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Sample records for bulk viscosity drive

  1. Exploring a matter-dominated model with bulk viscosity to drive the accelerated expansion of the Universe

    SciTech Connect

    Avelino, Arturo; Nucamendi, Ulises E-mail: ulises@ifm.umich.mx

    2010-08-01

    We explore the viability of a bulk viscous matter-dominated Universe to explain the present accelerated expansion of the Universe. The model is composed by a pressureless fluid with bulk viscosity of the form ζ = ζ{sub 0}+ζ{sub 1}H where ζ{sub 0} and ζ{sub 1} are constants and H is the Hubble parameter. The pressureless fluid characterizes both the baryon and dark matter components. We study the behavior of the Universe according to this model analyzing the scale factor as well as some curvature scalars and the matter density. On the other hand, we compute the best estimated values of ζ{sub 0} and ζ{sub 1} using the type Ia Supernovae (SNe Ia) probe. We find that from all the possible scenarios for the Universe, the preferred one by the best estimated values of (ζ{sub 0},ζ{sub 1}) is that of an expanding Universe beginning with a Big-Bang, followed by a decelerated expansion at early times, and with a smooth transition in recent times to an accelerated expansion epoch that is going to continue forever. The predicted age of the Universe is a little smaller than the mean value of the observational constraint coming from the oldest globular clusters but it is still inside of the confidence interval of this constraint. A drawback of the model is the violation of the local second law of thermodynamics in redshifts z∼>1. However, when we assume ζ{sub 1} = 0, the simple model ζ = ζ{sub 0} evaluated at the best estimated value for ζ{sub 0} satisfies the local second law of thermodynamics, the age of the Universe is in perfect agreement with the constraint of globular clusters, and it also has a Big-Bang, followed by a decelerated expansion with the smooth transition to an accelerated expansion epoch in late times, that is going to continue forever.

  2. Can a matter-dominated model with constant bulk viscosity drive the accelerated expansion of the universe?

    SciTech Connect

    Avelino, Arturo; Nucamendi, Ulises E-mail: ulises@ifm.umich.mx

    2009-04-15

    We test a cosmological model which the only component is a pressureless fluid with a constant bulk viscosity as an explanation for the present accelerated expansion of the universe. We classify all the possible scenarios for the universe predicted by the model according to their past, present and future evolution and we test its viability performing a Bayesian statistical analysis using the SCP ''Union'' data set (307 SNe Ia), imposing the second law of thermodynamics on the dimensionless constant bulk viscous coefficient {zeta}-tilde and comparing the predicted age of the universe by the model with the constraints coming from the oldest globular clusters. The best estimated values found for {zeta}-tilde and the Hubble constant H{sub 0} are: {zeta}-tilde = 1.922{+-}0.089 and H{sub 0} = 69.62{+-}0.59 (km/s)Mpc{sup -1} with a {chi}{sup 2}{sub min} = 314 ({chi}{sup 2}{sub d.o.f} = 1.031). The age of the universe is found to be 14.95{+-}0.42 Gyr. We see that the estimated value of H{sub 0} as well as of {chi}{sup 2}{sub d.o.f} are very similar to those obtained from {Lambda}CDM model using the same SNe Ia data set. The estimated age of the universe is in agreement with the constraints coming from the oldest globular clusters. Moreover, the estimated value of {zeta}-tilde is positive in agreement with the second law of thermodynamics (SLT). On the other hand, we perform different forms of marginalization over the parameter H{sub 0} in order to study the sensibility of the results to the way how H{sub 0} is marginalized. We found that it is almost negligible the dependence between the best estimated values of the free parameters of this model and the way how H{sub 0} is marginalized in the present work. Therefore, this simple model might be a viable candidate to explain the present acceleration in the expansion of the universe.

  3. Anomalous - viscosity current drive

    DOEpatents

    Stix, Thomas H.; Ono, Masayuki

    1988-01-01

    An apparatus and method for maintaining a steady-state current in a toroidal magnetically confined plasma. An electric current is generated in an edge region at or near the outermost good magnetic surface of the toroidal plasma. The edge current is generated in a direction parallel to the flow of current in the main plasma and such that its current density is greater than the average density of the main plasma current. The current flow in the edge region is maintained in a direction parallel to the main current for a period of one or two of its characteristic decay times. Current from the edge region will penetrate radially into the plasma and augment the main plasma current through the mechanism of anomalous viscosity. In another aspect of the invention, current flow driven between a cathode and an anode is used to establish a start-up plasma current. The plasma-current channel is magnetically detached from the electrodes, leaving a plasma magnetically insulated from contact with any material obstructions including the cathode and anode.

  4. Anomalous-viscosity current drive

    DOEpatents

    Stix, T.H.; Ono, M.

    1986-04-25

    The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

  5. Bulk viscosity of a pion gas

    NASA Astrophysics Data System (ADS)

    Lu, Egang; Moore, Guy D.

    2011-04-01

    We compute the bulk viscosity of a gas of pions at temperatures below the QCD crossover temperature, for the physical value of mπ, to lowest order in chiral perturbation theory. Bulk viscosity is controlled by number-changing processes which become exponentially slow at low temperatures when the pions become exponentially dilute, leading to an exponentially large bulk viscosity ζ~(F08/mπ5)exp(2mπ/T), where F0≃93MeV is the pion decay constant.

  6. Bulk viscosity of multiparticle collision dynamics fluids.

    PubMed

    Theers, Mario; Winkler, Roland G

    2015-03-01

    We determine the viscosity parameters of the multiparticle collision dynamics (MPC) approach, a particle-based mesoscale hydrodynamic simulation method for fluids. We perform analytical calculations and verify our results by simulations. The stochastic rotation dynamics and the Andersen thermostat variant of MPC are considered, both with and without angular momentum conservation. As an important result, we find a nonzero bulk viscosity for every MPC version. The explicit calculation shows that the bulk viscosity is determined solely by the collisional interactions of MPC. PMID:25871248

  7. Thermal relics in cosmology with bulk viscosity

    NASA Astrophysics Data System (ADS)

    Iorio, A.; Lambiase, G.

    2015-03-01

    In this paper we discuss some consequences of cosmological models in which the primordial cosmic matter is described by a relativistic imperfect fluid. The latter takes into account the dissipative effects (bulk viscosity) arising from different cooling rates of the fluid components in the expanding Universe. We discuss, in particular, the effects of the bulk viscosity on Big Bang Nucleosynthesis and on the thermal relic abundance of particles, looking at recent results of PAMELA experiment. The latter has determined an anomalous excess of positron events, which cannot be explained by conventional cosmology and particle physics.

  8. Cosmological two-fluid bulk viscosity

    NASA Astrophysics Data System (ADS)

    van den Horn, L. J.; Salvati, G. A. Q.

    2016-04-01

    A simple two-fluid model of cosmological bulk viscosity, in which small deviations from thermal equilibrium account for the viscous bulk pressure, is substantiated by kinetic theory. Some peculiar issues regarding its relation to the radiative fluid model are discussed. The microphysical picture underlying the viscous dissipation is made precise. We also consider a reactive `cross' viscosity associated with deviations from detailed balance, which includes the so-called creation pressure of the cosmological fluid. For collisional interactions between the fluid components, the reactive viscous pressure is not an independent mechanism for entropy production. Entropy from cross effects may be generated through an effective isentropic particle source. In both instances new results are obtained for the reactive viscosity, and applied to a representative case of non-equilibrium decay.

  9. New approach to cosmological bulk viscosity

    NASA Astrophysics Data System (ADS)

    Disconzi, Marcelo M.; Kephart, Thomas W.; Scherrer, Robert J.

    2015-02-01

    We examine the cosmological consequences of an alternative to the standard expression for bulk viscosity, one which was proposed to avoid the propagation of superluminal signals without the necessity of extending the space of variables of the theory. The Friedmann equation is derived for this case, along with an expression for the effective pressure. We find solutions for the evolution of the density of a viscous component, which differs markedly from the case of conventional Eckart theory; our model evolves toward late-time phantomlike behavior with a future singularity. Entropy production is addressed, and some similarities and differences to approaches based on the Mueller-Israel-Stewart theory are discussed.

  10. Eling-Oz formula for the holographic bulk viscosity

    NASA Astrophysics Data System (ADS)

    Buchel, Alex

    2011-05-01

    Recently Eling and Oz [1] proposed a simple formula for the bulk viscosity of holographic plasma. They argued that the formula is valid in the high temperature (near-conformal) regime, but is expected to break down at low temperatures. We point out that the formula is in perfect agreement with the previous computations of the bulk viscosity of the cascading plasma [2, 3], as well as with the previous computations of the bulk viscosity of {N} = {2^*} plasma [4, 5]. In the latter case it correctly reproduces the critical behaviour of the bulk viscosity in the vicinity of the critical point with the vanishing speed of sound.

  11. Bulk viscosity effect on freely decaying compressible homogeneous isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Pan, Shaowu; Johnsen, Eric

    2015-11-01

    Despite growing interests in compressible turbulence, the effect of bulk viscosity has been long ignored. For certain gases, the bulk viscosity may be 1000 times greater than the shear viscosity and thus modify energy transfer and dissipation mechanisms. In this study, we use direct numerical simulations to investigate the role of bulk viscosity on decaying isotropic compressible turbulence. Our results show that bulk viscosity exhibits a negligible decrease on enstrophy, but moderate and significant increases on the turbulent kinetic energy and Taylor-scale Reynolds number, respectively. A Helmholtz decomposition of the velocity field indicates that the bulk viscosity has a negligible effect on the solenoidal part, but exhibits a cross-scale effect on the dilatational component.

  12. Bulk viscosity of anisotropically expanding hot QCD plasma

    SciTech Connect

    Chandra, Vinod

    2011-11-01

    The bulk viscosity, {zeta} and its ratio with the shear viscosity, {zeta}/{eta} have been studied in an anisotropically expanding pure glue plasma in the presence of turbulent color fields. It has been shown that the anisotropy in the momentum distribution function of gluons, which has been determined from a linearized transport equation eventually leads to the bulk viscosity. For the isotropic (equilibrium) state, a recently proposed quasiparticle model of pure SU(3) lattice QCD equation of state has been employed where the interactions are encoded in the effective fugacity. It has been argued that the interactions present in the equation of state, significantly contribute to the bulk viscosity. Its ratio with the shear viscosity is significant even at 1.5T{sub c}. Thus, one needs to take in account the effects of the bulk viscosity while studying the hydrodynamic expansion of quark-gluon plasma in the Relativistic Heavy Ion Collider and the Large Hadron Collider.

  13. Theoretical evaluation of bulk viscosity: Expression for relaxation time

    NASA Astrophysics Data System (ADS)

    Hossein Mohammad Zaheri, Ali; Srivastava, Sunita; Tankeshwar, K.

    2007-10-01

    A theoretical calculation of bulk viscosity has been carried out by deriving an expression for the relaxation time which appears in the formula for bulk viscosity derived by Okumura and Yonezawa. The expression involved a pair distribution function and interaction potential. Numerical results have been obtained over a wide range of densities and temperatures for Lennard-Jones fluids. It is found that our results provide a good description of bulk viscosity as has been judged by comparing the results with nonequilibrium molecular dynamics results. In addition, our results demonstrate the importance of the multiparticle correlation function.

  14. Bulk and shear viscosities for the Gribov-Zwanziger plasma

    NASA Astrophysics Data System (ADS)

    Florkowski, Wojciech

    2016-07-01

    The concept of the Gribov-Zwanziger plasma is introduced and used to calculate the bulk and shear viscosities of the system of gluons. The kinetic coeffcients are obtained in two different ways which are shown to yield equivalent results.

  15. Bulk viscosity of strange quark matter: Urca versus nonleptonic processes

    SciTech Connect

    Sa'd, Basil A.; Shovkovy, Igor A.; Rischke, Dirk H.

    2007-06-15

    A general formalism for calculating the bulk viscosity of strange quark matter is developed. Contrary to the common belief that the nonleptonic processes alone give the dominant contribution to the bulk viscosity, the inclusion of the Urca processes is shown to play an important role at intermediate densities when the characteristic r-mode oscillation frequencies are not too high. The interplay of nonleptonic and Urca processes is analyzed in detail.

  16. Fluctuations in horizon-fluid lead to negative bulk viscosity

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Swastik; Shankaranarayanan, S.

    2016-03-01

    Einstein equations projected on to a black-hole horizon give rise to Navier-Stokes equations. Horizon-fluids typically possess unusual features like negative bulk viscosity, and it is not clear whether a statistical-mechanical description exists for such fluids. In this work, we provide an explicit derivation of the Bulk viscosity of the horizon-fluid based on the theory of fluctuations à la Kubo. The main advantage of our approach is that our analysis remains for the most part independent of the details of the underlying microscopic theory and hence the conclusions reached here are model independent. We show that the coefficient of bulk viscosity for the horizon-fluid matches exactly with the value found from the equations of motion for the horizon-fluid.

  17. Bulk viscosity coefficients due to phonons in superfluid neutron stars

    SciTech Connect

    Manuel, Cristina; Tolos, Laura; Tarrús, Jaume E-mail: tarrus@ecm.ub.edu

    2013-07-01

    We calculate the three bulk viscosity coefficients as arising from the collisions among phonons in superfluid neutron stars. We use effective field theory techniques to extract the allowed phonon collisional processes, written as a function of the equation of state of the system. The solution of the dynamical evolution of the phonon number density allows us to calculate the bulk viscosity coefficients as function of the phonon collisional rate and the phonon dispersion law, which depends on the neutron pairing gap. Our method of computation is rather general, and could be used for different superfluid systems, provided they share the same underlying symmetries. We find that the behavior with temperature of the bulk viscosity coefficients is dominated by the contributions coming from the collinear regime of the 2↔3 phonon processes. For typical star radial pulsation frequencies of ω ∼ 10{sup 4}s{sup −1}, we obtain that the bulk viscosity coefficients at densities n∼>4n{sub 0} are within 10% from its static value for T∼<10{sup 9} K and for the case of strong neutron superfluidity in the core with a maximum value of the {sup 3}P{sub 2} gap above 1 MeV, while, otherwise, the static solution is not a valid approximation to the bulk viscosity coefficients. Compared to previous results from Urca and modified Urca reactions, we conclude that at T ∼ 10{sup 9}K phonon collisions give the leading contribution to the bulk viscosities in the core of the neutron stars, except for n ∼ 2n{sub 0} when the opening of the Urca processes takes place.

  18. Nonlinear bulk viscosity in FRW cosmology: a phase space analysis.

    NASA Astrophysics Data System (ADS)

    Acquaviva, G.; Beesham, A.

    2015-11-01

    We consider a Friedmann-Robertson-Walker spacetime filled with both viscous radiation and nonviscous dust. The former has a bulk viscosity that is proportional to an arbitrary power of the energy density, i.e. \\zeta \\propto {ρ }{{v}}ν , and viscous pressure satisfying a nonlinear evolution equation. The analysis is carried out in the context of dynamical systems and the properties of solutions corresponding to the fixed points are discussed. For some ranges of the relevant parameter ν we find that the trajectories in the phase space evolve from a FRW singularity towards an asymptotic de Sitter attractor, confirming and extending previous analysis in the literature.

  19. Late decaying dark matter, bulk viscosity, and the cosmic acceleration

    SciTech Connect

    Mathews, G. J.; Kolda, C.; Lan, N. Q.

    2008-08-15

    We discuss a cosmology in which cold dark matter begins to decay into relativistic particles at a recent epoch (z<1). We show that the large entropy production and associated bulk viscosity from such decays leads to an accelerating cosmology as required by observations. We investigate the effects of decaying cold dark matter in a {lambda}=0, flat, initially matter dominated cosmology. We show that this model satisfies the cosmological constraint from the redshift-distance relation for type Ia supernovae. The age in such models is also consistent with the constraints from the oldest stars and globular clusters. Possible candidates for this late decaying dark matter are suggested along with additional observational tests of this cosmological paradigm.

  20. Probing the bulk viscosity of particles using aerosol optical tweezers

    NASA Astrophysics Data System (ADS)

    Power, Rory; Bones, David L.; Reid, Jonathan P.

    2012-10-01

    Holographic aerosol optical tweezers can be used to trap arrays of aerosol particles allowing detailed studies of particle properties and processes at the single particle level. Recent observations have suggested that secondary organic aerosol may exist as ultra-viscous liquids or glassy states at low relative humidity, potentially a significant factor in influencing their role in the atmosphere and their activation to form cloud droplets. A decrease in relative humidity surrounding a particle leads to an increased concentration of solute in the droplet as the droplet returns to equilibrium and, thus, an increase in the bulk viscosity. We demonstrate that the timescales for condensation and evaporation processes correlate with particle viscosity, showing significant inhibition in mass transfer kinetics using ternary sucrose/sodium chloride/water droplets as a proxy to atmospheric multi-component aerosol. We go on to study the fundamental process of aerosol coagulation in aerosol particle arrays, observing the relaxation of non-spherical composite particles formed on coalescence. We demonstrate the use of bright-field imaging and elastic light scattering to make measurements of the timescale for the process of binary coalescence contrasting the rheological properties of aqueous sucrose and sodium chloride aerosol over a range of relative humidities.

  1. Acoustic Experiment to Measure the Bulk Viscosity of Near-Critical Xenon in Microgravity

    NASA Technical Reports Server (NTRS)

    Gillis, K. A.; Shinder, I.; Moldover, M. R.; Zimmerli, G. A.

    2002-01-01

    We plan a rigorous test of the theory of dynamic scaling by accurately measuring the bulk viscosity of xenon in microgravity 50 times closer to the critical temperature T(sub c) than previous experiments. The bulk viscosity zeta (or "second viscosity" or "dilational viscosity") will be determined by measuring the attenuation length of sound alpha lambda and also measuring the frequency-dependence of the speed of sound. For these measurements, we developed a unique Helmholtz resonator and specialized electro-acoustic transducers. We describe the resonator, the transducers, their performance on Earth, and their expected performance in microgravity.

  2. Bulk and shear viscosities of partially molten rocks: Experimental approach using analogue material

    NASA Astrophysics Data System (ADS)

    Suzuki, A. M.; Watanabe, S.; Takei, Y.

    2012-12-01

    Deformation of partially molten rock has two types: shear deformation and compaction/decompaction. The former is controlled by shear viscosity, and the latter by bulk viscosity. While shear viscosity has been measured extensively, relatively few experimental studies have investigated bulk viscosity (Renner et al., 2003). Bulk viscosity and its ratio to shear viscosity, ξ/η, play an important role in melt segregation dynamics (Katz, 2008). Most numerical studies has used the theoretically predicted value of ξ/η~φ-1, where φ is the melt fraction. However, Takei and Holtzman (2009) theoretically obtained a value of ξ/η=1.7 by taking into account a diffusion creep mechanism. The discrepancy between two models is significant at small φ. To discuss the validity of these models based on the experimental data, it is highly important to measure both bulk and shear viscosities by using identical samples. In this study, we measured experimentally bulk and shear viscosities as functions of melt fraction using a partially molten rock analogue. Samples were polycrystalline aggregates of borneol-diphenylamine binary with eutectic temperature of 316K, which has a quite similar equilibrium microstructure to olivine + basalt system (Takei, 2000). Initial melt fraction can be controlled precisely by the amount of diphenylamine because of its simple eutectic reaction. Before deformation experiments, samples were annealed at 320K for ~100 hours in a sealed capsule to make those grain size large enough (~30μm), resulted in negligible grain growth during the successive deformation tests at the same temperature. To measure the bulk and shear viscosities, we carried out two separate experiments. For bulk viscosity, we performed compaction experiments in which melt was squeezed from the partially molten sample. A cylindrical sample contacted with porous metals at the top and bottom ends was compacted uniaxially in a rigid sleeve (ɛzz ≠ 0, ɛxx = ɛyy = 0). Melt can flow out

  3. Bulk viscosity of spin-one color superconductors with two quark flavors

    SciTech Connect

    Sa'd, Basil A.; Shovkovy, Igor A.; Rischke, Dirk H.

    2007-03-15

    We consider the contribution of the Urca-type processes to the bulk viscosity of several spin-one color-superconducting phases of dense two-flavor quark matter. In the so-called transverse phases which are suggested to be energetically favorable at asymptotic densities, the presence of ungapped quasiparticle modes prevents that spin-one color superconductivity has a large effect on the bulk viscosity. When all modes are gapped, as for one particular color-spin-locked phase, the effect on the viscosity can be quite large, which may have important phenomenological implications.

  4. Progress on Acoustic Measurements of the Bulk Viscosity of Near-Critical Xenon (BVX)

    NASA Technical Reports Server (NTRS)

    Gillis, Keith A.; Shinder, Iosif I.; Moldover, Michael R.; Zimmerli, Gregory A.

    2004-01-01

    We plan to determine the bulk viscosity of xenon 10 times closer [in reduced temperature tau = (T-Tc)/Tc] to its liquid-vapor critical point than ever before. (Tc is the critical temperature.) To do so, we must measure the dispersion and attenuation of sound at frequencies 1/100 of those used previously. In general, sound attenuation has contributions from the bulk viscosity acting throughout the volume of the xenon as well as contributions from the thermal conductivity and the shear viscosity acting within thin thermoacoustic boundary layers at the interface between the xenon and the solid walls of the resonator. Thus, we can determine the bulk viscosity only when the boundary layer attenuation is small and well understood. We present a comparison of calculations and measurements of sound attenuation in the acoustic boundary layer of xenon near its liquid-vapor critical point.

  5. Effect of Large Bulk Viscosity on Two-Dimensional Transonic Flow

    NASA Astrophysics Data System (ADS)

    Cramer, Mark

    2012-11-01

    We examine steady two-dimensional transonic flows over a thin airfoil or turbine blade. The wing Reynolds number is taken to be large and the fluid is described by the classical Navier-Stokes equations. The bulk viscosity is taken to be large compared to the shear viscosity. We use the Method of Matched Asymptotic Expansions to give the conditions under which the effects of large bulk viscosity are no longer negligible. We show that longitudinal viscous effects must be considered at lowest order when the ratio of bulk to shear viscosity is on the order of the product of the conventional Reynolds number times the two-thirds power of the non-dimensional airfoil thickness. Under these conditions the flow is shown to be frictional, irrotational, and governed by the viscous form of the transonic small disturbance equation. This work was supported by NSF Grant CBET-0625015.

  6. Effect of Viscosity on the Microformability of Bulk Amorphous Alloy in Supercooled Liquid Region

    SciTech Connect

    Cheng Ming; Zhang Shihong; Wang Ruixue

    2010-06-15

    Previously published results have shown that viscosity greatly influences on the deformation behavior of the bulk amorphous alloy in supercooled liquid region during microforming process. And viscosity is proved to be a component of the evaluation index which indicating microformability. Based on the fluid flow theory and assumptions, bulk amorphous alloy can be regarded as the viscous materials with a certain viscosity. It is helpful to understand how the viscosity plays an important role in viscous materials with various viscosities by numerical simulation on the process. Analysis is carried out by linear state equation in FEM with other three materials, water, lubricant oil and polymer melt, whose viscosities are different obviously. The depths of the materials flow into the U-shaped groove during the microimprinting process are compared in this paper. The result shows that the deformation is quite different when surface tension effect is not considered in the case. With the lowest viscosity, water can reach the bottom of micro groove in a very short time. Lubricant oil and polymer melt slower than it. Moreover bulk amorphous alloys in supercooled liquid state just flow into the groove slightly. Among the alloys of different systems including Pd-, Mg- and Zr-based alloy, Pd-based alloy ranks largest in the depth. Mg-based alloy is the second. And Zr-based alloy is the third. Further more the rank order of the viscosities of the alloys is Pd-, Mg- and Zr-based. It agrees well with the results of calculation. Therefore viscosity plays an important role in the microforming of the bulk amorphous alloy in the supercooled liquid state.

  7. Bulk Viscosity and Conformal Symmetry Breaking in the Dilute Fermi Gas near Unitarity

    NASA Astrophysics Data System (ADS)

    Dusling, Kevin; Schäfer, Thomas

    2013-09-01

    The dilute Fermi gas at unitarity is scale invariant and its bulk viscosity vanishes. We compute, in the high temperature limit, the leading contribution to the bulk viscosity when the scattering length is not infinite. A measure of scale breaking is provided by the ratio (P-2/3E)/P, where P is the pressure and E is the energy density. At high temperature this ratio scales as zλ/a, where z is the fugacity, λ is the thermal wavelength, and a is the scattering length. We show that the bulk viscosity ζ scales as the second power of this parameter, ζ˜(zλ/a)2λ-3.

  8. Computing bulk and shear viscosities from simulations of fluids with dissipative and stochastic interactions

    NASA Astrophysics Data System (ADS)

    Jung, Gerhard; Schmid, Friederike

    2016-05-01

    Exact values for bulk and shear viscosity are important to characterize a fluid, and they are a necessary input for a continuum description. Here we present two novel methods to compute bulk viscosities by non-equilibrium molecular dynamics simulations of steady-state systems with periodic boundary conditions — one based on frequent particle displacements and one based on the application of external bulk forces with an inhomogeneous force profile. In equilibrium simulations, viscosities can be determined from the stress tensor fluctuations via Green-Kubo relations; however, the correct incorporation of random and dissipative forces is not obvious. We discuss different expressions proposed in the literature and test them at the example of a dissipative particle dynamics fluid.

  9. Computing bulk and shear viscosities from simulations of fluids with dissipative and stochastic interactions.

    PubMed

    Jung, Gerhard; Schmid, Friederike

    2016-05-28

    Exact values for bulk and shear viscosity are important to characterize a fluid, and they are a necessary input for a continuum description. Here we present two novel methods to compute bulk viscosities by non-equilibrium molecular dynamics simulations of steady-state systems with periodic boundary conditions - one based on frequent particle displacements and one based on the application of external bulk forces with an inhomogeneous force profile. In equilibrium simulations, viscosities can be determined from the stress tensor fluctuations via Green-Kubo relations; however, the correct incorporation of random and dissipative forces is not obvious. We discuss different expressions proposed in the literature and test them at the example of a dissipative particle dynamics fluid. PMID:27250276

  10. Effects of a transient bulk viscosity on the evolution of FRW universes with decaying vacuum energy.

    NASA Astrophysics Data System (ADS)

    Abdussattar; Vishwakarma, R. G.

    1995-10-01

    The effects of incorporating a transient bulk viscosity, which is operative during an instantaneous phase transition, into the FRW universes with a vacuum energy decaying according to Chen-Wu ansatz are studied. The presence of vacuum is instrumental in avoiding the initial singularity and liberalizes the choice of initial conditions, thereby giving rise to different possible scenarios. It is found that the Hubble parameter and the energy density suffer a discontinuity in the presence of the transient bulk viscosity, which being the source of such a discontinuity, leads to viscous heating and/or particle production and influences the subsequent evolution.

  11. Shear viscosity, bulk viscosity, and relaxation times of causal dissipative relativistic fluid-dynamics at finite temperature and chemical potential

    NASA Astrophysics Data System (ADS)

    Huang, Xu-Guang; Koide, Tomoi

    2012-09-01

    The microscopic formulas for the shear viscosity η, the bulk viscosity ζ, and the corresponding relaxation times τπ and τΠ of causal dissipative relativistic fluid-dynamics are obtained at finite temperature and chemical potential by using the projection operator method. The non-triviality of the finite chemical potential calculation is attributed to the arbitrariness of the operator definition for the bulk viscous pressure. We show that, when the operator definition for the bulk viscous pressure Π is appropriately chosen, the leading-order result of the ratio, ζ over τΠ, coincides with the same ratio obtained at vanishing chemical potential. We further discuss the physical meaning of the time-convolutionless (TCL) approximation to the memory function, which is adopted to derive the main formulas. We show that the TCL approximation violates the time reversal symmetry appropriately and leads results consistent with the quantum master equation obtained by van Hove. Furthermore, this approximation can reproduce an exact relation for transport coefficients obtained by using the f-sum rule derived by Kadanoff and Martin. Our approach can reproduce also the result in Baier et al. (2008) [8] by taking into account the next-order correction to the TCL approximation, although this correction causes several problems.

  12. Torque Transient of Magnetically Drive Flow for Viscosity Measurement

    NASA Technical Reports Server (NTRS)

    Ban, Heng; Li, Chao; Su, Ching-Hua; Lin, Bochuan; Scripa, Rosalia N.; Lehoczky, Sandor L.

    2004-01-01

    Viscosity is a good indicator of structural changes for complex liquids, such as semiconductor melts with chain or ring structures. This paper discusses the theoretical and experimental results of the transient torque technique for non-intrusive viscosity measurement. Such a technique is essential for the high temperature viscosity measurement of high pressure and toxic semiconductor melts. In this paper, our previous work on oscillating cup technique was expanded to the transient process of a magnetically driven melt flow in a damped oscillation system. Based on the analytical solution for the fluid flow and cup oscillation, a semi-empirical model was established to extract the fluid viscosity. The analytical and experimental results indicated that such a technique has the advantage of short measurement time and straight forward data analysis procedures

  13. Bulk viscosity of quark-gluon matter in a magnetic field

    SciTech Connect

    Agasian, N. O.

    2013-11-15

    On the basis of low-energy QCD theorems, the bulk viscosity {zeta}(T, Micro-Sign , H) is expressed in terms of basic thermodynamic quantities that characterizes quark-gluon matter at finite temperature and a finite baryon density in a magnetic field. Various limiting cases are considered.

  14. Bulk viscosities of a cold relativistic superfluid: Color-flavor locked quark matter

    SciTech Connect

    Mannarelli, Massimo; Manuel, Cristina

    2010-02-15

    We consider the phonon contribution to the bulk viscosities {zeta}{sub 1}, {zeta}{sub 2} and {zeta}{sub 3} of a cold relativistic superfluid. We assume the low temperature T regime and that the transport properties of the system are dominated by the phonons. We use kinetic theory in the relaxation time approximation and the low energy effective field theory of the corresponding system. The parametric dependence of the bulk viscosity coefficients is fixed once the equation of state is specified, and the phonon dispersion law to cubic order in momentum is known. We first present a general discussion, valid for any superfluid, then we focus on the color-flavor locked superfluid because all the parameters needed in the analysis can be computed in the high density limit of QCD, and also because of the possible astrophysical applications. For the three independent bulk viscosity coefficients we find that they scale with the temperature as {zeta}{sub i{approx}}1/T, and that in the conformal limit only the third coefficient {zeta}{sub 3} is nonzero.

  15. Effect of bulk viscosity in low density, hypersonic blunt body flows

    SciTech Connect

    Rutledge, W.H. ); Hoffmann, K.A. )

    1991-01-01

    A computational fluids dynamics scheme is presented to solve the unsteady Thin-Layer Navier-Stokes (TLNS) equations over a blunt body at high altitude, high Mach number atmospheric reentry flow conditions. This continuum approach is directed to low density hypersonic flows by accounting for non-zero bulk viscosity effects in near frozen flow conditions. The TLNS equations are solved over an axisymmetric body at zero incidence relative to the free stream. The time dependent axisymmetric governing equations are transformed into a computational plane, then cast into weak conservative form and solved using a first-order fully implicit scheme in time with second-order flux vector splitting for spatial derivatives. The physical domain is defined over representative sphere and sphere/cone geometries using a body-fitted clustered algebraic grid within a fixed domain (i.e., shock capturing). At the present time, nonequilibrium thermo-chemistry effects are not modeled. Catalytic wall, ionization and radiation effects are also excluded from the current analysis. However, the significant difference from previous studies is the inclusion of the capability to model non-zero bulk viscosity effects. The importance of bulk viscosity is reviewed and blunt body flow field solutions are presented to illustrate the potential contribution of this phenomena at high altitude hypersonic conditions. The current technique is compared with experimental data and other approximate continuum solutions. A variety of test cases are also presented for a wide range of free stream Mach conditions. 18 refs., 42 figs.

  16. Anisotropic hydrodynamics, bulk viscosities, and r-modes of strange quark stars with strong magnetic fields

    SciTech Connect

    Huang Xuguang; Huang Mei; Rischke, Dirk H.; Sedrakian, Armen

    2010-02-15

    In strong magnetic fields the transport coefficients of strange quark matter become anisotropic. We determine the general form of the complete set of transport coefficients in the presence of a strong magnetic field. By using a local linear response method, we calculate explicitly the bulk viscosities {zeta}{sub perpendicular} and {zeta}{sub ||} transverse and parallel to the B field, respectively, which arise due to the nonleptonic weak processes u+s{r_reversible}u+d. We find that for magnetic fields B<10{sup 17} G, the dependence of {zeta}{sub perpendicular} and {zeta}{sub ||} on the field is weak, and they can be approximated by the bulk viscosity for the zero magnetic field. For fields B>10{sup 18} G, the dependence of both {zeta}{sub perpendicular} and {zeta}{sub ||} on the field is strong, and they exhibit de Haas-van Alphen-type oscillations. With increasing magnetic field, the amplitude of these oscillations increases, which eventually leads to negative {zeta}{sub perpendicular} in some regions of parameter space. We show that the change of sign of {zeta}{sub perpendicular} signals a hydrodynamic instability. As an application, we discuss the effects of the new bulk viscosities on the r-mode instability in rotating strange quark stars. We find that the instability region in strange quark stars is affected when the magnetic fields exceed the value B=10{sup 17} G. For fields which are larger by an order of magnitude, the instability region is significantly enlarged, making magnetized strange stars more susceptible to r-mode instability than their unmagnetized counterparts.

  17. Thermodynamics and Bulk Viscosity of Approximate Black Hole Duals to Finite Temperature Quantum Chromodynamics

    SciTech Connect

    Gubser, Steven S.; Nellore, Abhinav; Pufu, Silviu S.; Rocha, Fabio D.

    2008-09-26

    We consider classes of translationally invariant black hole solutions whose equations of state closely resemble that of QCD at zero chemical potential. We use these backgrounds to compute the ratio {zeta}/s of bulk viscosity to entropy density. For a class of black holes that exhibits a first-order transition, we observe a sharp rise in {zeta}/s near T{sub c}. For constructions that exhibit a smooth crossover, like QCD does, the rise in {zeta}/s is more modest. We conjecture that divergences in {zeta}/s for black hole horizons are related to extrema of the entropy density as a function of temperature.

  18. Bianchi type-VIh string cloud cosmological models with bulk viscosity

    NASA Astrophysics Data System (ADS)

    Tripathy, Sunil K.; Behera, Dipanjali

    2010-11-01

    String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VIh metric in the frame work of general relativity. The field equations are solved for massive string cloud in presence of bulk viscosity. A general linear equation of state of the cosmic string tension density with the proper energy density of the universe is considered. The physical and kinematical properties of the models have been discussed in detail and the limits of the anisotropic parameter responsible for different phases of the universe are explored.

  19. Bulk and shear viscosities of the two-dimensional electron liquid in a doped graphene sheet

    NASA Astrophysics Data System (ADS)

    Principi, Alessandro; Vignale, Giovanni; Carrega, Matteo; Polini, Marco

    2016-03-01

    Hydrodynamic flow occurs in an electron liquid when the mean free path for electron-electron collisions is the shortest length scale in the problem. In this regime, transport is described by the Navier-Stokes equation, which contains two fundamental parameters, the bulk and shear viscosities. In this paper, we present extensive results for these transport coefficients in the case of the two-dimensional massless Dirac fermion liquid in a doped graphene sheet. Our approach relies on microscopic calculations of the viscosities up to second order in the strength of electron-electron interactions and in the high-frequency limit, where perturbation theory is applicable. We then use simple interpolation formulas that allow to reach the low-frequency hydrodynamic regime where perturbation theory is no longer directly applicable. The key ingredient for the interpolation formulas is the "viscosity transport time" τv, which we calculate in this paper. The transverse nature of the excitations contributing to τv leads to the suppression of scattering events with small momentum transfer, which are inherently longitudinal. Therefore, contrary to the quasiparticle lifetime, which goes as -1 /[T2ln(T /TF) ] , in the low-temperature limit we find τv˜1 /T2 .

  20. Effect of bulk viscosity on elliptic flow near the QCD phase transition

    SciTech Connect

    Denicol, G. S.; Kodama, T.; Mota, Ph.; Koide, T.

    2009-12-15

    In this work, we examine the effect of bulk viscosity on elliptic flow, taking into account the critical behavior of the equation of state and transport coefficients near the QCD phase transition. We found that the p{sub T} dependence of v{sub 2} is quantitatively changed by the presence of the QCD phase transition. Within reasonable values of the transport coefficients, v{sub 2} decreases by a factor of 15% at small p{sub T} values (<1 GeV). However, for larger values of p{sub T} (>2 GeV), the interplay between the velocity of sound and transport coefficient near the QCD phase transition enhances v{sub 2}. We point out that Grad's 14-moment approximation cannot be applied for the calculation of the one-particle distribution function at the freeze-out.

  1. Bulk viscosity and relaxation time of causal dissipative relativistic fluid dynamics

    NASA Astrophysics Data System (ADS)

    Huang, Xu-Guang; Kodama, Takeshi; Koide, Tomoi; Rischke, Dirk H.

    2011-02-01

    The microscopic formulas of the bulk viscosity ζ and the corresponding relaxation time τΠ in causal dissipative relativistic fluid dynamics are derived by using the projection operator method. In applying these formulas to the pionic fluid, we find that the renormalizable energy-momentum tensor should be employed to obtain consistent results. In the leading-order approximation in the chiral perturbation theory, the relaxation time is enhanced near the QCD phase transition, and τΠ and ζ are related as τΠ=ζ/[β{(1/3-cs2)(ɛ+P)-2(ɛ-3P)/9}], where ɛ, P, and cs are the energy density, pressure, and velocity of sound, respectively. The predicted ζ and τΠ should satisfy the so-called causality condition. We compare our result with the results of the kinetic calculation by Israel and Stewart and the string theory, and confirm that all three approaches are consistent with the causality condition.

  2. Bulk viscosity in a hyperonic star and r-mode instability

    SciTech Connect

    Jha, T. K.; Mishra, H.; Sreekanth, V.

    2010-08-15

    We consider a rotating neutron star with the presence of hyperons in its core. We use an equation of state in an effective chiral model within the relativistic mean-field approximation. We calculate the hyperonic bulk viscosity coefficient caused by nonleptonic weak interactions. By estimating the damping time scales of the dissipative processes, we investigate its role in the suppression of gravitationally driven instabilities in the r mode. We observe that r-mode instability remains very significant for hyperon core temperatures of around 10{sup 8} K, which results in a comparatively larger instability window. We find that such instability can reduce the angular velocity of the rapidly rotating star considerably up to {approx}0.04{Omega}{sub K}, with {Omega}{sub K} as the Keplerian angular velocity.

  3. Connecting Bulk Viscosity Measurements to Kinetic Limitations on Attaining Equilibrium for a Model Aerosol Composition

    NASA Astrophysics Data System (ADS)

    Topping, D. O.; Murphy, B.; Riipinen, I.; Percival, C.; Booth, A.

    2014-12-01

    The growth, composition, and evolution of secondary organic aerosol (SOA) are governed by properties of individual compounds and ensemble mixtures that affect partitioning between the vapor and condensed phase. There has been considerable recent interest in the idea that SOA can form highly viscous particles where the diff usion of either water or semivolatile organics within the particle is suffi ciently hindered to aff ect evaporation and growth. Despite numerous indirect inferences of viscous behavior from SOA evaporation or " bounce" within aerosol instruments, there have been no bulk measurements of the viscosity of well-constrained model aerosol systems of atmospheric signifi cance. Here the viscous behavior of a well-defi ned model system of 9 dicarboxylic acids is investigated directly with complementary measurements and model predictions used to infer phase state. Results not only allow us to discuss the atmospheric implications for SOA formation through this representative mixture, but also the potential impact of current methodologies used for probing this aff ect in both the laboratory and from a modeling perspective. We show, quantitatively, that the physical state transformation from liquid-like to amorphous semisolid can substantially increase the importance of mass transfer limitations within particles by 7 orders of magnitude for 100 nm diameter particles. Recommendations for future research directions are given.

  4. Mantle viscosity - A comparison of models from postglacial rebound and from the geoid, plate driving forces, and advected heat flux

    NASA Technical Reports Server (NTRS)

    Hager, Bradford H.

    1991-01-01

    Models of the radial variation of effective viscosity inferred from the earth's response to surface loads associated with Pleistocene deglaciation are compared to structures inferred from models of geodynamic phenomena associated with convection: the geoid, plate-driving forces, and advected heat flux. While observations of the earth's response to surface loads do not have sufficient resolution to justify more than two viscous layers, adequately matching the observed long-wavelength geoid anomalies associated with density contrasts in the lower mantle (inferred from seismic tomography) and in the upper mantle (inferred from a model of subducted slabs) requires more structure. It is possible to explain the geoid, observed plate velocities, the advected heat flux in the lower mantle, and relative sea-level variations in oceanic regions, all with a mantle with a high-viscosity/elastic lid, an asthenospheric channel of 2 x 10 exp 19 Pa s from 100 to 400-km depth, a 6 x 10 exp 20 Pa s transition zone, and a lower mantle of 6 x 10 exp 21 Pa s. The uplift history of Australia, Fennoscandia, and Laurentia can be explained with an asthenospheric viscosity less than a factor of 10 higher. Lateral variations in lower mantle viscosity are not required. Transient creep appears to be unimportant for the recent response-to-surface loads from Pleistocene deglaciation.

  5. Shear and bulk viscosities of quark matter from quark-meson fluctuations in the Nambu-Jona-Lasinio model

    NASA Astrophysics Data System (ADS)

    Ghosh, Sabyasachi; Peixoto, Thiago C.; Roy, Victor; Serna, Fernando E.; Krein, Gastão

    2016-04-01

    We have calculated the temperature dependence of shear η and bulk ζ viscosities of quark matter due to quark-meson fluctuations. The quark thermal width originating from quantum fluctuations of quark-π and quark-σ loops at finite temperature is calculated with the formalism of real-time thermal field theory. Temperature-dependent constituent-quark and meson masses and quark-meson couplings are obtained in the Nambu-Jona-Lasinio model. We found a nontrivial influence of the temperature-dependent masses and couplings on the Landau-cut structure of the quark self-energy. Our results for the ratios η /s and ζ /s , where s is the entropy density (also determined in the Nambu-Jona-Lasinio model in the quasiparticle approximation), are in fair agreement with results of the literature obtained from different models and techniques. In particular, our result for η /s has a minimum very close to the quantum lower bound, η /s =1 /4 π .

  6. ITER ECH launcher options for start-up assist, bulk heating, and EC current drive experiments

    SciTech Connect

    Bigelow, T.S.

    1994-03-01

    Electron Cyclotron Heating (ECH) is proposed for providing plasma start-up, bulk heating, current drive, and other applications on the International Tokamak Experimental Reactor (ITER) project. The requirements for ECH power launching systems for ITER have been investigated, and several possible configurations that have been devised are described in this report. The proposed launcher designs use oversized circular corrugated waveguides that make small penetrations through the blanket modules and radiate into the plasma. The criteria used for the design calls for minimum blanket penetration area, maximum reliability, and optimum launched beam quality. The effects of the harsh plasma edge environment on the launcher are discussed. Power generation systems, windows, and other components of the ECH systems are also investigated. The designs presented are believed to be capable of operating reliably and are relatively easy to maintain remotely.

  7. The disordered P granule protein LAF-1 drives phase separation into droplets with tunable viscosity and dynamics

    PubMed Central

    Elbaum-Garfinkle, Shana; Kim, Younghoon; Szczepaniak, Krzysztof; Chen, Carlos Chih-Hsiung; Eckmann, Christian R.; Myong, Sua; Brangwynne, Clifford P.

    2015-01-01

    P granules and other RNA/protein bodies are membrane-less organelles that may assemble by intracellular phase separation, similar to the condensation of water vapor into droplets. However, the molecular driving forces and the nature of the condensed phases remain poorly understood. Here, we show that the Caenorhabditis elegans protein LAF-1, a DDX3 RNA helicase found in P granules, phase separates into P granule-like droplets in vitro. We adapt a microrheology technique to precisely measure the viscoelasticity of micrometer-sized LAF-1 droplets, revealing purely viscous properties highly tunable by salt and RNA concentration. RNA decreases viscosity and increases molecular dynamics within the droplet. Single molecule FRET assays suggest that this RNA fluidization results from highly dynamic RNA–protein interactions that emerge close to the droplet phase boundary. We demonstrate than an N-terminal, arginine/glycine rich, intrinsically disordered protein (IDP) domain of LAF-1 is necessary and sufficient for both phase separation and RNA–protein interactions. In vivo, RNAi knockdown of LAF-1 results in the dissolution of P granules in the early embryo, with an apparent submicromolar phase boundary comparable to that measured in vitro. Together, these findings demonstrate that LAF-1 is important for promoting P granule assembly and provide insight into the mechanism by which IDP-driven molecular interactions give rise to liquid phase organelles with tunable properties. PMID:26015579

  8. Dependence of the frequency dispersion of the bulk viscosity coefficient of solutions of electrolytes on the nature of the decay of relaxing fluxes

    NASA Astrophysics Data System (ADS)

    Odinaev, S.; Akdodov, D. M.

    2016-06-01

    The region of the frequency dispersion of the bulk viscosity coefficient η V (ω) of solutions of electrolytes is studied as a function of the nature of the decay of the stress tensor in the momentum and configuration space, the analytical expressions of which are derived by means of kinetic equations. Numerical calculations of η V (ω) for a water solution of NaCl are performed over a wide range of frequencies, temperatures, and densities using a selection of the potentials of intermolecular interaction Φ{in{itab}}(|ěc r|) and radial distribution function {itg}{in{itab}}(|ěc r|). It is shown that the region of frequency dispersion η V (ω) based on the power law of the decay of the stress tensor is wide ( 105 Hz), while the region based on the exponential law is narrow ( 102 Hz).

  9. Hall viscosity

    NASA Astrophysics Data System (ADS)

    Read, Nicholas

    2015-03-01

    Viscosity is a transport coefficient relating to transport of momentum, and usually thought of as the analog of friction that occurs in fluids and solids. More formally, it is the response of the stress to the gradients of the fluid velocity field, or to the rate of change of strain (derivatives of displacement from a reference state). In general, viscosity is described by a fourth-rank tensor. Invoking rotation invariance, it reduces to familiar shear and bulk viscosity parts, which describe dissipation, but it can also contain an antisymmetric part, analogous to the Hall conductivity part of the conductivity tensor. In two dimensions this part is a single number, the Hall viscosity. Symmetry of the system under time reversal (or, in two dimensions, reflections) forces it to vanish. In quantum fluids with a gap in the bulk energy spectrum and which lack both time reversal and reflection symmetries the Hall viscosity can be nonzero even at zero temperature. For integer quantum Hall states, it was first calculated by Avron, Seiler, and Zograf, using a Berry curvature approach, analogous to the Chern number for Hall conductivity. In 2008 this was extended by the present author to fractional quantum Hall states and to BCS states in two dimensions. I found that the general result is given by a simple formula ns / 2 , where n is the particle number density, and s is the ``orbital spin'' per particle. The spin s is also related to the shift S, which enters the relation between particle number and magnetic flux needed to put the ground state on a surface of non-trivial topology with introducing defect excitations, by S = 2 s ; the connection was made by Wen and Zee. The values of s and S are rational numbers, and are robust--unchanged under perturbations that do not cause the bulk energy gap to collapse--provided rotation as well as translation symmetry are maintained. Hall viscosity can be measured in principle, though a simple way to do so is lacking. It enters various

  10. The detection of lubricating oil viscosity changes in gearbox transmission systems driven by sensorless variable speed drives using electrical supply parameters

    NASA Astrophysics Data System (ADS)

    Abusaad, S.; Brethee, K.; Assaeh, M.; Zhang, R.; Gu, F.; Ball, A. D.

    2015-07-01

    Lubrication oil plays a decisive role to maintain a reliable and efficient operation of gear transmissions. Many offline methods have been developed to monitor the quality of lubricating oils. This work focus on developing a novel online method to diagnose oil degradation based on the measurements from power supply system to the gearbox. Experimental studies based on an 10kW industrial gearbox fed by a sensorless variable speed drive (VSD) shows that measurable changes in both static power and dynamic behaviour are different with lube oils tested. Therefore, it is feasible to use the static power feature to indicate viscosity changes at low and moderate operating speeds. In the meantime, the dynamic feature can separate viscosity changes for all different tested cases.

  11. Surface dilatational viscosity of Langmuir monolayers

    NASA Astrophysics Data System (ADS)

    Lopez, Juan; Vogel, Michael; Hirsa, Amir

    2003-11-01

    With increased interest in microfluidic systems, interfacial phenomena is receiving more attention. As the length scales of fluid problems decrease, the surface to volume ratio increases and the coupling between interfacial flow and bulk flow becomes increasingly dominated by effects due to intrinsic surface viscosities (shear and dilatational), in comparison to elastic effects (due to surface tension gradients). The surface shear viscosity is well-characterized, as cm-scale laboratory experiments are able to isolate its effects from other interfacial processes (e.g., in the deep-channel viscometer). The same is not true for the dilatational viscosity, because it acts in the direction of surface tension gradients. Their relative strength scale with the capillary number, and for cm-scale laboratory flows, surface tension effects tend to dominate. In microfluidic scale flows, the scaling favors viscosity. We have devised an experimental apparatus which is capable of isolating and enhancing the effects of dilatational viscosity at the cm scales by driving the interface harmonically in time, while keeping the interface flat. In this talk, we shall present both the theory for how this works as well as experimental measurements of surface velocity from which we deduce the dilatational viscosity of several monolayers on the air-water interface over a substantial range of surface concentrations. Anomalous behavior over some range of concentration, which superficially indicates negative viscosity, maybe explained in terms of compositional effects due to large spatial and temporal variations in concentration and corresponding viscosity.

  12. Simultaneous measurement of speed of sound, thermal diffusivity, and bulk viscosity of 1-ethyl-3-methylimidazolium-based ionic liquids using laser-induced gratings.

    PubMed

    Kozlov, Dimitrii N; Kiefer, Johannes; Seeger, Thomas; Fröba, Andreas P; Leipertz, Alfred

    2014-12-11

    The technique of laser-induced gratings (LIGs) has been applied to the simultaneous determination of speed of sound and thermal diffusivity of four 1-ethyl-3-methylimidazolium ([EMIm])-based room temperature ionic liquids (RTILs)-[EMIm][N(CN)2], [EMIm][MeSO3], [EMIm][C(CN)3], and [EMIm][NTf2]-at ambient pressure (1 bar (0.1 MPa)) and temperature (28 °C (301 K)). Transient laser-induced gratings were created as a result of thermalization of a quasi-resonant excitation of highly lying combinational vibrational states of the RTIL molecules and electrostrictive compression of the liquid by radiation of a pulse-repetitive Q-switched Nd:YAG pump laser (1064 nm). The LIGs temporal evolution was recorded using Bragg diffraction of the radiation from a continuous-wave probe laser (532 nm). By fitting the temporal profiles of the LIG signals, the speed of sound and thermal diffusivity were determined, and the isentropic compressibility and thermal conductivity were calculated. Independently, the special experimental arrangement allowed the measurement of the damping of the laser-excited acoustic waves and the derivation of the RTIL bulk viscosity for the first time. PMID:25415848

  13. Inefficient Driving of Bulk Turbulence By Active Galactic Nuclei in a Hydrodynamic Model of the Intracluster Medium

    NASA Astrophysics Data System (ADS)

    Reynolds, Christopher S.; Balbus, Steven A.; Schekochihin, Alexander A.

    2015-12-01

    Central jetted active galactic nuclei (AGNs) appear to heat the core regions of the intracluster medium (ICM) in cooling-core galaxy clusters and groups, thereby preventing a cooling catastrophe. However, the physical mechanism(s) by which the directed flow of kinetic energy is thermalized throughout the ICM core remains unclear. We examine one widely discussed mechanism whereby the AGN induces subsonic turbulence in the ambient medium, the dissipation of which provides the ICM heat source. Through controlled inviscid three-dimensional hydrodynamic simulations, we verify that explosive AGN-like events can launch gravity waves (g-modes) into the ambient ICM, which in turn decays to volume-filling turbulence. In our model, however, this process is found to be inefficient, with less than 1% of the energy injected by the AGN activity actually ending up in the turbulence of the ambient ICM. This efficiency is an order of magnitude or more too small to explain the observations of AGN-feedback in galaxy clusters and groups with short central cooling times. Atmospheres in which the g-modes are strongly trapped/confined have an even lower efficiency since, in these models, the excitation of turbulence relies on the g-modes’ ability to escape from the center of the cluster into the bulk ICM. Our results suggest that, if AGN-induced turbulence is indeed the mechanism by which the AGN heats the ICM core, its driving may rely on physics beyond that captured in our ideal hydrodynamic model.

  14. Lagrangian numerical techniques for modelling multicomponent flow in the presence of large viscosity contrasts: Markers-in-bulk versus Markers-in-chain

    NASA Astrophysics Data System (ADS)

    Mulyukova, Elvira; Dabrowski, Marcin; Steinberger, Bernhard

    2015-04-01

    Many problems in geodynamic applications may be described as viscous flow of chemically heterogeneous materials. Examples include subduction of compositionally stratified lithospheric plates, folding of rheologically layered rocks, and thermochemical convection of the Earth's mantle. The associated time scales are significantly shorter than that of chemical diffusion, which justifies the commonly featured phenomena in geodynamic flow models termed contact discontinuities. These are spatially sharp interfaces separating regions of different material properties. Numerical modelling of advection of fields with sharp interfaces is challenging. Typical errors include numerical diffusion, which arises due to the repeated action of numerical interpolation. Mathematically, a material field can be represented by discrete indicator functions, whose values are interpreted as logical statements (e.g. whether or not the location is occupied by a given material). Interpolation of a discrete function boils down to determining where in the intermediate node-positions one material ends, and the other begins. The numerical diffusion error thus manifests itself as an erroneous location of the material-interface. Lagrangian advection-schemes are known to be less prone to numerical diffusion errors, compared to their Eulerian counterparts. The tracer-ratio method, where Lagrangian markers are used to discretize the bulk of materials filling the entire domain, is a popular example of such methods. The Stokes equation in this case is solved on a separate, static grid, and in order to do it - material properties must be interpolated from the markers to the grid. This involves the difficulty related to interpolation of discrete fields. The material distribution, and thus material-properties like viscosity and density, seen by the grid is polluted by the interpolation error, which enters the solution of the momentum equation. Errors due to the uncertainty of interface-location can be

  15. Hall Viscosity II: Extracting Viscosity from Conductivity

    NASA Astrophysics Data System (ADS)

    Goldstein, Moshe; Bradlyn, Barry; Read, Nicholas

    2012-02-01

    When time reversal symmetry is broken, the viscosity tensor of a fluid can have non-dissipative components, similarly to the non-dissipative off-diagonal Hall conductivity. This ``Hall viscosity'' was recently shown to be half the particle density times the orbital angular momentum per particle. Its observation can thus help elucidate the nature of the more exotic quantum Hall states and related systems (e.g., p+ip superconductors). However, no concrete measurement scheme has hitherto been proposed. Motivated by this question we use linear response theory to derive a general relation between the viscosity tensor and the wave-vector dependent conductivity tensor for a Galilean-invariant quantum fluid. This relation enables one to extract the Hall viscosity, as well as other viscosity coefficients (shear and bulk) when relevant, from electromagnetic response measurements. We also discuss the connection between this result and a similar one recently derived by C. Hoyos and D. T. Son [arXiv:1109.2651].

  16. Compositional dependence of lower crustal viscosity

    NASA Astrophysics Data System (ADS)

    Shinevar, William J.; Behn, Mark D.; Hirth, Greg

    2015-10-01

    We calculate the viscosity structure of the lower continental crust as a function of its bulk composition using multiphase mixing theory. We use the Gibbs free-energy minimization routine Perple_X to calculate mineral assemblages for different crustal compositions under pressure and temperature conditions appropriate for the lower continental crust. The effective aggregate viscosities are then calculated using a rheologic mixing model and flow laws for the major crust-forming minerals. We investigate the viscosity of two lower crustal compositions: (i) basaltic (53 wt % SiO2) and (ii) andesitic (64 wt % SiO2). The andesitic model predicts aggregate viscosities similar to feldspar and approximately 1 order of magnitude greater than that of wet quartz. The viscosity range calculated for the andesitic crustal composition (particularly when hydrous phases are stable) is most similar to independent estimates of lower crust viscosity in actively deforming regions based on postglacial isostatic rebound, postseismic relaxation, and paleolake shoreline deflection.

  17. Viscosity-stabilized aqueous solutions

    SciTech Connect

    Wier, D. R.

    1981-01-27

    Thiourea functions as a solution viscosity stabilizer in aqueous compositions comprising thiourea, nonionic polymers such as polyalkylene oxides and anionic surfactants such as petroleum sulfonates. The aqueous compositions are useful in connection with fluid-drive oil recovery processes, processes for drilling, completing, or working over wells, or the like processes in which a thickened fluid is injected into or brought into contact with a subterranean earth formation.

  18. Viscosity of Common Seed and Vegetable Oils

    NASA Astrophysics Data System (ADS)

    Wes Fountain, C.; Jennings, Jeanne; McKie, Cheryl K.; Oakman, Patrice; Fetterolf, Monty L.

    1997-02-01

    Viscosity experiments using Ostwald-type gravity flow viscometers are not new to the physical chemistry laboratory. Several physical chemistry laboratory texts (1 - 3) contain at least one experiment studying polymer solutions or other well-defined systems. Several recently published articles (4 - 8) indicated the continued interest in using viscosity measurements in the teaching lab to illustrate molecular interpretation of bulk phenomena. Most of these discussions and teaching experiments are designed around an extensive theory of viscous flow and models of molecular shape that allow a full data interpretation to be attempted. This approach to viscosity experiments may not be appropriate for all teaching situations (e.g., high schools, general chemistry labs, and nonmajor physical chemistry labs). A viscosity experiment is presented here that is designed around common seed and vegetable oils. With the importance of viscosity to foodstuffs (9) and the importance of fatty acids to nutrition (10), an experiment using these common, recognizable oils has broad appeal.

  19. Anisotropic eddy viscosity models

    NASA Technical Reports Server (NTRS)

    Carati, D.; Cabot, W.

    1996-01-01

    A general discussion on the structure of the eddy viscosity tensor in anisotropic flows is presented. The systematic use of tensor symmetries and flow symmetries is shown to reduce drastically the number of independent parameters needed to describe the rank 4 eddy viscosity tensor. The possibility of using Onsager symmetries for simplifying further the eddy viscosity is discussed explicitly for the axisymmetric geometry.

  20. Hydrophilicity and the viscosity of interfacial water.

    PubMed

    Goertz, Matthew P; Houston, J E; Zhu, X-Y

    2007-05-01

    We measure the viscosity of nanometer-thick water films at the interface with an amorphous silica surface. We obtain viscosity values from three different measurements: friction force in a water meniscus formed between an oxide-terminated W tip and the silica surface under ambient conditions; similar measurements for these interfaces under water; and the repulsive "drainage" force as the two surfaces approach at various speeds in water. In all three cases, we obtain effective viscosities that are approximately 10(6) times greater than that of bulk water for nanometer-scale interfacial separations. This enhanced viscosity is not observed when we degrade the hydrophilicity of the surface by terminating it with -H or -CH3. In view of recent results from other interfaces, we conclude that the criterion for the formation of a viscous interphase is the degree of hydrophilicity of the interfacial pair. PMID:17408290

  1. Nonequilibrium viscosity of glass

    NASA Astrophysics Data System (ADS)

    Mauro, John C.; Allan, Douglas C.; Potuzak, Marcel

    2009-09-01

    Since glass is a nonequilibrium material, its properties depend on both composition and thermal history. While most prior studies have focused on equilibrium liquid viscosity, an accurate description of nonequilibrium viscosity is essential for understanding the low temperature dynamics of glass. Departure from equilibrium occurs as a glass-forming system is cooled through the glass transition range. The glass transition involves a continuous breakdown of ergodicity as the system gradually becomes trapped in a subset of the available configurational phase space. At very low temperatures a glass is perfectly nonergodic (or “isostructural”), and the viscosity is described well by an Arrhenius form. However, the behavior of viscosity during the glass transition range itself is not yet understood. In this paper, we address the problem of glass viscosity using the enthalpy landscape model of Mauro and Loucks [Phys. Rev. B 76, 174202 (2007)] for selenium, an elemental glass former. To study a wide range of thermal histories, we compute nonequilibrium viscosity with cooling rates from 10-12 to 1012K/s . Based on these detailed landscape calculations, we propose a simplified phenomenological model capturing the essential physics of glass viscosity. The phenomenological model incorporates an ergodicity parameter that accounts for the continuous breakdown of ergodicity at the glass transition. We show a direct relationship between the nonequilibrium viscosity parameters and the fragility of the supercooled liquid. The nonequilibrium viscosity model is validated against experimental measurements of Corning EAGLE XG™ glass. The measurements are performed using a specially designed beam-bending apparatus capable of accurate nonequilibrium viscosity measurements up to 1016Pas . Using a common set of parameters, the phenomenological model provides an accurate description of EAGLE XG™ viscosity over the full range of measured temperatures and fictive temperatures.

  2. Viscosity in a lepton-photon universe

    NASA Astrophysics Data System (ADS)

    Husdal, Lars

    2016-08-01

    We look at viscosity production in a universe consisting purely of leptons and photons. This is quite close to what the universe actually look like when the temperature was between 10^{10} K and 10^{12} K (1-100 MeV). By taking the strong force and the hadronic particles out of the equation, we can examine how the viscous forces behave with all the 12 leptons present. By this we study how shear- and (more interestingly) bulk viscosity is affected during periods with particle annihilation. We use the theory given by Hoogeveen et al. from 1986, replicate their 9-particle results and expanded it to include the muon and tau particles as well. This will impact the bulk viscosity immensely for high temperatures. We will show that during the beginning of the lepton era, when the temperature is around 100 MeV, the bulk viscosity will be roughly 100 million times larger with muons included in the model compared to a model without.

  3. Viscosity of paraproteinemic sera.

    PubMed

    Tichý, M

    1996-01-01

    Viscosity was determined in a series of 1402 paraproteinemic sera. Viscosity was measured on an ultrasonic viscosimeter of domestic design and was expressed in relative units(ru). Increased viscosity over 2.1 ru was found in 288 sera, i.e. 20.5%. Clinical symptoms of the hyperviscosity syndrome were found in 44 cases (3%) with viscosity over 4.0 ru. Malignant monoclonal gammopathy as proved in all 44 cases. In 17 determinations with the presence of paraprotein IgM, the mean viscosity was 6.35% +/- 2.6 ru, and the mean paraprotein concentration was 41.12 +/- 11.26g/l. In 17 cases we found paraprotein IgG with a mean viscosity of 6.38 +/- 2.4 ru and a mean concentration of paraprotein was 63.66 +/- 14.52g/l. In 9 determinations with the presence of paraprotein IgA, the mean viscosity as 5.22 +/- 1.02 ru and the mean paraprotein concentration was 49.77 +/- 13.89g/1. In one case we found a double paraproteinemia of IgG-lambda + IgA-kappa (31.9 + 24.2g/l), with a viscosity of 10.5 ru. PMID:9106390

  4. Viscosity measuring using microcantilevers

    DOEpatents

    Oden, Patrick Ian

    2001-01-01

    A method for the measurement of the viscosity of a fluid uses a micromachined cantilever mounted on a moveable base. As the base is rastered while in contact with the fluid, the deflection of the cantilever is measured and the viscosity determined by comparison with standards.

  5. Viscosity and Solvation

    ERIC Educational Resources Information Center

    Robertson, C. T.

    1973-01-01

    Discusses theories underlying the phenomena of solution viscosities, involving the Jones and Dole equation, B-coefficient determination, and flickering cluster model. Indicates that viscosity measurements provide a basis for the study of the structural effects of ions in aqueous solutions and are applicable in teaching high school chemistry. (CC)

  6. Viscosity of a nanoconfined liquid during compression

    SciTech Connect

    Khan, Shah H.; Kramkowski, Edward L.; Ochs, Peter J.; Wilson, David M.; Hoffmann, Peter M.

    2014-01-13

    The viscous behavior of liquids under nanoconfinement is not well understood. Using a small-amplitude atomic force microscope, we found bulk-like viscosity in a nanoconfined, weakly interacting liquid. A further decrease in viscosity was observed at confinement sizes of a just few molecular layers. Overlaid over the continuum viscous behavior, we measured non-continuum stiffness and damping oscillations. The average stiffness of the confined liquid was found to scale linearly with the size of the confining tip, while the damping scales with the radius of curvature of the tip end.

  7. Viscosity in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.; Shu, F. H.; Cuzzi, J. N.

    1982-01-01

    The technique of estimating the viscosity in Saturn's rings from the damping rate of waves observed to be propagating within the rings is discussed. The wavetrains of attempts using spiral density waves as a diagnostic suffer significant complications that compromise the interpretations. A method that considers the damping of spiral bending waves was used to deduce a kinematic viscosity of 260 (+150, -100) sqcm/sec for the middle of the A ring where bending waves are excited by the 5:3 vertical resonance with Mimas. This value implies upper limits on the particle velocity dispersion and local ring thickness of 0.4 cm/sec and 30 m, respectively.

  8. Longitudinal viscosity of two-dimensional Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Goree, J.; Liu, Bin

    2013-01-01

    The longitudinal viscosity ηl is obtained for a two-dimensional (2D) liquid using a Green-Kubo method with a molecular dynamics simulation. The interparticle potential used has the Debye-Hückel or Yukawa form, which models a 2D dusty plasma. The longitudinal ηl and shear ηs viscosities are found to have values that match very closely, with only negligible differences for the entire range of temperatures that is considered. For a 2D Yukawa liquid, the bulk viscosity ηb is determined to be either negligibly small or not a meaningful transport coefficient.

  9. Damping of drop oscillations by surfactants and surface viscosity

    NASA Technical Reports Server (NTRS)

    Rush, Brian M.; Nadim, Ali

    1999-01-01

    An energy equation is derived for the general case of a viscous drop suspended in a viscous medium with surfactants contaminating the interface. It contains terms that clearly identify dissipation contributions from the viscous effects in the bulk fluids, surface shear and dilatational viscosity effects at the interface, and surfactant transport. An efficient boundary integral method is developed which incorporates the effects of a constant surface dilatational viscosity in simulations of an oscillating two-dimensional inviscid drop. Surface dilatational viscosity is shown to have a significant damping effect on the otherwise undamped inviscid oscillations.

  10. Viscosity of colloidal suspensions

    SciTech Connect

    Cohen, E.G.D.; Schepper, I.M. de

    1995-12-31

    Simple expressions are given for the effective Newtonian viscosity as a function of concentration as well as for the effective visco-elastic response as a function of concentration and imposed frequency, of monodisperse neutral colloidal suspensions over the entire fluid range. The basic physical mechanisms underlying these formulae are discussed. The agreement with existing experiments is very good.

  11. Hydrodynamics and viscosity in the Rindler spacetime

    NASA Astrophysics Data System (ADS)

    Eling, Christopher; Chirco, Goffredo; Liberati, Stefano

    2012-07-01

    In the past year it has been shown that one can construct an approximate (d + 2) dimensional solution of the vacuum Einstein equations dual to a (d + 1) dimensional fluid satisfying the Navier-Stokes equations. The construction proceeds by perturbing the flat Rindler metric, subject to the boundary conditions of a non-singular causal horizon in the interior and a fixed induced metric on a given timelike surface r = rc in the bulk. We review this fluid-Rindler correspondence and show that the shear viscosity to entropy density ratio of the fluid on r = rc takes the universal value 1/4π both in Einstein gravity and in a wide class of higher curvature generalizations. Since the precise holographic duality for this spacetime is unknown, we propose a microscopic explanation for this viscosity based on the peculiar properties of quantum entanglement. Using a novel holographic Kubo formula in terms of a two-point function of the stress tensor of matter fields in the bulk, we calculate a shear viscosity and find that the ratio with respect to the entanglement entropy density is exactly 1/4π in four dimensions.

  12. Viscosity of Campi Flregrei (Italy) magmas

    NASA Astrophysics Data System (ADS)

    Misiti, Valeria; Vetere, Francesco; Scarlato, Piergiorgio; Behrens, Harald; Mangiacapra, Annarita; Freda, Carmela

    2010-05-01

    Viscosity is an important factor governing both intrusive and volcanic processes. The most important parameters governing silicate melts viscosity are bulk composition of melt and temperature. Pressure has only minor effect at crustal depths, whereas crystals and bubbles have significant influence. Among compositional parameters, the water content is critical above all in terms of rheological behaviour of melts and explosive style of an eruption. Consequently, without an appropriate knowledge of magma viscosity depending on the amount of dissolved volatiles, it is not possible to model the processes (i.e., magma ascent, fragmentation, and dispersion) required to predict realistic volcanic scenarios and thus forecast volcanic hazards. The Campi Flegrei are a large volcanic complex (~150 km2) located west of the city of Naples, Italy, that has been the site of volcanic activity for more than 60 ka and represents a potential volcanic hazard owing to the large local population. In the frame of a INGV-DPC (Department of Civil Protection) project devoted to design a multidisciplinary system for short-term volcano hazard evaluation, we performed viscosity measurements, under dry and hydrous conditions, of primitive melt compositions representative of two Campi Flegrei eruptions (Minopoli-shoshonite and Fondo Riccio-latite). Viscosity of the two melts have been investigated in the high temperature/low viscosity range at atmospheric pressure in dry samples and at 0.5 GPa in runs having water content from nominally anhydrous to about 3 wt%. Data in the low temperature/high viscosity range were obtained near the glass transition temperature at atmospheric pressure on samples whose water contents vary from 0.3 up to 2.43 wt%. The combination of high- and low-viscosity data permits a general description of the viscosity as a function of temperature and water content using a modified Tamman-Vogel-Fulcher equation. logν = a+ --b--+ --d--×exp(g × w-) (T - c) (T - e) T (1) where

  13. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

  14. MEMS fluid viscosity sensor.

    PubMed

    Ballato, Arthur

    2010-03-01

    Quartz shear resonators are employed widely as sensors to measure Newtonian viscosities of liquids. Perturbation of the electrical equivalent circuit parameters of the plate resonator by the fluid loading permits calculation of the mass density-shear viscosity product. Use of doubly rotated resonators does permit additional information to be obtained, but in no case can the viscosity and mass density values be separated. In these measurements, the resonator surface is exposed to a measurand bath whose extent greatly exceeds the penetration depth of the evanescent shear mode excited by the active element. Here we briefly review past techniques and current art, and sketch a proposal involving the interesting situation in which the separation between the resonator and a confining wall is less than the penetration depth of the fluid occupying the intervening region. To highlight the salient features of this novel case, the discussion is limited to the very idealized circumstance of a strictly 1-D problem, unencumbered by the vicissitudes inevitably encountered in practice. An appendix mentions some of these functional impedimenta and indicates how deviations from ideality might be approached in engineering embodiments. When the fluid confinement is of the order of the penetration depth, the resonator perturbation becomes a sensitive function of the separation, and it is found that viscosity and density may be separately and uniquely determined. Moreover, extreme miniaturization is a natural consequence because the penetration depth generally is on the order of micrometers for frequencies around 1 MHz at temperatures and pressures ordinarily encountered with gases and liquids. Micro-electro-mechanical (MEMS) versions of viscometers and associated types of fluid sensors are thereby enabled. PMID:20211786

  15. Crustal Viscosity Structure Estimated from Multi-Phase Mixing Theory

    NASA Astrophysics Data System (ADS)

    Shinevar, W. J.; Behn, M. D.; Hirth, G.

    2014-12-01

    Estimates of lower crustal viscosity are typically constrained by analyses of isostatic rebound, post seismic creep, and laboratory-derived flow laws for crustal rocks and minerals. Here we follow a new approach for calculating the viscosity structure of the lower continental crust. We use Perple_X to calculate mineral assemblages for different crustal compositions. Effective viscosity is then calculated using the rheologic mixing model of Huet et al. (2014) incorporating flow laws for each mineral phase. Calculations are performed along geotherms appropriate for the Basin and Range, Tibetan Plateau, Colorado Plateau, and the San Andreas Fault. To assess the role of crustal composition on viscosity, we examined two compositional gradients extending from an upper crust with ~67 wt% SiO2 to a lower crust that is either: (i) basaltic with ~53 wt% SiO2 (Rudnick and Gao, 2003), or (ii) andesitic with ~64% SiO2 (Hacker et al., 2011). In all cases, the middle continental crust has a viscosity that is 2-3 orders of magnitude greater than that inferred for wet quartz, a common proxy for mid-crustal viscosities. An andesitic lower crust results in viscosities of 1020-1021 Pa-s and 1021-1022 Pa-s for hotter and colder crustal geotherms, respectively. A mafic lower crust predicts viscosities that are an order of magnitude higher for the same geotherm. In all cases, the viscosity calculated from the mixing model decreases less with depth compared to single-phase estimates. Lastly, for anhydrous conditions in which alpha quartz is stable, we find that there is a strong correlation between Vp/Vs and bulk viscosity; in contrast, little to no correlation exists for hydrous conditions.

  16. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The sample cell at the heart of CVX-2 will sit inside a thermostat providing three layers of insulation. The cell itself comprises a copper body that conducts heat efficiently and smoothes out thermal variations that that would destroy the xenon's uniformity. Inside the cell, the oscillating screen viscometer element is supported between two pairs of electrodes that deflect the screen and then measure screen motion.

  17. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2001 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure that is placed inside a pressure canister. A similar canister holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD. This is a detail view of MSFC 0100143.

  18. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

  19. Critical exponent for viscosity

    NASA Technical Reports Server (NTRS)

    Berg, Robert F.; Moldover, Michael R.

    1990-01-01

    The critical exponent y characterizing the divergence of the viscosity for carbon dioxide and xenon has been measured. The values of y for both fluids fall within the range y = 0.041 + or - 0.001 and are consistent with the range y = 0.042 + or - 0.002 spanned by earlier data for four binary liquid mixtures. This agreement is the strongest evidence that pure fluids and binary liquids are in the same dynamic universality class; however, the results for y are inconsistent with the recent theoretical value of 0.032.

  20. The Jeans instability criterion for a compressible fluid including viscosity and heat conduction

    NASA Astrophysics Data System (ADS)

    Corona-Galindo, M. G.; Dehnen, H.

    1989-03-01

    For the region after the recombination era of the universe, the hydrodynamical density waves are analyzed, including shear viscosity and heat conduction for densities equal to and less than the critical density of the universe. Very near to the end of the recombination era (z = 1200), the well-known Jeans instability is found. Although the influence of the shear viscosity on the instabilities is negligible, a visible influence of the bulk viscosity is found to be present.

  1. Feasibility of density and viscosity measurements under ammonothermal conditions

    NASA Astrophysics Data System (ADS)

    Steigerwald, Thomas G.; Alt, Nicolas S. A.; Hertweck, Benjamin; Schluecker, Eberhard

    2014-10-01

    With an eye on numerical simulations of ammonothermal growth of group III-V bulk single crystals, precise data for viscosity and density are strongly needed. In this work, changes in viscosity depending on temperature and pressure are traced in the developed ball viscometer. There, the falling time is detected by acquiring the acoustic signal of the ball using a high temperature borne-noise acceleration sensor. The results for the viscosity of pure ammonia at ammonothermal conditions already show good accuracy. The apparatus is designed to measure the density in addition to the viscosity, by the substitution of the rolling ball material in later experiments. This is important because the density of the flowing fluid is not constant due to the solubility change of GaN in ammonia by the mineralizers obligatory in ammonothermal process.

  2. Bulk undercooling

    NASA Technical Reports Server (NTRS)

    Kattamis, T. Z.

    1984-01-01

    Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.

  3. Viscosity of Hydrous Rhyolitic Melts

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Xu, Z.; Liu, Y.

    2002-12-01

    It is critical to understand and to be able to predict viscosity of hydrous silicate melts for understanding magma transport, bubble growth, volcanic eruptions, and magma fragmentation. We report new viscosity data for hydrous rhyolitic melt in the viscosity range of 109 to 1015 Pa s based on the kinetics of hydrous species reaction in the melt upon cooling (i.e., based on the equivalence between the glass transition temperature and the apparent equilibrium temperature). We also report viscosity data obtained from bubble growth experiments. Our data show that the viscosity model of Hess and Dingwell (1996) systematically overestimates the viscosity of hydrous rhyolitic melt at the high viscosity range by a factor of 2 to 4 (still within their stated 2σ uncertainty). Another problem with the model of Hess and Dingwell is that the functional dependence of viscosity on total H2O content cannot be extended to dry melt: as total H2O content decreases to zero, the viscosity would first increase, and then decrease to zero. A zero viscosity for a dry melt makes no sense. Hence we need a mixing law for hydrous melt viscosity that is extendible to dry melts. By examining the viscosity of rhyolitic melts containing 6 ppm to about 8.0 wt% total H2O (both our own data and literature data), we propose the following relation for the dependence of viscosity on total H2O content: 1/η = 1/η 1+(1/η 2-1/η 1)xn ≈ 1/η 1+xn/η 2 where η is viscosity and 1/η is fluidity, η 1 is the viscosity of the dry melt, x is the mole fraction of total dissolved H2O, n and η 2 are two fitting parameters, and η 2 can be identified to be the viscosity of the hypothetical melt consisting of pure H2O (η 2 cannot be directly measured since such a melt does not exist). The above equation appears to work well for the viscosity of hydrous rhyolitic melts. By fitting hydrous rhyolitic melt viscosity with the above equation, we find that rhyolitic melt viscosity vary by 1.2 orders of magnitude

  4. Experimental understanding of the viscosity reduction ability of TLCPs with different PEs

    NASA Astrophysics Data System (ADS)

    Tang, Youhong; Zuo, Min; Gao, Ping

    2014-08-01

    In this study, two thermotropic liquid crystalline polyesters (TLCPs) synthesized by polycondensation of p-hydroxybenzoic acid /hydroquinone/ poly dicarboxylic acid were used as viscosity reduction agents for polyethylene (PE). The TLCPs had different thermal, rheological and other physical properties that were quantitatively characterized. The two TLCPs were blended with high density PE (HDPE) and high molecular mass PE (HMMPE) by simple twin screw extrusion under the same weight ratio of 1.0 wt% and were each rheologically characterized at 190°C. The TLCPs acted as processing modifiers for the PEs and the bulk viscosity of the blends decreased dramatically. However, the viscosity reduction ability was not identical: one TLCP had obviously higher viscosity reduction ability on the HDPE, with a maximum viscosity reduction ratio of 68.1%, whereas the other TLCP had higher viscosity reduction ability on the HMMPE, with a maximum viscosity reduction ratio of 98.7%. Proposed explanations for these differences are evaluated.

  5. Viscosity of the earth's core.

    NASA Technical Reports Server (NTRS)

    Gans, R. F.

    1972-01-01

    Calculation of the viscosity of the core at the boundary of the inner and outer core. It is assumed that this boundary is a melting transition and the viscosity limits of the Andrade (1934,1952) hypothesis (3.7 to 18.5 cp) are adopted. The corresponding kinematic viscosities are such that the precessional system explored by Malkus (1968) would be unstable. Whether it would be sufficiently unstable to overcome a severely subadiabatic temperature gradient cannot be determined.

  6. High-Frequency Shear Viscosity of Low-Viscosity Liquids

    NASA Astrophysics Data System (ADS)

    Kaatze, U.; Behrends, R.

    2014-11-01

    A thickness shear quartz resonator technique is described to measure the shear viscosity of low-viscosity liquids in the frequency range from 6 MHz to 130 MHz. Examples of shear-viscosity spectra in that frequency range are presented to show that various molecular processes are accompanied by shear-viscosity relaxation. Among these processes are conformational variations of alkyl chains, with relaxation times of about 0.3 ns for -pentadecane and -hexadecane at 25 C. These variations can be well represented in terms of a torsional oscillator model. Also featured briefly are shear-viscosity relaxations associated with fluctuations of hydrogen-bonded clusters in alcohols, for which values between 0.3 ns (-hexanol) and 1.5 ns (-dodecanol) have been found at 25 C. In addition, the special suitability of high-frequency shear-viscosity spectroscopy to the study of critically demixing mixtures is demonstrated by some illustrative examples. Due to slowing, critical fluctuations do not contribute to the shear viscosity at sufficiently high frequencies of measurements so that the non-critical background viscosity of critical systems can be directly determined from high-frequency shear-viscosity spectroscopy. Relaxations in appear also in the shear-viscosity spectra with, for example, 2 ns for the critical triethylamine-water binary mixture at temperatures between 10 C and 18 C. Such relaxations noticeably influence the relaxation rate of order parameter fluctuations. They may be also the reason for the need of a special mesoscopic viscosity when mutual diffusion coefficients of critical polymer solutions are discussed in terms of mode-coupling theory.

  7. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of liquid xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Resembling a tiny bit of window screen, the oscillator at the heart of CVX-2 will vibrate between two pairs of paddle-like electrodes. The slight bend in the shape of the mesh has no effect on the data. What counts are the mesh's displacement in the xenon fluid and the rate at which the displacement dampens. The unit shown here is encased in a small test cell and capped with a sapphire windown to contain the xenon at high pressure.

  8. Viscosity measuring instrument

    NASA Technical Reports Server (NTRS)

    Feinstein, S. P. (Inventor)

    1980-01-01

    A method and apparatus are provided for enabling the measurement of the viscosity of substances, especially those containing volatiles at elevated temperatures, with greater accuracy and at less cost than before. The apparatus includes a cylinder with a narrow exit opening at one end and a piston which closely slides within the cylinder to apply force against a sample in the cylinder to force the sample through the exit opening. In order to more rapidly heat a sample the ends of the cylinder and piston are tapered and the sample is correspondingly tapered, to provide a large surface to volume ratio. A corresponding coal sample is formed by compressing particles of coal under high pressure in a mold of appropriate shape.

  9. Size effects and the role of density on the viscosity of water confined in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Köhler, Mateus Henrique; da Silva, Leandro Barros

    2016-02-01

    Equilibrium molecular dynamics simulations were carried out in order to determine the viscosity of water confined into carbon nanotubes. We have found that the viscosity of confined water is about an order of magnitude lower than bulk and increase non-linearly with nanotube diameter. We quantify the influence of density of water upon its viscosity, and observed a strong dependence between both quantities. After analysis of density profiles and diffusion coefficients we conclude that water at high density regime experiences a structural transition resulting in a large increment in viscosity.

  10. Volatiles Which Increase Magma Viscosity

    NASA Astrophysics Data System (ADS)

    Webb, S.

    2015-12-01

    The standard model of an erupting volcano is one in which the viscosity of a decompressing magma increases as the volatiles leave the melt structure to form bubbles. It has now been observed that the addition of the "volatiles" P, Cl and F result in an increase in silicate melt viscosity. This observation would mean that the viscosity of selected degassing magmas would decrease rather than increase. Here we look at P, Cl and F as three volatiles which increase viscosity through different structural mechanisms. In all three cases the volatiles increase the viscosity of peralkaline composition melts, but appear to always decrease the viscosity of peraluminous melts. Phosphorus causes the melt to unmix into a Na-P rich phase and a Na-poor silicate phase. Thus as the network modifying Na (or Ca) are removed to the phosphorus-rich melt, the matrix melt viscosity increases. With increasing amounts of added phosphorus (at network modifying Na ~ P) the addition of further phosphorus causes a decrease in viscosity. The addition of chlorine to Fe-free aluminosilicate melts results in an increase in viscosity. NMR data on these glass indicates that the chlorine sits in salt-like structures surrounded by Na and/or Ca. Such structures would remove network-modifying atoms from the melt structure and thus result in an increase in viscosity. The NMR spectra of fluorine-bearing glasses shows that F takes up at least 5 different structural positions in peralkaline composition melts. Three of these positions should result in a decrease in viscosity due to the removal of bridging oxygens. Two of the structural positons of F, however, should result in an increase in viscosity as they require the removal of network-modifying atoms from the melt structure (with one of the structures being that observed for Cl). This would imply that increasing amounts of F might result in an increase in viscosity. This proposed increase in viscosity with increasing F has now been experimentally confirmed.

  11. Conservative smoothing versus artificial viscosity

    SciTech Connect

    Guenther, C.; Hicks, D.L.; Swegle, J.W.

    1994-08-01

    This report was stimulated by some recent investigations of S.P.H. (Smoothed Particle Hydrodynamics method). Solid dynamics computations with S.P.H. show symptoms of instabilities which are not eliminated by artificial viscosities. Both analysis and experiment indicate that conservative smoothing eliminates the instabilities in S.P.H. computations which artificial viscosities cannot. Questions were raised as to whether conservative smoothing might smear solutions more than artificial viscosity. Conservative smoothing, properly used, can produce more accurate solutions than the von Neumann-Richtmyer-Landshoff artificial viscosity which has been the standard for many years. The authors illustrate this using the vNR scheme on a test problem with known exact solution involving a shock collision in an ideal gas. They show that the norms of the errors with conservative smoothing are significantly smaller than the norms of the errors with artificial viscosity.

  12. ZBLAN Viscosity Instrumentation

    NASA Technical Reports Server (NTRS)

    Kaukler, William

    2001-01-01

    The past year's contribution from Dr. Kaukler's experimental effort consists of these 5 parts: a) Construction and proof-of-concept testing of a novel shearing plate viscometer designed to produce small shear rates and operate at elevated temperatures; b) Preparing nonlinear polymeric materials to serve as standards of nonlinear Theological behavior; c) Measurements and evaluation of above materials for nonlinear rheometric behavior at room temperature using commercial spinning cone and plate viscometers available in the lab; d) Preparing specimens from various forms of pitch for quantitative comparative testing in a Dynamic Mechanical Analyzer, Thermal Mechanical Analyzer; and Archeological Analyzer; e) Arranging to have sets of pitch specimens tested using the various instruments listed above, from different manufacturers, to form a baseline of the viscosity variation with temperature using the different test modes offered by these instruments by compiling the data collected from the various test results. Our focus in this project is the shear thinning behavior of ZBLAN glass over a wide range of temperature. Experimentally, there are no standard techniques to perform such measurements on glasses, particularly at elevated temperatures. Literature reviews to date have shown that shear thinning in certain glasses appears to occur, but no data is available for ZBLAN glass. The best techniques to find shear thinning behavior require the application of very low rates of shear. In addition, because the onset of the thinning behavior occurs at an unknown elevated temperature, the instruments used in this study must provide controlled low rates of shear and do so for temperatures approaching 600 C. In this regard, a novel shearing parallel plate viscometer was designed and a prototype built and tested.

  13. Viscosity Measurement for Tellurium Melt

    NASA Technical Reports Server (NTRS)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2006-01-01

    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  14. Fluid Merging Viscosity Measurement (FMVM)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Astronaut Mike Fincke places droplets of honey onto the strings for the Fluid Merging Viscosity Measurement (FMVM) investigation onboard the International Space Station (ISS). The FMVM experiment measures the time it takes for two individual highly viscous fluid droplets to coalesce or merge into one droplet. Different fluids and droplet size combinations were tested in the series of experiments. By using the microgravity environment, researchers can measure the viscosity or 'thickness' of fluids without the influence of containers and gravity using this new technique. Understanding viscosity could help scientists understand industrially important materials such as paints, emulsions, polymer melts and even foams used to produce pharmaceutical, food, and cosmetic products.

  15. Critical Viscosity of Xenon investigators

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Dr. Dr. Robert F. Berg (right), principal investigator and Dr. Micheal R. Moldover (left), co-investigator, for the Critical Viscosity of Xenon (CVX/CVX-2) experiment. They are with the National Institutes of Standards and Technology, Gaithersburg, MD. The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of chemicals.

  16. iDriving (Intelligent Driving)

    Energy Science and Technology Software Center (ESTSC)

    2012-09-17

    iDriving identifies the driving style factors that have a major impact on fuel economy. An optimization framework is used with the aim of optimizing a driving style with respect to these driving factors. A set of polynomial metamodels is constructed to reflect the responses produced in fuel economy by changing the driving factors. The optimization framework is used to develop a real-time feedback system, including visual instructions, to enable drivers to alter their driving stylesmore » in responses to actual driving conditions to improve fuel efficiency.« less

  17. iDriving (Intelligent Driving)

    SciTech Connect

    Malikopoulos, Andreas

    2012-09-17

    iDriving identifies the driving style factors that have a major impact on fuel economy. An optimization framework is used with the aim of optimizing a driving style with respect to these driving factors. A set of polynomial metamodels is constructed to reflect the responses produced in fuel economy by changing the driving factors. The optimization framework is used to develop a real-time feedback system, including visual instructions, to enable drivers to alter their driving styles in responses to actual driving conditions to improve fuel efficiency.

  18. Viscosity Depressants for Coal Liquefaction

    NASA Technical Reports Server (NTRS)

    Kalfayan, S. H.

    1983-01-01

    Proposed process modification incorporates viscosity depressants to prevent coal from solidifying during liquefaction. Depressants reduce amount of heat needed to liquefy coal. Possible depressants are metallic soaps, such as stearate, and amides, such as stearamide and dimer acid amides.

  19. Viscous Moment, Mechanism of Slow Slip, and Subduction Megathrust Viscosity

    NASA Astrophysics Data System (ADS)

    Fagereng, A.

    2015-12-01

    Slow slip events (SSEs) represent transient slip velocities slower than earthquakes but faster than steady, average plate motion. SSEs repeating at the same location have characteristic slip magnitude and duration. Contrary to earthquakes, however, average slip relates to neither duration nor area. Variations in duration, slip, and slip rate can instead be tied to variations in effective viscosity, calculated from a viscous definition of moment. In this paradigm, the observation that deep slow slip events are slower and longer, implies a higher effective viscosity than in shallower, colder SSEs. Observed variations in effective viscosity and slip rate can be interpreted in terms of differences in driving stress and shear zone width, and likely arise in anastomosing shear zones containing a heterogeneous mixture of materials.

  20. Dark matter perturbations and viscosity: A causal approach

    NASA Astrophysics Data System (ADS)

    Acquaviva, Giovanni; John, Anslyn; Pénin, Aurélie

    2016-08-01

    The inclusion of dissipative effects in cosmic fluids modifies their clustering properties and could have observable effects on the formation of large-scale structures. We analyze the evolution of density perturbations of cold dark matter endowed with causal bulk viscosity. The perturbative analysis is carried out in the Newtonian approximation and the bulk viscosity is described by the causal Israel-Stewart (IS) theory. In contrast to the noncausal Eckart theory, we obtain a third-order evolution equation for the density contrast that depends on three free parameters. For certain parameter values, the density contrast and growth factor in IS mimic their behavior in Λ CDM when z ≥1 . Interestingly, and contrary to intuition, certain sets of parameters lead to an increase of the clustering.

  1. Solvent viscosity dependence for enzymatic reactions

    NASA Astrophysics Data System (ADS)

    Sitnitsky, A. E.

    2008-09-01

    A mechanism for relationship of solvent viscosity with reaction rate constant at enzyme action is suggested. It is based on fluctuations of electric field in enzyme active site produced by thermally equilibrium rocking (crankshaft motion) of the rigid plane (in which the dipole moment ≈3.6 D lies) of a favourably located and oriented peptide group (or may be a few of them). Thus the rocking of the plane leads to fluctuations of the electric field of the dipole moment. These fluctuations can interact with the reaction coordinate because the latter in its turn has transition dipole moment due to separation of charges at movement of the reacting system along it. The rocking of the plane of the peptide group is sensitive to the microviscosity of its environment in protein interior and the latter is a function of the solvent viscosity. Thus we obtain an additional factor of interrelationship for these characteristics with the reaction rate constant. We argue that due to the properties of the crankshaft motion the frequency spectrum of the electric field fluctuations has a sharp resonance peak at some frequency and the corresponding Fourier mode can be approximated as oscillations. We employ a known result from the theory of thermally activated escape with periodic driving to obtain the reaction rate constant and argue that it yields reliable description of the pre-exponent where the dependence on solvent viscosity manifests itself. The suggested mechanism is shown to grasp the main feature of this dependence known from the experiment and satisfactorily yields the upper limit of the fractional index of a power in it.

  2. Impaired Driving

    MedlinePlus

    ... Risk Factors BAC Effects Prevention Additional Resources How big is the problem? In 2014, 9,967 people ... Driving: A Threat to Everyone (October 2011) Additional Data Drunk Driving State Data and Maps Motor Vehicle ...

  3. Drugged Driving

    MedlinePlus

    ... Infographics » Drugged Driving Drugged Driving Email Facebook Twitter Text Description of Infographic Top Right Figure : In 2009, ... crash than those who don't smoke. Bottom Text: Develop Social Strategies Offer to be a designated ...

  4. Global scaling symmetry, Noether charge, and universality of shear viscosity

    NASA Astrophysics Data System (ADS)

    Liu, Hai-Shan

    2016-05-01

    Recently, it was established in Einstein-Maxwell-Dilaton gravity that the Kovtun-Son-Starinets viscosity/entropy ratio associated with anti-de Sitter planar black holes can be viewed as the boundary dual to the generalized Smarr relation of the black holes in the bulk. In this paper, we establish this relation in Einstein gravity with general minimally coupled matter and also in theories with an additional nonminimally coupled scalar field. We consider two examples for explicit demonstrations.

  5. Viscosity and scale invariance in the unitary Fermi gas

    SciTech Connect

    Enss, Tilman; Haussmann, Rudolf; Zwerger, Wilhelm

    2011-03-15

    We compute the shear viscosity of the unitary Fermi gas above the superfluid transition temperature, using a diagrammatic technique that starts from the exact Kubo formula. The formalism obeys a Ward identity associated with scale invariance which guarantees that the bulk viscosity vanishes identically. For the shear viscosity, vertex corrections and the associated Aslamazov-Larkin contributions are shown to be crucial to reproduce the full Boltzmann equation result in the high-temperature, low fugacity limit. The frequency dependent shear viscosity {eta}({omega}) exhibits a Drude-like transport peak and a power-law tail at large frequencies which is proportional to the Tan contact. The weight in the transport peak is given by the equilibrium pressure, in agreement with a sum rule due to Taylor and Randeria. Near the superfluid transition the peak width is of the order of 0.5T{sub F}, thus invalidating a quasiparticle description. The ratio {eta}/s between the static shear viscosity and the entropy density exhibits a minimum near the superfluid transition temperature whose value is larger than the string theory bound h/(4{pi}k{sub B}) by a factor of about seven.

  6. Demonstrating the Importance of Bubbles and Viscosity on Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Namiki, A.

    2005-12-01

    The behavior of bubbles (exsolved volatile from magma) and viscosity of magma are important parameters that influence volcanic eruptions. Exsolved volatiles increase the volume of magma and reduce its density so that magma has sufficient volume and buoyancy force to erupt. Volatiles exsolve through nucleation and growth by diffusion and bubbles can expand as pressure is reduced. The time scale of diffusion depends on the viscosity of surrounding magma, and the expansion time scale of a bubble is also depends on the viscosity of magma. These control the time scale for volume change. If bubbles segregate from magma and collapse, the magma might not able to expand sufficiently to erupt violently. Whether a bubble can segregate from the liquid part of magma is also depends on viscosity of magma. In this poster, I introduce a straightforward demonstration to show the importance of bubbles and viscosity of magma on volcanic eruptions. To make bubbles, I use baking soda (NaHCO3) and citric acid. Reaction between them generates carbon dioxide (CO2) to make bubbles. I make citric acid solution gel by using agar at the bottom of a transparent glass and pour baking soda disolved corn syrup on top of the agar. This situation is a model of basally heated magma chamber. When water disolved magma (baking soda disolved corn syrup) receives sufficient heat (citric acid) bubbles are generated. I can change viscosity of corn syrup by varying the concentration of water. This demonstration shows how viscosity controls the time scale of volume change of bubbly magma and the distribution of bubbles in the fluid. In addition it helps to understand the important physical processes in volcanic eruption: bubble nucleation, diffusion grows, expansion, and bubble driving convection. I will perform a live demonstration at the site of the poster.

  7. Viscosities of aqueous blended amines

    SciTech Connect

    Hsu, C.H.; Li, M.H.

    1997-07-01

    Solutions of alkanolamines are an industrially important class of compounds used in the natural gas, oil refineries, petroleum chemical plants, and synthetic ammonia industries for the removal of acidic components like CO{sub 2} and H{sub 2}S from gas streams. The viscosities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA), DEA + 2-amino-2-methyl-1-propanol (AMP), and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) were measured from 30 C to 80 C. A Redlich-Kister equation for the viscosity deviation was applied to represent the viscosity. On the basis of the available viscosity data for five ternary systems, MEA + MDEA + H{sub 2}O, MEA + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. For the viscosity calculation of the systems tested, the overall average absolute percent deviation is about 1.0% for a total of 499 data points.

  8. Influence of object concentration on finite strain and effective viscosity contrast: insights from naturally deformed packstones

    NASA Astrophysics Data System (ADS)

    Vitale, Stefano; Mazzoli, Stefano

    Deformed conglomerates and ooidal/oncoidal packstones are commonly used to evaluate finite strain in deformed sedimentary successions. In order to obtain a correct estimate of finite strain, it is necessary to consider not only the different behaviour of matrix and objects, but also object concentration. The analysis of two-component rocks characterised by high values of packing commonly results in a substantial underestimate of bulk strain and of viscosity contrast between objects and matrix. In this study, the effects of the volumetric fraction of competent inclusions on both object and bulk measured finite strain, as well as on apparent viscosity contrast, have been investigated in naturally deformed packstones characterised by variable object concentration on the scale of the hand specimen (and hence for homogenous viscosity contrast). Object finite strain has been obtained by Rf/ ϕ analysis, whereas the Fry method provides a measure of whole-rock strain that is also a function of inclusion concentration. Therefore, the finite strain measured by the Fry method is better termed effective bulk strain. In order to investigate the role of object concentration, this parameter has been plotted against object and effective bulk strain, and also against viscosity contrast. These diagrams show that: (i) for high values of packing, measured object and effective bulk strain show values that are significantly lower with respect to the calculated maximum value (that would result in the ideal case of no particle interaction and represents therefore the real bulk strain of the samples); (ii) the viscosity contrast shows lower values with respect to the calculated maximum one (that is equal for the three principal sections of the finite strain ellipsoid), and as packing reaches the maximum value, the viscosity contrast approaches a unit value. Empirical equations have also been found that link object concentration with both object and effective bulk finite strain.

  9. Pile Driving

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

  10. Plasma viscosity in spherical ICF implosion simulations

    NASA Astrophysics Data System (ADS)

    Vold, E.; Joglekar, A.; Ortega, M.; Moll, R.; Fenn, D.; Molvig, K.

    2016-05-01

    Inertial confinement fusion (ICF) hydrodynamic codes often ignore the effects of viscosity though recent research indicates plasma viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. A Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport, and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation, is used to study differences between ICF implosions with and without plasma viscosity and to examine the role of artificial viscosity in a Lagrangian implosion simulation. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, fuel compression, and time history of neutron production rates. Plasma viscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and this study suggests that artificial viscosity may provide an unphysical stability in implosion simulations.

  11. The Effects of Preeruptive Magma Viscosity on Eruption Styles and Magma Eruption Rates

    NASA Astrophysics Data System (ADS)

    Tomiya, A.; Koyaguchi, T.; Kozono, T.; Takeuchi, S.

    2014-12-01

    We have collected data on magma eruption rate, which is one of the most fundamental parameters for a volcanic eruption. There are several compilations on eruption rates, for example, for Plinian eruptions (Carey and Sigurdsson, 1989), basaltic eruptions (Wadge, 1981), lava dome eruptions (Newhall and Melson, 1983), and all combined (Tomiya and Koyaguchi, 1998; Pyle, 2000). However, they did not quantitatively discuss the effects of magma viscosity, which must control eruption rates. Here, we discuss the effects of magma viscosity on eruption rates, by using 'preeruptive magma viscosities', which are important measures of magma eruptibility (Takeuchi, 2011). Preeruptive magma viscosity is the viscosity of magma (melt, dissolved water, and crystals) in the magma chamber at the preeruptive conditions, and can be approximately obtained only by the bulk rock SiO2 and phenocryst content, using an empirical formula (Takeuchi, 2010). We have found some interesting relationships, such as (1) eruption styles and rates are correlated to preeruptive magma viscosity but not correlated to bulk rock composition, and (2) the gap (ratio) in eruption rates between explosive and effusive phases in a series of eruptions is proportional to preeruptive magma viscosity. We also propose, by combining (1) and (2), that (3) the radius (or width) of volcanic conduit is positively correlated with preeruptive magma viscosity. Our data also show that the eruptive magmas are divided into two types. One is the low-viscosity type (basalt ~ phenocryst-poor andesite), characterized by lava flow and sub-Plinian eruptions. The other is the high-viscosity type (phenocryst-rich andesite ~ rhyolite), characterized by lava dome and Plinian eruptions. The boundary is at about 104 Pa s. These two types may be closely linked to the magma generation processes (fractional/batch crystallization vs. extraction from a mushy magma chamber).

  12. Viscosity in spherically symmetric accretion

    NASA Astrophysics Data System (ADS)

    Ray, Arnab K.

    2003-10-01

    The influence of viscosity on the flow behaviour in spherically symmetric accretion has been studied here. The governing equation chosen has been the Navier-Stokes equation. It has been found that at least for the transonic solution, viscosity acts as a mechanism that detracts from the effectiveness of gravity. This has been conjectured to set up a limiting scale of length for gravity to bring about accretion, and the physical interpretation of such a length scale has been compared with the conventional understanding of the so-called `accretion radius' for spherically symmetric accretion. For a perturbative presence of viscosity, it has also been pointed out that the critical points for inflows and outflows are not identical, which is a consequence of the fact that under the Navier-Stokes prescription, there is a breakdown of the invariance of the stationary inflow and outflow solutions - an invariance that holds good under inviscid conditions. For inflows, the critical point gets shifted deeper within the gravitational potential well. Finally, a linear stability analysis of the stationary inflow solutions, under the influence of a perturbation that is in the nature of a standing wave, has indicated that the presence of viscosity induces greater stability in the system than has been seen for the case of inviscid spherically symmetric inflows.

  13. Light Effect on Water Viscosity: Implication for ATP Biosynthesis

    NASA Astrophysics Data System (ADS)

    Sommer, Andrei P.; Haddad, Mike Kh.; Fecht, Hans-Jörg

    2015-07-01

    Previous work assumed that ATP synthase, the smallest known rotary motor in nature, operates at 100% efficiency. Calculations which arrive to this result assume that the water viscosity inside mitochondria is constant and corresponds to that of bulk water. In our opinion this assumption is not satisfactory for two reasons: (1) There is evidence that the water in mitochondria prevails to 100% as interfacial water. (2) Laboratory experiments which explore the properties of interfacial water suggest viscosities which exceed those of bulk water, specifically at hydrophilic interfaces. Here, we wish to suggest a physicochemical mechanism which assumes intramitochondrial water viscosity gradients and consistently explains two cellular responses: The decrease and increase in ATP synthesis in response to reactive oxygen species and non-destructive levels of near-infrared (NIR) laser light, respectively. The mechanism is derived from the results of a new experimental method, which combines the technique of nanoindentation with the modulation of interfacial water layers by laser irradiation. Results, including the elucidation of the principle of light-induced ATP production, are expected to have broad implications in all fields of medicine.

  14. Light Effect on Water Viscosity: Implication for ATP Biosynthesis

    PubMed Central

    Sommer, Andrei P.; Haddad, Mike Kh.; Fecht, Hans-Jörg

    2015-01-01

    Previous work assumed that ATP synthase, the smallest known rotary motor in nature, operates at 100% efficiency. Calculations which arrive to this result assume that the water viscosity inside mitochondria is constant and corresponds to that of bulk water. In our opinion this assumption is not satisfactory for two reasons: (1) There is evidence that the water in mitochondria prevails to 100% as interfacial water. (2) Laboratory experiments which explore the properties of interfacial water suggest viscosities which exceed those of bulk water, specifically at hydrophilic interfaces. Here, we wish to suggest a physicochemical mechanism which assumes intramitochondrial water viscosity gradients and consistently explains two cellular responses: The decrease and increase in ATP synthesis in response to reactive oxygen species and non-destructive levels of near-infrared (NIR) laser light, respectively. The mechanism is derived from the results of a new experimental method, which combines the technique of nanoindentation with the modulation of interfacial water layers by laser irradiation. Results, including the elucidation of the principle of light-induced ATP production, are expected to have broad implications in all fields of medicine. PMID:26154113

  15. Concentration dependence of the effective viscosity of polymer solutions in small pores with repulsive or attractive walls

    SciTech Connect

    Chauveteau, G.; Tirrell, M.; Omari, A.

    1984-07-01

    Polymer solutions are demonstrated to have apparent viscosities in small pores which depend on pore diameter (or the mean diameter of pore throats in irregular porous media) and which, therefore, can be considerably different from the viscosity of the same solution in an unbounded medium. The apparent viscosities in the pores can be greater or less than in bulk depending upon whether the pore wall is attractive or repulsive for the polymer. Specifically, if there is no adsorption (repulsive wall) we find that the solution viscosity is always less inside the pore than in bulk. On the other hand if the wall is attractive the apparent solution viscosity inside the pore may be greater or less, depending on the concentration of the flowing polymer solution. Data representing these effects are presented for aqueous solutions of hydrolyzed polyacrylamide and xanthan polysaccharide. The data are organized as suggested by a model recently proposed by Chauveteau for polymer solution flow in small pores. 47 references.

  16. Magnetic microrheometer for in situ characterization of coating viscosity.

    PubMed

    Song, Jin-Oh; Henry, Robert M; Jacobs, Ryan M; Francis, Lorraine F

    2010-09-01

    A magnetic microrheometer has been designed to characterize the local viscosity of liquid-applied coatings in situ during solidification. The apparatus includes NdFeB magnets mounted on computer-controlled micropositioners for the manipulation of ∼1 μm diameter superparamagnetic particles in the coating. Magnetic field gradients at 20-70 T/m are generated by changing magnet size and the gap distance between the magnets. A specimen stage located between two magnets is outfitted with a heater and channels to control process conditions (temperature and air flow), and a digital optical microscope lens above the stage is used to monitor the probe particle position. Validation studies with glycerol and polyimide precursor solution showed that microrheometry results match traditional bulk rheometry within an error of 5%. The viscosities of polyvinyl alcohol (PVA) solution and polyimide precursor solution coatings were measured at different shear rates (0.01-5 s(-1)) by adjusting the magnetic field gradient. The effect of proximity to the substrate on the particle motion was characterized and compared with theoretical predictions. The magnetic microrheometer was used to characterize the time-viscosity profile of PVA coatings during drying at several temperatures. The viscosity range measured by the apparatus was 0.1-20 Pa s during drying of coatings at temperatures between room temperature and 80 °C. PMID:20886990

  17. Universal viscosity to entropy density ratio from entanglement

    SciTech Connect

    Chirco, Goffredo; Eling, Christopher; Liberati, Stefano

    2010-07-15

    We present evidence that the universal Kovtun-Son-Starinets shear viscosity to entropy density ratio of 1/4{pi} can be associated with a Rindler causal horizon in flat spacetime. Since there is no known holographic (gauge/gravity) duality for this spacetime, a natural microscopic explanation for this viscosity is in the peculiar properties of quantum entanglement. In particular, it is well known that the Minkowski vacuum state is a thermal state and carries an area entanglement entropy density in the Rindler spacetime. Based on the fluctuation-dissipation theorem, we expect a similar notion of viscosity arising from vacuum fluctuations. Therefore, we propose a holographic Kubo formula in terms of a two-point function of the stress tensor of matter fields in the bulk. We calculate this viscosity assuming a minimally coupled scalar field theory and find that the ratio with respect to the entanglement entropy density is exactly 1/4{pi} in four dimensions. The issues that arise in extending this result to nonminimally coupled scalar fields, higher spins, and higher dimensions provide interesting hints about the relationship between entanglement entropy and black hole entropy.

  18. Magnetic microrheometer for in situ characterization of coating viscosity

    NASA Astrophysics Data System (ADS)

    Song, Jin-Oh; Henry, Robert M.; Jacobs, Ryan M.; Francis, Lorraine F.

    2010-09-01

    A magnetic microrheometer has been designed to characterize the local viscosity of liquid-applied coatings in situ during solidification. The apparatus includes NdFeB magnets mounted on computer-controlled micropositioners for the manipulation of ˜1 μm diameter superparamagnetic particles in the coating. Magnetic field gradients at 20-70 T/m are generated by changing magnet size and the gap distance between the magnets. A specimen stage located between two magnets is outfitted with a heater and channels to control process conditions (temperature and air flow), and a digital optical microscope lens above the stage is used to monitor the probe particle position. Validation studies with glycerol and polyimide precursor solution showed that microrheometry results match traditional bulk rheometry within an error of 5%. The viscosities of polyvinyl alcohol (PVA) solution and polyimide precursor solution coatings were measured at different shear rates (0.01-5 s-1) by adjusting the magnetic field gradient. The effect of proximity to the substrate on the particle motion was characterized and compared with theoretical predictions. The magnetic microrheometer was used to characterize the time-viscosity profile of PVA coatings during drying at several temperatures. The viscosity range measured by the apparatus was 0.1-20 Pa s during drying of coatings at temperatures between room temperature and 80 °C.

  19. Neoclassical viscosity effects on resistive magnetohydrodynamic modes in toroidal geometry

    SciTech Connect

    Yang, J.G.; Oh, Y.H.; Choi, D.I. ); Kim, J.Y.; Horton, W. )

    1992-03-01

    The flux-surface-averaged linearized resistive magnetohydrodynamic (MHD) boundary-layer equations including the compressibility, diamagnetic drift, and neoclassical viscosity terms are derived in toroidal geometry. These equations describe the resistive layer dynamics of resistive MHD modes over the collisionality regime between the banana plateau and the Pfirsch--Schlueter. From the resulting equations, the effects of neoclassical viscosity on the stability of the tearing and resistive ballooning modes are investigated numerically. Also, a study is given for the problem of how the neoclassical resistive MHD mode is generated as the collisionality is reduced. It is shown that the neoclassical viscosity terms give a significant destabilizing effect for the tearing and resistive ballooning modes. This destabilization comes mainly from the reduction of the stabilizing effect of the parallel ion sound compression by the ion neoclassical viscosity. In the banana-plateau collisionality limit, where the compressibility is negligible, the dispersion relations of the tearing and resistive ballooning modes reduce to the same form, with the threshold value of the driving force given by {Delta}{sub {ital c}}=0. On the other hand, with the finite neoclassical effect it is found that the neoclassical resistive MHD instability is generated in agreement with previous results. Furthermore, it is shown that this later instability can be generated in a wide range of the collisionality including near the Pfirsch--Schlueter regime as well as the banana-plateau regime, suggesting that this mode is a probable cause of anomalous transport.

  20. Surface tensions, viscosities, and diffusion constants in mixed component single aerosol particles

    NASA Astrophysics Data System (ADS)

    Bzdek, Bryan; Marshall, Frances; Song, Young-Chul; Haddrell, Allen; Reid, Jonathan

    2016-04-01

    Surface tension and viscosity are important aerosol properties but are challenging to measure on individual particles owing to their small size and mass. Aerosol viscosity impacts semivolatile partitioning from the aerosol phase, molecular diffusion in the bulk of the particle, and reaction kinetics. Aerosol surface tension impacts how particles activate to serve as cloud condensation nuclei. Knowledge of these properties and how they change under different conditions hinders accurate modelling of aerosol physical state and atmospheric impacts. We present measurements made using holographic optical tweezers to directly determine the viscosity and surface tension of optically trapped droplets containing ~1-4 picolitres of material (corresponding to radii of ~5-10 micrometres). Two droplets are captured in the experimental setup, equilibrated to a relative humidity, and coalesced through manipulation of the relative trap positions. The moment of coalescence is captured using camera imaging as well as from elastically backscattered light connected to an oscilloscope. For lower viscosity droplets, the relaxation in droplet shape to a sphere follows the form of a damped oscillator and gives the surface tension and viscosity. For high viscosity droplets, the relaxation results in a slow merging of the two droplets to form a sphere and the timescale of that process permits determination of viscosity. We show that droplet viscosity and surface tension can be quantitatively determined to within <10% of the expected value for low viscosity droplets and to better than 1 order of magnitude for high viscosity droplets. Examples illustrating how properties such as surface tension can change in response to environmental conditions will be discussed. Finally, a study of the relationship between viscosity, diffusion constants, vapour pressures, and reactive uptake coefficients for a mixed component aerosol undergoing oxidation and volatilisation will be discussed.

  1. Viscosity of the earth's core

    NASA Technical Reports Server (NTRS)

    Hide, R.

    1972-01-01

    Estimates of the coefficient of kinematical viscosity nu of the earth's liquid metallic core that are given in the geophysical literature range from approximately 0.001 sq cm/s, the viscosity of molten iron at ordinary pressures, to approximately less than 10 to the 8th power sq cm/s, based on the observation that compressional waves traverse the core without suffering serious attenuation. Bumps on the core-mantle boundary with typical horizontal dimensions up to a few thousand km and vertical dimensions h of a few km would produce the topographic coupling between the core and mantle that is evidently implied by the observed decade variations in the length of the day (unless the coupling is due to the presence of rapidly fluctuating magnetic fields in the core).

  2. Dynamic heterogeneity controls diffusion and viscosity near biological interfaces

    PubMed Central

    Pronk, Sander; Lindahl, Erik

    2014-01-01

    At a nanometer scale, the behavior of biological fluids is largely governed by interfacial physical chemistry. This may manifest as slowed or anomalous diffusion. Here we describe how measures developed for studying glassy systems allow quantitative measurement of interfacial effects on water dynamics, showing that correlated motions of particles near a surface result in a viscosity greater than anticipated from individual particle motions. This effect arises as a fundamental consequence of spatial heterogeneity on nanometer length scales and applies to any fluid near any surface. Increased interfacial viscosity also causes the classic finding that large solutes such as proteins diffuse much more slowly than predicted in bulk water. This has previously been treated via an empirical correction to the solute size: the hydrodynamic radius. Using measurements of quantities from theories of glass dynamics, we can now calculate diffusion constants from molecular details alone, eliminating the empirical correction factor. PMID:24398864

  3. Black brane viscosity and the Gregory-Laflamme instability

    NASA Astrophysics Data System (ADS)

    Camps, Joan; Emparan, Roberto; Haddad, Nidal

    2010-05-01

    We study long wavelength perturbations of neutral black p-branes in asymptotically flat space and show that, as anticipated in the blackfold approach, solutions of the relativistic hydrodynamic equations for an effective p + 1-dimensional fluid yield solutions to the vacuum Einstein equations in a derivative expansion. Going beyond the perfect fluid approximation, we compute the effective shear and bulk viscosities of the black brane. The values we obtain saturate generic bounds. Sound waves in the effective fluid are unstable, and have been previously related to the Gregory-Laflamme instability of black p-branes. By including the damping effect of the viscosity in the unstable sound waves, we obtain a remarkably good and simple approximation to the dispersion relation of the Gregory-Laflamme modes, whose accuracy increases with the number of transverse dimensions. We propose an exact limiting form as the number of dimensions tends to infinity.

  4. Distracted Driving

    MedlinePlus

    ... combines all three types of distraction. 3 How big is the problem? Deaths In 2013, 3,154 ... European countries. More A CDC study analyzed 2011 data on distracted driving, including talking on a cell ...

  5. Distracted driving

    MedlinePlus

    ... stay safe with a cell phone in the car. ... for Disease Control and Prevention Injury Prevention & Control. Motor Vehicle Safety. www.cdc.gov/motorvehiclesafety/distracted_driving . Accessed May ...

  6. Driving Safely

    MedlinePlus

    ... drivers’ flexibility and coordination, and reduced driving errors. S l Hand grip strengthening to help you hold on to the steering wheel l Shoulder and upper arm flexibility exercises to make ...

  7. Viscosity Index Improvers and Thickeners

    NASA Astrophysics Data System (ADS)

    Stambaugh, R. L.; Kinker, B. G.

    The viscosity index of an oil or an oil formulation is an important physical parameter. Viscosity index improvers, VIIs, are comprised of five main classes of polymers: polymethylmethacrylates (PMAs), olefin copolymers (OCPs), hydrogenated poly(styrene-co-butadiene or isoprene) (HSD/SIP/HRIs), esterified polystyrene-co-maleic anhydride (SPEs) and a combination of PMA/OCP systems. The chemistry, manufacture, dispersancy and utility of each class are described. The comparative functions, properties, thickening ability, dispersancy and degradation of VIIs are discussed. Permanent and temporary shear thinning of VII-thickened formulations are described and compared. The end-use performance and choice of VI improvers is discussed in terms of low- and high-temperature viscosities, journal bearing oil film thickness, fuel economy, oil consumption, high-temperature pumping efficiency and deposit control. Discussion of future developments concludes that VI improvers will evolve to meet new challenges of increased thermal-oxidative degradation from increased engine operating temperatures, different base stocks of either synthetic base oils or vegetable oil-based, together with alcohol- or vegetable oil-based fuels. VI improvers must also evolve to deal with higher levels of fuel dilution and new types of sludge and also enhanced low-temperature requirements.

  8. Liquid Viscosities of Fluorinated Dialkylethers

    NASA Astrophysics Data System (ADS)

    Nakazawa, Noriaki; Kawamura, Mitsutaka; Sekiya, Akira; Ootake, Katsuto; Tamai, Ryoichi; Kurokawa, Yuji; Murata, Junji

    The liquid viscosities of thirteen fluorinated dialkylethers which are expected as promising candidates of CFC alternatives were measured at temperatures from 276 K to 328 K and atmospheric pressure. The fluorinated dialkylethers used in this study are 1-methoxy-1, 1, 2, 2- tetrafluoroethane; 1-difluoromethoxy- 1, 1 , 2 -trifluoroethane; 1-methoxy-1, 1 , 2 , 2 , 3 , 3 -hexafluoropropane; 1-methoxy-1-trifluoro-methyl-2, 2 , 2-trifluoroethane; 1-difluoro-methoxy-2, 2, 3, 3-tetrafluoropropane; 1-(2, 2, 2-trifruoroethoxy)-1, 1, 2, 2-tetrafluoroethane 1-difluoromethoxy-2, 2, 3, 3, 3-pentafluoropropane 1-methoxy-2, 2, 3, 3 -tetrafluoropropane; 1-methoxy-1, 1, 2, 2, 3, 3, 3-heptafluoropropane; 1-pentafluoroethoxy-1, 1, 2, 2-tetrafluoroethane; 2-trifluoromethoxy-1, 1, 1, 2-tetrafluorobutane; 1-proxy-nonafluorobutane; and 1-ethoxyundeca-fluoropentane. The liquid viscosities have been measured by the torsionally vibrating viscometer (YAMAICHI DENKI, F VM-80A) within an uncertainty of ±3%.The liquid viscosities of those compounds decrease exponentially with increase of temperature.

  9. Density and viscosity of lipids under pressure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a lack of data for the viscosity of lipids under pressure. The current report is a part of the effort to fill this gap. The viscosity, density, and elastohydrodynamic film thicknesses of vegetable oil (HOSuO) were investigated. Pressure–viscosity coefficients (PVC) of HOSuO at different tem...

  10. Viscosity of concentrated solutions and of human erythrocyte cytoplasm determined from NMR measurement of molecular correlation times. The dependence of viscosity on cell volume.

    PubMed

    Endre, Z H; Kuchel, P W

    1986-08-01

    Metabolically active human erythrocytes were incubated with [alpha-13C]glycine which led to the specific enrichment of intracellular glutathione. The cells were then studied using 13C-NMR in which the longitudinal relaxation times (T1) and nuclear Overhauser enhancements of the free glycine and glutathione were measured. The T1 values of labelled glycine were also determined in various-concentration solutions of bovine serum albumin and glycerol and also of the natural abundance 13C of glycerol in glycerol solutions. From the T1 estimates the rotational correlation time (tau r) was calculated using a formula based on a model of an isotropic spherical rotor or that of a symmetrical ellipsoidal rotor; for glycine the differences in estimates of tau r obtained using the two models were not significant. From the correlation times and by use of the Stokes-Einstein equations viscosity and translational diffusion coefficients were calculated; thus comment can be made on the likelihood of diffusion control of certain enzyme-catalysed reactions in the erythrocyte. Bulk viscosities of the erythrocyte cytoplasm and the above-mentioned solutions were measured using Ostwald capillary viscometry. Large differences existed between the latter viscosity estimates and those based upon NMR-T1 measurements. We derived an equation from the theory of the viscosity of concentrated solutions which contains two phenomenological interaction parameters, a 'shape' factor and a 'volume' factor; it was fitted to data relating to the concentration dependence of viscosity measured by both methods. We showed, by using the equation and interaction-parameter estimates for a particular probe molecule in a particular solution, that it was possible to correlate NMR viscosity and bulk viscosity; in other words, given an estimate of the bulk viscosity, it was possible to calculate the NMR 'micro' viscosity or vice versa. However, the values of the interaction parameters depend upon the relative sizes of

  11. One atmosphere viscosity measurements of MORBs from ODP Leg 206, Hole 1256D

    NASA Astrophysics Data System (ADS)

    Sato, H.; Nakamura, H.; Ishibashi, H.

    2009-12-01

    We carried out viscosity measurements of MORBs from ODP Leg 206, Hole 1256D at one atmosphere both in hyperliquidus and subliquidus conditions. Three samples examined are #1 (core 39R1), #2(core 27R19) and #3 (core 3R4). They are typical MORBs but have different Mg/(Mg+Fe) ratios of 0.60, 0.48, and 0.42. Viscosity measurements were carried out mostly after the method of Sato (2005, J. Mineral. Petrol. Sci),. The oxygen fugacity of the furnace was controlled by mixed gas of CO2:H2(400/20ml/min), at FMQ buffer conditions. Rotational viscometer was connected to a ceramic rod of 6 mm diameter, the end of which immersed in the sample crucible 30 mm inner diameter and 60 mm high. The system is calibrated with standard viscosity oils for different depths. The samples were initially melted at ca. 50 C higher temperature than liquidus, and kept for 3 days before viscometry and sampling. After the viscometry and sampling, the furnace temperature was decreased by 5 to 30 C, and kept for 1-3 days before another viscometry and sampling. These steps are repeated until the high viscosity of the melt precluded the measurements. The quenched samples were analayzed for phase chemistry and textural features. Sample #1 crystallized plagioclase and olivine at 1215 C, followed by augite at 1205 C. Total crystal content increased to 29 vol% at 1185 C. Sample #2 crystallized plagioclase and pigeonite at 1175 C, followed by olivine and augite at 1165 C. Total crystal content increased up to 25 vol% at 1152 C. Sample #3 crystallized plagioclase, pigeonite and olivine at 1155 C. Total crystal content increased up to 25 vol% at 1133 C. Bulk viscosity increased from 46 to 74 Pa s at hyperliquidus temperatures of 1240 to 1210 C, whereas it increased up to 2908 Pa s in subliquidus temperatures of 1185 C in the sample #1. In the sample #2, bulk viscosity also increased slowly from 42 Pa s at 1232 C to 79 Pa s at 1172 C, then increased much rapidly to 3422 Pa s at 1152 C. Similarly, the sample #3

  12. Electron viscosity, current vortices and negative nonlocal resistance in graphene

    NASA Astrophysics Data System (ADS)

    Levitov, Leonid; Falkovich, Gregory

    2016-07-01

    Quantum-critical strongly correlated electron systems are predicted to feature universal collision-dominated transport resembling that of viscous fluids. However, investigation of these phenomena has been hampered by the lack of known macroscopic signatures of electron viscosity. Here we identify vorticity as such a signature and link it with a readily verifiable striking macroscopic d.c. transport behaviour. Produced by the viscous flow, vorticity can drive electric current against an applied field, resulting in a negative nonlocal voltage. We argue that the latter may play the same role for the viscous regime as zero electrical resistance does for superconductivity. Besides offering a diagnostic that distinguishes viscous transport from ohmic currents, the sign-changing electrical response affords a robust tool for directly measuring the viscosity-to-resistivity ratio. A strongly interacting electron-hole plasma in high-mobility graphene affords a unique link between quantum-critical electron transport and the wealth of fluid mechanics phenomena.

  13. Superparamagnetic nanoparticle-based viscosity test

    NASA Astrophysics Data System (ADS)

    Wu, Kai; Liu, Jinming; Wang, Yi; Ye, Clark; Feng, Yinglong; Wang, Jian-Ping

    2015-08-01

    Hyperviscosity syndrome is triggered by high blood viscosity in the human body. This syndrome can result in retinopathy, vertigo, coma, and other unanticipated complications. Serum viscosity is one of the important factors affecting whole blood viscosity, which is regarded as an indicator of general health. In this letter, we propose and demonstrate a Brownian relaxation-based mixing frequency method to test human serum viscosity. This method uses excitatory and detection coils and Brownian relaxation-dominated superparamagnetic nanoparticles, which are sensitive to variables of the liquid environment such as viscosity and temperature. We collect the harmonic signals produced by magnetic nanoparticles and estimate the viscosity of unknown solutions by comparison to the calibration curves. An in vitro human serum viscosity test is performed in less than 1.5 min.

  14. Crack evolution in bulk metallic glasses

    SciTech Connect

    Pauly, Simon; Lee, Min Ha; Kim, Do Hyang; Kim, Ki Buem; Sordelet, Daniel J.; Eckert, Juergen

    2009-11-15

    In the present study, the mechanisms underlying plastic deformation of a Ni-based bulk metallic glass (BMG) are explored. Based on the microstructural investigations, a model is proposed how fracture emerges in BMGs. After deformation, the glass is macroscopically more fragile indicating a decrease in the viscosity within the shear bands due to shear softening. These fluctuations of viscosity and therefore Poisson ratio between the deformed and undeformed regions appear to be the initiation sites for nanometer-scale cracks, which are aligned parallel to the applied force. Coalescence of voids is believed to form these small cracks, which eventually interconnect along the interface between the sheared and unsheared regions to form a detrimental defect resulting in fracture.

  15. ROTARY BULK SOLIDS DIVIDER

    DOEpatents

    Maronde, Carl P.; Killmeyer JR., Richard P.

    1992-03-03

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  16. Rotary bulk solids divider

    DOEpatents

    Maronde, Carl P.; Killmeyer, Jr., Richard P.

    1992-01-01

    An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.

  17. Bulk Fuel Man.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by bulk fuel workers. Addressed in the four individual units of the course are the following topics: bulk fuel equipment, bulk fuel systems, procedures for handling fuels, and…

  18. Effective Viscosity of Microswimmer Suspensions

    NASA Astrophysics Data System (ADS)

    Rafaï, Salima; Jibuti, Levan; Peyla, Philippe

    2010-03-01

    The measurement of a quantitative and macroscopic parameter to estimate the global motility of a large population of swimming biological cells is a challenge. Experiments on the rheology of active suspensions have been performed. Effective viscosity of sheared suspensions of live unicellular motile microalgae (Chlamydomonas Reinhardtii) is far greater than for suspensions containing the same volume fraction of dead cells. In addition, suspensions show shear thinning behavior. We relate these macroscopic measurements to the orientation of individual swimming cells under flow and discuss our results in the light of several existing models.

  19. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  20. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  1. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  2. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 2 2012-04-01 2012-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  3. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 2 2014-04-01 2014-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  4. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  5. 19 CFR 149.4 - Bulk and break bulk cargo.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 2 2013-04-01 2013-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...

  6. Linear Back-Drive Differentials

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

    Linear back-drive differentials have been proposed as alternatives to conventional gear differentials for applications in which there is only limited rotational motion (e.g., oscillation). The finite nature of the rotation makes it possible to optimize a linear back-drive differential in ways that would not be possible for gear differentials or other differentials that are required to be capable of unlimited rotation. As a result, relative to gear differentials, linear back-drive differentials could be more compact and less massive, could contain fewer complex parts, and could be less sensitive to variations in the viscosities of lubricants. Linear back-drive differentials would operate according to established principles of power ball screws and linear-motion drives, but would utilize these principles in an innovative way. One major characteristic of such mechanisms that would be exploited in linear back-drive differentials is the possibility of designing them to drive or back-drive with similar efficiency and energy input: in other words, such a mechanism can be designed so that a rotating screw can drive a nut linearly or the linear motion of the nut can cause the screw to rotate. A linear back-drive differential (see figure) would include two collinear shafts connected to two parts that are intended to engage in limited opposing rotations. The linear back-drive differential would also include a nut that would be free to translate along its axis but not to rotate. The inner surface of the nut would be right-hand threaded at one end and left-hand threaded at the opposite end to engage corresponding right- and left-handed threads on the shafts. A rotation and torque introduced into the system via one shaft would drive the nut in linear motion. The nut, in turn, would back-drive the other shaft, creating a reaction torque. Balls would reduce friction, making it possible for the shaft/nut coupling on each side to operate with 90 percent efficiency.

  7. Scientific Objectives of the Critical Viscosity Experiment

    NASA Technical Reports Server (NTRS)

    Berg, R. F.; Moldover, M. R.

    1993-01-01

    In microgravity, the Critical Viscosity Experiment will measure the viscosity of xenon 15 times closer to the critical point than is possible on earth. The results are expected to include the first direct observation of the predicted power-law divergence of viscosity in a pure fluid and they will test calculations of the value of the exponent associated with the divergence. The results, when combined with Zeno's decay-rate data, will strengthen the test of mode coupling theory. Without microgravity viscosity data, the Zeno test will require an extrapolation of existing 1-g viscosity data by as much as factor of 100 in reduced temperature. By necessity, the extrapolation would use an incompletely verified theory of viscosity crossover. With the microgravity viscosity data, the reliance on crossover models will be negligible allowing a more reliable extrapolation. During the past year, new theoretical calculations for the viscosity exponent finally achieved consistency with the best experimental data for pure fluids. This report gives the justification for the proposed microgravity Critical Viscosity Experiment in this new context. This report also combines for the first time the best available light scattering data with our recent viscosity data to demonstrate the current status of tests of mode coupling theory.

  8. Viscosity Dependence of Some Protein and Enzyme Reaction Rates: Seventy-Five Years after Kramers.

    PubMed

    Sashi, Pulikallu; Bhuyan, Abani K

    2015-07-28

    Kramers rate theory is a milestone in chemical reaction research, but concerns regarding the basic understanding of condensed phase reaction rates of large molecules in viscous milieu persist. Experimental studies of Kramers theory rely on scaling reaction rates with inverse solvent viscosity, which is often equated with the bulk friction coefficient based on simple hydrodynamic relations. Apart from the difficulty of abstraction of the prefactor details from experimental data, it is not clear why the linearity of rate versus inverse viscosity, k ∝ η(-1), deviates widely for many reactions studied. In most cases, the deviation simulates a power law k ∝ η(-n), where the exponent n assumes fractional values. In rate-viscosity studies presented here, results for two reactions, unfolding of cytochrome c and cysteine protease activity of human ribosomal protein S4, show an exceedingly overdamped rate over a wide viscosity range, registering n values up to 2.4. Although the origin of this extraordinary reaction friction is not known at present, the results indicate that the viscosity exponent need not be bound by the 0-1 limit as generally suggested. For the third reaction studied here, thermal dissociation of CO from nativelike cytochrome c, the rate-viscosity behavior can be explained using Grote-Hynes theory of time-dependent friction in conjunction with correlated motions intrinsic to the protein. Analysis of the glycerol viscosity-dependent rate for the CO dissociation reaction in the presence of urea as the second variable shows that the protein stabilizing effect of subdenaturing amounts of urea is not affected by the bulk viscosity. It appears that a myriad of factors as diverse as parameter uncertainty due to the difficulty of knowing the exact reaction friction and both mode and consequences of protein-solvent interaction work in a complex manner to convey as though Kramers rate equation is not absolute. PMID:26135219

  9. Viscosity of ring polymer melts

    PubMed Central

    Pasquino, Rossana; Vasilakopoulos, Thodoris C.; Jeong, Youn Cheol; Lee, Hyojoon; Rogers, Simon; Sakellariou, George; Allgaier, Jürgen; Takano, Atsushi; Brás, Ana R.; Chang, Taihyun; Gooßen, Sebastian; Pyckhout-Hintzen, Wim; Wischnewski, Andreas; Hadjichristidis, Nikos; Richter, Dieter; Rubinstein, Michael; Vlassopoulos, Dimitris

    2015-01-01

    We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as function of the number of entanglements Z. In the unentangled regime η0,linear/η0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/η0,ring=2. In the entanglement regime, the Z-dependence of rings viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1

  10. Bulk Superconductors in Mobile Application

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Delor, U. Floegel-; Rothfeld, R.; Riedel, T.; Wippich, D.; Goebel, B.; Schirrmeister, P.

    We investigate and review concepts of multi - seeded REBCO bulk superconductors in mobile application. ATZ's compact HTS bulk magnets can trap routinely 1 T@77 K. Except of magnetization, flux creep and hysteresis, industrial - like properties as compactness, power density, and robustness are of major device interest if mobility and light-weight construction is in focus. For mobile application in levitated trains or demonstrator magnets we examine the performance of on-board cryogenics either by LN2 or cryo-cooler application. The mechanical, electric and thermodynamical requirements of compact vacuum cryostats for Maglev train operation were studied systematically. More than 30 units are manufactured and tested. The attractive load to weight ratio is more than 10 and favours group module device constructions up to 5 t load on permanent magnet (PM) track. A transportable and compact YBCO bulk magnet cooled with in-situ 4 Watt Stirling cryo-cooler for 50 - 80 K operation is investigated. Low cooling power and effective HTS cold mass drives the system construction to a minimum - thermal loss and light-weight design.

  11. Transition of poloidal viscosity by electrode biasing in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Kitajima, S.; Takahashi, H.; Ishii, K.; Sato, Y.; Kanno, M.; Tachibana, J.; Okamoto, A.; Sasao, M.; Inagaki, S.; Takayama, M.; Masuzaki, S.; Shoji, M.; Ashikawa, N.; Tokitani, M.; Yokoyama, M.; Suzuki, Y.; Satake, S.; Ido, T.; Shimizu, A.; Suzuki, C.; Nagayama, Y.; Tokuzawa, T.; Nishimura, K.; Morisaki, T.; the LHD Experiment Group

    2013-07-01

    Electrode biasing experiments were carried out in various magnetic configurations on the Large Helical Device (LHD). The transitions of poloidal viscosity, which were accompanied with bifurcation phenomena characterized by a negative resistance in an electrode characteristic, were clearly observed on LHD by the electrode biasing. The critical external driving force required for transition was compared with the local maximum in ion viscosity, and the radial resistivity before the transition also compared with the expected value from a neoclassical theory. The critical driving force increased and the radial resistivity decreased with the major radius of the magnetic axis Rax going outwards. The configuration dependence of the transition condition and the radial resistivity qualitatively agreed with neoclassical theories. The radial electric field and the viscosity were also evaluated by the neoclassical transport code for a non-axisymmetric system, and estimated electrode voltage required for the transition, which was consistent with the experimental results.

  12. EXPERIMENTAL AND THEORETICAL DETERMINATION OF HEAVY OIL VISCOSITY UNDER RESERVOIR CONDITIONS

    SciTech Connect

    Dr. Jorge Gabitto; Maria Barrufet

    2003-05-01

    The USA deposits of heavy oils and tar sands contain significant energy reserves. Thermal methods, particularly steam drive and steam soak, are used to recover heavy oils and bitumen. Thermal methods rely on several displacement mechanisms to recover oil, but the most important is the reduction of crude viscosity with increasing temperature. The main objective of this research is to propose a simple procedure to predict heavy oil viscosity at reservoir conditions as a function of easily determined physical properties. This procedure will avoid costly experimental testing and reduce uncertainty in designing thermal recovery processes. First, we reviewed critically the existing literature choosing the most promising models for viscosity determination. Then, we modified an existing viscosity correlation, based on the corresponding states principle in order to fit more than two thousand commercial viscosity data. We collected data for compositional and black oil samples (absence of compositional data). The data were screened for inconsistencies resulting from experimental error. A procedure based on the monotonic increase or decrease of key variables was implemented to carry out the screening process. The modified equation was used to calculate the viscosity of several oil samples where compositional data were available. Finally, a simple procedure was proposed to calculate black oil viscosity from common experimental information such as, boiling point, API gravity and molecular weight.

  13. Viscosity dictates metabolic activity of Vibrio ruber

    PubMed Central

    Borić, Maja; Danevčič, Tjaša; Stopar, David

    2012-01-01

    Little is known about metabolic activity of bacteria, when viscosity of their environment changes. In this work, bacterial metabolic activity in media with viscosity ranging from 0.8 to 29.4 mPas was studied. Viscosities up to 2.4 mPas did not affect metabolic activity of Vibrio ruber. On the other hand, at 29.4 mPas respiration rate and total dehydrogenase activity increased 8 and 4-fold, respectively. The activity of glucose-6-phosphate dehydrogenase (GPD) increased up to 13-fold at higher viscosities. However, intensified metabolic activity did not result in faster growth rate. Increased viscosity delayed the onset as well as the duration of biosynthesis of prodigiosin. As an adaptation to viscous environment V. ruber increased metabolic flux through the pentose phosphate pathway and reduced synthesis of a secondary metabolite. In addition, V. ruber was able to modify the viscosity of its environment. PMID:22826705

  14. Viscosity of Co-B melts

    NASA Astrophysics Data System (ADS)

    Olyanina, N. V.; Bel'tyukov, A. L.; Lad'yanov, V. I.

    2016-02-01

    The temperature and concentration dependences of the kinematic viscosity of Co-B melts with a boron content up to 50 at % are studied by torsional vibrations. The viscosity polytherms are satisfactorily described by the Arrhenius equation. An increase in the viscosity with an increase in the boron content from 15 to 36 at % is observed in the concentration dependence of the viscosity. The viscosity of the melt is almost independent of the boron content in concentration ranges of 0-15 and 36-50 at %. The concentration dependence of the melt viscosity of the system is calculated using various equations. The best coincidence with the experimental data is obtained for the calculation using the Kaptay equation.

  15. Saybolt universal viscosity converted to kinematic

    SciTech Connect

    Anaya, C.; Bermudez, O.

    1987-09-21

    This article describes a program for personal and handheld computers, written in Basic, which has been developed for the conversion of Saybolt universal viscosity in Saybolt Universal Seconds (SSU or SUS) to kinematic viscosity in centistokes (cSt), at any selected temperature. It was developed using the mathematical relationship presented in the American Society for Testing and Materials (ASTM) standard D2161-82. In the standard, an equation is presented to convert kinematic viscosity to Saybolt universal viscosity, but nothing is presented to convert from Saybolt to kinematic because it is necessary to find the roots of a nonexplicit function. There are several numerical methods that can be used to determine the roots of the nonexplicit function, and therefore, convert Saybolt universal viscosity to kinematic viscosity. In the program, the first iteration of the second-order Newton-Raphson method is followed by the Wegstein method as a convergence accelerator.

  16. Shear viscosity of a model for confined granular media.

    PubMed

    Soto, Rodrigo; Risso, Dino; Brito, Ricardo

    2014-12-01

    The shear viscosity in the dilute regime of a model for confined granular matter is studied by simulations and kinetic theory. The model consists on projecting into two dimensions the motion of vibrofluidized granular matter in shallow boxes by modifying the collision rule: besides the restitution coefficient that accounts for the energy dissipation, there is a separation velocity that is added in each collision in the normal direction. The two mechanisms balance on average, producing stationary homogeneous states. Molecular dynamics simulations show that in the steady state the distribution function departs from a Maxwellian, with cumulants that remain small in the whole range of inelasticities. The shear viscosity normalized with stationary temperature presents a clear dependence with the inelasticity, taking smaller values compared to the elastic case. A Boltzmann-like equation is built and analyzed using linear response theory. It is found that the predictions show an excellent agreement with the simulations when the correct stationary distribution is used but a Maxwellian approximation fails in predicting the inelasticity dependence of the viscosity. These results confirm that transport coefficients depend strongly on the mechanisms that drive them to stationary states. PMID:25615082

  17. Shear viscosity of a model for confined granular media

    NASA Astrophysics Data System (ADS)

    Soto, Rodrigo; Risso, Dino; Brito, Ricardo

    2014-12-01

    The shear viscosity in the dilute regime of a model for confined granular matter is studied by simulations and kinetic theory. The model consists on projecting into two dimensions the motion of vibrofluidized granular matter in shallow boxes by modifying the collision rule: besides the restitution coefficient that accounts for the energy dissipation, there is a separation velocity that is added in each collision in the normal direction. The two mechanisms balance on average, producing stationary homogeneous states. Molecular dynamics simulations show that in the steady state the distribution function departs from a Maxwellian, with cumulants that remain small in the whole range of inelasticities. The shear viscosity normalized with stationary temperature presents a clear dependence with the inelasticity, taking smaller values compared to the elastic case. A Boltzmann-like equation is built and analyzed using linear response theory. It is found that the predictions show an excellent agreement with the simulations when the correct stationary distribution is used but a Maxwellian approximation fails in predicting the inelasticity dependence of the viscosity. These results confirm that transport coefficients depend strongly on the mechanisms that drive them to stationary states.

  18. Holographic viscosity of fundamental matter.

    PubMed

    Mateos, David; Myers, Robert C; Thomson, Rowan M

    2007-03-01

    A holographic dual of a finite-temperature SU(Nc) gauge theory with a small number of flavors Nfviscosity to entropy ratio in these theories saturates the conjectured universal bound eta/s> or =1/4pi. Given the known results for the entropy density, the contribution of the fundamental matter eta fund is therefore enhanced at strong 't Hooft coupling lambda; for example, eta fund approximately lambda NcNfT3 in four dimensions. Other transport coefficients are analogously enhanced. These results hold with or without a baryon number chemical potential. PMID:17358523

  19. Foamed Bulk Metallic Glass (Foam) Investigation

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This soldering iron has an evacuated copper capsule at the tip that contains a pellet of Bulk Metallic Glass (BMG) aboard the International Space Station (ISS). Prior to flight, researchers sealed a pellet of bulk metallic glass mixed with microscopic gas-generating particles into the copper ampoule under vacuum. Once heated in space, such as in this photograph, the particles generated gas and the BMG becomes a viscous liquid. The released gas made the sample foam within the capsule where each microscopic particle formed a gas-filled pore within the foam. The inset image shows the oxidation of the sample after several minutes of applying heat. Although hidden within the brass sleeve, the sample retained the foam shape when cooled, because the viscosity increased during cooling until it was solid.

  20. Viscosity undulations in the lower mantle: The dynamical role of iron spin transition

    NASA Astrophysics Data System (ADS)

    Justo, J. F.; Morra, G.; Yuen, D. A.

    2015-07-01

    A proper determination of the lower-mantle viscosity profile is fundamental to understanding Earth geodynamics. Based on results coming from different sources, several models have been proposed to constrain the variations of viscosity as a function of pressure, stress and temperature. While some models have proposed a relatively modest viscosity variation across the lower mantle, others have proposed variations of several orders of magnitude. Here, we have determined the viscosity of ferropericlase, a major mantle mineral, and explored the role of the iron high-to-low spin transition. Viscosity was described within the elastic strain energy model, in which the activation parameters are obtained from the bulk and shear wave velocities. Those velocities were computed combining first principles total energy calculations and the quasi-harmonic approximation. As a result of a strong elasticity softening across the spin transition, there is a large reduction in the activation free energies of the materials creep properties, leading to viscosity undulations. These results suggest that the variations of the viscosity across the lower mantle, resulting from geoid inversion and postglacial rebound studies, may be caused by the iron spin transition in mantle minerals. Implications of the undulated lower mantle viscosity profile exist for both, down- and up-wellings in the mantle. We find that a viscosity profile characterized by an activation free energy of G* (z0) ˜ 300- 400 kJ /mol based on diffusion creep and dilation factor δ = 0.5 better fits the observed high velocity layer at mid mantle depths, which can be explained by the stagnation and mixing of mantle material. Our model also accounts for the growth of mantle plume heads up to the size necessary to explain the Large Igneous Provinces that characterize the start of most plume tracks.

  1. From viscosity and surface tension to marangoni flow in melts

    NASA Astrophysics Data System (ADS)

    Sun, Shouyi; Zhang, Ling; Jahanshahi, Sharif

    2003-10-01

    This article covers some of our recent work on slag viscosity, the surface tension of liquid Cu-O alloys, and the relative role of Marangoni and bulk flow on refractory wear in iron-silicate slags. A viscosity model developed for slags containing SiO2, Al2O3, Fe2O3, CaO, MgO, MnO, FeO, PbO, NiO, Cu2O, ZnO, CoO, and TiO2 is capable of representing the effects of temperature, silica, and network-modifier cations within a wide range of temperatures and compositions. It forms a useful part of a computational package for multiphase-equilibrium (MPE) calculations and for predicting slag viscosities. The models are well applicable to a range of industrial slags (blast furnace, new iron making, base-metal and Platinum Group Metals (PGM) smelting, and coal-ash slags). The package has also some capability of predicting the viscosity of slags containing suspended solids. The surface tension of liquid copper-oxygen alloys has also been analyzed. The adsorption behavior of oxygen in liquid copper is well represented by the combined Langmuir-Gibbs isotherm. According to the rate data for silica-rod dissolution in liquid iron-silicate slags at 1573 K, the preferential attack at the slag line diminishes as the linear velocity of flow at the surface of the rotating silica rod reaches 9 to 16 cm/s. A tentative analysis gives the critical condition, that relates the critical Reynolds (Re) and Marangoni (Ma) number by the equation Re*2=0.13 Ma*.

  2. An Empirical Viscosity Model for Coal Slags

    SciTech Connect

    Matyas, Josef; Cooley, Scott K.; Sundaram, S. K.; Rodriguez, Carmen P.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-10-25

    Slags of low viscosity readily penetrate the refractory lining in slagging gasifiers, causing rapid and severe corrosion called spalling. In addition, a low-viscosity slag that flows down the gasifier wall forms a relatively thin layer of slag on the refractory surface, allowing the corrosive gases in the gasifier to participate in the chemical reactions between the refractory and the slag. In contrast, a slag viscosity of <25 Pa•s at 1400°C is necessary to minimize the possibility of plugging the slag tap. There is a need to predict and optimize slag viscosity so slagging gasifiers can operate continuously at temperatures ranging from 1300 to 1650°C. The approach adopted in this work was to statistically design and prepare simulated slags, measure the viscosity as a function of temperature, and develop a model to predict slag viscosity based on slag composition and temperature. Statistical design software was used to select compositions from a candidate set of all possible vertices that will optimally represent the composition space for 10 main components. A total of 21 slag compositions were generated, including 5 actual coal slag compositions. The Arrhenius equation was applied to measured viscosity versus temperature data of tested slags, and the Arrhenius coefficients (A and B in ln(vis) = A + B/T) were expressed as linear functions of the slag composition. The viscosity model was validated using 1) data splitting approach, and 2) viscosity/temperature data of selected slag compositions from the literature that were formulated and melted at Pacific Northwest National Laboratory. The capability of the model to predict the viscosity of coal slags was compared with the model developed by Browning et al. because this model can predict the viscosity of slags from coal ash better than the most commonly used empirical models found in the literature.

  3. Low shear viscosity due to Anderson localization

    SciTech Connect

    Giannakis, Ioannis; Hou Defu; Ren Haicang; Li Jiarong

    2008-01-15

    We study the Anderson localization effect on the shear viscosity in a system with random medium by Kubo formula. We show that this effect can suppress nonperturbatively the shear viscosity and other transport coefficients. The possible relevancy of such a suppression to the near perfect fluid behavior of the quark-gluon plasma created in heavy-ion collisions is discussed.

  4. Reducing blood viscosity with magnetic fields

    NASA Astrophysics Data System (ADS)

    Tao, R.; Huang, K.

    2011-07-01

    Blood viscosity is a major factor in heart disease. When blood viscosity increases, it damages blood vessels and increases the risk of heart attacks. Currently, the only method of treatment is to take drugs such as aspirin, which has, however, several unwanted side effects. Here we report our finding that blood viscosity can be reduced with magnetic fields of 1 T or above in the blood flow direction. One magnetic field pulse of 1.3 T lasting ˜1 min can reduce the blood viscosity by 20%-30%. After the exposure, in the absence of magnetic field, the blood viscosity slowly moves up, but takes a couple of hours to return to the original value. The process is repeatable. Reapplying the magnetic field reduces the blood viscosity again. By selecting the magnetic field strength and duration, we can keep the blood viscosity within the normal range. In addition, such viscosity reduction does not affect the red blood cells’ normal function. This technology has much potential for physical therapy.

  5. Plasma viscosity in inflammatory bowel disease.

    PubMed Central

    Lobo, A J; Jones, S C; Juby, L D; Axon, A T

    1992-01-01

    AIMS: To assess the relation of plasma viscosity to disease activity in patients with inflammatory bowel disease. METHODS: Crohn's disease (n = 60) and ulcerative colitis (n = 71) were diagnosed on the basis of typical histological or radiological features. Active Crohn's disease was defined as a Crohn's disease activity index of 150 or over. Active ulcerative colitis was defined as a liquid stool passed three times a day or more with blood. Blood samples were assessed for haemoglobin concentration, total white cell count, platelets, plasma viscosity, erythrocyte sedimentation rate, serum albumin, and C-reactive protein. RESULTS: Plasma viscosity was higher in those with active Crohn's disease compared with those with inactive Crohn's disease or active ulcerative colitis. Plasma viscosity correlated significantly with erythrocyte sedimentation rate, C-reactive protein, and platelet count in patients with Crohn's disease. In ulcerative colitis plasma viscosity correlated only with serum C-reactive protein. Plasma viscosity showed a low sensitivity for detecting active Crohn's disease, with 48% of those with active disease having a plasma viscosity within the laboratory reference range. CONCLUSIONS: Plasma viscosity is related to disease activity in Crohn's disease, but is insufficiently sensitive for it to replace erythrocyte sedimentation rate as a measure of the acute phase response in Crohn's disease. PMID:1740516

  6. Optical fiber-based fluorescent viscosity sensor

    NASA Astrophysics Data System (ADS)

    Haidekker, Mark A.; Akers, Walter J.; Fischer, Derek; Theodorakis, Emmanuel A.

    2006-09-01

    Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

  7. Plasma viscosity elevations with simulated weightlessness

    NASA Technical Reports Server (NTRS)

    Martin, D. G.; Convertino, V. A.; Goldwater, D.; Ferguson, E. W.; Schoomaker, E. B.

    1986-01-01

    A hypothesis correlating an increase in blood viscosity during bed rest to a decrease in aerobic capacity during simulated weightlessness is tested. Eight human subjects were studied on the sixth day of bed rest during two consecutive 10-d bed rest periods separated by a 14-d recovery interval designed to simulate the flight-layover schedule of Shuttle astronauts. Plasma viscosity and volume were measured, together with maximal aerobic capacity (VO2max). An increase in hematocrit, plasma protein, and fibrinogen concentrations was found, contributing to an elevation in plasma viscosity. VO2max decreased significantly in the first, but not the second bed rest cycle, and though many individuals exhibited a decrease in plasma volume and aerobic capacity coupled with elevated plasma viscosity, correlations between these variables were lacking. It is concluded that the decrease in VO2max observed following simulated weightlessness cannot be attributed to alterations in muscle blood flow resulting from increased blood viscosity.

  8. Puna Dacite: Likely Temperature, Viscosity, Origin, Size, and Parent Body Nature

    NASA Astrophysics Data System (ADS)

    Marsh, B.; Teplow, W.; Reagan, M.; Sims, K.

    2008-12-01

    This is very likely the first accidental encounter of an in situ live magma within Earth. The importance of this occurrence to the possible ongoing interrogation of an active, docile magma cannot be overemphasized. Here we report on inferences on the nature of the magma and its relation to a parent basaltic body. The Glass: In oil the glass is colorless with 5-8 % euhedral, nonquench crystals of plagioclase, Fe-Ti oxide, orthopyroxene, and apatite. There is no vesiculation and the glass is unstructured except for patches of perhaps incipient spherulite and swirls, which may reflect drilling shear and quenching. Temperature: The temperature is inferred first using the bulk glass composition and matching the visually estimated crystallinity to that computed by MELTS, giving a temperature of 1050 C. Second, from a likely basaltic parent composition (1955 basalt) and matching the glass composition to the residual melt from protracted crystallization in MELTS, also gives a temperature of 1050 C. Comparing the dacite to the observed compositions of interstitial melts from the lava lakes, suggests a slightly higher temperature of 1065 C, reflecting the different parent basalt. One atm melting experiments confirm the former T. Magma Viscosity: The flow up the drill hole (25.88 cm diameter) can be used to estimate viscosity by calculating the time necessary for melt of a given viscosity to flow under a given pressure gradient a given distance up the drill hole. The melt flowed upward approximately 5.5.m in a few minutes. The most elusive part of the calculation involves estimating the pressure gradient driving the flow. The lithostatic load based on the depth (~2.54 km) is about 0.65 kb, which is assumed to act over a characteristic distance of about 2 m (lens size) to give a characteristic pressure gradient. Pipe flow yields a characteristic viscosity of 3.8 x 107 p. An independent calculation from MELTS using only melt composition, temperature, water content (zero), and

  9. Eruptive viscosity and volcano morphology

    NASA Technical Reports Server (NTRS)

    Posin, Seth B.; Greeley, Ronald

    1988-01-01

    Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology.

  10. Structural rejuvenation in bulk metallic glasses

    DOE PAGESBeta

    Tong, Yang; Iwashita, T.; Dmowski, Wojciech; Bei, Hongbin; Yokoyama, Y.; Egami, Takeshi

    2015-01-05

    Using high-energy X-ray diffraction we study structural changes in bulk metallic glasses after uniaxial compressive homogeneous deformation at temperatures slightly below the glass transition. We observe that deformation results in structural disordering corresponding to an increase in the fictive, or effective, temperature. However, the structural disordering saturates after yielding. Lastly, examination of the experimental structure and molecular dynamics simulation suggests that local changes in the atomic connectivity network are the main driving force of the structural rejuvenation.

  11. Physically consistent viscosity of polyphase rocks: a new method and its validation

    NASA Astrophysics Data System (ADS)

    Huet, B.; Yamato, P.; Grasemann, B.

    2012-04-01

    Metamorphic reactions constitute one of the major processes inducing strain localisation and influencing the strength of the lithosphere. However, this process has seldom been explicitly taken into account in large-scale thermomechanical models so far. Such a development requires the calculation of the strength of any rock knowing its mineralogical composition and the strength of its components. Most of the existing polyphase rocks strength models are empirical. Those that are physically consistent provide strength bounds and/or lead to long and complex calculations, which is not suitable for large scale modelling. Here, we present a new method to calculate the bulk viscosity of a polyphase rock knowing the fraction and the creep parameters of each phase constituting the rock. This analytical method uses a minimization procedure of the power dissipated in the polyphase rock with the Lagrange multiplier technique. This method is simple and quickly leads to values of the bulk viscosity as well as partitioning of stress and strain rate between phases. It allows us to revaluate the classical bounds and to compute a close approximate of bulk viscosity and bulk creep parameters, that are physically consistent. Then, this method is tested and validated against experimental data and numerical models under simple shear condition. Finally, we present an application of this method to the evolution of strength in a subducting slab.

  12. Universal Quantum Viscosity in a Unitary Fermi Gas

    NASA Astrophysics Data System (ADS)

    Cao, Chenglin

    shear viscosity is directly related to the damping rate of an oscillating cloud, through the same universal hydrodynamic equations. The raw data from the previously measured radial breathing experiments are carefully analyzed to extract the shear viscosity. The low temperature data join with the high temperature data smoothly, which presents the full measurement of the quantum shear viscosity from nearly the ground state to the two-body Boltzmann regime. The possible effects of the bulk viscosity in the high temperature anisotropic expansion experiment is also studied and found to be consistent with the predicted vanishing bulk viscosity in the normal fluid phase at unitarity. Using the measured shear viscosity eta and the previously measured entropy density s, the ratio of eta/s is estimated and therefore compared to a string theory limit, which conjectures eta/ s ≥ h/4pikB for any fluid and defines a perfect fluid when the equality is satisfied. It is found that eta/s, for a unitary Fermi gas at the normal-superfluid transition point, is about 5 times the string limit. This shows that our unitary Fermi gas exhibit nearly perfect fluidity at low temperatures. In addition to the quantum shear viscosity measurement, consistent and accurate methods of calibrating the energy and temperature for unitary Fermi gases is also developed in this thesis. While the energy is calculated from the cloud dimensions by exploiting the virial theorem, the temperature is determined using different methods for different temperature regimes. At high temperatures, the second virial coefficient approximation is applied to the energy density, from which a variety of thermodynamic quantities, including the temperature, are derived. For the low temperatures, the previous calibration from the energy E and entropy S measurement is improved by using a better calculation on the entropy and adding more constraints at higher temperatures using the second virial approximation. A power law curve with

  13. Dementia and driving

    MedlinePlus

    ... not drive at times of the day when traffic is heaviest. Do not drive when the weather is bad. Do not drive long distances. Drive only on roads the person is used to. Caregivers should try to lessen ...

  14. Viscosity measurement techniques in Dissipative Particle Dynamics

    NASA Astrophysics Data System (ADS)

    Boromand, Arman; Jamali, Safa; Maia, Joao M.

    2015-11-01

    In this study two main groups of viscosity measurement techniques are used to measure the viscosity of a simple fluid using Dissipative Particle Dynamics, DPD. In the first method, a microscopic definition of the pressure tensor is used in equilibrium and out of equilibrium to measure the zero-shear viscosity and shear viscosity, respectively. In the second method, a periodic Poiseuille flow and start-up transient shear flow is used and the shear viscosity is obtained from the velocity profiles by a numerical fitting procedure. Using the standard Lees-Edward boundary condition for DPD will result in incorrect velocity profiles at high values of the dissipative parameter. Although this issue was partially addressed in Chatterjee (2007), in this work we present further modifications (Lagrangian approach) to the original LE boundary condition (Eulerian approach) that will fix the deviation from the desired shear rate at high values of the dissipative parameter and decrease the noise to signal ratios in stress measurement while increases the accessible low shear rate window. Also, the thermostat effect of the dissipative and random forces is coupled to the dynamic response of the system and affects the transport properties like the viscosity and diffusion coefficient. We investigated thoroughly the dependency of viscosity measured by both Eulerian and Lagrangian methodologies, as well as numerical fitting procedures and found that all the methods are in quantitative agreement.

  15. Viscosity of multicomponent partially ionized gas mixtures

    NASA Astrophysics Data System (ADS)

    Armaly, B. F.; Sutton, K.

    1980-07-01

    An approximate method is proposed for predicting the viscosity of partially ionized gas mixtures. This technique expresses the viscosity of a mixture in terms of the viscosities of the individual pure components, is simple in form, and does not require large computer run times or storage. Thus, the technique is suitable for use with complex flowfields and heat-transfer calculations. Results for gas mixtures which are representative of the atmospheres of Jupiter, Earth, and Venus, are presented and it is shown that the results compare favorably with detailed kinetic-theory analyses.

  16. Viscoseal performance with rarefied-gas sealant

    NASA Technical Reports Server (NTRS)

    Milligan, M. W.

    1971-01-01

    A fundamental study of viscoseals having a rarefied gas as the sealant has been conducted. Both experimental and analytical investigations are reported. Three different analytical models have been formulated and are described in detail. An experimental investigation has been conducted on multiple grooved two-inch diameter viscoseals over a wide range of gas densities and shaft speeds up to 30,000 rpm. Comparisons are presented between actual viscoseal performance and the theoretical predictions for both sealing coefficient and net leakage parameters as functions of the degree of gas rarefication. Recommendations are presented for the use of the analytical models.

  17. Viscosity of high-temperature iodine

    NASA Technical Reports Server (NTRS)

    Kang, Steve H.; Kunc, Joseph A.

    1991-01-01

    The viscosity coefficient of iodine in the temperature range 500 - 3000 K is calculated. Because of the low dissociation energy of the I2 molecules, the dissociation degree of the gas increases quickly with temperature, and I + I2 and I + I collisions must be taken into account in calculation of viscosity at temperatures greater than 1000 deg. Several possible channels for atom-atom interaction are considered, and the resulting collision integrals are averaged over all the important channels. It is also shown that the rigid-sphere model is inaccurate in predictions of the viscosity.

  18. Free Volume in Membranes: Viscosity or Tension?

    PubMed Central

    Markin, V. S.; Sachs, F.

    2016-01-01

    Many papers have used fluorescent probe diffusion to infer membrane viscosity but the measurement is actually an assay of the free volume of the membrane. The free volume is also related to the membrane tension. Thus, changes in probe mobility refer equally well to changes in membrane tension. In complicated structures like cell membranes, it appears more intuitive to consider variations in free volume as referring to the effect of domains structures and interactions with the cytoskeleton than changes in viscosity since tension is a state variable and viscosity is not.

  19. Viscoseal performance with rarefied-gas sealant

    NASA Technical Reports Server (NTRS)

    Milligan, M. W.

    1973-01-01

    A fundamental study of viscoseals having a rarefied gas as the sealant was conducted. Both experimental and analytical investigations are reported. Three different analytical models were formulated and are described in detail. An experimental investigation was conducted on multiple grooved two-inch diameter viscoseals over a wide range of gas densities and shaft speeds up to 30,000 rpm. Comparisons are presented between actual viscoseal performance and the theoretical predictions for both sealing coefficient and net leakage parameters as functions of the degree of gas rarefication. Recommendations are presented for the use of the analytical models.

  20. Shear viscosity in the postquasistatic approximation

    SciTech Connect

    Peralta, C.; Rosales, L.; Rodriguez-Mueller, B.; Barreto, W.

    2010-05-15

    We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of anisotropic nonadiabatic radiating and dissipative distributions in general relativity. Dissipation is described by viscosity and free-streaming radiation, assuming an equation of state to model anisotropy induced by the shear viscosity. We match the interior solution, in noncomoving coordinates, with the Vaidya exterior solution. Two simple models are presented, based on the Schwarzschild and Tolman VI solutions, in the nonadiabatic and adiabatic limit. In both cases, the eventual collapse or expansion of the distribution is mainly controlled by the anisotropy induced by the viscosity.

  1. Viscosity studies of water based magnetite nanofluids

    NASA Astrophysics Data System (ADS)

    Anu, K.; Hemalatha, J.

    2016-05-01

    Magnetite nanofluids of various concentrations have been synthesized through co-precipitation method. The structural and topographical studies made with the X-Ray Diffractometer and Atomic Force Microscope are presented in this paper. The density and viscosity studies for the ferrofluids of various concentrations have been made at room temperature. The experimental viscosities are compared with theoretical values obtained from Einstein, Batchelor and Wang models. An attempt to modify the Rosensweig model is made and the modified Rosensweig equation is reported. In addition, new empirical correlation is also proposed for predicting viscosity of ferrofluid at various concentrations.

  2. Shear viscosity in magnetized neutron star crust

    NASA Astrophysics Data System (ADS)

    Ofengeim, D. D.; Yakovlev, D. G.

    2015-12-01

    The electron shear viscosity due to Coulomb scattering of degenerate electrons by atomic nuclei throughout a magnetized neutron star crust is calculated. The theory is based on the shear viscosity coefficient calculated neglecting magnetic fields but taking into account gaseous, liquid and solid states of atomic nuclei, multiphonon scattering processes, and finite sizes of the nuclei albeit neglecting the effects of electron band structure. The effects of strong magnetic fields are included in the relaxation time approximation with the effective electron relaxation time taken from the field-free theory. The viscosity in a magnetized matter is described by five shear viscosity coefficients. They are calculated and their dependence on the magnetic field and other parameters of dense matter is analyzed. Possible applications and open problems are outlined.

  3. Viscosity of Sheared Helical filament Suspensions

    NASA Astrophysics Data System (ADS)

    Sartucci, Matthew; Urbach, Jeff; Blair, Dan; Schwenger, Walter

    The viscosity of suspensions can be dramatically affected by high aspect ratio particles. Understanding these systems provides insight into key biological functions and can be manipulated for many technological applications. In this talk, the viscosity as a function of shear rate of suspensions of helical filaments is compared to that of suspensions of straight rod-like filaments. Our goal is to determine the impact of filament geometry on low volume fraction colloidal suspensions in order to identify strategies for altering viscosity with minimal volume fraction. In this research, the detached flagella of the bacteria Salmonella Typhimurium are used as a model system of helical filaments and compared to mutated straight flagella of the Salmonella. We compare rheological measurements of the suspension viscosity in response to shear flow and use a combination of the rheology and fluorescence microscopy to identify the microstructural changes responsible for the observed rheological response.

  4. Sludge based Bacillus thuringiensis biopesticides: viscosity impacts.

    PubMed

    Brar, S K; Verma, M; Tyagi, R D; Valéro, J R; Surampalli, R Y

    2005-08-01

    Viscosity studies were performed on raw, pre-treated (sterilised and thermal alkaline hydrolysed or both types of treatment) and Bacillus thuringiensis (Bt) fermented sludges at different solids concentration (10-40 g/L) for production of biopesticides. Correlations were established among rheological parameter (viscosity), solids (total and dissolved) concentration and entomotoxicity (Tx) of Bt fermented sludges. Exponential and power laws were preferentially followed by hydrolysed fermented compared to raw fermented sludge. Soluble chemical oxygen demand variation corroborated with increase in dissolved solids concentration on pre-treatments, contributing to changes in viscosity. Moreover, Tx was higher for hydrolysed fermented sludge in comparison to raw fermented sludge owing to increased availability of nutrients and lower viscosity that improved oxygen transfer. The shake flask results were reproducible in fermenter. This study will have major impact on selecting fermentation, harvesting and formulation techniques of Bt fermented sludges for biopesticide production. PMID:15979118

  5. Second coefficient of viscosity in air

    NASA Technical Reports Server (NTRS)

    Ash, Robert L.; Zuckerwar, Allan J.; Zheng, Zhonquan

    1991-01-01

    Acoustic attenuation measurements in air were analyzed in order to estimate the second coefficient of viscosity. Data over a temperature range of 11 C to 50 C and at relative humidities between 6 percent and 91 percent were used. This analysis showed that the second coefficient of viscosity varied between 1900 and 20,000 times larger than the dynamic or first coefficient of viscosity over the temperature and humidity range of the data. In addition, the data showed that the molecular relaxation effects, which are responsible for the magnitude of the second coefficient of viscosity, place severe limits on the use of time-independent, thermodynamic equations of state. Compressible flows containing large streamwise velocity gradients, like shock waves, which cause significant changes in particle properties to occur during time intervals shorter than hundredths of seconds, must be modeled using dynamic equations of state. The dynamic model approach is described briefly.

  6. Quartz resonator fluid density and viscosity monitor

    DOEpatents

    Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.

    1998-01-01

    A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

  7. Measurement of DWPF glass viscosity - Final Report

    SciTech Connect

    Harbour, J.R.

    2000-02-17

    This report details the results of a scoping study funded by the Defense Waste Processing Facility (DWPF) for the measurement of melt viscosities for simulated glasses representative of Macrobatch 2 (Tank 42/51 feed).

  8. Eddy viscosity measurements in a rectangular jet

    NASA Technical Reports Server (NTRS)

    Swan, David H.; Morrison, Gerald L.

    1988-01-01

    The flow field of a rectangular jet with a 2:1 aspect ratio was studied at a Reynolds number of 100,000 (Mach number 0.09) using three-dimensional laser Doppler velocimetry (LDV). Velocity gradients, Reynolds stress tensor components, and scalar eddy viscosities are presented for the major and minor axis planes of the jet. The eddy viscosity model was found to be applicable only in the direction of maximum mean velocity gradient.

  9. A Simple BODIPY-Based Viscosity Probe for Imaging of Cellular Viscosity in Live Cells.

    PubMed

    Su, Dongdong; Teoh, Chai Lean; Gao, Nengyue; Xu, Qing-Hua; Chang, Young-Tae

    2016-01-01

    Intracellular viscosity is a fundamental physical parameter that indicates the functioning of cells. In this work, we developed a simple boron-dipyrromethene (BODIPY)-based probe, BTV, for cellular mitochondria viscosity imaging by coupling a simple BODIPY rotor with a mitochondria-targeting unit. The BTV exhibited a significant fluorescence intensity enhancement of more than 100-fold as the solvent viscosity increased. Also, the probe showed a direct linear relationship between the fluorescence lifetime and the media viscosity, which makes it possible to trace the change of the medium viscosity. Furthermore, it was demonstrated that BTV could achieve practical applicability in the monitoring of mitochondrial viscosity changes in live cells through fluorescence lifetime imaging microscopy (FLIM). PMID:27589762

  10. Macroscopic and direct light propulsion of bulk graphene material

    NASA Astrophysics Data System (ADS)

    Zhang, Tengfei; Chang, Huicong; Wu, Yingpeng; Xiao, Peishuang; Yi, Ningbo; Lu, Yanhong; Ma, Yanfeng; Huang, Yi; Zhao, Kai; Yan, Xiao-Qing; Liu, Zhi-Bo; Tian, Jian-Guo; Chen, Yongsheng

    2015-07-01

    It has been a great challenge to achieve the direct light manipulation of matter on a bulk scale. In this work the direct light propulsion of matter is observed on a macroscopic scale using a bulk graphene-based material. The unique structure and properties of graphene, and the novel morphology of the bulk three-dimensional linked graphene material make it capable not only of absorbing light at various wavelengths but also of emitting energetic electrons efficiently enough to drive the bulk material, following Newtonian mechanics. Thus, the unique photonic and electronic properties of individual graphene sheets are manifested in the response of the bulk state. These results offer an exciting opportunity to bring about bulk-scale light manipulation with the potential to realize long-sought applications in areas such as the solar sail and space transportation driven directly by sunlight.

  11. Length-Scale Dependent Viscosity in Semidilute Polyelectrolyte Solutions

    NASA Astrophysics Data System (ADS)

    Poling-Skutvik, Ryan; Krishnamoorti, Ramanan; Conrad, Jacinta

    2015-03-01

    Using optical microscopy and particle tracking algorithms, we measured the mean-squared displacements (MSDs) of fluorescent polystyrene particles with diameters ranging from 300 nm to 2 μm suspended in semidilute solutions of high molecular weight partially hydrolyzed polyacrylamide. The solutions had polymer concentrations ranging from 0.67 to 67c*, where c* is the overlap concentration, and estimated correlation lengths of ~ 100 to 900 nm. At short times, the particles exhibited subdiffusive behavior characterized by MSD ~tα with α < 1 . On long time scales, the particles transitioned to Fickian diffusion (α = 1) and their diffusivity was calculated from the slope of the MSD. Whereas the large particles agreed with predictions using the Stokes-Einstein equation and bulk zero-shear viscosity, the smaller particles diffused much faster than predicted. The relative diffusivities do not collapse onto a single curve, but rather form a continuum that varies with particle size. This indicates that the particles experience a size-dependent effective viscosity mediated by the ratio of particle diameter to characteristic length scales in the polymer solution.

  12. The role of crystallinity and viscosity in the formation of submarine lava flow morphology

    NASA Astrophysics Data System (ADS)

    McClinton, J. Timothy; White, Scott M.; Colman, Alice; Rubin, Kenneth H.; Sinton, John M.

    2014-09-01

    Submarine lava flow morphology is commonly used to estimate relative flow velocity, but the effects of crystallinity and viscosity are rarely considered. We use digital petrography and quantitative textural analysis techniques to determine the crystallinity of submarine basaltic lava flows, using a set of samples from previously mapped lava flow fields at the hotspot-affected Galápagos Spreading Center. Crystallinity measurements were incorporated into predictive models of suspension rheology to characterize lava flow consistency and rheology. Petrologic data were integrated to estimate bulk lava viscosity. We compared the crystallinity and viscosity of each sample with its flow morphology to determine their respective roles in submarine lava emplacement dynamics. We find no correlation between crystallinity, bulk viscosity, and lava morphology, implying that flow advance rate is the primary control on submarine lava morphology. However, we show systematic variations in crystal size and shape distribution among pillows, lobates, and sheets, suggesting that these parameters are important indicators of eruption processes. Finally, we compared the characteristics of lavas from two different sampling sites with contrasting long-term magma supply rates. Differences between lavas from each study site illustrate the significant effect of magma supply on the physical properties of the oceanic upper crust.

  13. Oral sensory discrimination of fluid viscosity.

    PubMed

    Smith, C H; Logemann, J A; Burghardt, W R; Carrell, T D; Zecker, S G

    1997-01-01

    This study was designed to investigate the ability of normal young adult volunteers to sensorially identify Newtonian fluids of specified viscosities. Twenty subjects, 10 men and 10 women between the ages of 18 and 29 years participated. Seven stimuli, consisting of combinations of corn syrup and water, with viscosities ranging from 2 to 2,240 centipoise (cP) were prepared and characterized using a coaxial rotational viscometer. Subjects were presented with two anchor stimuli representing the extremes of the range of viscosities as a basis from which the experimental stimuli were judged. The seven experimental stimuli were randomly presented to each subject 10 times. The accuracy with which the subjects identified the viscosity of the fluid was significant at p < 0.01. The pattern of response was not significantly different across subjects nor gender. There were no differences in performance throughout the duration of the study. The repeat presentation of the anchor points did not significantly affect performance. Further research on oral perception of viscosity, and the processes that mediate changes in swallow physiology resulting from changes in viscosity is required. PMID:9071805

  14. The viscosity of short polyelectrolyte solutions.

    PubMed

    Izzo, Dora; Cloitre, Michel; Leibler, Ludwik

    2014-03-21

    We consider the viscosity of solutions of highly charged short polyelectrolytes. Our system is a poly(styrene-maleic acid) copolymer solution (SMA) with various added salt concentrations in dilute and semidilute regimes. The SMA solutions show some particular features: (i) variations of the specific viscosity measured for different values of concentration and ionic strength can be rescaled on two universal curves when plotted as a function of the effective volume fraction; (ii) the reduced viscosity is proportional to the Debye length. In order to describe the viscosity of such a system we model the motion of the charged rods considering a simpler system: we replace each charged rod and its corresponding charge cloud by an effective neutral rod. This modified system is yet below the concentrated regime and, at most, steric interactions are left. In the semidilute regime, we model the rescaled rods moving under a mean field potential and obtain a dynamical equation for the orientational tensor, considered small, and the viscosity is derived from it. Within our mean field approach, the effects due to the rod Brownian motion and due to the potential cancel each other and the behavior of the viscosity is explained in terms of the effective volume fraction only. Our predictions are in good qualitative agreement with the experimental results over a wide range of parameters, and suggest a method for obtaining the rotational diffusion constant in the semidilute regime. PMID:24652236

  15. High-Temperature Viscosity of Commercial Glasses

    SciTech Connect

    Hrma, Pavel R.

    2006-08-31

    Arrhenius models were developed for glass viscosity within the processing temperature of six types of commercial glasses: low-expansion-borosilicate glasses, E glasses, fiberglass wool glasses, TV panel glasses, container glasses, and float glasses. Both local models (for each of the six glass types) and a global model (for the composition region of commercial glasses, i.e., the six glass types taken together) are presented. The models are based on viscosity data previously obtained with rotating spindle viscometers within the temperature range between 900 C and 1550 C; the viscosity varied from 1 Pa?s to 750 Pa?s. First-order models were applied to relate Arrhenius coefficients to the mass fractions of 15 components: SiO2, TiO2, ZrO2, Al2O3, Fe2O3, B2O3, MgO, CaO, SrO, BaO, PbO, ZnO, Li2O, Na2O, K2O. The R2 is 0.98 for the global model and ranges from .097 to 0.99 for the six local models. The models are recommended for glasses containing 42 to 84 mass% SiO2 to estimate viscosities or temperatures at a constant viscosity for melts within both the temperature range from 1100 C to 1550 C and viscosity range from 5 to 400 Pa?s.

  16. High-Temperature Viscosity Of Commercial Glasses

    SciTech Connect

    Hrma, Pavel R; See, Clem A; Lam, Oanh P; Minister, Kevin B

    2005-01-01

    Viscosity was measured for six types of commercial glasses: low-expansion-borosilicate glasses, E glasses, fiberglass wool glasses, TV panel glasses, container glasses, and float glasses. Viscosity data were obtained with rotating spindle viscometers within the temperature range between 900°C and 1550°C; the viscosity varied from 1 Pa∙s to 750 Pa∙s. Arrhenius coefficients were calculated for individual glasses and linear models were applied to relate them to the mass fractions of 11 major components (SiO2, CaO, Na2O, Al2O3, B2O3, BaO, SrO, K2O, MgO, PbO, and ZrO2) and 12 minor components (Fe2O3, ZnO, Li2O, TiO2, CeO2, F, Sb2O3, Cr2O3, As2O3, MnO2, SO3, and Co3O4). The models are recommended for glasses containing 42 to 84 mass% SiO2 to estimate viscosities or temperatures at a constant viscosity for melts within both the temperature range from 1100°C to 1550°C and viscosity range from 10 to 400 Pas.

  17. Viscosity of peridotite liquid up to 13 GPa: Implications for magma ocean viscosities [rapid communication

    NASA Astrophysics Data System (ADS)

    Liebske, Christian; Schmickler, Bettina; Terasaki, Hidenori; Poe, Brent T.; Suzuki, Akio; Funakoshi, Ken-ichi; Ando, Ryota; Rubie, David C.

    2005-12-01

    The viscosity of synthetic peridotite liquid has been investigated at high pressures using in-situ falling sphere viscometry by combining a multi-anvil technique with synchrotron radiation. We used a newly designed capsule containing a small recessed reservoir outside of the hot spot of the heater, in which a viscosity marker sphere is embedded in a forsterite + enstatite mixture having a higher solidus temperature than the peridotite. This experimental setup prevents spheres from falling before a stable temperature above the liquidus is established and thus avoids difficulties in evaluating viscosities from velocities of spheres falling through a partially molten sample. Experiments have been performed between 2.8 and 13 GPa at temperatures ranging from 2043 to 2523 K. Measured viscosities range from 0.019 (± 0.004) to 0.13 (± 0.02) Pa s. At constant temperature, viscosity increases with increasing pressure up to ˜ 8.5 GPa but then decreases between ˜ 8.5 and 13 GPa. The change in the pressure dependence of viscosity is likely associated with structural changes of the liquid that occur upon compression. By combining our results with recently published 0.1 MPa peridotite liquid viscosities [D.B. Dingwell, C. Courtial, D. Giordano, A. Nichols, Viscosity of peridotite liquid, Earth Planet. Sci. Lett. 226 (2004) 127-138.], the experimental data can be described by a non-Arrhenian, empirical Vogel-Fulcher-Tamman equation, which has been modified by adding a term to account for the observed pressure dependence of viscosity. This equation reproduces measured viscosities to within 0.08 log 10-units on average. We use this model to calculate viscosities of a peridotitic magma ocean along a liquid adiabat to a depth of ˜ 400 km and discuss possible effects on viscosity at greater pressures and temperatures than experimentally investigated.

  18. Viscosity and stress autocorrelation function in supercooled water: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Guo, Guang-Jun; Zhang, Yi-Gang; Refson, Keith; Zhao, Ya-Juan

    Following GUO, G.-J., and ZHANG, Y.-G., 2001, Molec. Phys. , 99 , 283, which calculates the bulk and shear viscosities of SPC/E water at 30°C and 0.999gcm -3 , further molecular dynamics simulations have been performed at state points of 0°C,-20°C,-40°C, and -60°C along an approximate isobar with the previous state point. SACF and BACF (stress autocorrelation functions related to shear and bulk viscosities, respectively) of high precision have been obtained and compared for their similarities and differences. Shear and bulk viscosities calculated from them showed an increased deviation from real water with decreasing temperature. These correlation functions were then fitted using a uniform two-step relaxation function including a fast oscillatory Kohlrausch law and a slow straightforward Kohlrausch law. The fitting parameters of SACF and BACF have been analysed in detail, and several interesting dynamic phenomena were observed. (1) The oscillation frequency of SACF (44 ~ 48ps -1 ) for short time intervals agrees with the stretching mode of hydrogen bonds, while that of BACF (7 ~ 12ps -1 ) agrees with the bending mode of hydrogen bonds. (2) With decreasing temperature, the slow relaxation fraction of the BACF increases, while that of the SACF remains constant. (3) The exponents βin the Kohlrausch laws with values greater than 1 are obtained for BACF at ambient temperatures. (4) With regard to both shear and bulk viscosities, the slow relaxation time largely increases with decreasing temperature, while the fast relaxation time slightly decreases. These phenomena are qualitatively explained and discussed.

  19. Bifurcation of magnetic island saturation controlled by plasma viscosity

    NASA Astrophysics Data System (ADS)

    Maget, P.; Février, O.; Lütjens, H.; Luciani, J.-F.; Garbet, X.

    2016-05-01

    Two nonlinear regimes, depending on the magnetic Prandtl number Prm, are identified for the magnetic islands described by resistive MHD equations. The frontier between these two regimes is sharp, and has the characteristics of a phase transition controlled by plasma viscosity. In the low Prm regime, a new form of the so-called flip instability, consisting of a sudden change in the island phase, is identified. Already known in the context of the forcing by external magnetic perturbations and localized current drive, it occurs spontaneously at low Prm. The main characteristics of this new structural instability are described. The low Prm regime is well described by the slab visco-resistive model in the linear phase, and is characterized by both a large saturation of the island and strong nonlinearly driven zonal flows (that do not significantly impact the island dynamics, however), while curvature physics strongly impacts the viscous regime.

  20. Magnetostrictive Roller-Drive Stepping Motor

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1993-01-01

    Proposed motor based on magnetostrictive effect provides stepped angular motion with angular increments of order of 100 microradians. Driven to repeat stepping cycle rapidly enough to achieve maximum speed of about 20 rpm, provides torque an order of magnitude greater than electric motors, and brakes itself when power turned off. Magnetostrictive rods in electromagnet coils push against drive plate, causing it to rotate slightly. This slight rotation jams conical rollers between cam surfaces on outer drive ring and split drum, so rollers transmit rotation to drum. Suitable for precise, high-torque, fail-safe-braking, direct drive of robot joint, without bulk and weight of additional brake mechanism and gear train.

  1. Effective viscosity of bacterial suspensions: a three-dimensional PDE model with stochastic torque.

    SciTech Connect

    Haines, B. M.; Aranson, I. S.; Berlyand, L.; Karpeev, D. A.

    2012-01-01

    We present a PDE model for dilute suspensions of swimming bacteria in a three-dimensional Stokesian fluid. This model is used to calculate the statistically-stationary bulk deviatoric stress and effective viscosity of the suspension from the microscopic details of the interaction of an elongated body with the background flow. A bacterium is modeled as an impenetrable prolate spheroid with self-propulsion provided by a point force, which appears in the model as an inhomogeneous delta function in the PDE. The bacterium is also subject to a stochastic torque in order to model tumbling (random reorientation). Due to a bacterium's asymmetric shape, interactions with prescribed generic planar background flows, such as a pure straining or planar shear flow, cause the bacterium to preferentially align in certain directions. Due to the stochastic torque, the steady-state distribution of orientations is unique for a given background flow. Under this distribution of orientations, self-propulsion produces a reduction in the effective viscosity. For sufficiently weak background flows, the effect of self-propulsion on the effective viscosity dominates all other contributions, leading to an effective viscosity of the suspension that is lower than the viscosity of the ambient fluid. This is in qualitative agreement with recent experiments on suspensions of Bacillus subtilis.

  2. Viscosity of Xenon Examined in Microgravity

    NASA Technical Reports Server (NTRS)

    Zimmerli, Gregory A.; Berg, Robert F.; Moldover, Michael R.

    1999-01-01

    Why does water flow faster than honey? The short answer, that honey has a greater viscosity, merely rephrases the question. The fundamental answer is that viscosity originates in the interactions between a fluid s molecules. These interactions are so complicated that, except for low-density gases, the viscosity of a fluid cannot be accurately predicted. Progress in understanding viscosity has been made by studying moderately dense gases and, more recently, fluids near the critical point. Modern theories predict a universal behavior for all pure fluids near the liquid-vapor critical point, and they relate the increase in viscosity to spontaneous fluctuations in density near this point. The Critical Viscosity of Xenon (CVX) experiment tested these theories with unprecedented precision when it flew aboard the Space Shuttle Discovery (STS-85) in August 1997. Near the critical point, xenon is a billion times more compressible than water, yet it has about the same density. Because the fluid is so "soft," it collapses under its own weight when exposed to the force of Earth s gravity - much like a very soft spring. Because the CVX experiment is conducted in microgravity, it achieves a very uniform fluid density even very close to the critical point. At the heart of the CVX experiment is a novel viscometer built around a small nickel screen. An oscillating electric field forces the screen to oscillate between pairs of electrodes. Viscosity, which dampens the oscillations, can be calculated by measuring the screen motion and the force applied to the screen. So that the fluid s delicate state near the critical point will not be disrupted, the screen oscillations are set to be both slow and small.

  3. On the similarity of variable viscosity flows

    NASA Astrophysics Data System (ADS)

    Voivenel, L.; Danaila, L.; Varea, E.; Renou, B.; Cazalens, M.

    2016-08-01

    Turbulent mixing is ubiquitous in both nature and industrial applications. Most of them concern different fluids, therefore with variable physical properties (density and/or viscosity). The focus here is on variable viscosity flows and mixing, involving density-matched fluids. The issue is whether or not these flows may be self-similar, or self-preserving. The importance of this question stands on the predictability of these flows; self-similar dynamical systems are easier tractable from an analytical viewpoint. More specifically, self-similar analysis is applied to the scale-by-scale energy transport equations, which represent the transport of energy at each scale and each point of the flow. Scale-by-scale energy budget equations are developed for inhomogeneous and anisotropic flows, in which the viscosity varies as a result of heterogeneous mixture or temperature variations. Additional terms are highlighted, accounting for the viscosity gradients, or fluctuations. These terms are present at both small and large scales, thus rectifying the common belief that viscosity is a small-scale quantity. Scale-by-scale energy budget equations are then adapted for the particular case of a round jet evolving in a more viscous host fluid. It is further shown that the condition of self-preservation is not necessarily satisfied in variable-viscosity jets. Indeed, the jet momentum conservation, as well as the constancy of the Reynolds number in the central region of the jet, cannot be satisfied simultaneously. This points to the necessity of considering less stringent conditions (with respect to classical, single-fluid jets) when analytically tackling these flows and reinforces the idea that viscosity variations must be accounted for when modelling these flows.

  4. Estimating Heavy Oil Viscosity from Seismic Data

    NASA Astrophysics Data System (ADS)

    Vasheghani Farahani, Fereidoon

    Heavy oils are viscoelastic material; therefore, their shear properties influence the seismic response and should not be ignored. Heavy oil viscosity, among other parameters, controls the attenuation of seismic waves which is measured in terms of quality factor Q. BISQ, a poroviscoelastic model that couples the effects of simultaneous Biot and squirt flow mechanisms, is used to relate Q to the fluid viscosity. The variation of quality factor with respect to fluid viscosity, as predicted by BISQ, matches the laboratory measurements. Quality factor is a measurable seismic attribute. Higher frequency data are more favourable for Q estimation. Crosswell seismic data from a heavy oil reservoir is used for estimating Q. Travel time tomography followed by attenuation tomography yields the quality factor. The resultingQ tomogram can be converted into the viscosity tomogram if the remaining reservoir parameters are known. Such parameters are populated for the zone of interest using the geostatistical methods from the available log and core data at borehole locations. Existing BISQ equations can only take one fluid phase into account. However, the porous reservoir rock is saturated with bitumen and water. A slightly modified version of the BISQ relations is used in order to accommodate the presence of a second fluid phase. The estimated viscosity tomogram shows ambiguity because for every given quality factor, more than one viscosity value can be calculated. Despite the ambiguity, the methodology introduced in this study demonstrates that seismic data have the potential to be used for estimation of fluid viscosity in heavy oil reservoirs, although further research is needed to improve the workflow.

  5. Transport coefficients of bulk viscous pressure in the 14-moment approximation

    NASA Astrophysics Data System (ADS)

    Denicol, G. S.; Jeon, S.; Gale, C.

    2014-08-01

    We compute the transport coefficients that appear in the fluid-dynamical equations for the bulk viscous pressure and shear-stress tensor using the 14-moment approximation in the limit of small, but finite, masses. In this limit, we are able to express all these coefficients in terms of known thermodynamic quantities, such as the thermodynamic pressure, energy density, and the velocity of sound. We explicitly demonstrate that the ratio of bulk viscosity to bulk relaxation time behaves very differently, as a function of temperature, than the ratio of shear viscosity to shear relaxation time. We further explicitly compute, for the first time, the transport coefficients that couple the bulk viscous pressure to the shear-stress tensor and vice versa. The coefficient that couples bulk viscous pressure to shear-stress tensor is found to be orders of magnitude larger than the bulk viscosity itself, suggesting that bulk viscous pressure production owes more to this coupling than to the expansion rate of the system.

  6. Hydrogels: DNA bulks up

    NASA Astrophysics Data System (ADS)

    Labean, Thom

    2006-10-01

    Since the 1940s DNA has been known as the genetic material connected to heredity, and from the early 1980s it has also been considered as a potential structural material for nanoscale construction. Now, a hydrogel made entirely of DNA brings this molecule into the realm of bulk materials.

  7. Models for viscosity and shear localization in bubble-rich magmas

    NASA Astrophysics Data System (ADS)

    Vona, Alessandro; Ryan, Amy G.; Russell, James K.; Romano, Claudia

    2016-09-01

    Bubble content influences magma rheology and, thus, styles of volcanic eruption. Increasing magma vesicularity affects the bulk viscosity of the bubble-melt suspension and has the potential to promote non-Newtonian behavior in the form of shear localization or brittle failure. Here, we present a series of high temperature uniaxial deformation experiments designed to investigate the effect of bubbles on the magma bulk viscosity. The starting materials are cores of natural rhyolitic obsidian synthesized to have variable vesicularity (ϕ = 0- 66%). The foamed cores were deformed isothermally (T = 750 °C) at atmospheric conditions using a high-temperature uniaxial press under constant displacement rates (strain rates between 0.5- 1 ×10-4 s-1) and to total strains of 10-40%. The viscosity of the bubble-free melt (η0) was measured by micropenetration and parallel plate methods to establish a baseline for experiments on the vesicle rich cores. At the experimental conditions, rising vesicle content produces a marked decrease in bulk viscosity that is best described by a two-parameter empirical equation: log10 ⁡ηBulk =log10 ⁡η0 - 1.47[ ϕ / (1 - ϕ) ] 0.48. Our parameterization of the bubble-melt rheology is combined with Maxwell relaxation theory to map the potential onset of non-Newtonian behavior (shear localization) in magmas as a function of melt viscosity, vesicularity, and strain rate. For low degrees of strain (i.e. as in our study), the rheological properties of vesicular magmas under different flow types (pure vs. simple shear) are indistinguishable. For high strain or strain rates where simple and pure shear viscosity values may diverge, our model represents a maximum boundary condition. Vesicular magmas can behave as non-Newtonian fluids at lower strain rates than unvesiculated melts, thereby, promoting shear localization and (explosive or non-explosive) magma fragmentation. The extent of shear localization in magma influences outgassing efficiency

  8. Models for viscosity and shear localization in bubble-rich magmas

    NASA Astrophysics Data System (ADS)

    Vona, Alessandro; Ryan, Amy G.; Russell, James K.; Romano, Claudia

    2016-09-01

    Bubble content influences magma rheology and, thus, styles of volcanic eruption. Increasing magma vesicularity affects the bulk viscosity of the bubble-melt suspension and has the potential to promote non-Newtonian behavior in the form of shear localization or brittle failure. Here, we present a series of high temperature uniaxial deformation experiments designed to investigate the effect of bubbles on the magma bulk viscosity. The starting materials are cores of natural rhyolitic obsidian synthesized to have variable vesicularity (ϕ = 0- 66%). The foamed cores were deformed isothermally (T = 750 °C) at atmospheric conditions using a high-temperature uniaxial press under constant displacement rates (strain rates between 0.5- 1 ×10-4 s-1) and to total strains of 10-40%. The viscosity of the bubble-free melt (η0) was measured by micropenetration and parallel plate methods to establish a baseline for experiments on the vesicle rich cores. At the experimental conditions, rising vesicle content produces a marked decrease in bulk viscosity that is best described by a two-parameter empirical equation: log10 ⁡ηBulk =log10 ⁡η0 - 1.47[ ϕ / (1 - ϕ) ] 0.48. Our parameterization of the bubble-melt rheology is combined with Maxwell relaxation theory to map the potential onset of non-Newtonian behavior (shear localization) in magmas as a function of melt viscosity, vesicularity, and strain rate. For low degrees of strain (i.e. as in our study), the rheological properties of vesicular magmas under different flow types (pure vs. simple shear) are indistinguishable. For high strain or strain rates where simple and pure shear viscosity values may diverge, our model represents a maximum boundary condition. Vesicular magmas can behave as non-Newtonian fluids at lower strain rates than unvesiculated melts, thereby, promoting shear localization and (explosive or non-explosive) magma fragmentation. The extent of shear localization in magma influences outgassing efficiency

  9. Viscosity Measurement Using Drop Coalescence in Microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.; Ethridge, Edwin C.; Maxwell, Daniel; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    We present in here validation studies of a new method for application in microgravity environment which measures the viscosity of highly viscous undercooled liquids using drop coalescence. The method has the advantage of avoiding heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Homogeneous nucleation can also be avoided due to the rapidity of the measurement using this method. The technique relies on measurements from experiments conducted in near zero gravity environment as well as highly accurate analytical formulation for the coalescence process. The viscosity of the liquid is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity for two coalescing drops. Results are presented from two sets of validation experiments for the method which were conducted on board aircraft flying parabolic trajectories. In these tests the viscosity of a highly viscous liquid, namely glycerin, was determined at different temperatures using the drop coalescence method described in here. The experiments measured the free surface velocity of two glycerin drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The liquid viscosity was determined by adjusting the computed free surface velocity values to the measured experimental data. The results of these experiments were found to agree reasonably well with the known viscosity for the test liquid used.

  10. Entropy viscosity method applied to Euler equations

    SciTech Connect

    Delchini, M. O.; Ragusa, J. C.; Berry, R. A.

    2013-07-01

    The entropy viscosity method [4] has been successfully applied to hyperbolic systems of equations such as Burgers equation and Euler equations. The method consists in adding dissipative terms to the governing equations, where a viscosity coefficient modulates the amount of dissipation. The entropy viscosity method has been applied to the 1-D Euler equations with variable area using a continuous finite element discretization in the MOOSE framework and our results show that it has the ability to efficiently smooth out oscillations and accurately resolve shocks. Two equations of state are considered: Ideal Gas and Stiffened Gas Equations Of State. Results are provided for a second-order time implicit schemes (BDF2). Some typical Riemann problems are run with the entropy viscosity method to demonstrate some of its features. Then, a 1-D convergent-divergent nozzle is considered with open boundary conditions. The correct steady-state is reached for the liquid and gas phases with a time implicit scheme. The entropy viscosity method correctly behaves in every problem run. For each test problem, results are shown for both equations of state considered here. (authors)

  11. Viscosity of confined inhomogeneous nonequilibrium fluids

    NASA Astrophysics Data System (ADS)

    Zhang, Junfang; Todd, B. D.; Travis, Karl P.

    2004-12-01

    We use the nonlocal linear hydrodynamic constitutive model, proposed by Evans and Morriss [Statistical Mechanics of Nonequilibrium Liquids (Academic, London, 1990)], for computing an effective spatially dependent shear viscosity of inhomogeneous nonequilibrium fluids. The model is applied to a simple atomic fluid undergoing planar Poiseuille flow in a confined channel of several atomic diameters width. We compare the spatially dependent viscosity with a local generalization of Newton's law of viscosity and the Navier-Stokes viscosity, both of which are known to suffer extreme inaccuracies for highly inhomogeneous systems. The nonlocal constitutive model calculates effective position dependent viscosities that are free from the notorious singularities experienced by applying the commonly used local constitutive model. It is simple, general, and has widespread applicability in nanofluidics where experimental measurement of position dependent transport coefficients is currently inaccessible. In principle the method can be used to predict approximate flow profiles of any arbitrary inhomogeneous system. We demonstrate this by predicting the flow profile for a simple fluid undergoing planar Couette flow in a confined channel of several atomic diameters width.

  12. Predicting slag viscosity from coal ash composition

    SciTech Connect

    Laumb, J.; Benson, S.A.; Katrinak, K.A.; Schwalbe, R.; McCollor, D.P.

    1999-07-01

    Management of slag flow from cyclone-fired utility boilers requires accurate prediction of viscosity. Cyclones tend to build up slag when the cyclone combustion temperature is less than the temperature required to melt and tap the ash from the coal being fired. Cyclone-fired boilers designed for lignite are equipped with predry systems, which remove 6-9% of the moisture from the coal. Cyclones tend to slag when the as-received heating value of the fuel is less than 6350 Btu/lb and T250 (temperature where viscosity equals 250 poise) is greater than 2350 F. The T250 value, as well as the rest of the viscosity-temperature relationship, can be predicted using models based on coal ash composition. The focus of this work is to evaluate several models in terms of their agreement with measured viscosities. Viscosity measurements were made for ten samples, including nine lignite coals and one lignite-derived slag. Model performance is related to the SiO{sub 2}, CaO, and Fe{sub 2}O{sub 3} contents of the slag. The Sage and McIlroy and Kalmanovitch models worked best for high SiO{sub 2} and low Fe{sub 2}O{sub 3} fuels. The Senior model worked best when Fe{sub 2}O{sub 3} content was moderate to high.

  13. Viscosity of confined inhomogeneous nonequilibrium fluids.

    PubMed

    Zhang, Junfang; Todd, B D; Travis, Karl P

    2004-12-01

    We use the nonlocal linear hydrodynamic constitutive model, proposed by Evans and Morriss [Statistical Mechanics of Nonequilibrium Liquids (Academic, London, 1990)], for computing an effective spatially dependent shear viscosity of inhomogeneous nonequilibrium fluids. The model is applied to a simple atomic fluid undergoing planar Poiseuille flow in a confined channel of several atomic diameters width. We compare the spatially dependent viscosity with a local generalization of Newton's law of viscosity and the Navier-Stokes viscosity, both of which are known to suffer extreme inaccuracies for highly inhomogeneous systems. The nonlocal constitutive model calculates effective position dependent viscosities that are free from the notorious singularities experienced by applying the commonly used local constitutive model. It is simple, general, and has widespread applicability in nanofluidics where experimental measurement of position dependent transport coefficients is currently inaccessible. In principle the method can be used to predict approximate flow profiles of any arbitrary inhomogeneous system. We demonstrate this by predicting the flow profile for a simple fluid undergoing planar Couette flow in a confined channel of several atomic diameters width. PMID:15549963

  14. Effect of viscosity on learned satiation.

    PubMed

    Mars, M; Hogenkamp, P S; Gosses, A M; Stafleu, A; De Graaf, C

    2009-08-01

    A higher viscosity of a food leads to a longer orosensory stimulation. This may facilitate the learned association between sensory signals and metabolic consequences. In the current study we investigated the effect of viscosity on learned satiation. In two intervention groups a low viscosity (LV) yogurt (n=24) and a high viscosity (HV) yogurt (n=22) was offered ad libitum for breakfast. In a learning period of 4 weeks, subjects consumed ad libitum a novel flavoured high energy density (HED) yogurt (150 kcal/100 g) or low energy density (LED) yogurt (50 kcal/100 g), with 10 exposures to each yogurt on alternate days. Over the repeated exposures, an interaction effect of exposure timeenergyviscosity on intake was seen (F(1,771)=4.12; p=0.04). In the HV intervention group a borderline significant interaction between exposure and energy density was observed (F(1,369)=3.61; p=0.06); after 10 exposures, the LED yogurt resulted in a 46+/-16 g higher intake compared with the HED yogurt. In the LV group, no significant interaction between exposure and energy density was seen (F(1,401)=1.04; p=0.31); after 10 exposures intake difference between the LED and HED yogurts was only 1.5+/-15 g. These results suggest that a higher viscosity facilitates learned satiation. PMID:19394350

  15. Probing Rotational Viscosity in Synaptic Vesicles

    PubMed Central

    Zeigler, Maxwell B.; Allen, Peter B.; Chiu, Daniel T.

    2011-01-01

    The synaptic vesicle (SV) is a central organelle in neurotransmission, and previous studies have suggested that SV protein 2 (SV2) may be responsible for forming a gel-like matrix within the vesicle. Here we measured the steady-state rotational anisotropy of the fluorescent dye, Oregon Green, within individual SVs. By also measuring the fluorescence lifetime of Oregon Green in SVs, we determined the mean rotational viscosity to be 16.49 ± 0.12 cP for wild-type (WT) empty mice vesicles (i.e., with no neurotransmitters), 11.21 ± 0.12 cP for empty vesicles from SV2 knock-out mice, and 11.40 ± 0.65 cP for WT mice vesicles loaded with the neurotransmitter glutamate (Glu). This measurement shows that SV2 is an important determinant of viscosity within the vesicle lumen, and that the viscosity decreases when the vesicles are filled with Glu. The viscosities of both empty SV2 knock-out vesicles and Glu-loaded WT vesicles were significantly different from that of empty WT SVs (p < 0.05). This measurement represents the smallest enclosed volume in which rotational viscosity has been measured thus far. PMID:21641331

  16. Modified Alternan: A Novel Microbial Gum with Potential as a Low-Viscosity Bulking Agent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alternan is a microbial gum produced by rare strains of the GRAS lactic acid bacterium, Leuconostoc mesenteroides. The unique alternating alpha-(1,6) and alpha-(1,3) linkage pattern of this glucan imparts high solubility and resistance to most digestive enzymes. Previously, we invented a bioconver...

  17. Viscosity jump in Earth's mid-mantle.

    PubMed

    Rudolph, Maxwell L; Lekić, Vedran; Lithgow-Bertelloni, Carolina

    2015-12-11

    The viscosity structure of Earth's deep mantle affects the thermal evolution of Earth, the ascent of mantle plumes, settling of subducted oceanic lithosphere, and the mixing of compositional heterogeneities in the mantle. Based on a reanalysis of the long-wavelength nonhydrostatic geoid, we infer viscous layering of the mantle using a method that allows us to avoid a priori assumptions about its variation with depth. We detect an increase in viscosity at 800- to 1200-kilometers depth, far greater than the depth of the mineral phase transformations that define the mantle transition zone. The viscosity increase is coincident in depth with regions where seismic tomography has imaged slab stagnation, plume deflection, and changes in large-scale structure and offers a simple explanation of these phenomena. PMID:26659053

  18. Diffusion, Viscosity and Crystal Growth in Microgravity

    NASA Technical Reports Server (NTRS)

    Myerson, Allan S.

    1996-01-01

    The diffusivity of TriGlycine Sulfate (TGS), Potassium Dihydrogen Phosphate (KDP), Ammonium Dihydrogen Phosphate (ADF) and other compounds of interest to microgravity crystal growth, in supersaturated solutions as a function of solution concentration, 'age' and 'history was studied experimentally. The factors that affect the growth of crystals from water solutions in microgravity have been examined. Three non-linear optical materials have been studied, potassium dihydrogen phosphate (KDP), ammonium dihydrogen phosphate (ADP) and triglycine sulfate (TGC). The diffusion coefficient and viscosity of supersaturated water solutions were measured. Also theoretical model of diffusivity and viscosity in a metastable state, model of crystal growth from solution including non-linear time dependent diffusivity and viscosity effect and computer simulation of the crystal growth process which allows simulation of the microgravity crystal growth were developed.

  19. Polyfunctional dispersants for controlling viscosity of phyllosilicates

    DOEpatents

    Chaiko, David J.

    2006-07-25

    This invention provides phyllosilicates and polyfunctional dispersants which can be manipulated to selectively control the viscosity of phyllosilicate slurries. The polyfunctional dispersants used in the present invention, which include at least three functional groups, increase the dispersion and exfoliation of phyllosilicates in polymers and, when used in conjunction with phyllosilicate slurries, significantly reduce the viscosity of slurries having high concentrations of phyllosilicates. The functional groups of the polyfunctional dispersants are capable of associating with multivalent metal cations and low molecular weight organic polymers, which can be manipulated to substantially increase or decrease the viscosity of the slurry in a concentration dependent manner. The polyfunctional dispersants of the present invention can also impart desirable properties on the phyllosilicate dispersions including corrosion inhibition and enhanced exfoliation of the phyllosilicate platelets.

  20. Increased blood viscosity in diabetic proliferative retinopathy.

    PubMed

    Lowe, G D; Ghafour, I M; Belch, J J; Forbes, C D; Foulds, W S; MacCuish, A C

    1986-02-01

    Blood rheology and haemostasis were assessed in 18 diabetics with proliferative retinopathy and in 18 diabetics without proliferative retinopathy, matched for age, sex, smoking habit and type, duration and treatment of diabetes. Proliferative retinopathy was associated with significantly higher levels of blood viscosity at high and low shear rates, which were related to higher levels of plasma viscosity and fibrinogen. Blood urea, glucose, glycosylated haemoglobin and white cell count were also significantly higher, whereas haematocrit, red cell deformability and several other haematological and biochemical variables did not differ significantly in the 2 groups. In view of these findings, and of our recent demonstration that increased blood viscosity also exists in those patients with retinal vein occlusion who develop a similar proliferative retinopathy, we suggest that hyperviscosity may contribute to retinal ischaemia and hence proliferative retinopathy. PMID:3698481

  1. Viscosity Meaurement Technique for Metal Fuels

    SciTech Connect

    Ban, Heng; Kennedy, Rory

    2015-02-09

    Metallic fuels have exceptional transient behavior, excellent thermal conductivity, and a more straightforward reprocessing path, which does not separate out pure plutonium from the process stream. Fabrication of fuel containing minor actinides and rare earth (RE) elements for irradiation tests, for instance, U-20Pu-3Am-2Np-1.0RE-15Zr samples at the Idaho National Laboratory, is generally done by melt casting in an inert atmosphere. For the design of a casting system and further scale up development, computational modeling of the casting process is needed to provide information on melt flow and solidification for process optimization. Therefore, there is a need for melt viscosity data, the most important melt property that controls the melt flow. The goal of the project was to develop a measurement technique that uses fully sealed melt sample with no Americium vapor loss to determine the viscosity of metallic melts and at temperatures relevant to the casting process. The specific objectives of the project were to: develop mathematical models to establish the principle of the measurement method, design and build a viscosity measurement prototype system based on the established principle, and calibrate the system and quantify the uncertainty range. The result of the project indicates that the oscillation cup technique is applicable for melt viscosity measurement. Detailed mathematical models of innovative sample ampoule designs were developed to not only determine melt viscosity, but also melt density under certain designs. Measurement uncertainties were analyzed and quantified. The result of this project can be used as the initial step toward the eventual goal of establishing a viscosity measurement system for radioactive melts.

  2. Viscosity properties of sodium borophosphate glasses

    SciTech Connect

    Gaylord, S.; Tincher, B.; Petit, L. Richardson, K.

    2009-05-06

    The viscosity behavior of (1 - x)NaPO{sub 3}-xNa{sub 2}B{sub 4}O{sub 7} glasses (x = 0.05-0.20) have been measured as a function of temperature using beam-bending and parallel-plate viscometry. The viscosity was found to shift to higher temperatures with increasing sodium borate content. The kinetic fragility parameter, m, estimated from the viscosity curve, decreases from 52 to 33 when x increases from 0.05 to 0.20 indicating that the glass network transforms from fragile to strong with the addition of Na{sub 2}B{sub 4}O{sub 7}. The decrease in fragility with increasing x is due to the progressive depolymerization of the phosphate network by the preferred four-coordinated boron atoms present in the low alkali borate glasses. As confirmed by Raman spectroscopy increasing alkali borate leads to enhanced B-O-P linkages realized with the accompanying transition from solely four-coordinated boron (in BO{sub 4} units) to mixed BO{sub 4}/BO{sub 3} structures. The glass viscosity characteristics of the investigated glasses were compared to those of P-SF67 and N-FK5 commercial glasses from SCHOTT. We showed that the dependence of the viscosity of P-SF67 was similar to the investigated glasses due to similar phosphate network organization confirmed by Raman spectroscopy, whereas N-FK5 exhibited a very different viscosity curve and fragility parameter due to its highly coordinated silicate network.

  3. Slim accretion discs with different viscosity prescriptions

    NASA Astrophysics Data System (ADS)

    Szuszkiewicz, Ewa

    1990-05-01

    The variability of X-ray sources powered by accretion may be connected to thermal instabilities in the innermost parts of slim disks. The time-scales of variability predicted by the theory with the standard alpha-viscosity prescription agree with those observed in a wide range of sources. The amplitudes (3-4 orders of magnitude in luiminosity) are correctly predicted for X-ray transient sources, but in general are too big for quasars, Seyferts, galactic blackhole candidates and LMXBs. It is shown that a slight modification of the viscosity prescription can offer a much better agreement with observations.

  4. Measuring Viscosities of Gases at Atmospheric Pressure

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

    1987-01-01

    Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

  5. Rare Gas Viscosities: A Learning Tool

    NASA Astrophysics Data System (ADS)

    Halpern, Arthur M.

    2002-02-01

    The viscosities, h, of the rare gases and SF6 are determined in a physical chemistry laboratory experiment using the evacuation method, which is based on Poiseuille's equation. Students become aware that h does not vary monotonically with row number (or atomic mass) and confirm this behavior on the basis of the kinetic theory expression for h. They find that the collision diameters of the gases, s, which are obtained from h values, increase monotonically with molar mass, as expected. Students can show that values of s obtained from gas viscosities agree reasonably well with ab initio calculations of atomic (molecular) diameters using Gaussian 98W.

  6. Shear viscosity coefficient of liquid lanthanides

    SciTech Connect

    Patel, H. P. Thakor, P. B. Prajapati, A. V.; Sonvane, Y. A.

    2015-05-15

    Present paper deals with the computation of shear viscosity coefficient (η) of liquid lanthanides. The effective pair potential v(r) is calculated through our newly constructed model potential. The Pair distribution function g(r) is calculated from PYHS reference system. To see the influence of local field correction function, Hartree (H), Tailor (T) and Sarkar et al (S) local field correction function are used. Present results are compared with available experimental as well as theoretical data. Lastly, we found that our newly constructed model potential successfully explains the shear viscosity coefficient (η) of liquid lanthanides.

  7. Apparatus and method for measuring viscosity

    DOEpatents

    Murphy, R.J. Jr.

    1986-02-25

    The present invention is directed to an apparatus and method for measuring the viscosity of a fluid. This apparatus and method is particularly useful for the measurement of the viscosity of a liquid in a harsh environment characterized by high temperature and the presence of corrosive or deleterious gases and vapors which adversely affect conventional ball or roller bearings. The apparatus and method of the present invention employ one or more flexural or torsional bearings to suspend a bob capable of limited angular motion within a rotatable sleeve suspended from a stationary frame. 7 figs.

  8. Apparatus and method for measuring viscosity

    DOEpatents

    Murphy, Jr., Robert J.

    1986-01-01

    The present invention is directed to an apparatus and method for measuring the viscosity of a fluid. This apparatus and method is particularly useful for the measurement of the viscosity of a liquid in a harsh environment characterized by high temperature and the presence of corrosive or deleterious gases and vapors which adversely affect conventional ball or roller bearings. The apparatus and method of the present invention employ one or more flexural or torsional bearings to suspend a bob capable of limited angular motion within a rotatable sleeve suspended from a stationary frame.

  9. Shock capturing by the spectral viscosity method

    NASA Technical Reports Server (NTRS)

    Tadmor, Eitan

    1989-01-01

    A main disadvantage of using spectral methods for nonlinear conservation laws lies in the formation of Gibbs phenomenon, once spontaneous shock discontinuities appear in the solution. The global nature of spectral methods than pollutes the unstable Gibbs oscillations overall the computational domain, and the lack of entropy dissipation prevents convergences in these cases. The Spectral Viscosity method, which is based on high frequency dependent vanishing viscosity regularization of the classical spectral methods is discussed. It is shown that this method enforces the convergence of nonlinear spectral approximations without sacrificing their overall spectral accuracy.

  10. Gravimetric capillary method for kinematic viscosity measurements

    NASA Technical Reports Server (NTRS)

    Rosenberger, Franz; Iwan, J.; Alexander, D.; Jin, Wei-Qing

    1992-01-01

    A novel version of the capillary method for viscosity measurements of liquids is presented. Viscosity data can be deduced in a straightforward way from mass transfer data obtained by differential weighing during the gravity-induced flow of the liquid between two cylindrical chambers. Tests of this technique with water, carbon tetrachloride, and ethanol suggest that this arrangement provides an accuracy of about +/- 1 percent. The technique facilitates operation under sealed, isothermal conditions and, thus can readily be applied to reactive and/or high vapor pressure liquids.

  11. Wave Speeds, Riemann Solvers and Artificial Viscosity

    SciTech Connect

    Rider, W.J.

    1999-07-18

    A common perspective on the numerical solution of the equation Euler equations for shock physics is examined. The common viewpoint is based upon the selection of nonlinear wavespeeds upon which the dissipation (implicit or explicit) is founded. This perspective shows commonality between Riemann solver based method (i.e. Godunov-type) and artificial viscosity (i.e. von Neumann-Richtmyer). As an example we derive an improved nonlinear viscous stabilization of a Richtmyer-Lax-Wendroff method. Additionally, we will define a form of classical artificial viscosity based upon the HLL Riemann solver.

  12. Bulk Email Forensics

    NASA Astrophysics Data System (ADS)

    Cohen, Fred

    Legal matters related to unsolicited commercial email often involve several hundred thousand messages. Manual examination and interpretation methods are unable to deal with such large volumes of evidence. Furthermore, as the actors gain experience, it is increasingly difficult to show evidence of spoliation and detect intentional evidence construction. This paper presents improved automated techniques for bulk email analysis and presentation to aid in evidence interpretation.

  13. Extended Driving Impairs Nocturnal Driving Performances

    PubMed Central

    Sagaspe, Patricia; Taillard, Jacques; Åkerstedt, Torbjorn; Bayon, Virginie; Espié, Stéphane; Chaumet, Guillaume; Bioulac, Bernard; Philip, Pierre

    2008-01-01

    Though fatigue and sleepiness at the wheel are well-known risk factors for traffic accidents, many drivers combine extended driving and sleep deprivation. Fatigue-related accidents occur mainly at night but there is no experimental data available to determine if the duration of prior driving affects driving performance at night. Participants drove in 3 nocturnal driving sessions (3–5am, 1–5am and 9pm–5am) on open highway. Fourteen young healthy men (mean age [±SD] = 23.4 [±1.7] years) participated Inappropriate line crossings (ILC) in the last hour of driving of each session, sleep variables, self-perceived fatigue and sleepiness were measured. Compared to the short (3–5am) driving session, the incidence rate ratio of inappropriate line crossings increased by 2.6 (95% CI, 1.1 to 6.0; P<.05) for the intermediate (1–5am) driving session and by 4.0 (CI, 1.7 to 9.4; P<.001) for the long (9pm–5am) driving session. Compared to the reference session (9–10pm), the incidence rate ratio of inappropriate line crossings were 6.0 (95% CI, 2.3 to 15.5; P<.001), 15.4 (CI, 4.6 to 51.5; P<.001) and 24.3 (CI, 7.4 to 79.5; P<.001), respectively, for the three different durations of driving. Self-rated fatigue and sleepiness scores were both positively correlated to driving impairment in the intermediate and long duration sessions (P<.05) and increased significantly during the nocturnal driving sessions compared to the reference session (P<.01). At night, extended driving impairs driving performances and therefore should be limited. PMID:18941525

  14. Electrical drive for automobile

    SciTech Connect

    Fobbs, H.

    1980-09-16

    Electrical apparatus for driving an automobile is described that is comprised of a dc motor operationally connected to the rear axle through a drive shaft with the motor energized from storage batteries and recharged from alternators coupled to the drive shaft adjacent a clutch at the rear end of the automobile through an auxiliary drive shaft.

  15. Coaxial Redundant Drives

    NASA Technical Reports Server (NTRS)

    Brissette, R.

    1983-01-01

    Harmonic drives allow redundancy and high out put torque in small package. If main drive fails, standby drive takes over and produces torque along same axis as main drive. Uses include power units in robot for internal pipeline inspection, manipulators in deep submersible probes or other applications in which redundancy protects against costly failures.

  16. Spiders Tune Glue Viscosity to Maximize Adhesion.

    PubMed

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives. PMID:26513350

  17. Commensurability Effects in Viscosity of Nanoconfined Water.

    PubMed

    Neek-Amal, Mehdi; Peeters, Francois M; Grigorieva, Irina V; Geim, Andre K

    2016-03-22

    The rate of water flow through hydrophobic nanocapillaries is greatly enhanced as compared to that expected from macroscopic hydrodynamics. This phenomenon is usually described in terms of a relatively large slip length, which is in turn defined by such microscopic properties as the friction between water and capillary surfaces and the viscosity of water. We show that the viscosity of water and, therefore, its flow rate are profoundly affected by the layered structure of confined water if the capillary size becomes less than 2 nm. To this end, we study the structure and dynamics of water confined between two parallel graphene layers using equilibrium molecular dynamics simulations. We find that the shear viscosity is not only greatly enhanced for subnanometer capillaries, but also exhibits large oscillations that originate from commensurability between the capillary size and the size of water molecules. Such oscillating behavior of viscosity and, consequently, the slip length should be taken into account in designing and studying graphene-based and similar membranes for desalination and filtration. PMID:26882095

  18. Pressure-viscosity coefficient of biobased lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Film thickness is an important tribological property that is dependent on the combined effect of lubricant properties, material property of friction surfaces, and the operating conditions of the tribological process. Pressure-viscosity coefficient (PVC) is one of the lubricant properties that influe...

  19. Heat flux viscosity in collisional magnetized plasmas

    SciTech Connect

    Liu, C.; Fox, W.; Bhattacharjee, A.

    2015-05-15

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  20. Electron perpendicular viscosity in Braginskii's equations

    SciTech Connect

    Wong, S. K.; Chan, V. S.

    2013-07-15

    The viscosity coefficient of the electron perpendicular stress tensor in Braginskii's theory is corrected by the addition of a term of the same order of magnitude, through the inclusion of a term beyond pitch angle scattering in the mass-ratio expansion of the electron-ion collision operator.

  1. Viscosity Measurement using Drop Coalescence in Microgravity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.; Ethridge, Edwin; Maxwell, Daniel

    1999-01-01

    We present in here details of a new method, using drop coalescence, for application in microgravity environment for determining the viscosity of highly viscous undercooled liquids. The method has the advantage of eliminating heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Also, due to the rapidity of the measurement, homogeneous nucleation would be avoided. The technique relies on both a highly accurate solution to the Navier-Stokes equations as well as on data gathered from experiments conducted in near zero gravity environment. The liquid viscosity is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity of two coalescing drops. Results are presented from two validation experiments of the method which were conducted recently on board the NASA KC-135 aircraft. In these tests the viscosity of a highly viscous liquid, such as glycerine at different temperatures, was determined to reasonable accuracy using the liquid coalescence method. The experiments measured the free surface velocity of two glycerine drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The free surface velocity was then compared with the computed values obtained from different viscosity values. The results of these experiments were found to agree reasonably well with the calculated values.

  2. Viscosity of endodontic irrigants: Influence of temperature

    PubMed Central

    Poggio, Claudio; Ceci, Matteo; Beltrami, Riccardo; Colombo, Marco; Dagna, Alberto

    2015-01-01

    Background: The aim of this study was to assess the influence of temperature on the viscosity of different endodontic irrigants. Materials and Methods: The measurements of viscosity of 3% hydrogen peroxide, 0.9% sodium chloride, aqueous solution of 0.2% chlorhexidine (CHX) and 0.2% cetrimide, 5% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA) at different temperatures (22°C, 30°C, 40°C, 50°C and 60°C) were obtained using Mohr balance and Ostwald viscometer. The Shapiro-Wilk test and Mann-Whitney U-tests were used for the statistical analysis. (α = 0.05). Results: No significant differences were recorded at each temperature among 3% hydrogen peroxide, 0.9% sodium chloride and aqueous solution of 0.2% CHX and 0.2% cetrimide. 5% NaOCl and 17% EDTA showed the higher values. Viscosity statistically decreased with increasing temperature. Conclusion: Within the limitations of this study, 5% NaOCl and 17% EDTA are significantly viscous at room temperature and their viscosity reduces with elevating temperature. PMID:26604955

  3. Pressure viscosity coefficient of vegetable oils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The elastohydrodynamic (EHD) pressure viscosity coefficient (PVC) of ten vegetable oils from commodity and new crops, and two petroleum-based oils, polyalphaolefin (PAO) and hexadecane, were investigated. PVC was measured using three different methods: the So and Klaus (S-K) procedure from oil visco...

  4. Sensor for Viscosity and Shear Strength Measurement

    SciTech Connect

    Dillon, J.; Moore, J.E. Jr.; Ebadian, M.A.; Jones, W.K.

    1998-10-20

    Measurement of the physical properties (viscosity and density) of waste slurries is critical in evaluating transport parameters to ensure turbulent flow through transport pipes. The environment for measurement and sensor exposure is extremely harsh; therefore, reliability and ruggedness are critical in the sensor design. The work for this project will be performed in three phases. The first phase, carried out in FY96, involved (1) an evaluation of acoustic and other methods for viscosity measurement; (2) measurement of the parameters of slurries over the range of percent solids found in tanks and transport systems; (3) a comparison of physical properties (e.g., viscosity and density) to percent solids found composition; and (4) the design of a prototype sensor. The second phase (FY97) will involve the fabrication of a prototype hybrid sensor to measure the viscosity and mechanical properties of slurries in remote, high-radiation environments. Two different viscometer designs are being investigated in this study: a magnetostrictive pulse wave guide viscometer; an oscillating cylinder viscometer. In FY97, the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU), which has printed circuit, thick film, thin film, and co-fired ceramic fabrication capability, will fabricate five probes for demonstration after technology selection and evaluation.

  5. Heat flux viscosity in collisional magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Liu, C.; Fox, W.; Bhattacharjee, A.

    2015-05-01

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a "heat flux viscosity," is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  6. Belt conveyors for bulk materials. 6th ed.

    SciTech Connect

    2007-07-01

    The 16 chapters are entitled: Belt conveyor general applications economics; Design considerations; Characteristics and conveyability of bulk materials; Capacities, belt widths and speeds; Belt conveyor idlers; Belt tension and power engineering; Belt selection; Pulleys and shafts; Curves; Steep angle conveying; Belt cleaners and accessories; Transfer points; Conveyor motor drives and controls; Operation, maintenance and safety; Belt takeups; and Emerging technologies. 6 apps.

  7. Reference Correlation for the Viscosity of Ethane

    NASA Astrophysics Data System (ADS)

    Vogel, Eckhard; Span, Roland; Herrmann, Sebastian

    2015-12-01

    A new representation of the viscosity for the fluid phase of ethane includes a zero-density correlation and a contribution for the critical enhancement, initially both developed separately, but based on experimental data. The higher-density contributions are correlated as a function of the reduced density δ = ρ/ρc and of the reciprocal reduced temperature τ = Tc/T (ρc—critical density and Tc—critical temperature). The final formulation contains 14 coefficients obtained using a state-of-the-art linear optimization algorithm. The evaluation and choice of the selected primary data sets is reviewed, in particular with respect to the assessment used in earlier viscosity correlations. The new viscosity surface correlation makes use of the reference equation of state for the thermodynamic properties of ethane by Bücker and Wagner [J. Phys. Chem. Ref. Data 35, 205 (2006)] and is valid in the fluid region from the melting line to temperatures of 675 K and pressures of 100 MPa. The viscosity in the limit of zero density is described with an expanded uncertainty of 0.5% (coverage factor k = 2) for temperatures 290 < T/K < 625, increasing to 1.0% at temperatures down to 212 K. The uncertainty of the correlated values is 1.5% in the range 290 < T/K < 430 at pressures up to 30 MPa on the basis of recent measurements judged to be very reliable as well as 4.0% and 6.0% in further regions. The uncertainty in the near-critical region (1.001 < 1/τ < 1.010 and 0.8 < δ < 1.2) increases with decreasing temperature up to 3.0% considering the available reliable data. Tables of the viscosity calculated from the correlation are listed in an appendix for the single-phase region, for the vapor-liquid phase boundary, and for the near-critical region.

  8. Solar array drive system

    NASA Technical Reports Server (NTRS)

    Berkopec, F. D.; Sturman, J. C.; Stanhouse, R. W.

    1976-01-01

    A solar array drive system consisting of a solar array drive mechanism and the corresponding solar array drive electronics is being developed. The principal feature of the solar array drive mechanism is its bidirectional capability which enables its use in mechanical redundancy. The solar array drive system is of a widely applicable design. This configuration will be tested to determine its acceptability for generic mission sets. Foremost of the testing to be performed is the testing for extended duration.

  9. Half-Order Stable Boundary-Layer Parametrization Without the Eddy Viscosity Approach for Use in Numerical Weather Prediction

    NASA Astrophysics Data System (ADS)

    Foreman, Richard J.; Emeis, Stefan; Canadillas, Beatriz

    2015-02-01

    A turbulence parametrization for wind speed in the stable boundary layer consisting of a single empirical parameter is proposed without the use of the eddy viscosity concept or turbulent kinetic energy equation. Instead, a drag-coefficient-type formulation as a function of the bulk Richardson number has been found to be able to reproduce observed stable boundary-layer wind speeds as effectively as a model based on the eddy viscosity approach. The advantage of this simpler approach is that the model can, in theory, be modified more easily for certain applications, such as the effects of large-scale wind parks on mesoscale meteorology.

  10. Low viscosity reversed hexagonal mesophases induced by hydrophilic additives.

    PubMed

    Amar-Yuli, Idit; Wachtel, Ellen; Shalev, Deborah E; Aserin, Abraham; Garti, Nissim

    2008-04-01

    This study reports on the formation of a low viscosity H(II) mesophase at room temperature upon addition of Transcutol (diethylene glycol mono ethyl ether) or ethanol to the ternary mixture of GMO (glycerol monooleate)/TAG (tricaprylin)/water. The microstructure and bulk properties were characterized in comparison with those of the low viscosity HII mesophase formed in the ternary GMO/TAG/water mixture at elevated temperatures (35-40 degrees C). We characterized the role of Transcutol or ethanol as inducers of disorder and surfactant mobility. The techniques used were rheology, differential scanning calorimetry (DSC), wide- and small-angle X-ray scattering (WAXS and SAXS, respectively), NMR (self-diffusion and (2)H NMR), and Fourier transform infrared (FTIR) spectroscopies. The incorporation of either Transcutol or ethanol induced the formation of less ordered HII mesophases with smaller domain sizes and lattice parameters at room temperature (up to 30 degrees C), similar to those found for the GMO/TAG/water mixture at more elevated temperatures (35-40 degrees C). On the basis of our measurements, we suggest that Transcutol or ethanol causes dehydration of the GMO headgroups and enhances the mobility of the GMO chains. As a result, these two small molecules, which compete for water with the GMO polar headgroups, may increase the curvature of the cylindrical micelles and also perhaps reduce their length. This results in the formation of fluid H(II) structures at room temperature (up to 30 degrees C). It is possible that these phases are a prelude to the H(II)-L(2) transformation, which takes place above 35 degrees C. PMID:18324809

  11. Bulk-barrier transistor

    NASA Astrophysics Data System (ADS)

    Mader, H.; Mueller, R.; Beinvogl, W.

    1983-10-01

    Experimental and theoretical results are presented on a bulk-barrier transistor (BBT). In this device the charge-carrier transportation is determined by an energy barrier, which is located inside a semiconductor. The barrier is the result of a space-charge region in a three-layered n-p-n or p-n-p structure with a very thin middle layer. The height of the energy barrier, which is adjustable by technological parameters, can be controlled by an external voltage.

  12. Numerical studies of thermal convection with temperature- and pressure-dependent viscosity at extreme viscosity contrasts

    NASA Astrophysics Data System (ADS)

    Khaleque, Tania S.; Fowler, A. C.; Howell, P. D.; Vynnycky, M.

    2015-07-01

    Motivated by convection of planetary mantles, we consider a mathematical model for Rayleigh-Bénard convection in a basally heated layer of a fluid whose viscosity depends strongly on temperature and pressure, defined in an Arrhenius form. The model is solved numerically for extremely large viscosity variations across a unit aspect ratio cell, and steady solutions for temperature, isotherms, and streamlines are obtained. To improve the efficiency of numerical computation, we introduce a modified viscosity law with a low temperature cutoff. We demonstrate that this simplification results in markedly improved numerical convergence without compromising accuracy. Continued numerical experiments suggest that narrow cells are preferred at extreme viscosity contrasts, and this conclusion is supported by a linear stability analysis.

  13. Dynamic Acid/Base Equilibrium in Single Component Switchable Ionic Liquids and Consequences on Viscosity.

    PubMed

    Cantu, David C; Lee, Juntaek; Lee, Mal-Soon; Heldebrant, David J; Koech, Phillip K; Freeman, Charles J; Rousseau, Roger; Glezakou, Vassiliki-Alexandra

    2016-05-01

    The deployment of transformational nonaqueous CO2-capture solvent systems is encumbered by high viscosities even at intermediate uptakes. Using single-molecule CO2 binding organic liquids as a prototypical example, we present key molecular features that control bulk viscosity. Fast CO2-uptake kinetics arise from close proximity of the alcohol and amine sites involved in CO2 binding in a concerted fashion, resulting in a Zwitterion containing both an alkyl-carbonate and a protonated amine. The population of internal hydrogen bonds between the two functional groups determines the solution viscosity. Unlike the ion pair interactions in ionic liquids, these observations are novel and specific to a hydrogen-bonding network that can be controlled by chemically tuning single molecule CO2 capture solvents. We present a molecular design strategy to reduce viscosity by shifting the proton transfer equilibrium toward a neutral acid/amine species, as opposed to the ubiquitously accepted zwitterionic state. The molecular design concepts proposed here are readily extensible to other CO2 capture technologies. PMID:27019342

  14. Bulk viscous matter-dominated Universes: asymptotic properties

    SciTech Connect

    Avelino, Arturo; García-Salcedo, Ricardo; Gonzalez, Tame; Nucamendi, Ulises; Quiros, Israel E-mail: rigarcias@ipn.mx E-mail: ulises@ifm.umich.mx

    2013-08-01

    By means of a combined use of the type Ia supernovae and H(z) data tests, together with the study of the asymptotic properties in the equivalent phase space — through the use of the dynamical systems tools — we demonstrate that the bulk viscous matter-dominated scenario is not a good model to explain the accepted cosmological paradigm, at least, under the parametrization of bulk viscosity considered in this paper. The main objection against such scenarios is the absence of conventional radiation and matter-dominated critical points in the phase space of the model. This entails that radiation and matter dominance are not generic solutions of the cosmological equations, so that these stages can be implemented only by means of unique and very specific initial conditions, i. e., of very unstable particular solutions. Such a behavior is in marked contradiction with the accepted cosmological paradigm which requires of an earlier stage dominated by relativistic species, followed by a period of conventional non-relativistic matter domination, during which the cosmic structure we see was formed. Also, we found that the bulk viscosity is positive just until very late times in the cosmic evolution, around z < 1. For earlier epochs it is negative, been in tension with the local second law of thermodynamics.

  15. Rapid and simultaneous estimation of fault slip and heterogeneous lithospheric viscosity from post-seismic deformation

    NASA Astrophysics Data System (ADS)

    Hines, T. T.; Hetland, E. A.

    2016-01-01

    Post-seismic deformation is commonly attributed to viscoelastic relaxation and/or afterslip, although discerning between the two driving mechanisms can be difficult. A major complication in modeling post-seismic deformation is that forward models can be computationally expensive, making it difficult to adequately search model space to find the optimal fault slip distribution and lithospheric viscosity structure that can explain observable post-seismic deformation. We propose an inverse method which uses coseismic and early post-seismic deformation to rapidly and simultaneously estimate a fault slip history and an arbitrarily discretized viscosity structure of the lithosphere. Our method is based on an approximation which is applicable to the early post-seismic period and expresses surface deformation resulting from viscoelastic relaxation as a linearized function with respect to lithospheric fluidity. We demonstrate this approximation using two-dimensional earthquake models. We validate the approximation and our inverse method using two three-dimensional synthetic tests. The success of our synthetic tests suggests that our method is capable of distinguishing the mechanisms driving early post-seismic deformation and recovering an effective viscosity structure of the lithosphere.

  16. Magnetic effect in viscosity of magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Fonseca, H. A.; Gonzalez, E.; Restrepo, J.; Parra, C. A.; Ortiz, C.

    2016-02-01

    In this work the study of viscosity is presented for a magnetorheological fluid made from iron oxides micrometre, under an external magnetic field. The material was characterized by magnetic loops in a vibrating sample magnetometer and its crystal structure by X-ray diffraction. The results show that saturation magnetization and coercive field have dependence with the powder size. The material has different crystal structure which lattice parameters were determined by Rietveld refinement. The viscosity of the magnetorheological fluid was measured by a viscometer with rotational symmetry with and without external field. This result evidence a dependency on the size, percentage iron oxide and the applied magnetic field, it is due to the hydrodynamic volume of iron oxide interacts with the external magnetic field, increasing the flow resistance.

  17. Low temperature viscosity in elongated ferrofluids

    NASA Astrophysics Data System (ADS)

    Alarcón, T.; Pérez-Madrid, A.; Rubí, J. M.

    1997-12-01

    We have studied the relaxation and transport properties of a ferrofluid in an elongational flow. These properties are influenced by the bistable nature of the potential energy. Bistability comes from the irrotational character of the flow together with the symmetry of the dipoles. Additionally, the presence of a constant magnetic field destroys the symmetry of the potential energy magnetizing the system. We have shown that at a moderate temperature, compared to the height of the energy barrier, the viscosity decreases with respect to the value it would have if the potential were stable. This phenomenon is known as the "negative viscosity" effect. Thermal motion induces jumps of the magnetic moment between the two stable states of the system leading to the aforementioned lowered dissipation effect.

  18. Viscosity of nitrogen near the critical point

    NASA Technical Reports Server (NTRS)

    Basu, R. S.; Sengers, J. V.

    1978-01-01

    The formulation of a quantitative description of the critical enhancement in the shear viscosity of fluids near the gas-liquid critical point is considered. The critical point is a point of marginal thermodynamic stability. In the vicinity of the critical point, large-scale density fluctuations are present in the fluid. The critical enhancement of the transport properties is related to the correlation length. The correlation length is related to the compressibility, thus providing consistency between the equations for the transport properties and the equation of state in the critical region. The critical region parameters for nitrogen are presented in a table. It is found that the critical viscosity enhancement observed by Zozulya and Blagoi (1974) for nitrogen is consistent with current theoretical predictions

  19. Prediction of viscosity of dense fluid mixtures

    NASA Astrophysics Data System (ADS)

    Royal, Damian D.; Vesovic, Velisa; Trusler, J. P. Martin; Wakeham, William. A.

    The Vesovic-Wakeham (VW) method of predicting the viscosity of dense fluid mixtures has been improved by implementing new mixing rules based on the rigid sphere formalism. The proposed mixing rules are based on both Lebowitz's solution of the Percus-Yevick equation and on the Carnahan-Starling equation. The predictions of the modified VW method have been compared with experimental viscosity data for a number of diverse fluid mixtures: natural gas, hexane + hheptane, hexane + octane, cyclopentane + toluene, and a ternary mixture of hydrofluorocarbons (R32 + R125 + R134a). The results indicate that the proposed improvements make possible the extension of the original VW method to liquid mixtures and to mixtures containing polar species, while retaining its original accuracy.

  20. Bulk material handling system

    DOEpatents

    Kleysteuber, William K.; Mayercheck, William D.

    1979-01-01

    This disclosure relates to a bulk material handling system particularly adapted for underground mining and includes a monorail supported overhead and carrying a plurality of conveyors each having input and output end portions with the output end portion of a first of the conveyors positioned above an input end portion of a second of the conveyors, a device for imparting motion to the conveyors to move the material from the input end portions toward the output end portions thereof, a device for supporting at least one of the input and output end portions of the first and second conveyors from the monorail, and the supporting device including a plurality of trolleys rollingly supported by the monorail whereby the conveyors can be readily moved therealong.

  1. Bulk amorphous materials

    SciTech Connect

    Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.

    1998-12-01

    This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.

  2. Bulk muscles, loose cables.

    PubMed

    Liyanage, Chamari R D G; Kodali, Venkata

    2014-01-01

    The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. PMID:25326558

  3. Creating bulk nanocrystalline metal.

    SciTech Connect

    Fredenburg, D. Anthony; Saldana, Christopher J.; Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John; Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  4. Explosive bulk charge

    DOEpatents

    Miller, Jacob Lee

    2015-04-21

    An explosive bulk charge, including: a first contact surface configured to be selectively disposed substantially adjacent to a structure or material; a second end surface configured to selectively receive a detonator; and a curvilinear side surface joining the first contact surface and the second end surface. The first contact surface, the second end surface, and the curvilinear side surface form a bi-truncated hemispherical structure. The first contact surface, the second end surface, and the curvilinear side surface are formed from an explosive material. Optionally, the first contact surface and the second end surface each have a substantially circular shape. Optionally, the first contact surface and the second end surface consist of planar structures that are aligned substantially parallel or slightly tilted with respect to one another. The curvilinear side surface has one of a smooth curved geometry, an elliptical geometry, and a parabolic geometry.

  5. Effective viscosity of magnetic nanofluids through capillaries

    NASA Astrophysics Data System (ADS)

    Patel, Rajesh

    2012-02-01

    The simultaneous effect of magnetic field and temperature on the capillary viscosity of magnetic nanofluid is an important parameter for a new class of applications such as nanoduct flow, nanomotors, micro- and nanofluidic devices, for transformer cooling, magnetic targeted drug delivery, etc. The effective viscosity of a nanofluid is explained based on the rotation of the particles and the effect of torque on it due to an externally applied magnetic field. Two types of fluids are used here, temperature-sensitive and non-temperature-sensitive magnetic nanofluids. In both types of fluids, decrease in effective viscosity with temperature is observed, but in both cases the mechanism for the decrement is quite different. One is due to temperature dependence of the magnetic moment and the other is due to removal of the secondary surfactant. For temperature-sensitive magnetic nanofluids, a Curie temperature of ˜80 ∘C is extracted from this study. For non-temperature-sensitive magnetic nanofluids ˜65% of the secondary surfactant is removed for a change in temperature, ΔT = 40 ∘C. This is analogous with removal of a drug from magnetic particles for targeted drug delivery. Further, a linear dependence of effective viscosity with different capillary size and ξ (angle between magnetic field and flow direction, ξ∈[0,π/2]) is also observed. This linear dependence can also be a good approximation for the study of magnetic drug targeting, as in the human body the capillaries are of different sizes, and the externally applied magnetic field is not always parallel or perpendicular to the drug flow direction.

  6. Effective viscosity of magnetic nanofluids through capillaries.

    PubMed

    Patel, Rajesh

    2012-02-01

    The simultaneous effect of magnetic field and temperature on the capillary viscosity of magnetic nanofluid is an important parameter for a new class of applications such as nanoduct flow, nanomotors, micro- and nanofluidic devices, for transformer cooling, magnetic targeted drug delivery, etc. The effective viscosity of a nanofluid is explained based on the rotation of the particles and the effect of torque on it due to an externally applied magnetic field. Two types of fluids are used here, temperature-sensitive and non-temperature-sensitive magnetic nanofluids. In both types of fluids, decrease in effective viscosity with temperature is observed, but in both cases the mechanism for the decrement is quite different. One is due to temperature dependence of the magnetic moment and the other is due to removal of the secondary surfactant. For temperature-sensitive magnetic nanofluids, a Curie temperature of ~80 °C is extracted from this study. For non-temperature-sensitive magnetic nanofluids ~65% of the secondary surfactant is removed for a change in temperature, ΔT = 40 °C. This is analogous with removal of a drug from magnetic particles for targeted drug delivery. Further, a linear dependence of effective viscosity with different capillary size and ξ (angle between magnetic field and flow direction, ξε[0,π/2]) is also observed. This linear dependence can also be a good approximation for the study of magnetic drug targeting, as in the human body the capillaries are of different sizes, and the externally applied magnetic field is not always parallel or perpendicular to the drug flow direction. PMID:22463326

  7. Predicting human blood viscosity in silico.

    PubMed

    Fedosov, Dmitry A; Pan, Wenxiao; Caswell, Bruce; Gompper, Gerhard; Karniadakis, George E

    2011-07-19

    The viscosity of blood has long been used as an indicator in the understanding and treatment of disease, and the advent of modern viscometers allows its measurement with ever-improving clinical convenience. However, these advances have not been matched by theoretical developments that can yield a quantitative understanding of blood's microrheology and its possible connection to relevant biomolecules (e.g., fibrinogen). Using coarse-grained molecular dynamics and two different red blood cell models, we accurately predict the dependence of blood viscosity on shear rate and hematocrit. We explicitly represent cell-cell interactions and identify the types and sizes of reversible rouleaux structures that yield a tremendous increase of blood viscosity at low shear rates. We also present the first quantitative estimates of the magnitude of adhesive forces between red cells. In addition, our simulations support the hypothesis, previously deduced from experiments, of yield stress as an indicator of cell aggregation. This non-Newtonian behavior is analyzed and related to the suspension's microstructure, deformation, and dynamics of single red blood cells. The most complex cell dynamics occurs in the intermediate shear rate regime, where individual cells experience severe deformation and transient folded conformations. The generality of these cell models together with single-cell measurements points to the future prediction of blood-viscosity anomalies and the corresponding microstructures associated with various diseases (e.g., malaria, AIDS, and diabetes mellitus). The models can easily be adapted to tune the properties of a much wider class of complex fluids including capsule and vesicle suspensions. PMID:21730178

  8. RELAP-7 Numerical Stabilization: Entropy Viscosity Method

    SciTech Connect

    R. A. Berry; M. O. Delchini; J. Ragusa

    2014-06-01

    The RELAP-7 code is the next generation nuclear reactor system safety analysis code being developed at the Idaho National Laboratory (INL). The code is based on the INL's modern scientific software development framework, MOOSE (Multi-Physics Object Oriented Simulation Environment). The overall design goal of RELAP-7 is to take advantage of the previous thirty years of advancements in computer architecture, software design, numerical integration methods, and physical models. The end result will be a reactor systems analysis capability that retains and improves upon RELAP5's capability and extends the analysis capability for all reactor system simulation scenarios. RELAP-7 utilizes a single phase and a novel seven-equation two-phase flow models as described in the RELAP-7 Theory Manual (INL/EXT-14-31366). The basic equation systems are hyperbolic, which generally require some type of stabilization (or artificial viscosity) to capture nonlinear discontinuities and to suppress advection-caused oscillations. This report documents one of the available options for this stabilization in RELAP-7 -- a new and novel approach known as the entropy viscosity method. Because the code is an ongoing development effort in which the physical sub models, numerics, and coding are evolving, so too must the specific details of the entropy viscosity stabilization method. Here the fundamentals of the method in their current state are presented.

  9. Vapor-phase viscosity of phenol

    NASA Astrophysics Data System (ADS)

    Vogel, E.; Neumann, A.-K.

    1993-07-01

    New measurements of the vapor-phase viscosity of phenol were performed from 437 up to 624 K and for densities between 0.006 and 0.023 mol · L-1 in an all-quartz oscillating-disk viscometer with small gaps. Thus, including our own measurements reported earlier, experimental data are available in the temperature range between 376 and 639 K and in the density range from 0.001 up to 0.023 mol · L-1. The data were evaluated with a density series for the viscosity in which only a linear density contribution is included. The values of the second viscosity virial coefficient obtained for phenol as well as for benzene, toluene, and p-xylene were compared with results of the Rainwater-Friend theory and of the modified Enskog theory on the basis of the Lennard-Jones 12-6 potential. The agreement is reasonable, when the potential parameter ratios determined by Bich and Vogel are used. The influence of bound dimers seems to be already taken into account in the three-monomer contribution according to Hoffman and Curtiss.

  10. Turbulent viscosity in natural surf zones

    NASA Astrophysics Data System (ADS)

    Grasso, F.; Ruessink, B. G.

    2012-12-01

    Waves breaking in the shallow surf zone near the shoreline inject turbulence into the water column that may reach the bed to suspend sediment. Breaking-wave turbulence in the surf zone is, however, poorly understood, which is one of the reasons why many process-based coastal-evolution models predict coastal change during severe storms inadequately. Here, we use data collected in two natural surf zones to derive a new parameterization for the stability function Cμ that determines the magnitude of the eddy viscosity νt in two-equation turbulent-viscosity models, νt = Cμk2/ε, where k is turbulent kinetic energy and ε is the turbulence dissipation rate. In both data sets, the ratio of turbulence production to dissipation is small (≈0.15), while vertical turbulence diffusion is significant. This differs from assumptions underlying existing Cμ parameterizations, which we show to severely overpredict observed Cμ for most conditions. Additionally, we rewrite our new Cμ parameterization into a formulation that accurately reproduces our Reynolds-stress based estimates of turbulence production. This formulation is linear with strain, consistent with earlier theoritical work for large strain rates. Also, it does not depend on ε and can, therefore, also be applied in one-equation turbulent-viscosity models. We anticipate our work to improve turbulence modeling in natural surf zones and to eventually lead to more reliable predictions of coastal evolution in response to severe storms.

  11. Anisotropic Shear Viscosity of Photoaligned Liquid Crystal Confined in Submicrometer-to-Nanometer-Scale Gap Widths Revealed with Simultaneously Measured Molecular Orientation.

    PubMed

    Itoh, Shintaro; Imura, Yuuichi; Fukuzawa, Kenji; Zhang, Hedong

    2015-10-20

    In the context of the use of liquid crystals (LCs) as lubricants and lubricant additives, this study investigates the anisotropic shear viscosity of LCs confined in nanometer-sized gap widths subject to both shearing and photoalignment. The photoalignment is achieved using anisotropically dimerized polyvinyl cinnamate (PVCi) films coated on substrates. We simultaneously measure the viscosity and order parameter of a liquid crystal (4-cyano-4'-pentylbiphenyl) confined and sheared in the gap range of 500 nm down to a few nm. We achieve this simultaneous measurement using an original method that combines a highly sensitive viscosity measurement and a sensitive birefringence measurement. When the LC is sheared in the same direction as the photoalignment (parallel shearing), the order parameter, which is around 0.3 in the bulk state, increases up to around 0.4 at a gap width of less than 50 nm and the viscosity is smaller than half the bulk viscosity. We consider that this increase in the order parameter is due to the highly ordered photoaligned LC layer near the PVCi film, and the viscosity decrease is due to shear thinning of this layer enhanced by both confinement and molecular ordering. In addition, we observe a gradual decrease in viscosity starting at a gap of less than around 300 nm in the parallel shearing. Based on the apparent slip model, we show that the LC layer near the PVCi film can also cause this gradual viscosity decrease. In contrast, when the LC is sheared in the direction perpendicular to the photoalignment direction (perpendicular shearing), the viscosity increases as the gap decreases. We speculate that this is due to the rotational motion of the LC molecules caused by the competing effect of shear alignment and photoalignment. We believe our findings can significantly contribute to a better understanding of the confined LCs utilized for lubrication. PMID:26401898

  12. Driving and neurodegenerative diseases.

    PubMed

    Uc, Ergun Y; Rizzo, Matthew

    2008-09-01

    The proportion of elderly people in the general population is rising, resulting in greater numbers of drivers with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. These neurodegenerative disorders impair cognition, visual perception, and motor function, leading to reduced driver fitness and greater crash risk. Yet neither medical diagnosis nor age alone is reliable enough to predict driver safety or crashes or to revoke the driving privileges of these individuals. Driving research utilizes tools such as questionnaires about driving habits and history, driving simulators, standardized road tests utilizing instrumented vehicles, and state driving records. Research challenges include outlining the evolution of driving safety, understanding the mechanisms of driving impairment, and developing a reliable and efficient standardized test battery for prediction of driver safety in neurodegenerative disorders. This information will enable healthcare providers to advise their patients with neurodegenerative disorders with more certainty, affect policy, and help develop rehabilitative measures for driving. PMID:18713573

  13. Gear bearing drive

    NASA Technical Reports Server (NTRS)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  14. Reference Correlation for the Viscosity of Ethane

    SciTech Connect

    Vogel, Eckhard; Span, Roland; Herrmann, Sebastian

    2015-12-15

    A new representation of the viscosity for the fluid phase of ethane includes a zero-density correlation and a contribution for the critical enhancement, initially both developed separately, but based on experimental data. The higher-density contributions are correlated as a function of the reduced density δ = ρ/ρ{sub c} and of the reciprocal reduced temperature τ = T{sub c}/T (ρ{sub c}—critical density and T{sub c}—critical temperature). The final formulation contains 14 coefficients obtained using a state-of-the-art linear optimization algorithm. The evaluation and choice of the selected primary data sets is reviewed, in particular with respect to the assessment used in earlier viscosity correlations. The new viscosity surface correlation makes use of the reference equation of state for the thermodynamic properties of ethane by Bücker and Wagner [J. Phys. Chem. Ref. Data 35, 205 (2006)] and is valid in the fluid region from the melting line to temperatures of 675 K and pressures of 100 MPa. The viscosity in the limit of zero density is described with an expanded uncertainty of 0.5% (coverage factor k = 2) for temperatures 290 < T/K < 625, increasing to 1.0% at temperatures down to 212 K. The uncertainty of the correlated values is 1.5% in the range 290 < T/K < 430 at pressures up to 30 MPa on the basis of recent measurements judged to be very reliable as well as 4.0% and 6.0% in further regions. The uncertainty in the near-critical region (1.001 < 1/τ < 1.010 and 0.8 < δ < 1.2) increases with decreasing temperature up to 3.0% considering the available reliable data. Tables of the viscosity calculated from the correlation are listed in an appendix for the single-phase region, for the vapor–liquid phase boundary, and for the near-critical region.

  15. Magnetic drive coupling

    NASA Technical Reports Server (NTRS)

    Carter, Edward L. (Inventor)

    1987-01-01

    The driving and driven members of a magnetic drive are separated by en enlarged gap to provide clearance for a conduit or other member. Flux pins in the gap maintain the torque transmitting capability of the drive. The spacing between two of the flux pins is increased to provide space for the conduit.

  16. Magnetic drive coupling

    NASA Technical Reports Server (NTRS)

    Carter, Edward L. (Inventor)

    1989-01-01

    The driving (30) and driven (32) members of a magnetic drive (20) are separated by an enlarged gap (35) to provide clearance for a conduit (23) or other member. Flux pins (40) in the gap (35) maintain the torque transmitting capability of the drive (20). The spacing between two of the flux pins is increased to provide space for the conduit (23).

  17. Sequential Dependencies in Driving

    ERIC Educational Resources Information Center

    Doshi, Anup; Tran, Cuong; Wilder, Matthew H.; Mozer, Michael C.; Trivedi, Mohan M.

    2012-01-01

    The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find…

  18. Grieving while Driving

    ERIC Educational Resources Information Center

    Rosenblatt, Paul C.

    2004-01-01

    Secondary analysis of data from 84 people in 2 interview studies shows that some bereaved people grieve actively while driving. The grief can be intense, even years after a death. Grief while driving may erupt spontaneously or be set off by a wide range of reminders. Some bereaved people seem to save their grieving for times when they drive,…

  19. Flow fields in soap films: Relating viscosity and film thickness

    NASA Astrophysics Data System (ADS)

    Prasad, V.; Weeks, Eric R.

    2009-08-01

    We follow the diffusive motion of colloidal particles in soap films with varying h/d , where h is the thickness of the film and d is the diameter of the particles. The hydrodynamics of these films are determined by looking at the correlated motion of pairs of particles as a function of separation R . The Trapeznikov approximation [A. A. Trapeznikov, Proceedings of the 2nd International Congress on Surface Activity (Butterworths, London, 1957), p. 242] is used to model soap films as an effective two-dimensional (2D) fluid in contact with bulk air phases. The flow fields determined from correlated particle motions show excellent agreement with what is expected for the theory of 2D fluids for all our films where 0.6≤h/d≤14.3 , with the 2D shear viscosity matching that predicted by Trapeznikov. However, the parameters of these flow fields change markedly for thick films (h/d>7±3) . Our results indicate that three-dimensional effects become important for these thicker films, despite the flow fields still having a 2D character.

  20. The Role of Viscosity in TATB Hot Spot Ignition

    SciTech Connect

    Fried, L E; Zepeda-Ruis, L; Howard, W M; Najjar, F; Reaugh, J E

    2011-08-02

    The role of dissipative effects, such as viscosity, in the ignition of high explosive pores is investigated using a coupled chemical, thermal, and hydrodynamic model. Chemical reactions are tracked with the Cheetah thermochemical code coupled to the ALE3D hydrodynamic code. We perform molecular dynamics simulations to determine the viscosity of liquid TATB. We also analyze shock wave experiments to obtain an estimate for the shock viscosity of TATB. Using the lower bound liquid-like viscosities, we find that the pore collapse is hydrodynamic in nature. Using the upper bound viscosity from shock wave experiments, we find that the pore collapse is closest to the viscous limit.

  1. The role of viscosity in TATB hot spot ignition

    NASA Astrophysics Data System (ADS)

    Fried, Laurence E.; Zepeda-Ruis, Luis; Howard, W. Michael; Najjar, Fady; Reaugh, John E.

    2012-03-01

    The role of dissipative effects, such as viscosity, in the ignition of high explosive pores is investigated using a coupled chemical, thermal, and hydrodynamic model. Chemical reactions are tracked with the Cheetah thermochemical code coupled to the ALE3D hydrodynamic code. We perform molecular dynamics simulations to determine the viscosity of liquid TATB. We also analyze shock wave experiments to obtain an estimate for the shock viscosity of TATB. Using the lower bound liquid-like viscosities, we find that the pore collapse is hydrodynamic in nature. Using the upper bound viscosity from shock wave experiments, we find that the pore collapse is closest to the viscous limit.

  2. Reduction of viscosity in suspension of swimming bacteria.

    SciTech Connect

    Aranson, I. S.; Sokolov, A.; Chen, L.; Jin, Q.; Materials Science Division

    2009-09-29

    Measurements of the shear viscosity in suspensions of swimming Bacillus subtilis in free-standing liquid films have revealed that the viscosity can decrease by up to a factor of 7 compared to the viscosity of the same liquid without bacteria or with nonmotile bacteria. The reduction in viscosity is observed in two complementary experiments: one studying the decay of a large vortex induced by a moving probe and another measuring the viscous torque on a rotating magnetic particle immersed in the film. The viscosity depends on the concentration and swimming speed of the bacteria.

  3. Reduction of viscosity in suspension of swimming bacteria.

    SciTech Connect

    Sokolov, A.; Aranson, I. S.; Materials Science Division; Illinois Inst. of Tech.

    2009-01-01

    Measurements of the shear viscosity in suspensions of swimming Bacillus subtilis in free-standing liquid films have revealed that the viscosity can decrease by up to a factor of 7 compared to the viscosity of the same liquid without bacteria or with nonmotile bacteria. The reduction in viscosity is observed in two complementary experiments: one studying the decay of a large vortex induced by a moving probe and another measuring the viscous torque on a rotating magnetic particle immersed in the film. The viscosity depends on the concentration and swimming speed of the bacteria.

  4. Viscosity and stability of ultra-high internal phase CO2-in-water foams stabilized with surfactants and nanoparticles with or without polyelectrolytes.

    PubMed

    Xue, Zheng; Worthen, Andrew; Qajar, Ali; Robert, Isaiah; Bryant, Steven L; Huh, Chun; Prodanović, Maša; Johnston, Keith P

    2016-01-01

    To date, relatively few examples of ultra-high internal phase supercritical CO2-in-water foams (also referred to as macroemulsions) have been observed, despite interest in applications including "waterless" hydraulic fracturing in energy production. The viscosities and stabilities of foams up to 0.98 CO2 volume fraction were investigated in terms of foam bubble size, interfacial tension, and bulk and surface viscosity. The foams were stabilized with laurylamidopropyl betaine (LAPB) surfactant and silica nanoparticles (NPs), with and without partially hydrolyzed polyacrylamide (HPAM). For foams stabilized with mixture of LAPB and NPs, fine ∼70 μm bubbles and high viscosities on the order of 100 cP at>0.90 internal phase fraction were stabilized for hours to days. The surfactant reduces interfacial tension, and thus facilitates bubble generation and decreases the capillary pressure to reduce the drainage rate of the lamella. The LAPB, which is in the cationic protonated form, also attracts anionic NPs (and anionic HPAM in systems containing polymer) to the interface. The adsorbed NPs at the interface are shown to slow down Ostwald ripening (with or without polymer added) and increase foam stability. In systems with added HPAM, the increase in the bulk and surface viscosity of the aqueous phase further decreases the lamella drainage rate and inhibits coalescence of foams. Thus, the added polymer increases the foam viscosity by threefold. Scaling law analysis shows the viscosity of 0.90 volume fraction foams is inversely proportional to the bubble size. PMID:26414421

  5. Extensional Flow of Bulk Polymers

    NASA Technical Reports Server (NTRS)

    Peng, T. J.

    1972-01-01

    A study was made of the behavior of polyisobutylene under motion at a constant stretch history for both strip biaxial extensional flow and simple extensional flow. Steady-state non-Newtonian viscosities were observed at various constant stretch histories. Newtonian viscosities for both strip biaxial and simple extensional flow were found to be in agreement with the classical theory. The results of the study provide an essential part of the experimental background necessary for the development of a new general stress-strain-time relation for uncrosslinked and lightly crosslinked polymers.

  6. Electric versus hydraulic drives

    SciTech Connect

    Not Available

    1983-01-01

    This volume records the proceedings of a conference organised by the Engineering Manufacturing Industries Division of the Institution of Mechanical Engineers. Topics considered include high performance position control - a review of the current state of developments; hydrostatic drives - present and future; electric drives - present and future trends; electrical and hydraulic drives for heavy industrial robots; the development of an electro-mechanical tilt system for the advanced passenger train; industrial hydraulic ring mains - effective or efficient. the comparison of performance of servo feed-drive systems; overhead crane drives; the future of d.c. servodrives; the choice of actuator for military systems; linear electro-hydraulic actuators; and actuation for industrial robots.

  7. Bulk Data Mover

    SciTech Connect

    2011-01-03

    Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections, data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/

  8. "Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

    NASA Astrophysics Data System (ADS)

    Marshall, J. R.

    1999-09-01

    very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion

  9. "Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.

    1999-01-01

    very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion

  10. Electron treatment of wood pulp for the viscose process

    NASA Astrophysics Data System (ADS)

    Stepanik, T. M.; Ewing, D. E.; Whitehouse, R.

    2000-03-01

    Electron processing is currently being evaluated by several viscose producers for integration into their process. The viscose industry converts dissolving wood pulp into products such as staple fibre, filament, cord, film, packaging, and non-edible sausage casings. These materials are used in the clothing, drapery, hygiene, automobile, food, and packaging industries. Viscose producers are facing increasingly high production costs and stringent environmental regulations that have forced some plants to close. Electron treatment of wood pulp can significantly reduce the amounts of chemicals used for producing viscose and the production of hazardous pollutants. Acsion Industries has worked with companies worldwide to demonstrate the benefits of using electron treated pulp for producing viscose (rayon). This paper describes the viscose process, the benefits of using electron treatment in the viscose process, and Acsion's efforts in developing this technology.

  11. "Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.

    1999-01-01

    very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion

  12. Drill drive mechanism

    DOEpatents

    Dressel, Michael O.

    1979-01-01

    A drill drive mechanism is especially adapted to provide both rotational drive and axial feed for a drill of substantial diameter such as may be used for drilling holes for roof bolts in mine shafts. The drill shaft is made with a helical pattern of scroll-like projections on its surface for removal of cuttings. The drill drive mechanism includes a plurality of sprockets carrying two chains of drive links which are arranged to interlock around the drill shaft with each drive link having depressions which mate with the scroll-like projections. As the chain links move upwardly or downwardly the surfaces of the depressions in the links mate with the scroll projections to move the shaft axially. Tangs on the drive links mate with notch surfaces between scroll projections to provide a means for rotating the shaft. Projections on the drive links mate together at the center to hold the drive links tightly around the drill shaft. The entire chain drive mechanism is rotated around the drill shaft axis by means of a hydraulic motor and gear drive to cause rotation of the drill shaft. This gear drive also connects with a differential gearset which is interconnected with a second gear. A second motor is connected to the spider shaft of the differential gearset to produce differential movement (speeds) at the output gears of the differential gearset. This differential in speed is utilized to drive said second gear at a speed different from the speed of said gear drive, this speed differential being utilized to drive said sprockets for axial movement of said drill shaft.

  13. A transport equation for eddy viscosity

    NASA Technical Reports Server (NTRS)

    Durbin, P. A.; Yang, Z.

    1992-01-01

    A transport equation for eddy viscosity is proposed for wall bounded turbulent flows. The proposed model reduces to a quasi-homogeneous form far from surfaces. Near to a surface, the nonhomogeneous effect of the wall is modeled by an elliptic relaxation model. All the model terms are expressed in local variables and are coordinate independent; the model is intended to be used in complex flows. Turbulent channel flow and turbulent boundary layer flows with/without pressure gradient are calculated using the present model. Comparisons between model calculations and direct numerical simulation or experimental data show good agreement.

  14. Viscosity in the edge of tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Stacey, W. M.

    1993-05-01

    A fluid representation of viscosity has been incorporated into a set of fluid equations that are maximally ordered in the 'short radial gradient scale length' (srgsl) ordering that is appropriate for the edge of tokamak plasmas. The srgsl ordering raises viscous drifts and other viscous terms to leading order and fundamentally alters the character of the fluid equations. A leasing order viscous drift is identified. Viscous-driven radial particle and energy fluxes in the scrape-off layer and divertor channel are estimated to have an order unity effect in reducing radial peaking of energy fluxes transported along the field lines to divertor collector plates.

  15. On the measurement of magnetic viscosity

    NASA Astrophysics Data System (ADS)

    Serletis, C.; Efthimiadis, K. G.

    2012-08-01

    This work is an investigation of the experimental method used for measuring the magnetic viscosity in a hard ferromagnetic material, i.e. the recording of the magnetization under constant applied field and temperature, after the material has been magnetically saturated. It investigates how the experimental results are affected by the initial conditions of the method (saturation field, field change rate and field oscillation prior to its stabilization), and by minor variations of field and temperature during the recording. Based on the arising conclusions and the use of a more complex fitting function of measurements, the accuracy and repeatability of experimental results is improved.

  16. Phobos: Observed bulk properties

    NASA Astrophysics Data System (ADS)

    Pätzold, Martin; Andert, Tom; Jacobson, Robert; Rosenblatt, Pascal; Dehant, Véronique

    2014-11-01

    This work is a review of the mass determinations of the Mars moon Phobos by spacecraft close flybys, by solving for the Martian gravity field and by the analysis of secular orbit perturbations. The absolute value and accuracy is sensitive on the knowledge and accuracy of the Phobos ephemeris, of the spacecraft orbit, other perturbing forces acting on the spacecraft and the resolution of the Martian gravity field besides the measurement accuracy of the radio tracking data. The mass value and its error improved from spacecraft mission to mission or from the modern analysis of “old” tracking data but these solutions depend on the accuracy of the ephemeris at the time of observation. The mass value seems to settle within the range of GMPh=(7.11±0.09)×10-4 km3 s-2 which covers almost all mass values from close flybys and “distant” encounters within its 3-σ error (1.5%). Using the volume value determined from MEX HRSC imaging, the bulk density is (1873±31) kg m-3 (3-σ error or 1.7%), a low value which suggests that Phobos is either highly porous, is composed partially of light material or both. The determination of the gravity coefficients C20 and C22 from the Mars Express 2010 close flyby does not allow to draw conclusion on the internal structure. The large errors do not distinguish whether Phobos is homogeneous or not. In view of theories of the Phobos' origin, one possibility is that Phobos is not a captured asteroid but accreted from a debris disk in Mars orbit as a second generation solar system object.

  17. Bulk Data Mover

    Energy Science and Technology Software Center (ESTSC)

    2011-01-03

    Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections,more » data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/« less

  18. Magnetostrictive roller drive motor

    NASA Astrophysics Data System (ADS)

    Vranish, John M.

    1992-01-01

    A magnetostrictive drive motor is disclosed which has a rotary drive shaft in the form of a drum which is encircled by a plurality of substantially equally spaced roller members in the form of two sets of cones which are in contact with the respective cam surfaces on the inside surface of an outer drive ring. The drive ring is attached to sets of opposing pairs of magnetostrictive rods. Each rod in a pair is mutually positioned end to end within respective energizing coils. When one of the coils in an opposing pair is energized, the energized rod expands while the other rod is caused to contract, causing the drive ring to rock, i.e., rotate slightly in either the clockwise or counterclockwise direction, depending upon which rod in a pair is energized. As the drive ring is activated in repetitive cycles in either direction, one set of drive cones attempts to roll up their respective cam surface but are pinned between the drive shaft drum and the drive ring. As the frictional force preventing sliding builds up, the cones become locked, setting up reaction forces including a tangential component which is imparted to the drive shaft drum to provide a source of motor torque. Simultaneously the other set of cones are disengaged from the drive shaft drum. Upon deactivation of the magnetostrictive rod coils, the force on the drive cones is released, causing the system to return to an initial rest position. By repetitively cycling the energization of the magnetostrictive rods, the drive shaft drum indexes in microradian rotational steps.

  19. VISCOSITY IN PLANETARY RINGS WITH SPINNING SELF-GRAVITATING PARTICLES

    SciTech Connect

    Yasui, Yuki; Ohtsuki, Keiji; Daisaka, Hiroshi

    2012-05-15

    Using local N-body simulation, we examine viscosity in self-gravitating planetary rings. We investigate the dependence of viscosity on various parameters in detail, including the effects of particle surface friction. In the case of self-gravitating rings with low optical depth, viscosity is determined by particle random velocity. Inclusion of surface friction slightly reduces both random velocity and viscosity when particle random velocity is determined by inelastic collisions, while surface friction slightly increases viscosity when gravitational encounters play a major role in particle velocity evolution, so that viscous heating balances with increased energy dissipation at collisions due to surface friction. We find that including surface friction changes viscosity in dilute rings up to a factor of about two. In the case of self-gravitating dense rings, viscosity is significantly increased due to the effects of gravitational wakes, and we find that varying restitution coefficients also change viscosity in such dense rings by a factor of about two. We confirm that our numerical results for viscosity in dense rings with gravitational wakes can be well approximated by a semianalytic expression that is consistent with a previously obtained formula. However, we find that this formula seems to overestimate viscosity in dense rings far from the central planet, where temporary gravitational aggregates form. We derive semianalytic expressions that reproduce our numerical results well for the entire range of examined parameters.

  20. Methods of Viscosity Measurements in Sealed Ampoules

    NASA Technical Reports Server (NTRS)

    Mazuruk, Konstantin

    1999-01-01

    Viscosity of semiconductor and metallic melts is usually measured by oscillating cup method. This method utilizes the melts contained in vacuum sealed silica ampoules, thus the problems related to volatility, contamination, and high temperature and pressure can be alleviated. In a typical design, the time required for a single measurement is of the order of one hour. In order to reduce this time to a minute range, a high resolution (0.05 arc.sec) angular detection system is implemented in our design of the viscometer. Furthermore, an electromagnet generating a rotational magnetic field (RMF) is incorporated into the apparatus. This magnetic field can be used to remotely and non intrusively measure the electrical conductivity of the melt. It can also be used to induce a well controlled rotational flow in the system. The transient behavior of this flow can potentially yield the viscosity of the fluid. Based on RMF implementation, two novel viscometry methods are proposed in this work: a) the transient torque method, b) the resonance method. A unified theoretical approach to the three methods (oscillating cup, transient torque, and resonance) is presented along with the initial test results of the constructed apparatus. Advantages of each of the method are discussed.

  1. Critical viscosity exponent for classical fluids

    NASA Astrophysics Data System (ADS)

    Hao, Hong; Ferrell, Richard A.; Bhattacharjee, Jayanta K.

    2005-02-01

    A self-consistent mode-coupling calculation of the critical viscosity exponent zη for classical fluids is performed by including the memory effect and the vertex corrections. The incorporation of the memory effect is through a self-consistency procedure that evaluates the order parameter and shear momentum relaxation rates at nonzero frequencies, thereby taking their frequency dependence into account. This approach offers considerable simplification and efficiency in the calculation. The vertex corrections are also demonstrated to have significant effects on the numerical value for the critical viscosity exponent, in contrast to some previous theoretical work which indicated that the vertex corrections tend to cancel out from the final result. By carrying out all of the integrations analytically, we have succeeded in tracing the origin of this discrepancy to an error in earlier work. We provide a thorough treatment of the two-term epsilon expansion, as well as a complete three-dimensional analysis of the fluctuating order-parameter and transverse hydrodynamic modes. The study of the interactions of these modes is carried out to high order so as to arrive at zη=0.0679±0.0007 for comparison with the experimentally observed value, 0.0690±0.0006 .

  2. Enhancing some functional properties of viscose fabric.

    PubMed

    Fahmy, H M; Eid, R A A; Hashem, S S; Amr, A

    2013-02-15

    To enhance the functional properties of viscose fabrics, Tinosan(®) CEL (TC), Ag, and TiO(2) nano-particles were incorporated as functional additives in different easy care finishing formulations alone and in admixtures. Results indicated that padding viscose fabrics in finishing bath containing 10 g/l TC and 60 g/l dimethyloldihydroxyethylene urea (DMDHEU) enhances some performance as well as antibacterial properties of the treated fabrics. Moreover, incorporation of Ag or TiO(2) nano-particles in the DMDHEU or DMDHEU/TC finishing baths enhances the functional properties of the treated samples such as antibacterial properties, UV-blocking properties, and/or self cleaning performance. Incorporation of poly (N-vinyl-2-pyrrolidone) in the aforementioned finishing formulations enhances these functional properties along with durability to wash. On the other hand, incorporation of Silicon(®)-SLH softener in finishing baths along with TC affects the performance and antibacterial properties of the treated fabrics. PMID:23399186

  3. The intrinsic viscosity of linear DNA.

    PubMed

    Tsortos, Achilleas; Papadakis, George; Gizeli, Electra

    2011-12-01

    We measured the intrinsic viscosity of very small synthetic DNA molecules, of 20-395 base pairs, and incorporated them in a nearly complete picture for the whole span of molecular weights reported in the literature to date. A major transition is observed at M approximately 2 × 10(6) . It is found that in the range of approximately 7 × 10(3) ≤ M ≤ 2 × 10(6) , the intrinsic viscosity scales as [η] approximately M(1.05) , suggesting that short DNA chains are not as rigid as generally thought. The corresponding scaling for the range of 2 × 10(6) ≤ M ≤ 8 × 10(10) is [η] approximately M(0.69) . A comparison of our results with existing equations, for much narrower data distributions, is made, and the agreement is very satisfactory considering the huge range of data analyzed here. Experimental concerns such as the effect of ionic strength, polydispersity, temperature, and shear rate are discussed in detail. Some issues concerning the Huggins coefficient, polymer chain stiffness, and the relationship between the Mark-Houwink constants K, α are also presented; it is found that log K = 1.156 - 6.19α. PMID:21638275

  4. Predicting human blood viscosity in silico

    SciTech Connect

    Fedosov, Dmitry A.; Pan, Wenxiao; Caswell, Bruce; Gompper, Gerhard; Karniadakis, George E.

    2011-07-05

    Cellular suspensions such as blood are a part of living organisms and their rheological and flow characteristics determine and affect majority of vital functions. The rheological and flow properties of cell suspensions are determined by collective dynamics of cells, their structure or arrangement, cell properties and interactions. We study these relations for blood in silico using a mesoscopic particle-based method and two different models (multi-scale/low-dimensional) of red blood cells. The models yield accurate quantitative predictions of the dependence of blood viscosity on shear rate and hematocrit. We explicitly model cell aggregation interactions and demonstrate the formation of reversible rouleaux structures resulting in a tremendous increase of blood viscosity at low shear rates and yield stress, in agreement with experiments. The non-Newtonian behavior of such cell suspensions (e.g., shear thinning, yield stress) is analyzed and related to the suspension’s microstructure, deformation and dynamics of single cells. We provide the flrst quantitative estimates of normal stress differences and magnitude of aggregation forces in blood. Finally, the flexibility of the cell models allows them to be employed for quantitative analysis of a much wider class of complex fluids including cell, capsule, and vesicle suspensions.

  5. Evaluation of cervical marginal and internal adaptation using newer bulk fill composites: An in vitro study

    PubMed Central

    Agarwal, Rolly Shrivastav; Hiremath, Hemlatha; Agarwal, Jatin; Garg, Ashish

    2015-01-01

    Objective: To evaluate the cervical marginal and internal adaptation of posterior bulk fill resin composites of different viscosities, before and after thermo-cycling (TMC). Materials and Methods: Eighty box-only class II cavities were prepared in 40 extracted human premolars with the distal proximal box beneath the enamel-cementum junction (CEJ). The teeth in the experimental groups were restored with bulk fill resin composite restorations (Gr. I- Sonic Fill, Gr. II- SDR, Gr. III- Tetric N Ceram Bulk Fill or a conventional composite designed for 2-mm increments (Gr. IV- Tetric N Flow along with Tetric N Ceram). Before and after thermal cycling, the gap-free marginal length was analyzed using SEM of epoxy resin replicas. After thermal cycling, specimens were cut longitudinally in order to investigate internal dentine adaptation by epoxy replicas under SEM (500 × magnification). Results: Statistical analysis was performed using the ANOVA and Tukey Post Hoc tests (P < 0.05). In enamel, high percentages of gap-free margins were initially identified for all the groups, which declined after thermal cycling. However, no significant differences were identified among any of the groups (P > 0.05). In dentine, bulk fill groups performed at par with the incremental placement; for both marginal and internal adaptation (P < 0.05), for all materials except Tetric N Ceram Bulk Fill. Conclusions: Viscosity of the bulk fill restorative material influenced the proportion of gap-free marginal interface and the internal adaptation in dentin. PMID:25657529

  6. Combustion of bulk titanium in oxygen

    NASA Technical Reports Server (NTRS)

    Clark, A. F.; Moulder, J. C.; Runyan, C. C.

    1975-01-01

    The combustion of bulk titanium in one atmosphere oxygen is studied using laser ignition and several analytical techniques. These were high-speed color cinematography, time and space resolved spectra in the visible region, metallography (including SEM) of specimens quenched in argon gas, X-ray and chemical product analyses, and a new optical technique, the Hilbert transform method. The cinematographic application of this technique for visualizing phase objects in the combustion zone is described. The results indicate an initial vapor phase reaction immediately adjacent to the molten surface but as the oxygen uptake progresses the evaporation approaches the point of congruency and a much reduced evaporation rate. This and the accumulation of the various soluble oxides soon drive the reaction zone below the surface where gas formation causes boiling and ejection of particles. The buildup of rutile cuts off the oxygen supply and the reaction ceases.

  7. Superluminal warp drive

    NASA Astrophysics Data System (ADS)

    González-Díaz, Pedro F.

    2007-09-01

    In this Letter we consider a warp drive spacetime resulting from that suggested by Alcubierre when the spaceship can only travel faster than light. Restricting to the two dimensions that retains most of the physics, we derive the thermodynamic properties of the warp drive and show that the temperature of the spaceship rises up as its apparent velocity increases. We also find that the warp drive spacetime can be exhibited in a manifestly cosmological form.

  8. Soy protein isolate molecular level contributions to bulk adhesive properties

    NASA Astrophysics Data System (ADS)

    Shera, Jeanne Norton

    Increasing environmental awareness and the recognized health hazards of formaldehyde-based resins has prompted a strong demand for environmentally-responsible adhesives for wood composites. Soy protein-based adhesives have been shown to be commercially viable with 90-day shelf stability and composite physical properties comparable to those of commercial formaldehyde-based particleboards. The main research focus is to isolate and characterize the molecular level features in soy protein isolate responsible for providing mechanical properties, storage stability, and water resistance during adhesive formulation, processing, and wood composite fabrication. Commercial composite board will be reviewed to enhance our understanding of the individual components and processes required for particleboard production. The levels of protein structure will be defined and an overview of current bio-based technology will be presented. In the process, the logic for utilizing soy protein as a sole binder in the adhesive will be reinforced. Variables such as adhesive components, pH, divalent ions, blend aging, protein molecular weight, formulation solids content, and soy protein functionalization will relate the bulk properties of soy protein adhesives to the molecular configuration of the soybean protein. This work has demonstrated that when intermolecular beta-sheet interactions and protein long-range order is disrupted, viscosity and mechanical properties decrease. Storage stability can be maintained through the stabilization of intermolecular beta-sheet interactions. When molecular weight is reduced through enzymatic digestion, long-range order is disrupted and viscosity and mechanical properties decrease accordingly. Processibility and physical properties must be balanced to increase solids while maintaining low viscosity, desirable mechanical properties, and adequate storage stability. The structure of the soybean protein must be related to the particleboard bulk mechanical

  9. Diabetes and driving.

    PubMed

    Inkster, B; Frier, B M

    2013-09-01

    The principal safety concern for driving for people treated with insulin or insulin secretagogues is hypoglycaemia, which impairs driving performance. Other complications, such as those causing visual impairment and peripheral neuropathy, are also relevant to medical fitness to drive. Case control studies have suggested that drivers with diabetes pose a modestly increased but acceptable and measurable risk of motor vehicle accidents compared to non-diabetic drivers, but many studies are limited and of poor quality. Factors which have been shown to increase driving risk include previous episodes of severe hypoglycaemia, previous hypoglycaemia while driving, strict glycaemic control (lower HbA1c) and absence of blood glucose monitoring before driving. Impaired awareness of hypoglycaemia may be counteracted by frequent blood glucose testing. The European Union Third directive on driving (2006) has necessitated changes in statutory regulations for driving licences for people with diabetes in all European States, including the UK. Stricter criteria have been introduced for Group 1 vehicle licences while those for Group 2 licences have been relaxed. Insulin-treated drivers can now apply to drive Group 2 vehicles, but in the UK must meet very strict criteria and be assessed by an independent specialist to be issued with a 1-year licence. PMID:23350766

  10. Analytical Sensor Response Function of Viscosity Sensors Based on Layered Piezoelectric Thickness Shear Resonators

    NASA Astrophysics Data System (ADS)

    Benes, Ewald; Nowotny, Helmut; Braun, Stefan; Radel, Stefan; Gröschl, Martin

    Resonant piezoelectric sensors based on bulk acoustic wave (BAW) thickness shear resonators are promising for the inline measurement of fluid viscosity, e.g., in industrial processes. The sensor response function can be derived from the general rigorous transfer matrix description of one-dimensional layered structures consisting of piezoelectric and non-piezoelectric layers of arbitrary number. This model according to Nowotny et al. provides a complete analytical description of the electrical and mechanical behaviour of such structures with two electrodes and arbitrary acoustic termination impedances (Rig-1d-Model). We apply this model to derive the sensor response functions and the mechanical displacement curves of the following configurations appropriate for viscosity sensors: An AT cut quartz crystal plate in contact with vacuum at the backside plane and with the liquid under investigation at the front side plane (QL). An AT cut quartz crystal in contact with the liquid under investigation at both sides (LQL). It is shown that in the QL case the originally only heuristically introduced and well established sensor response function according to Kanasawa can be derived from the Rig-1d-Model by introducing minor approximations. Experimental results are presented for the LQL configuration using an N1000 viscosity reference oil as test fluid.

  11. Does seminal fluid viscosity influence sperm chromatin integrity?

    PubMed

    Gopalkrishnan, K; Padwal, V; Balaiah, D

    2000-01-01

    A retrospective study was undertaken to investigate whether viscosity alters sperm chromatin integrity. Semen samples were obtained from 269 men attending the infertility clinic. The viscosity was measured quantitatively by needle and syringe method and the viscosity ratio was calculated against distilled water. The chromatin integrity was evaluated by in vitro decondensation test using 1% SDS and 6 mM EDTA. According to the viscosity ratios the samples were divided into 2 groups: I, normal (ratio < 9, n = 239): and II, abnormal (ratio > 9, n = 30) viscosity. Chromatin integrity was significantly lower in the group with higher viscosity. Significant decrease in sperm count and motility were seen in group II as compared to group I. Thus, hyperviscosity of seminal fluid alters the sperm chromatin integrity. PMID:11028927

  12. Isomorphic Viscosity Equation of State for Binary Fluid Mixtures.

    PubMed

    Behnejad, Hassan; Cheshmpak, Hashem; Jamali, Asma

    2015-01-01

    The thermodynamic behavior of the simple binary mixtures in the vicinity of critical line has a universal character and can be mapped from pure components using the isomorphism hypothesis. Consequently, based upon the principle of isomorphism, critical phenomena and similarity between P-ρ-T and T-η-(viscosity)-P relationships, the viscosity model has been developed adopting two cubic, Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR), equations of state (EsoS) for predicting the viscosity of the binary mixtures. This procedure has been applied to the methane-butane mixture and predicted its viscosity data. Reasonable agreement with the experimental data has been observed. In conclusion, we have shown that the isomorphism principle in conjunction with the mapped viscosity EoS suggests a reliable model for calculating the viscosity of mixture of hydrocarbons over a wide pressure range up to 35 MPa within the stated experimental errors. PMID:26680701

  13. Dependence of neoclassical toroidal viscosity on the poloidal spectrum of applied nonaxisymmetric fields

    NASA Astrophysics Data System (ADS)

    Logan, N. C.; Park, J.-K.; Paz-Soldan, C.; Lanctot, M. J.; Smith, S. P.; Burrell, K. H.

    2016-03-01

    This paper presents a single mode model that accurately predicts the coupling of applied nonaxisymmetric fields to the plasma response that induces neoclassical toroidal viscosity (NTV) torque in DIII-D H-mode plasmas. The torque is measured and modeled to have a sinusoidal dependence on the relative phase of multiple nonaxisymmetric field sources, including a minimum in which large amounts of nonaxisymmetric drive is decoupled from the NTV torque. This corresponds to the coupling and decoupling of the applied field to a NTV-driving mode spectrum. Modeling using the perturbed equilibrium nonambipolar transport (PENT) code confirms an effective single mode coupling between the applied field and the resultant torque, despite its inherent nonlinearity. The coupling to the NTV mode is shown to have a similar dependence on the relative phasing as that of the IPEC dominant mode, providing a physical basis for the efficacy of this linear metric in predicting error field correction optima in NTV dominated regimes.

  14. Enhancing bulk superconductivity by engineering granular materials

    NASA Astrophysics Data System (ADS)

    Mayoh, James; García García, Antonio

    2014-03-01

    The quest for higher critical temperatures is one of the main driving forces in the field of superconductivity. Recent theoretical and experimental results indicate that quantum size effects in isolated nano-grains can boost superconductivity with respect to the bulk limit. Here we explore the optimal range of parameters that lead to an enhancement of the critical temperature in a large three dimensional array of these superconducting nano-grains by combining mean-field, semiclassical and percolation techniques. We identify a broad range of parameters for which the array critical temperature, TcArray, can be up to a few times greater than the non-granular bulk limit, Tc 0. This prediction, valid only for conventional superconductors, takes into account an experimentally realistic distribution of grain sizes in the array, charging effects, dissipation by quasiparticles and limitations related to the proliferation of thermal fluctuations for sufficiently small grains. For small resistances we find the transition is percolation driven. Whereas at larger resistances the transition occurs above the percolation threshold due to phase fluctuations. JM acknowledes support from an EPSRC Ph.D studentship, AMG acknowledges support from EPSRC, grant No. EP/I004637/1, FCT, grant PTDC/FIS/111348/2009 and a Marie Curie International Reintegration Grant PIRG07-GA-2010-268172.

  15. Reading Text While Driving

    PubMed Central

    Horrey, William J.; Hoffman, Joshua D.

    2015-01-01

    Objective In this study, we investigated how drivers adapt secondary-task initiation and time-sharing behavior when faced with fluctuating driving demands. Background Reading text while driving is particularly detrimental; however, in real-world driving, drivers actively decide when to perform the task. Method In a test track experiment, participants were free to decide when to read messages while driving along a straight road consisting of an area with increased driving demands (demand zone) followed by an area with low demands. A message was made available shortly before the vehicle entered the demand zone. We manipulated the type of driving demands (baseline, narrow lane, pace clock, combined), message format (no message, paragraph, parsed), and the distance from the demand zone when the message was available (near, far). Results In all conditions, drivers started reading messages (drivers’ first glance to the display) before entering or before leaving the demand zone but tended to wait longer when faced with increased driving demands. While reading messages, drivers looked more or less off road, depending on types of driving demands. Conclusions For task initiation, drivers avoid transitions from low to high demands; however, they are not discouraged when driving demands are already elevated. Drivers adjust time-sharing behavior according to driving demands while performing secondary tasks. Nonetheless, such adjustment may be less effective when total demands are high. Application This study helps us to understand a driver’s role as an active controller in the context of distracted driving and provides insights for developing distraction interventions. PMID:25850162

  16. Waveguide sensor for measurement of viscosity of highly viscous fluids

    NASA Astrophysics Data System (ADS)

    Kazys, R.; Sliteris, R.; Raisutis, R.; Zukauskas, E.; Vladisauskas, A.; Mazeika, L.

    2013-11-01

    Ultrasonic waveguide sensor for measurement of viscosity of highly viscous fluids has been developed. The measurement principle is based on application of guided shear-horizontal SH0 mode of the Lamb waves propagating in an aluminium planar waveguide immersed in a viscous liquid. Attenuation of the guided wave depends on viscosity of the surrounding liquid and is used for viscosity estimation. The developed sensor is mechanically robust and may be used for in-line process control of viscous liquids.

  17. Non-invasive fluid density and viscosity measurement

    DOEpatents

    Sinha, Dipen N.

    2012-05-01

    The noninvasively measurement of the density and viscosity of static or flowing fluids in a section of pipe such that the pipe performs as the sensing apparatus, is described. Measurement of a suitable structural vibration resonance frequency of the pipe and the width of this resonance permits the density and viscosity to be determined, respectively. The viscosity may also be measured by monitoring the decay in time of a vibration resonance in the pipe.

  18. Comparison of splashing in high- and low-viscosity liquids.

    PubMed

    Stevens, Cacey S; Latka, Andrzej; Nagel, Sidney R

    2014-06-01

    We explore the evolution of a splash when a liquid drop impacts a smooth dry surface. There are two splashing regimes that occur when the liquid viscosity is varied as is evidenced by its dependence on ambient gas pressure. A high-viscosity drop splashes by emitting a thin sheet of liquid from a spreading liquid lamella long after the drop has first contacted the solid. Likewise, we find that there is also a delay in the ejection of a thin sheet when a low-viscosity drop splashes. We show how the ejection time of the thin sheet depends on liquid viscosity and ambient gas pressure. PMID:25019878

  19. Notes on shear viscosity bound violation in anisotropic models

    NASA Astrophysics Data System (ADS)

    Ge, XianHui

    2016-03-01

    The shear viscosity bound violation in Einstein gravity for anisotropic black branes is discussed, with the aim of constraining the deviation of the shear viscosity-entropy density ratio from the shear viscosity bound using causality and thermodynamics analysis. The results show that no stringent constraints can be imposed. The diffusion bound in anisotropic phases is also studied. Ultimately, it is concluded that shear viscosity violation always occurs in cases where the equation of motion of the metric fluctuations cannot be written in a form identical to that of the minimally coupled massless scalar fields.

  20. DWPF STARTUP FRIT VISCOSITY MEASUREMENT ROUND ROBIN RESULTS

    SciTech Connect

    Crum, Jarrod V.; Edwards, Tommy B.; Russell, Renee L.; Workman, Phyllis J.; Schweiger, Michael J.; Schumacher, Ray F.; Smith, Donald E.; Peeler, David K.; Vienna, John D.

    2012-07-31

    A viscosity standard is needed to replace the National Institute of Standards and Technology (NIST) glasses currently being used to calibrate viscosity measurement equipment. The current NIST glasses are either unavailable or less than ideal for calibrating equipment to measure the viscosity of high-level waste glasses. This report documents the results of a viscosity round robin study conducted on the Defense Waste Processing Facility (DWPF) startup frit. DWPF startup frit was selected because its viscosity-temperature relationship is similar to most DWPF and Hanford high-level waste glass compositions. The glass underwent grinding and blending to homogenize the large (100 lb) batch. Portions of the batch were supplied to the laboratories (named A through H) for viscosity measurements following a specified temperature schedule with a temperature range of 1150 C to 950 C and with an option to measure viscosity at lower temperatures if their equipment was capable of measuring at the higher viscosities. Results were used to fit the Vogel-Tamman-Fulcher and Arrhenius equations to viscosity as a function of temperature for the entire temperature range of 460 C through 1250 C as well as the limited temperature interval of approximately 950 C through 1250 C. The standard errors for confidence and prediction were determined for the fitted models.

  1. Viscosity of Mixtures of α-Tocopherol Acetate + Mesitylene

    NASA Astrophysics Data System (ADS)

    Szwajczaka, Elżbieta; Stagraczyński, Ryszard; Herba, Henryk; Świergielb, Jolanta; Jadżyn, Jan

    2009-08-01

    The paper presents results of the share viscosity measurements performed as a function of temperature and concentration for mixtures of α-tocopherol acetate (vitamine E acetate) and mesitylene, two liquids of essentially different viscosity (four order of magnitude difference at 280 K). The viscosity/ temperature dependence for pure α-tocopherol acetate as well as for the mixtures studied can be well described with the Vogel-Fulcher-Tammann equation. The viscosities of the mixtures exhibit a strong negative deviation from the rule of additive dependence on concentration and for increasing temperature the maximum value of the deviation shows an exponential decreasing.

  2. Development of Viscosity Model for Petroleum Industry Applications

    NASA Astrophysics Data System (ADS)

    Motahhari, Hamed reza

    Heavy oil and bitumen are challenging to produce and process due to their very high viscosity, but their viscosity can be reduced either by heating or dilution with a solvent. Given the key role of viscosity, an accurate viscosity model suitable for use with reservoir and process simulators is essential. While there are several viscosity models for natural gases and conventional oils, a compositional model applicable to heavy petroleum and diluents is lacking. The objective of this thesis is to develop a general compositional viscosity model that is applicable to natural gas mixtures, conventional crudes oils, heavy petroleum fluids, and their mixtures with solvents and other crudes. The recently developed Expanded Fluid (EF) viscosity correlation was selected as a suitable compositional viscosity model for petroleum applications. The correlation relates the viscosity of the fluid to its density over a broad range of pressures and temperatures. The other inputs are pressure and the dilute gas viscosity. Each fluid is characterized for the correlation by a set of fluid-specific parameters which are tuned to fit data. First, the applicability of the EF correlation was extended to asymmetric mixtures and liquid mixtures containing dissolved gas components. A new set of mass-fraction based mixing rules was developed to calculate the fluid-specific parameters for mixtures. The EF correlation with the new set of mixing rules predicted the viscosity of over 100 mixtures of hydrocarbon compounds and carbon dioxide with overall average absolute relative deviations (AARD) of less than 10% either with measured densities or densities estimated by Advanced Peng-Robinson equation of state (APR EoS). To improve the viscosity predictions with APR EoS-estimated densities, general correlations were developed for non-zero viscosity binary interaction parameters. The EF correlation was extended to non-hydrocarbon compounds typically encountered in natural gas industry. It was

  3. Effective kinematic viscosity of turbulent He II

    SciTech Connect

    Chagovets, T. V.; Gordeev, A. V.; Skrbek, L.

    2007-08-15

    The temperature dependence of the effective kinematic viscosity of turbulent He II, {nu}{sub eff}(T), is deduced from second sound attenuation data using the late stage of decay of thermally induced counterflow He II turbulence in two channels of square cross section. It is shown to qualitatively agree with the published data for {nu}{sub eff}(T) calculated based on experiments on decaying-grid-generated He II turbulence [Niemela et al., J. Low Temp. Phys. 138, 537 (2005)]. Corrections to these data due to the 'sine squared' law that describes attenuation of the second sound wave propagating along an arbitrary direction with respect to the direction of the core of a quantized vortex in turbulent He II are discussed and applied.

  4. Viscosity of the lithosphere of Enceladus

    NASA Technical Reports Server (NTRS)

    Passey, Q. R.

    1983-01-01

    Regions of the Enceladus surface are shown by high resolution Voyager II images to be highly cratered, as if by heavy bombardment, with crater forms similar to those of fresh lunar surfaces but often shallower in depth. The flattening of these craters and the bowing up of their floors indicate viscous relaxation of the topography. Viscosity at the top of the lithosphere is suggested by crater form analysis to lie between 10 to the 24th and 10 to the 25th P. The zones where flattened craters occur may be regions of past or present heat flow that is higher than in adjacent terrains. Encedalus probably has a mixture of ammonia ice and water ice in the lithosphere, while the lithospheres of Ganymede and Callisto are primarily composed of water ice

  5. Piezoelectric drive circuit

    DOEpatents

    Treu, C.A. Jr.

    1999-08-31

    A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes. 7 figs.

  6. Piezoelectric drive circuit

    DOEpatents

    Treu, Jr., Charles A.

    1999-08-31

    A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes.

  7. Dual drive actuators

    NASA Technical Reports Server (NTRS)

    Packard, D. T.

    1982-01-01

    A new class of electromechanical actuators is described. These dual drive actuators were developed for the NASA-JPL Galileo Spacecraft. The dual drive actuators are fully redundant and therefore have high inherent reliability. They can be used for a variety of tasks, and they can be fabricated quickly and economically.

  8. Implications of the lopsided growth for the viscosity of the Earth's inner core

    NASA Astrophysics Data System (ADS)

    Mizzon, H.; Monnereau, M.

    2011-12-01

    Two main seismic features characterize Earth's inner core: a North-South polar anisotropy and an East-West dichotomy of P-wave propagation properties (velocity and attenuation). Anisotropy is expected if shear deformation is induced by convective motions. However, translation has recently been put forward as the dominant mode of convection of the inner core (1, 2). Combined with a simple diffusive grain growth model, this mechanism is able to explain the observed seismic dichotomy, but not the bulk anisotropy. The source of anisotropy has therefore to be sought in the shear motions caused by higher modes of convection. Using a hybrid finite-difference spherical harmonics Navier-Stokes solver, this study investigates the interplay between translation and convection in a 3D spherical model. Three parameters act independently: viscosity, internal heating and outer core convection speed at the surface of the inner core. Particular attention has been paid to the implementation of realistic thermodynamic exchanges and permeable conditions at the inner core boundary. Our numerical simulations show the dominance of pure translation for viscosities higher than 1020 Pas. Translation is almost completely hampered by convective motions for viscosities lower than 1018 Pas. Between these bounds, translation and convection develop, but convective downwellings are restricted to the coldest hemisphere where crystallization occurs. On the opposite side, shear is almost absent, thereby allowing grain growth. We propose that the coexistence of translation and convection observed in our numerical models may explain simultaneously the presence of bulk anisotropy and the seismic dichotomy. (1) Monnereau et al., Science 2010. (2) Alboussiere et al., Nature 2010.

  9. Sensor for viscosity and shear strength measurement

    SciTech Connect

    Ebadian, M.A.; Dillion, J.; Moore, J.; Jones, K.

    1998-01-01

    Measurement of the physical properties (viscosity and density) of waste slurries is critical in evaluating transport parameters to ensure turbulent flow through transport pipes. The environment for measurement and sensor exposure is extremely harsh; therefore, reliability and ruggedness are critical in the sensor design. Two different viscometer techniques are being investigated in this study, based on: magnetostrictive pulse generated acoustic waves; and an oscillating cylinder. Prototype sensors have been built and tested which are based on both techniques. A base capability instrumentation system has been designed, constructed, and tested which incorporates both of these sensors. It requires manual data acquisition and off-line calculation. A broad range of viscous media has been tested using this system. Extensive test results appear in this report. The concept for each technique has been validated by these test results. This base capability system will need to be refined further before it is appropriate for field tests. The mass of the oscillating system structure will need to be reduced. A robust acoustic probe assembly will need to be developed. In addition, in March 1997 it was made known for the first time that the requirement was for a deliverable automated viscosity instrumentation system. Since then such a system has been designed, and the hardware has been constructed so that the automated concept can be proved. The rest of the hardware, which interfaced to a computer, has also been constructed and tested as far as possible. However, for both techniques the computer software for automated data acquisition, calculation, and logging had not been completed before funding and time ran out.

  10. Hydrodynamics of spacetime and vacuum viscosity

    NASA Astrophysics Data System (ADS)

    Eling, Christopher

    2008-11-01

    It has recently been shown that the Einstein equation can be derived by demanding a non-equilibrium entropy balance law dS = δQ/T+diS hold for all local acceleration horizons through each point in spacetime. The entropy change dS is proportional to the change in horizon area while δQ and T are the energy flux across the horizon and Unruh temperature seen by an accelerating observer just inside the horizon. The internal entropy production term diS is proportional to the squared shear of the horizon and the ratio of the proportionality constant to the area entropy density is hbar/4π. Here we will show that this derivation can be reformulated in the language of hydrodynamics. We postulate that the vacuum thermal state in the Rindler wedge of spacetime obeys the holographic principle. Hydrodynamic perturbations of this state exist and are manifested in the dynamics of a stretched horizon fluid at the horizon boundary. Using the equations of hydrodynamics we derive the entropy balance law and show the Einstein equation is a consequence of vacuum hydrodynamics. This result implies that hbar/4π is the shear viscosity to entropy density ratio of the local vacuum thermal state. The value hbar/4π has attracted much attention as the shear viscosity to entropy density ratio for all gauge theories with an Einstein gravity dual. It has also been conjectured as the universal lower bound on the ratio. We argue that our picture of the vacuum thermal state is consistent with the physics of the gauge/gravity dualities and then consider possible applications to open questions.

  11. Design of traction drives

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Zaretsky, E. V.

    1985-01-01

    Traction drives are among the simplest of all speed-changing mechanisms. Because of their simplicity and their ability to smoothly and continuously adjust speed, they are excellent choices for many drive system applications. They have been used in industrial service for more than 100 years. Today's traction drives have power capacities which rival the best gear and belt drives due to modern traction fluids and highly fatigue-resistant bearing steels. This report summarizes methods to analyze and size traction drives. Lubrication principles, contact kinematics, stress, fatigue life, and performance prediction methods are presented. The effects of the lubricant's traction characteristics on life and power loss are discussed. An example problem is given which illustrates the effects of spin on power loss. Loading mechanism design and the design of nonlubricated friction wheels and rings are also treated.

  12. Quantification of Viscosity and Capillary Pressure Anomalies for Polar Liquids in 2D Hydrophilic Nano-Confinements

    NASA Astrophysics Data System (ADS)

    Kelly, S. A.; Torres-Verdin, C.; Balhoff, M.

    2014-12-01

    Interest in liquid and interfacial behavior within nano-confinements spans many disciplines. Geophysical interest originates from a desire to understand flow mechanisms through hydrocarbon-rich nano-porous shale media, especially communication between fractures and the adjacent nano-porous matrix (imbibition). This work investigates the extent of boundary layer nucleation during polar liquid flows in hydrophilic nano-confinements via discrepancies seen in viscosity and capillary pressure from their bulk values. We perform our experiments in two-dimensional nanochannels of varying size and as small as 30 nm x 60 nm in cross section and still obtain visual data with reflected differential interference contrast (DIC) microscopy. The simple geometry of the nanochannels enables the comparison against analytical transport solutions. By designing a nanochannel experiment that allows us to monitor the rate of fluid imbibition and volume loss of a trapped air pocket the liquid is imbibing into, we are able to decouple capillary pressure and viscosity from imbibition data, as well as gain information about gas partitioning at the meniscus interface. Our current experiments are performed with organic solvents within siliceous nanochannels and the results of the decoupling scheme indicate that for rectangular nanochannels with heights of 60 nm and varying widths, effective viscosity is consistently between 4-12 times higher than the bulk value and capillary pressure is around 50% less than the macroscopic Young-Laplace equation prediction. These results equate to the nucleation of wall boundary layers on the order of tens of molecular layers thick. Structured boundary layers have an inherently increased viscosity compared to the liquid bulk value, resulting in a significant reduction in imbibition efficacy. This presence of approximately 15 nm boundary layers in on the threshold of two different theories - thin bimolecular boundary layers and exclusion zones (thick boundary

  13. Viscosity of α-pinene secondary organic material and implications for particle growth and reactivity

    SciTech Connect

    Renbaum-Wolff, Lindsay; Grayson, James W.; Bateman, Adam P.; Kuwata, Mikinori; Sellier, Mathieu; Murray, Benjamin J.; Shilling, John E.; Martin, Scot T.; Bertram, Allan K.

    2013-05-14

    Particles composed of secondary organic material (SOM) are abundant in the lower troposphere and play important roles in climate, air quality, and health. The viscosity of these particles is a fundamental property that is presently poorly quantified for conditions relevant to the lower troposphere. Using two new techniques, namely a bead-mobility technique and a poke-flow technique, in conjunction with simulations of fluid flow, we measure the viscosity of the watersoluble component of SOM produced by α-pinene ozonolysis. The viscosity is comparable to that of honey at 90% relative humidity (RH), comparable to that of peanut butter at 70% RH and greater than or comparable to that of bitumen for ≤ 30% RH, implying that the studied SOM ranges from liquid to semisolid/solid at ambient relative humidities. With the Stokes-Einstein relation, the measured viscosities further imply that the growth and evaporation of SOM by the exchange of organic molecules between the gas and condensed phases may be confined to the surface region when RH ≤ 30%, suggesting the importance of an adsorption-type mechanism for partitioning in this regime. By comparison, for RH ≥ 70% partitioning of organic molecules may effectively occur by an absorption mechanism throughout the bulk of the particle. Finally, the net uptake rates of semi-reactive atmospheric oxidants such as O3 are expected to decrease by two to five orders of magnitude for a change in RH from 90% to ≤ 30% RH, with possible implications for the rates of chemical aging of SOM particles in the atmosphere.

  14. Guiding-center hall viscosity and intrinsic dipole moment of fractional quantum Hall states

    NASA Astrophysics Data System (ADS)

    Park, YeJe

    The fractional quantum Hall effect (FQHE) is the archetype of the strongly correlated systems and the topologically ordered phases. Unlike the integer quantum Hall effect (IQHE) which can be explained by single-particle physics, FQHE exhibits many emergent properties that are due to the strong correlation among many electrons. In this Thesis, among those emergent properties of FQHE, we focus on the guiding-center metric, the guiding-center Hall viscosity, the guiding-center spin, the intrinsic electric dipole moment and the orbital entanglement spectrum. Specifically, we show that the discontinuity of guiding-center Hall viscosity (a bulk property) at edges of incompressible quantum Hall fluids is associated with the presence of an intrinsic electric dipole moment on the edge. If there is a gradient of drift velocity due to a non-uniform electric field, the discontinuity in the induced stress is exactly balanced by the electric force on the dipole. We show that the total Hall viscosity has two distinct contributions: a "trivial'' contribution associated with the geometry of the Landau orbits, and a non-trivial contribution associated with guiding-center correlations. We describe a relation between the intrinsic dipole moment and "momentum polarization'', which relates the guiding-center Hall viscosity to the "orbital entanglement spectrum(OES)''. We observe that using the computationally-more-onerous "real-space entanglement spectrum (RES)'' in the momentum polarization calculation just adds the trivial Landau-orbit contribution to the guiding-center part. This shows that all the non-trivial information is completely contained in the OES, which also exposes a fundamental topological quantity gamma = c˜ - nu, the difference between the "chiral stress-energy anomaly'' (or signed conformal anomaly) and the chiral charge anomaly. This quantity characterizes correlated fractional quantum Hall fluids, and vanishes in integer quantum Hall fluids which are uncorrelated.

  15. Viscosity controls humidity dependence of N2O5 uptake to citric acid aerosol

    NASA Astrophysics Data System (ADS)

    Gržinić, G.; Bartels-Rausch, T.; Berkemeier, T.; Türler, A.; Ammann, M.

    2015-12-01

    The heterogeneous loss of dinitrogen pentoxide (N2O5) to aerosol particles has a significant impact on the night-time nitrogen oxide cycle and therefore the oxidative capacity in the troposphere. Using a 13N short-lived radioactive tracer method, we studied the uptake kinetics of N2O5 on citric acid aerosol particles as a function of relative humidity (RH). The results show that citric acid exhibits lower reactivity than similar dicarboxylic and polycarboxylic acids, with uptake coefficients between ∼ 3 × 10-4-∼ 3 × 10-3 depending on humidity (17-70 % RH). At RH above 50 %, the magnitude and the humidity dependence can be best explained by the viscosity of citric acid as compared to aqueous solutions of simpler organic and inorganic solutes and the variation of viscosity with RH and, hence, diffusivity in the organic matrix. Since the diffusion rates of N2O5 in highly concentrated citric acid solutions are not well established, we present four different parameterizations of N2O5 diffusivity based on the available literature data or estimates for viscosity and diffusivity of H2O. Above 50 % RH, uptake is consistent with the reacto-diffusive kinetic regime whereas below 50 % RH, the uptake coefficient is higher than expected from hydrolysis of N2O5 within the bulk of the particles, and the uptake kinetics is most likely limited by loss on the surface only. This study demonstrates the impact of viscosity in highly oxidized and highly functionalized secondary organic aerosol material on the heterogeneous chemistry of N2O5 and may explain some of the unexpectedly low loss rates to aerosol derived from field studies.

  16. Dynamic measurement of bulk modulus

    NASA Technical Reports Server (NTRS)

    Dowler, W. L.; Strand, L. D.

    1979-01-01

    Technique based on measuring phase difference between microwave reference and test signals and has been used to determine change in bulk modulus of solid-fuel rocket propellants should be useful in studying other dielectric materials.

  17. Bulk pesticide storage - state perspective

    SciTech Connect

    Buzicky, G.

    1994-12-31

    State bulk pesticide storage regulations continue to evolve differentially due, in large part, to the absence of federal regulations. This is about to change because of the pending promulgation of 40 CFR Part 165, as amended in 1988 by the Environmental Protection Agency (EPA) rules regarding storage, handling and disposal. Until final adoption of the rules by EPA, states continue to address bulk pesticide storage and handling according to individual state statute, rules and guidelines.

  18. Evaluation of the synergistic effects of milk proteins in a rapid viscosity analyzer.

    PubMed

    Stephani, Rodrigo; Borges de Souza, Alisson; Leal de Oliveira, Marcone Augusto; Perrone, Ítalo Tuler; Fernandes de Carvalho, Antônio; Cappa de Oliveira, Luiz Fernando

    2015-12-01

    Protein systems (PS) are routinely used by companies from Brazil and around the globe to improve the texture, yield, and palatability of processed foods. Understanding the synergistic behavior among the different protein structures of these systems during thermal treatment under the influence of pH can help to better define optimum conditions for products and processes. The interpretation of the reactions and interactions that occur simultaneously among the protein constituents of these systems as dispersions during thermal processing is still a major challenge. Here, using a rapid viscosity analyzer, we observed the rheological changes in the startup viscosities of 5 PS obtained by combining varying proportions of milk protein concentrate and whey protein concentrate under different conditions of pH (5.0, 6.5, and 7.0) and heat processing (85°C/15min and 95°C/5min). The solutions were standardized to 25% of total solids and 17% of protein. Ten analytical parameters were used to characterize each of the startup-viscosity ramps for 35 experiments conducted in a 2×3 × 5 mixed planning matrix, using principal component analysis to interpret behavioral similarities. The study showed the clear influence of pH 5.5 in the elevation of the initial temperature of the PS startup viscosity by at least 5°C, as well as the effect of different milk protein concentrate:whey protein concentrate ratios above 15:85 at pH 7.0 on the viscographic profile curves. These results suggested that the primary agent driving the changes was the synergism among the reactions and interactions of casein with whey proteins during processing. This study reinforces the importance of the rapid viscosity analyzer as an analytical tool for the simulation of industrial processes involving PS, and the use of the startup viscosity ramp as a means of interpreting the interactions of system components with respect to changes related to the treatment temperature. PMID:26409966

  19. Beyond baking soda: Demonstrating the link between volcanic eruptions and viscosity to all ages

    NASA Astrophysics Data System (ADS)

    Smithka, I. N.; Walters, R. L.; Harpp, K. S.

    2014-12-01

    Public interest in volcanic eruptions and societal relevance of volcanic hazards provide an excellent basis for successful earth science outreach. During a museum-based earth science outreach event free and open to the public, we used two new interactive experiments to illustrate the relationship between gas content, magma viscosity, and eruption style. Learning objectives for visitors are to understand: how gas drives volcanic eruptions, the differences between effusive and explosive eruption styles, viscosity's control on gas pressure within a magma reservoir, and the role of gas pressure on eruption style. Visitors apply the scientific method by asking research questions and testing hypotheses by conducting the experiments. The demonstrations are framed with real life examples of volcanic eruptions (e.g., Mt. St. Helens eruption in 1980), providing context for the scientific concepts. The first activity demonstrates the concept of fluid viscosity and how gas interacts with fluids of different viscosities. Visitors blow bubbles into water and corn syrup. The corn syrup is so viscous that bubbles are trapped, showing how a more viscous material builds up higher gas pressure. Visitors are asked which kind of magma (high or low viscosity) will produce an explosive eruption. To demonstrate an explosive eruption, visitors add an Alka-Seltzer tablet to water in a snap-top film canister. The reaction rapidly produces carbon dioxide gas, increasing pressure in the canister until the lid pops off and the canister launches a few meters into the air (tinyurl.com/nzsgfoe). Increasing gas pressure in the canister is analogous to gas pressure building within a magma reservoir beneath a volcano. The lid represents high-viscosity magma that prevents degassing, causing gas pressure to reach explosive levels. This interactive activity is combined with a display of an effusive eruption: add vinegar to baking soda in a model volcano to produce a quick-flowing eruption. These

  20. Rheology and tribology of lubricants with polymeric viscosity modifiers

    NASA Astrophysics Data System (ADS)

    Babak, LotfizadehDehkordi

    Elastohydrodynamic lubrication (EHL) theory has been used to model the lubrication state of antifriction machine elements, where initial viscosity and pressure viscosity coefficients are essential parameters in film thickness modeling. Since the pressures of lubricants in the contact zone can be very high, it is important to know the rheological properties of lubricants in these pressure and temperature regimes. The characteristics of viscosity behavior as a function of pressure are also essential for a universal definition of the pressure viscosity coefficient in order to estimate film thickness in an EHL regime. In this study, viscosities and pressure-viscosity coefficients of ten commercial engine and gear oils and seventeen laboratory-produced oil/polymer viscosity modifiers (VM) additives are measured up to 1.3 GPa at 40, 75 and 100 °C. For the first time, a sharp increase in the viscosity and piezoviscous factor is observed in both mineral-based and synthetic-based oils with different VMs. Analysis of the experimental results indicates that sharp increase in viscosity observed in these experiments are believed to arise from physical changes in the VMs, that is liquid-solid phase transition. Evidence is offered that polymer properties such as molecular weight, concentration and structure influence the onset of the phase transitions. A modified Yasutomi model, which normally describes the pressure dependence of the viscosity of lubricants very well, fails to predict the viscosity of the specimens above the onset of sharp increase in viscosity. A design of experiment (DOE) analysis using Design-Expert software indicates that pressure and temperature are the most critical parameters in the viscosity variation. Tribological tests demonstrate that wear in the contact, zone occurs at temperatures and stresses that coincides with the VM phase transitions in both commercial and laboratory synthesized oil/VMs. Tribological results also indicate that the onset of the

  1. Depletion controlled surface deposition of uncharged colloidal spheres from stable bulk dispersions.

    PubMed

    Ouhajji, Samia; Nylander, Tommy; Piculell, Lennart; Tuinier, Remco; Linse, Per; Philipse, Albert P

    2016-05-01

    The competition between surface adsorption and bulk aggregation was investigated for silica colloids dispersed in cyclohexane in contact with hydrophobized silica substrates. Central to this study is that the colloids and surfaces have the same material and surface properties. Colloid-colloid and colloid-surface interactions were controlled by addition of polymers providing depletion interaction. Bulk instability was determined by turbidity and viscosity measurements and surface adsorption by ellipsometry measurements. At increasing polymer concentration, strong surface adsorption occurred at polymer concentrations below that required for bulk phase separation. Complementary Monte Carlo simulations with the use of a new weak depletion theory support quantitatively the experimental observation of the existence of an interval of interaction strength at which aggregation in bulk is negligible while surface adsorption is substantial. PMID:27025949

  2. Dynamics of Anisotropic Bianchi Type-III Bulk Viscous String Model with Magnetic Field

    NASA Astrophysics Data System (ADS)

    Singh, M. K.; Ram, Shri

    2014-07-01

    In this paper, we discuss the dynamics of spatially homogeneous and anisotropic Bianchi type-III string cosmological model in presence of bulk viscous fluid and electromagnetic field. Exact solutions of Einstein's field equations are obtained by assuming (i) a special form of the deceleration parameter and (ii) the component of the shear scalar tensor is proportional to mean Hubble parameter. The source of magnetic field is due to an electric current produced along z-axis. The role of bulk viscosity and magnetic field in establishing string phase of universe is presented. The physical and kinematical features of solutions are also discussed in detail.

  3. Vision and Driving

    PubMed Central

    Owsley, Cynthia; McGwin, Gerald

    2010-01-01

    Driving is the primary means of personal travel in many countries and is relies heavily on vision for its successful execution. Research over the past few decades has addressed the role of vision in driver safety (motor vehicle collision involvement) and in driver performance (both on-road and using interactive simulators in the laboratory). Here we critically review what is currently known about the role of various aspects of visual function in driving. We also discuss translational research issues on vision screening for licensure and re-licensure and rehabilitation of visually impaired persons who want to drive. PMID:20580907

  4. Redundant motor drive system

    NASA Technical Reports Server (NTRS)

    Calvert, J. A. (Inventor)

    1980-01-01

    A drive system characterized by a base supporting a pair of pillars arranged in spaced parallelism, a shaft extended between and supported by the pillars for rotation about the longitudinal axis thereof, a worm gear affixed to the shaft and supported in coaxial relation therewith is described. A bearing housing of a sleeve like configuration is concentrically related to the shaft and is supported thereby for free rotation. A first and a second quiescent drive train, alternatively activatable, is provided for imparting rotation into said bearing housing. Each of the drive trains is characterized by a selectively energizable motor connected to a spur gear.

  5. The Test Drive

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken at NASA's Jet Propulsion Laboratory shows engineers rehearsing the sol 133 (June 8, 2004) drive into 'Endurance' crater by NASA's Mars Exploration Rover Opportunity. Engineers and scientists have recreated the martian surface and slope the rover will encounter using a combination of bare and thinly sand-coated rocks, simulated martian 'blueberries' and a platform tilted at a 25-degree angle. The results of this test convinced engineers that the rover was capable of driving up and down a straight slope before it attempted the actual drive on Mars.

  6. Improved acoustic viscosimeter technique. [for determining fluid shear viscosity

    NASA Technical Reports Server (NTRS)

    Fisch, M. R.; Moeller, R. P.; Carome, E. F.

    1976-01-01

    An improved technique has been developed for studies of the shear viscosity of fluids. It utilizes an acoustic resonator as a four-terminal electrical device; the resonator's amplitude response may be determined directly and simply related to the fluid's viscosity. The use of this technique is discussed briefly and data obtained in several fluids is presented.

  7. Viscosity of concentrated suspensions of sphere/rod mixtures

    SciTech Connect

    Mor, R.; Gottlieb, M.; Graham, A.L.; Mondy, L.A.

    1996-05-01

    This paper discusses the viscosity of concentrated suspensions of sphere/rod mixtures by adopting the Thomas relations for spheres and Milliken`s for randomly oriented rods with aspect ratio of 20. The relative viscosity of a mixed suspension may now be calculated for any combination of rods (of aspect ratio 20) and spheres.

  8. On the shear viscosity of 3D Yukawa liquids

    SciTech Connect

    Donko, Z.; Hartmann, P.

    2008-09-07

    We report calculations of the shear viscosity of three-dimensional strongly-coupled Yukawa liquids, based on two different non-equilibrium molecular dynamics methods. The present simulations intend to improve the accuracy of shear viscosity data, compared to those obtained in earlier studies.

  9. Note: Precision viscosity measurement using suspended microchannel resonators

    SciTech Connect

    Lee, I.; Lee, J.; Park, K.

    2012-11-15

    We report the characterization of a suspended microchannel resonator (SMR) for viscosity measurements in a low viscosity regime (<10 mPa s) using two measurement schemes. First, the quality factor (Q-factor) of the SMR was characterized with glycerol-water mixtures. The measured Q-factor at 20 Degree-Sign C exhibits a bilinear behavior with the sensitivity of 1281 (mPa s){sup -1} for a lower (1-4 mPa s) and 355 (mPa s){sup -1} for a higher viscosity range (4-8 mPa s), respectively. The second scheme is the vibration amplitude monitoring of the SMR running in a closed loop feedback. When compared in terms of the measurement time, the amplitude-based measurement takes only 0.1 {approx} 1 ms while the Q-factor-based measurement takes {approx}30 s. However, the viscosity resolution of the Q-factor-based measurement is at least three times better than the amplitude-based measurement. By comparing the Q-factors of heavy water and 9.65 wt.% glycerol-water mixture that have very similar viscosities but different densities, we confirmed that the SMR can measure the dynamic viscosity without the density correction. The obtained results demonstrate that the SMR can measure the fluid viscosity with high precision and even real-time monitoring of the viscosity change is possible with the amplitude-based measurement scheme.

  10. Numerical viscosity and the entropy condition for conservative difference schemes

    NASA Technical Reports Server (NTRS)

    Tadmor, E.

    1983-01-01

    Consider a scalar, nonlinear conservative difference scheme satisfying the entropy condition. It is shown that difference schemes containing more numerical viscosity will necessarily converge to the unique, physically relevant weak solution of the approximated conservation equation. In particular, entropy satisfying convergence follows for E schemes - those containing more numerical viscosity than Godunov's scheme.

  11. Homeostasis of plasma membrane viscosity in fluctuating temperatures.

    PubMed

    Martinière, Alexandre; Shvedunova, Maria; Thomson, Adrian J W; Evans, Nicola H; Penfield, Steven; Runions, John; McWatters, Harriet G

    2011-10-01

    Temperature has a direct effect at the cellular level on an organism. For instance, in the case of biomembranes, cooling causes lipids to lose entropy and pack closely together. Reducing temperature should, in the absence of other factors, increase the viscosity of a lipid membrane. We have investigated the effect of temperature variation on plasma membrane (PM) viscosity. We used dispersion tracking of photoactivated green fluorescent protein (GFP) and fluorescence recovery after photobleaching in wild-type and desaturase mutant Arabidopsis thaliana plants along with membrane lipid saturation analysis to monitor the effect of temperature and membrane lipid composition on PM viscosity. Plasma membrane viscosity in A. thaliana is negatively correlated with ambient temperature only under constant-temperature conditions. In the more natural environment of temperature cycles, plants actively manage PM viscosity to counteract the direct effects of temperature. Plasma membrane viscosity is regulated by altering the proportion of desaturated fatty acids. In cold conditions, cell membranes accumulate desaturated fatty acids, which decreases membrane viscosity and vice versa. Moreover, we show that control of fatty acid desaturase 2 (FAD2)-dependent lipid desaturation is essential for this homeostasis of membrane viscosity. Finally, a lack of FAD2 function results in aberrant temperature responses. PMID:21762166

  12. Surface tension and viscosity of nuclei in liquid drop model

    NASA Astrophysics Data System (ADS)

    Khokonov, A. Kh

    2015-11-01

    An analytical solution for the capillary oscillations of the charged drop in dielectric medium obtained with taking into account the damping due to viscosity. The model has been applied for the estimation of even-even spherical nuclei surface tension and nuclei viscosity. Attenuation factor to nuclear capillary oscillation frequency ratio has been found.

  13. Viscosity Reduction in Liquid Suspensions by Electric or Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Tao, R.; Xu, X.

    Reducing the viscosity of liquid suspensions is of great importance in science and engineering. We present a theory and experiments that a suitable electric or magnetic field pulse can effectively reduce the viscosity for several hours with no appreciable change of temperature. Positive experimental results with magnetorheological fluids and crude oil suggest a broad range of practical applications.

  14. Nucleoplasmic viscosity of living cells investigated by fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Liang, Lifang; Xing, Da; Chen, Tongshen; Pei, Yihui

    2007-11-01

    Fluorescence correlation spectroscopy (FCS) is a new kind of real-time, high-speed and single-molecule technique. It is used to detect the kinetic characteristics of fluorescent dye such as diffusion coefficient in the aqueous solution. Combined with confocal microscope optics, it has been now widely applied in cell biological research. Through a time correlation analysis of spontaneous intensity fluctuations, this technique with EGFP as a probe is capable of determining viscosity of fluids according to Stokes-Einstein equation. Nucleoplasmic viscosity is an important physical parameter to quantify the rheological characteristics of the nucleoplasm. Investigation on nucleoplasmic viscosity plays an important role in further understanding intranuclear environment. In this paper, FCS is introduced to noninvasively investigate nucleoplasmic viscosity of living cells. The results show that nucleoplasmic viscosity of lung adenocarcinoma (ASTC-a-1) cells is 2.55+/-0.61 cP and nucleoplasmic viscosity is larger than cytoplasmic viscosity at 37 °C (pH 7.4). In addition, significant changes in nucleoplasmic viscosity are detected by FCS when cells are exposed to hyper or hypotonic medium. Our study suggests that FCS can be used to detect the kinetic characteristics of biomolecules in living cells and thus helps to investigate the dynamic changes of the microenvironment in the cell.

  15. Viscosity measurements and empirical predictions for coal slags

    SciTech Connect

    Matyas, Josef; Sundaram, S K; Rodriguez, Carmen P; Heredia-Langner, Alejandro; Arrigoni, Benjamin M

    2009-10-25

    Slag viscosity in slagging coal gasifier is an important factor affecting the gasification regime and operating cost. Most of the empirical viscosity models of coal slags that are available in the literature are applicable to only limited ranges of temperature and composition. To develop a reliable slag viscosity model, additional data are needed. Slag viscosity was measured under air or reducing atmosphere (calculated pO2~1.2 10-12 atm at 1400°C) at temperatures in the range of 1150-1550°C on 63 statistically designed slags, including 5 actual coal slag compositions and 4 validation slag compositions. The Arrhenius equation, with Arrhenius coefficients A = constant and B expressed as linear function of mass fractions of nine major components was used to fit the viscosity/temperature data. This Arrhenius relationship represents the viscosity–temperature relationship of tested slags reasonably well, = 0.981 (reducing atmosphere) and = 0.974 (air atmosphere). The validation of the model with four randomly selected slags (two from the SciGlass database and two from experimental design) indicated an accurately measured viscosity-temperature data and a fairly good predictive performance of slag viscosity models over designed compositions. The capability of the developed model to predict the viscosity of coal slags under reducing atmosphere was found to be a superior to a number of the most commonly used empirical models in the literature that are based on simplified oxide melts and British or Australian coal ash slags.

  16. Viscosity of bubble- and crystal- bearing magmas: Analogue results

    NASA Astrophysics Data System (ADS)

    Namiki, A.; Manga, M.

    2006-12-01

    Natural magmas often include both phenocrysts and bubbles. Such magmas can be regarded as suspensions including particles and bubbles and should have a viscosity different from the particle- and bubble- free melt. Viscosity is one of the key physical properties that affects eruption dynamics and magma flow. To understand the relation between the viscosity and the volume fraction of bubbles and particles, we directly measure the viscosity of suspensions with both particles and bubbles. Measurements are performed with the 4 degree cone-and-plate type rheometer (Thermo HAAKE Rheoscope 1), which allows us to observe the samples in situ during the measurement. The suspending fluid is corn syrup whose viscosity is 1.7 Pa·s at 23 °C. Particles are Techpolymer (polymethylmethacrylate) 40 μm diameter spheres. Bubbles are made by dissolving baking soda and citric acid; reaction between them generates carbon dioxide. No surfactant is added. The Peclet number is sufficiently large that Brownian motion does not influence our results. The measured viscosity for the suspensions with particles, and with both particles and bubbles, show strong shear thinning. The measured viscosities during increasing and decreasing shear rate differ from each other, indicating that the microstructure is modified by flow. When the deformation of bubbles is not significant, the measured viscosity with bubbles is higher than that without bubbles, and vice versa.

  17. Critical exponent for the viscosity of four binary liquids

    NASA Technical Reports Server (NTRS)

    Berg, Robert F.; Moldover, Michael R.

    1988-01-01

    The viscosity of the following binary mixtures was measured near their consolute points: (1) methanol + cyclohexane, (2) isobutyric acid + water, (3) nitroethane + 3-methylpentane, and (4) 2-butoxyethanol + water. It is shown that the multiplicative hypothesis is valid for these mixtures. It is also found that the concentration closest to critical has the largest viscosity enhancement.

  18. Driving forces: Slab subduction and mantle convection

    NASA Technical Reports Server (NTRS)

    Hager, Bradford H.

    1988-01-01

    Mantle convection is the mechanism ultimately responsible for most geological activity at Earth's surface. To zeroth order, the lithosphere is the cold outer thermal boundary layer of the convecting mantle. Subduction of cold dense lithosphere provides tha major source of negative buoyancy driving mantle convection and, hence, surface tectonics. There are, however, importnat differences between plate tectonics and the more familiar convecting systems observed in the laboratory. Most important, the temperature dependence of the effective viscosity of mantle rocks makes the thermal boundary layer mechanically strong, leading to nearly rigid plates. This strength stabilizes the cold boundary layer against small amplitude perturbations and allows it to store substantial gravitational potential energy. Paradoxically, through going faults at subduction zones make the lithosphere there locally weak, allowing rapid convergence, unlike what is observed in laboratory experiments using fluids with temperature dependent viscosities. This bimodal strength distribution of the lithosphere distinguishes plate tectonics from simple convection experiments. In addition, Earth has a buoyant, relatively weak layer (the crust) occupying the upper part of the thermal boundary layer. Phase changes lead to extra sources of heat and bouyancy. These phenomena lead to observed richness of behavior of the plate tectonic style of mantle convection.

  19. Green stabilization of microscale iron particles using guar gum: bulk rheology, sedimentation rate and enzymatic degradation.

    PubMed

    Gastone, Francesca; Tosco, Tiziana; Sethi, Rajandrea

    2014-05-01

    Guar gum can be used to effectively improve stability and mobility of microscale zerovalent iron particles (MZVI) used in groundwater remediation. Guar gum is a food-grade, environment friendly natural polysaccharide, which is often used as thickening agent in a broad range of food, pharmaceutical and industrial applications. Guar gum solutions are non-Newtonian, shear thinning fluids, characterized by high viscosity in static conditions and low viscosity in dynamic conditions. In particular, the high zero shear viscosity guarantees the MZVI dispersion stability, reducing the sedimentation rate of the particles thus enabling its storage and field operations. In this work, a comprehensive rheological characterization of guar gum-based slurries of MZVI particles is provided. First, we derived a model to link the bulk shear viscosity to the concentration of guar gum and then we applied it for the derivation of a modified Stokes law for the prediction of the sedimentation rate of the iron particles. The influence of the preparation procedure (cold or hot dissolution and high shear processing) on the viscosity and on the stability of the suspensions was then assessed. Finally, the dosage and concentration of enzymes - an environment friendly breaker--were studied for enhancing and controlling the degradation kinetics of the suspensions. The derived empirical relationships can be used for the implementation of an iron slurry flow and transport model and for the design of full scale injection interventions. PMID:24594029

  20. Modelling of bulk superconductor magnetization

    NASA Astrophysics Data System (ADS)

    Ainslie, M. D.; Fujishiro, H.

    2015-05-01

    This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.

  1. Viscosity and compressibility of diacylglycerol under high pressure

    NASA Astrophysics Data System (ADS)

    Malanowski, Aleksander; Rostocki, A. J.; Kiełczyński, P.; Szalewski, M.; Balcerzak, A.; Kościesza, R.; Tarakowski, R.; Ptasznik, S.; Siegoczyński, R. M.

    2013-03-01

    The influence of high pressure on viscosity and compressibility of diacylglycerol (DAG) oil has been presented in this paper. The investigated DAG oil was composed of 82% of DAGs and 18% TAGs (triacylglycerols). The dynamic viscosity of DAG was investigated as a function of the pressure up to 400 MPa. The viscosity was measured by means of the surface acoustic wave method, where the acoustic waveguides were used as sensing elements. As the pressure was rising, the larger ultrasonic wave attenuation was observed, whereas amplitude decreased with the liquid viscosity augmentation. Measured changes of physical properties were most significant in the pressure range near the phase transition. Deeper understanding of DAG viscosity and compressibility changes versus pressure could shed more light on thermodynamic properties of edible oils.

  2. Measurement and correlation of jet fuel viscosities at low temperatures

    NASA Technical Reports Server (NTRS)

    Schruben, D. L.

    1985-01-01

    Apparatus and procedures were developed to measure jet fuel viscosity for eight current and future jet fuels at temperatures from ambient to near -60 C by shear viscometry. Viscosity data showed good reproducibility even at temperatures a few degrees below the measured freezing point. The viscosity-temperature relationship could be correlated by two linear segments when plotted as a standard log-log type representation (ASTM D 341). At high temperatures, the viscosity-temperature slope is low. At low temperatures, where wax precipitation is significant, the slope is higher. The breakpoint between temperature regions is the filter flow temperature, a fuel characteristic approximated by the freezing point. A generalization of the representation for the eight experimental fuels provided a predictive correlation for low-temperature viscosity, considered sufficiently accurate for many design or performance calculations.

  3. The minimum mantle viscosity of an accreting earth

    NASA Technical Reports Server (NTRS)

    Cooperman, S. A.

    1983-01-01

    The minimum mantle viscosity in an earth accreting from planetesimals is estimated. A plausible distribution of planetesimal sizes deposits enough energy to melt the outer nine-tenths of earth's mass; however, vigorous convection keeps temperatures near the solidus. Viscosity is significantly lower than prevails now. The temperature-dependent viscosity provides self-regulation so there is a continuing balance between accretional energy input and heat transfer out. This allows calculation of the minimum viscosity necessary to transfer out heat by a Nu/Ra-number relation. Typical viscosities are 0.1 to a million sq m/sec, lowest at mid-accretion when the mass growth rate is largest. Terrestrial planets are compared, and minimum iron descent times to central lithospheres are calculated.

  4. Shear viscosity relaxation of a critical binary liquid.

    PubMed

    Behrends, Ralph; Kaatze, Udo

    2003-07-01

    Two series of diffusion coefficients D are reported for the triethylamine-water binary critical mixture. One has been obtained from quasielastic light scattering measurements, the other one has been derived from broadband ultrasonic spectra, yielding the relaxation rate of order parameter fluctuations, and shear viscosity data. Using high frequency shear impedance spectrometry in the range 20-130 MHz, relaxations in the background part of the viscosity, resulting in viscoelastic mixture properties, have been found. Both series of D data agree either if a half-attenuation frequency distinctly smaller than the theoretical value Omega(1/2)=2.1 is used in the Bhattacharjee-Ferrell scaling function or if the viscosity extrapolated from the shear impedance measurements to low frequencies is applied to the Kawasaki-Ferrell relation. This extrapolated viscosity is smaller than the static shear viscosity measured with capillary viscosimeters. PMID:12935130

  5. Quantitative characterization of the viscosity of a microemulsion

    NASA Technical Reports Server (NTRS)

    Berg, Robert F.; Moldover, Michael R.; Huang, John S.

    1987-01-01

    The viscosity of the three-component microemulsion water/decane/AOT has been measured as a function of temperature and droplet volume fraction. At temperatures well below the phase-separation temperature the viscosity is described by treating the droplets as hard spheres suspended in decane. Upon approaching the two-phase region from low temperature, there is a large (as much as a factor of four) smooth increase of the viscosity which may be related to the percolation-like transition observed in the electrical conductivity. This increase in viscosity is not completely consistent with either a naive electroviscous model or a simple clustering model. The divergence of the viscosity near the critical point (39 C) is superimposed upon the smooth increase. The magnitude and temperature dependence of the critical divergence are similar to that seen near the critical points of binary liquid mixtures.

  6. Dementia and driving

    MedlinePlus

    ... getting more dangerous include: Getting lost on familiar roads Reacting more slowly in traffic Driving too slowly ... attention to traffic signs Taking chances on the road Drifting into other lanes Getting more agitated in ...

  7. Control rod drive

    SciTech Connect

    Hawke, Basil C.

    1986-01-01

    A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

  8. Drive program documentation

    NASA Technical Reports Server (NTRS)

    Graham, S.

    1979-01-01

    The program description and user's guide for the Downlist Requirement Integrated Verification and Evaluation (DRIVE) program is provided. The program is used to compare existing telemetry downlist files with updated downlist requirements.

  9. Safe driving for teens

    MedlinePlus

    ... drivers. Do not use cell phones for talking, texting, or email when you are driving. Mobile phones ... pull off of the road before answering or texting. Other tips include: Avoid putting on makeup while ...

  10. Interpretation of steam drive pilots in the Belridge Diatomite

    SciTech Connect

    Johnston, R.M.; Shahin, G.T.

    1995-12-31

    The South Belridge Diatomite Field contains more than 2.5 billion barrels of oil-in-place. Current primary and waterflood development are estimated to recover only a small fraction of this oil. Despite its low permeability, the diatomite may be a good candidate for the steam drive process, due to its thick oil column (1,000 ft), high porosity (50% to 65%), and high oil saturation (up to 70%). With these attributes, thermal expansion and decreased viscosity of reservoir fluids accelerate oil production, without significant heat loss to cap and base rock. Steam drive pilot operations have been conducted at South Belridge since 1986. This paper discusses the pilot projects and the 15-acre steam drive full-scale project currently being installed.

  11. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett Lee; Danforth, William; Bevington, Christopher; Stowell, Jesse; Costin, Daniel

    2006-09-19

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  12. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett; Danforth, William; Bevington, Christopher; Jesse, Stowell; Costin, Daniel

    2007-02-27

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  13. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett; Danforth, William; Bevington, Christopher; Stowell, Jesse; Costin, Daniel

    2006-07-11

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  14. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett; Danforth, William; Bevington, Christopher; Jesse, Stowell; Costin, Daniel

    2006-10-10

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  15. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

    BS>A drive mechanism was invented for the control rod of a nuclear reactor. Power is provided by an electric motor and an outside source of fluid pressure is utilized in conjunction with the fluid pressure within the reactor to balance the loadings on the motor. The force exerted on the drive mechanism in the direction of scramming the rod is derived from the reactor fluid pressure so that failure of the outside pressure source will cause prompt scramming of the rod.

  16. Common drive unit

    NASA Technical Reports Server (NTRS)

    Ellis, R. C.; Fink, R. A.; Moore, E. A.

    1987-01-01

    The Common Drive Unit (CDU) is a high reliability rotary actuator with many versatile applications in mechanism designs. The CDU incorporates a set of redundant motor-brake assemblies driving a single output shaft through differential. Tachometers provide speed information in the AC version. Operation of both motors, as compared to the operation of one motor, will yield the same output torque with twice the output speed.

  17. Wave anisotropy of shear viscosity and elasticity

    NASA Astrophysics Data System (ADS)

    Rudenko, O. V.; Sarvazyan, A. P.

    2014-11-01

    The paper presents the theory of shear wave propagation in a "soft solid" material possessing anisotropy of elastic and dissipative properties. The theory is developed mainly for understanding the nature of the low-frequency acoustic characteristics of skeletal muscles, which carry important diagnostic information on the functional state of muscles and their pathologies. It is shown that the shear elasticity of muscles is determined by two independent moduli. The dissipative properties are determined by the fourth-rank viscosity tensor, which also has two independent components. The propagation velocity and attenuation of shear waves in muscle depend on the relative orientation of three vectors: the wave vector, the polarization vector, and the direction of muscle fiber. For one of the many experiments where attention was distinctly focused on the vector character of the wave process, it was possible to make a comparison with the theory, estimate the elasticity moduli, and obtain agreement with the angular dependence of the wave propagation velocity predicted by the theory.

  18. Conductive polypyrrole/viscose fiber composites.

    PubMed

    Wang, Ning; Li, Guodong; Yu, Zhuo; Zhang, Xingxiang; Qi, Xiaoling

    2015-08-20

    Polypyrrole (PPy) was polymerized with pyrrole (Py) as the monomer, FeCl3 as an oxidant and sodium dodecyl benzene sulfonate (SDBS) as the dopant on the surface of viscose fiber (VCF) to prepare the conductive PPy/VCF composites. Fourier transform infrared spectra (FT-IR), thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscope (XPS) proved that the interaction between PPy and VCF formed in the PPy/VCF composites. Three structures of N atoms (imine, amine and cationic atoms) were found in PPy of PPy/VCF composites. The influence of reaction conditions including reaction time, Py concentration, FeCl3 concentration and SDBS concentration on the morphology and the conductivity of PPy/VCF composites was investigated in detail. The orthogonal experiments were designed to determine the optimal reaction conditions: reaction time 5h, Py concentration 0.1 mol/L and FeCl3 concentration 0.25 mol/L. When PPy/VCF composite was washed 50 times in water, the conductivity still kept at 1.5S/cm, and this value was stable for more washing. PMID:25965491

  19. Elongational viscosity of photo-oxidated LDPE

    SciTech Connect

    Rolón-Garrido, Víctor H. E-mail: manfred.wagner@tu-berlin.de; Wagner, Manfred H. E-mail: manfred.wagner@tu-berlin.de

    2014-05-15

    Sheets of low-density polyethylene (LDPE) were photo-oxidatively treated at room temperature, and subsequently characterized rheologically in the melt state by shear and uniaxial extensional experiments. For photo-oxidation, a xenon lamp was used to irradiate the samples for times between 1 day and 6 weeks. Linear-viscoelastic characterization was performed in a temperature range of 130 to 220°C to obtain the master curve at 170°C, the reference temperature at which the elongational viscosities were measured. Linear viscoelasticity is increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by an increasing gel fraction as determined by a solvent extraction method. The elongational measurements reveal a strong enhancement of strain hardening until a saturation level is achieved. The elongational data are analyzed in the frame work of two constitutive equations, the rubber-like liquid and the molecular stress function models. Within the experimental window, timedeformation separability is confirmed for all samples, independent of the degree of photo-oxidation.

  20. Effects of Metal Ions on Viscosity of Aqueous Sodium Carboxylmethylcellulose Solution and Development of Dropping Ball Method on Viscosity

    ERIC Educational Resources Information Center

    Set, Seng; Ford, David; Kita, Masakazu

    2015-01-01

    This research revealed that metal ions with different charges could significantly affect the viscosity of aqueous sodium carboxylmethylcellulose (CMC) solution. On the basis of an Ostwald viscometer, an improvised apparatus using a dropping ball for examining the viscosity of liquids/solutions has been developed. The results indicate that the…

  1. Self-driving carsickness.

    PubMed

    Diels, Cyriel; Bos, Jelte E

    2016-03-01

    This paper discusses the predicted increase in the occurrence and severity of motion sickness in self-driving cars. Self-driving cars have the potential to lead to significant benefits. From the driver's perspective, the direct benefits of this technology are considered increased comfort and productivity. However, we here show that the envisaged scenarios all lead to an increased risk of motion sickness. As such, the benefits this technology is assumed to bring may not be capitalised on, in particular by those already susceptible to motion sickness. This can negatively affect user acceptance and uptake and, in turn, limit the potential socioeconomic benefits that this emerging technology may provide. Following a discussion on the causes of motion sickness in the context of self-driving cars, we present guidelines to steer the design and development of automated vehicle technologies. The aim is to limit or avoid the impact of motion sickness and ultimately promote the uptake of self-driving cars. Attention is also given to less well known consequences of motion sickness, in particular negative aftereffects such as postural instability, and detrimental effects on task performance and how this may impact the use and design of self-driving cars. We conclude that basic perceptual mechanisms need to be considered in the design process whereby self-driving cars cannot simply be thought of as living rooms, offices, or entertainment venues on wheels. PMID:26446454

  2. Parkinson disease and driving

    PubMed Central

    Classen, Sherrilene; Uc, Ergun Y.

    2012-01-01

    ABSTRACT The growing literature on driving in Parkinson disease (PD) has shown that driving is impaired in PD compared to healthy comparison drivers. PD is a complex neurodegenerative disorder leading to motor, cognitive, and visual impairments, all of which can affect fitness to drive. In this review, we examined studies of driving performance (on-road tests and simulators) in PD for outcome measures and their predictors. We searched through various databases and found 25 (of 99) primary studies, all published in English. Using the American Academy of Neurology criteria, a study class of evidence was assigned (I–IV, I indicating the highest level of evidence) and recommendations were made (Level A: predictive or not; B: probably predictive or not; C: possibly predictive or not; U: no recommendations). From available Class II and III studies, we identified various cognitive, visual, and motor measures that met different levels of evidence (usually Level B or C) with respect to predicting on-road and simulated driving performance. Class I studies reporting Level A recommendations for definitive predictors of driving performance in drivers with PD are needed by policy makers and clinicians to develop evidence-based guidelines. PMID:23150533

  3. Hydraulic drive system prevents backlash

    NASA Technical Reports Server (NTRS)

    Acord, J. D.

    1965-01-01

    Hydraulic drive system uses a second drive motor operating at reduced torque. This exerts a relative braking action which eliminates the normal gear train backlash that is intolerable when driving certain heavy loads.

  4. Family Influences and Unconscious Drives.

    ERIC Educational Resources Information Center

    English, Fanita

    2001-01-01

    Drives for survival, expression, and quiescence influence early human development and continue to influence career development throughout life. Turmoil may arise when a drive conflicts with others or is suppressed by other drives. (SK)

  5. Influence of the liquid viscosity on the formation of bubble structures in a 20kHz field.

    PubMed

    Salinas, V; Vargas, Y; Louisnard, O; Gaete, L

    2015-01-01

    The cavitation field in a cylindrical vessel bottom-insonified by a 19.7kHz large area transducer is studied experimentally. By adding controlled amounts of Poly-Ethylene Glycol (PEG) to water, the viscosity of the liquid is varied between one- and nine-fold the viscosity of pure water. For each liquid, and for various displacement amplitudes of the transducer, the liquid is imaged by a high-speed camera and the acoustic field is measured along the symmetry axis. For low driving amplitudes, only a spherical cap bubble structure appears on the transducer, growing with amplitude, and the axial acoustic pressure field displays a standing-wave shape. Above some threshold amplitude of the transducer, a flare-like structure starts to build up, involving bubbles strongly expelled from the transducer surface, and the axial pressure profile becomes almost monotonic. Increasing more the driving amplitude, the structure extends in height, and the pressure profile remains monotonic but decreases its global amplitude. This behavior is similar for all the water-PEG mixtures used, but the threshold for structure formation increases with the viscosity of the liquid. The images of the bubble structures are interpreted and correlated to the measured acoustic pressure profiles. The appearance of traveling waves near the transducer, produced by the strong energy dissipated by inertial bubbles, is conjectured to be a key mechanism accompanying the sudden appearance of the flare-like structure. PMID:25082762

  6. Mental workload and driving

    PubMed Central

    Paxion, Julie; Galy, Edith; Berthelon, Catherine

    2014-01-01

    The aim of this review is to identify the most representative measures of subjective and objective mental workload in driving, and to understand how the subjective and objective levels of mental workload influence the performance as a function of situation complexity and driving experience, i.e., to verify whether the increase of situation complexity and the lack of experience increase the subjective and physiological levels of mental workload and lead to driving performance impairments. This review will be useful to both researchers designing an experimental study of mental workload and to designers of drivers’ training content. In the first part, we will broach the theoretical approach with two factors of mental workload and performance, i.e., situation complexity and driving experience. Indeed, a low complex situation (e.g., highways), or conversely a high complex situation (e.g., town) can provoke an overload. Additionally, performing the driving tasks implies producing a high effort for novice drivers who have not totally automated the driving activity. In the second part, we will focus on subjective measures of mental workload. A comparison of questionnaires usually used in driving will allow identifying the most appropriate ones as a function of different criteria. Moreover, we will review the empirical studies to verify if the subjective level of mental workload is high in simple and very complex situations, especially for novice drivers compared to the experienced ones. In the third part, we will focus on physiological measures. A comparison of physiological indicators will be realized in order to identify the most correlated to mental workload. An empirical review will also take the effect of situation complexity and experience on these physiological indicators into consideration. Finally, a more nuanced comparison between subjective and physiological measures will be established from the impact on situation complexity and experience. PMID:25520678

  7. Shear viscosity of strongly interacting fermionic quantum fluids

    NASA Astrophysics Data System (ADS)

    Pakhira, Nandan; McKenzie, Ross H.

    2015-09-01

    Eighty years ago, Eyring proposed that the shear viscosity of a liquid η has a quantum limit η ≳n ℏ where n is the density of the fluid. Using holographic duality and the anti-de Sitter/conformal field theory correspondence in string theory, Kovtun, Son, and Starinets (KSS) conjectured a universal bound η/s ≥ℏ/4 π kB for the ratio between the shear viscosity and the entropy density s . Using dynamical mean-field theory, we calculate the shear viscosity and entropy density for a fermionic fluid described by a single-band Hubbard model at half-filling. Our calculated shear viscosity as a function of temperature is compared with experimental data for liquid 3He . At low temperature, the shear viscosity is found to be well above the quantum limit and is proportional to the characteristic Fermi liquid 1 /T2 dependence, where T is the temperature. With increasing temperature and interaction strength U , there is significant deviation from the Fermi liquid form. Also, the shear viscosity violates the quantum limit near the crossover from coherent quasiparticle-based transport to incoherent transport (the bad metal regime). Finally, the ratio of the shear viscosity to the entropy density is found to be comparable to the KSS bound for parameters appropriate to liquid 3He . However, this bound is found to be strongly violated in the bad metal regime for parameters appropriate to lattice electronic systems such as organic charge-transfer salts.

  8. Development of viscosity sensor with long period fiber grating technology

    NASA Astrophysics Data System (ADS)

    Lin, Jyh-Dong; Wang, Jian-Neng; Chen, Shih-Huang; Wang, Juei-Mao

    2009-03-01

    In this paper, we describe the development of a viscosity sensing system using a simple and low-cost long-period fiber grating (LPFG) sensor. The LPFG sensor was extremely sensitive to the refractive index of the medium surrounding the cladding surface of the sensing grating, thus allowing it to be used as an ambient index sensor or chemical concentration indicator. Viscosity can be simply defined as resistance to flow of a liquid. We have measured asphalt binder, 100-190000 centistokes, in comparison with optical sensing results. The system sensing asphalt binders exhibited increase trend in the resonance wavelength shift when the refractive index of the medium changed. The prototype sensor consisted of a LPFG sensing component and a cone-shaped reservoir where gravitational force can cause asphalt binders flow through the capillary. Thus the measured time for a constant volume of asphalt binders can be converted into either absolute or kinematic viscosity. In addition, a rotational viscometer and a dynamic shear rheometer were also used to evaluate the viscosity of this liquid, the ratio between the applied shear stress and rate of shear, as well as the viscoelastic property including complex shear modulus and phase angle. The measured time could be converted into viscosity of asphalt binder based on calculation. This simple LPFG viscosity sensing system is hopefully expected to benefit the viscosity measurement for the field of civil, mechanical and aerospace engineering.

  9. GodunovSPH with shear viscosity: implementation and tests

    NASA Astrophysics Data System (ADS)

    Cha, Seung-Hoon; Wood, Matt A.

    2016-05-01

    The acceleration and energy dissipation terms due to the shear viscosity have been implemented and tested in GodunovSPH. The double summation method has been employed to avoid the well-known numerical noise of the second derivative in particle based codes. The plane Couette flow with various initial and boundary conditions have been used as tests, and the numerical and analytical results show a good agreement. Not only the viscosity-only calculation, but the full hydrodynamics simulations have been performed, and they show expected results as well. The very low kinematic viscosity simulations show a turbulent pattern when the Reynolds number exceeds ˜102. The critical value of the Reynolds number at the transition point of the laminar and turbulent flows coincides with the previous works approximately. A smoothed dynamic viscosity has been suggested to describe the individual kinematic viscosity of particles. The infinitely extended Couette flow which has two layers of different viscosities has been simulated to check the smoothed dynamic viscosity, and the result agrees well with the analytic solution. In order to compare the standard smoothed particle hydrodynamics (SPH) and GodunovSPH, the two layers test has been performed again with a density contrast. GodunovSPH shows less dispersion than the standard SPH, but there is no significant difference in the results. The results of the viscous ring evolution has also been presented as well, and the numerical results agrees with the analytic solution.

  10. Reducing the Viscosity of Blood by Pulsed Magnetic Field

    NASA Astrophysics Data System (ADS)

    Tao, R.; Huang, K.

    2010-03-01

    Blood viscosity is a major player in heart disease. When blood is viscous, in addition to a high blood pressure required for the blood circulation, blood vessel walls are also easy to be damaged. While this issue is very important, currently the only method to reduce the blood viscosity is to take medicine, such as aspirin. Here we report our new finding that the blood viscosity can be reduced by pulsed magnetic field. Blood is a suspension of red blood cells (erythrocytes), white blood cells (leukocytes) and platelets in plasma, a complex solution of gases, salts, proteins, carbohydrates, and lipids. The base liquid, plasma, has low viscosity. The effective viscosity of whole blood increases mainly due to the red blood cells, which have a volume fraction about 40% or above. Red blood cells contain iron and are sensitive to magnetic field. Therefore, when we apply a strong magnetic field, the red cells make their diameters align in the field direction to form short chains. This change in rheology reduces the effective viscosity as high as 20-30%. While this reduction is not permanent, it lasts for several hours and repeatable. The reduction rate can be controlled by selecting suitable magnetic field and duration of field application to make blood viscosity within the normal range.

  11. Low viscosity highly concentrated injectable nonaqueous suspensions of lysozyme microparticles.

    PubMed

    Miller, Maria A; Engstrom, Joshua D; Ludher, Baltej S; Johnston, Keith P

    2010-01-19

    Subcutaneous injection of concentrated protein and peptide solutions, in the range of 100-400 mg/mL, is often not possible with a 25- to 27-gauge needle, as the viscosity can be well above 50 cP. Apparent viscosities below this limit are reported for suspensions of milled lysozyme microparticles up to nearly 400 mg/mL in benzyl benzoate or benzyl benzoate mixtures with safflower oils through a syringe with a 25- to 27-gauge needle at room temperature. These apparent viscosities were confirmed using a cone-and-plate rheometer. The intrinsic viscosity regressed from the Kreiger-Dougherty model was only slightly above the Einstein value of 2.5, indicating the increase in viscosity relative to that of the solvent was caused primarily by the excluded volume. Thus, the increases in viscosity from electrical double layer interactions (electroviscous effects), solvation of the particles, or deviations of the particle shape from a spherical geometry were minimal, and much smaller than typically observed for proteins dissolved in aqueous solutions. The small electroviscous effects are expected given the negligible zeta potential and thin double layers in the low dielectric constant organic solvent. The suspensions were resuspendable after a year, with essentially constant particle size after two months as measured by static light scattering. The lower apparent viscosities for highly concentrated protein suspensions relative to protein solutions, coupled with these favorable characteristics upon resuspension, may offer novel opportunities for subcutaneous injection of therapeutic proteins. PMID:19803503

  12. Viscosity model for pure gases at atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Miadonye, Adango; McKenna, Tara M.

    2005-06-01

    The production processes for petroleum gases use a broad range of simulation packages to reduce the capital, time, and cost associated with actual recovery and pipeline transportation. The viscosity model is an important component of these packages. In this study, two simple-to-use empirical models are presented for predicting the viscosity of petroleum gases: the three-parameter Yaws equation; and the correlation of Miadonye-Clyburn. New values were obtained for the constants in Yaws’ equation for various hydrocarbon gases. Alternatively, the Yaws equation has been extended to cover nonhydrocarbon gases, some for the first time, and new values were derived for the constants for these gases. The results obtained with the new constants were compared with the viscosity predictions from both the Yaws and the Miadonye-Clyburn correlations. For four petroleum gases and two nonhydrocarbon gases at temperatures from 100 to 1500 K, the models gave viscosity predictions with overall average absolute deviations of 0.30 and 0.75% for the Yaws correlation with new constants, and 1.17 and 2.7% for the Miadonye-Clyburn correlation for viscosity predictions based on one viscosity value. Both models are simple to incorporate in design and simulation packages, and are accurate within the limits of experimental errors for the viscosities of petroleum gases.

  13. Influence of CaF2 on the Viscosity and Structure of Manganese Ferroalloys Smelting Slags

    NASA Astrophysics Data System (ADS)

    Park, Joo Hyun; Ko, Kyu Yeol; Kim, Tae Sung

    2015-04-01

    Addition of CaF2 to the CaO-SiO2-MnO (CaO/SiO2 = 0.5) system, which corresponds qualitatively to a silicomanganese ferroalloy smelting slag, affected not only the critical (crystallization) temperature ( T CR) but also the viscosity at high temperatures, and its influence on slag properties was strongly dependent on the content of MnO in the slag. The viscosity of CaF2-free 10 mass pct MnO slag was relatively high, i.e., about 10 dPa s at 1773 K (1500 °C), but decreased continuously upon addition of CaF2 to the system. In contrast, the viscosity of the 40 pct MnO system was very low, i.e., 1 dPa s at 1773 K (1500 °C), and CaF2 did not have a large effect. This indicates that Mn2+ is a strong network modifier in manganese ferroalloy smelting slags. Nevertheless, CaF2 addition was very effective at decreasing the viscosity of low MnO slags at low temperatures. The activation energy for the viscous flow of silicate melts decreased linearly in response to CaF2 addition, but this tendency was less pronounced in the more basic composition of the slag. The effect of CaF2 on the viscosity and activation energy for viscous flow of melts was analyzed quantitatively using micro-Raman spectra of quenched glass samples and the silicate polymerization index, i.e., Q3/Q2 ratio. The polymerization index decreased continuously with increasing CaF2 content in less basic (10 pct MnO or C/S = 0.5) slags, whereas it was not affected by CaF2 content in highly basic (40 pct MnO and C/S = 1.0) slags. Bulk thermophysical properties of the CaO-SiO2-MnO-CaF2 slags were quantitatively correlated with the structural information of the slags.

  14. Bulk materials handling equipment roundup

    SciTech Connect

    Fiscor, S.

    2007-07-15

    The article reports recent product developments in belt conveyors. Flexco Steel Lancing Co. (Flexco) has a range of light, portable maintenance tools and offers training modules on procedures for belt conveyor maintenance on its website www.flexcosafe.com. Siemens recently fitted a 19 km long conveyor belt drive system at a Texan aluminium plant with five 556-kW Simovent Masterdrive VC drives. Voith recently launched the TPKL-T turbo coupling for users who want an alignment-free drive solution. Belt cleaners newly on the market include the RemaClean SGB brush and ASGCO Manufacturing's Razor-Back with Spray bar. Continental Conveyor has introduced a new line of dead-shaft pulleys offering increased bearing protection. 6 photos.

  15. Blood viscosity in tube flow: dependence on diameter and hematocrit.

    PubMed

    Pries, A R; Neuhaus, D; Gaehtgens, P

    1992-12-01

    Since the original publications by Martini et al. (Dtsch. Arch. Klin. Med. 169: 212-222, 1930) and Fahraeus and Lindqvist (Am. J. Physiol. 96: 562-568, 1931), it has been known that the relative apparent viscosity of blood in tube flow depends on tube diameter. Quantitative descriptions of this effect and of the dependence of blood viscosity on hematocrit in the different diameter tubes are required for the development of hydrodynamic models of blood flow through the microcirculation. The present study provides a comprehensive data base for the description of relative apparent blood viscosity as a function of tube diameter and hematocrit. Data available from the literature are compiled, and new experimental data obtained in a capillary viscometer are presented. The combined data base comprises measurements at high shear rates (u > or = 50 s-1) in tubes with diameters ranging from 3.3 to 1,978 microns at hematocrits of up to 0.9. If corrected for differences in suspending medium viscosity and temperature, the data show remarkable agreement. Empirical fitting equations predicting relative apparent blood viscosity from tube diameter and hematocrit are presented. A pronounced change in the hematocrit dependence of relative viscosity is observed in a range of tube diameters in which viscosity is minimal. While a linear hematocrit-viscosity relationship is found in tubes of < or = 6 microns, an overproportional increase of viscosity with hematocrit prevails in tubes of > or = 9 microns. This is interpreted to reflect the hematocrit-dependent transition from single- to multifile arrangement of cells in flow. PMID:1481902

  16. Effect of viscosity on metachrony in mucus propelling cilia.

    PubMed

    Gheber, L; Korngreen, A; Priel, Z

    1998-01-01

    In the present work we report that increasing the viscosity of the medium caused not only a decrease in the ciliary beat frequency but also changes in the metachrony and correlation between cilia. The study was performed using double and triple simultaneous photoelectric measurements on cultured ciliary cells from the frog esophagus in the viscosity range of 1-2,000 cp. We observed that increasing the viscosity intensified the fluctuations in all the measured parameters. Ciliary beat frequency decreased moderately. Even at quite high viscosities (circa 2000 cp.), cilia were still active with beating frequencies of 3-5 Hz. In addition, the degree of correlation between cilia parallel to the effective stroke direction (ESD) decreased, while that perpendicular to the ESD at a low range of viscosities remained unchanged and even increased at high viscosities. Medium viscosities in the range of 30-1,500 cp. altered the metachronal wave properties of cultured frog esophagus. The metachronal wavelength increased by up to 50%, and the wave direction changed towards more orthoplectic type of coordination. According to our recently suggested model [Gheber and Priel, 1990: Cell Motil. Cytoskeleton 16:167-181], these effects can be explained by a decrease in the temporal asymmetry of the ciliary beat. Since similar results were observed in water propelling cilia of Paramecium subjected to medium viscosity ranges of up to 40 cp. [Machemer, 1972: J. Exp. Biol. 57:239-259], we conclude that hydrodynamic interactions govern the metachronal wave properties of both mucus and water propelling cilia, though mucus propelling cilia, with their better adaptation to increased load, are affected at much higher viscosities than water propelling cilia. PMID:9453710

  17. Driving Anger and Driving Behavior in Adults with ADHD

    ERIC Educational Resources Information Center

    Richards, Tracy L.; Deffenbacher, Jerry L.; Rosen, Lee A.; Barkley, Russell A.; Rodricks, Trisha

    2006-01-01

    Objective: This study assesses whether anger in the context of driving is associated with the negative driving outcomes experienced by individuals with ADHD. Method: ADHD adults (n = 56) complete measures of driving anger, driving anger expression, angry thoughts behind the wheel, and aggressive, risky, and crash-related behavior. Results are…

  18. Measurements of nanofluid viscosity and its implications for thermal applications

    NASA Astrophysics Data System (ADS)

    Prasher, Ravi; Song, David; Wang, Jinlin; Phelan, Patrick

    2006-09-01

    Experimental results on the viscosity of alumina-based nanofluids are reported for various shear rates, temperature, nanoparticle diameter, and nanoparticle volume fraction. From the data it seems that the increase in the nanofluid viscosity is higher than the enhancement in the thermal conductivity as reported in the literature. It is shown, however, that the viscosity has to be increased by more than a factor of 4—relative to the increase in thermal conductivity—to make the nanofluid thermal performance worse than that of the base fluid.

  19. Experimental investigation of nanofluid shear and longitudinal viscosities

    NASA Astrophysics Data System (ADS)

    Schmidt, Aaron J.; Chiesa, Matteo; Torchinsky, Darius H.; Johnson, Jeremy A.; Boustani, Avid; McKinley, Gareth H.; Nelson, Keith A.; Chen, Gang

    2008-06-01

    Dilute nanoparticle suspensions of alumina in decane and isoparaffinic polyalphaolefin (PAO) exhibit thermal conductivity and shear viscosity that are enhanced compared to continuum models that assume well-dispersed particles. An optical technique has been used to measure the longitudinal viscosity of these suspensions at frequencies from 200to600MHz and evaluate an effective hydrodynamic particle size. The measurements indicate that for the decane-based nanofluids the nanoparticles do not form clusters. In the case of PAO nanofluids, the measurements of longitudinal viscosity and the corresponding values of the particle size are consistent with a picture of nonclustered particles in a weakly shear-thinning viscous oligomeric oil.

  20. Densities and viscosities of supersaturated potash alum aqueous solutions

    NASA Astrophysics Data System (ADS)

    Kubota, Noriaki; Shimizu, Kenji; Itagaki, Hideo

    1985-11-01

    Densities and relative viscosities have been determined for solutions of different concentrations over a wide range of temperatures from the undercooled to the supercooled region. Neither the densities nor the relative viscosities show any sudden change even in the supercooled state, but they gradually and continuously change with temperature from the undercooled to the supercooled region. This is important for practical use, since it makes it possible to estimate these physical properties in the supercooled region by extrapolating data in the undercooled region. Experimental equations which give the densities and the relative viscosities were obtained as a function of temperature and of saturation temperature.

  1. Shear viscosities of photons in strongly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Yang, Di-Lun; Müller, Berndt

    2016-09-01

    We investigate the shear viscosity of thermalized photons in the quark gluon plasma (QGP) at weak coupling and N = 4 super Yang-Mills plasma (SYMP) at both strong and weak couplings. We find that the shear viscosity due to the photon-parton scattering up to the leading order of electromagnetic coupling is suppressed when the coupling of the QGP/SYMP is increased, which stems from the blue-shift of the thermal-photon spectrum at strong coupling. In addition, the shear viscosity rapidly increases near the deconfinement transition in a phenomenological model analogous to the QGP.

  2. Fiber optic sensor for flow and viscosity measurement

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Leang, Jonathan

    2016-04-01

    A sensitive fluid viscosity and flow measurement device using optical intensity based sensing is presented. The sensing principle makes use of the damping characteristic of a vibrating optical fiber probe with approximate hinge-free end configuration. The viscosity and mass flow are determined by measuring the vibration of a sinusoidally excited tapered optical fiber under different flow conditions. By measuring the frequency response of the fiber probe, viscosity and mass flow can be deduced from the damping coefficient of the response. The concepts and experimental data presented demonstrate and refine the sensing process of the proposed system.

  3. Liquid drop model of spherical nuclei with account of viscosity

    NASA Astrophysics Data System (ADS)

    Khokonov, A. Kh.

    2016-01-01

    In the frame of nuclear liquid drop model an analytical solution for the frequency of capillary oscillations is obtained with taking into account the damping due to viscosity and surrounding medium polarizability. The model has been applied for estimation of even-even spherical nuclei surface tension and viscosity. It has been shown that energy shift of capillary oscillations of even-even spherical nuclei due to viscous dissipation gives viscosities in the interval 4.2- 7.6 MeVfm-2c-1 for nuclei from 10646Pd to 19880Hg.

  4. Self-calibrating viscosity probes: Design and subcellular localization

    PubMed Central

    Dakanali, Marianna; Do, Thai H.; Horn, Austin; Chongchivivat, Akaraphon; Jarusreni, Tuptim; Lichlyter, Darcy; Guizzunti, Gianni; Haidekker, Mark A.; Theodorakis, Emmanuel A.

    2012-01-01

    We describe the design, synthesis and fluorescence profiles of new self-calibrating viscosity dyes in which a coumarin (reference fluorophore) has been covalently linked with a molecular rotor (viscosity sensor). Characterization of their fluorescence properties was made with separate excitation of the units and through Resonance Energy Transfer from the reference to the sensor dye. We have modified the linker and the substitution of the rotor in order to change the hydrophilicity of these probes thereby altering their subcellular localization. For instance, hydrophilic dye 12 shows a homogeneous distribution inside the cell and represents a suitable probe for viscosity measurements in the cytoplasm. 2012 Elsevier Ltd. All rights reserved. PMID:22698784

  5. Astronaut Mike Fincke Conducts Fluid Merging Viscosity Measurement (FMVM) Experiment

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Astronaut Mike Fincke places droplets of honey onto the strings for the Fluid Merging Viscosity Measurement (FMVM) investigation onboard the International Space Station (ISS). The FMVM experiment measures the time it takes for two individual highly viscous fluid droplets to coalesce or merge into one droplet. Different fluids and droplet size combinations were tested in the series of experiments. By using the microgravity environment, researchers can measure the viscosity or 'thickness' of fluids without the influence of containers and gravity using this new technique. Understanding viscosity could help scientists understand industrially important materials such as paints, emulsions, polymer melts and even foams used to produce pharmaceutical, food, and cosmetic products.

  6. Viscosity of Liquid Crystal Mixtures in the Presence of Electroconvection

    NASA Astrophysics Data System (ADS)

    Nagaya, Tomoyuki; Satou, Yuki; Goto, Yoshitomo; Hidaka, Yoshiki; Orihara, Hiroshi

    2016-07-01

    We have experimentally investigated the viscosity of nematic liquid crystal mixtures of p-methoxybenzylidene-p'-n-butylaniline (MBBA) and p-ethoxybenzylidene-p'-cyanoaniline (EBCA) in the presence of electroconvection under an ac electric field with 60 Hz. Although the viscosity of the mixtures with negative dielectric anisotropy shows a characteristic decrease in the high-voltage regime, that with positive dielectric anisotropy shows a monotonic increase as the applied voltage is increased. The experimental results suggest that the decrease in viscosity observed only for the mixtures with negative dielectric anisotropy is attributed to the negative contribution of electric stress caused by the anisotropic director distribution of the turbulent state.

  7. Molecular rotors: Synthesis and evaluation as viscosity sensors

    PubMed Central

    Sutharsan, Jeyanthy; Lichlyter, Darcy; Wright, Nathan E.; Dakanali, Marianna; Haidekker, Mark A.; Theodorakis, Emmanuel A.

    2010-01-01

    It has been shown that compounds containing the p-N,N,-dialkylaminobenzylidene cyanoacetate motif can serve as fluorescent non-mechanical viscosity sensors. These compounds, referred to as molecular rotors, belong to a class of fluorescent probes that are known to form twisted intramolecular charge-transfer complexes in the excited state. In this study we present the synthesis and spectroscopic characterization of these compounds as viscosity sensors. The effects of the molecular structure and electronic density of these rotors to the emission wavelength, fluorescence intensity and viscosity sensitivity are discussed. PMID:20694175

  8. On the Role of Viscosity in the Eyring Equation.

    PubMed

    Kistemaker, Jos C M; Lubbe, Anouk S; Bloemsma, Erik A; Feringa, Ben L

    2016-06-17

    Transition-state theory allows for the characterization of kinetic processes in terms of enthalpy and entropy of activation by using the Eyring equation. However, for reactions in solution, it fails to take the change of viscosity of solvents with temperature into account. A second-generation unidirectional rotary molecular motor was used as a probe to study the effects of temperature-dependent viscosity changes upon unimolecular thermal isomerization processes. By combining the free-volume model with transition-state theory, a modified version of the Eyring equation was derived, in which the rate is expressed in terms of both temperature and viscosity. PMID:26853537

  9. Driving anger in Malaysia.

    PubMed

    Sullman, Mark J M; Stephens, Amanda N; Yong, Michelle

    2014-10-01

    The present study examined the types of situations that cause Malaysian drivers to become angry. The 33-item version of the driver anger scale (Deffenbacher et al., 1994) was used to investigate driver anger amongst a sample of 339 drivers. Confirmatory factor analysis showed that the fit of the original six-factor model (discourtesy, traffic obstructions, hostile gestures, slow driving, illegal driving and police presence), after removing one item and allowing three error pairs to covary, was satisfactory. Female drivers reported more anger, than males, caused by traffic obstruction and hostile gestures. Age was also negatively related to five (discourtesy, traffic obstructions, hostile gestures, slow driving and police presence) of the six factors and also to the total DAS score. Furthermore, although they were not directly related to crash involvement, several of the six forms of driving anger were significantly related to the crash-related conditions of: near misses, loss of concentration, having lost control of a vehicle and being ticketed. Overall the pattern of findings made in the present research were broadly similar to those from Western countries, indicating that the DAS is a valid measure of driving anger even among non-European based cultures. PMID:24863369

  10. [Drug use and driving].

    PubMed

    Lemaire-Hurtel, Anne-Sophie; Goullé, Jean-Pierre; Alvarez, Jean-Claude; Mura, Patrick; Verstraete, Alain G

    2015-10-01

    Some drugs are known to impair driving because they can change the vision or hearing, and/or disrupt the intellectual or motor abilities: impaired vigilance, sedation, disinhibition effect, the coordination of movement disorders and the balance. The doctor during prescribing and the pharmacist during deliverance of drug treatment should inform their patients of the potential risks of drugs on driving or operating machinery. The driver has direct responsibility, who hired him and him alone, to follow the medical advice received. The pictograms on the outer packaging of medicinal products intended to classify substances according to their risk driving: The driver can whether to observe simple precautions (level one "be prudent"), or follow the advice of a health professional (level two "be very careful"), or if it is totally not drive (level three "danger caution: do not drive"). This classification only evaluates the intrinsic danger of drugs but not the individual variability. Medicines should be taken into account also the conditions for which the medication is prescribed. It is important to inform the patient on several points. PMID:25956300

  11. Methods of synthesizing hydroxyapatite powders and bulk materials

    DOEpatents

    Luo, P.

    1999-01-12

    Methods are provided for producing non-porous controlled morphology hydroxyapatite granules of less than 8 {micro}m by a spray-drying process. Solid or hollow spheres or doughnuts can be formed by controlling the volume fraction and viscosity of the slurry as well as the spray-drying conditions. Methods of providing for homogeneous cellular structure hydroxyapatite granules are also provided. Pores or channels or varying size and number can be formed by varying the temperature at which a hydroxyapatite slurry formed in basic, saturated ammonium hydroxide is spray-dried. Methods of providing non-porous controlled morphology hydroxyapatite granules in ammonium hydroxide are also provided. The hydroxyapatite granules and bulk materials formed by these methods are also provided. 26 figs.

  12. Methods of synthesizing hydroxyapatite powders and bulk materials

    DOEpatents

    Luo, Ping

    1999-01-12

    Methods are provided for producing non-porous controlled morphology hydroxyapatite granules of less than 8 .mu.m by a spray-drying process. Solid or hollow spheres or doughnuts can be formed by controlling the volume fraction and viscosity of the slurry as well as the spray-drying conditions. Methods of providing for homogenous cellular structure hydroxyapatite granules are also provided. Pores or channels or varying size and number can be formed by varying the temperature at which a hydroxyapatite slurry formed in basic, saturated ammonium hydroxide is spray-dried. Methods of providing non-porous controlled morphology hydroxyapatite granules in ammonium hydroxide are also provided. The hydroxyapatite granules and bulk materials formed by these methods are also provided.

  13. Bulk charges in eleven dimensions

    NASA Astrophysics Data System (ADS)

    Hawking, S. W.; Taylor-Robinson, M. M.

    1998-07-01

    Eleven dimensional supergravity has electric type currents arising from the Chern-Simon and anomaly terms in the action. However the bulk charge integrates to zero for asymptotically flat solutions with topological trivial spatial sections. We show that by relaxing the boundary conditions to generalisations of the ALE and ALF boundary conditions in four dimensions one can obtain static solutions with a bulk charge. Solutions involving anomaly terms preserve between 1/16 and 1/4 of the supersymmetries but Chern-Simons fluxes generally break all of the remaining supersymmetry. One can introduce membranes with the same sign of charge into these backgrounds. This raises the possibility that these generalized membranes might decay quantum mechanically to leave just a bulk distribution of charge. Alternatively and more probably, a bulk distribution of charge can decay into a collection of singly charged membranes. Dimensional reductions of these solutions lead to novel representations of extreme black holes in four dimensions with up to four charges. We discuss how the eleven-dimensional Kaluza-Klein monopole wrapped around a space with non-zero first Pontryagin class picks up an electric charge proportional to the Pontryagin number.

  14. REL - English Bulk Data Input.

    ERIC Educational Resources Information Center

    Bigelow, Richard Henry

    A bulk data input processor which is available for the Rapidly Extensible Language (REL) English versions is described. In REL English versions, statements that declare names of data items and their interrelationships normally are lines from a terminal or cards in a batch input stream. These statements provide a convenient means of declaring some…

  15. Hanford Bulk Vitrification Technology Status

    SciTech Connect

    Witwer, Keith S.; Dysland, Eric J.; Bagaasen, Larry M.; Schlahta, Stephan N.; Kim, Dong-Sang; Schweiger, Michael J.; Hrma, Pavel R.

    2007-01-25

    Research and testing was initiated in 2003 to support the selection of a supplemental treatment technology for Hanford low-activity wastes (LAWs). AMEC’s bulk vitrification process was chosen for full-scale demonstration, and the Demonstration Bulk Vitrification System (DBVS) project was started in 2004. Also known as in-container vitrification™ (ICV™), the bulk vitrification process combines soil, liquid LAW, and additives (B2O3 and ZrO2); dries the mixture; and then vitrifies the material in a batch feed-while-melt process in a refractory lined steel container. The DBVS project was initiated with the intent to engineer, construct, and operate a full-scale bulk vitrification pilot-plant to treat LAW from Tank 241-S-109 at the U.S. Department of Energy (DOE) Hanford Site. AMEC is adapting its ICV™ technology for this application with technical and analytical support from Pacific Northwest National Laboratory (PNNL). The DBVS project is funded by the DOE Office of River Protection and administered by CH2M HILL Hanford Group, Inc. Since the beginning of the selection process in 2003, testing has utilized crucible-scale, engineering-scale, and full-scale bulk vitrification equipment. Crucible-scale testing, coupled with engineering-scale testing, helps establish process limitations of selected glass formulations. Full-scale testing provides critical design verification of the ICV™ process both before and during operation of the demonstration facility. Initial testing focused on development and validation of the baseline equipment configuration and glass formulation. Subsequent testing was focused on improvements to the baseline configuration. Many improvements have been made to the bulk vitrification system equipment configuration and operating methodology since its original inception. Challenges have been identified and met as part of the parallel testing and design process. A 100% design package for the pilot plant is complete and has been submitted to DOE

  16. Ceramic vane drive joint

    DOEpatents

    Smale, Charles H.

    1981-01-01

    A variable geometry gas turbine has an array of ceramic composition vanes positioned by an actuating ring coupled through a plurality of circumferentially spaced turbine vane levers to the outer end of a metallic vane drive shaft at each of the ceramic vanes. Each of the ceramic vanes has an end slot of bow tie configuration including flared end segments and a center slot therebetween. Each of the vane drive shafts has a cross head with ends thereof spaced with respect to the sides of the end slot to define clearance for free expansion of the cross head with respect to the vane and the cross head being configured to uniformly distribute drive loads across bearing surfaces of the vane slot.

  17. U.S. DRIVE

    SciTech Connect

    2012-03-16

    U.S. DRIVE, which stands for United States Driving Research and Innovation for Vehicle efficiency and Energy sustainability, is an expanded government-industry partnership among the U.S. Department of Energy; USCAR, representing Chrysler Group LLC, Ford Motor Company and General Motors; Tesla Motors; five energy companies – BP America, Chevron Corporation, ConocoPhillips, ExxonMobil Corporation, and Shell Oil Products US; two utilities – Southern California Edison and Michigan-based DTE Energy; and the Electric Power Research Institute (EPRI). The U.S. DRIVE mission is to accelerate the development of pre-competitive and innovative technologies to enable a full range of affordable and clean advanced light-duty vehicles, as well as related energy infrastructure.

  18. Influence of Kinetic and Thermodynamic Factors on the Glass-Forming Ability of Zirconium-Based Bulk Amorphous Alloys

    SciTech Connect

    Mukherjee, S.; Johnson, W.L.; Rhim, W.-K.; Schroers, J.

    2005-06-24

    The time-temperature-transformation curves for three zirconium-based bulk amorphous alloys are measured to identify the primary factors influencing their glass-forming ability. The melt viscosity is found to have the most pronounced influence on the glass-forming ability compared to other thermodynamic factors. Surprisingly, it is found that the better glass former has a lower crystal-melt interfacial tension. This contradictory finding is explained by the icosahedral short-range order of the undercooled liquid, which on one hand reduces the interfacial tension, while on the other hand increases its viscosity.

  19. LCLS Injector Drive Laser

    SciTech Connect

    Dowell, D.H.; Castro, J.; Emma, P.; Frisch, J.; Gilevich, A.; Hays, G.; Hering, P.; Limborg-Deprey, C.; Loos, H.; Miahnahri, A.; White, W.; /SLAC

    2007-11-02

    Requirements for the LCLS injector drive laser present significant challenges to the design of the system. While progress has been demonstrated in spatial shape, temporal shape, UV generation and rep-rate, a laser that meets all of the LCLS specifications simultaneously has yet to be demonstrated. These challenges are compounded by the stability and reliability requirements. The drive laser and transport system has been installed and tested. We will report on the current operational state of the laser and plans for future improvements.

  20. Optotech 5984 Drive Overview

    NASA Astrophysics Data System (ADS)

    Lee, Tzuo-Chang; Chen, Di

    1987-01-01

    We present in this paper an overview of Optotech's 5984 Optical Disk Drive. Key features such as the modulation code, the disk format, defect mapping scheme and the optical head and servo subsystem will be singled out for discussion. Description of Optotech's 5984 disk drive The Optotech 5984 optical disk drive is a write-once-read-mostly (WORM) rotating optical memory with 200 Megabyte capacity on each side of the disk. It has a 5 1/4 inch form factor that will fit into any personal computer full-height slot. The drive specification highlights are given in Table 1. A perspective view of the drive mechanical assembly is shown in Figure 1. The spindle that rotates the disk has a runout of less than 10 um. The rotational speed at 1200 revolutions per minute (rpm) is held to an accuracy of 10-3. The total angular tolerance from perfect perpendicular alignment between the rotating disk and the incident optical beam axis is held to less than 17 milliradians. The coarse seek is accomplished through a stepping motor driving the optical head with 1.3 milliseconds per step or 32 tracks per step. The analog channels including read/write, the phase lock loop and the servo loops for focus and track control are contained on one surface mount pc board while the digital circuitry that interfaces with the drive and the controller is on a separate pc board. A microprocessor 8039 is used to control the handshake and the sequence of R/W commands. A separate power board is used to provide power to the spindle and the stepping motors. In the following we will discuss some of the salient features in the drive and leave the details to three accompanying Optotech papers. These salient features are derived from a design that is driven by three major considerations. One is precise control of the one micron diameter laser spot to any desired location on the disk. The second consideration is effective management of media defects. Given the state of the art of the Te-based disk technology with

  1. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

    Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

  2. Diffusion coefficient and shear viscosity of rigid water models.

    PubMed

    Tazi, Sami; Boţan, Alexandru; Salanne, Mathieu; Marry, Virginie; Turq, Pierre; Rotenberg, Benjamin

    2012-07-18

    We report the diffusion coefficient and viscosity of popular rigid water models: two non-polarizable ones (SPC/E with three sites, and TIP4P/2005 with four sites) and a polarizable one (Dang-Chang, four sites). We exploit the dependence of the diffusion coefficient on the system size (Yeh and Hummer 2004 J. Phys. Chem. B 108 15873) to obtain the size-independent value. This also provides an estimate of the viscosity of all water models, which we compare to the Green-Kubo result. In all cases, a good agreement is found. The TIP4P/2005 model is in better agreement with the experimental data for both diffusion and viscosity. The SPC/E and Dang-Chang models overestimate the diffusion coefficient and underestimate the viscosity. PMID:22739097

  3. Experimental Study of Additives on Viscosity biodiesel at Low Temperature

    NASA Astrophysics Data System (ADS)

    Fajar, Berkah; Sukarno

    2015-09-01

    An experimental investigation was performed to find out the viscosity of additive and biodiesel fuel mixture in the temperature range from 283 K to 318 K. Solutions to reduce the viscosity of biodiesel is to add the biodiesel with some additive. The viscosity was measured using a Brookfield Rheometer DV-II. The additives were the generic additive (Diethyl Ether/DDE) and the commercial additive Viscoplex 10-330 CFI. Each biodiesel blends had a concentration of the mixture: 0.0; 0.25; 0.5; 0.75; 1.0; and 1.25% vol. Temperature of biodiesel was controlled from 40°C to 0°C. The viscosity of biodiesel and additive mixture at a constant temperature can be approximated by a polynomial equation and at a constant concentration by exponential equation. The optimum mixture is at 0.75% for diethyl ether and 0.5% for viscoplex.

  4. Viscosity measurements of metallic melts using the oscillating drop technique

    NASA Astrophysics Data System (ADS)

    Heintzmann, P.; Yang, F.; Schneider, S.; Lohöfer, G.; Meyer, A.

    2016-06-01

    By means of benchmarking reduced gravity experiments, we have verified the measured viscosity of binary Zr-Ni glass forming liquids utilizing the oscillating drop technique combined with ground-based electrostatic levitation (ESL). Reliable viscosity data can be obtained as long as internal viscous damping of a single oscillation mode of a levitated drop dominates external perturbations. This can be verified by the absence of a sample mass dependence of the results. Hence, ESL is an excellent tool for studying the viscosity of metallic glass forming melts in the range of about 10-250 mPa s, with sample masses below 100 mg. To this end, we show that, for binary Zr-Ni melts, the viscosity is qualitatively controlled by the packing density.

  5. Laboratory Procedures in Thermal Expansion and Viscosity of Liquids

    ERIC Educational Resources Information Center

    Dawson, Paul Dow

    1974-01-01

    Describes the laboratory procedures for the measurement of thermal expansion and viscosity of liquids. These experiments require inexpensive equipment and are suitable for secondary school physical science classes. (JR)

  6. Utilization of Low Gravity Environment for Measuring Liquid Viscosity

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.; Ethridge, Edwin

    1998-01-01

    The method of drop coalescence is used for determining the viscosity of highly viscous undercooled liquids. Low gravity environment is necessary in order to allow for examining large volumes affording much higher accuracy for the viscosity calculations than possible for smaller volumes available under 1 - g conditions. The drop coalescence method is preferred over the drop oscillation technique since the latter method can only be applied for liquids with vanishingly small viscosities. The technique developed relies on both the highly accurate solution of the Navier-Stokes equations as well as on data from experiments conducted in near zero gravity environment. Results are presented for method validation experiments recently performed on board the NASA/KC-135 aircraft. While the numerical solution was produced using the Boundary Element Method. In these tests the viscosity of a highly viscous liquid, glycerine at room temperature, was determined using the liquid coalescence method. The results from these experiments will be discussed.

  7. Relating Fresh Concrete Viscosity Measurements from Different Rheometers

    PubMed Central

    Ferraris, Chiara F.; Martys, Nicos S.

    2003-01-01

    Concrete rheological properties need to be properly measured and predicted in order to characterize the workability of fresh concrete, including special concretes such as self-consolidating concrete (SCC). It was shown by a round-robin test held in 2000 [1,2] that different rheometer designs gave different values of viscosity for the same concrete. While empirical correlation between different rheometers was possible, for a procedure that is supposed to “scientifically” improve on the empirical slump tests, this situation is unsatisfactory. To remedy this situation, a new interpretation of the data was developed. In this paper, it is shown that all instruments tested could be directly and quantitatively compared in terms of relative plastic viscosity instead of the plastic viscosity alone. This should eventually allow the measurements from various rheometer designs to be directly calibrated against known standards of plastic viscosity, putting concrete rheometry and concrete workability on a sounder materials science basis.

  8. Measurements of fluid viscosity using a miniature ball drop device

    NASA Astrophysics Data System (ADS)

    Tang, Jay X.

    2016-05-01

    This paper describes measurement of fluid viscosity using a small ball drop device. It requires as little as 100 μl of fluid. Each measurement can be performed in seconds. The experiment is designed to yield reliable viscosity values by operating at properly chosen tilt angles and with calibration using well-characterized Newtonian fluids such as mixtures of glycerol and water. It also yields dynamical viscosity of non-Newtonian fluids at moderate shear rates. The device is easy to assemble and it allows for the measurement of viscosity even when the fluid samples are too small to measure using most commercial viscometers or rheometers. Therefore, the technique is particularly useful in characterizing biological fluids such as solutions of proteins, DNA, and polymers frequently used in biomaterial applications.

  9. Viscosity of fluid nitrogen to pressures of 10 GPa.

    PubMed

    Abramson, Evan H

    2014-10-01

    Shear viscosities of supercritical nitrogen have been measured in the high-pressure diamond-anvil cell, to 673 K and pressures in excess of 10 GPa, using a rolling-sphere technique. The entire set of data, along with lower pressure data from the literature, can be fit to a two-parameter expression in reduced viscosity and reduced residual entropy. The fit spans densities from the dilute gas to 5x the critical density, and two orders magnitude in temperature and in viscosity, with a maximum deviation of 20%. Reduced viscosities scale as ρ(4)/T and comport with the theory of state "isomorphs" for "Roskilde-simple" systems. The new data allow direct comparison with results of molecular dynamic simulations at high densities. PMID:25215593

  10. Crystallization And Viscosity Of Heavy Metal Fluoride Glasses

    NASA Astrophysics Data System (ADS)

    Moynihan, C. T.; Mossadegh, R.; Crichton, S. N.; Gupta, P. K.; Drexhage, M. G.

    1986-05-01

    Shear viscosity data for a glassforming ZrF4-BaF2-LaF3-A1F3 composition covering the range from the highly fluid melt down to the glass transition (10-1 to 1013 P) have been collected from five sources. The viscosity temperature dependence is highly non-Arrhenius and cannot be described by three parameter expressions such as the Fulcher equation. The four parameter Cohen-Grest equation, however, does give a good fit to the data, possibly allowing interpolation in the range of intermediate viscosity important for fiber drawing where data is currently lacking. The viscosity data are compared with crystallization temperatures obtained by DSC during heating and cooling at 10K/min.

  11. Textured-surface quartz resonator fluid density and viscosity monitor

    DOEpatents

    Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.

    1998-08-25

    A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

  12. Viscosity and density of some lower alkyl chlorides and bromides

    SciTech Connect

    Rutherford, W.M.

    1988-07-01

    A high-pressure capillary viscometer, used previously to measure the viscosity of methyl chloride was rebuilt to eliminate the first-order dependence of the measured viscosity on the value assumed for the density of the fluid being investigated. At the same time, the system was arranged so that part of the apparatus could be used to measure density by a volumetric displacement technique. Viscosity and density were measured for ethyl chloride, 1-chloropropane, 1-chlorobutane, methyl bromide, ethyl bromide, and 1-bromopropane. The temperature and pressure ranges of the experiments were 20-150 /sup 0/C and 0.27-6.99 MPa, respectively. The accuracy of the viscosity measurements was estimated to be +-1% and of the density measurements, +-0.2%.

  13. The viscosity of colloidal spheres in deionized suspensions

    NASA Astrophysics Data System (ADS)

    Okubo, Tsuneo

    1987-12-01

    Viscosities of colloidal spheres, i.e., colloidal silica (diameter 8 and 45 nm) and monodisperse polystyrene latices (diameter 85 to 780 nm), are measured in deionized (``salt-free'') suspensions and in the presence of a small amount of NaCl. The reduced viscosities (specific viscosity divided by concentration) of deionized silica (diameter 8 nm) are much higher than would be expected by Einstein's prediction and decrease sharply with increasing concentration. A sharp peak is observed in the reduced viscosity vs concentration curves of deionized colloidal silica of 45 nm diameter and the deionized latex spheres. The peak corresponds to the transition between ``liquid-like'' and ``crystal-like'' structures. These results show that electrostatic intersphere repulsion and the elongated Debye-screening length around the colloidal spheres are essential to explain the extraordinary properties.

  14. Quetol 651: Not just a low viscosity resin.

    PubMed

    Ellis, E Ann

    2016-01-01

    Quetol 651, a low viscosity epoxy resin, is miscible with alcohols, acetone, and water. It is versatile and can be used as a single epoxide or mixed with other epoxides and anhydrides. The most important characteristic is that the addition of Quetol 651 to a formulation results in a lower viscosity embedding medium and allows for good detection of antigenic activity. Properly formulated and mixed resins containing Quetol 651 have excellent sectioning properties and good beam stability. The decrease in viscosity lends to lower specific gravity of the embedding medium and less interfering electron density between specimen elements resulting in better spatial resolution. New formulations and viscosity data are presented and compared to long used, embedding formulations and the extensive uses of Quetol 651 are reviewed. PMID:26516031

  15. Confinement Effect on the Effective Viscosity of Plasticized Polymer Films

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Peng, D.; Ogata, Y.; Tanaka, K.; Yang, Z.; Fujii, Y.; Yamada, N. L.; Lam, C. H.; Tsui, Ophelia K. C.

    We have measured the effective viscosity of polystyrene films with a small (4 wt%) added amount of dioctyl phthalate (DOP) deposited on silica. A broad range of molecular weights, Mw, from 13.7 to 2,100 kg/mol was investigated. Our result shows that for the thin films with Mw <~100 kg/mol, the addition of DOP causes the effective viscosity to decrease by a factor of ~4, independent of Mw. But for the higher Mw films, the effective viscosity of the DOP added films creeps towards that of the neat films with increasing Mw. A model assuming the effective viscosity to be dominated by enhanced surface mobility for the lower Mw films, but surface-promoted interfacial slippage for the higher Mw films is able to account for the experimental observations. We are grateful to the support of National Science Foundation through the project DMR-1310536.

  16. Understanding the Viscosity of Liquids used in Infant Dysphagia Management.

    PubMed

    Frazier, Jacqueline; Chestnut, Amanda H; Jackson, Arwen; Barbon, Carly E A; Steele, Catriona M; Pickler, Laura

    2016-10-01

    When assessing swallowing in infants, it is critical to have confidence that the liquids presented during the swallow study closely replicate the viscosity of liquids in the infant's typical diet. However, we lack research on rheological properties of frequently used infant formulas or breastmilk, and various forms of barium contrast media used in swallow studies. The aim of the current study was to provide objective viscosity measurements for typical infant liquid diet options and barium contrast media. A TA-Instruments AR2000 Advanced Rheometer was used to measure the viscosity of five standard infant formulas, three barium products, and two breastmilk samples. Additionally, this study measured the viscosity of infant formulas and breastmilk when mixed with powdered barium contrast in a 20 % weight-to-volume (w/v) concentration. The study findings determined that standard infant formulas and the two breastmilk samples had low viscosities, at the lower end of the National Dysphagia Diet (NDD) thin liquid range. Two specialty formulas tested had much thicker viscosities, close to the lower boundary of the NDD nectar-thick liquid range. The study showed differences in viscosity between 60 % w/v barium products (Liquid E-Z-Paque(®) and E-Z-Paque(®) powder); the powdered product had a much lower viscosity, despite identical barium concentration. When E-Z-Paque(®) powdered barium was mixed in a 20 % w/v concentration using water, standard infant formulas, or breastmilk, the resulting viscosities were at the lower end of the NDD thin range and only slightly thicker than the non-barium comparator liquids. When E-Z-Paque(®) powdered barium was mixed in a 20 % w/v concentration with the two thicker specialty formulas (Enfamil AR 20 and 24 kcal), unexpected alterations in their original viscosity occurred. These findings highlight the clinical importance of objective measures of viscosity as well as objective data on how infant formulas or breastmilk may change in

  17. Viscosity of α-pinene secondary organic material and implications for particle growth and reactivity.

    PubMed

    Renbaum-Wolff, Lindsay; Grayson, James W; Bateman, Adam P; Kuwata, Mikinori; Sellier, Mathieu; Murray, Benjamin J; Shilling, John E; Martin, Scot T; Bertram, Allan K

    2013-05-14

    Particles composed of secondary organic material (SOM) are abundant in the lower troposphere. The viscosity of these particles is a fundamental property that is presently poorly quantified yet required for accurate modeling of their formation, growth, evaporation, and environmental impacts. Using two unique techniques, namely a "bead-mobility" technique and a "poke-flow" technique, in conjunction with simulations of fluid flow, the viscosity of the water-soluble component of SOM produced by α-pinene ozonolysis is quantified for 20- to 50-μm particles at 293-295 K. The viscosity is comparable to that of honey at 90% relative humidity (RH), similar to that of peanut butter at 70% RH, and at least as viscous as bitumen at ≤30% RH, implying that the studied SOM ranges from liquid to semisolid or solid across the range of atmospheric RH. These data combined with simple calculations or previous modeling studies are used to show the following: (i) the growth of SOM by the exchange of organic molecules between gas and particle may be confined to the surface region of the particles for RH ≤ 30%; (ii) at ≤30% RH, the particle-mass concentrations of semivolatile and low-volatility organic compounds may be overpredicted by an order of magnitude if instantaneous equilibrium partitioning is assumed in the bulk of SOM particles; and (iii) the diffusivity of semireactive atmospheric oxidants such as ozone may decrease by two to five orders of magnitude for a drop in RH from 90% to 30%. These findings have possible consequences for predictions of air quality, visibility, and climate. PMID:23620520

  18. Viscosity of α-pinene secondary organic material and implications for particle growth and reactivity

    PubMed Central

    Renbaum-Wolff, Lindsay; Grayson, James W.; Bateman, Adam P.; Kuwata, Mikinori; Sellier, Mathieu; Murray, Benjamin J.; Shilling, John E.; Martin, Scot T.; Bertram, Allan K.

    2013-01-01

    Particles composed of secondary organic material (SOM) are abundant in the lower troposphere. The viscosity of these particles is a fundamental property that is presently poorly quantified yet required for accurate modeling of their formation, growth, evaporation, and environmental impacts. Using two unique techniques, namely a “bead-mobility” technique and a “poke-flow” technique, in conjunction with simulations of fluid flow, the viscosity of the water-soluble component of SOM produced by α-pinene ozonolysis is quantified for 20- to 50-μm particles at 293–295 K. The viscosity is comparable to that of honey at 90% relative humidity (RH), similar to that of peanut butter at 70% RH, and at least as viscous as bitumen at ≤30% RH, implying that the studied SOM ranges from liquid to semisolid or solid across the range of atmospheric RH. These data combined with simple calculations or previous modeling studies are used to show the following: (i) the growth of SOM by the exchange of organic molecules between gas and particle may be confined to the surface region of the particles for RH ≤ 30%; (ii) at ≤30% RH, the particle-mass concentrations of semivolatile and low-volatility organic compounds may be overpredicted by an order of magnitude if instantaneous equilibrium partitioning is assumed in the bulk of SOM particles; and (iii) the diffusivity of semireactive atmospheric oxidants such as ozone may decrease by two to five orders of magnitude for a drop in RH from 90% to 30%. These findings have possible consequences for predictions of air quality, visibility, and climate. PMID:23620520

  19. Fatty acids, membrane viscosity, serotonin and ischemic heart disease

    PubMed Central

    2010-01-01

    Novel markers for ischemic heart disease are under investigation by the scientific community at international level. This work focuses on a specific platelet membrane fatty acid condition of viscosity which is linked to molecular aspects such as serotonin and G proteins, factors involved in vascular biology. A suggestive hypothesis is considered about the possibility to use platelet membrane viscosity, in relation to serotonin or, indirectly, the fatty acid profile, as indicator of ischemic risk. PMID:20825633

  20. Measurement of viscosity, density and gas solubility of refrigerant blends

    SciTech Connect

    Cavestri, R.C.; Munk, J. )

    1993-04-01

    Liquid/liquid miscibilities of four different 32 ISO VG polyolesters and one alkylbenzene at three concentrations were determined. Also a full vapor lubricant equilibrium (VLE) viscosity reduction of a 32 ISO VG mineral oil with HCFC-22 is complete. Partial viscosity reduction information by the fractionate components from R-502 in 32 ISO VG mineral oil is presented from 40C (104C) and 70C (158F) isotherms.

  1. Viscosity and mutual diffusion in strongly asymmetric plasma mixtures

    SciTech Connect

    Bastea, S

    2004-09-07

    The authors present molecular dynamics simulation results for the viscosity and mutual diffusion constant of a strongly asymmetric two-component plasma (TCP). They compare the results with available theoretical models previously tested for much smaller asymmetries. for the case of viscosity they propose a new predictive framework based on the linear mixing rule, while for mutual diffusion they point out some consistency problems of widely used Boltzmann equation based models.

  2. Influence of viscosity and the adiabatic index on planetary migration

    NASA Astrophysics Data System (ADS)

    Bitsch, B.; Boley, A.; Kley, W.

    2013-02-01

    Context. The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state. It has been shown that in active disks, where the internal dissipation is balanced by radiative transport, migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. Aims: In this paper we investigate the influence of different viscosity prescriptions (α-type and constant) and adiabatic indices on disk structures. We then determine how this affects the migration rate of planets embedded in such disks. Methods: We perform three-dimensional numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20 MEarth planets is studied. Results: Low-viscosity disks have cooler temperatures and the migration rates of embedded planets tend toward the isothermal limit. Hence, in these disks, planets migrate inwards even in the fully radiative case. The effect of outward migration can only be sustained if the viscosity in the disk is large. Overall, the differences between the treatments for the equation of state seem to play a more important role in disks with higher viscosity. A change in the adiabatic index and in the viscosity changes the zero-torque radius that separates inward from outward migration. Conclusions: For larger viscosities, temperatures in the disk become higher and the zero-torque radius moves to larger radii, allowing outward migration of a 20-MEarth planet to persist over an extended radial range. In combination with large disk masses, this may allow for an extended period of the outward migration of growing

  3. Cytokine modulation of human blood viscosity from vivax malaria patients.

    PubMed

    Scherer, Edson Fredulin; Cantarini, Déborah Giovanna; Siqueira, Renan; Ribeiro, Elton Brito; Braga, Érika Martins; Honório-França, Adenilda Cristina; França, Eduardo Luzía

    2016-06-01

    Malaria is a major infectious disease in several countries and is caused by protozoa of the genus Plasmodium. In vivax malaria patients, inflammatory processes occur, as well as changes in cytokines and blood flow. The present study analyzed the cytokine modulation of blood viscosity from patients infected with Plasmodium vivax (P. vivax). Blood samples were collected from 42 non-infected individuals (control group) and 37 individuals infected with P. vivax. The IL-2, IL-4, IL-6, IL-10, TNFα, TGF-β and IL-17 cytokine concentrations in the serum were assessed, and the blood rheological properties were determined. The analysis of blood viscosity for shear rates revealed that the blood viscosity of the infected patients was significantly greater than that of the non-infected individuals. The viscosity of the blood was greater in the infected individuals than in the non-infected subjects. The serum from individuals with P. vivax infections exhibited higher IFN-γ and IL-17 concentrations and lower TGF-β levels. Incubation of the blood from infected individuals with IL-17 or IL-17 associated with IFN-γ reduced the viscosity to rates equivalent to the blood from non-infected individuals. Independently of cytokine modulation, no correlation was found between the parasitemia and blood viscosity of the infected patients. These data suggest that the alterations of blood viscosity are relevant as an auxiliary tool for the clinical diagnosis of disease. In malaria, erythrocytes are more sensitive to osmotic shock, and the reduction of viscosity by IL-17 may be related to a possible immunomodulator agent during infection. PMID:26948901

  4. Viscosities of solutions of interest for studies of absorption processes

    SciTech Connect

    Una, G.V.; Romero, F.C.; Dacosta, E.A.; Martinez, R.M.; Calvo, P.P. . Chemical Engineering Dept.)

    1994-01-01

    The authors report the viscosities of solution of glycerin, sucrose, glucose, or fructose in water or in 0.5 M sodium carbonate + 0.5 M sodium bicarbonate buffer at concentrations from 0 to 150g and temperatures from 288.1 to 323.1 K. An equation gave the dependence of kinematic viscosity in concentration and temperature with a deviation of less than 1.2%.

  5. Dynamics of rising bubble inside a viscosity-stratified medium

    NASA Astrophysics Data System (ADS)

    Premlata, A. R.; Tripathi, Manoj Kumar; Sahu, Kirti Chandra

    2015-07-01

    The rising bubble dynamics in an unconfined quiescent viscosity-stratified medium has been numerically investigated. This is frequently encountered in industrial as well as natural phenomena. In spite of the large number of studies carried out on bubbles and drops, very few studies have examined the influence of viscosity stratification on bubble rise dynamics. To the best of our knowledge, none of them have isolated the effects of viscosity-stratification alone, even though it is known to influence the dynamics extensively, which is the main objective of the present study. By conducting time-dependent simulations, we present a library of bubble shapes in the Galilei and the Eötvös numbers plane. Our results demonstrate some counter-intuitive phenomena for certain range of parameters due to the presence of viscosity stratification in the surrounding fluid. We found that in a linearly increasing viscosity medium, for certain values of parameters, bubble undergoes large deformation by forming an elongated skirt, while the skirt tends to physically separate the wake region from the rest of the surrounding fluid. This peculiar dynamics is attributed to the migration of less viscous fluid that is carried in the wake of the bubble as it rises, and thereby creating an increasingly larger viscosity contrast between the fluid occupied in the wake region and the surrounding fluid, unlike that observed in a constant viscosity medium. It is also observed that the effect of viscosity stratification is qualitatively different for different regimes of the dimensionless parameters. In future, it will be interesting to investigate this problem in three-dimensions.

  6. Preparation of high-viscosity, partially hydrolyzed polymethacrylamides

    SciTech Connect

    Shepitka, J.S.; Case, C.E.; Donaruma, L.G.; Hatch, M.J.; Kilmer, N.H.; Khune, G.D.; Martin, F.D.; Ward, J.S.; Wilson, K.V.

    1983-12-01

    Due to the high chain transfer to monomer, the homopolymerization of methacrylamide yields polymers of extremely low molecular weight. On partial alkaline hydrolysis, the viscosities of these polymers in aqueous solution are much inferior to those of partially hydrolyzed polyacrylamide (HPAM). However, polymethacrylamides prepared by room temperature, persulfate-initiated polymerization in the presence of small amounts of N,N'-methylenebisacrylamide demonstrate posthydrolysis reduced viscosities in 0.01% NaCl comparable to typical commercial HPAM materials.

  7. High sperm chromatin stability in semen with high viscosity.

    PubMed

    Gonzales, G F; Sánchez, A

    1994-01-01

    This study was designed to determine the effects of high semen viscosity on sperm chromatin stability. Semen samples obtained from men with normal and high viscosity were studied. Sperm chromatin stability was tested by exposure to sodium dodecyl sulfate (SDS) only and SDS together with a zinc-chelating agent, disodium ethylene diamine tetraacetate (SDS+EDTA). After SDS incubation, stable sperm was 61.36 +/- 3.0 and 54.71 +/- 3.42% for normal and high semen viscosity, respectively (P:NS), and after SDS+EDTA, it was further reduced to 12.48 +/- 0.99% in semen samples with normal consistency and in a less magnitude in semen samples with high viscosity (25.6 +/- 5.2). Comparing values obtained in SDS+EDTA, a high sperm stability was observed in samples with hyperviscosity (p < .02). In samples with normal viscosity the percentage of grossly swollen sperm increased 5.40 times from the values obtained in sperm incubated with SDS to the values obtained with SDS+EDTA, whereas in samples with high viscosity the percentage increased only 2.2 times. It is concluded that hyperviscosity is associated with a high sperm chromatin stability in situations when a zinc-chelating agent is present. PMID:8122934

  8. Viscosities of aluminum-rich Al-Cu liquid alloys

    NASA Astrophysics Data System (ADS)

    Ganesan, S.; Speiser, R.; Poirier, D. R.

    1987-06-01

    Viscosity data for Al-Cu liquid alloys in the ranges of 0≤ C L≤33.1 wt pct Cu and 1173≤ T ≤973 K are reviewed. It was found that Andrade's equation can be used to represent the variation of viscosity with temperature for a given composition, but that each of the two parameters in Andrade's equation shows no systematic variation with composition of the liquid-alloys. Consequently, arithmetic averages of the parameters were used and assumed to apply to all compositions in the range 0≤ C L ≤33.1 wt pct Cu. Such a procedure implies that the viscosity happens to vary with composition solely because the specific volume varies with composition. In order to establish the predictability of extrapolating such simple behavior, a more complex model was considered. The latter model was recently presented by Kucharski and relates viscosity to the structure and thermodynamics of liquid alloys. Viscosities obtained by interpolating Andrade's equation and Kucharski's model compare closely; furthermore, values obtained by extrapolations to lower temperatures also compare favorably. Finally the simpler model was used to calculate the viscosity of the interdendritic liquid during solidification.

  9. Viscosity of alumina nanoparticles dispersed in car engine coolant

    SciTech Connect

    Kole, Madhusree; Dey, T.K.

    2010-09-15

    The present paper, describes our experimental results on the viscosity of the nanofluid prepared by dispersing alumina nanoparticles (<50 nm) in commercial car coolant. The nanofluid prepared with calculated amount of oleic acid (surfactant) was tested to be stable for more than 80 days. The viscosity of the nanofluids is measured both as a function of alumina volume fraction and temperature between 10 and 50 C. While the pure base fluid display Newtonian behavior over the measured temperature, it transforms to a non-Newtonian fluid with addition of a small amount of alumina nanoparticles. Our results show that viscosity of the nanofluid increases with increasing nanoparticle concentration and decreases with increase in temperature. Most of the frequently used classical models severely under predict the measured viscosity. Volume fraction dependence of the nanofluid viscosity, however, is predicted fairly well on the basis of a recently reported theoretical model for nanofluids that takes into account the effect of Brownian motion of nanoparticles in the nanofluid. The temperature dependence of the viscosity of engine coolant based alumina nanofluids obeys the empirical correlation of the type: log ({mu}{sub nf}) = A exp(BT), proposed earlier by Namburu et al. (author)

  10. Viscosity of liquid fayalite up to 9 GPa

    NASA Astrophysics Data System (ADS)

    Spice, Holly; Sanloup, Chrystèle; Cochain, Benjamin; de Grouchy, Charlotte; Kono, Yoshio

    2015-01-01

    The viscosity of liquid fayalite (Fe2SiO4) was determined up to 9.2 GPa and 1850 °C using in situ falling sphere viscometry and X-ray radiography imaging. The viscosity of liquid fayalite was found to decrease both along the melting curve and an isotherm, therefore temperature is thought to have little effect on liquid fayalite viscosity at high pressure. The results are in contrast with previous studies on depolymerised silicate melts which found viscosity to increase with pressure. In accordance with recent in situ structural measurements on liquid fayalite, the viscosity decrease is likely a result of the increase in Fe-O coordination with pressure. The results show that liquid silicate viscosities need to be considered on an individual basis and can be strongly dependent on the melt structure and composition. This has important implications for models of planetary differentiation. In particular, terrestrial bodies with high Fe contents and reducing mantle conditions are likely to have had very mobile melts at depth.

  11. Effect of Viscosity on the Crystallization of Undercooled Liquids

    NASA Technical Reports Server (NTRS)

    2003-01-01

    There have been numerous studies of glasses indicating that low-gravity processing enhances glass formation. NASA PI s are investigating the effect of low-g processing on the nucleation and crystal growth rates. Dr. Ethridge is investigating a potential mechanism for glass crystallization involving shear thinning of liquids in 1-g. For shear thinning liquids, low-g (low convection) processing will enhance glass formation. The study of the viscosity of glass forming substances at low shear rates is important to understand these new crystallization mechanisms. The temperature dependence of the viscosity of undercooled liquids is also very important for NASA s containerless processing studies. In general, the viscosity of undercooled liquids is not known, yet knowledge of viscosity is required for crystallization calculations. Many researchers have used the Turnbull equation in error. Subsequent nucleation and crystallization calculations can be in error by many orders of magnitude. This demonstrates the requirement for better methods for interpolating and extrapolating the viscosity of undercooled liquids. This is also true for undercooled water. Since amorphous water ice is the predominant form of water in the universe, astrophysicists have modeled the crystallization of amorphous water ice with viscosity relations that may be in error by five orders-of-magnitude.

  12. A Structurally Based Viscosity Model for Oxide Melts

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Hua; Chou, Kuo-Chih; Mills, Ken

    2014-04-01

    A structurally based viscosity model is proposed to represent the viscosity of oxide melts as functions of both temperature and composition; The oxide melts cover the following constituents: Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, FeO, MnO, Al2O3, SiO2, CaF2, TiO2, Fe2O3, and P2O5. The model describes the slag structure in terms of the various forms of oxygen ions which are classified according to the metal cations they bond with. Approximate methods for calculating the concentrations of these oxygen ions are proposed and are then used to describe the effect of melt structure on viscosity. The model provides a good description of the variations in viscosity with composition and temperature. The measured viscosities were compared with values calculated with the model, and the current model was found to provide reliable estimates of viscosities of slags used in various industrial processes ( e.g., blast furnace, basic oxygen steelmaking, ladle refining, continuous casting of steel, coal gasification, and electroslag remelting).

  13. An Improved Comprehensive Model for the Apparent Viscosity of Blood

    NASA Astrophysics Data System (ADS)

    Jacobitz, Frank; Anderson, Spencer

    2008-11-01

    An improved comprehensive model for the apparent viscosity of blood is developed and used in simulations of the microcirculation in capillary bundles of rat spinotrapezius muscle fascia. In the microcirculation, the apparent viscosity of blood depends on the local vessel diameter, hematocrit, and shear rate. The proposed comprehensive model extends the apparent viscosity model developed by Pries, Secomb, Gaehtgens, and Gross (Circulation Research, 67, 826-834, 1990), which describes the effect of vessel diameter and hematocrit on the apparent viscosity. A shear thinning term is developed using the experimental data of Lipowsky, Usami, and Chien (Microvascular Research, 19, 297-319, 1980). Curve fits of this data can be combined with equations given in the Pries et al. work to create a system of equations that can be used to find the shear thinning factor. The simulations based on the improved apparent viscosity model use realistic vessel topology for the microvasculature, reconstructed from microscope images of tissue samples, and consider passive and active vessel properties. The numerical method is based on a Hagen-Poiseuille balance in the microvessels and a sparse matrix solver is used to obtain the solution. It was found that the inclusion of the shear factor decreases the overall flowrate in the capillary bundle. Many vessel connections in the fascia are characterized by relatively low shear rates and therefore increased apparent viscosity.

  14. CSI: Hard Drive

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2008-01-01

    Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

  15. DrivePy

    Energy Science and Technology Software Center (ESTSC)

    2014-08-30

    DrivePy is physics-based drivetrain model that sizes drivetrain components based on aerodynamic and operational loads for use in a systems engineering model. It also calculates costs based on empirical data collected by NREL's National Wind Technology Center.

  16. No Pass, No Drive?

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2001-01-01

    Discusses basis for Kentucky appellate court decision that state's no-pass, no-drive statute did not violate due-process and equal-protection clauses of the Kentucky and federal constitutions, but did violate the federal Family Education Rights and Privacy Act, but nevertheless did not invalidate the statute. Explains why the decision is…

  17. Teachers with Drive

    ERIC Educational Resources Information Center

    Coggins, Celine; Diffenbaugh, P. K.

    2013-01-01

    For students in U.S. classrooms today, the odds of being assigned to an inexperienced teacher are higher than they have ever been because so many teachers, some in the top 20 percent of effectiveness are leaving the classroom in their first five years. Coggins and Diffenbaugh turn to Daniel Pink's work on drive to determine how to motivate…

  18. [Epilepsy and driving].

    PubMed

    Adam, Claude

    2015-10-01

    Epilepsy contributes little to road traffic accidents (0.25% of accidents) compared, for instance, to alcohol abuse (at least 30 times higher). Current factors, such as age and sex, or other chronic medical conditions also increase the risk of road traffic accidents but do not carry driving restrictions. So, the European Commission fairly established rules permitting individuals having experienced one or more epileptic seizures to drive if their road accident risk is low. Road accident risk related to epileptic seizures in various clinical situations is evaluated by the driving license commission, mainly with the aid of criteria based on seizure-free periods. A person who has had an epileptic seizure should notify the authorities. He should be advised by treating physician not to drive before. In case of an authorisation, any new relevant event should be notified to the authorities in the course of legal follow-up. Improvements of the current regulations by European data registries are under way. PMID:26482490

  19. COMMENT: No warp drive

    NASA Astrophysics Data System (ADS)

    Coule, D. H.

    1998-08-01

    The warp drive spacetime of Alcubierre is impossible to set up without first being able to distribute matter at tachyonic speed, put roughly, you need one to make one! However, over small distances, where the energy conditions possibly can be violated, one can envision opening the light-cones to increase the apparent speed of light.

  20. Drive-Through Training

    ERIC Educational Resources Information Center

    Carter, Margie

    2010-01-01

    In this article, the author discusses how the early childhood field's approach to staff training reflects the drive-through, fast-food culture. Year after year directors send their teachers to workshops to get some quick refresher techniques. The author suggests that rather than focusing professional development on topics, focus on observing…

  1. Driving skills after whiplash.

    PubMed

    Gimse, R; Bjørgen, I A; Straume, A

    1997-09-01

    Previous studies have shown that some persons with longlasting problems after whiplash have changed eye movements. These changes have been related to disturbance of the posture control system. The question raised in the present study is whether such disturbances can influence daily life functions connected with balance, position and external movements, such as car driving. A group of 23 persons with disturbed eye movements due to whiplash injury, was tested in a driving simulator, together with a closely matched control group. The results revealed significant differences between the two groups with respect to response times to the traffic signs presented, identification of type of sign, as well as steering precision while the subjects' attention was directed to the process of identifying the signs. Alternative explanations such as driving experience, pain, medication or malingering are at least partly controlled for, but cannot completely be ruled out. A distorted posture control system leading to disturbance of eye movements seems to be the most likely primary causative factor, but these disturbances are most certainly complexly determined. Reduced attention capacity is considered to be a mediating secondary factor. Registration of eye movements may be a useful diagnostic tool to evaluate driving skill after whiplash. PMID:9309948

  2. Driving While Intoxicated.

    ERIC Educational Resources Information Center

    Brick, John

    Alcohol intoxication increases the risk of highway accidents, the relative risk of crash probability increasing as a function of blood alcohol content (BAC). Because alcohol use is more prevalent than use of other drugs, more is known about the relationship between alcohol use and driving. Most states presume a BAC of .10% to be evidence of drunk…

  3. Effects of media viscosity and particle size on optical trapping of microspheres

    NASA Astrophysics Data System (ADS)

    Khatibzadeh, Nima; Rocha, Yesenia; Shi, Linda Z.; Berns, Michael W.

    2014-03-01

    In this study, we investigated the effects of size and surrounding media viscosity on trapping of microspheres. A continuous wave ytterbium fiber laser with a 1064 nm wavelength was used to create an optical tweezers system for optical manipulation experiments. Briefly, the system consisted of an inverted microscope, and a 100X 1.4 NA oil immersion objective through which the laser beam converged to form the optical trap. The laser beam was collimated, steered, and coupled to the microscope through the epifluorescence microscope port. The laser power at the trap focal spot was determined by measuring the input power at the back aperture of the objective multiplied by the objective transmission factor at 1064 nm measured by a modified dual objective method. Polystyrene microspheres varying in diameter from 5 to 15 microns were suspended in liquid media in glass bottom petri dishes prior to trapping experiments. The microspheres were trapped at different trapping powers, and fluidic viscous drag forces where applied to the optically trapped microspheres by driving a computer controlled 2D motorized microscope stage at known velocities. The drag forces were calculated at the point that the microspheres fell out of the trap, based on the Stokes equation for flow around spheres. The data show a linear relationship between trapping force and trap power within the range of the microsphere diameters and media viscosity values used. The work includes calculation of the dimensionless trap efficiency coefficient (Q) at 1064 nm wavelength and the corresponding effects of media viscosity and microsphere size on (Q).

  4. High Resolution Magnetotail Simulations of Bursty Bulk Flows

    NASA Astrophysics Data System (ADS)

    Buzulukova, N.; Dorelli, J.; Glocer, A.; Fok, M. C. H.; Toth, G.

    2014-12-01

    We present the results of high resolution resistive MHD simulations of bursty bulk flows using the BATSRUS magnetosphere model. We performed a number of runs with three levels of constant resistivity. For each resistivity level, we studied the dependence on tail resolution and looked for solutions where numerical resistivity was small compared to the set physical resistivity. For constant solar wind driving (southward Bz IMF), we found the formation of bursty bulk flows (BBFs) and dipolarization fronts when the resistivity was below a critical value. We extracted virtual s/c data through dipolarization fronts and BBFs and compared with observed properties of BBFs. We also studied the ionospheric response to BBF formation. By switching on/off the ring current module (CRCM) in the BATSRUS, we examined relationship between BBFs and ring current injections.

  5. Linking structure to fragility in bulk metallic glass-forming liquids

    SciTech Connect

    Wei, Shuai E-mail: m.stolpe@mx.uni-saarland.de; Stolpe, Moritz E-mail: m.stolpe@mx.uni-saarland.de; Gross, Oliver; Gallino, Isabella; Hembree, William; Busch, Ralf; Evenson, Zach; Bednarcik, Jozef; Kruzic, Jamie J.

    2015-05-04

    Using in-situ synchrotron X-ray scattering, we show that the structural evolution of various bulk metallic glass-forming liquids can be quantitatively connected to their viscosity behavior in the supercooled liquid near T{sub g}. The structural signature of fragility is identified as the temperature dependence of local dilatation on distinct key atomic length scales. A more fragile behavior results from a more pronounced thermally induced dilatation of the structure on a length scale of about 3 to 4 atomic diameters, coupled with shallower temperature dependence of structural changes in the nearest neighbor environment. These findings shed light on the structural origin of viscous slowdown during undercooling of bulk metallic glass-forming liquids and demonstrate the promise of predicting the properties of bulk metallic glasses from the atomic scale structure.

  6. Does the magnetic field of a multipole stator winding drive flow of a ferrofluid in a cylindrical container?

    NASA Astrophysics Data System (ADS)

    Torres-Díaz, Isaac; Rinaldi, Carlos

    The flow of a ferrofluid in a stationary cylindrical container driven by a rotating magnetic field has received considerable attention since the inception of the field of ferrohydrodynamics. Much controversy has resulted regarding the existence, or lack thereof, of bulk flow under conditions of a rotating uniform magnetic field, which can be generated for example, using a two-pole stator winding. The original observations of flow at the interface showed counter-rotation of field and fluid, whereas recent observations of bulk flow using the ultrasound technique have shown co-rotation of field and fluid. Various theories have been advanced over the years to explain the observed phenomena, including the spin diffusion theory of Shliomis and the hypothesis that it is field non-uniformity, generated by non-ideal stator winding distributions, that actually drives the flow, as first proposed by Glazov. We have revisited this problem from an analytical perspective by solving the ferrohydrodynamic and magnetoquasistatic equations self-consistently for the case of ferrofluid in a cylindrical container, with and without an internal co-axial cylinder, and driven by the field generated by a multipole stator winding distribution. In such a winding increasing the number of poles results in increasingly non-uniform fields. It is shown that regardless of the number of poles in the stator winding the ferrohydrodynamic equations do not predict any flow in either geometry as long as the spin viscosity parameter is assumed to be zero. Velocity profiles are obtained for both geometries and arbitrary number of poles for the case of non-zero spin viscosity. It is shown that only for the case of a two-pole stator winding and ferrofluid constrained to the annular space between an inner and outer cylinder do the ferrohydrodynamic equations predict co-rotation of fluid and field close to the outer cylinder and counter-rotation of fluid and field close to the inner cylinder, in qualitative

  7. Longitudinal bulk acoustic mass sensor

    SciTech Connect

    Hales, J. H.; Teva, J.; Boisen, A.; Davis, Z. J.

    2009-07-20

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10{sup -15} g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise in the currently applied measurement system allows for a minimum detectable mass of 0.5 fg in air.

  8. Development of Viscosity Model for Petroleum Industry Applications

    NASA Astrophysics Data System (ADS)

    Motahhari, Hamed reza

    Heavy oil and bitumen are challenging to produce and process due to their very high viscosity, but their viscosity can be reduced either by heating or dilution with a solvent. Given the key role of viscosity, an accurate viscosity model suitable for use with reservoir and process simulators is essential. While there are several viscosity models for natural gases and conventional oils, a compositional model applicable to heavy petroleum and diluents is lacking. The objective of this thesis is to develop a general compositional viscosity model that is applicable to natural gas mixtures, conventional crudes oils, heavy petroleum fluids, and their mixtures with solvents and other crudes. The recently developed Expanded Fluid (EF) viscosity correlation was selected as a suitable compositional viscosity model for petroleum applications. The correlation relates the viscosity of the fluid to its density over a broad range of pressures and temperatures. The other inputs are pressure and the dilute gas viscosity. Each fluid is characterized for the correlation by a set of fluid-specific parameters which are tuned to fit data. First, the applicability of the EF correlation was extended to asymmetric mixtures and liquid mixtures containing dissolved gas components. A new set of mass-fraction based mixing rules was developed to calculate the fluid-specific parameters for mixtures. The EF correlation with the new set of mixing rules predicted the viscosity of over 100 mixtures of hydrocarbon compounds and carbon dioxide with overall average absolute relative deviations (AARD) of less than 10% either with measured densities or densities estimated by Advanced Peng-Robinson equation of state (APR EoS). To improve the viscosity predictions with APR EoS-estimated densities, general correlations were developed for non-zero viscosity binary interaction parameters. The EF correlation was extended to non-hydrocarbon compounds typically encountered in natural gas industry. It was

  9. Shear viscosity for a heated granular binary mixture at low density.

    PubMed

    Montanero, José María; Garzó, Vicente

    2003-02-01

    The shear viscosity for a heated granular binary mixture of smooth hard spheres at low density is analyzed. The mixture is heated by the action of an external driving force (Gaussian thermostat) that exactly compensates for cooling effects associated with the dissipation of collisions. The study is made from the Boltzmann kinetic theory, which is solved by using two complementary approaches. First, a normal solution of the Boltzmann equation via the Chapman-Enskog method is obtained up to first order in the spatial gradients. The mass, heat, and momentum fluxes are determined and the corresponding transport coefficients identified. As in the free cooling case [V. Garzó and J. W. Dufty, Phys. Fluids 14, 1476 (2002)], practical evaluation requires a Sonine polynomial approximation, and here it is mainly illustrated in the case of the shear viscosity. Second, to check the accuracy of the Chapman-Enskog results, the Boltzmann equation is numerically solved by means of the direct simulation Monte Carlo method. The simulation is performed for a system under uniform shear flow, using the Gaussian thermostat to control inelastic cooling. The comparison shows an excellent agreement between theory and simulation over a wide range of values of the restitution coefficients and the parameters of the mixture (masses, concentrations, and sizes). PMID:12636672

  10. High-Temperature Liquid Metal Infusion Considering Surface Tension-Viscosity Dissipation

    NASA Astrophysics Data System (ADS)

    Kumar, Vinod; Harris, Christopher K.; Bronson, Arturo; Shantha-Kumar, Sanjay; Medina, Arturo

    2016-02-01

    In considering the significant effect of the surface tension-viscosity dissipation driving the fluid flow within a capillary, high-temperature liquid metal infusion was analyzed for titanium, yttrium, hafnium, and zirconium penetrating into a packed bed. A model of the dissipation considers the momentum balance within the capillary to determine the rate of infusion, which is compared with the Semlak-Rhines model developed for liquid metal penetration into a packed bed assumed as a bundle of tubes mimicking the porosity of a packed bed. For liquid Ti, the penetration rate was calculated from 0.2 µs to 1 ms and rose to a maximum of 7 m/s at approximately 1 µs; after which, the rate decreased to 0.7 m/s at 1 ms. Beyond 10 µs, the decreasing trend of the rate of penetration determined by the model of dissipation compared favorably with the Semlak-Rhines equation.

  11. Viscosity Relaxation in Molten HgZnTe

    NASA Technical Reports Server (NTRS)

    Baird, James K.

    2002-01-01

    Because of its narrow electronic band-gap, HgZnTe solid solutions have been proposed as effective detectors for infrared radiation. To produce the best single crystals of these materials for this application, knowledge of the phase diagram that governs the freezing of the liquid is essential. Besides the phase diagram, however, some information concerning the thermophysical properties of the melt, such as viscosity, density, specific heat, and enthalpy of mixing, can also be useful. Of these thermophysical properties, the viscosity is perhaps of the most interest scientifically. Measurements using the oscillating cup method have shown that the isothermal melt requires tens of hours of equilibration time before a steady value of the viscosity can be achieved. Over this equilibration time, which depends upon temperature, the viscosity can increase by as much as a factor of two before reaching a steady state. We suggest that this relaxation phenomenon may be due to a slight polymerization of Te atoms in the melt. To account for the time dependence of the viscosity in the HgZnTe melt, we propose that the liquid acts as a solvent that favors the formation of Te atom chains. We suggest that as the melt is cooled from a high temperature to the temperature for measurement of the viscosity, a free radical polymerization of Te atoms begins. To estimate this average molecular weight, we use a simple free radical polymerization mechanism, including a depolymerization step, to calculate the time dependence to the concentration of each Te polymer molecular weight fraction. From these molecular weight fractions, we compute the weight average molecular weight of the distribution. Using the semi-empirical relation between average molecular weight and viscosity, we obtain a formula for the time dependence of the viscosity of the melt. Upon examining this formula, we find that the viscosity achieves a steady value when a balance is achieved between the rate of formation of the chains

  12. Radical Cage Effects: Comparison of Solvent Bulk Viscosity and Microviscosity in Predicting the Recombination Efficiencies of Radical Cage Pairs.

    PubMed

    Barry, Justin T; Berg, Daniel J; Tyler, David R

    2016-08-01

    This study reports the results of experiments that probed how solvents affect the recombination efficiency (FcP) of geminate radical cage pairs. The macroviscosity of solvents has traditionally been used to make quantitative predictions about FcP, but experiments reported here show that FcP varies dramatically for solvent systems with identical macroviscosities. Experiments show that FcP correlates with the solvent microviscosity: five different solvent systems (consisting of a solvent and a structurally similar viscogen) were examined, and FcP was the same for all five solvent systems at any particular microviscosity. The translational diffusion coefficient of the radicals (measured by DOSY) in the solvent system was used to define the microviscosity of the solvent system. PMID:27430611

  13. Measurement of the Surface Dilatational Viscosity of an Insoluble Surfactant Monolayer at the Air/Water Interface Using a Pendant Drop Apparatus

    NASA Technical Reports Server (NTRS)

    Lorenzo, Jose; Couzis, Alex; Maldarelli, Charles; Singh, Bhim S. (Technical Monitor)

    2000-01-01

    When a fluid interface with surfactants is at rest, the interfacial stress is isotropic (as given by the equilibrium interfacial tension), and is described by the equation of state which relates the surface tension to the surfactant surface concentration. When surfactants are subjected to shear and dilatational flows, flow induced interaction of the surfactants; can create interfacial stresses apart from the equilibrium surface tension. The simplest relationship between surface strain rate and surface stress is the Boussinesq-Scriven constitutive equation completely characterized by three coefficients: equilibrium interfacial tension, surface shear viscosity, and surface dilatational viscosity Equilibrium interfacial tension and surface shear viscosity measurements are very well established. On the other hand, surface dilatational viscosity measurements are difficult because a flow which change the surface area also changes the surfactant surface concentration creating changes in the equilibrium interfacial tension that must be also taken into account. Surface dilatational viscosity measurements of existing techniques differ by five orders of magnitude and use spatially damped surface waves and rapidly expanding bubbles. In this presentation we introduce a new technique for measuring the surface dilatational viscosity by contracting an aqueous pendant drop attached to a needle tip and having and insoluble surfactant monolayer at the air-water interface. The isotropic total tension on the surface consists of the equilibrium surface tension and the tension due to the dilation. Compression rates are undertaken slow enough so that bulk hydrodynamic stresses are small compared to the surface tension force. Under these conditions we show that the total tension is uniform along the surface and that the Young-Laplace equation governs the drop shape with the equilibrium surface tension replaced by the constant surface isotropic stress. We illustrate this technique using

  14. Fabrication of Bulk Glassy Alloy Foams by High Pressure Hydrogen

    NASA Astrophysics Data System (ADS)

    Wada, Takeshi; Inoue, Akihisa

    Porous Pd42.5Cu30Ni7.5P20 bulk glassy alloy rods with porosities of up to 70% were successfully prepared by high pressure hydrogen of 15 MPa. The melt of Pd42.5Cu30Ni7.5P20 alloy kept under high pressure hydrogen absorbs hydrogen and subsequent water quenching of the melt causes the homogeneous dispersion of hydrogen bubbles, which was resulted from the decrease of hydrogen solubility with decrease of pressure. Annealing the hydrogen bubble containing sample at a supercooled liquid state under vacuum, the bubbles are allowed to expand due to the decrease of viscosity of metallic glass matrix. Pores expansion continues until glassy matrix crystallizes or the equilibration among pressure of the pores, pressure of the atmosphere and surface tension is achieved. By utilizing these phenomena, pores up to 80 m in diameters are homogeneously distributed over the whole cross-sectional area of a fully glassy matrix. Under compressive deformation, the porous alloys with porosities exceeding 40% did not show macroscopic fracture in a wide compressive strain range up to 0.6 whereas the non-porous alloy fractures instantly after elastic limit of about 0.02. Porous bulk glassy alloys exhibit higher plateau stress, lower Young‧s modulus and higher energy absorption capacity compared with the conventional crystalline metal foams.

  15. 46 CFR 90.05-35 - Flammable and combustible liquid cargo in bulk.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Miscellaneous Vessels, such as cable, salvage, pile-driving, and oil-drilling-rig vessels: (1) Grades B, C, D...: Requirements for double hull construction for vessels carrying oil, as defined in 33 CFR 157.03, in bulk as cargo are found in 33 CFR 157.10d. Vessels inspected and certificated under this subchapter may...

  16. 46 CFR 90.05-35 - Flammable and combustible liquid cargo in bulk.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Miscellaneous Vessels, such as cable, salvage, pile-driving, and oil-drilling-rig vessels: (1) Grades B, C, D...: Requirements for double hull construction for vessels carrying oil, as defined in 33 CFR 157.03, in bulk as cargo are found in 33 CFR 157.10d. Vessels inspected and certificated under this subchapter may...

  17. 46 CFR 90.05-35 - Flammable and combustible liquid cargo in bulk.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Miscellaneous Vessels, such as cable, salvage, pile-driving, and oil-drilling-rig vessels: (1) Grades B, C, D...: Requirements for double hull construction for vessels carrying oil, as defined in 33 CFR 157.03, in bulk as cargo are found in 33 CFR 157.10d. Vessels inspected and certificated under this subchapter may...

  18. 46 CFR 90.05-35 - Flammable and combustible liquid cargo in bulk.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Miscellaneous Vessels, such as cable, salvage, pile-driving, and oil-drilling-rig vessels: (1) Grades B, C, D...: Requirements for double hull construction for vessels carrying oil, as defined in 33 CFR 157.03, in bulk as cargo are found in 33 CFR 157.10d. Vessels inspected and certificated under this subchapter may...

  19. 46 CFR 90.05-35 - Flammable and combustible liquid cargo in bulk.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Miscellaneous Vessels, such as cable, salvage, pile-driving, and oil-drilling-rig vessels: (1) Grades B, C, D...: Requirements for double hull construction for vessels carrying oil, as defined in 33 CFR 157.03, in bulk as cargo are found in 33 CFR 157.10d. Vessels inspected and certificated under this subchapter may...

  20. [Driving ability with multiple sclerosis].

    PubMed

    Küst, J; Dettmers, C

    2014-07-01

    Driving is an important issue for young patients, especially for those whose walking capacity is impaired. Driving might support the patient's social and vocational participation. The question as to whether a patient with multiple sclerosis (MS) is restricted in the ability to drive a car depends on neurological and neuropsychological deficits, self-awareness, insight into deficits and ability to compensate for loss of function. Because of the enormous variability of symptoms in MS the question is highly individualized. A practical driving test under supervision of a driving instructor (possibly accompanied by a neuropsychologist) might be helpful in providing both patient and relatives adequate feedback on driving abilities. PMID:24906536

  1. What drives the time evolution of the spacetime geometry?

    NASA Astrophysics Data System (ADS)

    Padmanabhan, T.

    2014-06-01

    I show that in a general, dynamic spacetime, the rate of change of gravitational momentum is related to the difference between the number of bulk and boundary degrees of freedom. All static spacetimes maintain holographic equipartition; i.e. in these spacetimes, the number of degrees of freedom in the boundary is equal to the number of degrees of freedom in the bulk. It is the departure from holographic equipartition that drives the time evolution of the spacetime. This result, which is equivalent to Einstein's equations, provides an elegant, holographic, description of spacetime dynamics.

  2. Variable-reluctance motor drives for electric vehicle propulsion

    NASA Astrophysics Data System (ADS)

    Lang, J. H.; Vallese, F. J.

    1985-05-01

    A methodology is presented for the design of a variable reluctance motor drive having high specific torque, power output and efficiency. Models are developed that describe the magnetic terminal relations of the VRM. These models are based on a flux-tube analysis that is motivated by numerically obtained finite-difference magnetic simulations. The result is a model for the flux-linkage/phase-current characteristic of the VRM. Intrinsic to this model is the estimation of maximum and minimum inductance as well the incremental inductance during bulk saturation. Also fundamental is the behavior of the flux linkage during local pole-tip saturation and due to bulk core saturation. The drive-oriented treatment of modelling and design uncovered important design interactions between the VRM, its inverter, and its excitation. The experimental 3.8-kW drive operated as expected, verifying the models and the design optimizations developed for VRM drives. These experimental results were projected to the 60-kW level, indicating that a 60-kW drive could be constructed with a VRM having a mass of approximately 65 kg, and an efficiency in excess of 95% at and below peak power output.

  3. Drive-by-Downloads

    SciTech Connect

    Narvaez, Julia; Endicott-Popovsky, Barbara E.; Seifert, Christian; Aval, Chiraag U.; Frincke, Deborah A.

    2010-02-01

    Abstract: Drive-by-downloads are malware that push, and then execute, malicious code on a client system without the user's consent. The purpose of this paper is to introduce a discussion of the usefulness of antivirus software for detecting the installation of such malware, providing groundwork for future studies. Client honeypots collected drive-by malware which was then evaluated using common antivirus products. Initial analysis showed that most of such antivirus products identified less than 70% of these highly polymorphic malware programs. Also, it was observed that the antivirus products tested, even when successfully detecting this malware, often failed to classify it, leading to the conclusion that further work could involve not only developing new behavioral detection technologies, but also empirical studies that improve general understanding of these threats. Toward that end, one example of malicious code was analyzed behaviorally to provide insight into next steps for the future direction of this research.

  4. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1990-01-01

    Developing magnetostrictive direct drive research motors to power robot joints is discussed. These type motors are expected to produce extraordinary torque density, to be able to perform microradian incremental steps and to be self-braking and safe with the power off. Several types of motor designs have been attempted using magnetostrictive materials. One of the candidate approaches (the magnetostrictive roller drive) is described. The method in which the design will function is described as is the reason why this approach is inherently superior to the other approaches. Following this, the design will be modelled and its expected performance predicted. This particular candidate design is currently undergoing detailed engineering with prototype construction and testing scheduled for mid 1991.

  5. Variable speed drive

    NASA Technical Reports Server (NTRS)

    Obler, H. D. (Inventor)

    1983-01-01

    A variable speed drive wherein a first embodiment is comprised of a pivotally mounted prime mover coupled to a rotary fluid output device, such as a fan or pump, through a variable and fixed pulley drive arrangement is described. The pivotal position of the prime mover and accordingly the pitch diameter of variable pulley means is controlled in accordance with fluid motor means coupled to the prime mover. This is actuated in response to a fluid feedback control signal derived from a sensed output of the rotary fluid output device. The pivotal motion of the prime mover imparts an arcuate motion to the variable pulley means which effects a speed variation of the rotary fluid output device in accordance with the variation of the pitch diameter ratio of opposing variable and fixed pulley means.

  6. Sex chromosome drive.

    PubMed

    Helleu, Quentin; Gérard, Pierre R; Montchamp-Moreau, Catherine

    2015-02-01

    Sex chromosome drivers are selfish elements that subvert Mendel's first law of segregation and therefore are overrepresented among the products of meiosis. The sex-biased progeny produced then fuels an extended genetic conflict between the driver and the rest of the genome. Many examples of sex chromosome drive are known, but the occurrence of this phenomenon is probably largely underestimated because of the difficulty to detect it. Remarkably, nearly all sex chromosome drivers are found in two clades, Rodentia and Diptera. Although very little is known about the molecular and cellular mechanisms of drive, epigenetic processes such as chromatin regulation could be involved in many instances. Yet, its evolutionary consequences are far-reaching, from the evolution of mating systems and sex determination to the emergence of new species. PMID:25524548

  7. Forces Driving Chaperone Action.

    PubMed

    Koldewey, Philipp; Stull, Frederick; Horowitz, Scott; Martin, Raoul; Bardwell, James C A

    2016-07-14

    It is still unclear what molecular forces drive chaperone-mediated protein folding. Here, we obtain a detailed mechanistic understanding of the forces that dictate the four key steps of chaperone-client interaction: initial binding, complex stabilization, folding, and release. Contrary to the common belief that chaperones recognize unfolding intermediates by their hydrophobic nature, we discover that the model chaperone Spy uses long-range electrostatic interactions to rapidly bind to its unfolded client protein Im7. Short-range hydrophobic interactions follow, which serve to stabilize the complex. Hydrophobic collapse of the client protein then drives its folding. By burying hydrophobic residues in its core, the client's affinity to Spy decreases, which causes client release. By allowing the client to fold itself, Spy circumvents the need for client-specific folding instructions. This mechanism might help explain how chaperones can facilitate the folding of various unrelated proteins. PMID:27293188

  8. Advanced Motor Drives Studies

    NASA Technical Reports Server (NTRS)

    Ehsani, M.; Tchamdjou, A.

    1997-01-01

    This report presents an evaluation of advanced motor drive systems as a replacement for the hydrazine fueled APU units. The replacement technology must meet several requirements which are particular to the space applications and the Orbiter in general. Some of these requirements are high efficiency, small size, high power density. In the first part of the study several motors are compared, based on their characteristics and in light of the Orbiter requirements. The best candidate, the brushless DC is chosen because of its particularly good performance with regards to efficiency. Several power electronics drive technologies including the conventional three-phase hard switched and several soft-switched inverters are then presented. In the last part of the study, a soft-switched inverter is analyzed and compared to its conventional hard-switched counterpart. Optimal efficiency is a basic requirement for space applications and the soft-switched technology represents an unavoidable trend for the future.

  9. Tangled Magnetic Fields in Black Hole Accretion Disks: Implications for Viscosity and Particle Acceleration

    NASA Astrophysics Data System (ADS)

    Subramanian, Prasad

    1997-12-01

    accretion disks, the interaction of energetic protons with kinks in the tangled magnetic field may provide the dominant viscosity mechanism. It also turns out that the collisions of protons with kinks in the magnetic field (which act as scattering centers embedded in the overall shear flow) results in second-order Fermi acceleration of the protons. The acceleration is effective in a tenuous corona above the disk midplane, and results in the formation of an acceleration-enhanced tail to the proton distribution. The pressure in the tail is sufficient to power a relativistic outflow that can attain bulk Lorentz factors between a few and ~10 at large distances from the central object.

  10. Gear Drive Testing

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Philadelphia Gear Corporation used two COSMIC computer programs; one dealing with shrink fit analysis and the other with rotor dynamics problems in computerized design and test work. The programs were used to verify existing in-house programs to insure design accuracy by checking its company-developed computer methods against procedures developed by other organizations. Its specialty is in custom units for unique applications, such as Coast Guard ice breaking ships, steel mill drives, coal crusher, sewage treatment equipment and electricity.

  11. Driving on the Descartes

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut John W. Young, Apollo 16 mission commander, drives the 'Rover', Lunar Roving Vehicle (LRV) to its final parking place near the end of the third extravehicular activity (EVA-3) at the Descartes landing site. Astronaut Charles M. Duke Jr., Lunar Module pilot, took this photograph looking southward. The flank of Stone Mountain can be seen on the horizon at left. The shadow of the Lunar Module 'Orion' is visible in the foreground.

  12. Variable reluctance drive system

    SciTech Connect

    Lipo, T.A.; Liang, F.

    1995-10-17

    A variable reluctance drive system including a motor and corresponding converter for improved current commutation is described. The motor incorporates a salient pole rotor and a salient pole stator having one or more full pitch windings which operate by mutual inductance to transfer the current from the active short pitch winding following phase alignment. This increases output torque and/or speed and permits a number of simple and economical converter circuits. 17 figs.

  13. [Automobile driving capacity in dementia].

    PubMed

    Seeger, Rolf

    2015-04-01

    Dementia influences at an early stage the driving aptitude of motor vehicle steering persons. Every year in Switzerland, around 16'000 driving permit holders suffer newly from dementia; therefore the driving aptitude is questioned, especially because of possibly limited executive functions. Individuals with early-stage dementia often may show a dangerous driving stile. However, a mild dementia does not a priori exclude the driving aptitude, and less than half of these drivers can continue driving for another 1 - 3 years. In contrast, there is no further driving aptitude in presence of moderate dementia. In the assessment of driving aptitude, the underlying cause of dementia is always taken into account. Cognitive short tests such as the Mini-Mental Status Exam, Clock Drawing Test and Trail-Making Test are not suitable to make reliable statements about the aptitude to drive, but these tests are very important for the initial diagnosis of dementia in primary care practice and can lead the way for further examination concerning driving aptitude. The legally prescribed regular check-up for motorists aged over 70 years in Switzerland provides an ideal opportunity for early detection of incipient dementia. The practical procedure for the assessment of aptitude to drive in the primary care practice is presented. The physician-guided on-road driving test represents a meaningful, practical and relatively cost-effective tool for the evaluation of driving aptitude in cases of doubt. PMID:25791047

  14. Bulk Moisture and Salinity Sensor

    NASA Technical Reports Server (NTRS)

    Nurge, Mark; Monje, Oscar; Prenger, Jessica; Catechis, John

    2013-01-01

    Measurement and feedback control of nutrient solutions in plant root zones is critical to the development of healthy plants in both terrestrial and reduced-gravity environments. In addition to the water content, the amount of fertilizer in the nutrient solution is important to plant health. This typically requires a separate set of sensors to accomplish. A combination bulk moisture and salinity sensor has been designed, built, and tested with different nutrient solutions in several substrates. The substrates include glass beads, a clay-like substrate, and a nutrient-enriched substrate with the presence of plant roots. By measuring two key parameters, the sensor is able to monitor both the volumetric water content and salinity of the nutrient solution in bulk media. Many commercially available moisture sensors are point sensors, making localized measurements over a small volume at the point of insertion. Consequently, they are more prone to suffer from interferences with air bubbles, contact area of media, and root growth. This makes it difficult to get an accurate representation of true moisture content and distribution in the bulk media. Additionally, a network of point sensors is required, increasing the cabling, data acquisition, and calibration requirements. measure the dielectric properties of a material in the annular space of the vessel. Because the pore water in the media often has high salinity, a method to measure the media moisture content and salinity simultaneously was devised. Characterization of the frequency response for capacitance and conductance across the electrodes was completed for 2-mm glass bead media, 1- to 2-mm Turface (a clay like media), and 1- to 2-mm fertilized Turface with the presence of root mass. These measurements were then used to find empirical relationships among capacitance (C), the dissipation factor (D), the volumetric water content, and the pore water salinity.

  15. Who's Driving Home?: Assessing Adolescent Drinking and Driving.

    ERIC Educational Resources Information Center

    Swisher, John D.; Bibeau, Daniel

    1987-01-01

    Data from 13,998 students revealed that high percentages of students drank often and that many of these students reported being drunk often. While most students indicated they would prefer not to drive home after drinking, approximately one-third of driving age students indicated they would drive under the influence of alcohol or would ride with…

  16. Shear viscosity of shocked metals at mega-bar pressures

    NASA Astrophysics Data System (ADS)

    Liu, Fu-Sheng

    2013-06-01

    Viscosity of metals at high pressures and temperatures has been one of the most concerned problems in weapon physics and geophysics, e.g., the shear viscosity coefficients of substances in earth's mantle and earth's core at mega-bar pressures are needed for understanding the core mantle convection in deep earth. But the experimental data is very scarce because the conventional measurement methods can hardly be applied to such compression conditions [1]. In this talk, the principle of small-disturbance perturbation method [2] is re-investigated based on both the analytic solution and the numerical solution of the two-dimentional shock flow of sinusoidal distubance on front. In numerical solution, the real viscosity, which governs the flow behind the shock front and the perturbation damping feature, and the artificial viscosity, whick controls the numerical oscillation, separately treated. The relation between the viscosity of flow and the damping features of perturbation amplitude is quantitatively established for the loading situations of Sakharov's [3] and a flyer-impact situation with a finite disturbance. The later is the theoretical basis to develop a new experimental method, called the flyer-impact small-disturbance method [4]. In the flyer-impact small-disturbance method, the two-stage light-gas gun is used to launch a metal flyer. When the flyer directly impacts on the wedge-shaped sample with a sinusoidal surface, a two-dimensional shock flow of sinusoidal distubance on its front is generated. The amplitude of disturbance and its dependance with propagation distance is measured by use of an electric pin-array probe or a fibre-array probe. Correspondingly, the solution of the flow is given by numerically solving the hydrodynamic equations by the finite difference technique to find out the quantative correlations among the amplitude decay, the initial distribution of flow, the amplitude of initial disturbance, the shear viscosity of the flow, and the material

  17. Plate tectonics simulations using reduced viscosity contrasts - The simple approach?

    NASA Astrophysics Data System (ADS)

    Noack, L.; Breuer, D.

    2012-04-01

    In the last decades, more and more studies focussed on the simulation of plate tectonics for Earth and other terrestrial planets inside and outside the solar system. But only the recent development of new robust codes (e.g. GAIA [1] or RHEA [2]) and the usage of super-computers shifted the investigation of planetary mantles into more realistic regimes. One of the problems that many codes still cannot handle is the large viscosity contrast (global or local cell-to-cell contrasts) expected for terrestrial planets and the viscosity is typically simplified [3]. On Earth, the expected contrast varies with 10 or more orders of magnitude. On planets with higher mantle temperatures (e.g. as can be expected for young super-Earths), this viscosity contrast may be even higher with steeper viscosity gradients at the lower boundary of the lithosphere. To solve this problem one can either use a larger nondimensional surface temperature in the Arrhenius viscosity law (or analogously a smaller activation energy) or linearize the exponent of the viscosity, leading to the so-called Frank-Kamenetskii approximation. Several codes use one of these two approximations to be able to simulate terrestrial planets and try to investigate the trend of the likeliness of processes like plate tectonics, depending on factors as surface temperature, internal heating, or mantle thickness. However, our findings propose that the trends observed with these viscosity approximations differ from the ones obtained with the Newtonian Arrhenius law. The first observation is that the approximations lead more easily to plate tectonics than the Arrhenius law. In addition, the dependence of the critical yield stress (i.e. where the transition from plate-tectonics regime to stagnant-lid regime takes place) on the Rayleigh number strongly differs, and the plate tectonics regime is much more easily obtained than for the Arrhenius viscosity. The difference increases with planetary radius. Note, that a more realistic

  18. A General Viscosity Model for Molten Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Gan, Lei; Lai, Chaobin

    2014-06-01

    Blast furnace slag is the most abundant slag in the steel industry. Its metallurgical properties are determined to a great extent by its viscosity. Therefore, it is necessary to establish a reliable viscosity model for blast furnace slag. In the current work, a simple, accurate, and physically meaningful viscosity model for a wide composition range of blast furnace slags is developed based on the Vogel-Fulcher-Tammann (VFT) equation: log η = A + B/( T - C). The model is calibrated by a database containing 365 compositions and 1233 measurements of synthetic and industrial slags. The parameter A has a value of -3.10. The parameters B and C are related to the mass fraction ratio of (CaO + MgO) to (SiO2 + Al2O3) and liquidus temperature of the slag, respectively. Present viscosity model accurately predicts the viscosity of blast furnace slag with relative average error (Δ) of 0.211 (±0.180) and root mean square error (RMSE) of 0.239 Pa·s. A slight modification of this model can also predict the glass transition temperature of blast furnace slag satisfactorily.

  19. Viscosity and thermal conductivity of stable graphite suspensions near percolation.

    PubMed

    Ma, Lei; Wang, Jianjian; Marconnet, Amy M; Barbati, Alexander C; McKinley, Gareth H; Liu, Wei; Chen, Gang

    2015-01-14

    Nanofluids have received much attention in part due to the range of properties possible with different combinations of nanoparticles and base fluids. In this work, we measure the viscosity of suspensions of graphite particles in ethylene glycol as a function of the volume fraction, shear rate, and temperature below and above the percolation threshold. We also measure and contrast the trends observed in the viscosity with increasing volume fraction to the thermal conductivity behavior of the same suspensions: above the percolation threshold, the slope that describes the rate of thermal conductivity enhancement with concentration reduces compared to below the percolation threshold, whereas that of the viscosity enhancement increases. While the thermal conductivity enhancement is independent of temperature, the viscosity changes show a strong dependence on temperature and exhibit different trends with respect to the temperature at different shear rates above the percolation threshold. Interpretation of the experimental observations is provided within the framework of Stokesian dynamics simulations of the suspension microstructure and suggests that although diffusive contributions are not important for the observed thermal conductivity enhancement, they are important for understanding the variations in the viscosity with changes of temperature and shear rate above the percolation threshold. The experimental results can be collapsed to a single master curve through calculation of a single dimensionless parameter (a Péclet number based on the rotary diffusivity of the graphite particles). PMID:25469709

  20. Structural and molecular basis of starch viscosity in hexaploid wheat.

    PubMed

    Ral, J-P; Cavanagh, C R; Larroque, O; Regina, A; Morell, M K

    2008-06-11

    Wheat starch is considered to have a low paste viscosity relative to other starches. Consequently, wheat starch is not preferred for many applications as compared to other high paste viscosity starches. Increasing the viscosity of wheat starch is expected to increase the functionality of a range of wheat flour-based products in which the texture is an important aspect of consumer acceptance (e.g., pasta, and instant and yellow alkaline noodles). To understand the molecular basis of starch viscosity, we have undertaken a comprehensive structural and rheological analysis of starches from a genetically diverse set of wheat genotypes, which revealed significant variation in starch traits including starch granule protein content, starch-associated lipid content and composition, phosphate content, and the structures of the amylose and amylopectin fractions. Statistical analysis highlighted the association between amylopectin chains of 18-25 glucose residues and starch pasting properties. Principal component analysis also identified an association between monoesterified phosphate and starch pasting properties in wheat despite the low starch-phosphate level in wheat as compared to tuber starches. We also found a strong negative correlation between the phosphate ester content and the starch content in flour. Previously observed associations between internal starch granule fatty acids and the swelling peak time and pasting temperature have been confirmed. This study has highlighted a range of parameters associated with increased starch viscosity that could be used in prebreeding/breeding programs to modify wheat starch pasting properties. PMID:18459791