Science.gov

Sample records for aligned breakup deformation

  1. Deformed halo nuclei probed by breakup reactions

    NASA Astrophysics Data System (ADS)

    Nakamura, Takashi

    2013-07-01

    Breakup reactions play important roles in elucidating the structures near the drip lines, such as nuclear halo. The recent experimental results using the Coulomb and nuclear breakup reactions for the neutron-drip-line nuclei at the new-generation RI beam facility, RIBF at RIKEN, are presented. Focuses are put on the results on the newly found halo nucleus 31Ne, which is intriguing also in that this nucleus is in the island-of-inversion and thus could be strongly deformed. The results on other Ne/Mg/Si neutron rich isotopes ranging from N=20 towards N=28 are also briefly reported. The first breakup experiments using SAMURAI facility at RIBF and future perspectives are also presented.

  2. Droplet Deformation Prediction With the Droplet Deformation and Breakup Model (DDB)

    NASA Technical Reports Server (NTRS)

    Vargas, Mario

    2012-01-01

    The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.

  3. The effect of surfactants on drop deformation, collisions and breakup

    NASA Astrophysics Data System (ADS)

    Cristini, Vittorio; Zhou, Hua; Lowengrub, John; Macosko, Chris

    2001-11-01

    The dynamics of deformable drops in viscous flows are investigated via numerical simulations. A novel finite-element/sharp-interface algorithm based on adaptive tetrahedra (Hooper et al. 2001) for simulations is used. Three-dimensional drop deformation is studied in the presence of a surfactant coating of the drop interface. Under these conditions, flow-driven surfactant redistribution induces Marangoni stresses at the interface that modify the hydrodynamics and thus affect the rheology of emulsions and polymer blends. The effects of the equation of state that relates the concentration of surfactant on the interface to the surface tension, and of diffusion and solubility of surfactant molecules are included in our model. Results of simulations under strong-flow conditions are presented that describe the effect of surfactants on the development of lamellar microstructures in emulsions (Wetzel and Tucker 2001; Cristini et al. 2001). More stable drop lamellae with larger interfacial area are predicted in the presence of surfactants, in agreement with recent experimental observations (Jeon and Macosko 2000). In addition, the feasibility of accurate simulations of drop collisions and breakup is demonstrated using our model, and preliminary results on the effects of surfactants on these phenomena are presented.

  4. Investigation on Transient Oscillation of Droplet Deformation before Conical Breakup under Alternating Current Electric Field.

    PubMed

    Yan, Haipeng; He, Limin; Luo, Xiaoming; Wang, Jing; Huang, Xin; Lü, Yuling; Yang, Donghai

    2015-08-04

    In this paper, the conical breakup of a water droplet suspended in oil under the alternating current (ac) electric field was experimentally studied with the help of a high-speed video camera. We observed three stages of transient oscillation of deformation characterized by deformation degree l* before the conical breakup that were described in detail. Then a theoretical model was developed to find out the dynamic mechanisms of that behavior. Despite a very small discrepancy, good agreement between model predictions and experimental observations of the evolution of the droplet deformation was observed, and the possible reasons for the discrepancy were discussed as well. Finally, the stresses on the interface were calculated with the theoretical model and their influence on the dynamic behavior before the breakup was obtained. The differences between the droplet breakup mode of ac and direct current electric field are also discussed in our paper.

  5. Deformation and breakup of round drops and nonturbulent liquid jets in uniform crossflows

    NASA Astrophysics Data System (ADS)

    Aalburg, Christian

    2002-09-01

    The deformation and breakup properties of liquid drops and round liquid jets in uniform crossflows were studied computationally, motivated by applications to the behavior of sprays in crossflows found in a variety of power and propulsion systems. The objective of the present investigation was to extend the parameter range of past deformation and breakup studies, by means of numerical computations, to conditions more representative of practical high-pressure spray combustion processes. The time-dependent, incompressible and two-dimensional Navier-Stokes equations were solved on a uniform, staggered grid using the projection method of Chorin (1968) and the Level Set method of Sussman et al. (1994). Numerical simulations of the effect of crossflows on the deformation and breakup of drops and round liquid jets were carried out for the following range of parameters to study the independent effects of four dimensionless variables that fully describe the problem: Weber numbers of 0.1--2,000,000, Ohnesorge numbers of 0.001--100, Reynolds numbers of 12.5--200 and liquid/gas density ratios of 2--infinity (the last by Richardson extrapolation). The present results were in good agreement with existing measurements of deformation and breakup properties of both liquid drops and round liquid jets at large liquid/gas density ratios and with wake and drag properties of spheres and cylinders in crossflows. Similar to past experimental observations, remarkable similarities were observed between the breakup properties of round liquid jets and liquid drops. The liquid/gas density ratio was found to have a relatively small effect on deformation and breakup. Effects of Reynolds number variations were also small for conditions where the drag coefficient is relatively independent of the Reynolds number. As the Stokes flow regime is approached, however, the Weber number (We) required for breakup increases significantly due to increased drag coefficients. At large Ohnesorge number (Oh

  6. Constraining Lithosphere Deformation Modes during Continental Breakup for the Iberia-Newfoundland Conjugate Margins

    NASA Astrophysics Data System (ADS)

    Jeanniot, L.; Kusznir, N. J.; Mohn, G.; Manatschal, G.

    2014-12-01

    How the lithosphere and asthenosphere deforms during continental rifting leading to breakup and sea-floor spreading initiation is poorly understood. Observations at present-day and fossil analogue rifted margins show a complex OCT architecture which cannot be explained by a single simplistic lithosphere deformation modes. This OCT complexity includes hyper-extended continental crust and lithosphere, detachments faults, exhumed mantle, continental slivers and scattered embryonic oceanic crust. We use a coupled kinematic-dynamic model of lithosphere and asthenosphere deformation to determine the sequence of lithosphere deformation modes leading to continental breakup for Iberia-Newfoundland conjugate margin profiles. We quantitatively calibrate the models using observed present-day water loaded subsidence and crustal thickness, together with subsidence history and the age of melt generation. Flow fields, representing a sequence of lithosphere deformation modes, are generated by a 2D finite element viscous flow model (FE-Margin), and used to advect lithosphere and asthenosphere temperature and material. FE-Margin is kinematically driven by divergent deformation in the upper 15-20 km of the lithosphere inducing passive upwelling below. Buoyancy enhanced upwelling (Braun et al. 2000) is also kinematically included. Melt generation by decompressional melting is predicted using the methodology of Katz et al., 2003. The extension magnitudes used in the lithosphere deformation models are taken from Sutra et al (2013). The best fit calibrated models of lithosphere deformation evolution for the Iberia-Newfoundland conjugate margins require (i) an initial broad region of lithosphere deformation and passive upwelling, (ii) lateral migration of deformation, (iii) an increase in extension rate with time, (iv) focussing of deformation and (v) buoyancy induced upwelling. The preferred calibrated models predict faster extension rates and earlier continental crustal rupture and

  7. Influences of periodic mechanical deformation on spiral breakup in excitable media.

    PubMed

    Chen, Jiang-Xing; Xu, Jiang-Rong; Yuan, Xiao-Ping; Ying, He-Ping

    2009-01-22

    Influences of periodic mechanical deformation (PMD) on spiral breakup that results from Doppler instability in excitable media are investigated. We present a new effect: a high degree of homogeneous PMD is favored to prevent the low-excitability-induced breakup of spiral waves. The frequency and amplitude of PMD are also significant for achieving this purpose. The underlying mechanism of successful control is also discussed, which is believed to be related to the increase of the minimum temporal period of the meandering spiral when the suitable PMD is applied.

  8. Deformation and breakup of a liquid droplet past a solid circular cylinder: a lattice Boltzmann study.

    PubMed

    Li, Qiuxiang; Chai, Zhenhua; Shi, Baochang; Liang, Hong

    2014-10-01

    In this paper, we present a numerical study on the deformation and breakup behavior of liquid droplet past a solid circular cylinder by using an improved interparticle-potential lattice Boltzmann method. The effects of the eccentric ratio β, viscosity ratio λ between the droplet and the surrounding fluid, surface wettability, and Bond number (Bo) on the dynamic behavior of the liquid droplet are considered. The parameter β represents the degree that the solid cylinder deviates from the center line, and Bo is the ratio between the inertial force and capillary force. Numerical results show that there are two typical patterns, i.e., breakup and no breakup, which are greatly influenced by the aforementioned parameters. When β increases to a critical value βc, the droplet can pass the circular cylinder without a breakup, otherwise, the breakup phenomenon occurs. The critical eccentric ratio βc increases significantly with increasing Bo for case with λ>1, while for the case with λ<1, the viscosity effects on the βc is not obvious when Bo is large. For the breakup case, the amount of deposited liquid on the tip of the circular cylinder is almost unaffected by β. In addition, the results also show that the viscosity ratio and wettability affect the deformation and breakup process of the droplet. For case with λ<1, the viscosity ratio plays a minor role in the thickness variations of the deposited liquid, which decreases to a nonzero constant eventually; while for λ>1, the increase of the viscosity ratio significantly accelerates the decrease of the deposited liquid, and finally no fluid deposits on the cylinder. In term of the wettability, there occurs continuous gas phase trapped by the wetting droplet, but this does not happen for nonwetting droplet. Besides, for λ<1, the time required to pass the cylinder (tp) decreases monotonically with decreasing contact angle, while a nonmonotonic decrease appears for λ>1. It is also found that tp decreases

  9. Deformation pathways and breakup modes in acoustically levitated bicomponent droplets under external heating

    NASA Astrophysics Data System (ADS)

    Pathak, Binita; Basu, Saptarshi

    2016-03-01

    Controlled breakup of droplets using heat or acoustics is pivotal in applications such as pharmaceutics, nanoparticle production, and combustion. In the current work we have identified distinct thermal acoustics-induced deformation regimes (ligaments and bubbles) and breakup dynamics in externally heated acoustically levitated bicomponent (benzene-dodecane) droplets with a wide variation in volatility of the two components (benzene is significantly more volatile than dodecane). We showcase the physical mechanism and universal behavior of droplet surface caving in leading to the inception and growth of ligaments. The caving of the top surface is governed by a balance between the acoustic pressure field and the restrictive surface tension of the droplet. The universal collapse of caving profiles for different benzene concentration (<70 % by volume) is shown by using an appropriate time scale obtained from force balance. Continuous caving leads to the formation of a liquid membrane-type structure which undergoes radial extension due to inertia gained during the precursor phase. The membrane subsequently closes at the rim and the kinetic energy leads to ligament formation and growth. Subsequent ligament breakup is primarily Rayleigh-Plateau type. The breakup mode shifts to diffusional entrapment-induced boiling with an increase in concentration of the volatile component (benzene >70 % by volume). The findings are portable to any similar bicomponent systems with differential volatility.

  10. Deformation and Break-up of Suspension Droplets Sheared in an Immiscible Fluid

    NASA Astrophysics Data System (ADS)

    Desse, Melinda; Hill, Sandra E.; Mitchell, John R.; Wolf, Bettina; Budtova, Tatiana

    2008-07-01

    The deformation and break-up behaviour of suspension droplets immersed in an immiscible fluid has not been widely studied albeit such systems are frequently encountered in every day multiphase products such as foods and cosmetics. Starch is a common thickener used in the food industry. Starch suspensions have shown to offer better flavour perception than polymer thickened solutions; a better understanding of their behaviour under flow would be beneficial in terms of advancement on product formulation. Deformation and break-up of a droplet of swollen-in-water starch granules placed in high viscosity silicon oil was visualised using a counter-rotating parallel-plate shear cell. The silicon oil had a high viscosity to induce shear stresses high enough to deform the droplet; it is also transparent and inert towards the studied system. The starch suspension was prepared to have a volume fraction of 100% swollen granules, i.e. that all water was bound within the swollen starch granules. The shear flow behaviour of this starch suspension is characterised by an apparent yield stress, shear-thinning and first normal stress differences. The rheo-optical experiments were conducted as start-up flow experiments applying shear stresses above the apparent yield stress. A constant shear stress throughout the experiment allows a constant viscosity of the droplet and therefore rules out the shear thinning aspect. Analysis showed droplet break-up at critical Capillary numbers close to those reported for Newtonian fluids. The results demonstrate that the droplet break-up behaviour in a complex emulsion system submitted to shear flow may not be fully described by the rheology of the individual phases alone but may require a microstructure component.

  11. Mantle exhumation and OCT architecture dependency on lithosphere deformation modes during continental breakup: Numerical experiments

    NASA Astrophysics Data System (ADS)

    Jeanniot, Ludovic; Kusznir, Nick; Manatschal, Gianreto; Cowie, Leanne

    2013-04-01

    The initiation of sea-floor spreading, during the continental breakup process, requires both the rupture of the continental crust and the initiation of decompression melting. This process results in mantle upwelling and at some point decompressional melting which creates new oceanic crust. Using numerical experiments, we investigate how the deformation mode of continental lithosphere thinning and stretching controls the rupture of continental crust and lithospheric mantle, the onset of decompression melting, their relative timing, and the circumstances under which mantle exhumation may occur. We assume that the topmost continental and ocean lithosphere, corresponding to the cooler brittle seismogenic layer, deforms by extensional faulting (pure-shear deformation) and magmatic intrusion, consistent with the observations of deformation processes occurring at slow spreading ocean ridges (Cannat, 1996). We assume that deformation beneath this topmost lithosphere layer (approximately 15-20 km thick) occurs in response to passive upwelling and thermal and melt buoyancy driven small-scale convection. We use a 2D finite element viscous flow model (FeMargin) to describe lithosphere and asthenosphere deformation. This flow field is used to advect lithosphere and asthenosphere temperature and material. The finite element model is kinematically driven by Vx for the topmost upper crust inducing passive upwelling beneath that layer. A vertical velocity Vz is defined for buoyancy enhanced upwelling as predicted by Braun et al. (2000). Melt generation is predicted by decompression melting using the parameterization and methodology of Katz et al. (2003). Numerical experiments have been used to investigate the dependency of continental crust and lithosphere rupture, decompression melt initiation, rifted margin ocean-continent transition architecture and subsidence history on the half-spreading rate Vx, buoyancy driven upwelling rate Vz, the relative contribution of these deformation

  12. Constraining lithosphere deformation modes during continental breakup for the Iberia-Newfoundland conjugate rifted margins

    NASA Astrophysics Data System (ADS)

    Jeanniot, Ludovic; Kusznir, Nick; Mohn, Geoffroy; Manatschal, Gianreto; Cowie, Leanne

    2016-06-01

    A kinematic model of lithosphere and asthenosphere deformation has been used to investigate lithosphere stretching and thinning modes during continental rifting leading to breakup and seafloor spreading. The model has been applied to two conjugate profiles across the Iberia-Newfoundland rifted margins and quantitatively calibrated using observed present-day water loaded subsidence and crustal thickness, together with observed mantle exhumation, subsidence and melting generation histories. The kinematic model uses an evolving prescribed flow-field to deform the lithosphere and asthenosphere leading to lithospheric breakup from which continental crustal thinning, lithosphere thermal evolution, decompression melt initiation and subsidence are predicted. We explore the sensitivity of model predictions to extension rate history, deformation migration and buoyancy induced upwelling. The best fit calibrated models of lithosphere deformation evolution for the Iberia-Newfoundland conjugate margins require; (1) an initial broad region of lithosphere deformation with passive upwelling, (2) lateral migration of deformation, (3) an increase in extension rate with time, (4) focussing of the deformation and (5) buoyancy induced upwelling. The model prediction of exhumed mantle at the Iberia-Newfoundland margins, as observed, requires a critical threshold of melting to be exceeded before melt extraction. The preferred calibrated models predict faster extension rates and earlier continental crustal separation and mantle exhumation for the Iberia Abyssal Plain-Flemish Pass conjugate margin profile than for the Galicia Bank-Flemish Cap profile to the north. The predicted N-S differences in the deformation evolution give insights into the 3D evolution of Iberia-Newfoundland margin crustal separation.

  13. Drop deformation and breakup in a partially filled horizontal rotating cylinder

    NASA Astrophysics Data System (ADS)

    White, Andrew; Pereira, Caroline; Hyacinthe, Hyaquino; Ward, Thomas

    2014-11-01

    Drop deformation and breakup due to shear flow has been studied extensively in Couette devices as well as in gravity-driven flows. In these cases shear is generated either by the moving wall or the drop's motion. For such flows the drop shape remains unperturbed at low capillary number (Ca), deforms at moderate Ca , and can experience breakup as Ca --> 1 and larger. Here single drops of NaOH(aq) will be placed in a horizontal cylindrical rotating tank partially filled with vegetable oil resulting in 10-2 < Ca <101 . It will be shown that the reactive vegetable oil-NaOH(aq) system, where surfactants are produced in situ by saponification, can yield lower minimum surface tensions and faster adsorption than non-reactive surfactant systems. Oil films between the wall and drop as well as drop shape will be observed as rotation rates and NaOH(aq) concentration are varied. Results will be presented in the context of previous work on bubble and drop shapes and breakup. NSF CBET #1262718.

  14. Theory of the deformation of aligned polyethylene

    PubMed Central

    Hammad, A.; Swinburne, T. D.; Hasan, H.; Del Rosso, S.; Iannucci, L.; Sutton, A. P.

    2015-01-01

    Solitons are proposed as the agents of plastic and viscoelastic deformation in aligned polyethylene. Interactions between straight, parallel molecules are mapped rigorously onto the Frenkel–Kontorova model. It is shown that these molecular interactions distribute an applied load between molecules, with a characteristic transfer length equal to the soliton width. Load transfer leads to the introduction of tensile and compressive solitons at the chain ends to mark the onset of plasticity at a well-defined yield stress, which is much less than the theoretical pull-out stress. Interaction energies between solitons and an equation of motion for solitons are derived. The equation of motion is based on Langevin dynamics and the fluctuation–dissipation theorem and it leads to the rigorous definition of an effective mass for solitons. It forms the basis of a soliton dynamics in direct analogy to dislocation dynamics. Close parallels are drawn between solitons in aligned polymers and dislocations in crystals, including the configurational force on a soliton. The origins of the strain rate and temperature dependencies of the viscoelastic behaviour are discussed in terms of the formation energy of solitons. A failure mechanism is proposed involving soliton condensation under a tensile load. PMID:26339196

  15. Deformation and breakup of micro- and nanoparticle stabilized droplets in microfluidic extensional flows.

    PubMed

    Mulligan, Molly K; Rothstein, Jonathan P

    2011-08-16

    Using a microfluidic flow-focusing device, monodisperse water droplets in oil were generated and their interface populated by either 1 μm or 500 nm amine modified silica particles suspended in the water phase. The deformation and breakup of these Pickering droplets were studied in both pure extensional flow and combined extensional and shear flow at various capillary numbers using a microfluidic hyperbolic contraction. The shear resulted from droplet confinement and increased with droplet size and position along the hyperbolic contraction. Droplet deformation was found to increase with increasing confinement and capillary number. At low confinements and low capillary numbers, the droplet deformation followed the predictions of theory. For fully confined droplets, where the interface was populated by 1 μm silica particles, the droplet deformation increased precipitously and two tails were observed to form at the rear of the droplet. These tails were similar to those seen for surfactant covered droplets. At a critical capillary number, daughter droplets were observed to stream from these tails. Due to the elasticity of the particle-laden interface, these drops did not return to a spherical shape, but were observed to buckle. Although increases in droplet deformation were observed, no tail streaming occurred for the 500 nm silica particle covered droplets over the range of capillary numbers studied.

  16. Deformation and breakup of a non-Newtonian slender drop in an extensional flow: inertial effects and stability

    NASA Astrophysics Data System (ADS)

    Favelukis, Moshe; Lavrenteva, Olga M.; Nir, Avinoam

    2006-09-01

    We consider the deformation and breakup of a non-Newtonian slender drop in a Newtonian liquid, subject to an axisymmetric extensional flow, and the influence of inertia in the continuous phase. The non-Newtonian fluid inside the drop is described by the simple power-law model and the unsteady deformation of the drop is represented by a single partial differential equation. The steady-state problem is governed by four parameters: the capillary number; the viscosity ratio; the external Reynolds number; and the exponent characterizing the power-law model for the non-Newtonian drop. For Newtonian drops, as inertia increases, drop breakup is facilitated. However, for shear thinning drops, the influence of increasing inertia results first in preventing and then in facilitating drop breakup. Multiple stationary solutions were also found and a stability analysis has been performed in order to distinguish between stable and unstable stationary states.

  17. Rotating Rig Development for Droplet Deformation/Breakup and Impact Induced by Aerodynamic Surfaces

    NASA Technical Reports Server (NTRS)

    Feo, A.; Vargas, M.; Sor, A.

    2012-01-01

    This work presents the development of a Rotating Rig Facility by the Instituto Nacional de Tecnica Aeroespacial (INTA) in cooperation with the NASA Glenn Research Center. The facility is located at the INTA installations near Madrid, Spain. It has been designed to study the deformation, breakup and impact of large droplets induced by aerodynamic bodies. The importance of these physical phenomena is related to the effects of Supercooled Large Droplets in icing clouds on the impinging efficiency of the droplets on the body, that may change should these phenomena not be taken into account. The important variables and the similarity parameters that enter in this problem are presented. The facility's components are described and some possible set-ups are explained. Application examples from past experiments are presented in order to indicate the capabilities of the new facility.

  18. A droplet deformation and breakup model based on virtual work principle

    NASA Astrophysics Data System (ADS)

    Sichani, Arash B.; Emami, Mohsen D.

    2015-03-01

    A new method of modeling the deformation and secondary breakup of a droplet is presented. The general formulation is based on the virtual work principle and potential flow assumption. To reach the final model, some approximations are made in the aerodynamic calculations including moderate Reynolds number of gas, Reg ˜ 1000, and high density ratio of liquid to gas phase, ρl/ρg ≫ 1. The dynamics of a drop is considered using two degrees of freedom. Two coupled ordinary differential equations are derived which describe time evolution of drop within both vibrational and bag regimes. The model is capable of keeping track of droplet deformation and distortion up to the onset of the bag rupture. The critical Weber number has been predicted with an error of around 20% as compared to the experimental data. The model performance is enhanced after a minor tuning, which result in the critical Weber number of 12.5. The predicted distortion quantities in lateral and longitudinal directions, as well as the drop profiles, are validated against experiments for bag and vibrational regimes. A good agreement is found between the computed results and experiments. Overall, achievements of the present work indicate a promising potential of the current approach for modeling droplet dynamics.

  19. Effects of insoluble surfactants on the nonlinear deformation and breakup of stretching liquid bridges

    NASA Astrophysics Data System (ADS)

    Ambravaneswaran, Bala; Basaran, Osman A.

    1999-05-01

    During the emission of single drops and the atomization of a liquid from a nozzle, threads of liquid are stretched and broken. A convenient setup for studying in a controlled manner the dynamics of liquid threads is the so-called liquid bridge, which is created by holding captive a volume of liquid between two solid disks and pulling apart the two disks at a constant velocity. Although the stability of static bridges and the dynamics of stretching bridges of pure liquids have been extensively studied, even a rudimentary understanding of the dynamics of the stretching and breakup of bridges of surfactant-laden liquids is lacking. In this work, the dynamics of a bridge of a Newtonian liquid containing an insoluble surfactant are analyzed by solving numerically a one-dimensional set of equations that results from a slender-jet approximation of the Navier-Stokes system that governs fluid flow and the convection-diffusion equation that governs surfactant transport. The computational technique is based on the method-of-lines, and uses finite elements for discretization in space and finite differences for discretization in time. The computational results reveal that the presence of an insoluble surfactant can drastically alter the physics of bridge deformation and breakup compared to the situation in which the bridge is surfactant free. They also make clear how the distribution of surfactant along the free surface varies with stretching velocity, bridge geometry, and bulk and surface properties of the liquid bridge. Gradients in surfactant concentration along the interface give rise to Marangoni stresses which can either retard or accelerate the breakup of the liquid bridge. For example, a high-viscosity bridge being stretched at a low velocity is stabilized by the presence of a surfactant of low surface diffusivity (high Peclet number) because of the favorable influence of Marangoni stresses on delaying the rupture of the bridge. This effect, however, can be lessened or

  20. Effects of insoluble surfactants on the nonlinear deformation and breakup of stretching liquid bridges

    SciTech Connect

    Ambravaneswaran, B.; Basaran, O.A.

    1999-05-01

    During the emission of single drops and the atomization of a liquid from a nozzle, threads of liquid are stretched and broken. A convenient setup for studying in a controlled manner the dynamics of liquid threads is the so-called liquid bridge, which is created by holding captive a volume of liquid between two solid disks and pulling apart the two disks at a constant velocity. Although the stability of static bridges and the dynamics of stretching bridges of pure liquids have been extensively studied, even a rudimentary understanding of the dynamics of the stretching and breakup of bridges of surfactant-laden liquids is lacking. In this work, the dynamics of a bridge of a Newtonian liquid containing an insoluble surfactant are analyzed by solving numerically a one-dimensional set of equations that results from a slender-jet approximation of the Navier{endash}Stokes system that governs fluid flow and the convection-diffusion equation that governs surfactant transport. The computational technique is based on the method-of-lines, and uses finite elements for discretization in space and finite differences for discretization in time. The computational results reveal that the presence of an insoluble surfactant can drastically alter the physics of bridge deformation and breakup compared to the situation in which the bridge is surfactant free. They also make clear how the distribution of surfactant along the free surface varies with stretching velocity, bridge geometry, and bulk and surface properties of the liquid bridge. Gradients in surfactant concentration along the interface give rise to Marangoni stresses which can either retard or accelerate the breakup of the liquid bridge. For example, a high-viscosity bridge being stretched at a low velocity is stabilized by the presence of a surfactant of low surface diffusivity (high Peclet number) because of the favorable influence of Marangoni stresses on delaying the rupture of the bridge. This effect, however, can be

  1. Interpretation of Coulomb breakup of {sup 31}Ne in terms of deformation

    SciTech Connect

    Hamamoto, Ikuko

    2010-02-15

    The recent experimental data on Coulomb breakup of the nucleus {sup 31}Ne are interpreted in terms of deformation. The measured large one-neutron removal cross section indicates that the ground state of {sup 31}Ne is either an s halo or a p halo. The data can be most easily interpreted as the spin of the ground state being 3/2{sup -} coming from either the Nilsson level [330 1/2] or the Nilsson level [321 3/2] depending on the neutron separation energy S{sub n}. However, the possibility of 1/2{sup +} coming from [200 1/2] is not excluded. It is suggested that if the large ambiguity in the measured value of S{sub n} of {sup 31}Ne, 0.29+-1.64 MeV, can be reduced by an order of magnitude, say to be +-100 keV, one may get a clear picture of the spin-parity of the halo ground state.

  2. Numerical simulation of drop deformations and breakup modes caused by direct current electric fields

    NASA Astrophysics Data System (ADS)

    Paknemat, H.; Pishevar, A. R.; Pournaderi, P.

    2012-10-01

    A drop suspended in another fluid shows different dynamic behaviors in an electric field that depends on its physical properties. The phenomenon of drop deformation under the application of an electric field, in the absence of a net volume charge, is simply caused by the surface stresses. Therefore, an accurate method is required for numerical modeling of the electric driving force at the interface to handle all of the discontinuities involved in the model. For this purpose, in this study the level set method is used along with the ghost fluid method to investigate the responses of three types of drop in the presence of an electric field. Moreover, to demonstrate the accuracy of the method, the breakup modes of each electric model are carefully simulated. Finally, the results of the simulations are compared with similar numerical and experimental results from the literature. The simulation results indicate the accuracy of the method for modeling of the phenomenon over a wide range of electric capillary numbers, and particularly for the capture of the drop profile at the instant of disintegration.

  3. Experimental Observations on the Deformation and Breakup of Water Droplets Near the Leading Edge of an Airfoil

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Feo, Alex

    2011-01-01

    This work presents the results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. An airfoil model placed at the end of the rotating arm was moved at speeds of 50 to 90 m/sec. A monosize droplet generator was employed to produce droplets that were allowed to fall from above, perpendicular to the path of the airfoil at a given location. High speed imaging was employed to observe the interaction between the droplets and the airfoil. The high speed imaging allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. A tracking software program was used to measure from the high speed movies the horizontal and vertical displacement of the droplet against time. The velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of a given droplet from beginning of deformation to breakup and/or hitting the airfoil. Results are presented for droplets with a diameter of 490 micrometers at airfoil speeds of 50, 60, 70, 80 and 90 m/sec

  4. Using crustal thickness and subsidence history on the Iberia-Newfoundland margins to constrain lithosphere deformation modes during continental breakup

    NASA Astrophysics Data System (ADS)

    Jeanniot, Ludovic; Kusznir, Nick; Manatschal, Gianreto; Mohn, Geoffroy

    2014-05-01

    Observations at magma-poor rifted margins such as Iberia-Newfoundland show a complex lithosphere deformation history during continental breakup and seafloor spreading initiation leading to complex OCT architecture with hyper-extended continental crust and lithosphere, exhumed mantle and scattered embryonic oceanic crust and continental slivers. Initiation of seafloor spreading requires both the rupture of the continental crust and lithospheric mantle, and the onset of decompressional melting. Their relative timing controls when mantle exhumation may occur; the presence or absence of exhumed mantle provides useful information on the timing of these events and constraints on lithosphere deformation modes. A single lithosphere deformation mode leading to continental breakup and sea-floor spreading cannot explain observations. We have determined the sequence of lithosphere deformation events for two profiles across the present-day conjugate Iberia-Newfoundland margins, using forward modelling of continental breakup and seafloor spreading initiation calibrated against observations of crustal basement thickness and subsidence. Flow fields, representing a sequence of lithosphere deformation modes, are generated by a 2D finite element viscous flow model (FeMargin), and used to advect lithosphere and asthenosphere temperature and material. FeMargin is kinematically driven by divergent deformation in the upper 15-20 km of the lithosphere inducing passive upwelling beneath that layer; extensional faulting and magmatic intrusions deform the topmost upper lithosphere, consistent with observations of deformation processes occurring at slow spreading ocean ridges (Cannat, 1996). Buoyancy enhanced upwelling, as predicted by Braun et al. (2000) is also kinematically included in the lithosphere deformation model. Melt generation by decompressional melting is predicted using the parameterization and methodology of Katz et al. (2003). The distribution of lithosphere deformation, the

  5. Dependency of continental crustal rupture, decompression melt initiation and OCT architecture on lithosphere deformation modes during continental breakup: Numerical experiments

    NASA Astrophysics Data System (ADS)

    Jeanniot, L.; Kusznir, N. J.; Manatschal, G.

    2012-12-01

    During the continental breakup process, the initiation of sea-floor spreading requires both the rupture of the continental crust and the initiation of decompression melting. Using numerical experiments, we investigate how the deformation mode of continental lithosphere thinning and stretching controls the rupture of continental crust and lithospheric mantle, the onset of decompression melting and their relative timing. We use a two dimensional finite element viscous flow model to describe lithosphere and asthenosphere deformation. This flow field is used to advect lithosphere and asthenosphere material and temperature. Decompression melting is predicted using the parameterization scheme of Katz et al. (2003). Consistent with the observations of deformation processes occurring at slow spreading ocean ridges (Cannat, 1996), we assume that the topmost continental and oceanic lithosphere, corresponding to the cooler brittle seismogenic layer, deforms by extensional faulting (which we approximate to pure-shear deformation) and magmatic intrusion. Beneath this topmost lithosphere layer approximately 15-20 km thick, we assume that deformation occurs in response to passive upwelling and thermal and melt buoyancy driven small-scale convection. The relative contribution of these deformation components is parameterised by the ratio Vz/Vx, where Vx is the half spreading rate applied to the topmost lithosphere deformation and Vz is the upwelling velocity associated with the small scale convection. We use a series of numerical experiments to investigate the dependency of continental crust and lithosphere rupture, decompression melt initiation, rifted margin ocean-continent transition architecture and subsidence history on the half-spreading rate Vx, buoyancy driven upwelling rate Vz, the ratio Vz/Vx and upper lithosphere pure-shear width W. Based on the numerical experiment results we explore a polyphase evolution of deformation modes leading to continental breakup, sea

  6. Determination of Impact Parameters in Aligned Breakup of Projectile-like Fragments in $^{197}$Au + $^{197}$Au Collisions at 23$A$MeV

    SciTech Connect

    Cap, T.; Siwek-Wilczyńska, K.; Wilczynski, J.; Auditore, L.; Cardella, G.; De Filippo, E.; Geraci, E.; Grassi, L.; Grzeszczuk, A.; La Guidara, E.; Han, J.; Kozik, T.; Lanzalone, G.; Lombardo, I.; Najman, R.; Nicolis, N. G.; Pagano, A.; Papa, M.; Piasecki, E.; Pirrone, S.; Planeta, R.; Politi, G.; Rizzo, F.; Russotto, P.; Skwira-Chalot, I.; Trifiro, A.; Trimarchi, M.; Verde, G.; Zipper, W.

    2016-03-01

    Symmetric and asymmetric aligned breakup of projectile-like fragments in $^{197}$Au + $^{197}$Au collisions at 23$A$,MeV was studied. Independently of the asymmetry, the reaction yields have been found peaked at a common, very narrow range of impact parameters.

  7. Determination of Impact Parameters in Aligned Breakup of Projectile-like Fragments in $$^{197}$$Au + $$^{197}$$Au Collisions at 23$A$MeV

    DOE PAGES

    Cap, T.; Siwek-Wilczyńska, K.; Wilczynski, J.; ...

    2016-03-01

    Symmetric and asymmetric aligned breakup of projectile-like fragments inmore » $$^{197}$$Au + $$^{197}$$Au collisions at 23$A$,MeV was studied. Independently of the asymmetry, the reaction yields have been found peaked at a common, very narrow range of impact parameters.« less

  8. Modeling of drop breakup in the bag breakup regime

    NASA Astrophysics Data System (ADS)

    Wang, C.; Chang, S.; Wu, H.; Xu, J.

    2014-04-01

    Several analytic models for predicting the drop deformation and breakup have been developed over the last three decades, but modeling drop breakup in the bag-type regime is less reported. In this Letter, a breakup model has been proposed to predict the drop deformation length and breakup time in the bag-type breakup regime in a more accurate manner. In the present model, the drop deformation which is approximately as the displacement of the centre of mass (c. m.) along the axis located at the centre of the drop, and the movement of c. m. is obtained by solving the pressure balance equation. The effects of the drop deformation on the drop external aerodynamic force are considered in this model. Drop breakup occurs when the deformation length reaches the maximum value and the maximum deformation length is a function of Weber number. The performance and applicability of the proposed breakup model are tested against the published experimental data.

  9. The optical manifestation of dispersive field-aligned bursts in auroral breakup arcs

    NASA Astrophysics Data System (ADS)

    Dahlgren, H.; Semeter, J. L.; Marshall, R. A.; Zettergren, M.

    2013-07-01

    High-resolution optical observations of a substorm expansion show dynamic auroral rays with surges of luminosity traveling up the magnetic field lines. Observed in ground-based imagers, this phenomenon has been termed auroral flames, whereas the rocket signatures of the corresponding energy dispersions are more commonly known as field-aligned bursts. In this paper, observations of auroral flames obtained at 50 frames/s with a scientific-grade Complementary Metal Oxide Semiconductor (CMOS) sensor (30° × 30° field of view, 30 m resolution at 120 km) are used to provide insight into the nature of the precipitating electrons similar to high-resolution particle detectors. Thanks to the large field of view and high spatial resolution of this system, it is possible to obtain a first-order estimate of the temporal evolution in altitude of the volume emission rate from a single sensor. The measured volume emission rates are compared with the sum of modeled eigenprofiles obtained for a finite set of electron beams with varying energy provided by the TRANSCAR auroral flux tube model. The energy dispersion signatures within each auroral ray can be analyzed in detail during a fraction of a second. The evolution of energy and flux of the precipitation shows precipitation spanning over a large range of energies, with the characteristic energy dropping from 2.1 keV to 0.87 keV over 0.2 s. Oscillations at 2.4 Hz in the magnetic zenith correspond to the period of the auroral flames, and the acceleration is believed to be due to Alfvenic wave interaction with electrons above the ionosphere.

  10. Secondary breakup of coal water slurry drops

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Liu, Hai-Feng; Xu, Jian-Liang; Li, Wei-Feng

    2011-11-01

    To investigate secondary atomization of coal water slurry (CWS), deformation and breakup of eight kinds of CWS drops are presented using high speed digital camera. Based on morphology, deformation and breakup regimes of CWS drops can be termed some different modes: deformation, multimode breakup (including two sub-modes: hole breakup and tensile breakup), and shear breakup. Correlations on the ranges of breakup modes are also obtained. The conventional Weber number and Ohnesorge number are found to be insufficient to classify all breakup modes of CWS drops, so two other non-dimensional numbers based on rheology of CWS are suggested to use in the deformation and breakup regime map. Finally, total breakup time is studied and correlated, which increases with Ohnesorge number.

  11. Aligned breakup of heavy nuclear systems as a new type of deep inelastic collisions at small impact parameters

    SciTech Connect

    Wilczynski, J.; Swiderski, L.; Pagano, A.; Cardella, G.; De Filippo, E.; La Guidara, E.; Papa, M.; Pirrone, S.; Amorini, F.; Anzalone, A.; Cavallaro, S.; Colonna, M.; Di Toro, M.; Maiolino, C.; Porto, F.; Rizzo, F.; Russotto, P.; Auditore, L.

    2010-06-15

    An interesting process of violent reseparation of a heavy nuclear system into three or four fragments of comparable size was recently observed in {sup 197}Au+{sup 197}Au collisions at 15 MeV/nucleon. Combined analysis of the binary deep inelastic events and the ternary and quaternary breakup events demonstrates that the newly observed ternary and quaternary reactions belong to the same wide class of deep inelastic collisions as the conventional (binary) damped reactions. It is shown that the ternary and quaternary breakup reactions occur at extremely inelastic collisions corresponding to small impact parameters, while more peripheral collisions lead to well-known binary deep inelastic reactions.

  12. Directional Correlation of Nuclear-Collision Probability for Aligned Beams of Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Fukuda, Mitsunori; Tanaka, Masaomi; Yamaoka, Shintaro; Ohno, Junichi; Mihara, Mototsugu; Matsuta, Kensaku; Nishimura, Daiki; Yoshinaga, Kenta; Takechi, Maya; Ohtsubo, Takashi; Izumikawa, Takuji; Nagashima, Masayuki; Suzuki, Takeshi; Yamaguchi, Takayuki; Kitagawa, Atsushi; Sato, Shinji; Suzuki, Shinji; Fukuda, Shigekazu; Himac H093 Collaboration

    2014-09-01

    In the long history of nuclear physics, a lot of observables have been discussed in connection with the nuclear deformation. In this work, an investigation have been carried out on the directional correlation of the nuclear-collision probability between the direction of beam of deformed nuclei and the deformation axis, to sense the nuclear deformation directly. Few experimental studies of this kind have been done because of the difficulties in producing aligned beams. We utilized the projectile fragmentation to produce the aligned nuclear beams. We tested these measurements for 9Be, 10B, and 26Al at the HIMAC facility. By selecting the parallel momentum using the separator, spin aligned beams were produced, with which the interaction cross sections were measured. The cross sections were precisely measured as a function of longitudinal momentum. We will report on the details of measurements and discussions on this intriguing result.

  13. Using crustal thickness, subsidence and P-T-t history on the Iberia-Newfoundland & Alpine Tethys margins to constrain lithosphere deformation modes during continental breakup

    NASA Astrophysics Data System (ADS)

    Jeanniot, L.; Kusznir, N. J.; Manatschal, G.; Mohn, G.; Beltrando, M.

    2013-12-01

    Observations at magma-poor rifted margins such as Iberia-Newfoundland show a complex lithosphere deformation history and OCT architecture, resulting in hyper-extended continental crust and lithosphere, exhumed mantle and scattered embryonic oceanic crust before continental breakup and seafloor spreading. Initiation of seafloor spreading requires both the rupture of the continental crust and lithospheric mantle, and the onset of decompressional melting. Their relative timing controls when mantle exhumation may occur; the presence or absence of exhumed mantle provides useful information on the timing of these events and constraints on lithosphere deformation modes. A single kinematic lithosphere deformation mode leading to continental breakup and sea-floor spreading cannot explain observations. We have determined the sequence of lithosphere deformation events, using forward modelling of crustal thickness, subsidence and P-T-t history calibrated against observations on the present-day Iberia-Newfoundland and the fossil analogue Alpine Tethys margins. Lithosphere deformation modes, represented by flow fields, are generated by a 2D finite element viscous flow model (FeMargin), and used to advect lithosphere and asthenosphere temperature and material. FeMargin is kinematically driven by divergent deformation in the topmost upper lithosphere inducing passive upwelling beneath that layer; the upper lithosphere is assumed to deform by extensional faulting and magmatic intrusions, consistent with observations of deformation processes occurring at slow spreading ocean ridges (Cannat, 1996). Buoyancy enhanced upwelling is also included in the kinematic model as predicted by Braun et al (2000). We predict melt generation by decompressional melting using the parameterization and methodology of Katz et al., 2003. We use a series of numerical experiments, tested and calibrated against crustal thicknesses and subsidence observations, to determine the distribution of lithosphere

  14. Theory and simulation of the dynamics, deformation, and breakup of a chain of superparamagnetic beads under a rotating magnetic field

    NASA Astrophysics Data System (ADS)

    Vázquez-Quesada, A.; Franke, T.; Ellero, M.

    2017-03-01

    In this work, an analytical model for the behavior of superparamagnetic chains under the effect of a rotating magnetic field is presented. It is postulated that the relevant mechanisms for describing the shape and breakup of the chains into smaller fragments are the induced dipole-dipole magnetic force on the external beads, their translational and rotational drag forces, and the tangential lubrication between particles. Under this assumption, the characteristic S-shape of the chain can be qualitatively understood. Furthermore, based on a straight chain approximation, a novel analytical expression for the critical frequency for the chain breakup is obtained. In order to validate the model, the analytical expressions are compared with full three-dimensional smoothed particle hydrodynamics simulations of magnetic beads showing excellent agreement. Comparison with previous theoretical results and experimental data is also reported.

  15. Latest stages of deformation leading to breakup of the Australian-Antarctic rifted margins: new constraints from deep seismic observations and potential data.

    NASA Astrophysics Data System (ADS)

    Gillard, Morgane; Autin, Julia; Manatschal, Gianreto; Sauter, Daniel; Munschy, Marc; Schaming, Marc

    2014-05-01

    The discovery of large domains of hyper-extended continental crust and exhumed mantle along many present-day magma-poor rifted margins questions the existing models proposed to explain lithospheric breakup and onset of seafloor spreading. In particular, the amount of magma and its relation to tectonic structures is yet little understood. Trying to find answers to these questions asks to work in the most distal parts of rifted margins where the latest stage of rifting occurred and the first steady state oceanic crust was emplaced. In this aim, the Australian-Antarctic conjugated margins provide an excellent study area. Indeed, the central sector of the Great Australian Bight/Wilkes Land developed in a magma-poor probably ultra-slow setting and displays a complex and not yet well understood Ocean-Continent Transition (OCT). This distal area is well imaged by numerous high quality seismic lines covering the whole OCT and the steady-state oceanic crust. Our seismic observations allow the recognition of different tectono-sedimentary units and magmatic additions. The relation between the sedimentary units, magmatic additions and the tectonic structures enable to define a complex interaction between these processes indicating a clear polyphase evolution of rifting and migration of the deformation towards the area of future breakup. The migration of deformation is well imaged by the fact that each tectono-sedimentary unit "downlaps" oceanwards onto "new" basement, which enables to define basement units that become younger oceanwards. This observation suggests that final rifting is associated with the creation of new "basement" under conditions that are not yet those of a steady state oceanic crust. We propose that two major detachment systems are responsible for mantle exhumation forming this new basement. In particular, they can explain the different deformation phases observed in the tectono-sedimentary sequences and related magmatic additions. It appears that the

  16. Proximally placed alignment control strap for ankle varus deformity: a case report.

    PubMed

    Oh-Park, Mooyeon; Park, Geun Young; Hosamane, Sadvi; Kim, Dennis D

    2007-01-01

    Ankle varus is a commonly encountered deformity in patients with neurologic or musculoskeletal disorders. It impedes stability during the stance phase of gait and often causes skin lesions on the lateral ankle area. Plastic or conventional ankle-foot orthoses (AFOs) with supplementary features such as a T-strap or increased contact area of the lateral flange have been used for correctable varus deformities. These supplementary modifications, however, have limitations as effective tools for varus control, and ankle varus may persist despite their use. We are revisiting the concept of a proximally placed alignment control strap for ankle varus, which may overcome the limitations of currently available modifications. This alignment control strap is designed to provide a medially directed force on the tibia and fibula against the force of varus deformation of the ankle. This modification can be easily added to various types of existing AFOs with acceptable aesthetic appearance. We describe 2 cases of manually correctable but persistent varus deformities of the ankle that were successfully controlled by utilization of the proximally placed alignment control strap.

  17. Integrated random-aligned carbon nanotube layers: deformation mechanism under compression

    NASA Astrophysics Data System (ADS)

    Zeng, Zhiping; Gui, Xuchun; Gan, Qiming; Lin, Zhiqiang; Zhu, Yuan; Zhang, Wenhui; Xiang, Rong; Cao, Anyuan; Tang, Zikang

    2014-01-01

    Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial compression with a large range of strain and cyclic testing. Integrated nanotube layers deform sequentially with different mechanisms due to the distinct morphology of each layer. While the aligned layer forms buckles under compression, nanotubes in the random layer tend to be parallel and form bundles, resulting in the integration of quite different properties (strength and stiffness) and correspondingly distinct plateau regions in the stress-strain curves. Our results indicate a great promise of constructing hierarchical carbon nanotube structures with tailored energy absorption properties, for applications such as cushioning and buffering layers in microelectromechanical systems.Carbon nanotubes have the potential to construct highly compressible and elastic macroscopic structures such as films, aerogels and sponges. The structure-related deformation mechanism determines the mechanical behavior of those structures and niche applications. Here, we show a novel strategy to integrate aligned and random nanotube layers and reveal their deformation mechanism under uniaxial compression with a large range of strain and cyclic testing. Integrated nanotube layers deform sequentially with different mechanisms due to the distinct morphology of each layer. While the aligned layer forms buckles under compression, nanotubes in the random layer tend to be parallel and form bundles, resulting in the integration of quite different properties (strength and stiffness) and correspondingly distinct plateau regions in the stress-strain curves. Our results indicate a great promise of

  18. Sagittal alignment of the first metatarsophalangeal joint after arthrodesis for rheumatoid forefoot deformity.

    PubMed

    Tanabe, Akihiko; Majima, Tokifumi; Onodera, Tomohiro; Sawaguchi, Naohiro; Watanabe, Takuya; Kasahara, Yasuhiko; Takahashi, Daisuke

    2013-01-01

    The present study assessed the midterm results of reconstruction for rheumatoid forefoot deformity with arthrodesis of the first metatarsophalangeal (MTP) joint, scarf osteotomy, resection arthroplasty of the metatarsal head of the lesser toes, and surgical repair of hammertoe deformity (arthrodesis of the proximal interphalangeal joint). Special focus was placed on the sagittal alignment of the first metatarsophalangeal joint after arthrodesis. We retrospectively evaluated the postoperative clinical outcomes and radiographic findings for 16 consecutive female patients (20 feet) with symptomatic rheumatoid forefoot deformities. The mean duration of follow-up was 7.9 (range 4 to 13) years. All first MTP joints and first metatarsal bones were fused successfully. The mean value of the American Orthopaedic Foot and Ankle Society and Japanese Society for Foot Surgery clinical scores significantly improved overall, except for 2 patients (10%), who complained of first toe pain at the final follow-up visit owing to sagittal misalignment of the fused first MTP joint. Sagittal alignment of the first metatarsal varies greatly because of the rheumatoid midfoot and hindfoot deformities. Therefore, inclination of the first metatarsal should be considered when determining the first MTP joint sagittal fusion angle.

  19. The Relationship Between Cervical Degeneration and Global Spinal Alignment in Patients With Adult Spinal Deformity.

    PubMed

    Fujimori, Takahito; Le, Hai; Schairer, William; Inoue, Shinichi; Iwasaki, Motoki; Oda, Takenori; Hu, Serena S

    2017-05-01

    To examine the relationship between cervical degeneration and spinal alignment by comparing patients with adult spinal deformity versus the control cohort. The effect of degeneration on cervical alignment has been controversial. Cervical and full-length spine radiographs of 57 patients with adult spinal deformity and 78 patients in the control group were reviewed. Adult spinal deformity was classified into 3 types based on the primary characteristics of the deformity: "Degenerative flatback" group, "Positive sagittal imbalance" group, and "Hyperthoracic kyphosis" group. Cervical degeneration was assessed using the cervical degeneration index scoring system. The "Degenerative flatback" group had significantly higher total cervical degeneration index score (25±7) than the control group (16±8), the "Positive sagittal imbalance" group (18±8), and the "Hyperthoracic kyphosis" group (12±7) (P<0.01). The "Degenerative flatback" group had significantly less cervical lordosis than the other groups. This reduced amount of cervical lordosis was thought to be induced by a compensatory decrease in thoracic kyphosis. In this group, increased cervical degeneration was significantly associated with a decrease in cervical lordosis. Significantly greater compensatory increase in cervical lordosis was noted in the "Positive sagittal imbalance" group (20±15 degrees) and the "Hyperthoracic kyphosis" group (26±9 degrees) compared with the control group (11±12 degrees) (P<0.02). Flat cervical spine coexisted with cervical degeneration when compensatory hypothoracic kyphosis was induced by degenerative flatback. In other situations, cervical lordosis could increase as a compensatory reaction against sagittal imbalance or hyperthoracic kyphosis.

  20. Natural history of spinopelvic alignment differs from symptomatic deformity of the spine.

    PubMed

    Mendoza-Lattes, Sergio; Ries, Zachary; Gao, Yubo; Weinstein, Stuart L

    2010-07-15

    Cross-sectional study and systematic review of the literature. Describe the natural history of spinopelvic alignment parameters and their behavior in patients with degenerative spinal deformity. Normal stance and gait requires congruence between the spine-sacrum and pelvis-lower extremities. This is determined by the pelvic incidence (PI), and 2 positional parameters, the pelvic tilt, and sacral slope (SS). The PI also affects lumbar lordosis (LL), a positional parameter. The final goal is to position the body's axis of gravity to minimize muscle activity and energy consumption. Two study cohorts were recruited: 32 healthy teenagers (Risser IV-V) and 54 adult patients with symptomatic spinal deformity. Standing radiographs were used to measure spinopelvic alignment and positional parameters (SS, PI, sacral-femoral distance [SFD], C7-plumbline [C7P], LL, and thoracic kyphosis). Data from comparable groups of asymptomatic individuals were obtained from the literature. PI increases linearly with age (r2 = 0.8646) and is paralleled by increasing SFD (r2 = 0.8531) but not by SS. Patients with symptomatic deformity have higher SFD (42 +/- 13.6 mm vs. 63.6 +/- 21.6 mm; P < 0.001) and lower SS (42 degrees +/- 9.6 degrees vs. 30.7 degrees +/- 13.6 degrees; P < 0.001) but unchanged PI. The C7P also presents a linear increase throughout life (r2 = 0.8931), and is significantly increased in patients with symptomatic deformity (40 +/- 37 mm vs. 70.3 +/- 59.5 mm; P < 0.001). First, Gradual increase in PI is described throughout the lifespan that is paralleled by an increase in SFD, and is not by an increase in the SS. This represents a morphologic change of the pelvis. Second, Patients with symptomatic deformity of the spine present an increased C7P, thoracic hypokyphosis, reduced LL, and signs of pelvic retroversion (decreased LL and SS; increased SFD).

  1. The Breakup

    ERIC Educational Resources Information Center

    Lum, Lydia

    2011-01-01

    This article reports on the breakup between Texas Southmost College (TSC) and the upper-division University of Texas at Brownsville (UTB). The split marks the official end of an unusual 20-year partnership between TSC and the University of Texas System that, for the first time, ushered four-year university education into overwhelmingly Latino…

  2. The influence of surfactant on the deformation and breakup of a viscous drop: The effect of surfactant solubility

    SciTech Connect

    Milliken, W.J. ); Leal, L.G. . Dept. of Chemical and Nuclear Engineering)

    1994-09-01

    The influence of surfactant on the deformation of a viscous drop in a uniaxial extensional flow is considered. Previous studies have examined the role in insoluble surfactant. Here, the authors examine soluble surfactant, i.e., surfactant that may be transferred between the interface and the continuous phase. The transfer of surfactant to and from the interface mitigates many of the effects observed with insoluble surfactant by diminishing the magnitude of surfactant gradients. In the presence of soluble surfactant, the deformation generally lies between that of insoluble surfactant and that of a drop with a constant and uniform coverage of surfactant. However, there are notable exceptions particularly at high surfactant activity. The influence of surfactant on the interfacial velocity of the drop is also explicitly considered. It is shown that while insoluble surfactant can substantially retard a drop interface, interphase surfactant transfer acts to remobilize the interface.

  3. Using subsidence and P-T-t history on the Alpine Tethys margin to constrain lithosphere deformation modes during continental breakup

    NASA Astrophysics Data System (ADS)

    Jeanniot, Ludovic; Kusznir, Nick; Manatschal, Gianreto; Mohn, Geoffroy; Beltrando, Marco

    2014-05-01

    Mantle exhumation and hyper-extended crust, as observed on the Iberia-Newfoundland conjugate margins, are key components of both present-day and fossil analogue magma-poor rifted margins. Conceptual models of the Alpine Tethys paleogeography evolution show a complex subsidence history, determined by the nature and composition of sedimentary, crustal and mantle rocks in the Alpine domains (Mohn et al., 2010). The relative timing of crustal rupture and decompressional melt initiation and inherited mantle composition control whether mantle exhumation may occur; the presence or absence of exhumed mantle therefore provides useful information on the timing of these events and constraints on lithosphere deformation modes and composition. A single mode of lithosphere deformation leading to continental breakup and sea-floor spreading cannot explain observations. We have determined the sequence of lithosphere deformation modes for the fossil Alpine Tethys margin using a numerical model of the temporal and spatial evolution of lithosphere deformation; the model has been calibrated against observations of subsidence and P-T-t history for the Alpine Tethys margin. A 2D finite element viscous flow model (FeMargin) is used to generate flow fields for a sequence of lithosphere deformation modes, which are used to advect lithosphere and asthenosphere temperature and material. FeMargin is kinematically driven by divergent deformation in the topmost 15-20 km of the lithosphere inducing passive upwelling beneath that layer; the upper lithosphere is assumed to deform by extensional faulting and magmatic intrusions, consistent with observations of deformation processes occurring at slow spreading ocean ridges (Cannat, 1996). We also include buoyancy enhanced upwelling in the kinematic model as proposed by Braun et al. (2000). We generate melt by decompressional melting using the parameterization and methodology of Katz et al. (2003). In the modelling of the Alpine Tethys margin

  4. Sagittal spino-pelvic alignment failures following three column thoracic osteotomy for adult spinal deformity.

    PubMed

    Lafage, Virginie; Smith, Justin S; Bess, Shay; Schwab, Frank J; Ames, Christopher P; Klineberg, Eric; Arlet, Vincent; Hostin, Richard; Burton, Douglas C; Shaffrey, Christopher I

    2012-04-01

    Three column thoracic osteotomy (TCTO) is effective to correct rigid thoracic deformities, however, reasons for residual postoperative spinal deformity are poorly defined. Our objective was to evaluate risk factors for poor spino-pelvic alignment (SPA) following TCTO for adult spinal deformity (ASD). Multicenter, retrospective radiographic analysis of ASD patients treated with TCTO. Radiographic measures included: correction at the osteotomy site, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt (PT), and pelvic incidence (PI). Final SVA and PT were assessed to determine if ideal SPA (SVA < 4 cm, PT < 25°) was achieved. Differences between the ideal (IDEAL) and failed (FAIL) SPA groups were evaluated. A total of 41 consecutive ASD patients treated with TCTO were evaluated. TCTO significantly decreased TK, maximum coronal Cobb angle, SVA and PT (P < 0.05). Ideal SPA was achieved in 32 (78%) and failed in 9 (22%) patients. The IDEAL and FAIL groups had similar total fusion levels and similar focal, SVA and PT correction (P > 0.05). FAIL group had larger pre- and post-operative SVA, PT and PI and a smaller LL than IDEAL (P < 0.05). Poor SPA occurred in 22% of TCTO patients despite similar operative procedures and deformity correction as patients in the IDEAL group. Greater pre-operative PT and SVA predicted failed post-operative SPA. Alternative or additional correction procedures should be considered when planning TCTO for patients with large sagittal global malalignment, otherwise patients are at risk for suboptimal correction and poor outcomes.

  5. Predictive Model for Cervical Alignment and Malalignment Following Surgical Correction of Adult Spinal Deformity.

    PubMed

    Passias, Peter G; Oh, Cheongeun; Jalai, Cyrus M; Worley, Nancy; Lafage, Renaud; Scheer, Justin K; Klineberg, Eric O; Hart, Robert A; Kim, Han Jo; Smith, Justin S; Lafage, Virginie; Ames, Christopher P

    2016-09-15

    Retrospective review of prospective multicenter database. Use predictive modeling to identify patient characteristics, radiographic, and surgical variables that predict reaching an outcome threshold of suboptimal cervical alignment after adult spinal deformity (ASD) surgery. Cervical deformity (CD) after ASD correction has been defined with the following criteria: T1S-CL>20°, C2-C7 SVA>40 mm, and/or C2-C7 kyphosis >10°. While studies have analyzed CD predictors, few have defined and identified predictors of optimal cervical alignment after thoracolumbar surgery. Inclusion criteria were surgical ASD patients with baseline and 2-year follow-up. Postoperative cervical alignment (CA) and malalignment (nonCA) at 2 years was defined with the following radiographic criteria: 0°≤T1S-CL≤20°, 0 mm≤C2-C7 SVA≤40 mm, or C2-C7 lordosis >0°. Three thresholds classifying malalignment were defined: (T1) missing 1 criterion, (T2) missing 2 criteria, (T3) missing 3 criteria. Multivariable logistic stepwise regression models with bootstrap resampling procedure were performed for demographic, surgical, and radiographic variables. The model was validated with receiver operative characteristic and area under the curve. Two hundred twenty-five surgical ASD patients were included. At 2 years 208 patients (92.4%) were grouped as CA in T3, while 17 (7.6%) were nonCA. Patients were similar in age (CA: 56.10 vs. nonCA: 55.78 years, P = 0.150), BMI (CA: 26.93 vs. nonCA: 26.94 kg/m, P = 0.716), and sex (CA: 76.5% vs. nonCA: 87.0%, P = 0.194). The final predictive model included C2 slope, C2-T3 CL, T1S-CL, C2-C7 CL, Pelvic Tilt, C2-S1 SVA, PI-LL, and Smith-Peterson osteotomies number. In this model (area under the curve 89.22% [97.49-80.96%]), the following variables were identified as predictors of nonCA: increased Smith-Peterson osteotomies use (OR: 1.336, P = 0.017), and C2-T3 angle (OR: 1.048, P = 0.005). This study created a statistical model that

  6. Maintenance of sagittal plane alignment after surgical correction of spinal deformity in patients with cerebral palsy.

    PubMed

    Sink, Ernest L; Newton, Peter O; Mubarak, Scott J; Wenger, Dennis R

    2003-07-01

    A case series of patients with cerebral palsy treated for spinal deformity using Luque-Galveston instrumentation was retrospectively analyzed. To analyze the incidence and risk factors for postoperative loss of sagittal plane correction initially obtained with Luque-Galveston instrumentation in patients with cerebral palsy. The Luque-Galveston instrumentation technique has been widely adopted in the treatment of neuromuscular spinal deformity. Although the results in the coronal plane have been generally satisfactory, problems in maintaining sagittal plane correction have been noted. For this study, 41 patients with spastic quadriplegia who underwent surgical correction of spinal deformity between 1990 and 1998 were reviewed with attention given to the maintenance of sagittal plane correction. Preoperative, initial postoperative, and most recent radiographs were measured to determine the sagittal Cobb angle from T5 to T12, T12 to L2, and L1 to S1. On the basis of the preoperative sagittal alignment, patients were separated into two groups: those with preoperative hyperkyphosis (T5-T12 >or= 50 degrees, T12-L2 >or= 20 degrees, or L1-S1 >or= 0 degrees ) and those with normal or decreased kyphosis. The radiographs were assessed for proximal hardware failure/pullout or junctional kyphosis (>20 degrees ), and for backing out of the Galveston rods distally. Of the 41 patients, 29 underwent correction of their deformity with Luque-Galveston instrumentation alone. In 21 of these patients anterior release-fusion preceded the posterior procedure. Additional anterior lumbar instrumentation was used in 12 patients. Proximal loss of correction or implant failure occurred in 13 patients (32%). In four of these patients junctional kyphosis developed at the cephalad extent of the instrumentation, and nine patients had proximal hardware failure/pullout. Posterior migration of the distal end of the Galveston rods occurred in five patients (12%). Four of these five patients had

  7. Light modulation in planar aligned short-pitch deformed-helix ferroelectric liquid crystals

    NASA Astrophysics Data System (ADS)

    Kotova, Svetlana P.; Samagin, Sergey A.; Pozhidaev, Evgeny P.; Kiselev, Alexei D.

    2015-12-01

    We study both experimentally and theoretically modulation of light in a planar aligned deformed-helix ferroelectric liquid crystal (DHFLC) cell with subwavelength helix pitch, which is also known as a short-pitch DHFLC. In our experiments, the azimuthal angle of the in-plane optical axis and electrically controlled parts of the principal in-plane refractive indices are measured as a function of voltage applied across the cell. Theoretical results giving the effective optical tensor of a short-pitch DHFLC expressed in terms of the smectic tilt angle and the refractive indices of the ferroelectric liquid crystal (FLC) are used to fit the experimental data. The optical anisotropy of the FLC material is found to be weakly biaxial. For both the transmissive and reflective modes, the results of fitting are applied to model the phase and amplitude modulation of light in the DHFLC cell. We demonstrate that if the thickness of the DHFLC layer is about 50 μ m , the detrimental effect of field-induced rotation of the in-plane optical axes on the characteristics of an axicon designed using the DHFLC spatial light modulator in the reflective mode is negligible.

  8. Mutual alignment errors analysis based on wavelet due to antenna deformations in inter-satellite laser communications

    NASA Astrophysics Data System (ADS)

    Xie, Wanqing; Tan, Liying; Ma, Jing

    2012-02-01

    Wavelet analysis is employed in the paper to model diversified optical antenna deformations in inter-satellite laser communications. Mutual alignment errors, which comprise pointing and tracking errors, caused by the deformations are investigated with the model. Theoretical and numerical analysis show that both errors increase with the dilation factor of the model. Tracking error increases monotonously with the shift factor of the model, while pointing error increases first, and then decreases. When the deformation can be well approximated to a constant, both errors fluctuate periodically with the coefficient of the model. Otherwise, there is no obvious regularity for both errors with the increase of the coefficient. A reference for the machining precision of optical antennas is presented, and a method to reduce the effect of deformations is recommended. It is hoped that the study can contribute to improve the performance of inter-satellite laser communication systems.

  9. Surviving Atmospheric Spacecraft Breakup

    NASA Technical Reports Server (NTRS)

    Szewczyk, Nathaniel J.; Conley, Catharine A.

    2003-01-01

    In essence, to survival a spacecraft breakup an animal must not experience a lethal event. Much as with surviving aircraft breakup, dissipation of lethal forces via breakup of the craft around the organism is likely to greatly increase the odds of survival. As spacecraft can travel higher and faster than aircraft, it is often assumed that spacecraft breakup is not a survivable event. Similarly, the belief that aircraft breakup or crashes are not survivable events is still prevalent in the general population. As those of us involved in search and rescue know, it is possible to survive both aircraft breakup and crashes. Here we make the first report of an animal, C. elegans, surviving atmospheric breakup of the spacecraft supporting it and discuss both the lethal events these animals had to escape and the implications implied for search and rescue following spacecraft breakup.

  10. Surfactant-laden drop jellyfish-breakup mode induced by the Marangoni effect

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Zhang, Wen-Bin; Xu, Jian-Liang; Li, Wei-Feng; Liu, Hai-Feng

    2017-03-01

    Drop breakup is a familiar event in both nature and technology. In this study, we find that the bag breakup mode can be replaced by a new breakup mode: jellyfish breakup, when the surfactant concentration of a surfactant-laden drop is high. This new breakup mode has a morphology resembling a jellyfish with many long tentacles. This is due to the inhomogeneous distribution of surfactant in the process of drop deformation and breakup. The thin film of liquid can remain stable as a result of the Marangoni effect. Finally, we propose that the dimensionless surfactant concentration can serve as a criterion for breakup mechanisms.

  11. A patient alignment solution for lung SBRT setups based on a deformable registration technique

    SciTech Connect

    Lu Bo; Mittauer, Kathryn; Li, Jonathan; Samant, Sanjiv; Dagan, Roi; Okunieff, Paul; Kahler, Darren; Liu, Chihray

    2012-12-15

    Purpose: In this work, the authors propose a novel registration strategy for translation-only correction scenarios of lung stereotactic body radiation therapy setups, which can achieve optimal dose coverage for tumors as well as preserve the consistency of registrations with minimal human interference. Methods: The proposed solution (centroid-to-centroidor CTC solution) uses the average four-dimensional CT (A4DCT) as the reference CT. The cone-beam CT (CBCT) is deformed to acquire a new centroid for the internal target volume (ITV) on the CBCT. The registration is then accomplished by simply aligning the centroids of the ITVs between the A4DCT and the CBCT. Sixty-seven cases using 64 patients (each case is associated with separate isocenters) have been investigated with the CTC method and compared with the conventional gray-value (G) mode and bone (B) mode registration methods. Dosimetric effects among the tree methods were demonstrated by 18 selected cases. The uncertainty of the CTC method has also been studied. Results: The registration results demonstrate the superiority of the CTC method over the other two methods. The differences in the D99 and D95 ITV dose coverage between the CTC method and the original plan is small (within 5%) for all of the selected cases except for one for which the tumor presented significant growth during the period between the CT scan and the treatment. Meanwhile, the dose coverage differences between the original plan and the registration results using either the B or G method are significant, as tumor positions varied dramatically, relative to the rib cage, from their positions on the original CT. The largest differences between the D99 and D95 dose coverage of the ITV using the B or G method versus the original plan are as high as 50%. The D20 differences between any of the methods versus the original plan are all less than 2%. Conclusions: The CTC method can generate optimal dose coverage to tumors with much better consistency

  12. Surviving atmospheric spacecraft breakup

    NASA Technical Reports Server (NTRS)

    Szewczyk, Nathaniel J.; McLamb, William

    2005-01-01

    Spacecraft travel higher and faster than aircraft, making breakup potentially less survivable. As with aircraft breakup, the dissipation of lethal forces via spacecraft breakup around an organism is likely to greatly increase the odds of survival. By employing a knowledge of space and aviation physiology, comparative physiology, and search-and-rescue techniques, we were able to correctly predict and execute the recovery of live animals following the breakup of the space shuttle Columbia. In this study, we make what is, to our knowledge, the first report of an animal, Caenorhabditis elegans, surviving the atmospheric breakup of the spacecraft that was supporting it and discuss both the lethal events these animals had to escape and the implications for search and rescue following spacecraft breakup.

  13. Aerodynamic Droplet Breakup.

    DTIC Science & Technology

    1982-05-24

    3 I SURFACE TENSION VARIATIONS ... ........ 9 I VISCOUS EFFECTS ..................... 11 WEBER NUMBER EFFECT .i. . . . . ...... 11 SU MlARY...AVMA X = 100 m/s) ...................... .8 4 SURFACE TENSION EFFECTS ON DROPLET BREAKUP .... ........ 10 5 VISCOSITY EFFECTS ON DROPLET BREAKUP...studied. The primary goal of this initial phase was to examine the effect of liquid properties (viscosity and surface tension ) on the breakup mechanism

  14. Cell-generated traction forces and the resulting matrix deformation modulate microvascular alignment and growth during angiogenesis

    PubMed Central

    Underwood, Clayton J.; Edgar, Lowell T.; Hoying, James B.

    2014-01-01

    The details of the mechanical factors that modulate angiogenesis remain poorly understood. Previous in vitro studies of angiogenesis using microvessel fragments cultured within collagen constructs demonstrated that neovessel alignment can be induced via mechanical constraint of the boundaries (i.e., boundary conditions). The objective of this study was to investigate the role of mechanical boundary conditions in the regulation of angiogenic alignment and growth in an in vitro model of angiogenesis. Angiogenic microvessels within three-dimensional constructs were subjected to different boundary conditions, thus producing different stress and strain fields during growth. Neovessel outgrowth and orientation were quantified from confocal image data after 6 days. Vascularity and branching decreased as the amount of constraint imposed on the culture increased. In long-axis constrained hexahedral constructs, microvessels aligned parallel to the constrained axis. In contrast, constructs that were constrained along the short axis had random microvessel orientation. Finite element models were used to simulate the contraction of gels under the various boundary conditions and to predict the local strain field experienced by microvessels. Results from the experiments and simulations demonstrated that microvessels aligned perpendicular to directions of compressive strain. Alignment was due to anisotropic deformation of the matrix from cell-generated traction forces interacting with the mechanical boundary conditions. These findings demonstrate that boundary conditions and thus the effective stiffness of the matrix regulate angiogenesis. This study offers a potential explanation for the oriented vascular beds that occur in native tissues and provides the basis for improved control of tissue vascularization in both native tissues and tissue-engineered constructs. PMID:24816262

  15. Alignment of sparse freehand 3-D ultrasound with preoperative images of the liver using models of respiratory motion and deformation.

    PubMed

    Blackall, Jane M; Penney, Graeme P; King, Andrew P; Hawkes, David J

    2005-11-01

    We present a method for alignment of an interventional plan to optically tracked two-dimensional intraoperative ultrasound (US) images of the liver. Our clinical motivation is to enable the accurate transfer of information from three-dimensional preoperative imaging modalities [magnetic resonance (MR) or computed tomography (CT)] to intraoperative US to aid needle placement for thermal ablation of liver metastases. An initial rigid registration to intraoperative coordinates is obtained using a set of US images acquired at maximum exhalation. A preprocessing step is applied to both the preoperative images and the US images to produce evidence of corresponding structures. This yields two sets of images representing classification of regions as vessels. The registration then proceeds using these images. The preoperative images and plan are then warped to correspond to a single US slice acquired at an unknown point in the breathing cycle where the liver is likely to have moved and deformed relative to the preoperative image. Alignment is constrained using a patient-specific model of breathing motion and deformation. Target registration error is estimated by carrying out simulation experiments using resliced MR volumes to simulate real US and comparing the registration results to a "bronze-standard" registration performed on the full MR volume. Finally, the system is tested using real US and verified using visual inspection.

  16. Coupling between sagittal and frontal plane deformity correction in idiopathic thoracic scoliosis and its relationship with postoperative sagittal alignment.

    PubMed

    Luk, Keith D K; Vidyadhara, Srinivasa; Lu, D S; Wong, Y W; Cheung, W Y; Cheung, Kenneth M C

    2010-05-15

    Prospective clinical-radiographic study. To investigate the natural coupling behavior between frontal deformity correction and the simultaneous changes in thoracic kyphosis, and to examine how the postoperative thoracic sagittal realignment relates to this natural coupling behavior. Restoration of the sagittal alignment is one of the fundamental goals in scoliosis correction surgery. It is generally achieved by rod precontouring intraoperatively. However, clinical studies suggested that postoperative sagittal realignment seems to be more affected by the inherent properties of the spine rather than the instrumentation or the surgical maneuver. Ninety-eight idiopathic scoliosis patients with thoracic curves treated with one-stage posterior spinal fusion, using corrective segmental spinal instrumentation (hook-rod or pedicle screw-rod constructs) were investigated. Pre- and postoperative frontal and sagittal alignments were measured by standing anteroposterior and lateral radiographs. Preoperative frontal plane flexibility was assessed by the fulcrum bending radiograph in the standard manner, an additional radiograph was taken in the lateral plane, to assess how this frontal correction force affects sagittal plane alignment (lateral fulcrum bending radiograph). When thoracic frontal deformity was corrected under fulcrum bending, coupled changes in the thoracic kyphosis demonstrated 3 different patterns: thoracic kyphosis increased in 25 patients with a mean kyphosis of 9 degrees to 19 degrees, decreased in 45 with a mean of 34 degrees to 21 degrees and remained unchanged (within 3 degrees ) in 28 with a mean of 19 degrees to 18 degrees. After surgery, the direction of correction of thoracic kyphosis significantly correlated with the coupling patterns demonstrated on fulcrum bending radiographs (r = 0.579, P < 0.001). However, the actual postoperative thoracic kyphosis angle cannot be predicted by the preoperative lateral fulcrum bending radiograph. There was no

  17. Catastrophic drop breakup in electric field.

    PubMed

    Raut, Janhavi S; Akella, Sathish; Singh, Amitkumar; Naik, Vijay M

    2009-05-05

    We report novel observations revealing the catastrophic breakup of water drops containing surfactant molecules, which are suspended in oil and subjected to an electric field of strength approximately 10(5) V/m. The observed breakup was distinctly different from the gradual end pinch-off or tip-streaming modes reported earlier in the literature. There was no observable characteristic deformation of the drop prior to breakup. The time scales involved in the breakup and the resultant droplet sizes were much smaller in the phenomenon observed by us. We hypothesize that this mode of drop breakup is obtained by the combined effect of an external electric field that imposes tensile stresses on the surface of the drop, and characteristic stress-strain behavior for tensile deformation exhibited by the liquid drop in the presence of a suitable surfactant, which not only lowers the interfacial tension (and hence the cohesive strength) of the drop but also simultaneously renders the interface nonductile or brittle at high enough concentration. We have identified the relevant thermodynamic parameter, viz., the sum of interfacial tension, sigma, and the Gibbs elasticity, epsilon, which plays a decisive role in determining the mode of drop breakup. The parameter (epsilon + sigma) represents the internal restoration stress of a liquid drop opposing rapid, short-time-scale perturbations or local deformations in the drop shape under the influence of external impulses or stresses. A thermodynamic "state" diagram of (epsilon + sigma) versus interfacial area per surfactant molecule adsorbed at the drop interface shows a "maximum" at a critical transition concentration (ctc). Below this concentration of the surfactant, the drop undergoes tip streaming or pinch off. Above this concentration, the drop may undergo catastrophic disintegration if the external stress is high enough to overcome the ultimate cohesive strength of the drop's interface.

  18. Breakup Characteristics of Nanocylinders

    NASA Astrophysics Data System (ADS)

    Reddy, Harinath; Tiwari, Anupam; Mukhopadhyay, Saumyadip; Abraham, John

    2008-11-01

    Liquid breakup at the macroscale has been studied extensively for over a hundred years, but breakup at the nanoscale has only recently attracted attention. The focus of the present work is on the breakup of liquid nanocylinders. Nanocylinders are encountered in several engineering applications and biological systems, e.g. printing on micro-circuitry, precision manufacturing, Golgi apparatus. Breakup at the nanoscale is primarily through the Rayleigh capillary mechanism since the Reynolds numbers are low. The specific research question we address is: does the breakup-time of liquid cylinders at the nanolevel follow the classical scaling relationships derived for capillary breakup at the macrolevel. A coarse-grained molecular dynamics approach is employed for the studies. We will show that for changes in cylinder radius, the scaling holds; but, when viscosity and surface tension are varied, the scaling does not hold. Possible reasons, attributed primarily to the origin of the instability that leads to the breakup, are discussed. Comparisons of other outcomes at the two levels will also be presented.

  19. [[INFLUENCES OF PREOPERATIVE SEVERE LOWER LIMB DEFORMITY ON PROSTHESIS INSTALLATION AND ALIGNMENT RESTORATION IN TOTAL KNEE ARTHROPLASTY].

    PubMed

    Yu, Baoxi; Fang, Shuying; Fu, Ming; Zhang, Zhiqi; Wu, Peihui; Huang Zhiyu; Sun, Hong

    2016-03-01

    To investigate the effect of preoperative valgus or varus deformity on the prosthesis installation and alignment restoration in total knee arthroplasty (TKA). Between January 2012 and December 2013, 198 patients (245 knees) with osteoarthritis underwent primary TKA, and the clinical data were retrospectively analyzed. There were 23 males and 175 females, with the average age of 67 years (range, 43-90 years). Single knee and double knees were involved in 151 and 47 cases respectively. The disease duration was from 1 month to 30 years (mean, 8.99 years). The anteroposterior X-ray films of whole lower limbs were taken, and the femorotibial angle (FT) was measured before operation and at 1 week after operation; the mechanical femoral angle (MF) and the anatomical tibial angle (AT) at 1 week after operation were measured. The correlation analysis was made for pre- and post-operative FT, MF, and AT. According to the valgus or varus deformity before operation, all patients were divided into 5 groups: ≥ 20 degrees varus (group A), 10-20 degrees varus (group B), ≤ 10 degrees varus (group C), < 10 degrees valgus (group D), and ≥ 10 degrees valgus (group E), and the above indicators were compared between groups. And the rate of the good limb alignment was recorded after operation. The pre- and post-operative FT were (171.53 ± 9.12) and (177.38 ± 3.57)degrees respectively, and postoperative MF and AT were (89.00 ± 2.68) and (88.62 ± 2.16) respectively. Preoperative FT was associated with postoperative FT and MF (r = 0.375, P = 0.000; r = 0.386, P = 0.000), but it was not correlated with AT (r = 0.024, P = 0.710). Postoperative FT was associated with MF and AT (r = 0.707, P = 0.000; r = 0.582, P = 0.000). Postoperative FT was significantly increased when compared with preoperative FT in each group (P < 0.05). There were significant differences in preoperative FT between groups (P < 0.05). There were significant differences in postoperative FT when compared group A

  20. Polyethylene damage and deformation on fixed-bearing, non-conforming unicondylar knee replacements corresponding to progressive changes in alignment and fixation.

    PubMed

    Harman, Melinda K; Schmitt, Sabine; Rössing, Sven; Banks, Scott A; Sharf, Hans-Peter; Viceconti, Marco; Hodge, W Andrew

    2010-07-01

    Deviations from nominal alignment of unicondylar knee replacements impact knee biomechanics, including the load and stress distribution at the articular contact surfaces. This study characterizes relationships between the biomechanical environment, distinguished by progressive changes in alignment and fixation, and articular damage and deformation in a consecutive series of retrieved unicondylar knee replacements. Twenty seven fixed-bearing, non-conforming unicondylar knee replacements of one design were retrieved after 2 to 13 years of in vivo function. The in vivo biomechanical environment was characterized by grading component migration measured from full-length radiographs and grading component fixation based on intraoperative manual palpation. Articular damage patterns and linear deformation on the polyethylene inserts were measured using optical photogrammetry and contact point digitization. Articular damage patterns and surface deformation on the explanted polyethylene inserts corresponded to progressive changes in component alignment and fixation. Component migration produced higher deformation rates, whereas loosening contributed to larger damage areas but lower deformation rates. Migration and loosening of the femoral component, but not the tibial component, were factors contributing to large regions of abrasion concentrated on the articular periphery. Classifying component migration and fixation at revision proved useful for distinguishing common biomechanical conditions associated with the varied polyethylene damage patterns and linear deformation for this fixed-bearing, non-conforming design. Pre-clinical evaluations of unicondylar knee replacements that are capable of reproducing variations in clinical alignment and predicting the observed wear mechanisms are necessary to better understand the impact of knee biomechanics and design on unicondylar knee replacement longevity. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  1. Description of Jet Breakup

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.

    1996-01-01

    In this article we review recent results on the breakup of cylindrical jets of a Newtonian fluid. Capillary forces provide the main driving mechanism and our interest is in the description of the flow as the jet pinches to form drops. The approach is to describe such topological singularities by constructing local (in time and space) similarity solutions from the governing equations. This is described for breakup according to the Euler, Stokes or Navier-Stokes equations. It is found that slender jet theories can be applied when viscosity is present, but for inviscid jets the local shape of the jet at breakup is most likely of a non-slender geometry. Systems of one-dimensional models of the governing equations are solved numerically in order to illustrate these differences.

  2. Droplet breakup dynamics of weakly viscoelastic fluids

    NASA Astrophysics Data System (ADS)

    Marshall, Kristin; Walker, Travis

    2016-11-01

    The addition of macromolecules to solvent, even in dilute quantities, can alter a fluid's response in an extensional flow. For low-viscosity fluids, the presence of elasticity may not be apparent when measured using a standard rotational rheometer, yet it may still alter the response of a fluid when undergoing an extensional deformation, especially at small length scales where elastic effects are enhanced. Applications such as microfluidics necessitate investigating the dynamics of fluids with elastic properties that are not pronounced at large length scales. In the present work, a microfluidic cross-slot configuration is used to study the effects of elasticity on droplet breakup. Droplet breakup and the subsequent iterated-stretching - where beads form along a filament connecting two primary droplets - were observed for a variety of material and flow conditions. We present a relationship on the modes of bead formation and how and when these modes will form based on key parameters such as the properties of the outer continuous-phase fluid. The results are vital not only for simulating the droplet breakup of weakly viscoelastic fluids but also for understanding how the droplet breakup event can be used for characterizing the extensional properties of weakly-viscoelastic fluids.

  3. Selective breakup of lipid vesicles under acoustic microstreaming flow

    NASA Astrophysics Data System (ADS)

    Pommella, Angelo; Garbin, Valeria

    2014-11-01

    The dynamics of lipid vesicles under small deformation in simple shear flow is well characterized: complex behaviors such as tumbling, breathing, and tank-treading are observed depending on the viscosity contrast between inner and outer fluid, vesicle excess area, membrane viscosity, and bending modulus. In contrast, phenomena upon large deformation are still poorly understood, in particular vesicle breakup. Simple shear flow geometries do not allow to reach the large stresses necessary to cause vesicle breakup. We use the acoustic microstreaming flow generated by an oscillating microbubble to study the large deformation and breakup of giant unilamellar vesicles. The deformation is governed by a capillary number based on the membrane elasticity K : Ca = ηγ˙a / K where η is the viscosity of the outer fluid, a the vesicle radius, and γ˙ the shear rate. We explore the effect of the mechanical properties of the membrane, and demonstrated selective breakup of vesicles based on the difference in membrane elasticity. The results reveal the influence of membrane mechanical properties in shear-induced vesicle breakup and the possibility to control in a quantitative way the selectivity of the process, with potential applications in biomedical technologies. The authors acknowledge funding from EU/FP7 Grant Number 618333.

  4. Cervical compensatory alignment changes following correction of adult thoracic deformity: a multicenter experience in 57 patients with a 2-year follow-up.

    PubMed

    Oh, Taemin; Scheer, Justin K; Eastlack, Robert; Smith, Justin S; Lafage, Virginie; Protopsaltis, Themistocles S; Klineberg, Eric; Passias, Peter G; Deviren, Vedat; Hostin, Richard; Gupta, Munish; Bess, Shay; Schwab, Frank; Shaffrey, Christopher I; Ames, Christopher P

    2015-06-01

    OBJECT Alignment changes in the cervical spine that occur following surgical correction for thoracic deformity remain poorly understood. The purpose of this study was to evaluate such changes in a cohort of adults with thoracic deformity treated surgically. METHODS The authors conducted a multicenter retrospective analysis of consecutive patients with thoracic deformity. Inclusion criteria for this study were as follows: corrective osteotomy for thoracic deformity, upper-most instrumented vertebra (UIV) between T-1 and T-4, lower-most instrumented vertebra (LIV) at or above L-5 (LIV ≥ L-5) or at the ilium (LIV-ilium), and a minimum radiographic follow-up of 2 years. Sagittal radiographic parameters were assessed preoperatively as well as at 3 months and 2 years postoperatively, including the C-7 sagittal vertical axis (SVA), C2-7 cervical lordosis (CL), C2-7 SVA, T-1 slope (T1S), T1S minus CL (T1S-CL), T2-12 thoracic kyphosis (TK), apical TK, lumbar lordosis (LL), pelvic incidence (PI), PI-LL, pelvic tilt (PT), and sacral slope (SS). RESULTS Fifty-seven patients with a mean age of 49.1 ± 14.6 years met the study inclusion criteria. The preoperative prevalence of increased CL (CL > 15°) was 48.9%. Both 3-month and 2-year apical TK improved from baseline (p < 0.05, statistically significant). At the 2-year follow-up, only the C2-7 SVA increased significantly from baseline (p = 0.01), whereas LL decreased from baseline (p < 0.01). The prevalence of increased CL was 35.3% at 3 months and 47.8% at 2 years, which did not represent a significant change. Postoperative cervical alignment changes were not significantly different from preoperative values regardless of the LIV (LIV ≥ L-5 or LIV-ilium, p > 0.05 for both). In a subset of patients with a maximum TK ≥ 60° (35 patients) and 3-column osteotomy (38 patients), no significant postoperative cervical changes were seen. CONCLUSION Increased CL is common in adult spinal deformity patients with thoracic deformities

  5. Modified compensation algorithm of lever-arm effect and flexural deformation for polar shipborne transfer alignment based on improved adaptive Kalman filter

    NASA Astrophysics Data System (ADS)

    Wang, Tongda; Cheng, Jianhua; Guan, Dongxue; Kang, Yingyao; Zhang, Wei

    2017-09-01

    Due to the lever-arm effect and flexural deformation in the practical application of transfer alignment (TA), the TA performance is decreased. The existing polar TA algorithm only compensates a fixed lever-arm without considering the dynamic lever-arm caused by flexural deformation; traditional non-polar TA algorithms also have some limitations. Thus, the performance of existing compensation algorithms is unsatisfactory. In this paper, a modified compensation algorithm of the lever-arm effect and flexural deformation is proposed to promote the accuracy and speed of the polar TA. On the basis of a dynamic lever-arm model and a noise compensation method for flexural deformation, polar TA equations are derived in grid frames. Based on the velocity-plus-attitude matching method, the filter models of polar TA are designed. An adaptive Kalman filter (AKF) is improved to promote the robustness and accuracy of the system, and then applied to the estimation of the misalignment angles. Simulation and experiment results have demonstrated that the modified compensation algorithm based on the improved AKF for polar TA can effectively compensate the lever-arm effect and flexural deformation, and then improve the accuracy and speed of TA in the polar region.

  6. Capillary breakup of fluid threads within confinement

    NASA Astrophysics Data System (ADS)

    Hu, Guoqing; Xue, Chundong; Chen, Xiaodong

    2016-11-01

    Fluid thread breakup is a widespread phenomenon in nature, industry, and daily life. Driven by surface tension (or capillarity) at low flow-rate condition, the breakup scenario is usually called capillary instability or Plateau-Rayleigh instability. Fluid thread deforms under confinement of ambient fluid to form a fluid neck. Thinning of the neck at low flow-rate condition is quasistatic until the interface becomes unstable and collapses to breakup. Underlying mechanisms and universalities of both the stable and unstable thinning remain, however, unclear and even contradictory. Here we conduct new numerical and experimental studies to show that confined interfaces are not only stabilized but also destabilized by capillarity at low flow-rate condition. Capillary stabilization is attributed to confinement-determined internal pressure that is higher than capillary pressure along the neck. Two origins of capillary destabilization are identified: one is confinement-induced gradient of capillary pressure along the interface; the other is the competition between local capillary pressure and internal pressure. This work was supported by National Natural Science Foundation of China (Grant No. 11402274, 11272321, and 11572334).

  7. Drop Breakup in Fixed Bed Flows as Model Stochastic Flow Fields

    NASA Technical Reports Server (NTRS)

    Shaqfeh, Eric S. G.; Mosler, Alisa B.; Patel, Prateek

    1999-01-01

    We examine drop breakup in a class of stochastic flow fields as a model for the flow through fixed fiber beds and to elucidate the general mechanisms whereby drops breakup in disordered, Lagrangian unsteady flows. Our study consists of two parallel streams of investigation. First, large scale numerical simulations of drop breakup in a class of anisotropic Gaussian fields will be presented. These fields are generated spectrally and have been shown in a previous publication to be exact representations of the flow in a dilute disordered bed of fibers if close interactions between the fibers and the drops are dynamically unimportant. In these simulations the drop shape is represented by second and third order small deformation theories which have been shown to be excellent for the prediction of drop breakup in steady strong flows. We show via these simulations that the mechanisms of drop breakup in these flows are quite different than in steady flows. The predominant mechanism of breakup appears to be very short lived twist breakups. Moreover, the occurrence of breakup events is poorly predicted by either the strength of the local flow in which the drop finds itself at breakup, or the degree of deformation that the drop achieves prior to breakup. It is suggested that a correlation function of both is necessary to be predictive of breakup events. In the second part of our research experiments are presented where the drop deformation and breakup in PDMS/polyisobutylene emulsions is considered. We consider very dilute emulsions such that coalescence is unimportant. The flows considered are simple shear and the flow through fixed fiber beds. Turbidity, small angle light scattering, dichroism and microscopy are used to interrogate the drop deformation process in both flows. It is demonstrated that breakup at very low capillary numbers occurs in both flows but larger drop deformation occurs in the fixed bed flow. Moreover, it is witnessed that breakup in the bed occurs

  8. Drop breakup in the flow through fixed fiber beds: An experimental and computational investigation

    NASA Astrophysics Data System (ADS)

    Patel, Prateek D.; Shaqfeh, Eric S. G.; Butler, Jason E.; Cristini, Vittorio; Bławzdziewicz, Jerzy; Loewenberg, Michael

    2003-05-01

    Dilute fixed fiber beds provide a model system for studying drop dynamics in disordered flows. Fluctuations about the mean uniform velocity are generated by fiber elements within the media, and the disturbance velocities far from any single fiber (at distances on the order of the pore size) have been predicted to be strong in terms of drop deformation and breakup by Mosler and Shaqfeh [Phys. Fluids 9, 5 (1997)]. In this work, we focus on the importance of near-field interactions, or the flow close to individual fibers. We present experimental observations of drop deformation and breakup during flow through a dilute bed of randomly placed fibers. We found breakup to result from only close interactions with fibers and describe two near-field breakup mechanisms which we term "graze" and "hairpin" processes. In addition, we present the breakup probability through the experimental fiber bed as a function of the appropriate Capillary number Ca. To better understand the near-field interactions, we used the boundary integral method to determine drop shape evolution in the flow around an infinite fiber within a porous medium, and our simulations capture the breakup mechanisms observed during experiments. To compare with experimental breakup probabilities, we have defined a critical offset for breakup during flow past a fiber and assuming straight center-of-mass trajectories, calculated breakup probabilities based on this simple model. These predictions compare well with the experimental measurements for Ca⩾2.

  9. How the neck affects the back: changes in regional cervical sagittal alignment correlate to HRQOL improvement in adult thoracolumbar deformity patients at 2-year follow-up.

    PubMed

    Protopsaltis, Themistocles S; Scheer, Justin K; Terran, Jamie S; Smith, Justin S; Hamilton, D Kojo; Kim, Han Jo; Mundis, Greg M; Hart, Robert A; McCarthy, Ian M; Klineberg, Eric; Lafage, Virginie; Bess, Shay; Schwab, Frank; Shaffrey, Christopher I; Ames, Christopher P

    2015-08-01

    OBJECT Regional cervical sagittal alignment (C2-7 sagittal vertical axis [SVA]) has been shown to correlate with health-related quality of life (HRQOL). The study objective was to examine the relationship between cervical and thoracolumbar alignment parameters with HRQOL among patients with operative and nonoperative adult thoracolumbar deformity. METHODS This is a multicenter prospective data collection of consecutive patients with adult thoracolumbar spinal deformity. Clinical measures of disability included the Oswestry Disability Index (ODI), Scoliosis Research Society-22 Patient Questionnaire (SRS-22), and 36-Item Short-Form Health Survey (SF-36). Cervical radiographic parameters were correlated with global sagittal parameters within the nonoperative and operative cohorts. A partial correlation analysis was performed controlling for C-7 SVA. The operative group was subanalyzed by the magnitude of global deformity (C-7 SVA ≥ 5 cm vs < 5 cm). RESULTS A total of 318 patients were included (186 operative and 132 nonoperative). The mean age was 55.4 ± 14.9 years. Operative patients had significantly worse baseline HRQOL and significantly larger C-7 SVA, pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C2-7 SVA. The operative patients with baseline C-7 SVA ≥ 5 cm had significantly larger C2-7 lordosis (CL), C2-7 SVA, C-7 SVA, PI-LL, and PT than patients with a normal C-7 SVA. For all patients, baseline C2-7 SVA and CL significantly correlated with baseline ODI, Physical Component Summary (PCS), SRS Activity domain, and SRS Appearance domain. Baseline C2-7 SVA also correlated with SRS Pain and SRS Total. For the operative patients with baseline C-7 SVA ≥ 5 cm, the 2-year C2-7 SVA significantly correlated with 2-year Mental Component Summary, SRS Mental, SRS Satisfaction, and decreases in ODI. Decreases in C2-7 SVA at 2 years significantly correlated with lower ODI at 2 years. Using partial correlations while controlling for

  10. Importance of Radiological Evaluation of Global Spinal Balance Together with Lower Limb Alignment in Planning Lumbar Spine Deformity Surgery - Illustrative Case Presentation.

    PubMed

    Głowacki, Mariusz; Walecki, Jerzy; Kołakowski, Przemysław; Kolońska, Danuta

    2017-01-01

    The presented case illustrates the critical role of a detailed preoperative radiological evaluation in complex spine surgery. A 49-year-old patient was admitted for a revision surgery after L3-L5 fusion. Preoperative assessment showed preserved sagittal balance, coronal imbalance and valgus knee deformity. The patient reported pain of 8-10 in VAS (Visual Analogue Scale) and had an ODI (Oswestry Disability Index) of 60%. The first step of the surgery was L2-S1 fusion with decompression and spine deformity correction. The second step involved anti-valgus osteotomy of the right tibial bone. The assessment of global spinal balance together with lower extremity alignment should be strongly recommended.

  11. Quantitative analysis of tissue deformation dynamics reveals three characteristic growth modes and globally aligned anisotropic tissue deformation during chick limb development.

    PubMed

    Morishita, Yoshihiro; Kuroiwa, Atsushi; Suzuki, Takayuki

    2015-05-01

    Tissue-level characterization of deformation dynamics is crucial for understanding organ morphogenetic mechanisms, especially the interhierarchical links among molecular activities, cellular behaviors and tissue/organ morphogenetic processes. Limb development is a well-studied topic in vertebrate organogenesis. Nevertheless, there is still little understanding of tissue-level deformation relative to molecular and cellular dynamics. This is mainly because live recording of detailed cell behaviors in whole tissues is technically difficult. To overcome this limitation, by applying a recently developed Bayesian approach, we here constructed tissue deformation maps for chick limb development with high precision, based on snapshot lineage tracing using dye injection. The precision of the constructed maps was validated with a clear statistical criterion. From the geometrical analysis of the map, we identified three characteristic tissue growth modes in the limb and showed that they are consistent with local growth factor activity and cell cycle length. In particular, we report that SHH signaling activity changes dynamically with developmental stage and strongly correlates with the dynamic shift in the tissue growth mode. We also found anisotropic tissue deformation along the proximal-distal axis. Morphogenetic simulation and experimental studies suggested that this directional tissue elongation, and not local growth, has the greatest impact on limb shaping. This result was supported by the novel finding that anisotropic tissue elongation along the proximal-distal axis occurs independently of cell proliferation. Our study marks a pivotal point for multi-scale system understanding in vertebrate development. © 2015. Published by The Company of Biologists Ltd.

  12. On the breakup of tectonic plates by polar wandering

    NASA Technical Reports Server (NTRS)

    Liu, H.-S.

    1974-01-01

    The equations for the stresses in a homogeneous shell of uniform thickness caused by a shift of the axis of rotation are derived. The magnitude of these stresses reaches a maximum value of the order of 10 to the 9th power dyn/sq cm, which is sufficient for explaining a tectonic breakup. In order to deduce the fracture pattern according to which the breakup of tectonic plates can be expected the theory of plastic deformation of shells is applied. The analysis of this pattern gives an explanation of the existing boundary systems of the major tectonic plates as described by Morgan (1968), LePichon (1968) and Isacks et al. (1968).

  13. Elastic Coulomb breakup of 34Na

    NASA Astrophysics Data System (ADS)

    Singh, G.; Shubhchintak, Chatterjee, R.

    2016-08-01

    Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

  14. Three-column osteotomy for correction of cervical and cervicothoracic deformities: alignment changes and early complications in a multicenter prospective series of 23 patients.

    PubMed

    Smith, Justin S; Shaffrey, Christopher I; Lafage, Renaud; Lafage, Virginie; Schwab, Frank J; Kim, Han Jo; Scheer, Justin K; Protopsaltis, Themistocles; Passias, Peter; Mundis, Gregory; Hart, Robert; Neuman, Brian; Klineberg, Eric; Hostin, Richard; Bess, Shay; Deviren, Vedat; Ames, Christopher P

    2017-08-01

    Three-column osteotomy (3CO), including pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR), can provide powerful alignment correction for adult cervical deformity (ACD). Our objective was to assess alignment changes and early complications associated with 3CO for ACD. ACD patients treated with 3CO with minimum 90-day follow-up were identified from a prospectively collected multicenter ACD database. Complications within 90-days of surgery and pre- and postoperative radiographs were collected. All 23 ACD patients treated with 3CO (14 PSO/9 VCR) had minimum 90-day follow-up (mean age 62.3 years, previous cervical/cervicothoracic instrumentation in 52.2% and thoracic/thoracolumbar instrumentation in 47.8%). The primary diagnosis was kyphosis in 91.3% and coronal deformity in 8.7%. The mean number of fusion levels was 12 (range 6-18). The most common 3CO levels were T1 (39.1%), T2 (30.4%) and T3 (21.7%). Eighteen (12 major/6 minor) complications affected 13 (56.5%) patients. The most common complications were neurologic deficit (17.4%), wound infection (8.7%), distal junctional kyphosis (DJK 8.7%), and cardiorespiratory failure (8.7%). Three (13.0%) patients required re-operation within 90-days (1 each for nerve root motor deficit, DJK, and implant pain/prominence). Cervical alignment improved significantly following 3CO, including cervical lordosis (-2.8° to -12.9°, p = 0.036), C2-7 sagittal vertical axis (64.6-42.3 mm, p < 0.001), and T1 slope minus cervical lordosis (46.4°-27.0°, p < 0.001). Among 23 ACD patients treated with 3CO, cervical alignment improved significantly following surgery. Thirteen (56.5%) patients had at least one complication. The most common complications were neurologic deficit, infection, DJK, and cardiorespiratory failure.

  15. Breakup modes of fluid drops in confined shear flows

    NASA Astrophysics Data System (ADS)

    Barai, Nilkamal; Mandal, Nibir

    2016-07-01

    Using a conservative level set method we investigate the deformation behavior of isolated spherical fluid drops in a fluid channel subjected to simple shear flows, accounting the following three non-dimensional parameters: (1) degree of confinement (Wc = 2a/h, where a is the drop radius and h is the channel thickness); (2) viscosity ratio between the two fluids (λ = μd/μm, where μd is the drop viscosity and μm is the matrix viscosity); and (3) capillary number (Ca). For a given Wc, a drop steadily deforms to attain a stable geometry (Taylor number and inclination of its long axis to the shear direction) when Ca < 0.3. For Ca > 0.3, the deformation behavior turns to be unsteady, leading to oscillatory variations of both its shape and orientation with progressive shear. This kind of unsteady deformation also occurs in a condition of high viscosity ratios (λ > 2). Here we present a detailed parametric analysis of the drop geometry with increasing shear as a function of Wc, Ca, and λ. Under a threshold condition, deforming drops become unstable, resulting in their breakup into smaller droplets. We recognize three principal modes of breakup: Mode I (mid-point pinching), Mode II (edge breakup), and Mode III (homogeneous breakup). Each of these modes is shown to be most effective in the specific field defined by Ca and λ. Our study also demonstrates the role of channel confinement (Wc) in controlling the transition of Mode I to III. Finally, we discuss implications of the three modes in determining characteristic drop size distributions in multiphase flows.

  16. Multivariate analysis of factors associated with kyphotic deformity after laminoplasty in cervical spondylotic myelopathy patients without preoperative kyphotic alignment

    PubMed Central

    Cao, JunMing; Zhang, JingTao; Yang, DaLong; Yang, Liu; Shen, Yong

    2017-01-01

    The risk factors of post-laminoplasty kyphosis in patients with cervical spondylotic myelopathy (CSM) without preoperative kyphotic alignment are not well known. This study aimed to compare clinical and radiological data between patients with or without post-laminoplasty kyphosis and to investigate the factors associated with post-laminoplasty kyphosis in CSM patients without preoperative kyphotic alignment. Patients (n = 194) who received unilateral expansive open-door cervical laminoplasty with miniplate fixation and completed a 1-year follow-up were enrolled. Patients were grouped according to whether they suffered from postoperative kyphosis (P) or not (NP). Postoperative kyphosis was observed in 21 (10.8%) patients. The recovery rates of the Japanese Orthopaedic Association scores at the 1-year follow-up in the P group were inferior to those in the NP group (31.9% vs. 65.2%, P < 0.001). Logistic regression with post-laminoplasty kyphosis as the dependent variable showed independent risks associated with an increased C2–7 sagittal vertical axis (SVA, odds ratio [OR] = 1.085, 95% confidence interval [CI] = 1.025–1.203, P = 0.015), destroyed facet joints (OR = 1.132, 95% CI = 1.068–1.208, P < 0.001), and cephalad vertebral level undergoing laminoplasty (CVLL, OR = 2.860, 95% CI = 1.164–6.847, P = 0.021). These findings suggest that CVLL, C2–7 SVA, and destroyed facet joints are associated with kyphosis after laminoplasty in CSM patients without preoperative kyphotic alignment. PMID:28240309

  17. Fault linkage and continental breakup

    NASA Astrophysics Data System (ADS)

    Cresswell, Derren; Lymer, Gaël; Reston, Tim; Stevenson, Carl; Bull, Jonathan; Sawyer, Dale; Morgan, Julia

    2017-04-01

    The magma-poor rifted margin off the west coast of Galicia (NW Spain) has provided some of the key observations in the development of models describing the final stages of rifting and continental breakup. In 2013, we collected a 68 x 20 km 3D seismic survey across the Galicia margin, NE Atlantic. Processing through to 3D Pre-stack Time Migration (12.5 m bin-size) and 3D depth conversion reveals the key structures, including an underlying detachment fault (the S detachment), and the intra-block and inter-block faults. These data reveal multiple phases of faulting, which overlap spatially and temporally, have thinned the crust to between zero and a few km thickness, producing 'basement windows' where crustal basement has been completely pulled apart and sediments lie directly on the mantle. Two approximately N-S trending fault systems are observed: 1) a margin proximal system of two linked faults that are the upward extension (breakaway faults) of the S; in the south they form one surface that splays northward to form two faults with an intervening fault block. These faults were thus demonstrably active at one time rather than sequentially. 2) An oceanward relay structure that shows clear along strike linkage. Faults within the relay trend NE-SW and heavily dissect the basement. The main block bounding faults can be traced from the S detachment through the basement into, and heavily deforming, the syn-rift sediments where they die out, suggesting that the faults propagated up from the S detachment surface. Analysis of the fault heaves and associated maps at different structural levels show complementary fault systems. The pattern of faulting suggests a variation in main tectonic transport direction moving oceanward. This might be interpreted as a temporal change during sequential faulting, however the transfer of extension between faults and the lateral variability of fault blocks suggests that many of the faults across the 3D volume were active at least in part

  18. Inclusive breakup of Borromean nuclei

    NASA Astrophysics Data System (ADS)

    Hussein, M. S.; Carlson, B. V.; Frederico, T.

    2017-06-01

    We derive the inclusive breakup cross section of a three-fragment projectile nuclei, a = b + x 1 +x 2, in the spectator model. The resulting four-body cross section for observing b, is composed of the elastic breakup cross section which contains information about the correlation between the two participant fragments, and the inclusive non-elastic breakup cross section. This latter cross section is found to be a non-trivial four-body generalization of the Austern formula [1], which is proportional to a matrix element of the form, . The new feature here is the three-body absorption, represented by the imaginary potential, W 3b . We analyze this type of absorption and supply ideas of how to calculate its contribution.

  19. Acoustic Emission Analysis of Damage during Compressive Deformation of Amorphous Zr-Based Foams with Aligned, Elongated Pores

    NASA Astrophysics Data System (ADS)

    Cox, Marie E.; Dunand, David C.

    2013-07-01

    Acoustic emission methods are used to investigate the evolution of internal microfractural damage during uniaxial compression of amorphous Zr-based foams with aligned, elongated pores. The foams are fabricated by means of densifying a blend of crystalline W powders and amorphous Zr-based powders with two oxygen contents (0.078 and 0.144 wt pct) by warm equal channel angular extrusion, followed by dissolution of the elongated W phase from the fully densified amorphous matrix. For the high-oxygen foams, prior powder boundaries in the amorphous struts promote damage that accumulates during compression, resulting in energy-absorbing properties comparable with the low-oxygen foams without stress-concentrating powder boundaries. The influence of pore orientation on the evolution of microfracture damage and the ability of the foams to accumulate damage without catastrophic failure is also investigated: pores oriented from 24 to 68 deg to the loading direction promote wall bending, resulting in foams with more diffuse damage and better energy-absorbing properties.

  20. Global analysis of sagittal spinal alignment in major deformities: correlation between lack of lumbar lordosis and flexion of the knee.

    PubMed

    Obeid, Ibrahim; Hauger, Olivier; Aunoble, Stéphane; Bourghli, Anouar; Pellet, Nicolas; Vital, Jean-Marc

    2011-09-01

    It has become well recognised that sagittal balance of the spine is the result of an interaction between the spine and the pelvis. Knee flexion is considered to be the last compensatory mechanism in case of sagittal imbalance, but only few studies have insisted on the relationship between spino-pelvic parameters and lower extremity parameters. Correlation between the lack of lumbar lordosis and knee flexion has not yet been established. A retrospective study was carried out on 28 patients with major spinal deformities. The EOS system was used to measure spinal and pelvic parameters and the knee flexion angle; the lack of lumbar lordosis was calculated after prediction of lumbar lordosis with two different formulas. Correlation analysis between the different measured parameters was performed. Lumbar lordosis correlated with sacral slope (r = -0.71) and moderately with knee flexion angle (r = 0.42). Pelvic tilt correlated moderately with knee flexion angle (r = 0.55). Lack of lumbar lordosis correlated best with knee flexion angle (r = 0.72 and r = 0.63 using the two formulas, respectively). Knee flexion as a compensatory mechanism to sagittal imbalance was well correlated to the lack of lordosis and, depending on the importance of the former parameter, the best procedure to correct sagittal imbalance could be chosen.

  1. Fusion and Breakup of Weakly Bound Nuclei

    SciTech Connect

    Gomes, P. R. S.; Lubian, J.; Padron, I.; Crema, E.; Chamon, L. C.; Hussein, M. S.; Canto, L. F.

    2006-08-14

    We discuss the influence of the breakup process of weakly bound nuclei on the fusion cross section. The complete fusion for heavy targets is found to be suppressed due to the incomplete fusion following the breakup, whereas this effect is negligible for light targets. The total fusion cross sections for stable projectiles are not affected by the breakup process, whereas it is suppressed for halo projectiles. The non capture breakup is the dominant process at sub-barrier energies.

  2. Recent developments in Coulomb breakup calculations

    SciTech Connect

    Capel, P.

    2008-05-12

    The theory of reactions applied to Coulomb breakup of loosely-bound projectiles is reviewed. Both the Continuum Discretized Coupled Channel (CDCC) and time-dependent models are described. Recent results about sensitivity of breakup calculations to the projectile wave function are reviewed. Analyses of the extraction of radiative-capture cross section from Coulomb breakup measurements are presented. Current developments in breakup theory are also mentioned.

  3. Correction of static axial alignment in children with knee varus or valgus deformities through guided growth: Does it also correct dynamic frontal plane moments during walking?

    PubMed

    Böhm, Harald; Stief, Felix; Sander, Klaus; Hösl, Matthias; Döderlein, Leonhard

    2015-09-01

    Malaligned knees are predisposed to the development and progression of unicompartmental degenerations because of the excessive load placed on one side of the knee. Therefore, guided growth in skeletally immature patients is recommended. Indication for correction of varus/valgus deformities are based on static weight bearing radiographs. However, the dynamic knee abduction moment during walking showed only a weak correlation to malalignment determined by static radiographs. Therefore, the aim of the study was to measure the effects of guided growth on the normalization of frontal plane knee joint moments during walking. 15 legs of 8 patients (11-15 years) with idiopathic axial varus or valgus malalignment were analyzed. 16 typically developed peers served as controls. Instrumented gait analysis and clinical assessment were performed the day before implantation and explantation of eight-plates. Correlation between static mechanical tibiofemoral axis angle (MAA) and dynamic frontal plane knee joint moments and their change by guided growth were performed. The changes in dynamic knee moment in the frontal plane following guided growth showed high and significant correlation to the changes in static MAA (R=0.97, p<0.001). Contrary to the correlation of the changes, there was no correlation between static and dynamic measures in both sessions. In consequence two patients that had a natural knee moment before treatment showed a more pathological one after treatment. In conclusion, the changes in the dynamic load situation during walking can be predicted from the changes in static alignment. If pre-surgical gait analysis reveals a natural load situation, despite a static varus or valgus deformity, the intervention must be critically discussed.

  4. Mechanism of Water Droplet Breakup Near the Leading Edge of an Airfoil

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida, Garcia

    2012-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 microns, and airfoil velocities of 70 and 90 m/sec.

  5. Mechanism of Water Droplet Breakup near the Leading Edge of an Airfoil

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida Garcia

    2012-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de T cnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 micrometers, and airfoil velocities of 70 and 90 meters/second.

  6. Shear-Induced Breakup of Cellulose Nanocrystal Aggregates.

    PubMed

    Xu, Hua-Neng; Tang, Yi-You; Ouyang, Xiao-Kun

    2017-01-10

    The flow properties of two kinds of cellulose nanocrystal (CNC) rods with different aspect ratios and similar zeta potentials in aqueous suspensions have been investigated. The aqueous CNC suspensions undergo a direct transition from dilute solution to colloidal glass instead of phase separation with the increasing CNC concentration. The viscosity profile shows a single shear-thinning behavior over the whole range of shear rates investigated. The shear-thinning behavior becomes stronger with the increasing CNC concentration. The viscosity is much higher for the unsonicated suspension when compared with the sonicated suspensions. The CNC rods appear arrested without alignment with an increasing shear rate from the small-angle light scattering patterns. The arrested glass state results from electric double layers surrounding the CNC rods, which give rise to long-ranged repulsive interactions. For the first time, we demonstrate that, within a narrow range of CNC concentrations, a shear-induced breakup process of the CNC aggregates exists when the shear rate is over a critical value and that the process is reversible in the sense that the aggregates can be reformed. We discuss the competition between the shear-induced breakup and the concentration-driven aggregation based on the experimental observations. The generated aggregate structure during the breakup process is characterized by a fractal dimension of 2.41. Furthermore, we determine two important variables-the breakup rate and the characteristic aggregate size-and derive analytical expressions for their evolution during the breakup process. The model predictions are in quantitative agreement with the experimental results.

  7. Droplet Breakup Mechanisms in Air-blast Atomizers

    NASA Astrophysics Data System (ADS)

    Aliabadi, Amir Abbas; Taghavi, Seyed Mohammad; Lim, Kelly

    2011-11-01

    Atomization processes are encountered in many natural and man-made phenomena. Examples are pollen release by plants, human cough or sneeze, engine fuel injectors, spray paint and many more. The physics governing the atomization of liquids is important in understanding and utilizing atomization processes in both natural and industrial processes. We have observed the governing physics of droplet breakup in an air-blast water atomizer using a high magnification, high speed, and high resolution LASER imaging technique. The droplet breakup mechanisms are investigated in three major categories. First, the liquid drops are flattened to form an oblate ellipsoid (lenticular deformation). Subsequent deformation depends on the magnitude of the internal forces relative to external forces. The ellipsoid is converted into a torus that becomes stretched and disintegrates into smaller drops. Second, the drops become elongated to form a long cylindrical thread or ligament that break up into smaller drops (Cigar-shaped deformation). Third, local deformation on the drop surface creates bulges and protuberances that eventually detach themselves from the parent drop to form smaller drops.

  8. Anatomy of an Asteroid Breakup

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-05-01

    A team of scientists has observed the breakup of an asteroid as it orbits the Sun. In a new study, they reveal what theyve learned from their ground- and space-based observations of this disintegration.These Hubble images show the fragments of R3 in higher resolution over the span of October 2013 to February 2014. [Jewitt et al. 2017]Observations of DisintegrationActive asteroids are objects that move on asteroid-like orbits while displaying comet-like behavior. The cause of their activity can vary ranging from outgassing as the asteroid heats up in its solar approach, to expelled debris from a collision, to the entire asteroid flying apart because its spinning too fast.Led by David Jewitt (University of California at Los Angeles), a team of scientists has analyzed observations of the disintegrating asteroid P/2013 R3. The observations span two years and were made by a number of telescopes, including Hubble, Keck (in Hawaii), Magellan (in Chile), and the Very Large Telescope (in Chile).A schematic diagram of the different fragments of R3 and how they relate to each other. Black numbers estimate the fragment separation velocities; red numbers estimate the separation date. [Jewitt et al. 2017]Jewitt and collaborators then used these observations and a bit of modeling to understand what asteroid R3 was like originally, what its pieces are doing now, and what caused it to break up.Cause of the BreakupThe team found that P/2013 R3 broke up into at least 13 pieces, the biggest of which was likely no more than 100-200 meters in size. The original asteroid was probably less than 400 m in radius.By measuring the velocities of the fragments in the various observations, Jewitt and collaborators were able to work backward to determine when each piece broke off. They found that the fragmentation process was spread out over the span of roughly 5 months suggesting that the asteroids breakup wasnt impact-related (otherwise the fragmentation would likely have been all at once

  9. Simulation of lipid vesicle breakup in extensional flows*

    NASA Astrophysics Data System (ADS)

    Banton, Rohan; Eggleton, Charles

    2001-11-01

    Lipid molecules in solution can spontaneously form vesicles encapsulating the solvent. Vesicles can be used to manufacture artificial cells and as a novel means of drug delivery. Unlike biological cells, vesicles do not possess a cytoskeleton (scaffolding for structural rigidity) and cannot resist in-plane shearing forces. The Evans-Skalak strain energy function is used to model the interfacial stresses in the vesicles due to deformation using measured values of the area dilatational and bending moduli. An understanding of vesicle breakup in fluid flow is required in order to effectively design vesicles for particular applications. The Boundary Integral Method is employed to simulate the deformation of the model membrane in both uniaxial and bi-axial extensional flows. The flow field is characterized by a capillary number based on the area dilatational modulus of the vesicle. The response of an initially spherical vesicle to the external flow field was simulated for internal to external viscosity ratios of 0.1,1,10 and capillary numbers in the approximate range of 0.005-0.025. The perturbation analysis developed by Barthes-Biesel (1980) was adapted to predict the deformation of lipid vesicles and compared to the simulations at small capillary numbers. At large capillary numbers, the break-up of the vesicle is simulated and the critical capillary number is determined.

  10. Revised Capillary Breakup Rheometer Method

    NASA Astrophysics Data System (ADS)

    Lu, Louise; Schultz, William; Solomon, Michael

    2014-11-01

    Rather than integrate the one-dimensional equation of motion for a capillary breakup rheometer, we take the axial derivative of that equation. This avoids the determination of the axial force with all of its complications and correction factors. The resulting evolutionary equation that involves either two or four derivatives of the capillary radius as a function of the axial coordinate determines the ratio of elongational viscosity to surface tension coefficient. We examine several silicone and olive oils to show the accuracy of the method for Newtonian fluids. We will discuss our surface tension measurement techniques and briefly describe measurements of viscoelastic materials, including saliva.

  11. Breakup Densities of Hot Nuclei

    NASA Astrophysics Data System (ADS)

    Viola, V. E.; Kwiatkowski, K.; Natowitz, J. B.; Yennello, S. J.

    2004-09-01

    Breakup densities of hot 197Au-like residues have been deduced from the systematic trends of Coulomb parameters required to fit intermediate-mass-fragment kinetic-energy spectra. The results indicate emission from nuclei near normal nuclear density below an excitation energy E*/A≲2 MeV, followed by a gradual decrease to a near-constant value of ρ/ρ0˜0.3 for E*/A≳5 MeV. Temperatures derived from these data with a density-dependent Fermi-gas model yield a nuclear caloric curve that is generally consistent with those derived from isotope ratios.

  12. Capillary breakup of armored liquid filaments

    NASA Astrophysics Data System (ADS)

    Zou, Jun; Lin, Fangye; Ji, Chen

    2017-06-01

    An armored liquid filament is a liquid column wherein particles reside on the liquid-air interface rather than in the bulk of the filament, as is true of a suspension filament. Herein, the capillary breakup of armored liquid filaments is studied using a high-speed camera, where the thinning process can be divided into three stages: the armored liquid stage, the transition stage, and the liquid stage. At the armored liquid stage, the thinning is approximately uniform along the filament. In the transition stage, local deformation occurs and thinning is accelerated owing to the large curvature along the filament. Finally, at the liquid stage, the thinning behavior is similar to that of particle-free filaments. The main focus in the present work is on the armored liquid stage, wherein the volume density of particles in the liquid filament remains nearly constant. In addition, the relative distances between particles in the axial direction on the filament do not change at this stage. By defining an effective surface tension γeff, a model is established to estimate the neck thinning process at this stage.

  13. Simulation of Motion, Heating, and Breakup of Molten Metal Droplets in the Plasma Jet at Plasma-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.; Ryabovolyk, Y. V.; Demyanov, O. I.

    2015-04-01

    The mathematical model for the process of plasma-arc wire spraying is proposed, which describes behavior of molten metal droplets in the plasma jet, allowing for the processes of their deformation and gas-dynamic breakup. Numerical analysis of the processes of motion, heating, and breakup of molten metal droplets, detached from the sprayed wire at plasma-arc spraying of coatings, was performed. It is shown that during molten droplets movement in the plasma jet their multiple breakup takes place, leading to formation of sprayed particles with dimensions much smaller than dimensions of initial droplets, detached from the sprayed wire tip.

  14. Breakup of diminutive Rayleigh jets

    NASA Astrophysics Data System (ADS)

    van Hoeve, Wim; Gekle, Stephan; Snoeijer, Jacco H.; Versluis, Michel; Brenner, Michael P.; Lohse, Detlef

    2010-12-01

    Discharging a liquid from a nozzle at sufficient large velocity leads to a continuous jet that due to capillary forces breaks up into droplets. Here we investigate the formation of microdroplets from the breakup of micron-sized jets with ultra high-speed imaging. The diminutive size of the jet implies a fast breakup time scale τc=√ρr3/γ of the order of 100 ns, and requires imaging at 14×106 frames/s. We directly compare these experiments with a numerical lubrication approximation model that incorporates inertia, surface tension, and viscosity [J. Eggers and T. F. Dupont, J. Fluid Mech. 262, 205 (1994); X. D. Shi, M. P. Brenner, and S. R. Nagel, Science 265, 219 (1994)]. The lubrication model allows to efficiently explore the parameter space to investigate the effect of jet velocity and liquid viscosity on the formation of satellite droplets. In the phase diagram, we identify regions where the formation of satellite droplets is suppressed. We compare the shape of the droplet at pinch-off between the lubrication approximation model and a boundary-integral calculation, showing deviations at the final moment of the pinch-off. In spite of this discrepancy, the results on pinch-off times and droplet and satellite droplet velocity obtained from the lubrication approximation agree with the high-speed imaging results.

  15. Antimisting fuel breakup and flammability

    NASA Technical Reports Server (NTRS)

    Parikh, P.; Fleeter, R.; Sarohia, V.

    1983-01-01

    The breakup behavior and flammability of antimisting turbine fuels subjected to aerodynamic shear are investigated. Fuels tested were Jet A containing 0.3% FM-9 polymer at various levels of degradation ranging from virgin AMK to neat Jet A. The misting behavior of the fuels was quantified by droplet size distribution measurements. A technique based on high resolution laser photography and digital image processing of photographic records for rapid determination of droplet size distribution was developed. The flammability of flowing droplet-air mixtures was quantified by direct measurements of temperature rise in a flame established in the wake of a continuous ignition source. The temperature rise measurements were correlated with droplet size measurements. The flame anchoring phenomenon associated with the breakup of a liquid fuel in the wake of bluff body was shown to be important in the context of a survivable crash scenario. A pass/fail criterion for flammability testing of antimisting fuels, based on this flame-anchoring phenomenon, was proposed. The role of various ignition sources and their intensity in ignition and post-ignition behavior of antimisting fuels was also investigated.

  16. Exclusive breakup measurements for {sup 9}Be

    SciTech Connect

    Fulton, B.R.; Cowin, R.L.; Woolliscroft, R.J.; Clarke, N.M.; Donadille, L.; Freer, M.; Leask, P.J.; Singer, S.M.; Nicoli, M.P.; Benoit, B.; Hanappe, F.; Ninane, A.; Orr, N.A.; Tillier, J.; Stuttge, L.

    2004-10-01

    The first exclusive breakup measurements for the nucleus {sup 9}Be are presented. Breakup via several discrete states is observed following scattering off {sup 12}C and {sup 208}Pb. The results support the prediction of a recent microscopic cluster calculation for a strong n+{sup 8}Be(2{sup +}) state component in the second excited state.

  17. Observations of auroral fading before breakup

    NASA Technical Reports Server (NTRS)

    Pellinen, R. J.; Heikkila, W. J.

    1978-01-01

    The onset of auroral breakup was studied by using a variety of instruments with time resolution of some tens of second. Rapid sequences of all-sky photographs, and fast meridian scans by photometers, show that breakup is usually preceded by moderate brightening, followed by fading of the auroral brightness lasting one or two minutes, before the actual breakup itself. This optical activity is closely correlated with the development of auroral radar echoes. Data from a magnetometer network provide some indication of a correlated response by the local auroral and ionospheric currents. Riometer recordings show a slow decrease in ionspheric radio wave absorption over a period of about ten minutes prior to breakup, with the largest decrease essentially to quiet-time values in the region of auroral fading and subsequent breakup.

  18. Droplet Breakup in Expansion-contraction Microchannels

    PubMed Central

    Zhu, Pingan; Kong, Tiantian; Lei, Leyan; Tian, Xiaowei; Kang, Zhanxiao; Wang, Liqiu

    2016-01-01

    We investigate the influences of expansion-contraction microchannels on droplet breakup in capillary microfluidic devices. With variations in channel dimension, local shear stresses at the injection nozzle and focusing orifice vary, significantly impacting flow behavior including droplet breakup locations and breakup modes. We observe transition of droplet breakup location from focusing orifice to injection nozzle, and three distinct types of recently-reported tip-multi-breaking modes. By balancing local shear stresses and interfacial tension effects, we determine the critical condition for breakup location transition, and characterize the tip-multi-breaking mode quantitatively. In addition, we identify the mechanism responsible for the periodic oscillation of inner fluid tip in tip-multi-breaking mode. Our results offer fundamental understanding of two-phase flow behaviors in expansion-contraction microstructures, and would benefit droplet generation, manipulation and design of microfluidic devices. PMID:26899018

  19. Droplet Breakup in Expansion-contraction Microchannels

    NASA Astrophysics Data System (ADS)

    Zhu, Pingan; Kong, Tiantian; Lei, Leyan; Tian, Xiaowei; Kang, Zhanxiao; Wang, Liqiu

    2016-02-01

    We investigate the influences of expansion-contraction microchannels on droplet breakup in capillary microfluidic devices. With variations in channel dimension, local shear stresses at the injection nozzle and focusing orifice vary, significantly impacting flow behavior including droplet breakup locations and breakup modes. We observe transition of droplet breakup location from focusing orifice to injection nozzle, and three distinct types of recently-reported tip-multi-breaking modes. By balancing local shear stresses and interfacial tension effects, we determine the critical condition for breakup location transition, and characterize the tip-multi-breaking mode quantitatively. In addition, we identify the mechanism responsible for the periodic oscillation of inner fluid tip in tip-multi-breaking mode. Our results offer fundamental understanding of two-phase flow behaviors in expansion-contraction microstructures, and would benefit droplet generation, manipulation and design of microfluidic devices.

  20. Bag breakup of low viscosity drops in the presence of a continuous air jet

    NASA Astrophysics Data System (ADS)

    Kulkarni, V.; Sojka, P. E.

    2014-07-01

    This work examines the breakup of a single drop of various low viscosity fluids as it deforms in the presence of continuous horizontal air jet. Such a fragmentation typically occurs after the bulk liquid has disintegrated upon exiting the atomizer and is in the form of an ensemble of drops which undergo further breakup. The drop deformation and its eventual disintegration is important in evaluating the efficacy of a particular industrial process, be it combustion in automobile engines or pesticide spraying in agricultural applications. The interplay between competing influences of surface tension and aerodynamic disruptive forces is represented by the Weber number, We, and Ohnesorge number, Oh, and used to describe the breakup morphology. The breakup pattern considered in our study corresponds to that of a bag attached to a toroidal ring which occurs from ˜12 < We < ˜16. We aim to address several issues connected with this breakup process and their dependence on We and Oh which have been hitherto unexplored. The We boundary at which breakup begins is theoretically determined and the expression obtained, We = 12( {1 + 2/3 Oh^2 } ), is found to match well with experimental data {[L.-P. Hsiang and G. M. Faeth, Int. J. Multiphase Flow 21(4), 545-560 (1995)] and [R. S. Brodkey, "Formation of drops and bubbles," in The Phenomena of Fluid Motions (Addison-Wesley, Reading, 1967)]}. An exponential growth in the radial extent of the deformed drop and the streamline dimension of the bag is predicted by a theoretical model and confirmed by experimental findings. These quantities are observed to strongly depend on We. However, their dependence on Oh is weak.

  1. Bag breakup of low viscosity drops in the presence of a continuous air jet

    SciTech Connect

    Kulkarni, V. Sojka, P. E.

    2014-07-15

    This work examines the breakup of a single drop of various low viscosity fluids as it deforms in the presence of continuous horizontal air jet. Such a fragmentation typically occurs after the bulk liquid has disintegrated upon exiting the atomizer and is in the form of an ensemble of drops which undergo further breakup. The drop deformation and its eventual disintegration is important in evaluating the efficacy of a particular industrial process, be it combustion in automobile engines or pesticide spraying in agricultural applications. The interplay between competing influences of surface tension and aerodynamic disruptive forces is represented by the Weber number, We, and Ohnesorge number, Oh, and used to describe the breakup morphology. The breakup pattern considered in our study corresponds to that of a bag attached to a toroidal ring which occurs from ∼12 < We < ∼16. We aim to address several issues connected with this breakup process and their dependence on We and Oh which have been hitherto unexplored. The We boundary at which breakup begins is theoretically determined and the expression obtained, We=12(1+2/3Oh{sup 2}), is found to match well with experimental data ([L.-P. Hsiang and G. M. Faeth, Int. J. Multiphase Flow 21(4), 545–560 (1995)] and [R. S. Brodkey, “Formation of drops and bubbles,” in The Phenomena of Fluid Motions (Addison-Wesley, Reading, 1967)]). An exponential growth in the radial extent of the deformed drop and the streamline dimension of the bag is predicted by a theoretical model and confirmed by experimental findings. These quantities are observed to strongly depend on We. However, their dependence on Oh is weak.

  2. Invariant Coordinates in Breakup Reactions

    NASA Astrophysics Data System (ADS)

    Skwira-Chalot, I.; Ciepał, I.; Kistryn, St.; Kozela, A.; Parol, W.; Stephan, E.

    2017-03-01

    Systematic experimental studies of few-nucleon systems expose various dynamical ingredients which play an important role in correct description of observables, such as three-nucleon force, Coulomb force and relativistic effects. A large set of existing experimental data for ^1H(d, p p)n reaction allows for systematic investigations of these dynamical effects, which vary with energy and appear with different strength in certain observables and phase space regions. Moreover, systematic comparisons with exact theoretical calculations, done in variables related to the system dynamics in a possibly direct ways is a very important tool to verify and improve the existing description of the nucleon interaction. Examples of experimental data for a breakup reaction, transformed to the variables based on Lorentz-invariants are compared with modern theoretical calculations.

  3. Breakup Densities of Hot Nuclei.

    NASA Astrophysics Data System (ADS)

    Viola, Vic

    2006-04-01

    Breakup densities of hot ^197Au-like residues have been deduced from the systematic trends of Coulomb parameters required to fit intermediate-mass-fragment kinetic-energy spectra. The results indicate emission from nuclei near normal nuclear density below an excitation energy E*/A .3ex<˜x 2 MeV, followed by a gradual decrease to a near-constant value of ρ/ρ0˜ 3 for E*/A .3ex>˜x 5 MeV. Temperatures derived from these data with a density-dependent Fermi-gas model yield a nuclear caloric curve that is generally consistent with those derived from isotope ratios.

  4. Phenomenological model for light-projectile breakup

    NASA Astrophysics Data System (ADS)

    Kalbach, C.

    2017-01-01

    Background: Projectile breakup can make a large contribution to reactions induced by projectiles with mass numbers 2, 3, and 4, yet there is no global model for it and no clear agreement on the details of the reaction mechanism. Purpose: This project aims to develop a phenomenological model for light-projectile breakup that can guide the development of detailed theories and provide a useful tool for applied calculations. Method: An extensive database of double-differential cross sections for the breakup of deuterons, 3He ions, and α particles was assembled from the literature and analyzed in a consistent way. Results: Global systematics for the centroid energies, peak widths, and angular distributions of the breakup peaks have been extracted from the data. The dominant mechanism appears to be absorptive breakup, where the unobserved projectile fragment fuses with the target nucleus during the initial interaction. The global target-mass-number and incident-energy dependencies of the absorptive breakup cross section have also been determined, along with channel-specific normalization constants. Conclusions: Results from the model generally agree with the original data after subtraction of a reasonable underlying continuum. Absorptive breakup can account for as much as 50%-60% of the total reaction cross section.

  5. Design of Breakup Ice Control Structures

    DTIC Science & Technology

    2006-03-01

    ER D C/ CR R EL T R -0 6 -7 Design of Breakup Ice Control Structures Andrew M. Tuthill and James H. Lever March 2006 C ol d R eg...March 2006 Design of Breakup Ice Control Structures Andrew M. Tuthill and James H. Lever Cold Regions Research and Engineering Laboratory U.S. Army...ice control structure (ICS) is to retain a breakup ice run upstream of a traditional ice jam problem area and thereby miti- gate ice-jam flooding

  6. Breakup of finite thickness viscous shell microbubbles by ultrasound: A simplified zero-thickness shell model

    PubMed Central

    Hsiao, Chao-Tsung; Chahine, Georges L.

    2013-01-01

    A simplified three-dimensional (3-D) zero-thickness shell model was developed to recover the non-spherical response of thick-shelled encapsulated microbubbles subjected to ultrasound excitation. The model was validated by comparison with previously developed models and was then used to study the mechanism of bubble break-up during non-spherical deformations resulting from the presence of a nearby rigid boundary. The effects of the shell thickness and the bubble standoff distance from the solid wall on the bubble break-up were studied parametrically for a fixed insonification frequency and amplitude. A diagram of bubble shapes versus the normalized shell thickness and wall standoff was derived, and the potential bubble shapes at break-up from reentrant jets were categorized resulting in four distinct zones. PMID:23556560

  7. Polyphase Rifting and Breakup of the Central Mozambique Margin

    NASA Astrophysics Data System (ADS)

    Senkans, Andrew; Leroy, Sylvie; d'Acremont, Elia; Castilla, Raymi

    2017-04-01

    The breakup of the Gondwana supercontinent resulted in the formation of the Central Mozambique passive margin as Africa and Antarctica were separated during the mid-Jurassic period. The identification of magnetic anomalies in the Mozambique Basin and Riiser Larsen Sea means that post-oceanisation plate kinematics are well-constrained. Unresolved questions remain, however, regarding the initial fit, continental breakup process, and the first relative movements of Africa and Antarctica. This study uses high quality multi-channel seismic reflection profiles in an effort to identify the major crustal domains in the Angoche and Beira regions of the Central Mozambique margin. This work is part of the integrated pluri-disciplinary PAMELA project*. Our results show that the Central Mozambique passive margin is characterised by intense but localised magmatic activity, evidenced by the existence of seaward dipping reflectors (SDR) in the Angoche region, as well as magmatic sills and volcanoclastic material which mark the Beira High. The Angoche region is defined by a faulted upper-continental crust, with the possible exhumation of lower crustal material forming an extended ocean-continent transition (OCT). The profiles studied across the Beira high reveal an offshore continental fragment, which is overlain by a pre-rift sedimentary unit likely to belong to the Karoo Group. Faulting of the crust and overlying sedimentary unit reveals that the Beira High has recorded several phases of deformation. The combination of our seismic interpretation with existing geophysical and geological results have allowed us to propose a breakup model which supports the idea that the Central Mozambique margin was affected by polyphase rifting. The analysis of both along-dip and along-strike profiles shows that the Beira High initially experienced extension in a direction approximately parallel to the Mozambique coastline onshore of the Beira High. Our results suggest that the Beira High results

  8. Negative Emotions and Behaviors are Markers of Breakup Distress

    ERIC Educational Resources Information Center

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette

    2013-01-01

    Method: University students who experienced a recent romantic breakup were given several self-report measures and were then divided into high versus low breakup distress groups. Results: The high breakup distress versus the low breakup distress groups had higher scores on negative emotions scales including depression, anxiety and anger and…

  9. Negative Emotions and Behaviors are Markers of Breakup Distress

    ERIC Educational Resources Information Center

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette

    2013-01-01

    Method: University students who experienced a recent romantic breakup were given several self-report measures and were then divided into high versus low breakup distress groups. Results: The high breakup distress versus the low breakup distress groups had higher scores on negative emotions scales including depression, anxiety and anger and…

  10. Intrusive Thoughts: A Primary Variable in Breakup Distress

    ERIC Educational Resources Information Center

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2013-01-01

    University students who were high versus low on breakup distress scores were given self-report measures to assess their intrusive thoughts about the romantic breakup and their somatic symptoms that followed the breakup as well as their extracurricular activities and social support that might alleviate their breakup distress. In a regression…

  11. Intrusive Thoughts: A Primary Variable in Breakup Distress

    ERIC Educational Resources Information Center

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2013-01-01

    University students who were high versus low on breakup distress scores were given self-report measures to assess their intrusive thoughts about the romantic breakup and their somatic symptoms that followed the breakup as well as their extracurricular activities and social support that might alleviate their breakup distress. In a regression…

  12. ORFEUS alignment concept

    NASA Astrophysics Data System (ADS)

    Graue, R.; Kampf, D.; Rippel, H.; Witte, G.

    1991-09-01

    The alignment concept of ORFEUS, a short-term scientific space payload scheduled for launching by the STS in January 1993, is discussed. ORFEUS comprises two alternatively operating spectrometers (Echelle and Rowland) implemented in a CFC telescope with a 4-m tube length and an aperture of 1000 mm. The lightweight primary mirror has a focal length of 2426 mm. In order to achieve the required spectrometric high telescope resolution in the UV range (40-125 nm), a sophisticated alignment concept was developed. The centering of the alignment diaphragm (diameter: 15 microns) in the focus of the primary mirror has to be provided in the vertical tube position by means of an autocollimation telescope. The spectrometers have to be integrated into the horizontal telescope aligned within a special antigravity device to reduce optical surface deformations and to ensure the optical performance of the primary. The alignment of all optical components is to be performed in the visible spectral range.

  13. On the breakup of viscous liquid threads

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.

    1995-01-01

    A one-dimensional model evolution equation is used to describe the nonlinear dynamics that can lead to the breakup of a cylindrical thread of Newtonian fluid when capillary forces drive the motion. The model is derived from the Stokes equations by use of rational asymptotic expansions and under a slender jet approximation. The equations are solved numerically and the jet radius is found to vanish after a finite time yielding breakup. The slender jet approximation is valid throughout the evolution leading to pinching. The model admits self-similar pinching solutions which yield symmetric shapes at breakup. These solutions are shown to be the ones selected by the initial boundary value problem, for general initial conditions. Further more, the terminal state of the model equation is shown to be identical to that predicted by a theory which looks for singular pinching solutions directly from the Stokes equations without invoking the slender jet approximation throughout the evolution. It is shown quantitatively, therefore, that the one-dimensional model gives a consistent terminal state with the jet shape being locally symmetric at breakup. The asymptotic expansion scheme is also extended to include unsteady and inerticial forces in the momentum equations to derive an evolution system modelling the breakup of Navier-Stokes jets. The model is employed in extensive simulations to compute breakup times for different initial conditions; satellite drop formation is also supported by the model and the dependence of satellite drop volumes on initial conditions is studied.

  14. Breakup modes of the drops suspended in a vertical wind tunnel in presence of the horizontal electric field

    NASA Astrophysics Data System (ADS)

    Bhalwankar, Rohini; Deshpande, C. G.; Kamra, A. K.

    2017-02-01

    The influence of strong horizontal electric field (EH) on different stages of deformation and eventual breakup of the large water drops of 6.6, 7.0, and 7.25 mm diameter has been observed in a vertical wind tunnel using high-speed photography. Dumbbell, filament, and bag modes of drop breakup are observed when EH = 0. However, drops elongate in horizontal direction, mostly develop sharp curvature at their ends, eject a fine jet spray of tiny droplets, and ultimately break up into several droplets in EH = 500 kV m-1. Extreme elongation up to 29 mm is observed for a 7.0 mm diameter drop. Results show that the breakup time, i.e., the time from the drop's extreme prolate shape to its breakup in its final oscillation, ranges from 13 to 41 ms when EH = 0 and 57-105 ms when EH = 500 kV m-1. So although the lifetime of the drop since its suspension to breakup is reduced, its elongation and breakup time increase in EH. It suggests that the effect of EH in final oscillation before breakup overcomes the effect of hydrodynamic and aerodynamic forces in elongating the drop. Also, no breakup of bag type is observed in EH = 500 kV m-1. Moreover, the fragments formed after the drop breakup and tiny droplets ejected by their fragments carry electrical charges of polarity determined by the induced charge on the parent drop in EH. The significance of the results is discussed in modifying the drop growth and the radar echo-precipitation relationships in thunderclouds.

  15. Numerical simulations of the early stages of high-speed droplet breakup

    NASA Astrophysics Data System (ADS)

    Meng, J. C.; Colonius, T.

    2015-07-01

    Experiments reported in the literature are reproduced using numerical simulations to investigate the early stages of the breakup of water cylinders in the flow behind normal shocks. Qualitative features of breakup observed in the numerical results, such as the initial streamwise flattening of the cylinder and the formation of tips at its periphery, support previous experimental observations of stripping breakup. Additionally, the presence of a transitory recirculation region at the cylinder's equator and a persistent upstream jet in the wake is noted and discussed. Within the uncertainties inherent to the different methods used to extract measurements from experimental and numerical results, comparisons with experimental data of various cylinder deformation metrics show good agreement. To study the effects of the transition between subsonic and supersonic post-shock flow, we extend the range of incident shock Mach numbers beyond those investigated by the experiments. Supersonic post-shock flow velocities are not observed to significantly alter the cylinder's behavior, i.e., we are able to effectively collapse the drift, acceleration, and drag curves for all simulated shock Mach numbers. Using a new method that minimizes noise errors, the cylinder's acceleration is calculated; acceleration curves for all shock Mach numbers are subsequently collapsed by scaling with the pressure ratio across the incident shock. Furthermore, we find that accounting for the cylinder's deformed diameter in the calculation of its unsteady drag coefficient allows the drag coefficient to be approximated as a constant over the initial breakup period.

  16. Drop Breakup in the Flow Through Fixed Beds

    NASA Astrophysics Data System (ADS)

    Mosler, Alisa B.; Shaqfeh, Eric S. G.

    1996-11-01

    The flow through a dilute, disordered fixed bed of fibers has been shown to produce large polymer conformation change beyond a certain critical flow rate^1. We now examine the effect of this flow on the shape and breakup of viscous drops. The stochastic, Lagrangian time-varying flow through fixed beds is of particular interest since it may efficiently induce drop fragmentation and is used as a practical means of emulsification and the mixing of liquid phases. Because the flow through a dilute fixed bed is equivalent to a certain anisotropic Gaussian flow field^1, a model of the flow is reproduced through a spectral expansion where the wave number vectors are chosen from statistical distributions which ensure that the desired velocity field will be realized^2. We examine the dynamics of model drop shapes (whose surface is represented via small deformation theory^3, 4), averaged over the Gaussian statistics of the flow field, by synthesizing a large number of flow realizations. We demonstrate that the flow through fixed beds is indeed ``strong'' since beyond a certain value of the pore-size Capillary number, Ca ~ 0.2, no steady average solution for the drop shape exists. We shall go on to discuss the mechanisms of this flow-induced breakup. ^1 Shaqfeh and Koch (1992), ^2 Mosler and Shaqfeh (1996), ^3 Taylor (1932, 1934), ^4 Barthès-Biesel and Acrivos (1973)

  17. Inferences Concerning the Magnetospheric Source Region for Auroral Breakup

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1992-01-01

    It is argued that the magnetospheric source region for auroral arc breakup and substorm initiation is along boundary plasma sheet (BPS) magnetic field lines. This source region lies beyond a distinct central plasma sheet (CPS) region and sufficiently far from the Earth that energetic ion motion violates the guiding center approximation (i.e., is chaotic). The source region is not constrained to any particular range of distances from the Earth, and substorm initiation may be possible over a wide range of distances from near synchronous orbit to the distant tail. It is also argued that the layer of low-energy electrons and velocity dispersed ion beams observed at low altitudes on Aureol 3 is not a different region from the region of auroral arcs. Both comprise the BPS. The two regions occasionally appear distinct at low altitudes because of the effects of arc field-aligned potential drops on precipitating particles.

  18. Shear stabilization of the capillary breakup of a cylindrical interface

    NASA Technical Reports Server (NTRS)

    Russo, Mathew J.; Steen, Paul H.

    1989-01-01

    A cylindrical interface containing a viscous liquid set into axial motion is subject to a capillary and to a surface-wave instability. Clues from previous studies suggest that, even though both mechanisms separately are destabilizing, under certain circumstances their mutual interaction can lead to a stable interface; shear can stabilize capillary breakup. Here, an axial flow through an annular cross section bounded on the inside by a rigid rod and on the outside by a deformable interface is considered. The competition between the two mechanisms is studied through the temporal growth of infinitesimal axisymmetric and nonaxisymmetric disturbances. This examination of temporal stability shows that, indeed, for geometries corresponding to thin annular layers both instabilities can be completely suppressed (disturbances of all wavelengths decay).

  19. How is continental break-up recorded in magma-poor rifted margins?

    NASA Astrophysics Data System (ADS)

    Peron-Pinvidic, G.; Manatschal, G.; Minshull, T.; Sawyer, D.

    2006-12-01

    In classical models of continental break-up, rifting is immediately followed by seafloor spreading, which implies that break-up can be identified as a specific spatial and temporal boundary. However, this simple concept is not supported by observations at rifted margins. The classical indicators for determining break-up (break-up unconformity, magnetic anomalies, distribution of high-angle faults and sedimentary wedges) may no longer be relied upon to identify unambiguously the location and age of break-up. We studied the spatial and temporal evolution of the deep Iberia-Newfoundland margins, which are the type examples of magma-poor rifted margins. Our study was based on borehole data and on a mapping of the sedimentary and basement architecture in 3D on seismic reflection profiles. Our results allow us to describe the tectono-sedimentary and morpho-tectonic evolution of final rifting and show that continental break-up is complex. In the Iberia-Newfoundland rift system, the tectono-sedimentary evolution of final rifting can be reconstructed back to 145Ma, when the crust was already thinned to less than 10km. Two major deformation phases have been identified: a first, Tithonian to Barremian in age (145-128Ma) and a second, dated as latest Aptian (112Ma). The Tithonian-Barremian phase is characterized by a migration of the tectonic activity oceanwards and a change of the deformation mechanisms from south to north, from zones of mantle exhumed via downward concave faults to classical half-grabens formed by the normal tilting of thinned continental blocks along upward concave faults. This phase terminates with the formation of the first unequivocal magnetic anomaly (M3 128Ma) and the accretion of more than 170km of crust, at rates of about 1cm/yr, that is neither oceanic nor continental, commonly referred to as Zone of Exhumed Continental Mantle (ZECM). The late-Aptian phase is associated with a major tectono-magmatic event and is responsible for the observed basement

  20. Evidence for a Battle Mountain-Eureka crustal fault zone, north-central Nevada, and its relation to Neoproterozoic-Early Paleozoic continental breakup

    USGS Publications Warehouse

    Grauch, V.J.S.; Rodriguez, B.D.; Bankey, V.; Wooden, J.L.

    2003-01-01

    Combined evidence from gravity, radiogenic isotope, and magnetotelluric (MT) data indicates a crustal fault zone that coincides with the northwest-trending Battle Mountain-Eureka (BME) mineral trend in north-central Nevada, USA. The BME crustal fault zone likely originated during Neoproterozoic-Early Paleozoic rifting of the continent and had a large influence on subsequent tectonic events, such as emplacement of allochthons and episodic deformation, magmatism, and mineralization throughout the Phanerozoic. MT models show the fault zone is about 10 km wide, 130-km long, and extends from 1 to 5 km below the surface to deep crustal levels. Isotope data and gravity models imply the fault zone separates crust of fundamentally different character. Geophysical evidence for such a long-lived structure, likely inherited from continental breakup, defies conventional wisdom that structures this old have been destroyed by Cenozoic extensional processes. Moreover, the coincidence with the alignment of mineral deposits supports the assertion by many economic geologists that these alignments are indicators of buried regional structures.

  1. Evaluation of Reentry Breakup and Debris Generation

    NASA Astrophysics Data System (ADS)

    Nyman, R. L.

    2012-01-01

    Orbital missions launching from Cape Canaveral typically overfly Europe or African before achieving orbital insertion and pose a risk that must be evaluated as part of the overall mission casualty expectation. During the downrange overflight phase, the vehicle is well above the atmosphere and has achieved near orbital velocity, consequently a loss of thrust, loss of control or high altitude breakup will bring either the intact upper stage or smaller secondary debris fragments into the atmosphere and subject them to intense aerodynamic heating. In order to make reasonable risk estimates, it is necessary to first predict the reentry breakup characteristics and the survival of debris fragments. ACTA has developed the Coupled Aeroheating and Thermal Network Solver (CATNS) code to help range safety analysts evaluate reentry breakup and demise.

  2. Inclusive Proton Emission Spectra from Deuteron Breakup Reactions

    NASA Astrophysics Data System (ADS)

    Carlson, B. V.; Capote, R.; Sin, M.

    2016-05-01

    We present calculations of deuteron elastic and nonelastic breakup cross sections and angular distributions at deuteron energies below 100 MeV obtained using the post-form DWBA approximation. The elastic breakup cross section was extensively studied in the past. Very few calculations of nonelastic breakup have been performed, however. We compare two forms of the elastic DWBA breakup amplitude but conclude that neither provides a correct description of the inclusive proton emission cross section.

  3. Nanojets: Electrification, Energetics, Dynamics, Stability and Breakup

    DTIC Science & Technology

    2006-12-31

    20/2007 FINAL 02/15/2004-12/31/2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Nanojets: Electrification , Energetics, Dynamics, Stability and Breakup...NUMBER finclude area code)UUU64 404.894.3368 Standard Form 298 (Rev. 8/98) Prescribed by ANSI SId. Z39.18 FINAL REPORT Nanojets: Electrification

  4. Breakup branches of Borromean beryllium-9

    SciTech Connect

    Smith, R. Freer, M.; Wheldon, C.; Curtis, N.; Ashwood, N. I.; Barr, M.; Kokalova, Tz.; Malcolm, J. D.; Ziman, V. A.; Almaraz-Calderon, S.; Aprahamian, A.; Bucher, B.; Couder, M.; Fang, X.; Jung, F.; Lu, W.; Roberts, A.; Tan, W. P.; Copp, P.; Lesher, S. R.; and others

    2015-10-15

    The breakup reaction {sup 9}Be({sup 4}He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in {sup 9}Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in {sup 9}Be have been explored including the {sup 8}Be{sub g.s.} + n, {sup 8}Be{sub 2{sup +}} + n and {sup 5}He{sub g.s.} + {sup 4}He channels. By imposing the condition that the breakup proceeded via the {sup 8}Be ground state, clean excitation spectra for {sup 9}Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose.

  5. Breakup branches of Borromean beryllium-9

    NASA Astrophysics Data System (ADS)

    Smith, R.; Freer, M.; Wheldon, C.; Curtis, N.; Almaraz-Calderon, S.; Aprahamian, A.; Ashwood, N. I.; Barr, M.; Bucher, B.; Copp, P.; Couder, M.; Fang, X.; Goldring, G.; Jung, F.; Kokalova, Tz.; Lesher, S. R.; Lu, W.; Malcolm, J. D.; Roberts, A.; Tan, W. P.; Ziman, V. A.

    2015-10-01

    The breakup reaction 9Be(4He, 3α)n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in 9Be up to 12 MeV were populated and reconstructed through the measurement of the charged reaction products. It is proposed that limits on the spins and parities of the states can be derived from the way that they decay. Various breakup paths for excited states in 9Be have been explored including the 8Beg.s. + n, 8Be2+ + n and 5Heg.s. + 4He channels. By imposing the condition that the breakup proceeded via the 8Be ground state, clean excitation spectra for 9Be were reconstructed. The remaining two breakup channels were found to possess strongly-overlapping kinematic signatures and more sophisticated methods (referenced) are required to completely disentangle these other possibilities. Emphasis is placed on the development of the experimental analysis and the usefulness of Monte-Carlo simulations for this purpose.

  6. Supercontinent break-up: Causes and consequences

    NASA Astrophysics Data System (ADS)

    Li, Z. X.

    2014-12-01

    Supercontinent break-up has most commonly been linked to plume or superplume events, and/or supercontinent thermal insulation, but precise mechanisms are yet to be worked out. Even less know is if and what roles other factors may play. Key factors likely include gravitational force due to the continental superswell driven by both the lower-mantle superplume and continental thermal insulation, mental convention driven by the superplume and individual plumes atop the superplume, assisted by thermal/magmatic weakening of the supercontinent interior (both plume heat and thermal insulation heat). In addition, circum-supercontinent slab downwelling may not only drive the formation of the antipodal superplumes (thus the break-up of the supercontinent), the likely roll-back of the subduction system would also create extension within the supercontinent, facilitating supercontinent break-up. Consequences of supercontinent break-up include long-term sea-level rise, climatic changes due to changes in ocean circulation pattern and carbon cycle, and biodiversification. It has long been demonstrated that the existence of the supercontinent Pangea corresponds to a long-term sea-level drop, whereas the break-up of the supercontinent corresponds to a long-term sea-level rise (170 m higher than it is today). A recent analysis of Neoproterozoic sedimentary facies illustrates that the time of Neoproterozoic supercontinent Rodinia corresponds to a low in the percentage of deep marine facies occurrence, whereas the time of Rodinia break-up corresponds to a significantly higher percentage of deep marine facies occurrence. The long-tern sea-level drop during supercontinent times were likely caused by both plume/superplume dynamic topography and an older mean age of the oceanic crust, whereas long-tern sea-level rise during supercontinent break-up (720-580 Ma for Rodinia and Late Jurassic-Cretaceous for Pangea) likely corresponds to an younger mean age of the oceanic crust, massive plume

  7. Entrainment instability and vertical motion as causes of stratocumulus breakup

    NASA Technical Reports Server (NTRS)

    Weaver, C. J.; Pearson, R., Jr.

    1990-01-01

    Entrainment instability is thought to be a cause of stratocumulus breakup. At the interface between the cloud and the overlying air, mixtures may form which are negatively buoyant because of cloud droplet evaporation. Quantities devised to predict breakup are obtained from aircraft observations and are tested against cloud observations from satellite. Often, the parameters indicate that breakup should occur but the clouds remain, sometimes for several days. One possible explanation for breakup is vertical motion from passing synoptic cyclones. Several cases suggest that breakup is associated with the downward vertical motion from the cold air advected behind an eastward moving cyclone.

  8. The break-up of continents and the formation of new ocean basins.

    PubMed

    Minshull, T A

    2002-12-15

    Rifted continental margins are the product of stretching, thinning and ultimate break-up of a continental plate into smaller fragments, and the rocks lying beneath them store a record of this rifting process. Earth scientists can read this record by careful sampling and with remote geophysical techniques. These experimental studies have been complemented by theoretical analyses of continental extension and associated magmatism. Some rifted margins show evidence for extensive volcanic activity and uplift during rifting; at these margins, the record of the final stages of rifting is removed by erosion and obscured by the thick volcanic cover. Other margins were underwater throughout their formation and showed rather little volcanic activity; here the ongoing deposition of sediment provides a clearer record. During the last decade, vast areas of exhumed mantle rocks have been discovered at such margins between continental and oceanic crust. This observation conflicts with the well-established idea that the mantle melts to produce new crust when it is brought close to the Earth's surface. In contrast to the steeply dipping faults commonly seen in zones of extension within continental interiors, faults with very shallow dips play a key role in the deformation immediately preceding continental break-up. Future progress in the study of continental break-up will depend on studies of pairs of margins which were once joined and on the development of computer models which can handle rigorously the complex transition from distributed continental deformation to sea-floor spreading focused at a mid-ocean ridge.

  9. Modification of the alignment between the tibial tubercle and the trochlear groove induced by temporary hemiepiphysiodesis for lower extremity angular deformities: a trigonometric analysis.

    PubMed

    Ceroni, Dimitri; Dhouib, Amira; Merlini, Laura; Kampouroglou, Georgios

    2016-12-09

    This study aimed to predict the modification of the alignment between the tibial tubercle (TT) and the trochlear groove (TG) that occurs during femoral or tibial hemiepiphysiodesis. MRI scans of 541 knees were retrospectively reviewed to determine the distances between the cranial insertion of the patellar tendon on the TT and the femoral physis (FP)/tibial physis (TP). Thereafter, we developed a trigonometric formula to calculate the predicted change of the TT-TG distance that occurs during hemiepiphysiodesis around the knee using both the planned angular correction as well as the length between the physis (both distal femoral and proximal tibial) and the insertion of the patellar tendon of the TT. This study showed that TT-FP and TT-TP distances vary very little with sex and age during growth and the mean values of FP-TT and TP-TT distances (55 and 7 mm, respectively) can thus be used in clinical settings for calculating a rough estimate of the translation of the TT position that will occur during 'guided growth'. On this subject, one can expect a 1 mm simultaneous lateral or medial transfer of the TT for every 1° of angular correction during distal femoral hemiepiphysiodesis. For proximal tibial hemiepiphysiodesis, an angular correction of 8° should roughly translate into a simultaneous 1 mm transfer of the TT. This study puts forward the hypothesis that a simultaneous modification of the TT-TG distance has to be expected following hemiepiphysiodesis, whether femoral or tibial.

  10. Post-breakup Basin Evolution along the South-Atlantic Margins

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2014-05-01

    The post-breakup tectono-stratigraphic evolution of large offshore basins along the South American and African continental margins record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. A regional comparison based on tectonic-stratigraphic analysis of selected seismic transects between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin) provides a comprehensive basin-to-basin documentation of the key geological parameters controlling ocean and continental margin development. This comparison includes the margin configuration, subsidence development through time, sediment influx and storage patterns, type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems) and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development. The diversity in the stratigraphic architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are (a) the structural configuration of each margin segment at the time of break-up, (b) the post break-up subsidence history of the respective margin segment

  11. Differential approach to Capillary Breakup Rheometry: role of filament asymmetry induced by sample volume and strain

    NASA Astrophysics Data System (ADS)

    McCarroll, Louise; Schultz, William; Solomon, Michael

    2015-11-01

    We investigate the operating range of the 1-D, Newtonian, differential analysis for capillary breakup rheometry. Capillary breakup rheometry (CBR) derives specimen physical properties (e.g. viscosity) from measurements of the filament evolution after a sudden deformation. In our differential analysis, derivatives of the filament radius as a function of the axial coordinate and time are measured to determine the ratio of surface tension to viscosity. We evaluate the accuracy of the differential method by applying it to Newtonian fluids with a range of viscosities and for experiments with different sample volumes and strains. We investigate the impact of filament asymmetry on the performance of the differential method for the range of conditions studied and with a 1-D numerical model. This evaluation yields recommendations for using the differential CBR technique. We discuss the scope for extending the differential analysis to more complex cases, such as for insoluble surfactant at the fluid-air interface.

  12. Modeling breakup and relaxation of Newtonian droplets using the advected phase-field approach

    NASA Astrophysics Data System (ADS)

    Beaucourt, J.; Biben, T.; Leyrat, A.; Verdier, C.

    2007-02-01

    The relaxation and breakup of Newtonian droplets is considered using the advected field approach. This method allows one to follow the deformation of interfaces using an order parameter field [Biben , Europhys. Lett. 63, 623 (2003)] based on a Ginzburg-Landau equation. Using this method, it is possible to follow the breakup of droplets and stability curves can be obtained in both two- and three-dimensional shear and elongational flows. Finally, relaxation of a droplet is considered, following the application of an elongational flow. The results are compared with previous experimental data [Ha and Leal, Phys. Fluids 13, 1568 (2001)], and are found to be in satisfactory agreement. The method is general enough to be applied to other non-Newtonian fluids, such as Oldroyd-B fluids or viscoplastic materials.

  13. Microfluidic breakups of confined droplets against a linear obstacle: The importance of the viscosity contrast.

    PubMed

    Salkin, Louis; Courbin, Laurent; Panizza, Pascal

    2012-09-01

    Combining experiments and theory, we investigate the break-up dynamics of deformable objects, such as drops and bubbles, against a linear micro-obstacle. Our experiments bring the role of the viscosity contrast Δη between dispersed and continuous phases to light: the evolution of the critical capillary number to break a drop as a function of its size is either nonmonotonic (Δη>0) or monotonic (Δη≤0). In the case of positive viscosity contrasts, experiments and modeling reveal the existence of an unexpected critical object size for which the critical capillary number for breakup is minimum. Using simple physical arguments, we derive a model that well describes observations, provides diagrams mapping the four hydrodynamic regimes identified experimentally, and demonstrates that the critical size originating from confinement solely depends on geometrical parameters of the obstacle.

  14. Ice breakup: Observations of the acoustic signal

    NASA Astrophysics Data System (ADS)

    Waddell, S. R.; Farmer, D. M.

    1988-03-01

    We describe observations of ambient sound beneath landfast ice in the Canadian Arctic Archipelago and interpret its evolution over the period June-August in terms of ice cracking and disintegration. The data were recorded on six bands between 50 and 14,500 Hz for the period April 2 to August 7, 1986, in Dolphin and Union Strait. The frequency dependence of the attenuation of sound in water allows separation of distant and local noise sources. In conjunction with satellite imagery and meteorological data, it is shown that strong signals in the acoustic time series are associated with major breakup events. The acoustic signal can provide predictive information about ice conditions and the approach of breakup.

  15. Coupled map lattice model of jet breakup

    SciTech Connect

    Minich, R W; Schwartz, A J; Baker, E L

    2001-01-25

    An alternative approach is described to evaluate the statistical nature of the breakup of shaped charge liners. Experimental data from ductile and brittle copper jets are analyzed in terms of velocity gradient, deviation of {Delta}V from linearity, R/S analysis, and the Hurst exponent within the coupled map lattice model. One-dimensional simulations containing 600 zones of equal mass and using distinctly different force-displacement curves are generated to simulate ductile and brittle behavior. A particle separates from the stretching jet when an element of material reaches the failure criterion. A simple model of a stretching rod using brittle, semi-brittle, and ductile force-displacement curves is in agreement with the experimental results for the Hurst exponent and the phase portraits and indicates that breakup is a correlated phenomenon.

  16. Breakup of Pack Ice, Antarctic Ice Shelf

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Breakup of Pack Ice along the periphery of the Antarctic Ice Shelf (53.5S, 3.0E) produced this mosaic of ice floes off the Antarctic Ice Shelf. Strong offshore winds, probably associated with strong katabatic downdrafts from the interior of the continent, are seen peeling off the edges of the ice shelf into long filamets of sea ice, icebergs, bergy bits and growlers to flow northward into the South Atlantic Ocean. 53.5S, 3.0E

  17. Confinement and viscosity ratio effect on droplet break-up in a concentrated emulsion flowing through a narrow constriction

    NASA Astrophysics Data System (ADS)

    Khor, Jian Wei; Gai, Ya; Tang, Sindy

    2016-11-01

    We describe the dimensionless groups that determine the break-up probability of droplets in a concentrated emulsion during its flow in a tapered microchannel consisting of a narrow constriction. Such channel geometry is commonly used in droplet microfluidics to investigate the content of droplets from a concentrated emulsion. In contrast to solid wells in multi-well plates, drops are metastable, and are prone to break-up which compromises the accuracy and the throughput of the assay. Unlike single drops, the break-up process in a concentrated emulsion is stochastic. Analysis of the behavior of a large number of drops (N >5000) shows that the probability of break-up increases with applied flow rate, the size of the drops relative to the size of the constriction, and the viscosity ratio of the emulsion. We found that the break-up probability collapses into a single curve when plotted as a function of the product of capillary number, viscosity ratio, and confinement factor defined as the un-deformed radius of the drop relative to the hydraulic radius of the constriction. The results represent a critical step towards the understanding of the physics governing instability in concentrated emulsions.

  18. The Break-up and Drifting of the Continental Plates in 2D Models of Convecting Mantle

    NASA Astrophysics Data System (ADS)

    Dal Zilio, L.; Faccenda, M.; Capitanio, F. A.

    2014-12-01

    Since the early theory of Wegener, the break-up and drift of continents have been controversial and hotly debated topics. To assist the interpretation of the break-up and drift mechanisms and its relation with mantle circulation patterns, we carried out a 2D numerical modelling of the dynamics of these processes. Different regimes of upper plate deformation are studied as consequence of stress coupling with convection patterns. Subduction of the oceanic plate and induced mantle flow propagate basal tractions to the upper plate. This mantle drag forces (FMD) can be subdivided in two types: (1) active mantle drag occurring when the flow drives plate motion (FAD), and (2) passive mantle drag (FPD), when the asthenosphere resists plate motion. The active traction generated by the convective cell is counterbalanced by passive mantle viscous drag away from it and therefore tension is generated within the continental plate. The shear stress profiles indicate that break-up conditions are met where the gradient of the basal shear stress is maximised, however the break-up location varies largely depending on the convection style primarily controlled by slab stagnation on the transition zone, avalanching through or subduction in the lower mantle. We found good correspondence between our models and the evolution of convergent margins on Earth, giving precious insights into the break-up and drifting mechanisms of some continental plates, such as the North and South American plates, Calabria and the Japan Arc.

  19. Beam Breakup Effects in Dielectric Based Accelerators

    SciTech Connect

    Schoessow, P.; Kanareykin, A.; Jing, C.; Kustov, A.; Altmark, A.; Power, J. G.; Gai, W.

    2009-01-22

    The dynamics of the beam in structure-based wakefield accelerators leads to beam stability issues not ordinarily found in other machines. In particular, the high current drive beam in an efficient wakefield accelerator loses a large fraction of its energy in the decelerator structure, resulting in physical emittance growth, increased energy spread, and the possibility of head-tail instability for an off axis beam, all of which can lead to severe reduction of beam intensity. Beam breakup (BBU) effects resulting from parasitic wakefields provide a potentially serious limitation to the performance of dielectric structure based wakefield accelerators as well. We report on experimental and numerical investigation of BBU and its mitigation. The experimental program focuses on BBU measurements at the AWA facility in a number of high gradient and high transformer ratio wakefield devices. New pickup-based beam diagnostics will provide methods for studying parasitic wakefields that are currently unavailable. The numerical part of this research is based on a particle-Green's function beam breakup code we are developing that allows rapid, efficient simulation of beam breakup effects in advanced linear accelerators. The goal of this work is to be able to compare the results of detailed experimental measurements with the accurate numerical results and to design an external FODO channel for the control of the beam in the presence of strong transverse wakefields.

  20. Reconciling Coulomb breakup and neutron radiative capture

    NASA Astrophysics Data System (ADS)

    Capel, P.; Nollet, Y.

    2017-07-01

    The Coulomb-breakup method to extract the cross section for neutron radiative capture at astrophysical energies is analyzed in detail. In particular, its sensitivity to the description of the neutron-core continuum is ascertained. We consider the case of 14C(n ,γ )15C for which both the radiative capture at low energy and the Coulomb breakup of 15C into 14C+n on Pb at 68 MeV/nucleon have been measured with accuracy. We confirm the direct proportionality of the cross section for both reactions to the square of the asymptotic normalization constant of 15C observed by Summers and Nunes [Phys. Rev. C 78, 011601(R) (2008), 10.1103/PhysRevC.78.011601], but we also show that the 14C-n continuum plays a significant role in the calculations. Fortunately, the method proposed by Summers and Nunes can be improved to absorb that continuum dependence. We show that a more precise radiative-capture cross section can be extracted selecting the breakup data at forward angles and low 14C-n relative energies.

  1. Ice multiplication by mechanical breakup and lightning

    NASA Astrophysics Data System (ADS)

    Phillips, Vaughan; Yano, Jun-Ichi

    2016-04-01

    Laboratory studies have proven the existence of several pathways for fragmentation of ice. One of these is the rime-splintering of graupel or hail in the -3 to -8 degC region (the Hallett-Mossop process). In some clouds, however, the cloud-base is too cold for this process to be active. Instead, breakup can occur by fragmentation of ice mechanically in re-bounding collisions between crystals, snow, graupel or hail. A new theoretical formulation of this mechanical breakup process of multiplication is presented for these types of ice. A numerical scheme is derived by simulation of published laboratory experiments. The role of such breakup in clouds is quantified by 3D simulations with a cloud-resolving aerosol-cloud model with emulated bin microphysics, detailed treatment of ice morphology and 7 chemical species of aerosol. Graupel-graupel collisions are predicted to produce copious numbers of ice crystals in the cold-base convective cloud simulated over Kansas. Implications for lightning from such multiplication, also simulated numerically, are discussed.

  2. The Beam Break-Up Numerical Simulator

    SciTech Connect

    Travish, G.A.

    1989-11-01

    Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs.

  3. Marine particle aggregate breakup in turbulent flows

    NASA Astrophysics Data System (ADS)

    Rau, Matthew; Ackleson, Steven; Smith, Geoffrey

    2016-11-01

    The dynamics of marine particle aggregate formation and breakup due to turbulence is studied experimentally. Aggregates of clay particles, initially in a quiescent aggregation tank, are subjected to fully developed turbulent pipe flow at Reynolds numbers of up to 25,000. This flow arrangement simulates the exposure of marine aggregates in coastal waters to a sudden turbulent event. Particle size distributions are measured by in-situ sampling of the small-angle forward volume scattering function and the volume concentration of the suspended particulate matter is quantified through light attenuation measurements. Results are compared to measurements conducted under laminar and turbulent flow conditions. At low shear rates, larger sized particles indicate that aggregation initially governs the particle dynamics. Breakup is observed when large aggregates are exposed to the highest levels of shear in the experiment. Models describing the aggregation and breakup rates of marine particles due to turbulence are evaluated with the population balance equation and results from the simulation and experiment are compared. Additional model development will more accurately describe aggregation dynamics for remote sensing applications in turbulent marine environments.

  4. Force Required to Breakup a Continent: Implications on Rifting Localization and Migration

    NASA Astrophysics Data System (ADS)

    Svartman Dias, A. E.; Lavier, L. L.; Hayman, N. W.

    2014-12-01

    The maximum force from ridge push available is about 5 TN/m, lower than that required by 2D and 3D numerical experiments to rift the lithosphere in the absence of magmatic input. We carry out 2D numerical experiments without any magmatic input to study the extensional force necessary to start a rift basin and to breakup a continent. We assume a range of initial temperature structure, crust and mantle initial thicknesses and composition. In a first step, we use velocity boundary conditions (1cm/yr) and we monitor the force necessary to breakup the continent. Results can be classified in two groups according to the amount of force needed to rift through time: (1) The initial force builds up rapidly to 12-20 TN/m within 0.4-1.0 Myr. This is followed by an exponential decrease due to early strain localization and lithospheric weakening. The force is < 5TN/m after 4.4-7.0 Myr of extension. Continental breakup occurs approximately 10 Myr after the onset of extension forming narrow conjugate margins. This group encompasses experiments with initial Tmoho < 650oC and crustal thicknesses ≤ 35 km, where crust and mantle deformation are coupled from the early stages of rifting. (2) The initial build-up is more discrete, from < 3 TN/m to 4-6.5 TN/m in the first 0.1 Myr, followed by a decrease to a nearly constant value of 3-5 TN/m from 0.4 Myr to 10 Myr, when strain starts localizing. The constant force through time reflects lithosphere strengthening and migration of the deformation. This rift migration forms a wide basin (> 250 km wide) that may evolve to form very asymmetric conjugate margins. Breakup occurs 18 Myr after the onset of rifting or later. This second group corresponds to experiments with initial Tmoho > 650 km and crustal thicknesses ≥ 35 km. High bending stresses result in upper crust brittle failure and on enhancement of lower crust lateral flow. Interaction between ductile failure in the lower crust and brittle failure in the upper crust controls the

  5. Prediction of the critical point of pressure-induced deformation-related phase transitions in aligned single-walled carbon nanotubes on the basis of extreme-low-frequency-shift Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Shen, Yanting; Zerulla, Dominic

    2017-05-01

    Experimental evidence investigating the high-pressure response (0-9 GPa) of aligned single-walled carbon nanotube (SWNT) arrays in the extreme low Raman shift region (10-100 cm-1, squash mode region) is provided to verify a predictive model for deformation-related phase transitions. In addition to the well-known radial breathing mode (RBM) and despite the technical challenges associated with the detection of Raman signals very close to the exciting laser frequency, clear SWNT squash mode peaks were identified and used to refine the predictive model. Furthermore, this paper investigates and proposes explanations for the detailed behavior of the pressure dependent cross-sectional transition. The results demonstrate experimentally, and confirm earlier theoretical models, that the critical pressure scales ∝1 /O (dt3) against the chirality dependent nanotube diameter dt. Finally, the pressure and chirality dependent Raman upshifts of the squash mode, characterizing the phase transition, are found to be larger than those of the RBM, respectively, confirming the general theoretical prediction of greater environmental sensitivity of squash modes.

  6. An Adaptive Mesh Algorithm for Evolving Surfaces: Simulations of Drop Breakup and Coalescence

    NASA Astrophysics Data System (ADS)

    Cristini, Vittorio; Bławzdziewicz, Jerzy; Loewenberg, Michael

    2001-04-01

    An algorithm is presented for the adaptive restructuring of meshes on evolving surfaces. The resolution of the relevant local length scale is maintained everywhere with prescribed accuracy through the minimization of an appropriate mesh energy function by a sequence of local restructuring operations. The resulting discretization depends on the instantaneous configuration of the surface but is insensitive to the deformation history. Application of the adaptive discretization algorithm is illustrated with three-dimensional boundary-integral simulations of deformable drops in Stokes flow. The results show that the algorithm can accurately resolve detailed features of deformed fluid interfaces, including slender filaments associated with drop breakup and dimpled regions associated with drop coalescence. Our algorithm should be useful in a variety of fields, including computational fluid dynamics, image processing, geographical information systems, and biomedical engineering problems.

  7. Alignment validation

    SciTech Connect

    ALICE; ATLAS; CMS; LHCb; Golling, Tobias

    2008-09-06

    The four experiments, ALICE, ATLAS, CMS and LHCb are currently under constructionat CERN. They will study the products of proton-proton collisions at the Large Hadron Collider. All experiments are equipped with sophisticated tracking systems, unprecedented in size and complexity. Full exploitation of both the inner detector andthe muon system requires an accurate alignment of all detector elements. Alignmentinformation is deduced from dedicated hardware alignment systems and the reconstruction of charged particles. However, the system is degenerate which means the data is insufficient to constrain all alignment degrees of freedom, so the techniques are prone to converging on wrong geometries. This deficiency necessitates validation and monitoring of the alignment. An exhaustive discussion of means to validate is subject to this document, including examples and plans from all four LHC experiments, as well as other high energy experiments.

  8. Substorm Onset and the Possible Role of O+ IONS Flowing out during Pseudo-Breakup Auroras

    NASA Astrophysics Data System (ADS)

    Parks, G. K.; Lee, E.; Fillingim, M. O.; Fu, S.; Cui, Y.; Hong, J.

    2014-12-01

    An isolated substorm onset event that occurred on 14 February 2001 was recorded by the WIC on IMAGE. WIC observed an enhanced electron precipitation region that grew out of a pseudo-breakup auroral spot at the poleward boundary that moved southward and activitated an aurora. An isolated substorm onset was triggered when the pseudo-breakup region connected to the activitated aurora at the lower boundary. This observation is a global scale phenomenon, whose behavior is similar but also different from observations of north-south motion at smaller localized scales that precede the onset of substorms (Nishimura et al., 2010). Fortuitously, Cluster during this pseudo-break auroral activity, detected escape of low energy (20-50 eV) field-aligned O+ ions. The triggered onset was accompanied by the escape of more energetic O+ (80 eV -300 eV) ions. Our observations suggest that the escaping O+ ions during pseudo-breakup auroras may be the seed for the onset of isolated substorms needed in some simulation models (Winglee and Harnett, 2010).

  9. Satellites in the inviscid breakup of bubbles.

    PubMed

    Gordillo, J M; Fontelos, M A

    2007-04-06

    In this Letter, we stress the essential role played by gas inertia in the breakup of gas bubbles. Our results reveal that, whenever the gas to liquid density ratio Lambda=rhog/rhol is different from zero, tiny satellite bubbles may be formed as a result of the large gas velocities that are reached close to pinch-off. Moreover, we provide a closed expression for the characteristic satellite diameter, which decreases when decreasing Lambda and which shows order of magnitude agreement with the micron-sized satellite bubbles observed experimentally.

  10. Phenomenology of break-up modes in contact free externally heated nanoparticle laden fuel droplets

    NASA Astrophysics Data System (ADS)

    Pathak, Binita; Basu, Saptarshi

    2016-12-01

    We study thermally induced atomization modes in contact free (acoustically levitated) nanoparticle laden fuel droplets. The initial droplet size, external heat supplied, and suspended particle concentration (wt. %) in droplets govern the stability criterion which ultimately determines the dominant mode of atomization. Pure fuel droplets exhibit two dominant modes of breakup namely primary and secondary. Primary modes are rather sporadic and normally do not involve shape oscillations. Secondary atomization however leads to severe shape deformations and catastrophic intense breakup of the droplets. The dominance of these modes has been quantified based on the external heat flux, dynamic variation of surface tension, acoustic pressure, and droplet size. Addition of particles alters the regimes of the primary and secondary atomization and introduces bubble induced boiling and bursting. We analyze this new mode of atomization and estimate the time scale of bubble growth up to the point of bursting using energy balance to determine the criterion suitable for parent droplet rupture. All the three different modes of breakup have been well identified in a regime map determined in terms of Weber number and the heat utilization rate which is defined as the energy utilized for transient heating, vaporization, and boiling in droplets.

  11. Breakup characteristics of aqueous droplet with surfactant in oil under direct current electric field.

    PubMed

    Luo, Xiaoming; Yan, Haipeng; Huang, Xin; Yang, Donghai; Wang, Jing; He, Limin

    2017-11-01

    The breakup process of aqueous droplet with surfactant suspended in oil under direct current (DC) electric field is investigated in this paper. The characteristics of the breakup process, stretching, necking and breakup, are discussed quantitatively with the electric capillary number Ca and the dimensionless surfactant concentration C(∗) which is the ratio of surfactant concentration to the critical micelle concentration. The results show that the presence of surfactant reduces the steady deformation of droplet and significantly decelerates the stretching process, resulting from the redistribution of surfactant molecules within the oil/water interface. The law of droplet stretching process when C(∗)≥1 indicates that the exchange of surfactant molecules between the bulk phase and the interface could not catch up with the increase of oil/water interfacial area. Ca and C(∗) count a great deal to the necking position and the daughter droplet size. The daughter droplet size decreases with the increase of surfactant concentration. These results provide a mechanistic framework to promote the electrocoalescence efficiency of oil/water emulsion and to the application of electric emulsification. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Role of Weber number in the primary breakup of liquid jets in crossflow

    NASA Astrophysics Data System (ADS)

    Pai, Madhusudan; Bermejo-Moreno, I.; Desjardins, Olivier; Pitsch, Heinz

    2009-11-01

    Atomization of liquid fuel controls the combustion efficiency and pollutant emissions from internal combustion engines and gas turbines. A liquid jet injected into a crossflow breaks up by developing liquid surface instabilities and deformations due to aerodynamic sources and liquid jet turbulence, among other causes. There is a pressing need to understand the origin and role of these instabilities in the breakup of a liquid jet. These instabilities can be accurately quantified in detailed numerical simulations of liquid jets. A spectrally-refined interface (SRI) tracking scheme for interface transport coupled to an accurate and robust Navier-Stokes/Ghost-fluid method gas-phase solver is employed to perform large-scale detailed numerical simulations of liquid jets in a laminar crossflow. The liquid Weber number controls the tendency of a liquid jet to break up, while the liquid Reynolds number controls the range of length scales in the liquid jet turbulence. The interplay and role of these phenomena in the primary breakup of liquid jets is quantified through a parametric study. Existing models for turbulent primary breakup of liquid jets in crossflow are reviewed based on the numerical results.

  13. Volcanic Versus Non-Volcanic Passive Margins: Two Different Ways to Break-up Continents

    NASA Astrophysics Data System (ADS)

    Geoffroy, L.; Burov, E. B.; Werner, P.; Unternehr, P.

    2014-12-01

    Volcanic passive margins (VPMs) are distinctive features of Larges Igneous Provinces. They characterize continental breakup associated with the extrusion and intrusion of large volumes of magma, predominantly mafic. In Large Igneous Provinces, regional fissural volcanism predates localized syn-magmatic break-up of the lithosphere, suggesting that mantle melting is a cause of continental break-up, not a consequence. Early melt covers as volcanic traps large cratonic or/and cratonic-edge continental areas. Crustal dilatation through dyking in the upper crust and magma underplating at Moho level is thought to occur massively during this early stage. Lithosphere extension leading to break-up and VPMs development is coeval with a 3D focusing of mantle melting, giving rise to VPMs. From a combination of deep seismic reflection profiles and onshore observations, we show that the mechanism of continental breakup at volcanic passive margins is very different from the one generally proposed for non-magmatic systems. Crustal extension and coeval extrusion of thick wedges of seaward-dipping basalts are accommodated by continentward-dipping detachment-faults at both conjugate margins. Those faults root on a deformed ductile crust whose composition seems partly magmatic. Our numerical modeling show that hardening of deep continental crust during the early magmatic stages provokes a divergent flow of the ductile lithosphere (mantle and lower crust) away from a central continental block which thins through advection with time. Magma-assisted crustal-scale faults dipping continentward root over this flowing material, isolating micro-continents which may be lost in the future oceanic domain. The structure and tectonic evolution of volcanic passive margins cannot therefore be compared to non-volcanic ones, where major detachment faults dip oceanward during the necking-stage and where mantle is finally exhumed during the mechanical breakup. Confusions may exist where ancient hyper

  14. Breakup of particle clumps on liquid surfaces

    NASA Astrophysics Data System (ADS)

    Gurupatham, S.; Hossain, M.; Dalal, B.; Fischer, I.; Singh, P.; Joseph, D.

    2011-11-01

    In this talk we describe the mechanism by which clumps of some powdered materials breakup and disperse on a liquid surface to form a monolayer of particles. We show that a clump breaks up because when particles on its outer periphery come in contact with the liquid surface they are pulled into the interface by the vertical component of capillary force overcoming the cohesive forces which keep them attached, and then these particles move away from the clump. In some cases, the clump itself is broken into smaller pieces and then these smaller pieces break apart by the aforementioned mechanism. The newly-adsorbed particles move away from the clump, and each other, because when particles are adsorbed on a liquid surface they cause a flow on the interface away from themselves. This flow may also cause particles newly-exposed on the outer periphery of the clump to break away. Since millimeter-sized clumps can breakup and spread on a liquid surface within a few seconds, their behavior appears to be similar to that of some liquid drops which can spontaneously disperse on solid surfaces.

  15. Breakup and atomization of a stretching crown.

    PubMed

    Roisman, Ilia V; Gambaryan-Roisman, Tatiana; Kyriopoulos, Olympia; Stephan, Peter; Tropea, Cam

    2007-08-01

    This study is devoted to experimental and theoretical investigation of splash produced by spray impact onto a smooth, rigid target under microgravity conditions. In particular, the formation of a film by the deposited liquid, the propagation and breakup of uprising sheets created by drop impacts, and the creation of secondary droplets have been observed. Three scenarios of splash have been identified during the experiments: (i) cusp formation and jetting due to the rim transverse instability, (ii) sheet destruction and the consequent rapid axisymmetric capillary breakup of a free rim, and (iii) the rim merging. Experimental data for various geometrical parameters of splash have been collected. Next, in order to predict the typical length scales of the interjet distance, a linear stability analysis of the rim in relation to transverse disturbances has been performed. The influence of the sheet stretching has been investigated and shown to be significant. The experimentally measured average values of the interjet distances agree well with the theoretical predictions. The sheet stretching is responsible for the appearance of the relatively long interjet distances.

  16. Breakup and atomization of a stretching crown

    NASA Astrophysics Data System (ADS)

    Roisman, Ilia V.; Gambaryan-Roisman, Tatiana; Kyriopoulos, Olympia; Stephan, Peter; Tropea, Cam

    2007-08-01

    This study is devoted to experimental and theoretical investigation of splash produced by spray impact onto a smooth, rigid target under microgravity conditions. In particular, the formation of a film by the deposited liquid, the propagation and breakup of uprising sheets created by drop impacts, and the creation of secondary droplets have been observed. Three scenarios of splash have been identified during the experiments: (i) cusp formation and jetting due to the rim transverse instability, (ii) sheet destruction and the consequent rapid axisymmetric capillary breakup of a free rim, and (iii) the rim merging. Experimental data for various geometrical parameters of splash have been collected. Next, in order to predict the typical length scales of the interjet distance, a linear stability analysis of the rim in relation to transverse disturbances has been performed. The influence of the sheet stretching has been investigated and shown to be significant. The experimentally measured average values of the interjet distances agree well with the theoretical predictions. The sheet stretching is responsible for the appearance of the relatively long interjet distances.

  17. Dynamics of jet breakup induced by perturbation

    NASA Astrophysics Data System (ADS)

    Shum, Ho Cheung; Li, Jingmei; Mak, Sze Yi

    2014-11-01

    We study the breakup of jet to form droplets, as induced by controlled perturbation, in a microchannel. Controlled mechanical perturbation is introduced to the tubing through which the jet phase is injected into the device, which is monitored under high-speed optical imaging. We measure the frequency of droplet formation and the sizes of the droplets as the frequency and amplitude of the perturbation is varied. Droplets can be induced to form at the perturbation frequency only above a critical frequency and amplitude. In this manner, the droplet size can be precisely controlled. The amplitude needed to induce breakup decreases as the interfacial tension of the system is lowered. Moreover, by selectively varying the wettability of the inner wall of the channel, double emulsion droplets can be generated in one step by applying large-amplitude perturbation of the jet phase. Our work demonstrates the potential of using controlled perturbation to generate droplets with tunable size and shapes, with implications on new designs of liquid dispensing nozzles.

  18. Bubble breakup phenomena in a venturi tube

    NASA Astrophysics Data System (ADS)

    Fujiwara, Akiko

    2005-11-01

    Microbubble has distinguished characteristics of large surface area to unit volume and small buoyancy, and it has advantages in many engineering fields. Recently microbubble generators with low energy and high performance are required to wide applications. In the present study, we propose one new effective technique to generate tiny bubbles with less than 200 μm diameter utilizing venturi tube under high void fraction condition. The objective of the present study is to elucidate the mechanism of bubble breakup phenomena in the venturi tube and to clarify the effects of parameters which are necessary to realize an optimum system experimentally. Experiment was conducted with void fraction of 4% and variation of liquid velocity from 9 to 26 m/s at the throat. Under low velocity condition, bubbles which were observed with a high speed camera parted gradually in a wide region. On the contrary under high velocity condition, bubbles expanded after passing through the throat and shrank rapidly. Since the speed of sound in gas-liquid system is extremely lower than that of single-phase flow, the bubble breakup phenomenon in the venturi tube is explained as the supersonic flow in a Laval nozzle. By rapid pressure recovery in diverging area, expanding bubbles collapse violently. The tiny bubbles are generated due to the surface instability of shrinking bubbles.

  19. Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup

    NASA Technical Reports Server (NTRS)

    Trinh, Huu P.; Chen, C. P.

    2005-01-01

    Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. This study aims to model the turbulence effect in the atomization process of a cylindrical liquid jet. Two widely used models, the Kelvin-Helmholtz (KH) instability of Reitz (blob model) and the Taylor-Analogy-Breakup (TAB) secondary droplet breakup by O Rourke et al, are further extended to include turbulence effects. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic scales and the initial flow conditions. For the secondary breakup, an additional turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. The drop size formed from this breakup regime is estimated based on the energy balance before and after the breakup occurrence. This paper describes theoretical development of the current models, called "T-blob" and "T-TAB", for primary and secondary breakup respectivety. Several assessment studies are also presented in this paper.

  20. Breakup channels for C12 triple-α continuum states

    NASA Astrophysics Data System (ADS)

    Diget, C. Aa.; Barker, F. C.; Borge, M. J. G.; Boutami, R.; Dendooven, P.; Eronen, T.; Fox, S. P.; Fulton, B. R.; Fynbo, H. O. U.; Huikari, J.; Hyldegaard, S.; Jeppesen, H. B.; Jokinen, A.; Jonson, B.; Kankainen, A.; Moore, I.; Nieminen, A.; Nyman, G.; Penttilä, H.; Pucknell, V. F. E.; Riisager, K.; Rinta-Antila, S.; Tengblad, O.; Wang, Y.; Wilhelmsen, K.; Äystö, J.

    2009-09-01

    The triple-α-particle breakup of states in the triple-α continuum of C12 has been investigated by way of coincident detection of all three α particles of the breakup. The states have been fed in the β decay of N12 and B12, and the α particles measured using a setup that covers all of the triple-α phase space. Contributions from the breakup through the Be8(0+) ground state as well as other channels—interpreted as breakup through excited energies in Be8—have been identified. Spins and parities of C12 triple-α continuum states are deduced from the measured phase-space distributions for breakup through Be8 above the ground state by comparison to a fully symmetrized sequential R-matrix description of the breakup. At around 10 MeV in C12, the breakup is found to be dominated by 0+ strength breaking up through the ghost of the Be8(0+) ground state with L=0 angular momentum between the first emitted α particle and the intermediate Be8 nucleus. For C12 energies above the 12.7 MeV 1+ state, however, L=2 breakup of a C12 2+ state through the Be8(2+) excited state dominates. Furthermore, the possibility of a 2+ excited state in the 9-12 MeV region of C12 is investigated.

  1. Breakup Effects on University Students' Perceived Academic Performance

    ERIC Educational Resources Information Center

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2012-01-01

    The Problem: Problems that might be expected to affect perceived academic performance were studied in a sample of 283 university students. Results: Breakup Distress Scale scores, less time since the breakup and no new relationship contributed to 16% of the variance on perceived academic performance. Variables that were related to academic…

  2. 24 CFR 982.315 - Family break-up.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Family break-up. 982.315 Section... SECTION 8 TENANT BASED ASSISTANCE: HOUSING CHOICE VOUCHER PROGRAM Leasing a Unit § 982.315 Family break-up. (a) The PHA has discretion to determine which members of an assisted family continue to receive...

  3. Breakup of free liquid jets influenced by external mechanical vibrations

    NASA Astrophysics Data System (ADS)

    Lad, V. N.; Murthy, Z. V. P.

    2017-02-01

    The breakup of liquid jets has been studied with various test liquids using externally imposed mechanical vibrations. Images of the jets were captured by a high speed camera up to the speed of 1000 frames per second, and analyzed to obtain the profile of the jet and breakup length. The dynamics of the jets have also been studied to understand the effects of additives—a surfactant and polymer—incorporating externally imposed mechanical vibrations. Different types of breakup modes have been explored with respect to the Weber number and Ohnesorge number. The introduction of mechanical vibrations have caused jet breakup with separated droplets at a comparatively lower Weber number. The region of jet breakup by neck formation at constant jet velocities also contracted due to mechanical vibrations.

  4. Artificial satellite break-ups. I - Soviet ocean surveillance satellites

    NASA Astrophysics Data System (ADS)

    Johnson, N. L.

    1983-02-01

    An analysis of the breakup patterns of eight Soviet Kosmos series ocean surveillance satellites is presented. It is noted that half of the 4700 objects presently detected in earth orbit are shards from destroyed objects. The locations and heading of each Soviet satellite breakup were tracked by the Naval Space Survelliance System. All events in the eastern hemisphere occurred in the ascending phase, while western hemisphere breakups happened in the descending phase. Gabbard (1971) diagrams of altitude vs. period are plotted as a function of a fragment's orbital period. The diagrams have been incorporated into a NASA computer program to backtrack along the fragments' paths to determine the pattern of the breakup. Although objects have been projected to have separated from some of the satellites before breakup, a discussion of the evidence leads to the conclusion that even though the satellites may have exploded no purpose can yet be discerned for the actions.

  5. Alignment fixture

    DOEpatents

    Bell, Grover C.; Gibson, O. Theodore

    1980-01-01

    A part alignment fixture is provided which may be used for precise variable lateral and tilt alignment relative to the fixture base of various shaped parts. The fixture may be used as a part holder for machining or inspection of parts or alignment of parts during assembly and the like. The fixture includes a precisely machined diameter disc-shaped hub adapted to receive the part to be aligned. The hub is nested in a guide plate which is adapted to carry two oppositely disposed pairs of positioning wedges so that the wedges may be reciprocatively positioned by means of respective micrometer screws. The sloping faces of the wedges contact the hub at respective quadrants of the hub periphery. The lateral position of the hub relative to the guide plate is adjusted by positioning the wedges with the associated micrometer screws. The tilt of the part is adjusted relative to a base plate, to which the guide plate is pivotally connected by means of a holding plate. Two pairs of oppositely disposed wedges are mounted for reciprocative lateral positioning by means of separate micrometer screws between flanges of the guide plate and the base plate. Once the wedges are positioned to achieve the proper tilt of the part or hub on which the part is mounted relative to the base plate, the fixture may be bolted to a machining, inspection, or assembly device.

  6. Electrohydrodynamic (EHD) stimulation of jet breakup

    NASA Technical Reports Server (NTRS)

    Crowley, J. M.

    1982-01-01

    Electrohydrodynamic (EHD) excitation of liquid jets offers an alternative to piezoelectric excitation without the complex frequency response caused by piezoelectric and mechanical resonances. In an EHD exciter, an electrode near the nozzle applies an alternating Coulomb force to the jet surface, generating a disturbance which grows until a drop breaks off downstream. This interaction is modelled quite well by a linear, long wave model of the jet together with a cylindrical electric field. The breakup length, measured on a 33 micrometer jet, agrees quite well with that predicted by the theory, and increases with the square of the applied voltage, as expected. In addition, the frequency response is very smooth, with pronounced nulls occurring only at frequencies related to the time which the jet spends inside the exciter.

  7. Impacts, tillites, and the breakup of Gondwanaland

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Marshall, John R.; Aggarwal, Hans

    1993-01-01

    Mathematical analysis demonstrates that substantial impact crater deposits should have been produced during the last 2 Gy of Earth's history. Textures of impact deposits are shown to resemble textures of tillites and diamictites of Precambrian and younger ages. The calculated thickness distribution for impact crater deposits produced during 2 Gy is similar to that of tillites and diamictites of 2 Ga or younger. We suggest, therefore, that some tillites/diamictites could be of impact origin. Extensive tillite/diamictite deposits predated continental flood basalts on the interior of Gondwanaland. Significantly, other investigators have already associated impact cratering with flood basalt volcanism and continental rifting. Thus, it is proposed that the breakup of Gondwanaland could have been initiated by crustal fracturing from impacts.

  8. Team formation and breakup in multiagent systems

    NASA Astrophysics Data System (ADS)

    Rao, Venkatesh Guru

    The goal of this dissertation is to pose and solve problems involving team formation and breakup in two specific multiagent domains: formation travel and space-based interferometric observatories. The methodology employed comprises elements drawn from control theory, scheduling theory and artificial intelligence (AI). The original contribution of the work comprises three elements. The first contribution, the partitioned state-space approach is a technique for formulating and solving co-ordinated motion problem using calculus of variations techniques. The approach is applied to obtain optimal two-agent formation travel trajectories on graphs. The second contribution is the class of MixTeam algorithms, a class of team dispatchers that extends classical dispatching by accommodating team formation and breakup and exploration/exploitation learning. The algorithms are applied to observation scheduling and constellation geometry design for interferometric space telescopes. The use of feedback control for team scheduling is also demonstrated with these algorithms. The third contribution is the analysis of the optimality properties of greedy, or myopic, decision-making for a simple class of team dispatching problems. This analysis represents a first step towards the complete analysis of complex team schedulers such as the MixTeam algorithms. The contributions represent an extension to the literature on team dynamics in control theory. The broad conclusions that emerge from this research are that greedy or myopic decision-making strategies for teams perform well when specific parameters in the domain are weakly affected by an agent's actions, and that intelligent systems require a closer integration of domain knowledge in decision-making functions.

  9. Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression.

    PubMed

    Keir, Derek; Belachew, M; Ebinger, C J; Kendall, J-M; Hammond, J O S; Stuart, G W; Ayele, A; Rowland, J V

    2011-01-01

    Rifting of the continents leading to plate rupture occurs by a combination of mechanical deformation and magma intrusion, yet the spatial and temporal scales over which these alternate mechanisms localize extensional strain remain controversial. Here we quantify anisotropy of the upper crust across the volcanically active Afar Triple Junction using shear-wave splitting from local earthquakes to evaluate the distribution and orientation of strain in a region of continental breakup. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The lack of rift-perpendicular anisotropy in the lithosphere, and corroborating geoscientific evidence of extension dominated by dyking, provide strong evidence that magma intrusion achieves the majority of plate opening in this zone of incipient plate rupture.

  10. Mapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression

    PubMed Central

    Keir, Derek; Belachew, M.; Ebinger, C.J.; Kendall, J.-M.; Hammond, J.O.S.; Stuart, G.W.; Ayele, A.; Rowland, J.V.

    2011-01-01

    Rifting of the continents leading to plate rupture occurs by a combination of mechanical deformation and magma intrusion, yet the spatial and temporal scales over which these alternate mechanisms localize extensional strain remain controversial. Here we quantify anisotropy of the upper crust across the volcanically active Afar Triple Junction using shear-wave splitting from local earthquakes to evaluate the distribution and orientation of strain in a region of continental breakup. The pattern of S-wave splitting in Afar is best explained by anisotropy from deformation-related structures, with the dramatic change in splitting parameters into the rift axis from the increased density of dyke-induced faulting combined with a contribution from oriented melt pockets near volcanic centres. The lack of rift-perpendicular anisotropy in the lithosphere, and corroborating geoscientific evidence of extension dominated by dyking, provide strong evidence that magma intrusion achieves the majority of plate opening in this zone of incipient plate rupture. PMID:21505441

  11. On the shear stabilization of capillary break-up of finite liquid bridges

    NASA Technical Reports Server (NTRS)

    Dijkstra, Henk A.

    1993-01-01

    In this paper we consider an isothermal finite liquid bridge under zero-gravity. A sinusoidal interfacial shear stress drives a nonparallel flow in the bridge. The linear stability of this flow to three-dimensional disturbances (which may deform the cylindrical gas-liquid interface) is determined numerically by solving an elliptic eigenvalue problem. Previous results on shear stabilization of capillary break-up of axially unbounded cylindrical interfaces containing a parallel flow are hereby extended to a nonparallel flow. The turning flow regions influence the stability significantly. However, for the particular cases considered, a small area in parameter space remains where the capillary instability is suppressed through interfacial shear. Second, non-axisymmetric oscillatory instabilities are found which originate from an interaction of the interface deformation and the basic flow. These instabilities may be the isothermal limit of the oscillatory instabilities observed in float-zone crystal growth.

  12. Dynamics of associative polymer solutions: Capillary break-up, jetting and rheology

    NASA Astrophysics Data System (ADS)

    Sharma, Vivek; Serdy, James G.; Threfall-Holmes, Phil; McKinley, Gareth H.

    2011-11-01

    Associative polymer solutions are used in extensively in the formulations for water-borne paints, food, inks, cosmetics, etc to control the rheology and processing behavior of multi-component dispersions. These complex dispersions are processed and used over a broad range of shear and extensional rates. Furthermore, the commercially relevant formulations use dilute solutions of associative polymers, which have low viscosity and short relaxation times, and hence their non-Newtonian response is not apparent in a conventional rheometer. In this talk, we explore several methods for systematically exploring the linear and nonlinear solution rheology of associative polymer dispersions, including: fractional model description of physical gelation, high frequency oscillatory tests at frequencies up to 10 kHz, microfluidic shear rheometry at deformation rates up to 1000000 /s and the influence of transient extensional rheology in the jet breakup. We show that high deformation rates can be obtained in jetting flows, and the growth and evolution of instability during jetting and break-up of these viscoelastic fluids shows the influence of both elasticity and extensibility.

  13. On the Mach number Effects on Droplet Breakup in Laminar Flow

    NASA Astrophysics Data System (ADS)

    Syahdan, Irfan Miladi

    A Volume of Fluid (VOF) multiphase numerical study was conducted using the commercial simulation software ANSYS Fluent to understand the effects of compressibility on droplet breakup in the laminar flow regime. A 2D axisymmetric domain which consists of four subdomains was used for the simulations. Validation of the setup and mesh was conducted by comparing to analytical shock tube equation, Engel's, and Boger et al.'s work. Two regimes of flows, subsonic and supersonic, were used and were obtained by selection of the operating pressure, velocity, density, dynamic viscosity, and temperature to keep the Reynolds, Weber, and Mach numbers at fixed values between cases. The Reynolds number was held constant at 100. Significant differences within the stripping breakup mode between the supersonic and subsonic cases for similar values of the Weber and Reynolds numbers were observed. The difference was observed in terms of droplet deformation, droplet deformed shape, and droplet lifetime. A Weber number effect is also observed to influence the droplet lifetime. Differences in the pressure distribution were found to drive the different degrees of vertical elongation while the viscous stress mainly acts to bend the droplet downstream. The pressure was found to be the major factor while viscous stress acts as the smaller factor in the physics during most of the deformation process, but viscous stress shows to be the major role at the beginning of the process. Comparison to the solid sphere case provided confirmation of the pressure distribution difference observed between supersonic and subsonic case was expected. Comparison to solid sphere also shows how droplet deformation itself plays a role in effecting the flow field.

  14. ALIGNING JIG

    DOEpatents

    Culver, J.S.; Tunnell, W.C.

    1958-08-01

    A jig or device is described for setting or aligning an opening in one member relative to another member or structure, with a predetermined offset, or it may be used for measuring the amount of offset with which the parts have previously been sct. This jig comprises two blocks rabbeted to each other, with means for securing thc upper block to the lower block. The upper block has fingers for contacting one of the members to be a1igmed, the lower block is designed to ride in grooves within the reference member, and calibration marks are provided to determine the amount of offset. This jig is specially designed to align the collimating slits of a mass spectrometer.

  15. Aerodynamic effects on primary breakup of turbulent liquids

    NASA Astrophysics Data System (ADS)

    Wu, P.-K.; Faeth, G. M.

    1993-01-01

    An experimental study of primary breakup of turbulent liquids is described, emphasizing liquid/gas density ratios less than 500 where aerodynamics effects are important. The experiments involved multiphase mixing layers along round water jets (3.6 and 6.2 mm dia.) injected at various velocities into still helium, air and Freon 12 at pressures of 1 and 2 atm. with fully-developed turbulent pipe flow at the jet exit. Pulsed shadowgraph photography and holography were used to find conditions at the onset of breakup as well as drop properties as a function of distance from the jet exit. Two main aerodynamic effects were observed, as follows: (1) enhanced primary breakup near the onset of breakup, and (2) merged primary and secondary breakup when the Rayleigh breakup times of ligaments formed by turbulent fluctuations were longer than the secondary breakup times of similar sized drops. The predictions of phenomenological theories based on these ideas were in good agreement with the measurements.

  16. Signatures of Pseudo-breakup, Breakup of a Full Substorm Onset, and Poleward Border Intensifications Compared.

    NASA Astrophysics Data System (ADS)

    Voronkov, I.; Donovan, E. F.; Samson, J. C.

    2001-12-01

    For several exceptional events, we use ground-based and in-situ data to compare the ionospheric, geostationary, and mid-tail signatures of the pseudo-breakup, breakup, and poleward border intensifications (PBIs). In doing so, we utilize CANOPUS magnetometer and multi-wavelength photometer and All-sky imager data, as well as field measurements provided by the GOES 8, GOES 9, and Geotail spacecraft. We have identified a set of distinguishable signatures of each process. Pseudo-breakup consists of two distinct stages: near-linear arc intensification corresponding to the ``explosive growth phase" at geostationary orbit, and poleward vortex expansion that starts simultaneously with explosive onset of short period pulsations (Pi1, Pi2) and dipolarization observed at geostationary orbit. It can be accompanied by local perturbations of the equatorward part of the electron precipitation region and by formation of the substorm-like local current system but neither by optical signatures of the lobe flux reconnection nor by perturbations in the mid-tail. It typically saturates near the equatorward border of the electron precipitation region producing a mushroom-like auroral structure. Breakup starts with the same two-stage initial scenario of the arc intensification and vortex evolution but it rapidly expands poleward and is accompanied by optical signatures of reconnection onset, namely the aurora develops into a cell-like structure of the size compatible with the whole auroral zone width. This occurs at the time when mid-tail disruption signatures are observed. Full onset launches a second, more global, larger Pi2 burst. Finally, we show an example of PBIs observed as long period pulses of electron precipitation at the poleward border of auroral region, followed by the high-latitude proton aurora. The commencement of PBI coincided with bursty bulk flows and pulses of plasma energization in the mid-tail. Observed features are discussed with respect to recent ideas claiming

  17. Image alignment

    DOEpatents

    Dowell, Larry Jonathan

    2014-04-22

    Disclosed is a method and device for aligning at least two digital images. An embodiment may use frequency-domain transforms of small tiles created from each image to identify substantially similar, "distinguishing" features within each of the images, and then align the images together based on the location of the distinguishing features. To accomplish this, an embodiment may create equal sized tile sub-images for each image. A "key" for each tile may be created by performing a frequency-domain transform calculation on each tile. A information-distance difference between each possible pair of tiles on each image may be calculated to identify distinguishing features. From analysis of the information-distance differences of the pairs of tiles, a subset of tiles with high discrimination metrics in relation to other tiles may be located for each image. The subset of distinguishing tiles for each image may then be compared to locate tiles with substantially similar keys and/or information-distance metrics to other tiles of other images. Once similar tiles are located for each image, the images may be aligned in relation to the identified similar tiles.

  18. Trends of ice breakup date in south-central Ontario

    NASA Astrophysics Data System (ADS)

    Fu, Congsheng; Yao, Huaxia

    2015-09-01

    Large-scale ice phenology studies have revealed overall patterns of later freeze, earlier breakup, and shorter duration of ice in the Northern Hemisphere. However, there have been few studies regarding the trends, including their spatial patterns, in ice phenology for individual waterbodies on a local or small regional scale, although the coherence of ice phenology has been shown to decline rapidly in the first few hundred kilometers. In this study, we extracted trends, analyzed affecting factors, and investigated relevant spatial patterns for ice breakup date time series at 10 locations with record length ≥90 years in south-central Ontario, Canada. Wavelet methods, including the multiresolution analysis (MRA) method for nonlinear trend extraction and the wavelet coherence (WTC) method for identifying the teleconnections between large-scale climate modes and ice breakup date, are proved to be effective in ice phenology analysis. Using MRA method, the overall trend of ice breakup date time series (1905-1991) varied from earlier ice breakup to later ice breakup, then to earlier breakup again from south to north in south-central Ontario. Ice breakup date is closely correlated with air temperature during certain winter/spring months, as well as the last day with snow on the ground and number of snow-on-ground days. The influences of solar activity and Pacific North American on ice breakup were comparatively uniform across south-central Ontario, while those of El Niño-Southern Oscillation, North Atlantic Oscillation, and Arctic Oscillation on ice phenology changed with distance of 50-100 km in the north-south direction.

  19. New description of four-body break-up reaction

    SciTech Connect

    Matsumoto, T.; Kato, K.; Yahiro, M.

    2011-06-28

    We present a new method of smoothing discrete breakup cross sections calculated by the method of continuum-discretized coupled-channels. In the four-body breakup reaction of {sup 12}C({sup 6}He, nn{sup 4}He) at E{sub in} = 229.8 MeV, the continuous breakup cross section is evaluated as a function of the excitation energy of {sup 6}He. Convergence of the cross section with respect to extending the modelspace is also confirmed.

  20. Automatic assessment of tear film break-up dynamics.

    PubMed

    Ramos, L; Barreira, N; Pena-Verdeal, H; Giráldez, M J

    2014-01-01

    Dry eye syndrome is a common disorder of the tear film which affects a remarkable percentage of the population. The Break-Up Time (BUT) is a clinical test used for the diagnosis of this disease, which computes the time the first tear film break-up appears. This work describes a fully automatic methodology to compute the BUT measurement and evaluate the break-up dynamics until the final blink. This analysis provides useful additional information for the assessment of tear film stability.

  1. The oil body formation and breakup in the compound vortex

    NASA Astrophysics Data System (ADS)

    Chaplina, T. O.; Stepanova, E. V.

    2012-04-01

    The flows in the Ocean and Atmosphere combine different types of motion: streams, jets, wakes, vortices and waves. When flows transport solid bodies or immiscible admixtures picturesque flow patterns are revealed and indicated the type of flow. Different spiral patterns visualize vortex flow structure. In experiments is studied the transport of finite volumes of immiscible admixture introduced on the free surface of water drawn into the vortex motion in the vertical cylindrical container. The basic medium was tap water, preliminary degasified to make the visualization less difficult. The fixed volume of immiscible admixture (castor or sunflower oil) is introduced on the quiescent free surface of water inside the cylindrical container. The generation of compound vortex in the cylindrical container started after all the disturbances caused by deposition of the oil volume are damped. In compound vortex the flow oil patch with smooth boundary placed onto free surface is transformed into a set of spiral arms and separate drops contacting with the central oil volume. The droplets are separated from the central spot and slowly travel towards the container sidewall. With time, the spot is transformed into pronounced spiral arms. The most part of oil under the influence of vortex flow is gathered into the central volume contacting with the free surface. This volume is called "the oil body". On the lower frequencies of disk rotation and respectively slow flow gyration the oil body has smooth boundaries with water and air. The growth of disk rotation frequency leads to more pronounced deformation of the contact surface between liquid and air, the boundary of the oil body and water then is covered by small pimples. At the further increase of disk rotation frequency the oil body comes to the breakup, the water-oil boundary become irregular and on the lowest part of the oil body the analog of foam appears (the water-oil emulsion). The work is supported by Ministry of Education

  2. The Spectrum of Satellite Breakup and Fragmentation

    NASA Astrophysics Data System (ADS)

    Finkleman, D.

    The objective of this paper is to expose the spectrum of satellite breakup physics and is implications for debris production and observables. Satellite response to the debris environment generally emphasizes small scale hypervelocity impact or the interaction of intense, coherent radiation with satellite surfaces or internals. There are empirical correlations of fragment size distributions based on arena tests and extremely rare observations of breakups in space. Klinkrad describes well research on material response to hypervelocity impact such as the ballistic limit for various materials and shielding walls. Smirnov, et. al., report well the phenomenology of breakups under the influence of nonuniform internal loading of monolithic bodies, such as pressurized tanks. They set forth the transformation of elastic energy into fragment kinetic energy. They establish a sound physical framework for bounding the number of fragments. We took advantage of these works in our previous papers. There is not much research into the response of nonuniform structures to hypervelocity collisions with similarly massive and complex objects. This work generally employs complex hydrodynamic and finite element computation that is not well suited to real time, operational assessment of the consequences of such encounters. We hope to diminish the void between the extremes of microscopic impact and complex hydrocodes. Our previous reports employed the framework established by Chobotov and Spencer, fundamentally equilibrium, Newtonian approach. We now explore the spectrum of interactions and debris evolutions possible with realistic combinations of these theories. The spectrum encompasses Newtonian, semi-elastic energy and momentum transfer through little or no momentum exchange and from virtually all of the mass of the colliders being involved through fractional mass involvement. We observe that the more Newtonian outcomes do not agree well with sparse observations of the few collisions that

  3. Transient deformation in the Asal-Ghoubbet Rift (Djibouti) since the 1978 diking event: Is deformation controlled by magma supply rates?

    NASA Astrophysics Data System (ADS)

    Smittarello, D.; Grandin, R.; De Chabalier, J.-B.; Doubre, C.; Deprez, A.; Masson, F.; Socquet, A.; Saad, I. A.

    2016-08-01

    The Asal-Ghoubbet Rift (AG Rift) in Djibouti lies in the subaerial continuation of the Aden ridge system, thereby constituting a unique location to study rifting processes and mechanisms involved in continental breakup and oceanic spreading. Continually upgraded and expanded geodetic technology has been used to record the 1978 Asal rifting event and postdiking deformation. In light of recent results obtained for the Manda Hararo-Dabbahu rifting event (2005-2010), we propose that the horizontal and vertical geodetic data can be modeled with a double source, involving a dike-like inflation component aligned along the rift axis and a spherical pressure source located at midsegment below the Fieale caldera. By revisiting the codiking data, we propose that the reservoir below Fieale could have fed, at least partially, the 1978 injection and the contemporaneous Ardoukôba eruption and potentially induced local subsidence due to magma draining out of the central reservoir. As an alternative to previously proposed viscoelastic relaxation models, we reinterpret postdiking observations using a purely elastic rheology. We determine the relative contribution of a midsegment reservoir inflation and a dike-like opening component, together with their respective time evolutions. Our results suggest that interactions between steadily accumulating tectonic strain and temporal variations in melt supply to the shallow magma plumbing system below the AG Rift may entirely explain the geodetic observations and that viscoelastic deformation processes played a minor role in the 30 years following the 1978 rifting event.

  4. MUSE alignment onto VLT

    NASA Astrophysics Data System (ADS)

    Laurent, Florence; Renault, Edgard; Boudon, Didier; Caillier, Patrick; Daguisé, Eric; Dupuy, Christophe; Jarno, Aurélien; Lizon, Jean-Louis; Migniau, Jean-Emmanuel; Nicklas, Harald; Piqueras, Laure

    2014-07-01

    MUSE (Multi Unit Spectroscopic Explorer) is a second generation Very Large Telescope (VLT) integral field spectrograph developed for the European Southern Observatory (ESO). It combines a 1' x 1' field of view sampled at 0.2 arcsec for its Wide Field Mode (WFM) and a 7.5"x7.5" field of view for its Narrow Field Mode (NFM). Both modes will operate with the improved spatial resolution provided by GALACSI (Ground Atmospheric Layer Adaptive Optics for Spectroscopic Imaging), that will use the VLT deformable secondary mirror and 4 Laser Guide Stars (LGS) foreseen in 2015. MUSE operates in the visible wavelength range (0.465-0.93 μm). A consortium of seven institutes is currently commissioning MUSE in the Very Large Telescope for the Preliminary Acceptance in Chile, scheduled for September, 2014. MUSE is composed of several subsystems which are under the responsibility of each institute. The Fore Optics derotates and anamorphoses the image at the focal plane. A Splitting and Relay Optics feed the 24 identical Integral Field Units (IFU), that are mounted within a large monolithic structure. Each IFU incorporates an image slicer, a fully refractive spectrograph with VPH-grating and a detector system connected to a global vacuum and cryogenic system. During 2012 and 2013, all MUSE subsystems were integrated, aligned and tested to the P.I. institute at Lyon. After successful PAE in September 2013, MUSE instrument was shipped to the Very Large Telescope in Chile where that was aligned and tested in ESO integration hall at Paranal. After, MUSE was directly transported, fully aligned and without any optomechanical dismounting, onto VLT telescope where the first light was overcame the 7th of February, 2014. This paper describes the alignment procedure of the whole MUSE instrument with respect to the Very Large Telescope (VLT). It describes how 6 tons could be move with accuracy better than 0.025mm and less than 0.25 arcmin in order to reach alignment requirements. The success

  5. New description of the four-body breakup reaction

    SciTech Connect

    Matsumoto, Takuma; Kato, Kiyoshi; Yahiro, Masanobu

    2010-11-15

    We present a novel method of smoothing discrete breakup cross sections calculated by the method of continuum-discretized coupled channels. The smoothing method based on the complex scaling method is tested with success for a {sup 58}Ni(d,pn) reaction at 80 MeV as an example of three-body breakup reactions and applied to a {sup 12}C({sup 6}He,nn {sup 4}He) reaction at 229.8 MeV as an example of four-body breakup reactions. Fast convergence of the breakup cross section with respect to extending the model space is confirmed. The method is also applied to {sup 12}C({sup 6}He,nn {sup 4}He) and {sup 208}Pb({sup 6}He,nn {sup 4}He) reactions at 240 MeV/A and compared with the experimental data.

  6. Using electric current to surpass the microstructure breakup limit

    NASA Astrophysics Data System (ADS)

    Qin, Rongshan

    2017-01-01

    The elongated droplets and grains can break up into smaller ones. This process is driven by the interfacial free energy minimization, which gives rise to a breakup limit. We demonstrated in this work that the breakup limit can be overpassed drastically by using electric current to interfere. Electric current free energy is dependent on the microstructure configuration. The breakup causes the electric current free energy to reduce in some cases. This compensates the increment of interfacial free energy during breaking up and enables the processing to achieve finer microstructure. With engineering practical electric current parameters, our calculation revealed a significant increment of the obtainable number of particles, showing electric current a powerful microstructure refinement technology. The calculation is validated by our experiments on the breakup of Fe3C-plates in Fe matrix. Furthermore, there is a parameter range that electric current can drive spherical particles to split into smaller ones.

  7. {sup 17}F breakup reactions: a touchstone for indirect measurements

    SciTech Connect

    De Napoli, M.; Raciti, G.; Sfienti, C.; Capel, P.; Baye, D.; Descouvemont, P.; Sparenberg, J.-M.; Giacoppo, F.; Rapisarda, E.; Cardella, G.; Mazzocchi, C.

    2011-10-28

    An exclusive study of {sup 17}F breakup reactions has been performed at the FRIBs facility of the Laboratori Nazionali del Sud in Catania (Italy). The experiment has been performed with the aim of testing the accuracy of the Coulomb-breakup indirect technique used to infer radiative-capture cross sections at low energies. This technique has been used in the {sup 7}Be(p,{gamma}){sup 8}B case, but has never been tested. By measuring the breakup of {sup 17}F into {sup 16}O+p, and comparing the inferred cross section for {sup 16}O(p,{gamma}){sup 17}F to direct precise measurements, the influence of E2 transitions and higher-order effects, that are predicted to be significant in Coulomb-breakup reactions, can be evaluated. The first results and preliminary model comparison are reported.

  8. Investigation of the intermediate-energy deuteron breakup reaction

    SciTech Connect

    Divadeenam, M.; Ward, T.E.; Mustafa, M.G.; Udagawa, T.; Tamura, T.

    1989-01-01

    The Udagawa-Tamura formalism is employed to calculate the proton singles both in the bound and unbound regions. Both the Elastic-Breakup (EB) and the Breakup-Fusion (BF) processes are considered to calculate the doubly-differential cross section for light and intermediate mass nuclei. The calculated spectra for 25 and 56 MeV deuterons reproduce the experimental spectra very well except for the spectra at large angle and at low energies, of the outgoing particle. Contributions due to precompound and evaporation processes are estimated to supplement the spectral results based on the Elastic-Breakup and Breakup-Fusion mechanisms. An extension of the model calculations to higher deuteron energies is being made to test the (EB + BF) model limitations. 5 refs., 1 fig.

  9. Using electric current to surpass the microstructure breakup limit

    PubMed Central

    Qin, Rongshan

    2017-01-01

    The elongated droplets and grains can break up into smaller ones. This process is driven by the interfacial free energy minimization, which gives rise to a breakup limit. We demonstrated in this work that the breakup limit can be overpassed drastically by using electric current to interfere. Electric current free energy is dependent on the microstructure configuration. The breakup causes the electric current free energy to reduce in some cases. This compensates the increment of interfacial free energy during breaking up and enables the processing to achieve finer microstructure. With engineering practical electric current parameters, our calculation revealed a significant increment of the obtainable number of particles, showing electric current a powerful microstructure refinement technology. The calculation is validated by our experiments on the breakup of Fe3C-plates in Fe matrix. Furthermore, there is a parameter range that electric current can drive spherical particles to split into smaller ones. PMID:28120919

  10. Self-similar breakup of near-inviscid liquids

    NASA Astrophysics Data System (ADS)

    Castrejon-Pita, Alfonso A.; Castrejon-Pita, J. Rafael; Lister, John R.; Hinch, E. John; Hutchings, Ian M.

    2012-11-01

    Experimental results are presented for the final stages of drop pinch-off and ligament breakup for different initial conditions. Water and ethanol were used as working fluids. High-speed imaging and image analysis were utilized in order to determine the contraction rate of the thinning neck and the shape of the liquid thread just before the breakup. Our results show that the geometry of the breakup of near-inviscid fluids is self-similar in the domain of simple dripping. We also demonstrate that, independently of the initial conditions, the necking of these liquids scales with τ 2 / 3, asymptotically giving a unique breakup angle of 18 . 0 +/- 0 .4° . Both observations are in complete agreement with previous theoretical predictions. The angle converges towards self similarity like τ 1 / 2, also as predicted. Project supported by the EPSRC-UK (EP/G029458/1 and EP/H018913/1) and Cambridge-KACST.

  11. ISS Update: ATV-3 ReEntry Breakup Recorder

    NASA Image and Video Library

    ISS Update Commentator Pat Ryan talks with Dr. William Ailor, Principal Investigator for the ReEntry Breakup Recorder (REBR) for The Aerospace Corporation. Ailor talks about capturing data as Europ...

  12. Breakup of 87 MeV [sup 11]B

    SciTech Connect

    Wolfs, F.L.H.; White, C.A.; Bryan, D.C.; Freeman, C.G.; Herrick, D.M.; Kurz, K.L.; Mathews, D.H.; Perera, P.A.A.; Zanni, M.T. )

    1994-05-01

    A segmented focal plane detector has been used to study the breakup of 87 MeV [sup 11]B ions incident on a [sup 12]C target into [sup 4]He and [sup 7]Li fragments at relative energies between 0 and 4 MeV. The relative energy spectra are dominated by sequential breakup of the 9.28 MeV, 10.26+10.33 MeV, and 10.60 MeV excited states in [sup 11]B. The measured breakup yields decrease with increasing center-of-mass scattering angle, consistent with predictions made using single-step inelastic distorted wave Born approximation calculations. Applications of this technique to study the breakup of [sup 16]O at low relative energies will be discussed.

  13. Using electric current to surpass the microstructure breakup limit.

    PubMed

    Qin, Rongshan

    2017-01-25

    The elongated droplets and grains can break up into smaller ones. This process is driven by the interfacial free energy minimization, which gives rise to a breakup limit. We demonstrated in this work that the breakup limit can be overpassed drastically by using electric current to interfere. Electric current free energy is dependent on the microstructure configuration. The breakup causes the electric current free energy to reduce in some cases. This compensates the increment of interfacial free energy during breaking up and enables the processing to achieve finer microstructure. With engineering practical electric current parameters, our calculation revealed a significant increment of the obtainable number of particles, showing electric current a powerful microstructure refinement technology. The calculation is validated by our experiments on the breakup of Fe3C-plates in Fe matrix. Furthermore, there is a parameter range that electric current can drive spherical particles to split into smaller ones.

  14. Analytical Description of the Breakup of Liquid Jets in Air

    DTIC Science & Technology

    1993-07-01

    Papageorgiou and Orellana (1993), referred to as PO, to describe breakup of jets of one fluid into another with different density, with or without...as a small parameter. As noted by Papageorgiou and Orellana , such an ansatz can be applied to flows which have initial conditions characterized by a...formation in capillary jet breakup. Phys. Fluids A, 2, 1141-1144. " Papageorgiou, D.T. and Orellana , 0. 1993 Pinching solutions of slender

  15. Aggregate breakup in a contracting nozzle.

    PubMed

    Soos, Miroslav; Ehrl, Lyonel; Bäbler, Matthäus U; Morbidelli, Massimo

    2010-01-05

    The breakup of dense aggregates in an extensional flow was investigated experimentally. The flow was realized by pumping the suspension containing the aggregates through a contracting nozzle. Variation of the cluster mass distribution during the breakage process was measured by small-angle light scattering. Because of the large size of primary particles and the dense aggregate structure image analysis was used to determine the shape and structure of the produced fragments. It was found, that neither aggregate structure, characterized by a fractal dimension d(f) = 2.7, nor shape, characterized by an average aspect ratio equal to 1.5, was affected by breakage. Several passes through the nozzle were required to reach the steady state. This is explained by the radial variation of the hydrodynamic stresses at the nozzle entrance, characterized through computational fluid dynamics, which implies that only the fraction of aggregates whose strength is smaller than the local hydrodynamic stress is broken during one pass through the nozzle. Scaling of the steady-state aggregate size as a function of the hydrodynamic stress was used to determine the aggregate strength.

  16. On the Eddy Break-Up coefficient

    SciTech Connect

    Brizuela, E.A.; Bilger, R.W.

    1996-01-01

    Advanced combustion models for turbulent reactive flow are still not at a stage where they are useful for engineering calculations of practical systems such as gas turbine combustors. State-of-the-art methods still use the Eddy Break-Up (EBU) model to give the fast chemistry limit to the reaction rate with a global kinetics formula being used to estimate the kinetically limited rates. While there must continue to be basic reservations about the general correctness of the EBU approach, it has recently been shown that the EBU limit does have a basis in theory for the nonpremixed case. The theoretical result of Bilger for the mixing-limited reaction rate shows that it is proportional to the probability density of the mixture being at stoichiometric. The EBU model, however, takes it as being proportional to the mass fraction of the deficient reactant, but this is in turn a property of the mixture fraction pdf (probability density function) under fast chemistry conditions. The theoretical result can be used to evaluate the correct value of the EBU coefficient, which is usually taken as a constant but with quite widely varying values. In this paper the authors evaluate this theoretical value for the EBU coefficient using two commonly adopted forms of the pdf. Recommendations are made with regard to the best values to use in practice.

  17. Timing and geometry of early Gondwana breakup

    NASA Astrophysics Data System (ADS)

    Jokat, Wilfried; Boebel, Tobias; KöNig, Matthias; Meyer, Uwe

    2003-09-01

    The Mesozoic opening history of the Southern Ocean between South America, Africa, and Antarctica is one of the largest gaps in knowledge on the evolution of this region. Competing geodynamic models were published during the last two decades to explain the geophysical and geological observations. Here we report on aeromagnetic data collected along the East Antarctic coast during five seasons. These data provide new constraints on the timing and geometry of the early Gondwana breakup. In the Riiser-Larsen Sea/Mozambique Basin, the first oceanic crust between Africa and Antarctica formed around 155 Ma. In the west the Weddell Rift propagated from west to east with a velocity of 63 km/Myr between chrons M19N and M17N. At chron M14N, South America and Africa finally were split off the Antarctic continent. Stretching in the area of the South Atlantic started at the latest from 155 Myr onward. The different spreading velocities and directions of South America and Africa created at chron M9N the first oceanic crust in the South Atlantic. A new model indicates that the Karoo and Dronning Maud Land magmatism occurred well before any new ocean floor was created and therefore the first formation of new oceanic crust cannot directly be related to a plume interaction.

  18. Calibration of shaft alignment instruments

    NASA Astrophysics Data System (ADS)

    Hemming, Bjorn

    1998-09-01

    Correct shaft alignment is vital for most rotating machines. Several shaft alignment instruments, ranging form dial indicator based to laser based, are commercially available. At VTT Manufacturing Technology a device for calibration of shaft alignment instruments was developed during 1997. A feature of the developed device is the similarity to the typical use of shaft alignment instruments i.e. the rotation of two shafts during the calibration. The benefit of the rotation is that all errors of the shaft alignment instrument, for example the deformations of the suspension bars, are included. However, the rotation increases significantly the uncertainty of calibration because of errors in the suspension of the shafts in the developed device for calibration of shaft alignment instruments. Without rotation the uncertainty of calibration is 0.001 mm for the parallel offset scale and 0,003 mm/m for the angular scale. With rotation the uncertainty of calibration is 0.002 mm for the scale and 0.004 mm/m for the angular scale.

  19. Multiphase simulation of liquid jet breakup using smoothed particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Pourabdian, Majid; Omidvar, Pourya; Morad, Mohammad Reza

    This paper deals with numerical modeling of two-phase liquid jet breakup using the smoothed particle hydrodynamics (SPH) method. Simulation of multiphase flows involving fluids with a high-density ratio causes large pressure gradients at the interface and subsequently divergence of numerical solutions. A modified procedure extended by Monaghan and Rafiee is employed to stabilize the sharp interface between the fluids. Various test cases such as Rayleigh-Taylor instability, two-phase still water and air bubble rising in water have been conducted, by which the capability of accurately capturing the physics of multiphase flows is verified. The results of these simulations are in a good agreement with analytical and previous numerical solutions. Finally, the simulation of the breakup process of liquid jet into surrounding air is accomplished. The whole numerical solutions are accomplished for both Wendland and cubic spline kernel functions and Wendland kernel function gave more accurate results. Length of liquid breakup in Rayleigh regime is calculated for various flow conditions such as different Reynolds and Weber numbers. The results of breakup length demonstrate in satisfactory agreement with the experimental correlation. Finally, impinging distance and breakup length of a simple multijet setup are analyzed. The two-jet multijet has a longer breakup length than a three-jet one.

  20. Coulomb and nuclear effects in breakup and reaction cross sections

    NASA Astrophysics Data System (ADS)

    Descouvemont, P.; Canto, L. F.; Hussein, M. S.

    2017-01-01

    We use a three-body continuum discretized coupled channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li+208Pb . For breakup, we investigate various aspects, such as the role of the α +t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the Coulomb and nuclear breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest a third method which could be efficiently used to address convergence problems at large angular momentum. For reaction cross sections, interference effects are smaller, and the nuclear contribution is dominant above the Coulomb barrier. We also draw attention to different definitions of the reaction cross section which exist in the literature and which may induce small, but significant, differences in the numerical values.

  1. Breakup of rivulet falling over an inclined plate

    NASA Astrophysics Data System (ADS)

    Singh, Rajesh; Galvin, Janine

    2016-11-01

    The multiscale modeling of solvent absorption in a structured packing is a complex problem. The local hydrodynamics in the packing, specifically existing flow regimes, is a key factor for overall efficiency. A single packing unit is made of corrugated sheets arranged perpendicularly to each other. In this effort, breakup of rivulet over an inclined plate is examined, which might be helpful to explain some fundamental aspects of this system. Rivulet breakup is a complex phenomenon dictated by many factors such as solvent physical properties, contact angle (γ) , inertia, plate inclination angle (θ) , etc. The multiphase flow simulations using the volume of fluid method were conducted considering these factors. Decreasing solvent flow rate results in the transition of flow regimes from a film to a rivulet and then to a droplet. Demarcation between a stable and an unstable flow regime that leads to breakup is presented in terms of the critical Weber number (Wecr) . Values of Weber number below Wecr correspond to breakup behavior and above to a stable rivulet. The impact of solvent properties is presented by the Kapitza number (Ka), which only depends on fluid properties. Variation of Wecr with Ka shows two trends depending on the Ka value of the solvent. Solvents with low Ka show a linear variation of Wecr with Ka whereas those with high Ka show a quadratic variation. The effect of plate inclination on the rivulet breakup reveals that Wecr decreases with increased θ value. In addition, higher values of γ promote breakup.

  2. The breakup of (16)O and its astrophysical implications

    NASA Astrophysics Data System (ADS)

    Bryan, Diane Carol

    1998-07-01

    The feasibility of using the breakup of 16O to obtain information about the 12C(/alpha,/gamma)16O radiative capture reaction has been studied in a series of experiments performed at the Nuclear Structure Research Laboratory at the University of Rochester. The 16O breakup fragments-12C and 4He-were identified using a new focal-plane detector capable of identifying these fragments down to a relative energy of 50 keV. The relative energy spectra obtained from 16O breakup on a 58Ni target are dominated by sequential breakup from 9.85 MeV, and 10.36 MeV excited states in 16O. There is also some evidence of breakup at relative energies below 1 MeV. Interpretation of this low energy yield in terms of E2 Coulomb excitation leads to a value of SE2=346 keV b at Erel=0.828 MeV after making a correction for the contribution due to nuclear breakup. This suggests that the rate of the 12C(/alpha,/gamma)16O reaction at astrophysical energies is much higher than is presently accepted, which would have an enormous impact on stellar nucleosynthesis.

  3. Coalescence, torus formation and breakup of sedimenting drops: experiments and computer simulations

    NASA Astrophysics Data System (ADS)

    Machu, Gunther; Meile, Walter; Nitsche, Ludwig C.; Schaflinger, Uwe

    2001-11-01

    The motion and shape evolution of viscous drops made from a dilute suspension of tiny, spherical glass beads sedimenting in an otherwise quiescent liquid is investigated both experimentally and theoretically for conditions of low Reynolds number. In the (presumed) absence of any significant interfacial tension, the Bond number [script B] = ([Delta][rho])gR2/[sigma] is effectively infinite. The key stages of deformation of single drops and pairs of interacting drops are identified. Of particular interest are (i) the coalescence of two trailing drops, (ii) the subsequent formation of a torus, and (iii) the breakup of the torus into two or more droplets in a repeating cascade. To overcome limitations of the boundary-integral method in tracking highly deformed interfaces and coalescing and dividing drops, we develop a formal analogy between drops of homogeneous liquid and a dilute, uniformly distributed swarm of sedimenting particles, for which only the 1/r far-field hydrodynamic interactions are important. Simple, robust numerical simulations using only swarms of Stokeslets reproduce the main phenomena observed in the classical experiments and in our flow-visualization studies. Detailed particle image velocimetry (PIV) for axisymmetric configurations enable a mechanistic analysis and confirm the theoretical results. We expose the crucial importance of the initial condition why a single spherical drop does not deform substantially, but a pair of spherical drops, or a bell-shaped drop similar to what is actually formed in the laboratory, does undergo the torus/breakup transformation. The extreme sensitivity of the streamlines to the shape of the ring-like swarm explains why the ring that initially forms in the experiments does not behave like the slender open torus analysed asymptotically by Kojima, Hinch & Acrivos (1984). Essentially all of the phenomena described above can be explained within the realm of Stokes flow, without resort to interfacial tension or inertial

  4. IUS prerelease alignment

    NASA Technical Reports Server (NTRS)

    Evans, F. A.

    1978-01-01

    Space shuttle orbiter/IUS alignment transfer was evaluated. Although the orbiter alignment accuracy was originally believed to be the major contributor to the overall alignment transfer error, it was shown that orbiter alignment accuracy is not a factor affecting IUS alignment accuracy, if certain procedures are followed. Results are reported of alignment transfer accuracy analysis.

  5. Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup

    NASA Technical Reports Server (NTRS)

    Trinh, Huu; Chen, C. P.

    2004-01-01

    Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. For certain flow regimes, it has been observed that the liquid jet surface is highly turbulent. This turbulence characteristic plays a key role on the breakup of the liquid jet near to the injector exit. Other experiments also showed that the breakup length of the liquid core is sharply shortened as the liquid jet is changed from the laminar to the turbulent flow conditions. In the numerical and physical modeling arena, most of commonly used atomization models do not include the turbulence effect. Limited attempts have been made in modeling the turbulence phenomena on the liquid jet disintegration. The subject correlation and models treat the turbulence either as an only source or a primary driver in the breakup process. This study aims to model the turbulence effect in the atomization process of a cylindrical liquid jet. In the course of this study, two widely used models, Reitz's primary atomization (blob) and Taylor-Analogy-Break (TAB) secondary droplet breakup by O Rourke et al. are examined. Additional terms are derived and implemented appropriately into these two models to account for the turbulence effect on the atomization process. Since this enhancement effort is based on a framework of the two existing atomization models, it is appropriate to denote the two present models as T-blob and T-TAB for the primary and secondary atomization predictions, respectively. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic time scales and the initial flow conditions. This treatment offers a balance of contributions of individual physical phenomena on the liquid breakup process. For the secondary breakup, an addition turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. The drop size

  6. Bubble Rise and Break-Up in Volcanic Conduits

    NASA Astrophysics Data System (ADS)

    Soldati, A.; Cashman, K. V.; Rust, A.; Rosi, M.

    2013-12-01

    The continual passive degassing occurring at open-vent mafic volcanoes is often punctuated by bursts of active degassing. The latter are generally thought to be the result of slug flow: large, conduit-filling bubbles periodically rising up the feeder conduit and bursting at the magma-air interface. Existing models of volcanic degassing systems make the simplifying assumption that the conduit is cylindrical; however, while this may be true at shallow levels, a flaring probably connects it to a dyke-like geometry at depth. The overall goal of this research is to assess the influence of conduit geometry on the speed and stability of bubbles rising in open-vent systems, and ultimately to devise a model to infer conduit shape from emerging bubbles size. In order to do that an analogue experimental approach was used. All of the experiments were two-phase (melt+volatiles); the analogue materials of choice were golden syrup-water mixtures ranging in viscosity from 10-1 to 104 Pa*s and air. Two experimental apparatuses were used: a bi-dimensional and a tri-dimensional one. The bi-dimensional set-up is a cell made of two flat transparent PVC plates (44x23cm) 10mm or 5mm apart (the front one having a hole at the bottom permitting bubble injection) containing a variety of parallelepipeds apt to outline different plumbing system geometries. The tri-dimensional one consists of a cylindrical tube (r=1,5cm; l=7cm) allowing bubble injection through the bottom rubber tap and terminating into a square tank (l=22cm). Results indicate that conduit geometry directly controls the slug rise velocity and the surrounding liquid descending speed, which in turn control the slug stability. Small enough bubbles simply deform as they go through the flaring, while bigger ones split into two daughter bubbles. A regime diagram has been constructed, illustrating the bubble break-up threshold dependence on the flare geometry and initial slug size, the two main controlling factors. The phenomenon of

  7. Tear breakup dynamics: a technique for quantifying tear film instability.

    PubMed

    Begley, Carolyn G; Himebaugh, Nikole; Renner, Debra; Liu, Haixia; Chalmers, Robin; Simpson, Trefford; Varikooty, Jalaiah

    2006-01-01

    The purpose of this study was to develop a novel, quantitative measurement of tear film breakup dynamics (TBUD) to study the phenomenon of tear breakup in dry eye and control subjects and its impact on dry eye symptoms. Ten control and 10 dry eye subjects completed the Dry Eye (DEQ) and other questionnaires. After the instillation of sodium fluorescein, subjects kept the tested eye open for as long as possible, similar to a staring contest, while tear film breakup was videotaped (S-TBUD). The maximum blink interval (MBI) and tear breakup time (TBUT) were measured from digital movies by a masked observer. Individual frames of movies were converted to gray-scale images, maps of relative tear film fluorescence were generated, and the total area of tear breakup (AB) of the exposed cornea was quantified. On average, dry eye subjects demonstrated a higher AB and shorter TBUT and MBI, but only the AB was significantly different (p = 0.023). Subjects most often used the descriptors stinging and burning to describe their sensations during staring trials. The AB showed a high correlation between eyes and with some DEQ symptom measures. These methods allow objective quantification and tracking of the phenomenon of tear breakup. Our results suggest that tear breakup stresses the corneal surface, resulting in stimulation of underlying nociceptors. The tear film of dry eye subjects was less stable than controls. They had a larger AB measured from the last video frame before MBI (i.e., just before blinking) than did controls. This perhaps reflects adaptation to the repeated stress of tear instability in dry eye.

  8. Breakup of Droplets in an Accelerating Gas Flow

    NASA Technical Reports Server (NTRS)

    Dickerson, R. A.; Coultas, T. A.

    1966-01-01

    A study of droplet breakup phenomena by an accelerating gas flow is described. The phenomena are similar to what propellant droplets experience when exposed to accelerating combustion gas flow in a rocket engine combustion zone. Groups of several dozen droplets in the 100-10 750-micron-diameter range were injected into a flowing inert gas in a transparent rectangular nozzle. Motion photography of the behavior of the droplets at various locations in the accelerating gas flow has supplied quantitative and qualitative data on the breakup phenomena which occur under conditions similar to those found in large rocket engine combustors. A blowgun injection device, used to inject very small amounts of liquid at velocities of several hundred feet per second into a moving gas stream, is described. The injection device was used to inject small amounts of liquid RP-1 and water into the gas stream at a velocity essentially equal to the gas velocity where the group of droplets was allowed to stabilize its formation in a constant area section before entering the convergent section of the transparent nozzle. Favorable comparison with the work of previous investigators who have used nonaccelerating gas flow is found with the data obtained from this study with accelerating gas flow. The criterion for the conditions of minimum severity required to produce shear-type droplet breakup in an accelerating gas flow is found to agree well with the criterion previously established at Rocketdyne for breakup in nonaccelerating flow. An extension of the theory of capillary surface wave effects during droplet breakup is also presented. Capillary surface waves propagating in the surface of the droplet, according to classical hydrodynamical laws, are considered. The waves propagate tangentially over the surface of the droplet from the forward stagnation point to the major diameter. Consideration of the effects of relative gas velocity on the amplitude growth of these waves allows conclusions to be

  9. Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup

    PubMed Central

    Keshavarz, Bavand

    2016-01-01

    Understanding the elongational rheology of dilute polymer solutions plays an important role in many biological and industrial applications ranging from microfluidic lab-on-a-chip diagnostics to phenomena such as fuel atomization and combustion. Making quantitative measurements of the extensional viscosity for dilute viscoelastic fluids is a long-standing challenge and it motivates developments in microfluidic fabrication techniques and high speed/strobe imaging of millifluidic capillary phenomena in order to develop new classes of instruments. In this paper, we study the elongational rheology of a family of dilute polymeric solutions in two devices: first, steady pressure-driven flow through a hyperbolic microfluidic contraction/expansion and, second, the capillary driven breakup of a thin filament formed from a small diameter jet (Dj∼O(100 μm)). The small length scale of the device allows very large deformation rates to be achieved. Our results show that in certain limits of low viscosity and elasticity, jet breakup studies offer significant advantages over the hyperbolic channel measurements despite the more complex implementation. Using our results, together with scaling estimates of the competing viscous, elastic, inertial and capillary timescales that control the dynamics, we construct a dimensionless map or nomogram summarizing the operating space for each instrument. PMID:27375824

  10. The breakup mechanism of biomolecular and colloidal aggregates in a shear flow

    NASA Astrophysics Data System (ADS)

    Ó Conchúir, Breanndán; Zaccone, Alessio

    2014-03-01

    The theory of self-assembly of colloidal particles in shear flow is incomplete. Previous analytical approaches have failed to capture the microscopic interplay between diffusion, shear and intermolecular interactions which controls the aggregates fate in shear. In this work we analytically solved the drift-diffusion equation for the breakup rate of a dimer in flow. Then applying rigidity percolation theory, we found that the lifetime of a generic cluster formed under shear is controlled by the typical lifetime of a single bond in its interior, which in turn depends on the efficiency of the stress transmitted from other bonds in the cluster. We showed that aggregate breakup is a thermally-activated process where the activation energy is controlled by the interplay between intermolecular forces and the shear drift, and where structural parameters determine whether cluster fragmentation or surface erosion prevails. In our latest work, we analyzed floppy modes and nonaffine deformations to derive a lower bound on the fractal dimension df below which aggregates are mechanically unstable, ie. for large aggregates df ~= 2.4. This theoretical framework is in quantitative agreement with experiments and can be used for population balance modeling of colloidal and protein aggregation.

  11. Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup.

    PubMed

    Keshavarz, Bavand; McKinley, Gareth H

    2016-07-01

    Understanding the elongational rheology of dilute polymer solutions plays an important role in many biological and industrial applications ranging from microfluidic lab-on-a-chip diagnostics to phenomena such as fuel atomization and combustion. Making quantitative measurements of the extensional viscosity for dilute viscoelastic fluids is a long-standing challenge and it motivates developments in microfluidic fabrication techniques and high speed/strobe imaging of millifluidic capillary phenomena in order to develop new classes of instruments. In this paper, we study the elongational rheology of a family of dilute polymeric solutions in two devices: first, steady pressure-driven flow through a hyperbolic microfluidic contraction/expansion and, second, the capillary driven breakup of a thin filament formed from a small diameter jet ([Formula: see text]). The small length scale of the device allows very large deformation rates to be achieved. Our results show that in certain limits of low viscosity and elasticity, jet breakup studies offer significant advantages over the hyperbolic channel measurements despite the more complex implementation. Using our results, together with scaling estimates of the competing viscous, elastic, inertial and capillary timescales that control the dynamics, we construct a dimensionless map or nomogram summarizing the operating space for each instrument.

  12. Morphological classification of low viscosity drop bag breakup in a continuous air jet stream

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Liu, Hai-Feng; Li, Wei-Feng; Xu, Jian-Liang

    2010-11-01

    To investigate the effect of Rayleigh-Taylor wave number in the region of maximum cross stream dimension (NRT) on drop breakup morphology, the breakup properties of accelerating low viscosity liquid drops (water and ethanol drops, diameter=1.2-6.6 mm, Weber number=10-80) were investigated using high-speed digital photography. The results of morphological analysis show a good correlation of the observed breakup type with NRT; bag breakup occurred when NRT was 1/√3 -1, bag-stamen breakup at 1-2, and dual-bag breakup at 2-3. The number of nodes in bag breakup, bag-stamen breakup, and dual-bag breakup all increased with Weber number. The experimental results are consistent with the model estimates and in good agreement with those reported in the literature.

  13. Inclusive breakup of three-fragment weakly bound nuclei

    NASA Astrophysics Data System (ADS)

    Carlson, B. V.; Frederico, T.; Hussein, M. S.

    2017-04-01

    The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.

  14. Dynamics of bubble breakup at a T junction.

    PubMed

    Lu, Yutao; Fu, Taotao; Zhu, Chunying; Ma, Youguang; Li, Huai Z

    2016-02-01

    The gas-liquid interfacial dynamics of bubble breakup in a T junction was investigated. Four regimes were observed for a bubble passing through the T junction. It was identified by the stop flow that a critical width of the bubble neck existed: if the minimum width of the bubble neck was less than the critical value, the breakup was irreversible and fast; while if the minimum width of the bubble neck was larger than the critical value, the breakup was reversible and slow. The fast breakup was driven by the surface tension and liquid inertia and is independent of the operating conditions. The minimum width of the bubble neck could be scaled with the remaining time as a power law with an exponent of 0.22 in the beginning and of 0.5 approaching the final fast pinch-off. The slow breakup was driven by the continuous phase and the gas-liquid interface was in the equilibrium stage. Before the appearance of the tunnel, the width of the depression region could be scaled with the time as a power law with an exponent of 0.75; while after that, the width of the depression was a logarithmic function with the time.

  15. Breakup of {sup 11}B at low relative energies

    SciTech Connect

    Bryan, D.C.; White, C.A.; Wolfs, F.L.H.

    1993-04-01

    The authors have used the segmented focal plane detector of the Rochester Enge split-pole spectrograph to study the breakup of 87 MeV {sup 11}B ions incident on a {sup 12}C target into {sup 4}He and {sup 7}Li fragments at relative energies between 0 MeV and 4 MeV and at laboratory angles between 7.5{degrees} and 25{degrees}. The total kinetic energy spectra of the breakup fragments is dominated by elastic breakup (all reaction products are left in their ground state). The reconstructed relative energy spectra for elastic breakup are dominated by sequential breakup of {sup 11}B via the 9.27 MeV, 10.26 MeV, and 10.60 MeV excited states in {sup 11}B. The measured yields are compared with the calculated cross sections of exciting these states, using DWBA calculations and B(EL) values obtained from radiative capture measurements of {sup 4}He and {sup 7}Li.

  16. History of satellite break-ups in space

    NASA Technical Reports Server (NTRS)

    Gabbard, J.

    1985-01-01

    By 28 June 1961 the 1st Aerospace Control Squadron had cataloged 115 Earth orbiting satellites from data supplied by a rather diverse collection of radar and optical sensors. On 29 June 1961, the Able Star rocket of the 1961 Omicron launch exploded causing a quantum jump in the number of Earth orbiting objects. Since that time there have been 69 Earth orbiting satellites break up in space whose debris remained in orbit long enough for orbital elements to be developed. A list of the 69 breakups is provided. The debris from some of the lower altitude breakups has all decayed. Among the 69 breakups, 44 have cataloged debris remaining in orbit. As of 1 July 1982, the size of the cataloged orbiting population was exactly 4700. Forty-nine percent of these objects are fragments of the forty-four breakups. For each breakup the various orbits of its debris represent a family of orbits that are related in characteristics due to their common impulse launch. A few examples are shown of how the families are oriented in space.

  17. History of satellite break-ups in space

    NASA Technical Reports Server (NTRS)

    Gabbard, J.

    1985-01-01

    By 28 June 1961 the 1st Aerospace Control Squadron had cataloged 115 Earth orbiting satellites from data supplied by a rather diverse collection of radar and optical sensors. On 29 June 1961, the Able Star rocket of the 1961 Omicron launch exploded causing a quantum jump in the number of Earth orbiting objects. Since that time there have been 69 Earth orbiting satellites break up in space whose debris remained in orbit long enough for orbital elements to be developed. A list of the 69 breakups is provided. The debris from some of the lower altitude breakups has all decayed. Among the 69 breakups, 44 have cataloged debris remaining in orbit. As of 1 July 1982, the size of the cataloged orbiting population was exactly 4700. Forty-nine percent of these objects are fragments of the forty-four breakups. For each breakup the various orbits of its debris represent a family of orbits that are related in characteristics due to their common impulse launch. A few examples are shown of how the families are oriented in space.

  18. Current reduction in a pseudo-breakup event: THEMIS observations

    NASA Astrophysics Data System (ADS)

    Yao, Z. H.; Pu, Z. Y.; Owen, C. J.; Fu, S. Y.; Chu, X. N.; Liu, J.; Angelopoulos, V.; Rae, I. J.; Yue, C.; Zhou, X.-Z.; Zong, Q.-G.; Cao, X.; Shi, Q. Q.; Forsyth, C.; Du, A. M.

    2014-10-01

    Pseudo-breakup events are thought to be generated by the same physical processes as substorms. This paper reports on the cross-tail current reduction in an isolated pseudo-breakup observed by three of the THEMIS probes (THEMIS A (THA), THEMIS D (THD), and THEMIS E (THE)) on 22 March 2010. During this pseudo-breakup, several localized auroral intensifications were seen by ground-based observatories. Using the unique spatial configuration of the three THEMIS probes, we have estimated the inertial and diamagnetic currents in the near-Earth plasma sheet associated with flow braking and diversion. We found the diamagnetic current to be the major contributor to the current reduction in this pseudo-breakup event. During flow braking, the plasma pressure was reinforced, and a weak electrojet and an auroral intensification appeared. After flow braking/diversion, the electrojet was enhanced, and a new auroral intensification was seen. The peak current intensity of the electrojet estimated from ground-based magnetometers, ~0.7 × 105 A, was about 1 order of magnitude lower than that in a typical substorm. We suggest that this pseudo-breakup event involved two dynamical processes: a current-reduction associated with plasma compression ahead of the earthward flow and a current-disruption related to the flow braking/diversion. Both processes are closely connected to the fundamental interaction between fast flows, the near-Earth ambient plasma, and the magnetic field.

  19. A new model to simulate impact breakup

    NASA Astrophysics Data System (ADS)

    Cordelli, Alessandro; Farinella, Paolo

    1997-12-01

    energies) the occurrence of catastrophic breakup. The masses and velocities of the fragments resemble those found in laboratory impact experiments.

  20. Capillary break-up, gelation and extensional rheology of hydrophobically modified cellulose ethers

    NASA Astrophysics Data System (ADS)

    Sharma, Vivek; Haward, Simon; Pessinet, Olivia; Soderlund, Asa; Threlfall-Holmes, Phil; McKinley, Gareth

    2012-02-01

    Cellulose derivatives containing associating hydrophobic groups along their hydrophilic polysaccharide backbone are used extensively in the formulations for inks, water-borne paints, food, nasal sprays, cosmetics, insecticides, fertilizers and bio-assays to control the rheology and processing behavior of multi-component dispersions. These complex dispersions are processed and used over a broad range of shear and extensional rates. The presence of hydrophobic stickers influences the linear and nonlinear rheology of cellulose ether solutions. In this talk, we systematically contrast the difference in the shear and extensional rheology of a cellulose ether: ethy-hydroxyethyl-cellulose (EHEC) and its hydrophobically-modified analog (HMEHEC) using microfluidic shear rheometry at deformation rates up to 10^6 inverse seconds, cross-slot flow extensional rheometry and capillary break-up during jetting as a rheometric technique. Additionally, we provide a constitutive model based on fractional calculus to describe the physical gelation in HMEHEC solutions.

  1. Influence of offset weak zones on the development of rift basins: Activation and abandonment during continental extension and breakup

    NASA Astrophysics Data System (ADS)

    Chenin, Pauline; Beaumont, Christopher

    2013-04-01

    We use numerical modelling to investigate reactivation of inherited Offset Weak Zones (OWZ) in continental crust and Mantle Weak Zones (MWZ) to form offset rift basins during continental rifting and breakup. Offset rift basins are basins that are set off/offset from the main rift/locus of breakup. Weak zones embedded in a stiff layer are preferentially and rapidly reactivated, whereas the same zones are either ignored or slowly reactivated when embedded in pliable layers. Here stiff implies a nonlinear flow law with a high stress exponent (n > ˜ 10,000), a plastic material, and pliable means a low stress exponent (n ˜ 2-5) as in ductile, power-law creep of rocks. Whether offset rift basins form during rifting of a composite lithosphere (i.e., comprising stiff and pliable layers) depends on the competition between necking instabilities that develop at the weak zones in the stiff layers, and the coupling between the stiff and pliable layers. Stiff/cratonic lithosphere results in early localization of the deformation at the MWZ, rapid necking and breakup without developing offset rift basins. In contrast, warm pliable lithosphere develops significant offset basins and has protracted rifting because the MWZ is now embedded in a pliable layer. We also investigate the influence of OWZ dip, sedimentation, and the sensitivity of reactivation to the distance from OWZ to the MWZ, and to the size of the MWZ. A tectonic rifting styles diagram is used to show that the model results agree with natural examples.

  2. Madelung Deformity.

    PubMed

    Kozin, Scott H; Zlotolow, Dan A

    2015-10-01

    Madelung deformity of the wrist is more common in females and is often associated with Leri Weill dyschondrosteosis, a mesomelic form of dwarfism. Patients with Madelung deformity often report wrist deformity resulting from the prominence of the relatively long ulna. The typical Madelung deformity is associated with a Vickers ligament that creates a tether across the volar-ulnar radial physis that restricts growth across this segment. The distal radius deforms in the coronal (increasing radial inclination) and the sagittal (increasing volar tilt) planes. There is lunate subsidence and the proximal carpal row adapts to the deformity by forming an upside-down pyramid shape or triangle. Treatment depends on the age at presentation, degree of deformity, and magnitude of symptoms. Mild asymptomatic deformity warrants a period of nonsurgical management with serial x-ray examinations because the natural history is unpredictable. Many patients never require surgical intervention. Progressive deformity in the young child with considerable growth potential remaining requires release of Vickers ligament and radial physiolysis to prevent ongoing deterioration Concomitant ulnar epiphysiodesis may be necessary. Advanced asymptomatic deformity in older children with an unacceptable-appearing wrist or symptomatic deformity are indications for surgery. A dome osteotomy of the radius allows 3-dimensional correction of the deformity. Positive radiographic and clinical results after dome osteotomy have been reported. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  3. Review of semi-classical calculations for breakup

    SciTech Connect

    Baye, Daniel

    2005-10-14

    In semi-classical approximations, the relative motion between target and projectile is represented by a classical trajectory but the projectile internal motion is treated quantum mechanically. A time-dependent Schroedinger equation describes the breakup of exotic nuclei induced by the Coulomb and nuclear forces. Different accurate techniques of resolution of this time-dependent equation are reviewed for one space dimension. The respective merits of their extensions to three dimensions are compared. Applications to the breakup of the 11Be, 15C, and 19C halo nuclei are presented and discussed. The first-order perturbation theory is compared with the time-dependent method and its relevance for the Coulomb breakup determination of the astrophysical S factor is analyzed.

  4. Modeling Tear Film Evaporation and Breakup with Duplex Films

    NASA Astrophysics Data System (ADS)

    Stapf, Michael; Braun, Richard; Begley, Carolyn; Driscoll, Tobin; King-Smith, Peter Ewen

    2015-11-01

    Tear film thinning, hyperosmolarity, and breakup can irritate and damage the ocular surface. Recent research hypothesizes deficiencies in the lipid layer may cause locally increased evaporation, inducing conditions for breakup. We consider a model for team film evolution incorporating two mobile fluid layers, the aqueous and lipid layers. In addition, we include the effects of salt concentration, osmosis, evaporation as modified by the lipid layer, and the polar portion of the lipid layer. Numerically solving the resulting model, we explore the conditions for tear film breakup and analyze the response of the system to changes in our parameters. Our studies indicate sufficiently fast peak values or sufficiently wide areas of evaporation promote TBU, as does diffusion of solutes. In addition, the Marangoni effect representing polar lipids dominates viscous dissipation from the non-polar lipid layer in the model. This work was supported in part by NSF grant 1412085 and NIH grant 1R01EY021794.

  5. Effect of boiling regime on melt stream breakup in water

    SciTech Connect

    Spencer, B.W.; Gabor, J.D.; Cassulo, J.C.

    1986-01-01

    A study has been performed examining the breakup and mixing behavior of an initially coherent stream of high-density melt as it flows downward through water. This work has application to the quenching of molten core materials as they drain downward during a postulated severe reactor accident. The study has included examination of various models of breakup distances based upon interfacial instabilities dominated either by liquid-liquid contact or by liquid-vapor contact. A series of experiments was performed to provide a data base for assessment of the various modeling approaches. The experiments involved Wood's metal (T/sub m/ = 73/sup 0/C, rho = 9.2 g/cm/sup 3/, d/sub j/ = 20 mm) poured into a deep pool of water. The temperature of the water and wood's metal were varied to span the range from single-phase, liquid-liquid contact to the film boiling regime. Experiment results showed that breakup occurred largely as a result of the spreading and entrainment from the leading edge of the jet. However, for streams of sufficient lengths a breakup length could be discerned at which there was no longer a coherent central core of the jet to feed the leading edge region. The erosion of the vertical trailing column is by Kelvin-Helmoltz instabilities and related disengagement of droplets from the jet into the surrounding fluid. For conditions of liquid-liquid contact, the breakup length has been found to be about 20 jet diameters; when substantial vapor is produced at the interface due to heat transfer from the jet to the water, the breakup distance was found to range to as high as 50 jet diameters. The former values are close to the analytical prediction of Taylor, whereas the latter values are better predicted by the model of Epstein and Fauske.

  6. Forecast Tools for Alaska River Ice Breakup Timing and Severity

    NASA Astrophysics Data System (ADS)

    Moran, E. H.; Lindsey, S.; van Breukelen, C. M.; Thoman, R.

    2016-12-01

    Spring Breakup on the large interior rivers in Alaska means a time of nervous anticipation for many of the residents in the villages alongside those rivers. On the Yukon and Kuskokwim Rivers the record flood for most villages occurred as a result of ice jams that backed up water and dump truck sized ice floes into the village. Those floods can occur suddenly and can literally wipe out a village. The challenge is that with a limited observation network (3 automated USGS gages along the 1200 miles of the Yukon River flowing through Alaska) and the inherently transient nature of ice jam formation, prediction of the timing and severity of these events has been a tremendous challenge. Staff at the Alaska Pacific River Forecast Center as well as the Alaska Region Climate Program Manager have been developing more quantitative tools to attempt to provide a longer lead time for villages to prepare for potentially devastating flooding. In the past, a very qualitative assessment of the primary drivers of Spring Breakup (snow pack, river ice thickness and forecast spring weather) have led to the successful identification of years when flood severity was likely to be elevated or significantly decreased. These qualitative assessments have also allowed the forecasting of the probability of either a thermal or a dynamic breakup. But there has continued to be a need for an objective tool that can handle weather patterns that border on the tails of the climatic distributions as well as the timing and flood potential from weather patterns that are closer to the median of the distribution. Over the past 8 years there have been a significant number of years with anomalous spring weather patterns including cold springs followed by rapid warmups leading to record flooding from ice jams during spring breakup (2009, 2013), record late breakup (2013), record early breakup (2016), record high snowfall (2012), record snowmelt and aufeis flooding (2015) and record low snowfall (2015). The need

  7. Asymptotic and near-target direct breakup of 6Li and 7Li

    NASA Astrophysics Data System (ADS)

    Kalkal, Sunil; Simpson, E. C.; Luong, D. H.; Cook, K. J.; Dasgupta, M.; Hinde, D. J.; Carter, I. P.; Jeung, D. Y.; Mohanto, G.; Palshetkar, C. S.; Prasad, E.; Rafferty, D. C.; Simenel, C.; Vo-Phuoc, K.; Williams, E.; Gasques, L. R.; Gomes, P. R. S.; Linares, R.

    2016-04-01

    Background: Li,76 and 9Be are weakly bound against breakup into their cluster constituents. Breakup location is important for determining the role of breakup in above-barrier complete fusion suppression. Recent works have pointed out that experimental observables can be used to separate near-target and asymptotic breakup. Purpose: Our purpose is to distinguish near-target and asymptotic direct breakup of Li,76 in reactions with nuclei in different mass regions. Method: Charged particle coincidence measurements are carried out with pulsed Li,76 beams on 58Ni and 64Zn targets at sub-barrier energies and compared with previous measurements using 208Pb and 209Bi targets. A detector array providing a large angular coverage is used, along with time-of-flight information to give definitive particle identification of the direct breakup fragments. Results: In interactions of 6Li with 58Ni and 64Zn, direct breakup occurs only asymptotically far away from the target. However, in interactions with 208Pb and 209Bi, near-target breakup occurs in addition to asymptotic breakup. Direct breakup of 7Li into α -t is not observed in interactions with 58Ni and 64Zn. However, near-target dominated direct breakup was observed in measurements with 208Pb and 209Bi. A modified version of the Monte Carlo classical trajectory model code platypus, which explicitly takes into account lifetimes associated with unbound states, is used to simulate sub-barrier breakup reactions. Conclusions: Near-target breakup in interactions with Li,76 is an important mechanism only for the heavy targets 208Pb and 209Bi. There is insignificant near-target direct breakup of 6Li and no direct breakup of 7Li in reactions with 58Ni and 64Zn. Therefore, direct breakup is unlikely to suppress the above-barrier fusion cross section in reactions of Li,76 with 58Ni and 64Zn nuclei.

  8. Color Breakup In Sequentially-Scanned LC Displays

    NASA Technical Reports Server (NTRS)

    Arend, L.; Lubin, J.; Gille, J.; Larimer, J.; Statler, Irving C. (Technical Monitor)

    1994-01-01

    In sequentially-scanned liquid-crystal displays the chromatic components of color pixels are distributed in time. For such displays eye, head, display, and image-object movements can cause the individual color elements to be visible. We analyze conditions (scan designs, types of eye movement) likely to produce color breakup.

  9. Breakup of New Orleans Households after Hurricane Katrina

    ERIC Educational Resources Information Center

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household breakup resulting from Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads…

  10. Cumulative beam breakup with time-dependent parameters

    SciTech Connect

    Jean Delayen

    2004-08-01

    A general analytical formalism developed recently for cumulative beam breakup (BBU) in linear accelerators with arbitrary beam current profile and misalignments [1, 2] is extended to include time-dependent parameters such as energy chirp or rf focusing in order to reduce BBU-induced instabilities and emittance growth. Analytical results are presented and applied to practical accelerator configurations.

  11. Framework for Control of Dynamic Ice Breakup by River Regulation

    DTIC Science & Technology

    1989-06-01

    and if ration. Other important characteristics of these wave formation occurs upstream or in a tribu - waves are significant stage increase, short dura...stage must occur to produce the high forces cut River danis for a controlled ice lireakup experi- needed for a dynamic breakup, and very high 1e1it

  12. Breakup of New Orleans Households after Hurricane Katrina

    ERIC Educational Resources Information Center

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household breakup resulting from Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads…

  13. Mass estimation in the breakups of Soviet satellites

    NASA Technical Reports Server (NTRS)

    Badhwar, Gautam D.; Anz-Meador, Phillip D.

    1990-01-01

    An attempt is made to estimate the mass of the parent satellite from the mass of the debris remaining from its breakup using a technique based on the decay rate and radar cross-section time history. The decay of perigee and apogee with time of an object in orbit provides the area-to-mass ratio and the radar cross-section provides a measure of the effective area of the object, while combining the two gives the mass of the object. The technique has been successfully applied to 12 U.S. breakups and one Arianespace breakup. Calculations exhibiting good agreement with reference mass are also discussed for Soviet intact C-class boosters, intact ASAT target satellites, and intact navigational satellites. It is found that the calculated mass of the ASAT interceptor spacecraft is about one-half of the expected mass, but it is pointed out that this may be due to fuel carried on board. For ASAT target breakups the calculated mass is 20-30 times too low; no clear explanation can yet be found for this phenomenon.

  14. A fundamental study of liquid phase particle breakup. Revision

    NASA Astrophysics Data System (ADS)

    1984-12-01

    Combustion efficiency of aluminized propellants in solid rocket motors is reduced by incomplete aluminum combustion and two-phase nozzle flow losses. Combustion of these propellants can produce large Al/Al2O3 agglomerates. As a direct result of agglomerate breakup, the aluminum combustion rate is increased, and the thermal energy released is more efficiently transferred into exhaust kinetic energy. This research sought to obtain physical data to characterize the mechanisms of aerodynamic droplet breakup. Experiments have been completed in which conventional liquids and a liquid metal (mercury) was studied. The primary goal of the conventional liquid experiments was to examine the effect of liquid properties (viscosity and surface tension) on the breakup mechanism, time scale, and fragment size distribution. The goal of the mercury experiments was to examine the effect of the much higher surface tension more characteristic of liquid aluminum. A key element of the experimental effort is the use of nonintrusive laser diagnostics including pulsed laser holography (PLH) and laser Doppler velocimetry (LDV). The exceptional temporal and spatial resolution of PLH provided the ability to resolve the mechanism of breakup and the size distribution of the fragments. LDV was used to determine drop velocity distributions along the nozzle revealing the rapid acceleration of the flattened droplets and then, surprisingly, the milder acceleration of the fragments.

  15. Armor breakup and reformation in a degradational laboratory experiment

    NASA Astrophysics Data System (ADS)

    Orrú, Clara; Blom, Astrid; Uijttewaal, Wim S. J.

    2016-06-01

    Armor breakup and reformation was studied in a laboratory experiment using a trimodal mixture composed of a 1 mm sand fraction and two gravel fractions (6 and 10 mm). The initial bed was characterized by a stepwise downstream fining pattern (trimodal reach) and a downstream sand reach, and the experiment was conducted under conditions without sediment supply. In the initial stage of the experiment an armor formed over the trimodal reach. The formation of the armor under partial transport conditions led to an abrupt spatial transition in the bed slope and in the mean grain size of the bed surface, as such showing similar results to a previous laboratory experiment conducted with a bimodal mixture. The focus of the current analysis is to study the mechanisms of armor breakup. After an increase in flow rate the armor broke up and a new coarser armor quickly formed. The breakup initially induced a bed surface fining due to the exposure of the finer substrate, which was accompanied by a sudden increase in the sediment transport rate, followed by the formation of an armor that was coarser than the initial one. The reformation of the armor was enabled by the supply of coarse material from the upstream degrading reach and the presence of gravel in the original substrate sediment. Here armor breakup and reformation enabled slope adjustment such that the new steady state was closer to normal flow conditions.

  16. Properties of spray formation by turbulent primary breakup

    NASA Astrophysics Data System (ADS)

    Sallam, Khaled Abd-Elmonem

    The formation of drops at the surface of turbulent liquids, e.g., turbulent primary breakup, was studied due to the importance of this mechanism for a variety of natural and technological spray formation processes, e.g., white caps on water, water falls, white water rapids, bow waves of ships, and many types of commercial spray atomizers, among others. Pulsed shadowgraphy and holography were used to observe the properties of the liquid surface and the drops formed by turbulent primary breakup of liquid jets in still air. Measured properties included liquid surface velocities, conditions at the onset of ligament and drop formation, ligament and drop sizes, ligament and drop velocities, rates of drop formation and the lengths of the liquid jets. Phenomenological theories were used to help interpret and correlate the measurements. Present results show that the onset of ligament formation occurs once the kinetic energy of the turbulent eddies that form the ligaments exceeds the required surface tension energy of a ligament of comparable size. Subsequently, the onset of drop formation occurs once drops form at the tips of ligaments due to classical Rayleigh breakup. This same mechanism controls the subsequent variation of drop sizes due to turbulent primary breakup as a function of distance from the jet exit. Breakup of the entire liquid jet occurs in two ways: a turbulent mechanism where the drops formed by turbulent primary breakup became comparable to the size of the liquid jet itself, and an aerodynamic mechanism where large turbulent eddies place the liquid jet in cross flow. In addition, ligament and drop velocities were associated with mean and fluctuating velocities of the liquid, and rates of drop formation could be expressed by surface efficiency factors defined as the fraction of the maximum cross stream liquid mass flux. Liquid volume fraction measurements indicated a rather dilute spray structure in contrast to earlier speculations. Finally, the turbulence

  17. The role of deep subduction in supercontinent breakup

    NASA Astrophysics Data System (ADS)

    Capitanio, Fabio; Dal Zilio, Luca; Faccenda, Manuele

    2016-04-01

    The breakup of continents is a crucial stage of the episodic aggregation and dispersal of tectonic plates. In particular, the transition from a stable supercontinent to its rifting, breakup and subsequent drifting is one of the least understood aspects of plate tectonics. Over the last decades, several works have highlighted the potential role of pre-existing weaknesses or that of raising mantle plumes in assisting the localization of strain. However, to sustain large-scale divergent regime over geological time, extensional stresses are strictly required. Here we present results from 2-D thermo-mechanical numerical experiments and we show that rifting and drifting of continents result from lithospheric subduction at convergent margins, when this extends to lower mantle depths. We quantify the drag exerted by subduction-induced mantle flow along the basal surface of continental plates, comparing models where lithospheric slabs stagnate above the upper-lower mantle boundary with those where slabs penetrate into the lower mantle. When subduction is upper mantle-confined, divergent basal tractions localize at distances comparable to the effective upper mantle thickness (~500 km), causing the breakup of a microcontinent and opening of a marginal basin. Instead, when the descending lithosphere subducts deeper, extensional stresses localize at greater distances from the trench (≥ 2900 km), are higher and are sustained over a longer time. Although relatively low, basal shear stresses integrated over large plates generate tension forces that may exceed the strength of the continental lithosphere, eventually leading to breakup and opening of an intervening distal basin. The models illustrate that the mechanism leading to the formation of back-arc basins above upper mantle-confined subduction provides a viable explanation for the opening of larger basins above deeper subduction. Examples include the Atlantic Ocean formation and the South and North American plates drifting

  18. Automatic Word Alignment

    DTIC Science & Technology

    2014-02-18

    for each of the paired units includes forming a first alignment of units of the first language to units of the second language, and forming a second...alignment of units of the second language to units of the first language . The alignment parameters include a first set of parameters for forming an...alignment from the first language to the second language and a second set of parameters for forming an align­ ment from the second language to the

  19. Shear alignment of a disordered lamellar mesophase.

    PubMed

    Kumaran, V; Raman, D S S

    2011-03-01

    The shear alignment of an initially disordered lamellar phase is examined using lattice Boltzmann simulations of a mesoscopic model based on a free-energy functional for the concentration modulation. For a small shear cell of width 8λ, the qualitative features of the alignment process are strongly dependent on the Schmidt number Sc=ν/D (ratio of kinematic viscosity and mass diffusion coefficient). Here, λ is the wavelength of the concentration modulation. At low Schmidt number, it is found that there is a significant initial increase in the viscosity, coinciding with the alignment of layers along the extensional axis, followed by a decrease at long times due to the alignment along the flow direction. At high Schmidt number, alignment takes place due to the breakage and reformation of layers because diffusion is slow compared to shear deformation; this results in faster alignment. The system size has a strong effect on the alignment process; perfect alignment takes place for a small systems of width 8λ and 16λ, while a larger system of width 32λ does not align completely even at long times. In the larger system, there appears to be a dynamical steady state in which the layers are not perfectly aligned--where there is a balance between the annealing of defects due to shear and the creation due to an instability of the aligned lamellar phase under shear. We observe two types of defect creation mechanisms: the buckling instability under dilation, which was reported earlier, as well as a second mechanism due to layer compression.

  20. Breakup characteristics of a liquid jet in subsonic crossflow

    NASA Astrophysics Data System (ADS)

    Gopala, Yogish

    This thesis describes an experimental investigation of the breakup processes involved in the formation of a spray created by a liquid jet injected into a gaseous crossflow. This work is motivated by the utilization of this method to inject fuel in combustors and afterburners of airplane engines. This study aims to develop a better understanding of the spray breakup processes and to provide better experimental inputs to improve the fidelity of numerical models. A review of the literature in this field identified the fundamental physical processes involved in the breakup of the spray and the dependence of spray properties on operating conditions. The time taken for the liquid column to break up into ligaments and droplets, the primary breakup time and the effect of injector geometry on the spray formation processes and spray properties as the key research areas in which research done so far has been inadequate. Determination of the location where the liquid column broke up was made difficult by the presence of a large number of droplets surrounding it. This study utilizes the liquid jet light guiding technique that enables accurate measurements of this location for a wide range of operating conditions. Prior to this study, the primary breakup time was thought to be a function the density ratio of the liquid and the gas, the diameter of the orifice and the air velocity. This study found that the time to breakup of the liquid column depends on the Reynolds number of the liquid jet. This suggests that the breakup of a turbulent liquid jet is influenced by both the aerodynamic breakup processes and the turbulent breakup processes. Observations of the phenomenon of the liquid jet splitting up into two or more jets were made at some operating conditions with the aid of the new visualization technique. Finally, this thesis investigates the effect of injector geometry on spray characteristics. One injector was a round edged orifice with a length to diameter ratio of 1 and a

  1. Orogenic inheritance and continental breakup: Wilson Cycle-control on rift and passive margin evolution

    NASA Astrophysics Data System (ADS)

    Schiffer, C.; Petersen, K. D.

    2016-12-01

    Rifts often develop along suture zones between previously collided continents, as part of the Wilson cycle. The North Atlantic is such an example, formed where Pangaea broke apart along Caledonian and Variscan sutures. Dipping upper mantle structures in E. Greenland and Scotland, have been interpreted as fossil subduction zones and the seismic signature indicates the presence of eclogite and serpentinite. We speculate that this orogenic material may impose a rheological control upon post-orogenic extension and we use thermo-mechanical modelling to explore such effects. Our model includes the following features: 1) Crustal thickness anomalies, 2) Eclogitised mafic crust emplaced in the mantle lithosphere, and 3) Hydrated mantle peridotite (serpentinite) formed in a pre-rift subduction setting. Our models indicate that the inherited structures control the location and the structural and magmatic evolution of the rift. Rifting of thin initial crust allows for relatively large amounts of serpentinite to be preserved within the uppermost mantle. This facilitates rapid continental breakup and serpentinite exhumation. Magmatism does not occur before continental breakup. Rifts in thicker crust preserve little or no serpentinite and thinning is more focused in the mantle lithosphere, rather than in the crust. Continental breakup is therefore preceded by magmatism. This implies that pre-rift orogenic properties may determine whether magma-poor or magma-rich conjugate margins are formed. Our models show that inherited orogenic eclogite and serpentinite are deformed and partially emplaced either as dipping structures within the lithospheric mantle or at the base of the thinned continental crust. The former is consistent with dipping sub-Moho reflectors often observed in passive margins. The latter provides an alternative interpretation of `lower crustal bodies' which are often regarded as igneous bodies. An additional implication of our models is that serpentinite, often

  2. Post-breakup topographic rejuvenation of passive margins is directly related to the architecture of hyperextension

    NASA Astrophysics Data System (ADS)

    Redfield, Tim; Terje Osmundsen, Per

    2014-05-01

    Post-breakup topographic rejuvenation of individual escarpment sectors atop passive continental margins has been documented for decades. In two recent publications we have identified and quantified a scaling relationship that links the width of a proximal margin sector to the absolute elevation of its seaward-facing escarpment. The scaling relationship appears to be valid, globally, on margin sectors where hyperextended crustal architecture is present offshore (see Osmundsen & Redfield, 2011). In a detailed test we have also documented clear correlations between the geomorphic characteristics of the Scandinavian hinterland backslope, its point of flexure against the Archean craton, today's seismicity, and the now-offshore Taper Break, or the point of deformation coupling/decoupling that was active during high-beta thinning (see Redfield & Osmundsen, 2013). In one particularly fine example the More og Trondelag Fault Complex is shown to have reactivated in accordance with a normal displacement gradient that in turn obeys a simple distance relationship with the Taper Break. These results demonstrate that the topographic fate of a passive margin is determined by the end of the rift phase, and is directly related to the pattern of large-magnitude extensional faults that created the crustal taper and decided the location of the Taper Break. Post-breakup and/or 'accommodation-phase' uplift at passive margins is the inexorable and penultimate phase of hyperextension and is independent of external factors such as mantle convection, lithoshpheric composition/delamination, glacial history, magmatic style, or far field stresses such as those postulated from 'ridge push' or changes in plate motion. Osmundsen & Redfield, 2011, Terra Nova, 23, 349-361. Redfield & Osmundsen, 2013, GSA Bulletin, 125, 184-200.

  3. Breakup dynamics and dripping-to-jetting transition in a Newtonian/shear-thinning multiphase microsystem.

    PubMed

    Ren, Yong; Liu, Zhou; Shum, Ho Cheung

    2015-01-07

    The breakup dynamics in non-Newtonian multiphase microsystems is associated with a variety of industrial applications such as food production and biomedical engineering. In this study, we numerically and experimentally characterize the dripping-to-jetting transition under various flow conditions in a Newtonian/shear-thinning multiphase microsystem. Our work can help to predict the formation of undesirable satellite droplets, which is one of the challenges in dispensing non-Newtonian fluids. We also demonstrate the variations in breakup dynamics between shear-thinning and Newtonian fluids under the same flow conditions. For shear-thinning fluids, the droplet size increases when the capillary number is smaller than a critical value, while it decreases when the capillary number is beyond the critical value. The variations highlight the importance of rheological effects in flows with a non-Newtonian fluid. The viscosity of shear-thinning fluids significantly affects the control over the droplet size, therefore necessitating the manipulation of the shear rate through adjusting the flow rate and the dimensions of the nozzle. Consequently, the droplet size can be tuned in a controlled manner. Our findings can guide the design of novel microdevices for generating droplets of shear-thinning fluids with a predetermined droplet size. This enhances the ability to fabricate functional particles using an emulsion-templated approach. Moreover, elastic effects are also investigated experimentally using a model shear-thinning fluid that also exhibits elastic behaviors: droplets are increasingly deformed with increasing elasticity of the continuous phase. The overall understanding in the model multiphase microsystem will facilitate the use of a droplet-based approach for non-Newtonian multiphase applications ranging from energy to biomedical sciences.

  4. Droplet Deformation Prediction with the Droplet Deormation and Break Up Model (DDB)

    NASA Technical Reports Server (NTRS)

    Vargas, Mario

    2012-01-01

    The Droplet Deformation and Breakup Model was used to predict deformation of droplets approaching the leading edge stagnation line of an airfoil. The quasi-steady model was solved for each position along the droplet path. A program was developed to solve the non-linear, second order, ordinary differential equation that governs the model. A fourth order Runge-Kutta method was used to solve the equation. Experimental slip velocities from droplet breakup studies were used as input to the model which required slip velocity along the particle path. The center of mass displacement predictions were compared to the experimental measurements from the droplet breakup studies for droplets with radii in the range of 200 to 700 mm approaching the airfoil at 50 and 90 m/sec. The model predictions were good for the displacement of the center of mass for small and medium sized droplets. For larger droplets the model predictions did not agree with the experimental results.

  5. Mechanism of Supercooled Water Droplet Breakup near the Leading Edge of an Airfoil

    NASA Technical Reports Server (NTRS)

    Veras-Alba, Belen; Palacios, Jose; Vargas, Mario; Ruggeri, Charles; Bartkus, Tadas P.

    2017-01-01

    This work presents the results of an experimental study on supercooled droplet deformation and breakup near the leading edge of an airfoil. The results are compared to prior room temperature droplet deformation results to explore the effects of droplet supercooling. The experiments were conducted in the Adverse Environment Rotor Test Stand (AERTS) at The Pennsylvania State University. An airfoil model placed at the end of the rotor blades mounted onto the hub in the AERTS chamber was moved at speeds ranging between 50 and 80 m/sec. The temperature of the chamber was set at -20°C. A monotonic droplet generator was used to produce droplets that fell from above, perpendicular to the path of the airfoil. The supercooled state of the droplets was determined by measurement of the temperature of the drops at various locations below the droplet generator exit. A temperature prediction code was also used to estimate the temperature of the droplets based on vertical velocity and the distance traveled by droplets from the droplet generator to the airfoil stagnation line. High speed imaging was employed to observe the interaction between the droplets and the airfoil. The high speed imaging provided droplet deformation information as the droplet approached the airfoil near the stagnation line. A tracking software program was used to measure the horizontal and vertical displacement of the droplet against time. It was demonstrated that to compare the effects of water supercooling on droplet deformation, the ratio of the slip velocity and the initial droplet velocity must be equal. A case with equal slip velocity to initial velocity ratios was selected for room temperature and supercooled droplet conditions. The airfoil velocity was 60 m/s and the slip velocity for both sets of data was 40 m/s. In these cases, the deformation of the weakly supercooled and warm droplets did not present different trends. The similar behavior for both environmental conditions indicates that water

  6. Additive empirical parametrization and microscopic study of deuteron breakup

    NASA Astrophysics Data System (ADS)

    Avrigeanu, M.; Avrigeanu, V.

    2017-02-01

    Comparative assessment of the total breakup proton-emission cross sections measured for 56 MeV deuteron interaction with target nuclei from 12C to 209Bi, with an empirical parametrization and recently calculated microscopic neutron-removal cross sections was done at the same time with similar data measured at 15, 25.5, 70, and 80 MeV. Comparable mass dependencies of the elastic-breakup (EB) cross sections provided by the empirical parametrization and the microscopic results have been also found at the deuteron energy of 56 MeV, while the assessment of absolute-values variance up to a factor of two was not possible because of the lack of EB measurements at energies higher than 25.5 MeV. While the similarities represent an additional validation of the microscopic calculations, the cross-section difference should be considered within the objectives of further measurements.

  7. Thermally induced breakup of metallic nanowires: experiment and theory.

    PubMed

    Schnedlitz, Martin; Lasserus, Maximilian; Knez, Daniel; Hauser, Andreas W; Hofer, Ferdinand; Ernst, Wolfgang E

    2017-04-05

    We present time-resolved transmission electron microscopy studies of the degradation of Au, Ag, Cu and Ni nanowires deposited on a heated support. The wires are grown under fully inert conditions in superfluid helium droplets and deposited onto amorphous carbon. The inherent stability of these pristine metal nanowires with diameters below 10 nm is investigated in the absence of any stabilizers, templates or solvents. The phenomenon of Rayleigh-breakup, a consequence of diffusion processes along the wire surfaces, is analysed in situ via scans over time and support temperature. Our experimental efforts are combined with simulations based on a novel model featuring a cellular automaton to emulate surface diffusion. Based on this model, correlations between the material parameters and actual breakup behaviour are studied.

  8. Breakup reaction study of the Brunnian nucleus {sup 10}C

    SciTech Connect

    Curtis, N.; Ashwood, N. I.; Clarke, N. M.; Freer, M.; Haigh, P. J.; Ziman, V.; Achouri, N. L.; Laurent, B.; Orr, N. A.; Bohlen, H. G.; Catford, W. N.; Patterson, N. P.; Thomas, J. S.; Soic, N.

    2008-02-15

    The structure and 2{alpha}+2p breakup of {sup 10}C, the only known Brunnian nucleus, has been studied at 33.3 MeV/nucleon. The breakup kinematics were used to reconstruct the {sup 10}C {yields} {sup 9}B +p,{sup 9}B {yields} {sup 8}Be +p,{sup 8}Be {yields}{alpha}+{alpha} and {sup 10}C {yields} {sup 6}Be +{alpha},{sup 6}Be {yields} {sup 5}Li +p,{sup 5}Li {yields}{alpha}+p decay paths. Proton emission was seen to be favored. The decay of excited states at E{sub x}=4.20,5.31, and 6.74 MeV was observed. The previously unobserved state at 4.20 MeV may correspond to a J{sup {pi}}=0{sup +}{alpha}+2p+{alpha} cluster structure.

  9. Viscous Particle Breakup within a Cooling Nuclear Fireball

    SciTech Connect

    Wilkinson, J. T.; Knight, K. B.; Dai, Z.; Ramon, C. E.; Reid, J. D.

    2016-10-04

    Following the surface detonation of a nuclear weapon, the Earth’s crust and immediate surroundings are drawn into the fireball and form melts. Fallout is formed as these melts incorporate radioactive material from the bomb vapor and cool rapidly. The resultant fallout plume and dispersion of radioactive contamination is a function of several factors including weather patterns and fallout particle shapes and size distributions. Accurate modeling of the size distributions of fallout forms an important data point for dispersion codes that calculate the aerial distribution of fallout. While morphological evidence for aggregation of molten droplets is well documented in fallout glass populations, the breakup of these molten droplets has not been similarly studied. This study documents evidence that quenched fallout populations preserve evidence of molten breakup mechanisms.

  10. The Soviet Breakup and U.S. Foreign Policy.

    ERIC Educational Resources Information Center

    Lynch, Allen

    1991-01-01

    This issue of a quarterly publication on world affairs explores the historical significance of the disintegration of the Soviet Union and the implication for U.S. foreign policy. With the breakup of the USSR in 1990-91, Russia for the first time this century does not have control over the non-Russian nations of its former empire in Central Asia,…

  11. An analysis of the 2016 Hitomi breakup event

    NASA Astrophysics Data System (ADS)

    Flegel, Sven; Bennett, James; Lachut, Michael; Möckel, Marek; Smith, Craig

    2017-04-01

    The breakup of Hitomi (ASTRO-H) on 26 March 2016 is analysed. Debris from the fragmentation is used to estimate the time of the event by propagating backwards and estimating the close approach with the parent object. Based on this method, the breakup event is predicted to have occurred at approximately 01:42 UTC on 26 March 2016. The Gaussian variation of parameters equations based on the instantaneous orbits at the predicted time of the event are solved to gain additional insight into the on-orbit position of Hitomi at the time of the event and to test an alternate approach of determining the event epoch and location. A conjunction analysis is carried out between Hitomi and all catalogued objects which were in orbit around the estimated time of the anomaly. Several debris objects have close approaches with Hitomi; however, there is no evidence to support the breakup was caused by a catalogued object. Debris from both of the largest fragmentation events—the Iridium 33-Cosmos 2251 conjunction in 2009 and the intentional destruction of Fengyun 1C in 2007—is involved in close approaches with Hitomi indicating the persistent threat these events have caused in subsequent space missions. To quantify the magnitude of a potential conjunction, the fragmentation resulting from a collision with the debris is modelled using the EVOLVE-4 breakup model. The debris characteristics are estimated from two-line element data. This analysis is indicative of the threat to space assets that mission planners face due to the growing debris population. The impact of the actual event to the environment is investigated based on the debris associated with Hitomi which is currently contained in the United States Strategic Command's catalogue. A look at the active missions in the orbital vicinity of Hitomi reveals that the Hubble Space Telescope is among the spacecraft which may be immediately affected by the new debris.[Figure not available: see fulltext.

  12. Semiclassical calculations of observable cross sections in breakup reactions

    SciTech Connect

    Marta, H. D.; Canto, L. F.; Donangelo, R.

    2008-09-15

    We develop a semiclassical procedure to calculate breakup reaction products' angular and energy distributions in the laboratory frame of reference. The effects of the Coulomb and nuclear interaction potentials on the classical trajectories, as well as bound-bound, bound-continuum, and continuum-continuum couplings, are included. As an example we consider the {sup 8}B+{sup 58}Ni system at E{sub lab}=26 MeV and find very good agreement with the available experimental data.

  13. Peregrine soliton generation and breakup in standard telecommunications fiber.

    PubMed

    Hammani, Kamal; Kibler, Bertrand; Finot, Christophe; Morin, Philippe; Fatome, Julien; Dudley, John M; Millot, Guy

    2011-01-15

    We present experimental and numerical results showing the generation and breakup of the Peregrine soliton in standard telecommunications fiber. The impact of nonideal initial conditions is studied through direct cutback measurements of the longitudinal evolution of the emerging soliton dynamics and is shown to be associated with the splitting of the Peregrine soliton into two subpulses, with each subpulse itself exhibiting Peregrine soliton characteristics. Experimental results are in good agreement with simulations.

  14. Study of Liquid Breakup Process in Solid Rocket Motors

    DTIC Science & Technology

    2014-01-01

    Averaged Navier-Stokes code ( URANS ) to investigate the interaction of the liquid film flow with the gas flow, and analyzed the breakup process for...unsteady-flow Reynolds-Averaged Navier-Stokes code ( URANS ) to investigate the interaction of the liquid film flow with the gas flow, and analyzed the...predict the flows by solving the unsteady Reynolds-Averaged Navier-Stokes ( URANS ) equations16. The system of equations was solved in an Eulerian multi

  15. The Soviet Breakup and U.S. Foreign Policy.

    ERIC Educational Resources Information Center

    Lynch, Allen

    1991-01-01

    This issue of a quarterly publication on world affairs explores the historical significance of the disintegration of the Soviet Union and the implication for U.S. foreign policy. With the breakup of the USSR in 1990-91, Russia for the first time this century does not have control over the non-Russian nations of its former empire in Central Asia,…

  16. Beam break-up in the two beam accelerator

    SciTech Connect

    Whittum, D.H.; Travish, G.A.; Sessler, A.M.; Craig, G.D.; DeFord, J.F.

    1989-03-01

    We have studied numerically beam break-up (BBU) in the drive beam of a Two-Beam Accelerator (TBA), using transverse wakes calculated numerically using the AMOS Code. We examine only cumulative BBU due to the wake of the linear induction accelerator cavities. We do not consider regenerative BBU due to the relativistic klystron (RK) cavities. We find growth lengths of order /approximately/100 m for typical parameters. 14 refs., 2 figs., 1 tab.

  17. Beam breakup integral measurement on high-power laser chains.

    PubMed

    Villate, Denis; Blanchot, Nathalie; Rouyer, Claude

    2007-03-01

    We experimentally demonstrate the efficiency of a single-shot method to measure the beam breakup integral (B) accumulated across a high power chain. The technique uses spectrally shaped strongly chirped femtosecond pulses and takes advantage of time-to-spectral coupling generated by nonlinear effects. We performed B measurements on regenerative amplifiers (Ti:sapphire) and on the ALISE 200 J facility currently installed at CEA-CESTA (France).

  18. Radial electron-beam-breakup transit-time oscillator

    SciTech Connect

    Mostrom, M.A.; Kwan, T.J.T.

    1995-01-01

    A new radially-driven electron-beam-breakup transit-time oscillator has been investigated analytically and through computer simulation as a compact low-impedance high-power microwave generator. In a 1MV, 50kA device 35cm in radius and 15cm long, with no external magnetic field, 5GW of extracted power and a growth rate of 0.26/ns have been observed. Theoretical maximum efficiencies are several times higher.

  19. The Effect of Crustal Strength on Volcanism During Continental Breakup

    NASA Astrophysics Data System (ADS)

    Armitage, J. J.; Petersen, K. D.; Perez-Gussinye, M.; Collier, J.; Pik, R.

    2015-12-01

    Segmentation is a fundamental property of rifted margins which is thought to be inherited from pre-breakup lithospheric structure. The volume of melt emplaced during rifting typically varies across these segments. Notable examples are the Gulf of California, break-up in the South Atlantic, and the Afar depression. For example in Afar there is a clear north south transition from break-up in the Erta Ale segment, where there is localised young (<1 Ma) volcanism, to the Dabbahu segment where there is the 4-1 Ma Stratoid volcanic series and distributed faulting. Along the Namibian and conjugate Argentinian margin there is evidence that surface area of seaward dipping reflectors change across segments. Such lateral changes in volcanism over a relatively short spatial scale are hard to explain by change in mantle temperature. We will demonstrate that crustal strength places a crucial control on the volume and composition of melt generated during break-up. We have compared models of extension with a weaker and strong lower crust based on observed rock rheologies. Melt composition and volume is found to be a function of the lower crustal rheology as it effects the shape of the melt zone during extension. By comparing a suite models we find that Afar volcanism can be matched by models with both a weak or strong lower crust. If however the crust is weaker then the equivalent volume and composition is created with less crustal thinning but over a greater period of time. The difference in time required to generate significant volcanic rock may explain the change in surface area of sub-areal volcanism in both Afar, where there is a transition of strong to weak crust from Erta Ale to Dabbahu, and off-shore Namibia. Lateral variation in volcanism between segments may therefore be fundamentally controlled by the crust.

  20. Thermocapillary-induced breakup of molten cladding films

    SciTech Connect

    Henkel, P.R.

    1987-06-01

    The fragmentation of molten cladding films into rivulets and single waves is investigated. This problem is especially relevant to liquid-metal fast breeder reactor safety analysis because of its impact on the flow regime of the clad metal. Among other effects, various instabilities may contribute to film breakup. In the axial direction, the Kelvin-Helmholtz instability can arise. As the Sandia transient axial relocation experiments frequently exhibit, an azimuthal fragmentation process also occurs. Consequently, another instability due to thermocapillarity is proposed.

  1. Study of Liquid Breakup Process in Solid Rocket Motor Nozzle

    DTIC Science & Technology

    2016-02-16

    a higher Weber Number relates to higher breakup of the two-phase flow. 15. SUBJECT TERMS N /A 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...Unclassified SAR 31 19b. TELEPHONE NO (include area code) N /A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18...temperature correlated density parameter = Volume fraction of n th phase in VOF model β = Thermal expansion coefficient = Kronecker delta = 3rd

  2. Transverse liquid fuel jet breakup, burning, and ignition

    SciTech Connect

    Li, H.

    1990-01-01

    An analytical/numerical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion first proposed by Schetz, et al. (1980). Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, have been used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic crossflow. Typical flame structures and concentration profiles have been calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integrated reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

  3. NAVSPASUR orbital processing for satellite break-up events

    NASA Technical Reports Server (NTRS)

    Schumacher, Paul W., Jr.

    1991-01-01

    Satellite breakups via explosion or collision can instantly increase the trackable orbiting population by up to several hundred objects, temporarily perturbing the routine space surveillance operations at U.S. Space Command (USSPACWCOM) and the Naval Space Surveillance Center (NAVSPASUR). This paper is a survey of some of the procedures and techniques used by NAVSPASUR to respond to such events. First, the overall data flow at NAVSPASUR is described highlighting the places at which human analysts may intervene with special processing. So-called manual intervention is required in a variety of non-nominal situations, including breakups. Second, a description is given of some of the orbital analysis and other software tools available to NAVSPASUR analysts. These tools were developed in-house over the past thirty years and can be employed in a highly flexible manner. The basic design philosophy for these tools was to implement simple concepts as efficiently as possible and to allow the analyst maximum use of his personal expertise. Finally, several historical breakup scenarios are discussed briefly. These scenarios provide examples of the types of questions that are fairly easy to answer in the present operational environment, as well as examples of questions that are very difficult to answer.

  4. Breakup length of harmonically stimulated capillary jets - theory and experiments

    NASA Astrophysics Data System (ADS)

    Garcia Garcia, Francisco Javier; Gonzalez Garcia, Heliodoro; Castrejon-Pita, Jose Rafael; Castrejon-Pita, Alfonso Arturo

    2014-11-01

    A stream of liquid breaks up into several drops by the action of surface tension. Capillary breakup forms the basis of some modern digital technologies, especially inkjet printing (including 3D manufacturing). Therefore, the control and prediction of the breakup length of harmonically modulated capillary jets is of great importance, in particular in Continuous InkJet systems (CIJ). However, a theoretical model that rigorously takes into account the physical characteristics of the system, and that properly describes this phenomenon did not exist until now. In this work we present a simple transfer function, derived from first principles, that accurately predicts the experimentally obtained breakup lengths of pressure-modulated capillary jets. No fitting parameters are necessary. A detailed description of the theoretical model and experimental setup will be presented. Spanish government (FIS2011-25161), Junta de Andalucia (P09-FQM-4584 and P11-FQM-7919), EPSRC-UK (EP/H018913/1), Royal Society and John Fell Fund (OUP).

  5. Resonant breakup of {sup 19}C on a proton target

    SciTech Connect

    Crespo, R.; Rodriguez-Gallardo, M.; Moro, A. M.; Deltuva, A.; Cravo, E.; Fonseca, A. C.

    2011-05-15

    The resonant breakup of {sup 19}C on a proton target at 70 MeV/nucleon is analyzed using Faddeev-Alt, Grassberger, Sandhas (Faddeev-AGS) and continuum-discretized coupled-channels (CDCC) reaction frameworks, where in both cases a three-body model ({sup 18}C+n+p) for the reaction is considered. Taking a {sup 18}C + p potential from a global nucleon-nucleus parametrization and a L-independent Gaussian proton-neutron potential, both methods provide very similar results for the calculated observables. However, when this simplified proton-neutron potential is replaced by the more realistic CD-Bonn potential, the breakup cross section, calculated with the Faddeev AGS formalism, decreases by almost one order of magnitude, largely underestimating the experimental data. From this calculation, we conclude that, within a core + valence neutron model, the single-particle mechanism gives a negligible contribution to the calculated resonant breakup and therefore core-excitation mechanisms should be taken into account.

  6. Examining of the Collision Breakup Model between Geostationary Orbit Objects

    NASA Astrophysics Data System (ADS)

    Hata, Hidehiro; Hanada, Toshiya; Akahoshi, Yasuhiro; Yasaka, Tetsuo; Harada, Shoji

    This paper will examine the applicability of the hypervelocity collision model included in the NASA standard breakup model 2000 revision to low-velocity collisions possible in space, especially in the geosynchronous regime. The analytic method used in the standard breakup model will be applied to experimental data accumulated through low-velocity impact experiments performed at Kyushu Institute of Technology at a velocity about 300m/s and 800m/s. The projectiles and target specimens used were aluminum solid balls and aluminum honeycomb sandwich panels with face sheets of carbon fiber reinforced plastic, respectively. Then, we have found that a kind of lower boundary exists on fragment area-to-mass distribution at a smaller characteristic length range. This paper will describe the theoretical derivation of lower boundary and propose another modification on fragment area-to-mass distribution and it will conclude that the hypervelocity collision model in the standard breakup model can be applied to low-velocity collisions possible with some modifications.

  7. A model of plate kinematics in Gondwana breakup

    NASA Astrophysics Data System (ADS)

    Eagles, Graeme; König, Matthias

    2008-05-01

    An accurate model of relative plate motions in Gondwana breakup is based on visual fitting of seafloor isochrons and fracture zones (FZ) from the Riiser-Larsen Sea and Mozambique Basin. Used predictively, the model precisely locates kinematic markers in the West Somali Basin, which allows the conclusion that the spreading centres in the West Somali and Mozambique basins and the Riiser-Larsen Sea formed parts of the boundary between the same two plates. The locations of FZ and less well-defined isochrons from neighbouring regions are also consistent with their formation on other lengths of this same boundary and with its relocation from the West Somali Basin and northern Natal Valley to the West Enderby Basin and Lazarev Sea during chron M10n. Small independently moving plates thus played no role in the breakup of this core part of Gondwana. In an inversion procedure, the data from these areas yield more precise finite rotations that describe the history of the two plates' separation. Breakup is most simply interpreted to have occurred in coincidence with Karoo volcanism, and a reconstruction based on the rotations shows the Lebombo and Mateke-Sabi monoclines and the Mozambique and Astrid ridges as two sets of conjugate volcanic margins. Madagascar's pre-drift position can be used as a constraint to reassess the positions of India and Sri Lanka in the supercontinent.

  8. The Fragmented Manihiki Plateau - Key Region for Understanding the Break-up of the "Super" Large Igneous Province Ontong Java Nui

    NASA Astrophysics Data System (ADS)

    Hochmuth, K.; Gohl, K.; Uenzelmann-Neben, G.; Werner, R.

    2014-12-01

    The Manihiki Plateau of the western Pacific is one of the world - wide greatest Large Igneous Province (LIP) on oceanic crust. It is assumed that the Manihiki Plateau was emplaced as the centerpiece of the "Super-LIP" Ontong Java Nui by multiple volcanic phases during the Cretaceous Magnetic Quiet Period. The subsequent break-up of Ontong Java Nui led to fragmentation of the Manihiki Plateau into three sub-plateaus, which all exhibit individual relicts of the "Super-LIP" break-up. We examine two deep crustal seismic refraction/wide-angle reflection profiles crossing the two largest sub-plateaus of the Manihiki Plateau, the Western Plateaus and the High Plateau. Modeling of P- and S-wave velocities reveals surprising differences in the crustal structure between the two sub-plateaus. Whereas the High Plateau shows a constant crustal thickness of 20 km, relicts of multiple volcanic phases and break-up features at its margins, the model of the Western Plateaus reveals a crustal thickness decreasing from 17 km to only 9 km. There is only little evidence of secondary phases of volcanic activity. The main upper crustal structure on the Western Plateaus consists of fault systems and sedimentary basins. We infer that the High Plateau experienced phases of strong secondary volcanism, and that tectonic deformation was limited to its edges. The Western Plateaus, on the contrary, were deformed by crustal stretching and underwent only little to no secondary volcanism. This indicates that the two main sub-plateaus of the Manihiki Plateau experienced a different geological history and have played their individual parts in the break-up history of Ontong Java Nui.

  9. Haglund's Deformity

    MedlinePlus

    ... deformity is often called “pump bump” because the rigid backs of pump-style shoes can create pressure ... when walking. In fact, any shoes with a rigid back, such as ice skates, men’s dress shoes ...

  10. Contracture deformity

    MedlinePlus

    Deformity - contracture ... Contracture can be caused by any of the following: Brain and nervous system disorders, such as cerebral ... Follow your health care provider's instructions for treating contracture at home. Treatments may include: Doing exercises and ...

  11. Spinal deformity.

    PubMed

    Bunnell, W P

    1986-12-01

    Spinal deformity is a relatively common disorder, particularly in teenage girls. Early detection is possible by a simple, quick visual inspection that should be a standard part of the routine examination of all preteen and teenage patients. Follow-up observation will reveal those curvatures that are progressive and permit orthotic treatment to prevent further increase in the deformity. Spinal fusion offers correction and stabilization of more severe degrees of scoliosis.

  12. A Numerical Analysis of Droplet Breakup in Asymmetric T-Junctions with Different Outlet Pressure Gradients

    NASA Astrophysics Data System (ADS)

    Cheng, Way Lee; Han, Arum; Sadr, Reza

    2016-11-01

    Droplet splitting is the breakup of a parent droplet into two or more daughter droplets of desired sizes. It is done to improve production efficiency and investigational capacity in microfluidic devices. Passive splitting is the breakup of droplets into precise volume ratios at predetermined locations without external power sources. In this study, a 3-D simulation was conducted using the Volume-of-Fluid method to analysis the breakup process of a droplet in asymmetric T-junctions with different outlet arm lengths. The arrangement allows a droplet to be split into two smaller droplets of different sizes, where the volumetric ratio of the daughter droplets depends on the length ratios of the outlet arms. The study identified different breakup regimes such as primary, transition, bubble and non-breakup under different flow conditions and channel configurations. Furthermore, a close analysis to the primary breakup regimes were done to determine the breakup mechanisms at various flow conditions. The analysis show that the breakup mechanisms in asymmetric T-junctions is different than a regular split. A pseudo-phenomenological model for the breakup criteria was presented at the end. The model was an expanded version to a theoretically derived model for the symmetric droplet breakup. The Qatar National Research Fund (a member of the Qatar Founda- tion), under Grant NPRP 5-671-2-278, supported this work.

  13. Rear-Surface Deformation of a Water Drop in Aero-Breakup of Shear Mode

    NASA Astrophysics Data System (ADS)

    Yi, Xiang-Yu; Zhu, Yu-Jian; Yang, Ji-Ming; Wang, Tun; Sun, Ming-Yu

    2017-08-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 11102204, 11572313 and 11621202, and the Natural Science Foundation of Anhui Province under Grant No 1608085MA16.

  14. Deformation and Breakup of Stretching Liquid Bridges Held Captive Between Unequal Disks

    NASA Astrophysics Data System (ADS)

    Panditaratne, Jayanta C.; Schreiweis, Amanda L.; Basaran, Osman A.

    1999-11-01

    In industrial processes including gravure coating, liquid atomization, and pin-tools used in genomic analysis, threads of liquid are stretched and broken. A convenient setup for studying the dynamics of stretching liquid threads is the liquid bridge, which is a volume of liquid held captive between two solid disks. Although the dynamics of stretching bridges with equal disks have been extensively studied, studies of stretching bridges with unequal disks are in their infancy. This paper reports the results of a combined computational and experimental study, the aim of which is to remedy the aforementioned deficiency. The computations entail solution of both the full set of governing two-dimensional (2-d) equations and a simpler set of one-dimensional (1-d) equations based on slender-jet theory. The experiments use high-speed imaging with dual imagers that focus on both the global and local features of interface rupture. The limitations of the 1-d model are brought out by comparison of its predictions with the 2-d predictions and measurements.

  15. Supercontinental inheritance and its influence on supercontinental breakup: The Central Atlantic Magmatic Province and the breakup of Pangea

    NASA Astrophysics Data System (ADS)

    Whalen, Lisa; Gazel, Esteban; Vidito, Christopher; Puffer, John; Bizimis, Michael; Henika, William; Caddick, Mark J.

    2015-10-01

    The Central Atlantic Magmatic Province (CAMP) is the large igneous province (LIP) that coincides with the breakup of the supercontinent Pangea. Major and trace element data, Sr-Nd-Pb radiogenic isotopes, and high-precision olivine chemistry were collected on primitive CAMP dikes from Virginia (VA). These new samples were used in conjunction with a global CAMP data set to elucidate different mechanisms for supercontinent breakup and LIP formation. On the Eastern North American Margin, CAMP flows are found primarily in rift basins that can be divided into northern or southern groups based on differences in tectonic evolution, rifting history, and supercontinental inheritance. Geochemical signatures of CAMP suggest an upper mantle source modified by subduction processes. We propose that the greater number of accretionary events, or metasomatism by sediment melts as opposed to fluids on the northern versus the southern Laurentian margin during the formation of Pangea led to different subduction-related signatures in the mantle source of the northern versus southern CAMP lavas. CAMP samples have elevated Ni and low Ca in olivine phenocrysts indicating a significant pyroxenite component in the source, interpreted here as a result of subduction metasomatism. Different collisional styles during the Alleghanian orogeny in the North and South may have led to the diachroneity of the rifting of Pangea. Furthermore, due to a low angle of subduction, the Rheic Plate may have underplated the lithosphere then delaminated, triggering both the breakup of Pangea and the formation of CAMP.

  16. On the breakup of an air bubble injected into a fully developed turbulent flow. Part 1. Breakup frequency

    NASA Astrophysics Data System (ADS)

    Martínez-Bazán, C.; Montañés, J. L.; Lasheras, J. C.

    1999-12-01

    The transient evolution of the bubble-size probability density functions resulting from the breakup of an air bubble injected into a fully developed turbulent water ow has been measured experimentally using phase Doppler particle sizing (PDPA) and image processing techniques. These measurements were used to determine the breakup frequency of the bubbles as a function of their size and of the critical diameter Dc defined as Dc = 1.26 ([sigma]/[rho])3/5[epsilon][minus sign]2/5, where [epsilon] is the rate of dissipation per unit mass and per unit time of the underlying turbulence. A phenomenological model is proposed showing the existence of two distinct bubble size regimes. For bubbles of sizes comparable to Dc, the breakup frequency is shown to increase as ([sigma]/[rho])[minus sign]2/5[epsilon][minus sign]3/5 [surd radical]D/Dc[minus sign]1, while for large bubbles whose sizes are greater than 1.63Dc, it decreases with the bubble size as [epsilon]1/3D[minus sign]2/3. The model is shown to be in good agreement with measurements performed over a wide range of bubble sizes and turbulence intensities.

  17. Simulations of insonated contrast agents: Saturation and transient break-up

    NASA Astrophysics Data System (ADS)

    Tsigklifis, Kostas; Pelekasis, Nikos A.

    2013-03-01

    Under insonation contrast agents are known to perform nonlinear pulsations and deform statically, in the form of buckling, or dynamically via parametric mode excitation, and often exhibit jetting and break-up like bubbles without coating. Boundary element simulations are performed in the context of axisymmetry in order to establish the nonlinear evolution of these patterns. The viscoelastic stresses that develop on the coating form the dominant force balance tangentially to the shell-liquid interface, whereas the dynamic overpressure across the shell balances viscoelastic stresses in the normal direction. Strain softening and strain hardening behavior is studied in the presence of shape instabilities for various initial conditions. Simulations recover the pattern of static buckling, subharmonic/harmonic excitation, and dynamic buckling predicted by linear stability. Preferential mode excitation during compression is obtained supercritically for strain softening phospholipid shells while the shell regains its sphericity at expansion. It is a result of energy transfer between the emerging unstable modes and the radial mode, eventually leading to saturated oscillations of shape modes accompanied by asymmetric radial pulsations in favor of compression. Strain softening shells are more prone to sustain saturated pulsations due to the mechanical behavior of the shell. As the sound amplitude increases and before the onset of dynamic buckling, both types of shells exhibit transient break-up via unbalanced growth of a number of unstable shape modes. The effect of pre-stress in lowering the amplitude threshold for shape mode excitation is captured numerically and compared against the predictions of linear stability analysis. The amplitude interval for which sustained shape oscillations are obtained is extended, in the presence of pre-stress, by switching from a strain softening constitutive law to a strain hardening one once the shell curvature increases beyond a certain

  18. 3D imaging of the rifting and breakup west of Spain and the nature of the S detachment

    NASA Astrophysics Data System (ADS)

    Reston, T. J.; Lymer, G.; Cresswell, D.; Stevenson, C.; Sawyer, D. S.; Bull, J. M.; Minshull, T. A.; Ranero, C. R.; Shillington, D. J.

    2016-12-01

    The west Galicia margin (NW Spain) is a magma-poor margin with limited sedimentary cover, providing ideal conditions to study the processes of continental extension and break-up through seismic imaging. In 2013, we collected a 65km x 20km 3D multi-channel seismic dataset extending from the edge of the Galicia Bank over the feather edge of the continental crust to beyond the Peridotite Ridge to the west. The volume has been processed through to 3D prestack time migration and 3D depth conversion and provides 3D images of the hyper-extended continental crust, consisting of well-defined but internally intensely deformed rotated faults blocks with associated syn-kinematic sedimentary wedges. The rotated fault blocks contain possible low-angle normal faults that in places appear to define and elsewhere to offset top basement; we interpret them as early faults that predate the formation of the fault blocks. The early faults are in places cut and offset by the later block-bounding faults that appear to detach downwards onto a bright reflection, the S reflector, a detachment fault and locally the crust-mantle boundary. S is corrugated on both depth and time structure maps, with the corrugations sweeping in an arc from E-W proximally to ESE-WNW towards the ocean. We interpret the corrugations as forming during slip on S and representing the displacement (and hence extension) direction on the detachment leading to breakup. Early synrift sediment within the most recent faults blocks are intensely deformed, representing the internal deformation of the fault blocks. However, in places simple synrift wedges can be seen to thicken towards the block-bounding faults. The angular relationship of the top of these wedges to the block-bounding faults demonstrates that they were deposited during slip on the faults and low-angle slip on the underlying S detachment. Although beneath the continental crust S appears continuous and shows only minor distortion in the vicinity of the block

  19. MP-Align: alignment of metabolic pathways

    PubMed Central

    2014-01-01

    Background Comparing the metabolic pathways of different species is useful for understanding metabolic functions and can help in studying diseases and engineering drugs. Several comparison techniques for metabolic pathways have been introduced in the literature as a first attempt in this direction. The approaches are based on some simplified representation of metabolic pathways and on a related definition of a similarity score (or distance measure) between two pathways. More recent comparative research focuses on alignment techniques that can identify similar parts between pathways. Results We propose a methodology for the pairwise comparison and alignment of metabolic pathways that aims at providing the largest conserved substructure of the pathways under consideration. The proposed methodology has been implemented in a tool called MP-Align, which has been used to perform several validation tests. The results showed that our similarity score makes it possible to discriminate between different domains and to reconstruct a meaningful phylogeny from metabolic data. The results further demonstrate that our alignment algorithm correctly identifies subpathways sharing a common biological function. Conclusion The results of the validation tests performed with MP-Align are encouraging. A comparison with another proposal in the literature showed that our alignment algorithm is particularly well-suited to finding the largest conserved subpathway of the pathways under examination. PMID:24886436

  20. Girder Alignment Plan

    SciTech Connect

    Wolf, Zackary; Ruland, Robert; LeCocq, Catherine; Lundahl, Eric; Levashov, Yurii; Reese, Ed; Rago, Carl; Poling, Ben; Schafer, Donald; Nuhn, Heinz-Dieter; Wienands, Uli; /SLAC

    2010-11-18

    The girders for the LCLS undulator system contain components which must be aligned with high accuracy relative to each other. The alignment is one of the last steps before the girders go into the tunnel, so the alignment must be done efficiently, on a tight schedule. This note documents the alignment plan which includes efficiency and high accuracy. The motivation for girder alignment involves the following considerations. Using beam based alignment, the girder position will be adjusted until the beam goes through the center of the quadrupole and beam finder wire. For the machine to work properly, the undulator axis must be on this line and the center of the undulator beam pipe must be on this line. The physics reasons for the undulator axis and undulator beam pipe axis to be centered on the beam are different, but the alignment tolerance for both are similar. In addition, the beam position monitor must be centered on the beam to preserve its calibration. Thus, the undulator, undulator beam pipe, quadrupole, beam finder wire, and beam position monitor axes must all be aligned to a common line. All relative alignments are equally important, not just, for example, between quadrupole and undulator. We begin by making the common axis the nominal beam axis in the girder coordinate system. All components will be initially aligned to this axis. A more accurate alignment will then position the components relative to each other, without incorporating the girder itself.

  1. Coulomb barrier penetrability in the 11Be + 208Pb breakup reaction

    NASA Astrophysics Data System (ADS)

    Mukeru, B.; Lekala, M. L.; Rampho, G. J.

    2015-08-01

    We use the continuum discretized coupled channels method to study the 11Be+208Pb breakup reaction. We investigate the effects of the continuum-continuum couplings (ccc) on the breakup cross sections. We find that high partial waves strengthen the ccc. Using the breakup cross sections of this reaction, we analyze the penetrability of the Coulomb barrier and show that this penetrability is reduced when the ccc are included.

  2. Quaternary deformation

    SciTech Connect

    Brown, R.D. Jr.

    1990-01-01

    Displaced or deformed rock units and landforms record the past 2 m.y. of faulting, folding, uplift, and subsidence in California. Properly interpreted, such evidence provides a quantitative basis for predicting future earthquake activity and for relating many diverse structures and landforms to the 5 cm/yr of horizontal motion at the boundary between the North American and Pacific plates. Modern techniques of geologic dating and expanded research on earthquake hazards have greatly improved our knowledge of the San Andreas fault system. Much of this new knowledge has been gained since 1965, and that part which concerns crustal deformation during the past 2 m.y. is briefly summarized here.

  3. Correcting the beam centroid motion in an induction accelerator and reducing the beam breakup instability

    NASA Astrophysics Data System (ADS)

    Coleman, J. E.; Ekdahl, C. A.; Moir, D. C.; Sullivan, G. W.; Crawford, M. T.

    2014-09-01

    Axial beam centroid and beam breakup (BBU) measurements were conducted on an 80 ns FWHM, intense relativistic electron bunch with an injected energy of 3.8 MV and current of 2.9 kA. The intense relativistic electron bunch is accelerated and transported through a nested solenoid and ferrite induction core lattice consisting of 64 elements, exiting the accelerator with a nominal energy of 19.8 MeV. The principal objective of these experiments is to quantify the coupling of the beam centroid motion to the BBU instability and validate the theory of this coupling for the first time. Time resolved centroid measurements indicate a reduction in the BBU amplitude, ⟨ξ⟩, of 19% and a reduction in the BBU growth rate (Γ) of 4% by reducing beam centroid misalignments ˜50% throughout the accelerator. An investigation into the contribution of the misaligned elements is made. An alignment algorithm is presented in addition to a qualitative comparison of experimental and calculated results which include axial beam centroid oscillations, BBU amplitude, and growth with different dipole steering.

  4. Plate break-up geometry in SE-Afar

    NASA Astrophysics Data System (ADS)

    Geoffroy, Laurent; Le Gall, Bernard; Daoud, Mohamed

    2014-05-01

    New structural data acquired in Djibouti strongly support the view of a magma-rich to magma-poor pair of conjugate margins developed in SE Afar since at least 9 Ma. Our model is illustrated by a crustal-scale transect that emphasizes the role of a two-stage extensional detachment fault system, with opposing senses of motion through time. The geometry and kinematics of this detachment fault pattern are mainly documented from lavas and fault dip data extracted from remote sensing imagery (Landsat ETM+, and corresponding DEM), further calibrated by field observations. Although expressed by opposite fault geometries, the two successive extensional events evidenced here are part of a two-stage continental extensional tear-system associated with the ongoing propagation of the Aden-Tadjoura oceanic axis to the NW. A flip-flop evolution of detachment faults accommodating lithosphere divergence has recently been proposed for the development of the Indian Ocean and continental margins (Sauter et al., 2013). However, the SE Afar evolution further suggests a radical and sudden change in lithosphere behavior during extension, from a long-term and widespread magmatic stage to a syn-sedimentary break-up stage where mantle melting concentrates along the future oceanic axis. Of special interest is the fact that a late and rapid stage of non-magmatic extension led to break-up, whose geometry triggered the location of the break-up axis and earliest oceanic accretion. New structural data acquired in Djibouti strongly support the view of a magma-rich to magma-poor pair of conjugate margins developed in SE Afar since at least 9 Ma. Our model is illustrated by a crustal-scale transect that emphasizes the role of a two-stage extensional detachment fault system, with opposing senses of motion through time. The geometry and kinematics of this detachment fault pattern are mainly documented from lavas and fault dip data extracted from remote sensing imagery (Landsat ETM+, and corresponding

  5. Bag-breakup control of surface drag in hurricanes

    NASA Astrophysics Data System (ADS)

    Troitskaya, Yuliya; Zilitinkevich, Sergej; Kandaurov, Alexander; Ermakova, Olga; Kozlov, Dmitry; Sergeev, Daniil

    2016-04-01

    Air-sea interaction at extreme winds is of special interest now in connection with the problem of the sea surface drag reduction at the wind speed exceeding 30-35 m/s. This phenomenon predicted by Emanuel (1995) and confirmed by a number of field (e.g., Powell, et al, 2003) and laboratory (Donelan et al, 2004) experiments still waits its physical explanation. Several papers attributed the drag reduction to spume droplets - spray turning off the crests of breaking waves (e.g., Kudryavtsev, Makin, 2011, Bao, et al, 2011). The fluxes associated with the spray are determined by the rate of droplet production at the surface quantified by the sea spray generation function (SSGF), defined as the number of spray particles of radius r produced from the unit area of water surface in unit time. However, the mechanism of spume droplets' formation is unknown and empirical estimates of SSGF varied over six orders of magnitude; therefore, the production rate of large sea spray droplets is not adequately described and there are significant uncertainties in estimations of exchange processes in hurricanes. Herewith, it is unknown what is air-sea interface and how water is fragmented to spray at hurricane wind. Using high-speed video, we observed mechanisms of production of spume droplets at strong winds by high-speed video filming, investigated statistics and compared their efficiency. Experiments showed, that the generation of the spume droplets near the wave crest is caused by the following events: bursting of submerged bubbles, generation and breakup of "projections" and "bag breakup". Statistical analysis of results of these experiments showed that the main mechanism of spray-generation is attributed to "bag-breakup mechanism", namely, inflating and consequent blowing of short-lived, sail-like pieces of the water-surface film. Using high-speed video, we show that at hurricane winds the main mechanism of spray production is attributed to "bag-breakup", namely, inflating and

  6. An Analysis of Recent Major Breakups in the Low Earth Orbit Region

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Anz-Meador, P. D.

    2010-01-01

    Of the 4 recent major breakup events, the FY-1C ASAT test and the collision between Iridium 33 and Cosmos 2251 generated the most long-term impact to the environment. About half of the fragments will still remain in orbit at least 20 years after the breakup. The A/M distribution of the Cosmos 2251 fragments is well-described by the NASA Breakup Model. Satellites made of modern materials (such as Iridium 33), equipped with large solar panels, or covered with large MLI layers (such as FY-1C) may generated significant amount of high A/M fragments upon breakup.

  7. Observations of breakup processes of liquid jets using real-time X-ray radiography

    NASA Technical Reports Server (NTRS)

    Char, J. M.; Kuo, K. K.; Hsieh, K. C.

    1988-01-01

    To unravel the liquid-jet breakup process in the nondilute region, a newly developed system of real-time X-ray radiography, an advanced digital image processor, and a high-speed video camera were used. Based upon recorded X-ray images, the inner structure of a liquid jet during breakup was observed. The jet divergence angle, jet breakup length, and fraction distributions along the axial and transverse directions of the liquid jets were determined in the near-injector region. Both wall- and free-jet tests were conducted to study the effect of wall friction on the jet breakup process.

  8. The visibility of color breakup and a means to reduce it

    PubMed Central

    Johnson, Paul V.; Kim, Joohwan; Banks, Martin S.

    2014-01-01

    Color breakup is an artifact seen on displays that present colors sequentially. When the eye tracks a moving object on such a display, different colors land on different places on the retina, and this gives rise to visible color fringes at the object's leading and trailing edges. Interestingly, color breakup is also observed when the eye is stationary and an object moves by. Using a novel psychophysical procedure, we measured breakup both when viewers tracked and did not track a moving object. Breakup was somewhat more visible in the tracking than in the non-tracking condition. The video frames contained three subframes, one each for red, green, and blue. We spatially offset the green and blue stimuli in the second and third subframes, respectively, to find the values that minimized breakup. In the tracking and non-tracking conditions, spatial offsets of Δx/3 in the second subframe (where Δx is the displacement of the object in one frame) and 2Δx/3 in the third eliminated breakup. Thus, this method offers a way to minimize or even eliminate breakup whether the viewer is tracking or not. We suggest ways to implement the method with real video content. We also developed a color-breakup model based on spatiotemporal filtering in color-opponent pathways in early vision. We found close agreement between the model's predictions and the experimental results. The model can be used to predict breakup for a wide variety of conditions. PMID:25527148

  9. Lattice Boltzmann modeling and simulation of liquid jet breakup

    NASA Astrophysics Data System (ADS)

    Saito, Shimpei; Abe, Yutaka; Koyama, Kazuya

    2017-07-01

    A three-dimensional color-fluid lattice Boltzmann model for immiscible two-phase flows is developed in the framework of a three-dimensional 27-velocity (D3Q27) lattice. The collision operator comprises the D3Q27 versions of three suboperators: a multiple-relaxation-time (MRT) collision operator, a generalized Liu-Valocchi-Kang perturbation operator, and a Latva-Kokko-Rothman recoloring operator. A D3Q27 version of an enhanced equilibrium distribution function is also incorporated into this model to improve the Galilean invariance. Three types of numerical tests, namely, a static droplet, an oscillating droplet, and the Rayleigh-Taylor instability, show a good agreement with analytical solutions and numerical simulations. Following these numerical tests, this model is applied to liquid-jet-breakup simulations. The simulation conditions are matched to the conditions of the previous experiments. In this case, numerical stability is maintained throughout the simulation, although the kinematic viscosity for the continuous phase is set as low as 1.8 ×10-4 , in which case the corresponding Reynolds number is 3.4 ×103 ; the developed lattice Boltzmann model based on the D3Q27 lattice enables us to perform the simulation with parameters directly matched to the experiments. The jet's liquid column transitions from an asymmetrical to an axisymmetrical shape, and entrainment occurs from the side of the jet. The measured time history of the jet's leading-edge position shows a good agreement with the experiments. Finally, the reproducibility of the regime map for liquid-liquid systems is assessed. The present lattice Boltzmann simulations well reproduce the characteristics of predicted regimes, including varicose breakup, sinuous breakup, and atomization.

  10. Hard breakup of the deuteron into two {Delta} isobars

    SciTech Connect

    Granados, Carlos G.; Sargsian, Misak M.

    2011-05-15

    We study high-energy photodisintegration of the deuteron into two {Delta} isobars at large center of mass angles within the QCD hard rescattering model (HRM). According to the HRM, the process develops in three main steps: the photon knocks a quark from one of the nucleons in the deuteron; the struck quark rescatters off a quark from the other nucleon sharing the high energy of the photon; then the energetic quarks recombine into two outgoing baryons which have large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn{yields}{Delta}{Delta} scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. Calculations show that the angular distribution and the strength of the photodisintegration is mainly determined by the properties of the pn{yields}{Delta}{Delta} scattering. We predict that the cross section of the deuteron breakup to {Delta}{sup ++}{Delta}{sup -} is 4-5 times larger than that of the breakup to the {Delta}{sup +}{Delta}{sup 0} channel. Also, the angular distributions for these two channels are markedly different. These can be compared with the predictions based on the assumption that two hard {Delta} isobars are the result of the disintegration of the preexisting {Delta}{Delta} components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both {Delta}{sup ++}{Delta}{sup -} and {Delta}{sup +}{Delta}{sup 0} channels to be similar.

  11. Numerical simulation of drop breakup and coalescence with soluble

    NASA Astrophysics Data System (ADS)

    Cristini, Vittorio; Lowengrub, John; Zhou, Hua; Macosko, Chris

    2003-11-01

    In the processing of emulsions and polymer blends, the drop size distributions are determined by two coexisting processes: drop breakup and coalescence. Here we study the effects of surfactants, e.g. block copolymers, on these phenomena and on the shear and normal stress in dilute blends by direct numerical simulation. We use a newly developed 3D adaptive algorithm. A nonlinear equation of state for the surfactant is used and van der Waals forces, which are responsible for coalescence, are included in the numerical method. Surfactants are transported by convection-diffusion on the drop/matrix interface and between the interface and the bulk phases. Our accurate and robust numerical method features parallel computation and adaptive reconstruction of the finite element meshes describing the bulk phases and the interface. We find that surfactants affect strongly the breakup and coalescence mechanisms by introducing nonuniformities in surface tension. The related Marangoni (tangential) stresses at the interface greatly inhibit coalescence but in a nontrivial fashion. At small coverages of surfactant at the interface, the critical capillary number for coalescence (below which coalescence will occur) decreases. However, at larger coverages, the critical capillary number reaches a minimum and then increases again and tends to the value for clean (surfactant-free) interfaces. This behavior was first observed experimentally by Leal and coworkers. In this talk, we demonstrate that this behavior is a consequence of a nontrivial evolution of the Marangoni stresses. We also demonstrate that under certain conditions surfactants enhance coalescence by a totally different mechanism. This surfactant induced coalescence occurs when drops are separating and the surfactant-enriched highly-stretched drop tips interact. Finally, we present preliminary results of simulations that indicate that surfactants have a strong effect on the size of the fragments resulting from drop breakup

  12. Identical'' bands in normally-deformed nuclei

    SciTech Connect

    Garrett, J.D.; Baktash, C. ); Yu, C.H. . Dept. of Physics and Astronomy)

    1990-01-01

    Gamma-ray transitions energies in neighboring odd- and even-mass nuclei for normally-deformed nuclear configurations are analyzed in a manner similar to recent analyses for superdeformed states. The moment of inertia is shown to depend on pair correlations and the aligned angular momentum of the odd nucleon. The implications of this analysis for identical'' super-deformed bands are discussed. 26 refs., 9 figs.

  13. Radial electron-beam-breakup transit-time oscillator

    DOEpatents

    Kwan, Thomas J. T.; Mostrom, Michael A.

    1998-01-01

    A radial electron-beam-breakup transit-time oscillator (RBTO) provides a compact high power microwave generator. The RBTO includes a coaxial vacuum transmission line having an outer conductor and an inner conductor. The inner conductor defines an annular cavity with dimensions effective to support an electromagnetic field in a TEM.sub.00m mode. A radial field emission cathode is formed on the outer conductor for providing an electron beam directed toward the annular cavity electrode. Microwave energy is then extracted from the annular cavity electrode.

  14. Multifragment emission and the experimental characterization of breakup reactions

    SciTech Connect

    Martinez Heimann, D.; Pacheco, A. J.; Arazi, A.; Fernandez Niello, J. O.; Figueira, J. M.; Negri, A.; Capurro, O. A.; Carnelli, P.; Cardona, M. A.; Barbara, E. de; Fimiani, L.; Hojman, D. L.; Marti, G. V.

    2010-08-04

    The production of three or more particles in nuclear reactions is discussed in terms of physically meaningful variables for the description of the asymptotic exit-channel configuration. The emphasis is placed in a direct comparison between these basic variables obtained in a purely experimental way and the corresponding results of generic model calculations. Applications of this approach to a few examples of recent inclusive and exclusive measurements of breakup reactions in the {sup 6,7}Li+{sup 144}Sm systems are presented.

  15. Kinematic Model of River Ice Motion During Dynamic Breakup

    DTIC Science & Technology

    1993-09-01

    Texas: Gulf Publish- nal of Computational Physics, 101: 130-139. ing Co. Shen, H.T. and Y.C. Chen (1992) Lagrangian discrete Calkins , DJ. (1978...OTIC9 ~jjELECTE0 lV 919 3 AD-A273 141 * Kinematic Model of River Ice Motion During Dynamic Breakup Michael G . Ferrick, Patricia B. Weyrick and David...Bottom) Looking across the river during brash ice motion at about 1 m /s. (Photos by M . Ferrick.) For conversion of SI metric units to U.S./British

  16. Core excitation effects in the breakup of halo nuclei

    SciTech Connect

    Moro, A. M.; Diego, R. de; Lay, J. A.; Crespo, R.; Johnson, R. C.; Arias, J. M.; Gomez-Camacho, J.

    2012-10-20

    The role of core excitation in the structure and dynamics of two-body halo nuclei is investigated. We present calculations for the resonant breakup of {sup 11}Be on protons at an incident energy of 63.7 MeV/nucleon, where core excitation effects were shown to be important. To describe the reaction, we use a recently developed extension of the DWBA formalism which incorporates these core excitation effects within the no-recoil approximation. The validity of the no-recoil approximation is also examined by comparing with DWBA calculations which take into account core recoil. In addition, calculations with two different continuum representations are presented and compared.

  17. Breakup effects on alpha spectroscopic factors of 16O

    NASA Astrophysics Data System (ADS)

    Adhikari, S.; Basu, C.; Sugathan, P.; Jhinghan, A.; Behera, B. R.; Saneesh, N.; Kaur, G.; Thakur, M.; Mahajan, R.; Dubey, R.; Mitra, A. K.

    2017-01-01

    The triton angular distribution for the 12C(7Li,t)16O* reaction is measured at 20 MeV, populating discrete states of 16O. Continuum discretized coupled reaction channel calculations are used to to extract the alpha spectroscopic properties of 16O states instead of the distorted wave born approximation theory to include the effects of breakup on the transfer process. The alpha reduced width, spectroscopic factors and the asymptotic normalization constant (ANC) of 16O states are extracted. The error in the spectroscopic factor is about 35% and in that of the ANC about 27%.

  18. North Atlantic Margins: Case studies of Magmatic Continental Breakup

    NASA Astrophysics Data System (ADS)

    Eccles, J. D.; White, R. S.; Christie, P. A. F.

    2012-04-01

    Continental breakup between Europe and Greenland was accompanied by the rapid eruption of the > 1 million cubic kilometres of extruded basalts forming North Atlantic Igneous Province. With episodes of extension in the region dating back to the Devonian, rifting finally proceeded to full breakup and oceanic spreading in the Paleocene. Flood basalt units flowed up to 150 km over pre-existing sedimentary basins, discrete volcanic centres formed and intrusion into the thinned continental crust occurred. Marine seismic investigations utilising industry-leading seismic reflection imaging technologies and large deployments of ocean bottom seismometers across the Faroes and Hatton Bank margins have been used to better resolve margin structure and composition, improving our understanding of breakup processes. Seismic reflection imaging reveals sub-aerial and submarine seaward-dipping reflector sequences tracking the interplay of uplift (transient and permanent), crustal loading through extrusion and ongoing extension. Lower crustal reflectors, cross-cutting the continental fabric and interpreted as intrusions, are observed within the narrow continent-ocean transition. P-wave tomography of wide-angle reflections and refractions, recorded to offsets of up to ~200 km, reveals unusually thick oceanic crust with lower crustal velocities in excess of those expected for MORB compositions. High P-wave velocities are attributed to magnesium-rich compositions which, combined with the large oceanic crustal thickness, would be consistent with an elevated mantle temperature (~150°C higher than 'normal') at the time of breakup. Vp/Vs ratios derived from tomography of converted shear wave phases also support high magnesium melt composition. P-wave velocities and Vp/Vs ratios across the continent-ocean transition show a mixing trend between magnesium-rich gabbroic compositions (100% for oceanic crust) and compositions consistent with the Lewisian gneiss basement or Early Proterozoic

  19. Ballistic Imaging of Liquid Breakup Processes in Dense Sprays

    DTIC Science & Technology

    2009-06-24

    spray breakup in its entirety. Gas-phase flowfield dynamics can be captured via particle image velocimetry (PIV) and/or laser Doppler velocimetry... Coherent Legend Ti:Sapphire regenerative amplifier, seeded with a Spectra-Physics Tsunami Ti:Sapphire mode-locked laser generating 40 fs, 2.5 mJ pulses...scattering turbid media. Laser Phys. Lett., 3(9):464–7, 2006. [44] B. Kaldvee, A. Ehn, J. Bood, and M. Aldén. Development of a picosecond- LIDAR system

  20. Breakup of Bubbles or Drops by Capillary Waves Induced by Coalescence or Other Excitations

    NASA Astrophysics Data System (ADS)

    Zhang, Feng Hua; Taborek, Peter; Burton, Justin; Cheong Khoo, Boo; Thoroddsen, Siggi

    2012-02-01

    Capillary breakup of a bubble or drop by various excitations is ubiquitous in both nature and technology. Examples include coalescence with another bubble or drop, wetting on a solid surface, impact on a solid surface, detachment from a nozzle, or vibrations driven by acoustic, electrical, or magnetic fields. When the excitation ceases, capillary forces on the surface naturally drive the deformed bubble or drop to recover its spherical shape. However, when the viscosity is small, this recovery can lead to nonlinear oscillations of the interface and a singularity in the flow. Here we use high-speed imaging to investigate the coalescence of bubbles and drops of various sizes. In many cases, coalescence leads to pinch-off events and the formation of the satellite and sub-satellite. Our experiments use pressured xenon gas in glycerol/water mixtures so that the density ratio and viscosity ratio can be varied over many orders of magnitude. We characterize the generation, propagation, and convergence of capillary waves, the formation time and sizes of satellites, and the dynamics of two-fluid pinch-off as a function of the density ratio and viscosity ratio. The work shall benefit the wide-spread applications and fulfill the scientific and public curiosities.

  1. Marangoni stresses and drop breakup due to wall shear in a partially filled rotating cylinder

    NASA Astrophysics Data System (ADS)

    White, Andrew; Odesanya, Azeez; Ward, Thomas

    2015-11-01

    Drop deformation and breakup in a rotating cylinder partially filled with oil is studied. Experiments using a rotating cylinder are relatively new but we will demonstrate that they are analogous to studies involving tubes and other geometries. Surfactants are added to the drop phase in concentrations at and below the CMC while the rotation rate of the cylinder is varied. Of interest is the effect of interfacial surfactant transport on changes in oil film thickness, drop shape and the onset of tail streaming. Two Biot numbers comparing the importance of surfactant adsorption and desorption to convection of surfactant on the interface are estimated. As shown in previous work on drops and bubbles in tubes, the balance between surface convection, diffusion and adsorption can affect the placement of Marangoni stresses, resulting in thicker or thinner films than with clean surfaces. When surface convection is large, surfactant builds up at the tail and Marangoni stresses can lead to tail streaming when surface tensions are sufficiently small. Experimental results are compared to numerical simulations and to previous work on drops and bubbles in tubes. National Science Foundation (#1262718).

  2. Tidal alignment of galaxies

    SciTech Connect

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš E-mail: zvlah@stanford.edu

    2015-08-01

    We develop an analytic model for galaxy intrinsic alignments (IA) based on the theory of tidal alignment. We calculate all relevant nonlinear corrections at one-loop order, including effects from nonlinear density evolution, galaxy biasing, and source density weighting. Contributions from density weighting are found to be particularly important and lead to bias dependence of the IA amplitude, even on large scales. This effect may be responsible for much of the luminosity dependence in IA observations. The increase in IA amplitude for more highly biased galaxies reflects their locations in regions with large tidal fields. We also consider the impact of smoothing the tidal field on halo scales. We compare the performance of this consistent nonlinear model in describing the observed alignment of luminous red galaxies with the linear model as well as the frequently used 'nonlinear alignment model,' finding a significant improvement on small and intermediate scales. We also show that the cross-correlation between density and IA (the 'GI' term) can be effectively separated into source alignment and source clustering, and we accurately model the observed alignment down to the one-halo regime using the tidal field from the fully nonlinear halo-matter cross correlation. Inside the one-halo regime, the average alignment of galaxies with density tracers no longer follows the tidal alignment prediction, likely reflecting nonlinear processes that must be considered when modeling IA on these scales. Finally, we discuss tidal alignment in the context of cosmic shear measurements.

  3. Tidal alignment of galaxies

    SciTech Connect

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš

    2015-08-01

    We develop an analytic model for galaxy intrinsic alignments (IA) based on the theory of tidal alignment. We calculate all relevant nonlinear corrections at one-loop order, including effects from nonlinear density evolution, galaxy biasing, and source density weighting. Contributions from density weighting are found to be particularly important and lead to bias dependence of the IA amplitude, even on large scales. This effect may be responsible for much of the luminosity dependence in IA observations. The increase in IA amplitude for more highly biased galaxies reflects their locations in regions with large tidal fields. We also consider the impact of smoothing the tidal field on halo scales. We compare the performance of this consistent nonlinear model in describing the observed alignment of luminous red galaxies with the linear model as well as the frequently used "nonlinear alignment model," finding a significant improvement on small and intermediate scales. We also show that the cross-correlation between density and IA (the "GI" term) can be effectively separated into source alignment and source clustering, and we accurately model the observed alignment down to the one-halo regime using the tidal field from the fully nonlinear halo-matter cross correlation. Inside the one-halo regime, the average alignment of galaxies with density tracers no longer follows the tidal alignment prediction, likely reflecting nonlinear processes that must be considered when modeling IA on these scales. Finally, we discuss tidal alignment in the context of cosmic shear measurements.

  4. Alignability of Optical Interconnects

    NASA Astrophysics Data System (ADS)

    Beech, Russell Scott

    With the continuing drive towards higher speed, density, and functionality in electronics, electrical interconnects become inadequate. Due to optics' high speed and bandwidth, freedom from capacitive loading effects, and freedom from crosstalk, optical interconnects can meet more stringent interconnect requirements. But, an optical interconnect requires additional components, such as an optical source and detector, lenses, holographic elements, etc. Fabrication and assembly of an optical interconnect requires precise alignment of these components. The successful development and deployment of optical interconnects depend on how easily the interconnect components can be aligned and/or how tolerant the interconnect is to misalignments. In this thesis, a method of quantitatively specifying the relative difficulty of properly aligning an optical interconnect is described. Ways of using this theory of alignment to obtain design and packaging guidelines for optical interconnects are examined. The measure of the ease with which an optical interconnect can be aligned, called the alignability, uses the efficiency of power transfer as a measure of alignment quality. The alignability is related to interconnect package design through the overall cost measure, which depends upon various physical parameters of the interconnect, such as the cost of the components and the time required for fabrication and alignment. Through a mutual dependence on detector size, the relationship between an interconnect's alignability and its bandwidth, signal-to-noise ratio, and bit-error -rate is examined. The results indicate that a range of device sizes exists for which given performance threshold values are satisfied. Next, the alignability of integrated planar-optic backplanes is analyzed in detail. The resulting data show that the alignability can be optimized by varying the substrate thickness or the angle of reflection. By including the effects of crosstalk, in a multi-channel backplane, the

  5. Multiple nodes transfer alignment for airborne missiles based on inertial sensor network

    NASA Astrophysics Data System (ADS)

    Si, Fan; Zhao, Yan

    2017-09-01

    Transfer alignment is an important initialization method for airborne missiles because the alignment accuracy largely determines the performance of the missile. However, traditional alignment methods are limited by complicated and unknown flexure angle, and cannot meet the actual requirement when wing flexure deformation occurs. To address this problem, we propose a new method that uses the relative navigation parameters between the weapons and fighter to achieve transfer alignment. First, in the relative inertial navigation algorithm, the relative attitudes and positions are constantly computed in wing flexure deformation situations. Secondly, the alignment results of each weapon are processed using a data fusion algorithm to improve the overall performance. Finally, the feasibility and performance of the proposed method were evaluated under two typical types of deformation, and the simulation results demonstrated that the new transfer alignment method is practical and has high-precision.

  6. From conjugate volcanic rifted margins to micro-continent formation: Double breakup development of the Norwegian-Greenland Sea

    NASA Astrophysics Data System (ADS)

    Gernigon, Laurent; Blischke, Anett; Nasuti, Aziz; Olesen, Odleiv; Sand, Morten; Sveinn Arnarson, Thorarinn

    2014-05-01

    lithospheric deformation with the precedent thinning system. Diking and disconnected lithospheric plumbing are proposed to explain the Eocene breakup. After the first phase of continental breakup, two major phases of spreading influenced the Norwegian-Greenland Sea. Phase I (from C24 to C21r, ~54 to 49 Ma) marks the earliest phase of spreading, probably initiated in the central and outer part of the Møre Basin. During this period, the formation of overlapping systems and pseudo-fault development, indirectly influenced by the proto-margin segmentation, suggests the presence of additional micro-plates in the Norwegian-Greenland Sea. We also observed a significant change in the oceanic spreading system in the late Early Eocene. Based on observations from the surrounding areas, this supports a major and distinct tectonic and magmatic event in the Norwegian-Greenland Sea at around C21r (49-47.9 Ma), the beginning of a second phase. During Phase II, from C21r-C12 or possibly younger (48-<32 Ma) of the Norway Basin development, spreading rates decreased, spreading direction changed leading to the formation of unexpected N-S oriented oceanic fracture zones. Phase II probably coincides with the climax of extension and possibly local spreading that is suspected in the southern part of the Jan Mayen micro-continent forming a complex area of oceanic, transitional and continental fragments before its complete dislocation from East Greenland in Latest Oligocene.

  7. Solar Wind-Magnetosphere Coupling Influences on Pseudo-Breakup Activity

    NASA Technical Reports Server (NTRS)

    Fillingim, M. O.; Brittnacher, M.; Parks, G. K.; Germany, G. A.; Spann, J. F.

    1998-01-01

    Pseudo-breakups are brief, localized aurora[ arc brightening, which do not lead to a global expansion, are historically observed during the growth phase of substorms. Previous studies have demonstrated that phenomenologically there is very little difference between substorm onsets and pseudo-breakups except for the degree of localization and the absence of a global expansion phase. A key open question is what physical mechanism prevents a pseudo-breakup form expanding globally. Using Polar Ultraviolet Imager (UVI) images, we identify periods of pseudo-breakup activity. Foe the data analyzed we find that most pseudo-breakups occur near local midnight, between magnetic local times of 21 and 03, at magnetic latitudes near 70 degrees, through this value may change by several degrees. While often discussed in the context of substorm growth phase events, pseudo-breakups are also shown to occur during prolonged relatively inactive periods. These quiet time pseudo-breakups can occur over a period of several hours without the development of a significant substorm for at least an hour after pseudo-breakup activity stops. In an attempt to understand the cause of quiet time pseudo-breakups, we compute the epsilon parameter as a measure of the efficiency of solar wind-magnetosphere coupling. It is noted that quiet time pseudo-breakups occur typically when epsilon is low; less than about 50 GW. We suggest that quiet time pseudo-breakups are driven by relatively small amounts of energy transferred to the magnetosphere by the solar wind insufficient to initiate a substorm expansion onset.

  8. Temporal variations in river-ice break-up over the Mackenzie River Basin, Canada

    NASA Astrophysics Data System (ADS)

    de Rham, Laurent P.; Prowse, Terry D.; Bonsal, Barrie R.

    2008-02-01

    SummaryFor northern and arctic regions, the spring break-up period has important socio-economic, ecological and morphological effects. While these impacts are reasonably well understood, spatial and temporal assessments of break-up timing and duration remain limited due to the lack of readily available hydrometric data. For this study, the Mackenzie River Basin (MRB) of Canada is selected as a test watershed in which the spatial and temporal aspects of observed (1913-2002) spring river-ice break-up are characterized. Data from 29 Water Survey of Canada gauging sites are used including the commonly assessed 'Last B date' (last ice effect) and two hydrometric variables extracted directly from original water-level recording charts (the timing of initiation of break-up and peak water-level during break-up). It is found that the extracted variables provide a more physically based quantitative description of the break-up season in the MRB compared to the 'Last B date' method. On average, the northwards progressing ice break-up season within the MRB lasts ∼8 weeks but historically has varied within a window representative of ∼3 months of the year. The break-up period at specific locations varies from 4 days to 4 weeks. Results also indicate an anomalous zone of earlier spring break-up in the upper Peace and Athabasca region that may be partially related to the effects of flow regulation. In addition, the Mann-Kendall test reveals significantly earlier trends in the timing of spring break-up (∼1 day/decade) in upstream portions of the major tributaries of the MRB over the period 1970-2002. While similar trends have been found for other hydroclimatic variables in the basin, this study highlights the temporal patterns and variability of the spring break-up period in the Mackenzie River system.

  9. Heterogeneous Data Fusion via Space Alignment Using Nonmetric Multidimensional Scaling

    SciTech Connect

    Choo, Jaegul; Bohn, Shawn J.; Nakamura, Grant C.; White, Amanda M.; Park, Haesun

    2012-04-26

    Heterogeneous data sets are typically represented in different feature spaces, making it difficult to analyze relationships spanning different data sets even when they are semantically related. Data fusion via space alignment can remedy this task by integrating multiple data sets lying in different spaces into one common space. Given a set of reference correspondence data that share the same semantic meaning across different spaces, space alignment attempts to place the corresponding reference data as close together as possible, and accordingly, the entire data are aligned in a common space. Space alignment involves optimizing two potentially conflicting criteria: minimum deformation of the original relationships and maximum alignment between the different spaces. To solve this problem, we provide a novel graph embedding framework for space alignment, which converts each data set into a graph and assigns zero distance between reference correspondence pairs resulting in a single graph. We propose a graph embedding method for fusion based on nonmetric multidimensional scaling (MDS). Its criteria using the rank order rather than the distance allows nonmetric MDS to effectively handle both deformation and alignment. Experiments using parallel data sets demonstrate that our approach works well in comparison to existing methods such as constrained Laplacian eigenmaps, Procrustes analysis, and tensor decomposition. We also present standard cross-domain information retrieval tests as well as interesting visualization examples using space alignment.

  10. Correlations between polarization observables in inclusive deuteron breakup

    SciTech Connect

    Kuehn, B.; Perdrisat, C.F.; Strokovsky, E.A.

    1995-10-01

    The tensor analyzing power T{sub 20} and the spin transfer coefficient {kappa}{sub 0} for the deuteron breakup reaction {sup 1}H(d, p)X at 0{degrees} and at high energy are functions of the D/S ratio of the deuteron wave function (DWF) and are related by the equation of a circle in the {kappa}{sub 0}-T{sub 20} plane if (1) the deuteron wave function has the commonly accepted S- and D-component structures and (2) the mechanism of the breakup reaction does not change the spin of the detected proton. This correlation of the two polarization observables is independent of any model of the deuteron wave function with 2-component structure. The experimental data deviate from the {kappa}{sub 0}-T{sub 20} circle, indicating that at least one of the above assumptions is not fulfilled. Two assumptions are discussed to explain this deviation: (1) the DWF has additional components, for example the N{sup *}N P-wave and (2) complicated spin-dependent interfering graphs change the spin of the detected proton. We suggest an experimental way to verify the first of these assumptions by searching for the {eta} decay of the negative parity N{sup *}(1535) baryon of the N{sup *}N component in the deuteron ground state. 17 refs., 3 figs.

  11. Numerical Simulation of Thin Film Breakup on Nonwettable Surfaces

    NASA Astrophysics Data System (ADS)

    Suzzi, N.; Croce, G.

    2017-01-01

    When a continuous film flows on a nonwettable substrate surface, it may break up, with the consequent formation of a dry-patch. The actual shape of the resulting water layer is of great interest in several engineering applications, from in-flight icing simulation to finned dehumidifier behavior modeling. Here, a 2D numerical solver for the prediction of film flow behavior is presented. The effect of the contact line is introduced via the disjoining pressure terms, and both gravity and shear are included in the formulation. The code is validated with literature experimental data for the case of a stationary dry-patch on an inclined plane. Detailed numerical results are compared with literature simplified model prediction. Numerical simulation are then performed in order to predict the threshold value of the film thickness allowing for film breakup and to analyze the dependence of the dynamic contact angle on film velocity and position along the contact line. Those informations will be useful in order to efficiently predict more complex configuration involving multiple breakups on arbitrarily curved substrate surfaces (as those involved in in-flight icing phenomena on aircraft).

  12. Distribution of living Cupressaceae reflects the breakup of Pangea

    PubMed Central

    Mao, Kangshan; Milne, Richard I.; Zhang, Libing; Peng, Yanling; Liu, Jianquan; Thomas, Philip; Mill, Robert R.; S. Renner, Susanne

    2012-01-01

    Most extant genus-level radiations in gymnosperms are of Oligocene age or younger, reflecting widespread extinction during climate cooling at the Oligocene/Miocene boundary [∼23 million years ago (Ma)]. Recent biogeographic studies have revealed many instances of long-distance dispersal in gymnosperms as well as in angiosperms. Acting together, extinction and long-distance dispersal are likely to erase historical biogeographic signals. Notwithstanding this problem, we show that phylogenetic relationships in the gymnosperm family Cupressaceae (162 species, 32 genera) exhibit patterns expected from the Jurassic/Cretaceous breakup of Pangea. A phylogeny was generated for 122 representatives covering all genera, using up to 10,000 nucleotides of plastid, mitochondrial, and nuclear sequence per species. Relying on 16 fossil calibration points and three molecular dating methods, we show that Cupressaceae originated during the Triassic, when Pangea was intact. Vicariance between the two subfamilies, the Laurasian Cupressoideae and the Gondwanan Callitroideae, occurred around 153 Ma (124–183 Ma), when Gondwana and Laurasia were separating. Three further intercontinental disjunctions involving the Northern and Southern Hemisphere are coincidental with or immediately followed the breakup of Pangea. PMID:22550176

  13. Plethora of transitions during breakup of liquid filaments

    PubMed Central

    Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Thete, Sumeet Suresh; Sambath, Krishnaraj; Hutchings, Ian M.; Hinch, John; Lister, John R.; Basaran, Osman A.

    2015-01-01

    Thinning and breakup of liquid filaments are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the filament radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the governing equations become singular and the filament breaks. In slightly viscous liquids, thinning initially occurs in an inertial regime where inertial and capillary forces balance. By contrast, in highly viscous liquids, initial thinning occurs in a viscous regime where viscous and capillary forces balance. As the filament thins, viscous forces in the former case and inertial forces in the latter become important, and theory shows that the filament approaches breakup in the final inertial–viscous regime where all three forces balance. However, previous simulations and experiments reveal that transition from an initial to the final regime either occurs at a value of filament radius well below that predicted by theory or is not observed. Here, we perform new simulations and experiments, and show that a thinning filament unexpectedly passes through a number of intermediate transient regimes, thereby delaying onset of the inertial–viscous regime. The new findings have practical implications regarding formation of undesirable satellite droplets and also raise the question as to whether similar dynamical transitions arise in other free-surface flows such as coalescence that also exhibit singularities. PMID:25825761

  14. Scaling During Drop Formation and Filament (Thread) Breakup

    NASA Astrophysics Data System (ADS)

    Wagoner, Brayden; Thete, Sumeet; Basaran, Osman

    2016-11-01

    Many free surface flows such as drop formation, filament (thread) breakup, and drop coalescence are important in applications as diverse as ink jet printing, atomization, and emulsion science and technology. A common feature of these flows is that they all exhibit finite time singularities. When a liquid filament undergoes capillary thinning and tends toward pinch-off, it is instructive to monitor how certain quantities, such as the thread's radius, vary with time remaining until the pinch-off singularity. Experimental determination of this so-called scaling behavior of thread radius and other quantities is important for testing scaling theories and the accuracy of numerical simulations of free surface flows. Conversely, the experimental measurements can be used to develop new theories when none are available. In this talk, we will present some novel ways of experimentally measuring scaling behaviors. The results will be highlighted in terms of experiments involving the formation and breakup of drops and filaments of (a) simple or pure Newtonian fluids and also (b) particle-laden liquids or suspensions containing non-Brownian particles.

  15. Break-up of New Orleans Households after Hurricane Katrina

    PubMed Central

    Rendall, Michael S.

    2011-01-01

    Theory and evidence on disaster-induced population displacement have focused on individual and population-subgroup characteristics. Less is known about impacts on households. I estimate excess incidence of household break-up due to Hurricane Katrina by comparing a probability sample of pre-Katrina New Orleans resident adult household heads and non–household heads (N = 242), traced just over a year later, with a matched sample from a nationally representative survey over an equivalent period. One in three among all adult non–household heads, and one in two among adult children of household heads, had separated from the household head 1 year post-Katrina. These rates were, respectively, 2.2 and 2.7 times higher than national rates. A 50% higher prevalence of adult children living with parents in pre-Katrina New Orleans than nationally increased the hurricane’s impact on household break-up. Attention to living arrangements as a dimension of social vulnerability in disaster recovery is suggested. PMID:21709733

  16. Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

    NASA Astrophysics Data System (ADS)

    Kaercher, P. M.; Zepeda-Alarcon, E.; Prakapenka, V.; Kanitpanyacharoen, W.; Smith, J.; Sinogeikin, S. V.; Wenk, H. R.

    2014-12-01

    The crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, yet little is known about its deformation mechanisms. Information about how stishovite deforms under stress is important for understanding subduction of quartz-bearing crustal rocks into the mantle. Particularly, stishovite is elastically anisotropic and thus development of crystallographic preferred orientation (CPO) during deformation may contribute to seismic anomalies in the mantle. We converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. Diffraction patterns were collected in situ in radial geometry at the Advanced Light Source (ALS) and the Advanced Photon Source (APS) to examine development of CPO during deformation. We find that (001) poles preferentially align with the compression direction and infer deformation mechanisms leading to the observed CPO with visco-plastic self consistent (VPSC) polycrystal plasticity models. Our results show pyramidal and basal slip are most likely active at high pressure and ambient temperature, in agreement with transmission electron microscopy (TEM) studies of rutile (TiO2) and paratellurite (TeO2), which are isostructural to stishovite. Conversely other TEM studies of stishovite done at higher temperature suggest dominant prismatic slip. This indicates that a variety of slip systems may be active in stishovite, depending on conditions. As a result, stishovite's contribution to the seismic signature in the mantle may vary as a function of pressure and temperature and thus depth.

  17. Crustal deformation

    NASA Astrophysics Data System (ADS)

    Larson, Kristine M.

    1995-07-01

    Geodetic measurements of crustal deformation provide direct tests of geophysical models which are used to describe the dynamics of the Earth. Although geodetic observations have been made throughout history, only in the last several hundred years have they been sufficiently precise for geophysical studies. In the 19th century, these techniques included leveling and triangulation. Approximately 25 years ago, trilateration measurements were initiated by the USGS (United States Geological Survey) to monitor active faults in the United States. Several years later, NASA (National Aeronautics and Space Administration) begin an effort to measure plate tectonic motions on a global scale, using space geodetic techniques, VLBI (Very Long Baseline Interferometry) and SLR (Satellite Laser Ranging). The period covered by this report to the IUGG, 1991-1994, was a transition period in the field of crustal deformation. Trilateration measurements (previously the backbone of measurements across plate boundaries in the western United States and Alaska) have been abandoned. This system was labor-intensive, involved highly trained crews to carry out the observations, and only measured the length between sites. In addition, NASA drastically cut the budgets for VLBI and SLR during this period. Fixed site VLBI systems are still operational, but mobile VLBI measurements in North America have ceased. SLR measurements continue on a global scale, but the remaining crustal deformation measurements are now being made with the Global Positioning System (GPS). Nonetheless, because of the time scales involved, older geodetic data (including leveling, triangulation, and trilateration) continue to be important for many geophysical studies.

  18. New tectonic data constrain the mechanisms of breakup along the Gulf of California

    NASA Astrophysics Data System (ADS)

    Bot, Anna; Geoffroy, Laurent; Authemayou, Christine; Graindorge, David

    2014-05-01

    The Gulf of California is resulting from an oblique-rift system due to the separation of the Pacific and the North American plates in the ~N110E to ~N125E trend. The age, nature and orientation of strain which ended with continental break-up and incipient oceanization at ~3.6 Ma, is largely misunderstood. It is generally proposed that early stages of extension began at around 12 Ma with strain partitioning into two components: a pure ENE directed extension in the Gulf Extensional Province (which includes Sonora and the eastern Baja California Peninsula in Mexico) and a dextral strike-slip displacement west of the Baja California Peninsula along the San Benito and Tosco-Abreojos faults. This evolution would have lasted ~5-6 Ma when a new transtensional strain regime took place. This regime, with extension trending ~N110E +/-10° , led to the final break-up and the subsequent individualization of a transform-fault system and subordoned short oceanic ridges. This two-steps interpretation has recently been challenged by authors suggesting a continuous transtensional extension from 12Ma in the trend of the PAC-NAM plates Kinematic. We question both of those models in term of timing and mode of accommodation basing ourselves on field investigations in Baja California Sur (Mexico). The volcano-sedimentary formations of the Comondù group dated 25 to 20 Ma exhibit clear examples of syn-sedimentary and syn-magmatic extensive deformations. This extension, oriented N65° E+/-15° , is proposed to initiate during the Magdalena Plate subduction. It would be related to the GOC initialization. In addition to this finding, we present tectonic and dating evidences of complex detachment-faulting tectonics varying in trend and kinematics with time and space for the development to the south of Baja California Sur. The extension associated with the early detachment-fault system trended ~N110E. From ~17 Ma to, probably, ~7-8 Ma, this extension controlled the early development of the San

  19. Features of Capillary Breakup of a Liquid Jet at Ohnesorge Numbers Larger Than Unity

    NASA Astrophysics Data System (ADS)

    Safronov, A. A.

    2017-01-01

    A theoretical study has been made of the forced capillary breakup of a jet of viscous liquid at a value of the Ohnesorge number larger than unity. The regions of breakup of the jet without the formation of satellites have been determined. The dependences of the dimensions of main and satellite droplets on the wave number have been obtained for different Ohnesorge numbers.

  20. Non-rigid alignment in electron tomography in materials science.

    PubMed

    Printemps, Tony; Bernier, Nicolas; Bleuet, Pierre; Mula, Guido; Hervé, Lionel

    2016-09-01

    Electron tomography is a key technique that enables the visualization of an object in three dimensions with a resolution of about a nanometre. High-quality 3D reconstruction is possible thanks to the latest compressed sensing algorithms and/or better alignment and preprocessing of the 2D projections. Rigid alignment of 2D projections is routine in electron tomography. However, it cannot correct misalignments induced by (i) deformations of the sample due to radiation damage or (ii) drifting of the sample during the acquisition of an image in scanning transmission electron microscope mode. In both cases, those misalignments can give rise to artefacts in the reconstruction. We propose a simple-to-implement non-rigid alignment technique to correct those artefacts. This technique is particularly suited for needle-shaped samples in materials science. It is initiated by a rigid alignment of the projections and it is then followed by several rigid alignments of different parts of the projections. Piecewise linear deformations are applied to each projection to force them to simultaneously satisfy the rigid alignments of the different parts. The efficiency of this technique is demonstrated on three samples, an intermetallic sample with deformation misalignments due to a high electron dose typical to spectroscopic electron tomography, a porous silicon sample with an extremely thin end particularly sensitive to electron beam and another porous silicon sample that was drifting during image acquisitions.

  1. Near Term Effects from Satellite Break-Ups on Manned Space Activities

    NASA Technical Reports Server (NTRS)

    Theall, J. R.; Matney, M. J.

    2000-01-01

    Since 1961, almost 160 satellite break-ups have occurred on-orbit, and have been the major contributor to the growth of the orbital debris population. When a satellite breaks up, the debris exists in a relatively concentrated form, orbiting in a loose cloud with the parent body until orbital perturbations disperse the cloud into the average background. Manned space activities, which usually take place in low Earth orbit at altitudes less than 500 km, have been continuous for the past I I years while Mir was inhabited and promise to be again continuous when the International Space Station becomes permanently manned. This paper surveys historical breakups over the last I I years to determine the number that affect altitudes lower than 500 km. Selected breakup are analyzed using NASA's Satellite Breakup Risk Assessment Model (SBRAM) to determine the specific short term risk from those breakups to manned missions.

  2. Near Term Effects from Satellite Break-Ups on Manned Space Activities

    NASA Technical Reports Server (NTRS)

    Theall, J. R.; Matney, M. J.

    2000-01-01

    Since 1961, almost 160 satellite break-ups have occurred on-orbit, and have been the major contributor to the growth of the orbital debris population. When a satellite breaks up, the debris exists in a relatively concentrated form, orbiting in a loose cloud with the parent body until orbital perturbations disperse the cloud into the average background. Manned space activities, which usually take place in low Earth orbit at altitudes less than 500 km, have been continuous for the past I I years while Mir was inhabited and promise to be again continuous when the International Space Station becomes permanently manned. This paper surveys historical breakups over the last I I years to determine the number that affect altitudes lower than 500 km. Selected breakup are analyzed using NASA's Satellite Breakup Risk Assessment Model (SBRAM) to determine the specific short term risk from those breakups to manned missions.

  3. Quantifying torso deformity in scoliosis

    NASA Astrophysics Data System (ADS)

    Ajemba, Peter O.; Kumar, Anish; Durdle, Nelson G.; Raso, V. James

    2006-03-01

    Scoliosis affects the alignment of the spine and the shape of the torso. Most scoliosis patients and their families are more concerned about the effect of scoliosis on the torso than its effect on the spine. There is a need to develop robust techniques for quantifying torso deformity based on full torso scans. In this paper, deformation indices obtained from orthogonal maps of full torso scans are used to quantify torso deformity in scoliosis. 'Orthogonal maps' are obtained by applying orthogonal transforms to 3D surface maps. (An 'orthogonal transform' maps a cylindrical coordinate system to a Cartesian coordinate system.) The technique was tested on 361 deformed computer models of the human torso and on 22 scans of volunteers (8 normal and 14 scoliosis). Deformation indices from the orthogonal maps correctly classified up to 95% of the volunteers with a specificity of 1.00 and a sensitivity of 0.91. In addition to classifying scoliosis, the system gives a visual representation of the entire torso in one view and is viable for use in a clinical environment for managing scoliosis.

  4. New Insights Into the Farallon Plate Break-Up

    NASA Astrophysics Data System (ADS)

    Barckhausen, U.; Engels, M.; Cande, S.; Ranero, C. R.; Weinrebe, W.

    2005-12-01

    The break-up of the Farallon plate was the most important event during the Early Miocene plate tectonic reorganization of the East Pacific. The opening of a new oceanic spreading center perpendicular to the existing Pacific spreading is unique and probably had far-reaching consequences for the active continental margins of Central- and South America. Most of the original fissure where the Farallon plate split into the Cocos plate and the Nazca plate has already been subducted beneath Central- and South America together with much of the oceanic crust that was formed during the early phase of Cocos-Nazca spreading. This made a full reconstruction of plate kinematics in the area back to the time of the opening poorly constrained and left many questions open about the mechanisms involved and the subduction zones affected by this event. During a R/V Sonne cruise in late 2004 the area conjugate to the Farallon remains offshore Costa Rica and Ecuador was investigated in the Central Pacific around 120° W, just south of the Equator. With the new magnetic data it was possible to identify seafloor spreading anomalies between chrons 7 and 5A for a large area in the Central Pacific. In combination with picks of the same anomalies from the Cocos- and Nazca plates it was possible to trace back the history of the Farallon break-up in a three-plate reconstruction. The plate motion of the Pacific plate in the hotspot reference frame provides the absolute position of the initial triple junction and the strike direction of the newly formed Cocos-Nazca spreading center, revealing its close relation to the Galapagos hotspot and the Central American subduction zone. The multibeam bathymetry data from the research area highlight the details of an increased magmatic activity near the newly formed triple junction and the reorganization of the seafloor spreading that followed the break-up and which finally resulted in a major ridge jump at the East Pacific Rise during chron 6.

  5. Breakup and early seafloor spreading between India and Antarctica

    NASA Astrophysics Data System (ADS)

    Gaina, Carmen; Müller, R. Dietmar; Brown, Belinda; Ishihara, Takemi; Ivanov, Sergey

    2007-07-01

    We present a tectonic interpretation of the breakup and early seafloor spreading between India and Antarctica based on improved coverage of potential field and seismic data off the east Antarctic margin between the Gunnerus Ridge and the Bruce Rise. We have identified a series of ENE trending Mesozoic magnetic anomalies from chron M9o (~130.2 Ma) to M2o (~124.1 Ma) in the Enderby Basin, and M9o to M4o (~126.7 Ma) in the Princess Elizabeth Trough and Davis Sea Basin, indicating that India-Antarctica and India-Australia breakups were roughly contemporaneous. We present evidence for an abandoned spreading centre south of the Elan Bank microcontinent; the estimated timing of its extinction corresponds to the early surface expression of the Kerguelen Plume at the Southern Kerguelen Plateau around 120 Ma. We observe an increase in spreading rate from west to east, between chron M9 and M4 (38-54 mm yr-1), along the Antarctic margin and suggest the tectono-magmatic segmentation of oceanic crust has been influenced by inherited crustal structure, the kinematics of Gondwanaland breakup and the proximity to the Kerguelen hotspot. A high-amplitude, E-W oriented magnetic lineation named the Mac Robertson Coast Anomaly (MCA), coinciding with a landwards step-down in basement observed in seismic reflection data, is tentatively interpreted as the boundary between continental/transitional zone and oceanic crust. The exposure of lower crustal rocks along the coast suggests that this margin formed in a metamorphic core complex extension mode with a high strength ratio between upper and lower crust, which typically occurs above anomalously hot mantle. Together with the existence of the MCA zone this observation suggests that a mantle temperature anomaly predated the early surface outpouring/steady state magmatic production of the Kerguelen LIP. An alternative model suggests that the northward ridge jump was limited to the Elan Bank region, whereas seafloor spreading continued in the

  6. The tree alignment problem.

    PubMed

    Varón, Andrés; Wheeler, Ward C

    2012-11-09

    The inference of homologies among DNA sequences, that is, positions in multiple genomes that share a common evolutionary origin, is a crucial, yet difficult task facing biologists. Its computational counterpart is known as the multiple sequence alignment problem. There are various criteria and methods available to perform multiple sequence alignments, and among these, the minimization of the overall cost of the alignment on a phylogenetic tree is known in combinatorial optimization as the Tree Alignment Problem. This problem typically occurs as a subproblem of the Generalized Tree Alignment Problem, which looks for the tree with the lowest alignment cost among all possible trees. This is equivalent to the Maximum Parsimony problem when the input sequences are not aligned, that is, when phylogeny and alignments are simultaneously inferred. For large data sets, a popular heuristic is Direct Optimization (DO). DO provides a good tradeoff between speed, scalability, and competitive scores, and is implemented in the computer program POY. All other (competitive) algorithms have greater time complexities compared to DO. Here, we introduce and present experiments a new algorithm Affine-DO to accommodate the indel (alignment gap) models commonly used in phylogenetic analysis of molecular sequence data. Affine-DO has the same time complexity as DO, but is correctly suited for the affine gap edit distance. We demonstrate its performance with more than 330,000 experimental tests. These experiments show that the solutions of Affine-DO are close to the lower bound inferred from a linear programming solution. Moreover, iterating over a solution produced using Affine-DO shows little improvement. Our results show that Affine-DO is likely producing near-optimal solutions, with approximations within 10% for sequences with small divergence, and within 30% for random sequences, for which Affine-DO produced the worst solutions. The Affine-DO algorithm has the necessary scalability and

  7. The tree alignment problem

    PubMed Central

    2012-01-01

    Background The inference of homologies among DNA sequences, that is, positions in multiple genomes that share a common evolutionary origin, is a crucial, yet difficult task facing biologists. Its computational counterpart is known as the multiple sequence alignment problem. There are various criteria and methods available to perform multiple sequence alignments, and among these, the minimization of the overall cost of the alignment on a phylogenetic tree is known in combinatorial optimization as the Tree Alignment Problem. This problem typically occurs as a subproblem of the Generalized Tree Alignment Problem, which looks for the tree with the lowest alignment cost among all possible trees. This is equivalent to the Maximum Parsimony problem when the input sequences are not aligned, that is, when phylogeny and alignments are simultaneously inferred. Results For large data sets, a popular heuristic is Direct Optimization (DO). DO provides a good tradeoff between speed, scalability, and competitive scores, and is implemented in the computer program POY. All other (competitive) algorithms have greater time complexities compared to DO. Here, we introduce and present experiments a new algorithm Affine-DO to accommodate the indel (alignment gap) models commonly used in phylogenetic analysis of molecular sequence data. Affine-DO has the same time complexity as DO, but is correctly suited for the affine gap edit distance. We demonstrate its performance with more than 330,000 experimental tests. These experiments show that the solutions of Affine-DO are close to the lower bound inferred from a linear programming solution. Moreover, iterating over a solution produced using Affine-DO shows little improvement. Conclusions Our results show that Affine-DO is likely producing near-optimal solutions, with approximations within 10% for sequences with small divergence, and within 30% for random sequences, for which Affine-DO produced the worst solutions. The Affine-DO algorithm has

  8. Precision alignment device

    DOEpatents

    Jones, N.E.

    1988-03-10

    Apparatus for providing automatic alignment of beam devices having an associated structure for directing, collimating, focusing, reflecting, or otherwise modifying the main beam. A reference laser is attached to the structure enclosing the main beam producing apparatus and produces a reference beam substantially parallel to the main beam. Detector modules containing optical switching devices and optical detectors are positioned in the path of the reference beam and are effective to produce an electrical output indicative of the alignment of the main beam. This electrical output drives servomotor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam. 5 figs.

  9. Precision alignment device

    DOEpatents

    Jones, Nelson E.

    1990-01-01

    Apparatus for providing automatic alignment of beam devices having an associated structure for directing, collimating, focusing, reflecting, or otherwise modifying the main beam. A reference laser is attached to the structure enclosing the main beam producing apparatus and produces a reference beam substantially parallel to the main beam. Detector modules containing optical switching devices and optical detectors are positioned in the path of the reference beam and are effective to produce an electrical output indicative of the alignment of the main beam. This electrical output drives servomotor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam.

  10. Hybrid vehicle motor alignment

    DOEpatents

    Levin, Michael Benjamin

    2001-07-03

    A rotor of an electric motor for a motor vehicle is aligned to an axis of rotation for a crankshaft of an internal combustion engine having an internal combustion engine and an electric motor. A locator is provided on the crankshaft, a piloting tool is located radially by the first locator to the crankshaft. A stator of the electric motor is aligned to a second locator provided on the piloting tool. The stator is secured to the engine block. The rotor is aligned to the crankshaft and secured thereto.

  11. Breakup of a homeobox cluster after genome duplication in teleosts

    PubMed Central

    Mulley, John F.; Chiu, Chi-hua; Holland, Peter W. H.

    2006-01-01

    Several families of homeobox genes are arranged in genomic clusters in metazoan genomes, including the Hox, ParaHox, NK, Rhox, and Iroquois gene clusters. The selective pressures responsible for maintenance of these gene clusters are poorly understood. The ParaHox gene cluster is evolutionarily conserved between amphioxus and human but is fragmented in teleost fishes. We show that two basal ray-finned fish, Polypterus and Amia, each possess an intact ParaHox cluster; this implies that the selective pressure maintaining clustering was lost after whole-genome duplication in teleosts. Cluster breakup is because of gene loss, not transposition or inversion, and the total number of ParaHox genes is the same in teleosts, human, mouse, and frog. We propose that this homeobox gene cluster is held together in chordates by the existence of interdigitated control regions that could be separated after locus duplication in the teleost fish. PMID:16801555

  12. Inadvertent Earth Reentry Breakup Analysis for the New Horizons Mission

    NASA Technical Reports Server (NTRS)

    Ling, Lisa M.; Salama, Ahmed; Ivanov, Mark; McRonald, Angus

    2007-01-01

    The New Horizons (NH) spacecraft was launched in January 2006 aboard an Atlas V launch vehicle, in a mission to explore Pluto, its moons, and other bodies in the Kuiper Belt. The NH spacecraft is powered by a Radioisotope Thermoelectric Generator (RTG) which encases multiple General Purpose Heat Source (GPHS) modules. Thus, a pre-launch vehicle breakup analysis for an inadvertent atmospheric reentry in the event of a launch failure was required to assess aerospace nuclear safety and for launch contingency planning. This paper addresses potential accidental Earth reentries analyzed at the Jet Propulsion Laboratory (JPL) which may arise during the ascent to parking orbit, resulting in a suborbital reentry, as well as a departure from parking orbit, resulting in an orbital reentry.

  13. Droplet breakup in accelerating gas flows. Part 2: Secondary atomization

    NASA Technical Reports Server (NTRS)

    Zajac, L. J.

    1973-01-01

    An experimental investigation to determine the effects of an accelerating gas flow on the atomization characteristics of liquid sprays was conducted. The sprays were produced by impinging two liquid jets. The liquid was molten wax and the gas was nitrogen. The use of molten wax allowed for a quantitative measure of the resulting dropsize distribution. The results of this study, indicate that a significant amount of droplet breakup will occur as a result of the action of the gas on the liquid droplets. Empirical correlations are presented in terms of parameters that were found to affect the mass median dropsize most significantly, the orifice diameter, the liquid injection velocity, and the maximum gas velocity. An empirical correlation for the normalized dropsize distribution is also presented. These correlations are in a form that may be incorporated readily into existing combustion model computer codes for the purpose of calculating rocket engine combustion performance.

  14. The role of surfactants in drop formation and thread breakup

    NASA Astrophysics Data System (ADS)

    Kamat, Pritish; Wagoner, Brayden; Thete, Sumeet; Basaran, Osman

    2016-11-01

    The ability of surfactants to adsorb onto and lower the surface tension of water-air and water-oil interfaces is exploited in industrial applications, nature, and everyday life. An important example is provided by drop formation where a thinning liquid thread connects an about-to-form globular, primary drop to the rest of the liquid that remains on the nozzle when the primary drop falls from it. Surfactants can affect pinch-off in two ways: first, by lowering surface tension they lower capillary pressure (which equals, to highest order, surface tension divided by thread radius), and second, as surfactant concentration along the interface can be non-uniform, they cause the interface to be subjected to a gradient of surface tension, or Marangoni stress. By means of high-accuracy simulations and supporting experiments, we clarify the role played by surfactants on drop formation and thread breakup.

  15. Space debris characterization in support of a satellite breakup model

    NASA Technical Reports Server (NTRS)

    Fortson, Bryan H.; Winter, James E.; Allahdadi, Firooz A.

    1992-01-01

    The Space Kinetic Impact and Debris Branch began an ambitious program to construct a fully analytical model of the breakup of a satellite under hypervelocity impact. In order to provide empirical data with which to substantiate the model, debris from hypervelocity experiments conducted in a controlled laboratory environment were characterized to provide information of its mass, velocity, and ballistic coefficient distributions. Data on the debris were collected in one master data file, and a simple FORTRAN program allows users to describe the debris from any subset of these experiments that may be of interest to them. A statistical analysis was performed, allowing users to determine the precision of the velocity measurements for the data. Attempts are being made to include and correlate other laboratory data, as well as those data obtained from the explosion or collision of spacecraft in low earth orbit.

  16. Dynamical eikonal approximation in breakup reactions of {sup 11}Be

    SciTech Connect

    Goldstein, G.; Baye, D.

    2006-02-15

    The dynamical eikonal approximation is a quantal method unifying the semiclassical time-dependent and eikonal methods by taking into account interference effects. The principle of the calculation is described and expressions for different types of cross sections are established for two variants of the method, differing by a phase choice. The 'coherent' variant respects rotational symmetry around the beam axis and is therefore prefered. A good agreement is obtained with experimental differential and integrated cross sections for the elastic breakup of the {sup 11}Be halo nucleus on {sup 12}C and {sup 208}Pb near 70 MeV/nucleon, without any parameter adjustment. The dynamical approximation is compared with the traditional eikonal method. Differences are analyzed and the respective merits of both methods are discussed.

  17. Inversion Breakup in Small Rocky Mountain and Alpine Basins

    SciTech Connect

    Whiteman, Charles D.; Pospichal, Bernhard; Eisenbach, Stefan; Weihs, P.; Clements, Craig B.; Steinacker, Reinhold; Mursch-Radlgruber, Erich; Dorninger, Manfred

    2004-08-01

    Comparisons are made between the post-sunrise breakup of temperature inversions in two similar closed basins in quite different climate settings, one in the eastern Alps and one in the Rocky Mountains. The small, high-altitude, limestone sinkholes have both experienced extreme temperature minima below -50°C. On undisturbed clear nights, temperature inversions reach to 120 m heights in both sinkholes, but are much stronger in the drier Rocky Mountain basin (24K versus 13K). Inversion destruction takes place 2.6 to 3 hours after sunrise and is accomplished primarily by subsidence warming associated with the removal of air from the base of the inversion by the upslope flows that develop over the sidewalls. Differences in inversion strengths and post-sunrise heating rates are caused by differences in the surface energy budget, with drier soil and a higher sensible heat flux in the Rocky Mountain sinkhole.

  18. Beam breakup in an advanced linear induction accelerator

    DOE PAGES

    Ekdahl, Carl August; Coleman, Joshua Eugene; McCuistian, Brian Trent

    2016-07-01

    Two linear induction accelerators (LIAs) have been in operation for a number of years at the Los Alamos Dual Axis Radiographic Hydrodynamic Test (DARHT) facility. A new multipulse LIA is being developed. We have computationally investigated the beam breakup (BBU) instability in this advanced LIA. In particular, we have explored the consequences of the choice of beam injector energy and the grouping of LIA cells. We find that within the limited range of options presently under consideration for the LIA architecture, there is little adverse effect on the BBU growth. The computational tool that we used for this investigation wasmore » the beam dynamics code linear accelerator model for DARHT (LAMDA). In conclusion, to confirm that LAMDA was appropriate for this task, we first validated it through comparisons with the experimental BBU data acquired on the DARHT accelerators.« less

  19. Helium breakup states in 10Be and 12Be

    NASA Astrophysics Data System (ADS)

    Freer, M.; Angélique, J. C.; Axelsson, L.; Benoit, B.; Bergmann, U.; Catford, W. N.; Chappell, S. P.; Clarke, N. M.; Curtis, N.; D'arrigo, A.; de Góes Brennard, E.; Dorvaux, O.; Fulton, B. R.; Giardina, G.; Gregori, C.; Grévy, S.; Hanappe, F.; Kelly, G.; Labiche, M.; Le Brun, C.; Leenhardt, S.; Lewitowicz, M.; Markenroth, K.; Marqués, F. M.; Murgatroyd, J. T.; Nilsson, T.; Ninane, A.; Orr, N. A.; Piqueras, I.; Saint Laurent, M. G.; Singer, S. M.; Sorlin, O.; Stuttgé, L.; Watson, D. L.

    2001-03-01

    The breakup of 10,12Be into He clusters has been studied using the p,12C(12Be,6He,6He) and 12C(12Be,4He,6He) inelastic scattering and two neutron transfer reactions with a 378 MeV 12Be beam incident on 12C and (CH2)n targets. Evidence has been found for three new states in 10Be at excitation energies of 13.2, 14.8, and 16.1 MeV, which may be associated with a 4He+6He cluster structure. The evidence for He cluster states in 12Be in the excitation energy range 12 to 25 MeV is also discussed.

  20. Luminosity variations in several parallel auroral arcs before auroral breakup

    NASA Astrophysics Data System (ADS)

    Safargaleev, V.; Lyatsky, W.; Tagirov, V.

    1997-08-01

    Variation of the luminosity in two parallel auroral arcs before auroral breakup has been studied by using digitised TV-data with high temporal and spatial resolution. The intervals when a new arc appears near already existing one were chosen for analysis. It is shown, for all cases, that the appearance of a new arc is accompanied by fading or disappearance of another arc. We have named these events out-of-phase events, OP. Another type of luminosity variation is characterised by almost simultaneous enhancement of intensity in the both arcs (in-phase event, IP). The characteristic time of IP events is 10-20 s, whereas OP events last about one minute. Sometimes out-of-phase events begin as IP events. The possible mechanisms for OP and IP events are discussed.

  1. Stability of volcanic ash aggregates and break-up processes.

    PubMed

    Mueller, Sebastian B; Kueppers, Ulrich; Ametsbichler, Jonathan; Cimarelli, Corrado; Merrison, Jonathan P; Poret, Matthieu; Wadsworth, Fabian B; Dingwell, Donald B

    2017-08-07

    Numerical modeling of ash plume dispersal is an important tool for forecasting and mitigating potential hazards from volcanic ash erupted during explosive volcanism. Recent tephra dispersal models have been expanded to account for dynamic ash aggregation processes. However, there are very few studies on rates of disaggregation during transport. It follows that current models regard ash aggregation as irrevocable and may therefore overestimate aggregation-enhanced sedimentation. In this experimental study, we use industrial granulation techniques to artificially produce aggregates. We subject these to impact tests and evaluate their resistance to break-up processes. We find a dependence of aggregate stability on primary particle size distribution and solid particle binder concentration. We posit that our findings could be combined with eruption source parameters and implemented in future tephra dispersal models.

  2. Regenerative multi-pass beam breakup in two dimensions

    SciTech Connect

    Eduard Pozdeyev

    2004-12-01

    In this paper, a formula, describing a threshold of the regenerative multi-pass Beam Breakup (BBU) for a single dipole higher order mode with arbitrary polarization in a two-pass accelerator with a general-form, 4x4 recirculation matrix, is derived. Also a new two-dimensional BBU code is introduced. To illustrate specifics of the BBU in two dimensions, the formula is used to calculate the threshold in several cases including two-dimensional uncoupled optics, reflecting optics, and rotating optics. The analytical results are compared to results of simulation obtained with the new code. At the end of the paper, a mathematical relation between transfer matrices between cavities of the accelerating structure and recirculation matrices for each cavity, which must be satisfied in order to successfully suppress the BBU by reflection or rotation in several cavities, is presented.

  3. Gondwanan break-up: legacies of a lost world?

    PubMed

    Upchurch, Paul

    2008-04-01

    Fierce debate surrounds the history of organisms in the southern hemisphere; did Gondwanan break-up produce ocean barriers that imposed distribution patterns on phylogenies (vicariance)? Or have organisms modified their distributions through trans-oceanic dispersal? Recent advances in biogeographical theory suggest that the current focus on vicariance versus dispersal is too narrow because it ignores 'geodispersal' (i.e. expansion of species into areas when geographical barriers disappear), extinction and sampling errors. Geodispersal produces multiple, conflicting vicariance patterns, and extinction and sampling errors destroy vicariance patterns. This perspective suggests that it is more difficult to detect vicariance than trans-oceanic dispersal and that specialized methods must be applied if an unbiased understanding of southern hemisphere biogeography is to be achieved.

  4. Breakup of molten aluminum jets injected into water

    SciTech Connect

    Greene, G.A.; Finfrock, C.C.; Schwarz, C.E.; Hyder, M.L.

    1992-01-01

    A series of eighteen tests were performed to investigate the behavior of a molten jet of aluminum as it penetrates a deep pool of subcooled water. Jet penetration lengths required for breakup were found to agree with an existing model. Debris size and density were measured and are presented as a function of the jet diameter and water pool temperature. For those tests that exhibited the ability to spread across the steel baseplate under the water, the melt spreading behavior is compared to the existing melt spreading correlation. In the jet mode of melt-water contact, no explosive interactions were observed in these tests. Due to the nearly prototypical nature of these tests, it appears reasonable to conclude that gamma heating of non-fuel components during the DEGB-LOCA would, at worst, benignly melt some aluminum components in the reactor tank, resulting in large particles or debris formations which would remain in the tank and be coolable.

  5. Beam breakup in an advanced linear induction accelerator

    SciTech Connect

    Ekdahl, Carl August; Coleman, Joshua Eugene; McCuistian, Brian Trent

    2016-07-01

    Two linear induction accelerators (LIAs) have been in operation for a number of years at the Los Alamos Dual Axis Radiographic Hydrodynamic Test (DARHT) facility. A new multipulse LIA is being developed. We have computationally investigated the beam breakup (BBU) instability in this advanced LIA. In particular, we have explored the consequences of the choice of beam injector energy and the grouping of LIA cells. We find that within the limited range of options presently under consideration for the LIA architecture, there is little adverse effect on the BBU growth. The computational tool that we used for this investigation was the beam dynamics code linear accelerator model for DARHT (LAMDA). In conclusion, to confirm that LAMDA was appropriate for this task, we first validated it through comparisons with the experimental BBU data acquired on the DARHT accelerators.

  6. ReformAlign: improved multiple sequence alignments using a profile-based meta-alignment approach.

    PubMed

    Lyras, Dimitrios P; Metzler, Dirk

    2014-08-07

    Obtaining an accurate sequence alignment is fundamental for consistently analyzing biological data. Although this problem may be efficiently solved when only two sequences are considered, the exact inference of the optimal alignment easily gets computationally intractable for the multiple sequence alignment case. To cope with the high computational expenses, approximate heuristic methods have been proposed that address the problem indirectly by progressively aligning the sequences in pairs according to their relatedness. These methods however are not flexible to change the alignment of an already aligned group of sequences in the view of new data, resulting thus in compromises on the quality of the deriving alignment. In this paper we present ReformAlign, a novel meta-alignment approach that may significantly improve on the quality of the deriving alignments from popular aligners. We call ReformAlign a meta-aligner as it requires an initial alignment, for which a variety of alignment programs can be used. The main idea behind ReformAlign is quite straightforward: at first, an existing alignment is used to construct a standard profile which summarizes the initial alignment and then all sequences are individually re-aligned against the formed profile. From each sequence-profile comparison, the alignment of each sequence against the profile is recorded and the final alignment is indirectly inferred by merging all the individual sub-alignments into a unified set. The employment of ReformAlign may often result in alignments which are significantly more accurate than the starting alignments. We evaluated the effect of ReformAlign on the generated alignments from ten leading alignment methods using real data of variable size and sequence identity. The experimental results suggest that the proposed meta-aligner approach may often lead to statistically significant more accurate alignments. Furthermore, we show that ReformAlign results in more substantial improvement in

  7. Flow bursts, breakup arc, and substorm current wedge

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard

    2015-04-01

    Energy liberated by the reconnection process in the near-Earth tail is transported via flow bursts toward the dipolar magnetosphere during substorms. The breakup arc is a manifestation of the arrival of the bursts under flow braking and energy deposition. Its structure and behavior is analyzed on the basis of five striking spatial, temporal, and energetic properties, qualitatively and in part also quantitatively. A key element is the formation of stop layers. They are thin layers, of the width of an ion gyro radius, in which the magnetic field makes a transition from tail to near-dipolar magnetosphere configurations and in which the kinetic energy of fast flows is converted into electromagnetic energy of kinetic Alfvén waves. The flows arise from the relaxation of the strong magnetic shear stresses in the leading part of the flow bursts. The bright narrow arcs of less than 10 km width inside the broad poleward expanding breakup arc, Alfvénic in nature and visually characterized by erratic short-lived rays, are seen as traces of the stop layers. The gaps between two narrow and highly structured arcs are filled with more diffuse emissions. They are attributed to the relaxation of the less strained magnetic field of the flow bursts. Eastward flows along the arcs are linked to the shrinking gaps between two successive arcs and the entry of auroral streamers into the dipolar magnetosphere in the midnight sector. Flow braking in the stop layers forms multiple pairs of narrow balanced currents and cannot be behind the formation of the substorm current wedge. Instead, its origin is attributed to the force exerted by the dipolarized magnetic field of the flow bursts on the high-beta plasma, after the high magnetic shears have relaxed and the fast flows and stop layer process have subsided, in other words, to the "dying flow bursts."

  8. Correlating early evolution of parasitic platyhelminths to Gondwana breakup.

    PubMed

    Badets, Mathieu; Whittington, Ian; Lalubin, Fabrice; Allienne, Jean-Francois; Maspimby, Jean-Luc; Bentz, Sophie; Du Preez, Louis H; Barton, Diane; Hasegawa, Hideo; Tandon, Veena; Imkongwapang, Rangpenyuba; Imkongwapang, Rangpenyubai; Ohler, Annemarie; Combes, Claude; Verneau, Olivier

    2011-12-01

    Investigating patterns and processes of parasite diversification over ancient geological periods should involve comparisons of host and parasite phylogenies in a biogeographic context. It has been shown previously that the geographical distribution of host-specific parasites of sarcopterygians was guided, from Palaeozoic to Cainozoic times, mostly by evolution and diversification of their freshwater hosts. Here, we propose phylogenies of neobatrachian frogs and their specific parasites (Platyhelminthes, Monogenea) to investigate coevolutionary processes and historical biogeography of polystomes and further discuss all the possible assumptions that may account for the early evolution of these parasites. Phylogenetic analyses of concatenated rRNA nuclear genes (18S and partial 28S) supplemented by cophylogenetic and biogeographic vicariance analyses reveal four main parasite lineages that can be ascribed to centers of diversity, namely Australia, India, Africa, and South America. In addition, the relationships among these biogeographical monophyletic groups, substantiated by molecular dating, reflect sequential origins during the breakup of Gondwana. The Australian polystome lineage may have been isolated during the first stages of the breakup, whereas the Indian lineage would have arisen after the complete separation of western and eastern Gondwanan components. Next, polystomes would have codiverged with hyloid sensu stricto and ranoid frog lineages before the completion of South American and African plate separation. Ultimately, they would have undergone an extensive diversification in South America when their ancestral host families diversified. Therefore, the presence of polystome parasites in specific anuran host clades and in discrete geographic areas reveals the importance of biogeographic vicariance in diversification processes and supports the occurrence and radiation of amphibians over ancient and recent geological periods.

  9. Alignment of tactical tropo antennas

    NASA Astrophysics Data System (ADS)

    Bradley, Philip A.

    1986-07-01

    Alignment problems of parabolic reflector antennas for troposcatter radio communications are analyzed. Defects of previous alignment techniques are delineated and a new technique for automatic antenna alignment is presented.

  10. How to identify oceanic crust-Evidence for a complex break-up in the Mozambique Channel, off East Africa

    NASA Astrophysics Data System (ADS)

    Klimke, Jennifer; Franke, Dieter; Gaedicke, Christoph; Schreckenberger, Bernd; Schnabel, Michael; Stollhofen, Harald; Rose, Jens; Chaheire, Mohamed

    2016-12-01

    The identification of oceanic crust at rifted margins plays a crucial role in academic research understanding rifting mechanisms and the architecture of continent-ocean boundaries, and is also important for hydrocarbon exploration extending into deeper water. In this paper, we provide a workflow for the determination of the crustal nature in the Mozambique Channel, east of Davie Ridge, by presenting a compilation of several geophysical attributes of oceanic crust at divergent margins. Previous reconstructions locate the Davie Ridge at the trace of a transform fault, along which Madagascar drifted to the south during the breakup of Gondwana. This implies a sharp transition from continental to oceanic crust seaward of Davie Ridge. Using new multichannel seismic profiles offshore northern Mozambique, we are able to identify distinct portions of stretched basement east of Davie Ridge. Two phases of deformation affecting the basement are observed, with the initial phase resulting in the formation of rotated fault blocks bounded by listric faults. Half-grabens are filled with wedge-shaped, syn-extensional sediments overlain by a prominent unconformity that northward merges with the top of highly reflective, mildly deformed basement, interpreted as oceanic crust. The second phase of deformation is associated with wrench faulting and probably correlates with the southward drift of Madagascar, which implies that the preceding phase affected basement generated or modified prior to the opening of the West Somali Basin. We conclude that the basement is unlikely to consist of normal oceanic crust and suggest that the first extensional phase corresponds to rifting between Madagascar and Africa. We find evidence for a wide area affected by strike-slip deformation, in contrast to the earlier proposed major single transform fault in the vicinity of Davie Ridge and suggest that the Mozambique Channel area to the north of Madagascar may be classified as an oblique rather than sheared

  11. Alignment of CEBAF cryomodules

    SciTech Connect

    Schneider, W.J.; Bisognano, J.J.; Fischer, J.

    1993-06-01

    CEBAF, the Continuous Electron Beam Accelerator Facility, when completed, will house a 4 GeV recirculating accelerator. Each of the accelerator`s two linacs contains 160 superconducting radio frequency (SRF) 1497 MHz niobium cavities in 20 cryomodules. Alignments of the cavities within the cryomodule with respect to beam axis is critical to achieving the optimum accelerator performance. This paper discusses the rationale for the current specification on cavity mechanical alignment: 2 mrad (rms) applied to the 0.5 m active length cavities. We describe the tooling that was developed to achieve the tolerance at the time of cavity pair assembly, to preserve and integrate alignment during cryomodule assembly, and to translate alignment to appropriate installation in the beam line.

  12. Parental break-ups and stress: roles of age & family structure in 44 509 pre-adolescent children.

    PubMed

    Dissing, Agnete S; Dich, Nadya; Andersen, Anne-Marie Nybo; Lund, Rikke; Rod, Naja H

    2017-10-01

    Parental break-up is wide spread, and the effects of parental break-up on children's well-being are known. The evidence regarding child age at break-up and subsequent family arrangements is inconclusive. Aim: to estimate the effects of parental break-up on stress in pre-adolescent children with a specific focus on age at break-up and post-breakup family arrangements. We used data from the Danish National Birth Cohort. Participants included 44 509 children followed from birth to age 11. Stress was self-reported by children at age 11, when the children also reported on parental break-up and post break-up family arrangements. Twenty-one percent of the children had experienced a parental break-up at age 11, and those who had experienced parental break-up showed a higher risk of stress (OR:1.72, 95%CI:1.55;1.91) regardless of the child's age at break-up. Children living in a new family with stepparents (OR = 1.63, 95%CI:1.38;1.92), or shared between the parents (OR = 1.48, 95%CI:1.26;1.75) reported higher stress than children of intact families. Single parent families reported markedly higher stress levels than children in intact families (OR = 2.18, 95%CI:1.90;2.50) and all other family types. Children who were satisfied with their living arrangements post-break-up reported the same stress level as children living in intact families (OR = 1.01, 95%CI:0.86;1.18). Children who experience parental break-up have higher stress levels, also many years after the break-up, and those living in a single parent household post break-up seem to be most vulnerable. Living arrangements post-breakup should be further investigated as a potential protective factor.

  13. Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

    DOE PAGES

    Kaercher, Pamela M.; Zepeda-Alarcon, Eloisa; Prakapenka, Vitali B.; ...

    2014-11-07

    Although the crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, little is known about the development of crystallographic preferred orientation (CPO) during deformation in stishovite. Insight into CPO and associated deformation mechanics of stishovite would provide important information for understanding subduction of quartz-bearing crustal rocks into the mantle. To study CPO development, we converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. We collected diffraction patterns in radial geometry to examine in situ development of crystallographic preferred orientation andmore » find that (001) poles preferentially align with the compression direction. Viscoplastic self-consistent modeling suggests the most likely slip systems at high pressure and ambient temperature are pyramidal and basal slip.« less

  14. Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

    SciTech Connect

    Kaercher, Pamela M.; Zepeda-Alarcon, Eloisa; Prakapenka, Vitali B.; Kanitpanyacharoen, Waruntorn; Smith, Jesse S.; Sinogeikin, Stanislav; Wenk, Hans-Rudolf

    2014-11-07

    Although the crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, little is known about the development of crystallographic preferred orientation (CPO) during deformation in stishovite. Insight into CPO and associated deformation mechanics of stishovite would provide important information for understanding subduction of quartz-bearing crustal rocks into the mantle. To study CPO development, we converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. We collected diffraction patterns in radial geometry to examine in situ development of crystallographic preferred orientation and find that (001) poles preferentially align with the compression direction. Viscoplastic self-consistent modeling suggests the most likely slip systems at high pressure and ambient temperature are pyramidal and basal slip.

  15. Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

    NASA Astrophysics Data System (ADS)

    Kaercher, Pamela M.; Zepeda-Alarcon, Eloisa; Prakapenka, Vitali B.; Kanitpanyacharoen, Waruntorn; Smith, Jesse S.; Sinogeikin, Stanislav; Wenk, Hans-Rudolf

    2015-04-01

    Although the crystal structure of the high-pressure SiO2 polymorph stishovite has been studied in detail, little is known about the development of crystallographic preferred orientation (CPO) during deformation in stishovite. Insight into CPO and associated deformation mechanics of stishovite would provide important information for understanding subduction of quartz-bearing crustal rocks into the mantle. To study CPO development, we converted a natural sample of flint to stishovite in a laser-heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. We collected diffraction patterns in radial geometry to examine in situ development of crystallographic preferred orientation and find that (001) poles preferentially align with the compression direction. Viscoplastic self-consistent modeling suggests the most likely slip systems at high pressure and ambient temperature are pyramidal and basal slip.

  16. Pairwise Sequence Alignment Library

    SciTech Connect

    Jeff Daily, PNNL

    2015-05-20

    Vector extensions, such as SSE, have been part of the x86 CPU since the 1990s, with applications in graphics, signal processing, and scientific applications. Although many algorithms and applications can naturally benefit from automatic vectorization techniques, there are still many that are difficult to vectorize due to their dependence on irregular data structures, dense branch operations, or data dependencies. Sequence alignment, one of the most widely used operations in bioinformatics workflows, has a computational footprint that features complex data dependencies. The trend of widening vector registers adversely affects the state-of-the-art sequence alignment algorithm based on striped data layouts. Therefore, a novel SIMD implementation of a parallel scan-based sequence alignment algorithm that can better exploit wider SIMD units was implemented as part of the Parallel Sequence Alignment Library (parasail). Parasail features: Reference implementations of all known vectorized sequence alignment approaches. Implementations of Smith Waterman (SW), semi-global (SG), and Needleman Wunsch (NW) sequence alignment algorithms. Implementations across all modern CPU instruction sets including AVX2 and KNC. Language interfaces for C/C++ and Python.

  17. Evidence of recent warming and El Nino-related variations in ice breakup of Wisconsin lakes

    USGS Publications Warehouse

    Anderson, W.L.; Robertson, D.M.; Magnuson, J.J.

    1996-01-01

    Ice breakup dates from 1968 to 1988 were examined for 20 Wisconsin lakes to determine whether consistent interannual and long-term changes exist. Each ice record had a trend toward earlier breakup dates, as demonstrated by a negative slope with time, indicating a recent warming trend. The average change in breakup dates was 0.82 d earlier per year for the lakes in southern Wisconsin, which was more extreme than that for the northern Wisconsin lakes (0.45 d yr-1). Interannual variation in breakup dates was related to the warm phase of El Nino/Southern Oscillation (ENSO) episodes. El Nino events occurred five times during this period (1965, 1972, 1976, 1982, and 1986). Average breakup dates were significantly earlier than average (5-14 d) during the mature phase of El Nino. This variability was affected by the location of the lake: El Nino-related variation was more evident for the southern lakes than the northern lakes. This difference was caused by the average date of breakup for the southern lakes being in late March directly following the period when air temperatures were strongly related to El Nino events, whereas the average dates of breakup of the northern lakes was in mid- to late April following a period when air temperatures were not significantly related to El Nino events. Overall, the interannual and long-term patterns across Wisconsin were relatively consistent, indicating that recent warming and El Nino- related variation are regional climatic responses.

  18. Large-scale climate controls of Interior Alaska river ice breakup

    NASA Astrophysics Data System (ADS)

    Newman, D.; Bieniek, P. A.; Bhatt, U. S.; Rundquist, L.; Lindsey, S.; Zhang, X.; Thoman, R.

    2010-12-01

    Frozen rivers in the Arctic serve as critical highways due to lack of roads, therefore it is important to understand the key mechanisms that control the timing of river ice breakup. The relationships between springtime Interior Alaska river ice breakup date and the large-scale climate are investigated for the Yukon, Tanana, Kuskokwim, and Chena Rivers for the 1949-2008 period. The most important climate factor that determines breakup is April-May surface air temperatures (SATs). Breakup tends to occur earlier when Alaska April-May SATs and river flow are above normal. Spring SATs are influenced by storms approaching the state from the Gulf of Alaska, which are part of large-scale climate anomalies that compare favorably with ENSO. During the warm phase of ENSO fewer storms travel into the Gulf of Alaska during the spring, resulting in a decrease of cloud cover over Alaska, which increases surface solar insolation. This results in warmer than average springtime SATs and an earlier breakup date. The opposite holds true for the cold phase of ENSO. Increased wintertime precipitation over Alaska has a secondary impact on earlier breakup by increasing spring river discharge. Improved springtime Alaska temperature predictions would enhance the ability to forecast river ice breakup timing.

  19. The Effect of Surfactants on the Breakup of an Axisymmetric Laminar Jet

    NASA Astrophysics Data System (ADS)

    Walker, Justin; Calabrese, Richard

    2011-11-01

    The breakup of a laminar axisymmetric jet is a well-studied fluid dynamics phenomenon, first studied by Savart (1833) and Rayleigh (1879). Many papers have been published over the years describing the theory of jet breakup, such as the paper by Tomotika (1935). More recently, many studies have been performed using various computational simulations to better understand the mechanics of jet breakup, notable among these are Homma et al. (2006). Despite the extensive literature on the topic, the impact of surface active agents on jet breakup has received limited attention, whether due to the system's inherent complexity or a poor understanding of the mechanics of the action of surface active agents themselves. In this study, the drop size distribution and jet breakup length resulting from the breakup of liquid jet systems were studied experimentally. Jets were formed by forcing a fluid through a narrow capillary using pneumatic pressure. Experiments involving oil-water jets with aqueous surfactants were performed. Several distinct regimes were identified based on hydrodynamic and physicochemical conditions. Jet length was found to increase with surfactant concentration, while droplet diameter was found to decrease (dependent on jet regime). A Semiempirical model to predict the breakup length of Jets in the presence of surfactants is also proposed.

  20. A consistent definition of the Arctic polar vortex breakup in both the lower and upper stratosphere

    NASA Astrophysics Data System (ADS)

    Choi, W.; Seo, J.

    2014-12-01

    Breakup of the polar vortex is a dominant feature of the seasonal transition from winter to summer in the stratosphere, which significantly affects stratospheric O3 concentration and tropospheric weather. Previously several criteria for the vortex breakup have been suggested based on the potential vorticity (PV) and wind speed, however, those mainly have focused on the lower stratospheric vortex of which spatiotemporal evolution and decay are more continuous than those of the upper stratospheric vortex. To find a consistent criterion for the vortex breakup in both the lower and upper stratosphere, the present study defined a polar vortex breakup day as when PV gradient at the polar vortex edge becomes lower than that at the subtropical edge on the area equivalent latitude based on PV. With applying the new definition to the UK Met Office reanalysis data, the breakup days of the Arctic polar vortices on 18 isentropic levels from 450 K to 1300 K were calculated for the period of 1993-2005. In comparison with CH4, N2O and O3 measured by the ILAS and POAM II/III satellite instruments, the breakup days are well consistent with changes in the distribution of such tracers as well as their zonal standard deviations associated with the vortex structure breaking and irreversible mixing. The vortex breakup in the upper stratosphere occurs more or less a month prior to that in the middle and lower stratosphere while the stratospheric final warming events occurs simultaneously in the upper and lower stratosphere.

  1. Substorm simulation: Quiet and N-S arcs preceding auroral breakup

    NASA Astrophysics Data System (ADS)

    Ebihara, Y.; Tanaka, T.

    2016-02-01

    Auroral breakup at the onset of substorm expansion is sometimes preceded by auroral forms known as quiet arcs and N-S arcs. Observations have shown that both the auroral forms tend to move equatorward, and the initial brightening takes place in or near one of the quiet arcs. The auroral forms attract great attention, but generation of auroral forms and their association with the initial brightening are poorly understood. Recent global magnetohydrodynamic simulations are capable of producing upward field-aligned currents (FACs) that resemble the auroral forms in both shape and temporal evolution. Based on the simulation results, we propose the following scenarios: (1) When the convection electric field is weak (northward interplanetary magnetic field (IMF)), the high-pressure region is elongated from the plasma sheet toward higher latitudes and is structured by a coupling between the magnetosphere and the ionosphere (interchange-like instabilities). (2) When the convection electric field is strong (southward IMF), the structured high-pressure region moves equatorward (toward the plasma sheet). Upward currents are generated around it, which can be observed as arcs in the ionosphere. The upward current can be tentatively intensified in the course of the equatorward movement before the formation of a near-Earth neutral line (NENL). (3) The NENL releases magnetic tension and results in the enhancement of plasma pressure at off-equator in the near-Earth region. Sudden formation of the off-equatorial high-pressure region generates the onset current system that manifests initial brightening. Our scenario can explain the observational fact that poleward arcs remained undisturbed at the onset.

  2. Changes in spinal alignment.

    PubMed

    Veintemillas Aráiz, M T; Beltrán Salazar, V P; Rivera Valladares, L; Marín Aznar, A; Melloni Ribas, P; Valls Pascual, R

    2016-04-01

    Spinal misalignments are a common reason for consultation at primary care centers and specialized departments. Misalignment has diverse causes and is influenced by multiple factors: in adolescence, the most frequent misalignment is scoliosis, which is idiopathic in 80% of cases and normally asymptomatic. In adults, the most common cause is degenerative. It is important to know the natural history and to detect factors that might predict progression. The correct diagnosis of spinal deformities requires specific imaging studies. The degree of deformity determines the type of treatment. The aim is to prevent progression of the deformity and to recover the flexibility and balance of the body.

  3. PDV Probe Alignment Technique

    SciTech Connect

    Whitworth, T L; May, C M; Strand, O T

    2007-10-26

    This alignment technique was developed while performing heterodyne velocimetry measurements at LLNL. There are a few minor items needed, such as a white card with aperture in center, visible alignment laser, IR back reflection meter, and a microscope to view the bridge surface. The work was performed on KCP flyers that were 6 and 8 mils wide. The probes used were Oz Optics manufactured with focal distances of 42mm and 26mm. Both probes provide a spot size of approximately 80?m at 1550nm. The 42mm probes were specified to provide an internal back reflection of -35 to -40dB, and the probe back reflections were measured to be -37dB and -33dB. The 26mm probes were specified as -30dB and both measured -30.5dB. The probe is initially aligned normal to the flyer/bridge surface. This provides a very high return signal, up to -2dB, due to the bridge reflectivity. A white card with a hole in the center as an aperture can be used to check the reflected beam position relative to the probe and launch beam, and the alignment laser spot centered on the bridge, see Figure 1 and Figure 2. The IR back reflection meter is used to measure the dB return from the probe and surface, and a white card or similar object is inserted between the probe and surface to block surface reflection. It may take several iterations between the visible alignment laser and the IR back reflection meter to complete this alignment procedure. Once aligned normal to the surface, the probe should be tilted to position the visible alignment beam as shown in Figure 3, and the flyer should be translated in the X and Y axis to reposition the alignment beam onto the flyer as shown in Figure 4. This tilting of the probe minimizes the amount of light from the bridge reflection into the fiber within the probe while maintaining the alignment as near normal to the flyer surface as possible. When the back reflection is measured after the tilt adjustment, the level should be about -3dB to -6dB higher than the probes

  4. Bunionette deformity.

    PubMed

    Cohen, Bruce E; Nicholson, Christopher W

    2007-05-01

    The bunionette, or tailor's bunion, is a lateral prominence of the fifth metatarsal head. Most commonly, bunionettes are the result of a widened 4-5 intermetatarsal angle with associated varus of the metatarsophalangeal joint. When symptomatic, these deformities often respond to nonsurgical treatment methods, such as wider shoes and padding techniques. When these methods are unsuccessful, surgical treatment is based on preoperative radiographs and associated lesions, such as hyperkeratoses. In rare situations, a simple lateral eminence resection is appropriate; however, the risk of recurrence or overresection is high with this technique. Patients with a lateral bow to the fifth metatarsal are treated with a distal chevron-type osteotomy. A widened 4-5 intermetatarsal angle often requires a diaphyseal osteotomy for correction.

  5. Neutron Halo Structure at the Limit of Stability Probed by Breakup Reactions

    NASA Astrophysics Data System (ADS)

    Nakamura, Takashi

    2013-08-01

    Atomic nuclei along the neutron drip line are investigated experimentally by breakup reactions of the rare isotope beams. Such exotic nuclei often show the neutron halo structure, which is the main focus of this paper. Characteristic features of the Coulomb and nuclear breakup at intermediate to high incident energies are described. Then, recent experimental results on halo nuclei, mainly on 31Ne, obtained at the new-generation RI-beam facility, RIBF (RI Beam factory) at RIKEN, are presented. Perspectives for the breakup experiments using the new facility SAMURAI at RIBF ara also discussed.

  6. Measurements of the breakup and neutron removal cross sections for {sup 16}C

    SciTech Connect

    Ashwood, N. I.; Freer, M.; Clarke, N.M.; Curtis, N.; Soic, N.; Ziman, V.A.; Angelique, J.C.; Lecouey, J.L.; Marques, F.M.; Normand, G.; Orr, N.A.; Timis, C.; Bouchat, V.; Hanappe, F.; Kerckx, Y.; Materna, T.; Catford, W.N.; Dorvaux, O.; Stuttge, L.

    2004-12-01

    Measurements of the breakup and the neutron removal reactions of {sup 16}C have been made at 46 MeV/A and the decay cross sections measured. A correlation between the cluster breakup channels and the reaction Q value suggests that the reaction mechanism is strongly linked to quasielastic processes. No enhancement of the two-body cluster breakup cross section is seen for {sup 16}C. This result would indicate that {sup 16}C does not have a well developed cluster structure in the ground state, in agreement with recent calculations.

  7. Isomer ratio measurements as a probe of the dynamics of breakup and incomplete fusion

    SciTech Connect

    Gasques, L. R.; Dasgupta, M.; Hinde, D. J.; Peatey, T.; Diaz-Torres, A.; Newton, J. O.

    2006-12-15

    The incomplete fusion mechanism following breakup of {sup 6,7}Li and {sup 9}Be projectiles incident on targets of {sup 209}Bi and {sup 208}Pb is investigated through isomer ratio measurements for the {sup 212}At and {sup 211}Po products. The phenomenological analysis presented in this paper indicates that incomplete fusion brings relatively more angular momentum into the system than equivalent reactions with a direct beam of the fused fragment. This is attributed to the trajectories of breakup fragments. Calculations with a 3D classical trajectory model support this. Isomer ratio measurements for incomplete fusion reactions can provide a test of new theoretical models of breakup and fusion.

  8. Characterization of jet breakup mechanisms observed from simulant experiments of molten fuel penetrating coolant

    SciTech Connect

    Jones, B.G.

    1992-01-01

    The goal of this research program has been to add to our understanding of the breakup of molten fuel jets penetrating reactor coolant. Easily handled working fluids are used to simulate fuel jet breakup, so that detailed observations may be obtained from a relatively large number of experiments. The tools used for observing this behavior are high speed notion picture photography, Flash X-radiography, and X-ray cine. Jet breakup lengths are determined from motion pictures; the mechanisms by which the jets are fragmented may be inferred from radiographs.

  9. Breakup of shearless meanders and ``outer'' tori in the standard nontwist map

    NASA Astrophysics Data System (ADS)

    Fuchss, K.; Wurm, A.; Apte, A.; Morrison, P. J.

    2006-09-01

    The breakup of shearless invariant tori with winding number ω =(11+γ)/(12+γ) (in continued fraction representation) of the standard nontwist map is studied numerically using Greene's residue criterion. Tori of this winding number can assume the shape of meanders [folded-over invariant tori which are not graphs over the x axis in (x,y) phase space], whose breakup is the first point of focus here. Secondly, multiple shearless orbits of this winding number can exist, leading to a new type of breakup scenario. Results are discussed within the framework of the renormalization group for area-preserving maps. Regularity of the critical tori is also investigated.

  10. Coulomb-nuclear interference in 56 MeV deuteron breakup at extreme forward angle

    NASA Astrophysics Data System (ADS)

    Samanta, C.; Kanungo, Rituparna; Mukherjee, Sanjukta; Basu, D. N.

    1995-02-01

    Recently measured 12C(d,pn) 12C breakup data show a dip in the energy integrated cross section below a momentum transfer ∼ 117 MeV/ c. We analyse these data by the prior form distorted-wave Born approximation theory. Although the double humped structure of the θp = θn = 0° data exhibit the dominance of Coulomb-breakup, the pronounced asymmetry of the energy sharing data cannot be explained through Coulomb breakup only. A closer agreement to the data is obtained through Coulomb-nuclear interference and an unusual optical potential of longer range in the exit channel.

  11. Elastic and break-up of the 1n-halo 11Be nucleus

    NASA Astrophysics Data System (ADS)

    Di Pietro, A.; Moro, A. M.; Acosta, L.; Amorini, F.; Borge, M. J. G.; Figuera, P.; Fisichella, M.; Fraile, L. M.; Gomez-Camacho, J.; Jeppesen, H.; Lattuada, M.; Martel, I.; Milin, M.; Musumarra, A.; Papa, M.; Pellegriti, M. G.; Perez-Bernal, F.; Raabe, R.; Randisi, G.; Rizzo, F.; Scuderi, V.; Tengblad, O.; Torresi, D.; Vidal, A. Maira; Voulot, D.; Wenander, F.; Zadro, M.

    2014-03-01

    The elastic and break-up angular distributions of the 10,11Be+64Zn reactions measured at Ec.m.≈1.4 VC have been analysed within the CCDC and O.M. frameworks. The suppression of the Coulomb-nuclear interference, observed in the 11Be scattering case with respect to the 10Be, has been interpreted as due to a long range absorption owing to the coupling with the break-up (Coulomb and nuclear) channels. The presence of 10Be events on the 11Be experiment data have been explained as due mainly to break-up processes.

  12. Curriculum Alignment Research Suggests that Alignment Can Improve Student Achievement

    ERIC Educational Resources Information Center

    Squires, David

    2012-01-01

    Curriculum alignment research has developed showing the relationship among three alignment categories: the taught curriculum, the tested curriculum and the written curriculum. Each pair (for example, the taught and the written curriculum) shows a positive impact for aligning those results. Following this, alignment results from the Third…

  13. Curriculum Alignment Research Suggests that Alignment Can Improve Student Achievement

    ERIC Educational Resources Information Center

    Squires, David

    2012-01-01

    Curriculum alignment research has developed showing the relationship among three alignment categories: the taught curriculum, the tested curriculum and the written curriculum. Each pair (for example, the taught and the written curriculum) shows a positive impact for aligning those results. Following this, alignment results from the Third…

  14. Imaging continental breakup using teleseismic body waves: The Woodlark Rift, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Eilon, Zachary; Abers, Geoffrey A.; Gaherty, James B.; Jin, Ge

    2015-09-01

    This study images the upper mantle beneath the D'Entrecasteax Islands, Papua New Guinea, providing insight into mantle deformation beneath a highly rifted continent adjacent to propagating spreading centers. Differential travel times from P and S-wave teleseisms recorded during the 2010-2011 CDPapua passive seismic experiment are used to invert for separate VP and VS velocity models of the continental rift. A low-velocity structure marks the E-W axis of the rift, correlating with the thinnest crust, high heat flow, and a linear trend of volcanoes. This slow region extends 250 km along strike from the oceanic spreading centers, demonstrating significant mantle extension ahead of seafloor breakup. The rift remains narrow to depth indicating localization of extension, perhaps as a result of mantle hydration. A high-VP structure at depths of 90-120 km beneath the north of the array is more than 6.5% faster than the rift axis and contains well-located intermediate depth earthquakes. These independent observations place firm constraints on the lateral thermal contrast at depth between the rift axis and cold lithosphere to the north that may be related to recent subduction, although the polarity of subduction cannot be resolved. This geometry is gravitationally unstable; downwelling or small-scale convection could have facilitated rifting and rapid lithospheric removal, although this may require a wet mantle to be realistic on the required time scales. The high-V structure agrees with the maximum P,T conditions recorded by young ultra-high pressure rocks exposed on the rift axis and may be implicated in their genesis.

  15. Dislocation mediated alignment during metal nanoparticle coalescence

    DOE PAGES

    Lange, A. P.; Samanta, A.; Majidi, H.; ...

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leadingmore » to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  16. Dislocation mediated alignment during metal nanoparticle coalescence

    SciTech Connect

    Lange, A. P.; Samanta, A.; Majidi, H.; Mahajan, S.; Ging, J.; Olson, T. Y.; van Benthem, K.; Elhadj, S.

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leading to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  17. Dislocation mediated alignment during metal nanoparticle coalescence

    SciTech Connect

    Lange, A. P.; Samanta, A.; Majidi, H.; Mahajan, S.; Ging, J.; Olson, T. Y.; van Benthem, K.; Elhadj, S.

    2016-09-13

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (~315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leading to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. As a result, this constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results

  18. Quantification of abdominal aortic deformation after EVAR

    NASA Astrophysics Data System (ADS)

    Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

    2009-02-01

    Quantification of abdominal aortic deformation is an important requirement for the evaluation of endovascular stenting procedures and the further refinement of stent graft design. During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and, the stent graft. This deformation can affect the flow characteristics and morphology of the aorta which have been shown to be elicitors for stent graft failures and be reason for reappearance of aneurysms. We present a method for quantifying the deformation of an aneurysmatic aorta imposed by an inserted stent graft device. The outline of the procedure includes initial rigid alignment of the two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. This is accomplished by preprocessing and remodeling of the pre- and postoperative aortic shapes before performing a non-rigid registration. We further narrow the resulting displacement fields to only include local non-rigid deformation and therefore, eliminate all remaining global rigid transformations. Finally, deformations for specified locations can be calculated from the resulting displacement fields. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results and evaluation of the usage of deformation quantification were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

  19. Early breakup of Gondwana: constraints from global plate motion models

    NASA Astrophysics Data System (ADS)

    Seton, Maria; Zahirovic, Sabin; Williams, Simon; Whittaker, Joanne; Gibbons, Ana; Muller, Dietmar; Brune, Sascha; Heine, Christian

    2015-04-01

    Supercontinent break-up and amalgamation is a fundamental Earth cycle, contributing to long-term sea-level fluctuations, species diversity and extinction events, long-term greenhouse-icehouse cycles and changes in the long-wavelength density structure of the mantle. The most recent and best-constrained example involves the fragmentation of Gondwana, starting with rifting between Africa/Madagascar and Antarctica in the Early Jurassic and ending with the separation of the Lord Howe microcontinental blocks east of Australia in the Late Cretaceous. Although the first order configuration of Gondwana within modern reconstructions appears similar to that first proposed by Wegener a century ago, recent studies utilising a wealth of new geophysical and geological data provide a much more detailed picture of relative plate motions both during rifting and subsequent seafloor spreading. We present our latest global plate motion model that includes extensive, new regional analyses. These include: South Atlantic rifting, which started at 150 Ma and propagated into cratonic Africa by 145 Ma (Heine et al., 2013); rifting and early seafloor spreading between Australia, India and Antarctica, which reconciles the fit between Broken Ridge-Kergulean Plateau and the eastern Tasman region (Whittaker et al., 2013); rifting of continental material from northeastern Gondwana and its accretion onto Eurasia and SE Asia including a new model of microcontinent formation and early seafloor spreading in the eastern Indian Ocean (Gibbons et al., 2012; 2013; in review; Williams et al., 2013; Zahirovic et al., 2014); and a new model for the isolation of Zealandia east of Australia, with rifting initiating at 100 Ma until the start of seafloor spreading in the Tasman Sea at ~85 Ma (Williams et al., in prep). Using these reconstructions within the open-source GPlates software, accompanied by a set of evolving plates and plate boundaries, we can explore the factors that govern the behavior of plate

  20. Pulsation tectonics as the control of continental breakup

    NASA Astrophysics Data System (ADS)

    Sheridan, Robert E.

    1987-11-01

    New data from the recent IPOD drilling of DSDP Site 534 in the Blake-Bahama Basin give a definitive age for the spreading-center shift involved in the breakup of the North American Atlantic margin. A basal Callovian age (~155 m.y.) is determined for the Blake Spur anomaly marking this spreading-center shift that signals the birth of the modern North Atlantic Ocean. This is some 20 m.y. younger than previously thought. One implication of this result is that this spreading-center shift starting North Atlantic breakup is now of an age which could be assigned to the spreading-center shift needed to end the rifting in the Gulf of Mexico. It is suggested that this might be one and the same event. Another implication of this younger age for the Blake Spur event is that relatively high spreading rates are now required for the Jurassic outer magnetic quiet zone along the North American margin. This association of a relatively high spreading rate with a magnetic quiet zone is similar to that for the mid-Cretaceous and implies a link between the processes controlling plate spreading, which are in the upper mantle, and the processes controlling the magnetic field, which are in the outer core. The cycles of fast and slow spreading and quiet and reversing magnetic field have a period of 60-100 m.y. A theory of pulsation tectonics involving the cyclic eruption of plumes of hot mantle material from the lowermost D″ layer of the mantle could explain the correlation. Plumes carry heat away from the core/mantle boundary and later reach the asthenosphere and lithosphere to induce faster spreading. The pulse of fast spreading in the Jurassic apparently caused the breakup of the North Atlantic. Other pulses of fast spreading appear to correlate with major ocean openings on various parts of the globe, implying that this might be a prevalent process. I suggest rifting of passive margins may be controlled by the more fundamental global processes described by the theory of pulsation

  1. Curious Fluid Flows: From Complex Fluid Breakup to Helium Wetting

    NASA Astrophysics Data System (ADS)

    Huisman, Fawn Mitsu

    This work encompasses three projects; pinch-off dynamics in non-Newtonian fluids; helium wetting on alkali metals; and the investigation of quartz tuning forks as cryogenic pressure transducers. Chapter 1 discusses the breakup of a non-Newtonian yield stress fluid bridge. We measured the minimum neck radius, hmin, as a function of time and fit it to a power law with exponent n 1. We then compare n1 to exponent n2, obtained from a rotational rheometer using a Herschel-Bulkley model. We confirm n1=n2 for the widest variety of non-Newtonian fluids to date. When these fluids are diluted with a Newtonian fluid n1 does not equal n2. No current models predict that behavior, identifying a new class of fluid breakup. Chapter 2 presents the first chemical potential-temperature phase diagram of helium on lithium, sodium and gold, using a novel pressure measurement system. The growth and superfluid transition of a helium film on these substrates is measured via an oscillator for isotherms (fixed temperature, varying amount of helium gas), and quenches (fixed amount of helium gas, varying temperature). The chemical potential-temperature plot is similar for gold, lithium and sodium despite the large difference in the substrate binding energies. No signs of a 2-D liquid-vapor transition were seen. Chapter 3 discusses the creation of a 32.768 kHz quartz tuning fork in situ pressure transducer. Tuning forks are used to measure pressure at room temperature, but no work addresses their potential as cryogenic pressure transducers. We mapped out the behavior of a tuning fork as a function of pressure at 298, 7.0, 2.5, 1.6, 1.0 and 0.7 K by measuring the quality factor. The fork is sensitive to pressures above 0.1 mTorr, limiting its use as a pressure gauge at 0.6 K and below. The experimental curves were compared to a theoretical Q(P, T) function that was refined using the 298 K data. At cryogenic temperatures the formula breaks down in the viscous region and becomes inaccurate. The

  2. Breakup of an electrified viscous thread with charged surfactants

    NASA Astrophysics Data System (ADS)

    Conroy, D. T.; Matar, O. K.; Craster, R. V.; Papageorgiou, D. T.

    2011-02-01

    The dynamics and breakup of electrified viscous jets in the presence of ionic surfactants at the interface are investigated theoretically. Axisymmetric configurations are considered and the jet is surrounded by a concentrically placed cylindrical electrode, which is held at a constant voltage potential. The annular region between the jet and the electrode is taken to be a hydrodynamically passive dielectric medium and an electric field is set up there and drives the flow, along with other physical mechanisms including capillary instability and viscous effects. The jet fluid is taken to be a symmetric electrolyte and proper modeling of the cationic and anionic species is used by considering the Nernst-Planck equations in order to find the volume charge density that influences the electric field in the jet. A positively charged insoluble surfactant is present at the interface, and its evolution, as well as the resulting value of the local surface tension coefficient, is coupled with the voltage potential at the interface. The resulting coupled nonlinear systems are derived and analytical progress is made by carrying out a nonlinear slender jet approximation. The reduced model is described by a number of hydrodynamic, electrical, and electrokinetic parameters, and an extensive computational study is undertaken to elucidate the dynamics along with allied linear properties. It is established that the jet ruptures in finite time provided the outer electrode is sufficiently far away, and numerous examples are given where the dimensionless parameters can be used to control the size of the satellite drops that form beyond the topological transition, as well as the time to break up. It is also shown that pinching solutions follow the self-similar dynamics of clean viscous jets at times close to the breakup time. Finally, a further asymptotic theory is developed for large Debye layers to produce an additional model that incorporates the effects of surface charge diffusion

  3. Alignment and nonlinear elasticity in biopolymer gels.

    PubMed

    Feng, Jingchen; Levine, Herbert; Mao, Xiaoming; Sander, Leonard M

    2015-04-01

    We present a Landau-type theory for the nonlinear elasticity of biopolymer gels with a part of the order parameter describing induced nematic order of fibers in the gel. We attribute the nonlinear elastic behavior of these materials to fiber alignment induced by strain. We suggest an application to contact guidance of cell motility in tissue. We compare our theory to simulation of a disordered lattice model for biopolymers. We treat homogeneous deformations such as simple shear, hydrostatic expansion, and simple extension, and obtain good agreement between theory and simulation. We also consider a localized perturbation which is a simple model for a contracting cell in a medium.

  4. The influence of inherited structures on dyke emplacement during Gondwana break-up in southwestern Africa

    NASA Astrophysics Data System (ADS)

    Will, Thomas; Frimmel, Hartwig

    2013-04-01

    A kinematic analysis of Cretaceous and pre-Cretaceous faulting and fracturing was carried out along the west coast of Southern Africa extending from the greater Cape Town area to the Orange River and beyond into southern Namibia. This study was augmented by the geometric analysis of mainly Cretaceous mafic dykes exposed from SW Angola to the southern tip of Africa. The kinematic analysis shows that the Cretaceous rifting event that led to the opening of the modern South Atlantic was largely controlled by NW-SE and NE-SW-striking structures. In the coastal areas of South Africa the Cretaceous deformation was dominated by NE-SW extension, whereas a general E-W-oriented extension prevailed further north. Analysis of reverse and strike-slip faulting in the Gariep and western Saldania Belts shows that the Pan-African constrictional deformation in South Africa was mainly controlled by ENE-WSW- to ESE-WNW-oriented shortening. Further north, the geometry of the Odgen Rock Mylonites in Namibia is controlled by N-S-striking strike-slip faults. The geometric analysis of the orientation of the mafic dykes also points to an E-W-oriented extension direction in the coastal areas extending from southern Angola to Meob and Conception Bay in west-central Namiba and changes to a generally NE-SW-oriented extension along the west coast of South Africa. Further inland in the Damara Belt sensu strictu, the geometric analysis of dykes belonging to the Hentjes Bay-Outjo Dyke Swarm also indicates NE-SW-oriented extension but, in addition, also a strong component of NW-SE-directed extension controlled dyke emplacement. The results of this study suggest that Pan-African (or older) structural discontinuities were re-utilised during the opening of the South Atlantic in the Early Cretaceous. The extension directions associated with Cretaceous Gondwana break-up structures are subparallel to the Pan-African shortening orientations. The inherited structural anisotropies are generally parallel to

  5. Optics Alignment Panel

    NASA Technical Reports Server (NTRS)

    Schroeder, Daniel J.

    1992-01-01

    The Optics Alignment Panel (OAP) was commissioned by the HST Science Working Group to determine the optimum alignment of the OTA optics. The goal was to find the position of the secondary mirror (SM) for which there is no coma or astigmatism in the camera images due to misaligned optics, either tilt or decenter. The despace position was reviewed of the SM and the optimum focus was sought. The results of these efforts are as follows: (1) the best estimate of the aligned position of the SM in the notation of HDOS is (DZ,DY,TZ,TY) = (+248 microns, +8 microns, +53 arcsec, -79 arcsec), and (2) the best focus, defined to be that despace which maximizes the fractional energy at 486 nm in a 0.1 arcsec radius of a stellar image, is 12.2 mm beyond paraxial focus. The data leading to these conclusions, and the estimated uncertainties in the final results, are presented.

  6. Multiple Sequence Alignment.

    PubMed

    Bawono, Punto; Dijkstra, Maurits; Pirovano, Walter; Feenstra, Anton; Abeln, Sanne; Heringa, Jaap

    2017-01-01

    The increasing importance of Next Generation Sequencing (NGS) techniques has highlighted the key role of multiple sequence alignment (MSA) in comparative structure and function analysis of biological sequences. MSA often leads to fundamental biological insight into sequence-structure-function relationships of nucleotide or protein sequence families. Significant advances have been achieved in this field, and many useful tools have been developed for constructing alignments, although many biological and methodological issues are still open. This chapter first provides some background information and considerations associated with MSA techniques, concentrating on the alignment of protein sequences. Then, a practical overview of currently available methods and a description of their specific advantages and limitations are given, to serve as a helpful guide or starting point for researchers who aim to construct a reliable MSA.

  7. Improved docking alignment system

    NASA Technical Reports Server (NTRS)

    Monford, Leo G. (Inventor)

    1988-01-01

    Improved techniques are provided for the alignment of two objects. The present invention is particularly suited for 3-D translation and 3-D rotational alignment of objects in outer space. A camera is affixed to one object, such as a remote manipulator arm of the spacecraft, while the planar reflective surface is affixed to the other object, such as a grapple fixture. A monitor displays in real-time images from the camera such that the monitor displays both the reflected image of the camera and visible marking on the planar reflective surface when the objects are in proper alignment. The monitor may thus be viewed by the operator and the arm manipulated so that the reflective surface is perpendicular to the optical axis of the camera, the roll of the reflective surface is at a selected angle with respect to the camera, and the camera is spaced a pre-selected distance from the reflective surface.

  8. Whole-genome alignment.

    PubMed

    Dewey, Colin N

    2012-01-01

    Whole-genome alignment (WGA) is the prediction of evolutionary relationships at the nucleotide level between two or more genomes. It combines aspects of both colinear sequence alignment and gene orthology prediction, and is typically more challenging to address than either of these tasks due to the size and complexity of whole genomes. Despite the difficulty of this problem, numerous methods have been developed for its solution because WGAs are valuable for genome-wide analyses, such as phylogenetic inference, genome annotation, and function prediction. In this chapter, we discuss the meaning and significance of WGA and present an overview of the methods that address it. We also examine the problem of evaluating whole-genome aligners and offer a set of methodological challenges that need to be tackled in order to make the most effective use of our rapidly growing databases of whole genomes.

  9. Magnetically Aligned Supramolecular Hydrogels

    PubMed Central

    Wallace, Matthew; Cardoso, Andre Zamith; Frith, William J; Iggo, Jonathan A; Adams, Dave J

    2014-01-01

    The magnetic-field-induced alignment of the fibrillar structures present in an aqueous solution of a dipeptide gelator, and the subsequent retention of this alignment upon transformation to a hydrogel upon the addition of CaCl2 or upon a reduction in solution pH is reported. Utilising the switchable nature of the magnetic field coupled with the slow diffusion of CaCl2, it is possible to precisely control the extent of anisotropy across a hydrogel, something that is generally very difficult to do using alternative methods. The approach is readily extended to other compounds that form viscous solutions at high pH. It is expected that this work will greatly expand the utility of such low-molecular-weight gelators (LMWG) in areas where alignment is key. PMID:25345918

  10. Thermonuclear breakup reactions of light nuclei. II - Gamma-ray line production and other applications

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal

    1989-01-01

    The main consequence of nuclear breakup reactions in high-temperature plasmas is shown to be to reduce the production of the gamma-ray lines, due to the breakup of these species at high temperature. Results of the emissivities of all the relevant gamma-ray lines are discussed. It is shown that the magnitude of the breakup effect on the line emissivities depends strongly on temperature, but more importantly on the plasma density and on the available time for the ion processes. Other effects considered include the production of neutrons (from the breakup of helium) and its consequences (such as the production of gamma rays from n-capture reactions and dynamical effects in accretion disk plasmas).

  11. Facing a breakup: Electromyographic responses moderate self-concept recovery following a romantic separation

    PubMed Central

    MASON, ASHLEY E.; LAW, RITA W.; BRYAN, AMANDA E. B.; PORTLEY, ROBERT M.; SBARRA, DAVID A.

    2015-01-01

    Romantic breakups arouse fundamental questions about the self: Who am I without my partner? This study examined self-concept reorganization and psychological well-being over an 8-week period in the months following a breakup. Multilevel analyses revealed that poorer self-concept recovery preceded poorer well-being and was associated with love for an ex-partner, suggesting that failure to redefine the self contributes to post-breakup distress. Psychophysiological data revealed that greater activity in the corrugator supercilia facial muscle while thinking about an ex-partner predicted poorer self-concept recovery and strengthened the negative association between love for an ex-partner and self-concept recovery. Thus, the interaction between self-report and psychophysiological data provided information about the importance of self-concept recovery to post-breakup adjustment not tapped by either method alone. PMID:26167126

  12. Trends in the Spring Breakup Dates Within the National Petroleum Reserve-Alaska

    NASA Astrophysics Data System (ADS)

    Vas, D. A.; Toniolo, H. A.

    2015-12-01

    The National Petroleum Reserve in Alaska (NPR-A) is a vast area of approximately 23 million acres and it extends from the north side of the Brooks Range to the Arctic Ocean. The Bureau of Land Management (BLM) installed seven gauging stations, starting in 2003, to establish baseline conditions for weather and hydrological variables. These stations are equipped with sensors capable of tracking water level and temperature changes in the streams, air temperature, wind speed and direction, and rain fall. This work covers the entire record of water level changes at each station during spring breakup and focuses on first flow dates, which could reflect changing weather conditions in the area. Observed trends indicate a general tendency to early breakup dates in the region. Some of the available data point out a change of nearly two weeks in the breakup date. Additionally, the tendency to early breakup seems to be accentuated in recent years.

  13. Thermonuclear breakup reactions of light nuclei. II - Gamma-ray line production and other applications

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal

    1989-01-01

    The main consequence of nuclear breakup reactions in high-temperature plasmas is shown to be to reduce the production of the gamma-ray lines, due to the breakup of these species at high temperature. Results of the emissivities of all the relevant gamma-ray lines are discussed. It is shown that the magnitude of the breakup effect on the line emissivities depends strongly on temperature, but more importantly on the plasma density and on the available time for the ion processes. Other effects considered include the production of neutrons (from the breakup of helium) and its consequences (such as the production of gamma rays from n-capture reactions and dynamical effects in accretion disk plasmas).

  14. MUSE optical alignment procedure

    NASA Astrophysics Data System (ADS)

    Laurent, Florence; Renault, Edgard; Loupias, Magali; Kosmalski, Johan; Anwand, Heiko; Bacon, Roland; Boudon, Didier; Caillier, Patrick; Daguisé, Eric; Dubois, Jean-Pierre; Dupuy, Christophe; Kelz, Andreas; Lizon, Jean-Louis; Nicklas, Harald; Parès, Laurent; Remillieux, Alban; Seifert, Walter; Valentin, Hervé; Xu, Wenli

    2012-09-01

    MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT integral field spectrograph (1x1arcmin² Field of View) developed for the European Southern Observatory (ESO), operating in the visible wavelength range (0.465-0.93 μm). A consortium of seven institutes is currently assembling and testing MUSE in the Integration Hall of the Observatoire de Lyon for the Preliminary Acceptance in Europe, scheduled for 2013. MUSE is composed of several subsystems which are under the responsibility of each institute. The Fore Optics derotates and anamorphoses the image at the focal plane. A Splitting and Relay Optics feed the 24 identical Integral Field Units (IFU), that are mounted within a large monolithic instrument mechanical structure. Each IFU incorporates an image slicer, a fully refractive spectrograph with VPH-grating and a detector system connected to a global vacuum and cryogenic system. During 2011, all MUSE subsystems were integrated, aligned and tested independently in each institute. After validations, the systems were shipped to the P.I. institute at Lyon and were assembled in the Integration Hall This paper describes the end-to-end optical alignment procedure of the MUSE instrument. The design strategy, mixing an optical alignment by manufacturing (plug and play approach) and few adjustments on key components, is presented. We depict the alignment method for identifying the optical axis using several references located in pupil and image planes. All tools required to perform the global alignment between each subsystem are described. The success of this alignment approach is demonstrated by the good results for the MUSE image quality. MUSE commissioning at the VLT (Very Large Telescope) is planned for 2013.

  15. Projectile-breakup-induced fission-fragment angular distributions in the 6Li+232Th reaction

    NASA Astrophysics Data System (ADS)

    Pal, A.; Santra, S.; Chattopadhyay, D.; Kundu, A.; Ramachandran, K.; Tripathi, R.; Roy, B. J.; Nag, T. N.; Sawant, Y.; Sarkar, D.; Nayak, B. K.; Saxena, A.; Kailas, S.

    2017-08-01

    Background: Experimental anisotropy in fission-fragment (FF) angular distribution in reactions involving weakly bound stable projectiles with actinide targets are enhanced compared to statistical saddle-point model (SSPM) predictions. Contributions from breakup- or transfer-induced fission to total fission are cited as possible reasons for such enhancement. Purpose: To identify the breakup- or transfer-induced fission channels in 6Li+232Th reaction and to investigate their effects on FF angular anisotropy. Methods: The FF angular distributions have been measured exclusively at three beam energies (28, 32, and 36 MeV) around the Coulomb barrier in coincidence with projectile breakup fragments like α , d , and p using Si strip detectors. The angular anisotropy obtained for different exclusive breakup- or transfer-induced fission channels are compared with that for total fission. SSPM and pre-equilibrium fission models have been employed to obtain theoretical FF angular anisotropy. Results: Angular anisotropy of the fission fragments produced by different transfer- or breakup-induced fission reactions have been obtained separately in the rest frame of respective recoiling nuclei. Some of these anisotropies were found to be stronger than those of the inclusive fission. Overall angular distributions of transfer or breakup fission, integrated over all possible recoil angles with weight factor proportional to differential cross section of the complementary breakup fragment emitted in coincidence in all possible directions, were obtained. It was observed that the overall FF angular anisotropy for each of these fission channels is less than or equal to the anisotropy of total fission at all the measured energies. Assuming isotropic out-of-plane correlations between the fission fragments and light-charged particles, the overall breakup- or transfer-induced fission fragment angular distributions do not explain the observed enhancement in FF anisotropy of total fission. Pre

  16. Emulation of dynamic wavefront disturbances using a deformable mirror.

    PubMed

    Conrad, Ross A; Wilcox, Williams E; Williams, Timothy H; Michael, Steven; Roth, Jeffrey M

    2009-03-02

    Boundary-layer turbulence resulting from uneven airflow around window interfaces can impact airborne laser communications (lasercom). In the focal plane, these distortions can produce fast jitter and beam break-up, posing challenges for tracking and communications. We demonstrate an experimental emulator that reproduces aircraft aero-optical distortions using a deformable mirror. This boundary-layer emulator resides in a hardware testbed that experimentally mimics air-to-space lasercom links in a controlled, laboratory environment. The boundary-layer emulator operates in the 1.55-mum band and accurately recreates aero-optical distortions at a rate of 2 kilo-frames per second.

  17. PILOT optical alignment

    NASA Astrophysics Data System (ADS)

    Longval, Y.; Mot, B.; Ade, P.; André, Y.; Aumont, J.; Baustista, L.; Bernard, J.-Ph.; Bray, N.; de Bernardis, P.; Boulade, O.; Bousquet, F.; Bouzit, M.; Buttice, V.; Caillat, A.; Charra, M.; Chaigneau, M.; Crane, B.; Crussaire, J.-P.; Douchin, F.; Doumayrou, E.; Dubois, J.-P.; Engel, C.; Etcheto, P.; Gélot, P.; Griffin, M.; Foenard, G.; Grabarnik, S.; Hargrave, P..; Hughes, A.; Laureijs, R.; Lepennec, Y.; Leriche, B.; Maestre, S.; Maffei, B.; Martignac, J.; Marty, C.; Marty, W.; Masi, S.; Mirc, F.; Misawa, R.; Montel, J.; Montier, L.; Narbonne, J.; Nicot, J.-M.; Pajot, F.; Parot, G.; Pérot, E.; Pimentao, J.; Pisano, G.; Ponthieu, N.; Ristorcelli, I.; Rodriguez, L.; Roudil, G.; Salatino, M.; Savini, G.; Simonella, O.; Saccoccio, M.; Tapie, P.; Tauber, J.; Torre, J.-P.; Tucker, C.

    2016-07-01

    PILOT is a balloon-borne astronomy experiment designed to study the polarization of dust emission in the diffuse interstellar medium in our Galaxy at wavelengths 240 μm with an angular resolution about two arcminutes. Pilot optics is composed an off-axis Gregorian type telescope and a refractive re-imager system. All optical elements, except the primary mirror, are in a cryostat cooled to 3K. We combined the optical, 3D dimensional measurement methods and thermo-elastic modeling to perform the optical alignment. The talk describes the system analysis, the alignment procedure, and finally the performances obtained during the first flight in September 2015.

  18. RHIC survey and alignment

    SciTech Connect

    Karl, F.X.; Anderson, R.R.; Goldman, M.A.; Hemmer, F.M.; Kazmark, D. Jr.; Mroczkowski, T.T.; Roecklien, J.C.

    1993-07-01

    The Relativistic Heavy Ion Collider consists of two interlaced plane rings, a pair of mirror-symmetric beam injection arcs, a spatially curved beam transfer line from the Alternating Gradient Synchrotron, and a collection of precisely positioned and aligned magnets, on appropriately positioned support stands, threaded on those arcs. RHIC geometry is defined by six beam crossing points exactly in a plane, lying precising at the vertices of a regular hexagon of specified size position and orientation of this hexagon are defined geodetically. Survey control and alignment procedures, currently in use to construct RHIC, are described.

  19. Breakup of a liquid rivulet falling over an inclined plate: Identification of a critical Weber number

    NASA Astrophysics Data System (ADS)

    Singh, Rajesh K.; Galvin, Janine E.; Whyatt, Greg A.; Sun, Xin

    2017-05-01

    We have numerically investigated the breakup of a rivulet falling over a smooth inclined plate using the volume of fluid method. Rivulet breakup is a complex phenomenon dictated by many factors, such as physical properties (viscosity and surface tension), contact angle, inertia, and plate inclination. An extensive simulation was conducted wherein these factors were systematically investigated. Regimes for a stable rivulet and an unstable rivulet that leads to breakup are examined in terms of a critical value of the Weber number (Wecr) that delineates these regimes. A higher Wecr implies that a higher flow rate is required to maintain a stable rivulet. The impact of liquid properties is characterized by the Kapitza number (Ka). Variation of Wecr with Ka shows two trends depending on the Ka value of the liquid. Liquids with lower Ka values, corresponding to high viscosities and/or low surface tensions, show linear variation and smaller value of the critical Weber number. In other words, the lower the liquid Ka value, the more stable the rivulet will tend to be with changes in liquid inertia. A liquid having higher Ka value exhibits larger value of Wecr and quadratic variation of Wecr with Ka. This behavior is more pronounced with increasing contact angle (γ). Higher contact angles promote rivulet breakup so that inertia must be higher to suppress breakup, consequently Wecr increases with increasing γ. The effect of plate inclination on breakup shows that Wecr decreases with increased inclination angle (θ) owing to higher effective liquid inertia. However, the effect is negligible beyond θ >60 ° . The effect of the inlet size reveals that Wecr decreases with inlet cross-sectional area, but the corresponding solvent flow rate for rivulet breakup remains unchanged. A phenomenological scaling for the critical Weber number with the Kapitza number and contact angle is presented, which may offer insight into rivulet breakup.

  20. A Genesis breakup and burnup analysis in off-nominal Earth return and atmospheric entry

    NASA Technical Reports Server (NTRS)

    Salama, Ahmed; Ling, Lisa; McRonald, Angus

    2005-01-01

    The Genesis project conducted a detailed breakup/burnup analysis before the Earth return to determine if any spacecraft component could survive and reach the ground intact in case of an off-nominal entry. In addition, an independent JPL team was chartered with the responsibility of analyzing several definitive breakup scenarios to verify the official project analysis. This paper presents the analysis and results of this independent team.

  1. Aerosol cluster impact and break-up : model and implementation.

    SciTech Connect

    Lechman, Jeremy B.

    2010-10-01

    In this report a model for simulating aerosol cluster impact with rigid walls is presented. The model is based on JKR adhesion theory and is implemented as an enhancement to the granular (DEM) package within the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Modeling the interactions of small particles is relevant to a number of applications (e.g., soils, powders, colloidal suspensions, etc.). Modeling the behavior of aerosol particles during agglomeration and cluster dynamics upon impact with a wall is of particular interest. In this report we describe preliminary efforts to develop and implement physical models for aerosol particle interactions. Future work will consist of deploying these models to simulate aerosol cluster behavior upon impact with a rigid wall for the purpose of developing relationships for impact speed and probability of stick/bounce/break-up as well as to assess the distribution of cluster sizes if break-up occurs. These relationships will be developed consistent with the need for inputs into system-level codes. Section 2 gives background and details on the physical model as well as implementations issues. Section 3 presents some preliminary results which lead to discussion in Section 4 of future plans.

  2. Cheating, breakup, and divorce: is Facebook use to blame?

    PubMed

    Clayton, Russell B; Nagurney, Alexander; Smith, Jessica R

    2013-10-01

    The purpose of the present study was to investigate the relationship between using the social networking site known as Facebook and negative interpersonal relationship outcomes. A survey of 205 Facebook users aged 18-82 was conducted using a 16-question online survey to examine whether high levels of Facebook use predicted negative relationship outcomes (breakup/divorce, emotional cheating, and physical cheating). It was hypothesized that those with higher levels of Facebook use would demonstrate more negative relationship outcomes than those with lower use. The study then examined whether these relationships were mediated by Facebook-related conflict. Furthermore, the researchers examined length of relationship as a moderator variable in the aforementioned model. The results indicate that a high level of Facebook usage is associated with negative relationship outcomes, and that these relationships are indeed mediated by Facebook-related conflict. This series of relationships only holds for those who are, or have been, in relatively newer relationships of 3 years or less. The current study adds to the growing body of literature investigating Internet use and relationship outcomes, and may be a precursor to further research investigating whether Facebook use attributes to the divorce rate, emotional cheating, and physical cheating.

  3. Vibration-Induced Gas-Liquid Interface Breakup

    NASA Astrophysics Data System (ADS)

    O'Hern, Timothy; Torczynski, John; Romero, Ed; Shelden, Bion

    2010-11-01

    Gas-liquid interfaces can be forced to break up when subjected to vibrations within critical ranges of frequency and amplitude. This breakup mechanism was examined experimentally using deep layers of silicone oils over a range of viscosity and sinusoidal, primarily axial vibration conditions that can produce dramatic disturbances at the gas-liquid free surface. Although small-amplitude vibrations produce standing Faraday waves, large-amplitude vibrations produce liquid jets into the gas, droplets pinching off from the jets, gas cavities in the liquid from droplet impact, and bubble transport below the interface. Experiments used several different silicone oils over a range of pressures and vibration conditions. Computational simulations exhibiting similar behavior will be included in the presentation. Applications include liquid fuel rockets, inertial sensing devices, moving vehicles, mixing processes, and acoustic excitation. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Drag reduction - Jet breakup correlation with kerosene-based additives

    NASA Technical Reports Server (NTRS)

    Hoyt, J. W.; Altman, R. L.; Taylor, J. J.

    1980-01-01

    The drag-reduction effectiveness of a number of high-polymer additives dissolved in aircraft fuel has been measured in a turbulent-flow rheometer. These solutions were further subjected to high elongational stress and breakup forces in a jet discharging in air. The jet was photographed using a high-resolution camera with special lighting. The object of the work was to study the possible spray-suppression ability of high-polymer additives to aircraft fuel and to correlate this with the drag-reducing properties of the additives. It was found, in fact, that the rheometer results indicate the most effective spray-suppressing additives. Using as a measure the minimum polymer concentration to give a maximum friction-reducing effect, the order of effectiveness of eight different polymer additives as spray-suppressing agents was predicted. These results may find application in the development of antimisting additives for aircraft fuel which may increase fire safety in case of crash or accident.

  5. Decrease in oceanic crustal thickness since the breakup of Pangaea

    NASA Astrophysics Data System (ADS)

    van Avendonk, Harm J. A.; Davis, Joshua K.; Harding, Jennifer L.; Lawver, Lawrence A.

    2017-01-01

    Earth's mantle has cooled by 6-11 °C every 100 million years since the Archaean, 2.5 billion years ago. In more recent times, the surface heat loss that led to this temperature drop may have been enhanced by plate-tectonic processes, such as continental breakup, the continuous creation of oceanic lithosphere at mid-ocean ridges and subduction at deep-sea trenches. Here we use a compilation of marine seismic refraction data from ocean basins globally to analyse changes in the thickness of oceanic crust over time. We find that oceanic crust formed in the mid-Jurassic, about 170 million years ago, is 1.7 km thicker on average than crust produced along the present-day mid-ocean ridge system. If a higher mantle temperature is the cause of thicker Jurassic ocean crust, the upper mantle may have cooled by 15-20 °C per 100 million years over this time period. The difference between this and the long-term mantle cooling rate indeed suggests that modern plate tectonics coincide with greater mantle heat loss. We also find that the increase of ocean crustal thickness with plate age is stronger in the Indian and Atlantic oceans compared with the Pacific Ocean. This observation supports the idea that upper mantle temperature in the Jurassic was higher in the wake of the fragmented supercontinent Pangaea due to the effect of continental insulation.

  6. On tear film breakup (TBU): dynamics and imaging.

    PubMed

    Braun, Richard J; Driscoll, Tobin A; Begley, Carolyn G; King-Smith, P Ewen; Siddique, Javed I

    2017-02-20

    We report the results of some recent experiments to visualize tear film dynamics. We then study a mathematical model for tear film thinning and tear film breakup (TBU), a term from the ocular surface literature. The thinning is driven by an imposed tear film thinning rate which is input from in vivo measurements. Solutes representing osmolarity and fluorescein are included in the model. Osmolarity causes osmosis from the model ocular surface, and the fluorescein is used to compute the intensity corresponding closely to in vivo observations. The imposed thinning can be either one-dimensional or axisymmetric, leading to streaks or spots of TBU, respectively. For a spatially-uniform (flat) film, osmosis would cease thinning and balance mass lost due to evaporation; for these space-dependent evaporation profiles TBU does occur because osmolarity diffuses out of the TBU into the surrounding tear film, in agreement with previous results. The intensity pattern predicted based on the fluorescein concentration is compared with the computed thickness profiles; this comparison is important for interpreting in vivo observations. The non-dimensionalization introduced leads to insight about the relative importance of the competing processes; it leads to a classification of large vs small TBU regions in which different physical effects are dominant. Many regions of TBU may be considered small, revealing that the flow inside the film has an appreciable influence on fluorescence imaging of the tear film.

  7. Breakup of evaporating/burning slurry drops by additives

    NASA Astrophysics Data System (ADS)

    Choudhury, P. Roy; Gerstein, M.

    Single drops of silicon carbide-cumene slurry were suspended from a quartz fiber and ignited. An inert material such as silicon carbide was chosen so that the droplets can be burned until all the fuel is consumed and only the inert residue is left on the quartz fiber. Benzoyl peroxide was added to cumene and the time to disruption of the liquid drop was measured. In the case of benzoyl peroxide, the breaking up of the drop resulting from its thermal decomposition produced CO 2. Both the drop disruption time and the burning of the slurry to dryness were predicted theoretically. Radiation absorption was found to be an important factor in the case of the slurry. Benzoyl peroxide and carbamide peroxide were investigated as additives to a boron slurry to determine if effective drop break-up could be achieved. Both additives produced drop shattering. The carbamide peroxide was particularly effective due to the production of O 2. The green flame associated with boron burning was clearly evident.

  8. Asteroid breakup linked to the Great Ordovician Biodiversification Event

    NASA Astrophysics Data System (ADS)

    Schmitz, Birger; Harper, David A. T.; Peucker-Ehrenbrink, Bernhard; Stouge, Svend; Alwmark, Carl; Cronholm, Anders; Bergström, Stig M.; Tassinari, Mario; Xiaofeng, Wang

    2008-01-01

    The rise and diversification of shelled invertebrate life in the early Phanerozoic eon occurred in two major stages. During the first stage (termed as the Cambrian explosion), a large number of new phyla appeared over a short time interval ~540Myrago. Biodiversity at the family, genus and species level, however, remained low until the second stage marked by the Great Ordovician Biodiversification Event in the Middle Ordovician period. Although this event represents the most intense phase of species radiation during the Palaeozoic era and led to irreversible changes in the biological make-up of Earth's seafloors, the causes of this event remain elusive. Here, we show that the onset of the major phase of biodiversification ~470Myrago coincides with the disruption in the asteroid belt of the L-chondrite parent body-the largest documented asteroid breakup event during the past few billion years. The precise coincidence between these two events is established by bed-by-bed records of extraterrestrial chromite, osmium isotopes and invertebrate fossils in Middle Ordovician strata in Baltoscandia and China. We argue that frequent impacts on Earth of kilometre-sized asteroids-supported by abundant Middle Ordovician fossil meteorites and impact craters-accelerated the biodiversification process.

  9. Analytical description of the breakup of liquid jets in air

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.

    1993-01-01

    A viscous or inviscid cylindrical jet with surface tension in a vacuum tends to pinch due to the mechanism of capillary instability. Similarity solutions are constructed which describe this phenomenon as a critical time is encountered, for two physically distinct cases: inviscid jets governed by the Euler equations and highly viscous jets governed by the Stokes equations. In both cases the only assumption imposed is that at the time of pinching the jet shape has a radial length scale which is smaller than the axial length scale. For the inviscid case, we show that our solution corresponds exactly to one member of the one-parameter family of solutions obtained from slender jet theories and the shape of the jet is locally concave at breakup. For highly viscous jets our theory predicts local shapes which are monotonic increasing or decreasing indicating the formation of a mother drop connected to the jet by a thin fluid tube. This qualitative behavior is in complete agreement with both direct numerical simulations and experimental observations.

  10. Beam break-up estimates for the ERL at BNL

    SciTech Connect

    Ben-Zvi, I.; Calaga, R.; Hahn, H.; Hammons, L.; Johnson, E.; Kayran, D.; Litvinenko, V.; Kewisch, J.; Xu, W.

    2010-05-23

    A prototype Ampere-class superconducting energy recovery linac (ERL) is under advanced construction at BNL. The ERL facility is comprised of a five-cell SC Linac plus a half-cell SC photo-injector RF electron gun, both operating at 703.75 MHz. The facility is designed for either a high-current mode of operation up to 0.5 A at 703.75 MHz or a high-bunch-charge mode of 5 nC at 10 MHz bunch frequency. The R&D facility serves a test bed for an envisioned electron-hadron collider, eRHIC. The high-current, high-charge operating parameters make effective higher-order-mode (HOM) damping mandatory, and requires the determination of HOM tolerances for a cavity upgrade. The niobium cavity has been tested at superconducting temperatures and has provided measured quality factors (Q) for a large number of modes. These numbers were used for the estimate of the beam breakup instability (BBU). The facility will be assembled with a highly flexible lattice covering a vast operational parameter space for verification of the estimates and to serve as a test bed for the concepts directed at future projects.

  11. Initial diversification of living amphibians predated the breakup of Pangaea.

    PubMed

    San Mauro, Diego; Vences, Miguel; Alcobendas, Marina; Zardoya, Rafael; Meyer, Axel

    2005-05-01

    The origin and divergence of the three living orders of amphibians (Anura, Caudata, Gymnophiona) and their main lineages are one of the most hotly debated topics in vertebrate evolution. Here, we present a robust molecular phylogeny based on the nuclear RAG1 gene as well as results from a variety of alternative independent molecular clock calibrations. Our analyses suggest that the origin and early divergence of the three living amphibian orders dates back to the Palaeozoic or early Mesozoic, before the breakup of Pangaea, and soon after the divergence from lobe-finned fishes. The resulting new biogeographic scenario, age estimate, and the inferred rapid divergence of the three lissamphibian orders may account for the lack of fossils that represent plausible ancestors or immediate sister taxa of all three orders and the heretofore paradoxical distribution of some amphibian fossil taxa. Furthermore, the ancient and rapid radiation of the three lissamphibian orders likely explains why branch lengths connecting their early nodes are particularly short, thus rendering phylogenetic inference of implicated relationships especially difficult.

  12. Drag reduction - Jet breakup correlation with kerosene-based additives

    NASA Technical Reports Server (NTRS)

    Hoyt, J. W.; Altman, R. L.; Taylor, J. J.

    1980-01-01

    The drag-reduction effectiveness of a number of high-polymer additives dissolved in aircraft fuel has been measured in a turbulent-flow rheometer. These solutions were further subjected to high elongational stress and breakup forces in a jet discharging in air. The jet was photographed using a high-resolution camera with special lighting. The object of the work was to study the possible spray-suppression ability of high-polymer additives to aircraft fuel and to correlate this with the drag-reducing properties of the additives. It was found, in fact, that the rheometer results indicate the most effective spray-suppressing additives. Using as a measure the minimum polymer concentration to give a maximum friction-reducing effect, the order of effectiveness of eight different polymer additives as spray-suppressing agents was predicted. These results may find application in the development of antimisting additives for aircraft fuel which may increase fire safety in case of crash or accident.

  13. Style of rifting and the stages of Pangea breakup

    NASA Astrophysics Data System (ADS)

    Frizon de Lamotte, Dominique; Fourdan, Brendan; Leleu, Sophie; Leparmentier, François; de Clarens, Philippe

    2015-05-01

    Pangea results from the progressive amalgamation of continental blocks achieved at 320 Ma. Assuming that the ancient concept of "active" versus "passive" rifting remains pertinent as end-members of more complex processes, we show that the progressive Pangea breakup occurred through a succession of rifting episodes characterized by different tectonic evolutions. A first episode of passive continental rifting during the Upper Carboniferous and Permian led to the formation of the Neo-Tethys Ocean. Then at the beginning of Triassic times, two short episodes of active rifting associated to the Siberian and Emeishan large igneous provinces (LIPs) failed. The true disintegration of Pangea resulted from (1) a Triassic passive rifting leading to the emplacement of the central Atlantic magmatic province (200 Ma) LIP and the subsequent opening of the central Atlantic Ocean during the lowermost Jurassic and from (2) a Lower Jurassic active rifting triggered by the Karoo-Ferrar LIP (183 Ma), which led to the opening of the West Indian Ocean. The same sequence of passive then active rifting is observed during the Lower Cretaceous with, in between, the Parana-Etendeka LIP at 135 Ma. We show that the relationships between the style of rifts and their breakdown or with the type of resulting margins (as magma poor or magma dominated) are not straightforward. Finally, we discuss the respective role of mantle global warming promoted by continental agglomeration and mantle plumes in the weakening of the continental lithosphere and their roles as rifting triggers.

  14. Numerical study of three-dimensional liquid jet breakup with adaptive unstructured meshes

    NASA Astrophysics Data System (ADS)

    Xie, Zhihua; Pavlidis, Dimitrios; Salinas, Pablo; Pain, Christopher; Matar, Omar

    2016-11-01

    Liquid jet breakup is an important fundamental multiphase flow, often found in many industrial engineering applications. The breakup process is very complex, involving jets, liquid films, ligaments, and small droplets, featuring tremendous complexity in interfacial topology and a large range of spatial scales. The objective of this study is to investigate the fluid dynamics of three-dimensional liquid jet breakup problems, such as liquid jet primary breakup and gas-sheared liquid jet breakup. An adaptive unstructured mesh modelling framework is employed here, which can modify and adapt unstructured meshes to optimally represent the underlying physics of multiphase problems and reduce computational effort without sacrificing accuracy. The numerical framework consists of a mixed control volume and finite element formulation, a 'volume of fluid' type method for the interface capturing based on a compressive control volume advection method and second-order finite element methods, and a force-balanced algorithm for the surface tension implementation. Numerical examples of some benchmark tests and the dynamics of liquid jet breakup with and without ambient gas are presented to demonstrate the capability of this method.

  15. The importance of momentum transfer in collision-induced breakups in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Reynolds, Robert C.; Lillie, Brian J.

    1991-01-01

    Although there is adequate information on larger objects in low Earth orbit, specifically those objects larger than about 10 cm in diameter, there is little direct information on objects from this size down to 1 mm. Yet, this is the sized regime where objects acting as projectiles represent the ability to seriously damage or destroy a functioning spacecraft if they collide with it. The observed consequences of known collisional breakups in orbit indicates no significant momentum transfer in the resulting debris cloud. The position taken in this paper is that this is an observational selection effect: what is seen in these events is an explosion-like breakup of the target structure arising from shock waves introduced into the structure by the collision, but one that occurs significantly after the collision processes are completed; the collision cloud, in which there is momentum transfer, consists of small, unobserved fragments. Preliminary computations of the contribution of one known collisional breakup, Solwind at 500 km in 1985, and Cosmos 1275 in 1981, assume no momentum transfer on breakup and indicate that these two events are the dominant contributors to the current millimeter and centimeter population. A different story would emerge if momentum transfer was taken into account. The topics covered include: (1) observation of on-orbit collisional breakups; (2) a model for momentum transfer; and (3) velocity space representation of breakup clouds.

  16. Experimental investigation of the breakup of a round liquid jet in a shock-induced crossflow

    NASA Astrophysics Data System (ADS)

    Olles, Joseph; Guildenbecher, Daniel; Wagner, Justin; Demauro, Edward; Farias, Paul; Grasser, Thomas; Sojka, Paul

    2015-11-01

    The breakup of a round water jet due to a step change in the convective air velocity following a 1D air-shock was experimentally investigated. Variations of this experiment have been conducted in the past, however here quantitative results on the breakup sizes and trajectories are shown. A shock tube was utilized to create the jet breakup, and the primary shape of the liquid and secondary droplet sizes were recorded optically. Through the use of digital in-line holography (DIH), the sizes, 3D position, and 3C velocities of secondary droplets were measured at kHz rates. Care was taken to ensure that the jet was kept round throughout the shock tube test section (absent of Plateau-Rayleigh instability). While the liquid jet geometry and velocity was kept constant, various gas-phase velocities allowed for the investigation of multiple breakup morphologies, as a function of the crossflow Weber number. The typical breakup regimes are seen; bag, multimode, and sheet-thinning. With high temporal and spatial resolution, interfacial and liquid column instabilities are seen in the jet breakup.

  17. Curriculum Alignment: Establishing Coherence

    ERIC Educational Resources Information Center

    Gagné, Philippe; Dumont, Laurence; Brunet, Sabine; Boucher, Geneviève

    2013-01-01

    In this paper, we present a step-by-step guide to implement a curricular alignment project, directed at professional development and student support, and developed in a higher education French as a second language department. We outline best practices and preliminary results from our experience and provide ways to adapt our experience to other…

  18. Aligned-or Not?

    ERIC Educational Resources Information Center

    Roseman, Jo Ellen; Koppal, Mary

    2015-01-01

    When state leaders and national partners in the development of the Next Generation Science Standards met to consider implementation strategies, states and school districts wanted to know which materials were aligned to the new standards. The answer from the developers was short but not sweet: You won't find much now, and it's going to…

  19. Aligning brains and minds

    PubMed Central

    Tong, Frank

    2012-01-01

    In this issue of Neuron, Haxby and colleagues describe a new method for aligning functional brain activity patterns across participants. Their study demonstrates that objects are similarly represented across different brains, allowing for reliable classification of one person’s brain activity based on another’s. PMID:22017984

  20. Optically Aligned Drill Press

    NASA Technical Reports Server (NTRS)

    Adderholdt, Bruce M.

    1994-01-01

    Precise drill press equipped with rotary-indexing microscope. Microscope and drill exchange places when turret rotated. Microscope axis first aligned over future hole, then rotated out of way so drill axis assumes its precise position. New procedure takes less time to locate drilling positions and produces more accurate results. Apparatus adapted to such other machine tools as milling and measuring machines.

  1. Precision Antenna Alignment Procedure.

    DTIC Science & Technology

    Precise azimuthal alignment of troposcatter system antennas is achieved by centering on the great circle, the combined pattern of intercepting beams...from two troposcatter antennas. The combined antenna pattern is determined to be centered on and symmetric about the great circle when the Doppler

  2. Optically Aligned Drill Press

    NASA Technical Reports Server (NTRS)

    Adderholdt, Bruce M.

    1994-01-01

    Precise drill press equipped with rotary-indexing microscope. Microscope and drill exchange places when turret rotated. Microscope axis first aligned over future hole, then rotated out of way so drill axis assumes its precise position. New procedure takes less time to locate drilling positions and produces more accurate results. Apparatus adapted to such other machine tools as milling and measuring machines.

  3. Aligned-or Not?

    ERIC Educational Resources Information Center

    Roseman, Jo Ellen; Koppal, Mary

    2015-01-01

    When state leaders and national partners in the development of the Next Generation Science Standards met to consider implementation strategies, states and school districts wanted to know which materials were aligned to the new standards. The answer from the developers was short but not sweet: You won't find much now, and it's going to…

  4. Sagittal spinal pelvic alignment.

    PubMed

    Klineberg, Eric; Schwab, Frank; Smith, Justin S; Gupta, Munish C; Lafage, Virginie; Bess, Shay

    2013-04-01

    The goal of any ambulatory patient is to maintain a horizontal gaze with the least amount of energy expenditure. With progressive deformity, and in particular sagittal malalignment, significant compensatory mechanisms must be used to achieve this goal. Each pelvis dictates the amount of lumbar lordosis required through its morphometric parameter pelvic incidence. The pelvis may compensate for decreasing lumbar lordosis (eg, age, flat back deformity) by retroverting and increasing pelvic tilt and decreasing the sacral slope. Underappreciation for these spinopelvic compensatory mechanisms leads to surgical under-correction, iatrogenic flat back and poor clinical outcomes. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Reconfigurable Photonic Capsules Containing Cholesteric Liquid Crystals with Planar Alignment.

    PubMed

    Lee, Sang Seok; Kim, Su Kyung; Won, Jong Chan; Kim, Yun Ho; Kim, Shin-Hyun

    2015-12-07

    Cholesteric liquid crystals (CLCs) reflect selected wavelengths of light owing to their periodic helical structures. The encapsulation of CLCs leads to photonic devices that can be easily processed and might be used as stand-alone microsensors. However, when CLCs are enclosed by polymeric membranes, they usually lose their planar alignment, leading to a deterioration of the optical performance. A microfluidics approach was employed to integrate an ultrathin alignment layer into microcapsules to separate the CLC core and the elastomeric solid membrane using triple-emulsion drops as the templates. The thinness of the alignment layer provides high lubrication resistance, preserving the layer integrity during elastic deformation of the membrane. The CLCs in the microcapsules can thus maintain their planar alignment, rendering the shape and optical properties highly reconfigurable. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method

    SciTech Connect

    Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

    2011-04-01

    A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 {micro}m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

  7. Variability in static alignment and kinematics for kinematically aligned TKA.

    PubMed

    Theodore, Willy; Twiggs, Joshua; Kolos, Elizabeth; Roe, Justin; Fritsch, Brett; Dickison, David; Liu, David; Salmon, Lucy; Miles, Brad; Howell, Stephen

    2017-08-01

    Total knee arthroplasty (TKA) significantly improves pain and restores a considerable degree of function. However, improvements are needed to increase patient satisfaction and restore kinematics to allow more physically demanding activities that active patients consider important. The aim of our study was to compare the alignment and motion of kinematically and mechanically aligned TKAs. A patient specific musculoskeletal computer simulation was used to compare the tibio-femoral and patello-femoral kinematics between mechanically aligned and kinematically aligned TKA in 20 patients. When kinematically aligned, femoral components on average resulted in more valgus alignment to the mechanical axis and internally rotated to surgical transepicondylar axis whereas tibia component on average resulted in more varus alignment to the mechanical axis and internally rotated to tibial AP rotational axis. With kinematic alignment, tibio-femoral motion displayed greater tibial external rotation and lateral femoral flexion facet centre (FFC) translation with knee flexion than mechanical aligned TKA. At the patellofemoral joint, patella lateral shift of kinematically aligned TKA plateaued after 20 to 30° flexion while in mechanically aligned TKA it decreased continuously through the whole range of motion. Kinematic alignment resulted in greater variation than mechanical alignment for all tibio-femoral and patello-femoral motion. Kinematic alignment places TKA components patient specific alignment which depends on the preoperative state of the knee resulting in greater variation in kinematics. The use of computational models has the potential to predict which alignment based on native alignment, kinematic or mechanical, could improve knee function for patient's undergoing TKA. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Is collisional breakup an important process within mixed-phase deep convective clouds?

    NASA Astrophysics Data System (ADS)

    Seifert, A.; Khain, A.; Mayer, F.

    2003-04-01

    The microphysics of deep convective clouds determines their precipitation efficiency as well as the dynamical evolution of cloud systems and is therefore of great importance for numerical weather prediction, flood forecasting and regional climate modeling. Of all cloud systems mixed-phase deep convection is maybe the most complex and least understood. One reason is that the numerous microphysical processes taking place are highly nonlinear and strongly coupled with each other as well as with the hydrodynamics of the cloud. Collisional breakup of raindrops is one of these cloud microphysical processes, but is often neglected or not well represented in state-of-the-art cloud resolving models. The importance of collisional breakup is well known for tropical cloud systems, which are dominated by warm phase processes. In addition various studies using so-called rainshaft models showed that collisional breakup can alter the raindrop size distribution below cloud base. But what happens within the clouds and especially within strong convective updrafts? Can collisional breakup lead to a different cloud evolution by changing the drop size distribution? Using the Hebrew University Cloud Model (HUCM), which includes the most detailed spectral microphysics model available today, we performed a sensitivity study to answer these questions. Collisional breakup was therefore recently included in HUCM using Bleck's numerical method, which is standard for simulation of the breakup process. Our breakup scheme itself is mainly based on the parameterization of Low and List (1982, JAS), but includes also additional data for small raindrops by Beard and Ochs (1995, JAS). As a test case a deep convective mixed-phase cloud is simulated with initial conditions based on a sounding from 13 August 1999, Midland/Texas. We present a detailed analysis of the simulated cloud evolution with and without collisional breakup taken into account. The conclusion from our sensitivity study is that

  9. Break-up of Pangaea and Tectonic History of the Adria Microplate

    NASA Astrophysics Data System (ADS)

    Schettino, A.; Turco, E.

    2008-12-01

    .4) describe the process of formation of an independent Iberian plate and the opening of the Valais oceanic seaway. The sixth phase, from chron M0 (120.4) to the Albian-Cenomanian boundary ("î100 Ma), is associated with the early Alpine collision. During the seventh phase, from the Albian-Cenomanian boundary ("î100 Ma) to chron C34ny (83.5 Ma), a relatively large block comprising Adria, Greece, and Turkey separated from Africa, determining a new spreading event in the eastern Mediterranean and further East in the Tethys. The next four phases, from chron C34ny (83.5 Ma) to chron C13 (33.1 Ma), describe the Pyrenean and Alpine collisions, the subduction of the Ligurian and Valais oceans, the progressive internal deformation of Adria, and the assembly of the modern Anatolian block. In phase 12, from chron C13 (33.1 Ma) to chron C6n (19 Ma), are included the formation of the Atlas mountain belt and the onset of rifting and sea-floor spreading in the western Mediterranean. During this time interval Morocco was an independent plate with a distinct spreading rate with respect to North America. Finally, during the last phase passive subduction of the last remains of southern Liguride, Ionian, and Pennine oceans determined the opening of the Alboran, Tyrrhenian, and Pannonian basins, accompanied by trench retreat. Thirteen plate tectonic reconstructions and a computer animation are proposed to illustrate the major phases of plate motions in the western Tethys region during and after the breakup of the Pangaea supercontinent.

  10. Continental breakup and its effect on MORB chemistry

    NASA Astrophysics Data System (ADS)

    Brandl, P. A.; Regelous, M.; Beier, C.; Haase, K. M.

    2012-12-01

    The formation and breakup of supercontinents has major influences on the climate, sealevel and the biosphere on a global scale. The question of possible effects of a supercontinent on mantle convection and thus spreading in the ocean basins has been recently addressed by various studies, focused on numerical modelling. These studies predict higher mantle temperatures on the order of 100°C higher due to the effect of 'continental insulation'. This temperature difference would amplify the effects on sealevel and volcanic CO2 output associated with creation of new spreading centres. However, there is as yet no direct geochemical evidence that could confirm or quantify the continental insulation effect. We have sampled 340 fresh glasses from 30 different sites drilled into old oceanic crust (6-170 Ma) and determined their chemical composition using electron microprobe and ICP-MS techniques. The oldest MORB recovered from the Atlantic and Indian Oceans have lower Na72, higher Fe72 than zero-age MORB. If interpreted as the effects of mantle potential temperature, this chemical difference indicates a mantle source hotter by 50-150°C depending on primary melt composition and applied geothermometry. Higher mantle potential temperatures during the Mesozoic are not a global phenomena but instead restricted to the proto-Atlantic and Indian Ocean. Zero-age MORB from the juvenile Red Sea - Gulf of Aden have similar major element compositions, indicating that higher mantle temperatures beneath young ocean basins result from continental insulation. A subset of about 120 samples has been also analysed for trace element composition using laser ablation and solution ICPMS techniques. These samples are representative for our ancient MORB database in terms of age and geological setting. Trace element ratios sensitive to the degree of partial melting or source fertility such as La/Sm, Sm/Yb, La/Yb or (Dy/Yb)N are positively correlated with fractionation corrected Na2O and negatively

  11. Flexible structural protein alignment by a sequence of local transformations

    PubMed Central

    Rocha, Jairo; Segura, Joan; Wilson, Richard C.; Dasgupta, Swagata

    2009-01-01

    Motivation: Throughout evolution, homologous proteins have common regions that stay semi-rigid relative to each other and other parts that vary in a more noticeable way. In order to compare the increasing number of structures in the PDB, flexible geometrical alignments are needed, that are reliable and easy to use. Results: We present a protein structure alignment method whose main feature is the ability to consider different rigid transformations at different sites, allowing for deformations beyond a global rigid transformation. The performance of the method is comparable with that of the best ones from 10 aligners tested, regarding both the quality of the alignments with respect to hand curated ones, and the classification ability. An analysis of some structure pairs from the literature that need to be matched in a flexible fashion are shown. The use of a series of local transformations can be exported to other classifiers, and a future golden protein similarity measure could benefit from it. Availability: A public server for the program is available at http://dmi.uib.es/ProtDeform/. Contact: jairo@uib.es Supplementary information: All data used, results and examples are available at http://dmi.uib.es/people/jairo/bio/ProtDeform.Supplementary data are available at Bioinformatics online. PMID:19417057

  12. Subducting Plate Breakup by Plume-Lithosphere Interaction

    NASA Astrophysics Data System (ADS)

    Koptev, A.; Gerya, T.; Jolivet, L.; Leroy, S. D.

    2016-12-01

    We use a 3D high-resolution thermo-mechanical modeling to investigate the impact of active mantle plume on a subducting lithospheric plate. Initial model setup consists of an overriding continental lithosphere and subducting lithospheric plate including oceanic and continental lithosphere. A mantle plume thermal anomaly has been initially seeded at the bottom of the model box underneath the continental segment of subducting plate. Mantle plume impingement on lithospheric bottom leads to thinning of continental lithosphere and decompressional melting of both lithospheric and sublithospheric mantle along stretched trench-parallel zone. Further continental breakup is followed by opening of an oceanic basin separating a newly formed microcontinent from the main subducting continent. Despite continuous push applied at the boundary of subducting plate, plume-induced oceanic basin opens during several Myrs reaching several hundred kilometers wide. Cooling of the mantle plume and beginning of collision between the separated microcontinent and the overriding continental plate lead to gradual closure of newly formed oceanic basin that gets further involved into subduction and collision. The final stage sees continental subduction of main body of subducting plate and simultaneous tectonic exhumation of the upper crust of the subducted microcontinent. This scenario involving a plume-induced rifting of a microcontinent away from main body of subducted plate can be compared to the Mesozoic-Cenozoic development of the African plate characterized by the consecutive separation of the Apulian microcontinent and Arabian plate (in the Jurassic and the Neogene, respectively) during subduction of Neo-Tethys oceanic lithosphere beneath the Eurasian margin.

  13. Possible Effects of Collisional Breakup on Mixed-Phase Deep Convection Simulated by a Spectral (Bin) Cloud Model.

    NASA Astrophysics Data System (ADS)

    Seifert, Axel; Khain, Alexander; Blahak, Ulrich; Beheng, Klaus D.

    2005-06-01

    The effects of the collisional breakup of raindrops are investigated using the Hebrew University Cloud Model (HUCM). The parameterizations, which are combined in the new breakup scheme, are those of Low and List, Beard and Ochs, as well as Brown. A sensitivity study reveals strong effects of collisional breakup on the precipitation formation in mixed-phase deep convective clouds for strong as well as for weak precipitation events. Collisional breakup reduces the number of large raindrops, increases the number of small raindrops, and, as a consequence, decreases surface rain rates and considerably reduces the speed of rain formation. In addition, it was found that including breakup can lead to a more intense triggering of secondary convective cells. But a statistical comparison with observed raindrop size distributions shows that the parameterizations might systematically overestimate collisional breakup.

  14. Kernel Manifold Alignment for Domain Adaptation

    PubMed Central

    Tuia, Devis; Camps-Valls, Gustau

    2016-01-01

    The wealth of sensory data coming from different modalities has opened numerous opportunities for data analysis. The data are of increasing volume, complexity and dimensionality, thus calling for new methodological innovations towards multimodal data processing. However, multimodal architectures must rely on models able to adapt to changes in the data distribution. Differences in the density functions can be due to changes in acquisition conditions (pose, illumination), sensors characteristics (number of channels, resolution) or different views (e.g. street level vs. aerial views of a same building). We call these different acquisition modes domains, and refer to the adaptation problem as domain adaptation. In this paper, instead of adapting the trained models themselves, we alternatively focus on finding mappings of the data sources into a common, semantically meaningful, representation domain. This field of manifold alignment extends traditional techniques in statistics such as canonical correlation analysis (CCA) to deal with nonlinear adaptation and possibly non-corresponding data pairs between the domains. We introduce a kernel method for manifold alignment (KEMA) that can match an arbitrary number of data sources without needing corresponding pairs, just few labeled examples in all domains. KEMA has interesting properties: 1) it generalizes other manifold alignment methods, 2) it can align manifolds of very different complexities, performing a discriminative alignment preserving each manifold inner structure, 3) it can define a domain-specific metric to cope with multimodal specificities, 4) it can align data spaces of different dimensionality, 5) it is robust to strong nonlinear feature deformations, and 6) it is closed-form invertible, which allows transfer across-domains and data synthesis. To authors’ knowledge this is the first method addressing all these important issues at once. We also present a reduced-rank version of KEMA for computational

  15. Kernel Manifold Alignment for Domain Adaptation.

    PubMed

    Tuia, Devis; Camps-Valls, Gustau

    2016-01-01

    The wealth of sensory data coming from different modalities has opened numerous opportunities for data analysis. The data are of increasing volume, complexity and dimensionality, thus calling for new methodological innovations towards multimodal data processing. However, multimodal architectures must rely on models able to adapt to changes in the data distribution. Differences in the density functions can be due to changes in acquisition conditions (pose, illumination), sensors characteristics (number of channels, resolution) or different views (e.g. street level vs. aerial views of a same building). We call these different acquisition modes domains, and refer to the adaptation problem as domain adaptation. In this paper, instead of adapting the trained models themselves, we alternatively focus on finding mappings of the data sources into a common, semantically meaningful, representation domain. This field of manifold alignment extends traditional techniques in statistics such as canonical correlation analysis (CCA) to deal with nonlinear adaptation and possibly non-corresponding data pairs between the domains. We introduce a kernel method for manifold alignment (KEMA) that can match an arbitrary number of data sources without needing corresponding pairs, just few labeled examples in all domains. KEMA has interesting properties: 1) it generalizes other manifold alignment methods, 2) it can align manifolds of very different complexities, performing a discriminative alignment preserving each manifold inner structure, 3) it can define a domain-specific metric to cope with multimodal specificities, 4) it can align data spaces of different dimensionality, 5) it is robust to strong nonlinear feature deformations, and 6) it is closed-form invertible, which allows transfer across-domains and data synthesis. To authors' knowledge this is the first method addressing all these important issues at once. We also present a reduced-rank version of KEMA for computational

  16. Inflation by alignment

    SciTech Connect

    Burgess, C.P.; Roest, Diederik

    2015-06-08

    Pseudo-Goldstone bosons (pGBs) can provide technically natural inflatons, as has been comparatively well-explored in the simplest axion examples. Although inflationary success requires trans-Planckian decay constants, f≳M{sub p}, several mechanisms have been proposed to obtain this, relying on (mis-)alignments between potential and kinetic energies in multiple-field models. We extend these mechanisms to a broader class of inflationary models, including in particular the exponential potentials that arise for pGB potentials based on noncompact groups (and so which might apply to moduli in an extra-dimensional setting). The resulting potentials provide natural large-field inflationary models and can predict a larger primordial tensor signal than is true for simpler single-field versions of these models. In so doing we provide a unified treatment of several alignment mechanisms, showing how each emerges as a limit of the more general setup.

  17. Alignment reference device

    DOEpatents

    Patton, Gail Y.; Torgerson, Darrel D.

    1987-01-01

    An alignment reference device provides a collimated laser beam that minimizes angular deviations therein. A laser beam source outputs the beam into a single mode optical fiber. The output end of the optical fiber acts as a source of radiant energy and is positioned at the focal point of a lens system where the focal point is positioned within the lens. The output beam reflects off a mirror back to the lens that produces a collimated beam.

  18. Nuclear reactor alignment plate configuration

    SciTech Connect

    Altman, David A; Forsyth, David R; Smith, Richard E; Singleton, Norman R

    2014-01-28

    An alignment plate that is attached to a core barrel of a pressurized water reactor and fits within slots within a top plate of a lower core shroud and upper core plate to maintain lateral alignment of the reactor internals. The alignment plate is connected to the core barrel through two vertically-spaced dowel pins that extend from the outside surface of the core barrel through a reinforcement pad and into corresponding holes in the alignment plate. Additionally, threaded fasteners are inserted around the perimeter of the reinforcement pad and into the alignment plate to further secure the alignment plate to the core barrel. A fillet weld also is deposited around the perimeter of the reinforcement pad. To accomodate thermal growth between the alignment plate and the core barrel, a gap is left above, below and at both sides of one of the dowel pins in the alignment plate holes through with the dowel pins pass.

  19. Orbit IMU alignment: Error analysis

    NASA Technical Reports Server (NTRS)

    Corson, R. W.

    1980-01-01

    A comprehensive accuracy analysis of orbit inertial measurement unit (IMU) alignments using the shuttle star trackers was completed and the results are presented. Monte Carlo techniques were used in a computer simulation of the IMU alignment hardware and software systems to: (1) determine the expected Space Transportation System 1 Flight (STS-1) manual mode IMU alignment accuracy; (2) investigate the accuracy of alignments in later shuttle flights when the automatic mode of star acquisition may be used; and (3) verify that an analytical model previously used for estimating the alignment error is a valid model. The analysis results do not differ significantly from expectations. The standard deviation in the IMU alignment error for STS-1 alignments was determined to the 68 arc seconds per axis. This corresponds to a 99.7% probability that the magnitude of the total alignment error is less than 258 arc seconds.

  20. Deformation and burst of a liquid droplet freely suspended in a linear shear field

    NASA Technical Reports Server (NTRS)

    Barthes-Biesel, D.; Acrivos, A.

    1973-01-01

    A theoretical method is presented for predicting the deformation and the conditions for breakup of a liquid droplet freely suspended in a general linear shear field. This is achieved by expanding the solution to the creeping-flow equations in powers of the deformation parameter epsilon and using linear stability theory to determine the onset of bursting. When compared with numerical solutions and with the available experimental data, the theoretical results are generally found to be of acceptable accuracy although, in some cases, the agreement is only qualitative.

  1. Dynamic Alignment at SLS

    SciTech Connect

    Ruland, Robert E.

    2003-04-23

    The relative alignment of components in the storage ring of the Swiss Light Source (SLS) is guaranteed by mechanical means. The magnets are rigidly fixed to 48 girders by means of alignment rails with tolerances of less than {+-}15 {micro}m. The bending magnets, supported by 3 point ball bearings, overlap adjacent girders and thus establish virtual train links between the girders, located near the bending magnet centres. Keeping the distortion of the storage ring geometry within a tolerance of {+-}100 {micro}m in order to guarantee sufficient dynamic apertures, requires continuous monitoring and correction of the girder locations. Two monitoring systems for the horizontal and the vertical direction will be installed to measure displacements of the train link between girders, which are due to ground settings and temperature effects: The hydrostatic levelling system (HLS) gives an absolute vertical reference, while the horizontal positioning system (HPS), which employs low cost linear encoders with sub-micron resolution, measures relative horizontal movements. The girder mover system based on five DC motors per girder allows a dynamic realignment of the storage ring within a working window of more than {+-}1 mm for girder translations and {+-}1 mrad for rotations. We will describe both monitoring systems (HLS and HPS) as well as the applied correction scheme based on the girder movers. We also show simulations indicating that beam based girder alignment takes care of most of the static closed orbit correction.

  2. Multiple protein structure alignment.

    PubMed Central

    Taylor, W. R.; Flores, T. P.; Orengo, C. A.

    1994-01-01

    A method was developed to compare protein structures and to combine them into a multiple structure consensus. Previous methods of multiple structure comparison have only concatenated pairwise alignments or produced a consensus structure by averaging coordinate sets. The current method is a fusion of the fast structure comparison program SSAP and the multiple sequence alignment program MULTAL. As in MULTAL, structures are progressively combined, producing intermediate consensus structures that are compared directly to each other and all remaining single structures. This leads to a hierarchic "condensation," continually evaluated in the light of the emerging conserved core regions. Following the SSAP approach, all interatomic vectors were retained with well-conserved regions distinguished by coherent vector bundles (the structural equivalent of a conserved sequence position). Each bundle of vectors is summarized by a resultant, whereas vector coherence is captured in an error term, which is the only distinction between conserved and variable positions. Resultant vectors are used directly in the comparison, which is weighted by their error values, giving greater importance to the matching of conserved positions. The resultant vectors and their errors can also be used directly in molecular modeling. Applications of the method were assessed by the quality of the resulting sequence alignments, phylogenetic tree construction, and databank scanning with the consensus. Visual assessment of the structural superpositions and consensus structure for various well-characterized families confirmed that the consensus had identified a reasonable core. PMID:7849601

  3. Docking alignment system

    NASA Technical Reports Server (NTRS)

    Monford, Leo G. (Inventor)

    1990-01-01

    Improved techniques are provided for alignment of two objects. The present invention is particularly suited for three-dimensional translation and three-dimensional rotational alignment of objects in outer space. A camera 18 is fixedly mounted to one object, such as a remote manipulator arm 10 of the spacecraft, while the planar reflective surface 30 is fixed to the other object, such as a grapple fixture 20. A monitor 50 displays in real-time images from the camera, such that the monitor displays both the reflected image of the camera and visible markings on the planar reflective surface when the objects are in proper alignment. The monitor may thus be viewed by the operator and the arm 10 manipulated so that the reflective surface is perpendicular to the optical axis of the camera, the roll of the reflective surface is at a selected angle with respect to the camera, and the camera is spaced a pre-selected distance from the reflective surface.

  4. Breakup Reactions and Exclusive Measurements in the {sup 6,7}Li+{sup 144}Sm Systems

    SciTech Connect

    Heimann, D. Martinez; Pacheco, A. J.; Arazi, A.; Figueira, J. M.; Negri, A. E.; Capurro, O. A.; Carnelli, P.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Testoni, J. E.; Monteiro, D. S.; Marta, H. D.

    2009-06-03

    The breakup of the projectile-like nuclei in reactions induced by 30 MeV {sup 6}Li and {sup 7}Li beams on a {sup 144}Sm target have been measured through the coincident detection of the in-plane emitted light particles. The primary ion that undergoes breakup has been identified and the physically meaningful variables that characterize the reaction have been obtained on a purely experimental basis. Distributions have been obtained for both the binary emission angle and for the breakup emission angle in the reference frame of the breakup products.

  5. Method for alignment of microwires

    DOEpatents

    Beardslee, Joseph A.; Lewis, Nathan S.; Sadtler, Bryce

    2017-01-24

    A method of aligning microwires includes modifying the microwires so they are more responsive to a magnetic field. The method also includes using a magnetic field so as to magnetically align the microwires. The method can further include capturing the microwires in a solid support structure that retains the longitudinal alignment of the microwires when the magnetic field is not applied to the microwires.

  6. Alignment as a Teacher Variable

    ERIC Educational Resources Information Center

    Porter, Andrew C.; Smithson, John; Blank, Rolf; Zeidner, Timothy

    2007-01-01

    With the exception of the procedures developed by Porter and colleagues (Porter, 2002), other methods of defining and measuring alignment are essentially limited to alignment between tests and standards. Porter's procedures have been generalized to investigating the alignment between content standards, tests, textbooks, and even classroom…

  7. Alignment as a Teacher Variable

    ERIC Educational Resources Information Center

    Porter, Andrew C.; Smithson, John; Blank, Rolf; Zeidner, Timothy

    2007-01-01

    With the exception of the procedures developed by Porter and colleagues (Porter, 2002), other methods of defining and measuring alignment are essentially limited to alignment between tests and standards. Porter's procedures have been generalized to investigating the alignment between content standards, tests, textbooks, and even classroom…

  8. Assessment of the Breakup of the Antarctic Polar Vortex in Two New Chemistry-Climate Models

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Li, F.; Morgenstern, O.; Braesicke, P.; Pyle, J. A.

    2010-01-01

    Successful simulation of the breakup of the Antarctic polar vortex depends on the representation of tropospheric stationary waves at Southern Hemisphere middle latitudes. This paper assesses the vortex breakup in two new chemistry-climate models (CCMs). The stratospheric version of the UK Chemistry and Aerosols model is able to reproduce the observed timing of the vortex breakup. Version 2 of the Goddard Earth Observing System (GEOS V2) model is typical of CCMs in that the Antarctic polar vortex breaks up too late; at 10 hPa, the mean transition to easterlies at 60 S is delayed by 12-13 days as compared with the ERA-40 and National Centers for Environmental Prediction reanalyses. The two models' skill in simulating planetary wave driving during the October-November period accounts for differences in their simulation of the vortex breakup, with GEOS V2 unable to simulate the magnitude and tilt of geopotential height anomalies in the troposphere and thus underestimating the wave driving. In the GEOS V2 CCM the delayed breakup of the Antarctic vortex biases polar temperatures and trace gas distributions in the upper stratosphere in November and December.

  9. Mechanism of Paleo-Mesoproterozoic rifts related to breakup of Columbia supercontinent: A paleostress field modeling

    NASA Astrophysics Data System (ADS)

    Sun, Shuai; Hou, Guiting; Hari, K. R.; Liu, Shuwen; Guan, Shuwei

    2017-06-01

    The Paleo-Mesoproterozoic Zhongtiao aulacogen in the North China Craton and Cuddapah basin in the Indian Craton, have both been interpreted as intra-continental rift formed by a mantle plume that led to the breakup of Columbia supercontinent, but the mechanism has not been completely deciphered. In this paper, the mechanism of the Zhongtiao aulacogen and Cuddapah basin related to initial breakup of Columbia has been evaluated with 2D elastic finite element models of the North China Craton and the Indian Craton. The trajectories of the horizontal maximum principal compressive stress of the best-fit model fit well with the trends of dyke swarms in the North China Craton and the Indian Craton. When the other three models generated were compared with the best-fit model, it can be found that a mantle plume beneath the Zhongtiao and Cuddapah areas played the most vital role in developing the Zhongtiao aulacogen, Cuddapah basin and initial breakup of Columbia supercontinent. The boundary subduction forces, including the northern margin of the NCC, the northwest and southwest margins of the Indian Craton are indispensable factors for the rifting and breakup, whereas the mechanical properties have little influence on these modeling results. The initial breakup of Columbia supercontinent might have been resulted from the coupling between a mantle plume upwelling and some plate tectonic forces.

  10. Robustness of free and pinned spiral waves against breakup by electrical forcing in excitable chemical media

    NASA Astrophysics Data System (ADS)

    Phantu, Metinee; Sutthiopad, Malee; Luengviriya, Jiraporn; Müller, Stefan C.; Luengviriya, Chaiya

    2017-04-01

    We present an investigation on the breakup of free and pinned spiral waves under an applied electrical current in the Belousov-Zhabotinsky reaction. Spiral fronts propagating towards the negative electrode are decelerated. A breakup of the spiral waves occurs when some segments of the fronts are stopped by a sufficiently strong electrical current. In the absence of obstacles (i.e., free spiral waves), the critical value of the electrical current for the wave breakup increases with the excitability of the medium. For spiral waves pinned to circular obstacles, the critical electrical current increases with the obstacle diameter. Analysis of spiral dynamics shows that the enhancement of the robustness against the breakup of both free and pinned spiral waves is originated by the increment of wave speed when either the excitability is strengthened or the obstacle size is enlarged. The experimental findings are reproduced by numerical simulations using the Oregonator model. In addition, the simulations reveal that the robustness against the forced breakup increases with the activator level in both cases of free and pinned spiral waves.

  11. Exclusive Measurements of Breakup Reactions in the {sup 7}Li+{sup 144}Sm System

    SciTech Connect

    Heimann, D. Martinez; Pacheco, A. J.; Arazi, A.; Figueira, J. M.; Negri, A.; Capurro, O. A.; Carnelli, P.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Testoni, J. E.; Monteiro, D. S.; Marta, H. D.

    2009-03-04

    Breakup reactions induced by a 30 MeV {sup 7}Li beam on a {sup 144}Sm target were measured through the coincident detection of the light particles emitted in the reaction plane. The emphasis of the measurements and data analysis was placed in the complete characterization of the reaction by means of the identification of the breakup products and the experimental extraction of the physically relevant magnitudes. The coincident yield of the emitted light particles was compared with the results of kinematical calculations that were done assuming different distributions for these magnitudes and taking into account the geometric response of the detection system. The results of this comparison indicate in all cases a clear dominance of a process compatible with the breakup of {sup 6}Li through the 3{sup +} resonant state at 2.186 MeV following one-neutron transfer from the projectile to the target, over the breakup of the projectile itself. Relative cross sections as a function of the emission angle of the {sup 6}Li and the in-plane anisotropy of the subsequent emission of breakup products were extracted from the data.

  12. Western Canadian Arctic ringed seal organic contaminant trends in relation to sea ice break-up.

    PubMed

    Gaden, A; Ferguson, Steve H; Harwood, L; Melling, H; Alikamik, J; Stern, G A

    2012-04-17

    The association between changing sea ice conditions and contaminant exposure to Arctic animals interests Inuvialuit harvesters, communities, and researchers. We examined organochlorine contaminant (OC) concentrations in the blubber of 90 male adult ringed seals (Phoca hispida) sampled from the subsistence harvest in Ulukhaktok (formerly Holman), NT, Canada, just prior to break-up of the sea ice (1993-2008). OC blubber concentrations were assessed with respect to year and sea ice break-up date. HCB and age- and blubber-adjusted concentrations of p,p'-DDT and ΣCHB (chlorobornane) significantly decreased over the study period. With respect to the timing of the spring break-up, highly lipophlic OCs, such as p,p'-DDE and PCB 153, were higher during years of early ice clearing (at least 12 days earlier than the mean annual break-up date), whereas no trends were observed for α, β, and γ isomers of HCH, trans- and cis-chlordane, oxychlordane, or ΣCHB. The higher contaminant concentrations found in earlier break-up years is likely due to earlier and/or increased foraging opportunities. This situation also has potential for enhancing bioaccumulation and biomagnification of contaminants over the long-term if projected changes continue to result in lighter and earlier ice conditions.

  13. Assessment of the Breakup of the Antarctic Polar Vortex in Two New Chemistry-Climate Models

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Li, F.; Morgenstern, O.; Braesicke, P.; Pyle, J. A.

    2010-01-01

    Successful simulation of the breakup of the Antarctic polar vortex depends on the representation of tropospheric stationary waves at Southern Hemisphere middle latitudes. This paper assesses the vortex breakup in two new chemistry-climate models (CCMs). The stratospheric version of the UK Chemistry and Aerosols model is able to reproduce the observed timing of the vortex breakup. Version 2 of the Goddard Earth Observing System (GEOS V2) model is typical of CCMs in that the Antarctic polar vortex breaks up too late; at 10 hPa, the mean transition to easterlies at 60 S is delayed by 12-13 days as compared with the ERA-40 and National Centers for Environmental Prediction reanalyses. The two models' skill in simulating planetary wave driving during the October-November period accounts for differences in their simulation of the vortex breakup, with GEOS V2 unable to simulate the magnitude and tilt of geopotential height anomalies in the troposphere and thus underestimating the wave driving. In the GEOS V2 CCM the delayed breakup of the Antarctic vortex biases polar temperatures and trace gas distributions in the upper stratosphere in November and December.

  14. Capillary thinning and breakup of saliva threads and rheological aging of mucin solutions

    NASA Astrophysics Data System (ADS)

    Wagner, Caroline; Bourouiba, Lydia; McKinley, Gareth

    2014-11-01

    The elasticity of saliva, which is essential for many of its primary functions such as lubrication, arises largely as a result of the presence of MUC5B mucins. These are large glycoproteins composed of numerous repeated polymeric subunits forming a weakly crosslinked network. It has been noted for nearly a century that once removed from the mouth, saliva quickly loses its elasticity, which can be quantified by a decrease in its capillary breakup time. We model saliva as a dilute finitely extensible nonlinear elastic (FENE-P) fluid with polymer chains composed of dispersed Hookean dumbbells of maximum extensibility b related to the number of MUC5B subunits. We show that under conditions of simple elongational flow, an analytic prediction of the time evolution of the radius and the filament breakup time can be derived. Furthermore, our model shows that decreasing the maximum extensibility b leads to a decrease in the breakup time, which suggests that the aging process of saliva outside the mouth involves a shortening of the MUC5B mucin chains into smaller groupings. Finally, we compare the analytic breakup times from the model with experimental results obtained using a capillary breakup extensional rheometer and human whole saliva.

  15. Neutron Induced D Breakup in Inertial Confinement Fusion at the Omega Laser Facility

    NASA Astrophysics Data System (ADS)

    Forrest, C. J.; Glebov, V. Yu.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.; Schroder, W. U.; Frenje, J. A.; Gatu Johnson, M.

    2015-11-01

    High-resolution neutron spectroscopy is used to study the deuteron breakup reaction D(n,n ') np in the thermonuclear environment created in inertial confinement fusion experiments at the Omega Laser Facility. Neutrons with an energy of 14.1 MeV generated in the primary D-T fusion reactions scatter elastically and inelastically off the dense (cryogenic) D-T fuel assembly surrounding the central hot spot at peak fuel compression. These neutrons also induce a breakup of the fuel deuterons. The corresponding breakup cross section is measured relative to elastic n -D and n -T scattering, i.e., simultaneously in the same environment. Apart from astrophysical and technological interest, the neutron-induced deuteron breakup reaction is of interest to the physics of nucleon -nucleon forces. For example, theoretical calculations predict a noticeable influence of nucleonic three-body forces on the magnitude of the breakup cross section. Preliminary results from measurements of the neutron contribution in the 2- to 6-MeV range show reasonable agreement with the published ENDL 2008.2 semi-empirical cross-section. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  16. Motion Planning Under Uncertainty In Highly Deformable Environments

    PubMed Central

    Patil, Sachin; van den, Jur; Alterovitz, Berg Ron

    2012-01-01

    Many tasks in robot-assisted surgery, food handling, manufacturing, and other applications require planning and controlling the motions of manipulators or other devices that must interact with highly deformable objects. We present a unified approach for motion planning under uncertainty in deformable environments that maximizes probability of success by accounting for uncertainty in deformation models, noisy sensing, and unpredictable actuation. Unlike prior planners that assume deterministic deformations or treat deformations as a type of small perturbation, our method explicitly considers the uncertainty in large, time-dependent deformations. Our method requires a simulator of deformable objects but places no significant restrictions on the simulator used. We use a sampling-based motion planner in conjunction with the simulator to generate a set of candidate plans based on expected deformations. Our method then uses the simulator and optimal control to numerically estimate time-dependent state distributions based on uncertain parameters (e.g. deformable material properties or actuation errors). We then select the plan with the highest estimated probability of successfully avoiding obstacles and reaching the goal region. Using FEM-based simulation of deformable tissues, we demonstrate the ability of our method to generate high quality plans in two medical-inspired scenarios: (1) guiding bevel-tip steerable needles through slices of deformable tissue around obstacles for minimally invasive biopsies and drug-delivery, and (2) manipulating planar tissues to align interior points at desired coordinates for precision treatment. PMID:25030775

  17. Physics-Based Modeling of Meteor Entry and Breakup

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kanq; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.; hide

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup. Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood. On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heat shields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kWcm2. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses.With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to

  18. Physics-Based Modeling of Meteor Entry and Breakup

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A.; Brandis, Aaron M.; Chen, Yih-Kanq; Jaffe, Richard L.; Saunders, David A.; Stern, Eric C.; Tauber, Michael E.; Venkatapathy, Ethiraj

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup. Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood. On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is less than 13 km/s (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/cm2. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to greater than 20 km/s; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current

  19. A Paleo-Mesoproterozoic supercontinent: assembly, growth and breakup

    NASA Astrophysics Data System (ADS)

    Zhao, Guochun; Sun, Min; Wilde, Simon A.; Li, Sanzhong

    2004-09-01

    northern margin of North China (Zhaertai-Bayan Obo Belt). The fragmentation corresponded with widespread anorogenic magmatic activity, forming anorthosite-mangerite-charnockite-granite (AMCG) suites in North America, Baltica, Amazonia and North China, and continued until the final breakup of the supercontinent at about 1.3-1.2 Ga, marked by the emplacement of the 1.27 Ga MacKenzie and 1.24 Ga Sudbury mafic dike swarms in North America.

  20. Physics-Based Modeling of Meteor Entry and Breakup

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.; Agrawal, Parul; Allen, Gary A., Jr.; Bauschlicher, Charles W., Jr.; Brandis, Aaron M.; Chen, Yih-Kang; Jaffe, Richard L.; Palmer, Grant E.; Saunders, David A.; Stern, Eric C.; hide

    2015-01-01

    A new research effort at NASA Ames Research Center has been initiated in Planetary Defense, which integrates the disciplines of planetary science, atmospheric entry physics, and physics-based risk assessment. This paper describes work within the new program and is focused on meteor entry and breakup.Over the last six decades significant effort was expended in the US and in Europe to understand meteor entry including ablation, fragmentation and airburst (if any) for various types of meteors ranging from stony to iron spectral types. These efforts have produced primarily empirical mathematical models based on observations. Weaknesses of these models, apart from their empiricism, are reliance on idealized shapes (spheres, cylinders, etc.) and simplified models for thermal response of meteoritic materials to aerodynamic and radiative heating. Furthermore, the fragmentation and energy release of meteors (airburst) is poorly understood.On the other hand, flight of human-made atmospheric entry capsules is well understood. The capsules and their requisite heatshields are designed and margined to survive entry. However, the highest speed Earth entry for capsules is 13 kms (Stardust). Furthermore, Earth entry capsules have never exceeded diameters of 5 m, nor have their peak aerothermal environments exceeded 0.3 atm and 1 kW/sq cm. The aims of the current work are: (i) to define the aerothermal environments for objects with entry velocities from 13 to 20 kms; (ii) to explore various hypotheses of fragmentation and airburst of stony meteors in the near term; (iii) to explore the possibility of performing relevant ground-based tests to verify candidate hypotheses; and (iv) to quantify the energy released in airbursts. The results of the new simulations will be used to anchor said risk assessment analyses. With these aims in mind, state-of-the-art entry capsule design tools are being extended for meteor entries. We describe: (i) applications of current simulation tools to

  1. Lithosphere erosion and breakup due to the interaction between extension and plume upwelling

    NASA Astrophysics Data System (ADS)

    Lavecchia, Alessio; Thieulot, Cedric; Beekman, Fred; Cloetingh, Sierd; Clark, Stuart

    2016-04-01

    We have built up 2D numerical models of coupled crust - lithospheric mantle - upper mantle systems. The reconstructed sections are subjected to external velocity fields and mantle plume impingement beneath the lithosphere, both acting simultaneously. The models are designed to simulate the interaction between plumes and lithosphere in an extensional setting with the main purpose to contribute to address the following questions: 1) Are plumes capable of weakening certain lithospheric regions? Where and when are the main effects observed? 2a) Can a plume really cause a plate break-off and drifting with no external contribution; 2b) if yes, are there any particularly favorable conditions required? In our models a novel aspect is melt generation due to plume, upper mantle and lithospheric mantle partial melting. Produced melts are capable to ascend across the reconstructed sections due to buoyancy. Furthermore, heat transport related to melt movement is taken into account and leads to a significant heating of host rocks at the melt neutral buoyancy depth. In absence of external stress or velocity fields, the effects of plume impingement beneath the lithosphere are negligible at surface. Here the main observed feature is the production of doming at various length scales, depending on the adopted rheology for the crust. At depth, the main effect is a thermo-mechanical erosion of the lithospheric mantle with production of melts and subsequent underplating of the crust. The heat flux due to plume impingement and crust underplating determines a weakening of crust and lithosphere. However, the strength drop is not followed by an appreciable deformation. When external stress or velocity fields are applied, the coupled effects with plume presence and melt production lead to great modifications of the lithospheric structure. Topography profiles are characterized by the presence of a horst and graben structure, and extensive erosion of the lithosphere always occurs. The presence

  2. Precision alignment and mounting apparatus

    NASA Technical Reports Server (NTRS)

    Preston, Dennis R. (Inventor)

    1993-01-01

    An alignment and mounting apparatus for mounting two modules (10,12) includes a first portion having a cylindrical alignment pin (16) projecting normal to a module surface, a second portion having a three-stage alignment guide (18) including a shoehorn flange (34), a Y-slot (42) and a V-block (22) which sequentially guide the alignment pin (16) with successively finer precision and a third portion in the form of a spring-loaded captive fastener (20) for connecting the two modules after alignment is achieved.

  3. Alignment of suprathermally rotating grains

    NASA Astrophysics Data System (ADS)

    Lazarian, A.

    1995-12-01

    It is shown that mechanical alignment can be efficient for suprathermally rotating grains, provided that they drift with supersonic velocities. Such a drift should be widely spread due to both Alfvenic waves and ambipolar diffusion. Moreover, if suprathermal rotation is caused by grain interaction with a radiative flux, it is shown that mechanical alignment may be present even in the absence of supersonic drift. This means that the range of applicability of mechanical alignment is wider than generally accepted and that it can rival the paramagnetic one. We also study the latter mechanism and re-examine the interplay between poisoning of active sites and desorption of molecules blocking the access to the active sites of H_2 formation, in order to explain the observed poor alignment of small grains and good alignment of large grains. To obtain a more comprehensive picture of alignment, we briefly discuss the alignment by radiation fluxes and by grain magnetic moments.

  4. Engineering cell alignment in vitro.

    PubMed

    Li, Yuhui; Huang, Guoyou; Zhang, Xiaohui; Wang, Lin; Du, Yanan; Lu, Tian Jian; Xu, Feng

    2014-01-01

    Cell alignment plays a critical role in various cell behaviors including cytoskeleton reorganization, membrane protein relocation, nucleus gene expression, and ECM remodeling. Cell alignment is also known to exert significant effects on tissue regeneration (e.g., neuron) and modulate mechanical properties of tissues including skeleton, cardiac muscle and tendon. Therefore, it is essential to engineer cell alignment in vitro for biomechanics, cell biology, tissue engineering and regenerative medicine applications. With advances in nano- and micro-scale technologies, a variety of approaches have been developed to engineer cell alignment in vitro, including mechanical loading, topographical patterning, and surface chemical treatment. In this review, we first present alignments of various cell types and their functionality in different tissues in vivo including muscle and nerve tissues. Then, we provide an overview of recent approaches for engineering cell alignment in vitro. Finally, concluding remarks and perspectives are addressed for future improvement of engineering cell alignment.

  5. TSGC and JSC Alignment

    NASA Technical Reports Server (NTRS)

    Sanchez, Humberto

    2013-01-01

    NASA and the SGCs are, by design, intended to work closely together and have synergistic Vision, Mission, and Goals. The TSGC affiliates and JSC have been working together, but not always in a concise, coordinated, nor strategic manner. Today we have a couple of simple ideas to present about how TSGC and JSC have started to work together in a more concise, coordinated, and strategic manner, and how JSC and non-TSG Jurisdiction members have started to collaborate: Idea I: TSGC and JSC Technical Alignment Idea II: Concept of Clusters.

  6. Self-Aligning Coupler

    NASA Technical Reports Server (NTRS)

    Cooney, Earl T.

    1990-01-01

    Joint reduces assembly time and eliminates fumbling. Self-aligning coupler easy to use for people wearing heavy gloves or other restrictive clothing. Consists of two threaded sections, one with blade, other with slot - joined by threaded collar. Blade fits precisely in slot. Notch in blade engages pin in slot to form temporary attachment. Collar turned on continuous thread of joined sections to form tight, rigid joint. Designed for assembly of structures by astronauts in space suits, coupler used on Earth by firefighters wearing protective garments, technicians handling hazardous materials, and others working underwater or in other difficult environments.

  7. Study of 10 Be and 16 C cluster structure by means of breakup reactions

    NASA Astrophysics Data System (ADS)

    Dell'Aquila, D.

    2016-03-01

    The study of cluster structures in nuclei far from stability represents a valid tool to explore the nuclear force in few-body systems. In this paper we discuss a new experimental investigation of the structure of 10Be and 16C nuclei by means of projectile sequential break-up reactions induced on CH2 target at intermediate-energies. Their spectroscopy is obtained via a relative energy analysis of break-up fragments with the CHIMERA multi-detector. From 4He+6He correlations we suggest the presence of a new state at about 13.5MeV in 10Be. The inspection of 6He+10Be break-up channel reveals the existence of a possible high-lying excited state at 20.6MeV in 16C. Finally, new perspectives concerning the improvement of the present results are discussed.

  8. The initiation of segmented buoyancy-driven melting during continental breakup

    NASA Astrophysics Data System (ADS)

    Gallacher, Ryan J.; Keir, Derek; Harmon, Nicholas; Stuart, Graham; Leroy, Sylvie; Hammond, James O. S.; Kendall, J.-Michael; Ayele, Atalay; Goitom, Berhe; Ogubazghi, Ghebrebrhan; Ahmed, Abdulhakim

    2016-10-01

    Melting of the mantle during continental breakup leads to magmatic intrusion and volcanism, yet our understanding of the location and dominant mechanisms of melt generation in rifting environments is impeded by a paucity of direct observations of mantle melting. It is unclear when during the rifting process the segmented nature of magma supply typical of seafloor spreading initiates. Here, we use Rayleigh-wave tomography to construct a high-resolution absolute three-dimensional shear-wave velocity model of the upper 250 km beneath the Afar triple junction, imaging the mantle response during progressive continental breakup. Our model suggests melt production is highest and melting depths deepest early during continental breakup. Elevated melt production during continental rifting is likely due to localized thinning and melt focusing when the rift is narrow. In addition, we interpret segmented zones of melt supply beneath the rift, suggesting that buoyancy-driven active upwelling of the mantle initiates early during continental rifting.

  9. The initiation of segmented buoyancy-driven melting during continental breakup.

    PubMed

    Gallacher, Ryan J; Keir, Derek; Harmon, Nicholas; Stuart, Graham; Leroy, Sylvie; Hammond, James O S; Kendall, J-Michael; Ayele, Atalay; Goitom, Berhe; Ogubazghi, Ghebrebrhan; Ahmed, Abdulhakim

    2016-10-18

    Melting of the mantle during continental breakup leads to magmatic intrusion and volcanism, yet our understanding of the location and dominant mechanisms of melt generation in rifting environments is impeded by a paucity of direct observations of mantle melting. It is unclear when during the rifting process the segmented nature of magma supply typical of seafloor spreading initiates. Here, we use Rayleigh-wave tomography to construct a high-resolution absolute three-dimensional shear-wave velocity model of the upper 250 km beneath the Afar triple junction, imaging the mantle response during progressive continental breakup. Our model suggests melt production is highest and melting depths deepest early during continental breakup. Elevated melt production during continental rifting is likely due to localized thinning and melt focusing when the rift is narrow. In addition, we interpret segmented zones of melt supply beneath the rift, suggesting that buoyancy-driven active upwelling of the mantle initiates early during continental rifting.

  10. Practical method to identify orbital anomaly as spacecraft breakup in the geostationary region

    NASA Astrophysics Data System (ADS)

    Uetsuhara, Masahiko; Hanada, Toshiya

    2013-09-01

    Identifying spacecraft breakup events is an essential issue for better understanding of the current orbital debris environment. This paper proposes an observation planning approach to identify an orbital anomaly, which appears as a significant discontinuity in archived orbital history, as a spacecraft breakup. The proposed approach is applicable to orbital anomalies in the geostationary region. The proposed approach selects a spacecraft that experienced an orbital anomaly, and then predicts trajectories of possible fragments of the spacecraft at an observation epoch. This paper theoretically demonstrates that observation planning for the possible fragments can be conducted. To do this, long-term behaviors of the possible fragments are evaluated. It is concluded that intersections of their trajectories will converge into several corresponding regions in the celestial sphere even if the breakup epoch is not specified and it has uncertainty of the order of several weeks.

  11. Disentangling unclear nuclear breakup channels of beryllium-9 using the three-axis Dalitz plot

    NASA Astrophysics Data System (ADS)

    Smith, R.; Freer, M.; Wheldon, C.; Curtis, N.; Almaraz-Calderon, S.; Aprahamian, A.; Ashwood, N. I.; Barr, M.; Bucher, B.; Copp, P.; Couder, M.; Fang, X.; Goldring, G.; Jung, F.; Kokalova, Tz; Lesher, S. R.; Lu, W.; Malcolm, J. D.; Roberts, A.; Tan, W. P.; Ziman, V. A.

    2017-06-01

    The three-axis Dalitz plot has been applied to the breakup of a nucleus into unequal mass fragments for the first time. The Dalitz plot allows clear identification of the various breakup channels of9Be → 2α + n process. The method has allowed the branching ratio for the 6.38 MeV level in9Be to be provisionally calculated when examining the9Be(4He, α)ααn reaction. The effects of non-uniform angular distributions on the Dalitz plot must still be properly investigated along with the effects of contaminant reaction channels. It is proposed that this method could be used to determine the breakup branching ratio of a newly-measured level in this nucleus.

  12. Characterization of the breakup of the Pegasus rocket body 1994-029B

    NASA Technical Reports Server (NTRS)

    Matney, Mark; Settecerri, Tom; Johnson, Nicholas; Stansbery, Eugene

    1997-01-01

    The breakup of a Pegasus hydrazine auxiliary propulsion system in June 1996, officially recognized as the worst satellite breakup in terms of cataloged debris, is considered. The fragmentation event is analyzed and it is discussed how these debris contribute to the current and future near earth space environment. The low altitude of the breakup and the large range of ejection velocities present concerns for other earth orbiting space vehicles, especially the Space Shuttle and the Hubble Space Telescope. In addition to orbit data collected by the U.S. Space Surveillance Network, observations were conducted with ground-based radar observatories. These observations show that the overabundance of debris is not limited to the trackable population, but also extends down to debris with sizes of less than 1 cm. Attempts to detect the debris with optical sensors were less successful.

  13. Formation of Long Tails during Breakup of Oil Droplets Mixed with Dispersants in Locally Isotropic Turbulence

    NASA Astrophysics Data System (ADS)

    Gopalan, Balaji; Katz, Joseph

    2008-11-01

    This study investigates experimentally, the effects of adding dispersants on the breakup of crude oil droplets in turbulent flows during oceanic spills. The current measurements are performed in a nearly homogeneous and isotropic turbulence facility, the central portion of which is characterized using 2-D PIV. Sample crude oil from Alaska National Slope is mixed with dispersant COREXIT 9527 and injected into the central portion of the turbulent facility. High speed, in-line digital holographic cinematography is utilized to visualize the breakup of droplets at high spatial and temporal resolution. We observe that, in some cases, after the droplet breaks up, the elongated portion of the droplet does not recoil, leaving an elongated tail, probably due to the low local surface tension. At high dispersant to oil ratios, extremely thin tails extend from the droplet, and are stretched by the flow. Breakup of these thin threads produces very small oil droplets, a desired effect during cleanup of oil spill.

  14. Droplet formation from the breakup of micron-sized liquid jets

    NASA Astrophysics Data System (ADS)

    van Hoeve, Wim; van der Bos, Arjan; Versluis, Michel; Snoeijer, Jacco; Brenner, Michael P.; Lohse, Detlef

    2009-11-01

    Droplet formation from the breakup of a liquid jet emerging from a micron-sized circular nozzle is investigated with ultra high-speed imaging at 1 million frames per second and within a lubrication approximation model [Eggers and Dupont, Phys. Rev. Lett. 262, 1994, 205-221]. The capillary time τc= √ρr^3 / γ is extremely small -- of the order of 1μs. In the analyzed low Reynolds number regime the jet breakup is driven by surface tension forces only. Rayleigh breakup is not influenced by the surrounding air. The high- speed imaging results and those from the model calculation perfectly agree for various liquid viscosities and jet velocities, confirming a universal scaling law also for diminutive Rayleigh jets.

  15. Oil slicks on water surface: Breakup, coalescence, and droplet formation under breaking waves.

    PubMed

    Nissanka, Indrajith D; Yapa, Poojitha D

    2017-01-15

    The ability to calculate the oil droplet size distribution (DSD) and its dynamic behavior in the water column is important in oil spill modeling. Breaking waves disperse oil from a surface slick into the water column as droplets of varying sizes. Oil droplets undergo further breakup and coalescence in the water column due to the turbulence. Available models simulate oil DSD based on empirical/equilibrium equations. However, the oil DSD evolution due to subsequent droplet breakup and coalescence in the water column can be best represented by a dynamic population model. This paper develops a phenomenological model to calculate the oil DSD in wave breaking conditions and ocean turbulence and is based on droplet breakup and coalescence. Its results are compared with data from laboratory experiments that include different oil types, different weathering times, and different breaking wave heights. The model comparisons showed a good agreement with experimental data.

  16. Fluid breakup in carbon nanotubes: An explanation of ultrafast ion transport

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Zhao, Tianshou; Li, Zhigang

    2017-09-01

    Ultrafast ion transport in carbon nanotubes (CNTs) has been experimentally observed, but the underlying mechanism is unknown. In this work, we investigate ion transport in CNTs through molecular dynamics (MD) simulations. It is found that the flow in CNTs undergoes a transition from the passage of a continuous liquid chain to the transport of isolated ion-water clusters as the CNT length or the external electric filed strength is increased. The breakup of the liquid chain in CNTs greatly reduces the resistance caused by the hydrogen bonds of water and significantly enhances the ionic mobility, which explains the two-order-magnitude enhancement of ionic conductance in CNTs reported in the literature. A theoretical criterion for fluid breakup is proposed, which agrees well with MD results. The fluid breakup phenomenon provides new insights into enhancing ion transport in nanoconfinements.

  17. Three-body breakup in dissociative electron attachment to the water molecule

    SciTech Connect

    Haxton, Daniel J.; Rescigno, Thomas N.; McCurdy, C. William

    2008-08-28

    We report the results of {\\em ab initio} calculations on dissociative electron attachment (DEA) to water that demonstrate the importance of including three-body breakup in the dissociation dynamics. While three-body breakup is ubiquitous in the analogous process of dissociative recombination, its importance in low-energy dissociative electron attachment to a polyatomic target has not previously been quantified. Our calculations, along with our earlier studies of DEA into two-body channels, indicate that three-body breakup is a major component of the observed O- cross section. The local complex potential model provides a generally accurate picture of the experimentallyobserved features in this system, reproducing some quantitatively, others qualitatively, and one not at all.

  18. Proton-Deuteron Break-Up Measurements with Bina at 135 MeV

    NASA Astrophysics Data System (ADS)

    Eslami-Kalantari, M.; Amir-Ahmadi, H. R.; Biegun, A.; Gašparić, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Moeini, H.; Ramazani-Moghaddam-Arani, A.; Shende, S. V.; Stephan, E.; Sworst, R.

    High-precision measurements of the proton-deuteron elastic and break-up reaction have been performed in the past at KVI and elsewhere with the aim to study three-nucleon force (3NF) effects. In the present work, we explored 3NF effects in the break-up scattering process by performing a measurement of vector analyzing powers and differential cross sections using a 135 MeV polarized-proton beam impinging on a liquid-deuterium target. For this study, we used a new experimental setup, Big Instrument for Nuclear-polarization Analysis, BINA, which covers almost the entire kinematical phase space of the break-up reaction. The results are interpreted with the help of state-of-the-art Faddeev calculations.

  19. Measurements of scattering observables for the pd break-up reaction

    NASA Astrophysics Data System (ADS)

    Eslami-Kalantari, M.; Amir-Ahmadi, H. R.; Biegun, A.; Gašparic, I.; Joulaeizadeh, L.; Kalantar-Nayestanaki, N.; Kistryn, St.; Kozela, A.; Mardanpour, H.; Messchendorp, J. G.; Moeini, H.; Ramazani-Moghaddam-Arani, A.; Shende, S. V.; Stephan, E.; Sworst, R.

    2010-04-01

    High-precision measurements of the scattering observables such as cross sections and analyzing powers for the proton-deuteron elastic and break-up reactions have been performed at KVI in the last two decades and elsewhere to investigate various aspects of the three-nucleon force (3NF) effects simultaneously. In 2006 an experiment was performed to study these effects in p+d break-up reaction at 135 MeV with the detection system, Big Instrument for Nuclear polarization Analysis, BINA. BINA covers almost the entire kinematical phase space of the break-up reaction. The results are interpreted with the help of state-of-the-art Faddeev calculations and are partly presented in this contribution.

  20. Instability of nano- and microscale liquid metal filaments: Transition from single droplet collapse to multidroplet breakup

    SciTech Connect

    Hartnett, Chris A.; Mahady, Kyle; Fowlkes, Jason Davidson; Afkhami, Shahriar; Rack, P. D.; Kondic, L.

    2015-11-23

    We carry out experimental and numerical studies to investigate the collapse and breakup of finite size, nano- and microscale, liquid metal filaments supported on a substrate. We find the critical dimensions below which filaments do not break up but rather collapse to a single droplet. The transition from collapse to breakup can be described as a competition between two fluid dynamic phenomena: the capillary driven end retraction and the Rayleigh–Plateau type instability mechanism that drives the breakup. We focus on the unique spatial and temporal transition region between these two phenomena using patterned metallic thin film strips and pulsed-laser-induced dewetting. The experimental results are compared to an analytical model proposed by Driessen et al. and modified to include substrate interactions. Additionally, we report the results of numerical simulations based on a volume-of-fluid method to provide additional insight and highlight the importance of liquid metal resolidification, which reduces inertial effects.

  1. Combining many multiple alignments in one improved alignment.

    PubMed

    Bucka-Lassen, K; Caprani, O; Hein, J

    1999-02-01

    The fact that the multiple sequence alignment problem is of high complexity has led to many different heuristic algorithms attempting to find a solution in what would be considered a reasonable amount of computation time and space. Very few of these heuristics produce results that are guaranteed always to lie within a certain distance of an optimal solution (given a measure of quality, e.g. parsimony). Most practical heuristics cannot guarantee this, but nevertheless perform well for certain cases. An alignment, obtained with one of these heuristics and with a bad overall score, is not unusable though, it might contain important information on how substrings should be aligned. This paper presents a method that extracts qualitatively good sub-alignments from a set of multiple alignments and combines these into a new, often improved alignment. The algorithm is implemented as a variant of the traditional dynamic programming technique. An implementation of ComAlign (the algorithm that combines multiple alignments) has been run on several sets of artificially generated sequences and a set of 5S RNA sequences. To assess the quality of the alignments obtained, the results have been compared with the output of MSA 2.1 (Gupta et al., Proceedings of the Sixth Annual Symposium on Combinatorial Pattern Matching, 1995; Kececioglu et al., http://www.techfak.uni-bielefeld. de/bcd/Lectures/kececioglu.html, 1995). In all cases, ComAlign was able to produce a solution with a score comparable to the solution obtained by MSA. The results also show that ComAlign actually does combine parts from different alignments and not just select the best of them. The C source code (a Smalltalk version is being worked on) of ComAlign and the other programs that have been implemented in this context are free and available on WWW (http://www.daimi.au.dk/ õcaprani). klaus@bucka-lassen.dk; jotun@pop.bio.au.dk;ocaprani@daimi.au.dk

  2. Preventing alternans-induced spiral wave breakup in cardiac tissue: An ion-channel-based approach

    NASA Astrophysics Data System (ADS)

    Allexandre, D.; Otani, N. F.

    2004-12-01

    The detailed processes involved in spiral wave breakup, believed to be one major mechanism by which tachycardia evolves into fibrillation, are still poorly understood. This has rendered difficult the proper design of an efficient and practical control stimulus protocol to eliminate such events. In order to gain new insights into the underlying electrophysiological and dynamical mechanisms of breakup, we applied linear perturbation theory to a steadily rotating spiral wave in two spatial dimensions. The tissue was composed of cells modeled using the Fenton-Karma equations whose parameters were chosen to emphasize alternans as a primary mechanism for breakup. Along with one meandering mode, not just one but several unstable alternans modes were found with differing growth rates, frequencies, and spatial structures. As the conductance of the fast inward current was increased, the instability of the modes increased, consistent with increased meandering and propensity for spiral breakup in simulations. We also explored a promising new approach, based on the theory, for the design of an energy efficient electrical stimulus protocol to control spiral wave breakup. The novelty lies in addressing the problem directly at the ion channel level and taking advantage of the inherent two dimensional nature of the rotating wave. With the help of the eigenmode method, we were able to calculate the exact timing and amplitude of the stimulus, and locate it optimally to maximize efficiency. The analysis led to a special-case example that demonstrated that a single, properly timed stimulus can have a global effect, suppressing all growing alternans modes over the entire tissue, thus inhibiting spiral wave breakup.

  3. The Dispersal of East Gondwana from Continental Breakup to the Start of the Cretaceous Quiet Zone

    NASA Astrophysics Data System (ADS)

    Davis, J. K.; Lawver, L. A.; Norton, I. O.; Gahagan, L.

    2014-12-01

    Existing plate models for the breakup of Africa and East Gondwana (Australia, East Antarctica, India, Madagascar, the Seychelles, and Sri Lanka) are problematic and require revision. Specific problems include the utilization of dubious Gondwana configurations, improbable plate motion, and/or a failure to satisfy the holistic marine magnetic anomaly data. I present here a new model for the breakup of East Gondwana. This new model begins from a constrained, pre-breakup, Gondwana configuration. Out of this initial "tight-fit" configuration, East Gondwana rifts from West Gondwana (Africa & South America) as a cohesive unit. During this breakup and subsequent seafloor spreading, East Gondwana is devoid of any internal compression or anomalous plate motion. The overall motion of East Gondwana is constrained by seafloor spreading in the coeval Somali Basin and Mozambique/Riiser Larsen Basins. Seafloor spreading in these basins is modeled using existing marine magnetic anomaly interpretations and satellite-derived gravity data. Our model is uniquely able to satisfy the magnetic anomaly observations in both of the aforementioned basins without invoking improbable plate motion or configurations. Additionally, our plate model provides valuable insight into the breakup of India and East Antarctica. In this model, we fix India to Madagascar from breakup to 90 Ma, thus eventual separation between India and East Antarctica is an output, not an input of our model. We suggest that this separation occurred diachronously from ~140 Ma in the east to ~120 Ma in the west. This modeled motion between India and East Antarctica agrees well with geophysical observations from the margin of East Antarctica and our preliminary analysis of margin character and variability.

  4. Mechanisms of free-surface breakup in vibration-induced liquid atomization

    NASA Astrophysics Data System (ADS)

    Vukasinovic, Bojan; Smith, Marc K.; Glezer, Ari

    2007-01-01

    The mechanisms of droplet formation that take place during vibration-induced drop atomization are investigated experimentally. Droplet ejection results from the breakup of transient liquid spikes that form following the localized collapse of free-surface waves. Breakup typically begins with capillary pinch-off of a droplet from the tip of the spike and can be followed by additional pinch-offs of satellite droplets if the corresponding capillary number is sufficiently small (e.g., in low-viscosity liquids). If the capillary number is increased (e.g., in viscous liquids), breakup first occurs near the base of the spike, with or without subsequent breakup of the detached, thread-like spike. The formation of these detached threads is governed by a breakup mechanism that is separated from the tip-dominated capillary pinch-off mechanism by an order of magnitude in terms of dimensionless driving frequency f*. The dependence of breakup time and unbroken spike length on fluid and driving parameters is established over a broad range of dimensionless driving frequencies (10-3

  5. On jet impingement and thin film breakup on a horizontal superhydrophobic surface

    NASA Astrophysics Data System (ADS)

    Prince, Joseph F.; Maynes, Daniel; Crockett, Julie

    2015-11-01

    When a vertical laminar jet impinges on a horizontal surface, it will spread out in a thin film. If the surface is hydrophobic and a downstream depth is not maintained, the film will radially expand until it breaks up into filaments or droplets. We present the first analysis and model that describes the location of this transition for both isotropic and anisotropic structured superhydrophobic (SH) surfaces. All surfaces explored are hydrophobic or SH, where the SH surfaces exhibit an apparent slip at the plane of the surface due to a shear free condition above the air filled cavities between the structures. The influence of apparent slip on the entire flow field is significant and yields behavior that deviates notably from classical behavior for a smooth hydrophilic surface where a hydraulic jump would form. Instead, break up into droplets occurs where the jet's outward radial momentum is balanced by the inward surface tension force of the advancing film. For hydrophobic surfaces, or SH surfaces with random micropatterning, the apparent slip on the surface is uniform in all directions and droplet breakup occurs in a circular pattern. When alternating rib/cavity microstructures are used to create the SH surface, the apparent slip varies as a function of the azimuthal coordinate, and thus, the breakup location is elliptically shaped. The thin film dynamics are modeled by a radial momentum analysis for a given jet Weber number and specified slip length and the location of breakup for multiple surfaces over a range of jet Weber numbers and realistic slip length values is quantified. The results of the analysis show that the breakup radius increases with increasing Weber number and slip length. The eccentricity of the breakup ellipse for the rib/cavity SH structures increases with increasing Weber number and slip length as well. A generalized model that allows prediction of the transition (break-up) location as a function of all influencing parameters is presented

  6. Post-breakup burial and exhumation of passive continental margins: nine propositions to inform geodynamic models

    NASA Astrophysics Data System (ADS)

    Green, Paul F.; Duddy, Ian; Japsen, Peter; Chalmers, James; Bonow, Johan

    2017-04-01

    Despite many years of study, the processes involved in the post-breakup development of passive margins remain poorly understood. Integration of apatite fission track analysis (AFTA) and stratigraphic landscape analysis (SLA) at a number of margins has provided new insights into the development of elevated passive continental margins (EPCMs). In particular, these studies have highlighted the importance of integrating evidence from the preserved rock record with information on the deposition and erosional removal of rock units which are no longer present ("missing section"). From these studies we have formulated nine propositions regarding the formation of EPCMs and the nature of the controlling processes, viz: 1: EPCMs are not the inevitable consequence of rifting and breakup 2: Elevated topography at present-day EPCMs developed long after breakup 3: Similar EPCM landscapes at different margins suggest similar controlling processes 4: EPCMs undergo episodic burial and exhumation rather than slow monotonic denudation, both before rifting and after breakup 5: Post-breakup exhumation at continental margins is not restricted to elevated onshore regions 6: Post-breakup burial and exhumation have affected low lying margins as well as EPCMs 7: Episodic km-scale exhumation and re-burial also affects cratonic regions 8: Exhumation events show a broad level of synchroneity across continents and oceans and correlate with plate boundary events and changes in plate motions. 9: EPCMs are located where there is an abrupt, lateral change in crustal or lithospheric thickness These propositions imply that positive and negative vertical motions at passive margins are controlled by plate-scale processes. Many of these key aspects are absent from current geodynamic models of passive margin development. Understanding the processes that control vertical movements at passive continental margins requires development of realistic geodynamic models that honour these propositions.

  7. On the driving forces of the Pangea breakup and northward drift of the Indian subcontinent

    NASA Astrophysics Data System (ADS)

    Yoshida, Masaki; Hamano, Yozo

    2015-04-01

    During the breakup of the supercontinent Pangea, the Indian subcontinent became isolated from the southern part of Pangea, called Gondwanaland, at around 130 Ma, moved northwards, and eventually collided with Eurasia to form the Himalayas at around 40-50 Ma. The reason why the Indian subcontinent moved at such a high speed of up to c. 20 cm/yr remains a controversial issue in geodynamics. Here, numerical simulation of 3-D spherical mantle convection with an Earth-like Rayleigh number is reported, considering the assembly of highly viscous continental blocks with the configuration of Pangea, to determine the geodynamic mechanisms of the Pangea breakup, the subsequent continental drift, and the high-speed northward drift of the Indian subcontinent. Our numerical simulations approximately reproduced the process of continental drift from the breakup of Pangea at 200 Ma to the present-day continental distribution. These simulations revealed that a major factor in the northward drift of the Indian subcontinent was the large-scale cold mantle downwelling that developed spontaneously in the North Tethys Ocean, attributed to the overall shape of Pangea. The strong lateral mantle flow caused by the high-temperature anomaly beneath Pangea, due to the thermal insulation effect, enhanced the acceleration of the Indian subcontinent during the early stage of the Pangea breakup. The large-scale hot upwelling plumes from the lower mantle, initially located under Africa, might have contributed to the formation of the large-scale cold mantle downwelling in the North Tethys Ocean. References: [1] Yoshida, M., Effects of various lithospheric yield stresses and different mantle-heating modes on the breakup of the Pangea supercontinent, Geophys. Res. Lett., 41(9), 3060-3067, doi:10.1002/2014GL060023, 2014. [2] Yoshida, M. and Y. Hamano, Pangea breakup and northward drift of the Indian subcontinent reproduced by a numerical model of mantle convection, Submitted to Scientific Reports, 2015

  8. Monitoring ice break-up on the Mackenzie River using MODIS data

    NASA Astrophysics Data System (ADS)

    Muhammad, P.; Duguay, C.; Kang, K.-K.

    2016-03-01

    The aim of this study was to develop an approach for estimating ice break-up dates on the Mackenzie River (MR) using more than a decade of MODIS Level 3 500 m snow products (MOD/MYD10A1), complemented with 250 m Level 1B radiance products (MOD/MYD02QKM) from the Terra and Aqua satellite platforms. The analysis showed break-up began on average between days of year (DOYs) 115 and 125 and ended between DOYs 145 and 155 over 13 ice seasons (2001-2013), resulting in an average melt duration of ca. 30-40 days. Thermal processes were more important in driving ice break-up south of the MR confluence with the Liard River, while dynamically driven break-up was more important north of the Liard. A comparison of the timing of ice disappearance with snow disappearance from surrounding land areas of the MR with MODIS Level 3 snow products showed varying relationships along the river. Ice-off and snow-off timing were in sync north of the MR-Liard River confluence and over sections of the MR before it enters the Mackenzie Delta, but ice disappeared much later than snow on land in regions where thermal ice break-up processes dominated. MODIS observations revealed that channel morphology is a more important control of ice break-up patterns than previously believed with ice runs on the MR strongly influenced by channel morphology (islands and bars, confluences and channel constriction). Ice velocity estimates from feature tracking were able to be made in 2008 and 2010 and yielded 3-4-day average ice velocities of 1.21 and 1.84 m s-1 respectively, which is in agreement with estimates from previous studies. These preliminary results confirm the utility of daily MODIS data for monitoring ice break-up processes along the Mackenzie River. The addition of optical and synthetic aperture radar data from recent and upcoming satellite missions (e.g. Sentinel-1/2/3 and RADARSAT Constellation) would improve the monitoring of ice break-up in narrower sections of the MR.

  9. Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al

    SciTech Connect

    Figueira, J. M.; Niello, J. O. Fernandez; Abriola, D.; Arazi, A.; Capurro, O. A.; Barbara, E. de; Marti, G. V.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Padron, I.; Gomes, P. R. S.; Lubian, J.; Correa, T.; Paes, B.

    2007-01-15

    Elastic scattering of the weakly bound {sup 6}Li on {sup 27}Al was measured at near-barrier energies. The data analysis was performed using a Woods-Saxon shape optical potential and also using the double-folding Sao Paulo potential. The results show the presence of the breakup threshold anomaly (BTA), an anomalous behavior when compared with the scattering of tightly bound nuclei. This behavior is attributed to a repulsive polarization potential produced by the coupling to the continuum breakup states.

  10. Sparking limits, cavity loading, and beam breakup instability associated with high-current rf linacs

    SciTech Connect

    Faehl, R.J.; Lemons, D.S.; Thode, L.E.

    1982-01-01

    The limitations on high-current rf linacs due to gap sparking, cavity loading, and the beam breakup instability are studied. It appears possible to achieve cavity accelerating gradients as high as 35 MV/m without sparking. Furthermore, a linear analysis, as well as self-consistent particle simulations of a multipulsed 10 kA beam, indicated that only a negligible small fraction of energy is radiated into nonfundamental cavity modes. Finally, the beam breakup instability is analyzed and found to be able to magnify initial radial perturbations by a factor of no more than about 20 during the beam transit time through a 1 GeV accelerator.

  11. Breakup and Elastic Scattering in the {sup 9}Be + {sup 144}Sm system at near barrier energies

    SciTech Connect

    Paes, B.; Garcia, V. N.; Lubian, J.; Gomes, P. R. S.; Padron, I.

    2010-05-21

    Breakup and elastic scattering in the Be + {sup 144}Sm system, at near barrier energies, are investigated. We calculate theoretically the non-capture breakup cross section by performing coupled reaction channel calculations. The energy dependence of the optical potential does not show the usual threshold anomaly found in tightly bound systems.

  12. Windswept lower limb deformities in patients with hypophosphataemic rickets.

    PubMed

    Al Kaissi, Ali; Farr, Sebastian; Ganger, Rudolf; Klaushofer, Klaus; Grill, Franz

    2013-12-06

    X-linked hypophosphataemic rickets is an X-linked dominant disorder that is secondary to renal phosphate-wasting. Genu varum and/or genu valgum have been described as the most common deformities in patients with hypophosphataemic rickets. Windswept deformity, which is valgus deformity in one knee and varus deformity in the other, was the most common deformity encountered in our department. We collected seven patients who had phenotypic and genotypic features consistent with the diagnosis of X-linked hypophosphataemic rickets. All presented with windswept lower limb deformity. We discuss the phenotypic and genotypic correlation, and the surgical procedures applied. Surgical interventions were scheduled to correct the triad of appearance, function and biomechanics. Re-alignment orthopaedic measures were applied to correct and to restore normal growth and development in these children. Post-operative measurements showed dramatic improvements in balance and gait. The most common deformity seen in patients with hypophosphataemic rickets is gradual anetrolateral bowing of the femur combined with tibia vara. Windswept lower limb deformity was the most common angular deformity in our patients with hypophosphataemic rickets. Baseline skeletal surveys and genotypic characterisation were subject to close scrutiny and assessment, with the aim of proper diagnosis and treatment. Nevertheless, recurrence of deformity is a common sequel and younger patients have a higher risk for recurrence.

  13. Deformations in VLBI antennas

    NASA Technical Reports Server (NTRS)

    Clark, T. A.; Thomsen, P.

    1988-01-01

    A study is presented of deformations in antennas with the emphasis on their influence on VLBI measurements. The GIFTS structural analysis program has been used to model the VLBI antenna in Fairbanks (Alaska). The report identifies key deformations and studies the effect of gravity, wind, and temperature. Estimates of expected deformations are given.

  14. Neuropathic midfoot deformity: associations with ankle and subtalar joint motion

    PubMed Central

    2013-01-01

    Background Neuropathic deformities impair foot and ankle joint mobility, often leading to abnormal stresses and impact forces. The purpose of our study was to determine differences in radiographic measures of hind foot alignment and ankle joint and subtalar joint motion in participants with and without neuropathic midfoot deformities and to determine the relationships between radiographic measures of hind foot alignment to ankle and subtalar joint motion in participants with and without neuropathic midfoot deformities. Methods Sixty participants were studied in three groups. Forty participants had diabetes mellitus (DM) and peripheral neuropathy (PN) with 20 participants having neuropathic midfoot deformity due to Charcot neuroarthropathy (CN), while 20 participants did not have deformity. Participants with diabetes and neuropathy with and without deformity were compared to 20 young control participants without DM, PN or deformity. Talar declination and calcaneal inclination angles were assessed on lateral view weight bearing radiograph. Ankle dorsiflexion, plantar flexion and subtalar inversion and eversion were assessed by goniometry. Results Talar declination angle averaged 34±9, 26±4 and 23±3 degrees in participants with deformity, without deformity and young control participants, respectively (p< 0.010). Calcaneal inclination angle averaged 11±10, 18±9 and 21±4 degrees, respectively (p< 0.010). Ankle plantar flexion motion averaged 23±11, 38±10 and 47±7 degrees (p<0.010). The association between talar declination and calcaneal inclination angles with ankle plantar flexion range of motion is strongest in participants with neuropathic midfoot deformity. Participants with talonavicular and calcaneocuboid dislocations result in the most severe restrictions in ankle joint plantar flexion and subtalar joint inversion motions. Conclusions An increasing talar declination angle and decreasing calcaneal inclination angle is associated with decreases in ankle

  15. Neuropathic midfoot deformity: associations with ankle and subtalar joint motion.

    PubMed

    Sinacore, David R; Gutekunst, David J; Hastings, Mary K; Strube, Michael J; Bohnert, Kathryn L; Prior, Fred W; Johnson, Jeffrey E

    2013-03-25

    Neuropathic deformities impair foot and ankle joint mobility, often leading to abnormal stresses and impact forces. The purpose of our study was to determine differences in radiographic measures of hind foot alignment and ankle joint and subtalar joint motion in participants with and without neuropathic midfoot deformities and to determine the relationships between radiographic measures of hind foot alignment to ankle and subtalar joint motion in participants with and without neuropathic midfoot deformities. Sixty participants were studied in three groups. Forty participants had diabetes mellitus (DM) and peripheral neuropathy (PN) with 20 participants having neuropathic midfoot deformity due to Charcot neuroarthropathy (CN), while 20 participants did not have deformity. Participants with diabetes and neuropathy with and without deformity were compared to 20 young control participants without DM, PN or deformity. Talar declination and calcaneal inclination angles were assessed on lateral view weight bearing radiograph. Ankle dorsiflexion, plantar flexion and subtalar inversion and eversion were assessed by goniometry. Talar declination angle averaged 34±9, 26±4 and 23±3 degrees in participants with deformity, without deformity and young control participants, respectively (p< 0.010). Calcaneal inclination angle averaged 11±10, 18±9 and 21±4 degrees, respectively (p< 0.010). Ankle plantar flexion motion averaged 23±11, 38±10 and 47±7 degrees (p<0.010). The association between talar declination and calcaneal inclination angles with ankle plantar flexion range of motion is strongest in participants with neuropathic midfoot deformity. Participants with talonavicular and calcaneocuboid dislocations result in the most severe restrictions in ankle joint plantar flexion and subtalar joint inversion motions. An increasing talar declination angle and decreasing calcaneal inclination angle is associated with decreases in ankle joint plantar flexion motion in

  16. Theoretical analysis and simulation of obstructed breakup of micro-droplet in T-junction under an asymmetric pressure difference

    NASA Astrophysics Data System (ADS)

    Fu, Yuhang; Bai, Lin; Jin, Yong; Cheng, Yi

    2017-03-01

    Asymmetric droplet breakup under a pressure difference at two outlets of a T-junction is investigated theoretically and numerically in this study. An accurate analysis of the evolution of droplet dynamics during the obstructed breakup process has been conducted. Meanwhile, the lattice Boltzmann method based on color gradient model is employed to simulate the system with the verification of the theoretical results. It is demonstrated that the Zou-He boundary setting at each outlet is advantageous for modifying the pressure drop of the two branches of T-junction. The results reveal that asymmetric breakup of the unequally sized droplets follows two steps, namely, the filling stage and the breakup stage. Then a universal parameter is proposed to describe the asymmetric condition of droplet breakup in T-junction, which plays a key role to characterize the temporal evolution of volume ratio and the droplet length of formed smaller droplets.

  17. Importance of the continuum-continuum couplings in the 6Li elastic breakup on different target masses

    NASA Astrophysics Data System (ADS)

    Mukeru, B.; Lekala, M. L.

    2017-09-01

    A theoretical study of 6Li breakup on target masses ranging from A = 58 to 208 is performed. It is obtained that when continuum-continuum couplings are included in the potential coupling matrix, they substantially reduce the total and nuclear breakup cross sections, while the Coulomb breakup cross sections for the medium and heavy target masses are increased. When these couplings are excluded, we show that the total and nuclear breakup cross sections depend linearly on AT1/3, namely they decrease linearly as the mass of the target increases. In the same case, the Coulomb breakup cross section depends linearly with the charge of the target ZT (decreases as ZT increases). We found that this linearity is destroyed when these couplings are included. However, in this case, it is the Coulomb-nuclear interference that also depends linearly with the target charge (increase with ZT).

  18. Alignment between seafloor spreading directions and absolute plate motions through time

    NASA Astrophysics Data System (ADS)

    Williams, Simon E.; Flament, Nicolas; Müller, R. Dietmar

    2016-02-01

    The history of seafloor spreading in the ocean basins provides a detailed record of relative motions between Earth's tectonic plates since Pangea breakup. Determining how tectonic plates have moved relative to the Earth's deep interior is more challenging. Recent studies of contemporary plate motions have demonstrated links between relative plate motion and absolute plate motion (APM), and with seismic anisotropy in the upper mantle. Here we explore the link between spreading directions and APM since the Early Cretaceous. We find a significant alignment between APM and spreading directions at mid-ocean ridges; however, the degree of alignment is influenced by geodynamic setting, and is strongest for mid-Atlantic spreading ridges between plates that are not directly influenced by time-varying slab pull. In the Pacific, significant mismatches between spreading and APM direction may relate to a major plate-mantle reorganization. We conclude that spreading fabric can be used to improve models of APM.

  19. Nova laser alignment control system

    SciTech Connect

    Van Arsdall, P.J.; Holloway, F.W.; McGuigan, D.L.; Shelton, R.T.

    1984-03-29

    Alignment of the Nova laser requires control of hundreds of optical components in the ten beam paths. Extensive application of computer technology makes daily alignment practical. The control system is designed in a manner which provides both centralized and local manual operator controls integrated with automatic closed loop alignment. Menudriven operator consoles using high resolution color graphics displays overlaid with transport touch panels allow laser personnel to interact efficiently with the computer system. Automatic alignment is accomplished by using image analysis techniques to determine beam references points from video images acquired along the laser chain. A major goal of the design is to contribute substantially to rapid experimental turnaround and consistent alignment results. This paper describes the computer-based control structure and the software methods developed for aligning this large laser system.

  20. Functional Alignment of Metabolic Networks.

    PubMed

    Mazza, Arnon; Wagner, Allon; Ruppin, Eytan; Sharan, Roded

    2016-05-01

    Network alignment has become a standard tool in comparative biology, allowing the inference of protein function, interaction, and orthology. However, current alignment techniques are based on topological properties of networks and do not take into account their functional implications. Here we propose, for the first time, an algorithm to align two metabolic networks by taking advantage of their coupled metabolic models. These models allow us to assess the functional implications of genes or reactions, captured by the metabolic fluxes that are altered following their deletion from the network. Such implications may spread far beyond the region of the network where the gene or reaction lies. We apply our algorithm to align metabolic networks from various organisms, ranging from bacteria to humans, showing that our alignment can reveal functional orthology relations that are missed by conventional topological alignments.