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Sample records for nonlinearity vanishes coarsening

  1. Algebraic coarsening methods for linear and nonlinear PDE and systems

    International Nuclear Information System (INIS)

    McWilliams, J C

    2000-01-01

    In [l] Brandt describes a general approach for algebraic coarsening. Given fine-grid equations and a prescribed relaxation method, an approach is presented for defining both the coarse-grid variables and the coarse-grid equations corresponding to these variables. Although, these two tasks are not necessarily related (and, indeed, are often performed independently and with distinct techniques) in the approaches of [1] both revolve around the same underlying observation. To determine whether a given set of coarse-grid variables is appropriate it is suggested that one should employ compatible relaxation. This is a generalization of so-called F-relaxation (e.g., [2]). Suppose that the coarse-grid variables are defined as a subset of the fine-grid variables. Then, F-relaxation simply means relaxing only the F-variables (i.e., fine-grid variables that do not correspond to coarse-grid variables), while leaving the remaining fine-grid variables (C-variables) unchanged. The generalization of compatible relaxation is in allowing the coarse-grid variables to be defined differently, say as linear combinations of fine-grid variables, or even nondeterministically (see examples in [1]). For the present summary it suffices to consider the simple case. The central observation regarding the set of coarse-grid variables is the following [1]: Observation 1--A general measure for the quality of the set of coarse-grid variables is the convergence rate of compatible relaxation. The conclusion is that a necessary condition for efficient multigrid solution (e.g., with convergence rates independent of problem size) is that the compatible-relaxation convergence be bounded away from 1, independently of the number of variables. This is often a sufficient condition, provided that the coarse-grid equations are sufficiently accurate. Therefore, it is suggested in [1] that the convergence rate of compatible relaxation should be used as a criterion for choosing and evaluating the set of coarse

  2. Wave instabilities in nonlinear Schrödinger systems with non vanishing background

    KAUST Repository

    Trillo, Stefano; Gongora, J. S. Totero; Fratalocchi, Andrea

    2014-01-01

    We investigate wave collapse in the generalized nonlinear Schrödinger (NLS) equation and in the presence of a non vanishing background. Through the use of virial identities, we establish a new criterion for blow-up.

  3. Remarks on a Class of Nonlinear Schrödinger Equations with Potential Vanishing at Infinity

    Directory of Open Access Journals (Sweden)

    Hongbo Zhu

    2013-01-01

    Full Text Available We study the following nonlinear Schrödinger equation −Δu+V(xu=K(xf(u,  x∈ℝN,  u∈H1(ℝN, where the potential V(x vanishes at infinity. Working in weighted Sobolev space, we obtain the ground states of problem ( under a Nahari type condition. Furthermore, if V(x,K(x are radically symmetric with respect to x∈ℝN, it is shown that problem ( has a positive solution with some more general growth conditions of the nonlinearity. Particularly, if f(u=up, then the growth restriction σ≤p≤N+2/N-2 in Ambrosetti et al. (2005 can be relaxed to σ~≤p≤N+2/N-2, where σ~<σ if 0<β<α<2.

  4. Wave instabilities in the presence of non vanishing background in nonlinear Schrödinger systems

    KAUST Repository

    Trillo, S.; Gongora, J. S. Totero; Fratalocchi, Andrea

    2014-01-01

    We investigate wave collapse ruled by the generalized nonlinear Schrödinger (NLS) equation in 1+1 dimensions, for localized excitations with non-zero background, establishing through virial identities a new criterion for blow-up. When collapse

  5. Wave instabilities in the presence of non vanishing background in nonlinear Schrödinger systems

    KAUST Repository

    Trillo, S.

    2014-12-03

    We investigate wave collapse ruled by the generalized nonlinear Schrödinger (NLS) equation in 1+1 dimensions, for localized excitations with non-zero background, establishing through virial identities a new criterion for blow-up. When collapse is arrested, a semiclassical approach allows us to show that the system can favor the formation of dispersive shock waves. The general findings are illustrated with a model of interest to both classical and quantum physics (cubic-quintic NLS equation), demonstrating a radically novel scenario of instability, where solitons identify a marginal condition between blow-up and occurrence of shock waves, triggered by arbitrarily small mass perturbations of different sign.

  6. A general vanishing theorem

    Indian Academy of Sciences (India)

    Abstract. Let E be a vector bundle and L be a line bundle over a smooth projective variety X. In this article, we give a condition for the vanishing of Dolbeault cohomology groups of the form H p,q when Sα+β E ⊗ L is ample. This condition is shown to be invariant under the interchange of p and q. The optimality of.

  7. Vanishing in Plain Sight

    Directory of Open Access Journals (Sweden)

    Williams, Grace Alexandra

    2014-12-01

    Full Text Available Playfully negotiating the historical constructs of theatrical vanishing and its disturbingly female trappings this paper centers on the creation of Bautier de Kolta’s l’Escamotage D’une Dame, an illusion used to screen the anxieties of the male British populous, irked by a buoyant surplus in unmarried, white, middle class women, in the late 1880s. Introducing texts such as W. R Greg’s Why are women Redundant? This paper makes ever more apparent the political, violent and sexual connotations of the female body in magical feats of performative disappearance. From the photographic curios of hidden mothers to the dark room of the séance, the conversation unfurls around the many forms of female vanishing, culminating in a discussion of the contemporary artwork Escamotage (Grace A Williams, 2015 that takes the Persian rug as both a motif of magical vanishing and a tool for the exposure of form. This paper was originally delivered as a performance from within a ‘Zig-Zag’ illusion box, in collaboration with artist David Cheeseman. The first critical analysis of women’s role within magical illusions, delivered by a female artist from within a magical prop that continues to dismember female bodies for entertainment in the contemporary magic market.

  8. Heat exchanges in coarsening systems

    Energy Technology Data Exchange (ETDEWEB)

    Corberi, Federico [Dipartimento di Fisica ' E R Caianiello' , Università di Salerno, via Ponte don Melillo, 84084 Fisciano (Italy); Gonnella, Giuseppe; Piscitelli, Antonio [Dipartimento di Fisica, Università di Bari and Istituto Nazionale di Fisica Nucleare, Sezione di Bari, via Amendola 173, 70126 Bari (Italy)

    2011-10-15

    This paper is a contribution to the understanding of the thermal properties of ageing systems where statistically independent degrees of freedom with greatly separated time scales are expected to coexist. Focusing on the prototypical case of quenched ferromagnets, where fast and slow modes can be respectively associated with fluctuations in the bulk of the coarsening domains and in their interfaces, we perform a set of numerical experiments specifically designed to compute the heat exchanges between different degrees of freedom. Our studies promote a scenario with fast modes acting as an equilibrium reservoir to which interfaces may release heat through a mechanism that allows fast and slow degrees to maintain their statistical properties independently.

  9. Sequential models for coarsening and missingness

    NARCIS (Netherlands)

    Gill, R.D.; Robins, J.M.

    1997-01-01

    In a companion paper we described what intuitively would seem to be the most general possible way to generate Coarsening at Random mechanisms a sequential procedure called randomized monotone coarsening Counterexamples showed that CAR mechanisms exist which cannot be represented in this way Here we

  10. The vanishing volume of D = 4 superspace

    Energy Technology Data Exchange (ETDEWEB)

    Bossard, Guillaume, E-mail: bossard@cpht.polytechnique.f [Ecole Polytechnique (CNRS), Palaiseau Cedex (France). Centre de Physique Theorique; Howe, P.S., E-mail: paul.howe@kcl.ac.u [University of London (United Kingdom). King' s College. Dept. of Mathematics; Stelle, K.S., E-mail: stelle@imperial.ac.u [Imperial College London (United Kingdom). Theoretical Physics Group; Vanhove, Pierre, E-mail: pierre.vanhove@cea.f [University of California, Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics

    2011-07-01

    The volume of on-shell D = 4, N = 8 superspace is shown to vanish. Despite this, it is shown that there is a fully supersymmetric and duality-invariant candidate {nabla}{sup 8}R{sup 4} counterterm corresponding to an anticipated seven-loop logarithmic divergence in D = 4. We construct this counterterm explicitly and also give the complete nonlinear extension of the 1=8-BPS {nabla}{sup 6}R{sup 4} invariant. Similar results are derived for N = 4; 5 and 6. (author)

  11. PETN Coarsening - Predictions from Accelerated Aging Data

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Amitesh [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gee, Richard H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-03-30

    Ensuring good ignition properties over long periods of time necessitates maintaining a good level of porosity in powders of initiator materials and preventing particle coarsening. To simulate porosity changes of such powder materials over long periods of time a common strategy is to perform accelerated aging experiments over shorter time spans at elevated temperatures. In this paper we examine historical accelerated-aging data on powders of Pentaerythritol Tetranitrate (PETN), an important energetic material, and make predictions for long-term aging under ambient conditions. Lastly, we develop an evaporation-condensation- based model to provide some mechanistic understanding of the coarsening process.

  12. Structural refinement and coarsening in deformed metals

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Xing, Q.

    2005-01-01

    The microstructural refinement by plastic deformation is analysed in terms of key parameters, the spacing between and the misorientation angle across the boundaries subdividing the structure. Coarsening of such structures by annealing is also characterised. For both deformed and annealed structur...

  13. Mangghuer Embroidery: A Vanishing Tradition

    OpenAIRE

    Aila Pullinen

    2015-01-01

    Aila Pullinen. 2015. Mangghuer Embroidery: A Vanishing Tradition IN Gerald Roche and CK Stuart (eds) Asian Highlands Perspectives 36: Mapping the Monguor, 178-188, 301-332. Visits were undertaken in the years 2001 and 2002 to Minhe Hui and Mangghuer (Tu) Autonomous County, Haidong Municipality, Qinghai Province, China to research and document Mangghuer embroidery. This research is summarized in terms of the history of Mangghuer embroidery, tools and materials, embroidery techniques, embr...

  14. Shape and coarsening dynamics of strained islands

    DEFF Research Database (Denmark)

    Schifani, Guido; Frisch, Thomas; Argentina, Mederic

    2016-01-01

    and numerically the formation of an equilibrium island using a two-dimensional continuous model. We have found that these equilibrium island-like solutions have a maximum height h_{0} and they sit on top of a flat wetting layer with a thickness h_{w}. We then consider two islands, and we report that they undergo...... and leads to the shrinkage of the smallest island. Once its height becomes smaller than a minimal equilibrium height h_{0}^{*}, its mass spreads over the entire system. Our results pave the way for a future analysis of coarsening of an assembly of islands....

  15. Tight closure and vanishing theorems

    International Nuclear Information System (INIS)

    Smith, K.E.

    2001-01-01

    Tight closure has become a thriving branch of commutative algebra since it was first introduced by Mel Hochster and Craig Huneke in 1986. Over the past few years, it has become increasingly clear that tight closure has deep connections with complex algebraic geometry as well, especially with those areas of algebraic geometry where vanishing theorems play a starring role. The purpose of these lectures is to introduce tight closure and to explain some of these connections with algebraic geometry. Tight closure is basically a technique for harnessing the power of the Frobenius map. The use of the Frobenius map to prove theorems about complex algebraic varieties is a familiar technique in algebraic geometry, so it should perhaps come as no surprise that tight closure is applicable to algebraic geometry. On the other hand, it seems that so far we are only seeing the tip of a large and very beautiful iceberg in terms of tight closure's interpretation and applications to algebraic geometry. Interestingly, although tight closure is a 'characteristic p' tool, many of the problems where tight closure has proved useful have also yielded to analytic (L2) techniques. Despite some striking parallels, there had been no specific result directly linking tight closure and L∼ techniques. Recently, however, the equivalence of an ideal central to the theory of tight closure was shown to be equivalent to a certain 'multiplier ideal' first defined using L2 methods. Presumably, deeper connections will continue to emerge. There are two main types of problems for which tight closure has been helpful: in identifying nice structure and in establishing uniform behavior. The original algebraic applications of tight closure include, for example, a quick proof of the Hochster-Roberts theorem on the Cohen-Macaulayness of rings of invariants, and also a refined version of the Brianqon-Skoda theorem on the uniform behaviour of integral closures of powers of ideals. More recent, geometric

  16. Grain coarsening in polymineralic contact metamorphic carbonate rocks: The role of different physical interactions during coarsening

    DEFF Research Database (Denmark)

    Brodhag, Sabine; Herwegh, Marco; Berger, Alfons

    2011-01-01

    ) and microstructures with considerable second-phase volume fractions of up to 0.5. The variations might be of general validity for any polymineralic rock, which undergoes grain coarsening during metamorphism. The new findings are important for a better understanding of the initiation of strain localization based...... on the activation of grain size dependent deformation mechanisms....

  17. Hydrography-driven coarsening of grid digital elevation models

    Science.gov (United States)

    Moretti, G.; Orlandini, S.

    2017-12-01

    A new grid coarsening strategy, denoted as hydrography-driven (HD) coarsening, is developed in the present study. The HD coarsening strategy is designed to retain the essential hydrographic features of surface flow paths observed in high-resolution digital elevation models (DEMs): (1) depressions are filled in the considered high-resolution DEM, (2) the obtained topographic data are used to extract a reference grid network composed of all surface flow paths, (3) the Horton order is assigned to each link of the reference grid network, and (4) within each coarse grid cell, the elevation of the point lying along the highest-order path of the reference grid network and displaying the minimum distance to the cell center is assigned to this coarse grid cell center. The capabilities of the HD coarsening strategy to provide consistent surface flow paths with respect to those observed in high-resolution DEMs are evaluated over a synthetic valley and two real drainage basins located in the Italian Alps and in the Italian Apennines. The HD coarsening is found to yield significantly more accurate surface flow path profiles than the standard nearest neighbor (NN) coarsening. In addition, the proposed strategy is found to reduce drastically the impact of depression-filling procedures in coarsened topographic data. The HD coarsening strategy is therefore advocated for all those cases in which the relief of the extracted drainage network is an important hydrographic feature. The figure below reports DEMs of a synthetic valley and extracted surface flow paths. (a) 10-m grid DEM displaying no depressions and extracted surface flow path (gray line). (b) 1-km grid DEM obtained from NN coarsening. (c) 1-km grid DEM obtained from NN coarsening plus depression-filling and extracted surface flow path (light blue line). (d) 1-km grid DEM obtained from HD coarsening and extracted surface flow path (magenta line).

  18. Metrics with vanishing quantum corrections

    International Nuclear Information System (INIS)

    Coley, A A; Hervik, S; Gibbons, G W; Pope, C N

    2008-01-01

    We investigate solutions of the classical Einstein or supergravity equations that solve any set of quantum corrected Einstein equations in which the Einstein tensor plus a multiple of the metric is equated to a symmetric conserved tensor T μν (g αβ , ∂ τ g αβ , ∂ τ ∂ σ g αβ , ...,) constructed from sums of terms, the involving contractions of the metric and powers of arbitrary covariant derivatives of the curvature tensor. A classical solution, such as an Einstein metric, is called universal if, when evaluated on that Einstein metric, T μν is a multiple of the metric. A Ricci flat classical solution is called strongly universal if, when evaluated on that Ricci flat metric, T μν vanishes. It is well known that pp-waves in four spacetime dimensions are strongly universal. We focus attention on a natural generalization; Einstein metrics with holonomy Sim(n - 2) in which all scalar invariants are zero or constant. In four dimensions we demonstrate that the generalized Ghanam-Thompson metric is weakly universal and that the Goldberg-Kerr metric is strongly universal; indeed, we show that universality extends to all four-dimensional Sim(2) Einstein metrics. We also discuss generalizations to higher dimensions

  19. Coarsening dynamics in the Vicsek model

    Science.gov (United States)

    Dey, Supravat; Katyal, Nisha; Das, Dibyendu; Puri, Sanjay

    We numerically study the flocking model introduced by Vicsek et al. (1995) in the coarsening regime. At standard self-propulsion speeds, we find two distinct growth laws for the coupled density and velocity fields. The characteristic length scale of the density domains grows as Lρ (t) t 1 / 4 , while the velocity length scale grows much faster, viz . , Lv (t) t 5 / 6 . The spatial fluctuations in the density and velocity ordering are studied by calculating the two-point correlation function and the structure factor, which show deviations from the well-known Porod's law. This is a natural consequence of scattering from irregular morphologies that dynamically arise in the system. In contrast, at lower self-propulsion speeds, the morphology is distinct, and as a result a new set of scaling exponents emerge. Most strikingly, the velocity order follows the density order with Lρ (t) Lv (t) t 1 / 4 .

  20. Semi-coarsening multigrid methods for parallel computing

    Energy Technology Data Exchange (ETDEWEB)

    Jones, J.E.

    1996-12-31

    Standard multigrid methods are not well suited for problems with anisotropic coefficients which can occur, for example, on grids that are stretched to resolve a boundary layer. There are several different modifications of the standard multigrid algorithm that yield efficient methods for anisotropic problems. In the paper, we investigate the parallel performance of these multigrid algorithms. Multigrid algorithms which work well for anisotropic problems are based on line relaxation and/or semi-coarsening. In semi-coarsening multigrid algorithms a grid is coarsened in only one of the coordinate directions unlike standard or full-coarsening multigrid algorithms where a grid is coarsened in each of the coordinate directions. When both semi-coarsening and line relaxation are used, the resulting multigrid algorithm is robust and automatic in that it requires no knowledge of the nature of the anisotropy. This is the basic multigrid algorithm whose parallel performance we investigate in the paper. The algorithm is currently being implemented on an IBM SP2 and its performance is being analyzed. In addition to looking at the parallel performance of the basic semi-coarsening algorithm, we present algorithmic modifications with potentially better parallel efficiency. One modification reduces the amount of computational work done in relaxation at the expense of using multiple coarse grids. This modification is also being implemented with the aim of comparing its performance to that of the basic semi-coarsening algorithm.

  1. The vanishing discount problem and viscosity Mather measures. Part 2: boundary value problems

    OpenAIRE

    Ishii, Hitoshi; Mitake, Hiroyoshi; Tran, Hung V.

    2016-01-01

    In arXiv:1603.01051 (Part 1 of this series), we have introduced a variational approach to studying the vanishing discount problem for fully nonlinear, degenerate elliptic, partial differential equations in a torus. We develop this approach further here to handle boundary value problems. In particular, we establish new representation formulas for solutions of discount problems, critical values, and use them to prove convergence results for the vanishing discount problems.

  2. ERROR DISTRIBUTION EVALUATION OF THE THIRD VANISHING POINT BASED ON RANDOM STATISTICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    C. Li

    2012-07-01

    Full Text Available POS, integrated by GPS / INS (Inertial Navigation Systems, has allowed rapid and accurate determination of position and attitude of remote sensing equipment for MMS (Mobile Mapping Systems. However, not only does INS have system error, but also it is very expensive. Therefore, in this paper error distributions of vanishing points are studied and tested in order to substitute INS for MMS in some special land-based scene, such as ground façade where usually only two vanishing points can be detected. Thus, the traditional calibration approach based on three orthogonal vanishing points is being challenged. In this article, firstly, the line clusters, which parallel to each others in object space and correspond to the vanishing points, are detected based on RANSAC (Random Sample Consensus and parallelism geometric constraint. Secondly, condition adjustment with parameters is utilized to estimate nonlinear error equations of two vanishing points (VX, VY. How to set initial weights for the adjustment solution of single image vanishing points is presented. Solving vanishing points and estimating their error distributions base on iteration method with variable weights, co-factor matrix and error ellipse theory. Thirdly, under the condition of known error ellipses of two vanishing points (VX, VY and on the basis of the triangle geometric relationship of three vanishing points, the error distribution of the third vanishing point (VZ is calculated and evaluated by random statistical simulation with ignoring camera distortion. Moreover, Monte Carlo methods utilized for random statistical estimation are presented. Finally, experimental results of vanishing points coordinate and their error distributions are shown and analyzed.

  3. Error Distribution Evaluation of the Third Vanishing Point Based on Random Statistical Simulation

    Science.gov (United States)

    Li, C.

    2012-07-01

    POS, integrated by GPS / INS (Inertial Navigation Systems), has allowed rapid and accurate determination of position and attitude of remote sensing equipment for MMS (Mobile Mapping Systems). However, not only does INS have system error, but also it is very expensive. Therefore, in this paper error distributions of vanishing points are studied and tested in order to substitute INS for MMS in some special land-based scene, such as ground façade where usually only two vanishing points can be detected. Thus, the traditional calibration approach based on three orthogonal vanishing points is being challenged. In this article, firstly, the line clusters, which parallel to each others in object space and correspond to the vanishing points, are detected based on RANSAC (Random Sample Consensus) and parallelism geometric constraint. Secondly, condition adjustment with parameters is utilized to estimate nonlinear error equations of two vanishing points (VX, VY). How to set initial weights for the adjustment solution of single image vanishing points is presented. Solving vanishing points and estimating their error distributions base on iteration method with variable weights, co-factor matrix and error ellipse theory. Thirdly, under the condition of known error ellipses of two vanishing points (VX, VY) and on the basis of the triangle geometric relationship of three vanishing points, the error distribution of the third vanishing point (VZ) is calculated and evaluated by random statistical simulation with ignoring camera distortion. Moreover, Monte Carlo methods utilized for random statistical estimation are presented. Finally, experimental results of vanishing points coordinate and their error distributions are shown and analyzed.

  4. Observation of changing crystal orientations during grain coarsening

    International Nuclear Information System (INIS)

    Sharma, Hemant; Huizenga, Richard M.; Bytchkov, Aleksei; Sietsma, Jilt; Offerman, S. Erik

    2012-01-01

    Understanding the underlying mechanisms of grain coarsening is important in controlling the properties of metals, which strongly depend on the microstructure that forms during the production process or during use at high temperature. Grain coarsening of austenite at 1273 K in a binary Fe–2 wt.% Mn alloy was studied using synchrotron radiation. Evolution of the volume, average crystallographic orientation and mosaicity of more than 2000 individual austenite grains was tracked during annealing. It was found that an approximately linear relationship exists between grain size and mosaicity, which means that orientation gradients are present in the grains. The orientation gradients remain constant during coarsening and consequently the character of grain boundaries changes during coarsening, affecting the coarsening rate. Furthermore, changes in the average orientation of grains during coarsening were observed. The changes could be understood by taking the observed orientation gradients and anisotropic movement of grain boundaries into account. Five basic modes of grain coarsening were deduced from the measurements, which include: anisotropic (I) and isotropic (II) growth (or shrinkage); movement of grain boundaries resulting in no change in volume but a change in shape (III); movement of grain boundaries resulting in no change in volume and mosaicity, but a change in crystallographic orientation (IV); no movement of grain boundaries (V).

  5. Phase field modeling of dendritic coarsening during isothermal

    Directory of Open Access Journals (Sweden)

    Zhang Yutuo

    2011-08-01

    Full Text Available Dendritic coarsening in Al-2mol%Si alloy during isothermal solidification at 880K was investigated by phase field modeling. Three coarsening mechanisms operate in the alloy: (a melting of small dendrite arms; (b coalescence of dendrites near the tips leading to the entrapment of liquid droplets; (c smoothing of dendrites. Dendrite melting is found to be dominant in the stage of dendritic growth, whereas coalescence of dendrites and smoothing of dendrites are dominant during isothermal holding. The simulated results provide a better understanding of dendrite coarsening during isothermal solidification.

  6. Finite element analysis of mechanical stability of coarsened nanoporous gold

    International Nuclear Information System (INIS)

    Cho, Hoon-Hwe; Chen-Wiegart, Yu-chen Karen; Dunand, David C.

    2016-01-01

    The mechanical stability of nanoporous gold (np-Au) at various stages of thermal coarsening is studied via finite element analysis under volumetric compression using np-Au architectures imaged via X-ray nano-tomography. As the np-Au is coarsened thermally over ligament sizes ranging from 185 to 465 nm, the pore volume fraction is determinant for the mechanical stability of the coarsened np-Au, unlike the curvature and surface orientation of the ligaments. The computed Young's modulus and yield strength of the structures are compared with the Gibson–Ashby model. The geometry of the structures determines the locations where stress concentrations occur at the onset of yielding.

  7. A novel coarsening mechanism of droplets in immiscible fluid mixtures

    Science.gov (United States)

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-06-01

    In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with inter-droplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian-coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of individual droplets, causing accidental collisions and subsequent interface-tension-driven coalescence. Contrary to this, here we demonstrate that the droplet motion is not random, but hydrodynamically driven by the composition Marangoni force due to an interfacial tension gradient produced in each droplet as a consequence of composition correlation among droplets. This alters our physical understanding of droplet coarsening in immiscible liquid mixtures on a fundamental level.

  8. On vanishing of vacuum energy for superstrings

    International Nuclear Information System (INIS)

    Morozov, A.; Perelomov, A.

    1986-01-01

    Hypothesis, concerning the structure of formulae for vacuum diagrams in the first-quantized superstring theory is proposed. The analytical measure in the integration over moduli space is proportional to the sum over spin structures on Riemann surfaces and vanishes because of the Riemann identities for Θ-constants

  9. Natural occupation numbers: When do they vanish?

    NARCIS (Netherlands)

    Giesbertz, K.J.H.; Van Leeuwen, R.

    The non-vanishing of the natural orbital (NO) occupation numbers of the one-particle density matrix of many-body systems has important consequences for the existence of a density matrix-potential mapping for nonlocal potentials in reduced density matrix functional theory and for the validity of the

  10. Leukoencephalopathy With Vanishing White Matter: A Review

    NARCIS (Netherlands)

    Bugiani, M.; Boor, I.; Powers, J.M.; Scheper, G.C.; van der Knaap, M.S.

    2010-01-01

    Vanishing white matter (VWM) is one of the most prevalent inherited childhood leukoencephalopathies, but this may affect people ofall ages, including neonates and adults. It is a progressive disorder clinically dominated by cerebellar ataxia and in which minor stress conditions, such as fever or

  11. Leukoencephalopathy with vanishing white matter: a review

    NARCIS (Netherlands)

    Bugiani, Marianna; Boor, Ilja; Powers, James M.; Scheper, Gert C.; van der Knaap, Marjo S.

    2010-01-01

    Vanishing white matter (VWM) is one of the most prevalent inherited childhood leukoencephalopathies, but this may affect people of all ages, including neonates and adults. It is a progressive disorder clinically dominated by cerebellar ataxia and in which minor stress conditions, such as fever or

  12. Structure and grain coarsening during the processing of engineering ceramics

    International Nuclear Information System (INIS)

    Shaw, N.J.

    1987-11-01

    Studies have been made of three ceramic systems (Al 2 O 3 , Y 2 O 3 /MgO, and SiC/C/B), both to explore a surface area/density diagram approach to examining the coarsening processes during sintering and to explore an alternative coarsening parameter, i.e., the grain boundary surface area (raising it at a given value of the density) and not the pore surface area; therefore, pinning of the grain boundaries by solid-solution drag is the only function evidenced by these results. The importance of such pinning even at densities as low as 75% of theoretical is linked to the existence of microstructural inhomogeneities. The early stages of sintering of Y 2 O 3 powder have been examined using two techniques, BET surface area analysis and transmission electron microscopy. Each has given some insight into the process occurring and, used together, have provided some indication of the effect of MgO on coarsening during sintering. Attempts to further elucidate effects of MgO on the coarsening behavior of Y 2 O 3 by the surface area/density diagram approach were unsuccessful due to masking effects of contaminating reactions during sintering and/or thermal etching. The behavior of the undoped SiC which only coarsens can be clearly distinguished by the surface area/density diagram from that of SiC/C/B which also concurrently densifies. Little additional information was obtainable by this method due to unfavorable sample etching characteristics. The advantages, disadvantages, and difficulties of application of these techniques to the study of coarsening during sintering are discussed

  13. Coarsening by network restructuring in model nanoporous gold

    International Nuclear Information System (INIS)

    Kolluri, Kedarnath; Demkowicz, Michael J.

    2011-01-01

    Using atomistic modeling, we show that restructuring of the network of interconnected ligaments causes coarsening in a model of nanoporous gold. The restructuring arises from the collapse of some ligaments onto neighboring ones and is enabled by localized plasticity at ligaments and nodes. This mechanism may explain the occurrence of enclosed voids and reduction in volume in nanoporous metals during their synthesis. An expression is developed for the critical ligament radius below which coarsening by network restructuring may occur spontaneously, setting a lower limit to the ligament dimensions of nanofoams.

  14. On the monoaxial stabilization of a rigid body under vanishing restoring torque

    Science.gov (United States)

    Aleksandrov, A. Yu.; Aleksandrova, E. B.; Tikhonov, A. A.

    2018-05-01

    The problem of monoaxial stabilization of a rigid body is studied. It is assumed that a linear time-invariant dissipative torque and a time-varying restoring torque vanishing as time increases act on the body. Both the case of linear restoring torque and that of essentially nonlinear one are considered. With the aid of the decomposition method, conditions are obtained under which we can guarantee the asymptotic stability of an equilibrium position of the body despite the vanishing of the restoring torque. A numerical simulation is provided to demonstrate the effectiveness of our theoretical results.

  15. Coupling between drainage and coarsening in wet foam

    Indian Academy of Sciences (India)

    Abstract. Drainage and coarsening are two coupled phenomena during the evolution of wet foam. We show the variation in the growth rate of bubble size, along the height in a column of Gillette shaving foam, by microscope imaging. Simultaneously, the drainage of liquid at the same heights has been investigated by ...

  16. Coarsening dynamics in a vibrofluidized compartmentalized granulas gas

    NARCIS (Netherlands)

    van der Meer, Roger M.; van der Weele, J.P.; Lohse, Detlef

    2004-01-01

    Coarsening is studied in a vertically driven, initially uniformly distributed granular gas within a container divided into many connected compartments. The clustering is experimentally observed to occur in a two-stage process: first, the particles cluster in a few of the compartments. Subsequently,

  17. Coarsening of Faraday Heaps: Experiment, Simulation, and Theory

    NARCIS (Netherlands)

    Gerner, van H.J.; Robledo, Caballero G.A.; Meer, van der D.; Weele, van der J.P.; Hoef, van der M.A.

    2009-01-01

    When a layer of granular material is vertically shaken, the surface spontaneously breaks up in a landscape of small Faraday heaps that merge into larger ones on an ever increasing time scale. This coarsening process is studied in a linear setup, for which the average life span of the transient state

  18. Moose models with vanishing S parameter

    International Nuclear Information System (INIS)

    Casalbuoni, R.; De Curtis, S.; Dominici, D.

    2004-01-01

    In the linear moose framework, which naturally emerges in deconstruction models, we show that there is a unique solution for the vanishing of the S parameter at the lowest order in the weak interactions. We consider an effective gauge theory based on K SU(2) gauge groups, K+1 chiral fields, and electroweak groups SU(2) L and U(1) Y at the ends of the chain of the moose. S vanishes when a link in the moose chain is cut. As a consequence one has to introduce a dynamical nonlocal field connecting the two ends of the moose. Then the model acquires an additional custodial symmetry which protects this result. We examine also the possibility of a strong suppression of S through an exponential behavior of the link couplings as suggested by the Randall Sundrum metric

  19. Vanishing cosmological constant in elementary particles theory

    International Nuclear Information System (INIS)

    Pisano, F.; Tonasse, M.D.

    1997-01-01

    The quest of a vanishing cosmological constant is considered in the simplest anomaly-free chiral gauge extension of the electroweak standard model where the new physics is limited to a well defined additional flavordynamics above the Fermi scale, namely up to a few TeVs by matching the gauge coupling constants at the electroweak scale, and with an extended Higgs structure. In contrast to the electroweak standard model, it is shown how the extended scalar sector of the theory allows a vanishing or a very small cosmological constant. the details of the cancellation mechanism are presented. At accessible energies the theory is indistinguishable from the standard model of elementary particles and it is in agreement with all existing data. (author). 32 refs

  20. Foam flow in a model porous medium: I. The effect of foam coarsening.

    Science.gov (United States)

    Jones, S A; Getrouw, N; Vincent-Bonnieu, S

    2018-05-09

    Foam structure evolves with time due to gas diffusion between bubbles (coarsening). In a bulk foam, coarsening behaviour is well defined, but there is less understanding of coarsening in confined geometries such as porous media. Previous predictions suggest that coarsening will cause foam lamellae to move to low energy configurations in the pore throats, resulting in greater capillary resistance when restarting flow. Foam coarsening experiments were conducted in both a model-porous-media micromodel and in a sandstone core. In both cases, foam was generated by coinjecting surfactant solution and nitrogen. Once steady state flow had been achieved, the injection was stopped and the system sealed off. In the micromodel, the foam coarsening was recorded using time-lapse photography. In the core flood, the additional driving pressure required to reinitiate flow after coarsening was measured. In the micromodel the bubbles coarsened rapidly to the pore size. At the completion of coarsening the lamellae were located in minimum energy configurations in the pore throats. The wall effect meant that the coarsening did not conform to the unconstricted growth laws. The coreflood tests also showed coarsening to be a rapid process. The additional driving pressure to restart flow reached a maximum after just 2 minutes.

  1. Neutrino mass matrices with vanishing determinant

    International Nuclear Information System (INIS)

    Chauhan, Bhag C.; Pulido, Joao; Picariello, Marco

    2006-01-01

    We investigate the prospects for neutrinoless double beta decay, texture zeros. and equalities between neutrino mass matrix elements in scenarios with vanishing determinant mass matrices for vanishing and finite θ 13 mixing angles in normal and inverse mass hierarchies. For normal hierarchy and both zero and finite θ 13 it is found that neutrinoless double beta decay cannot be observed by any of the present or next generation experiments, while for inverse hierarchy it is, on the contrary, accessible to experiments. Regarding texture zeros and equalities between mass matrix elements, we find that in both normal and inverse hierarchies with θ 13 =0 no texture zeros nor any such equalities can exist apart from the obvious ones. For θ 13 ≠0 some texture zeros become possible. In normal hierarchy two texture zeros occur if 8.1x10 -2 ≤sinθ 13 ≤9.1x10 -2 while in inverse hierarchy three are possible, one with sinθ 13 ≥7x10 -3 and two others with sinθ 13 ≥0.18. All equalities between mass matrix elements are impossible with θ 13 ≠0

  2. The story of antimatter matter's vanished twin

    CERN Document Server

    Borissov, Guennadi

    2018-01-01

    Each elementary particle contained within every known substance has an almost identical twin called its antiparticle. Existing data clearly indicate that equal numbers of particles and antiparticles were initially created soon after the birth of the universe. Despite this, all objects around us, as well as all the stars in all the known galaxies, are made of particles, while antiparticles have almost completely vanished. The reasons behind this disappearance are not yet fully known. Uncovering them will allow us to not only penetrate much deeper into the structure of matter, but also to understand the secret mechanisms that determine the genesis and development of our immense universe. That is why explaining the mystery of the missing antimatter is currently considered to be one of the main tasks of particle physics. This book tells the story of all the achievements in solving the problem of the missing antiparticles including the latest developments in the field. It is written by Prof. Guennadi Borissov, an...

  3. Electromagnetic fields with vanishing quantum corrections

    Science.gov (United States)

    Ortaggio, Marcello; Pravda, Vojtěch

    2018-04-01

    We show that a large class of null electromagnetic fields are immune to any modifications of Maxwell's equations in the form of arbitrary powers and derivatives of the field strength. These are thus exact solutions to virtually any generalized classical electrodynamics containing both non-linear terms and higher derivatives, including, e.g., non-linear electrodynamics as well as QED- and string-motivated effective theories. This result holds not only in a flat or (anti-)de Sitter background, but also in a larger subset of Kundt spacetimes, which allow for the presence of aligned gravitational waves and pure radiation.

  4. Vanishing "tattoo" multisensor for biomedical diagnostics

    Science.gov (United States)

    Moczko, E.; Meglinski, I.; Piletsky, S.

    2008-02-01

    Currently, precise non-invasive diagnostics systems for the real-time multi detection and monitoring of physiological parameters and chemical analytes in the human body are urgently required by clinicians, physiologists and bio-medical researchers. We have developed a novel cost effective smart 'vanishing tattoo' (similar to temporary child's tattoos) consisting of environmental-sensitive dyes. Painlessly impregnated into the skin the smart tattoo is capable of generating optical/fluorescence changes (absorbance, transmission, reflectance, emission and/or luminescence within UV, VIS or NIR regions) in response to physical or chemical changes. These changes allow the identification of colour pattern changes similar to bar-code scanning. Such a system allows an easy, cheap and robust comprehensive detection of various parameters and analytes in a small volume of sample (e.g. variations in pH, temperature, ionic strength, solvent polarity, presence of redox species, surfactants, oxygen). These smart tattoos have possible applications in monitoring the progress of disease and transcutaneous drug delivery. The potential of this highly innovative diagnostic tool is wide and diverse and can impact on routine clinical diagnostics, general therapeutic management, skin care and cosmetic products testing as well as fundamental physiological investigations.

  5. Microstructure taxonomy based on spatial correlations: Application to microstructure coarsening

    International Nuclear Information System (INIS)

    Fast, Tony; Wodo, Olga; Ganapathysubramanian, Baskar; Kalidindi, Surya R.

    2016-01-01

    To build materials knowledge, rigorous description of the material structure and associated tools to explore and exploit information encoded in the structure are needed. These enable recognition, categorization and identification of different classes of microstructure and ultimately enable to link structure with properties of materials. Particular interest lies in the protocols capable of mining the essential information in large microstructure datasets and building robust knowledge systems that can be easily accessed, searched, and shared by the broader materials community. In this paper, we develop a protocol based on automated tools to classify microstructure taxonomies in the context of coarsening behavior which is important for long term stability of materials. Our new concepts for enhanced description of the local microstructure state provide flexibility of description. The mathematical description of microstructure that capture crucial attributes of the material, although central to building materials knowledge, is still elusive. The new description captures important higher order spatial information, but at the same time, allows down sampling if less information is needed. We showcase the classification protocol by studying coarsening of binary polymer blends and classifying steady state structures. We study several microstructure descriptions by changing the microstructure local state order and discretization and critically evaluate their efficacy. Our analysis revealed the superior properties of microstructure representation is based on the first order-gradient of the atomic fraction.

  6. Ripple coarsening on ion beam-eroded surfaces.

    Science.gov (United States)

    Teichmann, Marc; Lorbeer, Jan; Frost, Frank; Rauschenbach, Bernd

    2014-01-01

    The temporal evolution of ripple pattern on Ge, Si, Al 2 O 3, and SiO 2 by low-energy ion beam erosion with Xe (+) ions is studied. The experiments focus on the ripple dynamics in a fluence range from 1.1 × 10(17) cm(-2) to 1.3 × 10(19) cm(-2) at ion incidence angles of 65° and 75° and ion energies of 600 and 1,200 eV. At low fluences a short-wavelength ripple structure emerges on the surface that is superimposed and later on dominated by long wavelength structures for increasing fluences. The coarsening of short wavelength ripples depends on the material system and angle of incidence. These observations are associated with the influence of reflected primary ions and gradient-dependent sputtering. The investigations reveal that coarsening of the pattern is a universal behavior for all investigated materials, just at the earliest accessible stage of surface evolution.

  7. Electromagnetic fields with vanishing quantum corrections

    Czech Academy of Sciences Publication Activity Database

    Ortaggio, Marcello; Pravda, Vojtěch

    2018-01-01

    Roč. 779, 10 April (2018), s. 393-395 ISSN 0370-2693 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : nonlinear electrodynamics * quantum corrections Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.807, year: 2016 https://www. science direct.com/ science /article/pii/S0370269318300327?via%3Dihub

  8. Electromagnetic fields with vanishing quantum corrections

    Czech Academy of Sciences Publication Activity Database

    Ortaggio, Marcello; Pravda, Vojtěch

    2018-01-01

    Roč. 779, 10 April (2018), s. 393-395 ISSN 0370-2693 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : nonlinear electrodynamics * quantum corrections Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.807, year: 2016 https://www.sciencedirect.com/science/article/pii/S0370269318300327?via%3Dihub

  9. Marginal regression analysis of recurrent events with coarsened censoring times.

    Science.gov (United States)

    Hu, X Joan; Rosychuk, Rhonda J

    2016-12-01

    Motivated by an ongoing pediatric mental health care (PMHC) study, this article presents weakly structured methods for analyzing doubly censored recurrent event data where only coarsened information on censoring is available. The study extracted administrative records of emergency department visits from provincial health administrative databases. The available information of each individual subject is limited to a subject-specific time window determined up to concealed data. To evaluate time-dependent effect of exposures, we adapt the local linear estimation with right censored survival times under the Cox regression model with time-varying coefficients (cf. Cai and Sun, Scandinavian Journal of Statistics 2003, 30, 93-111). We establish the pointwise consistency and asymptotic normality of the regression parameter estimator, and examine its performance by simulation. The PMHC study illustrates the proposed approach throughout the article. © 2016, The International Biometric Society.

  10. Composition pathway in Fe–Cu–Ni alloy during coarsening

    International Nuclear Information System (INIS)

    Mukherjee, Rajdip; Nestler, Britta; Choudhury, Abhik

    2013-01-01

    In this work the microstructure evolution for a two phase Fe–Cu–Ni ternary alloy is studied in order to understand the kinetic composition paths during coarsening of precipitates. We have employed a quantitative phase-field model utilizing the CALPHAD database to simulate the temporal evolution of a multi-particle system in a two-dimensional domain. The paths for the far-field matrix and for precipitate average compositions obtained from simulation are found to be rectilinear. The trends are compared with the corresponding sharp interface theory, in the context of an additional degree of freedom for determining the interface compositions due to the Gibbs–Thomson effect in a ternary alloy. (paper)

  11. Composition pathway in Fe-Cu-Ni alloy during coarsening

    Science.gov (United States)

    Mukherjee, Rajdip; Choudhury, Abhik; Nestler, Britta

    2013-10-01

    In this work the microstructure evolution for a two phase Fe-Cu-Ni ternary alloy is studied in order to understand the kinetic composition paths during coarsening of precipitates. We have employed a quantitative phase-field model utilizing the CALPHAD database to simulate the temporal evolution of a multi-particle system in a two-dimensional domain. The paths for the far-field matrix and for precipitate average compositions obtained from simulation are found to be rectilinear. The trends are compared with the corresponding sharp interface theory, in the context of an additional degree of freedom for determining the interface compositions due to the Gibbs-Thomson effect in a ternary alloy.

  12. Coarsening behaviours of coherent γ' and γ precipitates in elastically constrained Ni-Al-Ti alloys

    International Nuclear Information System (INIS)

    Maebashi, T.; Doi, M.

    2004-01-01

    The coarsening behaviours of γ' and γ precipitates in elastically constrained Ni-Al-Ti alloys were investigated by means of transmission electron microscopy. When the Ni-8 at.% Al-6 at.% Ti alloy is aged at 1023 K, coherent γ' particles having L1 2 structure appear and coarsen in the γ matrix having disordered A1 structure. At first the mean particle size increases in proportion to the cube root of ageing time t ( ∝ t 1/3 ), and then the coarsening remarkably decelerates. The shape of γ' precipitate changes from the sphere to the cube as the coarsening progresses. When the Ni-13 at.% Al-9 at.% Ti alloy is aged at 973 K, coherent γ particles appear and coarsen in the γ' matrix. At first the relation of ∝ t 1/3 holds good, and then the coarsening accelerates, so that the increases in proportion to the square root of t ( ∝ t 1/2 ). The shape of γ precipitate changes to the plate having {1 0 0} planes as the coarsening progresses. Such coarsening behaviours of γ' and γ precipitates are good examples of the elasticity effects in elastically constrained systems

  13. Degenerate nonlinear diffusion equations

    CERN Document Server

    Favini, Angelo

    2012-01-01

    The aim of these notes is to include in a uniform presentation style several topics related to the theory of degenerate nonlinear diffusion equations, treated in the mathematical framework of evolution equations with multivalued m-accretive operators in Hilbert spaces. The problems concern nonlinear parabolic equations involving two cases of degeneracy. More precisely, one case is due to the vanishing of the time derivative coefficient and the other is provided by the vanishing of the diffusion coefficient on subsets of positive measure of the domain. From the mathematical point of view the results presented in these notes can be considered as general results in the theory of degenerate nonlinear diffusion equations. However, this work does not seek to present an exhaustive study of degenerate diffusion equations, but rather to emphasize some rigorous and efficient techniques for approaching various problems involving degenerate nonlinear diffusion equations, such as well-posedness, periodic solutions, asympt...

  14. Coarsening dynamics of binary liquids with active rotation.

    Science.gov (United States)

    Sabrina, Syeda; Spellings, Matthew; Glotzer, Sharon C; Bishop, Kyle J M

    2015-11-21

    Active matter comprised of many self-driven units can exhibit emergent collective behaviors such as pattern formation and phase separation in both biological (e.g., mussel beds) and synthetic (e.g., colloidal swimmers) systems. While these behaviors are increasingly well understood for ensembles of linearly self-propelled "particles", less is known about the collective behaviors of active rotating particles where energy input at the particle level gives rise to rotational particle motion. A recent simulation study revealed that active rotation can induce phase separation in mixtures of counter-rotating particles in 2D. In contrast to that of linearly self-propelled particles, the phase separation of counter-rotating fluids is accompanied by steady convective flows that originate at the fluid-fluid interface. Here, we investigate the influence of these flows on the coarsening dynamics of actively rotating binary liquids using a phenomenological, hydrodynamic model that combines a Cahn-Hilliard equation for the fluid composition with a Navier-Stokes equation for the fluid velocity. The effect of active rotation is introduced though an additional force within the Navier-Stokes equations that arises due to gradients in the concentrations of clockwise and counter-clockwise rotating particles. Depending on the strength of active rotation and that of frictional interactions with the stationary surroundings, we observe and explain new dynamical behaviors such as "active coarsening" via self-generated flows as well as the emergence of self-propelled "vortex doublets". We confirm that many of the qualitative behaviors identified by the continuum model can also be found in discrete, particle-based simulations of actively rotating liquids. Our results highlight further opportunities for achieving complex dissipative structures in active materials subject to distributed actuation.

  15. Slow coarsening of B2-ordered domains at low temperatures: A kinetic Monte Carlo study

    International Nuclear Information System (INIS)

    Le Floc'h, D.; Bellon, P.; Athenes, M.

    2000-01-01

    The kinetics of the ordering and coarsening of B2-ordered domains is studied using atomistic kinetic Monte Carlo simulations. Special emphasis is put on the effect of annealing temperature, alloy composition, and atom dynamics on the coarsening behavior. When atomic diffusion proceeds by vacancy jumps to nearest-neighbor sites, a transient slow coarsening regime is observed at temperatures below half the order-disorder transition temperature T c . It results in apparent coarsening exponents that decrease with decreasing the annealing temperature. Values as low as 0.14 are measured at 0.25T c . Slow transients take place in both stoichiometric and nonstoichiometric alloys. These regimes are correlated with the transient creation of excess antisites during domain disappearance. Since antiphase boundary mobility decreases with increasing antisite concentration, this transient excess results in the slow coarsening observed in simulations. (c) 2000 The American Physical Society

  16. On Vanishing Two Loop Cosmological Constants in Nonsupersymmetric Strings

    Energy Technology Data Exchange (ETDEWEB)

    Kachru, S

    1998-10-22

    It has recently been suggested that in certain special nonsupersymmetric type II string compactifications, at least the first two perturbative contributions to the cosmological constant Lambda vanish. Support for perturbative vanishing beyond 1-loop (as well as evidence for the absence of some nonperturbative contributions) has come from duality arguments. There was also a direct 2-loop computation which was incomplete; in this note we explain the deficiency of the previous 2-loop calculation and discuss the complete 2-loop computation in two different models. The corrected analysis yields a vanishing 2-loop contribution to Lambda in these models.

  17. On vanishing two loop cosmological constants in nonsupersymmetric strings

    International Nuclear Information System (INIS)

    Kachru, Shamit; Silverstein, Eva

    1998-01-01

    It has recently been suggested that in certain special nonsupersymmetric type II string compactifications, at least the first two perturbative contributions to the cosmological constant Λ vanish. Support for perturbative vanishing beyond 1-loop (as well as evidence for the absence of some nonperturbative contributions) has come from duality arguments. There was also a direct 2-loop computation which was incomplete; in this note we explain the deficiency of the previous 2-loop calculation and discuss the complete 2-loop computation in two different models. The corrected analysis yields a vanishing 2-loop contribution to Λ in these models

  18. Multi-lane detection based on multiple vanishing points detection

    Science.gov (United States)

    Li, Chuanxiang; Nie, Yiming; Dai, Bin; Wu, Tao

    2015-03-01

    Lane detection plays a significant role in Advanced Driver Assistance Systems (ADAS) for intelligent vehicles. In this paper we present a multi-lane detection method based on multiple vanishing points detection. A new multi-lane model assumes that a single lane, which has two approximately parallel boundaries, may not parallel to others on road plane. Non-parallel lanes associate with different vanishing points. A biological plausibility model is used to detect multiple vanishing points and fit lane model. Experimental results show that the proposed method can detect both parallel lanes and non-parallel lanes.

  19. Relaxation and coarsening of weakly-interacting breathers in a simplified DNLS chain

    Science.gov (United States)

    Iubini, Stefano; Politi, Antonio; Politi, Paolo

    2017-07-01

    The discrete nonlinear Schrödinger (DNLS) equation displays a parameter region characterized by the presence of localized excitations (breathers). While their formation is well understood and it is expected that the asymptotic configuration comprises a single breather on top of a background, it is not clear why the dynamics of a multi-breather configuration is essentially frozen. In order to investigate this question, we introduce simple stochastic models, characterized by suitable conservation laws. We focus on the role of the coupling strength between localized excitations and background. In the DNLS model, higher breathers interact more weakly, as a result of their faster rotation. In our stochastic models, the strength of the coupling is controlled directly by an amplitude-dependent parameter. In the case of a power-law decrease, the associated coarsening process undergoes a slowing down if the decay rate is larger than a critical value. In the case of an exponential decrease, a freezing effect is observed that is reminiscent of the scenario observed in the DNLS. This last regime arises spontaneously when direct energy diffusion between breathers and background is blocked below a certain threshold.

  20. Genetics Home Reference: leukoencephalopathy with vanishing white matter

    Science.gov (United States)

    ... Torres C, Pröschel C. EIF2B5 mutations compromise GFAP+ astrocyte generation in vanishing white matter leukodystrophy. Nat Med. ... of Medicine Lister Hill National Center for Biomedical Communications 8600 Rockville Pike, Bethesda, MD 20894, USA HONCode ...

  1. vanishing bone disease in a tertiary teaching hospital in uganda

    African Journals Online (AJOL)

    prior to the above presentation and review of systems were unremarkable. General examination revealed a ... syndrome or disease, massive osteolysis, disappearing bone disease, vanishing bone disease, idiopathic ... patient symptoms and anatomic location. Medical treatment involves, radiation therapy, anti-osteoclastic.

  2. Coarsening kinetics of γ' precipitates in the Ni-Al-Mo system

    International Nuclear Information System (INIS)

    Wang Tao; Sheng Guang; Liu Zikui; Chen Longqing

    2008-01-01

    The effect of Mo on the microstructure evolution and coarsening kinetics of γ' precipitates in the Ni-Al-Mo system is studied using phase-field simulations with inputs from thermodynamic, kinetic and lattice parameter databases. For alloys of different compositions, the precipitate morphology and the statistical information of precipitate sizes are predicted as a function of annealing time. It is observed that increasing Mo content leads to a change of the precipitate morphology from being cuboidal to spherical as well as a reduction in the coarsening rate. Comparison between simulated results and existing experimental microstructure morphologies and coarsening rates shows good agreements

  3. Universal postquench coarsening and aging at a quantum critical point

    Science.gov (United States)

    Gagel, Pia; Orth, Peter P.; Schmalian, Jörg

    2015-09-01

    The nonequilibrium dynamics of a system that is located in the vicinity of a quantum critical point is affected by the critical slowing down of order-parameter correlations with the potential for novel out-of-equilibrium universality. After a quantum quench, i.e., a sudden change of a parameter in the Hamiltonian, such a system is expected to almost instantly fall out of equilibrium and undergo aging dynamics, i.e., dynamics that depends on the time passed since the quench. Investigating the quantum dynamics of an N -component φ4 model coupled to an external bath, we determine this universal aging and demonstrate that the system undergoes a coarsening, governed by a critical exponent that is unrelated to the equilibrium exponents of the system. We analyze this behavior in the large-N limit, which is complementary to our earlier renormalization-group analysis, allowing in particular the direct investigation of the order-parameter dynamics in the symmetry-broken phase and at the upper critical dimension. By connecting the long-time limit of fluctuations and response, we introduce a distribution function that shows that the system remains nonthermal and exhibits quantum coherence even on long time scales.

  4. Coarsening of stripe patterns: variations with quench depth and scaling.

    Science.gov (United States)

    Tripathi, Ashwani K; Kumar, Deepak

    2015-02-01

    The coarsening of stripe patterns when the system is evolved from random initial states is studied by varying the quench depth ε, which is a measure of distance from the transition point of the stripe phase. The dynamics of the growth of stripe order, which is characterized by two length scales, depends on the quench depth. The growth exponents of the two length scales vary continuously with ε. The decay exponents for free energy, stripe curvature, and densities of defects like grain boundaries and dislocations also show similar variation. This implies a breakdown of the standard picture of nonequilibrium dynamical scaling. In order to understand the variations with ε we propose an additional scaling with a length scale dependent on ε. The main contribution to this length scale comes from the "pinning potential," which is unique to systems where the order parameter is spatially periodic. The periodic order parameter gives rise to an ε-dependent potential, which can pin defects like grain boundaries, dislocations, etc. This additional scaling provides a compact description of variations of growth exponents with quench depth in terms of just one exponent for each of the length scales. The relaxation of free energy, stripe curvature, and the defect densities have also been related to these length scales. The study is done at zero temperature using Swift-Hohenberg equation in two dimensions.

  5. Defect dynamics and coarsening dynamics in smectic-C films

    Science.gov (United States)

    Pargellis, A. N.; Finn, P.; Goodby, J. W.; Panizza, P.; Yurke, B.; Cladis, P. E.

    1992-12-01

    We study the dynamics of defects generated in free-standing films of liquid crystals following a thermal quench from the smectic-A phase to the smectic-C phase. The defects are type-1 disclinations, and the strain field between defect pairs is confined to 2π walls. We compare our observations with a phenomenological model that includes dipole coupling of the director field to an external ordering field. This model is able to account for both the observed coalescence dynamics and the observed ordering dynamics. In the absence of an ordering field, our model predicts the defect density ρ to scale with time t as ρ lnρ~t-1. When the dipole coupling of the director field to an external ordering field is included, both the model and experiments show the defect coarsening proceeds as ρ~e-αt with the strain field confined to 2π walls. The external ordering field most likely arises from the director's tendency to align with edge dislocations within the liquid-crystal film.

  6. Coarsening-densification transition temperature in sintering of uranium dioxide

    International Nuclear Information System (INIS)

    Balakrishna, Palanki; Narasimha Murty, B.; Chakraborthy, K.P.; Jayaraj, R.N.; Ganguly, C.

    2001-01-01

    The concept of coarsening-densification transition temperature (CDTT) has been proposed to explain the experimental observations of the study of sintering undoped uranium dioxide and niobia-doped uranium dioxide powder compacts in argon atmosphere in a laboratory tubular furnace. The general method for deducing CDTT for a given material under the prevailing conditions of sintering and the likely variables that influence the CDTT are described. Though the present work is specific in nature for uranium dioxide sintering in argon atmosphere, the concept of CDTT is fairly general and must be applicable to sintering of any material and has immense potential to offer advantages in designing and/or optimizing the profile of a sintering furnace, in the diagnosis of the fault in the process conditions of sintering, and so on. The problems of viewing the effect of heating rate only in terms of densification are brought out in the light of observing the undesirable phenomena of coring and bloating and causes were identified and remedial measures suggested

  7. Coarsening of AA6013-T6 Precipitates During Sheet Warm Forming Applications

    Science.gov (United States)

    Di Ciano, M.; DiCecco, S.; Esmaeili, S.; Wells, M. A.; Worswick, M. J.

    2018-03-01

    The use of warm forming for AA6xxx-T6 sheet is of interest to improve its formability; however, the effect warm forming may have on the coarsening of precipitates and the mechanical strength of these sheets has not been well studied. In this research, the coarsening behavior of AA6013-T6 precipitates has been explored, in the temperature range of 200-300 °C, and time of 30 s up to 50 h. Additionally, the effect of warm deformation on coarsening behavior was explored using: (1) simulated warm forming tests in a Gleeble thermo-mechanical simulator and (2) bi-axial warm deformation tests. Using a strong obstacle model to describe the yield strength (YS) evolution of the AA6013-T6 material, and a Lifshitz, Slyozov, and Wagner (LSW) particle coarsening law to describe the change in precipitate size with time, the coarsening kinetics were modeled for this alloy. The coarsening kinetics in the range of 220-300 °C followed a trend similar to that previously found for AA6111 for the 180-220 °C range. There was strong evidence that coarsening kinetics were not altered due to warm deformation above 220 °C. For warm forming between 200 and 220 °C, the YS of the AA6013-T6 material increased slightly, which could be attributed to strain hardening during warm deformation. Finally, a non-isothermal coarsening model was used to assess the potential reduction in the YS of AA6013-T6 for practical processing conditions related to auto-body manufacturing. The model calculations showed that 90% of the original AA6013-T6 YS could be maintained, for warm forming temperatures up to 280 °C, if the heating schedule used to get the part to the warm forming temperature was limited to 1 min.

  8. Experimental investigation of particle size distribution influence on diffusion controlled coarsening

    International Nuclear Information System (INIS)

    Fang, Zhigang; Patterson, B.R.

    1993-01-01

    The influence of initial particle size distribution on coarsening during liquid phase sintering has been experimentally investigated using W-14Ni-6Fe alloy as a model system. It was found that initially wider size distribution particles coarsened more rapidly than those of an initially narrow distribution. The well known linear relationship between the cube of the average particle radius bar r -3 , and time was observed for most of the coarsening process, although the early stage coarsening rate constant changed with time, as expected with concomitant early changes in the tungsten particle size distribution. The instantaneous transient rate constant was shown to be related to the geometric standard deviation, 1nσ, of the instantaneous size distributions, with higher rate constants corresponding to larger 1nσ values. The form of the particle size distributions changed rapidly during early coarsening and reached a quasi-stable state, different from the theoretical asymptotic distribution, after some time. A linear relationship was found between the experimentally observed instantaneous rate constant and that computed from an earlier model incorporating the effect of particle size distribution. The above results compare favorably with those from prior theoretical modeling and computer simulation studies of the effect of particle size distribution on coarsening, based on the DeHoff communicating neighbor model

  9. Vanishing theorems and effective results in algebraic geometry

    International Nuclear Information System (INIS)

    Demailly, J.P.; Goettsche, L.; Lazarsfeld, R.

    2001-01-01

    The School on Vanishing Theorems and Effective Results in Algebraic Geometry took place in ICTP, Trieste from 25 April 2000 to 12 May 2000. It was organized by J. P. Demailly (Universite de Grenoble I) and R. Lazarsfeld (University of Michigan). The main topics considered were vanishing theorems, multiplyer ideal sheaves and effective results in algebraic geometry, tight closure, geometry of higher dimensional projective and Kahler manifolds, hyperbolic algebraic varieties. The school consisted of two weeks of lectures and one week of conference. This volume contains the lecture notes of most of the lectures in the first two weeks

  10. Exact penalty results for mathematical programs with vanishing constraints

    Czech Academy of Sciences Publication Activity Database

    Hoheisel, T.; Kanzow, Ch.; Outrata, Jiří

    2010-01-01

    Roč. 72, č. 5 (2010), s. 2514-2526 ISSN 0362-546X R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506 Keywords : Mathematical programs with vanishing constraints * Mathematical programs with equilibrium constraints * Exact penalization * Calmness * Subdifferential calculus * Limiting normal cone Subject RIV: BA - General Mathematics Impact factor: 1.279, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/outrata-exact penalty results for mathematical programs with vanishing constraints.pdf

  11. On the vanishing rate of smooth CR functions

    Directory of Open Access Journals (Sweden)

    Giuseppe Della Sala

    2014-01-01

    Full Text Available Let be a lineally convex hypersurface of ℂⁿ of finite type, 0∈. Then there exist non-trivial smooth CR functions on that are flat at 0, i.e. whose Taylor expansion about 0 vanishes identically. Our aim is to characterize the rate at which flat CR functions can decrease without vanishing identically. As it turns out, non-trivial CR functions cannot decay arbitrarily fast, and a possible way of expressing the critical rate is by comparison with a suitable exponential of the modulus of a local peak function.

  12. Vanishing theorems and effective results in algebraic geometry

    Energy Technology Data Exchange (ETDEWEB)

    Demailly, J P [Universite de Grenoble (France); Goettsche, L [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Lazarsfeld, R [University of Michigan (United States)

    2001-12-15

    The School on Vanishing Theorems and Effective Results in Algebraic Geometry took place in ICTP, Trieste from 25 April 2000 to 12 May 2000. It was organized by J. P. Demailly (Universite de Grenoble I) and R. Lazarsfeld (University of Michigan). The main topics considered were vanishing theorems, multiplyer ideal sheaves and effective results in algebraic geometry, tight closure, geometry of higher dimensional projective and Kahler manifolds, hyperbolic algebraic varieties. The school consisted of two weeks of lectures and one week of conference. This volume contains the lecture notes of most of the lectures in the first two weeks.

  13. Solitons in quadratic nonlinear photonic crystals

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2001-01-01

    We study solitons in one-dimensional quadratic nonlinear photonic crystals with modulation of both the linear and nonlinear susceptibilities. We derive averaged equations that include induced cubic nonlinearities, which can be defocusing, and we numerically find previously unknown soliton families....... Because of these induced cubic terms, solitons still exist even when the effective quadratic nonlinearity vanishes and conventional theory predicts that there can be no soliton. We demonstrate that both bright and dark forms of these solitons can propagate stably....

  14. Consequences of vanishing twins in IVF/ICSI pregnancies

    DEFF Research Database (Denmark)

    Pinborg, Anja Bisgaard; Lidegaard, Ojvind; la Cour Freiesleben, Nina

    2005-01-01

    Spontaneous reductions are a possible cause of the increased morbidity in IVF singletons. The aim of this study was to assess incidence rates of spontaneous reductions in IVF/ICSI twin pregnancies and to compare short- and long-term morbidity in survivors of a vanishing co-twin with singletons...

  15. Ursodeoxycholic acid treatment of vanishing bile duct syndromes

    NARCIS (Netherlands)

    Pusl, Thomas; Beuers, Ulrich

    2006-01-01

    Vanishing bile duct syndromes (VBDS) are characterized by progressive loss of small intrahepatic ducts caused by a variety of different diseases leading to chronic cholestasis, cirrhosis, and premature death from liver failure. The majority of adult patients with VBDS suffer from primary biliary

  16. Type 1,1-operators defined by vanishing frequency modulation

    DEFF Research Database (Denmark)

    Johnsen, Jon

    2009-01-01

    This paper presents a general definition of pseudo-differential operators of type 1,1; the definition is shown to be the largest one that is both compatible with negliible operators and stable under vanishing frequency modulation. Elaborating counter-examples of Ching, Hörmander and Parenti...

  17. Type 1,1-operators defined by vanishing frequency modulation

    DEFF Research Database (Denmark)

    Johnsen, Jon

    This paper presents a general definition of pseudo-differential operators of type 1,1; the definition is shown to be the largest one that is both compatible with negligible operators and stable under vanishing frequency modulation. Elaborating counter-examples of Ching andHörmander, type 1...

  18. Astrocytes are central in the pathomechanisms of vanishing white matter

    NARCIS (Netherlands)

    Dooves, Stephanie; Bugiani, Marianna; Postma, Nienke L.; Polder, Emiel; Land, Niels; Horan, Stephen T.; van Deijk, Anne-Lieke F.; van de Kreeke, Aleid; Jacobs, Gerbren; Vuong, Caroline; Klooster, Jan; Kamermans, Maarten; Wortel, Joke; Loos, Maarten; Wisse, Lisanne E.; Scheper, Gert C.; Abbink, Truus E. M.; Heine, Vivi M.; van der Knaap, Marjo S.

    2016-01-01

    Vanishing white matter (VWM) is a fatal leukodystrophy that is caused by mutations in genes encoding subunits of eukaryotic translation initiation factor 2B (eIF2B). Disease onset and severity are codetermined by genotype. White matter astrocytes and oligodendrocytes are almost exclusively affected;

  19. Coarsening of Ni(3)Si precipitates in binary Ni-Si alloys

    Science.gov (United States)

    Cho, Jin-Hoon

    The coarsening behavior of coherent gammasp'\\ (Nisb3Si) precipitates with volume fractions, f, ranging from 0.017 to 0.32 in binary Ni-Si alloys was investigated. All of the alloys were aged at 650sp° C for times as long as 2760 h and measurements were made of the kinetics of coarsening, particle size distributions and the evolution of particle morphologies using transmission electron microscopy. The kinetics of solute depletion were investigated using measurements of the ferromagnetic Curie temperature. We successfully overcame the difficulties in obtaining uniform spatial distributions of precipitates at small f by employing an up-quenching treatment; alloys with f less than 0.1 were pre-aged at 530sp° C prior to re-aging at the normal aging temperature of 650sp° C. Almost identical coarsening behavior exhibited by an alloy subjected to both isothermal and up-quenching treatments confirm that the up-quenching treatments do not affect any aspect of the coarsening behavior. Consistent with previous studies, the particles are spherical in shape when small and evolve to a cuboidal shape, with flat faces parallel to {}, as they grow. This shape transition was characterized quantitatively by analyzing the intensity distributions of Fast Fourier Transform spectra generated from the digitized images of TEM micrographs. The precipitates display no tendency towards becoming plate-shaped and they resist coalescence even at the largest sizes, which approach 400 nm in diameter at 2760 h of aging for higher volume fraction alloys. For f < 0.1, the kinetics of coarsening and solute depletion as well as the standard deviation of the particle size distributions decrease as f increases. This anomalous behavior has been documented previously by other investigators, but is contrary to the predictions of theories that incorporate the volume fraction effect in coarsening kinetics. We find no convincing evidence to suggest that f influences any aspect of the coarsening behavior at

  20. Nonlinear electrodynamics and cosmology

    International Nuclear Information System (INIS)

    Breton, Nora

    2010-01-01

    Nonlinear electrodynamics (NLED) generalizes Maxwell's theory for strong fields. When coupled to general relativity NLED presents interesting features like the non-vanishing of the trace of the energy-momentum tensor that leads to the possibility of violation of some energy conditions and of acting as a repulsive contribution in the Raychaudhuri equation. This theory is worth to study in cosmological and astrophysical situations characterized by strong electromagnetic and gravitational fields.

  1. A pursuit of significance of the coarsened gastric rugae in radiologic examination

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ok Dong [Chung Ang University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The radiologic upper G.I. series and gastroscopic examination with gastric biopsies of 230 cases were carried out in Korea General Hospital for the purpose of pursuit of significance of coarsened gastric rugae. Out of the above series the 26 cases showing mere radiologic finding of coarsening of the gastric mucosal rugae were selected, excluding the cases with definite evidence of ulceration, malignancies and others. The correlativity of the coarsened gastric rugae was investigated with clinical pictures, gastroscopic features and biopsy findings. The following results were obtained: 1. There were 24 cases of gastritis, 5 of stomach ulcer and 2 of stomach cancer in the 26 cases with mere finding of mucosal coarsening. 2. There was 5 cases of stomach ulcer disease revealing no radiologic evidence, but there were found tiny ulcers in 4 cases and a large ulcer crater of 1.0 cm by 1.5 cm in diameter in the other case under the gastroscopic study. 3. Two cases of stomach cancer were not detected in neither radiologic nor gastroscopic examination, however, they were found by gastric biopsy. 4. It should be strongly emphasized that the biopsy under the gastroscopic control must be followed when a radiologic evidence of coarsened gastric rugae is demonstrated.

  2. A pursuit of significance of the coarsened gastric rugae in radiologic examination

    International Nuclear Information System (INIS)

    Kim, Ok Dong

    1979-01-01

    The radiologic upper G.I. series and gastroscopic examination with gastric biopsies of 230 cases were carried out in Korea General Hospital for the purpose of pursuit of significance of coarsened gastric rugae. Out of the above series the 26 cases showing mere radiologic finding of coarsening of the gastric mucosal rugae were selected, excluding the cases with definite evidence of ulceration, malignancies and others. The correlativity of the coarsened gastric rugae was investigated with clinical pictures, gastroscopic features and biopsy findings. The following results were obtained: 1. There were 24 cases of gastritis, 5 of stomach ulcer and 2 of stomach cancer in the 26 cases with mere finding of mucosal coarsening. 2. There was 5 cases of stomach ulcer disease revealing no radiologic evidence, but there were found tiny ulcers in 4 cases and a large ulcer crater of 1.0 cm by 1.5 cm in diameter in the other case under the gastroscopic study. 3. Two cases of stomach cancer were not detected in neither radiologic nor gastroscopic examination, however, they were found by gastric biopsy. 4. It should be strongly emphasized that the biopsy under the gastroscopic control must be followed when a radiologic evidence of coarsened gastric rugae is demonstrated.

  3. A combinatorial method for the vanishing of the Poisson brackets of an integrable Lotka-Volterra system

    International Nuclear Information System (INIS)

    Itoh, Yoshiaki

    2009-01-01

    The combinatorial method is useful to obtain conserved quantities for some nonlinear integrable systems, as an alternative to the Lax representation method. Here we extend the combinatorial method and introduce an elementary geometry to show the vanishing of the Poisson brackets of the Hamiltonian structure for a Lotka-Volterra system of competing species. We associate a set of points on a circle with a set of species of the Lotka-Volterra system, where the dominance relations between points are given by the dominance relations between the species. We associate each term of the conserved quantities with a subset of points on the circle, which simplifies to show the vanishing of the Poisson brackets

  4. Structural coarsening during annealing of an aluminum plate heavily deformed using ECAE

    DEFF Research Database (Denmark)

    Mishin, Oleg V.; Zhang, Yubin; Godfrey, A.

    2015-01-01

    The microstructure and softening behaviour have been investigated in an aluminum plate heavily deformed by equal channel angular extrusion and subsequently annealed at 170 °C. It is found that at this temperature the microstructure evolves by coarsening with no apparent signs of recrystallization...... even after 2 h of annealing. Both coarsening and softening are rapid within first 10 minutes of annealing followed by a slower evolution with increasing annealing duration. Evidence of triple junction (TJ) motion during coarsening is obtained by inspecting the microstructure in one region using...... the electron backscatter diffraction technique both before and after annealing for 10 minutes. The fraction of fast-migrating TJs is found to strongly depend of the type of boundaries composing a junction. The greatest fraction of fast-migrating TJs is in the group, where all boundaries forming a junction...

  5. Experimental, computational and theoretical studies of δ′ phase coarsening in Al–Li alloys

    International Nuclear Information System (INIS)

    Pletcher, B.A.; Wang, K.G.; Glicksman, M.E.

    2012-01-01

    Experimental characterization of microstructure evolution in three binary Al–Li alloys provides critical tests of both diffusion screening theory and multiparticle diffusion simulations, which predict late-stage phase-coarsening kinetics. Particle size distributions, growth kinetics and maximum particle sizes obtained using quantitative, centered dark-field transmission electron microscopy are compared quantitatively with theoretical and computational predictions. We also demonstrate the dependence on δ′ precipitate volume fraction of the rate constant for coarsening and the microstructure’s maximum particle size, both of which remained undetermined for this alloy system for nearly a half century. Our experiments show quantitatively that the diffusion-screening theoretical description of phase coarsening yields reasonable kinetic predictions, and that useful simulations of microstructure evolution are obtained via multiparticle diffusion. The tested theory and simulation method will provide useful tools for future design of two-phase alloys for elevated temperature applications.

  6. Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

    KAUST Repository

    Yavari, Arash; Goriely, Alain

    2012-01-01

    but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan's moving frames we construct the material manifold for several examples of bodies with distributed

  7. Vanishing embryo syndrome’ in IVF/ICSI

    DEFF Research Database (Denmark)

    Hvidtjørn, Dorte; Grove, Jakob; Schendel, Diana

    2005-01-01

    BACKGROUND: In a Danish population-based cohort study assessing the risk of cerebral palsy in children bornafter IVF, we made some interesting observations regarding ‘vanishing co-embryos’. METHODS andRESULTS: All live-born children born in Denmark from 1 January 1995 to 31 December 2000 were...... included inthis analysis. The children conceived by IVF/ICSI (9444) were identified through the IVF Register, the childrenconceived without IVF/ICSI (395 025) were identified through The Danish Medical Birth Register. Main outcomemeasure was the incidence of cerebral palsy. Within the IVF/ICSI children we...... found indications of an increasedrisk of cerebral palsy in those children resulting from pregnancies, where the number of embryos transferred washigher than the number of children born. CONCLUSIONS: The association between vanishing embryo syndromeand incidence of cerebral palsy following IVF requires...

  8. Emergent gravity from vanishing energy-momentum tensor

    Energy Technology Data Exchange (ETDEWEB)

    Carone, Christopher D.; Erlich, Joshua [High Energy Theory Group, Department of Physics, College of William and Mary,Williamsburg, VA 23187-8795 (United States); Vaman, Diana [Department of Physics, University of Virginia,Box 400714, Charlottesville, VA 22904 (United States)

    2017-03-27

    A constraint of vanishing energy-momentum tensor is motivated by a variety of perspectives on quantum gravity. We demonstrate in a concrete example how this constraint leads to a metric-independent theory in which quantum gravity emerges as a nonperturbative artifact of regularization-scale physics. We analyze a scalar theory similar to the Dirac-Born-Infeld (DBI) theory with vanishing gauge fields, with the DBI Lagrangian modulated by a scalar potential. In the limit of a large number of scalars, we explicitly demonstrate the existence of a composite massless spin-2 graviton in the spectrum that couples to matter as in Einstein gravity. We comment on the cosmological constant problem and the generalization to theories with fermions and gauge fields.

  9. Emergent gravity from vanishing energy-momentum tensor

    International Nuclear Information System (INIS)

    Carone, Christopher D.; Erlich, Joshua; Vaman, Diana

    2017-01-01

    A constraint of vanishing energy-momentum tensor is motivated by a variety of perspectives on quantum gravity. We demonstrate in a concrete example how this constraint leads to a metric-independent theory in which quantum gravity emerges as a nonperturbative artifact of regularization-scale physics. We analyze a scalar theory similar to the Dirac-Born-Infeld (DBI) theory with vanishing gauge fields, with the DBI Lagrangian modulated by a scalar potential. In the limit of a large number of scalars, we explicitly demonstrate the existence of a composite massless spin-2 graviton in the spectrum that couples to matter as in Einstein gravity. We comment on the cosmological constant problem and the generalization to theories with fermions and gauge fields.

  10. Vanishing of Littlewood-Richardson polynomials is in P

    OpenAIRE

    Adve, Anshul; Robichaux, Colleen; Yong, Alexander

    2017-01-01

    J. DeLoera-T. McAllister and K. D. Mulmuley-H. Narayanan-M. Sohoni independently proved that determining the vanishing of Littlewood-Richardson coefficients has strongly polynomial time computational complexity. Viewing these as Schubert calculus numbers, we prove the generalization to the Littlewood-Richardson polynomials that control equivariant cohomology of Grassmannians. We construct a polytope using the edge-labeled tableau rule of H. Thomas-A. Yong. Our proof then combines a saturation...

  11. Compactification over coset spaces with torsion and vanishing cosmological constant

    International Nuclear Information System (INIS)

    Batakis, N.A.

    1989-01-01

    We consider the compactification of ten-dimensional Einstein-Yang-Mills theories over non-symmetric, six-dimensional homogeneous coset spaces with torsion. We examine the Einstein-Yang-Mills equations of motion requiring vanishing cosmological constant at ten and four dimensions and we present examples of compactifying solutions. It appears that the introduction of more than one radii in the coset space, when possible, may be mandatory for the existence of compactifying solutions. (orig.)

  12. Compactification over coset spaces with torsion and vanishing cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Batakis, N.A.; Farakos, K.; Koutsoumbas, G.; Zoupanos, G.; Kapetanakis, D.

    1989-04-13

    We consider the compactification of ten-dimensional Einstein-Yang-Mills theories over non-symmetric, six-dimensional homogeneous coset spaces with torsion. We examine the Einstein-Yang-Mills equations of motion requiring vanishing cosmological constant at ten and four dimensions and we present examples of compactifying solutions. It appears that the introduction of more than one radii in the coset space, when possible, may be mandatory for the existence of compactifying solutions.

  13. Near horizon structure of extremal vanishing horizon black holes

    Directory of Open Access Journals (Sweden)

    S. Sadeghian

    2015-11-01

    Full Text Available We study the near horizon structure of Extremal Vanishing Horizon (EVH black holes, extremal black holes with vanishing horizon area with a vanishing one-cycle on the horizon. We construct the most general near horizon EVH and near-EVH ansatz for the metric and other fields, like dilaton and gauge fields which may be present in the theory. We prove that (1 the near horizon EVH geometry for generic gravity theory in generic dimension has a three dimensional maximally symmetric subspace; (2 if the matter fields of the theory satisfy strong energy condition either this 3d part is AdS3, or the solution is a direct product of a locally 3d flat space and a d−3 dimensional part; (3 these results extend to the near horizon geometry of near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry. We present some specific near horizon EVH geometries in 3, 4 and 5 dimensions for which there is a classification. We also briefly discuss implications of these generic results for generic (gauged supergravity theories and also for the thermodynamics of near-EVH black holes and the EVH/CFT proposal.

  14. Three theorems on near horizon extremal vanishing horizon geometries

    Directory of Open Access Journals (Sweden)

    S. Sadeghian

    2016-02-01

    Full Text Available EVH black holes are Extremal black holes with Vanishing Horizon area, where vanishing of horizon area is a result of having a vanishing one-cycle on the horizon. We prove three theorems regarding near horizon geometry of EVH black hole solutions to generic Einstein gravity theories in diverse dimensions. These generic gravity theories are Einstein–Maxwell-dilaton-Λ theories, and gauged or ungauged supergravity theories with U(1 Maxwell fields. Our three theorems are: (1 The near horizon geometry of any EVH black hole has a three dimensional maximally symmetric subspace. (2 If the energy momentum tensor of the theory satisfies strong energy condition either this 3d part is an AdS3, or the solution is a direct product of a locally 3d flat space and a d−3 dimensional part. (3 These results extend to the near horizon geometry of near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry.

  15. Coarsening behavior of lath and its effect on creep rates in tempered martensitic 9Cr-W steels

    International Nuclear Information System (INIS)

    Abe, F.

    2004-01-01

    The coarsening behavior of martensite lath has been investigated by means of transmission electron microscopy for tempered martensitic 9 wt.% Cr-(0, 1, 2, 4 wt.%) W steels during creep at 823-923 K. During creep, the recovery of excess dislocations, the agglomeration of carbides and the coarsening of laths take place. The coarsening of laths with absorbing excess dislocations is the major process in the creep acceleration. The coarsening rate of lath decreases with increasing W concentration, which is correlated with the rate of Ostwald ripening of M 23 C 6 carbides. The progressive local-coalescence of two adjacent laths boundaries near the Y-junction causes the movement of Y-junction, resulting in the coarsening of lath

  16. A kinetic Monte Carlo study of coarsening resistance of novel core/shell precipitates

    International Nuclear Information System (INIS)

    Zhang, Xuan; Gao, Wenpei; Bellon, Pascal; Averback, Robert S.; Zuo, Jian-Min

    2014-01-01

    A novel approach towards the design of coarsening-resistant nanoprecipitates in structural alloys was investigated by kinetic Monte Carlo (KMC) simulation. The approach is motivated by recent experimental results in Cu–Nb–W alloys showing that room temperature ion irradiation resulted in W nanoprecipitation, leading to exceptional stability of W-rich-core/Nb-rich-shell nanoprecipitates formed following thermal annealing (Zhang et al., 2013 [11]). Here, image simulations of atomically resolved scanning transmission electron microscopy are performed to establish that these W nanoprecipitates are highly ramified. Thermal precipitate coarsening in an A–B–C ternary alloy similar to Cu–Nb–W is then studied by KMC simulations, where the highly immiscible and refractory C solute atoms are initially distributed into fractal nanoprecipitates, or cores, which become coated by a shell of B atoms during elevated temperature annealing. Compared with nanoprecipitates generated by compact C cores, the ramified nanoprecipitates result in exceptionally high trapping efficiency of B solute atoms during thermal coarsening, and the efficiency increases with the cluster size. The KMC results are analyzed and rationalized by noting that, owing to the Gibbs–Thomson effect, when the curvatures of the shell of the precipitates are zero or negative, the microstructure is coarsening-resistant. Such morphology can be realized by facets, or by dynamic balance within positive, negative and zero curvatures

  17. A solvable model for coarsening soap froths and other domain boundary networks in two dimensions

    International Nuclear Information System (INIS)

    Flyvbjerg, H.; Jeppesen, C.

    1990-09-01

    The dynamical processes leading to coarsening of soap froths and other domain boundary networks in two dimensions are described statistically by a 'random neighbour model'. The model is solved using the principle of maximum entropy. The solution describes normal growth with realistic probability distribution for area and topology. (orig.)

  18. Vanishing of cohomology over Cohen–Macaulay rings

    DEFF Research Database (Denmark)

    Christensen, Lars Winther; Holm, Henrik Granau

    2012-01-01

    A 2003 counterexample to a conjecture of Auslander brought attention to a family of rings—colloquially called AC rings—that satisfy a natural condition on vanishing of cohomology. Several results attest to the remarkable homological properties of AC rings, but their definition is barely operational......, and it remains unknown if they form a class that is closed under typical constructions in ring theory. In this paper, we study transfer of the AC property along local homomorphisms of Cohen–Macaulay rings. In particular, we show that the AC property is preserved by standard procedures in local algebra. Our...

  19. Anti-levitation of Landau levels in vanishing magnetic fields

    Science.gov (United States)

    Pan, W.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.; Tsui, D. C.

    Soon after the discovery of the quantum Hall effects in two-dimensional electron systems, the question on the fate of the extended states in a Landau level in vanishing magnetic (B) field arose. Many theoretical models have since been proposed, and experimental results remain inconclusive. In this talk, we report experimental observation of anti-levitation behavior of Landau levels in vanishing B fields (down to as low as B 58 mT) in a high quality heterojunction insulated-gated field-effect transistor (HIGFET). We observed that, in the Landau fan diagram of electron density versus magnetic field, the positions of the magneto-resistance minima at Landau level fillings ν = 4, 5, 6 move below the ``traditional'' Landau level line to lower electron densities. This clearly differs from what was observed in the earlier experiments where in the same Landau fan plot the density moved up. Our result strongly supports the anti-levitation behavior predicted recently. Moreover, the even and odd Landau level filling states show quantitatively different behaviors in anti-levitation, suggesting that the exchange interactions, which are important at odd fillings, may play a role. SNL is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energys National Nuclear Security Administration under contract DE-AC04-94AL85000.

  20. Overlapping Schwarz for Nonlinear Problems. An Element Agglomeration Nonlinear Additive Schwarz Preconditioned Newton Method for Unstructured Finite Element Problems

    Energy Technology Data Exchange (ETDEWEB)

    Cai, X C; Marcinkowski, L; Vassilevski, P S

    2005-02-10

    This paper extends previous results on nonlinear Schwarz preconditioning ([4]) to unstructured finite element elliptic problems exploiting now nonlocal (but small) subspaces. The non-local finite element subspaces are associated with subdomains obtained from a non-overlapping element partitioning of the original set of elements and are coarse outside the prescribed element subdomain. The coarsening is based on a modification of the agglomeration based AMGe method proposed in [8]. Then, the algebraic construction from [9] of the corresponding non-linear finite element subproblems is applied to generate the subspace based nonlinear preconditioner. The overall nonlinearly preconditioned problem is solved by an inexact Newton method. Numerical illustration is also provided.

  1. In situ TEM study of the coarsening of carbon black supported Pt nanoparticles in hydrogen

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Wang, Yan; Jensen, Jens Oluf

    2017-01-01

    The control of sizes and shapes of nanostructures is of tremendous importance for the catalytic activity in electrochemistry and in catalysis more generally. However, due to relatively large surface free energies, nanostructures often sinter to form coarser and more stable structures that may...... not have the intended physicochemical properties. Pt is known to be a very active catalyst in several chemical reactions and for example as carbon supported nanoparticles in fuel cells. The presentation focusses on coarsening mechanisms of Pt nanoparticles supported on carbon black during exposure...... to hydrogen. By means of in situ transmission electron microscopy (TEM), Pt nanoparticle coarsening was monitored in 6 mbar 20 % H2/Ar while ramping up the temperature to ca. 900 °C. Time-resolved TEM images directly reveal that separated ca. 3 nm sized Pt nanoparticles in the pure hydrogen environment...

  2. High annealing temperature induced rapid grain coarsening for efficient perovskite solar cells.

    Science.gov (United States)

    Cao, Xiaobing; Zhi, Lili; Jia, Yi; Li, Yahui; Cui, Xian; Zhao, Ke; Ci, Lijie; Ding, Kongxian; Wei, Jinquan

    2018-08-15

    Thermal annealing plays multiple roles in fabricating high quality perovskite films. Generally, it might result in large perovskite grains by elevating annealing temperature, but might also lead to decomposition of perovskite. Here, we study the effects of annealing temperature on the coarsening of perovskite grains in a temperature range from 100 to 250 °C, and find that the coarsening rate of the perovskite grain increase significantly with the annealing temperature. Compared with the perovskite films annealed at 100 °C, high quality perovskite films with large columnar grains are obtained by annealing perovskite precursor films at 250 °C for only 10 s. As a result, the power conversion efficiency of best solar cell increased from 12.35% to 16.35% due to its low recombination rate and high efficient charge transportation in solar cells. Copyright © 2018. Published by Elsevier Inc.

  3. Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture

    Science.gov (United States)

    Chen, Chih-Hung; Cambonie, Tristan; Lazarus, Veronique; Nicoli, Matteo; Pons, Antonio J.; Karma, Alain

    2015-12-01

    A planar crack generically segments into an array of "daughter cracks" shaped as tilted facets when loaded with both a tensile stress normal to the crack plane (mode I) and a shear stress parallel to the crack front (mode III). We investigate facet propagation and coarsening using in situ microscopy observations of fracture surfaces at different stages of quasistatic mixed-mode crack propagation and phase-field simulations. The results demonstrate that the bifurcation from propagating a planar to segmented crack front is strongly subcritical, reconciling previous theoretical predictions of linear stability analysis with experimental observations. They further show that facet coarsening is a self-similar process driven by a spatial period-doubling instability of facet arrays.

  4. Vanishing twin syndrome among ART singletons and pregnancy outcomes.

    Science.gov (United States)

    Magnus, Maria C; Ghaderi, Sara; Morken, Nils-Halvdan; Magnus, Per; Bente Romundstad, Liv; Skjærven, Rolv; Wilcox, Allen J; Eldevik Håberg, Siri

    2017-11-01

    Among babies born by ART, do singleton survivors of a vanishing twin have lower birth weight than other singletons? Vanishing twin syndrome (VTS) was associated with lower birth weight among ART singletons; a sibship analysis indicated that the association was not confounded by maternal characteristics that remain stable between deliveries. Previous studies indicate that ART singletons with VTS have increased risk of adverse pregnancy outcomes, compared with other ART singletons. The potential contribution of unmeasured maternal background characteristics has been unclear. This was a Norwegian population-based registry study, including 17 368 mothers with 20 410 ART singleton deliveries between January 1984 and December 2013. The study population included 17 291 ART singletons without VTS, 638 ART singletons with VTS and 2418 ART singletons with uncertain vanishing twin status. We estimated differences in birth weight and gestational age comparing ART singletons with VTS first to all ART singletons without VTS, and subsequently to their ART siblings without VTS, using random- and fixed-effects linear regression, respectively. The corresponding comparisons for the associations with preterm birth and small for gestational age (SGA) were conducted using random-and fixed-effects logistic regression. The sibling analysis of preterm birth included 587 discordant siblings, while the sibling analysis of SGA included 674 discordant siblings. ART singletons with VTS had lower birth weight when compared to all ART singletons without VTS, with an adjusted mean difference (95% CI) of -116 g (-165, -67). When we compared ART singletons with VTS to their ART singletons sibling without VTS, the adjusted mean difference was -112 g (-209, -15). ART singletons with VTS also had increased risk of being born SGA, with an adjusted odds ratio (OR) (95% CI) of 1.48 (1.07, 2.03) compared to all ART singletons without VTS, and 2.79 (1.12, 6.91) in the sibship analyses. ART singletons with

  5. Vanishing auxiliary variables in PPS sampling - with applications in microscopy

    DEFF Research Database (Denmark)

    Andersen, Ina Trolle; Hahn, Ute; Jensen, Eva B. Vedel

    Recently, non-uniform sampling has been suggested in microscopy to increase efficiency. More precisely, sampling proportional to size (PPS) has been introduced where the probability of sampling a unit in the population is proportional to the value of an auxiliary variable. Unfortunately, vanishing...... auxiliary variables are a common phenomenon in microscopy and, accordingly, part of the population is not accessible, using PPS sampling. We propose a modification of the design, for which an optimal solution can be found, using a model assisted approach. The optimal design has independent interest...... in sampling theory. We verify robustness of the new approach by numerical results, and we use real data to illustrate the applicability....

  6. The “Axial” (“Vanishing Axis” Perspective

    Directory of Open Access Journals (Sweden)

    Daniel Sofron

    2015-11-01

    Full Text Available The present paper approaches the axial perspective, a method of spatial representation that precedes the invention of the Renaissance geometrical perspective. Despite being typical to ancient Greek and Roman art, the axial perspective can also be identified during the Middle Ages and the early Renaissance period and it represents the first form of systematic convergence of parallel lines. At the same time, the paper presents Erwin Panofsky's theories on this spatial suggestion method. Trying to offer it a scientific foundation, the researcher builds a system that he calls "the vanishing axis perspective" and puts forward a series of arguments in favour of the existence of such a perspective. Although the axial perspectival constructions imply awkward superimpositions of planes that might seem geometrically inaccurate, this method of spatial structuring of the image constitutes an important stage in the process of identifying solutions for the faithful reproduction of concrete reality and an essential stepin the development process of thevanishing point perspective.

  7. [Nonlinear magnetohydrodynamics

    International Nuclear Information System (INIS)

    1994-01-01

    Resistive MHD equilibrium, even for small resistivity, differs greatly from ideal equilibrium, as do the dynamical consequences of its instabilities. The requirement, imposed by Faraday's law, that time independent magnetic fields imply curl-free electric fields, greatly restricts the electric fields allowed inside a finite-resistivity plasma. If there is no flow and the implications of the Ohm's law are taken into account (and they need not be, for ideal equilibria), the electric field must equal the resistivity times the current density. The vanishing of the divergence of the current density then provides a partial differential equation which, together with boundary conditions, uniquely determines the scalar potential, the electric field, and the current density, for any given resistivity profile. The situation parallels closely that of driven shear flows in hydrodynamics, in that while dissipative steady states are somewhat more complex than ideal ones, there are vastly fewer of them to consider. Seen in this light, the vast majority of ideal MHD equilibria are just irrelevant, incapable of being set up in the first place. The steady state whose stability thresholds and nonlinear behavior needs to be investigated ceases to be an arbitrary ad hoc exercise dependent upon the whim of the investigator, but is determined by boundary conditions and choice of resistivity profile

  8. Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren

    2016-01-01

    The coarsening of supported palladium nanoparticles in an oxidizing atmosphere was studied in situ by means of transmission electron microscopy (TEM). Specifically, the Pd nanoparticles were dispersed on a planar and amorphous Al2O3 support and were observed during the exposure to 10 mbar technical...... for the Ostwald ripening process indicates that the observed change in the particle size distribution can be accounted for by wetting of the Al2O3 support by the larger Pd nanoparticles....

  9. Multigrid techniques with non-standard coarsening and group relaxation methods

    International Nuclear Information System (INIS)

    Danaee, A.

    1989-06-01

    In the usual (standard) multigrid methods, doubling of grid sizes with different smoothing iterations (pointwise, or blockwise) has been considered by different authors. Some have indicated that a large coarsening can also be used, but is not beneficial (cf. H3, p.59). In this paper, it is shown that with a suitable blockwise smoothing scheme, some advantages could be achieved even with a factor of H l-1 /h l = 3. (author). 10 refs, 2 figs, 6 tabs

  10. Three is much more than two in coarsening dynamics of cyclic competitions

    Science.gov (United States)

    Mitarai, Namiko; Gunnarson, Ivar; Pedersen, Buster Niels; Rosiek, Christian Anker; Sneppen, Kim

    2016-04-01

    The classical game of rock-paper-scissors has inspired experiments and spatial model systems that address the robustness of biological diversity. In particular, the game nicely illustrates that cyclic interactions allow multiple strategies to coexist for long-time intervals. When formulated in terms of a one-dimensional cellular automata, the spatial distribution of strategies exhibits coarsening with algebraically growing domain size over time, while the two-dimensional version allows domains to break and thereby opens the possibility for long-time coexistence. We consider a quasi-one-dimensional implementation of the cyclic competition, and study the long-term dynamics as a function of rare invasions between parallel linear ecosystems. We find that increasing the complexity from two to three parallel subsystems allows a transition from complete coarsening to an active steady state where the domain size stays finite. We further find that this transition happens irrespective of whether the update is done in parallel for all sites simultaneously or done randomly in sequential order. In both cases, the active state is characterized by localized bursts of dislocations, followed by longer periods of coarsening. In the case of the parallel dynamics, we find that there is another phase transition between the active steady state and the coarsening state within the three-line system when the invasion rate between the subsystems is varied. We identify the critical parameter for this transition and show that the density of active boundaries has critical exponents that are consistent with the directed percolation universality class. On the other hand, numerical simulations with the random sequential dynamics suggest that the system may exhibit an active steady state as long as the invasion rate is finite.

  11. Vanishing Ponds and Regional Water Resources in Taoyuan, Taiwan

    Directory of Open Access Journals (Sweden)

    Yuei-An Liou

    2015-01-01

    Full Text Available Taiwan has a Subtropic to Tropical climate, but its precipitation varies widely in response to seasonal effects and weather events such as Typhoon and Meiyu systems. Precipitation must be held back in reservoirs to provide and regulate sufficient water supply. Balancing the irregular precipitation and increasing water demands generates tremendous pressure on water resources management for the water stored in the Shihmen Reservoir, which is the major unitary water supply system in the Greater Taoyuan Area. Such pressure will be significantly enlarged due to the huge 17 billion USD Taoyuan Aerotropolis Project. In earlier days many small artificial ponds (a common terminology in this article, including irrigation ponds, fishery ponds and others, were built to cope with water shortages in Taoyuan County. These small storage ponds provided a solution that resolved seasonal precipitation shortages. Unfortunately, these ponds have been vanishing one after another one due to regional industrialization and urbanization in recent decades and less than 40% of them still remain today. There is great urgency and importance to investigating the link between vanishing ponds and water resources management. Remote sensing technology was used in this study to monitor the environmental consequences in the Taoyuan area by conducting multi-temporal analysis on the changes in water bodies, i.e., ponds. SPOT satellite images taken in 1993, 2003, and 2010 were utilized to analyze and assess the importance of small-scale ponds as water conservation facilities. It was found that, during the seventeen years from 1993 - 2010, the number of irrigation ponds decreased by 35.94%. These ponds can reduce the burden on the major reservoir and increase the water recycling rate if they are properly conserved. They can also improve rainfall interception and surface detention capabilities, and provide another planning advantage for regional water management.

  12. Boundary layers and the vanishing viscosity limit for incompressible 2D flow

    OpenAIRE

    Filho, Milton C. Lopes

    2007-01-01

    This manuscript is a survey on results related to boundary layers and the vanishing viscosity limit for incompressible flow. It is the lecture notes for a 10 hour minicourse given at the Morningside Center, Academia Sinica, Beijing, PRC from 11/28 to 12/07, 2007. The main topics covered are: a derivation of Prandtl's boundary layer equation; an outline of the rigorous theory of Prandtl's equation, without proofs; Kato's criterion for the vanishing viscosity limit; the vanishing viscosity limi...

  13. Calculating effective diffusivities in the limit of vanishing molecular diffusion

    International Nuclear Information System (INIS)

    Pavliotis, G.A.; Stuart, A.M.; Zygalakis, K.C.

    2009-01-01

    In this paper we study the problem of the numerical calculation (by Monte Carlo methods) of the effective diffusivity for a particle moving in a periodic divergent-free velocity field, in the limit of vanishing molecular diffusion. In this limit traditional numerical methods typically fail, since they do not represent accurately the geometry of the underlying deterministic dynamics. We propose a stochastic splitting method that takes into account the volume-preserving property of the equations of motion in the absence of noise, and when inertial effects can be neglected. An extension of the method is then proposed for the cases where the noise has a non-trivial time-correlation structure and when inertial effects cannot be neglected. The method of modified equations is used to explain failings of Euler-based methods. The new stochastic geometric integrators are shown to outperform standard Euler-based integrators. Various asymptotic limits of physical interest are investigated by means of numerical experiments, using the new integrators

  14. Vanishing tattoo multi-sensor for biomedical diagnostics

    Science.gov (United States)

    Moczko, E.; Meglinski, I.; Piletsky, S.

    2008-04-01

    Currently, precise non-invasive diagnostics systems for the real-time multi detection and monitoring of physiological parameters and chemical analytes in the human body are urgently required by clinicians, physiologists and bio-medical researchers. We have developed a novel cost effective smart 'vanishing tattoo' (similar to temporary child's tattoos) consisting of environmental-sensitive dyes. Painlessly impregnated into the skin the smart tattoo is capable of generating optical/fluorescence changes (absorbance, transmission, reflectance, emission and/or luminescence within UV, VIS or NIR regions) in response to physical or chemical changes. These changes allow the identification of colour pattern changes similar to bar-code scanning. Such a system allows an easy, cheap and robust comprehensive detection of various parameters and analytes in a small volume of sample (e.g. variations in pH, temperature, ionic strength, solvent polarity, presence of redox species, surfactants, oxygen). These smart tattoos have possible applications in monitoring the progress of disease and transcutaneous drug delivery. The potential of this highly innovative diagnostic tool is wide and diverse and can impact on routine clinical diagnostics, general therapeutic management, skin care and cosmetic products testing as well as fundamental physiological investigations.

  15. Direct observation of grain rotations during coarsening of a semisolid Al-Cu alloy

    DEFF Research Database (Denmark)

    Dake, Jules M.; Oddershede, Jette; Sørensen, Henning O.

    2016-01-01

    ideal arrangements of constituent powders while ignoring their underlying crystallinity, achieve at best a qualitative description of the rearrangement, densification, and coarsening of powder compacts during thermal processing. Treating a semisolid Al-Cu alloy as a model system for late-stage sintering......Sintering is a key technology for processing ceramic and metallic powders into solid objects of complex geometry, particularly in the burgeoning field of energy storage materials. The modeling of sintering processes, however, has not kept pace with applications. Conventional models, which assume...

  16. Chemical-Reaction-Controlled Phase Separated Drops: Formation, Size Selection, and Coarsening

    Science.gov (United States)

    Wurtz, Jean David; Lee, Chiu Fan

    2018-02-01

    Phase separation under nonequilibrium conditions is exploited by biological cells to organize their cytoplasm but remains poorly understood as a physical phenomenon. Here, we study a ternary fluid model in which phase-separating molecules can be converted into soluble molecules, and vice versa, via chemical reactions. We elucidate using analytical and simulation methods how drop size, formation, and coarsening can be controlled by the chemical reaction rates, and categorize the qualitative behavior of the system into distinct regimes. Ostwald ripening arrest occurs above critical reaction rates, demonstrating that this transition belongs entirely to the nonequilibrium regime. Our model is a minimal representation of the cell cytoplasm.

  17. Vanishing twins: a predictor of small-for-gestational age in IVF singletons

    DEFF Research Database (Denmark)

    Pinborg, Anja; Lidegaard, Ojvind; Freiesleben, Nina la Cour

    2007-01-01

    The purpose of this study was to assess the effect of a vanishing twin on the risk of being small-for-gestational age (SGA) in in vitro fertilization (IVF) singletons.......The purpose of this study was to assess the effect of a vanishing twin on the risk of being small-for-gestational age (SGA) in in vitro fertilization (IVF) singletons....

  18. Predicting Sediment Thickness on Vanished Ocean Crust Since 200 Ma

    Science.gov (United States)

    Dutkiewicz, A.; Müller, R. D.; Wang, X.; O'Callaghan, S.; Cannon, J.; Wright, N. M.

    2017-12-01

    Tracing sedimentation through time on existing and vanished seafloor is imperative for constraining long-term eustasy and for calculating volumes of subducted deep-sea sediments that contribute to global geochemical cycles. We present regression algorithms that incorporate the age of the ocean crust and the mean distance to the nearest passive margin to predict sediment thicknesses and long-term decompacted sedimentation rates since 200 Ma. The mean sediment thickness decreases from ˜220 m at 200 Ma to a minimum of ˜140 m at 130 Ma, reflecting the replacement of old Panthalassic ocean floor with young sediment-poor mid-ocean ridges, followed by an increase to ˜365 m at present-day. This increase reflects the accumulation of sediments on ageing abyssal plains proximal to passive margins, coupled with a decrease in the mean distance of any parcel of ocean crust to the nearest passive margin by over 700 km, and a doubling of the total passive margin length at present-day. Mean long-term sedimentation rates increase from ˜0.5 cm/ky at 160 Ma to over 0.8 cm/ky today, caused by enhanced terrigenous sediment influx along lengthened passive margins, superimposed by the onset of ocean-wide carbonate sedimentation. Our predictive algorithms, coupled to a plate tectonic model, provide a framework for constraining the seafloor sediment-driven eustatic sea-level component, which has grown from ˜80 to 210 m since 120 Ma. This implies a long-term sea-level rise component of 130 m, partly counteracting the contemporaneous increase in ocean basin depth due to progressive crustal ageing.

  19. A temperature dependent cyclic plasticity model for hot work tool steel including particle coarsening

    Science.gov (United States)

    Jilg, Andreas; Seifert, Thomas

    2018-05-01

    Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material's yield strength in highly loaded areas as e.g. in small radii in die cavities. To sustain the high loads, the hot forming tools are typically made of martensitic hot work steels. While temperatures for annealing of the tool steels usually lie in the range between 400 and 600 °C, the steels may experience even higher temperatures during hot forming, resulting in softening of the material due to coarsening of strengthening particles. In this paper, a temperature dependent cyclic plasticity model for the martensitic hot work tool steel 1.2367 (X38CrMoV5-3) is presented that includes softening due to particle coarsening and that can be applied in finite-element calculations to assess the effect of softening on the thermomechanical fatigue life of hot work tools. To this end, a kinetic model for the evolution of the mean size of secondary carbides based on Ostwald ripening is coupled with a cyclic plasticity model with kinematic hardening. Mechanism-based relations are developed to describe the dependency of the mechanical properties on carbide size and temperature. The material properties of the mechanical and kinetic model are determined on the basis of tempering hardness curves as well as monotonic and cyclic tests.

  20. Numerical simulation of two-dimensional late-stage coarsening for nucleation and growth

    International Nuclear Information System (INIS)

    Akaiwa, N.; Meiron, D.I.

    1995-01-01

    Numerical simulations of two-dimensional late-stage coarsening for nucleation and growth or Ostwald ripening are performed at area fractions 0.05 to 0.4 using the monopole and dipole approximations of a boundary integral formulation for the steady state diffusion equation. The simulations are performed using two different initial spatial distributions. One is a random spatial distribution, and the other is a random spatial distribution with depletion zones around the particles. We characterize the spatial correlations of particles by the radial distribution function, the pair correlation functions, and the structure function. Although the initial spatial correlations are different, we find time-independent scaled correlation functions in the late stage of coarsening. An important feature of the late-stage spatial correlations is that depletion zones exist around particles. A log-log plot of the structure function shows that the slope at small wave numbers is close to 4 and is -3 at very large wave numbers for all area fractions. At large wave numbers we observe oscillations in the structure function. We also confirm the cubic growth law of the average particle radius. The rate constant of the cubic growth law and the particle size distribution functions are also determined. We find qualitatively good agreement between experiments and the present simulations. In addition, the present results agree well with simulation results using the Cahn-Hilliard equation

  1. Investigation of Dendrite Coarsening in Complex Shaped Lamellar Graphite Iron Castings

    Directory of Open Access Journals (Sweden)

    Péter Svidró

    2017-07-01

    Full Text Available Shrinkage porosity and metal expansion penetration are two casting defects that appear frequently during the production of complex-shaped lamellar graphite iron components. These casting defects are formed during the solidification and usually form in the part of the casting which solidifies last. The position of the area that solidifies last is dependent on the thermal conditions. Test castings with thermal conditions like those existing in a complex-shaped casting were successfully applied to provoke a shrinkage porosity defect and a metal expansion penetration defect. The investigation of the primary dendrite morphology in the defected positions indicates a maximum intradendritic space, where the shrinkage porosity and metal expansion penetration defects appear. Moving away from the defect formation area, the intradendritic space decreases. A comparison of the intradendritic space with the simulated local solidification times indicates a strong relationship, which can be explained by the dynamic coarsening process. More specifically, long local solidification times facilitates the formation of a locally coarsened austenite morphology. This, in turn, enables the formation of a shrinkage porosity or a metal expansion penetration.

  2. The coarsening process of Ge precipitates in an Al-4 wt.% Ge alloy

    Energy Technology Data Exchange (ETDEWEB)

    Deaf, G.H

    2004-05-01

    In this paper the results of a quantitative transmission electron microscopy (TEM) investigation of the precipitation process of Ge in an Al-4 wt.% Ge alloy are described. Two crystallographic orientation relationships between the irregular germanium precipitate and aluminum matrix were found to be [1 0 0]{sub Ge} || [1 1 0]{sub Al} and [1 1 4]{sub Ge} || [1 0 0]{sub Al}. The irregular germanium precipitates formed on [0 0 1]{sub Al} habit planes. The origin of the irregular shape is due to the existence of a highly anisotropic interfacial energy as well as in an isotropic growth rate along <1 1 0>{sub A1} directions. Particles sizes were determined for variety of isothermal ageing times at 348, 423 and 523 K. The coarsening of the different morphologies of Ge precipitates was found to obey Ostwald ripening kinetics. The TEM results showed that the coarsening of irregular particles was due to the interfacial coalescence between these particles. Nine different morphologies have been distinguished in the form of (i) irregular particles, (ii) spheres, (iii) hexagonal plates, (iv) rods, (v) triangular plates, (vi) laths, (vii) small tetrahedra, (viii) rectangular plates, and (ix) Lamellae shape.

  3. Kibble-Zurek Scaling and String-Net Coarsening in Topologically Ordered Systems

    Science.gov (United States)

    Khemani, Vedika; Chandran, Anushya; Burnell, F. J.; Sondhi, S. L.

    2013-03-01

    We consider the non-equilibrium dynamics of topologically ordered systems, such as spin liquids, driven across a continuous phase transition into proximate phases with no, or reduced, topological order. This dynamics exhibits scaling in the spirit of Kibble and Zurek but now without the presence of symmetry breaking and a local order parameter. The non-equilibrium dynamics near the critical point is universal in a particular scaling limit. The late stages of the process are seen to exhibit slow, quantum coarsening dynamics for the extended string-nets characterizing the topological phase, a potentially interesting signature of topological order. Certain gapped degrees of freedom that could potentially destroy coarsening are, at worst, dangerously irrelevant in the scaling limit. We also note a time dependent amplification of the energy splitting between topologically degenerate states on closed manifolds. We illustrate these phenomena in the context of particular phase transitions out of the abelian Z2 topologically ordered phase of the toric code, and the non-abelian SU(2)k ordered phases of the relevant Levin-Wen models. This research was supported in part by the National Science Foundation under Grant No. NSF PHY11-25915 and DMR 10-06608.

  4. Vanishing De Vega annuloplasty for functional tricuspid regurgitation.

    Science.gov (United States)

    Duran, C M; Kumar, N; Prabhakar, G; Ge, Z; Bianchi, S; Gometza, B

    1993-10-01

    pulmonary arteriolar resistance can be adequately treated by a vanishing De Vega annuloplasty, which will stent the tricuspid anulus for about 4 months.

  5. Three dimensional characterization of nickel coarsening in solid oxide cells via ex-situ ptychographic nano-tomography

    DEFF Research Database (Denmark)

    De Angelis, Salvatore; Jørgensen, Peter Stanley; Tsai, Esther Hsiao Rho

    2018-01-01

    Nickel coarsening is considered a significant cause of solid oxide cell (SOC) performance degradation. Therefore, understanding the morphological changes in the nickel-yttria stabilized zirconia (Ni-YSZ) fuel electrode is crucial for the wide spread usage of SOC technology. This paper reports...... a study of the initial 3D microstructure evolution of a SOC analyzed in the pristine state and after 3 and 8 h of annealing at 850 °C, in dry hydrogen. The analysis of the evolution of the same location of the electrode shows a substantial change of the nickel and pore network during the first 3 h...... of treatment, while only negligible changes are observed after 8 h. The nickel coarsening results in loss of connectivity in the nickel network, reduced nickel specific surface area and decreased total triple phase boundary density. For the condition of this experiment, nickel coarsening is shown...

  6. Computational thermodynamic investigations of growth and coarsening of laves phase precipitates in 12%Cr creep resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Prat, O.; Rojas, D. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Garcia, J.; Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Bochum Univ. (Germany)

    2010-07-01

    Precipitation phenomena in 12%Cr high alloyed steels have been investigated at creep conditions of 650 and 150 MPa up to 6.500 hours in two different alloys. Growth and coarsening of Laves phase was determined experimentally by measuring the size of Laves phase on crept samples using scanning transmission electron microscopy (STEM). The simulations were performed using the software DICTRA based on the assumption the local equilibrium at the moving phase interface. For equilibrium calculations, the Thermo-Calc software was used. The experimental results were compared with DICTRA simulations, showing good agreement. Both the quantitative metallographic measurements as well as the simulations indicate very low coarsening for Laves Phase. The influence of different elements such as Co, Si and Cu on coarsening for Laves phase was simulated. (orig.)

  7. Non-linear realizations of supersymmetry with off-shell central charges

    International Nuclear Information System (INIS)

    Santos Filho, P.B.; Oliveira Rivelles, V. de.

    1985-01-01

    A new class of non-linear realizations of the extended supersymmetry algebra with central charges is presented. They were obtained by applying the technique of dimensional reduction by Legendre transformation to a non-linear realization without central charges in one higher dimension. As a result an off-shell central charge is obtained. The non-linear lagrangian is the same as is the case of vanishing central charge. On-shell the central charge vanishes so this non-linear realization differs from that without central charges only off-shell. It is worked in two dimensions and its extension to higher dimensions is discussed. (Author) [pt

  8. Structure and grain coarsening during the processing of engineering ceramics. Ph.D. Thesis - Leeds Univ., United Kingdom

    Science.gov (United States)

    Shaw, Nancy J.

    1987-01-01

    Studies have been made of three ceramic systems (Al2O3, Y2O3/MgO, and SiC/C/B), both to explore a surface area/density diagram approach to examining the coarsening processes during sintering and to explore an alternative coarsening parameter, i.e., the grain boundary surface area (raising it at a given value of the density) and not the pore surface area; therefore, pinning of the grain boundaries by solid-solution drag is the only function evidenced by these results. The importance of such pinning even at densities as low as 75% of theoretical is linked to the existence of microstructural inhomogeneities. The early stages of sintering of Y2O3 powder have been examined using two techniques, BET surface area analysis and transmission electron microscopy. Each has given some insight into the process occurring and, used together, have provided some indication of the effect of MgO on coarsening during sintering. Attempts to further elucidate effects of MgO on the coarsening behavior of Y2O3 by the surface area/density diagram approach were unsuccessful due to masking effects of contaminating reactions during sintering and/or thermal etching. The behavior of the undoped SiC which only coarsens can be clearly distinguished by the surface area/density diagram from that of SiC/C/B which also concurrently densifies. Little additional information was obtainable by this method due to unfavorable sample etching characteristics. The advantages, disadvantages, and difficulties of application of these techniques to the study of coarsening during sintering are discussed.

  9. Coarsening behaviour and interfacial structure of γ′ precipitates in Co-Al-W based superalloys

    International Nuclear Information System (INIS)

    Vorontsov, V.A.; Barnard, J.S.; Rahman, K.M.; Yan, H.-Y.; Midgley, P.A.; Dye, D.

    2016-01-01

    This work discusses the effects of alloying on the coarsening behaviour of the L1 2 ordered γ ′ phase and the structure of the γ/γ ′ interfaces in three Co-Al-W base superalloys aged at ∼90 °C below the respective solvus temperatures: Co-7Al-7W, Co-10Al-5W-2Ta and Co-7Al-7W-20Ni (at.%). The coarsening kinetics are adequately characterised by the classical Lifshitz-Slyozov-Wagner model for Ostwald ripening. Co-7Al-7W exhibited much slower coarsening than its quaternary derivatives. Alloying can be exploited to modify the coarsening kinetics either by increasing the solvus temperature by adding tantalum, or by adding nickel to shift the rate controlling mechanism towards dependence on the diffusion of aluminium rather than tungsten. Lattice resolution STEM imaging was used to measure the widths of the order-disorder (structural) and Z-contrast (compositional) gradients across the γ/γ ′ interfaces. Similarly to nickel base superalloys, the compositional gradient was found to be wider than the structural. Co-7Al-7W-20Ni had much wider interface gradients than Co-7Al-7W and Co-10Al-5W-2Ta, which suggests that its γ ′ phase stoichiometry is less constrained. A possible correlation between temperature and misfit normalised r vs. t 1/3 coarsening rate coefficients and the structural gradient width has also been identified, whereby alloys with wider interfaces exhibit faster coarsening rates.

  10. Dendritic coarsening of γ' phase in a directionally solidified superalloy during 24,000 h of exposure at 1173 K

    International Nuclear Information System (INIS)

    Li, H.; Wang, L.; Lou, L.H.

    2010-01-01

    Dendritic coarsening of γ' was investigated in a directionally solidified Ni-base superalloy during exposure at 1173 K for 24,000 h. Chemical homogeneity along different directions and residual internal strain in the experimental superalloy were measured by electronic probe microanalysis (EPMA) and electron back-scattered diffraction (EBSD) technique. It was indicated that the gradient of element distribution was anisotropic and the inner strain between dendrite core and interdendritic regions was different even after 24,000 h of exposure at 1173 K, which influenced the kinetics for the dendrite coarsening of γ' phase.

  11. Recent coarsening of sediments on the southern Yangtze subaqueous delta front: A response to river damming

    Science.gov (United States)

    Yang, H. F.; Yang, S. L.; Meng, Y.; Xu, K. H.; Luo, X. X.; Wu, C. S.; Shi, B. W.

    2018-03-01

    After more than 50,000 dams were built in the Yangtze basin, especially the Three Gorges Dam (TGD) in 2003, the sediment discharge to the East China Sea decreased from 470 Mt/yr before dams to the current level of 140 Mt/yr. The delta sediment's response to this decline has interested many researchers. Based on a dataset of repeated samplings at 44 stations in this study, we compared the surficial sediment grain sizes in the southern Yangtze subaqueous delta front for two periods: pre-TGD (1982) and post-TGD (2012). External factors of the Yangtze River, including water discharge, sediment discharge and suspended sediment grain size, were analysed, as well as wind speed, tidal range and wave height of the coastal ocean. We found that the average median size of the sediments in the delta front coarsened from 8.0 μm in 1982 to 15.4 μm in 2012. This coarsening was accompanied by a decrease of clay components, better sorting and more positive skewness. Moreover, the delta morphology in the study area changed from an overall accretion of 1.0 cm/yr to an erosion of - 0.6 cm/yr. At the same time, the riverine sediment discharge decreased by 70%, and the riverine suspended sediment grain size increased from 8.4 μm to 10.5 μm. The annual wind speed and wave height slightly increased by 2% and 3%, respectively, and the tidal range showed no change trend. Considering the increased wind speed and wave height, there was no evidence that the capability of the China Coastal Current to transport sediment southward has declined in recent years. The sediment coarsening in the Yangtze delta front was thus mainly attributed to the delta's transition from accumulation to erosion which was originally generated by river damming. These findings have important implications for sediment change in many large deltaic systems due to worldwide human impacts.

  12. On weighted hardy inequalities on semiaxis for functions vanishing at the endpoints

    Directory of Open Access Journals (Sweden)

    Stepanov Vladimir

    1997-01-01

    Full Text Available We study the weighted Hardy inequalities on the semiaxis of the form for functions vanishing at the endpoints together with derivatives up to the order . The case is completely characterized.

  13. Vanishing points detection using combination of fast Hough transform and deep learning

    Science.gov (United States)

    Sheshkus, Alexander; Ingacheva, Anastasia; Nikolaev, Dmitry

    2018-04-01

    In this paper we propose a novel method for vanishing points detection based on convolutional neural network (CNN) approach and fast Hough transform algorithm. We show how to determine fast Hough transform neural network layer and how to use it in order to increase usability of the neural network approach to the vanishing point detection task. Our algorithm includes CNN with consequence of convolutional and fast Hough transform layers. We are building estimator for distribution of possible vanishing points in the image. This distribution can be used to find candidates of vanishing point. We provide experimental results from tests of suggested method using images collected from videos of road trips. Our approach shows stable result on test images with different projective distortions and noise. Described approach can be effectively implemented for mobile GPU and CPU.

  14. The vanishing twin: a major determinant of infant outcome in IVF singleton births

    DEFF Research Database (Denmark)

    Pinborg, Anja; Lidegaard, Ojvind; Andersen, Anders Nyboe

    2006-01-01

    This article attempts to assess the frequency of vanishing twins in assisted reproductive and spontaneously conceived pregnancies, including in-vitro fertilization (IVF), and its impact on the live-born surviving twin.......This article attempts to assess the frequency of vanishing twins in assisted reproductive and spontaneously conceived pregnancies, including in-vitro fertilization (IVF), and its impact on the live-born surviving twin....

  15. When Dijkstra Meets Vanishing Point: A Stereo Vision Approach for Road Detection.

    Science.gov (United States)

    Zhang, Yigong; Su, Yingna; Yang, Jian; Ponce, Jean; Kong, Hui

    2018-05-01

    In this paper, we propose a vanishing-point constrained Dijkstra road model for road detection in a stereo-vision paradigm. First, the stereo-camera is used to generate the u- and v-disparity maps of road image, from which the horizon can be extracted. With the horizon and ground region constraints, we can robustly locate the vanishing point of road region. Second, a weighted graph is constructed using all pixels of the image, and the detected vanishing point is treated as the source node of the graph. By computing a vanishing-point constrained Dijkstra minimum-cost map, where both disparity and gradient of gray image are used to calculate cost between two neighbor pixels, the problem of detecting road borders in image is transformed into that of finding two shortest paths that originate from the vanishing point to two pixels in the last row of image. The proposed approach has been implemented and tested over 2600 grayscale images of different road scenes in the KITTI data set. The experimental results demonstrate that this training-free approach can detect horizon, vanishing point, and road regions very accurately and robustly. It can achieve promising performance.

  16. The effect of β grain coarsening on variant selection and texture evolution in a near-β Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Obasi, G.C; Quinta da Fonseca, J. [Manchester Materials Science Centre, The University of Manchester, Grosvenor street, Manchester M13 9PL (United Kingdom); Rugg, D. [Rolls-Royce plc, P.O. Box 31, Derby DE24 8BJ (United Kingdom); Preuss, M., E-mail: michael.preuss@manchester.ac.uk [Manchester Materials Science Centre, The University of Manchester, Grosvenor street, Manchester M13 9PL (United Kingdom)

    2013-08-01

    In the present study, the role of β grain coarsening on α variant selection has been investigated in the near-titanium alloy Ti–21S (Ti–15Mo–3Nb–3Al–0.21Si). The material was first thermomechanically processed in a fully β stabilised condition in order to obtain a fine β grain size before undertaking controlled β grain-coarsening heat treatments. Two different cooling regimes ensured that either all β was retained at room temperature or significant α formation was achieved during cooling with predominant nucleation from β grain boundaries. Detailed electron backscatter diffraction (EBSD) characterisation was carried out on the β quenched and slowly cooled samples in order to compare the predicted α texture based on the β texture measurements assuming no variant selection with the measured α textures. A strong correlation was found between β coarsening and level of variant selection. It was also found that the grain coarsening is driven by the predominant growth of low energy grain boundaries, which strengthen specific β texture components that are part of the 〈1 1 1〉∥ND γ fibre. Finally, it was possible to demonstrate that the strengthened β texture components promote β grain pairs with a common 〈110〉, which is known to enhance variant selection when α nucleates from β grain boundaries.

  17. Generalization of the Lifshitz-Slyozov-Wagner coarsening theory to non-dilute multi-component systems

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; Fischer, F. D.

    2014-01-01

    Roč. 79, OCT (2014), s. 304-314 ISSN 1359-6454 R&D Projects: GA ČR(CZ) GA14-24252S Institutional support: RVO:68081723 Keywords : Coarsening * Ostwald ripening * Multicomponent * Theory and modelling * Non-zero volume fraction of precipitates Subject RIV: BJ - Thermodynamics Impact factor: 4.465, year: 2014

  18. The evolution of interfacial morphology during coarsening: A comparison between 4D experiments and phase-field simulations

    DEFF Research Database (Denmark)

    Aagesen, L.K.; Fife, J.L.; Lauridsen, Erik Mejdal

    2011-01-01

    The evolution of the solid–liquid interface in an Al–Cu dendritic microstructure is predicted using a phase-field model and compared to experimental data. The interfacial velocities are measured during isothermal coarsening using in situ X-ray tomographic microscopy. Good qualitative agreement...

  19. Coarsening of Ni-Ge solid-solution precipitates in 'inverse' Ni{sub 3}Ge alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ardell, Alan J., E-mail: alan.ardell@gmail.com [National Science Foundation, 4201 Wilson Boulevard, Arlington, VA 22230 (United States); Ma Yong [Aquatic Sensor Network Technology LLC, Storrs, CT 06268 (United States)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer We report microstructural evolution of disordered Ni-Ge precipitates in Ni{sub 3}Ge alloys. Black-Right-Pointing-Pointer Coarsening kinetics and particle size distributions are presented. Black-Right-Pointing-Pointer Data are analyzed quantitatively using the MSLW theory, but agreement is only fair. Black-Right-Pointing-Pointer The shapes of large precipitates are unusual, with discus or boomerang cross-sections. Black-Right-Pointing-Pointer Results are compared with morphology, kinetics of Ni-Al in inverse Ni{sub 3}Al alloys. - Abstract: The morphological evolution and coarsening kinetics of Ni-Ge solid solution precipitates from supersaturated solutions of hypostoichiometric Ni{sub 3}Ge were investigated in alloys containing from 22.48 to 23.50 at.% Ge at 600, 650 and 700 Degree-Sign C. The particles evolve from spheres to cuboids, though the flat portions of the interfaces are small. At larger sizes the precipitates coalesce into discus shapes, and are sometimes boomerang-shaped in cross section after intersection. The rate constant for coarsening increases strongly with equilibrium volume fraction, much more so than predicted by current theories; this is very different from the coarsening behavior of Ni{sub 3}Ge precipitates in normal Ni-Ge alloys and of Ni-Al precipitates in inverse Ni{sub 3}Al alloys. The activation energy for coarsening, 275.86 {+-} 24.17 kJ/mol, is somewhat larger than the result from conventional diffusion experiments, though within the limits of experimental error. Quantitative agreement between theory and experiment, estimated using available data on tracer diffusion coefficients in Ni{sub 3}Ge, is fair, the calculated rate constants exceeding measured ones by a factor of about 15. The particle size distributions are not in very good agreement with the predictions of any theory. These results are discussed in the context of recent theories and observations.

  20. Coarsening of Ni–Ge solid-solution precipitates in “inverse” Ni3Ge alloys

    International Nuclear Information System (INIS)

    Ardell, Alan J.; Ma Yong

    2012-01-01

    Highlights: ► We report microstructural evolution of disordered Ni–Ge precipitates in Ni 3 Ge alloys. ► Coarsening kinetics and particle size distributions are presented. ► Data are analyzed quantitatively using the MSLW theory, but agreement is only fair. ► The shapes of large precipitates are unusual, with discus or boomerang cross-sections. ► Results are compared with morphology, kinetics of Ni–Al in inverse Ni 3 Al alloys. - Abstract: The morphological evolution and coarsening kinetics of Ni–Ge solid solution precipitates from supersaturated solutions of hypostoichiometric Ni 3 Ge were investigated in alloys containing from 22.48 to 23.50 at.% Ge at 600, 650 and 700 °C. The particles evolve from spheres to cuboids, though the flat portions of the interfaces are small. At larger sizes the precipitates coalesce into discus shapes, and are sometimes boomerang-shaped in cross section after intersection. The rate constant for coarsening increases strongly with equilibrium volume fraction, much more so than predicted by current theories; this is very different from the coarsening behavior of Ni 3 Ge precipitates in normal Ni–Ge alloys and of Ni–Al precipitates in inverse Ni 3 Al alloys. The activation energy for coarsening, 275.86 ± 24.17 kJ/mol, is somewhat larger than the result from conventional diffusion experiments, though within the limits of experimental error. Quantitative agreement between theory and experiment, estimated using available data on tracer diffusion coefficients in Ni 3 Ge, is fair, the calculated rate constants exceeding measured ones by a factor of about 15. The particle size distributions are not in very good agreement with the predictions of any theory. These results are discussed in the context of recent theories and observations.

  1. Nonlinear waves in plasma with negative ion

    International Nuclear Information System (INIS)

    Saito, Maki; Watanabe, Shinsuke; Tanaca, Hiroshi.

    1984-01-01

    The propagation of nonlinear ion wave is investigated theoretically in a plasma with electron, positive ion and negative ion. The ion wave of long wavelength is described by a modified K-dV equation instead of a K-dV equation when the nonlinear coefficient of the K-dV equation vanishes at the critical density of negative ion. In the vicinity of the critical density, the ion wave is described by a coupled K-dV and modified K-dV equation. The transition from a compressional soliton to a rarefactive soliton and vice versa are examined by the coupled equation as a function of the negative ion density. The ion wave of short wavelength is described by a nonlinear Schroedinger equation. In the plasma with a negative ion, the nonlinear coefficient of the nonlinear Schroedinger equation changes the sign and the ion wave becomes modulationally unstable. (author)

  2. Polynomially decaying transmission for the nonlinear schrodinger equation in a random medium

    International Nuclear Information System (INIS)

    Devillard, P.; Sovillard, B.

    1986-01-01

    This is the first study of one the transmission problems associate to the nonlinear Schrodinger equation with a random potential. We show that for almost every realization of the medium the rate of transmission vanishes when increasing the size of the medium; however, whereas it decays exponentially in the linear regime, it decays polynomially in the nonlinear one

  3. Giant Kerr nonlinearities using refractive-index enhancement

    International Nuclear Information System (INIS)

    Yavuz, D. D.; Sikes, D. E.

    2010-01-01

    By utilizing refractive-index enhancement with vanishing absorption, a scheme is suggested that achieves giant Kerr nonlinearities between two weak laser beams. One application of this scheme is discussed and an all-optical distributed Bragg reflector is proposed that works at very low light levels.

  4. Hodgkin's lymphoma-related vanishing bile duct syndrome: A case report and literature review

    Directory of Open Access Journals (Sweden)

    Kiong-Ming Wong

    2013-11-01

    Full Text Available We report the case of a 38-year-old man who developed vanishing bile duct syndrome in association with Hodgkin's lymphoma. He was noted to have cervical lymphadenopathy and marked elevation of total serum bilirubin at diagnosis. He achieved complete remission with normalization of serum bilirubin after eight courses of Adriamycin, bleomycin, vinblastine, and dacarbazine chemotherapy followed with autologous hematopoietic cell transplantation. Consecutive liver biopsies performed at diagnosis and at the stage of complete remission revealed the disappearance and regeneration of interlobular bile ducts, respectively. Our case provides pathological evidence that Hodgkin's lymphoma-related vanishing bile duct syndrome is a reversible bile duct injury disease. Bilirubin is a reliable serum marker to monitor the treatment response of these cases. The mechanism to develop hyperbilirubinemia with vanishing bile duct in such a case of Hodgkin's lymphoma remains to be studied. A literature review was carried out.

  5. So It Vanished: Art, Taboo and Shared Space in Contemporary Aotearoa New Zealand

    Directory of Open Access Journals (Sweden)

    Jonathan Barrett

    2013-04-01

    Full Text Available In February 2012, The Dowse Art Museum in Lower Hutt, near Wellington, planned to host So It Vanishes, an exhibition by acclaimed Mexican artist Teresa Margolles, whose often shocking works seek to highlight how dispensable human life has become in the parts of Mexico riven by drugs wars. Margolles’s installation would have used infinitesimal amounts of morgue water in a bubble mixture dispensed into an empty, silent room in the same building that sacred Māori treasures are housed. The incorporation of water used to wash corpses in So It Vanishes, particularly in proximity to cultural treasures, would have been deeply offensive, indeed dangerous, for Māori people. Following objections, the exhibition was cancelled. This article analyses the cancellation of So It Vanishes and seeks to answer whether and how transgressive art and indigenous beliefs may be reconciled in contemporary Aotearoa New Zealand.

  6. Toward Small-Diameter Carbon Nanotubes Synthesized from Captured Carbon Dioxide: Critical Role of Catalyst Coarsening.

    Science.gov (United States)

    Douglas, Anna; Carter, Rachel; Li, Mengya; Pint, Cary L

    2018-05-23

    Small-diameter carbon nanotubes (CNTs) often require increased sophistication and control in synthesis processes, but exhibit improved physical properties and greater economic value over their larger-diameter counterparts. Here, we study mechanisms controlling the electrochemical synthesis of CNTs from the capture and conversion of ambient CO 2 in molten salts and leverage this understanding to achieve the smallest-diameter CNTs ever reported in the literature from sustainable electrochemical synthesis routes, including some few-walled CNTs. Here, Fe catalyst layers are deposited at different thicknesses onto stainless steel to produce cathodes, and atomic layer deposition of Al 2 O 3 is performed on Ni to produce a corrosion-resistant anode. Our findings indicate a correlation between the CNT diameter and Fe metal layer thickness following electrochemical catalyst reduction at the cathode-molten salt interface. Further, catalyst coarsening during long duration synthesis experiments leads to a 2× increase in average diameters from 3 to 60 min durations, with CNTs produced after 3 min exhibiting a tight diameter distribution centered near ∼10 nm. Energy consumption analysis for the conversion of CO 2 into CNTs demonstrates energy input costs much lower than the value of CNTs-a concept that strictly requires and motivates small-diameter CNTs-and is more favorable compared to other costly CO 2 conversion techniques that produce lower-value materials and products.

  7. Structure and coarsening at the surface of a dry three-dimensional aqueous foam.

    Science.gov (United States)

    Roth, A E; Chen, B G; Durian, D J

    2013-12-01

    We utilize total-internal reflection to isolate the two-dimensional surface foam formed at the planar boundary of a three-dimensional sample. The resulting images of surface Plateau borders are consistent with Plateau's laws for a truly two-dimensional foam. Samples are allowed to coarsen into a self-similar scaling state where statistical distributions appear independent of time, except for an overall scale factor. There we find that statistical measures of side number distributions, size-topology correlations, and bubble shapes are all very similar to those for two-dimensional foams. However, the size number distribution is slightly broader, and the shapes are slightly more elongated. A more obvious difference is that T2 processes now include the creation of surface bubbles, due to rearrangement in the bulk, and von Neumann's law is dramatically violated for individual bubbles. But nevertheless, our most striking finding is that von Neumann's law appears to holds on average, namely, the average rate of area change for surface bubbles appears to be proportional to the number of sides minus six, but with individual bubbles showing a wide distribution of deviations from this average behavior.

  8. The coarsening effect of SA508-3 steel used as heavy forgings material

    Directory of Open Access Journals (Sweden)

    Dingqian Dong

    2015-01-01

    Full Text Available SA508Gr.3 steel is popularly used to produce core unit of nuclear power reactors due to its outstanding ability of anti-neutron irradiation and good fracture toughness. The forging process takes important role in manufacturing to refine the grain size and improve the material properties. But due to their huge size, heavy forgings cannot be cooled down quickly, and the refined grains usually have long time to grow in high temperature conditions. If the forging process is not adequately scheduled or implemented, very large grains up to millimetres in size may be found in this steel and cannot be eliminated in the subsequent heat treatment. To fix the condition which may causes the coarsening of the steel, hot upsetting experiments in the industrial production environment were performed under different working conditions and the corresponding grain sizes were measured and analysed. The observation showed that the grain will abnormally grow if the deformation is less than a critical value. The strain energy takes a critical role in the grain evolution. If dynamic recrystallization consumes the strain energy as much as possible, the normal grains will be obtained. While if not, the stored strain energy will promote abnormal growth of the grains.

  9. Coarsening and pattern formation during true morphological phase separation in unstable thin films under gravity

    Science.gov (United States)

    Kumar, Avanish; Narayanam, Chaitanya; Khanna, Rajesh; Puri, Sanjay

    2017-12-01

    We address in detail the problem of true morphological phase separation (MPS) in three-dimensional or (2 +1 )-dimensional unstable thin liquid films (>100 nm) under the influence of gravity. The free-energy functionals of these films are asymmetric and show two points of common tangency, which facilitates the formation of two equilibrium phases. Three distinct patterns formed by relative preponderance of these phases are clearly identified in "true MPS". Asymmetricity induces two different pathways of pattern formation, viz., defect and direct pathway for true MPS. The pattern formation and phase-ordering dynamics have been studied using statistical measures such as structure factor, correlation function, and growth laws. In the late stage of coarsening, the system reaches into a scaling regime for both pathways, and the characteristic domain size follows the Lifshitz-Slyozov growth law [L (t ) ˜t1 /3] . However, for the defect pathway, there is a crossover of domain growth behavior from L (t ) ˜t1 /4→t1 /3 in the dynamical scaling regime. We also underline the analogies and differences behind the mechanisms of MPS and true MPS in thin liquid films and generic spinodal phase separation in binary mixtures.

  10. Modeling of the influence of coarsening on viscoplastic behavior of a 319 foundry aluminum alloy

    International Nuclear Information System (INIS)

    Martinez, R.; Russier, V.; Couzinié, J.P.; Guillot, I.; Cailletaud, G.

    2013-01-01

    Both metallurgical and mechanical behaviors of a 319 foundry aluminum alloy have been modeled by means of a multiscale approach. The nano-scale, represented by the coarsening of Al 2 Cu precipitates, has been modeled according to the Lifshitz–Slyozov–Wagner (LSW) law in a range of temperature going from 23 °C to 300 °C up to 1000 h aging time. Results were then compared to transmission electron microscope (TEM) observations and are in good agreement with the experimental measurements. The model allows us to know the critical radius, the volume fraction and the number of particles per μm 3 in a α-phase representative volume element (RVE). The increase in yield stress generated by the interaction of dislocations with precipitates, lattice and solid solution, is modeled on the microscale. The yield stress becomes thus a function of the precipitation state, and is time/temperature dependent. These two models were then combined into a mechanical macroscale model in order to represent the Low Cycle Fatigue (LCF) behavior of the material. An elasto-viscoplastic law has been used and all the material parameters were experimentally determined with LCF stress/strain loops for the first cycle and for the mechanical steady state. The simulation results are in good agreement with the experiments.

  11. The effects of size, clutter, and complexity on vanishing-point distances in visual imagery.

    Science.gov (United States)

    Hubbard, T L; Baird, J C

    1993-01-01

    The portrayal of vanishing-point distances in visual imagery was examined in six experiments. In all experiments, subjects formed visual images of squares, and the squares were to be oriented orthogonally to subjects' line of sight. The squares differed in their level of surface complexity, and were either undivided, divided into 4 equally sized smaller squares, or divided into 16 equally sized smaller squares. Squares also differed in stated referent size, and ranged from 3 in. to 128 ft along each side. After subjects had formed an image of a specified square, they transformed their image so that the square was portrayed to move away from them. Eventually, the imaged square was portrayed to be so far away that if it were any further away, it could not be identified. Subjects estimated the distance to the square that was portrayed in their image at that time, the vanishing-point distance, and the relationship between stated referent size and imaged vanishing-point distance was best described by a power function with an exponent less than 1. In general, there were trends for exponents (slopes on log axes) to increase slightly and for multiplicative constants (y intercepts on log axes) to decrease as surface complexity increased. No differences in exponents or in multiplicative constants were found when the vanishing-point was approached from either subthreshold or suprathreshold directions. When clutter in the form of additional imaged objects located to either side of the primary imaged object was added to the image, the exponent of the vanishing-point function increased slightly and the multiplicative constant decreased. The success of a power function (and the failure of the size-distance invariance hypothesis) in describing the vanishing-point distance function calls into question the notions (a) that a constant grain size exists in the imaginal visual field at a given location and (b) that grain size specifies a lower limit in the storage of information in

  12. Measuring laves phase particle size and thermodynamic calculating its growth and coarsening behavior in P92 steels

    DEFF Research Database (Denmark)

    Yao, Bing-Yin; Zhou, Rong-Can; Fan, Chang-Xin

    2010-01-01

    The growth of Laves phase particles in three kinds of P92 steels were investigated. Laves phase particles can be easily separated and distinguished from the matrix and other particles by atom number contrast using comparisons of the backscatter electrons (BSE) images and the secondary electrons (SE......) images in scanning electron microscope (SEM). The smaller Laves phase particle size results in higher creep strength and longer creep exposure time at the same conditions. DICTRA software was used to model the growth and coarsening behavior of Laves phase in the three P92 steels. Good agreements were...... attained between measurements in SEM and modeling by DICTRA. Ostwald ripening should be used for the coarsening calculation of Laves phase in P92 steels for time longer than 20000 h and 50000 h at 650°C and 600°C, respectively. © 2010 Chin. Soc. for Elec. Eng....

  13. An application of stress energy tensor to the vanishing theorem of differential forms

    Directory of Open Access Journals (Sweden)

    Kairen Cai

    1988-01-01

    Full Text Available The author applies the stress energy of differential forms to study the vanishing theorems of the Liouville type. It is shown that for a large class of underlying manifolds such as the Euclidean n-space, the complex n-space, and the complex hyperbolic space form, if any vector bundle valued p-form with conservative stress energy tensor is of finite norm or slowly divergent norm, then the p-form vanishes. This generalizes the recent results due to Hu and Sealey.

  14. Non-vanishing of Taylor coefficients and Poincaré series

    DEFF Research Database (Denmark)

    O'Sullivan, C.; Risager, Morten S.

    2013-01-01

    We prove recursive formulas for the Taylor coefficients of cusp forms, such as Ramanujan's Delta function, at points in the upper half-plane. This allows us to show the non-vanishing of all Taylor coefficients of Delta at CM points of small discriminant as well as the non-vanishing of certain...... Poincaré series. At a "generic" point, all Taylor coefficients are shown to be non-zero. Some conjectures on the Taylor coefficients of Delta at CM points are stated....

  15. Variational Iteration Method for Volterra Functional Integrodifferential Equations with Vanishing Linear Delays

    Directory of Open Access Journals (Sweden)

    Ali Konuralp

    2014-01-01

    Full Text Available Application process of variational iteration method is presented in order to solve the Volterra functional integrodifferential equations which have multi terms and vanishing delays where the delay function θ(t vanishes inside the integral limits such that θ(t=qt for 0

  16. Enhancement of multiple cranial and spinal nerves in vanishing white matter: expanding the differential diagnosis.

    Science.gov (United States)

    Eluvathingal Muttikkal, Thomas Jose; Montealegre, Denia Ramirez; Matsumoto, Julie Ann

    2018-03-01

    Abnormal cranial or spinal nerve contrast enhancement on MRI in cases of suspected pediatric leukodystrophy is recognized as an important clue to the diagnosis of either metachromatic leukodystrophy or globoid cell leukodystrophy (Krabbe disease). We report a case of genetically confirmed childhood vanishing white matter with enhancement of multiple cranial and spinal nerves in addition to the more typical intracranial findings. This case expands the limited differential diagnosis of cranial nerve or spinal nerve enhancement in cases of suspected leukodystrophy and may aid in more efficient work-up and earlier diagnosis of vanishing white matter.

  17. The investigation of abnormal particle-coarsening phenomena in friction stir repair weld of 2219-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Li, Bo; Shen, Yifu

    2011-01-01

    Highlights: → Defective friction stir welds were repaired by overlapping FSW technique. → Abnormal Al 2 Cu-coarsening phenomena were found in 2219-T6 friction stir repair weld. → Three formation mechanisms were proposed for reasonable explanations. -- Abstract: The single-pass friction stir weld of aluminum 2219-T6 with weld-defects was repaired by overlapping friction stir welding technique. However, without any post weld heat treatment process, it was found that the phenomena of abnormal particle-coarsening of Al 2 Cu had occurred in the overlapping friction stir repair welds. The detecting results of non-destructive X-ray inspection proved that not only one group of repair FSW process parameters could lead to occurrence of the abnormal phenomena. And the abnormally coarsened particles always appeared on the advancing side of repair welds rather than the retreating side where the fracture behaviors occurred after mechanical tensile testing. The size of the biggest particle lying in the dark bands of 'Onion-rings' was more than 150 μm. After the related investigation by scanning electron microscope and X-ray energy spectrometer, three types of formation mechanisms were proposed for reasonably explaining the abnormal phenomenon: Aggregation Mechanism, Diffusion Mechanisms I and II. Aggregation Mechanism was according to the motion-laws of stir-pin. Diffusion Mechanisms were based on the classical theories of precipitate growth in metallic systems. The combined action of the three detailed mechanisms contributed to the abnormal coarsening behavior of Al 2 Cu particles in the friction stir repair weld.

  18. Study of phase decomposition and coarsening of γ′ precipitates in Ni-12 at.% Ti alloy

    International Nuclear Information System (INIS)

    Garay-Reyes, C.G.; Hernández-Santiago, F.; Cayetano-Castro, N.; López-Hirata, V.M.; García-Rocha, J.; Hernández-Rivera, J.L.; Dorantes-Rosales, H.J.; Cruz-Rivera, J.J.

    2013-01-01

    The early stages of phase decomposition, morphological evolution of precipitates, coarsening kinetics of γ′ precipitates and micro-hardness in Ni-12 at.% Ti alloy are studied by transmission electron microscopy (TEM) and Vickers hardness tests (VHN). Disk-shaped specimens are solution treated at 1473 K (1200 °C) and aged at 823, 923 and 1023 K (550, 650 and 750 °C) during several periods of time. TEM results show that a conditional spinodal of order occurs at the beginning of the phase decomposition and exhibit the following decomposition sequence and morphological evolution of precipitates: α sss → γ″ irregular–cuboidal + γ s → γ′ cuboidal–parallelepiped + γ → η plates + γ. In general during the coarsening of γ′ precipitates, the experimental coarsening kinetics do not fit well to the LSW or TIDC (n = 2.281) theoretical models, however the activation energies determined using the TIDC and LSW theories (262.846 and 283.6075 kJ mol −1 , respectively) are consistent with previously reported values. The highest hardness obtained at 823, 923 and 1023 K (550, 650 and 750 °C) is associated with the presence of γ′ precipitates. - Highlights: • It was studied the conditional spinodal during early stages of phase decomposition. • It was obtained decomposition sequence and morphological evolution of precipitates. • It was experimentally evaluated the coarsening kinetics of γ′ precipitates. • The maximum hardness is associated with the γ′ precipitates

  19. Study of phase decomposition and coarsening of γ′ precipitates in Ni-12 at.% Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Garay-Reyes, C.G., E-mail: garay_820123@hotmail.com [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra leona 550, Col. Lomas 2 sección, 78210 S.L.P. (Mexico); Hernández-Santiago, F. [Instituto Politécnico Nacional, ESIME-AZC, Av. de las Granjas 682, col. Sta. Catarina, 02550 D.F. (Mexico); Cayetano-Castro, N. [Instituto Potosino de Investigación Científica y Tecnológica, División de Materiales Avanzados, camino a la Presa San José 2055, Col Lomas 4 sección, 78216 S.L.P. (Mexico); López-Hirata, V.M. [Instituto Politécnico Nacional, ESIQIE-DIM, 118-556, D.F. (Mexico); García-Rocha, J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra leona 550, Col. Lomas 2 sección, 78210 S.L.P. (Mexico); Hernández-Rivera, J.L. [Centro de Investigación de Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua (Mexico); Dorantes-Rosales, H.J. [Instituto Politécnico Nacional, ESIQIE-DIM, 118-556, D.F. (Mexico); Cruz-Rivera, J.J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra leona 550, Col. Lomas 2 sección, 78210 S.L.P. (Mexico)

    2013-09-15

    The early stages of phase decomposition, morphological evolution of precipitates, coarsening kinetics of γ′ precipitates and micro-hardness in Ni-12 at.% Ti alloy are studied by transmission electron microscopy (TEM) and Vickers hardness tests (VHN). Disk-shaped specimens are solution treated at 1473 K (1200 °C) and aged at 823, 923 and 1023 K (550, 650 and 750 °C) during several periods of time. TEM results show that a conditional spinodal of order occurs at the beginning of the phase decomposition and exhibit the following decomposition sequence and morphological evolution of precipitates: α{sub sss} → γ″ irregular–cuboidal + γ{sub s} → γ′ cuboidal–parallelepiped + γ → η plates + γ. In general during the coarsening of γ′ precipitates, the experimental coarsening kinetics do not fit well to the LSW or TIDC (n = 2.281) theoretical models, however the activation energies determined using the TIDC and LSW theories (262.846 and 283.6075 kJ mol{sup −1}, respectively) are consistent with previously reported values. The highest hardness obtained at 823, 923 and 1023 K (550, 650 and 750 °C) is associated with the presence of γ′ precipitates. - Highlights: • It was studied the conditional spinodal during early stages of phase decomposition. • It was obtained decomposition sequence and morphological evolution of precipitates. • It was experimentally evaluated the coarsening kinetics of γ′ precipitates. • The maximum hardness is associated with the γ′ precipitates.

  20. Application of a multi-component mean field model to the coarsening behaviour of a nickel-based superalloy

    International Nuclear Information System (INIS)

    Anderson, M.J.; Rowe, A.; Wells, J.; Basoalto, H.C.

    2016-01-01

    A multi-component mean field model has been applied to predict the particle evolution of the γ′ particles in the nickel based superalloy IN738LC, capturing the transition from an initial multimodal particle distribution towards a unimodal distribution. Experiments have been performed to measure the coarsening behaviour during isothermal heat treatments using quantitative analysis of micrographs. The three dimensional size of the γ′ particles has been approximated for use in simulation. A coupled thermodynamic/mean field modelling framework is presented and applied to describe the particle size evolution. A robust numerical implementation of the model is detailed that makes use of surrogate models to capture the thermodynamics. Different descriptions of the particle growth rate of non-dilute particle systems have been explored. A numerical investigation of the influence of scatter in chemical composition upon the particle size distribution evolution has been carried out. It is shown how the tolerance in chemical composition of a given alloy can impact particle coarsening behaviour. Such predictive capability is of interest in understanding variation in component performance and the refinement of chemical composition tolerances. It has been found that the inclusion of misfit strain within the current model formulation does not have a significant affect upon predicted long term particle coarsening behaviour. Model predictions show good agreement with experimental data. In particular, the model predicts a reduced growth rate of the mean particle size during the transition from bimodal to unimodal distributions.

  1. Three dimensional characterization of nickel coarsening in solid oxide cells via ex-situ ptychographic nano-tomography

    Science.gov (United States)

    De Angelis, Salvatore; Jørgensen, Peter Stanley; Tsai, Esther Hsiao Rho; Holler, Mirko; Kreka, Kosova; Bowen, Jacob R.

    2018-04-01

    Nickel coarsening is considered a significant cause of solid oxide cell (SOC) performance degradation. Therefore, understanding the morphological changes in the nickel-yttria stabilized zirconia (Ni-YSZ) fuel electrode is crucial for the wide spread usage of SOC technology. This paper reports a study of the initial 3D microstructure evolution of a SOC analyzed in the pristine state and after 3 and 8 h of annealing at 850 °C, in dry hydrogen. The analysis of the evolution of the same location of the electrode shows a substantial change of the nickel and pore network during the first 3 h of treatment, while only negligible changes are observed after 8 h. The nickel coarsening results in loss of connectivity in the nickel network, reduced nickel specific surface area and decreased total triple phase boundary density. For the condition of this experiment, nickel coarsening is shown to be predominantly curvature driven, and changes in the electrode microstructure parameters are discussed in terms of local microstructural evolution.

  2. Unusual case of a vanishing bronchus of the left allograft in a lung transplant recipient

    Directory of Open Access Journals (Sweden)

    Don Hayes

    2013-01-01

    Full Text Available We present an interesting case of a complete vanishing of the left main bronchus in a lung transplant recipient who had a successful outcome due to acute respiratory support with venovenous extracorporeal membrane oxygenation in order to perform airway dilation.

  3. VANISHING CALCIFICATION OF THE BRAIN IN AN INFANT AFTER OPEN-HEART-SURGERY

    NARCIS (Netherlands)

    BEGEER, JH; RUTGERS, AWF; VENCKEN, LM; HOORNTJE, TM; MEUZELAAR, JJ; WOLTERSOMZWIERZYNSKA, BD

    1991-01-01

    Neurological complications after cardiac operations with the aid of cardiopulmonary bypass and hypothermia are well known. A 6 months-old child is described with severe neurological complications after cardiac surgery for Fallots tetralogy. On the CT scan cortical calcification was seen to vanish.

  4. Vanishing quantum vacuum energy in eleven-dimensional supergravity on the round seven-sphere

    International Nuclear Information System (INIS)

    Inami, T.; Yamagishi, K.

    1984-01-01

    Quantum corrections to the vacuum energy are evaluated at one-loop order in eleven-dimensional supergravity on the round seven-sphere S 7 and are shown to vanish. The cancellation is also shown for all ultraviolet poles at z = 11/2, 10/2,..., corresponding to divergences of eleventh and lower powers of momentum cut-off Λ. (orig.)

  5. Local invariants vanishing on stationary horizons: a diagnostic for locating black holes.

    Science.gov (United States)

    Page, Don N; Shoom, Andrey A

    2015-04-10

    Inspired by the example of Abdelqader and Lake for the Kerr metric, we construct local scalar polynomial curvature invariants that vanish on the horizon of any stationary black hole: the squared norms of the wedge products of n linearly independent gradients of scalar polynomial curvature invariants, where n is the local cohomogeneity of the spacetime.

  6. Spectral properties of a confined nonlinear quantum oscillator in one and three dimensions

    International Nuclear Information System (INIS)

    Schulze-Halberg, Axel; Gordon, Christopher R.

    2013-01-01

    We analyze the spectral behaviour of a nonlinear quantum oscillator model under confinement. The underlying potential is given by a harmonic oscillator interaction plus a nonlinear term that can be weakened or strengthened through a parameter. Numerical eigenvalues of the model in one and three dimensions are presented. The asymptotic behaviour of the eigenvalues for confinement relaxation and for vanishing nonlinear term in the potential is investigated. Our findings are compared with existing results.

  7. Nonlinear optics

    International Nuclear Information System (INIS)

    Boyd, R.W.

    1992-01-01

    Nonlinear optics is the study of the interaction of intense laser light with matter. This book is a textbook on nonlinear optics at the level of a beginning graduate student. The intent of the book is to provide an introduction to the field of nonlinear optics that stresses fundamental concepts and that enables the student to go on to perform independent research in this field. This book covers the areas of nonlinear optics, quantum optics, quantum electronics, laser physics, electrooptics, and modern optics

  8. Nonlinear dynamics and anisotropic structure of rotating sheared turbulence.

    Science.gov (United States)

    Salhi, A; Jacobitz, F G; Schneider, K; Cambon, C

    2014-01-01

    Homogeneous turbulence in rotating shear flows is studied by means of pseudospectral direct numerical simulation and analytical spectral linear theory (SLT). The ratio of the Coriolis parameter to shear rate is varied over a wide range by changing the rotation strength, while a constant moderate shear rate is used to enable significant contributions to the nonlinear interscale energy transfer and to the nonlinear intercomponental redistribution terms. In the destabilized and neutral cases, in the sense of kinetic energy evolution, nonlinearity cannot saturate the growth of the largest scales. It permits the smallest scale to stabilize by a scale-by-scale quasibalance between the nonlinear energy transfer and the dissipation spectrum. In the stabilized cases, the role of rotation is mainly nonlinear, and interacting inertial waves can affect almost all scales as in purely rotating flows. In order to isolate the nonlinear effect of rotation, the two-dimensional manifold with vanishing spanwise wave number is revisited and both two-component spectra and single-point two-dimensional energy components exhibit an important effect of rotation, whereas the SLT as well as the purely two-dimensional nonlinear analysis are unaffected by rotation as stated by the Proudman theorem. The other two-dimensional manifold with vanishing streamwise wave number is analyzed with similar tools because it is essential for any shear flow. Finally, the spectral approach is used to disentangle, in an analytical way, the linear and nonlinear terms in the dynamical equations.

  9. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  10. The "vanishing follicle" in women with low number of developing follicles during assisted reproduction.

    Science.gov (United States)

    Younis, Johnny S; Yakovi, Shiran; Izhaki, Ido; Haddad, Sami; Ben-Ami, Moshe

    2018-01-01

    To investigate the occurrence of the "vanishing follicle" phenomenon in women with low number of developing follicles in assisted reproduction. Women with ≤ 6 follicles on the day of hCG administration with ≥ 14mm diameter were prospectively studied. Primary outcome measures were disappearance of ≥14mm and all-diameter follicles on the day of oocyte pick-up compared to the day of hCG administration. Among the 120 women recruited, 95 were found eligible and completed the study. The "vanishing follicle" phenomenon occurred in 3.1% (95% confidence level: 0.7%-9.0%) and 18.9% (95% confidence level: 11.6%-28.3%) of cases affecting ≥14mm and all-diameter follicles, respectively. In all cases, mid-late follicular serum LH and P levels remained within normal follicular phase range and trans-vaginal scan did not show signs of ovulation. Markedly, the main significant difference between the study and control groups in the ≥14mm follicle group was serum E 2 level on the day of hCG administration; median (Interquartile range), corresponding to 395 (382.0-405.5) versus 823.0 (544.5-1291.0) pg/mL, respectively (P=0.04). The same trend was encountered in all-diameter vanishing follicles group but it did not reach significance. Interestingly, in all-diameter vanishing group, chronic smoking and the P/E 2 ratio on the hCG day were significantly higher than controls. Post hoc multiple logistic regression analysis of data in accordance with the Bologna criteria reveled that antral follicle count was found to significantly affect the development of the "vanishing follicle" phenomenon. The "vanishing follicle" phenomenon occasionally occurs in women with low number of developing follicles during assisted reproduction with no signs of ovulation. Our preliminary findings suggest that this phenomenon may be related to exhausted ovarian reserve however, an early-unrecognized LH elevation could not be ruled out. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Design of a projection display screen with vanishing color shift for rear-projection HDTV

    Science.gov (United States)

    Liu, Xiu; Zhu, Jin-lin

    1996-09-01

    Using bi-convex cylinder lens with matrix structure, the transmissive projection display screen with high contrast and wider viewing angle has been widely used in large rear projection TV and video projectors, it obtained a inhere color shift and puzzled the designer of display screen for RGB projection tube in-line adjustment. Based on the method of light beam racing, the general software of designing projection display screen has been developed and the computer model of vanishing color shift for rear projection HDTV has bee completed. This paper discussed the practical designing method to vanish the defect of color shift and mentioned the relations between the primary optical parameters of display screen and relative geometry sizes of lens' surface. The distributions of optical gain to viewing angle and the influences on engineering design are briefly analyzed.

  12. Quad-Rotor Helicopter Autonomous Navigation Based on Vanishing Point Algorithm

    Directory of Open Access Journals (Sweden)

    Jialiang Wang

    2014-01-01

    Full Text Available Quad-rotor helicopter is becoming popular increasingly as they can well implement many flight missions in more challenging environments, with lower risk of damaging itself and its surroundings. They are employed in many applications, from military operations to civilian tasks. Quad-rotor helicopter autonomous navigation based on the vanishing point fast estimation (VPFE algorithm using clustering principle is implemented in this paper. For images collected by the camera of quad-rotor helicopter, the system executes the process of preprocessing of image, deleting noise interference, edge extracting using Canny operator, and extracting straight lines by randomized hough transformation (RHT method. Then system obtains the position of vanishing point and regards it as destination point and finally controls the autonomous navigation of the quad-rotor helicopter by continuous modification according to the calculated navigation error. The experimental results show that the quad-rotor helicopter can implement the destination navigation well in the indoor environment.

  13. Mechanistic Prediction of the Effect of Microstructural Coarsening on Creep Response of SnAgCu Solder Joints

    Science.gov (United States)

    Mukherjee, S.; Chauhan, P.; Osterman, M.; Dasgupta, A.; Pecht, M.

    2016-07-01

    Mechanistic microstructural models have been developed to capture the effect of isothermal aging on time dependent viscoplastic response of Sn3.0Ag0.5Cu (SAC305) solders. SnAgCu (SAC) solders undergo continuous microstructural coarsening during both storage and service because of their high homologous temperature. The microstructures of these low melting point alloys continuously evolve during service. This results in evolution of creep properties of the joint over time, thereby influencing the long term reliability of microelectronic packages. It is well documented that isothermal aging degrades the creep resistance of SAC solder. SAC305 alloy is aged for (24-1000) h at (25-100)°C (~0.6-0.8 × T melt). Cross-sectioning and image processing techniques were used to periodically quantify the effect of isothermal aging on phase coarsening and evolution. The parameters monitored during isothermal aging include size, area fraction, and inter-particle spacing of nanoscale Ag3Sn intermetallic compounds (IMCs) and the volume fraction of micronscale Cu6Sn5 IMCs, as well as the area fraction of pure tin dendrites. Effects of microstructural evolution on secondary creep constitutive response of SAC305 solder joints were then modeled using a mechanistic multiscale creep model. The mechanistic phenomena modeled include: (1) dispersion strengthening by coarsened nanoscale Ag3Sn IMCs in the eutectic phase; and (2) load sharing between pro-eutectic Sn dendrites and the surrounding coarsened eutectic Sn-Ag phase and microscale Cu6Sn5 IMCs. The coarse-grained polycrystalline Sn microstructure in SAC305 solder was not captured in the above model because isothermal aging does not cause any significant change in the initial grain size and orientation of SAC305 solder joints. The above mechanistic model can successfully capture the drop in creep resistance due to the influence of isothermal aging on SAC305 single crystals. Contribution of grain boundary sliding to the creep strain of

  14. Mathematical Modeling of the Growth and Coarsening of Ice Particles in the Context of High Pressure Shift Freezing Processes

    KAUST Repository

    Smith, N. A. S.

    2013-07-25

    High pressure shift freezing (HPSF) has been proven more beneficial for ice crystal size and shape than traditional (at atmospheric pressure) freezing.1-3 A model for growth and coarsening of ice crystals inside a frozen food sample (either at atmospheric or high pressure) is developed, and some numerical experiments are given, with which the model is validated by using experimental data. To the best of our knowledge, this is the first model suited for freezing crystallization in the context of high pressure. © 2013 American Chemical Society.

  15. Mathematical Modeling of the Growth and Coarsening of Ice Particles in the Context of High Pressure Shift Freezing Processes

    KAUST Repository

    Smith, N. A. S.; Burlakov, V. M.; Ramos, Á . M.

    2013-01-01

    High pressure shift freezing (HPSF) has been proven more beneficial for ice crystal size and shape than traditional (at atmospheric pressure) freezing.1-3 A model for growth and coarsening of ice crystals inside a frozen food sample (either at atmospheric or high pressure) is developed, and some numerical experiments are given, with which the model is validated by using experimental data. To the best of our knowledge, this is the first model suited for freezing crystallization in the context of high pressure. © 2013 American Chemical Society.

  16. Vanishing bone disease of the orbital roof: now you see it, now you don't

    International Nuclear Information System (INIS)

    Dharsono, Ferry; Van Heerden, Jolandi; McAuliffe, William; Ardakani, Nima M.; Franconi, Catherine; Honeybul, Stephen; Lind, Christopher R.

    2014-01-01

    We describe a rare case of vascularised orbital roof and calvarial erosions with an associated venous malformation. In the absence of infection, malignancy, trauma and eosinophillic granuloma, the closest previously described entity is vanishing bone disease. Computed tomography (CT), MRI, catheter angiography and pathology were all important in the diagnostic workup to enable surgical planning for biopsy and reconstruction. Ongoing CT and MRI follow-up imaging will determine future treatment planning.

  17. Vanishing viscosity limits of mixed hyperbolic–elliptic systems arising in multilayer channel flows

    International Nuclear Information System (INIS)

    Papaefthymiou, E S; Papageorgiou, D T

    2015-01-01

    This study considers the spatially periodic initial value problem of 2 × 2 quasi-linear parabolic systems in one space dimension having quadratic polynomial flux functions. These systems arise physically in the interfacial dynamics of viscous immiscible multilayer channel flows. The equations describe the spatiotemporal evolution of phase-separating interfaces with dissipation arising from surface tension (fourth-order) and/or stable stratification effects (second-order). A crucial mathematical aspect of these systems is the presence of mixed hyperbolic–elliptic flux functions that provide the only source of instability. The study concentrates on scaled spatially 2π-periodic solutions as the dissipation vanishes, and in particular the behaviour of such limits when generalized dissipation operators (spanning second to fourth-order) are considered. Extensive numerical computations and asymptotic analysis suggest that the existence (or not) of bounded vanishing viscosity solutions depends crucially on the structure of the flux function. In the absence of linear terms (i.e. homogeneous flux functions) the vanishing viscosity limit does not exist in the L ∞ -norm. On the other hand, if linear terms in the flux function are present the computations strongly suggest that the solutions exist and are bounded in the L ∞ -norm as the dissipation vanishes. It is found that the key mechanism that provides such boundedness centres on persistent spatiotemporal hyperbolic–elliptic transitions. Strikingly, as the dissipation decreases, the flux function becomes almost everywhere hyperbolic except on a fractal set of elliptic regions, whose dimension depends on the order of the regularized operator. Furthermore, the spatial structures of the emerging weak solutions are found to support an increasing number of discontinuities (measure-valued solutions) located in the vicinity of the fractally distributed elliptic regions. For the unscaled problem, such spatially

  18. Long Time Evolution of Populations under Selection and Vanishing Mutations

    KAUST Repository

    Raoul, Gaël

    2011-02-08

    In this paper, we consider a long time and vanishing mutations limit of an integro-differential model describing the evolution of a population structured with respect to a continuous phenotypic trait. We show that the asymptotic population is a steady-state of the evolution equation without mutations, and satisfies an evolutionary stability condition. © 2011 Springer Science+Business Media B.V.

  19. Long Time Evolution of Populations under Selection and Vanishing Mutations

    KAUST Repository

    Raoul, Gaë l

    2011-01-01

    In this paper, we consider a long time and vanishing mutations limit of an integro-differential model describing the evolution of a population structured with respect to a continuous phenotypic trait. We show that the asymptotic population is a steady-state of the evolution equation without mutations, and satisfies an evolutionary stability condition. © 2011 Springer Science+Business Media B.V.

  20. On the vanishing electron-mass limit in plasma hydrodynamics in unbounded media

    Czech Academy of Sciences Publication Activity Database

    Donatelli, D.; Feireisl, Eduard; Novotný, A.

    2012-01-01

    Roč. 22, č. 6 (2012), s. 985-1012 ISSN 0938-8974 R&D Projects: GA ČR GA201/09/0917 Institutional research plan: CEZ:AV0Z10190503 Keywords : vanishing electron mass limit * plasma hydrodynamics * compressible fluid Subject RIV: BA - General Mathematics Impact factor: 1.566, year: 2012 http://link.springer.com/article/10.1007%2Fs00332-012-9134-5

  1. Vanishing calcification of the brain in an infant after open heart surgery

    International Nuclear Information System (INIS)

    Begeer, J.H.; Rutgers, A.W.F.; Vencken, L.M.; Hoorntje, T.M.; Meuzelaar, J.J.; Woltersom-Zwierzynska, B.D.

    1991-01-01

    Neurological complications after cardiac operations with the aid of cardiopulmonary bypass and hypothermia are well known. A 6 months-old child is described with severe neurological complications after cardiac surgery for Fallots tetralogy. On the CT scan cortical calcification was seen to vanish. Such calcification has not been reported in similar patients. Possible causes are discussed but the precise pathophysiology of this phenomenon remains unclear. (orig.)

  2. Vanishing calcification of the brain in an infant after open heart surgery

    Energy Technology Data Exchange (ETDEWEB)

    Begeer, J.H.; Rutgers, A.W.F. (Groningen Univ. Hospital (Netherlands). Dept. of Child Neurology); Vencken, L.M. (Groningen Univ. Hospital (Netherlands). Dept. of Neuroradiology); Hoorntje, T.M. (Groningen Univ. Hospital (Netherlands). Dept. of Pediatrics); Meuzelaar, J.J. (Groningen Univ. Hospital (Netherlands). Dept. of Thoracic Surgery); Woltersom-Zwierzynska, B.D. (Groningen Univ. Hospital (Netherlands). Dept. of Anaesthesia)

    1991-08-01

    Neurological complications after cardiac operations with the aid of cardiopulmonary bypass and hypothermia are well known. A 6 months-old child is described with severe neurological complications after cardiac surgery for Fallots tetralogy. On the CT scan cortical calcification was seen to vanish. Such calcification has not been reported in similar patients. Possible causes are discussed but the precise pathophysiology of this phenomenon remains unclear. (orig.).

  3. Weyl geometry and the nonlinear mechanics of distributed point defects

    KAUST Repository

    Yavari, A.

    2012-09-05

    The residual stress field of a nonlinear elastic solid with a spherically symmetric distribution of point defects is obtained explicitly using methods from differential geometry. The material manifold of a solid with distributed point defects-where the body is stress-free-is a flat Weyl manifold, i.e. a manifold with an affine connection that has non-metricity with vanishing traceless part, but both its torsion and curvature tensors vanish. Given a spherically symmetric point defect distribution, we construct its Weyl material manifold using the method of Cartan\\'s moving frames. Having the material manifold, the anelasticity problem is transformed to a nonlinear elasticity problem and reduces the problem of computing the residual stresses to finding an embedding into the Euclidean ambient space. In the case of incompressible neo-Hookean solids, we calculate explicitly this residual stress field. We consider the example of a finite ball and a point defect distribution uniform in a smaller ball and vanishing elsewhere. We show that the residual stress field inside the smaller ball is uniform and hydrostatic. We also prove a nonlinear analogue of Eshelby\\'s celebrated inclusion problem for a spherical inclusion in an isotropic incompressible nonlinear solid. © 2012 The Royal Society.

  4. Nonlinear Science

    CERN Document Server

    Yoshida, Zensho

    2010-01-01

    This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl

  5. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  6. Nonlinear (super)symmetries and amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Kallosh, Renata [Physics Department, Stanford University,382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)

    2017-03-07

    There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E{sub 7(7)} scalar sector symmetries as well as the fermionic goldstino symmetries. We present a universal derivation of the vanishing amplitudes in the single (bosonic or fermionic) soft limit. We explain why, universally, the double-soft limit probes the coset space algebra. We also provide identities describing the multiple-soft limit. We discuss loop corrections to N≥5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.

  7. Border-crossing model for the diffusive coarsening of two-dimensional and quasi-two-dimensional wet foams

    Science.gov (United States)

    Schimming, C. D.; Durian, D. J.

    2017-09-01

    For dry foams, the transport of gas from small high-pressure bubbles to large low-pressure bubbles is dominated by diffusion across the thin soap films separating neighboring bubbles. For wetter foams, the film areas become smaller as the Plateau borders and vertices inflate with liquid. So-called "border-blocking" models can explain some features of wet-foam coarsening based on the presumption that the inflated borders totally block the gas flux; however, this approximation dramatically fails in the wet or unjamming limit where the bubbles become close-packed spheres and coarsening proceeds even though there are no films. Here, we account for the ever-present border-crossing flux by a new length scale defined by the average gradient of gas concentration inside the borders. We compute that it is proportional to the geometric average of film and border thicknesses, and we verify this scaling by numerical solution of the diffusion equation. We similarly consider transport across inflated vertices and surface Plateau borders in quasi-two-dimensional foams. And we show how the d A /d t =K0(n -6 ) von Neumann law is modified by the appearance of terms that depend on bubble size and shape as well as the concentration gradient length scales. Finally, we use the modified von Neumann law to compute the growth rate of the average bubble area, which is not constant.

  8. Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

    Science.gov (United States)

    Xu, Lin-qing; Zhang, Dan-tian; Liu, Yong-chang; Ning, Bao-qun; Qiao, Zhi-xia; Yan, Ze-sheng; Li, Hui-jun

    2014-05-01

    Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facilitates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the formation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener's equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

  9. Effects of Rhenium Addition on the Temporal Evolution of the Nanostructure and Chemistry of a Model Ni-Cr-Al Superalloy. 2; Analysis of the Coarsening Behavior

    Science.gov (United States)

    Yoon, Kevin E.; Noebe, Ronald D.; Seidman, David N.

    2007-01-01

    The temporal evolution of the nanostructure and chemistry of a model Ni-8.5 at.% Cr-10 at.% Al alloy with the addition of 2 at.% Re was studied using transmission electron microscopy and atom-probe tomography in order to measure the number density and mean radius of the y' (LIZ) precipitates and the chemistry of the y'-precipitates and the y (fcc)-matrix. In this article, the coarsening behavior of the y'-precipitates is discussed in detail and compared with the Umantsev-Olson model for multi-component alloys. In addition, the experimental results are evaluated with PrecipiCalc(TradeMark) simulations. The results show that the diffusivities of the solute elements play a major role in the coarsening behavior of the y'-precipitates and that the addition of Re retards the coarsening kinetics and stabilizes the spheroidal morphology of the precipitates by reducing the interfacial energy.

  10. Precipitate Contribution to the Acoustic Nonlinearity in Nickel-Based Superalloy

    Institute of Scientific and Technical Information of China (English)

    Chung-Seok KIM; Cliff J.LISSENDEN

    2009-01-01

    The influence of γ' precipitate on the acoustic nonlinearity is investigated for a nickel-based superalloy,which is subjected to creep deformation.During creep deformation,the cuboidal γ' precipitate is preferentially coarsened in a direction perpendicular to the applied stress axis.The length and shape factor of the γ' precipitate increase with creep time.The increase of relative acoustic nonlinearity with increasing fraction of creep life is discussed in relation to the rafting of γ' precipitate,which is closely related to the scattering and distortion of the acoustic wave.

  11. Nonlinear systems

    CERN Document Server

    Palmero, Faustino; Lemos, M; Sánchez-Rey, Bernardo; Casado-Pascual, Jesús

    2018-01-01

    This book presents an overview of the most recent advances in nonlinear science. It provides a unified view of nonlinear properties in many different systems and highlights many  new developments. While volume 1 concentrates on mathematical theory and computational techniques and challenges, which are essential for the study of nonlinear science, this second volume deals with nonlinear excitations in several fields. These excitations can be localized and transport energy and matter in the form of breathers, solitons, kinks or quodons with very different characteristics, which are discussed in the book. They can also transport electric charge, in which case they are known as polarobreathers or solectrons. Nonlinear excitations can influence function and structure in biology, as for example, protein folding. In crystals and other condensed matter, they can modify transport properties, reaction kinetics and interact with defects. There are also engineering applications in electric lattices, Josephson junction a...

  12. Beyond the Young-Laplace model for cluster growth during dewetting of thin films: effective coarsening exponents and the role of long range dewetting interactions.

    Science.gov (United States)

    Constantinescu, Adi; Golubović, Leonardo; Levandovsky, Artem

    2013-09-01

    Long range dewetting forces acting across thin films, such as the fundamental van der Waals interactions, may drive the formation of large clusters (tall multilayer islands) and pits, observed in thin films of diverse materials such as polymers, liquid crystals, and metals. In this study we further develop the methodology of the nonequilibrium statistical mechanics of thin films coarsening within continuum interface dynamics model incorporating long range dewetting interactions. The theoretical test bench model considered here is a generalization of the classical Mullins model for the dynamics of solid film surfaces. By analytic arguments and simulations of the model, we study the coarsening growth laws of clusters formed in thin films due to the dewetting interactions. The ultimate cluster growth scaling laws at long times are strongly universal: Short and long range dewetting interactions yield the same coarsening exponents. However, long range dewetting interactions, such as the van der Waals forces, introduce a distinct long lasting early time scaling behavior characterized by a slow growth of the cluster height/lateral size aspect ratio (i.e., a time-dependent Young angle) and by effective coarsening exponents that depend on cluster size. In this study, we develop a theory capable of analytically calculating these effective size-dependent coarsening exponents characterizing the cluster growth in the early time regime. Such a pronounced early time scaling behavior has been indeed seen in experiments; however, its physical origin has remained elusive to this date. Our theory attributes these observed phenomena to ubiquitous long range dewetting interactions acting across thin solid and liquid films. Our results are also applicable to cluster growth in initially very thin fluid films, formed by depositing a few monolayers or by a submonolayer deposition. Under this condition, the dominant coarsening mechanism is diffusive intercluster mass transport while the

  13. 'Vanishing' structural effects of temperature in polymer glasses close to the glass-transition temperature

    International Nuclear Information System (INIS)

    Shantarovich, V.P.; Suzuki, T.; Ito, Y.; Yu, R.S.; Kondo, K.; Yampolskii, Yu. P.; Alentiev, A.Yu.

    2007-01-01

    Positron annihilation lifetime (PAL) measurements were used for observation of structural effects of temperature in polystyrene (PS), super-cross-linked polystyrene networks (CPS), and in polyimides (PI) below and in the vicinity of glass-transition temperature T g . 'Vanishing' of these structural effects in the repeating cycles of the temperature controlled PAL experiments due to the slow relaxation processes in different conditions and details of chemical structure is demonstrated. Obtained results illustrate complex, dependent on thermal history, inhomogeneous character of the glass structure. In fact, structure of some polymer glasses is changing continuously. Calculations of the number density of free volume holes in these conditions are discussed

  14. Texture one zero Dirac neutrino mass matrix with vanishing determinant or trace condition

    Science.gov (United States)

    Singh, Madan

    2018-06-01

    In the light of non-zero and relatively large value of rector mixing angle (θ13), we have performed a detailed analysis of texture one zero neutrino mass matrix Mν in the scenario of vanishing determinant/trace conditions, assuming the Dirac nature of neutrinos. In both the scenarios, normal mass ordering is ruled out for all the six possibilities of Mν, however for inverted mass ordering, only two are found to be viable with the current neutrino oscillation data at 3σ confidence level. Numerical and some approximate analytical results are presented.

  15. The parity-preserving massive QED3: Vanishing β-function and no parity anomaly

    Directory of Open Access Journals (Sweden)

    O.M. Del Cima

    2015-11-01

    Full Text Available The parity-preserving massive QED3 exhibits vanishing gauge coupling β-function and is parity and infrared anomaly free at all orders in perturbation theory. Parity is not an anomalous symmetry, even for the parity-preserving massive QED3, in spite of some claims about the possibility of a perturbative parity breakdown, called parity anomaly. The proof is done by using the algebraic renormalization method, which is independent of any regularization scheme, based on general theorems of perturbative quantum field theory.

  16. Vanishing lung syndrome: the importance of the high-resolution CT in its diagnostic

    International Nuclear Information System (INIS)

    Rodriguez Cerezo, M.I.; Porres Azcona, E.; Pina Insausti, L.; Inchusta Sarasibar, M.I.; Mellado Rodriguez, M.

    1995-01-01

    Vanishing lung syndrome, also referred to as idiopathic giant bullions emphysema is a dissolver that has yet to be fully characterized. It is considered a different entry from classic pulmonary emphysema. It is characterized by the presence of large bullae associated with some type of emphysema. High-resolution CT is the best imaging technique to identify the underlying type of emphysema and it helps to determine the viability of the nonbullous lung. We present the case of an asymptomatic patient in whom the diagnosis was suspected on the basis of plain chest X ray and was confirmed by high-resolution CT. 13 refs

  17. On weighted hardy inequalities on semiaxis for functions vanishing at the endpoints

    Directory of Open Access Journals (Sweden)

    Vladimir Stepanov

    1997-01-01

    Full Text Available We study the weighted Hardy inequalities on the semiaxis of the form ‖Fu‖2≤C‖F(kv‖2  (1 for functions vanishing at the endpoints together with derivatives up to the order k−1. The case k=2 is completely characterized.

  18. ''Vanishing theorem'' for a positive holomorphic vector bundle of undefined rank

    International Nuclear Information System (INIS)

    Le Potier, J.

    1974-01-01

    Let M ba a compact complex manifold of dimension n and let E→M be a holomorphic vector bundle over M. Theorem: If E is positive of rank r and if Hsup(p,q)(M,E) is the cohomology of type (p,q) of M with values in E, then Hsup(p,q)(M,E) = O as soon as p+q >=n+r. If r = 1, this is the ''precise vanishing theorem'' due to Kodaira and Nakano; the present paper contains a proof of the general case

  19. Study of nucleation, growth and coarsening of precipitates in a novel 9%Cr heat resistant steel: Experimental and modeling

    International Nuclear Information System (INIS)

    Prat, O.; García, J.; Rojas, D.; Sanhueza, J.P.; Camurri, C.

    2014-01-01

    Nucleation, growth and coarsening of three different precipitates (NbC, M 23 C 6 and V(C,N)) in a novel 9%Cr heat resistant steel designed by the authors were investigated. The microstructure evolution after tempering (780 °C/2 h) and after creep (650 °C/100 MPa) was characterized using transmission electron microscopy in the scanning mode (STEM). Thermodynamic and kinetic modeling was carried out using the softwares Thermo-Calc, DICTRA and TC-PRISMA. The Thermo-Calc software predicted formation of NbC, V(C,N) and M 23 C 6 carbides at the tempering temperature of 780 °C. STEM investigations revealed that M 23 C 6 precipitated on prior austenite grain boundaries and lath or block boundaries whereas NbC and V(C,N) were located within sub-grains. Simulations by TC-PRISMA showed that M 23 C 6 , NbC and V(C,N) particles nucleation begins as soon as the tempering treatment starts and it is completed in a very short time, reaching the equilibrium volume fraction after 40 s for M 23 C 6 , 100 s for NbC and 80 s for V(C,N). Best agreement between simulations and experimental investigations was found for low interfacial energy values of 0.1 J m −2 . Both STEM measurements as well as DICTRA simulations indicate very low coarsening rate for both kind of precipitates. Creep tests up to 4000–5000 h suggest that this special combination of NbC, V(C,N) and M 23 C 6 may provide increased pinning of dislocations reducing boundary migration therefore enhancing creep strength. - Highlights: • Nucleation, growth and coarsening of NbC and M 23 C 6 precipitates were investigated. • The microstructure was characterized using transmission electron microscopy (STEM). • Modeling was carried out using the softwares Thermo-Calc, DICTRA and TC-PRISMA. • M 23 C 6 and NbC nucleation begins as soon as the solution treatmentinitiates. • Best agreement modeling/experiments was found for low interfacial energy values of 0.1 J m −2

  20. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  1. Modelling of pore coarsening in the high burn-up structure of UO{sub 2} fuel

    Energy Technology Data Exchange (ETDEWEB)

    Veshchunov, M.S.; Tarasov, V.I., E-mail: tarasov@ibrae.ac.ru

    2017-05-15

    The model for coalescence of randomly distributed immobile pores owing to their growth and impingement, applied by the authors earlier to consideration of the porosity evolution in the high burn-up structure (HBS) at the UO{sub 2} fuel pellet periphery (rim zone), was further developed and validated. Predictions of the original model, taking into consideration only binary impingements of growing immobile pores, qualitatively correctly describe the decrease of the pore number density with the increase of the fractional porosity, however notably underestimate the coalescence rate at high burn-ups attained in the outmost region of the rim zone. In order to overcome this discrepancy, the next approximation of the model taking into consideration triple impingements of growing pores was developed. The advanced model provides a reasonable consent with experimental data, thus demonstrating the validity of the proposed pore coarsening mechanism in the HBS.

  2. Comparative study of He bubble formation in nanostructured reduced activation steel and its coarsen-grained counterpart

    Science.gov (United States)

    Liu, W. B.; Zhang, J. H.; Ji, Y. Z.; Xia, L. D.; Liu, H. P.; Yun, D.; He, C. H.; Zhang, C.; Yang, Z. G.

    2018-03-01

    High temperature (550 °C) He ions irradiation was performed on nanostructured (NS) and coarsen-grained (CG) reduced activation steel to investigate the effects of GBs/interfaces on the formation of bubbles during irradiation. Experimental results showed that He bubbles were preferentially trapped at dislocations and/or grain boundaries (GBs) for both of the samples. Void denuded zones (VDZs) were observed in the CG samples, while VDZs near GBs were unobvious in NS sample. However, both the average bubble size and the bubble density in peak damage region of the CG sample were significantly larger than that observed in the NS sample, which indicated that GBs play an important role during the irradiation, and the NS steel had better irradiation resistance than its CG counterpart.

  3. Nonlinear systems

    National Research Council Canada - National Science Library

    Drazin, P. G

    1992-01-01

    This book is an introduction to the theories of bifurcation and chaos. It treats the solution of nonlinear equations, especially difference and ordinary differential equations, as a parameter varies...

  4. Nonlinear analysis

    CERN Document Server

    Gasinski, Leszek

    2005-01-01

    Hausdorff Measures and Capacity. Lebesgue-Bochner and Sobolev Spaces. Nonlinear Operators and Young Measures. Smooth and Nonsmooth Analysis and Variational Principles. Critical Point Theory. Eigenvalue Problems and Maximum Principles. Fixed Point Theory.

  5. Vanishing Lung Syndrome in a Patient with HIV Infection and Heavy Marijuana Use

    Directory of Open Access Journals (Sweden)

    Basheer Tashtoush

    2014-01-01

    Full Text Available Vanishing lung syndrome (VLS is a rare and distinct clinical syndrome that usually affects young men. VLS leads to severe progressive dyspnea and is characterized by extensive, asymmetric, peripheral, and predominantly upper lobe giant lung bullae. Case reports have suggested an additive role of marijuana use in the development of this disease in young male tobacco smokers. We herein report a case of a 65-year-old Hispanic male previously diagnosed with severe emphysema and acquired immune deficiency syndrome (AIDS, with a history of intravenous heroin use and active marijuana smoking who presents to the emergency department with severe progressive shortness of breath he was found to have multiple large subpleural bullae occupying more than one-third of the hemithorax on chest computerized tomography (CT, characteristic of vanishing lung syndrome. The patient was mechanically ventilated and later developed a pneumothorax requiring chest tube placement and referral for surgical bullectomy. Surgical bullectomy has shown high success rates in alleviating the debilitating symptoms and preventing the life threatening complications of this rare syndrome. This case further emphasizes the importance of recognizing VLS in patients with severe emphysema and heavy marijuana smoking.

  6. BULK THERMODYNAMICS AND CHARGE FLUCTUATIONS AT NON-VANISHING BARYON DENSITY

    International Nuclear Information System (INIS)

    MIAO, C.; SCHMIDT, C.

    2007-01-01

    We present results on bulk thermodynamic quantities as well as net baryon number, strangeness and electric charge fluctuations in QCD at non-zero density and temperature obtained from lattice calculations with almost physical quark masses for two values of the lattice cut-off aT = 1/4 and 1/6. We show that with our improved p4fa3-action the cut-off effects are under control when using lattices with a temporal extent of 6 or larger and that the contribution to the equation of state, which is due to a finite chemical potential is small for μ q /T < 1. Moreover, at vanishing chemical potential, i.e. under conditions almost realized at RHIC and the LHC, quartic fluctuations of net baryon number and strangeness are large in a narrow temperature interval characterizing the transition region from the low to high temperature phase. At non-zero baryon number density, strangeness fluctuations are enhanced and correlated to fluctuations of the net baryon number. If strangeness is furthermore forced to vanish, as it may be the case in systems created in heavy ion collisions, strangeness fluctuations are significantly smaller than baryon number fluctuations

  7. Convergence of spectral methods for nonlinear conservation laws. Final report

    International Nuclear Information System (INIS)

    Tadmor, E.

    1987-08-01

    The convergence of the Fourier method for scalar nonlinear conservation laws which exhibit spontaneous shock discontinuities is discussed. Numerical tests indicate that the convergence may (and in fact in some cases must) fail, with or without post-processing of the numerical solution. Instead, a new kind of spectrally accurate vanishing viscosity is introduced to augment the Fourier approximation of such nonlinear conservation laws. Using compensated compactness arguments, it is shown that this spectral viscosity prevents oscillations, and convergence to the unique entropy solution follows

  8. Note on off-shell relations in nonlinear sigma model

    International Nuclear Information System (INIS)

    Chen, Gang; Du, Yi-Jian; Li, Shuyi; Liu, Hanqing

    2015-01-01

    In this note, we investigate relations between tree-level off-shell currents in nonlinear sigma model. Under Cayley parametrization, all odd-point currents vanish. We propose and prove a generalized U(1) identity for even-point currents. The off-shell U(1) identity given in http://dx.doi.org/10.1007/JHEP01(2014)061 is a special case of the generalized identity studied in this note. The on-shell limit of this identity is equivalent with the on-shell KK relation. Thus this relation provides the full off-shell correspondence of tree-level KK relation in nonlinear sigma model.

  9. Properties of some nonlinear Schroedinger equations motivated through information theory

    International Nuclear Information System (INIS)

    Yuan, Liew Ding; Parwani, Rajesh R

    2009-01-01

    We update our understanding of nonlinear Schroedinger equations motivated through information theory. In particular we show that a q-deformation of the basic nonlinear equation leads to a perturbative increase in the energy of a system, thus favouring the simplest q = 1 case. Furthermore the energy minimisation criterion is shown to be equivalent, at leading order, to an uncertainty maximisation argument. The special value η = 1/4 for the interpolation parameter, where leading order energy shifts vanish, implies the preservation of existing supersymmetry in nonlinearised supersymmetric quantum mechanics. Physically, η might be encoding relativistic effects.

  10. Simplified Model of Nonlinear Landau Damping

    International Nuclear Information System (INIS)

    Yampolsky, N.A.; Fisch, N.J.

    2009-01-01

    The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.

  11. Nonlinear optimization

    CERN Document Server

    Ruszczynski, Andrzej

    2011-01-01

    Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates the theory and the methods of nonlinear optimization in a unified, clear, and mathematically rigorous fashion, with detailed and easy-to-follow proofs illustrated by numerous examples and figures. The book covers convex analysis, the theory of optimality conditions, duality theory, and numerical methods for solving unconstrained and constrained optimization problems. It addresses not only classical material but also modern top...

  12. More on non-supersymmetric asymmetric orbifolds with vanishing cosmological constant

    International Nuclear Information System (INIS)

    Sugawara, Yuji; Wada, Taiki

    2016-01-01

    We explore various non-supersymmetric type II string vacua constructed based on asymmetric orbifolds of tori with vanishing cosmological constant at the one loop. The string vacua we present are modifications of the models studied in http://dx.doi.org/10.1007/JHEP02(2016)184, of which orbifold group is just generated by a single element. We especially focus on two types of modifications: (i) the orbifold twists include different types of chiral reflections not necessarily removing massless Rarita-Schwinger fields in the 4-dimensional space-time, (ii) the orbifold twists do not include the shift operator. We further discuss the unitarity and stability of constructed non-supersymmetric string vacua, with emphasizing the common features of them.

  13. Multiloop amplitudes and vanishing theorems using the pure spinor formalism for the superstring

    International Nuclear Information System (INIS)

    Berkovits, Nathan

    2004-01-01

    A ten-dimensional super-Poincare covariant formalism for the superstring was recently developed which involves a BRST operator constructed from superspace matter variables and a pure spinor ghost variable. A super-Poincare covariant prescription was defined for computing tree amplitudes and was shown to coincide with the standard RNS prescription. In this paper, picture-changing operators are used to define functional integration over the pure spinor ghosts and to construct a suitable b ghost. A super-Poincare covariant prescription is then given for the computation of N-point multiloop amplitudes. One can easily prove that massless N-point multiloop amplitudes vanish for N 4 terms in the effective action receive no perturbative contributions above one loop. (author)

  14. Brane solutions sourced by a scalar with vanishing potential and classification of scalar branes

    Energy Technology Data Exchange (ETDEWEB)

    Cadoni, Mariano [Dipartimento di Fisica, Università di Cagliari,Cittadella Universitaria, 09042 Monserrato (Italy); INFN, Sezione di Cagliari,Cagliari (Italy); Franzin, Edgardo [Dipartimento di Fisica, Università di Cagliari,Cittadella Universitaria, 09042 Monserrato (Italy); INFN, Sezione di Cagliari,Cagliari (Italy); CENTRA, Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa,Avenida Rovisco Pais 1, 1049 Lisboa (Portugal); Serra, Matteo [Dipartimento di Matematica, Sapienza Università di Roma,Piazzale Aldo Moro 2, 00185 Roma (Italy)

    2016-01-20

    We derive exact brane solutions of minimally coupled Einstein-Maxwell-scalar gravity in d+2 dimensions with a vanishing scalar potential and we show that these solutions are conformal to the Lifshitz spacetime whose dual QFT is characterized by hyperscaling violation. These solutions, together with the AdS brane and the domain wall sourced by an exponential potential, give the complete list of scalar branes sourced by a generic potential having simple (scale-covariant) scaling symmetries not involving Galilean boosts. This allows us to give a classification of both simple and interpolating brane solution of minimally coupled Einstein-Maxwell-scalar gravity having no Schrödinger isometries, which may be very useful for holographic applications.

  15. Vanishing corrections on intermediate scale and implications for unification of forces

    International Nuclear Information System (INIS)

    Parida, M.K.

    1996-02-01

    In two-step breakings of a class of grand unified theories including SO(10), we prove a theorem showing that the scale (M I ) where the Pati-Salam gauge symmetry with parity breaks down to the standard gauge group, has vanishing corrections due to all sources emerging from higher scales (μ > M I ) such as the one-loop and all higher-loop effects, the GUT-threshold, gravitational smearing, and string threshold effects. Implications of such a scale for the unification of gauge couplings with small Majorana neutrino masses are discussed. In string inspired SO(10), we show that M I ≅ 5 x 10 12 GeV, needed for neutrino masses, with the GUT scale M U ≅ M str can be realized provided certain particle states in the predicted spectrum are light. (author). 28 refs, 1 tab

  16. The unified approach to integrable relativistic equations: Soliton solutions over non-vanishing backgrounds - 1

    International Nuclear Information System (INIS)

    Barashenkov, I.V.; Getmanov, B.S.; Kovtun, V.E.

    1992-01-01

    The scheme for unified description of integrable relativistic massive systems provides an inverse scattering formalism that covers universally all (1+1)- dimensional systems of this kind. In this work we construct the N-soliton solution (over an arbitrary background) for some generic system which is associated with the sl(2,C) case of the scheme and whose reductions include the complex sine-Gordon equation, the massive Thirring model and other equations, both in the Euclidean and Minkowski spaces. Thus the N-soliton solutions for all these systems emerge in a unified form differing only in the type of constraints imposed on their parameters. In an earlier paper the case of the zero background was considered while here we concentrate on the case of the non-vanishing constant background i.e., on the N-kink solutions. (author). 18 refs

  17. Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

    KAUST Repository

    Yavari, Arash

    2012-03-09

    We present a geometric theory of nonlinear solids with distributed dislocations. In this theory the material manifold-where the body is stress free-is a Weitzenböck manifold, that is, a manifold with a flat affine connection with torsion but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan\\'s moving frames we construct the material manifold for several examples of bodies with distributed dislocations. We also present non-trivial examples of zero-stress dislocation distributions. More importantly, in this geometric framework we are able to calculate the residual stress fields, assuming that the nonlinear elastic body is incompressible. We derive the governing equations of nonlinear dislocation mechanics covariantly using balance of energy and its covariance. © 2012 Springer-Verlag.

  18. Factors which influence directional coarsening of Gamma prime during creep in nickel-base superalloy single crystals

    International Nuclear Information System (INIS)

    Mackay, R.A.; Ebert, L.J.

    1984-01-01

    Changes in the morphology of the gamma prime precipitate were examined as a function of time during creep at 982 C in 001 oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80 pct., the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The effects of initial microstructure and alloy composition of raft development and creep properties were investigated. Directional coarsening of gamma prime begins during primary creep and continues well after the onset of second state creep. The thickness of the rafts remains constant up through the onset of tertiary creep a clear indication of the stability of the finely-spaced gamma/gamma prime lamellar structure. The thickness of the rafts which formed was equal to the initial gamma prime size which was present prior to testing. The single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma/gamma prime interfaces per unit volume of material. Reducing the Mo content by only 0.73 wt. pct. increased the creep life by a factor of three, because the precipitation of a third phase was eliminated

  19. Coarsening in 3D nonconserved Ising model at zero temperature: Anomaly in structure and slow relaxation of order-parameter autocorrelation

    Science.gov (United States)

    Chakraborty, Saikat; Das, Subir K.

    2017-09-01

    Via Monte Carlo simulations we study pattern and aging during coarsening in a nonconserved nearest-neighbor Ising model, following quenches from infinite to zero temperature, in space dimension d = 3. The decay of the order-parameter autocorrelation function appears to obey a power-law behavior, as a function of the ratio between the observation and waiting times, in the large ratio limit. However, the exponent of the power law, estimated accurately via a state-of-the-art method, violates a well-known lower bound. This surprising fact has been discussed in connection with a quantitative picture of the structural anomaly that the 3D Ising model exhibits during coarsening at zero temperature. These results are compared with those for quenches to a temperature above that of the roughening transition.

  20. The Vanished Child: An inquiry into figures and their modes of appearance

    Directory of Open Access Journals (Sweden)

    Bertrand Gervais

    2010-12-01

    Full Text Available Sophie Calle's texts are elaborate devices that facilitate the production of figures, of complex symbolic entities. In fact, her work enables us to better understand how figures emerge and unfold in the imaginary. Thus, we find in her Disparitions (Disappearances, a startling figure, which we can name the "Vanished Child". I will present this figure and explain how it stems from the description of a painting by Rembrandt, stolen at the Gardner Museum in Boston. I will start by identifying some of the essential processes implied in the identification of a figure, and, to do so, I will give two short examples, drawn from Witold Gombrowicz and Don DeLillo. Then, after having described in details the figure of the Vanished Child, I will argue, following the French art historian Georges Didi-Huberman in his reading of Walter Benjamin, that figures are auratic objects. Dans ses textes, Sophie Calle emploie des techniques détaillées qui facilitent la production de figures, d'entités symboliques complexes. Son œuvre nous permet effectivement de mieux comprendre comment les figures émergent et se déploient dans l'imaginaire. Ainsi, nous trouvons dans ses Disparitions (Disappearances une figure surprenante que nous pouvons désigner comme « l'enfant disparu ». Je présenterai cette figure en expliquant comment elle découle de la description d'un tableau de Rembrandt volé au musée Gardner à Boston. J'identifierai d'abord quelques-uns des procédés essentiels à l'identification d'une figure, et pour ce faire je donnerai deux exemples, tirés des œuvres de Witold Gombrowicz et Don DeLillo. Puis je décrirai de façon détaillée la figure de l'enfant disparu, avant de démontrer le caractère auratique des figures à partir de la lecture de Walter Benjamin qu'exécute l'historien de l'art français Georges Didi-Huberman.

  1. Dressing method and quadratic bundles related to symmetric spaces. Vanishing boundary conditions

    Science.gov (United States)

    Valchev, T. I.

    2016-02-01

    We consider quadratic bundles related to Hermitian symmetric spaces of the type SU(m + n)/S(U(m) × U(n)). The simplest representative of the corresponding integrable hierarchy is given by a multi-component Kaup-Newell derivative nonlinear Schrödinger equation which serves as a motivational example for our general considerations. We extensively discuss how one can apply Zakharov-Shabat's dressing procedure to derive reflectionless potentials obeying zero boundary conditions. Those could be used for one to construct fast decaying solutions to any nonlinear equation belonging to the same hierarchy. One can distinguish between generic soliton type solutions and rational solutions.

  2. Vanishing of the vacuum amplitude of heterotic string compactified on a tensor product of N=2 superconformal models

    International Nuclear Information System (INIS)

    Kei Ito.

    1988-07-01

    The vacuum amplitude of heterotic string compactified on a tensor product of nine copies of c=1, N=2 superconformal models is shown to vanish due to a generalized Riemann's theta identity associated with the 12x12 matrix identity t BB=6 2 I 12 , identity B ij =-5(i=j), 1(i≠j). (author). 4 refs

  3. No evidence that polymorphisms of the vanishing white matter disease genes are risk factors in multiple sclerosis

    NARCIS (Netherlands)

    Pronk, J.C.; Scheper, G.C.; Andel, R.J.; van Berkel, C.G.M.; Polman, C.H.; Uitdehaag, B.M.J.; van der Knaap, M.S.

    2008-01-01

    Febrile infections are known to cause exacerbations in the white matter disorders 'vanishing white matter' (VWM) and multiple sclerosis (MS). We hypothesized that polymorphisms in EIF2B1-5, the genes involved in VWM, might be risk factors for the development of MS or temperature sensitivity in

  4. Nonlinear optical properties of an electromagnetically induced transparency medium interacting with two quantized fields

    CERN Document Server

    Kuang-Leman; Wu Yong Shi

    2003-01-01

    We study linear and nonlinear optical properties of an electromagnetically induced transparency (EIT) medium interacting with two quantized laser fields in the adiabatic EIT case. We show that the EIT medium exhibits normal dispersion. Kerr and higher-order nonlinear refractive index coefficients are also calculated in a completely analytical form. It is indicated that the EIT medium exhibits giant resonantly enhanced nonlinearities. We discuss the response of the EIT medium to nonclassical light fields and find that the polarization vanishes when the probe laser is initially in a nonclassical state of no single-photon coherence.

  5. Continuous dependence estimates for viscosity solutions of fully nonlinear degenerate elliptic equations

    Directory of Open Access Journals (Sweden)

    Espen R. Jakobsen

    2002-05-01

    Full Text Available Using the maximum principle for semicontinuous functions [3,4], we prove a general ``continuous dependence on the nonlinearities'' estimate for bounded Holder continuous viscosity solutions of fully nonlinear degenerate elliptic equations. Furthermore, we provide existence, uniqueness, and Holder continuity results for bounded viscosity solutions of such equations. Our results are general enough to encompass Hamilton-Jacobi-Bellman-Isaacs's equations of zero-sum, two-player stochastic differential games. An immediate consequence of the results obtained herein is a rate of convergence for the vanishing viscosity method for fully nonlinear degenerate elliptic equations.

  6. Heterogeneous coarsening of Pb phase and the effect of Cu addition on it in a nanophase composite of Al-10 wt%Pb alloy prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Zhu, M.; Liu, X.; Wu, Z.F.; Ouyang, L.Z.; Zeng, M.Q.

    2009-01-01

    A nanophase composite of Al-10 wt%Pb alloy was prepared by mechanical alloying. The coarsening behavior of Pb phase in the composite during heating process was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nanoindentation test. The present work shows that the Pb phase grew substantially and had two different size distributions when the heating temperature was above 823 K. The different size distributions of Pb phase were owing to different grain size ranges of Al matrix in different regions, which led to the different growth rates of the Pb phase in those regions. It has been proposed that the different size ranges of Al grain appeared upon heating were originated from a statistical size distribution of Al grains in the as-milled powder. With the addition of a small amount of Cu, the heterogeneous growth of Pb phase can be suppressed, and the coarsening of Pb phase shows two distinct rates. This indicates that the coarsening is mainly governed by grain boundary diffusion and lattice diffusion of Al matrix in the initial stage and the later one, respectively

  7. Vanishing Viscosity Approach to the Compressible Euler Equations for Transonic Nozzle and Spherically Symmetric Flows

    Science.gov (United States)

    Chen, Gui-Qiang G.; Schrecker, Matthew R. I.

    2018-04-01

    We are concerned with globally defined entropy solutions to the Euler equations for compressible fluid flows in transonic nozzles with general cross-sectional areas. Such nozzles include the de Laval nozzles and other more general nozzles whose cross-sectional area functions are allowed at the nozzle ends to be either zero (closed ends) or infinity (unbounded ends). To achieve this, in this paper, we develop a vanishing viscosity method to construct globally defined approximate solutions and then establish essential uniform estimates in weighted L p norms for the whole range of physical adiabatic exponents γ\\in (1, ∞) , so that the viscosity approximate solutions satisfy the general L p compensated compactness framework. The viscosity method is designed to incorporate artificial viscosity terms with the natural Dirichlet boundary conditions to ensure the uniform estimates. Then such estimates lead to both the convergence of the approximate solutions and the existence theory of globally defined finite-energy entropy solutions to the Euler equations for transonic flows that may have different end-states in the class of nozzles with general cross-sectional areas for all γ\\in (1, ∞) . The approach and techniques developed here apply to other problems with similar difficulties. In particular, we successfully apply them to construct globally defined spherically symmetric entropy solutions to the Euler equations for all γ\\in (1, ∞).

  8. Acute vanishing bile duct syndrome after therapy with cephalosporin, metronidazole, and clotrimazole: A case report.

    Science.gov (United States)

    Zhao, Zonghao; Bao, Lei; Yu, Xiaolan; Zhu, Chuanlong; Xu, Jing; Wang, Yu; Yin, Ming; Li, Yi; Li, Wenting

    2017-09-01

    Vanishing bile duct syndrome (VBDS) consists of a series of diseases characterized by the loss of >50% bile duct in portal areas. Many factors are associated with VBDS including infections, neoplasms, and drugs. Antibiotic is one of the most frequently reported causes of VBDS. A 29-year-old female was admitted because of liver injury for over 3 months. Tests for viruses that can cause hepatitis and autoantibodies were all negative. She was prescribed with antibiotics approximately a week before liver injury while there was no history of alcohol consumption. Liver biopsy demonstrated a loss of intrahepatic bile duct in most of the portal tracts. This patient was treated with ursodeoxycholic acid, polyene phosphatidylcholine, and bicyclol. Most importantly, the treatments in our hospital were proved by the ethics committee of Department of Infectious Disease, Anhui Provincial Hospital. The symptoms were improved. She is still under treatment. VBDS is rare but can be severe. A liver biopsy offers an important evidence for the diagnosis of VBDS, especially for those with a history of susceptible drugs taking.

  9. Grafting and Poisson Structure in (2+1)-Gravity with Vanishing Cosmological Constant

    Science.gov (United States)

    Meusburger, C.

    2006-09-01

    We relate the geometrical construction of (2+1)-spacetimes via grafting to phase space and Poisson structure in the Chern-Simons formulation of (2+1)-dimensional gravity with vanishing cosmological constant on manifolds of topology mathbb{R} × S_g, where S g is an orientable two-surface of genus g>1. We show how grafting along simple closed geodesics λ is implemented in the Chern-Simons formalism and derive explicit expressions for its action on the holonomies of general closed curves on S g .We prove that this action is generated via the Poisson bracket by a gauge invariant observable associated to the holonomy of λ. We deduce a symmetry relation between the Poisson brackets of observables associated to the Lorentz and translational components of the holonomies of general closed curves on S g and discuss its physical interpretation. Finally, we relate the action of grafting on the phase space to the action of Dehn twists and show that grafting can be viewed as a Dehn twist with a formal parameter θ satisfying θ2 = 0.

  10. Isospin effects on the system mass dependence of nuclear stopping around the energy of vanishing flow

    Science.gov (United States)

    Jain, Anupriya; Kumar, Suneel

    2014-10-01

    We study the effect of isospin degree of freedom on nuclear stopping throughout the mass range 50 and 350 for two sets of isotopic systems with N/Z ≈ 1.5 and 1.8, as well as isobaric systems with N/Z = 1.0 and 1.4. Analysis is carried out at incident energies below, at, and above the energy of vanishing flow (EVF) using the isospin-dependent quantum molecular dynamics model. Our findings reveal that nuclear stopping does not show any particular behavior at the EVF. Moreover, system size effects dominate the isospin effects throughout the range of colliding geometry. The Coulomb effects, however, become important at peripheral geometry. The comparative study of the counterbalancing of Coulomb and mean field by removing the nucleon-nucleon collisions and symmetry potential clearly indicates the dominance of nucleon-nucleon cross-section over the Coulomb repulsions. Moreover, the theoretical results presented in this manuscript for the set of reactions can be experimentally verified.

  11. Similarities and differences between infantile and early childhood onset vanishing white matter disease.

    Science.gov (United States)

    Zhou, Ling; Zhang, Haihua; Chen, Na; Zhang, Zhongbin; Liu, Ming; Dai, Lifang; Wang, Jingmin; Jiang, Yuwu; Wu, Ye

    2018-06-01

    Vanishing white matter disease (VWM) is one of the most prevalent inherited leukoencephalopathies in childhood. Infantile VWM is more severe but less understood than the classic early childhood type. We performed a follow-up study on 14 infantile and 26 childhood patients to delineate the natural history and neuroimaging features of VWM. Infantile and childhood patients shared similarities in the incidence of epileptic seizure (35.7 vs. 38.5%) and episodic aggravation (92.9 vs. 84.6%). Developmental delay before disease onset was more common in infantile patients. Motor disability was earlier and more severe in infantile VWM. In survivors with disease durations of 1-3 years, the Gross Motor Function Classification System (GMFCS) was classified as IV-V in 66.7% of infantile and only 29.4% of childhood patients. Kaplan-Meier survival curve analysis indicated that the 5-year survival rates were 21.6 and 91.3% in infantile and childhood VWM, respectively. In terms of MRI, infantile patients showed more extensive involvement and earlier rarefaction, with more common involvement of subcortical white matter, internal capsule, brain stem and dentate nuclei of the cerebellum. Restricted diffusion was more diffuse or extensive in infantile patients. In addition, four novel mutations were identified. In conclusion, we identified some similarities and differences in the natural history and neuroimaging features between infantile and early childhood VWM.

  12. String theory in polar coordinates and the vanishing of the one-loop Rindler entropy

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, Thomas G. [Joseph Henry Laboratories, Princeton University,Princeton, NJ 08544 (United States); Verschelde, Henri [Ghent University, Department of Physics and Astronomy,Krijgslaan, 281-S9, 9000 Gent (Belgium); Zakharov, Valentin I. [ITEP, B. Cheremushkinskaya 25, Moscow, 117218 (Russian Federation); Moscow Inst Phys & Technol,Dolgoprudny, Moscow Region, 141700 (Russian Federation); School of Biomedicine, Far Eastern Federal University,Sukhanova str 8, Vladivostok 690950 (Russian Federation)

    2016-08-19

    We analyze the string spectrum of flat space in polar coordinates, following the small curvature limit of the SL(2,ℝ)/U(1) cigar CFT. We first analyze the partition function of the cigar itself, making some clarifications of the structure of the spectrum that have escaped attention up to this point. The superstring spectrum (type 0 and type II) is shown to exhibit an involution symmetry, that survives the small curvature limit. We classify all marginal states in polar coordinates for type II superstrings, with emphasis on their links and their superconformal structure. This classification is confirmed by an explicit large τ{sub 2} analysis of the partition function. Next we compare three approaches towards the type II genus one entropy in Rindler space: using a sum-over-fields strategy, using a Melvin model approach as in http://dx.doi.org/10.1007/JHEP05(2015)106 and finally using a saddle point method on the cigar partition function. In each case we highlight possible obstructions and motivate that the correct procedures yield a vanishing result: S=0. We finally discuss how the QFT UV divergences of the fields in the spectrum disappear when computing the free energy and entropy using Euclidean techniques.

  13. Isospin effects on the system mass dependence of nuclear stopping around the energy of vanishing flow

    International Nuclear Information System (INIS)

    Jain, Anupriya; Kumar, Suneel

    2014-01-01

    We study the effect of isospin degree of freedom on nuclear stopping throughout the mass range 50 and 350 for two sets of isotopic systems with N/Z ≈ 1.5 and 1.8, as well as isobaric systems with N/Z = 1.0 and 1.4. Analysis is carried out at incident energies below, at, and above the energy of vanishing flow (EVF) using the isospin-dependent quantum molecular dynamics model. Our findings reveal that nuclear stopping does not show any particular behavior at the EVF. Moreover, system size effects dominate the isospin effects throughout the range of colliding geometry. The Coulomb effects, however, become important at peripheral geometry. The comparative study of the counterbalancing of Coulomb and mean field by removing the nucleon–nucleon collisions and symmetry potential clearly indicates the dominance of nucleon–nucleon cross-section over the Coulomb repulsions. Moreover, the theoretical results presented in this manuscript for the set of reactions can be experimentally verified. (paper)

  14. Vanishing of local non-Gaussianity in canonical single field inflation

    Science.gov (United States)

    Bravo, Rafael; Mooij, Sander; Palma, Gonzalo A.; Pradenas, Bastián

    2018-05-01

    We study the production of observable primordial local non-Gaussianity in two opposite regimes of canonical single field inflation: attractor (standard single field slow-roll inflation) and non attractor (ultra slow-roll inflation). In the attractor regime, the standard derivation of the bispectrum's squeezed limit using co-moving coordinates gives the well known Maldacena's consistency relation fNL = 5 (1‑ns) / 12. On the other hand, in the non-attractor regime, the squeezed limit offers a substantial violation of this relation given by fNL = 5/2. In this work we argue that, independently of whether inflation is attractor or non-attractor, the size of the observable primordial local non-Gaussianity is predicted to be fNLobs = 0 (a result that was already understood to hold in the case of attractor models). To show this, we follow the use of the so-called Conformal Fermi Coordinates (CFC), recently introduced in the literature. These coordinates parametrize the local environment of inertial observers in a perturbed FRW spacetime, allowing one to identify and compute gauge invariant quantities, such as n-point correlation functions. Concretely, we find that during inflation, after all the modes have exited the horizon, the squeezed limit of the 3-point correlation function of curvature perturbations vanishes in the CFC frame, regardless of the inflationary regime. We argue that such a cancellation should persist after inflation ends.

  15. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all R R . Assuming the existence of an upper and of a lower ...

  16. Causal Effect of Self-esteem on Cigarette Smoking Stages in Adolescents: Coarsened Exact Matching in a Longitudinal Study.

    Science.gov (United States)

    Khosravi, Ahmad; Mohammadpoorasl, Asghar; Holakouie-Naieni, Kourosh; Mahmoodi, Mahmood; Pouyan, Ali Akbar; Mansournia, Mohammad Ali

    2016-12-01

    Identification of the causal impact of self-esteem on smoking stages faces seemingly insurmountable problems in observational data, where self-esteem is not manipulable by the researcher and cannot be assigned randomly. The aim of this study was to find out if weaker self-esteem in adolescence is a risk factor of cigarette smoking in a longitudinal study in Iran. In this longitudinal study, 4,853 students (14-18 years) completed a self-administered multiple-choice anonym questionnaire. The students were evaluated twice, 12 months apart. Students were matched based on coarsened exact matching on pretreatment variables, including age, gender, smoking stages at the first wave of study, socioeconomic status, general risk-taking behavior, having a smoker in the family, having a smoker friend, attitude toward smoking, and self-injury, to ensure statistically equivalent comparison groups. Self-esteem was measured using the Rosenberg 10-item questionnaire and were classified using a latent class analysis. After matching, the effect of self-esteem was evaluated using a multinomial logistic model. In the causal fitted model, for adolescents with weaker self-esteem relative to those with stronger self-esteem, the relative risk for experimenters and regular smokers relative to nonsmokers would be expected to increase by a factor of 2.2 (1.9-2.6) and 2.0 (1.5-2.6), respectively. Using a causal approach, our study indicates that low self-esteem is consistently associated with progression in cigarette smoking stages.

  17. Turbulence closure: turbulence, waves and the wave-turbulence transition – Part 1: Vanishing mean shear

    Directory of Open Access Journals (Sweden)

    H. Z. Baumert

    2009-03-01

    Full Text Available This paper extends a turbulence closure-like model for stably stratified flows into a new dynamic domain in which turbulence is generated by internal gravity waves rather than mean shear. The model turbulent kinetic energy (TKE, K balance, its first equation, incorporates a term for the energy transfer from internal waves to turbulence. This energy source is in addition to the traditional shear production. The second variable of the new two-equation model is the turbulent enstrophy (Ω. Compared to the traditional shear-only case, the Ω-equation is modified to account for the effect of the waves on the turbulence time and space scales. This modification is based on the assumption of a non-zero constant flux Richardson number in the limit of vanishing mean shear when turbulence is produced exclusively by internal waves. This paper is part 1 of a continuing theoretical development. It accounts for mean shear- and internal wave-driven mixing only in the two limits of mean shear and no waves and waves but no mean shear, respectively.

    The new model reproduces the wave-turbulence transition analyzed by D'Asaro and Lien (2000b. At small energy density E of the internal wave field, the turbulent dissipation rate (ε scales like ε~E2. This is what is observed in the deep sea. With increasing E, after the wave-turbulence transition has been passed, the scaling changes to ε~E1. This is observed, for example, in the highly energetic tidal flow near a sill in Knight Inlet. The new model further exhibits a turbulent length scale proportional to the Ozmidov scale, as observed in the ocean, and predicts the ratio between the turbulent Thorpe and Ozmidov length scales well within the range observed in the ocean.

  18. A vanishing diffusion limit in a nonstandard system of phase field equations

    Czech Academy of Sciences Publication Activity Database

    Colli, P.; Gilardi, G.; Krejčí, Pavel; Sprekels, J.

    2014-01-01

    Roč. 3, č. 2 (2014), s. 257-275 ISSN 2163-2480 R&D Projects: GA ČR GAP201/10/2315 Institutional support: RVO:67985840 Keywords : nonstandard phase field system * nonlinear partial differential equations * asympotic limit Subject RIV: BA - General Mathematics Impact factor: 0.373, year: 2014 http://aimsciences.org/journals/displayArticlesnew.jsp?paperID=9918

  19. Nonlinear Elasticity

    Science.gov (United States)

    Fu, Y. B.; Ogden, R. W.

    2001-05-01

    This collection of papers by leading researchers in the field of finite, nonlinear elasticity concerns itself with the behavior of objects that deform when external forces or temperature gradients are applied. This process is extremely important in many industrial settings, such as aerospace and rubber industries. This book covers the various aspects of the subject comprehensively with careful explanations of the basic theories and individual chapters each covering a different research direction. The authors discuss the use of symbolic manipulation software as well as computer algorithm issues. The emphasis is placed firmly on covering modern, recent developments, rather than the very theoretical approach often found. The book will be an excellent reference for both beginners and specialists in engineering, applied mathematics and physics.

  20. Nonlinear resonances

    CERN Document Server

    Rajasekar, Shanmuganathan

    2016-01-01

    This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

  1. Angiomatosis of bone and soft tissue: A spectrum of disease from diffuse lymphangiomatosis to vanishing bone disease in young patients

    International Nuclear Information System (INIS)

    Aviv, R.I.; McHugh, K.; Hunt, J.

    2001-01-01

    The application of cross-sectional imaging in the investigation of patients with angiomatosis reveals that lymphangiomatosis and vanishing bone disease should not be considered as separate entities, but rather as a spectrum of disease. We present a pictorial review of eight patients demonstrating the manifestations of soft tissue and bony involvement. We highlight a subgroup of patients with chyloid pleural effusions who have a poor prognosis. Aviv, R. I. et al. (2001)

  2. Analysis and numerical simulation of compressible two-phase flows using relaxation methods. Contribution to the treatment of vanishing phases

    International Nuclear Information System (INIS)

    Saleh, K.

    2012-01-01

    This thesis deals with the Baer-Nunziato two-phase flow model. The main objective of this work is to propose some techniques to cope with phase vanishing regimes which produce important instabilities in the model and its numerical simulations. Through analysis and simulation methods using Suliciu relaxation approximations, we prove that in these regimes, the solutions can be stabilised by introducing some extra dissipation of the total mixture entropy. In a first approach, called the Eulerian approach, the exact resolution of the relaxation Riemann problem provides an accurate entropy-satisfying numerical scheme, which turns out to be much more efficient in terms of CPU-cost than the classical and very simple Rusanov's scheme. Moreover, the scheme is proved to handle the vanishing phase regimes with great stability. The scheme, first developed in 1D, is then extended in 3D and implemented in an industrial code developed by EDF. The second approach, called the acoustic splitting approach, considers a separation of fast acoustic waves from slow material waves. The objective is to avoid the resonance due to the interaction between these two types of waves, and to allow an implicit treatment of the acoustics, while material waves are explicitly discretized. The resulting scheme is very simple and allows to deal simply with phase vanishing. The originality of this work is to use new dissipative closure laws for the interfacial velocity and pressure, in order to control the solutions of the Riemann problem associated with the acoustic step, in the phase vanishing regimes. (author)

  3. Is There a Role for Oral Antibiotic Preparation Alone Before Colorectal Surgery? ACS-NSQIP Analysis by Coarsened Exact Matching.

    Science.gov (United States)

    Garfinkle, Richard; Abou-Khalil, Jad; Morin, Nancy; Ghitulescu, Gabriela; Vasilevsky, Carol-Ann; Gordon, Philip; Demian, Marie; Boutros, Marylise

    2017-07-01

    Recent studies demonstrated reduced postoperative complications using combined mechanical bowel and oral antibiotic preparation before elective colorectal surgery. The aim of this study was to assess the impact of these 2 interventions on surgical site infections, anastomotic leak, ileus, major morbidity, and 30-day mortality in a large cohort of elective colectomies. This is a retrospective comparison of 30-day outcomes using the American College of Surgeons National Surgical Quality Improvement Program colectomy-targeted database with coarsened exact matching. Interventions were performed in hospitals participating in the national surgical database. Adult patients who underwent elective colectomy from 2012 to 2014 were included. Preoperative bowel preparations were evaluated. The primary outcomes measured were surgical site infections, anastomotic leak, postoperative ileus, major morbidity, and 30-day mortality. A total of 40,446 patients were analyzed: 13,219 (32.7%), 13,935 (34.5%), and 1572 (3.9%) in the no-preparation, mechanical bowel preparation alone, and oral antibiotic preparation alone groups, and 11,720 (29.0%) in the combined preparation group. After matching, 9800, 1461, and 8819 patients remained in the mechanical preparation, oral antibiotic preparation, and combined preparation groups for comparison with patients without preparation. On conditional logistic regression of matched patients, oral antibiotic preparation alone was protective of surgical site infection (OR, 0.63; 95% CI, 0.45-0.87), anastomotic leak (OR, 0.60; 95% CI, 0.34-0.97), ileus (OR, 0.79; 95% CI, 0.59-0.98), and major morbidity (OR, 0.73; 95% CI, 0.55-0.96), but not mortality (OR, 0.32; 95% CI, 0.08-1.18), whereas a regimen of combined oral antibiotics and mechanical bowel preparation was protective for all 5 major outcomes. When directly compared with oral antibiotic preparation alone, the combined regimen was not associated with any difference in any of the 5 postoperative

  4. Chaotic synchronization of two complex nonlinear oscillators

    International Nuclear Information System (INIS)

    Mahmoud, Gamal M.; Mahmoud, Emad E.; Farghaly, Ahmed A.; Aly, Shaban A.

    2009-01-01

    Synchronization is an important phenomenon commonly observed in nature. It is also often artificially induced because it is desirable for a variety of applications in physics, applied sciences and engineering. In a recent paper [Mahmoud GM, Mohamed AA, Aly SA. Strange attractors and chaos control in periodically forced complex Duffing's oscillators. Physica A 2001;292:193-206], a system of periodically forced complex Duffing's oscillators was introduced and shown to display chaotic behavior and possess strange attractors. Such complex oscillators appear in many problems of physics and engineering, as, for example, nonlinear optics, deep-water wave theory, plasma physics and bimolecular dynamics. Their connection to solutions of the nonlinear Schroedinger equation has also been pointed out. In this paper, we study the remarkable phenomenon of chaotic synchronization on these oscillator systems, using active control and global synchronization techniques. We derive analytical expressions for control functions and show that the dynamics of error evolution is globally stable, by constructing appropriate Lyapunov functions. This means that, for a relatively large set initial conditions, the differences between the drive and response systems vanish exponentially and synchronization is achieved. Numerical results are obtained to test the validity of the analytical expressions and illustrate the efficiency of these techniques for inducing chaos synchronization in our nonlinear oscillators.

  5. Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part II. Intermetallic Coarsening Behavior of Rapidly Solidified Solders After Multiple Reflows

    Science.gov (United States)

    Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

    2016-12-01

    Controlling the size, dispersion, and stability of intermetallic compounds in lead-free solder alloys is vital to creating reliable solder joints regardless of how many times the solder joints are melted and resolidified (reflowed) during circuit board assembly. In this article, the coarsening behavior of Cu x Al y and Cu6Sn5 in two Sn-Cu-Al alloys, a Sn-2.59Cu-0.43Al at. pct alloy produced via drip atomization and a Sn-5.39Cu-1.69Al at. pct alloy produced via melt spinning at a 5-m/s wheel speed, was characterized after multiple (1-5) reflow cycles via differential scanning calorimetry between the temperatures of 293 K and 523 K (20 °C and 250 °C). Little-to-no coarsening of the Cu x Al y particles was observed for either composition; however, clustering of Cu x Al y particles was observed. For Cu6Sn5 particle growth, a bimodal size distribution was observed for the drip atomized alloy, with large, faceted growth of Cu6Sn5 observed, while in the melt spun alloy, Cu6Sn5 particles displayed no significant increase in the average particle size, with irregularly shaped, nonfaceted Cu6Sn5 particles observed after reflow, which is consistent with shapes observed in the as-solidified alloys. The link between original alloy composition, reflow undercooling, and subsequent intermetallic coarsening behavior was discussed by using calculated solidification paths. The reflowed microstructures suggested that the heteroepitaxial relationship previously observed between the Cu x Al y and the Cu6Sn5 was maintained for both alloys.

  6. Multigrid Reduction in Time for Nonlinear Parabolic Problems

    Energy Technology Data Exchange (ETDEWEB)

    Falgout, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Manteuffel, T. A. [Univ. of Colorado, Boulder, CO (United States); O' Neill, B. [Univ. of Colorado, Boulder, CO (United States); Schroder, J. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-01-04

    The need for parallel-in-time is being driven by changes in computer architectures, where future speed-ups will be available through greater concurrency, but not faster clock speeds, which are stagnant.This leads to a bottleneck for sequential time marching schemes, because they lack parallelism in the time dimension. Multigrid Reduction in Time (MGRIT) is an iterative procedure that allows for temporal parallelism by utilizing multigrid reduction techniques and a multilevel hierarchy of coarse time grids. MGRIT has been shown to be effective for linear problems, with speedups of up to 50 times. The goal of this work is the efficient solution of nonlinear problems with MGRIT, where efficient is defined as achieving similar performance when compared to a corresponding linear problem. As our benchmark, we use the p-Laplacian, where p = 4 corresponds to a well-known nonlinear diffusion equation and p = 2 corresponds to our benchmark linear diffusion problem. When considering linear problems and implicit methods, the use of optimal spatial solvers such as spatial multigrid imply that the cost of one time step evaluation is fixed across temporal levels, which have a large variation in time step sizes. This is not the case for nonlinear problems, where the work required increases dramatically on coarser time grids, where relatively large time steps lead to worse conditioned nonlinear solves and increased nonlinear iteration counts per time step evaluation. This is the key difficulty explored by this paper. We show that by using a variety of strategies, most importantly, spatial coarsening and an alternate initial guess to the nonlinear time-step solver, we can reduce the work per time step evaluation over all temporal levels to a range similar with the corresponding linear problem. This allows for parallel scaling behavior comparable to the corresponding linear problem.

  7. Coarsening of (Fe, Cr)23C6 carbide phase on the tempering of 14Kh17N2 chromium-nickel steel

    International Nuclear Information System (INIS)

    Psarev, V.I.

    2002-01-01

    Paper lists the results of computer analysis of distribution according to sizes (Fe, Cr) 23 C 6 microparticles resulting from 14Kh17N2 steel tempering under 700 Deg C. Data were obtained at the maximum beneficial magnification of a light microscope. The mentioned curves of distribution densities are characterized by more reliable run from most permissible sizes of dispersed particles. Application of general rules of distributions and of previously elaborated procedure to identify experimental histograms with theoretical distributions enables to derive valuable information on dynamics of coarsening of a disperse phase in this case, as well [ru

  8. Strain-induced γ{sup '}-coarsening during aging of Ni-based superalloys under uniaxial load. Modeling and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mushongera, Leslie T.

    2016-07-28

    Turbine blades which are used in the hot paths of aerospace or industrial gas turbines are usually manufactured as casted single crystalline parts. However, even though grain boundaries are excluded, the degradation behavior of respectively developed single crystal nickel-base superalloys, is still quite complex involving a number of very different microscopic effects. One of these is the diffusion-limited coarsening of the γ{sup '}-precipitates. Long-term aging or creep loading along the <100> crystallographic orientation results in the anisotropic coarsening of the γ{sup '}-precipitates. In the end, the microstructure contains quite large, irregularly shaped precipitates or plate-like precipitates aligned either parallel (P-type rafts) or perpendicular (N-type rafts) to the loading direction. This behavior is detrimental for the properties of these materials since their superior properties emanate from the size, morphology and distribution of the γ{sup '}-precipitates [R. Reed: Cambridge University Press, (2006)]. In order to efficiently design these materials, the phenomenon of coarsening should be known in detail to optimize the materials accurately. On this background, the general objective of this thesis is to develop an integrated computational approach for simulating morphological evolution in single crystal Ni-base superalloys. As a first step towards that aim, a multi-component phase field model coupled to inputs from CALPHAD-type and kinetic databases for the relevant driving forces was developed based on the grand-potential formalism similar to Plapp [Phys. Rev. E, 84: 031601 (2011)]. The thermodynamic formulation of the model was validated by comparisons to ThermoCalc equilibrium calculations and DICTRA sharp-interface simulations. Phase field approaches that allow for anisotropies of the interfacial energy sufficiently high so that the interface develops sharp corners due to missing crystallographic orientations were formulated. This

  9. Short Communication on “Coarsening of Y-rich oxide particles in 9%Cr-ODS Eurofer steel annealed at 1350 °C”

    Energy Technology Data Exchange (ETDEWEB)

    Sandim, M.J.R.; Souza Filho, I.R.; Bredda, E.H. [Lorena School of Engineering, University of Sao Paulo, 12602-810, Lorena (Brazil); Kostka, A.; Raabe, D. [Max-Planck-Institut für Eisenforschung, D-40237, Düsseldorf (Germany); Sandim, H.R.Z., E-mail: hsandim@demar.eel.usp.br [Lorena School of Engineering, University of Sao Paulo, 12602-810, Lorena (Brazil)

    2017-02-15

    Oxide-dispersion strengthened (ODS) Eurofer steel is targeted for structural applications in future fusion nuclear reactors. Samples were cold rolled down to 80% reduction in thickness and annealed at 1350 °C up to 8 h. The microstructural characterization was performed using Vickers microhardness testing, electron backscatter diffraction, scanning and scanning transmission electron microscopies. Experimental results provide evidence of coarsening of the Y-rich oxide particles in ODS-Eurofer steel annealed at 1350 °C within delta ferrite phase field.

  10. Nonlinear sigma-models and their gauging in and out of superspace

    International Nuclear Information System (INIS)

    Hull, C.M.; California Univ., Santa Barbara; Karlhede, A.; Lindstroem, U.; Rocek, M.

    1986-01-01

    We analyze and generalize bosonic nonlinear sigma-models and their N=1,2 supersymmetric extensions in (4 spacetime-dimensional) N=1 superspace. We give a general construction of nonminimal kinetic terms for gauge fields and of N=1,2 gauging of isometries on Kaehler and hyper-Kaehler manifolds. In particular, we study the gauging of noncompact groups. We derive the complete component action and supertrace formula. For N=2 models, the supertrace always vanishes. (orig.)

  11. Isomorphism and the #betta#-function of the non-linear sigma model in symmetric spaces

    International Nuclear Information System (INIS)

    Hikami, S.

    1983-01-01

    The renormalization group #betta#-function of the non-linear sigma model in symmetric spaces is discussed via the isomorphic relation and the reciprocal relation about a parameter α. The four-loop term is investigated and the symmetric properties of the #betta#-function are studied. The four-loop term in the #betta#-function is shown to be vanishing for the orthogonal Anderson localization problem. (orig.)

  12. Spinor Field Nonlinearity and Space-Time Geometry

    Science.gov (United States)

    Saha, Bijan

    2018-03-01

    Within the scope of Bianchi type VI,VI0,V, III, I, LRSBI and FRW cosmological models we have studied the role of nonlinear spinor field on the evolution of the Universe and the spinor field itself. It was found that due to the presence of non-trivial non-diagonal components of the energy-momentum tensor of the spinor field in the anisotropic space-time, there occur some severe restrictions both on the metric functions and on the components of the spinor field. In this report we have considered a polynomial nonlinearity which is a function of invariants constructed from the bilinear spinor forms. It is found that in case of a Bianchi type-VI space-time, depending of the sign of self-coupling constants, the model allows either late time acceleration or oscillatory mode of evolution. In case of a Bianchi VI 0 type space-time due to the specific behavior of the spinor field we have two different scenarios. In one case the invariants constructed from bilinear spinor forms become trivial, thus giving rise to a massless and linear spinor field Lagrangian. This case is equivalent to the vacuum solution of the Bianchi VI 0 type space-time. The second case allows non-vanishing massive and nonlinear terms and depending on the sign of coupling constants gives rise to accelerating mode of expansion or the one that after obtaining some maximum value contracts and ends in big crunch, consequently generating space-time singularity. In case of a Bianchi type-V model there occur two possibilities. In one case we found that the metric functions are similar to each other. In this case the Universe expands with acceleration if the self-coupling constant is taken to be a positive one, whereas a negative coupling constant gives rise to a cyclic or periodic solution. In the second case the spinor mass and the spinor field nonlinearity vanish and the Universe expands linearly in time. In case of a Bianchi type-III model the space-time remains locally rotationally symmetric all the time

  13. Exact solutions of a nonpolynomially nonlinear Schrodinger equation

    International Nuclear Information System (INIS)

    Parwani, R.; Tan, H.S.

    2007-01-01

    A nonlinear generalisation of Schrodinger's equation had previously been obtained using information-theoretic arguments. The nonlinearities in that equation were of a nonpolynomial form, equivalent to the occurrence of higher-derivative nonlinear terms at all orders. Here we construct some exact solutions to that equation in 1+1 dimensions. On the half-line, the solutions resemble (exponentially damped) Bloch waves even though no external periodic potential is included. The solutions are nonperturbative as they do not reduce to solutions of the linear theory in the limit that the nonlinearity parameter vanishes. An intriguing feature of the solutions is their infinite degeneracy: for a given energy, there exists a very large arbitrariness in the normalisable wavefunctions. We also consider solutions to a q-deformed version of the nonlinear equation and discuss a natural discretisation implied by the nonpolynomiality. Finally, we contrast the properties of our solutions with other solutions of nonlinear Schrodinger equations in the literature and suggest some possible applications of our results in the domains of low-energy and high-energy physics

  14. Nonlinear mode coupling in rotating stars and the r-mode instability in neutron stars

    International Nuclear Information System (INIS)

    Schenk, A.K.; Arras, P.; Flanagan, E.E.; Teukolsky, S.A.; Wasserman, I.

    2002-01-01

    We develop the formalism required to study the nonlinear interaction of modes in rotating Newtonian stars, assuming that the mode amplitudes are only mildly nonlinear. The formalism is simpler than previous treatments of mode-mode interactions for spherical stars, and simplifies and corrects previous treatments for rotating stars. At linear order, we elucidate and extend slightly a formalism due to Schutz, show how to decompose a general motion of a rotating star into a sum over modes, and obtain uncoupled equations of motion for the mode amplitudes under the influence of an external force. Nonlinear effects are added perturbatively via three-mode couplings, which suffices for moderate amplitude modal excitations; the formalism is easy to extend to higher order couplings. We describe a new, efficient way to compute the modal coupling coefficients, to zeroth order in the stellar rotation rate, using spin-weighted spherical harmonics. The formalism is general enough to allow computation of the initial trends in the evolution of the spin frequency and differential rotation of the background star. We apply this formalism to derive some properties of the coupling coefficients relevant to the nonlinear interactions of unstable r modes in neutron stars, postponing numerical integrations of the coupled equations of motion to a later paper. First, we clarify some aspects of the expansion in stellar rotation frequency Ω that is often used to compute approximate mode functions. We show that, in zero-buoyancy stars, the rotational modes (those modes whose frequencies vanish as Ω→0) are orthogonal to zeroth order in Ω. From an astrophysical viewpoint, the most interesting result of this paper is that many couplings of r modes to other rotational modes are small: either they vanish altogether because of various selection rules, or they vanish to lowest order in Ω or in compressibility. In particular, in zero-buoyancy stars, the coupling of three r modes is forbidden

  15. Nonlinear beam mechanics

    NARCIS (Netherlands)

    Westra, H.J.R.

    2012-01-01

    In this Thesis, nonlinear dynamics and nonlinear interactions are studied from a micromechanical point of view. Single and doubly clamped beams are used as model systems where nonlinearity plays an important role. The nonlinearity also gives rise to rich dynamic behavior with phenomena like

  16. Vanishing current hysteresis under competing nuclear spin pumping processes in a quadruplet spin-blockaded double quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Amaha, S., E-mail: s-amaha@riken.jp [Quantum Spin Information Project, Japan Science and Technology Agency, ICORP, 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Quantum Functional System Research Group, RIKEN Center for Emergent Matter Science, RIKEN, 3-1 Wako-shi, Saitama 351-0198 (Japan); Hatano, T. [Quantum Spin Information Project, Japan Science and Technology Agency, ICORP, 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Department of Physics, Tohoku University, Sendai-shi, Miyagi 980-8578 (Japan); Tarucha, S. [Quantum Spin Information Project, Japan Science and Technology Agency, ICORP, 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Quantum Functional System Research Group, RIKEN Center for Emergent Matter Science, RIKEN, 3-1 Wako-shi, Saitama 351-0198 (Japan); Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Gupta, J. A.; Austing, D. G. [National Research Council of Canada, M50, Montreal Road, Ottawa, Ontario K1A 0R6 (Canada)

    2015-04-27

    We investigate nuclear spin pumping with five-electron quadruplet spin states in a spin-blockaded weakly coupled vertical double quantum dot device. Two types of hysteretic steps in the leakage current are observed on sweeping the magnetic field and are associated with bidirectional polarization of nuclear spin. Properties of the steps are understood in terms of bias-voltage-dependent conditions for the mixing of quadruplet and doublet spin states by the hyperfine interaction. The hysteretic steps vanish when up- and down-nuclear spin pumping processes are in close competition.

  17. Exponential vanishing of the ground-state gap of the quantum random energy model via adiabatic quantum computing

    Science.gov (United States)

    Adame, J.; Warzel, S.

    2015-11-01

    In this note, we use ideas of Farhi et al. [Int. J. Quantum. Inf. 6, 503 (2008) and Quantum Inf. Comput. 11, 840 (2011)] who link a lower bound on the run time of their quantum adiabatic search algorithm to an upper bound on the energy gap above the ground-state of the generators of this algorithm. We apply these ideas to the quantum random energy model (QREM). Our main result is a simple proof of the conjectured exponential vanishing of the energy gap of the QREM.

  18. Exponential vanishing of the ground-state gap of the quantum random energy model via adiabatic quantum computing

    International Nuclear Information System (INIS)

    Adame, J.; Warzel, S.

    2015-01-01

    In this note, we use ideas of Farhi et al. [Int. J. Quantum. Inf. 6, 503 (2008) and Quantum Inf. Comput. 11, 840 (2011)] who link a lower bound on the run time of their quantum adiabatic search algorithm to an upper bound on the energy gap above the ground-state of the generators of this algorithm. We apply these ideas to the quantum random energy model (QREM). Our main result is a simple proof of the conjectured exponential vanishing of the energy gap of the QREM

  19. Riemann-Cartan geometry of nonlinear disclination mechanics

    KAUST Repository

    Yavari, A.

    2012-03-23

    In the continuous theory of defects in nonlinear elastic solids, it is known that a distribution of disclinations leads, in general, to a non-trivial residual stress field. To study this problem, we consider the particular case of determining the residual stress field of a cylindrically symmetric distribution of parallel wedge disclinations. We first use the tools of differential geometry to construct a Riemannian material manifold in which the body is stress-free. This manifold is metric compatible, has zero torsion, but has non-vanishing curvature. The problem then reduces to embedding this manifold in Euclidean 3-space following the procedure of a classical nonlinear elastic problem. We show that this embedding can be elegantly accomplished by using Cartan\\'s method of moving frames and compute explicitly the residual stress field for various distributions in the case of a neo-Hookean material. © 2012 The Author(s).

  20. Nonlinear responses of chiral fluids from kinetic theory

    Science.gov (United States)

    Hidaka, Yoshimasa; Pu, Shi; Yang, Di-Lun

    2018-01-01

    The second-order nonlinear responses of inviscid chiral fluids near local equilibrium are investigated by applying the chiral kinetic theory (CKT) incorporating side-jump effects. It is shown that the local equilibrium distribution function can be nontrivially introduced in a comoving frame with respect to the fluid velocity when the quantum corrections in collisions are involved. For the study of anomalous transport, contributions from both quantum corrections in anomalous hydrodynamic equations of motion and those from the CKT and Wigner functions are considered under the relaxation-time (RT) approximation, which result in anomalous charge Hall currents propagating along the cross product of the background electric field and the temperature (or chemical-potential) gradient and of the temperature and chemical-potential gradients. On the other hand, the nonlinear quantum correction on the charge density vanishes in the classical RT approximation, which in fact satisfies the matching condition given by the anomalous equation obtained from the CKT.

  1. Testing and inference in nonlinear cointegrating vector error correction models

    DEFF Research Database (Denmark)

    Kristensen, D.; Rahbek, A.

    2013-01-01

    We analyze estimators and tests for a general class of vector error correction models that allows for asymmetric and nonlinear error correction. For a given number of cointegration relationships, general hypothesis testing is considered, where testing for linearity is of particular interest. Under...... the null of linearity, parameters of nonlinear components vanish, leading to a nonstandard testing problem. We apply so-called sup-tests to resolve this issue, which requires development of new(uniform) functional central limit theory and results for convergence of stochastic integrals. We provide a full...... asymptotic theory for estimators and test statistics. The derived asymptotic results prove to be nonstandard compared to results found elsewhere in the literature due to the impact of the estimated cointegration relations. This complicates implementation of tests motivating the introduction of bootstrap...

  2. Formation and propagation of sand dunes: A nonlinear treatment

    International Nuclear Information System (INIS)

    Eltayeb, I.A.; Hamza, E.A.; Hassan, M.H.A.

    1986-06-01

    The nonlinear evolutionary equations previously derived for a plane with a rigid lid are here generalized to the free surface model. It is shown that similar equations are obtainable but the coefficients are strongly dependent on the Froude number, F, of the flow. (F is defined as U/(gd) 1/2 , where U is the basic uniform flow, g the gravitational acceleration and d the mean depth of the layer.) When F vanishes, the evolutionary equations reduce to those derived previously for the rigid lid model. The equations possess a dunetrain solution. The stability of this solution is analyzed and found to depend crucially on F. It is found, however, that for all values of F a dunetrain can develop into a solitary dune. The above results apply only when the phase shift δ, originally introduced for the instability of the linear problem, vanishes. For other admissible values of δ, the analysis showed that the neutral solution of the linear theory prevails in the nonlinear regime. (author)

  3. A comparison of automatic and intentional instructions when using the method of vanishing cues in acquired brain injury.

    Science.gov (United States)

    Riley, Gerard A; Venn, Paul

    2015-01-01

    Thirty-four participants with acquired brain injury learned word lists under two forms of vanishing cues - one in which the learning trial instructions encouraged intentional retrieval (i.e., explicit memory) and one in which they encouraged automatic retrieval (which encompasses implicit memory). The automatic instructions represented a novel approach in which the cooperation of participants was actively sought to avoid intentional retrieval. Intentional instructions resulted in fewer errors during the learning trials and better performance on immediate and delayed retrieval tests. The advantage of intentional over automatic instructions was generally less for those who had more severe memory and/or executive impairments. Most participants performed better under intentional instructions on both the immediate and the delayed tests. Although those who were more severely impaired in both memory and executive function also did better with intentional instructions on the immediate retrieval test, they were significantly more likely to show an advantage for automatic instructions on the delayed test. It is suggested that this pattern of results may reflect impairments in the consolidation of intentional memories in this group. When using vanishing cues, automatic instructions may be better for those with severe consolidation impairments, but otherwise intentional instructions may be better.

  4. Dynamical vanishing of the order parameter in a confined Bardeen-Cooper-Schrieffer Fermi gas after an interaction quench

    Science.gov (United States)

    Hannibal, S.; Kettmann, P.; Croitoru, M. D.; Axt, V. M.; Kuhn, T.

    2018-01-01

    We present a numerical study of the Higgs mode in an ultracold confined Fermi gas after an interaction quench and find a dynamical vanishing of the superfluid order parameter. Our calculations are done within a microscopic density-matrix approach in the Bogoliubov-de Gennes framework which takes the three-dimensional cigar-shaped confinement explicitly into account. In this framework, we study the amplitude mode of the order parameter after interaction quenches starting on the BCS side of the BEC-BCS crossover close to the transition and ending in the BCS regime. We demonstrate the emergence of a dynamically vanishing superfluid order parameter in the spatiotemporal dynamics in a three-dimensional trap. Further, we show that the signal averaged over the whole trap mirrors the spatiotemporal behavior and allows us to systematically study the effects of the system size and aspect ratio on the observed dynamics. Our analysis enables us to connect the confinement-induced modifications of the dynamics to the pairing properties of the system. Finally, we demonstrate that the signature of the Higgs mode is contained in the dynamical signal of the condensate fraction, which, therefore, might provide a new experimental access to the nonadiabatic regime of the Higgs mode.

  5. Universality in an information-theoretic motivated nonlinear Schrodinger equation

    International Nuclear Information System (INIS)

    Parwani, R; Tabia, G

    2007-01-01

    Using perturbative methods, we analyse a nonlinear generalization of Schrodinger's equation that had previously been obtained through information-theoretic arguments. We obtain analytical expressions for the leading correction, in terms of the nonlinearity scale, to the energy eigenvalues of the linear Schrodinger equation in the presence of an external potential and observe some generic features. In one space dimension these are (i) for nodeless ground states, the energy shifts are subleading in the nonlinearity parameter compared to the shifts for the excited states; (ii) the shifts for the excited states are due predominantly to contribution from the nodes of the unperturbed wavefunctions, and (iii) the energy shifts for excited states are positive for small values of a regulating parameter and negative at large values, vanishing at a universal critical value that is not manifest in the equation. Some of these features hold true for higher dimensional problems. We also study two exactly solved nonlinear Schrodinger equations so as to contrast our observations. Finally, we comment on the possible significance of our results if the nonlinearity is physically realized

  6. Influence of Sm2O3 microalloying and Yb contamination on Y211 particles coarsening and superconducting properties of IG YBCO bulk superconductors

    Science.gov (United States)

    Vojtkova, L.; Diko, P.; Kovac, J.; Vojtko, M.

    2018-06-01

    Single grain YBa2Cu3O7‑x (YBCO or Y123) bulk superconductors were produced by an infiltration growth process. The solid phase precursor was prepared by solid state synthesis from Y2O3 + BaCuO2 powders. The influence of the addition of Sm2O3 and YB contamination from the substrate on the microstructure and superconducting properties was analyzed. The dependences of Yb concentration on the distance from the bottom of the samples measured by energy dispersive spectroscopy microanalysis used in conjunction with scanning electron microscopy confirmed the contamination of the samples during the melting stage of the sample preparation. It is shown that the addition of Sm in low concentration and its combination with Yb from the substrate modify the coarsening of the Y211 particles as well as lead to the appearance of a secondary peak effect in the field dependences of the critical current density.

  7. On structures developed by spinodal decomposition; the interpretation of the X-ray diffraction and the role of excess vacancies in the coarsening

    International Nuclear Information System (INIS)

    Keijser, Th. H. de

    1977-01-01

    Structures developed by spinodal decomposition in a AuPt (20-80) alloy were studied by X-ray diffraction. The structures consist of a quasi-periodic concentration modulation which causes a modulation of the lattice spacing in the cube directions. The modulation of the lattice spacing gives rise to the occurrence of side-bands in an X-ray diffraction pattern. Information on the nature of the modulation was deduced from the intensities of the side-bands. From the positions of the side-bands, the wavelength of the modulation was determined. The increase of the wavelength with aging time was investigated. Special attention was paid to the role of quenched-in excess vacancies in the coarsening process

  8. Aging and coarsening in isolated quantum systems after a quench: Exact results for the quantum O(N) model with N → ∞.

    Science.gov (United States)

    Maraga, Anna; Chiocchetta, Alessio; Mitra, Aditi; Gambassi, Andrea

    2015-10-01

    The nonequilibrium dynamics of an isolated quantum system after a sudden quench to a dynamical critical point is expected to be characterized by scaling and universal exponents due to the absence of time scales. We explore these features for a quench of the parameters of a Hamiltonian with O(N) symmetry, starting from a ground state in the disordered phase. In the limit of infinite N, the exponents and scaling forms of the relevant two-time correlation functions can be calculated exactly. Our analytical predictions are confirmed by the numerical solution of the corresponding equations. Moreover, we find that the same scaling functions, yet with different exponents, also describe the coarsening dynamics for quenches below the dynamical critical point.

  9. On Poisson Nonlinear Transformations

    Directory of Open Access Journals (Sweden)

    Nasir Ganikhodjaev

    2014-01-01

    Full Text Available We construct the family of Poisson nonlinear transformations defined on the countable sample space of nonnegative integers and investigate their trajectory behavior. We have proved that these nonlinear transformations are regular.

  10. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  11. Super-mercuryphobic and hydrophobic diamond surfaces with hierarchical structures: Vanishment of the contact angle hysteresis with mercury

    International Nuclear Information System (INIS)

    Escobar, Juan V.; Garza, Cristina; Alonso, Juan Carlos; Castillo, Rolando

    2013-01-01

    Increased roughness is known to enhance the natural wetting properties of surfaces, making them either more hydrophobic or more hydrophilic. In this work we study the wetting properties of water and mercury drops in contact with boron doped diamond films with progressively increased surface roughnesses. We show how thermal oxidation of a microcrystalline film creates pyramids decorated with sub-micron protrusions that turn its naturally mercuryphobic surface into super-mercuryphobic. With this liquid, we observe the vanishment of the contact angle hysteresis that is expected for rough surfaces as the contact angle approaches 180, making small drops of mercury roll along out of the surface at an apparent zero tilt-angle. In contrast, the incorporation of nano-globules on the oxidized surface through a silanization process is necessary to increase the hydrophobic properties of the film for which the contact angle with water reaches 138°. The wetting states that dominate in each case are discussed.

  12. Super-mercuryphobic and hydrophobic diamond surfaces with hierarchical structures: Vanishment of the contact angle hysteresis with mercury

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, Juan V., E-mail: escobar@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, PO Box 20-364, DF, México, 01000 (Mexico); Garza, Cristina, E-mail: cgarza@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, PO Box 20-364, DF, México, 01000 (Mexico); Alonso, Juan Carlos, E-mail: alonso@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, PO Box 70-360, DF, México, 04510 (Mexico); Castillo, Rolando, E-mail: rolandoc@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, PO Box 20-364, DF, México, 01000 (Mexico)

    2013-05-15

    Increased roughness is known to enhance the natural wetting properties of surfaces, making them either more hydrophobic or more hydrophilic. In this work we study the wetting properties of water and mercury drops in contact with boron doped diamond films with progressively increased surface roughnesses. We show how thermal oxidation of a microcrystalline film creates pyramids decorated with sub-micron protrusions that turn its naturally mercuryphobic surface into super-mercuryphobic. With this liquid, we observe the vanishment of the contact angle hysteresis that is expected for rough surfaces as the contact angle approaches 180, making small drops of mercury roll along out of the surface at an apparent zero tilt-angle. In contrast, the incorporation of nano-globules on the oxidized surface through a silanization process is necessary to increase the hydrophobic properties of the film for which the contact angle with water reaches 138°. The wetting states that dominate in each case are discussed.

  13. Office hysteroscopic treatment of a vanishing external uterine orifice in a postmenopausal woman with an obstetrical history of 44 abortions

    Directory of Open Access Journals (Sweden)

    Maurizio Guida

    2015-11-01

    Full Text Available Cervical stenosis, defined as cervical scarring of variable degree, represents a significant anatomical impediment to hysteroscopic procedures. Acquired cervical stenoses are more common than congenital forms and they are mainly associated with aging, estrogen–progesteron drugs, cervical trauma or carcinoma. The overcoming of cervical stenosis at office hysteroscopy is challenging and it often fails requiring the scheduling of the patient for an in-patient treatment under general anesthesia. We report the office hysteroscopy treatment of a vanishing external uterine orifice in a postmenopausal woman with an ultrasonographic report of a heterogeneous and thick endometrium suggestive of endometrial pathology, focusing on the main surgical steps to perform an adequate management.

  14. Vanishing honey bees: Is the dying of adult worker bees a consequence of short telomeres and premature aging?

    Science.gov (United States)

    Stindl, Reinhard; Stindl, Wolfgang

    2010-10-01

    Einstein is often quoted to have said that without the bee, mankind would have but 4years to live. It is highly unlikely that he made this comment, which was even mentioned in a Lancet article on honey bees. However, the current vanishing of the bees can have serious consequences for human health, because 35% of the human diet is thought to benefit from pollination. Colony collapse disorder (CCD) in honey bees is characterized by the rapid decline of the adult bee population, leaving the brood and the queen poorly or completely unattended, with no dead bodies in or around the hive. A large study found no evidence that the presence or amount of any individual pesticide or infectious agent occurred more frequently or abundantly in CCD-affected colonies. The growing consensus is that honey bees are suffering from comprised immune systems, which allow various infectious pathogens to invade. The question remains, what causes immunosuppression in many colonies of Apis mellifera in North America and Europe? Telomeres are protective DNA structures located at eukaryotic chromosome tips that shorten in the somatic tissues of animals with age. Lifelong tissue regeneration takes place in Apis mellifera, and worker bees have been shown to senesce. In humans, a vast amount of literature has accumulated on exhausted telomere reserves causing impaired tissue regeneration and age-associated diseases, specifically cancer and immunosuppression. Therefore, we propose a new causative mechanism for the vanishing of the bees: critically short telomeres in long-lived winter bees. We term this the telomere premature aging syndrome. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Quantum Nonlinear Optics

    CERN Document Server

    Hanamura, Eiichi; Yamanaka, Akio

    2007-01-01

    This graduate-level textbook gives an introductory overview of the fundamentals of quantum nonlinear optics. Based on the quantum theory of radiation, Quantum Nonlinear Optics incorporates the exciting developments in novel nonlinear responses of materials (plus laser oscillation and superradiance) developed over the past decade. It deals with the organization of radiation field, interaction between electronic system and radiation field, statistics of light, mutual manipulation of light and matter, laser oscillation, dynamics of light, nonlinear optical response, and nonlinear spectroscopy, as well as ultrashort and ultrastrong laser pulse. Also considered are Q-switching, mode locking and pulse compression. Experimental and theoretical aspects are intertwined throughout.

  16. Nonlinear dynamics and complexity

    CERN Document Server

    Luo, Albert; Fu, Xilin

    2014-01-01

    This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.

  17. Distributed nonlinear optical response

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov

    2005-01-01

    of bound states of out of phase bright solitons and dark solitons. Also, the newly introduced analogy between the nonlocal cubic nonlinear and the quadratic nonlinear media, presented in paper B and Chapter 3 is discussed. In particular it supplies intuitive physical meaning of the formation of solitons...... in quadratic nonlinear media. In the second part of the report (Chapter 4), the possibility to obtain light with ultrabroad spectrum due to the interplay of many nonlinear effects based on cubic nonlinearity is investigated thoroughly. The contribution of stimulated Raman scattering, a delayed nonlinear...... a modified nonlinear Schroedinger model equation. Chapter 4 and papers D and E are dedicated to this part of the research....

  18. Dynamics of solitons and quasisolitons of the cubic third-order nonlinear Schrödinger equation

    DEFF Research Database (Denmark)

    Karpman, V.I.; Juul Rasmussen, J.; Shagalov, A.G.

    2001-01-01

    The dynamics of soliton and quasisoliton solutions of the cubic third-order nonlinear Schrodinger equation is studied. Regular solitons exist due to a balance between the nonlinear terms and (linear) third-order dispersion; they are not important at small alpha (3) (alpha (3) is the coefficient...... in the third derivative term) and vanish at alpha3 -->0. The most essential, at small alpha (3), is a quasisoliton emitting resonant radiation (resonantly radiating soliton). Its relationship with the other (steady) quasisoliton, called embedded soliton, is studied analytically and also in numerical...

  19. Nonlinear Dirac Equations

    Directory of Open Access Journals (Sweden)

    Wei Khim Ng

    2009-02-01

    Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.

  20. Nonlinear graphene plasmonics

    Science.gov (United States)

    Ooi, Kelvin J. A.; Tan, Dawn T. H.

    2017-10-01

    The rapid development of graphene has opened up exciting new fields in graphene plasmonics and nonlinear optics. Graphene's unique two-dimensional band structure provides extraordinary linear and nonlinear optical properties, which have led to extreme optical confinement in graphene plasmonics and ultrahigh nonlinear optical coefficients, respectively. The synergy between graphene's linear and nonlinear optical properties gave rise to nonlinear graphene plasmonics, which greatly augments graphene-based nonlinear device performance beyond a billion-fold. This nascent field of research will eventually find far-reaching revolutionary technological applications that require device miniaturization, low power consumption and a broad range of operating wavelengths approaching the far-infrared, such as optical computing, medical instrumentation and security applications.

  1. Stationary nonlinear Airy beams

    International Nuclear Information System (INIS)

    Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.

    2011-01-01

    We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.

  2. Generalized Nonlinear Yule Models

    OpenAIRE

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-01-01

    With the aim of considering models with persistent memory we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macrovolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth...

  3. Nonlinear evolution equations

    CERN Document Server

    Uraltseva, N N

    1995-01-01

    This collection focuses on nonlinear problems in partial differential equations. Most of the papers are based on lectures presented at the seminar on partial differential equations and mathematical physics at St. Petersburg University. Among the topics explored are the existence and properties of solutions of various classes of nonlinear evolution equations, nonlinear imbedding theorems, bifurcations of solutions, and equations of mathematical physics (Navier-Stokes type equations and the nonlinear Schrödinger equation). The book will be useful to researchers and graduate students working in p

  4. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  5. Nonlinear optics at interfaces

    International Nuclear Information System (INIS)

    Chen, C.K.

    1980-12-01

    Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory

  6. Nonlinear drift tearing mode

    International Nuclear Information System (INIS)

    Zelenyj, L.M.; Kuznetsova, M.M.

    1989-01-01

    Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed

  7. Some current topics on nonlinear conservation laws lectures at the morningside center of mathematics, 1

    CERN Document Server

    Hsiao, Ling

    2000-01-01

    This volume resulted from a year-long program at the Morningside Center of Mathematics at the Academia Sinica in Beijing. It presents an overview of nonlinear conversation laws and introduces developments in this expanding field. Xin's introductory overview of the subject is followed by lecture notes of leading experts who have made fundamental contributions to this field of research. A. Bressan's theory of L^1-well-posedness for entropy weak solutions to systems of nonlinear hyperbolic conversation laws in the class of viscosity solutions is one of the most important results in the past two decades; G. Chen discusses weak convergence methods and various applications to many problems; P. Degond details mathematical modelling of semi-conductor devices; B. Perthame describes the theory of asymptotic equivalence between conservation laws and singular kinetic equations; Z. Xin outlines the recent development of the vanishing viscosity problem and nonlinear stability of elementary wave-a major focus of research in...

  8. Polarization Nonlinear Optics of Quadratically Nonlinear Azopolymers

    International Nuclear Information System (INIS)

    Konorov, S.O.; Akimov, D.A.; Ivanov, A.A.; Petrov, A.N.; Alfimov, M.V.; Yakimanskii, A.V.; Smirnov, N.N.; Ivanova, V.N.; Kudryavtsev, V.V.; Podshivalov, A.A.; Sokolova, I.M.; Zheltikov, A.M.

    2005-01-01

    The polarization properties of second harmonic and sum-frequency signals generated by femtosecond laser pulses in films of polymers containing covalent groups of an azobenzothiazole chromophore polarized by an external electric field are investigated. It is shown that the methods of polarization nonlinear optics make it possible to determine the structure of oriented molecular dipoles and reveal important properties of the motion of collectivized πelectrons in organic molecules with strong optical nonlinearities. The polarization measurements show that the tensor of quadratic nonlinear optical susceptibility of chromophore fragments oriented by an external field in macromolecules of the noted azopolymers has a degenerate form. This is indicative of a predominantly one-dimensional character of motion of collectivized π electrons along an extended group of atoms in such molecules

  9. Non-linear neutron star oscillations viewed as deviations from an equilibrium state

    International Nuclear Information System (INIS)

    Sperhake, U

    2002-01-01

    A numerical technique is presented which facilitates the evolution of non-linear neutron star oscillations with a high accuracy essentially independent of the oscillation amplitude. We apply this technique to radial neutron star oscillations in a Lagrangian formulation and demonstrate the superior performance of the new scheme compared with 'conventional' techniques. The key feature of our approach is to describe the evolution in terms of deviations from an equilibrium configuration. In contrast to standard perturbation analysis we keep all higher order terms in the evolution equations and thus obtain a fully non-linear description. The advantage of our scheme lies in the elimination of background terms from the equations and the associated numerical errors. The improvements thus achieved will be particularly significant in the study of mildly non-linear effects where the amplitude of the dynamic signal is small compared with the equilibrium values but large enough to warrant non-linear effects. We apply the new technique to the study of non-linear coupling of Eigenmodes and non-linear effects in the oscillations of marginally stable neutron stars. We find non-linear effects in low amplitude oscillations to be particularly pronounced in the range of modes with vanishing frequency which typically mark the onset of instability. (author)

  10. Fluctuations of two-time quantities and non-linear response functions

    International Nuclear Information System (INIS)

    Corberi, F; Lippiello, E; Sarracino, A; Zannetti, M

    2010-01-01

    We study the fluctuations of the autocorrelation and autoresponse functions and, in particular, their variances and covariance. In a first general part of the paper, we show the equivalence of the variance of the response function to the second-order susceptibility of a composite operator, and we derive an equilibrium fluctuation-dissipation theorem beyond linear order, relating it to the other variances. In a second part of the paper we apply the formalism in the study of non-disordered ferromagnets, in equilibrium or in the coarsening kinetics following a critical or sub-critical quench. We show numerically that the variances and the non-linear susceptibility obey scaling with respect to the coherence length ξ in equilibrium, and with respect to the growing length L(t) after a quench, similar to what is known for the autocorrelation and the autoresponse functions

  11. No need for a social cue! A masked magician can also trick the audience in the vanishing ball illusion.

    Science.gov (United States)

    Thomas, Cyril; Didierjean, André

    2016-01-01

    In the vanishing ball illusion (VBI), a magician throws a ball up in the air twice, after which he pretends to toss it up again, when in fact it remains secretly concealed in his hand. Observers perceive an imaginary ball disappearing into the air. According to Kuhn and Land (2006), the VBI during the fake throw is mediated by the magician's gaze and/or head direction (also called "social cues") as he looks toward the imaginary ball. The aim of this article is to test an alternative interpretation. According to our hypothesis, the magician's social cues are not essential to the VBI. We compared the numbers of participants experiencing the VBI when the magician's social cues were directed toward the illusory ball and when the magician's social cues were either hidden behind a black mask (Exp. 1) or stationary (Exp. 2). The results showed that the number of observers experiencing the VBI was high (almost two-thirds of the participants), regardless of whether the magician's social cueing was directed toward the illusion, hidden behind a mask, or stationary. In a third experiment (Exp. 3), we replicated Kuhn and Land's initial results and attempted to further explain their "anti-illusion" social-cue effect. This study confirms that social cueing is not required in the VBI: Its presence did not increase the number of participants experiencing the illusion.

  12. Simulation of the concomitant process of nucleation-growth-coarsening of Al2Cu particles in a 319 foundry aluminum alloy

    International Nuclear Information System (INIS)

    Martinez, R; Larouche, D; Cailletaud, G; Guillot, I; Massinon, D

    2015-01-01

    The precipitation of Al 2 Cu particles in a 319 T7 aluminum alloy has been modeled. A theoretical approach enables the concomitant computation of nucleation, growth and coarsening. The framework is based on an implicit scheme using the finite differences. The equation of continuity is discretized in time and space in order to obtain a matricial form. The inversion of a tridiagonal matrix gives way to determining the evolution of the size distribution of Al 2 Cu particles at t  +Δt. The fluxes of in-between the boundaries are computed in order to respect the conservation of the mass of the system, as well as the fluxes at the boundaries. The essential results of the model are compared to TEM measurements. Simulations provide quantitative features on the impact of the cooling rate on the size distribution of particles. They also provide results in agreement with the TEM measurements. This kind of multiscale approach allows new perspectives to be examined in the process of designing highly loaded components such as cylinder heads. It enables a more precise prediction of the microstructure and its evolution as a function of continuous cooling rates. (paper)

  13. Nonlinear sound generation by high energy particles

    International Nuclear Information System (INIS)

    Westervelt, P.J.

    1978-01-01

    In connection with Project DUMAND, the proposal to utilize the ocean as a giant acoustic detector of neutrinos, the applicability of a recent theory of thermoacoustic arrays [Peter J. Westervelt and Richard S. Larson, J. Acoust. Soc. Am. 54, 121 (1973)] is studied. In the static case or at very low frequencies, about 10% of the coefficient of thermal expansion for water at 20 0 C can be attributed to Debye-like modes. Debye-like modes generate sound via the nonlinear mechanism responsible for the operation of the parametric acoustic array [Peter J. Westervelt, J. Acoust. Soc. Am. 35, 535 (1963)]. The contribution of the Debye-like modes to the thermal expansion coefficient and thus to the sound pressure is essentially independent of the ambient water temperature. Hence if the Debye-like modes are not fully excited as is postulated to be the case at high frequencies, then the thermal expansion coefficient will be less than the static value by an amount that causes it to vanish at about 6 0 C instead of at 4 0 C, the temperature of maximum water density. This theory is in agreement with recent measurements of the temperature dependence of sound generated by proton deposition in water [L. Sulak, et al., Proceedings of the La Jolla Workshop on Acoustic Detection of Neutrinos, 25--29 July 1977, Scripps Institute of Oceanography, U.C.L.A., San Diego, Hugh Bradner, Ed.

  14. Nonlinear dynamics in Nuclotron

    International Nuclear Information System (INIS)

    Dinev, D.

    1997-01-01

    The paper represents an extensive study of the nonlinear beam dynamics in the Nuclotron. Chromatic effects, including the dependence of the betatron tunes on the amplitude, and chromatic perturbations have been investigated taking into account the measured field imperfections. Beam distortion, smear, dynamic aperture and nonlinear acceptance have been calculated for different particle energies and betatron tunes

  15. Nonlinear Optics and Applications

    Science.gov (United States)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  16. Paperless or vanishing society

    Science.gov (United States)

    Turner Luke, Joy

    2002-06-01

    In the 1940s color photography became available and within a few years, extremely popular. As people switched from black and white photographs made with the old metallic silver process to the new color films, pictures taken to record their lives and families began a slow disappearing act. The various color processes, coupled with the substrates they were printed on, affected their longevity, but many color photographs taken from the late 1950s through the 1970s, and even into the 1980s, faded not only when exposed to the light, but also when stored in the dark. Henry Wilhelm's excellent book 'The Permanence and Care of Color Photographs' documents this history in detail. Today we are making another transition in the storage of pictures and information. There are questions about the longevity of different types of digital storage, and also of the images printed by various types of inkjet printers, or by laser printers using colored toners. Very expensive and very beautiful works of art produced on Iris printers are appearing in art exhibitions. Some of these are referred to as Giclee prints and are offered on excellent papers. Artists are told the prints will last a lifetime; and if by change they don't it is only necessary to make another print. Henry Wilhelm has begun to test and rate these images for lightfastness; however, his test method was developed for examining longevity in colored photographs. It is of interest to find out how these prints will hold up in the tests required for fine art materials. Thus far companies producing digital inks and printers have not invested the time and money necessary to develop an American Society for Testing and Materials (ASTM) standard method for evaluating the lightfastness of digital prints. However, it is possible to use ASTM D 5383, Standard Practice for Visual Determination of the Lightfastness of Art Materials by Art Technologists, to pinpoint colors that will fade in a short time, even though the test is not as severe as ASTM D 4303, which is used to rate the lightfastness of artists's paint.

  17. Vanishing White Matter Disease

    Science.gov (United States)

    ... the ovaries, which can result in lack of menstrual periods, fertility problems and early menopause. Mental decline ... manner. This means that both parents carry one copy of a mutated eIF2B gene and pass it ...

  18. A Vanishing Act

    DEFF Research Database (Denmark)

    la Cour, Anders; Hecht, Janus; Stilling, Maria Kirstine

    2016-01-01

    The use of information and communication technology (ICT) has played an important role in the reforms that have taken place in Western welfare societies over the past two decades. ICT is regarded as a way to provide transparency and information exchange among providers, users and politicians....... This has also been the case for healthcare services in elderly home care, where ICT has been deployed to enable information exchange, knowledge sharing and documentation of delivered services. This article explores the extent to which the popular personal digital assistant (PDA) contributes to these types...... of activities in the provision of elderly home care services in Copenhagen, Denmark. We argue that despite the PDA’s promising potential to provide increased transparency concerning the delivery of services, it has had the opposite effect. Rather than creating transparency, the PDA has become a tool for hiding...

  19. Vanishing tumor in pregnancy

    Directory of Open Access Journals (Sweden)

    M V Vimal

    2012-01-01

    Full Text Available A patient with microprolactinoma, who had two successful pregnancies, is described for management issues. First pregnancy was uneventful. During the second pregnancy, the tumor enlarged to macroprolactinoma with headache and blurring of vision which was managed successfully with bromocriptine. Post delivery, complete disappearance of the tumor was documented.

  20. Vanishing tumor in pregnancy

    Science.gov (United States)

    Vimal, M. V.; Budyal, Sweta; Kasliwal, Rajeev; Jagtap, Varsha S.; Lila, Anurag R.; Bandgar, Tushar; Menon, Padmavathy; Shah, Nalini S.

    2012-01-01

    A patient with microprolactinoma, who had two successful pregnancies, is described for management issues. First pregnancy was uneventful. During the second pregnancy, the tumor enlarged to macroprolactinoma with headache and blurring of vision which was managed successfully with bromocriptine. Post delivery, complete disappearance of the tumor was documented. PMID:23226664

  1. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  2. Nonlinear Schroedinger equation with U(p,q) isotopical group

    International Nuclear Information System (INIS)

    Makhankov, V.G.; Pashaev, O.K.

    1981-01-01

    The properties of the nonlinear Schroedinger equation (NLS) with U(1,1) isogroup are considered in detail. This example illustrates the essential difference between the system and the well-known ''vector'' NLS, i.e. the large set of allowed boundary conditions on the fields that leads to a rich set of solutions of the system. Four types of boundary conditions and related soliton solutions are considered. The Bohr-Sommerfeld quantization allows to interpret them in terms of ''drops'' and ''bubbles'' as bound states of a large number of constituent bosons subject to the thermodynamical relations for gas mixtures. The U(1,1) system under the vanishing boundary conditions may be considered as continuous analog of the Hubbard model and therefore the paper is concluded by studying the inverse scattering equations for this case [ru

  3. Nonlinear effects of dark energy clustering beyond the acoustic scales

    International Nuclear Information System (INIS)

    Anselmi, Stefano; Nacir, Diana López; Sefusatti, Emiliano

    2014-01-01

    We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available

  4. Nonlinear effects of dark energy clustering beyond the acoustic scales

    Energy Technology Data Exchange (ETDEWEB)

    Anselmi, Stefano [Department of Physics/CERCA/ISO, Case Western Reserve University, Cleveland, OH 44106-7079 (United States); Nacir, Diana López [The Abdus Salam International Center for Theoretical Physics, Strada costiera 11, I-34151 Trieste (Italy); Sefusatti, Emiliano, E-mail: stefano.anselmi@case.edu, E-mail: dlopez_n@ictp.it, E-mail: emiliano.sefusatti@brera.inaf.it [INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Saint Lucia) (Italy)

    2014-07-01

    We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available.

  5. Nonlinear photonic metasurfaces

    Science.gov (United States)

    Li, Guixin; Zhang, Shuang; Zentgraf, Thomas

    2017-03-01

    Compared with conventional optical elements, 2D photonic metasurfaces, consisting of arrays of antennas with subwavelength thickness (the 'meta-atoms'), enable the manipulation of light-matter interactions on more compact platforms. The use of metasurfaces with spatially varying arrangements of meta-atoms that have subwavelength lateral resolution allows control of the polarization, phase and amplitude of light. Many exotic phenomena have been successfully demonstrated in linear optics; however, to meet the growing demand for the integration of more functionalities into a single optoelectronic circuit, the tailorable nonlinear optical properties of metasurfaces will also need to be exploited. In this Review, we discuss the design of nonlinear photonic metasurfaces — in particular, the criteria for choosing the materials and symmetries of the meta-atoms — for the realization of nonlinear optical chirality, nonlinear geometric Berry phase and nonlinear wavefront engineering. Finally, we survey the application of nonlinear photonic metasurfaces in optical switching and modulation, and we conclude with an outlook on their use for terahertz nonlinear optics and quantum information processing.

  6. Nonlinear crack mechanics

    International Nuclear Information System (INIS)

    Khoroshun, L.P.

    1995-01-01

    The characteristic features of the deformation and failure of actual materials in the vicinity of a crack tip are due to their physical nonlinearity in the stress-concentration zone, which is a result of plasticity, microfailure, or a nonlinear dependence of the interatomic forces on the distance. Therefore, adequate models of the failure mechanics must be nonlinear, in principle, although linear failure mechanics is applicable if the zone of nonlinear deformation is small in comparison with the crack length. Models of crack mechanics are based on analytical solutions of the problem of the stress-strain state in the vicinity of the crack. On account of the complexity of the problem, nonlinear models are bason on approximate schematic solutions. In the Leonov-Panasyuk-Dugdale nonlinear model, one of the best known, the actual two-dimensional plastic zone (the nonlinearity zone) is replaced by a narrow one-dimensional zone, which is then modeled by extending the crack with a specified normal load equal to the yield point. The condition of finite stress is applied here, and hence the length of the plastic zone is determined. As a result of this approximation, the displacement in the plastic zone at the abscissa is nonzero

  7. Palaeolimnological evidence of vulnerability of Lake Neusiedl (Austria) toward climate related changes since the last "vanished-lake" stage.

    Science.gov (United States)

    Tolotti, Monica; Milan, Manuela; Boscaini, Adriano; Soja, Gerhard; Herzig, Alois

    2013-04-01

    The palaeolimnological reconstruction of secular evolution of Euroepan Lakes with key socio-economical relevance respect to large (climate change) and local scale (land use, tourism) environmental changes, represents one of the objectives of the project EuLakes (European Lakes Under Environmental Stressors, Supporting lake governance to mitigate the impact of climate change, Reg. N. 2CE243P3), launched in 2010 within the Central European Inititiative. The project consortium comprises lakes of different morphology and prevalent human uses, including the meso-eutrophic Lake Neusiedl, the largest Austrian lake (total area 315 km2), and the westernmost shallow (mean depth 1.2 m) steppe lake of the Euro-Asiatic continent. The volume of Lake Neusiedl can potentially change over the years, in relation with changing balance between atmospheric precipitation and lake water evapotranspiration. Changing water budget, together with high lake salinity and turbidity, have important implications over the lake ecosystem. This contribution illustrates results of the multi-proxi palaeolimnological reconstruction of ecologial changes occurred in Lake Neusiedl during the last ca. 140 years, i.e. since the end of the last "vanished-lake" stage (1865-1871). Geochemical and biological proxies anticipate the increase in lake productivity of ca. 10 years (1950s) respect to what reported in the literature. Diatom species composition indicate a biological lake recovery in the late 1980s, and suggest a second increment in lake productivity since the late 1990s, possibly in relation with the progressive increase in the nitrogen input from agriculture. Abundance of diatoms typical of brackish waters indicated no significant long-term change in lake salinity, while variations in species toleranting dessiccation confirm the vulnerability of Lake Neusiedl toward climate-driven changes in the lake water balance. This fragility is aggravated by the the semi-arid climate conditions of the catchemnt

  8. Effects of intermode nonlinearity and intramode nonlinearity on modulation instability in randomly birefringent two-mode optical fibers

    Science.gov (United States)

    Li, Jin Hua; Xu, Hui; Sun, Ting Ting; Pei, Shi Xin; Ren, Hai Dong

    2018-05-01

    We analyze in detail the effects of the intermode nonlinearity (IEMN) and intramode nonlinearity (IRMN) on modulation instability (MI) in randomly birefringent two-mode optical fibers (RB-TMFs). In the anomalous dispersion regime, the MI gain enhances significantly as the IEMN and IRMN coefficients increases. In the normal dispersion regime, MI can be generated without the differential mode group delay (DMGD) effect, as long as the IEMN coefficient between two distinct modes is above a critical value, or the IRMN coefficient inside a mode is below a critical value. This critical IEMN (IRMN) coefficient depends strongly on the given IRMN (IEMN) coefficient and DMGD for a given nonlinear RB-TMF structure, and is independent on the input total power, the power ratio distribution and the group velocity dispersion (GVD) ratio between the two modes. On the other hand, in contrast to the MI band arising from the pure effect of DMGD in the normal dispersion regime, where MI vanishes after a critical total power, the generated MI band under the combined effects of IEMN and IRMN without DMGD exists for any total power and enhances with the total power. The MI analysis is verified numerically by launching perturbed continuous waves (CWs) with wave propagation method.

  9. Nonlinear wave equations

    CERN Document Server

    Li, Tatsien

    2017-01-01

    This book focuses on nonlinear wave equations, which are of considerable significance from both physical and theoretical perspectives. It also presents complete results on the lower bound estimates of lifespan (including the global existence), which are established for classical solutions to the Cauchy problem of nonlinear wave equations with small initial data in all possible space dimensions and with all possible integer powers of nonlinear terms. Further, the book proposes the global iteration method, which offers a unified and straightforward approach for treating these kinds of problems. Purely based on the properties of solut ions to the corresponding linear problems, the method simply applies the contraction mapping principle.

  10. Super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging

    Science.gov (United States)

    Wei, Lu; Zhu, Xinxin; Chen, Zhixing; Min, Wei

    2014-02-01

    Two-photon excited fluorescence microscopy (TPFM) offers the highest penetration depth with subcellular resolution in light microscopy, due to its unique advantage of nonlinear excitation. However, a fundamental imaging-depth limit, accompanied by a vanishing signal-to-background contrast, still exists for TPFM when imaging deep into scattering samples. Formally, the focusing depth, at which the in-focus signal and the out-of-focus background are equal to each other, is defined as the fundamental imaging-depth limit. To go beyond this imaging-depth limit of TPFM, we report a new class of super-nonlinear fluorescence microscopy for high-contrast deep tissue imaging, including multiphoton activation and imaging (MPAI) harnessing novel photo-activatable fluorophores, stimulated emission reduced fluorescence (SERF) microscopy by adding a weak laser beam for stimulated emission, and two-photon induced focal saturation imaging with preferential depletion of ground-state fluorophores at focus. The resulting image contrasts all exhibit a higher-order (third- or fourth- order) nonlinear signal dependence on laser intensity than that in the standard TPFM. Both the physical principles and the imaging demonstrations will be provided for each super-nonlinear microscopy. In all these techniques, the created super-nonlinearity significantly enhances the imaging contrast and concurrently extends the imaging depth-limit of TPFM. Conceptually different from conventional multiphoton processes mediated by virtual states, our strategy constitutes a new class of fluorescence microscopy where high-order nonlinearity is mediated by real population transfer.

  11. Photostable nonlinear optical polycarbonates

    NARCIS (Netherlands)

    Faccini, M.; Balakrishnan, M.; Diemeer, Mart; Torosantucci, Riccardo; Driessen, A.; Reinhoudt, David; Verboom, Willem

    2008-01-01

    Highly thermal and photostable nonlinear optical polymers were obtained by covalently incorporating the tricyanovinylidenediphenylaminobenzene (TCVDPA) chromophore to a polycarbonate backbone. NLO polycarbonates with different chromophore attachment modes and flexibilities were synthesized. In spite

  12. Nonlinear singular elliptic equations

    International Nuclear Information System (INIS)

    Dong Minh Duc.

    1988-09-01

    We improve the Poincare inequality, the Sobolev imbedding theorem and the Trudinger imbedding theorem and prove a Mountain pass theorem. Applying these results we study a nonlinear singular mixed boundary problem. (author). 22 refs

  13. Nonlinear Optical Terahertz Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — We develop a new approach to generation of THz radiation. Our method relies on mixing two optical frequency beams in a nonlinear crystalline Whispering Gallery Mode...

  14. Nonlinear differential equations

    CERN Document Server

    Struble, Raimond A

    2017-01-01

    Detailed treatment covers existence and uniqueness of a solution of the initial value problem, properties of solutions, properties of linear systems, stability of nonlinear systems, and two-dimensional systems. 1962 edition.

  15. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...... to a decrease of plasma frequency in semiconductor and produces a substantial modification of THz-range material dielectric function, described by the Drude model. As a result, the nonlinearity of both absorption coefficient and refractive index of the semiconductor is observed. In particular we demonstrate...

  16. Ultrafast nonlinear optics

    CERN Document Server

    Leburn, Christopher; Reid, Derryck

    2013-01-01

    The field of ultrafast nonlinear optics is broad and multidisciplinary, and encompasses areas concerned with both the generation and measurement of ultrashort pulses of light, as well as those concerned with the applications of such pulses. Ultrashort pulses are extreme events – both in terms of their durations, and also the high peak powers which their short durations can facilitate. These extreme properties make them powerful experiment tools. On one hand, their ultrashort durations facilitate the probing and manipulation of matter on incredibly short timescales. On the other, their ultrashort durations can facilitate high peak powers which can drive highly nonlinear light-matter interaction processes. Ultrafast Nonlinear Optics covers a complete range of topics, both applied and fundamental in nature, within the area of ultrafast nonlinear optics. Chapters 1 to 4 are concerned with the generation and measurement of ultrashort pulses. Chapters 5 to 7 are concerned with fundamental applications of ultrasho...

  17. Nonlinear surface Alfven waves

    International Nuclear Information System (INIS)

    Cramer, N.F.

    1991-01-01

    The problem of nonlinear surface Alfven waves propagating on an interface between a plasma and a vacuum is discussed, with dispersion provided by the finite-frequency effect, i.e. the finite ratio of the frequency to the ion-cyclotron frequency. A set of simplified nonlinear wave equations is derived using the method of stretched co-ordinates, and another approach uses the generation of a second-harmonic wave and its interaction with the first harmonic to obtain a nonlinear dispersion relation. A nonlinear Schroedinger equation is then derived, and soliton solutions found that propagate as solitary pulses in directions close to parallel and antiparallel to the background magnetic field. (author)

  18. Nonlinear Structural Analysis

    Indian Academy of Sciences (India)

    The Structures Panel of the Aeronautics Research and Development Board of India ... A great variety of topics was covered, including themes such as nonlinear finite ... or shell structures, and three are on the composite form of construction, ...

  19. A nonlinear oscillatory problem

    International Nuclear Information System (INIS)

    Zhou Qingqing.

    1991-10-01

    We have studied the nonlinear oscillatory problem of orthotropic cylindrical shell, we have analyzed the character of the oscillatory system. The stable condition of the oscillatory system has been given. (author). 6 refs

  20. Introduction to nonlinear science

    CERN Document Server

    Nicolis, G

    1995-01-01

    One of the most unexpected results in science in recent years is that quite ordinary systems obeying simple laws can give rise to complex, nonlinear or chaotic, behavior. In this book, the author presents a unified treatment of the concepts and tools needed to analyze nonlinear phenomena and to outline some representative applications drawn from the physical, engineering, and biological sciences. Some of the interesting topics covered include: dynamical systems with a finite number of degrees of freedom, linear stability analysis of fixed points, nonlinear behavior of fixed points, bifurcation analysis, spatially distributed systems, broken symmetries, pattern formation, and chaotic dynamics. The author makes a special effort to provide a logical connection between ordinary dynamical systems and spatially extended systems, and to balance the emphasis on chaotic behavior and more classical nonlinear behavior. He also develops a statistical approach to complex systems and compares it to traditional deterministi...

  1. Nonlinear Wave Propagation

    Science.gov (United States)

    2015-05-07

    associated with the lattice background; the nonlinearity is derived from the inclusion of cubic nonlinearity. Often the background potential is periodic...dispersion branch we can find discrete evolution equations for the envelope associated with the lattice NLS equation (1) by looking for solutions of...spatial operator in the above NLS equation can be elliptic, hyperbolic or parabolic . We remark that further reduction is possible by going into a moving

  2. Nonlinear dynamics and astrophysics

    International Nuclear Information System (INIS)

    Vallejo, J. C.; Sanjuan, M. A. F.

    2000-01-01

    Concepts and techniques from Nonlinear Dynamics, also known as Chaos Theory, have been applied successfully to several astrophysical fields such as orbital motion, time series analysis or galactic dynamics, providing answers to old questions but also opening a few new ones. Some of these topics are described in this review article, showing the basis of Nonlinear Dynamics, and how it is applied in Astrophysics. (Author)

  3. On the vanishing of multiloop contributions to the 0-, 1-, 2-, 3-point functions in the Green-Schwarz formalism for heterotic strings

    International Nuclear Information System (INIS)

    Kallosh, R.; Morosov, A.

    1988-01-01

    We analyse the structure of insertions arising in multiloop calculations in the first-quantized version of the Green-Schwarz formalism. We show that at least four constant zero modes of grassmannian Θ-fields related to space-time supersymmetry are not removed by insertions. The occurrence of these zero modes straightforwardly leads to non-renormalization theorems, which imply that all 0-, 1-, 2-, 3-point functions vanish. (orig.)

  4. Vanishing Lung Syndrome: Compound Effect of Tobacco and Marijuana Use on the Development of Bullous Lung Disease – A Joint Effort

    OpenAIRE

    Wiesel, Shimshon; Siddiqui, Faraz; Khan, Tahir; Hossri, Sami; El-Sayegh, Dany

    2017-01-01

    Marijuana use has been increasing across the United States due to its legalization as both a medicinal and recreational product. A small number of case reports have described a pathological entity called vanishing lung syndrome (VLS), which is a rare bullous lung disease usually caused by tobacco smoking. Recent case reports have implicated marijuana in the development of VLS. We present a case of a 47-year-old man, who presented to our hospital with shortness of breath, fevers and a producti...

  5. Pescara benchmarks: nonlinear identification

    Science.gov (United States)

    Gandino, E.; Garibaldi, L.; Marchesiello, S.

    2011-07-01

    Recent nonlinear methods are suitable for identifying large systems with lumped nonlinearities, but in practice most structural nonlinearities are distributed and an ideal nonlinear identification method should cater for them as well. In order to extend the current NSI method to be applied also on realistic large engineering structures, a modal counterpart of the method is proposed in this paper. The modal NSI technique is applied on one of the reinforced concrete beams that have been tested in Pescara, under the project titled "Monitoring and diagnostics of railway bridges by means of the analysis of the dynamic response due to train crossing", financed by Italian Ministry of Research. The beam showed a softening nonlinear behaviour, so that the nonlinearity concerning the first mode is characterized and its force contribution is quantified. Moreover, estimates for the modal parameters are obtained and the model is validated by comparing the measured and the reconstructed output. The identified estimates are also used to accurately predict the behaviour of the same beam, when subject to different initial conditions.

  6. Nonlinear Multiantenna Detection Methods

    Directory of Open Access Journals (Sweden)

    Chen Sheng

    2004-01-01

    Full Text Available A nonlinear detection technique designed for multiple-antenna assisted receivers employed in space-division multiple-access systems is investigated. We derive the optimal solution of the nonlinear spatial-processing assisted receiver for binary phase shift keying signalling, which we refer to as the Bayesian detector. It is shown that this optimal Bayesian receiver significantly outperforms the standard linear beamforming assisted receiver in terms of a reduced bit error rate, at the expense of an increased complexity, while the achievable system capacity is substantially enhanced with the advent of employing nonlinear detection. Specifically, when the spatial separation expressed in terms of the angle of arrival between the desired and interfering signals is below a certain threshold, a linear beamformer would fail to separate them, while a nonlinear detection assisted receiver is still capable of performing adequately. The adaptive implementation of the optimal Bayesian detector can be realized using a radial basis function network. Two techniques are presented for constructing block-data-based adaptive nonlinear multiple-antenna assisted receivers. One of them is based on the relevance vector machine invoked for classification, while the other on the orthogonal forward selection procedure combined with the Fisher ratio class-separability measure. A recursive sample-by-sample adaptation procedure is also proposed for training nonlinear detectors based on an amalgam of enhanced -means clustering techniques and the recursive least squares algorithm.

  7. Pescara benchmarks: nonlinear identification

    International Nuclear Information System (INIS)

    Gandino, E; Garibaldi, L; Marchesiello, S

    2011-01-01

    Recent nonlinear methods are suitable for identifying large systems with lumped nonlinearities, but in practice most structural nonlinearities are distributed and an ideal nonlinear identification method should cater for them as well. In order to extend the current NSI method to be applied also on realistic large engineering structures, a modal counterpart of the method is proposed in this paper. The modal NSI technique is applied on one of the reinforced concrete beams that have been tested in Pescara, under the project titled M onitoring and diagnostics of railway bridges by means of the analysis of the dynamic response due to train crossing , financed by Italian Ministry of Research. The beam showed a softening nonlinear behaviour, so that the nonlinearity concerning the first mode is characterized and its force contribution is quantified. Moreover, estimates for the modal parameters are obtained and the model is validated by comparing the measured and the reconstructed output. The identified estimates are also used to accurately predict the behaviour of the same beam, when subject to different initial conditions.

  8. Introduction to nonlinear acoustics

    Science.gov (United States)

    Bjørnø, Leif

    2010-01-01

    A brief review of the basic principles of fluid mechanics needed for development of linear and nonlinear ultrasonic concepts will be given. The fundamental equations of nonlinear ultrasonics will be derived and their physical properties explained. It will be shown how an originally monochromatic finite-amplitude ultrasonic wave, due to nonlinear effects, will distort during its propagation in time and space to form higher harmonics to its fundamental frequency. The concepts of shock formation will be presented. The material nonlinearity, described by the nonlinearity parameter B/A of the material, and the convective nonlinearity, described by the ultrasonic Mach Number, will be explained. Two procedures for determination of B/A will briefly be described and some B/A-values characterizing biological materials will be presented. Shock formation, described by use of the Goldberg Number,and Ultrasonic Saturation will be discussed.. An introduction to focused ultrasonic fields will be given and it will be shown how the ultrasonic intensity will vary axially and laterally in and near the focal region and how the field parameters of interest to biomedical applications may be described by use of the KZK-Model. Finally, an introduction will be given to the parametric acoustic array formed by mixing and interaction of two monochromatic, finite-amplitude ultrasonic waves in a liquid and the potentials of this mixing process in biomedical ultrasound will briefly be mentioned.

  9. Fundamentals of nonlinear optical materials

    Indian Academy of Sciences (India)

    Nonlinear optics; nonlinear polarization; optical fiber communication; optical switch- ing. PACS Nos 42.65Tg; ... The importance of nonlinear optics is to understand the nonlinear behavior in the induced polarization and to ..... but much work in material development and characterization remains to be done. 16. Conclusion.

  10. Nonlinear Approaches in Engineering Applications

    CERN Document Server

    Jazar, Reza

    2012-01-01

    Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...

  11. 50 years of nonlinear optics

    International Nuclear Information System (INIS)

    Shen Yuanrang

    2011-01-01

    This article presents a brief introduction to the birth and early investigations of nonlinear optics, such as second harmonic generation,sum and difference frequency generation, stimulated Raman scattering,and self-action of light etc. Several important research achievements and applications of nonlinear optics are presented as well, including nonlinear optical spectroscopy, phase conjugation and adaptive optics, coherent nonlinear optics, and high-order harmonic generation. In the end, current and future research topics in nonlinear optics are summarized. (authors)

  12. Rational solitons in the parity-time-symmetric nonlocal nonlinear Schrödinger model

    International Nuclear Information System (INIS)

    Li Min; Xu Tao; Meng Dexin

    2016-01-01

    In this paper, via the generalized Darboux transformation, rational soliton solutions are derived for the parity-time-symmetric nonlocal nonlinear Schrödinger (NLS) model with the defocusing-type nonlinearity. We find that the first-order solution can exhibit the elastic interactions of rational antidark-antidark, dark-antidark, and antidark-dark soliton pairs on a continuous wave background, but there is no phase shift for the interacting solitons. Also, we discuss the degenerate case in which only one rational dark or antidark soliton survives. Moreover, we reveal that the second-order rational solution displays the interactions between two solitons with combined-peak-valley structures in the near-field regions, but each interacting soliton vanishes or evolves into a rational dark or antidark soliton as |z| → ∞. In addition, we numerically examine the stability of the first- and second-order rational soliton solutions. (author)

  13. Theory of nonlinear harmonic generation in free-electron lasers with helical wigglers

    International Nuclear Information System (INIS)

    Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

    2007-05-01

    CoherentHarmonicGeneration (CHG), and in particularNonlinearHarmonicGeneration (NHG), is of importance for both short wavelength Free-Electron Lasers (FELs), in relation with the achievement of shorter wavelengths with a fixed electron-beam energy, and high-average power FEL resonators, in relation with destructive effects of higher harmonics radiation on mirrors. In this paper we present a treatment of NHG from helical wigglers with particular emphasis on the second harmonic. Our study is based on an exact analytical solution of Maxwell's equations, derived with the help of a Green's function method. In particular, we demonstrate that nonlinear harmonic generation (NHG) fromhelicalwigglers vanishes on axis. Our conclusion is in open contrast with results in literature, that include a kinematical mistake in the description of the electron motion. (orig.)

  14. Enhancement of the nonlinear optical absorption of the E7 liquid crystal at the nematic-isotropic transition

    International Nuclear Information System (INIS)

    Gomez, S.L.; Lenart, V.M.; Bechtold, I.H.; Figueiredo Neto, A.M.

    2012-01-01

    We present an experimental study of the nonlinear optical absorption of the eutectic mixture E7 at the nematic-isotropic phase transition by the Z-scan technique, under continuous-wave excitation at 532 nm. In the nematic region, the effective nonlinear optical coefficient P, which vanishes in the isotropic phase, is negative for the extraordinary beam and positive for an ordinary beam. The parameter SNL, whose definition in terms of the nonlinear absorption coefficient follows the definition of the optical-order parameter in terms of the linear dichroic ratio, behaves like an order parameter with critical exponent 0.22 ± 0.05, in good agreement with the tricritical hypothesis for the nematic isotropic transition. (author)

  15. Nonlinear dynamics of structures

    CERN Document Server

    Oller, Sergio

    2014-01-01

    This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics.   This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects.   Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution  are studied, and the theoretical concepts and its programming algorithms are presented.  

  16. Nonlinear Dot Plots.

    Science.gov (United States)

    Rodrigues, Nils; Weiskopf, Daniel

    2018-01-01

    Conventional dot plots use a constant dot size and are typically applied to show the frequency distribution of small data sets. Unfortunately, they are not designed for a high dynamic range of frequencies. We address this problem by introducing nonlinear dot plots. Adopting the idea of nonlinear scaling from logarithmic bar charts, our plots allow for dots of varying size so that columns with a large number of samples are reduced in height. For the construction of these diagrams, we introduce an efficient two-way sweep algorithm that leads to a dense and symmetrical layout. We compensate aliasing artifacts at high dot densities by a specifically designed low-pass filtering method. Examples of nonlinear dot plots are compared to conventional dot plots as well as linear and logarithmic histograms. Finally, we include feedback from an expert review.

  17. Multidimensional nonlinear descriptive analysis

    CERN Document Server

    Nishisato, Shizuhiko

    2006-01-01

    Quantification of categorical, or non-numerical, data is a problem that scientists face across a wide range of disciplines. Exploring data analysis in various areas of research, such as the social sciences and biology, Multidimensional Nonlinear Descriptive Analysis presents methods for analyzing categorical data that are not necessarily sampled randomly from a normal population and often involve nonlinear relations. This reference not only provides an overview of multidimensional nonlinear descriptive analysis (MUNDA) of discrete data, it also offers new results in a variety of fields. The first part of the book covers conceptual and technical preliminaries needed to understand the data analysis in subsequent chapters. The next two parts contain applications of MUNDA to diverse data types, with each chapter devoted to one type of categorical data, a brief historical comment, and basic skills peculiar to the data types. The final part examines several problems and then concludes with suggestions for futu...

  18. Nonlinear Source Emulator

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem

    of a proposed NSE system with high dynamic performance. The goal of the work is to achieve a state-of-the art transient time of 10 µs. In order to produce the arbitrary nonlinear curve, the exponential function of a typical diode is used, but the diode can be replaced by other nonlinear curve reference...... of conductive common-mode current produced by the high rate of change of voltage over time (high dv/dt) at the NSE output. v/xvii The contributions of the thesis are based on the development of both units: the low Cio isolated power supply and the high dynamic performance NSE. Both units are investigated......-of-the-art dynamic performance among devices of the same kind. It also offers a complete solution for simulation of nonlinear source systems of different sizes, both in terrestrial and non-terrestrial applications. Key words: Current transformers, dc-dc power converters, hysteresis, parasitic capacitance, system...

  19. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  20. Nonlinear excitations in biomolecules

    International Nuclear Information System (INIS)

    Peyrard, M.

    1995-01-01

    The aim of the workshop entitled ''Nonlinear Excitations in Biomolecules'' is to attempt to bridge the gap between the physicists and biologists communities which is mainly due to language and cultural barriers. The progress of nonlinear science in the last few decades which have shown that the combination of nonlinearity, which characterize most biological phenomena, and cooperative effects in a system having a large number of degrees of freedom, can give rise to coherent excitations with remarkable properties. New concepts, such as solitons nd nonlinear energy localisation have become familiar to physicists and applied mathematicians. It is thus tempting to make an analogy between these coherent excitations and the exceptional stability of some biological processes, such as for instance DNA transcription, which require the coordination of many events in the ever changing environment of a cell. Physicists are now invoking nonlinear excitations to describe and explain many bio-molecular processes while biologists often doubt that the seemingly infinite variety of phenomena that they are attempting to classify can be reduced to such simple concepts. A large part of the meeting is devoted to tutorial lectures rather than to latest research results. The book provides a pedagogical introduction to the two topics forming the backbone of the meeting: the theory of nonlinear excitations and solitons, and their application in biology; and the structure and function of biomolecules, as well as energy and charge transport in biophysics. In order to emphasize the link between physics and biology, the volume is not divided along these two topics but according to biological subjects. Each chapter starts with a short introduction attempting to help the reader to find his way among the contributions and point out the connection between them. 23 lectures over the 32 presented have been selected and refers to quantum properties of macro-molecules. (J.S.)

  1. CONNECTING THE VANISHING FLORA, FAUNA AND ITS RELATION TO THE INDIAN REMOVAL POLICY AS SEEN IN COOPERS THE LEATHERSTOCKING TALES

    Directory of Open Access Journals (Sweden)

    Ceisy Nita Wuntu

    2016-02-01

    Full Text Available This study aims at connecting the vanishing flora, fauna and its Relation to the Indian removal policy in Coopers The Leatherstocking Tales. This research applies an American Studies interdisciplinary principle supplemented by the myth and symbol theory proposed by Henry Nash Smith. Smith claimed the importance of imaginative works in revealing American culture. He declared that the historical, anthropological and cultural, sociological, and ecological data as covered in this research can be equipped by data from imaginative works. Hence, in this research, those data are presented integratedly in their context of past and present. In this research, in order to highlight environmental matters in Coopers The Leatherstocking Tales, the analysis covers the data above that are integrated with the data revealed in The Leatherstocking Tales as a whole by employing the concept of ecocriticism. The spirit of the immigrants to have a better life in the new world, stimulated by its rich, lush and beautiful circumstances, in fact, is not an aim of a sustainable life. The desire to improve their life is not enough without using and treating its environment wisely as well as facing it with the environmental conservation paradigm. The spirit of doing the exploitation is a consequence of western humanism value. The reason of coming to America to avoid the population density as well as the competition of life cannot be attained when the immigrants experience the same population density and harsh competition as in their old world and when the beautiful nature disappears, the forests become cities, the tranquility becomes noisy and crowded, and the people experience the uncomfortable life that many kinds of conflict can follow. It is not on the right path when they cannot maintain the grandeur of nature, because they are not directing their way to the right, sustainable way of life as alerted and meant by Cooper. Ecologically, the superabundance of the land when

  2. Oscillations in nonlinear systems

    CERN Document Server

    Hale, Jack K

    2015-01-01

    By focusing on ordinary differential equations that contain a small parameter, this concise graduate-level introduction to the theory of nonlinear oscillations provides a unified approach to obtaining periodic solutions to nonautonomous and autonomous differential equations. It also indicates key relationships with other related procedures and probes the consequences of the methods of averaging and integral manifolds.Part I of the text features introductory material, including discussions of matrices, linear systems of differential equations, and stability of solutions of nonlinear systems. Pa

  3. Nonlinearity in nanomechanical cantilevers

    DEFF Research Database (Denmark)

    Villanueva Torrijo, Luis Guillermo; Karabalin, R. B.; Matheny, M. H.

    2013-01-01

    Euler-Bernoulli beam theory is widely used to successfully predict the linear dynamics of micro-and nanocantilever beams. However, its capacity to characterize the nonlinear dynamics of these devices has not yet been rigorously assessed, despite its use in nanoelectromechanical systems developmen....... These findings underscore the delicate balance between inertial and geometric nonlinear effects in the fundamental mode, and strongly motivate further work to develop theories beyond the Euler-Bernoulli approximation. DOI: 10.1103/PhysRevB.87.024304...

  4. Coupled nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, J; Scott, A C

    1983-01-01

    Topics discussed include transitions in weakly coupled nonlinear oscillators, singularly perturbed delay-differential equations, and chaos in simple laser systems. Papers are presented on truncated Navier-Stokes equations in a two-dimensional torus, on frequency locking in Josephson point contacts, and on soliton excitations in Josephson tunnel junctions. Attention is also given to the nonlinear coupling of radiation pulses to absorbing anharmonic molecular media, to aspects of interrupted coarse-graining in stimulated excitation, and to a statistical analysis of long-term dynamic irregularity in an exactly soluble quantum mechanical model.

  5. Engineered nonlinear lattices

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Christiansen, Peter Leth; Torner, L.

    1999-01-01

    We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear...... discrete equation. The proposed structure therefore provides an experimental setting for exploring discrete effects in a controlled manner. In particular, we show propagation of breathers that are eventually trapped by discreteness. When the stripes are wide the beams evolve in a structure we term...

  6. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2012-01-01

    Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

  7. Nonlinear equilibrium in Tokamaks including convective terms and viscosity

    International Nuclear Information System (INIS)

    Martin, P.; Castro, E.; Puerta, J.

    2003-01-01

    MHD equilibrium in tokamaks becomes very complex, when the non-linear convective term and viscosity are included in the momentum equation. In order to simplify the analysis, each new term has been separated in type gradient terms and vorticity depending terms. For the special case in which the vorticity vanishes, an extended Grad-Shafranov type equation can be obtained. However now the magnetic surface is not isobars or current surfaces as in the usual Grad-Shafranov treatment. The non-linear convective terms introduces gradient of Bernoulli type kinetic terms . Montgomery and other authors have shown the importance of the viscosity terms in tokamaks [1,2], here the treatment is carried out for the equilibrium condition, including generalized tokamaks coordinates recently described [3], which simplify the equilibrium analysis. Calculation of the new isobar surfaces is difficult and some computation have been carried out elsewhere for some particular cases [3]. Here, our analysis is extended discussing how the toroidal current density, plasma pressure and toroidal field are modified across the midplane because of the new terms (convective and viscous). New calculations and computations are also presented. (Author)

  8. Nonlinear silicon photonics

    Science.gov (United States)

    Tsia, Kevin K.; Jalali, Bahram

    2010-05-01

    An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.

  9. Nonlinear Regression with R

    CERN Document Server

    Ritz, Christian; Parmigiani, Giovanni

    2009-01-01

    R is a rapidly evolving lingua franca of graphical display and statistical analysis of experiments from the applied sciences. This book provides a coherent treatment of nonlinear regression with R by means of examples from a diversity of applied sciences such as biology, chemistry, engineering, medicine and toxicology.

  10. Nonlinear silicon photonics

    Science.gov (United States)

    Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

    2017-09-01

    Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

  11. Generalized Nonlinear Yule Models

    Science.gov (United States)

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-11-01

    With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.

  12. Intramolecular and nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Davis, M.J. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.

  13. Balancing for nonlinear systems

    NARCIS (Netherlands)

    Scherpen, J.M.A.

    1993-01-01

    We present a method of balancing for nonlinear systems which is an extension of balancing for linear systems in the sense that it is based on the input and output energy of a system. It is a local result, but gives 'broader' results than we obtain by just linearizing the system. Furthermore, the

  14. Vanishing of T sub c and appearance of quantum paraelectricity in KD sub 2 PO sub 4 and KH sub 2 PO sub 4 under high pressure

    CERN Document Server

    Endo, S; Tokunaga, M

    2002-01-01

    The temperature dependences of the dielectric constants of the hydrogen-bond ferroelectrics KH sub 2 PO sub 4 (KDP) and KD sub 2 PO sub 4 (DKDP) were measured under high hydrostatic pressure. Their ferroelectric transition temperatures T sub c monotonically decreased with increasing pressure and the ferroelectric state vanished at p sub c : 1.7 GPa for KDP and 6.1 GPa for DKDP. On the other hand, the Curie constant remained finite at p sub c , which indicates that the ferroelectric phase transition at high pressure is of displacive type. At pressures around p sub c , quantum paraelectricity was observed in KDP and DKDP.

  15. Identification of nonlinear anelastic models

    International Nuclear Information System (INIS)

    Draganescu, G E; Bereteu, L; Ercuta, A

    2008-01-01

    A useful nonlinear identification technique applied to the anelastic and rheologic models is presented in this paper. First introduced by Feldman, the method is based on the Hilbert transform, and is currently used for identification of the nonlinear vibrations

  16. Nonlinear chaos control and synchronization

    NARCIS (Netherlands)

    Huijberts, H.J.C.; Nijmeijer, H.; Schöll, E.; Schuster, H.G.

    2007-01-01

    This chapter contains sections titled: Introduction Nonlinear Geometric Control Some Differential Geometric Concepts Nonlinear Controllability Chaos Control Through Feedback Linearization Chaos Control Through Input-Output Linearization Lyapunov Design Lyapunov Stability and Lyapunov's First Method

  17. Analytical and numerical investigation of nonlinear internal gravity waves

    Directory of Open Access Journals (Sweden)

    S. P. Kshevetskii

    2001-01-01

    Full Text Available The propagation of long, weakly nonlinear internal waves in a stratified gas is studied. Hydrodynamic equations for an ideal fluid with the perfect gas law describe the atmospheric gas behaviour. If we neglect the term Ͽ dw/dt (product of the density and vertical acceleration, we come to a so-called quasistatic model, while we name the full hydro-dynamic model as a nonquasistatic one. Both quasistatic and nonquasistatic models are used for wave simulation and the models are compared among themselves. It is shown that a smooth classical solution of a nonlinear quasistatic problem does not exist for all t because a gradient catastrophe of non-linear internal waves occurs. To overcome this difficulty, we search for the solution of the quasistatic problem in terms of a generalised function theory as a limit of special regularised equations containing some additional dissipation term when the dissipation factor vanishes. It is shown that such solutions of the quasistatic problem qualitatively differ from solutions of a nonquasistatic nature. It is explained by the fact that in a nonquasistatic model the vertical acceleration term plays the role of a regularizator with respect to a quasistatic model, while the solution qualitatively depends on the regularizator used. The numerical models are compared with some analytical results. Within the framework of the analytical model, any internal wave is described as a system of wave modes; each wave mode interacts with others due to equation non-linearity. In the principal order of a perturbation theory, each wave mode is described by some equation of a KdV type. The analytical model reveals that, in a nonquasistatic model, an internal wave should disintegrate into solitons. The time of wave disintegration into solitons, the scales and amount of solitons generated are important characteristics of the non-linear process; they are found with the help of analytical and numerical investigations. Satisfactory

  18. Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole

    2001-01-01

    We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...... the case of a power-law nonlinearity in detail. We discuss several scenarios of the instability-induced dynamics of the nonlinear impurity modes, including the mode decay or switching to a new stable state, and collapse at the impurity site....

  19. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2013-01-01

    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...... breathing of a single-cycle THz pulse in a semiconductor....

  20. FRF decoupling of nonlinear systems

    Science.gov (United States)

    Kalaycıoğlu, Taner; Özgüven, H. Nevzat

    2018-03-01

    Structural decoupling problem, i.e. predicting dynamic behavior of a particular substructure from the knowledge of the dynamics of the coupled structure and the other substructure, has been well investigated for three decades and led to several decoupling methods. In spite of the inherent nonlinearities in a structural system in various forms such as clearances, friction and nonlinear stiffness, all decoupling studies are for linear systems. In this study, decoupling problem for nonlinear systems is addressed for the first time. A method, named as FRF Decoupling Method for Nonlinear Systems (FDM-NS), is proposed for calculating FRFs of a substructure decoupled from a coupled nonlinear structure where nonlinearity can be modeled as a single nonlinear element. Depending on where nonlinear element is, i.e., either in the known or unknown subsystem, or at the connection point, the formulation differs. The method requires relative displacement information between two end points of the nonlinear element, in addition to point and transfer FRFs at some points of the known subsystem. However, it is not necessary to excite the system from the unknown subsystem even when the nonlinear element is in that subsystem. The validation of FDM-NS is demonstrated with two different case studies using nonlinear lumped parameter systems. Finally, a nonlinear experimental test structure is used in order to show the real-life application and accuracy of FDM-NS.

  1. Rogue waves in nonlinear science

    International Nuclear Information System (INIS)

    Yan Zhenya

    2012-01-01

    Rogue waves, as a special type of solitary waves, play an important role in nonlinear optics, Bose-Einstein condensates, ocean, atmosphere, and even finance. In this report, we mainly review on the history of the rogue wave phenomenon and recent development of rogue wave solutions in some nonlinear physical models arising in the fields of nonlinear science.

  2. H∞ Balancing for Nonlinear Systems

    NARCIS (Netherlands)

    Scherpen, Jacquelien M.A.

    1996-01-01

    In previously obtained balancing methods for nonlinear systems a past and a future energy function are used to bring the nonlinear system in balanced form. By considering a different pair of past and future energy functions that are related to the H∞ control problem for nonlinear systems we define

  3. [Association between homozygous c.318A>GT mutation in exon 2 of the EIF2B5 gene and the infantile form of vanishing white matter leukoencephalopathy].

    Science.gov (United States)

    Esmer, Carmen; Blanco Hernández, Gabriela; Saavedra Alanís, Víctor; Reyes Vaca, Jorge Guillermo; Bravo Oro, Antonio

    Vanishing white matter disease is one of the most frequent leukodystrophies in childhood with an autosomal recessive inheritance. A mutation in one of the genes encoding the five subunits of the eukaryotic initiation factor 2 (EIF2B5) is present in 90% of the cases. The diagnosis can be accomplished by the clinical and neuroradiological findings and molecular tests. We describe a thirteen-month-old male with previous normal neurodevelopment, who was hospitalized for vomiting, hyperthermia and irritability. On examination, cephalic perimeter and cranial pairs were normal. Hypotonia, increased muscle stretching reflexes, generalized white matter hypodensity on cranial tomography were found. Fifteen days after discharge, he suffered minor head trauma presenting drowsiness and focal seizures. Magnetic resonance showed generalized hypointensity of white matter. Vanishing white matter disease was suspected, and confirmed by sequencing of the EIF2B5 gene, revealing a homozygous c.318A> T mutation in exon 2. Subsequently, visual acuity was lost and cognitive and motor deterioration was evident. The patient died at six years of age due to severe pneumonia. This case contributes to the knowledge of the mutational spectrum present in Mexican patients and allows to extend the phenotype associated to this mutation. Copyright © 2017. Publicado por Masson Doyma México S.A.

  4. Nonlinear differential equations

    Energy Technology Data Exchange (ETDEWEB)

    Dresner, L.

    1988-01-01

    This report is the text of a graduate course on nonlinear differential equations given by the author at the University of Wisconsin-Madison during the summer of 1987. The topics covered are: direction fields of first-order differential equations; the Lie (group) theory of ordinary differential equations; similarity solutions of second-order partial differential equations; maximum principles and differential inequalities; monotone operators and iteration; complementary variational principles; and stability of numerical methods. The report should be of interest to graduate students, faculty, and practicing scientists and engineers. No prior knowledge is required beyond a good working knowledge of the calculus. The emphasis is on practical results. Most of the illustrative examples are taken from the fields of nonlinear diffusion, heat and mass transfer, applied superconductivity, and helium cryogenics.

  5. Nonlinear (Anharmonic Casimir Oscillator

    Directory of Open Access Journals (Sweden)

    Habibollah Razmi

    2011-01-01

    Full Text Available We want to study the dynamics of a simple linear harmonic micro spring which is under the influence of the quantum Casimir force/pressure and thus behaves as a (an nonlinear (anharmonic Casimir oscillator. Generally, the equation of motion of this nonlinear micromechanical Casimir oscillator has no exact solvable (analytical solution and the turning point(s of the system has (have no fixed position(s; however, for particular values of the stiffness of the micro spring and at appropriately well-chosen distance scales and conditions, there is (are approximately sinusoidal solution(s for the problem (the variable turning points are collected in a very small interval of positions. This, as a simple and elementary plan, may be useful in controlling the Casimir stiction problem in micromechanical devices.

  6. Limits to Nonlinear Inversion

    DEFF Research Database (Denmark)

    Mosegaard, Klaus

    2012-01-01

    For non-linear inverse problems, the mathematical structure of the mapping from model parameters to data is usually unknown or partly unknown. Absence of information about the mathematical structure of this function prevents us from presenting an analytical solution, so our solution depends on our......-heuristics are inefficient for large-scale, non-linear inverse problems, and that the 'no-free-lunch' theorem holds. We discuss typical objections to the relevance of this theorem. A consequence of the no-free-lunch theorem is that algorithms adapted to the mathematical structure of the problem perform more efficiently than...... pure meta-heuristics. We study problem-adapted inversion algorithms that exploit the knowledge of the smoothness of the misfit function of the problem. Optimal sampling strategies exist for such problems, but many of these problems remain hard. © 2012 Springer-Verlag....

  7. Nonlinear Photonics 2014: introduction.

    Science.gov (United States)

    Akhmediev, N; Kartashov, Yaroslav

    2015-01-12

    International Conference "Nonlinear Photonics-2014" took place in Barcelona, Spain on July 27-31, 2014. It was a part of the "Advanced Photonics Congress" which is becoming a traditional notable event in the world of photonics. The current focus issue of Optics Express contains contributions from the participants of the Conference and the Congress. The articles in this focus issue by no means represent the total number of the congress contributions (around 400). However, it demonstrates wide range of topics covered at the event. The next conference of this series is to be held in 2016 in Australia, which is the home of many researchers working in the field of photonics in general and nonlinear photonics in particular.

  8. Nonlinear data assimilation

    CERN Document Server

    Van Leeuwen, Peter Jan; Reich, Sebastian

    2015-01-01

    This book contains two review articles on nonlinear data assimilation that deal with closely related topics but were written and can be read independently. Both contributions focus on so-called particle filters. The first contribution by Jan van Leeuwen focuses on the potential of proposal densities. It discusses the issues with present-day particle filters and explorers new ideas for proposal densities to solve them, converging to particle filters that work well in systems of any dimension, closing the contribution with a high-dimensional example. The second contribution by Cheng and Reich discusses a unified framework for ensemble-transform particle filters. This allows one to bridge successful ensemble Kalman filters with fully nonlinear particle filters, and allows a proper introduction of localization in particle filters, which has been lacking up to now.

  9. Essentials of nonlinear optics

    CERN Document Server

    Murti, Y V G S

    2014-01-01

    Current literature on Nonlinear Optics varies widely in terms of content, style, and coverage of specific topics, relative emphasis of areas and the depth of treatment. While most of these books are excellent resources for the researchers, there is a strong need for books appropriate for presenting the subject at the undergraduate or postgraduate levels in Universities. The need for such a book to serve as a textbook at the level of the bachelors and masters courses was felt by the authors while teaching courses on nonlinear optics to students of both science and engineering during the past two decades. This book has emerged from an attempt to address the requirement of presenting the subject at college level. A one-semester course covering the essentials can effectively be designed based on this.

  10. Nonlinear differential equations

    International Nuclear Information System (INIS)

    Dresner, L.

    1988-01-01

    This report is the text of a graduate course on nonlinear differential equations given by the author at the University of Wisconsin-Madison during the summer of 1987. The topics covered are: direction fields of first-order differential equations; the Lie (group) theory of ordinary differential equations; similarity solutions of second-order partial differential equations; maximum principles and differential inequalities; monotone operators and iteration; complementary variational principles; and stability of numerical methods. The report should be of interest to graduate students, faculty, and practicing scientists and engineers. No prior knowledge is required beyond a good working knowledge of the calculus. The emphasis is on practical results. Most of the illustrative examples are taken from the fields of nonlinear diffusion, heat and mass transfer, applied superconductivity, and helium cryogenics

  11. The forced nonlinear Schroedinger equation

    International Nuclear Information System (INIS)

    Kaup, D.J.; Hansen, P.J.

    1985-01-01

    The nonlinear Schroedinger equation describes the behaviour of a radio frequency wave in the ionosphere near the reflexion point where nonlinear processes are important. A simple model of this phenomenon leads to the forced nonlinear Schroedinger equation in terms of a nonlinear boundary value problem. A WKB analysis of the time evolution equations for the nonlinear Schroedinger equation in the inverse scattering transform formalism gives a crude order of magnitude estimation of the qualitative behaviour of the solutions. This estimation is compared with the numerical solutions. (D.Gy.)

  12. Nonlinear fibre optics overview

    DEFF Research Database (Denmark)

    Travers, J. C.; Frosz, Michael Henoch; Dudley, J. M.

    2010-01-01

    The optical fiber based supercontinuum source has recently become a significant scientific and commercial success, with applications ranging from frequency comb production to advanced medical imaging. This one-of-a-kind book explains the theory of fiber supercontinuum broadening, describes......, provides a background to the associated nonlinear optical processes, treats the generation mechanisms from continuous wave to femtosecond pulse pump regimes and highlights the diverse applications. A full discussion of numerical methods and comprehensive computer code are also provided, enabling readers...

  13. Damped nonlinear Schrodinger equation

    International Nuclear Information System (INIS)

    Nicholson, D.R.; Goldman, M.V.

    1976-01-01

    High frequency electrostatic plasma oscillations described by the nonlinear Schrodinger equation in the presence of damping, collisional or Landau, are considered. At early times, Landau damping of an initial soliton profile results in a broader, but smaller amplitude soliton, while collisional damping reduces the soliton size everywhere; soliton speeds at early times are unchanged by either kind of damping. For collisional damping, soliton speeds are unchanged for all time

  14. Nonlinearity without superluminality

    International Nuclear Information System (INIS)

    Kent, Adrian

    2005-01-01

    Quantum theory is compatible with special relativity. In particular, though measurements on entangled systems are correlated in a way that cannot be reproduced by local hidden variables, they cannot be used for superluminal signaling. As Czachor, Gisin, and Polchinski pointed out, this is not generally true of general nonlinear modifications of the Schroedinger equation. Excluding superluminal signaling has thus been taken to rule out most nonlinear versions of quantum theory. The no-superluminal-signaling constraint has also been used for alternative derivations of the optimal fidelities attainable for imperfect quantum cloning and other operations. These results apply to theories satisfying the rule that their predictions for widely separated and slowly moving entangled systems can be approximated by nonrelativistic equations of motion with respect to a preferred time coordinate. This paper describes a natural way in which this rule might fail to hold. In particular, it is shown that quantum readout devices which display the values of localized pure states need not allow superluminal signaling, provided that the devices display the values of the states of entangled subsystems as defined in a nonstandard, although natural, way. It follows that any locally defined nonlinear evolution of pure states can be made consistent with Minkowski causality

  15. Direct test of a nonlinear constitutive equation for simple turbulent shear flows using DNS data

    Science.gov (United States)

    Schmitt, François G.

    2007-10-01

    Several nonlinear constitutive equations have been proposed to overcome the limitations of the linear eddy-viscosity models to describe complex turbulent flows. These nonlinear equations have often been compared to experimental data through the outputs of numerical models. Here we perform a priori analysis of nonlinear eddy-viscosity models using direct numerical simulation (DNS) of simple shear flows. In this paper, the constitutive equation is directly checked using a tensor projection which involves several invariants of the flow. This provides a 3 terms development which is exact for 2D flows, and a best approximation for 3D flows. We provide the quadratic nonlinear constitutive equation for the near-wall region of simple shear flows using DNS data, and estimate their coefficients. We show that these coefficients have several common properties for the different simple shear flow databases considered. We also show that in the central region of pipe flows, where the shear rate is very small, the coefficients of the constitutive equation diverge, indicating the failure of this representation for vanishing shears.

  16. Nonlinear robust hierarchical control for nonlinear uncertain systems

    Directory of Open Access Journals (Sweden)

    Leonessa Alexander

    1999-01-01

    Full Text Available A nonlinear robust control-system design framework predicated on a hierarchical switching controller architecture parameterized over a set of moving nominal system equilibria is developed. Specifically, using equilibria-dependent Lyapunov functions, a hierarchical nonlinear robust control strategy is developed that robustly stabilizes a given nonlinear system over a prescribed range of system uncertainty by robustly stabilizing a collection of nonlinear controlled uncertain subsystems. The robust switching nonlinear controller architecture is designed based on a generalized (lower semicontinuous Lyapunov function obtained by minimizing a potential function over a given switching set induced by the parameterized nominal system equilibria. The proposed framework robustly stabilizes a compact positively invariant set of a given nonlinear uncertain dynamical system with structured parametric uncertainty. Finally, the efficacy of the proposed approach is demonstrated on a jet engine propulsion control problem with uncertain pressure-flow map data.

  17. Discrete nonlinear Schrodinger equations with arbitrarily high-order nonlinearities

    DEFF Research Database (Denmark)

    Khare, A.; Rasmussen, Kim Ø; Salerno, M.

    2006-01-01

    -Ladik equation. As a common property, these equations possess three kinds of exact analytical stationary solutions for which the Peierls-Nabarro barrier is zero. Several properties of these solutions, including stability, discrete breathers, and moving solutions, are investigated.......A class of discrete nonlinear Schrodinger equations with arbitrarily high-order nonlinearities is introduced. These equations are derived from the same Hamiltonian using different Poisson brackets and include as particular cases the saturable discrete nonlinear Schrodinger equation and the Ablowitz...

  18. Non-linear osmosis

    Science.gov (United States)

    Diamond, Jared M.

    1966-01-01

    1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall-bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes. 2. As in many other tissues, water flow was found to vary with gradient in a markedly non-linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow. 3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186-825 m-osM. 4. The resistance to water flow was the same when the gall-bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities. 5. Of the theories advanced to explain non-linear osmosis in other tissues, flow-induced membrane deformations, unstirred layers, asymmetrical series-membrane effects, and non-osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non-linear osmosis in rabbit gall-bladder is due to a decrease in water permeability with increasing osmolarity. 6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered. PMID:5945254

  19. Nonlinear diffusion equations

    CERN Document Server

    Wu Zhuo Qun; Li Hui Lai; Zhao Jun Ning

    2001-01-01

    Nonlinear diffusion equations, an important class of parabolic equations, come from a variety of diffusion phenomena which appear widely in nature. They are suggested as mathematical models of physical problems in many fields, such as filtration, phase transition, biochemistry and dynamics of biological groups. In many cases, the equations possess degeneracy or singularity. The appearance of degeneracy or singularity makes the study more involved and challenging. Many new ideas and methods have been developed to overcome the special difficulties caused by the degeneracy and singularity, which

  20. Methods of nonlinear analysis

    CERN Document Server

    Bellman, Richard Ernest

    1970-01-01

    In this book, we study theoretical and practical aspects of computing methods for mathematical modelling of nonlinear systems. A number of computing techniques are considered, such as methods of operator approximation with any given accuracy; operator interpolation techniques including a non-Lagrange interpolation; methods of system representation subject to constraints associated with concepts of causality, memory and stationarity; methods of system representation with an accuracy that is the best within a given class of models; methods of covariance matrix estimation;methods for low-rank mat

  1. Nonlinear optimal control theory

    CERN Document Server

    Berkovitz, Leonard David

    2012-01-01

    Nonlinear Optimal Control Theory presents a deep, wide-ranging introduction to the mathematical theory of the optimal control of processes governed by ordinary differential equations and certain types of differential equations with memory. Many examples illustrate the mathematical issues that need to be addressed when using optimal control techniques in diverse areas. Drawing on classroom-tested material from Purdue University and North Carolina State University, the book gives a unified account of bounded state problems governed by ordinary, integrodifferential, and delay systems. It also dis

  2. Topics in Nonlinear Dynamics

    DEFF Research Database (Denmark)

    Mosekilde, Erik

    Through a significant number of detailed and realistic examples this book illustrates how the insights gained over the past couple of decades in the fields of nonlinear dynamics and chaos theory can be applied in practice. Aomng the topics considered are microbiological reaction systems, ecological...... food-web systems, nephron pressure and flow regulation, pulsatile secretion of hormones, thermostatically controlled radiator systems, post-stall maneuvering of aircrafts, transfer electron devices for microwave generation, economic long waves, human decision making behavior, and pattern formation...... in chemical reaction-diffusion systems....

  3. Nonlinear dynamics in psychology

    Directory of Open Access Journals (Sweden)

    Stephen J. Guastello

    2001-01-01

    Full Text Available This article provides a survey of the applications of nonlinear dynamical systems theory to substantive problems encountered in the full scope of psychological science. Applications are organized into three topical areas – cognitive science, social and organizational psychology, and personality and clinical psychology. Both theoretical and empirical studies are considered with an emphasis on works that capture the broadest scope of issues that are of substantive interest to psychological theory. A budding literature on the implications of NDS principles in professional practice is reported also.

  4. Nonlinear Hamiltonian systems

    DEFF Research Database (Denmark)

    Jørgensen, Michael Finn

    1995-01-01

    It is generally very difficult to solve nonlinear systems, and such systems often possess chaotic solutions. In the rare event that a system is completely solvable, it is said to integrable. Such systems never have chaotic solutions. Using the Inverse Scattering Transform Method (ISTM) two...... particular configurations of the Discrete Self-Trapping (DST) system are shown to be completely solvable. One of these systems includes the Toda lattice in a certain limit. An explicit integration is carried through for this Near-Toda lattice. The Near-Toda lattice is then generalized to include singular...

  5. Nonlinear surface electromagnetic phenomena

    CERN Document Server

    Ponath, H-E

    1991-01-01

    In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are

  6. Oscillators from nonlinear realizations

    Science.gov (United States)

    Kozyrev, N.; Krivonos, S.

    2018-02-01

    We construct the systems of the harmonic and Pais-Uhlenbeck oscillators, which are invariant with respect to arbitrary noncompact Lie algebras. The equations of motion of these systems can be obtained with the help of the formalism of nonlinear realizations. We prove that it is always possible to choose time and the fields within this formalism in such a way that the equations of motion become linear and, therefore, reduce to ones of ordinary harmonic and Pais-Uhlenbeck oscillators. The first-order actions, that produce these equations, can also be provided. As particular examples of this construction, we discuss the so(2, 3) and G 2(2) algebras.

  7. Global Analysis of Nonlinear Dynamics

    CERN Document Server

    Luo, Albert

    2012-01-01

    Global Analysis of Nonlinear Dynamics collects chapters on recent developments in global analysis of non-linear dynamical systems with a particular emphasis on cell mapping methods developed by Professor C.S. Hsu of the University of California, Berkeley. This collection of contributions prepared by a diverse group of internationally recognized researchers is intended to stimulate interests in global analysis of complex and high-dimensional nonlinear dynamical systems, whose global properties are largely unexplored at this time. This book also: Presents recent developments in global analysis of non-linear dynamical systems Provides in-depth considerations and extensions of cell mapping methods Adopts an inclusive style accessible to non-specialists and graduate students Global Analysis of Nonlinear Dynamics is an ideal reference for the community of nonlinear dynamics in different disciplines including engineering, applied mathematics, meteorology, life science, computational science, and medicine.  

  8. Nonlinearity management in higher dimensions

    International Nuclear Information System (INIS)

    Kevrekidis, P G; Pelinovsky, D E; Stefanov, A

    2006-01-01

    In the present paper, we revisit nonlinearity management of the time-periodic nonlinear Schroedinger equation and the related averaging procedure. By means of rigorous estimates, we show that the averaged nonlinear Schroedinger equation does not blow up in the higher dimensional case so long as the corresponding solution remains smooth. In particular, we show that the H 1 norm remains bounded, in contrast with the usual blow-up mechanism for the focusing Schroedinger equation. This conclusion agrees with earlier works in the case of strong nonlinearity management but contradicts those in the case of weak nonlinearity management. The apparent discrepancy is explained by the divergence of the averaging procedure in the limit of weak nonlinearity management

  9. Collapse of nonlinear Langmuir waves

    International Nuclear Information System (INIS)

    Malkin, V.M.

    1986-01-01

    The dispersion of sufficiently intensive Langmuir waves is determined by intrinsic (electron) nonlinearity. During Langmuir collapse the wave energy density required for the appearance of electron nonlinearity is attained, generally speaking, prior to the development of dissipative processes. Up to now, the effect of electron nonlinearity on the collapse dynamics and spectrum of strong Langmuir turbulence ( which may be very appreciable ) has not been studied extensively because of the difficulty of describing nonlinear Langmuir waves. In the present paper the positive determinacy of the electron nonlinear hamiltonian is proven, the increment of modulation instability of a nonlinear Langmuir wave cluster localized in a cavity is calculated, and the universal law of their collapse is found

  10. Leucoencefalopatia megalencefálica com substância branca evanescente e cistos subcorticais Megalencephalic leukoencephalopathy with vanishing white matter and cystic formation

    Directory of Open Access Journals (Sweden)

    Hélio Araújo Oliveira

    2004-12-01

    Full Text Available Apresentamos três casos de leucoencefalopatia megalencefálica com substancia branca evanescente e cistos subcorticais, diagnosticados através da ressonância nuclear magnética.Os casos estudados apresentam quadro clinico e radiológico de acordo com os critérios diagnósticos estabelecidos na descrição inicial desta enfermidade. São discutidos os aspectos clínicos e neuroradiológicos.We present three cases of megalencephalic leukoencephalopathy with vanishing white matter and cystic formation in both temporal lobes, diagnosed through magnetic resonance imaging. All the cases presented clinical and radiological aspects according to the diagnostic criteria that were established in the initial description of the syndrome. Clinical and radiological aspects are discussed.

  11. Emerging quasi-0D states at vanishing total entropy of the 1D hard sphere system: A coarse-grained similarity to the car parking problem

    Science.gov (United States)

    Frusawa, Hiroshi

    2014-05-01

    A coarse-grained system of one-dimensional (1D) hard spheres (HSs) is created using the Delaunay tessellation, which enables one to define the quasi-0D state. It is found from comparing the quasi-0D and 1D free energy densities that a frozen state due to the emergence of quasi-0D HSs is thermodynamically more favorable than fluidity with a large-scale heterogeneity above crossover volume fraction of ϕc=e/(1+e)=0.731⋯ , at which the total entropy of the 1D state vanishes. The Delaunay-based lattice mapping further provides a similarity between the dense HS system above ϕc and the jamming limit in the car parking problem.

  12. Emerging quasi-0D states at vanishing total entropy of the 1D hard sphere system: A coarse-grained similarity to the car parking problem

    International Nuclear Information System (INIS)

    Frusawa, Hiroshi

    2014-01-01

    A coarse-grained system of one-dimensional (1D) hard spheres (HSs) is created using the Delaunay tessellation, which enables one to define the quasi-0D state. It is found from comparing the quasi-0D and 1D free energy densities that a frozen state due to the emergence of quasi-0D HSs is thermodynamically more favorable than fluidity with a large-scale heterogeneity above crossover volume fraction of ϕ c =e/(1+e)=0.731⋯ , at which the total entropy of the 1D state vanishes. The Delaunay-based lattice mapping further provides a similarity between the dense HS system above ϕ c and the jamming limit in the car parking problem.

  13. Applications of nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2008-01-01

    * The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The bo

  14. Recent topics in nonlinear PDE

    International Nuclear Information System (INIS)

    Mimura, Masayasu; Nishida, Takaaki

    1984-01-01

    The meeting on the subject of nonlinear partial differential equations was held at Hiroshima University in February, 1983. Leading and active mathematicians were invited to talk on their current research interests in nonlinear pdes occuring in the areas of fluid dynamics, free boundary problems, population dynamics and mathematical physics. This volume contains the theory of nonlinear pdes and the related topics which have been recently developed in Japan. (Auth.)

  15. An optimal approach to active damping of nonlinear vibrations in composite plates using piezoelectric patches

    International Nuclear Information System (INIS)

    Saviz, M R

    2015-01-01

    In this paper a nonlinear approach to studying the vibration characteristic of laminated composite plate with surface-bonded piezoelectric layer/patch is formulated, based on the Green Lagrange type of strain–displacements relations, by incorporating higher-order terms arising from nonlinear relations of kinematics into mathematical formulations. The equations of motion are obtained through the energy method, based on Lagrange equations and by using higher-order shear deformation theories with von Karman–type nonlinearities, so that transverse shear strains vanish at the top and bottom surfaces of the plate. An isoparametric finite element model is provided to model the nonlinear dynamics of the smart plate with piezoelectric layer/ patch. Different boundary conditions are investigated. Optimal locations of piezoelectric patches are found using a genetic algorithm to maximize spatial controllability/observability and considering the effect of residual modes to reduce spillover effect. Active attenuation of vibration of laminated composite plate is achieved through an optimal control law with inequality constraint, which is related to the maximum and minimum values of allowable voltage in the piezoelectric elements. To keep the voltages of actuator pairs in an allowable limit, the Pontryagin’s minimum principle is implemented in a system with multi-inequality constraint of control inputs. The results are compared with similar ones, proving the accuracy of the model especially for the structures undergoing large deformations. The convergence is studied and nonlinear frequencies are obtained for different thickness ratios. The structural coupling between plate and piezoelectric actuators is analyzed. Some examples with new features are presented, indicating that the piezo-patches significantly improve the damping characteristics of the plate for suppressing the geometrically nonlinear transient vibrations. (paper)

  16. Perspectives of nonlinear dynamics

    International Nuclear Information System (INIS)

    Jackson, E.A.

    1985-03-01

    Four lectures were given weekly in October and November, 1984, and some of the ideas presented here will be of use in the future. First, a brief survey of the historical development of nonlinear dynamics since about 1890 was given, and then, a few topics were discussed in detail. The objective was to introduce some of many concepts and methods which are presently used for describing nonlinear dynamics. The symbiotic relationship between sciences of all types and mathematics, two main categories of the models describing nature, the method for describing the dynamics of a system, the idea of control parameters and topological dimension, the asymptotic properties of dynamics, abstract dynamics, the concept of embedding, singular perturbation theory, strange attractor, Fermi-Pasta-Ulam phenomena, an example of computer heuristics, the idea of elementary catastrophe theory and so on were explained. The logistic map is the simplest introduction to complex dynamics. The complicated dynamics is referred to as strange attractors. Two-dimensional maps are the highest dimensional maps commonly studied. These were discussed in detail. (Kako, I.)

  17. Nonlinearities in Behavioral Macroeconomics.

    Science.gov (United States)

    Gomes, Orlando

    2017-07-01

    This article undertakes a journey across the literature on behavioral macroeconomics, with attention concentrated on the nonlinearities that the behavioral approach typically suggests or implies. The emphasis is placed on thinking the macro economy as a living organism, composed of many interacting parts, each one having a will of its own, which is in sharp contrast with the mechanism of the orthodox view (well represented by the neoclassical or new Keynesian dynamic stochastic general equilibrium - DSGE - model). The paper advocates that a thorough understanding of individual behavior in collective contexts is the only possible avenue to further explore macroeconomic phenomena and the often observed 'anomalies' that the benchmark DSGE macro framework is unable to explain or justify. After a reflection on the role of behavioral traits as a fundamental component of a new way of thinking the economy, the article proceeds with a debate on some of the most relevant frameworks in the literature that somehow link macro behavior and nonlinearities; covered subjects include macro models with disequilibrium rules, agent-based models that highlight interaction and complexity, evolutionary switching frameworks, and inattention based decision problems. These subjects have, as a fundamental point in common, the use of behavioral elements to transform existing interpretations of the economic reality, making it more evident how irregular fluctuations emerge and unfold on the aggregate.

  18. The role of collective self-gravity in the nonlinear evolution of viscous overstability in Saturn's rings.

    Science.gov (United States)

    Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki

    2017-06-01

    We investigate the influence of collective self-gravity forces on the nonlinear evolution of the viscous overstability in Saturn's dense rings. Local N-body simulations, incorporating vertical and radial collective self-gravity are performed. Vertical self-gravity is mimicked through an increased frequency of vertical oscillations, while radial self-gravity is approximated by solving the Poisson equation for a thin disk in Fourier space. Direct particle-particle forces are omitted, while the magnitude of radial self gravity is controlled by assigning a variable surface mass density to the system's homogeneous ground state. We compare our simulations with large-scale isothermal and non-isothermal hydrodynamic model calculations, including radial self-gravity and employing transport coefficients derived in Salo et al. (2001). We concentrate on optical depths τ=1.5-2, appropriate to model Saturn's dense rings. Our isothermal and non isothermal hydrodynamic results in the limit of vanishing self-gravity compare very well with the studies of Latter&Ogilvie (2010) and Rein&latter (2013), respectively.With non-vanishing radial self-gravity we find that the wavelengths of saturated overstable wave trains are located in close vicinity of the local minimum of the nonlinear dispersion relation for a particular surface density. Good agreement is found between non-isothermal hydrodynamics and N-body simulations for disks with strong radial self-gravity, while the largest deviations occur for a weak but non-vanishing self-gravity.The resulting saturation wavelengths of the viscous overstability for moderate and strong radial self-gravity (λ~ 200-300m) agree reasonably well with the length scale of periodic micro structure in Saturn's inner A and B ring, as found by Cassini.

  19. Nonlinear Waves in Complex Systems

    DEFF Research Database (Denmark)

    2007-01-01

    The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations, it is the ......The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations...

  20. Problems in nonlinear resistive MHD

    International Nuclear Information System (INIS)

    Turnbull, A.D.; Strait, E.J.; La Haye, R.J.; Chu, M.S.; Miller, R.L.

    1998-01-01

    Two experimentally relevant problems can relatively easily be tackled by nonlinear MHD codes. Both problems require plasma rotation in addition to the nonlinear mode coupling and full geometry already incorporated into the codes, but no additional physics seems to be crucial. These problems discussed here are: (1) nonlinear coupling and interaction of multiple MHD modes near the B limit and (2) nonlinear coupling of the m/n = 1/1 sawtooth mode with higher n gongs and development of seed islands outside q = 1

  1. Influence of nanoscale temperature rises on photoacoustic generation: Discrimination between optical absorbers based on thermal nonlinearity at high frequency.

    Science.gov (United States)

    Simandoux, Olivier; Prost, Amaury; Gateau, Jérôme; Bossy, Emmanuel

    2015-03-01

    In this work, we experimentally investigate thermal-based nonlinear photoacoustic generation as a mean to discriminate between different types of absorbing particles. The photoacoustic generation from solutions of dye molecules and gold nanospheres (same optical densities) was detected using a high frequency ultrasound transducer (20 MHz). Photoacoustic emission was observed with gold nanospheres at low fluence for an equilibrium temperature around 4 °C, where the linear photoacoustic effect in water vanishes, highlighting the nonlinear emission from the solution of nanospheres. The photoacoustic amplitude was also studied as a function of the equilibrium temperature from 2 °C to 20 °C. While the photoacoustic amplitude from the dye molecules vanished around 4 °C, the photoacoustic amplitude from the gold nanospheres remained significant over the whole temperature range. Our preliminary results suggest that in the context of high frequency photoacoustic imaging, nanoparticles may be discriminated from molecular absorbers based on nanoscale temperature rises.

  2. Nonlinear Response of Strong Nonlinear System Arisen in Polymer Cushion

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available A dynamic model is proposed for a polymer foam-based nonlinear cushioning system. An accurate analytical solution for the nonlinear free vibration of the system is derived by applying He's variational iteration method, and conditions for resonance are obtained, which should be avoided in the cushioning design.

  3. Perspectives on Nonlinear Filtering

    KAUST Repository

    Law, Kody

    2015-01-01

    The solution to the problem of nonlinear filtering may be given either as an estimate of the signal (and ideally some measure of concentration), or as a full posterior distribution. Similarly, one may evaluate the fidelity of the filter either by its ability to track the signal or its proximity to the posterior filtering distribution. Hence, the field enjoys a lively symbiosis between probability and control theory, and there are plenty of applications which benefit from algorithmic advances, from signal processing, to econometrics, to large-scale ocean, atmosphere, and climate modeling. This talk will survey some recent theoretical results involving accurate signal tracking with noise-free (degenerate) dynamics in high-dimensions (infinite, in principle, but say d between 103 and 108 , depending on the size of your application and your computer), and high-fidelity approximations of the filtering distribution in low dimensions (say d between 1 and several 10s).

  4. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    Despite the general recession in the global economy and the collapse of the optical telecommunication market, research within specialty fibers is thriving. This is, more than anything else, due to the technology transition from standard all-glass fibers to photonic crystal fibers, which, instead....... The freedom to design the dispersion profile of the fibers is much larger and it is possible to create fibers, which support only a single spatial mode, regardless of wavelength. In comparison, the standard dispersion-shifted fibers are limited by a much lower index-contrast between the core and the cladding...... in 1996, and are today on their way to become the dominating technology within the specialty fiber field. Whether they will replace the standard fiber in the more traditional areas like telecommunication transmission, is not yet clear, but the nonlinear photonic crystal fibers are here to stay....

  5. Nonlinear estimation and classification

    CERN Document Server

    Hansen, Mark; Holmes, Christopher; Mallick, Bani; Yu, Bin

    2003-01-01

    Researchers in many disciplines face the formidable task of analyzing massive amounts of high-dimensional and highly-structured data This is due in part to recent advances in data collection and computing technologies As a result, fundamental statistical research is being undertaken in a variety of different fields Driven by the complexity of these new problems, and fueled by the explosion of available computer power, highly adaptive, non-linear procedures are now essential components of modern "data analysis," a term that we liberally interpret to include speech and pattern recognition, classification, data compression and signal processing The development of new, flexible methods combines advances from many sources, including approximation theory, numerical analysis, machine learning, signal processing and statistics The proposed workshop intends to bring together eminent experts from these fields in order to exchange ideas and forge directions for the future

  6. Nonlinear Water Waves

    CERN Document Server

    2016-01-01

    This volume brings together four lecture courses on modern aspects of water waves. The intention, through the lectures, is to present quite a range of mathematical ideas, primarily to show what is possible and what, currently, is of particular interest. Water waves of large amplitude can only be fully understood in terms of nonlinear effects, linear theory being not adequate for their description. Taking advantage of insights from physical observation, experimental evidence and numerical simulations, classical and modern mathematical approaches can be used to gain insight into their dynamics. The book presents several avenues and offers a wide range of material of current interest. Due to the interdisciplinary nature of the subject, the book should be of interest to mathematicians (pure and applied), physicists and engineers. The lectures provide a useful source for those who want to begin to investigate how mathematics can be used to improve our understanding of water wave phenomena. In addition, some of the...

  7. Perspectives on Nonlinear Filtering

    KAUST Repository

    Law, Kody

    2015-01-07

    The solution to the problem of nonlinear filtering may be given either as an estimate of the signal (and ideally some measure of concentration), or as a full posterior distribution. Similarly, one may evaluate the fidelity of the filter either by its ability to track the signal or its proximity to the posterior filtering distribution. Hence, the field enjoys a lively symbiosis between probability and control theory, and there are plenty of applications which benefit from algorithmic advances, from signal processing, to econometrics, to large-scale ocean, atmosphere, and climate modeling. This talk will survey some recent theoretical results involving accurate signal tracking with noise-free (degenerate) dynamics in high-dimensions (infinite, in principle, but say d between 103 and 108 , depending on the size of your application and your computer), and high-fidelity approximations of the filtering distribution in low dimensions (say d between 1 and several 10s).

  8. Homogeneous and isotropic cosmologies with nonlinear electromagnetic radiation

    International Nuclear Information System (INIS)

    Vollick, Dan N.

    2008-01-01

    In this paper I examine cosmological models that contain a stochastic background of nonlinear electromagnetic radiation. I show that for Born-Infeld electrodynamics the equation of state parameter, w=P/ρ, remains close to 1/3 throughout the evolution of the universe if E 2 =B 2 in the late universe to a high degree of accuracy. Theories with electromagnetic Lagrangians of the form L=-(1/4)F 2 +αF 4 have recently been studied in magnetic universes, where the electric field vanishes. It was shown that the F 4 term can produce a bounce in the early universe, avoiding an initial singularity. Here I show that the inclusion of an electric field, with E 2 ≅B 2 in the late universe, eliminates the bounce and the universe begins with an initial singularity. I also examine theories with Lagrangians of the form L=-(1/4)F 2 -μ 8 /F 2 , which have been shown to produce a period of late time accelerated expansion in magnetic universes. I show that, if an electric field is introduced, the accelerated phase will only occur if E 2 2 .

  9. Wave transmission in nonlinear lattices

    International Nuclear Information System (INIS)

    Hennig, D.; Tsironis, G.P.

    1999-01-01

    The interplay of nonlinearity with lattice discreteness leads to phenomena and propagation properties quite distinct from those appearing in continuous nonlinear systems. For a large variety of condensed matter and optics applications the continuous wave approximation is not appropriate. In the present review we discuss wave transmission properties in one dimensional nonlinear lattices. Our paradigmatic equations are discrete nonlinear Schroedinger equations and their study is done through a dynamical systems approach. We focus on stationary wave properties and utilize well known results from the theory of dynamical systems to investigate various aspects of wave transmission and wave localization. We analyze in detail the more general dynamical system corresponding to the equation that interpolates between the non-integrable discrete nonlinear Schroedinger equation and the integrable Albowitz-Ladik equation. We utilize this analysis in a nonlinear Kronig-Penney model and investigate transmission and band modification properties. We discuss the modifications that are effected through an electric field and the nonlinear Wannier-Stark localization effects that are induced. Several applications are described, such as polarons in one dimensional lattices, semiconductor superlattices and one dimensional nonlinear photonic band gap systems. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Solving Nonlinear Coupled Differential Equations

    Science.gov (United States)

    Mitchell, L.; David, J.

    1986-01-01

    Harmonic balance method developed to obtain approximate steady-state solutions for nonlinear coupled ordinary differential equations. Method usable with transfer matrices commonly used to analyze shaft systems. Solution to nonlinear equation, with periodic forcing function represented as sum of series similar to Fourier series but with form of terms suggested by equation itself.

  11. Nonlinear Elasticity of Doped Semiconductors

    Science.gov (United States)

    2017-02-01

    AFRL-RY-WP-TR-2016-0206 NONLINEAR ELASTICITY OF DOPED SEMICONDUCTORS Mark Dykman and Kirill Moskovtsev Michigan State University...2016 4. TITLE AND SUBTITLE NONLINEAR ELASTICITY OF DOPED SEMICONDUCTORS 5a. CONTRACT NUMBER FA8650-16-1-7600 5b. GRANT NUMBER 5c. PROGRAM...vibration amplitude. 15. SUBJECT TERMS semiconductors , microresonators, microelectromechanical 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  12. Nonlinear evolution of MHD instabilities

    International Nuclear Information System (INIS)

    Bateman, G.; Hicks, H.R.; Wooten, J.W.; Dory, R.A.

    1975-01-01

    A 3-D nonlinear MHD computer code was used to study the time evolution of internal instabilities. Velocity vortex cells are observed to persist into the nonlinear evolution. Pressure and density profiles convect around these cells for a weak localized instability, or convect into the wall for a strong instability. (U.S.)

  13. Nonlinear theory of elastic shells

    International Nuclear Information System (INIS)

    Costa Junior, J.A.

    1979-08-01

    Nonlinear theory of elastic shells is developed which incorporates both geometric and physical nonlinearities and which does not make use of the well known Love-Kirchhoff hypothesis. The resulting equations are formulated in tensorial notation and are reduced to the ones of common use when simplifying assumptions encountered in the especific litterature are taken. (Author) [pt

  14. Balancing for Unstable Nonlinear Systems

    NARCIS (Netherlands)

    Scherpen, J.M.A.

    1993-01-01

    A previously obtained method of balancing for stable nonlinear systems is extended to unstable nonlinear systems. The similarity invariants obtained by the concept of LQG balancing for an unstable linear system can also be obtained by considering a past and future energy function of the system. By

  15. Nonlinear evolution of magnetic islands in a two fluid torus

    International Nuclear Information System (INIS)

    Sugiyama, L.E.; Park, W.

    1996-01-01

    A numerical model MH3D-T for the two fluid description of macroscopic evolution in a full three dimensional torus has been developed. Based on the perturbative drift ordering, generalized to arbitrary perturbation size, the model follows the full temperature evolution, including the thermal equilibration along the magnetic field. It contains the diamagnetic drifts, ion gyroviscous stress tensor, and the Hall term in Ohm's law. Electron inertia is neglected. The numerical model solves the same equations in a torus and in several simplified configurations. It has been benchmarked against the diamagnetic ω* i stabilization of the resistive m = 1, n = 1 reconnecting mode in a cylinder. The nonlinear evolution of resistive magnetic islands with m,n ≠ 1,1 in a cylinder is found to agree with previous analytic and reduced-torus results, which show that the diamagnetic rotation vanishes early in the island evolution and the saturated island size is determined by the same external driving factor Δ' as in MHD. The two fluid evolution in a full torus, however, differs from that in a cylinder and from the resistive MHD evolution. The poloidal rotation velocity undergoes a degree of poloidal momentum damping in the torus, even without neoclassical effects. The two fluid magnetic island grows faster, nonlinearly, than the resistive MHD island, and also couples different toroidal harmonics more effectively. Plasma compressibility and processes operating along the magnetic field play a much more important role than in MHD or in simple geometry. The two fluid model contains all the important neoclassical fluid effects except for the b circ ∇ circ Π parallelj viscous force terms. The addition of these terms is in progress

  16. Nonlinear hyperbolic waves in multidimensions

    CERN Document Server

    Prasad, Phoolan

    2001-01-01

    The propagation of curved, nonlinear wavefronts and shock fronts are very complex phenomena. Since the 1993 publication of his work Propagation of a Curved Shock and Nonlinear Ray Theory, author Phoolan Prasad and his research group have made significant advances in the underlying theory of these phenomena. This volume presents their results and provides a self-contained account and gradual development of mathematical methods for studying successive positions of these fronts.Nonlinear Hyperbolic Waves in Multidimensions includes all introductory material on nonlinear hyperbolic waves and the theory of shock waves. The author derives the ray theory for a nonlinear wavefront, discusses kink phenomena, and develops a new theory for plane and curved shock propagation. He also derives a full set of conservation laws for a front propagating in two space dimensions, and uses these laws to obtain successive positions of a front with kinks. The treatment includes examples of the theory applied to converging wavefronts...

  17. Cubication of conservative nonlinear oscillators

    International Nuclear Information System (INIS)

    Belendez, Augusto; Alvarez, Mariela L; Fernandez, Elena; Pascual, Inmaculada

    2009-01-01

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.

  18. Nonlinear Ritz approximation for Fredholm functionals

    Directory of Open Access Journals (Sweden)

    Mudhir A. Abdul Hussain

    2015-11-01

    Full Text Available In this article we use the modify Lyapunov-Schmidt reduction to find nonlinear Ritz approximation for a Fredholm functional. This functional corresponds to a nonlinear Fredholm operator defined by a nonlinear fourth-order differential equation.

  19. Breatherlike impurity modes in discrete nonlinear lattices

    DEFF Research Database (Denmark)

    Hennig, D.; Rasmussen, Kim; Tsironis, G. P.

    1995-01-01

    We investigate the properties of a disordered generalized discrete nonlinear Schrodinger equation, containing both diagonal and nondiagonal nonlinear terms. The equation models a Linear host lattice doped with nonlinear impurities. We find different types of impurity states that form itinerant...

  20. Identification of nonlinear coupling in wave turbulence at the surface of water

    Science.gov (United States)

    Campagne, Antoine; Hassaini, Roumaissa; Redor, Ivan; Aubourg, Quentin; Sommeria, Joël; Mordant, Nicolas

    2017-11-01

    The Weak Turbulence Theory is a theory, in the limit of vanishing nonlinearity, that derive analytically statistical features of wave turbulence. The stationary spectrum for the surface elevation in the case of gravity waves, is predicted to E(k) k - 5 / 2 . This spectral exponent -5/2 remains elusive in all experiments. in which the measured exponent is systematically lower than the prediction. Furthermore in the experiments the weaker the nonlinearity the further the spectral exponent is from the prediction. In order to investigate the reason for this observation we developed an experiment in the CORIOLIS facility in Grenoble. It is a 13m-diameter circular pool filled with water with a 70 cm depth. We generate wave turbulence by using two wedge wavemakers. Surface elevation measurements are performed by a stereoscopic optical technique and by capacitive probes. The nonlinear coupling at work in this system are analyzed by computing 3- and 4-wave correlations of the Fourier wave amplitudes in frequency. Theory predicts that coupling should occur through 4-wave resonant interaction. In our data, strong 3-wave correlations are observed in addition to the 4-wave correlation. Most our observations are consistent with field observation in the Black Sea (Leckler et al. 2015). This project has received funding from the European Research Council (ERC, Grant Agreement No 647018-WATU).

  1. Grain size effects on stability of nonlinear vibration with nanocrystalline NiTi shape memory alloy

    Science.gov (United States)

    Xia, Minglu; Sun, Qingping

    2017-10-01

    Grain size effects on stability of thermomechanical responses for a nonlinear torsional vibration system with nanocrystalline superelastic NiTi bar are investigated in the frequency and amplitude domains. NiTi bars with average grain size from 10 nm to 100 nm are fabricated through cold-rolling and subsequent annealing. Thermomechanical responses of the NiTi bar as a softening nonlinear damping spring in the torsional vibration system are obtained by synchronised acquisition of rotational angle and temperature under external sinusoidal excitation. It is shown that nonlinearity and damping capacity of the NiTi bar decrease as average grain size of the material is reduced below 100 nm. Therefore jump phenomena of thermomechanical responses become less significant or even vanish and the vibration system becomes more stable. The work in this paper provides a solid experimental base for manipulating the undesired jump phenomena of thermomechanical responses and stabilising the mechanical vibration system through grain refinement of NiTi SMA.

  2. Spatial solitons in nonlinear photonic crystals

    DEFF Research Database (Denmark)

    Corney, Joel Frederick; Bang, Ole

    2000-01-01

    We study solitons in one-dimensional quadratic nonlinear photonic crystals with periodic linear and nonlinear susceptibilities. We show that such crystals support stable bright and dark solitons, even when the effective quadratic nonlinearity is zero.......We study solitons in one-dimensional quadratic nonlinear photonic crystals with periodic linear and nonlinear susceptibilities. We show that such crystals support stable bright and dark solitons, even when the effective quadratic nonlinearity is zero....

  3. LDRD report nonlinear model reduction

    Energy Technology Data Exchange (ETDEWEB)

    Segalman, D.; Heinstein, M.

    1997-09-01

    The very general problem of model reduction of nonlinear systems was made tractable by focusing on the very large subclass consisting of linear subsystems connected by nonlinear interfaces. Such problems constitute a large part of the nonlinear structural problems encountered in addressing the Sandia missions. A synthesis approach to this class of problems was developed consisting of: detailed modeling of the interface mechanics; collapsing the interface simulation results into simple nonlinear interface models; constructing system models by assembling model approximations of the linear subsystems and the nonlinear interface models. These system models, though nonlinear, would have very few degrees of freedom. A paradigm problem, that of machine tool vibration, was selected for application of the reduction approach outlined above. Research results achieved along the way as well as the overall modeling of a specific machine tool have been very encouraging. In order to confirm the interface models resulting from simulation, it was necessary to develop techniques to deduce interface mechanics from experimental data collected from the overall nonlinear structure. A program to develop such techniques was also pursued with good success.

  4. Nonlinear time heteronymous damping in nonlinear parametric planetary systems

    Czech Academy of Sciences Publication Activity Database

    Hortel, Milan; Škuderová, Alena

    2014-01-01

    Roč. 225, č. 7 (2014), s. 2059-2073 ISSN 0001-5970 Institutional support: RVO:61388998 Keywords : nonlinear dynamics * planetary systems * heteronymous damping Subject RIV: JT - Propulsion, Motors ; Fuels Impact factor: 1.465, year: 2014

  5. Design with Nonlinear Constraints

    KAUST Repository

    Tang, Chengcheng

    2015-12-10

    Most modern industrial and architectural designs need to satisfy the requirements of their targeted performance and respect the limitations of available fabrication technologies. At the same time, they should reflect the artistic considerations and personal taste of the designers, which cannot be simply formulated as optimization goals with single best solutions. This thesis aims at a general, flexible yet e cient computational framework for interactive creation, exploration and discovery of serviceable, constructible, and stylish designs. By formulating nonlinear engineering considerations as linear or quadratic expressions by introducing auxiliary variables, the constrained space could be e ciently accessed by the proposed algorithm Guided Projection, with the guidance of aesthetic formulations. The approach is introduced through applications in different scenarios, its effectiveness is demonstrated by examples that were difficult or even impossible to be computationally designed before. The first application is the design of meshes under both geometric and static constraints, including self-supporting polyhedral meshes that are not height fields. Then, with a formulation bridging mesh based and spline based representations, the application is extended to developable surfaces including origami with curved creases. Finally, general approaches to extend hard constraints and soft energies are discussed, followed by a concluding remark outlooking possible future studies.

  6. Nonlinear functional analysis

    CERN Document Server

    Deimling, Klaus

    1985-01-01

    topics. However, only a modest preliminary knowledge is needed. In the first chapter, where we introduce an important topological concept, the so-called topological degree for continuous maps from subsets ofRn into Rn, you need not know anything about functional analysis. Starting with Chapter 2, where infinite dimensions first appear, one should be familiar with the essential step of consider­ ing a sequence or a function of some sort as a point in the corresponding vector space of all such sequences or functions, whenever this abstraction is worthwhile. One should also work out the things which are proved in § 7 and accept certain basic principles of linear functional analysis quoted there for easier references, until they are applied in later chapters. In other words, even the 'completely linear' sections which we have included for your convenience serve only as a vehicle for progress in nonlinearity. Another point that makes the text introductory is the use of an essentially uniform mathematical languag...

  7. Scalable Nonlinear Compact Schemes

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Debojyoti [Argonne National Lab. (ANL), Argonne, IL (United States); Constantinescu, Emil M. [Univ. of Chicago, IL (United States); Brown, Jed [Univ. of Colorado, Boulder, CO (United States)

    2014-04-01

    In this work, we focus on compact schemes resulting in tridiagonal systems of equations, specifically the fifth-order CRWENO scheme. We propose a scalable implementation of the nonlinear compact schemes by implementing a parallel tridiagonal solver based on the partitioning/substructuring approach. We use an iterative solver for the reduced system of equations; however, we solve this system to machine zero accuracy to ensure that no parallelization errors are introduced. It is possible to achieve machine-zero convergence with few iterations because of the diagonal dominance of the system. The number of iterations is specified a priori instead of a norm-based exit criterion, and collective communications are avoided. The overall algorithm thus involves only point-to-point communication between neighboring processors. Our implementation of the tridiagonal solver differs from and avoids the drawbacks of past efforts in the following ways: it introduces no parallelization-related approximations (multiprocessor solutions are exactly identical to uniprocessor ones), it involves minimal communication, the mathematical complexity is similar to that of the Thomas algorithm on a single processor, and it does not require any communication and computation scheduling.

  8. Acoustic-gravity nonlinear structures

    Directory of Open Access Journals (Sweden)

    D. Jovanović

    2002-01-01

    Full Text Available A catalogue of nonlinear vortex structures associated with acoustic-gravity perturbations in the Earth's atmosphere is presented. Besides the previously known Kelvin-Stewart cat's eyes, dipolar and tripolar structures, new solutions having the form of a row of counter-rotating vortices, and several weakly two-dimensional vortex chains are given. The existence conditions for these nonlinear structures are discussed with respect to the presence of inhomogeneities of the shear flows. The mode-coupling mechanism for the nonlinear generation of shear flows in the presence of linearly unstable acoustic-gravity waves, possibly also leading to intermittency and chaos, is presented.

  9. Nonlinear Dynamic Phenomena in Mechanics

    CERN Document Server

    Warminski, Jerzy; Cartmell, Matthew P

    2012-01-01

    Nonlinear phenomena should play a crucial role in the design and control of engineering systems and structures as they can drastically change the prevailing dynamical responses. This book covers theoretical and applications-based problems of nonlinear dynamics concerned with both discrete and continuous systems of interest in civil and mechanical engineering. They include pendulum-like systems, slender footbridges, shape memory alloys, sagged elastic cables and non-smooth problems. Pendulums can be used as a dynamic absorber mounted in high buildings, bridges or chimneys. Geometrical nonlinear

  10. Non-linear optical materials

    CERN Document Server

    Saravanan, R

    2018-01-01

    Non-linear optical materials have widespread and promising applications, but the efforts to understand the local structure, electron density distribution and bonding is still lacking. The present work explores the structural details, the electron density distribution and the local bond length distribution of some non-linear optical materials. It also gives estimation of the optical band gap, the particle size, crystallite size, and the elemental composition from UV-Visible analysis, SEM, XRD and EDS of some non-linear optical materials respectively.

  11. Nonlinear modulation of ionization waves

    International Nuclear Information System (INIS)

    Bekki, Naoaki

    1981-01-01

    In order to investigate the nonlinear characteristics of ionization waves (moving-striations) in the positive column of glow discharge, a nonlinear modulation of ionization waves in the region of the Pupp critical current is analysed by means of the reductive perturbation method. The modulation of ionization waves is described by a nonlinear Schroedinger type equation. The coefficients of the equation are evaluated using the data of the low pressure Argon-discharge, and the simple solutions (plane wave and envelope soliton type solutions) are presented. Under a certain condition an envelope soliton is propagated through the positive column. (author)

  12. Single-shot measurement of nonlinear absorption and nonlinear refraction.

    Science.gov (United States)

    Jayabalan, J; Singh, Asha; Oak, Shrikant M

    2006-06-01

    A single-shot method for measurement of nonlinear optical absorption and refraction is described and analyzed. A spatial intensity variation of an elliptical Gaussian beam in conjugation with an array detector is the key element of this method. The advantages of this single-shot technique were demonstrated by measuring the two-photon absorption and free-carrier absorption in GaAs as well as the nonlinear refractive index of CS2 using a modified optical Kerr setup.

  13. Infantile onset Vanishing White Matter disease associated with a novel EIF2B5 variant, remarkably long life span, severe epilepsy, and hypopituitarism.

    Science.gov (United States)

    Woody, April L; Hsieh, David T; McIver, Harkirtin K; Thomas, Linda P; Rohena, Luis

    2015-04-01

    Vanishing White Matter disease (VWM) is an inherited progressive leukoencephalopathy caused by mutations in the genes EIF2B1-5, which encode for the 5 subunits of the eukaryotic initiation factor 2B (eIF2B), a regulator of protein synthesis. VWM typically presents with acute neurological decline following febrile infections or minor head trauma, and subsequent progressive neurological and cognitive regression. There is a varied clinical spectrum of VWM, with earlier onset associated with more severe phenotypes. Brain magnetic resonance imaging is usually diagnostic with diffusely abnormal white matter, progressing over time to cystic degeneration. We are reporting on a patient with infantile onset VWM associated with three heterozygous missense variants in EIF2B5, including a novel missense variant on exon 6 of EIF2B5 (D262N), as well as an interstitial duplication at 7q21.12. In addition, our case is unusual because of a severe epilepsy course, a novel clinical finding of hypopituitarism manifested by hypothyroidism and adrenal insufficiency, and a prolonged life span with current age of survival of 4 years and 11 months. © 2015 Wiley Periodicals, Inc.

  14. Nonlinear optics principles and applications

    CERN Document Server

    Li, Chunfei

    2017-01-01

    This book reflects the latest advances in nonlinear optics. Besides the simple, strict mathematical deduction, it also discusses the experimental verification and possible future applications, such as the all-optical switches. It consistently uses the practical unit system throughout. It employs simple physical images, such as "light waves" and "photons" to systematically explain the main principles of nonlinear optical effects. It uses the first-order nonlinear wave equation in frequency domain under the condition of “slowly varying amplitude approximation" and the classical model of the interaction between the light and electric dipole. At the same time, it also uses the rate equations based on the energy-level transition of particle systems excited by photons and the energy and momentum conservation principles to explain the nonlinear optical phenomenon. The book is intended for researchers, engineers and graduate students in the field of the optics, optoelectronics, fiber communication, information tech...

  15. Nonlinear Dynamics in Spear Wigglers

    International Nuclear Information System (INIS)

    2002-01-01

    BL11, the most recently installed wiggler in the SPEAR storage ring at SSRL, produces a large nonlinear perturbation of the electron beam dynamics, which was not directly evident in the integrated magnetic field measurements. Measurements of tune shifts with betatron oscillation amplitude and with closed orbit shifts were used to characterize the nonlinear fields of the SPEAR insertion devices (IDs). Because of the narrow pole width in BL11, the nonlinear fields seen along the wiggling electron trajectory are dramatically different than the flip coil measurements made along a straight line. This difference explains the tune shift measurements and the observed degradation in dynamic aperture. Corrector magnets to cancel the BL11 nonlinear fields are presently under construction

  16. Device Applications of Nonlinear Dynamics

    CERN Document Server

    Baglio, Salvatore

    2006-01-01

    This edited book is devoted specifically to the applications of complex nonlinear dynamic phenomena to real systems and device applications. While in the past decades there has been significant progress in the theory of nonlinear phenomena under an assortment of system boundary conditions and preparations, there exist comparatively few devices that actually take this rich behavior into account. "Device Applications of Nonlinear Dynamics" applies and exploits this knowledge to make devices which operate more efficiently and cheaply, while affording the promise of much better performance. Given the current explosion of ideas in areas as diverse as molecular motors, nonlinear filtering theory, noise-enhanced propagation, stochastic resonance and networked systems, the time is right to integrate the progress of complex systems research into real devices.

  17. Nonlinear programming analysis and methods

    CERN Document Server

    Avriel, Mordecai

    2012-01-01

    This text provides an excellent bridge between principal theories and concepts and their practical implementation. Topics include convex programming, duality, generalized convexity, analysis of selected nonlinear programs, techniques for numerical solutions, and unconstrained optimization methods.

  18. q-Deformed nonlinear maps

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 64; Issue 3 ... Keywords. Nonlinear dynamics; logistic map; -deformation; Tsallis statistics. ... As a specific example, a -deformation procedure is applied to the logistic map. Compared ...

  19. Born-Infeld Nonlinear Electrodynamics

    International Nuclear Information System (INIS)

    Bialynicki-Birula, I.

    1999-01-01

    This is only a summary of a lecture delivered at the Infeld Centennial Meeting. In the lecture the history of the Born-Infeld nonlinear electrodynamics was presented and some general features of the theory were discussed. (author)

  20. Nonlinear compression of optical solitons

    Indian Academy of Sciences (India)

    linear pulse propagation is the nonlinear Schrödinger (NLS) equation [1]. There are ... Optical pulse compression finds important applications in optical fibres. The pulse com ..... to thank CSIR, New Delhi for financial support in the form of SRF.

  1. Nonlinear transformations of random processes

    CERN Document Server

    Deutsch, Ralph

    2017-01-01

    This concise treatment of nonlinear noise techniques encountered in system applications is suitable for advanced undergraduates and graduate students. It is also a valuable reference for systems analysts and communication engineers. 1962 edition.

  2. Extreme Nonlinear Optics An Introduction

    CERN Document Server

    Wegener, Martin

    2005-01-01

    Following the birth of the laser in 1960, the field of "nonlinear optics" rapidly emerged. Today, laser intensities and pulse durations are readily available, for which the concepts and approximations of traditional nonlinear optics no longer apply. In this regime of "extreme nonlinear optics," a large variety of novel and unusual effects arise, for example frequency doubling in inversion symmetric materials or high-harmonic generation in gases, which can lead to attosecond electromagnetic pulses or pulse trains. Other examples of "extreme nonlinear optics" cover diverse areas such as solid-state physics, atomic physics, relativistic free electrons in a vacuum and even the vacuum itself. This book starts with an introduction to the field based primarily on extensions of two famous textbook examples, namely the Lorentz oscillator model and the Drude model. Here the level of sophistication should be accessible to any undergraduate physics student. Many graphical illustrations and examples are given. The followi...

  3. Nonlinear dynamics: Challenges and perspectives

    Indian Academy of Sciences (India)

    fields such as economics, social dynamics and so on [6–10]. These nonlinear ..... developing all-optical computers in homogeneous bulk media such as pho- ... suggestions have been given to develop effective chaos-based cryptographic.

  4. Nonlinear Optics: Principles and Applications

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Tidemand-Lichtenberg, Peter

    of applications, Nonlinear Optics: Principles and Applications effectively bridges physics and mathematics with relevant applied material for real-world use. The book progresses naturally from fundamental aspects to illustrative examples, and presents a strong theoretical foundation that equips the reader...... and matter, this text focuses on the physical understanding of nonlinear optics, and explores optical material response functions in the time and frequency domain....

  5. Dynamics of nonlinear feedback control

    OpenAIRE

    Snippe, H.P.; Hateren, J.H. van

    2007-01-01

    Feedback control in neural systems is ubiquitous. Here we study the mathematics of nonlinear feedback control. We compare models in which the input is multiplied by a dynamic gain (multiplicative control) with models in which the input is divided by a dynamic attenuation (divisive control). The gain signal (resp. the attenuation signal) is obtained through a concatenation of an instantaneous nonlinearity and a linear low-pass filter operating on the output of the feedback loop. For input step...

  6. On nonlinear periodic drift waves

    International Nuclear Information System (INIS)

    Kauschke, U.; Schlueter, H.

    1990-09-01

    Nonlinear periodic drift waves are investigated on the basis of a simple perturbation scheme for both the amplitude and inverse frequency. The coefficients for the generation of the forced harmonics are derived, a nonlinear dispersion relation is suggested and a criterion for the onset of the modulational instability is obtained. The results are compared with the ones obtained with the help of a standard KBM-treatment. Moreover cnoidal drift waves are suggested and compared to an experimental observation. (orig.)

  7. Competitive nonlinear pricing and bundling

    OpenAIRE

    Armstrong, Mark; Vickers, John

    2006-01-01

    We examine the impact of multiproduct nonlinear pricing on profit, consumer surplus and welfare in a duopoly. When consumers buy all their products from one firm (the one-stop shopping model), nonlinear pricing leads to higher profit and welfare, but often lower consumer surplus, than linear pricing. By contrast, in a unit-demand model where consumers may buy one product from one firm and another product from another firm, bundling generally acts to reduce profit and welfare and to boost cons...

  8. Captivate the customer or vanish

    International Nuclear Information System (INIS)

    Regis, J.

    1994-01-01

    Throughout its expansion program in the 1960s and its energy efficiency programs in the 1970s and 1980s, Hydro-Quebec had a satisfactory proportion of satisfied customers. However, at the end of the 1980s, the utility's customer satisfaction rating slipped below 50% for the first time. Hydro-Quebec's first response was to re-establish transmission system reliability. Service interruptions per customer were reduced from 10 h/y in 1989 to just over 4 h in 1993. Starting in 1990, the utility devised a strategy aimed at fully integrated quality management, with customer service as the top priority. A series of performance commitments was adopted which pinpointed 27 specific targets, each linked to a specific activity; of those targets, 16 are directly related to customer service. A training plan was developed which makes the customer the focus of every action taken by a Hydro-Quebec employee, and office hours have been reorganized in response to constantly evolving customer needs. A courtesy call strategy has been adopted to anticipate customer expectations before they are expressed. Highly personalized and accurately targeted informational tools have been developed for each customer category and a toll-free energy efficiency hotline has been established. Energy efficiency publications are distributed to business and residential customers. Satisfaction with Hydro-Quebec activities rose from 77% in 1992 to 93% in 1993, and credibility in energy efficiency rose from 73% to 85%. A new project being investigated is an electronic superhighway with a variety of customer applications including home automation, load and meter telecontrol, telebilling, and direct payment

  9. Nonlinear optics principles and applications

    CERN Document Server

    Rottwitt, Karsten

    2014-01-01

    IntroductionReview of linear opticsInduced polarizationHarmonic oscillator modelLocal field correctionsEstimated nonlinear responseSummaryTime-domain material responseThe polarization time-response functionThe Born-Oppenheimer approximationRaman scattering response function of silicaSummaryMaterial response in the frequency domain, susceptibility tensorsThe susceptibility tensorThe induced polarization in the frequency domainSum of monochromatic fieldsThe prefactor to the induced polarizationThird-order polarization in the Born-Oppenheimer approximation in the frequency domainKramers-Kronig relationsSummarySymmetries in nonlinear opticsSpatial symmetriesSecond-order materialsThird-order nonlinear materialsCyclic coordinate-systemContracted notation for second-order susceptibility tensorsSummaryThe nonlinear wave equationMono and quasi-monochromatic beamsPlane waves - the transverse problemWaveguidesVectorial approachNonlinear birefringenceSummarySecond-order nonlinear effectsGeneral theoryCoupled wave theoryP...

  10. Modeling nonlinearities in MEMS oscillators.

    Science.gov (United States)

    Agrawal, Deepak K; Woodhouse, Jim; Seshia, Ashwin A

    2013-08-01

    We present a mathematical model of a microelectromechanical system (MEMS) oscillator that integrates the nonlinearities of the MEMS resonator and the oscillator circuitry in a single numerical modeling environment. This is achieved by transforming the conventional nonlinear mechanical model into the electrical domain while simultaneously considering the prominent nonlinearities of the resonator. The proposed nonlinear electrical model is validated by comparing the simulated amplitude-frequency response with measurements on an open-loop electrically addressed flexural silicon MEMS resonator driven to large motional amplitudes. Next, the essential nonlinearities in the oscillator circuit are investigated and a mathematical model of a MEMS oscillator is proposed that integrates the nonlinearities of the resonator. The concept is illustrated for MEMS transimpedance-amplifier- based square-wave and sine-wave oscillators. Closed-form expressions of steady-state output power and output frequency are derived for both oscillator models and compared with experimental and simulation results, with a good match in the predicted trends in all three cases.

  11. BOOK REVIEW: Nonlinear Magnetohydrodynamics

    Science.gov (United States)

    Shafranov, V.

    1998-08-01

    Nonlinear magnetohydrodynamics by Dieter Biskamp is a thorough introduction to the physics of the most impressive non-linear phenomena that occur in conducting magnetoplasmas. The basic systems, in which non-trivial dynamic processes are observed, accompanied by changes of geometry of the magnetic field and the effects of energy transformation (magnetic energy into kinetic energy or the opposite effect in magnetic dynamos), are the plasma magnetic confinement systems for nuclear fusion and space plasmas, mainly the solar plasma. A significant number of the examples of the dynamic processes considered are taken from laboratory plasmas, for which an experimental check of the theory is possible. Therefore, though the book is intended for researchers and students interested in both laboratory, including nuclear fusion, and astrophysical plasmas, it is most probably closer to the first category of reader. In the Introduction the author notes that unlike the hydrodynamics of non-conducting fluids, where the phenomena caused by rapid fluid motions are the most interesting, for plasmas in a strong magnetic field the quasi-static configurations inside which the local dynamic processes occur are often the most important. Therefore, the reader will also find in this book rather traditional material on the theory of plasma equilibrium and stability in magnetic fields. In addition, it is notable that, as opposed to a linear theory, the non-linear theory, as a rule, cannot give quite definite explanations or predictions of phenomena, and consequently there are in the book many results obtained by consideration of numerical models with the use of supercomputers. The treatment of non-linear dynamics is preceded by Chapters 2 to 4, in which the basics of MHD theory are presented with an emphasis on the role of integral invariants of the magnetic helicity type, a derivation of the reduced MHD equations is given, together with examples of the exact solutions of the equilibrium

  12. Nonlinear transport of dynamic system phase space

    International Nuclear Information System (INIS)

    Xie Xi; Xia Jiawen

    1993-01-01

    The inverse transform of any order solution of the differential equation of general nonlinear dynamic systems is derived, realizing theoretically the nonlinear transport for the phase space of nonlinear dynamic systems. The result is applicable to general nonlinear dynamic systems, with the transport of accelerator beam phase space as a typical example

  13. A reliable treatment for nonlinear Schroedinger equations

    International Nuclear Information System (INIS)

    Khani, F.; Hamedi-Nezhad, S.; Molabahrami, A.

    2007-01-01

    Exp-function method is used to find a unified solution of nonlinear wave equation. Nonlinear Schroedinger equations with cubic and power law nonlinearity are selected to illustrate the effectiveness and simplicity of the method. It is shown that the Exp-function method, with the help of symbolic computation, provides a powerful mathematical tool for solving nonlinear equation

  14. Identification of Nonlinear Dynamic Systems Possessing Some Non-linearities

    Directory of Open Access Journals (Sweden)

    Y. N. Pavlov

    2015-01-01

    Full Text Available The subject of this work is the problem of identification of nonlinear dynamic systems based on the experimental data obtained by applying test signals to the system. The goal is to determinate coefficients of differential equations of systems by experimental frequency hodographs and separate similar, but different, in essence, forces: dissipative forces with the square of the first derivative in the motion equations and dissipative force from the action of dry friction. There was a proposal to use the harmonic linearization method to approximate each of the nonlinearity of "quadratic friction" and "dry friction" by linear friction with the appropriate harmonic linearization coefficient.Assume that a frequency transfer function of the identified system has a known form. Assume as well that there are disturbances while obtaining frequency characteristics of the realworld system. As a result, the points of experimentally obtained hodograph move randomly. Searching for solution of the identification problem was in the hodograph class, specified by the system model, which has the form of the frequency transfer function the same as the form of the frequency transfer function of the system identified. Minimizing a proximity criterion (measure of the experimentally obtained system hodograph and the system hodograph model for all the experimental points described and previously published by one of the authors allowed searching for the unknown coefficients of the frequenc ransfer function of the system model. The paper shows the possibility to identify a nonlinear dynamic system with multiple nonlinearities, obtained on the experimental samples of the frequency system hodograph. The proposed algorithm allows to select the nonlinearity of the type "quadratic friction" and "dry friction", i.e. also in the case where the nonlinearity is dependent on the same dynamic parameter, in particular, on the derivative of the system output value. For the dynamic

  15. Final report. [Nonlinear magnetohydrodynamics

    International Nuclear Information System (INIS)

    Montgomery, D.C.

    1998-01-01

    This is a final report on the research activities carried out under the above grant at Dartmouth. During the period considered, the grant was identified as being for nonlinear magnetohydrodynamics, considered as the most tractable theoretical framework in which the plasma problems associated with magnetic confinement of fusion plasmas could be studied. During the first part of the grant's lifetime, the author was associated with Los Alamos National Laboratory as a consultant and the work was motivated by the reversed-field pinch. Later, when that program was killed at Los Alamos, the problems became ones that could be motivated by their relation to tokamaks. Throughout the work, the interest was always on questions that were as fundamental as possible, compatible with those motivations. The intent was always to contribute to plasma physics as a science, as well as to the understanding of mission-oriented confined fusion plasmas. Twelve Ph.D. theses were supervised during this period and a comparable number of postdoctoral research associates were temporarily supported. Many of these have gone on to distinguished careers, though few have done so in the context of the controlled fusion program. Their work was a combination of theory and numerical computation, in gradually less and less idealized settings, moving from rectangular periodic boundary conditions in two dimensions, through periodic straight cylinders and eventually, before the grant was withdrawn, to toroids, with a gradually more prominent role for electrical and mechanical boundary conditions. The author never had access to a situation where he could initiate experiments and relate directly to the laboratory data he wanted. Computers were the laboratory. Most of the work was reported in referred publications in the open literature, copies of which were transmitted one by one to DOE at the time they appeared. The Appendix to this report is a bibliography of published work which was carried out under the

  16. Complex motions and chaos in nonlinear systems

    CERN Document Server

    Machado, José; Zhang, Jiazhong

    2016-01-01

    This book brings together 10 chapters on a new stream of research examining complex phenomena in nonlinear systems—including engineering, physics, and social science. Complex Motions and Chaos in Nonlinear Systems provides readers a particular vantage of the nature and nonlinear phenomena in nonlinear dynamics that can develop the corresponding mathematical theory and apply nonlinear design to practical engineering as well as the study of other complex phenomena including those investigated within social science.

  17. Vanishing testes syndrome-related osteoporosis and high cardio-metabolic risk in an adult male with long term untreated hypergonadotropic hypogonadism.

    Science.gov (United States)

    Carsote, Mara; Capatina, Cristina; Valea, Ana; Dumitrascu, Anda

    2016-02-01

    The male hypogonadism-related bone mass loss is often under diagnosed. Peak bone mass is severely affected if the hypogonadism occurs during puberty and is left untreated. We present an interesting; almost bizarre case of a male with non-functional testes early during childhood and undiagnosed and untreated hypogonadism until his fifth decade of life. Forty six year male is referred for goitre, complaining of back pain. Phenotype suggested intersexuality: gynoid proportions, micropenis, no palpable testes into the scrotum, no facial or truncal hair. His medical history had been unremarkable until the previous year when primary hypothyroidism was diagnosed and levothyroxine replacement was initiated. Later, he was diagnosed with ischemic heart disease, with inaugural unstable angina. On admission, the testosterone was 0.2 ng/mL (normal: 1.7-7.8 ng/mL), FSH markedly increased (56 mUI/mL), with normal adrenal axis, and TSH (under thyroxine replacement). High bone turnover markers, and blood cholesterol, and impaired glucose tolerance were diagnosed. The testes were not present in the scrotum. Abdominal computed tomography suggested bilateral masses of 1.6 cm diameter within the abdominal fat that were removed but no gonadal tissue was confirmed histopathologically. Vanishing testes syndrome was confirmed. The central DXA showed lumbar bone mineral density of 0.905 g/cm2, Z-score of -2.9SD. The spine profile X-Ray revealed multiple thoracic vertebral fractures. Alendronate therapy together with vitamin D and calcium supplements and trans-dermal testosterone were started. Four decades of hypogonadism associate increased cardiac risk, as well as decreased bone mass and high fracture risk.

  18. Cascaded nonlinearities for ultrafast nonlinear optical science and applications

    DEFF Research Database (Denmark)

    Bache, Morten

    the cascading nonlinearity is investigated in detail, especially with focus on femtosecond energetic laser pulses being subjected to this nonlinear response. Analytical, numerical and experimental results are used to understand the cascading interaction and applications are demonstrated. The defocusing soliton...... observations with analogies in fiber optics are observed numerically and experimentally, including soliton self-compression, soliton-induced resonant radiation, supercontinuum generation, optical wavebreaking and shock-front formation. All this happens despite no waveguide being present, thanks...... is of particular interest here, since it is quite unique and provides the solution to a number of standing challenges in the ultrafast nonlinear optics community. It solves the problem of catastrophic focusing and formation of a filaments in bulk glasses, which even under controlled circumstances is limited...

  19. Input saturation in nonlinear multivariable processes resolved by nonlinear decoupling

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1995-04-01

    Full Text Available A new method is presented for the resolution of the problem of input saturation in nonlinear multivariable process control by means of elementary nonlinear decoupling (END. Input saturation can have serious consequences particularly in multivariable control because it may lead to very undesirable system behaviour and quite often system instability. Many authors have searched for systematic techniques for designing multivariable control systems in which saturation may occur in any of the control variables (inputs, manipulated variables. No generally accepted method seems to have been presented so far which gives a solution in closed form. The method of elementary nonlinear decoupling (END can be applied directly to the case of saturation control variables by deriving as many control strategies as there are combinations of saturating control variables. The method is demonstrated by the multivariable control of a simulated Fluidized Catalytic Cracker (FCC with very convincing results.

  20. Nonlinear analysis of pupillary dynamics.

    Science.gov (United States)

    Onorati, Francesco; Mainardi, Luca Tommaso; Sirca, Fabiola; Russo, Vincenzo; Barbieri, Riccardo

    2016-02-01

    Pupil size reflects autonomic response to different environmental and behavioral stimuli, and its dynamics have been linked to other autonomic correlates such as cardiac and respiratory rhythms. The aim of this study is to assess the nonlinear characteristics of pupil size of 25 normal subjects who participated in a psychophysiological experimental protocol with four experimental conditions, namely “baseline”, “anger”, “joy”, and “sadness”. Nonlinear measures, such as sample entropy, correlation dimension, and largest Lyapunov exponent, were computed on reconstructed signals of spontaneous fluctuations of pupil dilation. Nonparametric statistical tests were performed on surrogate data to verify that the nonlinear measures are an intrinsic characteristic of the signals. We then developed and applied a piecewise linear regression model to detrended fluctuation analysis (DFA). Two joinpoints and three scaling intervals were identified: slope α0, at slow time scales, represents a persistent nonstationary long-range correlation, whereas α1 and α2, at middle and fast time scales, respectively, represent long-range power-law correlations, similarly to DFA applied to heart rate variability signals. Of the computed complexity measures, α0 showed statistically significant differences among experimental conditions (pnonlinear dynamics, (b) three well-defined and distinct long-memory processes exist at different time scales, and (c) autonomic stimulation is partially reflected in nonlinear dynamics. (c) autonomic stimulation is partially reflected in nonlinear dynamics.

  1. Introduction to nonlinear dispersive equations

    CERN Document Server

    Linares, Felipe

    2015-01-01

    This textbook introduces the well-posedness theory for initial-value problems of nonlinear, dispersive partial differential equations, with special focus on two key models, the Korteweg–de Vries equation and the nonlinear Schrödinger equation. A concise and self-contained treatment of background material (the Fourier transform, interpolation theory, Sobolev spaces, and the linear Schrödinger equation) prepares the reader to understand the main topics covered: the initial-value problem for the nonlinear Schrödinger equation and the generalized Korteweg–de Vries equation, properties of their solutions, and a survey of general classes of nonlinear dispersive equations of physical and mathematical significance. Each chapter ends with an expert account of recent developments and open problems, as well as exercises. The final chapter gives a detailed exposition of local well-posedness for the nonlinear Schrödinger equation, taking the reader to the forefront of recent research. The second edition of Introdu...

  2. Nonlinear dynamics in biological systems

    CERN Document Server

    Carballido-Landeira, Jorge

    2016-01-01

    This book presents recent research results relating to applications of nonlinear dynamics, focusing specifically on four topics of wide interest: heart dynamics, DNA/RNA, cell mobility, and proteins. The book derives from the First BCAM Workshop on Nonlinear Dynamics in Biological Systems, held in June 2014 at the Basque Center of Applied Mathematics (BCAM). At this international meeting, researchers from different but complementary backgrounds, including molecular dynamics, physical chemistry, bio-informatics and biophysics, presented their most recent results and discussed the future direction of their studies using theoretical, mathematical modeling and experimental approaches. Such was the level of interest stimulated that the decision was taken to produce this publication, with the organizers of the event acting as editors. All of the contributing authors are researchers working on diverse biological problems that can be approached using nonlinear dynamics. The book will appeal especially to applied math...

  3. Neoclassical transport including collisional nonlinearity.

    Science.gov (United States)

    Candy, J; Belli, E A

    2011-06-10

    In the standard δf theory of neoclassical transport, the zeroth-order (Maxwellian) solution is obtained analytically via the solution of a nonlinear equation. The first-order correction δf is subsequently computed as the solution of a linear, inhomogeneous equation that includes the linearized Fokker-Planck collision operator. This equation admits analytic solutions only in extreme asymptotic limits (banana, plateau, Pfirsch-Schlüter), and so must be solved numerically for realistic plasma parameters. Recently, numerical codes have appeared which attempt to compute the total distribution f more accurately than in the standard ordering by retaining some nonlinear terms related to finite-orbit width, while simultaneously reusing some form of the linearized collision operator. In this work we show that higher-order corrections to the distribution function may be unphysical if collisional nonlinearities are ignored.

  4. Nonlinear photoacoustic spectroscopy of hemoglobin.

    Science.gov (United States)

    Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P; Xia, Jun; Wang, Lihong V

    2015-05-18

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.

  5. Nonlinear photoacoustic spectroscopy of hemoglobin

    International Nuclear Information System (INIS)

    Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.; Xia, Jun; Wang, Lihong V.

    2015-01-01

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography

  6. Nonlinear Deformable-body Dynamics

    CERN Document Server

    Luo, Albert C J

    2010-01-01

    "Nonlinear Deformable-body Dynamics" mainly consists in a mathematical treatise of approximate theories for thin deformable bodies, including cables, beams, rods, webs, membranes, plates, and shells. The intent of the book is to stimulate more research in the area of nonlinear deformable-body dynamics not only because of the unsolved theoretical puzzles it presents but also because of its wide spectrum of applications. For instance, the theories for soft webs and rod-reinforced soft structures can be applied to biomechanics for DNA and living tissues, and the nonlinear theory of deformable bodies, based on the Kirchhoff assumptions, is a special case discussed. This book can serve as a reference work for researchers and a textbook for senior and postgraduate students in physics, mathematics, engineering and biophysics. Dr. Albert C.J. Luo is a Professor of Mechanical Engineering at Southern Illinois University, Edwardsville, IL, USA. Professor Luo is an internationally recognized scientist in the field of non...

  7. NONLINEAR DYNAMICS OF ORGANIZATION DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Денис Антонович БУШУЕВ

    2016-02-01

    Full Text Available The nonlinear behavior of organizations in development projects is considered. The nonlinear behavior is initiated in the growth of organizations and requires a restructuring of governance in identifying dysfunctions. Such a restructuring is needed in the area of soft components, determining the organizational levels of competence in the management of projects, programs, portfolios and heads of the Project Management Office. An important component of the strategic development of the organization is the proposed concept for formation and management of development programs in the context according to their life cycle. It should take into account the non-linear behavior of the soft components of the system and violation of functional processes of the organization. The specific management syndromes of projects and programs are considered. Such as syndromes time management project linked to the singular points of the project. These syndromes are "shift to the right", "point of no return", "braking at the end of the project" and others.

  8. Nonlinear operators and their propagators

    International Nuclear Information System (INIS)

    Schwartz, C.

    1997-01-01

    Mathematical physicists are familiar with a large set of tools designed for dealing with linear operators, which are so common in both the classical and quantum theories; but many of those tools are useless with nonlinear equations of motion. In this work a general algebra and calculus is developed for working with nonlinear operators: The basic new tool being the open-quotes slash product,close quotes defined by A(1+εB) =A+εA/B+O(ε 2 ). For a generic time development equation, the propagator is constructed and then there follows the formal version of time dependent perturbation theory, in remarkable similarity to the linear situation. A nonperturbative approximation scheme capable of producing high accuracy computations, previously developed for linear operators, is shown to be applicable as well in the nonlinear domain. A number of auxiliary mathematical properties and examples are given. copyright 1997 American Institute of Physics

  9. Nonlinear optics an analytical approach

    CERN Document Server

    Mandel, Paul

    2010-01-01

    Based on the author's extensive teaching experience and lecture notes, this textbook provides a substantially analytical rather than descriptive presentation of nonlinear optics. Divided into five parts, with most chapters corresponding to a two-hour lecture, the book begins with a unique account of the historical development from Kirchhoff's law for the black-body radiation to Planck's quantum hypothesis and Einstein's discovery of spontaneous emission - providing all the explicit proofs. The subsequent sections deal with matter quantization, ultrashort pulse propagation in 2-level media, cavity nonlinear optics, chi(2) and chi(3) media. For graduate and PhD students in nonlinear optics or photonics, while also representing a valuable reference for researchers in these fields.

  10. Nonlinear photoacoustic spectroscopy of hemoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.; Xia, Jun; Wang, Lihong V., E-mail: LHWANG@WUSTL.EDU [Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130 (United States)

    2015-05-18

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.

  11. Optimization for nonlinear inverse problem

    International Nuclear Information System (INIS)

    Boyadzhiev, G.; Brandmayr, E.; Pinat, T.; Panza, G.F.

    2007-06-01

    The nonlinear inversion of geophysical data in general does not yield a unique solution, but a single model, representing the investigated field, is preferred for an easy geological interpretation of the observations. The analyzed region is constituted by a number of sub-regions where the multi-valued nonlinear inversion is applied, which leads to a multi-valued solution. Therefore, combining the values of the solution in each sub-region, many acceptable models are obtained for the entire region and this complicates the geological interpretation of geophysical investigations. In this paper are presented new methodologies, capable to select one model, among all acceptable ones, that satisfies different criteria of smoothness in the explored space of solutions. In this work we focus on the non-linear inversion of surface waves dispersion curves, which gives structural models of shear-wave velocity versus depth, but the basic concepts have a general validity. (author)

  12. Nonlinear elasticity in resonance experiments

    Science.gov (United States)

    Li, Xun; Sens-Schönfelder, Christoph; Snieder, Roel

    2018-04-01

    Resonant bar experiments have revealed that dynamic deformation induces nonlinearity in rocks. These experiments produce resonance curves that represent the response amplitude as a function of the driving frequency. We propose a model to reproduce the resonance curves with observed features that include (a) the log-time recovery of the resonant frequency after the deformation ends (slow dynamics), (b) the asymmetry in the direction of the driving frequency, (c) the difference between resonance curves with the driving frequency that is swept upward and downward, and (d) the presence of a "cliff" segment to the left of the resonant peak under the condition of strong nonlinearity. The model is based on a feedback cycle where the effect of softening (nonlinearity) feeds back to the deformation. This model provides a unified interpretation of both the nonlinearity and slow dynamics in resonance experiments. We further show that the asymmetry of the resonance curve is caused by the softening, which is documented by the decrease of the resonant frequency during the deformation; the cliff segment of the resonance curve is linked to a bifurcation that involves a steep change of the response amplitude when the driving frequency is changed. With weak nonlinearity, the difference between the upward- and downward-sweeping curves depends on slow dynamics; a sufficiently slow frequency sweep eliminates this up-down difference. With strong nonlinearity, the up-down difference results from both the slow dynamics and bifurcation; however, the presence of the bifurcation maintains the respective part of the up-down difference, regardless of the sweep rate.

  13. Periodic waves in nonlinear metamaterials

    International Nuclear Information System (INIS)

    Liu, Wen-Jun; Xiao, Jing-Hua; Yan, Jie-Yun; Tian, Bo

    2012-01-01

    Periodic waves are presented in this Letter. With symbolic computation, equations for monochromatic waves are studied, and analytic periodic waves are obtained. Factors affecting properties of periodic waves are analyzed. Nonlinear metamaterials, with the continuous distribution of the dielectric permittivity obtained, are different from the ones with the discrete distribution. -- Highlights: ► Equations for the monochromatic waves in transverse magnetic polarization have been studied. ► Analytic periodic waves for the equations have been obtained. ► Periodic waves are theoretically presented and studied in the nonlinear metamaterials.

  14. Nonlinear Optics of Hexaphenyl Nanofibers

    DEFF Research Database (Denmark)

    Balzer, Frank; Al-Shamery, Katharina; Neuendorf, Rolf

    2003-01-01

    The nonlinear optical response of films of needle-shaped para-hexaphenyl nanoaggregates on mica surfaces is investigated. Two-photon luminescence as well as optical second harmonic generation (SHG) are observed following excitation with femtosecond pulses at 770 nm. Polarization dependent...... measurements reveal that the nonlinear optical transition dipole moment is oriented with an angle of 75° with respect to the needles long axes. The absolute value of the macroscopic second-order susceptibility, averaged over a size distribution of p-6P nanoaggregates, is estimated to be of the order of 6...

  15. Nonlinear waves and weak turbulence

    CERN Document Server

    Zakharov, V E

    1997-01-01

    This book is a collection of papers on dynamical and statistical theory of nonlinear wave propagation in dispersive conservative media. Emphasis is on waves on the surface of an ideal fluid and on Rossby waves in the atmosphere. Although the book deals mainly with weakly nonlinear waves, it is more than simply a description of standard perturbation techniques. The goal is to show that the theory of weakly interacting waves is naturally related to such areas of mathematics as Diophantine equations, differential geometry of waves, Poincaré normal forms, and the inverse scattering method.

  16. Nonlinear Control of Heartbeat Models

    Directory of Open Access Journals (Sweden)

    Witt Thanom

    2011-02-01

    Full Text Available This paper presents a novel application of nonlinear control theory to heartbeat models. Existing heartbeat models are investigated and modified by incorporating the control input as a pacemaker to provide the control channel. A nonlinear feedback linearization technique is applied to force the output of the systems to generate artificial electrocardiogram (ECG signal using discrete data as the reference inputs. The synthetic ECG may serve as a flexible signal source to assess the effectiveness of a diagnostic ECG signal-processing device.

  17. Nonlinear phenomena at cyclotron resonance

    International Nuclear Information System (INIS)

    Subbarao, D.; Uma, R.

    1986-01-01

    Finite amplitude electromagnetic waves in a magnetoplasma which typically occur in situations as in present day wave heating, current drives and other schemes in magnetically confined fusion systems, can show qualitatively different absorption and emission characteristics around resonant frequencies of the plasma because of anharmonicity. Linear wave plasma coupling as well as weak nonlinear effects such as parametric instabilities generally overlook this important effect even though the thresholds for the two phenomena as shown here are comparable. Though the effects described here are relevant to a host of nonlinear resonance effects in fusion plasmas, the authors mainly limit themselves to ECRH

  18. Field guide to nonlinear optics

    CERN Document Server

    Powers, Peter E

    2013-01-01

    Optomechanics is a field of mechanics that addresses the specific design challenges associated with optical systems. This [i]Field Guide [/i]describes how to mount optical components, as well as how to analyze a given design. It is intended for practicing optical and mechanical engineers whose work requires knowledge in both optics and mechanics. This Field Guide is designed for those looking for a condensed and concise source of key concepts, equations, and techniques for nonlinear optics. Topics covered include technologically important effects, recent developments in nonlinear optics

  19. Time series with tailored nonlinearities

    Science.gov (United States)

    Räth, C.; Laut, I.

    2015-10-01

    It is demonstrated how to generate time series with tailored nonlinearities by inducing well-defined constraints on the Fourier phases. Correlations between the phase information of adjacent phases and (static and dynamic) measures of nonlinearities are established and their origin is explained. By applying a set of simple constraints on the phases of an originally linear and uncorrelated Gaussian time series, the observed scaling behavior of the intensity distribution of empirical time series can be reproduced. The power law character of the intensity distributions being typical for, e.g., turbulence and financial data can thus be explained in terms of phase correlations.

  20. Finite elements of nonlinear continua

    CERN Document Server

    Oden, John Tinsley

    1972-01-01

    Geared toward undergraduate and graduate students, this text extends applications of the finite element method from linear problems in elastic structures to a broad class of practical, nonlinear problems in continuum mechanics. It treats both theory and applications from a general and unifying point of view.The text reviews the thermomechanical principles of continuous media and the properties of the finite element method, and then brings them together to produce discrete physical models of nonlinear continua. The mathematical properties of these models are analyzed, along with the numerical s

  1. Stability analysis of nonlinear systems with slope restricted nonlinearities.

    Science.gov (United States)

    Liu, Xian; Du, Jiajia; Gao, Qing

    2014-01-01

    The problem of absolute stability of Lur'e systems with sector and slope restricted nonlinearities is revisited. Novel time-domain and frequency-domain criteria are established by using the Lyapunov method and the well-known Kalman-Yakubovich-Popov (KYP) lemma. The criteria strengthen some existing results. Simulations are given to illustrate the efficiency of the results.

  2. Stability Analysis of Nonlinear Systems with Slope Restricted Nonlinearities

    Directory of Open Access Journals (Sweden)

    Xian Liu

    2014-01-01

    Full Text Available The problem of absolute stability of Lur’e systems with sector and slope restricted nonlinearities is revisited. Novel time-domain and frequency-domain criteria are established by using the Lyapunov method and the well-known Kalman-Yakubovich-Popov (KYP lemma. The criteria strengthen some existing results. Simulations are given to illustrate the efficiency of the results.

  3. Adaptive nodes enrich nonlinear cooperative learning beyond traditional adaptation by links.

    Science.gov (United States)

    Sardi, Shira; Vardi, Roni; Goldental, Amir; Sheinin, Anton; Uzan, Herut; Kanter, Ido

    2018-03-23

    Physical models typically assume time-independent interactions, whereas neural networks and machine learning incorporate interactions that function as adjustable parameters. Here we demonstrate a new type of abundant cooperative nonlinear dynamics where learning is attributed solely to the nodes, instead of the network links which their number is significantly larger. The nodal, neuronal, fast adaptation follows its relative anisotropic (dendritic) input timings, as indicated experimentally, similarly to the slow learning mechanism currently attributed to the links, synapses. It represents a non-local learning rule, where effectively many incoming links to a node concurrently undergo the same adaptation. The network dynamics is now counterintuitively governed by the weak links, which previously were assumed to be insignificant. This cooperative nonlinear dynamic adaptation presents a self-controlled mechanism to prevent divergence or vanishing of the learning parameters, as opposed to learning by links, and also supports self-oscillations of the effective learning parameters. It hints on a hierarchical computational complexity of nodes, following their number of anisotropic inputs and opens new horizons for advanced deep learning algorithms and artificial intelligence based applications, as well as a new mechanism for enhanced and fast learning by neural networks.

  4. Nonlinear Spinor Field in Non-Diagonal Bianchi Type Space-Time

    Directory of Open Access Journals (Sweden)

    Saha Bijan

    2018-01-01

    Full Text Available Within the scope of the non-diagonal Bianchi cosmological models we have studied the role of the spinor field in the evolution of the Universe. In the non-diagonal Bianchi models the spinor field distribution along the main axis is anisotropic and does not vanish in the absence of the spinor field nonlinearity. Hence within these models perfect fluid, dark energy etc. cannot be simulated by the spinor field nonlinearity. The equation for volume scale V in the case of non-diagonal Bianchi models contains a term with first derivative of V explicitly and does not allow exact solution by quadratures. Like the diagonal models the non-diagonal Bianchi space-time becomes locally rotationally symmetric even in the presence of a spinor field. It was found that depending on the sign of the coupling constant the model allows either an open Universe that rapidly grows up or a close Universe that ends in a Big Crunch singularity.

  5. Nonlinear optical properties of silicon waveguides

    International Nuclear Information System (INIS)

    Tsang, H K; Liu, Y

    2008-01-01

    Recent work on two-photon absorption (TPA), stimulated Raman scattering (SRS) and optical Kerr effect in silicon-on-insulator (SOI) waveguides is reviewed and some potential applications of these optical nonlinearities, including silicon-based autocorrelation detectors, optical amplifiers, high speed optical switches, optical wavelength converters and self-phase modulation (SPM), are highlighted. The importance of free carriers generated by TPA in nonlinear devices is discussed, and a generalized definition of the nonlinear effective length to cater for nonlinear losses is proposed. How carrier lifetime engineering, and in particular the use of helium ion implantation, can enhance the nonlinear effective length for nonlinear devices is also discussed

  6. Nonlinearity and nonclassicality in a nanomechanical resonator

    Energy Technology Data Exchange (ETDEWEB)

    Teklu, Berihu [Clermont Universite, Blaise Pascal University, CNRS, PHOTON-N2, Institut Pascal, Aubiere Cedex (France); Universita degli Studi di Milano, Dipartimento di Fisica, Milano (Italy); Ferraro, Alessandro; Paternostro, Mauro [Queen' s University, Centre for Theoretical Atomic, Molecular, and Optical Physics, School of Mathematics and Physics, Belfast (United Kingdom); Paris, Matteo G.A. [Universita degli Studi di Milano, Dipartimento di Fisica, Milano (Italy)

    2015-12-15

    We address quantitatively the relationship between the nonlinearity of a mechanical resonator and the nonclassicality of its ground state. In particular, we analyze the nonclassical properties of the nonlinear Duffing oscillator (being driven or not) as a paradigmatic example of a nonlinear nanomechanical resonator. We first discuss how to quantify the nonlinearity of this system and then show that the nonclassicality of the ground state, as measured by the volume occupied by the negative part of the Wigner function, monotonically increases with the nonlinearity in all the working regimes addressed in our study. Our results show quantitatively that nonlinearity is a resource to create nonclassical states in mechanical systems. (orig.)

  7. Statistical methods in nonlinear dynamics

    Indian Academy of Sciences (India)

    Sensitivity to initial conditions in nonlinear dynamical systems leads to exponential divergence of trajectories that are initially arbitrarily close, and hence to unpredictability. Statistical methods have been found to be helpful in extracting useful information about such systems. In this paper, we review briefly some statistical ...

  8. Cosmological effects of nonlinear electrodynamics

    International Nuclear Information System (INIS)

    Novello, M; Goulart, E; Salim, J M; Bergliaffa, S E Perez

    2007-01-01

    It will be shown that a given realization of nonlinear electrodynamics, used as a source of Einstein's equations, generates a cosmological model with interesting features, namely a phase of current cosmic acceleration, and the absence of an initial singularity, thus pointing to a way of solving two important problems in cosmology

  9. Nonlinearity, Conservation Law and Shocks

    Indian Academy of Sciences (India)

    However, genuine nonlinearity is always present in an ideal gas. The conservation form of the equation (25) brings in shocks which cut off the growing part of the amplitUde as shown in. Figure 15. Acknowledgements. The author sincerely thanks the two referees whose valuable comments led to an improvement of the ...

  10. Impurity solitons with quadratic nonlinearities

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Torres, Juan P-; Torner, Lluis

    1998-01-01

    We fmd families of solitary waves mediated by parametric mixing in quadratic nonlinear media that are localized at point-defect impurities. Solitons localized at attractive impurities are found to be dynamically stable. It is shown that localization at the impurity modifies strongly the soliton...

  11. Nonlinear materials for frequency conversion

    International Nuclear Information System (INIS)

    Velsko, S.P.; Eimerl, D.

    1988-01-01

    Two figures of merit, the threshold power (P/sub th/) and the limiting volume (V/sub min/) can be used to compare the relative efficiency and economy of new harmonic generating crystals. The properties of barium metaborate and L-Arginine phosphate are used to illustrate the effect of nonlinearity, birefringence, and damage threshold on these figures of merit

  12. Dynamics of nonlinear feedback control

    NARCIS (Netherlands)

    Snippe, H.P.; Hateren, J.H. van

    Feedback control in neural systems is ubiquitous. Here we study the mathematics of nonlinear feedback control. We compare models in which the input is multiplied by a dynamic gain (multiplicative control) with models in which the input is divided by a dynamic attenuation (divisive control). The gain

  13. Nonlinear Markov processes: Deterministic case

    International Nuclear Information System (INIS)

    Frank, T.D.

    2008-01-01

    Deterministic Markov processes that exhibit nonlinear transition mechanisms for probability densities are studied. In this context, the following issues are addressed: Markov property, conditional probability densities, propagation of probability densities, multistability in terms of multiple stationary distributions, stability analysis of stationary distributions, and basin of attraction of stationary distribution

  14. Nonlinear Dynamics of Nanomechanical Resonators

    Science.gov (United States)

    Ramakrishnan, Subramanian; Gulak, Yuiry; Sundaram, Bala; Benaroya, Haym

    2007-03-01

    Nanoelectromechanical systems (NEMS) offer great promise for many applications including motion and mass sensing. Recent experimental results suggest the importance of nonlinear effects in NEMS, an issue which has not been addressed fully in theory. We report on a nonlinear extension of a recent analytical model by Armour et al [1] for the dynamics of a single-electron transistor (SET) coupled to a nanomechanical resonator. We consider the nonlinear resonator motion in both (a) the Duffing and (b) nonlinear pendulum regimes. The corresponding master equations are derived and solved numerically and we consider moment approximations as well. In the Duffing case with hardening stiffness, we observe that the resonator is damped by the SET at a significantly higher rate. In the cases of softening stiffness and the pendulum, there exist regimes where the SET adds energy to the resonator. To our knowledge, this is the first instance of a single model displaying both negative and positive resonator damping in different dynamical regimes. The implications of the results for SET sensitivity as well as for, as yet unexplained, experimental results will be discussed. 1. Armour et al. Phys.Rev.B (69) 125313 (2004).

  15. Oscillating solitons in nonlinear optics

    Indian Academy of Sciences (India)

    The study of solitons in those physical systems reveals some exciting .... With the following power series expansions for g(z,t) and f(z,t): g(z,t) = εg1(z,t) + ... If nonlinearity γ (z) is also taken as a function in figure 1b, the periodic and oscillation.

  16. Oscillating solitons in nonlinear optics

    Indian Academy of Sciences (India)

    ... are derived, and the relevant properties and features of oscillating solitons are illustrated. Oscillating solitons are controlled by the reciprocal of the group velocity and Kerr nonlinearity. Results of this paper will be valuable to the study of dispersion-managed optical communication system and mode-locked fibre lasers.

  17. Nonlinear dynamics and plasma transport

    International Nuclear Information System (INIS)

    Antonsen, T.M. Jr.; Drake, J.F.; Finn, J.M.; Guzdar, P.N.; Hassam, A.B.; Sagdeev, R.Z.

    1992-01-01

    In this paper we summarize the progress made over the last year in three different areas of research: (a) shear flow generation and reduced transport in fluids and plasma, (b) nonlinear dynamics and visualization of 3D flows, and (c) application of wavelet analysis to the study of fractal dimensions in experimental and numerical data

  18. Analysis of Nonlinear Dynamic Structures

    African Journals Online (AJOL)

    Bheema

    work a two degrees of freedom nonlinear system with zero memory was ... FRF is the most widely used method in structural dynamics which gives information about the ..... 3.6, which is the waterfall diagram of the same response, as well.

  19. Nonlinear Multigrid for Reservoir Simulation

    DEFF Research Database (Denmark)

    Christensen, Max la Cour; Eskildsen, Klaus Langgren; Engsig-Karup, Allan Peter

    2016-01-01

    efficiency for a black-oil model. Furthermore, the use of the FAS method enables a significant reduction in memory usage compared with conventional techniques, which suggests new possibilities for improved large-scale reservoir simulation and numerical efficiency. Last, nonlinear multilevel preconditioning...

  20. Halo Mitigation Using Nonlinear Lattices

    CERN Document Server

    Sonnad, Kiran G

    2005-01-01

    This work shows that halos in beams with space charge effects can be controlled by combining nonlinear focusing and collimation. The study relies on Particle-in-Cell (PIC) simulations for a one dimensional, continuous focusing model. The PIC simulation results show that nonlinear focusing leads to damping of the beam oscillations thereby reducing the mismatch. It is well established that reduced mismatch leads to reduced halo formation. However, the nonlinear damping is accompanied by emittance growth causing the beam to spread in phase space. As a result, inducing nonlinear damping alone cannot help mitigate the halo. To compensate for this expansion in phase space, the beam is collimated in the simulation and further evolution of the beam shows that the halo is not regenerated. The focusing model used in the PIC is analysed using the Lie Transform perturbation theory showing that by averaging over a lattice period, one can reuduce the focusing force to a form that is identical to that used in the PIC simula...