Science.gov

Sample records for aligned breakup deformation

  1. Deformation and secondary breakup of drops

    NASA Astrophysics Data System (ADS)

    Hsiang, L.-P.; Faeth, G. M.

    1993-01-01

    Drop properties during and after secondary breakup in the bag, multimode and shear breakup regimes were observed for shock wave initiated disturbances in air at normal temperature and pressure. Test liquids included water, n-heptane, ethyl alcohol and glycerol mixtures to yield Weber numbers of 15-600. Ohnesorge numbers of 0.0025-0.039, liquid/gas density ratios of 579-985 and Reynolds numbers of 1060-15080. Measurements included pulsed shadowgraphy and double-pulsed holography to find drop sizes and velocities after breakup. Drop size distributions after breakup satisfied Simmons' universal root normal distribution in all three breakup regimes, after removing the core (or drop-forming) drop from the drop population for shear breakup. The size and velocity of the core drop after shear breakup then was correlated successfully based on the observation that the end of drop stripping corresponded to a constant Eotvos number. The relative velocities of the drop liquid were significantly reduced during secondary breakup, due both to large drag coefficients during the drop deformation stage and reduced relaxation times of smaller drops. These effects were correlated successfully based on a simplified phenomenological theory.

  2. Projectile deformation effects in the breakup of 37Mg

    NASA Astrophysics Data System (ADS)

    Shubhchintak; Chatterjee, R.; Shyam, R.

    2016-05-01

    We study the breakup of 37Mg on Pb at 244MeV/u with the recently developed extended theory of Coulomb breakup within the postform finite range distorted wave Born approximation that includes deformation of the projectile. Comparing our calculated cross section with the available Coulomb breakup data we determine the possible ground state configuration of 37Mg.

  3. Drop breakup and deformation in sudden onset strong flows

    NASA Astrophysics Data System (ADS)

    Marks, Charles Raphael

    This work characterizes the deformation and breakup of a single drop subjected to a sudden onset shear flow. The drop is immersed in a second fluid (the matrix) with which it is immiscible. A cylindrical couette device is used to create a flow field which, in the absence of the drop, would constitute a close approximation of simple shear flow. The magnitude of the imposed shear rate was greater than that which would be necessary to just break the drop. The experiments conducted were limited to matrix fluid viscosities above 7Pa˙ s and shear rates below 15/s, ensuring that the flows considered were inertialess. The matrix fluid was a corn syrup solution. The drop fluids were polybutadiene, paraffin oil and silicone oil, leading to a range of interfacial tensions. At the shear rates used in these experiments the fluids used Newtonian. Viscosity ratios (drop/matrix) ranging from 0.01 to 1 were considered. Two breakup mechanisms were observed to contribute to the dispersion of the original drop. In all cases elongative end pinching, defined by this study, caused the ends of a stretching drop to break off and form daughter drops. Breakup due to elongative end pinching was always the first breakup observed. The daughter drops formed by elongative end pinching were always the largest daughter drops formed. In cases when the experimental conditions were sufficiently stronger than the critical conditions (needed to just barely break up the drop), a second type of breakup, capillary wave breakup, was also observed. Measurement of the characteristic time scales and length scales were made of each type of breakup. The lengths (a) were found to scale as capillary numbers: Ca=a mg/s. The times (t) were found to scale as strains: s=t g. A qualitative explanation for the capillary number scaling is presented and quantitatively compared to predictions based on small deformation analysis. Additionally the daughter drop size distributions resulting from drop breakup is characterized

  4. Drop deformation and breakup in flows with and without shear

    NASA Astrophysics Data System (ADS)

    Kékesi, Tímea; Amberg, Gustav; Prahl Wittberg, Lisa

    2015-11-01

    The deformation and breakup of liquid drops in gaseous flows are studied numerically using the Volume of Fluid method. Fragmentation of fuel drops has a key role in combustion, determining the rate of mixing and the efficiency of the process. It is common to refer to Weber number 12 as the onset of breakup, and to define breakup mode regimes as a function of Weber number. These definitions are established for simple flows and do not take density and viscosity ratios into account. The main objective of this work is the dynamics of the drop leading to breakup. Fully developed uniform flows and flows with various shear rates are considered. A Weber number of 20, Reynolds numbers 20-200, density ratios 20-80, and viscosity ratios 0.5-50 were used. Results for uniform flows are presented in Kékesi T. et al. (2014). The final aim of the project is to extend existing atomization models for fuel sprays by accounting for density and viscosity ratios in addition to the Reynolds and Weber numbers already present in current models. Estimations for the lifetime of the drop are provided; furthermore, the history of the drag coefficient is compared for several cases. Examples of the observed phenomena and ideas for possible model modifications will be presented. This work is supported by the Swedish Research Council and the Linné FLOW Centre.

  5. 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.

  6. Deformation and breakup of viscoelastic droplets in confined shear flow

    NASA Astrophysics Data System (ADS)

    Gupta, A.; Sbragaglia, M.

    2014-08-01

    The deformation and breakup of Newtonian and viscoelastic droplets are studied in confined shear flow. Our numerical approach is based on a combination of lattice-Boltzmann models and finite difference schemes, the former used to model two immiscible fluids with variable viscosity ratio and the latter used to model the polymer dynamics. The kinetics of the polymers is introduced using constitutive equations for viscoelastic fluids with finitely extensible nonlinear elastic dumbbells with Peterlin's closure. We quantify the droplet response by changing the polymer relaxation time τP, the maximum extensibility L of the polymers, and the degree of confinement, i.e., the ratio of the droplet diameter to wall separation. In unconfined shear flow, the effects of droplet viscoelasticity on the critical capillary number Cacr for breakup are moderate in all cases studied. However, in confined conditions a different behavior is observed: The critical capillary number of a viscoelastic droplet increases or decreases, depending on the maximum elongation of the polymers, the latter affecting the extensional viscosity of the polymeric solution. Force balance is monitored in the numerical simulations to validate the physical picture.

  7. Experimental constraints on the deformation and breakup of injected magma

    NASA Astrophysics Data System (ADS)

    Hodge, Kirsten F.; Carazzo, Guillaume; Jellinek, A. Mark

    2012-04-01

    The injection, breakup and stirring of dikes entering convecting silicic magma chambers can govern how they grow and differentiate, as well as influence their potential for eruption at the surface. Enclaves observed in plutons may preserve a record of this process and, thus, identifying and understanding the physical processes underlying their formation is a crucial issue in volcanology. We use laboratory experiments and scaling theory to investigate the mechanical and rheological conditions leading to the deformation and breakup of analog crystal-rich dikes injected as discrete plumes that descend into an underlying imposed shear flow. To scale the experiments and map the results across a wide range of natural conditions we define the ratio S of the timescale for the growth of a gravitational Rayleigh-Taylor (R-T) instability of the sheared, injected material to the timescale for settling through the fluid layer and the ratio Y of the timescales for shearing and lateral disaggregation of the particle-fluid mixture (yielding). At low S (< 3) and high Y (> 40), descending plumes are stretched and tilted before undergoing R-T instability, forming drips with a wavelength that is comparable to the initial diameter of the injection. At low Y (< 40) and S values that increase from ∼ 3 as Y → 0, an injection yields in tension before a R-T instability can grow, forming discrete particle-fluid blobs that are much smaller than the initial injection diameter and separated by thin filaments of the original mixture. At high S (> 3) and high Y (> 40), injections remain intact as they settle through the layer and pond at the floor. Applied to magma chambers, our results do not support the production of a continuum of enclave sizes. Indeed, from scaling analyses we expect the two breakup regimes to form distinct size populations: Whereas enclaves formed in the R-T regime will be comparable to the injection size, those formed in the tension regime will be much smaller. We show

  8. 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

  9. Deformation, wave phenomena, and breakup outcomes of round nonturbulent liquid jets in uniform gaseous crossflow

    NASA Astrophysics Data System (ADS)

    Ng, Chee-Loon

    Scope and method of study. An experimental and computational research is performed to study the deformation and breakup of round nonturbulent liquid jets in uniform gaseous crossflow. Pulsed photography and shadow graphy in conjunction with high-speed imaging were used to study the wave phenomena and the droplets properties/transport dynamics of a nonturbulent liquid jet injected into a uniform crossflow within the bag breakup regime. The computational study extended the previous two-dimensional study by adding the third dimension, allowing the wave properties to be modeled. The computational simulation employed the Volume of Fluid (VOF) formulation of FLUENT, and was run on a 3-processors parallel Linux cluster and P4 desktops. The validated, time-accurate, CFD simulation analyzes the surface properties of the liquid jets within the column, bag, and shear breakup regimes by considering the effects of surface tension, liquid viscosity, and crossflow Weber number at large liquid/gas density ratios (>500) and small Ohnesorge numbers (<0.1). Findings and conclusions. Present experimental results show that the column waves along the liquid jet are attributed to Rayleigh-Taylor instabilities and the nodes layout per bag affected the breakup mechanisms of the bags. Three distinctive sizes of droplets were produced in the bag breakup regime. The size of bag-droplets normalized by the nozzle exit diameter was constant. The different trajectories for bag- and node-droplets suggested that separation of bag- and node-droplets is possible. The computational results included jet deformations, jet cross-sectional area, jet velocity, wake velocity defect, wake width, and wavelengths of column and surface waves. Present computational results yielded a similarity solution for the inner wake region. In bag breakup, the lower pressure along the sides of the jet pulled the liquid away from both the upwind and downwind surfaces of the liquid cross-section. In shear breakup, the

  10. Deformation, breakup and motion of a perfect dielectric drop in a quadrupole electric field

    NASA Astrophysics Data System (ADS)

    Deshmukh, Shivraj. D.; Thaokar, Rochish. M.

    2012-03-01

    A detailed nonlinear analysis of the deformation and breakup of a perfect dielectric (PD) drop, suspended in another perfect dielectric fluid, in the presence of a quadrupole electric field is presented using analytical (asymptotic) and numerical (boundary integral) methods. The quadrupole field is the simplest kind of an axisymmetric non-uniform electric field. A drop, when placed at the center of such a field, does not translate, thus allowing systematic investigation of the effect of non-uniformity of the electric field. The deformation of a drop under a quadrupole field for PD-PD systems exhibits several novel features as compared to that of a drop under a uniform electric field. The first order analysis predicts oblate deformation for a PD-PD system when the dielectric constant of the suspending medium is larger than that of the drop (Q = ɛi/ɛe < 1). This is in sharp contrast to uniform electric fields where oblate shapes are observed only in leaky dielectric systems. Prolate shapes are observed for Q > 1, and the deformation is larger than that for uniform fields for similar electric capillary numbers. The steady state shapes are defined by higher harmonics as compared to the uniform field. At large capillary numbers, prolate deformations (Q > 1) show breakup whereas oblate deformations (Q < 1) do not. Positive and negative dielectrophoresis is observed when the drop is placed off center, and its translation and simultaneous deformation under quadrupole fields is also investigated. The electro-hydrostatics is unaffected by the viscosity ratio. However, the breakup of the drop and the dielectrophoretic motion and deformation strongly depend upon the viscosity ratio.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. How does the lithosphere deformation mode during continental breakup affect mantle exhumation and subsidence history?

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Mantle exhumation at magma-poor rifted continental margin requires that continental crust ruptures prior to the onset of significant decompression melting. Both the relative timing of crustal rupture and melting, and therefore mantle exhumation, and rifted margin subsidence are dependent on the deformation mode of the continental lithosphere stretching and thinning leading to breakup. Fletcher et al. (2009) showed that for the Iberia-Newfoundland rifted margin, modelling of continental lithosphere stretching and thinning by pure-shear resulted in decompression melt initiation before continental crustal-rupture, while stretching and thinning by upwelling-divergent "corner flow" resulted in crustal-rupture before melt initiation. Observations at rifted continental margins (including Iberia-Newfoundland rifted margin) suggest a complex rifting evolution that cannot be explained by simplistic end-member pure-shear or "corner flow" deformation modes of lithosphere thinning and stretching (Péron-Pinvidic and Manatschal, 2009). By analogy with the deformation processes occurring at slow spreading ocean-ridges (Cannat, 1996), a more realistic lithosphere deformation mode for magma-poor continental breakup is extensional faulting for the colder brittle upper 12-15km above upwelling-divergent "corner flow" for the remaining lithosphere and asthenosphere. We use a kinematic numerical model of continental lithosphere thinning and stretching to examine decompression melt initiation, continental crustal rupture and subsidence for such a hybrid lithosphere deformation model represented by pure-shear deformation in the topmost brittle lithosphere above upwelling-divergent flow. We explore the relative contributions of pure-shear and upwelling-divergent "corner flow" deformation and its sensitivity to deformation rate, pure-shear half-width, the "corner flow" Vz/Vx ration and mantle potential temperature. The kinematic numerical model that we use represents lithosphere and

  17. 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.

  18. 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.

  19. Deformation and breakup of liquid drops in a gas stream at nearly critical Weber numbers

    NASA Astrophysics Data System (ADS)

    Wierzba, A.

    1990-04-01

    Experimentally determined values of the critical Weber number available from the literature are scattered over a very wide range of W(e)sub c from 2.2 to 99.6. To study one possible source of these discrepancies an experimental investigation was made of the deformation and breakup of water droplets at nearly critical Weber numbers. Experiments were conducted in a small horizontal wind tunnel. A continuous stream of uniform water droplets was allowed to fall perpendicularly to the continuous stream of air. The time histories of water droplets were recorded by using a high-speed camera. Five different basic behaviors of water droplets were recorded in the range of W(e) = 11 to 14. It was found that an increase in the Weber number in this region resulted in an increased percentage of droplets with regular bag type breakup.

  20. 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.

  1. Interpretation of Coulomb breakup of Ne31 in terms of deformation

    NASA Astrophysics Data System (ADS)

    Hamamoto, Ikuko

    2010-02-01

    The recent experimental data on Coulomb breakup of the nucleus Ne31 are interpreted in terms of deformation. The measured large one-neutron removal cross section indicates that the ground state of Ne31 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- coming from either the Nilsson level [3301/2] or the Nilsson level [3213/2] depending on the neutron separation energy Sn. However, the possibility of 1/2+ coming from [2001/2] is not excluded. It is suggested that if the large ambiguity in the measured value of Sn of Ne31, 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. Electrolytic drops in an electric field: A numerical study of drop deformation and breakup.

    PubMed

    Pillai, R; Berry, J D; Harvie, D J E; Davidson, M R

    2015-07-01

    The deformation and breakup of an axisymmetric, conducting drop suspended in a nonconducting medium and subjected to an external electric field is numerically investigated here using an electrokinetic model. This model uses a combined level set-volume of fluid formulation of the deformable surfaces, along with a multiphase implementation of the Nernst-Planck equation for transport of ions, that allows for varying conductivity inside the drop. A phase diagram, based on a parametric study, is used to characterize the stability conditions. Stable drops with lower ion concentration are characterized by longer drop shapes than those achieved at higher ion concentrations. For higher drop ion concentration, greater charge accumulation is observed at drop tips. Consequently, such drops break up by pinching off rather than tip streaming. The charge contained in droplets released from unstable drops is shown to increase with drop ion concentration. These dynamic drop behaviors depend on the strength of the electric field and the concentration of ions in the drop and result from the interplay between the electric forces arising from the permittivity jump at the drop interface and the ions in the bulk. PMID:26274270

  3. 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

  4. Field and experimental constraints on the deformation and break-up up of injected magma (Invited)

    NASA Astrophysics Data System (ADS)

    Hodge, K. F.; Carazzo, G.; Jellinek, M.

    2010-12-01

    ), the injected tube is too stiff and does not go unstable or breakup. Initial field observations of migrating tubes (Paterson 2009) in the TIS suggest that the break-up of these features can be linked to the yield strength of the magma during deformation. Here, we present a field investigation that includes detailed mapping of ~100 migrating tubes in the Cathedral Peak Granite (along with some tubes in the Half Dome granite). Preliminary results suggest that a few long tubes appear to have been broken up into regularly spaced sections. Interestingly, the majority of the mapped tubes (specifically where they occur in large clusters) are located near a contact with either host rock or another intrusive unit in the TIS and are oriented roughly perpendicular to that contact. The preserved length scales of deformation are compared to experimental regimes in which tubes break up into blobs.

  5. 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

  6. 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

  7. 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

  8. Finite element method for a class of viscoelastic flows in deforming domains applied to jet breakup

    NASA Astrophysics Data System (ADS)

    Keunings, R.

    1984-05-01

    A numerical method for solving a class of transient viscoelastic flows in domains with free boundaries which is based on a Galerkin finite element technique combined with a predictor/corrector scheme that allows for the prediction of stress field, velocity field and flow domain as a function of time is presented. The numerical procedure is applied to the analysis of surface tension driven breakup of liquid jets. The nonlinear growth of a periodic disturbance imposed on an infinitely long jet and leading to breakup was studied. It is predicted that in the Newtonian case the birth of satellite drops when inertia forces are present. It is shown that elasticity accelerates the breakup process at short times for an Oldroyd fluid which is consistent with linear stability analyses. This tendency however, is reversed at later times when a pattern of drops connected by stable filaments is obtained. The stabilizing effect of elastic forces, known experimentally for any years, and are predicted shown it is that the breakup mechanism of a viscoelastic jet cannot be described by linearized dynamics.

  9. Finite element method for a class of viscoelastic flows in deforming domains applied to jet breakup

    SciTech Connect

    Keunings, R.

    1984-05-01

    A numerical method for solving a class of transient viscoelastic flows in domains with free boundaries is based on a Galerkin/Finite Element technique combined with a predictor-corrector scheme that allows for the prediction of stress field, velocity field and flow domain as a function of time. The numerical procedure is applied to the analysis of surface-tension-driven breakup of liquid jets. We study the nonlinear growth of a periodic disturbance imposed on an infinitely long jet and leading to breakup. In the Newtonian case, we predict the birth of satellite drops when inertia forces are present. Results for an Oldroyd fluid show that elasticity accelerates the breakup process at short times which is consistent with linear stability analyses. However, this tendency is dramatically reversed at later times when a pattern of drops connected by remarkably stable filaments is obtained. We thus predict the stabilizing effect of elastic forces, known experimentally for many years, and show that the breakup mechanism of a viscoelastic jet cannot be described by linearized dynamics.

  10. 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.

  11. 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.

  12. Observation of the spread of slow deformation in Greece following the breakup of the slab

    NASA Astrophysics Data System (ADS)

    Durand, Virginie; Bouchon, Michel; Floyd, Michael A.; Theodulidis, Nikos; Marsan, David; Karabulut, Hayrullah; Schmittbuhl, Jean

    2014-10-01

    Over the past two decades, geophysical observations have shown that earthquakes can trigger other earthquakes, raising the possibility that earthquake interaction plays an important role in the earth's deformation. We analyze here a "storm" of earthquakes in Greece and show that their interaction provides remarkable insight into the mechanics of one of the fastest deforming continental region in the world. A rupture of the African slab initiates a cascade of large earthquakes and a long episode of slow slip marking the downward plunge of the slab, the concomitant rollback of the subduction, and the subsequent detachment of southern Greece from the Eurasian plate. Intense crustal deformation, indicative of the resulting plate stretching, follows. This slow deformation which spreads in a few months over more than 500 km lasts ~3 years and triggers earthquakes. The observations also show that the retreat of the African subduction is the motor of the Aegean deformation.

  13. 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.

  14. Effect of surface alignment layer and polymer network on the Helfrich deformation in cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Nemati, H.; Yang, D.-K.; Cheng, K.-L.; Liang, C.-C.; Shiu, J.-W.; Tsai, C.-C.; Zola, R. S.

    2012-12-01

    We show that the Helfrich deformation can be used for fast response time, low driving voltage reflective displays by using cholesteric liquid crystals under short voltage pulses (˜10 ms). Rather than turning planar domains into focal conic domains through a nucleation process, as used in bistable modes, the fast voltage pulse only deforms the cholesteric planar layers to form wrinkled layers. Since the deformed state is formed through a homogeneous process, quick response times and low operating voltage can be achieved. We studied the effects of alignment layer and dispersed polymer on the stability of the Helfrich deformed cholesteric layers, and found that homogeneous alignment layer and polymer network can inhibit the nucleation process responsible for breaking the layers.

  15. 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

  16. Experimental validation of a numerical model for predicting the trajectory of blood drops in typical crime scene conditions, including droplet deformation and breakup, with a study of the effect of indoor air currents and wind on typical spatter drop trajectories.

    PubMed

    Kabaliuk, N; Jermy, M C; Williams, E; Laber, T L; Taylor, M C

    2014-12-01

    Bloodstain Pattern Analysis (BPA) provides information about events during an assault, e.g. location of participants, weapon type and number of blows. To extract the maximum information from spatter stains, the size, velocity and direction of the drop that produces each stain, and forces acting during flight, must be known. A numerical scheme for accurate modeling of blood drop flight, in typical crime scene conditions, including droplet oscillation, deformation and in-flight disintegration, was developed and validated against analytical and experimental data including passive blood drop oscillations, deformation at terminal velocity, cast-off and impact drop deformation and breakup features. 4th order Runge-Kutta timestepping was used with the Taylor Analogy Breakup (TAB) model and Pilch and Erdman's (1987) expression for breakup time. Experimental data for terminal velocities, oscillations, and deformation was obtained via digital high-speed imaging. A single model was found to describe drop behavior accurately in passive, cast off and impact scenarios. Terminal velocities of typical passive drops falling up to 8m, distances and times required to reach them were predicted within 5%. Initial oscillations of passive blood drops with diameters of 1mmdeformation. Blood drops with diameter 0.4-4mm and velocity 1-15m/s cast-off from a rotating disk showed low deformation levels (Weber number<3). Drops formed by blunt impact 0.1-2mm in diameter at velocities of 14-25m/s were highly deformed (aspect ratios down to 0.4) and the larger impact blood drops (∼1-1.5mm in diameter) broke up at critical Weber numbers of 12-14. Most break-ups occurred within 10-20cm of the impact point. The model predicted deformation

  17. 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…

  18. 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

  19. 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.

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

    PubMed

    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 50μm, 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. PMID:26764706

  1. 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

  2. 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.

  3. Satellite Breakup Risk Mitigation

    NASA Technical Reports Server (NTRS)

    Leleux, Darrin P.; Smith, Jason T.

    2006-01-01

    Many satellite breakups occur as a result of an explosion of stored energy on-board spacecraft or rocket-bodies. These breakups generate a cloud of tens or possibly hundreds of thousands of debris fragments which may pose a transient elevated threat to spaceflight crews and vehicles. Satellite breakups pose a unique threat because the majority of the debris fragments are too small to be tracked from the ground. The United States Human Spaceflight Program is currently implementing a risk mitigation strategy that includes modeling breakup events, establishing action thresholds, and prescribing corresponding mitigation actions in response to satellite breakups.

  4. 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

  5. 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.

  6. Treatment of chronic low back pain in patients with spinal deformities using a sagittal re-alignment brace

    PubMed Central

    Weiss, Hans-Rudolf; Werkmann, Mario

    2009-01-01

    Background For adult scoliosis patients with chronic low back pain bracing is initially indicated before spinal surgery is considered. Until recently there has been a lack of research into the effect upon pain reductions in the mid and long-term. Promising results have been documented in short-term studies for the application of a sagittal re-alignment brace in patients with spinal deformities and along with pain; however mid-term and long-term results are not yet available. The purpose of this study is to investigate the mid-term effects of this brace with respect to pain control. Materials and methods 67 patients (58 females and 9 males) with chronic low back pain (> 24 months) and the diagnosis of scoliosis or hyperkyphosis were treated with a sagittal re-alignment brace (physio-logic brace™) between January 2006 and July 2007. The indication for this kind of brace treatment was derived from a positive sagittal re-alignment test (SRT) and the exclusion of successful conservative treatment during the last 24 months. The aim of this type of conservative intervention was to avoid surgery for chronic low back pain. Results The average pain intensity was measured on the Roland and Morris VRS (5 steps) before treatment. This was 3.3 (t1), at the time of brace adjustment it was 2.7 (t2) and after at an average observation time of 18 months it was 2.0 (t3). The differences were highly significant in the Wilcoxon test. Discussion Short-term measurements showed that a significant pain reduction is possible in chronic postural low back pain using a sagittal re-alignment brace inducing lumbar re-lordosation. In a preliminary report at adjustment (t2), highly significant improvements of pain intensity have also been demonstrated. At 6 months of treatment however, no improvement was measured. The improvement of the mid-term effects (18 months) found in this study compared to the preliminary report may be due to the changed approach to compliance: whilst the bracing standard

  7. Atmospheric breakup of meteoroids

    NASA Astrophysics Data System (ADS)

    El-Dasher, Bassem; Swift, Damian; Remington, Bruce; Mulford, Roberta; Milathianaki, Despina; Chen, Laura; Eakins, Daniel

    2013-06-01

    When meteoroids enter a planetary atmosphere, breakup is governed by the Rayleigh-Taylor instability, mitigated by the strength of the meteoritic material. Particle sizes in the breakup cascade depend on the perturbation length scales exhibiting growth. The physics of meteoroid entry is thus related closely to experiments where strength at high pressure is inferred from the Rayleigh-Taylor growth of perturbations. There are significant discrepancies between predicted and observed breakup altitudes of meteoroids, which in turn reduce the accuracy of assessments of the impact threat from asteroids. Simulations, validated by laboratory experiments of instability growth, can play a role in understanding the breakup of meteoroids and thus the threat from asteroids. Continuum dynamics simulations provide more rigorous stress distribution than are usually used in breakup analyses, and can be used to calibrate compact expressions describing the breakup conditions. We have measured the strength of samples from Fe-rich meteorites using indentation and shock-loading experiments, and found them to be significantly stronger than was previously realized. This, together with the more accurate stress analysis, removes the altitude discrepancy for Fe-rich meteorites. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Photo-Induced Anomalous Deformation of Poly(N-Isopropylacrylamide) Gel Hybridized with an Inorganic Nanosheet Liquid Crystal Aligned by Electric Field.

    PubMed

    Inadomi, Takumi; Ikeda, Shogo; Okumura, Yasushi; Kikuchi, Hirotsugu; Miyamoto, Nobuyoshi

    2014-09-16

    Poly-(N-isopropylacrylamide) (PNIPA) hydrogel films doped with uniaxially aligned liquid crystalline (LC) nanosheets adsorbed with a dye are synthesized and its anomalous photothermal deformation is demonstrated. The alignment of the nanosheet LC at the cm-scale is easily achieved by the application of an in-plane or out-of-plane AC electric field during photo-polymerization. A photoresponsive pattern is printable onto the gel with μm-scale resolution by adsorption of the dye through a pattern-holed silicone rubber. When the gel is irradiated with light, only the colored part is photothermally deformed. Interestingly, the photo-irradiated gel shows temporal expansion along one direction followed by anisotropic shrinkage, which is an anomalous behavior for a conventional PNIPA gel. PMID:25228493

  9. 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.

  10. Coulomb Breakup Problem

    SciTech Connect

    Kadyrov, A. S.; Bray, I.; Stelbovics, A. T.; Mukhamedzhanov, A. M.

    2008-12-05

    We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the three-body wave functions. This formulation is valid for both short-range and Coulombic potentials. The post and prior forms of the breakup amplitude are derived without any reference to renormalization procedures.

  11. 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.

  12. 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

  13. Air induced breakup of drops.

    NASA Astrophysics Data System (ADS)

    Han, Jaehoon; Tryggvason, Gretar

    1997-11-01

    The deformation and breakup of drops subject to both sudden and gradual acceleration is examined by axisymmetric inviscid and full numerical simulations. In the full simulations, the Navier Stokes equations are solved for the fluid inside and outside of the drop by a Front Tracking/Finite Difference Method. In the limit of small density stratification, inviscid simulations show the formation of a toroidal drop for small surface tension and the formation of skirts as the surface tension is increased. The viscous computations show a similar transition plus a RbagS break up for a relatively high surface tension, but not high enough so that the drop reaches a steady state deformation. The RbagS break up mode appears when the drop slows down due to viscous dissipation after most of its fluid has accumulated in the rim, forming a torous connected by a thin film. A RbagS is formed when the rim starts to fall faster than the film. The various break up modes, as a function of the Ohnesorge and Weber (or Eotvos) numbers as well as property ratios is discussed. Supported by AFOSR.

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

    PubMed Central

    Morishita, Yoshihiro; Kuroiwa, Atsushi; Suzuki, Takayuki

    2015-01-01

    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. PMID:25858459

  15. An auroral breakup mechanism

    NASA Technical Reports Server (NTRS)

    Maggs, J. E.

    1973-01-01

    A purely growing electrostatic drift instability driven by the electron temperature gradient at the inner edge of the plasma sheet can grow for large enough values of the temperature gradient. The parallel electric field associated with the instability is localized near the magnetic equator. The growth of the drift instability leads to enhanced whistler noise and increased electron pitch angle diffusion. If the current limit is exceeded in the ionosphere while the parallel electric field of the drift instability exists along the field line, rapid electron precipitation (the auroral breakup) can result.

  16. Development of a droplet breakup model considering aerodynamic and droplet collision effects

    NASA Technical Reports Server (NTRS)

    Wert, K. L.; Jacobs, H. R.

    1993-01-01

    A model is currently under development to predict the occurrence and outcome of spray droplet breakup induced by aerodynamic forces and droplet collisions. It is speculated that these phenomena may be significant in determining the droplet size distribution in a spray subjected to acoustic velocity fluctuations. The goal is to integrate this breakup model into a larger spray model in order to examine the effects of combustion instabilities on liquid rocket motor fuel sprays. The model is composed of three fundamental components: a dynamic equation governing the deformation of the droplet, a criterion for breakage based on the amount of deformation energy stored in the droplet and an energy balance based equation to predict the Sauter mean diameter of the fragments resulting from breakup. Comparison with published data for aerodynamic breakup indicates good agreement in terms of predicting the occurrence of breakup. However, the model significantly over predicts the size of the resulting fragments. This portion of the model is still under development.

  17. Development of a droplet breakup model considering aerodynamic and droplet collision effects

    NASA Astrophysics Data System (ADS)

    Wert, K. L.; Jacobs, H. R.

    1993-11-01

    A model is currently under development to predict the occurrence and outcome of spray droplet breakup induced by aerodynamic forces and droplet collisions. It is speculated that these phenomena may be significant in determining the droplet size distribution in a spray subjected to acoustic velocity fluctuations. The goal is to integrate this breakup model into a larger spray model in order to examine the effects of combustion instabilities on liquid rocket motor fuel sprays. The model is composed of three fundamental components: a dynamic equation governing the deformation of the droplet, a criterion for breakage based on the amount of deformation energy stored in the droplet and an energy balance based equation to predict the Sauter mean diameter of the fragments resulting from breakup. Comparison with published data for aerodynamic breakup indicates good agreement in terms of predicting the occurrence of breakup. However, the model significantly over predicts the size of the resulting fragments. This portion of the model is still under development.

  18. 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).

  19. Spontaneous Periodic Deformations in Nonchiral Planar-Aligned Bimesogens with a Nematic-Nematic Transition and a Negative Elastic Constant

    NASA Astrophysics Data System (ADS)

    Panov, V. P.; Nagaraj, M.; Vij, J. K.; Panarin, Yu. P.; Kohlmeier, A.; Tamba, M. G.; Lewis, R. A.; Mehl, G. H.

    2010-10-01

    Hydrocarbon linked mesogenic dimers are found to exhibit an additional nematic phase below the conventional uniaxial nematic phase as confirmed by x-ray diffraction. The phase produces unusual periodic stripe domains in planar cells. The stripes are found to be parallel to the rubbing direction (in rubbed cells) with a well-defined period equal to double the cell gap. The stripes appear without external electromagnetic field, temperature or thickness gradients, rubbing or hybrid alignment treatments. Simple modeling proposes a negative sign for at least one of the two elastic constants: splay and twist, as a necessary condition for the observed pattern.

  20. 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

  1. The role of magnetic flux tube deformation and magnetosheath plasma beta in the saturation of the Region 1 field-aligned current system

    NASA Astrophysics Data System (ADS)

    Wilder, F. D.; Eriksson, S.; Wiltberger, M.

    2015-03-01

    The phenomena of cross polar cap potential (CPCP) and ionospheric field-aligned current (FAC) saturation remain largely unexplained. In the present study, we expand upon the Alfvén wing model of CPCP saturation by investigating its impact on the magnetosphere-ionosphere current system, particularly the Region 1 FAC input into the polar cap. Our hypothesis is that the ability of open flux tubes to deform in response to applied fluid stress from the magnetosheath is governed by the magnetosheath plasma beta, which in turn governs the Maxwell stress imposed on ionospheric plasma from the magnetosphere. We performed 32 MHD simulations with varying solar wind density and interplanetary magnetic field strength and show that the plasma beta does govern the deformation of open field lines, as well as the nonlinear response of the Region 1 FAC system to increasingly southward interplanetary magnetic field. Further, we show that the current-voltage relationship in the ionosphere also shows a dependence on the plasma beta in the magnetosheath, with the ionosphere becoming more resistive at lower beta.

  2. The Role of Polar Cap Flux Tube Deformation and Magnetosheath Plasma Beta in the Saturation of the Region 1 Field-Aligned Current System

    NASA Astrophysics Data System (ADS)

    Wilder, F. D.; Eriksson, S.; Wiltberger, M. J.

    2014-12-01

    The phenomena of cross-polar cap potential (CPCP) and ionospheric field-aligned current (FAC) saturation remains largely unexplained. In this study, we expand upon the Alfvén Wing model of CPCP saturation by investigating its impact on the magnetosphere-ionosphere current system, particularly the Region 1 FAC input into the polar cap. Our hypothesis is that the ability of open flux tubes to deform in response to applied fluid stress from the magnetosheath is governed by the magnetosheath plasma beta, which in turn governs the Maxwell stress imposed on ionospheric plasma from the magnetosphere. This leads both the Region 1 FAC input as well as the ionospheric convection strength, as represented by the CPCP, to saturate in response to the interplanetary magnetic field (IMF) driving. We perform 32 simulations using the Lyon-Fedder-Mobarry (LFM) Magnetohydrodynamic (MHD) model with varying solar wind density and IMF strength, and demonstrate that the plasma beta does govern the deformation of polar cap and lobe field lines, as well as the non-linear response of the Region 1 FAC system to increasingly southward IMF. Further, we show that the current-voltage relationship in the ionosphere also shows a dependence on the plasma beta in the magnetosheath, with the ionosphere becoming more resistive at lower beta.

  3. 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.

  4. Experimental study of submillimeter droplets dynamics and breakup in continuous supersonic flow terminated by shock wave

    NASA Astrophysics Data System (ADS)

    Gobyzov, Oleg; Lozhkin, Yuriy; Ryabov, Mikhail; Markovich, Dmitriy

    2016-03-01

    The present paper reports an application of optical methods, namely PIV, background-oriented-schlieren (BOS) and high-magnification imaging with background illumination to study of dynamics and breakup of 10-100 μm size droplets in continuous supersonic flow terminated by a normal shock wave. Flow diagnostics was performed by means of BOS and PIV. Shadow photography allowed to specify velocity ranges for different droplet sizes and to visualize droplets dynamics and breakup modes. Features of the experimental setup and certain details of implemented measurement system are considered. Results of velocity measurements and droplets behavior, including deformation and breakup, are presented and analysis of experimental conditions and dimensionless parameters affecting the droplets behavior is performed. Distinctive features of deformation and breakup processes of submillimeter scale droplets are revealed.

  5. 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. PMID:26159802

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Collision, Coalescence and Breakup of Raindrops. Part I: Experimentally Established Coalescence Efficiencies and Fragment Size Distributions in Breakup.

    NASA Astrophysics Data System (ADS)

    Low, T. B.; List, Roland

    1982-07-01

    The collision, coalescence and breakup of single raindrop pairs were studied at terminal velocities and laboratory pressure (100 kPa) in 761 collision experiments (out of 14 000 attempts). Six size combinations were used with drop pair diameters of [0.18;.0.0395 cm], [0.40; 0.0395 cm], [0.44; 0.0395 cm], [0.18; 0.0715 cm], [0.18; 0.10 cm] and [0.30; 0.10 cm]. For averaging purposes the experiments were repeated over one hundred times for each pair.The new coalescence efficiencies and fragment size distributions in breakup turned out to be consistent with those of McTaggart-Cowan and List (1975b) and permitted the combination of the two data sets into a single data bank spanning essentially the entire range of raindrop sizes.The analysis addressed three main geometric shapes formed by the drops after initial contact, namely, filaments, sheets and disks, and the fragment size distributions after breakup. Significant collisional growth, i.e., coalescence, occurred only when drops <0.06 cm in diameter were struck by larger ones. An empirical equation involving collision kinetic (CKE) and surface tension energies was developed to approximate the observed coalescence efficiencies.Breakup fragment size distributions normally show two or three peaks, one close to the size of the large drop of the collision pair, one at times (for filaments) reflecting the small drop, and the third centered at sizes below the small drop diameter. At high energy collisions involving larger drops the mechanism most favorable for coalescence was the disk shape because with its high deformation it is able to dissipate the most energy either through air drag or by internal viscosity through oscillations. The lowest collision energy for breakup is required for filaments; more is needed for sheets and most for disks.

  11. Beam breakup calculations for the second axis of DARHT

    SciTech Connect

    Fawley, William M.; Chen, Y.-J.; Houck, T.L.

    1999-08-20

    The accelerator for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) facility will produce a 4-kA, 20-MeV, 2-{micro}s output electron beam with a design goal of less than 1000 {pi} mm-mrad normalized transverse emittance and less than 0.5-mm beam centroid motion. In order to meet this goal, the beam transport must have excellent optics and the beam breakup instability (BBU) must be limited in growth. Using a number of simulation codes such as AMOS and BREAKUP, we have modeled the transverse impedances of the DARHT-II accelerator cells and the electron beam response to different transverse excitations such as injector RF noise, magnetic dipole fields arising from the 90-degree bend between the cathode stalk and insulator column, and downstream solenoid alignment errors. The very low Q ({approx}2) predicted for the most important TM dipole modes has prompted us to extend the BREAKUP code to be able to use the dipole wakefields calculated by AMOS in addition to the most usual discrete frequency BBU mode model. We present results for the predicted BBU growth and the empirical sensitivity to various machine parameters.

  12. Orbital debris from upper-stage breakup

    NASA Technical Reports Server (NTRS)

    Loftus, Joseph P., Jr. (Editor)

    1989-01-01

    The present conference on the effects of launch vehicle upper-stage breakup on the orbital debris scenario discusses an analysis of the SPOT 1 Ariane third stage, the explosive fragmentation of orbiting propellant tanks, albedo estimates for debris, Ariane-related debris in deep-space orbit, and the relationship of hypervelocity impacts to upper-stage breakups. Also discussed are the prospects for and the economics of the future removal of orbital debris, collision probabilities in GEO, current operational practices for Delta second stage breakup prevention, breakup-precluding modifications to the Ariane third stage, and the safing of the H-1 second stage after spacecraft separation.

  13. The Breakup of Water Cylinders Behind Normal Shocks

    NASA Astrophysics Data System (ADS)

    Meng, J. C.; Colonius, T.

    2012-11-01

    We simulate the drift and breakup of a water cylinder in the flow behind a normal shock. The unsteady Euler equations, closed using the stiffened-gas equation of state, are solved with a compressible, multicomponent, shock- and interface-capturing algorithm. The effects of surface tension and viscosity are negligible at early times compared to the larger shear forces. Computed drift velocities are in good agreement with experiments. For the high- speed flow regimes considered, the breakup mode is stripping. Pressure gradients arise on the cylinder's surface causing it to deform laterally. As the cylinder is flattened, sheets of liquid are drawn off the periphery and break up further downstream. Unsteady vortex shedding is observed in the wake of the disintegrating cylinder. As the shock Mach number is increased, higher airflow velocities result in faster breakup and greater cylinder accelerations. These accelerations are subject to fluctuations that grow with shock strength. Qualitative features of the flow are compared to images from experiments on cylinders and drops.

  14. Coalescence and breakup of large droplets in turbulent channel flow

    NASA Astrophysics Data System (ADS)

    Scarbolo, Luca; Bianco, Federico; Soldati, Alfredo

    2015-07-01

    Coalescence and breakup of large deformable droplets dispersed in a wall-bounded turbulent flow are investigated. Droplets much larger than the Kolmogorov length scale and characterized by a broad range of surface tension values are considered. The turbulent field is a channel flow computed with pseudo-spectral direct numerical simulations, while phase interactions are described with a phase field model. Within this physically consistent framework, the motion of the interfaces, the capillary effects, and the complex topological changes experienced by the droplets are simulated in detail. An oil-water emulsion is mimicked: the fluids are considered of same density and viscosity for a range of plausible values of surface tension, resulting in a simplified system that sets a benchmark for further analysis. In the present conditions, the Weber number (We), that is, the ratio between inertia and surface tension, is a primary factor for determining the droplets coalescence rate and the occurrence of breakups. Depending on the value of We, two different regimes are observed: when We is smaller than a threshold value (We < 1 in our simulations), coalescence dominates until droplet-droplet interactions are prevented by geometric separation; when We is larger than the threshold value (We > 1), a permanent dynamic equilibrium between coalescence and breakup events is established.

  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. Beam breakup in superconducting recirculating linacs

    SciTech Connect

    Joseph J. Bisognano

    1988-05-01

    The performance and operational flexibility of superconducting recirculating linacs can be limited by a variety of collective phenomena which are grouped under the name beam breakup. In this note the various beam breakup phenomena found in recirculating superconducting radio frequency linacs are described and appraised relative to beam performance.

  18. 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.

  19. Droplet Breakup in Expansion-contraction Microchannels.

    PubMed

    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

  20. 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

  1. 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.

  2. 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…

  3. 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…

  4. Electrostatic breakup in a misty plasma.

    PubMed

    Coppins, M

    2010-02-12

    A misty plasma is defined as a plasma containing small liquid droplets. In such a system, the droplets will undergo total electrostatic breakup if their charge exceeds the well-known Rayleigh limit. This imposes a minimum size on the droplets. Electrostatic breakup is a significant mechanism limiting droplet survival in a wide range of plasma applications, including plasma-enhanced chemical vapor deposition and fusion tokamaks. PMID:20366826

  5. Electrostatic Breakup in a Misty Plasma

    SciTech Connect

    Coppins, M.

    2010-02-12

    A misty plasma is defined as a plasma containing small liquid droplets. In such a system, the droplets will undergo total electrostatic breakup if their charge exceeds the well-known Rayleigh limit. This imposes a minimum size on the droplets. Electrostatic breakup is a significant mechanism limiting droplet survival in a wide range of plasma applications, including plasma-enhanced chemical vapor deposition and fusion tokamaks.

  6. Supercontinent Breakup and the Deep Earth

    NASA Astrophysics Data System (ADS)

    Torsvik, T. H.

    2014-12-01

    As many as five supercontinents have been proposed and the deep Earth probably holds the key to understand their breakup. The African and Pacific large low shear-wave velocity provinces (LLSVPs) have been stable for the entire Phanerozoic and possibly much longer. Their edges are the dominant source of deep plumes which travel from the base of the mantle to the surface where episodic large igneous province (LIP) activity has punctuated plate tectonics by creating and modifying plate boundaries. Pangea, the best-documented supercontinent, formed at the end of the Carboniferous (320 Ma) by fusing Gondwana and Laurussia. The Panjal Traps (289 Ma) probably assisted in an early Pangea breakup phase (opening of the Neotethys) but the most important phase of breakup started when the Central Atlantic Ocean opened at around 195 Ma. Perhaps not coincidentally, the region where the Atlantic spreading started was preceded by the emplacement of the Central Atlantic Magmatic Province (201 Ma), one of the largest LIPs. The Karoo LIP (183 Ma) heralded the Jurassic breakup of Pangea (separation of East and West Gondwana) whereas Paraná-Etendeka LIP activity (134 Ma) preceded South Atlantic break-up by a few million years. The North Atlantic realm experienced prolonged Late Palaeozoic to Cenozoic extension and sedimentary basin formation but the final Early Eocene break-up occurred shortly after a massive episode of volcanism and LIP formation (North Atlantic Igneous Province, 62 Ma) as in most Pangea breakup examples. All LIPs assisting Pangea breakup were sourced by plumes from the margin of the African LLSVP.

  7. 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.

  8. Final Rifting and Continental Breakup in the South China Sea

    NASA Astrophysics Data System (ADS)

    Franke, D.; Savva, D.; Pubellier, M. F.; Steuer, S.; Mouly, B.; Auxietre, J. L.; Meresse, F.; Chamot-Rooke, N. R. A.

    2014-12-01

    The magma-poor or intermediate magmatic South China Sea basin shows a triangular shape with a SW pointing apex, which manifests a preceding propagating rift. The earliest phase of rifting started in the Early Paleocene when a Mesozoic convergent margin changed to extension. After about 30 Myrs of rifting, breakup in the major eastern subbasin of the SCS occurred in the Early Oligocene and subsequent breakup of the southwest subbasin took place in the Late Oligocene. Seismic reflection data imaging conjugate crustal sections result in a conceptual model for rift-evolution at conjugate margins in time and space. Distinct are regular undulations in the crust-mantle boundary. Individual rift basins are bounded to crustal blocks by listric normal faults on either side. Moho uplifts are distinct beneath major rift basins, while the Moho is downbended beneath crustal blocks. Most of the basin-bounding faults sole out within the middle crust. At the distal margins, detachment faults are located at a mid-crustal level where a weak zone decouples crust and mantle lithosphere during rifting. The lower crust in contrast is interpreted as being strong. Only in the region within about 50 km from the oceanic domain we suggest that normal faults reach the mantle, enabling potentially a coupling between the crust and the mantle. Here, at the proximal margins detachment fault dip either seaward or landward. Largely symmetric structures result from the initial rifting stage. At the future breakup position either of the rift basin bounding faults subsequently penetrates the entire crust, resulting in asymmetry at this location. However, asymmetric deformation which is controlled by large scale detachment faulting is confined to narrow areas and does not result in a margin-wide simple-shear model. Rather considerable along-margin variations are suggested resulting in alternating "upper and lower plate" margins.

  9. The condition of the resonant break-up of a gas bubble subjected to an acoustic wave in liquid

    NASA Astrophysics Data System (ADS)

    Vanovskiy, V. V.; Petrov, A. G.

    2015-12-01

    The problem of a gas bubble break-up in liquid is considered in the conditions of the frequencies resonance of the radial and nth axially symmetric deformational mode 2:1. The nonlinear energy transfer between the modes is described using an efficient Krylov-Bogolyubov averaging technique. It is shown that the deformational mode magnitude can be some orders larger than the radial mode magnitude which is damped by the thermal, viscous and acoustic dissipation. The estimative criterion of bubble break-up is obtained in the cases of slow and fast acoustic wave start. The obtained pressure magnitudes in the wave for break-up are very small and the mechanism can have strong medical and technical applications.

  10. 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.

  11. 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).

  12. Development of orbital debris spacecraft breakup models

    NASA Astrophysics Data System (ADS)

    Tedeschi, William J.; Connell, John C.; McKnight, Darren S.

    1991-08-01

    The Defense Nuclear Agency has initiated an Orbital Debris Spacecraft Breakup Modeling Program to improve the accuracy and usefulness of satellite breakup models with an emphasis on collision-induced events. Empirical, semianalytic, and complex approaches are used in the modeling. Current results from the modeling effort are presented and discussed along with data from associated hypervelocity impact test programs. It is shown that major improvements in modeling have been made but that milestones must be achieved before the models will routinely provide accurate predictions for a wide range of collision scenarios.

  13. Renormalization for breakup of invariant tori

    NASA Astrophysics Data System (ADS)

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

    2005-01-01

    We present renormalization group operators for the breakup of invariant tori with winding numbers that are quadratic irrationals. We find the simple fixed points of these operators and interpret the map pairs with critical invariant tori as critical fixed points. Coordinate transformations on the space of maps relate these fixed points, and also induce conjugacies between the corresponding operators.

  14. 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.

  15. Computational modelling of microfluidic capillary breakup phenomena

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Sprittles, James; Oliver, Jim

    2013-11-01

    Capillary breakup phenomena occur in microfluidic flows when liquid volumes divide. The fundamental process of breakup is a key factor in the functioning of a number of microfluidic devices such as 3D-Printers or Lab-on-Chip biomedical technologies. It is well known that the conventional model of breakup is singular as pinch-off is approached, but, despite this, theoretical predictions of the global flow on the millimetre-scale appear to agree well with experimental data, at least until the topological change. However, as one approaches smaller scales, where interfacial effects become more dominant, it is likely that such unphysical singularities will influence the global dynamics of the drop formation process. In this talk we develop a computational framework based on the finite element method capable of resolving diverse spatio-temporal scales for the axisymmetric breakup of a liquid jet, so that the pinch-off dynamics can be accurately captured. As well as the conventional model, we discuss the application of the interface formation model to this problem, which allows the pinch-off to be resolved singularity-free, and has already been shown to produce improved flow predictions for related ``singular'' capillary flows.

  16. 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.

  17. 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

  18. 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.

  19. 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. PMID:12626269

  20. Influence of surfactant on the drop bag breakup in a continuous air jet stream

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    The deformation and breakup of surfactant-laden drops is a common phenomenon in nature and numerous practical applications. We investigate influence of surfactant on the drop bag breakup in a continuous air jet stream. The airflow would induce the advection diffusion of surfactant between interface and bulk of drop. Experiments indicate that the convective motions of deforming drop would induce the non-equilibrium distribution of surfactant, which leads to the change of surface tension. When the surfactant concentration is smaller than critical micelle concentration (CMC), with the increase of surface area of drop, the surface tension of liquid-air interface and the critical Weber number will increase. When the surfactant concentration is bigger than CMC, the micelle can be considered as the source term, which can supply the monomers. So in the presence of surfactant, there would be the significant nonlinear variation on the critical Weber number of bag breakup. We build the dynamic non-monotonic relationship between concentrations of surfactant and critical Weber number theoretically. In the range of parameters studied, the experimental results are consistent with the model estimates.

  1. Rifting and breakup in the South China Sea

    NASA Astrophysics Data System (ADS)

    Franke, Dieter; Savva, Dimitri; Pubellier, Manuel; Steuer, Stephan; Mouly, Benoit; Auxietre, Jean-Luc; Meresse, Florian; Chamot-Rooke, Nicolas

    2014-05-01

    The magma-poor or intermediate magmatic South China Sea is a natural laboratory for studying rifting and breakup. The basin shows an irregular triangular shape with a SW pointing apex, which manifests a preceding propagating rift. The earliest phase of rifting started in the Early Paleocene when a Mesozoic convergent margin changed to extension. After about 30 Million years of rifting, breakup in the major eastern subbasin of the SCS occurred in the Early Oligocene but rifting continued and subsequent breakup of the southwest subbasin took place in the Late Oligocene. The wide Early Cenozoic South China Sea rift preserves the initial rift architecture at the distal margins. Seismic reflection data imaging conjugate crustal sections at the South China Sea margins result in a conceptual model for rift-evolution at conjugate magma-poor margins in time and space. Most distinct are regular undulations in the crust-mantle boundary. Individual rift basins are bounded to crustal blocks by listric normal faults on either side. Moho uplifts are distinct beneath major rift basins, while the Moho is downbended beneath crustal blocks, with a wavelength of undulations in the crust-mantle boundary that approximately equals the thickness of the continental crust. Most of the basin-bounding faults sole out within the middle crust. At the distal margins, detachment faults are located at a mid-crustal level where a weak zone decouples crust and mantle lithosphere during rifting. The lower crust in contrast is interpreted as being strong. Only in the region within about 50 km from the continent-ocean transition (COT) we suggest that normal faults reach the mantle, enabling potentially a coupling between the crust and the mantle. Here, at the proximal margins detachment fault dip either seaward or landward. This may indicate the presence of exhumed mantle bordering the continental margins. Post-rift shallow-water platform carbonates indicate a delay in subsidence during rifting in the

  2. 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

  3. Microfluidic study on CNT dispersion during breakup of aqueous alginic acid drop in continuous PDMS phase

    NASA Astrophysics Data System (ADS)

    Choi, Jae Hong; Nam, Young Woo; Hong, Joung Sook

    2013-02-01

    Microfluidic study is performed to investigate how multi-walled carbon nanotube (CNTs) aggregates disperse in blend system during morphology evolution. As the dispersed phase, a drop containing CNT is generated at the flow focusing and it deforms through a contraction channel (gap and width of contraction ˜ 100 μm). When an aqueous polymeric drop (2 wt% alginic acid) with CNT (0.05 wt% or 0.5 wt%) is stretched through a 4:1 contraction channel, CNT aggregates enhances breakup of the stretched drop. Also, small droplets including CNTs are pinched off during relaxation of the stretched drop. Based on these observations, it is found that CNTs disperse in a multiphase system by repetitive breakup process during mixing rather than migration driven by chemical affinity.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    PubMed

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

    2016-08-21

    This paper describes 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. This paper shows 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. Fundamentally, the results represent a critical step towards the understanding of the physics governing instability in concentrated emulsions. Practically, the results provide a direct guide for the rational design of microchannels and the choice of operation parameters to increase the throughput of the droplet interrogation step while preserving droplet integrity and assay accuracy. PMID:27194099

  9. 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

  10. 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.

  11. Dynamics of polymeric drop breakup in microchannels

    NASA Astrophysics Data System (ADS)

    Arratia, Paulo; Gollub, Jerry; Durian, Douglas

    2006-11-01

    The dynamics of drop formation of sheared polymeric and Newtonian fluids are investigated in a 50 μm microchannel. Inverse emulsions are obtained in a cross-like geometry by impinging a continuous oil phase (with surfactant) onto either a polymeric or a Newtonian aqueous solution. The viscosity ratio between the continuous and dispersed phases is kept close to unity, and both flow rates are varied. Solutions containing small amounts (100 ppm) of flexible polymers strongly affect the filament and drop breakup processes when compared to a Newtonian solution of similar viscosity. We find that the thinning of the filament for the Newtonian case is characterized by linear decline followed by a rapid approach to breakup. The polymeric case shows an initial Newtonian-like thinning followed by a slower, elasticity- dominated thinning. Consequently, the filament breakup time and length are considerably increased for the polymeric solutions. Also, larger primary drops and beads-on-string phenomena are found for the polymer solutions.

  12. 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.

  13. 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.

  14. 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

  15. Transfer involving deformed nuclei

    SciTech Connect

    Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.

    1985-03-01

    Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs.

  16. Rapid three-dimensional passive rotation micromixer using the breakup process

    NASA Astrophysics Data System (ADS)

    Park, Sung-Jin; Kim, Jung Kyung; Park, Junha; Chung, Seok; Chung, Chanil; Chang, Jun Keun

    2004-01-01

    Stretching and folding, diffusion, and breakup are three basic processes that occur while mixing fluids. Although stretching and folding the interface of two fluids by rotation enables the mixing at microscale level in both low and high Reynolds number flows, rotation is not as effective at a low Reynolds number as at a high Reynolds number. Therefore, developing a rapid micromixer for microfluidic systems that can be used at a low Reynolds number is a challenging task, because it can demonstrate the full potential of microfluidic systems in commercial markets. Here, to enhance the mixing efficiency of a micromixer based on passive rotation, we present a breakup method. The breakup method not only generates interface actively but also enhances the diffusion process at the interface. With our novel design, over 70% mixing can be achieved only after passing through a 4 mm long microchannel. In this work, the mixer was easily fabricated with polydimethylsiloxane by soft lithography and a self-aligned bonding method with methanol. We analyzed the flow in the micromixer using the computational fluid dynamics method. Also, we conducted quantitative analyses using a confocal scanning microscope and image processing.

  17. Breakup locations: Intertwining effects of nuclear structure and reaction dynamics

    NASA Astrophysics Data System (ADS)

    Dasgupta, M.; Simpson, E. C.; Luong, D. H.; Kalkal, Sunil; Cook, K. J.; Carter, I. P.; Hinde, D. J.; Williams, E.

    2016-05-01

    Studies at the Australian National University aim to distinguish breakup of the projectile like-nucleus that occurs when approaching the target from that when receding from the target. Helped by breakup simulations, observables have been found that are sensitive to the breakup location, and thus to the mean-lives of unbound states; sensitivity to even sub-zeptosecond lifetime is found. These results provide insights to understand the reaction dynamics of weakly bound nuclei at near barrier energies.

  18. 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.

  19. Recent Breakups in the Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Nesvorny, D.

    2005-08-01

    Much of what we see in the asteroid belt today is a consequence of past collisions, which shaped the size-frequency distribution of asteroids and led to their heavily-cratered surfaces. Perhaps the most remarkable features of the belt are the asteroid families [1]. An asteroid family is a group of asteroid fragments with similar orbits and spectra produced by a collisional breakup of a large parent body. More than fifty families have been identified to date in the main belt [2]. These structures, when properly analyzed, hold important clues to the interior structure of asteroids, the physics of large scale collisions, and the overall evolution of the main belt since its formation [3]. Most of the known families are very old and thus have experienced significant dynamical and collisional erosion since their formation. This makes it difficult to clearly distinguish between features produced by the original breakup and those produced by on-going processes. Recent dynamical studies, however, have identified several asteroid families that are extremely young: the Iannini, Karin and Veritas families apparently formed at <5, 5.8 and 8.3 Ma, respectively [4,5]. These families represent nearly pristine examples of ejected fragments produced by disruptive asteroid collisions, because the observed remnants of recent breakups have apparently suffered limited dynamical and collisional erosion. Here we will discuss how studies of young asteroid families help us glean insights into the physics of large scale collisions, dynamical processes that affect small bodies in the Solar System, and the surface and interior properties of asteroids. [1] Hirayama, 1918, AJ 31, 185--188. [2] Zappala et al., 2002, In Asteroids III, pp. 619-629. [3] Bottke et al., 2005, Icarus, 175, 111-140. [4] Nesvorny et al., 2002, Nature 417, 720--722. [5] Nesvorny et al., 2003, ApJ 591, 486--497.

  20. Multipass Beam Breakup in Energy Recovery Linacs

    SciTech Connect

    Eduard Pozdeyev; Christopher Tennant; Joseph Bisognano; M Sawamura; R. Hajima; T.I. Smith

    2005-03-19

    This paper is a compilation of several presentations on multipass beam breakup (BBU) in energy recovery linacs (ERL) given at the 32nd Advanced ICFA Beam Workshop on ERLs. The goal of this paper is to summarize the progress achieved in analytical, numerical, and experimental studies of the instability and outline available and proposed BBU mitigation techniques. In this paper, a simplified theory of multipass BBU in recirculating linacs is presented. Several BBU suppression techniques and their working principles are discussed. The paper presents an overview of available BBU codes. Results of experimental studies of multipass BBU at the Jefferson Laboratory (JLab) FEL Upgrade are described.

  1. Pangea formation and break-up

    NASA Astrophysics Data System (ADS)

    Torsvik, Trond

    2013-04-01

    The Palaeozoic was dominated by the great continent Gondwana. Other continents included Laurentia and Baltica that fused (together with Avalonia), forming Laurussia after the closure of the Iapetus Ocean, making the second largest continental entity in the Silurian. By the Carboniferous at around 320 Ma, Gondwana and Laurussia amalgamated, forming Pangea that was surrounded by the Panthalassa and Paleotethys Oceans. Pangea did not include all continental crust. For example, the South and North China Blocks were not part of Pangea at any given time and also during the Early Permian phase of Pangea assembly, the Neotethys opened, and Cimmerian terranes drifted away from the NE Gondwana margin while the Paleotethys was being subducted beneath Eurasia. An additional, unresolved question is whether Siberia was fully joined to Pangea before the eruption of the Siberian Traps (251 Ma). Practically all Permian Pangea reconstructions using palaeomagnetic data result in considerable overlap between Laurussia and Gondwana, as both are straddling the equator, and thus Gondwana must be moved sideways to avoid this overlap, and at a younger time displaced dextrally to achieve the well established starting point for Pangea break-up in the Jurassic. Octupole contributions can eliminate this overlap, but just by changing the internal fits within Laurussia and correcting all detrital sedimentary poles for inclination shallowing using a use a benchmark flattening (f) value of 0.6 (unless previously corrected using either the inclination-elongation method or anisotropy of magnetic susceptibility information) lead to an almost perfect Pangea-A type fit. Pangea break-up profoundly changed our planet, and the most important phase of break-up started when the Central Atlantic Ocean opened (ca. 195 Ma). Perhaps not coincidentally, the region where the Atlantic spreading started was preceded by the emplacement of the Central Atlantic Magmatic Province, one of the largest large igneous

  2. Breakup of Liquid Sheets and Jets

    NASA Astrophysics Data System (ADS)

    Lin, S. P.

    2003-09-01

    This book is an exposition of what we know about the physics underlying the onset of instability in liquid sheets and jets. Wave motion and breakup phenomena subsequent to the onset of instability are also carefully explained. Physical concepts are established through mathematics, accurate numerical analysis and comparison of theory with experiments. Exercises are provided for students new to the subject. Researchers interested in topics ranging from transition to turbulence, hydrodynamic stability or combustion will find this book a useful resource, whether their background lies in engineering, physics, chemistry, biology, medicine or applied mathematics.

  3. Reentry Breakup Recorder: An Innovative Device for Collecting Data during Breakup of Reentering Objects

    NASA Astrophysics Data System (ADS)

    Ailor, W. H.; Weaver, M. A.

    2012-01-01

    More than 40 large, human-made, uncontrolled objects reenter the earth's atmosphere every year, and some fraction of the mass of each object survives to impact the ground or water. Some of these surviving objects are sizable and potentially hazardous. Recognizing this fact, space agencies are developing regulations and standards to limit ground hazards. Unfortunately, detailed information on how objects respond to the severe heating and loads environment is not available due to the difficulty in recording and broadcasting data during reentry and breakup. The Reentry Breakup Recorder (REBR) was developed using a different paradigm - rather than broadcasting data during the breakup event, record the data and broadcast it after the reentry has effectively ended, but before the data recorder actually impacts the Earth's surface. The paper describes how this approach minimizes the weight of the recording device and the overall cost of data recovery. The first flight tests of the REBR device were conducted in 2011; a REBR was inside the Japanese HTV2 and the European ATV-2 vehicles when they were deorbited into the Pacific Ocean. The paper presents a summary of the results of those tests and gives an overview of how future versions of REBR will revolutionize our understanding of reentry breakup and might be used to prototype "black box" systems for space transportation vehicles.

  4. 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.

  5. An Ellipsoidal Model for Secondary Breakup of Spray Droplets

    NASA Astrophysics Data System (ADS)

    Lundgren, T. S.

    1998-11-01

    In sprays of liquid drops dynamic interaction with the gas can cause drops to breakup into daughter drops. To analyse this situation it is assumed that the drop has the shape of a deformable ellipsoid of revolution. When placed in a stream the high stagnation pressure at the symmetry axis, coupled with Bernoulli suction around the equator tends to squeeze the drop into a lenticular shape. This is resisted by the inertia of the liquid and surface tension forces. This problem has been solved by matching together two exact potential flow solutions, allowing slip along the interface. The external flow is the solution for flow around an ellipsoidal body when it is moving with relative velocity into the gas. The internal flow of the liquid is an exact solution for flow inside a deforming ellipsoid, a uniform flow plus a uniaxial strain flow (a stagnation point flow). The boundary condition which matches the solutions at the interface, the balance of normal stresses with surface tension, is imposed only at the upstream axis and along the equator. The resulting equations give a second order differential equation for the aspect ratio of the drop. This is similar to the TAB model but nonlinear. A nonlinear oscillator. For small enough (constant) Weber number there is a stable solution at a certain aspect ratio; the drop can oscillate about this shape. When the Weber number is larger than a critical value the stable critical point disapears and the drop becomes unstable, with the equatorial radius growing until unbounded; the drop breaks.

  6. Relating Breakup and Incomplete Fusion of Weakly Bound Nuclei through a Classical Trajectory Model with Stochastic Breakup

    SciTech Connect

    Diaz-Torres, A.; Hinde, D. J.; Dasgupta, M.; Gasques, L. R.; Tostevin, J. A.

    2007-04-13

    A classical dynamical model that treats breakup stochastically is presented for low energy reactions of weakly bound nuclei. The three-dimensional model allows a consistent calculation of breakup, incomplete, and complete fusion cross sections. The model is assessed by comparing the breakup observables with continuum discretized coupled-channel quantum mechanical predictions, which are found to be in reasonable agreement. Through the model, it is demonstrated that the breakup probability of the projectile as a function of its distance from the target is of primary importance for understanding complete and incomplete fusion at energies near the Coulomb barrier.

  7. The cometary breakup hypothesis re-examined

    NASA Astrophysics Data System (ADS)

    La Violette, P. A.

    1987-02-01

    The theory that a Chiron-like progenitor of both Comet Encke and the Tunguska cosmic body may have fragmented beginning around 22,000 years BP and that debris from this breakup was responsible for producing the high heavy metal concentrations observed in the Late Wisconin stage polar ice is shown to be incorrectly founded. This paper reexamines the geochemical comparison which Clube and Napier (1984) make between the composition of the Tunguska cosmic body and elemental abundances previously reported for a sample of Sn-rich dust retrieved from the Wisconsin section of the Camp Century ice core. No evidence is found that would link these two sources to a common origin. Thus the hypothesis that a cometary breakup was responsible for modulating the earth's climate and perpetuating the last ice age is unfounded. On the other hand, evidence is presented indicating that debris from the Tunguska explosion may be present in a firm layer at Dome C, East Antarctica. Analysis of the geochemical data for this stratum leads to an estimate of 10 to the 6th to 10 to the 7th t for the mass of the Tunguska body, in approximate agreement with previous determinations.

  8. 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.

  9. 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.

  10. 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.

  11. 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…

  12. 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. PMID:21505441

  13. Condition of resonant break-up of gas bubbles by an acoustic wave in liquid

    NASA Astrophysics Data System (ADS)

    Vanovskiy, V. V.; Petrov, A. G.

    2016-07-01

    The linear theory of damping of radial vibrations of a bubble in a liquid is constructed by taking into account the key dissipative mechanisms: thermal, viscous, and acoustic. The basic approximation of homobaricity made helps to obtain the results in a convenient and simple form. The results obtained for damping are used further in the description of the forced resonant oscillations of a bubble in an acoustic wave with the frequency equal to the eigenfrequency of the radial oscillation mode and twice as high as the frequency of the deformation oscillation mode (resonance 2:2:1). It is shown that the amplitude of deformation oscillations, which is reasonably large for breaking, is developed at a relatively small pressure amplitude of the exciting acoustic wave, and subharmonics arise in the acoustic-emission spectrum. The condition of bubble break-up is obtained for a fast and slow start of the acoustic wave.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. Comment on breakup densities of hot nuclei

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

    In [V.E. Viola et al., Phys. Rev. Lett. 93 (2004) 132701, D.S. Bracken et al., Phys. Rev. C 69 (2004) 034612] the observed decrease in spectral peak energies of IMFs emitted from hot nuclei was interpreted in terms of a breakup density that decreased with increasing excitation energy. Subsequently, Raduta et al. [Ad. Raduta et al., Phys. Lett. B 623 (2005) 43] performed MMM simulations that showed decreasing spectral peaks could be obtained at constant density. In this Letter we point out that this apparent inconsistency is due to a selective comparison of theory and data that overlooks the evolution of the fragment multiplicities as a function of excitation energy.

  19. 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.

  20. 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.

  1. Calculating Beam Breakup in Superconducting Linear Accelerators

    SciTech Connect

    Geoffrey Krafft; Joseph Bisognano; Sharon Laubach

    1990-02-09

    As the intensity of a particle beam passing through a linear accelerator is raised, interactions between particles play an increasingly prominent role in determining the overall dynamics of the beam. These many body effects, known collectively as beam breakup, tend to degrade the quality of the transported beam, and hence they must be calculated to accurately predict the evolution of the beam as it traverses the accelerator. Several codes which compute various collective effects have been developed and used to simulate the dynamics of beams passing through superconducting accelerator structures. All the codes use the same basic algorithm: the beam is tracked through elements giving the focusing forces on the particles, and at the appropriate locations in the linac, localized forces are impressed on the particles which model the electromagnetic interactions. Here, a difficulty is that the usual ''Coulomb'' interaction between particles is changed by the electromagnetic environment of the accelerator. By such calculations it has been shown that recirculating linear accelerators such as the one being built at the Continuous Electron Beam Accelerator Facility (CEBAF) should remain stable against multipass beam breakup instability as long as the average current does not exceed about 20 mA, that the beam quality at CEBAF will be degraded when the single bunch charge approaches 10{sup 9} electrons, and that the beam quality of superconducting linacs that are optimized for high current transport begins to decrease at around 10{sup 10} electrons per bunch. The latter result is of interest to individuals who would use superconducting linacs as beam sources for free electron lasers or for superconducting colliders for high energy physics research.

  2. The Mesozoic breakup of the Weddell Sea

    NASA Astrophysics Data System (ADS)

    KöNig, Matthias; Jokat, Wilfried

    2006-12-01

    A new set of rotations is presented that describes a refined model for the early opening of the Weddell Sea between South America and Antarctica and the Mesozoic breakup of Gondwana. Published high-resolution aeromagnetic data from the eastern Weddell Sea and additional track data farther west in the Weddell Sea were used to constrain the new model for the opening of the Weddell Sea. Rotation parameters derived for the South America-Antarctica spreading regime were combined with constraints on the South America-Africa and Africa-Antarctica spreading systems to calculate a refined model for the Mesozoic breakup of Gondwana. Thereafter, at the time when the north-south oriented separation between Africa and Antarctica is initiated by rifting in the Somali and Mozambique basins (˜167 Ma), stretching and extension takes place in a basin comprising continental crust of the Filchner-Ronne Shelf, the Falkland Island block and the Maurice Ewing Bank. The first true ocean floor in the Weddell Sea is formed at about 147 Ma, after rifting between the Antarctic Peninsula and southernmost South America occurred. This is about 15-20 Myr later than previously estimated. Separation between South America and Antarctica takes place at slow spreading rates (14-12 mm/yr half rate) from 147 to 122 Ma and after 122 Ma (M2) at ultraslow spreading rates (˜8 mm/yr half rate) with little change in the NNW spreading direction throughout this time. A revised age range is proposed for the formation of the Explora Wedge (150-138 Ma), which is more than 30 Myr later than previously published (˜183 Ma).

  3. 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.

  4. 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.

  5. The TAB method for numerical calculation of spray droplet breakup

    NASA Astrophysics Data System (ADS)

    Orourke, P. J.; Amsden, A. A.

    A short history is given of the major milestones in the development of the stochastic particle method for calculating liquid fuel sprays. The most recent advance has been the discovery of the importance of drop breakup in engine sprays. A new method, called TAB, for calculating drop breakup is presented. Some theoretical properties of the method are derived; its numerical implementation in the computer program KIVA is described; and comparisons are presented between TAB-method calculations and experiments and calculations using another breakup model.

  6. 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

  7. Post-breakup Basin Evolution along the South-Atlantic Margins in Brazil and Angola/Namibia

    NASA Astrophysics Data System (ADS)

    Kukla, P. A.; Strozyk, F.; Back, S.

    2013-12-01

    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

  8. Field-aligned electron flux oscillations that produce flickering aurora

    NASA Technical Reports Server (NTRS)

    Mcfadden, J. P.; Carlson, C. W.; Boehm, M. H.; Hallinan, T. J.

    1987-01-01

    Measurements of energetic electrons that produce flickering aurora were made by a pair of sounding rockets, launched during a slowly evolving auroral breakup. Both payloads passed through a broad inverted-V structure. A component of the electron distribution function was closely aligned with the magnetic field over a broad energy range that extended from low energies up to the inverted-V differential energy flux peak. Measurements of the field-aligned component showed the presence of order of magnitude coherent flux oscillations. Source altitudes between 4000 and 8000 km were derived from velocity dispersion of the flux oscillations.

  9. ISS Update: ATV-3 ReEntry Breakup Recorder

    NASA Video Gallery

    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...

  10. 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.

  11. 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.

  12. Description of the four-nucleon collisions by including breakup

    NASA Astrophysics Data System (ADS)

    Lazauskas, Rimantas

    2016-03-01

    Four-nucleon reactions above the breakup threshold are described by solving Faddeev-Yakubovsky equations for the realistic nuclear Hamiltonians. Complex-scaling method is applied in order to simplify the boundary conditions.

  13. Tiny Traces of a Big Asteroid Breakup

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2004-03-01

    Ancient geologic conditions in southern Sweden were ideal to preserve meteorites that fell to Earth about half a billion years ago. Researcher Birger Schmitz (working as a visiting professor at Rice University and now at the University of Lund, Sweden) and his colleagues in Goteborg, Sweden have analyzed over 40 of these rare fossil meteorites along with relict chromite grains collected from sites in a 250,000-square-kilometer area of 480-million-year-old limestone. They attribute the abundance and wide distribution of this space debris to a meteorite influx at least one hundred times more intense than the influx today. Rather than a smorgasbord of different types, cosmochemical evidence shows that the fossil meteorites are L or LL chondrites leading the team to conclude that these meteorites and chromite grains derived from a major collision in the asteroid belt. The age of the limestone is very close to the impact age of many L chondrites suggesting that this major collision was the breakup of the L chondrite parent body, possibly the largest impact in the asteroid belt in the last few billion years.

  14. Degenerative Spinal Deformity.

    PubMed

    Ailon, Tamir; Smith, Justin S; Shaffrey, Christopher I; Lenke, Lawrence G; Brodke, Darrel; Harrop, James S; Fehlings, Michael; Ames, Christopher P

    2015-10-01

    Degenerative spinal deformity afflicts a significant portion of the elderly and is increasing in prevalence. Recent evidence has revealed sagittal plane malalignment to be a key driver of pain and disability in this population and has led to a significant shift toward a more evidence-based management paradigm. In this narrative review, we review the recent literature on the epidemiology, evaluation, management, and outcomes of degenerative adult spinal deformity (ASD). ASD is increasing in prevalence in North America due to an aging population and demographic shifts. It results from cumulative degenerative changes focused in the intervertebral discs and facet joints that occur asymmetrically to produce deformity. Deformity correction focuses on restoration of global alignment, especially in the sagittal plane, and decompression of the neural elements. General realignment goals have been established, including sagittal vertical axis <50 mm, pelvic tilt <22°, and lumbopelvic mismatch <±9°; however, these should be tailored to the patient. Operative management, in carefully selected patients, yields satisfactory outcomes that appear to be superior to nonoperative strategies. ASD is characterized by malalignment in the sagittal and/or coronal plane and, in adults, presents with pain and disability. Nonoperative management is recommended for patients with mild, nonprogressive symptoms; however, evidence of its efficacy is limited. Surgery aims to restore global spinal alignment, decompress neural elements, and achieve fusion with minimal complications. The surgical approach should balance the desired correction with the increased risk of more aggressive maneuvers. In well-selected patients, surgery yields excellent outcomes. PMID:26378361

  15. 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.

  16. A new model for auroral breakup during substorms

    SciTech Connect

    Rothwell, P.L.; Block, L.P.; Falthammar, C.G.; Silevitch, M.B.

    1989-04-01

    A model for substorm breakup is developed, based on the relaxation of stretched (closed) dipolar field lines, and the formation of an incipient current wedge within a single arc structure. It is argued that the establishment of a coupled current structure within a single arc leads to a quasi-stable system; i.e., the pre-breakup regime. Perturbation of the pre-breakup structure leads to an instability criterion. It is found, consistent with observations, that narrower auroral arcs at lower L shells undergo the most explosive poleward expansion. According to this model, the precise location at which breakup occurs depends on the O/sup +/ density in the plasma sheet, the level of magnetic activity (K/sub p/), and the intensity of the substorm westward electrojet in the ionosphere. An enhancement of any of these features will cause breakup to occur at lower L shells. Comparison of our model with the Heppner-Maynard polar-cap potential model indicates that breakup is restricted to the west of the Harang discontinuity consistent with recent observations from the Viking satellite.

  17. Droplet size distributions in turbulent emulsions: breakup criteria and surfactant effects from direct numerical simulations.

    PubMed

    Skartlien, R; Sollum, E; Schumann, H

    2013-11-01

    Lattice Boltzmann simulations of water-in-oil (W/O) type emulsions of moderate viscosity ratio (≃1/3) and with oil soluble amphiphilic surfactant were used to study the droplet size distribution in forced, steady, homogeneous turbulence, at a water volume fraction of 20%. The viscous stresses internal to the droplets were comparable to the interfacial stress (interfacial tension), and the droplet size distribution (DSD) equilibrated near the Kolmogorov scale with droplet populations in both the viscous and inertial subranges. These results were consistent with known breakup criteria for W/O and oil-in-water emulsions, showing that the maximum stable droplet diameter is proportional to the Kolmogorov scale when viscous stresses are important (in contrast to the inviscid Hinze-limit where energy loss by viscous deformation in the droplet is negligible). The droplet size distribution in the inertial subrange scaled with the known power law ~d(-10/3), as a consequence of breakup by turbulent stress fluctuations external to the droplets. When the turbulent kinetic energy was sufficiently large (with interfacial Péclet numbers above unity), we found that turbulence driven redistribution of surfactant on the interface inhibited the Marangoni effect that is otherwise induced by film draining during coalescence in more quiescent flow. The coalescence rates were therefore not sensitive to varying surfactant activity in the range we considered, and for the given turbulent kinetic energies. Furthermore, internal viscous stresses strongly influenced the breakup rates. These two effects resulted in a DSD that was insensitive to varying surfactant activity. PMID:24206328

  18. Droplet size distributions in turbulent emulsions: Breakup criteria and surfactant effects from direct numerical simulations

    NASA Astrophysics Data System (ADS)

    Skartlien, R.; Sollum, E.; Schumann, H.

    2013-11-01

    Lattice Boltzmann simulations of water-in-oil (W/O) type emulsions of moderate viscosity ratio (≃1/3) and with oil soluble amphiphilic surfactant were used to study the droplet size distribution in forced, steady, homogeneous turbulence, at a water volume fraction of 20%. The viscous stresses internal to the droplets were comparable to the interfacial stress (interfacial tension), and the droplet size distribution (DSD) equilibrated near the Kolmogorov scale with droplet populations in both the viscous and inertial subranges. These results were consistent with known breakup criteria for W/O and oil-in-water emulsions, showing that the maximum stable droplet diameter is proportional to the Kolmogorov scale when viscous stresses are important (in contrast to the inviscid Hinze-limit where energy loss by viscous deformation in the droplet is negligible). The droplet size distribution in the inertial subrange scaled with the known power law ˜d-10/3, as a consequence of breakup by turbulent stress fluctuations external to the droplets. When the turbulent kinetic energy was sufficiently large (with interfacial Péclet numbers above unity), we found that turbulence driven redistribution of surfactant on the interface inhibited the Marangoni effect that is otherwise induced by film draining during coalescence in more quiescent flow. The coalescence rates were therefore not sensitive to varying surfactant activity in the range we considered, and for the given turbulent kinetic energies. Furthermore, internal viscous stresses strongly influenced the breakup rates. These two effects resulted in a DSD that was insensitive to varying surfactant activity.

  19. Haglund's Deformity

    MedlinePlus

    ... Is Haglund’s Deformity? Haglund’s deformity is a bony enlargement on the back of the heel. The soft ... the Achilles tendon becomes irritated when the bony enlargement rubs against shoes. This often leads to painful ...

  20. Breakup and vaporization of droplets under locally supersonic conditions

    NASA Astrophysics Data System (ADS)

    Kim, YoungJun; Hermanson, James C.

    2012-07-01

    The disruption and vaporization of simulated fuel droplets in an accelerating supersonic flow was examined experimentally in a draw-down supersonic wind tunnel. The droplets achieved supersonic velocities relative to the surrounding air to give relative Mach numbers of up to 1.8 and Weber numbers of up to 300. Mono-disperse, 100 μm-diameter fluid droplets were generated using a droplet-on-demand generator upstream of the tunnel entrance. Direct close-up single- and multiple-exposure imaging was used to examine the features of droplet breakup and to determine the droplet velocities. Laser-induced fluorescence (LIF) imaging of the disrupting droplets was performed using acetone fluorescence to determine the dispersion of the expelled vapor. Three test liquids were employed: 2-propanol and tetraethylene glycol dimethyl ether as non-volatile fluids and a 50/50 hexanol-pentane mixture (Hex-Pen 50/50). The vapor pressure of the Hex-Pen 50/50 was sufficiently high to cause the droplet fluid to potentially become superheated in the decreased static pressure of the supersonic stream. The dynamics for 2-propanol and Hex-Pen 50/50 droplets were similar up to the point of disruption, which occurred more rapidly for the more volatile Hex-Pen 50/50. A 1D dynamic droplet model was developed to provide a first estimate of the expected droplet acceleration and velocity. The actual droplet velocities were in reasonable agreement with the model up to the point at which significant droplet disruption and mass loss commenced. The droplet deformation and breakup patterns for these supersonic flow conditions can be classified into four different flow regions characterized by changes in the Weber number with downstream distance as the droplets accelerate, however, those flow regimes and Weber number ranges were different than those seen for droplets disrupting in shock tubes. The disruption patterns were seen to be generally similar for the different fluids, though droplet disruption

  1. 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

  2. DNA Align Editor: DNA Alignment Editor Tool

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The SNPAlignEditor is a DNA sequence alignment editor that runs on Windows platforms. The purpose of the program is to provide an intuitive, user-friendly tool for manual editing of multiple sequence alignments by providing functions for input, editing, and output of nucleotide sequence alignments....

  3. 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. PMID:26341718

  4. 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.

    2010-03-01

    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. 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: high frequency oscillatory tests at frequencies up to 10 kHz, microfluidic shear rheometry at deformation rates up to 10^6 s-1 and the influence of transientextensional rheology in the jet breakup. The presence of inertial, elastic and viscous effects typically leads to complex dynamics in a necking fluid thread. We show that by carefully controlling the excitation frequency, it is possible to drive the break-up in a particularly simple and symmetric mode, which can be used to extract extensional viscosity information using capillary thinning analysis.

  5. 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. PMID:27375824

  6. 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.

  7. 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

  8. Hard breakup of two nucleons from the He3 nucleus

    NASA Astrophysics Data System (ADS)

    Sargsian, Misak M.; Granados, Carlos

    2009-07-01

    We investigate a large angle photodisintegration of two nucleons from the He3 nucleus within the framework of the hard rescattering model (HRM). In the HRM a quark of one nucleon knocked out by an incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with large relative momentum. Assuming the dominance of the quark-interchange mechanism in a hard nucleon-nucleon scattering, the HRM allows the expression of the amplitude of a two-nucleon breakup reaction through the convolution of photon-quark scattering, NN hard scattering amplitude, and nuclear spectral function, which can be calculated using a nonrelativistic He3 wave function. The photon-quark scattering amplitude can be explicitly calculated in the high energy regime, whereas for NN scattering one uses the fit of the available experimental data. The HRM predicts several specific features for the hard breakup reaction. First, the cross section will approximately scale as s-11. Second, the s11 weighted cross section will have the shape of energy dependence similar to that of s10 weighted NN elastic scattering cross section. Also one predicts an enhancement of the pp breakup relative to the pn breakup cross section as compared to the results from low energy kinematics. Another result is the prediction of different spectator momentum dependencies of pp and pn breakup cross sections. This is due to the fact that the same-helicity pp-component is strongly suppressed in the ground state wave function of He3. Because of this suppression the HRM predicts significantly different asymmetries for the cross section of polarization transfer NN breakup reactions for circularly polarized photons. For the pp breakup this asymmetry is predicted to be zero while for the pn it is close to (2)/(3).

  9. Middle-high latitude N2O distributions related to the arctic vortex breakup

    NASA Astrophysics Data System (ADS)

    Zhou, L. B.; Zou, H.; Gao, Y. Q.

    2006-03-01

    The relationship of N2O distributions with the Arctic vortex breakup is first analyzed with a probability distribution function (PDF) analysis. The N2O concentration shows different distributions between the early and late vortex breakup years. In the early breakup years, the N2O concentration shows low values and large dispersions after the vortex breakup, which is related to the inhomogeneity in the vertical advection in the middle and high latitude lower stratosphere. The horizontal diffusion coefficient (K,,) shows a larger value accordingly. In the late breakup years, the N2O concentration shows high values and more uniform distributions than in the early years after the vortex breakup, with a smaller vertical advection and K,, after the vortex breakup. It is found that the N2O distributions are largely affected by the Arctic vortex breakup time but the dynamically defined vortex breakup time is not the only factor.

  10. 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.

  11. 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.

  12. 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.

  13. 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. PMID:26986389

  14. Dynamics of bubble breakup at a T junction

    NASA Astrophysics Data System (ADS)

    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. 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.

  16. Breakup Reactions of Neutron Drip Line Nuclei Near N=20

    NASA Astrophysics Data System (ADS)

    Nakamura, Takashi

    2011-09-01

    Coulomb breakup at intermediate energies is a useful experimental tool for investigating the microscopic structure of neutron drip-line nuclei. Here, results from the inclusive Coulomb breakup experiment of 31Ne on a lead target at RIBF(RI Beam Factory) at RIKEN are presented. The experiment was performed as one of day-one campaign experiments at RIBF, using a 48Ca primary beam at 345 MeV/nucleon. A unique feature of a halo nucleus is the enhanced electric dipole strength of the order of 1 W.u.(Weisskopf unit) at very low excitation energies around 1 MeV (soft E1 excitation). Owing to high sensitivity of the Coulomb breakup to the soft E1 excitation, a measurement of inclusive Coulomb breakup cross section can be used to identify the halo structure of a certain drip-line nucleus. We have indeed observed a strong enhancement of the Coulomb breakup cross section of 540(70) mb for 31Ne on Pb at 230 MeV/nucleon, nearly as high as that for the known halo nucleus 19C, thereby giving evidence of the halo structure in 31Ne. The finding of a new halo structure for such a heavy system, compared to the known halo nuclei, is the first step for the understanding of halo phenomena along the neutron drip line towards heavier nuclei. We discuss also the change of shell structure in 31Ne, as a nucleus in the island of inversion.

  17. 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.

  18. 3D Dynamics of Oblique Rift Systems: Fault Evolution from Rift to Break-up

    NASA Astrophysics Data System (ADS)

    Brune, S.

    2014-12-01

    Rift evolution and passive margin formation has been thoroughly investigated using conceptual and numerical models in two dimensions. However, the 2D assumption that the extension direction is perpendicular to the rift trend is often invalid. In fact, the majority of rift systems that lead to continental break-up during the last 150 My involved moderate to high rift obliquity. Yet, the degree to which oblique lithospheric extension affects first-order rift and passive margin properties like surface stress pattern, fault azimuths, and basin geometry, is still not entirely clear. This contribution provides insight in crustal stress patterns and fault orientations by applying a 3D numerical rift model to oblique extensional settings. The presented forward experiments cover the whole spectrum of oblique extension (i.e. rift-orthogonal extension, low obliquity, high obliquity, strike-slip deformation) from initial deformation to breakup. They are conducted using an elasto-visco-plastic finite element model and involve crustal and mantle layers accounting for self-consistent necking of the lithosphere. Even though the model setup is very simple (horizontally layered, no inherited faults), its evolution exhibits a variety of fault orientations that are solely caused by the interaction of far-field stresses with rift-intrinsic buoyancy and strength. Depending on rift obliquity, these orientations involve rift-parallel, extension-orthogonal, and intermediate normal fault directions as well as strike-slip faults. Allowing new insights on fault patterns of the proximal and distal margins, the model shows that individual fault populations are activated in a characteristic multi-phase evolution driven by lateral density variations of the evolving rift system. Model results are in very good agreement with inferences from the well-studied Gulf of Aden and provide testable predictions for other rifts and passive margins worldwide.

  19. 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.

  20. 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.

  1. Universality for the breakup of invariant tori in Hamiltonian flows

    NASA Astrophysics Data System (ADS)

    Chandre, C.; Govin, M.; Jauslin, H. R.; Koch, H.

    1998-06-01

    In this article, we describe a new renormalization-group scheme for analyzing the breakup of invariant tori for Hamiltonian systems with two degrees of freedom. The transformation, which acts on Hamiltonians that are quadratic in the action variables, combines a rescaling of phase space and a partial elimination of irrelevant (nonresonant) frequencies. It is implemented numerically for the case applying to golden invariant tori. We find a nontrivial fixed point and compute the corresponding scaling and critical indices. If one compares flows to maps in the canonical way, our results are consistent with existing data on the breakup of golden invariant circles for area-preserving maps.

  2. On Slater's criterion for the breakup of invariant curves

    NASA Astrophysics Data System (ADS)

    Abud, C. V.; Caldas, I. L.

    2015-07-01

    We numerically explore Slater's theorem in the context of dynamical systems to study the breakup of invariant curves. Slater's theorem states that an irrational translation over a circle returns to an arbitrary interval in at most three different recurrence times expressible by the continued fraction expansion of the related irrational number. The hypothesis considered in this paper is that Slater's theorem can be also verified in the dynamics of invariant curves. Hence, we use Slater's theorem to develop a qualitative and quantitative numerical approach to determine the breakup of invariant curves in the phase space of area-preserving maps.

  3. Deformation studies of near single-crystal triblock copolymers

    SciTech Connect

    Honeker, C.; Villar, M.A.; Thomas, E.L.

    1993-12-31

    The mechanical behavior of block copolymers is being studied in order to determine the evolution of the microphase-separation morphologies with deformation. To facilitate analysis a novel processing technique termed {open_quotes}roll-casting{close_quotes} is used to orient the copolymers. Large, near single-crystal macroscopically oriented films are produced by applying a shear field on a homogeneous solution and allowing the solvent to evaporate until the copolymer has microphase separated. Deformation behavior is studied with in situ small angle x-ray diffraction and TEM studies of films deformed up to 700% extension. Initial studies on poly(styrene-butadiene-styrene) triblock copolymers with a cylindrical morphology indicate a break-up of the morphology at low deformations and a development of a characteristic 4 point pattern at high deformations. Hysteresis is observed in deformation directions of 0 and 90 degrees.

  4. 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.

  5. 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.

  6. 24 CFR 982.315 - Family break-up.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... an occurrence of domestic violence, dating violence, or stalking as provided in 24 CFR part 5... provided in 24 CFR part 5, subpart L, and whether the abuser is still in the household. (5) Other factors... 24 Housing and Urban Development 4 2014-04-01 2014-04-01 false Family break-up. 982.315...

  7. 24 CFR 982.315 - Family break-up.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... an occurrence of domestic violence, dating violence, or stalking as provided in 24 CFR part 5... provided in 24 CFR part 5, subpart L, and whether the abuser is still in the household. (5) Other factors... 24 Housing and Urban Development 4 2012-04-01 2012-04-01 false Family break-up. 982.315...

  8. 24 CFR 982.315 - Family break-up.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... an occurrence of domestic violence, dating violence, or stalking as provided in 24 CFR part 5... provided in 24 CFR part 5, subpart L, and whether the abuser is still in the household. (5) Other factors... 24 Housing and Urban Development 4 2013-04-01 2013-04-01 false Family break-up. 982.315...

  9. 24 CFR 982.315 - Family break-up.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... an occurrence of domestic violence, dating violence, or stalking as provided in 24 CFR part 5... provided in 24 CFR part 5, subpart L, and whether the abuser is still in the household. (5) Other factors... 24 Housing and Urban Development 4 2011-04-01 2011-04-01 false Family break-up. 982.315...

  10. A Cure for Multipass Beam Breakup in Recirculating Linacs

    SciTech Connect

    Byung C. Yunn

    2004-07-02

    We investigate a method to control the multipass dipole beam breakup instability in a recirculating linac including energy recovery. Effectiveness of an external feedback system for such a goal is shown clearly in a simplified model. We also verify the theoretical result with a simulation study.

  11. A METHOD TO CONTROL MULTIPASS BEAM BREAKUP IN RECIRCULATING LINACS

    SciTech Connect

    Byung Yunn

    2003-05-01

    We investigate a method to control the multipass dipole beam breakup instability in a recirculating linac including energy recovery. Effectiveness of an external feedback system for such a goal is shown clearly in a simplified model. We also verify the theoretical result with a simulation study.

  12. 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 982.315 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR PUBLIC AND INDIAN HOUSING, DEPARTMENT OF HOUSING AND URBAN...

  13. 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…

  14. Breakup of three particles within the adiabatic expansion method

    NASA Astrophysics Data System (ADS)

    Garrido, E.; Kievsky, A.; Viviani, M.

    2014-07-01

    General expressions for the breakup cross sections in the laboratory frame for 1+2 reactions are given in terms of the hyperspherical adiabatic basis. The three-body wave function is expanded in this basis and the corresponding hyperradial functions are obtained by solving a set of second order differential equations. The S matrix is computed by using two recently derived integral relations. Even though the method is shown to be well suited to describe 1+2 processes, there are particular configurations in the breakup channel (for example, those in which two particles move away close to each other in a relative zero-energy state) that need a huge number of basis states. This pathology manifests itself in the extremely slow convergence of the breakup amplitude in terms of the hyperspherical harmonic basis used to construct the adiabatic channels. To overcome this difficulty the breakup amplitude is extracted from an integral relation as well. For the sake of illustration, we consider neutron-deuteron scattering. The results are compared to the available benchmark calculations.

  15. Modelling magnetically deformed neutron stars

    NASA Astrophysics Data System (ADS)

    Haskell, B.; Samuelsson, L.; Glampedakis, K.; Andersson, N.

    2008-03-01

    Rotating deformed neutron stars are important potential sources for ground-based gravitational wave interferometers such as LIGO, GEO600 and VIRGO. One mechanism that may lead to significant non-asymmetries is the internal magnetic field. It is well known that a magnetic star will not be spherical and, if the magnetic axis is not aligned with the spin axis, the deformation will lead to the emission of gravitational waves. The aim of this paper is to develop a formalism that would allow us to model magnetically deformed stars, using both realistic equations of state and field configurations. As a first step, we consider a set of simplified model problems. Focusing on dipolar fields, we determine the internal magnetic field which is consistent with a given neutron star model and calculate the associated deformation. We discuss the relevance of our results for current gravitational wave detectors and future prospects.

  16. 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

  17. Nearest Alignment Space Termination

    Energy Science and Technology Software Center (ESTSC)

    2006-07-13

    Near Alignment Space Termination (NAST) is the Greengenes algorithm that matches up submitted sequences with the Greengenes database to look for similarities and align the submitted sequences based on those similarities.

  18. Shiva automatic pinhole alignment

    SciTech Connect

    Suski, G.J.

    1980-09-05

    This paper describes a computer controlled closed loop alignment subsystem for Shiva, which represents the first use of video sensors for large laser alignment at LLNL. The techniques used on this now operational subsystem are serving as the basis for all closed loop alignment on Nova, the 200 terawatt successor to Shiva.

  19. Fast statistical alignment.

    PubMed

    Bradley, Robert K; Roberts, Adam; Smoot, Michael; Juvekar, Sudeep; Do, Jaeyoung; Dewey, Colin; Holmes, Ian; Pachter, Lior

    2009-05-01

    We describe a new program for the alignment of multiple biological sequences that is both statistically motivated and fast enough for problem sizes that arise in practice. Our Fast Statistical Alignment program is based on pair hidden Markov models which approximate an insertion/deletion process on a tree and uses a sequence annealing algorithm to combine the posterior probabilities estimated from these models into a multiple alignment. FSA uses its explicit statistical model to produce multiple alignments which are accompanied by estimates of the alignment accuracy and uncertainty for every column and character of the alignment--previously available only with alignment programs which use computationally-expensive Markov Chain Monte Carlo approaches--yet can align thousands of long sequences. Moreover, FSA utilizes an unsupervised query-specific learning procedure for parameter estimation which leads to improved accuracy on benchmark reference alignments in comparison to existing programs. The centroid alignment approach taken by FSA, in combination with its learning procedure, drastically reduces the amount of false-positive alignment on biological data in comparison to that given by other methods. The FSA program and a companion visualization tool for exploring uncertainty in alignments can be used via a web interface at http://orangutan.math.berkeley.edu/fsa/, and the source code is available at http://fsa.sourceforge.net/. PMID:19478997

  20. 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.

  1. Similarity between the primary and secondary air-assisted liquid jet breakup mechanisms.

    PubMed

    Wang, Yujie; Im, Kyoung-Su; Fezzaa, Kamel

    2008-04-18

    We report an ultrafast synchrotron x-ray phase-contrast imaging study of the primary breakup mechanism of a coaxial air-assisted water jet. There exist great similarities between the primary (jet) and the secondary (drop) breakup, and in the primary breakup on different length scales. A transition from a ligament- to a membrane-mediated breakup is identified around an effective Weber number We' approximately 13. This observation reveals the critical role an effective Weber number plays in determining the atomization process and strongly supports the cascade breakup model. PMID:18518113

  2. 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

  3. 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. PMID:3786010

  4. Mechanisms and systematics of breakup in reactions of {sup 9}Be at near-barrier energies

    SciTech Connect

    Rafiei, R.; Rietz, R. du; Luong, D. H.; Hinde, D. J.; Dasgupta, M.; Evers, M.; Diaz-Torres, A.

    2010-02-15

    Below-barrier no-capture breakup measurements of the weakly bound {sup 9}Be nucleus, incident on targets ranging in atomic number from 62 to 83, have been carried out using a large-area high-resolution back-angle detector array. It is shown that the three-body reconstructed reaction Q-value and relative energy of the breakup fragments together reveal the full dynamics of the breakup mechanism, identifying all physical processes that lead to the breakup of the projectile-like nucleus. Contrasting with the simple expectation of direct breakup into the most energetically favored clusters, the data show that breakup following n-transfer dominates the total breakup yield. Breakup from long-lived states in the projectile-like nucleus, which on the reaction time scale may be considered stable, has been isolated from the prompt breakup yield. It has been shown that the prompt breakup probability essentially depends on the surface separation of the interacting nuclei. The measured prompt breakup probability functions for each target have been used together with a classical trajectory model to predict the above-barrier suppression of complete fusion. The suppression factor, expressed as the fraction of incomplete fusion, is nearly independent of target charge.

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

    PubMed

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

    2015-01-01

    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. PMID:25316203

  6. The Davie Ridge: a Marginal Transform Ridge not Formed During Continental Breakup

    NASA Astrophysics Data System (ADS)

    Phethean, J. J. J.; Van Hunen, J.; McCaffrey, K. J. W.; Davies, R. J.

    2014-12-01

    The breakup of Gondwana translated Madagascar southwards relative to Africa along the Davie Fracture Zone (DFZ). This fracture zone now forms the Transform Passive Continental Margin (TPCM) from Kenya to Mozambique. The Davie Ridge (DR), a transform marginal ridge, has formed along the DFZ between 5 and 2°S and 22 and 11°S, but with little expression in-between. It has been proposed that this marginal ridge was formed by the thermal effects of a passing Mid Ocean Ridge (MOR) during the separation of Gondwana. Plate kinematic reconstructions, however, constrained by ocean magnetic anomalies, show that the MOR only passed between the north and south expressions of the DR. Therefore the positive linear gravity anomalies of the DR cannot be attributed to the effects of a passing MOR, and some other mechanism must be found to explain their formation. Interpretation of seismic reflection profiles along the DR shows that the gravity highs occur adjacent to large basin structures. In the north this correlates with a basin-bounding basement high of ~Albian age, and in the south with the rift flank uplifts of the currently active Quirimbas graben. This suggests that the northern and southern DR segments are instead shoulder uplifts resulting from two separate extensional episodes during different stress regimes. These are the Cretaceous NE-SW extension during the breakup of the south Atlantic, and the E-W extension of the Neogene-recent Afar-East Africa rift system, respectfully. The lack of deformation and DR formation along the region of the TPCM passed by the MOR suggests it has been coupled by thermal effects and/or the injection of magma.

  7. 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.

  8. Recent results of invariant torus breakup in nontwist maps

    NASA Astrophysics Data System (ADS)

    Wurm, Alexander; Fuchss, Kathrin; Morrison, P. J.

    2006-10-01

    As simple models for degenerate Hamiltonian systems, nontwist maps have been used to describe, e.g., magnetic field lines in toroidal plasma devices with reversed magnetic shear profiles. Of particular interest in these maps are the so-called shearless invariant tori which correspond to transport barries in the physical system. We investigate the breakup of shearless tori in several maps and with several different winding numbers, in order to understand the dependence of the details of the breakup on the winding number and on the symmetries of the map model. Here we report on recent results of this investigation.[1][1] K. Fuchss, A. Wurm, A. Apte, and P.J. Morrison, to appear in Chaos (2006); K. Fuchss, A. Wurm, and P.J. Morrison, preprint/submitted to PRL (2006).

  9. Elastic breakup cross sections of well-bound nucleons

    NASA Astrophysics Data System (ADS)

    Wimmer, K.; Bazin, D.; Gade, A.; Tostevin, J. A.; Baugher, T.; Chajecki, Z.; Coupland, D.; Famiano, M. A.; Ghosh, T. K.; Grinyer, G. F.; Howard, M. E.; Kilburn, M.; Lynch, W. G.; Manning, B.; Meierbachtol, K.; Quarterman, P.; Ratkiewicz, A.; Sanetullaev, A.; Showalter, R. H.; Stroberg, S. R.; Tsang, M. B.; Weisshaar, D.; Winkelbauer, J.; Winkler, R.; Youngs, M.

    2014-12-01

    The 9Be(28Mg,27Na ) one-proton removal reaction with a large proton separation energy of Sp(28Mg ) =16.79 MeV is studied at intermediate beam energy. Coincidences of the bound 27Na residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the removal of more weakly bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement.

  10. Core transitions in the breakup of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Summers, N. C.; Nunes, F. M.; Thompson, I. J.

    2006-03-01

    An interesting physical process has been unveiled: Dynamical core excitation during a breakup reaction of loosely bound core+N systems. These reactions are typically used to extract spectroscopic information and/or astrophysical information. A new method, the eXtended Continuum Discretized Coupled Channel (XCDCC) method, was developed to incorporate, in a consistent way and to all orders, core excitation in the bound and scattering states of the projectile, as well as dynamical excitation of the core as it interacts with the target. The model predicts cross sections to specific states of the core. It is applied to the breakup of Be11 on Be9 at 60 MeV/nucleon, and the calculated cross sections are in improved agreement with the data. The distribution of the cross section amongst the various core states is shown to depend on the reaction model used, and not simply on the ground state spectroscopic factors.

  11. High Energy Break-Up of Few-Nucleon Systems

    NASA Astrophysics Data System (ADS)

    Sargsian, Misak

    2008-03-01

    We discus recent developments in theory of high energy two-body break-up reactions of few-nucleon systems. The characteristics of these reactions are such that the hard two-body quasielastic subprocess can be clearly separated from the accompanying soft subprocesses. We discuss in details the hard rescattering model (HRM) in which hard photodisintegration develops in two stages. At first, photon knocks-out an energetic quark which rescatters subsequently with a quark of the other nucleon. The latter provides a mechanism of sharing the initial high momentum of the photon by the outgoing two nucleons. Within HRM we discuss hard break-up reactions involving 2D and 3He targets. Another development of HRM is the prediction of new helicity selection mechanism for hard two-body reactions, which was apparently confirmed in the recent JLab experiment.

  12. 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.

  13. Study of transfer and breakup reactions with the plastic box

    SciTech Connect

    Stokstad, R.G.; Albiston, C.R.; Bantel, M.; Chan, Y.; Countryman, P.J.; Gazes, S.; Harvey, B.G.; Homeyer, H.; Murphy, M.J.; Tserruya, I.

    1984-12-01

    The study of transfer reactions with heavy-ion projectiles is complicated by the frequent presence of three or more nuclei in the final state. One prolific source of three-body reactions is the production of a primary ejectile in an excited state above a particle threshold. A subset of transfer reactions, viz., those producing ejectiles in bound states, can be identified experimentally. This has been accomplished with a 4..pi.. detector constructed of one-millimeter-thick scintillator paddles of dimension 20 cm x 20 cm. The paddles are arranged in the form of a cube centered around the target with small entrance and exit apertures for the beam and the projectile-like fragments, (PLF). The detection of a light particle (e.g., a proton or an alpha particle) in coincidence with a PLF indicates a breakup reaction. The absence of any such coincidence indicates a reaction in which all the charge lost by the projectile was transferred to the target. With this technique we have studied the transfer and breakup reactions induced by 220 and 341 MeV /sup 20/Ne ions on a gold target. Ejectiles from Li to Ne have been measured at several scattering angles. The absolute cross sections, angular distributions and energy spectra for the transfer and breakup reactions are presented. Relatively large cross sections are observed for the complete transfer of up to seven units of charge (i.e., a nitrogen nucleus). The relatively large probabilities for ejectiles to be produced in particle-bound states suggest that on the average, most of the excitation energy in a collision resides in the heavy fragment when mass is transferred from the lighter to the heavier fragment. The gross features and trends in the energy spectra for transfer and breakup reactions are similar. 20 references.

  14. 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.

  15. 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.

  16. JET BREAKUP AND SPRAY FORMATION IN A DIESEL ENGINE.

    SciTech Connect

    GLIMM,J.; LI,X.; KIM,M.N.; OH,W.; MARCHESE,A.; SAMULYAK,R.; TZANOS,C.

    2003-06-17

    The breakup of injected fuel into spray is of key interest to the design of a fuel efficient, nonpolluting diesel engine. We report preliminary progress on the numerical simulation of diesel fuel injection spray with the front tracking code FronTier. Our simulation design is set to match experiments at ANL, and our present agreement is semi-quantitative. Future efforts will include mesh refinement studies, which will better model the turbulent flow.

  17. 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,…

  18. Dynamics of Cold-Air Pool Breakup: Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Lareau, N.; Horel, J.

    2013-12-01

    Persistent cold-air pools (CAPs) impact urban mountain valleys during the winter leading to prolonged episodes of unhealthy air quality. One associated scientific challenge is accurately forecasting the breakup of these CAPs. For example, there is often uncertainty regarding the interaction of passing weather systems with the stratification within a valley. Will the disturbance be sufficient to destroy the CAP, or will the CAP persist for many more days bringing continued elevated levels of pollution? To address these questions this study examines the dynamical processes that affect the time scale and character of CAP breakup. To do so we use idealized large eddy simulations (LES) to examine the sensitivity of CAP removal to variations in wind, topography, and stratification. The simulations are based on field observations from the Persistent Cold-Air Pool Study (PCAPS). Results indicate that the upstream terrain-flow interaction is important in controlling both the timescale and structure of the CAP breakup. For example, when the flow plunges over the confining topography it leads to enhanced turbulent mixing, CAP displacement, and shorter timescales for complete CAP removal. In contrast, when no mountain wave is present the upstream edge of the CAP remains sheltered from the wind-driven mixing and the break-up is first observed over downstream portions of the basin. Meanwhile, changes in the CAP stratification impact internal circulations that develop in response to the imposed wind forcing. These circulations have significance for the distribution of pollution within CAPs. A concise summary of these results will be presented. Snapshot from a simulation of strong winds disrupting a CAP confined between two ridges. Potential temperature (a), vertical velocity (b), and wind speed (c).

  19. 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.

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

    SciTech Connect

    Li, H.

    1990-12-31

    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.

  1. 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.

  2. The breakup of thin air films caught under impacting drops

    NASA Astrophysics Data System (ADS)

    Thoroddsen, Sigurdur; Thoraval, Marie-Jean; Takehara, Kohsei; Etoh, T. Goji

    2012-11-01

    When a drop impacts a pool at very low velocities V, an air layer cushions the impact and prevents immediate contact. This air layer is stretched into a hemispheric shape and thins to a submicron thickness. We use silicone oils, where these films are more stable than for water [Saylor & Bounds (2012), AIChE J., online: doi 10.1002/aic.13764 ]. We observe three main breakup mechanisms which are imprinted onto the micro-bubble morphology. First, for lowest V the film ruptures at isolated holes which grow rapidly, leaving bubble necklaces where their edges meet. Based on micro-bubble volumes, we show the film breaks by van der Waals, when its thickness ~ 100 nm. Secondly, for slightly larger V a ring of holes appearing a fixed depth, where the film is thinnest, producing bubble chandeliers. Finally, for larger V an air jet within the drop, ruptures it at the bottom tip, in an axisymmetric breakup. We measure the rupture speed and find that for very viscous liquids, the breakup moves faster than the capillary-viscous velocity, through the repeated ruptures. [Thoroddsen, Thoraval, Takehara & Etoh (2012), J. Fluid Mech. online: doi:10.1017/jfm.2012.319].

  3. Droplet Breakup and Other Problems Involving Surface Tension Driven Flows.

    NASA Astrophysics Data System (ADS)

    Brenner, Michael P.

    We explore several problems involving fluid flows driven by surface tension. The first part of the thesis concerns droplet breakup. The major focus is on the formation of singularities occurring when a mass of fluid breaks into two pieces. We explore this phenomena in many different physical situations, including droplet breakup in a Hele Shaw cell, rupturing of thin films on a solid surface, the breaking of Plateau borders in soap froths, and fluid dripping from a cylindrical nozzle. In most of the above examples the singularities are characterized by self similar solutions of nonlinear partial differential equations. For the dripping faucet, the similarity solution is unstable to finite (but small) amplitude perturbations; the consequence of this is that in practice the breakup of a three dimensional droplet is a nonsteady process, with new structures continually generated as the interface breaks. Through asymptotic analysis, we show that the amount of noise necessary to destabilize the similarity solution decreases rapidly as the singularity is approached. For fluids of moderate viscosity fluctuations in the interfacial shape of atomic size are sufficient to destabilize the interface when the thickness is less than one micron. The second part of the thesis addresses problems in wetting. We present an analysis of a droplet spreading on a solid surface, which results in an understanding of the experimentally observed spreading laws. Finally, we present an explanation of the mechanism for the instability that occurs when a contact line is driven by a constant force. The explanation is consistent with recent experimental data.

  4. Hard breakup of the deuteron into two Δ -isobars

    NASA Astrophysics Data System (ADS)

    Granados, Carlos; Sargsian, Misak

    2011-04-01

    Photodisintegration of the deuteron into two Δ-isobars at large center of mass angles is studied within the QCD hard rescattering model (HRM). According to the HRM, the reaction proceeds in three main steps: the photon knocks the 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 emerging at large transverse momenta. Within the HRM, the cross section is expressed through the amplitude of pn --> ΔΔ scattering which we evaluated based on the quark-interchange model of hard hadronic scattering. We predict that the cross section of the deuteron breakup to Δ++Δ- is 4-5 times larger than that of the breakup to the Δ+Δ0 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 Δ-isobars are the result of the disintegration of initial ΔΔ components of the deuteron wave function. In this case, the angular distributions and cross sections of the breakup in both Δ++Δ- and Δ+Δ0 channels are expected to be similar. This work was supported by U.S. Department of Energy Grant under contract DE-FG02-01ER41172, and by the FIU DEA program.

  5. Hard breakup of the deuteron into two Δ isobars

    NASA Astrophysics Data System (ADS)

    Granados, Carlos G.; Sargsian, Misak M.

    2011-05-01

    We study high-energy photodisintegration of the deuteron into two Δ 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→ΔΔ 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→ΔΔ scattering. We predict that the cross section of the deuteron breakup to Δ++Δ- is 4-5 times larger than that of the breakup to the Δ+Δ0 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 Δ isobars are the result of the disintegration of the preexisting ΔΔ components of the deuteron wave function. In this case, one expects the angular distributions and cross sections of the breakup in both Δ++Δ- and Δ+Δ0 channels to be similar.

  6. Breakup of the Bell monopoly: Lessons for electric utilities

    SciTech Connect

    Piepmeier, J.M. ); Jermain, D.O. ); Egnor, T.L. )

    1993-07-01

    Technological change, not regulatory change, was the prime mover behind the Bell breakup. Now, for the first time, technology threatens to recast the economic structure of the electric utility industry as well. Previous analyses of the restructuring of the telecommunications industry, as represented by the 1984 breakup of the Bell monopoly, focus on regulatory change as the precipitator and principal agent. Technology is recognized as an important factor but not the primary trigger. This view confounds the roles of the independent and dependent variables in the economic system. The mistake is more than misperception of a single, isolated event that is now over and done with; it is fundamental and it must be corrected in order to understand the implications that restructuring holds for electric utility monopolies. Technology, not regulation, was the primary trigger in the Bell System breakup. Technology acted as a virus, infecting the monopoly economics of telecommunications and in turn driving a complete transformation of that industry. Regulatory change was the consequence, not the cause.

  7. Nonlinear dynamics and breakup of free-surface flows

    SciTech Connect

    Eggers, J.

    1997-07-01

    Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems. {copyright} {ital 1997} {ital The American Physical Society}

  8. FEM calculations of drop breakup beyond the first singularity

    NASA Astrophysics Data System (ADS)

    Suryo, Ronald; Basaran, Osman

    2007-11-01

    Computational analysis of drop breakup, which is of common occurrence in nature and technology, is important for advancing understanding of pinch-off singularities and developing new technologies. During drop formation from a tube, as more liquid flows from the tube into the drop, the drop elongates and thins. At the incipience of breakup, a spherical mass -- the precursor of the primary drop -- is connected to the liquid in the tube by a thin thread -- the precursor of one or more satellites. Numerical algorithms for analyzing this phenomenon at finite Reynolds number have been of two types: ones based on finite element methods (FEMs) and others based on various diffuse interface (DI) techniques. Numerical solutions must agree with scaling solutions of interface pinch-off, which are exact solutions of the nonlinear Navier-Stokes equations, and experiments. To date, the DI approach, despite its coarseness, has been more popular because it is simple and can predict the formation of several drops in sequence. Predictions made with FEM algorithms have been shown to be in excellent agreement with scaling theories and measurements but only until the instant of first breakup. Here we describe new FEM computations of unparalleled accuracy to predict the dynamics of continuous drop formation and support them with high-speed visualization experiments.

  9. 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).

  10. Inverted Break-up Behaviour in Continuous Inkjet (CIJ) Printing

    NASA Astrophysics Data System (ADS)

    McIlroy, Claire; Harlen, Oliver; Morrison, Neil

    2014-11-01

    Although droplet creation during continuous jetting of Newtonian fluids has been widely studied, unsolved problems surrounding the break-up dynamics remain. Jetting through a nozzle creates a stream of liquid that is rendered unstable by surface tension. This instability creates a succession of main drops connected by thin filaments, with drop separation determined by the fastest growing wavelength. In order to control break-up and increase printing speeds, continuous inkjet (CIJ) printing exploits the effects of finite amplitude modulations in the jet velocity profile giving conditions where jet stability deviates from the usual Rayleigh behaviour. To explore these non-linear effects, we have developed a one-dimensional jetting model. In particular, we identify a modulation range for which pinching occurs upstream of the connecting filament, rather than downstream - a phenomenon we call ``inverted'' break-up. Furthermore, this behaviour can be controlled by the addition of harmonics to the initial driving signal. Our results are compared to full axisymmetric simulations in order to incorporate the effects of nozzle geometry. EPSRC Innovation in Industrial Technology.

  11. 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.

  12. A methodology of MSL breakup analysis for Earth accidental reentry and its application to breakup analysis for Mars off-nominal entry

    NASA Technical Reports Server (NTRS)

    Salama, Ahmed; Ling, Lisa

    2005-01-01

    Vehicle breakup analysis has been performed for missions that may carry nuclear fuel for heating or power purposes to assess nuclear safety in case of launch failure leading to atmospheric reentry. Also, failure scenarios exist which could lead to breakup during Entry / Descent / Landing (EDL) at Mars due to off-nominal entries, with implications for planetary protection requirements. Since the Mars Science Laboratory (MSL) spacecraft may include a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), an analysis of breakup in case of launch failure is required. Also, breakup during Mars EDL due to off-nominal entries could release the RTG heat source that has implications for planetary protection requirements. This paper presents a methodology of MSL breakup analysis for launch failure with application to Mars off-nominal entry.

  13. 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.

  14. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  15. Orthodontics and Aligners

    MedlinePlus

    ... Repairing Chipped Teeth Teeth Whitening Tooth-Colored Fillings Orthodontics and Aligners Straighten teeth for a healthier smile. Orthodontics When consumers think about orthodontics, braces are the ...

  16. 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

  17. Tidal alignment of galaxies

    NASA Astrophysics Data System (ADS)

    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.

  18. Madelung deformity.

    PubMed

    Ghatan, Andrew C; Hanel, Douglas P

    2013-06-01

    Madelung deformity is a rare congenital anomaly of the wrist caused by asymmetric growth at the distal radial physis secondary to a partial ulnar-sided arrest. The deformity is characterized by ulnar and palmar curvature of the distal radius, positive ulnar variance, and proximal subsidence of the lunate. It more commonly occurs in females than males and typically affects both wrists. The deformity can occur in isolation or as part of a genetic syndrome. The pattern of inheritance varies, with some cases following a pseudoautosomal pattern and many others lacking a clear family history. Nonsurgical management is typically advocated in asymptomatic patients. Few studies exist on the natural history of the condition; however, extensor tendon ruptures have been reported in severe and chronic cases. Stiffness, pain, and patient concerns regarding wrist cosmesis have been cited as indications for surgery. Various techniques for surgical management of Madelung deformity have been described, but clear evidence to support the use of any single approach is lacking. PMID:23728962

  19. 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.

  20. 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.

  1. SPEAR3 Construction Alignment

    SciTech Connect

    LeCocq, Catherine; Banuelos, Cristobal; Fuss, Brian; Gaudreault, Francis; Gaydosh, Michael; Griffin, Levirt; Imfeld, Hans; McDougal, John; Perry, Michael; Rogers, Michael; /SLAC

    2005-08-17

    An ambitious seven month shutdown of the existing SPEAR2 synchrotron radiation facility was successfully completed in March 2004 when the first synchrotron light was observed in the new SPEAR3 ring, SPEAR3 completely replaced SPEAR2 with new components aligned on a new highly-flat concrete floor. Devices such as magnets and vacuum chambers had to be fiducialized and later aligned on girder rafts that were then placed into the ring over pre-aligned support plates. Key to the success of aligning this new ring was to ensure that the new beam orbit matched the old SPEAR2 orbit so that existing experimental beamlines would not have to be reoriented. In this presentation a pictorial summary of the Alignment Engineering Group's surveying tasks for the construction of the SPEAR3 ring is provided. Details on the networking and analysis of various surveys throughout the project can be found in the accompanying paper.

  2. 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.

  3. Fine structure of breakup development inferred from satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Kornilova, T. A.; Kornilov, I. A.; Kornilov, O. I.

    2008-05-01

    More than 60 breakups, including weak activations of the pseudo-breakup type, moderate breakups, and events of very strong auroral activity, were analyzed using ground-based TV data, together with satellite auroral images. We studied the fine subvisual details of spatial and temporal dynamics of active auroral forms and surrounding diffuse luminosity, both in the longitudinal and latitudinal directions of the TV camera field of view. For all types of breakups a close interconnection of auroral activity was found across and along the auroral oval.

  4. Systematical Behavior of Breakup Effects on Complete Fusion at Energies above the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Zhao, Wei-Juan; Gomes, P. R. S.; Zhao, En-Guang; Zhou, Shan-Gui

    We investigate the systematical behavior of the breakup effects on the complete fusion (CF) cross sections at energies above the Coulomb barrier. The CF cross sections are suppressed by the prompt breakup of the projectiles. This suppression effect, expressed as the ratio of the reduced fusion function and the universal fusion function (UFF), for reactions induced by the same projectile, is independent of the target and mainly determined by the lowest energy breakup channel of the projectile. There holds a good exponential relation between the suppression factor and the energy corresponding to the lowest breakup threshold.

  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. 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.

  7. 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. PMID:27018779

  8. 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.

  9. 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.

  10. Tools to Predict Beam Breakup in Recirculating Linacs

    SciTech Connect

    Kevin Beard; Nikolitsa Merminga; Byung Yunn

    2003-05-01

    An important limitation on the maximum beam current in a recirculating linac is due to beam breakup caused by higher order modes (HOM) excited in the RF cavities. A HOM delivers a transverse kick to a beam bunch, the bunch on the next pass can then drive the HOM and cause it to grow until the beam is lost. Two codes, MATBBU1 and TDBBU2, have been written to estimate the threshold current for a set of HOMs and accelerator optics. The relative merits and limitations of each is discussed in detail.

  11. Beam Breakup Studies for New Cryo-Unit

    SciTech Connect

    S. Ahmed, I. Shin, R. Kazimi, F. Marhauser ,F. Hannon ,G. Krafft ,B. Yunn ,A. Hofler

    2011-03-01

    In this paper, we report the numerical simulations of cumulative beam breakup studies for a new cryo-unit for booster design at Jefferson lab. The system consists of two 1-cell and one 7-cell superconducting RF cavities. Combining two 1-cell into a 2-cell together with a 7-cell is also an option. Simulations have been performed using the 2-dimensional time-domain code. The 1-cell+1-cell+7-cell combination confirms beam stability, however, the arrangement 2-cell+7-cell shows instability.

  12. 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.

  13. 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.

  14. Cumulative beam breakup in radio-frequency linacs

    SciTech Connect

    Bohn, C.L.; Delayen, J.R.

    1990-01-01

    An analytic model of cumulative beam breakup has been developed which is applicable to both low-velocity ion and high-energy electron linear accelerators. The model includes arbitrary velocity, acceleration, focusing, initial conditions, beam-cavity resonances, and variable cavity geometry and spacing along the accelerator. The model involves a continuum approximation'' in which the transverse kicks in momentum imparted by the cavities are smoothed over the length of the linac. The resulting equation of transverse motion is solved via the WKBJ method. Specific examples are discussed which correspond to limiting cases of the solution. 16 refs.

  15. Comparative structural reconstruction of the post-breakup succession in conjugated salt and salt-free basins offshore South-America and South-Africa

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2013-04-01

    This project focuses on the post-breakup tectono-stratigraphic development of large offshore basins along the South American and African continental margins that 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. In this study we show a regional comparison 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, etc). A sequential reconstruction of tectonic and stratigraphic elements of representative geological transects provides a comprehensive basin-to-basin documentation of the influence of key geological parameters controlling ocean and continental margin development. These include the subsidence development through time, sediment input, flux and storage patterns, salt vs. non-salt systems, carbonate-rich vs. clastics-dominated successions 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Temperature dependence of droplet breakup in 8CB and 5CB liquid crystals

    NASA Astrophysics Data System (ADS)

    Porter, Daniel; Savage, John R.; Cohen, Itai; Spicer, Patrick; Caggioni, Marco

    2012-04-01

    Droplet breakup of many Newtonian fluids is well described by current experiments, theory, and simulations. Breakup in complex fluids where interactions between mesoscopic structural features can affect the flows remains poorly understood and a burgeoning area of research. Here, we report on our investigations of droplet breakup in thermotropic liquid crystals. We investigate breakup in the smectic, nematic, and isotropic phases of 4-cyano 4-octylbiphenyl (8CB) and the nematic and isotropic phases of 4-cyano 4-pentylbiphenyl (5CB). The experiment consists of varying the ambient temperature to control liquid crystalline phase and imaging breakup using a fast video camera at up to 110000 frames/s. We expand on previous work [John R. Savage , Soft Matter1744-683X10.1039/b923069f 6, 892 (2010)] that shows breakup in the smectic phase is symmetric, producing no satellite droplets, and is well described by a similarity solution for a shear-thinning power-law fluid. We show that in the nematic phase the breakup occurs in two stages. In the first stage, the breakup is symmetric and the power-law exponent for the minimum radius dependence on the time left to breakup is 1.2breakup dynamics. Finally, in the isotropic phase, the exponents are consistent with theoretical predictions and experiments for Newtonian fluid breakup in the inertial viscous regime.

  2. Temperature dependence of droplet breakup in 8CB and 5CB liquid crystals.

    PubMed

    Porter, Daniel; Savage, John R; Cohen, Itai; Spicer, Patrick; Caggioni, Marco

    2012-04-01

    Droplet breakup of many Newtonian fluids is well described by current experiments, theory, and simulations. Breakup in complex fluids where interactions between mesoscopic structural features can affect the flows remains poorly understood and a burgeoning area of research. Here, we report on our investigations of droplet breakup in thermotropic liquid crystals. We investigate breakup in the smectic, nematic, and isotropic phases of 4-cyano 4-octylbiphenyl (8CB) and the nematic and isotropic phases of 4-cyano 4-pentylbiphenyl (5CB). The experiment consists of varying the ambient temperature to control liquid crystalline phase and imaging breakup using a fast video camera at up to 110000 frames/s. We expand on previous work [John R. Savage et al., Soft Matter 6, 892 (2010)] that shows breakup in the smectic phase is symmetric, producing no satellite droplets, and is well described by a similarity solution for a shear-thinning power-law fluid. We show that in the nematic phase the breakup occurs in two stages. In the first stage, the breakup is symmetric and the power-law exponent for the minimum radius dependence on the time left to breakup is 1.2breakup dynamics. Finally, in the isotropic phase, the exponents are consistent with theoretical predictions and experiments for Newtonian fluid breakup in the inertial viscous regime. PMID:22680486

  3. 3D thermo-mechanical models of continental breakup and transition from rifting to continental break-up and spreading

    NASA Astrophysics Data System (ADS)

    Koptev, Alexander; Burov, Evgueni; Gerya, Taras

    2014-05-01

    We conducted high-resolution 3D thermo-mechanical numerical modeling experiments to explore evolution and styles of plume-activated rifting in presence of preexisting far-field tectonic stress/strain field and tectonic heritage (in form of cratonic blocks embedded in «normal lithosphere»). The experiments demonstrate strong dependence of rifting style on preexisting far-field tectonic stress/strain field and initial thermo-rheological profile, as well as on the tectonic heritage. The models with homogeneous lithosphere demonstrate strongly non-linear impact of far-field extension rates on timing of break-up processes. Experiments with relatively fast far-field extension (6 mm/y) show intensive normal fault localization in crust and uppermost mantle above the zones of plume-head emplacement some 15-20 Myrs after the onset of the experiment. When plume head material reaches the bottom of the continental crust (at ~25 Myrs), the latter is rapidly ruptured (<1 Myrs) and several steady oceanic floor spreading centers develop. Slower (3 mm/y) far-field velocities result in disproportionally longer break-up time (from 60 to 70 Myrs depending on initial isoterm at the crust bottom). Although in all experiments with homogeneous lithosphere spreading centers have similar orientation perpendicular to the direction of far-field extension, their number and spatial location are different for different extension rates and thermo-rheological structures of the lithosphere. On the contrary, in case of normal lithosphere containing embedded cratonic block, spreading zones develop symmetrically, embracing cratonic micro-plate along its long sides. Presence of cratonic blocks leads to splitting of the plume head onto initially nearly symmetrical parts, each of which flows towards beneath the craton borders. This craton-controlled distribution of plume material causes the crustal strain localization and uprise of plume material along the craton boundaries. Though there is a net

  4. Break-up dynamics of fluctuating liquid threads.

    PubMed

    Petit, Julien; Rivière, David; Kellay, Hamid; Delville, Jean-Pierre

    2012-11-01

    The thinning dynamics of a liquid neck before break-up, as may happen when a drop detaches from a faucet or a capillary, follows different rules and dynamic scaling laws depending on the importance of inertia, viscous stresses, or capillary forces. If now the thinning neck reaches dimensions comparable to the thermally excited interfacial fluctuations, as for nanojet break-up or the fragmentation of thermally annealed nanowires, these fluctuations should play a dominant role according to recent theory and observations. Using near-critical interfaces, we here fully characterize the universal dynamics of this thermal fluctuation-dominated regime and demonstrate that the cross-over from the classical two-fluid pinch-off scenario of a liquid thread to the fluctuation-dominated regime occurs at a well-defined neck radius proportional to the thermal length scale. Investigating satellite drop formation, we also show that at the level of the cross-over between these two regimes it is more probable to produce monodisperse droplets because fluctuation-dominated pinch-off may allow the unique situation where satellite drop formation can be inhibited. Nonetheless, the interplay between the evolution of the neck profiles from the classical to the fluctuation-dominated regime and the satellites' production remains to be clarified. PMID:23090994

  5. Effects of atmospheric breakup on crater field formation. [on earth

    NASA Technical Reports Server (NTRS)

    Passey, Q. R.; Melosh, H. J.

    1980-01-01

    This paper investigates the physics of meteoroid breakup in the atmosphere and its implications for the observed features of strewn fields. There are several effects which cause dispersion of the meteoroid fragments: gravity, differential lift of the fragments, bow shock interaction just after breakup, centripetal separation by a rotating meteroid, and possibly a dynamical transverse separation resulting from the crushing deceleration in the atmosphere. Of these, it is shown that gravity alone can produce the common pattern in which the largest crater occurs at the downrange end of the scatter ellipse. The average lift-to-drag ratio of the tumbling fragments must be less than about 0.001, otherwise small fragments would produce small craters downrange of the main crater, and this is not generally observed. The cross-range dispersion is probably due to the combined effects of bow shock interaction, crushing deceleration, and possibly spinning of the meteoroid. A number of terrestrial strewn fields are discussed in the light of these ideas, which are formulated quantitatively for a range of meteoroid velocities, entry angles, and crushing strengths. It is found that when the crater size exceeds about 1 km, the separation between the fragments upon landing is a fraction of their own diameter, so that the crater formed by such a fragmented meteoroid is almost indistinguishable from that formed by a solid body of the same total mass and velocity.

  6. 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

  7. Rebound sex: Sexual motives and behaviors following a relationship breakup.

    PubMed

    Barber, Lindsay L; Cooper, M Lynne

    2014-02-01

    The present study used a longitudinal, online diary method to examine trajectories of psychological recovery and sexual experience following a romantic relationship breakup among 170 undergraduate students. Consistent with popular beliefs about rebound and revenge sex, having sex to cope with distress and to get over or get back at the ex-partner were elevated immediately following the breakup and then declined over time, as did the probability of having sex with a new partner. Also consistent with popular lore, those who were "dumped" by their partners were more distressed and angry and more likely to have sex to cope and to get back at or get over their ex-partner. Finally, individuals who reported having sex to cope with negative feelings or to get over their ex-partner at the beginning of the study were more likely to have sex with a stranger and to continue having sex with new partners over time. Results were discussed in terms of widely held but largely untested beliefs about rebound and revenge sex. PMID:24356947

  8. Mechanism of flow-induced biomolecular and colloidal aggregate breakup

    NASA Astrophysics Data System (ADS)

    Conchúir, Breanndán Ó.; Zaccone, Alessio

    2013-03-01

    The drift-diffusion equation is first solved analytically for the dissociation rate and lifetime of a biomolecular or colloidal dimer bonded by realistic intermolecular potentials, under shear flow. Then we show using rigidity percolation concepts that the lifetime of a generic cluster formed under shear is controlled by the typical lifetime of a single bond in its interior. The latter, however, is also affected by collective stress transmission from other bonds in the aggregate, which we account for by introducing a semiempirical, analytical stress transmission efficiency 0⩽Γ⩽1 calibrated on several simulation data sets. We show that aggregate breakup is a thermally activated process in which the activation energy is controlled by the interplay between intermolecular forces and the shear drift. The collective contribution to the overall shear drift term is dominant for large enough fractal aggregates, while surface erosion prevails for small and compact aggregates. The crossover between the two regimes occurs when ΓN≃2, where both the number of particles in the cluster N and the stress transmission efficiency Γ depend on the aggregate structure through the fractal dimension df. The analytical framework for the aggregate breakup rate is in quantitative agreement with experiments and can be used in future studies in the population balance modeling of colloidal and protein aggregation.

  9. 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

  10. 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

  11. Distribution of living Cupressaceae reflects the breakup of Pangea.

    PubMed

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

    2012-05-15

    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

  12. Antares alignment gimbal positioner

    SciTech Connect

    Day, R.D.; Viswanathan, V.K.; Saxman, A.C.; Lujan, R.E.; Woodfin, G.L.; Sweatt, W.C.

    1981-01-01

    Antares is a 24-beam 40-TW carbon-dioxide (CO/sub 2/) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, and wavefront optical path difference, as well as aberration information at both helium-neon (He-Ne) and CO/sub 2/ wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1-cm cube to a tolerance of 10 ..mu..m.

  13. EINSTEIN Cluster Alignments Revisited

    NASA Astrophysics Data System (ADS)

    Chambers, S. W.; Melott, A. L.; Miller, C. J.

    2000-12-01

    We have examined whether the major axes of rich galaxy clusters tend to point (in projection) toward their nearest neighboring cluster. We used the data of Ulmer, McMillan and Kowalski, who used x-ray morphology to define position angles. Our cluster samples, with well measured redshifts and updated positions, were taken from the MX Northern Abell Cluster Survey. The usual Kolmogorov-Smirnov test shows no significant alignment signal for nonrandom angles for all separations less than 100 Mpc/h. Refining the null hypothesis, however, with the Wilcoxon rank-sum test, reveals a high confidence signal for alignment. This confidence is highest when we restrict our sample to small nearest neighbor separations. We conclude that we have identified a more powerful tool for testing cluster-cluster alignments. Moreover, there is a strong signal in the data for alignment, consistent with a picture of hierarchical cluster formation in which matter falls into clusters along large scale filamentary structures.

  14. Pairwise Sequence Alignment Library

    Energy Science and Technology Software Center (ESTSC)

    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 footprintmore » 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.« less

  15. 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.

  16. Predicting Fall Semester Breakups in College Roommates: A Replication Using the Social Satisfaction Questionnaire.

    ERIC Educational Resources Information Center

    Lovejoy, M. Christine; And Others

    1995-01-01

    Undergraduates living in residence halls (n=578) completed the Social Satisfaction Questionnaire (SSQ). SSQ scores predicted subsequent roommate breakups resulting from interpersonal conflict. The prediction of breakup provided by SSQ scores was superior to that for demographic variables, other indices of the relationship quality, and general…

  17. Numerical simulation of particle fluxes formation generated as a result of space objects breakups in orbit

    NASA Astrophysics Data System (ADS)

    Aleksandrova, A. G.; Galushina, T. Yu.

    2015-12-01

    The paper describes the software package developed for the numerical simulation of the breakups of natural and artificial objects and algorithms on which it is based. A new software "Numerical model of breakups" includes models of collapse of the spacecraft (SC) as a result of the explosion and collision as well as two models of the explosion of an asteroid.

  18. 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

  19. Breakup of shearless invariant tori in cubic and quartic nontwist maps

    NASA Astrophysics Data System (ADS)

    Wurm, A.; Fuchss Portela, K.

    2012-05-01

    The effect of symmetry on invariant torus breakup in nontwist maps is investigated. In particular, the breakup of shearless invariant tori with winding number ω=(√{5}-1)/2 (inverse golden mean) and ω=√{2}-1 (an inverse silver mean) is studied numerically using Greene's residue criterion in a cubic and a quartic nontwist map. The details of the breakup are compared to those previously obtained for the standard nontwist map, which has the same particular spatial symmetry as the quartic map. The cubic map lacks this symmetry. The results show that if the symmetry exists, the details of the breakup are the same as in the standard nontwist map. If the symmetry does not exist, the breakup is shown to be different.

  20. 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.

  1. Effect of the breakup context on unwanted pursuit behavior perpetration between former partners.

    PubMed

    De Smet, Olivia; Buysse, Ann; Brondeel, Ruben

    2011-07-01

    Former partners comprise the most important subgroup of stalkers. However, contextual factors related to the breakup are hardly examined to explain ex-partner pursuit. In a community sample of 194 separated persons, about one-fifth perpetrated at least one unwanted pursuit behavior in the past 2 weeks. Being female, lowly educated, and socially undesirable raised the number of perpetrated behaviors. Beyond these effects, the number of behaviors increased when the cause of the break was attributed to the ex-partner or external factors and when the ex was appraised as the breakup initiator. Breakup reasons, the ex-partner's lack in meeting family obligations and own infidelity, also related to pursuit behaviors albeit inferior to subjective attributions and appraisals of initiation. Finally, participants who felt more anxious or lonely negative showed more behaviors. The results enlighten that the breakup context gains further attention. Clinical treatment might benefit from fostering cognitive reconstructions and breakup adjustment. PMID:21470223

  2. 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.

  3. 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…

  4. 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

  5. Modeling mud flocculation using variable collision and breakup efficiencies

    NASA Astrophysics Data System (ADS)

    Strom, K.; Keyvani, A.

    2013-12-01

    Solution of the Winterwerp (1998) floc growth and breakup equation yields time dependent median floc size as an outcome of collision driven floc growth and shear induced floc breakage. The formulation is quite nice in that it is an ODE that yields fast solution for median floc size and can be incorporated into sediment transport models. The Winterwerp (1998) floc size equation was used to model floc growth and breakup data from laboratory experiments conducted under both constant and variable turbulent shear rate (Keyvani 2013). The data showed that floc growth rate starts out very high and then reduces with size to asymptotically approach an equilibrium size. In modeling the data, the Winterwerp (1998) model and the Son and Hsu (2008) variant were found to be able to capture the initial fast growth phase and the equilibrium state, but were not able to well capture the slow growing phase. This resulted in flocs reaching the equilibrium state in the models much faster than the experimental data. The objective of this work was to improve the ability of the general Winterwerp (1998) formulation to better capture the slow growth phase and more accurately predict the time to equilibrium. To do this, a full parameter sensitivity analysis was conducted using the Winterwerp (1998) model. Several modifications were tested, including the variable fractal dimension and yield strength extensions of Son and Hsu (2008, 2009). The best match with the in-house data, and data from the literature, was achieved using floc collision and breakup efficiency coefficients that decrease with floc size. The net result of the decrease in both of these coefficients is that floc growth slows without modification to the equilibrium size. Inclusion of these new functions allows for substantial improvement in modeling the growth phase of flocs in both steady and variable turbulence conditions. The improvement is particularly noticeable when modeling continual growth in a decaying turbulence field

  6. Derivation of breakup probabilities of weakly bound nuclei from experimental elastic and quasi-elastic scattering angular distributions

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Diaz-Torres, A.; Gomes, P. R. S.; Lenske, H.

    2015-11-01

    We present a simple method to derive breakup probabilities of weakly bound nuclei by measuring only elastic (or quasi-elastic) scattering for the system under investigation and a similar tightly bound system. When transfer followed by breakup is an important process, one can derive only the sum of breakup and transfer probabilities.

  7. Elastic scattering, fusion, and breakup of light exotic nuclei

    NASA Astrophysics Data System (ADS)

    Kolata, J. J.; Guimarães, V.; Aguilera, E. F.

    2016-05-01

    The present status of fusion reactions involving light ( A < 20) radioactive projectiles at energies around the Coulomb barrier ( E < 10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron- and proton-rich systems. Possible physical explanations for the observed differences are also reviewed.

  8. Breakup of partially wetting nanoscale nematic liquid films

    NASA Astrophysics Data System (ADS)

    Lam, Michael; Linda Cummings Collaboration; Lou Kondic Collaboration; Te-Sheng Lin Collaboration

    2015-11-01

    The breakup of nematic liquid crystals (NLCs) films with thicknesses less than a micrometer is studied. Particular attention is paid to the interplay between the bulk elasticity and the anchoring (boundary) conditions at the substrate and free surface. Within the framework of the long wave approximation, a fourth order nonlinear partial differential equation (PDE) is derived for the free surface height. Numerical simulations of a perturbed flat film show that, depending on the initial average thickness of the film, satellite droplets form and persist on time scales much longer than dewetting. Formulating the model in terms of an effective disjoining pressure (elastic response and van der Waals interaction), simulations further suggest that satellite droplets form when the initial average film thickness corresponds to a positive effective disjoining pressure. Our results may shed light on the so-called ''forbidden film thicknesses'' seen in experiments. Supported by NSF grant DMS-1211713.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Single particles accelerate final stages of capillary break-up

    NASA Astrophysics Data System (ADS)

    Lindner, Anke; Fiscina, Jorge Eduardo; Wagner, Christian

    2015-06-01

    Droplet formation of suspensions is present in many industrial and technological processes such as coating and food engineering. Whilst the finite-time singularity of the minimum neck diameter in capillary break-up of simple liquids can be described by well-known self-similarity solutions, the pinching of non-Brownian suspension depends in a complex way on the particle dynamics in the thinning thread. Here we focus on the very dilute regime where the filament contains only isolated beads to identify the physical mechanisms leading to the pronounced acceleration of the filament thinning observed. This accelerated regime is characterized by an asymmetric shape of the filament with an enhanced curvature that depends on the size and the spatial distribution of the particles within the capillary thread.

  14. Large eddy breakup devices as low Reynolds number airfoils

    NASA Technical Reports Server (NTRS)

    Anders, John B.

    1986-01-01

    Turbulent drag reduction downstream of large-eddy breakup (LEBU) devices is analyzed from the viewpoint of low-Reynolds number airfoil aerodynamics. It is argued that the variability of results between different research labs is primarily due to low Reynolds number 'phenomena' associated with unsteady separation/transition of the LEBU device boundary layer. LEBU drag reduction is shown to be an extremely sensitive function of device microgeometry at the low Reynolds numbers of all current investigations, and by analogy with conventional low-Reynolds number airfoil testing, the conclusion is drawn that the full potential for LEBU drag reduction must be explored at chord Reynolds numbers of 300,000 and above.

  15. 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.

  16. Polar lake circulation during ice break-up

    NASA Astrophysics Data System (ADS)

    Kirillin, Georgiy; Forrest, Alexander; Graves, Kelly; Laval, Bernard

    2014-05-01

    An extensive dataset on lake physical properties has been collected during the final stage of the ice-covered period in May-June 2013 in polar Lake Kilpisjärvi, Finland. The data reveal several important features of lake dynamics, which shed new light on the mechanism of ice cover break-up and ice melting in lakes and marginal seas. CTD transects with high spatial resolution showed up a 300m-wide upwelling zone in the center of the lake, driven by downslope converging flow of warm waters from open-water 'moat' along the lake shoreline. The resulting radial density gradient, balanced by the Coriolis force, created a lake-wide anti-cyclonically rotating gyre with a measured peak azimuthal velocity of 0.05 m/s. Appreciable marginal heating is driven in polar enclosed basins by high amount of solar radiation and by surface inflow of meltwater. Hence, quasi-geostrophic anticyclonic circulation is suggested to be a general feature of polar lakes, redistributing heat within a water body and potentially accelerating ice melting. In addition, high-resolution records of pressure, current velocities and water temperature revealed under-ice seiches with periods of 10 to 25 min. The ice breakup was associated with 10 times increase of seiche amplitudes under ice. The seiches decayed within 10-15 hours; during this short period, the previously ice-covered lake became ice-free. We suggest that seiche-driven vertical motions of the soft ice sheet contribute significantly to breaking and melting of seasonal ice in enclosed reservoirs.

  17. The dynamics of Persistent Cold-Air Pool breakup

    NASA Astrophysics Data System (ADS)

    Lareau, Neil P.

    The wind-induced disruption and breakup of multiday cold-air pools are investigated using observational analyses and idealized numerical simulations. The observations are from the Persistent Cold-Air Pool (CAP) Study, which provides modern measurement of the meteorological processes affecting the duration of cold-air pools in the Salt Lake Valley of Utah. In general, the observations indicate that synoptic-scale processes control cold-air pool duration while local processes affect near-surface stratification and mixing. The most common form of CAP breakup is due to cold-air advection aloft. However, analyses reveal that some cold-air pools are destroyed or disrupted by strong winds penetrating into the valley. The resulting wind-CAP interactions are complex, involving sequential CAP displacements, internal oscillations, dynamic instabilities, and terrain-flow interactions. Large Eddy Simulations of multiday cold-air pools in idealized valley topography further demonstrate that cold-air pool removal is affected by the interplay of Kelvin-Helmholtz instability and warm air advection. This dynamic instability generates breaking waves in the stratified shear flow that mix cold-air into the warmer flow aloft. Variations in the initial cold pool stratification and valley terrain affect the timescale for cold-air pool removal. Despite these variations, a basic relationship between the magnitude of the flow aloft and the strength of the underlying cold-air pool can be expressed in terms of the "CAP Froude number." This dimensionless quantity is useful for diagnosing the onset and amplification of turbulent mixing, as well as the complete removal of cold-air pools.

  18. Alignment and nonlinear elasticity in biopolymer gels

    NASA Astrophysics Data System (ADS)

    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.

  19. FMIT alignment cart

    SciTech Connect

    Potter, R.C.; Dauelsberg, L.B.; Clark, D.C.; Grieggs, R.J.

    1981-01-01

    The Fusion Materials Irradiation Test (FMIT) Facility alignment cart must perform several functions. It must serve as a fixture to receive the drift-tube girder assembly when it is removed from the linac tank. It must transport the girder assembly from the linac vault to the area where alignment or disassembly is to take place. It must serve as a disassembly fixture to hold the girder while individual drift tubes are removed for repair. It must align the drift tube bores in a straight line parallel to the girder, using an optical system. These functions must be performed without violating any clearances found within the building. The bore tubes of the drift tubes will be irradiated, and shielding will be included in the system for easier maintenance.

  20. Barrel alignment fixture

    NASA Astrophysics Data System (ADS)

    Sheeley, J. D.

    1981-04-01

    Fabrication of slapper type detonator cables requires bonding of a thin barrel over a bridge. Location of the barrel hole with respect to the bridge is critical: the barrel hole must be centered over the bridge uniform spacing on each side. An alignment fixture which permits rapid adjustment of the barrel position with respect to the bridge is described. The barrel is manipulated by pincer-type fingers which are mounted on a small x-y table equipped with micrometer adjustments. Barrel positioning, performed under a binocular microscopy, is rapid and accurate. After alignment, the microscope is moved out of position and an infrared (IR) heat source is aimed at the barrel. A 5-second pulse of infrared heat flows the adhesive under the barrel and bonds it to the cable. Sapphire and Fotoform glass barrels were bonded successfully with the alignment fixture.

  1. 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.

  2. 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.

  3. 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.

  4. Orientation and Alignment Echoes

    NASA Astrophysics Data System (ADS)

    Karras, G.; Hertz, E.; Billard, F.; Lavorel, B.; Hartmann, J.-M.; Faucher, O.; Gershnabel, Erez; Prior, Yehiam; Averbukh, Ilya Sh.

    2015-04-01

    We present one of the simplest classical systems featuring the echo phenomenon—a collection of randomly oriented free rotors with dispersed rotational velocities. Following excitation by a pair of time-delayed impulsive kicks, the mean orientation or alignment of the ensemble exhibits multiple echoes and fractional echoes. We elucidate the mechanism of the echo formation by the kick-induced filamentation of phase space, and provide the first experimental demonstration of classical alignment echoes in a thermal gas of CO2 molecules excited by a pair of femtosecond laser pulses.

  5. Segment alignment control system

    NASA Technical Reports Server (NTRS)

    Aubrun, JEAN-N.; Lorell, Ken R.

    1988-01-01

    The segmented primary mirror for the LDR will require a special segment alignment control system to precisely control the orientation of each of the segments so that the resulting composite reflector behaves like a monolith. The W.M. Keck Ten Meter Telescope will utilize a primary mirror made up of 36 actively controlled segments. Thus the primary mirror and its segment alignment control system are directly analogous to the LDR. The problems of controlling the segments in the face of disturbances and control/structures interaction, as analyzed for the TMT, are virtually identical to those for the LDR. The two systems are briefly compared.

  6. 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.

  7. 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.

  8. Disintegration locations in 7Li→8Be transfer-triggered breakup at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Simpson, E. C.; Cook, K. J.; Luong, D. H.; Kalkal, Sunil; Carter, I. P.; Dasgupta, M.; Hinde, D. J.; Williams, E.

    2016-02-01

    Background: At above-barrier energies, complete fusion cross sections in collisions of light weakly bound nuclei with heavy target nuclei are suppressed when compared to well-bound nuclei. Breakup of the projectilelike nucleus was proposed to be the cause. In addition to direct breakup, breakup following transfer was shown to be substantial. Purpose: We investigate breakup in reactions with 7Li, triggered by sub-barrier proton pickup to unbound states in 8Be, which subsequently separate into two α particles. Method: Measurements of sub-barrier disintegration of 7Li on a 58Ni target were made using the Heavy Ion Accelerator Facility at the Australian National University. Combining the experimental results with classical simulations of post-breakup acceleration, we study the sensitivity of α -α energy and angle correlations to the proximity of disintegration to the target (proton donor) nucleus. Results: The simulations indicate that disintegration as the colliding nuclei approach each other leads to large angular separations θ12 of the α fragments. The detectors allow for a maximum opening angle of θ12=132∘ , such that the present experiment is largely insensitive to breakup occurring when the collision partners approach each other. The data are consistent with disintegration of (a) the 0+8Be ground state far from the targetlike nucleus, and (b) the 2+8Be resonance near the targetlike nucleus when the 8Be is receding from the targetlike nucleus. Conclusions: The present results shed light on the near-target component of transfer-induced breakup reactions. The distribution of events with respect to the opening angle of the α particles, and the orientation of their relative velocity with respect to the velocity of their center of mass, gives insights into their proximity to the target at the moment of breakup. Further measurements with larger angular coverage and more complete simulations are required to fully understand the influence of breakup on fusion.

  9. Spatial and temporal patterns in Arctic river ice breakup revealed by automated ice detection from MODIS imagery

    NASA Astrophysics Data System (ADS)

    Cooley, Sarah; Pavelsky, Tamlin

    2016-04-01

    The annual spring breakup of river ice has important consequences for northern ecosystems and significant economic implications for Arctic industry and transportation. River ice breakup research is restricted by the sparse distribution of hydrological stations in the Arctic, where limited available data suggests a trend towards earlier ice breakup. The specific climatic mechanisms driving this trend, however, are complex and can vary both regionally and within river systems. Consequently, understanding the response of river ice processes to a warming Arctic requires simultaneous examination of spatial and temporal patterns in breakup timing. Here we present an automated algorithm for river ice breakup detection using MODIS satellite imagery that enables identification of spatial and temporal breakup patterns at large scales. We examine breakup timing on the Mackenzie, Lena, Ob' and Yenisey rivers for the period 2000-2014. First, we split each river into 10 km segments. Next, for each day of the breakup season, we classify each river pixel as snow/ice, mixed ice/water or open water based on MODIS reflectance values and remove all cloud-covered segments using the MODIS cloud product. We then define the breakup date as the first day where the segment is 75% open water. Using this method, we are able to determine breakup dates with a mean uncertainty of +/-1.3 days. We find our remotely sensed breakup dates to be highly correlated to ground breakup dates and the timing of peak discharge. All statistically significant temporal trends in breakup timing are negative, indicating an overall shift towards earlier breakup. Considerable variability in the statistical significance and magnitude of trends along each river suggests that different climatic and physiographic drivers are impacting spatial patterns in breakup. Trends detected on the lower Mackenzie corroborate recent studies indicating weakening ice resistance and earlier breakup timing near the Mackenzie Delta. In

  10. Vertical Alignment and Collaboration.

    ERIC Educational Resources Information Center

    Bergman, Donna; Calzada, Lucio; LaPointe, Nancy; Lee, Audra; Sullivan, Lynn

    This study investigated whether vertical (grade level sequence) alignment of the curriculum in conjunction with teacher collaboration would enhance student performance on the Texas Assessment of Academic Skills (TAAS) test in south Texas school districts of various sizes. Surveys were mailed to the office of the superintendent of 47 school…

  11. 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…

  12. 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

  13. 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…

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. No-capture breakup and incomplete fusion reactions induced by stable weakly bound nucleus 9Be

    NASA Astrophysics Data System (ADS)

    Seyyedi, S. A.

    2016-06-01

    The reactions including the stable weakly bound nucleus 9Be have been studied using the classical trajectory model accompanied with the experimental breakup function and the Aage-Winther interaction potential (AW95). In these calculations, the no-capture breakup and the incomplete fusion cross-sections as well as their competition at around the Coulomb barrier have been investigated. Our calculations showed that at a given far-Coulomb-barrier energy the incomplete fusion reaction in different distributions of angular momentum and energies can dominate the no-capture breakup reaction. This dominating process is reversed at the near-barrier energies.

  19. Recent Advances in Nuclear Reaction Theories for Weakly Bound Nuclei: Reexamining the Problem of Inclusive Breakup

    NASA Astrophysics Data System (ADS)

    Moro, Antonio M.; Lei, Jin

    2016-05-01

    The problem of the calculation of inclusive breakup cross sections in nuclear reactions is reexamined. For that purpose, the theory proposed by Ichimura et al. (Phys Rev C 32:431, 1985) is revisited, both in its prior and post representations. We briefly outline the connection of this theory with that proposed by Udagawa and Tamura (Phys Rev C 24:1348, 1981) and apply both theories to the inclusive breakup of ^6Li on ^{209}Bi at near-barrier energies, comparing also with available data. The relative importance of elastic versus non-elastic breakup, as a function of the incident energy and of the projectile separation energy, is also investigated.

  20. Spin alignment of excited projectiles due to target spin-flip interactions

    NASA Astrophysics Data System (ADS)

    Charity, R. J.; Elson, J. M.; Manfredi, J.; Shane, R.; Sobotka, L. G.; Chajecki, Z.; Coupland, D.; Iwasaki, H.; Kilburn, M.; Lee, Jenny; Lynch, W. G.; Sanetullaev, A.; Tsang, M. B.; Winkelbauer, J.; Youngs, M.; Marley, S. T.; Shetty, D. V.; Wuosmaa, A. H.

    2015-02-01

    The sequential breakup of E /A =65.5 -MeV7Be and E /A =36.6 -MeV6Li projectiles excited through inelastic interactions with 9Be target nuclei has been studied. For events where the target nucleus remained in its ground state, significant alignment of the excited projectile's spin axis parallel or antiparallel to the beam direction was observed. This unusual spin alignment was found to be largely independent of the projectile's scattering angle and it was deduced that the target nucleus has a significant probability of changing its spin orientation during the interaction. It is proposed that the unusual spin alignment is a consequence of the molecular structure of the 9Be nucleus.

  1. 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.

  2. 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.

  3. Role of neutron transfer and deformation effect in capture process at sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Scheid, W.; Zhang, H. Q.

    2012-12-01

    The roles of nuclear deformation and neutron transfer in sub-barrier capture process are studied within the quantum diffusion approach. The change of the deformations of colliding nuclei with neutron exchange can crucially influence the sub-barrier fusion. The sub-barrier capture reactions following the neutron pair transfer are used for the indirect study of neutron-neutron correlation in the surface region of nucleus. The strong surface enhancement of the neutron pairing in nuclei 48Ca, 64Ni, and 116,124,132Sn is demonstrated. Comparing the capture cross sections calculated without the breakup effect and experimental complete fusion cross sections, the breakup was analyzed in reactions with weakly bound projectiles 6,7,9Li and 9Be. A trend of a systematic behavior for the complete fusion suppression as a function of the target charge and bombarding energy is not achieved.

  4. Deformation of vortex patches by boundaries

    NASA Astrophysics Data System (ADS)

    Crosby, A.; Johnson, E. R.; Morrison, P. J.

    2013-02-01

    The deformation of two-dimensional vortex patches in the vicinity of fluid boundaries is investigated. The presence of a boundary causes an initially circular patch of uniform vorticity to deform. Sufficiently far away from the boundary, the deformed shape is well approximated by an ellipse. This leading order elliptical deformation is investigated via the elliptic moment model of Melander, Zabusky, and Styczek [J. Fluid Mech. 167, 95 (1986), 10.1017/S0022112086002744]. When the boundary is straight, the centre of the elliptic patch remains at a constant distance from the boundary, and the motion is integrable. Furthermore, since the straining flow acting on the patch is constant in time, the problem is that of an elliptic vortex patch in constant strain, which was analysed by Kida [J. Phys. Soc. Jpn. 50, 3517 (1981), 10.1143/JPSJ.50.3517]. For more complicated boundary shapes, such as a square corner, the motion is no longer integrable. Instead, there is an adiabatic invariant for the motion. This adiabatic invariant arises due to the separation in times scales between the relatively rapid time scale associated with the rotation of the patch and the slower time scale associated with the self-advection of the patch along the boundary. The interaction of a vortex patch with a circular island is also considered. Without a background flow, the conservation of angular impulse implies that the motion is again integrable. The addition of an irrotational flow past the island can drive the patch towards the boundary, leading to the possibility of large deformations and breakup.

  5. Effectiveness of Using Fewer Implanted Fiducial Markers for Prostate Target Alignment

    SciTech Connect

    Kudchadker, Rajat J. Lee, Andrew K.; Yu Zhiqian; Johnson, Jennifer L.; Zhang Lifei; Zhang Yongbin; Amos, Richard A.; Nakanishi, Hiroyuki; Ochiai, Atsushi; Dong Lei

    2009-07-15

    Purpose: To evaluate the impact of the number and location of intraprostatic fiducial markers on the accuracy and reproducibility of daily prostate target alignment and to evaluate the migration of such markers. Methods and Materials: Three gold fiducial markers were implanted transrectally under ultrasound guidance near the apex, middle, and base of the prostate in 10 prostate cancer patients. The patients had pretreatment in-room computed tomography (CT) scans three times a week, for approximately 25 CT scans per patient during the 8-week treatment course. A total of 1280 alignments were performed using different alignment scenarios: whole-prostate soft tissue alignment (the gold standard), bone alignment, and seven permutations of alignments using one, two, or three fiducial markers. The results of bone alignment and fiducial alignment were compared with the results of whole-prostate alignment. Fiducial migration was also evaluated. Results: Single-fiducial-marker alignment was more accurate and reproducible than bone alignment. However, due to organ deformation, single fiducial markers did not always reliably represent the position of the entire prostate. The use of two-fiducial combinations was more accurate and reproducible than single-fiducial alignment, and use of all three fiducials was the best. Use of an apex fiducial together with a base fiducial rivaled the use of all three fiducials markers together. Fiducial migration was minimal. Conclusions: The number and the location of implanted fiducial markers affect the accuracy and reliability of daily prostate target alignment. The use of two or more fiducial markers is recommended.

  6. 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

  7. 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

  8. Experimental signatures for distinguishing breakup fusion and transfer in {sup 7}Li+{sup 165}Ho

    SciTech Connect

    Tripathi, V.; Navin, A.; Mahata, K.; Ramachandran, K.; Shrivastava, A.; Chatterjee, A.; Kailas, S.; Nanal, V.; Pillay, R.G.

    2005-07-01

    Reactions involving weakly bound nuclei of {sup 7}Li show large yields of {alpha} particles that have their origin in elastic breakup, breakup followed by fusion, or triton transfer. The latter two processes, breakup fusion and transfer, have similar characteristics and produce the same residual fragments. We report here results of exclusive measurements of charged particles and characteristic {gamma} rays from the heavy residues in the {sup 7}Li+{sup 165}Ho system at 42 MeV (E/V{sub b}{approx_equal}1.6) to look for experimental signatures to differentiate between transfer and breakup fusion. Such a distinction is essential for a better theoretical understanding of both the fusion process and direct reactions involving weakly bound stable and unstable beams.

  9. Multipass beam breakup in the CEBAF (Continuous Electron Beam Accelerator Facility) superconducting linac

    SciTech Connect

    Bisognano, J.J.; Krafft, G.A.

    1986-06-02

    Multipass beam breakup can severely limit current in superconducting linear accelerators due to the inherently high Q's of transverse deflecting modes of the rf cavities. The success of higher-order-mode damping in increasing threshold currents for the 4-pass CEBAF SRF linac design is investigated with computer modeling. This simulation is shown to be in agreement with theoretical analyses which have successfully described beam breakup in the Stanford superconducting, recirculating linac. Numerical evaluation of an analytic treatment by Gluckstern of multipass beam breakup with distributed cavities is also found to be consistent with the computer model. Application of the simulation to the design array of 400 five-cell CEBAF/Cornell cavities with measured higher-order-mode damping indicates that the beam breakup threshold current is at least an order of magnitude above the CEBAF design current of 200 ..mu..A.

  10. 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.

  11. 11Li Breakup on 208 at energies around the Coulomb barrier.

    PubMed

    Fernández-García, J P; Cubero, M; Rodríguez-Gallardo, M; Acosta, L; Alcorta, M; Alvarez, M A G; Borge, M J G; Buchmann, L; Diget, C A; Falou, H A; Fulton, B R; Fynbo, H O U; Galaviz, D; Gómez-Camacho, J; Kanungo, R; Lay, J A; Madurga, M; Martel, I; Moro, A M; Mukha, I; Nilsson, T; Sánchez-Benítez, A M; Shotter, A; Tengblad, O; Walden, P

    2013-04-01

    The inclusive breakup for the (11)Li + (208)Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of (9)Li following the (11)Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the (11)Li continuum at low excitation energy. PMID:25166983

  12. 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).

  13. 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

  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. 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.

  16. Alignments of RNA structures.

    PubMed

    Blin, Guillaume; Denise, Alain; Dulucq, Serge; Herrbach, Claire; Touzet, Hélène

    2010-01-01

    We describe a theoretical unifying framework to express the comparison of RNA structures, which we call alignment hierarchy. This framework relies on the definition of common supersequences for arc-annotated sequences and encompasses the main existing models for RNA structure comparison based on trees and arc-annotated sequences with a variety of edit operations. It also gives rise to edit models that have not been studied yet. We provide a thorough analysis of the alignment hierarchy, including a new polynomial-time algorithm and an NP-completeness proof. The polynomial-time algorithm involves biologically relevant edit operations such as pairing or unpairing nucleotides. It has been implemented in a software, called gardenia, which is available at the Web server http://bioinfo.lifl.fr/RNA/gardenia. PMID:20431150

  17. On the alignment space.

    PubMed

    Shen, Shi-Yi; Wang, Kui; Hu, Gang; Chen, Lu-Sheng; Zhang, Hua; Xia, Shu-Tao

    2005-01-01

    Sequences with generalized errors which are called mutations in bioinformatics and generalized error-correcting codes are studied in this paper. In the areas of bioinformatics, computer science and information theory, sequences with generalized errors are discussed respectively for different aims. Firstly, we give the definitions of alignment distance and Levenshtein distance by expansion sequences and discuss their properties and relations. Then the modular structure theory is introduced for strictly describe the expansion sequences. We show that the expansion modular structures of sequences form a Boolean algebra. As applications of the modular structure theory, we give a new and more strict proof of triangle inequality for alignment distance. At last, the definition and construction of generalized error-correcting codes are studied, and some optimal codes with small length are listed. PMID:17282158

  18. Breakup of inverse golden mean shearless tori in the two-frequency standard nontwist map

    NASA Astrophysics Data System (ADS)

    Wurm, A.; Martini, K. M.

    2013-03-01

    The breakup of shearless invariant tori with winding number ω=(√{5}-1)/2 (inverse golden mean) is studied using Greene's residue criterion in the recently derived two-frequency or extended standard nontwist map (ESNM). Depending on the frequency ratio, the ESNM has or does not have a particular spatial symmetry. If the symmetry is present, the breakup is shown to be the same as in the standard nontwist map; if not, the results are very different.

  19. Measuring the area of tear film break-up by image analysis software

    NASA Astrophysics Data System (ADS)

    Pena-Verdeal, Hugo; García-Resúa, Carlos; Ramos, Lucía.; Mosquera, Antonio; Yebra-Pimentel, Eva; Giráldez, María. Jesús

    2013-11-01

    Tear film breakup time (BUT) test only examines the first break in the tear film, but subsequent tear film events are not monitored. We present a method of measuring the area of breakup after the appearance of the first breakup by using open source software. Furthermore, the speed of the rupture was determined. 84 subjects participated in the study. 2 μl volume of 2% sodium fluorescein was instilled using a micropipette. The subject was seated behind a slit-lamp using a cobalt blue filter together with a Wratten 12 yellow filter. Then, the tear film was recorded by a camera attached to the slit lamp. 4 frames of each video was extracted, the first rupture (BUT_0), breakup after 1 second (BUT_1), rupture after 2 seconds (BUT_2) and breakup before the last blink (BUT_F). Open source software of measurement based on Java (NIH ImageJ) was used to measure the number of pixels in areas of breakup. These areas were divided by the area of exposed cornea to obtain the percentage of ruptures. Instantaneous breakup speed was calculated for second 1 as the difference between BUT_1 - BUT_0, whereas instant speed for second 2 was BUT_2 - BUT_1. Mean area of breakup obtained was: BUT_0 = 0.26%, BUT_1 = 0.48%, BUT_2 = 0.79% and BUT_F = 1.61%. Break speed was 0.22 area/sec for second 1 and 0.31 area/sec for second 2, showing a statistical difference between them (p = 0.007). Post BUT analysis may be easily monitoring with the aid of this software.

  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. 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.

  2. Nuclear reactor alignment plate configuration

    DOEpatents

    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.

  3. Remnants of an Ancient Ocean-Continent Transition Exposed in the Alps: A Window for Understanding Break-up Processes

    NASA Astrophysics Data System (ADS)

    Manatschal, G.

    2005-05-01

    . This deformation was acquired during their intrusion into partially serpentinized mantle rocks and subsequent exhumation. U/Pb on zircon and Ar/Ar on phlogopite ages obtained from these gabbros, interpreted as crystallization and cooling ages respectively, range between 165 and 157 Ma, which corresponds to the age of radiolarian cherts, the first sediments sealing oceanic and continental units in the OCT. The occurrence of isolated allochthons of continental origin stranded onto subcontinental mantle is incompatible with mantle exhumation at a mid-ocean ridge. Therefore, the detachment system preserved in the Alps is more likely related to final rifting leading to break-up and onset of seafloor spreading. All observations reported from the Alpine analogues reveal that the detachment system formed as a downward concave fault in a previously rifted crust that was already thinned to less than 10 km, and that serpentinization and magmatic activity were closely related to detachment faulting. Therefore, the thinning of the crust to 10 km and the localization of rifting within the area of final break-up can not be explained by magmatic and/or serpentinization processes, but may be predetermined by inherited heterogeneities within the pre-rift lithosphere. The interaction of tectonic, magmatic and hydrothermal processes during final break-up may explain the previously enigmatic final stage of continental extension and onset of seafloor spreading in magma-poor systems, which appears to be dominated by downward concave faulting.

  4. Effect of gas mass flux on cryogenic liquid jet breakup

    NASA Astrophysics Data System (ADS)

    Ingebo, R. D.

    A scattered-light scanning instrument developed at NASA Lewis Research Center was used to measure the characteristic drop size of clouds of liquid nitrogen droplets. The instrument was calibrated with suspensions of monosized polystyrene spheres. In this investigation of the mechanism of liquid nitrogen jet disintegration in a high-velocity gas flow, the Sauter mean diameter, D32, was found to vary inversely with the nitrogen gas mass flux raised to the power 1.33. Values of D32 varied from 5 to 25 microns and the mass flux exponent of 1.33 agrees well with theory for liquid jet breakup in high-velocity gas flows. The loss of very small droplets due to the high vaporization rate of liquid nitrogen was avoided by sampling the spray very close to the atomizer, i.e., 1.3 cm downstream of the nozzle orifice. The presence of high velocity and thermal gradients in the gas phase also made sampling of the particles difficult. As a result, it was necessary to correct the measurements for background noise produced by both highly turbulent gas flows and thermally induced density gradients in the gas phase.

  5. 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.

  6. Analysis of Shear-Induced Platelet Aggregation and Breakup.

    PubMed

    Hellmuth, Rudolf; Bruzzi, Mark S; Quinlan, Nathan J

    2016-04-01

    To better understand the mechanisms leading to the formation of thrombi of hazardous sizes in the bulk of the blood, we have developed a kinetic model of shear-induced platelet aggregation (SIPA). In our model, shear rate regulates a mass-conservative population balance equation which computes the aggregation and disaggregation of platelets in a cluster mass distribution. Aggregation is modeled by the Smoluchowski coagulation equation, and disaggregation is incorporated using the aggregate breakup model of Pandya and Spielman. Previous experimental data for SIPA have been correlated with a special case of this model where only the two-body collision of free platelets was considered. However, the two-body collision theory is oblivious to the steady-state condition, and it required the use of a shear-dependent aggregation efficiency parameter to fit it to experimental data. Our method not only predicts steady states but also correlates with literature data without employing a shear-dependent aggregation efficiency. PMID:26228488

  7. 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.

  8. 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. PMID:23745615

  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. Style of rifting and the stages of Pangea breakup

    NASA Astrophysics Data System (ADS)

    Frizon de Lamotte, Dominique; Fourdan, Brendan; Leleu, Sophie; Leparmentier, François; 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction

    NASA Astrophysics Data System (ADS)

    Sargsian, Misak; Granados, Carlos

    2009-05-01

    We investigate hard photodisintegration of two nucleons from ^3He nucleus within the framework of hard rescattering model (HRM). In HRM a quark of one nucleon knocked-out by incoming photon rescatters with a quark of the other nucleon leading to the production of two nucleons with high relative momentum. HRM allows to express the amplitude of two-nucleon break-up reaction through the convolution of photon-quark scattering, NN hard scattering amplitude and nuclear spectral function which can be calculated using nonrelativistic ^3He wave function. HRM predicts several specific features for hard break-up reaction. First, the cross section will approximately scale as s-11. Also one predicts comparable or larger cross section for pp break up as compared to that of pn break-up, which is opposite to what is observed in low energy kinematics. Another result is the prediction of different spectator momentum dependencies of pp and pn break-up cross sections. This is due to the fact that same-helicity pp-component is strongly suppressed in the ground state wave function of ^3He. Due to this suppression HRM predicts significantly different asymmetries for the cross section of polarization transfer NN break-up reactions for circularly polarized photons. For the pp break-up this asymmetry is predicted to be zero while for the pn it is close to 23.

  16. Polar cap arcs: Sun-aligned or cusp-aligned?

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Paxton, L. J.; Zhang, Qinghe; Xing, Zanyang

    2016-08-01

    Polar cap arcs are often called sun-aligned arcs. Satellite observations reveal that polar cap arcs join together at the cusp and are actually cusp aligned. Strong ionospheric plasma velocity shears, thus field aligned currents, were associated with polar arcs and they were likely caused by Kelvin-Helmholtz waves around the low-latitude magnetopause under a northward IMF Bz. The magnetic field lines around the magnetopause join together in the cusp region so are the field aligned currents and particle precipitation. This explains why polar arcs are cusp aligned.

  17. Alignment and alignment transition of bent core nematics

    NASA Astrophysics Data System (ADS)

    Elamain, Omaima; Hegde, Gurumurthy; Komitov, Lachezar

    2013-07-01

    We report on the alignment of nematics consisting of bimesogen bent core molecules of chlorine substituent of benzene derivative and their binary mixture with rod like nematics. It was found that the alignment layer made from polyimide material, which is usually used for promoting vertical (homeotropic) alignment of rod like nematics, promotes instead a planar alignment of the bent core nematic and its nematic mixtures. At higher concentration of the rod like nematic component in these mixtures, a temperature driven transition from vertical to planar alignment was found near the transition to isotropic phase.

  18. 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…

  19. Contrasting Historical and Recent Breakup Styles on the Meade River of Arctic Alaska in the Context of a Warming Climate

    NASA Astrophysics Data System (ADS)

    Beck, R. A.; Hinkel, K. M.; Eisner, W. R.; Whiteman, D.; Arp, C. D.; Machida, R.; Cuomo, C.; Su, H.; Liu, H.; Kim, C.; Rettig, A.; Ivenso, C.; Yang, B.; Wu, Q.; Wang, S.; Frey, K. E.; Lenters, J. D.; Potter, B. L.

    2013-12-01

    Although data for temporal spring river ice breakup are available for a number of Arctic rivers, there is a paucity of information related to the type of breakup. The Arctic Climate Impact Assessment (ACIA) of 2005 predicted a transition from mechanical to thermal spring breakup of ice cover on arctic rivers, with this shift being greatest in exclusively Arctic watersheds where observed warming is most pronounced. We describe a rare instance of an entirely Arctic river with limited but well documented historical and recent data regarding the type of breakup. Time-series ground imagery of spring breakup from 1966, 1975, 1978, 2009, 2010 and 2012, in combination with interviews of local inhabitants, documents a shift from predominantly mechanical to predominantly thermal breakup after spring 1978 and by spring 2009 within the context of a locally and regionally warming Arctic. Recent (post-2010) and rare cloud-free visible satellite imagery shows an irregular pattern of breakup along the southern two thirds of the river. The resultant shift from predominantly mechanical to predominantly thermal breakup is predicted to result in significant changes to water, sediment, nutrient and organic carbon fluxes, as well as riparian ecology and human activities. Meade River Breakup - Spring 1966 Meade River Breakup - Spring 2010

  20. Solar Alignments - Identification and Analysis

    NASA Astrophysics Data System (ADS)

    Belmonte, Juan Antonio

    The sun was such an important divinity in antiquity, and even today, that solar alignments should be expected within a large variety of places and cultures. These are probably the most conspicuous kind of astronomical alignments a field researcher can deal with. The need for a correct identification is thus evident. The different kind of solar phenomena susceptible of being determined by astronomical alignments will be scrutinized, following by the way in which such alignments can materialize in space. It will be shown that analyzing solar alignments is not always an easy task.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. Effects of projectile resonances on the total, Coulomb, and nuclear breakup cross sections in the 6Li+152Sm reaction

    NASA Astrophysics Data System (ADS)

    Mukeru, B.; Lekala, M. L.

    2016-08-01

    In this paper we analyze the effects of the projectile resonances on the total, Coulomb, and nuclear breakup cross sections as well as on the Coulomb-nuclear interferences at different arbitrary incident energies. It is found that these resonances have non-negligible effects on the total, Coulomb, and nuclear breakup cross sections. Qualitatively, they have no effects on the constructiveness or destructiveness of the Coulomb-nuclear interferences. Quantitatively, we obtained that these resonances increase by 7.38%, 7.58%, and 20.30% the integrated total, Coulomb, and nuclear breakup cross sections, respectively at Elab=35 MeV . This shows that the nuclear breakup cross sections are more affected by the effects of the projectile resonances than their total and Coulomb breakup counterparts. We also obtain that the effects of the resonances on the total, Coulomb, and nuclear breakup cross sections decrease as the incident energy increases.

  6. Simultaneous DMSP, all-sky camera, and IMAGE FUV observations of the brightening arc at a substorm pseudo-breakup

    NASA Astrophysics Data System (ADS)

    Yago, K.; Shiokawa, K.; Yumoto, K.; Baishev, D. G.; Solovyev, S. I.; Rich, F. J.

    2007-01-01

    Auroral particles, field-aligned currents, and plasma convections in the vicinity of the brightening arc at substorm onset are still not well understood, since it is very rare to have conjugate satellite measurements above the brightening arc. In this paper, we investigate the characteristics of auroral particles and fields associated with the brightening arc at a pseudo-onset of substorm on October 31, 2000, using ground all-sky TV images, IMAGE FUV auroral images, and particle, magnetic field, and plasma flow data obtained by the DMSP F12 satellite. The arc brightening at Tixie (66.0°MLAT), Russia, occurred at 1004 UT (18.75 MLT) coincident with a coherent Pi 2 pulsation at midlatitudes and with the DMSP crossing above the arc. The brightening arc did not develop on a global scale, indicating that this event is a pseudo auroral breakup, which occurred ~16 min before the major substorm expansion onset. IMAGE auroral images indicate that the longitude of the brightening center was ~2.5 h nightside of Tixie. The DMSP data show that the precipitating particles associated with the brightening arc correspond to an electron inverted-V structure at the equatorward edge of the electron precipitation region. The arc was located in the energetic (>1 keV) ion precipitation region, near the equatorward boundary of the upward region 1 field-aligned current, and at the peak of the sunward convection velocity. These facts indicate that the brightening arc at duskside of the onset local time was located in the inner plasma sheet at the inner edge of the region 1 current source in the sunward convection region.

  7. Conditional alignment random fields for multiple motion sequence alignment.

    PubMed

    Kim, Minyoung

    2013-11-01

    We consider the multiple time-series alignment problem, typically focusing on the task of synchronizing multiple motion videos of the same kind of human activity. Finding an optimal global alignment of multiple sequences is infeasible, while there have been several approximate solutions, including iterative pairwise warping algorithms and variants of hidden Markov models. In this paper, we propose a novel probabilistic model that represents the conditional densities of the latent target sequences which are aligned with the given observed sequences through the hidden alignment variables. By imposing certain constraints on the target sequences at the learning stage, we have a sensible model for multiple alignments that can be learned very efficiently by the EM algorithm. Compared to existing methods, our approach yields more accurate alignment while being more robust to local optima and initial configurations. We demonstrate its efficacy on both synthetic and real-world motion videos including facial emotions and human activities. PMID:24051737

  8. Effects of surfactants on the deformation of microfluidic drops

    NASA Astrophysics Data System (ADS)

    Cordero, Maria Luisa; Ulloa, Camilo

    2013-11-01

    A microfluidic analog of the four-roll-mill experiment is used to study the deformation and breakup of microfluidic drops. The behavior of water drops flowing in mineral oil is quantified as a function of the capillary number, Ca , which is based on the oil viscosity, drop radius, flow shear rate and equilibrium interfacial tension, both in the presence and absence of surfactants. In the absence of surfactants the deformation of the drops increases linearly with Ca . If surfactants are added to the carrier oil then, for the same value of Ca , drops deform less if the flow velocity is larger. Moreover, for a given drop size in the presence of surfactants, drops begin to split at a threshold shear rate but stop breaking if the shear rate is increased beyond a second threshold. These observations are explained by a decrease in the surfactant concentration at the surface of the drop due to advection of surfactant molecules by the oil flow. This increases the interfacial tension, thus making the drop less deformable for higher flow velocities. We use the deformation of the drops to infer the mean interfacial tension and from this we quantify the surface concentration of surfactants at the drop interface. Work supported by FONDECYT 11100204.

  9. 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.

  10. 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.

  11. Nuclear-breakup mechanisms in the interaction of relativistic projectiles with heavy targets

    SciTech Connect

    Steinberg, E.P.

    1982-01-01

    The breakup of a Au nucleus under bombardment with relativistic p, ..cap alpha.., and /sup 20/Ne has been investigated in an extensive, multi-detector study. The present discussion addresses some of the many aspects of the experimental results. A broad distribution of coincident fragment masses is observed, with the total fragment kinetic energy being higher than expected for a fission mechanism for total fragment mass less than or equal to 120. The formation of light fragments is shown to be inconsistent with a binary breakup mechanism, and a multi-fragment target breakup is suggested. In general, the results indicate a broad spectrum of violence in the collisions, from gentle, leading to the production of heavy spallation products and fission, to essentially explosive, leading to multi-fragment breakup into light mas products. These aspects of the reactions represent a late-stage breakup of the target residues and are positively correlated with the violence of the initial fast stage of the collision as measured by the charged particle multiplicity.

  12. Three-cluster breakup in deuteron-deuteron collisions: Single-scattering approximation

    NASA Astrophysics Data System (ADS)

    Deltuva, A.; Fonseca, A. C.

    2016-04-01

    We present results for the three-cluster breakup in deuteron-deuteron collisions at 130 and 270 MeV deuteron beam energy. The breakup amplitude is calculated using the first term in the Neumann series expansion of the corresponding exact four-nucleon equations. In analogy with nucleon-deuteron breakup where an equivalent approximation is compared with exact calculations, we expect this single-scattering approximation to provide a rough estimation of three-body breakup observables in quasifree configurations. We predict the nucleon-deuteron and deuteron-deuteron three-cluster breakup cross sections to be of a comparable size and thereby question the reliability of the recent experimental data [A. Ramazani-Moghaddam-Arani, Ph.D. thesis, University of Groningen, 2009; A. Ramazani-Moghaddam-Arani et al., EPJ Web Conf. 3, 04012 (2010), 10.1051/epjconf/20100304012], which are smaller by about three orders of magnitude. We also show that an equivalent single-scattering approximation provides a reasonable description of deuteron-deuteron elastic scattering at forward-scattering angles.

  13. 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.

  14. 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.

  15. Charge separation in the aerodynamic breakup of micrometer-sized water droplets.

    PubMed

    Zilch, Lloyd W; Maze, Joshua T; Smith, John W; Ewing, George E; Jarrold, Martin F

    2008-12-25

    Charged water droplets generated by electrospray, sonic spray, and a vibrating orifice aerosol generator (VOAG) have been studied by digital macrophotography and image charge detection mass spectrometry. Image charge detection mass spectrometry provides information on the droplet size, charge, and velocity after transmission through a capillary interface. The digital images provide the droplet size distribution before they enter the capillary. Droplets with 10-100 microm radii generated by sonic spray and VOAG are reduced to 2-3 microm radii by transmission through the capillary interface. The droplets from sonic spray and VOAG are much more highly charged than expected for random charging, and positive droplets are much more prevalent than negative. For positive mode electrospray, >99% of the detected droplets carry a positive charge, whereas for negative mode electrospray, <30% of the detected droplets carry a negative charge (i.e., >70% carry a positive charge). These observation can all be accounted for by the aerodynamic breakup of the droplets in the capillary interface. This breakup reduces the droplets to a terminal size at which point further breakup does not occur. Charge separation during droplet breakup is responsible for the relatively high charges on the sonic spray and VOAG droplets and for the preference for positively charged droplets. The charge separation can be explained using the bag mechanism for droplet breakup and the electrical bilayer at the surface of water. PMID:19035820

  16. Fourier transform interferometer alignment method.

    PubMed

    Goldberg, Kenneth A; Naulleau, Patrick; Bokor, Jeffrey

    2002-08-01

    A rapid and convenient method has been developed to facilitate the alignment of the image-plane components of point-diffraction interferometers, including the phase-shifting point-diffraction interferometer. In real time, the Fourier transform of the detected image is used to calculate a pseudoimage of the electric field in the image plane of the test optic where thecritical alignment o f variousoptical components is performed. Reconstruction of the pseudoimage is similar to off-axis, Fourier transform holography. Intermediate steps in the alignment procedure are described. Fine alignment is aided by the introduction and optimization of a global-contrast parameter that is easily calculated from the Fourier transform. Additional applications include the alignment of image-plane apertures in general optical systems, the rapid identification of patterned image-plane alignment marks, and the probing of important image-plane field properties. PMID:12153074

  17. Onorbit IMU alignment error budget

    NASA Technical Reports Server (NTRS)

    Corson, R. W.

    1980-01-01

    The Star Tracker, Crew Optical Alignment Sight (COAS), and Inertial Measurement Unit (IMU) from a complex navigation system with a multitude of error sources were combined. A complete list of the system errors is presented. The errors were combined in a rational way to yield an estimate of the IMU alignment accuracy for STS-1. The expected standard deviation in the IMU alignment error for STS-1 type alignments was determined to be 72 arc seconds per axis for star tracker alignments and 188 arc seconds per axis for COAS alignments. These estimates are based on current knowledge of the star tracker, COAS, IMU, and navigation base error specifications, and were partially verified by preliminary Monte Carlo analysis.

  18. Nuclear reactor internals alignment configuration

    DOEpatents

    Gilmore, Charles B.; Singleton, Norman R.

    2009-11-10

    An alignment system that employs jacking block assemblies and alignment posts around the periphery of the top plate of a nuclear reactor lower internals core shroud to align an upper core plate with the lower internals and the core shroud with the core barrel. The distal ends of the alignment posts are chamfered and are closely received within notches machined in the upper core plate at spaced locations around the outer circumference of the upper core plate. The jacking block assemblies are used to center the core shroud in the core barrel and the alignment posts assure the proper orientation of the upper core plate. The alignment posts may alternately be formed in the upper core plate and the notches may be formed in top plate.

  19. The role of mechanical heterogeneities during continental breakup: a 3D lithospheric-scale modelling approach

    NASA Astrophysics Data System (ADS)

    Duclaux, Guillaume; Huismans, Ritske S.; May, Dave

    2015-04-01

    How and why do continents break? More than two decades of analogue and 2D plane-strain numerical experiments have shown that despite the origin of the forces driving extension, the geometry of continental rifts falls into three categories - or modes: narrow rift, wide rift, or core complex. The mode of extension itself is strongly influenced by the rheology (and rheological behaviour) of the modelled layered system. In every model, an initial thermal or mechanical heterogeneity, such as a weak seed or a notch, is imposed to help localise the deformation and avoid uniform stretching of the lithosphere by pure shear. While it is widely accepted that structural inheritance is a key parameter for controlling rift localisation - as implied by the Wilson Cycle - modelling the effect of lithospheric heterogeneities on the long-term tectonic evolution of an extending plate in full 3D remains challenging. Recent progress in finite-element methods applied to computational tectonics along with the improved accessibility to high performance computers, now enable to switch from plane strain thermo-mechanical experiments to full 3D high-resolution experiments. Here we investigate the role of mechanical heterogeneities on rift opening, linkage and propagation during extension of a layered lithospheric systems with pTatin3d, a geodynamics modeling package utilising the material-point-method for tracking material composition, combined with a multigrid finite-element method to solve heterogeneous, incompressible visco-plastic Stokes problems. The initial model setup consists in a box of 1200 km horizontally by 250 km deep. It includes a 35 km layer of continental crust, underlaid by 85 km of sub-continental lithospheric mantle, and an asthenospheric mantle. Crust and mantle have visco-plastic rheologies with a pressure dependent yielding, which includes strain weakening, and a temperature, stress, strain-rate-dependent viscosity based on wet quartzite rheology for the crust, and wet

  20. 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

  1. 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.; 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 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

  2. 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.; 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 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

  3. 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

  4. The Porcupine Basin: from rifting to continental breakup

    NASA Astrophysics Data System (ADS)

    Reston, Timothy; Gaw, Viola; Klaeschen, Dirk; McDermott, Ken

    2015-04-01

    Southwest of Ireland, the Porcupine Basin is characterized by axial stretching factors that increase southward to values greater than six and typical of rifted margins. As such, the basin can be regarded as a natural laboratory to investigate the evolution and symmetry of rifting leading towards continental separation and breakup, and in particular the processes of mantle serpentinisation, and the onset of detachment faulting. We have processed through to prestack depth migration a series of E-W profiles crossing the basin at different axial stretching factors and linked by a N-S profile running close to the rift axis. Our results constrain the structure of the basin and have implications for the evolution of rifted margins. In the north at a latitude of 52.25N, no clear detachment is imaged, although faults do appear to cut down into the mantle, so that serpentinisation may have started. Further south (51.75N), a bright reflection (here named P) cuts down to the west from the base of the sedimentary section, is overlain by small fault blocks and appears to represent a detachment fault. P may in part follow the top of partially serpentinized mantle: this interpretation is consistent with gravity modelling, with numerical models of crustal embrittlement and mantle serpentinization during extension and with wide-angle data (see posters of Prada and of Watremez). Furthermore, P closely resembles the S reflection west of Iberia, where such serpentinites are well documented. P develops where the crust was thinned to less than 3 km during rifting, again similar to S. Although overall the basin remains symmetrical, the consistent westward structural dip of the detachment implies that, at high stretching factors, extension became asymmetric. Analysis of the depth sections suggests that the detachment may have been active as a rolling hinge rooting at low-angle beneath the Porcupine Bank, consistent with the presence of a footwall of serpentinites. This requires very weak

  5. Effects of thermal quenching on the breakup of pyroclasts

    NASA Astrophysics Data System (ADS)

    Patel, A.; Manga, M.; Carey, R. J.; Degruyter, W.; Dufek, J.

    2012-12-01

    wet density increased 0 to 2.5 %, as measured after 5 minutes immersion in water. Overall we see modest differences between quenched pumice and regular pumice in breakup, abrasion, mass, and effective wet density. Experimental results suggest that quenching may damage small parts of a clast but tends not to cause cracks that propagate easily through the clast. XRT and SEM imaging confirms that quenching only damages small external parts. This is in stark contrast to non-vesicular glass that develops large cracks on quenching.

  6. Aligned Defrosting Dunes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    17 August 2004 This July 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of aligned barchan sand dunes in the martian north polar region. At the time, the dunes were covered with seasonal frost, but the frost had begun to sublime away, leaving dark spots and dark outlines around the dunes. The surrounding plains exhibit small, diffuse spots that are also the result of subliming seasonal frost. This northern spring image, acquired on a descending ground track (as MGS was moving north to south on the 'night' side of Mars) is located near 78.8oN, 34.8oW. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.

  7. Alignment system for encoders

    NASA Technical Reports Server (NTRS)

    Villani, Daniel D. (Inventor)

    1988-01-01

    An improved encoder alignment system is disclosed which provides an indication of the extent of misalignment and a measure of the rate at which the misalignment may be changing. The invention is adapted for use with a conventional encoder which provides a digital coarse word having at least significant bit and a digital fine word having a least significant bit and a most significant bit. The invention generates the exclusive or of the least significant bit of the coarse digital signal and the least significant bit of the fine digital signal to provide a first signal. The invention then generates the exclusive or of the first signal and the complement of the most significant bit of the fine digital signal to provide an output signal which represents the misalignment of the encoder.

  8. Lunar Alignments - Identification and Analysis

    NASA Astrophysics Data System (ADS)

    González-García, A. César

    Lunar alignments are difficult to establish given the apparent lack of written accounts clearly pointing toward lunar alignments for individual temples. While some individual cases are reviewed and highlighted, the weight of the proof must fall on statistical sampling. Some definitions for the lunar alignments are provided in order to clarify the targets, and thus, some new tools are provided to try to test the lunar hypothesis in several cases, especially in megalithic astronomy.

  9. 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.

  10. Gold Alignment and Internal Dissipation

    NASA Astrophysics Data System (ADS)

    Lazarian, A.

    1997-07-01

    The measures of mechanical alignment are obtained for both prolate and oblate grains whose temperatures are comparable to the grain kinetic energy divided by k, the Boltzmann constant. For such grains, the alignment of angular momentum, J, with the axis of maximal inertia, a, is only partial, which substantially alters the mechanical alignment as compared with the results obtained by Lazarian and Roberge, Hanany, & Messinger under the assumption of perfect alignment. We also describe Gold alignment when the Barnett dissipation is suppressed and derive an analytical expression that relates the measure of alignment to the parameters of grain nonsphericity and the direction of the gas-grain drift. This solution provides the lower limit for the measure of alignment, while the upper limit is given by the method derived by Lazarian. Using the results of a recent study of incomplete internal relaxation by Lazarian & Roberge, we find measures of alignment for the whole range of ratios of grain rotational energy to kTs, where Ts is the grain temperature. To describe alignment for mildly supersonic drifts, we suggest an analytical approach that provides good correspondence with the results of direct numerical simulations by Roberge, Hanany, & Messinger. We also extend our approach to account for simultaneous action of the Gold and Davis-Greenstein mechanisms.

  11. 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.

  12. 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.

  13. Ice breakup forecast in the reach of the Yellow River: the support vector machines approach

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Li, W.; Zhang, C.; Liu, J.

    2009-04-01

    Accurate lead-time forecast of ice breakup is one of the key aspects for ice flood prevention and reducing losses. In this paper, a new data-driven model based on the Statistical Learning Theory was employed for ice breakup prediction. The model, known as Support Vector Machine (SVM), follows the principle that aims at minimizing the structural risk rather than the empirical risk. In order to estimate the appropriate parameters of the SVM, Multiobjective Shuffled Complex Evolution Metropolis (MOSCEM-UA) algorithm is performed through exponential transformation. A case study was conducted in the reach of the Yellow River. Results from the proposed model showed a promising performance compared with that from artificial neural network, so the model can be considered as an alternative and practical tool for ice breakup forecast.

  14. 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.

  15. Instability of Nano- and Microscale Liquid Metal Filaments: Transition from Single Droplet Collapse to Multidroplet Breakup.

    PubMed

    Hartnett, C A; Mahady, K; Fowlkes, J D; Afkhami, S; Kondic, L; Rack, P D

    2015-12-22

    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. In addition, 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. PMID:26595519

  16. Energy dependence of breakup cross sections of the halo nucleus {sup 8}B and effective interactions

    SciTech Connect

    Bertulani, C.A.; Lotti, P.; Sagawa, H.

    1998-01-01

    We study the energy dependence of the cross sections for nucleon removal of {sup 8}B projectiles. It is shown that the Glauber model calculations with nucleon-nucleon t-matrix reproduce well the energy dependence of the breakup cross sections of {sup 8}B. A distorted wave Born approximation (DWBA) model for the breakup cross section is also proposed and results are compared with those of the Glauber model. We show that to obtain an agreement between the DWBA calculations, the Glauber formalism, and the experimental data, it is necessary to modify the energy behavior of the effective interaction. In particular, the breakup potential has a quite different energy dependence than the strong absorption potential. {copyright} {ital 1998} {ital The American Physical Society}

  17. Study of the beam breakup mode in linear induction accelerators for heavy ions

    SciTech Connect

    Chattopadhyay, S.; Faltens, A.; Smith, L.

    1981-03-01

    A simple theoretical study and numerical estimate is presented for the transverse amplitude growth of a nonrelativistic heavy ion beam in an induction linac, as envisaged for use in commercial power plants, due to the nonregenerative coherent beam breakup mode. An equivalent electrical circuit has been used to represent the accelerating induction modules. Our calculation shows that for the parameters of interest, the beam breakup amplitude for a heavy ion beam grows extremely slowly in the time scales of interest, to magnitudes insignificant for transport purposes. It is concluded that the coherent beam breakup mode does not pose any serious threat to the stability of a high current (kA) heavy ion beam in an induction linac.

  18. Determining astrophysical three-body radiative capture reaction rates from inclusive Coulomb break-up measurements

    NASA Astrophysics Data System (ADS)

    Casal, J.; Rodríguez-Gallardo, M.; Arias, J. M.; Gómez-Camacho, J.

    2016-04-01

    A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of B (E 1 ) distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to 11Li (9Li+n +n ) and 6He (4He+n +n ) three-body systems for which some data exist.

  19. Imaging and photometry of comet C/1999 S4 (LINEAR) before perihelion and after breakup.

    PubMed

    Farnham, T L; Schleicher, D G; Woodney, L M; Birch, P V; Eberhardy, C A; Levy, L

    2001-05-18

    We analyzed photometric measurements and images of comet C/LINEAR before perihelion and after its breakup. Results from our photometry data include a lower limit of 0.44 kilometer for the radius of the nucleus before breakup, and a determination that it was depleted in carbon-chain molecules relative to most other comets. Our imaging and modeling results, which include a constraint on the rotational state of the nucleus, indicate that the disintegration likely started on 18 or 19 July 2000. The total mass detectable in the dust tail after the breakup was 3 x 10(8) kilograms, comparable to one of the fragments in the Hubble Space Telescope images; we therefore infer that most of the comet's original mass is hidden in remnants between 1 millimeter and 50 meters in diameter. PMID:11359005

  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. Research on the Rebound and Breakup of the Droplet after Impacting on the Superhydrophobic Wall

    NASA Astrophysics Data System (ADS)

    Liu, D. W.; Ning, Z.; Lü, M.; Yan, K.; Sun, C. H.

    The surface hydrophilicity affects the movement of the droplet intensively when the droplet impacting on a wall, In this paper, the motion of the droplet after impacting on the superhydrophobic wall were researched by using the combined Level Set-VOF method for gas-liquid interface tracking. The results show that, the droplet would rebound after impacting on the superhydrophobic wall when the velocity is small: the droplet would breakup after when the velocity is larger; the droplet would breakup during spreading when the initial diameter is larger and less surface tension: impact angle affect the movement of the chop-let intensively after impacting on the wall. At the same time, this paper obtains critical conditions of rebound an breakup after droplet impacts on the superliydrophbic wall by vertical or inclined angle through numerical simulation in a certain range of condition.

  2. Alignment Analyses in the Varus Osteoarthritic Knee Using Computer Navigation.

    PubMed

    Tan, Kelvin G; Sathappan, Sathappan S; Teo, Yee Hong; Low, Wilson C J

    2015-06-01

    Osteoarthritic (OA) knees with severe extension varus deformity seem to have correspondingly more severe flexion varus, especially beyond a certain tibiofemoral angle. Clinical measurement of flexion varus and fixed flexion deformity (FFD), which had been difficult to perform because of the spatial alignment of the knee in flexion, was recently made possible with computer navigation. We conducted a study to evaluate the relationship of extension and flexion varus in OA knees and to determine whether severity of FFD in the sagittal plane correlates with severity of coronal plane varus deformity. The study included 317 consecutive cases of computer-navigated total knee arthroplasty performed on OA knees with varus deformities. Three sets of values were extracted from the navigation data: varus angle at maximal knee extension, 90° knee flexion, and maximal knee extension. Correlation analyses were performed for extension and flexion varus, FFD, and coronal plane deformity. OA knees with extension varus of more than 10° had an incremental likelihood of more severe flexion varus. When the extension varus angle exceeded 20°, probability became almost certainty. There was no correlation between FFD and coronal plane varus deformity. PMID:26046998

  3. 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

  4. 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.

  5. Deformable Nanolaminate Optics

    SciTech Connect

    Olivier, S S; Papavasiliou, A P; Barbee, T W; Miles, R R; Walton, C C; Cohn, M B; Chang, K

    2006-05-12

    We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.

  6. Cumulative Beam Breakup in Linear Accelerators with Arbitrary Beam Current Profile

    SciTech Connect

    Jean Delayen

    2003-06-01

    An analytical formalism for the solution of cumulative beam breakup in linear accelerators with arbitrary time dependence of beam current is presented, and a closed-form expression for the time and position dependence of the transverse displacement is obtained. It is applied to the behavior of single bunches and to the steady state and transient behavior of dc beams and beams composed of point-like and finite length bunches. This formalism is also applied to the problem of cumulative beam breakup in the presence of random displacement of cavities and focusing elements, and a general solution is presented.

  7. Alpha-particle scattering from sup 6 Li near the. alpha. - d breakup threshold

    SciTech Connect

    Samanta, C.; Ghosh, S.; Lahiri, M. ); Ray, S. ); Banerjee, S.R. )

    1992-04-01

    The {sup 6}Li({alpha},{alpha}{prime}) reaction was studied at {ital E}{sub {alpha}}=50 MeV. The angular distribution of the continuum region near the {sup 6}Li{r arrow}{alpha}+{ital d} breakup threshold (1.475 MeV) was measured for {theta}{sub lab}=7{degree}--40{degree}. The data were analyzed in terms of plane-wave and distorted-wave impulse approximation calculations. To study the possible effects of recombination of the breakup clusters in the exit channel, distorted-wave Born approximation calculations were also performed.

  8. Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Datta Pramanik, U.; Aumann, T.; Beceiro, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chatterjee, S.; Chartier, M.; Cortina-Gil, D.; De Angelis, G.; Gonzalez-Diaz, D.; Emling, H.; Diaz Fernandez, P.; Fraile, L. M.; Ershova, O.; Geissel, H.; Heil, M.; Jonson, B.; Kelic, A.; Johansson, H.; Kruecken, R.; Kroll, T.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Munzenberg, G.; Marganiec, J.; Nociforo, C.; Najafi, A.; Panin, V.; Paschalis, S.; Pietri, S.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Ray, J.; Simon, H.; Scheidenberger, C.; Typel, S.; Taylor, J.; Togano, Y.; Volkov, V.; Weick, H.; Wagner, A.; Wamers, F.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2014-03-01

    Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s)⊗νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al.

  9. 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.

  10. Configuration space Faddeev equations within the general formalism for studying Nd breakup scattering

    NASA Astrophysics Data System (ADS)

    Suslov, Vladimir; Braun, Mikhail; Filikhin, Igor; Vlahovic, Branislav; Slaus, Ivo

    2015-10-01

    Appropriate modifications of the configuration space Faddeev equations have been made to study the three-nucleon system assuming the neutrons and protons to be distinguishable. Breakup amplitudes for n-d and p-d scattering at Elab =14.1 MeV are calculated in s-wave approach with the Malfliet-Tjon MT I-III and AV14 potentials. Results obtained for Nd breakup scattering in quartet and doublet spin states are compared with our predictions and those of the Los-Alamos/Iowa group. This work is supported by NSF CREST (HRD-0833184).

  11. Calculation of proton-deuteron breakup reactions including the Coulomb interaction between the two protons.

    PubMed

    Deltuva, A; Fonseca, A C; Sauer, P U

    2005-08-26

    The Coulomb interaction between the two protons is fully included in the calculation of proton-deuteron breakup with realistic interactions for the first time. The hadron dynamics is based on the purely nucleonic charge-dependent (CD) Bonn potential and its realistic extension CD Bonn +Delta to a coupled-channel two-baryon potential, allowing for single virtual Delta-isobar excitation. Calculations are done using integral equations in momentum space. The screening and renormalization approach is employed for including the Coulomb interaction. The Coulomb effect on breakup observables is seen at all energies in particular kinematic regimes. PMID:16197210

  12. Calculation of multichannel reactions in the four-nucleon system above breakup threshold.

    PubMed

    Deltuva, A; Fonseca, A C

    2014-09-01

    The exact four-body equations of Alt, Grassberger, and Sandhas are solved for neutron-3He and proton-3H scattering in the energy regime above the four-nucleon breakup threshold. Cross sections and spin observables for elastic, transfer, charge-exchange, and breakup reactions are calculated using realistic nucleon-nucleon interaction models, including the one with effective many-nucleon forces due to explicit Δ-isobar excitation. The experimental data are described reasonably well with only few exceptions such as vector analyzing powers. PMID:25238352

  13. 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.

  14. 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.

  15. Analysis of a combined tip-tilt and deformable mirror.

    PubMed

    Wilcox, Christopher C; Andrews, Jonathan R; Restaino, Sergio R; Teare, Scott W; Payne, Don M; Krishna, Sanjay

    2006-03-15

    A deformable mirror mounted on a two-axis tilt platform can provide wavefront compensation at a single location in an adaptive optics system, resulting in a significant reduction in the number of optical components in the system and in a simplification of the alignment. However, the moment of inertia of a deformable mirror is significantly different from that of the monolithic mirror commonly mounted on a tilt platform. We report on what are to our knowledge the first experimental results of mounting a microelectromechanical deformable mirror onto a fast steering platform and the first observation that at low operating frequencies high-order deformation of the deformable mirror membrane was not recorded. PMID:16544588

  16. Drive alignment pays maintenance dividends

    SciTech Connect

    Fedder, R.

    2008-12-15

    Proper alignment of the motor and gear drive on conveying and processing equipment will result in longer bearing and coupling life, along with lower maintenance costs. Selecting an alignment free drive package instead of a traditional foot mounted drive and motor is a major advancement toward these goals. 4 photos.

  17. Lexical alignment in triadic communication

    PubMed Central

    Foltz, Anouschka; Gaspers, Judith; Thiele, Kristina; Stenneken, Prisca; Cimiano, Philipp

    2015-01-01

    Lexical alignment refers to the adoption of one’s interlocutor’s lexical items. Accounts of the mechanisms underlying such lexical alignment differ (among other aspects) in the role assigned to addressee-centered behavior. In this study, we used a triadic communicative situation to test which factors may modulate the extent to which participants’ lexical alignment reflects addressee-centered behavior. Pairs of naïve participants played a picture matching game and received information about the order in which pictures were to be matched from a voice over headphones. On critical trials, participants did or did not hear a name for the picture to be matched next over headphones. Importantly, when the voice over headphones provided a name, it did not match the name that the interlocutor had previously used to describe the object. Participants overwhelmingly used the word that the voice over headphones provided. This result points to non-addressee-centered behavior and is discussed in terms of disrupting alignment with the interlocutor as well as in terms of establishing alignment with the voice over headphones. In addition, the type of picture (line drawing vs. tangram shape) independently modulated lexical alignment, such that participants showed more lexical alignment to their interlocutor for (more ambiguous) tangram shapes compared to line drawings. Overall, the results point to a rather large role for non-addressee-centered behavior during lexical alignment. PMID:25762955

  18. Semiautomated improvement of RNA alignments

    PubMed Central

    Andersen, Ebbe S.; Lind-Thomsen, Allan; Knudsen, Bjarne; Kristensen, Susie E.; Havgaard, Jakob H.; Torarinsson, Elfar; Larsen, Niels; Zwieb, Christian; Sestoft, Peter; Kjems, Jørgen; Gorodkin, Jan

    2007-01-01

    We have developed a semiautomated RNA sequence editor (SARSE) that integrates tools for analyzing RNA alignments. The editor highlights different properties of the alignment by color, and its integrated analysis tools prevent the introduction of errors when doing alignment editing. SARSE readily connects to external tools to provide a flexible semiautomatic editing environment. A new method, Pcluster, is introduced for dividing the sequences of an RNA alignment into subgroups with secondary structure differences. Pcluster was used to evaluate 574 seed alignments obtained from the Rfam database and we identified 71 alignments with significant prediction of inconsistent base pairs and 102 alignments with significant prediction of novel base pairs. Four RNA families were used to illustrate how SARSE can be used to manually or automatically correct the inconsistent base pairs detected by Pcluster: the mir-399 RNA, vertebrate telomase RNA (vert-TR), bacterial transfer-messenger RNA (tmRNA), and the signal recognition particle (SRP) RNA. The general use of the method is illustrated by the ability to accommodate pseudoknots and handle even large and divergent RNA families. The open architecture of the SARSE editor makes it a flexible tool to improve all RNA alignments with relatively little human intervention. Online documentation and software are available at http://sarse.ku.dk. PMID:17804647

  19. Well-pump alignment system

    DOEpatents

    Drumheller, Douglas S.

    1998-01-01

    An improved well-pump for geothermal wells, an alignment system for a well-pump, and to a method for aligning a rotor and stator within a well-pump, wherein the well-pump has a whistle assembly formed at a bottom portion thereof, such that variations in the frequency of the whistle, indicating misalignment, may be monitored during pumping.

  20. On the alignment of quasars

    NASA Astrophysics Data System (ADS)

    Zhu, X.-F.

    1986-06-01

    Taking the two Savage-Bolton 5 deg x 5 deg regions of optical quasar patrol as samples, a systematic analysis of the number of aligned quasars was made and compared with the random data generated by Monte Carlo method. The statistical result is that, at least for these two samples, there is no clear evidence for alignment.

  1. On the alignment of quasars

    NASA Astrophysics Data System (ADS)

    Zhu, Xing-fen

    1986-06-01

    Taking the two Savage-Bolton 5° × 5° regions of optical quasar patrol as samples, I made a systematic analysis of the number of aligned quasars and compared with the random data generated by Monte Carlo method. The statistical result is that, at least for these two samples, there is no clear evidence for alignment.

  2. CATO: The Clone Alignment Tool.

    PubMed

    Henstock, Peter V; LaPan, Peter

    2016-01-01

    High-throughput cloning efforts produce large numbers of sequences that need to be aligned, edited, compared with reference sequences, and organized as files and selected clones. Different pieces of software are typically required to perform each of these tasks. We have designed a single piece of software, CATO, the Clone Alignment Tool, that allows a user to align, evaluate, edit, and select clone sequences based on comparisons to reference sequences. The input and output are designed to be compatible with standard data formats, and thus suitable for integration into a clone processing pipeline. CATO provides both sequence alignment and visualizations to facilitate the analysis of cloning experiments. The alignment algorithm matches each of the relevant candidate sequences against each reference sequence. The visualization portion displays three levels of matching: 1) a top-level summary of the top candidate sequences aligned to each reference sequence, 2) a focused alignment view with the nucleotides of matched sequences displayed against one reference sequence, and 3) a pair-wise alignment of a single reference and candidate sequence pair. Users can select the minimum matching criteria for valid clones, edit or swap reference sequences, and export the results to a summary file as part of the high-throughput cloning workflow. PMID:27459605

  3. CATO: The Clone Alignment Tool

    PubMed Central

    Henstock, Peter V.; LaPan, Peter

    2016-01-01

    High-throughput cloning efforts produce large numbers of sequences that need to be aligned, edited, compared with reference sequences, and organized as files and selected clones. Different pieces of software are typically required to perform each of these tasks. We have designed a single piece of software, CATO, the Clone Alignment Tool, that allows a user to align, evaluate, edit, and select clone sequences based on comparisons to reference sequences. The input and output are designed to be compatible with standard data formats, and thus suitable for integration into a clone processing pipeline. CATO provides both sequence alignment and visualizations to facilitate the analysis of cloning experiments. The alignment algorithm matches each of the relevant candidate sequences against each reference sequence. The visualization portion displays three levels of matching: 1) a top-level summary of the top candidate sequences aligned to each reference sequence, 2) a focused alignment view with the nucleotides of matched sequences displayed against one reference sequence, and 3) a pair-wise alignment of a single reference and candidate sequence pair. Users can select the minimum matching criteria for valid clones, edit or swap reference sequences, and export the results to a summary file as part of the high-throughput cloning workflow. PMID:27459605

  4. Does deformation saturate seismic anisotropy?

    NASA Astrophysics Data System (ADS)

    Tatham, D. J.; Lloyd, G. E.; Butler, R. W.; Casey, M.

    2006-12-01

    The progressive simple shear deformation that characterizes ductile fault zones in the crust involves both rotation and intensification of the strain ellipsoid. These mathematic predictions have been confirmed repeatedly by finite strain determinations in outcrop studies of natural shear zones and used to test geodynamic models of mountain belts. Seismic anisotropy (SA) methods offer the opportunity to pursue these approaches in situ. First however, we must calibrate the magnitude and orientation of the SA ellipsoid against naturally deformed tectonites of known strain state and microstructure. Here we present data from a field analogue of mafic ductile crust in an amphibolite-facies shear zone developed in a deformed mafic dyke embedded within the Lewisian Gneiss (Badcall, NW Scotland). Deflection of pre-existing linear and planar elements and attenuation of the dyke into the shear zone are used to determine the strain gradient. Specimens collected along this gradient were used to establish the geometric fabric intensity defined by different minerals (hornblende grain alignment and ellipticity of plagioclase clots). Finally, petrophysical properties were calculated for the specimens using the SEM-EBSD measured populations of lattice preferred orientations (LPO) for all mineral phases. It is the hornblende-plagioclase LPO, combined in their modal proportions and modulated by the individual mineral single crystal elastic properties, which define the SA profile across the shear zone. Hornblende develops a strong preferred dimensional orientation and hence LPO at shear strains of about 2, whereas the plagioclase LPO remains close to random regardless of bulk strain. The modelled SA of the samples is dominated therefore by the amphibole LPO. Although the values of bulk shear strain vary across the shear zone (0 at the margins to greater than 12 in the centre), the calculated intensity of SA saturates at a shear strain of about 2. These results, if typical of large

  5. 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.

  6. Space Mirror Alignment System

    NASA Technical Reports Server (NTRS)

    Jau, Bruno M.; McKinney, Colin; Smythe, Robert F.; Palmer, Dean L.

    2011-01-01

    An optical alignment mirror mechanism (AMM) has been developed with angular positioning accuracy of +/-0.2 arcsec. This requires the mirror s linear positioning actuators to have positioning resolutions of +/-112 nm to enable the mirror to meet the angular tip/tilt accuracy requirement. Demonstrated capabilities are 0.1 arc-sec angular mirror positioning accuracy, which translates into linear positioning resolutions at the actuator of 50 nm. The mechanism consists of a structure with sets of cross-directional flexures that enable the mirror s tip and tilt motion, a mirror with its kinematic mount, and two linear actuators. An actuator comprises a brushless DC motor, a linear ball screw, and a piezoelectric brake that holds the mirror s position while the unit is unpowered. An interferometric linear position sensor senses the actuator s position. The AMMs were developed for an Astrometric Beam Combiner (ABC) optical bench, which is part of an interferometer development. Custom electronics were also developed to accommodate the presence of multiple AMMs within the ABC and provide a compact, all-in-one solution to power and control the AMMs.

  7. Alignment positioning mechanism

    NASA Technical Reports Server (NTRS)

    Fantasia, Peter M. (Inventor)

    1991-01-01

    An alignment positioning mechanism for correcting and compensating for misalignment of structures to be coupled is disclosed. The mechanism comprises a power screw with a base portion and a threaded shank portion. A mounting fixture is provided for rigidly coupling said base portion to the mounting interface of a supporting structure with the axis of the screw perpendicular thereto. A traveling ball nut threaded on the power screw is formed with an external annular arcuate surface configured in the form of a spherical segment and enclosed by a ball nut housing with a conforming arcuate surface for permitting gimballed motion thereon. The ball nut housing is provided with a mounting surface which is positionable in cooperable engagement with the mounting interface of a primary structure to be coupled to the supporting structure. Cooperative means are provided on the ball nut and ball nut housing, respectively, for positioning the ball nut and ball nut housing in relative gimballed position within a predetermined range of relative angular relationship whereby severe structural stresses due to unequal loadings and undesirable bending moments on the mechanism are avoided.

  8. Alignment-Annotator web server: rendering and annotating sequence alignments

    PubMed Central

    Gille, Christoph; Fähling, Michael; Weyand, Birgit; Wieland, Thomas; Gille, Andreas

    2014-01-01

    Alignment-Annotator is a novel web service designed to generate interactive views of annotated nucleotide and amino acid sequence alignments (i) de novo and (ii) embedded in other software. All computations are performed at server side. Interactivity is implemented in HTML5, a language native to web browsers. The alignment is initially displayed using default settings and can be modified with the graphical user interfaces. For example, individual sequences can be reordered or deleted using drag and drop, amino acid color code schemes can be applied and annotations can be added. Annotations can be made manually or imported (BioDAS servers, the UniProt, the Catalytic Site Atlas and the PDB). Some edits take immediate effect while others require server interaction and may take a few seconds to execute. The final alignment document can be downloaded as a zip-archive containing the HTML files. Because of the use of HTML the resulting interactive alignment can be viewed on any platform including Windows, Mac OS X, Linux, Android and iOS in any standard web browser. Importantly, no plugins nor Java are required and therefore Alignment-Anotator represents the first interactive browser-based alignment visualization. Availability: http://www.bioinformatics.org/strap/aa/ and http://strap.charite.de/aa/. PMID:24813445

  9. Experimental analysis of shape deformation of evaporating droplet using Legendre polynomials

    NASA Astrophysics Data System (ADS)

    Sanyal, Apratim; Basu, Saptarshi; Kumar, Ranganathan

    2014-01-01

    Experiments involving heating of liquid droplets which are acoustically levitated, reveal specific modes of oscillations. For a given radiation flux, certain fluid droplets undergo distortion leading to catastrophic bag type breakup. The voltage of the acoustic levitator has been kept constant to operate at a nominal acoustic pressure intensity, throughout the experiments. Thus the droplet shape instabilities are primarily a consequence of droplet heating through vapor pressure, surface tension and viscosity. A novel approach is used by employing Legendre polynomials for the mode shape approximation to describe the thermally induced instabilities. The two dominant Legendre modes essentially reflect (a) the droplet size reduction due to evaporation, and (b) the deformation around the equilibrium shape. Dissipation and inter-coupling of modal energy lead to stable droplet shape while accumulation of the same ultimately results in droplet breakup.

  10. Microstructural changes, steady-state deformation and strain localisation during large strain deformation of rocks

    NASA Astrophysics Data System (ADS)

    Barnhoorn, A.

    2012-04-01

    Ductile deformation in the Earth's crust and mantle is often concentrated in narrow shear zones. These shear zones play a fundamental role in the deformation dynamics of the earth's lithosphere during mountain building, subduction and continental break-up. Shear zones exhibit large amounts of strain with an increase in strain from the edge to the center of the shear zone. Those large strains are often accompanied with large changes in microstructure due to processes such as dynamic recrystallization, grain size refinement, development of strong foliations, development of crystallographic preferred orientations, weakening of the rock as well as progressive localisation of the deformation into more and more concentrated zones. The interplay between all those different processes produce the various microstructures that are often studied in natural shear zones to assess the deformation conditions and history of plate tectonic processes. Experimental deformation studies under controlled conditions are used to produce relationships between the different processes active in shear zones (rheology, microstructural changes, and CPO development) in order to make those quantitative inferences on natural shear zones, Here I will present the outcomes from large strain torsion experiments at elevated temperatures and pressures on monophase calcitic rocks showing that very large strains are needed before true steady-state conditions in rocks are attained. Continuous changes in crystallographic preferred orientations and continuous dynamic recrystallization by grain boundary migration and subgrain rotation recrystallization occur up to the largest shear strains achieved in the study (shear strain of 50). Dynamic recrystallization from an undeformed coarse-grained calcite rock types towards a fine-grained ultramylonite is accompanied by a modest (~20%) weakening of the rock. However, this modest weakening never caused strain localisation in the samples. In contrast to the

  11. Testing the tidal alignment model of galaxy intrinsic alignment

    SciTech Connect

    Blazek, Jonathan; Seljak, Uroš; McQuinn, Matthew E-mail: mmcquinn@berkeley.edu

    2011-05-01

    Weak gravitational lensing has become a powerful probe of large-scale structure and cosmological parameters. Precision weak lensing measurements require an understanding of the intrinsic alignment of galaxy ellipticities, which can in turn inform models of galaxy formation. It is hypothesized that elliptical galaxies align with the background tidal field and that this alignment mechanism dominates the correlation between ellipticities on cosmological scales (in the absence of lensing). We use recent large-scale structure measurements from the Sloan Digital Sky Survey to test this picture with several statistics: (1) the correlation between ellipticity and galaxy overdensity, w{sub g+}; (2) the intrinsic alignment auto-correlation functions; (3) the correlation functions of curl-free, E, and divergence-free, B, modes, the latter of which is zero in the linear tidal alignment theory; (4) the alignment correlation function, w{sub g}(r{sub p},θ), a recently developed statistic that generalizes the galaxy correlation function to account for the angle between the galaxy separation vector and the principle axis of ellipticity. We show that recent measurements are largely consistent with the tidal alignment model and discuss dependence on galaxy luminosity. In addition, we show that at linear order the tidal alignment model predicts that the angular dependence of w{sub g}(r{sub p},θ) is simply w{sub g+}(r{sub p})cos (2θ) and that this dependence is consistent with recent measurements. We also study how stochastic nonlinear contributions to galaxy ellipticity impact these statistics. We find that a significant fraction of the observed LRG ellipticity can be explained by alignment with the tidal field on scales ∼> 10 \\hMpc. These considerations are relevant to galaxy formation and evolution.

  12. Advanced Mask Aligner Lithography (AMALITH)

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Vogler, Uwe; Bramati, Arianna

    2015-03-01

    Mask aligner lithography is very attractive for less-critical lithography layers and is widely used for LED, display, CMOS image sensor, micro-fluidics and MEMS manufacturing. Mask aligner lithography is also a preferred choice the semiconductor back-end for 3D-IC, TSV interconnects, advanced packaging (AdP) and wafer-level-packaging (WLP). Mask aligner lithography is a mature technique based on shadow printing and has not much changed since the 1980s. In shadow printing lithography a geometric pattern is transferred by free-space propagation from a photomask to a photosensitive layer on a wafer. The inherent simplicity of the pattern transfer offers ease of operation, low maintenance, moderate capital expenditure, high wafers-per-hour (WPH) throughput, and attractive cost-of-ownership (COO). Advanced mask aligner lithography (AMALITH) comprises different measures to improve shadow printing lithography beyond current limits. The key enabling technology for AMALITH is a novel light integrator systems, referred to as MO Exposure Optics® (MOEO). MOEO allows to fully control and shape the properties of the illumination light in a mask aligner. Full control is the base for accurate simulation and optimization of the shadow printing process (computational lithography). Now photolithography enhancement techniques like customized illumination, optical proximity correction (OPC), phase masks (AAPSM), half-tone lithography and Talbot lithography could be used in mask aligner lithography. We summarize the recent progress in advanced mask aligner lithography (AMALITH) and discuss possible measures to further improve shadow printing lithography.

  13. Characterization of the 2012-044C Briz-M Upper Stage Breakup

    NASA Technical Reports Server (NTRS)

    Matney, M. J.; Hamilton, J.; Horstman, M.; Papanyan, V.

    2013-01-01

    On 6 August, 2012, Russia launched two commercial satellites aboard a Proton rocket, and attempted to place them in geosynchronous orbit using a Briz-M upper stage (2012-044C, SSN 38746). Unfortunately, the upper stage failed early in its burn and was left stranded in an elliptical orbit with a perigee in low Earth orbit (LEO). Because the stage failed with much of its fuel on board, it was deemed a significant breakup risk. These fears were confirmed when it broke up 16 October, creating a large cloud of debris with perigees below that of the International Space Station. The debris cloud was tracked by the US Space Surveillance Network (SSN), which can reliably detect and track objects down to about 10 cm in size. Because of the unusual geometry of the breakup, there was an opportunity for NASA Orbital Debris Program Office to use specialized radar assets to characterize the extent of the debris cloud in sizes smaller than the standard debris tracked by the SSN. This paper will describe the observation campaign to measure the small particle distributions of this cloud, and presents the results of the analysis of the data. We shall compare the data to the modelled size distribution, number, and shape of the cloud, and what implications this may have for future breakup debris models. We shall conclude the paper with a discussion how this measurement process can be improved for future breakups.

  14. Effect of interior surface finish on the break-up of commercial shaped charge liners

    SciTech Connect

    Baker, E L; Schwartz, A J

    1999-08-11

    A series of experiments aimed at understanding the influence of the liner interior surface finish on the break-up of shaped charge jets has been completed. The experiments used a standard 81-mm shaped charge design, loaded with LX-14 high explosive; incorporating high-precision copper shaped charged liners. The results indicate that a significant reduction of jet break-up time occurs between a surface finish of 99.30 microinches and 375.65 microinches. Surface finishes of 4.78, 44.54 and 99.30 microinches produced significantly better ductility and associated break-up times than the 375.65-microinch finish. The baseline production process high-precision liners were measured to have an average surface finish of 44.54 microinches. The results show that for the shaped charge warhead geometry and explosive combination investigated, some care must be taken in respect to surface finish, but that very fine surface finishes do not significantly improve the jet ductility and associated break-up times.

  15. Type of Writing Task and College Students' Meaning Making Following a Romantic Breakup

    ERIC Educational Resources Information Center

    Primeau, Joanna E.; Servaty-Seib, Heather L.; Enersen, Donna

    2013-01-01

    In this study, the authors examined the potential effects of type of writing task (loss/gain vs. general prompt) on the narrative content offered by college students (N = 41) who experienced romantic breakup. Qualitative analyses indicated differences based on type of writing task. Students who received the loss/gain prompt exhibited more…

  16. Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.

  17. Real-Time Characterization of Formation and Breakup of Iridium Clusters in Highly Dealuminated Zeolite Y

    SciTech Connect

    Uzun, Alper; Gates, Bruce C.

    2009-01-15

    The chemistry of formation of iridium clusters from mononuclear iridium diethylene complexes anchored in dealuminated Y zeolite, and their subsequent breakup -- all including changes in the metal-metal, metal-support, and metal-ligand interactions -- is demonstrated by time-resolved EXAFS, XANES, and IR spectroscopy.

  18. DebriSat - A Planned Laboratory-Based Satellite Impact Experiment for Breakup Fragment Characterizations

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Clark, S.; Fitz-Coy, N.; Huynh, T.; Opiela, J.; Polk, M.; Roebuck, B.; Rushing, R.; Sorge, M.; Werremeyer, M.

    2013-01-01

    The goal of the DebriSat project is to characterize fragments generated by a hypervelocity collision involving a modern satellite in low Earth orbit (LEO). The DebriSat project will update and expand upon the information obtained in the 1992 Satellite Orbital Debris Characterization Impact Test (SOCIT), which characterized the breakup of a 1960 s US Navy Transit satellite. There are three phases to this project: the design and fabrication of DebriSat - an engineering model representing a modern, 60-cm/50-kg class LEO satellite; conduction of a laboratory-based hypervelocity impact to catastrophically break up the satellite; and characterization of the properties of breakup fragments down to 2 mm in size. The data obtained, including fragment size, area-to-mass ratio, density, shape, material composition, optical properties, and radar cross-section distributions, will be used to supplement the DoD s and NASA s satellite breakup models to better describe the breakup outcome of a modern satellite.

  19. Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures

    SciTech Connect

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

    2010-11-04

    A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.

  20. Quantifying the thermo-mechanical impact of plume arrival on continental break-up

    NASA Astrophysics Data System (ADS)

    Brune, Sascha; Popov, Anton A.; Sobolev, Stephan V.

    2013-09-01

    The arrival of a plume head at Earth's continental lithosphere is often considered to be an important factor for continental break-up. However, the impact of plume impingement on strength and duration of a rift remains unclear. In this study, we quantify the mechanical and thermal influence of a plume (i.e. lithosphere erosion) on continental break-up. To do that we apply the three-dimensional numerical code SLIM3D that features realistic elasto-visco-plastic rheology. We model the thermo-mechanical response of a segment of Earth's lithosphere that is affected both by extension as well as plume-related lithosphere erosion in order to evaluate the influence on the overall force budget. We find that lithosphere erosion leads to a moderate lithospheric strength reduction of several TN/m. In a force-limited environment, however, this strength reduction may have strong influence on the timing of continental break-up, or it may even control whether continental break-up takes place at all. Additional reduction of the lithospheric strength is likely due to the massive emplacement of dikes that follows intensive melting within the plume head.

  1. An Analysis of Recent Major Breakups in he Low Earth Orbit Region

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Anz-Meador, P. D.

    2010-01-01

    Of the 190 known satellite breakups between 1961 and 2006, only one generated more than 500 cataloged fragments. The event was the explosion of the Pegasus Hydrazine Auxiliary Propulsion System in 1996, adding 713 fragments to the U.S. Satellite Catalog. Since the beginning of 2007; however, the near-Earth environment has been subjected to several major breakups, including the Fengyun-1C anti-satellite test and the explosion of Briz-M in 2007, the unusual breakup of Cosmos 2421 in 2008, and the collision between Iridium 33 and Cosmos 2251 in 2009. Combined, these events added more than 5000 large (> or equal 10 cm) fragments to the environment. Detailed analysis of the radar cross section measurements and orbit histories of the fragments from these major events reveals several unusual characteristics in their size and area-to-mass ratio distributions. The characteristics could be related to the material composition of the parent vehicles, the nature of the breakup, and the composition and physical property of the fragments. In addition, the majority of these fragments are expected to remain in orbit for at least decades. Their long-term impact to the environment is analyzed using the NASA orbital debris evolutionary model, LEGEND. Descriptions of these analyses and a summary are included in this paper.

  2. Systematics of the breakup probability function for 6Li and 7Li projectiles

    NASA Astrophysics Data System (ADS)

    Capurro, O. A.; Pacheco, A. J.; Arazi, A.; Carnelli, P. F. F.; Fernández Niello, J. O.; Martinez Heimann, D.

    2016-01-01

    Experimental non-capture breakup cross sections can be used to determine the probability of projectile and ejectile fragmentation in nuclear reactions involving weakly bound nuclei. Recently, the probability of both type of dissociations has been analyzed in nuclear reactions involving 9Be projectiles onto various heavy targets at sub-barrier energies. In the present work we extend this kind of systematic analysis to the case of 6Li and 7Li projectiles with the purpose of investigating general features of projectile-like breakup probabilities for reactions induced by stable weakly bound nuclei. For that purpose we have obtained the probabilities of projectile and ejectile breakup for a large number of systems, starting from a compilation of the corresponding reported non-capture breakup cross sections. We parametrize the results in accordance with the previous studies for the case of beryllium projectiles, and we discuss their systematic behavior as a function of the projectile, the target mass and the reaction Q-value.

  3. Collision, Coalescence and Breakup of Raindrops. Part II: Parameterization of Fragment Size Distributions.

    NASA Astrophysics Data System (ADS)

    Low, T. B.; List, Roland

    1982-07-01

    The experimental drop collision/breakup results of Low (1977) and Low and List (1982) and McTaggart-Cowan and List (1975b), taken at laboratory pressure and terminal drop speeds, were parameterized for future use in cloud and precipitation modeling. The primary analyses of the 10 representative raindrop pairs were based on the three main geometric shapes generally assumed by the drop pairs after their initial contact and before breakup (or coalescence): filaments, sheets and disks. Relationships for the average total fragment number for each category are given. The fragment number distributions resulting from the collisions in each classification were fitted as sums of normal and log-normal distributions with the parameters of each distribution being related to the drop sizes and physical quantities derived from them (like the collision kinetic energy, CKE).Each collision was then weighted according to the individual contribution and summed to give the probability of occurrence of each breakup type. The weighting functions were based on the CKE of each pair as determined in the center of drop mass frame. With the newly established coalescence efficiencies for raindrop pairs by Low and List (1982) the collision breakup equations were expanded into general overall equations for all drop pairs as expected in natural rain.

  4. Characterization of the 2012-044c Briz-M Upper Stage Breakup

    NASA Technical Reports Server (NTRS)

    Matney, M. J.; Hamilton, Joseph; Papanyan, Valen

    2013-01-01

    On 6 August, 2012, Russia launched two commercial satellites aboard a Proton rocket, and attempted to place them in geosynchronous orbit using a Briz-M upper stage (2012-044C, SSN 38746). Unfortunately, the upper stage failed early in its burn and was left stranded in an elliptical orbit with a perigee in low Earth orbit (LEO). Because the stage failed with much of its fuel on board, it was deemed a significant breakup risk. These fears were confirmed when it broke up 16 October, creating a large cloud of debris with perigees below that of the International Space Station. The debris cloud was tracked by the US Space Surveillance Network (SSN), which can reliably detect and track objects down to about 10 cm in size. Because of the unusual geometry of the breakup, there was an opportunity for NASA Orbital Debris Program Office to request radar assets to characterize the extent of the debris cloud in sizes smaller than the standard debris tracked by the SSN. This paper will describe the observation campaign to measure the small particle distributions of this cloud, and presents the results of the analysis of the data. We shall compare the data to the modelled size distribution, number, and shape of the cloud, and what implications this may have for future breakup debris models. We shall conclude the paper with a discussion how this measurement process can be improved for future breakups.

  5. Bouncing Back from a Breakup: Attachment, Time Perspective, Mental Health, and Romantic Loss

    ERIC Educational Resources Information Center

    Gilbert, Steven P.; Sifers, Sarah K.

    2011-01-01

    Coping with a romantic breakup is a normal developmental task of emerging adulthood. Because of their role in influencing interpersonal relationships and adjustment, attachment history and time perspectives may influence resilience to romantic loss. In an online survey of 1,404 university students ages 18-25 who reported experiencing recent…

  6. Aligning for Innovation - Alignment Strategy to Drive Innovation

    NASA Technical Reports Server (NTRS)

    Johnson, Hurel; Teltschik, David; Bussey, Horace, Jr.; Moy, James

    2010-01-01

    With the sudden need for innovation that will help the country achieve its long-term space exploration objectives, the question of whether NASA is aligned effectively to drive the innovation that it so desperately needs to take space exploration to the next level should be entertained. Authors such as Robert Kaplan and David North have noted that companies that use a formal system for implementing strategy consistently outperform their peers. They have outlined a six-stage management systems model for implementing strategy, which includes the aligning of the organization towards its objectives. This involves the alignment of the organization from the top down. This presentation will explore the impacts of existing U.S. industrial policy on technological innovation; assess the current NASA organizational alignment and its impacts on driving technological innovation; and finally suggest an alternative approach that may drive the innovation needed to take the world to the next level of space exploration, with NASA truly leading the way.

  7. Deformable bearing seat

    NASA Technical Reports Server (NTRS)

    Moreman, O. S., III (Inventor)

    1977-01-01

    A deformable bearing seat is described for seating a bearing assembly in a housing. The seat includes a seating surface in the housing having a first predetermined spheroidal contour when the housing is in an undeformed mode. The seating surface is deformable to a second predetermined spherically contoured surface when the housing is in a deformed mode. The seat is particularly adaptable for application to a rotating blade and mounting ring assembly in a gas turbine engine.

  8. Fusion bonding and alignment fixture

    DOEpatents

    Ackler, Harold D.; Swierkowski, Stefan P.; Tarte, Lisa A.; Hicks, Randall K.

    2000-01-01

    An improved vacuum fusion bonding structure and process for aligned bonding of large area glass plates, patterned with microchannels and access holes and slots, for elevated glass fusion temperatures. Vacuum pumpout of all the components is through the bottom platform which yields an untouched, defect free top surface which greatly improves optical access through this smooth surface. Also, a completely non-adherent interlayer, such as graphite, with alignment and location features is located between the main steel platform and the glass plate pair, which makes large improvements in quality, yield, and ease of use, and enables aligned bonding of very large glass structures.

  9. Adaptive control of molecular alignment

    SciTech Connect

    Horn, C.; Wollenhaupt, M.; Krug, M.; Baumert, T.; Nalda, R. de; Banares, L.

    2006-03-15

    We demonstrate control on nonadiabatic molecular alignment by using a spectrally phase-shaped laser pulse. An evolutionary algorithm in a closed feedback loop has been used in order to find pulse shapes that maximize a given effect. In particular, this scheme has been applied to the optimization of total alignment, and to the control of the temporal structure of the alignment transient within a revival. Asymmetric temporal pulse shapes have been found to be very effective for the latter and have been studied separately in a single-parameter control scheme. Our experimental results are supported by numerical simulations.

  10. Breakup Style and Magmatic Underplating West of the Lofoten Islands, Norway, Based on OBS Data.

    NASA Astrophysics Data System (ADS)

    Breivik, A. J.; Faleide, J. I.; Mjelde, R.; Murai, Y.; Flueh, E. R.

    2014-12-01

    The breakup of the Northeast Atlantic in the Early Eocene was magma-rich, forming the major part of the North Atlantic Igneous Province (NAIP). This is seen as extrusive and intrusive magmatism in the continental domain, and as a thicker than normal oceanic crust produced the first few million years after continental breakup. The maximum magma productivity and the duration of excess magmatism varies along the margins of Northwest Europe and East Greenland, to some extent as a function of the distance from the Iceland hotspot. The Vøring Plateau off mid-Norway is the northernmost of the margin segments in northwestern Europe with extensive magmatism. North of the plateau, magmatism dies off towards the Lofoten Margin, marking the northern boundary of the NAIP here. In 2003, as part of the Euromargins Program we collected an Ocean Bottom Seismometer (OBS) profile from mainland Norway, across the Lofoten Islands, and out into the deep ocean. Forward velocity modeling using raytracing reveals a continental margin that shows transitional features between magma-rich and magma-poor rifting. On one hand, we detect an up to 2 km thick and 40-50 km wide magmatic underplate of the outer continent, on the other hand, continental thinning is greater and intrusive magmatism less than farther south. Continental breakup also appears to be somewhat delayed compared to breakup on the Vøring Plateau, consistent with increased extension. This indicates that magmatic diking, believed to quickly lead to continental breakup of volcanic margins and thus to reduce continental thinning, played a much lesser role here than at the plateau. Early post-breakup oceanic crust is up to 8 km thick, less than half of that observed farther south. The most likely interpretation of these observations, is that the source for the excess magmatism of the NAIP was not present at the Lofoten Margin during rifting, and that the excess magmatism actually observed was the result of lateral transport from the

  11. Sharing Remote and Local Information for Tracking Spring Breakup in the Mackenzie Delta and Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Forbes, D. L.; Whalen, D.; Fraser, P.

    2015-12-01

    The Mackenzie Delta is the second largest on the Arctic Ocean, covering 13 000 km2. The annual flood regime in the delta is dominated by the spring snowmelt freshet and associated ice breakup, as water from the south arrives in the ice-covered delta and spreads over bottomfast and adjacent floating sea ice at the delta front. The complex processes of water-ice interaction, flow partitioning, and overbank flooding to replenish waters in 43 000 delta lakes threaten community, transportation, subsistence, and energy infrastructure in the delta. The annual breakup season is a time of rejuvenation, excitement, and anxiety for delta residents and stakeholders. To track the progress of breakup and meet the need for knowledge dissemination to the local communities, a Mackenzie-Beaufort breakup newsletter has been produced by Natural Resources Canada on a quasi-daily basis during the May-June spring flood season for 10 years, and distributed to an e-mail list that grew to over 300 subscribers. This provides near real-time tracking of water levels and breakup using on-line gauges (Environment Canada), daily MODIS satellite imagery (NASA), Landsat imagery (USGS) and intermittent radar imagery (various sources). In earlier years, information was also supplied from field programs operating in the delta during breakup, but changing priorities and funding have reduced the number of outside researchers present during these critical weeks. Meanwhile the number of local contributors has grown, providing observations and photographs to share with the local, regional and global readership. In this way the newsletter evolved into a two-way communication tool and community portal. The newsletter is a chronicle of each breakup season and a key resource for territorial and municipal managers, subsistence organizations, and emergency response agencies, with routine requests for specific imagery in areas of concern. With the completion of 10 years under the present model, we are exploring

  12. The dynamics of continental breakup-related magmatism on the Norwegian volcanic margin

    NASA Astrophysics Data System (ADS)

    Breivik, A. J.; Faleide, J. I.; Mjelde, R.

    2004-12-01

    The Vøring margin off mid-Norway was initiated during the earliest Eocene (~54 Ma), and large volumes of magmatic rocks were emplaced during and after continental breakup. In 2003, an ocean bottom seismometer survey was acquired on the Norwegian margin to constrain continental breakup and early seafloor spreading processes. The profile P-wave model described here crosses the northern part of the Vøring Plateau. Maximum igneous crustal thickness was found to be 18 km, decreasing to ~6.5 km over ~6 M.y. after continental breakup. Both the volume and the duration of excess magmatism after breakup is about twice of what is observed off the Møre Margin south of the Jan Mayen Fracture Zone, which offsets the margin segments by ~170 km. A similar reduction in magmatism occurs to the north over an along-margin distance of ~100 km to the Lofoten margin, but without a margin offset. There is a strong correlation between magma productivity and early plate spreading rate, which are highest just after breakup, falling with time. This is seen both at the Møre and the Vøring margin segments, suggesting a common cause. A model for the breakup- related magmatism should be able to (1) explain this correlation, (2) the magma production peak at breakup, and (3) the magmatic segmentation. Proposed end-member hypotheses are elevated upper-mantle temperatures caused by a hot mantle plume, or edge-driven small-scale convection fluxing mantle rocks through the melt zone. Both the average P-wave velocity and the major-element data at the Vøring margin indicate a low degree of melting consistent with convection. However, small scale convection does not easily explain the issues listed above. An elaboration of the mantle plume model by N. Sleep, in which buoyant plume material fills the rift-topography at the base of the lithosphere, can explain these: When the continents break apart, the buoyant plume-material flows up into the rift zone, causing excess magmatism by both elevated

  13. The dynamics of continental breakup-related magmatism on the Norwegian volcanic margin

    NASA Astrophysics Data System (ADS)

    Breivik, A. J.; Faleide, J. I.; Mjelde, R.

    2007-12-01

    The Vøring margin off mid-Norway was initiated during the earliest Eocene (~54 Ma), and large volumes of magmatic rocks were emplaced during and after continental breakup. In 2003, an ocean bottom seismometer survey was acquired on the Norwegian margin to constrain continental breakup and early seafloor spreading processes. The profile P-wave model described here crosses the northern part of the Vøring Plateau. Maximum igneous crustal thickness was found to be 18 km, decreasing to ~6.5 km over ~6 M.y. after continental breakup. Both the volume and the duration of excess magmatism after breakup is about twice of what is observed off the Møre Margin south of the Jan Mayen Fracture Zone, which offsets the margin segments by ~170 km. A similar reduction in magmatism occurs to the north over an along-margin distance of ~100 km to the Lofoten margin, but without a margin offset. There is a strong correlation between magma productivity and early plate spreading rate, which are highest just after breakup, falling with time. This is seen both at the Møre and the Vøring margin segments, suggesting a common cause. A model for the breakup- related magmatism should be able to (1) explain this correlation, (2) the magma production peak at breakup, and (3) the magmatic segmentation. Proposed end-member hypotheses are elevated upper-mantle temperatures caused by a hot mantle plume, or edge-driven small-scale convection fluxing mantle rocks through the melt zone. Both the average P-wave velocity and the major-element data at the Vøring margin indicate a low degree of melting consistent with convection. However, small scale convection does not easily explain the issues listed above. An elaboration of the mantle plume model by N. Sleep, in which buoyant plume material fills the rift-topography at the base of the lithosphere, can explain these: When the continents break apart, the buoyant plume-material flows up into the rift zone, causing excess magmatism by both elevated

  14. Imaging of alignment and structural changes of carbon disulfide molecules using ultrafast electron diffraction.

    PubMed

    Yang, Jie; Beck, Joshua; Uiterwaal, Cornelis J; Centurion, Martin

    2015-01-01

    Imaging the structure of molecules in transient-excited states remains a challenge due to the extreme requirements for spatial and temporal resolution. Ultrafast electron diffraction from aligned molecules provides atomic resolution and allows for the retrieval of structural information without the need to rely on theoretical models. Here we use ultrafast electron diffraction from aligned molecules and femtosecond laser mass spectrometry to investigate the dynamics in carbon disulfide following the interaction with an intense femtosecond laser pulse. We observe that the degree of alignment reaches an upper limit at laser intensities below the ionization threshold, and find evidence of structural deformation, dissociation and ionization at higher laser intensities. PMID:26337631

  15. Deformed discrete symmetries

    NASA Astrophysics Data System (ADS)

    Arzano, Michele; Kowalski-Glikman, Jerzy

    2016-09-01

    We construct discrete symmetry transformations for deformed relativistic kinematics based on group valued momenta. We focus on the specific example of κ-deformations of the Poincaré algebra with associated momenta living on (a sub-manifold of) de Sitter space. Our approach relies on the description of quantum states constructed from deformed kinematics and the observable charges associated with them. The results we present provide the first step towards the analysis of experimental bounds on the deformation parameter κ to be derived via precision measurements of discrete symmetries and CPT.

  16. Fluctuations as stochastic deformation.

    PubMed

    Kazinski, P O

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium. PMID:18517590

  17. Fluctuations as stochastic deformation

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  18. Atmospheric breakup of a small comet in the Earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Teterev, A. V.; Misychenko, N. I.; Rudak, L. V.; Romanov, G. S.; Smetannikov, A. S.; Nemchinov, I. V.

    1993-01-01

    The aerodynamic stresses can lead to the deformation and even to destruction of the meteoroids during their flight through the atmosphere. The pressure at the blunt nose of the cosmic body moving at very high speed through the dense layers of the atmosphere may be much larger than the tensile or the compressive strength of the body. So the usage of the hydrodynamics theory is validated. The estimates show that the transverse velocity of the substance of the body U is of the order of (rho(sub a)/rho(sub o))(sup 1/2)V where V is the velocity of the body and rho(sub o) is its density, rho(sub a) is the density of the atmosphere. The separation of the fragments is larger than the diameter of the body D if D is less than D(sub c) = 2H(square root of rho(sub a)/rho(sub o)), where H is the characteristic scale of the atmosphere. For an icy body one obtains U = 1/30(V) and critical diameter D(sub C) = 500 m. The process of the disintegration of the body is still not fully understood and so one can use the numerical simulation to investigate it. Such simulations where conducted for the Venusian atmosphere and the gaseous equation of state of the body was used. For the Earth atmosphere for the velocity V = 50 km/s the pressure at the blunt nose of the body is 25 kbar, and is of the order of bulk modulus of compressibility of the water or ice. The realistic EOS of water in tabular form was used. It was assumed that the initial shape of the body was spherical and the initial diameter D(sub o) of the body is 200 m and so it is smaller than the critical diameter D(sub C). The initial kinetic energy of the icy body is equivalent to the energy of the explosion 1200 Mt of TNT. The results of the simulation of the deformation of the body during its vertical flight through the atmosphere and during its impact into the ocean are presented.

  19. Monitoring ice break-up on the Mackenzie River, Canada, from MODIS Aqua and Terra observations

    NASA Astrophysics Data System (ADS)

    Muhammad, P.; Duguay, C. R.; Kang, K.

    2013-12-01

    Monitoring the response of river ice phenology to variability and changes in high-latitude climate conditions is critical for improving our understanding of northern hydrology and related impacts on geochemical and biological processes. Shorter ice cover duration, thinner ice, and earlier break-up also influence the winter road season, thereby influencing industrial development and the delivery of goods to northern communities. Increased upstream temperatures over the Mackenzie River Basin have caused shorter ice cover seasons, consequently changing the timing and severity of river ice flow in this high-latitude region. This study involves the analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) Level 3 500-m snow products (Aqua and Terra), complemented with 250-m Level 1b data, to monitor ice cover during the break-up period on the Mackenzie River over the 2001-2013 period. Results from the analysis of 10 ice seasons (2003-2012) show that first day ice-off was observed between day of year (DY) 115-125 and ended between DY 145-155, resulting in average melt durations of about 30-40 days. Additional ice-on and ice-off days observed during 2003-2012 resulted from northern flowing entrained river ice that extended the break-up season until DY 155-163. Floating ice flowing northbound could therefore generate multiple periods of ice-cover and ice-free days at the same geographic location. During the ice break-up seasons from 2003-2012, ice melt was initiated by in situ melt over drainage basin (thermodynamic), especially between 61-62o N. However, ice break-up above the 62o N was more dynamically driven. In addition, ice jams were found to be largely controlled by river morphology.

  20. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, Charles R.; Hammond, Robert B.

    1981-01-01

    The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

  1. Laser beam alignment apparatus and method

    DOEpatents

    Gruhn, C.R.; Hammond, R.B.

    The disclosure related to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.

  2. Theory of grain alignment in molecular clouds

    NASA Technical Reports Server (NTRS)

    Roberge, Wayne G.

    1993-01-01

    Research accomplishments are presented and include the following: (1) mathematical theory of grain alignment; (2) super-paramagnetic alignment of molecular cloud grains; and (3) theory of grain alignment by ambipolar diffusion.

  3. Protein structure alignment beyond spatial proximity

    PubMed Central

    Wang, Sheng; Ma, Jianzhu; Peng, Jian; Xu, Jinbo

    2013-01-01

    Protein structure alignment is a fundamental problem in computational structure biology. Many programs have been developed for automatic protein structure alignment, but most of them align two protein structures purely based upon geometric similarity without considering evolutionary and functional relationship. As such, these programs may generate structure alignments which are not very biologically meaningful from the evolutionary perspective. This paper presents a novel method DeepAlign for automatic pairwise protein structure alignment. DeepAlign aligns two protein structures using not only spatial proximity of equivalent residues (after rigid-body superposition), but also evolutionary relationship and hydrogen-bonding similarity. Experimental results show that DeepAlign can generate structure alignments much more consistent with manually-curated alignments than other automatic tools especially when proteins under consideration are remote homologs. These results imply that in addition to geometric similarity, evolutionary information and hydrogen-bonding similarity are essential to aligning two protein structures. PMID:23486213

  4. Liquid Crystal Research Shows Deformation By Drying

    NASA Technical Reports Server (NTRS)

    2003-01-01

    These images, from David Weitz's liquid crystal research, show ordered uniform sized droplets (upper left) before they are dried from their solution. After the droplets are dried (upper right), they are viewed with crossed polarizers that show the deformation caused by drying, a process that orients the bipolar structure of the liquid crystal within the droplets. When an electric field is applied to the dried droplets (lower left), and then increased (lower right), the liquid crystal within the droplets switches its alignment, thereby reducing the amount of light that can be scattered by the droplets when a beam is shone through them.

  5. Fixture for aligning motor assembly

    DOEpatents

    Shervington, Roger M.; Vaghani, Vallabh V.; Vanek, Laurence D.; Christensen, Scott A.

    2009-12-08

    An alignment fixture includes a rotor fixture, a stator fixture and a sensor system which measures a rotational displacement therebetween. The fixture precisely measures rotation of a generator stator assembly away from a NULL position referenced by a unique reference spline on the rotor shaft. By providing an adjustable location of the stator assembly within the housing, the magnetic axes within each generator shall be aligned to a predetermined and controlled tolerance between the generator interface mounting pin and the reference spline on the rotor shaft. Once magnetically aligned, each generator is essentially a line replaceable unit which may be readily mounted to any input of a multi-generator gearbox assembly with the assurance that the magnetic alignment will be within a predetermined tolerance.

  6. Vector correlations and alignment parameters in the photodissociation of HF and DF

    NASA Astrophysics Data System (ADS)

    Balint-Kurti, G. G.; Orr-Ewing, A. J.; Beswick, J. A.; Brown, Alex; Vasyutinskii, O. S.

    2002-06-01

    Orientation and alignment parameters have been computed from first principles for the photodissociation of the HF and DF diatomic molecules. The calculations are entirely ab initio and the break-up dynamics of the molecule is treated rigorously taking account of the electronically nonadiabatic dynamics on three coupled adiabatic electronic potential energy curves. The potential energy curves and spin-orbit interactions, which have been previously reported [J. Chem. Phys. 113, 1870 (2000)], are computed using ab initio molecular electronic structure computer codes. These are then used to compute photofragmentation T matrix elements using a time-dependent quantum mechanical wave packet treatment and from these a complete set of anisotropy parameters with rank up to K=3 is computed. The predicted vector correlations and alignment parameters are presented as a function of energy for HF and DF initially in both their ground and first excited vibrational states. The parameters predicted for the molecules which are initially in their excited vibrational states display a pronounced sharp energy dependence arising from the nodal structure of the initial vibrational wavefunction. The theoretical results are analyzed using a simple model of the dynamics and it is demonstrated how the magnitude and relative phases of the photofragmentation T matrix elements can be deduced from the experimentally measured alignment parameters. No experimental measurements have yet been made of alignment parameters for hydrogen halide diatomics and the present results provide the first predictions of these quantities which may be compared with future experimental observations.

  7. Well-pump alignment system

    DOEpatents

    Drumheller, D.S.

    1998-10-20

    An improved well-pump for geothermal wells, an alignment system for a well-pump, and to a method for aligning a rotor and stator within a well-pump are disclosed, wherein the well-pump has a whistle assembly formed at a bottom portion thereof, such that variations in the frequency of the whistle, indicating misalignment, may be monitored during pumping. 6 figs.

  8. Two-valued breakup length of a water jet issuing from a finite-length nozzle under normal gravity.

    PubMed

    Umemura, Akira; Kawanabe, Sho; Suzuki, Sousuke; Osaka, Jun

    2011-09-01

    Laboratory experiments are conducted in which water is issued vertically downward from a finite-length nozzle at a constant speed using a piston. The results of these experiments indicate that the breakup length of the liquid jet is two-valued at Weber numbers greater than unity but less than a certain value, which depends on the nozzle length-to-radius ratio and the Bond number. In addition to a long breakup length, which is consistent with the conventional observation, another shorter breakup length is realized at the same jet issue speed. Each experimental run for a specific jet issue speed begins from the start of liquid issue so that each run is independent of the other runs. Transition between the two breakup lengths seldom occurs in each run. Which of the two breakup lengths occurs is determined at the start of liquid issue, when the capillary wave produced by the liquid jet tip contraction easily reaches the nozzle exit. Unlike the conventional belief, which is based on the Plateau-Rayleigh instability theory, this experimental evidence demonstrates that liquid jet disintegration occurs in a deterministic manner. The previously proposed self-destabilizing mechanism of a liquid jet in microgravity, in which the origin of the unstable wave responsible for the breakups is attributed to the formation of an upstream propagating capillary wave at every breakup, is extended to explore the physics underlying the observed liquid jet disintegration behaviors. PMID:22060494

  9. Surface motions and intraplate continental deformation in Alaska driven by mantle flow

    NASA Astrophysics Data System (ADS)

    Finzel, Emily S.; Flesch, Lucy M.; Ridgway, Kenneth D.; Holt, William E.; Ghosh, Attreyee

    2015-06-01

    The degree to which the lithosphere and mantle are coupled and contribute to surface deformation beneath continental regions remains a fundamental question in the field of geodynamics. Here we use a new approach with a surface deformation field constrained by GPS, geologic, and seismicity data, together with a lithospheric geodynamic model, to solve for tractions inferred to be generated by mantle convection that (1) drive extension within interior Alaska generating southward directed surface motions toward the southern convergent plate boundary, (2) result in accommodation of the relative motions between the Pacific and North America in a comparatively small zone near the plate boundary, and (3) generate the observed convergence within the North American plate interior in the Mackenzie mountains in northwestern Canada. The evidence for deeper mantle influence on surface deformation beneath a continental region suggests that this mechanism may be an important contributing driver to continental plate assemblage and breakup.

  10. Projection-Based Volume Alignment

    PubMed Central

    Yu, Lingbo; Snapp, Robert R.; Ruiz, Teresa; Radermacher, Michael

    2013-01-01

    When heterogeneous samples of macromolecular assemblies are being examined by 3D electron microscopy (3DEM), often multiple reconstructions are obtained. For example, subtomograms of individual particles can be acquired from tomography, or volumes of multiple 2D classes can be obtained by random conical tilt reconstruction. Of these, similar volumes can be averaged to achieve higher resolution. Volume alignment is an essential step before 3D classification and averaging. Here we present a projection-based volume alignment (PBVA) algorithm. We select a set of projections to represent the reference volume and align them to a second volume. Projection alignment is achieved by maximizing the cross-correlation function with respect to rotation and translation parameters. If data are missing, the cross-correlation functions are normalized accordingly. Accurate alignments are obtained by averaging and quadratic interpolation of the cross-correlation maximum. Comparisons of the computation time between PBVA and traditional 3D cross-correlation methods demonstrate that PBVA outperforms the traditional methods. Performance tests were carried out with different signal-to-noise ratios using modeled noise and with different percentages of missing data using a cryo-EM dataset. All tests show that the algorithm is robust and highly accurate. PBVA was applied to align the reconstructions of a subcomplex of the NADH: ubiquinone oxidoreductase (Complex I) from the yeast Yarrowia lipolytica, followed by classification and averaging. PMID:23410725

  11. Binocular collimation vs conditional alignment

    NASA Astrophysics Data System (ADS)

    Cook, William J.

    2012-10-01

    As binocular enthusiasts share their passion, topics related to collimation abound. Typically, we find how observers, armed only with a jeweler's screwdriver, can "perfectly collimate" his or her binocular, make it "spot on," or other verbiage of similar connotation. Unfortunately, what most are addressing is a form of pseudo-collimation I have referred to since the mid-1970s as "Conditional Alignment." Ignoring the importance of the mechanical axis (hinge) in the alignment process, this "condition," while having the potential to make alignment serviceable, or even outstanding—within a small range of IPD (Interpupillary Distance) settings relative to the user's spatial accommodation (the ability to accept small errors in parallelism of the optical axes)—may take the instrument farther from the 3-axis collimation conscientious manufacturers seek to implement. Becoming more optically savvy—and especially with so many mechanically inferior binoculars entering the marketplace— the consumer contemplating self-repair and alignment has a need to understand the difference between clinical, 3-axis "collimation" (meaning both optical axes are parallel with the axis of the hinge) and "conditional alignment," as differentiated in this paper. Furthermore, I believe there has been a long-standing need for the term "Conditional Alignment," or some equivalent, to be accepted as part of the vernacular of those who use binoculars extensively, whether for professional or recreational activities. Achieving that acceptance is the aim of this paper.

  12. Primary mirror alignment and assembly for a multispectral space telescope

    NASA Astrophysics Data System (ADS)

    Lin, Wei-Cheng; Chang, Shenq-Tsong; Chang, Sheng-Hsiung; Chang, Chen-Peng; Lin, Yu-Chuan; Huang, Po-Hsuan; Tsay, Ho-Lin; Chin, Chi-Chieh; Pan, Hsu-Pin; Huang, Ting-Ming

    2013-10-01

    For a currently developing multispectral space Cassegrain telescope, the primary mirror with 450 mm clear aperture is made of Zerodur and lightweighted at a ratio about 50 % to meet both thermal and mass requirement. For this mirror, it is critical to reduce the astigmatism caused from the gravity effect, bonding process and the deformation from the mounting to the main structure of the telescope (main plate). In this article, the primary mirror alignment, MGSE, assembly process and the optical performance test for the primary mirror assembly are presented. The mechanical shim is the interface between the iso-static mount and main plate. It is used to compensate the manufacture errors of components and differences of local co-planarity errors to prevent the stress while iso-static mount (ISM) is screwed to main plate. After primary mirror assembly, an optical performance test method called bench test with novel algorithm is used to analyze the astigmatism caused from the gravity effect and the deformation from the mounting or supporter. In an effort to achieve the requirement for the tolerance in primary mirror assembly, the astigmatism caused from the gravity and deformation by the mounting force could be less than P-V 0.02λ at 633 nm. The consequence of these demonstrations indicates that the designed mechanical ground supported equipment (MGSE) for the alignment and assembly processes meet the critical requirements for primary mirror assembly of the telescope.

  13. BinAligner: a heuristic method to align biological networks.

    PubMed

    Yang, Jialiang; Li, Jun; Grünewald, Stefan; Wan, Xiu-Feng

    2013-01-01

    The advances in high throughput omics technologies have made it possible to characterize molecular interactions within and across various species. Alignments and comparison of molecular networks across species will help detect orthologs and conserved functional modules and provide insights on the evolutionary relationships of the compared species. However, such analyses are not trivial due to the complexity of network and high computational cost. Here we develop a mixture of global and local algorithm, BinAligner, for network alignments. Based on the hypotheses that the similarity between two vertices across networks would be context dependent and that the information from the edges and the structures of subnetworks can be more informative than vertices alone, two scoring schema, 1-neighborhood subnetwork and graphlet, were introduced to derive the scoring matrices between networks, besides the commonly used scoring scheme from vertices. Then the alignment problem is formulated as an assignment problem, which is solved by the combinatorial optimization algorithm, such as the Hungarian method. The proposed algorithm was applied and validated in aligning the protein-protein interaction network of Kaposi's sarcoma associated herpesvirus (KSHV) and that of varicella zoster virus (VZV). Interestingly, we identified several putative functional orthologous proteins with similar functions but very low sequence similarity between the two viruses. For example, KSHV open reading frame 56 (ORF56) and VZV ORF55 are helicase-primase subunits with sequence identity 14.6%, and KSHV ORF75 and VZV ORF44 are tegument proteins with sequence identity 15.3%. These functional pairs can not be identified if one restricts the alignment into orthologous protein pairs. In addition, BinAligner identified a conserved pathway between two viruses, which consists of 7 orthologous protein pairs and these proteins are connected by conserved links. This pathway might be crucial for virus packing and

  14. Resurgent deformation quantisation

    SciTech Connect

    Garay, Mauricio; Goursac, Axel de; Straten, Duco van

    2014-03-15

    We construct a version of the complex Heisenberg algebra based on the idea of endless analytic continuation. The algebra would be large enough to capture quantum effects that escape ordinary formal deformation quantisation. -- Highlights: •We construct resurgent deformation quantisation. •We give integral formulæ. •We compute examples which show that hypergeometric functions appear naturally in quantum computations.

  15. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  16. Continental Break-up and the dynamics of rifting in backarc basins : the Gulf of Lions margin

    NASA Astrophysics Data System (ADS)

    Jolivet, L.; Gorini, C.; Bache, F.; Smit, J.; Leroy, S.

    2012-04-01

    Deep seismic profiles and subsidence history of the Gulf of Lions margin reveal a non-classical evolution with intense stretching of the distal margin and delayed subsidence, despite a rather weak extension of the onshore and shallow offshore portion of the margin. The interpretation of an unpublished MCS profile (TGS-NOPEC) and published geophysical data leads us to revisit this evolution. The 70 km-long domain of extremely thinned continental crust, the GoL MCC, has been extracted from below the margin by the south-eastward flow of hot asthenosphere in the backarc region during rollback of the Apennines slab. The combination of Eocene crustal thickening related to formation of the Pyrenees and the nearby volcanic arc and associated hot asthenosphere makes the upper mantle and the lower crust weak enough to flow south-eastward entrained by the underlying asthenospheric flow due to slab retreat. The upper crust, more resistant, has been left behind and was only moderately thinned. The overall hot geodynamic environment also explains the subaerial conditions during most of the rifting stage and the delayed subsidence after the breakup. The efficiency of such a basal drag is not ascertained and it should certainly be further tested but, in the Mediterranean backarc regions, the coupling between asthenospheric and lower crustal deformation seems quite strong as suggested by the comparison of stretching directions in MCCs and seismic anisotropy of SKS waves which suggests that shear stresses due to asthenospheric flow toward retreating subduction zones can be transmitted up to the lower crust. This model cannot be simply used for Atlantic-type passive margins because they usually do not show exhumed lower crust within the continent-ocean transition but the role that an astheospheric flow could play during rifting should be looked at.

  17. Continental rift evolution: From rift initiation to incipient break-up in the Main Ethiopian Rift, East Africa

    NASA Astrophysics Data System (ADS)

    Corti, Giacomo

    2009-09-01

    The Main Ethiopian Rift is a key sector of the East African Rift System that connects the Afar depression, at Red Sea-Gulf of Aden junction, with the Turkana depression and Kenya Rift to the South. It is a magmatic rift that records all the different stages of rift evolution from rift initiation to break-up and incipient oceanic spreading: it is thus an ideal place to analyse the evolution of continental extension, the rupture of lithospheric plates and the dynamics by which distributed continental deformation is progressively focused at oceanic spreading centres. The first tectono-magmatic event related to the Tertiary rifting was the eruption of voluminous flood basalts that apparently occurred in a rather short time interval at around 30 Ma; strong plateau uplift, which resulted in the development of the Ethiopian and Somalian plateaus now surrounding the rift valley, has been suggested to have initiated contemporaneously or shortly after the extensive flood-basalt volcanism, although its exact timing remains controversial. Voluminous volcanism and uplift started prior to the main rifting phases, suggesting a mantle plume influence on the Tertiary deformation in East Africa. Different plume hypothesis have been suggested, with recent models indicating the existence of deep superplume originating at the core-mantle boundary beneath southern Africa, rising in a north-northeastward direction toward eastern Africa, and feeding multiple plume stems in the upper mantle. However, the existence of this whole-mantle feature and its possible connection with Tertiary rifting are highly debated. The main rifting phases started diachronously along the MER in the Mio-Pliocene; rift propagation was not a smooth process but rather a process with punctuated episodes of extension and relative quiescence. Rift location was most probably controlled by the reactivation of a lithospheric-scale pre-Cambrian weakness; the orientation of this weakness (roughly NE-SW) and the Late

  18. Radar Image and Rain-gauge Alignment using the Multi-resolution Viscous Alignment (MVA) Algorithm

    NASA Astrophysics Data System (ADS)

    Chatdarong, V.

    2007-12-01

    Rainfall is a complex environmental variable that is difficult to describe either deterministically or statistically. To understand rainfall behaviors, many types of instruments are employed to detect and collect rainfall information. Among them, radar seems to provide the most comprehensive rainfall measurement at fine spatial and temporal resolution and over a relatively wide area. Nevertheless, it does not detects surface rainfall directly like what rain-gauge does. The accuracy radar rainfall, therefore, depends greatly on the Z-R relationship which convert radar reflectivity (Z) to surface rainrate (R). This calibration is usually done by fitting the rain-gauge data with the corresponding radar reflectivity using the regression analysis. To best fit the data, the radar reflectivity at neighbor pixels are usually used to best match the rain-gauge data. However, when applying the Z-R relationship to the radar image, there is no position adjustment despite the calibration technique. Hence, it is desirable to adjust the position of the radar reflectivity images prior to applying the Z-R relationship to improve the accuracy of the rainfall estimation. In this research, the Multi-resolution Viscous Alignment (MVA) algorithm is applied to best align radar reflectivity images to rain-gauge data in order to improve rainfall estimation from the Z-R relationship. The MVA algorithm solves the motion estimation problems using a Bayesian formulation to minimize misfits between two data sets. In general, the problem are ill-posed; therefore, some regularizations and constraints based on smoothness and non-divergence assumptions are employed. This algorithm is superior to the conventional techniques and correlation based techniques. It is fast, robust, easy to implement, and does not require data training. In addition, it can handle higher-order, missing data, and small-scale deformations. The algorithm provides spatially dense, consistency, and smooth transition vector. The

  19. Receiver function and magnetotelluric analysis to understand the first stage of a continental lithospheric break-up : case of the North Tanzanian Rift

    NASA Astrophysics Data System (ADS)

    Plasman, M.; Tiberi, C.; Tarits, P.; Hautot, S.; Gautier, S.; Ebinger, C. J.; Mulibo, G. D.; Khalfan, M.

    2015-12-01

    First stage of continental break-up, though intensively studied, is yet poorly understood. This is partly because actual rifting areas are either too mature (more than 10 My) or not easily accessible (thick sediment cover or under water). The North Tanzania part of the East African Rift is the place of a lithosphere's early break-up (less than 5My) in response to a combination of regional pulling forces and mantle upwelling. Deformation there results from complex interactions between magmatic intrusions, faulting, asthenospheric dynamics and far field stresses. CoLiBrEA (ANR) and CRAFTI (NSF) are two multidisciplinary projects which collaboratively focus on this area to understand the interactions between faults and magma, the role of inherited structures and rheological heterogeneities of the lithosphere. For that purpose, we deployed 38 broadband seismic stations in the Natron and Ngorongoro areas from January 2013 to December 2014 and carried out a 120 km East-West magnetotelluric (MT) profile to image the crustal and mantle structures. The 3D resistivity model, obtained from the inversion of the MT data along the profile, shows an highly heterogeneous crust with three-dimensional structures over a more homogeneous upper mantle. The first inversion result from the receiver function (RF) by the Zhu and Kanamori's inversion method show a thick crust (~35 km) with important variations (maximum 15km) especially in the Ngorongoro area, and an average Vp/Vs ratio of 1.75. We then completed this study by combining the MT data and the RF at the 11 sites of the EW profile. For each site, we built a 1D velocity model (Vs and VpVs) obtained by combining the Sambridge forward solution with a non linear descent research algorithm and constrained by the resistivity structure. The inversion shows an heterogeneous crust obviously dominated by the Moho interface at different depths, with low velocity layers mainly corresponding to low resistivity features.

  20. Pre-breakup geology of the Gulf of Mexico-Caribbean: Its relation to Triassic and Jurassic rift systems of the region

    SciTech Connect

    Bartok, P. )

    1993-02-01

    A review of the pre-breakup geology of west-central Pangea, comprised of northern South America, Gulf of Mexico and West Africa, combined with a study of the Mesozoic rift trends of the region confirms a relation between the rift systems and the underlying older grain of deformation. The pre-breakup analysis focuses attention on the Precambrian, Early Paleozoic and Late Paleozoic tectonic events affecting the region and assumes a Pindell fit. Two Late Precambrian orogenic belts are observed in the west central Pangea. Along the northern South American margin and Yucatan a paleo northeast trending Pan-African aged fold belt is documented. A second system is observed along West Africa extending from the High Atlas to the Mauritanides and Rockelides. During the Late Paleozoic, renewed orogenic activity, associated with the Gondwana/Laurentia suture, affected large segments of west central Pangea. The general trend of the system is northeast-southwest and essentially parallels the Gyayana Shield, West African, and eastern North American cratons. Mesozoic rifting closely followed either the Precambrian trends or the Late Paleozoic orogenic belt. The Triassic component focuses along the western portions of the Gulf of Mexico continuing into eastern Mexico and western South America. The Jurassic rift trend followed along the separation between Yucatan and northern South America. At Lake Maracaibo the Jurassic rift system eventually overlaps the Triassic rifts. The Jurassic rift resulted in the [open quotes]Hispanic Corridor[close quotes] that permitted Tethyan and Pacific marine faunas to mix at a time when the Gulf of Mexico underwent continental sedimentation.

  1. Alignment and Load Transfer in Carbon Nanotube and Dicyclopentadiene Composites

    NASA Astrophysics Data System (ADS)

    Severino, Joseph Vincent

    Individual carbon nanotubes (CNTs) are the strongest materials available but their macroscopic assemblies are weak. This work establishes a new thermosetting dicyclopentadiene (DCPD) and CNT composite that increases the strength of CNT assemblies. These high volume fraction and void free structures constitute advanced materials that could one day replace traditional composite systems. To further the understanding of physical interactions between polymer and CNTs, a novel "capstan" load transfer mechanism is also introduced. Self-supporting assemblies of interconnected carbon nanotubes were stretched, twisted and compressed to fashion composites by the infusion and polymerization of low viscosity DCPD based monomeric resins. The properties of the CNTs, polymer and composite were characterized with thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA) and Raman spectroscopy. The microstructure was analyzed by wide angle X-ray scattering (WAXS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Sheets were drawn at 15 m/min from a growth furnace to impart alignment then stretched to further modify alignment. The mechanical properties were determined in five orientations with respect to the growth direction. The strength was nearly three times higher along this growth direction than it was perpendicular, and modulus was nearly six times higher. Transverse stretching achieved 1.5 times the elongation but alignment was inferior due to CNT kinking that prevented alignment and consolidation. Composites yarns and sheets were investigated for the mechanical properties, microstructure and load transfer. The DCPD resin was found to wet the CNTs and lubricated deformation. This reduced loads during processing, and curing solidified the aligned and consolidated structure. The stretched and twisted composite yarns increased the failure stress 51%. In aligned composite sheet, the failure stress increased 200%. The increased stresses

  2. Constraining lithosphere deformation mode evolution for the Iberia-Newfoundland rifted margins

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The deformation of lithosphere and asthenosphere and its evolution during continental rifting leading to breakup and seafloor spreading initiation is poorly understood. The resulting margin architecture and OCT structure is complex and diverse, and observations at magma poor margins includes hyper-extended continental crust and lithosphere, detachments faults, exhumed mantle, continental slivers and scattered embryonic oceanic crust. A coupled kinematic-dynamic model of lithosphere and asthenosphere deformation has been used to investigate the sequence of lithosphere deformation modes for 2 conjugate margin profiles for the Iberia-Newfoundland rifted margins. We use the observed water-loaded subsidence and crustal thickness, together with subsidence history and the age of melt generation, to test and constrain lithosphere and asthenosphere deformation models. A sequence of lithosphere deformation modes is represented by a succession of flow-fields, which are generated by a 2D finite element viscous flow model (FE-Margin), and is 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 (e.g. Braun et al. 2000) is also kinematically included. The methodology of Katz et al., 2003 is used to predict melt generation by decompressional melting. The magnitude of extension used in the modelling is consistent with that proposed by 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

  3. 3D microband boundary alignments and transitions in a cold rolled commercial purity aluminum alloy

    SciTech Connect

    George, C.; Soe, B.; King, K.; Quadir, M.Z.; Ferry, M.; Bassman, L.

    2013-05-15

    In the study of microband formation during plastic deformation of face centered cubic metals and alloys, two theories have been proposed regarding the orientations of their boundaries: (i) they are aligned parallel to crystallographic planes associated with dislocation glide (i.e. (111) planes in FCC metals), or (ii) they are aligned in accordance with the macroscopic stress state generated during deformation. In this study, high resolution 3D electron backscatter diffraction (3D EBSD) was used to investigate the morphology and crystallographic nature of microband boundaries within a 19 × 9 × 8.6 μm volume of a deformed grain in commercial purity aluminum cold rolled to 22% reduction. It was found that microband boundaries correspond to both theories of orientation. Additionally, a single surface may contain both crystallographic and non-crystallographic alignments. Misorientations across boundaries in the regions of microband triple junctions have been identified for both boundary alignments. - Highlights: ► Reconstruction of a 3D volume of crystallographic orientations from EBSD data ► Subgrain features accurately reconstructed using specially designed strategies. ► Microband boundaries contain crystallographic and non-crystallographic alignments. ► Boundaries form by crystallographic process but rotate to non-crystallographic.

  4. SU-E-J-105: Trusting Dose Deformation and Accumulation for GYN Brachytherapy

    SciTech Connect

    Poplawski, L; Li, T; Chino, J; Craciunescu, O

    2015-06-15

    Purpose: In brachytherapy, structures surrounding the target have the potential to move between treatments and receive unknown dose. Deformable image registration could overcome challenges through dose accumulation. This study uses two possible deformable dose summation techniques and compares the results to point dose summation currently performed in clinic. Methods: Data for ten patients treated with a Syed template was imported into the MIM software (Cleveland, OH). The deformable registration was applied to structures by masking other image data to a single intensity. The registration flow consisted of the following steps: 1) mask CTs so that each of the structures-of-interest had one unique intensity; 2) perform applicator — based rigid registration; 3) Perform deformable registration; 4) Refine registration by changing local alignments manually; 5) Repeat steps 1 to 3 until desired structure adequately deformed; 5) Transfer each deformed contours to the first CT. The deformed structure accuracy was determined by a dice similarity coefficient (DSC) comparison with the first fraction. Two dose summation techniques were investigated: a deformation and recalculation on the structure; and a dose deformation and accumulation method. Point doses were used as a comparison value. Results: The Syed deformations have DSC ranging from 0.53 to 0.97 and 0.75 and 0.95 for the bladder and rectum, respectively. For the bladder, contour deformation addition ranged from −34.8% to 0.98% and dose deformation accumulation ranged from −35% to 29.3% difference from clinical calculations. For the rectum, contour deformation addition ranged from −5.2% to 16.9% and the dose deformation accumulation ranged from −29.1% to 15.3% change. Conclusion: Deforming dose for summation leads to different volumetric doses than when dose is recalculated on deformed structures, raising concerns about the accuracy of the deformed dose. DSC alone cannot be used to establish the accuracy of a

  5. A Nonlinear Observer for Gyro Alignment Estimation

    NASA Technical Reports Server (NTRS)

    Thienel, J.; Sanner, R. M.

    2003-01-01

    A nonlinear observer for gyro alignment estimation is presented. The observer is composed of two error terms, an attitude error and an alignment error. The observer is globally stable with exponential convergence of the attitude errors. The gyro alignment estimate converges to the true alignment when the system is completely observable.

  6. Global Alignment System for Large Genomic Sequencing

    Energy Science and Technology Software Center (ESTSC)

    2002-03-01

    AVID is a global alignment system tailored for the alignment of large genomic sequences up to megabases in length. Features include the possibility of one sequence being in draft form, fast alignment, robustness and accuracy. The method is an anchor based alignment using maximal matches derived from suffix trees.

  7. Deformation T-Cup: A new Kawai-style deformation device capable of controlled strain-rate deformation at pressures in excess of 20 GPa

    NASA Astrophysics Data System (ADS)

    Hunt, S. A.; Dobson, D. P.; Santangeli, J. R.; McCormack, R.; Li, L.; Whitaker, M. L.; Vaughan, M. T.; Weidner, D. J.

    2012-12-01

    A significant proportion of our understanding of the rheological properties of mantle minerals is gained by analysing the data from, both offline and synchrotron based, controlled strain-rate deformation experiments. However, controlled strain-rate deformation experiments at in-situ conditions have been limited by the current generation of deformation apparatus (the deformation-DIA and the Rotational Drickamer) to about 15 GPa. Being limited to 15 GPa means that in situ deformation experiments are limited to phases stable in the upper mantle and the upper parts of the transition-zone. Therefore, deformation experiments on mantle composition ringwoodite and majorite have not been performed in significant numbers and there are no measurements at controlled strain-rates of the lower-mantle perovskites. Here, we report the capabilities of a new device the DT-cup or deformation T-Cup, which is capable for deformation experiments at pressures in excess of 20 GPa, and with continued development in excess of 25 GPa. The two instances of the DT-Cup press at University College London and the X17B2 beamline at the NSLS, consist of 400 tonne, Paris-Edinburgh style, load frames into which split-cylinder 6-8 multi-anvil tooling is inserted, with the <111> axis of the inner cube set aligned with the action of the press. The 'top' and 'bottom' anvils of the cube set are replaced by hexagonal rods, cut so the end of the rods are the same shape as the inner faces of the 10 (X17B2 device) or 14 mm (UCL device) edge length cubes they replace. Controlled strain-rate deformation of the sample is undertaken by differential pistons pushing on the two hexagonal rams and advancing the two anvils along the aligned <111> axis of the inner cube set. As the pistons advance the main ram adjusts in order that the confining pressure exerted on the sample remains constant. The differences between the standard Kawai-style split cylinder devices and the DT-Cup are analogous to the differences between

  8. Single-stage Anterior and Posterior Fusion Surgery for Correction of Cervical Kyphotic Deformity Using Intervertebral Cages and Cervical Lateral Mass Screws: Postoperative Changes in Total Spine Sagittal Alignment in Three Cases with a Minimum Follow-up of Five Years.

    PubMed

    Ogihara, Satoshi; Kunogi, Junichi

    2015-01-01

    The surgical treatment of cervical kyphotic deformity remains challenging. As a surgical method that is safer and avoids major complications, the authors present a procedure of single-stage anterior and posterior fusion to correct cervical kyphosis using anterior interbody fusion cages without plating, as illustrated by three consecutive cases. Case 1 was a 78-year-old woman who presented with a dropped head caused by degeneration of her cervical spine. Case 2 was a 54-year-old woman with athetoid cerebral palsy. She presented with cervical myelopathy and cervical kyphosis. Case 3 was a 71-year-old woman with cervical kyphotic deformity following a laminectomy. All three patients underwent anterior release and interbody fusion with cages and posterior fusion with cervical lateral mass screw (LMS) fixation. Postoperative radiographs showed that correction of kyphosis was 39° in case 1, 43° in case 2, and 39° in case 3. In all three cases, improvement of symptoms was established without major perioperative complications, solid fusion was achieved, and no loss of correction was observed at a minimum follow-up of 61 months. We also report that preoperative total spine sagittal malalignment was improved after corrective surgery for cervical kyphosis and was maintained at the latest follow-up in all three cases. The combination of anterior fusion cages and LMS is considered a safe and effective procedure in cases of severe cervical kyphotic deformity. Preoperative total spine sagittal malalignment improved, accompanied by correction of cervical kyphosis, and was maintained at last follow-up in all three cases. PMID:26119893

  9. Timing of hot spot--related volcanism and the breakup of madagascar and India.

    PubMed

    Storey, M; Mahoney, J J; Saunders, A D; Duncan, R A; Kelley, S P; Coffin, M F

    1995-02-10

    Widespread basalts and rhyolites were erupted in Madagascar during the Late Cretaceous. These are considered to be related to the Marion hot spot and the breakup of Madagascar and Greater India. Seventeen argon-40/argon-39 age determinations reveal that volcanic rocks and dikes from the 1500-kilometer-long rifted eastern margin of Madagascar were emplaced rapidly (mean age = 87.6 +/- 0.6 million years ago) and that the entire duration of Cretaceous volcanism on the island was no more than 6 million years. The evidence suggests that the thick lava pile at Volcan de l'Androy in the south of the island marks the focal point of the Marion hot spot at approximately 88 million years ago and that this mantle plume was instrumental in causing continental breakup. PMID:17813912

  10. The Atlas-Centaur 67 incident. [meteorological conditions during lightning caused breakup upon ascent

    NASA Technical Reports Server (NTRS)

    Christian, H. J.; Crouch, K.; Fisher, B.; Mazur, V.; Perala, R. A.

    1988-01-01

    The conditions leading to the breakup of the Atlas-Centaur 67 (AC-67) vehicle launched on March 26, 1987 during a typical winter-time storm are analyzed, and a most probable lightning strike scenario was developed based on inspection of the AC-67 debris, the AC-68 vehicle, and appropriate drawings, electrical diagrams, and photographs. It is shown that, during ascent, the vehicle encountered increasingly larger electric fields and flew through clouds that produced precipitation static on the vehicle, eventually triggering a cloud-to-ground lightning, comprised of at least four return strokes. The resulting lightning current coupled a signal into the wiring which goes to the AC-67 digital computer unit (DCU), effecting a single-word memory alteration and causing the DCU to issue a hardover engine gimbal command. This led to an excessive angle of attack, large dynamic loads, and the breakup of the AC-67.

  11. Small-scale modeling of ice flow perturbations induced by sudden ice shelf breakup

    NASA Astrophysics Data System (ADS)

    Corti, Giacomo; Zeoli, Antonio; Iandelli, Irene

    2014-08-01

    The sudden breakup of ice shelves is expected to result in significant acceleration of inland glaciers, a process related to the removal of the buttressing effect exerted by the ice shelf on the tributary glaciers. In this paper, this process is analyzed by means of scaled analogue experiments reproducing the flow of a valley glacier draining an ice sheet grounded above sea level into an ice shelf, and analyzing the dynamic perturbations resulting from ice shelf disintegration and removal of buttressing effect. Models show a significant increase in glacier velocity close to its outlet following ice shelf breakup, a transient effect that does not significantly propagate upstream towards the ice sheet and rapidly decays with time. Basal lubrication and variations in ice thickness do not significantly influence the process that thus leaves the ice sheet almost unaffected by flow perturbations.

  12. Break-up and Coherent Photoproduction of {eta} Mesons on the Deuteron

    SciTech Connect

    Hoffmann-Rothe, P.; Breuer, M.; Hourany, E.; Rigney, M.; Ajaka, J.; Berrier-Ronsin, G.; Didelez, J.; Rosier, L.; Hey, J.; Anton, G.; Beulertz, W.; Bock, A.; Helbing, K.; Krebeck, M.; Edel, G.v.; Maass, R.; Schumacher, M.; Smend, F.; Blanpied, G.; Preedom, B.; Richie, B.; Saghai, B.; Arends, J.

    1997-06-01

    We present new break-up and coherent data for {eta} meson photoproduction on the deuteron, using a deuterium target and tagged bremsstrahlung photons up to 1GeV. The differential cross sections for the coherent process were measured from threshold to 800MeV. They are much smaller than those previously reported. The break-up channel provides a direct measurement of the neutron to proton differential cross section ratios. At the S{sub 11}(1535) resonance peak, {sigma}{sub n}/{sigma}{sub p}=0.68{plus_minus}0.06 leading to an isoscalar to isovector amplitude ratio of A{sub s}/A{sub {upsilon}}=0.096{plus_minus}0.02 . {copyright} {ital 1997} {ital The American Physical Society}

  13. Numerical assessment of post-prior equivalence for inclusive breakup reactions

    NASA Astrophysics Data System (ADS)

    Lei, Jin; Moro, Antonio M.

    2015-12-01

    We address the problem of the post-prior equivalence in inclusive breakup reactions induced by weakly bound nuclei. The problem is studied within the distorted-wave Born approximation (DWBA) model of Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985), 10.1103/PhysRevC.32.431]. The post and prior formulas obtained in this model are briefly recalled and applied to several breakup reactions induced by deuterons and 6Li projectiles, to test their actual numerical equivalence. The different contributions of the prior-form formula are also discussed. A critical comparison with the prior-form DWBA model of Udagawa and Tamura [Phys. Rev. C 24, 1348 (1981), 10.1103/PhysRevC.24.1348] is also provided.

  14. Total cross section for /p-d breakup below 30 MeV

    NASA Astrophysics Data System (ADS)

    Kievsky, A.; Brune, C. R.; Viviani, M.

    2000-05-01

    The total cross section for /p-d breakup is studied in terms of the elastic /S-matrix through the unitary condition. Calculations using the complex Kohn variational method along with the Pair Correlated Hyperspherical Harmonic basis are presented. The results have been restricted to energies below Ep=30 MeV where Coulomb effects are expected to be sizable and are compared to the existing data. Two different measurements have been found in the literature: 40 years ago, Gibbons and Macklin [Phys. Rev. 114 (1959) 571] and 26 years ago, Carlson et al. [Lett. Nuovo Cimento 8 (1973) 319]. The calculations are found to be in reasonable agreement with these old data, though a discrepancy is observed near the deuteron breakup threshold. Moreover, a detailed analysis of the contributions to the observable from different partial waves has been performed. Unexpectedly, the main contribution for a wide range of energies has been detected in the J=3/2- state.

  15. Parametric study on the fuel film breakup of a cold start PFI engine

    NASA Astrophysics Data System (ADS)

    Wang, Y.-P.; Wilkinson, G. B.; Drallmeier, J. A.

    In order to provide more insight on improving the cold start fuel atomization for reducing unburned hydrocarbon emissions, the liquid fuel film breakup phenomenon in the intake valve/port region was investigated in depth for port-fuel-injected engines. Experiments were conducted using high-speed high-resolution imaging techniques to visualize the liquid film atomization and airflow patterns in an axisymmetric steady flow apparatus. The impact of valve/port seat geometry, surface roughness, and fuel properties on airflow separation and fuel film breakup were determined through a parametric study. CFD simulations were also performed with FLUENT to help understand the airflow behavior inside the intake port and valve gap region and its potential impact on fuel film atomization.

  16. LEBU drag reduction in high Reynolds number boundary layers. [Large Eddy Break-Up

    NASA Technical Reports Server (NTRS)

    Anders, J. B.

    1989-01-01

    Conventional and inverted, outer-layer leading-edge breakup devices (LEBUs) were water tunnel tested on an axisymmetric body over the Re number range from 380,000 to 3.8 million. Test results indicate a sharp degradation of the LEBUs' drag-reduction mechanism with increasing Re number. The most likely result of this degradation is a decoupling of the inner and outer scales at higher Re numbers; due to this decoupling, the breakup of the large structures by outer-layer devices has minimal influence on the near-wall, shear-producing scales. This suggests that smaller devices, closer to the walls, may be required for operation at elevated Re numbers.

  17. Collective Rayleigh-Plateau Instability: A Mimic of Droplet Breakup in High Internal Phase Emulsion.

    PubMed

    Mansard, Vincent; Mecca, Jodi M; Dermody, Dan L; Malotky, David; Tucker, Chris J; Squires, Todd M

    2016-03-22

    Using a microfluidic multi-inlet coflow system, we show the Rayleigh-Plateau instability of adjacent, closely spaced fluid threads to be collective. Although droplet size distributions and breakup frequencies are unaffected by cooperativity when fluid threads are identical, breakup frequencies and wavelengths between mismatched fluid threads become locked due to this collective instability. Locking narrows the size distribution of drops that are produced from dissimilar threads, and thus the polydispersity of the emulsion. These observations motivate a hypothesized two-step mechanism for high internal phase emulsification, wherein coarse emulsion drops are elongated into close-packed fluid threads, which break into smaller droplets via a collective Rayleigh Plateau instability. Our results suggest that these elongated fluid threads break cooperatively, whereupon wavelength-locking reduces the ultimate droplet polydispersity of high-internal phase emulsions, consistent with experimental observations. PMID:26963440

  18. Experimental study of Three-Nucleon Dynamics in the dp breakup reaction

    NASA Astrophysics Data System (ADS)

    Kłos, B.; Ciepał, I.; Khatri, G.; Kistryn, S.; Kozela, A.; Magiera, A.; Parol, W.; Skwira-Chalot, I.; Stephan, E.; Szpik, K.

    2016-03-01

    An experiment to investigate the 1H(d,pp)n breakup reaction using a deuteron beam of 340, 380 and 400 MeV and the WASA detector has been performed at the Cooler Synchrotron COSY-Jülich. The main goal was a detailed study of various aspects of fewnucleon dynamics like the three nucleon force (3NF), the long-range Coulomb interaction or relativistic effects in the medium energy region. The relativistic effects and their interplay with 3NF become more important with increasing available energy in the three nucleon system. The almost 4π geometry of the WASA detector provides an unique possibility to study various aspects of dynamics. The studies of the 3N system dynamics in the breakup reaction with BINA detector are continued in the Cyclotron Center Bronowice.

  19. Thermonuclear breakup reactions of light nuclei. I - Processes and effects. [in astrophysic plasmas

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal; Gould, Robert J.

    1989-01-01

    Temperature and density conditions are considered for the occurrence of breakup reactions of light nuclei in astrophysical plasmas. The proton-induced endothermic process is shown to be the principal mechanism for nuclear breakdown in a plasma. The phenomenon occurs at a temperature of about 1 MeV, which is a fraction of the typical binding energy per nucleon in nuclei. The temperature for breakup of He-4 is about twice as large, because of the higher binding energy. Depending on the temperature attained in the plasma, the initial concentration of elements heavier than hydrogen can be depleted. However, if it attains a temperature of about 1 MeV, breaking up the metals (C, N, O, Ne, Mg) but not He-4, an increase in the He-4 abundance by as much as 10 percent can result, since these elements essentially break down to alpha particles.

  20. Theoretical study of the elastic breakup of weakly bound nuclei at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Otomar, D. R.; Gomes, P. R. S.; Lubian, J.; Canto, L. F.; Hussein, M. S.

    2015-12-01

    We have performed continuum discretized coupled channel (CDCC) calculations for collisions of 7Li projectiles on 59Co,144Sm, and 208Pb targets at near-barrier energies, to assess the importance of the Coulomb and the nuclear couplings in the breakup of 7Li, as well as the Coulomb-nuclear interference. We have also investigated scaling laws, expressing the dependence of the cross sections on the charge and the mass of the target. This work is complementary to that previously reported by us on the breakup of 6Li. Here we explore the similarities and differences between the results for the two lithium isotopes. The relevance of the Coulomb dipole and quadrupole strengths at low energy for the two-cluster projectile is investigated in detail.