Science.gov

Sample records for hydrostatic two-layer flow

  1. Linear and nonlinear properties of reduced two-layer models for non-hydrostatic free-surface flow

    NASA Astrophysics Data System (ADS)

    Bai, Yefei; Cheung, Kwok Fai

    2016-11-01

    A two-layer model with uniform non-hydrostatic pressure in the bottom produces favorable dispersion properties for coastal wave transformation at the computational requirements of a one-layer model. We derive the nonlinear governing equations and the corresponding dispersion relation, shoaling gradient, and super- and sub-harmonics to understand the theoretical performance of this reduced model. With the layer interface near the bottom, the dispersion relation shows an extended applicable range into deeper water at the expense of a slight overestimation of the celerity in intermediate water depth. The shoaling gradient rapidly converges to the exact solution in the shallow and intermediate depth range. These complementary characteristics allow identification of an optimal interface position for both linear wave properties. The resulting model exhibits good nonlinear performance in shallow and intermediate water depth and produces super- and sub-harmonics comparable to a two-layer model. Numerical tests involving standing waves show the reduced model has smaller discretization errors in the dispersion relation comparing to a one-layer model. Case studies of regular wave transformation over a submerged bar and a uniform slope provide comparison with laboratory data and demonstrate the linear and nonlinear properties derived from the governing equations. The good shoaling and nonlinear properties give rise to accurate waveforms in both cases, while dispersion errors from the governing equations and numerical schemes accumulate over time leading to phase shifts of the modeled waves.

  2. Mixing and recirculation in two-layer exchange flows

    NASA Astrophysics Data System (ADS)

    StenströM, Petter

    2003-08-01

    Mixing and recirculation due to interfacial friction in two-layer exchange flows through topographic constrictions are investigated using a nonhydrostatic, three-dimensional numerical model. The simulated exchange flows are always lower than what inviscid hydraulic theory predicts; the reduction is greater for a contraction than for a sill, with intermediate values for sill-contraction combinations. A large fraction of a tracer flux in one layer is lost to the other layer from an inflow section at the entrance of the contraction (foot of the sill) up to the throat of the contraction (sill crest). For a contraction this fraction is about equal for the two layers, whereas for a sill the loss from the upper to the lower layer is about 6 times as high as the loss from the lower to the upper layer. Sill-contraction combinations show similar behavior to a contraction toward the dense reservoir and to a sill toward the light reservoir. The variation in recirculation fractions over a tidal cycle is small for flow over a sill, but greater for flow through a contraction. The peak rate of loss from a layer occurs when the flow in the other layer has its maximum, i.e., at maximum negative barotropic flow for the lower layer and at maximum positive barotropic flow for the upper layer.

  3. Vortex Stability In Two -layer Rotating Shallow-water Flows

    NASA Astrophysics Data System (ADS)

    Carton, Xavier; Baey, Jean-Michel

    The stability of circular vortices subject to an initial normal-mode perturbation is studied in a two-layer shallow-water fluid with rigid lid, flat bottom and constant background rotation. Considerable similarity with quasi-geostrophic dynamics is found for linear (barotropic or baroclinic) instability, except in the frontal and nonlinear barotropic limits. This discrepancy is explained by asymptotic models. In many cases, the elliptical mode of deformation is the most unstable one. The ability of these perturbed circular vortices to stabilize nonlinearly as long-lived multipoles is then investigated. For elliptical perturbations, steady tripoles form from moderately unstable vortices as in the quasi-geostrophic limit. These tripoles, which exhibit various 3D structures, are robust when perturbed by non coherent disturbances. More unstable circular vortices break as two dipoles, propagating in opposite directions. Triangular perturbations can also lead to stationary quadrupoles or to dipolar breaking. The similarity with quasi-geostrophic dynamics, which ext ends to these nonlinear regimes, is related to the weakness of the divergent circulation, as shown by the analysis of the Lighthill equation. J.M. Baey &X. Carton, 2001: "Piecewise-constant vortices in a two-layer shallow - water flow". Advances in mathematical modelling of atmosphere and ocean dynamics, Kluwer Acad. Publ., 61, p.87-92. J.M. Baey &X. Carton, 2002: "Vortex multipoles in two-layer rotating shallow -water flows". To appear in J. Fluid Mech.

  4. A compressible two-layer model for transient gas-liquid flows in pipes

    NASA Astrophysics Data System (ADS)

    Demay, Charles; Hérard, Jean-Marc

    2017-03-01

    This work is dedicated to the modeling of gas-liquid flows in pipes. As a first step, a new two-layer model is proposed to deal with the stratified regime. The starting point is the isentropic Euler set of equations for each phase where the classical hydrostatic assumption is made for the liquid. The main difference with the models issued from the classical literature is that the liquid as well as the gas is assumed compressible. In that framework, an averaging process results in a five-equation system where the hydrostatic constraint has been used to define the interfacial pressure. Closure laws for the interfacial velocity and source terms such as mass and momentum transfer are provided following an entropy inequality. The resulting model is hyperbolic with non-conservative terms. Therefore, regarding the homogeneous part of the system, the definition and uniqueness of jump conditions is studied carefully and acquired. The nature of characteristic fields and the corresponding Riemann invariants are also detailed. Thus, one may build analytical solutions for the Riemann problem. In addition, positivity is obtained for heights and densities. The overall derivation deals with gas-liquid flows through rectangular channels, circular pipes with variable cross section and includes vapor-liquid flows.

  5. Ultraefficient reduced model for countercurrent two-layer flows

    NASA Astrophysics Data System (ADS)

    Lavalle, Gianluca; Vila, Jean-Paul; Lucquiaud, Mathieu; Valluri, Prashant

    2017-01-01

    We investigate the dynamics of two superposed layers with density contrast flowing countercurrent inside a channel, when the lower layer is much thinner than the wavelength of interfacial waves. We apply a low-dimensional film model to the bottom (heavier) layer and introduce a fast and efficient method to predict the onset of flow reversal in this phase. We study three vertical scenarios with different applied pressure gradients and compare the temporal growth rates of linear and weakly nonlinear waves to the Orr-Sommerfeld problem and to the weakly nonlinear theory, respectively. At the loading point, i.e., when a large wave hump stands at the interface, our spatiotemporal analysis shows that the system is absolutely unstable. We then present profiles of nonlinear saturated waves, pressure field, and streamline distribution in agreement with direct numerical simulation. The reduced model presented here allows us to explore the effect of the upper-layer speed on the wave pattern, showing that the wave profile is very sensitive when the mean film thickness, rather than the liquid flow rate, is maintained constant in the simulation. In addition, we show the strong effect of surface tension on both the maximum wave hump and the crest steepness before the loading point. Finally, we reveal how the nonlinear wave speed affects the vortex distribution within the lower layer by analyzing the stream function under different scenarios.

  6. Two-layer flow of polymer melts in extruder die channel

    NASA Astrophysics Data System (ADS)

    Sharafutdinov, R. F.; Snigerev, B. A.; Galimov, E. R.; Galimova, N. Ya

    2016-06-01

    The paper discusses numerical modeling of two-layer flow of viscous non-Newtonian fluids in extruder die channels. Fluid motion is described by mass and momentum conservation equations supplemented by the rheological equation of state of a viscous non-Newtonian fluid according to the Carreau model. Technique of numerical solution of the problem based on the finite element method is presented. Distribution pattern of fluid velocities, pressure, stresses, positions of the interface in the two-layer flow depending on the rheological properties of a fluid and flow regimes is investigated.

  7. Development of an algebraic stress/two-layer model for calculating thrust chamber flow fields

    NASA Astrophysics Data System (ADS)

    Chen, C. P.; Shang, H. M.; Huang, J.

    1993-07-01

    Following the consensus of a workshop in Turbulence Modeling for Liquid Rocket Thrust Chambers, the current effort was undertaken to study the effects of second-order closure on the predictions of thermochemical flow fields. To reduce the instability and computational intensity of the full second-order Reynolds Stress Model, an Algebraic Stress Model (ASM) coupled with a two-layer near wall treatment was developed. Various test problems, including the compressible boundary layer with adiabatic and cooled walls, recirculating flows, swirling flows and the entire SSME nozzle flow were studied to assess the performance of the current model. Detailed calculations for the SSME exit wall flow around the nozzle manifold were executed. As to the overall flow predictions, the ASM removes another assumption for appropriate comparison with experimental data, to account for the non-isotropic turbulence effects.

  8. Development of an algebraic stress/two-layer model for calculating thrust chamber flow fields

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Shang, H. M.; Huang, J.

    1993-01-01

    Following the consensus of a workshop in Turbulence Modeling for Liquid Rocket Thrust Chambers, the current effort was undertaken to study the effects of second-order closure on the predictions of thermochemical flow fields. To reduce the instability and computational intensity of the full second-order Reynolds Stress Model, an Algebraic Stress Model (ASM) coupled with a two-layer near wall treatment was developed. Various test problems, including the compressible boundary layer with adiabatic and cooled walls, recirculating flows, swirling flows and the entire SSME nozzle flow were studied to assess the performance of the current model. Detailed calculations for the SSME exit wall flow around the nozzle manifold were executed. As to the overall flow predictions, the ASM removes another assumption for appropriate comparison with experimental data, to account for the non-isotropic turbulence effects.

  9. Flows induced by sorption on fibrous material in a two-layer oil-water system

    NASA Astrophysics Data System (ADS)

    Chaplina, T. O.; Chashechkin, Yu. D.; Stepanova, E. V.

    2016-09-01

    The processes of sorption on fibrous materials in the open elliptic cell filled with a two-layer oil-water liquid at rest are investigated experimentally. When the sorption efficiency dependent on the type of material proves to be reasonably high, large-scale flows are formed in the liquid. In this case, the uniformity of distribution of oil is violated and the free surface of the water is partially restored. The trajectories of motion of individual oil droplets on a released water surface are tracked, and the transfer rates are calculated in various phases of the process.

  10. Baroclinic two-layer flow induced by extreme discharge from a dam in a narrow channel

    NASA Astrophysics Data System (ADS)

    Kwak, Myeong-Taek; Seo, Gwang-Ho; Cho, Yang-Ki; Cho, Chang-Woo; Choo, Hyo-Sang; Yoon, Yang-Ho; Kim, Jong-Kyu; Jung, Kyung Tae

    2014-12-01

    Long-term current observations were taken in the narrow Noryang Channel during extreme discharge and small discharge periods from a river dam. The Noryang Channel connects the west Gwangyang and east Jinju bays in southern Korea. Jinju Bay is relatively isolated from the open sea by many islands, whereas Gwangyang Bay is connected to the open sea through a wide, deep channel. Jinju Bay is closer to the river dam than Gwangyang Bay. The residual mean flow in the channel over the observation period showed a baroclinic two-layer flow as in an estuary during the large discharge period, whereas barotropic flow was present during the small discharge period. During the large discharge period, the upper layer of water flowed continuously westward, whereas the lower layer flowed eastward. Hydrographic data observed along the channel showed that Gwangyang Bay water was relatively saline and heavier during the large discharge period. This spatial difference in water density might be the result of a large inflow of discharge into Jinju Bay and relatively strong mixing between the water in Gwangyang Bay and the open sea. The salinity in the more isolated Jinju Bay was lower. Simple analytical model calculations showed that horizontal density difference during the large discharge period could drive the surface current flow westward, whereas that of the dense water of the lower layer in Gwangyang Bay flowed eastward through the Noryang Channel.

  11. Three-dimensional convective and absolute instabilities in pressure-driven two-layer channel flow

    NASA Astrophysics Data System (ADS)

    Sahu, Kirti; Matar, Omar

    2011-11-01

    A generalized linear stability analysis of three-dimensional disturbance in a pressure-driven two-layer channel flow, focusing on the range of parameters for which Squire's theorem does not exist is considered. Three-dimensional linear stability equations, in which both the spatial wavenumber and temporal frequency are complex, are derived and solved using an efficient spectral collocation method. A Briggs-type analysis is then carried out to delineate the boundaries between convective and absolute instabilities in m-Re space. We find that although three-dimensional disturbances are temporally more unstable than the two-dimensional disturbances, absolute modes of instability are most unstable for two-dimensional disturbances. An energy ``budget'' analysis also shows that the most dangerous modes are ``interfacial'' ones.

  12. Two-layer interfacial flows beyond the Boussinesq approximation: a Hamiltonian approach

    NASA Astrophysics Data System (ADS)

    Camassa, R.; Falqui, G.; Ortenzi, G.

    2017-02-01

    The theory of integrable systems of Hamiltonian PDEs and their near-integrable deformations is used to study evolution equations resulting from vertical-averages of the Euler system for two-layer stratified flows in an infinite two-dimensional channel. The Hamiltonian structure of the averaged equations is obtained directly from that of the Euler equations through the process of Hamiltonian reduction. Long-wave asymptotics together with the Boussinesq approximation of neglecting the fluids’ inertia is then applied to reduce the leading order vertically averaged equations to the shallow-water Airy system, albeit in a non-trivial way. The full non-Boussinesq system for the dispersionless limit can then be viewed as a deformation of this well known equation. In a perturbative study of this deformation, a family of approximate constants of the motion are explicitly constructed and used to find local solutions of the evolution equations by means of hodograph-like formulae.

  13. Hydrostatics and steady dynamics of spatially varying electromechanical flow structures

    NASA Technical Reports Server (NTRS)

    Jones, T. B.

    1974-01-01

    The hydrostatic and steady laminar hydrodynamic equilibria of spatially varying electromechanical flow structures are investigated. Under certain conditions the relationship between the dielectric height of rise and the applied voltage is found to be double valued. It is found that one of the two equilibrium values is always unstable. This gives rise to the experimentally observed spontaneous rise of the fluid to the top of the structure, once a certain critical voltage is reached. Starting above this critical voltage with the structure completely filled and decreasing the applied voltage toward the critical value results in pinch-in failure at an intermediate point along the structure and trapping of dielectric fluid at the top. The simple mathematical model developed predicts all these phenomena, without recourse to tedious point-by-point surface force equilibrium determination. Experiments are reported which verify the results for the hydrostatic case.

  14. Global chaotization of fluid particle trajectories in a sheared two-layer two-vortex flow.

    PubMed

    Ryzhov, Evgeny A; Koshel, Konstantin V

    2015-10-01

    In a two-layer quasi-geostrophic approximation, we study the irregular dynamics of fluid particles arising due to two interacting point vortices embedded in a deformation flow consisting of shear and rotational components. The two vortices are arranged within the bottom layer, but an emphasis is on the upper-layer fluid particle motion. Vortices moving in one layer induce stirring of passive scalars in the other layer. This is of interest since point vortices induce singular velocity fields in the layer they belong to; however, in the other layer, they induce regular velocity fields that generally result in a change in passive particle stirring. If the vortices are located at stagnation points, there are three different types of the fluid flow. We examine how properties of each flow configuration are modified if the vortices are displaced from the stagnation points and thus circulate in the immediate vicinity of these points. To that end, an analysis of the steady-state configurations is presented with an emphasis on the frequencies of fluid particle oscillations about the elliptic stagnation points. Asymptotic relations for the vortex and fluid particle zero-oscillation frequencies are derived in the vicinity of the corresponding elliptic points. By comparing the frequencies of fluid particles with the ones of the vortices, relations between the parameters that lead to enhanced stirring of fluid particles are established. It is also demonstrated that, if the central critical point is elliptic, then the fluid particle trajectories in its immediate vicinity are mostly stable making it harder for the vortex perturbation to induce stirring. Change in the type of the central point to a hyperbolic one enhances drastically the size of the chaotic dynamics region. Conditions on the type of the central critical point also ensue from the derived asymptotic relations.

  15. Global chaotization of fluid particle trajectories in a sheared two-layer two-vortex flow

    SciTech Connect

    Ryzhov, Evgeny A.; Koshel, Konstantin V.

    2015-10-15

    In a two-layer quasi-geostrophic approximation, we study the irregular dynamics of fluid particles arising due to two interacting point vortices embedded in a deformation flow consisting of shear and rotational components. The two vortices are arranged within the bottom layer, but an emphasis is on the upper-layer fluid particle motion. Vortices moving in one layer induce stirring of passive scalars in the other layer. This is of interest since point vortices induce singular velocity fields in the layer they belong to; however, in the other layer, they induce regular velocity fields that generally result in a change in passive particle stirring. If the vortices are located at stagnation points, there are three different types of the fluid flow. We examine how properties of each flow configuration are modified if the vortices are displaced from the stagnation points and thus circulate in the immediate vicinity of these points. To that end, an analysis of the steady-state configurations is presented with an emphasis on the frequencies of fluid particle oscillations about the elliptic stagnation points. Asymptotic relations for the vortex and fluid particle zero–oscillation frequencies are derived in the vicinity of the corresponding elliptic points. By comparing the frequencies of fluid particles with the ones of the vortices, relations between the parameters that lead to enhanced stirring of fluid particles are established. It is also demonstrated that, if the central critical point is elliptic, then the fluid particle trajectories in its immediate vicinity are mostly stable making it harder for the vortex perturbation to induce stirring. Change in the type of the central point to a hyperbolic one enhances drastically the size of the chaotic dynamics region. Conditions on the type of the central critical point also ensue from the derived asymptotic relations.

  16. Gravity current flow over sinusoidal topography in a two-layer ambient

    NASA Astrophysics Data System (ADS)

    Nicholson, Mitchell; Flynn, Morris R.

    2015-09-01

    We report upon a laboratory experimental study of dense full- and partial-depth locks released gravity currents propagating through a two-layer ambient and over sinusoidal topography of amplitude A and wavelength λ. Attention is restricted to a Boussinesq flow regime and the initial (or slumping) stage of motion. Because of the presence of the topography, the lower layer depth and channel depth vary in the downstream direction by as much as ±52% and ±40%, respectively. Despite such large variations, the instantaneous gravity current front speed typically changes by only a small amount from its average value, U ¯ . We conclude that the reason for this unexpected observation is a counterbalancing between the contraction/expansion of the channel on one hand and along-slope variations of the buoyancy force on the other hand. Compared to the case of gravity current flow over a horizontal surface, the topography has a retarding effect on U ¯ ; we characterize the variation of U ¯ with the following parameters: A, A/λ, the interface height, the height of gravity current fluid inside the lock, and the layer densities as characterized by S ≡ (ρ1 - ρ2)/(ρ0 - ρ2) where ρ0 is the gravity current density, ρ1 is the lower ambient layer density, and ρ2 is the upper ambient layer density. The topography also alters the structure of the gravity current head by inducing large-scale Kelvin-Helmholtz (K-H) vortices directly downstream of regions of significant shear. These vortices are transient flow features; after formation and saturation, they relax at which point gravity current fluid sloshes back and forth in the topographic troughs. A simple geometric model is presented that prescribes the minimum number of topographic peaks a gravity current fluid will overcome. As in the horizontal bottom case, the forward advance of the gravity current can excite a downstream-propagating interfacial disturbance, which is more prominent for larger S. We identify when the

  17. Resonance phenomena in a two-layer two-vortex shear flow

    NASA Astrophysics Data System (ADS)

    Ryzhov, Eugene A.; Koshel, Konstantin V.

    2016-11-01

    The paper deals with a dynamical system governing the motion of two point vortices embedded in the bottom layer of a two-layer rotating flow experiencing linear deformation and their influence on fluid particle advection. The linear deformation consists of shear and rotational components. If the deformation is stationary, the vortices can move periodically in a bounded region. The vortex periodic motion induces stirring patterns of passive fluid particles in the both layers. We focus our attention on the upper layer where the bottom-layer singular point vortices induce a regular velocity field with no singularities. In the upper layer, we determine a steady-state regime featuring no closed fluid particle trajectories associated with the vortex motion. Thus, in the upper layer, the flow's streamlines look like there is only external linear deformation and no vortices. In this case, fluid particles move along trajectories of almost regular elliptic shapes. However, the system dynamics changes drastically if the underlying vortices cease to be stationary and instead start moving periodically generating a nonstationary perturbation for the fluid particle advection. Then, we demonstrate that this steady-state regime transits to a perturbed state with a rich phase portrait structure featuring both periodic and chaotic fluid particle trajectories. Thus, the perturbed state clearly manifests the impact of the underlying vortex motion. An analysis, based on comparing the eigenfrequencies of the steady-state fluid particle rotation with the ones of the vortex rotation, is carried out, and parameters ensuring effective fluid particle stirring are determined. The process of separatrix reconnection of close stability islands leading to an enhanced chaotic region is reported and analyzed.

  18. Resonance phenomena in a two-layer two-vortex shear flow.

    PubMed

    Ryzhov, Eugene A; Koshel, Konstantin V

    2016-11-01

    The paper deals with a dynamical system governing the motion of two point vortices embedded in the bottom layer of a two-layer rotating flow experiencing linear deformation and their influence on fluid particle advection. The linear deformation consists of shear and rotational components. If the deformation is stationary, the vortices can move periodically in a bounded region. The vortex periodic motion induces stirring patterns of passive fluid particles in the both layers. We focus our attention on the upper layer where the bottom-layer singular point vortices induce a regular velocity field with no singularities. In the upper layer, we determine a steady-state regime featuring no closed fluid particle trajectories associated with the vortex motion. Thus, in the upper layer, the flow's streamlines look like there is only external linear deformation and no vortices. In this case, fluid particles move along trajectories of almost regular elliptic shapes. However, the system dynamics changes drastically if the underlying vortices cease to be stationary and instead start moving periodically generating a nonstationary perturbation for the fluid particle advection. Then, we demonstrate that this steady-state regime transits to a perturbed state with a rich phase portrait structure featuring both periodic and chaotic fluid particle trajectories. Thus, the perturbed state clearly manifests the impact of the underlying vortex motion. An analysis, based on comparing the eigenfrequencies of the steady-state fluid particle rotation with the ones of the vortex rotation, is carried out, and parameters ensuring effective fluid particle stirring are determined. The process of separatrix reconnection of close stability islands leading to an enhanced chaotic region is reported and analyzed.

  19. Planetary-Scale Flow on a Two-Layer Beta-Plane Channel Model with Topography

    NASA Astrophysics Data System (ADS)

    Shin, Won-Tae Kwon

    A two-layer low-order spectral model on a beta-plane channel with topographic, thermal and frictional forcing is designed as a compromise to resolve the relative importance and interaction of several relevant processes. The model is truncated at three zonal modes and three meridional modes. Topography forces the largest scale; the intermediate scale may be destabilized by zonal thermal forcing; the smallest scale permits barotropic scale-interaction and a rudimentary energy cascade. Multiple steady states of the simple one zonal mode and one wave mode (the 1 x 1 model) have been found. There are seven possible steady states: a zonally symmetric state, a topographically resonant state, and five baroclinic and equivalent barotropic wave states. New results emphasize relevance of the barotropic and baroclinic zonal flows; most significantly, multiple steady states exist only for a restricted range of zonal wind and vertical shear in the vicinity of the topographically resonant values. The time-dependent behavior for the 3 x 3 model is classified into six different types: zonally symmetric, steady wave state, steady propagating (Rossby wave), periodic, quasi-periodic and chaotic solutions. The regimes of the solutions for three parameters (thermal forcing, topography and friction) are investigated. The amplitude of zonal flow in wave solutions is weaker with moderate topography and is stronger with larger friction, smaller thermal forcing and higher topography or no topography. The characteristics of solutions are related to the strength of the resultant zonal flow with small or moderate topography. When the intermediate scale wave with largest meridional scale (MODE 12) is baroclinically unstable, this wave maintains the topographic wave ridge upstream of the mountain through the wave-wave interaction and also maintains other waves through form-drag; then, other modes are maintained by various mechanisms. When the topographic wave (MODE 11) becomes unstable with

  20. A conservative method for hydrostatic flow in isentropic coordinates

    NASA Astrophysics Data System (ADS)

    Peeters, B.; Bokhove, O.; Frank, J.

    2010-05-01

    Although our climate is ultimately driven by (nonuniform) solar heating, many aspects of the flow can be understood qualitatively from forcing-free and frictionless dynamics. In the limit of zero forcing and dissipation, our weather system falls under the realm of Hamiltonian fluid dynamics and the flow conserves potential vorticity (PV), energy and phase-space structure. We have found a conservative numerical scheme for a hydrostatic atmosphere based on a mixed Eulerian-Lagrangian approach, the so-called parcel formulation [1]. For adiabatic flow, the entropy is materially conserved. Under stable stratifications, we introduce isentropic coordinates to simplify the governing equations. The entropic direction is discretized using finite elements. The discretization of horizontal Lagrangian label space (from infinitesimal fluid parcels to discrete fluid particles) yields a discrete Poisson bracket. New is that we apply the Hamiltonian Particle-Mesh method [2], and view the potential as an Eulerian function, reconstructed from the particle data. The use of an Eulerian grid makes the method more efficient and stable. The Hamiltonian consists of a Lagrangian kinetic energy and an Eulerian potential energy. The discrete system of ODE's is thus a Hamiltonian system conserving mass, PV, energy and phase-space structure. If we incorporate a symplectic time integrator, the resulting fully discrete system conserves energy approximately without any drift in energy. Several challenging (nonlinear) solutions will be tested, such a flow over a rising bump. Also, preliminary results for bottom-intersecting isentropes will be demonstrated. REFERENCES [1] O. Bokhove and M. Oliver, Parcel Eulerian-Lagrangian fluid dynamics for rotating geophysical flows, Proc. Roy. Soc. A. 462, pp. 2563-2573 (2006) [2] J. Frank, G. Gottwald, S. Reich, A Hamiltonian particle-mesh method for the rotating shallow-water equations, Lecture Notes in Computational Science and Engineering, Vol. 26, Springer

  1. Numerical and Analytical Study of Two-Layered Unsteady Blood Flow through Catheterized Artery

    PubMed Central

    Zaman, Akbar; Ali, Nasir; Sajid, M.; Hayat, Tasawar

    2016-01-01

    The pulsatile flow of blood in a catheterized blood vessel is analyzed. The flow of blood in vessel is modeled as the flow of two immiscible fluids. The fluid in the core region is characterized as a non-Newtonian viscoelastic fluid satisfying the constitutive equation of an Oldroyd-B fluid. The fluid in the peripheral region is treated as a Newtonian fluid. The catheter inside the vessel is modeled as a rigid tube of very small radius. The resulting differential system for velocity in each region is computed numerically by finite-difference scheme and analytically by Laplace transform. A comparison of numerical solution with Laplace transform solution is carried out. Various physical quantities of interest through the computed velocity are also analyzed. PMID:27548476

  2. Stability of two-layer Couette flow with application to drag reduction

    NASA Astrophysics Data System (ADS)

    Mohammadi, Alireza; Smits, Alexander J.

    2016-11-01

    We consider the linear stability of flows composed of two superposed fluids in Couette flow in order to improve our understanding of the longevity and performance of superhydrophobic surfaces (SHS) or liquid-infused surfaces (LIS) which are important for drag reduction. Here, we assume that the fluids are immiscible, incompressible, and Newtonian with constant properties. Single-fluid Couette flow is known to be linearly stable for any Reynolds number. However, inclusion of the second layer of fluid enriches the problem and introduces five new parameters: viscosity ratio, density ratio, thickness ratio, Froude number and Weber number. Two kinds of instability can appear: an unstable interfacial mode, and a Tollmein-Schlichting mode. In this work we parametrically study the flow stability with specific emphasis on the effects of viscosity ratio, interfacial tension, and thickness ratio. Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Office of Naval Research (ONR) through MURI Grants N00014-12-1-0875 and N00014-12-1-0962 (Program Manager Dr. Ki-Han Kim).

  3. A Numerical Study of Non-hydrostatic Shallow Flows in Open Channels

    NASA Astrophysics Data System (ADS)

    Zerihun, Yebegaeshet T.

    2017-06-01

    The flow field of many practical open channel flow problems, e.g. flow over natural bed forms or hydraulic structures, is characterised by curved streamlines that result in a non-hydrostatic pressure distribution. The essential vertical details of such a flow field need to be accounted for, so as to be able to treat the complex transition between hydrostatic and non-hydrostatic flow regimes. Apparently, the shallow-water equations, which assume a mild longitudinal slope and negligible vertical acceleration, are inappropriate to analyse these types of problems. Besides, most of the current Boussinesq-type models do not consider the effects of turbulence. A novel approach, stemming from the vertical integration of the Reynolds-averaged Navier-Stokes equations, is applied herein to develop a non-hydrostatic model which includes terms accounting for the effective stresses arising from the turbulent characteristics of the flow. The feasibility of the proposed model is examined by simulating flow situations that involve non-hydrostatic pressure and/or nonuniform velocity distributions. The computational results for free-surface and bed pressure profiles exhibit good correlations with experimental data, demonstrating that the present model is capable of simulating the salient features of free-surface flows over sharply-curved overflow structures and rigid-bed dunes.

  4. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, James R.

    1982-01-01

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  5. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1982-05-04

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion. 3 figs.

  6. Interfacial dynamics in pressure-driven two-layer laminar channel flow with high viscosity ratios.

    PubMed

    Matar, O K; Lawrence, C J; Sisoev, G M

    2007-05-01

    The large-scale dynamics of an interface separating two immiscible fluids in a channel is studied in the case of large viscosity contrasts. A long-wave analysis in conjunction with the Kármán-Polhausen method to approximate the velocity profile in the less viscous fluid is used to derive a single equation for the interface. This equation accounts for the presence of interfacial stress, capillarity, and viscous retardation as well as inertia in the less viscous fluid layer where the flow is considered to be quasistatic; the equation is shown to reduce to a Benney-type equation and the Kuramoto-Sivashinskiy equation in the relevant limits. The solutions of this equation are parametrized by an initial thickness ratio h0 and a dimensionless parameter S , which measures the relative significance of inertial to capillary forces. A parametric continuation technique is employed, which reveals that nonuniqueness of periodic solutions is possible in certain regions of (h0,S) space. Transient numerical simulations are also reported, whose results demonstrate good agreement with the bifurcation structure obtained from the parametric continuation results.

  7. Hydrostatic bearings for a turbine fluid flow metering device

    DOEpatents

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  8. A Semi-Hydrostatic Theory of Gravity-Dominated Compressible Flow

    NASA Astrophysics Data System (ADS)

    Dubos, T.; Voitus, F.

    2014-12-01

    Compressible Euler equations support the propagation of acoustic waves. Although much progress has been achieved towards efficient and accurate solutions to the resulting numerical difficulties, it can still be desirable to identify "unified" equations of motion that would not support acoustic waves while retaining accuracy at large and small scales. Even if such equations are eventually not chosen as the basis of a numerical model, they may help identifying the independent degrees of freedom of the atmospheric flow to be modeled and how the dependent fields are related to the independent fields. From Hamilton's least action principle (HP), "semi-hydrostatic" compressible equations of motion with density diagnosed from potential temperature through hydrostatic balance are derived. Energy, potential vorticity and momentum are conserved. Slaving density to potential temperature suppresses the degrees of freedom supporting the propagation of acoustic waves and results in a sound-proof system. Scale analysis and linear normal modes analysis for an isothermal state of rest suggest that the semy-hydrostatic system is accurate from hydrostatic to non-hydrostatic scales, except for deep internal gravity waves (Figure : decimal logarithm of relative error of the frequency of internal normal modes of a non-rotating isothermal atmosphere as a function of horizontal and vertical wavenumbers k,m normalized by the scale height H). Especially the Lamb wave and long Rossby waves are not distorted, unlike with anelastic or pseudo-incompressible systems. Compared to similar equations derived by Arakawa and Konor (2009), the semi-hydrostatic system possesses an additional term in the horizontal momentum budget. This term is an apparent force resulting from the vertical coordinate not being the actual height of an air parcel, but its hydrostatic height, i.e. the hypothetical height it would have after the atmospheric column it belongs to has reached hydrostatic balance through

  9. Study of an unitised bidirectional vanadium/air redox flow battery comprising a two-layered cathode

    NASA Astrophysics Data System (ADS)

    grosse Austing, Jan; Nunes Kirchner, Carolina; Hammer, Eva-Maria; Komsiyska, Lidiya; Wittstock, Gunther

    2015-01-01

    The performance of a unitised bidirectional vanadium/air redox flow battery (VARFB) is described. It contains a two-layered cathode consisting of a gas diffusion electrode (GDE) with Pt/C catalyst for discharging and of an IrO2 modified graphite felt for charging. A simple routine is shown for the modification of a graphite felt with IrO2. A maximum energy efficiency of 41.7% at a current density of 20 mA cm-2 as well as an average discharge power density of 34.6 mW cm-2 at 40 mA cm-2 were obtained for VARFB operation at room temperature with the novel cathode setup. A dynamic hydrogen electrode was used to monitor half cell potentials during operation allowing to quantify the contribution of the cathode to the overall performance of the VARFB. Four consecutive cycles revealed that crossover of vanadium ions took place and irreversible degradation processes within the reaction unit lead to a performance decrease.

  10. The effect of journal misalignment on the operation of a turbulent flow hydrostatic bearing

    NASA Astrophysics Data System (ADS)

    San Andres, Luis

    1993-07-01

    An analysis for calculation of the dynamic force and moment response in turbulent flow, orifice compensated hydrostatic journal bearings is presented. The fully developed flow of a barotropic liquid is described by variable properties, bulk-flow equations and local turbulent friction factors based on bearing surface condition. Bearing load and moments and, dynamic force and moment coefficients are calculated for perturbations in journal center displacements and misaligned journal axis rotations. Numerical results for the effect of static misalignment angles in the plane of the eccentricity vector are presented for a water lubricated hydrostatic bearing. The predictions show that journal axis misalignment causes a reduction in load capacity due to loss in film thickness, increases the flow rate and produces significant restoring moments (couples). Force and moment coefficients due to dynamic journal axis rotations are also discussed.

  11. Three-dimensional linear instability in pressure-driven two-layer channel flow of a Newtonian and a Herschel-Bulkley fluid

    NASA Astrophysics Data System (ADS)

    Sahu, K. C.; Matar, O. K.

    2010-11-01

    The three-dimensional linear stability characteristics of pressure-driven two-layer channel flow are considered, wherein a Newtonian fluid layer overlies a layer of a Herschel-Bulkley fluid. We focus on the parameter ranges for which Squire's theorem for the two-layer Newtonian problem does not exist. The modified Orr-Sommerfeld and Squire equations in each layer are derived and solved using an efficient spectral collocation method. Our results demonstrate the presence of three-dimensional instabilities for situations where the square root of the viscosity ratio is larger than the thickness ratio of the two layers; these "interfacial" mode instabilities are also present when density stratification is destabilizing. These results may be of particular interest to researchers studying the transient growth and nonlinear stability of two-fluid non-Newtonian flows. We also show that the "shear" modes, which are present at sufficiently large Reynolds numbers, are most unstable to two-dimensional disturbances.

  12. A theoretical, two-layer, reduced-gravity model for descending dense water flow on continental shelves/slopes

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Ikeda, Moto; Saucier, Francois J.

    2003-05-01

    A theoretical, two-layer, reduced-gravity model for descending dense water flow on continental shelves/slopes has been developed to investigate the dynamics of bottom dense water plumes. The model is nonsteady state and includes vertical viscosity, the Coriolis force, and bottom friction. An integral solution rather than a perfect analytical expression is derived and, thus, the Simpson's 1/3 rule to approximate the integral is applied. At the very bottom, the dense water plume moves about 45° to the right (left) in the Northern (Southern) Hemisphere, looking downslope. From the bottom, the velocity vector rotates anticyclonically upward, indicating a bottom Ekman spiral that mimics the atmospheric Ekman boundary layer. The dense water within the bottom Ekman layer obeys a three-force balance, while the dense water above the bottom Ekman layer is governed by a two-force balance, which is a geostrophic flow with superimposed cycloidal inertial oscillations oriented from about 25° to 140° to the right (left) of the downslope direction in the Northern (Southern) Hemisphere. The transport within the bottom Ekman layer is directed about 60-70° to the right (left) of the downslope direction in the Northern (Southern) Hemisphere, forming an offshore (cross-isobath) transport in the absence of eddy flux and wind-forcing. The ratio of offshore transport to alongshore transport within the bottom Ekman layer is about 0.19 (19%), while the ratio above the bottom Ekman layer (i.e., geostrophic layer of the dense water) is only 3% (negligible compared to its alongshore transport), which, however, is equivalent in magnitude to its counterpart in the bottom Ekman layer if O(DE/h) ˜ 0.1 (where DE is the bottom Ekman layer thickness and h is the dense water layer thickness). In other words, the bottom Ekman layer and the geostrophic (dense) layer contribute equivalent dense water offshore (each contributes 50%). The magnitude of the descending dense water velocity depends

  13. A two Layer Convecting Mantle With Exchange : A Unified Model Based on Geochemical, Seismic and Heat Flow Observations

    NASA Astrophysics Data System (ADS)

    Allègre, C. J.; Jaupart, C.; Nolet, G.

    2007-12-01

    -penetrating slabs as emphasized by Fukao and al.(2001) and the recent observation of the large energy spectrum differences at 670 km depth (Gu and al., 2006). We discuss the problem of return flow, which is crucial for both energy budget and convection regime. The recent work on plume by Montelli and al. (2004, 2006) shows the existence of broad plumes in the lower mantle and thin plumes in the upper mantle. d) The estimate of heat flow coming from the lower mantle of 35-32 TW. The work of Davies(1990) and Sleep(1992) shows clearly that this transfer is not the result of plumes reaching the surface, because they correspond at most to 3TW. At the reverse the estimated heat flow carried by the lower mantle plumes is much higher (Nolet and al., 2006). We also discuss the heat flow paradox to explain a Urey ratio of 0.4 with whole mantle convection. In conclusion, we propose mantle with two layers convecting separately but with some exchange of matter, this global exchange corresponding to 1.1024kg since 4.4 Gy. Plume genesis is a two-stage process. Lower mantle plumes heat the Mesosphere boundary layer generating second generation plumes which reach the surface (Allègre and Turcotte; 1983; Allègre, 1987). In the upper mantle itself, we have to distinguish between a vigorously convecting asthenosphere and a sluggish convecting transition zone, both convecting in same cells.

  14. Three-dimensional linear instability in pressure-driven two-layer channel flow of a Newtonian and a Herschel-Bulkley fluid

    NASA Astrophysics Data System (ADS)

    Sahu, Kirti; Matar, Omar

    2010-11-01

    We investigate the three-dimensional linear characteristics of pressure-driven two-layer channel flow, focussing on the range of parameters for which Squire's theorem does not exist, wherein a Newtonian fluid layer overlies a layer of a Herschel-Bulkley fluid. The modified Orr-Sommerfeld and Squire equations in each layers are derived and solved using an efficient spectral collocation method. Our results demonstrate the presence of three-dimensional instabilities for situations where the square root of the viscosity ratio is larger than the thickness ratio of the two layers; these "interfacial" mode instabilities are also present when density stratification is destabilising. These results may be of particular interest to researchers studying the transient growth and nonlinear stability of two-fluid flows. We also show that the "shear" modes, which are present at sufficiently large Reynolds numbers, are most unstable to two-dimensional disturbances.

  15. Three Dimensional Flow and Pressure Patterns in a Hydrostatic Journal Bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. Jack; Dzodzo, Milorad B.

    1996-01-01

    The flow in a hydrostatic journal bearing (HJB) is described by a mathematical model that uses the three dimensional non-orthogonal form of the Navier-Stokes equations. Using the u, v, w, and p, as primary variables, a conservative formulation, finite volume multi-block method is applied through a collocated, body fitted grid. The HJB has four shallow pockets with a depth/length ratio of 0.067. This paper represents a natural extension to the two and three dimensional studies undertaken prior to this project.

  16. Three Dimensional Flow and Pressure Patterns in a Hydrostatic Journal Bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. Jack; Dzodzo, Milorad B.

    1996-01-01

    The flow in a hydrostatic journal bearing (HJB) is described by a mathematical model that uses the three dimensional non-orthogonal form of the Navier-Stokes equations. Using the u, v, w, and p, as primary variables, a conservative formulation, finite volume multi-block method is applied through a collocated, body fitted grid. The HJB has four shallow pockets with a depth/length ratio of 0.067. This paper represents a natural extension to the two and three dimensional studies undertaken prior to this project.

  17. The effect of temperature on the boundary of polymer melts in the modeling of two-layers flow

    NASA Astrophysics Data System (ADS)

    Bondarenko, A. V.; Kozitsyna, M. V.; Trufanova, N. M.

    2016-10-01

    The article is devoted to determine the velocity fields, temperatures and boundary flows of bi layers of polymer coating when both of them are applied simultaneously. The mathematical model of the flow was developed using finite - elements method with was the part of Ansys Cfx software packet.

  18. Documentation of a finite-element two-layer model for simulation of ground-water flow

    USGS Publications Warehouse

    Mallory, Michael J.

    1979-01-01

    This report documents a finite-element model for simulation of ground-water flow in a two-aquifer system where the two aquifers are coupled by a leakage term that represents flow through a confining layer separating the two aquifers. The model was developed by Timothy J. Durbin (U.S. Geological Survey) for use in ground-water investigations in southern California. The documentation assumes that the reader is familiar with the physics of ground-water flow, numerical methods of solving partial-differential equations, and the FORTRAN IV computer language. It was prepared as part of the investigations made by the U.S. Geological Survey in cooperation with the San Bernardino Valley Municipal Water District. (Kosco-USGS)

  19. Three Dimensional Flow and Pressure Patterns in a Single Pocket of a Hydrostatic Journal Bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. Jack; Dzodzo, Milorad B.

    1996-01-01

    The flow in a hydrostatic pocket is described by a mathematical model that uses the three dimensional Navier-Stokes equations written in terms of the primary variables, u, v, w, and p. Using a conservative formulation, a finite volume multi-block method is applied through a collocated, body fitted grid. The flow is simulated in a shallow pocket with a depth/length ratio of 0.02. The flow structures obtained and described by the authors in their previous two dimensional models are made visible in their three dimensional aspect for the Couette flow. It has been found that the flow regimes formed central and secondary vortical cells with three dimensional corkscrew-like structures that lead the fluid on an outward bound path in the axial direction of the pocket. The position of the central vortical cell center is at the exit region of the capillary restrictor feedline. It has also been determined that a fluid turn around zone occupies all the upstream space between the floor of the pocket and the runner, thus preventing any flow exit through the upstream port. The corresponding pressure distribution under the shaft presented as well. It was clearly established that for the Couette dominated case the pressure varies significantly in the pocket in the circumferential direction, while its variation is less pronounced axially.

  20. Three Dimensional Flow and Pressure Patterns in a Single Pocket of a Hydrostatic Journal Bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. Jack; Dzodzo, Milorad B.

    1996-01-01

    The flow in a hydrostatic pocket is described by a mathematical model that uses the three dimensional Navier-Stokes equations written in terms of the primary variables, u, v, w, and p. Using a conservative formulation, a finite volume multi-block method is applied through a collocated, body fitted grid. The flow is simulated in a shallow pocket with a depth/length ratio of 0.02. The flow structures obtained and described by the authors in their previous two dimensional models are made visible in their three dimensional aspect for the Couette flow. It has been found that the flow regimes formed central and secondary vortical cells with three dimensional corkscrew-like structures that lead the fluid on an outward bound path in the axial direction of the pocket. The position of the central vortical cell center is at the exit region of the capillary restrictor feedline. It has also been determined that a fluid turn around zone occupies all the upstream space between the floor of the pocket and the runner, thus preventing any flow exit through the upstream port. The corresponding pressure distribution under the shaft presented as well. It was clearly established that for the Couette dominated case the pressure varies significantly in the pocket in the circumferential direction, while its variation is less pronounced axially.

  1. Linear and nonlinear instability and ligament dynamics in 3D laminar two-layer liquid/liquid flows

    NASA Astrophysics Data System (ADS)

    Ó Náraigh, Lennon; Valluri, Prashant; Scott, David; Bethune, Iain; Spelt, Peter

    2013-11-01

    We consider the linear and nonlinear stability of two-phase density-matched but viscosity contrasted fluids subject to laminar Poiseuille flow in a channel, paying particular attention to the formation of three-dimensional waves. The Orr-Sommerfeld-Squire analysis is used along with DNS of the 3D two-phase Navier-Stokes equations using our newly launched TPLS Solver (http://edin.ac/10cRKzS). For the parameter regimes considered, we demonstrate the existence of two distinct mechanisms whereby 3D waves enter the system, and dominate at late time. There exists a direct route, whereby 3D waves are amplified by the standard linear mechanism; for certain parameter classes, such waves grow at a rate less than but comparable to that of most-dangerous two-dimensional mode. Additionally, there is a weakly nonlinear route, whereby a purely spanwise wave couples to a streamwise mode and grows exponentially. We demonstrate these mechanisms in isolation and in concert. Consideration is also given to the ultimate state of these waves: persistent three-dimensional nonlinear waves are stretched and distorted by the base flow, thereby producing regimes of ligaments, ``sheets,'' or ``interfacial turbulence.'' HECToR RAP/dCSE Project e174, HPC-Europa 2.

  2. Low-Shapiro hydrostatic reconstruction technique for blood flow simulation in large arteries with varying geometrical and mechanical properties

    NASA Astrophysics Data System (ADS)

    Ghigo, A. R.; Delestre, O.; Fullana, J.-M.; Lagrée, P.-Y.

    2017-02-01

    The purpose of this work is to construct a simple, efficient and accurate well-balanced numerical scheme for one-dimensional (1D) blood flow in large arteries with varying geometrical and mechanical properties. As the steady states at rest are not relevant for blood flow, we construct two well-balanced hydrostatic reconstruction techniques designed to preserve low-Shapiro number steady states that may occur in large network simulations. The Shapiro number Sh = u / c is the equivalent of the Froude number for shallow water equations and the Mach number for compressible Euler equations. The first is the low-Shapiro hydrostatic reconstruction (HR-LS), which is a simple and efficient method, inspired from the hydrostatic reconstruction technique (HR). The second is the subsonic hydrostatic reconstruction (HR-S), adapted here to blood flow and designed to exactly preserve all subcritical steady states. We systematically compare HR, HR-LS and HR-S in a series of single artery and arterial network numerical tests designed to evaluate their well-balanced and wave-capturing properties. The results indicate that HR is not adapted to compute blood flow in large arteries as it is unable to capture wave reflections and transmissions when large variations of the arteries' geometrical and mechanical properties are considered. On the contrary, HR-S is exactly well-balanced and is the most accurate hydrostatic reconstruction technique. However, HR-LS is able to compute low-Shapiro number steady states as well as wave reflections and transmissions with satisfying accuracy and is simpler and computationally less expensive than HR-S. We therefore recommend using HR-LS for 1D blood flow simulations in large arterial network simulations.

  3. Solitons, Bäcklund transformation and Lax pair for a generalized variable-coefficient Boussinesq system in the two-layered fluid flow

    NASA Astrophysics Data System (ADS)

    Zhao, Xue-Hui; Tian, Bo; Chai, Jun; Wu, Yu-Xiao; Guo, Yong-Jiang

    2016-11-01

    Under investigation in this paper is a generalized variable-coefficient Boussinesq system, which describes the propagation of the shallow water waves in the two-layered fluid flow. Bilinear forms, Bäcklund transformation and Lax pair are derived by virtue of the Bell polynomials. Hirota method is applied to construct the one- and two-soliton solutions. Propagation and interaction of the solitons are illustrated graphically: kink- and bell-shape solitons are obtained; shapes of the solitons are affected by the variable coefficients α1, α3 and α4 during the propagation, kink- and anti-bell-shape solitons are obtained when α3 > 0, anti-kink- and bell-shape solitons are obtained when α3 < 0; Head-on interaction between the two bidirectional solitons, overtaking interaction between the two unidirectional solitons are presented; interactions between the two solitons are elastic.

  4. Identification of geometric parameters influencing the flow-induced vibration of a two-layer self-oscillating computational vocal fold model

    PubMed Central

    Pickup, Brian A.; Thomson, Scott L.

    2011-01-01

    Simplified models have been used to simulate and study the flow-induced vibrations of the human vocal folds. While it is clear that the models’ responses are sensitive to geometry, it is not clear how and to what extent specific geometric features influence model motion. In this study geometric features that played significant roles in governing the motion of a two-layer (body-cover), two-dimensional, finite element vocal fold model were identified. The model was defined using a flow solver based on the viscous, unsteady, Navier–Stokes equations and a solid solver that allowed for large strain and deformation. A screening-type design-of-experiments approach was used to identify the relative importance of 13 geometric parameters. Five output measures were analyzed to assess the magnitude of each geometric parameter’s effect on the model’s motion. The measures related to frequency, glottal width, flow rate, intraglottal angle, and intraglottal phase delay. The most significant geometric parameters were those associated with the cover—primarily the pre-phonatory intraglottal angle—as well as the body inferior angle. Some models exhibited evidence of improved model motion, including mucosal wave-like motion and alternating convergent-divergent glottal profiles, although further improvements are still needed to more closely mimic human vocal fold motion. PMID:21476668

  5. MHD Heat Transfer in Two-Layered Flow of Conducting Fluids through a Channel Bounded by Two Parallel Porous Plates in a Rotating System

    NASA Astrophysics Data System (ADS)

    Linga Raju, T.; Neela Rao, B.

    2016-08-01

    The paper aims to analyze the heat transfer aspects of a two-layered fluid flow in a horizontal channel under the action of an applied magnetic and electric fields, when the whole system is rotated about an axis perpendicular to the flow. The flow is driven by a common constant pressure gradient in the channel bounded by two parallel porous insulating plates, one being stationary and the other one oscillatory. The fluids in the two regions are considered electrically conducting, and are assumed to be incompressible with variable properties, namely, different densities, viscosities, thermal and electrical conductivities. The transport properties of the two fluids are taken to be constant and the bounding plates are maintained at constant and equal temperature. The governing partial differential equations are then reduced to the ordinary linear differential equations by using a two-term series. The temperature distributions in both fluid regions of the channel are derived analytically. The results are presented graphically to discuss the effect on the heat transfer characteristics and their dependence on the governing parameters, i.e., the Hartmann number, Taylor number, porous parameter, and ratios of the viscosities, heights, electrical and thermal conductivities. It is observed that, as the Coriolis forces become stronger, i.e., as the Taylor number increases, the temperature decreases in the two fluid regions. It is also seen that an increase in porous parameter diminishes the temperature distribution in both the regions.

  6. Unsteady two-layered fluid flow of conducting fluids in a channel between parallel porous plates under transverse magnetic field in a rotating system

    NASA Astrophysics Data System (ADS)

    Linga Raju, T.; Neela Rao, B.

    2016-05-01

    An unsteady MHD two-layered fluid flow of electrically conducting fluids in a horizontal channel bounded by two parallel porous plates under the influence of a transversely applied uniform strong magnetic field in a rotating system is analyzed. The flow is driven by a common constant pressure gradient in a channel bounded by two parallel porous plates, one being stationary and the other oscillatory. The two fluids are assumed to be incompressible, electrically conducting with different viscosities and electrical conductivities. The governing partial differential equations are reduced to the linear ordinary differential equations using two-term series. The resulting equations are solved analytically to obtain exact solutions for the velocity distributions (primary and secondary) in the two regions respectively, by assuming their solutions as a combination of both the steady state and time dependent components of the solutions. Numerical values of the velocity distributions are computed for different sets of values of the governing parameters involved in the study and their corresponding profiles are also plotted. The details of the flow characteristics and their dependence on the governing parameters involved, such as the Hartmann number, Taylor number, porous parameter, ratio of the viscosities, electrical conductivities and heights are discussed. Also an observation is made how the velocity distributions vary with the rotating hydromagnetic interaction in the case of steady and unsteady flow motions. The primary velocity distributions in the two regions are seen to decrease with an increase in the Taylor number, but an increase in the Taylor number causes a rise in secondary velocity distributions. It is found that an increase in the porous parameter decreases both the primary and secondary velocity distributions in the two regions.

  7. Passive water flows driven across the isolated rabbit ileum by osmotic, hydrostatic and electrical gradients.

    PubMed Central

    Naftalin, R J; Tripathi, S

    1985-01-01

    Water flows generated by osmotic and hydrostatic pressure and electrical currents were measured in sheets of isolated rabbit ileum at 20 degrees C. Flows across the mucosal and serosal surfaces were monitored continuously by simultaneous measurement of tissue volume change (with an optical lever) and net water flows across one surface of the tissue (with a capacitance transducer). Osmotic gradients were imposed across the mucosal and serosal surfaces of the tissue separately, using probe molecules of various sizes from ethanediol (68 Da) to dextrans (161 000 Da). Flows across each surface were elicited with very short delay. The magnitudes of the flows were proportional to the osmotic gradient and related to the size of the probe molecule. Osmotic flow across the mucosal surface was associated with streaming potentials which were due to electro-osmotic water flow. The mucosal surface is a heteroporous barrier with narrow (0.7 nm radius, Lp (hydraulic conductivity) = (7.6 +/- 1.6) X 10(-9) cm s-1 cmH2O-1) cation-selective channels in parallel with wide neutral pores (ca. 6.5 nm radius, Lp = (2.3 +/- 0.2) X 10(-7) cm s-1 cmH2O-1) which admit large pressure-driven backflows from the submucosa to the lumen. There is additional evidence for a further set of narrow electroneutral pores less than 0.4 nm radius with Lp less than 7 X 10(-9) cm s-1 cmH2O-1. The serosal surface has neutral pores of uniform radius (ca. 6.5 nm), Lp = (7.6 +/- 1.6) X 10(-8) cm s-1 cmH2O-1. Hypertonic serosal solutions (100 mM-sucrose) cause osmotic transfer of fluid from isotonic mucosal solutions into the submucosa, expand it, and elevate the tissue pressure to 19.6 +/- 3.2 cmH2O (n = 4). Conversely, hypertonic mucosal solutions (100 mM-sucrose) draw fluid out of the submucosa in the presence of isotonic serosal solutions, collapse the submucosa, and lower the tissue pressure to -87.7 +/- 4.6 cmH2O (n = 5). Water flows coupled to cation movement could be generated across the mucosal surface in

  8. Drag generation by interfacial waves at an inversion/thermocline in non-hydrostatic flow past an axisymmetric obstacle

    NASA Astrophysics Data System (ADS)

    Teixeira, Miguel A. C.; Paci, Alexandre; Belleudy, Anne

    2017-04-01

    The drag associated with 3D trapped lee waves generated at a density interface by an axisymmetric obstacle is evaluated using a linear non-hydrostatic model. These waves propagate at temperature inversions capping the boundary layer in the atmosphere, or at the oceanic thermocline, generated by, for example, drifting ice keels. They are responsible for near-surface drag that may be misrepresented as turbulent form drag in numerical models. This drag receives contributions from a continuous wavenumber range forced by the obstacle, in contrast with 2D flow (where only discrete wave modes exist), as the waves are able to vary their angle of incidence with respect to the incoming flow to satisfy their dispersion relationship. Hence (and again in contrast with 2D linear flow), the drag is non-zero both for subcritical and supercritical flow, and attains a maximum for a value of the Froude number slightly smaller than 1. This drag maximum has lower magnitude than in the hydrostatic limit, due to the effect of wave dispersion. The drag calculated from the model is in good agreement with that obtained from experiments carried out in a laboratory water flume that use axisymmetric obstacles of different heights, especially for the lowest obstacle (as would be expected). The best agreement is achieved when the effects of both a rigid lid bounding the fluid layer further away from the obstacle, and friction (represented as a Rayleigh damping), are taken into account. The model is not as quantitatively accurate when the highest obstacle used in the experiments is considered, as this corresponds to stronger flow nonlinearity. But, even in that case, the model has a qualitatively correct behaviour, which is much more accurate than the 3D hydrostatic or 2D non-hydrostatic limits. This suggests that 3D and non-hydrostatic effects to a large extent determine the drag behaviour observed in the experiments. The wave signatures associated with this behaviour are dominated by transverse

  9. The use of Tecnomatix software to simulate the manufacturing flows in an industrial enterprise producing hydrostatic components

    NASA Astrophysics Data System (ADS)

    Petrila, S.; Brabie, G.; Chirita, B.

    2016-08-01

    The analysis performed on manufacturing flows within industrial enterprises producing hydrostatic components twos made on a number of factors that influence smooth running of production such: distance between pieces, waiting time from one surgery to another; time achievement of setups on CNC machines; tool changing in case of a large number of operators and manufacturing complexity of large files [2]. To optimize the manufacturing flow it was used the software Tecnomatix. This software represents a complete portfolio of manufacturing solutions digital manufactured by Siemens. It provides innovation by linking all production methods of a product from process design, process simulation, validation and ending the manufacturing process. Among its many capabilities to create a wide range of simulations, the program offers various demonstrations regarding the behavior manufacturing cycles. This program allows the simulation and optimization of production systems and processes in several areas such as: car suppliers, production of industrial equipment; electronics manufacturing, design and production of aerospace and defense parts.

  10. An implicit wetting and drying approach for non-hydrostatic baroclinic flows in high aspect ratio domains

    NASA Astrophysics Data System (ADS)

    Candy, A. S.

    2017-04-01

    A new approach to modelling free surface flows is developed that enables, for the first time, 3D consistent non-hydrostatic baroclinic physics that wets and drys in the large aspect ratio spatial domains that characterise geophysical systems. This is key in the integration of physical models to permit seamless simulation in a single consistent arbitrarily unstructured multiscale and multi-physics dynamical model. A high order continuum representation is achieved through a general Galerkin finite element formulation that guarantees local and global mass conservation, and consistent tracer advection. A flexible spatial discretisation permits conforming domain bounds and a variable spatial resolution, whilst atypical use of fully implicit time integration ensures computational efficiency. Notably this brings the natural inclusion of non-hydrostatic baroclinic physics and a consideration of vertical inertia to flood modelling in the full 3D domain. This has application in improving modelling of inundation processes in geophysical domains, where dynamics proceeds over a large range of horizontal extents relative to vertical resolution, such as in the evolution of a tsunami, or in urban environments containing complex geometric structures at a range of scales.

  11. Speciation of mercury by hydrostatically modified electroosmotic flow capillary electrophoresis coupled with volatile species generation atomic fluorescence spectrometry.

    PubMed

    Yan, Xiu-Ping; Yin, Xue-Bo; Jiang, Dong-Qing; He, Xi-Wen

    2003-04-01

    A novel method for speciation analysis of mercury was developed by on-line hyphenating capillary electrophoresis (CE) with atomic fluorescence spectrometry (AFS). The four mercury species of inorganic mercury Hg(II), methymercury MeHg(I), ethylmercury EtHg(I), and phenylmercury PhHg(I) were separated as mercury-cysteine complexes by CE in a 50-cm x 100-microm-i.d. fused-silica capillary at 15 kV and using a mixture of 100 mmol L(-1) of boric acid and 12% v/v methanol (pH 9.1) as electrolyte. A novel technique, hydrostatically modified electroosmotic flow (HSMEOF) in which the electroosmotic flow (EOF) was modified by applying hydrostatical pressure opposite to the direction of EOF was used to improve resolution. A volatile species generation technique was used to convert the mercury species into their respective volatile species. A newly developed CE-AFS interface was employed to provide an electrical connection for stable electrophoretic separations and to allow on-line volatile species formation. The generated volatile species were on-line detected with AFS. The precisions (RSD, n = 5) were in the range of 1.9-2.5% for migration time, 1.8-6.3% for peak area response, and 2.3-6.1% for peak height response for the four mercury species. The detection limits ranged from 6.8 to 16.5 microg L(-1) (as Hg). The recoveries of the four mercury species in the water samples were in the range of 86.6-111%. The developed technique was successfully applied to speciation analysis of mercury in a certified reference material (DORM-2, dogfish muscle).

  12. Investigation of the two-layer fluid flows with evaporation at interface on the basis of the exact solutions of the 3D problems of convection

    NASA Astrophysics Data System (ADS)

    Goncharova, O. N.; Kabov, O. A.

    2016-10-01

    New physical experiments in the Institute of Thermophysics SB RAS allow one to investigate structure of the flows of liquid layers being under action of the co-current gas flux. The flow topology is determined by four main mechanisms: natural and thermocapillary convection, tangential stresses induced by the flow of gas and mass transfer due to evaporation at the interface. Mathematical modeling of the fluid flows in an infinite channel of the rectangular cross section is carried out on the basis of a solution of special type of the convection equations. The effects of thermodiffusion and diffusive thermal conductivity in the gas phase and evaporation at the thermocapillary interface are taken into consideration. Numerical investigations are performed for the liquid-gas (ethanol-nitrogen) system under normal and low gravity.

  13. Gravity currents in a two-layer stratified ambient: The theory for the steady-state (front condition) and lock-released flows, and experimental confirmations

    NASA Astrophysics Data System (ADS)

    Flynn, M. R.; Ungarish, M.; Tan, A. W.

    2012-02-01

    We consider the propagation of a gravity current of density ρc at the bottom of a two-layer stratified ambient in a horizontal channel of height H, in the high-Reynolds number Boussinesq domain. The study emphasizes theoretical-analytical modeling, however, experimental and Navier-Stokes simulation data are also presented and their comparison with theory is discussed. The stratification parameters are S = (ρ1 - ρ2)/(ρc - ρ2) where ρ is the fluid density, and φ = h1R/H where h1R is the (unperturbed) ambient interface height. Here, 1 and 2 denote, respectively, the lower and upper layer and c denotes the gravity current. The reduced gravity is defined as g' = (ρc/ρ2 - 1)g. Rigorous results are obtained for the steady-state analogue of the classical problem of Benjamin [J. Fluid Mech. 31, 209 (1968)], 10.1017/S0022112068000133, in which the half-infinite gravity current has thickness h and speed U. We thereby demonstrate that the Froude number F= U/(g^' } h)^{1/2} is a function of a = h/H, S, and φ. In general, two solutions (or modes) may be realized. Issues of energy dissipation, sub- vs. supercriticality with respect to long internal waves and, more generally, the influence of upstream-propagating disturbances are discussed. For a gravity current released from a lock of height h0 and length x0, we derive an approximate shallow-water model and show that the motion is in this case governed by Ξ = H/h0, S, and φ. Although the shallow-water model neglects motion in the ambient layers and ignores the impact of propagation on stratification, the gravity current front speed in the slumping stage is in excellent agreement with measured data. Our theoretical solutions are consistent with previous results (in particular, Holyer and Huppert [J. Fluid Mech. 100, 739 (1980)] and Tan et al. [Environ. Fluid Mech. 11, 203 (2011)]), but have the advantages of being (i) derived without reliance on adjustable constants and ad hoc closures; (ii) applicable to a

  14. A Hamiltonian Particle-Mesh Method for Hydrostatic Flow in Isentropic Coordinates

    NASA Astrophysics Data System (ADS)

    Peeters, Bob; Bokhove, Onne; Frank, Jason

    2010-05-01

    Although our climate is ultimately driven by (nonuniform) solar heating, many aspects of the flow can be understood qualitatively from forcing-free and frictionless dynamics. In the limit of zero forcing and dissipation, our weather system falls under the realm of Hamiltonian fluid dynamics and the flow conserves potential vorticity (PV), energy and phase-space structure. We think that discrete conservation of phase-space structure is essential for reproducing the correct statistics in climate forecasts. To find a Hamiltonian discretization, we start from the Lagrangian momentum equations with entropy as vertical label coordinate. Entropy is conserved on fluid parcels in adiabatic flow. New is that we view the potential as an Eulerian function. It means that the Lagrangian equation for mass conservation is replaced by an integral relation over all fluid parcels, recovering the Eulerian density field. This is the so-called parcel formulation [1]. The spatial discretization consists of two steps: 1) a finite element (FEM) discretization in the entropic direction, and 2) a discretization of horizontal Lagrangian label space. It leads to a discrete Poisson bracket constituting a Hamiltonian set of ODE's for a collection of discrete fluid particles moving on isentropic surfaces. The resulting Hamiltonian Particle-Mesh method, akin to [3], conserves mass, PV, energy and phase-space structure. A symplectic time integrator is used for our Hamiltonian system. The resulting fully discrete system allows backward error analysis for the energy. It is conserved without any drift in energy. We will prove the energy conservation, and show a systematic derivation of the Eulerian FEM Poisson bracket, following [2]. REFERENCES [1] O. Bokhove and M. Oliver, Parcel Eulerian-Lagrangian fluid dynamics for rotating geophysical flows, Proc. Roy. Soc. A. 462, pp. 2563-2573 (2006) [2] O. Bokhove and M. Oliver, Hamiltonian N layer model for atmospheric dynamics, Geophys. Astrophys. Fluid Dyn

  15. Investigations of Reduced Equations for Rotating, Stratified and Non-hydrostatic Flows

    NASA Astrophysics Data System (ADS)

    Nieves, David J.

    This thesis is a collection of studies concerning an asymptotically reduced equation set derived from the Boussinesq approximation describing rotationally constrained geophysical flow. The first investigation is concerned with a statistical identification of coherent and long-lived structures in rotationally constrained Rayleigh-Benard convection. Presently, physical laboratory limitations challenge experimentalists while spatio-temporal resolution requirements challenges numericists performing direct numerical simulations of the Boussinesq equations. These challenges prevent an exhaustive analysis of the flow morphology in the rapid rotating limit. In this study the flow morphologies obtained from simulations of the reduced equations are investigated from a statistical perspective. Auto- and cross-correlations are computed from temporal and spatial signals that synthesize experimental data that may be obtained in laboratory experiments via thermistor measurements or particle image velocimetry. The statistics used can be employed in laboratory experiments to identify regime transitions in flow morphology, capture radial profiles of coherent structures, and extract transport properties belonging to these structures. These results provide a foundation for comparison and a measure for understanding the extent to which rotationally constrained regime has been accessed by laboratory experiments and direct numerical simulations. A related study comparing the influence of fixed temperature and fixed heat flux thermal boundary conditions on rapidly rotating convection in the plane layer geometry is also investigated and briefly summarized for the case of stress-free mechanical boundary conditions. It is shown that the difference between these thermal boundary conditions on the interior geostrophically balanced convection is asymptotically weak. Through a simple rescaling of thermal variables, the leading order reduced system is shown to be equivalent for both thermal

  16. Two-layer Tripole Model

    NASA Astrophysics Data System (ADS)

    Sokolovskiy, M. A.; Verron, J.; Yakovenko, O. I.

    Three-vortex filament problem for the case of both zero average circulation and im- pulse in a 2D two-layer incompressible fluid is investigated. In this framework, a model of tripolar structures is constructed with one vortex located in the upper layer and two vortices situated in the lower layer. Two special cases of the intensity dis- tribution were studied: (-2; 1, 1) ­ a strong central vortex is over two week vortices placed in the lower layer; (-1; 2, -1) ­ a strong central vortex is in the lower layer, and the week vortices are located one in the upper, and the second in the lower layers. The results give two types of stationary axially symmetrical configurations in the first case: a) an ordinary roundabout ­ two lower-layer vortices are rotating in the direction in- duced by the central vortex; b) an inversed roundabout ­ the lower-layer vortices are rotating in the direction opposite to the central upper layer vortex because of the in- tralayer interaction prevalence. In the second case, all three vortices form a colinear configuration and always rotate around the common vorticity center in the direction implied by the stronger vortex. Such configuration received the name of eccentric roundabout. Comparison of calcu- lation results for discrete and finite-core vortices is made. Support of RFBR (Grant 01-05-64646) is gratefully acknowledged.

  17. Associative Flow Rule Used to Include Hydrostatic Stress Effects in Analysis of Strain-Rate-Dependent Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2004-01-01

    designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. The nonlinearity and the strain-rate dependence of the composite response are due primarily to the matrix constituent. Therefore, in developing material models to be used in the design of impact-resistant composite engine cases, the deformation of the polymer matrix must be correctly analyzed. However, unlike in metals, the nonlinear response of polymers depends on the hydrostatic stresses, which must be accounted for within an analytical model. By applying micromechanics techniques along with given fiber properties, one can also determine the effects of the hydrostatic stresses in the polymer on the overall composite deformation response. First efforts to account for the hydrostatic stress effects in the composite deformation applied purely empirical methods that relied on composite-level data. In later efforts, to allow polymer properties to be characterized solely on the basis of polymer data, researchers at the NASA Glenn Research Center developed equations to model the polymers that were based on a non-associative flow rule, and efforts to use these equations to simulate the deformation of representative polymer materials were reasonably successful. However, these equations were found to have difficulty in correctly analyzing the multiaxial stress states found in the polymer matrix constituent of a composite material. To correct these difficulties, and to allow for the accurate simulation of the nonlinear strain-rate-dependent deformation analysis of polymer matrix composites, in the efforts reported here Glenn researchers reformulated the polymer constitutive equations from basic principles using the concept of an associative flow rule. These revised equations were characterized and validated in an

  18. Modeling Tsunami Wave Generation Using a Two-layer Granular Landslide Model

    NASA Astrophysics Data System (ADS)

    Ma, G.; Kirby, J. T., Jr.; Shi, F.; Grilli, S. T.; Hsu, T. J.

    2016-12-01

    Tsunamis can be generated by subaerial or submarine landslides in reservoirs, lakes, fjords, bays and oceans. Compared to seismogenic tsunamis, landslide or submarine mass failure (SMF) tsunamis are normally characterized by relatively shorter wave lengths and stronger wave dispersion, and potentially may generate large wave amplitudes locally and high run-up along adjacent coastlines. Due to a complex interplay between the landslide and tsunami waves, accurate simulation of landslide motion as well as tsunami generation is a challenging task. We develop and test a new two-layer model for granular landslide motion and tsunami wave generation. The landslide is described as a saturated granular flow, accounting for intergranular stresses governed by Coulomb friction. Tsunami wave generation is simulated by the three-dimensional non-hydrostatic wave model NHWAVE, which is capable of capturing wave dispersion efficiently using a small number of discretized vertical levels. Depth-averaged governing equations for the granular landslide are derived in a slope-oriented coordinate system, taking into account the dynamic interaction between the lower-layer granular landslide and upper-layer water motion. The model is tested against laboratory experiments on impulsive wave generation by subaerial granular landslides. Model results illustrate a complex interplay between the granular landslide and tsunami waves, and they reasonably predict not only the tsunami wave generation but also the granular landslide motion from initiation to deposition.

  19. Two-layer tubes from cubic crystals

    NASA Astrophysics Data System (ADS)

    Goldstein, R. V.; Gorodtsov, V. A.; Lisovenko, D. S.; Volkov, M. A.

    2016-12-01

    Effective Young's moduli and Poisson's ratios of two-layer tubes from cubic crystals have been analyzed theoretically. It is shown (using derived formulas for numerical estimates) that the mechanical properties of two-layer tube composites from auxetics and nonauxetics are not described by the mixture rule. It is demonstrated that the deviation of the effective modulus from the mixture rule predictions rapidly increases with an increase in Young's modulus of the nonauxetic components of a composite. It is established that, combining auxetics and nonauxetics in layered tubes, one can obtain, depending on the packing order in layers, either a strong increase or a decrease in auxeticity.

  20. The lifetimes of Pharaonis phoborhodopsin signaling states depend on the rates of proton transfers--effects of hydrostatic pressure and stopped flow experiments.

    PubMed

    Kikukawa, Takashi; Saha, Chabita K; Balashov, Sergei P; Imasheva, Eleonora S; Zaslavsky, Dmitry; Gennis, Robert B; Abe, Takayuki; Kamo, Naoki

    2008-01-01

    Pharaonis phoborhodopsin (ppR), a negative phototaxis receptor of Natronomonas pharaonis, undergoes photocycle similar to the light-driven proton pump bacteriorhodopsin (BR), but the turnover rate is much slower due to much longer lifetimes of the M and O intermediates. The M decay was shown to become as fast as it is in BR in the L40T/F86D mutant. We examined the effects of hydrostatic pressure on the decay of these intermediates. For BR, pressure decelerated M decay but slightly affected O decay. In contrast, with ppR and with its L40T/F86D mutant, pressure slightly affected M decay but accelerated O decay. Clearly, the pressure-dependent factors for M and O decay are different in BR and ppR. In order to examine the deprotonation of Asp75 in unphotolyzed ppR we performed stopped flow experiments. The pH jump-induced deprotonation of Asp75 occurred with 60 ms, which is at least 20 times slower than deprotonation of the equivalent Asp85 in BR and about 10-fold faster than the O decay of ppR. These data suggest that proton transfer is slowed not only in the cytoplasmic channel but also in the extracellular channel of ppR and that the light-induced structural changes in the O intermediate of ppR additionally decrease this rate.

  1. High pressure stopped-flow apparatus for the rapid mixing and subsequent study of two fluids under high hydrostatic pressures

    NASA Astrophysics Data System (ADS)

    Karan, Daniel M.; Macey, Robert I.

    1980-08-01

    A stopped-flow apparatus is described for the rapid mixing and subsequent study of two dissimilar fluids under pressures up to 1200 bar. The device consists of two identical pressure chambers which contain the two fluids, a third pressure chamber which contains gas to maintain the pressure in the system, an optical port for photometric observation, and various connections. The device has been used to measure reaction times on the order of a hundred milliseconds to tens of seconds, using a maximum of 2 ml of each reagent per experimental determination. The dead time is found to be 5-25 ms with minium average flow velocities of 2.0 m/s. The construction and operation of the device are described and examples of water transport data in red blood cells and the bromophenolblue indicated chemical reaction of NaHCO3 and HCl under pressure are presented.

  2. A two-layered suspension (particle-fluid) model for non-Newtonian fluid flow in a catheterized arterial stenosis with slip condition at the wall of stenosed artery

    NASA Astrophysics Data System (ADS)

    Ponalagusamy, R.

    2017-05-01

    The primary concern of the present investigation is to study blood flow in a porous catheterized artery with an axially asymmetric and radially symmetric stenosis (constriction). In the present study, blood is characterized as a two-fluid system containing a cell-rich zone of suspension of blood cells described to be a particle-fluid suspension (Jeffrey fluid) and a cell-free plasma (Newtonian fluid) layer near the wall. The systematic expressions for flow characteristics such as fluid phase and particle phase velocities, flow rate, wall shear stress, resistive force, and frictional forces on walls of arterial stenosis and catheter are derived. It is recorded that the wall shear stress, flow resistance, and frictional forces are found to be increased with catheter size, red cell concentration, and slip parameter. When blood obeys the law of constitutive equation of a Jeffrey fluid, the flowing blood experiences lesser wall shear stress, flow resistance and frictional forces as compared to the case of blood being categorized as a Newtonian fluid. The increase in Darcy number, blood rheology as Jeffrey fluid, and the presence of peripheral plasma layer near the wall serves to reduce substantially the values of the flow characteristics (wall shear stress, flow resistance and frictional forces).

  3. Nonlinear ring waves in a two-layer fluid

    NASA Astrophysics Data System (ADS)

    Khusnutdinova, Karima R.; Zhang, Xizheng

    2016-10-01

    Surface and interfacial weakly-nonlinear ring waves in a two-layer fluid are modelled numerically, within the framework of the recently derived 2 + 1-dimensional cKdV-type equation. In a case study, we consider concentric waves from a localised initial condition and waves in a 2D version of the dam-break problem, as well as discussing the effect of a piecewise-constant shear flow. The modelling shows, in particular, the formation of 2D dispersive shock waves and oscillatory wave trains.

  4. Hydrostatic Adjustment in Vertically Stratified Atmospheres

    NASA Technical Reports Server (NTRS)

    Duffy, Dean G.

    2000-01-01

    Hydrostatic adjustment due to diabatic heat in two nonisothermal atmospheres is examined. In the first case the temperature stratification is continuous; in the second case the atmosphere is composed of a warm, isothermal troposphere and a colder, isothermal semi-infinitely deep stratosphere.In both cases hydrostatic adjustment, to a good approximation, follows the pattern found in the Lamb problem (semi-infinitely deep. isothermal atmosphere): Initially we have acoustic waves with the kinetic energy increasing or decreasing at the expense of available elastic energy. After this initial period the acoustic waves evolve into acoustic-gravity waves with the kinetic, available potential and available elastic energies interacting with each other. Relaxation to hydrostatic balance occurs within a few oscillations. Stratification in an atmosphere with a continuous temperature profile affects primarily the shape and amplitude of the disturbances. In the two-layer atmosphere, a certain amount of energy is trapped in the tropospheric waveguide as disturbances reflect off the tropopause and back into the troposphere. With each internal reflection a portion of this trapped energy escapes and radiates to infinity.

  5. Vorticity Transport in a Two Layer, Double Gyre Ocean Basin

    NASA Astrophysics Data System (ADS)

    Kaiser, Bryan; Clayson, Carol Anne; Jayne, Steve

    2016-11-01

    The double gyre ocean circulations predicted by strongly frictional, barotropic, linearized ocean models qualitatively agree with the patterns of large scale gyres in the world ocean. However, nonlinear ocean models featuring less intense eddy diffusion parameterization can converge to an infinite number of statistically stationary circulations, depending on the parameterization of dissipation of energy and vorticity. Patterns of vorticity flux and dissipation in a barotropic ocean have been examined previous studies; in this work the inclusion of the first baroclinic mode is examined. The first vertical mode permits the model to be split into two layers, the top approximating the thermocline and the bottom approximating the abyssal circulation. The separation into two layers not only adds realism and but also removes the nonphysical direct restraint of the upper ocean by bottom friction. Steady state circulations for various boundary conditions, sources and sinks of vorticity, and Reynolds numbers are simulated using a parallel pseudo-spectral quasi-geostrophic flow solver and mechanisms of vorticity flux and dissipation are discussed.

  6. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  7. A Hydrostatic Paradox Revisited

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2012-01-01

    This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon…

  8. The Hydrostatic Paradox.

    ERIC Educational Resources Information Center

    Wilson, Alpha E.

    1995-01-01

    Presents an example demonstrating the quantitative resolution of the hydrostatic paradox which is the realization that the force due to fluid pressure on the bottom of a vessel can be considerably greater or considerably less than the weight of the fluid in the vessel. (JRH)

  9. A New Two-Layer Photoresist.

    NASA Astrophysics Data System (ADS)

    Miura, Konoe; Ochiai, Tameichi; Kameyama, Yasuhiro; Uoya, Shigeo; Yamazaki, Teruhiko

    1986-07-01

    A new positive working photoresist which is applicable to the two-layer resist techniq using a current g-line stepper has been developed. This resist consists of a naphth, quinone diazide photoactive compound and a silicon containing novolak resin, which synthesized from m-trimethylsilylphenol, m-cresol, and formaldehyde by condensation r action according to the standard method. The 02 RIE durability of this resist gets great with increase of molar fraction of the silylphenol in the binder. The resist comprising resin prepared from the silylphenol alone by condensation with formaldehyde shows the highest 02 RIE durability,although resolution, sensitivity, and coating property are n sufficient. These properties are improved by incorporation of m-cresol moiety into t binder resin. Novo 1 ak prepared from a mixture of 30 mole % of m- creso 1 and 70 mole % of t silylphenol gives sufficient resolution, reasonable sensitivity and good coating proper leaving RIE durability at fairly high level. The molecular weight and the content of t sensitizer were optimized. The resist is completely compatible with current resist processings. The sensitivity good enough for the usual application and essentially no unexposed-film thickness loss w observed when it is developed with 2.38% tetramethylammonium hydroxide solution. Gam] value is fairly large and line and space as small as 0.6um can be resolved with go, profiles when it is exposed using a g-line stepper equipped with a lens of N.A.=0.35. This resist can be applied to the two-level resist process. MP-1400 was used as planarization layer and after curing at 200 C the present resist was applied on that as thin imaging resist. After exposure and development of the top layer, the pattern of 0. line and space was transferred to the bottom resist by 02 RIE with nearly vertical sil walls. The etch rates of top and bottom resist are shown to be 450 and 1360A/min, respectively.

  10. Hydrostatic Modeling of Buoyant Plumes

    NASA Astrophysics Data System (ADS)

    Stroman, A.; Dewar, W. K.; Wienders, N.; Deremble, B.

    2014-12-01

    The Deepwater Horizon oil spill in the Gulf of Mexico has led to increased interest in understanding point source convection dynamics. Most of the existing oil plume models use a Lagrangian based approach, which computes integral measures such as plume centerline trajectory and plume radius. However, this approach doesn't account for feedbacks of the buoyant plume on the ambient environment. Instead, we employ an Eulerian based approach to acquire a better understanding of the dynamics of buoyant plumes. We have performed a series of hydrostatic modeling simulations using the MITgcm. Our results show that there is a dynamical response caused by the presence of the buoyant plume, in that there is a modification of the background flow. We find that the buoyant plume becomes baroclinically unstable and sheds eddies at the neutral buoyancy layer. We also explore different scenarios to determine the effect of the buoyancy source and the temperature stratification on the evolution of buoyant plumes.

  11. Two-Layer Models for Landslide-Generated Tsunamis

    NASA Astrophysics Data System (ADS)

    Kirby, J. T., Jr.; Nicolsky, D.; Ma, G.; Shi, F.; Hsu, T. J.; Schnyder, J. S. D.

    2014-12-01

    We describe the development of a model for landslide tsunami generation based on a depth-integrated, fully deformable lower layer, and apply the resulting model to several laboratory and field cases. The approach follows on earlier studies where models for the slide layer and overlying water layer are formulated in the depth integrated, shallow water approximation, with kinematic and pressure coupling between the layers. In the present study, we use the 3D nonhydrostatic model of Ma et al (2012) to retain fully dispersive behavior in the upper fluid layer. In perfect fluid applications for shallow or intermediate depth waves, the model has been shown to predict tsunami response to solid slides (Enet and Grilli, 2007) with good accuracy using only three vertical sigma levels, making it computationally competitive with weakly dispersive Boussinesq formulations using a single depth-integrated layer. The effect of non-hydrostatic acceleration effects in the lower, depth integrated layer (resulting from steep substrate slopes) is implemented using the approach of Yamazaki et al (2009), who used a layer-averaged approximation for vertical acceleration to correct the hydrostatic pressure distribution. The two coupled models are formulated using a finite volume, TVD approach. Lateral boundaries of the slide volume may be arbitrarily approached relative to the initial still water shoreline, and thus the triggering event may be either submarine, subaerial, or a combination of the two. In our first implementation, we assume the lower layer to be a simple, viscous Newtonian fluid, following the approach of Jiang and LeBlond (1994) as corrected by Fine et al (1998). An alternate model is also constructed based on a rheology model representing a granular or debris flow supported by intergranular stresses, following Savage and Hutter (1989) and Iverson (1997). Both models amount to the addition of a single mass and horizontal momentum equation to the three-layer perfect fluid

  12. Implementation of an Associative Flow Rule Including Hydrostatic Stress Effects Into the High Strain Rate Deformation Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

    2003-01-01

    A previously developed analytical formulation has been modified in order to more accurately account for the effects of hydrostatic stresses on the nonlinear, strain rate dependent deformation of polymer matrix composites. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical J2 plasticity theory definitions of effective stress and effective inelastic strain, along with the equations used to compute the components of the inelastic strain rate tensor, are appropriately modified. To verify the revised formulation, the shear and tensile deformation of two representative polymers are computed across a wide range of strain rates. Results computed using the developed constitutive equations correlate well with experimental data. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite for several fiber orientation angles across a variety of strain rates. The computed values compare well to experimentally obtained results.

  13. Interfacial Stability in a Two-Layer Benard Problem.

    DTIC Science & Technology

    1985-04-01

    STABILITY IN A TWO-LAYER BENARD PROBLEM Yuriko Renardy Technical Summary Report #2814 April 1985 I cti- Work Unit Number 2 - Physical Mathematics...34•"• -••’-’• ^ ••’••• VI , •• W -•- • •- ’•"• INTERFACIAL STABILITY IN A TWO-LAYER BENARD PROBLEM Yuriko Renardy I. INTRODUCTION Two layers of fluids are...Subtltl») INTERFACIAL STABILITY IN A TWO-LAYER BENARD PROBLEM 7. AUTMORf.; Yuriko Renardy »• PERFORMING ORGANIZATION NAME AND ADDRESS

  14. A Two-layer Model for the Simulation of the VARTM Process with Resin Distribution Layer

    NASA Astrophysics Data System (ADS)

    Young, Wen-Bin

    2013-12-01

    Vacuum assisted resin transfer molding (VARTM) is one of the important processes to fabricate high performance composites. In this process, resin is drawn into the mold to impregnate the fiber reinforcement to a form composite. A resin distribution layer with high permeability was often introduced on top of the fiber reinforcement to accelerate the filling speed. Due to the difference of the flow resistance in the resin distribution layer and the reinforcement as well as the resulting through thickness transverse flow, the filling flow field is intrinsically three-dimensional. This study developed a two-layer model with two-dimensional formulation to simulate the filling flow of the VARTM process with a resin distribution layer. Two-dimensional flow was considered in each layer and a transverse flow in the thickness direction was estimated between the two layers. Thermal analysis including the transverse convection was also performed to better simulate the temperature distribution.

  15. Hydrostatic lubrication in turbopumps of rocket engines

    NASA Astrophysics Data System (ADS)

    Bassani, R.; Ciulli, E.; Piccigallo, B.; Staffilano, U.

    2003-09-01

    The paper presents a computational procedure that can be useful in assessing the main performance parameters (load, flow rate, attitude angle) of hydrostatic journal bearings, without resorting to full numerical computing. The procedure is based on the "lumped resistance method", which has been extended to take into account turbulence and inertia effects. Comparison with available experimental data shows a pretty reasonable agreement, in spite of the heavy approximations that have been introduced.

  16. Application of two-layer methods for the evaluation of wind effects on a cubic building

    SciTech Connect

    Zhou, Y.; Stathopoulos, T.

    1996-11-01

    The two-layer methods combining the {kappa}-{var_epsilon} model in the external, fully turbulent flow region with either the one-equation model or the low-Reynolds-number modified {kappa}-{var_epsilon} model in the near-wall area have been tested in computing the wind conditions around a cubic building. Results were compared with those form the {kappa}-{var_epsilon} model computation as well as those form the experiments. Comparison shows that neither the {kappa}-{var_epsilon} model approach nor the modified {kappa}-{var_epsilon} model-based two-layer method can represent the flow separation above the roof surface and near the side walls. The one-equation model based on the two-layer approach, however, is effective in predicting the separation. The numerical prediction of the wind-induced pressure on building surfaces, especially on the roof and side walls, is also improved as compared with the other two methods.

  17. Characterizing the Severe Turbulence Environments Associated with Commercial Aviation Accidents. Part 2; Hydrostatic Mesobeta Scale Numerical Simulations of Supergradient Wind Flow and Streamwise Ageostrophic Frontogenesis

    NASA Technical Reports Server (NTRS)

    Kaplan, Michael L.; Huffman, Allan W.; Lux, Kevin M.; Cetola, Jeffrey D.; Charney, Joseph J.; Riordan, Allen J.; Lin, Yuh-Lang; Waight, Kenneth T., III; Proctor, Fred (Technical Monitor)

    2003-01-01

    Simulation experiments reveal key processes that organize a hydrostatic environment conducive to severe turbulence. The paradigm requires juxtaposition of the entrance region of a curved jet stream, which is highly subgeostrophic, with the entrance region of a straight jet stream, which is highly supergeostrophic. The wind and mass fields become misphased as the entrance regions converge resulting in the significant spatial variation of inertial forcing, centripetal forcing, and along- and cross-stream pressure gradient forcing over a mesobeta scale region. This results in frontogenesis and the along-stream divergence of cyclonic and convergence of cyclonic ageostrophic vertical vorticity. The centripetally forced mesoscale front becomes the locus of large gradients of ageostrophic vertical vorticity along an overturning isentrope. This region becomes favorable for streamwise vorticity gradient formation enhancing the environment for organization of horizontal vortex tubes in the presence of buoyant forcing.

  18. On two-layer models and the similarity functions for the PBL

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1982-01-01

    An operational Planetary Boundary Layer model which employs similarity principles and two-layer patching to provide state-of-the-art parameterization for the PBL flow is used to study the popularly used similarity functions, A and B. The expected trends with stratification are shown. The effects of baroclinicity, secondary flow, humidity, latitude, surface roughness variation and choice of characteristic height scale are discussed.

  19. On measuring similarity between different two-layered networks

    NASA Astrophysics Data System (ADS)

    Blatt, Marcelo G.

    1996-04-01

    In this paper we present a method for calculating 0305-4470/29/8/007/img1, the generalization error of two-layered networks. 0305-4470/29/8/007/img1 is the fraction of the input space for which two networks yield different answers, therefore it is a good index to measure the similarity between them. The method presented here is an extension of work reported previously. It is applied here to the case of a single-layer perceptron (which can be regarded as a particular two-layered perceptron) that tries to imitate a two-layered network. The particular realizations of such a two-layered network that are analysed here are the `parity machine', the `and machine' and the `committee machine'. We have also compared the input - output mapping of a committee and a parity machine.

  20. Two-layer anti-reflection strategies for implant applications

    NASA Astrophysics Data System (ADS)

    Guerrero, Douglas J.; Smith, Tamara; Kato, Masakazu; Kimura, Shigeo; Enomoto, Tomoyuki

    2006-03-01

    A two-layer bottom anti-reflective coating (BARC) concept in which a layer that develops slowly is coated on top of a bottom layer that develops more rapidly was demonstrated. Development rate control was achieved by selection of crosslinker amount and BARC curing conditions. A single-layer BARC was compared with the two-layer BARC concept. The single-layer BARC does not clear out of 200-nm deep vias. When the slower developing single-layer BARC was coated on top of the faster developing layer, the vias were cleared. Lithographic evaluation of the two-layer BARC concept shows the same resolution advantages as the single-layer system. Planarization properties of a two-layer BARC system are better than for a single-layer system, when comparing the same total nominal thicknesses.

  1. Experimentally excellent beaming in a two-layer dielectric structure

    DOE PAGES

    Tasolamprou, Anna C.; Zhang, Lei; Kafesaki, Maria; ...

    2014-09-15

    We demonstrate both experimentally and theoretically that a two-layer dielectric structure can provide collimation and enhanced transmission of a Gaussian beam passing through it. This is due to formation of surface localized states along the layered structure and the coupling of these states to outgoing propagating waves. As a result, a system of multiple cascading two-layers can sustain the beaming for large propagation distances.

  2. Experimentally excellent beaming in a two-layer dielectric structure

    SciTech Connect

    Tasolamprou, Anna C.; Zhang, Lei; Kafesaki, Maria; Koschny, Thomas; Soukoulis, Costas M.

    2014-09-15

    We demonstrate both experimentally and theoretically that a two-layer dielectric structure can provide collimation and enhanced transmission of a Gaussian beam passing through it. This is due to formation of surface localized states along the layered structure and the coupling of these states to outgoing propagating waves. As a result, a system of multiple cascading two-layers can sustain the beaming for large propagation distances.

  3. Infinite Phased Array of Microstrip Dipoles in Two Layers

    DTIC Science & Technology

    1989-01-01

    Green’s function appropriate to the two-layer substrate- superstrate structure was used in the formulation of the method of moMents - (continued on back) 20...analysis is presented for an infinite phased array of microstrip dipoles embedded within a two layer substrate structure (sub- strate- superstrate ...characterization of input impedance as a function of phase scan angle. Results for several sub- strate- superstrate structures illustrate the utility of the single

  4. Non-hydrosatatic Effects in Exchange Flows

    NASA Astrophysics Data System (ADS)

    Kanarska, Y.

    2003-12-01

    An important class of stratified flows is exchange flows in which fluids of different densities move in opposite directions through a channel. These flows are studied mainly in the frame of an internal hydraulic theory. However geophysical flows are more complicated than a two-layer hydraulic solution. In this paper the hydrodynamics of exchange flows is investigated with focusing on the role of non-hydrostatic effects, friction, mixing and an impact of an unsteady barotropic tide forcing on hydrodynamics of water exchange in the straits. Special attention is given to design of physically relevant time-dependence boundary conditions at the open boundaries. The numerical tool for investigations is a three-dimensional, non-hydrostatic, numerical model of free surface stratified flows (Kanarska Y., Maderich V, 2003). The model is a non-hydrostatic extension of the free-surface primitive equation POM model. A mode splitting technique, decomposition of pressure and velocity fields into hydrostatic and non-hydrostatic components and sequential calculation of these components are the base of numerical algorithm of the model. At first the model is used to investigate different regimes of exchange flows ranging from dispersive gravity waves in the seiche flows to shear instability in the lock-exchange flows including transition regimes where both mechanisms occur. The investigation of the energetics and the resulting diapycnal mixing is carried on the base of the analysis of available potential energy. Then the model is applied for an investigation of the exchange flows in a long and narrow strait with a sill or contraction for the configuration of experiments of Maderich (2000) and to the simulation of the water circulation in the Dadanelles strait. Calculations and analysis based on a three-layer decomposition with an intermediate layer of variable density showed the importance of entrainment and friction in the long straits. As a result the composite Froude number is

  5. Nonlinear Hydrostatic Adjustment.

    NASA Astrophysics Data System (ADS)

    Bannon, Peter R.

    1996-12-01

    The final equilibrium state of Lamb's hydrostatic adjustment problem is found for finite amplitude heating. Lamb's problem consists of the response of a compressible atmosphere to an instantaneous, horizontally homogeneous heating. Results are presented for both isothermal and nonisothermal atmospheres.As in the linear problem, the fluid displacements are confined to the heated layer and to the region aloft with no displacement of the fluid below the heating. The region above the heating is displaced uniformly upward for heating and downward for cooling. The amplitudes of the displacements are larger for cooling than for warming.Examination of the energetics reveals that the fraction of the heat deposited into the acoustic modes increases linearly with the amplitude of the heating. This fraction is typically small (e.g., 0.06% for a uniform warming of 1 K) and is essentially independent of the lapse rate of the base-state atmosphere. In contrast a fixed fraction of the available energy generated by the heating goes into the acoustic modes. This fraction (e.g., 12% for a standard tropospheric lapse rate) agrees with the linear result and increases with increasing stability of the base-state atmosphere.The compressible results are compared to solutions using various forms of the soundproof equations. None of the soundproof equations predict the finite amplitude solutions accurately. However, in the small amplitude limit, only the equations for deep convection advanced by Dutton and Fichtl predict the thermodynamic state variables accurately for a nonisothermal base-state atmosphere.

  6. Improved efficient routing strategy on two-layer complex networks

    NASA Astrophysics Data System (ADS)

    Ma, Jinlong; Han, Weizhan; Guo, Qing; Zhang, Shuai; Wang, Junfang; Wang, Zhihao

    2016-10-01

    The traffic dynamics of multi-layer networks has become a hot research topic since many networks are comprised of two or more layers of subnetworks. Due to its low traffic capacity, the traditional shortest path routing (SPR) protocol is susceptible to congestion on two-layer complex networks. In this paper, we propose an efficient routing strategy named improved global awareness routing (IGAR) strategy which is based on the betweenness centrality of nodes in the two layers. With the proposed strategy, the routing paths can bypass hub nodes of both layers to enhance the transport efficiency. Simulation results show that the IGAR strategy can bring much better traffic capacity than the SPR and the global awareness routing (GAR) strategies. Because of the significantly improved traffic performance, this study is helpful to alleviate congestion of the two-layer complex networks.

  7. Three-D CFD analysis of hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Lin, Shyi-Jang; Hibbs, Robert I., Jr.

    1993-07-01

    The hydrostatic bearing promises life and speed characteristics currently unachievable with rolling element bearings alone. In order to achieve the speed and life requirements of the next generation of rocket engines, turbopump manufacturers are proposing hydrostatic bearings to be used in place of, or in series with, rolling element bearings. The design of a hydrostatic bearing is dependent on accurate pressure in the bearing. The stiffness and damping of the hydrostatic bearing is very sensitive to the bearing recess pressure ratio. In the conventional approach, usually ad hoc assumptions were made in determining the bearing pressure of this approach is inherently incorrect. In the present paper, a more elaborate approach to obtain bearing pressure is used. The bearing pressure and complete flow features of the bearing are directly computed by solving the complete 3-D Navier Stokes equation. The code used in the present calculation is a modified version of REACT3D code. Several calculations have been performed for the hydrostatic bearing designed and tested at Texas A&M. Good agreement has been obtained between computed and test results. Detailed flow features in the bearing will also be described and discussed.

  8. Three-D CFD Analysis of Hydrostatic Bearings

    NASA Technical Reports Server (NTRS)

    Lin, Shyi-Jang; Hibbs, Robert I., Jr.

    1993-01-01

    The hydrostatic bearing promises life and speed characteristics currently unachievable with rolling element bearings alone. In order to achieve the speed and life requirements of the next generation of rocket engines, turbopump manufacturers are proposing hydrostatic bearings to be used in place of, or in series with, rolling element bearings. The design of a hydrostatic bearing is dependent on accurate pressure in the bearing. The stiffness and damping of the hydrostatic bearing is very sensitive to the bearing recess pressure ratio. In the conventional approach, usually ad hoc assumptions were made in determining the bearing pressure of this approach is inherently incorrect. In the present paper, a more elaborate approach to obtain bearing pressure is used. The bearing pressure and complete flow features of the bearing are directly computed by solving the complete 3-D Navier Stokes equation. The code used in the present calculation is a modified version of REACT3D code. Several calculations have been performed for the hydrostatic bearing designed and tested at Texas A&M. Good agreement has been obtained between computed and test results. Detailed flow features in the bearing will also be described and discussed.

  9. NASA. Marshall Space Flight Center Hydrostatic Bearing Activities

    NASA Technical Reports Server (NTRS)

    Benjamin, Theodore G.

    1991-01-01

    The basic approach for analyzing hydrostatic bearing flows at the Marshall Space Flight Center (MSFC) is briefly discussed. The Hydrostatic Bearing Team has responsibility for assessing and evaluating flow codes; evaluating friction, ignition, and galling effects; evaluating wear; and performing tests. The Office of Aerospace and Exploration Technology Turbomachinery Seals Tasks consist of tests and analysis. The MSFC in-house analyses utilize one-dimensional bulk-flow codes. Computational fluid dynamics (CFD) analysis is used to enhance understanding of bearing flow physics or to perform parametric analysis that are outside the bulk flow database. As long as the bulk flow codes are accurate enough for most needs, they will be utilized accordingly and will be supported by CFD analysis on an as-needed basis.

  10. Two-layer sheet of gelatin: A new topical hemostatic agent.

    PubMed

    Takagi, Toshitaka; Tsujimoto, Hiroyuki; Torii, Hiroko; Ozamoto, Yuki; Hagiwara, Akeo

    2016-11-02

    Uncontrolled surgical bleeding is associated with increased morbidity, mortality, and hospital cost. Topical hemostatic agents available today have problems controlling hemostatic effects; furthermore, their handling is difficult and they are unsafe. We devised a new hemostatic agent comprising gelatin sponge and film designed to be applied to the bleeding site, thereby creating a topical hemostatic agent made of gelatin alone. The gelatin was prepared by alkali treatment to eliminate viral activity. Hemostatic effects, surgical handling, and tissue reactions of the materials, namely a two-layer sheet of gelatin, TachoSil, and gelatin sponge, were evaluated using 21 dogs' spleens. The two-layer gelatin sheet and gelatin sponge exhibited superior hemostatic effects (100% hemostasis completed) compared with TachoSil (0-17% hemostasis). The gelatin matrix immediately absorbed blood flowing from wounds and activated the autologous components in the absorbed blood that promoted coagulation at the bleeding site. The two-layer gelatin sheet had the best surgical handling among the evaluated materials. Materials made of gelatin were associated with fewer inflammatory reactions compared with materials of TachoSil. The two-layer sheet of gelatin is a useful topical agent because of its superior hemostatic effects and usability, and is associated with a lower risk of transmitting diseases and inflammatory reactions. Copyright © 2016. Published by Elsevier Taiwan.

  11. DETAIL OF TYPICAL WALL CONSTRUCTION IN COOLING ROOMS; TWO LAYERS ...

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

    DETAIL OF TYPICAL WALL CONSTRUCTION IN COOLING ROOMS; TWO LAYERS OF CORK INSULATION ARE ATTACHED TO REINFORCED CONCRETE WALL WITH WOOD SLEEPERS AND ASPHALT MASTIC; THIN, GLAZED TERRA-COTTA TILES PROTECT THE INSULATION INSIDE THE COOLER - Rath Packing Company, Hog Cutting Building, Sycamore Street between Elm & Eighteenth Streets, Waterloo, Black Hawk County, IA

  12. Two-layer contractive encodings for learning stable nonlinear features.

    PubMed

    Schulz, Hannes; Cho, Kyunghyun; Raiko, Tapani; Behnke, Sven

    2015-04-01

    Unsupervised learning of feature hierarchies is often a good strategy to initialize deep architectures for supervised learning. Most existing deep learning methods build these feature hierarchies layer by layer in a greedy fashion using either auto-encoders or restricted Boltzmann machines. Both yield encoders which compute linear projections of input followed by a smooth thresholding function. In this work, we demonstrate that these encoders fail to find stable features when the required computation is in the exclusive-or class. To overcome this limitation, we propose a two-layer encoder which is less restricted in the type of features it can learn. The proposed encoder is regularized by an extension of previous work on contractive regularization. This proposed two-layer contractive encoder potentially poses a more difficult optimization problem, and we further propose to linearly transform hidden neurons of the encoder to make learning easier. We demonstrate the advantages of the two-layer encoders qualitatively on artificially constructed datasets as well as commonly used benchmark datasets. We also conduct experiments on a semi-supervised learning task and show the benefits of the proposed two-layer encoders trained with the linear transformation of perceptrons.

  13. Protocol for carrying two-layer coded moving images

    NASA Astrophysics Data System (ADS)

    Ghanbari, M.; Azari, J.; Sarantopoulos, P.

    1995-05-01

    A modified version of the Orwell protocol is presented. While the presented method preserves all the basic features, it introduces the concept of the SURPLUS cell. These surplus cells enhance the performance of the network for class-2 traffic as well as those of the enhancement data in two-layer coded video by reducing the queuing delays. It is shown that the new method improves delay characteristics of the real-time services under mid-to-high traffic loads.

  14. Shapes of two-layer models of rotating planets

    NASA Astrophysics Data System (ADS)

    Kong, D.; Zhang, K.; Schubert, G.

    2010-12-01

    To first approximation the interiors of many planetary bodies consist of a core and mantle with significantly different densities. The shapes of the surface and interface between the core and the mantle are basic properties reflecting planetary structure and rotation. In addition, interface shape is an important parameter controlling the dynamics of a fluid core. We present a theory for the rotational distortion of a two-layer model of a planet (two-layer Maclaurin spheroid) that determines the shapes of both the interface and the outer free surface without treating departure from sphericity as a small perturbation. Since the interface and the outer free surface, in general, have different shapes, two different spheroidal coordinates are required in the mathematical analysis, and the transformation between them is at the heart of the complexity of the theory. Furthermore, two different cases have to be considered. In the first case, the core is sufficiently large, or the rate of rotation is sufficiently small, that the foci of the outer free surface are located within the core. In the second case, the core is sufficiently small, or the rate of rotation is sufficiently fast, that the foci of the free surface are located within the outer layer. In comparison to the classical Maclaurin solution which is explicitly analytical, the relevant multiple integrals for the equilibrium solution of a two-layer Maclaurin spheroid have to be evaluated numerically. The shape of a two-layer rotating planet is characterized by three dimensionless parameters that are explored systematically in the present study.

  15. High-temperature ''hydrostatic'' extrusion

    NASA Technical Reports Server (NTRS)

    Hunt, J. G.; Rice, R. W.

    1970-01-01

    Quasi-fluids permit hydrostatic extrusion of solid materials. The use of sodium chloride, calcium fluoride, or glasses as quasi-fluids reduces handling, corrosion, and sealing problems, these materials successfully extrude steel, molybdenum, ceramics, calcium carbonate, and calcium oxide. This technique also permits fluid-to-fluid extrusion.

  16. Dynamical criterion for a marginally unstable, quasi-linear behavior in a two-layer model

    NASA Technical Reports Server (NTRS)

    Ebisuzaki, W.

    1988-01-01

    A two-layer quasi-geostrophic flow forced by meridional variations in heating can be in regimes ranging from radiative equilibrium to forced geostrophic turbulence. Between these extremes is a regime where the time-mean (zonal) flow is marginally unstable. Using scaling arguments, it is concluded that such a marginally unstable state should occur when a certain parameter, measuring the strength of wave-wave interactions relative to the beta effect and advection by the thermal wind, is small. Numerical simulations support this proposal. A transition from the marginally unstable regime to a more nonlinear regime is then examined through numerical simulations with different radiative forcings. It is found that transition is not caused by secondary instability of waves in the marginally unstable regime. Instead, the time-mean flow can support a number of marginally unstable normal modes. These normal modes interact with each other, and if they are of sufficient amplitude, the flow enters a more nonlinear regime.

  17. The asymmetrically stepped, orifice compensated hydrostatic bearing

    NASA Astrophysics Data System (ADS)

    Scharrer, J. K.; Hibbs, R. I.; San Andres, L.

    1992-07-01

    An improved hydrostatic bedaring configuration consisting of a conventional orifice compensated, continuous, hydrostatic bearing augmented on one side by a ring with a smaller radial clearance is presented. Results for the leakage and rotordynamic coeffcients of this asymmetrically stepped hydrostatic bearing are calculated using a numerical solution of the film-average Navier-Stokes equations. Results of a parametric study on the effects of ring geometry and recess position on hydrostatic bearing performance are presented. The results show that the presence of the asymmetric step enhances the rotordynamic performance of an orifice compensated hydrostatic bearing.

  18. Theories of multiple equilibria and weather regimes : A critical reexamination. II - Baroclinic two-layer models

    NASA Technical Reports Server (NTRS)

    Cehelsky, Priscilla; Tung, Ka Kit

    1987-01-01

    Previous results based on low- and intermediate-order truncations of the two-layer model suggest the existence of multiple equilibria and/or multiple weather regimes for the extratropical large-scale flow. The importance of the transient waves in the synoptic scales in organizing the large-scale flow and in the maintenance of weather regimes was emphasized. The result shows that multiple equilibria/weather regimes that are present in lower-order models examined disappear when a sufficient number of modes are kept in the spectral expansion of the solution to the governing partial differential equations. Much of the chaotic behavior of the large-scale flow that is present in intermediate-order models is now found to be spurious. Physical reasons for the drastic modification are offered. A peculiarity in the formulation of most existing two-layer models is noted that also tends to exaggerate the importance of baroclinic processes and increase the degree of unpredictability of the large-scale flow.

  19. Two-layer model of coronary artery vasoactivity

    PubMed Central

    Huo, Yunlong; Zhao, Xuefeng; Cheng, Yana; Lu, Xiao

    2013-01-01

    Since vascular tone is regulated by smooth muscle cells in the media layer, a multilayer mechanical model is required for blood vessels. Here, we performed biaxial mechanical tests in the intima-media layer of right coronary artery to determine the passive and active properties in conjunction with the passive properties of adventitia for a full vessel wall model. A two-layer (intima-media and adventitia) model was developed to determine the transmural stress and stretch across the vessel wall. The mean ± SE values of the outer diameters of intima-media layers at transmural pressure of 60 mmHg in active state were 3.17 ± 0.16 and 3.07 ± 0.18 mm at axial stretch ratio of 1.2 and 1.3, respectively, which were significantly smaller than those in passive state (i.e., 3.62 ± 0.19 and 3.49 ± 0.22 mm, respectively, P < 0.05). The inner and outer diameters in no-load state of intima-media layers were 1.17 ± 0.09 and 2.08 ± 0.09 mm, respectively. The opening angles in zero-stress state had values of 159 ± 21° for intima-media layers and 98 ± 15° for adventitia layers, which suggests a residual strain between the two layers. There were slightly decreased active circumferential stresses (<10%), but significantly decreased active axial stresses (>25%) in the intima-media layer compared with those in the intact vessel. This suggests that the adventitia layer affects vascular contraction. The two-layer analysis showed that the intima-media layer bears the majority of circumferential tensions, in contrast to the adventitia layer, while contraction results in decreased stress and stretch in both layers. PMID:23471951

  20. Two-Layer Elastographic 3-D Traction Force Microscopy

    PubMed Central

    Álvarez-González, Begoña; Zhang, Shun; Gómez-González, Manuel; Meili, Ruedi; Firtel, Richard A.; Lasheras, Juan C.; del Álamo, Juan C.

    2017-01-01

    Cellular traction force microscopy (TFM) requires knowledge of the mechanical properties of the substratum where the cells adhere to calculate cell-generated forces from measurements of substratum deformation. Polymer-based hydrogels are broadly used for TFM due to their linearly elastic behavior in the range of measured deformations. However, the calculated stresses, particularly their spatial patterns, can be highly sensitive to the substratum’s Poisson’s ratio. We present two-layer elastographic TFM (2LETFM), a method that allows for simultaneously measuring the Poisson’s ratio of the substratum while also determining the cell-generated forces. The new method exploits the analytical solution of the elastostatic equation and deformation measurements from two layers of the substratum. We perform an in silico analysis of 2LETFM concluding that this technique is robust with respect to TFM experimental parameters, and remains accurate even for noisy measurement data. We also provide experimental proof of principle of 2LETFM by simultaneously measuring the stresses exerted by migrating Physarum amoeboae on the surface of polyacrylamide substrata, and the Poisson’s ratio of the substrata. The 2LETFM method could be generalized to concurrently determine the mechanical properties and cell-generated forces in more physiologically relevant extracellular environments, opening new possibilities to study cell-matrix interactions. PMID:28074837

  1. Two-Layer Elastographic 3-D Traction Force Microscopy

    NASA Astrophysics Data System (ADS)

    Álvarez-González, Begoña; Zhang, Shun; Gómez-González, Manuel; Meili, Ruedi; Firtel, Richard A.; Lasheras, Juan C.; Del Álamo, Juan C.

    2017-01-01

    Cellular traction force microscopy (TFM) requires knowledge of the mechanical properties of the substratum where the cells adhere to calculate cell-generated forces from measurements of substratum deformation. Polymer-based hydrogels are broadly used for TFM due to their linearly elastic behavior in the range of measured deformations. However, the calculated stresses, particularly their spatial patterns, can be highly sensitive to the substratum’s Poisson’s ratio. We present two-layer elastographic TFM (2LETFM), a method that allows for simultaneously measuring the Poisson’s ratio of the substratum while also determining the cell-generated forces. The new method exploits the analytical solution of the elastostatic equation and deformation measurements from two layers of the substratum. We perform an in silico analysis of 2LETFM concluding that this technique is robust with respect to TFM experimental parameters, and remains accurate even for noisy measurement data. We also provide experimental proof of principle of 2LETFM by simultaneously measuring the stresses exerted by migrating Physarum amoeboae on the surface of polyacrylamide substrata, and the Poisson’s ratio of the substrata. The 2LETFM method could be generalized to concurrently determine the mechanical properties and cell-generated forces in more physiologically relevant extracellular environments, opening new possibilities to study cell-matrix interactions.

  2. Two-Layer Elastographic 3-D Traction Force Microscopy.

    PubMed

    Álvarez-González, Begoña; Zhang, Shun; Gómez-González, Manuel; Meili, Ruedi; Firtel, Richard A; Lasheras, Juan C; Del Álamo, Juan C

    2017-01-11

    Cellular traction force microscopy (TFM) requires knowledge of the mechanical properties of the substratum where the cells adhere to calculate cell-generated forces from measurements of substratum deformation. Polymer-based hydrogels are broadly used for TFM due to their linearly elastic behavior in the range of measured deformations. However, the calculated stresses, particularly their spatial patterns, can be highly sensitive to the substratum's Poisson's ratio. We present two-layer elastographic TFM (2LETFM), a method that allows for simultaneously measuring the Poisson's ratio of the substratum while also determining the cell-generated forces. The new method exploits the analytical solution of the elastostatic equation and deformation measurements from two layers of the substratum. We perform an in silico analysis of 2LETFM concluding that this technique is robust with respect to TFM experimental parameters, and remains accurate even for noisy measurement data. We also provide experimental proof of principle of 2LETFM by simultaneously measuring the stresses exerted by migrating Physarum amoeboae on the surface of polyacrylamide substrata, and the Poisson's ratio of the substrata. The 2LETFM method could be generalized to concurrently determine the mechanical properties and cell-generated forces in more physiologically relevant extracellular environments, opening new possibilities to study cell-matrix interactions.

  3. Viscoelasticity of two-layer vesicles in solution

    NASA Astrophysics Data System (ADS)

    Lu, C.-Y. David; Komura, Shigeyuki; Seki, Kazuhiko

    2012-12-01

    The dynamic shape relaxation of the two-layer vesicle is calculated. In addition to the undulation relaxation where the two bilayers move in the same direction, the squeezing mode appears when the gap between the two bilayers is small. At a large gap, the inner vesicle relaxes much faster, whereas the slow mode is mainly due to the outer-layer relaxation. We have calculated the viscoelasticity of the dilute two-layer-vesicle suspension. It is found that for a small gap, the applied shear drives the undulation mode strongly while the slow squeezing mode is not much excited. In this limit, the complex viscosity is dominated by the fast-mode contribution. On the other hand, the slow mode is strongly driven by shear for a larger gap. We have determined the crossover gap, which depends on the interaction between the two bilayers. For a series of samples where the gap is changed systematically, it is possible to observe the two amplitude switchings.

  4. Enhancing Traffic Capacity of Two-Layer Complex Networks

    NASA Astrophysics Data System (ADS)

    Jiang, Zhong-Yuan; Liang, Man-Gui; Zhang, Shuai; Zhou, Weixing; Jin, Huiqin

    2013-08-01

    As two-layer or multi-layer network model can more accurately reveal many real structures of complex systems such as peer-to-peer (P2P) networks on IP networks, to better understand the traffic dynamics and improve the network traffic capacity, we propose to efficiently construct the structure of upper logical layer network which can be possibly implemented. From the beginning, we assume that the logical layer network has the same structure as the lower physical layer network, and then we use link-removal strategy in which a fraction of links with maximal product (ki* kj) are removed from the logical layer, where ki and kj are the degrees of node i and node j, respectively. Traffic load is strongly redistributed from center nodes to noncenter nodes. The traffic capacity of whole complex system is enhanced several times at the expense of a little average path lengthening. In two-layer network model, the physical layer network structure is unchanged and the shortest path routing strategy is used. The structure of upper layer network can been constructed freely under our own methods. This mechanism can be employed in many real complex systems to improve the network traffic capacity.

  5. Spatial frequency domain spectroscopy of two layer media

    NASA Astrophysics Data System (ADS)

    Yudovsky, Dmitry; Durkin, Anthony J.

    2011-10-01

    Monitoring of tissue blood volume and oxygen saturation using biomedical optics techniques has the potential to inform the assessment of tissue health, healing, and dysfunction. These quantities are typically estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in superficial tissue such as the skin can be confounded by the strong absorption of melanin in the epidermis. Furthermore, epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. This study describes a technique for decoupling the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. An artificial neural network was used to map input optical properties to spatial frequency domain diffuse reflectance of two layer media. Then, iterative fitting was used to determine the optical properties from simulated spatial frequency domain diffuse reflectance. Additionally, an artificial neural network was trained to directly map spatial frequency domain reflectance to sets of optical properties of a two layer medium, thus bypassing the need for iteration. In both cases, the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis were determined independently. The accuracy and efficiency of the iterative fitting approach was compared with the direct neural network inversion.

  6. Worm Gear With Hydrostatic Engagement

    NASA Technical Reports Server (NTRS)

    Chaiko, Lev I.

    1994-01-01

    In proposed worm-gear transmission, oil pumped at high pressure through meshes between teeth of gear and worm coil. Pressure in oil separates meshing surfaces slightly, and oil reduces friction between surfaces. Conceived for use in drive train between gas-turbine engine and rotor of helicopter. Useful in other applications in which weight critical. Test apparatus simulates and measures some loading conditions of proposed worm gear with hydrostatic engagement.

  7. Worm Gear With Hydrostatic Engagement

    NASA Technical Reports Server (NTRS)

    Chaiko, Lev I.

    1994-01-01

    In proposed worm-gear transmission, oil pumped at high pressure through meshes between teeth of gear and worm coil. Pressure in oil separates meshing surfaces slightly, and oil reduces friction between surfaces. Conceived for use in drive train between gas-turbine engine and rotor of helicopter. Useful in other applications in which weight critical. Test apparatus simulates and measures some loading conditions of proposed worm gear with hydrostatic engagement.

  8. Mass transfer model for two-layer TBP oxidation reactions

    SciTech Connect

    Laurinat, J.E.

    1994-09-28

    To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments. Three cases were investigated: (1) transfer of water into the TBP layer with sparging of both the aqueous and TBP layers, (2) transfer of water into the TBP layer with sparging of just the TBP layer, and (3) transfer of butanol into the aqueous layer with sparging of both layers. The TBP layer was comprised of 99% pure TBP (spiked with butanol for the butanol transfer experiments), and the aqueous layer was comprised of either water or an aluminum nitrate solution. The liquid layers were air sparged to simulate the mixing due to the evolution of gases generated by oxidation reactions. A plastic tube and a glass frit sparger were used to provide different size bubbles. Rates of mass transfer were measured using infrared spectrophotometers provided by SRTC/Analytical Development.

  9. Experiments on two-layer density-stratified inertial gravity currents

    NASA Astrophysics Data System (ADS)

    Dai, Albert

    2017-07-01

    Experiments for the gravity currents produced from a two-layer density-stratified buoyancy source in a full-depth, lock-exchange setup with a scaling analysis describing the flow morphologies are presented. In the inertial phase of propagation, the 3 /2 power relationship xf3 /2=1.5 FIB01 /2(t +tI) robustly applies between the front location xf and time t , where FI is the Froude number in the inertial phase, B0 is the total released buoyancy, and tI is the t -intercept. We showed that the Froude number in the inertial phase is not a universal constant but depends on the two controlling parameters, namely, the density difference ratio, Rρ=(ρU-ρ0) /(ρL-ρ0) , where ρU,ρL, and ρ0 are the densities of the fluids in the upper layer, lower layer, and ambient environment, respectively, and the buoyancy distribution parameter, RB=BU/B0 , where BU is the buoyancy in the upper layer. For a given buoyancy distribution parameter, the Froude number in the inertial phase decreases monotonically as the density difference ratio decreases. For a given density difference ratio, the Froude number in the inertial phase has a local minimum as the buoyancy distribution parameter falls in the range of 0.3 ≲RB≲0.5 . When the buoyancy source is homogeneous, the Froude number in the inertial phase has its maximum value at FI=1.33 ±0.02 . The flow morphology is also found to depend on the two controlling parameters. For weakly stratified two-layer heavy fluid, 0.4 ≲Rρ<1 , mixing between the fluids from the two layers is more immediate. For strongly stratified two-layer heavy fluid, 0 flows dominated by the upper layer, RB→1 , and for flows dominated by the lower layer, RB→0 . For gravity currents that are produced from a strongly stratified source and dominated by the upper layer, the upper layer may override and outrun the lower layer, which initially takes the lead after the two-layer heavy fluid is released. For

  10. Effects of plasma spray parameters on two layer thermal barrier

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1981-01-01

    The power level and the type of arc gas used during plasma spraying of a two layer thermal barrier system (TBS) were found to affect the life of the system. Life at 1095 C in a cyclic furnace test was improved by about 140 percent by increasing the power during plasma spray applications of the bond and thermal barrier coatings. This improvement is due to increases in the densities of the bond and thermal barrier coatings by 3 and 5 percent, respectively. These increases in densities are equivalent to about 45 and 30 percent reduction in mean porosities, respectively. The addition of hydrogen to the argon arc gas had the same effect as the reduction in power level and caused a reduction in TBS life.

  11. Two-layer thermal barrier coating for high temperature components

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1977-01-01

    A simple two-layer plasma-sprayed thermal barrier coating system was developed which has the potential for protecting high temperature air-cooled gas turbine components. Of the initially examined coatings, the most promising system is an Ni-16Cr-6Al-0.6Y (in wt%) bond coating (about 0.005 to 0.010 cm thick) and a ZrO2-12Y2O3 (in wt%) thermal barrier coating (about 0.025 to 0.064 cm thick). This thermal barrier substantially lowered the metal temperature of the air-cooled airfoil. The coating withstood 3200 cycles (80 s at 1280 C surface temperature) and 275 cycles (1 hr at 1490 C surface temperature) without cracking or spalling. No separation of the thermal barrier from the bond coating or the bond coating from the substrate was observed.

  12. ANSYS Modeling of Hydrostatic Stress Effects

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.

    1999-01-01

    Classical metal plasticity theory assumes that hydrostatic pressure has no effect on the yield and postyield behavior of metals. Plasticity textbooks, from the earliest to the most modem, infer that there is no hydrostatic effect on the yielding of metals, and even modem finite element programs direct the user to assume the same. The object of this study is to use the von Mises and Drucker-Prager failure theory constitutive models in the finite element program ANSYS to see how well they model conditions of varying hydrostatic pressure. Data is presented for notched round bar (NRB) and "L" shaped tensile specimens. Similar results from finite element models in ABAQUS are shown for comparison. It is shown that when dealing with geometries having a high hydrostatic stress influence, constitutive models that have a functional dependence on hydrostatic stress are more accurate in predicting material behavior than those that are independent of hydrostatic stress.

  13. ANSYS Modeling of Hydrostatic Stress Effects

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.

    1999-01-01

    Classical metal plasticity theory assumes that hydrostatic pressure has no effect on the yield and postyield behavior of metals. Plasticity textbooks, from the earliest to the most modem, infer that there is no hydrostatic effect on the yielding of metals, and even modem finite element programs direct the user to assume the same. The object of this study is to use the von Mises and Drucker-Prager failure theory constitutive models in the finite element program ANSYS to see how well they model conditions of varying hydrostatic pressure. Data is presented for notched round bar (NRB) and "L" shaped tensile specimens. Similar results from finite element models in ABAQUS are shown for comparison. It is shown that when dealing with geometries having a high hydrostatic stress influence, constitutive models that have a functional dependence on hydrostatic stress are more accurate in predicting material behavior than those that are independent of hydrostatic stress.

  14. Static Characteristics of Conical Hydrostatic Journal Bearing Under Micropolar Lubrication

    NASA Astrophysics Data System (ADS)

    Rana, N. K.; Gautam, S. S.; Verma, S.

    2014-10-01

    A theoretical analysis for static characteristics of a conical hydrostatic journal bearing for a multirecess constant flow valve compensated under micropolar lubrication has been carried out in this work. The numerical solution of the modified Reynolds equation for the conical bearing has been done using Finite Element Method (FEM) using necessary boundary conditions. The various static characteristics have been presented to analyze the performance of bearing at zero speed.

  15. Nonlinear internal wave at the interface of two-layer liquid due to a moving hydrofoil

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Wu, Changhong; Zou, Li; Wang, Qianxi; Ding, Qi

    2017-07-01

    This paper is concerned with the internal wave at the interface of two layers of liquids due to a hydrofoil in the lower layer liquid. The two-layer fluid is assumed moving parallel to the interface at different velocities. The stratified flow is modeled based on the incompressible potential flow theory, with the nonlinear boundary conditions at the interface. Boundary integral equations are formulated for the fully nonlinear interfacial wave generated by the hydrofoil. The numerical model results in a set of nonlinear algebra equations, which are solved using the quasi-Newton method. We show that the quasi-Newton method is more efficient than Newton's method, which is often used for solving these types of equations in the literature. The wave profiles were analyzed in terms of the location and thickness of the hydrofoil, the Froude number, and the ratio of the densities of the two fluids. The computations show that the interfacial wave amplitude showed a trend first of increase and then of decrease with the distance between the hydrofoil and the still interface.

  16. Switching skeletons: hydrostatic support in molting crabs

    NASA Technical Reports Server (NTRS)

    Taylor, Jennifer R A.; Kier, William M.; Walker, I. D. (Principal Investigator)

    2003-01-01

    Skeletal support systems are essential for support, movement, muscular antagonism, and locomotion. Crustaceans shed their rigid exoskeleton at each molt yet are still capable of forceful movement. We hypothesize that the soft water-inflated body of newly molted crabs may rely on a hydrostatic skeleton, similar to that of worms and polyps. We measured internal hydrostatic pressure and the force exerted during claw adduction and observed a strong correlation between force and hydrostatic pressure, consistent with hydrostatic skeletal support. This alternation between the two basic skeletal types may be widespread among arthropods.

  17. Switching skeletons: hydrostatic support in molting crabs

    NASA Technical Reports Server (NTRS)

    Taylor, Jennifer R A.; Kier, William M.; Walker, I. D. (Principal Investigator)

    2003-01-01

    Skeletal support systems are essential for support, movement, muscular antagonism, and locomotion. Crustaceans shed their rigid exoskeleton at each molt yet are still capable of forceful movement. We hypothesize that the soft water-inflated body of newly molted crabs may rely on a hydrostatic skeleton, similar to that of worms and polyps. We measured internal hydrostatic pressure and the force exerted during claw adduction and observed a strong correlation between force and hydrostatic pressure, consistent with hydrostatic skeletal support. This alternation between the two basic skeletal types may be widespread among arthropods.

  18. PELLISSIER H5 HYDROSTATIC LEVEL

    SciTech Connect

    Imfeld, Hans L.

    2003-05-01

    Conventional spirit leveling using double scale invar rods has been in use at SLAC for some time as the standard method of obtaining very precise height difference information. Typical accuracy of {+-} 100 {micro}m and better can routinely be achieved. Procedures and software have evolved to the point where the method is relatively fast and reliable. However, recent projects such as the Final Focus Test Beam have pushed the requested vertical positioning tolerances for alignment of quadrupoles to the 30 {mu}m level. It is apparent that conventional spirit leveling cannot achieve this level of accuracy. To meet the challenge, the alignment group contracted with Pellissier, Inc. to develop a portable hydrostatic leveling system. The H5 grew out of this development effort and is expected to provide the needed accuracy and ease of use required for such vertical positioning projects. The H5 hydrostatic level is a portable instrument that under ideal operating conditions will provide elevation differences with an accuracy of +/- 5 {mu}m over double leg closed loop surveys. The H5 incorporates several features that eliminate problems common with hydrostatic leveling, primarily errors due to thermal gradients along the fluid tube. It utilizes self-checking software and automatic water level detection to reduce observational errors. Design features also have made the instrument reasonably quick and easy to operate when used on a flat surface. The instrument can be adapted for use in a wide variety of environments by using support fixtures and brackets. The H5 is robust and operators require little training to become proficient in its use. It has been successfully employed on several projects including the FFTB project at SLAC, as well as the Green Bank Telescope project for the NRAO and the SSC project in Texas.

  19. Hydrostatic Hyperbaric Chamber Ventilation System

    NASA Technical Reports Server (NTRS)

    Sargusingh, Miriam M.

    2011-01-01

    The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications, including the treatment of medical conditions. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy available in the developing world for the treatment of a variety of medical conditions. Specifically, hyperbaric oxygen therapy is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. Hyperbaric oxygen therapy is simply too expensive and too dangerous to implement in the developing world using standard equipment. The hydrostatic hyperbaric chamber technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system that will provide controlled pressurization of the system, and provide adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the

  20. A global-scale two-layer transient groundwater model: Development and application to groundwater depletion

    NASA Astrophysics Data System (ADS)

    de Graaf, Inge E. M.; van Beek, Rens L. P. H.; Gleeson, Tom; Moosdorf, Nils; Schmitz, Oliver; Sutanudjaja, Edwin H.; Bierkens, Marc F. P.

    2017-04-01

    Groundwater is the world's largest accessible source of freshwater to satisfy human water needs. Moreover, groundwater buffers variable precipitation rates over time, thereby effectively sustaining river flows in times of droughts and evaporation in areas with shallow water tables. In this study, building on previous work, we simulate groundwater head fluctuations and groundwater storage changes in both confined and unconfined aquifer systems using a global-scale high-resolution (5‧) groundwater model by deriving new estimates of the distribution and thickness of confining layers. Inclusion of confined aquifer systems (estimated 6-20% of the total aquifer area) improves estimates of timing and amplitude of groundwater head fluctuations and changes groundwater flow paths and groundwater-surface water interaction rates. Groundwater flow paths within confining layers are shorter than paths in the underlying aquifer, while flows within the confined aquifer can get disconnected from the local drainage system due to the low conductivity of the confining layer. Lateral groundwater flows between basins are significant in the model, especially for areas with (partially) confined aquifers were long flow paths crossing catchment boundaries are simulated, thereby supporting water budgets of neighboring catchments or aquifer systems. The developed two-layer transient groundwater model is used to identify hot-spots of groundwater depletion. Global groundwater depletion is estimated as 7013 km3 (137 km3y-1) over 1960-2010, which is consistent with estimates of previous studies.

  1. Zonostrophic Turbulence in Two-layer Quasi-geotrophic Model

    NASA Astrophysics Data System (ADS)

    Chai, J.; Jansen, M.; Vallis, G. K.

    2015-12-01

    Zonostrophic turbulence was discovered in the one-layer shallow water model forced by random stirring and has since been related to Jovian atmosphere for the appearance of very strong and steady zonal jets. This study shows that such zonostrophic turbulence can also exist in a two-layer QG model driven by baroclinic instability. The kinetic energy spectrum shows a clear transition from the inertial inverse cascade regime with energy spectrum slope -5/3 at small scales to the zonostrophic regime with slope -5 at the largest scales. The turbulent regime is characterized by two non-dimensional numbers criticality and non-dimensional surface friction. The zonostrophic regime is reached and is most clear in the corner of low friction and low criticality. A new dependency of eddy diffusivity on surface friction is founded when surface friction is low enough, that eddy diffusivity decreases with surface friction regardless of criticality. The zonal jets are found to be strong mixing barriers, especially in the upper layer, and therefore potential vorticity (PV) and tracer staircases are formed. Time-space spectrum shows that the strong zonal jet traps waves within the critical latitudes so that the waves do not break. The longest waves are trapped as edge waves, and the shorter waves are trapped by Rossby wave reflection. Both are a result of the PV gradient created by the jet core.

  2. In vivo spatial frequency domain spectroscopy of two layer media

    NASA Astrophysics Data System (ADS)

    Yudovsky, Dmitry; Nguyen, John Quan M.; Durkin, Anthony J.

    2012-10-01

    Monitoring of tissue blood volume and local oxygen saturation can inform the assessment of tissue health, healing, and dysfunction. These quantities can be estimated from the contribution of oxyhemoglobin and deoxyhemoglobin to the absorption spectrum of the dermis. However, estimation of blood related absorption in skin can be confounded by the strong absorption of melanin in the epidermis and epidermal thickness and pigmentation varies with anatomic location, race, gender, and degree of disease progression. Therefore, a method is desired that decouples the effect of melanin absorption in the epidermis from blood absorption in the dermis for a large range of skin types and thicknesses. A previously developed inverse method based on a neural network forward model was applied to simulated spatial frequency domain reflectance of skin for multiple wavelengths in the near infrared. It is demonstrated that the optical thickness of the epidermis and absorption and reduced scattering coefficients of the dermis can be determined independently and with minimal coupling. Then, the same inverse method was applied to reflectance measurements from a tissue simulating phantom and in vivo human skin. Oxygen saturation and total hemoglobin concentrations were estimated from the volar forearms of weakly and strongly pigmented subjects using a standard homogeneous model and the present two layer model.

  3. Hydrostatic compaction of Microtherm HT.

    SciTech Connect

    Broome, Scott Thomas; Bauer, Stephen J.

    2010-09-01

    Two samples of jacketed Microtherm{reg_sign}HT were hydrostatically pressurized to maximum pressures of 29,000 psi to evaluate both pressure-volume response and change in bulk modulus as a function of density. During testing, each of the two samples exhibited large irreversible compactive volumetric strains with only small increases in pressure; however at volumetric strains of approximately 50%, the Microtherm{reg_sign}HT stiffened noticeably at ever increasing rates. At the maximum pressure of 29,000 psi, the volumetric strains for both samples were approximately 70%. Bulk modulus, as determined from hydrostatic unload/reload loops, increased by more than two-orders of magnitude (from about 4500 psi to over 500,000 psi) from an initial material density of {approx}0.3 g/cc to a final density of {approx}1.1 g/cc. An empirical fit to the density vs. bulk modulus data is K = 492769{rho}{sup 4.6548}, where K is the bulk modulus in psi, and {rho} is the material density in g/cm{sup 3}. The porosity decreased from 88% to {approx}20% indicating that much higher pressures would be required to compact the material fully.

  4. 46 CFR 64.83 - Hydrostatic test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... on the metal identification plate without leaking; and (6) If fitted with an internal heating coil, the heating coil passing a hydrostatic test at a pressure of 200 psig or more or 50 percent or more above the rated pressure of the coil, whichever is greater. (b) If the tank passes the hydrostatic...

  5. Designing Two-Layer Optical Networks with Statistical Multiplexing

    NASA Astrophysics Data System (ADS)

    Addis, B.; Capone, A.; Carello, G.; Malucelli, F.; Fumagalli, M.; Pedrin Elli, E.

    The possibility of adding multi-protocol label switching (MPLS) support to transport networks is considered an important opportunity by telecom carriers that want to add packet services and applications to their networks. However, the question that arises is whether it is suitable to have MPLS nodes just at the edge of the network to collect packet traffic from users, or also to introduce MPLS facilities on a subset of the core nodes in order to exploit packet switching flexibility and multiplexing, thus providing induction of a better bandwidth allocation. In this article, we address this complex decisional problem with the support of a mathematical programming approach. We consider two-layer networks where MPLS is overlaid on top of transport networks-synchronous digital hierarchy (SDH) or wavelength division multiplexing (WDM)-depending on the required link speed. The discussions' decisions take into account the trade-off between the cost of adding MPLS support in the core nodes and the savings in the link bandwidth allocation due to the statistical multiplexing and the traffic grooming effects induced by MPLS nodes. The traffic matrix specifies for each point-to-point request a pair of values: a mean traffic value and an additional one. Using this traffic model, the effect of statistical multiplexing on a link allows the allocation of a capacity equal to the sum of all the mean values of the traffic demands routed on the link and only the highest additional one. The proposed approach is suitable to solve real instances in reasonable time.

  6. Schumann Resonances on Mars - a Two-layer Ground Case

    NASA Astrophysics Data System (ADS)

    Kozakiewicz, J.; Kulak, A.; Mlynarczyk, J.

    2012-04-01

    Schumann resonances (SR) are global resonances of electromagnetic waves in the range of extremely low frequencies (ELF) propagating in a cavity formed by a planetary surface and a lower ionosphere. SR are induced by electrical discharges, which on Earth are associated mainly with lightning. They were predicted by Winfried Otto Schumann in 1952. SR are supposed to occur on Mars, although many properties of the Martian environment are still unknown. One of the most important problems in modeling SR on Mars is to estimate electrical properties of the Martian ground and their influence on ELF waves propagation. The Martian crust is composed mainly of basaltic materials. Water, which causes significant increase in electrical conductivity of rocks, does not exist in liquid state at the surface of Mars. Therefore the Martian ground is believed to be a low conductive one. However, it is possible that some liquid water may be present at various depths below the surface. In our previous study we have developed an analytical model, based on the characteristic electric and magnetic altitudes' formalism, that has allowed us to take into consideration the Martian ground. Using this new model, we found that basaltic ground of low conductivity greatly influenced the SR parameters. In this work, we carried out simulations in order to characterize an influence of vertical changes in ground properties on the parameters of the Martian ground-ionosphere waveguide. We have considered several cases of a two-layer ground, in which the lower layer was of higher conductivity than the upper one. The obtained results indicate how the SR parameters depend on electrical conductivity, permittivity, and depth of the layers. The results also point out the importance of studying SR on Mars and the need for further research in propagation of ELF waves in the Martian environment. SR can be used as a remote sensing tool for exploration of the Martian crust. Furthermore, they can be especially useful

  7. Traffic dynamics on two-layer complex networks with limited delivering capacity

    NASA Astrophysics Data System (ADS)

    Ma, Jinlong; Han, Weizhan; Guo, Qing; Wang, Zhenyong

    2016-08-01

    The traffic dynamics of multi-layer networks has attracted a great deal of interest since many real networks are comprised of two or more layers of subnetworks. Due to its low traffic capacity, the average delivery capacity allocation strategy is susceptible to congestion with the wildly used shortest path routing protocol on two-layer complex networks. In this paper, we introduce a delivery capacity allocation strategy into the traffic dynamics on two-layer complex networks and focus on its effect on the traffic capacity measured by the critical point Rc of phase transition from free flow to congestion. When the total nodes delivering capacity is fixed, the delivering capacity of each node in physical layer is assigned to the degree distributions of both the physical and logical layers. Simulation results show that the proposed strategy can bring much better traffic capacity than that with the average delivery capacity allocation strategy. Because of the significantly improved traffic performance, this work may be useful for optimal design of networked traffic dynamics.

  8. Fluid Compressibility Effects on the Dynamic Response of Hydrostatic Journal Bearings

    NASA Technical Reports Server (NTRS)

    Sanandres, Luis A.

    1991-01-01

    A theoretical analysis for the dynamic performance characteristics of laminar flow, capillar/orifice compensated hydrostatic journal bearings is presented. The analysis considers in detail the effect of fluid compressibility in the bearing recesses. At high frequency excitations beyond a break frequency, the bearing hydrostatic stiffness increases sharply and it is accompanied by a rapid decrease in direct damping. Also, the potential of pneumatic hammer instability (negative damping) at low frequencies is likely to occur in hydrostatic bearing applications handling highly compressible fluids. Useful design criteria to avoid undesirable dynamic operating conditions at low and high frequencies are determined. The effect of fluid recess compressibility is brought into perspective, and found to be of utmost importance on the entire frequency spectrum response and stability characteristics of hydrostatic/hybrid journal bearings.

  9. Mathematical model of two-layer in pipe

    NASA Astrophysics Data System (ADS)

    Matveev, Sergey K.; Jaichibekov, Nurbulat Zh.; Shalabayeva, Bakyt S.

    2017-09-01

    The problem of stationary turbulent flow in an inclined pipe of two immiscible liquids is solving. The formulation and method of solving the problem are close to our previous works, but the flow is turbulent. At the phase surface (y = h, h is the depth of the lower layer of the liquid) axial velocity w, frictional stress and turbulent viscosity νt are assumed to be continuous, the densities ρi and molecular viscosities νi are different for i = 1 (y ≤ h) and for i = 2 (y ≥ h). The equations of momentum in each layer and the equation for turbulent viscosity are numerically solved. At moderate Reynolds numbers, the regimes were observed in the calculations when in a layer with a small volume fraction the flow became laminar with turbulent flow in the second layer.

  10. Hydrostatic Hyperbaric Chamber Ventilation System

    NASA Technical Reports Server (NTRS)

    Sarguisingh, Miriam J.

    2012-01-01

    The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware

  11. A Hydrostatic Bearing Test System for Measuring Bearing Load Using Magnetic-Fluid Lubricants.

    PubMed

    Weng, Huei Chu; Chen, Lu-Yu

    2016-05-01

    This paper conducts a study on the design of a hydrostatic bearing test system. It involves the determination of viscous properties of magnetic-fluid lubricants. The load of a hydrostatic thrust bearing using a water-based magnetite nanofluid of varying volume flow rate is measured under an applied external induction field via the test system. Results reveal that the presence of nanoparticles in a carrier liquid would cause an enhanced bearing load. Such an effect could be further magnified by increasing the lubricant volume flow rate or the external induction field strength.

  12. Hybrid Hydrostatic/Transient Roller Bearing Assembly

    NASA Technical Reports Server (NTRS)

    Justak, John F.

    1992-01-01

    Proposed bearing assembly for shaft of high-speed turbopump includes both hydrostatic and rolling-element bearings. Rolling-element bearing unloaded at high speed by centrifugal expansion of outer race and transient retainer.

  13. A two-layer depth-averaged approach to describe the regime stratification in collapses of dry granular columns

    NASA Astrophysics Data System (ADS)

    Sarno, L.; Carravetta, A.; Martino, R.; Tai, Y. C.

    2014-10-01

    The dynamics of dry granular flows is still insufficiently understood. Several depth-averaged approaches, where the flow motion is described through hydrodynamic-like models with suitable resistance laws, have been proposed in the last decades to describe the propagation of avalanches and debris flows. Yet, some important features of the granular flow dynamics cannot be well delivered. For example, it is very challenging to capture the progressive deposition process, observed in collapses and dam-break flows over rough beds, where an upper surface flow is found to coexist with a lower creeping flow. The experimental observations of such flows suggest the existence of a flow regime stratification caused by different momentum transfer mechanisms. In this work, we propose a two-layer depth-averaged model, aiming at describing such a stratification regime inside the flowing granular mass. The model equations are derived for both two-dimensional plane and axi-symmetric flows. Mass and momentum balances of each layer are considered separately, so that different constitutive laws are introduced. The proposed model is equipped with a closure equation accounting for the mass flux at the interface between the layers. Numerical results are compared with experimental data of axi-symmetric granular collapses to validate the proposed approach. The model delivers sound agreement with experimental data when the initial aspect ratios are small. In case of large initial aspect ratios, it yields a significant improvement in predicting the final shape of deposit and also the run-out distances. Further comparisons with different numerical models show that the two-layer approach is capable of correctly describing the main features of the final deposit also in the case of two-dimensional granular collapses.

  14. Hydrostatic Stress Effects in Metal Plasticity

    NASA Technical Reports Server (NTRS)

    Wilson, Christopher D.

    1999-01-01

    Since the 1940s, the theory of plasticity has assumed that hydrostatic stress does not affect the yield or postyield behavior of metals. This assumption is based on the early work of Bridgman. Bridgman found that hydrostatic pressure (compressive stress) does not affect yield behavior until a substantial amount of pressure (greater than 100 ksi) is present. The objective of this study was to determine the effect of hydrostatic tension on yield behavior. Two different specimen geometries were examined: an equal-arm bend specimen and a double edge notch specimen. The presence of a notch is sufficient to develop high enough hydrostatic tensile stresses to affect yield. The von Mises yield function, which does not have a hydrostatic component, and the Drucker-Prager yield function, which includes a hydrostatic component, were used in finite element analyses of the two specimen geometries. The analyses were compared to test data from IN 100 specimens. For both geometries, the analyses using the Drucker-Prager yield function more closely simulated the test data. The von Mises yield function lead to 5-10% overprediction of the force-displacement or force-strain response of the test specimens.

  15. A Theory for the Emergence of Coherent Structures in a Quasi-Geostrophic Two Layer Model

    NASA Astrophysics Data System (ADS)

    Bakas, N.; Ioannou, P. J.

    2016-12-01

    Turbulent flows are observed to be self-organized into large scale structures such as zonal jets and coherent vortices. We investigate turbulence organization in a quasi-geostrophic two layer model in the limit of weak baroclinicity in which turbulence is sustained by random stirring. Direct numerical simulations of this model show that as the energy input rate of the forcing is increased there are two regime transitions in the flow. First, the homogeneity of the flow is broken by the emergence of non-zonal, coherent, westward propagating waves. For larger energy input rates zonal jets emerge and are observed to co-exist with large scale waves. We use a non-equilibrium statistical theory, Stochastic Structural Stability Theory (S3T), to address the emergence of these coherent structures for a wide range of parameters. Employing the tools of S3T, we construct a coupled dynamical system that describes the statistical state dynamics of the flow. We then treat the structural stability of a homogeneous equilibrium with no mean flow analytically. We find that coherent waves and zonal jets appear as a result of the structure forming instability of the statistical state dynamics and equilibrate at finite amplitude. Comparison of the predictions of S3T with the direct numerical simulations show that S3T accurately predicts the critical energy input rates for the emergence of both coherent waves and zonal jets in the non-linear simulations as well as the characteristics (scale, amplitude and phase speed) of these structures.

  16. Two-layer viscous instability in a rotating couette device

    NASA Technical Reports Server (NTRS)

    Gallagher, Christopher; Kropnewicki, Tom; Leighton, David T.; Mccready, Mark J.

    1994-01-01

    A novel experiment to study the interfacial shear instability between two liquids is described. Density-matched immiscible liquids are confined between concentric cylinders such that the interface is parallel to the cylinder walls. Interfacial waves that develop because of viscosity differences between the shearing fluids are studied as a function of rotation rate and depth ratio using optical techniques. Conditions neutral stability and the most unstable wavenumber agree reasonably well with predictions from linear stability analysis of the Navier-Stokes equations. Illumination using laser sheets allows precise measurement of the interface shape. Future experiments will verify the correctness of weakly nonlinear theories that describe energy transfer and saturation of wave growth by nonlinear effects. Measurements of solitary wave shapes, that occur far above neutral stability, will be compared to similar measurements for systems that have gravity as an important force to determine how gravity effects large disturbances. These results will be used to interpret slug and annular flow data that have been obtained in other mu g studies.

  17. Dynamic Cores in Hydrostatic Disguise

    NASA Astrophysics Data System (ADS)

    Ballesteros-Paredes, Javier; Klessen, Ralf S.; Vázquez-Semadeni, Enrique

    2003-07-01

    project are small (<~0.18 pc). As a consequence, different projections of the same core may give very different values of the BE fits. Finally, we briefly discuss recent results claiming that Bok globule B68 is in hydrostatic equilibrium, stressing that they imply that this core is unstable by a wide margin. We conclude that fitting BE profiles to observed cores is not an unambiguous test of hydrostatic equilibrium and that fit-estimated parameters such as mass, central density, density contrast, temperature, or radial profile of the BE sphere may differ significantly from the actual values in the cores.

  18. Evaluation of a hybrid hydrostatic bearing for cryogenic turbopump application

    NASA Technical Reports Server (NTRS)

    Spica, P. W.; Hannum, N. P.; Meyer, S. D.

    1986-01-01

    A hybrid hydrostatic bearing was designed to operate in liquid hydrogen at speeds to 80,000 rpm and radial loads to 440 n (100 lbf). The bearing assembly consisted of a pair of 20-mm angular-contact ball bearings encased in a journal, which was in turn supported by a fluid film of liquid hydrogen. The size and operating conditions of the bearing were selected to be compatible with the operating requirements of an advanced technology turbopump. Several test parameters were varied to characterize the bearing's steady-state operation. The rotation of the tester shaft was varied between 0 and 80,000 rpm. Bearing inlet fluid pressure was varied between 2.07 and 4.48 MPa (300 and 650 psia), while the fluid sump pressure was independently varied between 0.34 and 2.07 MPa (50 and 300 psia). The maximum radial load applied to the bearing was 440 N (110 lbf). Measured hybrid-hydrostatic-bearing stiffness was 1.5 times greater than predicted, while the fluid flow rate through the bearing was 35 to 65 percent less than predicted. Under two-phase fluid conditions, the stiffness was even greater and the flow rate was less. The optimal pressure ratio for the bearing should be between 0.2 and 0.55 depending on the balance desired between bearing efficiency and stiffness. Startup and shutdown cyclic tests were conducted to demonstrate the ability of the hybrid-hydrostatic-bearing assembly to survive at least a 300-firing-duty cycle. For a typical cycle, the shaft was accelerated to 50,000 rpm in 1.8 sec. The bearing operated for 337 start-stop cycles without failure.

  19. Two-layer Crustal Structure of the Contiguous United States from Joint Inversion of USArray Receiver Functions and Gravity

    NASA Astrophysics Data System (ADS)

    Ma, X.; Lowry, A. R.

    2015-12-01

    The composition and thickness of crustal layering is fundamental to understanding the evolution and dynamics of continental lithosphere. Lowry and Pérez-Gussinyé (2011) found that the western Cordillera of the United States, characterized by active deformation and high heat flow, is strongly correlated with low bulk crustal seismic velocity ratio. They interpreted this observation as evidence that quartz controls continental tectonism and deformation. We will present new imaging of two-layer crustal composition and structure from cross-correlation of observed receiver functions and model synthetics. The cross-correlation coefficient of the two-layer model increases significantly relative to an assumed one-layer model, and the lower crustal thickness map from raw two-layer modeling (prior to Bayesian filtering with gravity models and Optimal Interpolation) clearly shows Colorado plateau and Appalachian boundaries, which are not apparent in upper crustal models, and also the high vP/vS fill the most of middle continental region while low vP/vS are on the west and east continental edge. In the presentation, we will show results of a new algorithm for joint Bayesian inversion of thickness and vP/vS of two-layer continental crustal structure. Recent thermodynamical modeling of geophysical models based on lab experiment data (Guerri et al., 2015) found that a large impedance contrast can be expected in the midcrust due to a phase transition that decreases plagioclase and increases clinopyroxene, without invoking any change in crustal chemistry. The depth of the transition depends on pressure, temperature and hydration, and in this presentation we will compare predictions of layer thicknesses and vP/vS predicted by mineral thermodynamics to those we observe in the USArray footprint.

  20. The dynamic characteristics of hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Pang, Zhicheng; Sun, Jingwu; Zhai, Wenjie; Liu, Qingming; Chi, Wei

    1993-07-01

    Results of a theoretical study of the characteristics of hydrostatic bearings performed in terms of the compressibility of the air-contained oil are presented. A formula for the stability criterion of a hydrostatic bearing system and a dynamic stiffness formula is derived. It is found that, under the sinusoidal load, each of the pressure compensation systems has its own load frequency-film characteristics. The greater that compressible volume, V(oa), of oil, the smaller the dynamic stiffness. V(oa) must be reduced in the design of high-precision hydrostatic bearings. If the load frequency is in the low-stiffness area, the dynamic stiffness is small. Methods to enhance the dynamic stiffness are discussed.

  1. Spatial variability of steady-state infiltration into a two-layer soil system on burned hillslopes

    USGS Publications Warehouse

    Kinner, D.A.; Moody, J.A.

    2010-01-01

    Rainfall-runoff simulations were conducted to estimate the characteristics of the steady-state infiltration rate into 1-m2 north- and south-facing hillslope plots burned by a wildfire in October 2003. Soil profiles in the plots consisted of a two-layer system composed of an ash on top of sandy mineral soil. Multiple rainfall rates (18.4-51.2 mm h-1) were used during 14 short-duration (30 min) and 2 long-duration simulations (2-4 h). Steady state was reached in 7-26 min. Observed spatially-averaged steady-state infiltration rates ranged from 18.2 to 23.8 mm h-1 for north-facing and from 17.9 to 36.0 mm h-1 for south-facing plots. Three different theoretical spatial distribution models of steady-state infiltration rate were fit to the measurements of rainfall rate and steady-state discharge to provided estimates of the spatial average (19.2-22.2 mm h-1) and the coefficient of variation (0.11-0.40) of infiltration rates, overland flow contributing area (74-90% of the plot area), and infiltration threshold (19.0-26 mm h-1). Tensiometer measurements indicated a downward moving pressure wave and suggest that infiltration-excess overland flow is the runoff process on these burned hillslope with a two-layer system. Moreover, the results indicate that the ash layer is wettable, may restrict water flow into the underlying layer, and increase the infiltration threshold; whereas, the underlying mineral soil, though coarser, limits the infiltration rate. These results of the spatial variability of steady-state infiltration can be used to develop physically-based rainfall-runoff models for burned areas with a two-layer soil system. ?? 2010 Elsevier B.V.

  2. A high-order staggered finite-element vertical discretization for non-hydrostatic atmospheric models

    NASA Astrophysics Data System (ADS)

    Guerra, Jorge E.; Ullrich, Paul A.

    2016-06-01

    Atmospheric modeling systems require economical methods to solve the non-hydrostatic Euler equations. Two major differences between hydrostatic models and a full non-hydrostatic description lies in the vertical velocity tendency and numerical stiffness associated with sound waves. In this work we introduce a new arbitrary-order vertical discretization entitled the staggered nodal finite-element method (SNFEM). Our method uses a generalized discrete derivative that consistently combines the discontinuous Galerkin and spectral element methods on a staggered grid. Our combined method leverages the accurate wave propagation and conservation properties of spectral elements with staggered methods that eliminate stationary (2Δx) modes. Furthermore, high-order accuracy also eliminates the need for a reference state to maintain hydrostatic balance. In this work we demonstrate the use of high vertical order as a means of improving simulation quality at relatively coarse resolution. We choose a test case suite that spans the range of atmospheric flows from predominantly hydrostatic to nonlinear in the large-eddy regime. Our results show that there is a distinct benefit in using the high-order vertical coordinate at low resolutions with the same robust properties as the low-order alternative.

  3. A high-order staggered finite-element vertical discretization for non-hydrostatic atmospheric models

    DOE PAGES

    Guerra, Jorge E.; Ullrich, Paul A.

    2016-06-01

    Atmospheric modeling systems require economical methods to solve the non-hydrostatic Euler equations. Two major differences between hydrostatic models and a full non-hydrostatic description lies in the vertical velocity tendency and numerical stiffness associated with sound waves. In this work we introduce a new arbitrary-order vertical discretization entitled the staggered nodal finite-element method (SNFEM). Our method uses a generalized discrete derivative that consistently combines the discontinuous Galerkin and spectral element methods on a staggered grid. Our combined method leverages the accurate wave propagation and conservation properties of spectral elements with staggered methods that eliminate stationary (2Δx) modes. Furthermore, high-order accuracy alsomore » eliminates the need for a reference state to maintain hydrostatic balance. In this work we demonstrate the use of high vertical order as a means of improving simulation quality at relatively coarse resolution. We choose a test case suite that spans the range of atmospheric flows from predominantly hydrostatic to nonlinear in the large-eddy regime. Our results show that there is a distinct benefit in using the high-order vertical coordinate at low resolutions with the same robust properties as the low-order alternative.« less

  4. On variable hydrostatic transmission for road vehicles, powered by supply of fluid at constant pressure

    NASA Technical Reports Server (NTRS)

    Magi, M.; Freivald, A.; Andersson, I.; Ericsson, U.

    1981-01-01

    Various hydrostatic power transmission systems for automotive applications with power supply at constant pressure and unrestricted flow and with a Volvo Flygmotor variable displacement motor as the principal unit were investigated. Two most promising concepts were analyzed in detail and their main components optimized for minimum power loss at the EPA Urban Driving Cycle. The best fuel consumption is less than 10 lit. per 100 kM for a 1542 kG vehicle with a hydrostatic motor and a two speed gear box in series (braking power not recovered). Realistic system pressure affects the fuel consumption just slightly, but the package volume/weight drastically. Back pressure increases losses significantly. Special attention was paid to description of the behavior and modeling of the losses of variable displacement hydrostatic machines.

  5. On variable hydrostatic transmission for road vehicles, powered by supply of fluid at constant pressure

    SciTech Connect

    Magi, M.; Freivald, A.; Anderson, I.

    1981-05-01

    Various hydrostatic power transmission systems for automotive applications with power supply at constant pressure and unrestricted flow and with a Volvo Flygmotor variable displacement motor as the principal unit were investigated. Two most promising concepts were analyzed in detail and their main components optimized for minimum power loss at the EPA Urban Driving Cycle. The best fuel consumption is less than 10 lit. per 100 kM for a 1542 kG vehicle with a hydrostatic motor and a two speed gear box in series (braking power not recovered). Realistic system pressure affects the fuel consumption just slightly, but the package volume/weight drastically. Back pressure increases losses significantly. Special attention was paid to description of the behavior and modeling of the losses of variable displacement hydrostatic machines.

  6. Research on carrying capacity of hydrostatic slideway on heavy-duty gantry CNC machine

    NASA Astrophysics Data System (ADS)

    Cui, Chao; Guo, Tieneng; Wang, Yijie; Dai, Qin

    2017-05-01

    Hydrostatic slideway is a key part in the heavy-duty gantry CNC machine, which supports the total weight of the gantry and moves smoothly along the table. Therefore, the oil film between sliding rails plays an important role on the carrying capacity and precision of machine. In this paper, the oil film in no friction is simulated with three-dimensional CFD. The carrying capacity of heavy hydrostatic slideway, pressure and velocity characteristic of the flow field are analyzed. The simulation result is verified through comparing with the experimental data obtained from the heavy-duty gantry machine. For the requirement of engineering, the oil film carrying capacity is analyzed with simplified theoretical method. The precision of the simplified method is evaluated and the effectiveness is verified with the experimental data. The simplified calculation method is provided for designing oil pad on heavy-duty gantry CNC machine hydrostatic slideway.

  7. Geostrophic tripolar vortices in a two-layer fluid: Linear stability and nonlinear evolution of equilibria

    NASA Astrophysics Data System (ADS)

    Reinaud, J. N.; Sokolovskiy, M. A.; Carton, X.

    2017-03-01

    We investigate equilibrium solutions for tripolar vortices in a two-layer quasi-geostrophic flow. Two of the vortices are like-signed and lie in one layer. An opposite-signed vortex lies in the other layer. The families of equilibria can be spanned by the distance (called separation) between the two like-signed vortices. Two equilibrium configurations are possible when the opposite-signed vortex lies between the two other vortices. In the first configuration (called ordinary roundabout), the opposite signed vortex is equidistant to the two other vortices. In the second configuration (eccentric roundabouts), the distances are unequal. We determine the equilibria numerically and describe their characteristics for various internal deformation radii. The two branches of equilibria can co-exist and intersect for small deformation radii. Then, the eccentric roundabouts are stable while unstable ordinary roundabouts can be found. Indeed, ordinary roundabouts exist at smaller separations than eccentric roundabouts do, thus inducing stronger vortex interactions. However, for larger deformation radii, eccentric roundabouts can also be unstable. Then, the two branches of equilibria do not cross. The branch of eccentric roundabouts only exists for large separations. Near the end of the branch of eccentric roundabouts (at the smallest separation), one of the like-signed vortices exhibits a sharp inner corner where instabilities can be triggered. Finally, we investigate the nonlinear evolution of a few selected cases of tripoles.

  8. Two-layer convective heating prediction procedures and sensitivities for blunt body reentry vehicles

    NASA Technical Reports Server (NTRS)

    Bouslog, Stanley A.; An, Michael Y.; Wang, K. C.; Tam, Luen T.; Caram, Jose M.

    1993-01-01

    This paper provides a description of procedures typically used to predict convective heating rates to hypersonic reentry vehicles using the two-layer method. These procedures were used to compute the pitch-plane heating distributions to the Apollo geometry for a wind tunnel test case and for three flight cases. Both simple engineering methods and coupled inviscid/boundary layer solutions were used to predict the heating rates. The sensitivity of the heating results in the choice of metrics, pressure distributions, boundary layer edge conditions, and wall catalycity used in the heating analysis were evaluated. Streamline metrics, pressure distributions, and boundary layer edge properties were defined from perfect gas (wind tunnel case) and chemical equilibrium and nonequilibrium (flight cases) inviscid flow-field solutions. The results of this study indicated that the use of CFD-derived metrics and pressures provided better predictions of heating when compared to wind tunnel test data. The study also showed that modeling entropy layer swallowing and ionization had little effect on the heating predictions.

  9. Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

    SciTech Connect

    Xiao, Jianwei; Du, Jinglian; Wen, Bin Zhang, Xiangyi; Melnik, Roderick; Kawazoe, Yoshiyuki

    2014-04-28

    Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ∼1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

  10. Numerical Simulation of Damage during Forging with Superimposed Hydrostatic Pressure by Active Media

    SciTech Connect

    Behrens, B.-A.; Hagen, T.; Roehr, S.; Sidhu, K. B.

    2007-05-17

    The effective reduction of energy consumption and a reasonable treatment of resources can be achieved by minimizing a component's weight using lightweight metals. In this context, aluminum alloys play a major role. Due to their material-sided restricted formability, the mentioned aluminum materials are difficult to form. The plasticity of a material is ascertained by its maximum forming limit. It is attained, when the deformation causes mechanical damage within the material. Damage of that sort is reached more rapidly, the greater the tensile strength rate in relation to total tension rate. A promising approach of handling these low ductile, high-strength aluminum alloys within a forming process, is forming with a synchronized superposition of comprehensive stress by active media such as by controlling oil pressure. The influence of superimposed hydrostatic pressure on the flow stress was analyzed as well as the formability for different procedures at different hydrostatic pressures and temperature levels. It was observed that flow stress is independent of superimposed hydrostatic pressure. Neither the superimposed pressure has an influence on the plastic deformation, nor does a pressure dependent material hardening due to increasing hydrostatic pressure take place. The formability increases with rising hydrostatic pressure. The relative gain at room temperature and increase of the superimposed pressure from 0 to 600 bar for tested materials was at least 140 % and max. 220 %. Therefore in this paper, based on these experimental observations, it is the intended to develop a numerical simulation in order to predict ductile damage that occurs in the bulk forging process with superimposed hydrostatic pressure based Lemaitre's damage model.

  11. Numerical Simulation of Damage during Forging with Superimposed Hydrostatic Pressure by Active Media

    NASA Astrophysics Data System (ADS)

    Behrens, B.-A.; Hagen, T.; Röhr, S.; Sidhu, K. B.

    2007-05-01

    The effective reduction of energy consumption and a reasonable treatment of resources can be achieved by minimizing a component's weight using lightweight metals. In this context, aluminum alloys play a major role. Due to their material-sided restricted formability, the mentioned aluminum materials are difficult to form. The plasticity of a material is ascertained by its maximum forming limit. It is attained, when the deformation causes mechanical damage within the material. Damage of that sort is reached more rapidly, the greater the tensile strength rate in relation to total tension rate. A promising approach of handling these low ductile, high-strength aluminum alloys within a forming process, is forming with a synchronized superposition of comprehensive stress by active media such as by controlling oil pressure. The influence of superimposed hydrostatic pressure on the flow stress was analyzed as well as the formability for different procedures at different hydrostatic pressures and temperature levels. It was observed that flow stress is independent of superimposed hydrostatic pressure. Neither the superimposed pressure has an influence on the plastic deformation, nor does a pressure dependent material hardening due to increasing hydrostatic pressure take place. The formability increases with rising hydrostatic pressure. The relative gain at room temperature and increase of the superimposed pressure from 0 to 600 bar for tested materials was at least 140 % and max. 220 %. Therefore in this paper, based on these experimental observations, it is the intended to develop a numerical simulation in order to predict ductile damage that occurs in the bulk forging process with superimposed hydrostatic pressure based Lemaitre's damage model.

  12. Effect of different downstream temperatures on the performance of a two-layer porous burner

    NASA Astrophysics Data System (ADS)

    Hayashi, T. C.; Malico, I.; Pereira, J. C. F.

    2010-07-01

    The influence of considering different downstream temperatures on the performance of a two-layer porous burner is studied numerically. A 3D numerical model based on a unit cell was implemented to correctly predict the momentum, heat and mass transfer at the interface of the two layers. Two operating modes are simulated corresponding to the burner radiating to cold and hot environments. When the burner radiates to a hot environment, its radiative heat losses are lower and, as a consequence, the temperatures and pollutants emissions are higher. Additionally, the flame front moves upstream and stabilizes nearer the interface of the two layers.

  13. Physiological damages of Listeria monocytogenes treated by high hydrostatic pressure.

    PubMed

    Ritz, M; Tholozan, J L; Federighi, M; Pilet, M F

    2002-11-15

    High hydrostatic pressure is a new food preservation technology known for its capacity to inactivate spoilage and pathogenic microorganisms. This study investigated the damages inflicted on Listeria monocytogenes cells treated by high pressure for 10 min at 400 MPa in pH 5.6 citrate buffer. Under these conditions, no cell growth occurred after 48 h on plate count agar. Scanning electron microscopy (SEM) revealed that cellular morphology was not really affected. Measuring propidium iodide (PI) staining followed by flow cytometry demonstrated that membrane integrity was damaged in a small part of the population, although the membrane potential evaluated by oxonol fluorescence or measured by analytical methods was reduced from - 86 to - 5 mV. These results for the first time showed that such combined methods as fluorescent dyes monitored by flow cytometry and physiological activity measurements provide valuable indications on cellular viability.

  14. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... INSPECTIONS Tests and Inspections of Fired Thermal Fluid Heaters § 61.30-10 Hydrostatic test. All new installations of thermal fluid heaters must be given a hydrostatic test of 11/2 times the maximum allowable... condition of the heater warrants such a test. Where hydrostatic tests are required, an inspection is made...

  15. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... INSPECTIONS Tests and Inspections of Fired Thermal Fluid Heaters § 61.30-10 Hydrostatic test. All new installations of thermal fluid heaters must be given a hydrostatic test of 11/2 times the maximum allowable... all accessible parts under pressure. The thermal fluid may be used as the hydrostatic test medium. ...

  16. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... INSPECTIONS Tests and Inspections of Fired Thermal Fluid Heaters § 61.30-10 Hydrostatic test. All new installations of thermal fluid heaters must be given a hydrostatic test of 11/2 times the maximum allowable... all accessible parts under pressure. The thermal fluid may be used as the hydrostatic test medium. ...

  17. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Hydrostatic pressure test. 178.814 Section 178.814... Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the qualification... loaded or discharged under pressure or intended to contain liquids. (b) Special preparation for...

  18. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Hydrostatic pressure test. 178.814 Section 178.814... Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the qualification... loaded or discharged under pressure or intended to contain liquids. (b) Special preparation for...

  19. 49 CFR 178.605 - Hydrostatic pressure test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Hydrostatic pressure test. 178.605 Section 178.605... Packagings and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must... required for inner packagings of combination packagings. For internal pressure requirements for...

  20. 49 CFR 178.605 - Hydrostatic pressure test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrostatic pressure test. 178.605 Section 178.605... Testing of Non-bulk Packagings and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the qualification of all metal, plastic, and...

  1. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Hydrostatic pressure test. 178.814 Section 178.814... Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the qualification... loaded or discharged under pressure or intended to contain liquids. (b) Special preparation for...

  2. 49 CFR 178.605 - Hydrostatic pressure test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Hydrostatic pressure test. 178.605 Section 178.605... Packagings and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must... required for inner packagings of combination packagings. For internal pressure requirements for...

  3. 49 CFR 178.605 - Hydrostatic pressure test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Hydrostatic pressure test. 178.605 Section 178.605... Packagings and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must... required for inner packagings of combination packagings. For internal pressure requirements for...

  4. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Hydrostatic pressure test. 178.814 Section 178.814... Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be conducted for the qualification... loaded or discharged under pressure or intended to contain liquids. (b) Special preparation for...

  5. 49 CFR 178.814 - Hydrostatic pressure test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrostatic pressure test. 178.814 Section 178.814... Testing of IBCs § 178.814 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must be... contain solids that are loaded or discharged under pressure or intended to contain liquids. (b)...

  6. 49 CFR 178.605 - Hydrostatic pressure test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Hydrostatic pressure test. 178.605 Section 178.605... Packagings and Packages § 178.605 Hydrostatic pressure test. (a) General. The hydrostatic pressure test must... required for inner packagings of combination packagings. For internal pressure requirements for...

  7. A Load Cell for Hydrostatic Weighing

    ERIC Educational Resources Information Center

    Fahey, Thomas D.; Schroeder, Richard

    1978-01-01

    Although a load cell is more expensive than the autopsy scale for hydrostatic weighing, it is more accurate, easier to read, has no moving parts, is less susceptible to rust, and is less likely to be damaged by large subjects exceeding its capacity. (Author)

  8. Railcar waste transfer system hydrostatic test

    SciTech Connect

    Ellingson, S.D.

    1997-03-31

    Recent modifications have been performed on the T-Plant Railcar Waste Transfer System, This Acceptance Test Procedure (ATP) has been prepared to demonstrate that identified piping welds and mechanical connections incorporated during the modification are of high integrity and are acceptable for service. This will be achieved by implementation of a hydrostatic leak test.

  9. Railcar waste transfer system hydrostatic test report

    SciTech Connect

    Ellingson, S.D.

    1997-04-03

    This Acceptance Test Report (ATR) documents for record purposes the field results, acceptance, and approvals of the completed acceptance test per HNF-SD-W417-ATP-001, ''Rail car Waste Transfer System Hydrostatic Test''. The test was completed and approved without any problems or exceptions.

  10. Modifications Of Hydrostatic-Bearing Computer Program

    NASA Technical Reports Server (NTRS)

    Hibbs, Robert I., Jr.; Beatty, Robert F.

    1991-01-01

    Several modifications made to enhance utility of HBEAR, computer program for analysis and design of hydrostatic bearings. Modifications make program applicable to more realistic cases and reduce time and effort necessary to arrive at a suitable design. Uses search technique to iterate on size of orifice to obtain required pressure ratio.

  11. A Load Cell for Hydrostatic Weighing

    ERIC Educational Resources Information Center

    Fahey, Thomas D.; Schroeder, Richard

    1978-01-01

    Although a load cell is more expensive than the autopsy scale for hydrostatic weighing, it is more accurate, easier to read, has no moving parts, is less susceptible to rust, and is less likely to be damaged by large subjects exceeding its capacity. (Author)

  12. Characteristics of a two-layer electromagnetically coupled rectangular patch antenna

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Lee, K. F.; Bobinchak, J.

    1987-01-01

    Experimental results on the characteristics of a two-layer electromagnetically coupled rectangular patch antenna are presented. The variations of pattern shape, 3 dB beam width, and impedance bandwidth with spacing s between the two layers are studied for s between 0 and 0.37 lambda (0). A relatively high-gain region is found for s between 0.31 lambda (0) and 0.37 lambda (0).

  13. Experimental study of the two-layer electromagnetically coupled rectangular patch antenna

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Lee, Kai-Fong

    1990-01-01

    Experimental results on the characteristics of two-layer electromagnetically coupled rectangular patch antennas are presented. In addition to the relatively large bandwidth region that occurs when the separation between the two layers is less than 0.15 wavelength, a high-gain region is found when the separation exceeds 0.3 wavelength. The relative sizes of the parasitic and fed patches are found to have significant effects on the resonant input resistance and bandwidth.

  14. Strength Differential Measured in Inconel 718: Effects of Hydrostatic Pressure Studied

    NASA Technical Reports Server (NTRS)

    Lewandowski, John J.; Wesseling, Paul; Prabhu, Nishad S.; Larose, Joel; Lissenden, Cliff J.; Lerch, Bradley A.

    2003-01-01

    Aeropropulsion components, such as disks, blades, and shafts, are commonly subjected to multiaxial stress states at elevated temperatures. Experimental results from loadings as complex as those experienced in service are needed to help guide the development of accurate viscoplastic, multiaxial deformation models that can be used to improve the design of these components. During a recent study on multiaxial deformation (ref. 1) on a common aerospace material, Inconel 718, it was shown that the material in the aged state exhibits a strength differential effect (SDE), whereby the uniaxial compressive yield and subsequent flow behavior are significantly higher than those in uniaxial tension. Thus, this material cannot be described by a standard von Mises yield formulation. There have been other formulations postulated (ref. 2) that involve other combinations of the stress invariants, including the effect of hydrostatic stress. The question remained as to which invariants are necessary in the flow model. To capture the physical mechanisms occurring during deformation and reflect them in the plasticity formulation, researchers examined the flow of Inconel 718 under various amounts of hydrostatic stress to determine whether or not hydrostatic stress is needed in the formulation. Under NASA Grant NCC3-464, monitored by the NASA Glenn Research Center, a series of tensile tests were conducted at Case Western Reserve University on aged (precipitation hardened) Inconel 718 at 650 C and with superimposed hydrostatic pressure. Dogbone shaped tensile specimens (3-mm-diameter gauge by 16-mm gauge length) and cylindrical compression specimens (3-mm-diameter gauge by 6-mm gauge length) were strain gauged and loaded in a high-pressure testing apparatus. Hydrostatic pressures were obtained with argon and ranged from 210 to 630 MPa. The aged Inconel 718 showed a pronounced difference in the tension and compression yield strength (i.e., an SDE), as previously observed. Also, there were

  15. Convective instability in a two-layer system of reacting fluids with concentration-dependent diffusion

    NASA Astrophysics Data System (ADS)

    Aitova, E. V.; Bratsun, D. A.; Kostarev, K. G.; Mizev, A. I.; Mosheva, E. A.

    2016-12-01

    The development of convective instability in a two-layer system of miscible fluids placed in a narrow vertical gap has been studied theoretically and experimentally. The upper and lower layers are formed with aqueous solutions of acid and base, respectively. When the layers are brought into contact, the frontal neutralization reaction begins. We have found experimentally a new type of convective instability, which is characterized by the spatial localization and the periodicity of the structure observed for the first time in the miscible systems. We have tested a number of different acid-base systems and have found a similar patterning there. In our opinion, it may indicate that the discovered effect is of a general nature and should be taken into account in reaction-diffusion-convection problems as another tool with which the reaction can govern the movement of the reacting fluids. We have shown that, at least in one case (aqueous solutions of nitric acid and sodium hydroxide), a new type of instability called as the concentration-dependent diffusion convection is responsible for the onset of the fluid flow. It arises when the diffusion coefficients of species are different and depend on their concentrations. This type of instability can be attributed to a variety of double-diffusion convection. A mathematical model of the new phenomenon has been developed using the system of reaction-diffusion-convection equations written in the Hele-Shaw approximation. It is shown that the instability can be reproduced in the numerical experiment if only one takes into account the concentration dependence of the diffusion coefficients of the reagents. The dynamics of the base state, its linear stability and nonlinear development of the instability are presented. It is also shown that by varying the concentration of acid in the upper layer one can achieve the occurrence of chemo-convective solitary cell in the bulk of an almost immobile fluid. Good agreement between the

  16. Hydrostatic Pressure Independently Increases Elastin and Collagen Co-expression in Small-diameter Engineered Arterial Constructs

    PubMed Central

    Crapo, Peter M.; Wang, Yadong

    2011-01-01

    Prior studies have demonstrated that smooth muscle cell (SMC) proliferation, migration, and extracellular matrix production increase with hydrostatic pressure in vitro. We have engineered highly compliant small-diameter arterial constructs by culturing primary adult arterial SMCs under pulsatile perfusion on tubular, porous, elastomeric scaffolds composed of poly(glycerol sebacate) (PGS). This study investigates the effect of hydrostatic pressure on the biological and mechanical properties of PGS-based engineered arterial constructs. Pressure was raised using a downstream needle valve during perfusion while preserving flow rate and pulsatility, and constructs were evaluated by pressure-diameter testing and biochemical assays for collagen and elastin. Pressurized constructs contained half as much insoluble elastin as baboon common carotid arteries but were significantly less compliant, while constructs cultured at low hydrostatic pressure contained one third as much insoluble elastin as baboon carotids and were similar in compliance. Hydrostatic pressure significantly increased construct burst pressure, collagen and insoluble elastin content, and soluble elastin concentration in culture medium. All arteries and constructs exhibited elastic recovery during pressure cycling. Hydrostatic pressure did not appear to affect radial distribution of SMCs, collagens I and III, and elastin. These results provide insights into the control of engineered smooth muscle tissue properties using hydrostatic pressure. PMID:21268239

  17. Low hydrostatic head electrolyte addition to fuel cell stacks

    DOEpatents

    Kothmann, Richard E.

    1983-01-01

    A fuel cell and system for supply electrolyte, as well as fuel and an oxidant to a fuel cell stack having at least two fuel cells, each of the cells having a pair of spaced electrodes and a matrix sandwiched therebetween, fuel and oxidant paths associated with a bipolar plate separating each pair of adjacent fuel cells and an electrolyte fill path for adding electrolyte to the cells and wetting said matrices. Electrolyte is flowed through the fuel cell stack in a back and forth fashion in a path in each cell substantially parallel to one face of opposite faces of the bipolar plate exposed to one of the electrodes and the matrices to produce an overall head uniformly between cells due to frictional pressure drop in the path for each cell free of a large hydrostatic head to thereby avoid flooding of the electrodes. The bipolar plate is provided with channels forming paths for the flow of the fuel and oxidant on opposite faces thereof, and the fuel and the oxidant are flowed along a first side of the bipolar plate and a second side of the bipolar plate through channels formed into the opposite faces of the bipolar plate, the fuel flowing through channels formed into one of the opposite faces and the oxidant flowing through channels formed into the other of the opposite faces.

  18. A Multipurpose Device for Some Hydrostatics Questions

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2008-01-01

    A number of well-known hydrostatics problems dealing with Archimedes' principle concern a loaded boat floating in a pool. Examples of this sort of problem include: 1. (a) If a stone is thrown overboard from a boat floating in a pool, does the water level in the pool rise, fall, or remain unchanged? (b) If a hole is made in the bottom of the boat…

  19. A Multipurpose Device for Some Hydrostatics Questions

    ERIC Educational Resources Information Center

    Ganci, Salvatore

    2008-01-01

    A number of well-known hydrostatics problems dealing with Archimedes' principle concern a loaded boat floating in a pool. Examples of this sort of problem include: 1. (a) If a stone is thrown overboard from a boat floating in a pool, does the water level in the pool rise, fall, or remain unchanged? (b) If a hole is made in the bottom of the boat…

  20. Role of osmotic and hydrostatic pressures in bacteriophage genome ejection

    NASA Astrophysics Data System (ADS)

    Lemay, Serge G.; Panja, Debabrata; Molineux, Ian J.

    2013-02-01

    A critical step in the bacteriophage life cycle is genome ejection into host bacteria. The ejection process for double-stranded DNA phages has been studied thoroughly in vitro, where after triggering with the cellular receptor the genome ejects into a buffer. The experimental data have been interpreted in terms of the decrease in free energy of the densely packed DNA associated with genome ejection. Here we detail a simple model of genome ejection in terms of the hydrostatic and osmotic pressures inside the phage, a bacterium, and a buffer solution or culture medium. We argue that the hydrodynamic flow associated with the water movement from the buffer solution into the phage capsid and further drainage into the bacterial cytoplasm, driven by the osmotic gradient between the bacterial cytoplasm and culture medium, provides an alternative mechanism for phage genome ejection in vivo; the mechanism is perfectly consistent with phage genome ejection in vitro.

  1. A two-layer multiple-time-scale turbulence model and grid independence study

    NASA Technical Reports Server (NTRS)

    Kim, S.-W.; Chen, C.-P.

    1989-01-01

    A two-layer multiple-time-scale turbulence model is presented. The near-wall model is based on the classical Kolmogorov-Prandtl turbulence hypothesis and the semi-empirical logarithmic law of the wall. In the two-layer model presented, the computational domain of the conservation of mass equation and the mean momentum equation penetrated up to the wall, where no slip boundary condition has been prescribed; and the near wall boundary of the turbulence equations has been located at the fully turbulent region, yet very close to the wall, where the standard wall function method has been applied. Thus, the conservation of mass constraint can be satisfied more rigorously in the two-layer model than in the standard wall function method. In most of the two-layer turbulence models, the number of grid points to be used inside the near-wall layer posed the issue of computational efficiency. The present finite element computational results showed that the grid independent solutions were obtained with as small as two grid points, i.e., one quadratic element, inside the near wall layer. Comparison of the computational results obtained by using the two-layer model and those obtained by using the wall function method is also presented.

  2. Characterization of a two-layer aquifer using well drawdown data

    NASA Astrophysics Data System (ADS)

    Vanclooster, M.; Frippiat, C. C.; Holeyman, A.; Peeters, G.

    2009-12-01

    Well drawdown data are usually exploited as an indicator of aquifer and well performance. When expressed under the form of specific capacity, defined as well production per unit decline in head, it is also quite widely used to estimate aquifer transmissivity, mainly from empirical relationships. Analytical models have also been used to relate specific capacity to transmissivity, but additional corrections (e.g. for nonlinear head losses) have to be accounted for. In this paper, we explore the possibility of using well drawdown data to characterize a two-layer unconfined aquifer. The test site is located in Louvain-la-Neuve, Belgium. The aquifer consists of a deep layer of less conductive Landenian sand and a shallower layer of more conductive Brusselean sand, in which the water table is located. Drawdown data obtained in a pumping well fully penetrating both layers down to the bedrock exhibited a very atypical behavior. At low pumping rates, specific capacity remained relatively constant. At a certain threshold pumping rate, drawdown started to increase drastically. While such a behavior could be attributed to the unconfined nature of the aquifer, or to laminar and turbulent head losses near the well, we show that it is mainly a consequence of the dewatering of the upper, more conductive layer of the aquifer. The approach adopted in this study required the development of a detailed numerical model of saturated flow towards the well using the code FEHM (Finite Element Heat and Mass transport code, developed at Los Alamos National Laboratory). The well was represented as cells with unit porosity and high permeability. The model was automatically inverted using UCODE 2005 in order to estimate permeabilities of both layers and the position of their interface from steady-state well drawdown data collected for various pumping rates. The estimated value of permeability of the lower, less conductive layer was also compared to results from slug tests performed in near

  3. No confinement needed: observation of a metastable hydrophobic wetting two-layer ice on graphene.

    PubMed

    Kimmel, Greg A; Matthiesen, Jesper; Baer, Marcel; Mundy, Christopher J; Petrik, Nikolay G; Smith, R Scott; Dohnálek, Zdenek; Kay, Bruce D

    2009-09-09

    The structure of water at interfaces is crucial for processes ranging from photocatalysis to protein folding. Here, we investigate the structure and lattice dynamics of two-layer crystalline ice films grown on a hydrophobic substrate, graphene on Pt(111), with low energy electron diffraction, reflection-absorption infrared spectroscopy, rare-gas adsorption/desorption, and ab initio molecular dynamics. Unlike hexagonal ice, which consists of stacks of puckered hexagonal "bilayers", this new ice polymorph consists of two flat hexagonal sheets of water molecules in which the hexagons in each sheet are stacked directly on top of each other. Such two-layer ices have been predicted for water confined between hydrophobic walls, but not previously observed experimentally. Our results show that the two-layer ice forms even at zero pressure at a single hydrophobic interface by maximizing the number of hydrogen bonds at the expense of adopting a nontetrahedral geometry with weakened hydrogen bonds.

  4. No Confinement Needed: Observation of a Metastable Hydrophobic Wetting Two-Layer Ice on Graphene

    SciTech Connect

    Kimmel, Gregory A.; Matthiesen, Jesper; Baer, Marcel; Mundy, Christopher J.; Petrik, Nikolay G.; Smith, R. Scott; Dohnalek, Zdenek; Kay, Bruce D.

    2009-09-09

    The structure of water at interfaces is crucial for processes ranging from photocatalysis to protein folding. Here, we investigate the structure and lattice dynamics of two-layer crystalline ice films grown on a hydrophobic substrate - graphene on Pt(111) - with low energy electron diffraction, reflection-absorption infrared spectroscopy, rare-gas adsorption/desorption, and ab-initio molecular dynamics. Unlike hexagonal ice, which consists of stacks of puckered hexagonal "bilayers", this new ice polymorph consists of two flat hexagonal sheets of water molecules in which the hexagons in each sheet are stacked directly on top of each other. Such two-layer ices have been predicted for water confined between hydrophobic slits, but not previously observed. Our results show that the two-layer ice forms even at zero pressure at a single hydrophobic interface by maximizing the number of hydrogen bonds at the expense of adopting a non-tetrahedral geometry with weakened bonds.

  5. Enhancing robustness of interdependent network under recovery based on a two-layer-protection strategy.

    PubMed

    Gong, Maoguo; Wang, Yixing; Wang, Shanfeng; Liu, Wenfeng

    2017-10-06

    The robustness of coupled networks has attracted great attention recently, because the spread of failures from one network to its coupled network makes the coupled networks more vulnerable. Most existing achievements mainly focused on the integrity properties of coupled networks. However, failures also exist when networks are being reconstructed. Moreover, existing node-protection methods which aim to enhance the robustness of coupled networks only protect the influential nodes in one layer. In this paper, firstly, a two-layer-protection strategy is proposed to enhance the robustness of coupled networks under their reconstruction. Secondly, we adopt five strategies based on different centralities to select influential nodes, and propose a two-layer vision for each of them. Lastly, experiments on three different coupled networks show that by applying the two-layer-protection strategy, the robustness of coupled networks can be enhanced more efficiently compared with other methods which only protect nodes in one layer.

  6. Lie symmetry analysis and exact solutions of the quasigeostrophic two-layer problem

    NASA Astrophysics Data System (ADS)

    Bihlo, Alexander; Popovych, Roman O.

    2011-03-01

    The quasigeostrophic two-layer model is of superior interest in dynamic meteorology since it is one of the easiest ways to study baroclinic processes in geophysical fluid dynamics. The complete set of point symmetries of the two-layer equations is determined. An optimal set of one- and two-dimensional inequivalent subalgebras of the maximal Lie invariance algebra is constructed. On the basis of these subalgebras, we exhaustively carry out group-invariant reduction and compute various classes of exact solutions. Wherever possible, reference to the physical meaning of the exact solutions is given. In particular, the well-known baroclinic Rossby wave solutions in the two-layer model are rediscovered.

  7. A two-layer approach to the coupled coherent states method

    SciTech Connect

    Green, James A. Ronto, Miklos Shalashilin, Dmitrii V.; Grigolo, Adriano

    2016-01-14

    In this paper, a two-layer scheme is outlined for the coupled coherent states (CCS) method, dubbed two-layer CCS (2L-CCS). The theoretical framework is motivated by that of the multiconfigurational Ehrenfest method, where different dynamical descriptions are used for different subsystems of a quantum mechanical system. This leads to a flexible representation of the wavefunction, making the method particularly suited to the study of composite systems. It was tested on a 20-dimensional asymmetric system-bath tunnelling problem, with results compared to a benchmark calculation, as well as existing CCS, matching-pursuit/split-operator Fourier transform, and configuration interaction expansion methods. The two-layer method was found to lead to improved short and long term propagation over standard CCS, alongside improved numerical efficiency and parallel scalability. These promising results provide impetus for future development of the method for on-the-fly direct dynamics calculations.

  8. Ultralong photonic nanojet formed by a two-layer dielectric microsphere.

    PubMed

    Shen, Yuecheng; Wang, Lihong V; Shen, Jung-Tsung

    2014-07-15

    A photonic nanojet is a highly focused optical beam with a subwavelength waist on the shadow side of the sphere. Successful far-field applications require long nanojets that extend afar. Using the exact Mie theory, we show that ultralong nanojets can be generated using a simple two-layer microsphere structure, using conventional optical materials that are readily available. In particular, we show that for a glass-based two-layer microsphere, the nanojet has an extension of 22 wavelengths. We also show that long nanojets can be formed using semiconductors at infrared frequencies in free space.

  9. Thermal fluid-solid interaction model and experimental validation for hydrostatic mechanical face seals

    NASA Astrophysics Data System (ADS)

    Huang, Weifeng; Liao, Chuanjun; Liu, Xiangfeng; Suo, Shuangfu; Liu, Ying; Wang, Yuming

    2014-09-01

    Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants. More accurate models on the operating mechanism of the seals are needed to help improve their performance. The thermal fluid-solid interaction (TFSI) mechanism of the hydrostatic seal is investigated in this study. Numerical models of the flow field and seal assembly are developed. Based on the mechanism for the continuity condition of the physical quantities at the fluid-solid interface, an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method. Dynamic mesh technology is adopted to adapt to the changing boundary shape. Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure. The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data. Using the TFSI model, the behavior of the seal is presented, including mechanical and thermal deformation, and the temperature field. The influences of the rotating speed and differential pressure of the sealing device on the temperature field, which occur widely in the actual use of the seal, are studied. This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals, and the model is validated by full-sized experiments.

  10. Experimental equipment for measuring physical properties of the annular hydrostatic thrust bearing

    NASA Astrophysics Data System (ADS)

    Kozdera, Michal; Drábková, Sylva; Bojko, Marian

    2014-03-01

    The hydraulic circuit, through which the mineral oil is brought, is an important part of hydrostatic bearings. The annular hydrostatic thrust bearing consists of two sliding plates divided by a layer of mineral oil. In the lower plate, there are oil grooves which distribute the liquid between the sliding areas. The hydraulic circuit is made of two basic parts: the energy source and the controlling part. The hydraulic pump, which brings the liquid into the sliding bearing, is the source of the pressure energy. The sliding bearing is weighted down by axial force, which can be changed during the process. That's why in front of the particular oil grooves control components adjusting pressure and flow size are located. This paper deals with a project of a hydraulic circuit for regulation of fluid layer in the annular hydrostatic thrust bearing and the testing equipment for measuring its physical properties. It will include the issue of measuring loading capacity and height of the fluid layer in the annular hydrostatic thrust bearing.

  11. Experimental and numerical investigation of heat transfer for two-layered microchannel heat sink with non-uniform heat flux conditions

    NASA Astrophysics Data System (ADS)

    Xu, Shanglong; Yang, Lili; Li, Yue; Wu, Yihao; Hu, Xinglong

    2016-09-01

    To meet the cooling demand of electronic devices with multiple heat sources, we design two novel two-layer mini-channel heat sinks (3-port structure and 5-port structure) to improve the uniformity of surface temperature distribution. The temperature distribution and fluid flow in the two channel networks with single and two layer structures are investigated. The 5-port mini-channel network is verified to have a lower pressure drop and a better thermal performance compared with the 3-port one in terms of total thermal resistance and surface temperature distribution. For the 5-port 2-layer structure, the local thermal resistance ranges from 0.2 to 0.08 K/W at the flow rate of 400-900 ml/min while the pressure drop is lower than 2.5 kPa.

  12. Lens intracellular hydrostatic pressure is generated by the circulation of sodium and modulated by gap junction coupling

    PubMed Central

    Gao, Junyuan; Sun, Xiurong; Moore, Leon C.; White, Thomas W.; Brink, Peter R.

    2011-01-01

    We recently modeled fluid flow through gap junction channels coupling the pigmented and nonpigmented layers of the ciliary body. The model suggested the channels could transport the secretion of aqueous humor, but flow would be driven by hydrostatic pressure rather than osmosis. The pressure required to drive fluid through a single layer of gap junctions might be just a few mmHg and difficult to measure. In the lens, however, there is a circulation of Na+ that may be coupled to intracellular fluid flow. Based on this hypothesis, the fluid would cross hundreds of layers of gap junctions, and this might require a large hydrostatic gradient. Therefore, we measured hydrostatic pressure as a function of distance from the center of the lens using an intracellular microelectrode-based pressure-sensing system. In wild-type mouse lenses, intracellular pressure varied from ∼330 mmHg at the center to zero at the surface. We have several knockout/knock-in mouse models with differing levels of expression of gap junction channels coupling lens fiber cells. Intracellular hydrostatic pressure in lenses from these mouse models varied inversely with the number of channels. When the lens’ circulation of Na+ was either blocked or reduced, intracellular hydrostatic pressure in central fiber cells was either eliminated or reduced proportionally. These data are consistent with our hypotheses: fluid circulates through the lens; the intracellular leg of fluid circulation is through gap junction channels and is driven by hydrostatic pressure; and the fluid flow is generated by membrane transport of sodium. PMID:21624945

  13. Arsenolite: a quasi-hydrostatic solid pressure-transmitting medium

    NASA Astrophysics Data System (ADS)

    Sans, J. A.; Manjón, F. J.; Popescu, C.; Muñoz, A.; Rodríguez-Hernández, P.; Jordá, J. L.; Rey, F.

    2016-11-01

    This study reports the experimental characterization of the hydrostatic properties of arsenolite (As4O6), a molecular solid which is one of the softest minerals in the absence of hydrogen bonding. The high compressibility of arsenolite and its stability up to 15 GPa have been proved by x-ray diffraction measurements, and the progressive loss of hydrostaticity with increasing pressure up to 20 GPa has been monitored by ruby photoluminescence. Arsenolite has been found to exhibit hydrostatic behavior up to 2.5 GPa and a quasi-hydrostatic behavior up to 10 GPa at room temperature. This result opens the way to explore other molecular solids as possible quasi-hydrostatic pressure-transmitting media. The validity of arsenolite as an insulating, stable, non-penetrating and quasi-hydrostatic medium is explored by the study of the x-ray diffraction of zeolite ITQ-29 at high pressure.

  14. Heat transport and coupling modes in Rayleigh-Bénard convection occurring between two layers with largely different viscosities

    NASA Astrophysics Data System (ADS)

    Yoshida, Masaki; Iwamori, Hikaru; Hamano, Yozo; Suetsugu, Daisuke

    2017-09-01

    A high-resolution numerical simulation model in two-dimensional cylindrical geometry was used to discuss the heat transport and coupling modes in two-layer Rayleigh-Bénard convection with a high Rayleigh number (up to the order of 109), an infinite Prandtl number, and large viscosity contrasts (up to 10-3) between an outer, highly viscous layer (HVL) and an inner, low-viscosity layer (LVL). In addition to mechanical and thermal interaction across the HVL-LVL interface, which has been investigated by Yoshida and Hamano ["Numerical studies on the dynamics of two-layer Rayleigh-Bénard convection with an infinite Prandtl number and large viscosity contrasts," Phys. Fluids 28(11), 116601 (2016)], the spatiotemporal analysis in this study provides new insights into (1) heat transport over the entire system between the bottom of the LVL and the top of the HVL, in particular that associated with thermal plumes, and (2) the convection regime and coupling mode of the two layers, including the transition mechanism between the mechanical coupling mode at relatively low viscosity contrasts and the thermal coupling mode at higher viscosity contrasts. Although flow in the LVL is highly time-dependent, it shares the spatially opposite/same flow pattern synchronized to the nearly stationary upwelling and downwelling plumes in the HVL, corresponding to the mechanical/thermal coupling mode. In the transitional regime between the mechanical and thermal coupling modes, the LVL exhibits periodical switching between the two phases (i.e., the mechanical and thermal coupling phases) with a stagnant period. A detailed inspection revealed that the switching was initiated by the instability in the uppermost boundary layer of the LVL. These results suggest that convection in the highly viscous mantle of the Earth controls that of the extremely low-viscosity outer core in a top-down manner under the thermal coupling mode, which may support a scenario of top-down hemispherical dynamics

  15. Histologic effects of University of Wisconsin two-layer method preservation of rat pancreas.

    PubMed

    Gioviale, M C; Damiano, G; Puleio, R; Bellavia, M; Cassata, G; Palumbo, V D; Spinelli, G; Altomare, R; Barone, R; Cacciabaudo, F; Buscemi, G; Lo Monte, A I

    2013-06-01

    Marginal donors represent a poorly utilized source of organs for transplantation despite their availability. The key is to reduce the ischemic damage in the effort to improve organ quality. This study investigated the histologic effects after in situ perfusion of preservation with a two-layer method compared with the classic University of Wisconsin preservation in term of tissue integrity and number of viable exocrine cells in the rat pancreas both after exsanguination and at 8 weeks of cryopreservation. Pancreata harvested from 60 rats were collected using 3 methods: two-layer method following University of Wisconsin perfusion; exsanguination; and classic University of Wisconsin perfusion/storage. In addition to histologic analysis of collected pancreata, we analyzed the number of CK19(+) cells and their viability using chi-square tests with values P < .05 considered to be significant. Rat pancreas histology showed as University of Wisconsin in situ perfusion and preservation by the two-layer method to be more effective to maintain the morphologic integrity of both exocrine and endocrine tissues. There were a larger number of CK19(+) cells with good viability. Moreover, the effects of oxygenation were visible in pancreas biopsies preserved after exsanguination. In situ University of Wisconsin perfusion and preservation for 240 minutes with the two-layer method yielded greater numbers and viability of CK19(+) cells even after 8 weeks of cryopreservation.

  16. Analysis of Steam Heating of a Two-Layer TBP/N-Paraffin/Nitric Acid Mixtures

    SciTech Connect

    Laurinat, J.E.; Hassan, N.M.; Rudisill, T.S.; Askew, N.M.

    1998-07-22

    This report presents an analysis of steam heating of a two-layer tri-n-butyl phosphate (TBP)/n-paraffin-nitric acid mixture.The purpose of this study is to determine if the degree of mixing provided by the steam jet or by bubbles generated by the TBP/nitric acid reaction is sufficient to prevent a runaway reaction.

  17. Observations of Time-Dependent Behavior in the Two-Layer Rayleigh-Benard System

    NASA Technical Reports Server (NTRS)

    Andereck, C. David; Colovas, Peter W.; Degen, Michael M.

    1996-01-01

    In this paper we present results from experiments with a system consisting of two immiscible fluid layers in rectangular and annular geometries, driven by a vertical temperature gradient. Time-dependent variations in the type of coupling observed between the two layers are described and characterized.

  18. Cooperation in group-structured populations with two layers of interactions

    PubMed Central

    Zhang, Yanling; Fu, Feng; Chen, Xiaojie; Xie, Guangming; Wang, Long

    2015-01-01

    Recently there has been a growing interest in studying multiplex networks where individuals are structured in multiple network layers. Previous agent-based simulations of games on multiplex networks reveal rich dynamics arising from interdependency of interactions along each network layer, yet there is little known about analytical conditions for cooperation to evolve thereof. Here we aim to tackle this issue by calculating the evolutionary dynamics of cooperation in group-structured populations with two layers of interactions. In our model, an individual is engaged in two layers of group interactions simultaneously and uses unrelated strategies across layers. Evolutionary competition of individuals is determined by the total payoffs accrued from two layers of interactions. We also consider migration which allows individuals to move to a new group within each layer. An approach combining the coalescence theory with the theory of random walks is established to overcome the analytical difficulty upon local migration. We obtain the exact results for all “isotropic” migration patterns, particularly for migration tuned with varying ranges. When the two layers use one game, the optimal migration ranges are proved identical across layers and become smaller as the migration probability grows. PMID:26632251

  19. Single-layer versus two-layer stamps for reduced pressure thermal nanoimprint

    NASA Astrophysics Data System (ADS)

    Papenheim, Marc; Dhima, Khalid; Wang, Si; Steinberg, Christian; Scheer, Hella-Christin

    2015-11-01

    Low-pressure imprint is interesting to avoid stamp deformation, stamp failure as well as polymer recovery. When large-area stamps are prepared with a stepping procedure, low pressure is required to optimize the stitching. However, with low-pressure imprint, conformal contact between stamp and substrate is critical. Admittedly, the imprint pressure required for conformal contact depends on the stamp material and its thickness. To get an idea to which extent the imprint pressure can be reduced with a flexible stamp, we compared different stamp materials and stamp architectures, single-layer stamps and two-layer stamps. The two-layer stamps are replica stamps, where the structures were replicated in a thin layer of OrmoStamp, fixed by a backplane. On the background of plate theory, we deduce the pressure reduction compared to a Si stamp by calculating the respective pressure ratio, independent from geometries. In addition, temperature-induced issues are addressed which are of relevance for a thermal imprint process. These issues are related to the mismatch between the thermal expansion coefficients of the stamp and the substrate, and in case of a two-layer stamp, to the mismatch between the backplane material and the top layer. The latter results in temperature-induced stamp bending. On the basis of simple analytical calculations, the potential of single-layer stamps and two-layer stamps with respect to thermal imprint at reduced pressure is discussed and guidelines are provided to assess the imprint situation when replica stamps are used for imprint. The results demonstrate the attractiveness of two-layer stamps for reduced pressure nanoimprint, even in a temperature-based process.

  20. Annular Pressure Seals and Hydrostatic Bearings

    DTIC Science & Technology

    2006-11-01

    minimal effect on the entrance pressure into the seal. Pressures vs shaft speed 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 Rotor Speed (RPM...speed 3600 rpm water seal, L/D=0.50, c=0.190 mm, D=152 mm L/D=0.50 Pressures vs shaft speed 0 10 20 30 40 50 60 70 0 1000 2000 3000 4000 5000 6000 Rotor...surface speed. Annular Pressure Seals and Hydrostatic Bearings 11 - 12 RTO-EN-AVT-143 Leakage vs shaft speed 0 2 4 6 8 10 12 14 16 18 0 1000 2000

  1. Hydrostatic shoe bearing system for the TIM

    NASA Astrophysics Data System (ADS)

    Ruiz Schneider, Elfego; Sohn, Erika; Quiros-Pacheco, Fernando; Godoy, Javier; Farah Simon, Alejandro; Quintanilla, R.; Soto, P.; Salas, Luis; Cruz-Gonzales, Irene

    2000-08-01

    We present an active, low cost hydrostatic shoe bearing system for the Mexican Infrared Telescope which solves the suspension and motion of a 100 ton, 7.8 m telescope. Different geometries are analyzed to optimize the shoe's pressure print. These designs offer a self-adjusting action between the shoe's sliding path and the girth track. Different parameters such as pressure, temperature and proximity are measured and implemented into a control system in order to stabilize the bearing from the fluid's thermal viscosity effects. A simple method for fluid injection is discussed.

  2. Heat Transfer of Thermocapillary Convection in a Two-Layered Fluid System Under the Influence of Magnetic Field

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Ludovisis, D.; Cha, S. S.

    2006-01-01

    Heat transfer of a two-layer fluid system has been of great importance in a variety of industrial applications. For example, the phenomena of immiscible fluids can be found in materials processing and heat exchangers. Typically in solidification from a melt, the convective motion is the dominant factor that affects the uniformity of material properties. In the layered flow, thermocapillary forces can come into an important play, which was first emphasized by a previous investigator in 1958. Under extraterrestrial environments without gravity, thermocapillary effects can be a more dominant factor, which alters material properties in processing. Control and optimization of heat transfer in an immiscible fluid system need complete understanding of the flow phenomena that can be induced by surface tension at a fluid interface. The present work is focused on understanding of the magnetic field effects on thermocapillary convection, in order to optimize material processing. That is, it involves the study of the complicated phenomena to alter the flow motion in crystal growth. In this effort, the Marangoni convection in a cavity with differentially heated sidewalls is investigated with and without the influence of a magnetic field. As a first step, numerical analyses are performed, by thoroughly investigating influences of all pertinent physical parameters. Experiments are then conducted, with preliminary results, for comparison with the numerical analyses.

  3. Heat Transfer of Thermocapillary Convection in a Two-Layered Fluid System Under the Influence of Magnetic Field

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Ludovisis, D.; Cha, S. S.

    2006-01-01

    Heat transfer of a two-layer fluid system has been of great importance in a variety of industrial applications. For example, the phenomena of immiscible fluids can be found in materials processing and heat exchangers. Typically in solidification from a melt, the convective motion is the dominant factor that affects the uniformity of material properties. In the layered flow, thermocapillary forces can come into an important play, which was first emphasized by a previous investigator in 1958. Under extraterrestrial environments without gravity, thermocapillary effects can be a more dominant factor, which alters material properties in processing. Control and optimization of heat transfer in an immiscible fluid system need complete understanding of the flow phenomena that can be induced by surface tension at a fluid interface. The present work is focused on understanding of the magnetic field effects on thermocapillary convection, in order to optimize material processing. That is, it involves the study of the complicated phenomena to alter the flow motion in crystal growth. In this effort, the Marangoni convection in a cavity with differentially heated sidewalls is investigated with and without the influence of a magnetic field. As a first step, numerical analyses are performed, by thoroughly investigating influences of all pertinent physical parameters. Experiments are then conducted, with preliminary results, for comparison with the numerical analyses.

  4. Hydrostatic compression in glycerinated rabbit muscle fibers.

    PubMed

    Ranatunga, K W; Fortune, N S; Geeves, M A

    1990-12-01

    Glycerinated muscle fibers isolated from rabbit psoas muscle, and a number of other nonmuscle elastic fibers including glass, rubber, and collagen, were exposed to hydrostatic pressures of up to 10 MPa (100 Atm) to determine the pressure sensitivity of their isometric tension. The isometric tension of muscle fibers in the relaxed state (passive tension) was insensitive to increased pressure, whereas the muscle fiber tension in rigor state increased linearly with pressure. The tension of all other fiber types (except rubber) also increased with pressure; the rubber tension was pressure insensitive. The pressure sensitivity of rigor tension was 2.3 kN/m2/MPa and, in comparison with force/extension relation determined at atmospheric pressure, the hydrostatic compression in rigor muscle fibers was estimated to be 0.03% Lo/MPa. As reported previously, the active muscle fiber tension is depressed by increased pressure. The possible underlying basis of the different pressure-dependent tension behavior in relaxed, rigor, and active muscle is discussed.

  5. Effect of Elasticity on Capillary Compensated Flexible Multi-recess Hydrostatic Journal Bearing Operating with Micropolar Lubricant

    NASA Astrophysics Data System (ADS)

    Verma, Suresh; Kumar, Vijay; Gupta, Kapil Dev

    2016-01-01

    This paper presents a theoretical study of the effects of bearing shell deformation upon the performance characteristics of a capillary compensated multi-recess hydrostatic journal bearing system operating with micropolar lubricant. The finite element method has been used to solve the modified Reynolds' equation governing the micropolar lubricant flow in the bearing and the three dimensional elasticity equations governing the displacement field in the bearing shell. The elasto-hydrostatic performance characteristics of the bearing are presented for various values of micropolar parameters ( l m and N 2) and for a wide range of the deformation coefficient bar{C}d which takes into account the flexibility of the bearing shell. The computed results indicate that the influence of the bearing shell flexibility is quite significant on the performance characteristics of recessed hydrostatic journal bearing system operating with micropolar lubricant.

  6. Rough-to-smooth transition of an equilibrium neutral constant stress layer. [atmospheric flow over rough terrain

    NASA Technical Reports Server (NTRS)

    Logan, E., Jr.; Fichtl, G. H.

    1975-01-01

    A model is proposed for low-level atmospheric flows over terrains of changing roughness length, such as those found at the windward end of landing strips adjoining rough terrain. The proposed model is used to develop a prediction technique for calculating transition wind and shear-stress profiles in the region following surface roughness discontinuity. The model for the transition region comprises two layers: a logarithmic layer and a buffer layer. The flow is assumed to be steady, two-dimensional, and incompressible, with neutral hydrostatic stability. A diagram is presented for a typical wind profile in the transition region, obtained from the logarithmic and velocity defect profiles using shear stress calculated by relevant equations.

  7. 46 CFR 61.30-10 - Hydrostatic test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Hydrostatic test. 61.30-10 Section 61.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Tests and Inspections of Fired Thermal Fluid Heaters § 61.30-10 Hydrostatic test. All...

  8. A Simple Explanation of the Classic Hydrostatic Paradox

    ERIC Educational Resources Information Center

    Kontomaris, Stylianos-Vasileios; Malamou, Anna

    2016-01-01

    An interesting problem in fluid mechanics, with significant educational importance, is the classic hydrostatic paradox. The hydrostatic paradox states the fact that in different shaped containers, with the same base area, which are filled with a liquid of the same height, the applied force by the liquid on the base of each container is exactly the…

  9. A Simple Explanation of the Classic Hydrostatic Paradox

    ERIC Educational Resources Information Center

    Kontomaris, Stylianos-Vasileios; Malamou, Anna

    2016-01-01

    An interesting problem in fluid mechanics, with significant educational importance, is the classic hydrostatic paradox. The hydrostatic paradox states the fact that in different shaped containers, with the same base area, which are filled with a liquid of the same height, the applied force by the liquid on the base of each container is exactly the…

  10. 49 CFR 230.36 - Hydrostatic testing of boilers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Hydrostatic testing of boilers. 230.36 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Pressure Testing of Boilers § 230.36 Hydrostatic testing of boilers. (a) Time of test....

  11. 49 CFR 230.36 - Hydrostatic testing of boilers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Hydrostatic testing of boilers. 230.36 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Pressure Testing of Boilers § 230.36 Hydrostatic testing of boilers. (a) Time of test....

  12. 49 CFR 230.36 - Hydrostatic testing of boilers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Hydrostatic testing of boilers. 230.36 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Pressure Testing of Boilers § 230.36 Hydrostatic testing of boilers. (a) Time of test....

  13. 49 CFR 230.36 - Hydrostatic testing of boilers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Hydrostatic testing of boilers. 230.36 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Pressure Testing of Boilers § 230.36 Hydrostatic testing of boilers. (a) Time of test....

  14. 49 CFR 230.36 - Hydrostatic testing of boilers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Hydrostatic testing of boilers. 230.36 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Pressure Testing of Boilers § 230.36 Hydrostatic testing of boilers. (a) Time of test....

  15. Nonstationary Axisymmetric Temperature Field in a Two-Layer Slab Under Mixed Heating Conditions

    NASA Astrophysics Data System (ADS)

    Turchin, I. N.; Timar, I.; Kolodii, Yu. A.

    2015-09-01

    With the use of the Laguerre and Hankel integral transforms, the solution of a two-dimensional initial-boundary-value heat conduction problem for a two-layer slab under mixed boundary conditions is constructed: one of the surfaces is heated by a heat flux distributed axisymmetrically in a circle of radius R and is cooled by the Newton law outside this circle. The solution of the problem is reduced to a sequence of infinite quasi-regular systems of algebraic equations. The results of numerical analysis of the temperature field in the two-layer slab made from an aluminum alloy and ceramicsare presented depending on the relative geometric properties of the components and cooling intensity.

  16. Two-Layer Variable Infiltration Capacity Land Surface Representation for General Circulation Models

    NASA Technical Reports Server (NTRS)

    Xu, L.

    1994-01-01

    A simple two-layer variable infiltration capacity (VIC-2L) land surface model suitable for incorporation in general circulation models (GCMs) is described. The model consists of a two-layer characterization of the soil within a GCM grid cell, and uses an aerodynamic representation of latent and sensible heat fluxes at the land surface. The effects of GCM spatial subgrid variability of soil moisture and a hydrologically realistic runoff mechanism are represented in the soil layers. The model was tested using long-term hydrologic and climatalogical data for Kings Creek, Kansas to estimate and validate the hydrological parameters. Surface flux data from three First International Satellite Land Surface Climatology Project Field Experiments (FIFE) intensive field compaigns in the summer and fall of 1987 in central Kansas, and from the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) in Brazil were used to validate the mode-simulated surface energy fluxes and surface temperature.

  17. Rotational normal modes of triaxial two-layered anelastic Earth model

    NASA Astrophysics Data System (ADS)

    Yang, Zhuo; Shen, WenBin

    2016-04-01

    This study focuses on providing rotational normal modes of a triaxial two-layered anelastic Earth model with considering the electromagnetic coupling. We formulate the rotation equation of the triaxial two-layered anelastic Earth model and then provide solution of that equation. We obtain four mathematically possible solutions which might exist in reality. Based on present choice of the conventional reference systems, only two of these four solutions correspond to the real existing prograde Chandler wobble (CW) and the retrograde free core nutation (FCN). We provide the periods of CW and FCN as well as their quality factors based on various experiments and observations. This study is supported by National 973 Project China (grant No. 2013CB733305) and NSFC (grant Nos. 41174011, 41210006, 41429401).

  18. Low-frequency absorption using a two-layer system with active control of input impedance.

    PubMed

    Cobo, Pedro; Fernández, Alejandro; Doutres, Olivier

    2003-12-01

    Broadband noise absorption, including low frequencies, may be obtained by a hybrid passive-active two-layer system. A porous layer in front of an air layer provides passive absorption, at medium and high frequencies. Active control of the input impedance of the two-layer system yields absorption at low frequencies. The active control system can implement either pressure-release or impedance-matching conditions. A simple analytical model based upon plane waves propagating in a tube permits the comparison of both control strategies. The results of this simple model show that the pressure-release condition affords higher absorption than the impedance-matching condition for some combinations of geometrical and material parameters. Experimental results corroborate the good performance of the pressure-release condition under the prescribed geometrical setup.

  19. Nonlinear stability analysis of a two-layer thin liquid film: dewetting and autophobic behavior.

    PubMed

    Fisher, L S; Golovin, A A

    2005-11-15

    The nonlinear stability analysis of a liquid film composed of two superposed thin layers of immiscible liquids resting on a solid substrate is performed. It is shown that the coupling of van der Waals interactions in the two layers can lead to an autophobic behavior in the form of spinodal decomposition of two planar liquid layers into a system of localized drops divided by almost planar wetting layers. The results of the weakly nonlinear analysis near the instability threshold are confirmed by the numerical solution of a system of two strongly nonlinear evolution equations for the liquid-liquid and liquid-gas interfaces. The kinetics of the drop coarsening at late stages is studied and is found to be close to that reported for a one-layer film. It is also shown that gravity effects can become significant even for very thin two-layer films.

  20. Radiation efficiency and the gain of a source inside a two-layered grounded dielectric structure

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Arun K.

    1992-08-01

    The integral-transformation technique is used to derive the space- and surface-wave radiation fields generated by a source contained in a two-layered grounded dielectric structure. It is established that (1) surface wave loss leads to a substantial difference between the overall and the directive gain, (2) directivity and radiation efficiency are maximized at distinctive thicknesses of the dielectric layers, and (3) bandwidth decreases with increasing gain of the structure.

  1. On Theory of Dispersive Transport in a Two-Layer Polymer Structure

    NASA Astrophysics Data System (ADS)

    Sibatov, R. T.; Morozova, E. V.

    2016-09-01

    Dispersive transport of charge carriers in a two-layer polymer structure is modeled on the basis of the integrodifferential equation of hereditary diffusion. The model of multiple trapping in a bilayer is generalized to the case of an arbitrary density of localized states. With the help of an efficient Monte Carlo algorithm, curves of the transient current are calculated and their features are explained within the framework of a stochastic interpretation of the process.

  2. Propagation of solitary internal waves in two-layer ocean of variable depth

    NASA Astrophysics Data System (ADS)

    Talipova, T. G.; Kurkina, O. E.; Rouvinskaya, E. A.; Pelinovsky, E. N.

    2015-01-01

    The propagation of internal solitons of moderate amplitude in a two-layer ocean of variable depth is studied in terms of the Gardner and Euler equations. An analytical solution is obtained with the use of asymptotic expansions on a small parameter (bottom slope). The theoretical results are compared with the numerical modeling results. The possibility of soliton shape preservation during pulse propagation is discussed. It is obtained that, as the initial amplitude increases, the pulse deviates from the soliton shape more rapidly.

  3. Acoustic characteristics and the design of two-layered soundproof plates

    NASA Astrophysics Data System (ADS)

    Chonan, S.; Kugo, Y.

    1989-03-01

    This paper presents exact solutions for the coincidence frequency and the sound transmission loss of two-layered infinite plates excited by a plane acoustic wave. The problem is studied based on the two-dimensional elasticity theory wih the use of the Lame potential functions . A simple design method for a soundproof sheet with high transmission loss and high coincidence frequency is presented and illustrated with some examples. The results obtained are also compared with those from the thick plate theory.

  4. Visible/near-infrared spectra and two-layer modeling of palagonite-coated Basalts

    USGS Publications Warehouse

    Johnson, J. R.; Grundy, W.M.

    2001-01-01

    Fine-grained dust coatings on Martian rocks and soils obscure underlying surfaces and hinder mineralogic interpretations of both remote sensing and in-situ observations. We investigate laboratory visible/near-infrared spectra of various thicknesses of palagonite coatings on basalt substrates. We develop a two-layer Hapke scattering model incorporating porosity, grain size, and derived absorption coefficients of palagonite and basalt that reproduces the observed spectra only when the single scattering particle phase function is varied with wavelength.

  5. A Problem of Fatigue Fracture Mechanics of a Two-Layer Material with Edge Cracks

    NASA Astrophysics Data System (ADS)

    Seyfullayev, A. I.; Rustamova, M. A.; Kerimova, Sh. A.

    2017-07-01

    A problem for an elastic half-plane consisting of two tightly coupled homogeneous isotropic elastic media and containing edge cracks is considered. Its lateral surface is subjected to a given external load. The growth of a fatigue crack in the two-layer half-plane is investigated. For some materials, the number of cycles to failure is calculated. The stress intensity factor is determined, and a numerical analysis is performed.

  6. Shapes and gravitational fields of rotating two-layer Maclaurin ellipsoids: Application to planets and satellites

    NASA Astrophysics Data System (ADS)

    Schubert, Gerald; Anderson, John; Zhang, Keke; Kong, D.; Helled, Ravit

    2011-08-01

    The exact solution for the shape and gravitational field of a rotating two-layer Maclaurin ellipsoid of revolution is compared with predictions of the theory of figures up to third order in the small rotational parameter of the theory of figures. An explicit formula is derived for the external gravitational coefficient J2 of the exact solution. A new approach to the evaluation of the theory of figures based on numerical integration of ordinary differential equations is presented. The classical Radau-Darwin formula is found not to be valid for the rotational parameter ɛ2 = Ω2/(2 πG ρ2) ⩾ 0.17 since the formula then predicts a surface eccentricity that is smaller than the eccentricity of the core-envelope boundary. Interface eccentricity must be smaller than surface eccentricity. In the formula for ɛ2, Ω is the angular velocity of the two-layer body, ρ2 is the density of the outer layer, and G is the gravitational constant. For an envelope density of 3000 kg m -3 the failure of the Radau-Darwin formula corresponds to a rotation period of about 3 h. Application of the exact solution and the theory of figures is made to models of Earth, Mars, Uranus, and Neptune. The two-layer model with constant densities in the layers can provide realistic approximations to terrestrial planets and icy outer planet satellites. The two-layer model needs to be generalized to allow for a continuous envelope (outer layer) radial density profile in order to realistically model a gas or ice giant planet.

  7. Zinc-impregnated and odour-control two-layer compression.

    PubMed

    Stephen-Haynes, Jackie; Callaghan, Rosie

    This article presents the results of 40 patients using two versions of a new two-layer compression system in a large primary care organisation. The evaluation was undertaken to explore the following areas formulary inclusion consideration: ease of use, clinical acceptability, clinical outcome and additional patient benefits of an alternative new low-profile bandage system containing zinc (n=30) and odour-control properties (n=10).

  8. Dynamic force response of spherical hydrostatic journal bearings for cryogenic applications

    NASA Astrophysics Data System (ADS)

    Andres, Luis San

    1994-07-01

    Hydrostatic journal bearings are ideal elements to replace roller bearings as rotor support elements in cryogenic turbomachinery. These bearings will be used for primary space-power applications due to their long lifetime, low friction and wear, large load capacity, and direct stiffness and damping force coefficients. The performance characteristics of turbulent flow, orifice compensated, spherical hydrostatic journal bearings are presented. These bearing allow tolerance for shaft misalignment without force degradation and are able to support axial loads, thus providing a design configuration which could be used efficiently on high-performance turbomachinery. Bulk-flow mass and momentum equations for the motion of a variable properties liquid on the thin film bearing lands are solved numerically. Predictions of load capacity and force coefficients for a six recess, spherical hydrostatic bearing in a liquid oxygen environment are presented. Fluid film axial forces and dynamic coefficients of a magnitude about 20 percent of the radial load capacity are calculated for the case analyzed. Fluid inertia effects, advective and centrifugal, are found to greatly affect the static and dynamic force characteristics of the bearing studied.

  9. Hydrodynamic and hydrostatic modelling of hydraulic journal bearings considering small displacement condition

    NASA Astrophysics Data System (ADS)

    Chen, Chi-Yin; Chuang, Jen-Chen; Tu, Jia-Ying

    2016-09-01

    This paper proposes modified coefficients for the dynamic model of hydraulic journal bearing system that integrates the hydrodynamic and hydrostatic properties. In recent years, design of hydraulic bearing for machine tool attracts worldwide attention, because hydraulic bearings are able to provide higher capacity and accuracy with lower friction, compared to conventional bearing systems. In order to achieve active control of the flow pressure and enhance the operation accuracy, the dynamic model of hydraulic bearings need to be developed. Modified coefficients of hydrostatic stiffness, hydrodynamic stiffness, and squeeze damping of the dynamic model are presented in this work, which are derived referring to small displacement analysis from literature. The proposed modified coefficients and model, which consider the pressure variations, relevant geometry size, and fluid properties of the journal bearings, are able to characterise the hydrodynamic and hydrostatic properties with better precision, thus offering the following pragmatic contribution: (1) on-line prediction of the eccentricity and the position of the shaft in the face of external force that results in vibration; (2) development of active control system to regulate the supply flow pressure and to minimize the eccentricity of the shaft. Theoretical derivation and simulation results with different vibration cases are discussed to verify the proposed techniques.

  10. Quantifying the properties of two-layer turbid media with frequency-domain diffuse reflectance.

    PubMed

    Pham, T H; Spott, T; Svaasand, L O; Tromberg, B J

    2000-09-01

    Noncontact, frequency-domain measurements of diffusely reflected light are used to quantify optical properties of two-layer tissuelike turbid media. The irradiating source is a sinusoidal intensity-modulated plane wave, with modulation frequencies ranging from 10 to 1500 MHz. Frequency-dependent phase and amplitude of diffusely reflected photon density waves are simultaneously fitted to a diffusion-based two-layer model to quantify absorption (mu(a)) and reduced scattering (mu(s)') parameters of each layer as well as the upper-layer thickness (l). Study results indicate that the optical properties of two-layer media can be determined with a percent accuracy of the order of +/-9% and +/-5% for mu(a) and mu(s)', respectively. The accuracy of upper-layer thickness (l) estimation is as good as +/-6% when optical properties of upper and lower layers are known. Optical property and layer thickness prediction accuracy degrade significantly when more than three free parameters are extracted from data fits. Problems with convergence are encountered when all five free parameters (mu(a) and mu(s)' of upper and lower layers and thickness l) must be deduced.

  11. Long-term persistence of oil from the Exxon Valdez spill in two-layer beaches

    NASA Astrophysics Data System (ADS)

    Li, Hailong; Boufadel, Michel C.

    2010-02-01

    Oil spilled from the tanker Exxon Valdez in 1989 (refs 1, 2) persists in the subsurface of gravel beaches in Prince William Sound, Alaska. The contamination includes considerable amounts of chemicals that are harmful to the local fauna. However, remediation of the beaches was stopped in 1992, because it was assumed that the disappearance rate of oil was large enough to ensure a complete removal of oil within a few years. Here we present field data and numerical simulations of a two-layered beach with a small freshwater recharge in the contaminated area, where a high-permeability upper layer is underlain by a low-permeability lower layer. We find that the upper layer temporarily stored the oil, while it slowly and continuously filled the lower layer wherever the water table dropped below the interface of the two layers, as a result of low freshwater recharge from the land. Once the oil entered the lower layer, it became entrapped by capillary forces and persisted there in nearly anoxic conditions that are a result of the tidal hydraulics in the two-layered beaches. We suggest that similar dynamics could operate on tidal gravel beaches around the world, which are particularly common in mid- and high-latitude regions, with implications for locating spilled oil and for its biological remediation.

  12. Extremum method: Inverse solution of the two-layer thermal wave problem

    NASA Astrophysics Data System (ADS)

    Nzodoum Fotsing, J. L.; Gibkes, J.; Pelzl, J.; Bein, B. K.

    2005-09-01

    An inverse solution of the two-layer thermal wave problem has been derived, which allows us to determine the relevant thermal transport parameters, the thermal diffusion time and the thermal reflection coefficient, respectively, the ratio of the effusivities of the two layers, deduced from the relative minimum or maximum of the calibrated phase lags measured between the periodically modulated excitation of the thermal wave and the detected thermal response. Applying a functional transformation by multiplying the calibrated phase lags with the variable (1/f1/2)q, where f is the modulation frequency of excitation and q a positive or negative real number close to zero, the inversion method is extended to other values of the calibrated phase lags measured in the neighborhood of the phase minimum or maximum. The application potential of these two solution methods is studied by analyzing the phase lags measured as a function of frequency for two-layer systems of technological importance, e.g., different plasma-deposited hard coatings on tool steel, coated cutting tools after friction wear, and a sample of a shape memory alloy (NiTi) after mechanical surface treatment.

  13. Phase transitions and kinetic properties of gold nanoparticles confined between two-layer graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Wu, Nanhua; Chen, Jionghua; Wang, Jinjian; Shao, Jingling; Zhu, Xiaolei; Lu, Xiaohua; Guo, Lucun

    2016-11-01

    The thermodynamic and kinetic behaviors of gold nanoparticles confined between two-layer graphene nanosheets (two-layer-GNSs) are examined and investigated during heating and cooling processes via molecular dynamics (MD) simulation technique. An EAM potential is applied to represent the gold-gold interactions while a Lennard-Jones (L-J) potential is used to describe the gold-GNS interactions. The MD melting temperature of 1345 K for bulk gold is close to the experimental value (1337 K), confirming that the EAM potential used to describe gold-gold interactions is reliable. On the other hand, the melting temperatures of gold clusters supported on graphite bilayer are corrected to the corresponding experimental values by adjusting the εAu-C value. Therefore, the subsequent results from current work are reliable. The gold nanoparticles confined within two-layer GNSs exhibit face center cubic structures, which is similar to those of free gold clusters and bulk gold. The melting points, heats of fusion, and heat capacities of the confined gold nanoparticles are predicted based on the plots of total energies against temperature. The density distribution perpendicular to GNS suggests that the freezing of confined gold nanoparticles starts from outermost layers. The confined gold clusters exhibit layering phenomenon even in liquid state. The transition of order-disorder in each layer is an essential characteristic in structure for the freezing phase transition of the confined gold clusters. Additionally, some vital kinetic data are obtained in terms of classical nucleation theory.

  14. Efficient non-hydrostatic modelling of 3D wave-induced currents using a subgrid approach

    NASA Astrophysics Data System (ADS)

    Rijnsdorp, Dirk P.; Smit, Pieter B.; Zijlema, Marcel; Reniers, Ad J. H. M.

    2017-08-01

    Wave-induced currents are an ubiquitous feature in coastal waters that can spread material over the surf zone and the inner shelf. These currents are typically under resolved in non-hydrostatic wave-flow models due to computational constraints. Specifically, the low vertical resolutions adequate to describe the wave dynamics - and required to feasibly compute at the scales of a field site - are too coarse to account for the relevant details of the three-dimensional (3D) flow field. To describe the relevant dynamics of both wave and currents, while retaining a model framework that can be applied at field scales, we propose a two grid approach to solve the governing equations. With this approach, the vertical accelerations and non-hydrostatic pressures are resolved on a relatively coarse vertical grid (which is sufficient to accurately resolve the wave dynamics), whereas the horizontal velocities and turbulent stresses are resolved on a much finer subgrid (of which the resolution is dictated by the vertical scale of the mean flows). This approach ensures that the discrete pressure Poisson equation - the solution of which dominates the computational effort - is evaluated on the coarse grid scale, thereby greatly improving efficiency, while providing a fine vertical resolution to resolve the vertical variation of the mean flow. This work presents the general methodology, and discusses the numerical implementation in the SWASH wave-flow model. Model predictions are compared with observations of three flume experiments to demonstrate that the subgrid approach captures both the nearshore evolution of the waves, and the wave-induced flows like the undertow profile and longshore current. The accuracy of the subgrid predictions is comparable to fully resolved 3D simulations - but at much reduced computational costs. The findings of this work thereby demonstrate that the subgrid approach has the potential to make 3D non-hydrostatic simulations feasible at the scale of a

  15. Filtration coefficient of the axon membrane as measured with hydrostatic and osmotic methods.

    PubMed

    Vargas, F F

    1968-01-01

    The hydraulic conductivity of the membranes surrounding the giant axon of the squid, Dosidicus gigas, was measured. In some axons the axoplasm was partially removed by suction. Perfusion was then established by insertion of a second pipette. In other axons the axoplasm was left intact and only one pipette was inserted. In both groups hydrostatic pressure was applied by means of a water column in a capillary manometer. Displacement of the meniscus in time gave the rate of fluid flowing across the axon sheath. In both groups osmotic differences across the membrane were established by the addition of a test molecule to the external medium which was seawater. The hydraulic conductivity determined by application of hydrostatic pressure was 10.6 +/- 0.8.10(-8) cm/sec cm H(2)O in perfused axons and 3.2 +/- 0.6.10(-8) cm/sec cm H(2)O in intact axons. When the driving force was an osmotic pressure gradient the conductivity was 4.5 +/- 0.6 x 10(-10) cm/sec cm H(2)O and 4.8 +/- 0.9 x 10(-10) cm/sec cm H(2)O in perfused and intact axons, respectively. A comparable result was found when the internal solution was made hyperosmotic. The fluid flow was a linear function of the hydrostatic pressure up to 70 cm of water. Glycerol outflux and membrane conductance were increased 1.6 and 1.1 times by the application of hydrostatic pressure. These increments do not give an explanation of the difference between the filtration coefficients. Other possible explanations are suggested and discussed.

  16. Computer simulations of 3C-SiC under hydrostatic and non-hydrostatic stresses.

    PubMed

    Guedda, H Z; Ouahrani, T; Morales-García, A; Franco, R; Salvadó, M A; Pertierra, P; Recio, J M

    2016-03-21

    The response of 3C-SiC to hydrostatic pressure and to several uni- and bi-axial stress conditions is thoroughly investigated using first principles calculations. A topological interpretation of the chemical bonding reveals that the so-called non-covalent interactions enhance only at high pressure while the nature of the covalent Si-C bonding network keeps essentially with the same pattern. The calculated low compressibility agrees well with experimental values and is in concordance with the high structural stability of this polymorph under hydrostatic pressure. Under uniaxial [001] stress, the c/a ratio shows a noticeable drop inducing a closure of the band gap and the emergence of a metallic state around 40 GPa. This behavior correlates with a plateau of the electron localization function exhibiting a roughly constant and non-negligible value surrounding CSi4 and SiC4 covalent bonded units.

  17. Influence of supraglottal structures on the glottal jet exiting a two-layer synthetic, self-oscillating vocal fold model

    PubMed Central

    Drechsel, James S.; Thomson, Scott L.

    2008-01-01

    A synthetic two-layer, self-oscillating, life-size vocal fold model was used to study the influence of the vocal tract and false folds on the glottal jet. The model vibrated at frequencies, pressures, flow rates, and amplitudes consistent with human phonation, although some differences in behavior between the model and the human vocal folds are noted. High-speed images of model motion and flow visualization were acquired. Phase-locked ensemble-averaged glottal jet velocity measurements using particle image velocimetry (PIV) were acquired with and without an idealized vocal tract, with and without false folds. PIV data were obtained with varying degrees of lateral asymmetric model positioning. Glottal jet velocity magnitudes were consistent with those measured using excised larynges. A starting vortex was observed in all test cases. The false folds interfered with the starting vortex, and in some cases vortex shedding from the false folds was observed. In asymmetric cases without false folds, the glottal jet tended to skew toward the nearest wall; with the false folds, the opposite trend was observed. rms velocity calculations showed the jet shear layer and laminar core. The rms velocities were higher in the vocal tract cases compared to the open jet and false fold cases. PMID:18537394

  18. Food processing by high hydrostatic pressure.

    PubMed

    Yamamoto, Kazutaka

    2017-04-01

    High hydrostatic pressure (HHP) process, as a nonthermal process, can be used to inactivate microbes while minimizing chemical reactions in food. In this regard, a HHP level of 100 MPa (986.9 atm/1019.7 kgf/cm(2)) and more is applied to food. Conventional thermal process damages food components relating color, flavor, and nutrition via enhanced chemical reactions. However, HHP process minimizes the damages and inactivates microbes toward processing high quality safe foods. The first commercial HHP-processed foods were launched in 1990 as fruit products such as jams, and then some other products have been commercialized: retort rice products (enhanced water impregnation), cooked hams and sausages (shelf life extension), soy sauce with minimized salt (short-time fermentation owing to enhanced enzymatic reactions), and beverages (shelf life extension). The characteristics of HHP food processing are reviewed from viewpoints of nonthermal process, history, research and development, physical and biochemical changes, and processing equipment.

  19. Hydrostatic Stress Effect On the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2002-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has no effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of notched geometries. New experiments and nonlinear finite element analyses (FEA) of Inconel 100 (IN 100) equal-arm bend and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions was performed. In all test cases, the von Mises constitutive model, which is independent of hydrostatic pressure, overestimated the load for a given displacement or strain. Considering the failure displacements or strains, the Drucker-Prager FEMs predicted loads that were 3% to 5% lower than the von Mises values. For the failure loads, the Drucker Prager FEMs predicted strains that were 20% to 35% greater than the von Mises values. The Drucker-Prager yield function seems to more accurately predict the overall specimen response of geometries with significant internal hydrostatic stress influence.

  20. Effects of Hydrostatic Pressure on Carcinogenic Properties of Epithelia

    PubMed Central

    Tokuda, Shinsaku; Kim, Young Hak; Matsumoto, Hisako; Muro, Shigeo; Hirai, Toyohiro; Mishima, Michiaki; Furuse, Mikio

    2015-01-01

    The relationship between chronic inflammation and cancer is well known. The inflammation increases the permeability of blood vessels and consequently elevates pressure in the interstitial tissues. However, there have been only a few reports on the effects of hydrostatic pressure on cultured cells, and the relationship between elevated hydrostatic pressure and cell properties related to malignant tumors is less well understood. Therefore, we investigated the effects of hydrostatic pressure on the cultured epithelial cells seeded on permeable filters. Surprisingly, hydrostatic pressure from basal to apical side induced epithelial stratification in Madin-Darby canine kidney (MDCK) I and Caco-2 cells, and cavities with microvilli and tight junctions around their surfaces were formed within the multi-layered epithelia. The hydrostatic pressure gradient also promoted cell proliferation, suppressed cell apoptosis, and increased transepithelial ion permeability. The inhibition of protein kinase A (PKA) promoted epithelial stratification by the hydrostatic pressure whereas the activation of PKA led to suppressed epithelial stratification. These results indicate the role of the hydrostatic pressure gradient in the regulation of various epithelial cell functions. The findings in this study may provide clues for the development of a novel strategy for the treatment of the carcinoma. PMID:26716691

  1. Effects of Hydrostatic Pressure on Carcinogenic Properties of Epithelia.

    PubMed

    Tokuda, Shinsaku; Kim, Young Hak; Matsumoto, Hisako; Muro, Shigeo; Hirai, Toyohiro; Mishima, Michiaki; Furuse, Mikio

    2015-01-01

    The relationship between chronic inflammation and cancer is well known. The inflammation increases the permeability of blood vessels and consequently elevates pressure in the interstitial tissues. However, there have been only a few reports on the effects of hydrostatic pressure on cultured cells, and the relationship between elevated hydrostatic pressure and cell properties related to malignant tumors is less well understood. Therefore, we investigated the effects of hydrostatic pressure on the cultured epithelial cells seeded on permeable filters. Surprisingly, hydrostatic pressure from basal to apical side induced epithelial stratification in Madin-Darby canine kidney (MDCK) I and Caco-2 cells, and cavities with microvilli and tight junctions around their surfaces were formed within the multi-layered epithelia. The hydrostatic pressure gradient also promoted cell proliferation, suppressed cell apoptosis, and increased transepithelial ion permeability. The inhibition of protein kinase A (PKA) promoted epithelial stratification by the hydrostatic pressure whereas the activation of PKA led to suppressed epithelial stratification. These results indicate the role of the hydrostatic pressure gradient in the regulation of various epithelial cell functions. The findings in this study may provide clues for the development of a novel strategy for the treatment of the carcinoma.

  2. Gravity, the hydrostatic indifference concept and the cardiovascular system.

    PubMed

    Hinghofer-Szalkay, Helmut

    2011-02-01

    Gravity, like any acceleration, causes a hydrostatic pressure gradient in fluid-filled bodily compartments. At a force of 1G, this pressure gradient amounts to 10 kPa/m. Postural changes alter the distribution of hydrostatic pressure patterns according to the body's alignment to the acceleration field. At a certain location--referred to as hydrostatically indifferent--within any given fluid compartment, pressure remains constant during a given change of position relative to the acceleration force acting upon the body. At this specific location, there is probably little change in vessel volume, wall tension, and the balance of Starling forces after a positional manoeuvre. In terms of cardiac function, this is important because arterial and venous hydrostatic indifference locations determine postural cardiac preload and afterload changes. Baroreceptors pick up pressure signals that depend on their respective distance to hydrostatic indifference locations with any change of body position. Vascular shape, filling volume, and compliance, as well as temperature, nervous and endocrine factors, drugs, and time all influence hydrostatic indifference locations. This paper reviews the physiology of pressure gradients in the cardiovascular system that are operational in a gravitational/acceleration field, offers a broadened hydrostatic indifference concept, and discusses implications that are relevant in physiological and clinical terms.

  3. A robust, finite element model for hydrostatic surface water flows

    USGS Publications Warehouse

    Walters, R.A.; Casulli, V.

    1998-01-01

    A finite element scheme is introduced for the 2-dimensional shallow water equations using semi-implicit methods in time. A semi-Lagrangian method is used to approximate the effects of advection. A wave equation is formed at the discrete level such that the equations decouple into an equation for surface elevation and a momentum equation for the horizontal velocity. The convergence rates and relative computational efficiency are examined with the use of three test cases representing various degrees of difficulty. A test with a polar-quadrant grid investigates the response to local grid-scale forcing and the presence of spurious modes, a channel test case establishes convergence rates, and a field-scale test case examines problems with highly irregular grids.A finite element scheme is introduced for the 2-dimensional shallow water equations using semi-implicit methods in time. A semi-Lagrangian method is used to approximate the effects of advection. A wave equation is formed at the discrete level such that the equations decouple into an equation for surface elevation and a momentum equation for the horizontal velocity. The convergence rates and relative computational efficiency are examined with the use of three test cases representing various degrees of difficulty. A test with a polar-quadrant grid investigates the response to local grid-scale forcing and the presence of spurious modes, a channel test case establishes convergence rates, and a field-scale test case examines problems with highly irregular grids.

  4. A two-layered mechanical model of the rat esophagus. Experiment and theory

    PubMed Central

    Fan, Yanhua; Gregersen, Hans; Kassab, Ghassan S

    2004-01-01

    Background The function of esophagus is to move food by peristaltic motion which is the result of the interaction of the tissue forces in the esophageal wall and the hydrodynamic forces in the food bolus. The structure of the esophagus is layered. In this paper, the esophagus is treated as a two-layered structure consisting of an inner collagen-rich submucosa layer and an outer muscle layer. We developed a model and experimental setup for determination of elastic moduli in the two layers in circumferential direction and related the measured elastic modulus of the intact esophagus to the elastic modulus computed from the elastic moduli of the two layers. Methods Inflation experiments were done at in vivo length and pressure-diameters relations were recorded for the rat esophagus. Furthermore, the zero-stress state was taken into consideration. Results The radius and the strain increased as function of pressure in the intact as well as in the individual layers of the esophagus. At pressures higher than 1.5 cmH2O the muscle layer had a larger radius and strain than the mucosa-submucosa layer. The strain for the intact esophagus and for the muscle layer was negative at low pressures indicating the presence of residual strains in the tissue. The stress-strain curve for the submucosa-mucosa layer was shifted to the left of the curves for the muscle layer and for the intact esophagus at strains higher than 0.3. The tangent modulus was highest in the submucosa-mucosa layer, indicating that the submucosa-mucosa has the highest stiffness. A good agreement was found between the measured elastic modulus of the intact esophagus and the elastic modulus computed from the elastic moduli of the two separated layers. PMID:15518591

  5. Mass transfer model for two-layer TBP oxidation reactions: Revision 1

    SciTech Connect

    Laurinat, J.E.

    1994-11-04

    To prove that two-layer, TBP-nitric acid mixtures can be safely stored in the Canyon evaporators, it must be demonstrated that a runaway reaction between TBP and nitric acid will not occur. Previous bench-scale experiments showed that, at typical evaporator temperatures, this reaction is endothermic and therefore cannot run away, due to the loss of heat from evaporation of water in the organic layer. However, the reaction would be exothermic and could run away if the small amount of water in the organic layer evaporates before the nitric acid in this layer is consumed by the reaction. Provided that there is enough water in the aqueous layer, this would occur if the organic layer is sufficiently thick so that the rate of loss of water by evaporation exceeds the rate of replenishment due to mixing with the aqueous layer. Bubbles containing reaction products enhance the rate of transfer of water from the aqueous layer to the organic layer. These bubbles are generated by the oxidation of TBP and its reaction products in the organic layer and by the oxidation of butanol in the aqueous layer. Butanol is formed by the hydrolysis of TBP in the organic layer. For aqueous-layer bubbling to occur, butanol must transfer into the aqueous layer. Consequently, the rate of oxidation and bubble generation in the aqueous layer strongly depends on the rate of transfer of butanol from the organic to the aqueous layer. This report presents measurements of mass transfer rates for the mixing of water and butanol in two-layer, TBP-aqueous mixtures, where the top layer is primarily TBP and the bottom layer is comprised of water or aqueous salt solution. Mass transfer coefficients are derived for use in the modeling of two-layer TBP-nitric acid oxidation experiments.

  6. Facile preparation of porous alumina through-hole masks for sputtering by two-layer anodization

    NASA Astrophysics Data System (ADS)

    Yanagishita, Takashi; Masuda, Hideki

    2016-08-01

    Highly ordered porous alumina through-hole masks were fabricated on a substrate by combining two-layer anodization with subsequent through-holing by selective etching. This process allowed the fabrication of porous alumina masks without an increase in pore size during the etching performed for through-holing. Additionally, the process contributed to improved operability in the setting of the masks on substrates because the second anodizing layer acts as a supporting layer for the handling of the mask. The fabrication of ordered Au nanodot arrays was demonstrated as an example application of the through-hole masks obtained by the present process.

  7. Effect of eddy diffusivity on wind-driven currents in a two-layer stratified lake

    NASA Technical Reports Server (NTRS)

    Gedney, R. T.; Lick, W.; Molls, F. B.

    1972-01-01

    The steady state wind-driven circulation was numerically calculated in a rectangular stratified lake. The lake is composed of two layers having uniform but unequal densities and eddy diffusivities. The position in thermocline and the three-dimensional velocities in both layers calculated using shallow lake equations. The results show that, as the eddy diffusivity in the hypolimnion is increased, the thermocline tilt and hypolimnetic velocities increase. The effect of the other variables such as wind stress, density, basin length, and mean thermocline depth are also shown.

  8. The Dowling Wall Pressure-Spectrum Analogy Applied to an Isotropic Two-Layered Elastic Medium.

    DTIC Science & Technology

    2014-09-26

    A D-A±96 009 THE DOWLING WALL PRESSURE-SPECTRUN ANALOGY APPLIED TO 1/1 AN ISOTROPIC TIO-LA.. (U) NAVL UNDERW TER SYSTEMS CENTER MEW LONDON CT MEW...STANDM *monCP NESUflIT TEST aont NUSC Tehnical Report 7235 14 November 1984 C in I -O o The Dowling Wall Pressure-Spectrum * .Analogy Applied to an...CI&aa490V *THE DOWLING WALL PRESSURE-SPECTRUM ANALOGY APPLIED TO AN ISOTROPIC TWO-LAYERED ELASTIC MEDIUM * 12. PERSONAL AUTHOR(S * Craig A. Wagner 13a

  9. Orthogonal relation of elastic modes in two-layered plate with weak interface

    NASA Astrophysics Data System (ADS)

    Du, Jun; Cheng, Jianchun

    2002-05-01

    The orthogonal features of the guided wave-modes have been discussed in details for a two-layered plate with a weak interface. The elastic operator is proved to be a self-adjoint operator under the weak interface modeled by the spring model. However, it is proved to be non-self-adjoint operator, and a new orthogonal relation is derived for the weak interface modeled by the density model. The theoretical analyses are verified by numerical calculations for the spring model.

  10. Trapped modes around freely floating bodies in a two-layer fluid channel

    PubMed Central

    Cal, Filipe S.; Dias, Gonçalo A. S.; Videman, Juha H.

    2014-01-01

    Unlike the trapping of time-harmonic water waves by fixed obstacles, the oscillation of freely floating structures gives rise to a complex nonlinear spectral problem. Still, through a convenient elimination scheme the system simplifies to a linear spectral problem for a self-adjoint operator in a Hilbert space. Under symmetry assumptions on the geometry of the fluid domain, we present conditions guaranteeing the existence of trapped modes in a two-layer fluid channel. Numerous examples of floating bodies supporting trapped modes are given. PMID:25294970

  11. A Two-Layered Model for Dynamic Supply Chain Management Considering Transportation Constraint

    NASA Astrophysics Data System (ADS)

    Tanimizu, Yoshitaka; Harada, Kana; Ozawa, Chisato; Iwamura, Koji; Sugimura, Nobuhiro

    This research proposes a two-layered model for dynamic supply chain management considering transportation constraint. The model provides a method for suppliers to estimate suitable prices and delivery times of products based on not only production schedules but also transportation plans in consideration of constraints about shipping times and loading capacities for transportation. A prototype of dynamic supply chain simulation system was developed and some computational experiments were carried out in order to verify the effectiveness of the model. The prototype system is available to determine suitable shipping times and loading capacities of transportation vehicles.

  12. Two-layer synchronized ternary quantum-dot cellular automata wire crossings.

    PubMed

    Bajec, Iztok Lebar; Pečar, Primož

    2012-04-16

    : Quantum-dot cellular automata are an interesting nanoscale computing paradigm. The introduction of the ternary quantum-dot cell enabled ternary computing, and with the recent development of a ternary functionally complete set of elementary logic primitives and the ternary memorizing cell design of complex processing structures is becoming feasible. The specific nature of the ternary quantum-dot cell makes wire crossings one of the most problematic areas of ternary quantum-dot cellular automata circuit design. We hereby present a two-layer wire crossing that uses a specific clocking scheme, which ensures the crossed wires have the same effective delay.

  13. Low frequency soundproof characteristics of orthotropic two-layered cylindrical shells

    NASA Astrophysics Data System (ADS)

    Chonan, S.

    1988-11-01

    This paper is concerned with the acoustic characteristics of infinitely long, two-layered orthotropic cylindrical shells excited by a low frequency plane sound wave travelling axially within the shells. The problem is studied based on a thick shell theory, in which each layer is modeled as a single orthotropic shell and the two sets of shell equations are combined together by the continuity conditions of the displacements and tractions at the shell interface. The sound transmission loss through the shell wall, TL, for the axisymmetric acoustic mode ( n = 0) is obtained and calculated for various values of the physical parameters involved.

  14. Quadrupolar Effect on Two Layered Thin Film Antiferroelectric Smectic Liquid Crystal

    SciTech Connect

    Lum, Chia-Yuee; Ong, Lye-Hock; Cepic, Mojca

    2011-03-30

    Within the framework of the discrete Landau phenomenological model, the free energy of an antiferroelectric smectic liquid crystal is analyzed. This model considers the interactions between the liquid crystal molecules within the nearest and the next nearest layers. Electrostatic quadrupolar interaction up to the nearest layers is included. This quadrupolar term, b{sub q{xi}}???{sub i{center_dot}{xi}}???{sub i+1}{sup 2} is positive, thus favouring a perpendicular orientation in the adjacent layer respectively. We show how quadrupolar interaction can affects the planar regions of the phase diagram of a two layered thin antiferroelectric smectic liquid crystal film.

  15. Electron spin polarization by isospin ordering in correlated two-layer quantum Hall systems.

    PubMed

    Tiemann, L; Wegscheider, W; Hauser, M

    2015-05-01

    Enhancement of the electron spin polarization in a correlated two-layer, two-dimensional electron system at a total Landau level filling factor of 1 is reported. Using resistively detected nuclear magnetic resonance, we demonstrate that the electron spin polarization of two closely spaced two-dimensional electron systems becomes maximized when interlayer Coulomb correlations establish spontaneous isospin ferromagnetic order. This correlation-driven polarization dominates over the spin polarizations of competing single-layer fractional quantum Hall states under electron density imbalances.

  16. Trapped modes around freely floating bodies in a two-layer fluid channel.

    PubMed

    Cal, Filipe S; Dias, Gonçalo A S; Videman, Juha H

    2014-10-08

    Unlike the trapping of time-harmonic water waves by fixed obstacles, the oscillation of freely floating structures gives rise to a complex nonlinear spectral problem. Still, through a convenient elimination scheme the system simplifies to a linear spectral problem for a self-adjoint operator in a Hilbert space. Under symmetry assumptions on the geometry of the fluid domain, we present conditions guaranteeing the existence of trapped modes in a two-layer fluid channel. Numerous examples of floating bodies supporting trapped modes are given.

  17. Design of a two-layer optical interconnection network with a routing node

    NASA Astrophysics Data System (ADS)

    Kong, Fanmin; Jing, Wencai; Zhang, Yimo; Tang, Feng; Sun, Zhixiang

    2005-02-01

    An 8-channel switching node with routing function is designed in this paper using a high-performance digital cross-point switch. The throughput of the 8-channel routing node is 10 Gbit/s. Combined with time division multiplexing (TDM) technique, a high-speed optical interconnection network was designed. Using Optical Network Interface Cards (ONIC) and the designed routing node, a two-layer optical interconnection network with structure of ring and star topology is designed. Based on circuits cascading technique, the network can be expanded to meet the request of large scale data communication with low communication latency.

  18. Solitary SH waves in two-layered traction-free plates

    NASA Astrophysics Data System (ADS)

    Djeran-Maigre, Irini; Kuznetsov, Sergey

    2008-01-01

    A solitary wave, resembling a soliton wave, is observed when analyzing the linear problem of polarized shear (SH) surface acoustic waves propagating in elastic orthotropic two-layered traction-free plates. The analysis is performed by applying a special complex formalism and the Modified Transfer Matrix (MTM) method. Conditions for the existence of solitary SH waves are obtained. Analytical expressions for the phase speed of the solitary wave are derived. To cite this article: I. Djeran-Maigre, S. Kuznetsov, C. R. Mecanique 336 (2008).

  19. A 3D unstructured non-hydrostatic ocean model for internal waves

    NASA Astrophysics Data System (ADS)

    Ai, Congfang; Ding, Weiye

    2016-10-01

    A 3D non-hydrostatic model is developed to compute internal waves. A novel grid arrangement is incorporated in the model. This not only ensures the homogenous Dirichlet boundary condition for the non-hydrostatic pressure can be precisely and easily imposed but also renders the model relatively simple in its discretized form. The Perot scheme is employed to discretize horizontal advection terms in the horizontal momentum equations, which is based on staggered grids and has the conservative property. Based on previous water wave models, the main works of the present paper are to (1) utilize a semi-implicit, fractional step algorithm to solve the Navier-Stokes equations (NSE); (2) develop a second-order flux-limiter method satisfying the max-min property; (3) incorporate a density equation, which is solved by a high-resolution finite volume method ensuring mass conservation and max-min property based on a vertical boundary-fitted coordinate system; and (4) validate the developed model by using four tests including two internal seiche waves, lock-exchange flow, and internal solitary wave breaking. Comparisons of numerical results with analytical solutions or experimental data or other model results show reasonably good agreement, demonstrating the model's capability to resolve internal waves relating to complex non-hydrostatic phenomena.

  20. Impedance of pistons on a two-layer medium in a planar infinite rigid baffle.

    PubMed

    Hassan, Scott E

    2007-07-01

    An integral transform technique is used to develop a general solution for the impedance of rigid pistons acting on a two-layer medium. The medium consists of a semi-infinite acoustic fluid on a viscoelastic thick plate in a rigid infinite baffle. The stresses acting on the planar baffle, as a result of piston motion, are determined using theory of linear elasticity and are therefore unrestricted in terms of applicable frequency range. The special case of a circular piston is considered and expressions for the self-and mutual impedances are developed and evaluated numerically. Numerical results are compared with classical piston impedance functions and finite-element model results. At low frequencies (k(0)a<1), the self-impedances vary significantly from the classical piston impedance functions due to the shear properties of the viscoelastic medium. In the midfrequency range (1two-layer medium generally exhibit an increased decay, as a function of separation distance, over the classical results.

  1. One-dimensional seismic response of two-layer soil deposits with shear wave velocity inversion

    SciTech Connect

    Ding Yuqin; Pagliaroli, Alessandro; Lanzo, Giuseppe

    2008-07-08

    The paper presents the results of a parametric study with the purpose of investigating the 1D linear and equivalent linear seismic response of a 30 meters two-layer soil deposits characterized by a stiff layer overlying a soft layer. The thickness of the soft layer was assumed equal to 0.25, 0.5 and 0.75 H, being H the total thickness of the deposit. The shear wave velocity of the soft layer was assumed equal to V{sub s} = 90 and 180 m/s while for the stiff layer V{sub s} = 360, 500 and 700 m/s were considered. Six accelerograms extracted by an Italian database characterized by different predominant periods ranging from 0.1 to 0.7 s were used as input outcropping motion. For the equivalent liner analyses, the accelerograms were scaled at three different values of peak ground acceleration (PGA), namely 0.1, 0.3 and 0.5 g. The numerical results show that the two-layer ground motion is generally deamplified in terms of PGA with respect to the outcrop PGA. This reduction is mainly controlled by the shear wave velocity of the soft layer, being larger for lower V{sub s} values, by the amount of nonlinearity experienced by the soft soil during the seismic shaking and, to a minor extent, by the thickness of the soft soil layer.

  2. On-Line Thickness Measurement for Two-Layer Systems on Polymer Electronic Devices

    PubMed Central

    Grassi, Ana Perez; Tremmel, Anton J.; Koch, Alexander W.; El-Khozondar, Hala J.

    2013-01-01

    During the manufacturing of printed electronic circuits, different layers of coatings are applied successively on a substrate. The correct thickness of such layers is essential for guaranteeing the electronic behavior of the final product and must therefore be controlled thoroughly. This paper presents a model for measuring two-layer systems through thin film reflectometry (TFR). The model considers irregular interfaces and distortions introduced by the setup and the vertical vibration movements caused by the production process. The results show that the introduction of these latter variables is indispensable to obtain correct thickness values. The proposed approach is applied to a typical configuration of polymer electronics on transparent and non-transparent substrates. We compare our results to those obtained using a profilometer. The high degree of agreement between both measurements validates the model and suggests that the proposed measurement method can be used in industrial applications requiring fast and non-contact inspection of two-layer systems. Moreover, this approach can be used for other kinds of materials with known optical parameters. PMID:24253192

  3. Waves propagation in two-layer system over a non-rational submerged hump

    NASA Astrophysics Data System (ADS)

    Harun, Fatimah Noor

    2017-09-01

    Multiple layered ocean system is a field that is crucial to understand. It exist with the existing of the difference in sea temperature and salinity that will form a density layer in the ocean. This phenomena is crucial to understand and very significance especially to offshore company such as oil related industry and logistics for avoiding casualties at the workplace. Thus, in this paper, the different density of the ocean is focused by simplified the multilayer ocean into two-layer model with the existing of a submerged hump on the seabed. By using the two-layer shallow water waves equation, this problem is solved analytically. For the verification process, the new solution is compared with the existing solution, and the two model is hardly distinguishable Then, the effect of the density and hump profiles to the wave propagation and wave refraction and diffraction are analyzed. The hump and the density profiles have a very significance effect to the relative wave amplitude and wave refraction. The bigger α resulting in the higher relative amplitude and the denser fluid give the weaker relative wave amplitude because of the stronger restoring force.

  4. Two-layer wireless distributed sensor/control network based on RF

    NASA Astrophysics Data System (ADS)

    Feng, Li; Lin, Yuchi; Zhou, Jingjing; Dong, Guimei; Xia, Guisuo

    2006-11-01

    A project of embedded Wireless Distributed Sensor/Control Network (WDSCN) based on RF is presented after analyzing the disadvantages of traditional measure and control system. Because of high-cost and complexity, such wireless techniques as Bluetooth and WiFi can't meet the needs of WDSCN. The two-layer WDSCN is designed based on RF technique, which operates in the ISM free frequency channel with low power and high transmission speed. Also the network is low cost, portable and moveable, integrated with the technologies of computer network, sensor, microprocessor and wireless communications. The two-layer network topology is selected in the system; a simple but efficient self-organization net protocol is designed to fit the periodic data collection, event-driven and store-and-forward. Furthermore, adaptive frequency hopping technique is adopted for anti-jamming apparently. The problems about power reduction and synchronization of data in wireless system are solved efficiently. Based on the discussion above, a measure and control network is set up to control such typical instruments and sensors as temperature sensor and signal converter, collect data, and monitor environmental parameters around. This system works well in different rooms. Experiment results show that the system provides an efficient solution to WDSCN through wireless links, with high efficiency, low power, high stability, flexibility and wide working range.

  5. Two-Layer Tight Frame Sparsifying Model for Compressed Sensing Magnetic Resonance Imaging

    PubMed Central

    Peng, Xi; Dong, Pei

    2016-01-01

    Compressed sensing magnetic resonance imaging (CSMRI) employs image sparsity to reconstruct MR images from incoherently undersampled K-space data. Existing CSMRI approaches have exploited analysis transform, synthesis dictionary, and their variants to trigger image sparsity. Nevertheless, the accuracy, efficiency, or acceleration rate of existing CSMRI methods can still be improved due to either lack of adaptability, high complexity of the training, or insufficient sparsity promotion. To properly balance the three factors, this paper proposes a two-layer tight frame sparsifying (TRIMS) model for CSMRI by sparsifying the image with a product of a fixed tight frame and an adaptively learned tight frame. The two-layer sparsifying and adaptive learning nature of TRIMS has enabled accurate MR reconstruction from highly undersampled data with efficiency. To solve the reconstruction problem, a three-level Bregman numerical algorithm is developed. The proposed approach has been compared to three state-of-the-art methods over scanned physical phantom and in vivo MR datasets and encouraging performances have been achieved. PMID:27747226

  6. Evapotranspiration estimation using Landsat-8 data with a two-layer framework

    NASA Astrophysics Data System (ADS)

    Yin, Jian; Wang, Hailong; Zhan, Chesheng; Lu, Yang

    2017-01-01

    Evapotranspiration (ET) plays an important role in hydrological cycle by linking land surface and atmosphere through water and energy transfers. Based on the data from the Landsat-8 satellite for typical days with clear sky condition from 2013 to 2016, a two-layer daily ET remote sensing framework was built, which includes four compartments: surface feature parameter estimation, evaporative fraction estimation, daily net radiation estimation, and daily ET extension. Based on the model, evaporation, transpiration, and daily ET in Shahe River Basin were estimated. The estimated daily ET showed a mean absolute percentage error of 8.7% in the plain areas, and 12.1% in the mountainous areas, compared to observations using large aperture scintillometer and eddy covariance system. The method gave higher accuracy than other remote sensing models applied in the same area previously, including the surface energy balance system and the ETWatch. By analyzing the relationship between land use types and surface water/heat fluxes, it was found that the surface energy balance components in the basin have prominent spatial-temporal features, and the soil component's features are more obvious. It indicated that the proposed two-layer approach is superior to others in terms of simulation accuracy, and applicable to daily scale ET estimations on complex terrains.

  7. Validation of the Two-Layer Model for Correcting Clear Sky Reflectance Near Clouds

    NASA Technical Reports Server (NTRS)

    Wen, Guoyong; Marshak, Alexander; Evans, K. Frank; Vamal, Tamas

    2014-01-01

    A two-layer model was developed in our earlier studies to estimate the clear sky reflectance enhancement near clouds. This simple model accounts for the radiative interaction between boundary layer clouds and molecular layer above, the major contribution to the reflectance enhancement near clouds for short wavelengths. We use LES/SHDOM simulated 3D radiation fields to valid the two-layer model for reflectance enhancement at 0.47 micrometer. We find: (a) The simple model captures the viewing angle dependence of the reflectance enhancement near cloud, suggesting the physics of this model is correct; and (b) The magnitude of the 2-layer modeled enhancement agree reasonably well with the "truth" with some expected underestimation. We further extend our model to include cloud-surface interaction using the Poisson model for broken clouds. We found that including cloud-surface interaction improves the correction, though it can introduced some over corrections for large cloud albedo, large cloud optical depth, large cloud fraction, large cloud aspect ratio. This over correction can be reduced by excluding scenes (10 km x 10km) with large cloud fraction for which the Poisson model is not designed for. Further research is underway to account for the contribution of cloud-aerosol radiative interaction to the enhancement.

  8. Effects of heat treatment on Raman spectra of two-layer 12C/13C graphene.

    PubMed

    Kalbac, Martin; Frank, Otakar; Kavan, Ladislav

    2012-10-22

    The Raman spectra of two-layered graphene on a silicon substrate were studied in the temperature range from 298 to 1073 K in an inert atmosphere. Isotopic engineering was used to fabricate two-layer graphene specimens containing (13)C atoms in the top layer and (12)C atoms in the bottom layer, which allowed the behavior of each particular layer to be distinguished as a function of temperature. It is demonstrated that the top layer exhibits much lower Raman temperature coefficients than the bottom one for both the G and the G' modes. We suggest that the changes in the Raman spectra of graphene observed during thermal cycling are predominantly caused by a superposition of two effects, namely, the mechanical stress in graphene exerted by the substrate and the intrinsic changes in the graphene lattice caused by the temperature itself. The top graphene layer is proposed to be more relaxed than the bottom graphene layer and thus reflects almost exclusively the temperature variations as a freestanding graphene layer would.

  9. Faraday instability and nonlinear pattern formation of a two-layer system: A reduced model

    NASA Astrophysics Data System (ADS)

    Bestehorn, Michael; Pototsky, Andrey

    2016-10-01

    Stability and pattern formation of a two-layer liquid system with large aspect ratio subjected to vertical harmonic oscillations is studied by means of an integrated boundary layer model. The lower layer rests on an oscillating solid substrate, the upper layer is separated by a deformable interface from the lower layer and bounded at the top with a second, free interface to the ambient passive air. The model is derived from the Navier-Stokes equations in long-wave approximation, including inertial terms. Applying a Floquet analysis, linear stability charts and dispersion relations are computed and compared with results from the full linearized Navier-Stokes equations and the long-wave approximation. Nonlinear Faraday patterns simultaneously occurring at the interface and at the film surface are studied by numerically solving the integrated boundary layer model in two and three spatial dimensions. For gravitationally stable two-layer films with a lighter fluid on top of the heavier fluid, we find squares, hexagons, quasiperiodic patterns with eightfold symmetry as well as localized states in the form of large scale depletion regions or finite depth holes, occurring at the interface and surface. For a Rayleigh-Taylor unstable combination (heavier fluid above the light one) we show that external vibration increases the lifetime of the film by delaying or completely suppressing the film rupture.

  10. Reverse-feeding effect of epidemic by propagators in two-layered networks

    NASA Astrophysics Data System (ADS)

    Dayu, Wu; Yanping, Zhao; Muhua, Zheng; Jie, Zhou; Zonghua, Liu

    2016-02-01

    Epidemic spreading has been studied for a long time and is currently focused on the spreading of multiple pathogens, especially in multiplex networks. However, little attention has been paid to the case where the mutual influence between different pathogens comes from a fraction of epidemic propagators, such as bisexual people in two separated groups of heterosexual and homosexual people. We here study this topic by presenting a network model of two layers connected by impulsive links, in contrast to the persistent links in each layer. We let each layer have a distinct pathogen and their interactive infection is implemented by a fraction of propagators jumping between the corresponding pairs of nodes in the two layers. By this model we show that (i) the propagators take the key role to transmit pathogens from one layer to the other, which significantly influences the stabilized epidemics; (ii) the epidemic thresholds will be changed by the propagators; and (iii) a reverse-feeding effect can be expected when the infective rate is smaller than its threshold of isolated spreading. A theoretical analysis is presented to explain the numerical results. Project supported by the National Natural Science Foundation of China (Grant Nos. 11135001, 11375066, and 11405059) and the National Basic Key Program of China (Grant No. 2013CB834100).

  11. Gravity currents propagating up a slope in a two-layer fluid

    NASA Astrophysics Data System (ADS)

    Marleau, Larissa J.; Flynn, Morris R.; Sutherland, Bruce R.

    2015-03-01

    Gravity currents produced by partial-depth lock-release and travelling along the base of a two-layer stratified ambient are investigated as they propagate along a rising slope. The initial gravity current front speed is found to be consistent with a theory adapted from Shin et al. ["Gravity currents produced by lock exchange," J. Fluid Mech. 521, 1-34 (2004)] to the case of partial-depth currents in two-layer ambients. The subsequent evolution depends on the gravity current speed relative to the speed of the interfacial disturbance it creates. The deceleration of supercritical gravity currents, which travel faster than the interfacial disturbance, is gradual and agrees well with the relationship developed by Marleau et al. ["Gravity currents propagating up a slope," Phys. Fluids 26, 046605 (2014)] for upslope gravity currents in uniform density ambients. In several subcritical cases, the gravity current suddenly came to rest as a consequence of interactions with the interfacial disturbance. The disturbance amplitude, speed, and width are found to be nearly constant during its evolution. In cases for which the ambient interface intersected the bottom slope, the amplitude, speed, and width were nearly constant up to the point where the lower layer shallowed and the disturbance transformed into an upslope-propagating gravity current.

  12. TWO-LAYER MATHEMATICAL MODELING OF GENE EXPRESSION: INCORPORATING DNA-LEVEL INFORMATION AND SYSTEM DYNAMICS*

    PubMed Central

    DRESCH, JACQUELINE M.; THOMPSON, MARC A.; ARNOSTI, DAVID N.; CHIU, CHICHIA

    2014-01-01

    High-throughput genome sequencing and transcriptome analysis have provided researchers with a quantitative basis for detailed modeling of gene expression using a wide variety of mathematical models. Two of the most commonly employed approaches used to model eukaryotic gene regulation are systems of differential equations, which describe time-dependent interactions of gene networks, and thermodynamic equilibrium approaches that can explore DNA-level transcriptional regulation. To combine the strengths of these approaches, we have constructed a new two-layer mathematical model that provides a dynamical description of gene regulatory systems, using detailed DNA-based information, as well as spatial and temporal transcription factor concentration data. We also developed a semi-implicit numerical algorithm for solving the model equations and demonstrate here the efficiency of this algorithm through stability and convergence analyses. To test the model, we used it together with the semi-implicit algorithm to simulate a Drosophila gene regulatory circuit that drives development in the dorsal-ventral axis of the blastoderm-stage embryo, involving three genes. For model validation, we have done both mathematical and statistical comparisons between the experimental data and the model’s simulated data. Where protein and cis-regulatory information is available, our two-layer model provides a method for recapitulating and predicting dynamic aspects of eukaryotic transcriptional systems that will greatly improve our understanding of gene regulation at a global level. PMID:25328249

  13. TWO-LAYER MATHEMATICAL MODELING OF GENE EXPRESSION: INCORPORATING DNA-LEVEL INFORMATION AND SYSTEM DYNAMICS.

    PubMed

    Dresch, Jacqueline M; Thompson, Marc A; Arnosti, David N; Chiu, Chichia

    2013-03-01

    High-throughput genome sequencing and transcriptome analysis have provided researchers with a quantitative basis for detailed modeling of gene expression using a wide variety of mathematical models. Two of the most commonly employed approaches used to model eukaryotic gene regulation are systems of differential equations, which describe time-dependent interactions of gene networks, and thermodynamic equilibrium approaches that can explore DNA-level transcriptional regulation. To combine the strengths of these approaches, we have constructed a new two-layer mathematical model that provides a dynamical description of gene regulatory systems, using detailed DNA-based information, as well as spatial and temporal transcription factor concentration data. We also developed a semi-implicit numerical algorithm for solving the model equations and demonstrate here the efficiency of this algorithm through stability and convergence analyses. To test the model, we used it together with the semi-implicit algorithm to simulate a Drosophila gene regulatory circuit that drives development in the dorsal-ventral axis of the blastoderm-stage embryo, involving three genes. For model validation, we have done both mathematical and statistical comparisons between the experimental data and the model's simulated data. Where protein and cis-regulatory information is available, our two-layer model provides a method for recapitulating and predicting dynamic aspects of eukaryotic transcriptional systems that will greatly improve our understanding of gene regulation at a global level.

  14. Transient natural and surface-tension-driven convection in a two-layer gas-and-liquid enclosure with nonuniform radiative transfer

    NASA Technical Reports Server (NTRS)

    Abramzon, B.; Edwards, D. K.; Sirignano, W. A.

    1986-01-01

    A numerical study has been made of transient heat transfer and fluid flow in a cylindrical enclosure containing a two-layer gas-and-liquid system. The geometric configuration and the boundary conditions of the problem are relevant to the analysis of the preignition processes during the fire accident situation involving a pool of liquid fuel in the vicinity of an ignition source. It is demonstrated that the effects of the natural and thermocapillary convection, radiative transfer, thermal inertia and conduction of the walls bounding the enclosure, as well as, the magnitude of the gravity field play important roles in the development of the temperature and velocity fields in the container.

  15. Transient natural and surface-tension-driven convection in a two-layer gas-and-liquid enclosure with nonuniform radiative transfer

    NASA Technical Reports Server (NTRS)

    Abramzon, B.; Edwards, D. K.; Sirignano, W. A.

    1986-01-01

    A numerical study has been made of transient heat transfer and fluid flow in a cylindrical enclosure containing a two-layer gas-and-liquid system. The geometric configuration and the boundary conditions of the problem are relevant to the analysis of the preignition processes during the fire accident situation involving a pool of liquid fuel in the vicinity of an ignition source. It is demonstrated that the effects of the natural and thermocapillary convection, radiative transfer, thermal inertia and conduction of the walls bounding the enclosure, as well as, the magnitude of the gravity field play important roles in the development of the temperature and velocity fields in the container.

  16. The transition from hydrostatic to greater than hydrostatic fluid pressure in presently active continental hydrothermal systems in crystalline rock

    SciTech Connect

    Fournier, R.O. )

    1991-05-01

    Fluid flow at hydrostatic pressure (P{sub h}) is relatively common through fractures in silicic and in mafic crystalline rocks where temperatures are less than about 350-370C. In contrast, pore-fluid pressure (P{sub f}) > P{sub h} has been encountered at the bottom of 3 geothermal exploration wells that attained temperatures >370C (at Larderello, Italy, at Nesjavellir, Iceland, and at The Geysers, California). Chemical sealing by deposition of minerals in veins appears to have allowed the development of the high P{sub f} encountered in the above wells. The upper limit for the magnitude of P{sub f} that can be attained is controlled by either the onset of shear fracturing (where differential stress is relatively high) that reopens clogged veins, or the hydraulic opening of new or old fractures (at relatively low values of differential stress). The brittle-plastic transition for silicic rocks can occur at temperatures as high as 370-400C in tectonically active regions. In regions where high-temperature geothermal systems develop and persist, it appears that either strain rates commonly are in the range 10{sup {minus}12} to 10{sup {minus}13}, or that silicic rocks in the shallow crust generally behave rheologically more like wet quartz diorite than wet Westerly granite.

  17. Calculation of the outcomes of remodeling of arteries subjected to sustained hypertension using a 3D two-layered model.

    PubMed

    Rachev, Alexander; Taylor, W Robert; Vito, Raymond P

    2013-07-01

    Arteries manifest a remodeling response to long-term alterations in arterial pressure and blood flow by changing geometry, structure, and composition through processes driven by perturbations of the local stresses in the vascular wall from their baseline values. The objective of this study is twofold--to develop a general method for calculating the remodeling responses of an artery considered as a two-layered tube; and to provide results for adaptive and maladaptive remodeling of a coronary artery. By formulating an inverse problem of vascular mechanics, the geometrical dimensions and mechanical properties of an artery are calculated from a prescribed deformed configuration, stress field, structural stiffness, and applied load. As an illustrative example we consider a human LAD coronary artery in both a perfect and incomplete adaptive response to a sustained step-wise change in pressure and a maladaptive response due to impaired remodeling of adventitia. The results obtained show that adventitia plays an important role in vascular mechanics when an artery is subjected to high arterial pressure. In addition to its well-known short term function of preventing over-inflation of an artery, it seems reasonable to accept that the manner by which adventitia remodels in response to a chronic increase in pressure is essential for preserving normal arterial function or may lead to an increased risk of developing vascular disorders.

  18. A hydrostatic pressure-cycle energy harvester

    NASA Astrophysics Data System (ADS)

    Shafer, Michael W.; Hahn, Gregory; Morgan, Eric

    2015-04-01

    There have been a number of new applications for energy harvesting with the ever-decreasing power consumption of microelectronic devices. In this paper we explore a new area of marine animal energy harvesting for use in powering tags known as bio-loggers. These devices record data about the animal or its surroundings, but have always had limited deployment times due to battery depletion. Reduced solar irradiance below the water's surface provides the impetus to explore other energy harvesting concepts beyond solar power for use on marine animals. We review existing tag technologies in relation to this application, specifically relating to energy consumption. Additionally, we propose a new idea for energy harvesting, using hydrostatic pressure changes as a source for energy production. We present initial testing results of a bench-top model and show that the daily energy harvesting potential from this technology can meet or exceed that consumed by current marine bio-logging tags. The application of this concept in the arena of bio-logging technology could substantially increase bio-logger deployment lifetimes, allowing for longitudinal studies over the course of multiple breeding and/or migration cycles.

  19. SPR Hydrostatic Column Model Verification and Validation.

    SciTech Connect

    Bettin, Giorgia; Lord, David; Rudeen, David Keith

    2015-10-01

    A Hydrostatic Column Model (HCM) was developed to help differentiate between normal "tight" well behavior and small-leak behavior under nitrogen for testing the pressure integrity of crude oil storage wells at the U.S. Strategic Petroleum Reserve. This effort was motivated by steady, yet distinct, pressure behavior of a series of Big Hill caverns that have been placed under nitrogen for extended period of time. This report describes the HCM model, its functional requirements, the model structure and the verification and validation process. Different modes of operation are also described, which illustrate how the software can be used to model extended nitrogen monitoring and Mechanical Integrity Tests by predicting wellhead pressures along with nitrogen interface movements. Model verification has shown that the program runs correctly and it is implemented as intended. The cavern BH101 long term nitrogen test was used to validate the model which showed very good agreement with measured data. This supports the claim that the model is, in fact, capturing the relevant physical phenomena and can be used to make accurate predictions of both wellhead pressure and interface movements.

  20. Mechanical stability of iron under hydrostatic stresses

    NASA Astrophysics Data System (ADS)

    Mishra, K. L.; Thakur, O. P.; Thakur, K. P.

    1991-09-01

    A comprehensive investigation of the mechanics of iron subjected to arbitrary fluid pressure has been carried out. Apart from the classical elastic moduli ( k, μ, and μ') and conventional elastic moduli (Green and stretch moduli) computations are carried out for a family of generalised moduli of which the conventional moduli are just specific members. With the generalised moduli the mechanical stability of iron is investigated through Born criteria. It is found that classical stability, Green stability and stretch stability are all represented uniquely by the present generalised scheme. The definition of effective classical moduli under stresses enabled the amalgamation of the Born criteria of lattice stability into the single classical criteria of lattice stability of cubic crystal under hydrostatic loading environment. Computations are also carried out to investigate the coordinate and stress dependence of Young's modulus of elasticity, Poisson's ratio, mean velocity of elastic wave, and Debye temperature. Surprisingly, it is found that all these properties of solids play an important role in representing the mechanical stability of the solid. The path of uniaxial loading of iron is also investigated along with its internal energy variation on this path. This indicated the existance of stress-free fcc phase of iron on the path of uniaxial deformation at cell length a=3.6444 Å giving enthalpy of transformation (bcc→fcc) of 1.1 kJ/mol in good agreement with experimental results.

  1. Control of hydrostatic transmission wind turbine

    NASA Astrophysics Data System (ADS)

    Rajabhandharaks, Danop

    In this study, we proposed a control strategy for a wind turbine that employed a hydrostatic transmission system for transmitting power from the wind turbine rotor via a hydraulic transmission line to a ground level generator. Wind turbine power curve tracking was achieved by controlling the hydraulic pump displacement and, at the other end of the hydraulic line, the hydraulic motor displacement was controlled so that the overall transmission loss was minimized. Steady state response, dynamic response, and system stability were assessed. The maximum transmission efficiency obtained ranged from 79% to 84% at steady state when the proposed control strategy was implemented. The leakage and friction losses of the hydraulic components were the main factors that compromised the efficiency. The simulation results showed that the system was stable and had fast and well-damped transient response. Double wind turbine system sharing hydraulic pipes, a hydraulic motor, and a generator were also studied. The hydraulic pipe diameter used in the double-turbine system increased by 27% compared to the single-turbine system in order to make the transmission coefficient comparable between both systems. The simulation results suggested that the leakage losses were so significant that the efficiency of the system was worsened compared with the single-turbine system. Future studies of other behavioral aspects and practical issues such as fluid dynamics, structure strength, materials, and costs are needed.

  2. Template-directed preparation of two-layer porous NiO film via hydrothermal synthesis for lithium ion batteries

    SciTech Connect

    Chen, Z.; Xiao, A.; Chen, Y.; Zuo, C.; Zhou, S.; Li, L.

    2012-08-15

    Graphical abstract: A two-layer porous NiO film is prepared via hydrothermal synthesis method based on monolayer polystyrene sphere template and shows noticeable Li battery performance with good cycle life and high capacity. Highlights: ► Two-layer porous NiO film is prepared via monolayer polystyrene spheres template. ► NiO film with high capacity as anode material for lithium ion batteries. ► Two-layer porous structure is favorable for fast lithium ion and electron transfer. -- Abstract: A two-layer porous NiO film is prepared by hydrothermal synthesis method through self-assembled monolayer polystyrene spheres template. The substructure of the NiO film is composed of ordered close-packed hollow-sphere array and the superstructure is made up of randomly NiO nanoflakes. The electrochemical properties are measured by galvanostatic charge/discharge tests and cyclic voltammetric analysis (CV). As anode material for lithium ion batteries, the two-layer porous NiO film exhibits high initial coulombic efficiency of 75%, high reversible capacity and rather good cycling performance. The discharge capacity of the two-layer porous NiO film is 501 mAh g{sup −1} at 0.5 C after 50 cycles. The two-layer porous architecture is responsible for the enhancement of electrochemical properties.

  3. Two-layer thermal barrier coating for turbine airfoils - furnace and burner rig test results

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1976-01-01

    A simple, two-layer plasma-sprayed thermal barrier coating system was developed which has the potential for protecting high temperature air-cooled gas turbine components. Of those coatings initially examined, the most promising system consisted of a Ni-16Cr-6Al-0.6Y (in wt%) thermal barrier coating (about 0.005 to 0.010 cm thick) and a ZrO2-12Y2O3 (in wt%) thermal barrier coating (about 0.025 to 0.064 cm thick). This thermal barrier substantially lowered the metal temperature of an air-cooled airfoil. The coating withstood 3,200 cycles (80 sec at 1,280 C surface temperature) and 275 cycles (1 hr at 1,490 C surface temperature) without cracking or spalling. No separation of the thermal barrier from the bond coating or the bond coating from the substrate was observed.

  4. A Two-Layer Least Squares Support Vector Machine Approach to Credit Risk Assessment

    NASA Astrophysics Data System (ADS)

    Liu, Jingli; Li, Jianping; Xu, Weixuan; Shi, Yong

    Least squares support vector machine (LS-SVM) is a revised version of support vector machine (SVM) and has been proved to be a useful tool for pattern recognition. LS-SVM had excellent generalization performance and low computational cost. In this paper, we propose a new method called two-layer least squares support vector machine which combines kernel principle component analysis (KPCA) and linear programming form of least square support vector machine. With this method sparseness and robustness is obtained while solving large dimensional and large scale database. A U.S. commercial credit card database is used to test the efficiency of our method and the result proved to be a satisfactory one.

  5. Some considerations on numerical schemes for treating hyperbolicity issues in two-layer models

    NASA Astrophysics Data System (ADS)

    Sarno, L.; Carravetta, A.; Martino, R.; Papa, M. N.; Tai, Y.-C.

    2017-02-01

    Multi-layer depth-averaged models are widely employed in various hydraulic engineering applications. Yet, such models are not strictly hyperbolic. Their equation systems typically lose hyperbolicity when the relative velocities between layers become too large, which is associated with Kelvin-Helmholtz instabilities involving turbulent momentum exchanges between the layers. Focusing on the two-layer case, we present a numerical improvement that locally avoids the loss of hyperbolicity. The proposed modification introduces an additional momentum exchange between layers, whose value is iteratively calculated to be strictly sufficient to keep the system hyperbolic. The approach can be easily implemented in any finite volume scheme and there is no limitation concerning the density ratio between layers. Numerical examples, employing both HLL-type and Roe-type approximate Riemann solvers, are reported to validate the method and its key features.

  6. Synthesis of PVA/PVP hydrogels having two-layer by radiation and their physical properties

    NASA Astrophysics Data System (ADS)

    Park, Kyoung Ran; Nho, Young Chang

    2003-06-01

    In these studies, two-layer hydrogels which consisted of polyurethane membrane and a mixture of polyvinyl alcohol(PVA)/poly- N-vinylpyrrolidone(PVP)/glycerin/chitosan were made for the wound dressing. Polyurethane was dissolved in solvent, the polyurethane solution was poured on the mould, and then dried to make the thin membrane. Hydrophilic polymer solutions were poured on the polyurethane membranes, they were exposed to gamma irradiation or two steps of 'freezing and thawing' and gamma irradiation doses to make the hydrogels. The physical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the hydrogels for wound dressing. The physical properties of hydrogels such as gelation and gel strength was greatly improved when polyurethane membrane was used as a covering layer of hydrogel, and the evaporation speed of water in hydrogel was reduced.

  7. Calculation of AC loss in two-layer superconducting cable with equal currents in the layers

    NASA Astrophysics Data System (ADS)

    Erdogan, Muzaffer

    2016-12-01

    A new method for calculating AC loss of two-layer SC power transmission cables using the commercial software Comsol Multiphysics, relying on the approach of the equal partition of current between the layers is proposed. Applying the method to calculate the AC-loss in a cable composed of two coaxial cylindrical SC tubes, the results are in good agreement with the analytical ones of duoblock model. Applying the method to calculate the AC-losses of a cable composed of a cylindrical copper former, surrounded by two coaxial cylindrical layers of superconducting tapes embedded in an insulating medium with tape-on-tape and tape-on-gap configurations are compared. A good agreement between the duoblock model and the numerical results for the tape-on-gap cable is observed.

  8. Two-Layer Fragile Watermarking Method Secured with Chaotic Map for Authentication of Digital Holy Quran

    PubMed Central

    Khalil, Mohammed S.; Khan, Muhammad Khurram; Alginahi, Yasser M.

    2014-01-01

    This paper presents a novel watermarking method to facilitate the authentication and detection of the image forgery on the Quran images. Two layers of embedding scheme on wavelet and spatial domain are introduced to enhance the sensitivity of fragile watermarking and defend the attacks. Discrete wavelet transforms are applied to decompose the host image into wavelet prior to embedding the watermark in the wavelet domain. The watermarked wavelet coefficient is inverted back to spatial domain then the least significant bits is utilized to hide another watermark. A chaotic map is utilized to blur the watermark to make it secure against the local attack. The proposed method allows high watermark payloads, while preserving good image quality. Experiment results confirm that the proposed methods are fragile and have superior tampering detection even though the tampered area is very small. PMID:25028681

  9. Significance of thermal contact resistance in two-layer thermal-barrier-coated turbine vanes

    NASA Technical Reports Server (NTRS)

    Liebert, C. H.; Gaugler, R. E.

    1980-01-01

    The importance of thermal contact resistance between layers in heat transfer through two layer, plasma sprayed, thermal barrier coatings applied to turbine vanes was investigated. Results obtained with a system of NiCrAlY bond and yttria stabilized zirconia ceramic show that thermal contact resistance between layers is negligible. These results also verified other studies which showed that thermal contact resistance is negligible for a different coating system of NiCr bond calcia stabilized zirconia ceramic. The zirconia stabilized ceramic thermal conductivity data scatter presented in the literature is ?20 to -10 percent about a curve fit of the data. More accurate predictions of heat transfer and metal wall temperatures are obtained when the thermal conductivity values are used at the ?20 percent level.

  10. A two-layered classifier based on the radial basis function for the screening of thalassaemia.

    PubMed

    Masala, G L; Golosio, B; Cutzu, R; Pola, R

    2013-11-01

    The thalassaemias are blood disorders with hereditary transmission. Their distribution is global, with particular incidence in areas affected by malaria. Their diagnosis is mainly based on haematologic and genetic analyses. The aim of this study was to differentiate between persons with the thalassaemia trait and normal subjects by inspecting characteristics of haemochromocytometric data. The paper proposes an original method that is useful in screening activity for thalassaemia classification. A complete working system with a friendly graphical user interface is presented. A unique feature of the presented work is the adoption of a two-layered classification system based on Radial basis function, which improves the performance of the system. © 2013 Elsevier Ltd. All rights reserved.

  11. Development of analytical theory of the physical libration for a two-layer Moon

    NASA Astrophysics Data System (ADS)

    Petrova, Natalia; Barkin, Yurii; Gusev, Alexander; Ivanova, Tamara

    2010-05-01

    -project. Prognosis recommendations are made for the future experiment. The model of free rotation of the two-layer Moon is constructed, the periods of the free modes and of the librational motion of a pole are received, effects of influence of a lunar core on behavior of LPhL-harmonics caused by the solid-state rotation of the Moon are deduced. Computer simulating has revealed the sensitivity of the free libration periods to core's ellipticity and to core-mantle boundary dissipation parameters. Geometrical interpretation of the pole motion owing to the free libration is given. For the first time the theoretical model of tidal potential of the Moon is developed, on the basis of the model the analytical formulae for variations of the Stockes coefficients of the 2-nd order and of the speed of the Lunar rotation is received in dependence on time. For a two-layer structure of the Moon and the Mercury Cassini's law were stated at the first time: 1. a two-layer Moon keeps its own stationary rotation; 2. there is a splitting of Cassini nodes and angular momentums of Lunar mantle and core; 3. the same phenomenon will be observed for any two-layer planet (Mercury); 4. the differential rotation of a core and mantle is inherent to a planet as result of a generalized Cassini's Laws. Theoretical and practical methods of construction of the theory of rotation of the Earth have been successfully applied in the development of the theory of rotation of the Moon, in

  12. A Two-Layer Mathematical Modelling of Drug Delivery to Biological Tissues

    NASA Astrophysics Data System (ADS)

    Chakravarty, Koyel; Dalal, D. C.

    2016-10-01

    Local drug delivery has received much recognition in recent years, yet it is still unpredictable how drug efficacy depends on physicochemical properties and delivery kinetics. The purpose of the current study is to provide a useful mathematical model for drug release from a drug delivery device and consecutive drug transport in biological tissue, thereby aiding the development of new therapeutic drug by a systemic approach. In order to study the complete process, a two-layer spatio-temporal model depicting drug transport between the coupled media is presented. Drug release is described by considering solubilisation dynamics of drug particle, diffusion of the solubilised drug through porous matrix and also some other processes like reversible dissociation / recrystallization, drug particle-receptor binding and internalization phenomena. The model has led to a system of partial differential equations describing the important properties of drug kinetics. This model contributes towards the perception of the roles played by diffusion, mass-transfer, particle binding and internalization parameters.

  13. The fuzzy coat of pathological human Tau fibrils is a two-layered polyelectrolyte brush.

    PubMed

    Wegmann, Susanne; Medalsy, Izhar D; Mandelkow, Eckhard; Müller, Daniel J

    2013-01-22

    The structure and properties of amyloid-like Tau fibrils accumulating in neurodegenerative diseases have been debated for decades. Although the core of Tau fibrils assembles from short β-strands, the properties of the much longer unstructured Tau domains protruding from the fibril core remain largely obscure. Applying immunogold transmission EM, and force-volume atomic force microscopy (AFM), we imaged human Tau fibrils at high resolution and simultaneously mapped their mechanical and adhesive properties. Tau fibrils showed a ≈ 16-nm-thick fuzzy coat that resembles a two-layered polyelectrolyte brush, which is formed by the unstructured short C-terminal and long N-terminal Tau domains. The mechanical and adhesive properties of the fuzzy coat are modulated by electrolytes and pH, and thus by the cellular environment. These unique properties of the fuzzy coat help in understanding how Tau fibrils disturb cellular interactions and accumulate in neurofibrillary tangles.

  14. Two Layer Magnetodielectric Metamaterial with Enhanced Dielectric Constant as a New Ferrite Like Material

    NASA Astrophysics Data System (ADS)

    Zouganelis, Georgios; Rybin, Oleg

    2006-11-01

    In this study, we present large enhancement of effective dielectric constant of magnetodielectric metamaterials made from two layers of parallel periodic non-magnetized iron wires embedded inside dielectric (wax), in two orientations of them, relative to the incident electromagnetic field. This kind of enhancement is predicted by finite difference time domain (FDTD) method electromagnetic simulations made for infinite size metamaterials of same unit cell and same electromagnetic wave’s geometry of incidence. In this model, the complex internal constants were estimated from the calculated complex S-parameters by using Ross-Nicolson method. The validity of our prediction was tested, from comparison of calculated S-parameters with experimental ones measured on a sample made by rapid prototyping, using a modified strip transmission line method. The dielectric enhancement was found to be about 500%, as it was expected from simulations. Applicability of this family of metamaterials to ferrites like applications is discussed.

  15. 2-DE combined with two-layer feature selection accurately establishes the origin of oolong tea.

    PubMed

    Chien, Han-Ju; Chu, Yen-Wei; Chen, Chi-Wei; Juang, Yu-Min; Chien, Min-Wei; Liu, Chih-Wei; Wu, Chia-Chang; Tzen, Jason T C; Lai, Chien-Chen

    2016-11-15

    Taiwan is known for its high quality oolong tea. Because of high consumer demand, some tea manufactures mix lower quality leaves with genuine Taiwan oolong tea in order to increase profits. Robust scientific methods are, therefore, needed to verify the origin and quality of tea leaves. In this study, we investigated whether two-dimensional gel electrophoresis (2-DE) and nanoscale liquid chromatography/tandem mass spectroscopy (nano-LC/MS/MS) coupled with a two-layer feature selection mechanism comprising information gain attribute evaluation (IGAE) and support vector machine feature selection (SVM-FS) are useful in identifying characteristic proteins that can be used as markers of the original source of oolong tea. Samples in this study included oolong tea leaves from 23 different sources. We found that our method had an accuracy of 95.5% in correctly identifying the origin of the leaves. Overall, our method is a novel approach for determining the origin of oolong tea leaves.

  16. Study of electronic and optical properties of two-layered hydrogenated aluminum nitrate nanosheet

    NASA Astrophysics Data System (ADS)

    Faghihzadeh, Somayeh; Shahtahmasebi, Nasser; Rezaee Roknabadi, Mahmood

    2017-09-01

    First principle calculations based on density functional theory using GW approximation and two particle Bethe-Salpeter equation with electron-hole effect were performed to investigate electronic structure and optical properties of two-layered hydrogenated AlN. According to many body green function due to decrease in dimension and considering electron-electron effect, direct (indirect) band gap change from 2 (1.01) eV to 4.83 (3.62) eV. The first peak in imaginary part of dielectric function was observed in parallel direction to a plane obtaining 3.4 was achieved by bound exciton states possess 1.39 eV. The first absorption peak was seen in two parallel and perpendicular directions to a plane which are in UV region.

  17. On Two-Layer Hierarchical Networks How Does the Brain Do This?

    NASA Astrophysics Data System (ADS)

    Beiu, Valeriu; Madappuram, Basheer A. M.; Kelly, Peter M.; McDaid, Liam J.

    In this paper our aim is to identify layered hierarchical generic network topologies which could closely mimic brain’s connectivity. Recent analyses have compared the brain’s connectivity (based both on a cortical-equivalent Rent’s rule and on neurological data) with well-known network topologies used in supercomputers and massively parallel computers (using two different interpretations of Rent’s rule). These have revealed that none of the well-known computer network topologies by themselves are strong contenders for mimicking the brain’s connectivity. That is why in this paper we perform a high-level analysis of two-layer hierarchical generic networks. The range of granularities (i.e., number of gates/cores/neurons) as well as the fan-ins and the particular combinations of the two generic networks which would make such a mimicking achievable are identified and discussed.

  18. Electromagnetic wave scattering in a two-layer anisotropic random medium

    NASA Technical Reports Server (NTRS)

    Lee, J. K.; Kong, J. A.

    1985-01-01

    For electromagnetic wave propagation and scattering in an anisotropic random medium, the Dyson equation for the mean field and the Bethe-Salpeter equation for the correlation or the covariance of the field were derived. With the random permittivity expressed in a general anisotropic form, the bilocal and the nonlinear approximations are employed to solve the Dyson equation, and the ladder approximation to solve the Bethe-Salpeter equation. The mean dyadic Green's function for a two-layer anisotropic random medium with arbitrary three-dimensional correlation functions has been investigated with the zeroth-order solutions to the Dyson equation under the nonlinear approximation. The effective propagation constants are calculated for the four characteristic waves associated with the coherent vector fields, propagating in an anisotropic random-medium layer, which are the ordinary and extraordinary waves with upward- and downward-propagating vectors.

  19. Testing the Two-Layer Model for Correcting Clear Sky Reflectance near Clouds

    NASA Technical Reports Server (NTRS)

    Wen, Guoyong; Marshak, Alexander; Evans, Frank; Varnai, Tamas; Levy, Rob

    2015-01-01

    A two-layer model (2LM) was developed in our earlier studies to estimate the clear sky reflectance enhancement due to cloud-molecular radiative interaction at MODIS at 0.47 micrometers. Recently, we extended the model to include cloud-surface and cloud-aerosol radiative interactions. We use the LES/SHDOM simulated 3D true radiation fields to test the 2LM for reflectance enhancement at 0.47 micrometers. We find: The simple model captures the viewing angle dependence of the reflectance enhancement near cloud, suggesting the physics of this model is correct; the cloud-molecular interaction alone accounts for 70 percent of the enhancement; the cloud-surface interaction accounts for 16 percent of the enhancement; the cloud-aerosol interaction accounts for an additional 13 percent of the enhancement. We conclude that the 2LM is simple to apply and unbiased.

  20. Unidirectional invisibility in a two-layer non-PT-symmetric slab.

    PubMed

    Shen, Yun; Deng, Xiao Hua; Chen, Lin

    2014-08-11

    Recently, unidirectional invisibility has been demonstrated in parity-time (PT) symmetric periodic structures and has attracted great attention. Nevertheless, fabrication of a complex periodic structure may not be practically easy. In this paper, a simple two-layer non-PT-symmetric slab structure is proposed to realize unidirectional invisibility. We numerically show that in such conventional structure consisting of two slabs with different real parts of refractive indices, unidirectional invisibility can be achieved as proper imaginary parts of refractive indices and thicknesses of the slabs are satisfied. Moreover, the unidirectional invisibility can be converted to unidirectional reflection when the imaginary parts of the refractive indices are tuned to their odd symmetric forms.

  1. Wave turbulence in a two-layer fluid: Coupling between free surface and interface waves

    NASA Astrophysics Data System (ADS)

    Issenmann, Bruno; Laroche, Claude; Falcon, Eric

    2016-12-01

    We experimentally study gravity-capillary wave turbulence on the interface between two immiscible fluids of close density with free upper surface. We locally measure the wave height at the interface between both fluids by means of a highly sensitive laser Doppler vibrometer. We show that the inertial range of the capillary wave turbulence regime is significantly extended when the upper fluid depth is increased: The crossover frequency between the gravity and capillary wave turbulence regimes is found to decrease whereas the dissipative cut-off frequency of the spectrum is found to increase. We explain these observations by the progressive decoupling between waves propagating at the interface and the ones at the free surface, using the full dispersion relation of gravity-capillary waves in a two-layer fluid of finite depths. The cut-off evolution is due to the disappearance of parasitic capillaries responsible for the main wave dissipation for a single fluid.

  2. Charge-deposition in two-layer systems irradiated by electrons

    NASA Astrophysics Data System (ADS)

    Alouani-Bibi, F.; Lazurik, V. T.; Rogov, Yu. V.; Tabata, T.

    2001-02-01

    On the basis of the data obtained by computer simulation and theoretical analysis of the charge-deposition density in single slabs located in vacuum (Alouani-Bibi et al., 1999. Can. J. Phys. 77(2), 127-136), a semi-empirical model that describes the charge-deposition distributions in two-layer systems irradiated by fast electron beams has been developed. The slabs considered are made of materials with atomic numbers from 4 to 79 and thicknesses from 0.5 to 50 mg/cm 2 irradiated by electron beams with energies from 1 to 10 MeV. Comparisons have been made of the results obtained by the present model and those obtained by the PENELOPE code. Results of charge-deposition distributions for different material combinations of the layers are also presented.

  3. A uniqueness result for the inverse electromagnetic scattering problem in a two-layered medium

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodong; Zhang, Bo

    2010-10-01

    This paper is concerned with the inverse problem of scattering of time-harmonic electromagnetic waves by an impenetrable obstacle buried in the lower half-space of a two-layered background medium. We prove that the buried obstacle and its physical property can be uniquely determined from a knowledge of the tangential component of the electric field on some two-dimensional device in the upper half-space corresponding to all incident electric dipoles located on another two-dimensional device in the upper half-space with two different polarizations. The key ingredient of our proof is a novel reciprocity relation established in this paper for the solution of the scattering problem of the electric dipole located at two different source points.

  4. Seismic evidence of a two-layer lithospheric deformation in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Qin, Yanfang; Singh, Satish C.

    2015-09-01

    Intra-plate deformation and associated earthquakes are enigmatic features on the Earth. The Wharton Basin in the Indian Ocean is one of the most active intra-plate deformation zones, confirmed by the occurrence of the 2012 great earthquakes (Mw>=8.2). These earthquakes seem to have ruptured the whole lithosphere, but how this deformation is distributed at depth remains unknown. Here we present seismic reflection images that show faults down to 45 km depth. The amplitude of these reflections in the mantle first decreases with depth down to 25 km and then remains constant down to 45 km. The number of faults imaged along the profile and the number of earthquakes as a function of depth show a similar pattern, suggesting that the lithospheric mantle deformation can be divided into two layers: a highly fractured fluid-filled serpentinized upper layer and a pristine brittle lithospheric mantle where great earthquakes initiate and large stress drops occur.

  5. Novel criteria for the development of monotonic and oscillatory instabilities in a two-layer film

    NASA Astrophysics Data System (ADS)

    Nepomnyashchy, A. A.; Simanovskii, I. B.

    2017-09-01

    The development of the Marangoni instability in a two-layer film in the presence of a transverse temperature gradient and a heat source/sink at the liquid-liquid interface is investigated. The problem is solved by means of a linear stability theory and nonlinear simulations. Novel criteria for the development of monotonic and oscillatory instabilities have been formulated. It has been found that the nonlinear development of a monotonic instability leads to a rupture of the bottom layer or the top layer. Numerous types of nonlinear film evolution have been observed in the case of an oscillatory instability, among them alternating roll patterns of different scales and orientations, temporally non-periodic motions, and the rupture of either layer.

  6. Two-layer fragile watermarking method secured with chaotic map for authentication of digital Holy Quran.

    PubMed

    Khalil, Mohammed S; Kurniawan, Fajri; Khan, Muhammad Khurram; Alginahi, Yasser M

    2014-01-01

    This paper presents a novel watermarking method to facilitate the authentication and detection of the image forgery on the Quran images. Two layers of embedding scheme on wavelet and spatial domain are introduced to enhance the sensitivity of fragile watermarking and defend the attacks. Discrete wavelet transforms are applied to decompose the host image into wavelet prior to embedding the watermark in the wavelet domain. The watermarked wavelet coefficient is inverted back to spatial domain then the least significant bits is utilized to hide another watermark. A chaotic map is utilized to blur the watermark to make it secure against the local attack. The proposed method allows high watermark payloads, while preserving good image quality. Experiment results confirm that the proposed methods are fragile and have superior tampering detection even though the tampered area is very small.

  7. The effects of curvature and viscosity on baroclinic instability: A two-layer model

    NASA Technical Reports Server (NTRS)

    Fowlis, W. W.; Arias, S.

    1978-01-01

    A linear stability analysis of a baroclinic zonal current contained between two parallel rigid boundaries is presented. Curvature is included by performing the analysis on a beta b-plane and viscosity by allowing for the effects of Ekman layers on the rigid boundaries. A two-layer model is used. This calculation was carried out to assist in the design of a spherical model of the general circulation of the earth's atmosphere for Spacelab. In the low-gravity environment on an orbiting vehicle, a dominant radial dielectric body force, analogous to planetary gravity, can be achieved over a volume of liquid held between two concentric spheres. The results show the Eady short wavelength cutoff, and long wavelength cutoffs due to Ekman damping and curvature.

  8. Quantification of the specific yield in a two-layer hard-rock aquifer model

    NASA Astrophysics Data System (ADS)

    Durand, Véronique; Léonardi, Véronique; de Marsily, Ghislain; Lachassagne, Patrick

    2017-08-01

    Hard rock aquifers (HRA) have long been considered to be two-layer systems, with a mostly capacitive layer just below the surface, the saprolite layer, and a mainly transmissive layer underneath, the fractured layer. Although this hydrogeological conceptual model is widely accepted today within the scientific community, it is difficult to quantify the respective storage properties of each layer with an equivalent porous medium model. Based on an HRA field site, this paper attempts to quantify in a distinct manner the respective values of the specific yield (Sy) in the saprolite and the fractured layer, with the help of a deterministic hydrogeological model. The study site is the Plancoët migmatitic aquifer located in north-western Brittany, France, with piezometric data from 36 observation wells surveyed every two weeks for eight years. Whereas most of the piezometers (26) are located where the water table lies within the saprolite, thus representing the specific yield of the unconfined layer (Sy1), 10 of them are representative of the unconfined fractured layer (Sy2), due to their position where the saprolite is eroded or unsaturated. The two-layer model, based on field observations of the layer geometry, runs with the MODFLOW code. 81 values of the Sy1/Sy2 parameter sets were tested manually, as an inverse calibration was not able to calibrate these parameters. In order to calibrate the storage properties, a new quality-of-fit criterion called ;AdVar; was also developed, equal to the mean squared deviation of the seasonal piezometric amplitude variation. Contrary to the variance, AdVar is able to select the best values for the specific yield in each layer. It is demonstrated that the saprolite layer is about 2.5 times more capacitive than the fractured layer, with Sy1 = 10% (7% < Sy1 < 15%) against Sy2 = 2% (1% < Sy2 < 3%), in this particular example.

  9. Precession of a two-layer Earth: contributions of the core and elasticity

    NASA Astrophysics Data System (ADS)

    Baenas, Tomás; Ferrándiz, José M.; Escapa, Alberto; Getino, Juan; Navarro, Juan F.

    2016-04-01

    The Earth's internal structure contributes to the precession rate in a small but non-negligible amount, given the current accuracy goals demanded by IAG/GGOS to the reference frames, namely 30 μas and 3 μas/yr. These contributions come from a variety of sources. One of those not yet accounted for in current IAU models is associated to the crossed effects of certain nutation-rising terms of a two-layer Earth model; intuitively, it gathers an 'indirect' effect of the core via the NDFW, or FCN, resonance as well as a 'direct' effect arising from terms that account for energy variations depending on the elasticity of the core. Similar order of magnitude reaches the direct effect of the departure of the Earth's rheology from linear elasticity. To compute those effects we work out the problem in a unified way within the Hamiltonian framework developed by Getino and Ferrándiz (2001). It allows a consistent treatment of the problem since all the perturbations are derived from the same tide generating expansion and the crossing effects are rigorously obtained through Hori's canonical perturbation method. The problem admits an asymptotic analytical solution. The Hamiltonian is constructed by considering a two-layer Earth model made up of an anelastic mantle and a fluid core, perturbed by the gravitational action of the Moon and the Sun. The former effects reach some tens of μas/yr in the longitude rate, hence above the target accuracy level. We outline their influence in the estimation of the Earth's dynamical ellipticity, a main parameter factorizing both precession and nutation.

  10. Artery buckling analysis using a two-layered wall model with collagen dispersion.

    PubMed

    Mottahedi, Mohammad; Han, Hai-Chao

    2016-07-01

    Artery buckling has been proposed as a possible cause for artery tortuosity associated with various vascular diseases. Since microstructure of arterial wall changes with aging and diseases, it is essential to establish the relationship between microscopic wall structure and artery buckling behavior. The objective of this study was to developed arterial buckling equations to incorporate the two-layered wall structure with dispersed collagen fiber distribution. Seven porcine carotid arteries were tested for buckling to determine their critical buckling pressures at different axial stretch ratios. The mechanical properties of these intact arteries and their intima-media layer were determined via pressurized inflation test. Collagen alignment was measured from histological sections and modeled by a modified von-Mises distribution. Buckling equations were developed accordingly using microstructure-motivated strain energy function. Our results demonstrated that collagen fibers disperse around two mean orientations symmetrically to the circumferential direction (39.02°±3.04°) in the adventitia layer; while aligning closely in the circumferential direction (2.06°±3.88°) in the media layer. The microstructure based two-layered model with collagen fiber dispersion described the buckling behavior of arteries well with the model predicted critical pressures match well with the experimental measurement. Parametric studies showed that with increasing fiber dispersion parameter, the predicted critical buckling pressure increases. These results validate the microstructure-based model equations for artery buckling and set a base for further studies to predict the stability of arteries due to microstructural changes associated with vascular diseases and aging.

  11. Revisiting the Two-Layer Hypothesis: Coexistence of Alternative Functional Rooting Strategies in Savannas

    PubMed Central

    Holdo, Ricardo M.

    2013-01-01

    The two-layer hypothesis of tree-grass coexistence posits that trees and grasses differ in rooting depth, with grasses exploiting soil moisture in shallow layers while trees have exclusive access to deep water. The lack of clear differences in maximum rooting depth between these two functional groups, however, has caused this model to fall out of favor. The alternative model, the demographic bottleneck hypothesis, suggests that trees and grasses occupy overlapping rooting niches, and that stochastic events such as fires and droughts result in episodic tree mortality at various life stages, thus preventing trees from otherwise displacing grasses, at least in mesic savannas. Two potential problems with this view are: 1) we lack data on functional rooting profiles in trees and grasses, and these profiles are not necessarily reflected by differences in maximum or physical rooting depth, and 2) subtle, difficult-to-detect differences in rooting profiles between the two functional groups may be sufficient to result in coexistence in many situations. To tackle this question, I coupled a plant uptake model with a soil moisture dynamics model to explore the environmental conditions under which functional rooting profiles with equal rooting depth but different depth distributions (i.e., shapes) can coexist when competing for water. I show that, as long as rainfall inputs are stochastic, coexistence based on rooting differences is viable under a wide range of conditions, even when these differences are subtle. The results also indicate that coexistence mechanisms based on rooting niche differentiation are more viable under some climatic and edaphic conditions than others. This suggests that the two-layer model is both viable and stochastic in nature, and that a full understanding of tree-grass coexistence and dynamics may require incorporating fine-scale rooting differences between these functional groups and realistic stochastic climate drivers into future models. PMID

  12. Numerical simulation and analysis of complex patterns in a two-layer coupled reaction diffusion system

    NASA Astrophysics Data System (ADS)

    Li, Xin-Zheng; Bai, Zhan-Guo; Li, Yan; He, Ya-Feng; Zhao, Kun

    2015-04-01

    The resonance interaction between two modes is investigated using a two-layer coupled Brusselator model. When two different wavelength modes satisfy resonance conditions, new modes will appear, and a variety of superlattice patterns can be obtained in a short wavelength mode subsystem. We find that even though the wavenumbers of two Turing modes are fixed, the parameter changes have influences on wave intensity and pattern selection. When a hexagon pattern occurs in the short wavelength mode layer and a stripe pattern appears in the long wavelength mode layer, the Hopf instability may happen in a nonlinearly coupled model, and twinkling-eye hexagon and travelling hexagon patterns will be obtained. The symmetries of patterns resulting from the coupled modes may be different from those of their parents, such as the cluster hexagon pattern and square pattern. With the increase of perturbation and coupling intensity, the nonlinear system will convert between a static pattern and a dynamic pattern when the Turing instability and Hopf instability happen in the nonlinear system. Besides the wavenumber ratio and intensity ratio of the two different wavelength Turing modes, perturbation and coupling intensity play an important role in the pattern formation and selection. According to the simulation results, we find that two modes with different symmetries can also be in the spatial resonance under certain conditions, and complex patterns appear in the two-layer coupled reaction diffusion systems. Project supported by the National Natural Science Foundation of China (Grant No. 11247242), the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 51201057), and the Natural Science Foundation of Hebei Province, China (Grant No. A2014208171).

  13. Experimental study of two-layer thermal convection and implications for terrestrial systems.

    NASA Astrophysics Data System (ADS)

    Le Bars, M.; Davaille, A.

    2002-12-01

    Laboratory experiments have been performed to study two-layer thermal convection with interface deformations at large Rayleigh number (6.7x 103two layers invades the other. Severall successive pulsations can be observed for viscosity contrasts larger than one order of magnitude. Typical scales (time, length, temperature excess, velocity) and behaviours (direction of spouting, forms) are determined for each case. Both regimes are transient and systematically evolve towards one-layer Rayleigh-Bénard convection. However, heterogeneities are registered during very long times compared to typical time-scales of thermal convection. Mechanisms described in our experimental study could thus be of fundamental importance in some terrestrial planets: they could provide a dynamical explanation for periodic geologic events (especially enhanced volcanism) in Mars, Venus and Earth. Moreover, a deep 'primitive' region in the Earth's mantle, gravitationally stabilized by a small density contrast, could develop isopicnic oscillatory doming: the two reservoirs would then remain separated for billions of years, without preventing slab penetration.

  14. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Specific Heat of a Two-Layer Magnetic Superlattice

    NASA Astrophysics Data System (ADS)

    Qui, Rong-Ke; Liang, Jing; Zhao, Jian; Ying, Cai-Hong

    2009-11-01

    The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one are studied. It is found that the spin quantum numbers, the interlayer and intralayer exchange couplings, the anisotropy, the applied magnetic field, and the temperature all affect the specific heat of these superlattices. For both the ferromagnetic and ferrimagnetic superlattices, the specific heat decreases with increasing the spin quantum number, the absolute value of interlayer exchange coupling, intralayer exchange coupling, and anisotropy, while it increases with increasing temperature at low temperatures. When an applied magnetic field is enhanced, the specific heat decreases in the two-layer ferromagnetic superlattice, while it is almost unchanged in the two-layer ferrimagnetic superlattice at low field range at low temperatures.

  15. Single- and Two-Layer Coatings of Metal Blends onto Carbon Steel: Mechanical, Wear, and Friction Characterizations

    NASA Astrophysics Data System (ADS)

    Yilbas, Bekir Sami; Kumar, Aditya; Bhushan, Bharat

    2014-01-01

    Single- and two-layer coatings were deposited onto carbon steel using a high-velocity oxy-fuel deposition gun. The two-layer coating consisted of a top layer of tungsten carbide cobalt/nickel alloy blend that provides wear resistance and a bottom layer of iron/molybdenum blend that provides corrosion resistance. The morphological changes in the single- and two-layer coatings were examined using scanning electron microscopy. The residual stresses formed on the surface of various coatings were determined from x-ray diffraction data. Nanomechanical properties were measured using the nanoindentation technique. Microhardness and fracture toughness were measured incorporating the microindentation tests. Macrowear and macrofriction characteristics were measured using the pin-on-disk testing apparatus. The goal of this study was to ensure that the mechanical properties, friction, and wear resistance of the two-layer coating are similar to that of the single-layer coating.

  16. Hydrostatic pressure mimics gravitational pressure in characean cells

    NASA Technical Reports Server (NTRS)

    Staves, M. P.; Wayne, R.; Leopold, A. C.

    1992-01-01

    Hydrostatic pressure applied to one end of a horizontal Chara cell induces a polarity of cytoplasmic streaming, thus mimicking the effect of gravity. A positive hydrostatic pressure induces a more rapid streaming away from the applied pressure and a slower streaming toward the applied pressure. In contrast, a negative pressure induces a more rapid streaming toward and a slower streaming away from the applied pressure. Both the hydrostatic pressure-induced and gravity-induced polarity of cytoplasmic streaming respond identically to cell ligation, UV microbeam irradiation, external Ca2+ concentrations, osmotic pressure, neutral red, TEA Cl-, and the Ca2+ channel blockers nifedipine and LaCl3. In addition, hydrostatic pressure applied to the bottom of a vertically-oriented cell can abolish and even reverse the gravity-induced polarity of cytoplasmic streaming. These data indicate that both gravity and hydrostatic pressure act at the same point of the signal transduction chain leading to the induction of a polarity of cytoplasmic streaming and support the hypothesis that characean cells respond to gravity by sensing a gravity-induced pressure differential between the cell ends.

  17. Hydrostatic pressure mimics gravitational pressure in characean cells

    NASA Technical Reports Server (NTRS)

    Staves, M. P.; Wayne, R.; Leopold, A. C.

    1992-01-01

    Hydrostatic pressure applied to one end of a horizontal Chara cell induces a polarity of cytoplasmic streaming, thus mimicking the effect of gravity. A positive hydrostatic pressure induces a more rapid streaming away from the applied pressure and a slower streaming toward the applied pressure. In contrast, a negative pressure induces a more rapid streaming toward and a slower streaming away from the applied pressure. Both the hydrostatic pressure-induced and gravity-induced polarity of cytoplasmic streaming respond identically to cell ligation, UV microbeam irradiation, external Ca2+ concentrations, osmotic pressure, neutral red, TEA Cl-, and the Ca2+ channel blockers nifedipine and LaCl3. In addition, hydrostatic pressure applied to the bottom of a vertically-oriented cell can abolish and even reverse the gravity-induced polarity of cytoplasmic streaming. These data indicate that both gravity and hydrostatic pressure act at the same point of the signal transduction chain leading to the induction of a polarity of cytoplasmic streaming and support the hypothesis that characean cells respond to gravity by sensing a gravity-induced pressure differential between the cell ends.

  18. Hydrostatic Stress Effect on the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2003-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

  19. Hydrostatic Stress Effect on the Yield Behavior of Inconel 100

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.; Wilson, Christopher D.

    2003-01-01

    Classical metal plasticity theory assumes that hydrostatic stress has negligible effect on the yield and postyield behavior of metals. Recent reexaminations of classical theory have revealed a significant effect of hydrostatic stress on the yield behavior of various geometries. Fatigue tests and nonlinear finite element analyses (FEA) of Inconel 100 (IN100) equal-arm bend specimens and new monotonic tests and nonlinear finite element analyses of IN100 smooth tension, smooth compression, and double-edge notch tension (DENT) test specimens have revealed the effect of internal hydrostatic tensile stresses on yielding. Nonlinear FEA using the von Mises (yielding is independent of hydrostatic stress) and the Drucker-Prager (yielding is linearly dependent on hydrostatic stress) yield functions were performed. A new FEA constitutive model was developed that incorporates a pressure-dependent yield function with combined multilinear kinematic and multilinear isotropic hardening using the ABAQUS user subroutine (UMAT) utility. In all monotonic tensile test cases, the von Mises constitutive model, overestimated the load for a given displacement or strain. Considering the failure displacements or strains for the DENT specimen, the Drucker-Prager FEM s predicted loads that were approximately 3% lower than the von Mises values. For the failure loads, the Drucker Prager FEM s predicted strains that were up to 35% greater than the von Mises values. Both the Drucker-Prager model and the von Mises model performed equally-well in simulating the equal-arm bend fatigue test.

  20. Storage capacity and learning algorithms for two-layer neural networks

    NASA Astrophysics Data System (ADS)

    Engel, A.; Köhler, H. M.; Tschepke, F.; Vollmayr, H.; Zippelius, A.

    1992-05-01

    A two-layer feedforward network of McCulloch-Pitts neurons with N inputs and K hidden units is analyzed for N-->∞ and K finite with respect to its ability to implement p=αN random input-output relations. Special emphasis is put on the case where all hidden units are coupled to the output with the same strength (committee machine) and the receptive fields of the hidden units either enclose all input units (fully connected) or are nonoverlapping (tree structure). The storage capacity is determined generalizing Gardner's treatment [J. Phys. A 21, 257 (1988); Europhys. Lett. 4, 481 (1987)] of the single-layer perceptron. For the treelike architecture, a replica-symmetric calculation yields αc~ √K for a large number K of hidden units. This result violates an upper bound derived by Mitchison and Durbin [Biol. Cybern. 60, 345 (1989)]. One-step replica-symmetry breaking gives lower values of αc. In the fully connected committee machine there are in general correlations among different hidden units. As the limit of capacity is approached, the hidden units are anticorrelated: One hidden unit attempts to learn those patterns which have not been learned by the others. These correlations decrease as 1/K, so that for K-->∞ the capacity per synapse is the same as for the tree architecture, whereas for small K we find a considerable enhancement for the storage per synapse. Numerical simulations were performed to explicitly construct solutions for the tree as well as the fully connected architecture. A learning algorithm is suggested. It is based on the least-action algorithm, which is modified to take advantage of the two-layer structure. The numerical simulations yield capacities p that are slightly more than twice the number of degrees of freedom, while the fully connected net can store relatively more patterns than the tree. Various generalizations are discussed. Variable weights from hidden to output give the same results for the storage capacity as does the committee

  1. Optical measurements of absorption changes in two-layered diffusive media

    NASA Astrophysics Data System (ADS)

    Fabbri, Francesco; Sassaroli, Angelo; Henry, Michael E.; Fantini, Sergio

    2004-04-01

    We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is ~0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of ~4% for the superficial layer and ~10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers.

  2. Hydrostatic Water Level Systems At Homestake DUSEL

    NASA Astrophysics Data System (ADS)

    Stetler, L. D.; Volk, J. T.

    2009-12-01

    Two arrays of Fermilab-style hydrostatic water level sensors have been installed in the former Homestake gold mine in Lead, SD, the site of the new Deep Underground Science and Engineering Laboratory (DUSEL). Sensors were constructed at Fermilab from 8.5 cm diameter PVC pipe (housing) that was sealed on the ends and fit with a proximity sensor. The instrument have a height of 10 cm. Two ports in each sensor housing provide for connectivity, the upper port for air and the bottom port for water. Multiple instruments connected in series provide a precise water level and differences in readings between successive sensors provide for ground tilt to be resolved. Sensor resolution is 5 μm per count and has a range of approximately 1.25 cm. Data output from each sensor is relayed to a Fermilab-constructed readout card that also has temperature/relative humidity and barometric pressure sensors connected. All data are relayed out of the mine by fiber optic cable and can be recorded by Ethernet at remote locations. The current arrays have been installed on the 2000-ft level (610 m) and consist of six instruments in each array. Three sensors were placed in a N-S oriented drift and three in an E-W oriented drift. Using this orientation, it is anticipated that tilt direction may be resolved in addition to overall tilt magnitude. To date the data show passage of earth tides and frequency analysis has revealed five components to this signal, three associated with the semi-diurnal (~12.4 hr) and two with the diurnal (~24.9 hr) tides. Currently, installation methods are being analyzed between concrete pillar and rib-mounting using the existing setup on the 2000-ft level. Using these results, two additional arrays of Fermilab instruments will be installed on the 4550-ft and 4850-ft levels (1387 and 1478 m, respectively). In addition to Fermilab instruments, several high resolution Budker tiltmeters (1 μm resolution) will be installed in the mine workings in the near future, some

  3. Hydrostatic Microextrusion of Steel and Copper

    NASA Astrophysics Data System (ADS)

    Berti, Guido; Monti, Manuel; D'Angelo, Luciano

    2011-05-01

    The paper presents an experimental investigation based on hydrostatic micro extrusion of billets in low carbon steel and commercially pure copper, and the relevant results. The starting billets have a diameter of 0.3 mm and are 5 mm long; a high pressure generator consisting of a manually operated piston screw pump is used to pressurize the fluid up to 4200 bar, the screw pump is connected through a 3-way distribution block to the extrusion die and to a strain gauge high pressure sensor. The sensor has a full scale of 5000 bar and the extrusion pressure is acquired at a sampling rate of 2 kHz by means of an acquisition program written in the LabVIEW environment. Tests have been conducted at room temperature and a lubricant for wire drawing (Chemetall Gardolube DO 338) acts both as the pressurizing fluid and lubricant too. In addition, billets were graphite coated. Different fluid pressures and process durations have been adopted, resulting in different extrusion lengths. The required extrusion pressure is much higher than in non-micro forming operations (this effect is more evident for steel). On the cross section of the extruded parts, hardness and grain size distribution have been measured, the former through Vickers micro hardness (10 g load) tests. In the case of the extrusion of copper, the material behaves as in microdrawing process. In the case of the extrusion of steel, the hardness increases from the core to the surface as in the drawing process, but with lower values. The analysis evidenced the presence of the external layer, but its thickness is about 1/3 of the external layer in the drawn wire and the grains appear smaller than in the layer of the drawn wire. The extruding force required along the extruding direction is higher (22-24 N) than the drawing force along the same direction (12 N): being the material, the reduction ratio, the die sliding length the same in both cases, the higher extrusion force should be caused by a higher tangential friction

  4. Hydrostatic Microextrusion of Steel and Copper

    SciTech Connect

    Berti, Guido; Monti, Manuel; D'Angelo, Luciano

    2011-05-04

    The paper presents an experimental investigation based on hydrostatic micro extrusion of billets in low carbon steel and commercially pure copper, and the relevant results. The starting billets have a diameter of 0.3 mm and are 5 mm long; a high pressure generator consisting of a manually operated piston screw pump is used to pressurize the fluid up to 4200 bar, the screw pump is connected through a 3-way distribution block to the extrusion die and to a strain gauge high pressure sensor. The sensor has a full scale of 5000 bar and the extrusion pressure is acquired at a sampling rate of 2 kHz by means of an acquisition program written in the LabVIEW environment. Tests have been conducted at room temperature and a lubricant for wire drawing (Chemetall Gardolube DO 338) acts both as the pressurizing fluid and lubricant too. In addition, billets were graphite coated. Different fluid pressures and process durations have been adopted, resulting in different extrusion lengths. The required extrusion pressure is much higher than in non-micro forming operations (this effect is more evident for steel). On the cross section of the extruded parts, hardness and grain size distribution have been measured, the former through Vickers micro hardness (10 g load) tests. In the case of the extrusion of copper, the material behaves as in microdrawing process. In the case of the extrusion of steel, the hardness increases from the core to the surface as in the drawing process, but with lower values. The analysis evidenced the presence of the external layer, but its thickness is about 1/3 of the external layer in the drawn wire and the grains appear smaller than in the layer of the drawn wire. The extruding force required along the extruding direction is higher (22-24 N) than the drawing force along the same direction (12 N): being the material, the reduction ratio, the die sliding length the same in both cases, the higher extrusion force should be caused by a higher tangential friction

  5. Some two-layer models of the shelf-slope front: Geostropic adjustment and its maintenence

    SciTech Connect

    Ou, H.W.

    1983-10-01

    Two conceptual models of a two-layered frontal system are presented to study the wintertime shelf-slope front. The first model examines the geostropic adjustment over a step topography after the fall overturning and applied only over short time scales before the nonconservative processes become important. The second model, on the other hand, examines the thermodynamic balance over longer time scales when some dissipative and mixing effects are included. From the geostropic-adjustment model, it is found that the flat-bottom solution of a less-dense shelf water with respect to the slope water is little modified by the presence of a step. But in the case of denser shelf water, the solution shows the detachment of a spillage when the depth ratio across the step is greater than two-resembling some regional observations. In the frictional model, the wind generted entrainment is demonstrated to provide a virtual momentum source to maintain the along-front current shear against friction and thus can account for the persistence of the front through the winter season. The entrainment also decreases the bouyancy of the exported shelf water, the distribution of which however, varies greatly with the external parameters. For parameter values applicable to the Middle Atlantic Bight, an inflection point, corresponding to a weakened lateral bouyance gradient, is predicted above the front, consistent with observation.

  6. A Novel Approach to ECG Classification Based upon Two-Layered HMMs in Body Sensor Networks

    PubMed Central

    Liang, Wei; Zhang, Yinlong; Tan, Jindong; Li, Yang

    2014-01-01

    This paper presents a novel approach to ECG signal filtering and classification. Unlike the traditional techniques which aim at collecting and processing the ECG signals with the patient being still, lying in bed in hospitals, our proposed algorithm is intentionally designed for monitoring and classifying the patient's ECG signals in the free-living environment. The patients are equipped with wearable ambulatory devices the whole day, which facilitates the real-time heart attack detection. In ECG preprocessing, an integral-coefficient-band-stop (ICBS) filter is applied, which omits time-consuming floating-point computations. In addition, two-layered Hidden Markov Models (HMMs) are applied to achieve ECG feature extraction and classification. The periodic ECG waveforms are segmented into ISO intervals, P subwave, QRS complex and T subwave respectively in the first HMM layer where expert-annotation assisted Baum-Welch algorithm is utilized in HMM modeling. Then the corresponding interval features are selected and applied to categorize the ECG into normal type or abnormal type (PVC, APC) in the second HMM layer. For verifying the effectiveness of our algorithm on abnormal signal detection, we have developed an ECG body sensor network (BSN) platform, whereby real-time ECG signals are collected, transmitted, displayed and the corresponding classification outcomes are deduced and shown on the BSN screen. PMID:24681668

  7. Powerful Amplification Cascades of FRET-Based Two-Layer Nonenzymatic Nucleic Acid Circuits.

    PubMed

    Quan, Ke; Huang, Jin; Yang, Xiaohai; Yang, Yanjing; Ying, Le; Wang, He; Xie, Nuli; Ou, Min; Wang, Kemin

    2016-06-07

    Nucleic acid circuits have played important roles in biological engineering and have increasingly attracted researchers' attention. They are primarily based on nucleic acid hybridizations and strand displacement reactions between nucleic acid probes of different lengths. Signal amplification schemes that do not rely on protein enzyme show great potential in analytical applications. While the single amplification circuit often achieves linear amplification that may not meet the need for detection of target in a very small amount, it is very necessary to construct cascade circuits that allow for larger amplification of inputs. Herein, we have successfully engineered powerful amplification cascades of FRET-based two-layer nonenzymatic nucleic acid circuits, in which the outputs of catalyzed hairpin assembly (CHA) activate hybridization chain reactions (HCR) circuits to induce repeated hybridization, allowing real-time monitoring of self-assembly process by FRET signal. The cascades can yield 50000-fold signal amplification with the help of the well-designed and high-quality nucleic acid circuit amplifiers. Subsequently, with coupling of structure-switching aptamer, as low as 200 pM adenosine is detected in buffer, as well as in human serum. To our knowledge, we have for the first time realized real-time monitoring adaptation of HCR to CHA circuits and achieved amplified detection of nucleic acids and small molecules with relatively high sensitivity.

  8. Hemoglobin oxygenation of a two-layer tissue-simulating phantom from time-resolved reflectance

    NASA Astrophysics Data System (ADS)

    Hunter, Robert John

    2002-04-01

    A dual wavelength time-resolved reflectance system was developed for monitoring hemoglobin saturation noninvasively. The ability of the system to determine the optical properties of tissue-simulating phantoms was examined. To quantify the accuracy of the technique in monitoring hemoglobin saturation, measurements were performed in a homogeneous phantom containing human erythrocytes in a scattering solution. The hemoglobin saturation of this phantom could be controlled and monitored with an alternate technique. After system validation in this simple model, a more realistic, two-layer phantom model was investigated. The top layer was chosen to simulate either skin or fat and the oxygenation of the bottom layer, which corresponded to muscle, was controlled. The thickness of the fat layer was varied from 1.5 to 10 mm to investigate the effects of increasing the top layer thickness. Time-resolved measurements of reflectance, performed through the top layer were analyzed with a simple homogeneous diffusion model to quantify the hemoglobin saturation of the bottom layer. These data were compared with simultaneous measurements of oxygenation made directly in the bottom layer. Errors in estimating hemoglobin saturation with this method ranged from 5--11% depending on top layer thickness. Preliminary in vivo measurements were also undertaken which demonstrated promising results, although no comparative technique was used in these studies.

  9. Melanoma thickness measurement in two-layer tissue phantoms using pulsed photothermal radiometry (PPTR)

    NASA Astrophysics Data System (ADS)

    Wang, Tianyi; Qiu, Jinze; Paranjape, Amit; Milner, Thomas E.

    2009-02-01

    Melanoma is a malignant tumor of melanocytes which are found predominantly in skin. Melanoma is one of the rarer types of skin cancer but causes the majority of skin cancer related deaths. The staging of malignant melanoma using Breslow thickness is important because of the relationship to survival rate after five years. Pulsed photothermal radiometry (PPTR) is based on the time-resolved acquisition of infrared (IR) emission from a sample after pulsed laser exposure. PPTR can be used to investigate the relationship between melanoma thickness and detected radiometric temperature using two-layer tissue phantoms. We used a Monte Carlo simulation to mimic light transport in melanoma and employed a three-dimensional heat transfer model to obtain simulated radiometric temperature increase and, in comparison, we also conducted PPTR experiments to confirm our simulation results. Simulation and experimental results show similar trends: thicker absorbing layers corresponding to deeper lesions produce slower radiometric temperature decays. A quantitative relationship exists between PPTR radiometric temperature decay time and thickness of the absorbing layer in tissue phantoms.

  10. Deposition, Heat Treatment And Characterization of Two Layer Bioactive Coatings on Cylindrical PEEK

    PubMed Central

    Durham, John W.; Rabiei, Afsaneh

    2015-01-01

    Polyether ether ketone (PEEK) rods were coated via ion beam asssited deposition (IBAD) at room temperature. The coating consists of a two-layer design of yttria-stabilized zirconia (YSZ) as a heat-protection layer, and hydroxyapatite (HA) as a top layer to increase bioactivity. A rotating substrate holder was designed to deposit an even coating on the cylindrical surface of PEEK rods; the uniformity is verified by cross-sectional measurements using scanning electron microscopy (SEM). Deposition is followed by heat treatment of the coating using microwave annealing and autoclaving. Transmission electron microscopy (TEM) showed a dense, uniform columnar grain structure in the YSZ layer that is well bonded to the PEEK substrate, while the calcium phosphate layer was amorphous and pore-free in its as-deposited state. Subsequent heat treatment via microwave energy introduced HA crystallization in the calcium phosphate layer and additional autoclaving further expanded the crystallization of the HA layer. Chemical composition evaluation of the coating indicated the Ca/P ratios of the HA layer to be near that of stoichiometric HA, with minor variations through the HA layer thickness. The adhesion strength of as-deposited HA/YSZ coatings on smooth, polished PEEK surfaces was mostly unaffected by microwave heat treatment, but decreased with additional autoclave treatment. Increasing surface roughness showed improvement of bond strength. PMID:27713592

  11. A two-layer recurrent neural network for nonsmooth convex optimization problems.

    PubMed

    Qin, Sitian; Xue, Xiaoping

    2015-06-01

    In this paper, a two-layer recurrent neural network is proposed to solve the nonsmooth convex optimization problem subject to convex inequality and linear equality constraints. Compared with existing neural network models, the proposed neural network has a low model complexity and avoids penalty parameters. It is proved that from any initial point, the state of the proposed neural network reaches the equality feasible region in finite time and stays there thereafter. Moreover, the state is unique if the initial point lies in the equality feasible region. The equilibrium point set of the proposed neural network is proved to be equivalent to the Karush-Kuhn-Tucker optimality set of the original optimization problem. It is further proved that the equilibrium point of the proposed neural network is stable in the sense of Lyapunov. Moreover, from any initial point, the state is proved to be convergent to an equilibrium point of the proposed neural network. Finally, as applications, the proposed neural network is used to solve nonlinear convex programming with linear constraints and L1 -norm minimization problems.

  12. A novel approach to ECG classification based upon two-layered HMMs in body sensor networks.

    PubMed

    Liang, Wei; Zhang, Yinlong; Tan, Jindong; Li, Yang

    2014-03-27

    This paper presents a novel approach to ECG signal filtering and classification. Unlike the traditional techniques which aim at collecting and processing the ECG signals with the patient being still, lying in bed in hospitals, our proposed algorithm is intentionally designed for monitoring and classifying the patient's ECG signals in the free-living environment. The patients are equipped with wearable ambulatory devices the whole day, which facilitates the real-time heart attack detection. In ECG preprocessing, an integral-coefficient-band-stop (ICBS) filter is applied, which omits time-consuming floating-point computations. In addition, two-layered Hidden Markov Models (HMMs) are applied to achieve ECG feature extraction and classification. The periodic ECG waveforms are segmented into ISO intervals, P subwave, QRS complex and T subwave respectively in the first HMM layer where expert-annotation assisted Baum-Welch algorithm is utilized in HMM modeling. Then the corresponding interval features are selected and applied to categorize the ECG into normal type or abnormal type (PVC, APC) in the second HMM layer. For verifying the effectiveness of our algorithm on abnormal signal detection, we have developed an ECG body sensor network (BSN) platform, whereby real-time ECG signals are collected, transmitted, displayed and the corresponding classification outcomes are deduced and shown on the BSN screen.

  13. A laboratory study on migration of K+ in a two-layer landfill liner system.

    PubMed

    Du, Yan Jun; Hayashi, Shigenori

    2005-10-01

    Contaminant transport through the clay liner and the underIying secondary leachate drain layer (SLDL) in landfills was studied through a laboratory test, and analysis method on the transport of K+ in a two-layer soil system. The soils used for this study were Ariake clay and the underlying layer, Shirasu soil from the Kyushu region of Japan, representing the clay liner material and SLDL material, respectively. The effective diffusion coefficients (De) of the selected target chemical species, potassium (K+) for the Ariake clay and Shirasu soil were back-calculated using a computer program, and it was found that values of De derived from this study were consistent with those previously published. The hypothesis that the mechanical dispersion process can be negligible has been proved to be reasonable based on both the observation that the predicted values fit the experimental data and the analyses of two dimensionless parameters. Parametric analysis showed the transport of K+ through the soils is controlled by advection-diffusion rather than diffusion only, whereas at low Darcy velocity (i.e. < or = 10(-9) m s(-1)), transport of K+ would be controlled by diffusion. The test results and parametric analysis may be applied in design of landfill liners and SLDLs, particularly in coastal areas.

  14. Non-rigid Contributions to the Precession Rate of a Two-layers Earth Model

    NASA Astrophysics Data System (ADS)

    Ferrandiz, J. M.; Escapa, A.; Baenas, T.; Getino, J.; Navarro, J. F.

    2015-12-01

    The Earth's internal structure contributes to the precession rate in a non-negligible way considering current accuracies. These contributions come from a variety of sources, the most important being associated to the crossing effects of nutational terms and to the departures of the Earth rheology with respect to a perfect elastic model. To compute them we work out this problem in a unified way within the Hamiltonian framework developed in Getino and Ferrándiz (2001). It allows a consistent treatment of these effects, since all the perturbations are derived from the same tide generating expansion and the crossing effects are rigorously obtained through Hori's canonical perturbation method. These analytical expressions are constructed by considering a two layer Earth model made up of an anelastic mantle and a fluid core, perturbed by the gravitational action of the Moon and the Sun. We discuss the origin and the magnitude of the different terms and determine their influence in the value of the Earth's dynamical ellipticity, as well as the related indirect effects on the nutation series.

  15. Species production and heat release rates in two-layered natural gas fires

    SciTech Connect

    Zukoski, E.E.; Morehart, J.H.; Kubota, T.; Toner, S.J. )

    1991-02-01

    A fire burning in an enclosure with restricted ventilation will result in the accumulation of a layer of warm products of combustion mixed with entrained air adjacent to the ceiling. For many conditions, the depth of this layer will extend to occupy a significant fraction of the volume of the room. Eventually, the interface between this vitiated ceiling layer and the uncontaminated environment below will position itself so that a large portion of the combustion processes occur in this vitiated layer. A description is given of experimental work concerning the rates of formation of product species and heat release in a turbulent, buoyant natural gas diffusion flame burning in this two-layered configuration. The enclosure was modeled by placing a hood above a burner so that it accumulated the plume gases, and the unsteady development of the ceiling layer was modeled by the direct addition of air into the upper portion of the hood. Measurements of the composition of these gases allowed the computation of stoichiometries and heat release rates. These investigations showed that the species produced in the flame depend primarily on the stoichiometry of the gases present in the ceiling layer and weakly on the temperature of the layer, but are independent of the fuel pair ratio of the mass transported into the layer by the plume. Heat release rates in the fires were compared to a theoretical limit based on a stoichiometric reaction of fuel and air with excess components left unchanged by the combustion.

  16. Chemical control of hydrodynamic instabilities in partially miscible two-layer systems

    NASA Astrophysics Data System (ADS)

    de Wit, A.; Riolfo, L. A.; Lemaigre, L.; Rossi, F.; Rustici, M.; Budroni, M. A.

    2013-11-01

    Hydrodynamic instabilities at the interface between two partially miscible liquids impact numerous applications including sequestration of supercritical liquid CO2 in old petroleum reservoirs or saline aquifers. As an alternative to difficult in situ studies of the related mixing dynamics, we introduce a new laboratory-scale model system on which buoyancy- and Marangoni-driven convective instabilities of partially miscible two-layer systems can easily be studied and controlled in presence or not of chemical reactions. This system consists in the stratification of a pure ester on top of a denser partially miscible aqueous solution in the gravitational field. The rich convective dynamics observed upon partial dissolution of the ester in the water followed by its hydrolysis highlight the specificity of partially miscible systems as compared to fully miscible or immiscible ones, i.e. the possibility to control the convective pattern and the mixing properties by tuning (i) the intrinsic miscibility of the ester in water, (ii) the feedback of the dissolved species on its own miscibility as well as (iii) the composition and reactivity of the aqueous solution with the ester phase.

  17. A Two-Layer Method for Sedentary Behaviors Classification Using Smartphone and Bluetooth Beacons.

    PubMed

    Cerón, Jesús D; López, Diego M; Hofmann, Christian

    2017-01-01

    Among the factors that outline the health of populations, person's lifestyle is the more important one. This work focuses on the caracterization and prevention of sedentary lifestyles. A sedentary behavior is defined as "any waking behavior characterized by an energy expenditure of 1.5 METs (Metabolic Equivalent) or less while in a sitting or reclining posture". To propose a method for sedentary behaviors classification using a smartphone and Bluetooth beacons considering different types of classification models: personal, hybrid or impersonal. Following the CRISP-DM methodology, a method based on a two-layer approach for the classification of sedentary behaviors is proposed. Using data collected from a smartphones' accelerometer, gyroscope and barometer; the first layer classifies between performing a sedentary behavior and not. The second layer of the method classifies the specific sedentary activity performed using only the smartphone's accelerometer and barometer data, but adding indoor location data, using Bluetooth Low Energy (BLE) beacons. To improve the precision of the classification, both layers implemented the Random Forest algorithm and the personal model. This study presents the first available method for the automatic classification of specific sedentary behaviors. The layered classification approach has the potential to improve processing, memory and energy consumption of mobile devices and wearables used.

  18. Novel two-layered zeolite NaA-silicalite-1 membranes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiongfu; Liu, Haiou; Yeung, King Lun

    2005-06-01

    A two-layered zeolite NaA-silicalite-1 membrane has been successfully prepared on a porous α-alumina tube by using seeded hydrothermal synthesis. The procedure involves pre-seeding with nanosized seed and subsequent regrowth by hydrothermal treatment. Single-layered NaA and silicalite-1 membranes were also synthesized for comparison. The membrane was composed of a silicalite-1 layer on top and a NaA layer on the porous support. SEM results of the membrane indicate that both the silicalite-1 layer and the NaA layer are uniform and well-intergrown. The silicalite-1 and NaA layers in the ‘sandwich’ mode have similar thickness of 3-4 μm, whereas the thickness of their respective seed layer is different. The NaA seed layer is much thicker than the silicalite-1seed layer. This may be attributed to the different capillary action on the support and NaA layer during using a slip-casting seeding method. XRD analysis has also proved both zeolite NaA and zeolite silicalite-1 layers coexist in the dual-layered membrane. This method is also suitable for preparing other multi-layer zeolite membranes.

  19. Two-layer symbolic representation for stochastic models with phase-type distributed events

    NASA Astrophysics Data System (ADS)

    Longo, Francesco; Scarpa, Marco

    2015-07-01

    Among the techniques that have been proposed for the analysis of non-Markovian models, the state space expansion approach showed great flexibility in terms of modelling capacities.The principal drawback is the explosion of the state space. This paper proposes a two-layer symbolic method for efficiently storing the expanded reachability graph of a non-Markovian model in the case in which continuous phase-type distributions are associated with the firing times of system events, and different memory policies are considered. At the lower layer, the reachability graph is symbolically represented in the form of a set of Kronecker matrices, while, at the higher layer, all the information needed to correctly manage event memory is stored in a multi-terminal multi-valued decision diagram. Such an information is collected by applying a symbolic algorithm, which is based on a couple of theorems. The efficiency of the proposed approach, in terms of memory occupation and execution time, is shown by applying it to a set of non-Markovian stochastic Petri nets and comparing it with a classical explicit expansion algorithm. Moreover, a comparison with a classical symbolic approach is performed whenever possible.

  20. Diurnal cycles of evaporation using a two-layer hydrological model

    NASA Astrophysics Data System (ADS)

    Lakshmi, Venkataraman; Wood, Eric F.

    1998-01-01

    The objective of this paper is to study the variation of evaporation in time and space. A two-layer model for solving energy and water balance is presented. The vertical soil column between the soil surface and the water table is divided into the root zone and the transmission zone. The variable infiltration capacity (VIC) concept is used to introduce a spatially varied distribution of soil moisture in the root zone layer. The soil moisture is distributed uniformly in space in the transmission zone layer. The model is used to simulate the fluxes for the King's Creek catchment in Manhattan, Kansas for a period between June through October 1987 (for the four intensive field campaigns), during which the first ISLSCP (International Satelite Land Surface Climatology Project) field experiment (FIFE) was conducted. The model is calibrated using the observed data during the first intensive field campaign (IFC) and validated over the next three IFCS. The energy and water balance equations are solved to vield the time series of fluxes which are compared to their observed counterparts. The model predicted diurnal variation of the evaporative fluxes and the variation of the fluxes after rainfall events is compared with the observations. The model computed fluxes match fairly well with the observed fluxes.

  1. Thermal properties of composite two-layer systems with a fractal inclusion structure

    NASA Astrophysics Data System (ADS)

    Reyes-Salgado, J. J.; Dossetti, V.; Bonilla-Capilla, B.; Carrillo, J. L.

    2015-01-01

    In this work, we study the thermal transport properties of platelike composite two-layer samples made of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy and thermal relaxation, their effective thermal diffusivity and conductivity were experimentally measured. The composite layers were prepared under the action of a static magnetic field, resulting in anisotropic (fractal) inclusion structures with the formation of chain-like magnetite aggregates parallel to the faces of the layers. In one kind of the bilayers, a composite layer was formed on top of a resin layer while their relative thickness was varied. These samples can be described by known models. In contrast, bilayers with the same concentration of inclusions and the same thickness on both sides, where only the angle between their inclusion structures was systematically varied, show a nontrivial behaviour of their thermal conductivity as a function of this angle. Through a multifractal and lacunarity analysis, we explain the observed thermal response in terms of the complexity of the interface between the layers.

  2. Seismic evidence of a two-layer lithospheric deformation in the Indian Ocean.

    PubMed

    Qin, Yanfang; Singh, Satish C

    2015-09-14

    Intra-plate deformation and associated earthquakes are enigmatic features on the Earth. The Wharton Basin in the Indian Ocean is one of the most active intra-plate deformation zones, confirmed by the occurrence of the 2012 great earthquakes (Mw≥8.2). These earthquakes seem to have ruptured the whole lithosphere, but how this deformation is distributed at depth remains unknown. Here we present seismic reflection images that show faults down to 45 km depth. The amplitude of these reflections in the mantle first decreases with depth down to 25 km and then remains constant down to 45 km. The number of faults imaged along the profile and the number of earthquakes as a function of depth show a similar pattern, suggesting that the lithospheric mantle deformation can be divided into two layers: a highly fractured fluid-filled serpentinized upper layer and a pristine brittle lithospheric mantle where great earthquakes initiate and large stress drops occur.

  3. A finite difference analysis of the field present behind an acoustically impenetrable two-layer barrier.

    PubMed

    Hurrell, Andrew M

    2008-06-01

    The interaction of an incident sound wave with an acoustically impenetrable two-layer barrier is considered. Of particular interest is the presence of several acoustic wave components in the shadow region of this barrier. A finite difference model capable of simulating this geometry is validated by comparison to the analytical solution for an idealized, hard-soft barrier. A panel comprising a high air-content closed cell foam backed with an elastic (metal) back plate is then examined. The insertion loss of this panel was found to exceed the dynamic range of the measurement system and was thus acoustically impenetrable. Experimental results from such a panel are shown to contain artifacts not present in the diffraction solution, when acoustic waves are incident upon the soft surface. A finite difference analysis of this experimental configuration replicates the presence of the additional field components. Furthermore, the simulated results allow the additional components to be identified as arising from the S(0) and A(0) Lamb modes traveling in the elastic plate. These Lamb mode artifacts are not found to be present in the shadow region when the acoustic waves are incident upon the elastic surface.

  4. Study on electromagnetic propagation characteristics of two-layer media with CST software

    NASA Astrophysics Data System (ADS)

    Cao, Tengda; An, Chengquan; Tian, Yanhui

    2017-08-01

    This investigation is concerned with the simulation of the electromagnetic field produced by a horizontal electric dipole with the electromagnetic simulation software CST. It is easy but important to prove the validity of the CST modeling and simulation method to study the electromagnetic propagation characteristics by comparing the simulation results of CST with the theoretical mathematical model of unlimited single seawater. And then based on the modeling and simulation method of CST, a study on the differences of electromagnetic field propagation characteristics between which is in single seawater and which is in air-sea or sea-seabed two-layer media. The most important difference between the two kinds of models is that the electromagnetic propagation distance is much further in air-sea than single seawater, and that is because there exists a lateral propagation path in air-sea model. The further of the horizontal distance between the source and point of observation, the more important role the lateral path play. There are similar characteristics in sea-seabed model.

  5. Experimental study of migration of potassium ion through a two-layer soil system

    NASA Astrophysics Data System (ADS)

    Du, Yan Jun; Hayashi, Shigenori; Liu, Song Yu

    2005-10-01

    A barrier system based on the hydraulic trap design concept for a landfill was proposed. To study the field scenario in which a clay liner is underlain by a granular layer functioning as a secondary leachate drain layer, a laboratory advection-diffusion test was performed to investigate factors controlling the transport of contaminants in a two-layer soil system. The soils used for this study were Ariake clay and, the underlying layer, Shirasu soil from the Kyushu region of Japan. Potassium (K+) was selected as the target chemical species with an initial concentration of 905 mg L-1. The effective diffusion coefficients ( D e) of K+ for Ariake clay and Shirasu soil were back-calculated using an available computer program, Pollute V 6.3. Values of D e derived from this experiment are consistent with previously published ones. The Ariake clay has lower D e than the Shirasu soil. The hypothesis that mechanical dispersion can be considered negligible is reasonable based on both the observation that the predicted values well fit the experimental data and the analyses of two dimensionless parameters. Parametric analyses show that transport of K+ through soils is controlled by advection-diffusion rather than diffusion only, whereas at low Darcy velocity (i.e., ≤10-9 m s-1), transport of K+ will be controlled by diffusion. Applications of the test results and parametric analysis results in practical situations were reviewed.

  6. Inferring topologies via driving-based generalized synchronization of two-layer networks

    NASA Astrophysics Data System (ADS)

    Wang, Yingfei; Wu, Xiaoqun; Feng, Hui; Lu, Jun-an; Xu, Yuhua

    2016-05-01

    The interaction topology among the constituents of a complex network plays a crucial role in the network’s evolutionary mechanisms and functional behaviors. However, some network topologies are usually unknown or uncertain. Meanwhile, coupling delays are ubiquitous in various man-made and natural networks. Hence, it is necessary to gain knowledge of the whole or partial topology of a complex dynamical network by taking into consideration communication delay. In this paper, topology identification of complex dynamical networks is investigated via generalized synchronization of a two-layer network. Particularly, based on the LaSalle-type invariance principle of stochastic differential delay equations, an adaptive control technique is proposed by constructing an auxiliary layer and designing proper control input and updating laws so that the unknown topology can be recovered upon successful generalized synchronization. Numerical simulations are provided to illustrate the effectiveness of the proposed method. The technique provides a certain theoretical basis for topology inference of complex networks. In particular, when the considered network is composed of systems with high-dimension or complicated dynamics, a simpler response layer can be constructed, which is conducive to circuit design. Moreover, it is practical to take into consideration perturbations caused by control input. Finally, the method is applicable to infer topology of a subnetwork embedded within a complex system and locate hidden sources. We hope the results can provide basic insight into further research endeavors on understanding practical and economical topology inference of networks.

  7. Deposition, Heat Treatment And Characterization of Two Layer Bioactive Coatings on Cylindrical PEEK.

    PubMed

    Durham, John W; Rabiei, Afsaneh

    2016-09-15

    Polyether ether ketone (PEEK) rods were coated via ion beam asssited deposition (IBAD) at room temperature. The coating consists of a two-layer design of yttria-stabilized zirconia (YSZ) as a heat-protection layer, and hydroxyapatite (HA) as a top layer to increase bioactivity. A rotating substrate holder was designed to deposit an even coating on the cylindrical surface of PEEK rods; the uniformity is verified by cross-sectional measurements using scanning electron microscopy (SEM). Deposition is followed by heat treatment of the coating using microwave annealing and autoclaving. Transmission electron microscopy (TEM) showed a dense, uniform columnar grain structure in the YSZ layer that is well bonded to the PEEK substrate, while the calcium phosphate layer was amorphous and pore-free in its as-deposited state. Subsequent heat treatment via microwave energy introduced HA crystallization in the calcium phosphate layer and additional autoclaving further expanded the crystallization of the HA layer. Chemical composition evaluation of the coating indicated the Ca/P ratios of the HA layer to be near that of stoichiometric HA, with minor variations through the HA layer thickness. The adhesion strength of as-deposited HA/YSZ coatings on smooth, polished PEEK surfaces was mostly unaffected by microwave heat treatment, but decreased with additional autoclave treatment. Increasing surface roughness showed improvement of bond strength.

  8. A hydrostatic stress-dependent anisotropic model of viscoplasticity

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.; Tao, Q.; Verrilli, M. J.

    1994-01-01

    A hydrostatic stress-dependent, anisotropic model of viscoplasticity is formulated as an extension of Bodner's model. This represents a further extension of the isotropic Bodner model over that made to anisotropy by Robinson and MitiKavuma. Account is made of the inelastic deformation that can occur in metallic composites under hydrostatic stress. A procedure for determining the material parameters is identified that is virtually identical to the established characterization procedure for the original Bodner model. Characterization can be achieved using longitudinal/transverse tensile and shear tests and hydrostatic stress tests; alternatively, four off-axis tensile tests can be used. Conditions for a yield stress minimum under off-axis tension are discussed. The model is applied to a W/Cu composite; characterization is made using off-axis tensile data generated at NASA Lewis Research Center (LeRC).

  9. Further improvement of hydrostatic pressure sample injection for microchip electrophoresis.

    PubMed

    Luo, Yong; Zhang, Qingquan; Qin, Jianhua; Lin, Bingcheng

    2007-12-01

    Hydrostatic pressure sample injection method is able to minimize the number of electrodes needed for a microchip electrophoresis process; however, it neither can be applied for electrophoretic DNA sizing, nor can be implemented on the widely used single-cross microchip. This paper presents an injector design that makes the hydrostatic pressure sample injection method suitable for DNA sizing. By introducing an assistant channel into the normal double-cross injector, a rugged DNA sample plug suitable for sizing can be successfully formed within the cross area during the sample loading. This paper also demonstrates that the hydrostatic pressure sample injection can be performed in the single-cross microchip by controlling the radial position of the detection point in the separation channel. Rhodamine 123 and its derivative as model sample were successfully separated.

  10. Hydrostaticity of Pressure Media in Diamond Anvil Cells

    NASA Astrophysics Data System (ADS)

    You, Shu-Jie; Chen, Liang-Chen; Jin, Chang-Qing

    2009-09-01

    Hydrostaticity under high pressure of several materials from solid, fluid to gas, which are widely used as pressure media in modern high-pressure experiments, is investigated in diamond anvil cells. Judging from the R-line widths and R1 - R2 peak separation of Ruby fluorescence, the inert argon gas is hydrostatic up to about 30 GPa. The behavior of silicon oil is found to be similar to argon at pressures less than 10 GPa, while the widening of R-lines and increase of R1 - R2 peak separation at higher pressure loads indicate a significant degradation of hydrostaticity. Therefore silicon oil is considered as a good pressure medium at pressures less than 10 GPa but poor at higher pressures.

  11. Dynamic force response of spherical hydrostatic journal bearing for cryogenic applications

    NASA Technical Reports Server (NTRS)

    Sanandres, Luis

    1994-01-01

    Hydrostatic Journal Bearings (HJB's) are reliable and resilient fluid film rotor support elements ideal to replace roller bearings in cryogenic turbomachinery. HJB' will be used for primary space-power applications due to their long lifetime, low friction and wear, large load capacity, large direct stiffness, and damping force coefficients. An analysis for the performance characteristics of turbulent flow, orifice compensated, spherical hydrostatic journal bearings (HJB's) is presented. Spherical bearings allow tolerance for shaft misalignment without force performance degradation and have also the ability to support axial loads. The spherical HJB combines these advantages to provide a bearing design which could be used efficiently on high performance turbomachinery. The motion of a barotropic liquid on the thin film bearing lands is described by bulk-flow mass and momentum equations. These equations are solved numerically using an efficient CFD method. Numerical predictions of load capacity and force coefficients for a 6 recess, spherical HJB in a LO2 environment are presented. Fluid film axial forces and force coefficients of a magnitude about 20% of the radial load capacity are predicted for the case analyzed. Fluid inertia effects, advective and centrifugal, are found to affect greatly the static and dynamic force performance of the bearing studied.

  12. Influence of boundary conditions and turntable speeds on the stability of hydrostatic oil cavity

    NASA Astrophysics Data System (ADS)

    Liu, Zhaomiao; Zhang, Chengyin; Shen, Feng

    2011-09-01

    The flow, bearing, and carrying capacity of the cycloidal hydrostatic oil cavity in hydrostatic turntable systems are numerically simulated, considering the rotation speeds of a turntable from 0 to 5 m/s and different boundary conditions. The vortex effect is weakened, and the stability of the oil cavity is enhanced with the increase in lubricant viscosity. However, the increase in inlet speed, depth, and inlet radius of the oil cavity causes the vortex effect to increase and the stability of oil cavity to reduce. With the increase in the oil film thickness, the carrying capacity of the oil cavity diminishes. The oil cavity pressure increases along the direction of the motion of the turntable; it is distributed unevenly because of the rotation of the turntable. With the increase in turntable speed, the location and size of the vortex scope in the oil cavity flow field and the strength of the vortex near the entrance gradually weaken and move away from the entry. The distribution of pressure is determined by the locations of the vortex. When the vortex is close to the wall, the wall pressure increases at its location. Otherwise, the wall pressure decreases first and then increases after the center of the vortex.

  13. Accurate pressure gradient calculations in hydrostatic atmospheric models

    NASA Technical Reports Server (NTRS)

    Carroll, John J.; Mendez-Nunez, Luis R.; Tanrikulu, Saffet

    1987-01-01

    A method for the accurate calculation of the horizontal pressure gradient acceleration in hydrostatic atmospheric models is presented which is especially useful in situations where the isothermal surfaces are not parallel to the vertical coordinate surfaces. The present method is shown to be exact if the potential temperature lapse rate is constant between the vertical pressure integration limits. The technique is applied to both the integration of the hydrostatic equation and the computation of the slope correction term in the horizontal pressure gradient. A fixed vertical grid and a dynamic grid defined by the significant levels in the vertical temperature distribution are employed.

  14. A model for hydrostatic consolidation of Pierre shale

    USGS Publications Warehouse

    Savage, W.Z.; Braddock, W.A.

    1991-01-01

    This paper presents closed-form solutions for consolidation of transversely isotropic porous media under hydrostatic stress. The solutions are applied to model the time variation of pore pressure, volume strain and strains parallel and normal to bedding, and to obtain coefficients of consolidation and permeability, as well as other properties, and the bulk modulus resulting from hydrostatic consolidation of Pierre shale. It is found that the coefficients consolidation and permeability decrease and the bulk moduli increase with increasing confining pressure, reflecting the closure of voids in the rock. ?? 1991.

  15. Dependences of optical properties of spherical two-layered nanoparticles on parameters of gold core and material shell

    NASA Astrophysics Data System (ADS)

    Pustovalov, V. K.; Astafyeva, L. G.; Zharov, V. P.

    2013-12-01

    Modeling of nonlinear dependences of optical properties of spherical two-layered gold core and some material shell nanoparticles (NPs) placed in water on parameters of core and shell was carried out on the basis of the extended Mie theory. Efficiency cross-sections of absorption, scattering and extinction of radiation with wavelength 532 nm by core-shell NPs in the ranges of core radii r00=5-40 nm and of relative NP radii r1/r00=1-8 were calculated (r1-radius of two-layered nanoparticle). Shell materials were used with optical indexes in the ranges of refraction n1=0.2-1.5 and absorption k1=0-3.5 for the presentation of optical properties of wide classes of shell materials (including dielectrics, metals, polymers, vapor shell around gold core). Results show nonlinear dependences of optical properties of two-layered NPs on optical indexes of shell material, core r00 and relative NP r1/r00 radii. Regions with sharp decrease and increase of absorption, scattering and extinction efficiency cross-sections with changing of core and shell parameters were investigated. These dependences should be taken into account for applications of two-layered NPs in laser nanomedicine and optical diagnostics of tissues. The results can be used for experimental investigation of shell formation on NP core and optical determination of geometrical parameters of core and shell of two-layered NPs.

  16. An Implementation of Hydrostatic Boundary Conditions for Variable Density Lattice Boltzmann Methods

    NASA Astrophysics Data System (ADS)

    Bardsley, K. J.; Thorne, D. T.; Lee, J. S.; Sukop, M. C.

    2006-12-01

    Lattice Boltzmann Methods (LBMs) have been under development for the last two decades and have become another capable numerical method for simulating fluid flow. Recent advances in lattice Boltzmann applications involve simulation of density-dependent fluid flow in closed (Dixit and Babu, 2006; D'Orazio et al., 2004) or periodic (Guo and Zhao, 2005) domains. However, standard pressure boundary conditions (BCs) are incompatible with concentration-dependent density flow simulations that use a body force for gravity. An implementation of hydrostatic BCs for use under these conditions is proposed here. The basis of this new implementation is an additional term in the pressure BC. It is derived to account for the incorporation of gravity as a body force and the effect of varying concentration in the fluid. The hydrostatic BC expands the potential of density-dependent LBM to simulate domains with boundaries other than the closed or periodic boundaries that have appeared in previous literature on LBM simulations. With this new implementation, LBM will be able to simulate complex concentration-dependent density flows, such as salt water intrusion in the classic Henry and Henry-Hilleke problems. This is demonstrated using various examples, beginning with a closed box system, and ending with a system containing two solid walls, one velocity boundary and one pressure boundary, as in the Henry problem. References Dixit, H. N., V. Babu, (2006), Simulation of high Rayleigh number natural convection in a square cavity using the lattice Boltzmann method, Int. J. Heat Mass Transfer, 49, 727-739. D'Orazio, A., M. Corcione, G.P. Celata, (2004), Application to natural convection enclosed flows of a lattice Boltzmann BGK model coupled with a general purpose thermal boundary conditions, Int. J. Thermal Sci., 43, 575-586. Gou, Z., T.S. Zhao, (2005), Lattice Boltzmann simulation of natural convection with temperature-dependant viscosity in a porous cavity, Numerical Heat Transfer, Part B

  17. Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval.

    PubMed

    Zhang, Renhua; Tian, Jing; Su, Hongbo; Sun, Xiaomin; Chen, Shaohui; Xia, Jun

    2008-10-01

    In order to make the prediction of land surface heat fluxes more robust, two improvements were made to an operational two-layer model proposed previously by Zhang. These improvements are: 1) a surface energy balance method is used to determine the theoretical boundary lines (namely 'true wet/cool edge' and 'true dry/warm edge' in the trapezoid) in the scatter plot for the surface temperature versus the fractional vegetation cover in mixed pixels; 2) a new assumption that the slope of the Tm - f curves is mainly controlled by soil water content is introduced. The variables required by the improved method include near surface vapor pressure, air temperature, surface resistance, aerodynamic resistance, fractional vegetation cover, surface temperature and net radiation. The model predictions from the improved model were assessed in this study by in situ measurements, which show that the total latent heat flux from the soil and vegetation are in close agreement with the in situ measurement with an RMSE (Root Mean Square Error) ranging from 30 w/m²~50 w/m²,which is consistent with the site scale measurement of latent heat flux. Because soil evaporation and vegetation transpiration are not measured separately from the field site, in situ measured CO₂ flux is used to examine the modeled λEveg. Similar trends of seasonal variations of vegetation were found for the canopy transpiration retrievals and in situ CO₂ flux measurements. The above differences are mainly caused by 1) the scale disparity between the field measurement and the MODIS observation; 2) the non-closure problem of the surface energy balance from the surface fluxes observations themselves. The improved method was successfully used to predict the component surface heat fluxes from the soil and vegetation and it provides a promising approach to study the canopy transpiration and the soil evaporation quantitatively during the rapid growing season of winter wheat in northern China.

  18. Two-layer tree-connected feed-forward neural network model for neural cryptography

    NASA Astrophysics Data System (ADS)

    Lei, Xinyu; Liao, Xiaofeng; Chen, Fei; Huang, Tingwen

    2013-03-01

    Neural synchronization by means of mutual learning provides an avenue to design public key exchange protocols, bringing about what is known as neural cryptography. Two identically structured neural networks learn from each other and reach full synchronization eventually. The full synchronization enables two networks to have the same weight, which can be used as a secret key for many subsequent cryptographic purposes. It is striking to observe that after the first decade of neural cryptography, the tree parity machine (TPM) network with hidden unit K=3 appears to be the sole network that is suitable for a neural protocol. No convincingly secure neural protocol is well designed by using other network structures despite considerable research efforts. With the goal of overcoming the limitations of a suitable network structure, in this paper we develop a two-layer tree-connected feed-forward neural network (TTFNN) model for a neural protocol. The TTFNN model captures the notion that two partners are capable of exchanging a vector with multiple bits in each time step. An in-depth study of the dynamic process of TTFNN-based protocols is then undertaken, based upon which a feasible condition is theoretically obtained to seek applicable protocols. Afterward, according to two analytically derived heuristic rules, a complete methodology for designing feasible TTFNN-based protocols is elaborated. A variety of feasible neural protocols are constructed, which exhibit the effectiveness and benefits of the proposed model. With another look from the perspective of application, TTFNN-based instances, which can outperform the conventional TPM-based protocol with respect to synchronization speed, are also experimentally confirmed.

  19. Contributions of the Elasticity to the Precession of a Two-layer Earth Model

    NASA Astrophysics Data System (ADS)

    Baenas, T.; Ferrándiz, J. M.; Escapa, A.; Getino, J.; Navarro, J. F.

    2017-02-01

    We focus on the updating of a specific contribution to the precession of the equator in longitude, usually named as “second order.” It stems from the crossing of certain terms of the lunisolar gravitational potential. The IAU2006 precession theory assigns it the value of ‑46.8 mas/cy that was derived for a rigid Earth model. Instead of that model, we consider a two-layer Earth composed of an elastic mantle and a liquid core, working out the problem within the Hamiltonian framework developed by Getino and Ferrándiz. The targeted effect is obtained without further simplifying assumptions through Hori’s canonical perturbation method applied up to the second order of perturbation. On account of using a more realistic Earth model, the revised value of the second-order contribution is significantly changed and reaches ‑55.29 mas/cy. That variation of the second-order contribution is larger than other contributions included in IAU2006. It must be compensated with an increase of ‑8.51 mas/cy in the value of the lunisolar first-order component {p}A\\prime of the precession of the equator rate, which is derived from the total rate by subtracting the remaining contributions accounted for in IAU2006 precession. The updating of the second-order contribution implies that the {p}A\\prime parameter has to be changed, from 5040684.593 to 5040693.104 mas/cy in absence of potential revisions of other contributions. It entails a proportional variation of Earth’s dynamical ellipticity Hd, for which the estimation associated with IAU2006, 0.00327379448, should be updated to 0.00327380001, about 1.7 ppm larger.

  20. Particle Dispersion Within Zonal Jets in Two-Layer Beta-Plane Turbulence

    DTIC Science & Technology

    2011-07-21

    shows that the rate of diffusion due to turbulent motions is several orders of magnitude larger than the molecular diffusion rate. Given an isotropic...may be written as KT ( ’j) /(I VO1) and dimensional analysis yields KT , ’ (U0)/(0/L) = UL. The ratio of the eddy diffusivity to the molecular ...Reynolds number of the flow. Thus, the Reynolds number of a turbulent flow can be thought of as the ratio of molecular diffusion to turbulent diffusion

  1. Analysis of a two row hydrostatic journal bearing with variable properties, inertia effects and surface roughness

    NASA Technical Reports Server (NTRS)

    Braun, M. J.; Adams, M. L.; Mullen, R. L.

    1985-01-01

    A computer algorithm for simulation of hydrostatic journal bearing pressure-flow behavior has been generated. The effects taken into account are inertia, cavitation, variable properties (isothermal bearing) and roughness. The program has been specifically tailored for simulation of the hybrid bearing of the cryogenic turbopumps of the main shuttle engine. Due to the high pressure (515 psia) of the supply line no cavitation has been found. The influence of the roughness effects have been found to become important only when the surface-roughness order of magnitude is comparable with that of the bearing clearance itself. Pocket edge inertia and variable properties have been found to have quite an important influence upon the pocket pressure, field pressure distribution and lubricant mass flow.

  2. Analysis of a two row hydrostatic journal bearing with variable properties, inertia effects and surface roughness

    NASA Technical Reports Server (NTRS)

    Braun, M. J.; Adams, M. L.; Mullen, R. L.

    1985-01-01

    A computer algorithm for simulation of hydrostatic journal bearing pressure-flow behavior has been generated. The effects taken into account are inertia, cavitation, variable properties (isothermal bearing) and roughness. The program has been specifically tailored for simulation of the hybrid bearing of the cryogenic turbopumps of the main shuttle engine. Due to the high pressure (515 psia) of the supply line no cavitation has been found. The influence of the roughness effects have been found to become important only when the surface-roughness order of magnitude is comparable with that of the bearing clearance itself. Pocket edge inertia and variable properties have been found to have quite an important influence upon the pocket pressure, field pressure distribution and lubricant mass flow.

  3. Noninvasive determination of the optical properties of two-layered turbid media from time-resolved reflectance measurements

    NASA Astrophysics Data System (ADS)

    Kienle, Alwin; Glanzmann, Thomas M.; Wagnieres, Georges A.; van den Bergh, Hubert

    1999-01-01

    The influence of the adipose tissue thickness on near- infrared spectroscopy to monitor the hemodynamics in muscles in investigated. It is shown by calculation of the mean optical pathlength of two-layered turbid media that the validity of the modified Beer-Lambert law is reduced with increasing thickness of the first layer (fat), because the assumption, that the mean optical pathlength is constant, is not fulfilled. In order to avoid these problems we demonstrate that it is possible to derive the optical properties of both layers from time-resolved reflectance measurements using a solution of the two-layered diffusion equation if the thickness of the first layer is known.

  4. Two-layer method (UW solution/perfluorochemical plus O2) for lung preservation in rat lung transplantation.

    PubMed

    Liu, C-C; Hsu, P-K; Huang, W-C; Huang, M-H; Hsu, H-S

    2007-12-01

    A new preservation method using perfluorochemicals (PFC) with oxygen administered continuously was developed for lung preservation and compared with traditional cold preservation methods for rat lung transplantation. Male Sprague-Dawley rats underwent orthotopic left lung transplantations of grafts preserved in lactiated Ringers solution (LR), University of Wisconsin solution (UW), Celsior solution, or a two-layer (PFC plus O2) solution for 6 hours. One hour after reperfusion, the right pulmonary artery and bronchus were clamped and 5 minutes later we recorded peak airway pressure and PaO2 level. The isograft was excised for measurement of myeloperoxidase activity, wet-to-dry ratio, and histologic examination to evaluate isograft function. The mean peak airway pressure was 29.80+/-6.72 mm H2O in the LR group, 28.80+/-5.76 mm H2O in the UW group, 33.60+/-5.17 mm H2O in the Celsior group, and 32.40+/-2.60 in the two-layer group. The mean PaO2 level was 99.78+/-76.09 mm Hg in the LR group, 87.84+/-33.58 mm Hg in the UW group, 104.50+/-72.93 mm Hg in the Celsior group, and 62.08+/-31.34 mm Hg in PFC and UW solution plus O2 group (two layers). The mean net myeloperoxidase activity OD level was 0.110+/-0.104 in the LR group, 0.392+/-0.328 in the UW group, 0.351+/-0.620 in the Celsior group, and 0.532+/-0.616 in the two-layer group. The mean wet-to-dry ratio was 7.47+/-1.60 in the LR group, 6.56+/-0.62 in the UW group, 7.54+/-2.19 in the Celsior group, and 5.32+/-2.20 in the two-layer group. The differences between groups in these parameters were not significant. Upon histologic examination, more inflammatory cell aggregates were seen in the two-layer group, less in the LR and the Celsior groups. The function of the lung graft after 6 hours of storage was not better using this two-layer method for preservation than traditional preservation methods in rat lung transplantation. Histologic examination revealed more inflammatory cell aggregates in the lung graft preserved

  5. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... supporting structure during the hydrostatic test should be considered. The design shall consider the combined stress during hydrostatic testing due to pressure and the support reactions. This stress shall not exceed... the supporting structure during hydrostatic testing should be considered in the design. (c)...

  6. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... supporting structure during the hydrostatic test should be considered. The design shall consider the combined stress during hydrostatic testing due to pressure and the support reactions. This stress shall not exceed... the supporting structure during hydrostatic testing should be considered in the design. (c)...

  7. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... supporting structure during the hydrostatic test should be considered. The design shall consider the combined stress during hydrostatic testing due to pressure and the support reactions. This stress shall not exceed... the supporting structure during hydrostatic testing should be considered in the design. (c)...

  8. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... supporting structure during the hydrostatic test should be considered. The design shall consider the combined stress during hydrostatic testing due to pressure and the support reactions. This stress shall not exceed... the supporting structure during hydrostatic testing should be considered in the design. (c)...

  9. 46 CFR 54.10-10 - Standard hydrostatic test (modifies UG-99).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... supporting structure during the hydrostatic test should be considered. The design shall consider the combined stress during hydrostatic testing due to pressure and the support reactions. This stress shall not exceed... the supporting structure during hydrostatic testing should be considered in the design. (c)...

  10. Hydrostatic self-aligning axial/torsional mechanism

    DOEpatents

    O'Connor, Daniel G.; Gerth, Howard L.

    1990-01-01

    The present invention is directed to a self-aligning axial/torsional loading mechanism for testing the strength of brittle materials which are sensitive to bending moments. Disposed inside said self-aligning loading mechanism is a frictionless hydrostatic ball joint with a flexure ring to accommodate torsional loads through said ball joint.

  11. Hybrid hydrostatic/ball bearings in high-speed turbomachinery

    NASA Technical Reports Server (NTRS)

    Nielson, C. E.

    1983-01-01

    A high speed, high pressure liquid hydrogen turbopump was designed, fabricated, and tested under a previous contract. This design was then modified to incorporate hybrid hydrostatic/ball bearings on both the pump end and turbine end to replace the original conventional ball bearing packages. The design, analysis, turbopump modification, assembly, and testing of the turbopump with hybrid bearings is presented here. Initial design considerations and rotordynamic performance analysis was made to define expected turbopump operating characteristics and are reported. The results of testing the turbopump to speeds of 9215 rad/s (88,000 rpm) using a wide range of hydrostatic bearing supply pressures are presented. The hydrostatic bearing test data and the rotordynamic behavior of the turbopump was closely analyzed and are included in the report. The testing of hybrid hydrostatic/ball bearings on a turbopump to the high speed requirements has indicated the configuration concept is feasible. The program has presented a great deal of information on the technology requirements of integrating the hybrid bearing into high speed turbopump designs for improved bearing life.

  12. Implausibility of Hydrostatic Funnels Constituting the Sun's Upper Transition Region

    NASA Astrophysics Data System (ADS)

    Oluseyi, Hakeem M.; Carpio, Melisa M.; Sheung, Janet

    2007-09-01

    Over the past thirty years, two bodies of literature have developed in parallel presenting mutually exclusive views of the Sun’s upper transition region. One model holds that the Sun’s upper-transition-region plasmas are confined primarily in hydrostatic funnels with a substantial backheating component. The other model holds that discrete structures, which are effectively isolated from the corona, predominate in the Sun’s upper transition region. Purveyors of the latter position have recently begun to present near-resolved observations of discrete structures. The funnel scenario, in contrast, has only been addressed by modeling unresolved upper transition region emission. To address this paradox we have constructed hydrostatic funnel models and tested them against a wider set of solar observations than previously performed. We reproduce the results of the previous analyses, yet find that the hydrostatic funnels are unable to self-consistently match the wider set of observations against which we test the models. We show that it is not possible for a class of funnels having peak temperatures in the transition region or in the corona to match the observations. We conclude that it is implausible that a class of hydrostatic funnels constitutes the dominant emitting component of the Sun’s upper-transition-region plasmas as has been suggested.

  13. Comparison of hydrostatic and hydrodynamic pressure to inactivate foodborne viruses

    USDA-ARS?s Scientific Manuscript database

    The effect of high hydrostatic pressure (HPP) and hydrodynamic pressure (HDP), in combination with chemical treatments, was evaluated for inactivation of foodborne viruses and non-pathogenic surrogates in a pork sausage product. Sausages were immersed in water, 100 ppm EDTA, or 2 percent lactoferrin...

  14. Design and validation of an automated hydrostatic weighing system.

    PubMed

    McClenaghan, B A; Rocchio, L

    1986-08-01

    The purpose of this study was to design and evaluate the validity of an automated technique to assess body density using a computerized hydrostatic weighing system. An existing hydrostatic tank was modified and interfaced with a microcomputer equipped with an analog-to-digital converter. Software was designed to input variables, control the collection of data, calculate selected measurements, and provide a summary of the results of each session. Validity of the data obtained utilizing the automated hydrostatic weighing system was estimated by: evaluating the reliability of the transducer/computer interface to measure objects of known underwater weight; comparing the data against a criterion measure; and determining inter-session subject reliability. Values obtained from the automated system were found to be highly correlated with known underwater weights (r = 0.99, SEE = 0.0060 kg). Data concurrently obtained utilizing the automated system and a manual chart recorder were also found to be highly correlated (r = 0.99, SEE = 0.0606 kg). Inter-session subject reliability was determined utilizing data collected on subjects (N = 16) tested on two occasions approximately 24 h apart. Correlations revealed high relationships between measures of underwater weight (r = 0.99, SEE = 0.1399 kg) and body density (r = 0.98, SEE = 0.00244 g X cm-1). Results indicate that a computerized hydrostatic weighing system is a valid and reliable method for determining underwater weight.

  15. A Hypothesis for the Sensitivity of AGCMs to Horizontal Resolution at Hydrostatic Scales

    NASA Astrophysics Data System (ADS)

    Herrington, A. R.; Reed, K. A.

    2016-12-01

    Variable and adaptive grids are a promising method for improving weather prediction and regional climate projections using global atmospheric general circulation models (AGCMs). These non-uniform grids require closure models that can faithfully represent unresolved scales for a range of truncation scales represented on the grid. The widely reported sensitivity of AGCM solutions to horizontal resolution indicates that present closure formulations are inadequate for non-uniform grids. An explanation for the sensitivity of the Community Atmosphere Model (CAM) to horizontal resolution is developed from a convergence study in an idealized aqua-planet configuration. We hypothesize that an increase in horizontal resolution results in a reduction in horizontal scale of the diabatic forcing from the physics package, facilitating fine scale flow and faster resolved vertical motion by the dynamical core, consistent with linear Boussinesq theory. A set of dry dynamical core tests have been developed to test our hypothesis, using a simple warm bubble as a surrogate physics forcing. The results of our dry tests are consistent with Boussinesq theory and our hypothesis. We discuss the implications of our hypothesis, including the development of `scale-aware' closures for hydrostatic and non-hydrostatic models.

  16. Hyperbaric chamber for evaluating hydrostatic pressure effects on tissues and cells.

    PubMed

    Hogan, P M; Ornhagen, H C; Doubt, T J; Laraway, B S; Morin, R A; Zaharkin, J

    1981-03-01

    A chamber system is described for the study of pure hydrostatic pressure effects on tissues and cells. The small chamber has an internal volume of 7.6 liters and is rated for working pressures up to 400 ATA. Sliding doors at each end permit easy access and quick sealing. A cam-driven pump provides constant flow of physiological solution to the tissue bath containing the preparation. Connections to the pump allow a variety of test solutions to be used in the course of an experiment. The tissue bath is designed to prevent chamber gas from diffusing in to the perfusate, thus allowing for pure hydrostatic compression of the bath contents. The bath is coupled to a motorized stage to facilitate placement of recording devices once the bath is placed inside the chamber. Temperature is controlled within 0.05 degrees C of set point by thermoelectric modules coupled to a feedback amplifier. This system has been used for electrical and mechanical studies of cardiac muscle, but its versatility makes it suitable for a wide range of other biomedical applications.

  17. Hydrostatic Simulation of Earth's Atmospheric Gas Using Multi-particle Collision Dynamics

    NASA Astrophysics Data System (ADS)

    Pattisahusiwa, Asis; Purqon, Acep; Viridi, Sparisoma

    2016-01-01

    Multi-particle collision dynamics (MPCD) is a mesoscopic simulation method to simulate fluid particle-like flows. MPCD has been widely used to simulate various problems in condensed matter. In this study, hydrostatic behavior of gas in the Earth's atmospheric layer is simulated by using MPCD method. The simulation is carried out by assuming the system under ideal state and is affected only by gravitational force. Gas particles are homogeneous and placed in 2D box. Interaction of the particles with the box is applied through implementation of boundary conditions (BC). Periodic BC is applied on the left and the right side, specular reflection on the top side, while bounce-back on the bottom side. Simulation program is executed in Arch Linux and running in notebook with processor Intel i5 @2700 MHz with 10 GB DDR3 RAM. The results show behaviors of the particles obey kinetic theory for ideal gas when gravitational acceleration value is proportional to the particle mass. Density distribution as a function of altitude also meets atmosphere's hydrostatic theory.

  18. Vertical discretization with finite elements for a global hydrostatic model on the cubed sphere

    NASA Astrophysics Data System (ADS)

    Yi, Tae-Hyeong; Park, Ja-Rin

    2017-06-01

    A formulation of Galerkin finite element with basis-spline functions on a hybrid sigma-pressure coordinate is presented to discretize the vertical terms of global Eulerian hydrostatic equations employed in a numerical weather prediction system, which is horizontally discretized with high-order spectral elements on a cubed sphere grid. This replaces the vertical discretization of conventional central finite difference that is first-order accurate in non-uniform grids and causes numerical instability in advection-dominant flows. Therefore, a model remains in the framework of Galerkin finite elements for both the horizontal and vertical spatial terms. The basis-spline functions, obtained from the de-Boor algorithm, are employed to derive both the vertical derivative and integral operators, since Eulerian advection terms are involved. These operators are used to discretize the vertical terms of the prognostic and diagnostic equations. To verify the vertical discretization schemes and compare their performance, various two- and three-dimensional idealized cases and a hindcast case with full physics are performed in terms of accuracy and stability. It was shown that the vertical finite element with the cubic basis-spline function is more accurate and stable than that of the vertical finite difference, as indicated by faster residual convergence, fewer statistical errors, and reduction in computational mode. This leads to the general conclusion that the overall performance of a global hydrostatic model might be significantly improved with the vertical finite element.

  19. Renal interstitial hydrostatic pressure and pressure natriuresis in pregnant rats.

    PubMed

    Khraibi, A A

    2000-08-01

    The objective of this study was to test the hypothesis that a decrease in renal interstitial hydrostatic pressure (RIHP) accounts for the blunted pressure natriuresis during pregnancy. RIHP was measured in nonpregnant (NP; n = 9), midterm pregnant (MP; 12-14 days after conception; n = 10), and late-term pregnant (LP; 18-21 days after conception; n = 12) female Sprague-Dawley rats at two renal perfusion pressure (RPP) levels (99 and 120 mmHg). At the lower RPP level, RIHP was 5.9 +/- 0.3 mmHg for NP, 3.4 +/- 0.4 mmHg for MP (P < 0.05 vs. NP), and 2.9 +/- 0.1 mmHg for LP (P < 0.05 vs. NP) rats. The increase in RPP from 99 to 120 mmHg resulted in pressure natriuretic and diuretic responses in all groups; however, the increases in fractional excretion of sodium (DeltaFE(Na)), urine flow rate (DeltaV), and DeltaRIHP were significantly greater (P < 0. 05) in NP compared with both MP and LP rats. DeltaFE(Na), DeltaV, and DeltaRIHP were 2.06 +/- 0.28%, 81.44 +/- 14.10 microl/min, and 3. 0 +/- 0.5 mmHg for NP; 0.67 +/- 0.13%, 28.03 +/- 5.28 microl/min, and 0.5 +/- 0.2 mmHg for MP; and 0.48 +/- 0.12%, 18.14 +/- 4.70 microl/min, and 0.4 +/- 0.1 mmHg for LP rats. In conclusion, RIHP is significantly lower in pregnant compared with nonpregnant rats at similar RPP levels. Also, the ability of pregnant rats to increase RIHP in response to an increase in RPP is blunted. These changes in RIHP may play an important role in the blunted pressure natriuresis and contribute to the conservation of sodium and water that is critical for fetal growth and development during normal pregnancy.

  20. Restoration of the contact surface in FORCE-type centred schemes II: Non-conservative one- and two-layer two-dimensional shallow water equations

    NASA Astrophysics Data System (ADS)

    Canestrelli, Alberto; Toro, Eleuterio F.

    2012-10-01

    Recently, a non-conservative well-balanced FORCE-type scheme has been proposed for solving multidimensional non-conservative equations such as the shallow water equations [4], the two-fluid flow model of Pitman and Le and the two- and three-dimensional Baer-Nunziato equations for compressible multiphase flows [17]. In the present paper the original scheme is first rewritten in a suitable form that allows easy manipulation of numerical fluxes. We then propose a modified scheme that provides a better resolution of contact waves for both one-layer and two-layer shallow water models. The improvement is particularly evident when an additional equation is solved for a passive solute. In this case, the original scheme does not satisfy the C-property for a uniformly distribute tracer, whereas the modified scheme provides a solution that is exact up to machine precision. Moreover, the modified scheme better resolves contact discontinuities, with an accuracy close to the one provided by a fully-upwind non-conservative ROE-type scheme accounting for the complete wave structure. When higher orders are achieved, the difference in accuracy between the various schemes is less pronounced. Moreover, the capability of the two-dimensional scheme to capture steady states is analyzed for both straight and meandering non-flat channels with non-zero friction, and for both one-layer and two-layer equations. Whereas the original first order FORCE scheme is able to correctly reproduce the longitudinal profile in the case of a straight channel even on a coarse mesh, when the channel is strongly meandering a modification of the scheme is necessary, otherwise a very refined mesh and a very high order of accuracy are needed, with a notable increase of computational time.

  1. Screen-Capturing System with Two-Layer Display for PowerPoint Presentation to Enhance Classroom Education

    ERIC Educational Resources Information Center

    Lai, Yen-Shou; Tsai, Hung-Hsu; Yu, Pao-Ta

    2011-01-01

    This paper proposes a new presentation system integrating a Microsoft PowerPoint presentation in a two-layer method, called the TL system, to promote learning in a physical classroom. With the TL system, teachers can readily control hints or annotations as a way of making them visible or invisible to students so as to reduce information load. In…

  2. Algorithm to Identify Frequent Coupled Modules from Two-Layered Network Series: Application to Study Transcription and Splicing Coupling

    PubMed Central

    Li, Wenyuan; Dai, Chao; Liu, Chun-Chi

    2012-01-01

    Abstract Current network analysis methods all focus on one or multiple networks of the same type. However, cells are organized by multi-layer networks (e.g., transcriptional regulatory networks, splicing regulatory networks, protein-protein interaction networks), which interact and influence each other. Elucidating the coupling mechanisms among those different types of networks is essential in understanding the functions and mechanisms of cellular activities. In this article, we developed the first computational method for pattern mining across many two-layered graphs, with the two layers representing different types yet coupled biological networks. We formulated the problem of identifying frequent coupled clusters between the two layers of networks into a tensor-based computation problem, and proposed an efficient solution to solve the problem. We applied the method to 38 two-layered co-transcription and co-splicing networks, derived from 38 RNA-seq datasets. With the identified atlas of coupled transcription-splicing modules, we explored to what extent, for which cellular functions, and by what mechanisms transcription-splicing coupling takes place. PMID:22697243

  3. [Two-layer adhesive film Diplen-denta C--a new compound containing polymer base and active component Solcoseryl].

    PubMed

    Abakarova, D S

    2007-01-01

    Characteristics of the main components of a new effective long-lasting dosage form--biopolymer two-layer adhesive solcoseryl containing film Diplen-denta C--are presented. It has a potent wound-healing action on oral mucosa, retains therapeutic properties during long time, is self dissolving and can be easily fixed on oral mucous membrane.

  4. Screen-Capturing System with Two-Layer Display for PowerPoint Presentation to Enhance Classroom Education

    ERIC Educational Resources Information Center

    Lai, Yen-Shou; Tsai, Hung-Hsu; Yu, Pao-Ta

    2011-01-01

    This paper proposes a new presentation system integrating a Microsoft PowerPoint presentation in a two-layer method, called the TL system, to promote learning in a physical classroom. With the TL system, teachers can readily control hints or annotations as a way of making them visible or invisible to students so as to reduce information load. In…

  5. An in-vitro traumatic model to evaluate the response of myelinated cultures to sustained hydrostatic compression injury.

    PubMed

    Frieboes, Laura R; Gupta, Ranjan

    2009-12-01

    While a variety of in-vitro models have been employed to investigate the response of load-bearing tissues to hydrostatic pressure, long-term studies are limited by the need to provide for adequate gas exchange during pressurization. Applying compression in vitro may alter the equilibrium of the system and thereby disrupt the gas exchange kinetics. To address this, several sophisticated compression chamber designs have been developed. However, these systems are limited in the magnitude of pressure that can be applied and may require frequent media changes, thereby eliminating critical autocrine and paracrine signaling factors. To better isolate the cellular response to long-term compression, we created a model that features continuous gas flow through the chamber during pressurization, and a negative feedback control system to rigorously control dissolved oxygen levels. Monitoring dissolved oxygen continuously during pressurization, we find that the ensuing response exhibits characteristics of a second- or higher-order system which can be mathematically modeled using a second-order differential equation. Finally, we use the system to model chronic nerve compression injuries, such as carpal tunnel syndrome and spinal nerve root stenosis, with myelinated neuron-Schwann cell co-cultures. Cell membrane integrity assay results show that co-cultures respond differently to hydrostatic pressure, depending on the magnitude and duration of stimulation. In addition, we find that myelinated Schwann cells proliferate in response to applied hydrostatic compression.

  6. The application of ICOM, a non-hydrostatic, fully unstructured mesh model in large scale ocean domains

    NASA Astrophysics Data System (ADS)

    Kramer, Stephan C.; Piggott, Matthew D.; Cotter, Colin J.; Pain, Chris C.; Nelson, Rhodri B.

    2010-05-01

    There are many apparent advantages of the application of unstructured meshes in ocean modelling: a much better representation of the coastal boundaries, the ability to focus resolution in areas of interest, or areas of intensified flow, such as boundary currents, etc. In particular with adaptive mesh technology, where the mesh is adapted during the simulation as the flow evolves, one is able to resolve much smaller features in the often turbulent ocean flow, than would be possible with fixed, structured mesh models. The Imperial College Ocean Model[1], is a non-hydrostatic ocean model that employs fully unstructured adaptive meshes, that allow focussing of resolution not only in the horizontal but also in the vertical. This enables the modelling of physical processes, such as open ocean deep convection, density driven flows on a steep bottom topography, etc. that are very important for the global ocean circulation. The Imperial College Ocean Model has been applied succesfully in the modelling of many of these processes. On the other hand hydrostatic, layered ocean models have a significant advantage in large areas of the oceans where the hydrostatic assumption is valid. The fact that with fully unstructured meshes it is no longer straightforward to separate horizontal, baroptropic modes and vertical, baroclinic dynamics, has consequences for both numerical accuracy and the efficiency of the linear solvers. It has therefore been a challenge for ICOM to remain competitive in these areas with layered mesh models. These problems have been overcome by, amongst others, the development of a new mesh adaptation technique that maintains a columnar structure of the mesh in such areas. The application of multigrid techniques has improved the effiency of the non-hydrostatic pressure solve[2] in such a way that convergence is now independent of aspect ratio, which makes the pressure solve competitive with that of a hydrostatic model. In this contribution an overview will be

  7. Hydrostatic Pressure Sensing with High Birefringence Photonic Crystal Fibers

    PubMed Central

    Fávero, Fernando C.; Quintero, Sully M. M.; Martelli, Cicero; Braga, Arthur M.B.; Silva, Vinícius V.; Carvalho, Isabel C. S.; Llerena, Roberth W. A.; Valente, Luiz C. G.

    2010-01-01

    The effect of hydrostatic pressure on the waveguiding properties of high birefringence photonic crystal fibers (HiBi PCF) is evaluated both numerically and experimentally. A fiber design presenting form birefringence induced by two enlarged holes in the innermost ring defining the fiber core is investigated. Numerical results show that modal sensitivity to the applied pressure depends on the diameters of the holes, and can be tailored by independently varying the sizes of the large or small holes. Numerical and experimental results are compared showing excellent agreement. A hydrostatic pressure sensor is proposed and demonstrated using an in-fiber modal interferometer where the two orthogonally polarized modes of a HiBi PCF generate fringes over the optical spectrum of a broad band source. From the analysis of experimental results, it is concluded that, in principle, an operating limit of 92 MPa in pressure could be achieved with 0.0003% of full scale resolution. PMID:22163435

  8. Air Bearings Machined On Ultra Precision, Hydrostatic CNC-Lathe

    NASA Astrophysics Data System (ADS)

    Knol, Pierre H.; Szepesi, Denis; Deurwaarder, Jan M.

    1987-01-01

    Micromachining of precision elements requires an adequate machine concept to meet the high demand of surface finish, dimensional and shape accuracy. The Hembrug ultra precision lathes have been exclusively designed with hydrostatic principles for main spindle and guideways. This concept is to be explained with some major advantages of hydrostatics compared with aerostatics at universal micromachining applications. Hembrug has originally developed the conventional Mikroturn ultra precision facing lathes, for diamond turning of computer memory discs. This first generation of machines was followed by the advanced computer numerically controlled types for machining of complex precision workpieces. One of these parts, an aerostatic bearing component has been succesfully machined on the Super-Mikroturn CNC. A case study of airbearing machining confirms the statement that a good result of the micromachining does not depend on machine performance alone, but also on the technology applied.

  9. Hydrostatic pressure sensing with high birefringence photonic crystal fibers.

    PubMed

    Fávero, Fernando C; Quintero, Sully M M; Martelli, Cicero; Braga, Arthur M B; Silva, Vinícius V; Carvalho, Isabel C S; Llerena, Roberth W A; Valente, Luiz C G

    2010-01-01

    The effect of hydrostatic pressure on the waveguiding properties of high birefringence photonic crystal fibers (HiBi PCF) is evaluated both numerically and experimentally. A fiber design presenting form birefringence induced by two enlarged holes in the innermost ring defining the fiber core is investigated. Numerical results show that modal sensitivity to the applied pressure depends on the diameters of the holes, and can be tailored by independently varying the sizes of the large or small holes. Numerical and experimental results are compared showing excellent agreement. A hydrostatic pressure sensor is proposed and demonstrated using an in-fiber modal interferometer where the two orthogonally polarized modes of a HiBi PCF generate fringes over the optical spectrum of a broad band source. From the analysis of experimental results, it is concluded that, in principle, an operating limit of 92 MPa in pressure could be achieved with 0.0003% of full scale resolution.

  10. Rectangular Shell Plating Under Uniformly Distributed Hydrostatic Pressure

    NASA Technical Reports Server (NTRS)

    Neubert, M; Sommer, A

    1940-01-01

    A check of the calculation methods used by Foppl and Henky for investigating the reliability of shell plating under hydrostatic pressure has proved that the formulas yield practical results within the elastic range of the material. Foppl's approximate calculation leaves one on the safe side. It further was found on the basis of the marked ductility of the shell plating under tensile stress that the strength is from 50 to 100 percent higher in the elastic range than expected by either method.

  11. Steel pressure vessels for hydrostatic pressures to 50 kilobars.

    PubMed

    Lavergne, A; Whalley, E

    1978-07-01

    Cylindrical steel pressure vessels are described that can be used for hydrostatic pressures up to 50 kilobars. Monoblock vessels of 350 maraging steel can be used to 40 kilobars and compound vessels with an inner vessel of 350 maraging steel and an outer vessel of 300 maraging steel to 50 kilobars. Neither requires the cylinder to be end loaded, and so they are much easier to use than the more usual compound vessels with a tungsten carbide inner and steel outer vessel.

  12. A fully coupled variable properties thermohydraulic model for a cryogenic hydrostatic journal bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. J.; Wheeler, R. L., III; Hendricks, R. C.

    1986-01-01

    The goal set forth here is to continue the work started by Braun et al. (1984-1985) and present an integrated analysis of the behavior of the two row, 20 staggered pockets, hydrostatic cryogenic bearing used by the turbopumps of the Space Shuttle main engine. The variable properties Reynolds equation is fully coupled with the two-dimensional fluid film energy equation. The three-dimensional equations of the shaft and bushing model the boundary conditions of the fluid film energy equation. The effects of shaft eccentricity, angular velocity, and inertia pressure drops at pocket edge are incorporated in the model. Their effects on the bearing fluid properties, load carrying capacity, mass flow, pressure, velocity, and temperature form the ultimate object of this paper.

  13. A fully coupled variable properties thermohydraulic model for a cryogenic hydrostatic journal bearing

    NASA Technical Reports Server (NTRS)

    Braun, M. J.; Wheeler, R. L., III; Hendricks, R. C.

    1986-01-01

    The goal set forth here is to continue the work started by Braun et al. (1984-1985) and present an integrated analysis of the behavior of the two row, 20 staggered pockets, hydrostatic cryogenic bearing used by the turbopumps of the Space Shuttle main engine. The variable properties Reynolds equation is fully coupled with the two-dimensional fluid film energy equation. The three-dimensional equations of the shaft and bushing model the boundary conditions of the fluid film energy equation. The effects of shaft eccentricity, angular velocity, and inertia pressure drops at pocket edge are incorporated in the model. Their effects on the bearing fluid properties, load carrying capacity, mass flow, pressure, velocity, and temperature form the ultimate object of this paper.

  14. Hydrostatic levelling systems: Measuring at the system limits

    NASA Astrophysics Data System (ADS)

    Meier, Edi; Geiger, Alain; Ingensand, Hilmar; Licht, Hans; Limpach, Philippe; Steiger, Andreas; Zwyssig, Roger

    2010-09-01

    Three hydrostatic displacement monitoring system applications in Switzerland are discussed; the first concerns experience gained monitoring the foundation of the Albigna dam, the second relating to the underground stability of the Swiss Light Source synchrotron and the third concerning the deformation of a bridge near the city of Lucerne. Two different principles were applied, the Hydrostatic Levelling System (HLS) using the “half-filled pipe principle” developed by the Paul Scherrer Institute and the Large Area Settlement System (LAS) using the “differential pressure principle”. With both systems ground deformations induced by tidal forces can be seen. However, high accuracy of single sensors is not sufficient. A well-designed configuration of the complete system is equally important. On the other hand there are also limits imposed by installation logistics and by the environmental conditions. An example is the bridge monitoring application, where the acceleration along the bridge due to the passage of heavy trucks limits the feasibility of using hydrostatic levelling measurements.

  15. Muscular hydrostat mechanism for lip protrusion in speech

    NASA Astrophysics Data System (ADS)

    Murano, Emi Z.; Stone, Maureen; Honda, Kiyoshi

    2005-09-01

    The lip is an organ consisting mostly of muscle similar to the tongue. While the tongue is known as a muscular hydrostat, it is unclear whether the lip is also. In this paper the muscular hydrostat issue was explored from the anatomical and functional point of view using high-resolution static MRI (hr-MRI 0.125 mm/pixel) and tagged-cineMRI (t-MRI). A 3-D reconstruction of the lips and its muscles was obtained from hr-MRI during sustained vowels /i/ and /u/. The muscular geometry of the orbicularis oris, mentalis, and depressor labii inferior muscles were superimposed onto the principal strains that depicts compression and expansion of the internal tissue obtained from t-MRI. It is shown that (1) orbicularis oris muscle shape can predict both the borderline of glabrous and hairy skin and the manner in which the lips are protruded; (2) the lips volume is almost identical for both speech tasks; and (3) direction and intensity of compression of orbicularis oris and mentalis muscle bundles imply the role of these muscles in the protrusion appearance. These results indicate that the muscular architecture and volume preserving characteristics of the lips are consistent with a muscular hydrostat. [This work was supported by NIH (USA) and NiCT (Japan).

  16. LAHRI: Laparoscopic-Assisted Hydrostatic Reduction of Intussusception.

    PubMed

    Geltzeiler, Cristina B; Sims, Thomas L; Zigman, Andrew F

    2015-09-01

    Intussusception is the most common cause of bowel obstruction in children from 3 months to 3 years of age. In the absence of peritonitis, initial treatment is either hydrostatic or pneumatic reduction. If these measures fail, operative intervention is required. In nonreducible cases, we propose the use of intraoperative hydrostatic enema to achieve or confirm reduction. In this study we describe a cohort of patients who have undergone laparoscopic-assisted hydrostatic reduction of intussusception (LAHRI). This is a retrospective cohort study of all patients undergoing LAHRI from the years 2011 to 2013. We performed LAHRI in seven children 4 months to 2 years of age. All patients had ileocolic intussusception that failed initial reduction by radiographic enema. With the patient under general anesthesia, saline enema reduction was facilitated by direct laparoscopic visualization. In 2 of the 7 cases, intussusception reduction was visually confirmed in real time, and only a laparoscopic camera port was required. In 1 patient, the bowel was extensively dilated, requiring mini-laparotomy for visualization. The enema, however, reduced the intussusception without any need for manual reduction. In the remaining 4 cases, minimal laparoscopic manipulation was required after the enema failed to completely reduce the intussusceptum, but enema was used to confirm reduction. No child required bowel resection. In cases of failed reduction by contrast enema, we have demonstrated LAHRI to be a successful treatment modality. The technique has the advantage of little to no bowel manipulation and has evolved into one performed via a single umbilical port.

  17. ATLAS-TPX: a two-layer pixel detector setup for neutron detection and radiation field characterization

    NASA Astrophysics Data System (ADS)

    Bergmann, B.; Caicedo, I.; Leroy, C.; Pospisil, S.; Vykydal, Z.

    2016-10-01

    A two-layer pixel detector setup (ATLAS-TPX), designed for thermal and fast neutron detection and radiation field characterization is presented. It consists of two segmented silicon detectors (256 × 256 pixels, pixel pitch 55 μm, thicknesses 300 μm and 500 μm) facing each other. To enhance the neutron detection efficiency a set of converter layers is inserted in between these detectors. The pixelation and the two-layer design allow a discrimination of neutrons against γs by pattern recognition and against charged particles by using the coincidence and anticoincidence information. The neutron conversion and detection efficiencies are measured in a thermal neutron field and fast neutron fields with energies up to 600 MeV. A Geant4 simulation model is presented, which is validated against the measured detector responses. The reliability of the coincidence and anticoincidence technique is demonstrated and possible applications of the detector setup are briefly outlined.

  18. Heat diffusion and thermolastic vibration influence on the signal of an open photoacoustic cell for two layer systems

    NASA Astrophysics Data System (ADS)

    Pichardo-Molina, J. L.; Alvarado-Gil, J. J.

    2004-06-01

    Thermal diffusion and thermoelastic vibration in two layer systems is studied using photoacoustic spectroscopy. Three different two layer systems, copper/lead-tin (Cu/Pb-Sn), aluminum/paint (Al/paint) and aluminum/polyvinyl-chloride (Al/PVC) are studied. A model is developed considering that both layers present thermoelastic vibration and heat diffusion. It is shown that our equations can be used to obtain the theoretical photoacoustic signal independent of the mechanical properties when the thermal and thermomechanical properties of the composing layers are similar. It is shown that this approximation is much better suited for the study of metal/metal systems where the coupling of the thermoelastic bending is smooth. The restrictions of this approach and the possible extensions to study systems with different thermal expansion and mechanical behavior are discussed.

  19. Separate and combined effects of static stability and shear variation on the baroclinic instability of a two-layer current

    NASA Technical Reports Server (NTRS)

    Hyun, J. M.

    1981-01-01

    Quasi-geostrophic disturbance instability characteristics are studied in light of a linearized, two-layer Eady model in which both the static stability and the zonal current shear are uniform but different in each layer. It is shown that the qualitative character of the instability is determined by the sign of the basic-state potential vorticity gradient at the layer interface, and that there is a qualitative similarity between the effects of Richardson number variations due to changes in static stability and those due to changes in shear. The two-layer model is also used to construct an analog of the Williams (1974) continuous model of generalized Eady waves, the basic state in that case having zero potential vorticity gradient in the interior. The model results are in good agreement with the earlier Williams findings.

  20. Two-layer critical dimensions and overlay process window characterization and improvement in full-chip computational lithography

    NASA Astrophysics Data System (ADS)

    Sturtevant, John L.; Liubich, Vlad; Gupta, Rachit

    2016-04-01

    Edge placement error (EPE) was a term initially introduced to describe the difference between predicted pattern contour edge and the design target for a single design layer. Strictly speaking, this quantity is not directly measurable in the fab. What is of vital importance is the relative edge placement errors between different design layers, and in the era of multipatterning, the different constituent mask sublayers for a single design layer. The critical dimensions (CD) and overlay between two layers can be measured in the fab, and there has always been a strong emphasis on control of overlay between design layers. The progress in this realm has been remarkable, accelerated in part at least by the proliferation of multipatterning, which reduces the available overlay budget by introducing a coupling of overlay and CD errors for the target layer. Computational lithography makes possible the full-chip assessment of two-layer edge to edge distances and two-layer contact overlap area. We will investigate examples of via-metal model-based analysis of CD and overlay errors. We will investigate both single patterning and double patterning. For single patterning, we show the advantage of contour-to-contour simulation over contour to target simulation, and how the addition of aberrations in the optical models can provide a more realistic CD-overlay process window (PW) for edge placement errors. For double patterning, the interaction of 4-layer CD and overlay errors is very complex, but we illustrate that not only can full-chip verification identify potential two-layer hotspots, the optical proximity correction engine can act to mitigate such hotspots and enlarge the joint CD-overlay PW.

  1. A new generation of the regional climate model REMO: REMO non-hydrostatic

    NASA Astrophysics Data System (ADS)

    Sieck, Kevin; Raub, Thomas; Marien, Lennart; Buntemeyer, Lars; Jacob, Daniela

    2016-04-01

    The regional climate model REMO is well established and has proofed it's value in regional climate simulations for more than a decade. However, due to the hydrostatic formulation REMO is not able to produce useful regional climate information on scales smaller than ~10 km. The demand for higher resolution data especially in the climate service sector is evident. Often climate change information on urban district or even point level is needed. A previous development of a non-hydrostatic dynamical core for REMO utilizing ideas of Miller and Pearce (1974) and Janjic (2001) has been picked up and implemented into the latest hydrostatic REMO version. One of the advantages of the Janjic formulation is that hydrostatic and non-hydrostatic computations are well separated. This offers a straightforward implementation of the non-hydrostatic calculations into an existing hydrostatic model. Other advantages are the easy quantification of the error done by the hydrostatic approximation and the lower computational costs at lower resolutions by switching of the non-hydrostatic part. We will show results from climate simulations on the EURO-CORDEX domain with and without non-hydrostatic option.

  2. Verification of a two-layer inverse Monte Carlo absorption model using multiple source-detector separation diffuse reflectance spectroscopy

    PubMed Central

    Sharma, Manu; Hennessy, Ricky; Markey, Mia K.; Tunnell, James W.

    2013-01-01

    A two-layer Monte Carlo lookup table-based inverse model is validated with two-layered phantoms across physiologically relevant optical property ranges. Reflectance data for source-detector separations of 370 μm and 740 μm were collected from these two-layered phantoms and top layer thickness, reduced scattering coefficient and the top and bottom layer absorption coefficients were extracted using the inverse model and compared to the known values. The results of the phantom verification show that this method is able to accurately extract top layer thickness and scattering when the top layer thickness ranges from 0 to 550 μm. In this range, top layer thicknesses were measured with an average error of 10% and the reduced scattering coefficient was measured with an average error of 15%. The accuracy of top and bottom layer absorption coefficient measurements was found to be highly dependent on top layer thickness, which agrees with physical expectation; however, within appropriate thickness ranges, the error for absorption properties varies from 12–25%. PMID:24466475

  3. Distributed Processing System for Restoration of Electric Power Distribution Network Using Two-Layered Contract Net Protocol

    NASA Astrophysics Data System (ADS)

    Kodama, Yu; Hamagami, Tomoki

    Distributed processing system for restoration of electric power distribution network using two-layered CNP is proposed. The goal of this study is to develop the restoration system which adjusts to the future power network with distributed generators. The state of the art of this study is that the two-layered CNP is applied for the distributed computing environment in practical use. The two-layered CNP has two classes of agents, named field agent and operating agent in the network. In order to avoid conflicts of tasks, operating agent controls privilege for managers to send the task announcement messages in CNP. This technique realizes the coordination between agents which work asynchronously in parallel with others. Moreover, this study implements the distributed processing system using a de-fact standard multi-agent framework, JADE(Java Agent DEvelopment framework). This study conducts the simulation experiments of power distribution network restoration and compares the proposed system with the previous system. We confirmed the results show effectiveness of the proposed system.

  4. Verification of a two-layer inverse Monte Carlo absorption model using multiple source-detector separation diffuse reflectance spectroscopy.

    PubMed

    Sharma, Manu; Hennessy, Ricky; Markey, Mia K; Tunnell, James W

    2013-12-02

    A two-layer Monte Carlo lookup table-based inverse model is validated with two-layered phantoms across physiologically relevant optical property ranges. Reflectance data for source-detector separations of 370 μm and 740 μm were collected from these two-layered phantoms and top layer thickness, reduced scattering coefficient and the top and bottom layer absorption coefficients were extracted using the inverse model and compared to the known values. The results of the phantom verification show that this method is able to accurately extract top layer thickness and scattering when the top layer thickness ranges from 0 to 550 μm. In this range, top layer thicknesses were measured with an average error of 10% and the reduced scattering coefficient was measured with an average error of 15%. The accuracy of top and bottom layer absorption coefficient measurements was found to be highly dependent on top layer thickness, which agrees with physical expectation; however, within appropriate thickness ranges, the error for absorption properties varies from 12-25%.

  5. Zwitterionic polymer-based platform with two-layer architecture for ultra low fouling and high protein loading.

    PubMed

    Huang, Chun-Jen; Li, Yuting; Jiang, Shaoyi

    2012-04-03

    High resistance to nonspecific adsorption typically accompanies loss of binding capacity and vice versa for many surface coatings and applications. In this study, a zwitterionic polycarboxybetaine acrylamide (pCB)-based binding platform with a "two-layer" structure for ultra low fouling and high protein loading properties was developed. The first pCB layer with a high packing density prepared under a water-free condition serves as a protective layer to resist nonspecific adsorption from complex media. The second pCB layer with a low packing density is used to achieve high protein binding capacity. Amounts of tetraethylthiuram disulfide (TED) and water in the reaction were varied to regulate the packing density and chain length of polymers, respectively, for the second pCB layer. The in situ modification of pCB films with antihuman thyroid stimulating hormone (TSH) IgG molecules and the detection of TSH antigens were employed to demonstrate high protein immobilization and high antigen detection capabilities of this "two-layer" structure. Undiluted blood plasma was used to test the nonfouling properties of this platform. Nonspecific and specific interactions were monitored by a surface plasmon resonance sensor. This work demonstrates great promise of this "two-layer" binding platform for the improved performance of biosensors.

  6. Estimation and imaging of breast lesions using a two-layer tissue structure by ultrasound-guided optical tomography

    PubMed Central

    Xu, Yan; Zhu, Quing

    2015-01-01

    Abstract. A new two-step estimation and imaging method is developed for a two-layer breast tissue structure consisting of a breast tissue layer and a chest wall underneath. First, a smaller probe with shorter distance source-detector pairs was used to collect the reflected light mainly from the breast tissue layer. Then, a larger probe with 9×14 source-detector pairs and a centrally located ultrasound transducer was used to collect reflected light from the two-layer tissue structure. The data collected from the smaller probe were used to estimate breast tissue optical properties. With more accurate estimation of the average breast tissue properties, the second layer properties can be assessed from data obtained from the larger probe. Using this approach, the unknown variables have been reduced from four to two and the estimated bulk tissue optical properties are more accurate and robust. In addition, a two-step reconstruction using a genetic algorithm and conjugate gradient method is implemented to simultaneously reconstruct the absorption and reduced scattering maps of targets inside a two-layer tissue structure. Simulations and phantom experiments have been performed to validate the new reconstruction method, and a clinical example is given to demonstrate the feasibility of this approach. PMID:26046722

  7. Modeling Microgravity Induced Fluid Redistribution Autoregulatory and Hydrostatic Enhancements

    NASA Technical Reports Server (NTRS)

    Myers, J. G.; Werner, C.; Nelson, E. S.; Feola, A.; Raykin, J.; Samuels, B.; Ethier, C. R.

    2017-01-01

    Space flight induces a marked cephalad (headward) redistribution of blood and interstitial fluid potentially resulting in a loss of venous tone and reduction in heart muscle efficiency upon introduction into the microgravity environment. Using various types of computational models, we are investigating how this fluid redistribution may induce intracranial pressure changes, relevant to reported reductions in astronaut visual acuity, part of the Visual Impairment and Intracranial Pressure (VIIP) syndrome. Methods: We utilize a lumped parameter cardiovascular system (CVS) model, augmented by compartments comprising the cerebral spinal fluid (CSF) space, as the primary tool to describe how microgravity, and the associated lack of hydrostatic gradient, impacts fluid redistribution. Models of ocular fluid pressures and biomechanics then accept the output of the above model as boundary condition input to allow more detailed, local analysis (see IWS Abstract by Ethier et al.). Recently, we enhanced the capabilities our previously reported CVS model through the implementation of robust autoregulatory mechanisms and a more fundamental approach to the implementation of hydrostatic mechanisms. Modifying the approach of Blanco et al., we implemented auto-regulation in a quasi-static manner, as an averaged effect across the span of one heartbeat. This approach reduced the higher frequency perturbations from the regulatory mechanism and was intended to allow longer simulation times (days) than models that implement within-beat regulatory mechanisms (minutes). A more fundamental approach to hydrostatics was implemented by a quasi-1D approach, in which compartment descriptions include compartment length, orientation and relative position, allowed for modeling of body orientation, relative body positioning and, in the future, alternative gravity environments. At this time the inclusion of hydrostatic mechanisms supplies additional capabilities to train and validate the CVS model

  8. Morphological and Physiological Characterization of Listeria monocytogenes Subjected to High Hydrostatic Pressure

    PubMed Central

    Ritz, M.; Tholozan, J. L.; Federighi, M.; Pilet, M. F.

    2001-01-01

    High hydrostatic pressure is a new food preservation technology known for its capacity to inactivate spoilage and pathogenic microorganisms. That inactivation is usually assessed by the number of colonies growing on solid media after treatment. Under normal conditions the method does not permit recovery of damaged cells and may underestimate the number of cells that will remain viable and grow after a few days in high-pressure-processed foodstuffs. This study investigated the damage inflicted on Listeria monocytogenes cells treated by high pressure for 10 min at 400 MPa in pH 5.6 citrate buffer. Under these conditions, no cell growth occurred after 48 h on plate count agar. Scanning electron microscopy, light scattering by flow cytometry, and cell volume measurements were compared to evaluate the morphological changes in cells after pressurization. All these methods revealed that cellular morphology was not really affected. Esterase activity, as assessed either by enzymatic activity assays or by carboxy fluorescein diacetate fluorescence monitored by flow cytometry, was dramatically lowered, but not totally obliterated, under the effects of treatment. The measurement of propidium iodide uptake followed by flow cytometry demonstrated that membrane integrity was preserved in a small part of the population, although the membrane potential measured by analytical methods or evaluated by oxonol uptake was reduced from −86 to −5 mV. These results showed that such combined methods as fluorescent dyes monitored by flow cytometry and physiological activity measurements provide valuable indications of cellular viability. PMID:11319107

  9. Morphological and physiological characterization of Listeria monocytogenes subjected to high hydrostatic pressure.

    PubMed

    Ritz, M; Tholozan, J L; Federighi, M; Pilet, M F

    2001-05-01

    High hydrostatic pressure is a new food preservation technology known for its capacity to inactivate spoilage and pathogenic microorganisms. That inactivation is usually assessed by the number of colonies growing on solid media after treatment. Under normal conditions the method does not permit recovery of damaged cells and may underestimate the number of cells that will remain viable and grow after a few days in high-pressure-processed foodstuffs. This study investigated the damage inflicted on Listeria monocytogenes cells treated by high pressure for 10 min at 400 MPa in pH 5.6 citrate buffer. Under these conditions, no cell growth occurred after 48 h on plate count agar. Scanning electron microscopy, light scattering by flow cytometry, and cell volume measurements were compared to evaluate the morphological changes in cells after pressurization. All these methods revealed that cellular morphology was not really affected. Esterase activity, as assessed either by enzymatic activity assays or by carboxy fluorescein diacetate fluorescence monitored by flow cytometry, was dramatically lowered, but not totally obliterated, under the effects of treatment. The measurement of propidium iodide uptake followed by flow cytometry demonstrated that membrane integrity was preserved in a small part of the population, although the membrane potential measured by analytical methods or evaluated by oxonol uptake was reduced from -86 to -5 mV. These results showed that such combined methods as fluorescent dyes monitored by flow cytometry and physiological activity measurements provide valuable indications of cellular viability.

  10. Energy balance in the solar transition region. I - Hydrostatic thermal models with ambipolar diffusion

    NASA Technical Reports Server (NTRS)

    Fontenla, J. M.; Avrett, E. H.; Loeser, R.

    1990-01-01

    The energy balance in the lower transition region is analyzed by constructing theoretical models which satisfy the energy balance constraint. The energy balance is achieved by balancing the radiative losses and the energy flowing downward from the corona. This energy flow is mainly in two forms: conductive heat flow and hydrogen ionization energy flow due to ambipolar diffusion. Hydrostatic equilibrium is assumed, and, in a first calculation, local mechanical heating and Joule heating are ignored. In a second model, some mechanical heating compatible with chromospheric energy-balance calculations is introduced. The models are computed for a partial non-LTE approach in which radiation departs strongly from LTE but particles depart from Maxwellian distributions only to first order. The results, which apply to cases where the magnetic field is either absent, or uniform and vertical, are compared with the observed Lyman lines and continuum from the average quiet sun. The approximate agreement suggests that this type of model can roughly explain the observed intensities in a physically meaningful way, assuming only a few free parameters specified as chromospheric boundary conditions.

  11. Compression of α-cristobalite under different hydrostatic conditions

    NASA Astrophysics Data System (ADS)

    Cernok, Ana; Marquardt, Katharina; Bykova, Elena; Liermann, Hanns-Peter; Dubrovinsky, Leonid

    2015-04-01

    The response of α-cristobalite to high-pressure has been a subject of numerous experimental and theoretical studies for more than two decades. The results indicated prolific polymorphism under high pressures, yet no consensus has emerged on what is the sequence of these pressure-induced transformations. In particular, the structure of the high-pressure polymorph that appears above ~10 GPa (hereafter cristobalite X-I), which is believed to be a direct link between the low-pressure (silicon in SiO4 tetrahedra) and the high-pressure (SiO6 octahedra) forms of silica remained elusive. This study examined the response of α-cristobalite when compressed at different levels of hydrostaticity, with the special focus on formation and stability of cristobalite X-I. The structural behavior of cristobalite under pressure was investigated up to ~80 GPa and at ambient temperature. We investigated behavior of single crystals and powders, in either (quasy)-hydrostatic or non-hydrostatic environment. In situ high pressure transformation path and structural behavior was studied by means of Raman spectroscopy and synchrotron X-ray diffraction (XRD). The samples recovered after pressure release were additionally investigated by transmission electron microscopy (TEM). Low- or α-cristobalite responds differently to high pressure depending on the degree of the hydrostaticity. The highest attainable hydrostaticity preserves the initial structure of cristobalite at least up to ~15 GPa. When the crystal experiences even slight stresses during an experiment, transformation sequence leads to cristobalite X-I - a monoclinic polymorph with silicon in octahedral coordination. This polymorph belongs to the family of the high-pressure silica phases that are comprised of distorted close-packed array of oxygen ions in which silicon atoms fully or partially occupy octahedral sites. The reflections collected on a single crystal at ~11 GPa can be indexed by a monoclinic unit cell a=6.658(9) Å, b=4

  12. A Two-Layer Model for Superposed Electrified Maxwell Fluids in Presence of Heat Transfer

    NASA Astrophysics Data System (ADS)

    Kadry, Zakaria; Magdy, A. Sirwah; Sameh, A. Alkharashi

    2011-06-01

    Based on a modified-Darcy—Maxwell model, two-dimensional, incompressible and heat transfer flow of two bounded layers, through electrified Maxwell fluids in porous media is performed. The driving force for the instability under an electric field, is an electrostatic force exerted on the free charges accumulated at the dividing interface. Normal mode analysis is considered to study the linear stability of the disturbances layers. The solutions of the linearized equations of motion with the boundary conditions lead to an implicit dispersion relation between the growth rate and wave number. These equations are parameterized by Weber number, Reynolds number, Marangoni number, dimensionless conductivities, and dimensionless electric potentials. The case of long waves interfacial stability has been studied. The stability criteria are performed theoretically in which stability diagrams are obtained. In the limiting cases, some previously published results can be considered as particular cases of our results. It is found that the Reynolds number plays a destabilizing role in the stability criteria, while the damping influence is observed for the increasing of Marangoni number and Maxwell relaxation time.

  13. The theory of quasi-geostrophic von Kármán vortex streets in two-layer fluids on a beta-plane

    NASA Astrophysics Data System (ADS)

    Gryanik, Vladimir M.; Borth, Hartmut; Olbers, Dirk

    2004-04-01

    In this study self-organized periodic coherent vortex structures arising in geophysical turbulent flows at low Rossby number are investigated by developing a conceptual model based on an analytical theory of von Kármán vortex streets affected by stratification and differential rotation. In the framework of a quasi-geostrophic (QG) two-layer beta-plane model vortex streets with three different types of vertical structures (barotropic, upper layer and hetonic) are analysed using the point vortex approximation. The streets are found to be exact solutions of the potential vorticity equation and to be characterized by four non-dimensional parameters. Von Kármán streets are semi-localized solutions which form a bridge between vortex pairs (limit of symmetric dilute streets) and two parallel vortex sheets (limit of dense streets). On the beta-plane QG von Kármán streets can only move to the east, i.e. with a speed outside the range of speeds of Rossby waves, so that a dynamical asymmetry in the zonal direction is introduced. A complete classification on a diagram of states shows that critical bounds exist in the parameter space, prescribing for example a maximum distance between vortex rows beyond which no QG vortex streets can be found. Typically a fast and a slow vortex street with different flow structures are found in the region of existence. As a function of distance between vortex rows baroclinic QG vortex streets show a characteristic non-monotonic speed behaviour at scales of the order of the baroclinic Rossby radius. A wide region of possible existence of QG von Kármán streets is found in atmospheric, oceanic and planetary conditions as well as in rotating tank experiments. The theory can be applied to describe the coherent part of turbulent baroclinic intermittent zonal jet-like and frontal flows and provides a scaling for such flows.

  14. An analysis of the 70-meter antenna hydrostatic bearing by means of computer simulation

    NASA Technical Reports Server (NTRS)

    Bartos, R. D.

    1993-01-01

    Recently, the computer program 'A Computer Solution for Hydrostatic Bearings with Variable Film Thickness,' used to design the hydrostatic bearing of the 70-meter antennas, was modified to improve the accuracy with which the program predicts the film height profile and oil pressure distribution between the hydrostatic bearing pad and the runner. This article presents a description of the modified computer program, the theory upon which the computer program computations are based, computer simulation results, and a discussion of the computer simulation results.

  15. Precipitation of anion inclusions and plasticity under hydrostatic pressure in II-VI crystals

    NASA Astrophysics Data System (ADS)

    Lindberg, G. P.; Weinstein, B. A.

    2016-10-01

    Precipitation of anion nanocrystals (NCs) in initially stoichiometric II-VI crystals under hydrostatic pressure and light exposure is explored by Raman spectroscopy, and the mechanism for this effect is analyzed by model calculations. ZnSe, ZnTe, and CdSe crystals are studied in bulk and/or epitaxial-film forms. Se and Te NCs in the trigonal (t) phase precipitate in ZnSe and ZnTe, but the effect is absent or minimal in CdSe. The precipitation is induced by pressure and assisted by sub-band-gap light. In ZnSe, t-Se NCs appear for pressure exceeding 4.8 GPa and light flux above 50 -70 W /m m2 . In ZnTe, the precipitation of t-Te NCs requires less pressure to initiate, and there is a clear upper-pressure limit for t-Te nuclei to form. We find also that ZnTe samples with cleavage damage or elevated zinc-vacancy content are more prone to form t-Te NCs at lower pressures (even 1 atm in some cases) and lower flux. The precipitation seen in ZnSe and ZnTe occurs at pressures far below their phase transitions, and cannot be due to those transitions. Rather, we propose that the NCs nucleate on dislocations that arise from hydrostatic-pressure induced plastic flow triggered by noncubic defect sites. Calculations of the kinetic barrier for growth of an optimally shaped nucleus are performed, including hydrostatic pressure in the energy minimization scheme. Using sensible values for the model parameters related to the cohesive energies of Se and Te, the calculations account for our main observations, including the existence of an upper pressure limit for precipitation, and the absence of precipitation in CdSe. We consider the effects of pressure-induced precipitate formation on the I-II phase transitions in a variety of binary semiconductors and make predictions of when this effect should be important.

  16. Assembly of two layered cobalt-molybdenum phosphates: Changing interlayer distances by tuning the lengths of amine ligands

    SciTech Connect

    Zhang Yunan; Zhou Baibin; Sha Jingquan; Su Zhanhua; Cui, Ji-Wen

    2011-02-15

    By using amines with different lengths, two layered cobalt-molybdenum phosphates with different interlayer distances, (C{sub 2}N{sub 2}H{sub 10}) [HCo(H{sub 2}O){sub 2}P{sub 2}MoO{sub 10}] (1), and (C{sub 3}N{sub 2}H{sub 12}){sub 4{l_brace}}Co{sub 3} [P{sub 4}Mo{sub 6}O{sub 26}(OH){sub 5}]{sub 2{r_brace}}. 5H{sub 2}O (2), have been hydrothermally synthesized and characterized. In compound 1, the H{sub 2}en direct the [CoMoP{sub 2}] clusters to form a layered framework. By changing the lengths of protonated organic amines (H{sub 2}en to 1, 3-H{sub 2}pn), compound 2 is obtained, in which the sandwich-shaped [Co (Mo{sub 6}P{sub 4}){sub 2}] clusters are linked by tetrahedrally coordinated cobalt into a layered framework. With the lengths of protonated organic amines increasing, the interlayer distances in compound 2 become larger. This work successfully demonstrates that tuning the lengths and conformation of the protonated organic amines can provide a facile route for the formation of organically templated inorganic open-framework materials. Additionally, susceptibility measurement shows that the two compounds both exhibit antiferromagnetic interactions. -- Graphical abstract: By using amines with different lengths, two layered cobalt-molybdenum phosphates with different interlayer distances have been hydrothermally synthesized. Display Omitted Research highlights: {yields} Two layered compounds have been synthesized by utilizing amines with different lengths. {yields} The chain lengths of amines can influence the overall supramolecular framework of the PMo-TMCs. {yields} The conformation of amines may influence the stacking mode of the inorganic building blocks. {yields} Susceptibility measurement shows that the two compounds both exhibit antiferromagnetic interactions.

  17. Efficient and stable proton acceleration by irradiating a two-layer target with a linearly polarized laser pulse

    NASA Astrophysics Data System (ADS)

    Wang, H. Y.; Yan, X. Q.; Chen, J. E.; He, X. T.; Ma, W. J.; Bin, J. H.; Schreiber, J.; Tajima, T.; Habs, D.

    2013-01-01

    We report an efficient and stable scheme to generate ˜200 MeV proton bunch by irradiating a two-layer targets (near-critical density layer+solid density layer with heavy ions and protons) with a linearly polarized Gaussian pulse at intensity of 6.0×1020 W/cm2. Due to self-focusing of laser and directly accelerated electrons in the near-critical density layer, the proton energy is enhanced by a factor of 3 compared to single-layer solid targets. The energy spread of proton is also remarkably reduced. Such scheme is attractive for applications relevant to tumor therapy.

  18. A 3-D Finite-Volume Non-hydrostatic Icosahedral Model (NIM)

    NASA Astrophysics Data System (ADS)

    Lee, Jin

    2013-11-01

    The Nonhydrostatic Icosahedral Model (NIM) formulates the latest numerical innovation of the three-dimensional finite-volume control volume on the quasi-uniform icosahedral grid suitable for ultra-high resolution simulations. NIM's modeling goal is to improve numerical accuracy for weather and climate simulations as well as to utilize the state-of-art computing architecture such as massive parallel CPUs and GPUs to deliver routine high-resolution forecasts in timely manner. NIM uses innovations in model formulation similar to its hydrostatic version of the Flow-following Icosahedral Model (FIM) developed by Earth System Research Laboratory (ESRL) which has been tested and accepted for future use by the National Weather Service as part of their operational global prediction ensemble. Innovations from the FIM used in the NIM include: * A local coordinate system remapped spherical surface to plane for numerical accuracy (Lee and MacDonald, 2009), * Grid points in a table-driven horizontal loop that allow any horizontal point sequence (A.E. MacDonald et al., 2010), * Flux-Corrected Transport formulated on finite-volume operators to maintain conservative positive definite transport (J.-L, Lee, et al., 2010), * All differentials evaluated as finite-volume integrals around the cells, *Icosahedral grid optimization (Wang and Lee, 2011) NIM extends the two-dimensional finite-volume operators used in FIM into the three-dimensional finite-volume solvers designed to improve pressure gradient calculation and orographic precipitation over complex terrain. The NIM dynamical core has been successfully verified with various non-hydrostatic benchmark test cases such as warm bubble, density current, internal gravity wave, and mountain waves. Physical parameterizations have been incorporated into the NIM dynamic core and successfully tested with multimonth aqua-planet simulations. Recent results from NIM simulations will be presented at the Symposium.

  19. Feedback Regulation of Intracellular Hydrostatic Pressure in Surface Cells of the Lens

    PubMed Central

    Gao, Junyuan; Sun, Xiurong; White, Thomas W.; Delamere, Nicholas A.; Mathias, Richard T.

    2015-01-01

    In wild-type lenses from various species, an intracellular hydrostatic pressure gradient goes from ∼340 mmHg in central fiber cells to 0 mmHg in surface cells. This gradient drives a center-to-surface flow of intracellular fluid. In lenses in which gap-junction coupling is increased, the central pressure is lower, whereas if gap-junction coupling is reduced, the central pressure is higher but surface pressure is always zero. Recently, we found that surface cell pressure was elevated in PTEN null lenses. This suggested disruption of a feedback control system that normally maintained zero surface cell pressure. Our purpose in this study was to investigate and characterize this feedback control system. We measured intracellular hydrostatic pressures in mouse lenses using a microelectrode/manometer-based system. We found that all feedback went through transport by the Na/K ATPase, which adjusted surface cell osmolarity such that pressure was maintained at zero. We traced the regulation of Na/K ATPase activity back to either TRPV4, which sensed positive pressure and stimulated activity, or TRPV1, which sensed negative pressure and inhibited activity. The inhibitory effect of TRPV1 on Na/K pumps was shown to signal through activation of the PI3K/AKT axis. The stimulatory effect of TRPV4 was shown in previous studies to go through a different signal transduction path. Thus, there is a local two-legged feedback control system for pressure in lens surface cells. The surface pressure provides a pedestal on which the pressure gradient sits, so surface pressure determines the absolute value of pressure at each radial location. We speculate that the absolute value of intracellular pressure may set the radial gradient in the refractive index, which is essential for visual acuity. PMID:26536260

  20. Hydrostatic pressure studies of polyvinylidine fluoride (PVDF) and its copolymers

    SciTech Connect

    Samara, G.A.; Bauer, F.

    1987-01-01

    The frequency, temperature and hydrostatic pressure (less than or equal to10 kbar) dependences of the dielectric properties, molecular relaxations and phase transitions in PVDF and a copolymer with a 30% trifluorethylene were investigated. For the copolymer, both the ferroelectric transition (T/sub c/) and dynamic melting (T/sub m/) temperatures exhibit large increases with pressure. PVDF itself does not exhibit a T/sub c/ below T/sub m/, but its T/sub m/ also shows a large increase with pressure. The pressure and frequency dependences suggest an explanation for why it is possible to use these polymers as piezoelectric shock wave gauges to relatively high shock pressures.

  1. Pasteurization of food by hydrostatic high pressure: chemical aspects.

    PubMed

    Tauscher, B

    1995-01-01

    Food pasteurized by hydrostatic high pressure have already been marketed in Japan. There is great interest in this method also in Europe and USA. Temperature and pressure are the essential parameters influencing the state of substances including foods. While the influence of temperature on food has been extensively investigated, effects of pressure, also in combination with temperature, are attracting increasing scientific attention now. Processes and reactions in food governed by Le Chatelier's principle are of special interest; they include chemical reactions of both low- and macromolecular compounds. Theoretical fundamentals and examples of pressure affected reactions are presented.

  2. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    DOEpatents

    Hill, Mary Ann; Bingert, John F.; Bingert, Sherri A.; Thoma, Dan J.

    1998-01-01

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process.

  3. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    DOEpatents

    Hill, M.A.; Bingert, J.F.; Bingert, S.A.; Thoma, D.J.

    1998-09-08

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process. 5 figs.

  4. Dielectric breakdown field of strained silicon under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Kim, Chiho; Ramprasad, Rampi

    2017-09-01

    First-principles density functional theory calculations are used to reveal a quantitative relationship between the dielectric breakdown field and hydrostatic pressure of crystalline Si. The electronic band structure, phonon dispersion, and electron scattering rate are computed for pressures from 62.2 kbar (compressive) to -45.6 kbar (tensile) to estimate the rate of kinetic energy gain and loss for the electron. The theoretical dielectric breakdown fields are then determined using the von Hippel-Fröhlich criterion. Compressive stresses lead to a lower breakdown field, while significant increases in the dielectric breakdown field can be achieved by tensile stresses.

  5. Multicore MgB 2 wires made by hydrostatic extrusion

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Pachla, W.; Hušek, I.; Kulczyk, M.; Melišek, T.; Holúbek, T.; Diduszko, R.; Reissner, M.

    2008-12-01

    Seven-filament MgB2/Fe and MgB2/Nb/Cu wires have been made by in situ process using hydrostatic extrusion, drawing and two-axial drawing deformation into the wire size of 1.1 × 1.1 mm2. The conductors were sintered at 650 °C/0.5 h and studied in terms of field-dependent transport critical current density and thermal stability. XRD, SEM and EDX analysis were applied for structural characterization. Transport current property and compositional/structural differences are compared and discussed in connection to used powders and metallic materials.

  6. A technique to measure rotordynamic coefficients in hydrostatic bearings

    NASA Technical Reports Server (NTRS)

    Capaldi, Russell J.

    1993-01-01

    An experimental technique is described for measuring the rotordynamic coefficients of fluid film journal bearings. The bearing tester incorporates a double-spool shaft assembly that permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit. This configuration yields data that enables determination of the full linear anisotropic rotordynamic coefficient matrices. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Some results are presented for a four-recess, oil-fed hydrostatic journal bearing.

  7. Single-molecule imaging at high hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Vass, Hugh; Lucas Black, S.; Flors, Cristina; Lloyd, Diarmuid; Bruce Ward, F.; Allen, Rosalind J.

    2013-04-01

    Direct microscopic fluorescence imaging of single molecules can provide a wealth of mechanistic information, but up to now, it has not been possible under high pressure conditions, due to limitations in microscope pressure cell design. We describe a pressure cell window design that makes it possible to image directly single molecules at high hydrostatic pressure. We demonstrate our design by imaging single molecules of Alexa Fluor 647 dye bound to DNA, at 120 and 210 bar, and following their fluorescence photodynamics. We further show that the failure pressure of this type of pressure cell window can be in excess of 1 kbar.

  8. A technique to measure rotordynamic coefficients in hydrostatic bearings

    NASA Astrophysics Data System (ADS)

    Capaldi, Russell J.

    1993-11-01

    An experimental technique is described for measuring the rotordynamic coefficients of fluid film journal bearings. The bearing tester incorporates a double-spool shaft assembly that permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit. This configuration yields data that enables determination of the full linear anisotropic rotordynamic coefficient matrices. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Some results are presented for a four-recess, oil-fed hydrostatic journal bearing.

  9. Nonaxisymmetric incompressible hydrostatic pressure effects in radial face seals

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    A flat seal having an angular misalinement is analyzed, taking into account the radial variations in seal clearance. An analytical solution for axial force, tilting moment, and leakage is presented that covers the whole range from zero to full angular misalinement. Nonaxisymmetric hydrostatic pressures due to the radial variations in the film thickness have a considerable effect on seal stability. When the high pressure is on the outer periphery of the seal, both the axial force and the tilting moment are nonrestoring. The case of high-pressure seals where cavitation is eliminated is discussed, and the possibility of dynamic instability is pointed out.

  10. Hydrostatic pressure sensing with surface-core fibers

    NASA Astrophysics Data System (ADS)

    Osório, Jonas H.; Franco, Marcos A. R.; Cordeiro, Cristiano M. B.

    2015-09-01

    In this paper, we report the employment of surface-core fibers for hydrostatic pressure sensing. To our knowledge, this is the first demonstration of the use of these fibers for the referenced purpose. Theoretical simulations of the fiber structure were performed in order to estimate fiber phase and group birefringence values and its pressure sensitivity coefficient. In order to test fiber performance when acting as a pressure sensor, the same was placed in an polarimetric setup and its spectral response was measured. A sensitivity of 4.8 nm/MPa was achieved, showing good resemblance to the expected sensitivity value (4.6 nm/MPa).

  11. A two-layer structured PbI2 thin film for efficient planar perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Ying, Chao; Shi, Chengwu; Wu, Ni; Zhang, Jincheng; Wang, Mao

    2015-07-01

    In this paper, a two-layer structured PbI2 thin film was constructed by the spin-coating procedure using a 0.80 M PbI2 solution in DMF and subsequent close-spaced vacuum thermal evaporation using PbI2 powder as a source. The bottom PbI2 thin film was compact with a sheet-like appearance, parallel to the FTO substrate, and can be easily converted to a compact perovskite thin film to suppress the charge recombination of the electrons of the TiO2 conduction band and the holes of the spiro-OMeTAD valence band. The top PbI2 thin film was porous with nano-sheet arrays, perpendicular to the FTO substrate, and can be easily converted to a porous perovskite thin film to improve the hole migration from the perovskite to spiro-OMeTAD and the charge separation at the perovskite/spiro-OMeTAD interface. The planar perovskite solar cells based on the two-layer structured PbI2 thin film exhibited a photoelectric conversion efficiency of 11.64%, along with an open-circuit voltage of 0.90 V, a short-circuit photocurrent density of 19.29 mA cm-2 and a fill factor of 0.67.

  12. A two-layer structured PbI2 thin film for efficient planar perovskite solar cells.

    PubMed

    Ying, Chao; Shi, Chengwu; Wu, Ni; Zhang, Jincheng; Wang, Mao

    2015-07-28

    In this paper, a two-layer structured PbI2 thin film was constructed by the spin-coating procedure using a 0.80 M PbI2 solution in DMF and subsequent close-spaced vacuum thermal evaporation using PbI2 powder as a source. The bottom PbI2 thin film was compact with a sheet-like appearance, parallel to the FTO substrate, and can be easily converted to a compact perovskite thin film to suppress the charge recombination of the electrons of the TiO2 conduction band and the holes of the spiro-OMeTAD valence band. The top PbI2 thin film was porous with nano-sheet arrays, perpendicular to the FTO substrate, and can be easily converted to a porous perovskite thin film to improve the hole migration from the perovskite to spiro-OMeTAD and the charge separation at the perovskite/spiro-OMeTAD interface. The planar perovskite solar cells based on the two-layer structured PbI2 thin film exhibited a photoelectric conversion efficiency of 11.64%, along with an open-circuit voltage of 0.90 V, a short-circuit photocurrent density of 19.29 mA cm(-2) and a fill factor of 0.67.

  13. Modeling of PZT-induced Lamb wave propagation in structures by using a novel two-layer spectral finite element

    NASA Astrophysics Data System (ADS)

    Liu, Xiaotong; Zhou, Li; Ouyang, Qinghua

    2016-04-01

    This paper presents a novel two-layer spectral finite element model, consisting of PZT wafer and host structure, to simulate PZT-induced Lamb wave propagation in beam-like and plate-like structures. Based on the idea of equal displacement on the interface between PZT wafer and host structure, the one-dimensional spectral beam element of PZT-host beam and two-dimensional spectral plate element of PZT-host plate are considered as one hybrid element, respectively. A novel approach is proposed by taking the coupling effect of piezoelectric transducers in the thickness direction into account. The dynamic equation of the two-layer spectral element is derived from Hamilton's principle. Validity of the developed spectral finite element is verified through numerical simulation. The result indicates that, compared with the conventional finite element method (FEM) based on elasticity, the proposed spectral finite element is proved to have a high accuracy in modeling Lamb wave propagation, meanwhile, significantly improve the calculation efficiency.

  14. Gravity Currents Propagating Up a Slope in a Uniform Ambient and a Two-Layer Stratified Ambient Depth

    NASA Astrophysics Data System (ADS)

    Marleau, Larissa; Flynn, Morris; Sutherland, Bruce

    2014-11-01

    Bottom propagating gravity currents resulting from full- and partial-depth lock-release experiments are investigated as they propagate up a slope within a uniform and a two-layer stratified ambient. For the former case we adapt the theory of Shin et al. (J. Fluid Mech., 521, 2004) and derive a relationship for the deceleration of the front as a function of the slope angle and gravity current density. Experimental results show that the shape of the gravity current is self-similar as it decelerates over relatively steep slopes. The evolution of a gravity current in a two-layer ambient is complicated by the excitation of and interaction with a solitary wave. If the initial gravity current speed is subcritical to the wave speed, the current eventually stops abruptly while the wave continues at constant speed. If supercritical, turbulence at the current head is suppressed as it approaches the interface at the leading edge of the wave and the is re-established as the head becomes in direct contact with the upper layer.

  15. Measurement of small values of hydrostatic pressure difference / Pomiar małych wartości różnicy ciśnień hydrostatycznych

    NASA Astrophysics Data System (ADS)

    Broda, Krzysztof; Filipek, Wiktor

    2012-10-01

    In order to describe the fluid flow through the porous centre, made of identical spheres, it is necessary to know the pressure, but in fact - the pressure distribution. For the flows in the range that was traditionally called laminar flow (i. e. for Reynolds numbers (Bear, 1988; Duckworth, 1983; Troskolański, 1957) from the range 0,01 to 3) it is virtually impossible with the use of the tools directly available on the market. Therefore, many scientists who explore this problem have concentrated only on the research of the velocity distribution of the medium that penetrates the intended centre (Bear, 1988) or pressure distribution at high hydraulic gradients (Trzaska & Broda, 1991, 2000; Trzaska et al., 2005). It may result from the inaccessibility to the measurement methods that provide measurement of very low hydrostatic pressures, such as pressure resulting from the weight of liquid located in the gravitational field (Duckworth, 1983; Troskolański, 1957). The pressure value c. 10 Pa (Troskolański, 1957) can be generated even by 1 mm height difference between the two levels of the free water surface, which in fact constitutes the definition of gauging tools of today measuring the level of the hydrostatic pressure. Authors proposed a method of hydrostatic pressure measurement and devised a gauging tool. Then a series of tests was conducted aiming at establishing what is the influence of various factors, such as temperature, atmospheric pressure, velocity of measurement completion, etc. on the accuracy and method of measurements. A method for considerable reduction of hysteresis that occurs during measurement was also devised. The method of measurement of small hydrostatic difference measurements allows for the accuracy of measurement of up to 0.5 Pa. Measurement results can be improved successfully by one order of magnitude, which for sure would entail necessary temperature stabilization of the tool. It will be more difficult though to compensate the influence

  16. Opportunities of hydrostatically coupled dielectric elastomer actuators for haptic interfaces

    NASA Astrophysics Data System (ADS)

    Carpi, Federico; Frediani, Gabriele; De Rossi, Danilo

    2011-04-01

    As a means to improve versatility and safety of dielectric elastomer actuators (DEAs) for several fields of application, so-called 'hydrostatically coupled' DEAs (HC-DEAs) have recently been described. HC-DEAs are based on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load, so as to enable hydrostatic transmission. This paper presents ongoing developments of HC-DEAs and potential applications in the field of haptics. Three specific examples are considered. The first deals with a wearable tactile display used to provide users with tactile feedback during electronic navigation in virtual environments. The display consists of HCDEAs arranged in contact with finger tips. As a second example, an up-scaled prototype version of an 8-dots refreshable cell for dynamic Braille displays is shown. Each Braille dot consists of a miniature HC-DEA, with a diameter lower than 2 mm. The third example refers to a device for finger rehabilitation, conceived to work as a sort of active version of a rehabilitation squeezing ball. The device is designed to dynamically change its compliance according to an electric control. The three examples of applications intend to show the potential of the new technology and the prospective opportunities for haptic interfaces.

  17. Study of glass hydrometer calibration by hydrostatic weighting

    NASA Astrophysics Data System (ADS)

    Chen, Chaoyun; Wang, Jintao; Li, Zhihao; Zhang, Peiman

    2016-01-01

    Glass hydrometers are simple but effective instruments for measuring the density of liquids. Glass hydrometers calibration based on the Archimedes law, using silicon ring as a reference standard solid density, n-tridecane with density stability and low surface tension as the standard working liquid, based on hydrostatic weighing method designs a glass hydrometer calibration system. Glass hydrometer calibration system uses CCD image measurement system to align the scale of hydrometer and liquid surface, with positioning accuracy of 0.01 mm. Surface tension of the working liquid is measured by Whihemy plate. According to twice glass hydrometer weighing in the air and liquid can calculate the correction value of the current scale. In order to verify the validity of the principle of the hydrostatic weighing method of glass hydrometer calibration system, for measuring the density range of (770-790) kg/m3, with a resolution of 0.2 kg/m3 of hydrometer. The results of measurement compare with the Physikalisch-Technische Bundesanstalt(PTB) ,verifying the validity of the calibration system.

  18. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    DOE PAGES

    Chambliss, K.; Diwan, M.; Simos, N.; ...

    2014-10-09

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack, and an average velocity was determined for allmore » measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.« less

  19. Photomultiplier tube failure under hydrostatic pressure in future neutrino detectors

    SciTech Connect

    Chambliss, K.; Diwan, M.; Simos, N.; Sundaram, S. K.

    2014-10-09

    Failure of photomultiplier tubes (PMTs) under hydrostatic pressure is a concern in neutrino detection, specifically, in the proposed Long-Baseline Neutrino Experiment project. Controlled hydrostatic implosion tests were performed on prototypic PMT bulbs of 10-inch diameter and recorded using high speed filming techniques to capture failures in detail. These high-speed videos were analyzed frame-by-frame in order to identify the origin of a crack, measure the progression of individual crack along the surface of the bulb as it propagates through the glass, and estimate crack velocity. Crack velocity was calculated for each individual crack, and an average velocity was determined for all measurable cracks on each bulb. Overall, 32 cracks were measured in 9 different bulbs tested. Finite element modeling (FEM) of crack formation and growth in prototypic PMT shows stress concentration near the middle section of the PMT bulbs that correlates well with our crack velocity measurements in that section. The FEM model predicts a crack velocity value that is close to the terminal crack velocity reported. Our measurements also reveal significantly reduced crack velocities compared to terminal crack velocities measured in glasses using fracture mechanics testing and reported in literature.

  20. Meso-NH: Non-hydrostatic mesoscale atmospheric model

    NASA Astrophysics Data System (ADS)

    Laboratoire d'Aérologie; Centre National de Recherches Météorologiques

    2016-12-01

    Meso-NH is the non-hydrostatic mesoscale atmospheric model of the French research community jointly developed by the Laboratoire d'Aérologie (UMR 5560 UPS/CNRS) and by CNRM (UMR 3589 CNRS/Météo-France). Meso-NH incorporates a non-hydrostatic system of equations for dealing with scales ranging from large (synoptic) to small (large eddy) scales while calculating budgets and has a complete set of physical parameterizations for the representation of clouds and precipitation. It is coupled to the surface model SURFEX for representation of surface atmosphere interactions by considering different surface types (vegetation, city, ocean, lake) and allows a multi-scale approach through a grid-nesting technique. Meso-NH is versatile, vectorized, parallelized, and operates in 1D, 2D or 3D; it is coupled with a chemistry module (including gas-phase, aerosol, and aqua-phase components) and a lightning module, and has observation operators that compare model output directly with satellite observations, radar, lidar and GPS.

  1. DX centers in III-V semiconductors under hydrostatic pressure

    SciTech Connect

    Wolk, Jeffrey Alan

    1992-11-01

    DX centers are deep level defects found in some III-V semiconductors. They have persistent photoconductivity and large difference between thermal and optical ionization energies. Hydrostatic pressure was used to study microstructure of these defects. A new local vibrational mode (LVM) was observed in hydrostatically stressed, Si-doped GaAs. Corresponding infrared absorption peak is distinct from the SiGa shallow donor LVM peak, which is the only other LVM peak observed in our samples, and is assigned to the Si DX center. Analysis of the relative intensities of the Si DX LVM and the Si shallow donor LVM peaks, combined with Hall effect and resistivity indicate that the Si DX center is negatively charged. Frequency of this new mode provides clues to the structure of this defect. A pressure induced deep donor level in S-doped InP was also discovered which has the properties of a DX center. Pressure at which the new defect becomes more stable than the shallow donor is 82 kbar. Optical ionization energy and energy dependence of the optical absorption cross section was measured for this new effect. Capture barrier from the conduction band into the DX state were also determined. That DX centers can be formed in InP by pressure suggests that DX states should be common in n-type III-V semiconductors. A method is suggested for predicting under what conditions these defects will be the most stable form of the donor impurity.

  2. Collapse of composite tubes under uniform external hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Smith, P. T.; Ross, C. T. F.; Little, A. P. F.

    2009-08-01

    This paper describes an experimental and a theoretical investigation into the collapse of 22 circular cylindrical composite tubes under external hydrostatic pressure. The investigations were on the collapse of fibre reinforced plastic tube specimens made from a mixture of three carbon and two E-glass fibre layers. The theoretical investigations were carried out using an in-house finite element computer program called BCLAM, together with the commercial computer package, namely ANSYS. It must be emphasised here that BS 5500 does not appear to exclusively cater for the buckling of composite shells under external hydrostatic pressure, so the work presented here is novel and should be useful to industry. The experimental investigations showed that the composite specimens behaved similarly to isotropic materials previously tested, in that the short vessels collapsed through axisymmetric deformation while the longer tubes collapsed through non-symmetric bifurcation buckling. Furthermore it was discovered that the models failed at changes of the composite lay-up due to the manufacturing process of these models. These changes seemed to be the weak points of the specimens.

  3. L1448 IRS2E: A CANDIDATE FIRST HYDROSTATIC CORE

    SciTech Connect

    Chen Xuepeng; Arce, Hector G.; Zhang Qizhou; Bourke, Tyler L.; Launhardt, Ralf; Schmalzl, Markus; Henning, Thomas

    2010-06-01

    Intermediate between the prestellar and Class 0 protostellar phases, the first core is a quasi-equilibrium hydrostatic object with a short lifetime and an extremely low luminosity. Recent magnetohydrodynamic (MHD) simulations suggest that the first core can even drive a molecular outflow before the formation of the second core (i.e., protostar). Using the Submillimeter Array and the Spitzer Space Telescope, we present high angular resolution observations toward the embedded dense core IRS2E in L1448. We find that source L1448 IRS2E is not visible in the sensitive Spitzer infrared images (at wavelengths from 3.6 to 70 {mu}m) and has weak (sub-) millimeter dust continuum emission. Consequently, this source has an extremely low bolometric luminosity (<0.1 L {sub sun}). Infrared and (sub-) millimeter observations clearly show an outflow emanating from this source; L1448 IRS2E represents thus far the lowest luminosity source known to be driving a molecular outflow. Comparisons with prestellar cores and Class 0 protostars suggest that L1448 IRS2E is more evolved than prestellar cores but less evolved than Class 0 protostars, i.e., at a stage intermediate between prestellar cores and Class 0 protostars. All these results are consistent with the theoretical predictions of the radiative/MHD simulations, making L1448 IRS2E the most promising candidate of the first hydrostatic core revealed so far.

  4. The tensile deformation behavior of nuclear-grade isotropic graphite posterior to hydrostatic loading

    NASA Astrophysics Data System (ADS)

    Yoda, S.; Eto, M.

    1983-10-01

    The effects of prehydrostatic loading on microstructural changes and tensile deformation behavior of nuclear-grade isotropic graphite have been examined. Scanning electron micrographs show that formation of microcracks associated with delamination between basal planes occurs under hydrostatic loading. Hydrostatic loading on specimens results in the decrease in tensile strength and increase in residual strain generated by the applied tensile stress at various levels, indicating that the graphite material is weakened by hydrostatic loading. A relationship between residual strain and applied tensile stress for graphite hydrostatically-loaded at several pressure levels can be approximately expressed as ɛ = ( AP + B) σn over a wide range hydrostatic pressure, where ɛ, P and σ denote residual strain, hydrostatic pressure and applied tensile stress, respectively; A, B and n are constants. The effects of prehydrostatic loading on the tensile stress-strain behavior of the graphite were examined in more detail. The ratio of stress after hydrostatic loading to that before hydrostatic loading on the stress-strain relationship remains almost unchanged irrespective of strain.

  5. Development of methods and equipment for bellows assemblies testing under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Ol'khovik, E.

    2016-04-01

    The paper presents a newbellows assemblies test method for stop and safety valves. To create the real conditions it is suggested testing under external hydrostatic pressure, which is available in the piping system.A designed test apparatus allows testing of the bellows under the effect of external hydrostatic pressure. The paper describes the design of the apparatus, its specifications and the test procedures.

  6. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... exceed the maximum test pressure of any component such as vessels, pumps, or valves in the system. (2) At... SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of... system is filling. (b) Test medium and test temperature. (1) Water will be used for a hydrostatic...

  7. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... exceed the maximum test pressure of any component such as vessels, pumps, or valves in the system. (2) At... SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of... system is filling. (b) Test medium and test temperature. (1) Water will be used for a hydrostatic...

  8. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... exceed the maximum test pressure of any component such as vessels, pumps, or valves in the system. (2) At... SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of... system is filling. (b) Test medium and test temperature. (1) Water will be used for a hydrostatic...

  9. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... exceed the maximum test pressure of any component such as vessels, pumps, or valves in the system. (2) At... SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of... system is filling. (b) Test medium and test temperature. (1) Water will be used for a hydrostatic...

  10. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... exceed the maximum test pressure of any component such as vessels, pumps, or valves in the system. (2) At... SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of... system is filling. (b) Test medium and test temperature. (1) Water will be used for a hydrostatic...

  11. Numerical studies on the dynamics of two-layer Rayleigh-Bénard convection with an infinite Prandtl number and large viscosity contrasts

    NASA Astrophysics Data System (ADS)

    Yoshida, Masaki; Hamano, Yozo

    2016-11-01

    The fundamental physics and dynamics relating to two-layer convection with an infinite Prandtl number and large viscosity contrasts have not yet been quantitatively resolved by previous numerical analyses or simulations and laboratory experiments. Here, a series of high-resolution numerical simulations of Rayleigh-Bénard convection with a highly viscous outer layer (HVL) and a low-viscosity inner layer (LVL) in 2-D spherical-shell geometry were performed to investigate the dynamics of convection between the two layers with large viscosity contrasts of up to 103. To achieve a two-layer thermal convection system considering a thermally and mechanically continuous interface between the two layers without any specified boundary conditions, an "effective thermal expansion coefficient" was introduced to the buoyancy term of the momentum equation, discretized in a finite-volume-based regular grid system. In this study, the heat transport efficiency of two-layer convection was evaluated, and the coupling modes between the two layers were directly analyzed using the temperature anomaly and deviatoric stress fields near the interface. Results show that the mechanical coupling mode is dominant in two-layer convection when the absolute viscosity contrast between the two layers is sufficiently small, and it weakens, becoming closer to the thermal coupling mode, as the LVL viscosity decreases. This transition from the mechanical coupling to the thermal coupling modes is quantitatively detected even when the viscosity contrast between the two layers is 10-3, and results in the stabilizing of the convection speed and the heat transport efficiency of the HVL. Applying the mantle-outer core coupling of the present Earth with an extremely large absolute viscosity contrast, our numerical results imply that thermal convection in the mantle may control the heat transport efficiency of a layered whole solid-earth system and the convective style in the outer core.

  12. The Importance of Modeling Non-hydrostatic Processes for Dense Water Reproduction in the Southern Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Bellafiore, Debora; Mc Kiver, William; Umgiesser, Georg

    2017-04-01

    In this work we use high-resolution numerical simulations to investigate how non-hydrostatic processes affect the propagation and dynamics of dense water along the margins of the Adriatic Sea to its southern end. Dense water formation commonly occurs in the shallow Northern Adriatic during Bora wind outbreaks, as a consequence of the combination of the cooling of surface waters by the cold winds and the salinity increase due to the reduced river inputs. These dense waters subsequently propagate southwards, following the shallow pathway along the Italian coast, over a period of weeks/months, eventually arriving in the Southern Adriatic Sea. The investigation is based on a new non-hydrostatic formulation of the 3D finite element model SHYFEM that has been checked with theoretical test cases and validated for the Adriatic Sea implementation. Results provide good agreement with the analytical solutions of test cases and good matches for the main hydrodynamic variables are obtained from the validation with measurements collected in the field campaign of March-April 2012 done in the South Adriatic. The increased spatial resolution kept at the shelf border in the Southern Adriatic, in the so called Bari Canyon System, allowed for a thorough investigation of the spill of dense water, which break geostrophic balance, finding specific cascading pathways into the South Adriatic Pit. Interactions between the semi-enclosed basins large scale general circulation and the more local patterns due to the passage of dense water are discussed, in order to clarify the model capability to reproduce these processes within the existing modeling limits. The new non-hydrostatic formulation of the code allows us to identify the gravity flow from the shelf along the slope to the deepest areas of the basin, modulating the energy transfer between the shallow coast and the deep sea.

  13. A two-layer diagnostic model of the long-term physical evolution of warm-core ring 82B

    NASA Technical Reports Server (NTRS)

    Olson, D. B.; Schmitt, R. W.; Kennelly, M.; Joyce, T. M.

    1985-01-01

    The present shipboard data in the 1982 time series on a single Gulf Stream warm core ring are composited on a cylindrical coordinate system following ring motion; 10 C-isotherm depth measurements are used in a two-layer model of the ring's structure to compute gradient current, kinetic energy, available potential energy (APE), and potential vorticity. The ring's evolution can be divided into two periods: April-late June, while the ring is isolated from strong Gulf Stream interaction, during which the ring loses APE at a low rate, and from July onward, following ring interactions with the Gulf Stream and topography with much higher energy loss. Within measurement errors, the potential vorticity at the center of the ring is conserved from April through August, implying nearly inviscid dynamics.

  14. Modeling Marine Boundary-Layer Clouds with a Two-Layer Model: A One-Dimensional Simulation.

    NASA Astrophysics Data System (ADS)

    Wang, Shouping

    1993-12-01

    A two-layer model of the marine boundary layer is described. The model is used to simulate both stratocumulus and shallow cumulus clouds in downstream simulations. Over cold sea surfaces, the model predicts a relatively uniform structure in the boundary layer with 90%-100% cloud fraction. Over warm sea surfaces, the model predicts a relatively strong decoupled and conditionally unstable structure with a cloud fraction between 30% and 60%. A strong large-scale divergence considerably limits the height of the boundary layer and decreases relative humidity in the upper part of the cloud layer; thus, a low cloud fraction results. The effects of drizzle on the boundary-layer structure and cloud fraction are also studied with downstream simulations. It is found that drizzle dries and stabilizes the cloud layer and tends to decouple the cloud from the subcloud layer. Consequently, solid stratocumulus clouds may break up and the cloud fraction may decrease because of drizzle.

  15. Novel bending-resistant design of two-layer low-index trench fiber with parabolic-profile core.

    PubMed

    Sun, Jiang; Kang, Zexin; Wang, Jing; Liu, Chao; Jian, Shuisheng

    2014-07-28

    A novel design, two-layer low-index trench fiber with parabolic-profile core, is proposed and investigated numerically in this paper. Based on scalar FD-BPM algorithm, the excellent performance over other types of structures and great potential in mode area enlargement are demonstrated. The effective mode area of our design (D = 100μm) is approximately 890 μm2. Both the high order mode (HOM) suppression and bending resistance of our design are better than that of Multi-Trench Fiber (MTF). The mode loss ratio and effective mode area are independent on the bending radius. Due to the circular symmetry of our proposed configuration design, the bending property is not varied with the changing of bending directions.

  16. Two-layer optical model of skin for early, non-invasive detection of wound development on the diabetic foot

    NASA Astrophysics Data System (ADS)

    Yudovsky, Dmitry; Nouvong, Aksone; Schomacker, Kevin; Pilon, Laurent

    2010-02-01

    Foot ulceration is a debilitating comorbidity of diabetes that may result in loss of mobility and amputation. Optical detection of cutaneous tissue changes due to inflammation and necrosis at the preulcer site could constitute a preventative strategy. A commercial hyperspectral oximetry system was used to measure tissue oxygenation on the feet of diabetic patients. A previously developed predictive index was used to differentiate preulcer tissue from surrounding healthy tissue with a sensitivity of 92% and specificity of 80%. To improve prediction accuracy, an optical skin model was developed treating skin as a two-layer medium and explicitly accounting for (i) melanin content and thickness of the epidermis, (ii) blood content and hemoglobin saturation of the dermis, and (iii) tissue scattering in both layers. Using this forward model, an iterative inverse method was used to determine the skin properties from hyperspectral images of preulcerative areas. The use of this information in lowering the false positive rate was discussed.

  17. Multi-frequency based location search algorithm of small electromagnetic inhomogeneities embedded in two-layered medium

    NASA Astrophysics Data System (ADS)

    Park, Won-Kwang; Park, Taehoon

    2013-07-01

    In this paper, we consider a problem for finding the locations of electromagnetic inhomogeneities completely embedded in homogeneous two layered medium. For this purpose, we present a filter function operated at several frequencies and design an algorithm for finding the locations of such inhomogeneities. It is based on the fact that, the collected Multi-Static Response (MSR) matrix can be modeled via a rigorous asymptotic expansion formula of the scattering amplitude due to the presence of such inhomogeneities. In order to show the effectiveness, we compare the proposed algorithm with traditional MUltiple SIgnal Classification (MUSIC) algorithm and Kirchhoff migration. Various numerical results demonstrate that the proposed algorithm is robust with respect to random noise and yields more accurate location than the MUSIC algorithm and Kirchhoff migration.

  18. A two-layer diagnostic model of the long-term physical evolution of warm-core ring 82B

    NASA Technical Reports Server (NTRS)

    Olson, D. B.; Schmitt, R. W.; Kennelly, M.; Joyce, T. M.

    1985-01-01

    The present shipboard data in the 1982 time series on a single Gulf Stream warm core ring are composited on a cylindrical coordinate system following ring motion; 10 C-isotherm depth measurements are used in a two-layer model of the ring's structure to compute gradient current, kinetic energy, available potential energy (APE), and potential vorticity. The ring's evolution can be divided into two periods: April-late June, while the ring is isolated from strong Gulf Stream interaction, during which the ring loses APE at a low rate, and from July onward, following ring interactions with the Gulf Stream and topography with much higher energy loss. Within measurement errors, the potential vorticity at the center of the ring is conserved from April through August, implying nearly inviscid dynamics.

  19. Two-layer observer based control for a class of uncertain systems with multi-frequency disturbances.

    PubMed

    Wen, Xinyu; Yan, Peng

    2016-07-01

    A novel disturbance estimation approach is presented for a class of uncertain systems subject to multiple-sinusoidal disturbances with unknown frequencies. Different from existing results on disturbance observer based control (DOBC), a new methodology with a two-layer observer structure is developed to effectively estimate and reject the disturbances. In the proposed control architecture, an auxiliary observer is derived to generate a disturbance representation in a parametric uncertainty form. Furthermore, the unknown parameters can be reduced to a constant vector with the dimension of the number of harmonic components in the disturbances. Then an augmented observer is designed to estimate the corresponding unknown parameters of the disturbances. As a result, the uncertain systems with disturbances constituting of multiple unknown-frequency sinusoidal components can be controlled within the DOBC framework, where asymptotic stability can be guaranteed. The proposed approach is successfully validated on a robotic manipulating example.

  20. Identification of a Segment of the Yield Surface of a Two-Layer Pa38/M2R Composite

    NASA Astrophysics Data System (ADS)

    Uscinowicz, R. R.

    2016-05-01

    The aim of this study was to identify the initial yield surface of a two-layer aluminum alloy-copper composite in the range of small elastic-plastic deformations. Experimental tests in a plane stress state were conducted by loading tubular composite specimens with various combinations of axial forces and torque. The metal layers were joined together by using an epoxy resin. Independent studies were carried out for component of the composite under identical conditions. The yield surfaces obtained were compared with those given by the Huber-von Mises-Hencky and Tresca-Guest yield criteria. The yield criterion for the tested composite found by using a modified form of the rule of mixtures is presented. The yield surfaces of a Pa38/M2R composite and its components demonstrated the isotropic hardening.

  1. Monte carlo diffusion hybrid model for photon migration in a two-layer turbid medium in the frequency domain.

    PubMed

    Alexandrakis, G; Farrell, T J; Patterson, M S

    2000-05-01

    We propose a hybrid Monte Carlo (MC) diffusion model for calculating the spatially resolved reflectance amplitude and phase delay resulting from an intensity-modulated pencil beam vertically incident on a two-layer turbid medium. The model combines the accuracy of MC at radial distances near the incident beam with the computational efficiency afforded by a diffusion calculation at further distances. This results in a single forward calculation several hundred times faster than pure MC, depending primarily on model parameters. Model predictions are compared with MC data for two cases that span the extremes of physiologically relevant optical properties: skin overlying fat and skin overlying muscle, both in the presence of an exogenous absorber. It is shown that good agreement can be achieved for radial distances from 0.5 to 20 mm in both cases. However, in the skin-on-muscle case the choice of model parameters and the definition of the diffusion coefficient can lead to some interesting discrepancies.

  2. Lookup-table-based inverse model for human skin reflectance spectroscopy: two-layered Monte Carlo simulations and experiments.

    PubMed

    Zhong, Xiewei; Wen, Xiang; Zhu, Dan

    2014-01-27

    Fiber reflectance spectroscopy is a non-invasive method for diagnosing skin diseases or evaluating aesthetic efficacy, but it is dependent on the inverse model validity. In this work, a lookup-table-based inverse model is developed using two-layered Monte Carlo simulations in order to extract the physiological and optical properties of skin. The melanin volume fraction and blood oxygen parameters are extracted from fiber reflectance spectra of in vivo human skin. The former indicates good coincidence with a commercial skin-melanin probe, and the latter (based on forearm venous occlusion and ischemia, and hot compress experiment) shows that the measurements are in agreement with physiological changes. These results verify the potential of this spectroscopy technique for evaluating the physiological characteristics of human skin.

  3. Two-layer anti-reflection coating with mullite and polyimide foam for large-diameter cryogenic infrared filters.

    PubMed

    Inoue, Yuki; Hamada, Takaho; Hasegawa, Masaya; Hazumi, Masashi; Hori, Yasuto; Suzuki, Aritoki; Tomaru, Takayuki; Matsumura, Tomotake; Sakata, Toshifumi; Minamoto, Tomoyuki; Hirai, Tohru

    2016-12-01

    We have developed a novel two-layer anti-reflection (AR) coating method for large-diameter infrared (IR) filters made of alumina, for use at cryogenic temperatures in millimeter wave measurements. Thermally sprayed mullite and polyimide foam (Skybond Foam) are used as the AR material. An advantage of the Skybond Foam is that the index of refraction is chosen between 1.1 and 1.7 by changing the filling factor. Combination with mullite is suitable for wide-band millimeter wave measurements with sufficient IR cutoff capability. We present the material properties, fabrication of a large-diameter IR filter made of alumina with this AR coating method, and characterizations at cryogenic temperatures. This technology can be applied to a low-temperature receiver system with a large-diameter focal plane for next-generation cosmic microwave background polarization measurements, such as POLARBEAR-2 (PB-2).

  4. Efficient and stable proton acceleration by irradiating a two-layer target with a linearly polarized laser pulse

    SciTech Connect

    Wang, H. Y.; Yan, X. Q.; Chen, J. E.; He, X. T.; Ma, W. J.; Bin, J. H.; Schreiber, J.; Tajima, T.; Habs, D.

    2013-01-15

    We report an efficient and stable scheme to generate {approx}200 MeV proton bunch by irradiating a two-layer targets (near-critical density layer+solid density layer with heavy ions and protons) with a linearly polarized Gaussian pulse at intensity of 6.0 Multiplication-Sign 10{sup 20} W/cm{sup 2}. Due to self-focusing of laser and directly accelerated electrons in the near-critical density layer, the proton energy is enhanced by a factor of 3 compared to single-layer solid targets. The energy spread of proton is also remarkably reduced. Such scheme is attractive for applications relevant to tumor therapy.

  5. Residual currents over a uniform slope due to breaking of internal waves in a two-layer system

    NASA Astrophysics Data System (ADS)

    Nakayama, Keisuke; Shintani, Tetsuya; Kokubo, Kazuki; Kakinuma, Taro; Maruya, Yasuyuki; Komai, Katsuaki; Okada, Tomonari

    2012-10-01

    Residual currents due to internal wave breaking on a uniform slope were investigated in a two-layer system using laboratory experiments and numerical computations for different layer configurations. Internal wave-induced currents over a slope were measured in an experimental tank using PIV and also reproduced by a hydrodynamic model to quantify the detailed velocity field. The present results reveal that the critical level derived from the KdV theorem is a useful parameter for classifying the dynamics of internal waves breaking over a slope. As the horizontal distance from the critical level point to the internal wave breaking point increases, internal waves break more dynamically over the slope. Consequently, residual currents are enhanced near the breaking point. These findings increase our capacity to understand flux paths of biological and chemical substances in the stratified coastal ocean.

  6. Synthesis and absorbing mechanism of two-layer microwave absorbers containing polycrystalline iron fibers and carbonyl iron

    NASA Astrophysics Data System (ADS)

    Ding, Qingwei; Zhang, Mingang; Zhang, Cunrui; Qian, Tianwei

    2013-04-01

    Polycrystalline iron fibers were fabricated by α-FeOOH fiber precursors. Two-layer microwave absorber had been prepared by as-prepared polycrystalline iron fibers and carbonyl iron. The structure, morphology and properties of the composites were characterized with X-ray diffraction, scanning electron microscope and Network Analyzer. The complex permittivity and reflection loss (dB) of the composites were measured employing vector network analyzer model PNA 3629D vector in the frequency range between 30 and 6000 MHz. The thickness effect of the carbonyl iron layer on the microwave loss properties of the composites was investigated. A possible microwave-absorbing mechanism of polycrystalline iron fibers/carbonyl iron composite was proposed. The polycrystalline iron fibers/carbonyl iron composite can find applications in suppression of electromagnetic interference, and reduction of radar signature.

  7. Effects of high hydrostatic pressure on emulsifying properties of sweet potato protein in model protein-hydrocolloids system.

    PubMed

    Khan, Nasir Mehmood; Mu, Tai-Hua; Ali, Farman; Arogundade, Lawrence A; Khan, Zia Ullah; Zhang, Maio; Ahmad, Shujaat; Sun, Hong-Nan

    2015-02-15

    The effects of high hydrostatic pressure (HHP) on emulsifying properties of sweet potato protein (SPP) in presence of 0.1%, 0.3% and 0.5% (w/v) of guar gum (GG) and glycerol monostearate (GMS) were investigated. Emulsifying stability index (ESI) of the SPP with GG revealed significant increase (P<0.05) in ESI value at 600MPa treatment, while the stability of SPP-GMS emulsions significantly decreased with increase in GMS concentrations and HHP treatments (200-600MPa). HHP treatment considerably reduced the creaming rate for SPP-GG model while such case was not observed for SPP-GMS model. The flow index for SPP-GG emulsion model was found to decrease with increase in HHP treatment and had non-Newtonian behaviour. The SPP-GMS emulsion models with HHP treatments showed comparatively lower viscosities but had more Newtonian flow character. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Dynamic Culturing of Cartilage Tissue: The Significance of Hydrostatic Pressure

    PubMed Central

    Pereira, Ana L.; Duarte, Ana R.C.; Frias, Ana M.; Pedro, Adriano J.; Oliveira, João T.; Sousa, Rui A.; Reis, Rui L.

    2012-01-01

    Human articular cartilage functions under a wide range of mechanical loads in synovial joints, where hydrostatic pressure (HP) is the prevalent actuating force. We hypothesized that the formation of engineered cartilage can be augmented by applying such physiologic stimuli to chondrogenic cells or stem cells, cultured in hydrogels, using custom-designed HP bioreactors. To test this hypothesis, we investigated the effects of distinct HP regimens on cartilage formation in vitro by either human nasal chondrocytes (HNCs) or human adipose stem cells (hASCs) encapsulated in gellan gum (GG) hydrogels. To this end, we varied the frequency of low HP, by applying pulsatile hydrostatic pressure or a steady hydrostatic pressure load to HNC-GG constructs over a period of 3 weeks, and evaluated their effects on cartilage tissue-engineering outcomes. HNCs (10×106 cells/mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 3 weeks: (1) 0.4 MPa Pulsatile HP; (2) 0.4 MPa Steady HP; and (3) Static. Subsequently, we applied the pulsatile regimen to hASC-GG constructs and varied the amplitude of loading, by generating both low (0.4 MPa) and physiologic (5 MPa) HP levels. hASCs (10×106 cells/mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 4 weeks: (1) 0.4 MPa Pulsatile HP; (2) 5 MPa Pulsatile HP; and (3) Static. In the HNC study, the best tissue development was achieved by the pulsatile HP regimen, whereas in the hASC study, greater chondrogenic differentiation and matrix deposition were obtained for physiologic loading, as evidenced by gene expression of aggrecan, collagen type II, and sox-9; metachromatic staining of cartilage extracellular matrix; and immunolocalization of collagens. We thus propose that both HNCs and hASCs detect and respond to physical forces, thus resembling joint loading, by enhancing cartilage tissue development in a frequency- and

  9. Mem-ADSVM: A two-layer multi-label predictor for identifying multi-functional types of membrane proteins.

    PubMed

    Wan, Shibiao; Mak, Man-Wai; Kung, Sun-Yuan

    2016-06-07

    Identifying membrane proteins and their multi-functional types is an indispensable yet challenging topic in proteomics and bioinformatics. However, most of the existing membrane-protein predictors have the following problems: (1) they do not predict whether a given protein is a membrane protein or not; (2) they are limited to predicting membrane proteins with single-label functional types but ignore those with multi-functional types; and (3) there is still much room for improvement for their performance. To address these problems, this paper proposes a two-layer multi-label predictor, namely Mem-ADSVM, which can identify membrane proteins (Layer I) and their multi-functional types (Layer II). Specifically, given a query protein, its associated gene ontology (GO) information is retrieved by searching a compact GO-term database with its homologous accession number. Subsequently, the GO information is classified by a binary support vector machine (SVM) classifier to determine whether it is a membrane protein or not. If yes, it will be further classified by a multi-label multi-class SVM classifier equipped with an adaptive-decision (AD) scheme to determine to which functional type(s) it belongs. Experimental results show that Mem-ADSVM significantly outperforms state-of-the-art predictors in terms of identifying both membrane proteins and their multi-functional types. This paper also suggests that the two-layer prediction architecture is better than the one-layer for prediction performance. For reader׳s convenience, the Mem-ADSVM server is available online at http://bioinfo.eie.polyu.edu.hk/MemADSVMServer/. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Dynamic analysis of liquid-lubricated hydrostatic journal bearings

    SciTech Connect

    Kocur, J.A. Jr.

    1990-01-01

    A hybrid bearing reduces the dependency of its behavior on the lubricant viscosity, bearing clearance, bearing surface area by combining the hydrostatic and hydrodynamic effects. The combination permits the hybrid bearing to be incorporated into rotor designs, where the working fluids of the rotor may be used in place of externally supplied lubricants. An effective and practical method to predict the static and dynamic behavior of hybrid bearings is developed. The model includes the three major fluid effects in the bearing; the orifice restriction, inertia losses at the pocket edges, and hydrodynamic effects on the bearing land regions. Lubrication is modeled and calculated using a finite element solution of Reynolds equation with turbulence corrections.

  11. Ultrahigh hydrostatic pressure extraction of flavonoids from Epimedium koreanum Nakai

    NASA Astrophysics Data System (ADS)

    Hou, Lili; Zhang, Shouqin; Dou, Jianpeng; Zhu, Junjie; Liang, Qing

    2011-02-01

    Herba Epimedii is one of the most famous Chinese herbal medicines listed in the Pharmacopoeia of the People's Republic of China, as one of the representatives of traditional Chinese herb, it has been widely applied in the field of invigorate the kidney and strengthen 'Yang'. The attention to Epimedium extract has more and more increased in recent years. In this work, a novel extraction technique, ultra-high hydrostatic pressure extraction (UPE) technology was applied to extract the total flavonoids of E. koreanum. Three factors (pressure, ethanol concentration and extraction time) were chosen as the variables of extraction experiments, and the optimum UPE conditions were pressure 350 MPa; ethanol concentration 50% (v/v); extraction time 5 min. Compared with Supercritical CO2 extraction, Reflux extraction and Ultrasonic-assisted extraction, UPE has excellent advantages (shorter extraction time, higher yield, better antioxidant activity, lower energy consumption and eco-friendly).

  12. Damage Characterization in Copper Deformed under Hydrostatic Stress - Experimental Analysis

    SciTech Connect

    Flater, P. J.; House, J. W.; Nixon, M. E.

    2006-07-28

    The results of an experimental investigation designed to determine the effect of damage created by hydrostatic tensile loading on the properties of copper are reported. Three metallurgical conditions of half-hard OFHC copper were investigated; as worked; annealed 2hr at 400 deg. C ({approx}40 micron grain diameter); and annealed 2hr at 800 deg. C ({approx}80 micron grain diameter). Mechanical property characterization included uniaxial compression tests. High rate plasticity and damage was introduced by Taylor and rod-on-rod impact tests. The damage from the high rate experiments was characterized using optical and scanning electron microscopy. Quasi-static compression specimens machined from recovered high rate samples were tested to determine the influence of damage on the mechanical response of the material. The compression test results will be discussed in relationship to the starting microstructure and the extent of damaged introduced into the material.

  13. Hydrometer calibration by hydrostatic weighing with automated liquid surface positioning

    NASA Astrophysics Data System (ADS)

    Aguilera, Jesus; Wright, John D.; Bean, Vern E.

    2008-01-01

    We describe an automated apparatus for calibrating hydrometers by hydrostatic weighing (Cuckow's method) in tridecane, a liquid of known, stable density, and with a relatively low surface tension and contact angle against glass. The apparatus uses a laser light sheet and a laser power meter to position the tridecane surface at the hydrometer scale mark to be calibrated with an uncertainty of 0.08 mm. The calibration results have an expanded uncertainty (with a coverage factor of 2) of 100 parts in 106 or less of the liquid density. We validated the apparatus by comparisons using water, toluene, tridecane and trichloroethylene, and found agreement within 40 parts in 106 or less. The new calibration method is consistent with earlier, manual calibrations performed by NIST. When customers use calibrated hydrometers, they may encounter uncertainties of 370 parts in 106 or larger due to surface tension, contact angle and temperature effects.

  14. High hydrostatic pressure tolerance of four different anhydrobiotic animal species.

    PubMed

    Horikawa, Daiki D; Iwata, Ken-Ichi; Kawai, Kiyoshi; Koseki, Shigenobu; Okuda, Takashi; Yamamoto, Kazutaka

    2009-03-01

    High hydrostatic pressure (HHP) can induce physical changes in DNA, proteins, and lipids, causing lethal or sublethal damage to organisms. However, HHP tolerance of animals has not been studied sufficiently. In this study, HHP tolerance of four species of invertebrate anhydrobiotes (the tardigrade Milnesium tardigradum, a nematode species in the family Plectidae, larvae of Polypedilum vanderplanki, and cysts of Artemia franciscana), which have the potential to enter anhydrobiosis upon desiccation, were investigated by exposing them to 1.2 GPa for 20 minutes. This exposure killed the anhydrobiotes in their ordinary hydrated state, but did not affect their survival in the anhydrobiotic state. The results indicated that the hydrated anhydrobiotes were vulnerable to HHP, but that HHP of 1.2 GPa was not sufficient to kill them in anhyrdobiosis.

  15. Oscillatory high hydrostatic pressure inactivation of Zygosaccharomyces bailii.

    PubMed

    Palou, E; López-Malo, A; Barbosa-Cánovas, G V; Welti-Chanes, J; Swanson, B G

    1998-09-01

    Zygosaccharomyces bailii inactivation was evaluated in oscillatory high hydrostatic pressure (HHP) treatments at sublethal pressures (207, 241, or 276 MPa) and compared with continuous HHP treatments in laboratory model systems with a water activity (aw) of 0.98 and pH 3.5. The yeast was inoculated into laboratory model systems and subjected to HHP in sterile bags. Two HHP treatments were conducted: continuous (holding times of 5, 10, 15, 20, 30, 60, or 90 min) and oscillatory (two, three, or four cycles with holding times of 5 min and two cycles with holding times of 10 min). Oscillatory pressure treatments increased the effectiveness of HHP processing. For equal holding times, Z. bailii counts decreased as the number of cycles increased. Holding times of 20 min in HHP oscillatory treatments at 276 MPa assured inactivation (< 10 CFU/ml) of Z. bailii initial inoculum. Oscillatory pressurization could be useful to decrease Z. bailii inactivation time.

  16. Hydrostatic factors affect the gravity responses of algae and roots

    NASA Technical Reports Server (NTRS)

    Staves, Mark P.; Wayne, Randy; Leopold, A. C.

    1991-01-01

    The hypothesis of Wayne et al. (1990) that plant cells perceive gravity by sensing a pressure differential between the top and the bottom of the cell was tested by subjecting rice roots and cells of Caracean algae to external solutions of various densities. It was found that increasing the density of the external medium had a profound effect on the polar ratio (PR, the ratio between velocities of the downwardly and upwardly streaming cytoplasm) of the Caracean algae cells. When these cells were placed in solutions of denser compound, the PR decreased to less than 1, as the density of the external medium became higher than that of the cell; thus, the normal gravity-induced polarity was reversed, indicating that the osmotic pressure of the medium affects the cell's ability to respond to gravity. In rice roots, an increase of the density of the solution inhibited the rate of gravitropism. These results agree with predictions of a hydrostatic model for graviperception.

  17. Hydrostatic equilibrium and stellar structure in f(R) gravity

    SciTech Connect

    Capozziello, S.; De Laurentis, M.; Odintsov, S. D.; Stabile, A.

    2011-03-15

    We investigate the hydrostatic equilibrium of stellar structure by taking into account the modified Lane-Emden equation coming out from f(R) gravity. Such an equation is obtained in a metric approach by considering the Newtonian limit of f(R) gravity, which gives rise to a modified Poisson equation, and then introducing a relation between pressure and density with polytropic index n. The modified equation results an integro-differential equation, which, in the limit f(R){yields}R, becomes the standard Lane-Emden equation. We find the radial profiles of the gravitational potential by solving for some values of n. The comparison of solutions with those coming from general relativity shows that they are compatible and physically relevant.

  18. Multi-Pulsed High Hydrostatic Pressure Treatment of Foods.

    PubMed

    Buzrul, Sencer

    2015-05-25

    Multi-pulsed high hydrostatic pressure (mpHHP) treatment of foods has been investigated for more than two decades. It was reported that the mpHHP treatment, with few exceptions, is more effective than the classical or single-pulsed HHP (spHHP) treatment for inactivation of microorganisms in fruit juice, dairy products, liquid whole egg, meat products, and sea foods. Moreover, the mpHHP treatment could be also used to inactivate enzymes in foods and to increase the shelf-life of foods. The effects of the mpHHP treatment of foods are summarized and the differences between the mpHHP and spHHP are also emphasized.

  19. On the Resistance of Nanofibrous Superhydrophobic Coatings to Hydrostatic Pressures

    NASA Astrophysics Data System (ADS)

    Bucher, T. M.; Emami, B.; Vahedi Tafreshi, H.; Gad-El-Hak, M.; Tepper, G. C.

    2011-11-01

    We present a numerical study aimed at investigating the influence of microstructural parameters on the resistance of submerged fibrous superhydrophobic coatings to elevated hydrostatic pressures. In particular, we generate 3-D virtual geometries comprised of randomly or orthogonally oriented horizontal fibers with bimodal diameter distributions resembling the microstructure of coatings produced via DC and AC electrospinning, respectively. These virtual geometries are then used as the computational domain for performing Full Morphology (FM) simulations to establish a relationship between the coatings' critical pressure--pressure beyond which the surface departs from the Cassie state--and their microstructures. Our numerical simulations are aimed at providing guidelines for the design and optimization of the coatings' microstructures. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.

  20. A finite element simulation scheme for biological muscular hydrostats.

    PubMed

    Liang, Y; McMeeking, R M; Evans, A G

    2006-09-07

    An explicit finite element scheme is developed for biological muscular hydrostats such as squid tentacles, octopus arms and elephant trunks. The scheme is implemented by embedding muscle fibers in finite elements. In any given element, the fiber orientation can be assigned arbitrarily and multiple muscle directions can be simulated. The mechanical stress in each muscle fiber is the sum of active and passive parts. The active stress is taken to be a function of activation state, muscle fiber shortening velocity and fiber strain; while the passive stress depends only on the strain. This scheme is tested by simulating extension of a squid tentacle during prey capture; our numerical predictions are in close correspondence with existing experimental results. It is shown that the present finite element scheme can successfully simulate more complex behaviors such as torsion of a squid tentacle and the bending behavior of octopus arms or elephant trunks.

  1. Silicide/silicon Schottky barriers under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Werner, Jürgen H.

    1989-04-01

    We investigate several silicide/silicon Schottky barrier heights under hydrostatic pressures up to 10 kbar. The barriers of polycrystalline TiSi2, PtSi, and WTi on n-type Si decrease with -1.l3, -1.35, and -1.42 meV/kbar, respectively. The coefficients for A- and B-type NiSi2/Si amount to -0.77 and -0.89 meV/kbar and are too small to support models which ascribe the l40 meV barrier difference of these two types to different interface bond lengths. The pressure coefficients are, on the other hand, within a range of predictions of Cardona and Christensen which are based on pure bulk properties.

  2. Multi-Pulsed High Hydrostatic Pressure Treatment of Foods

    PubMed Central

    Buzrul, Sencer

    2015-01-01

    Multi-pulsed high hydrostatic pressure (mpHHP) treatment of foods has been investigated for more than two decades. It was reported that the mpHHP treatment, with few exceptions, is more effective than the classical or single-pulsed HHP (spHHP) treatment for inactivation of microorganisms in fruit juice, dairy products, liquid whole egg, meat products, and sea foods. Moreover, the mpHHP treatment could be also used to inactivate enzymes in foods and to increase the shelf-life of foods. The effects of the mpHHP treatment of foods are summarized and the differences between the mpHHP and spHHP are also emphasized. PMID:28231197

  3. Investigating the nucleation of protein crystals with hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Kadri, A.; Damak, M.; Jenner, G.; Lorber, B.; Giegé, R.

    2003-12-01

    Hydrostatic pressure in the 0.1-75 MPa range has been used as a non-invasive tool to study the crystallization process of the tetragonal crystal form of the protein thaumatin (Mr 22 200). Crystals were prepared within agarose gel and at temperatures in the range from 283 to 303 K. The solubility, i.e. the concentration of soluble macromolecules remaining in equilibrium with the crystals, decreases when the pressure increases and when the temperature decreases. High pressure was used to probe the nucleation behaviour of thaumatin. The pressure dependence of the nucleation rate leads to an activation volume of -46.5 cm3 mol-1. It is shown that an increase in pressure decreases the enthalpy, the entropy and the free energy of crystallization of thaumatin. The data are discussed in the light of the results of crystallographic analyses and of the structure of the protein.

  4. Porcine radial artery decellularization by high hydrostatic pressure.

    PubMed

    Negishi, Jun; Funamoto, Seiichi; Kimura, Tsuyoshi; Nam, Kwangoo; Higami, Tetsuya; Kishida, Akio

    2015-11-01

    Many types of decellularized tissues have been studied and some have been commercially used in clinics. In this study, small-diameter vascular grafts were made using HHP to decellularize porcine radial arteries. One decellularization method, high hydrostatic pressure (HHP), has been used to prepare the decellularized porcine tissues. Low-temperature treatment was effective in preserving collagen and collagen structures in decellularized porcine carotid arteries. The collagen and elastin structures and mechanical properties of HHP-decellularized radial arteries were similar to those of untreated radial arteries. Xenogeneic transplantation (into rats) was performed using HHP-decellularized radial arteries and an untreated porcine radial artery. Two weeks after transplantation into rat carotid arteries, the HHP-decellularized radial arteries were patent and without thrombosis. In addition, the luminal surface of each decellularized artery was covered by recipient endothelial cells and the arterial medium was fully infiltrated with recipient cells.

  5. Cell Membranes Under Hydrostatic Pressure Subjected to Micro-Injection

    NASA Astrophysics Data System (ADS)

    Vassilev, Vassil M.; Kostadinov, Kostadin G.; Mladenov, Ivaïlo M.; Shulev, Assen A.; Stoilov, Georgi I.; Djondjorov, Peter A.

    2011-04-01

    The work is concerned with the determination of the mechanical behaviour of cell membranes under uniform hydrostatic pressure subject to micro-injections. For that purpose, assuming that the shape of the deformed cell membrane is axisymmetric a variational statement of the problem is developed on the ground of the so-called spontaneous curvature model. In this setting, the cell membrane is regarded as an axisymmetric surface in the three-dimensional Euclidean space providing a stationary value of the shape energy functional under the constraint of fixed total area and fixed enclosed volume. The corresponding Euler-Lagrange equations and natural boundary conditions are derived, analyzed and used to express the forces and moments in the membrane. Several examples of such surfaces representing possible shapes of cell membranes under pressure subjected to micro injection are determined numerically.

  6. Two-Phase Solid/Fluid Simulation of Dense Granular Flows With Dilatancy Effects

    NASA Astrophysics Data System (ADS)

    Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Narbona-Reina, Gladys; Kone, El Hadj

    2017-04-01

    Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [1]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/ dilatation of the granular media and its interaction with the pore fluid pressure [2]. The model is derived from a 3D two-phase model proposed by Jackson [3] and the mixture equations are closed by a weak compressibility relation. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To account for this transfer of fluid into and out of the mixture, a two-layer model is proposed with a fluid or a solid layer on top of the two-phase mixture layer. Mass and momentum conservation are satisfied for the two phases, and mass and momentum are transferred between the two layers. A thin-layer approximation is used to derive average equations. Special attention is paid to the drag friction terms that are responsible for the transfer of momentum between the two phases and for the appearance of an excess pore pressure with respect to the hydrostatic pressure. Interestingly, when removing the role of water, our model reduces to a dry granular flow model including dilatancy. We first compare experimental and numerical results of dilatant dry granular flows. Then, by quantitatively comparing the results of simulation and laboratory experiments on submerged granular flows, we show that our model

  7. Thermal conductivity and compressive strain of foam neoprene insulation under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Bardy, Erik; Mollendorf, Joseph; Pendergast, David

    2005-10-01

    The purpose of this study was to show that the thermal properties of foam neoprene under hydrostatic pressure cannot be predicted by theoretical means, and that uni-axial pressure cannot simulate hydrostatic compression. The thermal conductivity and compressive strain of foam neoprene were measured under hydrostatic pressure. In parallel, uni-axial compressive strain data were collected. The experimental set-up and data were put into perspective with past published studies. It was shown that uni-axial compression yielded strains 20-25% greater than did hydrostatic compression. This suggests the need for direct hydrostatic pressure measurement. For comparison to hydrostatic experimental data, a series of thermal conductivity theories of two phase composites based on particulate phase geometry were utilized. Due to their dependence on the porosity and constituent thermal conductivities, a model to predict porosity under hydrostatic pressure was used and an empirical correlation was derived to calculate the thermal conductivity of pure neoprene rubber from experimental data. It was shown that, although some agreement between experimental data and thermal conductivity theories was present, no particular theory can be used because they all fail to model the complex structure of the pores. It was therefore concluded that an experimental programme, such as reported here, is necessary for direct measurement.

  8. Numerical theory of rotation of the deformable Earth with the two-layer fluid core. Part 1: Mathematical model

    NASA Astrophysics Data System (ADS)

    Krasinsky, G. A.

    2006-11-01

    Improved differential equations of the rotation of the deformable Earth with the two-layer fluid core are developed. The equations describe both the precession-nutational motion and the axial rotation (i.e. variations of the Universal Time UT). Poincaré’s method of modeling the dynamical effects of the fluid core, and Sasao’s approach for calculating the tidal interaction between the core and mantle in terms of the dynamical Love number are generalized for the case of the two-layer fluid core. Some important perturbations ignored in the currently adopted theory of the Earth’s rotation are considered. In particular, these are the perturbing torques induced by redistribution of the density within the Earth due to the tidal deformations of the Earth and its core (including the effects of the dissipative cross interaction of the lunar tides with the Sun and the solar tides with the Moon). Perturbations of this kind could not be accounted for in the adopted Nutation IAU 2000, in which the tidal variations of the moments of inertia of the mantle and core are the only body tide effects taken into consideration. The equations explicitly depend on the three tidal phase lags δ, δ c, δ i responsible for dissipation of energy in the Earth as a whole, and in its external and inner cores, respectively. Apart from the tidal effects, the differential equations account for the non-tidal interaction between the mantle and external core near their boundary. The equations are presented in a simple close form suitable for numerical integration. Such integration has been carried out with subsequent fitting the constructed numerical theory to the VLBI-based Celestial Pole positions and variations of UT for the time span 1984 2005. Details of the fitting are given in the second part of this work presented as a separate paper (Krasinsky and Vasilyev 2006) hereafter referred to as Paper 2. The resulting Weighted Root Mean Square (WRMS) errors of the residuals d θ, sin θd φ for

  9. Diaphragm-based fiber optic Fabry-Perot hydrophone with hydrostatic pressure compensation

    NASA Astrophysics Data System (ADS)

    Wang, Zhaogang; Zhang, Wentao; Li, Fang

    2013-09-01

    A fiber optic Fabry-Perot (FP) hydrophone with hydrostatic pressure compensation was demonstrated. A polyimide (PI) diaphragm attached on the end of an Acrylonitrile Butadiene Styrene (ABS) tube was used as the sensing element. A pair of grooves was designed in an inner ABS tube to connect the Fabry-Perot cavity with the outside environment, which made the hydrophone hydrostatic pressure compensated. The operation principle, design and testing of polyimide diaphragm-based sensor were described. Experiment results show that it has not only high stability in different hydrostatic pressures, but also flat frequency response of about 158 ±3 dB within 300-3000 Hz.

  10. Microstructure evolution in age-hardenable aluminium alloy during processing by hydrostatic extrusion.

    PubMed

    Lewandowska, M

    2006-10-01

    In the present work, scanning and transmission electron microscopy were used to investigate the microstructural evolution occurring during the hydrostatic extrusion of an age-hardenable aluminium alloy. It was shown that processing by hydrostatic extrusion leads to grain refinement to 95 nm in equivalent diameter. Hydrostatic extrusion also influences the geometrical parameters of two different types of particle: intermetallic inclusions and precipitates. The intermetallic inclusions slightly decrease in mean equivalent diameter, but their size remains at the micrometre level. The precipitates are fragmented to nanoscale spherical particles, and their evolution delays the process of grain refinement.

  11. Using stable water isotopes in a two-layer soil moisture conceptual framework to understand transpiration dynamics in a semiarid shrubland

    NASA Astrophysics Data System (ADS)

    Szutu, D. J.; Papuga, S. A.; Wehr, R.

    2014-12-01

    Semiarid shrublands and other dryland ecosystems are highly sensitive to precipitation pulses. Because the frequency and magnitude of precipitation events have been projected to change for these ecosystems, the nature of these pulses and how they are distributed as moisture in the soil profile are also expected to change. Previous research has suggested that transpiration dynamics in drylands are associated with deep soil moisture, which accumulates after large rainfall events. Because transpiration is the productive component of evapotranspiration in that it is water used toward biomass accumulation, a hypothetical decrease in large rainfall events would have major consequences for the health and functioning of dryland ecosystems. Furthermore, as drylands account for nearly 40% of terrestrial biomes, these cascading changes have the potential to impact global water and carbon budgets. Still, in pulse-dependent dryland ecosystems, the relative contribution of transpiration to evapotranspiration and the temporal dynamics of this contribution are not well understood. The objective of this research is to better characterize the temporal dynamics of transpiration in dryland ecosystems. We present the relative contribution of transpiration to evapotranspiration over the course of a year from eddy covariance and sap flow measurements taken at a creosotebush-dominated shrubland ecosystem in southern Arizona. We analyze soil moisture and stable water isotopes within the context of a two-layer soil moisture conceptual framework in an attempt to identify the source water for transpiration. We use these results to explain the temporal dynamics of transpiration in this semiarid shrubland. Finally, we put our results in the context of regional climate projections to suggest how this dryland ecosystem might be impacted in the future. We expect our study will contribute to understanding where precipitation pulses are distributed in the soil moisture profile and when these pulses

  12. Comparative simulations of a two-layer landfill barrier using the HELP Version 2. 0 and UNSAT-H Version 2. 0 computer codes

    SciTech Connect

    Nichols, W.E.

    1991-01-01

    This report documents the results of a simulation of the performance of a two-layer infiltration barrier for a nonradioactive dangerous waste landfill (NRDWL) at the US Department of Energy's Hanford Site in semi-arid southeast Washington State. The performance of the barrier was simulated for a period of 10 years using the UNSAT-H version 2.0 groundwater flow computer code. Pacific Northwest Laboratory performed this simulation to compare results using UNSAT-H 2.0 with those of the US Environmental Protection Agency's Hydrologic Evaluation of Landfill Performance (HELP) version 2.0 code. A conceptualization of the actual landfill barrier design was modeled using both codes. This model was simulated using 10 years of daily meteorological data collected at the Hanford Meteorological Station from 1979 through 1988. The intent of the comparison was to demonstrate that HELP conservatively predicts deep percolation of meteoric water at the Hanford Site. This demonstration required that the two codes be used to simulate the same conceptual model using identical, or at least essentially equivalent, input data. Comparing the results of the 10-year simulations showed that for the meteorological data and soil properties modeled the HELP 2.0 code was more conservative than the UNSAT-H code. HELP predicted a net drainage or deep percolation of 0.3592 cm (0.1556 in.) from the barrier for the 10-year period simulated. None to the UNSAT-H simulations predicted any deep percolation. HELP also predicted a greater proportion of precipitation returned to the atmosphere through evapotranspiration than did the UNSAT-H simulations in spite of the larger precipitation values being provided to HELP through an apparent data entry error. 14 refs., 11 figs., 8 tabs.

  13. Hydrostatic pressure effect on the transport properties in TiO superconducting thin films

    NASA Astrophysics Data System (ADS)

    Liu, X.; Zhang, C.; Hao, F. X.; Wang, T. Y.; Fan, Y. J.; Yin, Y. W.; Li, X. G.

    2017-09-01

    The superconducting properties of the TiO epitaxial thin films were systematically investigated under hydrostatic pressures (P ) up to 2.13 GPa. At ambient pressure, the normal state resistivity increases with decreasing temperature, and steeply increases below Tkink˜ 115 K . With further reducing temperature to Tc˜ 5.99 K , the thin film enters into a superconducting state. Interestingly, the superconducting temperature Tc gradually decreases upon increasing P , and the decreasing rate of Tc with P is much larger than the McMillan theoretical expectation. In contrast, Tkink increases with P and a remarkable resistivity enhancement was observed in the temperature range between Tkink and Tc. The variations of Tc,Tkink , and normal state resistivity under high pressure may be induced by the charge localization related to the atomic vacancies rearrangement in TiO thin film. Furthermore, the temperature dependencies of the upper critical field Hc 2(T ) indicate that both the orbital and Pauli-paramagnetic pair-breaking effects should be taken into account. Finally, the thermally activated flux flow investigations under different pressures suggest that the pressure will suppress the thermal activate energy.

  14. Effects of high hydrostatic pressure on secondary structure and emulsifying behavior of sweet potato protein

    NASA Astrophysics Data System (ADS)

    Mehmood Khan, Nasir; Mu, Tai-Hua; Sun, Hong-Nan; Zhang, Miao; Chen, Jing-Wang

    2015-04-01

    In this study, secondary structures of sweet potato protein (SPP) after high hydrostatic pressure (HHP) treatment (200-600 MPa) were evaluated and emulsifying properties of emulsions with HHP-treated SPP solutions in different pH values (3, 6, and 9) were investigated. Circular dichroism analysis confirmed the modification of the SPP secondary structure. Surface hydrophobicity increased at pH 3 and decreased at 6 and 9. Emulsifying activity index at pH 6 increased with an increase in pressure, whereas emulsifying stability index increased at pH 6 and 9. Oil droplet sizes decreased, while volume frequency distribution of the smaller droplets increased at pH 3 and 6 with the HHP treatment. Emulsion viscosity increased at pH 6 and 9 and pseudo-plastic flow behaviors were not altered for all emulsions produced with HHP-treated SPP. These results suggested that HHP could modify the SPP structure for better emulsifying properties, which could increase the use of SPP emulsion in the food industry.

  15. Spin torque driven dynamics of a coupled two-layer structure: Interplay between conservative and dissipative coupling

    NASA Astrophysics Data System (ADS)

    Romera, M.; Lacoste, B.; Ebels, U.; Buda-Prejbeanu, L. D.

    2016-09-01

    The general concepts of spin wave theory are adapted to the spin torque driven dynamics of a self-polarized system based on two layers coupled via interlayer exchange (conservative coupling) and mutual spin torque (dissipative coupling). An analytical description of the nonlinear dynamics is proposed and validated through numerical simulations. In contrast to the single layer model, the phase equation of the coupled system has a contribution coming from the dissipative part of the LLGS equation. It is shown that this is a major contribution to the frequency mandatory to describe well the most basic features of the dynamics of this coupled system. Using the proposed model a specific feature of coupled dynamics is addressed: the redshift to blueshift transition observed in the frequency current dependence of this kind of exchange coupled systems upon increasing the applied field. It is found that the blueshift regime can only occur in a region of field where the two linear eigenmodes contribute equally to the steady state mode (i.e., high mode hybridization). Finally, a general perturbed Hamiltonian equation for the coupled system is proposed.

  16. Crystallochemistry of the novel two-layer RECuMg{sub 4} (RE=La, Tb) ternary compounds

    SciTech Connect

    Solokha, P. De Negri, S.; Pavlyuk, V.; Marciniak, B.

    2007-11-15

    The crystal structures of the new ternary compounds LaCuMg{sub 4} and TbCuMg{sub 4} were studied by X-ray powder diffraction and single-crystal methods, respectively. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS) was used for examining microstructure and phase composition. LaCuMg{sub 4} crystallizes in the UCoAl{sub 4} structure type (space group P6-bar 2m, Pearson code hP18, a=1.03911(1), c=0.45126(1) nm, Z=3, R{sub F}=0.0654), while TbCuMg{sub 4} exhibits a new structure (space group Cmmm, Pearson code oS48, a=1.35797(6), b=2.03333(9), c=0.39149(2) nm, Z=8, wR{sub 2}=0.0426). Both structures represent a family of two-layer compounds. All interatomic distances indicate metallic type bonding. The structural peculiarities of these compounds and their relations are discussed. - Graphical abstract: Slightly distorted body centered Mg blocks as structural motifs in the LaCuMg{sub 4} and TbCuMg{sub 4} compounds.

  17. A novel technique for chest drain removal using a two layer method with triclosan-coated sutures

    PubMed Central

    Yokoyama, Yujiro; Nakagomi, Takahiro; Shikata, Daichi

    2017-01-01

    In thoracic surgery, a thoracic drain is always inserted after the surgical procedure. Repair of the wound after removal of the thoracic tube is performed postoperatively, but no universally standard methods currently exists for this tube removal. Here we report a technique using triclosan-coated sutures that is used in thoracic surgery in our hospital. There are several advantages of this technique. First, there is no need for stitches removal on follow-up. Second, it prevents the leakage of pleural exudate because of the tight two-layer sutures. In addition, it was observed to be superior in terms of both wound healing and cosmetic aspects, due to the layer-to-layer sutures. The use of triclosan-coated sutures helps prevent infection and empyema is quite unlikely to occur as the result of the tight ligating of the muscular layer using these sutures. We applied this method in 168 patients over a period of 24 months. There were no complications on removal of the chest tube such as infection, fluid leakage or opening of the surgical wound. PMID:28203426

  18. A two-layer soil moisture conceptual framework for exploring land surface-atmosphere interactions in water-limited ecosystem

    NASA Astrophysics Data System (ADS)

    Papuga, S. A.

    2014-12-01

    The exchange of water, energy, and carbon between the land surface and the atmosphere is largely influenced by vegetation. In turn, vegetation is strongly influenced by the partitioning of precipitation into evapotranspiration, soil moisture, and runoff. Ultimately, the hydrologic cycle exerts a strong control on the climate system. In fact, positive feedbacks between vegetation and the hydrologic cycle at small scales may have the ability to elicit non-linear responses with important large scale consequences. Therefore, capturing the synergies between hydrologic processes at different space and time scales is necessary for appropriately modeling the influence of vegetation and the hydrologic cycle on the climate system. Understanding the controls on land-atmosphere interactions and how they influence larger scale feedbacks will become increasingly important as climatic and other global changes continue to alter the water availability of our ecosystems. Water-limited ecosystems are especially sensitive to precipitation changes, and therefore insights concerning how their functioning responds to possible changes in precipitation patterns are important in understanding future climate scenarios. Over a decade of field work from my research group has highlighted the importance of deep soil moisture (from large storms) in the healthy functioning of water-limited ecosystems. This has led to the development of a two-layer soil moisture conceptual framework for exploring land surface-atmosphere interactions in water-limited ecosystems. Here I demonstrate how this framework can been used to link small scale processes investigated in field with large scale processes for water-limited ecosystems.

  19. An analytical model for solute transport through a GCL-based two-layered liner considering biodegradation.

    PubMed

    Guan, C; Xie, H J; Wang, Y Z; Chen, Y M; Jiang, Y S; Tang, X W

    2014-01-01

    An analytical model for solute advection and dispersion in a two-layered liner consisting of a geosynthetic clay liner (GCL) and a soil liner (SL) considering the effect of biodegradation was proposed. The analytical solution was derived by Laplace transformation and was validated over a range of parameters using the finite-layer method based software Pollute v7.0. Results show that if the half-life of the solute in GCL is larger than 1 year, the degradation in GCL can be neglected for solute transport in GCL/SL. When the half-life of GCL is less than 1 year, neglecting the effect of degradation in GCL on solute migration will result in a large difference of relative base concentration of GCL/SL (e.g., 32% for the case with half-life of 0.01 year). The 100-year solute base concentration can be reduced by a factor of 2.2 when the hydraulic conductivity of the SL was reduced by an order of magnitude. The 100-year base concentration was reduced by a factor of 155 when the half life of the contaminant in the SL was reduced by an order of magnitude. The effect of degradation is more important in approving the groundwater protection level than the hydraulic conductivity. The analytical solution can be used for experimental data fitting, verification of complicated numerical models and preliminary design of landfill liner systems.

  20. A two-layer Conditional Random Field model for simultaneous classification of land cover and land use

    NASA Astrophysics Data System (ADS)

    Albert, L.; Rottensteiner, F.; Heipke, C.

    2014-08-01

    This paper proposes a two-layer Conditional Random Field model for simultaneous classification of land cover and land use. Both classification tasks are integrated into a unified graphical model, which is reasonable due to the fact that land cover and land use exhibit strong contextual dependencies. In the CRF, we distinguish a land cover layer and a land use layer. Both layers differ with respect to the entities corresponding to the nodes and the classes to be distinguished. In the land cover layer, the nodes correspond to superpixels extracted from the image data, whereas in the land use layer the nodes correspond to objects of a geospatial land use database. Statistical dependencies between land cover and land use are explicitly modelled as pair-wise potentials. Thus, we obtain a consistent model, where the relations between land cover and land use are learned from representative training data. The approach is designed for input data based on aerial images. Experiments are performed on an urban test site. The experiments show the feasibility of the combination of both classification tasks into one overall approach and investigate the influence of the size of the superpixels on the classification result.