An analytical equation of state for describing isotropic-nematic phase equilibria of Lennard-Jones chain fluids with variable degree of molecular flexibility

NASA Astrophysics Data System (ADS)

van Westen, Thijs; Oyarzún, Bernardo; Vlugt, Thijs J. H.; Gross, Joachim

2015-06-01

We develop an equation of state (EoS) for describing isotropic-nematic (IN) phase equilibria of Lennard-Jones (LJ) chain fluids. The EoS is developed by applying a second order Barker-Henderson perturbation theory to a reference fluid of hard chain molecules. The chain molecules consist of tangentially bonded spherical segments and are allowed to be fully flexible, partially flexible (rod-coil), or rigid linear. The hard-chain reference contribution to the EoS is obtained from a Vega-Lago rescaled Onsager theory. For the description of the (attractive) dispersion interactions between molecules, we adopt a segment-segment approach. We show that the perturbation contribution for describing these interactions can be divided into an "isotropic" part, which depends only implicitly on orientational ordering of molecules (through density), and an "anisotropic" part, for which an explicit dependence on orientational ordering is included (through an expansion in the nematic order parameter). The perturbation theory is used to study the effect of chain length, molecular flexibility, and attractive interactions on IN phase equilibria of pure LJ chain fluids. Theoretical results for the IN phase equilibrium of rigid linear LJ 10-mers are compared to results obtained from Monte Carlo simulations in the isobaric-isothermal (NPT) ensemble, and an expanded formulation of the Gibbs-ensemble. Our results show that the anisotropic contribution to the dispersion attractions is irrelevant for LJ chain fluids. Using the isotropic (density-dependent) contribution only (i.e., using a zeroth order expansion of the attractive Helmholtz energy contribution in the nematic order parameter), excellent agreement between theory and simulations is observed. These results suggest that an EoS contribution for describing the attractive part of the dispersion interactions in real LCs can be obtained from conventional theoretical approaches designed for isotropic fluids, such as a Perturbed

Idealized modeling of convective organization with changing sea surface temperatures using multiple equilibria in weak temperature gradient simulations

NASA Astrophysics Data System (ADS)

Sentić, Stipo; Sessions, Sharon L.

2017-06-01

The weak temperature gradient (WTG) approximation is a method of parameterizing the influences of the large scale on local convection in limited domain simulations. WTG simulations exhibit multiple equilibria in precipitation; depending on the initial moisture content, simulations can precipitate or remain dry for otherwise identical boundary conditions. We use a hypothesized analogy between multiple equilibria in precipitation in WTG simulations, and dry and moist regions of organized convection to study tropical convective organization. We find that the range of wind speeds that support multiple equilibria depends on sea surface temperature (SST). Compared to the present SST, low SSTs support a narrower range of multiple equilibria at higher wind speeds. In contrast, high SSTs exhibit a narrower range of multiple equilibria at low wind speeds. This suggests that at high SSTs, organized convection might occur with lower surface forcing. To characterize convection at different SSTs, we analyze the change in relationships between precipitation rate, atmospheric stability, moisture content, and the large-scale transport of moist entropy and moisture with increasing SSTs. We find an increase in large-scale export of moisture and moist entropy from dry simulations with increasing SST, which is consistent with a strengthening of the up-gradient transport of moisture from dry regions to moist regions in organized convection. Furthermore, the changes in diagnostic relationships with SST are consistent with more intense convection in precipitating regions of organized convection for higher SSTs.

Gas chemistry of Icelandic thermal fluids

NASA Astrophysics Data System (ADS)

Stefánsson, Andri

2017-10-01

The chemistry of gases in thermal fluids from Iceland was studied in order to evaluate the sources and processes affecting volatile concentrations in volcanic geothermal systems at divergent plate boundaries. The fluids included vapor fumaroles and two-phase well discharges with temperatures of 100-340 °C. The vapor was dominated by H2O accounting for 62-100 mol% and generally for > 99 mol%, with CO2, H2S and H2 being the dominant gases followed by N2, CH4, and Ar. Overall mineral-gas and gas-gas equilibria were not observed for the major gases, including CO2, H2S, H2 and CH4 within the geothermal reservoirs. Instead the system proved to be controlled by source(s) and their ratios and various metastable equilibria along a fluid-rock reaction progress with gas concentrations controlled by such metastable equilibria varying at particular temperatures as a functional extent of reaction. The concentrations of H2S and H2 closely reflect mineral-fluid metastable equilibria, whereas CO2 concentrations are controlled by the input of magma gas corresponding to > 0.1 to < 5% mass input. With fluid ascent to the surface, boiling and condensation may occur, further changing the gas concentrations and hence surface fumaroles may not reflect the reservoir fluid characteristics but rather secondary processes.

Axisymmetric Plasma Equilibria in General Relativity

NASA Astrophysics Data System (ADS)

Elsässer, Klaus

Axisymmetric plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species; they remain arbitrary if no gain and loss processes are considered, in close analogy to the free flux functions in ideal magnetohydrodynamics. Several simplifying assumptions allow the reduction of the basic equations to one single scalar equation for the stream function χ of positrons or ions, respectively, playing the rôle of the Grad/Shafranov equation in magnetohydrodynamics; in particular, Maxwell's equations can be solved analytically for a quasineutral plasma when both the charge density and the toroidal electric current density are negligible (in contrast to the Tokamak situation). The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio me/mi. The χ-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.

Local invariants in non-ideal flows of neutral fluids and two-fluid plasmas

NASA Astrophysics Data System (ADS)

Zhu, Jian-Zhou

2018-03-01

The main objective is the locally invariant geometric object of any (magneto-)fluid dynamics with forcing and damping (nonideal), while more attention is paid to the untouched dynamical properties of two-fluid fashion. Specifically, local structures, beyond the well-known "frozen-in" to the barotropic flows of the generalized vorticities, of the two-fluid model of plasma flows are presented. More general non-barotropic situations are also considered. A modified Euler equation [T. Tao, "Finite time blowup for Lagrangian modifications of the three-dimensional Euler equation," Ann. PDE 2, 9 (2016)] is also accordingly analyzed and remarked from the angle of view of the two-fluid model, with emphasis on the local structures. The local constraints of high-order differential forms such as helicity, among others, find simple formulation for possible practices in modeling the dynamics. Thus, the Cauchy invariants equation [N. Besse and U. Frisch, "Geometric formulation of the Cauchy invariants for incompressible Euler flow in flat and curved spaces," J. Fluid Mech. 825, 412 (2017)] may be enabled to find applications in non-ideal flows. Some formal examples are offered to demonstrate the calculations, and particularly interestingly the two-dimensional-three-component (2D3C) or the 2D passive scalar problem presents that a locally invariant Θ = 2θζ, with θ and ζ being, respectively, the scalar value of the "vertical velocity" (or the passive scalar) and the "vertical vorticity," may be used as if it were the spatial density of the globally invariant helicity, providing a Lagrangian prescription to control the latter in some situations of studying its physical effects in rapidly rotating flows (ubiquitous in atmosphere of astrophysical objects) with marked 2D3C vortical modes or in purely 2D passive scalars.

Spontaneous decay of periodic magnetostatic equilibria

DOE PAGES

East, William E.; Zrake, Jonathan; Yuan, Yajie; ...

2015-08-28

In order to understand the conditions which lead a highly magnetized, relativistic plasma to become unstable, and in such cases how the plasma evolves, we study a prototypical class of magnetostatic equilibria where the magnetic field satisfies ∇ x B = αB , where \\alpha is spatially uniform, on a periodic domain. Using numerical solutions we show that generic examples of such equilibria are unstable to ideal modes (including incompressible ones) which are marked by exponential growth in the linear phase. We characterize the unstable mode, showing how it can be understood in terms of merging magnetic and current structures,more » and explicitly demonstrate its instability using the energy principle. Following the nonlinear evolution of these solutions, we find that they rapidly develop regions with relativistic velocities and electric fields of comparable magnitude to the magnetic field, liberating magnetic energy on dynamical timescales and eventually settling into a configuration with the largest allowable wavelength. Furthermore, these properties make such solutions a promising setting for exploring the mechanisms behind extreme cosmic sources of gamma rays.« less

A fast numerical method for ideal fluid flow in domains with multiple stirrers

NASA Astrophysics Data System (ADS)

Nasser, Mohamed M. S.; Green, Christopher C.

2018-03-01

A collection of arbitrarily-shaped solid objects, each moving at a constant speed, can be used to mix or stir ideal fluid, and can give rise to interesting flow patterns. Assuming these systems of fluid stirrers are two-dimensional, the mathematical problem of resolving the flow field—given a particular distribution of any finite number of stirrers of specified shape and speed—can be formulated as a Riemann-Hilbert (R-H) problem. We show that this R-H problem can be solved numerically using a fast and accurate algorithm for any finite number of stirrers based around a boundary integral equation with the generalized Neumann kernel. Various systems of fluid stirrers are considered, and our numerical scheme is shown to handle highly multiply connected domains (i.e. systems of many fluid stirrers) with minimal computational expense.

Ideal relaxation of the Hopf fibration

NASA Astrophysics Data System (ADS)

Smiet, Christopher Berg; Candelaresi, Simon; Bouwmeester, Dirk

2017-07-01

Ideal magnetohydrodynamics relaxation is the topology-conserving reconfiguration of a magnetic field into a lower energy state where the net force is zero. This is achieved by modeling the plasma as perfectly conducting viscous fluid. It is an important tool for investigating plasma equilibria and is often used to study the magnetic configurations in fusion devices and astrophysical plasmas. We study the equilibrium reached by a localized magnetic field through the topology conserving relaxation of a magnetic field based on the Hopf fibration in which magnetic field lines are closed circles that are all linked with one another. Magnetic fields with this topology have recently been shown to occur in non-ideal numerical simulations. Our results show that any localized field can only attain equilibrium if there is a finite external pressure, and that for such a field a Taylor state is unattainable. We find an equilibrium plasma configuration that is characterized by a lowered pressure in a toroidal region, with field lines lying on surfaces of constant pressure. Therefore, the field is in a Grad-Shafranov equilibrium. Localized helical magnetic fields are found when plasma is ejected from astrophysical bodies and subsequently relaxes against the background plasma, as well as on earth in plasmoids generated by, e.g., a Marshall gun. This work shows under which conditions an equilibrium can be reached and identifies a toroidal depression as the characteristic feature of such a configuration.

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

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

A note on two-dimensional asymptotic magnetotail equilibria

NASA Technical Reports Server (NTRS)

Voigt, Gerd-Hannes; Moore, Brian D.

1994-01-01

In order to understand, on the fluid level, the structure, the time evolution, and the stability of current sheets, such as the magnetotail plasma sheet in Earth's magnetosphere, one has to consider magnetic field configurations that are in magnetohydrodynamic (MHD) force equilibrium. Any reasonable MHD current sheet model has to be two-dimensional, at least in an asymptotic sense (B(sub z)/B (sub x)) = epsilon much less than 1. The necessary two-dimensionality is described by a rather arbitrary function f(x). We utilize the free function f(x) to construct two-dimensional magnetotail equilibria are 'equivalent' to current sheets in empirical three-dimensional models. We obtain a class of asymptotic magnetotail equilibria ordered with respect to the magnetic disturbance index Kp. For low Kp values the two-dimensional MHD equilibria reflect some of the realistic, observation-based, aspects of three-dimensional models. For high Kp values the three-dimensional models do not fit the asymptotic MHD equlibria, which is indicative of their inconsistency with the assumed pressure function. This, in turn, implies that high magnetic activity levels of the real magnetosphere might be ruled by thermodynamic conditions different from local thermodynamic equilibrium.

Simulation of phase equilibria

NASA Astrophysics Data System (ADS)

Martin, Marcus Gary

The focus of this thesis is on the use of configurational bias Monte Carlo in the Gibbs ensemble. Unlike Metropolis Monte Carlo, which is reviewed in chapter I, configurational bias Monte Carlo uses an underlying Markov chain transition matrix which is asymmetric in such a way that it is more likely to attempt to move to a molecular conformation which has a lower energy than to one with a higher energy. Chapter II explains how this enables efficient simulation of molecules with complex architectures (long chains and branched molecules) for coexisting fluid phases (liquid, vapor, or supercritical), and also presents several of our recent extensions to this method. In chapter III we discuss the development of the Transferable Potentials for Phase Equilibria United Atom (TraPPE-UA) force field which accurately describes the fluid phase coexistence for linear and branched alkanes. Finally, in the fourth chapter the methods and the force field are applied to systems ranging from supercritical extraction to gas chromatography to illustrate the power and versatility of our approach.

Beltrami–Bernoulli equilibria in plasmas with degenerate electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berezhiani, V. I., E-mail: vazhab@yahoo.com; Shatashvili, N. L., E-mail: shatash@ictp.it; Mahajan, S. M., E-mail: mahajan@mail.utexas.edu

2015-02-15

A new class of Double Beltrami–Bernoulli equilibria, sustained by electron degeneracy pressure, is investigated. It is shown that due to electron degeneracy, a nontrivial Beltrami–Bernoulli equilibrium state is possible even for a zero temperature plasma. These states are, conceptually, studied to show the existence of new energy transformation pathways converting, for instance, the degeneracy energy into fluid kinetic energy. Such states may be of relevance to compact astrophysical objects like white dwarfs, neutron stars, etc.

Theoretical models of non-Maxwellian equilibria for one-dimensional collisionless plasmas

NASA Astrophysics Data System (ADS)

Allanson, O.; Neukirch, T.; Wilson, F.; Troscheit, S.

2016-12-01

It is ideal to use exact equilibrium solutions of the steady state Vlasov-Maxwell system to intialise collsionless simulations. However, exact equilibrium distribution functions (DFs) for a given macroscopic configuration are typically unknown, and it is common to resort to using `flow-shifted' Maxwellian DFs in their stead. These DFs may be consistent with a macrosopic system with the target number density and current density, but could well have inaccurate higher order moments. We present recent theoretical work on the `inverse problem in Vlasov-Maxwell equilibria', namely calculating an exact solution of the Vlasov equation for a specific given magnetic field. In particular, we focus on one-dimensional geometries in Cartesian (current sheets) coordinates.1. From 1D fields to Vlasov equilibria: Theory and application of Hermite Polynomials: (O. Allanson, T. Neukirch, S. Troscheit and F. Wilson, Journal of Plasma Physics, 82, 905820306 (2016) [28 pages, Open Access] )2. An exact collisionless equilibrium for the Force-Free Harris Sheet with low plasma beta: (O. Allanson, T. Neukirch, F. Wilson and S. Troscheit, Physics of Plasmas, 22, 102116 (2015) [11 pages, Open Access])3. Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field (O. Allanson, F. Wilson and T. Neukirch, (2016)) (accepted, Physics of Plasmas)

Effects of density gradient caused by multi-pulsing CHI on two-fluid flowing equilibria of spherical torus plasmas

NASA Astrophysics Data System (ADS)

Kanki, T.; Nagata, M.

2014-10-01

Two-fluid dynamo relaxation is examined to understand sustainment mechanism of spherical torus (ST) plasmas by multi-pulsing CHI (M-CHI) in the HIST device. The steeper density gradient between the central open flux column (OFC) and closed flux regions by applying the second CHI pulse is observed to cause not only the E × B drift but also the ion diamagnetic drift, leading the two-fluid dynamo. The purpose of this study is to investigate the effects of the steep change in the density gradient on the ST equilibria by using the two-fluid equilibrium calculations. The toroidal magnetic field becomes from a diamagnetic to a paramagnetic profile in the closed flux region while it remains a diamagnetic profile in the OFC region. The toroidal ion flow velocity is increased from negative to positive values in the closed flux region. Here, the negative ion flow velocity is the opposite direction to the toroidal current. The poloidal ion flow velocity between the OFC and closed flux regions is increased, because the ion diamagnetic drift velocity is changed in the same direction as the E × B drift velocity through the steeper ion pressure gradient. As a result, the strong shear flow and the paramagnetic toroidal field are generated in the closed flux region. Here, the ion flow velocity is the same direction as the poloidal current. The radial electric field shear between the OFC and closed flux regions is enhanced due to the strong dependence on the magnetic force through the interaction of toroidal ion flow velocity and axial magnetic field. The two-fluid effect is significant there due to the ion diamagnetic effect.

Self-propulsion of free solid bodies with internal rotors via localized singular vortex shedding in planar ideal fluids

NASA Astrophysics Data System (ADS)

Tallapragada, P.; Kelly, S. D.

2015-11-01

Diverse mechanisms for animal locomotion in fluids rely on vortex shedding to generate propulsive forces. This is a complex phenomenon that depends essentially on fluid viscosity, but its influence can be modeled in an inviscid setting by introducing localized velocity constraints to systems comprising solid bodies interacting with ideal fluids. In the present paper, we invoke an unsteady version of the Kutta condition from inviscid airfoil theory and a more primitive stagnation condition to model vortex shedding from a geometrically contrasting pair of free planar bodies representing idealizations of swimming animals or robotic vehicles. We demonstrate with simulations that these constraints are sufficient to enable both bodies to propel themselves with very limited actuation. The solitary actuator in each case is a momentum wheel internal to the body, underscoring the symmetry-breaking role played by vortex shedding in converting periodic variations in a generic swimmer's angular momentum to forward locomotion. The velocity constraints are imposed discretely in time, resulting in the shedding of discrete vortices; we observe the roll-up of these vortices into distinctive wake structures observed in viscous models and physical experiments.

Non-Ideal Compressible Fluid Dynamics: A Challenge for Theory

NASA Astrophysics Data System (ADS)

Kluwick, A.

2017-03-01

The possibility that compression as well as rarefaction shocks may form in single phase vapours was envisaged first by Bethe (1942). However calculations based on the Van der Waals equation of state indicated that the latter type of shock is possible only if the specific heat at constant volume cv divided by the universal gas constant R is larger than about 17.5 which he considered too large to be satisfied by real fluids. This conclusion was contested by Thompson (1971) who showed that the type of shock capable of forming in arbitrary fluids is determined by the sign of the thermodynamic quantity to which he referred to as fundamental derivative of gas dynamics. Here v, p, s and c denote the specific volume, the pressure, the entropy and the speed of sound. Thompson and co-workers also showed that the required condition for the existence of rarefaction shocks, that Γ may take on negative values, is indeed satisfied for a number of hydrocarbon and fluorocarbon vapours. This finding spawned a burst of theoretical studies elaborating on the unusual and often counterintuitive behaviour of shocks with rarefaction shocks present. These produced both results of theoretical character but also results suggesting the practical importance of Non-Ideal Compressible Fluid Dynamics in general. The present paper addresses some of the challenges encountered in connection with the theoretical treatment of the associated flow behaviour. Weakly nonlinear acoustic waves of finite amplitude serve as a starting point. Here mixed rather than strictly positive nonlinearity generates a wealth of phenomena not possible in perfect gases. Examples of steady flows where these non-classical effects play a decisive role (and which may be useful also for future experimental work) are quasi one-dimensional nozzle flows and transonic two-dimensional flows past corners. The study of viscous effects concentrates on laminar flows of boundary layer type. Here non-classical phenomena are caused by the

Phase Equilibria Diagrams Database

National Institute of Standards and Technology Data Gateway

SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

Nonambipolar Transport and Torque in Perturbed Equilibria

NASA Astrophysics Data System (ADS)

Logan, N. C.; Park, J.-K.; Wang, Z. R.; Berkery, J. W.; Kim, K.; Menard, J. E.

2013-10-01

A new Perturbed Equilibrium Nonambipolar Transport (PENT) code has been developed to calculate the neoclassical toroidal torque from radial current composed of both passing and trapped particles in perturbed equilibria. This presentation outlines the physics approach used in the development of the PENT code, with emphasis on the effects of retaining general aspect-ratio geometric effects. First, nonambipolar transport coefficients and corresponding neoclassical toroidal viscous (NTV) torque in perturbed equilibria are re-derived from the first order gyro-drift-kinetic equation in the ``combined-NTV'' PENT formalism. The equivalence of NTV torque and change in potential energy due to kinetic effects [J-K. Park, Phys. Plas., 2011] is then used to showcase computational challenges shared between PENT and stability codes MISK and MARS-K. Extensive comparisons to a reduced model, which makes numerous large aspect ratio approximations, are used throughout to emphasize geometry dependent physics such as pitch angle resonances. These applications make extensive use of the PENT code's native interfacing with the Ideal Perturbed Equilibrium Code (IPEC), and the combination of these codes is a key step towards an iterative solver for self-consistent perturbed equilibrium torque. Supported by US DOE contract #DE-AC02-09CH11466 and the DOE Office of Science Graduate Fellowship administered by the Oak Ridge Institute for Science & Education under contract #DE-AC05-06OR23100.

Axisymmetric plasma equilibria in a Kerr metric

NASA Astrophysics Data System (ADS)

Elsässer, Klaus

2001-10-01

Plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species. The quasi-neutrality assumption (no charge density, no toroidal current) allows to solve Maxwell's equations analytically for any axisymmetric stationary metric, and to reduce the fluid equations to one single scalar equation for the stream function \\chi of the positrons or ions, respectively. The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio m_e/m_i. The \\chi-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.

Pyroxene-melt equilibria. [for lunar maria basalts

NASA Technical Reports Server (NTRS)

Nielsen, R. L.; Drake, M. J.

1979-01-01

A thermodynamic analysis of pyroxene-melt equilibria is performed through use of a literature survey of analyses of high-Ca pyroxene and coexisting silicate melt pairs and analyses of low-Ca pyroxene silicate melt pairs. Reference is made to a modified version of a model developed by Bottinga and Weill (1972) which more successfully accounts for variations in melt composition than does a model which considers the melt to be composed of simple oxides which mix ideally. By using a variety of pyroxene melt relations, several pyroxene-melt and low-Ca pyroxene-high-Ca pyroxene geothermometers are developed which have internally consistant precisions of approximately + or - 20 C. Finally, it is noted that these equations may have application in modeling the evolution of mineral compositions during differentiation of basaltic magmas.

Jump conditions in transonic equilibria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guazzotto, L.; Betti, R.; Jardin, S. C.

2013-04-15

In the present paper, the numerical calculation of transonic equilibria, first introduced with the FLOW code in Guazzotto et al.[Phys. Plasmas 11, 604 (2004)], is critically reviewed. In particular, the necessity and effect of imposing explicit jump conditions at the transonic discontinuity are investigated. It is found that 'standard' (low-{beta}, large aspect ratio) transonic equilibria satisfy the correct jump condition with very good approximation even if the jump condition is not explicitly imposed. On the other hand, it is also found that high-{beta}, low aspect ratio equilibria require the correct jump condition to be explicitly imposed. Various numerical approaches aremore » described to modify FLOW to include the jump condition. It is proved that the new methods converge to the correct solution even in extreme cases of very large {beta}, while they agree with the results obtained with the old implementation of FLOW in lower-{beta} equilibria.« less

Magnetic islands and singular currents at rational surfaces in three-dimensional magnetohydrodynamic equilibria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loizu, J., E-mail: joaquim.loizu@ipp.mpg.de; Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton New Jersey 08543; Hudson, S.

2015-02-15

Using the recently developed multiregion, relaxed MHD (MRxMHD) theory, which bridges the gap between Taylor's relaxation theory and ideal MHD, we provide a thorough analytical and numerical proof of the formation of singular currents at rational surfaces in non-axisymmetric ideal MHD equilibria. These include the force-free singular current density represented by a Dirac δ-function, which presumably prevents the formation of islands, and the Pfirsch-Schlüter 1/x singular current, which arises as a result of finite pressure gradient. An analytical model based on linearized MRxMHD is derived that can accurately (1) describe the formation of magnetic islands at resonant rational surfaces, (2)more » retrieve the ideal MHD limit where magnetic islands are shielded, and (3) compute the subsequent formation of singular currents. The analytical results are benchmarked against numerical simulations carried out with a fully nonlinear implementation of MRxMHD.« less

MHD Studies of Advanced Tokamak Equilibria

NASA Astrophysics Data System (ADS)

Strumberger, E.

2005-10-01

Advanced tokamak scenarios are often characterized by an extremely reversed profile of the safety factor, q, and a fast toroidal rotation. ASDEX Upgrade type equilibria with toroidal flow are computed up to a toroidal Mach number of Mta= 0.5, and compared with the static solution. Using these equilibria, the stabilizing effect of differential toroidal rotation on double tearing modes (DTMs) is investigated. These studies show that the computation of equilibria with flow is necessary for toroidally rotating plasma with Mta>=0.2. The use of ρtor instead of ρpol as radial coordinate enables us also to investigate the stability of equilibria with current holes. For numerical reasons, the rotational transform, = 1/q, has to be unequal zero in the CASTOR$FLOW code, but values of a>=0.001 (qa<=1000) can be easily handled. Stability studies of DTMs in the presence of a current hole are presented. Tokamak equilibria are only approximately axisymmetric. The finite number of toroidal field coils destroys the perfect axisymmetry of the device, and the coils produce a short wavelength ripple in the magnetic field strength. This toroidal field ripple plays a crucial role for the loss of high energy particles. Therefore, three-dimensional tokamak equilibria with and without current holes are computed for various plasma beta values. In addition the influence of the plasma beta on the toroidal field ripple is investigated.

Quasi-Chemical PC-SAFT: An Extended Perturbed Chain-Statistical Associating Fluid Theory for Lattice-Fluid Mixtures.

PubMed

Parvaneh, Khalil; Shariati, Alireza

2017-09-07

In this study, a new modification of the perturbed chain-statistical associating fluid theory (PC-SAFT) has been proposed by incorporating the lattice fluid theory of Guggenheim as an additional term to the original PC-SAFT terms. As the proposed model has one more term than the PC-SAFT, a new mixing rule has been developed especially for the new additional term, while for the conventional terms of the PC-SAFT, the one-fluid mixing rule is used. In order to evaluate the proposed model, the vapor-liquid equilibria were estimated for binary CO 2 mixtures with 16 different ionic liquids (ILs) of the 1-alkyl-3-methylimidazolium family with various anions consisting of bis(trifluoromethylsulfonyl) imide, hexafluorophosphate, tetrafluoroborate, and trifluoromethanesulfonate. For a comprehensive comparison, three different modes (different adjustable parameters) of the proposed model were compared with the conventional PC-SAFT. Results indicate that the proposed modification of the PC-SAFT EoS is generally more reliable with respect to the conventional PC-SAFT in all the three proposed modes of vapor-liquid equilibria, giving good agreement with literature data.

Pedestal-to-Wall 3D Fluid Transport Simulations on DIII-D

DOE PAGES

Lore, Jeremy D.; Wolfmeister, Alexis Briesemeister; Ferraro, Nathaniel M.; ...

2017-03-30

The 3D fluid-plasma edge transport code EMC3-EIRENE is used to test several magnetic field models with and without plasma response against DIII-D experimental data for even and odd-parity n=3 magnetic field perturbations. The field models include ideal and extended MHD equilibria, and the vacuum approximation. Plasma response is required to reduce the stochasticity in the pedestal region for even-parity fields, however too much screening suppresses the measured splitting of the downstream T e profile. Odd-parity perturbations result in weak tearing and only small additional peaks in the downstream measurements. In this case plasma response is required to increase the sizemore » of the lobe structure. Finally, no single model is able to simultaneously reproduce the upstream and downstream characteristics for both odd and even-parity perturbations.« less

Static axisymmetric equilibria in general relativistic magnetohydrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nunez, Manuel

2008-01-15

While the definition of static equilibria is not clear in a general relativistic context, in many cases of astrophysical interest a natural 3+1 split exists which allows us to define physically meaningful spatial and temporal coordinates. We study the possibility of axisymmetric magnetohydrodynamic equilibria in this setting. The presence of a nontrivial shift velocity provides a constraint not present in the Newtonian case, while the momentum equation may be set in a Grad-Shafranov-like form with the presence of additional terms involving the space-time metric coefficients. It is found that whenever the magnetic field or the shift velocity possesses poloidal component,more » the existence of even local static equilibria demands that the metric parameters satisfy such strong conditions that these equilibria are extremely unlikely. Only very particular cases such as purely toroidal fields and shifts yield existence of equilibria, provided we are able to choose arbitrarily the plasma pressure and density.« less

Process of establishing a plane-wave system on ice cover over a dipole moving uniformly in an ideal fluid column

NASA Astrophysics Data System (ADS)

Il'ichev, A. T.; Savin, A. S.

2017-12-01

We consider a planar evolution problem for perturbations of the ice cover by a dipole starting its uniform rectilinear horizontal motion in a column of an initially stationary fluid. Using asymptotic Fourier analysis, we show that at supercritical velocities, waves of two types form on the water-ice interface. We describe the process of establishing these waves during the dipole motion. We assume that the fluid is ideal and incompressible and its motion is potential. The ice cover is modeled by the Kirchhoff-Love plate.

Magnetospheric Reconnection in Modified Current-Sheet Equilibria

NASA Astrophysics Data System (ADS)

Newman, D. L.; Goldman, M. V.; Lapenta, G.; Markidis, S.

2012-10-01

Particle simulations of magnetic reconnection in Earth's magnetosphere are frequently initialized with a current-carrying Harris equilibrium superposed on a current-free uniform background plasma. The Harris equilibrium satisfies local charge neutrality, but requires that the sheet current be dominated by the hotter species -- often the ions in Earth's magnetosphere. This constraint is not necessarily consistent with observations. A modified kinetic equilibrium that relaxes this constraint on the currents was proposed by Yamada et al. [Phys. Plasmas., 7, 1781 (2000)] with no background population. These modified equilibria were characterized by an asymptotic converging or diverging electrostatic field normal to the current sheet. By reintroducing the background plasma, we have developed new families of equilibria where the asymptotic fields are suppressed by Debye shielding. Because the electrostatic potential profiles of these new equilibria contain wells and/or barriers capable of spatially isolating different populations of electrons and/or ions, these solutions can be further generalized to include classes of asymmetric kinetic equilibria. Examples of both symmetric and asymmetric equilibria will be presented. The dynamical evolution of these equilibria, when perturbed, will be further explored by means of implicit 2D PIC reconnection simulations, including comparisons with simulations employing standard Harris-equilibrium initializations.

Self-Similar Apical Sharpening of an Ideal Perfecting Conducting Fluid Subject to Maxwell Stresses

NASA Astrophysics Data System (ADS)

Zhou, Chengzhe; Troian, Sandra M.

2016-11-01

We examine the apical behavior of an ideal, perfectly conducting incompressible fluid surrounded by vacuum in circumstances where the capillary, Maxwell and inertial forces contribute to formation of a liquid cone. A previous model based on potential flow describes a family of self-similar solutions with conic cusps whose interior angles approach the Taylor cone angle. These solutions were obtained by matching powers of the leading order terms in the velocity and electric field potential to the asymptotic form dictated by a stationary cone shape. In re-examining this earlier work, we have found a more important, neglected leading order term in the velocity and field potentials, which satisfies the governing, interfacial and far-field conditions as well. This term allows for the development of additional self-similar, sharpening apical shapes, including time reversed solutions for conic tip recoil after fluid ejection. We outline the boundary-element technique for solving the exact similarity solutions, which have parametric dependence on the far-field conditions, and discuss consequences of our findings.

Thermodynamic assessment of hydrothermal alkali feldspar-mica-aluminosilicate equilibria

USGS Publications Warehouse

Sverjensky, D.A.; Hemley, J.J.; d'Angelo, W. M.

1991-01-01

The thermodynamic properties of minerals retrieved from consideration of solid-solid and dehydration equilibria with calorimetric reference values, and those of aqueous species derived from studies of electrolytes, are not consistent with experimentally measured high-temperature solubilities in the systems K2O- and Na2O-Al2O3-SiO2-H2O-HCl (e.g., K-fs - Ms - Qtz - K+ - H+). This introduces major inaccuracies into the computation of ionic activity ratios and the acidities of diagenetic, metamorphic, and magmatic hydrothermal fluids buffered by alkali silicate-bearing assemblages. We report a thermodynamic analysis of revised solubility equilibria in these systems that integrates the thermodynamic properties of minerals obtained from phase equilibria studies (Berman, 1988) with the properties of aqueous species calculated from a calibrated equation of state (Shock and Helgeson, 1988). This was achieved in two separate steps. First, new values of the free energies and enthalpies of formation at 25??C and 1 bar for the alkali silicates muscovite and albite were retrieved from the experimental solubility equilibria at 300??C and Psat. Because the latter have stoichiometric reaction coefficients different from those for solid-solid and dehydration equilibria, our procedure preserves exactly the relative thermodynamic properties of the alkali-bearing silicates (Berman, 1988). Only simple arithmetic adjustments of -1,600 and -1,626 (??500) cal/mol to all the K- and Na-bearing silicates, respectively, in Berman (1988) are required. In all cases, the revised values are within ??0.2% of calorimetric values. Similar adjustments were derived for the properties of minerals from Helgeson et al. (1978). Second, new values of the dissociation constant of HCl were retrieved from the solubility equilibria at temperatures and pressures from 300-600??C and 0.5-2.0 kbars using a simple model for aqueous speciation. The results agree well with the conductance-derived dissociation

Multiple equilibria, bifurcations and selection scenarios in cosymmetric problem of thermal convection in porous medium

NASA Astrophysics Data System (ADS)

Govorukhin, Vasily N.; Shevchenko, Igor V.

2017-12-01

We study convection in a two-dimensional container of porous material saturated with fluid and heated from below. This problem belongs to the class of dynamical systems with nontrivial cosymmetry. The cosymmetry gives rise to a hidden parameter in the system and continuous families of infinitely many equilibria, and leads to non-trivial bifurcations. In this article we present our numerical studies that demonstrate nonlinear phenomena resulting from the existence of cosymmetry. We give a comprehensive picture of different bifurcations which occur in cosymmetric dynamical systems and in the convection problem. It includes internal and external (as an invariant set) bifurcations of one-parameter families of equilibria, as well as bifurcations leading to periodic, quasiperiodic and chaotic behaviour. The existence of infinite number of stable steady-state regimes begs the important question as to which of them can realize in physical experiments. In this paper, this question (known as the selection problem) is studied in detail. In particular, we show that the selection scenarios strongly depend on the initial temperature distribution of the fluid. The calculations are carried out by the global cosymmetry-preserving Galerkin method, and numerical methods used to analyse cosymmetric systems are also described.

Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX

NASA Astrophysics Data System (ADS)

Banerjee, Debabrata; Zhu, Ping; Maingi, Rajesh

2017-07-01

Linear stability analysis of the national spherical torus experiment (NSTX) Li-conditioned ELM-free H-mode equilibria is carried out in the context of the extended magneto-hydrodynamic (MHD) model in NIMROD. The purpose is to investigate the physical cause behind edge localized mode (ELM) suppression in experiment after the Li-coating of the divertor and the first wall of the NSTX tokamak. Besides ideal MHD modeling, including finite-Larmor radius effect and two-fluid Hall and electron diamagnetic drift contributions, a non-ideal resistivity model is employed, taking into account the increase of Z eff after Li-conditioning in ELM-free H-mode. Unlike an earlier conclusion from an eigenvalue code analysis of these equilibria, NIMROD results find that after reduced recycling from divertor plates, profile modification is necessary but insufficient to explain the mechanism behind complete ELMs suppression in ideal two-fluid MHD. After considering the higher plasma resistivity due to higher Z eff, the complete stabilization could be explained. A thorough analysis of both pre-lithium ELMy and with-lithium ELM-free cases using ideal and non-ideal MHD models is presented, after accurately including a vacuum-like cold halo region in NIMROD to investigate ELMs.

Redox Equilibria Involving Chromium Minerals in Aqueous Fluids in the Deep Earth - Implications for Diamond Formation

NASA Astrophysics Data System (ADS)

Huang, J.; Huang, F.; Hao, J.; Sverjensky, D. A.

2017-12-01

Diamonds are often associated with inclusions of garnet that are characteristically Cr-rich and Ca-poor, suggesting metasomatic reactions involving fluids [1]. To investigate these reactions, we developed a thermodynamic characterization of Cr-bearing minerals and integrated it with our database for the thermodynamic properties of aqueous Cr-species [2]. We retrieved thermodynamic properties of picrochromite (MgCr2O4), and knorringite (Mg3Cr2Si3O12) consistent with minerals in the Berman (1988) using calorimetric data and experimental phase equilibria involving the reactions: MgCr2O4 + SiO2 = Cr2O3 + MgSiO3 [2] and MgCr2O4 + 4MgSiO3 = Mg3Cr2Si3O12 + Mg2SiO4 [3], respectively.At high temperatures and pressures, neutral pH and FMQ, the predicted solubilities of eskolaite and knorringite equilibrium with Cr2+ in a pure water system are very low. However, we found that complexes of Cr2+ and Cl- could increase the solubilities of chromium minerals significantly. At 500°C and 0.2 - 1.0 GPa, we retrieved the CrCl(OH)0 neutral complex from experiments on the solubility of Cr2O3 in HCl solutions [4]. At 1,000°C and 4.0 GPa, we retrieved the properties of a CrCl3- complex from experiments on the solubility of Cr2O3 in KCl solutions [5]. The predicted solubility of a garnet containing 23 mole% of knorringite in equilibrium with CrCl3- in a peridotitic diamond-forming fluid is 22 millimolal (1,144 ppm). This result suggests that a redox reaction relating to diamond formation might involveMg3Al2Si3O12 + 0.5CO2(aq) + 2 CrCl3- + 2H+ = Mg3Cr2Si3O12 + 0.5C-Diamond + 2Al3+ + 6Cl-. In this way, high temperature and pressure fluids containing Cr(II)-complexes might promote the mobility of chromium and be involved in metasomatic reactions and diamond formation.[1]Boyd et al. (1993)[2] Hao et al. (submitted to Geochem. Persp. Letters)[3] Berman (1988)[4] Klemme et al. (2000)[5] Klemme et al. (2004)[6] Watenphul et al. (2014)[7] Klein-BenDavid et al. (2011)

Multi-region approach to free-boundary three-dimensional tokamak equilibria and resistive wall instabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferraro, N. M.; Jardin, S. C.; Lao, L. L.

Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surround- ing vacuum region are included within the computational domain. Our implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition on the computational domain boundary and has the advantage of maintaining purely local coupling of mesh elements. We use this new capability to simulate perturbed, free-boundary non- axisymmetric equilibria; the linear evolution of resistive wall modes; and the linear andmore » nonlinear evolution of axisymmetric vertical displacement events (VDEs). Calculated growth rates for a resistive wall mode with arbitrary wall thickness are shown to agree well with the analytic theory. Equilibrium and VDE calculations are performed in diverted tokamak geometry, at physically real- istic values of dissipation, and with resistive walls of finite width. Simulations of a VDE disruption extend into the current-quench phase, in which the plasma becomes limited by the first wall, and strong currents are observed to flow in the wall, in the SOL, and from the plasma to the wall.« less

Multi-region approach to free-boundary three-dimensional tokamak equilibria and resistive wall instabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferraro, N. M., E-mail: nferraro@pppl.gov; Lao, L. L.; Jardin, S. C.

Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surrounding vacuum region are included within the computational domain. This implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition on the computational domain boundary and has the advantage of maintaining purely local coupling of mesh elements. This new capability is used to simulate perturbed, free-boundary non-axisymmetric equilibria; the linear evolution of resistive wall modes; and the linear and nonlinear evolutionmore » of axisymmetric vertical displacement events (VDEs). Calculated growth rates for a resistive wall mode with arbitrary wall thickness are shown to agree well with the analytic theory. Equilibrium and VDE calculations are performed in diverted tokamak geometry, at physically realistic values of dissipation, and with resistive walls of finite width. Simulations of a VDE disruption extend into the current-quench phase, in which the plasma becomes limited by the first wall, and strong currents are observed to flow in the wall, in the SOL, and from the plasma to the wall.« less

Multi-region approach to free-boundary three-dimensional tokamak equilibria and resistive wall instabilities

NASA Astrophysics Data System (ADS)

Ferraro, N. M.; Jardin, S. C.; Lao, L. L.; Shephard, M. S.; Zhang, F.

2016-05-01

Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surrounding vacuum region are included within the computational domain. This implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition on the computational domain boundary and has the advantage of maintaining purely local coupling of mesh elements. This new capability is used to simulate perturbed, free-boundary non-axisymmetric equilibria; the linear evolution of resistive wall modes; and the linear and nonlinear evolution of axisymmetric vertical displacement events (VDEs). Calculated growth rates for a resistive wall mode with arbitrary wall thickness are shown to agree well with the analytic theory. Equilibrium and VDE calculations are performed in diverted tokamak geometry, at physically realistic values of dissipation, and with resistive walls of finite width. Simulations of a VDE disruption extend into the current-quench phase, in which the plasma becomes limited by the first wall, and strong currents are observed to flow in the wall, in the SOL, and from the plasma to the wall.

Multi-region approach to free-boundary three-dimensional tokamak equilibria and resistive wall instabilities

DOE PAGES

Ferraro, N. M.; Jardin, S. C.; Lao, L. L.; ...

2016-05-20

Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surround- ing vacuum region are included within the computational domain. Our implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition on the computational domain boundary and has the advantage of maintaining purely local coupling of mesh elements. We use this new capability to simulate perturbed, free-boundary non- axisymmetric equilibria; the linear evolution of resistive wall modes; and the linear andmore » nonlinear evolution of axisymmetric vertical displacement events (VDEs). Calculated growth rates for a resistive wall mode with arbitrary wall thickness are shown to agree well with the analytic theory. Equilibrium and VDE calculations are performed in diverted tokamak geometry, at physically real- istic values of dissipation, and with resistive walls of finite width. Simulations of a VDE disruption extend into the current-quench phase, in which the plasma becomes limited by the first wall, and strong currents are observed to flow in the wall, in the SOL, and from the plasma to the wall.« less

Ideal Particle Sizes for Inhaled Steroids Targeting Vocal Granulomas: Preliminary Study Using Computational Fluid Dynamics.

PubMed

Perkins, Elizabeth L; Basu, Saikat; Garcia, Guilherme J M; Buckmire, Robert A; Shah, Rupali N; Kimbell, Julia S

2018-03-01

Objectives Vocal fold granulomas are benign lesions of the larynx commonly caused by gastroesophageal reflux, intubation, and phonotrauma. Current medical therapy includes inhaled corticosteroids to target inflammation that leads to granuloma formation. Particle sizes of commonly prescribed inhalers range over 1 to 4 µm. The study objective was to use computational fluid dynamics to investigate deposition patterns over a range of particle sizes of inhaled corticosteroids targeting the larynx and vocal fold granulomas. Study Design Retrospective, case-specific computational study. Setting Tertiary academic center. Subjects/Methods A 3-dimensional anatomically realistic computational model of a normal adult airway from mouth to trachea was constructed from 3 computed tomography scans. Virtual granulomas of varying sizes and positions along the vocal fold were incorporated into the base model. Assuming steady-state, inspiratory, turbulent airflow at 30 L/min, computational fluid dynamics was used to simulate respiratory transport and deposition of inhaled corticosteroid particles ranging over 1 to 20 µm. Results Laryngeal deposition in the base model peaked for particle sizes 8 to 10 µm (2.8%-3.5%). Ideal sizes ranged over 6 to 10, 7 to 13, and 7 to 14 µm for small, medium, and large granuloma sizes, respectively. Glottic deposition was maximal at 10.8% for 9-µm-sized particles for the large posterior granuloma, 3 times the normal model (3.5%). Conclusion As the virtual granuloma size increased and the location became more posterior, glottic deposition and ideal particle size generally increased. This preliminary study suggests that inhalers with larger particle sizes, such as fluticasone propionate dry-powder inhaler, may improve laryngeal drug deposition. Most commercially available inhalers have smaller particles than suggested here.

Computing Nash equilibria through computational intelligence methods

NASA Astrophysics Data System (ADS)

Pavlidis, N. G.; Parsopoulos, K. E.; Vrahatis, M. N.

2005-03-01

Nash equilibrium constitutes a central solution concept in game theory. The task of detecting the Nash equilibria of a finite strategic game remains a challenging problem up-to-date. This paper investigates the effectiveness of three computational intelligence techniques, namely, covariance matrix adaptation evolution strategies, particle swarm optimization, as well as, differential evolution, to compute Nash equilibria of finite strategic games, as global minima of a real-valued, nonnegative function. An issue of particular interest is to detect more than one Nash equilibria of a game. The performance of the considered computational intelligence methods on this problem is investigated using multistart and deflection.

Using a tracer technique to identify the extent of non-ideal flows in the continuous mixing of non-Newtonian fluids

NASA Astrophysics Data System (ADS)

Patel, D.; Ein-Mozaffari, F.; Mehrvar, M.

2013-05-01

The identification of non-ideal flows in a continuous-flow mixing of non-Newtonian fluids is a challenging task for various chemical industries: plastic manufacturing, water and wastewater treatment, and pulp and paper manufacturing. Non-ideal flows such as channelling, recirculation, and dead zones significantly affect the performance of continuous-flow mixing systems. Therefore, the main objective of this paper was to develop an identification protocol to measure non-ideal flows in the continuous-flow mixing system. The extent of non-ideal flows was quantified using a dynamic model that incorporated channelling, recirculation, and dead volume in the mixing vessel. To estimate the dynamic model parameters, the system was excited using a frequency-modulated random binary input by injecting the saline solution (as a tracer) into the fresh feed stream prior to being pumped into the mixing vessel. The injection of the tracer was controlled by a computer-controlled on-off solenoid valve. Using the trace technique, the extent of channelling and the effective mixed volume were successfully determined and used as mixing quality criteria. Such identification procedures can be applied at various areas of chemical engineering in order to improve the mixing quality.

Evaluation of Thermodynamic Models for Predicting Phase Equilibria of CO2 + Impurity Binary Mixture

NASA Astrophysics Data System (ADS)

Shin, Byeong Soo; Rho, Won Gu; You, Seong-Sik; Kang, Jeong Won; Lee, Chul Soo

2018-03-01

For the design and operation of CO2 capture and storage (CCS) processes, equation of state (EoS) models are used for phase equilibrium calculations. Reliability of an EoS model plays a crucial role, and many variations of EoS models have been reported and continue to be published. The prediction of phase equilibria for CO2 mixtures containing SO2, N2, NO, H2, O2, CH4, H2S, Ar, and H2O is important for CO2 transportation because the captured gas normally contains small amounts of impurities even though it is purified in advance. For the design of pipelines in deep sea or arctic conditions, flow assurance and safety are considered priority issues, and highly reliable calculations are required. In this work, predictive Soave-Redlich-Kwong, cubic plus association, Groupe Européen de Recherches Gazières (GERG-2008), perturbed-chain statistical associating fluid theory, and non-random lattice fluids hydrogen bond EoS models were compared regarding performance in calculating phase equilibria of CO2-impurity binary mixtures and with the collected literature data. No single EoS could cover the entire range of systems considered in this study. Weaknesses and strong points of each EoS model were analyzed, and recommendations are given as guidelines for safe design and operation of CCS processes.

Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Debabrata; Zhu, Ping; Maingi, Rajesh

Linear stability analysis of the national spherical torus experiment (NSTX) Li-conditioned ELM-free H-mode equilibria is carried out in the context of the extended magneto-hydrodynamic (MHD) model in NIMROD. Our purpose is to investigate the physical cause behind edge localized mode (ELM) suppression in experiment after the Li-coating of the divertor and the first wall of the NSTX tokamak. Besides ideal MHD modeling, including finite-Larmor radius effect and two-fluid Hall and electron diamagnetic drift contributions, a non-ideal resistivity model is employed, taking into account the increase of Z eff after Li-conditioning in ELM-free H-mode. And unlike an earlier conclusion from anmore » eigenvalue code analysis of these equilibria, NIMROD results find that after reduced recycling from divertor plates, profile modification is necessary but insufficient to explain the mechanism behind complete ELMs suppression in ideal two-fluid MHD. After considering the higher plasma resistivity due to higher Z eff, the complete stabilization could be explained. Furthermore, a thorough analysis of both pre-lithium ELMy and with-lithium ELM-free cases using ideal and non-ideal MHD models is presented, after accurately including a vacuum-like cold halo region in NIMROD to investigate ELMs.« less

Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX

DOE PAGES

Banerjee, Debabrata; Zhu, Ping; Maingi, Rajesh

2017-05-12

Linear stability analysis of the national spherical torus experiment (NSTX) Li-conditioned ELM-free H-mode equilibria is carried out in the context of the extended magneto-hydrodynamic (MHD) model in NIMROD. Our purpose is to investigate the physical cause behind edge localized mode (ELM) suppression in experiment after the Li-coating of the divertor and the first wall of the NSTX tokamak. Besides ideal MHD modeling, including finite-Larmor radius effect and two-fluid Hall and electron diamagnetic drift contributions, a non-ideal resistivity model is employed, taking into account the increase of Z eff after Li-conditioning in ELM-free H-mode. And unlike an earlier conclusion from anmore » eigenvalue code analysis of these equilibria, NIMROD results find that after reduced recycling from divertor plates, profile modification is necessary but insufficient to explain the mechanism behind complete ELMs suppression in ideal two-fluid MHD. After considering the higher plasma resistivity due to higher Z eff, the complete stabilization could be explained. Furthermore, a thorough analysis of both pre-lithium ELMy and with-lithium ELM-free cases using ideal and non-ideal MHD models is presented, after accurately including a vacuum-like cold halo region in NIMROD to investigate ELMs.« less

A Riccati solution for the ideal MHD plasma response with applications to real-time stability control

NASA Astrophysics Data System (ADS)

Glasser, Alexander; Kolemen, Egemen; Glasser, A. H.

2018-03-01

Active feedback control of ideal MHD stability in a tokamak requires rapid plasma stability analysis. Toward this end, we reformulate the δW stability method with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the generic tokamak ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD matrix Riccati differential equation. Since Riccati equations are prevalent in the control theory literature, such a shift in perspective brings to bear a range of numerical methods that are well-suited to the robust, fast solution of control problems. We discuss the usefulness of Riccati techniques in solving the stiff ordinary differential equations often encountered in ideal MHD stability analyses—for example, in tokamak edge and stellarator physics. We demonstrate the applicability of such methods to an existing 2D ideal MHD stability code—DCON [A. H. Glasser, Phys. Plasmas 23, 072505 (2016)]—enabling its parallel operation in near real-time, with wall-clock time ≪1 s . Such speed may help enable active feedback ideal MHD stability control, especially in tokamak plasmas whose ideal MHD equilibria evolve with inductive timescale τ≳ 1s—as in ITER.

First-principles Monte Carlo simulations of reaction equilibria in compressed vapors

DOE PAGES

Fetisov, Evgenii O.; Kuo, I-Feng William; Knight, Chris; ...

2016-06-13

Predictive modeling of reaction equilibria presents one of the grand challenges in the field of molecular simulation. Difficulties in the study of such systems arise from the need (i) to accurately model both strong, short-ranged interactions leading to the formation of chemical bonds and weak interactions arising from the environment, and (ii) to sample the range of time scales involving frequent molecular collisions, slow diffusion, and infrequent reactive events. Here we present a novel reactive first-principles Monte Carlo (RxFPMC) approach that allows for investigation of reaction equilibria without the need to prespecify a set of chemical reactions and their ideal-gasmore » equilibrium constants. We apply RxFPMC to investigate a nitrogen/oxygen mixture at T = 3000 K and p = 30 GPa, i.e., conditions that are present in atmospheric lightning strikes and explosions. The RxFPMC simulations show that the solvation environment leads to a significantly enhanced NO concentration that reaches a maximum when oxygen is present in slight excess. In addition, the RxFPMC simulations indicate the formation of NO 2 and N 2O in mole fractions approaching 1%, whereas N 3 and O 3 are not observed. Lastly, the equilibrium distributions obtained from the RxFPMC simulations agree well with those from a thermochemical computer code parametrized to experimental data.« less

First-principles Monte Carlo simulations of reaction equilibria in compressed vapors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fetisov, Evgenii O.; Kuo, I-Feng William; Knight, Chris

Predictive modeling of reaction equilibria presents one of the grand challenges in the field of molecular simulation. Difficulties in the study of such systems arise from the need (i) to accurately model both strong, short-ranged interactions leading to the formation of chemical bonds and weak interactions arising from the environment, and (ii) to sample the range of time scales involving frequent molecular collisions, slow diffusion, and infrequent reactive events. Here we present a novel reactive first-principles Monte Carlo (RxFPMC) approach that allows for investigation of reaction equilibria without the need to prespecify a set of chemical reactions and their ideal-gasmore » equilibrium constants. We apply RxFPMC to investigate a nitrogen/oxygen mixture at T = 3000 K and p = 30 GPa, i.e., conditions that are present in atmospheric lightning strikes and explosions. The RxFPMC simulations show that the solvation environment leads to a significantly enhanced NO concentration that reaches a maximum when oxygen is present in slight excess. In addition, the RxFPMC simulations indicate the formation of NO 2 and N 2O in mole fractions approaching 1%, whereas N 3 and O 3 are not observed. Lastly, the equilibrium distributions obtained from the RxFPMC simulations agree well with those from a thermochemical computer code parametrized to experimental data.« less

First-Principles Monte Carlo Simulations of Reaction Equilibria in Compressed Vapors

PubMed Central

2016-01-01

Predictive modeling of reaction equilibria presents one of the grand challenges in the field of molecular simulation. Difficulties in the study of such systems arise from the need (i) to accurately model both strong, short-ranged interactions leading to the formation of chemical bonds and weak interactions arising from the environment, and (ii) to sample the range of time scales involving frequent molecular collisions, slow diffusion, and infrequent reactive events. Here we present a novel reactive first-principles Monte Carlo (RxFPMC) approach that allows for investigation of reaction equilibria without the need to prespecify a set of chemical reactions and their ideal-gas equilibrium constants. We apply RxFPMC to investigate a nitrogen/oxygen mixture at T = 3000 K and p = 30 GPa, i.e., conditions that are present in atmospheric lightning strikes and explosions. The RxFPMC simulations show that the solvation environment leads to a significantly enhanced NO concentration that reaches a maximum when oxygen is present in slight excess. In addition, the RxFPMC simulations indicate the formation of NO2 and N2O in mole fractions approaching 1%, whereas N3 and O3 are not observed. The equilibrium distributions obtained from the RxFPMC simulations agree well with those from a thermochemical computer code parametrized to experimental data. PMID:27413785

On Nash-Equilibria of Approximation-Stable Games

NASA Astrophysics Data System (ADS)

Awasthi, Pranjal; Balcan, Maria-Florina; Blum, Avrim; Sheffet, Or; Vempala, Santosh

One reason for wanting to compute an (approximate) Nash equilibrium of a game is to predict how players will play. However, if the game has multiple equilibria that are far apart, or ɛ-equilibria that are far in variation distance from the true Nash equilibrium strategies, then this prediction may not be possible even in principle. Motivated by this consideration, in this paper we define the notion of games that are approximation stable, meaning that all ɛ-approximate equilibria are contained inside a small ball of radius Δ around a true equilibrium, and investigate a number of their properties. Many natural small games such as matching pennies and rock-paper-scissors are indeed approximation stable. We show furthermore there exist 2-player n-by-n approximation-stable games in which the Nash equilibrium and all approximate equilibria have support Ω(log n). On the other hand, we show all (ɛ,Δ) approximation-stable games must have an ɛ-equilibrium of support O(Δ^{2-o(1)}/ɛ2{log n}), yielding an immediate n^{O(Δ^{2-o(1)}/ɛ^2log n)}-time algorithm, improving over the bound of [11] for games satisfying this condition. We in addition give a polynomial-time algorithm for the case that Δ and ɛ are sufficiently close together. We also consider an inverse property, namely that all non-approximate equilibria are far from some true equilibrium, and give an efficient algorithm for games satisfying that condition.

Fast Numerical Solution of the Plasma Response Matrix for Real-time Ideal MHD Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glasser, Alexander; Kolemen, Egemen; Glasser, Alan H.

To help effectuate near real-time feedback control of ideal MHD instabilities in tokamak geometries, a parallelized version of A.H. Glasser’s DCON (Direct Criterion of Newcomb) code is developed. To motivate the numerical implementation, we first solve DCON’s δW formulation with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD Riccati equation. We then describe our adaptation of DCON with numerical methods natural to solutions of the Riccati equation, parallelizing it to enable its operation in near real-time. We replace DCON’s serial integration of perturbed modes—which satisfy a singular Euler- Lagrange equation—with a domain-decomposed integration of state transition matrices. Output is shown to match results from DCON with high accuracy, and with computation time < 1s. Such computational speed may enable active feedback ideal MHD stability control, especially in plasmas whose ideal MHD equilibria evolve with inductive timescalemore » $$\\tau$$ ≳ 1s—as in ITER. Further potential applications of this theory are discussed.« less

Fast Numerical Solution of the Plasma Response Matrix for Real-time Ideal MHD Control

DOE PAGES

Glasser, Alexander; Kolemen, Egemen; Glasser, Alan H.

2018-03-26

To help effectuate near real-time feedback control of ideal MHD instabilities in tokamak geometries, a parallelized version of A.H. Glasser’s DCON (Direct Criterion of Newcomb) code is developed. To motivate the numerical implementation, we first solve DCON’s δW formulation with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD Riccati equation. We then describe our adaptation of DCON with numerical methods natural to solutions of the Riccati equation, parallelizing it to enable its operation in near real-time. We replace DCON’s serial integration of perturbed modes—which satisfy a singular Euler- Lagrange equation—with a domain-decomposed integration of state transition matrices. Output is shown to match results from DCON with high accuracy, and with computation time < 1s. Such computational speed may enable active feedback ideal MHD stability control, especially in plasmas whose ideal MHD equilibria evolve with inductive timescalemore » $$\\tau$$ ≳ 1s—as in ITER. Further potential applications of this theory are discussed.« less

Hermite Polynomials and the Inverse Problem for Collisionless Equilibria

NASA Astrophysics Data System (ADS)

Allanson, O.; Neukirch, T.; Troscheit, S.; Wilson, F.

2017-12-01

It is long established that Hermite polynomial expansions in either velocity or momentum space can elegantly encode the non-Maxwellian velocity-space structure of a collisionless plasma distribution function (DF). In particular, Hermite polynomials in the canonical momenta naturally arise in the consideration of the 'inverse problem in collisionless equilibria' (IPCE): "for a given macroscopic/fluid equilibrium, what are the self-consistent Vlasov-Maxwell equilibrium DFs?". This question is of particular interest for the equilibrium and stability properties of a given macroscopic configuration, e.g. a current sheet. It can be relatively straightforward to construct a formal solution to IPCE by a Hermite expansion method, but several important questions remain regarding the use of this method. We present recent work that considers the necessary conditions of non-negativity, convergence, and the existence of all moments of an equilibrium DF solution found for IPCE. We also establish meaningful analogies between the equations that link the microscopic and macrosopic descriptions of the Vlasov-Maxwell equilibrium, and those that solve the initial value problem for the heat equation. In the language of the heat equation, IPCE poses the pressure tensor as the 'present' heat distribution over an infinite domain, and the non-Maxwellian features of the DF as the 'past' distribution. We find sufficient conditions for the convergence of the Hermite series representation of the DF, and prove that the non-negativity of the DF can be dependent on the magnetisation of the plasma. For DFs that decay at least as quickly as exp(-v^2/4), we show non-negativity is guaranteed for at least a finite range of magnetisation values, as parameterised by the ratio of the Larmor radius to the gradient length scale. 1. O. Allanson, T. Neukirch, S. Troscheit & F. Wilson: From one-dimensional fields to Vlasov equilibria: theory and application of Hermite polynomials, Journal of Plasma Physics, 82

Initial condition-dependent dynamics and transient period in memristor-based hypogenetic jerk system with four line equilibria

NASA Astrophysics Data System (ADS)

Bao, Han; Wang, Ning; Bao, Bocheng; Chen, Mo; Jin, Peipei; Wang, Guangyi

2018-04-01

Memristor-based nonlinear dynamical system easily presents the initial condition-dependent dynamical phenomenon of extreme multistability, i.e., coexisting infinitely many attractors, which has been received much attention in recent years. By introducing an ideal and active flux-controlled memristor into an existing hypogenetic chaotic jerk system, an interesting memristor-based chaotic system with hypogenetic jerk equation and circuit forms is proposed. The most striking feature is that this system has four line equilibria and exhibits the extreme multistability phenomenon of coexisting infinitely many attractors. Stability of these line equilibria are analyzed, and coexisting infinitely many attractors' behaviors with the variations of the initial conditions are investigated by bifurcation diagrams, Lyapunov exponent spectra, attraction basins, and phased portraits, upon which the forming mechanism of extreme multistablity in the memristor-based hypogenetic jerk system is explored. Specially, unusual transition behavior of long term transient period with steady chaos, completely different from the phenomenon of transient chaos, can be also found for some initial conditions. Moreover, a hardware circuit is design and fabricated and its experimental results effectively verify the truth of extreme multistablity.

Free-Boundary 3D Equilibria and Resistive Wall Instabilities with Extended-MHD

NASA Astrophysics Data System (ADS)

Ferraro, N. M.

2015-11-01

The interaction of the plasma with external currents, either imposed or induced, is a critical element of a wide range of important tokamak phenomena, including resistive wall mode (RWM) stability and feedback control, island penetration and locking, and disruptions. A model of these currents may be included within the domain of extended-MHD codes in a way that preserves the self-consistency, scalability, and implicitness of their numerical methods. Such a model of the resistive wall and non-axisymmetric coils is demonstrated using the M3D-C1 code for a variety of applications, including RWMs, perturbed non-axisymmetric equilibria, and a vertical displacement event (VDE) disruption. The calculated free-boundary equilibria, which include Spitzer resistivity, rotation, and two-fluid effects, are compared to external magnetic and internal thermal measurements for several DIII-D discharges. In calculations of the perturbed equilibria in ELM suppressed discharges, the tearing response at the top of the pedestal is found to correlate with the onset of ELM suppression. Nonlinear VDE calculations, initialized using a vertically unstable DIII-D equilibrium, resolve in both space and time the currents induced in the wall and on the plasma surface, and also the currents flowing between the plasma and the wall. The relative magnitude of these contributions and the total impulse to the wall depend on the resistive wall time, although the maximum axisymmetric force on the wall over the course of the VDE is found to be essentially independent of the wall conductivity. This research was supported by US DOE contracts DE-FG02-95ER54309, DE-FC02-04ER54698 and DE-AC52-07NA27344.

Use of reconstructed 3D VMEC equilibria to match effects of toroidally rotating discharges in DIII-D

DOE PAGES

Wingen, Andreas; Wilcox, Robert S.; Cianciosa, Mark R.; ...

2016-10-13

Here, a technique for tokamak equilibrium reconstructions is used for multiple DIII-D discharges, including L-mode and H-mode cases when weakly 3D fieldsmore » $$\\left(\\delta B/B\\sim {{10}^{-3}}\\right)$$ are applied. The technique couples diagnostics to the non-linear, ideal MHD equilibrium solver VMEC, using the V3FIT code, to find the most likely 3D equilibrium based on a suite of measurements. It is demonstrated that V3FIT can be used to find non-linear 3D equilibria that are consistent with experimental measurements of the plasma response to very weak 3D perturbations, as well as with 2D profile measurements. Observations at DIII-D show that plasma rotation larger than 20 krad s –1 changes the relative phase between the applied 3D fields and the measured plasma response. Discharges with low averaged rotation (10 krad s –1) and peaked rotation profiles (40 krad s –1) are reconstructed. Similarities and differences to forward modeled VMEC equilibria, which do not include rotational effects, are shown. Toroidal phase shifts of up to $${{30}^{\\circ}}$$ are found between the measured and forward modeled plasma responses at the highest values of rotation. The plasma response phases of reconstructed equilibra on the other hand match the measured ones. This is the first time V3FIT has been used to reconstruct weakly 3D tokamak equilibria.« less

Computational-hydrodynamic studies of the Noh compressible flow problem using non-ideal equations of state

NASA Astrophysics Data System (ADS)

Honnell, Kevin; Burnett, Sarah; Yorke, Chloe'; Howard, April; Ramsey, Scott

2017-06-01

The Noh problem is classic verification problem in the field of compressible flows. Simple to conceptualize, it is nonetheless difficult for numerical codes to predict correctly, making it an ideal code-verification test bed. In its original incarnation, the fluid is a simple ideal gas; once validated, however, these codes are often used to study highly non-ideal fluids and solids. In this work the classic Noh problem is extended beyond the commonly-studied polytropic ideal gas to more realistic equations of state (EOS) including the stiff gas, the Nobel-Abel gas, and the Carnahan-Starling hard-sphere fluid, thus enabling verification studies to be performed on more physically-realistic fluids. Exact solutions are compared with numerical results obtained from the Lagrangian hydrocode FLAG, developed at Los Alamos. For these more realistic EOSs, the simulation errors decreased in magnitude both at the origin and at the shock, but also spread more broadly about these points compared to the ideal EOS. The overall spatial convergence rate remained first order.

Amniotic fluid stem cells: an ideal resource for therapeutic application in bone tissue engineering.

PubMed

Pantalone, A; Antonucci, I; Guelfi, M; Pantalone, P; Usuelli, F G; Stuppia, L; Salini, V

2016-07-01

Skeletal diseases, both degenerative and secondary to trauma, infections or tumors, represent an ideal target for regenerative medicine and in the last years, stem cells have been considered as good candidates for in vitro and in vivo bone regeneration. To date, several stem cell sources, such as adult mesenchymal stem cells, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have shown significant osteogenic potential. In this narrative review, we analyze the possible advantages of the use of AFSCs in the treatment of skeletal diseases, especially through the application of tissue engineering and biomaterials. Among the different sources of stem cells, great attention has been recently devoted to amniotic fluid-derived stem cells (AFSC) characterized by high renewal capacity and ability to differentiate along several different lineages. Due to these features, AFSCs represent an interesting model for regenerative medicine, also considering their low immunogenicity and the absence of tumor formation after transplantation in nude mice.

Phase Equilibria and Crystallography of Ceramic Oxides

PubMed Central

Wong-Ng, W.; Roth, R. S.; Vanderah, T. A.; McMurdie, H. F.

2001-01-01

Research in phase equilibria and crystallography has been a tradition in the Ceramics Division at National Bureau of Standards/National Institute of Standatrds and Technology (NBS/NIST) since the early thirties. In the early years, effort was concentrated in areas of Portland cement, ceramic glazes and glasses, instrument bearings, and battery materials. In the past 40 years, a large portion of the work was related to electronic materials, including ferroelectrics, piezoelectrics, ionic conductors, dielectrics, microwave dielectrics, and high-temperature superconductors. As a result of the phase equilibria studies, many new compounds have been discovered. Some of these discoveries have had a significant impact on US industry. Structure determinations of these new phases have often been carried out as a joint effort among NBS/NIST colleagues and also with outside collaborators using both single crystal and neutron and x-ray powder diffraction techniques. All phase equilibria diagrams were included in Phase Diagrams for Ceramists, which are collaborative publications between The American Ceramic Society (ACerS) and NBS/NIST. All x-ray powder diffraction patterns have been included in the Powder Diffraction File (PDF). This article gives a brief account of the history of the development of the phase equilibria and crystallographic research on ceramic oxides in the Ceramics Division. Represented systems, particularly electronic materials, are highlighted. PMID:27500068

Estimating Values of H2O-ACTIVITIES in the Mantle Using Amphibole Equilibria

NASA Astrophysics Data System (ADS)

Lamb, W. M.; Hunt, L. E.

2017-12-01

Determining values of H2O activity (aH2O) for mantle rocks will yield a better understanding of those mantle processes that are controlled, in part, by the availability of H2O (e.g., melting and deformation). The H contents of the upper mantle can be estimated from amount of H contained in nominally anhydrous minerals (NAMs). However, for many common NAMs, the relation between aH2O and H content is not well known, and certain NAMs may be prone to retrograde H loss. The activities of H2O and other fluids species (e.g., CO2) may be estimated using mineral equilibria. Equilibria involving amphibole can, for example, be used to estimate values of aH2O and hydrogen fugacity (ƒH2). Spinel equilibria can be applied to estimate values of oxygen fugacity (ƒO2) that, when combined with ƒH2, will provide a second estimate of aH2O. We have characterized mineral chemistries in 11 amphibole-bearing peridotite xenoliths from the southwestern U.S.A. The compositions of co-existing pyroxenes ± garnet yield P-T conditions of ≈ 1.1 GPa, and 880 to 980˚C, and application of dehydration equilibria yields values of aH2O ranging from 0.04 to 0.19. The compositions of coexisting spinel + olivine + opx yield DlogƒO2(FMQ) of -0.2 to +0.9. Values of ƒH2, estimated using amphibole dehydrogenation equilibria (6 to 91 bars) were combined with values of ƒO2 to estimate aH2O in nine samples (≈ 0.02 to 0.12). The difference between these two values of aH2O, estimated using dehydration equilibria versus ƒH2 + ƒO2, is generally < 0.1, suggesting that the amphiboles experienced little or no retrograde H-loss. All samples equilibrated at low values of aH2O, and these values may be used to predict NAM H-contents. For example, according to Gaetani et al. (2014, Cont. Min. Pet., p. 965), the concentration of H in olivine is a function of P, T, the fugacities of H2O and O2, and olivine composition. Their relation yields relatively low predicted H-contents of 10 to 28 wt. ppm for olivine in

The stability analysis of magnetohydrodynamic equilibria - Comparing the thermodynamic approach with the energy principle

NASA Technical Reports Server (NTRS)

Brinkmann, R. P.

1989-01-01

This paper is a contribution to the stability analysis of current-carrying plasmas, i.e., plasma systems that are forced by external mchanisms to carry a nonrelaxing electrical current. Under restriction to translationally invariant configurations, the thermodynamic stability criterion for a multicomponent plasma is rederived within the framework of nonideal MHD. The chosen dynamics neglects scalar resistivity, but allows for other types of dissipation effects both in Ohm's law and in the equation of motion. In the second section of the paper, the thermodynamic stability criterion is compared with the ideal MHD based energy principle of Bernstein et al. With the help of Schwarz's inequality, it is shown that the former criterion is always more 'pessimistic' than the latter, i.e., that thermodynamic stability implies stability according to the MHD principle, but not vice versa. This reuslt confirms the physical plausible idea that dissipational effects tend to weaken the stability properties of current-carrying plasma equilibria by breaking the constraints of ideal MHD and allowing for possibly destabilizing effects such as magnetic field line reconfiguration.

Ca-Rich Carbonate Melts: A Regular-Solution Model, with Applications to Carbonatite Magma + Vapor Equilibria and Carbonate Lavas on Venus

NASA Technical Reports Server (NTRS)

Treiman, Allan H.

1995-01-01

A thermochemical model of the activities of species in carbonate-rich melts would be useful in quantifying chemical equilibria between carbonatite magmas and vapors and in extrapolating liquidus equilibria to unexplored PTX. A regular-solution model of Ca-rich carbonate melts is developed here, using the fact that they are ionic liquids, and can be treated (to a first approximation) as interpenetrating regular solutions of cations and of anions. Thermochemical data on systems of alkali metal cations with carbonate and other anions are drawn from the literature; data on systems with alkaline earth (and other) cations and carbonate (and other) anions are derived here from liquidus phase equilibria. The model is validated in that all available data (at 1 kbar) are consistent with single values for the melting temperature and heat of fusion for calcite, and all liquidi are consistent with the liquids acting as regular solutions. At 1 kbar, the metastable congruent melting temperature of calcite (CaCO3) is inferred to be 1596 K, with (Delta)bar-H(sub fus)(calcite) = 31.5 +/- 1 kJ/mol. Regular solution interaction parameters (W) for Ca(2+) and alkali metal cations are in the range -3 to -12 kJ/sq mol; W for Ca(2+)-Ba(2+) is approximately -11 kJ/sq mol; W for Ca(2+)-Mg(2+) is approximately -40 kJ/sq mol, and W for Ca(2+)-La(3+) is approximately +85 kJ/sq mol. Solutions of carbonate and most anions (including OH(-), F(-), and SO4(2-)) are nearly ideal, with W between 0(ideal) and -2.5 kJ/sq mol. The interaction of carbonate and phosphate ions is strongly nonideal, which is consistent with the suggestion of carbonate-phosphate liquid immiscibility. Interaction of carbonate and sulfide ions is also nonideal and suggestive of carbonate-sulfide liquid immiscibility. Solution of H2O, for all but the most H2O-rich compositions, can be modeled as a disproportionation to hydronium (H3O(+)) and hydroxyl (OH(-)) ions with W for Ca(2+)-H3O(+) (approximately) equals 33 kJ/sq mol. The

A generalized procedure for the prediction of multicomponent adsorption equilibria

DOE PAGES

Ladshaw, Austin; Yiacoumi, Sotira; Tsouris, Costas

2015-04-07

Prediction of multicomponent adsorption equilibria has been investigated for several decades. While there are theories available to predict the adsorption behavior of ideal mixtures, there are few purely predictive theories to account for nonidealities in real systems. Most models available for dealing with nonidealities contain interaction parameters that must be obtained through correlation with binary-mixture data. However, as the number of components in a system grows, the number of parameters needed to be obtained increases exponentially. Here, a generalized procedure is proposed, as an extension of the predictive real adsorbed solution theory, for determining the parameters of any activity model,more » for any number of components, without correlation. This procedure is then combined with the adsorbed solution theory to predict the adsorption behavior of mixtures. As this method can be applied to any isotherm model and any activity model, it is referred to as the generalized predictive adsorbed solution theory.« less

Hall effect on magnetohydrodynamic instabilities at an elliptic magnetic stagnation line

NASA Astrophysics Data System (ADS)

Spies, Günther O.; Faghihi, Mustafa

1987-06-01

To answer the question whether the Hall effect removes the unphysical feature of ideal magnetohydrodynamics of predicting small wavelength kink instabilities at any elliptic magnetic stagnation line, a normal mode analysis is performed of the motion of an incompressible Hall fluid about cylindrical Z-pinch equilibria with circular cross sections. The eigenvalue loci in the complex frequency plane are derived for the equilibrium with constant current density. Every particular mode becomes stable as the Hall parameter exceeds a critical value. This value, however, depends on the mode such that it increases to infinity as the ideal growth rate decreases to zero, implying that there always remains an infinite number of slowly growing instabilities. Correspondingly, the stability criterion for equilibria with arbitrary current distributions is independent of the Hall parameter.

Relative equilibria in quasi-homogeneous planar three body problems

NASA Astrophysics Data System (ADS)

Arredondo, John A.

2018-01-01

In this paper we find the families of relative equilibria for the three body problem in the plane, when the interaction between the bodies is given by a quasi-homogeneous potential. The number of the relative equilibria depends on the values of the masses and on the size of the system, measured by the moment of inertia.

Equilibria of oligomeric proteins under high pressure - A theoretical description.

PubMed

Ingr, Marek; Kutálková, Eva; Hrnčiřík, Josef; Lange, Reinhard

2016-12-21

High pressure methods have become a useful tool for studying protein structure and stability. Using them, various physico-chemical processes including protein unfolding, aggregation, oligomer dissociation or enzyme-activity decrease were studied on many different proteins. Oligomeric protein dissociation is a process that can perfectly utilize the potential of high-pressure techniques, as the high pressure shifts the equilibria to higher concentrations making them better observable by spectroscopic methods. This can be especially useful when the oligomeric form is highly stable at atmospheric pressure. These applications may be, however, hindered by less intensive experimental response as well as interference of the oligomerization equilibria with unfolding or aggregation of the subunits, but also by more complex theoretical description. In this study we develop mathematical models describing different kinds of oligomerization equilibria, both closed (equilibrium of monomer and the highest possible oligomer without any intermediates) and consecutive. Closed homooligomer equilibria are discussed for any oligomerization degree, while the more complex heterooligomer equilibria and the consecutive equilibria in both homo- and heterooligomers are taken into account only for dimers and trimers. In all the cases, fractions of all the relevant forms are evaluated as functions of pressure and concentration. Significant points (inflection points and extremes) of the resulting transition curves, that can be determined experimentally, are evaluated as functions of pressure and/or concentration. These functions can be further used in order to evaluate the thermodynamic parameters of the system, i.e. atmospheric-pressure equilibrium constants and volume changes of the individual steps of the oligomer-dissociation processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ideal heat transfer conditions for tubular solar receivers with different design constraints

NASA Astrophysics Data System (ADS)

Kim, Jin-Soo; Potter, Daniel; Gardner, Wilson; Too, Yen Chean Soo; Padilla, Ricardo Vasquez

2017-06-01

The optimum heat transfer condition for a tubular type solar receiver was investigated for various receiver pipe size, heat transfer fluid, and design requirement and constraint(s). Heat transfer of a single plain receiver pipe exposed to concentrated solar energy was modelled along the flow path of the heat transfer fluid. Three different working fluids, molten salt, sodium, and supercritical carbon dioxide (sCO2) were considered in the case studies with different design conditions. The optimized ideal heat transfer condition was identified through fast iterative heat transfer calculations solving for all relevant radiation, conduction and convection heat transfers throughout the entire discretized tubular receiver. The ideal condition giving the best performance was obtained by finding the highest acceptable solar energy flux optimally distributed to meet different constraint(s), such as maximum allowable material temperature of receiver, maximum allowable film temperature of heat transfer fluid, and maximum allowable stress of receiver pipe material. The level of fluid side turbulence (represented by pressure drop in this study) was also optimized to give the highest net power production. As the outcome of the study gives information on the most ideal heat transfer condition, it can be used as a useful guideline for optimal design of a real receiver and solar field in a combined manner. The ideal heat transfer condition is especially important for high temperature tubular receivers (e.g. for supplying heat to high efficiency Brayton cycle turbines) where the system design and performance is tightly constrained by the receiver pipe material strength.

Theoretical features of MHD equilibria with flow

NASA Astrophysics Data System (ADS)

Beklemishev, Alexei; Tessarotto, Massimo

2002-11-01

The effect produced on plasma dynamics by plasma flows, especially those produced by strong E× B-drifts represent an important theoretical issue in magnetic confinement. These include in particular Stellarator equilibria in the presence of weak flows, with velocity much smaller in magnitude than the ion thermal velocity [1]. Strong flows, however, more generally can be produced locally in a variety of physical situations (for example due to strong radial electric fields, neutral beams, RF heating, etc.). These flows can be important in establishing advanced operational regimes, such as the recently discovered HDH mode in the W7-AS Stellarator [2]. Goal of this work is to investigate theoretical features of the MHD equilibria in the presence of strong flows, with particular reference to conditions of existence of kinetic equilibria, particle adiabatic and/or bounce-averaged invariants. References 1 - M. Tessarotto, J.L. Johnson, R.B. White and L.J. Zheng, Phys. Plasmas 3, 2653 (1996); 2 - K. McCormick et al., Phys. Rev. Lett. 89, 15001 (2002).

PIES free boundary stellarator equilibria with improved initial conditions

NASA Astrophysics Data System (ADS)

Drevlak, M.; Monticello, D.; Reiman, A.

2005-07-01

The MFBE procedure developed by Strumberger (1997 Nucl. Fusion 37 19) is used to provide an improved starting point for free boundary equilibrium computations in the case of W7-X (Nührenberg and Zille 1986 Phys. Lett. A 114 129) using the Princeton iterative equilibrium solver (PIES) code (Reiman and Greenside 1986 Comput. Phys. Commun. 43 157). Transferring the consistent field found by the variational moments equilibrium code (VMEC) (Hirshmann and Whitson 1983 Phys. Fluids 26 3553) to an extended coordinate system using the VMORPH code, a safe margin between plasma boundary and PIES domain is established. The new EXTENDER_P code implements a generalization of the virtual casing principle, which allows field extension both for VMEC and PIES equilibria. This facilitates analysis of the 5/5 islands of the W7-X standard case without including them in the original PIES computation.

Ideal glass transitions in thin films: An energy landscape perspective

NASA Astrophysics Data System (ADS)

Truskett, Thomas M.; Ganesan, Venkat

2003-07-01

We introduce a mean-field model for the potential energy landscape of a thin fluid film confined between parallel substrates. The model predicts how the number of accessible basins on the energy landscape and, consequently, the film's ideal glass transition temperature depend on bulk pressure, film thickness, and the strength of the fluid-fluid and fluid-substrate interactions. The predictions are in qualitative agreement with the experimental trends for the kinetic glass transition temperature of thin films, suggesting the utility of landscape-based approaches for studying the behavior of confined fluids.

Creation of an idealized nasopharynx geometry for accurate computational fluid dynamics simulations of nasal airflow in patient-specific models lacking the nasopharynx anatomy

PubMed Central

Borojeni, Azadeh A.T.; Frank-Ito, Dennis O.; Kimbell, Julia S.; Rhee, John S.; Garcia, Guilherme J. M.

2016-01-01

Virtual surgery planning based on computational fluid dynamics (CFD) simulations has the potential to improve surgical outcomes for nasal airway obstruction (NAO) patients, but the benefits of virtual surgery planning must outweigh the risks of radiation exposure. Cone beam computed tomography (CBCT) scans represent an attractive imaging modality for virtual surgery planning due to lower costs and lower radiation exposures compared with conventional CT scans. However, to minimize the radiation exposure, the CBCT sinusitis protocol sometimes images only the nasal cavity, excluding the nasopharynx. The goal of this study was to develop an idealized nasopharynx geometry for accurate representation of outlet boundary conditions when the nasopharynx geometry is unavailable. Anatomically-accurate models of the nasopharynx created from thirty CT scans were intersected with planes rotated at different angles to obtain an average geometry. Cross sections of the idealized nasopharynx were approximated as ellipses with cross-sectional areas and aspect ratios equal to the average in the actual patient-specific models. CFD simulations were performed to investigate whether nasal airflow patterns were affected when the CT-based nasopharynx was replaced by the idealized nasopharynx in 10 NAO patients. Despite the simple form of the idealized geometry, all biophysical variables (nasal resistance, airflow rate, and heat fluxes) were very similar in the idealized vs. patient-specific models. The results confirmed the expectation that the nasopharynx geometry has a minimal effect in the nasal airflow patterns during inspiration. The idealized nasopharynx geometry will be useful in future CFD studies of nasal airflow based on medical images that exclude the nasopharynx. PMID:27525807

Dynamics of Vortex and Magnetic Lines in Ideal Hydrodynamics and MHD

NASA Astrophysics Data System (ADS)

Kuznetsov, E. A.; Ruban, V. P.

Vortex line and magnetic line representations are introduced for description of flows in ideal hydrodynamics and MHD, respectively. For incompressible fluids it is shown that the equations of motion for vorticity φ and magnetic field with the help of this transformation follow from the variational principle. By means of this representation it is possible to integrate the system of hydrodynamic type with the Hamiltonian H=|φ|dr. It is also demonstrated that these representations allow to remove from the noncanonical Poisson brackets, defined on the space of divergence-free vector fields, degeneracy connected with the vorticity frozenness for the Euler equation and with magnetic field frozenness for ideal MHD. For MHD a new Weber type transformation is found. It is shown how this transformation can be obtained from the two-fluid model when electrons and ions can be considered as two independent fluids. The Weber type transformation for ideal MHD gives the whole Lagrangian vector invariant. When this invariant is absent this transformation coincides with the Clebsch representation analog introduced in [1].

Discovering the Thermodynamics of Simultaneous Equilibria: An Entropy Analysis Activity Involving Consecutive Equilibria

ERIC Educational Resources Information Center

Bindel, Thomas H.

2007-01-01

An activity is presented in which the thermodynamics of simultaneous, consecutive equilibria are explored. The activity is appropriate for second-year high school or AP chemistry. Students discover that a reactant-favored (entropy-diminishing or endergonic) reaction can be caused to happen if it is coupled with a product-favored reaction of…

Nanopore Confinement of C-O-H Fluids Relevant to Subsurface Energy Systems

NASA Astrophysics Data System (ADS)

Cole, D. R.

2016-12-01

Complex intermolecular interactions of C-O-H fluids (e.g., H2O, CO2, CH4) result in their unique thermophysical properties, including large deviations in the volumetric properties from ideality, vapor-liquid equilibria, and critical phenomena as these fluids encounter different pressure-temperature-pore network conditions in the crust. Development of a comprehensive understanding of the structures, dynamics, and reactivity at multiple length scales (molecular to macroscopic) over wide ranges of state conditions and composition is foundational to advances in quantifying geochemical processes involving mineral-fluid interfaces. The size, distribution and connectivity of these confined geometries dictate how fluids migrate into and through these micro- and nano-environments, wet and react with the solid. This presentation will provide an overview of the application of state-of-the-art experimental, analytical and computational tools to assess key features of the fluid-matrix interaction. The multidisciplinary approaches highlighted will include neutron scattering and NMR experiments, thermodynamic measurements and molecular-level simulations to quantitatively assess molecular properties of different mixtures of C-O-H fluids in nanpores. Key results include: (1) The addition of a second carbon-bearing phase or water has a profound effect on the competition for sorption sites, phase chemistry and the dynamical properties of all phases present in the pore. (2) Low solubility phases such as methane may exhibit profound increases in concentration in nanopores in the presence of water at elevated pressures and ambient temperature compared to bulk values. (3) Methane permeability through the hydrated pores is strongly dependent on the solid substrate and local properties of confined water, including its structure and, more importantly, evolution of solvation free energy and hydrogen bond structure. (4) Under certain conditions preferential adsorption of the fluids in the

Effects of real fluid properties on axial turbine meanline design and off-design analysis

NASA Astrophysics Data System (ADS)

MacLean, Cameron

The effects of real fluid properties on axial turbine meanline analysis have been investigated employing two meanline analysis codes, namely Turbine Meanline Design (TMLD) and Turbine Meanline Off-Design (TMLO). The previously developed TMLD code assumed the working fluid was an ideal gas. Therefore it was modified to use real fluid properties. TMLO was then developed from TMLD Both codes can be run using either the ideal gas assumption or real fluid properties. TMLD was employed for the meanline design of several axial turbines for a range of inlet conditions, using both the ideal gas assumption and real fluid properties. The resulting designs were compared to see the effects of real fluid properties. Meanline designs, generated using the ideal gas assumption, were then analysed with TMLO using real fluid properties. This was done over a range of inlet conditions that correspond to varying degrees of departure from ideal gas conditions. The goal was to show how machines designed with the ideal gas assumption would perform with the real working fluid. The working fluid used in both investigations was supercritical carbon dioxide. Results from the investigation show that real fluid properties had a strong effect on the gas path areas of the turbine designs as well as the performance of turbines designed using the ideal gas assumption. Specifically, power output and the velocities of the working fluid were affected. It was found that accounting for losses tended to lessen the effects of the real fluid properties.

Counterexamples to Moffatt's statements on vortex knots.

PubMed

Bogoyavlenskij, Oleg

2017-04-01

One of the well-known problems of hydrodynamics is studied: the problem of classification of vortex knots for ideal fluid flows. In the literature there are known Moffatt statements that all torus knots K_{m,n} for all rational numbers m/n (0fluid flows. We prove that actually such a uniformity does not exist because it does not correspond to the facts. Namely, we derive a complete classification of all vortex knots realized for the fluid flows studied by Moffatt and demonstrate that the real structure of vortex knots is much more rich because the sets of mutually nonisotopic vortex knots realized for different axisymmetric fluid flows are all different. An exact formula for the limit of the hydrodynamic safety factor q_{h} at a vortex axis is derived for arbitrary axisymmetric fluid equilibria. Another exact formula is obtained for the limit of the magnetohydrodynamics safety factor q at a magnetic axis for the general axisymmetric plasma equilibria.

Selective adsorption and phase equilibria of confined fluids: Density-functional theory and Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Sowers, Susanne Lynn

1997-11-01

Microporous sorbents such as carbons, silicas and aluminas are used commercially in a variety of separation, purification and selective reaction applications. A detailed study of the effects of the porous material characteristics on the adsorption equilibrium properties such as selectivity and phase equilibria of fluid mixtures can enhance our understanding of adsorption on a molecular level. Such knowledge will improve our utilization of such adsorbents and provide a tool for directing the future of tailoring sorbents for particular separation processes. The effect of pore size, shape and pressure on the selective adsorption of trace pollutants from an inert gas was studied using prototype mixtures of Lennard-Tones (LJ) N2/CCl4, CF4, and SO2. Both nonlocal density functional theory (DFT) and grand canonical Monte Carlo (GCMC) molecular simulations were used in order to investigate the validity of the theory, which is much quicker and easier to use. Our results indicate that there is an optimal pore size and shape for which the pollutant selectivity is greatly enhanced. In many industrial adsorption processes relative humidity can greatly affect the life of an adsorbent bed, as seen in breakthrough curves. Therefore, the influence of water vapor on the selective adsorption of CCl4 from a mixture of N2/CCl4/H20 in activated carbon was studied using GCMC simulations. The equilibrium adsorption properties are found to be dependent upon both the density of active sites on the pore walls and the relative humidity. Liquid-liquid transitions in porous materials are of interest in connection with oil recovery, lubrication, coating technology and pollution control. The results of a study on the effect of confinement on the liquid-liquid equilibrium of binary LJ mixtures using DFT are compared with those of molecular simulation and experiments. Our findings show that the phase coexistence for the confined mixture is in general decreased and shifted toward the component which

Quantum Nash Equilibria and Quantum Computing

NASA Astrophysics Data System (ADS)

Fellman, Philip Vos; Post, Jonathan Vos

In 2004, At the Fifth International Conference on Complex Systems, we drew attention to some remarkable findings by researchers at the Santa Fe Institute (Sato, Farmer and Akiyama, 2001) about hitherto unsuspected complexity in the Nash Equilibrium. As we progressed from these findings about heteroclinic Hamiltonians and chaotic transients hidden within the learning patterns of the simple rock-paper-scissors game to some related findings on the theory of quantum computing, one of the arguments we put forward was just as in the late 1990's a number of new Nash equilibria were discovered in simple bi-matrix games (Shubik and Quint, 1996; Von Stengel, 1997, 2000; and McLennan and Park, 1999) we would begin to see new Nash equilibria discovered as the result of quantum computation. While actual quantum computers remain rather primitive (Toibman, 2004), and the theory of quantum computation seems to be advancing perhaps a bit more slowly than originally expected, there have, nonetheless, been a number of advances in computation and some more radical advances in an allied field, quantum game theory (Huberman and Hogg, 2004) which are quite significant. In the course of this paper we will review a few of these discoveries and illustrate some of the characteristics of these new "Quantum Nash Equilibria". The full text of this research can be found at http://necsi.org/events/iccs6/viewpaper.php?id-234

CRYOCHEM, Thermodynamic Model for Cryogenic Chemical Systems: Solid-Vapor and Solid-Liquid-Vapor Phase Equilibria Toward Applications on Titan and Pluto

NASA Astrophysics Data System (ADS)

Tan, S. P.; Kargel, J. S.; Adidharma, H.; Marion, G. M.

2014-12-01

Until in-situ measurements can be made regularly on extraterrestrial bodies, thermodynamic models are the only tools to investigate the properties and behavior of chemical systems on those bodies. The resulting findings are often critical in describing physicochemical processes in the atmosphere, surface, and subsurface in planetary geochemistry and climate studies. The extremely cold conditions on Triton, Pluto and other Kuiper Belt Objects, and Titan introduce huge non-ideality that prevents conventional models from performing adequately. At such conditions, atmospheres as a whole—not components individually—are subject to phase equilibria with their equilibrium solid phases or liquid phases or both. A molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, the development of which is still in progress, was shown to reproduce the vertical composition profile of Titan's atmospheric methane measured by the Huygens probe (Tan et al., Icarus 2013, 222, 53). Recently, the model was also used to describe Titan's global circulation where the calculated composition of liquid in Ligeia Mare is consistent with the bathymetry and microwave absorption analysis of T91 Cassini fly-by data (Tan et al., 2014, submitted). Its capability to deal with equilibria involving solid phases has also been demonstrated (Tan et al., Fluid Phase Equilib. 2013, 360, 320). With all those previous works done, our attention is now shifting to the lower temperatures in Titan's tropopause and on Pluto's surface, where much technical development remains for CRYOCHEM to assure adequate performance at low temperatures. In these conditions, solid-vapor equilibrium (SVE) is the dominant phase behavior that determines the composition of the atmosphere and the existing ices. Another potential application is for the subsurface phase equilibrium, which also involves liquid, thus three-phase equilibrium: solid-liquid-vapor (SLV). This presentation will discuss the

Vapor-liquid equilibria for hydrogen fluoride + 1,1-difluoroethane at 288.23 and 298.35 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J.; Kim, H.; Lim, J.S.

1997-07-01

Isothermal vapor-liquid equilibria for hydrogen fluoride + 1,1-difluoroethane at 288.23 and 298.35 K were measured using a circulation type apparatus equipped with an equilibrium view cell. The compositions of both vapor and liquid phases were analyzed by an on-line gas chromatographic method. They were compared with PTx equilibrium data measured by the total pressure method. The experimental data were correlated with Anderko`s equation of state using the Wong-Sandler mixing rule as well as the van der Waals one-fluid mixing rule. The Wong-Sandler mixing rule gives better results, and the relevant parameters are presented.

Correct Representation of Conformational Equilibria.

ERIC Educational Resources Information Center

Fulop, F.; And Others

1983-01-01

In representing conformational equilibria of compounds having only one chiral center, erroneous formulas showing different antipodes on the two sides of the equilibrium are rare. In contrast, with compounds having two or more chiral centers especially with saturated heterocycles, this erroneous representation occurs frequently in the chemical…

Catenaries in viscous fluid

NASA Astrophysics Data System (ADS)

Hanna, James; Chakrabarti, Brato

2015-11-01

Slender structures live in fluid flows across many scales, from towed instruments to plant blades to microfluidic valves. The present work details a simple model of a flexible structure in a uniform flow. We present analytical solutions for the translating, axially flowing equilibria of strings subjected to a uniform body force and linear drag forces. This is an extension of the classical catenaries to a five-parameter family of solutions, represented as trajectories in angle-curvature ``phase space.'' Limiting cases include neutrally buoyant towed cables and freely sedimenting flexible filaments. Now at University of California, San Diego.

Mixed Nash equilibria in Eisert-Lewenstein-Wilkens (ELW) games

NASA Astrophysics Data System (ADS)

Bolonek-Lasoń, Katarzyna; Kosiński, Piotr

2017-01-01

The classification of all mixed Nash equilibria for the original ELW game is presented. It is based on the quaternionic form of the game proposed by Landsburg (Proc. Am. Math. Soc. 139 (2011), 4423; Rochester Working Paper No 524 (2006); Wiley Encyclopedia of Operations Research and Management Science (Wiley and Sons, New York, (2011)). This approach allows to reduce the problem of finding the Nash equilibria to relatively simple analysis of the extrema of certain quadratic forms.

Morse Theory and Relative Equilibria in the Planar n-Vortex Problem

NASA Astrophysics Data System (ADS)

Roberts, Gareth E.

2018-04-01

Morse theoretical ideas are applied to the study of relative equilibria in the planar n-vortex problem. For the case of positive circulations, we prove that the Morse index of a critical point of the Hamiltonian restricted to a level surface of the angular impulse is equal to the number of pairs of real eigenvalues of the corresponding relative equilibrium periodic solution. The Morse inequalities are then used to prove the instability of some families of relative equilibria in the four-vortex problem with two pairs of equal vorticities. We also show that, for positive circulations, relative equilibria cannot accumulate on the collision set.

The Statistical Mechanics of Ideal MHD Turbulence

NASA Technical Reports Server (NTRS)

Shebalin, John V.

2003-01-01

Turbulence is a universal, nonlinear phenomenon found in all energetic fluid and plasma motion. In particular. understanding magneto hydrodynamic (MHD) turbulence and incorporating its effects in the computation and prediction of the flow of ionized gases in space, for example, are great challenges that must be met if such computations and predictions are to be meaningful. Although a general solution to the "problem of turbulence" does not exist in closed form, numerical integrations allow us to explore the phase space of solutions for both ideal and dissipative flows. For homogeneous, incompressible turbulence, Fourier methods are appropriate, and phase space is defined by the Fourier coefficients of the physical fields. In the case of ideal MHD flows, a fairly robust statistical mechanics has been developed, in which the symmetry and ergodic properties of phase space is understood. A discussion of these properties will illuminate our principal discovery: Coherent structure and randomness co-exist in ideal MHD turbulence. For dissipative flows, as opposed to ideal flows, progress beyond the dimensional analysis of Kolmogorov has been difficult. Here, some possible future directions that draw on the ideal results will also be discussed. Our conclusion will be that while ideal turbulence is now well understood, real turbulence still presents great challenges.

Pancreatic fluid collections: What is the ideal imaging technique?

PubMed

Dhaka, Narendra; Samanta, Jayanta; Kochhar, Suman; Kalra, Navin; Appasani, Sreekanth; Manrai, Manish; Kochhar, Rakesh

2015-12-28

Pancreatic fluid collections (PFCs) are seen in up to 50% of cases of acute pancreatitis. The Revised Atlanta classification categorized these collections on the basis of duration of disease and contents, whether liquid alone or a mixture of fluid and necrotic debris. Management of these different types of collections differs because of the variable quantity of debris; while patients with pseudocysts can be drained by straight-forward stent placement, walled-off necrosis requires multi-disciplinary approach. Differentiating these collections on the basis of clinical severity alone is not reliable, so imaging is primarily performed. Contrast-enhanced computed tomography is the commonly used modality for the diagnosis and assessment of proportion of solid contents in PFCs; however with certain limitations such as use of iodinated contrast material especially in renal failure patients and radiation exposure. Magnetic resonance imaging (MRI) performs better than computed tomography (CT) in characterization of pancreatic/peripancreatic fluid collections especially for quantification of solid debris and fat necrosis (seen as fat density globules), and is an alternative in those situations where CT is contraindicated. Also magnetic resonance cholangiopancreatography is highly sensitive for detecting pancreatic duct disruption and choledocholithiasis. Endoscopic ultrasound is an evolving technique with higher reproducibility for fluid-to-debris component estimation with the added advantage of being a single stage procedure for both diagnosis (solid debris delineation) and management (drainage of collection) in the same sitting. Recently role of diffusion weighted MRI and positron emission tomography/CT with (18)F-FDG labeled autologous leukocytes is also emerging for detection of infection noninvasively. Comparative studies between these imaging modalities are still limited. However we look forward to a time when this gap in literature will be fulfilled.

Determination of 3D Equilibria from Flux Surface Knowledge Only

DOE Office of Scientific and Technical Information (OSTI.GOV)

H.E. Mynick; N. Pomphrey

We show that the method of Christiansen and Taylor, from which complete tokamak equilibria can be determined given only knowledge of the shape of the flux surfaces, can be extended to 3-dimensional equilibria, such as those of stellarators. As for the tokamak case, the given geometric knowledge has a high degree of redundancy, so that the full equilibrium can be obtained using only a small portion of that information.

Leveraging Gibbs Ensemble Molecular Dynamics and Hybrid Monte Carlo/Molecular Dynamics for Efficient Study of Phase Equilibria.

PubMed

Gartner, Thomas E; Epps, Thomas H; Jayaraman, Arthi

2016-11-08

We describe an extension of the Gibbs ensemble molecular dynamics (GEMD) method for studying phase equilibria. Our modifications to GEMD allow for direct control over particle transfer between phases and improve the method's numerical stability. Additionally, we found that the modified GEMD approach had advantages in computational efficiency in comparison to a hybrid Monte Carlo (MC)/MD Gibbs ensemble scheme in the context of the single component Lennard-Jones fluid. We note that this increase in computational efficiency does not compromise the close agreement of phase equilibrium results between the two methods. However, numerical instabilities in the GEMD scheme hamper GEMD's use near the critical point. We propose that the computationally efficient GEMD simulations can be used to map out the majority of the phase window, with hybrid MC/MD used as a follow up for conditions under which GEMD may be unstable (e.g., near-critical behavior). In this manner, we can capitalize on the contrasting strengths of these two methods to enable the efficient study of phase equilibria for systems that present challenges for a purely stochastic GEMC method, such as dense or low temperature systems, and/or those with complex molecular topologies.

Stability of ideal MHD configurations. I. Realizing the generality of the G operator

NASA Astrophysics Data System (ADS)

Keppens, R.; Demaerel, T.

2016-12-01

A field theoretical approach, applied to the time-reversible system described by the ideal magnetohydrodynamic (MHD) equations, exposes the full generality of MHD spectral theory. MHD spectral theory, which classified waves and instabilities of static or stationary, usually axisymmetric or translationally symmetric configurations, actually governs the stability of flowing, (self-)gravitating, single fluid descriptions of nonlinear, time-dependent idealized plasmas, and this at any time during their nonlinear evolution. At the core of this theory is a self-adjoint operator G , discovered by Frieman and Rotenberg [Rev. Mod. Phys. 32, 898 (1960)] in its application to stationary (i.e., time-independent) plasma states. This Frieman-Rotenberg operator dictates the acceleration identified by a Lagrangian displacement field ξ , which connects two ideal MHD states in four-dimensional space-time that share initial conditions for density, entropy, and magnetic field. The governing equation reads /d 2 ξ d t 2 = G [ ξ ] , as first noted by Cotsaftis and Newcomb [Nucl. Fusion, Suppl. Part 2, 447 and 451 (1962)]. The time derivatives at left are to be taken in the Lagrangian way, i.e., moving with the flow v. Physically realizable displacements must have finite energy, corresponding to being square integrable in the Hilbert space of displacements equipped with an inner product rule, for which the G operator is self-adjoint. The acceleration in the left-hand side features the Doppler-Coriolis operator v . ∇ , which is known to become an antisymmetric operator when restricting attention to stationary equilibria. Here, we present all derivations needed to get to these insights and connect results throughout the literature. A first illustration elucidates what can happen when self-gravity is incorporated and presents aspects that have been overlooked even in simple uniform media. Ideal MHD flows, as well as Euler flows, have essentially 6 + 1 wave types, where the 6 wave modes

An Improved Lattice Boltzmann Model for Non-Newtonian Flows with Applications to Solid-Fluid Interactions in External Flows

NASA Astrophysics Data System (ADS)

Adam, Saad; Premnath, Kannan

2016-11-01

Fluid mechanics of non-Newtonian fluids, which arise in numerous settings, are characterized by non-linear constitutive models that pose certain unique challenges for computational methods. Here, we consider the lattice Boltzmann method (LBM), which offers some computational advantages due to its kinetic basis and its simpler stream-and-collide procedure enabling efficient simulations. However, further improvements are necessary to improve its numerical stability and accuracy for computations involving broader parameter ranges. Hence, in this study, we extend the cascaded LBM formulation by modifying its moment equilibria and relaxation parameters to handle a variety of non-Newtonian constitutive equations, including power-law and Bingham fluids, with improved stability. In addition, we include corrections to the moment equilibria to obtain an inertial frame invariant scheme without cubic-velocity defects. After preforming its validation study for various benchmark flows, we study the physics of non-Newtonian flow over pairs of circular and square cylinders in a tandem arrangement, especially the wake structure interactions and their effects on resulting forces in each cylinder, and elucidate the effect of the various characteristic parameters.

Variational principles for stochastic fluid dynamics

PubMed Central

Holm, Darryl D.

2015-01-01

This paper derives stochastic partial differential equations (SPDEs) for fluid dynamics from a stochastic variational principle (SVP). The paper proceeds by taking variations in the SVP to derive stochastic Stratonovich fluid equations; writing their Itô representation; and then investigating the properties of these stochastic fluid models in comparison with each other, and with the corresponding deterministic fluid models. The circulation properties of the stochastic Stratonovich fluid equations are found to closely mimic those of the deterministic ideal fluid models. As with deterministic ideal flows, motion along the stochastic Stratonovich paths also preserves the helicity of the vortex field lines in incompressible stochastic flows. However, these Stratonovich properties are not apparent in the equivalent Itô representation, because they are disguised by the quadratic covariation drift term arising in the Stratonovich to Itô transformation. This term is a geometric generalization of the quadratic covariation drift term already found for scalar densities in Stratonovich's famous 1966 paper. The paper also derives motion equations for two examples of stochastic geophysical fluid dynamics; namely, the Euler–Boussinesq and quasi-geostropic approximations. PMID:27547083

Calculation of continuum damping of Alfvén eigenmodes in tokamak and stellarator equilibria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowden, G. W.; Hole, M. J.; Könies, A.

2015-09-15

In an ideal magnetohydrodynamic (MHD) plasma, shear Alfvén eigenmodes may experience dissipationless damping due to resonant interaction with the shear Alfvén continuum. This continuum damping can make a significant contribution to the overall growth/decay rate of shear Alfvén eigenmodes, with consequent implications for fast ion transport. One method for calculating continuum damping is to solve the MHD eigenvalue problem over a suitable contour in the complex plane, thereby satisfying the causality condition. Such an approach can be implemented in three-dimensional ideal MHD codes which use the Galerkin method. Analytic functions can be fitted to numerical data for equilibrium quantities inmore » order to determine the value of these quantities along the complex contour. This approach requires less resolution than the established technique of calculating damping as resistivity vanishes and is thus more computationally efficient. The complex contour method has been applied to the three-dimensional finite element ideal MHD Code for Kinetic Alfvén waves. In this paper, we discuss the application of the complex contour technique to calculate the continuum damping of global modes in tokamak as well as torsatron, W7-X and H-1NF stellarator cases. To the authors' knowledge, these stellarator calculations represent the first calculation of continuum damping for eigenmodes in fully three-dimensional equilibria. The continuum damping of global modes in W7-X and H-1NF stellarator configurations investigated is found to depend sensitively on coupling to numerous poloidal and toroidal harmonics.« less

Seasonal multiphase equilibria in the atmospheres of Titan and Pluto

NASA Astrophysics Data System (ADS)

Tan, S. P.; Kargel, J. S.

2017-12-01

At the extremely low temperatures in Titan's upper troposphere and on Pluto's surface, the atmospheres as a whole are subject to freeze into solid solutions, not pure ices. The presence of the solid phases introduces conditions with rich phase equilibria upon seasonal changes, even if the temperature undergoes only small changes. For the first time, the profile of atmospheric methane in Titan's troposphere will be reproduced complete with the solid solutions. This means that the freezing point, i.e. the altitude where the first solid phase appears, is determined. The seasonal change will also be evaluated both at the equator and the northern polar region. For Pluto, also for the first time, the seasonal solid-vapor equilibria will be evaluated. The fate of the two solid phases, the methane-rich and carbon-monoxide-rich solid solutions, will be analyzed upon temperature and pressure changes. Such investigations are enabled by the development of a molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, which includes solid solutions in its phase-equilibria calculations. The atmospheres of Titan and Pluto are modeled as ternary gas mixtures: nitrogen-methane-ethane and nitrogen-methane-carbon monoxide, respectively. Calculations using CRYOCHEM can provide us with compositions not only in two-phase equilibria, but also that in three-phase equilibria. Densities of all phases involved will also be calculated. For Titan, density inversion between liquid and solid phases will be identified and presented. In the inversion, the density of solid phase is less than that in the liquid phase. The method and results of this work will be useful for further investigations and modeling on the atmospheres of Titan, Pluto, and other bodies with similar conditions in the Solar System and beyond.

High-beta analytic equilibria in circular, elliptical, and D-shaped large aspect ratio axisymmetric configurations with poloidal and toroidal flows

NASA Astrophysics Data System (ADS)

López, O. E.; Guazzotto, L.

2017-03-01

The Grad-Shafranov-Bernoulli system of equations is a single fluid magnetohydrodynamical description of axisymmetric equilibria with mass flows. Using a variational perturbative approach [E. Hameiri, Phys. Plasmas 20, 024504 (2013)], analytic approximations for high-beta equilibria in circular, elliptical, and D-shaped cross sections in the high aspect ratio approximation are found, which include finite toroidal and poloidal flows. Assuming a polynomial dependence of the free functions on the poloidal flux, the equilibrium problem is reduced to an inhomogeneous Helmholtz partial differential equation (PDE) subject to homogeneous Dirichlet conditions. An application of the Green's function method leads to a closed form for the circular solution and to a series solution in terms of Mathieu functions for the elliptical case, which is valid for arbitrary elongations. To extend the elliptical solution to a D-shaped domain, a boundary perturbation in terms of the triangularity is used. A comparison with the code FLOW [L. Guazzotto et al., Phys. Plasmas 11(2), 604-614 (2004)] is presented for relevant scenarios.

Gyrokinetic magnetohydrodynamics and the associated equilibria

NASA Astrophysics Data System (ADS)

Lee, W. W.; Hudson, S. R.; Ma, C. H.

2017-12-01

The gyrokinetic magnetohydrodynamic (MHD) equations, related to the recent paper by W. W. Lee ["Magnetohydrodynamics for collisionless plasmas from the gyrokinetic perspective," Phys. Plasmas 23, 070705 (2016)], and their associated equilibria properties are discussed. This set of equations consists of the time-dependent gyrokinetic vorticity equation, the gyrokinetic parallel Ohm's law, and the gyrokinetic Ampere's law as well as the equations of state, which are expressed in terms of the electrostatic potential, ϕ, and the vector potential, A , and support both spatially varying perpendicular and parallel pressure gradients and the associated currents. The corresponding gyrokinetic MHD equilibria can be reached when ϕ→0 and A becomes constant in time, which, in turn, gives ∇.(J∥+J⊥)=0 and the associated magnetic islands, if they exist. Examples of simple cylindrical geometry are given. These gyrokinetic MHD equations look quite different from the conventional MHD equations, and their comparisons will be an interesting topic in the future.

Gyrokinetic magnetohydrodynamics and the associated equilibria

DOE PAGES

Lee, W. W.; Hudson, S. R.; Ma, C. H.

2017-12-27

The gyrokinetic magnetohydrodynamic (MHD) equations, related to the recent paper by W. W. Lee, and their associated equilibria properties are discussed. This set of equations consists of the time-dependent gyrokinetic vorticity equation, the gyrokinetic parallel Ohm's law, and the gyrokinetic Ampere's law as well as the equations of state, which are expressed in terms of the electrostatic potential, Φ, and the vector potential, A, and support both spatially varying perpendicular and parallel pressure gradients and the associated currents. The corresponding gyrokinetic MHD equilibria can be reached when Φ → 0 and A becomes constant in time, which, in turn, givesmore » ∇· (J ∥+J ⊥) = 0 and the associated magnetic islands, if they exist. Examples of simple cylindrical geometry are given. In conclusion, these gyrokinetic MHD equations look quite different from the conventional MHD equations, and their comparisons will be an interesting topic in the future.« less

Gyrokinetic magnetohydrodynamics and the associated equilibria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, W. W.; Hudson, S. R.; Ma, C. H.

The gyrokinetic magnetohydrodynamic (MHD) equations, related to the recent paper by W. W. Lee, and their associated equilibria properties are discussed. This set of equations consists of the time-dependent gyrokinetic vorticity equation, the gyrokinetic parallel Ohm's law, and the gyrokinetic Ampere's law as well as the equations of state, which are expressed in terms of the electrostatic potential, Φ, and the vector potential, A, and support both spatially varying perpendicular and parallel pressure gradients and the associated currents. The corresponding gyrokinetic MHD equilibria can be reached when Φ → 0 and A becomes constant in time, which, in turn, givesmore » ∇· (J ∥+J ⊥) = 0 and the associated magnetic islands, if they exist. Examples of simple cylindrical geometry are given. In conclusion, these gyrokinetic MHD equations look quite different from the conventional MHD equations, and their comparisons will be an interesting topic in the future.« less

Solution influence on biomolecular equilibria - Nucleic acid base associations

NASA Technical Reports Server (NTRS)

Pohorille, A.; Pratt, L. R.; Burt, S. K.; Macelroy, R. D.

1984-01-01

Various attempts to construct an understanding of the influence of solution environment on biomolecular equilibria at the molecular level using computer simulation are discussed. First, the application of the formal statistical thermodynamic program for investigating biomolecular equilibria in solution is presented, addressing modeling and conceptual simplications such as perturbative methods, long-range interaction approximations, surface thermodynamics, and hydration shell. Then, Monte Carlo calculations on the associations of nucleic acid bases in both polar and nonpolar solvents such as water and carbon tetrachloride are carried out. The solvent contribution to the enthalpy of base association is positive (destabilizing) in both polar and nonpolar solvents while negative enthalpies for stacked complexes are obtained only when the solute-solute in vacuo energy is added to the total energy. The release upon association of solvent molecules from the first hydration layer around a solute to the bulk is accompanied by an increase in solute-solvent energy and decrease in solvent-solvent energy. The techniques presented are expectd to displace less molecular and more heuristic modeling of biomolecular equilibria in solution.

Thermodynamic characteristics of protolytic equilibria in aqueous solutions of glycyl peptides

NASA Astrophysics Data System (ADS)

Gridchin, S. N.

2016-11-01

Protolytic equilibria in aqueous solutions of glycyl-DL-serine, glycyl-DL-threonine, and glycyl-DL-valine are investigated by means of potentiometry and calorimetry. Dissociation constants and heat effects of the above dipeptides are determined. Standard thermodynamic characteristics (p K°, Δdis G°, Δdis H°, Δdis S°) of the investigated equilibria are calculated. The obtained results are compared to corresponding data on relative compounds.

Absorption fluids data survey

NASA Astrophysics Data System (ADS)

Macriss, R. A.; Zawacki, T. S.

Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

Conformal mapping for the Helmholtz equation: acoustic wave scattering by a two dimensional inclusion with irregular shape in an ideal fluid.

PubMed

Liu, Gang; Jayathilake, Pahala G; Khoo, Boo Cheong; Han, Feng; Liu, Dian Kui

2012-02-01

The complex variables method with mapping function was extended to solve the linear acoustic wave scattering by an inclusion with sharp/smooth corners in an infinite ideal fluid domain. The improved solutions of Helmholtz equation, shown as Bessel function with mapping function as the argument and fractional order Bessel function, were analytically obtained. Based on the mapping function, the initial geometry as well as the original physical vector can be transformed into the corresponding expressions inside the mapping plane. As all the physical vectors are calculated in the mapping plane (η,η), this method can lead to potential vast savings of computational resources and memory. In this work, the results are validated against several published works in the literature. The different geometries of the inclusion with sharp corners based on the proposed mapping functions for irregular polygons are studied and discussed. The findings show that the variation of angles and frequencies of the incident waves have significant influence on the bistatic scattering pattern and the far-field form factor for the pressure in the fluid. © 2012 Acoustical Society of America

Hydration and conformational equilibria of simple hydrophobic and amphiphilic solutes.

PubMed Central

Ashbaugh, H S; Kaler, E W; Paulaitis, M E

1998-01-01

We consider whether the continuum model of hydration optimized to reproduce vacuum-to-water transfer free energies simultaneously describes the hydration free energy contributions to conformational equilibria of the same solutes in water. To this end, transfer and conformational free energies of idealized hydrophobic and amphiphilic solutes in water are calculated from explicit water simulations and compared to continuum model predictions. As benchmark hydrophobic solutes, we examine the hydration of linear alkanes from methane through hexane. Amphiphilic solutes were created by adding a charge of +/-1e to a terminal methyl group of butane. We find that phenomenological continuum parameters fit to transfer free energies are significantly different from those fit to conformational free energies of our model solutes. This difference is attributed to continuum model parameters that depend on solute conformation in water, and leads to effective values for the free energy/surface area coefficient and Born radii that best describe conformational equilibrium. In light of these results, we believe that continuum models of hydration optimized to fit transfer free energies do not accurately capture the balance between hydrophobic and electrostatic contributions that determines the solute conformational state in aqueous solution. PMID:9675177

A stochastic cellular automata model of tautomer equilibria

NASA Astrophysics Data System (ADS)

Bowers, Gregory A.; Seybold, Paul G.

2018-03-01

Many chemical substances, including drugs and biomolecules, exist in solution not as a single species, but as a collection of tautomers and related species. Importantly, each of these species is an independent compoundwith its own specific biochemical and physicochemical properties. The species interconvert in a dynamic and often complicated manner, making modelling the overall species composition difficult. Agent-based cellular automata models are uniquely suited to meet this challenge, allowing the equilibria to be simulated using simple rulesand at the same time capturing the inherent stochasticity of the natural phenomenon. In the present example a stochastic cellular automata model is employed to simulate the tautomer equilibria of 9-anthrone and 9-anthrol in the presence of their common anion. The observed KE of the 9-anthrone ⇌ 9-anthrol tautomerisation along with the measured tautomer pKa values were used to model the equilibria at pH values 4, 7 and 10. At pH 4 and 7, the anthrone comprises >99% of the total species population, while at pH 10the anthrone and the anion each represent just under half of the total population. The advantages of the cellular automata approach over the customary coupled differential equation approach are discussed.

Reduced viscosity interpreted for fluid/gas mixtures

NASA Technical Reports Server (NTRS)

Lewis, D. H.

1981-01-01

Analysis predicts decrease in fluid viscosity by comparing pressure profile of fluid/gas mixture with that of power-law fluid. Fluid is taken to be viscous, non-Newtonian, and incompressible; the gas to be ideal; the flow to be inertia-free, isothermal, and one dimensional. Analysis assists in design of flow systems for petroleum, coal, polymers, and other materials.

The Statistical Mechanics of Ideal Homogeneous Turbulence

NASA Technical Reports Server (NTRS)

Shebalin, John V.

2002-01-01

Plasmas, such as those found in the space environment or in plasma confinement devices, are often modeled as electrically conducting fluids. When fluids and plasmas are energetically stirred, regions of highly nonlinear, chaotic behavior known as turbulence arise. Understanding the fundamental nature of turbulence is a long-standing theoretical challenge. The present work describes a statistical theory concerning a certain class of nonlinear, finite dimensional, dynamical models of turbulence. These models arise when the partial differential equations describing incompressible, ideal (i.e., nondissipative) homogeneous fluid and magnetofluid (i.e., plasma) turbulence are Fourier transformed into a very large set of ordinary differential equations. These equations define a divergenceless flow in a high-dimensional phase space, which allows for the existence of a Liouville theorem, guaranteeing a distribution function based on constants of the motion (integral invariants). The novelty of these particular dynamical systems is that there are integral invariants other than the energy, and that some of these invariants behave like pseudoscalars under two of the discrete symmetry transformations of physics, parity, and charge conjugation. In this work the 'rugged invariants' of ideal homogeneous turbulence are shown to be the only significant scalar and pseudoscalar invariants. The discovery that pseudoscalar invariants cause symmetries of the original equations to be dynamically broken and induce a nonergodic structure on the associated phase space is the primary result presented here. Applicability of this result to dissipative turbulence is also discussed.

Hydrostatic Equilibria of Rotating Stars with Realistic Equation of State

NASA Astrophysics Data System (ADS)

Yasutake, Nobutoshi; Fujisawa, Kotaro; Okawa, Hirotada; Yamada, Shoichi

Stars rotate generally, but it is a non-trivial issue to obtain hydrostatic equilibria for rapidly rotating stars theoretically, especially for baroclinic cases, in which the pressure depends not only on the density, but also on the temperature and compositions. It is clear that the stellar structures with realistic equation of state are the baroclinic cases, but there are not so many studies for such equilibria. In this study, we propose two methods to obtain hydrostatic equilibria considering rotation and baroclinicity, namely the weak-solution method and the strong-solution method. The former method is based on the variational principle, which is also applied to the calculation of the inhomogeneous phases, known as the pasta structures, in crust of neutron stars. We found this method might break the balance equation locally, then introduce the strong-solution method. Note that our method is formulated in the mass coordinate, and it is hence appropriated for the stellar evolution calculations.

Broken Ergodicity in Ideal, Homogeneous, Incompressible Turbulence

NASA Technical Reports Server (NTRS)

Morin, Lee; Shebalin, John; Fu, Terry; Nguyen, Phu; Shum, Victor

2010-01-01

We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.

Noise Production of an Idealized Two-Dimensional Fish School

NASA Astrophysics Data System (ADS)

Wagenhoffer, Nathan; Moored, Keith; Jaworski, Justin

2017-11-01

The analysis of quiet bio-inspired propulsive concepts requires a rapid, unified computational framework that integrates the coupled fluid-solid dynamics of swimmers and their wakes with the resulting noise generation. Such a framework is presented for two-dimensional flows, where the fluid motion is modeled by an unsteady boundary element method with a vortex-particle wake. The unsteady surface forces from the potential flow solver are then passed to an acoustic boundary element solver to predict the radiated sound in low-Mach-number flows. The coupled flow-acoustic solver is validated against canonical vortex-sound problems. A diamond arrangement of four airfoils are subjected to traveling wave kinematics representing a known idealized pattern for a school of fish, and the airfoil motion and inflow values are derived from the range of Strouhal values common to many natural swimmers. The coupled flow-acoustic solver estimates and analyzes the hydrodynamic performance and noise production of the idealized school of swimmers.

Computational fluid dynamics study of viscous fingering in supercritical fluid chromatography.

PubMed

Subraveti, Sai Gokul; Nikrityuk, Petr; Rajendran, Arvind

2018-01-26

Axi-symmetric numerical simulations are carried out to study the dynamics of a plug introduced through a mixed-stream injection in supercritical fluid chromatographic columns. The computational fluid dynamics model developed in this work takes into account both the hydrodynamics and adsorption equilibria to describe the phenomena of viscous fingering and plug effect that contribute to peak distortions in mixed-stream injections. The model was implemented into commercial computational fluid dynamics software using user-defined functions. The simulations describe the propagation of both the solute and modifier highlighting the interplay between the hydrodynamics and plug effect. The simulated peaks showed good agreement with experimental data published in the literature involving different injection volumes (5 μL, 50 μL, 1 mL and 2 mL) of flurbiprofen on Chiralpak AD-H column using a mobile phase of CO 2 and methanol. The study demonstrates that while viscous fingering is the main source of peak distortions for large-volume injections (1 mL and 2 mL) it has negligible impact on small-volume injections (5 μL and 50 μL). Band broadening in small-volume injections arise mainly due to the plug effect. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Diffusion-driven fluid dynamics in ideal gases and plasmas

NASA Astrophysics Data System (ADS)

Vold, E. L.; Yin, L.; Taitano, W.; Molvig, K.; Albright, B. J.

2018-06-01

The classical transport theory based on Chapman-Enskog methods provides self-consistent approximations for the kinetic flux of mass, heat, and momentum in a fluid limit characterized with a small Knudsen number. The species mass fluxes relative to the center of mass, or "diffusive fluxes," are expressed as functions of known gradient quantities with kinetic coefficients evaluated using similar analyses for mixtures of gases or plasma components. The sum over species of the diffusive mass fluxes is constrained to be zero in the Lagrange frame, and thus results in a non-zero molar flux leading to a pressure perturbation. At an interface between two species initially in pressure equilibrium, the pressure perturbation driven by the diffusive molar flux induces a center of mass velocity directed from the species of greater atomic mass towards the lighter atomic mass species. As the ratio of the species particle masses increases, this center of mass velocity carries an increasingly greater portion of the mass across the interface and for a particle mass ratio greater than about two, the center of mass velocity carries more mass than the gradient driven diffusion flux. Early time transients across an interface between two species in a 1D plasma regime and initially in equilibrium are compared using three methods; a fluid code with closure in a classical transport approximation, a particle in cell simulation, and an implicit Fokker-Planck solver for the particle distribution functions. The early time transient phenomenology is shown to be similar in each of the computational simulation methods, including a pressure perturbation associated with the stationary "induced" component of the center of mass velocity which decays to pressure equilibrium during diffusion. At early times, the diffusive process generates pressure and velocity waves which propagate outward from the interface and are required to maintain momentum conservation. The energy in the outgoing waves dissipates

Plasmoids everywhere: ideal tearing, the transition to fast reconnection, and solar activity.

NASA Astrophysics Data System (ADS)

Velli, M. C. M.; Pucci, F.; Tenerani, A.; Shi, C.; Del Sarto, D.; Rappazzo, A. F.

2017-12-01

We discuss the role of generalized ``ideal" tearing (IT) as a possible trigger mechanism for magnetic reconnection to understand energetic phenomena in the solar atmosphere. We begin with a pedagogical introduction to the IT concept, how it stems from the classical analysis of the tearing instability, what is meant by plasmoids, and the connections of IT to the plasmoid instability and Sweet Parker current sheets. We then proceed to analyze how the IT concept extends to equilibria with flows, small scale kinetic effects, different current structures and different magnetic field topology configurations. Finally we discuss the relationship of reconnection triggering to nonlinear cascades and turbulent evolution, and how different situations may arise depending on scale, boundary conditions, and time-history, from coronal heating via nanoflares, to solar flares and coronal mass ejections. Issues of local topology, dimensionality, anisotropy will also be discussed.

Equilibrator: Modeling Chemical Equilibria with Excel

ERIC Educational Resources Information Center

Vander Griend, Douglas A.

2011-01-01

Equilibrator is a Microsoft Excel program for learning about chemical equilibria through modeling, similar in function to EQS4WIN, which is no longer supported and does not work well with newer Windows operating systems. Similar to EQS4WIN, Equilibrator allows the user to define a system with temperature, initial moles, and then either total…

Acid-Base and Precipitation Equilibria in Wine

ERIC Educational Resources Information Center

Palma, Miguel; Barroso, Carmelo G.

2004-01-01

Experiments are performed to establish the changes of pH during the precipitation of potassium hydrogen tartrate, with its unfavorable impact on the stability of wine. Students, thus, obtain a clearer understanding of the interplay between a variety of chemical equilibria within a single medium.

The Gibbs free energy of nukundamite (Cu3.38Fe0.62S4): A correction and implications for phase equilibria

USGS Publications Warehouse

Seal, R.R.; Inan, E.E.; Hemingway, B.S.

2001-01-01

The Gibbs free energy of formation of nukundamite (Cu3.38Fe0.62S4) was calculated from published experimental studies of the reaction 3.25 Cu3.38Fe0.62S4 + S2 = 11 CuS + 2 FeS2 in order to correct an erroneous expression in the published record. The correct expression describing the Gibbs free energy of formation (kJ???mol-1) of nukundamite relative to the elements and ideal S2 gas is ??fG?? nukundamite T(K) = -549.75 + 0.23242 T + 3.1284 T0.5, with an uncertainty of 0.6%. An evaluation of the phase equilibria of nukundamite with associated phases in the system Cu-Fe-S as a function of temperature and sulfur fugacity indicates that nukundamite is stable from 224 to 501??C at high sulfidation states. At its greatest extent, at 434??C, the stability field of nukundamite is only 0.4 log f(S2) units wide, which explains its rarity. Equilibria between nukundamite and bornite, which limit the stability of both phases, involve bornite compositions that deviate significantly from stoichiometric Cu5FeS4. Under equilibrium conditions in the system Cu-Fe-S, nukundamite + chalcopyrite is not a stable assemblage at any temperature.

Finding Bounded Rational Equilibria. Part 1; Iterative Focusing

NASA Technical Reports Server (NTRS)

Wolpert, David H.

2004-01-01

A long-running difficulty with conventional game theory has been how to modify it to accommodate the bounded rationality characterizing all real-world players. A recurring issue in statistical physics is how best to approximate joint probability distributions with decoupled (and therefore far more tractable) distributions. It has recently been shown that the same information theoretic mathematical structure, known as Probability Collectives (PC) underlies both issues. This relationship between statistical physics and game theory allows techniques and insights from the one field to be applied to the other. In particular, PC provides a formal model-independent definition of the degree of rationality of a player and of bounded rationality equilibria. This pair of papers extends previous work on PC by introducing new computational approaches to effectively find bounded rationality equilibria of common-interest (team) games.

Nonlinear ideal magnetohydrodynamics instabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfirsch, D.; Sudan, R.N.

1993-07-01

Explosive phenomena such as internal disruptions in toroidal discharges and solar flares are difficult to explain in terms of linear instabilities. A plasma approaching a linear stability limit can, however, become nonlinearly and explosively unstable, with noninfinitesimal perturbations even before the marginal state is reached. For such investigations, a nonlinear extension of the usual MHD (magnetohydrodynamic) energy principle is helpful. (This was obtained by Merkel and Schlueter, Sitzungsberichted. Bayer. Akad. Wiss., Munich, 1976, No. 7, for Cartesian coordinate systems.) A coordinate system independent Eulerian formulation for the Lagrangian allowing for equilibria with flow and with built-in conservation laws for mass,more » magnetic flux, and entropy is developed in this paper which is similar to Newcomb's Lagrangian method of 1962 [Nucl. Fusion, Suppl., Pt. II, 452 (1962)]. For static equilibria nonlinear stability is completely determined by the potential energy. For a potential energy which contains second- and [ital n]th order or some more general contributions only, it is shown in full generality that linearly unstable and marginally stable systems are explosively unstable even for infinitesimal perturbations; linearly absolutely stable systems require finite initial perturbations. For equilibria with Abelian symmetries symmetry breaking initial perturbations are needed, which should be observed in numerical simulations. Nonlinear stability is proved for two simple examples, [ital m]=0 perturbations of a Bennet Z-pinch and [ital z]-independent perturbations of a [theta] pinch. The algebra for treating these cases reduces considerably if symmetries are taken into account from the outset, as suggested by M. N. Rosenbluth (private communication, 1992).« less

Nonlinear ideal magnetohydrodynamics instabilities

NASA Astrophysics Data System (ADS)

Pfirsch, D.; Sudan, R. N.

1993-07-01

Explosive phenomena such as internal disruptions in toroidal discharges and solar flares are difficult to explain in terms of linear instabilities. A plasma approaching a linear stability limit can, however, become nonlinearly and explosively unstable, with noninfinitesimal perturbations even before the marginal state is reached. For such investigations, a nonlinear extension of the usual MHD (magnetohydrodynamic) energy principle is helpful. (This was obtained by Merkel and Schlüter, Sitzungsberichted. Bayer. Akad. Wiss., Munich, 1976, No. 7, for Cartesian coordinate systems.) A coordinate system independent Eulerian formulation for the Lagrangian allowing for equilibria with flow and with built-in conservation laws for mass, magnetic flux, and entropy is developed in this paper which is similar to Newcomb's Lagrangian method of 1962 [Nucl. Fusion, Suppl., Pt. II, 452 (1962)]. For static equilibria nonlinear stability is completely determined by the potential energy. For a potential energy which contains second- and nth order or some more general contributions only, it is shown in full generality that linearly unstable and marginally stable systems are explosively unstable even for infinitesimal perturbations; linearly absolutely stable systems require finite initial perturbations. For equilibria with Abelian symmetries symmetry breaking initial perturbations are needed, which should be observed in numerical simulations. Nonlinear stability is proved for two simple examples, m=0 perturbations of a Bennet Z-pinch and z-independent perturbations of a θ pinch. The algebra for treating these cases reduces considerably if symmetries are taken into account from the outset, as suggested by M. N. Rosenbluth (private communication, 1992).

The J-S model versus a non-ideal MHD theory

NASA Astrophysics Data System (ADS)

Franchi, Franca; Lazzari, Barbara; Nibbi, Roberta

2015-07-01

A new non-ideal electromagnetic interpretation of the J-S type viscoelastic model for polymeric fluids is given and a generalized resisto-elastic magnetohydrodynamic scenario for collisionless plasmas is proposed. The influence of the new theory on the incompressible transverse Alfvén waves is thoroughly investigated.

Volumetric Properties and Fluid Phase Equilibria of CO2 + H2O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capobianco, Ryan; Gruszkiewicz, Miroslaw; Wesolowski, David J

2013-01-01

The need for accurate modeling of fluid-mineral processes over wide ranges of temperature, pressure and composition highlighted considerable uncertainties of available property data and equations of state, even for the CO2 + H2O binary system. In particular, the solubility, activity, and ionic dissociation equilibrium data for the CO2-rich phase, which are essential for understanding dissolution/precipitation, fluid-matrix reactions, and solute transport, are uncertain or missing. In this paper we report the results of a new experimental study of volumetric and phase equilibrium properties of CO2 + H2O, to be followed by measurements for bulk and confined multicomponent fluid mixtures. Mixture densitiesmore » were measured by vibrating tube densimetry (VTD) over the entire composition range at T = 200 and 250 C and P = 20, 40, 60, and 80 MPa. Initial analysis of the mutual solubilities, determined from volumetric data, shows good agreement with earlier results for the aqueous phase, but finds that the data of Takenouchi and Kennedy (1964) significantly overestimated the solubility of water in supercritical CO2 (by a factor of more than two at 200 C). Resolving this well-known discrepancy will have a direct impact on the accuracy of predictive modeling of CO2 injection in geothermal reservoirs and geological carbon sequestration through improved equations of state, needed for calibration of predictive molecular-scale models and large-scale reactive transport simulations.« less

A decentralized process for finding equilibria given by linear equations.

PubMed Central

Reiter, S

1994-01-01

I present a decentralized process for finding the equilibria of an economy characterized by a finite number of linear equilibrium conditions. The process finds all equilibria or, if there are none, reports that, in a finite number of steps at most equal to the number of equations. The communication and computational complexity compare favorably with other decentralized processes. The process may also be interpreted as an algorithm for solving a distributed system of linear equations. Comparisons with the Linpack program for LU (lower and upper triangular decomposition of the matrix of the equation system, a version of Gaussian elimination) are presented. PMID:11607486

Ideal GLM-MHD: About the entropy consistent nine-wave magnetic field divergence diminishing ideal magnetohydrodynamics equations

NASA Astrophysics Data System (ADS)

Derigs, Dominik; Winters, Andrew R.; Gassner, Gregor J.; Walch, Stefanie; Bohm, Marvin

2018-07-01

The paper presents two contributions in the context of the numerical simulation of magnetized fluid dynamics. First, we show how to extend the ideal magnetohydrodynamics (MHD) equations with an inbuilt magnetic field divergence cleaning mechanism in such a way that the resulting model is consistent with the second law of thermodynamics. As a byproduct of these derivations, we show that not all of the commonly used divergence cleaning extensions of the ideal MHD equations are thermodynamically consistent. Secondly, we present a numerical scheme obtained by constructing a specific finite volume discretization that is consistent with the discrete thermodynamic entropy. It includes a mechanism to control the discrete divergence error of the magnetic field by construction and is Galilean invariant. We implement the new high-order MHD solver in the adaptive mesh refinement code FLASH where we compare the divergence cleaning efficiency to the constrained transport solver available in FLASH (unsplit staggered mesh scheme).

Phase Equilibria Modeling of Coesite Eclogite from the Sulu Belt, Eastern China

NASA Astrophysics Data System (ADS)

Xia, B.; Brown, M.; Wang, L.; Wang, S.; Piccoli, P. M.

2016-12-01

Modeling of phase equilibria and tectonic processes are essential components to understand controls on P-T paths of UHPM rocks. However, diffusion at higher temperatures (> 700 °C), and issues with determination of Fe3+ in minerals and estimating H2O contents limit our ability to determine prograde, peak P and retrograde P-T data. Also, the lack of an appropriate activity-composition model for melt in basic rocks has limited the application of phase equilibria modeling to understand partial melting associated with exhumation. Here we apply phase equilibria modeling to coesite eclogite from Yangkou to assess the influence of Fe3+ and fluid during metamorphism, monitor reactions and phase relations in eclogite during deep subduction and exhumation and investigate partial melting at HP conditions. The modeling used the THERMOCALC software and the new internally consistent thermodynamic dataset for basic rocks (http://www.metamorph.geo.uni-mainz.de/thermocalc/dataset6/index.html). Here we investigate bimineralic (gt+omp+coe/qz+ru/ilm), phengite-bearing (gt+omp+phen (2 samples, <5 vol% and >5 vol%) +coe/qz+ru/ilm) and kyanite-bearing (gt+omp+phen+ky+coe/qz+ru/ilm) eclogites. Coesite in the matrix is the hallmark of the Yangkou eclogite. For each sample, we use an iterative process to estimate the H2O and O content in the bulk composition, and then calculate a P-T pseudosection. The results suggest that some prograde information (670-770 °C, > 3.0 GPa) is retained in large garnet cores in bimineralic and phengite-bearing eclogite. The peak P-T conditions are a challenge because in the field of gt+omp+coe/qz±phen+H2O at T > 750 °C and P > 3.5 GPa mode and compositional changes are small. However, isopleths of Si in phengite suggest that the peak P could have been > 5-6 GPa. Re-equilibration of garnet and omphacite compositions occurred during exhumation, yielding P-T conditions of 700-790 °C at 3.1-2.0 GPa. Amphibolite facies metamorphism occurred at 630-710 °C, 1

Plasma Equilibria With Stochastic Magnetic Fields

NASA Astrophysics Data System (ADS)

Krommes, J. A.; Reiman, A. H.

2009-05-01

Plasma equilibria that include regions of stochastic magnetic fields are of interest in a variety of applications, including tokamaks with ergodic limiters and high-pressure stellarators. Such equilibria are examined theoretically, and a numerical algorithm for their construction is described.^2,3 % The balance between stochastic diffusion of magnetic lines and small effects^2 omitted from the simplest MHD description can support pressure and current profiles that need not be flattened in stochastic regions. The diffusion can be described analytically by renormalizing stochastic Langevin equations for pressure and parallel current j, with particular attention being paid to the satisfaction of the periodicity constraints in toroidal configurations with sheared magnetic fields. The equilibrium field configuration can then be constructed by coupling the prediction for j to Amp'ere's law, which is solved numerically. A. Reiman et al., Pressure-induced breaking of equilibrium flux surfaces in the W7AS stellarator, Nucl. Fusion 47, 572--8 (2007). J. A. Krommes and A. H. Reiman, Plasma equilibrium in a magnetic field with stochastic regions, submitted to Phys. Plasmas. J. A. Krommes, Fundamental statistical theories of plasma turbulence in magnetic fields, Phys. Reports 360, 1--351.

Phase Equilibria of the Brine Systems Containing Strontium and Calcium Ions

NASA Astrophysics Data System (ADS)

Wang, Xia; Zhao, Kaiyu; Li, Long; Guo, Yafei; Meng, Lingzong; Deng, Tianlong

2017-12-01

It is well known that the comprehensive utilization of the Salt Lake resources successfully must be guided corresponding to the aqueous phase equilibria and phase diagrams. Researches on the phase relationships of brine systems containing calcium and strontium ions are essential to promote the development for the relative resources discovered in China at recent years. In this paper, the phase equilibria of calcium-containing systems, strontium-containing systems and calcium-strontium coexisted brine systems around the world were reviewed. The problems existed recently and new trends in future were point out.

Signaling equilibria in sensorimotor interactions.

PubMed

Leibfried, Felix; Grau-Moya, Jordi; Braun, Daniel A

2015-08-01

Although complex forms of communication like human language are often assumed to have evolved out of more simple forms of sensorimotor signaling, less attention has been devoted to investigate the latter. Here, we study communicative sensorimotor behavior of humans in a two-person joint motor task where each player controls one dimension of a planar motion. We designed this joint task as a game where one player (the sender) possesses private information about a hidden target the other player (the receiver) wants to know about, and where the sender's actions are costly signals that influence the receiver's control strategy. We developed a game-theoretic model within the framework of signaling games to investigate whether subjects' behavior could be adequately described by the corresponding equilibrium solutions. The model predicts both separating and pooling equilibria, in which signaling does and does not occur respectively. We observed both kinds of equilibria in subjects and found that, in line with model predictions, the propensity of signaling decreased with increasing signaling costs and decreasing uncertainty on the part of the receiver. Our study demonstrates that signaling games, which have previously been applied to economic decision-making and animal communication, provide a framework for human signaling behavior arising during sensorimotor interactions in continuous and dynamic environments. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamics and stability of a 2D ideal vortex under external strain

NASA Astrophysics Data System (ADS)

Hurst, N. C.; Danielson, J. R.; Dubin, D. H. E.; Surko, C. M.

2017-11-01

The behavior of an initially axisymmetric 2D ideal vortex under an externally imposed strain flow is studied experimentally. The experiments are carried out using electron plasmas confined in a Penning-Malmberg trap; here, the dynamics of the plasma density transverse to the field are directly analogous to the dynamics of vorticity in a 2D ideal fluid. An external strain flow is applied using boundary conditions in a way that is consistent with 2D fluid dynamics. Data are compared to predictions from a theory assuming a piecewise constant elliptical vorticity distribution. Excellent agreement is found for quasi-flat profiles, whereas the dynamics of smooth profiles feature modified stability limits and inviscid damping of periodic elliptical distortions. This work supported by U.S. DOE Grants DE-SC0002451 and DE-SC0016532, and NSF Grant PHY-1414570.

Initial eccentricity and constituent quark number scaling of elliptic flow in ideal and viscous dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaudhuri, A. K.

2010-04-15

In the Israel-Stewart theory of dissipative hydrodynamics, the scaling properties of elliptic flow in Au+Au collisions are studied. The initial energy density of the fluid was fixed to reproduce STAR data on phi-meson multiplicity in 0-5% Au+Au collisions such that, irrespective of fluid viscosity, entropy at the freeze-out is similar in ideal or in viscous evolution. The initial eccentricity or constituent quark number scaling is only approximate in ideal or minimally viscous (eta/s=1/4pi) fluid. Eccentricity scaling becomes nearly exact in more viscous fluid (eta/s>=0.12). However, in more viscous fluid, constituent quark number scaled elliptic flow for mesons and baryons splitsmore » into separate scaling functions. Simulated flows also do not exhibit 'universal scaling'; that is, elliptic flow scaled by the constituent quark number and charged particles v{sub 2} is not a single function of transverse kinetic energy scaled by the quark number. From a study of the violation of universal scaling, we obtain an estimate of quark-gluon plasma viscosity, eta/s=0.12+-0.03. The error is statistical only. The systematic error in eta/s could be as large.« less

Predicting vapor-liquid phase equilibria with augmented ab initio interatomic potentials

NASA Astrophysics Data System (ADS)

Vlasiuk, Maryna; Sadus, Richard J.

2017-06-01

The ability of ab initio interatomic potentials to accurately predict vapor-liquid phase equilibria is investigated. Monte Carlo simulations are reported for the vapor-liquid equilibria of argon and krypton using recently developed accurate ab initio interatomic potentials. Seventeen interatomic potentials are studied, formulated from different combinations of two-body plus three-body terms. The simulation results are compared to either experimental or reference data for conditions ranging from the triple point to the critical point. It is demonstrated that the use of ab initio potentials enables systematic improvements to the accuracy of predictions via the addition of theoretically based terms. The contribution of three-body interactions is accounted for using the Axilrod-Teller-Muto plus other multipole contributions and the effective Marcelli-Wang-Sadus potentials. The results indicate that the predictive ability of recent interatomic potentials, obtained from quantum chemical calculations, is comparable to that of accurate empirical models. It is demonstrated that the Marcelli-Wang-Sadus potential can be used in combination with accurate two-body ab initio models for the computationally inexpensive and accurate estimation of vapor-liquid phase equilibria.

Density-functional study on the equilibria in the ThDP activation.

PubMed

Delgado, Eduardo J; Alderete, Joel B; Jaña, Gonzalo A

2011-11-01

The equilibria among the various ionization and tautomeric states involved in the activation of ThDP is addressed using high level density functional theory calculations, X3LYP/6-311++G(d,p)//X3LYP(PB)/6-31++G(d,p). This study provides the first theoretically derived thermodynamic data for the internal equilibria in the activation of ThDP. The role of the medium polarity on the geometry and thermodynamics of the diverse equilibria of ThDP is addressed. The media chosen are cyclohexane and water, as paradigms of apolar and polar media. The results suggest that all ionization and tautomeric states are accessible during the catalytic cycle, even in the absence of substrate, being APH(+) the form required to interconvert the AP and IP tautomers; and the generation of the ylide proceeds via the formation of the IP form. Additionally, the calculated ΔG° values allow to calculate all the equilibrium constants, including the pK(C2) for the thiazolium C2 atom whose ionization is believed to initiate the catalytic cycle.

Predicting vapor-liquid phase equilibria with augmented ab initio interatomic potentials.

PubMed

Vlasiuk, Maryna; Sadus, Richard J

2017-06-28

The ability of ab initio interatomic potentials to accurately predict vapor-liquid phase equilibria is investigated. Monte Carlo simulations are reported for the vapor-liquid equilibria of argon and krypton using recently developed accurate ab initio interatomic potentials. Seventeen interatomic potentials are studied, formulated from different combinations of two-body plus three-body terms. The simulation results are compared to either experimental or reference data for conditions ranging from the triple point to the critical point. It is demonstrated that the use of ab initio potentials enables systematic improvements to the accuracy of predictions via the addition of theoretically based terms. The contribution of three-body interactions is accounted for using the Axilrod-Teller-Muto plus other multipole contributions and the effective Marcelli-Wang-Sadus potentials. The results indicate that the predictive ability of recent interatomic potentials, obtained from quantum chemical calculations, is comparable to that of accurate empirical models. It is demonstrated that the Marcelli-Wang-Sadus potential can be used in combination with accurate two-body ab initio models for the computationally inexpensive and accurate estimation of vapor-liquid phase equilibria.

Effect of initial densities in the lattice Boltzmann model for non-ideal fluid with curved interface

NASA Astrophysics Data System (ADS)

Gong, Jiaming; Oshima, Nobuyuki

2017-06-01

The effect of initial densities in a free energy based two-phase-flow lattice Boltzmann method for non-ideal fluids with a curved interface was investigated in the present work. To investigate this effect, the initial densities in the liquid and gas phases coming from the saturation points and the equilibrium state were adopted in the simulation of a static droplet in an open and a closed system. For the purpose of simplicity and easier comparison, the closed system is fabricated by the implementation of the periodic boundary condition at the inlet and outlet of a gas channel, and the open system is fabricated by the implementation of a constant flux boundary condition at the inlet and a free-out boundary condition at the outlet of the same gas channel. By comparing the simulation results from the two types of initial densities in the open and closed systems, it is proven that the commonly used saturation initial densities setting is the reason for droplet mass and volume variation which occurred in the simulation, particularly in the open system with a constant flux boundary condition. Such problems are believed to come from the curvature effect of the surface tension and can be greatly reduced by adopting the initial densities in the two phases from equilibrium state.

Performance of journal bearings with semi-compressible fluids

NASA Technical Reports Server (NTRS)

Carpino, M.; Peng, J.-P.

1991-01-01

Cryogenic fluids in isothermal rigid surface and foil type journal bearings can sometimes be treated as semicompressible fluids. In these applications, the fluid density is a function of the pressure. At low pressures, the fluids can change from a liquid to a saturated liquid-vapor phase. The performance of a rigid surface journal bearing with an idealized semicompressible fluid is discussed. Pressure solutions are based upon a Reynolds equation which includes the effects of a compressibility via the bulk modulus of the fluid. Results are contrasted with the performance of isothermal constant property incompressible fluids.

Exact Solutions to Several Nonlinear Cases of Generalized Grad-Shafranov Equation for Ideal Magnetohydrodynamic Flows in Axisymmetric Domain

NASA Astrophysics Data System (ADS)

Adem, Abdullahi Rashid; Moawad, Salah M.

2018-05-01

In this paper, the steady-state equations of ideal magnetohydrodynamic incompressible flows in axisymmetric domains are investigated. These flows are governed by a second-order elliptic partial differential equation as a type of generalized Grad-Shafranov equation. The problem of finding exact equilibria to the full governing equations in the presence of incompressible mass flows is considered. Two different types of constraints on position variables are presented to construct exact solution classes for several nonlinear cases of the governing equations. Some of the obtained results are checked for their applications to magnetic confinement plasma. Besides, they cover many previous configurations and include new considerations about the nonlinearity of magnetic flux stream variables.

Modeling of multiple equilibria in the self-aggregation of di-n-decyldimethylammonium chloride/octaethylene glycol monododecyl ether/cyclodextrin ternary systems.

PubMed

Leclercq, Loïc; Lubart, Quentin; Aubry, Jean-Marie; Nardello-Rataj, Véronique

2013-05-28

The surface tension equations of binary surfactant mixtures (di-n-decyldimethylammonium chloride and octaethylene glycol monododecyl ether) are established by combining the Szyszkowski equation of surfactant solutions, the ideal or nonideal mixing theory, and the phase separation model. For surfactant mixtures, the surface tension at the air-water interface is calculated using nonideal theory due to synergism between the two adsorbed surfactant types. The incorporation of cyclodextrin complexation model to the surface tension equations gives a robust model for the description of the surface tension isotherms of binary, ternary, and more complex systems involving numerous inclusion complexes. The surface tension data obtained experimentally shows excellent agreement with the theoretical model below and above the formation of micelles. The strong synergistic effect observed between the two surfactants is disrupted by the presence of CDs, leading to ideal behavior of ternary systems. Indeed, depending on the nature of the cyclodextrin (i.e., α, β, or γ), which allows a tuning of the cavity size, the binding constants with the surfactants are modified as well as the surface properties due to strong modification of equilibria involved in the ternary mixture.

Microbial control of mineral–groundwater equilibria:Macroscale to microscale

USGS Publications Warehouse

Bennett, Philip C.; Hiebert, Franz K.; Roger, Jennifer Roberts

2000-01-01

macroscaleprocesses that perturb general groundwater chemistry and therefore mineral–water equilibria; and microscale interactions, where attached organisms locally perturb mineral–water equilibria, potentially releasing limiting trace nutrients from the dissolving mineral.In the contaminated unconfined glacio-fluvial aquifer near Bemidji, Minnesota, USA, carbonate chemistry is influenced primarily at the macroscale. Under oxic conditions, respiration by native aerobic heterotrophs produces excess carbon dioxide that promotes calcite and dolomite dissolution. Aerobic microorganisms do not colonize dolomite surfaces and few occur on calcite. Within the anoxic groundwater, calcite overgrowths form on uncolonized calcite cleavage surfaces, possibly due to the consumption of acidity by dissimilatory iron-reducing bacteria. As molecular oxygen concentration increases downgradient of the oil pool, aerobes again dominate and residual hydrocarbons and ferrous iron are oxidized, resulting in macroscale carbonate-mineral dissolution and iron precipitation.

Predicting phase equilibria in one-component systems

NASA Astrophysics Data System (ADS)

Korchuganova, M. R.; Esina, Z. N.

2015-07-01

It is shown that Simon equation coefficients for n-alkanes and n-alcohols can be modeled using critical and triple point parameters. Predictions of the phase liquid-vapor, solid-vapor, and liquid-solid equilibria in one-component systems are based on the Clausius-Clapeyron relation, Van der Waals and Simon equations, and the principle of thermodynamic similarity.

In situ experimental study of subduction zone fluids using diamond anvil cells

NASA Astrophysics Data System (ADS)

Bureau, H.; Foy, E.; Somogyi, A.; Munsch, P.; Simon, G.; Kubsky, S.

2008-12-01

Experiments carried out in diamond anvil cells combined with in situ synchrotron light source measurements represent the only one issue to observe and study fluid equilibria in real time, at the pressure and temperature conditions of the subduction zones. We will present new results recently obtained at the DIFFABS beam line (SOLEIL Synchrotron) aiming at studying equilibria between silica-rich hydrous melts and aqueous fluids in the presence of U, Th, Pb, Ba and Br. We used synchrotron X-Ray fluorescence analysis performed in situ in Bassett-modified hydrothermal diamond anvil cells in order to monitor the chemical transfers of the studied elements between the phases in equilibrium at different pressures (up to 1.6 GPa) and temperatures (up to 900°C). We have calculated the partition coefficients for each studied element (i): Difluid/melt = Cifluid/Cimelt. Results show that U and Th exhibit more affinities for the silica-rich hydrous fluids in the presence or absence of Br, considered here such as an analogue for Cl, (i.e. 0.4 < DUfluid/melt < 0.7 depending on P,T conditions). Br partitioning shows that whereas this halogen element has very strong affinity to the aqueous fluid during magma degassing (DBrfluid/melt >> 10 after decompression) this coefficient decreases with pressure suggesting that Br would not be immediately washed out from the subducted plate during dehydration but may be recycled deeper in the mantle. These new data combined with previous ones obtained for Pb, Ba (Bureau et al., 2007, HPR vol 27, p. 235) and Rb, Sr, Zr (Bureau et al., 2004, Eos Trans. AGU, 85(47), V11C-05), allow us to propose a general outline of the fluid phase transfers through the subduction factory: (1) at shallow level: their nature and composition, the impact of the presence of halogens and the fertilizing role of such fluids in the mantle wedge, where the generation of arc magmas takes place (2) deeper in the mantle: where hydrous silica-rich supercritical fluids may

Stability of Inhomogeneous Equilibria of Hamiltonian Continuous Media Field Theories

NASA Astrophysics Data System (ADS)

Hagstrom, George

2013-10-01

There are a wide variety of 1 + 1 Hamiltonian continuous media field theories that exhibit phase space pattern formation. In plasma physics, the most famous of these is the Vlasov-Poisson equation, but other examples include the incompressible Euler equation in two-dimensions and the Hamiltonian Mean Field (or XY) model. One of the characteristic phenomenon that occurs in systems described by these equations is the formation of cat's eye patterns in phase space as a result of the nonlinear saturation of instabilities. Corresponding to each of these cat's eyes is a spatially inhomogeneous equilibrium solution of the underlying model, in plasma physics these are called BGK modes, but analogous solutions exist in all of the above systems. Here we analyze the stability of inhomogeneous equilibria in the Hamiltonian Mean Field model and in the Single Wave model, which is an equation that was derived to provide a model of the formation of electron holes in plasmas. We use action angle variables and the properties of elliptic functions to analyze the resulting dispersion relation construct linearly stable inhomogeneous equilibria for in the limit of small numbers of particles and study the behavior of solutions near these equilibria. Work supported by USDOE grant no. DE-FG02-ER53223.

Hydrogen exchange equilibria in thiols.

PubMed

Hofstetter, Dustin; Thalmann, Basil; Nauser, Thomas; Koppenol, Willem H

2012-09-17

Cysteine, cysteinyl-glycine, glutathione, phenylalanyl-cysteinyl-glycine, and histidyl-cysteinyl-glycine were dissolved in acidic and neutral D(2)O in the presence of the radical generator 2,2'-azobis(2-methylpropionamidine) dihydrochloride and radical mediator compounds (benzyl alcohol and 2-propanol). An exchange of H-atoms by D-atoms took place in these peptides due to intramolecular H-abstraction equilibria. NMR measurements allow one to follow the extent of H-D exchanges and to identify the sites where these exchanges take place. Significant exchanges occur in acidic media in GSH at positions Glu-β and Glu-γ, in Phe-Cys-Gly at positions Phe ortho, Phe-β, Cys-α, Cys-β, and Gly-α, and in His-Cys-Gly at positions His H1, His H2, His β, Cys β, and Gly α. In neutral media, exchanges occur in Cys-Gly at position Cys β and in GSH at position Cys α. Phe-Cys-Gly and His-Cys-Gly were not examined in neutral media. Sites participating in the radical exchange equilibria are highly dependent on structure and pH; the availability of electron density in the form of lone pairs appears to increase the extent of exchange. Interestingly, and unexpectedly, 2D NMR experiments show that GSH rearranges itself in acidic solution: the signals shift, but their patterns do not change. The formation of a thiolactone from Gly and Cys residues matches the changes observed.

Another dimension to metamorphic phase equilibria: the power of interactive movies for understanding complex phase diagram sections

NASA Astrophysics Data System (ADS)

Moulas, E.; Caddick, M. J.; Tisato, N.; Burg, J.-P.

2012-04-01

The investigation of metamorphic phase equilibria, using software packages that perform thermodynamic calculations, involves a series of important assumptions whose validity can often be questioned but are difficult to test. For example, potential influences of deformation on phase relations, and modification of effective reactant composition (X) at successive stages of equilibrium may both introduce significant uncertainty into phase diagram calculations. This is generally difficult to model with currently available techniques, and is typically not well quantified. We present here a method to investigate such phenomena along pre-defined Pressure-Temperature (P-T) paths, calculating local equilibrium via Gibbs energy minimization. An automated strategy to investigate complex changes in the effective equilibration composition has been developed. This demonstrates the consequences of specified X modification and, more importantly, permits automated calculation of X changes that are likely along the requested path if considering several specified processes. Here we describe calculations considering two such processes and show an additional example of a metamorphic texture that is difficult to model with current techniques. Firstly, we explore the assumption that although water saturation and bulk-rock equilibrium are generally considered to be valid assumptions in the calculation of phase equilibria, the saturation of thermodynamic components ignores mechanical effects that the fluid/melt phase can impose on the rock, which in turn can modify the effective equilibrium composition. Secondly, we examine how mass fractionation caused by porphyroblast growth at low temperatures or progressive melt extraction at high temperatures successively modifies X out of the plane of the initial diagram, complicating the process of determining best-fit P-T paths for natural samples. In particular, retrograde processes are poorly modeled without careful consideration of prograde

Relativistic Self-similar Equilibria and Non-axisymmetric Neutral Modes

NASA Astrophysics Data System (ADS)

Cai, Mike J.; Shu, F. H.

2002-05-01

We have constructed semi-analytic axisymmetric scale free solutions to Einstein field equations with perfect fluid matter source. These spacetimes are self-similar under the simultaneous transformation r'= ar and t'=a1-nt. We explored the two dimensional solution space parameterized by the rescaling index n and the isothermal sound speed γ 1/2. The isopycnic surfaces are in general toroids. As the equilibrium configuration rotates faster, an ergo region develops in the form of the exterior of a cone centered about the symmetry axis. The sequence of solution terminates when frame dragging becomes infinite and the ergo cone closes onto the axis. In the extreme flattening limit, we have also searched for non-axisymmetric neutral modes in a self-similar disk. Two separate sets of tracks are discovered in the solution space. One corresponds to the bifurcation points to non-axisymmetric equilibria, which is confined in the non-ergo solutions. The other track signals the onset of instability driven by gravitational radiation. These solutions are formally infinite in extent, and thus can not represent realistic astrophysical systems. However, if these properties do not alter qualitatively when the self-similar configurations are truncated, then these solutions may serve as initial data for dynamic collapse in super massive black hole formation.

Free boundary skin current magnetohydrodynamic equilibria

NASA Astrophysics Data System (ADS)

Reusch, Michael F.

1988-10-01

Function theoretic methods in the complex plane are used to develop simple parametric hodograph formulas that generate sharp boundary equilibria of arbitrary shape. The related method of Gorenflo [Z. Angew. Math. Phys. 16, 279 (1965)] and Merkel (Ph.D. thesis, University of Munich, 1965) is discussed. A numerical technique for the construction of solutions, based on one of the methods, is presented. A study is made of the bifurcations of an equilibrium of general form.

Multiple Equilibria and Endogenous Cycles in a Non-Linear Harrodian Growth Model

NASA Astrophysics Data System (ADS)

Commendatore, Pasquale; Michetti, Elisabetta; Pinto, Antonio

The standard result of Harrod's growth model is that, because investors react more strongly than savers to a change in income, the long run equilibrium of the economy is unstable. We re-interpret the Harrodian instability puzzle as a local instability problem and integrate his model with a nonlinear investment function. Multiple equilibria and different types of complex behaviour emerge. Moreover, even in the presence of locally unstable equilibria, for a large set of initial conditions the time path of the economy is not diverging, providing a solution to the instability puzzle.

Dynamics of Perturbed Relative Equilibria of Point Vortices on the Sphere or Plane

NASA Astrophysics Data System (ADS)

Patrick, G. W.

2000-06-01

, and there are stable relative equilibria of four point vortices, where three identical point vortices form an equilateral triangle circling a central vortex. These relative equilibria have zero (nongeneric) momentum and form a family that extends to arbitrarily small diameters. Using the energy-momentum method, I show their shape is stable while their location on the sphere is unstable, and they move, after perturbation to nonzero momentum, on the sphere as point particles move under the influence of a magnetic monopole. In the analysis the internal and external degrees of freedom are separated and the mass of these point particles determined. In addition, two identical such relative equilibria attract one another, while opposites repel, and in energetic collisions, opposites disintegrate to vortex pairs while identicals interact by exchanging a vortex. An analogous situation also occurs for the planar system with its noncompact SE(2) symmetry.

A group contribution method for associating chain molecules based on the statistical associating fluid theory (SAFT-γ)

NASA Astrophysics Data System (ADS)

Lymperiadis, Alexandros; Adjiman, Claire S.; Galindo, Amparo; Jackson, George

2007-12-01

A predictive group-contribution statistical associating fluid theory (SAFT-γ) is developed by extending the molecular-based SAFT-VR equation of state [A. Gil-Villegas et al. J. Chem. Phys. 106, 4168 (1997)] to treat heteronuclear molecules which are formed from fused segments of different types. Our models are thus a heteronuclear generalization of the standard models used within SAFT, comparable to the optimized potentials for the liquid state OPLS models commonly used in molecular simulation; an advantage of our SAFT-γ over simulation is that an algebraic description for the thermodynamic properties of the model molecules can be developed. In our SAFT-γ approach, each functional group in the molecule is modeled as a united-atom spherical (square-well) segment. The different groups are thus characterized by size (diameter), energy (well depth) and range parameters representing the dispersive interaction, and by shape factor parameters (which denote the extent to which each group contributes to the overall molecular properties). For associating groups a number of bonding sites are included on the segment: in this case the site types, the number of sites of each type, and the appropriate association energy and range parameters also have to be specified. A number of chemical families (n-alkanes, branched alkanes, n-alkylbenzenes, mono- and diunsaturated hydrocarbons, and n-alkan-1-ols) are treated in order to assess the quality of the SAFT-γ description of the vapor-liquid equilibria and to estimate the parameters of various functional groups. The group parameters for the functional groups present in these compounds (CH3, CH2, CH3CH, ACH, ACCH2, CH2, CH , and OH) together with the unlike energy parameters between groups of different types are obtained from an optimal description of the pure component phase equilibria. The approach is found to describe accurately the vapor-liquid equilibria with an overall %AAD of 3.60% for the vapor pressure and 0.86% for

A group contribution method for associating chain molecules based on the statistical associating fluid theory (SAFT-gamma).

PubMed

Lymperiadis, Alexandros; Adjiman, Claire S; Galindo, Amparo; Jackson, George

2007-12-21

A predictive group-contribution statistical associating fluid theory (SAFT-gamma) is developed by extending the molecular-based SAFT-VR equation of state [A. Gil-Villegas et al. J. Chem. Phys. 106, 4168 (1997)] to treat heteronuclear molecules which are formed from fused segments of different types. Our models are thus a heteronuclear generalization of the standard models used within SAFT, comparable to the optimized potentials for the liquid state OPLS models commonly used in molecular simulation; an advantage of our SAFT-gamma over simulation is that an algebraic description for the thermodynamic properties of the model molecules can be developed. In our SAFT-gamma approach, each functional group in the molecule is modeled as a united-atom spherical (square-well) segment. The different groups are thus characterized by size (diameter), energy (well depth) and range parameters representing the dispersive interaction, and by shape factor parameters (which denote the extent to which each group contributes to the overall molecular properties). For associating groups a number of bonding sites are included on the segment: in this case the site types, the number of sites of each type, and the appropriate association energy and range parameters also have to be specified. A number of chemical families (n-alkanes, branched alkanes, n-alkylbenzenes, mono- and diunsaturated hydrocarbons, and n-alkan-1-ols) are treated in order to assess the quality of the SAFT-gamma description of the vapor-liquid equilibria and to estimate the parameters of various functional groups. The group parameters for the functional groups present in these compounds (CH(3), CH(2), CH(3)CH, ACH, ACCH(2), CH(2)=, CH=, and OH) together with the unlike energy parameters between groups of different types are obtained from an optimal description of the pure component phase equilibria. The approach is found to describe accurately the vapor-liquid equilibria with an overall %AAD of 3.60% for the vapor

Equilibria of perceptrons for simple contingency problems.

PubMed

Dawson, Michael R W; Dupuis, Brian

2012-08-01

The contingency between cues and outcomes is fundamentally important to theories of causal reasoning and to theories of associative learning. Researchers have computed the equilibria of Rescorla-Wagner models for a variety of contingency problems, and have used these equilibria to identify situations in which the Rescorla-Wagner model is consistent, or inconsistent, with normative models of contingency. Mathematical analyses that directly compare artificial neural networks to contingency theory have not been performed, because of the assumed equivalence between the Rescorla-Wagner learning rule and the delta rule training of artificial neural networks. However, recent results indicate that this equivalence is not as straightforward as typically assumed, suggesting a strong need for mathematical accounts of how networks deal with contingency problems. One such analysis is presented here, where it is proven that the structure of the equilibrium for a simple network trained on a basic contingency problem is quite different from the structure of the equilibrium for a Rescorla-Wagner model faced with the same problem. However, these structural differences lead to functionally equivalent behavior. The implications of this result for the relationships between associative learning, contingency theory, and connectionism are discussed.

Free boundary skin current MHD (magnetohydrodynamic) equilibria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reusch, M.F.

1988-02-01

Function theoretic methods in the complex plane are used to develop simple parametric hodograph formulae which generate sharp boundary equilibria of arbitrary shape. The related method of Gorenflo and Merkel is discussed. A numerical technique for the construction of solutions, based on one of the methods is presented. A study is made of the bifurcations of an equilibrium of general form. 28 refs., 9 figs.

Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab

PubMed Central

Kawamoto, Tatsuhiko; Yoshikawa, Masako; Kumagai, Yoshitaka; Mirabueno, Ma. Hannah T.; Okuno, Mitsuru; Kobayashi, Tetsuo

2013-01-01

Slab-derived fluids play an important role in heat and material transfer in subduction zones. Dehydration and decarbonation reactions of minerals in the subducting slab have been investigated using phase equilibria and modeling of fluid flow. Nevertheless, direct observations of the fluid chemistry and pressure–temperature conditions of fluids are few. This report describes CO2-bearing saline fluid inclusions in spinel-harzburgite xenoliths collected from the 1991 Pinatubo pumice deposits. The fluid inclusions are filled with saline solutions with 5.1 ± 1.0% (wt) NaCl-equivalent magnesite crystals, CO2-bearing vapor bubbles, and a talc and/or chrysotile layer on the walls. The xenoliths contain tremolite amphibole, which is stable in temperatures lower than 830 °C at the uppermost mantle. The Pinatubo volcano is located at the volcanic front of the Luzon arc associated with subduction of warm oceanic plate. The present observation suggests hydration of forearc mantle and the uppermost mantle by slab-derived CO2-bearing saline fluids. Dehydration and decarbonation take place, and seawater-like saline fluids migrate from the subducting slab to the mantle wedge. The presence of saline fluids is important because they can dissolve more metals than pure H2O and affect the chemical evolution of the mantle wedge. PMID:23716664

Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab.

PubMed

Kawamoto, Tatsuhiko; Yoshikawa, Masako; Kumagai, Yoshitaka; Mirabueno, Ma Hannah T; Okuno, Mitsuru; Kobayashi, Tetsuo

2013-06-11

Slab-derived fluids play an important role in heat and material transfer in subduction zones. Dehydration and decarbonation reactions of minerals in the subducting slab have been investigated using phase equilibria and modeling of fluid flow. Nevertheless, direct observations of the fluid chemistry and pressure-temperature conditions of fluids are few. This report describes CO2-bearing saline fluid inclusions in spinel-harzburgite xenoliths collected from the 1991 Pinatubo pumice deposits. The fluid inclusions are filled with saline solutions with 5.1 ± 1.0% (wt) NaCl-equivalent magnesite crystals, CO2-bearing vapor bubbles, and a talc and/or chrysotile layer on the walls. The xenoliths contain tremolite amphibole, which is stable in temperatures lower than 830 °C at the uppermost mantle. The Pinatubo volcano is located at the volcanic front of the Luzon arc associated with subduction of warm oceanic plate. The present observation suggests hydration of forearc mantle and the uppermost mantle by slab-derived CO2-bearing saline fluids. Dehydration and decarbonation take place, and seawater-like saline fluids migrate from the subducting slab to the mantle wedge. The presence of saline fluids is important because they can dissolve more metals than pure H2O and affect the chemical evolution of the mantle wedge.

Contribution to modeling the viscosity Arrhenius-type equation for saturated pure fluids

NASA Astrophysics Data System (ADS)

Tian, Jianxiang; Zhang, Laibin

2016-09-01

Recently, Haj-Kacem et al. proposed an equation modeling the relationship between the two parameters of viscosity Arrhenius-type equations [Fluid Phase Equilibria 383, 11 (2014)]. The authors found that the two parameters are dependent upon each other in an exponential function form. In this paper, we reconsidered their ideas and calculated the two parameter values for 49 saturated pure fluids by using the experimental data in the NIST WebBook. Our conclusion is different with the ones of Haj-Kacem et al. We found that (the linearity shown by) the Arrhenius equation stands strongly only in low temperature range and that the two parameters of the Arrhenius equation are independent upon each other in the whole temperature range from the triple point to the critical point.

Not All Ideals are Equal: Intrinsic and Extrinsic Ideals in Relationships.

PubMed

Rodriguez, Lindsey M; Hadden, Benjamin W; Knee, C Raymond

2015-03-01

The ideal standards model suggests that greater consistency between ideal standards and actual perceptions of one's relationship predicts positive relationship evaluations; however, no research has evaluated whether this differs across types of ideals. A self-determination theory perspective was derived to test whether satisfaction of intrinsic ideals buffers the importance of extrinsic ideals. Participants (N=195) in committed relationships directly and indirectly reported the extent to which their partner met their ideal on two dimensions: intrinsic (e.g., warm, intimate) and extrinsic (e.g., attractive, successful). Relationship need fulfillment and relationship quality were also assessed. Hypotheses were largely supported, such that satisfaction of intrinsic ideals more strongly predicted relationship functioning, and satisfaction of intrinsic ideals buffered the relevance of extrinsic ideals for outcomes.

Not All Ideals are Equal: Intrinsic and Extrinsic Ideals in Relationships

PubMed Central

Rodriguez, Lindsey M.; Hadden, Benjamin W.; Knee, C. Raymond

2015-01-01

The ideal standards model suggests that greater consistency between ideal standards and actual perceptions of one’s relationship predicts positive relationship evaluations; however, no research has evaluated whether this differs across types of ideals. A self-determination theory perspective was derived to test whether satisfaction of intrinsic ideals buffers the importance of extrinsic ideals. Participants (N=195) in committed relationships directly and indirectly reported the extent to which their partner met their ideal on two dimensions: intrinsic (e.g., warm, intimate) and extrinsic (e.g., attractive, successful). Relationship need fulfillment and relationship quality were also assessed. Hypotheses were largely supported, such that satisfaction of intrinsic ideals more strongly predicted relationship functioning, and satisfaction of intrinsic ideals buffered the relevance of extrinsic ideals for outcomes. PMID:25821396

Analysis of the statistical thermodynamic model for nonlinear binary protein adsorption equilibria.

PubMed

Zhou, Xiao-Peng; Su, Xue-Li; Sun, Yan

2007-01-01

The statistical thermodynamic (ST) model was used to study nonlinear binary protein adsorption equilibria on an anion exchanger. Single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin (BSA) on DEAE Spherodex M were determined by batch adsorption experiments in 10 mM Tris-HCl buffer containing a specific NaCl concentration (0.05, 0.10, and 0.15 M) at pH 7.40. The ST model was found to depict the effect of ionic strength on the single-component equilibria well, with model parameters depending on ionic strength. Moreover, the ST model gave acceptable fitting to the binary adsorption data with the fitted single-component model parameters, leading to the estimation of the binary ST model parameter. The effects of ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories. The effective charge of protein in adsorption phase can be separately calculated from the two categories of the model parameters, and the values obtained from the two methods are consistent. The results demonstrate the utility of the ST model for describing nonlinear binary protein adsorption equilibria.

Methods of use for sensor based fluid detection devices

NASA Technical Reports Server (NTRS)

Lewis, Nathan S. (Inventor)

2001-01-01

Methods of use and devices for detecting analyte in fluid. A system for detecting an analyte in a fluid is described comprising a substrate having a sensor comprising a first organic material and a second organic material where the sensor has a response to permeation by an analyte. A detector is operatively associated with the sensor. Further, a fluid delivery appliance is operatively associated with the sensor. The sensor device has information storage and processing equipment, which is operably connected with the device. This device compares a response from the detector with a stored ideal response to detect the presence of analyte. An integrated system for detecting an analyte in a fluid is also described where the sensing device, detector, information storage and processing device, and fluid delivery device are incorporated in a substrate. Methods for use for the above system are also described where the first organic material and a second organic material are sensed and the analyte is detected with a detector operatively associated with the sensor. The method provides for a device, which delivers fluid to the sensor and measures the response of the sensor with the detector. Further, the response is compared to a stored ideal response for the analyte to determine the presence of the analyte. In different embodiments, the fluid measured may be a gaseous fluid, a liquid, or a fluid extracted from a solid. Methods of fluid delivery for each embodiment are accordingly provided.

A Multistep Equilibria-Redox-Complexation Demonstration to Illustrate Le Chatelier's Principle.

ERIC Educational Resources Information Center

Berger, Tomas G.; Mellon, Edward K.

1996-01-01

Describes a process that can be used to illustrate a number of chemical principles including Le Chatelier's principle, redox chemistry, equilibria versus steady state situations, and solubility of species. (JRH)

Integrated Modeling of Time Evolving 3D Kinetic MHD Equilibria and NTV Torque

NASA Astrophysics Data System (ADS)

Logan, N. C.; Park, J.-K.; Grierson, B. A.; Haskey, S. R.; Nazikian, R.; Cui, L.; Smith, S. P.; Meneghini, O.

2016-10-01

New analysis tools and integrated modeling of plasma dynamics developed in the OMFIT framework are used to study kinetic MHD equilibria evolution on the transport time scale. The experimentally observed profile dynamics following the application of 3D error fields are described using a new OMFITprofiles workflow that directly addresses the need for rapid and comprehensive analysis of dynamic equilibria for next-step theory validation. The workflow treats all diagnostic data as fundamentally time dependent, provides physics-based manipulations such as ELM phase data selection, and is consistent across multiple machines - including DIII-D and NSTX-U. The seamless integration of tokamak data and simulation is demonstrated by using the self-consistent kinetic EFIT equilibria and profiles as input into 2D particle, momentum and energy transport calculations using TRANSP as well as 3D kinetic MHD equilibrium stability and neoclassical transport modeling using General Perturbed Equilibrium Code (GPEC). The result is a smooth kinetic stability and NTV torque evolution over transport time scales. Work supported by DE-AC02-09CH11466.

Finite-beta equilibria for Wendelstein 7-X configurations using the Princeton Iterative Equilibrium Solver code

NASA Astrophysics Data System (ADS)

Arndt, S.; Merkel, P.; Monticello, D. A.; Reiman, A. H.

1999-04-01

Fixed- and free-boundary equilibria for Wendelstein 7-X (W7-X) [W. Lotz et al., Plasma Physics and Controlled Nuclear Fusion Research 1990 (Proc. 13th Int. Conf. Washington, DC, 1990), (International Atomic Energy Agency, Vienna, 1991), Vol. 2, p. 603] configurations are calculated using the Princeton Iterative Equilibrium Solver (PIES) [A. H. Reiman et al., Comput. Phys. Commun., 43, 157 (1986)] to deal with magnetic islands and stochastic regions. Usually, these W7-X configurations require a large number of iterations for PIES convergence. Here, two methods have been successfully tested in an attempt to decrease the number of iterations needed for convergence. First, periodic sequences of different blending parameters are used. Second, the initial guess is vastly improved by using results of the Variational Moments Equilibrium Code (VMEC) [S. P. Hirshmann et al., Phys. Fluids 26, 3553 (1983)]. Use of these two methods have allowed verification of the Hamada condition and tendency of "self-healing" of islands has been observed.

Predominance Diagrams, a Useful Tool for the Correlation of the Precipitation-Solubility Equilibrium with Other Ionic Equilibria

ERIC Educational Resources Information Center

Pereira, Constantino Fernandez; Alcalde, Manuel; Villegas, Rosario; Vale, Jose

2007-01-01

The four types of ionic equilibria--acid-base, redox, precipitation, and complexation--have certain similarities, which has led some authors to develop a unified treatment of them. These authors have highlighted the common aspects and tried to find a systemization of the equilibria that would facilitate learning them. In this unified treatment,…

Guiding principles of fluid and volume therapy.

PubMed

Aditianingsih, Dita; George, Yohanes W H

2014-09-01

Fluid therapy is a core concept in the management of perioperative and critically ill patients for maintenance of intravascular volume and organ perfusion. Recent evidence regarding the vascular barrier and its role in terms of vascular leakage has led to a new concept for fluid administration. The choice of fluid used should be based on the fluid composition and the underlying pathophysiology of the patient. Avoidance of both hypo- and hypervolaemia is essential when treating circulatory failure. In daily practice, the assessment of individual thresholds in order to optimize cardiac preload and avoid hypovolaemia or deleterious fluid overload remains a challenge. Liberal versus restrictive fluid management has been challenged by recent evidence, and the ideal approach appears to be goal-directed fluid therapy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Solid-phase equilibria on Pluto's surface

NASA Astrophysics Data System (ADS)

Tan, Sugata P.; Kargel, Jeffrey S.

2018-03-01

Pluto's surface is covered by volatile ices that are in equilibrium with the atmosphere. Multicomponent phase equilibria may be calculated using a thermodynamic equation of state and, without additional assumptions, result in methane-rich and nitrogen-rich solid phases. The former is formed at temperature range between the atmospheric pressure-dependent sublimation and condensation points, while the latter is formed at temperatures lower than the sublimation point. The results, calculated for the observed 11 μbar atmospheric pressure and composition, are consistent with recent work derived from observations by New Horizons.

Graphic Representation of Carbon Dioxide Equilibria in Biological Systems.

ERIC Educational Resources Information Center

Kindig, Neal B.; Filley, Giles F.

1983-01-01

The log C-pH diagram is a useful means of displaying quantitatively the many variables (including temperature) that determine acid-base equilibria in biological systems. Presents the diagram as extended to open/closed biological systems and derives a new water-ion balance method for determining equilibrium pH. (JN)

Protonation linked equilibria and apparent affinity constants: the thermodynamic profile of the alpha-chymotrypsin-proflavin interaction.

PubMed

Bruylants, Gilles; Wintjens, René; Looze, Yvan; Redfield, Christina; Bartik, Kristin

2007-12-01

Protonation/deprotonation equilibria are frequently linked to binding processes involving proteins. The presence of these thermodynamically linked equilibria affects the observable thermodynamic parameters of the interaction (K(obs), DeltaH(obs)(0) ). In order to try and elucidate the energetic factors that govern these binding processes, a complete thermodynamic characterisation of each intrinsic equilibrium linked to the complexation event is needed and should furthermore be correlated to structural information. We present here a detailed study, using NMR and ITC, of the interaction between alpha-chymotrypsin and one of its competitive inhibitors, proflavin. By performing proflavin titrations of the enzyme, at different pH values, we were able to highlight by NMR the effect of the complexation of the inhibitor on the ionisable residues of the catalytic triad of the enzyme. Using ITC we determined the intrinsic thermodynamic parameters of the different equilibria linked to the binding process. The possible driving forces of the interaction between alpha-chymotrypsin and proflavin are discussed in the light of the experimental data and on the basis of a model of the complex. This study emphasises the complementarities between ITC and NMR for the study of binding processes involving protonation/deprotonation equilibria.

Sex Education and Ideals

ERIC Educational Resources Information Center

de Ruyter, Doret J.; Spiecker, Ben

2008-01-01

This article argues that sex education should include sexual ideals. Sexual ideals are divided into sexual ideals in the strict sense and sexual ideals in the broad sense. It is argued that ideals that refer to the context that is deemed to be most ideal for the gratification of sexual ideals in the strict sense are rightfully called sexual…

Substituent Effects on Keto-Enol Equilibria Using NMR Spectroscopy

ERIC Educational Resources Information Center

Manbeck, Kimberly A.; Boaz, Nicholas C.; Bair, Nathaniel C.; Sanders, Allix M. S.; Marsh, Anderson L.

2011-01-01

In this extension to a classic physical chemistry experiment, students record the proton nuclear magnetic resonance spectra of the [beta]-diketones 2,4-pentanedione, 3-methyl-2,4-pentanedione, and 3-chloro-2,4-pentanedione to investigate the effect of substituents on keto-enol tautomerization equilibria. From the integrated intensities of keto and…

Fluorite solubility equilibria in selected geothermal waters

USGS Publications Warehouse

Nordstrom, D. Kirk; Jenne, E.A.

1977-01-01

Calculation of chemical equilibria in 351 hot springs and surface waters from selected geothermal areas in the western United States indicate that the solubility of the mineral fluorite, CaF2, provides an equilibrium control on dissolved fluoride activity. Waters that are undersaturated have undergone dilution by non-thermal waters as shown by decreased conductivity and temperature values, and only 2% of the samples are supersaturated by more than the expected error. Calculations also demonstrate that simultaneous chemical equilibria between the thermal waters and calcite as well as fluorite minerals exist under a variety of conditions. Testing for fluorite solubility required a critical review of the thermodynamic data for fluorite. By applying multiple regression of a mathematical model to selected published data we have obtained revised estimates of the pK (10,96), ??Gof (-280.08 kcal/mole), ??Hof (-292.59 kcal/mole), S?? (16.39 cal/deg/mole) and CoP (16.16 cal/deg/mole) for CaF2 at 25??C and 1 atm. Association constants and reaction enthalpies for fluoride complexes with boron, calcium and iron are included in this review. The excellent agreement between the computer-based activity products and the revised pK suggests that the chemistry of geothermal waters may also be a guide to evaluating mineral solubility data where major discrepancies are evident. ?? 1977.

Generating perfect fluid spheres in general relativity

NASA Astrophysics Data System (ADS)

Boonserm, Petarpa; Visser, Matt; Weinfurtner, Silke

2005-06-01

Ever since Karl Schwarzschild’s 1916 discovery of the spacetime geometry describing the interior of a particular idealized general relativistic star—a static spherically symmetric blob of fluid with position-independent density—the general relativity community has continued to devote considerable time and energy to understanding the general-relativistic static perfect fluid sphere. Over the last 90 years a tangle of specific perfect fluid spheres has been discovered, with most of these specific examples seemingly independent from each other. To bring some order to this collection, in this article we develop several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. These transformation theorems sometimes lead to unexpected connections between previously known perfect fluid spheres, sometimes lead to new previously unknown perfect fluid spheres, and in general can be used to develop a systematic way of classifying the set of all perfect fluid spheres.

Phase equilibria constraints on the chemical and physical evolution of the campanian ignimbrite

USGS Publications Warehouse

Fowler, S.J.; Spera, F.J.; Bohrson, W.A.; Belkin, H.E.; de Vivo, B.

2007-01-01

The Campanian Ignimbrite is a > 200 km3 trachyte-phonolite pyroclastic deposit that erupted at 39.3 ?? 0.1 ka within the Campi Flegrei west of Naples, Italy. Here we test the hypothesis that Campanian Ignimbrite magma was derived by isobaric crystal fractionation of a parental basaltic trachyandesitic melt that reacted and came into local equilibrium with small amounts (5-10 wt%) of crustal rock (skarns and foid-syenites) during crystallization. Comparison of observed crystal and magma compositions with results of phase equilibria assimilation-fractionation simulations (MELTS) is generally very good. Oxygen fugacity was approximately buffered along QFM+1 (where QFM is the quartz-fayalite-magnetite buffer) during isobaric fractionation at 0.15 GPa (???6 km depth). The parental melt, reconstructed from melt inclusion and host clinopyroxene compositions, is found to be basaltic trachyandesite liquid (51.1 wt% SiO2, 9.3 wt% MgO, 3 wt% H2O). A significant feature of phase equilibria simulations is the existence of a pseudo-invariant temperature, ???883??C, at which the fraction of melt remaining in the system decreases abruptly from ???0.5 to < 0.1. Crystallization at the pseudo-invariant point leads to abrupt changes in the composition, properties (density, dissolved water content), and physical state (viscosity, volume fraction fluid) of melt and magma. A dramatic decrease in melt viscosity (from 1700 Pa s to ???200 Pa s), coupled with a change in the volume fraction of water in magma (from ??? 0.1 to 0.8) and a dramatic decrease in melt and magma density acted as a destabilizing eruption trigger. Thermal models suggest a timescale of ??? 200 kyr from the beginning of fractionation until eruption, leading to an apparent rate of evolved magma generation of about 10-3 km3/year. In situ crystallization and crystal settling in density-stratified regions, as well as in convectively mixed, less evolved subjacent magma, operate rapidly enough to match this apparent

Impact of an Exhaust Throat on Semi-Idealized Rotating Detonation Engine Performance

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.

2016-01-01

A computational fluid dynamic (CFD) model of a rotating detonation engine (RDE) is used to examine the impact of an exhaust throat (i.e. a constriction) on performance. The model simulates an RDE which is premixed, adiabatic, inviscid, and which contains an inlet valve that prevents backflow from the high pressure region directly behind the rotating detonation. Performance is assessed in terms of ideal net specific impulse which is computed on the assumption of lossless expansion of the working fluid to the ambient pressure through a notional diverging nozzle section downstream of the throat. Such a semi-idealized analysis, while not real-world, allows the effect of the throat to be examined in isolation from, rather than coupled to (as it actually is) various loss mechanisms. For the single Mach 1.4 flight condition considered, it is found that the addition of a throat can yield a 9.4 percent increase in specific impulse. However, it is also found that when the exit throat restriction gets too small, an unstable type of operation ensues which eventually leads to the detonation failing. This behavior is found to be somewhat mitigated by the addition of an RDE inlet restriction across which there is an aerodynamic loss. Remarkably, this loss is overcome by the benefits of the further exhaust restrictions allowed. The end result is a configuration with a 10.3 percent improvement in ideal net specific thrust.

Impact of an Exhaust Throat on Semi-Idealized Rotating Detonation Engine Performance

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.

2016-01-01

A computational fluid dynamic (CFD) model of a rotating detonation engine (RDE) is used to examine the impact of an exhaust throat (i.e., a constriction) on performance. The model simulates an RDE which is premixed, adiabatic, inviscid, and which contains an inlet valve that prevents backflow from the high pressure region directly behind the rotating detonation. Performance is assessed in terms of ideal net specific impulse which is computed on the assumption of lossless expansion of the working fluid to the ambient pressure through a notional diverging nozzle section downstream of the throat. Such a semi-idealized analysis, while not real-world, allows the effect of the throat to be examined in isolation from, rather than coupled to (as it actually is) various loss mechanisms. For the single Mach 1.4 flight condition considered, it is found that the addition of a throat can yield a 9.4 percent increase in specific impulse. However, it is also found that when the exit throat restriction gets too small, an unstable type of operation ensues which eventually leads to the detonation failing. This behavior is found to be somewhat mitigated by the addition of an RDE inlet restriction across which there is an aerodynamic loss. Remarkably, this loss is overcome by the benefits of the further exhaust restrictions allowed. The end result is a configuration with a 10.3 percent improvement in ideal net specific thrust.

Thermodynamic models for vapor-liquid equilibria of nitrogen + oxygen + carbon dioxide at low temperatures

NASA Astrophysics Data System (ADS)

Vrabec, Jadran; Kedia, Gaurav Kumar; Buchhauser, Ulrich; Meyer-Pittroff, Roland; Hasse, Hans

2009-02-01

For the design and optimization of CO 2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N 2 + O 2 + CO 2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N 2 and O 2 in CO 2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO 2-rich region.

The nucleation rate surfaces design over diagram of phase equilibria and their applications for computational chemistry

NASA Astrophysics Data System (ADS)

Anisimov, M. P.

2016-12-01

One can find in scientific literature a pretty fresh idea of the nucleation rate surfaces design over the diagrams of phase equilibria. That idea looks like profitable for the nucleation theory development and for various practical applications where predictions of theory have no high enough accuracy for today. The common thermodynamics has no real ability to predict parameters of the first order phase transition. Nucleation experiment can be provided in very local nucleation conditions even the nucleation takes place from the critical line (in two-component case) down to the absolute zero temperature limit and from zero nucleation rates at phase equilibria up to the spinodal conditions. Theory predictions have low reliability as a rule. The computational chemistry has chance to make solution of that problem easier when a set of the used axiomatic statements will adapt enough progressive assumptions [1]. Semiempirical design of the nucleation rate surfaces over diagrams of phase equilibria have a potential ability to provide a reasonable quality information on nucleation rate for each channel of nucleation. Consideration and using of the nucleation rate surface topologies to optimize synthesis of a given phase of the target material can be available when data base on nucleation rates over diagrams of phase equilibria will be created.

Surface currents on the plasma-vacuum interface in MHD equilibria

NASA Astrophysics Data System (ADS)

Hanson, James D.

2016-10-01

The VMEC non-axisymmetric MHD equilibrium code can compute free-boundary equilibria. Since VMEC assumes that magnetic fields within the plasma form closed and nested flux surfaces, the plasma-vacuum interface is a flux surface, and the total magnetic field there has no normal component. VMEC imposes this condition of zero normal field using the potential formulation of Merkel, and solves a Neumann problem for the magnetic potential in the exterior region. This boundary condition necessarily admits the possibility of a surface current on the plasma-vacuum interface. While this current may be small in MHD equilibrium, this current may be readily computed in terms of a magnetic potential in both the interior and exterior regions. Examples of the surface current for VMEC equilibria will be shown. This material is based upon work supported by Auburn University and the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG02-03ER54692.

Roto-orbital dynamics of a triaxial rigid body around a sphere. Relative equilibria and stability

NASA Astrophysics Data System (ADS)

Crespo, F.; Ferrer, S.

2018-06-01

We study the roto-orbital motion of a triaxial rigid body around a sphere, which is assumed to be much more massive than the triaxial body. The associated dynamics of this system, which consists of a normalized Hamiltonian with respect to the fast angles (partial averaging), is investigated making use of variables referred to the total angular momentum. The first order approximation of this model is integrable. We carry out the analysis of the relative equilibria, which hinges principally in the dihedral angle between the orbital and rotational planes and the ratio among the moments of inertia ρ = (B - A) / (2 C - B - A) . In particular, the dynamics of the body frame, though formally given by the classical Euler equations, experiences changes of stability in the principal directions related to the roto-orbital coupling. When ρ = 1 / 3 , we find a family of relative equilibria connected to the unstable equilibria of the free rigid body.

Dynamo Effects in Magnetized Ideal Plasma Cosmologies

NASA Astrophysics Data System (ADS)

Kleidis, Kostas; Kuiroukidis, Apostolos; Papadopoulos, Demetrios; Vlahos, Loukas

The excitation of cosmological perturbations in an anisotropic cosmological model and in the presence of a homogeneous magnetic field has been studied, using the ideal magnetohydrodynamic (MHD) equations. In this case, the system of partial differential equations which governs the evolution of the magnetized cosmological perturbations can be solved analytically. Our results verify that fast-magnetosonic modes propagating normal to the magnetic field, are excited. But, what is most important, is that, at late times, the magnetic-induction contrast (δB/B) grows, resulting in the enhancement of the ambient magnetic field. This process can be particularly favored by condensations, formed within the plasma fluid due to gravitational instabilities.

Exotic equilibria of Harary graphs and a new minimum degree lower bound for synchronization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canale, Eduardo A., E-mail: ecanale@pol.una.py; Monzón, Pablo, E-mail: monzon@fing.edu.uy

2015-02-15

This work is concerned with stability of equilibria in the homogeneous (equal frequencies) Kuramoto model of weakly coupled oscillators. In 2012 [R. Taylor, J. Phys. A: Math. Theor. 45, 1–15 (2012)], a sufficient condition for almost global synchronization was found in terms of the minimum degree–order ratio of the graph. In this work, a new lower bound for this ratio is given. The improvement is achieved by a concrete infinite sequence of regular graphs. Besides, non standard unstable equilibria of the graphs studied in Wiley et al. [Chaos 16, 015103 (2006)] are shown to exist as conjectured in that work.

Invariant and partially-invariant solutions of the equations describing a non-stationary and isentropic flow for an ideal and compressible fluid in (3 + 1) dimensions

NASA Astrophysics Data System (ADS)

Grundland, A. M.; Lalague, L.

1996-04-01

This paper presents a new method of constructing, certain classes of solutions of a system of partial differential equations (PDEs) describing the non-stationary and isentropic flow for an ideal compressible fluid. A generalization of the symmetry reduction method to the case of partially-invariant solutions (PISs) has been formulated. We present a new algorithm for constructing PISs and discuss in detail the necessary conditions for the existence of non-reducible PISs. All these solutions have the defect structure 0305-4470/29/8/019/img1 and are computed from four-dimensional symmetric subalgebras. These theoretical considerations are illustrated by several examples. Finally, some new classes of invariant solutions obtained by the symmetry reduction method are included. These solutions represent central, conical, rational, spherical, cylindrical and non-scattering double waves.

Liquid-vapor phase equilibria and the thermodynamic properties of 2-methylpropanol- n-alkyl propanoate solutions

NASA Astrophysics Data System (ADS)

Suntsov, Yu. K.; Goryunov, V. A.; Chuikov, A. M.; Meshcheryakov, A. V.

2016-08-01

The boiling points of solutions of five binary systems are measured via ebulliometry in the pressure range of 2.05-103.3 kPa. Equilibrium vapor phase compositions, the values of the excess Gibbs energies, enthalpies, and entropies of solution of these systems are calculated. Patterns in the changes of phase equilibria and thermodynamic properties of solutions are established, depending on the compositions and temperatures of the systems. Liquid-vapor equilibria in the systems are described using the equations of Wilson and the NRTL (Non-Random Two-Liquid Model).

Experimental investigation of the phase equilibria in the carbon dioxide-propane-3 M MDEA system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jou, F.Y.; Mather, A.E.; Otto, F.D.

1995-07-01

The treating of liquefied petroleum gas (LPG) to remove carbon dioxide and hydrogen sulfide using aqueous alkanolamine solutions is an important aspect of gas processing. One of the amines used in the natural gas industry is methyldiethanolamine (MDEA). Measurements of the phase equilibria in the carbon dioxide-propane-3 M MDEA system have been made at 25 and 40 C at pressures up to 15.5 MPa. Vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibria were determined. The vapor-liquid equilibrium data were compared with the model of Deshmukh and Mather.

The Motion and Control of a Chaplygin Sleigh with Internal Shape in an Ideal Fluid

NASA Astrophysics Data System (ADS)

Barot, Christopher

In this dissertation we will examine a nonholonomic system with Lie group symmetry: the Chaplygin sleigh coupled to an oscillator moving through a potential fluid in two dimensions. This example is chosen to illustrate several general features. The sleigh system in the plane has SE(2) symmetry. This group symmetry will be used to separate the dynamics of the system into those along the group directions and those not. The oscillator motion is not along the group and so acts as an additional configuration space coordinate that plays the role of internal "shape". The potential fluid serves as an interactive environment for the sleigh. The interaction between the fluid and sleigh depends not only on the sleigh body shape and size but also on its motion. The motion of the sleigh causes motion in the surrounding fluid and vice-versa. Since the sleigh body is coupled to the oscillator, the oscillator will have indirect interaction with the fluid. This oscillator serves as internal shape and interacts with the external environment of the sleigh through its coupling to the sleigh body and the nonholonomic constraint; it will be shown that this interaction can produce a variety of types of motion depending on the sleigh geometry. In particular, when the internal shape of the system is actively controlled, it will be proven that the sleigh can be steered through the plane towards any desired position. In this way the sleigh-fluid-oscillator system will demonstrate how a rigid body can be steered through an interactive environment by controlling things wholly within the body itself and without use of external thrust.

Crystallization of pure anhydrous polymorphs of carbamazepine by solution enhanced dispersion with supercritical fluids (SEDS).

PubMed

Edwards, A D; Shekunov, B Y; Kordikowski, A; Forbes, R T; York, P

2001-08-01

Pure anhydrous polymorphs of carbamazepine were prepared by solution-enhanced dispersion with supercritical fluids (SEDS). Crystallization of the polymorphs was studied. Mechanisms are proposed that consider the thermodynamics of carbamazepine, supersaturation in the SEDS process, and the binary phase equilibria of organic solvents and the carbon dioxide antisolvent. alpha-Carbamazepine was crystallized at high supersaturations and low temperatures, beta-carbamazepine crystallized from a methanol-carbon dioxide phase split, and gamma-carbamazepine crystallized via nucleation at high temperatures and low supersaturation. Copyright 2001 Wiley-Liss, Inc.

New integrable models and analytical solutions in f (R ) cosmology with an ideal gas

NASA Astrophysics Data System (ADS)

Papagiannopoulos, G.; Basilakos, Spyros; Barrow, John D.; Paliathanasis, Andronikos

2018-01-01

In the context of f (R ) gravity with a spatially flat FLRW metric containing an ideal fluid, we use the method of invariant transformations to specify families of models which are integrable. We find three families of f (R ) theories for which new analytical solutions are given and closed-form solutions are provided.

Finding Bounded Rational Equilibria. Part 2; Alternative Lagrangians and Uncountable Move Spaces

NASA Technical Reports Server (NTRS)

Wolpert, David H.

2004-01-01

A long-running difficulty with conventional game theory has been how to modify it to accommodate the bounded rationality characterizing all real-world players. A recurring issue in statistical physics is how best to approximate joint probability distributions with decoupled (and therefore far more tractable) distributions. It has recently been shown that the same information theoretic mathematical structure, known as Probability Collectives (PC) underlies both issues. This relationship between statistical physics and game theory allows techniques and insights &om the one field to be applied to the other. In particular, PC provides a formal model-independent definition of the degree of rationality of a player and of bounded rationality equilibria. This pair of papers extends previous work on PC by introducing new computational approaches to effectively find bounded rationality equilibria of common-interest (team) games.

The energy density distribution of an ideal gas and Bernoulli’s equations

NASA Astrophysics Data System (ADS)

Santos, Leonardo S. F.

2018-05-01

This work discusses the energy density distribution in an ideal gas and the consequences of Bernoulli’s equation and the corresponding relation for compressible fluids. The aim of this work is to study how Bernoulli’s equation determines the energy flow in a fluid, although Bernoulli’s equation does not describe the energy density itself. The model from molecular dynamic considerations that describes an ideal gas at rest with uniform density is modified to explore the gas in motion with non-uniform density and gravitational effects. The difference between the component of the speed of a particle that is parallel to the gas speed and the gas speed itself is called ‘parallel random speed’. The pressure from the ‘parallel random speed’ is denominated as parallel pressure. The modified model predicts that the energy density is the sum of kinetic and potential gravitational energy densities plus two terms with static and parallel pressures. The application of Bernoulli’s equation and the corresponding relation for compressible fluids in the energy density expression has resulted in two new formulations. For incompressible and compressible gas, the energy density expressions are written as a function of stagnation, static and parallel pressures, without any dependence on kinetic or gravitational potential energy densities. These expressions of the energy density are the main contributions of this work. When the parallel pressure was uniform, the energy density distribution for incompressible approximation and compressible gas did not converge to zero for the limit of null static pressure. This result is rather unusual because the temperature tends to zero for null pressure. When the gas was considered incompressible and the parallel pressure was equal to static pressure, the energy density maintained this unusual behaviour with small pressures. If the parallel pressure was equal to static pressure, the energy density converged to zero for the limit of the

A self-consistent treatment of a fluid in an external potential

NASA Astrophysics Data System (ADS)

Boudh-Hir, M.-E.

A simple fluid of particles near a repulsive structureless wall can be approximated by an identical fluid interacting with an ideal wall. The expansion in powers of the Andersen-Weeks-Chandler (AWC) blip function is used. Lado's criterion, which permits a self-consistent approximation, is extended to the surface case.

Efficiency reduction and pseudo-convergence in replica exchange sampling of peptide folding unfolding equilibria

NASA Astrophysics Data System (ADS)

Denschlag, Robert; Lingenheil, Martin; Tavan, Paul

2008-06-01

Replica exchange (RE) molecular dynamics (MD) simulations are frequently applied to sample the folding-unfolding equilibria of β-hairpin peptides in solution, because efficiency gains are expected from this technique. Using a three-state Markov model featuring key aspects of β-hairpin folding we show that RE simulations can be less efficient than conventional techniques. Furthermore we demonstrate that one is easily seduced to erroneously assign convergence to the RE sampling, because RE ensembles can rapidly reach long-lived stationary states. We conclude that typical REMD simulations covering a few tens of nanoseconds are by far too short for sufficient sampling of β-hairpin folding-unfolding equilibria.

Three dimensional boundary displacement due to stable ideal kink modes excited by external n = 2 magnetic perturbations

NASA Astrophysics Data System (ADS)

Willensdorfer, M.; Strumberger, E.; Suttrop, W.; Dunne, M.; Fischer, R.; Birkenmeier, G.; Brida, D.; Cavedon, M.; Denk, S. S.; Igochine, V.; Giannone, L.; Kirk, A.; Kirschner, J.; Medvedeva, A.; Odstrčil, T.; Ryan, D. A.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

2017-11-01

In low-collisionality (ν\\star) scenarios exhibiting mitigation of edge localized mode (ELMs), stable ideal kink modes at the edge are excited by externally applied magnetic perturbation (MP)-fields. In ASDEX Upgrade these modes can cause three-dimensional (3D) boundary displacements up to the centimeter range. These displacements have been measured using toroidally localized high resolution diagnostics and rigidly rotating n=2 MP-fields with various applied poloidal mode spectra. These measurements are compared to non-linear 3D ideal magnetohydrodynamics (MHD) equilibria calculated by VMEC. Comprehensive comparisons have been conducted, which consider for instance plasma movements due to the position control system, attenuation due to internal conductors and changes in the edge pressure profiles. VMEC accurately reproduces the amplitude of the displacement and its dependencies on the applied poloidal mode spectra. Quantitative agreement is found around the low field side (LFS) midplane. The response at the plasma top is qualitatively compared. The measured and predicted displacements at the plasma top maximize when the applied spectra is optimized for ELM-mitigation. The predictions from the vacuum modeling generally fails to describe the displacement at the LFS midplane as well as at the plasma top. When the applied mode spectra is set to maximize the displacement, VMEC and the measurements clearly surpass the predictions from the vacuum modeling by a factor of four. Minor disagreements between VMEC and the measurements are discussed. This study underlines the importance of the stable ideal kink modes at the edge for the 3D boundary displacement in scenarios relevant for ELM-mitigation.

Surface currents on the plasma-vacuum interface in MHD equilibria

NASA Astrophysics Data System (ADS)

Hanson, James

2017-10-01

The VMEC non-axisymmetric MHD equilibrium code can compute free-boundary equilibria. Since VMEC assumes that magnetic fields within the plasma form closed and nested flux surfaces, the plasma-vacuum interface is a flux surface, and the total magnetic field there has no normal component. VMEC imposes this condition of zero normal field using the potential formulation of Merkel, and solves a Neumann problem for the magnetic potential in the exterior region. This boundary condition necessarily admits the possibility of a surface current on the interface. While this surface current may be small in MHD equilibrium, it is readily computed in terms of the magnetic potentials in both the interior and exterior regions, evaluated on the surface. If only the external magnetic potential is known (as in VMEC), then the surface current can be computed from the discontinuity of the tangential field across the interface. Examples of the surface current for VMEC equilibria will be shown for a zero-pressure stellarator equilibrium. Field-line following of the vacuum magnetic field shows magnetic islands within the plasma region.

Nonlinear Two Fluid and Kinetic ELM Simulations

NASA Astrophysics Data System (ADS)

Strauss, H. R.; Sugiyama, L.; Chang, C. S.; Ku, S.; Hientzsch, B.; Breslau, J.; Park, W.; Samtaney, R.; Adams, M.; Jardin, S.

2006-04-01

Simulations of ELMs using dissipative MHD, two fluid MHD, and neoclassical kinetic physics models are being carried out using the M3D code [1]. Resistive MHD simulations of nonlinear edge pressure and current driven instabilities have been performed, initialized with realistic DIIID equilibria. Simulations show the saturation of the modes and relaxation of equilbrium profiles. Linear simulations including two fluid effects show the stabilization of toroidal mode number n = 10 modes, when the Hall parameter H, the ratio of ion skin depth to major radius, exceeds a threshhold. Nonlinear simulations are being done including gyroviscous stabilization. Kinetic effects are incorporated by coupling with the XGC code [2], which is able to simulate the edge plasma density and pressure pedestal buildup. These profiles are being used to initialize M3D simulations of an ELM crash and pedestal relaxation. The goal is to simulate an ELM cycle. [1] Park, W., Belova, E.V., Fu, G.Y., Tang, X.Z., Strauss, H.R., Sugiyama, L.E., Phys. Plas. 6, 1796 (1999).[2] Chang, C.S., Ku, S., and Weitzner, H., Phys. Plas. 11, 2649 (2004)

Collisionless current sheet equilibria

NASA Astrophysics Data System (ADS)

Neukirch, T.; Wilson, F.; Allanson, O.

2018-01-01

Current sheets are important for the structure and dynamics of many plasma systems. In space and astrophysical plasmas they play a crucial role in activity processes, for example by facilitating the release of magnetic energy via processes such as magnetic reconnection. In this contribution we will focus on collisionless plasma systems. A sensible first step in any investigation of physical processes involving current sheets is to find appropriate equilibrium solutions. The theory of collisionless plasma equilibria is well established, but over the past few years there has been a renewed interest in finding equilibrium distribution functions for collisionless current sheets with particular properties, for example for cases where the current density is parallel to the magnetic field (force-free current sheets). This interest is due to a combination of scientific curiosity and potential applications to space and astrophysical plasmas. In this paper we will give an overview of some of the recent developments, discuss their potential applications and address a number of open questions.

Properties of two-fluid flowing equilibria observed in double-pulsing coaxial helicity injection on HIST

NASA Astrophysics Data System (ADS)

Kanki, T.; Nagata, M.

2013-10-01

Multi-pulsing coaxial helicity injection (M-CHI) method which aims to achieve both quasi-steady sustainment and good confinement has been proposed as a refluxing scenario of the CHI. To explore the usefulness of the M-CHI for spherical torus (ST) configurations, the double-pulsing operations have been carried out in the HIST, verifying the flux amplification and the formation of the closed flux surfaces after the second CHI pulse. The purpose of this study is to investigate the properties of the magnetic field and plasma flow structures during the sustainment by comparing the results of plasma flow, density, and magnetic fields measurements with those of two-fluid equilibrium calculations. The two-fluid flowing equilibrium model which is described by a pair of generalized Grad-Shafranov equations for ion and electron surface variables and Bernoulli equations for density is applied to reconstruct the ST configuration with poloidal flow shear observed in the HIST. Due to the negative steep density gradient in high field side, the toroidal field has a diamagnetic profile (volume average beta, < β > = 68 %) in the central open flux column region. The ion flow velocity with strong flow shear from the separatrix in the inboard side to the core region is the opposite direction to the electron flow velocity due to the diamagentic drift through the density gradient. The electric field is relatively small in the whole region, and thus the Lorentz force nearly balances with the two-fluid effect which is particularly significant in a region with the steep density gradient due to the ion and electron diamagnetic drifts.

Fluid mechanics of heart valves.

PubMed

Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

2004-01-01

Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

Kinetic Simulations of the Lowest-order Unstable Mode of Relativistic Magnetostatic Equilibria

NASA Astrophysics Data System (ADS)

Nalewajko, Krzysztof; Zrake, Jonathan; Yuan, Yajie; East, William E.; Blandford, Roger D.

2016-08-01

We present the results of particle-in-cell numerical pair plasma simulations of relativistic two-dimensional magnetostatic equilibria known as the “Arnold-Beltrami-Childress” fields. In particular, we focus on the lowest-order unstable configuration consisting of two minima and two maxima of the magnetic vector potential. Breaking of the initial symmetry leads to exponential growth of the electric energy and to the formation of two current layers, which is consistent with the picture of “X-point collapse” first described by Syrovatskii. Magnetic reconnection within the layers heats a fraction of particles to very high energies. After the saturation of the linear instability, the current layers are disrupted and the system evolves chaotically, diffusing the particle energies in a stochastic second-order Fermi process, leading to the formation of power-law energy distributions. The power-law slopes harden with the increasing mean magnetization, but they are significantly softer than those produced in simulations initiated from Harris-type layers. The maximum particle energy is proportional to the mean magnetization, which is attributed partly to the increase of the effective electric field and partly to the increase of the acceleration timescale. We describe in detail the evolving structure of the dynamical current layers and report on the conservation of magnetic helicity. These results can be applied to highly magnetized astrophysical environments, where ideal plasma instabilities trigger rapid magnetic dissipation with efficient particle acceleration and flares of high-energy radiation.

KINETIC SIMULATIONS OF THE LOWEST-ORDER UNSTABLE MODE OF RELATIVISTIC MAGNETOSTATIC EQUILIBRIA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nalewajko, Krzysztof; Zrake, Jonathan; Yuan, Yajie

2016-08-01

We present the results of particle-in-cell numerical pair plasma simulations of relativistic two-dimensional magnetostatic equilibria known as the “Arnold–Beltrami–Childress” fields. In particular, we focus on the lowest-order unstable configuration consisting of two minima and two maxima of the magnetic vector potential. Breaking of the initial symmetry leads to exponential growth of the electric energy and to the formation of two current layers, which is consistent with the picture of “X-point collapse” first described by Syrovatskii. Magnetic reconnection within the layers heats a fraction of particles to very high energies. After the saturation of the linear instability, the current layers aremore » disrupted and the system evolves chaotically, diffusing the particle energies in a stochastic second-order Fermi process, leading to the formation of power-law energy distributions. The power-law slopes harden with the increasing mean magnetization, but they are significantly softer than those produced in simulations initiated from Harris-type layers. The maximum particle energy is proportional to the mean magnetization, which is attributed partly to the increase of the effective electric field and partly to the increase of the acceleration timescale. We describe in detail the evolving structure of the dynamical current layers and report on the conservation of magnetic helicity. These results can be applied to highly magnetized astrophysical environments, where ideal plasma instabilities trigger rapid magnetic dissipation with efficient particle acceleration and flares of high-energy radiation.« less

Using Computer-Based "Experiments" in the Analysis of Chemical Reaction Equilibria

ERIC Educational Resources Information Center

Li, Zhao; Corti, David S.

2018-01-01

The application of the Reaction Monte Carlo (RxMC) algorithm to standard textbook problems in chemical reaction equilibria is discussed. The RxMC method is a molecular simulation algorithm for studying the equilibrium properties of reactive systems, and therefore provides the opportunity to develop computer-based "experiments" for the…

Ideals versus reality: Are weight ideals associated with weight change in the population?

PubMed

Kärkkäinen, Ulla; Mustelin, Linda; Raevuori, Anu; Kaprio, Jaakko; Keski-Rahkonen, Anna

2016-04-01

To quantify weight ideals of young adults and to examine whether the discrepancy between actual and ideal weight is associated with 10-year body mass index (BMI) change in the population. This study comprised 4,964 adults from the prospective population-based FinnTwin16 study. They reported their actual and ideal body weight at age 24 (range 22-27) and 10 years later (attrition 24.6%). The correlates of discrepancy between actual and ideal body weight and the impact on subsequent BMI change were examined. The discrepancy between actual and ideal weight at 24 years was on average 3.9 kg (1.4 kg/m(2) ) among women and 1.2 kg (0.4 kg/m(2) ) among men. On average, participants gained weight during follow-up irrespective of baseline ideal weight: women ¯x = +4.8 kg (1.7 kg/m(2) , 95% CI 1.6-1.9 kg/m(2) ), men ¯x = +6.3 kg (2.0 kg/m(2) , 95% CI 1.8-2.1 kg/m(2) ). Weight ideals at 24 years were not correlated with 10-year weight change. At 34 years, just 13.2% of women and 18.9% of men were at or below the weight they had specified as their ideal weight at 24 years. Women and men adjusted their ideal weight upward over time. Irrespective of ideal weight at baseline, weight gain was nearly universal. Weight ideals were shifted upward over time. © 2016 The Obesity Society.

Complex blood flow patterns in an idealized left ventricle: A numerical study

NASA Astrophysics Data System (ADS)

Tagliabue, Anna; Dedè, Luca; Quarteroni, Alfio

2017-09-01

In this paper, we study the blood flow dynamics in a three-dimensional (3D) idealized left ventricle of the human heart whose deformation is driven by muscle contraction and relaxation in coordination with the action of the mitral and aortic valves. We propose a simplified but realistic mathematical treatment of the valves function based on mixed time-varying boundary conditions (BCs) for the Navier-Stokes equations modeling the flow. These switchings in time BCs, from natural to essential and vice versa, model either the open or the closed configurations of the valves. At the numerical level, these BCs are enforced by means of the extended Nitsche's method (Tagliabue et al., Int. J. Numer. Methods Fluids, 2017). Numerical results for the 3D idealized left ventricle obtained by means of Isogeometric Analysis are presented, discussed in terms of both instantaneous and phase-averaged quantities of interest and validated against those available in the literature, both experimental and computational. The complex blood flow patterns are analysed to describe the characteristic fluid properties, to show the transitional nature of the flow, and to highlight its main features inside the left ventricle. The sensitivity of the intraventricular flow patterns to the mitral valve properties is also investigated.

(Fuzzy) Ideals of BN-Algebras

PubMed Central

Walendziak, Andrzej

2015-01-01

The notions of an ideal and a fuzzy ideal in BN-algebras are introduced. The properties and characterizations of them are investigated. The concepts of normal ideals and normal congruences of a BN-algebra are also studied, the properties of them are displayed, and a one-to-one correspondence between them is presented. Conditions for a fuzzy set to be a fuzzy ideal are given. The relationships between ideals and fuzzy ideals of a BN-algebra are established. The homomorphic properties of fuzzy ideals of a BN-algebra are provided. Finally, characterizations of Noetherian BN-algebras and Artinian BN-algebras via fuzzy ideals are obtained. PMID:26125050

A Computer Algebra Approach to Solving Chemical Equilibria in General Chemistry

ERIC Educational Resources Information Center

Kalainoff, Melinda; Lachance, Russ; Riegner, Dawn; Biaglow, Andrew

2012-01-01

In this article, we report on a semester-long study of the incorporation into our general chemistry course, of advanced algebraic and computer algebra techniques for solving chemical equilibrium problems. The method presented here is an alternative to the commonly used concentration table method for describing chemical equilibria in general…

On the manifestation of coexisting nontrivial equilibria leading to potential well escapes in an inhomogeneous floating body

NASA Astrophysics Data System (ADS)

Sequeira, Dane; Wang, Xue-She; Mann, B. P.

2018-02-01

This paper examines the bifurcation and stability behavior of inhomogeneous floating bodies, specifically a rectangular prism with asymmetric mass distribution. A nonlinear model is developed to determine the stability of the upright and tilted equilibrium positions as a function of the vertical position of the center of mass within the prism. These equilibria positions are defined by an angle of rotation and a vertical position where rotational motion is restricted to a two dimensional plane. Numerical investigations are conducted using path-following continuation methods to determine equilibria solutions and evaluate stability. Bifurcation diagrams and basins of attraction that illustrate the stability of the equilibrium positions as a function of the vertical position of the center of mass within the prism are generated. These results reveal complex stability behavior with many coexisting solutions. Static experiments are conducted to validate equilibria orientations against numerical predictions with results showing good agreement. Dynamic experiments that examine potential well hopping behavior in a waveflume for various wave conditions are also conducted.

Modeling Complex Equilibria in ITC Experiments: Thermodynamic Parameters Estimation for a Three Binding Site Model

PubMed Central

Le, Vu H.; Buscaglia, Robert; Chaires, Jonathan B.; Lewis, Edwin A.

2013-01-01

Isothermal Titration Calorimetry, ITC, is a powerful technique that can be used to estimate a complete set of thermodynamic parameters (e.g. Keq (or ΔG), ΔH, ΔS, and n) for a ligand binding interaction described by a thermodynamic model. Thermodynamic models are constructed by combination of equilibrium constant, mass balance, and charge balance equations for the system under study. Commercial ITC instruments are supplied with software that includes a number of simple interaction models, for example one binding site, two binding sites, sequential sites, and n-independent binding sites. More complex models for example, three or more binding sites, one site with multiple binding mechanisms, linked equilibria, or equilibria involving macromolecular conformational selection through ligand binding need to be developed on a case by case basis by the ITC user. In this paper we provide an algorithm (and a link to our MATLAB program) for the non-linear regression analysis of a multiple binding site model with up to four overlapping binding equilibria. Error analysis demonstrates that fitting ITC data for multiple parameters (e.g. up to nine parameters in the three binding site model) yields thermodynamic parameters with acceptable accuracy. PMID:23262283

Supersonic beams at high particle densities: model description beyond the ideal gas approximation.

PubMed

Christen, Wolfgang; Rademann, Klaus; Even, Uzi

2010-10-28

Supersonic molecular beams constitute a very powerful technique in modern chemical physics. They offer several unique features such as a directed, collision-free flow of particles, very high luminosity, and an unsurpassed strong adiabatic cooling during the jet expansion. While it is generally recognized that their maximum flow velocity depends on the molecular weight and the temperature of the working fluid in the stagnation reservoir, not a lot is known on the effects of elevated particle densities. Frequently, the characteristics of supersonic beams are treated in diverse approximations of an ideal gas expansion. In these simplified model descriptions, the real gas character of fluid systems is ignored, although particle associations are responsible for fundamental processes such as the formation of clusters, both in the reservoir at increased densities and during the jet expansion. In this contribution, the various assumptions of ideal gas treatments of supersonic beams and their shortcomings are reviewed. It is shown in detail that a straightforward thermodynamic approach considering the initial and final enthalpy is capable of characterizing the terminal mean beam velocity, even at the liquid-vapor phase boundary and the critical point. Fluid properties are obtained using the most accurate equations of state available at present. This procedure provides the opportunity to naturally include the dramatic effects of nonideal gas behavior for a large variety of fluid systems. Besides the prediction of the terminal flow velocity, thermodynamic models of isentropic jet expansions permit an estimate of the upper limit of the beam temperature and the amount of condensation in the beam. These descriptions can even be extended to include spinodal decomposition processes, thus providing a generally applicable tool for investigating the two-phase region of high supersaturations not easily accessible otherwise.

Onset of fast "ideal" tearing in thin current sheets: Dependence on the equilibrium current profile

NASA Astrophysics Data System (ADS)

Pucci, F.; Velli, M.; Tenerani, A.; Del Sarto, D.

2018-03-01

In this paper, we study the scaling relations for the triggering of the fast, or "ideal," tearing instability starting from equilibrium configurations relevant to astrophysical as well as laboratory plasmas that differ from the simple Harris current sheet configuration. We present the linear tearing instability analysis for equilibrium magnetic fields which (a) go to zero at the boundary of the domain and (b) contain a double current sheet system (the latter previously studied as a Cartesian proxy for the m = 1 kink mode in cylindrical plasmas). More generally, we discuss the critical aspect ratio scalings at which the growth rates become independent of the Lundquist number S, in terms of the dependence of the Δ' parameter on the wavenumber k of unstable modes. The scaling Δ'(k) with k at small k is found to categorize different equilibria broadly: the critical aspect ratios may be even smaller than L/a ˜ Sα with α = 1/3 originally found for the Harris current sheet, but there exists a general lower bound α ≥ 1/4.

Social Interactions under Incomplete Information: Games, Equilibria, and Expectations

NASA Astrophysics Data System (ADS)

Yang, Chao

My dissertation research investigates interactions of agents' behaviors through social networks when some information is not shared publicly, focusing on solutions to a series of challenging problems in empirical research, including heterogeneous expectations and multiple equilibria. The first chapter, "Social Interactions under Incomplete Information with Heterogeneous Expectations", extends the current literature in social interactions by devising econometric models and estimation tools with private information in not only the idiosyncratic shocks but also some exogenous covariates. For example, when analyzing peer effects in class performances, it was previously assumed that all control variables, including individual IQ and SAT scores, are known to the whole class, which is unrealistic. This chapter allows such exogenous variables to be private information and models agents' behaviors as outcomes of a Bayesian Nash Equilibrium in an incomplete information game. The distribution of equilibrium outcomes can be described by the equilibrium conditional expectations, which is unique when the parameters are within a reasonable range according to the contraction mapping theorem in function spaces. The equilibrium conditional expectations are heterogeneous in both exogenous characteristics and the private information, which makes estimation in this model more demanding than in previous ones. This problem is solved in a computationally efficient way by combining the quadrature method and the nested fixed point maximum likelihood estimation. In Monte Carlo experiments, if some exogenous characteristics are private information and the model is estimated under the mis-specified hypothesis that they are known to the public, estimates will be biased. Applying this model to municipal public spending in North Carolina, significant negative correlations between contiguous municipalities are found, showing free-riding effects. The Second chapter "A Tobit Model with Social

Nonrelativistic fluids on scale covariant Newton-Cartan backgrounds

NASA Astrophysics Data System (ADS)

Mitra, Arpita

2017-12-01

The nonrelativistic covariant framework for fields is extended to investigate fields and fluids on scale covariant curved backgrounds. The scale covariant Newton-Cartan background is constructed using the localization of space-time symmetries of nonrelativistic fields in flat space. Following this, we provide a Weyl covariant formalism which can be used to study scale invariant fluids. By considering ideal fluids as an example, we describe its thermodynamic and hydrodynamic properties and explicitly demonstrate that it satisfies the local second law of thermodynamics. As a further application, we consider the low energy description of Hall fluids. Specifically, we find that the gauge fields for scale transformations lead to corrections of the Wen-Zee and Berry phase terms contained in the effective action.

Statistical mechanics of an ideal active fluid confined in a channel

NASA Astrophysics Data System (ADS)

Wagner, Caleb; Baskaran, Aparna; Hagan, Michael

The statistical mechanics of ideal active Brownian particles (ABPs) confined in a channel is studied by obtaining the exact solution of the steady-state Smoluchowski equation for the 1-particle distribution function. The solution is derived using results from the theory of two-way diffusion equations, combined with an iterative procedure that is justified by numerical results. Using this solution, we quantify the effects of confinement on the spatial and orientational order of the ensemble. Moreover, we rigorously show that both the bulk density and the fraction of particles on the channel walls obey simple scaling relations as a function of channel width. By considering a constant-flux steady state, an effective diffusivity for ABPs is derived which shows signatures of the persistent motion that characterizes ABP trajectories. Finally, we discuss how our techniques generalize to other active models, including systems whose activity is modeled in terms of an Ornstein-Uhlenbeck process.

Stalactite growth as a free-boundary problem: a geometric law and its platonic ideal.

PubMed

Short, Martin B; Baygents, James C; Beck, J Warren; Stone, David A; Toomey, Rickard S; Goldstein, Raymond E

2005-01-14

The chemical mechanisms underlying the growth of cave formations such as stalactites are well known, yet no theory has yet been proposed which successfully accounts for the dynamic evolution of their shapes. Here we consider the interplay of thin-film fluid dynamics, calcium carbonate chemistry, and CO2 transport in the cave to show that stalactites evolve according to a novel local geometric growth law which exhibits extreme amplification at the tip as a consequence of the locally-varying fluid layer thickness. Studies of this model show that a broad class of initial conditions is attracted to an ideal shape which is strikingly close to a statistical average of natural stalactites.

Characterizing the Nash equilibria of three-player Bayesian quantum games

NASA Astrophysics Data System (ADS)

Solmeyer, Neal; Balu, Radhakrishnan

2017-05-01

Quantum games with incomplete information can be studied within a Bayesian framework. We analyze games quantized within the EWL framework [Eisert, Wilkens, and Lewenstein, Phys Rev. Lett. 83, 3077 (1999)]. We solve for the Nash equilibria of a variety of two-player quantum games and compare the results to the solutions of the corresponding classical games. We then analyze Bayesian games where there is uncertainty about the player types in two-player conflicting interest games. The solutions to the Bayesian games are found to have a phase diagram-like structure where different equilibria exist in different parameter regions, depending both on the amount of uncertainty and the degree of entanglement. We find that in games where a Pareto-optimal solution is not a Nash equilibrium, it is possible for the quantized game to have an advantage over the classical version. In addition, we analyze the behavior of the solutions as the strategy choices approach an unrestricted operation. We find that some games have a continuum of solutions, bounded by the solutions of a simpler restricted game. A deeper understanding of Bayesian quantum game theory could lead to novel quantum applications in a multi-agent setting.

Potassium-argon (argon-argon), structural fabrics

USGS Publications Warehouse

Cosca, Michael A.; Rink, W. Jack; Thompson, Jereon

2014-01-01

Definition: 40Ar/39Ar geochronology of structural fabrics: The application of 40Ar/39Ar methods to date development of structural fabrics in geologic samples. Introduction: Structural fabrics develop during rock deformation at variable pressures (P), temperatures (T), fluid compositions (X), and time (t). Structural fabrics are represented in rocks by features such as foliations and shear zones developed at the mm to km scale. In ideal cases, the P-T-X history of a given structural fabric can be constrained using stable isotope, cation exchange, and/or mineral equilibria thermobarometry (Essene 1989). The timing of structural fabric development can be assessed qualitatively using geologic field observations or quantitatively using isotope-based geochronology. High-precision geochronology of the thermal and fluid flow histories associated with structural fabric development can answer fundamental geologic questions including (1) when hydrothermal fluids transported and deposited ore minerals, ...

Fluid Mechanics

NASA Astrophysics Data System (ADS)

Pnueli, David; Gutfinger, Chaim

1997-01-01

This text is intended for the study of fluid mechanics at an intermediate level. The presentation starts with basic concepts, in order to form a sound conceptual structure that can support engineering applications and encourage further learning. The presentation is exact, incorporating both the mathematics involved and the physics needed to understand the various phenomena in fluid mechanics. Where a didactical choice must be made between the two, the physics prevails. Throughout the book the authors have tried to reach a balance between exact presentation, intuitive grasp of new ideas, and creative applications of concepts. This approach is reflected in the examples presented in the text and in the exercises given at the end of each chapter. Subjects treated are hydrostatics, viscous flow, similitude and order of magnitude, creeping flow, potential flow, boundary layer flow, turbulent flow, compressible flow, and non-Newtonian flows. This book is ideal for advanced undergraduate students in mechanical, chemical, aerospace, and civil engineering. Solutions manual available.

High-resolution proton density weighted three-dimensional fast spin echo (3D-FSE) of the knee with IDEAL at 1.5 Tesla: comparison with 3D-FSE and 2D-FSE--initial experience.

PubMed

McMahon, Colm J; Madhuranthakam, Ananth J; Wu, Jim S; Yablon, Corrie M; Wei, Jesse L; Rofsky, Neil M; Hochman, Mary G

2012-02-01

To assess the feasibility of combining three-dimensional fast spin echo (3D-FSE) and Iterative-decomposition-of water-and-fat-with-echo asymmetry-and-least-squares-estimation (IDEAL) at 1.5 Tesla (T), generating a high-resolution 3D isotropic proton density-weighted image set with and without "fat-suppression" (FS) in a single acquisition, and to compare with 2D-FSE and 3D-FSE (without IDEAL). Ten asymptomatic volunteers prospectively underwent sagittal 3D-FSE-IDEAL, 3D-FSE, and 2D-FSE sequences at 1.5T (slice thickness [ST]: 0.8 mm, 0.8 mm, and 3.5 mm, respectively). 3D-FSE and 2D-FSE were repeated with frequency-selective FS. Fluid, cartilage, and muscle signal-to-noise ratio (SNR) and fluid-cartilage contrast-to-noise ratio (CNR) were compared among sequences. Three blinded reviewers independently scored quality of menisci/cartilage depiction for all sequences. "Fat-suppression" was qualitatively scored and compared among sequences. 3D-FSE-IDEAL fluid-cartilage CNR was higher than in 2D-FSE (P < 0.05), not different from 3D-FSE (P = 0.31). There was no significant difference in fluid SNR among sequences. 2D-FSE cartilage SNR was higher than in 3D FSE-IDEAL (P < 0.05), not different to 3D-FSE (P = 0.059). 2D-FSE muscle SNR was higher than in 3D-FSE-IDEAL (P < 0.05) and 3D-FSE (P < 0.05). Good or excellent depiction of menisci/cartilage was achieved using 3D-FSE-IDEAL in the acquired sagittal and reformatted planes. Excellent, homogeneous "fat-suppression" was achieved using 3D-FSE-IDEAL, superior to FS-3D-FSE and FS-2D-FSE (P < 0.05). 3D FSE-IDEAL is a feasible approach to acquire multiplanar images of diagnostic quality, both with and without homogeneous "fat-suppression" from a single acquisition. Copyright © 2011 Wiley Periodicals, Inc.

Implications for metal and volatile cycles from the pH of subduction zone fluids

NASA Astrophysics Data System (ADS)

Galvez, Matthieu E.; Connolly, James A. D.; Manning, Craig E.

2016-11-01

The chemistry of aqueous fluids controls the transport and exchange—the cycles—of metals and volatile elements on Earth. Subduction zones, where oceanic plates sink into the Earth’s interior, are the most important geodynamic setting for this fluid-mediated chemical exchange. Characterizing the ionic speciation and pH of fluids equilibrated with rocks at subduction zone conditions has long been a major challenge in Earth science. Here we report thermodynamic predictions of fluid-rock equilibria that tie together models of the thermal structure, mineralogy and fluid speciation of subduction zones. We find that the pH of fluids in subducted crustal lithologies is confined to a mildly alkaline range, modulated by rock volatile and chlorine contents. Cold subduction typical of the Phanerozoic eon favours the preservation of oxidized carbon in subducting slabs. In contrast, the pH of mantle wedge fluids is very sensitive to minor variations in rock composition. These variations may be caused by intramantle differentiation, or by infiltration of fluids enriched in alkali components extracted from the subducted crust. The sensitivity of pH to soluble elements in low abundance in the host rocks, such as carbon, alkali metals and halogens, illustrates a feedback between the chemistry of the Earth’s atmosphere-ocean system and the speciation of subduction zone fluids via the composition of the seawater-altered oceanic lithosphere. Our findings provide a perspective on the controlling reactions that have coupled metal and volatile cycles in subduction zones for more than 3 billion years7.

Multiple Reaction Equilibria--With Pencil and Paper: A Class Problem on Coal Methanation.

ERIC Educational Resources Information Center

Helfferich, Friedrich G.

1989-01-01

Points out a different and much simpler approach for the study of equilibria of multiple and heterogeneous chemical reactions. A simulation on coal methanation is used to teach the technique. An example and the methodology used are provided. (MVL)

Finite-beta equilibria for Wendelstein 7-X configurations using the Princeton Iterative Equilibrium Solver code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arndt, S.; Merkel, P.; Monticello, D.A.

Fixed- and free-boundary equilibria for Wendelstein 7-X (W7-X) [W. Lotz {ital et al.}, {ital Plasma Physics and Controlled Nuclear Fusion Research 1990} (Proc. 13th Int. Conf. Washington, DC, 1990), (International Atomic Energy Agency, Vienna, 1991), Vol. 2, p. 603] configurations are calculated using the Princeton Iterative Equilibrium Solver (PIES) [A. H. Reiman {ital et al.}, Comput. Phys. Commun., {bold 43}, 157 (1986)] to deal with magnetic islands and stochastic regions. Usually, these W7-X configurations require a large number of iterations for PIES convergence. Here, two methods have been successfully tested in an attempt to decrease the number of iterations neededmore » for convergence. First, periodic sequences of different blending parameters are used. Second, the initial guess is vastly improved by using results of the Variational Moments Equilibrium Code (VMEC) [S. P. Hirshmann {ital et al.}, Phys. Fluids {bold 26}, 3553 (1983)]. Use of these two methods have allowed verification of the Hamada condition and tendency of {open_quotes}self-healing{close_quotes} of islands has been observed. {copyright} {ital 1999 American Institute of Physics.}« less

Biot-Savart helicity versus physical helicity: A topological description of ideal flows

NASA Astrophysics Data System (ADS)

Sahihi, Taliya; Eshraghi, Homayoon

2014-08-01

For an isentropic (thus compressible) flow, fluid trajectories are considered as orbits of a family of one parameter, smooth, orientation-preserving, and nonsingular diffeomorphisms on a compact and smooth-boundary domain in the Euclidian 3-space which necessarily preserve a finite measure, later interpreted as the fluid mass. Under such diffeomorphisms the Biot-Savart helicity of the pushforward of a divergence-free and tangent to the boundary vector field is proved to be conserved and since these circumstances present an isentropic flow, the conservation of the "Biot-Savart helicity" is established for such flows. On the other hand, the well known helicity conservation in ideal flows which here we call it "physical helicity" is found to be an independent constant with respect to the Biot-Savart helicity. The difference between these two helicities reflects some topological features of the domain as well as the velocity and vorticity fields which is discussed and is shown for simply connected domains the two helicities coincide. The energy variation of the vorticity field is shown to be formally the same as for the incompressible flow obtained before. For fluid domains consisting of several disjoint solid tori, at each time, the harmonic knot subspace of smooth vector fields on the fluid domain is found to have two independent base sets with a special type of orthogonality between these two bases by which a topological description of the vortex and velocity fields depending on the helicity difference is achieved since this difference is shown to depend only on the harmonic knot parts of velocity, vorticity, and its Biot-Savart vector field. For an ideal magnetohydrodynamics (MHD) flow three independent constant helicities are reviewed while the helicity of magnetic potential is generalized for non-simply connected domains by inserting a special harmonic knot field in the dynamics of the magnetic potential. It is proved that the harmonic knot part of the vorticity

Medium-β free-boundary equilibria of a quasi-isodynamic stellarator

NASA Astrophysics Data System (ADS)

Mikhailov, M. I.; Drevlak, M.; Nührenberg, J.; Shafranov, V. D.

2012-06-01

Free-boundary MHD equilibria with magnetic surfaces in the vacuum region surrounding the plasma [E. Strumberger, Nucl. Fusion 37, 19 (1997); M. Drevlak, D. Monticello, and A. Reiman, Nucl. Fusion 45, 731 (2005)] are obtained for a quasi-isodynamic stellarator [A. A. Subbotin, M. I. Mikhailov, V. D. Shafranov et al., Nucl. Fusion 46, 921 (2006); M. I. Mikhailov, J. Nuhrenberg, and V. D. Shafranov, Plasma Phys. Rep. 35, 529 (2009)].

Medium-{beta} free-boundary equilibria of a quasi-isodynamic stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mikhailov, M. I.; Drevlak, M.; Nuehrenberg, J.

Free-boundary MHD equilibria with magnetic surfaces in the vacuum region surrounding the plasma [E. Strumberger, Nucl. Fusion 37, 19 (1997); M. Drevlak, D. Monticello, and A. Reiman, Nucl. Fusion 45, 731 (2005)] are obtained for a quasi-isodynamic stellarator [A. A. Subbotin, M. I. Mikhailov, V. D. Shafranov et al., Nucl. Fusion 46, 921 (2006); M. I. Mikhailov, J. Nuhrenberg, and V. D. Shafranov, Plasma Phys. Rep. 35, 529 (2009)].

Characteristics and carbon stable isotopes of fluids in the Southern Kerala granulites and their bearing on the source of CO2

NASA Technical Reports Server (NTRS)

Santosh, M.; Jackson, D. H.; Mattey, D. P.; Harris, N. B. W.

1988-01-01

Carbon dioxide-rich inclusions commonly occur in the banded charnockites and khondalites of southern Kerala as well as in the incipient charnockites formed by desiccation of gneisses along oriented zones. The combined high density fluid inclusion isochores and the range of thermometric estimates from mineral assemblages indicate entrapment pressures in the range of 5.4 to 6.1 Kbar. The CO2 equation of state barometry closely compares with the 5 plus or minus 1 Kbar estimate from mineral phases for the region. The isochores for the high density fluid inclusions in all the three rock types pass through the P-T domain recorded by phase equilibria, implying that carbon dioxide was the dominating ambient fluid species during peak metamorphic conditions. In order to constrain the source of fluids and to evaluate the mechanism of desiccation, researchers undertook detailed investigations of the carbon stable isotope composition of entrapped fluids. Researchers report here the results of preliminary studies in some of the classic localities in southern Kerala namely, Ponmudi, Kottavattom, Manali and Kadakamon.

Phase equilibria of H2SO4, HNO3, and HCl hydrates and the composition of polar stratospheric clouds

NASA Technical Reports Server (NTRS)

Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

1995-01-01

Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

Phase Equilibria of H2SO4, HNO3, and HCl Hydrates and the Composition of Polar Stratospheric Clouds

NASA Technical Reports Server (NTRS)

Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

1995-01-01

Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

Ideal magnetohydrodynamic theory for localized interchange modes in toroidal anisotropic plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Tonghui, E-mail: thshi@ipp.ac.cn; Wan, B. N.; Sun, Y.

2016-08-15

Ideal magnetohydrodynamic theory for localized interchange modes is developed for toroidal plasmas with anisotropic pressure. The work extends the existing theories of Johnson and Hastie [Phys. Fluids 31, 1609 (1988)], etc., to the low n mode case, where n is the toroidal mode number. Also, the plasma compressibility is included, so that the coupling of the parallel motion to perpendicular one, i.e., the so-called apparent mass effect, is investigated in the anisotropic pressure case. The singular layer equation is obtained, and the generalized Mercier's criterion is derived.

The Place of Ideals in Teaching.

ERIC Educational Resources Information Center

Hansen, David T.

This paper examines whether ideals and idealism have a role to play in teaching, identifying some ambiguities and problems associated with ideals and arguing that ideals figure importantly in teaching, but they are ideals of character or personhood as much as they are ideals of educational purpose. The first section focuses on the promise and…

Non-axisymmetric ideal equilibrium and stability of ITER plasmas with rotating RMPs

NASA Astrophysics Data System (ADS)

Ham, C. J.; Cramp, R. G. J.; Gibson, S.; Lazerson, S. A.; Chapman, I. T.; Kirk, A.

2016-08-01

The magnetic perturbations produced by the resonant magnetic perturbation (RMP) coils will be rotated in ITER so that the spiral patterns due to strike point splitting which are locked to the RMP also rotate. This is to ensure even power deposition on the divertor plates. VMEC equilibria are calculated for different phases of the RMP rotation. It is demonstrated that the off harmonics rotate in the opposite direction to the main harmonic. This is an important topic for future research to control and optimize ITER appropriately. High confinement mode (H-mode) is favourable for the economics of a potential fusion power plant and its use is planned in ITER. However, the high pressure gradient at the edge of the plasma can trigger periodic eruptions called edge localized modes (ELMs). ELMs have the potential to shorten the life of the divertor in ITER (Loarte et al 2003 Plasma Phys. Control. Fusion 45 1549) and so methods for mitigating or suppressing ELMs in ITER will be important. Non-axisymmetric RMP coils will be installed in ITER for ELM control. Sampling theory is used to show that there will be significant a {{n}\\text{coils}}-{{n}\\text{rmp}} harmonic sideband. There are nine coils toroidally in ITER so {{n}\\text{coils}}=9 . This results in a significant n  =  6 component to the {{n}\\text{rmp}}=3 applied field and a significant n  =  5 component to the {{n}\\text{rmp}}=4 applied field. Although the vacuum field has similar amplitudes of these harmonics the plasma response to the various harmonics dictates the final equilibrium. Magnetic perturbations with toroidal mode number n  =  3 and n  =  4 are applied to a 15 MA, {{q}95}≈ 3 burning ITER plasma. We use a three-dimensional ideal magnetohydrodynamic model (VMEC) to calculate ITER equilibria with applied RMPs and to determine growth rates of infinite n ballooning modes (COBRA). The {{n}\\text{rmp}}=4 case shows little change in ballooning mode growth rate as the RMP is

Theoretical study on the vibrational spectra of methoxy- and formyl-dihydroxy- trans-stilbenes and their hydrolytic equilibria

NASA Astrophysics Data System (ADS)

Molnár, Viktor; Billes, Ferenc; Tyihák, Ernő; Mikosch, Hans

2008-02-01

Compounds formed by exchanging one of the resveratrol hydroxy groups to methoxy or formyl groups are biologically important. Quantum chemical DFT calculations were applied for the simulation of some of their properties. Their optimized structures and charge distributions were computed. Based on the calculated vibrational force constants and optimized molecular structure infrared and Raman spectra were calculated. The characteristics of the vibrational modes were determined by normal coordinate analysis. Applying the calculated thermodynamic functions also for resveratrol, methanol, formaldehyde and water, thermodynamic equilibria were calculated for the equilibria between resveratrol and its methyl and formyl substituted derivatives, respectively.

Structural characterization/correlation of calorimetric properties of coal fluids: Final report, September 1, 1985--August 31, 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starling, K.E.; Mallinson, R.G.; Li, M.H.

The objective of this research is to examine the relationship between the calorimetric properties of coal fluids and their molecular functional group composition. Coal fluid samples which have had their calorimetric properties measured are characterized using proton NMR, IR, and elemental analysis. These characterizations are then used in a chemical structural model to determine the composition of the coal fluid in terms of the important molecular functional groups. These functional groups are particularly important in determining the intramolecular based properties of a fluid, such as ideal gas heat capacities. Correlational frameworks for ideal gas heat capacities are then examined withinmore » an existing equation of state methodology to determine an optimal correlation. The optimal correlation for obtaining the characterization/chemical structure information and the sensitivity of the correlation to the characterization and structural model is examined. 8 refs.« less

Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, T. F.; Lawrence Livermore National Laboratory, Livermore, California 94550; Xu, X. Q.

2016-03-15

A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan basedmore » on “Cyclone base case parameter set.” We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.« less

Metal biosorption equilibria in a ternary system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chong, K.H.; Volesky, B.

Equilibrium metal uptake performance of a biosorbent prepared from Ascophyllum nodosum seaweed biomass was studied using aqueous solutions containing copper, cadmium, and zinc ions in binary and ternary mixtures. Triangular equilibrium diagrams can graphically represent all the ternary equilibrium sorption data. Application of the multicomponent Langmuir model to describe the three-metal system revealed its nonideal characteristics, whereby the value of apparent dissociation constants for the respective metals differed for each system. This restricted the prediction of the ternary equilibria from the binary systems. However, some predictions of the ternary system behavior from the model were consistent with experimental data andmore » with conclusions postulated from the three possible binary subsystems.« less

Determination of gas volume trapped in a closed fluid system

NASA Technical Reports Server (NTRS)

Hunter, W. F.; Jolley, J. E.

1971-01-01

Technique involves extracting known volume of fluid and measuring system before and after extraction, volume of entrapped gas is then computed. Formula derived from ideal gas laws is basis of this method. Technique is applicable to thermodynamic cycles and hydraulic systems.

Medical ethics and more: ideal theories, non-ideal theories and conscientious objection.

PubMed

Luna, Florencia

2015-01-01

Doing 'good medical ethics' requires acknowledgment that it is often practised in non-ideal circumstances! In this article I present the distinction between ideal theory (IT) and non-ideal theory (NIT). I show how IT may not be the best solution to tackle problems in non-ideal contexts. I sketch a NIT framework as a useful tool for bioethics and medical ethics and explain how NITs can contribute to policy design in non-ideal circumstances. Different NITs can coexist and be evaluated vis-à-vis the IT. Additionally, I address what an individual doctor ought to do in this non-ideal context with the view that knowledge of NITs can facilitate the decision-making process. NITs help conceptualise problems faced in the context of non-compliance and scarcity in a better and more realistic way. Deciding which policy is optimal in such contexts may influence physicians' decisions regarding their patients. Thus, this analysis-usually identified only with policy making-may also be relevant to medical ethics. Finally, I recognise that this is merely a first step in an unexplored but fundamental theoretical area and that more work needs to be done. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Large Uncertainty in Estimating pCO2 From Carbonate Equilibria in Lakes

NASA Astrophysics Data System (ADS)

Golub, Malgorzata; Desai, Ankur R.; McKinley, Galen A.; Remucal, Christina K.; Stanley, Emily H.

2017-11-01

Most estimates of carbon dioxide (CO2) evasion from freshwaters rely on calculating partial pressure of aquatic CO2 (pCO2) from two out of three CO2-related parameters using carbonate equilibria. However, the pCO2 uncertainty has not been systematically evaluated across multiple lake types and equilibria. We quantified random errors in pH, dissolved inorganic carbon, alkalinity, and temperature from the North Temperate Lakes Long-Term Ecological Research site in four lake groups across a broad gradient of chemical composition. These errors were propagated onto pCO2 calculated from three carbonate equilibria, and for overlapping observations, compared against uncertainties in directly measured pCO2. The empirical random errors in CO2-related parameters were mostly below 2% of their median values. Resulting random pCO2 errors ranged from ±3.7% to ±31.5% of the median depending on alkalinity group and choice of input parameter pairs. Temperature uncertainty had a negligible effect on pCO2. When compared with direct pCO2 measurements, all parameter combinations produced biased pCO2 estimates with less than one third of total uncertainty explained by random pCO2 errors, indicating that systematic uncertainty dominates over random error. Multidecadal trend of pCO2 was difficult to reconstruct from uncertain historical observations of CO2-related parameters. Given poor precision and accuracy of pCO2 estimates derived from virtually any combination of two CO2-related parameters, we recommend direct pCO2 measurements where possible. To achieve consistently robust estimates of CO2 emissions from freshwater components of terrestrial carbon balances, future efforts should focus on improving accuracy and precision of CO2-related parameters (including direct pCO2) measurements and associated pCO2 calculations.

Phase equilibria in fullerene-containing systems as a basis for development of manufacture and application processes for nanocarbon materials

NASA Astrophysics Data System (ADS)

Semenov, K. N.; Charykov, N. A.; Postnov, V. N.; Sharoyko, V. V.; Murin, I. V.

2016-01-01

This review is the first attempt to integrate the available data on all types of phase equilibria (solubility, extraction and sorption) in systems containing light fullerenes (C60 and C70). In the case of solubility diagrams, the following types of phase equilibria are considered: individual fullerene (C60 or C70)-solvent under polythermal and polybaric conditions; C60-C70-solvent, individual fullerene-solvent(1)-solvent(2), as well as multicomponent systems comprising a single fullerene or an industrial mixture of fullerenes and vegetable oils, animal fats or essential oils under polythermal conditions. All published experimental data on the extraction equilibria in C60-C70-liquid phase(1)-liquid phase(2) systems are described systematically and the sorption characteristics of various materials towards light fullerenes are estimated. The possibility of application of these experimental data for development of pre-chromatographic and chromatographic methods for separation of fullerene mixtures and application of fullerenes as nanomodifiers are described. The bibliography includes 87 references.

Blood Flow in Idealized Vascular Access for Hemodialysis: A Review of Computational Studies.

PubMed

Ene-Iordache, Bogdan; Remuzzi, Andrea

2017-09-01

Although our understanding of the failure mechanism of vascular access for hemodialysis has increased substantially, this knowledge has not translated into successful therapies. Despite advances in technology, it is recognized that vascular access is difficult to maintain, due to complications such as intimal hyperplasia. Computational studies have been used to estimate hemodynamic changes induced by vascular access creation. Due to the heterogeneity of patient-specific geometries, and difficulties with obtaining reliable models of access vessels, idealized models were often employed. In this review we analyze the knowledge gained with the use of computational such simplified models. A review of the literature was conducted, considering studies employing a computational fluid dynamics approach to gain insights into the flow field phenotype that develops in idealized models of vascular access. Several important discoveries have originated from idealized model studies, including the detrimental role of disturbed flow and turbulent flow, and the beneficial role of spiral flow in intimal hyperplasia. The general flow phenotype was consistent among studies, but findings were not treated homogeneously since they paralleled achievements in cardiovascular biomechanics which spanned over the last two decades. Computational studies in idealized models are important for studying local blood flow features and evaluating new concepts that may improve the patency of vascular access for hemodialysis. For future studies we strongly recommend numerical modelling targeted at accurately characterizing turbulent flows and multidirectional wall shear disturbances.

Metal Complexation in Xylem Fluid 1

PubMed Central

White, Michael C.; Decker, A. Morris; Chaney, Rufus L.

1981-01-01

Xylem fluid was analyzed for numerous solutes to characterize chemically the sap as a medium for forming and transporting metal complexes. The stem exudate was collected hourly for 8 hours from topped 31-day-old soybean (Glycine max L. Merr.) and 46-day-old tomato (Lycopersicon esculentum Mill.) plants grown in normal (0.5 micromolar) and Za-phytotoxic nutrient solutions. Soybean plants were grown in the normal and high-Zn solutions for 24 days; tomato plants were grown for 32 days. The exudate was analyzed for seven organic acids, 22 amino acids, eight inorganic solutes, apparent ionic strength, and pH. Significant changes in many solutes occurred over the 8-hour sampling period. These fluctuations depended on plant species, individual solute, and Zn treatment, and demonstrated that extrapolation of xylem-fluid analyses to whole-plant xylem sap is valid only for sap samples collected shortly after topping a plant. Exudate pH decreased over the 8-hour period for both species; exudate ionic strength increased for tomato and decreased for soybean. At the normal-Zn treatment (0 to 1 hour), the highest acid micromolar concentrations in soybean exudate were: asparagine, 2,583; citric, 1,706; malic, 890; and malonic, 264. Under the same conditions, the highest acid micromolar concentrations in tomato exudate were: maleic, 1,206; malic, 628; glutamine, 522; citric, 301; and asparagine, 242. Cysteine and methionine were above detection limits only in soybean exudate. Zinc phytotoxicity caused significant changes in many solutes. The analyses reported here provide a comprehensive data base for further studies on metal-complex equilibria in xylem fluid. PMID:16661664

Developmental Idealism in China

PubMed Central

Thornton, Arland; Xie, Yu

2016-01-01

This paper examines the intersection of developmental idealism with China. It discusses how developmental idealism has been widely disseminated within China and has had enormous effects on public policy and programs, on social institutions, and on the lives of individuals and their families. This dissemination of developmental idealism to China began in the 19th century, when China met with several military defeats that led many in the country to question the place of China in the world. By the beginning of the 20th century, substantial numbers of Chinese had reacted to the country’s defeats by exploring developmental idealism as a route to independence, international respect, and prosperity. Then, with important but brief aberrations, the country began to implement many of the elements of developmental idealism, a movement that became especially important following the assumption of power by the Communist Party of China in 1949. This movement has played a substantial role in politics, in the economy, and in family life. The beliefs and values of developmental idealism have also been directly disseminated to the grassroots in China, where substantial majorities of Chinese citizens have assimilated them. These ideas are both known and endorsed by very large numbers in China today. PMID:28316833

Developmental Idealism in China.

PubMed

Thornton, Arland; Xie, Yu

2016-10-01

This paper examines the intersection of developmental idealism with China. It discusses how developmental idealism has been widely disseminated within China and has had enormous effects on public policy and programs, on social institutions, and on the lives of individuals and their families. This dissemination of developmental idealism to China began in the 19 th century, when China met with several military defeats that led many in the country to question the place of China in the world. By the beginning of the 20 th century, substantial numbers of Chinese had reacted to the country's defeats by exploring developmental idealism as a route to independence, international respect, and prosperity. Then, with important but brief aberrations, the country began to implement many of the elements of developmental idealism, a movement that became especially important following the assumption of power by the Communist Party of China in 1949. This movement has played a substantial role in politics, in the economy, and in family life. The beliefs and values of developmental idealism have also been directly disseminated to the grassroots in China, where substantial majorities of Chinese citizens have assimilated them. These ideas are both known and endorsed by very large numbers in China today.

Simulating Dynamic Equilibria: A Class Experiment

NASA Astrophysics Data System (ADS)

Harrison, John A.; Buckley, Paul D.

2000-08-01

A first-order reversible reaction is simulated on an overhead projector using small coins or discs. A simulation is carried out in which initially there are 24 discs representing reactant A and none representing reactant B. At the end of each minute half of the reactant A discs get converted to reactant B, and one quarter of the reactant B discs get converted to reactant A discs. Equilibrium is established with 8 A discs and 16 B discs, and no further net change is observed as the simulation continues. Another simulation beginning with 48 A discs and 0 B discs leads at equilibrium to 16 A discs and 32 B discs. These results illustrate how dynamic equilibria are established and allow the introduction of the concept of an equilibrium constant. Le Châtelier's principle is illustrated by further simulations.

Structural characterization/correlation of calorimetric properties of coal fluids: Second annual report, September 1, 1986-August 31, 1987

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starling, K.E.; Mallinson, R.G.; Li, M.H.

The objective of this research is to examine the relationship between the calorimetric properties of coal fluids and their molecular functional group composition. Coal fluid samples which have had their calorimetric properties measured are characterized using proton NMR, ir, and elemental analysis. These characterizations are then used in a chemical structural model to determine the composition of the coal fluid in terms of the important molecular functional groups. These functional groups are particularly important in determining the intramolecular based properties of a fluid, such as ideal gas heat capacities. Correlational frameworks for ideal gas heat capacities are then examined withinmore » an existing equation of state methodology to determine an optimal correlation. The optimal correlation for obtaining the characterization/chemical structure information and the sensitivity of the correlation to the characterization and structural model is examined.« less

Guidelines for European workplace drug testing in oral fluid.

PubMed

Cooper, Gail; Moore, Christine; George, Claire; Pichini, Simona

2011-05-01

Over the past decade, oral fluid has established itself as a robust testing matrix for monitoring drug use or misuse. Commercially available collection devices provide opportunities to collect and test oral fluid by the roadside and near-patient testing with both clinical and criminal justice applications. One of the main advantages of oral fluid relates to the collection of the matrix which is non-invasive, simple, and can be carried out under direct observation making it ideal for workplace drug testing. Laboratories offering legally defensible oral fluid workplace drug testing must adhere to national and international quality standards (ISO/IEC 17025); however, these standards do not address issues specific to oral fluid testing. The European Workplace Drug Testing Society (EWDTS) recognizes the importance of providing best practice guidelines to organizations offering testing and those choosing to use oral fluid drug testing to test their employees. The aim of this paper is to present the EWDTS guidelines for oral fluid workplace drug testing. Copyright © 2011 John Wiley & Sons, Ltd.

On subgame perfect equilibria in quantum Stackelberg duopoly

NASA Astrophysics Data System (ADS)

Frąckiewicz, Piotr; Pykacz, Jarosław

2018-02-01

Our purpose is to study the Stackelberg duopoly with the use of the Li-Du-Massar quantum duopoly scheme. The result of Lo and Kiang has shown that the correlation of players's quantities caused by the quantum entanglement enlarges the first-mover advantage in the quantum Stackelberg duopoly. However, the interval of entanglement parameters for which this result is valid is bounded from above. It has been an open question what the equilibrium result is over the upper bound, in particular when the entanglement parameter goes to infinity. Our work provides complete analysis of subgame perfect equilibria of the game for all the values of the entanglement parameter.

The Stability and Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation

DTIC Science & Technology

2005-01-01

imaging, drug delivery, and hyperthermia treatment for cancer . Ideal magnetic nanoparticle fluids have well-separated, biocompatible nanoparticles with a...Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation DISTRIBUTION: Approved for public release, distribution unlimited This paper...Oxidation Resistance of Iron- and Cobalt-Based Magnetic Nanoparticle Fluids Fabricated by Inert-Gas Condensation Nguyen H. Hail, Raymond Lemoine’, Shaina

GPU.proton.DOCK: Genuine Protein Ultrafast proton equilibria consistent DOCKing.

PubMed

Kantardjiev, Alexander A

2011-07-01

GPU.proton.DOCK (Genuine Protein Ultrafast proton equilibria consistent DOCKing) is a state of the art service for in silico prediction of protein-protein interactions via rigorous and ultrafast docking code. It is unique in providing stringent account of electrostatic interactions self-consistency and proton equilibria mutual effects of docking partners. GPU.proton.DOCK is the first server offering such a crucial supplement to protein docking algorithms--a step toward more reliable and high accuracy docking results. The code (especially the Fast Fourier Transform bottleneck and electrostatic fields computation) is parallelized to run on a GPU supercomputer. The high performance will be of use for large-scale structural bioinformatics and systems biology projects, thus bridging physics of the interactions with analysis of molecular networks. We propose workflows for exploring in silico charge mutagenesis effects. Special emphasis is given to the interface-intuitive and user-friendly. The input is comprised of the atomic coordinate files in PDB format. The advanced user is provided with a special input section for addition of non-polypeptide charges, extra ionogenic groups with intrinsic pK(a) values or fixed ions. The output is comprised of docked complexes in PDB format as well as interactive visualization in a molecular viewer. GPU.proton.DOCK server can be accessed at http://gpudock.orgchm.bas.bg/.

Vapor-Liquid Equilibria Using the Gibbs Energy and the Common Tangent Plane Criterion

ERIC Educational Resources Information Center

Olaya, Maria del Mar; Reyes-Labarta, Juan A.; Serrano, Maria Dolores; Marcilla, Antonio

2010-01-01

Phase thermodynamics is often perceived as a difficult subject with which many students never become fully comfortable. The Gibbsian geometrical framework can help students to gain a better understanding of phase equilibria. An exercise to interpret the vapor-liquid equilibrium of a binary azeotropic mixture, using the equilibrium condition based…

Analysis of Variability in Intraoperative Fluid Administration for Colorectal Surgery: An Argument for Goal-Directed Fluid Therapy.

PubMed

Quinn, Timothy D; Brovman, Ethan Y; Urman, Richard D

2017-09-01

Fluid therapy in the perioperative period varies greatly between anesthesia providers and may have a negative impact on surgical outcomes. We conducted a retrospective analysis of 705 elective colorectal cases consisting of colectomies, ileocolic resections, and low anterior resections at an academic institution from January 1, 2010 to May 29, 2015, collected by our electronic medical record before implementation of Enhanced Recovery After Surgery (ERAS ® ) pathways. The mean for total crystalloid administration was 2578 mL with a standard deviation (SD) that was approximately 50% of the mean value. A combination of both normal saline and lactated Ringer's solution was used in almost all cases without a clear rationale for fluid choice. Fluid administered to patients was disproportional to measured intraoperative fluid losses (estimated blood loss and urine output) by a factor of 10. The average rate of fluid given was 1050 mL/h with an SD of nearly the same amount (951 mL). There was a variability of over 67% in total crystalloid administered based on both ideal body weight and total body weight. We found that a wide variability in the amount and type of fluid therapy administered existed at our institution before implementation of a colorectal ERAS pathway or routine use of goal-directed fluid therapy (GDFT). ERAS pathways with GDFT protocols could lead to more rational and consistent fluid therapy leading to improved outcomes.

Propagation of exponential shock wave in an axisymmetric rotating non-ideal dusty gas

NASA Astrophysics Data System (ADS)

Nath, G.

2016-09-01

One-dimensional unsteady isothermal and adiabatic flow behind a strong exponential shock wave propagating in a rotational axisymmetric mixture of non-ideal gas and small solid particles, which has variable azimuthal and axial fluid velocities, is analyzed. The shock wave is driven out by a piston moving with time according to exponential law. The azimuthal and axial components of the fluid velocity in the ambient medium are assumed to be varying and obeying exponential laws. In the present work, small solid particles are considered as pseudo-fluid with the assumption that the equilibrium flow-conditions are maintained in the flow-field, and the viscous-stress and heat conduction of the mixture are negligible. Solutions are obtained in both the cases, when the flow between the shock and the piston is isothermal or adiabatic by taking into account the components of vorticity vector and compressibility. It is found that the assumption of zero temperature gradient brings a profound change in the density, axial component of vorticity vector and compressibility distributions as compared to that of the adiabatic case. To investigate the behavior of the flow variables and the influence on the shock wave propagation by the parameter of non-idealness of the gas overline{b} in the mixture as well as by the mass concentration of solid particles in the mixture Kp and by the ratio of the density of solid particles to the initial density of the gas G1 are worked out in detail. It is interesting to note that the shock strength increases with an increase in G1 ; whereas it decreases with an increase in overline{b} . Also, a comparison between the solutions in the cases of isothermal and adiabatic flows is made.

Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

NASA Astrophysics Data System (ADS)

Faghihi, M.; Scheffel, J.

1987-12-01

The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m ≥ 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for P > P and large β

Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems

NASA Astrophysics Data System (ADS)

Zolotov, Mikhail Yu.

2012-08-01

Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350 °C), and pressures (<2 kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na+, Cl-, CO32-,HCO3-, K+, OH-, H2, and CO2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH- anions coexist with secondary mineralogy depleted in Na. The Na2CO3 and NaHCO3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H2 gas. Hydrogen, CO2, and H2O dominate in the gaseous phase, though the abundance

Strategic trade between two regions with partial local consumer protection - General setup and nash equilibria

NASA Astrophysics Data System (ADS)

Iordanov, Iordan V.; Vassilev, Andrey A.

2017-12-01

We construct a model of the trade relations between two regions for the case when the trading entities (consumers) compete for a scarce good and there is an element of strategic interdependence in the trading process. Additionally, local consumers enjoy partial protection in the form of guaranteed access to a part of the locally-supplied quantity of the good. The model is formulated for the general asymmetric case, where the two regions differ in terms of parameters such as income, size of the local market supply, degree of protection and transportation costs. For this general model we establish the existence of Nash equilibria and obtain their form as a function of the model parameters, producing a typology of the equilibria. This is a required step in order to rigorously study various types of price dynamics for the model.

Thermodynamic calculations in the system CH4-H2O and methane hydrate phase equilibria

USGS Publications Warehouse

Circone, S.; Kirby, S.H.; Stern, L.A.

2006-01-01

Using the Gibbs function of reaction, equilibrium pressure, temperature conditions for the formation of methane clathrate hydrate have been calculated from the thermodynamic properties of phases in the system CH4-H 2O. The thermodynamic model accurately reproduces the published phase-equilibria data to within ??2 K of the observed equilibrium boundaries in the range 0.08-117 MPa and 190-307 K. The model also provides an estimate of the third-law entropy of methane hydrate at 273.15 K, 0.1 MPa of 56.2 J mol-1 K-1 for 1/n CH4??H 2O, where n is the hydrate number. Agreement between the calculated and published phase-equilibria data is optimized when the hydrate composition is fixed and independent of the pressure and temperature for the conditions modeled. ?? 2006 American Chemical Society.

Modelling and stability analysis of switching impulsive power systems with multiple equilibria

NASA Astrophysics Data System (ADS)

Zhu, Liying; Qiu, Jianbin; Chadli, Mohammed

2017-12-01

This paper tries to model power systems accompanied with a series of faults in the form of switched impulsive Hamiltonian systems (SIHSs) with multiple equilibria (ME) and unstable subsystems (US), and then analyze long-term stability issues of the power systems from the viewpoint of mathematics. According to the complex phenomena of switching actions of stages and generators, impulses of state, and existence of multiple equilibria, this paper first introduces an SIHS with ME and US to formulate a switching impulsive power system composed of an active generator, a standby generator, and an infinite load. Then, based on special system structures, a unique compact region containing all ME is determined, and novel stability concepts of region stability (RS), asymptotic region stability (ARS), and exponential region stability (ERS) are defined for such SIHS with respect to the region. Third, based on the introduced stability concepts, this paper proposes a necessary and sufficient condition of RS and ARS and a sufficient condition of ERS for the power system with respect to the region via the maximum energy function method. Finally, numerical simulations are carried out for a power system to show the effectiveness and practicality of the obained novel results.

Consistency argued students of fluid

NASA Astrophysics Data System (ADS)

Viyanti; Cari; Suparmi; Winarti; Slamet Budiarti, Indah; Handika, Jeffry; Widyastuti, Fatma

2017-01-01

Problem solving for physics concepts through consistency arguments can improve thinking skills of students and it is an important thing in science. The study aims to assess the consistency of the material Fluid student argmentation. The population of this study are College students PGRI Madiun, UIN Sunan Kalijaga Yogyakarta and Lampung University. Samples using cluster random sampling, 145 samples obtained by the number of students. The study used a descriptive survey method. Data obtained through multiple-choice test and interview reasoned. Problem fluid modified from [9] and [1]. The results of the study gained an average consistency argmentation for the right consistency, consistency is wrong, and inconsistent respectively 4.85%; 29.93%; and 65.23%. Data from the study have an impact on the lack of understanding of the fluid material which is ideally in full consistency argued affect the expansion of understanding of the concept. The results of the study as a reference in making improvements in future studies is to obtain a positive change in the consistency of argumentations.

Shear waves in inhomogeneous, compressible fluids in a gravity field.

PubMed

Godin, Oleg A

2014-03-01

While elastic solids support compressional and shear waves, waves in ideal compressible fluids are usually thought of as compressional waves. Here, a class of acoustic-gravity waves is studied in which the dilatation is identically zero, and the pressure and density remain constant in each fluid particle. These shear waves are described by an exact analytic solution of linearized hydrodynamics equations in inhomogeneous, quiescent, inviscid, compressible fluids with piecewise continuous parameters in a uniform gravity field. It is demonstrated that the shear acoustic-gravity waves also can be supported by moving fluids as well as quiescent, viscous fluids with and without thermal conductivity. Excitation of a shear-wave normal mode by a point source and the normal mode distortion in realistic environmental models are considered. The shear acoustic-gravity waves are likely to play a significant role in coupling wave processes in the ocean and atmosphere.

Conversion of the dominantly ideal perturbations into a tearing mode after a sawtooth crash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Igochine, V., E-mail: valentin.igochine@ipp.mpg.de; Gude, A.; Günter, S.

2014-11-15

Forced magnetic reconnection is a topic of common interest in astrophysics, space science, and magnetic fusion research. The tearing mode formation process after sawtooth crashes implies the existence of this type of magnetic reconnection and is investigated in great detail in the ASDEX Upgrade tokamak. The sawtooth crash provides a fast relaxation of the core plasma temperature and can trigger a tearing mode at a neighbouring resonant surface. It is demonstrated for the first time that the sawtooth crash leads to a dominantly ideal kink mode formation at the resonant surface immediately after the sawtooth crash. Local measurements show thatmore » this kink mode transforms into a tearing mode on a much longer timescale (10{sup −3}s−10{sup −2}s) than the sawtooth crash itself (10{sup −4}s). The ideal kink mode formed after the sawtooth crash provides the driving force for magnetic reconnection and its amplitude is one of the critical parameters for the length of the transition phase from a ideal into an resistive mode. Nonlinear two fluid MHD simulations confirm these observations.« less

Scaling in two-fluid pinch-off

NASA Astrophysics Data System (ADS)

Pommer, Chris; Harris, Michael; Basaran, Osman

2010-11-01

The physics of two-fluid pinch-off, which arises whenever drops, bubbles, or jets of one fluid are ejected from a nozzle into another fluid, is scientifically important and technologically relevant. While the breakup of a drop in a passive environment is well understood, the physics of pinch-off when both the inner and outer fluids are dynamically active remains inadequately understood. Here, the breakup of a compound jet whose core and shell are incompressible Newtonian fluids is analyzed computationally when the interior is a "bubble" and the exterior is a liquid. The numerical method employed is an implicit method of lines ALE algorithm which uses finite elements with elliptic mesh generation and adaptive finite differences for time integration. Thus, the new approach neither starts with a priori idealizations, as has been the case with previous computations, nor is limited to length scales above that set by the wavelength of visible light as in any experimental study. In particular, three distinct responses are identified as the ratio m of the outer fluid's viscosity to the inner fluid's viscosity is varied. For small m, simulations show that the minimum neck radius r initially scales with time τ before breakup as r ˜0.58° (in accord with previous experiments and inviscid fluid models) but that r ˜τ once r becomes sufficiently small. For intermediate and large values of m, r ˜&αcirc;, where the exponent α may not equal one, once again as r becomes sufficiently small.

Foraging swarms as Nash equilibria of dynamic games.

PubMed

Özgüler, Arif Bülent; Yildiz, Aykut

2014-06-01

The question of whether foraging swarms can form as a result of a noncooperative game played by individuals is shown here to have an affirmative answer. A dynamic game played by N agents in 1-D motion is introduced and models, for instance, a foraging ant colony. Each agent controls its velocity to minimize its total work done in a finite time interval. The game is shown to have a unique Nash equilibrium under two different foraging location specifications, and both equilibria display many features of a foraging swarm behavior observed in biological swarms. Explicit expressions are derived for pairwise distances between individuals of the swarm, swarm size, and swarm center location during foraging.

A new transiently chaotic flow with ellipsoid equilibria

NASA Astrophysics Data System (ADS)

Panahi, Shirin; Aram, Zainab; Jafari, Sajad; Pham, Viet-Thanh; Volos, Christos; Rajagopal, Karthikeyan

2018-03-01

In this article, a simple autonomous transiently chaotic flow with cubic nonlinearities is proposed. This system represents some unusual features such as having a surface of equilibria. We shall describe some dynamical properties and behaviours of this system in terms of eigenvalue structures, bifurcation diagrams, time series, and phase portraits. Various behaviours of this system such as periodic and transiently chaotic dynamics can be shown by setting special parameters in proper values. Our system belongs to a newly introduced category of transiently chaotic systems: systems with hidden attractors. Transiently chaotic behaviour of our proposed system has been implemented and tested by the OrCAD-PSpise software. We have found a proper qualitative similarity between circuit and simulation results.

Equilibria of the symmetric collinear restricted four-body problem with radiation pressure

NASA Astrophysics Data System (ADS)

Arribas, M.; Abad, A.; Elipe, A.; Palacios, M.

2016-02-01

In this paper, a restricted four-body problem with radiation pressure is considered. The three primaries are supposed in a collinear central configuration where both masses and both radiation forces of peripheral bodies are equal. After an adequate formulation, the problem is reduced to a tri-parametric one. A complete analysis of the position of equilibria and their stability in the space of parameters is performed.

Reduction and relative equilibria for the two-body problem on spaces of constant curvature

NASA Astrophysics Data System (ADS)

Borisov, A. V.; García-Naranjo, L. C.; Mamaev, I. S.; Montaldi, J.

2018-06-01

We consider the two-body problem on surfaces of constant nonzero curvature and classify the relative equilibria and their stability. On the hyperbolic plane, for each q>0 we show there are two relative equilibria where the masses are separated by a distance q. One of these is geometrically of elliptic type and the other of hyperbolic type. The hyperbolic ones are always unstable, while the elliptic ones are stable when sufficiently close, but unstable when far apart. On the sphere of positive curvature, if the masses are different, there is a unique relative equilibrium (RE) for every angular separation except π /2. When the angle is acute, the RE is elliptic, and when it is obtuse the RE can be either elliptic or linearly unstable. We show using a KAM argument that the acute ones are almost always nonlinearly stable. If the masses are equal, there are two families of relative equilibria: one where the masses are at equal angles with the axis of rotation (`isosceles RE') and the other when the two masses subtend a right angle at the centre of the sphere. The isosceles RE are elliptic if the angle subtended by the particles is acute and is unstable if it is obtuse. At π /2, the two families meet and a pitchfork bifurcation takes place. Right-angled RE are elliptic away from the bifurcation point. In each of the two geometric settings, we use a global reduction to eliminate the group of symmetries and analyse the resulting reduced equations which live on a five-dimensional phase space and possess one Casimir function.

Experimental characterization of powered Fontan hemodynamics in an idealized total cavopulmonary connection model

NASA Astrophysics Data System (ADS)

Kerlo, Anna-Elodie M.; Delorme, Yann T.; Xu, Duo; Frankel, Steven H.; Giridharan, Guruprasad A.; Rodefeld, Mark D.; Chen, Jun

2013-08-01

A viscous impeller pump (VIP) based on the Von Karman viscous pump is specifically designed to provide cavopulmonary assist in a univentricular Fontan circulation. The technology will make it possible to biventricularize the univentricular Fontan circulation. Ideally, it will reduce the number of surgeries required for Fontan conversion from three to one early in life, while simultaneously improving physiological conditions. Later in life, it will provide a currently unavailable means of chronic support for adolescent and adult patients with failing Fontan circulations. Computational fluid dynamics simulations demonstrate that the VIP can satisfactorily augment cavopulmonary blood flow in an idealized total cavopulmonary connection (TCPC). When the VIP is deployed at the TCPC intersection as a static device, it stabilizes the four-way flow pattern and is not obstructive to the flow. Experimental studies are carried out to assess performance, hemodynamic characteristics, and flow structures of the VIP in an idealized TCPC model. Stereoscopic particle image velocimetry is applied using index-matched blood analog. Results show excellent performance of the VIP without cavitation and with reduction of the energy losses. The non-rotating VIP smoothes and accelerates flow, and decreases stresses and turbulence in the TCPC. The rotating VIP generates the desired low-pressure Fontan flow augmentation (0-10 mmHg) while maintaining acceptable stress thresholds.

An exact solution for ideal dam-break floods on steep slopes

USGS Publications Warehouse

Ancey, C.; Iverson, R.M.; Rentschler, M.; Denlinger, R.P.

2008-01-01

The shallow-water equations are used to model the flow resulting from the sudden release of a finite volume of frictionless, incompressible fluid down a uniform slope of arbitrary inclination. The hodograph transformation and Riemann's method make it possible to transform the governing equations into a linear system and then deduce an exact analytical solution expressed in terms of readily evaluated integrals. Although the solution treats an idealized case never strictly realized in nature, it is uniquely well-suited for testing the robustness and accuracy of numerical models used to model shallow-water flows on steep slopes. Copyright 2008 by the American Geophysical Union.

Equilibria of a Two-Person Non-Zerosum Noisy Game of Timing,

DTIC Science & Technology

1981-01-01

AD-A097 158 YALE UNIV NEW HAVEN CT COWLES FOUNDATION FOR RESEARC -ETC F/B 12/1 EQUILIBRIA OF A TWO-PERSON ON-ZEROSUN OISY GAME OF TIMING, CUb .JAN al...pubUo zeleale Distribution Unlimited. 1. Introduction Two toothpaste manufacturers are competing for a larger share of the dentifrice market . Each is...successfully capturing a share of the market , if its product hits the stores first. (This is assuming that the toothpaste is being technologically

Investigation of mucus transport in an idealized lung airway model using multiphase CFD analysis

NASA Astrophysics Data System (ADS)

Rajendran, Rahul; Banerjee, Arindam

2015-11-01

Mucus, a Bingham fluid is transported in the pulmonary airways by consistent beating of the cilia and exhibits a wide range of physical properties in response to the core air flow and various pathological conditions. A better understanding of the interfacial instability is required as it plays a crucial role in gas transport, mixing, mucus clearance and drug delivery. In the current study, mucus is modelled as a Newtonian fluid and the two phase gas-liquid flow in the airways is investigated using an inhomogeneous Eulerian-Eulerian approach. The complex interface between the phases is tracked using the conventional VOF (Volume of Fluid) method. Results from our CFD simulations which are performed in idealized single and double bifurcation geometries will be presented and the influence of airflow rate, mucus layer thickness, mucus viscosity, airway geometry (branching & diameter) and surface tension on mucus flow behavior will be discussed. Mean mucus layer thickness, pressure drop due to momentum transfer & increased airway resistance, mucus transport speed and the flow morphology will be compared to existing experimental and theoretical data.

New closed analytical solutions for geometrically thick fluid tori around black holes. Numerical evolution and the onset of the magneto-rotational instability

NASA Astrophysics Data System (ADS)

Witzany, V.; Jefremov, P.

2018-06-01

Context. When a black hole is accreting well below the Eddington rate, a geometrically thick, radiatively inefficient state of the accretion disk is established. There is a limited number of closed-form physical solutions for geometrically thick (nonselfgravitating) toroidal equilibria of perfect fluids orbiting a spinning black hole, and these are predominantly used as initial conditions for simulations of accretion in the aforementioned mode. However, different initial configurations might lead to different results and thus observational predictions drawn from such simulations. Aims: We aim to expand the known equilibria by a number of closed multiparametric solutions with various possibilities of rotation curves and geometric shapes. Then, we ask whether choosing these as initial conditions influences the onset of accretion and the asymptotic state of the disk. Methods: We have investigated a set of examples from the derived solutions in detail; we analytically estimate the growth of the magneto-rotational instability (MRI) from their rotation curves and evolve the analytically obtained tori using the 2D magneto-hydrodynamical code HARM. Properties of the evolutions are then studied through the mass, energy, and angular-momentum accretion rates. Results: The rotation curve has a decisive role in the numerical onset of accretion in accordance with our analytical MRI estimates: in the first few orbital periods, the average accretion rate is linearly proportional to the initial MRI rate in the toroids. The final state obtained from any initial condition within the studied class after an evolution of ten or more orbital periods is mostly qualitatively identical and the quantitative properties vary within a single order of magnitude. The average values of the energy of the accreted fluid have an irregular dependency on initial data, and in some cases fluid with energies many times its rest mass is systematically accreted.

From the ideal market to the ideal clinic: constructing a normative standard of fairness for human subjects research.

PubMed

Phillips, Trisha

2011-02-01

Preventing exploitation in human subjects research requires a benchmark of fairness against which to judge the distribution of the benefits and burdens of a trial. This paper proposes the ideal market and its fair market price as a criterion of fairness. The ideal market approach is not new to discussions about exploitation, so this paper reviews Wertheimer's inchoate presentation of the ideal market as a principle of fairness, attempt of Emanuel and colleagues to apply the ideal market to human subjects research, and Ballantyne's criticisms of both the ideal market and the resulting benchmark of fairness. It argues that the criticism of this particular benchmark is on point, but the rejection of the ideal market is mistaken. After presenting a complete account of the ideal market, this paper proposes a new method for applying the ideal market to human subjects research and illustrates the proposal by considering a sample case.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheviakov, Alexei F., E-mail: chevaikov@math.usask.ca

Partial differential equations of the form divN=0, N{sub t}+curl M=0 involving two vector functions in R{sup 3} depending on t, x, y, z appear in different physical contexts, including the vorticity formulation of fluid dynamics, magnetohydrodynamics (MHD) equations, and Maxwell's equations. It is shown that these equations possess an infinite family of local divergence-type conservation laws involving arbitrary functions of space and time. Moreover, it is demonstrated that the equations of interest have a rather special structure of a lower-degree (degree two) conservation law in R{sup 4}(t,x,y,z). The corresponding potential system has a clear physical meaning. For the Maxwell's equations,more » it gives rise to the scalar electric and the vector magnetic potentials; for the vorticity equations of fluid dynamics, the potentialization inverts the curl operator to yield the fluid dynamics equations in primitive variables; for MHD equations, the potential equations yield a generalization of the Galas-Bogoyavlenskij potential that describes magnetic surfaces of ideal MHD equilibria. The lower-degree conservation law is further shown to yield curl-type conservation laws and determined potential equations in certain lower-dimensional settings. Examples of new nonlocal conservation laws, including an infinite family of nonlocal material conservation laws of ideal time-dependent MHD equations in 2+1 dimensions, are presented.« less

Impact on a Compressible Fluid

NASA Technical Reports Server (NTRS)

Egorov, L. T.

1958-01-01

Upon impact of a solid body on the plane surface of a fluid, there occurs on the vetted surface of the body an abrupt pressure rise which propagates into both media with the speed of sound. Below, we assume the case where the speed of propagation of sound in the body which falls on the surface of the fluid may be regarded as infinitely large in comparison with the speed of propagation of sound in the fluid; that is, we shall assume that the falling body is absolutely rigid. IN this case, the entire relative speed of the motion which takes place at the beginning of the impact is absorbed by the fluid. The hydrodynamic pressures arising thereby are propagated from the contact surface within the fluid with the speed of sound in the form of compression and expansion waves and are gradually damped. After this, they are dispersed like impact pressures, reach ever larger regions of the fluid remote fran the body and became equal to zero; in the fluid there remain hydrodynamic pressures corresponding to the motion of the body after the impact. Neglecting the forces of viscosity and taking into account, furthermore, that the motion of the fluid begins from a state of rest, according to Thomson's theorem, we may consider the motion of an ideal compressible fluid in the process of impact to be potential. We examine the case of impact upon the surface of a ccmpressible fluid of a flat plate of infinite extent or of a body, the immersed part of the surface of which may be called approximately flat. In this report we discuss the first phase of the impact pressure on the surface of a fluid, prior to the appearance of a cavity, since at this stage the hydrodynamic pressures reach their maximum values. Observations, after the fall of the bodies on the surface of the fluid, show that the free surface of the fluid at this stage is almost completely at rest if one does not take into account the small rise in the neighborhood of the boundaries of the impact surface.

Idealized Cloud-System Resolving Modeling for Tropical Convection Studies

NASA Astrophysics Data System (ADS)

Anber, Usama M.

A three-dimensional limited-domain Cloud-Resolving Model (CRM) is used in idealized settings to study the interaction between tropical convection and the large scale dynamics. The model domain is doubly periodic and the large-scale circulation is parameterized using the Weak Temperature Gradient (WTG) Approximation and Damped Gravity Wave (DGW) methods. The model simulations fall into two main categories: simulations with a prescribed radiative cooling profile, and others in which radiative cooling profile interacts with clouds and water vapor. For experiments with a prescribed radiative cooling profile, radiative heating is taken constant in the vertical in the troposphere. First, the effect of turbulent surface fluxes and radiative cooling on tropical deep convection is studied. In the precipitating equilibria, an increment in surface fluxes produces a greater increase in precipitation than an equal increment in column-integrated radiative heating. The gross moist stability remains close to constant over a wide range of forcings. With dry initial conditions, the system exhibits hysteresis, and maintains a dry state with for a wide range of net energy inputs to the atmospheric column under WTG. However, for the same forcings the system admits a rainy state when initialized with moist conditions, and thus multiple equilibria exist under WTG. When the net forcing is increased enough that simulations, which begin dry, eventually develop precipitation. DGW, on the other hand, does not have the tendency to develop multiple equilibria under the same conditions. The effect of vertical wind shear on tropical deep convection is also studied. The strength and depth of the shear layer are varied as control parameters. Surface fluxes are prescribed. For weak wind shear, time-averaged rainfall decreases with shear and convection remains disorganized. For larger wind shear, rainfall increases with shear, as convection becomes organized into linear mesoscale systems. This non

Ideals as Anchors for Relationship Experiences

PubMed Central

Frye, Margaret; Trinitapoli, Jenny

2016-01-01

Research on young-adult sexuality in sub-Saharan Africa typically conceptualizes sex as an individual-level risk behavior. We introduce a new approach that connects the conditions surrounding the initiation of sex with subsequent relationship well-being, examines relationships as sequences of interdependent events, and indexes relationship experiences to individually held ideals. New card-sort data from southern Malawi capture young women’s relationship experiences and their ideals in a sequential framework. Using optimal matching, we measure the distance between ideal and experienced relationship sequences to (1) assess the associations between ideological congruence and perceived relationship well-being, (2) compare this ideal-based approach to other experience-based alternatives, and (3) identify individual- and couple-level correlates of congruence between ideals and experiences in the romantic realm. We show that congruence between ideals and experiences conveys relationship well-being along four dimensions: expressions of love and support, robust communication habits, perceived biological safety, and perceived relationship stability. We further show that congruence is patterned by socioeconomic status and supported by shared ideals within romantic dyads. We argue that conceiving of ideals as anchors for how sexual experiences are manifest advances current understandings of romantic relationships, and we suggest that this approach has applications for other domains of life. PMID:27110031

Ideals and Category Typicality

ERIC Educational Resources Information Center

Kim, ShinWoo; Murphy, Gregory L.

2011-01-01

Barsalou (1985) argued that exemplars that serve category goals become more typical category members. Although this claim has received support, we investigated (a) whether categories have a single ideal, as negatively valenced categories (e.g., cigarette) often have conflicting goals, and (b) whether ideal items are in fact typical, as they often…

Ideal AFROC and FROC observers.

PubMed

Khurd, Parmeshwar; Liu, Bin; Gindi, Gene

2010-02-01

Detection of multiple lesions in images is a medically important task and free-response receiver operating characteristic (FROC) analyses and its variants, such as alternative FROC (AFROC) analyses, are commonly used to quantify performance in such tasks. However, ideal observers that optimize FROC or AFROC performance metrics have not yet been formulated in the general case. If available, such ideal observers may turn out to be valuable for imaging system optimization and in the design of computer aided diagnosis techniques for lesion detection in medical images. In this paper, we derive ideal AFROC and FROC observers. They are ideal in that they maximize, amongst all decision strategies, the area, or any partial area, under the associated AFROC or FROC curve. Calculation of observer performance for these ideal observers is computationally quite complex. We can reduce this complexity by considering forms of these observers that use false positive reports derived from signal-absent images only. We also consider a Bayes risk analysis for the multiple-signal detection task with an appropriate definition of costs. A general decision strategy that minimizes Bayes risk is derived. With particular cost constraints, this general decision strategy reduces to the decision strategy associated with the ideal AFROC or FROC observer.

Astrophysical fluid dynamics

NASA Astrophysics Data System (ADS)

Ogilvie, Gordon I.

2016-06-01

> These lecture notes and example problems are based on a course given at the University of Cambridge in Part III of the Mathematical Tripos. Fluid dynamics is involved in a very wide range of astrophysical phenomena, such as the formation and internal dynamics of stars and giant planets, the workings of jets and accretion discs around stars and black holes and the dynamics of the expanding Universe. Effects that can be important in astrophysical fluids include compressibility, self-gravitation and the dynamical influence of the magnetic field that is `frozen in' to a highly conducting plasma. The basic models introduced and applied in this course are Newtonian gas dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The mathematical structure of the governing equations and the associated conservation laws are explored in some detail because of their importance for both analytical and numerical methods of solution, as well as for physical interpretation. Linear and nonlinear waves, including shocks and other discontinuities, are discussed. The spherical blast wave resulting from a supernova, and involving a strong shock, is a classic problem that can be solved analytically. Steady solutions with spherical or axial symmetry reveal the physics of winds and jets from stars and discs. The linearized equations determine the oscillation modes of astrophysical bodies, as well as their stability and their response to tidal forcing.

Lagrangian averages, averaged Lagrangians, and the mean effects of fluctuations in fluid dynamics.

PubMed

Holm, Darryl D.

2002-06-01

We begin by placing the generalized Lagrangian mean (GLM) equations for a compressible adiabatic fluid into the Euler-Poincare (EP) variational framework of fluid dynamics, for an averaged Lagrangian. This is the Lagrangian averaged Euler-Poincare (LAEP) theorem. Next, we derive a set of approximate small amplitude GLM equations (glm equations) at second order in the fluctuating displacement of a Lagrangian trajectory from its mean position. These equations express the linear and nonlinear back-reaction effects on the Eulerian mean fluid quantities by the fluctuating displacements of the Lagrangian trajectories in terms of their Eulerian second moments. The derivation of the glm equations uses the linearized relations between Eulerian and Lagrangian fluctuations, in the tradition of Lagrangian stability analysis for fluids. The glm derivation also uses the method of averaged Lagrangians, in the tradition of wave, mean flow interaction. Next, the new glm EP motion equations for incompressible ideal fluids are compared with the Euler-alpha turbulence closure equations. An alpha model is a GLM (or glm) fluid theory with a Taylor hypothesis closure. Such closures are based on the linearized fluctuation relations that determine the dynamics of the Lagrangian statistical quantities in the Euler-alpha equations. Thus, by using the LAEP theorem, we bridge between the GLM equations and the Euler-alpha closure equations, through the small-amplitude glm approximation in the EP variational framework. We conclude by highlighting a new application of the GLM, glm, and alpha-model results for Lagrangian averaged ideal magnetohydrodynamics. (c) 2002 American Institute of Physics.

Fluid and structure coupling analysis of the interaction between aqueous humor and iris.

PubMed

Wang, Wenjia; Qian, Xiuqing; Song, Hongfang; Zhang, Mindi; Liu, Zhicheng

2016-12-28

Glaucoma is the primary cause of irreversible blindness worldwide associated with high intraocular pressure (IOP). Elevated intraocular pressure will affect the normal aqueous humor outflow, resulting in deformation of iris. However, the deformation ability of iris is closely related to its material properties. Meanwhile, the passive deformation of the iris aggravates the pupillary block and angle closure. The nature of the interaction mechanism of iris deformation and aqueous humor fluid flow has not been fully understood and has been somewhat a controversial issue. The purpose here was to study the effect of IOP, localization, and temperature on the flow of the aqueous humor and the deformation of iris interacted by aqueous humor fluid flow. Based on mechanisms of aqueous physiology and fluid dynamics, 3D model of anterior chamber (AC) was constructed with the human anatomical parameters as a reference. A 3D idealized standard geometry of anterior segment of human eye was performed. Enlarge the size of the idealization geometry model 5 times to create a simulation device by using 3D printing technology. In this paper, particle image velocimetry technology is applied to measure the characteristic of fluid outflow in different inlet velocity based on the device. Numerically calculations were made by using ANSYS 14.0 Finite Element Analysis. Compare of the velocity distributions to confirm the validity of the model. The fluid structure interaction (FSI) analysis was carried out in the valid geometry model to study the aqueous flow and iris change. In this paper, the validity of the model is verified through computation and comparison. The results indicated that changes of gravity direction of model significantly affected the fluid dynamics parameters and the temperature distribution in anterior chamber. Increased pressure and the vertical position increase the velocity of the aqueous humor fluid flow, with the value increased of 0.015 and 0.035 mm/s. The results

Optimal probes for withdrawal of uncontaminated fluid samples

NASA Astrophysics Data System (ADS)

Sherwood, J. D.

2005-08-01

Withdrawal of fluid by a composite probe pushed against the face z =0 of a porous half-space z >0 is modeled assuming incompressible Darcy flow. The probe is circular, of radius a, with an inner sampling section of radius αa and a concentric outer guard probe αa fluid 1, and the region z >βa is saturated with fluid 2; the two fluids have the same viscosity. It is assumed that the interface between the two fluids is sharp and remains so as it moves through the rock. The pressure in the probe is lower than that of the pore fluid in the rock, so that the fluid interface is convected with the fluids towards the probe. This idealized axisymmetric problem is solved numerically, and it is shown that an analysis based on far-field spherical flow towards a point sink is a good approximation when the nondimensional depth of fluid 1 is large, i.e., β ≫1. The inner sampling probe eventually produces pure fluid 2, and this technique has been proposed for sampling pore fluids in rock surrounding an oil well [A. Hrametz, C. Gardner, M. Wais, and M. Proett, U.S. Patent No. 6,301,959 B1 (16 October 2001)]. Fluid 1 is drilling fluid filtrate, which has displaced the original pore fluid (fluid 2), a pure sample of which is required. The time required to collect an uncontaminated sample of original pore fluid can be minimized by a suitable choice of the probe geometry α [J. Sherwood, J. Fitzgerald and B. Hill, U.S. Patent No. 6,719,049 B2 (13 April 2004)]. It is shown that the optimal choice of α depends on the depth of filtrate invasion β and the volume of sample required.

Undergraduate Teaching of Ideal and Real Fluid Flows: The Value of Real-World Experimental Projects

ERIC Educational Resources Information Center

Baldock, Tom E.; Chanson, Hubert

2006-01-01

This paper describes the pedagogical impact of real-world experimental projects undertaken as part of an advanced undergraduate fluid mechanics subject at an Australian university. The projects have been organized to complement traditional lectures and introduce students to the challenges of professional design, physical modelling, data collection…

Phase equilibria and crystal chemistry of rubidium niobates and rubidium tantalates

NASA Technical Reports Server (NTRS)

Minor, D. B.; Roth, R. S.; Parker, H. S.; Brower, W. S.

1977-01-01

The phase equilibria relations and crystal chemistry of portions of the Rb2O-Nb2O5 and Rb2O-Ta2O5 systems were investigated for structures potentially useful as ionic conductors. A hexagonal tungsten bronze-type (HTB) structure was found in both systems as well as three hexagonal phases with mixed HTB-pyrochlore type structures. Ion exchange experiments between various alkali ions are described for several phases. Unit cell dimensions and X-ray diffraction powder patterns are reported.

Oscillations and Multiple Equilibria in Microvascular Blood Flow.

PubMed

Karst, Nathaniel J; Storey, Brian D; Geddes, John B

2015-07-01

We investigate the existence of oscillatory dynamics and multiple steady-state flow rates in a network with a simple topology and in vivo microvascular blood flow constitutive laws. Unlike many previous analytic studies, we employ the most biologically relevant models of the physical properties of whole blood. Through a combination of analytic and numeric techniques, we predict in a series of two-parameter bifurcation diagrams a range of dynamical behaviors, including multiple equilibria flow configurations, simple oscillations in volumetric flow rate, and multiple coexistent limit cycles at physically realizable parameters. We show that complexity in network topology is not necessary for complex behaviors to arise and that nonlinear rheology, in particular the plasma skimming effect, is sufficient to support oscillatory dynamics similar to those observed in vivo.

Si-F complexing in aqueous fluids: experimental study and implications for transport of immobile elements

NASA Astrophysics Data System (ADS)

Dolejš, David

2014-05-01

Intepretation of fluid-mineral interaction mechanisms and hydrothermal fluxes requires knowledge of predominant solubility and speciation reactions and their thermodynamic properties. Fluorine represents a hard electron donor, capable of complexing and transporting high-field strength elements, which are traditionally considered to be immobile. Reactions responsible for element mobility have general form MOx + y HF (aq) + x - y H2O = M(OH)2x-yFy (aq), and their extent and transport efficiency relies on hydrogen fluoride activity. In natural fluids, a[HF] is controlled by various fluorination equilibria including neutralization of silicates with consequent formation of silicohydroxyfluoride complexes. Quartz solubility in HF-H2O fluids was experimentally determined at 400-800 oC and 100-200 MPa using rapid-quench cold-seal pressure vessels and the mineral weight-loss method. Quartz solubility significantly increases in the presence of hydrogen fluoride: at 400 oC and 100 MPa, dissolved SiO2 ranges from 0.18 wt. % in pure H2O to 12.2 wt. % at 8.3 wt. % F in the fluid, whereas at 800 oC and 200 MPa it rises from 1.51 wt. % in pure H2O to 15.3 wt. % at 8.0 wt. % F in the fluid. The isobaric solubilities of quartz appear to be temperature-independent, i.e., effects of temperature vs. fluid density on the solubility are counteracting. The experimental data are described by the density model: log m[SiO2] = a + blog ρ + clog m[F] + dT , where a = -1.049 mol kg-1, b = 0.816 mol cm-3, c = 0.802 and d = 1.256 · 10-3 mol kg-1 K-1. Solubility isotherms have similar d(log m[SiO2])/d(log m[F]) slopes over the entire range of conditions indicating that Si(OH)2F2 is the major aqueous species. Several factors promote breakdown of silicohydroxyfluoride complexes and precipitation of silica solute: (i) decreasing temperature and pressure, i.e., fluid ascent and cooling and/or (ii) neutralization and increase in the alkali/H ratio of fluids during alteration reactions or removal of

Similarity Laws for the Lines of Ideal Free Energy and Chemical Potential in Supercritical Fluids.

PubMed

Apfelbaum, E M; Vorob'ev, V S

2017-09-21

We have found the curves on the density-temperature plane, along which the values of free energy and chemical potential correspond to ideal gas quantities. At first, we have applied the van der Waals equation to construct them and to derive their equations. Then we have shown that the same lines for real substances (Ar, N 2 , CH 4 , SF 6 , H 2 , H 2 O) and for the model Lennard-Jones system constructed on the basis of the measurements data and calculations are well matched with the derived equations. The validity and deviations from the obtained similarity laws are discussed.

Yielding to Stress: Recent Developments in Viscoplastic Fluid Mechanics

NASA Astrophysics Data System (ADS)

Balmforth, Neil J.; Frigaard, Ian A.; Ovarlez, Guillaume

2014-01-01

The archetypal feature of a viscoplastic fluid is its yield stress: If the material is not sufficiently stressed, it behaves like a solid, but once the yield stress is exceeded, the material flows like a fluid. Such behavior characterizes materials common in industries such as petroleum and chemical processing, cosmetics, and food processing and in geophysical fluid dynamics. The most common idealization of a viscoplastic fluid is the Bingham model, which has been widely used to rationalize experimental data, even though it is a crude oversimplification of true rheological behavior. The popularity of the model is in its apparent simplicity. Despite this, the sudden transition between solid-like behavior and flow introduces significant complications into the dynamics, which, as a result, has resisted much analysis. Over recent decades, theoretical developments, both analytical and computational, have provided a better understanding of the effect of the yield stress. Simultaneously, greater insight into the material behavior of real fluids has been afforded by advances in rheometry. These developments have primed us for a better understanding of the various applications in the natural and engineering sciences.

Simple equations to simulate closed-loop recycling liquid-liquid chromatography: Ideal and non-ideal recycling models.

PubMed

Kostanyan, Artak E

2015-12-04

The ideal (the column outlet is directly connected to the column inlet) and non-ideal (includes the effects of extra-column dispersion) recycling equilibrium-cell models are used to simulate closed-loop recycling counter-current chromatography (CLR CCC). Simple chromatogram equations for the individual cycles and equations describing the transport and broadening of single peaks and complex chromatograms inside the recycling closed-loop column for ideal and non-ideal recycling models are presented. The extra-column dispersion is included in the theoretical analysis, by replacing the recycling system (connecting lines, pump and valving) by a cascade of Nec perfectly mixed cells. To evaluate extra-column contribution to band broadening, two limiting regimes of recycling are analyzed: plug-flow, Nec→∞, and maximum extra-column dispersion, Nec=1. Comparative analysis of ideal and non-ideal models has shown that when the volume of the recycling system is less than one percent of the column volume, the influence of the extra-column processes on the CLR CCC separation may be neglected. Copyright © 2015 Elsevier B.V. All rights reserved.

A Generalized Fluid System Simulation Program to Model Flow Distribution in Fluid Networks

NASA Technical Reports Server (NTRS)

Majumdar, Alok; Bailey, John W.; Schallhorn, Paul; Steadman, Todd

1998-01-01

This paper describes a general purpose computer program for analyzing steady state and transient flow in a complex network. The program is capable of modeling phase changes, compressibility, mixture thermodynamics and external body forces such as gravity and centrifugal. The program's preprocessor allows the user to interactively develop a fluid network simulation consisting of nodes and branches. Mass, energy and specie conservation equations are solved at the nodes; the momentum conservation equations are solved in the branches. The program contains subroutines for computing "real fluid" thermodynamic and thermophysical properties for 33 fluids. The fluids are: helium, methane, neon, nitrogen, carbon monoxide, oxygen, argon, carbon dioxide, fluorine, hydrogen, parahydrogen, water, kerosene (RP-1), isobutane, butane, deuterium, ethane, ethylene, hydrogen sulfide, krypton, propane, xenon, R-11, R-12, R-22, R-32, R-123, R-124, R-125, R-134A, R-152A, nitrogen trifluoride and ammonia. The program also provides the options of using any incompressible fluid with constant density and viscosity or ideal gas. Seventeen different resistance/source options are provided for modeling momentum sources or sinks in the branches. These options include: pipe flow, flow through a restriction, non-circular duct, pipe flow with entrance and/or exit losses, thin sharp orifice, thick orifice, square edge reduction, square edge expansion, rotating annular duct, rotating radial duct, labyrinth seal, parallel plates, common fittings and valves, pump characteristics, pump power, valve with a given loss coefficient, and a Joule-Thompson device. The system of equations describing the fluid network is solved by a hybrid numerical method that is a combination of the Newton-Raphson and successive substitution methods. This paper also illustrates the application and verification of the code by comparison with Hardy Cross method for steady state flow and analytical solution for unsteady flow.

Computation of Phase Equilibria, State Diagrams and Gas/Particle Partitioning of Mixed Organic-Inorganic Aerosols

NASA Astrophysics Data System (ADS)

Zuend, A.; Marcolli, C.; Peter, T.

2009-04-01

The chemical composition of organic-inorganic aerosols is linked to several processes and specific topics in the field of atmospheric aerosol science. Photochemical oxidation of organics in the gas phase lowers the volatility of semi-volatile compounds and contributes to the particulate matter by gas/particle partitioning. Heterogeneous chemistry and changes in the ambient relative humidity influence the aerosol composition as well. Molecular interactions between condensed phase species show typically non-ideal thermodynamic behavior. Liquid-liquid phase separations into a mainly polar, aqueous and a less polar, organic phase may considerably influence the gas/particle partitioning of semi-volatile organics and inorganics (Erdakos and Pankow, 2004; Chang and Pankow, 2006). Moreover, the phases present in the aerosol particles feed back on the heterogeneous, multi-phase chemistry, influence the scattering and absorption of radiation and affect the CCN ability of the particles. Non-ideal thermodynamic behavior in mixtures is usually described by an expression for the excess Gibbs energy, enabling the calculation of activity coefficients. We use the group-contribution model AIOMFAC (Zuend et al., 2008) to calculate activity coefficients, chemical potentials and the total Gibbs energy of mixed organic-inorganic systems. This thermodynamic model was combined with a robust global optimization module to compute potential liquid-liquid (LLE) and vapor-liquid-liquid equilibria (VLLE) as a function of particle composition at room temperature. And related to that, the gas/particle partitioning of semi-volatile components. Furthermore, we compute the thermodynamic stability (spinodal limits) of single-phase solutions, which provides information on the process type and kinetics of a phase separation. References Chang, E. I. and Pankow, J. F.: Prediction of activity coefficients in liquid aerosol particles containing organic compounds, dissolved inorganic salts, and water - Part

Hydrogen Absorption in Fluids: An Unexplored Solution for Onboard Hydrogen Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, G D

Adoption of hydrogen (H{sub 2}) vehicles has been advocated for decades as an ecological ideal, capable of eliminating petroleum consumption as well as tail-pipe air pollution and carbon dioxide (CO{sub 2}) from automobiles. Storing sufficient hydrogen fuel onboard still remains a great technological challenge, despite recent advances in lightweight automotive materials, hybrid-electric drivetrains and fuel cells enabling 60-100 mpg equivalent H{sub 2}-fueled automobiles. Future onboard hydrogen storage choices will be pivotal, with lasting strategic consequences for the eventual scale, shape, security, investment requirements, and energy intensity of the H{sub 2} refueling infrastructure, in addition to impacts on automotive design, cost,more » range, performance, and safety. Multiple hydrogen storage approaches have been examined and deployed onboard prototype automobiles since the 1970's. These include storing H{sub 2} as a cryogenic liquid (LH{sub 2}) at temperatures of 20-25 Kelvin, compressing room temperature H{sub 2} gas to pressures as high as 10,000 psi, and reversible chemical absorption storage within powdered metal hydrides (e.g. LaNi{sub 5}H{sub 6}, TiFeH{sub 2}, MgH{sub 2}, NaAlH{sub 4}) which evolve H{sub 2} when warmed. Each of these approaches face well-known fundamental physical limits (thermal endurance, volume, and weight, respectively). This report details preliminary experiments investigating the potential of a new approach to H{sub 2} storage: absorption in fluids, specifically liquid nitrogen (LN{sub 2}). N{sub 2} was chosen for this study because it offers unique advantages as an inert but lightweight solvent with high hydrogen solubility and is an abundant atmospheric component. H{sub 2} absorbed in liquid nitrogen (LN{sub 2}) can be lighter than metal hydrides, with greater thermal endurance than cryogenic H{sub 2} or LH{sub 2}, while being more compact than ambient compressed H{sub 2}. Previous researchers have examined H{sub 2} mixed

Symmetry breaking in optimal timing of traffic signals on an idealized two-way street.

PubMed

Panaggio, Mark J; Ottino-Löffler, Bertand J; Hu, Peiguang; Abrams, Daniel M

2013-09-01

Simple physical models based on fluid mechanics have long been used to understand the flow of vehicular traffic on freeways; analytically tractable models of flow on an urban grid, however, have not been as extensively explored. In an ideal world, traffic signals would be timed such that consecutive lights turned green just as vehicles arrived, eliminating the need to stop at each block. Unfortunately, this "green-wave" scenario is generally unworkable due to frustration imposed by competing demands of traffic moving in different directions. Until now this has typically been resolved by numerical simulation and optimization. Here, we develop a theory for the flow in an idealized system consisting of a long two-way road with periodic intersections. We show that optimal signal timing can be understood analytically and that there are counterintuitive asymmetric solutions to this signal coordination problem. We further explore how these theoretical solutions degrade as traffic conditions vary and automotive density increases.

Symmetry breaking in optimal timing of traffic signals on an idealized two-way street

NASA Astrophysics Data System (ADS)

Panaggio, Mark J.; Ottino-Löffler, Bertand J.; Hu, Peiguang; Abrams, Daniel M.

2013-09-01

Simple physical models based on fluid mechanics have long been used to understand the flow of vehicular traffic on freeways; analytically tractable models of flow on an urban grid, however, have not been as extensively explored. In an ideal world, traffic signals would be timed such that consecutive lights turned green just as vehicles arrived, eliminating the need to stop at each block. Unfortunately, this “green-wave” scenario is generally unworkable due to frustration imposed by competing demands of traffic moving in different directions. Until now this has typically been resolved by numerical simulation and optimization. Here, we develop a theory for the flow in an idealized system consisting of a long two-way road with periodic intersections. We show that optimal signal timing can be understood analytically and that there are counterintuitive asymmetric solutions to this signal coordination problem. We further explore how these theoretical solutions degrade as traffic conditions vary and automotive density increases.

The Spectral Web of stationary plasma equilibria. II. Internal modes

NASA Astrophysics Data System (ADS)

Goedbloed, J. P.

2018-03-01

The new method of the Spectral Web to calculate the spectrum of waves and instabilities of plasma equilibria with sizeable flows, developed in the preceding Paper I [Goedbloed, Phys. Plasmas 25, 032109 (2018)], is applied to a collection of classical magnetohydrodynamic instabilities operating in cylindrical plasmas with shear flow or rotation. After a review of the basic concepts of the complementary energy giving the solution path and the conjugate path, which together constitute the Spectral Web, the cylindrical model is presented and the spectral equations are derived. The first example concerns the internal kink instabilities of a cylindrical force-free magnetic field of constant α subjected to a parabolic shear flow profile. The old stability diagram and the associated growth rate calculations for static equilibria are replaced by a new intricate stability diagram and associated complex growth rates for the stationary model. The power of the Spectral Web method is demonstrated by showing that the two associated paths in the complex ω-plane nearly automatically guide to the new class of global Alfvén instabilities of the force-free configuration that would have been very hard to predict by other methods. The second example concerns the Rayleigh-Taylor instability of a rotating theta-pinch. The old literature is revisited and shown to suffer from inconsistencies that are remedied. The most global n = 1 instability and a cluster sequence of more local but much more unstable n =2 ,3 ,…∞ modes are located on separate solution paths in the hydrodynamic (HD) version of the instability, whereas they merge in the MHD version. The Spectral Web offers visual demonstration of the central position the HD flow continuum and of the MHD Alfvén and slow magneto-sonic continua in the respective spectra by connecting the discrete modes in the complex plane by physically meaningful curves towards the continua. The third example concerns the magneto-rotational instability

Acid-base equilibria inside amine-functionalized mesoporous silica.

PubMed

Yamaguchi, Akira; Namekawa, Manato; Kamijo, Toshio; Itoh, Tetsuji; Teramae, Norio

2011-04-15

Acid-base equilibria and effective proton concentration inside a silica mesopore modified with a trimethyl ammonium (TMAP) layer were studied by steady-state fluorescence experiments. The mesoporous silica with a dense TMAP layer (1.4 molecules/nm(2)) was prepared by a post grafting of N-trimethoxysilylpropyl-N,N,N-trimethylammonium at surfactant-templated mesoporous silica (diameter of silica framework =3.1 nm). The resulting TMAP-modified mesoporous silica strongly adsorbed of anionic fluorescence indicator dyes (8-hydroxypyrene-1,3,6-trisulfonate (pyranine), 8-aminopyrene-1,3,6-trisulfonate (APTS), 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid disulfuric acid (TPPS), 2-naphthol-3,6-disulfonate (2NT)) and fluorescence excitation spectra of these dyes within TMAP-modified mesoporous silica were measured by varying the solution pH. The fluorescence experiments revealed that the acid-base equilibrium reactions of all pH indicator dyes within the TMAP-modified silica mesopore were quite different from those in bulk water. From the analysis of the acid-base equilibrium of pyranine, the following relationships between solution pH (pH(bulk)) and the effective proton concentration inside the pore (pH(pore)) were obtained: (1) shift of pH(pore) was 1.8 (ΔpH(pore)=1.8) for the pH(bulk) change from 2.1 to 9.1 (ΔpH(bulk)=7.0); (2) pH(pore) was not simply proportional to pH(bulk); (3) the inside of the TMAP-modified silica mesopore was suggested to be in a weak acidic or neutral condition when pH(bulk) was changed from 2.0 to 9.1. Since these relationships between pH(bulk) and pH(pore) could explain the acid-base equilibria of other pH indicator dyes (APTS, TPPS, 2NT), these relationships were inferred to describe the effective proton concentration inside the TMAP-modified silica mesopore. © 2011 American Chemical Society

An experimental study of the effect of temperature, fluid chemistry and reaction rate on Sr-Ca partitioning in anhydrite: Implications for subseafloor hydrothermal alteration processes

NASA Astrophysics Data System (ADS)

Syverson, D.; Seyfried, W. E.

2010-12-01

Anhydrite (CaSO4) is an important mineral in subseafloor hydrothermal systems. Its solubility likely plays a role in controlling mass transfer reactions in the relatively low temperature and ultramafic-hosted Lost City Hydrothermal Field (LCHF), while also precipitating from seawater during recharge of more widespread high-temperature hydrothermal systems at mid-ocean ridges. Strontium partitions into anhydrite, although the magnitude and mechanism by which this occurs, is still unclear, as is the effect of precipitation rate. In the absence of these data it is not possible to predict accurately the geochemical implications of Sr/Ca ratios of vent fluids. Accordingly, the potential usefulness of these data to constrain temperature, and as a means to understand the flux of seawater derived Sr into deeper portions of subseafloor hydrothermal systems, is limited. Here we report results of experiments designed to assess Ca-Sr exchange during anhydrite-fluid reaction as a function of temperature, fluid chemistry and distance from equilibrium. Anhydrite used for the experiments was synthesized to avoid compositional impurities and annealed to achieve grain sizes (10-100 micron) and uniform crystalline properties. NaCl fluids (0.55 m) with known Sr/Ca ratios were used for the experiments. Experiments were performed at 200° and 250°C, 500 bars, while time series changes in fluid chemistry were monitored by fluid sampling at experimental conditions. Isobaric temperature change as well as chemical perturbation by addition of fluids with anomalous Sr/Ca ratio permitted phase equilibria to be unambiguously assed. Moreover, the chemical perturbation experiments provided information on the effect of rate of reaction on Sr-Ca exchange. Isobaric temperature jumps demonstrate that initially anhydrite precipitation incorporates Sr preferentially. With further reaction progress and approach to equilibrium Sr uptake by anhydrite recrystallization becomes less effective. Long

Experimental technique for studying high-temperature phase equilibria in reactive molten metal based systems

NASA Astrophysics Data System (ADS)

Ermoline, Alexandre

The general objective of this work is to develop an experimental technique for studying the high-temperature phase compositions and phase equilibria in molten metal-based binary and ternary systems, such as Zr-O-N, B-N-O, Al-O, and others. A specific material system of Zr-O-N was selected for studying and testing this technique. The information about the high-temperature phase equilibria in reactive metal-based systems is scarce and their studying is difficult because of chemical reactions occurring between samples and essentially any container materials, and causing contamination of the system. Containerless microgravity experiments for studying equilibria in molten metal-gas systems were designed to be conducted onboard of a NASA KC-135 aircraft flying parabolic trajectories. A uniaxial apparatus suitable for acoustic levitation, laser heating, and splat quenching of small samples was developed and equipped with computer-based controller and optical diagnostics. Normal-gravity tests were conducted to determine the most suitable operating parameters of the levitator by direct observations of the levitated samples, as opposed to more traditional pressure mapping of the acoustic field. The size range of samples that could be reliably heated and quenched in this setup was determined to be on the order of 1--3 mm. In microgravity experiments, small spherical specimens (1--2 mm diameter), prepared as pressed, premixed solid components, ZrO2, ZrN, and Zr powders, were acoustically levitated inside an argon-filled chamber at one atmosphere and heated by a CO2 laser. The levitating samples could be continuously laser heated for about 1 sec, resulting in local sample melting. The sample stability in the vertical direction was undisturbed by simultaneous laser heating. Oscillations of the levitating sample in the horizontal direction increased while it was heated, which eventually resulted in the movement of the sample away from its stable levitation position and the laser

3D Equilibrium Effects Due to RMP Application on DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

S. Lazerson, E. Lazarus, S. Hudson, N. Pablant and D. Gates

2012-06-20

The mitigation and suppression of edge localized modes (ELMs) through application of resonant magnetic perturbations (RMPs) in Tokamak plasmas is a well documented phenomenon [1]. Vacuum calculations suggest the formation of edge islands and stochastic regions when RMPs are applied to the axisymmetric equilibria. Self-consistent calculations of the plasma equilibrium with the VMEC [2] and SPEC [3] codes have been performed for an up-down symmetric shot (142603) in DIII-D. In these codes, a self-consistent calculation of the plasma response due to the RMP coils is calculated. The VMEC code globally enforces the constraints of ideal MHD; consequently, a continuously nestedmore » family of flux surfaces is enforced throughout the plasma domain. This approach necessarily precludes the observation of islands or field-line chaos. The SPEC code relaxes the constraints of ideal MHD locally, and allows for islands and field line chaos at or near the rational surfaces. Equilibria with finite pressure gradients are approximated by a set of discrete "ideal-interfaces" at the most irrational flux surfaces and where the strongest pressure gradients are observed. Both the VMEC and SPEC calculations are initialized from EFIT reconstructions of the plasma that are consistent with the experimental pressure and current profiles. A 3D reconstruction using the STELLOPT code, which fits VMEC equilibria to experimental measurements, has also been performed. Comparisons between the equilibria generated by the 3D codes and between STELLOPT and EFIT are presented.« less

3D Equilibrium Effects Due to RMP Application on DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazerson, S.; Lazarus, E.; Hudson, S.

2012-06-20

The mitigation and suppression of edge localized modes (ELMs) through application of resonant magnetic perturbations (RMPs) in Tokamak plasmas is a well documented phenomenon. Vacuum calculations suggest the formation of edge islands and stochastic regions when RMPs are applied to the axisymmetric equilibria. Self-consistent calculations of the plasma equilibrium with the VMEC and SPEC codes have been performed for an up-down symmetric shot in DIII-D. In these codes, a self-consistent calculation of the plasma response due to the RMP coils is calculated. The VMEC code globally enforces the constraints of ideal MHD; consequently, a continuously nested family of flux surfacesmore » is enforced throughout the plasma domain. This approach necessarily precludes the observation of islands or field-line chaos. The SPEC code relaxes the constraints of ideal MHD locally, and allows for islands and field line chaos at or near the rational surfaces. Equilibria with finite pressure gradients are approximated by a set of discrete "ideal-interfaces" at the most irrational flux surfaces and where the strongest pressure gradients are observed. Both the VMEC and SPEC calculations are initialized from EFIT reconstructions of the plasma that are consistent with the experimental pressure and current profiles. A 3D reconstruction using the STELLOPT code, which fits VMEC equilibria to experimental measurements, has also been performed. Comparisons between the equilibria generated by the 3D codes and between STELLOPT and EFIT are presented.« less

Optimized Unlike-Pair Interactions for Water-Carbon Dioxide Mixtures described by the SPC/E and EPM2 Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlcek, Lukas; Chialvo, Ariel A; Cole, David

The unlike- pair interaction parameters for the SPC/E- EPM2 models have been optimized to reproduce the mutual solubility of water and carbon dioxide at the conditions of liquid- supercritical fluid phase equilibria. An efficient global optimization of the parameters is achieved through an implementation of the coupling parameter approach, adapted to phase equilibria calculations in the Gibbs ensemble, that explicitly corrects for the over- polarization of the SPC/E water molecule in the non- polar CO2 environments. The resulting H2O- CO2 force field reproduces accurately the available experimental solubilities at the two fluid phases in equilibria as well as the correspondingmore » species tracer diffusion coefficients.« less

Free energy and phase equilibria for the restricted primitive model of ionic fluids from Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Orkoulas, Gerassimos; Panagiotopoulos, Athanassios Z.

1994-07-01

In this work, we investigate the liquid-vapor phase transition of the restricted primitive model of ionic fluids. We show that at the low temperatures where the phase transition occurs, the system cannot be studied by conventional molecular simulation methods because convergence to equilibrium is slow. To accelerate convergence, we propose cluster Monte Carlo moves capable of moving more than one particle at a time. We then address the issue of charged particle transfers in grand canonical and Gibbs ensemble Monte Carlo simulations, for which we propose a biased particle insertion/destruction scheme capable of sampling short interparticle distances. We compute the chemical potential for the restricted primitive model as a function of temperature and density from grand canonical Monte Carlo simulations and the phase envelope from Gibbs Monte Carlo simulations. Our calculated phase coexistence curve is in agreement with recent results of Caillol obtained on the four-dimensional hypersphere and our own earlier Gibbs ensemble simulations with single-ion transfers, with the exception of the critical temperature, which is lower in the current calculations. Our best estimates for the critical parameters are T*c=0.053, ρ*c=0.025. We conclude with possible future applications of the biased techniques developed here for phase equilibrium calculations for ionic fluids.

Experimental tests of linear and nonlinear three-dimensional equilibrium models in DIII-D

DOE PAGES

King, Josh D.; Strait, Edward J.; Lazerson, Samuel A.; ...

2015-07-01

DIII-D experiments using new detailed magnetic diagnostics show that linear, ideal magnetohydrodynamics (MHD) theory quantitatively describes the magnetic structure (as measured externally) of three-dimensional (3D) equilibria resulting from applied fields with toroidal mode number n = 1, while a nonlinear solution to ideal MHD force balance, using the VMEC code, requires the inclusion of n ≥ 1 to achieve similar agreement. Moreover, these tests are carried out near ITER baseline parameters, providing a validated basis on which to exploit 3D fields for plasma control development. We determine scans of the applied poloidal spectrum and edge safety factors which confirm thatmore » low-pressure, n = 1 non-axisymmetric tokamak equilibria are a single, dominant, stable eigenmode. But, at higher beta, near the ideal kink mode stability limit in the absence of a conducting wall, the qualitative features of the 3D structure are observed to vary in a way that is not captured by ideal MHD.« less

Experimental Analysis of the Role of Fluid Transport Properties in Fluid-Induced Fracture Initiation and Propagation

NASA Astrophysics Data System (ADS)

Boutt, D.; McPherson, B. J.; Cook, B. K.; Goodwin, L. B.; Williams, J. R.; Lee, M. Y.; Patteson, R.

2003-12-01

It is well known that pore fluid pressure fundamentally influences a rock's mechanical response to stress. However, most measures of the mechanical behavior of rock (e.g. shear strength, Young's modulus) do not incorporate, either explicitly or implicitly, pore fluid pressure or transport properties of rock. Current empirical and theoretical criteria that define the amount of stress a given body of rock can support before fracturing also lack a direct connection between fluid transport and mechanical properties. Our research goal is to use laboratory experimental results to elucidate correlations between rock transport properties and fracture behavior under idealized loading conditions. In strongly coupled fluid-solid systems the evolution of the solid framework is influenced by the fluid and vice versa. These couplings often result in changes of the bulk material properties (i.e. permeability and failure strength) with respect to the fluid's ability to move through the solid and the solids ability to transmit momentum. Feedbacks between fluid and solid framework ultimately play key roles in understanding the spatial and temporal evolution of the coupled fluid-solid system. Discretely coupled models of fluid and solid mechanics were developed a priori to design an experimental approach for testing the role of fluid transport parameters in rock fracture. The experimental approach consists of first loading a fluid saturated cylindrical rock specimen under hydrostatic conditions and then applying a differential stress such that the maximum stress is perpendicular to the cylinder long axis. At the beginning of the test the minimum stress and the fluid pressure are dropped at the same time such that the resulting difference in the initial fluid pressure and the final fluid pressure is greater than the final minimum stress. These loading conditions should produce a fluid driven tensile fracture that is perpendicular to the cylinder long axis. Initial analyses using

Numerical investigation of fluid-particle interactions for embolic stroke

NASA Astrophysics Data System (ADS)

Mukherjee, Debanjan; Padilla, Jose; Shadden, Shawn C.

2016-04-01

Roughly one-third of all strokes are caused by an embolus traveling to a cerebral artery and blocking blood flow in the brain. The objective of this study is to gain a detailed understanding of the dynamics of embolic particles within arteries. Patient computed tomography image is used to construct a three-dimensional model of the carotid bifurcation. An idealized carotid bifurcation model of same vessel diameters was also constructed for comparison. Blood flow velocities and embolic particle trajectories are resolved using a coupled Euler-Lagrange approach. Blood is modeled as a Newtonian fluid, discretized using the finite volume method, with physiologically appropriate inflow and outflow boundary conditions. The embolus trajectory is modeled using Lagrangian particle equations accounting for embolus interaction with blood as well as vessel wall. Both one- and two-way fluid-particle coupling are considered, the latter being implemented using momentum sources augmented to the discretized flow equations. It was observed that for small-to-moderate particle sizes (relative to vessel diameters), the estimated particle distribution ratio—with and without the inclusion of two-way fluid-particle momentum exchange—were found to be similar. The maximum observed differences in distribution ratio with and without the coupling were found to be higher for the idealized bifurcation model. Additionally, the distribution was found to be reasonably matching the volumetric flow distribution for the idealized model, while a notable deviation from volumetric flow was observed in the anatomical model. It was also observed from an analysis of particle path lines that particle interaction with helical flow, characteristic of anatomical vasculature models, could play a prominent role in transport of embolic particle. The results indicate therefore that flow helicity could be an important hemodynamic indicator for analysis of embolus particle transport. Additionally, in the presence

Thermodynamic analysis of reaction equilibria in ionic and molecular liquid systems by high-temperature Raman spectroscopy.

PubMed

Kalampounias, Angelos G; Boghosian, Soghomon

2009-09-01

A formalism for correlating relative Raman band intensities with the stoichiometric coefficients, the equilibrium constant, and the thermodynamics of reaction equilibria in solution is derived. The proposed method is used for studying: (1) the thermal dissociation of molten KHSO(4) in the temperature range 240-450 degrees C; (2) the dinuclear complex formation in molten TaCl(5)-AlCl(3) mixtures at temperatures between 125 and 235 degrees C. The experimental and calculational procedures for exploiting the temperature-dependent Raman band intensities in the molten phase as well as (if applicable) in the vapors thereof are described and used for determining the enthalpy of the equilibria: (1) 2HSO(4)(-)(l) <--> S(2)O(7)(2-)(l) + H(2)O(g), DeltaH(0)=64.9 +/- 2.9 kJ mol(-1); and (2) 1/2Ta(2)Cl(10)(l) + 1/2Al(2)Cl(6)(l) <--> TaAlCl(8)(l), DeltaH(0)=-12.1 +/- 1.5 kJ mol(-1).

Analysis of the expected density of internal equilibria in random evolutionary multi-player multi-strategy games.

PubMed

Duong, Manh Hong; Han, The Anh

2016-12-01

In this paper, we study the distribution and behaviour of internal equilibria in a d-player n-strategy random evolutionary game where the game payoff matrix is generated from normal distributions. The study of this paper reveals and exploits interesting connections between evolutionary game theory and random polynomial theory. The main contributions of the paper are some qualitative and quantitative results on the expected density, [Formula: see text], and the expected number, E(n, d), of (stable) internal equilibria. Firstly, we show that in multi-player two-strategy games, they behave asymptotically as [Formula: see text] as d is sufficiently large. Secondly, we prove that they are monotone functions of d. We also make a conjecture for games with more than two strategies. Thirdly, we provide numerical simulations for our analytical results and to support the conjecture. As consequences of our analysis, some qualitative and quantitative results on the distribution of zeros of a random Bernstein polynomial are also obtained.

Kirkwood–Buff integrals for ideal solutions

PubMed Central

Ploetz, Elizabeth A.; Bentenitis, Nikolaos; Smith, Paul E.

2010-01-01

The Kirkwood–Buff (KB) theory of solutions is a rigorous theory of solution mixtures which relates the molecular distributions between the solution components to the thermodynamic properties of the mixture. Ideal solutions represent a useful reference for understanding the properties of real solutions. Here, we derive expressions for the KB integrals, the central components of KB theory, in ideal solutions of any number of components corresponding to the three main concentration scales. The results are illustrated by use of molecular dynamics simulations for two binary solutions mixtures, benzene with toluene, and methanethiol with dimethylsulfide, which closely approach ideal behavior, and a binary mixture of benzene and methanol which is nonideal. Simulations of a quaternary mixture containing benzene, toluene, methanethiol, and dimethylsulfide suggest this system displays ideal behavior and that ideal behavior is not limited to mixtures containing a small number of components. PMID:20441282

Design of snowflake-diverted equilibria of CFETR

NASA Astrophysics Data System (ADS)

Hang, LI; Xiang, GAO; Guoqiang, LI; Zhengping, LUO; Damao, YAO; Yong, GUO

2018-03-01

The Chinese Fusion Engineering Test Reactor (CFETR) represents the next generation of full superconducting fusion reactors in China. Recently, CFETR was redesigned with a larger size and will be operated in two phases. To reduce the heat flux on the target plate, a snowflake (SF) divertor configuration is proposed. In this paper we show that by adding two dedicated poloidal field (PF) coils, the SF configuration can be achieved in both phases. The equilibria were calculated by TEQ code for a range of self-inductances l i3. The coil currents were calculated at some fiducial points in the flattop phase. The results indicate that the PF coil system has the ability to maintain a long flattop phase in 7.5 and 10 MA inductive scenarios for the single null divertor (SND) and SF divertor configurations. The properties of the SF configuration were also analyzed. The connection length and flux expansion of the SF divertor were both increased significantly over the SND.

Fluid-induced Blueschist Preservation on Syros, Cyclades, Southern Greece

NASA Astrophysics Data System (ADS)

Kleine, B. I.; Huet, B.; Skelton, A. D. L.

2012-04-01

passing through the reaction front is buffered to higher X(CO2) by the reaction glaucophane+phengite+calcite+H2O=albite+chlorite+epidote+quartz+CO2. This fluid travels faster along paths of structural weakness (e.g. shear zones, faults). If this fluid reaches colder regions more rapidly such that the fluid chemistry is unable to "keep up" with the position of the reaction equilibria as the temperature falls, X(CO2) will be effectively shifted back into the blueschist stability field and blueschist will be preserved, specifically within high flux regions, such as shear zones and faults. [1] Matthews & Schliestedt (1984), Contributions to Mineralogy and Petrology, 88, 150-163. [2] Breeding et al. (2003), Geochemistry Geophysics Geosystems, 4, 1-11.

Galilei group with multiple central extension, vorticity, and entropy generation: Exotic fluid in 3 +1 dimensions

NASA Astrophysics Data System (ADS)

Das, Praloy; Ghosh, Subir

2017-12-01

A noncommutative extension of an ideal (Hamiltonian) fluid model in 3 +1 dimensions is proposed. The model enjoys several interesting features: it allows a multiparameter central extension in Galilean boost algebra (which is significant being contrary to the existing belief that a similar feature can appear only in 2 +1 -dimensions); noncommutativity generates vorticity in a canonically irrotational fluid; it induces a nonbarotropic pressure leading to a nonisentropic system. (Barotropic fluids are entropy preserving as the pressure depends only on the matter density.) Our fluid model is termed "exotic" since it has a close resemblance with the extensively studied planar (2 +1 dimensions) exotic models and exotic (noncommutative) field theories.

Ideal regularization for learning kernels from labels.

PubMed

Pan, Binbin; Lai, Jianhuang; Shen, Lixin

2014-08-01

In this paper, we propose a new form of regularization that is able to utilize the label information of a data set for learning kernels. The proposed regularization, referred to as ideal regularization, is a linear function of the kernel matrix to be learned. The ideal regularization allows us to develop efficient algorithms to exploit labels. Three applications of the ideal regularization are considered. Firstly, we use the ideal regularization to incorporate the labels into a standard kernel, making the resulting kernel more appropriate for learning tasks. Next, we employ the ideal regularization to learn a data-dependent kernel matrix from an initial kernel matrix (which contains prior similarity information, geometric structures, and labels of the data). Finally, we incorporate the ideal regularization to some state-of-the-art kernel learning problems. With this regularization, these learning problems can be formulated as simpler ones which permit more efficient solvers. Empirical results show that the ideal regularization exploits the labels effectively and efficiently. Copyright © 2014 Elsevier Ltd. All rights reserved.

Intuitionistic fuzzy n-fold KU-ideal of KU-algebra

NASA Astrophysics Data System (ADS)

Mostafa, Samy M.; Kareem, Fatema F.

2018-05-01

In this paper, we apply the notion of intuitionistic fuzzy n-fold KU-ideal of KU-algebra. Some types of ideals such as intuitionistic fuzzy KU-ideal, intuitionistic fuzzy closed ideal and intuitionistic fuzzy n-fold KU-ideal are studied. Also, the relations between intuitionistic fuzzy n-fold KU-ideal and intuitionistic fuzzy KU-ideal are discussed. Furthermore, a few results of intuitionistic fuzzy n-fold KU-ideals of a KU-algebra under homomorphism are discussed.

Role of a continuous MHD dynamo in the formation of 3D equilibria in fusion plasmas

NASA Astrophysics Data System (ADS)

Piovesan, P.; Bonfiglio, D.; Cianciosa, M.; Luce, T. C.; Taylor, N. Z.; Terranova, D.; Turco, F.; Wilcox, R. S.; Wingen, A.; Cappello, S.; Chrystal, C.; Escande, D. F.; Holcomb, C. T.; Marrelli, L.; Paz-Soldan, C.; Piron, L.; Predebon, I.; Zaniol, B.; DIII-D, The; RFX-Mod Teams

2017-07-01

Stationary 3D equilibria can form in fusion plasmas via saturation of magnetohydrodynamic (MHD) instabilities or stimulated by external 3D fields. In these cases the current profile is anomalously broad due to magnetic flux pumping produced by the MHD modes. Flux pumping plays an important role in hybrid tokamak plasmas, maintaining the minimum safety factor above unity and thus removing sawteeth. It also enables steady-state hybrid operation, by redistributing non-inductive current driven near the center by electron cyclotron waves. A validated flux pumping model is not yet available, but it would be necessary to extrapolate hybrid operation to future devices. In this work flux pumping physics is investigated for helical core equilibria stimulated by external 3D fields in DIII-D hybrid plasmas. We show that flux pumping can be produced in a continuous way by an MHD dynamo emf. The same effect maintains helical equilibria in reversed-field pinch (RFP) plasmas. The effective MHD dynamo loop voltage is calculated for experimental 3D equilibrium reconstructions, by balancing Ohm’s law over helical flux surfaces, and is consistent with the expected current redistribution. Similar results are also obtained with more sophisticated nonlinear MHD simulations. The same modelling approach is applied to helical RFP states forming spontaneously in RFX-mod as the plasma current is raised above 0.8-1 MA. This comparison allows to identify the underlying physics common to tokamak and RFP: a helical core displacement modulates parallel current density along flux tubes, which requires a helical electrostatic potential to build up, giving rise to a helical MHD dynamo flow.

Role of a continuous MHD dynamo in the formation of 3D equilibria in fusion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piovesan, P.; Bonfiglio, D.; Cianciosa, M.

Stationary 3D equilibria can form in fusion plasmas via saturation of magnetohydrodynamic (MHD) instabilities or stimulated by external 3D fields. In these cases the current profile is anomalously broad due to magnetic flux pumping produced by the MHD modes. Flux pumping plays an important role in hybrid tokamak plasmas, maintaining the minimum safety factor above unity and thus removing sawteeth. It also enables steady-state hybrid operation, by redistributing non-inductive current driven near the center by electron cyclotron waves. A validated flux pumping model is not yet available, but it would be necessary to extrapolate hybrid operation to future devices. Inmore » this work flux pumping physics is investigated for helical core equilibria stimulated by external 3D fields in DIII-D hybrid plasmas. We show that flux pumping can be produced in a continuous way by an MHD dynamo emf. The same effect maintains helical equilibria in reversed-field pinch (RFP) plasmas. The effective MHD dynamo loop voltage is calculated for experimental 3D equilibrium reconstructions, by balancing Ohm’s law over helical flux surfaces, and is consistent with the expected current redistribution. Similar results are also obtained with more sophisticated nonlinear MHD simulations. The same modelling approach is applied to helical RFP states forming spontaneously in RFX-mod as the plasma current is raised above 0.8–1 MA. This comparison allows to identify the underlying physics common to tokamak and RFP: a helical core displacement modulates parallel current density along flux tubes, which requires a helical electrostatic potential to build up, giving rise to a helical MHD dynamo flow.« less

Role of a continuous MHD dynamo in the formation of 3D equilibria in fusion plasmas

DOE PAGES

Piovesan, P.; Bonfiglio, D.; Cianciosa, M.; ...

2017-04-28

Stationary 3D equilibria can form in fusion plasmas via saturation of magnetohydrodynamic (MHD) instabilities or stimulated by external 3D fields. In these cases the current profile is anomalously broad due to magnetic flux pumping produced by the MHD modes. Flux pumping plays an important role in hybrid tokamak plasmas, maintaining the minimum safety factor above unity and thus removing sawteeth. It also enables steady-state hybrid operation, by redistributing non-inductive current driven near the center by electron cyclotron waves. A validated flux pumping model is not yet available, but it would be necessary to extrapolate hybrid operation to future devices. Inmore » this work flux pumping physics is investigated for helical core equilibria stimulated by external 3D fields in DIII-D hybrid plasmas. We show that flux pumping can be produced in a continuous way by an MHD dynamo emf. The same effect maintains helical equilibria in reversed-field pinch (RFP) plasmas. The effective MHD dynamo loop voltage is calculated for experimental 3D equilibrium reconstructions, by balancing Ohm’s law over helical flux surfaces, and is consistent with the expected current redistribution. Similar results are also obtained with more sophisticated nonlinear MHD simulations. The same modelling approach is applied to helical RFP states forming spontaneously in RFX-mod as the plasma current is raised above 0.8–1 MA. This comparison allows to identify the underlying physics common to tokamak and RFP: a helical core displacement modulates parallel current density along flux tubes, which requires a helical electrostatic potential to build up, giving rise to a helical MHD dynamo flow.« less

Examples for Non-Ideal Solution Thermodynamics Study

ERIC Educational Resources Information Center

David, Carl W.

2004-01-01

A mathematical model of a non-ideal solution is presented, where it is shown how and where the non-ideality manifests itself in the standard thermodynamics tableau. Examples related to the non-ideal solution thermodynamics study are also included.

Ideal Magnetic Dipole Scattering

NASA Astrophysics Data System (ADS)

Feng, Tianhua; Xu, Yi; Zhang, Wei; Miroshnichenko, Andrey E.

2017-04-01

We introduce the concept of tunable ideal magnetic dipole scattering, where a nonmagnetic nanoparticle scatters light as a pure magnetic dipole. High refractive index subwavelength nanoparticles usually support both electric and magnetic dipole responses. Thus, to achieve ideal magnetic dipole scattering one has to suppress the electric dipole response. Such a possibility was recently demonstrated for the so-called anapole mode, which is associated with zero electric dipole scattering. By spectrally overlapping the magnetic dipole resonance with the anapole mode, we achieve ideal magnetic dipole scattering in the far field with tunable strong scattering resonances in the near infrared spectrum. We demonstrate that such a condition can be realized at least for two subwavelength geometries. One of them is a core-shell nanosphere consisting of a Au core and silicon shell. It can be also achieved in other geometries, including nanodisks, which are compatible with current nanofabrication technology.

Navigable networks as Nash equilibria of navigation games.

PubMed

Gulyás, András; Bíró, József J; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

2015-07-03

Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network.

IDEAL 3D spoiled gradient echo of the articular cartilage of the knee on 3.0 T MRI: a comparison with conventional 3.0 T fast spin-echo T2 fat saturation image.

PubMed

Han, Chul Hee; Park, Hee Jin; Lee, So Yeon; Chung, Eun Chul; Choi, Seon Hyeong; Yun, Ji Sup; Rho, Myung Ho

2015-12-01

Many two-dimensional (2D) morphologic cartilage imaging sequences have disadvantages such as long acquisition time, inadequate spatial resolution, suboptimal tissue contrast, and image degradation secondary to artifacts. IDEAL imaging can overcome these disadvantages. To compare sound-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and quality of two different methods of imaging that include IDEAL 3D SPGR and 3.0-T FSE T2 fat saturation (FS) imaging and to evaluate the utility of IDEAL 3D SPGR for knee joint imaging. SNR and CNR of the patellar and femoral cartilages were measured and calculated. Two radiologists performed subjective scoring of all images for three measures: general image quality, FS, and cartilage evaluation. SNR and CNR values were compared by paired Student's t-tests. Mean SNRs of patellar and femoral cartilages were 90% and 66% higher, respectively, for IDEAL 3D SPGR. CNRs of patellar cartilages and joint fluids were 2.4 times higher for FSE T2 FS, and CNR between the femoral cartilage and joint fluid was 2.2 times higher for FSE T2 FS. General image quality and FS were superior using FSE T2 FS compared to those of IDEAL 3D SPGR imaging according to both readers, while cartilage evaluation was superior using IDEAL 3D SPGR. Additionally, cartilage injuries were more prominent in IDEAL 3D SPGR than in FSE T2FS according to both readers. IDEAL 3D SPGR images show excellent visualization of patellar and femoral cartilages in 3.0 T and can compensate for the weaknesses of FSE T2 FS in the evaluation of cartilage injuries. © The Foundation Acta Radiologica 2014.

Tautomeric equilibria in solutions of 1-methyl-2-phenacylbenzimidazoles

NASA Astrophysics Data System (ADS)

Skotnicka, Agnieszka; Czeleń, Przemysław; Gawinecki, Ryszard

2017-04-01

Until now the susceptibility of 1-methyl-2-phenacylbenzimidazoles to the proton transfer has not been carefully examined. There only have been selective trials to recognize tautomeric equilibrium of substituted compounds. Unfortunately, conclusions of these studies are often conflicting. Therefore, the aim of this work was to analyze the influence of the factors affecting the tautomeric processes of substituted 1-methyl-2-phenacylbenzimidazoles in solutions of chloroform by spectroscopic technique of 1H and 13C NMR. Complex equilibria may only take place when molecules of tautomeric species contain multiple basic and/or acidic centres. Analysis of NMR spectra show unequivocally that 1-methyl-2-phenacylbenzimidazoles (ketimine tautomeric form) are in equilibrium with (Z)-2-(1-methyl-1H-benzo[d]imidazol-2yl)-1-phenylethenols (enolimine).

An Idealized, Single Radial Swirler, Lean-Direct-Injection (LDI) Concept Meshing Script

NASA Technical Reports Server (NTRS)

Iannetti, Anthony C.; Thompson, Daniel

2008-01-01

To easily study combustor design parameters using computational fluid dynamics codes (CFD), a Gridgen Glyph-based macro (based on the Tcl scripting language) dubbed BladeMaker has been developed for the meshing of an idealized, single radial swirler, lean-direct-injection (LDI) combustor. BladeMaker is capable of taking in a number of parameters, such as blade width, blade tilt with respect to the perpendicular, swirler cup radius, and grid densities, and producing a three-dimensional meshed radial swirler with a can-annular (canned) combustor. This complex script produces a data format suitable for but not specific to the National Combustion Code (NCC), a state-of-the-art CFD code developed for reacting flow processes.

Ideal Gas with a Varying (Negative Absolute) Temperature: an Alternative to Dark Energy?

NASA Astrophysics Data System (ADS)

Saha, Subhajit; Mondal, Anindita; Corda, Christian

2018-02-01

The present work is an attempt to investigate whether the evolutionary history of the Universe from the offset of inflation can be described by assuming the cosmic fluid to be an ideal gas with a specific gas constant but a varying negative absolute temperature (NAT). The motivation of this work is to search for an alternative to the "exotic" and "supernatural" dark energy (DE). In fact, the NAT works as an "effective quintessence" and there is need to deal neither with exotic matter like DE nor with modified gravity theories. For the sake of completeness, we release some clarifications on NATs in Section 3 of the paper.

Using a Differential Scanning Calorimeter to Teach Phase Equilibria to Students of Igneous and Metamorphic Petrology

ERIC Educational Resources Information Center

Maria, Anton H.; Millam, Evan L.; Wright, Carrie L.

2011-01-01

As an aid for teaching phase equilibria to undergraduate students of igneous and metamorphic petrology, we have designed a laboratory exercise that allows them to create a phase diagram from data produced by differential scanning calorimetry. By preparing and analyzing samples of naphthalene and phenanthrene, students acquire hands-on insight into…

Using melt inclusions and fluid inclusions to track ore-metal behavior in magma-hydrothermal systems (Invited)

NASA Astrophysics Data System (ADS)

Lowenstern, J. B.; Audétat, A.

2013-12-01

Melt and fluid inclusions yield important clues to the history of igneous melts and their related hydrothermal ore deposits (1). Under ideal conditions, melt inclusions in volcanic rocks yield data on the actual concentrations of ore metals and volatiles during instantaneous snapshots of crystallization and degassing. Their varying compositions can directly reflect sequestration of ore-metals in fractionating minerals and/or exsolving brines and vapors. Frequently, scientists compare the concentration of volatile elements in melt inclusions with their abundance in devolatilized matrix glass. Though this provides an informative qualitative overview of volatility, it is essentially impossible to use such data to calculate thermodynamically relevant partition coefficients. The resulting partitioning ratio instead represents fractionation over a wide range of pressures, and compositions (for both exsolved fluid and silicate melt). Ideally, workers should identify co-entrapped fluid and glass inclusions to provide more thermodynamically meaningful partitioning ratios for volatile metals and gases (2,3). Unfortunately, the occurrence of fluid inclusions co-entrapped with silicate melt is relatively rare, and studies of synthetic fluid and melt inclusions may be the most practical means of exploring the effect of crystallization and degassing in 'natural' systems. As with melt inclusions, under ideal conditions, fluid inclusions in intrusive rocks represent the compositions of fluids generated within associated magmatic-hydrothermal fluid systems. Multiple generations of cross-cutting fractures may be generated, resulting in trails of secondary and pseudosecondary inclusions in igneous minerals, and primary and secondary inclusions in hydrothermal assemblages. Chemistry of the fluids preserved within different inclusion generations will change markedly due to changes in magmatic temperature and pressure and mixing of diverse external fluids from meteoric and metamorphic

Toward the accurate first-principles prediction of ionization equilibria in proteins.

PubMed

Khandogin, Jana; Brooks, Charles L

2006-08-08

The calculation of pK(a) values for ionizable sites in proteins has been traditionally based on numerical solutions of the Poisson-Boltzmann equation carried out using a high-resolution protein structure. In this paper, we present a method based on continuous constant pH molecular dynamics (CPHMD) simulations, which allows the first-principles description of protein ionization equilibria. Our method utilizes an improved generalized Born implicit solvent model with an approximate Debye-Hückel screening function to account for salt effects and the replica-exchange (REX) protocol for enhanced conformational and protonation state sampling. The accuracy and robustness of the present method are demonstrated by 1 ns REX-CPHMD titration simulations of 10 proteins, which exhibit anomalously large pK(a) shifts for the carboxylate and histidine side chains. The experimental pK(a) values of these proteins are reliably reproduced with a root-mean-square error ranging from 0.6 unit for proteins containing few buried ionizable side chains to 1.0 unit or slightly higher for proteins containing ionizable side chains deeply buried in the core and experiencing strong charge-charge interactions. This unprecedented level of agreement with experimental benchmarks for the de novo calculation of pK(a) values suggests that the CPHMD method is maturing into a practical tool for the quantitative prediction of protein ionization equilibria, and this, in turn, opens a door to atomistic simulations of a wide variety of pH-coupled conformational phenomena in biological macromolecules such as protein folding or misfolding, aggregation, ligand binding, membrane interaction, and catalysis.

Equilibria, information and frustration in heterogeneous network games with conflicting preferences

NASA Astrophysics Data System (ADS)

Mazzoli, M.; Sánchez, A.

2017-11-01

Interactions between people are the basis on which the structure of our society arises as a complex system and, at the same time, are the starting point of any physical description of it. In the last few years, much theoretical research has addressed this issue by combining the physics of complex networks with a description of interactions in terms of evolutionary game theory. We here take this research a step further by introducing a most salient societal factor such as the individuals’ preferences, a characteristic that is key to understanding much of the social phenomenology these days. We consider a heterogeneous, agent-based model in which agents interact strategically with their neighbors, but their preferences and payoffs for the possible actions differ. We study how such a heterogeneous network behaves under evolutionary dynamics and different strategic interactions, namely coordination games and best shot games. With this model we study the emergence of the equilibria predicted analytically in random graphs under best response dynamics, and we extend this test to unexplored contexts like proportional imitation and scale free networks. We show that some theoretically predicted equilibria do not arise in simulations with incomplete information, and we demonstrate the importance of the graph topology and the payoff function parameters for some games. Finally, we discuss our results with the available experimental evidence on coordination games, showing that our model agrees better with the experiment than standard economic theories, and draw hints as to how to maximize social efficiency in situations of conflicting preferences.

The latent heat of vaporization of supercritical fluids

NASA Astrophysics Data System (ADS)

Banuti, Daniel; Raju, Muralikrishna; Hickey, Jean-Pierre; Ihme, Matthias

2016-11-01

The enthalpy of vaporization is the energy required to overcome intermolecular attractive forces and to expand the fluid volume against the ambient pressure when transforming a liquid into a gas. It diminishes for rising pressure until it vanishes at the critical point. Counterintuitively, we show that a latent heat is in fact also required to heat a supercritical fluid from a liquid to a gaseous state. Unlike its subcritical counterpart, the supercritical pseudoboiling transition is spread over a finite temperature range. Thus, in addition to overcoming intermolecular attractive forces, added energy simultaneously heats the fluid. Then, considering a transition from a liquid to an ideal gas state, we demonstrate that the required enthalpy is invariant to changes in pressure for 0 < p < 3pcr . This means that the classical pressure-dependent latent heat is merely the equilibrium part of the phase transition. The reduction at higher pressures is compensated by an increase in a nonequilibrium latent heat required to overcome residual intermolecular forces in the real fluid vapor during heating. At supercritical pressures, all of the transition occurs at non-equilibrium; for p -> 0 , all of the transition occurs at equilibrium.

Prediction of vapour-liquid and vapour-liquid-liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators

NASA Astrophysics Data System (ADS)

Narayanan, Vineed; Venkatarathnam, G.

2018-03-01

Nitrogen-hydrocarbon mixtures are widely used as refrigerants in J-T refrigerators operating with mixtures, as well as in natural gas liquefiers. The Peng-Robinson equation of state has traditionally been used to simulate the above cryogenic process. Multi parameter Helmholtz energy equations are now preferred for determining the properties of natural gas. They have, however, been used only to predict vapour-liquid equilibria, and not vapour-liquid-liquid equilibria that can occur in mixtures used in cryogenic mixed refrigerant processes. In this paper the vapour-liquid equilibrium of binary mixtures of nitrogen-methane, nitrogen-ethane, nitrogen-propane, nitrogen-isobutane and three component mixtures of nitrogen-methane-ethane and nitrogen-methane-propane have been studied with the Peng-Robinson and the Helmholtz energy equations of state of NIST REFPROP and compared with experimental data available in the literature.

Effect of Prestresses on the Dispersion of Quasi-Lamb Waves in the System Consisting of an Ideal Liquid Layer and a Compressible Elastic Layer

NASA Astrophysics Data System (ADS)

Bagno, A. M.

2017-03-01

The propagation of quasi-Lamb waves in a prestrained compressible elastic layer interacting with a layer of an ideal compressible fluid is studied. The three-dimensional equations of linearized elasticity and the assumption of finite strains for the elastic layer and the three-dimensional linearized Euler equations for the fluid are used. The dispersion curves for the quasi-Lamb modes are plotted over a wide frequency range. The effect of prestresses and the thickness of the elastic and liquid layers on the frequency spectrum of normal quasi-Lamb waves is analyzed. The localization properties of the lower quasi-Lamb modes in the elastic-fluid waveguides are studied. The numerical results are presented in the form of graphs and analyzed

Improved Classification of Mammograms Following Idealized Training

PubMed Central

Hornsby, Adam N.; Love, Bradley C.

2014-01-01

People often make decisions by stochastically retrieving a small set of relevant memories. This limited retrieval implies that human performance can be improved by training on idealized category distributions (Giguère & Love, 2013). Here, we evaluate whether the benefits of idealized training extend to categorization of real-world stimuli, namely classifying mammograms as normal or tumorous. Participants in the idealized condition were trained exclusively on items that, according to a norming study, were relatively unambiguous. Participants in the actual condition were trained on a representative range of items. Despite being exclusively trained on easy items, idealized-condition participants were more accurate than those in the actual condition when tested on a range of item types. However, idealized participants experienced difficulties when test items were very dissimilar from training cases. The benefits of idealization, attributable to reducing noise arising from cognitive limitations in memory retrieval, suggest ways to improve real-world decision making. PMID:24955325

Improved Classification of Mammograms Following Idealized Training.

PubMed

Hornsby, Adam N; Love, Bradley C

2014-06-01

People often make decisions by stochastically retrieving a small set of relevant memories. This limited retrieval implies that human performance can be improved by training on idealized category distributions (Giguère & Love, 2013). Here, we evaluate whether the benefits of idealized training extend to categorization of real-world stimuli, namely classifying mammograms as normal or tumorous. Participants in the idealized condition were trained exclusively on items that, according to a norming study, were relatively unambiguous. Participants in the actual condition were trained on a representative range of items. Despite being exclusively trained on easy items, idealized-condition participants were more accurate than those in the actual condition when tested on a range of item types. However, idealized participants experienced difficulties when test items were very dissimilar from training cases. The benefits of idealization, attributable to reducing noise arising from cognitive limitations in memory retrieval, suggest ways to improve real-world decision making.

The Direct Effect of Flexible Walls on Fontan Connection Fluid Dynamics

NASA Astrophysics Data System (ADS)

Tree, Mike; Fagan, Kiley; Yoganathan, Ajit

2014-11-01

The current standard treatment for sufferers of congenital heart defects is the palliative Fontan procedure. The Fontan procedure results in an anastomosis of major veins directly to the branched pulmonary arteries bypassing the dysfunctional ventricle. This total cavopulmonary connection (TCPC) extends life past birth, but Fontan patients still suffer long-term complications like decreased exercise capacity, protein-losing enteropathy, and pulmonary arteriovenous malformations (PAVM). These complications have direct ties to fluid dynamics within the connection. Previous experimental and computation studies of Fontan connection fluid dynamics employed rigid vessel models. More recent studies utilize flexible models, but a direct comparison of the fundamental fluid dynamics between rigid and flexible vessels only exists for a computational model, without a direct experimental validation. Thus, this study was a direct comparison of fluid dynamics within a rigid and two compliant idealized TCPCs. 2D particle image velocimetry measurements were collected at the connection center plane. Results include power loss, hepatic flow distribution, fluid shear stress, and flow structure recognition. The effect of flexible walls on these values and clinical impact will be discussed.

An ideal free-kick

NASA Astrophysics Data System (ADS)

De Luca, R.; Faella, O.

2017-01-01

The kinematics of a free-kick is studied. As in projectile motion, the free-kick is ideal since we assume that a point-like ball moves in the absence of air resistance. We have experienced the fortunate conjuncture of a classical mechanics lecture taught right before an important football game. These types of sports events might trigger a great deal of attention from the classroom. The idealized problem is devised in such a way that students are eager to come to the end of the whole story.

Conservative regularization of compressible dissipationless two-fluid plasmas

NASA Astrophysics Data System (ADS)

Krishnaswami, Govind S.; Sachdev, Sonakshi; Thyagaraja, A.

2018-02-01

This paper extends our earlier approach [cf. A. Thyaharaja, Phys. Plasmas 17, 032503 (2010) and Krishnaswami et al., Phys. Plasmas 23, 022308 (2016)] to obtaining à priori bounds on enstrophy in neutral fluids and ideal magnetohydrodynamics. This results in a far-reaching local, three-dimensional, non-linear, dispersive generalization of a KdV-type regularization to compressible/incompressible dissipationless 2-fluid plasmas and models derived therefrom (quasi-neutral, Hall, and ideal MHD). It involves the introduction of vortical and magnetic "twirl" terms λl 2 ( w l + ( q l / m l ) B ) × ( ∇ × w l ) in the ion/electron velocity equations ( l = i , e ) where w l are vorticities. The cut-off lengths λl and number densities nl must satisfy λl 2 n l = C l , where Cl are constants. A novel feature is that the "flow" current ∑ l q l n l v l in Ampère's law is augmented by a solenoidal "twirl" current ∑ l ∇ × ∇ × λl 2 j flow , l . The resulting equations imply conserved linear and angular momenta and a positive definite swirl energy density E * which includes an enstrophic contribution ∑ l ( 1 / 2 ) λl 2 ρ l wl 2 . It is shown that the equations admit a Hamiltonian-Poisson bracket formulation. Furthermore, singularities in ∇ × B are conservatively regularized by adding ( λB 2 / 2 μ 0 ) ( ∇ × B ) 2 to E * . Finally, it is proved that among regularizations that admit a Hamiltonian formulation and preserve the continuity equations along with the symmetries of the ideal model, the twirl term is unique and minimal in non-linearity and space derivatives of velocities.

On controlling nonlinear dissipation in high order filter methods for ideal and non-ideal MHD

NASA Technical Reports Server (NTRS)

Yee, H. C.; Sjogreen, B.

2004-01-01

The newly developed adaptive numerical dissipation control in spatially high order filter schemes for the compressible Euler and Navier-Stokes equations has been recently extended to the ideal and non-ideal magnetohydrodynamics (MHD) equations. These filter schemes are applicable to complex unsteady MHD high-speed shock/shear/turbulence problems. They also provide a natural and efficient way for the minimization of Div(B) numerical error. The adaptive numerical dissipation mechanism consists of automatic detection of different flow features as distinct sensors to signal the appropriate type and amount of numerical dissipation/filter where needed and leave the rest of the region free from numerical dissipation contamination. The numerical dissipation considered consists of high order linear dissipation for the suppression of high frequency oscillation and the nonlinear dissipative portion of high-resolution shock-capturing methods for discontinuity capturing. The applicable nonlinear dissipative portion of high-resolution shock-capturing methods is very general. The objective of this paper is to investigate the performance of three commonly used types of nonlinear numerical dissipation for both the ideal and non-ideal MHD.

Sulfate brines in fluid inclusions of hydrothermal veins: Compositional determinations in the system H2O-Na-Ca-Cl-SO4

NASA Astrophysics Data System (ADS)

Walter, Benjamin F.; Steele-MacInnis, Matthew; Markl, Gregor

2017-07-01

Sulfate is among the most abundant ions in seawater and sulfate-bearing brines are common in sedimentary basins, among other environments. However, the properties of sulfate-bearing fluid inclusions during microthermometry are as yet poorly constrained, restricting the interpretation of fluid-inclusion compositions where sulfate is a major ion. The Schwarzwald mining district on the eastern shoulder of the Upper Rhinegraben rift is an example of a geologic system characterized by sulfate-bearing brines, and constraints on the anion abundances (chloride versus sulfate) would be desirable as a potential means to differentiate fluid sources in hydrothermal veins in these regions. Here, we use the Pitzer-type formalism to calculate equilibrium conditions along the vapor-saturated liquidus of the system H2O-Na-Ca-Cl-SO4, and construct phase diagrams displaying the predicted phase equilibria. We combine these predicted phase relations with microthermometric and crush-leach analyses of fluid inclusions from veins in the Schwarzwald and Upper Rhinegraben, to estimate the compositions of these brines in terms of bulk salinity as well as cation and anion loads (sodium versus calcium, and chloride versus sulfate). These data indicate systematic differences in fluid compositions recorded by fluid inclusions, and demonstrate the application of detailed low-temperature microthermometry to determine compositions of sulfate-bearing brines. Thus, these data provide new constraints on fluid sources and paleo-hydrology of these classic basin-hosted ore-forming systems. Moreover, the phase diagrams presented herein can be applied directly to compositional determinations in other systems.

Recharging Our Sense of Idealism: Concluding Thoughts

ERIC Educational Resources Information Center

D'Andrea, Michael; Dollarhide, Colette T.

2011-01-01

In this article, the authors aim to recharge one's sense of idealism. They argue that idealism is the Vitamin C that sustains one's commitment to implementing humanistic principles and social justice practices in the work of counselors and educators. The idealism that characterizes counselors and educators who are humanistic and social justice…

Navigable networks as Nash equilibria of navigation games

PubMed Central

Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

2015-01-01

Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network. PMID:26138277

The Hall-induced stability of gravitating fluids

NASA Astrophysics Data System (ADS)

Karmakar, P. K.; Goutam, H. P.

2018-05-01

We analyze the stability behavior of low-density partially ionized self-gravitating magnetized unbounded dusty plasma fluid in the presence of the Hall diffusion effects (HDEs) in the non-ideal magnetohydrodynamic (MHD) equilibrium framework. The effects of inhomogeneous self-gravity are methodically included in the basic model tapestry. Application of the Fourier plane-wave perturbative treatment decouples the structuration representative parameters into a linear generalized dispersion relation (sextic) in a judicious mean-fluid approximation. The dispersion analysis shows that the normal mode, termed as the gravito-magneto-acoustic (GMA) mode, is drastically modified due to the HDEs. This mode is highly dispersive, and driven unstable by the Hall current resulting from the symmetry-breaking of electrons and ions relative to the magnetic field. The mode feature, which is derived from a modified induction with the positive Hall, is against the ideal MHD. It is further demonstrated that the HDEs play stabilizing roles by supporting the cloud against gravitational collapse. Provided that the HDEs are concurrently switched off, the collapse occurs on the global spatial scale due to enhanced inward accretion of the gravitating dust constituents. It is seen explicitly that the enhanced dust-charge leads to stabilizing effects. Besides, the Hall-induced fluctuations, as propagatory wave modes, exhibit both normal and anomalous dispersions. The reliability checkup of the entailed results as diverse corollaries and special cases are illustratively discussed in the panoptic light of the earlier paradigmatic predictions available in the literature.

Phase equilibria and thermodynamic modeling of ethane and propane hydrates in porous silica gels.

PubMed

Seo, Yongwon; Lee, Seungmin; Cha, Inuk; Lee, Ju Dong; Lee, Huen

2009-04-23

In the present study, we examined the active role of porous silica gels when used as natural gas storage and transportation media. We adopted the dispersed water in silica gel pores to substantially enhance active surface for contacting and encaging gas molecules. We measured the three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria of C(2)H(6) and C(3)H(8) hydrates in 6.0, 15.0, 30.0, and 100.0 nm silica gel pores to investigate the effect of geometrical constraints on gas hydrate phase equilibria. At specified temperatures, the hydrate stability region is shifted to a higher pressure region depending on pore size when compared with those of bulk hydrates. Through application of the Gibbs-Thomson relationship to the experimental data, we determined the values for the C(2)H(6) hydrate-water and C(3)H(8) hydrate-water interfacial tensions to be 39 +/- 2 and 45 +/- 1 mJ/m(2), respectively. By using these values, the calculation values were in good agreement with the experimental ones. The overall results given in this study could also be quite useful in various fields, such as exploitation of natural gas hydrate in marine sediments and sequestration of carbon dioxide into the deep ocean.

Applications of ionic liquids in biphasic separation: Aqueous biphasic systems and liquid-liquid equilibria.

PubMed

Shukla, Shashi Kant; Pandey, Shubha; Pandey, Siddharth

2018-07-20

Ionic liquids (ILs) have been receiving much attention in many fields of analytical chemistry because of their various interesting properties which distinguish them from volatile organic compounds. They offer both directional and non-directional forces towards a solute molecule and therefore act as excellent solvents for a wide range of polar and non-polar compounds. Because of the presence of various possible interactions, ILs easily undergo biphasic separation with water and other less polar/non-polar organic solvents. Their ability to create biphasic splitting makes them a promising candidate for liquid-liquid separation processes, such as aqueous biphasic systems and liquid-liquid equilibria. Various aspects of ILs in these separation methods are discussed in view of the origin of physical forces responsible for the biphasic interactions, the effect of structural components, temperature, pressure, pH and additives. The specific advantages of using ILs in aqueous biphasic systems and liquid-liquid equilibria in binary and ternary systems are discussed with a view to defining their future role in separation processes by giving major emphasis on developing non-toxic ILs with physical and solution properties tailored to the needs of specific sample preparation techniques. Copyright © 2017 Elsevier B.V. All rights reserved.

Convection in an ideal gas at high Rayleigh numbers.

PubMed

Tilgner, A

2011-08-01

Numerical simulations of convection in a layer filled with ideal gas are presented. The control parameters are chosen such that there is a significant variation of density of the gas in going from the bottom to the top of the layer. The relations between the Rayleigh, Peclet, and Nusselt numbers depend on the density stratification. It is proposed to use a data reduction which accounts for the variable density by introducing into the scaling laws an effective density. The relevant density is the geometric mean of the maximum and minimum densities in the layer. A good fit to the data is then obtained with power laws with the same exponent as for fluids in the Boussinesq limit. Two relations connect the top and bottom boundary layers: The kinetic energy densities computed from free fall velocities are equal at the top and bottom, and the products of free fall velocities and maximum horizontal velocities are equal for both boundaries.

Genetic and environmental influences on thin-ideal internalization.

PubMed

Suisman, Jessica L; O'Connor, Shannon M; Sperry, Steffanie; Thompson, J Kevin; Keel, Pamela K; Burt, S Alexandra; Neale, Michael; Boker, Steven; Sisk, Cheryl; Klump, Kelly L

2012-12-01

Current research on the etiology of thin-ideal internalization focuses on psychosocial influences (e.g., media exposure). The possibility that genetic influences also account for variance in thin-ideal internalization has never been directly examined. This study used a twin design to estimate genetic effects on thin-ideal internalization and examine if environmental influences are primarily shared or nonshared in origin. Participants were 343 postpubertal female twins (ages: 12-22 years; M = 17.61) from the Michigan State University Twin Registry. Thin-ideal internalization was assessed using the Sociocultural Attitudes toward Appearance Questionnaire-3. Twin modeling suggested significant additive genetic and nonshared environmental influences on thin-ideal internalization. Shared environmental influences were small and non-significant. Although prior research focused on psychosocial factors, genetic influences on thin-ideal internalization were significant and moderate in magnitude. Research is needed to investigate possible interplay between genetic and nonshared environmental factors in the development of thin-ideal internalization. Copyright © 2012 Wiley Periodicals, Inc.

Unifying dynamical and structural stability of equilibria

NASA Astrophysics Data System (ADS)

Arnoldi, Jean-François; Haegeman, Bart

2016-09-01

We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.

Unifying dynamical and structural stability of equilibria.

PubMed

Arnoldi, Jean-François; Haegeman, Bart

2016-09-01

We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.

A weak-coupling immersed boundary method for fluid-structure interaction with low density ratio of solid to fluid

NASA Astrophysics Data System (ADS)

Kim, Woojin; Lee, Injae; Choi, Haecheon

2018-04-01

We present a weak-coupling approach for fluid-structure interaction with low density ratio (ρ) of solid to fluid. For accurate and stable solutions, we introduce predictors, an explicit two-step method and the implicit Euler method, to obtain provisional velocity and position of fluid-structure interface at each time step, respectively. The incompressible Navier-Stokes equations, together with these provisional velocity and position at the fluid-structure interface, are solved in an Eulerian coordinate using an immersed-boundary finite-volume method on a staggered mesh. The dynamic equation of an elastic solid-body motion, together with the hydrodynamic force at the provisional position of the interface, is solved in a Lagrangian coordinate using a finite element method. Each governing equation for fluid and structure is implicitly solved using second-order time integrators. The overall second-order temporal accuracy is preserved even with the use of lower-order predictors. A linear stability analysis is also conducted for an ideal case to find the optimal explicit two-step method that provides stable solutions down to the lowest density ratio. With the present weak coupling, three different fluid-structure interaction problems were simulated: flows around an elastically mounted rigid circular cylinder, an elastic beam attached to the base of a stationary circular cylinder, and a flexible plate, respectively. The lowest density ratios providing stable solutions are searched for the first two problems and they are much lower than 1 (ρmin = 0.21 and 0.31, respectively). The simulation results agree well with those from strong coupling suggested here and also from previous numerical and experimental studies, indicating the efficiency and accuracy of the present weak coupling.

Family Life and Developmental Idealism in Yazd, Iran

PubMed Central

Abbasi-Shavazi, Mohammad Jalal; Askari-Nodoushan, Abbas

2012-01-01

BACKGROUND This paper is motivated by the theory that developmental idealism has been disseminated globally and has become an international force for family and demographic change. Developmental idealism is a set of cultural beliefs and values about development and how development relates to family and demographic behavior. It holds that modern societies are causal forces producing modern families, that modern families help to produce modern societies, and that modern family change is to be expected. OBJECTIVE We examine the extent to which developmental idealism has been disseminated in Iran. We also investigate predictors of the dissemination of developmental idealism. METHODS We use survey data collected in 2007 from a sample of women in Yazd, a city in Iran. We examine the distribution of developmental idealism in the sample and the multivariate predictors of developmental idealism. RESULTS We find considerable support for the expectation that many elements of developmental idealism have been widely disseminated. Statistically significant majorities associate development with particular family attributes, believe that development causes change in families, believe that fertility reductions and age-at-marriage increases help foster development, and perceive family trends in Iran headed toward modernity. As predicted, parental education, respondent education, and income affect adherence to developmental idealism. CONCLUSIONS Developmental idealism has been widely disseminated in Yazd, Iran and is related to social and demographic factors in predicted ways. COMMENTS Although our data come from only one city, we expect that developmental idealism has been widely distributed in Iran, with important implications for family and demographic behavior. PMID:22942772

Esophageal aerodynamics in an idealized experimental model of tracheoesophageal speech

NASA Astrophysics Data System (ADS)

Erath, Byron D.; Hemsing, Frank S.

2016-03-01

Flow behavior is investigated in the esophageal tract in an idealized experimental model of tracheoesophageal speech. The tracheoesophageal prosthesis is idealized as a first-order approximation using a straight, constant diameter tube. The flow is scaled according to Reynolds, Strouhal, and Euler numbers to ensure dynamic similarity. Flow pulsatility is produced by a driven orifice that approximates the kinematics of the pharyngoesophageal segment during tracheoesophageal speech. Particle image velocimetry data are acquired in three orthogonal planes as the flow exits the model prosthesis and enters the esophageal tract. Contrary to prior investigations performed in steady flow with the prosthesis oriented in-line with the flow direction, the fluid dynamics are shown to be highly unsteady, suggesting that the esophageal pressure field will be similarly complex. A large vortex ring is formed at the inception of each phonatory cycle, followed by the formation of a persistent jet. This vortex ring appears to remain throughout the entire cycle due to the continued production of vorticity resulting from entrainment between the prosthesis jet and the curved esophageal walls. Mean flow in the axial direction of the esophagus produces significant stretching of the vortex throughout the phonatory cycle. The stagnation point created by the jet impinging on the esophageal wall varies throughout the cycle due to fluctuations in the jet trajectory, which most likely arises due to flow separation within the model prosthesis. Applications to tracheoesophageal speech, including shortcomings of the model and proposed future plans, are discussed.

COTHERM: Modelling fluid-rock interactions in Icelandic geothermal systems

NASA Astrophysics Data System (ADS)

Thien, Bruno; Kosakowski, Georg; Kulik, Dmitrii

2014-05-01

Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced geothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. We model the mineralogical and porosity evolution of Icelandic geothermal systems with 1D and 2D reactive transport models. These geothermal systems are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. The shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. We investigate two contrasting geothermal systems: Krafla, for which the water recharge consists of meteoritic water; and Reykjanes, for which the water recharge mainly consists of seawater. The initial rock composition is a fresh basalt. We use the GEM-Selektor geochemical modeling package [1] for calculation of kinetically controlled mineral equilibria between the rock and the ingression water. We consider basalt minerals dissolution kinetics according to Palandri & Kharaka [2]. Reactive surface areas are assumed to be geometric surface areas, and are corrected using a spherical-particle surface/mass relationship. For secondary minerals, we consider the partial equilibrium assuming that the primary mineral dissolution is slow, and the secondary mineral precipitation is fast. Comparison of our modeling results with the mineralogical assemblages observed in the

Helicity and singular structures in fluid dynamics

PubMed Central

Moffatt, H. Keith

2014-01-01

Helicity is, like energy, a quadratic invariant of the Euler equations of ideal fluid flow, although, unlike energy, it is not sign definite. In physical terms, it represents the degree of linkage of the vortex lines of a flow, conserved when conditions are such that these vortex lines are frozen in the fluid. Some basic properties of helicity are reviewed, with particular reference to (i) its crucial role in the dynamo excitation of magnetic fields in cosmic systems; (ii) its bearing on the existence of Euler flows of arbitrarily complex streamline topology; (iii) the constraining role of the analogous magnetic helicity in the determination of stable knotted minimum-energy magnetostatic structures; and (iv) its role in depleting nonlinearity in the Navier-Stokes equations, with implications for the coherent structures and energy cascade of turbulence. In a final section, some singular phenomena in low Reynolds number flows are briefly described. PMID:24520175

Ideal Cardiovascular Health and Incident Cardiovascular Events

PubMed Central

Ommerborn, Mark J.; Blackshear, Chad T.; Hickson, DeMarc A.; Griswold, Michael E.; Kwatra, Japneet; Djousse, Luc; Clark, Cheryl R.

2016-01-01

Introduction The epidemiology of American Heart Association ideal cardiovascular health (CVH) metrics has not been fully examined in African Americans. This study examines associations of CVH metrics with incident cardiovascular disease (CVD) in the Jackson Heart Study, a longitudinal cohort study of CVD in African Americans. Methods Jackson Heart Study participants without CVD (N=4,702) were followed prospectively between 2000 and 2011. Incidence rates and Cox proportional hazard ratios estimated risks for incident CVD (myocardial infarction, stroke, cardiac procedures, and CVD mortality) associated with seven CVH metrics by sex. Analyses were performed in 2015. Results Participants were followed for a median 8.3 years; none had ideal health on all seven CVH metrics. The prevalence of ideal health was low for nutrition, physical activity, BMI, and blood pressure metrics. The age-adjusted CVD incidence rate (IR) per 1,000 person years was highest for individuals with the least ideal health metrics: zero to one (IR=12.5, 95% CI=9.7, 16.1), two (IR=8.2, 95% CI=6.5, 10.4), three (IR=5.7, 95% CI=4.2, 7.6), and four or more (IR=3.4, 95% CI=2.0, 5.9). Adjusting for covariates, individuals with four or more ideal CVH metrics had lower risks of incident CVD compared with those with zero or one ideal CVH metric (hazard ratio, 0.29; 95% CI=0.17, 0.52; p<0.001). Conclusions African Americans with more ideal CVH metrics have lower risks of incident CVD. Comprehensive preventive behavioral and clinical supports should be intensified to improve CVD risk for African Americans with few ideal CVH metrics. PMID:27539974

Approximation of Nash equilibria and the network community structure detection problem

PubMed Central

2017-01-01

Game theory based methods designed to solve the problem of community structure detection in complex networks have emerged in recent years as an alternative to classical and optimization based approaches. The Mixed Nash Extremal Optimization uses a generative relation for the characterization of Nash equilibria to identify the community structure of a network by converting the problem into a non-cooperative game. This paper proposes a method to enhance this algorithm by reducing the number of payoff function evaluations. Numerical experiments performed on synthetic and real-world networks show that this approach is efficient, with results better or just as good as other state-of-the-art methods. PMID:28467496

Phase equilibria in the iron oxide-cobalt oxide-phosphorus oxide system

NASA Technical Reports Server (NTRS)

De Guire, Mark R.; Prasanna, T. R. S.; Kalonji, Gretchen; O'Handley, Robert C.

1987-01-01

Two novel ternary compounds are noted in the present study of 1000 C solid-state equilibria in the Fe-Co-P-O system's Fe2O3-FePO4-Co3(Po4)2-CoO region: CoFe(PO4)O, which undergoes incongruent melting at 1130 C, and Co3Fe4(PO4)6, whose incongruent melting occurs at 1080 C. The liquidus behavior-related consequences of rapidly solidified cobalt ferrite formation from cobalt ferrite-phosphate melts are discussed with a view to spinel formation. It is suggested that quenching from within the spinel-plus-liquid region may furnish an alternative to quenching a homogeneous melt.

Slippage and boundary layer probed in an almost ideal gas by a nanomechanical oscillator.

PubMed

Defoort, M; Lulla, K J; Crozes, T; Maillet, O; Bourgeois, O; Collin, E

2014-09-26

We measure the interaction between ⁴He gas at 4.2 K and a high-quality nanoelectromechanical string device for its first three symmetric modes (resonating at 2.2, 6.7, and 11 MHz with quality factor Q>0.1×10⁶) over almost 6 orders of magnitude in pressure. This fluid can be viewed as the best experimental implementation of an almost ideal monoatomic and inert gas of which properties are tabulated. The experiment ranges from high pressure where the flow is of laminar Stokes-type presenting slippage down to very low pressures where the flow is molecular. In the molecular regime, when the mean-free path is of the order of the distance between the suspended nanomechanical probe and the bottom of the trench, we resolve for the first time the signature of the boundary (Knudsen) layer onto the measured dissipation. Our results are discussed in the framework of the most recent theories investigating boundary effects in fluids (both analytic approaches and direct simulation Monte Carlo methods).

Active fluids at circular boundaries: swim pressure and anomalous droplet ripening.

PubMed

Jamali, Tayeb; Naji, Ali

2018-06-13

We investigate the swim pressure exerted by non-chiral and chiral active particles on convex or concave circular boundaries. Active particles are modeled as non-interacting and non-aligning self-propelled Brownian particles. The convex and concave circular boundaries are used to model a fixed inclusion immersed in an active bath and a cavity (or container) enclosing the active particles, respectively. We first present a detailed analysis of the role of convex versus concave boundary curvature and of the chirality of active particles in their spatial distribution, chirality-induced currents, and the swim pressure they exert on the bounding surfaces. The results will then be used to predict the mechanical equilibria of suspended fluid enclosures (generically referred to as 'droplets') in a bulk with active particles being present either inside the bulk fluid or within the suspended droplets. We show that, while droplets containing active particles behave in accordance with standard capillary paradigms when suspended in a normal bulk, those containing a normal fluid exhibit anomalous behaviors when suspended in an active bulk. In the latter case, the excess swim pressure results in non-monotonic dependence of the inside droplet pressure on the droplet radius; hence, revealing an anomalous regime of behavior beyond a threshold radius, in which the inside droplet pressure increases upon increasing the droplet size. Furthermore, for two interconnected droplets, mechanical equilibrium can occur also when the droplets have different sizes. We thus identify a regime of anomalous droplet ripening, where two unequal-sized droplets can reach a final state of equal size upon interconnection, in stark contrast with the standard Ostwald ripening phenomenon, implying shrinkage of the smaller droplet in favor of the larger one.

Analytical expression for the correlation function of a hard sphere chain fluid

NASA Astrophysics Data System (ADS)

Chang, Jaeeon; Kim, Hwayong

A closed form expression is given for the correlation function of flexible hard sphere chain fluid. A set of integral equations obtained from Wertheim's multidensity Ornstein-Zernike integral equation theory with the polymer Percus-Yevick ideal chain approximation is considered. Applying the Laplace transformation method to the integral equations and then solving the resulting equations algebraically, the Laplace transforms of individual correlation functions are obtained. By inverse Laplace transformation the inter- and intramolecular radial distribution functions (RDFs) are obtained in closed forms up to 3D(D is segment diameter). These analytical expressions for the RDFs would be useful in developing the perturbation theory of chain fluids.

Acoustic Interaction Forces and Torques Acting on Suspended Spheres in an Ideal Fluid.

PubMed

Lopes, J Henrique; Azarpeyvand, Mahdi; Silva, Glauber T

2016-01-01

In this paper, the acoustic interaction forces and torques exerted by an arbitrary time-harmonic wave on a set of N objects suspended in an inviscid fluid are theoretically analyzed. We utilize the partial-wave expansion method with translational addition theorem and re-expansion of multipole series to solve the related multiple scattering problem. We show that the acoustic interaction force and torque can be obtained using the farfield radiation force and torque formulas. To exemplify the method, we calculate the interaction forces exerted by an external traveling and standing plane wave on an arrangement of two and three olive-oil droplets in water. The droplets' radii are comparable to the wavelength (i.e., Mie scattering regime). The results show that the acoustic interaction forces present an oscillatory spatial distribution which follows the pattern formed by interference between the external and rescattered waves. In addition, acoustic interaction torques arise on the absorbing droplets whenever a nonsymmetric wavefront is formed by the external and rescattered waves' interference.

Predicting Film Genres with Implicit Ideals

PubMed Central

Olney, Andrew McGregor

2013-01-01

We present a new approach to defining film genre based on implicit ideals. When viewers rate the likability of a film, they indirectly express their ideal of what a film should be. Across six studies we investigate the category structure that emerges from likability ratings and the category structure that emerges from the features of film. We further compare these data-driven category structures with human annotated film genres. We conclude that film genres are structured more around ideals than around features of film. This finding lends experimental support to the notion that film genres are set of shifting, fuzzy, and highly contextualized psychological categories. PMID:23423823

Predicting film genres with implicit ideals.

PubMed

Olney, Andrew McGregor

2012-01-01

We present a new approach to defining film genre based on implicit ideals. When viewers rate the likability of a film, they indirectly express their ideal of what a film should be. Across six studies we investigate the category structure that emerges from likability ratings and the category structure that emerges from the features of film. We further compare these data-driven category structures with human annotated film genres. We conclude that film genres are structured more around ideals than around features of film. This finding lends experimental support to the notion that film genres are set of shifting, fuzzy, and highly contextualized psychological categories.

Computational Fluid Dynamics (CFD) simulations of a Heisenberg Vortex Tube

NASA Astrophysics Data System (ADS)

Bunge, Carl; Sitaraman, Hariswaran; Leachman, Jake

2017-11-01

A 3D Computational Fluid Dynamics (CFD) simulation of a Heisenberg Vortex Tube (HVT) is performed to estimate cooling potential with cryogenic hydrogen. The main mechanism driving operation of the vortex tube is the use of fluid power for enthalpy streaming in a highly turbulent swirl in a dual-outlet tube. This enthalpy streaming creates a temperature separation between the outer and inner regions of the flow. Use of a catalyst on the peripheral wall of the centrifuge enables endothermic conversion of para-ortho hydrogen to aid primary cooling. A κ- ɛ turbulence model is used with a cryogenic, non-ideal equation of state, and para-orthohydrogen species evolution. The simulations are validated with experiments and strategies for parametric optimization of this device are presented.

A stepped pressure profile model for internal transport barriers

NASA Astrophysics Data System (ADS)

Hole, Matthew; Hudson, Stuart; Dewar, Robert

2007-11-01

B ∇x et al We develop a multiple interface variational model, comprising multiple Taylor-relaxed plasma regions separated by ideal MHD barriers. The magnetic field in each region is Beltrami, = μ, and the pressure constant. Between these regions the pressure, field strength, and rotational transform may have step changes at the ideal barrier. A principle motivation is the development of a mathematically rigorous ideal MHD model to describe intrinsically 3D equilibria, with nonzero internal pressure, using robust KAM surfaces as the barriers. As each region is locally relaxed however, such a model may also yield reasons for existence of internal transport barriers (ITBs). Focusing on the latter, we build on Hole Nuc. Fus. 47, pp746-753, 2007, which recently studied the stability of a two-interface periodic-cylinder configuration. In this work, we perform a stability scan over pressure and for a two-interface configuration with no jump in , and compare the characteristics of stable equilibria to those of ITB's.

Ideal Theory in Semigroups Based on Intersectional Soft Sets

PubMed Central

Song, Seok Zun; Jun, Young Bae

2014-01-01

The notions of int-soft semigroups and int-soft left (resp., right) ideals are introduced, and several properties are investigated. Using these notions and the notion of inclusive set, characterizations of subsemigroups and left (resp., right) ideals are considered. Using the notion of int-soft products, characterizations of int-soft semigroups and int-soft left (resp., right) ideals are discussed. We prove that the soft intersection of int-soft left (resp., right) ideals (resp., int-soft semigroups) is also int-soft left (resp., right) ideals (resp., int-soft semigroups). The concept of int-soft quasi-ideals is also introduced, and characterization of a regular semigroup is discussed. PMID:25101310

Fluid-structure interaction of two bodies in an inviscid fluid

NASA Astrophysics Data System (ADS)

Tchieu, A. A.; Crowdy, D.; Leonard, A.

2010-10-01

The interaction of two arbitrary bodies immersed in a two-dimensional inviscid fluid is investigated. Given the linear and angular velocities of the bodies, the solution of the potential flow problem with zero circulation around both bodies is reduced to the determination of a suitable Laurent series in a conformally mapped domain that satisfies the boundary conditions. The potential flow solution is then used to determine the force and moment acting on each body by using generalized Blasius formulas. The current formulation is applied to two examples. First, the case of two rigid circular cylinders interacting in an unbounded domain is investigated. The forces on two cylinders with prescribed motion (forced-forced) is determined and compared to previous results for validation purposes. We then study the response of a single "free" cylinder due to the prescribed motion of the other cylinder (forced-free). This forced-free situation is used to justify the hydrodynamic benefits of drafting in aquatic locomotion. In the case of two neutrally buoyant circular cylinders, the aft cylinder is capable of attaining a substantial propulsive force that is the same order of magnitude of its inertial forces. Additionally, the coupled interaction of two cylinders given an arbitrary initial condition (free-free) is studied to show the differences of perfect collisions with and without the presence of an inviscid fluid. For a certain range of collision parameters, the fluid acts to deflect the cylinder paths just enough before the collision to drastically affect the long time trajectories of the bodies. In the second example, the flapping of two plates is explored. It is seen that the interactions between each plate can cause a net force and torque at certain instants in time, but for idealized sinusoidal motions in irrotational potential flow, there is no net force and torque acting at the system center.

Constructing Integrable Full-pressure Full-current Free-boundary Stellarator Magnetohydrodynamic Equilibria

NASA Astrophysics Data System (ADS)

Hudson, S. R.; Monticello, D. A.; Reiman, A. H.; Strickler, D. J.; Hirshman, S. P.

2003-06-01

For the (non-axisymmetric) stellarator class of plasma confinement devices to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux surfaces; however, the inherent lack of a continuous symmetry implies that magnetic islands are guaranteed to exist. Magnetic islands break the smooth topology of nested flux surfaces and chaotic field lines result when magnetic islands overlap. An analogous case occurs with 11/2-dimension Hamiltonian systems where resonant perturbations cause singularities in the transformation to action-angle coordinates and destroy integrability. The suppression of magnetic islands is a critical issue for stellarator design, particularly for small aspect ratio devices. Techniques for `healing' vacuum fields and fixed-boundary plasma equilibria have been developed, but what is ultimately required is a procedure for designing stellarators such that the self-consistent plasma equilibrium currents and the coil currents combine to produce an integrable magnetic field, and such a procedure is presented here for the first time. Magnetic islands in free-boundary full-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the Princeton Iterative Equilibrium Solver [A.H.Reiman & H.S.Greenside, Comp. Phys. Comm., 43:157, 1986.] which iterates the equilibrium equations to obtain the plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible. The method is applied to a candidate plasma and coil design for the National Compact Stellarator eXperiment [G.H.Neilson et.al., Phys. Plas., 7:1911, 2000.].

Acquisition and evaluation of thermodynamic data for morenosite-retgersite equilibria at 0.1 MPa

USGS Publications Warehouse

Chou, I.-Ming; Seal, R.R.

2003-01-01

Metal-sulfate salts in mine drainage environments commonly occur as solid solutions containing Fe, Cu, Mg, Zn, Al, Mn, Ni, Co, Cd, and other elements. Thermodynamic data for some of the end-member salts containing Fe, Cu, Zn, and Mg have been collected and evaluated previously, and the present study extends to the system containing Ni. Morenosite (NiSO4-7H2O)-retgersite (NiSO4-6H2O) equilibria were determined along five humidity buffer curves at 0.1 MPa and between 5 and 22??C. Reversals along these humidity-buffer curves yield In K = 17.58-6303.35/T, where K is the equilibrium constant, and T is temperature in K. The derived standard Gibbs free energy of reaction is 8.84 kJ/mol, which agrees very well with the values of 8.90, 8.83, and 8.85 kJ/mol based on the vapor pressure measurements of Schumb (1923), Bonnell and Burridge (1935), and Stout et al. (1966). respectively. This value also agrees reasonably well with the values of 8.65 and 9.56 kJ/mol calculated from the data compiled by Wagman et al. (1982) and DeKock (1982), respectively. The temperature-humidity relationships defined by this study for dehydration equilibria between morenosite and retgersite explain the more common occurrence of retgersite relative to morenosite in nature.

Determination of melanterite-rozenite and chalcanthite-bonattite equilibria by humidity measurements at 0.1 MPa

USGS Publications Warehouse

Chou, I.-Ming; Seal, R.R.; Hemingway, B.S.

2002-01-01

Melanterite (FeSO4??7H2O)-rozenite (FeSO4??4H2O) and chalcanthite (CuSO4??5H2O)-bonattite (CuSO4??3H2O) equilibria were determined by humidity measurements at 0.1 MPa. Two methods were used; one is the gas-flow-cell method (between 21 and 98 ??C), and the other is the humidity-buffer method (between 21 and 70 ??C). The first method has a larger temperature uncertainty even though it is more efficient. With the aid of humidity buffers, which correspond to a series of saturated binary salt solutions, the second method yields reliable results as demonstrated by very tight reversals along each humidity buffer. These results are consistent with those obtained by the first method, and also with the solubility data reported in the literature. Thermodynamic analysis of these data yields values of 29.231 ?? 0.025 and 22.593 ?? 0.040 kJ/mol for standard Gibbs free energy of reaction at 298.15 K and 0.1 MPa for melanterite-rozenite and chalcanthite-bonattite equilibria, respectively. The methods used in this study hold great potential for unraveling the thermodynamic properties of sulfate salts involved in dehydration reactions at near ambient conditions.

Nash points, Ky Fan inequality and equilibria of abstract economies in Max-Plus and -convexity

NASA Astrophysics Data System (ADS)

Briec, Walter; Horvath, Charles

2008-05-01

-convexity was introduced in [W. Briec, C. Horvath, -convexity, Optimization 53 (2004) 103-127]. Separation and Hahn-Banach like theorems can be found in [G. Adilov, A.M. Rubinov, -convex sets and functions, Numer. Funct. Anal. Optim. 27 (2006) 237-257] and [W. Briec, C.D. Horvath, A. Rubinov, Separation in -convexity, Pacific J. Optim. 1 (2005) 13-30]. We show here that all the basic results related to fixed point theorems are available in -convexity. Ky Fan inequality, existence of Nash equilibria and existence of equilibria for abstract economies are established in the framework of -convexity. Monotone analysis, or analysis on Maslov semimodules [V.N. Kolokoltsov, V.P. Maslov, Idempotent Analysis and Its Applications, Math. Appl., volE 401, Kluwer Academic, 1997; V.P. Litvinov, V.P. Maslov, G.B. Shpitz, Idempotent functional analysis: An algebraic approach, Math. Notes 69 (2001) 696-729; V.P. Maslov, S.N. Samborski (Eds.), Idempotent Analysis, Advances in Soviet Mathematics, Amer. Math. Soc., Providence, RI, 1992], is the natural framework for these results. From this point of view Max-Plus convexity and -convexity are isomorphic Maslov semimodules structures over isomorphic semirings. Therefore all the results of this paper hold in the context of Max-Plus convexity.

Voluminous low-T granite: fluid present partial melting of the crust?

NASA Astrophysics Data System (ADS)

Hand, Martin; Barovich, Karin; Morrissey, Laura; Bockmann, Kiara; Kelsey, David; Williams, Megan

2017-04-01

the granites is their enriched Th concentrations compared to typical Aileron Province sub solidus metapelitic successions. However, based on continuous transects within metasedimentary rocks from a number of different regions that record transitions from sub-solidus assemblages to supra-solidus rocks petrologically characterised by typical fluid-absent peritectic assemblages (central Aileron Province, Broken Hill Zone, Ivrea-Verbano Zone), fluid-absent partial melting does not deplete Th concentrations in the residuum with respect to their sub-solidus protoliths. If these compositional transects are used as a guide to the general behaviour of Th during fluid-absent partial melting, the voluminous Th-enriched granites in the Aileron Province are unlikely to be the products of fluid-absent partial melting. This contention is supported by phase equilibria modelling of sub-solidus metasedimentary units whose detrital zircons match in age the granite-hosted xenocrysts, which indicate that temperatures in excess of 840°C are required to generate significant volumes (ie ≥ 30%) of melt under fluid-absent conditions. However, zircon saturation temperatures for the granites have a weighted mean of 776 ± 4 °C (n = 220). Because the granites contain abundant inheritance, this is an upper-T limit that also suggests fluid-absent partial melting was not the primary mechanism for granite formation. We suggest that voluminous granite formation in the Aileron Province occurred in a fluid-rich regime that was particularly effective at destabilising monazite and liberating Th into melt. Because of the propensity of monazite to destabilise in the presence of fluid, we suggest that high-grade metasedimentary terrains that are notably depleted in Th may be residuum associated with fluid-fluxed melt loss.

Reactive transport simulation via combination of a multiphase-capable transport code for unstructured meshes with a Gibbs energy minimization solver of geochemical equilibria

NASA Astrophysics Data System (ADS)

Fowler, S. J.; Driesner, T.; Hingerl, F. F.; Kulik, D. A.; Wagner, T.

2011-12-01

We apply a new, C++-based computational model for hydrothermal fluid-rock interaction and scale formation in geothermal reservoirs. The model couples the Complex System Modelling Platform (CSMP++) code for fluid flow in porous and fractured media (Matthai et al., 2007) with the Gibbs energy minimization numerical kernel GEMS3K of the GEM-Selektor (GEMS3) geochemical modelling package (Kulik et al., 2010) in a modular fashion. CSMP++ includes interfaces to commercial file formats, accommodating complex geometry construction using CAD (Rhinoceros) and meshing (ANSYS) software. The CSMP++ approach employs finite element-finite volume spatial discretization, implicit or explicit time discretization, and operator splitting. GEMS3K can calculate complex fluid-mineral equilibria based on a variety of equation of state and activity models. A selection of multi-electrolyte aqueous solution models, such as extended Debye-Huckel, Pitzer (Harvie et al., 1984), EUNIQUAC (Thomsen et al., 1996), and the new ELVIS model (Hingerl et al., this conference), makes it well-suited for application to a wide range of geothermal conditions. An advantage of the GEMS3K solver is simultaneous consideration of complex solid solutions (e.g., clay minerals), gases, fluids, and aqueous solutions. Each coupled simulation results in a thermodynamically-based description of the geochemical and physical state of a hydrothermal system evolving along a complex P-T-X path. The code design allows efficient, flexible incorporation of numerical and thermodynamic database improvements. We demonstrate the coupled code workflow and applicability to compositionally and physically complex natural systems relevant to enhanced geothermal systems, where temporally and spatially varying chemical interactions may take place within diverse lithologies of varying geometry. Engesgaard, P. & Kipp, K. L. (1992). Water Res. Res. 28: 2829-2843. Harvie, C. E.; Møller, N. & Weare, J. H. (1984). Geochim. Cosmochim. Acta 48

Maintaining ideal body weight counseling sessions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brammer, S.H.

The purpose of this program is to provide employees with the motivation, knowledge and skills necessary to maintain ideal body weight throughout life. The target audience for this program, which is conducted in an industrial setting, is the employee 40 years of age or younger who is at or near his/her ideal body weight.

On the relationship between kinetic and fluid formalisms for convection in the inner magnetosphere

NASA Astrophysics Data System (ADS)

Song, Yang; Sazykin, Stanislav; Wolf, Richard A.

2008-08-01

In the inner magnetosphere, the plasma flows are mostly slow compared to thermal or Alfvén speeds, but the convection is far away from the ideal magnetohydrodynamic regime since the gradient/curvature drifts become significant. Both kinetic (Wolf, 1983) and two-fluid (Peymirat and Fontaine, 1994; Heinemann, 1999) formalisms have been used to describe plasma dynamics, but it is not fully understood how they relate to each other. We explore the relations among kinetic, fluid, and recently developed "average" (Liu, 2006) models in an attempt to find the simplest yet realistic way to describe the convection. First, we prove analytically that the model of (Liu, 2006), when closed with the assumption of a Maxwellian distribution, is equivalent to the fluid model of (Heinemann, 1999). Second, we analyze the transport of both one-dimensional and two-dimensional Gaussian-shaped blob of hot plasma. For the kinetic case, it is known that the time evolution of such a blob is gradual spreading in time. For the fluid case, Heinemann and Wolf (2001a, 2001b) showed that in a one-dimensional idealized case, the blob separates into two drifting at different speeds. We present a fully nonlinear solution of this case, confirming this behavior but demonstrating what appears to be a shocklike steepening of the faster drifting secondary blob. A new, more realistic two-dimensional example using the dipole geometry with a uniform electric field confirms the one-dimensional solutions. Implications for the numerical simulations of magnetospheric dynamics are discussed.

Experimental Constraints on Hot Spring Fluid Chemistry in Back Arc Basins

NASA Astrophysics Data System (ADS)

Schaen, A. T.; Saccocia, P. J.; Seewald, J.

2010-12-01

decreasing T. SO4 varied inversely with Ca, varying from 35 to 4 mmol/kg from 350 to 250C, respectively. Thus, the presence of alunite in the alteration assemblage yields an extremely acid fluid, depleted in H2S and enriched in SO4 compared to fluids from the PPAQ experiment. These results suggest that the composition of hot spring fluids from back-arc environments is consistent with fluid-mineral equilibria involving acid-sulfate mineral assemblages. Such assemblages may be produced by previous episodes of magmatic degassing. Accordingly, the presence of highly acidic vent fluids may reflect an important role for magmatic fluids during crustal alteration processes, but does not require the presence of an actively degassing magma chamber.

Phase equilibria of the magnesium sulfate-water system to 4 kbars

NASA Technical Reports Server (NTRS)

Hogenboom, D. L.; Kargel, J. S.; Ganasan, J. P.; Lee, L.

1993-01-01

Magnesium sulfate is the most abundant salt in carbonaceous chondrites, and it may be important in the low-temperature igneous evolution and aqueous differentiation of icy satellites and large chondritic asteroids. Accordingly, we are investigating high-pressure phase equilibria in MgSO4-H2O solutions under pressures up to four kbars. An initial report was presented two years ago. This abstract summarizes our results to date including studies of solutions containing 15.3 percent, 17 percent, and 22 percent MgSO4. Briefly, these results demonstrate that increasing pressure causes the eutectic and peritectic compositions to shift to much lower concentrations of magnesium sulfate, and the existence of a new low-density phase of magnesium sulfate hydrate.

a Theoretical Study of Coherent Structures in Nonneutral Plasma Columns

NASA Astrophysics Data System (ADS)

Lund, Steven M.

A ubiquitous feature of experimental and computer simulation studies of magnetically confined pure electron plasmas in cylindrical confinement devices is the formation of nonaxisymmetric (partial/partial theta ne 0) rotating equilibria. In this dissertation, nonaxisymmetric rotating equilibria are investigated theoretically for strongly magnetized, low-density (omega_sp{pe} {2}/omega_sp{ce}{2 } << 1) pure electron plasmas confined in a two-dimensional cylindrical geometry. These dynamic equilibria are also called rotating coherent structures, and are stationary (time-independent) in a frame of reference rotating with angular velocity omega_ {r} = const. about the cylinder axis (r = 0). Radial confinement of the pure electron plasma is provided by a uniform axial magnetic field B_0 {bf e}_{z}, and a grounded, perfectly conducting, cylindrical wall is located at radius r = r_{w}. The analysis is based on a nonrelativistic, guiding-center model in the cold-fluid limit (the continuity and Poisson equations) that treats the electrons as a massless fluid (m_{e} to 0) with E times B flow velocity V _{e} = -(c/B_0)nablaphi times {bf e}_{z}. Within this model, general rotating equilibria with electron density (n_{e} equiv n_{R}(r,theta-omega _{r}t) and electrostatic potential phi equiv phi_{R }(r,theta-omega_{r}t) have the property that the electron density is functionally related to the streamfunction psi _{R} = -ephi_{R} + omega_{r}(eB_0/2c)r^2 by n_{R} = n_{R }(psi_{R}). The streamfunction psi_{R} satisfies the nonlinear equilibrium equation nabla ^2psi_{R} = -4pi e^2n _{R}(psi_{R}) + 2omega_{r}eB_0/c with psi_{R} = omega _{r}(eB_0/2c)r_sp{w }{2} equiv psi_{w } = const. on the cylindrical wall at r = r_{w}. A general methodology for the solution of this equilibrium system is presented and several properties of rotating equilibria are analyzed. Following this analysis, two classes of nonaxisymmetric equilibria are investigated. These two classes of equilibria can have

The Ideal Man and Woman According to University Students

ERIC Educational Resources Information Center

Weinstein, Lawrence; Laverghetta, Antonio V.; Peterson, Scott A.

2009-01-01

The present study determined if the ideal man has changed over the years and who and what the ideal woman is. We asked students at Cameron University to rate the importance of character traits that define the ideal man and woman. Subjects also provided examples of famous people exemplifying the ideal, good, average, and inferior man and woman. We…

Tearing Mode Stability of Evolving Toroidal Equilibria

NASA Astrophysics Data System (ADS)

Pletzer, A.; McCune, D.; Manickam, J.; Jardin, S. C.

2000-10-01

There are a number of toroidal equilibrium (such as JSOLVER, ESC, EFIT, and VMEC) and transport codes (such as TRANSP, BALDUR, and TSC) in our community that utilize differing equilibrium representations. There are also many heating and current drive (LSC and TORRAY), and stability (PEST1-3, GATO, NOVA, MARS, DCON, M3D) codes that require this equilibrium information. In an effort to provide seamless compatibility between the codes that produce and need these equilibria, we have developed two Fortran 90 modules, MEQ and XPLASMA, that serve as common interfaces between these two classes of codes. XPLASMA provides a common equilibrium representation for the heating and current drive applications while MEQ provides common equilibrium and associated metric information needed by MHD stability codes. We illustrate the utility of this approach by presenting results of PEST-3 tearing stability calculations of an NSTX discharge performed on profiles provided by the TRANSP code. Using the MEQ module, the TRANSP equilibrium data are stored in a Fortran 90 derived type and passed to PEST3 as a subroutine argument. All calculations are performed on the fly, as the profiles evolve.

Amniotic fluid: the use of high-dimensional biology to understand fetal well-being.

PubMed

Kamath-Rayne, Beena D; Smith, Heather C; Muglia, Louis J; Morrow, Ardythe L

2014-01-01

Our aim was to review the use of high-dimensional biology techniques, specifically transcriptomics, proteomics, and metabolomics, in amniotic fluid to elucidate the mechanisms behind preterm birth or assessment of fetal development. We performed a comprehensive MEDLINE literature search on the use of transcriptomic, proteomic, and metabolomic technologies for amniotic fluid analysis. All abstracts were reviewed for pertinence to preterm birth or fetal maturation in human subjects. Nineteen articles qualified for inclusion. Most articles described the discovery of biomarker candidates, but few larger, multicenter replication or validation studies have been done. We conclude that the use of high-dimensional systems biology techniques to analyze amniotic fluid has significant potential to elucidate the mechanisms of preterm birth and fetal maturation. However, further multicenter collaborative efforts are needed to replicate and validate candidate biomarkers before they can become useful tools for clinical practice. Ideally, amniotic fluid biomarkers should be translated to a noninvasive test performed in maternal serum or urine.

Impact of bootstrap current and Landau-fluid closure on ELM crashes and transport

NASA Astrophysics Data System (ADS)

Chen, J. G.; Xu, X. Q.; Ma, C. H.; Lei, Y. A.

2018-05-01

Results presented here are from 6-field Landau-Fluid simulations using shifted circular cross-section tokamak equilibria on BOUT++ framework. Linear benchmark results imply that the collisional and collisionless Landau resonance closures make a little difference on linear growth rate spectra which are quite close to the results with the flux limited Spitzer-Härm parallel flux. Both linear and nonlinear simulations show that the plasma current profile plays dual roles on the peeling-ballooning modes that it can drive the low-n peeling modes and stabilize the high-n ballooning modes. For fixed total pressure and current, as the pedestal current decreases due to the bootstrap current which becomes smaller when the density (collisionality) increases, the operational point is shifted downwards vertically in the Jped - α diagram, resulting in threshold changes of different modes. The bootstrap current can slightly increase radial turbulence spreading range and enhance the energy and particle transports by increasing the perturbed amplitude and broadening cross-phase frequency distribution.

Computation of liquid-liquid equilibria and phase stabilities: implications for RH-dependent gas/particle partitioning of organic-inorganic aerosols

NASA Astrophysics Data System (ADS)

Zuend, A.; Marcolli, C.; Peter, T.; Seinfeld, J. H.

2010-08-01

Semivolatile organic and inorganic aerosol species partition between the gas and aerosol particle phases to maintain thermodynamic equilibrium. Liquid-liquid phase separation into an organic-rich and an aqueous electrolyte phase can occur in the aerosol as a result of the salting-out effect. Such liquid-liquid equilibria (LLE) affect the gas/particle partitioning of the different semivolatile compounds and might significantly alter both particle mass and composition as compared to a one-phase particle. We present a new liquid-liquid equilibrium and gas/particle partitioning model, using as a basis the group-contribution model AIOMFAC (Zuend et al., 2008). This model allows the reliable computation of the liquid-liquid coexistence curve (binodal), corresponding tie-lines, the limit of stability/metastability (spinodal), and further thermodynamic properties of multicomponent systems. Calculations for ternary and multicomponent alcohol/polyol-water-salt mixtures suggest that LLE are a prevalent feature of organic-inorganic aerosol systems. A six-component polyol-water-ammonium sulphate system is used to simulate effects of relative humidity (RH) and the presence of liquid-liquid phase separation on the gas/particle partitioning. RH, salt concentration, and hydrophilicity (water-solubility) are identified as key features in defining the region of a miscibility gap and govern the extent to which compound partitioning is affected by changes in RH. The model predicts that liquid-liquid phase separation can lead to either an increase or decrease in total particulate mass, depending on the overall composition of a system and the particle water content, which is related to the hydrophilicity of the different organic and inorganic compounds. Neglecting non-ideality and liquid-liquid phase separations by assuming an ideal mixture leads to an overestimation of the total particulate mass by up to 30% for the composition and RH range considered in the six-component system

Computation of liquid-liquid equilibria and phase stabilities: implications for RH-dependent gas/particle partitioning of organic-inorganic aerosols

NASA Astrophysics Data System (ADS)

Zuend, A.; Marcolli, C.; Peter, T.; Seinfeld, J. H.

2010-05-01

Semivolatile organic and inorganic aerosol species partition between the gas and aerosol particle phases to maintain thermodynamic equilibrium. Liquid-liquid phase separation into an organic-rich and an aqueous electrolyte phase can occur in the aerosol as a result of the salting-out effect. Such liquid-liquid equilibria (LLE) affect the gas/particle partitioning of the different semivolatile compounds and might significantly alter both particle mass and composition as compared to a one-phase particle. We present a new liquid-liquid equilibrium and gas/particle partitioning model, using as a basis the group-contribution model AIOMFAC (Zuend et al., 2008). This model allows the reliable computation of the liquid-liquid coexistence curve (binodal), corresponding tie-lines, the limit of stability/metastability (spinodal), and further thermodynamic properties of the phase diagram. Calculations for ternary and multicomponent alcohol/polyol-water-salt mixtures suggest that LLE are a prevalent feature of organic-inorganic aerosol systems. A six-component polyol-water-ammonium sulphate system is used to simulate effects of relative humidity (RH) and the presence of liquid-liquid phase separation on the gas/particle partitioning. RH, salt concentration, and hydrophilicity (water-solubility) are identified as key features in defining the region of a miscibility gap and govern the extent to which compound partitioning is affected by changes in RH. The model predicts that liquid-liquid phase separation can lead to either an increase or decrease in total particulate mass, depending on the overall composition of a system and the particle water content, which is related to the hydrophilicity of the different organic and inorganic compounds. Neglecting non-ideality and liquid-liquid phase separations by assuming an ideal mixture leads to an overestimation of the total particulate mass by up to 30% for the composition and RH range considered in the six-component system simulation

Asymmetric kinetic equilibria: Generalization of the BAS model for rotating magnetic profile and non-zero electric field

NASA Astrophysics Data System (ADS)

Dorville, Nicolas; Belmont, Gérard; Aunai, Nicolas; Dargent, Jérémy; Rezeau, Laurence

2015-09-01

Finding kinetic equilibria for non-collisional/collisionless tangential current layers is a key issue as well for their theoretical modeling as for our understanding of the processes that disturb them, such as tearing or Kelvin Helmholtz instabilities. The famous Harris equilibrium [E. Harris, Il Nuovo Cimento Ser. 10 23, 115-121 (1962)] assumes drifting Maxwellian distributions for ions and electrons, with constant temperatures and flow velocities; these assumptions lead to symmetric layers surrounded by vacuum. This strongly particular kind of layer is not suited for the general case: asymmetric boundaries between two media with different plasmas and different magnetic fields. The standard method for constructing more general kinetic equilibria consists in using Jeans theorem, which says that any function depending only on the Hamiltonian constants of motion is a solution to the steady Vlasov equation [P. J. Channell, Phys. Fluids (1958-1988) 19, 1541 (1976); M. Roth et al., Space Sci. Rev. 76, 251-317 (1996); and F. Mottez, Phys. Plasmas 10, 1541-1545 (2003)]. The inverse implication is however not true: when using the motion invariants as variables instead of the velocity components, the general stationary particle distributions keep on depending explicitly of the position, in addition to the implicit dependence introduced by these invariants. The standard approach therefore strongly restricts the class of solutions to the problem and probably does not select the most physically reasonable. The BAS (Belmont-Aunai-Smets) model [G. Belmont et al., Phys. Plasmas 19, 022108 (2012)] used for the first time the concept of particle accessibility to find new solutions: considering the case of a coplanar-antiparallel magnetic field configuration without electric field, asymmetric solutions could be found while the standard method can only lead to symmetric ones. These solutions were validated in a hybrid simulation [N. Aunai et al., Phys. Plasmas (1994-present) 20

Asymmetric kinetic equilibria: Generalization of the BAS model for rotating magnetic profile and non-zero electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorville, Nicolas, E-mail: nicolas.dorville@lpp.polytechnique.fr; Belmont, Gérard; Aunai, Nicolas

Finding kinetic equilibria for non-collisional/collisionless tangential current layers is a key issue as well for their theoretical modeling as for our understanding of the processes that disturb them, such as tearing or Kelvin Helmholtz instabilities. The famous Harris equilibrium [E. Harris, Il Nuovo Cimento Ser. 10 23, 115–121 (1962)] assumes drifting Maxwellian distributions for ions and electrons, with constant temperatures and flow velocities; these assumptions lead to symmetric layers surrounded by vacuum. This strongly particular kind of layer is not suited for the general case: asymmetric boundaries between two media with different plasmas and different magnetic fields. The standard methodmore » for constructing more general kinetic equilibria consists in using Jeans theorem, which says that any function depending only on the Hamiltonian constants of motion is a solution to the steady Vlasov equation [P. J. Channell, Phys. Fluids (1958–1988) 19, 1541 (1976); M. Roth et al., Space Sci. Rev. 76, 251–317 (1996); and F. Mottez, Phys. Plasmas 10, 1541–1545 (2003)]. The inverse implication is however not true: when using the motion invariants as variables instead of the velocity components, the general stationary particle distributions keep on depending explicitly of the position, in addition to the implicit dependence introduced by these invariants. The standard approach therefore strongly restricts the class of solutions to the problem and probably does not select the most physically reasonable. The BAS (Belmont-Aunai-Smets) model [G. Belmont et al., Phys. Plasmas 19, 022108 (2012)] used for the first time the concept of particle accessibility to find new solutions: considering the case of a coplanar-antiparallel magnetic field configuration without electric field, asymmetric solutions could be found while the standard method can only lead to symmetric ones. These solutions were validated in a hybrid simulation [N. Aunai et al., Phys. Plasmas (1994

Three-Dimensional Multi-fluid Moment Simulation of Ganymede

NASA Astrophysics Data System (ADS)

Wang, L.; Germaschewski, K.; Hakim, A.; Bhattacharjee, A.; Dong, C.

2016-12-01

Plasmas in space environments, such as solar wind and Earth's magnetosphere, are often constituted of multiple species. Conventional MHD-based, single-fluid systems, have additional complications when multiple fluid species are introduced. We suggest space application of an alternative multi-fluid moment approach, treating each species on equal footing using exact evolution equations for moments of their distribution function, and electromagnetic fields through full Maxwell equations. Non-ideal effects like Hall effect, inertia, and even tensorial pressures, are self-consistently embedded without the need to explicitly solve a complicated Ohm's law. Previously, we have benchmarked this approach in classical test problems like the Orszag-Tang vortex and GEM reconnection challenge problem. Recently, we performed three-dimensional two-fluid simulation of the magnetosphere of Ganymede, using both five-moment (scalar pressures) and ten-moment (tensorial pressures) models. In both models, the formation of Alfven wing structure due to subsonic inflow is correctly captured, and the magnetic field data agree well with in-situ measurements from the Galileo flyby G8. The ten-moment simulation also showed the contribution of pressure tensor divergence to the reconnecting electric field. Initial results of coupling to state-of-art global simulation codes like OpenGGCM will also be shown, which will in the future provide a rigorous way for integration of ionospheric physics.

Idealism and materialism in perception.

PubMed

Rose, David; Brown, Dora

2015-01-01

Koenderink (2014, Perception, 43, 1-6) has said most Perception readers are deluded, because they believe an 'All Seeing Eye' observes an objective reality. We trace the source of Koenderink's assertion to his metaphysical idealism, and point to two major weaknesses in his position-namely, its dualism and foundationalism. We counter with arguments from modern philosophy of science for the existence of an objective material reality, contrast Koenderink's enactivism to his idealism, and point to ways in which phenomenology and cognitive science are complementary and not mutually exclusive.

Complex Fluids at Interfaces and Interfaces of Complex Fluids

NASA Astrophysics Data System (ADS)

Nouri, Mariam

The present thesis deals with two independent projects and is consequently divided into two parts. The first part details a computational study of the fluid structure of ring-shaped molecules and their positional and orientational molecular organizations in different degrees of confinement, while the second part concerns an experimental study of phase behavior and interfacial phenomena in confined colloid-polymer systems. In the first part, ring-shaped molecules are studied using Monte Carlo simulation techniques in one, two and three dimensions. The model used to describe ring-shaped molecules is composed of hard-spheres linked together to form planar rigid rings. For rings of various sizes and for a wide range of densities, positional and orientational orderings are reported in forms of pair distribution functions of the ring centers and correlation functions of the ring normal orientations. Special emphasis is given to understand structural formation at interfaces, i.e., the structure and orderings of these molecules when they are confined to two dimensions. In a plane but the rings themselves are free to rotate around all axes, nematic ordering is observed at sufficiently high densities. In the second part, phase equilibria of confined aqueous colloid-polymer systems are studied experimentally using fluorescence microscopy. Aqueous mixtures of fluorescent polystyrene spheres and polyacrylamide are confined between a glass slide and a coverslip. The phase diagram is determined as a function of the colloidal and polymer concentrations. Liquid-liquid phase coexistence between a colloid-rich phase and a polymer-rich phase occurs at intermediate polymer concentrations, while liquid-solid phase coexistence between a polymer-rich liquid and a colloid-rich solid is observed at high polymer concentrations. Interfacial thickness and tension of the interface between these coexisting phases are measured using image analysis techniques. It is also observed that the colloid

Effects of gravity reduction on phase equilibria. Part 1: Unary and binary isostructural solids

NASA Technical Reports Server (NTRS)

Larson, D. J., Jr.

1975-01-01

Analysis of the Skylab II M553 Experiment samples resulted in the hypothesis that the reduced gravity environment was altering the melting and solidification reactions. A theoretical study was conducted to define the conditions under which such alteration of phase relations is feasible, determine whether it is restricted to space processing, and, if so, ascertain which alloy systems or phase reactions are most likely to demonstrate such effects. Phase equilibria of unary and binary systems with a single solid phase (unary and isomorphous) were considered.

Thermodynamic foundations of applications of ab initio methods for determination of the adsorbate equilibria: hydrogen at the GaN(0001) surface.

PubMed

Kempisty, Pawel; Strąk, Paweł; Sakowski, Konrad; Kangawa, Yoshihiro; Krukowski, Stanisław

2017-11-08

Thermodynamic foundations of ab initio modeling of vapor-solid and vapor-surface equilibria are introduced. The chemical potential change is divided into enthalpy and entropy terms. The enthalpy path passes through vapor-solid transition at zero temperature. The entropy path avoids the singular point at zero temperature passing a solid-vapor transition under normal conditions, where evaporation entropy is employed. In addition, the thermal changes are calculated. The chemical potential difference contribution of the following terms: vaporization enthalpy, vaporization entropy, the temperature-entropy related change, the thermal enthalpy change and mechanical pressure is obtained. The latter term is negligibly small for the pressure typical for epitaxy. The thermal enthalpy change is two orders smaller than the first three terms which have to be taken into account explicitly. The configurational vaporization entropy change is derived for adsorption processes. The same formulation is derived for vapor-surface equilibria using hydrogen at the GaN(0001) surface as an example. The critical factor is the dependence of the enthalpy of evaporation (desorption energy) on the pinning of the Fermi level bringing a drastic change of the value from 2.24 eV to -2.38 eV. In addition it is shown that entropic contributions considerable change the hydrogen equilibrium pressure over the GaN(0001) surface by several orders of magnitude. Thus a complete and exact formulation of vapor-solid and vapor-surface equilibria is presented.

Connection between plasma response and resonant magnetic perturbation (RMP) edge localized mode (ELM) suppression in DIII-D [Connection between plasma response and RMP ELM suppression in DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wingen, Andreas; Ferraro, Nathaniel M.; Shafer, Morgan W.

Calculations of the plasma response to applied non-axisymmetric fields in several DIII-D discharges show that predicted displacements depend strongly on the edge current density. This result is found using both a linear two-fluid-MHD model (M3D-C1) and a nonlinear ideal-MHD model (VMEC). Furthermore, it is observed that the probability of a discharge being edge localized mode (ELM)-suppressed is most closely related to the edge current density, as opposed to the pressure gradient. It is found that discharges with a stronger kink response are closer to the peeling–ballooning stability limit in ELITE simulations and eventually cross into the unstable region, causing ELMsmore » to reappear. Thus for effective ELM suppression, the RMP has to prevent the plasma from generating a large kink response, associated with ELM instability. Experimental observations are in agreement with the finding; discharges which have a strong kink response in the MHD simulations show ELMs or ELM mitigation during the RMP phase of the experiment, while discharges with a small kink response in the MHD simulations are fully ELM suppressed in the experiment by the applied resonant magnetic perturbation. The results are cross-checked against modeled 3D ideal MHD equilibria using the VMEC code. The procedure of constructing optimal 3D equilibria for diverted H-mode discharges using VMEC is presented. As a result, kink displacements in VMEC are found to scale with the edge current density, similar to M3D-C1, but the displacements are smaller. A direct correlation in the flux surface displacements to the bootstrap current is shown.« less

Connection between plasma response and resonant magnetic perturbation (RMP) edge localized mode (ELM) suppression in DIII-D [Connection between plasma response and RMP ELM suppression in DIII-D

DOE PAGES

Wingen, Andreas; Ferraro, Nathaniel M.; Shafer, Morgan W.; ...

2015-09-03

Calculations of the plasma response to applied non-axisymmetric fields in several DIII-D discharges show that predicted displacements depend strongly on the edge current density. This result is found using both a linear two-fluid-MHD model (M3D-C1) and a nonlinear ideal-MHD model (VMEC). Furthermore, it is observed that the probability of a discharge being edge localized mode (ELM)-suppressed is most closely related to the edge current density, as opposed to the pressure gradient. It is found that discharges with a stronger kink response are closer to the peeling–ballooning stability limit in ELITE simulations and eventually cross into the unstable region, causing ELMsmore » to reappear. Thus for effective ELM suppression, the RMP has to prevent the plasma from generating a large kink response, associated with ELM instability. Experimental observations are in agreement with the finding; discharges which have a strong kink response in the MHD simulations show ELMs or ELM mitigation during the RMP phase of the experiment, while discharges with a small kink response in the MHD simulations are fully ELM suppressed in the experiment by the applied resonant magnetic perturbation. The results are cross-checked against modeled 3D ideal MHD equilibria using the VMEC code. The procedure of constructing optimal 3D equilibria for diverted H-mode discharges using VMEC is presented. As a result, kink displacements in VMEC are found to scale with the edge current density, similar to M3D-C1, but the displacements are smaller. A direct correlation in the flux surface displacements to the bootstrap current is shown.« less

Body fluid matrix evaluation on a Roche cobas 8000 system.

PubMed

Owen, William E; Thatcher, Mindy L; Crabtree, Karolyn J; Greer, Ryan W; Strathmann, Frederick G; Straseski, Joely A; Genzen, Jonathan R

2015-09-01

Chemical analysis of body fluids is commonly requested by physicians. Because most commercial FDA-cleared clinical laboratory assays are not validated by diagnostic manufacturers for "non-serum" and "non-plasma" specimens, laboratories may need to complete additional validation studies to comply with regulatory requirements regarding body fluid testing. The objective of this report is to perform recovery studies to evaluate potential body fluid matrix interferences for commonly requested chemistry analytes. Using an IRB-approved protocol, previously collected clinical body fluid specimens (biliary/hepatic, cerebrospinal, dialysate, drain, pancreatic, pericardial, peritoneal, pleural, synovial, and vitreous) were de-identified and frozen (-20°C) until experiments were performed. Recovery studies (spiking with high concentration serum, control, and/or calibrator) were conducted using 10% spiking solution by volume; n=5 specimens per analyte/body fluid investigated. Specimens were tested on a Roche cobas 8000 system (c502, c702, e602, and ISE modules). In all 80 analyte/body fluid combinations investigated (including amylase, total bilirubin, urea nitrogen, carbohydrate antigen 19-9, carcinoembryonic antigen, cholesterol, chloride, creatinine, glucose, potassium, lactate dehydrogenase, lipase, rheumatoid factor, sodium, total protein, triglycerides, and uric acid), the average percent recovery was within predefined acceptable limits (less than ±10% from the calculated ideal recovery). The present study provides evidence against the presence of any systematic matrix interference in the analyte/body fluid combinations investigated on the Roche cobas 8000 system. Such findings support the utility of ongoing body fluid validation initiatives conducted to maintain compliance with regulatory requirements. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Medical learning curves and the Kantian ideal.

PubMed

Le Morvan, P; Stock, B

2005-09-01

A hitherto unexamined problem for the "Kantian ideal" that one should always treat patients as ends in themselves, and never only as a means to other ends, is explored in this paper. The problem consists of a prima facie conflict between this Kantian ideal and the reality of medical practice. This conflict arises because, at least presently, medical practitioners can only acquire certain skills and abilities by practising on live, human patients, and given the inevitability and ubiquity of learning curves, this learning requires some patients to be treated only as a means to this end. A number of ways of attempting to establish the compatibility of the Kantian Ideal with the reality of medical practice are considered. Each attempt is found to be unsuccessful. Accordingly, until a way is found to reconcile them, we conclude that the Kantian ideal is inconsistent with the reality of medical practice.

Medical learning curves and the Kantian ideal

PubMed Central

Le Morvan, P; Stock, B

2005-01-01

A hitherto unexamined problem for the "Kantian ideal" that one should always treat patients as ends in themselves, and never only as a means to other ends, is explored in this paper. The problem consists of a prima facie conflict between this Kantian ideal and the reality of medical practice. This conflict arises because, at least presently, medical practitioners can only acquire certain skills and abilities by practising on live, human patients, and given the inevitability and ubiquity of learning curves, this learning requires some patients to be treated only as a means to this end. A number of ways of attempting to establish the compatibility of the Kantian Ideal with the reality of medical practice are considered. Each attempt is found to be unsuccessful. Accordingly, until a way is found to reconcile them, we conclude that the Kantian ideal is inconsistent with the reality of medical practice. PMID:16131552

The Existence and Stability Analysis of the Equilibria in Dengue Disease Infection Model

NASA Astrophysics Data System (ADS)

Anggriani, N.; Supriatna, A. K.; Soewono, E.

2015-06-01

In this paper we formulate an SIR (Susceptible - Infective - Recovered) model of Dengue fever transmission with constant recruitment. We found a threshold parameter K0, known as the Basic Reproduction Number (BRN). This model has two equilibria, disease-free equilibrium and endemic equilibrium. By constructing suitable Lyapunov function, we show that the disease- free equilibrium is globally asymptotic stable whenever BRN is less than one and when it is greater than one, the endemic equilibrium is globally asymptotic stable. Numerical result shows the dynamic of each compartment together with effect of multiple bio-agent intervention as a control to the dengue transmission.

Scaling-law equilibria for calcium in canopy-type models of the solar chromosphere

NASA Technical Reports Server (NTRS)

Jones, H. P.

1982-01-01

Scaling laws for resonance line formation are used to obtain approximate excitation and ionization equilibria for a three-level model of singly ionized calcium. The method has been developed for and is applied to the study of magnetograph response in the 8542 A infrared triplet line to magnetostatic canopies which schematically model diffuse, nearly horizontal fields in the low solar chromosphere. For this application, the method is shown to be efficient and semi-quantitative, and the results indicate the type and range of effects on calcium-line radiation which result from reduced gas pressure inside the magnetic regions.

Quantitative body fluid proteomics in medicine - A focus on minimal invasiveness.

PubMed

Csősz, Éva; Kalló, Gergő; Márkus, Bernadett; Deák, Eszter; Csutak, Adrienne; Tőzsér, József

2017-02-05

Identification of new biomarkers specific for various pathological conditions is an important field in medical sciences. Body fluids have emerging potential in biomarker studies especially those which are continuously available and can be collected by non-invasive means. Changes in the protein composition of body fluids such as tears, saliva, sweat, etc. may provide information on both local and systemic conditions of medical relevance. In this review, our aim is to discuss the quantitative proteomics techniques used in biomarker studies, and to present advances in quantitative body fluid proteomics of non-invasively collectable body fluids with relevance to biomarker identification. The advantages and limitations of the widely used quantitative proteomics techniques are also presented. Based on the reviewed literature, we suggest an ideal pipeline for body fluid analyses aiming at biomarkers discoveries: starting from identification of biomarker candidates by shotgun quantitative proteomics or protein arrays, through verification of potential biomarkers by targeted mass spectrometry, to the antibody-based validation of biomarkers. The importance of body fluids as a rich source of biomarkers is discussed. Quantitative proteomics is a challenging part of proteomics applications. The body fluids collected by non-invasive means have high relevance in medicine; they are good sources for biomarkers used in establishing the diagnosis, follow up of disease progression and predicting high risk groups. The review presents the most widely used quantitative proteomics techniques in body fluid analysis and lists the potential biomarkers identified in tears, saliva, sweat, nasal mucus and urine for local and systemic diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Surprising Impact of Remote Groups on the Folding-Unfolding and Dimer-Chain Equilibria of Bifunctionl H-Bonding Unimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Rui; Cheng, Shuang; Baker, Erin Shammel

2016-01-28

Oligoamide 1, consisting of two H-bonding units linked by a trimethylene linker, was previously found to form a very stable, folded dimer. In this work, replacing the side chains and end groups of 1 led to derivatives that show the surprising impact of end groups on the folding and dimer-chain equilibria of the resultant molecules.

Molecular equilibria and condensation sequences in carbon rich gases

NASA Technical Reports Server (NTRS)

Sharp, C. M.; Wasserburg, G. J.

1993-01-01

Chemical equilibria in stellar atmospheres have been investigated by many authors. Lattimer, Schramm, and Grossman presented calculations in both O rich and C rich environments and predicted possible presolar condensates. A recent paper by Cherchneff and Barker considered a C rich composition with PAH's included in the calculations. However, the condensation sequences of C bearing species have not been investigated in detail. In a carbon rich gas surrounding an AGB star, it is often assumed that graphite (or diamond) condenses out before TiC and SiC. However, Lattimer et al. found some conditions under which TiC condenses before graphite. We have performed molecular equilibrium calculations to establish the stability fields of C(s), TiC(s), and SiC(s) and other high temperature phases under conditions of different pressures and C/O. The preserved presolar interstellar dust grains so far discovered in meteorites are graphite, diamond, SiC, TiC, and possibly Al2O3.

Multidimensional equilibria and their stability in copolymer-solvent mixtures

NASA Astrophysics Data System (ADS)

Glasner, Karl; Orizaga, Saulo

2018-06-01

This paper discusses localized equilibria which arise in copolymer-solvent mixtures. A free boundary problem associated with the sharp-interface limit of a density functional model is used to identify both lamellar and concentric domain patterns composed of a finite number of layers. Stability of these morphologies is studied through explicit linearization of the free boundary evolution. For the multilayered lamellar configuration, transverse instability is observed for sufficiently small dimensionless interfacial energies. Additionally, a crossover between small and large wavelength instabilities is observed depending on whether solvent-polymer or monomer-monomer interfacial energy is dominant. Concentric domain patterns resembling multilayered micelles and vesicles exhibit bifurcations wherein they only exist for sufficiently small dimensionless interfacial energies. The bifurcation of large radii vesicle solutions is studied analytically, and a crossover from a supercritical case with only one solution branch to a subcritical case with two is observed. Linearized stability of these configurations shows that azimuthal perturbation may lead to instabilities as interfacial energy is decreased.

[The style of leadership idealized by nurses].

PubMed

Higa, Elza de Fátima Ribeiro; Trevizan, Maria Auxiliadora

2005-01-01

This study focuses on nursing leadership on the basis of Grid theories. According to the authors, these theories are an alternative that allows for leadership development in nursing. The research aimed to identify and analyze the style of leadership idealized by nurses, according to their own view, and to compare the styles of leadership idealized by nurses between the two research institutions. Study subjects were 13 nurses. The results show that nurses at both institutions equally mention they idealize style 9.9, followed by 5.5 and 1.9, with a tendency to reject styles 9.1 and 1.1.

Competition and equilibria in electricity markets based on two-settlement system: A conjectural variation approach

NASA Astrophysics Data System (ADS)

Watts, David

This dissertation studies electricity markets based on two-settlement systems and applies the concept of conjectural variation (CV) as a tool for representing different levels of competitiveness in the market. Some recent theoretical works are addressed to support the use of CV as a solution concept. A notion of consistency is introduced to make the level of competitiveness of the market endogenous, and allows finding consistent CV equilibria and the corresponding conditions for existence of equilibria. First, a case is studied in which firms hold exogenous levels of forward commitments. Then, backward induction and sub-game perfection are used to solve sequentially for the spot and forward market equilibrium. This allows analyzing how firms take positions in the forward market, based on considering their later impact on the spot market. It is concluded that positions taken in the forward market depend largely on firms expectations about the competitiveness of both the spot and the forward market. Forward markets are welfare enhancing even if they are not as competitive as the associated spot market as long as they are not too oligopolistie. The above formulation is used to model a dynamic scenario to analyze market stability, linking this research to Dr. Alvarado's earlier research on market stability. This brings about interesting trade offs between market power and market stability.

Concepts of Ideal and Nonideal Explosives.

DTIC Science & Technology

1981-12-01

Akst and J. Hershkowitz, "Explosive Performance Modification by Cosolidifaction of Ammonium Nitrate with Fuels ," Technical Report 4987, Picatinny...explosives Equations of state Diameter effect Ammonium nitrate 20. ASSrRACr (ca’mes r w re t N netwezy ad identity by block number) The purpose of...this report is to stimulate discussion on the nonideality of ammonium nitrate and its composite explosives. The concept of ideal and non- ideal

On axisymmetric resistive magnetohydrodynamic equilibria with flow free of Pfirsch-Schlüter diffusion

NASA Astrophysics Data System (ADS)

Throumoulopoulos, G. N.; Tasso, H.

2003-06-01

The equilibrium of an axisymmetric magnetically confined plasma with anisotropic resistivity and incompressible flows parallel to the magnetic field is investigated within the framework of the magnetohydrodynamic (MHD) theory by keeping the convective flow term in the momentum equation. It turns out that the stationary states are determined by a second-order elliptic partial differential equation for the poloidal magnetic flux function ψ along with a decoupled Bernoulli equation for the pressure identical in form with the respective ideal MHD equations; equilibrium consistent expressions for the resistivities η∥ and η⊥ parallel and perpendicular to the magnetic field are also derived from Ohm's and Faraday's laws. Unlike in the case of stationary states with isotropic resistivity and parallel flows [G. N. Throumoulopoulos and H. Tasso, J. Plasma Phys. 64, 601 (2000)] the equilibrium is compatible with nonvanishing poloidal current densities. Also, although exactly Spitzer resistivities either η∥(ψ) or η⊥(ψ) are not allowed, exact solutions with vanishing poloidal electric fields can be constructed with η∥ and η⊥ profiles compatible with roughly collisional resistivity profiles, i.e., profiles having a minimum close to the magnetic axis, taking very large values on the boundary and such that η⊥>η∥. For equilibria with vanishing flows satisfying the relation (dP/dψ)(dI2/dψ)>0, where P and I are the pressure and the poloidal current functions, the difference η⊥-η∥ for the reversed-field pinch scaling, Bp≈Bt, is nearly two times larger than that for the tokamak scaling, Bp≈0.1Bt (Bp and Bt are the poloidal and toroidal magnetic-field components). The particular resistive equilibrium solutions obtained in the present work, inherently free of—but not inconsistent with—Pfirsch-Schlüter diffusion, indicate that parallel flows might result in a reduction of the diffusion observed in magnetically confined plasmas.

Ideal strength of bcc molybdenum and niobium

NASA Astrophysics Data System (ADS)

Luo, Weidong; Roundy, D.; Cohen, Marvin L.; Morris, J. W.

2002-09-01

The behavior of bcc Mo and Nb under large strain was investigated using the ab initio pseudopotential density-functional method. We calculated the ideal shear strength for the {211}<111> and {011}<111> slip systems and the ideal tensile strength in the <100> direction, which are believed to provide the minimum shear and tensile strengths. As either material is sheared in either of the two systems, it evolves toward a stress-free tetragonal structure that defines a saddle point in the strain-energy surface. The inflection point on the path to this tetragonal ``saddle-point'' structure sets the ideal shear strength. When either material is strained in tension along <100>, it initially follows the tetragonal, ``Bain,'' path toward a stress-free fcc structure. However, before the strained crystal reaches fcc, its symmetry changes from tetragonal to orthorhombic; on continued strain it evolves toward the same tetragonal saddle point that is reached in shear. In Mo, the symmetry break occurs after the point of maximum tensile stress has been passed, so the ideal strength is associated with the fcc extremum as in W. However, a Nb crystal strained in <100> becomes orthorhombic at tensile stress below the ideal strength. The ideal tensile strength of Nb is associated with the tetragonal saddle point and is caused by failure in shear rather than tension. In dimensionless form, the ideal shear and tensile strengths of Mo (τ*=τm/G111=0.12, σ*=σm/E100=0.078) are essentially identical to those previously calculated for W. Nb is anomalous. Its dimensionless shear strength is unusually high, τ*=0.15, even though the saddle-point structure that causes it is similar to that in Mo and W, while its dimensionless tensile strength, σ*=0.079, is almost the same as that of Mo and W, even though the saddle-point structure is quite different.

Magnetogasdynamics shock waves in a rotational axisymmetric non-ideal gas with increasing energy and conductive and radiative heat-fluxes

NASA Astrophysics Data System (ADS)

Nath, Gorakh

2016-07-01

Self-similar solutions are obtained for one-dimensional adiabatic flow behind a magnetogasdynamics cylindrical shock wave propagating in a rotational axisymmetric non ideal gas with increasing energy and conductive and radiative heat fluxes in presence of an azimuthal magnetic field. The fluid velocities and the azimuthal magnetic field in the ambient medium are assume to be varying and obeying power laws. In order to find the similarity solutions the angular velocity of the ambient medium is taken to be decreasing as the distance from the axis increases. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be the diffusion type for an optically thick grey gas model. The thermal conductivity and the absorption coefficient are assumed to vary with temperature and density. The effects of the presence of radiation and conduction, the non-idealness of the gas and the magnetic field on the shock propagation and the flow behind the shock are investigated.

Verification of the ideal magnetohydrodynamic response at rational surfaces in the VMEC code

DOE PAGES

Lazerson, Samuel A.; Loizu, Joaquim; Hirshman, Steven; ...

2016-01-13

The VMEC nonlinear ideal MHD equilibrium code [S. P. Hirshman and J. C. Whitson, Phys. Fluids 26, 3553 (1983)] is compared against analytic linear ideal MHD theory in a screw-pinch-like configuration. The focus of such analysis is to verify the ideal MHD response at magnetic surfaces which possess magnetic transform (ι) which is resonant with spectral values of the perturbed boundary harmonics. A large aspect ratio circular cross section zero-beta equilibrium is considered. This equilibrium possess a rational surface with safety factor q = 2 at a normalized flux value of 0.5. A small resonant boundary perturbation is introduced, excitingmore » a response at the resonant rational surface. The code is found to capture the plasma response as predicted by a newly developed analytic theory that ensures the existence of nested flux surfaces by allowing for a jump in rotational transform (ι=1/q). The VMEC code satisfactorily reproduces these theoretical results without the necessity of an explicit transform discontinuity (Δι) at the rational surface. It is found that the response across the rational surfaces depends upon both radial grid resolution and local shear (dι/dΦ, where ι is the rotational transform and Φ the enclosed toroidal flux). Calculations of an implicit Δι suggest that it does not arise due to numerical artifacts (attributed to radial finite differences in VMEC) or existence conditions for flux surfaces as predicted by linear theory (minimum values of Δι). Scans of the rotational transform profile indicate that for experimentally relevant levels of transform shear the response becomes increasing localised. Furthermore, careful examination of a large experimental tokamak equilibrium, with applied resonant fields, indicates that this shielding response is present, suggesting the phenomena is not limited to this verification exercise.« less

Ideal and Nonideal Reasoning in Educational Theory

ERIC Educational Resources Information Center

Jaggar, Alison M.

2015-01-01

The terms "ideal theory" and "nonideal theory" are used in contemporary Anglophone political philosophy to identify alternative methodological approaches for justifying normative claims. Each term is used in multiple ways. In this article Alison M. Jaggar disentangles several versions of ideal and nonideal theory with a view to…

Idealized cultural beliefs about gender: implications for mental health.

PubMed

Mahalingam, Ramaswami; Jackson, Benita

2007-12-01

In this paper, we examined the relationship between culture-specific ideals (chastity, masculinity, caste beliefs) and self-esteem, shame and depression using an idealized cultural model proposed by Mahalingam (2006, In: Mahalingam R (ed) Cultural psychology of immigrants. Lawrence Erlbaum, Mahwah, NJ, pp 1-14). Participants were from communities with a history of extreme male-biased sex ratios in Tamilnadu, India (N = 785). We hypothesized a dual-process model of self-appraisals suggesting that achieving idealized cultural identities would increase both self-esteem and shame, with the latter leading to depression, even after controlling for key covariates. We tested this using structural equation modeling. The proposed idealized cultural identities model had an excellent fit (CFI = 0.99); the effect of idealized identities on self-esteem, shame and depression differed by gender. Idealized beliefs about gender relate to psychological well-being in gender specific ways in extreme son preference communities. We discuss implications of these findings for future research and community-based interventions.

Fluid heterogeneity during granulite facies metamorphism in the Adirondacks: stable isotope evidence

USGS Publications Warehouse

Valley, J.W.; O'Neil, J.R.

1984-01-01

The preservation of premetamorphic, whole-rock oxygen isotope ratios in Adirondack metasediments shows that neither these rocks nor adjacent anorthosites and gneisses have been penetrated by large amounts of externally derived, hot CO2-H2O fluids during granulite facies metamorphism. This conclusion is supported by calculations of the effect of fluid volatilization and exchange and is also independently supported by petrologic and phase equilibria considerations. The data suggest that these rocks were not an open system during metamorphism; that fluid/rock ratios were in many instances between 0.0 and 0.1; that externally derived fluids, as well as fluids derived by metamorphic volatilization, rose along localized channels and were not pervasive; and thus that no single generalization can be applied to metamorphic fluid conditions in the Adirondacks. Analyses of 3 to 4 coexisting minerals from Adirondack marbles show that isotopic equilibrium was attained at the peak of granulite and upper amphibolite facies metamorphism. Thus the isotopic compositions of metamorphic fluids can be inferred from analyses of carbonates and fluid budgets can be constructed. Carbonates from the granulite facies are on average, isotopically similar to those from lower grade or unmetamorphosed limestones of the same age showing that no large isotopic shifts accompanied high grade metamorphism. Equilibrium calculations indicate that small decreases in ??18O, averaging 1 permil, result from volatilization reactions for Adirondack rock compositions. Additional small differences between amphibolite and granulite facies marbles are due to systematic lithologie differences. The range of Adirondack carbonate ??18O values (12.3 to 27.2) can be explained by the highly variable isotopic compositions of unmetamorphosed limestones in conjunction with minor 18O and 13C depletions caused by metamorphic volatilization suggesting that many (and possibly most) marbles have closely preserved their

Investigation of shock waves in the relativistic Riemann problem: A comparison of viscous fluid dynamics to kinetic theory

NASA Astrophysics Data System (ADS)

Bouras, I.; Molnár, E.; Niemi, H.; Xu, Z.; El, A.; Fochler, O.; Greiner, C.; Rischke, D. H.

2010-08-01

We solve the relativistic Riemann problem in viscous matter using the relativistic Boltzmann equation and the relativistic causal dissipative fluid-dynamical approach of Israel and Stewart. Comparisons between these two approaches clarify and point out the regime of validity of second-order fluid dynamics in relativistic shock phenomena. The transition from ideal to viscous shocks is demonstrated by varying the shear viscosity to entropy density ratio η/s. We also find that a good agreement between these two approaches requires a Knudsen number Kn<1/2.

Investigation of shock waves in the relativistic Riemann problem: A comparison of viscous fluid dynamics to kinetic theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bouras, I.; El, A.; Fochler, O.

2010-08-15

We solve the relativistic Riemann problem in viscous matter using the relativistic Boltzmann equation and the relativistic causal dissipative fluid-dynamical approach of Israel and Stewart. Comparisons between these two approaches clarify and point out the regime of validity of second-order fluid dynamics in relativistic shock phenomena. The transition from ideal to viscous shocks is demonstrated by varying the shear viscosity to entropy density ratio {eta}/s. We also find that a good agreement between these two approaches requires a Knudsen number Kn<1/2.

Multiple Equilibria Associated with Response of the ITCZ to Seasonal SST Forcing

NASA Technical Reports Server (NTRS)

Chao, Winston C.

1998-01-01

Supported by numerical experiment results, the abrupt change of the location of the intertropical convergence zone (ITCZ), from the equatorial trough flow regime to the monsoon trough flow regime is interpreted as a subcritical instability. The existence of these multiple quasi-equilibria is due to the balance of two "forces" on the ITCZ: one toward the equator, due to the earth's rotation, has a nonlinear latitudinal dependence; and the other toward the latitude of the sea surface (or ground) temperature peak has a relatively linear latitudinal dependence. This work pivots on the finding that the ITCZ and Hadley circulation can still exist without the pole-to-equator gradient of radiative-convective equilibrium temperature.

Susceptibility for thin ideal media and eating styles.

PubMed

Anschutz, Doeschka J; Engels, Rutger C M E; Van Strien, Tatjana

2008-03-01

This study examined the relations between susceptibility for thin ideal media and restrained, emotional and external eating, directly and indirectly through body dissatisfaction. Thin ideal media susceptibility, body dissatisfaction and eating styles were measured in a sample of 163 female students. Structural equation modelling was used for analyses, controlling for BMI. Higher susceptibility for thin ideal media was directly related to higher scores on all eating styles, and indirectly related to higher restrained and emotional eating through elevated levels of body dissatisfaction. So, thin ideal media susceptibility was not only related to restraint through body dissatisfaction, but also directly. Emotional eaters might be more vulnerable for negative affect, whereas external eaters might be more sensitive to external cues in general.

FDA’s Nozzle Numerical Simulation Challenge: Non-Newtonian Fluid Effects and Blood Damage

PubMed Central

Trias, Miquel; Arbona, Antonio; Massó, Joan; Miñano, Borja; Bona, Carles

2014-01-01

Data from FDA’s nozzle challenge–a study to assess the suitability of simulating fluid flow in an idealized medical device–is used to validate the simulations obtained from a numerical, finite-differences code. Various physiological indicators are computed and compared with experimental data from three different laboratories, getting a very good agreement. Special care is taken with the derivation of blood damage (hemolysis). The paper is focused on the laminar regime, in order to investigate non-Newtonian effects (non-constant fluid viscosity). The code can deal with these effects with just a small extra computational cost, improving Newtonian estimations up to a ten percent. The relevance of non-Newtonian effects for hemolysis parameters is discussed. PMID:24667931

Probing free jet expansions of supercritical fluids

NASA Astrophysics Data System (ADS)

Christen, W.; Rademann, K.

2009-10-01

Attempting to improve the comprehension of supersonic molecular beams at elevated pressures we present a comparative study of thermodynamic descriptions of the terminal flow velocity in free jet expansions. As model system we choose carbon dioxide due to its widespread utilization in supercritical fluid technology. Numerical results for the thermodynamic quantities are obtained using a high accuracy equation of state explicit in the Helmholtz free energy. The influence of pressure and temperature on the beam velocity is investigated for a broad range of stagnation conditions. A consistent physical picture is obtained for calculations employing the initial and final molar enthalpies, while enormous discrepancies are found for descriptions based on the molar isobaric heat capacity or the heat capacity ratio. The deviations are particularly pronounced at the gas-liquid phase transition and in the vicinity of the critical point and can be related to the diverse assumptions of ideal gas behavior. It is shown that computations using real fluid enthalpies permit to assess the fraction of condensation in supersonic jets.

Stability of DIII-D high-performance, negative central shear discharges

DOE PAGES

Hanson, Jeremy M.; Berkery, John W.; Bialek, James M.; ...

2017-03-20

Tokamak plasma experiments on the DIII-D device demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor q min exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H 89 = 2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided asmore » long as a threshold minimum safety factor value q min > 2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to β N values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to β N > 4 by broadening the current profile. Furthermore, this path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.« less

Stability of DIII-D high-performance, negative central shear discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, Jeremy M.; Berkery, John W.; Bialek, James M.

Tokamak plasma experiments on the DIII-D device demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor q min exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H 89 = 2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided asmore » long as a threshold minimum safety factor value q min > 2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to β N values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to β N > 4 by broadening the current profile. Furthermore, this path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.« less

Promoting Spiritual Ideals through Design Thinking in Public Schools

ERIC Educational Resources Information Center

Tan, Charlene; Wong, Yew-Leong

2012-01-01

Against a backdrop of the debates on religious education in public or state schools, we argue for the introduction of "spiritual ideals" into the public school curriculum. We distinguish our notion of spiritual ideals from "religious ideals" as conceptualised by De Ruyter and Merry. While we agree with De Ruyter and Merry that…

Evaluation of the Utility of Static and Adaptive Mesh Refinement for Idealized Tropical Cyclone Problems in a Spectral Element Shallow Water Model

DTIC Science & Technology

2015-04-09

where u is the zonal momentum per unit mass, v is the meridional momentum per unit mass, h is the fluid depth, and f is the Coriolis parameter. An...from each cyclone advects the other116 creating a net cyclonic motion (the Fujiwhara effect ; Fujiwhara 1921) (case 2 idealization).117 In Fig. 2c, the...the interaction of the two136 vortices cause a net cyclonic motion (the Fujiwhara effect ).137 The initial condition for the binary vortex interaction

Metamorphism and partial melting of ordinary chondrites: Calculated phase equilibria

NASA Astrophysics Data System (ADS)

Johnson, T. E.; Benedix, G. K.; Bland, P. A.

2016-01-01

Constraining the metamorphic pressures (P) and temperatures (T) recorded by meteorites is key to understanding the size and thermal history of their asteroid parent bodies. New thermodynamic models calibrated to very low P for minerals and melt in terrestrial mantle peridotite permit quantitative investigation of high-T metamorphism in ordinary chondrites using phase equilibria modelling. Isochemical P-T phase diagrams based on the average composition of H, L and LL chondrite falls and contoured for the composition and abundance of olivine, ortho- and clinopyroxene, plagioclase and chromite provide a good match with values measured in so-called equilibrated (petrologic type 4-6) samples. Some compositional variables, in particular Al in orthopyroxene and Na in clinopyroxene, exhibit a strong pressure dependence when considered over a range of several kilobars, providing a means of recognising meteorites derived from the cores of asteroids with radii of several hundred kilometres, if such bodies existed at that time. At the low pressures (<1 kbar) that typify thermal metamorphism, several compositional variables are good thermometers. Although those based on Fe-Mg exchange are likely to have been reset during slow cooling, those based on coupled substitution, in particular Ca and Al in orthopyroxene and Na in clinopyroxene, are less susceptible to retrograde diffusion and are potentially more faithful recorders of peak conditions. The intersection of isopleths of these variables may allow pressures to be quantified, even at low P, permitting constraints on the minimum size of parent asteroid bodies. The phase diagrams predict the onset of partial melting at 1050-1100 °C by incongruent reactions consuming plagioclase, clinopyroxene and orthopyroxene, whose compositions change abruptly as melting proceeds. These predictions match natural observations well and support the view that type 7 chondrites represent a suprasolidus continuation of the established petrologic

Energy transfer between a passing vortex ring and a flexible plate in an ideal quiescent fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, JiaCheng; Peterson, Sean D., E-mail: peterson@mme.uwaterloo.ca; Porfiri, Maurizio

Recent advancements in highly deformable smart materials have lead to increasing interest in small-scale energy harvesting research for powering low consumption electronic devices. One such recent experimental study by Goushcha et al. explored energy harvesting from a passing vortex ring by a cantilevered smart material plate oriented parallel to and offset from the path of the ring in an otherwise quiescent fluid. The present study focuses on modeling this experimental study using potential flow to facilitate optimization of the energy extraction from the passing ring to raise the energy harvesting potential of the device. The problem is modeled in two-dimensionsmore » with the vortex ring represented as a pair of counter-rotating free vortices. Vortex pair parameters are determined to match the convection speed of the ring in the experiments, as well as the imposed pressure loading on the plate. The plate is approximated as a Kirchhoff-Love plate and represented as a finite length vortex sheet in the fluid domain. The analytical model matches experimental measurements, including the tip displacement, the integrated force along the entire plate length as a function of vortex ring position, and the pressure along the plate. The potential flow solution is employed in a parametric study of the governing dimensionless parameters in an effort to guide the selection of plate properties for optimal energy harvesting performance. Results of the study indicate an optimal set of plate properties for a given vortex ring configuration, in which the time-scale of vortex advection matches that of the plate vibration.« less

Childhood Lifestyle and Clinical Determinants of Adult Ideal

PubMed Central

Laitinen, Tomi T.; Pahkala, Katja; Venn, Alison; Woo, Jessica G; Oikonen, Mervi; Dwyer, Terence; Mikkilä, Vera; Hutri-Kähönen, Nina; Smith, Kylie J.; Gall, Seana L.; Morrison, John A.; Viikari, Jorma S.A.; Raitakari, Olli T.; Magnussen, Costan G.; Juonala, Markus

2013-01-01

Background The American Heart Association recently defined ideal cardiovascular health by simultaneous presence of seven health behaviors and factors. The concept is associated with cardiovascular disease incidence, and cardiovascular disease and all-cause mortality. To effectively promote ideal cardiovascular health already early in life, childhood factors predicting future ideal cardiovascular health should be investigated. Our aim was thus to comprehensively explore childhood determinants of adult ideal cardiovascular health in population based cohorts from three continents. Methods The sample comprised a total of 4409 participants aged 3–19 years at baseline from the Cardiovascular Risk in Young Finns Study (YFS; N=1883) from Finland, Childhood Determinants of Adult Health Study (CDAH; N=1803) from Australia and Princeton Follow-up Study (PFS; N=723) from the United States. Participants were re-examined 19–31 years later when aged 30–48 years. Results In multivariable analyses, independent childhood predictors of adult ideal cardiovascular health were family socioeconomic status (P<0.01; direct association) and BMI (P<0.001; inverse association) in all cohorts. In addition, blood pressure (P=0.007), LDL-cholesterol (P<0.001) and parental smoking (P=0.006) in the YFS, and own smoking (P=0.001) in CDAH were inversely associated with future ideal cardiovascular health. Conclusions Among several lifestyle and clinical indicators studied, higher family socioeconomic status and non-smoking (parental/own) in childhood independently predict ideal cardiovascular health in adulthood. As atherosclerotic cardiovascular diseases are rooted in childhood, our findings suggest that special attention could be paid to children who are from low socioeconomic status families, and who smoke or whose parents smoke, to prevent cardiovascular disease morbidity and mortality. PMID:24075574

The Mathematics of Aggregation, Interdependence, Organizations and Systems of Nash Equilibria (NE): A Replacement for Game Theory

DTIC Science & Technology

2011-06-01

there a free-market economist in the House?, American Journal of Economics and Sociology, 66(2): 309-334. Jasny, B. R., Zahn, L.M., & Marshall, E...1   The Mathematics of Aggregation, Interdependence, Organizations and Systems of Nash equilibria (NE): A replacement for Game Theory...level data to group, organization and systems levels, making it one of social science’s biggest challenges, if not the most important (Giles, 2011). For

Extremal equilibria for reaction-diffusion equations in bounded domains and applications

NASA Astrophysics Data System (ADS)

Rodríguez-Bernal, Aníbal; Vidal-López, Alejandro

We show the existence of two special equilibria, the extremal ones, for a wide class of reaction-diffusion equations in bounded domains with several boundary conditions, including non-linear ones. They give bounds for the asymptotic dynamics and so for the attractor. Some results on the existence and/or uniqueness of positive solutions are also obtained. As a consequence, several well-known results on the existence and/or uniqueness of solutions for elliptic equations are revisited in a unified way obtaining, in addition, information on the dynamics of the associated parabolic problem. Finally, we ilustrate the use of the general results by applying them to the case of logistic equations. In fact, we obtain a detailed picture of the positive dynamics depending on the parameters appearing in the equation.

Group contribution methodology based on the statistical associating fluid theory for heteronuclear molecules formed from Mie segments.

PubMed

Papaioannou, Vasileios; Lafitte, Thomas; Avendaño, Carlos; Adjiman, Claire S; Jackson, George; Müller, Erich A; Galindo, Amparo

2014-02-07

compounds not included in the development of group parameters are demonstrated. The performance of the theory is also critically assessed with predictions of the fluid-phase behavior (vapor-liquid and liquid-liquid equilibria) and excess thermodynamic properties of a variety of binary mixtures, including polymer solutions, where very good agreement with the experimental data is seen, without the need for adjustable mixture parameters.

On the union of graded prime ideals

NASA Astrophysics Data System (ADS)

Uregen, Rabia Nagehan; Tekir, Unsal; Hakan Oral, Kursat

2016-01-01

In this paper we investigate graded compactly packed rings, which is defined as; if any graded ideal I of R is contained in the union of a family of graded prime ideals of R, then I is actually contained in one of the graded prime ideals of the family. We give some characterizations of graded compactly packed rings. Further, we examine this property on h - Spec(R). We also define a generalization of graded compactly packed rings, the graded coprimely packed rings. We show that R is a graded compactly packed ring if and only if R is a graded coprimely packed ring whenever R be a graded integral domain and h - dim R = 1.

Thermodynamic characteristics of the acid-base equilibria of ethylenediamine- N, N'-diglutaric acid in aqueous solutions using calorimetric data

NASA Astrophysics Data System (ADS)

Gridchin, S. N.; Nikol'skii, V. M.

2017-10-01

The enthalpies of reaction of betaine group neutralization of ethylenediamine- N, N'-diglutaric acid (H4L) at 298.15 K and at different values of ionic strength of 0.1, 0.5, 1.0 (KNO3) is measured by direct calorimetry. The standard thermodynamic characteristics of the protolytic equilibria of H4L are calculated.

Why Education in Public Schools Should Include Religious Ideals

ERIC Educational Resources Information Center

de Ruyter, Doret J.; Merry, Michael S.

2009-01-01

This article aims to open a new line of debate about religion in public schools by focusing on religious ideals. The article begins with an elucidation of the concept "religious ideals" and an explanation of the notion of reasonable pluralism, in order to be able to explore the dangers and positive contributions of religious ideals and their…

Idealization of the analyst by the young adult.

PubMed

Chused, J F

1987-01-01

Idealization is an intrapsychic process that serves many functions. In addition to its use defensively and for gratification of libidinal and aggressive drive derivatives, it can contribute to developmental progression, particularly during late adolescence and young adulthood. During an analysis, it is important to recognize all the determinants of idealization, including those related to the reworking of developmental conflicts. If an analyst understands idealization solely as a manifestation of pathology, he may interfere with his patient's use of it for the development of autonomous functioning.

Phase Equilibria of Sn-Co-Cu Ternary System

NASA Astrophysics Data System (ADS)

Chen, Yu-Kai; Hsu, Chia-Ming; Chen, Sinn-Wen; Chen, Chih-Ming; Huang, Yu-Chih

2012-10-01

Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys' development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523 K, 1073 K, and 1273 K (250 °C, 800 °C, and 1000 °C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn3Co2Cu8, was found. The solubilities of Cu in the α-CoSn3 and CoSn2 phases at 523 K (250 °C) are 4.2 and 1.6 at. pct, respectively, while the Cu solubility in the α-Co3Sn2 phase is as high as 20.0 at. pct. The Cu solubility increases with temperature and is around 30.0 at. pct in the β-Co3Sn2 at 1073 K (800 °C). The Co solubility in the η-Cu6Sn5 phase is also significant and is 15.5 at. pct at 523 K (250 °C).

How important is non-ideal physics in simulations of sub-Eddington accretion on to spinning black holes?

NASA Astrophysics Data System (ADS)

Foucart, Francois; Chandra, Mani; Gammie, Charles F.; Quataert, Eliot; Tchekhovskoy, Alexander

2017-09-01

Black holes with accretion rates well below the Eddington rate are expected to be surrounded by low-density, hot, geometrically thick accretion discs. This includes the two black holes being imaged at subhorizon resolution by the Event Horizon Telescope. In these discs, the mean free path for Coulomb interactions between charged particles is large, and the accreting matter is a nearly collisionless plasma. Despite this, numerical simulations have so far modelled these accretion flows using ideal magnetohydrodynamics. Here, we present the first global, general relativistic, 3D simulations of accretion flows on to a Kerr black hole including the non-ideal effects most likely to affect the dynamics of the disc: the anisotropy between the pressure parallel and perpendicular to the magnetic field, and the heat flux along magnetic field lines. We show that for both standard and magnetically arrested discs, the pressure anisotropy is comparable to the magnetic pressure, while the heat flux remains dynamically unimportant. Despite this large pressure anisotropy, however, the time-averaged structure of the accretion flow is strikingly similar to that found in simulations treating the plasma as an ideal fluid. We argue that these similarities are largely due to the interchangeability of the viscous and magnetic shear stresses as long as the magnetic pressure is small compared to the gas pressure, and to the subdominant role of pressure/viscous effects in magnetically arrested discs. We conclude by highlighting outstanding questions in modelling the dynamics of low-collisionality accretion flows.

Thermodynamic characteristics of the protolytic equilibria of tetramethylenediamine- N,N,N', N'-tetraacetic acid

NASA Astrophysics Data System (ADS)

Gridchin, S. N.; Nikol'skii, V. M.

2014-04-01

The stepwise dissociation constants of tetramethylenediamine- N,N,N', N'-tetraacetic acid (H4L) are determined by means of potentiometry at 298.15 K and ionic strength values of 0.1, 0.5, and 1.0 (KNO3). The heat effects of the dissociation of the betaine groups of the complexone are measured by direct calorimetry. The standard thermodynamic characteristics of the protolytic equilibria of H4L are calculated via combined use of the results from thermochemical and potentiometric studies performed under identical experimental conditions. Our results are compared with the corresponding data on relative compounds.

Versatile fluid-mixing device for cell and tissue microgravity research applications.

PubMed

Wilfinger, W W; Baker, C S; Kunze, E L; Phillips, A T; Hammerstedt, R H

1996-01-01

Microgravity life-science research requires hardware that can be easily adapted to a variety of experimental designs and working environments. The Biomodule is a patented, computer-controlled fluid-mixing device that can accommodate these diverse requirements. A typical shuttle payload contains eight Biomodules with a total of 64 samples, a sealed containment vessel, and a NASA refrigeration-incubation module. Each Biomodule contains eight gas-permeable Silastic T tubes that are partitioned into three fluid-filled compartments. The fluids can be mixed at any user-specified time. Multiple investigators and complex experimental designs can be easily accommodated with the hardware. During flight, the Biomodules are sealed in a vessel that provides two levels of containment (liquids and gas) and a stable, investigator-controlled experimental environment that includes regulated temperature, internal pressure, humidity, and gas composition. A cell microencapsulation methodology has also been developed to streamline launch-site sample manipulation and accelerate postflight analysis through the use of fluorescent-activated cell sorting. The Biomodule flight hardware and analytical cell encapsulation methodology are ideally suited for temporal, qualitative, or quantitative life-science investigations.

The effect of intraocular gas and fluid volumes on intraocular pressure.

PubMed

Simone, J N; Whitacre, M M

1990-02-01

Large increases in the intraocular pressure (IOP) of postoperative gas-containing eyes may require the removal of gas or fluid to reduce the IOP to the normal range. Application of the ideal gas law to Friedenwald's equation provides a mathematical model of the relationship between IOP, intraocular gas and fluid volumes, and the coefficient of scleral rigidity. This mathematic model shows that removal of a given volume of gas or fluid produces an identical decrease in IOP and that the more gas an eye contains, the greater the volume reduction necessary to reduce the pressure. Application of the model shows that the effective coefficient of scleral rigidity is low (mean K, 0.0021) in eyes with elevated IOP that have undergone vitrectomy and retinal cryopexy and very low (mean K, 0.0013) in eyes with elevated IOP that have undergone placement of a scleral buckle and band. By using the appropriate mean coefficient of rigidity, the volume of material to be aspirated to produce a given decrease in IOP can be predicted with clinically useful accuracy.

Moral identity as moral ideal self: links to adolescent outcomes.

PubMed

Hardy, Sam A; Walker, Lawrence J; Olsen, Joseph A; Woodbury, Ryan D; Hickman, Jacob R

2014-01-01

The purposes of this study were to conceptualize moral identity as moral ideal self, to develop a measure of this construct, to test for age and gender differences, to examine links between moral ideal self and adolescent outcomes, and to assess purpose and social responsibility as mediators of the relations between moral ideal self and outcomes. Data came from a local school sample (Data Set 1: N = 510 adolescents; 10-18 years of age) and a national online sample (Data Set 2: N = 383 adolescents; 15-18 years of age) of adolescents and their parents. All outcome measures were parent-report (Data Set 1: altruism, moral personality, aggression, and cheating; Data Set 2: environmentalism, school engagement, internalizing, and externalizing), whereas other variables were adolescent-report. The 20-item Moral Ideal Self Scale showed good reliability, factor structure, and validity. Structural equation models demonstrated that, even after accounting for moral identity internalization, in Data Set 1 moral ideal self positively predicted altruism and moral personality and negatively predicted aggression, whereas in Data Set 2 moral ideal self positively predicted environmentalism and negatively predicted internalizing and externalizing symptoms. Further, purpose and social responsibility mediated most relations between moral ideal self and the outcomes in Data Set 2. Moral ideal self was unrelated to age but differentially predicted some outcomes across age. Girls had higher levels of moral ideal self than boys, although moral identity did not differentially predict outcomes between genders. Thus, moral ideal self is a salient element of moral identity and may play a role in morally relevant adolescent outcomes. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Vapor-liquid equilibria for R-22, R-134a, R-125, and R-32/125 with a polyol ester lubricant: Measurements and departure from ideality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martz, W.L.; Burton, C.M.; Jacobi, A.M.

1996-11-01

The effect of a polyol ester lubricant on equilibrium pressure, liquid density, and viscosity is presented for R-22, R-125, and R-134a at varying temperatures and concentrations. Preliminary vapor-liquid equilibrium (VLE) data and miscibility observations are also presented for an R-32/R-125 blend (50%/50%) with the ISO 68 polyol ester (POE). Real-gas behavior is modeled using the vapor-phase fugacity, and vapor pressure effects on liquid fugacities are taken into account with the Poynting effect. Positive, negative, and mixed deviations form the Lewis-Randall rule are observed in the activity coefficient behavior. Departures from ideality are related to molecular size differences, intermolecular forces inmore » the mixture, and other factors. The data are discussed in the context of previous results for other refrigerants and thermodynamic modeling of refrigerant and oil mixtures.« less

On stability and turbulence of fluid flows

NASA Technical Reports Server (NTRS)

Heisenberg, Werner

1951-01-01

This investigation is divided into two parts, the treatment of the stability problem of fluid flows on the one hand, and that of the turbulent motion on the other. The first part summarizes all previous investigations under a unified point of view, that is, sets up as generally as possible the conditions under which a profile possesses unstable or stable characteristics, and indicates the methods for solution of the stability equation for any arbitrary velocity profile and for calculation of the critical Reynolds number for unstable profiles. In the second part, under certain greatly idealizing assumptions, differential equations for the turbulent motions are derived and from them qualitative information about several properties of the turbulent velocity distribution is obtained.

Molecular dynamics equation of state for nonpolar geochemical fluids

NASA Astrophysics Data System (ADS)

Duan, Zhenhao; Møller, Nancy; Wears, John H.

1995-04-01

Remarkable agreement between molecular dynamics simulations and experimental measurements has been obtained for methane for a large range of intensive variables, including those corresponding to liquid/vapor coexistence. Using a simple Lennard-Jones potential the simulations not only predict the PVT properties up to 2000°C and 20,000 bar with errors less than 1.5%, but also reproduce phase equilibria well below 0°C with accuracy close to experiment. This two-parameter molecular dynamics equation of state (SOS) is accurate for a much larger range of temperatures and pressures than our previously published EOS with a total fifteen parameters or that of Angus et al. (1978) with thirty-three parameters. By simple scaling, it is possible to predict PVT and phase equilibria of other nonpolar and weakly polar species.

Vapor Pressure Plus: An Experiment for Studying Phase Equilibria in Water, with Observation of Supercooling, Spontaneous Freezing, and the Triple Point

ERIC Educational Resources Information Center

Tellinghuisen, Joel

2010-01-01

Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature…

Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Atmospheres: Development of Technique

NASA Astrophysics Data System (ADS)

Fallah-Mehrjardi, Ata; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni

2017-12-01

The majority of primary pyrometallurgical copper making processes involve the formation of two immiscible liquid phases, i.e., matte product and the slag phase. There are significant gaps and discrepancies in the phase equilibria data of the slag and the matte systems due to issues and difficulties in performing the experiments and phase analysis. The present study aims to develop an improved experimental methodology for accurate characterisation of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system under controlled atmospheres. The experiments involve high-temperature equilibration of synthetic mixtures on silica substrates in CO/CO2/SO2/Ar atmospheres, rapid quenching of samples into water, and direct composition measurement of the equilibrium phases using Electron Probe X-ray Microanalysis (EPMA). A four-point-test procedure was applied to ensure the achievement of equilibrium, which included the following: (i) investigation of equilibration as a function of time, (ii) assessment of phase homogeneity, (iii) confirmation of equilibrium by approaching from different starting conditions, and (iv) systematic analysis of the reactions specific to the system. An iterative improved experimental methodology was developed using this four-point-test approach to characterize the complex multi-component, multi-phase equilibria with high accuracy and precision. The present study is a part of a broader overall research program on the characterisation of the multi-component (Cu-Fe-O-S-Si-Al-Ca-Mg), multi-phase (gas/slag/matte/metal/solids) systems with minor elements (Pb, Zn, As, Bi, Sn, Sb, Ag, and Au).

Effect of hole size on fluid dynamics of a posterior-chamber phakic intraocular lens with a central perforation by using computational fluid dynamics.

PubMed

Kawamorita, Takushi; Shimizu, Kimiya; Shoji, Nobuyuki

2016-04-01

A modified implantable collamer lens (ICL) with a central hole with a diameter of 0.36 mm, referred to as a hole-ICL, was created to improve aqueous humour circulation. The aim of this study is to investigate the ideal hole size in a hole-ICL from the standpoint of the fluid dynamic characteristics of the aqueous humour using computational fluid dynamics. Fluid dynamics simulation using an ICL was performed with thermal-hydraulic analysis software FloEFD V 12.2 (Mentor Graphics Corp.). In the simulation, three-dimensional eye models based on a modified Liou-Brennan model eye with a conventional ICL (Model ICM, Staar Surgical) and a hole-ICL were used. The hole-ICL was -9.0 dioptres (D) and 12.0 mm in length, with an optic zone of 5.5 mm. The vaulting was 0.50 mm. The quantity of aqueous humour produced by the ciliary body was set at 2.80 μL/min. Flow distribution between the anterior surface of the crystalline lens and the posterior surface of the ICL was calculated, and trajectory analysis was performed. With an increase in the central hole size, the velocity of the aqueous humour increased, with the peak velocity occurring at a diameter of approximately 0.4 mm. Once the diameter had increased above 0.4 mm, the velocity then decreased. The velocity difference between the cases of a central hole size of 0.1 mm and 0.2 mm was significant. The desirable central hole size was 0.2 mm or larger in terms of flow dynamics. The current model, based on a central hole size of 0.36 mm, was close to ideal. The optimisation of the hole size should be performed based on results from a long-term clinical study so as to analyse the incidence rate of secondary cataract and optical performance.

[Challenges and risks in the development of the ego ideal in adolescence].

PubMed

Helbing-Tietze, Brigitte

2003-11-01

The author proposes to speak of representations concerning the ideal self, the ideal relationship, the ideal society instead of ego ideal. An active self develops ideals and uses them as standards for orientation, to regulate the affects, and to fulfill needs. The different ideals often do not fit together and are therefore difficult to realize. Adolescents normally refuse their parents' ideals and create new ones with the help of their peers. This developmental step is full of challenges and risks as will be explained in this article.

Computational Fluid Dynamics Analysis of Thoracic Aortic Dissection

NASA Astrophysics Data System (ADS)

Tang, Yik; Fan, Yi; Cheng, Stephen; Chow, Kwok

2011-11-01

Thoracic Aortic Dissection (TAD) is a cardiovascular disease with high mortality. An aortic dissection is formed when blood infiltrates the layers of the vascular wall, and a new artificial channel, the false lumen, is created. The expansion of the blood vessel due to the weakened wall enhances the risk of rupture. Computational fluid dynamics analysis is performed to study the hemodynamics of this pathological condition. Both idealized geometry and realistic patient configurations from computed tomography (CT) images are investigated. Physiological boundary conditions from in vivo measurements are employed. Flow configuration and biomechanical forces are studied. Quantitative analysis allows clinicians to assess the risk of rupture in making decision regarding surgical intervention.

Some physical aspects of fluid-fluxed melting

NASA Astrophysics Data System (ADS)

Patiño Douce, A.

2012-04-01

Fluid-fluxed melting is thought to play a crucial role in the origin of many terrestrial magmas. We can visualize the fundamental physics of the process as follows. An infinitesimal amount of fluid infiltrates dry rock at the temperature of its dry solidus. In order to restore equilibrium the temperature must drop, so that enthalpy is released and immediately reabsorbed as enthalpy of melting. The amount of melt produced must be such that the energy balance and thermodynamic equilibrium conditions are simultaneously satisfied. We wish to understand how an initially dry rock melts in response to progressive fluid infiltration, under both batch and fractional melting constraints. The simplest physical model for this process is a binary system in which one of the components makes up a pure solid phase and the other component a pure fluid phase, and in which a binary melt phase exists over certain temperature range. Melting point depression is calculated under the assumption of ideal mixing. The equations of energy balance and thermodynamic equilibrium are solved simultaneously for temperature and melt fraction, using an iterative procedure that allows addition of fluid in infinitesimal increments. Batch melting and fractional melting are simulated by allowing successive melt increments to remain in the system (batch) or not (fractional). Despite their simplified nature, these calculations reveal some important aspects of fluid-fluxed melting. The model confirms that, if the solubility of the fluid in the melt is sufficiently high, fluid fluxed melting is an efficient mechanism of magma generation. One might expect that the temperature of the infiltrating fluid would have a significant effect on melt productivity, but the results of the calculations show this not to be the case, because a relatively small mass of low molecular weight fluid has a strong effect on the melting point of minerals with much higher molecular weights. The calculations reveal the somewhat

The ideal subject distance for passport pictures.

PubMed

Verhoff, Marcel A; Witzel, Carsten; Kreutz, Kerstin; Ramsthaler, Frank

2008-07-04

In an age of global combat against terrorism, the recognition and identification of people on document images is of increasing significance. Experiments and calculations have shown that the camera-to-subject distance - not the focal length of the lens - can have a significant effect on facial proportions. Modern passport pictures should be able to function as a reference image for automatic and manual picture comparisons. This requires a defined subject distance. It is completely unclear which subject distance, in the taking of passport photographs, is ideal for the recognition of the actual person. We show here that the camera-to-subject distance that is perceived as ideal is dependent on the face being photographed, even if the distance of 2m was most frequently preferred. So far the problem of the ideal camera-to-subject distance for faces has only been approached through technical calculations. We have, for the first time, answered this question experimentally with a double-blind experiment. Even if there is apparently no ideal camera-to-subject distance valid for every face, 2m can be proposed as ideal for the taking of passport pictures. The first step would actually be the determination of a camera-to-subject distance for the taking of passport pictures within the standards. From an anthropological point of view it would be interesting to find out which facial features allow the preference of a shorter camera-to-subject distance and which allow the preference of a longer camera-to-subject distance.

An Introduction to Multivariate Curve Resolution-Alternating Least Squares: Spectrophotometric Study of the Acid-Base Equilibria of 8-Hydroxyquinoline-5-Sulfonic Acid

ERIC Educational Resources Information Center

Rodriguez-Rodriguez, Cristina; Amigo, Jose Manuel; Coello, Jordi; Maspoch, Santiago

2007-01-01

A spectrophotometric study of the acid-base equilibria of 8-hydroxyquinoline-5-sulfonic acid to describe the multivariate curve resolution-alternating least squares algorithm (MCR-ALS) is described. The algorithm provides a lot of information and hence is of great importance for the chemometrics research.

Modeling the Migration of Fluids in Subduction Zones

NASA Astrophysics Data System (ADS)

Wilson, C. R.; Spiegelman, M.; Van Keken, P. E.; Vrijmoed, J. C.; Hacker, B. R.

2011-12-01

system of mantle and fluid flow equations, introducing complex feedbacks between the rheology, temperature, permeability, strain rate and porosity. Using idealized subduction zone geometries we investigate the effects of this non-linearity and explore the sensitivity of fluid flow paths for a range of fluid flow parameters with emphasis on variability of the location of the volcanic arc with respect to flow paths. We also estimate the expected degrees of hydrous melting using a variety of wet-melting parameterizations (e.g., Katz et al, 2003, Kelley et al, 2010). The current models only include dehydration reactions but work continues on the next generation of models which will include both dehydration and hydration reactions as well as parameterized flux melting in a consistent reactive-flow framework.

Comparative study of inversion methods of three-dimensional NMR and sensitivity to fluids

NASA Astrophysics Data System (ADS)

Tan, Maojin; Wang, Peng; Mao, Keyu

2014-04-01

Three-dimensional nuclear magnetic resonance (3D NMR) logging can simultaneously measure transverse relaxation time (T2), longitudinal relaxation time (T1), and diffusion coefficient (D). These parameters can be used to distinguish fluids in the porous reservoirs. For 3D NMR logging, the relaxation mechanism and mathematical model, Fredholm equation, are introduced, and the inversion methods including Singular Value Decomposition (SVD), Butler-Reeds-Dawson (BRD), and Global Inversion (GI) methods are studied in detail, respectively. During one simulation test, multi-echo CPMG sequence activation is designed firstly, echo trains of the ideal fluid models are synthesized, then an inversion algorithm is carried on these synthetic echo trains, and finally T2-T1-D map is built. Futhermore, SVD, BRD, and GI methods are respectively applied into a same fluid model, and the computing speed and inversion accuracy are compared and analyzed. When the optimal inversion method and matrix dimention are applied, the inversion results are in good aggreement with the supposed fluid model, which indicates that the inversion method of 3D NMR is applieable for fluid typing of oil and gas reservoirs. Additionally, the forward modeling and inversion tests are made in oil-water and gas-water models, respectively, the sensitivity to the fluids in different magnetic field gradients is also examined in detail. The effect of magnetic gradient on fluid typing in 3D NMR logging is stuied and the optimal manetic gradient is choosen.

Spaces of ideal convergent sequences.

PubMed

Mursaleen, M; Sharma, Sunil K

2014-01-01

In the present paper, we introduce some sequence spaces using ideal convergence and Musielak-Orlicz function ℳ = (M(k)). We also examine some topological properties of the resulting sequence spaces.

SUPPORT OF MSA AND GS SHORT COURSES AND THE COMPANION REVIEWS VOLUMES

DOE Office of Scientific and Technical Information (OSTI.GOV)

J Alex Speer

2008-01-23

Report on two short courses: [1] Fluid-fluid Equilibria in the Crust: Petrology - Geochemistry - Economic potential. August 16-17, 2007 preceding the Goldschmidt Conference in Cologne, Germany) and [2] Paleoaltimetry: Geochemical And Thermodynamic Approaches. October 26-27, 2007 (preceding the GSA Annual Meeting in Denver, Colorado)

Eutectic equilibria in the quaternary system Fe-Cr-Mn-C

NASA Technical Reports Server (NTRS)

Nowotny, H.; Wayne, S.; Schuster, J. C.

1982-01-01

The constitution of the quaternary system, Fe-Cr-Mn-C and to a lesser extent of the quinary system, Fe-Cr-Mn-Al-C were examined for in situ composite alloy candidates. Multivariant eutectic compositions were determined from phase equilibria studies wherein M7C3 carbides (approximately 30% by volume) formed from the melt within gamma iron. An extended field of the hexagonal carbide, (Cr, Fe, Mn)7 C3, was found without undergoing transformation to the orthorhombic structure. Increasing stability for this carbide was found for higher ratios of Cr/Fe(+) Cr + Mn. Aluminum additions promoted a ferritic matrix while manganese favored the desired gamma austenitic matrix. In coexistence with the matrix phase, chromium enters preferentially the carbide phase while manganese distributes equally between the gamma matrix and the M7C3 carbide. The composition and lattice parameters of the carbide and matrix phases were determined to establish their respective stabilities.

Management of Inflammatory Fluid Collections and Walled-Off Pancreatic Necrosis.

PubMed

Shah, Apeksha; Denicola, Richard; Edirisuriya, Cynthia; Siddiqui, Ali A

2017-12-01

Pancreatic fluid collections are a frequent complication of acute pancreatitis. The revised Atlanta criterion classifies chronic fluid collections into pseudocysts and walled-off pancreatic necrosis (WON). Symptomatic PFCs require drainage options that include surgical, percutaneous, or endoscopic approaches. With the advent of newer and more advanced endoscopic tools and expertise, minimally invasive endoscopic drainage has now become the preferred approach. An endoscopic ultrasonography (EUS)-guided approach for pancreatic fluid collection drainage is now the preferred endoscopic approach. Both plastic stents and metal stents are efficacious and safe; however, metal stents may offer an advantage, especially in infected pseudocysts and in WON. Direct endoscopic necrosectomy is often required in WON. Lumen apposing metal stents allow for direct endoscopic necrosectomy and debridement through the stent lumen and are now preferred in these patients. Endoscopic retrograde cholangiopancreatography with pancreatic duct exploration should be performed concurrent to PFC drainage in patients with suspected PD disruption. PD disruption is associated with an increased severity of pancreatitis, an increased risk of recurrent attacks of pancreatitis and long-term complications, and a decreased rate of PFC resolution after drainage. Ideally, pancreatic ductal disruption should be bridged with endoscopic stenting.

Effect of solution non-ideality on erythrocyte volume regulation.

PubMed

Levin, R L; Cravalho, E G; Huggins, C E

1977-03-01

A non-ideal, hydrated, non-dilute pseudo-binary salt-protein-water solution model of the erythrocyte intracellular solution is presented to describe the osmotic behavior of human erythrocytes. Existing experimental activity data for salts and proteins in aqueous solutions are used to formulate van Laar type expressions for the solvent and solute activity coefficients. Reasonable estimates can therefore be made of the non-ideality of the erythrocyte intracellular solution over a wide range of osmolalities. Solution non-ideality is shown to affect significantly the degree of solute polarization within the erythrocyte intracellular solution during freezing. However, the non-ideality has very little effect upon the amount of water retained within erythrocytes cooled at sub-zero temperatures.

Media-portrayed idealized images, body shame, and appearance anxiety.

PubMed

Monro, Fiona; Huon, Gail

2005-07-01

This study was designed to determine the effects of media-portrayed idealized images on young women's body shame and appearance anxiety, and to establish whether the effects depend on advertisement type and on participant self-objectification. Participants were 39 female university students. Twenty-four magazine advertisements comprised 12 body-related and 12 non-body-related products, one half of each with, and the other one half without, idealized images. Preexposure and post exposure body shame and appearance anxiety measures were recorded. Appearance anxiety increased after viewing advertisements featuring idealized images. There was also a significant interaction between self-objectification level and idealized body (presence vs. absence). No differences emerged for body-related compared with non-body-related product advertisements. The only result for body shame was a main effect for time. Participants' body shame increased after exposure to idealized images, irrespective of advertisement type. Although our findings reveal that media-portrayed idealized images detrimentally affect the body image of young women, they highlight the individual differences in vulnerability and the different effects for different components of body image. These results are discussed in terms of their implications for the prevention and early intervention of body image and dieting-related disorders. ( Copyright 2005 by Wiley Periodicals, Inc

The eigenfrequency spectrum of linear magnetohydrodynamic perturbations in stationary equilibria: A variational principle

NASA Astrophysics Data System (ADS)

Andries, Jesse

2010-11-01

The frequencies of the normal modes of oscillation of linear magnetohydrodynamic perturbations of a stationary equilibrium are related to the stationary points of a quadratic functional over the Hilbert space of Lagrangian displacement vectors, which is subject to a constraint. In the absence of a background flow (or of a uniform flow), the relation reduces to the well-known Rayleigh-Ritz variational principle. In contrast to the existing variational principles for perturbations of stationary equilibria, the present treatment does neither impose additional symmetry restrictions on the equilibrium, nor does it involve the generalization to bilinear functionals instead of quadratic forms. This allows a more natural interpretation of the quadratic forms as energy functionals.

Coupling Ideality of Integrated Planar High-Q Microresonators

NASA Astrophysics Data System (ADS)

Pfeiffer, Martin H. P.; Liu, Junqiu; Geiselmann, Michael; Kippenberg, Tobias J.

2017-02-01

Chip-scale optical microresonators with integrated planar optical waveguides are useful building blocks for linear, nonlinear, and quantum-optical photonic devices alike. Loss reduction through improving fabrication processes results in several integrated microresonator platforms attaining quality (Q ) factors of several millions. Beyond the improvement of the quality factor, the ability to operate the microresonator with high coupling ideality in the overcoupled regime is of central importance. In this regime, the dominant source of loss constitutes the coupling to a single desired output channel, which is particularly important not only for quantum-optical applications such as the generation of squeezed light and correlated photon pairs but also for linear and nonlinear photonics. However, to date, the coupling ideality in integrated photonic microresonators is not well understood, in particular, design-dependent losses and their impact on the regime of high ideality. Here we investigate design-dependent parasitic losses described by the coupling ideality of the commonly employed microresonator design consisting of a microring-resonator waveguide side coupled to a straight bus waveguide, a system which is not properly described by the conventional input-output theory of open systems due to the presence of higher-order modes. By systematic characterization of multimode high-Q silicon nitride microresonator devices, we show that this design can suffer from low coupling ideality. By performing 3D simulations, we identify the coupling to higher-order bus waveguide modes as the dominant origin of parasitic losses which lead to the low coupling ideality. Using suitably designed bus waveguides, parasitic losses are mitigated with a nearly unity ideality and strong overcoupling (i.e., a ratio of external coupling to internal resonator loss rate >9 ) are demonstrated. Moreover, we find that different resonator modes can exchange power through the coupler, which, therefore

Charged perfect fluid tori in strong central gravitational and dipolar magnetic fields

NASA Astrophysics Data System (ADS)

Kovář, Jiří; Slaný, Petr; Cremaschini, Claudio; Stuchlík, Zdeněk; Karas, Vladimír; Trova, Audrey

2016-06-01

We study electrically charged perfect fluid toroidal structures encircling a spherically symmetric gravitating object with Schwarzschild spacetime geometry and endowed with a dipole magnetic field. The work represents a direct continuation of our previous general-relativistic studies of electrically charged fluid in the approximation of zero conductivity, which formed tori around a Reissner-Nordström black hole or a Schwarzschild black hole equipped with a test electric charge and immersed in an asymptotically uniform magnetic field. After a general introduction of the zero-conductivity charged fluid model, we discuss a variety of possible topologies of the toroidal fluid configurations. Along with the charged equatorial tori forming interesting coupled configurations, we demonstrate the existence of the off-equatorial tori, for which the dipole type of magnetic field seems to be necessary. We focus on orbiting structures with constant specific angular momentum and on those in permanent rigid rotation. We stress that the general analytical treatment developed in our previous works is enriched here by the integrated form of the pressure equations. To put our work into an astrophysical context, we identify the central object with an idealization of a nonrotating magnetic neutron star. Constraining ranges of its parameters and also parameters of the circling fluid, we discuss a possible relevance of the studied toroidal structures, presenting along with their topology also pressure, density, temperature and charge profiles.

Modeling of Fluid-Membrane Interaction in Cellular Microinjection Process

NASA Astrophysics Data System (ADS)

Karzar-Jeddi, Mehdi; Diaz, Jhon; Olgac, Nejat; Fan, Tai-Hsi

2009-11-01

Cellular microinjection is a well-accepted method to deliver matters such as sperm, nucleus, or macromolecules into biological cells. To improve the success rate of in vitro fertilization and to establish the ideal operating conditions for a novel computer controlled rotationally oscillating intracytoplasmic sperm injection (ICSI) technology, we investigate the fluid-membrane interactions in the ICSI procedure. The procedure consists of anchoring the oocyte (a developing egg) using a holding pipette, penetrating oocyte's zona pellucida (the outer membrane) and the oolemma (the plasma or inner membrane) using an injection micropipette, and finally to deliver sperm into the oocyte for fertilization. To predict the large deformation of the oocyte membranes up to the piercing of the oolemma and the motion of fluids across both membranes, the dynamic fluid-pipette-membrane interactions are formulated by the coupled Stokes' equations and the continuum membrane model based on Helfrich's energy theory. A boundary integral model is developed to simulate the transient membrane deformation and the local membrane stress induced by the longitudinal motion of the injection pipette. The model captures the essential features of the membranes shown on optical images of ICSI experiments, and is capable of suggesting the optimal deformation level of the oolemma to start the rotational oscillations for piercing into the oolemma.

Multi-Fluid Simulations of a Coupled Ionosphere-Magnetosphere System

NASA Astrophysics Data System (ADS)

Gombosi, T. I.; Glocer, A.; Toth, G.; Ridley, A. J.; Sokolov, I. V.; de Zeeuw, D. L.

2008-05-01

In the last decade we have developed the Space Weather Modeling Framework (SWMF) that efficiently couples together different models describing the interacting regions of the space environment. Many of these domain models (such as the global solar corona, the inner heliosphere or the global magnetosphere) are based on MHD and are represented by our multiphysics code, BATS-R-US. BATS-R-US can solve the equations of "standard" ideal MHD, but it can also go beyond this first approximation. It can solve resistive MHD, Hall MHD, semi-relativistic MHD (that keeps the displacement current), multispecies (different ion species have different continuity equations) and multifluid (all ion species have separate continuity, momentum and energy equations) MHD. Recently we added two-fluid Hall MHD (solving the electron and ion energy equations separately) and are working on an extended magnetohydrodynamics model with anisotropic pressures. Ionosheric outflow can be a significant contributor to the plasma population of the magnetosphere during active geomagnetic conditions. This talk will present preliminary results of our simulations when we couple a new field- aligned multi-fluid polar wind code to the Ionosphere Electrodynamics (IE), and Global Magnetosphere (GM) components of the SWMF. We use multi-species and multi-fluid MHD to track the resulting plasma composition in the magnetosphere.

Stability of DIII-D high-performance, negative central shear discharges

NASA Astrophysics Data System (ADS)

Hanson, J. M.; Berkery, J. W.; Bialek, J.; Clement, M.; Ferron, J. R.; Garofalo, A. M.; Holcomb, C. T.; La Haye, R. J.; Lanctot, M. J.; Luce, T. C.; Navratil, G. A.; Olofsson, K. E. J.; Strait, E. J.; Turco, F.; Turnbull, A. D.

2017-05-01

Tokamak plasma experiments on the DIII-D device (Luxon et al 2005 Fusion Sci. Tech. 48 807) demonstrate high-performance, negative central shear (NCS) equilibria with enhanced stability when the minimum safety factor {{q}\\text{min}} exceeds 2, qualitatively confirming theoretical predictions of favorable stability in the NCS regime. The discharges exhibit good confinement with an L-mode enhancement factor H 89  =  2.5, and are ultimately limited by the ideal-wall external kink stability boundary as predicted by ideal MHD theory, as long as tearing mode (TM) locking events, resistive wall modes (RWMs), and internal kink modes are properly avoided or controlled. Although the discharges exhibit rotating TMs, locking events are avoided as long as a threshold minimum safety factor value {{q}\\text{min}}>2 is maintained. Fast timescale magnetic feedback control ameliorates RWM activity, expanding the stable operating space and allowing access to {β\\text{N}} values approaching the ideal-wall limit. Quickly growing and rotating instabilities consistent with internal kink mode dynamics are encountered when the ideal-wall limit is reached. The RWM events largely occur between the no- and ideal-wall pressure limits predicted by ideal MHD. However, evaluating kinetic contributions to the RWM dispersion relation results in a prediction of passive stability in this regime due to high plasma rotation. In addition, the ideal MHD stability analysis predicts that the ideal-wall limit can be further increased to {β\\text{N}}>4 by broadening the current profile. This path toward improved stability has the potential advantage of being compatible with the bootstrap-dominated equilibria envisioned for advanced tokamak (AT) fusion reactors.

Non-ideal magnetohydrodynamics on a moving mesh

NASA Astrophysics Data System (ADS)

Marinacci, Federico; Vogelsberger, Mark; Kannan, Rahul; Mocz, Philip; Pakmor, Rüdiger; Springel, Volker

2018-05-01

In certain astrophysical systems, the commonly employed ideal magnetohydrodynamics (MHD) approximation breaks down. Here, we introduce novel explicit and implicit numerical schemes of ohmic resistivity terms in the moving-mesh code AREPO. We include these non-ideal terms for two MHD techniques: the Powell 8-wave formalism and a constrained transport scheme, which evolves the cell-centred magnetic vector potential. We test our implementation against problems of increasing complexity, such as one- and two-dimensional diffusion problems, and the evolution of progressive and stationary Alfvén waves. On these test problems, our implementation recovers the analytic solutions to second-order accuracy. As first applications, we investigate the tearing instability in magnetized plasmas and the gravitational collapse of a rotating magnetized gas cloud. In both systems, resistivity plays a key role. In the former case, it allows for the development of the tearing instability through reconnection of the magnetic field lines. In the latter, the adopted (constant) value of ohmic resistivity has an impact on both the gas distribution around the emerging protostar and the mass loading of magnetically driven outflows. Our new non-ideal MHD implementation opens up the possibility to study magneto-hydrodynamical systems on a moving mesh beyond the ideal MHD approximation.

A diffusion tensor imaging tractography algorithm based on Navier-Stokes fluid mechanics.

PubMed

Hageman, Nathan S; Toga, Arthur W; Narr, Katherine L; Shattuck, David W

2009-03-01

We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color images of the DTI dataset.

Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weening, R. H.

2012-06-15

In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport inmore » regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.« less

Evolution of metamorphic fluids in shear zones: The record from the emeralds of Habachtal, Tauern Window, Austria

NASA Astrophysics Data System (ADS)

Nwe, Y. Y.; Grundmann, G.

1990-11-01

Fluid inclusions in emeralds from the Habachtal, Central Tauern Window, have been studied by microthermometry. Results allow a detailed reconstruction of trapping history and evolution of the metamorphic fluids during the Middle Alpine Tauernkristallisation metamorphic event and some of the subsequent cooling period. Five different types of fluid inclusions, corresponding to at least five trapping periods, have been distinguished. In general, the earliest primary (type 1) inclusions, which occur as negative crystals or thin long tubes, are represented by low salinity ( < 10 wt. % NaCl equivalent) aqueous fluids with or without CO 2 with up to XCO 2 ≈ 0.04. Later primary type 2 inclusions are distinguished by different morphologies and distribution patterns. Lower salinity CO 2-free brines and CO 2-bearing denser inclusions with higher CO 2 contents (up to XCO 2 ≈ 0.11) are characteristic of this stage. The type 2 inclusions may also occur as pseudosecondary arrays. The effects of necking have been studied, and found to be considerable in the type 1 primary inclusions. This mechanism has occasionally resulted in the appearance of almost pure CO 2 fluids. The possibility of fluid immiscibility has been examined, and rejected, for the apparent "coexistence" of primary brine and CO 2-bearing inclusions. Instead, mixing of fluids which fluctuated between two different compositions is proposed. The fluctuation was probably due to the sequence of hydration reactions during the Tauernkristallisation. Maximum trapping pressures (3.6 kbar) obtained for stage 1 of the Tauernkristallisation are thought to represent a situation where sublithostatic fluid pressures exested in shear zones during the crystallisation period of many of the emerald cores and coexisting biotite and actinolite. Maximum fluid pressures of 7 kbar were obtained from the type 2 inclusions. This is similar to pressure estimates obtained from mineral equilibria. At least four phases of deformation are

Gingival crevicular fluid proteomes in health, gingivitis and chronic periodontitis.

PubMed

Huynh, A H S; Veith, P D; McGregor, N R; Adams, G G; Chen, D; Reynolds, E C; Ngo, L H; Darby, I B

2015-10-01

The aim of this study was to compare the proteome composition of gingival crevicular fluid obtained from healthy periodontium, gingivitis and chronic periodontitis affected sites. Owing to its site-specific nature, gingival crevicular fluid is ideal for studying biological processes that occur during periodontal health and disease progression. However, few studies have been conducted into the gingival crevicular fluid proteome due to the small volumes obtained. Fifteen males were chosen for each of three different groups, healthy periodontium, gingivitis and chronic periodontitis. They were categorized based on clinical measurements including probing depth, bleeding on probing, plaque index, radiographic bone level, modified gingival index and smoking status. Gingival crevicular fluid was collected from each patient, pooled into healthy, gingivitis and chronic periodontitis groups and their proteome analyzed by gel electrophoresis and liquid chromatography electrospray ionization ion trap tandem mass spectrometry. One hundred and twenty-one proteins in total were identified, and two-thirds of these were identified in all three conditions. Forty-two proteins were considered to have changed in abundance. Of note, cystatin B and cystatin S decreased in abundance from health to gingivitis and further in chronic periodontitis. Complement proteins demonstrated an increase from health to gingivitis followed by a decrease in chronic periodontitis. Immunoglobulins, keratin proteins, fibronectin, lactotransferrin precursor, 14-3-3 protein zeta/delta, neutrophil defensin 3 and alpha-actinin exhibited fluctuations in levels. The gingival crevicular fluid proteome in each clinical condition was different and its analysis may assist us in understanding periodontal pathogenesis. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sharp Truncation of an Electric Field: An Idealized Model that Warrants Caution

NASA Astrophysics Data System (ADS)

Tu, Hong; Zhu, Jiongming

2016-03-01

In physics, idealized models are often used to simplify complex situations. The motivation of the idealization is to make the real complex system tractable by adopting certain simplifications. In this treatment some unnecessary, negligible aspects are stripped away (so-called Aristotelian idealization), or some deliberate distortions are involved (so-called Galilean idealization). The most important principle in using an idealized model is to make sure that all the neglected aspects do not affect our analysis or result. Point charges, rigid bodies, simple pendulums, frictionless planes, and isolated systems are all frequently used idealized models. However, when they are applied to certain uncommon models, extra precautions should be taken. The possibilities and necessities of adopting the idealizations have to be considered carefully. Sometimes some factors neglected or ignored in the idealization could completely change the result, even make the treatment unphysical and conclusions unscientific.

Micropollutant and sludge characterization for modeling sorption equilibria.

PubMed

Barret, Maialen; Carrère, Hélène; Latrille, Eric; Wisniewski, Christelle; Patureau, Dominique

2010-02-01

The sorption of hydrophobic micropollutants in sludge is one of the major mechanisms which drive their fate within wastewater treatment systems. The objective of this study was to investigate the influence of both sludge and micropollutant characteristics on the equilibria of sorption to particles and to dissolved and colloidal matter (DCM). For this purpose, the equilibrium constants were measured for 13 polycyclic aromatic hydrocarbons, 5 polychlorobiphenyls and the nonylphenol, and five different sludge types encountered in treatment systems: a primary sludge, a secondary sludge, the same secondary sludge after thermal treatment, after anaerobic digestion, and after both treatments. After thermal treatment, no more sorption to DCM was observed. Anaerobic biological treatment was shown to enhance micropollutants sorption to particles and to DCM of one logarithmic unit, due to matter transformation. Partial least-squares linear regressions of sorption data as a function of micropollutant and sludge properties revealed that sludge physical and chemical characteristics were more influential than micropollutant characteristics. Two models were provided to predict the sorption of such micropollutants in any sludge. To our knowledge, this is the first time that a three-compartment approach is used to accurately model micropollutant sorption in sludge and to understand the driving mechanisms.

Conformational equilibria of light-activated rhodopsin in nanodiscs

PubMed Central

Van Eps, Ned; Caro, Lydia N.; Morizumi, Takefumi; Kusnetzow, Ana Karin; Szczepek, Michal; Hofmann, Klaus Peter; Bayburt, Timothy H.; Sligar, Stephen G.; Ernst, Oliver P.; Hubbell, Wayne L.

2017-01-01

Conformational equilibria of G-protein–coupled receptors (GPCRs) are intimately involved in intracellular signaling. Here conformational substates of the GPCR rhodopsin are investigated in micelles of dodecyl maltoside (DDM) and in phospholipid nanodiscs by monitoring the spatial positions of transmembrane helices 6 and 7 at the cytoplasmic surface using site-directed spin labeling and double electron–electron resonance spectroscopy. The photoactivated receptor in DDM is dominated by one conformation with weak pH dependence. In nanodiscs, however, an ensemble of pH-dependent conformational substates is observed, even at pH 6.0 where the MIIbH+ form defined by proton uptake and optical spectroscopic methods is reported to be the sole species present in native disk membranes. In nanodiscs, the ensemble of substates in the photoactivated receptor spontaneously decays to that characteristic of the inactive state with a lifetime of ∼16 min at 20 °C. Importantly, transducin binding to the activated receptor selects a subset of the ensemble in which multiple substates are apparently retained. The results indicate that in a native-like lipid environment rhodopsin activation is not analogous to a simple binary switch between two defined conformations, but the activated receptor is in equilibrium between multiple conformers that in principle could recognize different binding partners. PMID:28373559

Assessments of fluid friction factors for use in leak rate calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chivers, T.C.

1997-04-01

Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

Concise Review: Amniotic Fluid Stem Cells: The Known, the Unknown, and Potential Regenerative Medicine Applications.

PubMed

Loukogeorgakis, Stavros P; De Coppi, Paolo

2017-07-01

The amniotic fluid has been identified as an untapped source of cells with broad potential, which possess immunomodulatory properties and do not have the ethical and legal limitations of embryonic stem cells. CD117(c-Kit)+ cells selected from amniotic fluid have been shown to differentiate into cell lineages representing all three embryonic germ layers without generating tumors, making them ideal candidates for regenerative medicine applications. Moreover, their ability to engraft in injured organs and modulate immune and repair responses of host tissues, suggest that transplantation of such cells may be useful for the treatment of various degenerative and inflammatory diseases. Although significant questions remain regarding the origin, heterogeneous phenotype, and expansion potential of amniotic fluid stem cells, evidence to date supports their potential role as a valuable stem cell source for the field of regenerative medicine. Stem Cells 2017;35:1663-1673. © 2016 AlphaMed Press.

Ideal thermodynamic processes of oscillatory-flow regenerative engines will go to ideal stirling cycle?

NASA Astrophysics Data System (ADS)

Luo, Ercang

2012-06-01

This paper analyzes the thermodynamic cycle of oscillating-flow regenerative machines. Unlike the classical analysis of thermodynamic textbooks, the assumptions for pistons' movement limitations are not needed and only ideal flowing and heat transfer should be maintained in our present analysis. Under such simple assumptions, the meso-scale thermodynamic cycles of each gas parcel in typical locations of a regenerator are analyzed. It is observed that the gas parcels in the regenerator undergo Lorentz cycle in different temperature levels, whereas the locus of all gas parcels inside the regenerator is the Ericson-like thermodynamic cycle. Based on this new finding, the author argued that ideal oscillating-flow machines without heat transfer and flowing losses is not the Stirling cycle. However, this new thermodynamic cycle can still achieve the same efficiency of the Carnot heat engine and can be considered a new reversible thermodynamic cycle under two constant-temperature heat sinks.

Moral Identity as Moral Ideal Self: Links to Adolescent Outcomes

ERIC Educational Resources Information Center

Hardy, Sam A.; Walker, Lawrence J.; Olsen, Joseph A.; Woodbury, Ryan D.; Hickman, Jacob R.

2014-01-01

The purposes of this study were to conceptualize moral identity as moral ideal self, to develop a measure of this construct, to test for age and gender differences, to examine links between moral ideal self and adolescent outcomes, and to assess purpose and social responsibility as mediators of the relations between moral ideal self and outcomes.…

Densimetry for the Quantification of Sorption Phenomena on Nonporous Media Near the Dew Point of Fluid Mixtures.

PubMed

Richter, Markus; McLinden, Mark O

2017-07-21

Phase equilibria of fluid mixtures are important in numerous industrial applications and are, thus, a major focus of thermophysical property research. Improved data, particularly along the dew line, are needed to improve model predictions. Here we present experimental results utilizing highly accurate densimetry to quantify the effects of sorption and capillary condensation, which exert a distorting influence on measured properties near the dew line. We investigate the (pressure, density, temperature, composition) behaviour of binary (CH 4  + C 3 H 8 ) and (Ar + CO 2 ) mixtures over the temperature range from (248.15 to 273.15) K starting at low pressures and increasing in pressure towards the dew point along isotherms. Three distinct regions are observed: (1) minor sorption effects in micropores at low pressures; (2) capillary condensation followed by wetting in macro-scale surface scratches beginning approximately 2% below the dew-point pressure; (3) bulk condensation. We hypothesize that the true dew point lies within the second region.

The effect of sediments on turbulent plume dynamics in a stratified fluid

NASA Astrophysics Data System (ADS)

Stenberg, Erik; Ezhova, Ekaterina; Brandt, Luca

2017-11-01

We report large eddy simulation results of sediment-loaded turbulent plumes in a stratified fluid. The configuration, where the plume is discharged from a round source, provides an idealized model of subglacial discharge from a submarine tidewater glacier and is a starting point for understanding the effect of sediments on the dynamics of the rising plume. The transport of sediments is modeled by means of an advection-diffusion equation where sediment settling velocity is taken into account. We initially follow the experimental setup of Sutherland (Phys. Rev. Fluids, 2016), considering uniformly stratified ambients and further extend the work to pycnocline-type stratifications typical of Greenland fjords. Apart from examining the rise height, radial spread and intrusion of the rising plume, we gain further insights of the plume dynamics by extracting turbulent characteristics and the distribution of the sediments inside the plume.

Jung's Red Book and its relation to aspects of German idealism.

PubMed

Bishop, Paul

2012-06-01

The late nineteenth century saw a renaissance of interest in the thought of the German Romantic philosopher, F.W.J. Schelling. This paper takes Jung's engagement with Schelling and his awareness of Schellingian ideas and interests (notably, the mysterious Kabeiroi worshipped at Samothrace) as its starting-point. It goes on to argue that a key set of problematics in German Idealism - the relation between freedom and necessity, between science and art, and ultimately between realism and idealism - offers a useful conceptual framework within which to approach Jung's Red Book. For the problem of the ideal is central to this work, which can be read as a journey from eternal ideals to the ideal of eternity. (Although the term 'idealism' has at least four distinct meanings, their distinct senses can be related in different ways to Jung's thinking.) The eloquent embrace of idealism by F.T. Vischer in a novel, Auch Einer, for which Jung had the highest praise, reminds us of the persistence of this tradition, which is still contested and debated in the present day. © 2012, The Society of Analytical Psychology.

A Generalized Deduction of the Ideal-Solution Model

ERIC Educational Resources Information Center

Leo, Teresa J.; Perez-del-Notario, Pedro; Raso, Miguel A.

2006-01-01

A new general procedure for deriving the Gibbs energy of mixing is developed through general thermodynamic considerations, and the ideal-solution model is obtained as a special particular case of the general one. The deduction of the Gibbs energy of mixing for the ideal-solution model is a rational one and viewed suitable for advanced students who…

MHD Stability of Axisymmetric Plasmas In Closed Line Magnetic Fields

NASA Astrophysics Data System (ADS)

Simakov, Andrei N.; Catto, Peter J.; Ramos, Jesus J.; Hastie, R. J.

2003-04-01

The stability of axisymmetric plasmas confined by closed poloidal magnetic field lines is considered. The results are relevant to plasmas in the dipolar fields of stars and planets, as well as the Levitated Dipole Experiment, multipoles, Z pinches and field reversed configurations. The ideal MHD energy principle is employed to study stability of pressure driven Alfvén modes. A point dipole is considered in detail to demonstrate that equilibria exist, which are MHD stable for arbitrary beta. Effects of sound waves and plasma resistivity are investigated next for point dipole equilibria by means of resistive MHD theory.

PARALLEL ASSAY OF OXYGEN EQUILIBRIA OF HEMOGLOBIN

PubMed Central

Lilly, Laura E.; Blinebry, Sara K.; Viscardi, Chelsea M.; Perez, Luis; Bonaventura, Joe; McMahon, Tim J.

2013-01-01

Methods to systematically analyze in parallel the function of multiple protein or cell samples in vivo or ex vivo (i.e. functional proteomics) in a controlled gaseous environment have thus far been limited. Here we describe an apparatus and procedure that enables, for the first time, parallel assay of oxygen equilibria in multiple samples. Using this apparatus, numerous simultaneous oxygen equilibrium curves (OECs) can be obtained under truly identical conditions from blood cell samples or purified hemoglobins (Hbs). We suggest that the ability to obtain these parallel datasets under identical conditions can be of immense value, both to biomedical researchers and clinicians who wish to monitor blood health, and to physiologists studying non-human organisms and the effects of climate change on these organisms. Parallel monitoring techniques are essential in order to better understand the functions of critical cellular proteins. The procedure can be applied to human studies, wherein an OEC can be analyzed in light of an individual’s entire genome. Here, we analyzed intraerythrocytic Hb, a protein that operates at the organism’s environmental interface and then comes into close contact with virtually all of the organism’s cells. The apparatus is theoretically scalable, and establishes a functional proteomic screen that can be correlated with genomic information on the same individuals. This new method is expected to accelerate our general understanding of protein function, an increasingly challenging objective as advances in proteomic and genomic throughput outpace the ability to study proteins’ functional properties. PMID:23827235

Media-portrayed idealized images, self-objectification, and eating behavior.

PubMed

Monro, Fiona J; Huon, Gail F

2006-11-01

This study examined the effects of media-portrayed idealized images on young women's eating behavior. The study compared the effects for high and low self-objectifiers. 72 female university students participated in this experiment. Six magazine advertisements featuring idealized female models were used as the experimental stimuli, and the same six advertisements with the idealized body digitally removed became the control stimuli. Eating behavior was examined using a classic taste test that involved both sweet and savory food. Participants' restraint status was assessed. We found that total food intake after exposure was the same in the body present and absent conditions. There were also no differences between high and low self-objectifiers' total food intake. However, for the total amount of food consumed and for sweet food there were significant group by condition interaction effects. High self-objectifiers ate more food in the body present than the body absent condition. In contrast, low self-objectifiers ate more food in the body absent than in the body present condition. Restraint status was not found to moderate the relationship between exposure to idealized images the amount of food consumed. Our results indicate that exposure to media-portrayed idealized images can lead to changes in eating behavior and highlight the complexity of the association between idealized image exposure and eating behavior. These results are discussed in terms of their implications for the prevention of dieting-related disorders.

Quasi-Equilibria of the Rotunno-Emanuel Tropical Cyclone Model

NASA Technical Reports Server (NTRS)

Chao, Winston C.; Chen, Baode

2003-01-01

Long-term integrations using the Rotunno-Emanuel (RE) model demonstrate that given sufficient elapsed time the weak initial vortex specified by R E can also lead to tropical cyclogenesis, albeit at a slower growth rate. Thus the RE notion of the finite-amplitude nature of tropical cyclogenesis is valid only if the period of examination is limited to the first eight days. These results also show that, if initial vortex as specified by RE is used, prior to cyclogenesis the model state does not resemble the observed pre-genesis disturbances in the sense that there is no precipitation in the center of the disturbance. Another experiment using the same model but with the initial vortex replaced by a disturbance with a different structure shows that a state resembling the observed pre-genesis disturbances can be simulated and this state can lead to spontaneous cyclogenesis, a rapid transition between two quasi-equilibria. This spontaneous cyclogenesis is associated with the generation of a new convective region at large radius and its subsequent contraction, which reminds one of the observed eye-wall replacement, but the distinction from the latter is obvious.

Simple fundamental equation of state for liquid, gas, and fluid of argon, nitrogen, and carbon dioxide

NASA Astrophysics Data System (ADS)

Kaplun, A. B.; Meshalkin, A. B.

2017-07-01

A new fundamental low-parametric equation of state in the form of reduced Helmholtz function for describing thermodynamic properties of normal substances was obtained using the methods and approaches developed earlier by the authors. It allows us to describe the thermal properties of gas, liquid, and fluid in the range from the density in ideal-gas state to the density at a triple point (except the critical region) with sufficiently high accuracy close to the accuracy of experiment. The caloric properties and sound velocity of argon, nitrogen, and carbon dioxide are calculated without involving any caloric data, except the ideal gas enthalpy. The obtained values of isochoric heat capacity, sound velocity, and other thermodynamic properties are in good agreement with experimental (reliable tabular) data.

Fluid mechanics in fluids at rest.

PubMed

Brenner, Howard

2012-07-01

Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.

Partitioning of F and Cl Between Apatite and a Synthetic Shergottite Liquid (QUE 94201) at 4 Gpa from 1300 TO 1500 C

NASA Technical Reports Server (NTRS)

McCubbin, F. M.; Barnes, J. J.; Vander Kaaden, K. E.; Boyce, J. W.

2017-01-01

Apatite [Ca5(PO4)3(F,Cl,OH)] is present in a wide range of planetary materials. Due to the presence of volatiles within its crystal structure (Xsite), many recent studies have attempted to use apatite to constrain the volatile contents of planetary magmas and mantle sources. In order to use the volatile contents of apatite to accurately determine the abundances of volatiles in coexisting silicate melt or fluids, thermodynamic models for the apatite solid solution and for the apatite components in multicomponent silicate melts and fluids are required. Although some thermodynamic models for apatite have been developed, they are incomplete. Furthermore, no mixing model is available for all of the apatite components in silicate melts or fluids, especially for F and Cl components. Several experimental studies have investigated the apatite-melt and apatite-fluid partitioning behavior of F, Cl, and OH in terrestrial and planetary systems, which have determined that apatite-melt partitioning of volatiles are best described as exchange equilibria similar to Fe-Mg partitioning between olivine and silicate melt. However, McCubbin et al., recently reported that the exchange coefficients vary in portions of apatite compositional space where F, Cl, and OH do not mix ideally in apatite. In particular, solution calorimetry data of apatite compositions along the F-Cl join exhibit substantial excess enthalpies of mixing, and McCubbin et al. reported substantial deviations in the Cl-F exchange Kd along the F-Cl apatite join that could be explained by the preferential incorporation of F into apatite. In the present study, we assess the effect of apatite crystal chemistry on F-Cl exchange equilibria between apatite and melt at 4 GPa over the temperature range of 1300-1500 C. The goal of these experiments is to assess the variation in the Ap-melt Cl-F exchange Kd over a broad range of F:Cl ratios in apatite. The results of these experiments could be used to understand at what

Four-fluid MHD simulations of the plasma and neutral gas environment of comet 67P/Churyumov-Gerasimenko near perihelion

NASA Astrophysics Data System (ADS)

Huang, Zhenguang; Tóth, Gábor; Gombosi, Tamas I.; Jia, Xianzhe; Rubin, Martin; Fougere, Nicolas; Tenishev, Valeriy; Combi, Michael R.; Bieler, Andre; Hansen, Kenneth C.; Shou, Yinsi; Altwegg, Kathrin

2016-05-01

The neutral and plasma environment is critical in understanding the interaction of the solar wind and comet 67P/Churyumov-Gerasimenko (CG), the target of the European Space Agency's Rosetta mission. To serve this need and support the Rosetta mission, we have developed a 3-D four-fluid model, which is based on BATS-R-US (Block-Adaptive Tree Solarwind Roe-type Upwind Scheme) within SWMF (Space Weather Modeling Framework) that solves the governing multifluid MHD equations and the Euler equations for the neutral gas fluid. These equations describe the behavior and interactions of the cometary heavy ions, the solar wind protons, the electrons, and the neutrals. This model incorporates different mass loading processes, including photoionization and electron impact ionization, charge exchange, dissociative ion-electron recombination, and collisional interactions between different fluids. We simulated the plasma and neutral gas environment near perihelion in three different cases: an idealized comet with a spherical body and uniform neutral gas outflow, an idealized comet with a spherical body and illumination-driven neutral gas outflow, and comet CG with a realistic shape model and illumination-driven neutral gas outflow. We compared the results of the three cases and showed that the simulations with illumination-driven neutral gas outflow have magnetic reconnection, a magnetic pileup region and nucleus directed plasma flow inside the nightside reconnection region, which have not been reported in the literature.

Diffusion of Supercritical Fluids through Single-Layer Nanoporous Solids: Theory and Molecular Simulations.

PubMed

Oulebsir, Fouad; Vermorel, Romain; Galliero, Guillaume

2018-01-16

With the advent of graphene material, membranes based on single-layer nanoporous solids appear as promising devices for fluid separation, be it liquid or gaseous mixtures. The design of such architectured porous materials would greatly benefit from accurate models that can predict their transport and separation properties. More specifically, there is no universal understanding of how parameters such as temperature, fluid loading conditions, or the ratio of the pore size to the fluid molecular diameter influence the permeation process. In this study, we address the problem of pure supercritical fluids diffusing through simplified models of single-layer porous materials. Basically, we investigate a toy model that consists of a single-layer lattice of Lennard-Jones interaction sites with a slit gap of controllable width. We performed extensive equilibrium and biased molecular dynamics simulations to document the physical mechanisms involved at the molecular scale. We propose a general constitutive equation for the diffusional transport coefficient derived from classical statistical mechanics and kinetic theory, which can be further simplified in the ideal gas limit. This transport coefficient relates the molecular flux to the fluid density jump across the single-layer membrane. It is found to be proportional to the accessible surface porosity of the single-layer porous solid and to a thermodynamic factor accounting for the inhomogeneity of the fluid close to the pore entrance. Both quantities directly depend on the potential of mean force that results from molecular interactions between solid and fluid atoms. Comparisons with the simulations data show that the kinetic model captures how narrowing the pore size below the fluid molecular diameter lowers dramatically the value of the transport coefficient. Furthermore, we demonstrate that our general constitutive equation allows for a consistent interpretation of the intricate effects of temperature and fluid loading

Ideal Cardiovascular Health and Arterial Stiffness in Spanish Adults-The EVIDENT Study.

PubMed

García-Hermoso, Antonio; Martínez-Vizcaíno, Vicente; Gomez-Marcos, Manuel Ángel; Cavero-Redondo, Iván; Recio-Rodriguez, José Ignacio; García-Ortiz, Luis

2018-05-01

Studies concerning ideal cardiovascular (CV) health and its relationship with arterial stiffness are lacking. This study examined the association between arterial stiffness with ideal CV health as defined by the American Heart Association, across age groups and gender. The cross-sectional study included 1365 adults. Ideal CV health was defined as meeting ideal levels of the following components: 4 behaviors (smoking, body mass index, physical activity, and Mediterranean diet adherence) and 3 factors (total cholesterol, blood pressure, and glycated hemoglobin). Patients were grouped into 3 categories according to their number of ideal CV health metrics: ideal (5-7 metrics), intermediate (3-4 metrics), and poor (0-2 metrics). We analyzed the pulse wave velocity (PWV), the central and radial augmentation indexes, and the ambulatory arterial stiffness index (AASI). The ideal CV health profile was inversely associated with lower arterial radial augmentation index and AASI in both genders, particularly in middle-aged (45-65 years) and in elderly subjects (>65 years). Also in elderly subjects, adjusted models showed that adults with at least 3 health metrics at ideal levels had significantly lower PWV than those with 2 or fewer ideal health metrics. An association was found between a favorable level of ideal CV health metrics and lower arterial stiffness across age groups. Copyright © 2018 National Stroke Association. Published by Elsevier Inc. All rights reserved.