in deformation style may relate to a hitherto unrecognized shift in the relative motion of the eastern Caribbean Plate with respect to South America: from east-southeast-directed transpression to east-northeast-directed transtension.

  7. 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.

  8. Film Condensation with and Without Body Force in Boundary-Layer Flow of Vapor Over a Flat Plate

    Science.gov (United States)

    Chung, Paul M.

    1961-01-01

    Laminar film condensation under the simultaneous influence of gas-liquid interface shear and body force (g force) is analyzed over a flat plate. Important parameters governing condensation and heat transfer of pure vapor are determined. Mixtures of condensable vapor and noncondensable gas are also analyzed. The conditions under which the body force has a significant influence on condensation are determined.

  9. The seismotectonics of plate boundaries

    Science.gov (United States)

    Berger, J.; Brune, J. N.; Goodkind, J.; Wyatt, F.; Agnew, D. C.; Beaumont, C.

    1981-01-01

    Research on the seismotectonics of plate boundaries is summarized. Instrumental development and an observational program designed to study various aspects of the seismotectonics of southern California and the northern Gulf of California are described. A unique superconducting gravimeter was further developed and supported under this program for deployment and operation at several sites. Work on Earth tides is also discussed.

  10. On a character of the forced vibrations of two-layer plate in the second boundary value problem

    Directory of Open Access Journals (Sweden)

    Poghosyan H. M.

    2007-06-01

    Full Text Available The three-dimensional dynamic problem of the elasticity theory on forced vibration of orthotropic plate at coulomb friction between layers is solved by the asymptotic method. The bottom obverse surface is subject to external dynamic influences, and top - is rigidly fixed. The common asymptotic solution of the problem is found. The closed solution for particular type of problems is found. The resonance arising conditions are established. It is known, that constant tangential displacements acting to the second layer do not influence in stress-strain state of the first layer. It is shown, that the same phenomenon with the big accuracy remains in force at linearly varying on coordinates influences.

  11. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    Faical Ramdani; Omar Kettani; Benaissa Tadili

    2015-06-01

    Seismic triggering at plate boundaries has a very complex nature that includes seismic events at varying distances. The spatial orientation of triggering cannot be reduced to sequences from the main shocks. Seismic waves propagate at all times in all directions, particularly in highly active zones. No direct evidence can be obtained regarding which earthquakes trigger the shocks. The first approach is to determine the potential linked zones where triggering may occur. The second step is to determine the causality between the events and their triggered shocks. The spatial orientation of the links between events is established from pre-ordered networks and the adapted dependence of the spatio-temporal occurrence of earthquakes. Based on a coefficient of synchronous seismic activity to grid couples, we derive a network link by each threshold. The links of high thresholds are tested using the coherence of time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension.

  12. Diffuse oceanic plate boundaries: Strain rates, vertically averaged rheology, and comparisons with narrow plate boundaries and stable plate interiors

    Science.gov (United States)

    Gordon, Richard G.

    Diffuse plate boundaries occur in both oceanic and continental lithosphere and cover ≈ 15% of Earth's solid surface. The fastest plate speeds accommodated across diffuse oceanic plate boundaries are ≈ 15 mm/yr. The smallest strain rates averaged across narrow plate boundaries are at least 102 times larger than the largest strain rates across diffuse oceanic plate boundaries and at least 102 times larger than those across stable plate interiors. The effective viscosity (ηeff) of the lithosphere is estimated from the ratio of vertically averaged shear stresses to strain rates for three tectonic settings: (i) oceanic transform fault zones, for which ηeff = 3 ×1016 to 5×1019 Pa s, comparable to estimates for the asthenosphere, (ii) diffuse oceanic plate boundaries, for which ηeff = 1×1023 to 6×l023 Pa s, ≈ 10 times larger than for diffuse continental plate boundaries, and (iii) stable plate interiors, for which ηeff = 1x1024 to 2×1027 Pa s. The rheology of oceanic lithosphere over times longer than earthquake cycles is modeled as a plastic layer overlying a layer that deforms by creeping flow [Martinod and Davy, 1992]. Oceanic lithosphere deforms when the yield strength of the upper lithosphere is exceeded. The vertically averaged rheology of deforming oceanic lithosphere can be approximated by a power-law fluid for which ɛ. ∝ (τs)n where ɛ. is the rate of shear strain and τs is the shear stress. If the ratio of the yield strength of the upper lithosphere to the force required to deform the lower lithosphere at a strain rate of 10-16 s-1 is varied from 10-2 to 102 , the calculated value of n varies from ≈3 to ≈300. The map-view aspect ratio of a deforming zone in a thin sheet of power-law fluid is proportional to n-½ [England et al., 1985]. A profile of displacement versus distance inferred from a seismic profile across the Central Indian Basin (India-Capricorn diffuse oceanic plate boundary), where the lithosphere is about 60-Myr old

  13. FRACTURE CALCULATION OF BENDING PLATES BY BOUNDARY COLLOCATION METHOD

    Institute of Scientific and Technical Information of China (English)

    王元汉; 伍佑伦; 余飞

    2003-01-01

    Fracture of Kirchhoff plates is analyzed by the theory of complex variables and boundary collocation method. The deflections, moments and shearing forces of the plates are assumed to be the functions of complex variables. The functions can satisfy a series of basic equations and governing conditions, such as the equilibrium equations in the domain, the boundary conditions on the crack surfaces and stress singularity at the crack tips. Thus, it ts only necessary to consider the boundary conditions on the external boundaries of the plate, which can be approximately satisfied by the collocation method and least square technique. Different boundary conditions and loading cases of the cracked plates are analyzed and calculated. Compared to other methods, the numerical examples show that the present method has many advantages such as good accuracy and less computer time This is an effective semi-analytical and semi-numerical method.

  14. Mixed boundary conditions for piezoelectric plates

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    For plate bending and stretching problems in piezoelectric materials,the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate mixed boundary conditions accurate to all order.A decay analysis technique is used to establish necessary conditions that the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the plate.For the case of axisymmetric bending and stretching of a circular plate,these decaying state conditions are obtained explicitly for the first time when the mixed conditions are imposed on the plate edge.They are then used for the correct formulation of boundary conditions for the interior solution.

  15. Casimir force between metal plate and dielectric plate

    Institute of Scientific and Technical Information of China (English)

    刘中柱; 邵成刚; 罗俊

    1999-01-01

    The Casimir effect between metal plate and dielectric plate is discussed with 1+1-dimensional potential model without using cut-off method. Calculation shows that the Casimir force between metal plate and dielectric plate is determined not only by the potential V0, the dielectric thickness and the distance α between the metal plate and dielectric plate, but also by the dimension of the vessel. When α is far less than the dimension of the vessel, the Casimir force Fc∝α(-1); conversely Fc∝α-2. This result is significant for Casimir force experiment.

  16. Turbulent boundary layer over flexible plates

    Science.gov (United States)

    Rostami, Parand; Ioppolo, Tindaro

    2016-11-01

    This research describes the structure of a turbulent boundary layer flow with a zero pressure gradient over elastic plates. The elastic plates made of a thin aluminum sheets with thickness between 50 and 500 microns were placed on the floor of a subsonic wind tunnel and exposed to a turbulent boundary layer flow with a free stream velocity between 20m/s and 100m/s. The ceiling of the test section of the wind tunnel is adjustable so that a nearly zero pressure gradient is obtained in the test section. Hot-wire anemometry was used to measure the velocity components. Mean, fluctuating velocities and Reynolds stresses will be presented and compared with the values of a rigid plate.

  17. Hydrodynamic Boundary Conditions and Dynamic Forces between Bubbles and Surfaces

    Science.gov (United States)

    Manor, Ofer; Vakarelski, Ivan U.; Tang, Xiaosong; O'Shea, Sean J.; Stevens, Geoffrey W.; Grieser, Franz; Dagastine, Raymond R.; Chan, Derek Y. C.

    2008-07-01

    Dynamic forces between a 50μm radius bubble driven towards and from a mica plate using an atomic force microscope in electrolyte and in surfactant exhibit different hydrodynamic boundary conditions at the bubble surface. In added surfactant, the forces are consistent with the no-slip boundary condition at the mica and bubble surfaces. With no surfactant, a new boundary condition that accounts for the transport of trace surface impurities explains variations of dynamic forces at different speeds and provides a direct connection between dynamic forces and surface transport effects at the air-water interface.

  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. Tethyan collision forces and the stress field of the Eurasian plate

    NARCIS (Netherlands)

    Warners-Ruckstuhl, K.N.; Govers, R.; Wortel, R.

    2013-01-01

    Resistive forces along convergent plate boundaries have a major impact on surface deformation, most visibly at collisional plate boundaries. Although quantification of these forces is key to understanding the evolution and present state of mountain belts, they remain highly uncertain due to the comp

  20. Vibration suppression for laminated composite plates with arbitrary boundary conditions

    Science.gov (United States)

    Li, J.; Narita, Y.

    2013-11-01

    An analysis of vibration suppression for laminated composite plates subject to active constrained layer damping under various boundary conditions is presented. Piezoelectric-fiber-reinforced composites (PFRCs) are used as active actuators, and the effect of PFRC patches on vibration control is reported here. An analytical approach is expanded to analyze the vibration of laminated composites with arbitrary boundary conditions. By using Hamilton's principle and the Rayleigh-Ritz method, the equation of motion for the resulting electromechanical coupling system is derived. A velocity feedback control rule is employed to obtain an effective active damping in the vibration control. The orientation effect of piezoelectric fibers in the PFRC patches on the suppression of forced vibrations is also investigated.

  1. Global Plate Driving Forces at 50Ma

    Science.gov (United States)

    Butterworth, N. P.; Quevedo, L. E.; Müller, R. D.

    2011-12-01

    We apply a novel workflow utilising the BEM-Earth geodynamic software to analyse the global coupled plate-mantle dynamics at 50 Ma. A subduction history model based on kinematic data going as far back as 80 Ma was developed using the GPlates software. Advection of the plates into the mantle takes into account the absolute plate motions and lithospheric thickness derived from its age to produce an estimated density heterogeneity initial model condition in the upper mantle. The resulting global model consists of regions of a mantle viscosity and density structure that is post-processed to ensure smooth non-overlapping 3D surfaces. BEM-Earth is then free to evolve the model toward the 50 Ma solution. The evolution of the model is driven by self-consistent buoyancy driven mantle dynamics. We use the model velocity output to quantify changes in forces driving the plates before and after 50 Ma. We analyse the rapid change in plate motion of India, Africa and plates in the Pacific Ocean basin by considering slab-pull, ridge-push and mantle drag/suction forces that naturally result from such top-down driven mantle flow. We compare the results with plate kinematic reconstructions and other geological observations.

  2. Study on Scattering Wave Force of Horizontal and Vertical Plate Type Breakwaters

    Institute of Scientific and Technical Information of China (English)

    WANG Ke; ZHANG Xi; GAO Xin

    2011-01-01

    The interaction between wave and horizontal and vertical plates is investigated by the boundary element method,and the relations of wave exciting force with plate thickness,submergence and length are obtained.It is found that:1)The efficient wave exciting force exists while plate submergence is less than 0.5 m,and the plate is very thin with order O(0.005 m).2) The maximum heave wave exciting force exists,and it is the main factor for surface and submerged horizontal plate while the roll force can be ignored.3) The maximum sway wave exciting force exists,it is the main factor for surface or submerged vertical plate,and the roll force is about 20 times of horizontal plate.

  3. Casimir Force Correction Between Parallel Polysilicon Plates

    Institute of Scientific and Technical Information of China (English)

    丁建宁; 孟永钢; 温诗铸

    2002-01-01

    Both the size of the components and the separation between them in some microelectromechanical systems (MEMS) are already in the sub-micrometer regime, where quantum mechanical effects such as the Casimir effect will need to be considered. This paper theoretically analyzes the roughness, electrical conductivity, and temperature corrections due to the Casimir force between two parallel polysilicon plates. The theoretical results show that the combined effects of roughness, conductivity and temperature cause a maximum relative error of the Casimir force per unit area of 26.2% between parallel polysilicon plates separated by 1 μm. Therefore, the surface roughness and finite conductivity corrections should be taken into account when calculating precise Casimir forces with separations on the order of 1 μm.

  4. Estimating area of inclusions in anisotropic plates from boundary data

    CERN Document Server

    Morassi, Antonino; Vessella, Sergio

    2011-01-01

    We consider the inverse problem of determining the possible presence of an inclusion in a thin plate by boundary measurements. The plate is made by non-homogeneous linearly elastic material belonging to a general class of anisotropy. The inclusion is made by different elastic material. Under some a priori assumptions on the unknown inclusion, we prove constructive upper and lower estimates of the area of the unknown defect in terms of an easily expressed quantity related to work, which is given in terms of measurements of a couple field applied at the boundary and of the induced transversal displacement and its normal derivative taken at the boundary of the plate.

  5. 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.

  6. Extending Alaska's plate boundary: tectonic tremor generated by Yakutat subduction

    Science.gov (United States)

    Wech, Aaron G.

    2016-01-01

    The tectonics of the eastern end of the Alaska-Aleutian subduction zone are complicated by the inclusion of the Yakutat microplate, which is colliding into and subducting beneath continental North America at near-Pacific-plate rates. The interaction among these plates at depth is not well understood, and further east, even less is known about the plate boundary or the source of Wrangell volcanism. The drop-off in Wadati-Benioff zone (WBZ) seismicity could signal the end of the plate boundary, the start of aseismic subduction, or a tear in the downgoing plate. Further compounding the issue is the possible presence of the Wrangell slab, which is faintly outlined by an anemic, eastward-dipping WBZ beneath the Wrangell volcanoes. In this study, I performed a search for tectonic tremor to map slow, plate-boundary slip in south-central Alaska. I identified ∼11,000 tremor epicenters, which continue 85 km east of the inferred Pacific plate edge marked by WBZ seismicity. The tremor zone coincides with the edges of the downgoing Yakutat terrane, and tremors transition from periodic to continuous behavior as they near the aseismic Wrangell slab. I interpret tremor to mark slow, semicontinuous slip occurring at the interface between the Yakutat and North America plates. The slow slip region lengthens the megathrust interface beyond the WBZ and may provide evidence for a connection between the Yakutat slab and the aseismic Wrangell slab.

  7. Novel boundary element method for resolving plate bending problems

    Institute of Scientific and Technical Information of China (English)

    陈颂英; 王乐勤; 焦磊

    2003-01-01

    This paper discusses the application of the boundary contour method for resolving plate bending problems. The exploitation of the integrand divergence free property of the plate bending boundary integral equation based on the Kirchhoff hypothesis and a very useful application of Stokes' Theorem are presented to convert surface integrals on boundary elements to the computation of bending potential functions on the discretized boundary points, even for curved surface elements of arbitrary shape. Singularity and treatment of the discontinued corner point are not needed at all. The evaluation of the physics variant at internal points is also shown in this article. Numerical results are presented for some plate bending problems and compared against analytical and previous solutions.

  8. 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.

  9. Kinematics to dynamics in the New Zealand plate-boundary zone

    Science.gov (United States)

    Lamb, S. H.

    2013-12-01

    New Zealand straddles the boundary between the Australian and Pacific plate, with a transition from subduction of Pacific oceanic lithosphere beneath North Island, to oblique continental collision in South Island. Cenozoic relative plate motion has resulted in a complex pattern of faulting and block rotation in a zone up to 250 km wide, with displacements on individual faults up to 100s of kilometres. Active deformation must be driven by a combination of plate-boundary forces and internal buoyancy forces. I use a compilation of seismic reflection/refraction studies and high quality receiver function analyses, together with simple Airy isostasy, to determine regional crustal and mantle structure. Integration of the vertical normal stress to the base of the deforming layer yields the buoyancy stress. Horizontal gradients of this can be compared with horizontal gradients of strain rate, using the method of England & Molnar (1997), in the context of a simple thin sheet model of deformation. Thus, if deformation is that of a Newtonian fluid, then appropriate combinations of the horizontal gradients of vorticity and dilatation are related to gradients of buoyancy stress by the fluid viscosity. However, the short term geodetic deformation is strongly biased by elastic strain accumulation related to locking on the plate interface, and cannot be used to determine the plate-boundary velocity field averaged over many seismic cycles (see Lamb & Smith 2013). Therefore, I derive here a velocity field for the plate-boundary zone, which is representative of deformation over tens of thousands of years. This is based on an inversion of fault slip, strain rate azimuth and paleomagnetic data, in the context of the short term relative plate motions, solved in a network of triangles spanning the plate-boundary, using the method of Lamb (2000). A comparison of gradients of buoyancy stress with the appropriate combinations of gradients of vorticity and dilatation shows that deformation in

  10. Application of Laser Ranging and VLBI Data to a Study of Plate Tectonic Driving Forces

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The conditions under which changes in plate driving or resistive forces associated with plate boundary earthquakes are measurable with laser ranging or very long base interferometry were investigated. Aspects of plate forces that can be characterized by such measurements were identified. Analytic solutions for two dimensional stress diffusion in a viscoelastic plate following earthquake faulting on a finite fault, finite element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting, and quantitative constraints from modeling of global intraplate stress on the magnitude of deviatoric stress in the lithosphere are among the topics discussed.

  11. Inversion for the driving forces of plate tectonics

    Science.gov (United States)

    Richardson, R. M.

    1983-01-01

    Inverse modeling techniques have been applied to the problem of determining the roles of various forces that may drive and resist plate tectonic motions. Separate linear inverse problems have been solved to find the best fitting pole of rotation for finite element grid point velocities and to find the best combination of force models to fit the observed relative plate velocities for the earth's twelve major plates using the generalized inverse operator. Variance-covariance data on plate motion have also been included. Results emphasize the relative importance of ridge push forces in the driving mechanism. Convergent margin forces are smaller by at least a factor of two, and perhaps by as much as a factor of twenty. Slab pull, apparently, is poorly transmitted to the surface plate as a driving force. Drag forces at the base of the plate are smaller than ridge push forces, although the sign of the force remains in question.

  12. Inversion for the driving forces of plate tectonics

    Science.gov (United States)

    Richardson, R. M.

    1983-01-01

    Inverse modeling techniques have been applied to the problem of determining the roles of various forces that may drive and resist plate tectonic motions. Separate linear inverse problems have been solved to find the best fitting pole of rotation for finite element grid point velocities and to find the best combination of force models to fit the observed relative plate velocities for the earth's twelve major plates using the generalized inverse operator. Variance-covariance data on plate motion have also been included. Results emphasize the relative importance of ridge push forces in the driving mechanism. Convergent margin forces are smaller by at least a factor of two, and perhaps by as much as a factor of twenty. Slab pull, apparently, is poorly transmitted to the surface plate as a driving force. Drag forces at the base of the plate are smaller than ridge push forces, although the sign of the force remains in question.

  13. A diffuse plate boundary model for Indian Ocean tectonics

    Science.gov (United States)

    Wiens, D. A.; Demets, C.; Gordon, R. G.; Stein, S.; Argus, D.

    1985-01-01

    It is suggested that motion along the virtually aseismic Owen fracture zone is negligible, so that Arabia and India are contained within a single Indo-Arabian plate divided from the Australian plate by a diffuse boundary. The boundary is a zone of concentrated seismicity and deformation commonly characterized as 'intraplate'. The rotation vector of Australia relative to Indo-Arabia is consistent with the seismologically observed 2 cm/yr of left-lateral strike-slip along the Ninetyeast Ridge, north-south compression in the Central Indian Ocean, and the north-south extension near Chagos.

  14. Geodynamic Evolution of the Nubia-Arabia-Somalia Plate Boundary System

    Science.gov (United States)

    Reilinger, R. E.; McClusky, S.; Vernant, P.; Ogubazghi, G.; Fisseha, S.; Arrajehi, A.; Bendick, R. O.; Sholan, J.

    2009-12-01

    We present a geodynamic scenario for the evolution of the Nubia (Nu)-Arabia (Ar)-Somalia (So) plate boundary system that is based on new geodetic constraints on the kinematics of active deformation, and published estimates of the timing of regional tectonic processes. This scenario supports two, long debated, principal hypotheses for plate dynamics, 1) plate motions are driven primarily by sinking of oceanic lithosphere at subduction zones, and 2) the lithosphere is strong in relation to plate boundaries and drag forces on the base of the lithosphere (and likely, resisting forces associate with continental collision). 1) During the Late Oligocene (~30 Ma), domal uplift of the Afar region due to the Afar hot spot caused regional extension and the initial development of the Afar Triple Junction (TJ) along pre-existing zones of weakness; 2) The So-Nu plate boundary, East African Rift (EAR), developed at a slow rate due to the absence of boundary-normal extensional stresses (i.e., no subduction “pulling” the So Plate), slow motion that continues to the present; 3) Larger extensional stresses across the Nu-Ar and Ar-So boundaries (Red Sea and Gulf of Aden) due to active subduction of the Neotethys ocean lithosphere beneath Eu caused more rapid extension of these early rifts, with full scale continental rifting beginning ~ 25-30 Ma; 4) Between 16 - 11 Ma full ocean rifting in the Gulf of Aden caused a decrease in the forces transmitted to the So and Nu plates, causing slowing of the Nu and So plates with respect to Eu and Ar, and (possibly) an additional component of N-S oriented extension across the Red Sea; 5) Around this time (~10 Ma), activity shifted from the Gulf of Suez to the DSF system in the N Red Sea, and the Danakil Block in the southern Red Sea began rotating with respect to Nu and Ar, both changes related to the change in Nu-Ar relative motion; and 6) The balance of forces on the plate system have remained roughly unchanged since ~10 Ma, as have

  15. BOLIVAR & GEODINOS: Investigations of the Southern Caribbean Plate Boundary

    Science.gov (United States)

    Levander, A.; Schmitz, M.; Working Groups, B.

    2006-12-01

    The southern Caribbean-South American plate boundary has many similarities to California's San Andreas system: 1) The CAR-SA system consists of a series of strands of active right lateral strike-slip faults extending >1000 km from the Antilles subduction zone. This system has several names and includes the El Pilar, Coche, San Sebastian, Moron, and Oca faults. 2) The CAR-SA relative velocity has been about 20 mm/yr of mostly right lateral motion since about 55 Ma, giving a total displacement on the CAR-SA plate boundary similar to that of the San Andreas system. 3) The plate boundary has about 10% convergence in western SA, with less as one moves eastward due to relative convergence between North and South America. 4) The CAR-SA system has fold and thrust belts best developed continentward of the strike-slip faults, similar to the San Andreas. 5) There is a big bend in the CAR plate boundary at approximately the same distance from the Antilles trench as the big bend in Southern California is from the Cascadia subduction zone. The tectonic origins of the CAR-SA plate boundary and the San Andreas are very different, however, despite the similarities between the systems. Rather than impingement of a ridge on a trench, the CAR-SA system is thought to have resulted from a continuous oblique collision of the southern end of a Cretaceous island arc system with the northern edge of South America. During this process the CAR island arc and the modern CAR plate overrode a proto-Caribbean plate and destroyed a Mesozoic passive margin on the northern edge of SA. BOLIVAR and GEODINOS are multi-disciplinary investigations of the lithosphere and deeper structures associated with the diffuse CAR-SA plate boundary zone. We review a number of observations regarding the plate boundary obtained or confirmed from these studies: 1) The Caribbean Large Igneous Province, being overridden by the Maracaibo block in western Venezuela, can be identified beneath Aruba and coastal Venezuela

  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. Application of laser ranging and VLBI data to a study of plate tectonic driving forces. [finite element method

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The measurability of changes in plate driving or resistive forces associated with plate boundary earthquakes by laser rangefinding or VLBI is considered with emphasis on those aspects of plate forces that can be characterized by such measurements. Topics covered include: (1) analytic solutions for two dimensional stress diffusion in a plate following earthquake faulting on a finite fault; (2) two dimensional finite-element solutions for the global state of stress at the Earth's surface for possible plate driving forces; and (3) finite-element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting.

  18. Control of boundary layer transition location and plate vibration in the presence of an external acoustic field

    Science.gov (United States)

    Maestrello, L.; Grosveld, F. W.

    1991-01-01

    The experiment is aimed at controlling the boundary layer transition location and the plate vibration when excited by a flow and an upstream sound source. Sound has been found to affect the flow at the leading edge and the response of a flexible plate in a boundary layer. Because the sound induces early transition, the panel vibration is acoustically coupled to the turbulent boundary layer by the upstream radiation. Localized surface heating at the leading edge delays the transition location downstream of the flexible plate. The response of the plate excited by a turbulent boundary layer (without sound) shows that the plate is forced to vibrate at different frequencies and with different amplitudes as the flow velocity changes indicating that the plate is driven by the convective waves of the boundary layer. The acoustic disturbances induced by the upstream sound dominate the response of the plate when the boundary layer is either turbulent or laminar. Active vibration control was used to reduce the sound induced displacement amplitude of the plate.

  19. Free, transverse vibrations of thin plates with discontinuous boundary conditions

    Science.gov (United States)

    Febbo, M.; Vera, S. A.; Laura, P. A. A.

    2005-03-01

    Vibrations of circular and rectangular plates clamped on part of the boundary and simply supported along the remainder are analyzed by means of a method of perturbation of boundary conditions. This approach appears to be simple and straightforward, giving excellent results for the first mode and its versatility permits to extend it to higher modes of vibration without difficulty. Furthermore, it is shown that the fundamental frequency coefficient can also be determined using a modified Galerkin approach and very simple polynomial coordinate functions which yield good engineering accuracy.

  20. 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

  1. Tectonics of the Nazca-Antarctic plate boundary

    Science.gov (United States)

    Anderson-Fontana, Sandra; Larson, Roger L.; Engeln, Joseph F.; Lundgren, Paul; Stein, Seth

    1987-01-01

    A new bathymetric chart of part of the Chile transform system is constructed, based mainly on an R/V Endeavor survey from 100 deg W to its intersection with the East Ridge of the Juan Fernandez microplate. A generally continuous lineated trend can be followed through the entire region, with the transform valley being relatively narrow and well-defined from 109 deg W to approximately 104 deg 30 min W. The fracture zone then widens to the east, with at least two probable en echelon offsets to the south at 104 deg and 102 deg W. Six new strike-slip mechanisms along the Chile Transform and one normal fault mechanism near the northern end of the Chile Rise, inverted together with other plate-motion data from the eastern portion of the boundary, produce a new best-fit Euler pole for the Nazca-Antarctic plate pair, providing tighter constraints on the relative plate motions.

  2. Tectonics of the Nazca-Antarctic plate boundary

    Science.gov (United States)

    Anderson-Fontana, Sandra; Larson, Roger L.; Engeln, Joseph F.; Lundgren, Paul; Stein, Seth

    1987-01-01

    A new bathymetric chart of part of the Chile transform system is constructed, based mainly on an R/V Endeavor survey from 100 deg W to its intersection with the East Ridge of the Juan Fernandez microplate. A generally continuous lineated trend can be followed through the entire region, with the transform valley being relatively narrow and well-defined from 109 deg W to approximately 104 deg 30 min W. The fracture zone then widens to the east, with at least two probable en echelon offsets to the south at 104 deg and 102 deg W. Six new strike-slip mechanisms along the Chile Transform and one normal fault mechanism near the northern end of the Chile Rise, inverted together with other plate-motion data from the eastern portion of the boundary, produce a new best-fit Euler pole for the Nazca-Antarctic plate pair, providing tighter constraints on the relative plate motions.

  3. Spatially developing turbulent boundary layer on a flat plate

    CERN Document Server

    Lee, J H; Hutchins, N; Monty, J P

    2012-01-01

    This fluid dynamics video submitted to the Gallery of Fluid motion shows a turbulent boundary layer developing under a 5 metre-long flat plate towed through water. A stationary imaging system provides a unique view of the developing boundary layer as it would form over the hull of a ship or fuselage of an aircraft. The towed plate permits visualisation of the zero-pressure-gradient turbulent boundary layer as it develops from the trip to a high Reynolds number state ($Re_\\tau \\approx 3000$). An evolving large-scale coherent structure will appear almost stationary in this frame of reference. The visualisations provide an unique view of the evolution of fundamental processes in the boundary layer (such as interfacial bulging, entrainment, vortical motions, etc.). In the more traditional laboratory frame of reference, in which fluid passes over a stationary body, it is difficult to observe the full evolution and lifetime of turbulent coherent structures. An equivalent experiment in a wind/water-tunnel would requ...

  4. Non-equilibrium Casimir force between vibrating plates.

    Directory of Open Access Journals (Sweden)

    Andreas Hanke

    Full Text Available We study the fluctuation-induced, time-dependent force between two plates confining a correlated fluid which is driven out of equilibrium mechanically by harmonic vibrations of one of the plates. For a purely relaxational dynamics of the fluid we calculate the fluctuation-induced force generated by the vibrating plate on the plate at rest. The time-dependence of this force is characterized by a positive lag time with respect to the driving. We obtain two distinctive contributions to the force, one generated by diffusion of stress in the fluid and another related to resonant dissipation in the cavity. The relation to the dynamic Casimir effect of the electromagnetic field and possible experiments to measure the time-dependent Casimir force are discussed.

  5. Stress State Of Plate With Incisions Under The Action Of Oscillating Concentrated Forces

    Directory of Open Access Journals (Sweden)

    Shvabyuk Vasyl’

    2015-09-01

    Full Text Available This paper proposes the novel technique for analysis of dynamic stress state of multi-connected infinite plates under the action of oscillating forces. Calculation of 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 algorithmis based on the method of mechanical quadratures and collocation technique. The algorithm is effective in the analysis of the stress state caused by steady-state vibrations of plates.

  6. Plates of the dinosaur stegosaurus: forced convection heat loss fins?

    Science.gov (United States)

    Farlow, J O; Thompson, C V; Rosner, D E

    1976-06-11

    It is suggested that the plates along the arched back and tail of Stegosaurus served an important thermoregulatory function as forced convection "fins." Wind tunnel experiments on finned models, internal heat conduction calculations, and direct observations of the morphology and internal structure of stegosaur plates support this hypothesis, demonstrating the comparative effectiveness of the plates as heat dissipaters, controllable through input blood flow rate, temperature, and body orientation (with respect to wind).

  7. How transpressive is the northern Caribbean plate boundary?

    Science.gov (United States)

    Corbeau, J.; Rolandone, F.; Leroy, S.; Meyer, B.; Mercier de Lépinay, B.; Ellouz-Zimmermann, N.; Momplaisir, R.

    2016-04-01

    Transpressive deformation at the northern Caribbean plate boundary is accommodated mostly by two major strike-slip faults, but the amount and location of accommodation of the compressional component of deformation are still debated. We collected marine geophysical data including multibeam bathymetry and multichannel seismic reflection profiles along this plate boundary around Hispaniola, in the Jamaica Passage, and in the Gulf of Gonâve. The data set allows us to image the offshore active strike-slip faults as well as the compressional structures. We confirm that the Enriquillo-Plantain-Garden Fault Zone (EPGFZ) in the Jamaica Passage has a primary strike-slip motion, as indicated by active left-lateral strike-slip-related structures, i.e., restraining bend, asymmetrical basin, en echelon pressures ridges, and horsetail splay. Based on topographic cross sections across the EPGFZ, we image a very limited compressional component, if any, for at least the western part of the Jamaica Passage. Toward the east of the Jamaica Passage, the fault trace becomes more complex, and we identify adjacent compressional structures. In the Gulf of Gonâve, distributed folding and thrust faulting of the most recent sediments indicate active pervasive compressional tectonics. Estimates of shortening in the Jamaica Passage and in the Gulf of Gonâve indicate an increase of the compressional component of deformation toward the east, which nonetheless remains very small compared to that inferred from block modeling based on GPS measurements.

  8. The GEORED and Plate Boundary Observatory Engineer Exchange Program

    Science.gov (United States)

    Feaux, K.; Mora-Paez, H.

    2007-05-01

    In early 2007, the Colombian Institute of Geology and Mining - INGEOMINAS initiated GEORED (Geodesia: Red de Estudios de Deformación) in order to increase the knowledge of the geodynamics of northwestern South America. GEORED is an essential tool for determining crustal deformation and is primary in the analysis of inter- plate and intraplate deformation and the present seismic cycle. Some of the objectives of the project are to improve the technical, scientific, and operational capabilities of Colombian scientists regarding tectonic and volcanic deformation in Colombia, to implement a Colombian GPS permanent network for the study of geodynamics, with near real-time data retrieval and processing, and to establish a high precision geodetic reference frame for multipurpose activities within INGEOMINAS. Phase 1 of GEORED, which includes the installation of 30 permanent GPS stations in Colombia, will commence in early 2007. The Plate Boundary Observatory (PBO), part of the larger NSF-funded EarthScope project managed by UNAVCO, will study the three-dimensional strain field resulting from active plate boundary deformation across the Western United States. PBO is a large construction project involving the reconnaissance, permitting, installation, documentation, and maintenance of 875 permanent GPS stations scheduled for completion in September 2008. PBO is currently in the fourth year of the project, with over 550 GPS stations completed to date. INGEOMINAS recently became a member of the UNAVCO consortium. UNAVCO has been working with INGEOMINAS by providing technical support for the GEORED project relating to GPS receiver specifications. In the spirit of collaboration and outreach, INGEOMINAS and UNAVCO will begin an engineer exchange program starting in early summer 2007. The purpose of this outreach program is to provide a mechanism for the exchange of ideas relating to GPS station construction techniques, hardware designs, data communications, and data archiving

  9. Hidden Earthquake Potential in Plate Boundary Transition Zones

    Science.gov (United States)

    Furlong, Kevin P.; Herman, Matthew; Govers, Rob

    2017-04-01

    Plate boundaries can exhibit spatially abrupt changes in their long-term tectonic deformation (and associated kinematics) at triple junctions and other sites of changes in plate boundary structure. How earthquake behavior responds to these abrupt tectonic changes is unclear. The situation may be additionally obscured by the effects of superimposed deformational signals - juxtaposed short-term (earthquake cycle) kinematics may combine to produce a net deformational signal that does not reflect intuition about the actual strain accumulation in the region. Two examples of this effect are in the vicinity of the Mendocino triple junction (MTJ) along the west coast of North America, and at the southern end of the Hikurangi subduction zone, New Zealand. In the region immediately north of the MTJ, GPS-based observed crustal displacements (relative to North America (NAm)) are intermediate between Pacific and Juan de Fuca (JdF) motions. With distance north, these displacements rotate to become more aligned with JdF - NAm displacements, i.e. to motions expected along a coupled subduction interface. The deviation of GPS motions from the coupled subduction interface signal near the MTJ has been previously interpreted to reflect clock-wise rotation of a coastal, crustal block and/or reduced coupling at the southern Cascadia margin. The geologic record of crustal deformation near the MTJ reflects the combined effects of northward crustal shortening (on geologic time scales) associated with the MTJ Crustal Conveyor (Furlong and Govers, 1999) overprinted onto the subduction earthquake cycle signal. With this interpretation, the Cascadia subduction margin appears to be well-coupled along its entire length, consistent with paleo-seismic records of large earthquake ruptures extending to its southern limit. At the Hikurangi to Alpine Fault transition in New Zealand, plate interactions switch from subduction to oblique translation as a consequence of changes in lithospheric structure of

  10. Forces Between a Permanent Magnet and a Soft Magnetic Plate

    DEFF Research Database (Denmark)

    Beleggia, Marco; Vokoun, David; De Graef, Marc

    2012-01-01

    Forces between a hard/permanent magnet of arbitrary shape and an ideally soft magnetic plate in close proximity are derived analytically from the image method applied to magnetostatics. We found that the contact force, defined as the force required to detach the hard magnet from the plate......, coincides with that between two identical touching permanent magnets. Furthermore, if the hard and the soft magnets are displaced by some amount, their attraction equals that between two identical permanent magnets displaced by twice that amount. Experimental results are presented that validate...

  11. Controllability of a viscoelastic plate using one boundary control in displacement or bending

    OpenAIRE

    Pandolfi, L.

    2016-01-01

    In this paper we consider a viscoelastic plate (linear viscoelasticity of the Maxwell-Boltzmann type) and we compare its controllability properties with the (known) controllability of a purely elastic plate (the control acts on the boundary displacement or bending). By combining operator and moment methods, we prove that the viscoelastic plate inherits the controllability properties of the purely elastic plate.

  12. Heel strike detection using split force-plate treadmill.

    Science.gov (United States)

    Rouhani, Hossein; Abe, Masaki O; Nakazawa, Kimitaka; Popovic, Milos R; Masani, Kei

    2015-03-01

    A common source of error when detecting heel-strike moments utilizing split force-plate treadmills is unwillingly stepping on contra-lateral force-plate. In this study, we quantified this error when heel-strike was detected based on such erroneous data and compared three methods to investigate how well the heel-strikes and stride-intervals were detected with erroneous data. Eleven subjects walked on a split force-plate treadmill for more than 20min. We used 20N and 50% body-weight thresholds to detect the heel-strike moments (HS20N and HS50%, respectively). Besides, we used linear approximation to estimate the unaffected force profile from affected force-plate data, and subsequently to detect the heel-strike moments (HSest). We used heel-strike moments detected by a foot-switch as a reference to compare accuracy of HS20N, HS50% and HSest. HS20N and HSest detected heel-strike moments accurately for unaffected force-plate data (median(max) errors for all subjects: 9(23) and 9(37) ms) but HS50% showed significantly larger errors (52(74) ms). Unlike HS50% and HSest, HS20N was considerably affected by the affected force-plate data (23(68) ms). The error in stride-interval measurement was relatively small using any methods for unaffected force-plate data (3(7), 6(8), and 6(12) ms), while stride-interval errors were large for some subjects when using HS20N for affected data (6(175) ms). We concluded that unwillingly stepping on contra-lateral force-plate occurred a few percent and up to 37.7% of all strides (median: 12.9%). Our proposed method (HSest) robustly showed small errors for heel-strike detection and stride-interval calculation consistently among subjects, while HS50% and HS20N showed large errors depending on subjects.

  13. A feedback control system for vibration of magnetostrictive plate subjected to follower force using sinusoidal shear

    Directory of Open Access Journals (Sweden)

    A. Ghorbanpour Arani

    2016-03-01

    Full Text Available In this research, the vibrational behavior of magnetostrictive plate (MsP as a smart component is studied. The plate is subjected to an external follower force and a magnetic field in which the vibration response of MsP has been investigated for both loading combinations. The velocity feedback gain parameter is evaluated to study the effect of magnetic field which is generated by the coil. Sinusoidal shear deformation theory is utilized due to its accuracy of polynomial function with respect to other plate theories. Equations of motion are derived using Hamilton’s principle and solved by differential quadrature method (DQM considering general boundary conditions. The effects of aspect ratio, thickness ratio, follower force and velocity feedback gain are investigated on the frequency response of MsP. Results indicate that magneto-mechanical coupling in MsM helps to control vibrational behaviors of systems such as electro-hydraulic actuator, wireless linear Motors and sensors.

  14. Nonlinear Forced Vibration Analysis for Thin Rectangular Plate on Nonlinear Elastic Foundation

    Directory of Open Access Journals (Sweden)

    Zhong Zhengqiang

    2013-02-01

    Full Text Available Nonlinear forced vibration is analyzed for thin rectangular plate with four free edges on nonlinear elastic foundation. Based on Hamilton variation principle, equations of nonlinear vibration motion for thin rectangular plate under harmonic loads on nonlinear elastic foundation are established. In the case of four free edges, viable expressions of trial functions for this specification are proposed, satisfying all boundary conditions. Then, equations are transformed to a system of nonlinear algebraic equations by using Galerkin method and are solved by using harmonic balance method. In the analysis of numerical computations, the effect on the amplitude-frequency characteristic curve due to change of the structural parameters of plate, parameters of foundation and parameters of excitation force are discussed.

  15. Calculating forces on thin flat plates with incomplete vorticity-field data

    Science.gov (United States)

    Limacher, Eric; Morton, Chris; Wood, David

    2016-11-01

    Optical experimental techniques such as particle image velocimetry (PIV) permit detailed quantification of velocities in the wakes of bluff bodies. Patterns in the wake development are significant to force generation, but it is not trivial to quantitatively relate changes in the wake to changes in measured forces. Key difficulties in this regard include: (i) accurate quantification of velocities close to the body, and (ii) the effect of missing velocity or vorticity data in regions where optical access is obscured. In the present work, we consider force formulations based on the vorticity field, wherein mathematical manipulation eliminates the need for accurate near-body velocity information. Attention is restricted to nominally two dimensional problems, namely (i) a linearly accelerating flat plate, investigated using PIV in a water tunnel, and (ii) a pitching plate in a freestream flow, as investigated numerically by Wang & Eldredge (2013). The effect of missing vorticity data on the pressure side of the plate has a significant impact on the calculation of force for the pitching plate test case. Fortunately, if the vorticity on the pressure side remains confined to a thin boundary layer, simple corrections can be applied to recover a force estimate.

  16. Stability and coherent structures of the asymptotic suction boundary layer over a heated plate

    CERN Document Server

    Zammert, Stefan; Eckhardt, Bruno

    2016-01-01

    The asymptotic suction boundary layer (ASBL) is a parallel shear flow that becomes turbulent in a bypass transition in parameter regions where the laminar profile is stable. We here add a temperature gradient perpendicular to the plate and explore the interaction between convection and shear in determining the transition. We find that the laminar state becomes unstable in a subcritical bifurcation and that the critical Rayleigh number and wave number depend strongly on the Prandtl number. We also track several secondary bifurcations and identify states that are localized in two directions, showing different symmetries. In the subcritical regime, transient turbulent states which are connected to exact coherent states and follow the same transition scenario as found in linearly stable shear flows are identified and analyzed. The study extends the bypass transition scenario from shear flows to thermal boundary layers and shows the intricate interactions between thermal and shear forces in determining critical po...

  17. A force plate based method for the calibration of force/torque sensors

    NARCIS (Netherlands)

    Faber, Gert S.; Chang, Chien-Chi; Kingma, Idsart; Schepers, H. Martin; Herber, Sebastiaan; Veltink, Peter H.; Dennerlein, Jack T.

    2012-01-01

    This study describes a novel calibration method for six-degrees-of-freedom force/torque sensors (FTsensors) using a pre-calibrated force plate (FP) as a reference measuring device. In this calibration method, the FTsensor is rigidly connected to a FP and force/torque data are synchronously recorded

  18. Initial-boundary value problems for a class of nonlinear thermoelastic plate equations

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Wen; Rong Xiao-Liang; Wu Run-Heng

    2009-01-01

    This paper studies initial-boundary value problems for a class of nonlinear thermoelastic plate equations. Under some certain initial data and boundary conditions,it obtains an existence and uniqueness theorem of global weak solutions of the nonlinear thermoelstic plate equations,by means of the Galerkin method. Moreover,it also proves the existence of strong and classical solutions.

  19. Accommodation of collisional shortening along the Alpine plate boundary : plate kinematics vs rheological controls

    Science.gov (United States)

    Rosenberg, Claudio; Bellahsen, Nicolas

    2016-04-01

    The style of collision in the Alps varies along strike, reflecting different amounts and different modes of accommodation of collisional shortening. These differences control the patterns of exhumation during collision. Whereas the western Alps largely consist of a metamorphic complex formed during subduction and largely exhumed before the initiation of collision, the subduction nappe-stack of the Central and the Eastern Alps is strongly overprinted by collisional shortening and by Barrovian metamorphism. Based on compiled and new data we estimate amounts of collisional shortening along the strike of the chain and set it in relationship to the geometry of the collisional prism. The western Alpine collisional structures form a very large (in map view), but moderately shortened wedge, terminating in front of a poorly developed Molasse basin. Shortening of this wedge was mainly localized along its external parts, resulting in accretion of basement and cover units thrusted towards the foreland. Back-folding and back-thrusting are barely developed and no shortening takes place in the upper, Adriatic plate. In the Central Alps, the amount of collisional shortening is larger and it is distributed both in the lower and in the upper plate. The collisional prism is bivergent and partitioning of the amount of shortening between the upper and lower plates varies along strike, being most probably controlled by rheological, heterogeneities. The thickened accreted lower plate is strongly affected by Barrovian metamorphism where shortening is largest and localized within a confined area. A deep Molasse basin developed in front of the prism. In the Eastern Alps collisional kinematics vary from east to west, with orogen-parallel displacements dominating in the east and orogen-perpendicular ones in the West, where they culminate in the structural and metamorphic dome of the Tauern Window. Nowhere else in the Alps collisional shortening is so strongly localized in one and the same

  20. 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

  1. The Plate Boundary Observatory: Data Management Progress and Highlights

    Science.gov (United States)

    Anderson, G.; Blackman, B.; Eakins, J.; Hodgkinson, K.; Matykiewicz, J.; Boler, F.; Beldyk, M.; Henderson, B.; Hoyt, B.; Lee, E.; Persson, E.; Smith, J.; Torrez, D.; Wright, J.; Jackson, M.; Meertens, 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, as well as manage data for 209 previously existing continuous GPS stations and one laser strainmeter through the PBO Nucleus project and 11 GPS stations installed by the USArray segment of EarthScope. As of 1 September 2007, UNAVCO had completed 680 PBO GPS stations and had upgraded 89% of the planned PBO Nucleus stations. Most of these stations return data to the UNAVCO Boulder Network Operations Center (NOC) on a daily basis, with about 40 stations returning data on an hourly basis. Overall, the combined PBO and Nucleus network has now provided almost 350 GB of raw standard rate data, which are routinely processed by the PBO GPS Analysis Centers, at Central Washington University and the New Mexico Institute of Mining and Technology, and the PBO GPS Analysis Center Coordinator at MIT. These groups create a range of GPS products, including station position time series, GPS velocity vectors, and related information. As of September 2007, these centers processed data on a daily basis from about 920 stations; typical position uncertainties are under 1.5 mm horizontally and 4 mm vertically. All PBO GPS data products are archived at and available from the UNAVCO Facility, with a second archive at the IRIS Data Management Center (DMC). All these products may be accessed via the PBO web page at http://pboweb.unavco.org/gps_data. As part of PBO, UNAVCO will also install and operate the largest borehole seismic and strainmeter networks in North America, as well as tiltmeters and laser strainmeters. As of September 2007, 41 PBO borehole stations

  2. Elastoplastic analysis for infinite plate with centric crack loaded by two pairs of point shear forces

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-ping; LING Tong-hua

    2005-01-01

    The near crack line analysis method was used to investigate a crack loaded by two pairs of point shear forces in an infinite plate in an elastic-perfectly plastic solid, and the analytical solution was obtained. The solutions include: the unit normal vector of the elastic-plastic boundary near the crack line, the elastic-plastic stress fields near crack line, law that the length of the plastic zone along the crack line is varied with an external loads, and the bearing capacity of an infinite plate with a center crack loaded by two pairs of point shear forces. The results are sufficiently precise near the crack line because the assumptions of the small scale yielding theory have not been made and no other assumption have been taken.

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

    Institute of Scientific and Technical Information of China (English)

    Krishnendu Bhattacharyya; Swati Mukhopadhyay; G.C.Layek

    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.%@@ 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.

  4. Hydrological Effects in the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Meertens, C.; Wahr, J.; Borsa, A.; Jackson, M.; Wahr, A.

    2008-12-01

    The dense network of 1,100 continuously operating GPS stations in the Plate Boundary Observatory (PBO) is providing high quality position time series. Data are processed by PBO Analysis Centers at the New Mexico Institute of Mining and Technology and at Central Washington University. The results are combined by the Analysis Center Coordinator at the Massachusetts Institute of Technology and are made available from the UNAVCO Data Center in Boulder. Analysis software of Langbein, 2008, was used to estimate secular trends and annual variations in the time series. The results were interpreted in terms of hydrological loading and poroelastic effects, from both natural and anthropogenic changes in water storage. The effects of monument stability were also considered. The density of PBO observations allows for the identification of spatial patterns that appear coherent over relatively broad areas. Vertical annual signals of 8-10 mm peak-to-peak amplitude are evident at stations in the mountains of northern and central California and southern Oregon showing peak uplift in October and are correlated to hydrological loading. The vertical elastic loading signal, calculated from the 0.25 by 0.25 degree community Noah land-surface model, fits the annual signal well and appears also to model the secular trends, although the time duration of ~3 years is still limited. In contrast to mountainous regions, stations in the valleys of California show greater spatial variability ranging from stations with almost no detectable annual signal to stations with very large, 20-30 mm, amplitudes with peak uplift in March. The vertical signals are temporally correlated to ground-water variations caused by pumping for agricultural irrigation and likely are caused by poroelastic effects in the sediments rather than loading. Annual vertical signals in southern California, where not obviously influenced from localized ground-water fluctuations, are small with ~2 mm amplitude and may be due to

  5. Plate boundaries and evolution of the Solomon Sea region

    Science.gov (United States)

    Honza, E.; Davies, H. L.; Keene, J. B.; Tiffin, D. L.

    1987-09-01

    The Solomon Sea Plate was widely developed during late Oligocene, separating the proto-West Melanesian Arc from the proto-Trobriand Arc. Spreading in the Bismarck Sea and in the Woodlark Basin resulted from interaction between the Pacific and Australian Plates, specifically from the collision of the proto-West Melanesian Arc with north New Guinea, which occurred after arc reversal. This model explains the extensive Miocene, Pliocene, and Quaternary volcanism of the Papua New Guinea mainland as it related to southward subduction of the Trobriand Trough. Our interpreted plate motions are concordant with the geological evidence onshore and also with complex tectonic features in the Solomon Sea Basin Region.

  6. Active faulting and transpression tectonics along the plate boundary in North Africa

    OpenAIRE

    Mustapha Meghraoui; Silvia Pondrelli

    2012-01-01

    International audience; We present a synthesis of the active tectonics of the northern Atlas Mountains , and suggest a kinematic model of transpression and block rotation that illustrates the mechanics of this section of the Africa–Eurasia plate boundary. Neotectonic structures and significant shallow seismicity (with Mw >5.0) indicate that coeval E-W-trending, right-lateral faulting and NE-SW, thrust-related folding result from oblique convergence at the plate boundary, which forms a transpr...

  7. Analyzing excitation forces acting on a plate based on measured acoustic pressure.

    Science.gov (United States)

    Wu, Sean F; Zhou, Pan

    2016-07-01

    This paper presents a theoretical study on "seeing" through an elastic structure to uncover the root cause of sound and vibration by using nearfield acoustical holography (NAH) and normal modes expansion. This approach is of generality because vibro-acoustic responses on the surface of a vibrating structure can always be reconstructed, exactly or approximately. With these vibro-acoustic responses, excitation forces acting on the structure can always be determined, analytically or numerically, given any set of boundary conditions. As an example, the explicit formulations for reconstructing time-harmonic excitation forces, including point, line and surface forces, and their arbitrary combinations acting on a rectangular thin plate in vacuum mounted on an infinite baffle are presented. The reason for choosing this example is that the analytic solutions to vibro-acoustic responses are available, and in-depth analyses of results are possible. Results demonstrate that this approach allows one to identify excitation forces based on measured acoustic pressures and reveal their characteristics such as locations, types and amplitudes, as if one could "see" excitation forces acting behind the plate based on acoustic pressure measured on the opposite side. This approach is extendable to general elastic structures, except that in such circumstance numerical results must be sought.

  8. 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

  9. Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

    Science.gov (United States)

    Balakumar, P.; King, Rudolph A.; Chou, Amanda; Owens, Lewis R.; Kegerise, Michael A.

    2016-01-01

    Supersonic boundary-layer receptivity to freestream acoustic disturbances is investigated by solving the Navier-Stokes equations for Mach 3.5 flow over a sharp flat plate and a 7-deg half-angle cone. The freestream disturbances are generated from a wavy wall placed at the nozzle wall. The freestream acoustic disturbances radiated by the wavy wall are obtained by solving the linearized Euler equations. The results for the flat plate show that instability modes are generated at all the incident angles ranging from zero to highly oblique. However, the receptivity coefficient decreases by about 20 times when the incident angle increases from zero to a highly oblique angle of 68 degrees. The results for the cone show that no instability modes are generated when the acoustic disturbances impinge the cone obliquely. The results show that the perturbations generated inside the boundary layer by the acoustic disturbances are the response of the boundary layer to the external forcing. The amplitude of the forced disturbances inside the boundary layer are about 2.5 times larger than the incoming field for zero azimuthal wavenumber and they are about 1.5 times for large azimuthal wavenumbers.

  10. DUAL RECIPROCITY BOUNDARY ELEMENT METHOD FOR FLEXURAL WAVES IN THIN PLATE WITH CUTOUT

    Institute of Scientific and Technical Information of China (English)

    GAO Suo-wen; WANG Yue-sheng; ZHANG Zi-mao; MA Xing-rui

    2005-01-01

    The theoretical analysis and numerical calculation of scattering of elastic waves and dynamic stress concentrations in the thin plate with the cutout was studied using dual reciprocity boundary element method (DRM). Based on the work equivalent law, the dual reciprocity boundary integral equations for flexural waves in the thin plate were established using static fundamental solution. As illustration, numerical results for the dynamic stress concentration factors in the thin plate with a circular hole are given.The results obtained demonstrate good agreement with other reported results and show high accuracy.

  11. Relationship between outer forearc subsidence and plate boundary kinematics along the Northeast Japan convergent margin

    Science.gov (United States)

    Regalla, Christine; Fisher, Donald M.; Kirby, Eric; Furlong, Kevin P.

    2013-12-01

    Tectonic erosion along convergent plate boundaries, whereby removal of upper plate material along the subduction zone interface drives kilometer-scale outer forearc subsidence, has been purported to explain the evolution of nearly half the world's subduction margins, including part of the history of northeast Japan. Here, we evaluate the role of plate boundary dynamics in driving forearc subsidence in northeastern Japan. A synthesis of newly updated analyses of outer forearc subsidence, the timing and kinematics of upper plate deformation, and the history of plate convergence along the Japan trench demonstrate that the onset of rapid fore-arc tectonic subsidence is contemporaneous with upper plate extension during the opening of the Sea of Japan and with an acceleration in convergence rate at the trench. In Plio-Quaternary time, relative uplift of the outer forearc is contemporaneous with contraction across the arc and a decrease in plate convergence rate. The coincidence of these changes across the forearc, arc, backarc system appears to require an explanation at the scale of the entire plate boundary. Similar observations along other western Pacific margins suggest that correlations between forearc subsidence and major changes in plate kinematics are the rule, rather than the exception. We suggest that a significant component of forearc subsidence at the northeast Japan margin is not the consequence of basal tectonic erosion, but instead reflects dynamic changes in plate boundary geometry driven by temporal variations in plate kinematics. If correct, this model requires a reconsideration of the mass balance and crustal recycling of continental crust at nonaccretionary margins.

  12. Forced wave motion with internal and boundary damping.

    Science.gov (United States)

    Louw, Tobias; Whitney, Scott; Subramanian, Anu; Viljoen, Hendrik

    2012-01-01

    A d'Alembert-based solution of forced wave motion with internal and boundary damping is presented with the specific intention of investigating the transient response. The dynamic boundary condition is a convenient method to model the absorption and reflection effects of an interface without considering coupled PDE's. Problems with boundary condition of the form [Formula: see text] are not self-adjoint which greatly complicates solution by spectral analysis. However, exact solutions are found with d'Alembert's method. Solutions are also derived for a time-harmonically forced problem with internal damping and are used to investigate the effect of ultrasound in a bioreactor, particularly the amount of energy delivered to cultured cells. The concise form of the solution simplifies the analysis of acoustic field problems.

  13. Stress and mixed boundary conditions for two-dimensional dodecagonal quasi-crystal plates

    Indian Academy of Sciences (India)

    Yan Gao; Si-Peng Xu; Bao-Sheng Zhao

    2007-05-01

    For plate bending and stretching problems in two-dimensional (2D) dodecagonal quasi-crystal (QC) media, the reciprocal theorem and the general solution for QCs are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all order. The method developed by Gregory and Wan is used to generate necessary conditions which the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the plate; these decaying state conditions are obtained explicitly for axisymmetric bending and stretching of a circular plate when stress or mixed conditions are imposed on the plate edge. They are then used for the correct formulation of boundary conditions for the interior solution. For the stress data, our boundary conditions coincide with those obtained in conventional forms of plate theories. More importantly, appropriate boundary conditions with a set of mixed edge-data are obtained for the first time. Furthermore, the corresponding necessary conditions for transversely isotropic elastic plate are obtained directly, and their isotropic elastic counterparts are also obtained.

  14. Upper boundary of the Pacific plate subducting beneath Hokkaido, Japan, estimated from ScSp phase

    OpenAIRE

    Osada, Kinue; Yoshizawa, Kazunori; YOMOGIDA, Kiyoshi

    2010-01-01

    Three-dimensional geometry of the upper boundary of the Pacific plate subducting beneath Hokkaido, Japan, was obtained using the ScSp phase: the phase converted from ScS (S wave reflected at the core-mantle boundary) to P wave at the plate boundary. Taking the advantage of a dense seismic network, "Hi-net", recently deployed across the Japanese islands, we applied several seismic array analyses to the recorded waveform data for a large nearby deep earthquake, in order to enhance very weak ScS...

  15. New method for solving the bending problem of rectangular plates with mixed boundary conditions

    Directory of Open Access Journals (Sweden)

    Liu Xin Min

    2016-01-01

    Full Text Available A new method is used to solve the rectangular plate bending problem with mixed boundary conditions. The method overcomes the complicated derivation of the classical solution by Fourth-order differential problem into integrating question. Under uniform loading rectangular plate bending problem with one side fixed the opposite side half simply supported half fixed the other two sides free rectangular plate, one side simply supported the opposite side half simply supported half fixed the other two sides free rectangular plate is systematically solved. According to the actual boundary conditions of the rectangular plate, the corresponding characteristic equation can easily be set up. It is presented deflection curve equation and the numerical calculation. By compared the results of the equation to the finite element program, we are able to demonstrate the correctness of the method. So the method not only has certain theoretical value, but also can be directly applied to engineering practice.

  16. The Cause of the Republic Day Earthquake of India: Intraplate or Plate Boundary Process?

    Science.gov (United States)

    Li, Q.

    2001-12-01

    The Mw 7.6 Republic Day (1/26/2001) earthquake of India killed at least 14,000 people and destroyed tens of thousands of homes. The cause of this earthquake and other historic earthquakes in the surrounding region, all thrust faults with roughly N-S compression, has been the subject of intensive debate. Some workers argued that this earthquake, located ~400 km from the plate boundary, is an intraplate event that may bear important implications for other intraplate earthquakes such as those in the New Madrid seismic zone. Others, however, recognize the diffuse plate boundary in western India and regard this earthquake as part of the plate boundary activity. We have developed a viscoelastic finite element model to address the question of why this and other historic earthquakes concentrated in this part of the India plate. The computer model includes relevant boundary conditions and first-order rheologic variations as indicated by geological and seismic data. We calculated the stresses within the India plate using displacement boundary conditions as indicated by the GPS data and compared the predicted stresses with the theoretical crustal strengths. Our results indicate that the change of plate boundary conditions (from transform fault along the Owen Fracture zone in the India ocean to continental thrusting and shearing along northwestern India) causes stress to accumulate in a broad zone near the junction of the Indian, the Arabian, and the Eurasian plates. Crustal weakening by diffuse seismicity along the northwestern Indian plate boundary may cause further inland migration of stress accumulation. With additional factors, including the contrasts of the crustal strength between the continental and oceanic Indian plate, the presence of the Kachchh rift zone, and the pronounced thinning of the lithosphere in this region as indicated by seismic tomography, the model predict an earthquake-prone belt extending hundreds of kilometers into the interior of the India plate

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

    NARCIS (Netherlands)

    Baes, M.|info:eu-repo/dai/nl/304824739

    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

  18. Experiments on forced convection form a horizontal heated plate in a packed bed of glass spheres

    Energy Technology Data Exchange (ETDEWEB)

    Renken, K.J. (Univ. of Wisconsin, Milwaukee (USA)); Poulikakos, D. (Univ. of Illinois, Chicago (USA))

    1989-02-01

    This paper presents an experimental investigation of boundary-layer forced convective heat transfer from a flat isothermal plate in a packed bed of spheres. Extensive experimental results are reported for the thermal boundary-layer thickness, the temperature field, and the local wall heat flux (represented by the local Nusselt number). Theoretical findings of previous investigations using the Darcy flow model as well as a general model for themomentum equation accouting for flow inertia and macroscopic shear wtih and without variable porosity are used to evaluate the theoretical models. Several trends are revealed regarding the conditions of validity of these flow models. Overall the general flow model including variable porosity appears to perform better, even through the need for serious improvements in modeling becomes apparent.

  19. Forced Convection Heat Transfer in Plate Channels Filled with Packed Beds or Sintered Porous Media

    Institute of Scientific and Technical Information of China (English)

    姜培学; 李勐; 任泽霈

    2002-01-01

    In the present work, forced convection heat transfer in plate channels filled with metallic or non-metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non-equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non-equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.

  20. Linking mantle dynamics, plate tectonics and surface processes in the active plate boundary zones of eastern New Guinea (Invited)

    Science.gov (United States)

    Baldwin, S.; Moucha, R.; Fitzgerald, P. G.; Hoke, G. D.; Bermudez, M. A.; Webb, L. E.; Braun, J.; Rowley, D. B.; Insel, N.; Abers, G. A.; Wallace, L. M.; Vervoort, J. D.

    2013-12-01

    Eastern New Guinea lies within the rapidly obliquely converging Australian (AUS)- Pacific (PAC) plate boundary zone and is characterized by transient plate boundaries, rapidly rotating microplates and a globally significant geoid high. As the AUS plate moved northward in the Cenozoic, its leading edge has been a zone of subduction and arc accretion. The variety of tectonic settings in this region permits assessment of the complex interplay among mantle dynamics, plate tectonics, and surface processes. Importantly, the timescale of tectonic events (e.g., subduction, (U)HP exhumation, seafloor spreading) are within the valid bounds of mantle convection models. A record of changes in bathymetry and topography are preserved in high standing mountain belts, exhumed extensional gneiss domes and core complexes, uplifted coral terraces, and marine sedimentary basins. Global seismic tomography models indicate accumulation of subducted slabs beneath eastern New Guinea at the bottom of the upper mantle (i.e., 250-300 km). Preliminary global-scale backward advected mantle convection models, driven by density inferred from joint seismic-geodynamic tomography models, exhibit large-scale flow associated with these subducted slab remnants and predict the timing and magnitude (up to 1500 m) of dynamic topography change (both subsidence and uplift) since the Oligocene. In this talk we will explore the effects of large-scale background mantle flow and plate tectonics on the evolution of topography and bathymetry in eastern New Guinea, and discuss possible mechanisms to explain basin subsidence and surface uplift in the region.

  1. Analytical Solutions to the Fundamental Frequency of Arbitrary Laminated Plates under Various Boundary Conditions

    Institute of Scientific and Technical Information of China (English)

    Yingqin Luo; Ming Hong; Yuan Liu

    2015-01-01

    In recent years, as the composite laminated plates are widely used in engineering practice such as aerospace, marine and building engineering, the vibration problem of the composite laminated plates is becoming more and more important. Frequency, especially the fundamental frequency, has been considered as an important factor in vibration problem. In this paper, a calculation method of the fundamental frequency of arbitrary laminated plates under various boundary conditions is proposed. The vibration differential equation of the laminated plates is established at the beginning of this paper and the frequency formulae of specialty orthotropic laminated plates under various boundary conditions and antisymmetric angle-ply laminated plates with simply-supported edges are investigated. They are proved to be correct. Simple algorithm of the fundamental frequency for multilayer antisymmetric and arbitrary laminated plates under various boundary conditions is studied by a series of typical examples. From the perspective of coupling, when the number of laminated plates layersN > 8–10, some coupling influence on the fundamental frequency can be neglected. It is reasonable to use specialty orthotropic laminated plates with the same thickness but less layers to calculate the corresponding fundamental frequency of laminated plates. Several examples are conducted to prove correctness of this conclusion. At the end of this paper, the influence of the selected number of layers of specialty orthotropic laminates on the fundamental frequency is investigated. The accuracy and complexity are determined by the number of layers. It is necessary to use proper number of layers of special orthotropic laminates with the same thickness to simulate the fundamental frequency in different boundary conditions.

  2. Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California

    Science.gov (United States)

    Ramsay, Joseph; Kohler, Monica D.; Davis, Paul M.; Wang, Xinguo; Holt, William; Weeraratne, Dayanthie S.

    2016-10-01

    SKS arrivals from ocean bottom seismometer (OBS) data from an offshore southern California deployment are analysed for shear wave splitting. The project involved 34 OBSs deployed for 12 months in a region extending up to 500 km west of the coastline into the oceanic Pacific plate. The measurement process consisted of removing the effects of anisotropy using a range of values for splitting fast directions and delay times to minimize energy along the transverse seismometer axis. Computed splitting parameters are unexpectedly similar to onland parameters, exhibiting WSW-ENE fast polarization directions and delays between 0.8 and 1.8 s, even for oceanic plate sites. This is the first SKS splitting study to extend across the entire boundary between the North America and Pacific plates, into the oceanic part of the Pacific plate. The splitting results show that the fast direction of anisotropy on the Pacific plate does not align with absolute plate motion (APM), and they extend the trend of anisotropy in southern California an additional 500 km west, well onto the oceanic Pacific plate. We model the finite strain and anisotropy within the asthenosphere associated with density-buoyancy driven mantle flow and the effects of APM. In the absence of plate motion effects, such buoyancy driven mantle flow would be NE-directed beneath the Pacific plate observations. The best-fit patterns of mantle flow are inferred from the tomography-based models that show primary influences from foundering higher-density zones associated with the history of subduction beneath North America. The new offshore SKS measurements, when combined with measurements onshore within the plate boundary zone, indicate that dramatic lateral variations in density-driven upper-mantle flow are required from offshore California into the plate boundary zone in California and western Basin and Range.

  3. Plate boundaries in the Woodlark Basin and Solomon Sea Region, Papua New Guinea

    Science.gov (United States)

    Goodliffe, A. M.; Cameron, M.

    2009-12-01

    The Solomon Sea and Woodlark Basin region of eastern Papua New Guinea is a tectonically complex region between the obliquely converging Pacific and Australian plates. Despite numerous marine geophysical surveys in the region, the exact nature of the tectonic boundaries between the Solomon Sea and the Woodlark Basin remains controversial. Marine geophysical data collected in the last decade provides additional insight into this region and clearly defines the boundaries of the Solomon Sea, Trobriand, Woodlark, and Australian plates. Multibeam bathymetry data collected in 2004 along the Trobriand Trough, together with seismic profiles across the trough, show a prominent deformation front in the trench that defines the southern boundary of the Solomon Sea plate. Petrologic data from volcanoes to the south of this boundary indicate that they have a subduction affinity. Heat flow profiles to the south of the plate boundary show a clear subduction signature. At the eastern termination of the Trobriand Trough the plate boundary forms a triple junction with the NE-SW trending Nubaru strike-slip fault. To the NE this major fault separates the Solomon Sea plate from the Woodlark plate. The morphology of this fault and a CMT solution indicate that it is right-lateral. To the SW the Nubaru strike-slip fault passes to the south of the Trobriand Trough, forming the southern boundary of the Trobriand plate (with the Trobriand Trough as the northern boundary). Further west the trend of the strike slip fault becomes more ENE-WSW. A significant extension component is evident as the fault passes to the north of Egum Graben and meets the Woodlark Basin spreading system at the current rifting to seafloor spreading transition directly to the east of Moresby Seamount. The revised tectonic model for this region has important implications for tectonic reconstructions that include an active rifting to spreading transition and prominent core complexes. In the past, models have assumed a

  4. A stochastic boundary forcing for dissipative particle dynamics

    Science.gov (United States)

    Altenhoff, Adrian M.; Walther, Jens H.; Koumoutsakos, Petros

    2007-07-01

    The method of dissipative particle dynamics (DPD) is an effective, coarse grained model of the hydrodynamics of complex fluids. DPD simulations of wall-bounded flows are however often associated with spurious fluctuations of the fluid properties near the wall. We present a novel stochastic boundary forcing for DPD simulations of wall-bounded flows, based on the identification of fluctuations in simulations of the corresponding homogeneous system at equilibrium. The present method is shown to enforce accurately the no-slip boundary condition, while minimizing spurious fluctuations of material properties, in a number of benchmark problems.

  5. Near-grain-boundary characterization by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pramanick, A.K., E-mail: pramanick@nmlindia.org [MST Division, National Metallurgical Laboratory, Jamshedpur 831007 (India); Sinha, A. [MST Division, National Metallurgical Laboratory, Jamshedpur 831007 (India); Sastry, G.V.S. [Centre of Advanced Study, Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Ghosh, R.N. [MST Division, National Metallurgical Laboratory, Jamshedpur 831007 (India)

    2009-05-15

    Characterization of near-grain boundary is carried out by atomic force microscopy (AFM). It has been observed to be the most suitable technique owing to its capability to investigate the surface at high resolution. Commercial purity-grade nickel processed under different conditions, viz., (i) cold-rolled and annealed and (ii) thermally etched condition without cold rolling, is considered in the present study. AFM crystallographic data match well with the standard data. Hence, it establishes two grain-boundary relations viz., plane matching and coincidence site lattice (CSL {Sigma}=9) relation for the two different sample conditions.

  6. Rupture across arc segment and plate boundaries in the 1 April 2007 Solomons earthquake

    Science.gov (United States)

    Taylor, Frederick W.; Briggs, Richard W.; Frohlich, Cliff; Brown, Abel; Hornbach, Matt; Papabatu, Alison K.; Meltzner, Aron J.; Billy, Douglas

    2008-04-01

    The largest earthquakes are generated in subduction zones, and the earthquake rupture typically extends for hundreds of kilometres along a single subducting plate. These ruptures often begin or end at structural boundaries on the overriding plate that are associated with the subduction of prominent bathymetric features of the downgoing plate. Here, we determine uplift and subsidence along shorelines for the 1 April 2007 moment magnitude MW 8.1 earthquake in the western Solomon Islands, using coral microatolls which provide precise measurements of vertical motions in locations where instrumental data are unavailable. We demonstrate that the 2007 earthquake ruptured across the subducting Simbo ridge transform and thus broke through a triple junction where the Australian and Woodlark plates subduct beneath the overriding Pacific plate. Previously, no known major megathrust rupture has involved two subducting plates. We conclude that this event illustrates the uncertainties of predicting the segmentation of subduction zone rupture on the basis of structural discontinuities.

  7. Repulsive Casimir force from fractional Neumann boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lim, S.C. [Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor (Malaysia)], E-mail: sclim@mmu.edu.my; Teo, L.P. [Faculty of Information Technology, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Department of Applied Mathematics, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan (Malaysia)], E-mail: lpteo@mmu.edu.my

    2009-08-17

    This Letter studies the finite temperature Casimir force acting on a rectangular piston associated with a massless fractional Klein-Gordon field at finite temperature. Dirichlet boundary conditions are imposed on the walls of a d-dimensional rectangular cavity, and a fractional Neumann condition is imposed on the piston that moves freely inside the cavity. The fractional Neumann condition gives an interpolation between the Dirichlet and Neumann conditions, where the Casimir force is known to be always attractive and always repulsive respectively. For the fractional Neumann boundary condition, the attractive or repulsive nature of the Casimir force is governed by the fractional order which takes values from zero (Dirichlet) to one (Neumann). When the fractional order is larger than 1/2, the Casimir force is always repulsive. For some fractional orders that are less than but close to 1/2, it is shown that the Casimir force can be either attractive or repulsive depending on the aspect ratio of the cavity and the temperature.

  8. Small Scale Forcing in a Turbulent Boundary Layer

    Science.gov (United States)

    Lorkowski, Thomas; Rathnasingham, Ruben; Breuer, Kenneth S.

    1996-11-01

    In order to understand the effect of small scale forcing on turbulent flows and its implications on control, an experimental investigation is made into the forcing of the inertial scales in the wall region of a turbulent boundary layer. A wall-mounted resonant actuator is used to produce a local vortical structure in the streamwise direction which is convected downstream by the boundary layer flow. The frequency associated with this structure is governed by the resonant frequency of the device and falls in the range of the inertial scales at the Reynolds number of the experiment (Re_θ = 2000). Hot-wire anemometry is used to map the velocity field at several stations downstream of the actuator. The signals are also conditioned to identify the effect of the actuator on different scales in the flow. Amplitude and modulation effects are also discussed. ^*Supported by ONR Grant N00014-92-J-1910.

  9. Spatio-temporal mapping of plate boundary faults in California using geodetic imaging

    Science.gov (United States)

    Donnellan, Andrea; Arrowsmith, Ramon; DeLong, Stephen B.

    2017-01-01

    The Pacific–North American plate boundary in California is composed of a 400-km-wide network of faults and zones of distributed deformation. Earthquakes, even large ones, can occur along individual or combinations of faults within the larger plate boundary system. While research often focuses on the primary and secondary faults, holistic study of the plate boundary is required to answer several fundamental questions. How do plate boundary motions partition across California faults? How do faults within the plate boundary interact during earthquakes? What fraction of strain accumulation is relieved aseismically and does this provide limits on fault rupture propagation? Geodetic imaging, broadly defined as measurement of crustal deformation and topography of the Earth’s surface, enables assessment of topographic characteristics and the spatio-temporal behavior of the Earth’s crust. We focus here on crustal deformation observed with continuous Global Positioning System (GPS) data and Interferometric Synthetic Aperture Radar (InSAR) from NASA’s airborne UAVSAR platform, and on high-resolution topography acquired from lidar and Structure from Motion (SfM) methods. Combined, these measurements are used to identify active structures, past ruptures, transient motions, and distribution of deformation. The observations inform estimates of the mechanical and geometric properties of faults. We discuss five areas in California as examples of different fault behavior, fault maturity and times within the earthquake cycle: the M6.0 2014 South Napa earthquake rupture, the San Jacinto fault, the creeping and locked Carrizo sections of the San Andreas fault, the Landers rupture in the Eastern California Shear Zone, and the convergence of the Eastern California Shear Zone and San Andreas fault in southern California. These examples indicate that distribution of crustal deformation can be measured using interferometric synthetic aperture radar (InSAR), Global Navigation

  10. Asymptotic analysis of the equations and boundary conditions of thermoelasticity of micropolar thin plates

    Directory of Open Access Journals (Sweden)

    Vardanyan S. A.

    2007-09-01

    Full Text Available In the framework of the asymmetrical momental micropolar theory in the present work the boundary value problem of thermal stresses in a three-dimensional thin plate with independent fields of displacements and rotations is studied on the basis of asymptotic method. Depending on the values of physical dimensionless constants of the material three applied two-dimensional theories of thermoelasticity of micropolar thin plate are constructed (theories with independent rotations, with constrained rotations and with small shift rigidity.

  11. Dynamic Stationary Response of Reinforced Plates by the Boundary Element Method

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Facundo Sanches

    2007-01-01

    Full Text Available A direct version of the boundary element method (BEM is developed to model the stationary dynamic response of reinforced plate structures, such as reinforced panels in buildings, automobiles, and airplanes. The dynamic stationary fundamental solutions of thin plates and plane stress state are used to transform the governing partial differential equations into boundary integral equations (BIEs. Two sets of uncoupled BIEs are formulated, respectively, for the in-plane state (membrane and for the out-of-plane state (bending. These uncoupled systems are joined to form a macro-element, in which membrane and bending effects are present. The association of these macro-elements is able to simulate thin-walled structures, including reinforced plate structures. In the present formulation, the BIE is discretized by continuous and/or discontinuous linear elements. Four displacement integral equations are written for every boundary node. Modal data, that is, natural frequencies and the corresponding mode shapes of reinforced plates, are obtained from information contained in the frequency response functions (FRFs. A specific example is presented to illustrate the versatility of the proposed methodology. Different configurations of the reinforcements are used to simulate simply supported and clamped boundary conditions for the plate structures. The procedure is validated by comparison with results determined by the finite element method (FEM.

  12. Shock Wave-Boundary Layer Interaction in Forced Shock Oscillations

    Institute of Scientific and Technical Information of China (English)

    Piotr Doerffer; Oskar Szulc; Franco Magagnato

    2003-01-01

    The flow in transonic diffusers as well as in supersonic air intakes becomes often unsteady due to shock wave boundary layer interaction. The oscillations may be induced by natural separation unsteadiness or may be forced by boundary conditions. Significant improvement of CFD tools, increase of computer resources as well as development of experimental methods have again.drawn the attention of researchers to this topic.To investigate the problem forced oscillations of transonic turbulent flow in asymmetric two-dimensional Laval nozzle were considered. A viscous, perfect gas flow, was numerically simulated using the Reynolds-averaged compressible Navier-Stokes solver SPARC, employing a two-equation, eddy viscosity, turbulence closure in the URANS approach.For time-dependent and stationary flow simulations, Mach numbers upstream of the shock between 1.2 and 1.4 were considered. Comparison of computed and experimental data for steady states generally gave acceptable agreement. In the case of forced oscillations, a harmonic pressure variation was prescribed at the exit plane resulting in shock wave motion. Excitation frequencies between 0 Hz and 1024 Hz were investigated at the same pressure amplitude.The main result of the work carried out is the relation between the amplitude of the shock wave motion and the excitation frequency in the investigated range. Increasing excitation frequency resulted in decreasing amplitude of the shock movement. At high frequencies a natural mode of shock oscillation (of small amplitude) was observed which is not sensitive to forced excitement.

  13. Lithospheric deformation in the Africa-Iberia plate boundary: Improved neotectonic modeling testing a basal-driven Alboran plate

    Science.gov (United States)

    Neres, M.; Carafa, M. M. C.; Fernandes, R. M. S.; Matias, L.; Duarte, J. C.; Barba, S.; Terrinha, P.

    2016-09-01

    We present an improved neotectonic numerical model of the complex NW Africa-SW Eurasia plate boundary segment that runs from west to east along the Gloria Fault up to the northern Algerian margin. We model the surface velocity field and the ongoing lithospheric deformation using the most recent version of the thin-shell code SHELLS and updated lithospheric model and fault map of the region. To check the presence versus the absence of an independently driven Alboran domain, we develop two alternative plate models: one does not include an Alboran plate; another includes it and determines the basal shear tractions necessary to drive it with known velocities. We also compare two alternative sets of Africa-Eurasia velocity boundary conditions, corresponding to geodetic and geological-scale averages of plate motion. Finally, we perform an extensive parametric study of fault friction coefficient, trench resistance, and velocities imposed in Alboran nodes. The final run comprises 5240 experiments, each scored to geodetic velocities (estimated for 250 stations and here provided), stress direction data, and seismic strain rates. The model with the least discrepancy to the data includes the Alboran plate driven by a basal WSW directed shear traction, slightly oblique to the westward direction of Alboran motion. We provide estimates of long-term strain rates and slip rates for the modeled faults, which can be useful for further hazard studies. Our results support that a mechanism additional to the Africa-Eurasia convergence is required to drive the Alboran domain, which can be related to subduction processes occurring within the mantle.

  14. Force sensor for chameleon and Casimir force experiments with parallel-plate configuration

    CERN Document Server

    Almasi, Attaallah; Iannuzzi, Davide; Sedmik, René I P

    2015-01-01

    The search for non-Newtonian forces has been pursued following many different paths. Recently it was suggested that hypothetical chameleon interactions, which might explain the mechanisms behind dark energy, could be detected in a high-precision force measurement. In such an experiment, interactions between parallel plates kept at constant separation could be measured as a function of the pressure of an ambient gas, thereby identifying chameleon interactions by their unique inverse dependence on the local mass density. During the past years we have been developing a new kind of setup complying with the high requirements of the proposed experiment. In this article we present the first and most important part of this setup -- the force sensor. We discuss its design, fabrication, and characterization. From the results of the latter we derive limits on chameleon interaction parameters that could be set by the forthcoming experiment. Finally, we describe the opportunity to use the same setup to measure Casimir for...

  15. Analysis of Blasius Equation for Flat-Plate Flow with Infinite Boundary Value

    DEFF Research Database (Denmark)

    Miansari, M. O.; Miansari, M. E.; Barari, Amin;

    2010-01-01

    This paper applies the homotopy perturbation method (HPM) to determine the well-known Blasius equation with infinite boundary value for Flat-plate Flow. We study here the possibility of reducing the momentum and continuity equations to ordinary differential equations by a similarity transformatio...

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

    NARCIS (Netherlands)

    van Benthem, S.A.C.|info:eu-repo/dai/nl/304833657; Govers, R.|info:eu-repo/dai/nl/108173836; Wortel, R.|info:eu-repo/dai/nl/068439202

    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

  17. Exact controllability of the Euler-Bernoulli plate with variable coefficients and simply supported boundary condition

    Directory of Open Access Journals (Sweden)

    Fengyan Yang

    2016-09-01

    Full Text Available This article studies the exact controllability of an Euler-Bernoulli plate equation with variable coefficients, subject to the simply supported boundary condition. By the Riemannian geometry approach, the duality method, the multiplier technique, and the compactness-uniqueness argument, we establish the corresponding observability inequality and obtain the exact controllability results.

  18. AN EFFECTIVE BOUNDARY ELEMENT METHOD FOR ANALYSIS OF CRACK PROBLEMS IN A PLANE ELASTIC PLATE

    Institute of Scientific and Technical Information of China (English)

    YAN Xiang-qiao

    2005-01-01

    A simple and effective boundary element method for stress intensity factor calculation for crack problems in a plane elastic plate is presented. The boundary element method consists of the constant displacement discontinuity element presented by Crouch and Starfield and the crack-tip displacement discontinuity elements proposed by YAN Xiangqiao. In the boundary element implementation the left or the right crack-tip displacement discontinuity element was placed locally at the corresponding left or right each crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. Test examples ( i. e. , a center crack in an infinite plate under tension, a circular hole and a crack in an infinite plate under tension) are included to illustrate that the numerical approach is very simple and accurate for stress intensity factor calculation of plane elasticity crack problems. In addition, specifically, the stress intensity factors of branching cracks emanating from a square hole in a rectangular plate under biaxial loads were analysed. These numerical results indicate the present numerical approach is very effective for calculating stress intensity factors of complex cracks in a 2-D finite body, and are used to reveal the effect of the biaxial loads and the cracked body geometry on stress intensity factors.

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

    NARCIS (Netherlands)

    van Benthem, S.A.C.|info:eu-repo/dai/nl/304833657; Govers, R.|info:eu-repo/dai/nl/108173836; Wortel, R.|info:eu-repo/dai/nl/068439202

    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 dr

  20. Scientific Advances from Paul Silver's Inspirational Leadership of the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Miller, M. M.; Calais, E.; Jackson, M. E.; Owen, S. E.; Segall, P.

    2009-12-01

    While major scientific endeavors and advances rely on the work and dedication of many, they are often made possible thanks to the passion and clear vision articulated by one or two leading scientists. Paul Silver was that leading visionary for EarthScope’s Plate Boundary Observatory. Paul Silver understood early on that the synergy of seismic and geodetic observations contained fundamental information on the coupled lithosphere-mantle system, the key to cracking the dynamics that underlies plate tectonics and continental deformation. This became a central theme of the Earthscope initiative, and Paul, a seismologist by training, became a tireless advocate for geodesy at all stages of the project - and for instrumentation over the broadest possible temporal bandwidth, from GPS geodesy to strainmeters. The presentation, given on behalf of UNAVCO and the UNAVCO community, will review and honor Paul's contributions to UNAVCO and the Plate Boundary Observatory science.

  1. Cocos Ridge Collision as a Driver for Plate Boundary Deformation in the Western Caribbean

    Science.gov (United States)

    La Femina, P. C.; Govers, R. M.; Geirsson, H.; Kobayashi, D.

    2011-12-01

    The subduction and collision of bathymetric highs can result in geodynamic changes along convergent plate boundaries, including intense upper plate deformation, increases in mechanical coupling and seismicity, migration and or cessation of volcanism and formation of forearc terranes. But how extensive can the deformation associated with these features be and what are the implications for the long-term formation and evolution of plate boundary zones? Plate boundary evolution and upper plate deformation in southern Central America associated with Cocos Ridge collision is well studied and indicates, 1) migration of the volcanic arc toward the backarc northwest of and cessation of volcanism directly inboard the ridge, 2) uplift of the Cordillera de Talamanca inboard the ridge, 3) shortening across the forearc Fila Costena fold and thrust belt, and 4) outer forearc uplift above and flanking the ridge. Recent geodynamical modeling of Cocos Ridge collision, combined with the results of kinematic block models for the Central American margin, suggests the ridge drives northwest-directed forearc motion from central Costa Rica northwest to the Cocos - Caribbean (Central American forearc block) - North America triple junction, greatly increasing the spatial scale of deformation. Upperplate deformation of the Central American margin to the southeast of the Cocos Ridge in Panama was not investigated in these models. We investigate the dynamics of Cocos Ridge collision along the entire Central American margin and the implications on plate boundary evolution with a new geodynamic model of ridge collision. Our model results are compared to a new GPS derived horizontal velocity field for Central America and preliminary results indicate that the Cocos Ridge drives the Panamanian isthmus into northern South America (i.e., the North Andes block).

  2. Propagation of rifting along the Arabia-Somalia Plate Boundary: Into Afar

    Science.gov (United States)

    Manighetti, I.; Tapponnier, P.; Gillot, P. Y.; Jacques, E.; Courtillot, V.; Armijo, R.; Ruegg, J. C.; King, G.

    1998-03-01

    northwestward. Concurrently, such lithospheric cracks are forced to jump northward, such that the plate boundary remains inside the regional N-S necking zone. Changes of obliquity between the directions of overall and local propagation may account for different segmentation patterns, a small angle promoting long, en échelon subrifts, and a high-angle, smaller, nested, "subrifts within subrifts." The propagation mechanism is thus similar, whether in oceanic or continental lithosphere, the principal change being the overall propagation path, here governed by thickness changes rather than by the geometry in map view as previously inferred for the rest of the Aden ridge. Finally, because the same mechanism has led rifting along the Red Sea to propagate southward and jump to the western edge of Afar, the Arabia-Somalia and Arabia-Nubia plate boundaries tips have missed each other and keep overlapping further, leading to strain transfer by large-scale bookshelf faulting.

  3. Discovering plate boundaries: Laboratory and classroom exercises using geodetic data to develop students' understanding of plate motion

    Science.gov (United States)

    Olds, S. E.

    2010-12-01

    To introduce the concept of plate boundaries, typical introductory geology exercises include students observing and plotting the location of earthquakes and volcanoes on a map to visually demarcate plate boundaries. Accompanying these exercises, students are often exposed to animations depicting the movement of Earth’s tectonic plates over time. Both of these teaching techniques are very useful for describing where the tectonics plates have been in the past, their shapes, and where the plates are now. With the integration of data from current geodetic techniques such as GPS, InSAR, LiDAR, students can learn that not only have the tectonic plates moved in the past, but they are moving, deforming, and changing shape right now. Additionally, GPS data can be visualized using time scales of days to weeks and on the scale of millimeters to centimeters per year. The familiar temporal and spatial scales of GPS data also help students understand that plate tectonics is a process that is happening in the present and can ease the transition to thinking about processes that are typically described using deep time, a very difficult concept for students to grasp. To provide a more robust learning environment, UNAVCO has been incorporating high-precision GPS data into free, place-based, data-rich learning modules for educators and students in introductory Earth science courses at secondary and undergraduate levels. These modules integrate new scientific discoveries related to crustal deformation and explore applications of GPS, LiDAR, and InSAR techniques to research. They also provide students with case studies highlighting the process of scientific discovery, providing context and meaning. Concurrent to these efforts, tools to visualize the inter-relationships of geophysical and geologic processes, structures, and measurements including high-precision GPS velocity data are an essential part of the learning materials. Among the suite of visualization tools that UNAVCO has made

  4. Transient-forced convection film boiling on an isothermal flat plate.

    Science.gov (United States)

    Nagendra, H. R.

    1972-01-01

    Development of a new approach for the solution of transient-forced convection film boiling on an isothermal flat plate using the boundary layer model. The similarity variables are used to convert the governing partial differential equations to ordinary ones. The results of numerical solutions of these ordinary equations indicate that the transient process can be classified as one-dimensional conduction, intermediate, and the steady-state regions. The time required for the one-dimensional conduction and the time necessary to attain a steady-state condition are obtained. The use of local similarity approximations for the intermediate regime facilitates prediction of complete boundary layer growth. Using the ratio of time at any instant to the steady-state time as abscissa, the curves representing the boundary layer growth can be merged into a single mean curve within 5%. Further, the analysis shows that the average rate of heat transfer during transient is 50 to 100% higher than those at steady state. The average rate of vapor convected away is 10 to 15% lower than at steady state while the average rate of accumulation to form the vapor layer is 1 to 14 times larger.

  5. Seismic evidence for sharp lithosphere-asthenosphere boundaries of oceanic plates.

    Science.gov (United States)

    Kawakatsu, Hitoshi; Kumar, Prakash; Takei, Yasuko; Shinohara, Masanao; Kanazawa, Toshihiko; Araki, Eiichiro; Suyehiro, Kiyoshi

    2009-04-24

    The mobility of the lithosphere over a weaker asthenosphere constitutes the essential element of plate tectonics, and thus the understanding of the processes at the lithosphere-asthenosphere boundary (LAB) is fundamental to understand how our planet works. It is especially so for oceanic plates because their relatively simple creation and evolution should enable easy elucidation of the LAB. Data from borehole broadband ocean bottom seismometers show that the LAB beneath the Pacific and Philippine Sea plates is sharp and age-dependent. The observed large shear wave velocity reduction at the LAB requires a partially molten asthenosphere consisting of horizontal melt-rich layers embedded in meltless mantle, which accounts for the large viscosity contrast at the LAB that facilitates horizontal plate motions.

  6. Discovering Plate Boundaries Update: Builds Content Knowledge and Models Inquiry-based Learning

    Science.gov (United States)

    Sawyer, D. S.; Pringle, M. S.; Henning, A. T.

    2009-12-01

    Discovering Plate Boundaries (DPB) is a jigsaw-structured classroom exercise in which students explore the fundamental datasets from which plate boundary processes were discovered. The exercise has been widely used in the past ten years as a classroom activity for students in fifth grade through high school, and for Earth Science major and general education courses in college. Perhaps more importantly, the exercise has been used extensively for professional development of in-service and pre-service K-12 science teachers, where it simultaneously builds content knowledge in plate boundary processes (including natural hazards), models an effective data-rich, inquiry-based pedagogy, and provides a set of lesson plans and materials which teachers can port directly into their own classroom (see Pringle, et al, this session for a specific example). DPB is based on 4 “specialty” data maps, 1) earthquake locations, 2) modern volcanic activity, 3) seafloor age, and 4) topography and bathymetry, plus a fifth map of (undifferentiated) plate boundary locations. The jigsaw is structured so that students are first split into one of the four “specialties,” then re-arranged into groups with each of the four specialties to describe the boundaries of a particular plate. We have taken the original DPB materials, used the latest digital data sets to update all the basic maps, and expanded the opportunities for further student and teacher learning. The earthquake maps now cover the recent period including the deadly Banda Aceh event. The topography/bathymetry map now has global coverage and uses ice-free elevations, which can, for example, extend to further inquiry about mantle viscosity and loading processes (why are significant portions of the bedrock surface of Greenland and Antarctica below sea level?). The volcanic activity map now differentiates volcano type and primary volcanic lithology, allowing a more elaborate understanding of volcanism at different plate boundaries

  7. A Development of Force Plate for Biomechanics Analysis of Standing and Walking

    Science.gov (United States)

    Wardoyo, S.; Hutajulu, P. T.; Togibasa, O.

    2016-08-01

    Force plates are known as an excellent teaching aid to demonstrate the kinematics and dynamics of motion and commonly used in biomechanics laboratories to measure ground forces involved in the motion of human. It is consist of a metal plate with sensors attached to give an electrical output proportional to the force on the plate. Moreover, force plates are useful for examining the kinetic characteristics of an athlete's movement. They provide information about the external forces involved in movement that can aid a coach or sports scientist to quantitatively evaluate the athlete's skill development. In this study, we develop our prototype of force plate with less than 100,- simply by using flexible force transducer attached inside rubber matt, in the form of square blocks (dimension: 250 mm × 150 mm × 10 mm), with maximum load up to 60 kg. The handmade force plate was tested by applying biomechanics analysis for standing and walking. The testing was done on Experimental Soccer Courses’ students at the Department of Physical Education, Health and Recreation, University of Cenderawasih. The design of the force plate system together with biomechanics analysis will be discussed.

  8. Forced convection on a heated horizontal flat plate with finite thermal conductivity in a non-Darcian porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Luna, N. [Direccion de Operacion Petrolera, Direccion General de Exploracion y Explotacion de Hidrocarburos, Secretaria de Energia, 03100 Mexico DF (Mexico); Mendez, F. [Facultad de Ingenieria, UNAM, 04510 Mexico DF (Mexico)

    2005-07-01

    The steady-state analysis of conjugated heat transfer process for the hydrodynamically developed forced convection flow on a heated flat plate embedded in a porous medium is studied. The governing equations for the fluid-saturated porous medium are solved analytically using the integral boundary layer approximation. This integral solution is coupled to the energy equation for the flat plate, where the longitudinal heat conduction effects are taken into account. The resulting equations are then reduced to an integro-differential equation which is solved by regular perturbation techniques and numerical methods. The analytical and numerical predictions for the temperature profile of the plate and appropriate local and average Nusselt numbers are plotted for finite values of the conduction parameter, {alpha}, which represents the presence of the longitudinal heat conduction effects. (authors)

  9. Lower plate deformation structures along the Costa Rica erosive plate boundary - results from IODP Expedition 344 (CRISP 2)

    Science.gov (United States)

    Brandstätter, Jennifer; Kurz, Walter; Micheuz, Peter; Krenn, Kurt

    2015-04-01

    1414 is located ~1 km seaward of the deformation front offshore the Osa Peninsula and Caño Island. Primary science goals at Site U1414 included characterization of the alteration state of the magmatic basement. Brittle structures within the incoming plate (sites U1380, U1414) are mineralized extensional fractures and shear fractures. The shear fractures mainly show a normal component of shear. Within the sedimentary sequence both types of fractures dip steeply (vertical to subvertical) and strike NNE-SSW. Deformation bands trend roughly ENE-WSW, sub-parallel to the trend of the Cocos ridge. Structures in the Cocos Ridge basalt mainly comprise mineralized veins at various orientations. A preferred orientation of strike directions was not observed. Some veins show straight boundaries, others are characterized by an irregular geometry characterized by brecciated wall rock clasts embedded within vein precipitates. The vein mineralization was analysed in detail by RAMAN spectroscopy. Precipitation conditions and fluid chemistry were analysed by fluid inclusions entrapped within vein minerals. Vein mineralizations mainly consist of carbonate (fibrous aragonite, calcite), chalcedony, and quartz. Vein mineralization is mainly characterized by zoned antitaxial growth of carbonate fibres including a suture along the central vein domains. Quartz is often characterized by fibre growth of crystals perpendicular to the vein boundaries, too. These zoned veins additinally have wall rock alteration seams consisting of clay minerals. The precipitation sequence basically indicates that fluid chemistry evolved from an CO2-rich towards a SiO2- rich fluid.

  10. Geological record of fluid flow and seismogenesis along an erosive subducting plate boundary.

    Science.gov (United States)

    Vannucchi, Paola; Remitti, Francesca; Bettelli, Giuseppe

    2008-02-07

    Tectonic erosion of the overriding plate by the downgoing slab is believed to occur at half the Earth's subduction zones. In situ investigation of the geological processes at active erosive margins is extremely difficult owing to the deep marine environment and the net loss of forearc crust to deeper levels in the subduction zone. Until now, a fossil erosive subduction channel-the shear zone marking the plate boundary-has not been recognized in the field, so that seismic observations have provided the only information on plate boundary processes at erosive margins. Here we show that a fossil erosive margin is preserved in the Northern Apennines of Italy. It formed during the Tertiary transition from oceanic subduction to continental collision, and was preserved by the late deactivation and fossilization of the plate boundary. The outcropping erosive subduction channel is approximately 500 m thick. It is representative of the first 5 km of depth, with its deeper portions reaching approximately 150 degrees C. The fossil zone records several surprises. Two décollements were simultaneously active at the top and base of the subduction channel. Both deeper basal erosion and near-surface frontal erosion occurred. At shallow depths extension was a key deformation component within this erosive convergent plate boundary, and slip occurred without an observable fluid pressure cycle. At depths greater than about 3 km a fluid cycle is clearly shown by the development of veins and the alternation of fast (co-seismic) and slow (inter-seismic) slip. In the deepest portions of the outcropping subduction channel, extension is finally overprinted by compressional structures. In modern subduction zones the onset of seismic activity is believed to occur at approximately 150 degrees C, but in the fossil channel the onset occurred at cooler palaeo-temperatures.

  11. Novel parallel plate condenser for single particle electrostatic force measurements in atomic force microscope

    KAUST Repository

    Kwek, Jin Wang

    2011-07-01

    A combination of small parallel plate condenser with Indium Tin Oxide (ITO) glass slides as electrodes and an atomic force microscope (AFM) is used to characterize the electrostatic behavior of single glass bead microparticles (105-150 μm) glued to the AFM cantilever. This novel setup allows measurements of the electrostatic forces acting on a particle in an applied electrical field to be performed in ambient air conditions. By varying the position of the microparticle between the electrodes and the strength of the applied electric field, the relative contributions of the particle net charge, induced and image charges were investigated. When the microparticle is positioned in the middle of the electrodes, the force acting on the microparticle was linear with the applied electric field and proportional to the microparticle net charge. At distances close to the bottom electrode, the force follows a parabolic relationship with the applied electric field reflecting the contributions of induced and image charges. The method can be used for the rapid evaluation of the charging and polarizability properties of the microparticle as well as an alternative to the conventional Faraday\\'s pail technique. © 2011 Elsevier B.V.

  12. Elastic-plastic analytical solution for centric crack loaded by two pairs of point shear forces in finite plate

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-ping; LING Tong-hua

    2006-01-01

    The near crack line analysis method was used to investigate a centric crack loaded by two pairs of point shear forces in a finite plate, and the analytical solution was obtained. The solution includes the unit normal vector of the elastic-plastic boundary near the crack line, the elastic-plastic stress fields near the crack line, the variations of the length of the plastic zone along the crack line with an external load, and the bearing capacity of a finite plate with a centric crack loaded by two pairs of point shear forces. The results are sufficiently precise near the crack line because the assumptions of small scale yielding theory have not been made and no other assumptions are taken.

  13. Structural vibration a uniform accurate solution for laminated beams, plates and shells with general boundary conditions

    CERN Document Server

    Jin, Guoyong; Su, Zhu

    2015-01-01

    This book develops a uniform accurate method which is capable of dealing with vibrations of laminated beams, plates and shells with arbitrary boundary conditions including classical boundaries, elastic supports and their combinations. It also provides numerous solutions for various configurations including various boundary conditions, laminated schemes, geometry and material parameters, which fill certain gaps in this area of reach and may serve as benchmark solutions for the readers. For each case, corresponding fundamental equations in the framework of classical and shear deformation theory are developed. Following the fundamental equations, numerous free vibration results are presented for various configurations including different boundary conditions, laminated sequences and geometry and material properties. The proposed method and corresponding formulations can be readily extended to static analysis.

  14. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    Directory of Open Access Journals (Sweden)

    Mohammed J Uddin

    Full Text Available Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  15. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    Science.gov (United States)

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  16. Global Models of Ridge-Push Force, Geoid, and Lithospheric Strength of Oceanic plates

    Science.gov (United States)

    Mahatsente, Rezene

    2017-08-01

    An understanding of the transmission of ridge-push related stresses in the interior of oceanic plates is important because ridge-push force is one of the principal forces driving plate motion. Here, I assess the transmission of ridge-push related stresses in oceanic plates by comparing the magnitude of the ridge-push force to the integrated strength of oceanic plates. The strength is determined based on plate cooling and rheological models. The strength analysis includes low-temperature plasticity (LTP) in the upper mantle and assumes a range of possible tectonic conditions and rheology in the plates. The ridge-push force has been derived from the thermal state of oceanic lithosphere, seafloor depth and crustal age data. The results of modeling show that the transmission of ridge-push related stresses in oceanic plates mainly depends on rheology and predominant tectonic conditions. If a lithosphere has dry rheology, the estimated strength is higher than the ridge-push force at all ages for compressional tectonics and at old ages (>75 Ma) for extension. Therefore, under such conditions, oceanic plates may not respond to ridge-push force by intraplate deformation. Instead, the plates may transmit the ridge-push related stress in their interior. For a wet rheology, however, the strength of young lithosphere (tectonics. In this case, the ridge-push related stress may dissipate in the interior of oceanic plates and diffuses by intraplate deformation. The state of stress within a plate depends on the balance of far-field and intraplate forces.

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

    Science.gov (United States)

    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.

  18. STRESS INTENSITY FACTORS FOR A FINITE PLATE WITH AN INCLINED CRACK BY BOUNDARY COLLOCATION

    Institute of Scientific and Technical Information of China (English)

    Xing Li; Xuemei You

    2005-01-01

    In this paper, we combine the Muskhelishvili's complex variable method and boundary collocation method, and choose a set of new stress function based on the stress boundary condition of crack surface,the higher precision and less computation are reached. This method is applied to calculating the stress intensity factor for a finite plate with an inclined crack. The influence of θ (the obliquity of crack) on the stress intensity factors, as well as the number of summation terms on the stress intensity factor are studied and graphically represented.

  19. Propagation of rifting along the Arabia-Somalia Plate Boundary: The Gulfs of Aden and Tadjoura

    Science.gov (United States)

    Manighetti, Isabelle; Tapponnier, Paul; Courtillot, Vincent; Gruszow, Sylvie; Gillot, Pierre-Yves

    1997-02-01

    The localization and propagation of rifting between Arabia and Somalia are investigated by assessing the deformation geometry and kinematics at different scales between the eastern Gulf of Aden and the Gulf of Tadjoura, using bathymetric, magnetic, seismological, and structural evidence. Large-scale, southwestward propagation of the Aden ridge, markedly oblique to the Arabia-Somalia relative motion vector, began about 30 Myr ago between the Error and Sharbithat ridges. It was an episodic process, with stages of rapid propagation, mostly at rates >10 cm/yr, interrupted by million year pauses on transverse discontinuities coinciding with rheological boundaries between different crustal provinces of the Arabia-Somalia plate. The longest pause was at the Shukra-El Sheik discontinuity (≈45°E), where the ridge tip stalled for ≈13 Myr, between ≈17 and ≈4 Ma. West of that discontinuity, rifting and spreading took place at an azimuth (≈N25°±10°E) and rate (1.2±0.3 cm/yr) different from those of the global Arabia-Somalia motion vector (≈N39°, ≈1.73 cm/yr), implying an additional component of movement (N65°±10°E, 0.7±0.2 cm/yr) due to rotation of the Danakil microplate. At Shukra-El Sheik, the typical oceanic ridge gives way to a narrow, WSW trending axial trough, resembling a large fissure across a shallow shelf. This trough is composed of about eight rift segments, which result from normal faulting and fissuring along N110°-N130°E trends. All the segments step to the left southwestward, mostly through oblique transfer zones with en échelon normal faults. Only two segments show clear, significant overlap. There is one clear transform, the Maskali fault, between the Obock and Tadjoura segments. The latter segment, which encroaches onland, is composed of two parallel subrifts (Iboli, Ambabbo) that propagated northwestward and formed in succession. The most recent, southwestern subrift (Ambabbo) represents the current tip of the Aden ridge. We propose

  20. Tectonic plate under a localized boundary stress: fitting of a zero-range solvable model

    CERN Document Server

    Petrova, L

    2008-01-01

    We suggest a method of fitting of a zero-range model of a tectonic plate under a boundary stress on the basis of comparison of the theoretical formulae for the corresponding eigenfunctions/eigenvalues with the results extraction under monitoring, in the remote zone, of non-random (regular) oscillations of the Earth with periods 0.2-6 hours, on the background seismic process, in case of low seismic activity. Observations of changes of the characteristics of the oscillations (frequency, amplitude and polarization) in course of time, together with the theoretical analysis of the fitted model, would enable us to localize the stressed zone on the boundary of the plate and estimate the risk of a powerful earthquake at the zone.

  1. World Stress Map Release 2005 - Stress orientations from single focal mechanisms at plate boundaries

    Science.gov (United States)

    Heidbach, O.; Barth, A.; Müller, B.; Reinecker, J.; Sperner, B.; Tingay, M.

    2005-12-01

    The World Stress Map (WSM) is a global compilation of data about recent tectonic stresses from a wide range of indicators (e.g. focal mechanisms, borehole breakouts). It is a valuable tool for the solution of numerous of technological and scientific problems. The orientation of the stress field, for instance, is a primary control on subsurface fluid flow and thus WSM data can be used to improve petroleum production or the efficiency of geothermal power stations. In scientific context, information on the stress state is essential for seismic hazard assessment. The WSM database release 2005 contains more than 14,000 data sets all classified according to a unified quality ranking. Thus, the comparability of data from different types of measurement is guaranteed. The database as well as guidelines and software for plotting stress maps are available free of charge from our website www.world-stress-map.org. Users can create their own stress map including their own stress data almost instantly with the CASMO (Create A Stress Map Online) web tool. Alternatively, users can download the software CASMI (Create A Stress Map Interactively) free of charge and produce their own stress maps. In the WSM 2005 release we refined the definition of so-called Possible Plate Boundary Events (PBE) for stress data from single focal mechanisms (FMS) considering that the orientations of these earthquakes might be rather controlled by the geometry of the plate boundary than by the stress field orientation. In general, it is assumed that numerous randomly oriented faults are present in the crust, so that earthquakes occur on faults optimally oriented relative to the regional stress field. In such a setting the principal axes of the moment tensor (P, B, T) provide good approximations for the principal stress orientations (σ_1, σ2, σ3). However, plate boundaries show a different mechanical behavior. They are characterized by faults with preferred orientations and presumably include major

  2. Near Continuum Velocity and Temperature Coupled Compressible Boundary Layer Flow over a Flat Plate

    Science.gov (United States)

    He, Xin; Cai, Chunpei

    2017-04-01

    The problem of a compressible gas flows over a flat plate with the velocity-slip and temperature-jump boundary conditions are being studied. The standard single- shooting method is applied to obtain the exact solutions for velocity and temperature profiles when the momentum and energy equations are weakly coupled. A double-shooting method is applied if these two equations are closely coupled. If the temperature affects the velocity directly, more significant velocity slip happens at locations closer to the plate's leading edge, and inflections on the velocity profiles appear, indicating flows may become unstable. As a consequence, the temperature-jump and velocity-slip boundary conditions may trigger earlier flow transitions from a laminar to a turbulent flow state.

  3. MHD Natural Convection with Convective Surface Boundary Condition over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad M. Rashidi

    2014-01-01

    Full Text Available We apply the one parameter continuous group method to investigate similarity solutions of magnetohydrodynamic (MHD heat and mass transfer flow of a steady viscous incompressible fluid over a flat plate. By using the one parameter group method, similarity transformations and corresponding similarity representations are presented. A convective boundary condition is applied instead of the usual boundary conditions of constant surface temperature or constant heat flux. In addition it is assumed that viscosity, thermal conductivity, and concentration diffusivity vary linearly. Our study indicates that a similarity solution is possible if the convective heat transfer related to the hot fluid on the lower surface of the plate is directly proportional to (x--1/2 where x- is the distance from the leading edge of the solid surface. Numerical solutions of the ordinary differential equations are obtained by the Keller Box method for different values of the controlling parameters associated with the problem.

  4. Geodetic observations in Iceland: divergent plate boundary influenced by a hotspot

    Science.gov (United States)

    Ofeigsson, Benedikt Gunnar; Hreinsdóttir, Sigrun; Sigmundsson, Freysteinn; Arnadottir, Thora; Vogfjord, Kristin; Geirsson, Halldor; Einarsson, Pall; Jonsson, Sigurjon; Villemin, Thierry; Fjalar Sigurdsson, Sigurdur; Roberts, Matthew; Sturkell, Erik; Lafemina, Peter C.; Bennett, Richard; Voelksen, Christof; Valsson, Gudmundur; Sigurdsson, Thorarinn

    2013-04-01

    The mid Atlantic ridge, separating the Eurasian and North American tectonic plates, is mostly buried below the Atlantic. There are, however, a few places where subaerial exposure of the mid-oceanic rift system allows geodetic observations of the deformation associated with the plate boundary. Iceland is the largest portion of the system emerged above sea level, a consequence of excessive volcanism caused by the interaction of a mantle plume with the mid-oceanic ridge. Iceland is therefore a unique site to study processes associated with divergent plate boundaries, and the effects of the plume-ridge interaction. A network of continuous GPS stations have been operating in Iceland since 1995 when the first station was installed in Reykjavik. Since then, stations have been added to the network at different points in time, with over 70 stations presently in operation. The network has been used e.g. for studies of deformation associated with the divergent plate boundary, micro-plate formation due to rift jumps, the plate-spreading deformation cycle associated with rifting episodes, strain rates and stress accumulation on transform zones connecting the ridge segments and deformation due to magmatic processes. In addition the GPS network is used in studies of the deformation associated with mass variations of Iceland's glaciers. The continuous GPS network serves as monitoring tool in Iceland, both for volcanic and seismic hazards but also as a research tool. In the recent Futurvolc project, which partly builds on EPOS, the data from the continuous GPS network along with data from the seismic network and InSAR observations, will serve as the main input in joint analyses of long and short term magma movements in volcanic regions. The establishment of the continuous GPS network in Iceland has provided an ideal tool to further increase our understanding of the geodynamic processes associated with divergent plate boundaries and plume-ridge interaction as well as establishing a

  5. A force plate based method for the calibration of force/torque sensors.

    Science.gov (United States)

    Faber, Gert S; Chang, Chien-Chi; Kingma, Idsart; Schepers, H Martin; Herber, Sebastiaan; Veltink, Peter H; Dennerlein, Jack T

    2012-04-30

    This study describes a novel calibration method for six-degrees-of-freedom force/torque sensors (FTsensors) using a pre-calibrated force plate (FP) as a reference measuring device. In this calibration method, the FTsensor is rigidly connected to a FP and force/torque data are synchronously recorded while a dynamic functional loading procedure is applied by the researcher. Based on these data an accurate calibration matrix for the FTsensor can easily be obtained via least-squares optimization. Using this calibration method, this study further investigated what loading methods are appropriate for the calibration of FTsensors intended for ambulatory measurement of ground reaction forces (GRFs). Seven different loading methods were compared (e.g., walking, pushing while standing on the FTsensor). Calibration matrices were calculated based on the raw data from the seven loading methods individually and all loading methods combined. Performance of these calibration matrices was subsequently compared in an in situ trial. During the in situ trial, five common work tasks (e.g., walking, manual lifting, pushing) were performed by an experimenter, while standing on the FP wearing a "ForceShoe" with two calibrated FTsensors attached to its sole. Root-mean-square differences (RMSDs) between the FTsensor and FP outcomes were calculated over all tasks. Using the calibration matrices based on all loading methods combined resulted in small RMSDs (GRF: <8 N, center of pressure: <2 mm). Using the calibration matrices based on "pushing against manual resistance" resulted in similar RMSDs, proving it to be the best single loading method.

  6. Numerical Solution of Membrane Forces for A Free-Free Floating Plate with Large Deflection

    Institute of Scientific and Technical Information of China (English)

    陈徐均; 崔维成; 宋皓; 汤雪峰

    2003-01-01

    Considering that the thickness of a pontoon-type very large floating structure (VLFS) is very small in comparison with the length and width, VLFS can be modeled as a thin plate. In theory, the displacements and the membrane forces of a plate with large deflection are all the functions of the second-order differentials of the Ariy stress function. With these characteristics considered, the Ariy stress function of a floating free-free plate is calculated by setting the virtual values of three of the corner points. The finite difference method is chosen to solve the problem. When the Ariy stress function of the plate is obtained, the membrane forces can easily be calculated. Comparisons between the forces induced by the membrane forces and by the fluid are considered. It is shown that the membrane forces can not be neglected in many cases.

  7. Unsteady Boundary-Layer Flow over Jerked Plate Moving in a Free Stream of Viscoelastic Fluid

    Directory of Open Access Journals (Sweden)

    Sufian Munawar

    2014-01-01

    Full Text Available This study aims to investigate the unsteady boundary-layer flow of a viscoelastic non-Newtonian fluid over a flat surface. The plate is suddenly jerked to move with uniform velocity in a uniform stream of non-Newtonian fluid. Purely analytic solution to governing nonlinear equation is obtained. The solution is highly accurate and valid for all values of the dimensionless time 0≤τ<∞. Flow properties of the viscoelastic fluid are discussed through graphs.

  8. Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

    OpenAIRE

    Silva, H. G; Bezzeghoud, M.; J. P. Rocha; P. F. Biagi; Tlemçani, M.; Rosa, R.N.; M. A. Salgueiro da Silva; Borges, J. F.; Caldeira, B.; Reis, A. H.; MANSO M.

    2011-01-01

    This paper presents a future research plan that aims to monitor Seismo-electromagnetic (SEM) phenomena in the western part of the Eurasia-Nubia plate boundary (WENP). This region has a significant tectonic activity [1] combined with relatively low electromagnetic noise levels and for that reason presents the possibility to perform high quality SEM measurements. Further, it is known that low-frequency [ultra (ULF), very (VLF), and low-frequencies (LF)] electromag- netic (EM) waves produce m...

  9. Locking, mass flux and topographic response at convergent plate boundaries - the Chilean case

    Science.gov (United States)

    Oncken, Onno

    2016-04-01

    On the long term, convergent plate boundaries have been shown to be controlled by either accretion/underplating or by subduction erosion. Vertical surface motion is coupled to convergence rate - typically with an uplift rate of the coastal area ranging from 0 to +50% of convergence rate in accretive systems, and -20 to +30% in erosive systems. Vertical kinematics, however, are not necessarily linked to horizontal strain mode, i.e. upper plate shortening or extension, in a simple way. This range of kinematic behaviors - as well as their acceleration where forearcs collide with oceanic ridges/plateau - is well expressed along the Chilean plate margin. Towards the short end of the time scale, deformation appears to exhibit a close correlation with the frictional properties and geodetic locking at the plate interface. Corroborating analogue experiments of strain accumulation during multiple earthquake cycles, forearc deformation and uplift focus above the downdip and updip end of seismic coupling and slip and are each related to a particular stage of the seismic cycle, but with opposite trends for both domains. Similarly, barriers separating locked domains along strike appear to accumulate most upper plate faulting interseismically. Hence, locking patters are reflected in topography. From the long-term memory contained in the forearc topography the relief of the Chilean forearc seems to reflect long term stability of the observed heterogeneity of locking at the plate interface. This has fundamental implications for spatial and temporal distribution of seismic hazard. Finally, the nature of locking at the plate interface controlling the above kinematic behavior appears to be strongly controlled by the degree of fluid overpressuring at the plate interface suggesting that the hydraulic system at the interface takes a key role for the forearc response.

  10. The restoring force on a dielectric in a parallel plate capacitor

    Science.gov (United States)

    Staunton, L. P.

    2014-09-01

    We investigate the restoring force on a dielectric slab being pulled from within the volume of a parallel plate capacitor connected to a battery. Using a conformal mapping to treat the fringing electric field exactly, we numerically obtain an expected Hooke's Law restoring force for small displacements, and a diminishing force for a displacement up to half the length of the dielectric.

  11. Long-term exhumation of landscapes along the Pacific-North American plate boundary as inferred from apatite (U-Th)/He and ArcGIS analyses

    OpenAIRE

    Buscher, Jamie Todd

    2007-01-01

    The Pacific-North American plate boundary is typified by transpression and convergence, yet the relationship between interplate deformation and long-term crustal shortening is not fully understood. The continuous belt of rugged topography that extends along the entire plate boundary is generally associated with oblique tectonic plate motion, strong interplate coupling, and terrane accretion, but relating plate boundary orogenesis to variations in plate geometry and behavior requires detailed ...

  12. 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.

  13. 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

  14. Correlation between retention force of experimental plates and viscosity of experimental fluids

    Directory of Open Access Journals (Sweden)

    Mladenović Dragan

    2011-01-01

    Full Text Available Introduction. Saliva viscosity plays a significant role in the biophysical segment of the total retention potential of total dentures. Objective. The aim of the paper was to establish the dependence of dynamic retention force of experimental plates on experimental fluid viscosity and especially time dependence of these parameters, following at the same time relative changes of the distance between the experimental plate and dentures support established by the dislocation of the experimental plate in both directions. Methods. For experimental verification we used an original device with the aim to enable in vivo simulation on the phantom made of the upper total denture prosthesis support and experimental plate. The experiment consisted of two parts. In the first part we determined the value of the dynamic retention force with plates without and with achieved ventilation effect. In the second part we determined time dependence of the dynamic retention force of experimental plates on the viscosity of experimental fluids that had been priorly determined on identical samples (8 ml of experimental fluid samples using a rotational viscometer (Haake RV-12 with a sensor (MV, Germany. Results Under the conditions of variable viscosity rates of seven experimental fluids (from 0.02 to 1309.04 mPa•s, we registered the time dependence of dynamic retention force of the experimental plate related to fluid viscosity during the action of the continual dislocating force of the separating directions. In addition, the maximal height of the dislocation of the experimental plate was registered. The dynamic retention force, manifested by the separating direction of the experimental plate dislocation, was increased concurrently with increased viscosity. Conclusion. The increase of dynamic retention force depends directly on medium viscosity. Close border values of fluid viscosity above the investigated ones, the impossibility of experimental layer thinning and the

  15. Evaluation of motion platform embedded with force plate-instrumented treadmill

    National Research Council Canada - National Science Library

    Emily H Sinitski; Edward D Lemaire; Natalie Baddour

    2015-01-01

    ... with a dual-belt treadmill and two force plates. The goal of this article was to investigate the performance characteristics associated with a treadmill-motion platform configuration and how system operation can affect the data collected...

  16. A new method to assess temporal features of gait initiation with a single force plate.

    Science.gov (United States)

    Moineau, Bastien; Boisgontier, Matthieu P; Barbieri, Guillaume; Nougier, Vincent

    2014-01-01

    The aim of this study was to investigate whether time of toe-off and heel-contact during gait initiation could be assessed with a single force plate. Twenty subjects performed ten self-paced gait initiations and seven other subjects performed ten gait initiations in four new conditions (slow, fast, obstacle and splint). Several force-plate parameters were measured with a single force plate, and actual toe-off and heel-contact were assessed with a motion analysis system. Results showed strong temporal correlations and closeness (r=.86-.99, mean error=3-86 ms) between two force-plate parameters and the kinematics events (toe-off and heel-contact). These new parameters may be of interest to easily measure duration of anticipatory postural adjustments and swing phase during clinical assessments.

  17. Two rods confined by positive plates: effective forces and charge distribution profiles

    Energy Technology Data Exchange (ETDEWEB)

    Odriozola, G; Jimenez-Angeles, F; Lozada-Cassou, M [Programa de IngenierIa Molecular, Instituto Mexicano del Petroleo, Lazaro Cardenas 152, 07730 Mexico, DF (Mexico)

    2006-09-13

    The effect of confinement on the interaction force between two negatively charged rods is studied through Monte Carlo simulations. Confinement is produced by two parallel, charged or uncharged plates. The system is immersed in a 0.1 M 1-1 restricted primitive model electrolyte. The effect on the rod-rod effective force by the plate charge distribution is analysed. A strong modification of the rod-rod effective force due to confinement is found, as compared to the bulk case. In particular, rod-rod attraction was found for plates having a charge equal to that of fully charged bilipid bilayers. In spite of the simplicity of the model, these results agree with some DNA-phospholipid experimental observations. On the other hand, for a model having the plate charges fixed on a grid, very long range, oscillatory rod-rod effective forces were obtained.

  18. Seismotectonics of the Lwandle-Nubia plate boundary between South Africa and the Southwest Indian Ridge

    Science.gov (United States)

    Hartnady, Chris; Okal, Emile; Calais, Eric; Stamps, Sarah; Saria, Elifuraha

    2013-04-01

    The Lwandle (LW) plate shares a boundary with the Nubia (NU) plate, extending from a diffuse triple junction with the Rovuma plate in Southern Mozambique to a triple junction with the Antarctic plate along a segment of the Southwest Indian Ridge (SWIR). The LW-NU boundary terminates in the ~750 km-long, complex transform of the Andrew Bain Fracture Zone (ABFZ), but its exact locus is still unclear. Recent works locate it along the eastern boundary of the submarine Mozambique Ridge, parallel to the pre-existing, oceanic transform-fault fabric. However, an early concept of the LW block ('ambiguous region' of Hartnady, 1990, Fig. 2) indicates a more westerly trajectory in the north that includes parts of South Africa, with a southerly extension across old oceanic crust of the submarine Natal Valley and Transkei Basin. This proposed boundary is marked by several, aligned epicentres of moderate to strong earthquakes (1941, 1942, 1956, 1969, 1972, 1975, 1981 and 1989). Our re-examination of seismographic records from the 1975 'intraplate' earthquake (-37.62°N, 30.98°E, mb5.0), in the oceanic crust of the distal Transkei Basin, shows a thrust-faulting focal mechanism along a nodal plane striking N272°E. The largest (ML4.2) of a series of three small earthquakes in the Natal Valley in 2009, close to a zone of recent seafloor deformation mapped in 1992, has similar first-motion patterns at Southern African seismograph stations. When the 1975 slip-vector result (N173°E) is combined with a normal-faulting slip vector (N078°E) from a 1986 onland earthquake (-30.53°N, 28.84°E, mb5.0) near the Lesotho-KZN border, and both are incorporated into the wider data-set previously used to solve for East African Rift kinematics, they produce a LW-NU rotation pole that is located south of Africa, near the Agulhas Plateau, and approximately 950 km from the Natal Valley deformation zone. The modeled low rate of right-lateral, LW-NU slip (~0.50-0.75 mm/yr) across this LW-NU boundary

  19. Buckling and Vibration of Non-Homogeneous Rectangular Plates Subjected to Linearly Varying In-Plane Force

    Directory of Open Access Journals (Sweden)

    Roshan Lal

    2013-01-01

    Full Text Available The present work analyses the buckling and vibration behaviour of non-homogeneous rectangular plates of uniform thickness on the basis of classical plate theory when the two opposite edges are simply supported and are subjected to linearly varying in-plane force. For non-homogeneity of the plate material it is assumed that young's modulus and density of the plate material vary exponentially along axial direction. The governing partial differential equation of motion of such plates has been reduced to an ordinary differential equation using the sine function for mode shapes between the simply supported edges. This resulting equation has been solved numerically employing differential quadrature method for three different combinations of clamped, simply supported and free boundary conditions at the other two edges. The effect of various parameters has been studied on the natural frequencies for the first three modes of vibration. Critical buckling loads have been computed. Three dimensional mode shapes have been presented. Comparison has been made with the known results.

  20. Crustal deformation evidences for viscous coupling and fragmented lithosphere at the Nubia-Iberia plate boundary (Western Mediterranean)

    Science.gov (United States)

    Palano, Mimmo; González, Pablo J.; Fernández, José

    2016-04-01

    A spatially dense crustal velocity field, based on up to 15 years of GNSS observations at more than 380 sites and extensively covering the Iberian Peninsula and Northern Africa, allow us to provide new insights into two main tectonic processes currently occurring in this area. We detected a slow large-scale clockwise rotation of the Iberian Peninsula with respect to a local pole located closely to the northwestern sector of the Pyrenean mountain range (Palano et al., 2015). Although this crustal deformation pattern could suggest a rigid rotating lithosphere block, this model would predict significant shortening along the Western (off-shore Lisbon) and North Iberian margin which cannot totally ruled out but currently is not clearly observed. Conversely, we favour the interpretation that this pattern reflects the quasi-continuous straining of the ductile lithosphere in some sectors of South and Western Iberia in response to viscous coupling of the NW Nubia and Iberian plate boundary in the Gulf of Cádiz. Furthermore, the western Mediterranean basin appears fragmented into independent crustal tectonic blocks, which delimited by inherited lithospheric shear structures and trapped within the Nubia-Eurasia collision, are currently accommodating most of the plate convergence rate. Among these blocks, an (oceanic-like western) Algerian one is currently transferring a significant fraction of the Nubia-Eurasia convergence rate into the Eastern Betics (SE Iberia) and likely causing the eastward motion of the Baleares Promontory. Most of the observed crustal ground deformation can be attributed to processes driven by spatially variable lithospheric plate forces imposed along the Nubia-Eurasia convergence boundary. Nevertheless, the observed deformation field infers a very low convergence rates as observed also at the eastern side of the western Mediterranean, along the Calabro Peloritan Arc, by space geodesy (e.g. Palano, 2015). References Palano M. (2015). On the present

  1. Modeling the Philippine Mobile Belt: Tectonic blocks in a deforming plate boundary zone

    Science.gov (United States)

    Galgana, G. A.; Hamburger, M. W.; McCaffrey, R.; Bacolcol, T. C.; Aurelio, M. A.

    2007-12-01

    The Philippine Mobile Belt, a seismically active, rapidly deforming plate boundary zone situated along the convergent Philippine Sea/Eurasian plate boundary, is examined using geodetic and seismological data. Oblique convergence between the Philippine Sea Plate and the Eurasian plate is accommodated by nearly orthogonal subduction along the Philippine Trench and the Manila Trench, as well as by strike-slip faulting along the Philippine Fault system. We develop a model of active plate boundary deformation in this region, using elastic block models constrained by known fault geometries, published GPS observations and focal mechanism solutions. We then present an estimate of block rotations, fault coupling, and intra-block deformation, based on the best-fit model that minimizes the misfit between observed and predicted geodetic vectors and earthquake slip vectors. Slip rates along the Philippine fault vary from ~22 - 36 mm/yr in the Central Visayas and about 10 to 40 mm/yr in Luzon, trending almost parallel to the fault trace. In northern Luzon, Philippine Fault splays accommodate transpressional strain. The Central Visayas block experiences convergence with the Sundaland block along the Negros Trench and the Mindoro-Palawan collision zone. On the eastern side of Central Visayas, sinistral strike-slip faulting occurs along the NNW-SSE-trending Philippine Fault. Mindanao Island in southern Philippines is dominated by east-verging subduction along the Cotabato Trench, and strain partitioning (strike- slip faulting with west-verging subduction) in eastern Mindanao along the southern Philippine Fault and Philippine Trench, respectively. Oblique active sinistral strike slip faults in Central and Eastern Mindanao that were hypothesized to be responsible for basin formation are obvious boundaries for tectonic blocks. Located south of Mindanao Island we define an adjoining oceanic block defined by the N-S trending complex dual subduction zone of Sangihe and Halmahera

  2. Distributed Plate Boundary Deformation Across the San Andreas Fault System, Central California

    Science.gov (United States)

    Dyson, M.; Titus, S. J.; Demets, C.; Tikoff, B.

    2007-12-01

    Plate boundaries are now recognized as broad zones of complex deformation as opposed to narrow zones with discrete offsets. When assessing how plate boundary deformation is accommodated, both spatially and temporally, it is therefore crucial to understand the relative contribution of the discrete and distributed components of deformation. The creeping segment of the San Andreas fault is an ideal location to study the distribution of plate boundary deformation for several reasons. First, the geometry of the fault system in central California is relatively simple. Plate motion is dominated by slip along the relatively linear strike-slip San Andreas fault, but also includes lesser slip along the adjacent and parallel Hosgri-San Gregorio and Rinconada faults, as well as within the borderlands between the three fault strands. Second, the aseismic character of the San Andreas fault in this region allows for the application of modern geodetic techniques to assess creep rates along the fault and across the region. Third, geologic structures within the borderlands are relatively well-preserved allowing comparison between modern and ancient rates and styles of deformation. Continuous GPS stations, alignment arrays surveys, and other geodetic methods demonstrate that approximately 5 mm/yr of distributed slip is accumulated (on top of the fault slip rate) across a 70-100 km wide region centered on the San Andreas fault. New campaign GPS data also suggest 2-5 mm/yr of deformation in the borderlands. These rates depend on the magnitude of the coseismic and postseismic corrections that must be made to our GPS time series to compensate for the 2003 San Simeon and 2004 Parkfield earthquakes, which rupture faults outside, but near the edges of our GPS network. The off-fault deformation pattern can be compared to the style of permanent deformation recorded in the geologic record. Fold and thrust belts in the borderlands are better developed in the Tertiary sedimentary rocks west of

  3. 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

  4. The boundary between the Indian and Asian tectonic plates below Tibet.

    Science.gov (United States)

    Zhao, Junmeng; Yuan, Xiaohui; Liu, Hongbing; Kumar, Prakash; Pei, Shunping; Kind, Rainer; Zhang, Zhongjie; Teng, Jiwen; Ding, Lin; Gao, Xing; Xu, Qiang; Wang, Wei

    2010-06-22

    The fate of the colliding Indian and Asian tectonic plates below the Tibetan high plateau may be visualized by, in addition to seismic tomography, mapping the deep seismic discontinuities, like the crust-mantle boundary (Moho), the lithosphere-asthenosphere boundary (LAB), or the discontinuities at 410 and 660 km depth. We herein present observations of seismic discontinuities with the P and S receiver function techniques beneath central and western Tibet along two new profiles and discuss the results in connection with results from earlier profiles, which did observe the LAB. The LAB of the Indian and Asian plates is well-imaged by several profiles and suggests a changing mode of India-Asia collision in the east-west direction. From eastern Himalayan syntaxis to the western edge of the Tarim Basin, the Indian lithosphere is underthrusting Tibet at an increasingly shallower angle and reaching progressively further to the north. A particular lithospheric region was formed in northern and eastern Tibet as a crush zone between the two colliding plates, the existence of which is marked by high temperature, low mantle seismic wavespeed (correlating with late arriving signals from the 410 discontinuity), poor Sn propagation, east and southeast oriented global positioning system displacements, and strikingly larger seismic (SKS) anisotropy.

  5. New GPS constraints on active deformation along the Africa-Iberia plate boundary

    Science.gov (United States)

    Koulali, A.; Ouazar, D.; Tahayt, A.; King, R. W.; Vernant, P.; Reilinger, R. E.; McClusky, S.; Mourabit, T.; Davila, J. M.; Amraoui, N.

    2011-08-01

    We use velocities from 65 continuous stations and 31 survey-mode GPS sites as well as kinematic modeling to investigate present day deformation along the Africa-Iberia plate boundary zone in the western Mediterranean region. The GPS velocity field shows southwestward motion of the central part of the Rif Mountains in northern Morocco with respect to Africa varying between 3.5 and 4.0 mm/yr, consistent with prior published results. Stations in the southwestern part of the Betic Mountains of southern Spain move west-southwest with respect to Eurasia (˜ 2-3 mm/yr). The western component of Betics motion is consistent with partial transfer of Nubia-Eurasia plate motion into the southern Betics. The southward component of Betics motion with respect to Iberia is kinematically consistent with south to southwest motion of the Rif Mountains with respect to Africa. We use block modeling, constrained by mapped surface faults and seismicity to estimate the geometry and rates of strain accumulation on plate boundary structures. Our preferred plate boundary geometry includes one block between Iberia and Africa including the SW Betics, Alboran Sea, and central Rif. This geometry provides a good fit to the observed motions, suggesting a wide transpressive boundary in the westernmost Mediterranean, with deformation mainly accommodated by the Gloria-Azores fault system to the West and the Rif-Tell lineament to the East. Block boundaries encompass aspects of earlier interpretations suggesting three main deformation styles: (i) extension along the NE-SW trending Trans-Alboran shear zone, (ii) dextral strike-slip in the Betics corresponding to a well defined E-W seismic lineament, and (iii) right lateral strike-slip motion extending West to the Azores and right-lateral motion with compression extending East along the Algerian Tell. We interpret differential motion in the Rif-Alboran-Betic system to be driven both by surface processes related the Africa-Eurasia oblique convergence and

  6. Smoothed particle hydrodynamics continuous boundary force method for Navier-Stokes equations subject to a Robin boundary condition

    Science.gov (United States)

    Pan, Wenxiao; Bao, Jie; Tartakovsky, Alexandre M.

    2014-02-01

    A Robin boundary condition for the Navier-Stokes equations is used to model slip conditions at the fluid-solid boundaries. A novel continuous boundary force (CBF) method is proposed for solving the Navier-Stokes equations subject to the Robin boundary condition. In the CBF method, the Robin boundary condition is replaced by the homogeneous Neumann boundary condition and a volumetric force term added to the momentum conservation equation. Smoothed particle hydrodynamics (SPH) method is used to solve the resulting Navier-Stokes equations. We present solutions for two- and three-dimensional flows subject to various forms of the Robin boundary condition in domains bounded by flat and curved boundaries. The numerical accuracy and convergence are examined through comparison of the SPH-CBF results with the solutions of finite difference or finite-element method. Considering the no-slip boundary condition as a special case of the slip boundary condition, we demonstrate that the SPH-CBF method accurately describes both the no-slip and slip conditions.

  7. EXPERIMENTAL STUDY ON TOTAL UPLIFT FORCES OF WAVES ON HORIZONTAL PLATES

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yi-ren; CHEN Guo-ping; WANG Deng-ting

    2004-01-01

    The total uplift forces of waves acting on hori zontal plates are the important basis for the design of maritime hollow-trussed structures. In this paper, an experimental study on the total uplift forces of waves on horizontal plates was conducted by a series of model tests. The results show that the maximum total uplift forces do not necessarily occur with the maximum impact pressure intensity synchronously.On the basis of the test results, formation mechanism of the total uplift forces of waves as well as its influencing factors were analyzed in detail, and an equation for calculation of the maximum total uplift forces of waves on plates was put forward. Lots of test data shows the present equation is in good agreement with the test results.

  8. Active faulting south of the Himalayan Front: Establishing a new plate boundary

    Science.gov (United States)

    Yeats, Robert S.; Thakur, V. C.

    2008-06-01

    New tectonic uplifts south of the Salt Range Thrust and Himalayan Front Thrust (HFT) represent an outward step of the plate boundary from the principal tectonic displacement zone into the Indo-Gangetic Plain. In Pakistan, the Lilla Anticline deforms fine-grained overbank deposits of the Jhelum River floodplain 15 km south of the Salt Range. The anticline is overpressured in Eocambrian non-marine strata. In northwest India south of Dehra Dun, the Piedmont Fault (PF) lies 15 km south of the HFT. Coalescing fans derived from the Himalaya form a piedmont (Old Piedmont Zone) 15-20 km wide east of the Yamuna River. This zone is uplifted as much as 15-20 m near the PF, and bedding is tilted 5-7° northeast. Holocene thermoluminescence-optically-stimulated luminescence dates for sediments in the Old Piedmont Zone suggest that the uplift rate might be as high as several mm/a. The Old Piedmont Zone is traced northwest 200 km and southeast another 200 km to the Nepal border. These structures, analogous to protothrusts in subduction zones, indicate that the Himalayan plate boundary is not a single structure but a series of structures across strike, including reactivated parts of the Main Boundary Thrust north of the range front, the HFT sensu stricto, and stepout structures on the Indo-Gangetic Plain. Displacement rates on all these structures must be added to determine the local India-Himalaya convergence rate.

  9. Forced Response of Polar Orthotropic Tapered Circular Plates Resting on Elastic Foundation

    Directory of Open Access Journals (Sweden)

    A. H. Ansari

    2016-01-01

    Full Text Available Forced axisymmetric response of polar orthotropic circular plates of linearly varying thickness resting on Winkler type of elastic foundation has been studied on the basis of classical plate theory. An approximate solution of problem has been obtained by Rayleigh Ritz method, which employs functions based upon the static deflection of polar orthotropic circular plates. The effect of transverse loadings has been studied for orthotropic circular plate resting on elastic foundation. The transverse deflections and bending moments are presented for various values of taper parameter, rigidity ratio, foundation parameter, and flexibility parameter under different types of loadings. A comparison of results with those available in literature shows an excellent agreement.

  10. Flat plate heat transfer for laminar transition and turbulent boundary layers using a shock tube

    Science.gov (United States)

    Brostmeyer, J. D.; Nagamatsu, H. T.

    1984-01-01

    Heat transfer results are presented for laminar, transition, and turbulent boundary layers for a Mach number of 0.12 with gas temperatures of 425 K and 1000 K over a flat plate at room temperature. The measurements were made in air for a Reynolds number range of 600 to 6 million. The heat transfer measurements were conducted in a 70-ft long, 4 in. diameter shock tube. Reflecting wedges were used to reflect the incident shock wave to produce a flow Mach number of 0.12 behind the reflected shock wave. Thin film platinum heat gages were mounted on the plate surface to measure the local heat flux. The laminar results for gas temperatures of 425 K to 1000 K agree well with theory. The turbulent results are also close to incompressible theory, with the 1000 K flow case being slightly higher. The transition results lie between the laminar and turbulent predictions.

  11. 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.

  12. Active faulting and transpression tectonics along the plate boundary in North Africa

    Directory of Open Access Journals (Sweden)

    Mustapha Meghraoui

    2013-01-01

    Full Text Available We present a synthesis of the active tectonics of the northern Atlas Mountains, and suggest a kinematic model of transpression and block rotation that illustrates the mechanics of this section of the Africa–Eurasia plate boundary. Neotectonic structures and significant shallow seismicity (with Mw >5.0 indicate that coeval E-W-trending, right-lateral faulting and NE-SW, thrust-related folding result from oblique convergence at the plate boundary, which forms a transpressional system. The strain distribution obtained from fault–fold structures and P axes of focal mechanism solutions, and the geodetic (NUVEL-1 and GPS convergence show that the shortening and convergence directions are not coaxial. The transpressional strain is partitioned along the strike and the quantitative description of the displacement field yields a compression-to-transcurrence ratio varying from 33% near Gibraltar, to 50% along the Tunisian Atlas. Shortening directions oriented NNE and NNW for the Pliocene and Quaternary, respectively, and the S shape of the Quaternary anticline axes, are in agreement with the 2.24˚/Myr to 3.9˚/Myr modeled clockwise rotation of the small tectonic blocks and with the paleomagnetic data. The convergence between Africa and Eurasia is absorbed along the Atlas Mountains at the upper crustal level, by means of thrusting above decollement systems, which are controlled by subdued transcurrent faults. The Tell Atlas of northwest Algeria, which has experienced numerous large earthquakes with respect to the other regions, is interpreted as a restraining bend that localizes the strain distribution along the plate boundary.

  13. The boundary point method for Reissner′s plates%Reissner型板边界点法

    Institute of Scientific and Technical Information of China (English)

    吴约; 王左辉

    2001-01-01

    In this paper, a series of particular solutions are formed by utilizing correspondent Reissher′s plate fundamental solutions. Thus all elements in the coefficient matrix of boundary element equations for plates to be solved will be determined by boundary point method. In the process of solving, interpolation and numerical integration are not needed and numerical treatment for singular integration is avoided, meanwhile, the calculation of physical characteristics of any point does not depend on boundary unknowns to be solved, therefore, the accuracy is excellent. The method presented may be applied to solving the problems of all kinds of plates and shells no matter if the problem is isotropic or anisotropic. But it should be noticed that the matrix of all particular solution field should conform with the fundamental solution of the specific problem.%文章采用Reissner型板基本解来构建一系列特解,再通过边界点法确定边界元方程系效矩阵的全部元素。解算中不涉及具体插值,不用数值积分,避免了奇性处理,而任意点物理量的计算不依赖于待解的边界未知量,算效高,精度好。该法还可用来分析其它各类板壳问题,无论是各向同性还是各向异性的,不同的只是应按各自的基本解来构造全特解场矩阵。

  14. Inherited segmentation of the Iberian-African margins and tectonic reconstruction of a diffuse plate boundary.

    Science.gov (United States)

    Fernàndez, Manel; Torne, Montserrat; Vergés, Jaume; Casciello, Emilio

    2016-04-01

    Diffuse plate-boundary regions are characterized by non-well defined contacts between tectonic plates thus making difficult their reconstruction through time. The Western Mediterranean is one of these regions, where the convergence between the African and Iberian plates since Late Cretaceous resulted in the Betic-Rif arcuate orogen, the Gulf of Cadiz imbricate wedge, and the Alboran back-arc basin. Whereas the Iberia-Africa plate boundary is well defined west to the Gorringe Bank and along the Gloria Fault, it becomes much more diffuse eastwards with seismicity spreading over both the south-Iberian and north-African margins. Gravity data, when filtered for short wavelengths, show conspicuous positive Bouguer anomalies associated with the Gorringe Bank, the Gulf of Cadiz High and the Ronda/Beni-Bousera peridotitic massifs reflecting an inherited Jurassic margin segmentation. The subsequent Alpine convergence between Africa and Iberia reactivated these domains, producing crustal-scale thrusting in the Atlantic segments and eventually subduction in the proto-Mediterranean segments. The Jurassic segmentation of the Iberia-Africa margins substantiates the double-polarity subduction model proposed for the region characterized by a change from SE-dipping polarity in the Gorringe, Gulf of Cadiz and Betic-Rif domains, to NW-dipping polarity in the proto-Algerian domain. Therefore, the Algerian and Tyrrhenian basins in the east and the Alboran basin in the west are the result of SSE-E and NW-W retreating slabs of oceanic and/or hyper-extended Tethyan domains, respectively.

  15. The Northern Caribbean Plate Boundary Offshore Hispaniola: Strike-slip and Compressive Tectonic Processes

    Science.gov (United States)

    Corbeau, J.; Rolandone, F.; Leroy, S. D.; Mercier De Lepinay, B. F.; Meyer, B.; Ellouz, N.

    2014-12-01

    The boundary between the Caribbean plate and the North American plate is transpressive due to the oblique collision between these two plates. The transpressive movement is partitioned and accommodated in the Hispaniola region along two left-lateral strike-slip structures surrounding a fold-and-thrust belt. New multibeam bathymetry data and multichannel seismic reflection profiles have been recently collected during the Haiti-SIS and Haiti-SIS 2 cruises, along part of the northern Caribbean plate boundary between Cuba, Jamaica and Hispaniola. From the north to the south, three types of deformations are observed. In the Windward Passage, the analysis of the data set reveals that the movement on the Oriente fault between Cuba and Hispaniola is purely left-lateral strike-slip according to the GPS measurements. In the Gonave basin, west of Hispaniola, the deformation is compressive. A series of folds is identified and moves toward the southwest. The Enriquillo-Plantain-Garden Fault (EPGF) is localized in the Jamaica Passage, between Jamaica and Hispaniola. The analysis of the data set reveals that the left-lateral EPGF recently intersects inherited basins from the eastern Cayman Trough margin. The study of the actual EPGF active trace shows that this fault moves with a pure strike-slip component, at least in its western part: the presence of a little push-up structure and a set of three en echelon folds is highlighting in the western part of the Jamaica Passage. The shortening rate in the inherited basins crossed by the EPGF increases from west to east (5.8% to 8.5%), indicating that a thrusting component is also accommodated around the EPGF.

  16. Geodetic and tectonic analyses along an active plate boundary: The central Gulf of California

    Science.gov (United States)

    Ortlieb, L.; Ruegg, J. C.; Angelier, J.; Colletta, B.; Kasser, M.; Lesage, P.

    1989-06-01

    The Gulf of California is traversed by the shear plate boundary between Pacific and North American plates and, because of several islands in its central part, offers the possibility of direct geodetic measurements of plate motion. A geodetic network of 150 km aperture, and comprising 11 stations, was measured in 1982 and 1986 by laser trilateration methods. The deformations deduced from the comparison of the two epochs indicate right-lateral shear strain covering the entire gulf rather than localized movements. In the eastern part of the network, between the axial islands and the Sonoran coast, significant right-lateral shear deformation occurs with a relative displacement of about 23 ± 12 cm over 4 years. In the northwestern region (Canal de Ballenas) a right-lateral displacement of about 17 ± 4 cm is observed, whereas in the southwestern part of the network (Canal Sal-si-Puedes), the deformation remains very weak. This suggests that south of the Canal de Ballenas the plate boundary is locked. A tectonic analysis of Neogene and Quaternary faults in Baja California, Sonora, and the central islands of the gulf, permitted the reconstruction of the stress pattern evolution of this area. These data also indicate the predominance of right-lateral motion on a NW-SE trending zone within a regional framework characterized by an approximately N-S compression and an E-W extension. The geodetic results are discussed in comparison with the neotectonic analysis and the seismic data available in the area. The data suggest a broad strain accumulation zone covering the totality of the central Gulf of California. A NW-SE relative velocity of about 8 ± 3 cm/yr is found between the two sides of the gulf during the 1982-1986 interval.

  17. 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

  18. Exact similarity solutions for forced convection flow over horizontal plate in saturated porous medium with temperature-dependent viscosity

    Science.gov (United States)

    Guedda, M.; Benlahsen, M.; Sriti, M.; Achemlal, D.

    2017-09-01

    In this paper, we revisit a mathematical model representing a two-dimensional forced convection boundary-layer flow over a horizontal impermeable plate with a variable heat flux and viscosity. It is assumed that the fluid viscosity varies as an inverse linear function of temperature, the free stream velocity varies as an inverse linear of x and the wall heat flux varies with x as x^{λ}; where λ > -1 and x measures the distance along the surface. Analytical local similarity solutions are presented which reveal that there are two competing effects: λ and θe; where θe is the variable viscosity parameter. It has been shown that for θe > 0 dual solutions exist and boundary separation occurs, while a unique local similarity solution exists for any θe < 0.

  19. Triangular Differential Quadrature for Bending Analysis of Reissner Plates with Curved Boundaries

    Institute of Scientific and Technical Information of China (English)

    华永霞; 钟宏志

    2003-01-01

    The recently proposed concept of the triangular differential quadrature method (TDQM) is applied to the bending analysis of Reissner plates with various curvilinear geometries subjected to various combinations of boundary conditions. A unit isosceles right triangle is used as the standard triangle for all the derivatives expressed using the triangular differential quadrature rule. Geometric transformations are introduced using basis functions to determine the weighting coefficients for the triangular differential quadrature to map an arbitrary curvilinear triangle into the standard triangle. The triangular differential quadrature method provides good accuracy and rapid convergence relative to other available exact and numerical results.

  20. 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.

  1. Coherent Structures in Transition of a Flat-Plate Boundary Layer at Ma=0.7

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ying; LI Xin-Liang; FU De-Xun; MA Yan-Wen

    2007-01-01

    @@ Direct numerical simulation (DNS) of a spatially evolving flat-plate boundary layer transition process at free stream Mach number 0.7 is performed. Tollmien-Schlichting (T-S) waves are added on the inlet boundary as the disturbances before transition. Typical coherent structures in the transition process are investigated based on the second invariant of velocity gradient tensor. The instantaneous shear stress and the mean velocity profile in the transition region are studied. In our view, the fact that the peak value of shear stress in the stress concentration area increases and exceeds a threshold value during the later stage of the transition process plays an important role in the laminar breakdown process.

  2. Fluid-mechanical Representation of Plate Boundaries - Trench-Ridge System -

    Science.gov (United States)

    Takaku, M.; Fukao, Y.

    2005-12-01

    Seismic tomography models have been used extensively to simulate mantle convection driven by density heterogeneity. Such simulation to date has been unsuccessful to reconcile itself with the most obvious convection-related phenomenon of plate motions. Here we present a theoretical framework for tomography-based convection modeling to include the plates as an integral part of the mantle convection. We model the lithosphere as a highly viscous, incompressible, Newtonian fluid layer and plate boundaries as faults across which tangential velocities are discontinuous. Fluid-mechanical expressions of such faults have their exact analogies in the seismic source representation theory and can be derived by referring to it. We test this idea against the simplest two-dimensional case with only trench and ridge as plate boundaries, and with only subducting slab as mass anomaly. We model ridge (trench) as the horizontal (vertical) tensile fault that comprises of a conjugate pair of 45-degree dip normal (reverse) faults extending over the entire thickness of the surface layer. The system comprises of three elementary convections, slab mass-driven convection, trench fault-driven convection and ridge fault-driven convection. Flow due to the slab excess mass imposes vertical tensile stress on trench, which is released by flow driven by trench faulting. This faulting converts efficiently the vertical tensile stress to the horizontal tensile stress, which can transmit to extreme distances through the surface viscous layer. This horizontal tensile stress is relieved by flow driven by ridge faulting. The three elementary convections are thus coupled through the stress minimum conditions at ridge and trench. The resultant coupled flow is very plate-like in the surface viscous layer. In this system the horizontal surface velocity depends little on the relative distance between the ridge and trench and depends mostly on the excess weight of the subducting slab. The horizontal speed can be

  3. Flowfield measurements in a separated and reattached flat plate turbulent boundary layer

    Science.gov (United States)

    Patrick, William P.

    1987-03-01

    The separation and reattachment of a large-scale, two-dimensional turbulent boundary layer at low subsonic speed on a flat plate has been studied experimentally. The separation bubble was 55 cm long and had a maximum bubble thickness, measured to the height of the mean dividing streamline, of 17 cm, which was twice the thickness of the inlet boundary layer. A combination of laser velocimetry, hot-wire anemometry, pneumatic probing techniques, and flow visualization were used as diagnostics. Principal findings were that an outer inviscid rotational flow was defined which essentially convected over the blockage associated with the inner, viscously dominated bubble recirculation region. A strong backflow region in which the flow moved upstream 100 percent of the time was measured near the test surface over the central 35 percent of the bubble. A laminar backflow boundary layer having pseudo-turbulent characteristics including a log-linear velocity profile was generated under the highly turbulent backflow. Velocity profile shapes in the reversed flow region matched a previously developed universal backflow profile at the upstream edge of the separation region but not in the steady backflow region downstream. A smoke flow visualization movie and hot-film measurements revealed low frequency nonperiodic flapping at reattachment. However, forward flow fraction data at reattachment and mean velocity profiles in the redeveloping boundary layer downstream of reattachment correlated with backward-facing step data when the axial dimension was scaled by the distance from the maximum bubble thickness to reattachment.

  4. RESEARCH ON THE COMPANION SOLUTION FOR A THIN PLATE IN THE MESHLESS LOCAL BOUNDARY INTEGRAL EQUATION METHOD

    Institute of Scientific and Technical Information of China (English)

    龙述尧; 熊渊博

    2004-01-01

    The meshless local boundary integral equation method is a currently developed numerical method, which combines the advantageous features of Galerkin finite element method(GFEM), boundary element method(BEM) and element free Galerkin method(EFGM), and is a truly meshless method possessing wide prospects in engineering applications.The companion solution and all the other formulas required in the meshless local boundary integral equation for a thin plate were presented, in order to make this method apply to solve the thin plate problem.

  5. The role of near-trench extension at convergent plate boundaries

    Science.gov (United States)

    Vannucchi, P.

    2009-04-01

    Knowledge of how convergent plate boundary coupling in the seismogenic zone controls the nucleation of subduction zone earthquakes is fundamental to assess seismic risks. Increased data at convergent margins has revealed the complexity of the earthquake cycle through the detection of strain-release processes like episodic tremors and slip events, low frequency earthquakes, afterslip, slip heterogeneity along the fault plane. The processes controlling the earthquake cycle and their interactions are still far from being understood; improved understanding will require better characterization of the fault zone. Here we compare in-situ observations from two major subduction zones drilled by ODP and IODP (Costa Rica Trench and Nankai Trough) with a well-preserved fossil convergent plate boundary zone in the Northern Apennines of Italy. At all three sites, deformation in the region above and at the updip limit of the seismogenic zone is dominated by extension and normal faulting (i.e. maximum principal stress is oriented sub-vertically). Episodes of reverse shearing are also present, but occur with less intensity, alternating with extension. Ocean Drilling Program Legs 170 and 205 offshore Costa Rica provide structural observations of the frontal part of the upper plate and décollement at about 2 km from the trench. Analysis of drilled cores reveals the presence of normal faults cutting the frontal part of the upper plate. Normal faults are also seen from seismic reflection to develop along all the forearc (about 60 km from the trench). The décollement damage zone is a few tens of meters in width; it develops mainly within frontal prism material. A clear cm-thick fault core is observed 1.6 km from the trench. Both the upper plate and the décollement damage zone show the co-existence of two distinct fracturing processes in which extension fracturing is frequent in the upper part of the damage zone farthest from the fault core, while both extension and shear fracturing

  6. Forced Convective Heat Transfer in a Porous Plate Channel

    Institute of Scientific and Technical Information of China (English)

    PeixueJiang; ZhanWang; 等

    1997-01-01

    Fored convective heat transfer in a plate channel filled with metallic spherical particales was investigated experimentally and numerically.The test section ,58mm×80mm×50mm in size,was heated by a 0.4mm thick plate electrical heater,The coolant water flow rate ranged from 0.015 to 0.833 kg/s.The local wall temperature distribution was measured along with the inlet and outlet fliud temperatures and pressures.The results illustrate the heat transfer augmentation and increased pressure drop caused by the porous medium.The heat transfer coefficient was increased 5-12 times by the porous media although the hydraulic resistance was increased even more.The Nusselt number and the heat transfer coefficient increased with decreasing particle diameter,while the pressure drop decreased as the particle diameter increased.It was found that,for the conditions studied(metallic packed bed),the effect of thermal dispersion did not need to be considered in the physical model,as opposed to a non-metallic packed bed,where thermal dispersion is important.

  7. Relaminarization of the boundary layer over a flat plate in shock tube experiments

    Science.gov (United States)

    Hinckel, J. N.; Nagamatsu, H. T.

    1986-01-01

    The relaminarization of the boundary layer over a flat plate in the shock tube was investigated by using the partially reflected shock wave technique. The flow Mach number was approximately 0.14, which corresponds to the inleft flow Mach number for the first row of vanes in a gas turbine. The thin film platinum heat gauges were used to measure the heat transfer rate and the Stanton number was calculated from the oscilloscope voltage traces. The Reynolds number was varied by changing the operation pressure of the shock tube and the values varied from 2.3 x 10 to the 4th to 5.3 x 10 to the 5th. For a Reynolds number range of 7 x 10 to the 4th to 3.5 x 10 to the 5th, the relaminarization of the boundary layer was observed. This phenomenon is due to the decay of the turbulence level in the flow as the reflected shock wave moves upstream from the flat plate. As the Reynolds number increased, the relaminarization was delayed and the delay was related to the turbulence generated by the reflected shock wave.

  8. 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.

  9. Dynamic Correction Algorithm of Rolling Force in Plate Rolling

    Institute of Scientific and Technical Information of China (English)

    QIU Hong-lei; WANG Jun; HU Xian-lei; WANG Zhao-dong; WANG Guo-dong

    2005-01-01

    Based on the Shougang plat mill project, an on-line dynamic correction algorithm was analyzed. This algorithm can adjust model coefficients better because the reasonable correction is based on the measured and calculated rolling force. The results of application on site show that this on-line dynamic correction algorithm is effective.

  10. Casimir densities for parallel plate in the Domain Wall background

    CERN Document Server

    Setare, M R

    2003-01-01

    The Casimir forces on two parallel plates in conformally flat domain wall background due to conformally coupled massless scalar field satisfying mixed boundary conditions on the plates is investigated. In the general case of mixed boundary conditions formulae are derived for the vacuum expectation values of the energy-momentum tensor and vacuum forces acting on boundaries.

  11. Crustal structure of the Eurasia-Africa plate boundary across the Gloria Fault, North Atlantic Ocean

    Science.gov (United States)

    Batista, Luis; Hübscher, Christian; Terrinha, Pedro; Matias, Luis; Afilhado, Alexandra; Lüdmann, Thomas

    2017-05-01

    The oceanic crustal and uppermost lithospheric mantle structure across the Gloria Fault (GF) transcurrent plate boundary between Africa and Eurasia in the Northeast Atlantic is investigated based on seismic reflection, seismic refraction and wide-angle reflection data. This experiment used 18 ocean bottom stations along an N-S 150 km long traverse together with acquisition of a multichannel seismic reflection profile. Modeling of P and S seismic waves and gravimetric anomalies allowed estimation of P- and S-wave velocities, density, Poisson's ratio and discussion of a compositional model. A five-layer model is proposed in which layers 1-3 correspond to normal sediments through typical oceanic crust layers 2 and 3. Layer 5 yielded mantle velocities above 7.9 km s-1. Layer 4 with 4 km of thickness has Vp velocities between 7.1 and 7.4 km s-1 and is clearly separated from typical oceanic crust and mantle layers. Comparison with natural analogues and published lab measurements suggest that layer 4 can be a mix of lithologies that comply with the estimated P and S velocities and computed Poisson's ratio and densities, such as, olivine cumulates, peridotite, gabbro and hydrated mantle. We favour the tectonic process that produces secondary porosity from which results serpentinization due to sea water circulation in fractures. Structural and seismic stratigraphic interpretation of the reflection profile shows that Neogene to recent tectonic deformation on this segment of the plate boundary concentrated on the southern side of the GF, that is, the Africa plate.

  12. Coefficient of Variation Estimates for the Plate Boundary Fault System of California

    Science.gov (United States)

    Biasi, G. P.; Scharer, K. M.

    2015-12-01

    The number of high-quality paleoseismic records on major strike-slip faults of California has increased in recent years to the point that patterns in earthquake recurrence are emerging. The degree of predictability in time intervals between ground-rupturing earthquakes can be measured by the CoV (coefficient of variation). The CoV approximately normalizes for mean recurrence, and is thus useful to isolate the temporal variability of earthquake records. CoV estimates are themselves uncertain because input dates are actually probability distributions and because paleoseismic records are short and not necessarily representative samples from the underlying recurrence distribution. Radiocarbon dating uncertainty can be incorporated by sampling from event PDFs and compiling sample CoV estimates. Uncertainty due to the brevity of the site event record is larger, and neglect of it can lead to improbable estimates. Long records are now available on the San Andreas and San Jacinto faults in Southern California, and the San Andreas and Hayward faults in northern California. These faults accommodate most of the Pacific-North American relative plate motion in their respective regions. CoV estimates from sites with 8 or more events cluster around 0.63, but are as low as 0.4 for the southern Hayward fault. Sites with fewer events give similar estimates, though with lower resolution. The one prominent outlier, Burro Flats, with a CoV near 1.0, is in a region of severe fault complexity and rapid fault-normal compression. Quasi-periodic recurrence is emerging as a general property for these plate boundary faults. Some individual site records allow that, at low probabilities, recurrence could be random in time. When the ensemble is considered together, however, it is improbable that we would see the observed degree of agreement among boundary fault paleoseismic records; the more likely explanation is that quasi-periodic recurrence is a real property of the boundary fault system.

  13. Experimental Study and System Identification of Hydrodynamic Force Acting on Heave Damping Plate

    Institute of Scientific and Technical Information of China (English)

    JI Heng-teng; FAN Ju; HUANG Xiang-lu

    2008-01-01

    Although Morison equation is often applied for simulating hydrodynamic force of marine structure, it may give poor results when non-linear behavior is severe or random wave is encountered. This leads to some modifications of Morison equation or other methods for predicting hydrodynamic force. One of them is the system identification technique. In this paper, NARMAX model theory is firstly used to identify the hydrodynamic system of heave damping plates, which are commonly installed on spar platform. Both linear and non-linear models are obtained. The comparisons between the predicted results and measured data indicate that NARMAX model can predict hydrodynamic force of a heave damping plate very well. The measured data for identification originate from forced oscillation tests, which are random records with given spectrum. The forced oscillation forms in experiment also contain simple harmonic, multi-frequency ones.

  14. Normative values for a video-force plate assessment of postural control in athletic children.

    Science.gov (United States)

    Howell, David R; Meehan, William P

    2016-07-01

    The objective of this study was to provide normative data for young athletes during the three stances of the modified Balance Error Scoring System (mBESS) using an objective video-force plate system. Postural control was measured in 398 athletes between 8 and 18 years of age during the three stances of the mBESS using a video-force plate rating system. Girls exhibited better postural control than boys during each stance of the mBESS. Age was not significantly associated with postural control. We provide normative data for a video-force plate assessment of postural stability in pediatric athletes during the three stances of the mBESS.

  15. Thermochronology and tectonics of the Leeward Antilles: Evolution of the southern Caribbean Plate boundary zone

    Science.gov (United States)

    van der Lelij, Roelant; Spikings, Richard A.; Kerr, Andrew C.; Kounov, Alexandre; Cosca, Michael; Chew, David; Villagomez, Diego

    2010-01-01

    Tectonic reconstructions of the Caribbean Plate are severely hampered by a paucity of geochronologic and exhumation constraints from anastomosed basement blocks along its southern margin. New U/Pb, 40Ar/39Ar, apatite fission track, and apatite (U-Th)/He data constrain quantitative thermal and exhumation histories, which have been used to propose a model for the tectonic evolution of the emergent parts of the Bonaire Block and the southern Caribbean Plate boundary zone. An east facing arc system intruded through an oceanic plateau during ~90 to ~87 Ma and crops out on Aruba. Subsequent structural displacements resulted in >80°C of cooling on Aruba during 70–60 Ma. In contrast, exhumation of the island arc sequence exposed on Bonaire occurred at 85–80 Ma and 55–45 Ma. Santonian exhumation on Bonaire occurred immediately subsequent to burial metamorphism and may have been driven by the collision of a west facing island arc with the Caribbean Plate. Island arc rocks intruded oceanic plateau rocks on Gran Roque at ~65 Ma and exhumed rapidly at 55–45 Ma. We attribute Maastrichtian-Danian exhumation on Aruba and early Eocene exhumation on Bonaire and Gran Roque to sequential diachronous accretion of their basement units to the South American Plate. Widespread unconformities indicate late Eocene subaerial exposure. Late Oligocene–early Miocene dextral transtension within the Bonaire Block drove subsidence and burial of crystalline basement rocks of the Leeward Antilles to ≤1 km. Late Miocene–recent transpression caused inversion and ≤1 km of exhumation, possibly as a result of the northward escape of the Maracaibo Block.

  16. Limit State Analysis of Reinforced Concrete Plates subjected to in-plane forces

    DEFF Research Database (Denmark)

    Poulsen, Peter Noe; Damkilde, Lars

    2000-01-01

    A finite element formulation of rigid-plastic plates subjected to in-plane forces is developed using stress-based elements and linear programming. Three elements are established, namely a triangular plate element, a bar element and a beam element. The problem is formulated as a lower bound solution......, and the dual variables are interpreted as displacements. Both load and material optimization are formulated. The method is applied to concrete plate structures modelling both the distributed and the concentrated reinforcement. An efficient computational scheme is used, thereby reducing the size of the problem...

  17. Unsteady Hydromagnetic Flow past a Moving Vertical Plate with Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    Gauri Shanker Seth

    2016-01-01

    Full Text Available Investigation of unsteady MHD natural convection flow through a fluid-saturated porous medium of a viscous, incompressible, electrically-conducting and optically-thin radiating fluid past an impulsively moving semi-infinite vertical plate with convective surface boundary condition is carried out. With the aim to replicate practical situations, the heat transfer and thermal expansion coefficients are chosen to be constant and a new set of non-dimensional quantities and parameters are introduced to represent the governing equations along with initial and boundary conditions in dimensionless form. Solution of the initial boundary-value problem (IBVP is obtained by an efficient implicit finite-difference scheme of the Crank-Nicolson type which is one of the most popular schemes to solve IBVPs. The numerical values of fluid velocity and fluid temperature are depicted graphically whereas those of the shear stress at the wall, wall temperature and the wall heat transfer are presented in tabular form for various values of the pertinent flow parameters. A comparison with previously published papers is made for validation of the numerical code and the results are found to be in good agreement.

  18. 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...

  19. Non-linear resonances in the forced responses of plates. I - Symmetric responses of circular plates

    Science.gov (United States)

    Sridhar, S.; Mook, D. T.; Nayfeh, A. H.

    1975-01-01

    The dynamic analogue of the von Karman equations is used to study the symmetric response of a circular plate to a harmonic excitation when the frequency of the excitation is near one of the natural frequencies. It is shown that, in general, when there is no internal resonance (i.e., the natural frequencies are not commensurable), only the mode having a frequency near that of the excitation is strongly excited (i.e., is needed to represent the response in the first approximation). A clamped, circular plate is used as a numerical example to show that, when there is an internal resonance, more than one of the modes involved in this resonance can be strongly excited; moreover, when more than one mode is strongly excited, the lower modes can dominate the response, even when the frequency of the excitation is near that of the highest mode. This possibility was not revealed by any of the earlier studies which were based on the same governing equations.

  20. Highly asymmetric interaction forces induced by acoustic waves in coupled plate structures

    CERN Document Server

    Fan, Xiying; Zhang, Shenwei; Ke, Manzhu; Liu, Zhengyou

    2015-01-01

    Mutual forces can be induced between coupled structures when illuminated by external acoustic waves. In this Letter, we propose a concept of asymmetric interaction between two coupled plate-like structures, which is generated by oppositely incident plane waves. Besides the striking contrast in magnitude, the mutual force induced by one of the incidences can be tuned extremely strong due to the resonant excitation of the flexural plate modes. The highly asymmetric interaction with enhanced strength in single side should be potentially useful, such as in designing ultrasound instruments and sensors.

  1. EarthScope Plate Boundary Observatory Data in the College Classroom (Invited)

    Science.gov (United States)

    Eriksson, S. C.; Olds, S. E.

    2009-12-01

    The Plate Boundary Observatory (PBO) is the geodetic component of the EarthScope project, designed to study the 3-D strain field across the active boundary zone between the Pacific and North American tectonics plates in the western United States. All PBO data are freely available to scientific and educational communities and have been incorporated into a variety of activities for college and university classrooms. UNAVCO Education and Outreach program staff have worked closely with faculty users, scientific researchers, and facility staff to create materials that are scientifically and technically accurate as well as useful to the classroom user. Availability of processed GPS data is not new to the geoscience community. However, PBO data staff have worked with education staff to deliver data that are readily accessible to educators. The UNAVCO Data for Educators webpage, incorporating an embedded Google Map with PBO GPS locations and providing current GPS time series plots and downloadable data, extends and updates the datasets available to our community. Google Earth allows the visualization GPS data with other types of datasets, e.g. LiDAR, while maintaining the self-contained and easy-to-use interface of UNAVCO’s Jules Verne Voyager map tools, which have multiple sets of geological and geophysical data. Curricular materials provide scaffolds for using EarthScope data in a variety of forms for different learning goals. Simple visualization of earthquake epicenters and locations of volcanoes can be used with velocity vectors to make simple deductions of plate boundary behaviors. Readily available time series plots provide opportunities for additional science skills, and there are web and paper-based support materials for downloading data, manipulating tables, and using plotting programs for processed GPS data. Scientists have provided contextual materials to explore the importance of these data in interpreting the structure and dynamics of the Earth. These data

  2. The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand

    Science.gov (United States)

    Menzies, Catriona D.; Teagle, Damon A. H.; Niedermann, Samuel; Cox, Simon C.; Craw, Dave; Zimmer, Martin; Cooper, Matthew J.; Erzinger, Jörg

    2016-07-01

    Fluids play a key role in modifying the chemical and physical properties of fault zones, which may prime them for repeated rupture by the generation of high pore fluid pressures and precipitation of commonly weak, secondary minerals. Fluid flow paths, sources and fluxes, and the permeability evolution of fault zones throughout their seismic cycles remain poorly constrained, despite their importance to understanding fault zone behaviour. Here we use geochemical tracers of fluid-rock exchange to determine budgets for meteoric, metamorphic and mantle fluids on a major compressional tectonic plate boundary. The Alpine Fault marks the transpressional Pacific-Australian plate boundary through South Island, New Zealand and appears to fail in regular (329 ± 68 yrs) large earthquakes (Mw ∼ 8) with the most recent event in 1717 AD. Significant convergent motion has formed the Southern Alps and elevated geothermal gradients in the hangingwall, which drive crustal fluid flow. Along the Alpine Fault the Alpine Schist of the Pacific Plate is thrust over radiogenic metasedimentary rocks on the Australian plate. The absence of highly radiogenic (87Sr/86Sr > 0.7200) strontium isotope ratios of hangingwall hot springs and hydrothermal minerals formed at a range of depths in the Alpine Fault damage zone indicates that the fluid flow is restricted to the hangingwall by a cross-fault fluid flow barrier throughout the seismogenic crust. Helium isotope ratios measured in hot springs near to the Alpine Fault (0.15-0.81 RA) indicate the fault is a crustal-scale feature that acts as a conduit for fluids from the mantle. Rock-exchanged oxygen, but meteoric water-like hydrogen isotope signatures of hydrothermal veins indicate that partially rock-exchanged meteoric fluids dominate down to the top of the brittle to ductile transition zone at ∼6 km. Geochemical tracer transport modelling suggests only ∼0.02 to 0.05% of total rainfall west of the Main Divide penetrates to depth, yet this

  3. Laboratory-observed frictional slip instabilities in samples of the Tohoku plate boundary megathrust

    Science.gov (United States)

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

    2014-12-01

    The plate boundary megathrust at the Japan Trench is remarkable due to its capability for a wide range of fault slip styles. In addition to the extraordinarily large amount of coseismic slip (several 10's of meters) that reached the seafloor during the 2011 Tohoku-Oki earthquake, the the Japan Trench is also known host slow earthquakes. The location of these slow earthquakes coincide with the rupture area of the 2011 Tohoku earthquake; one was observed to occur in the month before the 2011 earthquake and was likely ongoing during the earthquake. This shows that the frictional behavior of the Japan Trench megathrust is complex and thus failure can occur in a variety of styles. Samples of the plate boundary fault zone in the Tohoku region were recovered ~7 km from the Japan Trench axis, within the region of largest coseismic slip during the Tohoku earthquakes, during Integrated Ocean Drilling Program Expedition 343, the Japan Trench Fast Drilling Project (JFAST). We used these samples in laboratory friction experiments in order to examine the slip behavior of the shallow Tohoku megathrust. In our tests, we sheared the samples at 10 μm/s to establish a steady shear geometry and friction level and subsequently decrease the slip velocity to 2.7 nm/s, equal to the convergence rate between the Pacific and North American plates (85 mm/yr) and thus simulating realistically slow fault slip rates. Regular stick-slip behavior was observed soon after the velocity decrease but ceases as friction evolves to a new residual level. Shearing then mostly proceeds as stable creep, however infrequent friction perturbations are observed which occur two to three times over several mm. Unlike normal stick-slip behavior, we observe stress increases before the stress drop so that the friction level before and after the event are similar. The stress drop is ~0.015 in friction (~100 kPa) and occurs over several hours; therefore we interpret these events to be laboratory-generated slow

  4. Detection of Reflected Waves from Plate Boundary Using ACROSS Source and Seismic Array

    Science.gov (United States)

    Soma, T.; Watanabe, T.; Ikuta, R.; Saiga, A.; Miyajima, R.; Yamaoka, K.; Tsuruga, K.; Kunitomo, T.; Hasada, Y.; Kasahara, J.; Satomura, M.; Kumazawa, M.; Fujii, N.

    2005-12-01

    ACROSS (Accurately Controlled and Routinely Operated Signal System) is effective in monitoring temporary changes of Earth's interior. A long-term operation experiment near Nojima fault [Ikuta et al.,2004] detected small temporary changes of travel time of P and S waves at tele-seismic events. Toward Tokai monitoring plan to detect the reflected phases from the top of Philippine Sea Plate and monitor its temporal changes, a mid-term continuous experiment was conducted using ACROSS source and a seismic array. The experiment was operated for the period from Dec. 2004 to Sep.2005 in the Tokai area, Pacific side of the central part of Japan. In this region, the expected Tokai earthquake is a serious concern. In addition, slow slip events and low-frequency tremors are observed in this area. A strong reflected phase from the plate boundary was found by the seismic observation using artificial sources [Iidaka et al.,2003]. The purpose of the experiment is to establish a method to detect and monitor the reflection from the plate boundary using ACROSS. The ACROSS source is located in Toki city and operated by Tono Geoscience Center. The ACROSS source continuously transmits precisely-controlled frequency-modulated signals whose frequency band ranges from 10 to 20 Hz with an interval of 50 seconds. We deployed a short-span seismic array at the distance of 55 km from the ACROSS source. The cross-shaped seismic array spanning 2 km consists of 12 seismometers equipped with an offline data logger, amplifier and solarpanel. We stacked the received signal for a month with an interval of 200 seconds in order to improve signal noise ratio. We extracted a series of line spectrum of ACROSS signal. Transfer function can be obtained by dividing spectrum by the source. Applying inverse Fourier transform, we can obtain the transfer function in time-domain. We identified direct P and S phases by comparing with the standard travel time table by JMA. We also found some coherent later phases

  5. Laminar forced convection with viscous dissipation in a Couette-Poiseuille flow between parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Orhan; Avci, Mete [Karadeniz Technical University, Trabzon (Turkey). Department of Mechanical Engineering

    2006-08-15

    In this study, analytical solutions are obtained to predict laminar heat-convection in a Couette-Poiseuille flow between two plane parallel plates with a simultaneous pressure gradient and an axial movement of the upper plate. A Newtonian fluid with constant properties is considered with an emphasis on the viscous-dissipation effect. Both hydrodynamically and thermally fully-developed flow cases are investigated. The axial heat-conduction in the fluid is neglected. Two different orientations of the thermal boundary-conditions are considered: the constant heat-flux at the upper plate with an adiabatic lower plate (Case A) and the constant heat-flux at the lower plate with an adiabatic upper plate (Case B). For different values of the relative velocity of the upper plate, the effect of the modified Brinkman number on the temperature distribution and the Nusselt number are discussed. Comparison of the present analytical results for a special case with those available in the literature indicates an excellent agreement. (author)

  6. Tectonic lineaments in the cenozoic volcanics of southern Guatemala: Evidence for a broad continental plate boundary zone

    Science.gov (United States)

    Baltuck, M.; Dixon, T. H.

    1984-01-01

    The northern Caribbean plate boundary has been undergoing left lateral strike slip motion since middle Tertiary time. The western part of the boundary occurs in a complex tectonic zone in the continental crust of Guatemala and southernmost Mexico, along the Chixoy-Polochic, Motogua and possibly Jocotan-Chamelecon faults. Prominent lineaments visible in radar imagery in the Neogene volcanic belt of southern Guatemala and western El Salvador were mapped and interpreted to suggest southwest extensions of this already broad plate boundary zone. Because these extensions can be traced beneath Quaternary volcanic cover, it is thought that this newly mapped fault zone is active and is accommodating some of the strain related to motion between the North American and Caribbean plates. Onshore exposures of the Motoqua-Polochic fault systems are characterized by abundant, tectonically emplaced ultramafic rocks. A similar mode of emplacement for these off shore ultramafics, is suggested.

  7. EarthScope's Plate Boundary Observatory as the Mother of Invention (Invited)

    Science.gov (United States)

    Blewitt, G.; Hammond, W. C.; Kreemer, C.

    2013-12-01

    The Plate Boundary Observatory (PBO) component of EarthScope includes a network of over 1,100 permanent, continuously operating GPS stations. After 5 years of site selection, permitting, and construction, the network was completed in 2008. Having such an unprecedented number of high quality stations in western North America has enabled us to image geology in action, as it happens, such as contemporary uplift of the Sierra Nevada, and block rotation in the Walker Lane. Yet, when PBO was in its planning stages, questions were raised as to whether GPS analysis could keep up with the flood of data, while producing results with the highest achievable accuracy. The general consensus was that the challenge would be met by a combination of innovative data processing methods together with the inevitable progress in computer speed and capacity. Various innovations made by the geodetic community over the last decade have enabled massive operational processing of GPS data with high accuracy. For example, now in 2013, the Nevada Geodetic Laboratory operationally produces position time series and quality assurance data from all ~7,000 GPS geodetic stations in the world that make data publicly available. Of these stations, 4,000 have daily time series updated the next day, and 2,000 have 5-minute time series updated within 1-2 hours of real time. The RMS precision of daily positions for well-sited stations are at the level of 1-2 mm horizontal, and 3-6 mm vertical in the International Terrestrial Reference Frame (ITRF). For 5-minute positions, the precision is at the level of 6-12 mm horizontal, and 15-30 mm vertical. Here we review some of the innovations that have made all of this possible, which were in part driven by challenges presented by EarthScope. First of all, at the data processing level, much creative effort went into making computer processing time scale linearly with the number of GPS stations. The Precise Point Positioning (PPP) technique invented in 1997 has been

  8. 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

  9. Plate tectonics and offshore boundary delimitation: Tunisia-Libya case at the International Court of Justice

    Science.gov (United States)

    Stanley, Daniel Jean

    1982-03-01

    The first major offshore boundary dispute where plate tectonics constituted a significant argument was recently brought before the International Court of Justice by Libya and Tunisia concerning the delimitation of their continental shelves. Libya placed emphasis on this concept to determine natural prolongation of its land territory under the sea. Tunisia contested use of the entire African continental landmass as a reference unit and views geography, geomorphology and bathymetry as relevant as geology. The Court pronounced that “It is the outcome, not the evolution in the long-distant past, which is of importance.” Moreover, it is the present-day configuration of coasts and seabed that are the main factors, not geology.

  10. Abrupt thermal transition reveals hydrothermal boundary and role of seamounts within the Cocos Plate

    Science.gov (United States)

    Fisher, A. T.; Stein, C. A.; Harris, R. N.; Wang, K.; Silver, E. A.; Pfender, M.; Hutnak, M.; Cherkaoui, A.; Bodzin, R.; Villinger, H.

    2003-06-01

    New thermal data from 18-24 Ma lithosphere on the Cocos Plate delineate contrasting subsurface thermal conditions in adjacent sections of crust. Heat flow through seafloor created at the East Pacific Rise is generally suppressed by ~70% relative to conductive lithospheric cooling models, whereas heat flow through adjacent, similarly-aged lithosphere generated at the Cocos-Nazca Spreading Center is consistent with these models. The transition between thermal regimes is remarkably abrupt, only 2-5 km wide, indicating a shallow hydrothermal origin. The transition is more closely associated with differences in the distribution of basement outcrops than with tectonic boundaries, demonstrating the importance of the former in extracting heat from the lithosphere on a regional basis.

  11. 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.

  12. Recovering physical property information from subduction plate boundaries using 3D full-waveform seismic inversion

    Science.gov (United States)

    Bell, R. E.; Morgan, J. V.; Warner, M.

    2013-12-01

    Our understanding of subduction margin seismogenesis has been revolutionised in the last couple of decades with the discovery that the size of the seismogenic zone may not be controlled simply by temperature and a broad spectrum of seismic behaviour exists from stick-slip to stable sliding. Laboratory and numerical experiments suggest that physical properties, particularly fluid pressure may play an important role in controlling the seismic behaviour of subduction margins. Although drilling can provide information on physical properties along subduction thrust faults at point locations at relatively shallow depths, correlations between physical properties and seismic velocity using rock physics relationships are required to resolve physical properties along the margin and down-dip. Therefore, high resolution seismic velocity models are key to recovering physical property information at subduction plate boundaries away from drill sites. 3D Full waveform inversion (FWI) is a technique pioneered by the oil industry to obtain high-resolution high-fidelity models of physical properties in the sub-surface. 3D FWI involves the inversion of low-frequency (>2 to noise and inverted the windowed transmitted arrivals only. We also ran a suite of resolution tests across the model. The results show that 3D FWI of conventionally collected 3D seismic data across the Muroto Basin would be capable of resolving variations in P-wave velocity along the décollement of the order of half the seismic wavelength at the plate boundary. This is a significant improvement on conventional travel-time tomography which resolves to the Fresnel width. In this presentation we will also postulate on the optimal 3D FWI experiment design for the next generation of 3D seismic surveys across subduction margins as a guide for those embarking on new data collection.

  13. A mixed problem of plate bending for doubly connected domains with partially unknown boundaries in the presence of cyclic symmetry

    Institute of Scientific and Technical Information of China (English)

    Odishelidze; N; Criado-Aldeanueva; F

    2010-01-01

    This paper addresses the problem of plate bending for a doubly connected body with outer and inner boundaries in the form of regular polygons with a common center and parallel sides.The neighborhoods of the vertices of the inner boundary are equal full-strength smooth arcs symmetric about the rays coming from the vertices to the center,but have unknown positions.Rigid bars are attached to the linear parts of the boundary.The plate bends by the moments applied to the middle point bars.The unknown arcs are free from external stresses.The same problem of plate bending is considered for a regular hexagon weakened by a full-strength hole.Using the methods of complex analysis,the analytical image of Kolosov-Muskhelishvili’s complex potentials (characterizing an elastic equilibrium of the body),the plate deflection and unknown parts of its boundary are determined under the condition that the tangential normal moment on that plate takes a constant value.Numerical analyses are also performed and the corresponding graphs are constructed.

  14. Geophysical surveys of the Queen Charlotte Fault plate boundary off SE Alaska: Preliminary results

    Science.gov (United States)

    Ten Brink, U. S.; Brothers, D. S.; Andrews, B. D.; Kluesner, J.; Haeussler, P. J.; Miller, N. C.; Watt, J. T.; Dartnell, P.; East, A. E.

    2016-12-01

    Recent multibeam sonar and high-resolution seismic surveys covering the northern 400-km-long segment of Queen Charlotte Fault off SE Alaska, indicate that the entire 50 mm/yr right-lateral Pacific-North America plate motion is currently accommodated by a single fault trace. The trace is remarkably straight rarely interrupted by step-overs, and is often Internal basin stratigraphy indicates possible southward migration of the step-over with time. Slight outward curving of the southern strand may suggest the presence of a deeper barrier there, which could have terminated the northward super-shear rupture of the 2013 M7.5 Craig Earthquake. Whether this possible barrier is related to the intersection of the Aja Fracture Zone with the plate boundary is unclear. No other surficial impediments to rupture were observed along the 315 km trace between this fault step-over and a 20° bend near Icy Point, where the fault extends onshore and becomes highly transpressional. An enigmatic oval depression, 1.5-2 km wide and 500 m deep, south of the step-over and a possible mud volcano north of the step-over, may attest to possible vigorous gas and fluid upwelling along the fault zone.

  15. Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

    NARCIS (Netherlands)

    Percin, M.; Van Oudheusden, B.W.

    2015-01-01

    Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition

  16. Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates

    NARCIS (Netherlands)

    Percin, M.; Van Oudheusden, B.W.

    2015-01-01

    Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition

  17. Natural convective boundary layer flow of a nano-fluid past a convectively heated vertical plate

    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, PN Engineering College, National University of Sciences and Technology, Karachi 75350 (Pakistan)

    2012-03-15

    Natural convective flow of a nano-fluid over a convectively heated vertical plate is investigated using a similarity analysis of the transport equations followed by their numerical computations. The transport model employed includes the effect of Brownian motion and thermophoresis. The analysis shows that velocity, temperature and solid volume fraction of the nano-fluid profiles in the respective boundary layers depend, besides the Prandtl and Lewis numbers, on four additional dimensionless parameters, namely a Brownian motion parameter Nb, a thermophoresis parameter Nt, a buoyancy-ratio parameter Nr and convective parameter Nc. In addition to the study of these parameters on the boundary layer flow characteristics (velocity, temperature, solid volume fraction of the nano-fluid, skin friction, and heat transfer), correlations for the Nusselt and Sherwood numbers have been developed based on a regression analysis of the data. These linear regression models provide a highly accurate (with a maximum standard error of 0.004) representation of the numerical data and can be conveniently used in engineering practice. (authors)

  18. 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.

  19. Towards understanding earthquake nucleation on a severely misoriented plate boundary fault, Alpine Fault, New Zealand

    Science.gov (United States)

    Boulton, C. J.; Faulkner, D. R.; Allen, M. J.; Coussens, J.; Menzies, C. D.; Mariani, E.

    2016-12-01

    New Zealand's Alpine Fault has accommodated relative motion between the Australian and Pacific plates for over 23 million years: first as strike-slip fault and then as an oblique transpressional fault. Despite being driven by principal stresses whose orientations have undoubtedly changed with time, the Alpine Fault continues to accommodate 70% of the relative plate boundary motion. Fault outcrop data and seismic reflection data indicate that the central Alpine Fault is consistently oriented 055/45°SE at depths up to 15 km (i.e., throughout the seismogenic zone); focal mechanisms indicate that the stress tensor is oriented σ1=σHmax=0/117°, σ2=σv, and σ3=0/207° (Boese et al. 2013, doi: 10.1016/j.epsl.2013.06.030). At depth, the central Alpine Fault lies at an angle of 51° to σ1. The Mohr-Coulomb failure criterion stipulates that, for incohesive rocks, reactivation of a fault requires sufficient driving stress to overcome frictional resistance to slip. Using a coefficient of friction (μ) of 0.6, as measured for representative Alpine Fault rocks under in situ conditions (Neimeijer et al. 2016, doi:10.1002/2015JB012593), and an estimated stress shape ratio (Φ=(σ2 - σ3)/(σ1 - σ3)=0.5), a 3-D reactivation analysis was performed (Leclère and Fabbri 2013, doi:10.1016/j.jsg.2012.11.004). Results show that the Alpine Fault is severely misoriented for failure, requiring pore fluid pressures greater than the least principal stress to initiate frictional sliding. However, microstructural evidence, including pseudotachylytes and fault gouge injection structures, suggests that earthquakes nucleate and propagate along this major plate boundary fault. By assuming an increase in differential stress of 15 MPa/km, our analysis shows that reactivation may occur with suprahydrostatic pore fluid pressures given a ≥10° counterclockwise rotation of σHmax. Using measured hydraulic data, we estimate the potential for pore fluid overpressure development within the Alpine

  20. Behavior of Boundary Layer in Supersonic Flow with Applied Lorentz Force

    Science.gov (United States)

    Udagawa, Keisuke; Saito, Shinya; Kawaguchi, Kenji; Tomioka, Sadatake; Yamasaki, Hiroyuki

    Experimental study on behavior of boundary layer in supersonic flow with applied Lorentz force was carried out. In the experiment, Mach 1.5 supersonic wind tunnel driven by a shock-tube was used. At the test section, the current from the external DC power supply and the magnetic field of 2.4 Tesla were applied to the boundary layer developing on the bottom wall. Argon seeded with cesium was used as an electrically conducting gas. Effect of the direction of the Lorentz force on static pressure distribution was investigated, and the remarkable increase of static pressure at the test section was observed for the decelerating Lorentz force. It is noted that the acceleration of the flow inside the boundary layer was demonstrated for the first time without accelerating the main flow when the accelerating Lorentz force was applied. At the same time, the acceleration efficiency defined by a ratio of work done by the Lorentz force to energy input into the flow was found 54-61%. These results have suggested the possibility of the boundary layer separation control by applying the accelerating Lorentz force. In the case of the decelerating Lorentz force, the significant reduction of Mach number was observed not only inside the boundary layer but also in the main flow. The reduction of Mach number could be ascribed to the growth of the boundary layer due to gas heating inside the boundary layer. When the direction of the current was changed, the difference of light emission from the discharge inside the boundary layer was observed, and this was due to the difference of the electromotive force induced in the supersonic flow.

  1. Lost in Iceland? Fracture Zone Complications Along the Mid-Atlantic Plate Boundary

    Science.gov (United States)

    Brandsdóttir, B.; Einarsson, P.; Detrick, R. S.; Mayer, L.; Calder, B.; Driscoll, N.; Richter, B.

    2003-12-01

    The mid-Atlantic plate boundary breaks up into a series of segments across Iceland. Two transform zones, the South Iceland Seismic Zone (SISZ) and the Tjörnes Fracture Zone (TFZ) separate the on land rift zones from the Reykjanes Ridge (RR), and the Kolbeinsey Ridge (KR), offshore N-Iceland. Both are markedly different from fracture zones elsewhere along the plate boundary. The 80 km E-W and 10--15 km N-S SISZ is made up of more than 20 N-S aligned, right-lateral, strike-slip faults whereas the TFZ consists of a broad zone of deformation, roughly 150 km E-W and 75 km N-S. The over-all left-lateral transform motion within the SISZ is accommodated by bookshelf faulting whereas the right-lateral transform motion within the TFZ is incorporated within two WNW-trending seismic zones, spaced ˜40 km apart, the Grímsey Seismic Zone (GSZ) and the Húsavík-Flatey fault (HFF). Recently collected EM300 and RESON8101 multibeam bathymetric data along with CHIRP subbottom data has unveiled some tectonic details within the TFZ. The GSZ runs along the offshore extension of the Northern Volcanic Rift Zone (NVRZ) and is made up of four left-stepping, en-echelon, NS-striking rift segments akin to those on land. Large GSZ earthquakes seem to be associated with lateral strike-slip faulting along ESE-striking fault planes. Fissure swarms transecting the offshore volcanic systems have also been subjected to right-lateral transformation along the spreading direction. As the Reykjanes Peninsula, the on land extension of the RR, the GSZ bears the characteristics of an oblique rift zone. The plate boundary segments connecting to the RR and KR are thus symmetrical with respect to the plate separation vector (105° ) and orientation of individual volcanic systems. The HFF has an overall strike of N65° W and can be traced continuously along its 75--80 km length, between the Theistareykir volcanic system within the NVRZ, across the central TFZ-graben, the Skjálfandi bay, and into the largest

  2. Free and forced vibration control of piezoelectric FGM plate subjected to electro-mechanical loading

    Science.gov (United States)

    Jadhav, Priyanka A.; Bajoria, Kamal M.

    2013-06-01

    This paper investigates the free and forced vibration analysis of a newly introduced metal based functionally graded (FG) plate integrated with a piezoelectric actuator and sensor at the top and bottom faces respectively. The material properties of the FG plate are assumed to be graded along the thickness direction according to a simple power law distribution in terms of the volume fraction of the constituents, while the Poisson ratio is assumed to be constant. The plate is simply supported at all edges. The finite element model is based on higher order shear deformation theory (HOST), the von Karman hypothesis and degenerated shell elements. The displacement component of the present model is expanded in Taylor’s series in terms of the thickness co-ordinate. The Hamilton principle is used to derive the equation of motion for the piezoelectric functionally graded material (FGM) plate. The free and forced vibration analysis of the simply supported piezoelectric FG plate is carried out to present the effect of the power law index and the piezoelectric layer. The present analysis is carried out on a newly introduced FGM, which is a mixture of aluminum and stainless steel. Stainless steel is a high strength material but it can rust in extreme cases, and aluminum does not rust but it is a low strength material. The FGM exhibits corrosion resistance as well as the high strength property in a single material. This new FGM will definitely help in the construction as well as the metal industry.

  3. Seismicity and seismotectonics of the diffusive Iberian/African plate boundary: Horseshoe Abyssal Plain and Gorringe Bank

    Science.gov (United States)

    Grevemeyer, Ingo; Lange, Dietrich; Matias, Luis

    2014-05-01

    In the area to the west of the Gibraltar Arc the plate boundary between Africa and Iberia is poorly defined. The deformation in the area is forced by the slow NW-SE convergence of 4 mm/yr between the oceanic domains of Iberia/Eurasia and Africa and is accommodated over a 200 km broad tectonically-active deformation zone. The region, however, is also characterized by large earthquakes and tsunamis, such as the 1969 Mw=7.9 Horseshoe Abyssal Plain earthquake and the November 1, 1755 Great Lisbon earthquake with an estimated magnitude of Mw~8.5. The exact location of the source of the 1755 Lisbon earthquake is still unknown. Recent work may suggest that the event occurred in the vicinity of the Horseshoe fault, an oblique thrust fault. However, estimates of tsunami arrival times suggested a source near the Gorringe Bank, a ~180 km-long and ~70 km-wide ridge that has a relieve of ~5000 m. Deep Sea Drilling (DSDP) and rock samples indicated that the bank is mainly composed of serpentinized peridotites with gabbroic intrusions, perhaps being created by overthrusting of the Horseshoe Abyssal Plain onto the Tagus Abyssal Plain in NW direction. Further, the Horseshoe Abyssal Plain is marked by the presence of compressive structures with a roughly NE-SW orientation and E-W trending, segmented, crustal-scale, strike slip faults that extend from the Gorringe Bank to the Gibraltar Arc in the eastern Gulf of Cadiz, which were called "South West Iberian Margin" or SWIM faults. The fault system may mark a developing Eurasia-Africa plate boundary. Two local seismic networks were operated in the area. First, a network of 14 ocean-bottom seismometers (OBS) was operated between April and October 2012 in the vicinity of the Horseshoe fault between 10°W to 11°W, and 35°50'N to 36°10'N. From October 2013 to March 2014 a second network of 15 OBS monitored seismicity at the Gorringe Bank. Both networks benefitted from seismic stations operated in Portugal. The first network provided in

  4. Seismicity of the diffusive Iberian/African plate boundary at the eastern terminus of the Azores-Gibraltar Transform fault

    Science.gov (United States)

    Lange, D.; Grevemeyer, I.; Matias, L. M.

    2014-12-01

    The plate boundary at the eastern terminus of the Azores-Gibraltar transform fault between Africa and Iberia is poorly defined. The deformation in the area is forced by the slow NW-SE convergence of 4 mm/yr between the oceanic domains of Iberia/Eurasia and Africa and is accommodated over a 200 km broad tectonically-active deformation zone. The region, however, is also characterized by large earthquakes, such as the 1969 Mw=7.9 Horseshoe event and the November 1, 1755 Great Lisbon earthquake with an estimated magnitude of Mw~8.5. The exact location of the source of the 1755 Lisbon earthquake is still unknown. Recent work may suggest that the event occurred in the vicinity of the Horseshoe fault, an oblique thrust fault. However, estimates of tsunami arrival times suggested a source near the Gorringe Bank, a ~180 km-long and ~70 km-wide ridge that has a relieve of ~5000 m. Deep Sea Drilling (DSDP) and rock samples indicated that the bank is mainly composed of serpentinized peridotites with gabbroic intrusions, perhaps being created by overthrusting of the Horseshoe Abyssal Plain onto the Tagus Abyssal Plain in NW direction. Further, the Horseshoe Abyssal Plain is marked by the presence of compressive structures with a roughly NE-SW orientation and E-W trending, segmented, crustal-scale, strike slip faults that extend from the Gorringe Bank to the Gibraltar Arc in the eastern Gulf of Cadiz, which were called "South West Iberian Margin" or SWIM faults. The fault system may mark a developing Eurasia-Africa plate boundary. Two local seismic networks were operated in the area. First, a network of 14 ocean-bottom seismometers (OBS) was operated between April and October 2012 in the vicinity of the Horseshoe fault between 10°W to 11°W, and 35°50'N to 36°10'N. From October 2013 to March 2014 a second network of 15 OBS monitored seismicity at the Gorringe Bank. Both networks benefitted from seismic stations operated in Portugal. The first network provided in the order of

  5. Dynamic forces between bubbles and surfaces and hydrodynamic boundary conditions.

    Science.gov (United States)

    Manor, Ofer; Vakarelski, Ivan U; Stevens, Geoffrey W; Grieser, Franz; Dagastine, Raymond R; Chan, Derek Y C

    2008-10-21

    A bubble attached to the end of an atomic force microscope cantilever and driven toward or away from a flat mica surface across an aqueous film is used to characterize the dynamic force that arises from hydrodynamic drainage and electrical double layer interactions across the nanometer thick intervening aqueous film. The hydrodynamic response of the air/water interface can range from a classical fully immobile, no-slip surface in the presence of added surfactants to a partially mobile interface in an electrolyte solution without added surfactants. A model that includes the convection and diffusion of trace surface contaminants can account for the observed behavior presented. This model predicts quantitatively different interfacial dynamics to the Navier slip model that can also be used to fit dynamic force data with a post hoc choice of a slip length.

  6. Water Release from Cold Serpentinized Forearc Mantle During Subduction Associated with Changes in Incoming Oceanic Plate Thermal Structure and Plate Boundary Kinematics: New Insights into Serpentinite Belts and Plate-Boundary Rheology

    Science.gov (United States)

    Kirby, Stephen

    2016-04-01

    Kirby, Wang, and Brocher (Earth Planets and Space, 2014) recently showed how the change in kinematics of the California margin from subduction motion to continental transform motion with the birth and growth of the San Andreas Fault System (SAFS) beginning at about 33 Ma BP likely led to a warming of the former forearc mantle and the release of water from serpentinized mantle by dehydration and a likely increase in fluid pressures along the SAFS. Such a mantle source of pressurized water gives insights into both the low sliding resistance for the SAFS and the mobilization and ascent of some serpentinized mantle peridotites through the crust. Thermal modeling by others has also shown that changes in the incoming plate age and subduction rate can also lead to warming of the forearc mantle during subduction. This development gives insights into the Mesozoic and Paleogene ages of emplacement of some, but not all, California serpentinites. Recent mineralogical and geochemical observations of serpentinite blocks in serpentinize mélange bodies in the San Francisco Bay Area (Uno and Kirby, 2014 AGU Meeting and Lewis and Kirby, 2015 AGU Meeting) suggest that these rocks sustained multiple stages of serpentinization that are broadly consistent with the model of Kirby et al. (2014). A new development comes from interpretation of investigations in the literature of localized late-stage silica-carbonate-water alteration of serpentinite bodies in California that this alteration occurred largely in Neogene time when the highest rates of water release from the former forearc mantle probably occurred. This presentation also suggests that the occurrence of serpentinite belts emplaced in Cenozoic time during changing plate-boundary kinematics, such as the Cenozoic closing of the Tethys Ocean bordering Eurasia by subduction and collision and arc reversal and decreasing convergence rates under the Greater Antilles and Colombia and New Guinea, may give insights into the serpentinite

  7. High resolution image of the Lithosphere-Asthenosphere Boundary of the subducting Nazca plate beneath northern Chile

    Science.gov (United States)

    Sodoudi, F.; Yuan, X.; Asch, G.; Kind, R.

    2010-12-01

    Results obtained from S and P receiver functions produced a clear image of the top and bottom of the subducting Nazca lithosphere beneath northern Chile. Using data from the teleseismic events recorded at 15 permanent IPOC (Integrated Plate boundary Observatory Chile) stations, we were able to obtain new constraints on the shape and thickness of the descending Nazca lithosphere. We observed the subducted crust of the Nazca plate at depths ranging from 40 km beneath the Coastal Cordillera down to 110 km beneath the Western Cordillera. We found significant along-strike variations in the geometry of the Nazca plate beneath northern Chile. On closer inspection, it appears that the oceanic Nazca plate is divided into two distinct segments as it descends beneath the continental South American plate. The transition from the relatively steeper and deeper slab to the north of 21° S to the flatter southern segment is shown reasonably clearly by our data. This feature could well be associated with variations in the curvature of the plate margin and the geometry of the Chile trench, which is mainly curved to the north of 21° S. We have also mapped the continental Moho of the South American plate at depths ranging between 60-70 km to the east of the Longitudinal Valley. Beneath the Coastal Cordillera, this boundary becomes invisible, probably due to the serpentinization of the forearc mantle wedge. The Lithosphere-Astheonsphere Boundary (LAB) of the subducted Nazca plate was clearly identified as a sharp boundary in the results obtained from the P and S receiver functions. The LAB lies at a depth of 80 km beneath the coastal area and dips from a depth of 100 km beneath the Coastal Cordillera to about 150 km underneath the Western Cordillera. High frequency PRF data enabled us to make confident estimates of the top and bottom of the Nazca lithosphere, which results in a lithospheric thickness of 57-60 km. In relation to the age of the Nazca plate, which is assumed to be ~ 50

  8. Outer layer effects in wind-farm boundary layers: Coriolis forces and boundary layer height

    Science.gov (United States)

    Allaerts, Dries; Meyers, Johan

    2015-11-01

    In LES studies of wind-farm boundary layers, scale separation between the inner and outer region of the atmospheric boundary layer (ABL) is frequently assumed, i.e., wind turbines are presumed to fall within the inner layer and are not affected by outer layer effects. However, modern wind turbine and wind farm design tends towards larger rotor diameters and farm sizes, which means that outer layer effects will become more important. In a prior study, it was already shown for fully-developed wind farms that the ABL height influences the power performance. In this study, we use the in-house LES code SP-Wind to investigate the importance of outer layer effects on wind-farm boundary layers. In a suite of LES cases, the ABL height is varied by imposing a capping inversion with varying inversion strengths. Results indicate the growth of an internal boundary layer (IBL), which is limited in cases with low inversion layers. We further find that flow deceleration combined with Coriolis effects causes a change in wind direction throughout the farm. This effect increases with decreasing boundary layer height, and can result in considerable turbine wake deflection near the end of the farm. The authors are supported by the ERC (ActiveWindFarms, grant no: 306471). Computations were performed on VSC infrastructiure (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government-department EWI.

  9. Active open boundary forcing using dual relaxation time-scales in downscaled ocean models

    Science.gov (United States)

    Herzfeld, M.; Gillibrand, P. A.

    2015-05-01

    Regional models actively forced with data from larger scale models at their open boundaries often contain motion at different time-scales (e.g. tidal and low frequency). These motions are not always individually well specified in the forcing data, and one may require a more active boundary forcing while the other exert less influence on the model interior. If a single relaxation time-scale is used to relax toward these data in the boundary equation, then this may be difficult. The method of fractional steps is used to introduce dual relaxation time-scales in an open boundary local flux adjustment scheme. This allows tidal and low frequency oscillations to be relaxed independently, resulting in a better overall solution than if a single relaxation parameter is optimized for tidal (short relaxation) or low frequency (long relaxation) boundary forcing. The dual method is compared to the single relaxation method for an idealized test case where a tidal signal is superimposed on a steady state low frequency solution, and a real application where the low frequency boundary forcing component is derived from a global circulation model for a region extending over the whole Great Barrier Reef, and a tidal signal subsequently superimposed.

  10. 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.

  11. The Quest for the Africa-Eurasia plate boundary West of the Strait of Gibraltar

    Science.gov (United States)

    Zitellini, N.

    2009-04-01

    A new swath bathymetry compilation of the Gulf of Cadiz Area and SW Iberia is presented. The new map is the result of a collaborative research performed after year 2000 by teams from 7 European countries and 14 research institutions. This new dataset allow for the first time to present and to discuss the missing link in the plate boundary between Eurasia and Africa in the Central Atlantic. A set of almost linear and sub parallel dextral strike-slip faults, the SWIM Faults (SWIM is the acronym of the ESF EuroMargins project "Earthquake and Tsunami hazards of active faults at the South West Iberian Margin: deep structure, high-resolution imaging and paleoseismic signature") was mapped using a the new swath bathymetry compilation available in the area. The SWIM Faults form a narrow band of deformation over a length of 600 km coincident with a small circle centred on the pole of rotation of Africa with respect to Eurasia, This narrow band of deformation connects the Gloria Fault to the Rif-Tell Fault Zone, two segments of the plate boundary between Africa and Eurasia. In addition, the SWIM faults cuts across the Gulf of Cadiz, in the Atlantic Ocean, where the 1755 Great Lisbon earthquake, M~8.5-8.7, and tsunami were generated, providing a new insights on its source location. SWIM Team: E. Gràcia (2), L. Matias (3), P. Terrinha (4), M.A. Abreu (5), G. DeAlteriis(6), J.P. Henriet (7), J.J. Dañobeitia (2), D.G. Masson (8), T. Mulder (9), R. Ramella (10), L. Somoza (11) and S. Diez (2) (2) Unitat de Tecnologia Marina (CSIC), Centre Mediterrani d'Investigacions Marines i Ambientals, Barcelona, Spain (3) Centro Geofísica da Universidade de Lisboa (CGUL, IDL), Lisboa, Portugal (4) National Institute for Engineering, Technology and Innovation (INETI, LATTEX), Departamento de Geologia Marinha, Amadora, Portugal (5) Estrutura de Missão para a Extensão da Plataforma Continental, Lisboa, Portugal (6) Geomare Sud IAMC, CNR, Napoli, Italy (7) Renard Centre of Marine Geology

  12. Evaluation of motion platform embedded with dual belt treadmill instrumented with two force plates.

    Science.gov (United States)

    Sinitski, Emily H; Lemaire, Edward D; Baddour, Natalie

    2015-01-01

    Motek Medical's Computer Aided Rehabilitation Environment (CAREN)-Extended system is a virtual environment primarily used in physical rehabilitation and biomechanical research. This virtual environment consists of a 180 degree projection screen used to display a virtual scene, a 12-camera motion capture system, and a six degree of freedom actuated platform equipped with a dual-belt treadmill and two force plates. The goal of this article was to investigate the performance characteristics associated with a "treadmill-motion platform" configuration and how system operation can affect the data collected. Platform static and dynamic characteristics were evaluated by translating or rotating the platform over progressively larger distances and comparing input and measured values. Treadmill belt speed was assessed with and without a person walking on the platform and at different orientations. Force plate measurements were examined when the treadmill was in operation, during ambulation, and over time to observe the baseline drift. Platform acceleration was dependent on the distance travelled and system settings. Treadmill speed variability was greatest at faster speeds. Force plate measurements were affected by platform and treadmill operation, contralateral impact forces during gait, and baseline drift. Knowledge of performance characteristics and their effect on outcome data is crucial for effective design of CAREN research protocols and rehabilitation scenarios.

  13. Surface constraints on the temporal and spatial evolution of the Farallon-Pacific-North America plate boundary

    Science.gov (United States)

    McQuarrie, N.; Oskin, M.

    2009-05-01

    Extension and volcanism are two surface derived data sets used to infer mantle processes back in time. We integrate two new large GIS-based datasets to create palinspastic restorations of extension and volcanism allowing us to readdress the relationship between plate-boundary deformation, intra-plate extension and magmatism in western North America. Using ArcGIS and custom software, we retrodeformed the NAVDat (North American Volcanic Database, navdat.geongrid.org) using the western North America reconstruction of McQuarrie and Wernicke (2005). We compare this data to strain rates calculated over a 50 km-grid forward- deformed from 36 Ma to present. With the deformed grid and palinspastically restored volcanic dataset we quantitatively compare rates of magmatism and deformation and evaluate the age, location, and migration of Cenozoic volcanic arcs. A first order conclusion from this study is that magmatism, throughout the Basin and Range, is primarily driven by plate boundary effects. The plate boundary effects include subduction and rollback of the Farallon plate, creation and expansion of slab windows as the Pacific plate intercepts the North American plate and re-establishment of the ancestral Cascade arc along the eastern margin of the Sierra Nevada at ˜ 15 Ma. Notable exceptions include the Yellowstone hotspot system along the northern boarder of our study area and late-stage (<8 Ma) passive, extension related asthenospheric upwelling that accompanied a thinning lithosphere along the eastern and western margins of the Basin and Range. The palinspastic reconstructions presented here highlight that the classic, high-angle, Basin and Range faulting that comprises most of the physiographic Basin and Range province commenced during a remarkably amagmatic period. These observations largely contradicts the active rifting model where magmatism triggers Basin and Range extension

  14. Multi-axis force sensing using a resonant composite piezoelectric plate: model and experiments

    Science.gov (United States)

    Castaño-Cano, Davinson; Grossard, Mathieu; Hubert, Arnaud

    2015-05-01

    Wrist force/torque sensors used in robotic applications increase the performances and flexibility of the automated tasks. They also offer new possibilities in the manufacturing process, where physical contact between the work-piece and environment is required. The wide spreading of these sensors is for now restricted by their features. As an alternative to the existing strain-gauges force sensors, this paper presents a resonant composite structure, which is sensitive to multiple components of force that are considered via the pre-stress effect. Structurally bonded piezoelectric patches are used to bring the structure to its resonance, which is shifted according to applied forces. The relationship between force and frequency shift is modelled considering the multi-physics of this smart structure. This model is built using Hamilton's principle and takes into account pre-stress phenomena. A finite element model (FEM) based on Mindlin theory for plates, has been derived from the analytical model. The FEM model is implemented in MATLAB and compared with commercial FE software. Finally, an experimental prototype validates the model, and shows that it is possible to measure multiple force-components with one single sensing element such as a plate.

  15. Plate tectonics and offshore boundary delimitation: Tunisia-Libya case at the International Court of Justice

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, D.J.

    1983-03-01

    Advances in the technology for exploiting resources of the oceans, particularly recovery of hydrocarbons and minerals in deep water, is benefiting a growing number of nations. At the same time, however, economic and political pressures have induced concern and there is now a much increased emphasis on jurisdiction to divide the offshore areas between the 132 coastal nations. Negotiations affect research operations at sea and, in consequence, marine scientists have been made aware of offshore problems as highlighted by the Law of the Sea Treaty (UNCLOS III) and complications arising from the legal versus scientific definitions of continental shelves and margins. The first major offshore boundary case of international scope where plate tectonics has constituted a significant argument is the one recently brought before the International Court of Justice by Libya and Tunisia concerning the delimitation of their continental shelves. Of the two parties, Libya placed the greatest emphasis on this concept as a means to determine natural prolongation of its land territory into and under the sea. Tunisia contested Libya's use of the whole of the African continental landmass as a reference unit; in Tunisia's view, considerations of geography, geomorphology, and bathymetry are at least as relevant as are those of geology. In its landmark judgment (February 1982) - which almost certainly will have far-reaching consequences in future such boundary delimitation cases - the court pronounced that It is the outcome, not the evolution in the long-distant past, which is of importance, and that it is the present-day configuration of the coasts and sea bed which are the main factors to be considered, not geology.

  16. A numerical modeling for the wave forcing of floating thin plate

    Energy Technology Data Exchange (ETDEWEB)

    Basirat Tabrizi, H. [Amirkabir Univ. of Technology, Mechanical Engineering Dept., Tehran (Iran, Islamic Republic of)]. E-mail: hbasirat@aut.ac.ir, H.Basirat@dal.ca; Kouchaki Motlaq, M. [Islamic Azad Univ., Dept. of Graduate Studies, Arak (Iran, Islamic Republic of)

    2004-07-01

    A finite difference scheme based on central difference, which is applicable to the thin plate floating on intermediate depth water subjected to wave force, is developed. The floating structure analyzed as a plate with unit width and expressed by an elastic bending theory. The fluid flow expressed as an incompressible, inviscid and steady that the potential theory can apply. Here, the water wave elevation assumed the same as the bending displacement structure at the interface. The distribution of the displacement amplitude of structure and the wave amplitude varies in a wavy pattern in the middle part and increases greatly near the edge of plate. The present method verified by comparing quantitatively with the reported experimental and theoretical results of others. (author)

  17. An immersed boundary model of the cochlea with parametric forcing

    CERN Document Server

    Ko, William

    2015-01-01

    The cochlea or inner ear has a remarkable ability to amplify sound signals. This is understood to derive at least in part from some active process that magnifies vibrations of the basilar membrane (BM) and the cochlear partition in which it is embedded, to the extent that it overcomes the effect of viscous damping from the surrounding cochlear fluid. Many authors have associated this amplification ability to some type of mechanical resonance within the cochlea, however there is still no consensus regarding the precise cause of amplification. Our work is inspired by experiments showing that the outer hair cells within the cochlear partition change their lengths when stimulated, which can in turn cause periodic distortions of the BM and other structures in the cochlea. This paper investigates a novel fluid-mechanical resonance mechanism that derives from hydrodynamic interactions between an oscillating BM and the surrounding cochlear fluid. We present a model of the cochlea based on the immersed boundary method...

  18. Chlorine isotope geochemistry of Icelandic thermal fluids: Implications for geothermal system behavior at divergent plate boundaries

    Science.gov (United States)

    Stefánsson, Andri; Barnes, Jaime D.

    2016-09-01

    The chlorine isotope composition of thermal fluids from Iceland were measured in order to evaluate the source of chlorine and possible chlorine isotope fractionation in geothermal systems at divergent plate boundaries. The geothermal systems studied have a wide range of reservoir temperatures from 40 to 437 °C and in-situ pH of 6.15 to 7.15. Chlorine concentrations range from 5.2 to 171 ppm and δ37 Cl values are -0.3 to + 2.1 ‰ (n = 38). The δ37 Cl values of the thermal fluids are interpreted to reflect the source of the chlorine in the fluids. Geothermal processes such as secondary mineral formation, aqueous and vapor speciation and boiling were found to have minimal effects on the δ37 Cl values. However, further work is needed on incorporation of Cl into secondary minerals and its effect on Cl isotope fractionation. Results of isotope geochemical modeling demonstrate that the range of δ37 Cl values documented in the natural thermal fluids can be explained by leaching of the basaltic rocks by meteoric source water under geothermal conditions. Magmatic gas partitioning may also contribute to the source of Cl in some cases. The range of δ37 Cl values of the fluids result mainly from the large range of δ37 Cl values observed for Icelandic basalts, which range from -0.6 to + 1.2 ‰.

  19. Numerical-perturbation technique for stability of flat-plate boundary layers with suction

    Science.gov (United States)

    Reed, H. L.; Nayfeh, A. H.

    1986-01-01

    A numerical-perturbation scheme is proposed for determining the stability of flows over plates with suction through a finite number of porous suction strips. The basic flow is calculated as the sum of the Blasius flow and closed-form linearized triple-deck solutions of the flow due to the strips. A perturbation technique is used to determine the increment a(ij) in the complex wavenumber at a given location x(j) due to the presence of a strip centered at x(i). The end result is a set of influence coefficients that can be used to determine the growth rates and amplification factors for any suction levels without repeating the calculations. The numerical-perturbation results are verified by comparison with interacting boundary layers for the case of six strips and the experimental data of Reynolds and Saric for single- and multiple-strip configurations. The influence coefficient form of the solution suggests a scheme for optimizing the strip configuration. The results show that one should concentrate the suction near branch I of the neutral stability curve, a conclusion verified by the experiments.

  20. HOT WIRE MEASUREMENT OF TURBULENT BOUNDARY LAYER ON A FILM COOLING PLATE WITH DIFFUSION HOLES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This study experimentally investigated the film cooling flowfield of a single row of diffusion holes, from which the secondary air flow was injected into a turbulent boundary layer with zero pressure gradient on a flat plate. Circular-shaped holes were also tested as a basis for comparison. All the holes were inclined downstream at 35° with respect to the surface and the lateral spacing between the holes was 3 diameters of the hole. The mainstream velocity was maintained at 17 m/s and the Reynolds number based on the injection hole diameter was almost 11000. The density ratio of the jet to mainstream was 1.0, and the jet-to-mainstream velocity ratios M were 0.5 and 1.5. Normal-type and X-type hot wire anemometries were used to measure the streamwise mean velocity and its components, the normal and shear turbulent Reynolds stress components at the locations from the backward edge of the injection hole to 25 diameters downstream.

  1. Conformal field theory of critical Casimir forces between surfaces with alternating boundary conditions in two dimensions

    Science.gov (United States)

    Dubail, J.; Santachiara, R.; Emig, T.

    2017-03-01

    Systems as diverse as binary mixtures and inclusions in biological membranes, and many more, can be described effectively by interacting spins. When the critical fluctuations in these systems are constrained by boundary conditions, critical Casimir forces (CCF) emerge. Here we analyze CCF between boundaries with alternating boundary conditions in two dimensions, employing conformal field theory (CFT). After presenting the concept of boundary changing operators, we specifically consider two different boundary configurations for a strip of critical Ising spins: (I) alternating equi-sized domains of up and down spins on both sides of the strip, with a possible lateral shift, and (II) alternating domains of up and down spins of different size on one side and homogeneously fixed spins on the other side of the strip. Asymptotic results for the CCF at small and large distances are derived. We introduce a novel modified Szegö formula for determinants of real antisymmetric block Toeplitz matrices to obtain the exact CCF and the corresponding scaling functions at all distances. We demonstrate the existence of a surface renormalization group flow between universal force amplitudes of different magnitude and sign. The Casimir force can vanish at a stable equilibrium position that can be controlled by parameters of the boundary conditions. Lateral Casimir forces assume a universal simple cosine form at large separations.

  2. Electrical characterization of grain boundaries of CZTS thin films using conductive atomic force microscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Muhunthan, N.; Singh, Om Pal [Compound Semiconductor Solar Cell, Physics of Energy Harvesting Division, New Delhi 110012 (India); Toutam, Vijaykumar, E-mail: toutamvk@nplindia.org [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Singh, V.N., E-mail: singhvn@nplindia.org [Compound Semiconductor Solar Cell, Physics of Energy Harvesting Division, New Delhi 110012 (India)

    2015-10-15

    Graphical abstract: Experimental setup for conducting AFM (C-AFM). - Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) thin film was grown by reactive co-sputtering. • The electronic properties were probed using conducting atomic force microscope, scanning Kelvin probe microscopy and scanning capacitance microscopy. • C-AFM current flow mainly through grain boundaries rather than grain interiors. • SKPM indicated higher potential along the GBs compared to grain interiors. • The SCM explains that charge separation takes place at the interface of grain and grain boundary. - Abstract: Electrical characterization of grain boundaries (GB) of Cu-deficient CZTS (Copper Zinc Tin Sulfide) thin films was done using atomic force microscopic (AFM) techniques like Conductive atomic force microscopy (CAFM), Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM). Absorbance spectroscopy was done for optical band gap calculations and Raman, XRD and EDS for structural and compositional characterization. Hall measurements were done for estimation of carrier mobility. CAFM and KPFM measurements showed that the currents flow mainly through grain boundaries (GB) rather than grain interiors. SCM results showed that charge separation mainly occurs at the interface of grain and grain boundaries and not all along the grain boundaries.

  3. Horizontal versus vertical plate motions

    Directory of Open Access Journals (Sweden)

    M. Cuffaro

    2006-07-01

    Full Text Available We review both present and past motions at major plate boundaries, which have the horizontal component in average 10 to 100 times faster (10–100 mm/yr than the vertical component (0.01–1 mm/yr in all geodynamic settings. The steady faster horizontal velocity of the lithosphere with respect to the upward or downward velocities at plate boundaries supports dominating tangential forces acting on plates. This suggests a passive role of plate boundaries with respect to far field forces determining the velocity of plates. The forces acting on the lithosphere can be subdivided in coupled and uncoupled, as a function of the shear at the lithosphere base. Higher the asthenosphere viscosity, more significant should be the coupled forces, i.e., the mantle drag and the trench suction. Lower the asthenosphere viscosity, more the effects of uncoupled forces might result determinant, i.e., the ridge push, the slab pull and the tidal drag. Although a combination of all forces acting on the lithosphere is likely, the decoupling between lithosphere and mantle suggests that a torque acts on the lithosphere independently of the mantle drag. Slab pull and ridge push are candidates for generating this torque, but, unlike these boundary forces, the advantage of the tidal drag is to be a volume force, acting simultaneously on the whole plates, and being the decoupling at the lithosphere base controlled by lateral variations in viscosity of the low-velocity layer.

  4. The Baja California Borderland and the Neogene Evolution of the Pacific-North American Plate Boundary

    Science.gov (United States)

    Fletcher, J. M.; Eakins, B. W.

    2001-12-01

    New observational data on Neogene faulting in the borderland of Baja California places important constraints on tectonic models for the evolution of the Pacific-North American (P-NA) plate boundary and rifting in the Gulf of California. Neogene faults in the borderland range from strike slip to normal slip and accommodate integrated transtension. Most have east-facing escarpments and likely reactivate the former east-dipping accretionary complex. Numerous lines of evidence indicate that Neogene faults are still active and accomplish a significant component ( ~1-5 mm/yr) of Pacific-North American shearing. Quaternary volcanoes are found offshore and along the Pacific coastal margin, Quaternary marine terraces are warped and uplifted as high as 200 masl. Many of the offshore faults have fresh escarpments and cut Holocene sediments. Extensive arrays of Quaternary fault scarps are found throughout the coastal region and in Bahia Magdalena they are clearly associated with major faults that bound recently uplifted islands. A prominent band of seismicity follows the coast and eight earthquakes (Ms>5.0) were teleseismically recorded between 1973 and 1998. This evidence for active shearing indicates that the Baja microplate has not yet been completely transferred to the Pacific plate. The best lithologic correlation that can be used to define the total Neogene slip across the borderland faults is the offset between the Magdalena submarine fan and its Baja source terrane. The distal facies of the fan drilled during DSDP leg 63 is dominated by mudstone and siltstone that contain reworked Paleogene cocoliths derived from strata correlative with the Tepetate formation found throughout the borderland and fine-grained sandstone derived from a source terrane of granitoid basement. The Middle Miocene La Calera formation of the Cabo trough is one of many granitoid-clast syn-rift alluvial deposits that could form the continental counterpart of the submarine fan near the mouth of the

  5. A wearable force plate system for the continuous measurement of triaxial ground reaction force in biomechanical applications

    Science.gov (United States)

    Liu, Tao; Inoue, Yoshio; Shibata, Kyoko

    2010-08-01

    The ambulatory measurement of ground reaction force (GRF) and human motion under free-living conditions is convenient, inexpensive and never restricted to gait analysis in a laboratory environment and is therefore much desired by researchers and clinical doctors in biomedical applications. A wearable force plate system was developed by integrating small triaxial force sensors and three-dimensional (3D) inertial sensors for estimating dynamic triaxial GRF in biomechanical applications. The system, in comparison to existent systems, is characterized by being lightweight, thin and easy-to-wear. A six-axial force sensor (Nitta Co., Japan) was used as a verification measurement device to validate the static accuracy of the developed force plate. To evaluate the precision during dynamic gait measurements, we compared the measurements of the triaxial GRF and the center of pressure (CoP) by using the developed system with the reference measurements made using a stationary force plate and an optical motion analysis system. The root mean square (RMS) differences of the two transverse components (x- and y-axes) and the vertical component (z-axis) of the GRF were 4.3 ± 0.9 N, 6.0 ± 1.3 N and 12.1 ± 1.1 N, respectively, corresponding to 5.1 ± 1.1% and 6.5 ± 1% of the maximum of each transverse component and 1.3 ± 0.2% of the maximum vertical component of GRF. The RMS distance between the two systems' CoP traces was 3.2 ± 0.8 mm, corresponding to 1.2 ± 0.3% of the length of the shoe. Moreover, based on the results of the assessment of the influence of the system on natural gait, we found that gait was almost never affected. Therefore, the wearable system as an alternative device can be a potential solution for measuring CoP and triaxial GRF in non-laboratory environments.

  6. Effect of volumetric electromagnetic forces on shock wave structure of hypersonic air flow near plate

    Science.gov (United States)

    Fomichev, Vladislav; Yadrenkin, Mikhail; Shipko, Evgeny

    2016-10-01

    Summarizing of experimental studies results of the local MHD-interaction at hypersonic air flow near the plate is presented. Pulsed and radiofrequency discharge have been used for the flow ionization. It is shown that MHD-effect on the shock-wave structure of the flow is significant at test conditions. Using of MHD-interaction parameter enabled to defining characteristic modes of MHD-interaction by the force effect: weak, moderate and strong.

  7. COMPARISON OF THREE DIFFERENT IMAGE FORCES FOR ACTIVE CONTOURS ON ABDOMINAL IMAGE BOUNDARY DETECTION

    Directory of Open Access Journals (Sweden)

    Cherry Galatia Ballangan

    2005-01-01

    Full Text Available Active contour, or snake, is an energy minimizing spline that is useful in image boundary detection. Active contours are stimulated by internal forces, image forces and external forces which maintain the shape of the contours while attract the contours to some desired features, usually edges. Problems in implementing active contours such as convergence and initialization have motivated researchers to modify image forces of the active contours. This paper presents a comparative study among three different image forces: traditional snakes, balloon and gradient vector flow (GVF. The study is validated by experiments on abdominal image boundaries detection. These lead to the conclusion that GVF gives the most appropriate results among the other approaches.

  8. Porosity-dependent nonlinear forced vibration analysis of functionally graded piezoelectric smart material plates

    Science.gov (United States)

    Qing Wang, Yan; Zu, Jean W.

    2017-10-01

    This work investigates the porosity-dependent nonlinear forced vibrations of functionally graded piezoelectric material (FGPM) plates by using both analytical and numerical methods. The FGPM plates contain porosities owing to the technical issues during the preparation of FGPMs. Two types of porosity distribution, namely, even and uneven distribution, are considered. A modified power law model is adopted to describe the material properties of the porous FGPM plates. Using D’Alembert’s principle, the out-of-plane equation of motion is derived by taking into account the Kármán nonlinear geometrical relations. After that, the Galerkin method is used to discretize the equation of motion, resulting in a set of ordinary differential equations with respect to time. These ordinary differential equations are solved analytically by employing the harmonic balance method. The approximate analytical results are verified by using the adaptive step-size fourth-order Runge–Kutta method. By means of the perturbation technique, the stability of approximate analytical solutions is examined. An interesting nonlinear broadband vibration phenomenon is detected in the FGPM plates with porosities. Nonlinear frequency-response characteristics of the present smart structures are investigated for various system parameters including the porosity type, the porosity volume fraction, the electric potential, the external excitation, the damping and the constituent volume fraction. It is found that these parameters have significant effects on the nonlinear vibration characteristics of porous FGPM plates.

  9. The boundaries of public action: arranged and forced marriages

    Directory of Open Access Journals (Sweden)

    Daniela Danna

    2013-07-01

    Full Text Available In this article I deal with the political and cultural dilemma of the distinction between arranged and forced or imposed marriages. After a review of the literature, interviews collected in 2009 in the Italian region of Emilia-Romagna are used to illustrate the views of the participants to the research. With the help of the theoretical tool of cultural materialism, I argue that the question can be approached from two different points of view: on the one hand, the distinction is clear as it is based on the recognition (even a late one of an imposition by physical or psychological violence on the part of the subject; on the other hand sociological analysis of the process of construction and of expression of consent reveals a vast gray area that is object of debate in the scientific literature as well as in everyday life. Only the first definition of forced marriage, the subjective one, can justify the start of a concrete intervention by the public authorities - but this cannot stop the debate on the actual value of the consent given in many cases of marriages.

  10. Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica)

    Science.gov (United States)

    Malusà, Marco G.; Faccenna, Claudio; Baldwin, Suzanne L.; Fitzgerald, Paul G.; Rossetti, Federico; Balestrieri, Maria Laura; Danišík, Martin; Ellero, Alessandro; Ottria, Giuseppe; Piromallo, Claudia

    2015-06-01

    Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary.

  11. Vertical tectonics at a continental crust-oceanic plateau plate boundary zone: Fission track thermochronology of the Sierra Nevada de Santa Marta, Colombia

    Science.gov (United States)

    Villagómez, Diego; Spikings, Richard; Mora, AndréS.; GuzmáN, Georgina; Ojeda, GermáN.; CortéS, Elizabeth; van der Lelij, Roelant

    2011-08-01

    The topographically prominent Sierra Nevada de Santa Marta forms part of a faulted block of continental crust located along the northern boundary of the South American Plate, hosts the highest elevation in the world (˜5.75 km) whose local base is at sea level, and juxtaposes oceanic plateau rocks of the Caribbean Plate. Quantification of the amount and timing of exhumation constrains interpretations of the history of the plate boundary, and the driving forces of rock uplift along the active margin. The Sierra Nevada Province of the southernmost Sierra Nevada de Santa Marta exhumed at elevated rates (≥0.2 Km/My) during 65-58 Ma in response to the collision of the Caribbean Plateau with northwestern South America. A second pulse of exhumation (≥0.32 Km/My) during 50-40 Ma was driven by underthrusting of the Caribbean Plate beneath northern South America. Subsequent exhumation at 40-25 Ma (≥0.15 Km/My) is recorded proximal to the Santa Marta-Bucaramanga Fault. More northerly regions of the Sierra Nevada Province exhumed rapidly during 26-29 Ma (˜0.7 Km/My). Further northward, the Santa Marta Province exhumed at elevated rates during 30-25 Ma and 25-16 Ma. The highest exhumation rates within the Sierra Nevada de Santa Marta progressed toward the northwest via the propagation of NW verging thrusts. Exhumation is not recorded after ˜16 Ma, which is unexpected given the high elevation and high erosive power of the climate, implying that rock and surface uplift that gave rise to the current topography was very recent (i.e., ≤1 Ma?), and there has been insufficient time to expose the fossil apatite partial annealing zone.

  12. The forced vibrational response of a rectangular parallelepiped with rigid-lubricated boundaries

    Science.gov (United States)

    Hill, E. v. K.; Egle, D. M.

    1982-01-01

    The Green function for a rectangular parallelepiped with rigid-lubricated boundaries is developed by a normal mode approach, the free vibration solutions being used. Explicit solutions are presented for a concentrated impulse, which serves as a model for an acoustic emission stress wave, and for a concentrated step force. Numerical results for short times show good agreement with the infinite space solution. Analogous solutions are developed for the inverse boundary conditions.

  13. Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

    Science.gov (United States)

    Gonçalves da Silva, Hugo; Bezzeghoud, Mourad; Biagi, Pier; Namorado Rosa, Rui; Salgueiro da Silva, Manuel; Caldeira, Bento; Heitor Reis, Artur; Borges, José Fernando; Tlemçani, Mouhaydine; Manso, Marco

    2010-05-01

    This paper presents a future research plan that aims to monitor Seismo-electromagnetic (SEM) phenomena in the western part of the Eurasia-Nubia plate boundary (WENP). This region has a significant tectonic activity [1] combined with relatively low electromagnetic noise levels and for that reason presents the possibility to perform high quality SEM measurements. Further, it is known that low-frequency [ultra (ULF), very (VLF), and low-frequencies (LF)] electromagnetic (EM) waves produce more convincing earthquake precursors (compared to higher frequencies) because of less contamination, large skin depth, and low attenuation [2]. Thus, two SEM effects will be considered: ULF electromagnetic field emissions [3], and VLF/LF radio broadcastings [4]. With respect to the ULF measurements, as a start, three ULF sensors are planned to be installed in the South of Iberian Peninsula supported by the existing networks of seismic research stations. Subsequent development of this initial plan could result in the implementation of a lager ULF monitoring network not only in the Iberian Peninsula, but also in the rest of Europe. Possible integration in the SEGMA array is now under consideration. Another perspective is to use a portable station to track seismic events. Regarding the VLF/LF radio broadcastings, a receiver is planned to be mounted in University of Évora. Radio signals from up to 10 transmitters (in these bands) of interest to study the seismic activity in the WENP region will be monitored. Actually, the radio path from the transmitter to the receiver should cross the epicentral area, therefore two possible transmitters are the ones installed in Monaco (France) and Sicily (Italy). Furthermore, the system will integrate the INFREP network and in this context it will not be restricted to WENP region. With the development of these research plans we aim to collect novel SEM data emerging from the seismic activity in the WENP region. We expect to address the time

  14. Laminar Forced Convection Heat and Mass Transfer of Humid Air across a Vertical Plate with Condensation

    Institute of Scientific and Technical Information of China (English)

    李成; 李俊明

    2011-01-01

    Condensation of humid air along a vertical plate was numerically investigated, with the mathematical model built on the full boundary layer equations and the film-wise condensation assumption. The velocity, heat and mass transfer characteristics at the gas-liquid interface were numerical analyzed and the results indicated that it was not reasonable to neglect the condensate film from the point of its thickness only. The condensate film thickness, interface temperature drop and the interface tangential velocity affect the physical fields weakly. However, the subcooling and the interface normal velocity were important factors to be considered before the simplification was made. For higher wall temperature, the advective mass transfer contributed much to the total mass transfer. Therefore, the boundary conditions were the key to judge the rationality of neglecting the condensate film for numerical solutions. The numerical results were checked by comparing with experiments and correlations.

  15. Study of Transition from Laminar to Turbulent Boundary Layer on a Tilted Flat Plate Using Heat Transfer Measurements

    Institute of Scientific and Technical Information of China (English)

    E.Sanz; C.Nicot; R.Point; F.Plaza

    2007-01-01

    The boundary layer transition over a flat tilted plate has been studied by means of heat transfer measurements. A heat flux sensor has been developed, in order to measure the efficiency of convective heat transfer for various types of surfaces or flows. Its operation at constant temperature allows direct and fast measurements of heat flux. The present paper reports the development of the sensor and presents its application to the study of transition in a boundary layer depending on the angle of incidence of the external flow. An exponential relationship between critical Reynolds number and pressure gradient parameter has been found.

  16. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  17. A radial distribution function-based open boundary force model for multi-centered molecules

    KAUST Repository

    Neumann, Philipp

    2014-06-01

    We derive an expression for radial distribution function (RDF)-based open boundary forcing for molecules with multiple interaction sites. Due to the high-dimensionality of the molecule configuration space and missing rotational invariance, a computationally cheap, 1D approximation of the arising integral expressions as in the single-centered case is not possible anymore. We propose a simple, yet accurate model invoking standard molecule- and site-based RDFs to approximate the respective integral equation. The new open boundary force model is validated for ethane in different scenarios and shows very good agreement with data from periodic simulations. © World Scientific Publishing Company.

  18. Automated boundary interaction force control of micromanipulators with in situ applications to microsurgery

    Science.gov (United States)

    Eslami, Sohrab; Jalili, Nader

    2012-12-01

    Most recent works on miniature tasks are concentrated on developing tools to take advantage of the visual servoing feedback to control the ultra-small interaction forces. This paper spans an extensive platform for automatic controlling of boundary interaction forces with high precision in the level of micro/nano-Newton with extensive micro/nanoengineering applications such as the microsurgery. To this end, a comprehensive piezoresistive microcantilever (PMC) model considering the shear deformation and rotary inertia effects treating as the distributed-parameters model along with the Hertzian contact force is presented. The purpose of considering the Hertzian contact force model is to investigate the dynamic response of the interaction force between the microcantilever's tip and the specimen. Afterward, a control platform is introduced to automatically manipulate the PMC to follow an ideal micro/nano-interaction force. By using the integrated PMC with the micromanipulator and a digital signal processor, an intuitive programming code is written to incorporate the micromanipulator and the controller in a real-time framework. To calibrate and verify the induced voltage in the PMC, a self-sensing experiment on the piezoelectric microcantilever is carried out to warrant the calibration procedure. Some experiments are established to affirm the validity of the proposed control for the autonomous real-time tasks on the boundary interaction force control. Unlike the conventional research studies, the measured force here contributes as the feedback source in contrast to the vision feedback while force sensors possess more precision, productivity and small size. This technique has several potential applications listed but not limited to the micro/nanomanipulation, developing artificial biological systems (e.g., fabricating hydrogel for the scaffold), and medicine such as microsurgery. As a result, using the proposed platform, we are able to manipulate and control the boundary

  19. The EarthScope Plate Boundary Observatory (PBO) Facility: Innovations, Transformations, and Impact

    Science.gov (United States)

    Jackson, M. E.; Mencin, D.; Feaux, K.

    2013-12-01

    The word 'transformation' is not used lightly in science. However, the transformative nature of the EarthScope Plate Boundary Observatory facility on the science community is large and measurable. The impact of the creation, execution and delivery of the PBO resulted in radical changes in the way the geodesy community views permanent, continuously operating (and often) real-time GPS and strain networks, open data policies, and the ability for consortium based facilities, such as UNAVCO, to manage and deliver on large National Science Foundation investments. Our presentation will explore these innovations and transformations from the community, facility, and science perspectives. In the genesis of the EarthScope proposal there was a distinct shift away from the PBO being managed and constructed by prominent PI's within the community to a vesting of the responsibility and authority in UNAVCO to execute on behalf of the entire community. This tipping away from individual PI concerns towards a communal behavior allowed the construction of a facility based on broad input from, and equal access for, any member of the geodesy community. The open and transparent nature of EarthScope, including the open data policy for both facility and PI derived data was truly transformative. One of the key tenants of the PBO was strict adherence to not redesigning unless absolutely necessary. For example PBO monumentation and data processing practices were adopted wholesale from the SCIGN project, while the station selection, project management, permitting practices, data downloading, metadata, and, data communications were refactored for optimum use for the broader geodesy community and to scale with the large geography that confronted PBO. The PBO strainmeter network, one of the largest in the world, started by looking at the procedures of 30 years of heterogeneous installations around the word then crafted, created, and amalgamated new drilling, grouting, installation, and data

  20. Update on Plate Boundary Observatory (PBO) Activities in the PNW Region

    Science.gov (United States)

    Austin, K. E.; Fengler, K.; Doelger, S.

    2007-12-01

    The Plate Boundary Observatory (PBO), which is part of the larger NSF-funded EarthScope project, is nearing the end of year 3 of the installation phase of 852 continuously operating GPS stations in the Western United States. The Pacific Northwest (PNW) region will install 134 continuous GPS stations by the end of September 2008. The sites are distributed along the fore and back-arc of the Cascadia Subduction Zone and at Mt. St. Helens. At the end of September 2007, the PNW region will be several stations short of its installation goal of 110 GPS stations, mostly due to an unusually early and high danger wildfire season. The scientific priority during this past year was to concentrate installations in the Oregon back arc region, the Southwest Oregon fore arc region and the Idaho panhandle. In the last year UNAVCO has added 10 stations to the Pacific Northwest region, raising the number of stations from 124 to 134. The majority of these stations are located within the fore and back arc regions of Southern Oregon. In addition the UNAVCO installed its first building mounted site within a difficult area along the Southwest Oregon coast. UNAVCO will install its remaining 24 new continuous GPS stations in the Pacific Northwest in year 5. The remaining stations are distributed throughout the region, and comprise a mix of standard monuments, and strainmeter collocations. Our goal is to have all stations installed by August 31 2008. Reconnaissance work for all of the GPS sites have been completed, and have had permits submitted.

  1. Low-latency high-rate GPS data from the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Anderson, G.; Jackson, M.; Meertens, C.; Stark, K.

    2007-05-01

    Real-time processing of high rate GPS data can give precise (e.g., 5-10 mm for data recorded once per second) recordings of rapid volcanic and seismic deformation. GPS is also an inertial sensor that records ground displacement with very high dynamic range, which allows the use of high rate GPS as a strong-motion seismometer. Such processing applied to low-latency streams of high sample rate GPS provide an emerging tool for earthquake, volcano, and tsunami geodesy and early warning. UNAVCO, as part of the EarthScope Plate Boundary Observatory project, is developing a system to provide such streams from some PBO and other UNAVCO-operated GPS stations, which we call UStream. UStream will be based on the Ntrip standard, a widely used protocol for streaming GNSS data over the Internet. Remote GPS stations will provide a stream of BINEX data at 1 sample/sec to an Ntrip server at UNAVCO's Boulder offices, while at the same time recording data locally in the event of communications failure. Once in Boulder, the data will be forked into three output streams: BINEX files stored at the UNAVCO archive and streams of data in BINEX and RTCM format. These data will flow to an Ntrip broadcaster that will distribute data to Ntrip clients, which can be anything from epoch-by-epoch processing systems to external data archiving systems. Data will flow through this system with no artificial latency and will be freely available to the community for use in scientific research.

  2. EarthScope Plate Boundary Observatory, Southwest Region - Communications, Challenges, and Cooperation

    Science.gov (United States)

    Turner, R. C.; Mann, D.; Walls, C. P.; Basset, A.; Lawrence, S.; Berglund, H. T.

    2015-12-01

    The Southwest Region of the EarthScope Plate Boundary Observatory is engaged in efforts to expand capabilities and renovate the network. These efforts include GNSS hardware modernization (in cooperation with state and local agencies), communications upgrades that improve data throughput and decrease recurring costs, co-location of prototype instruments for use in earthquake early warning, and working to ensure consistent high-quality data in the face of radio spectrum encroachment.The Global Positioning System (GPS) is but one of a growing number of global navigation satellite systems (GNSS) with the potential to improve geodetic observations. In addition to strategic deployment of GNSS-capable hardware, the Southwest region is currently developing an agreement with Caltrans to augment the network with GNSS systems at about a dozen stations. The upgrades will consist of a number of Caltrans-provided GLONASS-ready receivers and project is scheduled for completion by early 2016.The Southwest Region has continued to upgrade and build new radio networks to improve dependability, monitoring, and data download rates (including transfers of high-rate data). Here, we highlight one such network near Hollister, CA, which eliminated several cellular modems and improved reliability.UNAVCO and Scripps have been working in collaboration to augment a subset of GPS stations with low-cost strong-motion sensors for use in Earthquake Early Warning systems. To date, 21 PBO stations have been upgraded with MEMS accelerometers along the San Andreas and San Jacinto Faults in Northern and Southern California, 15 of which stream data to UNAVCO in real time.As the use of the radio frequency spectrum increases, PBO faces more radio frequency interference (RFI) in our data communications networks; in addition, RFI issues are beginning to impact GNSS data collection. Here we report on a PBO site suspected of suffering from RFI and discuss briefly mitigation efforts to minimize these effects.

  3. High-Resolution LiDAR Topography of the Plate-Boundary Faults in Northern California

    Science.gov (United States)

    Prentice, C. S.; Phillips, D. A.; Furlong, K. P.; Brown, A.; Crosby, C. J.; Bevis, M.; Shrestha, R.; Sartori, M.; Brocher, T. M.; Brown, J.

    2007-12-01

    GeoEarthScope acquired more than 1500 square km of airborne LiDAR data in northern California, providing high-resolution topographic data of most of the major strike-slip faults in the region. The coverage includes the San Andreas Fault from its northern end near Shelter Cove to near Parkfield, as well as the Rodgers Creek, Maacama, Calaveras, Green Valley, Paicines, and San Gregorio Faults. The Hayward fault was added with funding provided by the US Geological Survey, the City of Berkeley, and the San Francisco Public Utilities Commission. Data coverage is typically one kilometer in width, centered on the fault. In areas of particular fault complexity the swath width was increased to two kilometers, and in selected areas swath width is as wide as five kilometers. A five-km-wide swath was flown perpendicular to the plate boundary immediately south of Cape Mendocino to capture previously unidentified faults and to understand off-fault deformation associated with the transition zone between the transform margin and the Cascadia subduction zone. The data were collected in conjunction with an intensive GPS campaign designed to improve absolute data accuracy and provide quality control. Data processing to classify the LiDAR point data by return type allows users to filter out vegetation and produce high-resolution DEMs of the ground surface beneath forested regions, revealing geomorphic features along and adjacent to the faults. These data will allow more accurate mapping of fault traces in regions where the vegetation canopy has hampered this effort in the past. In addition, the data provide the opportunity to locate potential sites for detailed paleoseismic studies aimed at providing slip rates and event chronologies. The GeoEarthScope LiDAR data will be made available via an interactive data distribution and processing workflow currently under development.

  4. 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.

  5. Monitoring the northern Chile megathrust with the Integrated Plate boundary Observatory Chile (IPOC)

    Science.gov (United States)

    Schurr, Bernd; Asch, Günter; Cailleau, Beatrice; Diaz, Guillermo Chong; Barrientos, Sergio; Vilotte, Jean-Pierre; Oncken, Onno

    2010-05-01

    thousand aftershocks during the following week using waveform cross-correlation and the double-difference algorithm. Aftershocks reveal that rupture during this earthquake was confined to the deeper part (35 - 55 km depth) of the seismogenic coupling zone, except near the Mejillones peninsula that marks rupture termination in the south. Here earthquake activity reaches to depths of 20 km and even shallower, possibly indicating upper plate activation. The sequence also features an M 6.8 earthquake that broke the oceanic slab on an almost vertical plane at the down-dip end of the megathrust rupture. Confrontation with the aftershock distribution of the 1995 M 8.0 Antofagasta earthquake on the adjoining southern segment reveals an intriguing mirror symmetry with an axis crossing the Mejillones peninsula, emphasizing the penisula's significance as a segment boundary. Since then activity inside the remaining seismic gap to the north picked up with three earthquakes exceeding magnitude 6, maybe heralding the next great rupture.

  6. Force response of actively deformed polymer microdroplets: dependence on the solid/liquid boundary condition

    Science.gov (United States)

    Heppe, Jonas; McGraw, Joshua D.; Bennewitz, Roland; Jacobs, Karin

    2015-03-01

    In fluid dynamics, the solid/liquid boundary condition can play a major role in the flow behavior of a liquid. For example, in the dewetting of identical polymer films on weak slip or strong slip substrates, large qualitative and quantitative differences are observed. Therefore, when applying an external load to a liquid resting on such substrates, the measured reaction forces and the ensuing flow should also depend on the boundary condition. We present atomic force microscopy measurements in which the reaction force of a cantilever is measured as the tip pierces liquid polymer micron sized droplets and films. These indentations are done on substrates with tuned slip. Accessing the size, depth and rate dependence of the resulting force distance curves, we show an influence of the slip condition on the dissipated energy and adhesion.

  7. Differences in the efficacy of climate forcings explained by variations in atmospheric boundary layer depth.

    Science.gov (United States)

    Davy, Richard; Esau, Igor

    2016-05-25

    The Earth has warmed in the last century and a large component of that warming has been attributed to increased anthropogenic greenhouse gases. There are also numerous processes that introduce strong, regionalized variations to the overall warming trend. However, the ability of a forcing to change the surface air temperature depends on its spatial and temporal distribution. Here we show that the efficacy of a forcing is determined by the effective heat capacity of the atmosphere, which in cold and dry climates is defined by the depth of the planetary boundary layer. This can vary by an order of magnitude on different temporal and spatial scales, and so we get a strongly amplified temperature response in shallow boundary layers. This must be accounted for to assess the efficacy of a climate forcing, and also implies that multiple climate forcings cannot be linearly combined to determine the temperature response.

  8. Double-diffusive natural convective boundary-layer flow of a nano-fluid past a vertical plate

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, A.V. [Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, Raleigh, NC 27695-7910 (United States); Nield, D.A. [Department of Engineering Science, University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand)

    2011-05-15

    The double-diffusive natural convective boundary-layer flow of a nano-fluid past a vertical plate is studied analytically. The model used for the binary nano-fluid incorporates the effects of Brownian motion and thermophoresis. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. A similarity solution is presented. Numerical calculations were performed in order to obtain correlation formulas giving the reduced Nusselt number as a function of the various relevant parameters. (authors)

  9. Boundary value analysis of parallel plate capacitors%平板电容器的边值分析

    Institute of Scientific and Technical Information of China (English)

    赵琳; 蒋泽

    2004-01-01

    将平板电容器电容的计算作为典型的场边值问题进行处理,从而得到了可适用于对具有任意极板半径与其间隔之比的平板电容器电容的分析求解关系,数值计算结果与有关理论分析的高度一致性,表明了所建立的分析模型的有效性。%By taking the computation of capacitance of a parallel plate capacitor as a boundary value problem.a formula for the computation with any ratio of the plate separation to the radius of the plate is presented.The model shows effectiveness by the good agreement between the analytical and the numerical results.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wissink, Jan G. [School of Engineering and Design, Howell Building, Brunel University, Uxbridge UB8 3PH (United Kingdom)], E-mail: jan.wissink@brunel.ac.uk; Rodi, Wolfgang [Institute for Hydromechanics, University of Karlsruhe, Kaiserstr. 12, D-76128 Karlsruhe (Germany)

    2009-10-15

    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.

  11. 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.

  12. Pull-in voltage of microswitch rough plates in the presence of electromagnetic and acoustic Casimir forces

    NARCIS (Netherlands)

    Palasantzas, George

    2007-01-01

    In this work, we investigate the combined influence of electromagnetic and acoustic Casimir forces on the pull-in voltage of microswitches with self-affine rough plates. It is shown that for plate separations within the micron range the acoustic term arising from pressure fluctuations can influence

  13. Pull-in voltage of microswitch rough plates in the presence of electromagnetic and acoustic Casimir forces

    NARCIS (Netherlands)

    Palasantzas, George

    2007-01-01

    In this work, we investigate the combined influence of electromagnetic and acoustic Casimir forces on the pull-in voltage of microswitches with self-affine rough plates. It is shown that for plate separations within the micron range the acoustic term arising from pressure fluctuations can influence

  14. Long-lived force patterns and deformation waves at repulsive epithelial boundaries

    Science.gov (United States)

    Rodríguez-Franco, Pilar; Brugués, Agustí; Marín-Llauradó, Ariadna; Conte, Vito; Solanas, Guiomar; Batlle, Eduard; Fredberg, Jeffrey J.; Roca-Cusachs, Pere; Sunyer, Raimon; Trepat, Xavier

    2017-10-01

    For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell-matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary.

  15. A simple and robust boundary treatment for the forced Korteweg-de Vries equation

    Science.gov (United States)

    Lee, Hyun Geun; Kim, Junseok

    2014-07-01

    In this paper, we propose a simple and robust numerical method for the forced Korteweg-de Vries (fKdV) equation which models free surface waves of an incompressible and inviscid fluid flow over a bump. The fKdV equation is defined in an infinite domain. However, to solve the equation numerically we must truncate the infinite domain to a bounded domain by introducing an artificial boundary and imposing boundary conditions there. Due to unsuitable artificial boundary conditions, most wave propagation problems have numerical difficulties (e.g., the truncated computational domain must be large enough or the numerical simulation must be terminated before the wave approaches the artificial boundary for the quality of the numerical solution). To solve this boundary problem, we develop an absorbing non-reflecting boundary treatment which uses outward wave velocity. The basic idea of the proposing algorithm is that we first calculate an outward wave velocity from the solutions at the previous and present time steps and then we obtain a solution at the next time step on the artificial boundary by moving the solution at the present time step with the velocity. And then we update solutions at the next time step inside the domain using the calculated solution on the artificial boundary. Numerical experiments with various initial conditions for the KdV and fKdV equations are presented to illustrate the accuracy and efficiency of our method.

  16. Study of a prototypical convective boundary layer observed during BLLAST: contributions by large-scale forcings

    Directory of Open Access Journals (Sweden)

    H. Pietersen

    2014-07-01

    Full Text Available We study the disturbances of CBL dynamics due to large-scale atmospheric contributions for a representative day observed during the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST campaign. We first reproduce the observed boundary-layer dynamics by combining the Dutch Atmospheric Large-Eddy Simulation (DALES model with a mixed-layer theory based model. We find that by only taking surface and entrainment fluxes into account, the boundary-layer height is overestimated by 70%. If we constrain our numerical experiments with the BLLAST comprehensive data set, we are able to quantify the contributions of advection of heat and moisture, and subsidence. We find that subsidence has a clear diurnal pattern. Supported by the presence of a nearby mountain range, this pattern suggests that not only synoptic scales exert their influence on the boundary layer, but also mesoscale circulations. Finally, we study whether the vertical and temporal evolution of turbulent variables are influenced by these large-scale forcings. Our model results show good correspondence of the vertical structure of turbulent variables with observations. Our findings further indicate that when large-scale advection and subsidence are applied, the values for turbulent kinetic are lower than without these large-scale forcings. We conclude that the prototypical CBL can still be used as a valid representation of the boundary-layer dynamics near regions characterized by complex topography and small-scale surface heterogeneity, provided that surface- and large-scale forcings are well characterized.

  17. 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.

  18. Analytical solution of lipid membrane morphology subjected to boundary forces on the edges of rectangular membranes

    Science.gov (United States)

    Belay, T.; Kim, C. I.; Schiavone, P.

    2016-03-01

    We develop a complete analytical solution predicting the deformation of rectangular lipid membranes resulting from boundary forces acting on the perimeter of the membrane. The shape equation describing the equilibrium state of a lipid membrane is taken from the classical Helfrich model. A linearized version of the shape equation describing membrane morphology (within the Monge representation) is obtained via a limit of superposed incremental deformations. We obtain a complete analytical solution by reducing the corresponding problem to a single partial differential equation and by using Fourier series representations for various types of boundary forces. The solution obtained predicts smooth morphological transition over the domain of interest. Finally, we note that the methods used in our analysis are not restricted to the particular type of boundary conditions considered here and can accommodate a wide class of practical and important edge conditions.

  19. The interpretation of crustal dynamics data in terms of plate motions and regional deformation near plate boundaries

    Science.gov (United States)

    Solomon, Sean C.

    During our participation in the NASA Crustal Dynamics Project under NASA contract NAS-27339 and grant NAG5-814 for the period 1982-1991, we published or submitted for publication 30 research papers and 52 abstracts of presentations at scientific meetings. In addition, five M.I.T. Ph.D. students (Eric Bergman, Steven Bratt, Dan Davis, Jeanne Sauber, Anne Sheehan) were supported wholly or in part by this project during their thesis research. Highlights of our research progress during this period include the following: application of geodetic data to determine rates of strain in the Mojave block and in central California and to clarify the relation of such strain to the San Andreas fault and Pacific-North American plate motions; application of geodetic data to infer post seismic deformation associated with large earthquakes in the Imperial Valley, Hebgen Lake, Argentina, and Chile; determination of the state of stress in oceanic lithosphere from a systematic study of the centroid depths and source mechanisms of oceanic intraplate earthquakes; development of models for the state of stress in young oceanic regions arising from the differential cooling of the lithosphere; determination of the depth extent and rupture characteristics of oceanic transform earthquakes; improved determination of earthquake slip vectors in the Gulf of California, an important data set for the estimation of Pacific-North American plate motions; development of models for the state of stress and mechanics of fold-and-thrust belts and accretionary wedges; development of procedures to invert geoid height, residual bathymetry, and differential body wave travel time residuals for lateral variations in the characteristic temperature and bulk composition of the oceanic upper mantle; and initial GPS measurements of crustal deformation associated with the Imperial-Cerro Prieto fault system in southern California and northern Mexico. Full descriptions of the research conducted on these topics may be

  20. Radiation and Viscous Dissipation Effects on Laminar Boundary Layer Flow Nanofluid over a Vertical Plate with a Convective Surface Boundary Condition with Suction

    Directory of Open Access Journals (Sweden)

    K. Gangadhar

    2016-01-01

    Full Text Available The problem of laminar radiation and viscous dissipation effects on laminar boundary layer flow over a vertical plate with a convective surface boundary condition is studied using different types of nanoparticles. The general governing partial differential equations are transformed into a set of two nonlinear ordinary differential equations using unique similarity transformation. Numerical solutions of the similarity equations are obtained using the Nachtsheim-Swigert Shooting iteration technique along with the fourth order Runga Kutta method. Two different types of nanoparticles copper water nanofluid and alumina water nanofluid are studied. The effects of radiation and viscous dissipation on the heat transfer characteristics are discussed in detail. It is observed that as Radiation parameter increases, temperature decreases for copper water and alumina water nanofluid and the heat transfer coefficient of nanofluids increases with the increase of convective heat transfer parameter for copper water and alumina water nanofluids.

  1. DUAL RECIPROCITY HYBRID BOUNDARY NODE METHOD FOR THREE-DIMENSIONAL ELASTICITY WITH BODY FORCE

    Institute of Scientific and Technical Information of China (English)

    Fei Yan; Yuanhan Wang; Yu Miao; Fei Tan

    2008-01-01

    Combining Dual Reciprocity Method (DRM) with Hybrid Bòundary Node Method(HBNM),the Dual Reciprocity Hybrid Boundary Node Method (DRHBNM) is developed for three-dimensional linear elasticity problems with body force.This method can be used to solve the elasticity problems with body force without domain integral,which is inevitable by HBNM.To demonstrate the versatility and the fast convergence of this method,some numerical examples of 3-D elasticity problems with body forces are examined.The computational results show that the present method is effective and can be widely applied in solving practical engineering problems.

  2. Earthquake prediction on boundaries of the Arabian Plate: premonitory chains of small earthquakes

    Science.gov (United States)

    Yaniv, M.; Agnon, A.; Shebalin, P.

    2009-12-01

    Target, i.e. all events are aftershocks; potential foreshocks are not a part of the chain. The algorithm is catalog sensitive. The Nueiba and Paphos events were recognized by the original RTP system (Shebalin et al., 2004), and were used for the calibration of the system before the prediction-in-advance phase was initiated. The detection of the smaller 1993 Red sea event (M6.1) is unique to the modified algorithm. These events, strongest in the catalog, were preceded by “foreshocks” within their chains as shown in the table. We see indications that different types of plate boundaries have different patterns of microseismicity: transform faults may have a clearer premonitory signal than normal faults. The three chains

  3. Slow Growth Formulation for DNS of Chemically Reacting Temporal Boundary Layers with Forcing

    Science.gov (United States)

    Topalian, Victor; Oliver, Todd; Moser, Robert

    2012-11-01

    Extensions to a previously developed formulation for DNS of temporally evolving boundary layers are presented. The original formulation, which allows characterization of turbulence in a temporal boundary layer at a chosen stage of the development, uses a multiscale approach where the fast evolution of the turbulent fluctuations is simulated directly while the slow evolution of averaged quantities is modeled. Specifically, the source terms from slow evolution are modeled assuming self-similarity in the evolution of mean and RMS quantities. Here, the formulation is extended to enable DNS of chemically reacting boundary layers with forcing. These extensions are used to obtain DNS data for conditions similar to those observed in the boundary layer during athmospheric reentry of the NASA CEV. Data from this simulation will be used to inform turbulence model calibration and UQ. This work is supported by the Department of Energy [National Nuclear Security Administration] under Award Number [DE-FC52-08NA28615].

  4. Forced Convective Air Cooling from Electronic Component Arrays in a Parallel Plate Channel

    Institute of Scientific and Technical Information of China (English)

    D.Y.Cai; Y.P.Gan; 等

    1994-01-01

    This paper discusses air forced convection heat transfer from inline protruding elements arranged in eight rows.The streamwise and spanwise spacings between elements were varied using a splitter plate that can be positioned at three different modular configurations.A set of empirical formulas was presented to correlate the experimental data for the design of air cooling systems.Arrays of componets with one odd-size module have been tested also.Experimental results show that blocks near the entrance and behind the odd-size module have improved performance compared with uniform arrangements.Accordingly,temperature sensitive components are suggested to be arranged in these locations.

  5. The forced vibrations of three-layer orthotropic plate at incomplete contact between bottom layers

    Directory of Open Access Journals (Sweden)

    Aghalovyan L. A.

    2007-09-01

    Full Text Available The three-dimensional dynamic problem of the elasticity theory on forced vibration of orthotropic plate at incomplete contact between bottom layers and at full contact between the top layers is solved by the asymptotic method. The bottom obverse surface is subject to external dynamic influences, and top - is rigidly fixed. The common asymptotic solution of the problem is found. The closed solution for particular type of problems is found. It is known, that constant tangential displacements acting to the third layer do not influence in stress-strain state of the first and second layer. The resonance arising conditions are established.

  6. Paleomagnetic constraints on Cenozoic deformation along the northwest margin of the Pacific-Australian plate boundary zone through New Zealand

    Science.gov (United States)

    Turner, Gillian M.; Michalk, Daniel M.; Little, Timothy A.

    2012-02-01

    New Zealand straddles the boundary between the Australian and Pacific plates, a zone of oblique continental convergence and transform motion. The actively deforming region offers a unique opportunity to study the dynamics of deformation, including vertical-axis rotation of rigid blocks within a transcurrent plate boundary zone. We present and interpret paleomagnetic data from three new and three previously published sites from the NW part of the South Island (NW Nelson region), where sedimentary strata dated between 36 and 10 Ma overlie the crystalline Paleozoic basement assemblages of the Gondwana margin. Compared with reference directions from the Australian apparent polar wander path, none of the results provide evidence of post-Eocene vertical-axis rotation. This suggests that for the past 36 Myr NW Nelson has remained a strong, coherent block that has moved as a contiguous part of the Australian plate. This is in marked contrast to the strongly rotated nature of more outboard accreted terranes to the east. For example, the Hikurangi Margin in the North Island (NW of the Alpine Fault) and the Marlborough region in the NE of the South Island (SE of the Alpine Fault), have both undergone diverse clockwise rotations of up to 140° since the early Paleogene. The NW tip of the South Island seems to have acted as a rigid backstop relative to these more complex oroclinal deformations. We infer that, because of its relatively stiff bulk rheology, it has not been drawn into the distributed plate boundary rotational deformation associated with the New Zealand Orocline.

  7. The EarthScope Plate Boundary Observatory Alaska Region: Highlights from the 2012 Summer Field Season

    Science.gov (United States)

    Enders, M.; Bierma, R. M.; Boyce, E. S.; Willoughby, H.; Fend, M.; Feaux, K.

    2012-12-01

    UNAVCO has now completed its fourth year of operation and maintenance of the 138 continuous GPS stations, 12 tiltmeters and 31 data communications relays that comprise the Alaska region of the EarthScope Plate Boundary Observatory (PBO). The successful operation of the autonomous GPS and tiltmeter network in Alaska continues to be a challenge, because of logistics, weather, and other difficulties related to working in Alaska. PBO engineers continue to work on network enhancements to make the stations more robust, while improving overall data quality and station uptime to better serve the EarthScope science community. In the summer of 2012, PBO engineers completed maintenance activities in Alaska, which resulted in a 95% operational status for the Alaska network within PBO. PBO engineers completed a total of 87 maintenance visits in the summer of FY2012, including 62 routine maintenance and 25 unscheduled maintenance visits to GPS and data communications stations. We present a number of highlights and accomplishments from the PBO 2012 summer field season in Alaska, for example the deployment of a newly designed methanol fuel cell at AV35, a critical station that serves as the main repeater for the real time network on Unimak Island. In addition, PBO engineers also completed the installation of three Inmarsat BGAN terminals for data telemetry following successful testing at AC60 Shemya. Lastly, PBO engineers completed scheduled battery replacements at most of the PBO stations on Unimak Island, in collaboration with the USGS/Alaska Volcano Observatory. In addition to routine maintenance and planned station improvements to sites in Alaska, numerous critical repairs were made at stations on Unimak Island and elsewhere to ensure that the PBO network continues to function well and continues to meet the requirements stipulated by the NSF. We also present some of the station failures unique to Alaska, which we encountered during the course of the 2012 field season, as well

  8. The Earthscope Plate Boundary Observatory Alaska Region an Overview of Network Operation, Maintenance and Improvement

    Science.gov (United States)

    Enders, M.; Boyce, E. S.; Bierma, R.; Walker, K.; Feaux, K.

    2011-12-01

    UNAVCO has now completed its third year of operation of the 138 continuous GPS stations, 12 tiltmeters and 31 communications relays that comprise the Alaska Region of the Earthscope Plate Boundary Observatory. Working in Alaska has been challenging due to the extreme environmental conditions encountered and logistics difficulties. Despite these challenges we have been able to complete each summer field season with network operation at 95% or better. Throughout the last three years we have analyzed both our successes and failures to improve the quality of our network and better serve the scientific community. Additionally, we continue to evaluate and deploy new technologies to improve station reliability and add to the data set available from our stations. 2011 was a busy year for the Alaska engineering team and some highlights from last year's maintenance season include the following. This spring we completed testing and deployment of the first Inmarsat BGAN satellite terminal for data telemetry at AC60 Shemya Island. Shemya Island is at the far western end of the Aleutian Islands and is one of the most remote and difficult to access stations in the PBO AK network. Until the installation of the BGAN, this station was offline with no data telemetry for almost one year. Since the installation of the BGAN in early April 2011 dataflow has been uninterrupted. This year we also completed the first deployments of Stardot NetCamSC webcams in the PBO Network. Currently, these are installed and operational at six GPS stations in Alaska, with plans to install several more next season in Alaska. Images from these cameras can be found at the station homepages linked to from the UNAVCO website. In addition to the hard work put in by PBO engineers this year, it is important that we recognize the contributions of our partners. In particular the Alaska Volcano Observatory, the Alaska Earthquake Information Center and others who have provided us with valuable engineering assistance

  9. The Plate Boundary Observatory (PBO) Network in the PNW region of the United States

    Science.gov (United States)

    Hafner, K.; Austin, K.; Feaux, K.; Jackson, M.; Fengler, K.; Doelger, S.

    2007-05-01

    The Pacific Northwest Region (PNW) of the United States contains a variety of geologic regions and tectonic problems. These include the Cascadia Subduction Zone, Mt. St. Helens and the transition to the Basin and Range province. Since September of 2003, the Plate Boundary Observatory (PBO), which is part of the larger NSF-funded EarthScope project, has been installing a network of continuously operating GPS, strainmeter and tiltmeter instruments. There are currently 78 GPS, 13 strainmeter/borehole seismometers, and 4 tiltmeters operating in the PNW region. The data from this network has already been used to study Episodic Tremor Events (ETS) during September 2005 and January 2007, and renewed activity on Mt. St. Helens that began on September 23, 2004. The goal is have 134 continuously operating GPS stations by the end of September 2008. The locations of the GPS stations were determined by scientific committees. Whenever possible, multiple instruments are deployed at the same location, and share power and communications resources. Examples of this are GPS antennas mounted on top of strainmeter boreholes in the forearc region of western Washington and tiltmeters collecting data through GPS receivers on Mt. St. Helens. In addition, a number of stations provide real time kinematic data to professional surveyors within the region. During the fall of 2006, a 16 GPS and 4 tiltmeter station network was completed on Mt. St. Helens. Results from analysis of both PBO and USGS GPS stations on the mountain, show a radially inward and downward motion, with the maximum vertical offsets high on the mountain and the maximum horizontal offsets located at distances of 5-10km from the crater. Displacements are small over the 2004-present eruption with a maximum of 3cm of inward movement. GPS stations installed high on the mountain experience severe weather and heavy rime accumulations for approximately 6 months of the year. Ice build-up causes distortion of the GPS antenna phase

  10. Evolving seismogenic plate boundary megathrust and mega-splay faults in subduction zone (Invited)

    Science.gov (United States)

    Kimura, G.; Hamahashi, M.; Fukuchi, R.; Yamaguchi, A.; Kameda, J.; Kitamura, Y.; Hashimoto, Y.; Hamada, Y.; Saito, S.; Kawasaki, R.

    2013-12-01

    Understanding the fault mechanism and its relationship to the sesimo-tsunamigenesis is a key of the scientific targets of subduction zone and therefore NantroSEIZE project of IODP and future new drilling project of International Ocean Discovery Program keeps focusing on that. Mega-splay fault branched from plate boundary megathrust in subduction zone is located around the border between outer and inner wedges and is considered to cause great earthquake and tsunami such as 1960 Alaska earthquake, 1944 and 1946 Nankai-Tonankai earthquakes, and 2004 Sumatra earthquakes. Seismic reflection studies for the mega-splay fault in 2D and 3D in the Nankai forearc present the reflector with negative or positive polarities with various amplitudes and suggest complicated petrophysical properties and condition of the fault and its surroundings. The Nankai mega-splay fault at a depth of ~5km is going to be drilled and cored by NantroSEIZE experiments and is expected for great progress of understanding of the fault mechanics. Before drilling the really targeted seismogenic fault, we are conducting many exercises of geophysical and geological observations. The core-log-seismic integrated exercise for the exhumed mega-splay fault by drilling was operated for the Nobeoka thrust in the Shimanto Belt, Kyushu, Japan. The Nobeoka thrust was once buried in the depth >~10km and suffered maximum temperature >~300 dgree C. As the core recovery is ~99%, perfect correlation between the core and logging data is possible. Thickness of the fault zone is >200 m with a ~50 cm thick central fault core dividing the phyllitic hanging wall and the footwall of broken-melange like cataclasite. A-few-meter-thick discrete damage zones with fault cores are recognized by difference in physical properties and visual deformation textures at several horizons in the fault zone. Host rocks for those damaged zones are completely lithified cataclasites with abundant mineral veins, which record the older and deeper

  11. The Plate Boundary Observatory: Current status and plans for the next five years

    Science.gov (United States)

    Mattioli, G. S.; Feaux, K.; Meertens, C. M.; Mencin, D.; Miller, M.

    2013-12-01

    UNAVCO currently operates and maintains the NSF-funded Plate Boundary Observatory (PBO), which is the geodetic facility of EarthScope. PBO was designed and built from 2003 to 2008 with $100M investment from the NSF Major Research Equipment and Facilities Construction (MREFC) Program. UNAVCO operated and maintained PBO under a Cooperative Agreement (CA) with NSF from 2008 to 2013 and will continue PBO O&M for the next five years as part of the new Geodesy Advancing Geosciences and EarthScope (GAGE) Facility. PBO is largest continuous GPS and borehole geophysical network in the Americas, with 1100 continuous Global Positioning System (cGPS) sites, including several with multiple monuments, 79 boreholes, with 75 tensor strainmeters, 78 short-period, 3-component seismometers, and pore pressure sensors at 23 sites. PBO also includes 26 tiltmeters deployed at volcanoes in Alaska, Mt St Helens, and Yellowstone caldera and 6 long-baseline laser strainmeters. Surface meteorological sensors are collocated at 154 GPS sites. UNAVCO provides high-rate (1 Hz), low-latency (streams (RT-GPS) from 382 stations in PBO. UNAVCO has delivered over 62 Tb of geodetic data to the EarthScope community since its PBO's inception in 2004. Over the past year, data return for the cGPS component of PBO is 98%, well above the data return metric of 85% set by the NSF, a result of efforts to upgrade power systems and communications infrastructure. In addition, PBO has set the standard for the design, construction, and operation of other multi-hazard networks across the Americas, including COCONet in the Caribbean region and TLALOCNet in Mexico. Funding to support ongoing PBO O&M has declined from FY2012 CA levels under the new GAGE Facility. The implications for data return and data quality metrics as well as replacement of aging PBO GPS instruments with GNSS-compatible systems are as yet unknown. A process to assess the cost of specific PBO components, data rates, enhanced capabilities, and method

  12. Analytical solutions for thermal forcing vortices in boundary layer and its applications

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-ran; LI Guo-ping

    2007-01-01

    Using the Boussinesq approximation, the vortex in the boundary layer is assumed to be axisymmetrical and thermal-wind balanced system forced by diabatic heating and friction, and is solved as an initial-value problem of linearized vortex equation set in cylindrical coordinates. The impacts of thermal forcing on the flow field structure of vortex are analyzed. It is found that thermal forcing has significant impacts on the flow field structure, and the material representative forms of these impacts are closely related to the radial distribution of heating. The discussion for the analytical solutions for the vortex in the boundary layer can explain some main structures of the vortex over the Tibetan Plateau.

  13. The Influence of Flexibility Coefficient on the Size of Internal Forces and Deformations in Circular Plates on Elastic Medium

    Directory of Open Access Journals (Sweden)

    Şandru Mirela

    2016-09-01

    Full Text Available This paper presents an analytical study which deals with the behavior of the circular plates in bending theory, considering the soil-structure interaction under Winkler's hypothesis. It was intended to illustrate the variation of internal forces and deformations according to the flexibility coefficient of plates considering three models: a fixed solid circular plate subjected to a uniformly distributed load, a fixed solid circular plate acted by a displacement applied on the exterior contour and a solid plate subjected to a temperature gradient. For this study the computation relations were written as a product between a dimensional and a non-dimensional factor, the last one indicating the variation of internal forces and deformations. For each type of action there are presented results obtained using the finite element method to illustrate the differences between this method and the analytical computation.

  14. Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

    NARCIS (Netherlands)

    Sissingh, W.

    2008-01-01

    This paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence

  15. ELECTRICALLY FORCED THICKNESS-SHEAR VIBRATIONS OF QUARTZ PLATE WITH NONLINEAR COUPLING TO EXTENSION

    Institute of Scientific and Technical Information of China (English)

    Rongxing Wu; Jiashi Yang; Jianke Du; Ji Wang

    2008-01-01

    We study electrically forced nonlinear thickness-shear vibrations of a quartz plate resonator with relatively large amplitude. It is shown that thickness-shear is nonlinearly coupled to extension due to the well-known Poynting effect in nonlinear elasticity. This coupling is relatively strong when the resonant frequency of the extensional mode is about twice the resonant frequency of the thickness-shear mode. This happens when the plate length/thickness ratio assumes certain values. With this nonlinear coupling, the thickness-shear motion is no longer sinusoidal. Coupling to extension also affects energy trapping which is related to device mounting. When damping is 0.01, nonlinear coupling causes a frequency shift of the order of 10-e which is not insignificant,and an amplitude change of the order of 10-8. The effects are expected to be stronger under real damping of 10-5 or larger. To avoid nonlinear coupling to extension, certain values of the aspect ratio of the plate should be avoided.

  16. 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.

  17. 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.

  18. Comparison of friction force between corroded and noncorroded titanium nitride plating of metal brackets.

    Science.gov (United States)

    Kao, Chia-Tze; Guo, Jia-Uei; Huang, Tsui-Hsien

    2011-05-01

    Titanium nitride (TiN) plating is a method to prevent metal corrosion and can increase the surface smoothness. The purpose of this study was to evaluate the friction forces between the orthodontic bracket, with or without TiN plating, and stainless steel wire after it was corroded in fluoride-containing solution. In total, 540 metal brackets were divided into a control group and a TiN-coated experimental group. The electrochemical corrosion was performed in artificial saliva with 1.23% acidulated phosphate fluoride (APF) as the electrolytes. Static and kinetic friction were measured by an EZ-test machine (Shimadazu, Tokyo, Japan) with a crosshead speed of 10 mm per minute over a 5-mm stretch of stainless steel archwire. The data were analyzed by using unpaired t test and analysis of variance (ANOVA). Both the control and TiN-coated groups' corrosion potential was higher with 1.23% APF solution than with artificial solution (P TiN-coated brackets groups showed a statistically significant difference (P TiN-coated brackets showed a statistical difference (P TiN-coated metal brackets, with corrosion or without corrosion, cannot reduce the frictional force. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  19. Rolling Force Prediction in Heavy Plate Rolling Based on Uniform Differential Neural Network

    Directory of Open Access Journals (Sweden)

    Fei Zhang

    2016-01-01

    Full Text Available Accurate prediction of the rolling force is critical to assuring the quality of the final product in steel manufacturing. Exit thickness of plate for each pass is calculated from roll gap, mill spring, and predicted roll force. Ideal pass scheduling is dependent on a precise prediction of the roll force in each pass. This paper will introduce a concept that allows obtaining the material model parameters directly from the rolling process on an industrial scale by the uniform differential neural network. On the basis of the characteristics that the uniform distribution can fully characterize the solution space and enhance the diversity of the population, uniformity research on differential evolution operator is made to get improved crossover with uniform distribution. When its original function is transferred with a transfer function, the uniform differential evolution algorithms can quickly solve complex optimization problems. Neural network structure and weights threshold are optimized by uniform differential evolution algorithm, and a uniform differential neural network is formed to improve rolling force prediction accuracy in process control system.

  20. Numerical manifold method for the forced vibration of thin plates during bending.

    Science.gov (United States)

    Jun, Ding; Song, Chen; Wei-Bin, Wen; Shao-Ming, Luo; Xia, Huang

    2014-01-01

    A novel numerical manifold method was derived from the cubic B-spline basis function. The new interpolation function is characterized by high-order coordination at the boundary of a manifold element. The linear elastic-dynamic equation used to solve the bending vibration of thin plates was derived according to the principle of minimum instantaneous potential energy. The method for the initialization of the dynamic equation and its solution process were provided. Moreover, the analysis showed that the calculated stiffness matrix exhibited favorable performance. Numerical results showed that the generalized degrees of freedom were significantly fewer and that the calculation accuracy was higher for the manifold method than for the conventional finite element method.

  1. Numerical Manifold Method for the Forced Vibration of Thin Plates during Bending

    Directory of Open Access Journals (Sweden)

    Ding Jun

    2014-01-01

    Full Text Available A novel numerical manifold method was derived from the cubic B-spline basis function. The new interpolation function is characterized by high-order coordination at the boundary of a manifold element. The linear elastic-dynamic equation used to solve the bending vibration of thin plates was derived according to the principle of minimum instantaneous potential energy. The method for the initialization of the dynamic equation and its solution process were provided. Moreover, the analysis showed that the calculated stiffness matrix exhibited favorable performance. Numerical results showed that the generalized degrees of freedom were significantly fewer and that the calculation accuracy was higher for the manifold method than for the conventional finite element method.

  2. Consideration of SH-wave fundamental modes in piezoelectromagnetic plate: electrically open and magnetically open boundary conditions

    Science.gov (United States)

    Zakharenko, A. A.

    2013-11-01

    This report studies the dispersive wave propagation in the transversely isotropic (6 mm) piezoelectromagnetic (PEM) plate when the mechanical, electrical, and magnetic boundary conditions for both the upper and lower free surfaces of the plate are as follows: the mechanically free, electrically open, and magnetically open surfaces. This study follows some original results obtained in book. The fundamental modes' dispersion relations are graphically shown for the following well-known PEM composite materials: BaTiO3-CoFe2O4 and PZT-5H-Terfenol-D. It is natural that for large values of the nondimensional parameter kd (k is the wave number and d is the plate half-thickness), the velocities of both the fundamental modes approach the surface shear-horizontal wave called the piezomagnetic exchange surface Melkumyan wave. It is well known that plate waves are usually utilized in the nondestructive testing and evaluation, for instance, in the airspace industry. Also, PEM materials are used as smart ones in various technical devices such as dispersive wave delay lines, (biochemi)sensors, lab-on-a-chip, etc.

  3. Boundary layer flow and heat transfer on a moving plate in a copper-water nanofluid using Buongiorno model

    Science.gov (United States)

    Bakar, Nor Ashikin Abu; Bachok, Norfifah; Arifin, Norihan Md.

    2016-06-01

    The study of the steady two dimensional boundary layer flow of a copper (Cu)-water nanofluid on a moving plate is investigated. The assumption is the plate moves in the same or opposite direction to the free stream. The nonlinear partial differential equations are transformed into nonlinear ordinary differential equations using a similarity variables,then a shooting technique is used to solved it numerically. The numerical results for skin friction coefficient, the local Nusselt number, the local Sherwood number as well as the velocity, temperature and concentration profiles are obtained. The effect of nanoparticle volume fraction, Brownian motion and thermophoresis parameters on heat transfer are examined. The results show that the local Nusselt number and the local Sherwood number increase with increasing in the Brownian motion parameter Nb and thermophoresis parameter Nt.

  4. Disruption of Esrom and Ryk identifies the roof plate boundary as an intermediate target for commissure formation.

    Science.gov (United States)

    Hendricks, Michael; Mathuru, Ajay Sriram; Wang, Hui; Silander, Olin; Kee, Michelle Zhi Ling; Jesuthasan, Suresh

    2008-02-01

    Growth cones are guided to their final destination by intermediate targets. Here, we identify intermediate targets and signaling components acting on zebrafish habenula commissural axons. Live imaging establishes that axons pause at the medial habenula before and after crossing the roof plate. esrom mutants axons fail to advance beyond the ipsilateral medial habenula. Tsc2 function is reduced in mutant axons, indicating cell autonomous defects in signaling. Consistent with signaling properties changing outside the roof plate, EphB is surface localized on axon segments within a zone demarcated by the medial habenula. wnt4a is expressed in the medial habenula and morpholino knockdown causes loss of the commissure. Electroporation of truncated Ryk causes axons to reenter the midline after reaching the contralateral habenula. These data identify Esrom as a mediator of growth cone navigation at an intermediate target and underscore the importance of midline boundaries as signaling centers for commissure formation.

  5. 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

  6. EarthScope: Cyberinfrastructure to access Plate Boundary Observatory data products and services

    Science.gov (United States)

    Meertens, C. M.; Mattioli, G. S.; Miller, M.; Boler, F. M.; Crosby, C. J.; Mencin, D.; Phillips, D. A.; Snett, L.

    2013-12-01

    The wealth of data from geodetic observing systems, especially the Plate Boundary Observatory (PBO), presents major data management challenges. The challenges are driven by ingenious new uses of Global Positioning System (GPS) data, demands for higher-rate, lower latency data, the need for continued access and long term preservation of archival data, the expansion of data users into other science, engineering and commercial arenas, and the growth of enhanced products that expand the utility of the data. To meet these challenges, UNAVCO has established a comprehensive suite of data services encompassing sensor network data operations, data product generation (through the activities of partners at Massachusetts Institute of Technology, Central Washington University, New Mexico Institute of Mining and Technology, and the University of California, San Diego - UCSD), data management, access and archiving, and advanced cyberinfrastructure. PBO sensor systems include 1,100 continuously operating GPS stations, 79 borehole geophysical sites (with a combination of strainmeters, tiltmeters, seismometers, pore pressure gauges, and meteorological sensors), and 6 long baseline strainmeters. Imaging data acquired for EarthScope include large volumes of satellite synthetic aperture radar (SAR) and airborne LiDAR data. Core data products such as daily GPS position time series and derived crustal motion velocities have been augmented with real-time data streams and positions calculated every second from 367 PBO stations. Higher rate (5 Hz) data files are available for applications such as GPS seismology. Efforts are underway with UCSD to integrate GPS and accelerometers at a subset of PBO sites to increase the reliability and capability of the observations. These observations have utility for research and hazards mitigation. Ingenious methods of GPS data analysis, developed by the University of Colorado and the University Corporation for Atmospheric Research, measure snow depth

  7. What can we Learn From Small Non-Recoverable Strains at Plate Boundaries?

    Science.gov (United States)

    Lewis, J. C.; Pluhar, C. J.

    2003-12-01

    Background seismicity carries often overlooked information about how the crust responds to plate motions. Integrating focal mechanisms for background seismicity with (1) geologic observations, and (2) geodetic constraints, is critical to establishing a better understanding of both the rock record and contemporary deformation. Treating the crust as a micropolar continuum it is possible to constrain not only the orientations and relative magnitudes of the principal strains but also the vorticity of crustal blocks with respect to the large-scale continuum. We show the utility of this approach with examples from the Cascadia margin and the Coso Range (within the Eastern California shear zone). In the upper crust of the Cascadia margin, seismogenic strain appears to be dominated by accommodation of motion of the Oregon forearc block. This suggests that the shallow crust is responding to long-term motion of the Oregon forearc rather than the interseismic locking of the subduction megathrust. In the area west of Mt. Rainier, this response is marked by non-zero relative vorticity in a regime of N-S shortening and crustal thickening. To date, geologic studies necessary to evaluate the significance of this vorticity have not been completed. In contrast within the Coso Range of California, seismogenic strain at Wild Horse Mesa indicates a component of relative vorticity that is broadly consistent with paleomagnetically constrained finite rotations of the ca. 3 Ma lava flows that compose the mesa. This area is centered at a right-releasing step in the Eastern California shear zone and thus is experiencing active transtension. Stratigraphic constraints have been used to suggest that significant dextral shearing in this region initiated ca. 3.5-2 Ma. The seismogenic response to transtension is depth-dependent plane strain with crustal thinning above 5 km and horizontal dextral shearing from 5-8 km. Both structural levels indicate subhorizontal E-W maximum stretching. Relative

  8. Secular and annual hydrologic effects from the Plate Boundary Observatory GPS network

    Science.gov (United States)

    Meertens, C. M.; Wahr, J. M.; Borsa, A. A.; Jackson, M. E.; Herring, T.

    2009-12-01

    The Plate Boundary Observatory (PBO) GPS network is providing accurate and spatially coherent vertical signals that can be interpreted in terms of hydrological loading and poroelastic effects from both natural and anthropogenic changes in water storage. Data used for this analysis are the precise coordinate time series produced on a daily basis by PBO Analysis Centers at New Mexico Institute of Mining and Technology and at Central Washington University and combined by the Analysis Center Coordinator at the Massachusetts Institute of Technology. These products, as well as derived velocity solutions, are made freely available from the UNAVCO Data Center in Boulder. Analysis of secular trends and annual variations in the time series was made using the analysis software of Langbein, 2008. Spatial variations in the amplitude and phase of the annual vertical component of motion allow for identification of anthropogenic effects due to water pumping, irrigation, and reservoir lake variations, and of outliers due to instrumental or other local site effects. Vertical annual signals of 8-10 mm peak-to-peak amplitude are evident at stations in the mountains of northern and central California and the Pacific Northwest. The peak annual uplift is in October and is correlated to hydrological loading effects. Mountainous areas appear to be responding elastically to the load of the water contained in surface soil, fractures, and snow. Vertical signals are highest when the water load is at a minimum. The vertical elastic hydrologic loading signal was modeled using the 0.25 degree community NOAH land-surface model (LSM) and generally fits the observed GPS signal. Addition comparisons will be made using the Mosaic LSM and the NOAA “Leaky Bucket” hydrologic model. In contrast to mountain stations that are installed principally in bedrock, stations in the valleys of California are installed in sediments. Observations from these stations show greater spatial variability ranging from

  9. The EarthScope Plate Boundary Observatory Distributed Data Management System

    Science.gov (United States)

    Anderson, G.; Eakins, J.; Hodgkinson, K.; Matykiewicz, J.; Beldyk, M.; Blackman, B.; Boler, F.; Henderson, B.; Hoyt, B.; Lee, E.; Persson, E.; Smith, J.; Torrez, D.; Wright, J.; Jackson, M.; Meertens, C.

    2007-05-01

    EarthScope is an ambitious multi-year project funded by the United States National Science Foundation to explore the structure and dynamics of the North American continent using a wide range of geophysical methods. The Plate Boundary Observatory (PBO), being built by UNAVCO, is the geodetic component of EarthScope, and will comprise 880 continuous GPS stations, 103 borehole strainmeter stations, 28 tiltmeters, and five laser strainmeters; in addition, PBO will manage data for 209 existing GPS stations and 11 GPS stations installed by the USArray segment of EarthScope. As of February 2007, 561 of these stations have been installed. PBO data flow is managed from the PBO Boulder Network Operations Center (NOC), located at UNAVCO Headquarters. Automated systems at the NOC retrieve data from our stations at least daily, monitor the status of the network and alert operators to problems, and pass data on for analysis, archiving, and distribution. Real-time network status can be found at http:pboweb.unavco.org/soh_map. PBO's analysis centers generate high-quality derived data products from PBO raw data. Two centers, at Central Washington University and the New Mexico Institute of Mining and Technology, process raw GPS data to produce initial PBO GPS products including network solutions and station position time series, andthese products are combined by the Analysis Center Coordinator at MIT to produce the official PBO GPS products. Two analysis centers, at UNAVCO's Socorro office and the University of California, San Diego, process data from the PBO borehole and laser strainmeter networks and produce cleaned time series of shear, areal, and linear strain, Earth tides, pore fluid pressure, and other parameters. The UNAVCO Facility archives and distributes all PBO GPS data products and runs a secondary archive offsite; to date, these centers hold more than 2.5 TB of PBO products. The IRIS Data Management Center and Northern California Earthquake Data Center archive and

  10. Prediction of metallic nano-optical trapping forces by finite element-boundary integral method.

    Science.gov (United States)

    Pan, Xiao-Min; Xu, Kai-Jiang; Yang, Ming-Lin; Sheng, Xin-Qing

    2015-03-01

    The hybrid of finite element and boundary integral (FE-BI) method is employed to predict nano-optical trapping forces of arbitrarily shaped metallic nanostructures. A preconditioning strategy is proposed to improve the convergence of the iterative solution. Skeletonization is employed to speed up the design and optimization where iteration has to be repeated for each beam configuration. The radiation pressure force (RPF) is computed by vector flux of the Maxwell's stress tensor. Numerical simulations are performed to validate the developed method in analyzing the plasmonic effects as well as the optical trapping forces. It is shown that the proposed method is capable of predicting the trapping forces of complex metallic nanostructures accurately and efficiently.

  11. Crustal structure and seismicity distribution adjacent to the Pacific and North American plate boundary in southern California

    OpenAIRE

    Hauksson, Egill

    2000-01-01

    New three-dimensional (3-D) V_P and V_P/V_S models are determined for southern California using P and S-P travel times from local earthquakes and controlled sources. These models confirm existing tectonic interpretations and provide new insights into the configuration of geological structures at the Pacific-North America plate boundary. The models extend from the U.S.-Mexico border in the south to the southernmost Coast Ranges and Sierra Nevada in the north and have a 15-km horizontal grid sp...

  12. The reliability of the improved eN method for the transition prediction of boundary layers on a flat plate

    Institute of Scientific and Technical Information of China (English)

    SU CaiHong

    2012-01-01

    The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1%-2% of the free stream velocity,while in the conventional eN method,the N factor is an empirical factor.In this paper the reliability of this key assumption in the improved eN method is checked by results of transition prediction by using the Parabolized Stability Equations (PSE).Transition locations of an incompressible boundary layer and a hypersonic boundary layer at Mach number 6 on a flat plate are predicted by both the improved eN method and the PSE method.Results from both methods agree fairly well with each other,implying that the transition criterion proposed in the improved eN method is reliable.

  13. Accurate computation of surface stresses and forces with immersed boundary methods

    CERN Document Server

    Goza, Andres; Morley, Benjamin; Colonius, Tim

    2016-01-01

    Many immersed boundary methods solve for surface stresses that impose the velocity boundary conditions on an immersed body. These surface stresses may contain spurious oscillations that make them ill-suited for representing the physical surface stresses on the body. Moreover, these inaccurate stresses often lead to unphysical oscillations in the history of integrated surface forces such as the coefficient of lift. While the errors in the surface stresses and forces do not necessarily affect the convergence of the velocity field, it is desirable, especially in fluid-structure interaction problems, to obtain smooth and convergent stress distributions on the surface. To this end, we show that the equation for the surface stresses is an integral equation of the first kind whose ill-posedness is the source of spurious oscillations in the stresses. We also demonstrate that for sufficiently smooth delta functions, the oscillations may be filtered out to obtain physically accurate surface stresses. The filtering is a...

  14. PLATE

    DEFF Research Database (Denmark)

    Kling, Joyce; Hjulmand, Lise-Lotte

    2008-01-01

    ’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through......Copenhagen Business School (CBS) finds itself needing to address the issue of English-medium instruction for its increasing number of foreign exchange and full degree students. With internationalisation as a main pillar of the institution’s agenda, there are concerns whether the teaching faculty...... the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature...

  15. PLATE

    DEFF Research Database (Denmark)

    Kling, Joyce; Hjulmand, Lise-Lotte

    2008-01-01

    Copenhagen Business School (CBS) finds itself needing to address the issue of English-medium instruction for its increasing number of foreign exchange and full degree students. With internationalisation as a main pillar of the institution’s agenda, there are concerns whether the teaching faculty......’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through...... the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature...

  16. Analysis on Forced Vibration of Thin-Wall Cylindrical Shell with Nonlinear Boundary Condition

    Directory of Open Access Journals (Sweden)

    Qiansheng Tang

    2016-01-01

    Full Text Available Forced vibration of thin-wall cylindrical shell under nonlinear boundary condition was discussed in this paper. The nonlinear boundary was modeled as supported clearance in one end of shell and the restraint was assumed as linearly elastic in the radial direction. Based on Sanders’ shell theory, Lagrange equation was utilized to derive the nonlinear governing equations of cylindrical shell. The displacements in three directions were represented by beam functions and trigonometric functions. In the study of nonlinear dynamic responses of thin-wall cylindrical shell with supported clearance under external loads, the Newmark method is used to obtain time history, frequency spectrum plot, phase portraits, Poincare section, bifurcation diagrams, and three-dimensional spectrum plot with different parameters. The effects of external loads, supported clearance, and support stiffness on nonlinear dynamics behaviors of cylindrical shell with nonlinear boundary condition were discussed.

  17. Critical Casimir force scaling functions of the two-dimensional Ising model for various boundary conditions

    CERN Document Server

    Hobrecht, Hendrik

    2016-01-01

    We present a systematic method to calculate the scaling functions for the critical Casimir force and the according potential of the two-dimensional Ising model with various boundary conditions. Therefore we start with the dimer representation of the corresponding partition function $Z$ on an $L\\times M$ square lattice, wrapped around a torus with aspect ratio $\\rho=L/M$. By assuming periodic boundary conditions and translational invariance in at least one direction, we systematically reduce the problem to a $2\\times2$ transfer matrix representation. For the torus we first reproduce the results by Kaufman and then give a detailed calculation of the scaling functions. Afterwards we present the calculation for the cylinder with open boundary conditions. All scaling functions are given in form of combinations of infinite products and integrals. Our results reproduce the known scaling functions in the limit of thin films $\\rho\\to 0$. Additionally, for the cylinder at criticality our result confirms the predictions...

  18. Iterative methods for obtaining solvation structures on a solid plate: The methods for Surface Force Apparatus and Atomic Force Microscopy in Liquids

    CERN Document Server

    Amano, Ken-ich

    2013-01-01

    We propose iterative methods for obtaining solvation structures on a solid plate which use force distributions measured by surface force apparatus (SFA) and atomic force microscopy (AFM) as input data. Two model systems are considered here. In the model system for SFA, the same two solid plates are immersed in a solvent, and a probe tip and a solid plate are immersed in a solvent in the model system for AFM. Advantages of the iterative methods are as follows: The iterative method for SFA can obtain the solvation structure, for example, in a Lennard-Jones liquid; The iterative method for AFM can obtain the solvation structure without an input datum of solvation structure around the probe tip.

  19. On symmetric equilibrium of an isothermal gas with a free boundary and a body force

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The equation of symmetric equilibrium of an isothermal gas with an unknown boundary in the field of a body force is considered. Conditions for solvability and insolvability of the problem as well as for uniqueness and nonuniqueness of solutions are presented. Examples of finite, countable, or continual sets of solutions are constructed including equipotential ones. Static stability of solutions is analyzed too.

  20. Logarithmic interaction under periodic boundary conditions: closed form formulas for energy and forces

    Science.gov (United States)

    Tyagi, Sandeep

    A method is given to obtain closed form formulas for the energy and forces for an aggregate of charges interacting via a logarithmic interaction under periodic boundary conditions. The work done here is a generalization of Glasser's results [J. Math. Phys., 15, 188 (1974)] and is obtained with a different and simpler method than that by Stremler [J. Math. Phys., 45, 3584 (2004)]. The simplicity of the formulas derived here makes them extremely convenient in a computer simulation.

  1. Logarithmic interaction under periodic boundary conditions: Closed form formulas for energy and forces

    OpenAIRE

    2005-01-01

    A method is given to obtain closed form formulas for the energy and forces for an aggregate of charges interacting via a logarithmic interaction under periodic boundary conditions. The work done here is a generalization of Glasser's results [M. L. Glasser, J. Math. Phys. 15, 188 (1974)] and is obtained with a different and simpler method than that by Stremler [M. A. Stremler, J. Math. Phys. 45, 3584 (2004)]. The simplicity of the formulas derived here makes them extremely convenient in a comp...

  2. Guest editor - Material exchanges at marine boundaries and surface ocean processes: Forcings and feedbacks

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    -1 Special section on: Material exchanges at marine boundaries and surface ocean processes: Forcings and feedbacks Preface Exchanges across marine interfaces are important in global material cycles and in the modification of atmospheric composition. Climate... and feedbacks was held during the 2nd Annual Meeting of the Asia?Oceania Geosciences Society (AOGS) in Singapore during 20?24 June 2005. The following Special section contains some of the papers presented at that session. The first article by Sarma addresses...

  3. DSMC simulations of leading edge flat-plate boundary layer flows at high Mach number

    Science.gov (United States)

    Pradhan, Sahadev, , Dr.

    2017-01-01

    The flow over a 2D leading-edge flat plate is studied at Mach number Ma = (Uinf /√{kBTinf / m }) in the range Boltzmann constant. The variation of streamwise velocity, temperature, number-density, and mean free path along the wall normal direction away from the plate surface is studied. The qualitative nature of the streamwise velocity at high Mach number is similar to those in the incompressible limit (parabolic profile). However, there are important differences. The amplitudes of the streamwise velocity increase as the Mach number increases and turned into a more flatter profile near the wall. There is significant velocity and temperature slip at the surface of the plate, and the slip increases as the Mach number is increased. It is interesting to note that for the highest Mach numbers considered here, the streamwise velocity at the wall exceeds the sound speed, and the flow is supersonic throughout the flow domain.

  4. Influence of conducting plate boundary conditions on the transverse envelope equations describing intense ion beam transport

    Directory of Open Access Journals (Sweden)

    Steven M. Lund

    2004-06-01

    Full Text Available In typical diagnostic applications, intense ion beams are intercepted by a conducting plate associated with devices used to measure beam phase-space projections. This results in the transverse space-charge field near the plate being shorted out, rendering simple envelope models with constant space-charge strength inaccurate. Here we develop corrected envelope models based on analytical calculations to account for this effect on the space-charge term of the envelope equations, thereby removing a systematic source of error in the equations and enabling more accurate comparisons with experiment. For common intense beam parameters, we find that the envelope correction occurs primarily in the envelope angles near the plate and that the effect can be large enough to degrade precision beam matching in periodic transport lattices. Results are verified with 3D self-consistent particle-in-cell simulations based on intense beam experiments associated with driver development for heavy-ion fusion.

  5. Low-Stress Upper Plate Near Subduction Zones and Implications for Temporal Changes in Loading Forces

    Science.gov (United States)

    Wang, K.; Hu, Y.; Yoshida, K.

    2016-12-01

    Subduction megathrusts are weak, often with effective friction coefficients as low as 0.03. Consequently, differential stress (S1 - S3) in the nearby upper plate is low. Compression due to plate coupling and tension due to gravity are in a subtle balance that can be tipped by small perturbations. For example, the 2011 M=9 Tohoku-oki earthquake, which has a rupture-zone-average stress drop of only a few MPa, switched offshore margin-normal stress from compression to tension and affected seismicity pattern and stress directions of various parts of the land area. The low differential stress is also reflected in spatial variations of stresses, such as with changes in topography. In the Andes, crustal earthquake focal mechanisms change from thrust-faulting in low-elevation areas to normal-faulting in high-elevation areas. Given the lack of evidence for a pervasively weak crust, the low differential stress may indicate that in general the crust near subduction zones is not critically stressed. If so, crustal earthquakes do not represent pervasive failure but only local failure due to stress, material, and fluid pressure heterogeneity. If distributed permanent deformation that creates topography is not the norm, it either happens in brief episodes or took place in the past. The outer wedge may enter a compressively or extensionally critical state due to coseismic strengthening or weakening, respectively, of the shallow megathrust in largest interplate earthquakes. Temporal changes in loading forces must occur also at much larger temporal and spatial scales in response to changes in the nature of the subducting plate and other tectonic conditions. We propose that submarine wedges and high topography in the upper plate attain their geometry in geologically brief episodes of high differential stress. They normally stay in a low-stress stable state, but their geometry often reflects high-stress episodes of critical states in the past. In other words, rocks have a sustained

  6. 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

  7. Lasting mantle scars lead to perennial plate tectonics.

    Science.gov (United States)

    Heron, Philip J; Pysklywec, Russell N; Stephenson, Randell

    2016-06-10

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a 'perennial' phenomenon.

  8. Lasting mantle scars lead to perennial plate tectonics

    Science.gov (United States)

    Heron, Philip J.; Pysklywec, Russell N.; Stephenson, Randell

    2016-06-01

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a `perennial' phenomenon.

  9. The transition from linear to diffuse plate boundary in the Azores-Gibraltar region: results from a thin-sheet model

    Science.gov (United States)

    Jiménez-Munt, Ivone; Fernàndez, Manel; Torne, Montse; Bird, Peter

    2001-10-01

    We use the thin-sheet plane-stress approach to study the present-day dynamic behavior of the plate boundary between Eurasia and Africa along the Azores-Gibraltar region. This plate boundary, which extends from the Azores triple junction to the Gibraltar strait, shows a tectonic regime that changes from transtension in the west to transpression in the east, with a strike-slip motion in its central segment. Seismological data reveal that the western and central segments are currently marked by a linear series of earthquakes indicating that the plate boundary is located in a narrow zone. In contrast, the eastern segment is not so well defined and deformation spreads over a much broader area. To apply the thin-sheet approach, we combined heat flow, elevation and crustal thickness data to calculate the steady-state geotherm and the total strength of the lithosphere. Several models with different fault friction coefficients and geometries at the eastern segment of the plate boundary were tested. Results are compared with the maximum compressive stress directions from the World Stress Map, and the calculated seismic strain rates and slip vectors from earthquake data. The best fitting models are consistent with the rotation pole of Argus et al. [D.F. Argus et al., J. Geophys. Res. 94 (1989) 5585-5602], and show that the rheological behavior of the plate boundary must necessarily change from the western and central segments to the eastern segment. The diffuse character of the plate boundary east of the Gorringe Bank is dominated by the transition from oceanic to continental lithosphere, the weakness of the Alboran domain, and the convergence between the African and the Eurasian plates. The displacement of the Alboran domain relative to the African plate may play a major role in stress propagation through the Iberian Peninsula and its Atlantic margin.

  10. Non-Similar Computational Solution for Boundary Layer Flows of Non-Newtonian Fluid from an Inclined Plate with Thermal Slip

    Directory of Open Access Journals (Sweden)

    SUBBARAO ANNASAGARAM

    2016-01-01

    Full Text Available The laminar boundary layer flow and heat transfer of Casson non-Newtonian fluid from an inclined (solar collector plate in the presence of thermal and hydrodynamic slip conditions is analysed. The inclined plate surface is maintained at a constant temperature. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite-difference scheme. Increasing velocity slip induces acceleration in the flow near the inclined plate surface. Increasing velocity slip consistently enhances temperatures throughout the boundary layer regime. An increase in thermal slip parameter strongly decelerates the flow and also reduces temperatures in the boundary layer regime. An increase in Casson rheological parameter acts to elevate considerably the velocity and this effect is pronounced at higher values of tangential coordinate. Temperatures are however very slightly decreased with increasing values of Casson rheological parameter.

  11. Elastic-plastic contact force history and response characteristics of circular plate subjected to impact by a projectile

    Institute of Scientific and Technical Information of China (English)

    L. B. Chen; F. Xi; J. L. Yang

    2007-01-01

    A new elastic-plastic impact-contact model is proposed in this paper. By adopting the principle of minimum acceleration for elastic-plastic continue at finite deformation,and with the aid of finite difference method, the proposed model is applied in the problem of dynamic response of a clamped thin circular plate subjected to a projectile impact centrally. The impact force history and response characte-ristics of the target plate is studied in detail. The theoreti-cal predictions of the impact force and plate deflection are in good agreements with those of LDA experimental data.Linear expressions of the maximum impact force/transverse deflection versus impact velocity are given on the basis of the theoretical results.

  12. Thermally developing forced convection and the corresponding thermal stresses in a porous plate channel

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao; LIU Xuemei

    2007-01-01

    Based on the Darcy fluid model, by considering the effects of viscous dissipation due to the interaction between solid skeleton and pore fluid flow and thermal conduction in the direction of the fluid flow, the thermally developing forced convection of the local thermal equili- brium and the corresponding thermal stresses in a semi- infmite saturated porous plate channel are investigated in this paper. The expressions of temperature, local Nusselt number and corresponding thermal stresses are obtained by means of the Fourier series, and the distributions of the same are also shown. Furthermore, influences of the Péclet number (Pe) and Brinkman number (Br) on temperature, Nusselt number (Nu) and thermal stress are revealed numerically.

  13. Study of natural and forced heat transfer coefficients on a vertical heated plate

    Directory of Open Access Journals (Sweden)

    Stefan-Mugur SIMIONESCU

    2015-12-01

    Full Text Available Infrared thermography measurement technique is a methodology which detects infrared energy emitted from an object, converts it to temperature, and displays images of temperature distribution. It is a powerful non-invasive methodology for the analysis of surface temperature measurements. The infrared camera represents a truly two-dimensional transducer, allowing for considerably high accurate measurements of surface temperature maps even in the presence of relatively high spatial gradients. The infrared thermography measurement technique is used in this experimental study to estimate the heat transfer coefficient over a flat plate. The main objective of this study was to get insights about the heat transfer in solids and on solid surfaces and its quantitative measurement. An infrared camera was used to calculate the temperature distribution for the evaluation of the heat transfer coefficient. Two study cases were taken into account: a first case without any fluid jet is calculated, where natural convection over the plate emerges due to the buoyancy effect, and a second case where a circular air jet is impinged on the surface - in this case the forced convection heat transfer coefficient has been evaluated.

  14. The Plate Boundary Observatory Cascadia Network: Development and Installation of a Large Scale Real-time GPS Network

    Science.gov (United States)

    Austin, K. E.; Blume, F.; Berglund, H. T.; Feaux, K.; Gallaher, W. W.; Hodgkinson, K. M.; Mattioli, G. S.; Mencin, D.

    2014-12-01

    The EarthScope Plate Boundary Observatory (PBO), through a NSF-ARRA supplement, has enhanced the geophysical infrastructure in in the Pacific Northwest by upgrading a total of 282 Plate Boundary Observatory GPS stations to allow the collection and distribution of high-rate (1 Hz), low-latency (BGAN satellite communications systems has been conducted to support the Cascadia RT-GPS upgrades and the installation of three BGAN satellite fail over systems along the Cascadia margin will allow for the continuation of data flow in the event of a loss of primary communications during in a large geophysical event or other interruptions in commercial cellular networks. In summary, with these additional upgrades in the Cascadia region, the PBO RT-GPS network will increase to 420 stations. Upgrades to the UNAVCO data infrastructure included evaluation and purchase of the Trimble Pivot Platform, servers, and additional hardware for archiving the high rate data, as well as testing and implementation of GLONASS and Trimble RTX positioning on the receivers. UNAVCO staff is working closely with the UNAVCO community to develop data standards, protocols, and a science plan for the use of RT-GPS data.

  15. New Evidences for Preserved Segmentation of the Alpine-Tethyan Domain in the Iberia-Africa Plate Boundary Region

    Science.gov (United States)

    Fernandez, M.; Torne, M.; Verges, J.; Buffett, G. G.

    2015-12-01

    Based on gravity analysis and previous integrated studies combining potential fields and seismic data, we demonstrate that the Iberia-Africa plate boundary region is characterized by several tectonically inverted transtensional domains inherited from the Jurassic. Gravity data, when filtered for short wavelengths, show conspicuous positive Bouguer anomalies associated with the Gorringe Bank, the Guadalquivir Bank and the Ronda/Beni-Bousera peridotitic massifs. Gravity modelling combined with seismic and geological data shows that the filtered Bouguer anomalies are compatible with relatively high-density and shallow-buried bodies, which correspond to partly serpentinized peridotitic slices with similar densities and geometries as those proved for the Gorringe Bank. The study indicates that the Alpine convergence between Africa and Iberia since Late Cretaceous times reactivated these transtensional domains, which were less deformed westwards and thus preserved their segmentation. The interpretation of these Bouguer anomalies and their distribution substantiates the double-polarity subduction model proposed for the region, and agrees with the present-day seismically diffuse character of the Iberia-Africa plate boundary.

  16. Accurate computation of surface stresses and forces with immersed boundary methods

    Science.gov (United States)

    Goza, Andres; Liska, Sebastian; Morley, Benjamin; Colonius, Tim

    2016-09-01

    Many immersed boundary methods solve for surface stresses that impose the velocity boundary conditions on an immersed body. These surface stresses may contain spurious oscillations that make them ill-suited for representing the physical surface stresses on the body. Moreover, these inaccurate stresses often lead to unphysical oscillations in the history of integrated surface forces such as the coefficient of lift. While the errors in the surface stresses and forces do not necessarily affect the convergence of the velocity field, it is desirable, especially in fluid-structure interaction problems, to obtain smooth and convergent stress distributions on the surface. To this end, we show that the equation for the surface stresses is an integral equation of the first kind whose ill-posedness is the source of spurious oscillations in the stresses. We also demonstrate that for sufficiently smooth delta functions, the oscillations may be filtered out to obtain physically accurate surface stresses. The filtering is applied as a post-processing procedure, so that the convergence of the velocity field is unaffected. We demonstrate the efficacy of the method by computing stresses and forces that converge to the physical stresses and forces for several test problems.

  17. "Atomic Force Masking" Induced Formation of Effective Hot Spots along Grain Boundaries of Metal Thin Films.

    Science.gov (United States)

    Kim, Kwang Hyun; Chae, Soo Sang; Jang, Seunghun; Choi, Won Jin; Chang, Hyunju; Lee, Jeong-O; Lee, Tae Il

    2016-11-30

    We present an interesting phenomenon, "atomic force masking", which is the deposition of a few-nanometer-thick gold film on ultrathin low-molecular-weight (LMW) polydimethylsiloxane (PDMS) engineered on a polycrystalline gold thin film, and demonstrated the formation of hot spot based on SERS. The essential principle of this atomic force masking phenomenon is that an LMW PDMS layer on a single crystalline grain of gold thin film would repel gold atoms approaching this region during a second cycle of evaporation, whereas new nucleation and growth of gold atoms would occur on LMW PDMS deposited on grain boundary regions. The nanostructure formed by the atomic force masking, denoted here as "hot spots on grain boundaries" (HOGs), which is consistent with finite-difference time-domain (FDTD) simulation, and the mechanism of atomic force masking were investigated by carrying out systematic experiments, and density functional theory (DFT) calculations were made to carefully explain the related fundamental physics. Also, to highlight the manufacturing advantages of the proposed method, we demonstrated the simple synthesis of a flexible HOG SERS, and we used this substrate in a swabbing test to detect a common pesticide placed on the surface of an apple.

  18. Solar energy dryer kinetics using flat-plate finned collector and forced convection for potato drying

    Science.gov (United States)

    Batubara, Fatimah; Misran, Erni; Dina, Sari Farah; Heppy

    2017-06-01

    Research on potato drying using the indirect solar dryer with flat-plate finned collector and forced convection has been done. The research was conducted at the outdoor field of Laboratory of Institute for Research and Standardization of Industry on June 14th-23rd, 2016 from 9:00 am to 4:00 pm. This research aims to obtain the drying kinetics model of potato (Solanumtuberosum L.) using an indirect solar dryer's (ISD) with flat plate-finned collector and forced convection. The result will be compared to the open sun drying (OSD) method. Weather conditions during the drying process took place as follows; surrounding air temperature was in the range 27 to 34.7 °C, relative humidity (RH) 29.5 to 61.0% and the intensity of solar radiation 105.6 to 863.1 Watt/m2. The dried potato thicknesses were 1.0 cm, 1.5 cm and 2.0 cm, with the average initial water content of 76.46%. The average temperature in the collector chamber ranged from 42.2 to 57.4 °C and the drying chamber was at 46.2 °C. The best drying result was obtained from a sample size of 1 cm thickness using the IDS method with an average drying rate of 0.018 kg H2O per kg dry-weight.hour and the water content was constant at 5.02% in 21 hours of drying time. The most suitable kinetics model is Page model, equation MR = exp (-0.049 t1,336) for 1.0 cm thickness, exp (-0.066 t1,222) for 1.5 cm thickness and exp (-0.049 t1,221) for 2.0 cm thickness. The quality of potato drying using ISD method is better than using OSD which can be seen from the color produced.

  19. Force plate targeting has no effect on spatiotemporal gait measures and their variability in young and healthy population.

    Science.gov (United States)

    Verniba, Dmitry; Vergara, Martin E; Gage, William H

    2015-02-01

    Force plate targeting has been referenced as a confounding factor in gait research, but the literature is sparse. Asking participants to target force plates is a convenient strategy to increase the number of acceptable trials, but may inadvertently alter the motor control of gait and limit external validity. This study aimed to investigate the effect of visual targeting on spatiotemporal, kinematic, and kinetic measures of gait and their variability. Young healthy participants were asked to traverse a walkway with three embedded hidden force plates. Starting from a participant-specific initial position and leading with the same foot each time, participants performed series of natural walking trials (no targeting and unaware of the hidden force plates), followed by targeting walking trials. For the targeting trials, participants were asked to step completely within the bounds of a tape outline (∼50cm×45cm), which coincided with the position of the last hidden force plate. The results demonstrated evidence of targeting during targeting trials; compared to natural walking trials, mean heel-target distance variability for targeting trials decreased progressively for the steps approaching the targeting step, reaching significance (ptarget (41%), and post-target steps (39%). Despite visual targeting, no significant differences between targeting and natural trials were detected in spatiotemporal, kinematic, and kinetic gait measures, or the variability of the measures. When the experimental set-up was tailored to the individual participant's gait variables (step/stride length), visual targeting of the force plates appeared to have no effect on the magnitude or variability of any gait measures.

  20. Entropic transport without external force in confined channel with oscillatory boundary

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Huai; Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics & Hefei National Laboratory for Physical Sciences at Microscales, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-12-28

    The dynamics of point-like Brownian particles in a periodic confined channel with oscillating boundaries has been studied. Directional transport (DT) behavior, characterized by net displacement along the horizontal direction, is observed even without external force which is necessary for the conventional DT where the boundaries are static. For typical parameter values, the average velocity V{sub t} of DT reaches a maximum with the variation of the noise intensity D, being alike to the phenomenon of stochastic resonance. Interestingly, we find that V{sub t} shows nontrivial dependences on the particle gravity G depending on the noise level. When the noise is large, V{sub t} increases monotonically with G indicating that heavier particle moves faster, while for small noise, V{sub t} shows a bell-shape dependence on G, suggesting that a particle with an intermediate weight may move the fastest. Such results were not observed for DT in a channel with static boundaries. To understand these findings, we have adopted an effective one-dimensional coarsening description, which facilitates us to introduce an effective entropic force along the horizontal direction. The average force is apparently nonzero due to the oscillatory boundary, hence leading to the net transport, and it shows similar dependences as V{sub t} on the noise intensity D and particle gravity G. The dependences of the DT behavior on other parameters describing the oscillatory channel have also been investigated, showing that DT is more pronounced for larger oscillation amplitude and frequency, and asymmetric geometry within a channel period and phase difference between neighboring periods are both necessary for the occurrence of DT.

  1. 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.

  2. 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

  3. On the Estimation of Spanwise Pressure Coherence of a Turbulent Boundary Layer over a Flat Plate

    NARCIS (Netherlands)

    Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.

    2014-01-01

    A Large Eddy Simulation (LES) with four different closure models are analyzed in OpenFOAM, an open source Computional Fluid Dynamics (CFD) package and validated for the determination of the streamwise and spanwise coherence length of the pressure field below a turbulent boundary layer at low

  4. Quantifying the strain due to grain boundary sliding of forsterite using atomic force microscopy

    Science.gov (United States)

    Dillman, A. M.; Kohlstedt, D. L.

    2016-12-01

    Grain boundary sliding (GBS) is a deformation process that requires either diffusion or dislocation motion in order to maintain fully dense samples and deform at a steady-state strain rate. When accommodated by diffusion (diffusion creep), this deformation is characterized by a Newtonian viscosity with a strong dependence on grain size. To better understand the combination of diffusion and sliding, explicit measurements of the degree of grain boundary sliding, taken at a very fine scale, are necessary. High purity, synthetic forsterite was chosen to study the contribution of GBS, as it can be created with a grain size of 1 μm and its relatively sluggish grain growth kinetics limit the grain size to generally right prisms, with at least one face polished flat. This face, oriented parallel to the applied stress, was imaged using atomic force microscopy after deformation. The amount of strain due to grain boundary sliding was determined using high resolution measurements of topography. A methodology was developed to account for thermal grooving of the polished face and to objectively quantify the ratio of grain boundary sliding strain to total strain, ξ. For the differential stresses applied, ξ = 63%. This ratio was independent of strain and decreased slightly with increasing grain size. This value of 63% is very similar to experimentally determined values of ξ for pure, fine grained alumina. With this new methodology for determining the strain due to grain boundary sliding, we will be able to determine the point of transition between different deformation regimes that require different contributions of grain boundary sliding.

  5. Moments About Body Centered Coordinate Axes At Limb Joints From Force Plate And Biplane Photography Measurements

    Science.gov (United States)

    Balakrishnan, S.; Thornton-Trump, A. B.; Brodland, G. W.

    1983-07-01

    Traditional locomotion analysis considers motion in a translating coordinate frame and the analysis is performed primarily in the sagittal plane. The results of several studies in the present work have shown that the aspect of symmetry is rarely present in pathological gait. Loss of function in one plane of movement gives rise to larger motions in other planes. This brings into focus the necessity for three dimensional measurement for adequately representing pathological gait. Description of quantities associated with gait in the appropriate moving frame of each segment would be closer to joint angulation of limb segments. Although this description has been attempted by a few researchers, the assumption of small angle theory and vectorial addition of rotation angles commonly employed for defining the rotation matrices is not applicable to pathological gait. The present work illustrates the use of biplane photography for displacement measurement in human movement. Transformations based on Eulerian angle rotations are derived based on biplane measurements. From the three dimensional ground reaction forces measured by a force plate, moments about the moving upper body coordinate axes are computed through a three dimensional mathematical model.

  6. Turbulent Friction in the Boundary Layer of a Flat Plate in a Two-Dimensional Compressible Flow at High Speeds

    Science.gov (United States)

    Frankl, F.; Voishel, V.

    1943-01-01

    In the present report an investigation is made on a flat plate in a two-dimensional compressible flow of the effect of compressibility and heating on the turbulent frictional drag coefficient in the boundary layer of an airfoil or wing radiator. The analysis is based on the Prandtl-Karman theory of the turbulent boundary later and the Stodola-Crocco, theorem on the linear relation between the total energy of the flow and its velocity. Formulas are obtained for the velocity distribution and the frictional drag law in a turbulent boundary later with the compressibility effect and heat transfer taken into account. It is found that with increase of compressibility and temperature at full retardation of the flow (the temperature when the velocity of the flow at a given point is reduced to zero in case of an adiabatic process in the gas) at a constant R (sub x), the frictional drag coefficient C (sub f) decreased, both of these factors acting in the same sense.

  7. "Discovering Plate Boundaries in Data-Rich Environments": Supporting Pre-service Teachers involvement in Unique Practices of Geosciences

    Science.gov (United States)

    Barrie, A. S.; Moore, J.

    2012-12-01

    plate tectonics using key scientific practices. As a result of the educational activities developed in this project, we will try help teachers to overcome their challenges and develop the pedagogical skills that novice teachers need to use to teach plate tectonics by focusing on key scientific practices with the help of previously-developed educational resources. Learning about the processes that occur at plate boundaries will help future teachers (and their students) understand natural disasters such as earthquakes and volcanoes. Furthermore, the study will have a significant, and broader, impact by 'teaching the teachers' and empowering novice teachers to overcome the challenges of reading maps and using argumentation in science classrooms.

  8. Water Release from Cold Serpentinized Forearc Mantle During Subduction Associated with Changes in Incoming Oceanic Plate Thermal Structure and Plate Boundary Kinematics: New Insights

    Science.gov (United States)

    Kirby, S. H.

    2015-12-01

    Kirby, Wang, and Brocher (Earth Planets and Space, 2014) recently showed how the change in kinematics of the California margin from subduction motion to continental transform motion with the birth and growth of the San Andreas Fault System (SAFS) beginning at about 33 Ma BP likely led to a warming of the former forearc mantle and the release of water by serpentinite dehydration. Such discharges from serpentinized mantle increase fluid pressures along the SAFS under the Coast Ranges and this gives insights into both the low sliding resistance for the SAFS and the mobilization and ascent of some serpentinized mantle peridotites through the crust. Thermal modeling by others has also shown that changes in the incoming plate age and subduction rate can also lead to warming of the forearc mantle during subduction. This development gives insights into the Mesozoic and Paleogene ages of emplacement of some, but not all, California serpentinites. Recent mineralogical and geochemical observations of serpentinized blocks in serpentinize mélange bodies in the San Francisco Bay Area (Uno and Kirby, 2015; Lewis and Kirby, 2015, this session) suggest that these rocks sustained multiple stages of serpentinization that are broadly consistent with the model of Kirby et al. (2014). Previous studies of localized late-stage silica-carbonate-water alteration of serpentinite bodies in California by carbonated water suggest that this alteration occurred largely in Neogene time when the highest rate of water release from the former forearc mantle probably happened. I also suggest that the occurrence of serpentinite belts emplaced in Cenozoic time during changing plate-boundary kinematics, such as the Cenozoic closing of the Tethys Ocean bordering Eurasia and arc reversal and decreasing convergence rates under the Greater Antilles, may give insights into the serpentinite belts in those regions.

  9. Hypersonic Laminar Boundary Layer Velocimetry with Discrete Roughness on a Flat Plate

    Science.gov (United States)

    Bathel, Brett; Danehy, Paul M.; Inman, Jennifer A.; Watkins, A. Neal; Jones, Stephen B.; Lipford, William E.; Goodman, Kyle Z.; Ivey, Christopher B.; Goyne, Christopher P.

    2010-01-01

    Laminar boundary layer velocity measurements are made on a 10-degree half-angle wedge in a Mach 10 flow. Two types of discrete boundary layer trips were used to perturb the boundary layer gas. The first was a 2-mm tall, 4-mm diameter cylindrical trip. The second was a scaled version of the Orbiter Boundary Layer Transition (BLT) Detailed Test Objective (DTO) trip. Both 1-mm and 2.5-mm tall BLT DTO trips were tested. Additionally, side-view and plan-view axial boundary layer velocity measurements were made in the absence of these tripping devices. The free-stream unit Reynolds numbers tested for the cylindrical trips were 1.7x10(exp 6)/m and 3.3x10(exp 6)/m. The free-stream unit Reynolds number tested for the BLT DTO trips was 1.7x10(exp 6)/m. The angle of attack was kept at approximately 5-degrees for most of the tests resulting in a Mach number of approximately 8.3. These combinations of unit Reynolds numbers and angle of attack resulted in laminar flowfields. To study the precision of the measurement technique, the angle of attack was varied during one run. Nitric-oxide (NO) molecular tagging velocimetry (MTV) was used to obtain averaged axial velocity values and associated uncertainties. These uncertainties are as low as 20 m/s. An interline, progressive scan CCD camera was used to obtain separate images of the initial reference and shifted NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond sequential acquisition of both images. The maximum planar spatial resolution achieved for the side-view velocity measurements was 0.07-mm in the wall-normal direction by 1.45-mm in the streamwise direction with a spatial depth of 0.5-mm. For the plan-view measurements, the maximum planar spatial resolution in the spanwise and streamwise directions was 0.69-mm by 1.28-mm, respectively, with a spatial depth of 0.5-mm. Temperature sensitive paint (TSP) measurements are provided to compliment the velocity data and to provide further

  10. Convergence of Phase-Field Free Energy and Boundary Force for Molecular Solvation

    Science.gov (United States)

    Dai, Shibin; Li, Bo; Lu, Jianfeng

    2017-08-01

    We study a phase-field variational model for the solvation of charged molecules with an implicit solvent. The solvation free-energy functional of all phase fields consists of the surface energy, solute excluded volume and solute-solvent van der Waals dispersion energy, and electrostatic free energy. The surface energy is defined by the van der Waals-Cahn-Hilliard functional with squared gradient and a double-well potential. The electrostatic part of free energy is defined through the electrostatic potential governed by the Poisson-Boltzmann equation in which the dielectric coefficient is defined through the underlying phase field. We prove the continuity of the electrostatics—its potential, free energy, and dielectric boundary force—with respect to the perturbation of the dielectric boundary. We also prove the {Γ} -convergence of the phase-field free-energy functionals to their sharp-interface limit, and the equivalence of the convergence of total free energies to that of all individual parts of free energy. We finally prove the convergence of phase-field forces to their sharp-interface limit. Such forces are defined as the negative first variations of the free-energy functional; and arise from stress tensors. In particular, we obtain the force convergence for the van der Waals-Cahn-Hilliard functionals with minimal assumptions.

  11. Thermohaline forcing of eastern boundary currents: With application to the circulation off the west coast of Australia

    Digital Repository Service at National Institute of Oceanography (India)

    McCreary, J.P.; Shetye, S.R.; Kundu, P.K.

    . This interior current forces downwelling at an eastern ocean boundary, and generates a poleward surface coastal current and an equatorward undercurrent. For realistic choices of model parameters the coastal circulation is as strong as, and opposite in direction...

  12. Direct force wall shear measurements in pressure-driven three-dimensional turbulent boundary layers

    Science.gov (United States)

    Mcallister, J. E.; Tennant, M. H.; Pierce, F. J.

    1982-01-01

    Unique, simultaneous direct measurements of the magnitude and direction of the local wall shear stress in a pressure-driven three-dimensional turbulent boundary layer are presented. The flow is also described with an oil streak wall flow pattern, a map of the wall shear stress-wall pressure gradient orientations, a comparison of the wall shear stress directions relative to the directions of the nearest wall velocity as measured with a typical, small boundary layer directionally sensitive claw probe, as well as limiting wall streamline directions from the oil streak patterns, and a comparison of the freestream streamlines and the wall flow streamlines. A review of corrections for direct force sensing shear meters for two-dimensional flows is presented with a brief discussion of their applicability to three-dimensional devices.

  13. Measurement of the impuslive force generated by colapsing bubble close to a solid boundary

    Directory of Open Access Journals (Sweden)

    Zima Patrik

    2012-04-01

    Full Text Available The article presents experimental results of the acoustical and optical study of cavitation bubble collapse close to a solid boundary in water. The bubble was generated by discharge of low-voltage capacitor into a couple of wires closing a simple circuit. Different distances from the solid wall and different maximum bubble radii were studied. The bubble radius was studied using time-resolved photography and by PVDF film sensor glued on the solid boundary. The illumination was provided by high-power led diode. Synchronization of the system was provided by pulse generator connected to an oscilloscope. The impact power of the bubble to the wall was estimated from the time-resolved photography of the bubble and from the PVDF film sensor signal. The PVDF film sensor calibration was performed by a pendulum test to estimate the impact force.

  14. The effects of forcing on a single stream shear layer and its parent boundary layer

    Science.gov (United States)

    Haw, Richard C.; Foss, John F.

    1990-01-01

    Forcing and its effect on fluid flows has become an accepted tool in the study and control of flow systems. It has been used both as a diagnostic tool, to explore the development and interaction of coherent structures, and as a method of controlling the behavior of the flow. A number of forcing methods have been used in order to provide a perturbation to the flow; among these are the use of an oscillating trailing edge, acoustically driven slots, external acoustic forcing, and mechanical piston methods. The effect of a planar mechanical piston forcing on a single stream shear layer is presented; it can be noted that this is one of the lesser studied free shear layers. The single stream shear layer can be characterized by its primary flow velocity scale and the thickness of the separating boundary layer. The velocity scale is constant over the length of the flow field; theta (x) can be used as a width scale to characterize the unforced shear layer. In the case of the forced shear layer the velocity field is a function of phase time and definition of a width measure becomes somewhat problematic.

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

    Energy Technology Data Exchange (ETDEWEB)

    Adesanya, S.O., E-mail: adesanyas@run.edu.ng [Department of Mathematical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Oluwadare, E.O. [Department of Mathematical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Falade, J.A., E-mail: faladej@run.edu.ng [Department of Physical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Makinde, O.D., E-mail: makinded@gmail.com [Faculty of Military Science, Stellenbosch University, Private Bag X2, Saldanha 7395 (South Africa)

    2015-12-15

    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. Isla Guadalupe, a Plate Boundary Observatory Remote GPS System: What's Next in PBO-Mexico?

    Science.gov (United States)

    Gonzalez Garcia, J.

    2003-12-01

    As a join project between scientific and technical personnel from Southern California Integrated GPS Network, the University NAVSTAR Consortium, Nanometrics Inc, and CICESE, we installed a VSAT remote communications on Isla Guadalupe in support of data telemetry from a cluster of GPS, meteorological and seismic instrumentation. This Mexican island located between 28\\deg53' and 29\\deg 11'N and 118\\deg 13' to 118\\deg 22'W, lies too far from the main land to allow regular radio link. The station now in operation (GUAX) is near of the early GEOMEX site (GUAD), which recent GPS survey mode result show, is fully located on the Pacific plate within the prediction (1 mm/yr N and 2 mm/yr E) of both the geophysical (NNR-NUVEL1-A) and geodetic (ITRF2000) Plate Tectonic models. Thus, GUAX serve as an important clue to accurately monitor the plate's motion, as well as a reference for studies of California Borderland deformation. During the last 5 years we have built two more sites in northern Baja California: SPMX (1998) and CORX (2000); these together with the IGS station in Ensenada (CICE established in 1995 and replaced by CIC1 in 1999), became part of SCIGN-SOPAC (http://sopac.ucsd.edu, www.scign.org). In Mexico the major organizations working with GPS are INEGI (15 sites) and UNAM (different groups: 20-25 sites). Other State Universities and agencies are increasingly using permanent GPS stations for diverse purposes. It seems that in order to achieve our commitment for PBO-Mexico we must to follow the PGGA/SCIGN/CSRC waybill.

  17. Transients in Pacific/North American Plate Boundary Deformation: Synthesis and Modeling of GPS and Borehole Strain Observations

    Science.gov (United States)

    Solomon, Sean C.; Frey, H. V. (Technical Monitor)

    2002-01-01

    This is the Final Technical Report on research conducted between 1 June 1997 and 14 September 2001 entitled "Transients in Pacific/North American plate boundary deformation: Synthesis and modeling of GPS and borehole strain observations." As the project title implies, our effort involved a geodetic study of strain transients, i.e., temporal variations in deformation rates, that occur within plate boundary zones and their relationship to earthquakes and plate motions. Important transients occur during and following large earthquakes, and there are also strain transients not apparently associated with earthquakes. A particularly intriguing class of transients, for which there is a modest but growing list of examples, are preseismic anomalies. Such earthquake precursors, if further documented and understood, would have obvious importance for earthquake hazard mitigation. Because the timescales for these diverse transients range over at least 6 orders of magnitude (minutes to years), no single geodetic technique is optimum. We therefore undertook a systematic synthesis of Global Positioning Satellite (GPS) and borehole strainmeter data in three areas in California where there are adequate numbers of both types of instruments (or their equivalent): the San Francisco Bay region (within the Bay Area Regional Deformation network), southern California (within the Southern California Integrated GPS Network), and Parkfield (where a two-color laser system provides a proxy for continuous GPS measurements). An integral component of our study was the elucidation of the physical mechanisms by which such transients occur and propagate. We therefore initiated the development of multiple forward models, using two independent approaches. In the first, we explored the response to specified earthquake slip in viscoelastic models that incorporated failure criteria and the geometry of major faults in California. In the second approach, we examined the dynamical response of a complex

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

    Energy Technology Data Exchange (ETDEWEB)

    Song, Woo Seog; Lee, Seung Bae [Inha University, Incheon (Korea, Republic of); Shin, Dong Shin [Hongik University, Seoul (Korea, Republic of); Na, Yang [Konkuk University, Seoul (Korea, Republic of)

    2006-11-15

    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{sub b}{sup +} =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 700{nu}/u{sub {tau}}-long bimorph film is periodically actuated at the non-dimensional frequency f{sub b}{sup +} =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.

  19. Boundary Effects in Quantum Physics

    CERN Document Server

    Asorey, M

    2013-01-01

    We analyze the role of boundaries in the infrared behavior of quantum field theories. By means of a novel method we calculate the vacuum energy for a massless scalar field confined between two homogeneous parallel plates with the most general type of boundary properties. This allows the discrimination between boundary conditions which generate attractive or repulsive Casimir forces between the plates. In the interface between both regimes we find a very interesting family of boundary conditions which do not induce any type of Casimir force. We analyze the effect of the renormalization group flow on these boundary conditions. Even if the Casimirless conformal invariant conditions are physically unstable under renormalization group flow they emerge as a new set of conformally invariant boundary conditions which are anomaly free.

  20. Mixed convection boundary layer flow past vertical flat plate in nanofluid:case of prescribed wall heat flux

    Institute of Scientific and Technical Information of China (English)

    R. TRˆIMBIT¸AS¸; T.GROSAN; I.POP

    2015-01-01

    An analysis is carried out to investigate the steady mixed convection bound-ary layer flow of a water based nanofluid past a vertical semi-infinite flat plate. Using an appropriate similarity transformation, the governing partial differential equations are transformed into the coupled, nonlinear ordinary (similar) differential equations, which are then solved numerically for the Prandtl number Pr = 6.2. The skin friction coeffi-cient, the local Nusselt number, and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fractionφand the mixed convection parameterλon the fluid flow and heat transfer characteristics are thoroughly examined. Different from an assisting flow, it is found that the solutions for an opposing flow are non-unique. In order to establish which solution branch is stable and physically realizable in practice, a stability analysis is performed.

  1. Double diffusive magnetohydrodynamic (MHD) mixed convective slip flow along a radiating moving vertical flat plate with convective boundary condition.

    Science.gov (United States)

    Rashidi, Mohammad M; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J; Freidoonimehr, Navid

    2014-01-01

    In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, [Formula: see text], local Nusselt number, [Formula: see text], and local Sherwood number [Formula: see text] are shown and explained through tables.

  2. 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.

  3. 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.

  4. Double Diffusive Magnetohydrodynamic (MHD) Mixed Convective Slip Flow along a Radiating Moving Vertical Flat Plate with Convective Boundary Condition

    Science.gov (United States)

    Rashidi, Mohammad M.; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J.; Freidoonimehr, Navid

    2014-01-01

    In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, , local Nusselt number, , and local Sherwood number are shown and explained through tables. PMID:25343360

  5. 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.

  6. Response to rotating forcing of the von-Karman disk boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Mukund; Siddiqui, M Ehtisham; Pier, Benoit; Scott, Julian; Azouzi, Alexandre; Michelet, Roger; Nicot, Christian, E-mail: benoit.pier@ec-lyon.fr [Laboratoire de mecanique des fluides et d' acoustique (CNRS-Universite de Lyon) Ecole centrale de Lyon, 36 avenue Guy-de-Collongue, 69134 Ecully (France)

    2011-12-22

    In the present experimental investigation of the three-dimensional boundary layer due to a disk rotating in otherwise still air, the aim is to study the response to a radially localized perturbation applied with a prescribed relative frequency with respect to the disk. The response to localized rotating forcing is measured with a hot-wire probe. The rotation rate of the forcing element is controlled independently of the disk rotation rate, and the dynamics of the spatial response is studied as a function of the ratio between the two rotation rates. The theoretically expected disturbance trajectories are derived from an instability analysis based on the exact local dispersion relations computed from the complete linearized Navier-Stokes equations. Theoretical predictions and experimental measurements are shown to be in good agreement.

  7. An Immersed Boundary method with divergence-free velocity interpolation and force spreading

    Science.gov (United States)

    Bao, Yuanxun; Donev, Aleksandar; Griffith, Boyce E.; McQueen, David M.; Peskin, Charles S.

    2017-10-01

    The Immersed Boundary (IB) method is a mathematical framework for constructing robust numerical methods to study fluid-structure interaction in problems involving an elastic structure immersed in a viscous fluid. The IB formulation uses an Eulerian representation of the fluid and a Lagrangian representation of the structure. The Lagrangian and Eulerian frames are coupled by integral transforms with delta function kernels. The discretized IB equations use approximations to these transforms with regularized delta function kernels to interpolate the fluid velocity to the structure, and to spread structural forces to the fluid. It is well-known that the conventional IB method can suffer from poor volume conservation since the interpolated Lagrangian velocity field is not generally divergence-free, and so this can cause spurious volume changes. In practice, the lack of volume conservation is especially pronounced for cases where there are large pressure differences across thin structural boundaries. The aim of this paper is to greatly reduce the volume error of the IB method by introducing velocity-interpolation and force-spreading schemes with the properties that the interpolated velocity field in which the structure moves is at least C1 and satisfies a continuous divergence-free condition, and that the force-spreading operator is the adjoint of the velocity-interpolation operator. We confirm through numerical experiments in two and three spatial dimensions that this new IB method is able to achieve substantial improvement in volume conservation compared to other existing IB methods, at the expense of a modest increase in the computational cost. Further, the new method provides smoother Lagrangian forces (tractions) than traditional IB methods. The method presented here is restricted to periodic computational domains. Its generalization to non-periodic domains is important future work.

  8. The Garzon fault: active southwestern boundary of the Caribbean plate in Colombia

    Science.gov (United States)

    Chorowicz, J.; Chotin, P.; Guillande, R.

    1996-03-01

    We propose active right-lateral strike-slip motion on the Garzon fault zone of the Neiva basin, Colombia, based on the identification of two active right-stepping releasing bend basins along the fault using stereoscopic analysis of 1/250000 SPOT images. The Garzon fault connects the Bocono-Pamplona-Guaicaramo fault zones of Venezuela and Colombia with the Romeral, Dolores and Guayaquil faults of Colombia. Together these faults form a continuous, active right-lateral fault between accreted terranes in northwestern South America and a more stable South America plate. We infer 5-km right-lateral offset of the Garzon fault based on the width of the Algeciras releasing bend basin.

  9. Plate Boundary Observatory Nucleus Education and Outreach: Bringing GPS and Data- Rich Activities Into College and Secondary Earth Science Classrooms

    Science.gov (United States)

    Walker, B.; Eriksson, S. C.

    2006-05-01

    Incorporating scientific data into the curriculum provides students with insight into elements of the scientific process such as developing questions and hypotheses, understanding how data are collected, evaluating data quality and limitations, and formulating conclusions based on scientific results (Manduca et al., 2003.) UNAVCO, a geodetic consortium and co-administrator of the Plate Boundary Observatory Nucleus project, seeks to increase public appreciation and understanding of Earth deformation processes and their societal relevance through education and outreach. To that end, we are developing place-based instructional materials for college and secondary Earth science classrooms in which GPS data are used to teach students about plate tectonics. To assess the needs of our users, we conducted interviews with college geoscience faculty from a variety of institution types and focus groups with secondary Earth science teachers to solicit feedback on the types of educational materials that they would likely use in their classrooms. We are engaging members of the scientific and educational communities to develop the materials and are catering the modules to accommodate diverse groups of learners and learning styles. In addition, we have completed and scheduled several professional development opportunities on the local and national levels for college and university faculty and secondary teachers and have created a new education and outreach website. Our education programs are being assessed by an external evaluator. We will present interview and focus group results, report on the status of our education programs, and discuss upcoming UNAVCO education activities.

  10. Discovering Plate Boundaries in Data-integrated Environments: Preservice Teachers' Conceptualization and Implementation of Scientific Practices

    Science.gov (United States)

    Sezen-Barrie, Asli; Moore, Joel; Roig, Cara E.

    2015-08-01

    Drawn from the norms and rules of their fields, scientists use variety of practices, such as asking questions and arguing based on evidence, to engage in research that will contribute to our understanding of Earth and beyond. In this study, we explore how preservice teachers' learn to teach scientific practices while teaching plate tectonic theory. In particular, our aim is to observe which scientific practices preservice teachers use while teaching an earth science unit, how do they integrate these practices into their lessons, and what challenges do they face during their first time teaching of an earth science content area integrated with scientific practices. The study is designed as a qualitative, exploratory case study of seven preservice teachers while they were learning to teach plate tectonic theory to a group of middle school students. The data were driven from the video records and artifacts of the preservice teachers' learning and teaching processes as well as written reflections on the teaching. Intertextual discourse analysis was used to understand what scientific practices preservice teachers choose to integrate into their teaching experience. Our results showed that preservice teachers chose to focus on four aspects of scientific practices: (1) employing historical understanding of how the theory emerged, (2) encouraging the use of evidence to build up a theory, (3) observation and interpretation of data maps, and (4) collaborative practices in making up the theory. For each of these practices, we also looked at the common challenges faced by preservice teachers by using constant comparative analysis. We observed the practices that preservice teachers decided to use and the challenges they faced, which were determined by what might have come as in their personal history as learners. Therefore, in order to strengthen preservice teachers' background, college courses should be arranged to teach important scientific ideas through scientific practices

  11. Interior Baja B.C. : Continuing Rotation on a Diffuse Plate Boundary

    Science.gov (United States)

    Symons, D. T.; Harris, M. J.; McCausland, P. J.; Blackburn, W. H.; Hart, C. J.

    2004-12-01

    Interior Baja B.C. - the Intermontane Belt (IMB) and Yukon-Tanana (YT) terranes of northwestern North America - provide a geological record of the complex interactions between the northeastern Pacific basin plates and craton. Geophysical evidence from earthquake seismology, gravity, global positioning system and heat flow data indicate motion of the IMB terranes toward the craton today. Paleomagnetic data show the YT terrane to be parautochthonous and part of the craton's ramp onto which the IMB terranes were obducted. Conversely the IMB terranes behaved as an allochthonous reasonably-coherent microplate with its own apparent polar wander path. Relative to the craton, the path dictates that: 1) from 0-54 Ma the IMB rotated steadily on the craton's ramp at 0.29±±0.11° /Ma or 16±6° clockwise (CW), consistent with Lithoprobe SNORCLE deep crustal seismic evidence for thin skinned tectonics; 2) from 54 to 102±14 Ma the IMB was offshore and was further rotated by 35±14° CW and translated northward by 8.3±7.0° (915±75 km), consistent with geological estimates for total dextral fault displacement and seafloor plate vectors; and 3) more speculatively, from Early Cretaceous to Early Jurassic, the IMB moved in concert with the craton off the western USA seaboard. This history fits with major geologic events such as extensive Eocene extension in southern British Columbia, development of the 1000 km-long Selwyn-Mackenzie orogenic arc in Yukon, YT terrane exposure on either side of the IMB, etc. Further it requires continuing crust-mantle interactions that extend some hundreds of kilometers into the craton today.

  12. 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.

  13. CellFIT: a cellular force-inference toolkit using curvilinear cell boundaries.

    Directory of Open Access Journals (Sweden)

    G Wayne Brodland

    Full Text Available Mechanical forces play a key role in a wide range of biological processes, from embryogenesis to cancer metastasis, and there is considerable interest in the intuitive question, "Can cellular forces be inferred from cell shapes?" Although several groups have posited affirmative answers to this stimulating question, nagging issues remained regarding equation structure, solution uniqueness and noise sensitivity. Here we show that the mechanical and mathematical factors behind these issues can be resolved by using curved cell edges rather than straight ones. We present a new package of force-inference equations and assessment tools and denote this new package CellFIT, the Cellular Force Inference Toolkit. In this approach, cells in an image are segmented and equilibrium equations are constructed for each triple junction based solely on edge tensions and the limiting angles at which edges approach each junction. The resulting system of tension equations is generally overdetermined. As a result, solutions can be obtained even when a modest number of edges need to be removed from the analysis due to short length, poor definition, image clarity or other factors. Solving these equations yields a set of relative edge tensions whose scaling must be determined from data external to the image. In cases where intracellular pressures are also of interest, Laplace equations are constructed to relate the edge tensions, curvatures and cellular pressure differences. That system is also generally overdetermined and its solution yields a set of pressures whose offset requires reference to the surrounding medium, an open wound, or information external to the image. We show that condition numbers, residual analyses and standard errors can provide confidence information about the inferred forces and pressures. Application of CellFIT to several live and fixed biological tissues reveals considerable force variability within a cell population, significant differences

  14. Non-Newtonian particulate flow simulation: A direct-forcing immersed boundary-lattice Boltzmann approach

    Science.gov (United States)

    Amiri Delouei, A.; Nazari, M.; Kayhani, M. H.; Kang, S. K.; Succi, S.

    2016-04-01

    In the current study, a direct-forcing immersed boundary-non-Newtonian lattice Boltzmann method (IB-NLBM) is developed to investigate the sedimentation and interaction of particles in shear-thinning and shear-thickening fluids. In the proposed IB-NLBM, the non-linear mechanics of non-Newtonian particulate flows is detected by combination of the most desirable features of immersed boundary and lattice Boltzmann methods. The noticeable roles of non-Newtonian behavior on particle motion, settling velocity and generalized Reynolds number are investigated by simulating benchmark problem of one-particle sedimentation under the same generalized Archimedes number. The effects of extra force due to added accelerated mass are analyzed on the particle motion which have a significant impact on shear-thinning fluids. For the first time, the phenomena of interaction among the particles, such as Drafting, Kissing, and Tumbling in non-Newtonian fluids are investigated by simulation of two-particle sedimentation and twelve-particle sedimentation. The results show that increasing the shear-thickening behavior of fluid leads to a significant increase in the kissing time. Moreover, the transverse position of particles for shear-thinning fluids during the tumbling interval is different from Newtonian and the shear-thickening fluids. The present non-Newtonian particulate study can be applied in several industrial and scientific applications, like the non-Newtonian sedimentation behavior of particles in food industrial and biological fluids.

  15. 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.

  16. MHD boundary layer slip flow and radiative nonlinear heat transfer over a flat plate with variable fluid properties and thermophoresis

    Directory of Open Access Journals (Sweden)

    S.K. Parida

    2015-12-01

    Full Text Available This work considers the two-dimensional steady MHD boundary layer flow of heat and mass transfer over a flat plate with partial slip at the surface subjected to the convective heat flux. The particular attraction lies in searching the effects of variable viscosity and variable thermal diffusivity on the behavior of the flow. In addition, non-linear thermal radiation effects and thermophoresis are taken into account. The governing nonlinear partial differential equations for the flow, heat and mass transfer are transformed into a set of coupled nonlinear ordinary differential equations by using similarity variable, which are solved numerically by applying Runge–Kutta fourth–fifth order integration scheme in association with quasilinear shooting technique. The novel results for the dimensionless velocity, temperature, concentration and ambient Prandtl number within the boundary layer are displayed graphically for various parameters that characterize the flow. The local skin friction, Nusselt number and Sherwood number are shown graphically. The numerical results obtained for the particular case are fairly in good agreement with the result of Rahman [6].

  17. Magmatism at the Eurasian–North American modern plate boundary: Constraints from alkaline volcanism in the Chersky Belt (Yakutia)

    Science.gov (United States)

    Tschegg, Cornelius; Bizimis, Michael; Schneider, David; Akinin, Vyacheslav V.; Ntaflos, Theodoros

    2011-01-01

    The Chersky seismic belt (NE-Russia) forms the modern plate boundary of the Eurasian−North American continental plate. The geodynamic evolution of this continent−continent setting is highly complex and remains a matter of debate, as the extent and influence of the Mid-Arctic Ocean spreading center on the North Asian continent since the Eocene remains unclear. The progression from a tensional stress regime to a modern day transpressional one in the Chersky seismic belt, makes the understanding even more complicated. The alkaline volcanism that has erupted along the Chersky range from Eocene through to the Recent can provide constraints on the geodynamic evolution of this continental boundary, however, the source and petrogenetic evolution of these volcanic rocks and their initiating mechanisms are poorly understood. We studied basanites of the central Chersky belt, which are thought to represent the first alkaline volcanic activity in the area, after initial opening of the Arctic Ocean basin. We present mineral and bulk rock geochemical data as well as Sr–Nd–Pb–Hf isotopes of the alkaline suite of rocks combined with new precise K–Ar and 40Ar/39Ar dating, and discuss an integrated tectono-magmatic model for the Chersky belt. Our findings show that the basanites were generated from a homogeneous asthenospheric mantle reservoir with an EM-1 isotopic flavor, under relatively ‘dry’ conditions at segregation depths around 110 km and temperatures of ~ 1500 °C. Trace element and isotope systematics combined with mantle potential temperature estimates offer no confirmation of magmatism related to subduction or plume activity. Mineral geochemical and petrographical observations together with bulk geochemical evidence indicate a rapid ascent of melts and high cooling rates after emplacement in the continental crust. Our preferred model is that volcanism was triggered by extension and thinning of the lithosphere combined with adiabatic upwelling of the

  18. How does the 2010 El Mayor - Cucapah Earthquake Rupture Connect to the Southern California Plate Boundary Fault System

    Science.gov (United States)

    Donnellan, A.; Ben-Zion, Y.; Arrowsmith, R.

    2016-12-01

    The Pacific - North American plate boundary in southern California is marked by several major strike slip faults. The 2010 M7.2 El Mayor - Cucapah earthquake ruptured 120 km of upper crust in Baja California to the US-Mexico border. The earthquake triggered slip along an extensive network of faults in the Salton Trough from the Mexican border to the southern end of the San Andreas fault. Earthquakes >M5 were triggered in the gap between the Laguna Salada and Elsinore faults at Ocotillo and on the Coyote Creek segment of the San Jacinto fault 20 km northwest of Borrego Springs. UAVSAR observations, collected since October of 2009, measure slip associated with the M5.7 Ocotillo aftershock with deformation continuing into 2014. The Elsinore fault has been remarkably quiet, however, with only M5.0 and M5.2 earthquakes occurring on the Coyote Mountains segment of the fault in 1940 and 1968 respectively. In contrast, the Imperial Valley has been quite active historically with numerous moderate events occurring since 1935. Moderate event activity is increasing along the San Jacinto fault zone (SJFZ), especially the trifurcation area, where 6 of 12 historic earthquakes in this 20 km long fault zone have occurred since 2000. However, no recent deformation has been detected using UAVSAR measurements in this area, including the recent M5.2 June 2016 Borrego earthquake. Does the El Mayor - Cucapah rupture connect to and transfer stress primarily to a single southern California fault or several? What is its role relative to the background plate motion? UAVSAR observations indicate that the southward extension of the Elsinore fault has recently experienced the most localized deformation. Seismicity suggests that the San Jacinto fault is more active than neighboring major faults, and geologic evidence suggests that the Southern San Andreas fault has been the major plate boundary fault in southern California. Topographic data with 3-4 cm resolution using structure from motion from

  19. Plate Boundary Observatory Strainmeter Recordings of The M6.0 August 24, 2014 South Napa Earthquake

    Science.gov (United States)

    Hodgkinson, Kathleen; Mencin, David; Phillips, David; Mattioli, Glen; Meertens, Charles

    2015-04-01

    The 2014 Mw6.0 South Napa earthquake nucleated at 11 km depth near the West Napa fault, one of a complex system of sub-parallel major right lateral faults north of San Francisco that together accommodate much of the relative motion between the Pacific and North American tectonic plates. The South Napa event was the largest to have shaken the San Francisco Bay Area (SFBA) in almost 25 years. A major goal of the NSF-funded EarthScope Plate Boundary Observatory (PBO), installed and maintained by UNAVCO, was to enable researchers to study the interaction between the faults that form a plate boundary zone, and in particular, to investigate the role that aseismic transients contribute to strain accumulation and release. To realize this goal, PBO includes borehole tensor strainmeters (BSMs) installed in several targeted regions, including on to the north and east of San Francisco. Two PBO BSMs have been operating in the SFBA since 2008: B057, north of San Francisco and 30 km from the epicenter, and B054, 3 km from the Hayward Fault and 40 km from the epicenter. We find the coseismic strains recorded by B057 are close to those predicted using elastic half-space dislocation theory and the seismically determined focal mechanism, while a more complicated variable slip model may be required for observations from B054. Months after the event, B057 continued to record a significant postseismic signal. In this presentation we document the coseismic signals recorded by the PBO BSMs and characterize the temporal behavior of the postseismic signal at B057. The PBO network includes over 1100 GPS, 75 BSMs, 79 seismometers and arrays of tiltmeters, pore pressure sensors and meteorological instrumentation. UNAVCO generates an Earthscope Level 2 processed strain time-series combined into areal and shear strains for the PBO BSM network; the raw data are available from the IRIS DMC in mSEED format. For events of interest, such as the South Napa earthquake, UNAVCO generates a 1-sps

  20. BUOYANCY INSTABILITY IN THE NATURAL CONVECTION BOUNDARY LAYER AROUND A VERTICAL HEATED FLAT PLATE

    Institute of Scientific and Technical Information of China (English)

    颜大椿; 张汉勋

    2002-01-01

    A systematic research on the buoyancy instability in the natural convection boundary layer was conducted, including the basic characteristics such as its spectral components, wave length and velocity, the location of its critical layer,and amplitude distributions of the triple independent eigenmodes with the linear instability theory, the growth rates of its temperature and velocity fluctuations and the corresponding neutral curves for the buoyancy eigenmode were also obtained.Results indicated that the neutral curve of the velocity fluctuation had a nose shape consistent with that obtained in the numerical calculation, but for the temperature fluctuation, a ring-like region could be measured at a lower Grashof number before the nose-shaped main portion of the neutral curve.

  1. Direct numerical simulation methods of hypersonic flat-plate boundary layer in thermally perfect gas

    Science.gov (United States)

    Jia, WenLi; Cao, Wei

    2014-01-01

    High-temperature effects alter the physical and transport properties of air such as vibrational excitation in a thermally perfect gas, and this factor should be considered in order to compute the flow field correctly. Herein, for the thermally perfect gas, a simple method of direct numerical simulation on flat-plat boundary layer is put forward, using the equivalent specific heat ratio instead of constant specific heat ratio in the N-S equations and flux splitting form of a calorically perfect gas. The results calculated by the new method are consistent with that by solving the N-S equations of a thermally perfect gas directly. The mean flow has the similarity, and consistent to the corresponding Blasius solution, which confirms that satisfactory results can be obtained basing on the Blasius solution as the mean flow directly in stability analysis. The amplitude growth curve of small disturbance is introduced at the inlet by using direct numerical simulation, which is consistent with that obtained by linear stability theory. It verified that the equation established and the simulation method is correct.

  2. Drag and Lift Force Acting on a Rotational Spherical Particle in a Logarithmic Boundary Flow

    Institute of Scientific and Technical Information of China (English)

    XU Wei-jiang; CHE De-fu; XU Tong-mo

    2006-01-01

    The drag and lift forces acting on a rotational spherical particle in a logarithmic boundary flow are numerically studied. The effects of the drag velocity and rotational speed of the sphere on the drag force are examined for the particle Reynolds number from 50 to 300 and for the dimensionless rotational angular speed of 0≤Ω≤1.0. The influence of dimensionless roughness height z0of the wall is also evaluated for z0≤10. The results show that the drag forces on a sphere both in a logarithmic flow and in a uniform unsheared flow increase with the increase of the drag velocity. For 50≤Rep≤300, the drag coefficient (-C)D increases with decreased roughness height z0. The time-averaged drag coefficient is also significantly affected by rotational speed of the sphere and roughness height z0 . The lift coefficient -CL increases with increased rotational speed and decreases with increased roughness height.

  3. An implementation of the direct-forcing immersed boundary method using GPU power

    Directory of Open Access Journals (Sweden)

    Bulent Tutkun

    2017-01-01

    Full Text Available A graphics processing unit (GPU is utilized to apply the direct-forcing immersed boundary method. The code running on the GPU is generated with the help of the Compute Unified Device Architecture (CUDA. The first and second spatial derivatives of the incompressible Navier-Stokes equations are discretized by the sixth-order central compact finite-difference schemes. Two flow fields are simulated. The first test case is the simulated flow around a square cylinder, with the results providing good estimations of the wake region mechanics and vortex shedding. The second test case is the simulated flow around a circular cylinder. This case was selected to better understand the effects of sharp corners on the force coefficients. It was observed that the estimation of the force coefficients did not result in any troubles in the case of a circular cylinder. Additionally, the performance values obtained for the calculation time for the solution of the Poisson equation are compared with the values for other CPUs and GPUs from the literature. Consequently, approximately 3× and 20× speedups are achieved in comparison with GPU (using CUSP library and CPU, respectively. CUSP is an open-source library for sparse linear algebra and graph computations on CUDA.

  4. Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

    NARCIS (Netherlands)

    Sissingh, W.

    2008-01-01

    This paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence bou

  5. Punctuated Neogene tectonics and stratigraphy of the African-Iberian plate-boundary zone: concurrent development of Betic-Rif basins (southern Spain, northern Morocco)

    NARCIS (Netherlands)

    Sissingh, W.

    2008-01-01

    This paper integrates the sequence stratigraphic and tectonic data related to the Neogene geodynamic and palaeogeographic development of the African-Iberian plate boundary zone between Spain and Morocco. Though the dating of individual tectonostratigraphic sequences and their delimiting sequence bou

  6. The northern Caribbean plate boundary in the Jamaica Passage: Structure and seismic stratigraphy

    Science.gov (United States)

    Corbeau, J.; Rolandone, F.; Leroy, S.; Mercier de Lépinay, B.; Meyer, B.; Ellouz-Zimmermann, N.; Momplaisir, R.

    2016-04-01

    Multibeam bathymetry data and multichannel seismic reflection profiles have been collected at the end of 2012 along the Enriquillo-Plantain-Garden Fault Zone (EPGFZ) in the Jamaica Passage, between Jamaica and Hispaniola. Analysis of the data set reveals the tectonic evolution and the stratigraphic complexity of the northern Caribbean boundary. Stratigraphic correlations with previous marine and on land studies are proposed to place the identified seismic sequences in their regional tectonic history. Two distinct crustal domains are interpreted. Typical stratigraphic sequences for the rifted blocks of the Eastern Cayman Trough margin are identified in five basins of the Jamaica Passage, highlighting the eastward limit of the Cayman Trough margin. These inherited basins are deformed and folded during a first phase of compression that could correspond to the regional tectonic rearrangement recorded in the early Miocene (about 20 Ma). A distinct crustal domain that we propose to relate to the Carib Beds (Caribbean typical reflectors A″, B″ and V) is identified in the southern part of the Jamaica Passage, indicating that the Caribbean Large Igneous Province could extend up to the extreme northeast part of the Lower Nicaragua Rise. The left-lateral EPGFZ currently cuts across two pre-existing basins, the Morant and Matley basins. During the activity of the EPGFZ, these basins are deformed and folded indicating a second phase of compression. In contrast, the Navassa basin, located in the middle of the Jamaica Passage, results from the strike-slip motion of the EPGFZ and is interpreted as an asymmetrical basin bordered by the EPGFZ only on its northern side.

  7. Integration of the Plate Boundary Observatory and Existing GPS Networks in Southern California: A Multi Use Geodetic Network

    Science.gov (United States)

    Walls, C.; Blume, F.; Meertens, C.; Arnitz, E.; Lawrence, S.; Miller, S.; Bradley, W.; Jackson, M.; Feaux, K.

    2007-12-01

    The ultra-stable GPS monument design developed by Southern California Geodetic Network (SCIGN) in the late 1990s demonstrates sub-millimeter errors on long time series where there are a high percentage of observations and low multipath. Following SCIGN, other networks such as PANGA and BARGEN have adopted the monument design for both deep drilled braced monuments (DDBM = 5 legs grouted 10.7 meters into bedrock/stratigraphy) and short drilled braced monuments (SDBM = 4 legs epoxied 2 meters into bedrock). A Plate Boundary Observatory (PBO) GPS station consists of a "SCIGN" style monument and state of the art NetRS receiver and IP based communications. Between the years 2003-2008 875 permanent PBO GPS stations are being built throughout the United States. Concomitant with construction of the PBO the majority of pre-existing GPS stations that meet stability specifications are being upgraded with Trimble NetRS and IP based communications to PBO standards under the EarthScope PBO Nucleus project. In 2008, with completed construction of the Plate Boundary Observatory, more than 1100 GPS stations will share common design specifications and have identical receivers with common communications making it the most homogenous geodetic network in the World. Of the 875 total Plate Boundary Observatory GPS stations, 211 proposed sites are distributed throughout the Southern California region. As of August 2007 the production status is: 174 stations built (81 short braced monuments, 93 deep drilled braced monuments), 181 permits signed, 211 permits submitted and 211 station reconnaissance reports. The balance of 37 stations (19 SDBM and 18 DDBM) will be built over the next year from Long Valley to the Mexico border in order of priority as recommended by the PBO Transform, Extension and Magmatic working groups. Fifteen second data is archived for each station and 1 Hz as well as 5 Hz data is buffered to be triggered for download in the event of an earthquake. Communications

  8. Casimir force between a half-space and a plate of finite thickness

    Science.gov (United States)

    Høye, Johan S.; Brevik, Iver

    2016-05-01

    Zero-frequency Casimir theory is analyzed from different viewpoints, with the aim of obtaining further insight into the delicate Drude-plasma issue that turns up when one considers thermal corrections to the Casimir force. The problem is essentially that the plasma model, physically inferior in comparison to the Drude model since it leaves out dissipation in the material, apparently gives the best results when comparing with recent experiments. Our geometric setup is quite conventional, namely, a dielectric plate separated from a dielectric half-space by a vacuum gap, both media being made of the same material. Our investigation is divided into the following categories: (1) Making use of the statistical-mechanical method developed by J. S. Høye and I. Brevik [Physica A (Amsterdam, Neth.) 259, 165 (1998), 10.1016/S0378-4371(98)00249-0], implying that the quantized electromagnetic field is replaced by interaction between dipole moments oscillating in harmonic potentials, we first verify that the Casimir force is in agreement with the Drude prediction. No use of Fresnel's reflection coefficients is made at this stage. (2) Then turning to the field-theoretic description implying use of the reflection coefficients, we derive results in agreement with the forgoing when first setting the frequency equal to zero, before letting the permittivity become large. With the plasma relation the reflection coefficient for TE zero-frequency modes depends on the component of the wave vector parallel to the surfaces and lies between 0 and 1. This contradicts basic electrostatic theory. (3) Turning to high-permeability magnetic materials, the TE zero-frequency mode describes the static magnetic field in the same way the TM zero-frequency modes describe the static electric fields in electrostatics. With the plasma model magnetic fields, except for a small part, cannot pass through metals; that is, metals effectively become superconductors. However, recent experimental results clearly

  9. FINITE ELEMENT ANALYSIS OF A VERTICAL RECTANGULAR PLATE COUPLED WITH AN UNBOUNDED FLUID DOMAIN ON ONE SIDE USING A TRUNCATED FAR BOUNDARY

    Institute of Scientific and Technical Information of China (English)

    PANI P. K.; BHATTACHARYYA S. K.

    2009-01-01

    The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin's theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-b method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.

  10. Far-Field Deformation Resulting from Rheologic Differences Interacting with Tectonic Stresses: An Example from the Pacific/Australian Plate Boundary in Southern New Zealand

    Directory of Open Access Journals (Sweden)

    Phaedra Upton

    2014-07-01

    Full Text Available The Miocene in Southern New Zealand was dominated by strike-slip tectonics. Stratigraphic evidence from this time attests to two zones of subsidence in the south: (a a middle Cenozoic pull-apart basin and (b a regionally extensive subsiding lake complex, which developed east and distal to the developing plate boundary structure. The lake overlay a block of crust with a significantly weak mid-crustal section and we pose the question: can rheological transitions at an angle to a plate boundary produce distal subsidence and/or uplift? We use stratigraphic, structural and geophysical observations from Southern New Zealand to constrain three-dimensional numerical models for a variety of boundary conditions and rheological scenarios. We show that coincident subsidence and uplift can result from purely strike-slip boundary conditions interacting with a transition from strong to weak to strong mid-crustal rheology. The resulting pattern of vertical displacement is a function of the symmetry or asymmetry of the boundary conditions and the extent and orientation of the rheological transitions. For the Southern New Zealand case study, subsidence rates of ~0.1 mm/yr are predicted for a relative plate motion of 25 mm/yr, leading to ~500 m of subsidence over a 5 Ma time period, comparable to the thickness of preserved lacustrine sediments.

  11. Optimal decay rate of vibrating beam equations controlled by combined boundary feedback forces

    Institute of Scientific and Technical Information of China (English)

    于景元; 李胜家; 王耀庭; 粱展东

    1999-01-01

    The optimal decay rate problem is considered for boundary control system modeling by a flexible structure consisting of a Eular-Bernoulli beam. Controls are a bending moment in proportion to angular velocity and a shear force in proportion to velocity. A sensitivity asymptotic analysis of the system’ s eigenvalues and eigenfunctions is set up. It is proved that, for every 00, y(0)=Y0, Y0=(Y1,Y2)T ∈V×H form a Riesz basis of V×H, and the optimal exponential decay rate can be obtained from the spectrum of the system.

  12. Boundary slip study on hydrophilic, hydrophobic, and superhydrophobic surfaces with dynamic atomic force microscopy.

    Science.gov (United States)

    Bhushan, Bharat; Wang, Yuliang; Maali, Abdelhamid

    2009-07-21

    Slip length has been measured using the dynamic atomic force microscopy (AFM) method. Unlike the contact AFM method, the sample surface approaches an oscillating sphere with a very low velocity in the dynamic AFM method. During this process, the amplitude and phase shift data are recorded to calculate the hydrodynamic damping coefficient, which is then used to obtain slip length. In this study, a glass sphere with a large radius was glued to the end of an AFM cantilever to measure the slip length on rough surfaces. Experimental results for hydrophilic, hydrophobic, and superhydrophobic surfaces show that the hydrodynamic damping coefficient decreases from the hydrophilic surface to the hydrophobic surface and from the hydrophobic one to the superhydrophobic one. The slip lengths obtained on the hydrophobic and superhydrophobic surfaces are 43 and 236 nm, respectively, which indicates increasing boundary slip from the hydrophobic surface to the superhydrophobic one.

  13. Relocating Seismicity on the Arctic Plate Boundary Using Teleseismic and Regional Phases and a Bayesian Multiple Event Locator

    Science.gov (United States)

    Gibbons, Steven J.; Dahl-Jensen, Trine; Kværna, Tormod; Larsen, Tine B.; Paulsen, Berit; Voss, Peter

    2016-04-01

    The tectonophysics of plate boundaries are illuminated by the pattern of seismicity - and the ability to locate seismic events accurately depends upon the number and quality of observations, the distribution of recording stations, and how well the traveltimes of seismic phases are modelled. The boundary between the Eurasian and North American plates between 70 and 84 degrees North hosts large seismic events which are well recorded teleseismically and many more 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 15 years, 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 quiet and accessible sites, and the expense and difficult logistics of deploying and maintaining stations. New deployments and upgrades to stations on Greenland, Svalbard, and the islands 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 catalog of over 1000 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. The Bayesloc program, a Bayesian hierarchical multiple event location algorithm, has been used to relocate the full set of events iteratively and this has resulted in a significant reduction in the spread in hypocenter estimates for both large and small events. Whereas single event location algorithms minimize the vector of time residuals on an event-by-event basis, Bayesloc favours the hypocenters which

  14. A plate boundary earthquake record from a wetland adjacent to the Alpine fault in New Zealand refines hazard estimates

    Science.gov (United States)

    Cochran, U. A.; Clark, K. J.; Howarth, J. D.; Biasi, G. P.; Langridge, R. M.; Villamor, P.; Berryman, K. R.; Vandergoes, M. J.

    2017-04-01

    Discovery and investigation of millennial-scale geological records of past large earthquakes improve understanding of earthquake frequency, recurrence behaviour, and likelihood of future rupture of major active faults. Here we present a ∼2000 year-long, seven-event earthquake record from John O'Groats wetland adjacent to the Alpine fault in New Zealand, one of the most active strike-slip faults in the world. We linked this record with the 7000 year-long, 22-event earthquake record from Hokuri Creek (20 km along strike to the north) to refine estimates of earthquake frequency and recurrence behaviour for the South Westland section of the plate boundary fault. Eight cores from John O'Groats wetland revealed a sequence that alternated between organic-dominated and clastic-dominated sediment packages. Transitions from a thick organic unit to a thick clastic unit that were sharp, involved a significant change in depositional environment, and were basin-wide, were interpreted as evidence of past surface-rupturing earthquakes. Radiocarbon dates of short-lived organic fractions either side of these transitions were modelled to provide estimates for earthquake ages. Of the seven events recognised at the John O'Groats site, three post-date the most recent event at Hokuri Creek, two match events at Hokuri Creek, and two events at John O'Groats occurred in a long interval during which the Hokuri Creek site may not have been recording earthquakes clearly. The preferred John O'Groats-Hokuri Creek earthquake record consists of 27 events since ∼6000 BC for which we calculate a mean recurrence interval of 291 ± 23 years, shorter than previously estimated for the South Westland section of the fault and shorter than the current interseismic period. The revised 50-year conditional probability of a surface-rupturing earthquake on this fault section is 29%. The coefficient of variation is estimated at 0.41. We suggest the low recurrence variability is likely to be a feature of

  15. Joint inversion of local, regional and teleseismic data for crustal thickness in the Eurasia-Africa plate boundary region

    Science.gov (United States)

    Marone, Federica; van der Meijde, Mark; van der Lee, Suzan; Giardini, Domenico

    2003-08-01

    A new map for the Moho discontinuity (EAM02) in the Eurasia-Africa plate boundary region is presented. Reliable results have also been obtained for the southern and eastern Mediterranean Basin, the northern African coasts and the eastern Atlantic Ocean, regions only occasionally considered in studies on the Mediterranean region. The Moho topography model is derived from two independent sets of constraints. Information contained in the fundamental and higher-mode Rayleigh waves obtained from waveform modelling is used to constrain the Moho depth between estimates of crustal thickness taken from published reflection and refraction surveys, gravity studies and receiver function analysis. Strong lateral variations in the Moho topography have been observed in the Mediterranean Sea, confirming the complex evolution of this plate boundary region. In the west, the Moho discontinuity has been found at 15-20 km depth, suggesting extended and, at least in some locations, oceanic crust, while in the east the crust is on average 25-30 km thick. There it is interpreted either as Mesozoic oceanic or thinned Precambrian continental crust covered by thick sedimentary deposits. Standard continental crust (30-35 km) is observed along the eastern part of the northern African coast, while to the west a rapid change from a relatively deep Moho (down to 42 km) below the Atlas Mountain Range to the thin crust of the southwestern Mediterranean Sea has been found. The crust beneath the eastern North Atlantic Ocean can be up to 5 km thicker compared with standard oceanic crust (6 km). The crust has been interpreted to be heterogeneous as a consequence of irregular magma supply at the Mid-Atlantic ridge. In addition, serpentinization of the sub-Moho mantle could contribute to the imaging of apparently anomalous thick oceanic crust. In Europe, the presence of crustal roots (>45 km) beneath the major mountain belts has been confirmed, while thin crust (isostatic compensation at 60 km depth

  16. Jet-boundary and Plan-form Corrections for Partial-Span Models with Reflection-Plane, End-Plate, or No End-Plate in a Closed Circular Wind Tunnel

    Science.gov (United States)

    Sivells, James C; Deters, Owen J

    1946-01-01

    A method is presented for determining the jet-boundary and plan-form corrections necessary for application to test data for a partial-span model with a reflection plane, an end plate, or no end plate in a closed circular wind tunnel. Examples are worked out for a partial-span model with each of the three end conditions in the Langley 19-foot pressure tunnel and the corrections are applied to measured values of lift, drag, pitching-moment, rolling-moment, and yawing-moment coefficients.

  17. The INGV National Earthquake Centre research infrastructure to study the plate boundary deformation in the Central Mediterranean

    Science.gov (United States)

    Selvaggi, Giulio; Mazza, Salvatore; Delladio, Alberto; Cecere, Gianpaolo; Devoti, Roberto

    2010-05-01

    To understand the complex kinematics within the plate boundary zone between Africa and Eurasia in the central Mediterranean, INGV installed a monitoring system based on broad-band seismometers, CGPS and strong motion sensors, most of them co-located in the same site. Established since early '80 with some tens of short period seismometers and analogue transmission, now the monitoring system consists of more than 200 real time broad-band seismometers, 140 CGPS and about 80 strong motions connected to different centres of acquisition. A dedicated disaster recovery guarantees continuity of acquisition and data sharing among centres. Beside essential services connected to Italian Civil Protection agency and basic research, we believe that our network represents an important reality in the framework of the EPOS infrastructure and we strongly support the idea of an European research approach to data sharing among the scientific community. In the presentation we will show the network, from the sites to the acquisition centres, and the level of the seismic and geodetic products and the primary scientific targets addressed when designing the networks.

  18. Progressive migration of slab break-off along the southern Tyrrhenian plate boundary: Constraints for the present day kinematics

    Science.gov (United States)

    Chiarabba, Claudio; Palano, Mimmo

    2017-04-01

    The Ionian subduction in the central Mediterranean, just 200 km wide, is one of the narrowest in the world. Its evolution has involved a progressive disruption of the subducting slab, contemporaneous to the retreat and step-wise opening of back-arc basins. In this study, we analyse velocity anomalies of the upper mantle, together with the most comprehensive set of earthquake locations and kinematic indicators available for Italy, to reconstruct the geodynamics and tectonic evolution of the Ionian subduction system. Along the Sicilian boundary, we identify an eastward migration of the slab edge with detachment of the Ionian oceanic lithosphere. We hypothesize that the progressive detachment of the slab took place along lithospheric transform faults of the Neo-Tethys Ocean. Among the main active kinematic elements of the Ionian accretionary wedge, we suggest that a ∼400-km-long and highly segmented shear zone formed by the Aeolian-Tindari-Letojanni fault system and the Ionian fault represents the surface expression of such a lithospheric tearing. The present day convergence between the Eurasian and African plates is accommodated both at the frontal thrust of the flexed Hyblean margin in southern Sicily and offshore along the Tyrrhenian Sea. Lithospheric bending favors the wedging of the mantle underneath northern Sicily, while magmatic fluids are channeled along slab tears.

  19. A boundary-integral model for drop deformation between two parallel plates with non-unit viscosity ratio drops

    Science.gov (United States)

    Janssen, P. J. A.; Anderson, P. D.

    2008-10-01

    A boundary-integral method is presented for drop deformation between two parallel walls for non-unit viscosity ratio systems. To account for the effect of the walls the Green's functions are modified and all terms for the double-layer potential are derived. The full three-dimensional implementation is validated, and the model is shown to be accurate and consistent. The method is applied to study drop deformation in shear flow. An excellent match with small-deformation theory is found at low capillary numbers, and our results match with other BIM simulations for pressure-driven flows. For shear flow with moderate capillary numbers, we see that the behavior of a low-viscosity drop is similar to that of drop with a viscosity ratio of unity. High-viscosity drops, on the other hand, are prevented from rotating in shear flow, which results in a larger deformation, but less overshoot in the drop axes is observed. In contrast with unconfined flow, high-viscosity drops can be broken in shear flow between parallel plates; for low-viscosity drops the critical capillary number is higher in confined situations.

  20. Seismic heating signatures in the Japan Trench subduction plate-boundary fault zone: evidence from a preliminary rock magnetic `geothermometer'

    Science.gov (United States)

    Yang, Tao; Dekkers, Mark J.; Zhang, Bo

    2016-04-01

    Frictional heating during earthquake rupture reveals important information on earthquake mechanisms and energy dissipation. The amount of annealing varies widely and is, as yet, poorly constrained. Here we use magnetic susceptibility versus temperature measurements during cycling to increasingly elevated temperatures to constrain the maximum temperature a slip zone has experienced. The case study comprises sheared clay cored from the Japan Trench subduction plate-boundary fault zone (décollement), which accommodated the large slip of the 2011 Mw 9.0 Tohoku-oki earthquake. The décollement was cored during the Integrated Ocean Drilling Program (IODP) Expedition 343, the Japan Trench Fast Drilling Project (JFAST). Heating signatures with estimated maximum temperatures ranging from ˜300 to over 500 °C are determined close to the multiple slip surfaces within the décollement. Since it is impossible to tie a specific slip surface to a certain earthquake, thermal evidence for the cumulative effect of several earthquakes is unveiled. This as yet preliminary rock magnetic `geothermometer' would be a useful tool to detect seismic heating along faults that experienced medium temperature rise, a range which is difficult to assess with other approaches.

  1. Crustal Structure of the Caribbean-South American Diffuse Plate Boundary: Subduction Zone Migration and Polarity Reversal Along BOLIVAR Profile 64W

    Science.gov (United States)

    Clark, S. A.; Levander, A.; Magnani, M.; Zelt, C. A.; Sawyer, D. S.; Ave Lallemant, H. G.

    2005-12-01

    The BOLIVAR (Broadband Ocean-Land Investigation of Venezuela and the Antilles arc Region) project is an NSF funded, collaborative seismic experiment in the southeast Caribbean region. The purpose of the project is to understand the diffuse plate boundary created by the oblique collision between the Caribbean and South American plates. Profile 64W of the BOLIVAR experiment, a 450 km-long, N-S transect onshore and offshore Venezuela located at ~64°W longitude, images the deep crustal structures formed by this collision. The active source components of profile 64W include 300 km of MCS reflection data, 33 coincident OBSs, and 344 land seismic stations which recorded 7500 offshore airgun shots and 2 explosive land shots. Results from the reflection and refraction seismic data along 64W show complex crustal structure across the entire span of the diffuse plate boundary. The onshore portion of 64W crosses the fold and thrust belt of the Serrania del Interior, which formed at ~16 Ma by collision of the Caribbean forearc with the northern South American passive margin. Underlying the Serrania del Interior is a south-vergent, remnant Lesser Antillean subduction zone. As this Lesser Antilles subduction impinged on continental crust, it caused a polarity reversal and jump offshore to the north. Convergence was initially localized in the closure and inversion of the Grenada Basin. However, subduction could not develop because of the ~20-km-thick crust of the Aves Ridge; instead, north-vergent subduction initiated further to the north, where ~12-km-thick Caribbean oceanic crust of the Venezuela Basin began to subduct beneath the Aves Ridge in the Pliocene (~4 Ma) and appears to continue subducting today. Between the remnant subduction zone and the modern one, the El Pilar and Coche dextral strike-slip faults accommodate most of the transform motion of the plate boundary. From the Serrania del Interior to the Aves Ridge, ~260 km of accreted orogenic float comprises the diffuse

  2. The forced sound transmission of finite ribbed plates, investigating the influence of point connections and periodicity

    DEFF Research Database (Denmark)

    Brunskog, Jonas

    2015-01-01

    Many engineering structures consist of plates being stiffened by ribs. The ribs can be connected to the plate in a line connection (welded or glued) or in point connections (screwed). It is well known that the rib stiffeners can significantly change the vibration field and the radiation behavior...... been derived, using a variational technique based on integral-differential equations of the fluid loaded plate. In this way an optimal solution is derived, using a very simple initial guess of the vibration field. The finite plate is assumed being mounted in a rigid baffle. The approach is based...... the model. The influence of point versus line connections, as well as periodicity effects, is investigated....

  3. The October 28, 2012 Mw 7.8 Haida Gwaii underthrusting earthquake and tsunami: Slip partitioning along the Queen Charlotte Fault transpressional plate boundary

    Science.gov (United States)

    Lay, Thorne; Ye, Lingling; Kanamori, Hiroo; Yamazaki, Yoshiki; Cheung, Kwok Fai; Kwong, Kevin; Koper, Keith D.

    2013-08-01

    The Pacific/North American plate boundary is undergoing predominantly right-lateral strike-slip motion along the Queen Charlotte and Fairweather transform faults. The Queen Charlotte Fault (QCF) hosted the largest historical earthquake in Canada, the 1949 MS 8.1 strike-slip earthquake, which ruptured from offshore northern Haida Gwaii several hundred kilometers northwestward. On January 5, 2013 an Mw 7.5 strike-slip faulting event occurred near the northern end of the 1949 rupture zone. Along central and southern Haida Gwaii the relative plate motion has ∼20% oblique convergence across the left-stepping plate boundary. There had been uncertainty in how the compressional component of plate motion is accommodated. The October 28, 2012 Mw 7.8 Haida Gwaii earthquake involved slightly (∼20°) oblique thrust faulting on a shallow (∼18.5°) northeast-dipping fault plane with strike (∼320°) parallel to the QCF, consistent with prior inferences of Pacific Plate underthrusting beneath Haida Gwaii. The rupture extended to shallow depth offshore of Moresby Island beneath a 25-30 km wide terrace of sediments that has accumulated in a wedge seaward of the QCF. The shallow thrusting caused seafloor uplift that generated substantial localized tsunami run-up and a modest far-field tsunami that spread across the northern Pacific, prompting a tsunami warning, beach closure, and coastal evacuation in Hawaii, although ultimately tide gauges showed less than 0.8 m of water level increase. The mainshock rupture appears to have spread with a ∼2.3 km/s rupture velocity over a length of ∼150 km, with slip averaging 3.3 m concentrated beneath the sedimentary wedge. The event was followed by a substantial aftershock sequence, in which almost all of the larger events involve distributed intraplate normal faulting extending ∼50 km oceanward from the QCF. The highly oblique slip partitioning in southern Haida Gwaii is distinctive in that the local plate boundary-parallel motion on

  4. Investigating crustal deformation associated with the North America-Pacific plate boundary in southern California with GPS geodesy

    Science.gov (United States)

    Spinler, Joshua C.

    The three largest earthquakes in the last 25 years in southern California occurred on faults located adjacent to the southern San Andreas fault, with the M7.3 1992 Landers and M7.1 1999 Hector Mine earthquakes occurring in the eastern California shear zone (ECSZ) in the Mojave Desert, and the M7.2 2010 El Mayor-Cucapah earthquake occurring along the Laguna Salada fault in northern Baja California, Mexico. The locations of these events near to but not along the southern San Andreas fault (SSAF) is unusual in that the last major event on the SSAF occurred more than 300 years ago, with an estimated recurrence interval of 215 +/- 25 years. The focus of this dissertation is to address the present-day deformation field along the North America-Pacific plate boundary in southern California and northern Baja California, through the analysis of GPS data, and elastic block and viscoelastic earthquake models to determine fault slip rates and rheological properties of the lithosphere in the plate boundary zone. We accomplish this in three separate studies. The first study looks at how strain is partitioned northwards along-strike from the southern San Andreas fault near the Salton Sea. We find that estimates for slip-rates on the southern San Andreas decrease from ~23 mm/yr in the south to ~8 mm/yr as the fault passes through San Gorgonio Pass to the northwest, while ~13-18 mm/yr of slip is partitioned onto NW-SE trending faults of the ECSZ where the Landers and Hector Mine earthquakes occurred. This speaks directly to San Andreas earthquake hazards, as a reduction in the slip rate would require greater time between events to build up enough slip deficit in order to generate a large magnitude earthquake. The second study focuses on inferring the rheological structure beneath the Salton Trough region. This is accomplished through analysis of postseismic deformation observed using a set of the GPS data collected before and after the 2010 El Mayor-Cucapah earthquake. By

  5. Forced convection heat transfer of Couette-Poiseuille flow of nonlinear viscoelastic fluids between parallel plates

    Energy Technology Data Exchange (ETDEWEB)

    Hashemabadi, S.H. [Iran Univ. of Science and Technology, Dept. of Chemical Engineering, Tehran (Iran); Etemad, S.Gh. [Isfahan Univ. of Technology, Dept. of Chemical Engineering, Isfahan (Israel); Thibault, J. [Ottawa Univ., Dept. of Chemical Engineering, Ottawa, ON (Canada)

    2004-08-01

    Heat transfer to viscoelastic fluids is frequently encountered in various industrial processing. In this investigation an analytical solution was obtained to predict the fully developed, steady and laminar heat transfer of viscoelastic fluids between parallel plates. One of the plates was stationary and was subjected to a constant heat flux. The other plate moved with constant velocity and was insulated. The simplified Phan-Thien-Tanner (SPTT) model, believed to be a more realistic model for viscoelastic fluids, was used to represent the rheological behavior of the fluid. The energy equation was solved for a wide range of Brinkman number, dimensionless viscoelastic group, and dimensionless pressure drop. Results highlight the strong effects of these parameters on the heat transfer rate. (Author)

  6. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    Science.gov (United States)

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter.

  7. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    Directory of Open Access Journals (Sweden)

    Meraj Mustafa

    Full Text Available The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter.

  8. Monitoring the terrestrial water cycle with reflected GPS signals recorded by the Plate Boundary Observatory Network (Invited)

    Science.gov (United States)

    Small, E. E.; Larson, K. M.; Braun, J.; Chew, C. C.; McCreight, J. L.

    2013-12-01

    Data from NSF's EarthScope Plate Boundary Observatory (PBO), and similar GPS networks worldwide, can be used to monitor the terrestrial water cycle. GPS satellites transmit L-band microwave signals, which are strongly influenced by water at the surface of the Earth. GPS signals take two different paths: (1) the 'direct' signal travels from the satellite to the antenna; (2) the 'reflected' signal interacts with the Earth's surface before travelling to the antenna. The direct signal is used by geophysicists to measure the position of the antenna. By analyzing these GPS data over multiple years, the motion of the site can be estimated. The effects of reflected signals are generally ignored by geophysicists because they are small. This is not happenstance, as significant effort has been made to design and deploy a GPS antenna that suppresses ground reflections. Our group has developed a new remote sensing technique to retrieve terrestrial water cycle variables from GPS data. We extract the water cycle products from signal strength data that measures the interference between the direct and reflected GPS signals. The sensing footprint is intermediate in scale between in situ observations and most remote sensing measurements. Snow depth, soil moisture, and an index of vegetation water content are estimated from data collected at over 400 PBO sites. The products are updated daily and are available online. Validation studies show that retrieved products are of sufficient quality to be used in a variety of applications. In order to improve the resolution of GPS water cycle products, we are also developing a new sensor especially designed to measure reflected GPS signals. This will yield a more sensitive instrument that costs an order of magnitude less than existing geodetic-quality GPS systems. Such a technology would have broad applications in both research and agricultural settings.

  9. PBO H2O: Monitoring the Terrestrial Water Cycle with reflected GPS signals recorded by the Plate Boundary Observatory Network

    Science.gov (United States)

    Small, E. E.; Fairfax, E. J.; Chew, C. C.; Larson, K. M.

    2015-12-01

    Data from NSF's EarthScope Plate Boundary Observatory (PBO), and similar GPS networks worldwide, can be used to monitor the terrestrial water cycle. GPS satellites transmit L-band microwave signals, which are strongly influenced by water at the surface of the Earth. GPS signals take two different paths: (1) the "direct" signal travels from the satellite to the antenna; (2) the "reflected" signal interacts with the Earth's surface before travelling to the antenna. The direct signal is used by geophysicists to measure the position of the antenna. By analyzing these GPS data over multiple years, the motion of the site can be estimated. The effects of reflected signals are generally ignored by geophysicists because they are small. This is not happenstance, as significant effort has been made to design and deploy a GPS antenna that suppresses ground reflections. Our group has developed a remote sensing technique to retrieve terrestrial water cycle variables from GPS data. We extract the water cycle products from signal strength data that measures the interference between the direct and reflected GPS signals. The sensing footprint is intermediate in scale between in situ observations and most remote sensing measurements. Snow depth, snow water equivalent (SWE), near surface soil moisture, and an index of vegetation water content are currently estimated from nearly 500 PBO sites. These PBO H2O products are updated daily and are available online (http://xenon.colorado.edu/portal/index.php). Validation studies show that retrieved products are of sufficient quality to be used in a variety of applications. The root mean square error (RMSE) of GPS-based SWE is 2 cm, based on a comparison to snow survey data at nearly 20 GPS sites. The RMSE of near surface volumetric soil moisture is moisture and similar products.

  10. Low-latency high-rate GPS data streams from the EarthScope Plate Boundary Observatory

    Science.gov (United States)

    Anderson, G.; Borsa, A.; Jackson, M.; Stark, K.

    2008-05-01

    Real-time processing of high rate GPS data can give precise (e.g., 5-10 mm for data recorded once per second) recordings of rapid volcanic and seismic deformation. These time series now provide an emerging tool for seismic, volcanic, and tsunami geodesy and early warning applications. UNAVCO, as part of the EarthScope Plate Boundary Observatory project, has developed the UStream system to provide streaming GPS data from some PBO and other UNAVCO-operated GPS stations. UStream is based on the Ntrip standard, a widely used protocol for streaming GNSS data over the Internet. Remote GPS stations provide a stream of BINEX data at 1 sample/sec to an Ntrip server at UNAVCO's Boulder offices, while simultaneously recording data locally in the event of communications failure. Once in Boulder, the data fork into three output streams: BINEX files stored at UNAVCO and streams of data in BINEX and RTCM 2.3 format. These streams flow to an Ntrip broadcaster that distributes data to Ntrip clients, which can be anything from low-latency processing systems to external data archiving systems. Current development efforts are geared toward providing data in RTCM 3.x format. This system is now operating in a public beta test mode, with data available from over 55 PBO and Nucleus GPS stations across the western United States. Data latencies from stations operating on mobile telephone communications are under 1.1 seconds at 95% confidence, and data completeness is typically more than 95% barring transient communications disruptions. Data from the system are available under the terms of the draft UNAVCO streaming data usage policy. For further information, please visit http://rtgps.unavco.org or send e-mail to rtgps@unavco.org.

  11. An application of Global Positioning System data from the Plate Boundary Observatory for deformation monitoring purposes (Invited)

    Science.gov (United States)

    Murray-Moraleda, J. R.; Liu, Z.; Segall, P.

    2009-12-01

    The Plate Boundary Observatory (PBO) represents a major step forward in Global Positioning System (GPS) coverage for the western United States by increasing the spatial density of stations, generating daily position estimates, and providing the infrastructure for high-rate and real-time positioning. In addition to producing vital input for a wide range of crustal deformation studies, PBO significantly expands opportunities for monitoring and event response. This presentation will focus on one such effort. Data from large continuous GPS networks like PBO should be monitored for temporal changes, be they tectonic, volcanic, hydrologic, anthropogenic, or instrumental in origin. Since it is not feasible to review time series by eye on a daily basis, automated approaches are required. Here we apply a Kalman filtering based method, termed the Network Inversion Filter (Segall and Matthews, 1997; McGuire and Segall, 2003), to monitor daily GPS data for deformation-related transient signals. This approach relies on the spatial coherence of signals due to transient sources such as fault slip in order to separate them from spatially-localized time-dependent noise. The dense GPS coverage provided by PBO has augmented pre-existing continuous GPS networks making it now feasible to test this method in California. Results from synthetic tests using the >400 station southern California continuous GPS network configuration demonstrate this approach can extract fault slip signals from data contaminated by plausible noise processes. We will present results using real data from the San Francisco Bay Area and discuss the role and limitations of this methodology in hazard monitoring.

  12. Lateral Casimir forces on parallel plates and concentric cylinders with corugations

    CERN Document Server

    Cavero-Pelaez, Ines; Parashar, Prachi; Shajesh, K V

    2008-01-01

    In this paper we are giving a quantitative description of two different configurations for noncontact gears. We consider the solutions from a perturbative calculation for two semitransparent parallel plates and concentric cylinders both with corrugations on the inner surfaces. In the case of corrugated parallel plates we discuss results from first- and second-order perturbation calculation in the corrugation amplitudes and we will concentrate on the first-order perturbation for the case of the corrugated concentric cylinders (the second order calculation is under study), both for the weak and strong couplings. We compare the perturbative results with the results from the PFA and an exact weak coupling calculation.

  13. Non-contact gears: I. Next-to-leading order contribution to lateral Casimir force between corrugated parallel plates

    CERN Document Server

    Cavero-Pelaez, Ines; Parashar, Prachi; Shajesh, K V

    2008-01-01

    We calculate the lateral Casimir force between corrugated parallel plates, described by $\\delta$-function potentials, interacting through a scalar field, using the multiple scattering formalism. The contributions to the Casimir energy due to uncorrugated parallel plates is treated as a background from the outset. We derive the leading- and next-to-leading-order contribution to the lateral Casimir force for the case when the corrugation amplitudes are small in comparison to corrugation wavelengths. We present explicit results in terms of finite integrals for the case of the Dirichlet limit, and exact results for the weak-coupling limit, for the leading- and next-to-leading-orders. The correction due to the next-to-leading contribution is significant. In the weak coupling limit we calculate the lateral Casimir force exactly in terms of a single integral which we evaluate numerically. Exact results for the case of the weak limit allows us to estimate the error in the perturbative results. We show that the error ...

  14. Effect of Chord Splice Joints on Force Distribution and Deformations in Trusses with Punched Metal Plate Fasteners

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    2007-01-01

    The span of roof trusses with punched metal plate fasteners (nail plates) makes it often necessary to use splice joints in the top and bottom chords. In the finite element models used for design of the trusses these splice joints are normally assumed to be either rotationally stiff or pinned - th...... of splice joints on section forces and displacements are discussed considering the results from finite element calculations for a fink truss. It seems that the guidelines for treating splice joints as rotationally stiff do not necessarily lead to more realistic truss models....... - their real behaviour is semi-rigid. The influence of splice joints on the distribution of member forces and rotations in the splice joints is investigated in this paper. A finite element program, TrussLab, where the splice joints are given semi-rigid properties is used to analyse the effect of splice joints...... if their deformation has no significant effect upon the distribution of member forces according to Eurocode 5. Two simple guidelines for the design and location of splice joints are given in Eurocode 5 for treating the splice joints as rotationally stiff. The reasonability of these guidelines and the influence...

  15. Late 18th to early 19th century sea-level history and inter-seismic behavior along the western Myanmar plate boundary belt recorded by coral microatolls

    Science.gov (United States)

    Liu, Sze-Chieh; Shyu, J. Bruce H.

    2016-04-01

    Along the western Myanmar plate boundary belt, the Indian-Australian plate is subducting obliquely beneath the Burma micro-plate at a rate of about 23 mm/yr. Although information about the 1762 Arakan earthquake, the only major historical event occurred along this plate boundary belt, has been delineated recently from uplifted coastal features, constraints on the inter-seismic behavior of this belt is still very limited, due to the lack of high resolution instrumental records in the area. Therefore, we utilized coral microatolls to analyze relative sea level history, in order to obtain potential information of land-level change along the western coast of Myanmar. Our sample was collected from northwestern Ramree Island, approximately 80 km away from the trench. Previous studies suggest that the coral was uplifted and killed during a local earthquake event in 1848, and recorded relative sea level history of ~80 years prior to that event. Since the highest level of survival (HLS) of coral microatolls is constrained within a few centimeters of the lowest tide level of the area, the patterns of annual growth bands of the coral microatoll in x-radiograph provide us yearly record of relative sea level, and we used U-Th dating technique to constrain the age of the coral. Our results show that this coral microatoll may have recorded the inter-seismic subsidence of northwestern Ramree Island, punctuated by several climatic events that produced die-down records of the coral growth bands. We hope the data obtained from this coral microatoll, combined with previously reported information of the area, will enable us to further understand the seismic behavior of this major plate boundary belt.

  16. Plate tectonics, damage and inheritance.

    Science.gov (United States)

    Bercovici, David; Ricard, Yanick

    2014-04-24

    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates.

  17. Heat and mass transfer for natural convection MHD flow over a permeable moving vertical plate with convective boundary condition in the presence of viscous dissipation

    Science.gov (United States)

    Shateyi, Stanford

    2017-07-01

    The spectral relaxation method is employed to examine natural convective heat and mass transfer, MHD flow over a permeable moving vertical plate with convective boundary condition in the presence of viscous dissipation, thermal radiation and chemical reaction. The governing partial differential equations were transformed into a system of nonlinear ordinary differential equations by using a similarity approach. The pertinent results are then displayed in tabular form and graphically.

  18. Spatially Distributed Forcing for Boundary Layer Separation Control on a Wall Mounted Hump

    Science.gov (United States)

    Borgmann, David; Little, Jesse; Woszidlo, Rene

    2016-11-01

    Numerous successful efforts on controlling flow separation have been demonstrated using spatially distributed actuators. These include both steady and unsteady forcing from discrete locations in the vicinity of separation. Despite this, there are many open questions on the actual flow control mechanism. A canonical hump model is used to investigate these physics in a subsonic wind tunnel. Reynolds number independence is achieved above 0.72 ×106 and testing is performed up to 2.2 ×106. The efficacy of discrete steady jets is studied as a function of spacing, momentum coefficient, velocity ratio and mass flux. Highly-resolved surface pressure data for the controlled flow are compared to an inviscid solution establishing a figure of merit. Results indicate the inviscid limit is reached for a momentum coefficient of 1% with actuator spacing of 0.5% span. A comparison of steady discrete jets with sweeping jets actuators of equivalent cross-sectional area is undertaken. Surface flow visualization and PIV are employed to extract detailed information on the baseline and controlled flow field. This importance of establishing critical baseline features is also discussed with respect to establishing proper boundary conditions for accompanying numerical simulations. Supported by The Boeing Company.

  19. Forced convective heat transfer in boundary layer flow of Sisko fluid over a nonlinear stretching sheet.

    Science.gov (United States)

    Munir, Asif; Shahzad, Azeem; Khan, Masood

    2014-01-01

    The major focus of this article is to analyze the forced convective heat transfer in a steady boundary layer flow of Sisko fluid over a nonlinear stretching sheet. Two cases are studied, namely (i) the sheet with variable temperature (PST case) and (ii) the sheet with variable heat flux (PHF case). The heat transfer aspects are investigated for both integer and non-integer values of the power-law index. The governing partial differential equations are reduced to a system of nonlinear ordinary differential equations using appropriate similarity variables and solved numerically. The numerical results are obtained by the shooting method using adaptive Runge Kutta method with Broyden's method in the domain[Formula: see text]. The numerical results for the temperature field are found to be strongly dependent upon the power-law index, stretching parameter, wall temperature parameter, material parameter of the Sisko fluid and Prandtl number. In addition, the local Nusselt number versus wall temperature parameter is also graphed and tabulated for different values of pertaining parameters. Further, numerical results are validated by comparison with exact solutions as well as previously published results in the literature.

  20. Forced Convective Heat Transfer in Boundary Layer Flow of Sisko Fluid over a Nonlinear Stretching Sheet

    Science.gov (United States)

    Munir, Asif; Shahzad, Azeem; Khan, Masood

    2014-01-01

    The major focus of this article is to analyze the forced convective heat transfer in a steady boundary layer flow of Sisko fluid over a nonlinear stretching sheet. Two cases are studied, namely (i) the sheet with variable temperature (PST case) and (ii) the sheet with variable heat flux (PHF case). The heat transfer aspects are investigated for both integer and non-integer values of the power-law index. The governing partial differential equations are reduced to a system of nonlinear ordinary differential equations using appropriate similarity variables and solved numerically. The numerical results are obtained by the shooting method using adaptive Runge Kutta method with Broyden’s method in the domain. The numerical results for the temperature field are found to be strongly dependent upon the power-law index, stretching parameter, wall temperature parameter, material parameter of the Sisko fluid and Prandtl number. In addition, the local Nusselt number versus wall temperature parameter is also graphed and tabulated for different values of pertaining parameters. Further, numerical results are validated by comparison with exact solutions as well as previously published results in the literature. PMID:24949738

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

    Directory of Open Access Journals (Sweden)

    E.Hemalatha

    2015-09-01

    Full Text Available 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 describe radiative heat transfer as we consider optically thick fluids. The governing boundary layer equations are transformed into a system of ordinary differential equations using similarity transformations, which are then solved numerically by employing fourth order Runge-Kutta method along with shooting technique. The effects of various material parameters on the velocity, temperature and concentration as well as the skin friction coefficient, the Nusselt number, the Sherwood number and the plate surface temperature are illustrated and interpreted in physical terms. A comparison of present results with previously published results shows an excellent agreement.

  2. Experimental investigation of forced-convection in a finned rhombic tube of the flat-plate solar collectors

    DEFF Research Database (Denmark)

    Taherian, Hessam; Yazdanshenas, Eshagh

    2006-01-01

    Due to scarcity of literature on forced-convection heat transfer in a solar collector with rhombic cross-section absorbing tubes, a series of experiments was arranged and conducted to determine heat transfer coefficient. In this study, a typical rhombic cross-section finned tube of flat......-plate collectors used as the test section. Two correlations were proposed for the Nusselt number as a function of the Reynolds number and the Prandtl number based on hydraulic diameter for various heat fluxes. The temperature distribution along the finned tube for the fluid and the wall were also illustrated....

  3. Influence of Damping on the Dynamical Behavior of the Electrostatic Parallel-plate and Torsional Actuators with Intermolecular Forces

    OpenAIRE

    Ya-Pu Zhao; Wen-Hui Lin

    2007-01-01

    The influence of damping on the dynamical behavior of the electrostatic parallel-plate and torsional actuators with the van der Waals (vdW) or Casimir force (torque) is presented. The values of the pull-in parameters and the number of the equilibrium points do not change whether there is damping or not. The ability of equilibrium points is varied with the appearance of damping. One equilibrium point is an unstable saddle with a different damping coefficient, the other equilibrium point is a s...

  4. 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.

  5. Combined radiative and natural or forced convective heat transfer between parallel vertical plates with two-dimensional discrete heat sources

    Energy Technology Data Exchange (ETDEWEB)

    Nickell, T.W.

    1988-01-01

    This study numerically analyzes combined radiative and natural or forced convective heat transfer between vertical parallel plates with two-dimensional discrete heat sources. The numerical method was verified by comparing its results with other published experimental data and the agreement was excellent. It is shown that radiative heat transfer is a significant and useful mode of heat transfer in combination with both natural and forced convection in this situation and cannot be neglected. Radiative heat transfer accounted for 50-60% or more of the total heat transfer in some cases, and usually approximately 30-35% on the top of a discrete heat source. This fact can be used to advantage in the thermal design of electronic circuit boards.

  6. Making precise predictions of the Casimir force between metallic plates via a generalized Kramers-Kronig transform

    CERN Document Server

    Bimonte, Giuseppe

    2010-01-01

    The possibility of making precise predictions for the Casimir force is essential for addressing the striking contradiction that has arisen between the a new large distance Casimir experiment with gold plates, that has been interpreted as being consistent with the so-called Drude prescription and to rule out the plasma prescription, and a series of older precise short distance experiments, which were instead interpreted as being consistent with the plasma prescription and to rule out the Drude one. In a previous paper by the author [Phys. Rev. A {\\bf 81}, 062501 (2010)] it was shown that a precise prediction of the Casimir force is possible in principle by a simple modification of the standard Kramers-Kronig relations, involving suitable analytic window functions, solely on the basis of experimental optical data in the frequency interval where they are available, without using uncontrolled data extrapolations towards zero frequency that are necessary with standard Kramers-Kronig relations. In the present paper...

  7. GENERALIZED VARIATIONAL PRINCIPLESFOR VISCOELASTIC THIN AND THICK PLATES WITH DAMAGE

    Institute of Scientific and Technical Information of China (English)

    ShengDongfa; ChengChangjun

    2004-01-01

    From the constitutive model with generalized force fields for a viscoelastic body with damage, the differential equations of motion for thin and thick plates with damage are derived under arbitrary boundary conditions. The convolution-type functionals for the bending of viscoelastic thin and thick plates with damage are presented, and the corresponding generalized variational principles are given. From these generalized principles, all the basic equations of the displacement and damage variables and initial and boundary conditions can be deduced. As an example, we compare the difference between the dynamical properties of plates with and without damage and consider the effect of damage on the dynamical properties of plates.

  8. A simple and self-consistent geostrophic-force-balance model of the thermohaline circulation with boundary mixing

    Directory of Open Access Journals (Sweden)

    J. Callies

    2011-08-01

    Full Text Available A simple model of the thermohaline circulation (THC is formulated, with the objective to represent explicitly the geostrophic force balance of the basinwide THC. The model comprises advective-diffusive density balances in two meridional-vertical planes located at the eastern and the western walls of a hemispheric sector basin. Boundary mixing constrains vertical motion to lateral boundary layers along these walls. Interior, along-boundary, and zonally integrated meridional flows are in thermal-wind balance. Rossby waves and the absence of interior mixing render isopycnals zonally flat except near the western boundary, constraining meridional flow to the western boundary layer. The model is forced by a prescribed meridional surface density profile.

    This two-plane model reproduces both steady-state density and steady-state THC structures of a primitive-equation model. The solution shows narrow deep sinking at the eastern high latitudes, distributed upwelling at both boundaries, and a western boundary current with poleward surface and equatorward deep flow. The overturning strength has a 2/3-power-law dependence on vertical diffusivity and a 1/3-power-law dependence on the imposed meridional surface density difference. Convective mixing plays an essential role in the two-plane model, ensuring that deep sinking is located at high latitudes. This role of convective mixing is consistent with that in three-dimensional models and marks a~sharp contrast with previous two-dimensional models.

    Overall, the two-plane model reproduces crucial features of the THC as simulated in simple-geometry three-dimensional models. At the same time, the model self-consistently makes quantitative a conceptual picture of the three-dimensional THC that hitherto has been expressed either purely qualitatively or not self-consistently.

  9. A simple and self-consistent geostrophic-force-balance model of the thermohaline circulation with boundary mixing

    Directory of Open Access Journals (Sweden)

    J. Callies

    2012-01-01

    Full Text Available A simple model of the thermohaline circulation (THC is formulated, with the objective to represent explicitly the geostrophic force balance of the basinwide THC. The model comprises advective-diffusive density balances in two meridional-vertical planes located at the eastern and the western walls of a hemispheric sector basin. Boundary mixing constrains vertical motion to lateral boundary layers along these walls. Interior, along-boundary, and zonally integrated meridional flows are in thermal-wind balance. Rossby waves and the absence of interior mixing render isopycnals zonally flat except near the western boundary, constraining meridional flow to the western boundary layer. The model is forced by a prescribed meridional surface density profile.

    This two-plane model reproduces both steady-state density and steady-state THC structures of a primitive-equation model. The solution shows narrow deep sinking at the eastern high latitudes, distributed upwelling at both boundaries, and a western boundary current with poleward surface and equatorward deep flow. The overturning strength has a 2/3-power-law dependence on vertical diffusivity and a 1/3-power-law dependence on the imposed meridional surface density difference. Convective mixing plays an essential role in the two-plane model, ensuring that deep sinking is located at high latitudes. This role of convective mixing is consistent with that in three-dimensional models and marks a sharp contrast with previous two-dimensional models.

    Overall, the two-plane model reproduces crucial features of the THC as simulated in simple-geometry three-dimensional models. At the same time, the model self-consistently makes quantitative a conceptual picture of the three-dimensional THC that hitherto has been expressed either purely qualitatively or not self-consistently.

  10. AN EXACT ANALYSIS OF FORCED THICKNESS-TWIST VIBRATIONS OF MULTI-LAYERED PIEZOELECTRIC PLATES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper deals with the thickness-twist vibration of a multi-layered rectangular piezoelectric plate of crystals of 6 mm symmetry or polarized ceramics. An exact solution is obtained from the three-dimensional equations of linear piezoelectricity. The solution is useful to the understanding and design of composite piezoelectric devices. A piezoelectric resonator, a piezoelectric transformer, and a piezoelectric generator are analyzed as examples.

  11. 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

  12. UNAVCO Enhanced data products for the EarthScope Plate Boundary Observatory, COCONet, and other regional networks

    Science.gov (United States)

    Puskas, C. M.; Phillips, D. A.; Mattioli, G. S.; Meertens, C. M.; Herring, T.; Murray, M. H.; Melbourne, T. I.; Boler, F. M.; Blewitt, G.; Larson, K. M.; Feaux, K.; Braun, J. J.; Small, E. E.

    2012-12-01

    As part of an initiative to improve data services and support new research in the geodetic community, UNAVCO and its partners are expanding our supported data products and releasing new visualization tools. The enhanced data products, primarily associated with the UNAVCO-managed EarthScope Plate Boundary Observatory (PBO) and COCONet project, have open access and are archived at UNAVCO. UNAVCO manages community data services for a range of geodetic systems: GPS, borehole strainmeters, laser strainmeters, tiltmeters, pore pressure sensors, and geodetic imaging (InSAR, LIDAR, and terrestrial laser scanning). As part of the expansion, UNAVCO will incorporate data products submitted or downloaded from outside agencies. We focus here on the GPS products, which will include improved geodetic coverage in the western U.S. and expanded coverage in North America, access to new station quality parameters, information on site hydrologic conditions, and hydrologic loading models. Existing, open-access GPS stations from other networks are being incorporated into current 1112-station PBO processing stream to obtain station position time series and velocities for an additional 500+ stations. The primary data sources will be the Southern California Integrated GPS Network (SCIGN), the Scripps Orbit and Permanent Array Center (SOPAC), and the National Geodetic Survey's Continuously Operating Reference (NGS CORS) network. These additional stations will comprise a backbone network across continental North America to better resolve the surface velocity field in central and eastern U.S. and Canada, regions not presently covered by PBO. The expanded geographic coverage will address possible tectonic signals on a continental scale and will improve resolution of intraplate seismic zones and glacial-isostatic adjustments. The large data set will also have non-tectonic applications such as hydrologic studies, reference frame determination, and atmospheric studies. Station quality parameters

  13. Nature and distribution of geological domains at the Africa-Eurasia plate boundary off SW Iberia and regional geodynamic implications

    Science.gov (United States)

    Martínez-Loriente, Sara; Sallarès, Valentí; Gràcia, Eulàlia; Bartolome, Rafael

    2014-05-01

    We present a new classification of geological domains at the Africa-Eurasia plate boundary off SW Iberia, together with a regional geodynamic reconstruction spanning from the Mesozoic extension to the Neogene-to-present-day convergence. It is based on seismic velocity and density models along two regional wide-angle seismic transects, one running NW-SE from the Horseshoe to the Seine abyssal plains, and the other running N-S from S Portugal to the Seine Abyssal Plain, combined with previously available information. The seismic velocity and density structure at the Seine Abyssal Plain and the internal Gulf of Cadiz indicates the presence of a highly heterogeneous oceanic crust, similar to that described in ultra-slow spreading centers, whereas in the Horseshoe and Tagus abyssal plains, the basement structure resembles that of exhumed mantle sections identified in the Northern Atlantic margin. The integration of all this new information allows defining the presence of three oceanic domains offshore SW Iberia: (1) the Seine Abyssal Plain domain, generated during the first stages of slow seafloor spreading in the NE Central Atlantic (Early Jurassic); (2) the Gulf of Cadiz domain, made of oceanic crust generated in the Alpine-Tethys spreading system between Iberia and Africa, which was coeval with the formation of the Seine Abyssal Plain domain and lasted up to the North Atlantic continental break-up (Late Jurassic); and (3) the Gorringe Bank domain, mainly made of rocks exhumed from the mantle with little synchronous magmatism, which formed during the first stages of North Atlantic opening. Our models suggest that the Seine Abyssal Plain and Gulf of Cadiz domains are separated by the Lineament South strike-slip fault, whereas the Gulf of Cadiz and Gorringe Bank domains appear to be limited by a deep thrust fault located at the center of the Horseshoe Abyssal Plain. The formation and evolution of these three domains during the Mesozoic is key to understand the sequence

  14. Constraints on fault slip rates of the southern California plate boundary from GPS velocity and stress inversions

    Science.gov (United States)

    Becker, T.W.; Hardebeck, J.L.; Anderson, G.

    2005-01-01

    We use Global Positioning System (GPS) velocities and stress orientations inferred from seismicity to invert for the distribution of slip on faults in the southern California plate-boundary region. Of particular interest is how long-term slip rates are partitioned between the Indio segment of the San Andreas fault (SAF), the San Jacinto fault (SJF) and the San Bernardino segment of the SAE We use two new sets of constraints to address this problem. The first is geodetic velocities from the Southern California Earthquake Center's (SCEC) Crustal Motion Map (version 3 by Shen et al.), which includes significantly more data than previous models. The second is a regional model of stress-field orientations at seismogenic depths, as determined from earthquake focal mechanisms. While GPS data have been used in similar studies before, this is the first application of stress-field observations to this problem. We construct a simplified model of the southern California fault system, and estimate the interseismic surface velocities using a backslip approach with purely elastic strain accumulation, following Meade et al. In addition, we model the stress orientations at seismogenic depths, assuming that crustal stress results from the loading of active faults. The geodetically derived stressing rates are found to be aligned with the stress orientations from seismicity. We therefore proceed to invert simultaneously GPS and stress observations for slip rates of the faults in our network. We find that the regional patterns of crustal deformation as imaged by both data sets can be explained by our model, and that joint inversions lead to better constrained slip rates. In our preferred model, the SJF accommodates ???15 mm yr-1 and the Indio segment of the SAF ???23 mm yr-1 of right-lateral motion, accompanied by a low slip rate on the San Bernardino segment of the SAF 'Anomalous' fault segments such as around the 1992 Mw = 7.3 Landers surface rupture can be detected. There, observed

  15. The Teisseyre-Tornquist Zone - early Palaeozoic strike-slip plate boundary or Ediacaran rifted margin of Baltica?

    Science.gov (United States)

    Mazur, Stanislaw; Krzywiec, Piotr; Malinowski, Michal; Lewandowski, Marek; Buffenmeyer, Vinton; Green, Christopher

    2016-04-01

    area is dominated by high density lower crustal bodies similar to those that are found along present-day passive continental margins. Moreover, an extensive succession of the uppermost Neoproterozoic sediments is emplaced outboard of the southeastern section of the TTZ. These results obtained do not support the occurrence of a Palaeozoic terrane boundary along the TTZ. Instead, it is suggested that the crystalline basement of the EEC extends westward beyond the TTZ and continues in the substratum of the Permo-Mesozoic basin of central and western Poland. If the crustal keel underneath the TTZ indeed represents a fossil plate boundary, it must have formed in the Precambrian during the amalgamation of the Rodinia supercontinent. However, the contrast of crustal thickness across the TTZ between the EEC and the adjacent Palaeozoic Platform may have formed later during the Ediacaran rifting and subsequent break-up of the Tornquist Ocean. The Caledonian collisional suture must be located farther southwest in western Poland or NE Germany and deeply concealed beneath a thick cover of Palaeozoic and younger sediments.

  16. EQUIVALENCE BETWEEN EXACT INTERNAL CONTROLLABILITY OF THE KIRCHHOFF PLATE-LIKE EQUATION AND THE WAVE EQUATION

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    When the rotatory inertia is taken into account, vibrations of a linear plate can be described by the Kirchhoff plate equation. Consider this equation with locally distributed control forces and some boundary condition which is the simply supported boundary condition for a rectangular plate. In this paper, the authors establish exact controllability of the system in terms of the equivalence to exact internal controllability of the wave equation, by means of a frequency domain characterization of exact controllability introduced recently in [11].

  17. The Study on the Block Boundary's Driving Forces and Tectonic Stress Field of China Mainland and Its Adjacent Areas Using GPS Data

    Institute of Scientific and Technical Information of China (English)

    Du Zhi-xing; Qu Ji-kun; Han Bao-min; Jin Feng-xiang; Chai Yan-ju

    2003-01-01

    After reviewing the inversion study on the driving forces of China mainland and its adjacent areas, the inversion computation is made by means of genetic finite element method and covering complex method based on the displacement observations of the Crustal Movement Observation Network of China. The whole procedures of inversion study, including parameter selection, computation conditions, inversion analysis and interpretation, are given out in details. Then some conclusions are drawn:(1)the main driving forces acting on China mainland are still from the collision of Indian plate with Eurasian plate;(2)the driving forces of Pacific plate and Philippine plate are significant to the eastern China;(3)the back basin of Japan sea arc is continuously extending;(4)the forces from north prevent the northern motion of China.

  18. 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.

  19. Effects of boundary layer on flame propagation generated by forced ignition behind an incident shock wave

    Science.gov (United States)

    Ishihara, S.; Tamura, S.; Ishii, K.; Kataoka, H.

    2016-09-01

    To study the effects of the boundary layer on the deflagration to detonation transition (DDT) process, the mixture behind an incident shock wave was ignited using laser breakdown. Ignition timing was controlled so that the interaction of the resulting flame with a laminar or turbulent boundary layer could be examined. In the case of the interaction with a laminar boundary layer, wrinkling of the flame was observed after the flame reached the corner of the channel. On the other hand, interaction with the turbulent boundary layer distorted the flame front and increased the spreading rate of the flame followed by prompt DDT. The inner structure of the turbulent boundary layer plays an important role in the DDT process. The region that distorted the flame within the turbulent boundary layer was found to be the intermediate region 0.01DDT was independent of the ignition position. The effect of the boundary layer on the propagating flame, thus, became relatively small after the accelerating flame was generated.

  20. 3-D simulation of temporal change in tectonic deformation pattern and evolution of the plate boundary around the Kanto Region of Japan due to the collision of the Izu-Bonin Arc

    Science.gov (United States)

    Hashima, A.; Sato, T.; Ito, T.; Miyauchi, T.; Furuya, H.; Tsumura, N.; Kameo, K.; Yamamoto, S.

    2010-12-01

    The Kanto region of Japan is in a highly complex tectonic setting with four plates interacting with each other: beneath Kanto, situated on the Eurasian and North American plates, the Philippine sea plate subducts and the Pacific plate further descends beneath the North American and Philippine sea plates, forming the unique trench-trench-trench triple junction on the earth. In addition, the Izu-Bonin (Ogasawara) arc on the Philippine sea plate is colliding with the Japan islands, which is considered to be a significant effect on the tectonics of Kanto. To reveal the present crustal structure and the present internal stress fields in such a complex tectonic setting, it is essential to comprehend them through the long-term tectonic evolution process. In this study, we estimate the temporal change in tectonic deformation pattern along with the geometry of the plate boundary around Kanto by numerical simulation with a kinematic plate subduction model based on the elastic dislocation theory. This model is based on the idea that mechanical interaction between plates can rationally be represented by the increase of the displacement discontinuity (dislocation) across plate interfaces. Given the 3-D geometry of plate interfaces, the distribution of slip rate vectors for simple plate subduction can be obtained directly from relative plate velocities. In collision zones, the plate with arc crust cannot easily descend because of its buoyancy. This can be represented by giving slip-rate deficit. When crustal deformation occurs, it also causes change in geometry of the plate boundary itself. This geometry change sensitively affects mechanical interaction at the plate boundary. Then the renewed plate-to-plete interaction alters crustal deformation rates. This feedback system has a large effect on collision zones. Indeed, the plate boundary around the Izu peninsula, the northernmost end of the Izu-Bonin arc, intends landward as large as 100 km. Iterating this effect sequentially

  1. Finite difference analysis of hydromagnetic mixed convective mass diffusion boundary layer flow past an accelerated vertical porous plate through a porous medium with suction

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.S. [Department of Physics, K.B.D.A.V. College, Nirakarpur, Khordha-752 019 (Odisha) (India); Saran, M.R. [Department of Physics, Maharishi College of Natural Law, Sahid Nagar, Bhubaneswar-751 007 (Odisha) (India); Mohanty, S. [Department of Chemistry, Christ College, Mission Road, Cuttack-753 001 (Odisha) (India); Padhy, R.K. [Department of Physics, ODM Public School, Shishu Vihar, Patia, Bhubaneswar-751 024 (Odisha) (India)

    2013-07-01

    This paper focuses on the unsteady hydromagnetic mixed convective heat and mass transfer boundary layer flow of a viscous incompressible electrically conducting fluid past an accelerated infinite vertical porous flat plate in a porous medium with suction in presence of foreign species such as H2, He, H2O vapour and NH3. The governing equations are solved both analytically and numerically using error function and finite difference scheme. The flow phenomenon has been characterized with the help of flow parameters such as magnetic parameter (M), suction parameter (a), permeability parameter (Kp), Grashof number for heat and mass transfer (Gr, Gc), Schmidt number (Sc) and Prandtl number (Pr). The effects of the above parameters on the fluid velocity, temperature, concentration distribution, skin friction and heat flux have been analyzed and the results are presented graphically and discussed quantitatively for Grashof number Gr>0 corresponding to cooling of the plate. It is observed that a growing magnetic parameter (M) retards the velocity of the flow field at all points and a greater suction leads to a faster reduction in the velocity of the flow field. Further, as we increase the permeability parameter (Kp) and the Grashof numbers for heat and mass transfer (Gr, Gc) the velocity of the flow field enhances at all points, while a greater suction/Prandtl number leads to a faster cooling of the plate. It is also observed that a more diffusive species has a significant decrease in the concentration boundary layer of the flow field and a growing suction parameter enhances both skin friction (T') and heat flux (Nu) at the wall corresponding to cooling of the plate (Gr>0).

  2. Abbot Ice Shelf, structure of the Amundsen Sea continental margin and the southern boundary of the Bellingshausen Plate seaward of West Antarctica.

    Science.gov (United States)

    Cochran, James R; Tinto, Kirsty J; Bell, Robin E

    2015-05-01

    Inversion of NASA Operation IceBridge airborne gravity over the Abbot Ice Shelf in West Antarctica for subice bathymetry defines an extensional terrain made up of east-west trending rift basins formed during the early stages of Antarctica/Zealandia rifting. Extension is minor, as rifting jumped north of Thurston Island early in the rifting process. The Amundsen Sea Embayment continental shelf west of the rifted terrain is underlain by a deeper, more extensive sedimentary basin also formed during rifting between Antarctica and Zealandia. A well-defined boundary zone separates the mildly extended Abbot extensional terrain from the deeper Amundsen Embayment shelf basin. The shelf basin has an extension factor, β, of 1.5-1.7 with 80-100 km of extension occurring across an area now 250 km wide. Following this extension, rifting centered north of the present shelf edge and proceeded to continental rupture. Since then, the Amundsen Embayment continental shelf appears to have been tectonically quiescent and shaped by subsidence, sedimentation, and the advance and retreat of the West Antarctic Ice Sheet. The Bellingshausen Plate was located seaward of the Amundsen Sea margin prior to incorporation into the Antarctic Plate at about 62 Ma. During the latter part of its independent existence, Bellingshausen plate motion had a clockwise rotational component relative to Antarctica producing convergence across the north-south trending Bellingshausen Gravity Anomaly structure at 94°W and compressive deformation on the continental slope between 94°W and 102°W. Farther west, the relative motion was extensional along an east-west trending zone occupied by the Marie Byrd Seamounts. Abbot Ice Shelf is underlain by E-W rift basins created at ∼90 Ma Amundsen shelf shaped by subsidence, sedimentation, and passage of the ice sheet Bellingshausen plate boundary is located near the base of continental slope and rise.

  3. Large-scale right-slip displacement on the East San Francisco Bay Region fault system, California: Implications for location of late Miocene to Pliocene Pacific plate boundary

    Science.gov (United States)

    McLaughlin, R.J.; Sliter, W.V.; Sorg, D.H.; Russell, P.C.; Sarna-Wojcicki, A. M.

    1996-01-01

    . Major transpression across the boundary between the Pacific and North American plates at about 3 to 5 Ma would have resulted in the transfer of significant slip back to the San Francisco Peninsula segment of the San Andreas fault. Since that time, the ESFBR fault system has continued to slip at rates of 11-14 mm/yr. If this interpretation is valid, the ESFBR fault system was the Pacific-North American plate boundary between 8 and 6 Ma, and this boundary has migrated both eastward and westward with time, in response to changing plate margin geometry and plate motions.

  4. From free jets to clinging wall jets: The influence of a horizontal boundary on a horizontally forced buoyant jet

    Science.gov (United States)

    Burridge, H. C.; Hunt, G. R.

    2017-02-01

    We investigate the incompressible turbulent jet formed when buoyant fluid is steadily ejected horizontally from a circular source into an otherwise quiescent uniform environment. As our primary focus, we introduce a horizontal boundary beneath the source. For sufficiently small separations, the jet attaches and clings to the boundary, herein the "clinging jet," before, farther downstream, the jet is pulled away from the boundary by the buoyancy force. For larger source-boundary separations, the buoyant jet is free to rise under the action of the buoyancy force, herein the "free jet." Based on measurements of saline jets in freshwater surroundings we deduce the conditions required for a jet to cling. We present a data set that spans a broad range of source conditions for the variation in volume flux (indicative of entrainment), jet perimeter, and jet centerline for both "clinging" and "free" jets. For source Froude numbers Fr0≥12 the data collapse when scaled, displaying universal behaviors for both clinging and free jets. Our results for the variation in the volume flux across horizontal planes, π Qjet , show that within a few jet lengths of the source, π Qjet for the clinging jet exceeds that of a free jet with identical source conditions. However, when examined in a coordinate following the jet centerline π Qjet for free jets is greater. Finally, we propose a new parametrization for an existing integral model which agrees well with our experimental data as well as with data from other studies. Our findings offer the potential to tailor the dilution of horizontal buoyant jets by altering the distance at which they are released from a boundary.

  5. TEMPERATURE PROFILES OF LOCAL THERMAL NONEQUILIBRIUM FOR THERMAL DEVELOPING FORCED CONVECTION IN POROUS MEDIUM PARALLEL PLATE CHANNEL

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao; LIU Xue-mei

    2006-01-01

    Based on the two-energy equation model, taking into account viscous dissipation due to the interaction between solid skeleton and pore fluid flow, temperature expressions of the solid skeleton and pore fluid flow are obtained analytically for the thermally developing forced convection in a saturated porous medium parallel plate channel,with walls being at constant temperature. It is proved that the temperatures of the two phases for the local thermal nonequilibrium approach to the temperature derived from the one-energy equation model for the local thermal equilibrium when the heat exchange coefficient goes to infinite. The temperature profiles are shown in figures for different dimensionless parameters and the effects of the parameters on the local thermal nonequilibrium are revealed by parameter study.

  6. Influence of Damping on the Dynamical Behavior of the Electrostatic Parallel-plate and Torsional Actuators with Intermolecular Forces

    Science.gov (United States)

    Lin, Wen-Hui; Zhao, Ya-Pu

    2007-01-01

    The influence of damping on the dynamical behavior of the electrostatic parallel-plate and torsional actuators with the van der Waals (vdW) or Casimir force (torque) is presented. The values of the pull-in parameters and the number of the equilibrium points do not change whether there is damping or not. The ability of equilibrium points is varied with the appearance of damping. One equilibrium point is an unstable saddle with a different damping coefficient, the other equilibrium point is a stable node when the damping coefficient is greater than some critical value, and otherwise it is a stable focus. Then there are two heteroclinic orbits passing from the unstable saddle point to the stable node or focus.

  7. Influence of Damping on the Dynamical Behavior of the Electrostatic Parallel-plate and Torsional Actuators with Intermolecular Forces

    Directory of Open Access Journals (Sweden)

    Ya-Pu Zhao

    2007-11-01

    Full Text Available The influence of damping on the dynamical behavior of the electrostaticparallel-plate and torsional actuators with the van der Waals (vdW or Casimir force(torque is presented. The values of the pull-in parameters and the number of theequilibrium points do not change whether there is damping or not. The ability ofequilibrium points is varied with the appearance of damping. One equilibrium point is anunstable saddle with a different damping coefficient, the other equilibrium point is astable node when the damping coefficient is greater than some critical value, andotherwise it is a stable focus. Then there are two heteroclinic orbits passing from theunstable saddle point to the stable node or focus.

  8. Long-and Short-Term Self-Learning Models of Rolling Force in Rolling Process Without Gaugemeter of Plate

    Institute of Scientific and Technical Information of China (English)

    ZHU Fu-wen; ZENG Qing-liang; HU Xian-lei; LI Xi-an; LIU Xiang-hua

    2009-01-01

    .Owing to a lack of gaugemeter and the variety of steel grades and standards in some plate mills,the longand short-term self-learning models of rolling force based on gauge soft-measuring with high precision were brought up.The soft-measuring method and target value locked method were used in these models to confirm the actual exit gauge of passes,and thick layer division and exponential smoothing method were used to dispose the deformation resistance parameter,which could be calculated from the actual data of the rolling process.The correlative mathematical methods can also be adapted to self-learning with gaugemeter.The models were applied to the process control system of AGC (automatic gauge control) reconstruction on 2 800 mm finishing mill of Anyang steel and favorable effect was obtained.

  9. Consistency of Field-Based Measures of Neuromuscular Control Using Force-Plate Diagnostics in Elite Male Youth Soccer Players.

    Science.gov (United States)

    Read, Paul J; Oliver, Jon L; Croix, Mark Ba De Ste; Myer, Gregory D; Lloyd, Rhodri S

    2016-12-01

    Read, P, Oliver, JL, Croix, MD, Myer, GD, and Lloyd, RS. Consistency of field-based measures of neuromuscular control using force-plate diagnostics in elite male youth soccer players. J Strength Cond Res 30(12): 3304-3311, 2016-Deficits in neuromuscular control during movement patterns such as landing are suggested pathomechanics that underlie sport-related injury. A common mode of assessment is measurement of landing forces during jumping tasks; however, these measures have been used less frequently in male youth soccer players, and reliability data are sparse. The aim of this study was to examine the reliability of a field-based neuromuscular control screening battery using force-plate diagnostics in this cohort. Twenty-six pre-peak height velocity (PHV) and 25 post-PHV elite male youth soccer players completed a drop vertical jump (DVJ), single-leg 75% horizontal hop and stick (75%HOP), and single-leg countermovement jump (SLCMJ). Measures of peak landing vertical ground reaction force (pVGRF), time to stabilization, time to pVGRF, and pVGRF asymmetry were recorded. A test-retest design was used, and reliability statistics included change in mean, intraclass correlation coefficient, and coefficient of variation (CV). No significant differences in mean score were reported for any of the assessed variables between test sessions. In both groups, pVGRF and asymmetry during the 75%HOP and SLCMJ demonstrated largely acceptable reliability (CV ≤ 10%). Greater variability was evident in DVJ pVGRF and all other assessed variables, across the 3 protocols (CV range = 13.8-49.7%). Intraclass correlation coefficient values ranged from small to large and were generally higher in the post-PHV players. The results of this study suggest that pVGRF and asymmetry can be reliably assessed using a 75%HOP and SLCMJ in this cohort. These measures could be used to support a screening battery for elite male youth soccer players and for test-retest comparison.

  10. Effect of strain-weakening on Oligocene-Miocene self-organization of the Australian-Pacific plate boundary fault in southern New Zealand: Insights from numerical modelling

    Science.gov (United States)

    Feng, Xiaojun; Jessell, Mark Walter; Amponsah, Prince Ofori; Martin, Roland; Ganne, Jérôme; Liu, Daqing; Batt, Geoffrey E.

    2016-10-01

    Tectonic inheritance acquired from past geological events can control the formation of new plate boundaries. The aim of this paper is to explore the role of inherited NE and NW trending fabrics and their rheological influence on the propagation of Oligocene-Miocene strike-slip faulting that matured to become the Australian-Pacific plate boundary fault in southern New Zealand. Strain weakening plays a significant role in controlling the formation, growth and evolution of strain localization. In this study, three-dimensional thermo-mechanical models have been used to explore the effect of strain weakening on the Oligocene-Miocene self-organization of strain localization. Strain weakening is simulated through decreasing either the coefficient of friction of upper crust, its cohesion, or the rheological viscosity contrast between the inherited structures and their surrounding wall rocks. Viscosity contrast is obtained by varying the viscosity of inherited structures. Softening coefficient (α) is a measure of strain weakening. Our experiments robustly demonstrate that a primary boundary shear zone becomes mature quicker when softening coefficients are increased. Deformation is focused along narrow high-strain shear zones in the centre of the model when the softening coefficients are high, whereas the strain is more diffuse with many shear zones spread over the model and possibly some high-strain shear zones focused near one border at lower softening coefficients. Varying the viscosity contrast has less effect on the distribution of maximum finite strain. Under simple-shear boundary conditions, NW trending inherited structures make a major contribution to forming early zones of highly focused strain, up to a shear strain of about γ = 3.7. During this process, most NE-trending structures move and rotate passively, accommodate less strain, or even be abandoned through time.

  11. A numerical method for solving the boundary layer equations of laminar natural convention about a vertical plate

    Institute of Scientific and Technical Information of China (English)

    Liancun Zheng; Chen Liang; Xinxin Zhang

    2007-01-01

    An improved shooting method was presented for solving the natural convention boundary layer equations,with a coupling of the velocity field to the temperature field.The numerical results are consistent with the approximate solution obtained by former researchers.

  12. Numerical Study of Non-Newtonian Boundary Layer Flow of Jeffreys Fluid Past a Vertical Porous Plate in a Non-Darcy Porous Medium

    Science.gov (United States)

    Ramachandra Prasad, V.; Gaffar, S. Abdul; Keshava Reddy, E.; Bég, O. Anwar

    2014-07-01

    Polymeric enrobing flows are important in industrial manufacturing technology and process systems. Such flows are non-Newtonian. Motivated by such applications, in this article we investigate the nonlinear steady state boundary layer flow, heat, and mass transfer of an incompressible Jefferys non-Newtonian fluid past a vertical porous plate in a non-Darcy porous medium. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a versatile, implicit, Keller-box finite-difference technique. The numerical code is validated with previous studies. The influence of a number of emerging non-dimensional parameters, namely Deborah number (De), Darcy number (Da), Prandtl number (Pr), ratio of relaxation to retardation times (λ), Schmidt number (Sc), Forchheimer parameter (Λ), and dimensionless tangential coordinate (ξ) on velocity, temperature, and concentration evolution in the boundary layer regime are examined in detail. Furthermore, the effects of these parameters on surface heat transfer rate, mass transfer rate, and local skin friction are also investigated. It is found that the boundary layer flow is decelerated with increasing De and Forchheimer parameter, whereas temperature and concentration are elevated. Increasing λ and Da enhances the velocity but reduces the temperature and concentration. The heat transfer rate and mass transfer rates are found to be depressed with increasing De and enhanced with increasing λ. Local skin friction is found to be decreased with a rise in De, whereas it is elevated with increasing λ. An increasing Sc decreases the velocity and concentration but increases temperature.

  13. Loadcell supports for a dynamic force plate. [using piezoelectric tranducers and electromyography to study human gait

    Science.gov (United States)

    Keller, C. W.; Musil, L. M.; Hagy, J. L.

    1975-01-01

    An apparatus was developed to accurately measure components of force along three mutually perpendicular axes, torque, and the center of pressure imposed by the foot of a subject walking over its surface. The data obtained were used to supplement high-speed motion picture and electromyographic (EMG) data for in-depth studies of normal or abnormal human gait. Significant features of the design (in particular, the mechanisms used to support the loadcell transducers) are described. Results of the development program and typical data obtained with the device are presented and discussed.

  14. Forced Convective Heat Transfer in a Plate Channel Filled with Solid Particles

    Institute of Scientific and Technical Information of China (English)

    Pei-XueJiang; Ze-PeiRen; 等

    1996-01-01

    A numerical study of fluid flow and convective heat transfer in a plate channel filled with solid(metallic)perticles is presented in this paper,The study uses the thermal equilibrium model and a newly developed numerical model which does not assume idealized local thermal equilibrium between the solid particles and the fluid.The numerical simulation results are compared with the experimental data in reference[2].The paper investigates the effects of the assumption of local thermal equilibrium versus non-thermal equilibrium,the thermal conductivity of the solid particles and the particle diameter on convective heat transfer.For the conditions studied.the convective heat transfer and the temperature filed assuming local thermal equilibrium are much different from that for the non-thermal equilibrium assumption when the difference between the solid and fluid thermal conductivities is large,The relative values of the thermal conductivities of the solid particles and the fluid also have a profound effect on the temperature distribution in the channel.The pressure drop decreases as the particle diameter increases and the convective heat transfer coefficient may decrease of increase as the particle diameter increasws depending on the values of ε,λs,λf,λd,αu,ρu.

  15. 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.; Klaeschen, D.; Monaco, C.; Neri, G.; Nijholt, N.; Orecchio, B.; Wortel, R.

    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 NNW

  16. 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.; 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 NNW

  17. A forced fractional Schrödinger equation with a Neumann boundary condition

    Science.gov (United States)

    Esquivel, L.; Kaikina, Elena I.

    2016-07-01

    We study the initial-boundary value problem for the nonlinear fractional Schrödinger equation {ut+i(uxx+12π∫0∞sign(x-y)|x-y|12uy( y)dy)+i|u|2u=0, t>0, x>0u(x,0)=u0(x), x>0,ux(0,t)=h(t), t>0. We prove the global-in-time existence of solutions for a nonlinear fractional Schrödinger equation with inhomogeneous Neumann boundary conditions. We are also interested in the study of the asymptotic behaviour of the solutions.

  18. On the correlation between force production and the flow field around a flapping flat-plate wing

    Science.gov (United States)

    Öz, Sören; Krishna, Swathi; Mulleners, Karen

    2015-11-01

    One of the several sophisticated flight skills that insects exhibit is hovering, which is accomplished largely by modulating the wing kinematics and thereby the flow field around the wings. Along with the prolonged attachment of the leading edge vortex, the wing reversal mechanisms form the basis by which insects regulate the magnitude and direction of forces produced. The duration and starting point of these directional flips are studied in the current experimental investigation. Particle image velocimetry is conducted to evaluate the flow features inherent to changes in wing reversal during the stroke of a flat plate, which is modelled based on hoverfly characteristics. The duration of rotation is one-third of the total time period. A +10% phase shift is used for delayed rotation, a -10% phase shift for advanced rotation. Phase-averaged data is analysed to understand the influence of a delayed or advanced rotation on the formation and evolution of large and small scale structures, their interactions with the wing, and disintegration. Additionally, force data is used to quantify the effects of phase-shift in terms of lift and drag variation and is correlated with the vortex dynamics.

  19. Quadratic Convective Flow of a Micropolar Fluid along an Inclined Plate in a Non-Darcy Porous Medium with Convective Boundary Condition

    Science.gov (United States)

    RamReddy, Ch.; Naveen, P.; Srinivasacharya, D.

    2017-06-01

    The objective of the present study is to investigate the effect of nonlinear variation of density with temperature and concentration on the mixed convective flow of a micropolar fluid over an inclined flat plate in a non-Darcy porous medium in the presence of the convective boundary condition. In order to analyze all the essential features, the governing non-dimensional partial differential equations are transformed into a system of ordinary differential equations using a local non-similarity procedure and then the resulting boundary value problem is solved using a successive linearisation method (SLM). By insisting the comparison between vertical, horizontal and inclined plates, the physical quantities of the flow and its characteristics are exhibited graphically and quantitatively with various parameters. An increase in the micropolar parameter and non-Darcy parameter tend to increase the skin friction and the reverse change is observed in wall couple stress, mass and heat transfer rates. The influence of the nonlinear concentration parameter is more prominent on all the physical characteristics of the present model, compared with that of nonlinear temperature parameter.

  20. Numerical solution of thermo-solutal mixed convective slip flow from a radiative plate with convective boundary condition

    Institute of Scientific and Technical Information of China (English)

    M J UDDIN; O Anwar BG; M N UDDIN; A I Md ISMAIL

    2016-01-01

    A mathematical model for mixed convective slip flow with heat and mass transfer in the presence of thermal radiation is presented. A convective boundary condition is included and slip is simulated via the hydrodynamic slip parameter. Heat generation and absorption effects are also incorporated. The Rosseland diffusion flux model is employed. The governing partial differential conservation equations are reduced to a system of coupled, ordinary differential equations via Lie group theory method. The resulting coupled equations are solved using shooting method. The influences of the emerging parameters on dimensionless velocity, tempera- ture and concentration distributions are investigated. Increasing radiative-conductive parameter accelerates the boundary layer flow and increases temperature whereas it depresses concentration. An elevation in convection-conduction parameter also accelerates the flow and temperatures whereas it reduces concentrations. Velocity near the wall is considerably boosted with increasing momentum slip parameter although both temperature and concentration boundary layer thicknesses are decreased. The presence of a heat source is found to increase momentum and thermal boundary layer thicknesses but reduces concentration boundary layer thickness. Excelle- nt correlation of the numerical solutions with previous non-slip studies is demonstrated. The current study has applications in bio- reactor diffusion flows and high-temperature chemical materials processing systems.

  1. Large vertical motions and basin evolution in the Outer Continental Borderland off Southern California associated with plate boundary development and continental rifting

    Science.gov (United States)

    Nicholson, C.; Sorlien, C. C.; Schindler, C. S.; De Hoogh, G.

    2011-12-01

    The Continental Borderland offshore southern California occupies a strategic position along the continental margin. It was the locus of ~75% of Pacific-North America displacement history, it helped accommodate the large-scale (>90°) tectonic rotation of the Western Transverse Ranges province, and is still accommodating potentially 20% of PAC-NAM plate motion today. As such, it represents an ideal natural laboratory to investigate plate boundary evolution and basin development associated with transform initiation, oblique continental rifting, transrotation and transpression. We have been using newly released grids of high-quality industry multichannel seismic (MCS) reflection data, combined with multibeam bathymetry and offshore well data to map and construct digital 3D fault surfaces and stratigraphic reference horizons over large parts of the Outer Continental Borderland. These 3D surfaces of structure and stratigraphy can be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of plate boundary deformation. In the northern Outer Borderland, mapping in Santa Cruz basin, and across both Santa Rosa and Santa Cruz-Catalina ridges reveals a pattern of interacting high-and low-angle faults, fault reactivation, basin subsidence, folding, and basin inversion. Subsidence since early-Miocene time is significant (up to 4 km) and is much larger than predicted by simple thermal cooling models of continental rifting. This requires additional tectonic components to drive this regional subsidence and subsequent basin inversion. Farther south, a more en echelon pattern of ridges and basins suggests a distributed component of right-lateral shear also contributed to much of the modern Borderland seafloor topography, including major Borderland basins. Vertical motions of uplift and subsidence can be estimated from a prominent early-Miocene unconformity that likely represents a regional, paleo-horizontal, near

  2. 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

  3. A NUMERICAL STUDY OF FORCED CONVECTION HEAT TRANSFER OVER A SERIES OF FLAT TUBES BETWEEN PARALLEL PLATES

    Directory of Open Access Journals (Sweden)

    M.M. Rahman

    2012-12-01

    Full Text Available This paper presents the numerical study on two-dimensional forced convection heat transfer across three in-line flat tubes confined in a channel under incompressible, steady-state conditions. This system is solved in body-fitted coordinates (BFC using the finite volume method (FVM. The constant heat flux is imposed on the surface of the tubes as the thermal boundary conditions. The range of the longitudinal pitch-to-diameter ratio (SL/Ds of 2.0–4.0 is considered, the Reynolds number varies within the range 25–300, and the Prandtl number is taken as 0.7. The temperature contours, local Nusselt number distributions at the tube surface and mean Nusselt number were analyzed. The strength of the heat transfer between the surface of the tubes and the air flow increases with an increase in Reynolds number and pitch-to-diameter ratio.

  4. Alteration and dehydration of subducting oceanic crust within subduction zones: implications for décollement step-down and plate-boundary seismogenesis

    Science.gov (United States)

    Kameda, Jun; Inoue, Sayako; Tanikawa, Wataru; Yamaguchi, Asuka; Hamada, Yohei; Hashimoto, Yoshitaka; Kimura, Gaku

    2017-04-01

    The alteration and dehydration of predominantly basaltic subducting oceanic crustal material are thought to be important controls on the mechanical and hydrological properties of the seismogenic plate interface below accretionary prisms. This study focuses on pillow basalts exposed in an ancient accretionary complex within the Shimanto Belt of southwest Japan and provides new quantitative data that provide insight into clay mineral reactions and the associated dehydration of underthrust basalts. Whole-rock and clay-fraction X-ray diffraction analyses indicate that the progressive conversion of saponite to chlorite proceeds under an almost constant bulk-rock mineral assemblage. These clay mineral reactions may persist to deep crustal levels ( 320 °C), possibly contributing to the bulk dehydration of the basalt and supplying fluid to plate-boundary fault systems. This dehydration can also cause fluid pressurization at certain horizons within hydrous basalt sequences, eventually leading to fracturing and subsequent underplating of upper basement rock into the overriding accretionary prism. This dehydration-induced breakage of the basalt can explain variations in the thickness of accreted basalt fragments within accretionary prisms as well as the reported geochemical compositions of mineralized veins associated with exposed basalts in onland locations. This fracturing of intact basalt can also nucleate seismic rupturing that would subsequently propagate along seismogenic plate interfaces.[Figure not available: see fulltext.

  5. Boundary Element Method Solution in the Time Domain For a Moving Time-Dependent Force

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Kirkegaard, Poul Henning; Rasmussen, K. M.

    2001-01-01

    satisfy the radiation conditions exactly. In this paper a model based on the BEM is formulated for the solution of the mentioned problem. A numerical solution is obtained for the 2D plane strain case, and comparison is made with the results obtained from a corresponding FEM solution with an impedance...... absorbing boundary condition....

  6. Two-Dimensional Analytical Solution of the Laminar Forced Convection in a Circular Duct with Periodic Boundary Condition

    Directory of Open Access Journals (Sweden)

    M. R. Astaraki

    2012-01-01

    Full Text Available In the present study analytical solution for forced convection heat transfer in a circular duct with a special boundary condition has been presented, because the external wall temperature is a periodic function of axial direction. Local energy balance equation is written with reference to the fully developed regime. Also governing equations are two-dimensionally solved, and the effect of duct wall thickness has been considered. The temperature distribution of fluid and solid phases is assumed as a periodic function of axial direction and finally temperature distribution in the flow field, solid wall, and local Nusselt number, is obtained analytically.

  7. Recent regressions in plate boundary modelling - subducting the Himalayan orogen, and taking it with a growing grain of salt

    Science.gov (United States)

    Ueda, Kosuke

    2017-04-01

    One particular and maybe peculiar approach is to make inferences from the larger to the smaller scale. A promising starting point is the well-studied geodynamic plate subduction margin setup, from which many smaller-scale or process-specific findings have been successfully extracted. I present a series of models that were aiming to combine many of these findings to test the feasibility of conceptual models for the evolution of the Himalayan-Tibetan system. Are the Himalayas not feasible? Do the limitations lie within the method (i.e. 2D), the author, or the proposed history? Having not found the fundamental process control on major observables, I also move on to other regional settings. The presentation concludes with a display of early trial-stage of grain size evolution experiments, to plate-scale geodynamic processes.

  8. A revised estimate of Pacific-North America motion and implications for Western North America plate boundary zone tectonics

    Science.gov (United States)

    Demets, Charles; Gordon, Richard G.; Stein, Seth; Argus, Donald F.

    1987-01-01

    Marine magnetic profiles from the Gulf of Californa are studied in order to revise the estimate of Pacific-North America motion. It is found that since 3 Ma spreading has averaged 48 mm/yr, consistent with a new global plate motion model derived without any data. The present data suggest that strike-slip motion on faults west of the San Andreas is less than previously thought, reducing the San Andreas discrepancy with geodetic, seismological, and other geologic observations.

  9. Numerical Investigation on Submerged Horizontal Plate

    Institute of Scientific and Technical Information of China (English)

    康海贵; 王科

    2001-01-01

    Hydrodynamic characters on a horizontal, thin, rigid plate located beneath the free surface are numerically investigated. Assuming a linear, time-harmonic potential flow and utilizing Green identity, the governing Laplace equation can be simplified into Fredholm integral equation ofthe second kind. Supposing linear-order discontinuous elements along intersecting vertical boundaries, and by use of the boundary element method, numerical solution about source strength distribution on the plate can be changed into a series of algebraic equations. The 3D Green function is introduced to set up the integral equations, and the GMRES solver is performed for solving the large dense linear system of equations. The added-mass, damping force and exciting force are evaluated directly from the equations. It is found that the added-mass coefficient becomes negative for a range of frequencies when the plate is sufficiently close to the free surface.

  10. 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.

  11. Mathematical Study of Laminar Boundary Layer Flow and Heat Transfer of Tangenthyperbolic Fluid Pasta Vertical Porous Plate with Biot Number Effects

    Directory of Open Access Journals (Sweden)

    Ramachandra Prasad

    2016-01-01

    Full Text Available In this article, we investigate the nonlinear steady boundary layer flow and heat transfer of an incompressible Tangent Hyperbolicnon-Newtonian fluid from a vertical porous plate. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a second-order accurate implicit finite-difference Keller Box technique. The numerical code is validated with previous studies. The influence of a number of emerging non-dimensional parameters, namely the Weissenberg number (We, the power law index (n, Prandtl number (Pr, Biot number (, and dimensionless local suction parameter(on velocity and temperature evolution in the boundary layer regime are examined in detail. Furthermore the effects of these parameters on surface heat transfer rate and local skin friction are also investigated. Validation with earlier Newtonian studies is presented and excellent correlation achieved. It is found that velocity, Skin friction and Nusselt number (heat transfer rate are reduced with increasing Weissenberg number (We, whereas, temperature is enhanced. Increasing power law index (n enhances velocity and Nusselt number (heat transfer rate but temperature and Skin friction decrease. An increase in the Biot number ( is observed to enhance velocity, temperature, local skin friction and Nusselt number. An increasing Prandtl number, Pr, is found to decrease both velocity, temperature and skin friction but elevates heat transfer rate (Nusselt number. The study is relevant to chemical materials processing applications.

  12. Granular rheology: measuring boundary forces with laser-cut leaf springs

    Science.gov (United States)

    Tang, Zhu; Brzinski, Theodore A.; Daniels, Karen E.

    2017-06-01

    In granular physics experiments, it is a persistent challenge to obtain the boundary stress measurements necessary to provide full a rheological characterization of the dynamics. Here, we describe a new technique by which the outer boundary of a 2D Couette cell both confines the granular material and provides spatially- and temporally- resolved stress measurements. This key advance is enabled by desktop laser-cutting technology, which allows us to design and cut linearly-deformable walls with a specified spring constant. By tracking the position of each segment of the wall, we measure both the normal and tangential stress throughout the experiment. This permits us to calculate the amount of shear stress provided by basal friction, and thereby determine accurate values of μ(I).

  13. Tsujal Marine Survey: Crustal Characterization of the Rivera Plate-Jalisco Block Boundary and its Implications for Seismic and Tsunami Hazard Assessment

    Science.gov (United States)

    Bartolome, R.; Danobeitia, J.; Barba, D. C., Sr.; Nunez-Cornu, F. J.; Cameselle, A. L.; Estrada, F.; Prada, M.; Bandy, W. L.

    2014-12-01

    During the spring of 2014, a team of Spanish and Mexican scientists explored the western margin of Mexico in the frame of the TSUJAL project. The two main objectives were to characterize the nature and structure of the lithosphere and to identify potential sources triggering earthquakes and tsunamis at the contact between Rivera plate-Jalisco block with the North American Plate. With these purposes a set of marine geophysical data were acquired aboard the RRS James Cook. This work is focus in the southern part of the TSUJAL survey, where we obtain seismic images from the oceanic domain up to the continental shelf. Thus, more than 800 km of MCS data, divided in 7 profiles, have been acquired with a 6km long streamer and using an air-gun sources ranging from 5800 c.i. to 3540 c.i. Furthermore, a wide-angle seismic profile of 190 km length was recorded in 16 OBS deployed perpendicular to the coast of Manzanillo. Gravity and magnetic, multibeam bathymetry and sub-bottom profiler data were recorded simultaneously with seismic data in the offshore area. Preliminary stacked MCS seismic sections reveal the crustal structure in the different domains of the Mexican margin. The contact between the Rivera and NA Plates is observed as a strong reflection at 6 s two way travel time (TWTT), in a parallel offshore profile (TS01), south of Manzanillo. This contact is also identified in a perpendicular profile, TS02, along a section of more than 100 km in length crossing the Rivera transform zone, and the plate boundary between Cocos and Rivera Plates. Northwards, offshore Pto. Vallarta, the MCS data reveals high amplitude reflections at around 7-8.5 s TWTT, roughly 2.5-3.5 s TWTT below the seafloor, that conspicuously define the subduction plane (TS06b). These strong reflections which we interpret as the Moho discontinuity define the starting bending of subduction of Rivera Plate. Another clear pattern observed within the first second of the MCS data shows evidences of a bottom

  14. Sila kojom vazduh pritiska pokretnu ploču/Force of the air pressure on a moving plate

    Directory of Open Access Journals (Sweden)

    Leonid Ivanovich Gretchihin

    2014-10-01

    Full Text Available U radu je razrađena matematički model gasodinamičkog opstrujavanja ravne ploče pri njenom kretanju sa pozitivnim i negativnim napadnim uglom. Pokazano je da pri malim brzinama kretanja, silu uzgona i čeoni otpor određuje gasodinamički tok vazduha u izlaznoj oblasti opstrujavanja, a pri brzinama kretanja koje su bliske brzini zvuka odlučujuću ulogu vrši uzajamno udarno dejstvo ploče sa molekulima okružujuće sredine u ulaznoj oblasti opstrujavanja. Otcepljena struja iza ploče se ne pojavljuje pri malim brzinama kretanja. Određeni su uslovi kada čeoni otpor i sila uzgona ploče menjaju znak. / (ruski Razrabotana matematičeskaja model' gazodinamičeskogo obtekanija ploskoj plastiny pri ee dviženii s položitel'nym i otricatel'nym uglom ataki. Pokazano, čto pri malyh skorostjah dviženija plastiny pod''emnaja sila i lobovoe soprotivlenie opredeljajutsja gazodinamikoj tečenija vozduha v tyl'noj oblasti, a pri skorostjah dviženija blizkih k skorosti zvuka rešajuščuju rol' vypolnjaet udarnoe vzaimodejstvie plastiny s molekulami okružajuščej sredy v perednej oblasti. Sryvnoe tečenie za plastinoj pri malyh skorostjah dviženija ne voznikaet. Opredeleny uslovija, kogda lobovoe soprotivlenie i pod''emnaja sila plastiny izmenjaet znak. / This paper developed a mathematical model of gas dynamic fluid flow for a flat plate during its movement with positive and negative angles of attack. It is shown that at low velocities, the lifting force and the frontal resistance are determined by gasdynamic air flow in the fluid flow exit areawhile at velocities close to the speed of sound the decisive role is played by a mutualeffect of the pplate coliding with molecules of the surrounding environment in the fluid flow incidence field. The airflow behind the plate does not appear at low velocities. The conditions when the frontal resistance and the lifting force change the sign are determined.

  15. Single-phase liquid flow forced convection under a nearly uniform heat flux boundary condition in microchannels

    KAUST Repository

    Lee, Man

    2012-02-22

    A microchannel heat sink, integrated with pressure and temperature microsensors, is utilized to study single-phase liquid flow forced convection under a uniform heat flux boundary condition. Utilizing a waferbond-and-etch- back technology, the heat source, temperature and pressure sensors are encapsulated in a thin composite membrane capping the microchannels, thus allowing experimentally good control of the thermal boundary conditions. A three-dimensional physical model has been constructed to facilitate numerical simulations of the heat flux distribution. The results indicate that upstream the cold working fluid absorbs heat, while, within the current operating conditions, downstream the warmer working fluid releases heat. The Nusselt number is computed numerically and compared with experimental and analytical results. The wall Nusselt number in a microchannel can be estimated using classical analytical solutions only over a limited range of the Reynolds number, Re: both the top and bottom Nusselt numbers approach 4 for Re < 1, while the top and bottom Nusselt numbers approach 0 and 5.3, respectively, for Re > 100. The experimentally estimated Nusselt number for forced convection is highly sensitive to the location of the temperature measurements used in calculating the Nusselt number. © 2012 IOP Publishing Ltd.

  16. Impact of GCM boundary forcing on regional climate modeling of West African summer monsoon precipitation and circulation features

    Science.gov (United States)

    Kebe, Ibourahima; Sylla, Mouhamadou Bamba; Omotosho, Jerome Adebayo; Nikiema, Pinghouinde Michel; Gibba, Peter; Giorgi, Filippo

    2017-03-01

    In this study, the latest version of the International Centre for Theoretical Physics Regional Climate Model (RegCM4) driven by three CMIP5 Global Climate Models (GCMs) is used at 25 km grid spacing over West Africa to investigate the impact of lateral boundary forcings on the simulation of monsoon precipitation and its relationship with regional circulation features. We find that the RegCM4 experiments along with their multimodel ensemble generally reproduce the location of the main precipitation characteristics over the region and improve upon the corresponding driving GCMs. However, the provision of different forcing boundary conditions leads to substantially different precipitation magnitudes and spatial patterns. For instance, while RegCM4 nested within GFDL-ESM-2M and HadGEM2-ES exhibits some underestimations of precipitation and an excessively narrow Intertropical Convergence Zone, the MPI-ESM-MR driven run produces precipitation spatial distribution and magnitudes more similar to observations. Such a superior performance originates from a much better simulation of the interactions between baroclinicity, temperature gradient and African Easterly Jet along with an improved connection between the Isentropic Potential Vorticity, its gradient and the African Easterly Waves dynamics. We conclude that a good performing GCM in terms of monsoon dynamical features (in this case MPI-ESM-MR) is needed to drive RCMs in order to achieve a better representation of the West Africa summer monsoon precipitation.

  17. 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.

  18. 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.

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    Rita Choudhury

    2012-07-01

    Full Text Available 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 heat transfer and mass transfer have beenobtained. The velocity profile and the shearing stress have been illustrated graphically, for various values of flow parameters involved in the solution to observe the effect of visco-elastic parameter.

  1. Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Xavier Ortiz

    2015-03-01

    Full Text Available To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases.

  2. Magnitude of the prewetting boundary tension near wetting for short-range forces

    Science.gov (United States)

    Varea, C.; Robledo, A.

    1993-05-01

    We determine in a mean field approximation the spin-1/2 Ising model line tension τ along the boundary between surface states at the prewetting transition in the neighborhood of the wetting transition at bulk phase coexistence. We find very close agreement with the predictions of the interface displacement model for short-range interactions, i.e., τ increases (with a square-root dependence on the bulk external field h) towards a finite limit with diverging slope at wetting. Our findings help both in settling the discussion on the limiting value of τ and in understanding the origin of its singular behavior.

  3. Effect of Magnetic Field on Entropy Generation Due to Laminar Forced Convection Past a Horizontal Flat Plate

    Directory of Open Access Journals (Sweden)

    Moh'd A. Al-Nimr

    2004-06-01

    Full Text Available Magnetic field effect on local entropy generation due to steady two-dimensional laminar forced convection flow past a horizontal plate was numerically investigated. This study was focused on the entropy generation characteristics and its dependency on various dimensionless parameters. The effect of various dimensionless parameters, such as Hartmann number (Ha, Eckert number (Ec, Prandtl number (Pr, Joule heating parameter (R and the free stream temperature parameter (θ∞ on the entropy generation characteristics is analyzed. The dimensionless governing equations in Cartesian coordinate were solved by an implicit finite difference technique. The solutions were carried out for Ha2=0.5-3, Ec=0.01-0.05, Pr=1-5 and θ∞=1.1-2.5. It was found that, the entropy generation increased with increasing Ha, Ec and R. While, increasing the free stream temperature parameter, and Prandtl number tend to decrease the local entropy generation.

  4. Material dependence of Casimir interaction between a sphere and a plate: First analytic correction beyond proximity force approximation

    CERN Document Server

    Teo, L P

    2013-01-01

    We derive analytically the asymptotic behavior of the Casimir interaction between a sphere and a plate when the distance between them, $d$, is much smaller than the radius of the sphere, $R$. The leading order and next-to-leading order terms are derived from the exact formula for the Casimir interaction energy. They are found to depend nontrivially on the dielectric functions of the objects. As expected, the leading order term coincides with that derived using the proximity force approximation. The result on the next-to-leading order term complements that found by Bimonte, Emig and Kardar [Appl. Phys. Lett. \\textbf{100}, 074110 (2012)] using derivative expansion. Numerical results are presented when the dielectric functions are given by the plasma model or the Drude model, with the plasma frequency (for plasma and Drude models) and relaxation frequency (for Drude model) given respectively by 9eV and 0.035eV, the conventional values used for gold metal. It is found that if plasma model is used instead of Drude...

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

    Energy Technology Data Exchange (ETDEWEB)

    Hady, F. M.; Ibrahim, F. S. [Assiut University, Assiut (Egypt); Abdel-Gaied, S. M.; Eid, M. R. [Assiut University, The New Valley (Egypt)

    2011-08-15

    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 {Omega}, 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.

  6. Chemically Reacting MHD Boundary Layer Flow of Heat and Mass Transfer over a Moving Vertical Plate in a Porous Medium with Suction

    Directory of Open Access Journals (Sweden)

    K. GANGADHAR

    2013-01-01

    Full Text Available A mathematical model is presented for a two-dimensional, steady, incompressible electrically conducting, laminar free convection boundary layer flow of a continuously moving vertical porous plate in a chemically reactive and porous medium in the presence of a transverse magnetic field. The basic equations governing the flow are in the form of partial differential equations and have been reduced to a set of non-linear ordinary differential equations by applying suitable similarity transformations. The problem is tackled numerically using shooting techniques with the forth order Runga-Kutta method. Pertinent results with respect to embedded parameters are displayed graphically for the velocity,temperature and concentration profiles and were discussed quantitatively.

  7. Heat Transfer Analysis for Stationary Boundary Layer Slip Flow of a Power-Law Fluid in a Darcy Porous Medium with Plate Suction/Injection.

    Science.gov (United States)

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

    2015-01-01

    In this paper, we investigate the slip effects on the boundary layer flow and heat transfer characteristics of a power-law fluid past a porous flat plate embedded in the Darcy type porous medium. The nonlinear coupled system of partial differential equations governing the flow and heat transfer of a power-law fluid is transformed into a system of nonlinear coupled ordinary differential equations by applying a suitable similarity transformation. The resulting system of ordinary differential equations is solved numerically using Matlab bvp4c solver. Numerical results are presented in the form of graphs and the effects of the power-law index, velocity and thermal slip parameters, permeability parameter, suction/injection parameter on the velocity and temperature profiles are examined.

  8. Аsymptotic solution of a class thermoelasticity nonclassical boundary value problems for the package of an orthotropic plate of variable thickness

    Directory of Open Access Journals (Sweden)

    Aghalovyan M.L.

    2014-03-01

    Full Text Available We solve the non-classical boundary value problem for an orthotropic packet when on one of its front surface the corresponding components of the stress tensor are equal to zero and sets the value of the displacement vector. The task, in particular, is modeling the behavior of the lithospheric plates of the Earth, or a specific region of the earth's crust subject to tectonic movements of the fixed seismic stations, GPS and other measuring instruments. On the basis of three-dimensional equations of thermo-elasticity asymptotic method derived recurrence equations allow for a package of orthotropic layers of varying thickness. We derive recursive formulas for determining the components of the stress tensor and the displacement vector.

  9. 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.

  10. A verification of quantum field theory – measurement of Casimir force

    Indian Academy of Sciences (India)

    Anushree Roy; U Mohideen

    2001-02-01

    Here we review our work on measurement of the Casimir force between a large aluminum coated a sphere and flat plate using an atomic force microscope. The average statistical precision is 1% of the force measured at the closest separation. We have also shown nontrival boundary dependence of the Casimir force.

  11. Were they all giants? Perspectives on late Holocene plate-boundary earthquakes at the northern end of the Cascadia subduction zone

    Science.gov (United States)

    Hutchinson, Ian; Clague, John

    2017-08-01

    The relative magnitude of plate-boundary earthquakes at the northern end of the Cascadia subduction zone was assessed from the temporal concordance between the ages of coseismically buried late Holocene soils in southwest Washington, their counterparts in central and southern Cascadia, offshore turbidites, and paleoseismic deposits on the west coast of Vancouver Island. Only three of the seven buried soils in southwest Washington that can be reliably traced as buried soils or paleotsunami deposits in the coastal lowlands of south-central and southern Cascadia have well-dated counterparts in northern Cascadia. The three wide-ranging events date from Cascadia earthquakes Y (∼250 cal BP), U (∼1260 cal BP), and N (∼2520 cal BP). All three likely ruptured the entire plate margin, and therefore potentially qualify as ;giants; (Mw ≥ 9). Deposits that may derive from tsunamis generated by earthquakes S (∼1570 cal BP), L (∼2870 cal BP) and J (∼3360 cal BP) can also be found in northern Cascadia, but the ages of these deposits are not yet well-enough constrained to determine whether they are coeval with their southern counterparts. Earthquake W (∼850 cal BP), appears to be present in the northern Cascadia paleoseismic record, but yields considerably older ages than in central Cascadia, and may be missing from southernmost Cascadia. The onshore record of an offshore turbidite (T2) displays a similar spatio-temporal pattern to that of earthquake W.

  12. Line tension at lipid phase boundaries as driving force for HIV fusion peptide-mediated fusion

    Science.gov (United States)

    Yang, Sung-Tae; Kiessling, Volker; Tamm, Lukas K.

    2016-04-01

    Lipids and proteins are organized in cellular membranes in clusters, often called `lipid rafts'. Although raft-constituent ordered lipid domains are thought to be energetically unfavourable for membrane fusion, rafts have long been implicated in many biological fusion processes. For the case of HIV gp41-mediated membrane fusion, this apparent contradiction can be resolved by recognizing that the interfaces between ordered and disordered lipid domains are the predominant sites of fusion. Here we show that line tension at lipid domain boundaries contributes significant energy to drive gp41-fusion peptide-mediated fusion. This energy, which depends on the hydrophobic mismatch between ordered and disordered lipid domains, may contribute tens of kBT to fusion, that is, it is comparable to the energy required to form a lipid stalk intermediate. Line-active compounds such as vitamin E lower line tension in inhomogeneous membranes, thereby inhibit membrane fusion, and thus may be useful natural viral entry inhibitors.

  13. Determination of Minimised Kt Values and Boundary Shapes for a Class of Quasi-Rectangular Holes in Infinite Plates

    Science.gov (United States)

    2015-07-01

    September, San Francisco , USA. Heller M, Burchill M, Wescott R, Waldman W, Kaye R, Evans R, McDonald M, 2009: Airframe life extension by optimised...Waldman AUSTRALIA DEFENCE ORGANISATION No. of Copies Task Sponsor OIC- ASI -DGTA 1 S&T Program Air Force Scientific Adviser 1 Navy...AIR 07/283 10. TASK SPONSOR OIC- ASI -DGTA 11. NO. OF PAGES 50 12. NO. OF REFERENCES 25 13. DST GROUP PUBLICATIONS REPOSITORY http

  14. Evaluation of force plate-less estimation of the trajectory of the centre of pressure during gait. Comparison of two anthropometric models.

    Science.gov (United States)

    Pillet, Hélène; Bonnet, Xavier; Lavaste, François; Skalli, Wafa

    2010-02-01

    The estimation of the trajectory of the centre of pressure during gait is possible without using force plate by modelling the whole body as a multi-segment chain. The kinematics and inertial parameters of each segment are necessary to determine the ground reaction forces and moments. The position of the centre of pressure can then be calculated at each frame of time. The objective of the study was to evaluate the accuracy of the estimation of the position of the centre of pressure during gait obtained without force plate data. Segment inertial parameters were determined using a proportional model and a geometric model. The modelling and calculations were computed for six volunteers and the estimated centres of pressure were compared to the centre of pressure measured using force plates considered as the gold standard. The estimation was better using the geometric model with an accuracy of 33 mm (4.1% of the peak-to-peak amplitude) on the longitudinal axis and 14.2 mm (12.9% of the peak-to-peak amplitude) on the lateral axis.

  15. Direct numerical simulation of K-type and H-type transitions to turbulence in a low Mach number flat plate boundary layer

    Science.gov (United States)

    Sayadi, Taraneh; Hamman, Curtis; Moin, Parviz

    2011-11-01

    Transition to turbulence via spatially evolving secondary instabilities in compressible, zero-pressure-gradient flat plate boundary layers is numerically simulated for both the Klebanoff K-type and Herbert H-type disturbances. The objective of this work is to evaluate the universality of the breakdown process between different routes through transition in wall-bounded shear flows. Each localized linear disturbance is amplified through weak non-linear instability that grows into lambda-vortices and then hairpin-shaped eddies with harmonic wavelength, which become less organized in the late-transitional regime once a fully populated spanwise turbulent energy spectrum is established. For the H-type transition, the computational domain extends from Rex =105 , where laminar blowing and suction excites the most unstable fundamental and a pair of oblique waves, to fully turbulent stage at Rex = 10 . 6 ×105 . The computational domain for the K-type transition extends to Rex = 9 . 6 ×105 . The computational algorithm employs fourth-order central differences with non-reflective numerical sponges along the external boundaries. For each case, the Mach number is 0.2. Supported by the PSAAP program of DoE, ANL and LLNL.

  16. 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

  17. Deep-rooted “thick skinned” model for the High Atlas Mountains (Morocco. Implications for the seismic Eurasia-Africa plate boundary region

    Directory of Open Access Journals (Sweden)

    Guiraud, M.

    2007-06-01

    Full Text Available Previous crustal models of the High Atlas suppose the existence of a mid-crustal detachment where all the surface thrusts merged and below which the lower crust was continuous. However, both seismic refraction data and gravity modeling detected a jump in crustal thickness between the High Atlas and the northern plains. Here we show that this rapid and vertical jump in the depth of Moho discontinuity suggests that a thrust fault may penetrate the lower crust and offset the Moho (deep-rooted “thick skinned” model. The distribution of Neogene and Quaternary volcanisms along and at the northern part of the High Atlas lineament can be related to the beginning of a partial continental subduction of the West African plate to the north underneath Moroccan microplate. Allowing from the complex problem of the plate boundary in the western zone of the Mediterranean, we propose to interpret the South-Atlasic fault zone as the actual northwestern boundary of the stable part of the African plate rather than the Azores-Gibraltar fault currently used.Los modelos geodinámicos existentes sobre la estructura profunda del alto Atlas suponen la existencia de un despegue medio-cortical donde convergen los cabalgamientos superficiales y bajo el cual la corteza inferior es continua. Los datos de sísmica de refracción y gravimetría, sin embargo, indican la existencia de una discontinuidad en el grosor de la corteza (profundidad del Moho bajo el Alto Atlas. En este artículo ponemos de manifiesto que este salto rápido en la profundidad del Moho puede ser causado por un cabalgamiento que penetra la corteza inferior, desplazando la base de la misma ("deeprooted thick skinned model". La distribución del volcanismo Neógeno y Cuaternario a lo largo de y al norte de la alineación del Alto Atlas pueden estar relacionados con el comienzo de una subducción continental parcial de la placa Africana occidental hacia el norte, bajo la microplaca marroquí. La expresi

  18. Refined Views of Strike-slip Fault Zones, Seismicity, and State of Stress Associated With the Pacific-North America Plate Boundary in Southern California

    Science.gov (United States)

    Hauksson, E.; Nicholson, C.; Shaw, J. H.; Plesch, A.; Shearer, P. M.; Sandwell, D. T.; Yang, W.

    2013-12-01

    The mostly strike-slip plate boundary in southern California is expressed as a system of late Quaternary faults or principal slip zones (PSZs), with numerous adjacent smaller slip surfaces. It is complex, even after large cumulative displacements, and consists of major fault systems with multi-stranded, non-planar fault geometry, including some in close proximity to each other. There are also secondary cross faults and low-angle detachments that interact with the PSZs accommodating main plate boundary motion. The loading of plate-tectonic strain causes the largest earthquakes along PSZs, moderate-sized events in their immediate vicinity, and small earthquakes across the whole region. We apply relocated earthquake and refined focal mechanism (1981-2013) catalogs, as well as other geophysical datasets to provide refined views of the 3D fault geometry of these active fault systems. To determine properties of individual fault zones, we measure the Euclidian distance from every hypocenter to the nearest PSZ. In addition, we assign crustal geophysical parameters such as heat flow value and shear or dilatation strain rates to each epicenter. We investigate seismogenic thickness and fault zone width as well as earthquake source processes. We find that the seismicity rate is a function of location, with the rate dying off exponentially with distance from the PSZ. About 80% of small earthquakes are located within 5 km of a PSZ. For small earthquakes, stress drops increase in size with distance away from the PSZs. The magnitude distribution near the PSZs suggests that large earthquakes are more common close to PSZs, and they are more likely to occur at greater depth than small earthquakes. In contrast, small quakes can occur at any geographical location. An optimal combination of heat flow and strain rate is required to concentrate the strain along rheologically weak fault zones, which accommodate the crustal deformation processes, causing seismicity. The regional trend of

  19. One dimension spring supported ball on top of a sinusoidal vibrating plate: A forced oscillation simulation using molecular dynamics method

    CERN Document Server

    Viridi, Sparisoma; Hidayat, Wahyu; Singarimbun, Alamta; Balkis, Sitti

    2011-01-01

    A ball supported by a spring is set on top of a plate which is sinusoidal vibrated. The motion is limited to one dimension motion. It is assumed that the spring is an ideal one with zero mass. The vibrating plate is considered much heavier than the ball, so that the ball motion has no influence on the plate motion. Plate vibration frequency is varied around the frequency of ball-spring system. Resonance phenomenon is reported, which needs a phase match condition to occur.

  20. 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

  1. 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

  2. Climate response to orbital forcing across the Oligocene-Miocene boundary.

    Science.gov (United States)

    Zachos, J C; Shackleton, N J; Revenaugh, J S; Pälike, H; Flower, B P

    2001-04-13

    Spectral analyses of an uninterrupted 5.5-million-year (My)-long chronology of late Oligocene-early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power in climate is recorded at the 406-thousand-year (ky) period eccentricity band over a 3.4-million-year period [20 to 23.4 My ago (Ma)] as well as in the 125- and 95-ky bands over a 1.3-million-year period (21.7 to 23.0 Ma) of suspected low greenhouse gas levels. Moreover, a major transient glaciation at the epoch boundary ( approximately 23 Ma), Mi-1, corresponds with a rare orbital congruence involving obliquity and eccentricity. The anomaly, which consists of low-amplitude variance in obliquity (a node) and a minimum in eccentricity, results in an extended period ( approximately 200 ky) of low seasonality orbits favorable to ice-sheet expansion on Antarctica.

  3. Vacuum Energy and Casimir Force in a Presence of Skin-depth Dependent Boundary Condition

    CERN Document Server

    Lebedev, S L

    2001-01-01

    The vacuum energy-momentum tensor (EMT) and the vacuum energy corresponding to massive scalar field on $\\Re_{t}\\times [0,l] \\times \\Re^{D-2}$ space-time with boundary condition involving a dimensional parameter ($\\delta$) are found. The dependent on the cavity size $l$ Casimir energy $\\wt E_{C}$ is a uniquely determinable function of mass $m$, size $l$ and "skin-depth" $\\delta$. This energy includes the "bulk" and the surface (potential energy) contributions. The latter dominates when $l \\sim \\delta$. Taking the surface potential energy into account is crucial for the coincidence between the derivative $-\\d \\wt E_{C}/\\d l$ and the $ll$-component of the vacuum EMT. Casimir energy $\\wt E_C$ and the bulk contribution to it are interconnected through Legendre transformation, in which the quantity $\\delta^{-1}$ is conjugate to the vacuum surface energy multiplied by $\\delta$. The surface singularities of the vacuum EMT do not depend on $l$ and, for even $D$, $\\delta =0$ or $\\infty$, possess finite interpretation. ...

  4. Micro-acting Force in Boundary Layer in Low-Permeability Porous Media

    Institute of Scientific and Technical Information of China (English)

    FENG Yu-Liang; ZHANG Yuan; JI Bing-Yu; MU Wen-Zhi

    2011-01-01

    There are lots of reasons to restrict a low-permeability oil layer to enhance the recovery factor.Based on the research results of non-Darcy flow, microflow of water drive and micro-acting force in low permeability porous media are studied by establishing the expression of fluid viscosity factor.Numerical calculation shows that under the condition of L/S interaction, the radial velocity distribution near the solid wall changes obviously, and the curve form changes from convex to concave.The tinier the capillary radius is, the stronger the L/S interaction is.The larger the n value is, more obvionsly the flowing velocity decreases.The results will help people to deal with improving recovery factor of low permeability reservoir, and understanding the fluid flow behavior in blood capillary.%@@ There are lots of reasons to restrict a low-permeability oil layer to enhance the recovery factor.Based on the research results of non-Darcy flow, microfiow of water drive and micro-acting force in low permeability porous media are studied by establishing the expression of fluid viscosity factor.Numerical calculation shows that under the condition of L/S interaction, the radial velocity distribution near the solid wall changes obviously, and the curv